阅读说明：本技术 投影光学系统及其偏色调整方法 (Projection optical system and color cast adjusting method thereof ) 是由 王则钦 杨炳柯 郭祖强 李屹 于 2018-09-03 设计创作，主要内容包括：本发明提供一种投影光学系统及其偏色调整方法,该投影光学系统,包括：光源、光引导装置和光调制器,光引导装置将光源发出的出射光分成多路并分别引导至光调制器；第一光引导装置将出射光分成沿第一光路出射的红色基色光和沿第二光路出射的第二光；第二光引导装置将第二光分成沿第三光路出射的绿色基色光和沿第四光路出射的蓝色基色光；第一、第二和第三光调制器分别置于第一、第三和第四光路上,并对红色、绿色和蓝色基色光进行调制。本发明根据投影系统光源的光谱特性,使红色基色光首先从出射光中分离出来,解决了白场画面偏色的问题,使投影光学系统的颜色均匀性好。(The invention provides a projection optical system and a color cast adjusting method thereof, wherein the projection optical system comprises: the light guide device divides emergent light emitted by the light source into multiple paths and guides the multiple paths of emergent light to the optical modulator respectively; the first light guide device divides the emergent light into red primary light emergent along a first light path and second light emergent along a second light path; the second light guiding device divides the second light into green primary light emitted along a third light path and blue primary light emitted along a fourth light path; first, second and third light modulators are disposed on the first, third and fourth light paths, respectively, and modulate red, green and blue primary light. According to the spectral characteristics of the light source of the projection system, the invention separates the red base color light from the emergent light, solves the problem of white field picture color cast, and ensures that the color uniformity of the projection optical system is good.)

1. A projection optical system comprising: a light source, a light guiding device, a light modulator,

the light source is used for emitting emergent light at least comprising three primary colors;

the light guide device divides the emergent light into multiple paths and guides the emergent light to the light modulators respectively;

the method is characterized in that: the light directing device comprises a first light directing device and a second light directing device, and the light modulators comprise a first light modulator, a second light modulator and a third light modulator;

the first light guide device divides the emergent light into red primary light emergent along a first light path and second light emergent along a second light path, wherein the second light is other primary light except red primary light in the emergent light;

the second light guiding device divides the second light into green primary light emitted along a third light path and blue primary light emitted along a fourth light path;

the first light modulator is arranged on the first light path and modulates the red primary light;

the second light modulator is arranged on the third light path and modulates the green primary light;

and the third light modulator is arranged on the fourth light path and modulates the blue primary color light.

2. The projection optical system according to claim 1, further comprising a first reflection component and a second reflection component;

the first reflection assembly is arranged on the first light path and used for reflecting the red base color light to enable the red base color light to enter the first light modulator;

the second reflection assembly is arranged on the fourth light path and used for reflecting the blue primary color light to enable the blue primary color light to enter the third light modulator.

3. The projection optical system according to claim 1, wherein the first light guiding means includes a first dichroic filter, and the second light guiding means includes a second dichroic filter.

4. The projection optical system according to claim 1, wherein the dichroic wavelength range of the second dichroic filter is 465-495 nm.

5. The projection optical system according to claim 1, wherein the light source further comprises a control device that controls the blue primary color light to enter the third light modulator for modulation while controlling a part of the green primary color light to enter the second light modulator for modulation when modulating a blue image frame.

6. The projection optical system according to claim 5, further comprising a supplemental light source for emitting a green primary light, the part of the green primary light being provided by the supplemental light source.

7. The projection optical system according to claim 5, wherein, when modulating the blue image frame, the range of ratios of the gray-scale values of the blue primary light and the green primary light is: 100 to 255.

8. The projection optical system according to claim 6, wherein the control means controls the green primary light emitted from the light source and the green primary light emitted from the supplemental light source to enter the second light modulator for modulation when modulating a green image frame.

9. A method of adjusting color shift of a projection optical system according to any one of claims 1 to 8, comprising the steps of:

step 100: the emergent light which is emitted by the light source and at least comprises three primary colors is sequentially divided into red primary color light, green primary color light and blue primary color light which are emitted along different light paths under the action of the light guide device;

step 200: the red, green and blue primary color lights are respectively modulated by the first, second and third light modulators and then converged and emitted through the light-combining prism, wherein the light path through which the blue primary color light passes is longest before entering the light modulators.

10. The method for adjusting color cast of a projection optical system as claimed in claim 9, wherein the step 100 comprises:

the light directing means comprises first and second light directing means;

the optical modulators include a first optical modulator, a second optical modulator, and a third optical modulator;

the first light guide device divides the emergent light into red primary light emergent along a first light path and second light emergent along a second light path, wherein the second light is other primary light except red primary light in the emergent light;

the second light guide device divides the second light into green primary light emitted along a second light path and blue primary light emitted along a third light path;

the first light modulator is arranged on the first light path and used for modulating the red primary light;

the second light modulator is arranged on the second light path and used for modulating the green primary light;

and the third light modulator is arranged on the third light path and modulates the blue primary color light.

Technical Field

The invention relates to the technical field of optics, in particular to the technical field of projection and illumination, and discloses a projection optical system with good color uniformity and a color cast adjusting method thereof, and particularly relates to a projection optical system and a color cast adjusting method thereof.

Background

In the existing projection optical system, a light source emits white illumination light, the white illumination light enters an optical-mechanical system and is divided into R, G, B three-color light by a dichroic sheet, the three-color light is respectively illuminated on a spatial light modulator, and an image is obtained after passing through a light combining device and a lens.

Since the dichroic sheet is capable of reflecting light of a certain wavelength and transmitting light of another wavelength, light of different wavelengths is separated. The dichroic film is generally coated in the prior art to have the light splitting capability. Due to the characteristics of the coating, when the incident angle of the light beam is different, the transmission/reflection spectrum characteristics of the dichroic filter to the light beam also change, and the general rule is that the incident angle of the light beam is larger, and the transmission/reflection spectrum line of the dichroic filter shifts to the short wave direction.

In general, when the main optical axis of a light beam emitted from an object plane is incident on an image plane in parallel in an optical path, the optical path is called a telecentric optical path; if the light is not incident on the image plane in parallel, the light is called a non-telecentric light path. In a projection optical system, when a dichroic sheet is placed in a non-telecentric illumination light path, there may be a difference in transmission/reflection spectra of different regions due to different incident angles of light beams in the different regions, and when the light source spectrum is wide, the spectral components of light transmitted/reflected by the different regions of the dichroic sheet may be different, resulting in color inconsistency on both sides of a picture. Such as: if a typical three-LCD projection system is taken as an example, when a white field picture is projected, the picture will have the problem of being greenish on the left side and reddish on the right side.

The existing projection light sources can be mainly classified into bulb light sources such as xenon lamps and UHP lamps (ultra-high pressure mercury bulbs), LED light sources, pure laser light sources and laser fluorescent light sources. Fig. 1 to 4 are emission spectra of a conventional bulb light source 1000, an LED light source, a pure laser light source, and a laser fluorescence light source 9000, respectively, and their emission spectra are shown in fig. 1 to 4. It should be noted that, as shown in fig. 3, whether the blue laser light source 6000, the green laser light source 7000, or the red laser light source 8000 is used, the spectrum of the pure laser light source is narrow, which is not in the discussion of the problem to be solved by the present invention. The light source 1000 of the bulb shown in fig. 1, the blue LED light source 2000, the green LED light source 3000, the red LED light source 4000, the converted green LED light source 5000 shown in fig. 2, and the laser fluorescent light source 9000 shown in fig. 4 have a relatively wide emission spectrum, and have spectral components at spectral positions where the transmittance/reflectance of the dichroic filter changes, so that when applied to the projection optical system according to the present invention, an unavoidable problem of color shift of a picture may occur.

In the actual use of the projection system, the problem of color cast usually has no perceptible effect in the process of playing video, but the problem is particularly obvious for the use scenes mainly including white pictures, such as office work, teaching and the like.

In general, in the design of such an optical system, the problem is corrected by gradient coating of the dichroic plates, namely: different areas of the dichroic plate are coated with films of different characteristics to correct for the effects of different incident angles. In practical production, due to the influence of tolerance, the gradient coating is difficult to accurately compensate for color shift caused by different incident angles, so that the projection system of this type cannot avoid slight color shift problem. Meanwhile, the cost of the dichroic film coated by the gradient coating is improved, and the more accurate the gradient of the dichroic film is changed, the higher the cost is.

Disclosure of Invention

The invention aims to solve the technical problem of providing a projection optical system and a color cast adjusting method thereof aiming at the defects of the prior art.

The technical problem to be solved by the invention is realized by the following technical scheme:

a projection optical system comprising: a light source, a light guiding device, a light modulator,

the light source is used for emitting emergent light at least comprising three primary colors;

the light guide device divides emergent light into multiple paths and guides the emergent light to the light modulator respectively;

the light directing device comprises a first light directing device and a second light directing device, and the light modulators comprise a first light modulator, a second light modulator and a third light modulator;

the first light guide device divides the emergent light into red primary light emergent along a first light path and second light emergent along a second light path, wherein the second light is other primary light except red primary light in the emergent light;

the second light guiding device divides the second light into green primary light emitted along a third light path and blue primary light emitted along a fourth light path;

the first light modulator is arranged on the first light path and modulates the red primary light;

the second light modulator is arranged on the third light path and modulates the green primary light;

and the third light modulator is arranged on the fourth light path and modulates the blue primary light.

The invention also provides a color cast adjusting method of the projection optical system, which comprises the following steps:

step 100: the emergent light which is emitted by the light source and at least comprises three primary colors is sequentially divided into red primary color light, green primary color light and blue primary color light which are emitted along different light paths under the action of the light guide device;

step 200: the red, green and blue primary color lights are respectively modulated by the first, second and third light modulators and then converged and emitted through the light-combining prism, wherein the light path through which the blue primary color light passes is longest before entering the light modulators.

In summary, the present invention provides a projection optical system and a color shift adjusting method thereof, according to the spectral characteristics of a light source of the projection system, when the emergent light including three primary colors passes through a first light guiding device, the red primary color light is firstly separated from the emergent light, and before the three primary color light enters an optical modulator, the light path through which the blue primary color light passes is longest, so that the directions of a red primary color picture and a green primary color picture are consistent, the problem of color shift of a white field picture is solved, and the color uniformity of the projection optical system is good; when the blue image frame is modulated, the blue primary color light is supplemented with the green primary color light, so that the color of a blue display picture is improved, and a better display effect is obtained.

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Drawings

FIG. 1 is a diagram of the emission spectrum of a conventional bulb light source;

FIG. 2 is a diagram of a conventional LED light source;

FIG. 3 is a diagram of the emission spectrum of a conventional pure laser light source;

FIG. 4 is a diagram of the luminescence spectrum of a conventional laser fluorescence light source;

FIG. 5 is a schematic view of a projection optical system according to the present invention;

FIG. 6 is a plot of the emission source spectrum versus the projection spectrum for the system of FIG. 5.

Description of the reference numerals

201 positive lens 202 first dichroic filter 203 second dichroic filter 204 first relay lens 205 mirror 206 second relay lens 207 field lens 208 spatial light modulator 209 x-cube

1000 bulb light source 2000 blue LED light source 3000 green LED light source 4000 red LED light source 5000 converted green LED light source 6000 blue laser light source 7000 green laser light source 8000 red laser light source 9000 laser fluorescence light source

Detailed Description

In general, the present invention provides a projection optical system comprising: the device comprises a light source, a light guiding device and a light modulator, wherein the light source is used for emitting emergent light at least comprising three primary colors of red, green and blue; the light guide device divides the emergent light into multiple paths and guides the emergent light to the light modulators respectively; the light directing device includes a first light directing device and a second light directing device, and the light modulators include a first light modulator, a second light modulator, and a third light modulator. Specifically, the first light guiding device divides the outgoing light into red primary light outgoing along a first light path and second light outgoing along a second light path, the second light being other primary light except for red primary light in the outgoing light; the second light guiding device divides the second light into green primary light emitted along a third light path and blue primary light emitted along a fourth light path; the first light modulator is arranged on the first light path and modulates the red primary light; the second light modulator is arranged on the third light path and modulates the green primary light; and the third light modulator is arranged on the fourth light path and modulates the blue primary color light.

In order to ensure that the red, green and blue primary color lights respectively enter the corresponding light modulators and ensure that the light path through which each primary color light passes is better, the projection optical system further comprises at least two reflection assemblies, namely a first reflection assembly and a second reflection assembly, wherein each reflection assembly can comprise one, two, three or more reflectors; the first reflection assembly is arranged on the first light path and used for reflecting the red base color light to enable the red base color light to enter the first light modulator; the second reflection assembly is arranged on the fourth light path and used for reflecting the blue primary color light to enable the blue primary color light to enter the third light modulator.

More specifically, the first light directing arrangement comprises a first dichroic filter and the second light directing arrangement comprises a second dichroic filter.

In order to achieve better display effect, the filter cut-off range of the second dichroic filter is 465-495nm range segments, that is, the color separation wavelength range of the second dichroic filter is 465-495 nm. Referring to fig. 6, T2 is the transmission line of the second dichroic plate, and light in the wavelength range less than 465nm can be totally transmitted through the second dichroic plate, and light in the wavelength range more than 495nm can be totally reflected by the second dichroic plate. Preferably, the dichroic wavelength range of the second dichroic filter is 475-485 nm.