JP6299108B2 - Electro-optical device drive device, electro-optical device drive method, electro-optical device, and electronic apparatus - Google Patents

Description

  The present invention relates to field sequential driving.

  When an image is formed by field sequential drive, typically, a frame for displaying an image of one frame is set to one of three primary colors of red (R), green (G), and blue (B). The image is divided into a plurality of corresponding fields, and an image signal of a color component corresponding to each field is written to the pixel, and the color of light irradiated to the pixel is switched in synchronization with the writing of the image signal (for example, Patent Documents 1 and 2). reference). Japanese Patent Application Laid-Open No. H10-228561 discloses that light sources of a plurality of colors are turned on when monochrome gradation is expressed by field sequential driving.

JP 2005-17492 A Japanese Patent Application Laid-Open No. 2011-232743

In field sequential drive image formation, the occurrence of color breakup (also referred to as color breakup) may be a problem. Color breakup occurs when light of each of the three primary colors is imaged at different positions on the retina of the human eye when a human eye follows the object moving on the screen. For example, as shown in FIG. 13, when a white object (window) moves from N frames to N + 1 frames with black as a background, each color of RGB is visually recognized by the observer at the boundary between the object and the background. There is. Color breakup becomes less noticeable by generating images of each field using light other than the three primary colors, but instead, the color change in the image of the field is perceived by the observer as a reduction in image quality. there is a possibility.
The present invention has been made in view of the above-described circumstances, and one of its purposes is to make color breakup inconspicuous while making it difficult for an observer to perceive a decrease in image quality.

An electro-optical device drive device according to the present invention includes an optical modulator including a light source that independently emits light of each of a plurality of colors and a pixel that modulates light emitted from the light source based on an image signal. A driving device for an optical device, wherein a unit frame for driving the pixels is divided into a plurality of fields, and image signals of the plurality of colors are assigned to a first field and the first field corresponding to the same color. In the case of forming a first image including a color image in the unit frame and a driving unit that sequentially arranges the second field in a predetermined color order and sequentially writes the pixel, the image signal of the second field In the case where the light of each color of the plurality of colors is emitted to the light source in the color order to form a second image including a black and white image in the unit frame in synchronization with the writing of the image of the second field, Write signal In synchronism with, the respective colors of light of the plurality of colors, at least 2 times faster than the case of forming the first image, and a light source control unit to emit the light.
According to the present invention, when a second image including a black and white image is formed with respect to the second field in which the light synchronized with the writing of the image signal is emitted to the light source, the first field has other colors. By emitting light to the light source, it is possible to make the color breakup inconspicuous while making it difficult for the observer to perceive the deterioration in image quality.

In the electro-optical device drive device according to the aspect of the invention, the light source control unit may detect the first field with respect to the light emission time of each color in the second field according to a region where the black and white image is formed. You may change the ratio of the said injection time.
According to the present invention, light of each color can be emitted to the light source in an emission time that takes into account the conspicuous color breakup according to the area of the black and white image.

In the electro-optical device drive device, the light source control unit may increase the ratio as the area is larger.
According to the present invention, it is difficult for an observer to perceive a deterioration in image quality by emitting light of each color to a light source in an emission time that takes into account the conspicuousness of color breakup according to the area of a black and white image. Can do.

In the electro-optical device driving device according to the present invention, the electro-optical device driving device includes an analysis unit that analyzes input image data in which the gradation values of the plurality of colors are designated for each pixel and obtains a histogram of gradation differences of the plurality of colors. The light source control unit may determine a region where the black and white image is formed based on the histogram obtained by the analysis unit.
According to the present invention, a monochrome image region can be easily determined based on a histogram of gradation differences of a plurality of colors for each pixel.

In the driving device for the electro-optical device according to the aspect of the invention, the light source emits light of three colors of a first color, a second color, and a third color, and the driving unit includes the first color, In the order of the second color and the third color, the image signal is written to the pixel in succession by two fields, and the light source control unit forms the first color when forming the first image. In the order of the second color and the third color, when the light source emits the light of each color to form the second image, the second color, the third color, and the The light of each color may be emitted to the light source in the order of the first color at twice the speed when forming the first image.
According to the present invention, when forming an image using three colors of light of the first, second and third colors, when forming a second image including a monochrome image, the first image including a color image is included. Compared to the case of forming an image, the color order of light emitted to the light source may be changed, and light of each color may be emitted to the light source at double speed.

In the drive device of the electro-optical device according to the aspect of the invention, when the number of colors of the image signal written by the drive unit is larger than the number of colors of the light emitted from the light source, the light source control unit Regardless of whether or not the image signal is written in the second field, the light of each color of the plurality of colors is emitted at the double speed or more when forming the first image. May be injected.
According to the present invention, color breakup can be made inconspicuous even when an image having a color larger than the number of colors emitted from the light source is generated.

  The present invention can be conceived as a driving method of an electro-optical device, an electro-optical device, and an electronic apparatus in addition to the driving device of the electro-optical device.

FIG. 2 is a plan view showing the configuration of the projector according to the first embodiment. FIG. 2 is a block diagram showing an electrical configuration of the projector according to the embodiment. FIG. 3 is a diagram illustrating a configuration of a panel driving unit and an electro-optical panel according to the embodiment. FIG. 3 is a diagram showing an equivalent circuit in the electro-optical panel according to the embodiment. 6 is a timing chart showing the operation of the projector according to the embodiment. 6 is a timing chart showing changes in display of field images in the embodiment. 6 is a flowchart showing a flow of processing for selecting an injection pattern in the embodiment. The figure which shows an example of the histogram which the analysis part which concerns on the same embodiment calculated | required. 6 is a timing chart showing the operation of a projector according to a modification of the embodiment. 6 is a timing chart for explaining the operation of the projector according to the modification. 9 is a timing chart showing the operation of a projector according to a second embodiment. 6 is a flowchart showing a procedure for selecting an injection pattern in the embodiment. Explanatory drawing of the principle that a color breakup occurs.

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, an example in which the electro-optical device of the invention is applied to a projector will be described.
[First Embodiment]
FIG. 1 is a plan view showing the configuration of the projector according to the first embodiment of the invention. The projector 1 is a single-plate liquid crystal projector (an example of an electronic device), forms an image on the electro-optical panel 100 by field sequential driving, and projects image light on a reflective screen S.
As shown in FIG. 1, the projector 1 includes a red (R) color that is a first color, a green (G) color that is a second color, and a blue (B) color that is a third color. Light sources 11R, 11G, and 11B are provided as light sources corresponding to the primary colors. The light source 11R is a light emitting diode (LED) that emits R-color laser light. The light source 11G is a light emitting diode that emits G-color laser light. The light source 11B is a light emitting diode that emits B-color laser light. The laser beams emitted from the light sources 11R, 11G, and 11B are incident on the cross prism 13 with the emission angles adjusted by the angle adjusting optical elements 12R, 12G, and 12B, respectively. In the cross prism 13, the R and B laser beams are refracted by 90 degrees, while the G laser beam goes straight. The cross prism 13 emits laser light incident from each of the light sources 11R, 11G, and 11B to the fly-eye lens 14.

  The fly-eye lens 14 is an optical member (integrator) in which a plurality of lenses are two-dimensionally arranged on a substrate. The fly-eye lens 14 spatially divides and emits an incident light beam of laser light incident from the cross prism 13. A PBS (Polarization Beam Splitter) 15 is a polarization beam splitter that selectively transmits a specific polarization (for example, s-polarized light) of laser light incident from the fly-eye lens 14 and selects the other polarization (for example, p-polarized light). It is an optical member that reflects light. The laser light transmitted through the PBS 15 is incident on the electro-optical panel 100 through the telecentric optical system 16 including a lens and a diaphragm.

  Here, the electro-optical panel 100 is a transmissive liquid crystal light valve, and is an optical modulator including pixels that modulate laser light incident from the telecentric optical system 16 based on an image signal. The electro-optical panel 100 emits laser light modulated by the pixels to the projection unit 17 as image light. The projection unit 17 enlarges and projects the image light emitted from the electro-optical panel 100 onto the screen S.

FIG. 2 is a block diagram showing an electrical configuration of the projector 1.
The controller 20 of the projector 1 includes a logical operation circuit such as a CPU (Central Processing Unit), and controls each unit of the projector 1. The controller 20 includes various control signals for the horizontal synchronization signal HS, the vertical synchronization signal VS, and the dot clock CLK, and input image data R-DATA, G-DATA, and B-DATA corresponding to R, G, and B colors. Are input in parallel. Each control signal and input image data input to the controller 20 are generated by, for example, a video signal source (for example, a video playback device such as a DVD playback device or a personal computer) outside the projector 1 and input to the controller 20. .

  Input image data R-DATA, G-DATA, and B-DATA are image data for forming an image of one frame as a unit frame on the electro-optical panel 100. The input image data R-DATA, G-DATA, and B-DATA have a period of 16.7 milliseconds (that is, the frame frequency is 60 Hz) and one frame (that is, all pixels of the electro-optical panel 100) is input. The Here, the frame refers to a period required to form an image for one frame by driving the pixels of the electro-optical panel 100.

  As will be described in detail later, the projector 1 divides one frame into a plurality of fields (time division), and images of any one of R, G, and B colors (hereinafter referred to as “field images”) for each field. ) Is generated and displayed to perform field sequential drive image formation. The input image data R-DATA is input image data for generating a field image corresponding to R color (hereinafter referred to as “R field image”), and is data in which an R color gradation value is designated for each pixel. is there. The input image data G-DATA is input image data for generating a field image corresponding to G color (hereinafter referred to as “G field image”), and is data in which a G tone value is designated for each pixel. is there. The input image data B-DATA is input image data for generating a field image corresponding to B color (hereinafter referred to as “B field image”), and is data in which a gradation value of B color is designated for each pixel. is there. In the present embodiment, the gradation values of R, G, and B colors are represented by 8-bit data (that is, 256 gradations). That is, the gradation value takes any value from “0” to “255”, and a larger value corresponds to a brighter (that is, higher luminance) gradation, and conversely, the smaller the value, the darker (that is, Corresponds to gradations with low brightness.

The controller 20 includes an image data processing unit 21, a timing control unit 22, an analysis unit 23, and a light source control unit 24.
The image data processing unit 21 stores input image data R-DATA, G-DATA, and B-DATA input in parallel in a frame memory (not shown), performs parallel-serial conversion, and outputs the result to the panel drive unit 30. It is a processing circuit. The image data processing unit 21 generates image data DATAw for displaying the R, G, and B color field images in a time-sharing manner and outputs the generated image data DATAw to the panel drive unit 30.

  The timing control unit 22 is a circuit that generates various timing signals and outputs them to the panel drive unit 30. Specifically, the timing control unit 22 generates a start pulse Dy and a clock signal Cly based on the horizontal synchronization signal HS, the vertical synchronization signal VS, and the dot clock CLK, and outputs them to the scanning line driving circuit 130. In addition, the timing control unit 22 generates a start pulse Dx and a clock signal Clx based on the horizontal synchronization signal HS, the vertical synchronization signal VS, and the dot clock CLK, and outputs them to the data line driving circuit 140.

  The analysis unit 23 analyzes the input image data R-DATA, G-DATA, and B-DATA, calculates a gradation difference ΔV of R color, G color, and B color for each pixel, and a histogram of the gradation difference ΔV. (That is, a frequency distribution). The analysis unit 23 calculates the gradation difference ΔV based on the combination that gives the maximum gradation difference among the gradation values of R, G, and B colors. The histogram of the gradation difference ΔV is used to easily determine an area including a color image and a monochrome image in an image formed on the electro-optical panel 100.

The light source control unit 24 is a circuit that performs control (that is, light source control) to emit light to the light sources 11R, 11G, and 11B. Specifically, the light source control unit 24 independently outputs a light source control signal for instructing turning on or off to each of the R color LED driver 40R, the G color LED driver 40G, and the B color LED driver 40B. The R color LED driver 40R turns on or off the light source 11R according to the supplied light source control signal. The G color LED driver 40G turns on or off the light source 11G according to the supplied light source control signal. The R color LED driver 40B turns on or off the light source 11B according to the supplied light source control signal. The light sources 11R, 11G, and 11B emit laser light during the lighting period.
The light source control unit 24 performs light source control according to the gradation difference ΔV histogram obtained by the analysis unit 23. Details of the light source control will be described later.

FIG. 3 is a diagram illustrating configurations of the panel driving unit 30 and the electro-optical panel 100.
The electro-optical panel 100 has a configuration in which a plurality of pixels 110 are arranged in a matrix. Specifically, in the electro-optical panel 100, m scanning lines 112 extend in the X (horizontal) direction in FIG. 1, while n data lines 114 are electrically insulated from the scanning lines 112, while In FIG. 3, it extends in the Y (vertical) direction (m and n are natural numbers of 2 or more). A pixel 110 is provided corresponding to each intersection of the plurality of scanning lines 112 and the plurality of data lines 114. In the present embodiment, the pixels 110 are arranged in a matrix of m rows × n columns.

FIG. 4 is a diagram illustrating an equivalent circuit in the electro-optical panel 100.
As shown in FIG. 4, the electro-optical panel 100 has a configuration in which liquid crystal elements 120 each having a liquid crystal 105 sandwiched between a pixel electrode 118 and a common electrode 108 are arranged corresponding to the intersection of a scanning line 112 and a data line 114. is there. In the equivalent circuit of the electro-optical panel 100, as shown in FIG. 4, an auxiliary capacitor (storage capacitor) 125 is provided in parallel with the liquid crystal element 120. The auxiliary capacitor 125 has one end connected to the pixel electrode 118 and the other end commonly connected to the capacitor line 115. The capacitor line 115 is maintained at a constant voltage over time.
Here, when the scanning line 112 becomes H level, the TFT 116 having the gate electrode connected to the scanning line is turned on, and the pixel electrode 118 is connected to the data line 114. Therefore, when a data signal having a voltage corresponding to the gradation is supplied to the data line 114 when the scanning line 112 is at the H level, the data signal is applied to the pixel electrode 118 via the turned-on TFT 116. When the scanning line 112 becomes L level, the TFT 116 is turned off, but the voltage applied to the pixel electrode 118 is held by the capacitor of the liquid crystal element 120 and the auxiliary capacitor 125.
In the liquid crystal element 120, the molecular alignment state of the liquid crystal 105 changes according to the electric field generated by the pixel electrode 118 and the common electrode 108. For this reason, if the liquid crystal element 120 is a transmission type, it has a transmittance corresponding to the applied / holding voltage. In the electro-optical panel 100, since the transmittance changes for each liquid crystal element 120, the liquid crystal element 120 corresponds to a pixel.
In this embodiment, the liquid crystal 105 is a VA (Vertical Alignment) type liquid crystal, and a normally black mode in which the liquid crystal element 120 is in a black state when no voltage is applied.

Returning to FIG.
The scanning line driving circuit 130 sequentially shifts the start pulse Dy in accordance with the clock signal Cly, and the scanning signals SC1, SC2, SC3, SC4,. , SCm.
Based on the start pulse Dx and the clock signal Clx, the data line driving circuit 140 applies image signals (data signals) d1, d2, d3, d4 to the data lines 114 in the 1, 2, 3,. d5,..., dn are supplied, and an image signal is written in the pixel 110. Image signals d 1, d 2, d 3, d 4, d 5,..., Dn are voltage signals for expressing gradation in the pixel 110 with designated gradation values. Each of the image signals d1, d2, d3, d4, d5,..., Dn supplied by the data line driving circuit 140 is supplied to the pixel 110 corresponding to the scanning line 112 selected by the scanning line driving circuit 130.
Under the configuration described above, the panel drive unit 30 drives the electro-optical panel 100 line-sequentially and writes image signals corresponding to the R, G, and B colors to the pixels 110 based on the image data DATAw. .
The panel driving unit 30 preferably drives the liquid crystal element 120 with an alternating current in order to prevent a direct current component from being applied to the liquid crystal 105. Since such AC driving is well known, description thereof is omitted in this embodiment.

FIG. 5 is a timing chart showing the operation of the projector 1. FIG. 5 shows an operation related to image formation of one frame.
The controller 20 starts an operation for forming an image of one frame in accordance with the input vertical synchronization signal VS. In addition, the controller 20 outputs a start pulse Dy to the panel drive unit 30 at a timing at which driving of each field constituting one frame is started. The column labeled “DATAw” in FIG. 5 shows temporal changes in the image data DATAw supplied by the controller 20. The column labeled “Field Image” in FIG. 5 shows temporal changes in the field image displayed by the electro-optical panel 100. The controller 20 equally divides one frame into a first half period and a second half period, and further divides each of the first half period and the second half period into six fields. In each of the first half period and the second half period, the controller 20 makes the first and second fields from the top correspond to the R color, the third and fourth fields correspond to the G color, and the fifth and sixth fields. Is made to correspond to the B color. In the following description, these six fields are referred to as “R1 field”, “R2 field”, “G1 field”, “G2 field”, “B1 field”, and “B2 field” in order from the top.

  Further, the controller 20 determines whether an image formed in one frame is a color pattern or a monochrome pattern based on the histogram of the gradation difference ΔV. Processing related to this determination will be described later. When the controller 20 determines that the color pattern is a color pattern (an example of the first image), the light source is controlled according to the emission pattern A. When it is determined that the monochrome pattern is mainly a monochrome image (an example of the second image), light source control according to the emission pattern B is performed. In the emission pattern A and the emission pattern B, the temporal changes in the light emitted from the light sources 11R, 11G, and 11B are different.

Next, the operation of the projector 1 when performing light source control according to the emission pattern A will be described with reference to FIG.
First, when starting the R1 field, the controller 20 controls the panel driving unit 30 so that the image signal dr1 for displaying the R field image is written in the electro-optical panel 100. The panel drive unit 30 writes an image signal to each pixel 110 line-sequentially from the top of the screen of the electro-optical panel 100 in the downward direction (Y direction) according to the control of the controller 20. Therefore, in the R1 field, the image of the previous frame (the previous field) remains on at least a part of the electro-optical panel 100. Therefore, in the R1 field, the controller 20 turns off the light sources 11R, 11G, and 11B over the entire R1 field so that the viewer does not visually recognize the image displayed on the electro-optical panel 100.

  Next, when the controller 20 starts the R2 field, the controller 20 controls the panel drive unit 30 to write the image signal dr2 for expressing the R field image to the electro-optical panel 100. Here, the controller 20 controls the panel drive unit 30 so as to write an image signal for displaying the same R field image as the R1 field. In the R2 field, in order for the viewer to visually recognize the image displayed on the electro-optical panel 100, the controller 20 causes the light source 11R to emit R light and turns off the light sources 11G and 11B over the entire R2 field.

Subsequently, the operation related to the G1 field and the G2 field will be described. However, the operation related to the R color in the R1 field and the R2 field is substantially the same as the operation in which the operation is replaced with the G color.
That is, in order to display the G field image, the controller 20 writes the image signal dg1 to the electro-optical panel 100 in the G1 field, and writes the image signal dg2 to the electro-optical panel 100 in the G2 field. Further, the controller 20 turns off the light sources 11R, 11G, and 11B in the G1 field, causes the light source 11G to emit light of G color over the entire G2 field, and turns off the light sources 11R and 11B.

Next, the operation related to the B1 field and the B2 field will be described. The operation related to the G color in the G1 field and the G2 field is substantially the same as the operation in which the operation is performed with the B color.
That is, in order to display the B field image, the controller 20 writes the image signal db1 to the electro-optical panel 100 in the B1 field, and writes the image signal db2 to the electro-optical panel 100 in the B2 field. In addition, the controller 20 turns off the light sources 11R, 11G, and 11B in the B1 field, causes the light source 11B to emit light of B color over the entire B2 field, and turns off the light sources 11R and 11G.

The above is the description of the operation of the projector 1 in the first half period of one frame. The projector 1 operates in the second half period of one frame as in the first half period.
For this reason, when the emission pattern A is selected, the controller 20 outputs the light of each color of R, G, and B to the light sources 11R, 11G in synchronization with the writing of the image signals of the R2, G2, and B2 fields. , 11B. The term “synchronization” as used herein means that the color component of the image signal written to the pixel 110 is the same as the color of light emitted to the pixel 110. Therefore, when fields are arranged in the order of R, G, and B (color order) in one frame, the controller 20 similarly uses the light sources 11R, 11G, and R in the order of R, G, and B (color order). 11B is made to emit light. Further, as described above, since the frame frequency is 60 Hz, the controller 20 causes each of the light sources 11R, 11G, and 11B to emit light at a frequency of f0 = 120 Hz (= 60 Hz × 2).

Next, the operation of the projector 1 when performing light source control according to the emission pattern B will be described.
Even when the injection pattern B is selected, the controller 20 controls the panel drive unit 30 in the same manner as when the injection pattern A is selected.
The light source control according to the emission pattern B will be described. As shown in FIG. 5, the controller 20 synchronizes with the writing of the image signals of the R2 field, the G2 field, and the B2 field, as in the case of the emission pattern A. And B light is emitted to the light sources 11R, 11G, and 11B, respectively. However, when the emission pattern B is selected, the controller 20 emits light to each of the light sources 11R, 11G, and 11B at a double speed when the emission pattern A is selected, that is, at a frequency of 2f0 (= 240 Hz). Let it fire. In addition, when the emission pattern B is selected, the controller 20 does not emit light to the light sources 11R, 11G, and 11B in one field as a whole, but turns off the light in the first half period of one field and performs light only in the second half period. Is injected.

  Therefore, in the light source control according to the emission pattern B, as shown in FIG. 5, the controller 20 causes the light source 11R to emit R laser light in the second half period of the R2 field and causes the light source 11G to emit G color in the second half period of the G2 field. Laser light is emitted, and B color laser light is emitted to the light source 11B in the second half of the B2 field. Further, the controller 20 causes the light source 11G to emit G laser light in the second half period of the R1 field, causes the light source 11B to emit B laser light in the second half period of the G1 field, and causes the light source 11R to emit light in the second half period of the B1 field. R laser light is emitted. That is, the controller 20 causes the light sources 11R, 11G, and 11B to emit light that is not synchronized with the writing of the image signal to the pixel 110 in the R1 field, the G1 field, and the B1 field. In order to emit light to the light sources 11R, 11G, and 11B with such an emission pattern, the controller 20 causes the light sources 11R, 11G, and 11B to emit light with a color order different from that of the emission pattern A. .

FIG. 6 is a timing chart showing temporal changes in the display of the field image when the light source control according to the emission pattern B is performed.
As shown in FIG. 6A, when viewed in two fields of the R1 field and the R2 field, the G laser beam is emitted to the pixel 110 during a part of the period, so that the R color and the G color The R field image is displayed by the color mixture. Therefore, the R field image is an image that has changed to the yellow (Y) color side as compared with the case where only the R color light is used. Further, as shown in FIG. 6B, when viewed in two fields of the G1 field and the G2 field, the B color laser light is irradiated to the pixel 110 during a part of the period, so that the G color and the B color are emitted. The G field image is displayed by the color mixture. Therefore, the G field image is an image that has changed to the cyan (C) color side as compared with the case where only the G color light is used. Further, as shown in FIG. 6C, when viewed in two fields of the B1 field and the B2 field, the R color laser light is irradiated to the pixel 110 in a part of the period, so that the B color and the R color are emitted. The B field image is displayed by the color mixture. Therefore, this B field image is an image that has changed to the magenta (M) color side compared to the case where only the B color light is used.

  However, in the R1 field, the G1 field, and the B1 field, since there is a period in which the liquid crystal element 120 is in a transient state, the liquid crystal element 120 is longer than the periods in the R2 field, G2 field, and B2 field in which the liquid crystal element 120 is saturated. The amount of transmitted light is small. Therefore, even when light source control according to the emission pattern B is performed, it is considered that each of the R, G, and B color field images is displayed in a color close to R, G, and B.

When the controller 20 performs light source control according to the emission pattern B, a field image having slightly changed colors from the three primary colors R, G, and B is displayed. Color break-ups are less noticeable. In addition, since the injection pattern B is selected when a black and white pattern mainly including a black and white image is formed, even if the color of the field image has changed from the three primary colors, It is difficult for the observer to perceive the image quality as a deterioration.
Next, a flow of processing executed when the controller 20 determines whether an image formed in one frame is a color pattern or a monochrome pattern and selects an injection pattern will be described.

FIG. 7 is a flowchart showing a flow of processing for selecting an injection pattern.
First, the controller 20 analyzes the input image data R-DATA, G-DATA, and B-DATA, and obtains a histogram of the gradation difference ΔV for each pixel (step S1). Here, the controller 20 calculates the gradation difference ΔV based on the difference between the gradation values of the R, G, and B colors specified by the input image data R-DATA, G-DATA, and B-DATA, A histogram indicating the distribution of the gradation difference ΔV is obtained.

  The gradation difference ΔV has a relatively large value in a pixel that displays a color image, and conversely has a relatively small value in a pixel that displays black and white. For example, in the pixel displaying the R color, the gradation value of the R component is “255” and the gradation values of the G component and the B component are “0”, so the gradation difference ΔV is the maximum “255”. is there. The gradation difference ΔV is “255” even in the pixels displaying the G color and the B color. In the pixel displaying the Y color, the gradation value of the R component and the G component is “255” and the gradation value of the B component is “0”, so the gradation difference ΔV is “255”. On the other hand, in the pixel displaying white, since the gradation values of the R component, G component, and B component are all “255”, the gradation difference ΔV is the minimum “0”. In the pixel displaying black, since the gradation values of the R component, the G component, and the B component are all “0”, the gradation difference ΔV is the minimum “0”.

FIG. 8 is a diagram illustrating an example of a histogram obtained by the process of step S1. When a color pattern is formed, the number of pixels having a relatively large ΔV increases, and for example, a histogram shown in FIG. 8A is obtained. That is, the appearance frequency of pixels having a relatively large ΔV is prominently high. On the other hand, when a monochrome pattern is formed, the number of pixels having relatively small ΔV increases, and for example, a histogram shown in FIG. 8B is obtained. That is, the appearance frequency of pixels with relatively small ΔV is prominently high.
For this reason, the controller 20 can easily determine how many color images and black and white images are included in the image formed on the electro-optical panel 100 by referring to the appearance distribution of ΔV based on the histogram. it can.

The controller 20 determines whether or not the analysis of the histograms of the input image data R-DATA, G-DATA, and B-DATA for one frame has been completed (step S2). If “YES” is determined, the process of step S3 is performed. move on. Then, the controller 20 determines whether or not the gradation difference ΔV having the maximum appearance frequency is larger than the set value (step S3). The set value is a value that serves as an index for determining whether a color image is main or a black-and-white image, and is set in advance, for example, to an experimentally obtained gradation value. If the controller 20 determines that the gradation difference ΔV with the maximum appearance frequency is greater than the set value (step S3; YES), the controller 20 determines that the color pattern and selects the emission pattern A as light source control (step S4). ). On the other hand, when the controller 20 determines that the gradation difference ΔV having the maximum appearance frequency is equal to or less than the set value (step S3; NO), the controller 20 determines that the pattern is a monochrome pattern and selects the emission pattern B as light source control (step S5). The relationship between the gradation difference ΔV histogram and the image pattern described here is merely an example, and the controller 20 may determine the image pattern by another algorithm based on the gradation difference ΔV histogram. .
When the controller 20 executes the process described with reference to FIG. 7 and selects either the injection pattern A or B, the controller 20 performs the control described with reference to FIG. 5 according to the selected injection pattern.
Note that the controller 20 may determine whether the image of all frames is a color pattern or a monochrome pattern, or may make this determination only once for a plurality of frames.

<Modification of First Embodiment>
In the first embodiment described above, the controller 20 selects the emission pattern A or B according to the gradation difference ΔV, but further, the light sources 11R, 11G, and 11B according to the area where the black and white image is formed. Each of the injection times may be changed. Specifically, the controller 20 increases the emission time of the R1 field, the G1 field, and the B1 field with respect to the emission time of light of each color in the R2 field, the G2 field, and the B2 field as the area where the monochrome image is formed is larger. Make the ratio relatively high.

9 and 10 are timing charts showing the operation of the projector 1 according to this modification. 9 and 10 show timing charts showing the operation of the projector 1 corresponding to FIG. 5, but only the first half period of one frame is shown here.
For example, when the maximum frequency of the gradation difference ΔV is equal to or greater than the first threshold value that is larger than the set value, the controller 20 determines that the area where the black and white image is formed is relatively small, and FIG. ), The light emission times of the R1 field, the G1 field, and the B1 field are shortened. On the other hand, when the maximum frequency of the gradation difference ΔV is less than the second threshold value that is smaller than the set value, the controller 20 determines that the area where the black and white image is formed is relatively large, and FIG. As shown in b), the light emission times of the R1 field, G1 field, and B1 field are lengthened.
Here, the controller 20 fixes the light emission times of the R2 field, the G2 field, and the B2 field.

Further, the controller 20 may fix the light emission times of the R1 field, the G1 field, and the B1 field, and change the light emission times of the R2 field, the G2 field, and the B2 field. When the area where the black and white image is formed is relatively small, the controller 20 slightly shortens the emission times of the light in the R2, G2, and B2 fields as shown in FIG. When the area where the black and white image is formed is smaller, the controller 20 further shortens the light emission times in the R2 field, the G2 field, and the B2 field, as shown in FIG. In the case where the light emission times of the R2 field, the G2 field, and the B2 field can be increased, the controller 20 may increase the emission time.
The controller 20 may change the light emission times of the R1, G1, and B1 fields, and the R2, G2, and B2 fields.
According to this modification, the projector 1 emits light of each color to the light sources 11R, 11G, and 11B in an emission time that takes into account the conspicuousness of color breakup according to the area of the black and white image, thereby reducing the image quality. The color breakup can be made inconspicuous while making it difficult for the observer to perceive.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In this embodiment, the number of colors of the image signal written by the panel driving unit 30 is larger than the number of light sources 11R, 11G, and 11B (that is, the number of lights). Specifically, there are three light sources 11R, 11G, and 11B, whereas the panel driving unit 30 performs control for displaying four color field images of R, Y, G, and B colors. Do.

FIG. 11 is a timing chart showing the operation of the projector 1. FIG. 11 is a timing chart corresponding to FIG. 5, and the description of each column is the same as that described in FIG.
When forming a color pattern, the controller 20 selects the injection pattern C. When the injection pattern C is selected, the controller 20 performs the same control as that when the injection pattern A is selected for each field corresponding to the R, G, and B colors, and the field corresponding to the Y color is described below. Control.
When the controller 20 starts the Y1 field following the R2 field, the controller 20 writes the image signal dy1 into the electro-optical panel 100 in the Y1 field in order to display a Y field image corresponding to the Y color. The controller 20 writes the image signal dy2 into the electro-optical panel 100 in the Y2 field following the Y1 field. In addition, the controller 20 turns off the light sources 11R, 11G, and 11B in the Y1 field, emits R light to the light source 11R, and emits G light to the light source 11G over the entire Y2 field. Turn off the light.
That is, in the light source control according to the emission pattern C, the controller 20 causes the light sources 11R, 11G, and 11B to emit light in synchronization with the writing of the image signals of R, Y, G, and B colors.

  When forming a monochrome pattern, the controller 20 selects the injection pattern D. The control of the panel driving unit 30 is performed by the controller 20 in the same manner as when the injection pattern C is selected when the injection pattern D is selected. The light source control according to the emission pattern D will be described. The controller 20 causes the light sources 11R, 11G, and 11B to emit light at double speed when the emission pattern C is selected. When the emission pattern D is selected, the controller 20 turns off the light sources 11R, 11G, and 11B in the first half period of one field, and emits light to one of the light sources 11R, 11G, and 11B only in the second half period. .

  As a result, the controller 20 emits light that is not synchronized with the writing of the image signal in each of the R1 field, the Y1 field, the G1 field, and the B1 field. Furthermore, the controller 20 emits light that is not synchronized with the writing of the image signal in each of the R2 field, the Y2 field, the G2 field, and the B2 field. Thus, when viewed in two continuous fields corresponding to the same color, only the light of the three primary colors R, G, and B is not irradiated to the pixel 110, but the two colors of light are irradiated to the pixel 110. . As a result, color breakup is less noticeable due to the effect of color mixing by time division.

In the case of the second embodiment, the controller 20 emits light that is not synchronized with the writing of the image signal in the R2 field, the Y2 field, the G2 field, and the B2 field. However, the injection pattern D is selected only during the period in which the monochrome pattern is formed. Therefore, regardless of whether or not the controller 20 synchronizes with the writing of the image signals in the R2, Y2, G2, and B2 fields, the controller 20 emits light to the light sources 11R, 11G, and 11B at twice the speed of the emission pattern C. Even if it is ejected, the change in the color of the field image is not easily perceived by the observer as a reduction in image quality.
The panel drive unit 30 writes the image signals corresponding to the four colors R, Y, M, and K, thereby making the color breakfast less noticeable. The reason is that four colors are displayed with the same width as in the case of the three primary colors, so the width per one color is shortened, and the Y color that is not easily perceived by human eyes is included.
In the second embodiment, an example in which an image signal corresponding to the Y color is written in addition to the three colors R, G, and B has been described. However, the controller 20 uses the R, G colors such as the C color and the M color. Also, field images of other colors that can be expressed by a mixed color of B and B light may be generated and displayed.

FIG. 12 is a flowchart showing a process flow when the controller 20 selects an emission pattern based on the gradation difference ΔV.
First, the controller 20 analyzes the input image data R-DATA, G-DATA, and B-DATA, and obtains a histogram of the gradation difference ΔV for each pixel (step S1). When the histogram analysis for one frame is completed (step S2; YES), the controller 20 determines whether the maximum frequency number of pixels having a gradation difference ΔV of “0” (that is, pixels displaying white or black) is less than a set value. It is determined whether or not (step S6). The set value is a value that serves as an index for determining whether a color image is main or a black-and-white image, and is set in advance, for example, to an experimentally obtained gradation value. The larger the area of the black and white image, the higher the frequency of appearance of pixels with a gradation difference ΔV of “0”. If the controller 20 determines that the appearance frequency with the gradation difference ΔV of “0” is less than the set value (step S6; YES), the controller 20 determines the color pattern and selects the emission pattern C (step S7). On the other hand, when the controller 20 determines that the appearance frequency of the gradation difference ΔV is “0” or more (step S6; NO), the controller 20 determines that the pattern is a black and white pattern and selects the emission pattern D (step S8).

[Modification]
The present invention can be implemented in a form different from the above-described embodiment. Further, the following modifications may be combined as appropriate.
In each embodiment described above, the controller 20 analyzes the input image data R-DATA, G-DATA, and B-DATA to obtain a histogram, and forms a color pattern based on the histogram, or a monochrome pattern. Was determined to form. The image pattern may be determined by another determination method, and the controller 20 may determine the pattern based on the distribution of the maximum frequency value, average value, median value, etc. of the gradation difference ΔV. The controller 20 may determine the pattern by dividing the image formed on the electro-optical panel 100 into a plurality of blocks and calculating the gradation difference ΔV for each block. Further, the controller 20 may determine the pattern based on a part of pixels (for example, an area in the center of the screen) instead of all the pixels of one frame of input image data.
Various modifications can be made to the color pattern or monochrome pattern determination algorithm.

In each of the above-described embodiments, the controller 20 arranges the same color field for two colors of R, G, and B in succession. However, the controller 20 may arrange the same color field for three or more fields. . In this case, the controller 20 emits light of each color of R, G, and B so as to synchronize with the writing of the image signal in the second and subsequent fields among the plurality of fields corresponding to the same color.
Further, in the case of performing light source control according to the emission pattern B, the controller 20 forms the color pattern so as to synchronize with the writing of the image signal in the second and subsequent fields among a plurality of fields corresponding to the same color. It is preferable to emit light of each color of R, G, and B at a double speed or higher.
That is, when the monochrome pattern is formed, the controller 20 emits light of two or more colors in a time-division manner within a period of two or more consecutive fields corresponding to the same color, so that the color breakup becomes inconspicuous.

In each of the above-described embodiments, the light source is independent for each of R, G, and B colors. For example, the light source control of each embodiment described above may be performed by configuring the light source of the projector 1 with a combination of a light emitter (for example, a white light source) and a filter disk corresponding to each color of R, G, and B. That is, the present invention does not require that the light source is physically independent for each color.
Further, the color and number of light emitted from the light source and the color components and the number of colors of the field image are merely examples, and may be modified to other colors and the number of colors. The light source of the present invention is not limited to an LED, and may be a solid light source such as a semiconductor laser.

The liquid crystal 105 is not limited to the VA liquid crystal. A liquid crystal other than the VA liquid crystal such as a TN (Twisted Nematic) liquid crystal may be used. The liquid crystal 105 may be a normally white mode liquid crystal.
Further, the liquid crystal element 120 included in the pixel 110 is not limited to the transmissive type, and may be a reflective type.
The present invention is not limited to a device that applies a voltage to a liquid crystal element in accordance with a voltage modulation method, and can also be applied to a device that applies a voltage to a liquid crystal element by a subfield driving method.
The projector 1 may use a reflective liquid crystal panel, an electro-optical element other than liquid crystal such as an organic EL (Electro-Luminescence) panel, or a digital mirror device. The light source is not limited to the LED, and may be a solid light source such as a semiconductor laser.

  The electronic device of the present invention is not limited to a projector. The electronic device of the present invention is a television, a viewfinder type / monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, a word processor, a workstation, a video phone, a POS terminal, a digital still camera, a mobile phone. Examples thereof include a telephone and a device equipped with a touch panel.

DESCRIPTION OF SYMBOLS 1 ... Projector, 11R, 11G, 11B ... Light source, 100 ... Electro-optical panel, 130 ... Scanning line drive circuit, 140 ... Data line drive circuit, 20 ... Controller, 21 ... Image data processing part, 22 ... Timing control part, 23 Analysis unit 24 Light emission control unit 30 Panel drive unit 40R R LED driver 40G G LED driver 40B B LED driver

Claims (9)

A light source that independently emits light of each color of a plurality of colors;
A light modulator including a pixel that modulates light emitted from the light source based on an image signal,
A unit frame for driving the pixels is divided into a plurality of fields, and a first field in which the image signals of the plurality of colors are made to correspond to the same color and a second field following the first field are predetermined. A drive unit arranged in color order and sequentially writing to the pixels;
In the unit frame , when forming a first image having a gradation difference that maximizes the appearance frequency between color components in each pixel greater than a set value ,
Synchronously with the writing of the image signal of the second field, the light of each color of the plurality of colors is emitted to the light source in the color order,
When forming the second image in which the gradation difference is equal to or less than the set value in the unit frame,
A light source control unit that emits the light of each of the plurality of colors to the light source at a speed that is at least twice as fast as when the first image is formed in synchronization with the writing of the image signal of the second field. Drive device for electro-optical device. The light source controller is
The ratio of the emission time of the first field to the emission time of the light of each color of the second field is changed in accordance with the magnitude relationship between the gradation difference that maximizes the appearance frequency and the set value. The drive device for an electro-optical device according to claim 1, wherein The light source controller is
The drive device for an electro-optical device according to claim 2, wherein the ratio is increased when a gradation difference at which the appearance frequency is maximum is less than a threshold smaller than the set value . Analyzing the input image data designating the gradation values of the plurality of colors for each pixel, and comprising an analysis unit for obtaining a histogram of gradation differences of the plurality of colors,
The light source controller is
4. The electro-optical device driving according to claim 2 , wherein a magnitude relationship between a gradation difference at which the appearance frequency is maximum and the set value is determined based on a histogram obtained by the analysis unit. 5. apparatus. The light source is
Emitting light of three colors, a first color, a second color, and a third color;
The drive unit is
The image signal is written to the pixels in a sequence of two fields in the order of the first color, the second color, and the third color,
The light source controller is
When forming the first image,
In the order of the first color, the second color, and the third color, the light source emits light of each color,
When forming the second image,
The light of each color is emitted to the light source at twice the speed when forming the first image in the order of the second color, the third color, and the first color. The drive device for the electro-optical device according to claim 1. When the number of colors of the image signal written by the drive unit is larger than the number of colors of light emitted by the light source,
The light source controller is
When forming the second image, each color of the plurality of colors at a speed that is at least twice as fast as when the first image is formed, regardless of whether or not it is synchronized with the writing of the image signal of the second field. The drive device for an electro-optical device according to claim 1, wherein the light is emitted to the light source. A light source that independently emits light of each color of a plurality of colors;
A light modulator including a pixel that modulates light emitted from the light source based on an image signal, and a driving method of an electro-optical device,
A unit frame for driving the pixels is divided into a plurality of fields, and a first field in which the image signals of the plurality of colors are made to correspond to the same color and a second field following the first field are predetermined. Arranging in color order and sequentially writing to the pixels;
In the unit frame , when forming a first image having a gradation difference that maximizes the appearance frequency between color components in each pixel greater than a set value ,
Synchronously with the writing of the image signal of the second field, the light of each color of the plurality of colors is emitted to the light source in the color order,
When forming the second image in which the gradation difference is equal to or less than the set value in the unit frame,
Synchronizing the writing of the image signal of the second field with the light source to emit the light of each of the plurality of colors to the light source at a speed twice or more that when forming the first image. Device driving method. A light source that independently emits light of each color of a plurality of colors;
A light modulator including a pixel that modulates light emitted from the light source based on an image signal;
A unit frame for driving the pixels is divided into a plurality of fields, and a first field in which the image signals of the plurality of colors are made to correspond to the same color and a second field following the first field are predetermined. A drive unit arranged in color order and sequentially writing to the pixels;
In the unit frame , when forming a first image having a gradation difference that maximizes the appearance frequency between color components in each pixel greater than a set value ,
Synchronously with the writing of the image signal of the second field, the light of each color of the plurality of colors is emitted to the light source in the color order,
When forming the second image in which the gradation difference is equal to or less than the set value in the unit frame,
A light source control unit that emits the light of each of the plurality of colors to the light source at a speed that is at least twice as fast as when the first image is formed in synchronization with the writing of the image signal of the second field. Electro-optic device.   An electronic apparatus comprising the electro-optical device according to claim 8.

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