CN113900323A - Single-plate type liquid crystal projection device - Google Patents
Single-plate type liquid crystal projection device Download PDFInfo
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- CN113900323A CN113900323A CN202111126806.1A CN202111126806A CN113900323A CN 113900323 A CN113900323 A CN 113900323A CN 202111126806 A CN202111126806 A CN 202111126806A CN 113900323 A CN113900323 A CN 113900323A
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/005—Projectors using an electronic spatial light modulator but not peculiar thereto
- G03B21/006—Projectors using an electronic spatial light modulator but not peculiar thereto using LCD's
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/2006—Lamp housings characterised by the light source
- G03B21/2013—Plural light sources
Abstract
The invention protects a single-plate type liquid crystal projector, which comprises an illumination light source and a liquid crystal modulator, wherein the liquid crystal modulator comprises a liquid crystal modulation layer and a color film, and illumination light emitted by the illumination light source is modulated by the liquid crystal modulation layer and filtered by the color film to form color image light emission; the color signal processing module is used for respectively outputting an illumination light source control signal and an optimized image signal to the illumination light source driving module and the liquid crystal modulator according to the original image signal; the illumination light source driving module independently controls the luminous flux of at least two color lights contained in the illumination light according to the illumination light source control signal, so that the illumination light source emits optimized illumination light; the optimized illumination light is modulated by the liquid crystal modulator according to the optimized image signal and forms optimized color image light after color film filtering, the color domain of the optimized color image light is enlarged compared with the original color image light, and the illumination intensity is improved compared with the ideal color image light, so that the single-plate liquid crystal projection device has both brightness and color.
Description
Technical Field
The invention relates to the technical field of projection display, in particular to a single-plate type liquid crystal projection device.
Background
In recent years, in the field of projection products, the cost and technical threshold of projectors are gradually reduced along with the replacement of bulb light sources by LED light sources. Moreover, with the popularization of laser televisions and intelligent micro-projection in recent years, the acceptance of people to the product form of the household display equipment is gradually improved, and the household projection market is increased explosively.
In the prior art, as a core device of projection display, a display chip occupies most profits of projection products. In order to reduce the product cost, the LCD panel originally used for products such as a mobile phone display screen is used in a projection product as a display chip in the prior art. The LCD panel is provided with a pixel-level color film at the emergent end, and when white light is transmitted from the LCD panel, the color film is used for filtering the white light into R, G, B colors at different pixel positions, so that an image of a color pixel array is formed, and therefore, the projection product architecture only needs one LCD panel. Since the LCD panel has low light transmittance and large light loss, manufacturers usually select a color film with a wide spectrum to reduce the light flux filtered by the color film in order to increase the total light flux of the projection product. This results in pixels of one color leaking light of other colors (referred to herein as crosstalk leakage), for example: in a pure blue field, green light leaks out of the color film, so that the blue color is greenish; for a pure green field, more blue and red light will leak out. Therefore, LCD projection of such single panel architecture is often difficult to achieve the color gamut like rec.709, and the color performance is poor, so that this kind of product may be considered as being equal to the low-end product.
However, the low cost does not mean the low end of the product and the technology is behind, and a single-plate LCD projection technical scheme which can give consideration to both brightness and color is needed to prove the image and value of the technical scheme architecture.
Disclosure of Invention
In order to solve the defect that a single-plate liquid crystal projection device in the prior art cannot meet the color requirement while pursuing brightness, the invention discloses a single-plate liquid crystal projection device which comprises an illumination light source and a liquid crystal modulator, wherein the liquid crystal modulator comprises a liquid crystal modulation layer and a color film, and illumination light emitted by the illumination light source is modulated by the liquid crystal modulation layer and filtered by the color film to form color image light to be emitted; the color signal processing module is used for respectively outputting an illumination light source control signal and an optimized image signal to the illumination light source driving module and the liquid crystal modulator according to the original image signal for at least part of the original image signal; the illumination light source driving module is used for independently controlling the luminous fluxes of at least two color lights contained in the illumination light according to the illumination light source control signal so as to enable the illumination light source to emit optimized illumination light; the optimized illumination light is modulated by the liquid crystal modulation layer according to the optimized image signal and filtered by the color film to form optimized color image light for emission; the method comprises the steps that color image light formed by modulating illumination light in a full white field image signal through a liquid crystal modulation layer according to an original image signal and filtering the illumination light through a color film is original color image light, and the original color image light in the case of not considering crosstalk leakage of the color film is defined as ideal color image light; the color gamut of the optimized color image light is larger than the original color image light, and the illuminance of the optimized color image light is larger than the ideal color image light.
In the invention, the luminous fluxes of different color lights contained in the illumination light output by the illumination light source can be independently controlled, taking a sub-pixel corresponding to a color as an example, by controlling the luminous flux ratio of one color light to another color light in the illumination light output by the illumination light source, the color coordinate of the light passing through the sub-pixel can be controlled, and by simultaneously controlling the image signal input to the liquid crystal modulator, the absolute luminous flux of the light passing through the sub-pixel can be controlled, so that the illumination light source control signal and the optimized image signal are output under the constraint condition that the optimized color image light is larger than the ideal color image light and the color gamut is enlarged to be the signal processed by the color signal processing module, and finally, the image light with large illumination and enlarged color gamut is obtained, thereby the single-plate type liquid crystal projection device simultaneously takes account of brightness and color.
In one embodiment of the present invention, the illumination light source at least includes a red solid state light emitting device, a green solid state light emitting device, and a blue solid state light emitting device, which are independently controllable, the color film at least includes a red pixel filter region, a green pixel filter region, and a blue pixel filter region, and any pixel at least includes three sub-pixels respectively located in the corresponding red pixel filter region, green pixel filter region, and blue pixel filter region; the red pixel filter region transmits at least part of light emitted by the green solid state light-emitting element and/or the blue solid state light-emitting element, the green pixel filter region transmits at least part of light emitted by the red solid state light-emitting element and/or the blue solid state light-emitting element, and the blue pixel filter region transmits at least part of light emitted by the green solid state light-emitting element and/or the red solid state light-emitting element.
In one embodiment of the present invention, the illumination light source driving module simultaneously drives the red solid state light emitting element, the green solid state light emitting element, and the blue solid state light emitting element according to the illumination light source control signal.
In one embodiment of the present invention, for an arbitrary image signal, in the red solid state light emitting element, the green solid state light emitting element, and the blue solid state light emitting element, there is at least one of the same output power as it is at the time of the full white field image signal.
In one embodiment of the present invention, the color signal processing module determines a solid-state light emitting element having the same output power as that at the time of the full white-field image signal from the sub-pixel having the largest gray-scale value in the original image signal.
In one embodiment of the invention, for the same frame of image, the gray-scale value of any pixel in the optimized image signal is not less than the gray-scale value of the pixel in the original image signal.
In one embodiment of the invention, the optimized illumination light has a luminous flux of at least one color light that is lower than the luminous flux of the illumination light at the time of the full white image signal.
In one embodiment of the present invention, the light from the red solid state light emitting elements exiting from the red pixel filter region in the optimized color image light and the light from the red solid state light emitting elements exiting from the red pixel filter region in the original color image light have the same luminous flux for any pixel.
In one embodiment of the present invention, when the original image signal is a primary color pure color image signal, only the solid-state light-emitting elements of the illumination light source corresponding to the primary color are turned on.
In one embodiment of the present invention, the liquid crystal modulator emits light of an original color image when a sub-pixel having a maximum gray-scale value in an original image signal belongs to a white pixel.
Drawings
FIG. 1 is a functional block diagram of a single-panel liquid crystal projector according to the present invention;
FIG. 2 is a diagram of an optical path structure of a single-plate liquid crystal projector according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of the color film in fig. 2;
FIG. 4 is a light source spectrum diagram of the single-plate liquid crystal projector of FIG. 2;
FIG. 5 is a color filter profile of the single panel liquid crystal projector of FIG. 2;
fig. 6 is an example of drive control of the single-plate type liquid crystal projector apparatus of the present invention.
Detailed Description
The invention mainly aims to control the color coordinate of light by independently adjusting the absolute brightness and relative proportion of different color lights of the illumination light source, and compensate the influence of adjusting the absolute brightness of color light by adjusting the light transmittance of each sub-pixel of the liquid crystal modulator, thereby improving the color of image light while basically not influencing the output illumination of the image light.
The following examples are further illustrative and supplementary to the present invention and do not limit the present invention in any way.
Referring to fig. 1, a functional block diagram of a single-plate liquid crystal projector according to the present invention is shown, wherein the single-plate liquid crystal projector includes an illumination light source, a liquid crystal modulator, a color signal processing module, an illumination light source driving module, and an imaging module.
From the perspective of optical signals, the illuminating light emitted by the illuminating light source forms color image light after passing through the liquid crystal modulator, and then is projected and imaged at a preset position through the imaging module. The liquid crystal modulator comprises a liquid crystal modulation layer and a color film, wherein the liquid crystal modulation layer modulates the illumination light, and the color film further filters emergent light of the liquid crystal modulation layer, so that colored image light is obtained.
From the perspective of electrical signals, the signals can be divided into at least video signals and control signals, and the color signal processing module receives the original image signals (video signals) and judges whether optimization processing is needed. For at least part of the original image signals, the color signal processing module judges that the original image signals need to be optimized, and respectively outputs an illumination light source control signal to the illumination light source driving module and outputs an optimized image signal (video signal) to the liquid crystal modulator according to the original image signals. The illumination light source driving module controls the output power of the illumination light source according to the illumination light source control signal, and in the invention, the light emitting modules emitting different color lights in the illumination light source can be independently controlled, so that the luminous flux of the different color lights contained in the illumination light can be independently controlled, and the optimized illumination light (light signal) can be obtained. And the optimized illumination light is modulated by the liquid crystal modulation layer according to the optimized image signal and filtered by the color film to form optimized color image light for emission.
For the original image signal which does not need to be optimized, the original image signal is directly output to the liquid crystal modulator, and the illumination light source driving module drives the illumination light source to output at the rated power. When the original image signal is a full-white-field image signal, the illumination intensity of emergent light of the projection device is the maximum, at the moment, the transmittance of each sub-pixel of the liquid crystal modulation layer is the maximum, and the output power of the emergent light of the illumination light source is the rated power. Therefore, the illumination light in the case of the full white image signal may also be referred to as the original illumination light, i.e., the illumination light that is not optimized (the light flux of at least one color light is reduced).
Defining the original color image light as the original illumination light (or the illumination light when the original image signal is full white) modulated by the liquid crystal modulation layer according to the original image signal and filtered by the color film; meanwhile, the original color image light when the color film crosstalk leakage is not considered is defined as ideal color image light (that is, only the red sub-pixel is considered to transmit only the emergent light of the red light emitting element, the green sub-pixel is considered to transmit only the emergent light of the green light emitting element, and the blue sub-pixel is considered to transmit only the emergent light of the blue light emitting element). In the present invention, the image signal and the output light of the illumination light source are optimized in the following rules: for the same image signal, the color gamut of the optimized color image light is larger than that of the original color image light, and the illumination of the optimized color image light is larger than that of the ideal color image light, so that the brightness and the color are considered at the same time.
In fig. 1, the illumination light source includes three color light sources of red (R), green (G), and blue (B) that can be independently controlled, and when an original image signal is a color image with a high red luminance, the output power of the red light source can be controlled to maintain a rated power, and the output powers of the blue light source and the green light source are reduced, so as to reduce the amount of blue-green light that is leaked from a color filter region corresponding to a red sub-pixel by crosstalk, and simultaneously, the gray-scale values of the blue sub-pixel and the green sub-pixel are integrally increased (that is, the light transmittances of the liquid crystal modulation layers corresponding to the blue sub-pixel and the green sub-pixel are increased) by optimizing the image signal, so that the luminous flux of the corresponding color light emitted by the blue/green sub-pixel is maintained unchanged, the overall illuminance is ensured to be substantially unchanged, and the color display effect is optimized to a certain extent.
Referring to fig. 2, which is a structure diagram of an optical path of a single-plate liquid crystal projection apparatus according to an embodiment of the present invention, a single-plate liquid crystal projection apparatus 100 includes an illumination light source 110, a liquid crystal modulator 120, and an imaging module 130, and further includes a series of optical system elements disposed on the optical path of the illumination light source 110.
The illumination light source 110 includes a red solid-state light emitting element 111, a green solid-state light emitting element 112, and a blue solid-state light emitting element 113 that can be controlled independently, and these solid-state light emitting elements may be LEDs, and in some embodiments, may also be light emitting devices such as LDs, VCSELs, etc., and have the following common characteristics: the light emitting elements of different colors can be controlled independently.
In the present embodiment, the red solid-state light emitting element 111, the green solid-state light emitting element 112, and the blue solid-state light emitting element 113 combine and homogenize light through one tapered integrating rod 140, so as to mix and form uniform mixed light, and the uniform mixed light exits from the exit end of the tapered integrating rod 140, and the tapered integrating rod 140 functions as both a light combining device and a light homogenizing device. In other embodiments of the present invention, the red, green, and blue lights may be combined by combining wavelengths, for example, by an X-cube, and further an optical device such as a fly-eye lens may be used to homogenize the lights, which is not described herein again.
The homogenized illumination light passes through an optical device such as a lens and enters the light incident surface of the liquid crystal modulator 120. The liquid crystal modulator 120 includes a polarizer 123, a liquid crystal modulation layer 121, a color film 122, and an analyzer 124 sequentially disposed along an optical path. The polarizer 123 is configured to polarize the illumination light, so that the light passing through the polarizer 123 is linearly polarized light in a single polarization state, the liquid crystal modulation layer 121 is configured to adjust and change the polarization state of the linearly polarized light according to a voltage applied to each pixel, the color film 122 is configured to filter light passing through pixel regions of different colors, and the analyzer 124 is configured to select the polarization state of the modulated light, and only passes through light in a preset polarization state.
Referring to fig. 3, a schematic structural diagram of the color film 122 at least includes a red pixel filter area (denoted as R in the figure), a green pixel filter area (denoted as G in the figure), and a blue pixel filter area (denoted as B in the figure), taking an arbitrary pixel 1221 as an example (here, the pixels of the color film correspond to the pixels of the liquid crystal modulator 120 one by one, and therefore, the pixels of the color film are taken as an example for description), where the pixel 1221 at least includes three sub-pixels respectively located in the red pixel filter area 1221R, the green pixel filter area 1221G, and the blue pixel filter area 1221B. When the illumination light is incident on the pixel 1221, at least a portion of the green light component and the blue light component passing through the red pixel filter area 1221R are filtered, and meanwhile, in view of improving the overall brightness of the projection apparatus, the red pixel filter area 1221R also transmits a portion of the light emitted from the green solid state light emitting device and/or the blue solid state light emitting device. Similarly, the green pixel filter region also transmits part of light emitted by the red solid-state light-emitting element and/or the blue solid-state light-emitting element; the blue pixel filter region also transmits part of light emitted by the green solid-state light-emitting element and/or the red solid-state light-emitting element. The light emitted from the three sub-pixels collectively constitutes the brightness and color of the pixel 1221, and is reflected in the projection image.
Referring to fig. 2 again, after the liquid crystal modulation layer 121 of the liquid crystal modulator 120 modulates, the color film 122 filters, and the analyzer 124 performs polarization selection, the illumination light forms color image light, and the color image light is collected by a lens and projected by the imaging module 130 to form an image, so as to form a color projection image in a predetermined setting. The imaging module 130 may be a projection lens group including a plurality of lenses.
In this embodiment, the illumination source driving module drives the red solid state light emitting device 111, the green solid state light emitting device 112, and the blue solid state light emitting device 113 simultaneously according to the illumination source control signal, and controls the brightness and color of each pixel in cooperation with the modulation of each color sub-pixel by the liquid crystal modulator 120. It will be appreciated that in other embodiments of the invention, it is also possible to control only the emission of two solid state light emitting elements, for example only the green and red solid state light emitting elements, and to improve the color to some extent, the technical principles used being coupled. The control driving principle of the present invention will be further explained below.
Referring to fig. 4 and 5, fig. 4 is a light source spectrum diagram of the single-plate liquid crystal projector according to the embodiment of fig. 2 of the present invention, and fig. 5 is a color filter spectrum diagram of the single-plate liquid crystal projector according to the embodiment of fig. 2 of the present invention. In fig. 4, a solid line (Normalized Spectrum) is a Spectrum curve of the illumination light source when the original image signal is a full-white field signal, and may be regarded as a combined light Spectrum at the rated power of the red, green, and blue solid-state light emitting elements. In fig. 5, the filtering curves of the red pixel filter area R, the green pixel filter area G and the blue pixel filter area B are respectively shown in the three curves of R/G/B in the figure, and it can be seen that, in the actual coating filtering curve, the spectral transmittance is not as ideal as that in theory, the filtering curve of the red pixel filter area R can transmit a small amount of blue light/green light, the filtering curve of the blue pixel filter area B can transmit a small amount of red light/green light, and the filtering curve of the green pixel filter area G can transmit a small amount of red light/blue light. The three dashed lines R/G/B in fig. 4 correspond to the red, green, and blue spectral curves of the normalized spectrum of the solid line illuminating light after being filtered by each filter region in fig. 5, i.e., the spectral curves of "red", "green", and "blue" lights when there is color filter crosstalk leakage. It can be seen that crosstalk leakage of the color film causes a small amount of blue light components to be contained in the "red light", some blue light components and red light components to be contained in the "green light", and a small amount of green light components to be contained in the "blue light". Even if the red, green and blue LEDs are independently turned on and the corresponding chromaticity points can cover the rec.709 color gamut, the color gamut of the emergent light of the final projection device is greatly reduced due to crosstalk leakage of the color film after passing through the liquid crystal modulator.
In the invention, a variable of light source modulation is introduced, and the adverse effect of crosstalk light leakage of a color film is reduced by simultaneously changing the output of the light source and the image light transmittance of the liquid crystal modulation layer under the condition of keeping the emergent light brightness unchanged basically. This is illustrated by a simple data model.
Referring to fig. 6, a color pixel is taken as an example to be described, the color pixel includes three RGB sub-pixels, the illumination light source 110 including an RGB three-color solid-state light emitting element can independently adjust light fluxes output by RGB, the emergent light is uniformly mixed and then enters each sub-pixel of the liquid crystal modulation layer 121 of the liquid crystal modulator, different sub-pixels adjust orientations of liquid crystal molecules according to image data, so as to change polarization state distribution of light, and with the light of the polarization state emitted through the analyzer as a reference, it is considered that the transmittance of the emergent light is modulated by the liquid crystal modulation layer 121, and then the light is filtered by the color film 122 and then emitted. After the light corresponding to the three RGB sub-pixels is filtered by the corresponding red, green and blue pixel filter regions, the mixed emergent light is the emergent light of the pixel, and the color coordinate of the emergent light represents the color of the pixel.
In fig. 6, (a) represents an ideal case without considering crosstalk light leakage of the color filter, the red/green/blue pixel filter region transmits only 100% of the light emitted from the red/green/blue solid-state light emitting device, and the transmittance for the other two color lights is 0%; (b) and (c) the case of crosstalk light leakage of the color filter is considered, here, for convenience of explaining the technical principle, the filter characteristic of the color filter is simplified, and the model sets the red light transmittance of the red pixel filter region to be 100%, and the blue light transmittance and the green light transmittance to be 10%; the green light transmittance of the green pixel light filtering area is 100 percent, and the blue light transmittance and the red light transmittance are 10 percent; the red light transmittance and the green light transmittance of the blue pixel light filtering area are respectively 100% and 10%. Wherein (a) the graph represents the case of ideal color image light; (b) the diagram represents the case of original color image light, without optimal driving modulation of the illumination source 110, the liquid crystal modulation layer 121 is directly modulated according to the original image signal; (c) the figure represents the case of optimizing color image light according to the present invention, and the illumination light source is optimally driven by a control signal to emit optimized illumination light, and the liquid crystal modulation layer 121 is modulated according to the optimized image signal.
In fig. 6, the color and brightness of the original image signal corresponding to the pixel are represented as (0.7R +0.3G +0.2B), and ideally, as shown in fig. 6(a), the RGB solid-state light emitting devices output at rated power, the polarization transmittances of R, G, B sub-pixels of the liquid crystal modulation layer 121 are adjusted to 70%, 30% and 20%, respectively, the blue-green light passing through the liquid crystal modulation layer 121 corresponding to the R sub-pixel is completely blocked in the red pixel filter region, and the red light is transmitted by 100%, so that the ideal color and brightness can be obtained.
In the case of fig. 6(B), the light path before the color filter is the same as that in fig. 6(a), mainly the characteristics of the color filter are different, the red pixel filter region can still transmit 10% of blue light and 10% of green light, the green pixel filter region can still transmit 10% of blue light and 10% of red light, the blue pixel filter region can still transmit 10% of red light and 10% of green light, so the actual emergent light of the red sub-pixel after passing through the color filter is 0.7R +0.07G +0.07B, the actual emergent light of the green sub-pixel is 0.3G +0.03R +0.03B, the actual emergent light of the red sub-pixel is 0.2B +0.02G +0.02R, the color and luminance of the pixel are (0.75R +0.39G +0.3B), although the luminous flux of (0.05R +0.09G +0.1B) is increased compared with the case of fig. 6(a), but the color coordinates are deviated.
In the case of fig. 6(c), the illumination light source control signal and the optimized image signal are respectively output to the illumination light source driving module and the liquid crystal modulator according to the original image signal, the luminous fluxes of the outputs of the green solid state light emitting element and the blue solid state light emitting element are adjusted down to 50%, and the polarization transmittance of the corresponding sub-pixels is increased by one time (the transmittance of the G sub-pixel is adjusted from 30% to 60%, and the transmittance of the B sub-pixel is adjusted from 20% to 40%), so that the luminous flux of the corresponding color light output by each sub-pixel before the color filter is maintained unchanged (the red light emitted by the R sub-pixel is unchanged, the green light output by the G sub-pixel is unchanged, and the blue light output by the B sub-pixel is unchanged), considering the color filter characteristic same as that of fig. 6(B), the actual output light of the red sub-pixel is 0.7R +0.035G +0.035B, the actual output light of the green sub-pixel is 0.3G +0.06R +0.03B, the actual output light of the blue sub-pixel is 0.2B +0.04R +0.02G, the color and brightness of the combined output light of the pixel is (0.8R +0.355G +0.265B), which is increased by (0.1R +0.055G +0.065B) compared with fig. 6(a) in the ideal case, and on the one hand, the brightness is increased to some extent, and on the other hand, the deviation of the color coordinate is better compared with the case of fig. 6 (B). Specifically, originally, the pixel has a high red color ratio, the red light ratio of the light leaked in fig. 6(b) is small, and the red light ratio of the light leaked in fig. 6(c) after optimization is large, so the color coordinate of the optimized case in fig. 6(c) is better.
More generally, RGB three color LEDs are defined at current IiThe luminances under the conditions of (i ═ R, G, B) were Li(Ii) (i ═ R, G, B). For a pixel, which includes RGB sub-pixels, an illumination light L is definediThe transmittance of a color film corresponding to a sub-pixel transmitting j (j ═ R, G, B) is τij. Let the transmittance of the sub-pixel j and its gray level s be assumedj∈[0，1]In a linear relationship, so that the illumination light LiThe transmission gray scale is sjHas a luminance of Li·τij·sj. Tau is caused by light leakage crosstalk of a color filmijNot equal to 0(i not equal to j). Thus, when the illumination light remains constant or when both RGB illumination light components are present, the light of color i has an overall brightness Yi＝∑j＝R，G，BLiτijsjThe matrix form can be expressed as:
full white picture time sj1(j ═ R, G, B), the total luminance obtained was Ytotal＝∑iYi＝∑i，j＝R，G，BLiτij＝∑i＝R，G，BLiτii+∑i，j＝R，G，B，i≠jLiτijThus, it can be seen that when τ isijWhen the color film of one color can penetrate through the LED light of another color, the overall brightness can be improved. But this leads to a reduction in the color gamut for a single color display: suppose that a color film corresponding to a certain i color only allows the LED light of the corresponding color to transmit Yi＝LiτiiDisplaying a monochromatic field s of such colori＝1，sjThe chromaticity coordinates of the chromaticity point at 0(j ≠ i) theoretically coincide with those of the chromaticity point when the LED is lit alone, and are denoted as (x)i，yi). However, in practical cases, the color film corresponding to the i color also allows other colors j to transmit, and the brightness of the generated light is Yj＝Ljτji(j ≠ i). The color coordinates at this time become:
when the visible color mixing results in a monochrome display,. tauijWhen the chromaticity point is 0(i ≠ j), the chromaticity coordinate of the chromaticity point in the monochromatic field is degenerated to the chromaticity point chromaticity coordinate when the LED is turned on alone, that is, the chromaticity point is turned on
In principle, the light flux of the other two lights which can crosstalk and leak light at the input end is reduced for the color with large duty ratio of the pixel, so that the emergent light color accuracy of the sub-pixel with large duty ratio can be directly improved. The essence of the dynamic color gamut scheme provided by the invention is that the driving of each color solid state light emitting element of the illumination light source is dynamically adjusted according to different color components in the display content, so that the displayed color gamut is not degraded to the extent that all RGB each color solid state light emitting elements are in the rated power working state.
In one embodiment of the present invention, for any image signal, there is at least one of the red solid state light emitting element, the green solid state light emitting element, and the blue solid state light emitting element, which is independently adjustable, having the same output power as it is at the time of the full white field image signal. In this type of embodiment, in particular for any image, there is an operating state in which the light source is at nominal power. The technical scheme can reduce the complexity of driving modulation.
In one specific embodiment, the color signal processing module determines the solid-state light-emitting element having the same output power as that in the full-white-field image signal from the sub-pixel having the largest gray-scale value in the original image signal. The sub-pixels described herein correspond to monochrome pixels included in one color pixel, and consideration of the gray-scale values is not taken into consideration for the color pixels but for the sub-pixels. The signal processing method is relatively simple, and the condition that the gray-scale value exceeds the range when the luminous flux output by the light source is reduced is not worried about.
In the invention, for the same frame image, the gray-scale value of any pixel in the optimized image signal is not less than the gray-scale value of the pixel in the original image signal. In the optimized illumination light, the luminous flux of at least one color light is lower than that of the illumination light in the full-white-field image signal, so that the light leakage crosstalk of the color light in the filtering area of the non-corresponding sub-pixel is reduced.
In the present invention, when the luminous flux of one color light (for example, red light) of the optimized illumination light is lower than that of the illumination light in the full white field image signal, that is, the red solid state light emitting device is dimmed, the gray scale value of all the red sub-pixels in the optimized image signal needs to be increased. The optimization criterion is such that, for any pixel, the luminous flux of light from the red solid state light emitting elements exiting from the red pixel filter region in the optimized color image light is equal to the luminous flux of light from the red solid state light emitting elements exiting from the red pixel filter region in the original color image light. That is, the crosstalk component of light leakage from the blue pixel filter region and the green pixel filter region of the red light is not considered, and only the red light emitted from the red pixel filter region is considered to be kept unchanged. It is understood that the above rules can be referred to for blue light and green light, and are not described herein.
It is understood that, in other embodiments of the present invention, the technical solution of the dynamic color gamut may be combined with a technical solution of Global Dimming (Global Dimming), that is, for some image data with a lower overall gray-scale value, the output powers of the three light emitting elements of red, green and blue may be simultaneously reduced, and the gray-scale value of the image data may be simultaneously increased, but the reduction of the output powers of the three light emitting elements of red, green and blue may be set differently according to the red, green and blue components of the image.
In one embodiment of the present invention, when the original image signal is a primary color pure color image signal, such as a full red image, a full green image, or a full blue image, only the solid state light emitting elements of the illumination light source corresponding to the primary color are turned on. The technical scheme ensures that the projection device has good color expression when displaying a monochromatic image, achieves the extreme color of the illumination light source, and is particularly suitable for the scene of PPT demonstration.
In one embodiment of the present invention, when a sub-pixel having the largest gray-scale value in an original image signal belongs to a white pixel, the liquid crystal modulator emits the original color image light without performing image data optimization and illumination light source optimization driving. For a white pixel, the ratio of the gray-scale values of red, green and blue is 1:1:1, and changing the luminous flux of each color solid-state light-emitting element changes the color coordinate of the white pixel, resulting in complication of adjustment. Therefore, the technical scheme of the invention is more suitable for graphic display with brightness mainly concentrated on bright-colored pixels.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A single-plate liquid crystal projector comprises an illumination light source and a liquid crystal modulator, wherein the liquid crystal modulator comprises a liquid crystal modulation layer and a color film, and illumination light emitted by the illumination light source is modulated by the liquid crystal modulation layer and filtered by the color film to form color image light emission
The color signal processing module is used for respectively outputting an illumination light source control signal and an optimized image signal to the illumination light source driving module and the liquid crystal modulator according to at least part of original image signals;
the illumination light source driving module is used for independently controlling the luminous fluxes of at least two color lights contained in the illumination light according to the illumination light source control signal so as to enable the illumination light source to emit optimized illumination light;
the optimized illuminating light is modulated by the liquid crystal modulation layer according to the optimized image signal and filtered by the color film to form optimized color image light for emission; the color image light formed by the modulation of the liquid crystal modulation layer according to the original image signal and the filtering of the color film by the illumination light when the full white field image signal is defined is an original color image light, and the original color image light when the crosstalk leakage of the color film is not considered is defined as an ideal color image light; the color gamut of the optimized color image light is larger than the original color image light, and the illuminance of the optimized color image light is larger than the ideal color image light.
2. The single-panel lcd projection device of claim 1, wherein the illumination source comprises at least a red solid-state light emitting device, a green solid-state light emitting device, and a blue solid-state light emitting device, which are independently controllable, the color film comprises at least a red pixel filter area, a green pixel filter area, and a blue pixel filter area, and any pixel comprises at least three sub-pixels respectively corresponding to the red pixel filter area, the green pixel filter area, and the blue pixel filter area;
the red pixel filter region transmits at least part of light emitted by the green solid-state light-emitting element and/or the blue solid-state light-emitting element, the green pixel filter region transmits at least part of light emitted by the red solid-state light-emitting element and/or the blue solid-state light-emitting element, and the blue pixel filter region transmits at least part of light emitted by the green solid-state light-emitting element and/or the red solid-state light-emitting element.
3. The single panel liquid crystal projection arrangement of claim 2 wherein the illumination source driver module simultaneously drives the red, green, and blue solid state light emitting elements in accordance with the illumination source control signal.
4. The single panel liquid crystal projection arrangement of claim 2, wherein for any image signal, there is at least one of the red, green and blue solid state light emitting elements having the same output power as it would have been at full white image signal.
5. The single-panel liquid crystal projection apparatus of claim 4, wherein the color signal processing module determines the solid state light emitting device having the same output power as that of the full white field image signal according to the sub-pixel having the largest gray scale value in the original image signal.
6. A single plate liquid crystal projection device as claimed in any of claims 2-4 wherein the gray scale value of any pixel in said optimized image signal is not less than the gray scale value of that pixel in said original image signal for the same frame of image.
7. The single-plate liquid crystal projection device according to any of claims 2-4, wherein the optimized illumination light has a luminous flux of at least one color light lower than that of the illumination light at the time of full white image signal.
8. The single plate liquid crystal projection device of any of claims 2-4, wherein the light from the red solid state light emitting elements exiting the red pixel filter in the optimized color image light and the light from the red solid state light emitting elements exiting the red pixel filter in the original color image light have the same luminous flux for any pixel.
9. The single panel liquid crystal projection device of any of claims 2-4, wherein when the original image signal is a primary color solid image signal, only the solid state light emitting elements of the illumination source corresponding to the primary color are turned on.
10. The single plate liquid crystal projection device of any of claims 1-4, wherein the liquid crystal modulator emits the original color image light when the sub-pixel with the largest gray scale value in the original image signal belongs to a white pixel.
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