TWI524816B - Color sequential display and light source control method thereof - Google Patents

Description

Color sequential display and light source control method thereof

The present invention relates to a display device, and more particularly to a color sequential display and a light source control method thereof.

Compared to the spatial domain for color mixing, the color sequential display mixes the three primary colors (red, green, and blue) in the time domain. For example, color sequential projectors, color sequential liquid crystal displays, and the like are all color sequential displays. The projection device can project images onto a larger screen to allow more people to simultaneously view the content displayed on the screen. Therefore, it is often used in public places such as companies and schools. Furthermore, as household display products are moving toward larger sizes, projection devices are becoming more and more popular in general households, and become an everyday electronic product in modern life.

With the advancement of technology, all kinds of electronic products are moving toward high speed, high efficiency, light and thin. Under this trend, pico projectors (or mini projectors) have gradually become the mainstream of the personal digital market in the future. In general, the light source of a pico projector uses a light emitting diode or other solid state light source to increase the lumen required by the pico projector, thereby increasing the brightness of the image projected by the pico projector. After the pico projector is finished, the size of the micro projector's battery is about the same as that of a general mobile phone on the market. Even the pico projector can be integrated into a mobile phone. Therefore, the pico projector has the advantage of being portable and without field restrictions.

However, when the conventional technology displays color images in color sequential, the light source of the pico projector provides light sources corresponding to the three primary colors (ie, red, blue, and green) during the three color sub-pictures, that is, in the same color. Light sources with only one color will illuminate, while other color sources will be turned off. For example, during the red sprite, only the red light source will turn on and illuminate, and the blue light source and the green light source are turned off during the red sprite. In the case where the entire picture is a single solid color, the intensity of the light source is weakened by the time division, so that the use of the pico projector may be limited by the intensity of the ambient light.

FIG. 1A is a schematic diagram of driving waveforms of a conventional color sequential display. Referring to Figure 1A, a conventional color sequential display will during the red sub-picture P _F P _R, P _G sprite during green and blue sub-picture period P _B are provided red light, green light and blue light during screen. Moreover, in the red sub-picture period P _R , the green sub-picture period P _G and the blue sub-picture period P _B , the liquid crystal will display light or opacity corresponding to the display data, so that the red light, the green light and the blue light can Displays the grayscale of the image.

Taking the whole picture as a red picture as an example, FIG. 1B is a schematic diagram of driving waveforms of a red color picture displayed by a conventional color sequential display. Referring to FIG. 1B, the display screen is red, the liquid crystal exhibit a light-transmitting only the P _R during the red sub-picture, the red light to display grayscale images. During the green sub-picture period P _G and the blue sub-picture period P _{B , the} liquid crystal is turned into an opaque state to shield the color light emitted by the green light source and the blue light source, respectively. At this time, in the entire picture period P _F , the displayed red picture only uses the red sub-picture period P _{R to} display red light, that is, the actual display time of the red picture will be equal to (or even less than) the three-thirds of the picture period P _F . First, the brightness of the red picture is greatly reduced, which affects the visibility of the red picture.

The invention provides a color sequential display and a light source control method thereof, which can increase the illumination time of the color light source to increase the brightness of the color sequential display when displaying a single color picture.

The invention provides a light source control method for a color sequential display, which comprises the following steps. The screen material during the screen is received, wherein the screen period includes a plurality of dice picture periods. Data analysis is performed based on the screen data to obtain a gray scale distribution of a plurality of colors in the screen material. Based on the gray scale distribution of these colors, it is determined whether to turn on part or all of the plurality of color light sources of the color sequential display during the picture period. Wherein, the illumination time of the above-mentioned turned-on color light source is greater than any of these color sub-picture periods.

The invention also provides a color sequential display comprising a display panel, a light source module and a control module. The light source module provides a plurality of color light sources to the display panel. The control module receives the screen data during the screen and performs data analysis according to the screen data to obtain the gray scale distribution of the plurality of colors in the screen data. The control module determines whether to turn on some or all of the color light sources during the picture period according to the gray scale distribution of the colors. Wherein, the picture period includes a plurality of dice picture periods, and the on-time color source has a longer illumination time than any of the dice picture periods.

Based on the above, the color sequential display and the light source control method thereof according to the embodiment of the present invention, according to the gray scale distribution of the three primary colors, turn off the color light source with less or no use when the obtained picture material is a solid color picture, and turn on the corresponding solid color. The color source of the picture. Wherein, the illumination time of the turned-on color light source is greater than the period of one of the color sub-pictures. Thereby, the illumination time of the color light source can be increased to increase the maximum brightness of the light source module. In some embodiments, liquid crystal light leakage is avoided by turning off the unused color light source, thereby improving the color purity of the picture.

The above described features and advantages of the present invention will be more apparent from the following description.

2A is a schematic diagram of a system of a color sequential display according to an embodiment of the invention. Referring to FIG. 2A, the color sequential display (for example, the projector 200) includes a control module 210, a light source module 220, and a liquid crystal panel 230. The liquid crystal panel 230 may be a liquid crystal on silicon (hereinafter referred to as LCOS) panel. And the projector 200 can be a pico projector. The control module 210 receives the video signal VS, generates the display data DS to the liquid crystal panel 230 according to the picture data transmitted by the video signal VS, and generates the driving signal SDR to the light source module 220. The liquid crystal panel 230 displays the sub-screens corresponding to different colors according to the display data DS, and the light source module 220 synchronously supplies the corresponding color light to the liquid crystal panel 230 according to the driving signal SDR. The liquid crystal panel 230 projects light to a target (such as a curtain or a wall) by the light source provided by the reflective/transmissive light source module 220 to display an image.

In the present embodiment, the liquid crystal panel 230 is exemplified by a color sequential LCOS (Color Sequential LCOS, CS-LCOS). Therefore, a color filter is not formed on the liquid crystal panel 230. Moreover, the projector 200 realizes temporal mixing by using the Color Sequential (CS) method to display a color image. At this time, the light source module 220 can correspondingly provide light sources of different colors (such as red light, blue light, and green light) at a plurality of different times in the picture period P _F . Among them, the red light, the blue light, and the green light can be provided by using the corresponding color light emitting diode light, that is, the red light emitting diode, the blue light emitting diode, and the green light emitting diode are used as the red light source, blue. Light source and green light source.

2B is a system diagram of the control module 210 of FIG. 2A. Referring to FIG. 2A and FIG. 2B , the control module 210 includes a signal processing unit 211 , a data analysis unit 213 , and a light source control unit 215 . The signal processing unit 211 receives the picture data transmitted by the video signal VS, and generates the display data DS according to the video signal VS. The signal processing unit 211 can generate the display data DS by using an image simulation technique such as a frame rate control method or a pixel dithering method. The data analysis unit 213 receives the picture data and the display data DS transmitted by the video signal VS, and analyzes the picture to be displayed based on the picture data and the display data DS, thereby generating an analysis result RA.

The light source control unit 215 generates a driving signal SDR according to the analysis result RA, and the light source control unit 215 provides a corresponding number of driving signals SDR according to the number of color light sources provided by the light source module 220. In other words, it is assumed here that the light source module 220 can provide red light, blue light, and green light. Therefore, the light source control unit 215 correspondingly generates three driving signals SDR to respectively control the red light emitting diode and the blue light emitting diode. And green LEDs emit light.

Further, when the data analysis unit 213 receives the screen data and the display data DS during one screen, the data analysis unit 213 performs analysis to obtain the gray scale distribution of the three primary colors (ie, red, blue, and green) as the analysis result RA. In the case where the entire picture is a single color, when the gray level average of the gray scale distribution of one of the three primary colors is less than or equal to a critical value, it means that the picture has almost no such color component, so the light source control unit 215 can turn off the color light source of the color when the screen is displayed (in the period of the associated picture); otherwise, when the gray level average of the gray scale distribution of the color is greater than the critical value, the light source control unit 215 opens the corresponding Color color light source.

For example, when the gray level average of the gray scale distribution of the red color in the three primary colors is less than or equal to a critical value, it means that the picture has almost no red component, so the light source control unit 215 can turn off the red light source during the picture period P _F ; When the grayscale average of the gray scale distribution of the red is greater than the threshold, the light source control unit 215 correspondingly turns on the red light source. The threshold value is generally a lower gray scale value (for example, a gray scale value of 15). However, the threshold value may be different according to actual circuit design and no use habit, and is not limited thereto.

In addition, in addition to determining whether to turn off the corresponding color light source according to the grayscale average value of each color, the light source control unit 215 may determine whether to close the corresponding color light source according to whether the grayscale range of each color is located in the critical range. . In other words, when the gray scale distribution range of a certain color is located in the critical range, the light source control unit 215 turns off the color light source corresponding to the color; otherwise, when the gray scale distribution range of the color exceeds the critical range, the light source The control unit 215 turns on a color light source corresponding to this color.

3A-3H are schematic diagrams showing driving waveforms of different solid color pictures according to an embodiment of the invention. Referring to FIG. 2B and FIG. 3A, it is assumed here that the picture period P _{F is} divided into a red sub-picture period P _R , a green sub-picture period P _{G ,} and a blue sub-picture period P _B . The signal processing unit 211 generates a display data DS including red sub-picture data, green sub-picture data and blue sub-picture data according to the video signal VS to the display panel 230, wherein the display panel 230 will be in the red sub-picture period P _R , green sub- The picture period P _G and the blue sub-picture period P _B respectively display corresponding red sub-picture data, green sub-picture data, and blue sub-picture data. If the video signal VS displays the picture data having the full red picture in the picture period P _F , the data analysis unit 213 transmits the gray scale distribution of the three primary colors to the light source after analyzing the video signal VS and/or the display data DS. Control unit 215.

In the red picture, the blue and green dorms are less or not mixed, so that the blue and green grayscale averages will be less than or equal to the critical value, or the blue and green grayscale distributions will be located. Within the critical range. In other words, the grayscale average of red will be greater than the critical value, or the grayscale distribution of red will exceed the critical range. Therefore, the light source control unit 215 turns off the blue light source corresponding to the blue sub-picture period P _{B and} the green light source corresponding to the green sub-picture period P _G , and only turns on the red light source corresponding to the red sub-picture period P _R .

In addition, the red light source will have a longer illumination time than the corresponding sub-picture period P _R . In the present embodiment, the illumination time of the red light source is the entire picture period P _F . At this time, the liquid crystal is correspondingly kept in a light transmitting state, so that the red light can display the gray scale of the image. Since the red light is continuously provided during the picture period P _F , the usage rate of the red light source can be increased, thereby increasing the maximum brightness when the liquid crystal panel 230 displays the full red picture.

Similarly, if the video signal VS displays the picture material having the full green picture in the picture period P _F , the light source control unit 215 controls the green light source of the light source module 220 to continuously provide green light during the picture period P _F , and the red light source The blue light source will be turned off, and its driving waveform is as shown in Fig. 3B. If the video signal VS displays the picture material having the full blue picture in the picture period P _F , the light source control unit 215 controls the green light source of the light source module 220 to continuously provide blue light during the picture period P _F , and the red light source and the green light source It will be turned off and its driving waveform is shown in Figure 3C.

On the other hand, the light-emitting time of the red light source, the green light source, and the blue light source is not limited to be equal to the picture period P _F but may be smaller than the picture period P _F but still larger than the corresponding color sub-picture period. For other solid color images (such as yellow, cyan, magenta, etc.), the light source control unit 215 can control the light source module 220 to simultaneously turn on the plurality of color light sources in the red light source, the green light source, and the blue light source. . The illumination time of the red light source, the green light source and the blue light source may also be equal to the picture period P _F or less than the picture period P _F , but still greater than the red sub-picture period P _R , the green sub-picture period P _G and the blue sub-picture period One of P _B.

Referring to Figure 3D, when the video signal VS is shown with a yellow full screen (i.e. blending red and green) P _F during the picture screen information, the light source control unit 215 controls the light source module 220 is closed during the blue in the picture P _F The color light source, and the red light source and the green light source are turned on to emit light. The red light source and the green light source emit light simultaneously during the red sub-picture period P _R and the green sub-picture period P _G , that is, the red light source and the green light source have the same illumination time, and the red light source and the green light source have the same illumination time. The sum of the red sub-picture period P _R and the green sub-picture period P _G . Since the blue light source is turned off, the display panel 230 does not leak blue light during the blue sub-picture period P _B . Therefore, the present embodiment can improve the problem of color purity and improve the overall brightness of the yellow screen.

Similarly, referring to FIG. 3E, if the video signal VS displays the picture material having the full cyan picture (ie, the mixed color of green and blue) in the picture period P _F , the light source control unit 215 controls the light source module 220 during the picture. The red light source is turned off in P _F , and the green light source and the blue light source are turned on to emit light. Further, the green light source and the blue light source emit light simultaneously in the green sub-picture period P _G and the blue sub-picture period P _B .

Referring to 3F, a display when the video signal VS having a full screen magenta (i.e., red and blue color mixing) P _F during the picture screen information, the light source control unit 215 controls the light source module 220 is closed during the picture P _F The green light source, while the red light source and the blue light source are turned on to emit light. Further, the red light source and the blue light source emit light simultaneously in the red sub-picture period P _R and the blue sub-picture period P _B . In some embodiments, in addition to the red sub-picture period P _R and the blue sub-picture period P _B , the red light source and the blue light source are further illuminated during the green sub-picture P _G , and the liquid crystal panel 230 is correspondingly in the green sub- P _G is in a light transmitting state during the picture.

Similarly, referring to FIG. 3G, if the video signal VS displays the picture material having the full white picture (ie, the mixed color of red, green, and blue) in the picture period P _F , the light source control unit 215 controls the light source module 220 to During the picture period P _F , the red light source, the green light source, and the blue light source are turned on while emitting light. Referring to FIG. 3H, if the video signal VS displays the picture material having the full black picture in the picture period P _F , the light source control unit 215 controls the light source module 220 to turn off the red light source, the green light source and the blue light source during the picture period P _F . , so that the red light, green light and blue light source will not emit light during P _F screen.

According to the above, if the data analysis unit 213 receives a solid color picture (for example, pure red, pure green, pure blue, pure yellow, pure magenta, pure blue or pure black) or a picture close to a solid color, the data analysis unit 213 transmits the light source. The control unit 215 turns on some or all of the red light source, the green light source, and the blue light source, and turns off the remaining color light sources. Moreover, in the sub-picture period corresponding to the turned-on color light source or during the picture period P _F , the turned-on color light source continues to emit light. Since the illumination time of each color light source is increased, the maximum brightness of the solid color picture can be increased, and the unused color light source can be turned off to reduce the power consumption of the light source module 220.

According to the above, the light source control method of the one-color sequence display can be integrated. 4 is a flow chart of a light source control method for a color sequential display according to an embodiment of the invention. Referring to FIG. 4, first, a picture material is received during a picture period (step S410), wherein the picture period includes a plurality of color sub-picture periods (eg, a red sub-picture period P _R , a green sub-picture period P _{G ,} and a blue sub-picture). During the picture period P _B ). Then, data analysis is performed based on the screen data to obtain a grayscale distribution of the three primary colors in the screen material (step S420). Then, according to the gray scale distribution of the three primary colors, determining whether to turn on part or all of the plurality of color light sources provided by the light source module of the color sequential display during the screen period (step S430), wherein the light source of the open color light source is illuminated The time is greater than any of these dice picture periods. The details of each step can be referred to the above description, and will not be described here.

In summary, the color sequential display and the light source control method thereof according to the embodiments of the present invention, according to the gray scale distribution of the three primary colors, turn off the color light source with less or no use when the obtained picture data is a solid color picture, and turn on A color light source corresponding to a solid color picture. The turned-on color light source continues to emit light during a plurality of dice picture periods or during the entire picture period. Embodiments of the present invention can increase the maximum brightness of a solid color picture by increasing the illumination time of the color source during the picture period P _F . By turning off the unused color light source, the embodiment of the present invention can improve the light leakage problem and improve the color purity of the picture. Furthermore, the embodiment of the present invention can reduce the power consumption of the light source module by turning off the color light source that is not used.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

200. . . Projector

210. . . Control module

211. . . Signal processing unit

213. . . Data analysis unit

215. . . Light source control unit

220. . . Light source module

230. . . LCD panel

VS. . . Video signal

SDR. . . Drive signal

RA. . . Analysis result

DS. . . Display data

P _F . . . During the picture

P _R , P _G , P _B . . . Period of dice

S410, S420, S430. . . step

FIG. 1A is a schematic diagram of driving waveforms of a conventional color sequential display.

FIG. 1B is a schematic diagram showing driving waveforms of a red color picture displayed by a conventional color sequential display.

2A is a schematic diagram of a system of a color sequential display according to an embodiment of the invention.

2B is a schematic diagram of the system of the control module of FIG. 2A.

3A-3H are schematic diagrams showing driving waveforms of different solid color pictures according to an embodiment of the invention.

4 is a flow chart of a light source control method in accordance with an embodiment of the present invention.

S410, S420, S430. . . step

Claims (15)

A light source control method for a color sequential display, comprising: receiving a picture data during a picture period, wherein the picture period includes a plurality of color sub picture periods; performing data analysis according to the picture data to obtain a plurality of the picture data a grayscale distribution of colors; and determining whether to turn on part or all of the plurality of color light sources of the color sequential display during the picture period, wherein the light time of the color light source that is turned on is greater than Any of the periods of the dice pictures, and the un-opened color source does not emit light during the picture period. The light source control method of the color sequential display according to claim 1, wherein “determining whether to turn on the plurality of color light sources of the color sequential display during the screen period according to the gray scale distribution of the colors Or all of the steps include: when a grayscale average of a first color of the colors is greater than a threshold, turning on a first color source corresponding to the first color of the color sources; and when the gray When the step average is less than or equal to the threshold, the first color source is turned off. The light source control method of the color sequential display according to claim 1, wherein “determining whether to turn on the plurality of color light sources of the color sequential display during the screen period according to the gray scale distribution of the colors Or all" steps include: When a gray scale distribution range of a first color of the colors exceeds a critical range, turning on a first color light source corresponding to the first color of the color light sources; and when the gray scale distribution range of the first color When falling within the critical range, the first color light source is turned off. The light source control method of the color sequential display according to claim 1, wherein when the plurality of color light sources are turned on, the light emitting times of the turned-on color light sources are the same as each other. The light source control method of the color sequential display according to claim 1, wherein when the color light source is turned on, the light emitting time of the turned-on color light sources is equal to part or all of the color image periods. The sum of them. The light source control method of the color sequential display according to claim 1, wherein the illumination time of the turned on color light source is equal to the picture period. The light source control method of the color sequential display according to claim 1, wherein the turned on color light source emits light at the same time. A color sequential display comprising: a display panel; a light source module providing a plurality of color light sources to the display panel; and a control module for receiving a picture data during a picture, the control module according to the picture data Performing data analysis to obtain gray scale distributions of the plurality of colors in the picture material, and the control module determines whether to turn on the color light sources during the picture period according to the gray scale distribution of the colors Part or all, wherein the picture period includes a plurality of dice picture periods, and the on-time color source has a illumination time greater than any of the dice picture periods, and the un-on color source is not in the picture period Glowing. The color-sequential display of claim 8, wherein the control module comprises: a signal processing unit that receives the picture data to generate a plurality of display materials according to the picture data to the display panel; Receiving, by the unit, the picture data and the display materials, and performing data analysis on the picture data and the display materials to obtain gray scale distribution of the colors as an analysis result; and a light source control unit receiving the analysis result To determine whether to turn on some or all of the color light sources. The color sequential display of claim 8, wherein the control module turns on the color light sources of the light source module when a grayscale average value of a first color of the colors is greater than a threshold value a first color light source corresponding to the first color, and the control module turns off the first color light source of the light source module when the gray level average value is less than or equal to the critical value. The color sequential display of claim 8, wherein the control module turns on the color light sources of the light source module when a gray scale distribution range of a first color of the colors exceeds a critical range; Corresponding to a first color light source of the first color, and the control module turns off the light source mode when the gray scale distribution range of the first color is located in the critical range The first color source of the group. The color sequential display of claim 8, wherein when the plurality of color light sources are turned on, the light emitting times of the turned-on color light sources are the same as each other. The color sequential display of claim 8, wherein when the plurality of color light sources are turned on, the light emitting time of the turned-on color light sources is equal to a sum of part or all of the color image periods. The color sequential display of claim 8, wherein the illumination time of the open color light source is equal to the picture period. The color sequential display of claim 8, wherein the open color light source emits light at the same time.