阅读说明：本技术 图像形成装置和光学传感器 (Image forming apparatus and optical sensor ) 是由 荒木隆一 于 2019-09-05 设计创作，主要内容包括：本申请涉及图像形成装置和光学传感器。一种图像形成装置包括被配置为检测在中间转印带上形成的图像的光学传感器。该光学传感器包括在基板上的第一LED、第二LED、第一PD和第二PD。该第一PD被布置在这样的位置,在该位置可以接收到从第一LED发射的光的镜面反射光,并且可以接收到从第二LED发射的光的散射反射光。该第二PD被布置在这样的位置,在该位置可以接收到从第二LED发射的光的散射反射光。该第一PD的光接收面和该第二PD的光接收面以不同角度被形成。该第一PD的光接收面具有小于该第二PD的光接收面的面积的面积。(The present application relates to an image forming apparatus and an optical sensor. An image forming apparatus includes an optical sensor configured to detect an image formed on an intermediate transfer belt. The optical sensor includes a first LED, a second LED, a first PD and a second PD on a substrate. The first PD is arranged at a position where specular reflection light of light emitted from the first LED can be received and scattered reflection light of light emitted from the second LED can be received. The second PD is disposed at a position where scattered reflected light of light emitted from the second LED can be received. The light receiving surface of the first PD and the light receiving surface of the second PD are formed at different angles. The light receiving face of the first PD has an area smaller than that of the second PD.)

1. An image forming apparatus, comprising:

an image forming unit configured to form an image;

an image bearing member configured to bear an image formed by the image forming unit;

a transfer portion in which the image is transferred from the image bearing member to a sheet;

a sensor configured to detect reflected light from a detection image formed on the image bearing member; and

a control device configured to control the image forming unit to form the detection image on the image bearing member and control the sensor to detect the reflected light from the detection image,

wherein the sensor comprises:

a substrate;

a first light emitting element provided on the substrate;

a second light emitting element provided on the substrate;

a first light receiving element provided on the substrate and configured to receive specular reflection light from the detection image in a case where the first light emitting element irradiates the detection image with light; and

a second light receiving element provided on the substrate and configured to receive scattered reflected light from the detection image in a case where the second light emitting element irradiates the detection image with light, an

Wherein an area of a light receiving face of the first light receiving element is smaller than an area of a light receiving face of the second light receiving element.

2. The image forming apparatus according to claim 1,

wherein a light-receiving surface of the first light-receiving element has a rectangular shape, and is formed such that a side of the rectangle is inclined at a predetermined angle with respect to a direction in which the image is conveyed by the transfer portion, an

Wherein the light receiving surface of the second light receiving element has a rectangular shape, and is formed in a region in which the light receiving surface can be formed such that: the light receiving surface is formed up to a limit of the area in a direction orthogonal to a direction in which the image is conveyed by the transfer portion.

3. The image forming apparatus according to claim 1, wherein the first light receiving element is configured to receive scattered reflected light from the detection image in a case where the second light emitting element irradiates the detection image with light.

4. The image forming apparatus according to claim 1,

wherein the image forming unit includes a plurality of image forming units configured to form images of different colors,

wherein the control device is configured to control a black image forming unit included in the plurality of image forming units to form a black detection image, control the first light emitting element to emit light, control the first light receiving element to receive specular reflection light from the black detection image, and control the density of an image to be formed by the black image forming unit based on a result of receiving the specular reflection light by the first light receiving element, and

wherein the control device is configured to control another image forming unit included in the plurality of image forming units to form a color detection image, control the second light emitting element to emit light, control the second light receiving element to receive scattered reflected light from the color detection image, and control the density of an image to be formed by the another image forming unit based on a result of receiving the scattered reflected light by the second light receiving element.

5. The image forming apparatus according to claim 1,

wherein the image forming unit includes a plurality of image forming units configured to form images of different colors, an

Wherein the control device is configured to control the plurality of image forming units to form a pattern image for detecting color mismatch, control the first light emitting element to emit light, control the first light receiving element to receive specular reflection light from the pattern image, and control the detected color mismatch.

6. The image forming apparatus according to claim 1,

wherein the image forming unit includes a plurality of image forming units configured to form images of different colors, an

Wherein the control device is configured to control the plurality of image forming units to form a pattern image for detecting color mismatch, control the second light reflecting element to emit light, control the first light receiving element to receive scattered reflected light from the pattern image, and control the detected color mismatch.

7. An optical sensor, comprising:

a substrate;

a first light emitting element provided on the substrate;

a first light receiving element provided on the substrate and configured to receive specular reflection light from an object to be measured in a case where the first light emitting element irradiates the object to be measured with light;

a second light emitting element provided on the substrate; and

a second light receiving element provided on the substrate and configured to receive scattered reflected light from the object to be measured in a case where the second light emitting element irradiates the object to be measured with light,

wherein the first light receiving element has a light receiving face having an area larger than that of the second light receiving element.

8. The optical sensor according to claim 7, wherein the first light receiving element is configured to receive scattered reflected light from the object to be measured in a case where the second light emitting element irradiates the object to be measured with light.

9. The optical sensor according to claim 7, wherein,

wherein a light receiving face of the first light receiving element has a rectangular shape,

wherein a light receiving face of the second light receiving element has a rectangular shape, an

Wherein the second light receiving element has an angle of a virtual line connecting diagonal corners of the light receiving face different from an angle of a virtual line connecting diagonal corners of the light receiving face of the first light receiving element.

Technical Field

The present disclosure relates to an optical sensor including a plurality of light emitting elements configured to irradiate an image bearing member with light, and a plurality of light receiving elements configured to receive reflected light of the light emitted from the plurality of light emitting elements, and an image forming apparatus including the optical sensor.

Background

An electrophotographic image forming apparatus is configured to form images of colors of yellow (Y), magenta (M), cyan (C), and black (K) on a sheet by an electrophotographic process of charging, exposure, development, and transfer. The density of an image formed on a sheet varies depending on the temperature and humidity of the image forming apparatus, the number of prints of the image forming apparatus, and the operation time of the image forming apparatus. To solve this problem, the image forming apparatus is configured to form a test image for density detection on an image bearing member different from the sheet, detect the test image for density detection by an optical sensor included in the image forming apparatus, and adjust the image density based on the result of the detection.

The image forming apparatus is also configured to superimpose images of different colors to form a mixed color image. Therefore, when the image forming positions of the yellow image, the magenta image, the cyan image, and the black image are different, the chromaticity of the mixed-color image cannot be the desired chromaticity. This is called "color mismatch". It is known that the color mismatch also varies depending on the temperature and humidity of the image forming apparatus, the number of prints of the image forming apparatus, and the operation time of the image forming apparatus, as with the density of the image described above. To solve this problem, the image forming apparatus is configured to correct color mismatch before the chromaticity of the color image is changed. For example, the image forming apparatus is configured to form a pattern image for detecting color mismatch on an image bearing member, detect the pattern image for detecting color mismatch by an optical sensor, and adjust an image forming position having a corresponding color based on the detection result.

An optical sensor included in the image forming apparatus includes a light emitter and a light receiver configured to receive reflected light from a detection image (a test image and a pattern image) on an image bearing member. Methods of detecting the detection image by the optical sensor include a specular reflection light method of detecting specular reflection light from the detection image, and a scattered reflection light method (diffuse reflection light method) of detecting scattered reflection light from the detection image. For example, the image forming apparatus described in japanese patent application laid-open No. hei 10-031333 is configured to perform a process of detecting specular reflection light from a detection image and a process of detecting scattered reflection light from the detection image by an optical sensor including two light emitting elements and two light receiving elements.

However, the optical sensor described in japanese patent application laid-open No. hei 10-031333 is assembled by soldering a bullet (bullet) light emitting element and a bullet light receiving element on a substrate, and thus it is difficult to reduce the size of the optical sensor. Further, when a light receiving element for detecting color mismatch and a light receiving element for detecting image density are to be mounted on one sensor, possible arrangements of those light receiving elements are limited, and thus it is difficult for the optical sensor to receive reflected light from a detection image at an ideal angle. Therefore, in an image forming apparatus including an optical sensor including a bullet element for detecting color mismatch and a bullet element for detecting image density, there is a fear that the color mismatch amount and the image density cannot be detected with high accuracy.

Furthermore, the inventors of the present disclosure have found that a light receiving pattern suitable for an object to be measured is required. Specifically, the light receiving mode includes a mode in which a change in the sensor output value of the optical sensor is steep and a mode in which a change in the sensor output value of the optical sensor is gentle. For example, a pattern in which the sensor output changes steeply is suitable for detecting a pattern image for detecting color mismatch. This is because in the color mismatch detection, it is desirable to detect the time at which the pattern image reaches the detection area of the sensor with high accuracy. Meanwhile, for example, a mode in which the sensor output changes gently is suitable for detecting a test image for detecting density. This is because when the sensor output changes steeply, the sensor output value changes due to the inconsistency of the density of the test image for detecting the density.

In view of the above-described problems, in order to measure different objects to be measured, a configuration is considered in which the conveying speed of the detection image (test image and pattern image) varies depending on the objects to be measured. However, an image to be formed on a sheet and a detection image are formed on the same image bearing member, and therefore when the conveying speed of the image bearing member is reduced to form the detection image, the downtime is disadvantageously increased. It is an object of the present disclosure to reduce the size of an optical sensor configured to enable measurements to be adapted to different objects to be measured.

Disclosure of Invention

An image forming apparatus according to the present disclosure includes: an image forming unit configured to form an image; an image bearing member configured to bear an image formed by the image forming unit; a transfer portion in which an image is transferred from an image bearing member onto a sheet; a sensor configured to detect reflected light from a detection image formed on the image bearing member; and a control device configured to control the image forming unit to form the detection image on the image bearing member and to control the sensor to detect the reflected light from the detection image, the sensor including: a substrate; a first light emitting element provided on the substrate; a second light emitting element provided on the substrate; a first light receiving element provided on the substrate and configured to receive specular reflection light from the detection image in a case where the first light emitting element irradiates the detection image with light; and a second light receiving element provided on the substrate and configured to receive scattered reflected light from a detection image in a case where the second light emitting element irradiates the detection image with light, and wherein an area of a light receiving surface of the first light receiving element is smaller than an area of a light receiving surface of the second light receiving element.

Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).

Drawings

Fig. 1 is a schematic cross-sectional view of an image forming apparatus according to at least one embodiment of the present disclosure.

Fig. 2 is a schematic diagram of a main part of the optical sensor.

Fig. 3A and 3B are schematic views of the main part of an optical sensor including a bullet element.

Fig. 4 is a control block diagram of the image forming apparatus.

Fig. 5 is an explanatory diagram of a first pattern image for detecting color mismatch.

Fig. 6 is a diagram illustrating an example of an analog signal corresponding to a result of detecting a first pattern image for detecting color mismatch.

Fig. 7A and 7B are explanatory diagrams of a second pattern image for detecting color mismatch.

Fig. 8 is a diagram illustrating an example of an analog signal corresponding to a result of detecting a first pattern image for detecting color mismatch.

Fig. 9 is a diagram showing an example of an analog signal corresponding to a result of detecting the second pattern image for detecting color mismatch.

Fig. 10A and 10B are explanatory diagrams of a test image for detecting image density.

Fig. 11 is a diagram showing an example of an analog signal corresponding to a result of detecting a first test image for detecting image density.

Fig. 12 is a diagram showing an example of an analog signal corresponding to a result of detecting the second test image for detecting the image density.

Fig. 13 is an explanatory view of a light receiving surface of the optical sensor.

Fig. 14A is an explanatory diagram of a detection state of the first PD, and fig. 14B is an explanatory diagram of an analog signal.

Fig. 15 is a flowchart showing a color mismatch detection process.

Fig. 16 is a flowchart showing the image density detection processing.

Detailed Description

At least one embodiment of the present disclosure will now be described in detail with reference to the accompanying drawings.

General arrangement

FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 according to at least one embodiment. The image forming apparatus 100 includes photosensitive drums 1a to 1d, charging devices 2a to 2d, exposure devices 15a to 15d, developing devices 16a to 16d, an intermediate transfer belt 5, a belt supporting roller 3, a transfer roller 4, and a fixing device 17. In the following description, the photosensitive drums 1a to 1d, the charging devices 2a to 2d, the exposure devices 15a to 15d, and the developing devices 16a to 16d are referred to as "image forming units 10", and the "image forming units 10" are configured to form yellow (Y), cyan (C), magenta (M), and black (K) toner images. The letter "a" suffixed to the reference numeral represents a configuration for forming a yellow image. The letter "b" suffixed to reference numerals represents a configuration for forming a cyan image. The letter "c" suffixed to the reference numeral represents a configuration for forming a magenta image. The letter "d" suffixed to the reference numeral represents a configuration for forming a black image.

The intermediate transfer belt 5 is looped around a plurality of rollers including a driving roller and a belt supporting roller 3. The toner image formed by the image forming unit 10 is transferred to the intermediate transfer belt 5. The intermediate transfer belt 5 serves as an image bearing member configured to bear and convey a toner image. Further, the intermediate transfer belt 5 also serves as an intermediate transfer member to which the toner image is transferred. The transfer roller 4 is disposed on the side opposite to the belt supporting roller 3 with respect to the intermediate transfer belt 5. The nip portion N formed by the transfer roller 4 pressing the intermediate transfer belt 5 is referred to as a "transfer portion". The sheet is conveyed to the nip portion N by the conveying roller. The transfer roller 4 is configured to transfer the toner image formed on the intermediate transfer belt 5 onto a sheet at the nip portion N.

The photosensitive drums 1a, 1b, 1c, and 1d each rotate in the direction of arrow a. The photosensitive drums 1a, 1b, 1c, and 1d each have a photosensitive layer on the surface thereof. Photosensitive drums 1a, 1b, 1c, and 1d serve as photosensitive members. The charging devices 2a, 2b, 2c, and 2d are configured to charge the surfaces of the photosensitive drums 1a, 1b, 1c, and 1d, respectively. The exposure devices 15a, 15b, 15c, and 15d are configured to expose the charged surfaces of the photosensitive drums 1a, 1b, 1c, and 1d to light, respectively. The surfaces of the photosensitive drums 1a, 1b, 1c, and 1d are scanned with laser light emitted from the exposure devices 15a, 15b, 15c, and 15d to form electrostatic latent images on the surfaces of the photosensitive drums 1a, 1b, 1c, and 1d, respectively. The developing devices 16a, 16b, 16c, and 16d are configured to develop the electrostatic latent images with toner (developer) to form toner images of the respective colors on the photosensitive drums 1a, 1b, 1c, and 1d, respectively.

The driving roller that rotates the intermediate transfer belt 5 in the direction of arrow B. The toner images of the respective colors formed on the photosensitive drums 1a, 1b, 1c, and 1d are sequentially transferred onto an intermediate transfer belt 5 (i.e., an image bearing member) in an overlapping manner. As a result, a full-color toner image 6 is formed on the intermediate transfer belt 5.

The rotating intermediate transfer belt 5 conveys the toner image 6 to the nip portion N. The toner image 6 is transferred onto the sheet while passing through the nip portion N. The sheet having the toner image 6 transferred thereto is conveyed to a fixing device 17 by a conveying belt 12. The fixing device 17 includes a heater 171. The heater 171 is configured to heat the toner image 6 to fix the toner image 6 onto the sheet. Then, the sheet is conveyed to a tray (not illustrated) of the image forming apparatus 100. In this way, the image forming process by the image forming apparatus 100 ends.

An optical sensor 7 is disposed on the downstream side of the photosensitive drum 1d in the conveying direction (direction B) of the intermediate transfer belt 5. The optical sensor 7 is configured to detect a pattern image for detecting color mismatch and a test image for detecting image density, which are formed on the intermediate transfer belt 5. The result of detecting the pattern image is used to determine the amount of color mismatch, which is used for color mismatch correction. The result of detecting the test image is used to determine a correction amount, which is used for image density correction. Hereinafter, when the pattern image and the test image are not distinguished, the pattern image and the test image are referred to as "detection images".

The toner images of the respective colors transferred from the photosensitive drums 1a to 1d onto the intermediate transfer belt 5 may be shifted in the transfer position on the intermediate transfer belt 5. This is known to be caused by an increase in the temperature of the exposure devices 15a to 15 d. The shift in the transfer position causes color mismatch, which changes the hue and hue of the full-color image. To solve this problem, the image forming apparatus 100 is configured to detect a pattern image by the optical sensor 7, and correct color mismatch from the detection result.

Further, the image forming apparatus 100 may vary in density of an image to be formed due to an increase in use environment (temperature and humidity) and the number of prints. To solve this problem, the image forming apparatus 100 is configured to detect a test image by the optical sensor 7, and perform image density correction in which image forming conditions regarding image density are controlled based on the result of detecting the test image. In this case, the image forming conditions regarding the image density include, for example, the intensity of laser light to be emitted by the exposure devices 15a to 15d, the developing bias to be applied to the developing devices 16a to 16d, the charging bias to be applied to the charging devices 2a to 2d, or the transfer bias to be applied to the transfer roller 4. In order to correct the image density, the image forming apparatus 100 may control a plurality of image forming conditions, or only one specific image forming condition.

Optical sensor

Fig. 2 is an explanatory diagram of the optical sensor 7. The optical sensor 7 includes two light emitting elements and two light receiving elements. The optical sensor includes two Light Emitting Diodes (LEDs) (a first LED701 and a second LED 702) as light emitting elements. The optical sensor 7 includes two Photodiodes (PDs) (first PDs 711 and 712) as light receiving elements. The first LED701, the second LED702, the first PD711, and the second PD 702 are arranged side by side in a predetermined direction on a predetermined surface (mounting surface) of the same substrate 201, and are bonded to the surface by die bonding and wire bonding.

The substrate 201 is, for example, a Printed Circuit Board (PCB), but the present disclosure is not limited thereto. The first LED701, the second LED702, the first PD711, and the second PD 702 are electrically connected to a power supply circuit (not shown) and a detection circuit (not shown) via the substrate 201.

The first LED701 is configured to emit light (the intermediate transfer belt 5 or a detection image on the intermediate transfer belt 5) toward the object to be measured. The first PD711 is arranged at a position where specular reflection light from the measured object can be received when the first LED701 emits light. A point P of fig. 2 indicates a position at which light emitted from the first LED701 to the intermediate transfer belt 5 is reflected. In other words, the first LED701 and the first PD711 are arranged such that light emitted from the first LED701 is specularly reflected at the point P (so that the incident angle and the reflection angle are equal), and the reflected light is received by the first PD 711.

The second LED702 is arranged at a position where specular reflection light of light emitted to the intermediate transfer belt 5 is not received by the first PD711 or the second PD 712. In other words, the second LED702 is arranged such that when light emitted from the second LED702 is specularly reflected by the intermediate transfer belt 5, the reflected light is not received by the first PD711 or the second PD712 either. Even when the light emitted from the second LED702 is specularly reflected by the detection image, the specularly reflected light from the detection image is not received by the first PD711 or the second PD 712. The second LED702 is arranged at a position where scattered reflected light of light emitted to the intermediate transfer belt 5 is received by the first PD711 and the second PD 712. The first LED701 and the second LED702 are arranged to illuminate different positions on the intermediate transfer belt 5.

The first PD711 is arranged at a position where specular reflection light of light emitted from the first LED701 onto the intermediate transfer belt 5 and scattered reflection light of light emitted from the second LED702 onto the intermediate transfer belt 5 are received. The second PD712 is arranged at a position where scattered reflected light of light emitted from the second LED702 onto the intermediate transfer belt 5 is received. The second PD712 is not arranged at a position where the specular reflection light of the light emitted from the first LED701 onto the intermediate transfer belt 5 is received. The first PD711 and the second PD712 are not arranged at positions where specular reflection light of light emitted from the second LED702 to the intermediate transfer belt 5 is received.

The substrate 201 is mounted to a housing 203. The housing 203 has a light guide path for guiding irradiation light so that light emitted from the first LED701 and the second LED702 efficiently irradiates the intermediate transfer belt 5. The housing 203 also has a light guide path for guiding the reflected light so that the first PD711 and the second PD712 effectively receive the reflected light from the intermediate transfer belt 5.

In other words, with the light guide path formed in the housing 203, the light emitted from the first LED701 travels in the direction of the optical axis (the one-dot chain line in fig. 2), and irradiates the intermediate transfer belt 5. With the light guide path formed in the housing 203, specular reflection light from the object to be measured travels in the direction of the optical axis (one-dot chain line in fig. 2), and reaches the first PD 711.

With the light guide path in the housing 203, light emitted from the second LED702 travels in the direction of the optical axis (single-dot chain line in fig. 2), and irradiates the intermediate transfer belt 5.

When the second LED702 emits light, the first PD711 receives scattered reflected light from the intermediate transfer belt 5 through a light guide path formed in the housing 203. In contrast, when the first LED701 emits light, the first PD711 receives specular reflection light from the intermediate transfer belt 5 through a light guide path formed in the housing 203.

When the image forming apparatus 100 detects a color mismatch based on the result of receiving the specular reflected light, the image forming apparatus 100 causes the first LED701 to emit light, and causes the first PD711 to receive the specular reflected light from the pattern image formed on the intermediate transfer belt 5. This is called "specular reflection color mismatch detection". Further, when the image forming apparatus 100 detects the image density based on the result of receiving the specular reflection light, the image forming apparatus 100 causes the first LED701 to emit light, and causes the first PD711 to receive the specular reflection light from the test image formed on the intermediate transfer belt 5. This is called "specular reflection density detection". Further, when the image forming apparatus 100 detects a color mismatch based on the result of receiving the scattered reflected light, the image forming apparatus 100 causes the second LED702 to emit light, and causes the first PD711 to receive the scattered reflected light from the pattern image formed on the intermediate transfer belt 5. This is called "diffuse reflection color mismatch detection".

When the second LED702 emits light, the second PD712 receives scattered reflected light from the intermediate transfer belt 5 through a light guide path formed in the housing 203. When the image forming apparatus 100 detects a color mismatch based on the result of receiving the scattered reflected light, the image forming apparatus 100 causes the second LED702 to emit light and causes the second PD712 to receive the scattered reflected light from the test image formed on the intermediate transfer belt 5. This is called "scattered reflection density detection".

The first LED701, the second LED702, the first PD711, and the second PD712 are mounted on the same substrate 201, and thus these elements can be mounted substantially in parallel with the intermediate transfer belt 5. Therefore, the deviation of the optical axis from the optical axis center point P can be reduced as compared with the case where the element is formed of a bullet element with a lead pin. Further, the first LED701, the second LED702, the first PD711, and the second PD712 are elements bonded to the substrate 201 by die bonding and wire bonding, and thus can be reduced in element interval. Therefore, the overall size of the optical sensor 7 can be reduced. For example, a typical component (chip) manufactured by crystal growth has a size of about 3mm × 2mm × 1mm, whereas a bullet component has a size of about 5mm × 10mm × 5mm even without lead pins. Therefore, the optical sensor 7 in which the element is bonded to the substrate by die bonding and wire bonding can significantly reduce the part volume, and the size of the optical sensor 7 itself can be reduced.

Now, an optical sensor including a bullet element is described as a comparative example. Fig. 3A and 3B are explanatory views of an optical sensor including a bullet element. When the positional relationship between the light emitting elements 161 and 162 and the light receiving elements 163 and 164 is realized by a relationship similar to that in the case where the elements are bonded onto the substrate by die bonding and wire bonding (irradiation angle, reception angle), it is required to bring the light emitting element 161 and the light receiving element 163 close to each other. An example of the above configuration is shown in fig. 3B. When the light emitting element 161 and the light receiving element 163 have a positional relationship with respect to the intermediate transfer belt 5 like that in fig. 2, the light emitting element 161 and the light receiving element 163 are too close to each other. As a result, the function of the housing 166 provided on the substrate 165 as a light shielding wall is suppressed. Therefore, in order to prevent the light emitting elements 161 and 162 and the light receiving elements 163 and 164 from interfering with the light shielding wall, it is required to increase the interval between the elements as in fig. 3A, but in this case, the size of the optical sensor may increase.

As described above, in the optical sensor 7 of at least one embodiment, the light emitting element and the light receiving element are bonded onto the substrate 201 by die bonding and wire bonding. As the first LED701, the second LED702, the first PD711, and the second PD712 are bonded onto the substrate 201 by die bonding and wire bonding, the distance between the elements can be reduced. As a result, the optical sensor 7 can be downsized compared to the optical sensor including the bullet element (fig. 3A and 3B). Further, the optical sensor 7 may reduce the distance between the first LED701 and the first PD711, thus also increasing the flexibility of design. Therefore, according to the optical sensor 7, the first LED701, the second LED702, the first PD711, and the second PD712 can be arranged in a positional relationship suitable for detecting the specular reflected light and the scattered reflected light from the object to be measured. In particular, in the optical sensor 7 in which the light emitting element is shared or the light receiving element is shared, the specular reflected light and the scattered reflected light from the detection image can be detected more accurately than in the related-art optical sensor including the bullet element.

Controller

Now, a description is returned to the image forming apparatus 100 of at least one embodiment. Fig. 4 is an explanatory diagram of an example of the configuration of a controller configured to control the image forming apparatus 100. The controller 400 includes a Central Processing Unit (CPU)109, a Read Only Memory (ROM)111, and an image formation controller 101. The CPU109 includes an a/D converter 110. The image forming controller 101 includes an exposure device controller 112, a developing device controller 113, a photosensitive drum controller 114, and an intermediate transfer belt driver 115. The exposure apparatus controller 112 is configured to control the intensity of laser light emitted from light sources included in the exposure apparatuses 15a to 15 d. The developing device controller 113 is configured to control a motor for rotating the developing rollers included in the developing devices 16a to 16 d. The photosensitive drum controller 114 is configured to control motors for rotating the photosensitive drums 1a to 1 d. The intermediate transfer belt driver 115 is configured to control a motor for rotating the intermediate transfer belt 5. The CPU109 is configured to control the image forming apparatus 100 by executing a computer program stored in the ROM 111. In the ROM 111, pattern image data and test image data are stored in addition to the computer program. The pattern image data is to be used to form a pattern image for color mismatch detection, which will be described later, and the test image is to be used to form a test image for image density detection. The controller 40 may be realized not only by executing a computer program but also by a discrete component or a single-chip semiconductor product. The single-chip semiconductor product includes, for example, a Micro Processing Unit (MPU), an Application Specific Integrated Circuit (ASIC), or a system on a chip (SOC).

The CPU109 is configured to control the optical sensor 7 so that the first LED701 and the second LED702 emit light (are lit) independently.

The optical sensor 7 is configured to receive reflected light from the intermediate transfer belt 5 or a detection image formed on the intermediate transfer belt 5 through the first PD711 and the second PD 712. The first PD711 and the second PD712 are configured to output an analog signal obtained by converting the received reflected light into a voltage as a detection result. The CPU109 is configured to acquire analog signals output from the first PD711 and the second PD712 through the a/D converter 110. The CPU109 is configured to store the digital signal into which the analog signal is converted by the a/D converter 110 in a memory (not shown).

The CPU109 is configured to control the exposure devices 15a to 15d, the developing devices 16a to 16d, and the photosensitive drums 1a to 1d through the image formation controller 101 to form detection images on the intermediate transfer belt 5. The CPU109 is configured to control the first LED701 and the second LED702 of the optical sensor 7 to be lit. The first LED701 and the second LED702 are configured to illuminate the surface (front surface) of the intermediate transfer belt 5 on which the detection image is formed and the detection image formed on the intermediate transfer belt 5. The first PD711 and the second PD712 are configured to receive reflected light from the front surface of the intermediate transfer belt 5 and a detection image formed on the intermediate transfer belt 5 to output an analog signal corresponding to the reflected light. The CPU109 is configured to detect a color mismatch amount and an image density from analog signals output from the first PD711 and the second PD712 to perform color mismatch correction and image density correction.

Pattern image

Fig. 5 is an explanatory diagram of a first pattern image for color mismatch detection. The first pattern image includes a color pattern of yellow (yellow is a reference color) and color patterns of other colors (magenta, cyan, and black). The color pattern is an image formed to be inclined at a predetermined angle (for example, 45 °) with respect to the conveying direction of the intermediate transfer belt 5. Two pattern images of the same color are formed. The pattern images of the same color are formed to be inclined in different directions with respect to the conveying direction of the intermediate transfer belt 5.

The first pattern image is used for a case where the first PD711 receives specular reflection light of light emitted from the first LED 701. For example, when the amount of reflected light from the intermediate transfer belt 5 is a predetermined amount or more, the color misregistration amount is detected using the first pattern image. When the front surface glossiness of the intermediate transfer belt 5 is not reduced, the amount of specular reflection light from the front surface of the intermediate transfer belt 5 becomes larger than the amount of specular reflection light from the first pattern image. Therefore, the analog signal value corresponding to the result of receiving the reflected light from the area (the front surface of the intermediate transfer belt 5) in which the first pattern image is not formed becomes higher than the analog signal value corresponding to the result of receiving the reflected light from the first pattern image.

Fig. 6 is a diagram showing an example of an analog signal in a case where reflected light from the first pattern image is detected by the first LED701 and the first PD 711. The analog signal value obtained by the first PD711 upon receiving the reflected light from the color pattern is lower than the analog signal value obtained by the first PD711 upon receiving the reflected light from the front surface of the intermediate transfer belt 5.

The CPU109 is configured to convert the analog signal into a binary signal indicating a first level or a second level based on a first threshold. The converted signal corresponds to the result of the comparison between the analog signal value (fig. 6) and the first threshold value. At this time, the CPU109 determines the first threshold value based on the analog signal value obtained when the specular reflection light from the front surface of the intermediate transfer belt 5 of the light emitted from the first LED701 is received by the first PD 711. Then, the CPU109 detects the color misregistration amount of the color pattern of the first pattern image based on the binary signal described above. Color mismatch correction is a known technique, and a detailed description thereof is omitted here.

Fig. 7A and 7B are explanatory diagrams of a second pattern image for color mismatch detection. The second pattern image includes a color pattern of yellow (yellow is a reference color) and color patterns of other colors (magenta, cyan, and black). However, it should be noted that the color pattern of black of the second pattern image is formed to be superimposed on the color pattern of magenta. The second pattern image is used when scattered reflected light of light emitted from the second LED702 is received by the first PD 711. In other words, when the amount of reflected light from the intermediate transfer belt 5 is not a predetermined amount and above, the color misregistration amount is detected using the second pattern image. In other words, when the amount of reflected light from the intermediate transfer belt 5 is less than a predetermined amount, the color misregistration amount is detected using the second pattern image.

When the glossiness of the intermediate transfer belt 5 is reduced by the abrasion of the intermediate transfer belt 5, the amount of specular reflection light from the front surface of the intermediate transfer belt 5 is reduced. Fig. 8 is a diagram showing an example of an analog signal obtained when reflected light from the first pattern image formed on the intermediate transfer belt 5, which has a reduced amount of specular reflection light, is detected by the first LED701 and the first PD 711. When the amount of specular reflection light from the intermediate transfer belt 4 is reduced, as shown in fig. 6, the difference between the analog signal value obtained when the specular reflection light from the color pattern of the corresponding color is received and the analog signal value obtained when the specular reflection light from the intermediate transfer belt 5 is received is reduced. Therefore, there is a fear that the CPU109 cannot detect the color misregistration amount from the binary signal with high accuracy.

To solve this problem, the second pattern image is formed in a state where the amount of specular reflection light from the intermediate transfer belt 5 is reduced, and scattered reflection light from the second pattern image is detected by the optical sensor 7. The optical sensor 7 receives scattered reflected light of light emitted from the second LED702 through the first PD 711. Fig. 9 is a diagram for illustrating an example of an analog signal obtained when reflected light from the second pattern image formed on the intermediate transfer belt 5, which has a reduced amount of specular reflection light, is detected by the second LED702 and the first PD 711.

As shown in fig. 7A, the second pattern image is different from the first pattern image. Specifically, a color image of black is superimposed on a color image of magenta. When a black color pattern is detected using scattered reflected light, light emitted from the second LED702 is absorbed by the black toner. Therefore, the difference between the amount of scattered reflected light from the color image of only black and the amount of scattered reflected light from the intermediate transfer belt 5 becomes extremely small. In each of the color patterns of black of the second pattern image, the pattern formed using the magenta toner is exposed from the gap of the pattern formed at intervals using the black toner. This is called a "composite pattern". A cross-sectional view of the composite pattern is shown in fig. 7B. The result of detecting the second pattern image including the composite pattern is shown in fig. 9. The analog signal value corresponding to the scattered reflected light from the composite pattern is a value corresponding to the scattered reflected light from the region of the composite pattern formed using the magenta toner. The interval between the patterns of the black toner is determined in advance, and therefore the CPU109 can determine the color misregistration amount of the color pattern of black based on the relative position between the area of the composite pattern formed using the magenta toner and the reference color pattern using the yellow toner.

CPU109 is configured to convert the analog signal (fig. 9) to a binary signal indicative of the first level or the second level based on the second threshold. The converted signal corresponds to the result of the comparison between the analog signal value (fig. 9) and the second threshold value. At this time, the CPU109 determines the second threshold value based on the analog signal value obtained when the scattered reflected light from the front surface of the intermediate transfer belt 5 of the light emitted from the second LED702 is received by the first PD 711. Then, the CPU109 detects the color misregistration amount of the color pattern of the second pattern image based on the binary signal described above. Color mismatch correction is a known technique, and a detailed description thereof is omitted here.

In the image forming apparatus 100 according to at least one embodiment, the color misregistration amount of the image is detected using the pattern images (the first pattern image and the second pattern image) described above. The CPU109 detects the positions of the color patterns of the respective colors to calculate the relative positions of the pattern images of the other colors with respect to the pattern image of the reference color (yellow). The CPU109 determines the color misregistration amount of the corresponding color based on the difference between the calculated relative position and the target relative position. The CPU109 controls the time of writing by the exposure apparatuses 15a to 15d based on the determined color mismatch amount to perform color mismatch correction. Further, the CPU109 may correct the image data based on the detected color mismatch to, for example, suppress the amount of color mismatch that will form an image by the image forming unit 10. The reference color is not limited to yellow, but may be magenta or cyan. Further, a configuration may be adopted in which the CPU109 selects specular reflection color mismatch detection or scattering reflection color mismatch detection in response to a user selecting a color mismatch detection mode via an operation panel (not shown).

Test image

Fig. 10A and 10B are explanatory diagrams of a test image for image density detection. In fig. 10A, an example of a first test image to be detected using specular reflection light for image density detection is shown. In fig. 10B, an example of a second test image to be detected using scattered reflected light for image density detection is shown.

The first test image is used when specular reflection light of light emitted from the first LED701 is received by the first PD 711. In particular, the first test image is used when detecting an image density of black. The black toner absorbs light, and thus the amount of scattered reflected light from a test image of black is extremely small. Therefore, when the density of an image formed of black toner is to be detected, the CPU109 detects scattered reflected light from a test image of black. The first test pattern is formed of gray patterns of four densities of 70%, 50%, 30%, and 10%. The image forming unit 10 forms a first test image based on the image signal value of the test image data. The image signal value of the test image data is predetermined in advance.

The first test image formed on the intermediate transfer belt 5 is read out by the optical sensor 7. The analog signal output from the first PD711 is converted into a digital signal by the a/D converter 110. The CPU109 controls the image forming conditions for the image density based on the difference between the digital signal value and the target value. For example, the CPU109 controls the intensity of laser light emitted from the exposure apparatus 15d through the image formation controller 101 to adjust the image density of black.

Fig. 11 is a diagram showing an example of analog signals obtained when reflected light from the first test image is detected by the first LED701 and the first PD 711. An image of 70% density, which is the highest density of the first test image, has its amount of specular reflection reduced due to the large toner adhesion, coupled with the fact that light is absorbed by the black toner. Therefore, the analog signal value output by the optical sensor 7 (the first PD711) is reduced. In the image of 10% density, which is the lowest density of the first test image, the amount of light absorbed by the black toner decreases, and the toner adhesiveness decreases, as compared with the case of 70% density, with the result that the amount of specular reflection light increases. Therefore, the analog signal value output by the optical sensor 7 (the first PD711) increases.

The second test image is used when scattered reflected light of light emitted from the second LED702 is received by the second PD 712. In particular, the second test image is used when detecting pattern densities of colors such as yellow, magenta, and cyan. The scattered reflectance light is used to detect the image densities of yellow, magenta, and cyan. The second test pattern is formed of gray patterns of four densities of 70%, 50%, 30%, and 10%. A yellow test image is shown in fig. 10B. A second test image of each color of yellow, magenta, and cyan is formed on the intermediate transfer belt 5.

The second test image formed on the intermediate transfer belt 5 is read out by the optical sensor 7. The analog signal output from the second PD712 is converted into a digital signal by the a/D converter 110. The CPU109 controls the image forming conditions for the image density based on the difference between the digital signal value and the target value. In this way, the CPU109 adjusts the image densities of yellow, magenta, and cyan.

Fig. 12 is a diagram showing an example of analog signals obtained when reflected light from the second test image is detected by the second LED702 and the second PD 712. Here, the analog signal for the second test image of yellow is shown. An image of 70% density, which is the highest density of the second test image, is increased in the amount of scattered reflection light because the toner adhesion is large, and in addition, light is reflected by the yellow toner. Therefore, the analog signal value output by the optical sensor 7 (second PD 712) is increased. In the image of 10% density, which is the lowest density of the second test image, the amount of light reflected by the yellow toner decreases and the amount of scattered reflected light decreases, compared to the case of 70% density. Therefore, the analog signal value output by the optical sensor 7 (second PD 712) decreases. The analog signals obtained from the second test images for magenta and cyan exhibited similar trends.

Detection area of optical sensor

Fig. 13 is an explanatory view of the light receiving surface of the optical sensor 7. Fig. 13 is a view of the optical sensor 7 viewed from the side of the intermediate transfer belt 5, in which the shapes of the light receiving surface of the first PD711 and the light receiving surface of the second PD712 on the substrate 201 are shown. The light receiving surface of the first PD711 and the light receiving surface of the second PD712 each have a rectangular shape, but have different sizes and are formed at different angles. In this example, the light receiving face of the second PD712 is formed larger than the light receiving face of the first PD 711. Further, the light receiving face of the first PD711 and the light receiving face of the second PD712 are formed at angles different from each other by 5 ° or more. The light receiving surface has the same shape as the detection area. When the longitudinal direction of the substrate 201 is assumed to be a reference line, the forming angle is defined as the smaller one of the angles between the reference line and the diagonal of the light receiving surface.

The light receiving surface of the first PD711 is formed such that both sides are inclined at a predetermined angle with respect to the conveying direction of the intermediate transfer belt 5. The inclination angle of the light receiving surface of the first PD711 with respect to the conveying direction of the intermediate transfer belt 5 is the same as the inclination angle (for example, 45 °) of each color pattern of the pattern image for detecting color misregistration with respect to the conveying direction of the intermediate transfer belt 5. The length of one side of the light receiving surface of the first PD711 is equal to the length of the width of the color pattern. The width of the diagonal line of the light receiving surface of the first PD711 is equal to the maximum width of the area of the optical sensor 7 where the light receiving surface can be formed. Thus, as the light receiving surface of the first PD711 is thus formed to be inclined, the rising and falling edges of the analog signal output by the first PD711 when receiving the reflected light from the pattern image can be steep. Therefore, the color misregistration amount can be detected with high accuracy.

Fig. 14A and 14B are explanatory diagrams and explanatory diagrams of the detection state of the first PD711 and an analog signal as a detection result. The case of detecting a pattern image for detecting color mismatch is described in fig. 14A and 14B. As shown in fig. 14A, the detection region having the same shape as the light receiving surface of the first PD711 is provided at the same inclination as the inclination of the pattern image with respect to the conveying direction of the intermediate conveyance belt 5. The pattern image is conveyed in the direction of the arrow by the intermediate transfer belt 5 to pass through the detection area of the first PD 711. As a result, as shown in fig. 14B, the analog signal output by the first PD711 has the steepest rising edge and falling edge. In fig. 14B, an analog signal obtained when the second pattern image is measured is shown.

In the case where the positions of the respective color patterns of the pattern image are detected based on a binary signal obtained by converting an analog signal based on a threshold value, when rising and falling edges of the analog signal are steeper, the result is less affected by signal noise. When signal noise occurs in an analog signal, for example, edges of a binary signal vary due to the noise, causing fluctuations in the position of a detected pattern image. The amount of fluctuation becomes smaller as the rising and falling edges of the analog signal become steeper. Therefore, detection errors can be reduced. For this reason, it is desirable that the area of the light receiving face of the first PD711 for detecting color mismatch is reduced.

Further, the light receiving face of the second PD712 receives scattered reflected light of the second LED 702. The result detected by the second PD712 is used to detect the image density. In order to accurately detect the image density, it is desirable that the second PD712 be able to uniformly detect a wider detection area. In order to detect a test image of low density (which reflects a low amount of light), it is preferable that the second PD712 receive as much light as possible to ensure S/N. For this purpose, the light-receiving surface of the second PD712 is formed in a direction orthogonal to the conveying direction of the intermediate transfer belt 5 up to the limit or boundary of the area where the light-receiving surface of the optical sensor 7 can be formed. With this configuration, the second PD712 ensures the maximum S/N without increasing the size of the optical sensor 7.

As described above, the optical sensor 7 has the first PD711 and the second PD712 formed on the substrate 201, and the light receiving surface of the first PD711 is smaller than the light receiving surface of the second PD 712. As a result, the light receiving element for detecting color mismatch and detecting pattern density is formed in a shape, a forming angle, and a size suitable for its use. Therefore, the amount of color misregistration and the image density can be detected with high accuracy without increasing the size of the optical sensor 7.

Color mismatch correction

FIG. 15 is a flow diagram that illustrates processing to detect color misregistration in at least one embodiment.

The CPU109 first detects the amount of light reflected on the front surface of the intermediate transfer belt 5 by the optical sensor 7 (step S1201). The CPU109 controls the first LED701 to emit light. At this time, no image is formed on the intermediate transfer belt 5, so that light from the first LED701 irradiates the front surface of the intermediate transfer belt 5. The first PD711 receives the specular reflection light from the front surface of the intermediate transfer belt 5 to output an analog signal corresponding to the amount of the specular reflection light. The CPU109 acquires an analog signal from the first PD711 to detect the amount of light reflected by the front surface of the intermediate transfer belt 5.

The CPU109 determines whether the acquired amount of light reflected by the front surface of the intermediate transfer belt 5 is a predetermined amount or more (step S1202). Through this processing, the CPU109 determines whether the glossiness of the front surface of the intermediate transfer belt 5 is high.

When the amount of light reflected by the front surface of the intermediate transfer belt 5 is a predetermined amount or more (step S1202: Y), the CPU109 determines that the glossiness of the front surface of the intermediate transfer belt 5 is not decreased. In this case, the CPU109 detects the color misregistration amount using the first pattern image. In other words, the CPU109 transfers the pattern image data P1 to the image formation controller 101, and controls the image formation controller 101 to form the first pattern image on the intermediate transfer belt 5 (step S1203). The CPU109 controls the first LED701 to emit light, and reads out a first pattern image formed on the intermediate transfer belt 5 by the first PD711 (step S1204). In step S1204, the CPU109 acquires an analog signal output from the first PD 711. The CPU109 calculates the color misregistration amount from the results of detecting the first pattern images of the respective colors of yellow, magenta, cyan, and black (step S1207). The CPU109 stores the calculated color mismatch amount in the memory.

When the amount of light reflected by the front surface of the intermediate transfer belt 5 is less than a predetermined amount (step S1202: N), the CPU109 determines that the glossiness of the front surface of the intermediate transfer belt 5 decreases. In this case, the CPU109 detects the color misregistration amount using the second pattern image. In other words, the CPU109 transfers the pattern image data P2 to the image formation controller 101, and controls the image formation controller 101 to form the second pattern image on the intermediate transfer belt 5 (step S1205). The CPU109 controls the second LED702 to emit light, and reads out the second pattern image formed on the intermediate transfer belt 5 by the first PD711 (step S1206). In step S1206, the CPU109 acquires the analog signal output from the first PD 711. Then, the CPU109 controls the process to proceed to step S1207. The CPU109 calculates the amount of color misregistration based on the result of detecting the second pattern images of the respective colors of yellow, magenta, cyan, and black (step S1207). After the process of step S1207 is completed, the CPU109 ends the process of detecting the color misregistration amount.

When the image forming apparatus 100 is to form an image on a sheet, the CPU109 reads out the amount of color mismatch from the memory, and corrects the image forming position of the image to be formed based on the image data according to the amount of color mismatch.

As described above, the CPU109 acquires the amount of color misregistration with the optimal combination of the light emitter and the light receiver using the pattern images for color misregistration detection (the first pattern image and the second pattern image) corresponding to the result of detecting the glossiness of the intermediate transfer belt 5. In the process of detecting the amount of color misregistration, the same element (first PD711) is used on the light receiving side. The position of the light receiving element (first PD711) is fixed, so that the detection accuracy of the amount of color misregistration is increased as compared with the case where the first pattern image and the second pattern image are detected by different light receiving elements. Therefore, the CPU109 can detect an accurate color mismatch amount to perform accurate color mismatch correction.

Image density correction

FIG. 16 is a flow diagram that illustrates image density detection processing in at least one embodiment. In at least one embodiment, the case where image density detection for color is performed after image density detection for black is given, but the order may be reversed.

The CPU109 transfers the test image data TK to the image formation controller 101, and controls the image formation controller 101 to form a test image (first test image) of black on the intermediate transfer belt 5 (step S1301). The CPU109 controls the first LED701 to emit light, and acquires an analog signal from the first PD711 that has received the specular reflection light to read out a test image of black (step S1302). The CPU109 converts the level of an analog signal corresponding to the read black test image into a digital signal value through the a/D converter 110. The CPU109 determines image forming conditions for the image density based on the digital signal value (step S1303). In step S1303, the CPU109 determines a correction amount of the laser intensity of the exposure apparatus 15d as an image forming condition regarding the image density for black, and stores the correction amount in a memory (not shown). When a black image is to be formed, the CPU109 reads out the correction amount from the memory, and controls the density of the black image to be formed by the image forming unit 10 in accordance with the correction amount.

After calculating the correction amount of the image density for black, the CPU109 determines whether the image density detection processing for all the colors of yellow, magenta, and cyan has been performed (step S1304).

When the image density detection processing for all colors has not been performed (step S1304: N), the CPU109 first performs image density detection for yellow. In other words, the CPU109 transfers the test image data TY to the image formation controller 101, and controls the image formation controller 101 to form a test image of yellow (second test image) on the intermediate transfer belt 5 (step S1305). The CPU109 controls the second LED702 to emit light, and acquires an analog signal from the second PD712 that has received the scattered reflected light to read out a test image in yellow (step S1306). The CPU109 converts the level of the analog signal corresponding to the read yellow test image into a digital signal value through an a/D converter. The CPU109 determines the image forming conditions for the image density based on the digital signal value (step S1307). In step S1307, the CPU109 determines the correction amount of the laser intensity of the exposure apparatus 15a as the image forming condition regarding the image density for yellow, and stores the correction amount in a memory (not shown). When a yellow image is to be formed, the CPU109 reads out the correction amount from the memory, and controls the density of the yellow image to be formed by the image forming unit 10 in accordance with the correction amount.

The CPU109 repeats the processing of steps S1305 to S1307 until the image density detection processing for all colors ends. When the image density detection processes for all the colors of yellow, magenta, and cyan have been performed (step S1304: Y), the CPU109 ends the image density detection process.

As described above, the CPU109 acquires the image density with the optimum combination of the light emitter and the light receiver using the test images for image density detection (first test image, second test image) corresponding to the color to be detected. Therefore, the CPU109 can detect the correction amount of the accurate image density to perform the accurate image density correction.

As described above, the image forming apparatus 100 according to at least one embodiment includes the optical sensor 7, and the optical sensor 7 has elements bonded to the same substrate 201 by die bonding and wire bonding. Further, in order to detect the amount of color misregistration and detect the image density, the optical sensor 7 includes light receiving elements different in the light receiving face size and the formation angle. Therefore, the size and cost of the optical sensor 7 itself can be reduced. The image forming apparatus 100 uses the optical sensor 7 in both the specular reflection light method and the scattered reflection light method. Further, the image forming apparatus 100 prepares a detection image for use in the specular reflection light method and a detection image for use in the scattered reflection light method, respectively.

In the process of detecting the amount of color misregistration, the image forming apparatus 100 can realize detection of a pattern image suitable for the state of the intermediate transfer belt 5 by combining the first LED701, the second LED702, and the first PD 722 in an optimum manner. As the shape of the detection area of the first PD711 is formed to be inclined with respect to the conveying direction of the intermediate transfer belt 5 in accordance with the shape of the pattern image, the amount of color misregistration can be detected with high accuracy. Further, in the image density detection process, the image forming apparatus 100 can realize detection of a test image suitable for the color of the test image by an optimal combination of the first LED701, the second LED702, the first PD711, and the second PD 712. The second PD712 is configured to receive scattered reflected light of light from the second LED702 to detect the image density, the second PD712 being formed to have a detection area larger than that of the first PD 711. As a result, the image density for the color test image can be detected with high accuracy.

In order to maximize the detection capability of the optical sensor 7, it is required to compensate the positional relationship among the elements with high accuracy. In the optical sensor 7, the first LED701, the second LED702, the first PD711, and the second PD712 are bonded onto the substrate 201 by die bonding and wire bonding, thereby accurately positioning the first LED701 and the first PD711 used in the specular reflection light method. Meanwhile, positioning among other elements can be performed with a margin. Therefore, the assembling operation of the optical sensor 7 becomes easier than in the related art. As described above, the optical sensor 7 according to the present disclosure can be downsized while enabling measurement to be adapted to different objects to be measured.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

The present application claims the benefit of japanese patent application No.2018-168418, filed on 9/10 of 2018, which is incorporated herein by reference in its entirety.