阅读说明：本技术 激光输出控制装置和激光扫描型显示设备 (Laser output control device and laser scanning type display apparatus ) 是由 秦诚 于 2019-02-15 设计创作，主要内容包括：本发明的目的是抑制杂散光的显示质量的降低。一种激光输出控制装置(101),其通过反馈光源(11)所射出的激光的光强度,调整用于显示图像(M)的光源(11)的控制值,其中,照度判断部(21)获得可推算周围环境的照度的照度信号或从外部控制图像(M)的亮度的要求亮度信号,判断周围环境的亮度,检查时期调整部(22)在照度判断部(21)判定为周围环境暗的场合,与周围环境亮的场合相比较,缩短光源(11)所射出检查用光(Cd)的期间(Q),光源控制部(23)获得光源(11)所射出的检查用光(Cd)的光强度的累积计算值(Sd),调整驱动光源(11)的控制值。(The invention aims to suppress the display quality of stray light from being reduced. A laser output control device (101) adjusts a control value of a light source (11) for displaying an image (M) by feeding back a light intensity of a laser beam emitted from the light source (11), wherein an illuminance judgment unit (21) obtains an illuminance signal capable of estimating the illuminance of the surrounding environment or a required brightness signal for controlling the brightness of the image (M) from the outside to judge the brightness of the surrounding environment, an inspection timing adjustment unit (22) shortens a period (Q) during which inspection light (Cd) is emitted from the light source (11) when the illuminance judgment unit (21) judges that the surrounding environment is dark as compared with when the surrounding environment is bright, and a light source control unit (23) obtains an accumulated calculated value (Sd) of the light intensity of the inspection light (Cd) emitted from the light source (11) to adjust the control value for driving the light source (11).)

1. A laser output control device (101) for adjusting a control value of a light source (11) for displaying an image (M) by feeding back a light intensity of laser light emitted from the light source (11), the laser output control device (101) comprising:

an illuminance determination unit (21) for obtaining an illuminance signal capable of estimating the illuminance of the surrounding environment or a required luminance signal for controlling the luminance of the image (M) from the outside and determining the luminance of the surrounding environment;

an inspection timing adjusting unit (22), wherein when the illuminance judging unit (21) judges that the ambient environment is dark, the inspection timing adjusting unit (22) shortens a period (Q) during which the light source (11) emits inspection light (Cd) compared with when the ambient environment is bright;

and a light source control unit (23) that obtains a cumulative calculated value (Sd) of the light intensity of the inspection light (Cd) emitted by the light source (11), and adjusts the control value for driving the light source (11).

2. The laser output control device according to claim 1, wherein the inspection timing adjustment unit (22) advances a timing (te) at which the emission of the inspection light (Cd) ends in a case where the ambient environment is dark, as compared with a case where the ambient environment is bright.

3. The laser output control device according to claim 1 or 2, wherein the light source control unit (23) makes an intensity of the inspection light (Cd) emitted from the light source (11) when the ambient environment is determined to be dark lower than an intensity of the inspection light (Cd) emitted from the light source (11) when the ambient environment is determined to be bright.

4. The laser output control device according to any one of claims 1 to 3, further comprising a gain control unit (24), wherein the gain control unit (24) switches a gain of a variable amplifier (16) that amplifies an accumulated value of the light intensity;

the gain control unit (24) sets: and the gain is inversely proportional to the period (Q) during which the inspection light (Cd) is emitted.

5. A laser scanning type display device, comprising:

the laser output control device (20) according to any one of claims 1 to 4;

a light source (11) for adjusting the control value by the laser output control device (20);

and a scanning unit (102) that scans the laser light emitted from the light source (11) a plurality of times in a main scanning direction (X), and that scans the laser light in a sub-scanning direction (Y) that is substantially orthogonal to the main scanning direction (X), thereby forming the image (M).

6. The laser scanning type display apparatus according to claim 5, wherein said inspection timing adjustment section (22) starts emission of said inspection light (Cd) before a scanning position of said scanning section (102) reaches a reciprocating switching position (Y4) in said sub scanning direction (Y), and ends emission of said inspection light (Cd) after reaching said reciprocating switching position.

Technical Field

The present invention relates to a laser output control device that controls a laser light source and a laser scanning type display apparatus that scans light emitted from the laser output control device in a two-dimensional manner to form an image.

Background

The laser scanning type display device scans light emitted from a laser output control device on a screen by, for example, a scanning section to form an image. Such a laser scanning type display device has a problem that the intensity of light emitted changes due to a change in temperature of a use environment or the like, and a formed image cannot be displayed with desired luminance or color.

In order to solve such a problem, a technique is known in which the light intensity of the laser beam is detected, and the emission of the laser beam is adjusted based on the detected light intensity, thereby outputting a desired light intensity.

Patent document 1 discloses a technique including a reflection/transmission unit that receives light from a light source, reflects a part of the light as reflected light in the direction of an optical sensor, transmits a part of the light as transmitted light to the scanning unit, and allows the reflected light of the light output from the light source to enter the optical sensor, and performs compensation processing for driving the light source under the condition of a detection signal of the optical sensor. The light detected by the photosensor is reflected light (reflected light of the light for detection) of the light (light for detection) emitted from the light source driven at a predetermined output intensity (control value). Incidentally, the detection light is in an invisible area on the screen which cannot be recognized by the user, and is output when the scanning section is directed to the laser light.

A scanning unit of a laser scanning display device performs a plurality of main scans in the left-right direction by light emitted from a light source, and also performs sub-scans in the up-down direction orthogonal to the main scanning direction. The area scannable by the scanning unit is composed of a visible area recognizable by a user and an invisible area invisible by the user in an area other than the visible area. Typically, the visible region is a rectangular region located substantially at the middle of the region that can be scanned by the scanning unit, and the invisible region is a hollow rectangular region surrounding the visible region, and the visible region includes both outer ends in the left-right direction (main scanning direction) and both outer ends in the up-down direction (sub-scanning direction) of the visible region.

As described above, since the inspection light is output when the scanning unit is directed to the laser light in the region on the screen which is not visible to the user, the inspection light on the screen should not be visible to the user.

Patent document 2 discloses a technique in which inspection light is emitted from a light source in the vicinity of a switching point of reciprocation in the sub-scanning direction so that the inspection light is projected onto a screen at a position away from a visible region that is visible to a user so that stray light of the inspection light is not visible to the user.

Disclosure of Invention

Problems to be solved by the invention

However, in order to separate the visible region on the screen from the region from which the inspection light is emitted, it is necessary to provide a large invisible region on the screen, which cannot be recognized by the user, and it is necessary to increase the number of screens. Further, increasing the invisible area has a problem that the time taken to scan the visible area is short in the total time of scanning by the scanning unit, and the display efficiency is lowered.

Accordingly, the present invention provides a laser output control device that suppresses a reduction in display quality of stray light, and a laser scanning type display apparatus that employs the laser output control device.

Means for solving the problems

The laser output control device 101 according to embodiment 1 is a laser output control device 101 for adjusting a control value of a light source 11 for displaying an image M by feeding back a light intensity of laser light emitted from the light source 11, the laser output control device 101 including: an illuminance determination unit 21 for obtaining an illuminance signal capable of estimating the illuminance of the surrounding environment or a required luminance signal for controlling the luminance of the image M from the outside and determining the luminance of the surrounding environment; an inspection timing adjusting unit 22 for shortening a period Q during which the light source 11 emits the inspection light Cd, when the illuminance judging unit 21 judges that the ambient environment is dark, as compared with when the ambient environment is bright; and a light source control unit 23 for obtaining a cumulative calculation value Sd of the light intensity of the inspection light Cd emitted from the light source 11 and adjusting the control value for driving the light source 11.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention can inhibit the display quality reduction caused by stray light.

Drawings

Fig. 1 is a view for explaining a mounting manner of a head-up display device according to an embodiment of the present invention;

fig. 2 is a view showing an example of a general configuration cross section of the head-up display device according to the above embodiment;

FIG. 3 is a view showing an example of a cross section of a general structure of the laser output section according to the above embodiment;

fig. 4 is a block diagram illustrating an electrical configuration of the laser output section according to the above embodiment;

fig. 5 is a diagram showing an example of an on-screen scanning mode in the laser scanning type display device of the above embodiment;

fig. 6 (a) is a diagram showing a time transition of the sub-scanning position, fig. 6 (b) is a diagram showing an emission timing of the detection light corresponding to the time transition of fig. 6 (a), and fig. 6 (c) is a diagram showing an example of the detection signal corresponding to the time transition of fig. 6 (a);

fig. 7 (a) is a diagram showing a time transition of the sub-scanning position, fig. 7 (b) is a diagram showing a timing of emitting the detection light when the ambient environment is bright corresponding to the time transition of fig. 7 (a), and fig. 7 (c) is a diagram showing an example of the detection signal when the ambient environment is dark corresponding to the time transition of fig. 7 (a);

fig. 8 is a flowchart showing an example of the light intensity compensation process performed by the control unit in the above embodiment.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments (including the contents of the drawings). Modifications (including deletion of constituent elements) may be made to the embodiments described below. In the following description, descriptions of well-known matters will be omitted as appropriate to facilitate understanding of the present invention.

As shown in fig. 1, a head-up display device (HUD device) 1 according to an embodiment of the present invention is provided on an instrument panel of a vehicle 2, and emits display light K indicating an image M (see fig. 2) for notifying predetermined information toward a windshield (an example of a transmissive/reflective unit) 2 a. The display light K reflected by the windshield 2a is recognized by the observer 3 (mainly, the driver of the vehicle 2) as a virtual image V formed in front of the windshield 2 a.

As shown in fig. 2, the HUD device 1 of fig. 1 includes an image forming unit (laser scanning type display device) 100, a 1 st reflecting unit 200, a 2 nd reflecting unit 300, which are relay optical units that direct display light K of an image M formed by the image forming unit 100 toward a front windshield 2a, a case 400 that accommodates the image forming unit 100, the 1 st reflecting unit 200, the 2 nd reflecting unit 300, and the like, and an external light sensor 500 that detects illuminance outside the HUD device 1.

The 1 st reflection unit (relay optical unit) 200 and the 2 nd reflection unit (relay optical unit) 300 in fig. 2 are configured by, for example, a flat or curved mirror or the like, receive display light K indicating an image M displayed on the screen 103, and reflect the display light K toward the front windshield 2 a. In a typical embodiment, the 2 nd reflecting unit 300 having a concave curved surface has a function of enlarging the image M formed by the image forming unit 100, a function of compensating for the deformation of the windshield 2a and recognizing the virtual image V that is not deformed, a function of forming the virtual image V at a position away from the user by a predetermined distance, and the like. In the present embodiment, the relay optical unit is two reflection type optical members of the 1 st reflection unit 200 and the 2 nd reflection unit 300, but, for example, one of the reflection type relay optical units (the 2 nd reflection unit 300) may be omitted, and another reflection type relay optical unit may be added. The relay optical unit may be a refractive type or a diffractive type such as a lens, or a combination of a refractive type and a diffractive type such as a lens, instead of the reflective type.

The housing 400 accommodates the laser output unit 101, the scanner unit 102, the screen 103, the 1 st reflecting unit 200, the 2 nd reflecting unit 300, and the like, and the housing 400 is made of a light-shielding member, and a light-transmitting portion 410 that transmits the display light K is provided in a part of the housing 400. For example, an external light sensor 500 is provided on the inner surface of the translucent portion 410, and the external light sensor 500 detects the external illuminance of the HUD device 1 and outputs information relating to the external illuminance to the control unit 20.

(image forming section (laser scanning type display device) 100)

The image forming unit 100 forms an image M on a display surface (screen 103) by two-dimensionally scanning laser light. The image forming unit 100 is mainly composed of, for example, a laser output unit 101, a scanning unit 102, and a screen 103, the laser output unit 101 emitting the synthetic laser light C, the scanning unit 102 scanning the synthetic laser light C emitted from the laser output unit 101, and the screen 103 receiving the synthetic laser light C scanned by the scanning unit 102 and displaying the image M.

The laser output unit 101 emits a synthesized laser beam C described later toward the scanning unit 102, and the laser output unit 101 is composed of, for example, a laser output unit 10 and a control unit 20, and the control unit 20 controls the light source 11, the scanning unit 102, and the like provided in the laser output unit 10.

Fig. 3 is a diagram showing a configuration example of the laser output section 10. The laser output unit 10 is mainly composed of a light source 11, a light condensing unit 12, a light synthesizing unit 13, a light adjusting unit 14, a light branching unit 15, a light intensity detecting unit 16, and a control unit (laser output control device) 20.

The light source 11 of fig. 3 includes a plurality of light sources emitting colored light of different colors, and is configured by, for example, a 1 st light source 11a emitting blue laser light B, a 2 nd light source 11B emitting green laser light G, and a 3 rd light source 11c emitting red laser light R. Specifically, the light source 11 can output laser light of a desired light intensity, for example, with a light intensity of 256 gradations for each color, based on a control value determined by the control unit 20 described later.

The light condensing unit 12 in fig. 3 condenses the laser beams B, G, R emitted from the light sources 11a, 11B, and 11c to form condensed light with a small spot size, and for example, the light condensing unit 12 includes a 1 st light condensing unit 12a, a 2 nd light condensing unit 12B, and a 3 rd light condensing unit 12c, the 1 st light condensing unit 12a is located on the optical path of the blue laser beam B emitted from the 1 st light source 11a to condense the blue laser beam B, the 2 nd light condensing unit 12B is located on the optical path of the green laser beam G emitted from the 2 nd light source 11B to condense the green laser beam G, and the 3 rd light condensing unit 12c is located on the optical path of the red laser beam R emitted from the 3 rd light source 11c to condense the red laser beam R.

The light combining unit 13 shown in fig. 3 is configured to align the optical axes of the laser beams B, G, R emitted from the light sources 11a, 11B, and 11C and reaching through the light condensing unit 12 to emit a combined laser beam C, and the light combining unit 13 includes a 1 st light combining unit 13a, a 2 nd light combining unit 13B, and a 3 rd light combining unit 13C, the 1 st light combining unit 13a adjusting the optical axis of the blue laser beam B, the 2 nd light combining unit 13B adjusting the optical axis of the green laser beam G, and the 3 rd light combining unit 13C adjusting the optical axis of the red laser beam R.

The light adjusting section 14 shown in fig. 3 includes, for example, a VA (vertical alignment) type liquid crystal element 14a and two polarizing filters (polarizing plates) 14b and 14C of an absorption type or a reflection type sandwiching the liquid crystal element 14a, and a control section 20 described later drives the liquid crystal element 14a by a Pulse Amplitude Modulation (PAM) method or a Pulse Width Modulation (PWM) method according to a set light adjustment ratio, thereby changing the light transmittance of the composite laser light C passing through the light adjusting section 14 and adjusting (dimming) the composite laser light C input to the light adjusting section 14 to a desired light intensity. The light modulation unit 14 may be disposed not at a position to receive the synthesized laser beam C obtained by synthesizing the laser beams R, G, and B, but on an optical path corresponding to the laser beams R, G, and B before being synthesized by the light synthesis unit 13. The light modulation unit 14 may be formed of a reflective LCoS (Liquid Crystal On Silicon) or the like, instead of a transmissive Liquid Crystal element. The light control unit 14 may set the dimming ratio based on the external illuminance detected by the external light sensor 500, which will be described later, under the control of a light control unit, which is not shown in the figure. Specifically, for example, when the external illuminance is high (bright), the dimming ratio of the dimming unit 14 is set high to display the image M with high luminance, and when the external illuminance is low (dark), the dimming ratio of the dimming unit 14 is set low to display the image M with low luminance. In order to prevent the liquid crystal element from being sintered, the light adjusting unit 14 is preferably driven in such a manner that: the periods during which the same voltage is applied to the positive electrode and the negative electrode are the same. The liquid crystal element 14a and the two polarizing plates 14b and 14C in the light modulation unit 14 may be provided not continuously on the optical path of the combined laser beam C via the liquid crystal element 14a as shown in fig. 3, but may be provided at separate positions. The polarizing plate 14b on the light source 11 side of the liquid crystal element 14a may be omitted. Further, the light adjusting section 14 may be omitted.

The light branching unit 15 shown in fig. 3 is made of a transmissive member having a reflectance of about 5%, for example, and is provided on the optical path of the synthetic laser light C from the light modulation unit 14 to the scanning unit 102, and transmits most of the synthetic laser light C from the light modulation unit 14 as it is, but part of the light is reflected as reflected light C1 in the direction of the light intensity detection unit 16 described later. The light branching unit 15 may direct the transmitted light to the light intensity detection unit 16 and direct the reflected light in the emission direction (the direction of the scanning unit 102).

The light intensity detector 16 shown in fig. 3 is composed of, for example, a photodiode or a color sensor, receives the reflected light C1 reflected by the light branching unit 15, and detects the light intensity of the received reflected light C1. The light intensity detection unit 16 includes an integration circuit, not shown, and outputs a detection signal Sd obtained by integrating the light intensity of the received reflected light C1 to the control unit 20, which will be described later. The light intensity detection unit 16 may have a variable amplifier 16a for amplifying the detection signal Sd at a variable amplification factor with respect to the control unit 20.

Fig. 4 is a block diagram illustrating an electrical configuration of the laser output unit 101 shown in fig. 2. The control unit 20 of the laser output unit 101 is configured by a circuit including at least one semiconductor integrated circuit such as at least one processor (e.g., a Central Processing Unit (CPU)), at least one Application Specific Integrated Circuit (ASIC), and/or at least one Field Programmable Gate Array (FPGA). The at least one processor may realize all or a part of the functions of the illuminance determination section 21, the inspection timing adjustment section 22, the light source control section 23, the door control section 24, the dimming control section that controls the dimming section 14, which is not shown in the drawing, and the control section 20 including the scan control section by reading one or more commands from at least one computer-readable tangible recording medium. Such recording media include any type of magnetic media such as hard disks, any type of optical media such as CDs and DVDs, any type of semiconductor memory such as volatile memory, and nonvolatile memory. Volatile memory includes DRAM and SRAM, and non-volatile memory includes ROM and NVROM. The semiconductor memory includes a semiconductor circuit that forms a part of a circuit together with at least one processor. An ASIC is an integrated circuit cascaded in such a way as to implement all or part of the functional blocks shown in fig. 4, and an FPGA is an integrated circuit designed in such a way as to implement all or part of the functional blocks shown in fig. 4 after manufacturing.

The illuminance determination unit 21 receives the external illuminance (illuminance signal) of the environment in which the HUD device 1 displays the virtual image V (the environment around the HUD device 1), determines the brightness of the surrounding environment, and outputs the determination result to the inspection timing adjustment unit 22. The illuminance determination unit 21 receives an external illuminance from, for example, an external light sensor 500 provided in the HUD device 1, and determines whether the environment in which the virtual image V is displayed is bright or dark based on the external illuminance.

As another embodiment, the illuminance determination unit 21 may analyze the brightness of the captured image obtained by capturing the front side of the vehicle 2 (the traveling direction of the vehicle 2) with a camera provided in the vehicle 2 by inputting the captured image, and determine the brightness of the surrounding environment. That is, the "illuminance signal capable of estimating the brightness of the surrounding environment" described in the claims may include a captured image of the camera. Further, information (illuminance signal) capable of estimating the illuminance of the surrounding environment may be input by vehicle-to-vehicle communication (V2V) and/or road-to-vehicle communication (V2P) using a communication unit (not shown) provided in the vehicle 2. The illuminance determination unit 21 may input a required luminance signal for controlling the luminance of the virtual image V from the ECU 600 of the vehicle 2, and determine the luminance of the surrounding environment based on the input signal. In this case, the illuminance determination unit 21 may determine that the surrounding environment is bright when a high luminance is required by the required luminance signal.

The inspection timing adjusting unit 22 adjusts the period Q for emitting the detection light Cd by controlling the timing (hereinafter also referred to as start timing) ts for starting emission of the detection light Cd from the light source 11 and/or the timing (hereinafter also referred to as end timing) te for ending emission of the detection light Cd from the light source 11 based on the determination result of the illuminance determining unit 21. When the illuminance determination unit 21 determines that the ambient environment is dark, the inspection timing adjustment unit 22 can shorten the period Q during which the light source 11 emits the detection light Cd by delaying the start timing ts of the detection light Cd and/or advancing the end start timing te of the detection light Cd, and when the illuminance determination unit 21 determines that the ambient environment is bright, can lengthen the period Q during which the light source 11 emits the detection light Cd by advancing the start timing ts of the detection light Cd and/or delaying the end start timing ts of the detection light Cd. The inspection timing adjusting unit 22 may adjust the start timing ts and the end start timing ts of the detection light Cd based on a signal indicating the scanning position of the scanning unit 102 obtained from the scanning unit 102 or a scanning control unit, not shown, that controls the scanning unit 102, a timing signal emitted at a timing at a predetermined scanning position, a synchronization signal that synchronizes the scanning position of the scanning unit 102 and the emission timing of the light source 11, which are output from a timing adjusting unit, not shown, as shown, and the like.

The light source control unit 23 causes the light sources 11a, 11b, and 11c to emit laser light of a desired light intensity by reading light source drive data provided for each of the light sources 11a, 11b, and 11c, which emit laser light of different colors, from a storage unit, which is not shown in the figure. The light source driving data is, for example, data in which a current value (an example of a control value) is associated to drive each of the light sources 11a, 11b, and 11c for each of 8-bit 256 gradations. However, even when the light source 11 is driven at the same current value (control value), it is difficult to express a desired gradation due to a characteristic change of the light source 11 and the light control unit 14 with time or a characteristic change caused by a difference in usage environment such as temperature. The image forming unit 100 of the present embodiment performs a light intensity compensation process in which the laser output unit 101 emits inspection light Cd as inspection laser light, and the light source drive data is compensated based on a detection signal Sd relating to the light intensity of the laser light obtained by detecting the inspection light Cd by the light intensity detection unit 16, so that a desired gradation can be expressed by emitting light sources 11 corresponding to light sources 11 of different colors, thereby displaying an image M with a good white balance.

The light source control unit 23 drives the light sources 11a, 11b, and 11c by a high gradation in the light source drive data, and emits the detection inspection light Cd. Specifically, the color gradation may be 90 to 100%. Since the light intensity of the inspection light Cd is detected to be high by using light of a high gradation, a detection Signal from the light intensity detection unit 16 described later becomes large, and an S/N ratio (Signal-to-Noise ratio) which is a ratio of Noise to the detection Signal can be reduced, and light detection with high accuracy is possible. The control unit 20 may have drive data dedicated to the emission of the inspection light Cd in order to cause the light sources 11a, 11b, and 11c to emit the inspection light Cd. The light source control unit 23 may not make the light intensity of the inspection light Cd (control value for emitting the inspection light Cd) the same according to the brightness of the surrounding environment determined by the illuminance determination unit 21. Specifically, the light source control unit 23 may set the light intensity of the inspection light Cd emitted from the light source 11 when the ambient environment is determined to be dark to be lower than the light intensity of the inspection light Cd emitted from the light source 11 when the ambient environment is determined to be bright. Thus, since the inspection light Cd is weakened when the ambient environment is dark, the amount of stray light directed to the observer 3 can be suppressed by diffusion and scattering of the inspection light Cd.

The variable amplifier 16a is provided between the control unit 20 and the light intensity detection unit 16, amplifies a detection signal Sd of the light intensity of the inspection light Cd from the light intensity detection unit 16, and the gain control unit 24 controls the amplification factor (gain ) of the variable amplifier 16 a. The gain control unit 24 may control the amplification factor in accordance with the length of the period Q during which the inspection light Cd is emitted. Specifically, when the period Q during which the inspection light Cd is emitted is short (when the illuminance determining unit 21 determines that the ambient environment is dark), the gain control unit 24 increases the amplification factor, thereby increasing the value of the detection signal Sd input to the control unit 20 even when the period Q during which the inspection light Cd is emitted is short. The gain control unit 24 may set the variable amplifier 16a with an amplification factor inversely proportional to the period Q during which the inspection light Cd is emitted. Thus, even when the periods Q during which the inspection light Cd is emitted are different, the values of the detection signals Sd input to the control unit 20 can be made substantially equal, and even when the periods Q are different, the light intensity compensation process for compensating the light source drive data can be made common, or the variation in the light intensity compensation process due to the difference in the periods Q can be suppressed to a small extent.

The gain control section 24 may change the amplification factor by the dimming factor of the dimming section 14. The light intensity of the inspection light Cd received by the light intensity detection section 16 varies by the dimming ratio of the dimming section 14. When the external illuminance is high (bright), the dimming ratio of the dimming unit 14 is set high in order to display the image M with high luminance. Then, when the outside illuminance is high (bright), the light intensity of the inspection light Cd received by the light intensity detection unit 16 increases. On the other hand, when the external illuminance is low (dark), the dimming ratio of the dimming unit 14 is set low in order to display the image M with low luminance. Then, the light intensity of the inspection light Cd received by the light intensity detection unit 16 is small. In the control unit 20, for example, when the dimming ratio of the dimming unit 14 is set low and the light intensity of the inspection light Cd is small, the gain control unit 24 causes the variable amplifier 16a to appropriately amplify the detection signal input from the light intensity detection unit 16 to the control unit 20. Thus, by the action of the dimming part 14, even when the light intensity of the inspection light Cd is small, the signal intensity can be increased, and highly accurate light intensity detection is possible.

Fig. 5 is a diagram showing an example of a mode in which the scanning unit 102 shown in fig. 2 scans the synthetic laser light C on the screen 103.

The scanning unit 102 receives the synthesized laser light C from the laser output unit 10, and, under the control of a scanning control unit not shown in the figure, scans the received synthesized laser light C on the screen 103 in the main scanning direction X a plurality of times and scans the received synthesized laser light C in the sub-scanning direction Y, as shown in fig. 5, thereby displaying a desired image M on the screen 103.

The screen 103 is configured by, for example, a hologram diffuser, a microlens array, a diffusion plate, or the like, receives the synthetic laser light C scanned by the scanning unit 102 through the rear surface, displays an image M on the front surface side, and reflects the display light K representing the image M from the front surface toward the 1 st reflecting unit 200 (relay optical unit). In the present embodiment, the screen 103 is of a transmission type, but the screen 103 may be of a reflection type.

The screen 103 is divided into an effective display area 103a and non-display areas (103b, 103c, 103d) for example, the effective display region 103a is a region that is smaller than the outer periphery of the screen 103 shown by the thick-line frame in fig. 5 and is visible as a virtual image V by the observer 3 (i.e., a region that is reflected by the 1 st reflection unit 200 and the like and is emitted to the outside as display light K), the non-display regions (103b, 103c, 103d) are regions surrounding the effective display region 103a shown in a coated form in fig. 5, which are regions that are not normally visible to the viewer 3, the non-display area is divided into intermittent non-display areas 103c (left and right areas of the effective display area 103a in fig. 5) which are adjacent to the effective display area 103a in the main scanning direction X and include a turning point of the main scanning of the scanning section 102, and intermittently switched from the effective display area 103a when the main scanning is performed; continuous non-display regions 103b and 103d (upper and lower regions of the effective display region 103a in fig. 5), the continuous non-display regions 103b and 103d including a region adjacent to the effective display region 103a in the sub-scanning direction Y, and the region other than the effective display region 103a is continuously scanned during the main scanning.

Fig. 6 (a) is a diagram showing a transition of time t of the scanning position in the sub-scanning direction Y of the scanning unit 102, fig. 6 (b) is a diagram showing a timing when the light source 11 emits the inspection light Cd, and fig. 6 (c) is a diagram showing a transition of time t of the detection signal Sd output from the light intensity detection unit 16. The scanning section 102 scans the synthetic laser light C from the scanning start position P1 to the scanning end position P4 of the screen 103, and returns to the scanning start position P1 again if the scanning end position P4 is reached. The 1 frame F for forming the image M is divided into an outbound scanning period Fa in which the scanning unit 102 performs sub-scanning in the positive direction of the sub-scanning direction Y and a return scanning period Fb in which the scanning unit 102 performs sub-scanning in the negative direction of the sub-scanning direction Y at a high speed (the speed in the sub-scanning direction Y is faster than the outbound scanning period Fa). That is, 1 frame F is set to be not less than 1/60 seconds (not less than 60 Hz) at the critical fusion frequency at which human beings can recognize flicker, while the scanning position of the scanning unit 102 starts scanning from the scanning start position P1, passes through the display start position P2 and the display end position P3, which are the end portions on the effective display region 103a, and then returns to the scanning start position P1 again after reaching the scanning end position P4.

The inspection timing adjusting unit 22 starts emission of the inspection light Cd from the light source 11 (any one of the light sources 11a, 11b, and 11 c) at a predetermined start timing ts in the continuous non-display region 103d in which the scanning position of the scanning unit 102 is located at the turning point (reciprocating switching point) in the sub-scanning direction Y, and ends emission of the inspection light Cd at an end timing te after a predetermined period Q has elapsed. As shown in fig. 3, the light intensity detection unit 16 detects the reflected light C1 (inspection light Cd) of the combined laser beam C directed to the scanning unit 102, which is not branched to the scanning unit 102, detects the light intensity of the inspection light Cd regardless of the scanning position of the scanning unit 102, and outputs a detection signal Sd, which is an integrated value obtained by time-integrating the light intensity detected by an integrating circuit (not shown), to the control unit 20 (see fig. 6). Further, it is preferable to reset the integral value of the detection signal Sd (to zero the voltage signal) until the new inspection light Cd is detected.

The inspection timing adjusting unit 22 may start the emission of the inspection light Cd before the scanning position of the scanning unit 102 reaches a reciprocating switching position Y4 in the sub-scanning direction Y, which will be described later, and may end the emission of the inspection light Cd after the scanning position reaches the reciprocating switching position Y4. Thus, in the period Q during which the inspection light Cd is emitted, the scanning position of the scanning unit 102 is folded back in the sub-scanning direction Y, and therefore the width of the inspection light Cd scanned on the screen 103 in the sub-scanning direction Y can be reduced. The "width of the inspection light Cd in the sub-scanning direction Y scanned on the screen 103" referred to herein is the length of the sub-scanning direction Y in the region scanned with the inspection light Cd on the screen 103, and when the period Q includes the reciprocating switching position Y4 in the sub-scanning direction Y, the length is any of the length from the start sub-scanning position Yds at which the emission of the inspection light Cd is started to the reciprocating switching position Y4, and the length from the reciprocating switching position Y4 to the end sub-scanning position Yde at which the emission of the inspection light Cd is ended. On the other hand, when the period Q does not include the switching position Y4 for reciprocation in the sub-scanning direction Y, "the width in the sub-scanning direction Y of the inspection light Cd scanned on the screen 103" is a length from the start sub-scanning position Yds at which the emission of the inspection light Cd is started to the end sub-scanning position Yde at which the emission of the inspection light Cd is ended. Accordingly, if the periods Q are the same, the width of the inspection light Cd scanned on the screen 103 in the sub-scanning direction Y can be reduced when the reciprocating switching position Y4 in the sub-scanning direction Y is included in the period Q. In particular, the inspection timing adjusting unit 22 preferably makes the start sub-scanning position Yds at which the emission of the inspection light Cd in the sub-scanning direction Y is started and the end sub-scanning position Yde at which the emission of the inspection light Cd in the sub-scanning direction Y is ended substantially the same. The point that the start sub-scanning position Yds and the end sub-scanning position Yde are substantially the same here means that the difference between the start sub-scanning position Yds and the end sub-scanning position Yde is within 5% of the length of the scanning range Y1 to Y4 in the sub-scanning direction Y. Thereby, the width of the inspection light Cd in the sub-scanning direction Y on the screen 103 can be further reduced.

Fig. 7 (a) is a diagram showing how the period Q during which the light source 11 emits the inspection light Cd changes, fig. 7 (b) is a diagram showing the emission timing of the inspection light Cd when the ambient environment is bright, and fig. 7 (c) is a diagram showing the emission timing of the inspection light Cd when the ambient environment is dark. When the illuminance determination unit 21 determines that the ambient environment is dark, the inspection timing adjustment unit 22 shortens the period Q during which the light source 11 emits the inspection light Cd as compared with the case where the ambient environment is bright (from the period Q1 in fig. 7 b to the period Q2 in fig. 7 c). Specifically, the inspection timing adjustment unit 22 delays the start timing ts of the inspection light Cd (from the start timing ts1 in fig. 7 (b) to the start timing ts2 in fig. 7 (c)), and advances the start timing ts of the inspection light Cd (from the end timing te1 in fig. 7 (b) to the end timing te2 in fig. 7 (c)). In this case, the width in the sub-scanning direction Y of the inspection light Cd scanned on the screen 103 in the case where the ambient environment is dark (the length from the start sub-scanning position Yds to the end sub-scanning position Yde) is shorter than the width in the case where the ambient environment is bright (the length from the start sub-scanning position Yds (the end sub-scanning position Yde1) to the reciprocating switching position Y4). Since the width of the inspection light Cd scanned on the screen 103 in the sub-scanning direction Y is short, the amount of stray light that is emitted toward the observer 3 by the diffusion or scattering of the inspection light Cd scanned on the screen 103 can be suppressed.

In contrast, when the distance H from the boundary (sub-scanning position Y3) in the sub-scanning direction Y of the effective display region 103a to the region where the inspection light Cd is emitted is relatively bright, the distance H1 from the start sub-scanning position Yds1 (end sub-scanning position Yde1) to the display end sub-scanning position Y3 is longer than the distance H2 from the start sub-scanning position Yds2 to the display end sub-scanning position Y3 in the dark. That is, the area irradiated with the inspection light Cd in the dark is separated from the effective display area 103a as compared with the light. Since the irradiation region of the inspection light Cd scanned on the screen 103 is separated from the effective display region 103a, stray light generated by diffusion or scattering of the inspection light Cd scanned on the screen 103 is hard to be directed to the observer 3. Since the inspection timing adjusting unit 22 can reliably extend the distance H between the effective display area 103a and the area irradiated with the inspection light Cd, it is preferable to delay the start timing ts of the inspection light Cd and end the start timing ts of the inspection light Cd earlier as shown in fig. 7 (c). However, the present invention is not limited to this, and the inspection timing adjusting unit 22 may perform a process of delaying the start timing ts of the inspection light Cd and ending any one of the start timings ts of the inspection light Cd early when the illuminance determining unit 21 determines that the ambient environment is dark.

Fig. 8 is a flowchart of the "light intensity compensation process" performed by the image forming unit 100 according to the present embodiment.

In step S1, the illuminance determination unit 21 obtains the external illuminance from the external light sensor 500 provided in the HUD device 1, and determines whether the environment in which the virtual image V is displayed is bright or dark from the external illuminance.

In step S2, the inspection timing adjusting unit 22 delays the start timing ts of the inspection light Cd and/or advances the end start timing ts of the inspection light Cd when the ambient environment is dark, based on the determination result of the illuminance determining unit 21, thereby shortening the period Q during which the inspection light Cd is emitted. The adjustment of the start time ts and the end start time ts by the inspection time adjustment unit 22 may be 2-level adjustment of the brightness of the surrounding environment, or may be 3-level adjustment or more in stages or continuously in accordance with the brightness of the surrounding environment. The inspection timing adjusting unit 22 may read the start timing ts and the end start timing ts from a storage unit not shown in the figure according to the brightness of the surrounding environment, or may calculate the start timing ts and the end start timing ts from the brightness of the surrounding environment.

In step S3, the examination timing adjustment unit 22 determines whether the examination light Cd determined in step S2 is used (or determines whether the scanning position of the scanning unit 102 reaches the start position Pds belonging to the start timing ts). When the start timing ts (start position Pds) of the inspection light Cd cannot be determined (no at step S3), the light source control unit 23 proceeds to step S4 to cause the light source 11 to output the synthetic laser light C for forming the image M, thereby forming the image M in the effective display area 103a of the screen 103.

When the inspection timing adjustment unit 22 determines the start timing ts (start position Pds) of the inspection light Cd (yes at step S3), the light source control unit 23 proceeds to step S5 to start emission of the inspection light Cd from the light source 11 at the start timing ts (start position Pds) determined at step S5.

In step S6, the light source control unit 23 stops the emission of the inspection light Cd after the inspection time adjustment unit 22 emits the inspection light Cd in the period Q between the start time ts and the end time te determined in step S2, and proceeds to step S7. The light source control unit 23 obtains the detection signal Sd of the inspection light Cd from the light intensity detection unit 16 (or the light intensity detection unit 16 with the variable amplifier 16a interposed therebetween), and stores the detection signal Sd in the storage unit. In addition, the gain control unit 24 may change the amplification factor of the variable amplifier 16a in accordance with the period Q during which the inspection light Cd is emitted during the period during which the inspection light Cd is emitted in steps S5 to S6.

In step S8, the light source control unit 23 determines whether or not the detection signals Sd of all the colored lights RGB have been obtained, and if the light source control unit 23 determines that the detection signals Sd of all the colored lights RGB have not been obtained (no in step S8), the process returns to step S3 to detect the light sources 11 of different colored lights. When the light source control unit 23 determines that the detection signal Sd of all the color lights RGB is obtained (yes in step S8), the control unit 20 (light source control unit 23) proceeds to step S9, and performs compensation processing on the light source drive data of the light sources 11a, 11b, and 11c so that an image M suitable for the external illuminance can be displayed with a desired luminance and a desired white balance. Specifically, for example, the light source control unit 23 performs compensation processing on a control value associated with the color gradation of the emission inspection light Cd in the light source drive data on the basis of the detection signal Sd of the inspection light Cd output at a high color gradation of 90 to 100% of the color gradation of the light source drive data. Next, the light source control unit 23 performs compensation processing on the control value associated with another color gradation in accordance with the compensation amount of the control value associated with the color gradation from which the inspection light Cd is emitted. Thereby, new light source driving data is formed. Further, it is preferable that the new and old light source driving data be switched at the timing when the scanning position of the scanning unit 102 is the continuous non-display region 103 d. The light source control unit 23 may detect the light intensity of the inspection light Cd of only 1 gradation level, and may detect the light intensity of the inspection light Cd of a plurality of gradation levels other than the light intensity of the inspection light Cd, and form new light source drive data based on the detection signal Sd of the inspection light Cd for each of the light sources 11a, 11b, and 11 c.

The detection signals Sd based on the light intensity in steps S5 to S7 may be obtained for a plurality of colors for 1 frame F, but preferably, the detection signals Sd are obtained for 1 color at a time.

[ modified examples ]

Further, the present invention is not limited to the above embodiments and drawings. The embodiment and the drawings may be modified (including the deletion of the constituent elements) as appropriate without changing the spirit of the present invention. In the following, an example of a modification is given.

In the above embodiment, the luminance and the white balance of the image M are adjusted by performing the compensation process on the drive of the light sources 11a, 11b, and 11c (light source drive data) based on the detection signal Sd from the light intensity detector 16, but the luminance and the white balance of the image M may be adjusted by performing the compensation process on the drive of the light modulator 14 based on the detection signal Sd from the light intensity detector 16 instead of or in addition to the compensation of the light source drive data.

The light adjusting unit 14 may be disposed not on the optical path of the combined laser beam C but on the optical path corresponding to the combined laser beam B, G, R, and the light adjustment control of the laser beam B, G, R may be performed.

The emission timing of the inspection light Cd may be determined based on information relating to the scanning position from the scanner unit 102, a drive signal for driving the light source 11, or vehicle information input from the vehicle 2 or the timing of inputting an image.

In the above-described embodiment, the light detection is performed while the image M is formed by using the transmissive film (light branching means), but the light intensity detection unit 16 may be provided at a position on the screen 103 where the light intensity of the laser light scanned on the non-display regions (103a, 103b, 103c) which are regions normally invisible to the observer 3 is received. In this case, a light guide portion, not shown, may be provided, which is formed of a light-transmissive resin material or the like, and guides light in a region irradiated with the inspection light Cd to the light intensity detection portion 16.

Description of reference numerals:

reference numeral 1 denotes a HUD device;

reference numeral 3 denotes an observer;

reference numeral 10 denotes a laser emitting section;

reference numeral 11 denotes a light source;

reference numeral 11a denotes a 1 st light source;

reference numeral 11b denotes a 2 nd light source;

reference numeral 11c denotes a 3 rd light source;

reference numeral 12 denotes a light condensing portion;

reference numeral 13 denotes a light combining section;

reference numeral 14 denotes a light adjusting portion;

reference numeral 15 denotes a light branching portion;

reference numeral 16 denotes a light intensity detection section;

reference numeral 16a denotes a variable amplifier;

reference numeral 20 denotes a control section;

reference numeral 21 denotes an illuminance determination section;

reference numeral 22 denotes an inspection timing adjusting unit;

reference numeral 23 denotes a light source control section;

reference numeral 24 denotes a gain control section;

reference numeral 100 denotes an image forming section;

reference numeral 101 denotes a laser output section;

reference numeral 102 denotes a scanning section;

reference numeral 103 denotes a screen;

reference numeral 103a denotes an effective display area;

reference numeral 103b denotes a continuous non-display area;

reference numeral 103c denotes a discontinuous non-display area;

reference numeral 103d denotes a continuous non-display area;

reference numeral 200 denotes a 1 st reflection part;

reference numeral 300 denotes a 2 nd reflecting part;

reference numeral 400 denotes a housing;

reference numeral 410 denotes a light-transmitting portion;

reference numeral 500 denotes an external light sensor;

reference numeral 600 denotes a vehicle ECU;

symbol C denotes a synthetic laser light;

symbol C1 denotes reflected light;

symbol Cd denotes examination light;

symbol F denotes 1 frame;

symbol Fa represents a scanning route-out period;

symbol Fb denotes the scan loop period;

symbol H represents a distance;

symbol H1 represents a distance;

symbol H2 represents a distance;

symbol K denotes display light;

symbol M represents an image;

symbol P1 denotes a scanning start position;

symbol P2 represents a display start position;

symbol P3 represents a display end position;

symbol P4 denotes a scanning end position;

symbol Pds denotes a start position;

symbol Q represents a period;

symbol Q1 denotes a period;

symbol Sd denotes a detection signal;

symbol V represents a virtual image;

symbol X represents a main scanning direction;

symbol Y denotes a sub-scanning direction.