JP2015038544A - Driving device of electrooptical device, driving method of electrooptical device, electrooptical device, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a reduction in image quality difficult to be perceived by an observer, and make color breakup inconspicuous.SOLUTION: A projector 1 includes: an electrooptical panel 100 that includes pixels modulating light beams of RGB colors emitted from light sources 11R, 11G, and 11B on the basis of image signals; a panel driving unit 30 that divides a unit frame for driving the pixels into a plurality of fields corresponding respectively to any of the RGB colors, and writes image signals of a color component of any of the plurality of colors in the pixels for each field; and a light source control unit 24 that causes the light sources 11R, 11G, and 11B to emit a light beam of a color, of the RGB colors, corresponding to each field, during a period of forming a first image including a color image in each field of the plurality of fields, and causes the light sources 11R, 11G, and 11B to emit light beams of the RGB colors during a period of forming a second image including a black and white image in each field of the plurality of fields.

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. 10, 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.

Further, the color breakup is less noticeable by increasing the frequency of switching the color of the light emitted to the light source. For example, when one set of R, G, and B colors is switched (RGB × 1), two sets (RGB × 2), and four sets (RGB × 4) are compared in one frame. , RGB × 4, RGB × 2, RGB × 1 in this order, the color breakup is less noticeable.
However, the longer the period in which the pixels are irradiated with light that is not synchronized with the writing of the image signal, the greater the change in the color of the field image, and this change in color is likely to be perceived by the observer as a reduction in image quality.
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 drive unit for an optical device, wherein a unit frame for driving the pixel is divided into a plurality of fields, and for each field, a drive unit that writes an image signal of any one of the plurality of colors into the pixels; and When forming a first image including a color image in a unit frame, light of any one of the plurality of colors is emitted to the light source in synchronization with the writing of the image signal for each field. When a second image including a black and white image is formed in the unit frame, light source control for causing the light source to emit light of each color of the plurality of colors during a period in which an image signal of one color component is written to the pixel Part and Obtain.
According to the present invention, when a first image including a color image is formed, light synchronized with writing of an image signal of each color component is emitted to the light source, and a second image including a black and white image is formed. In the period when the image signal of one color component is written, the light of each color of a plurality of colors is emitted to the light source, making it difficult for the observer to perceive the deterioration of the image quality and making the color breakup less noticeable. it can.

In the driving device of the electro-optical device according to the aspect of the invention, the light source control unit may emit the light of each of the plurality of colors to the light source in a time division manner when forming the second image.
According to the present invention, when forming a second image including a black and white image rather than forming a first image including a color image, the frequency of switching the color emitted to the light source is increased. The color breakup can be made inconspicuous while making it difficult for the observer to perceive the deterioration in image quality.

In the driving device of the electro-optical device, the light source control unit may change the emission time of the light of each color in the period according to a region where the black and white image is formed.
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 driving device of the electro-optical device, the light source control unit may shorten the emission time of light of a color corresponding to the one color component 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 driving device of the electro-optical device according to the aspect of the invention, an image data processing unit that performs color conversion processing according to the light emission time of each color on the input image data in which the gradations of the plurality of colors are specified for each pixel. The drive unit may write an image signal having a gradation corresponding to the image data after the color conversion process to the pixel.
According to the present invention, the second image including the black and white image is formed based on the image data subjected to the color conversion process according to the emission time of the light of each color, so that the light that is not synchronized with the writing of the image signal is generated. It is possible to reduce deterioration in image quality due to ejection.

In the drive device for the electro-optical device according to the aspect of the invention, the light source control unit may cause the light sources to simultaneously emit the light of the plurality of colors when forming the second image that satisfies a predetermined condition.
According to the present invention, it becomes easy to form a high-luminance image by simultaneously emitting light of a plurality of colors.

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.

  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.

1 is a plan view showing a configuration of a projector according to an embodiment of the invention. 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 flowchart showing a procedure 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. Explanatory drawing of the color conversion process in the embodiment. 9 is a timing chart showing the operation of a projector according to a second 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.
FIG. 1 is a plan view showing a configuration of a projector according to an 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 an image of one of R, G, and B color components (hereinafter referred to as a “field image”) 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, G, and B colors for each pixel, and a histogram (that is, a gradation difference ΔV). (Frequency distribution). The analysis unit 23 calculates the gradation difference ΔV based on the combination that provides 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 divides one frame into 16 fields. Then, the controller 20 associates the first to fourth fields from the head with the R color, the fifth to eighth fields with the G color, and the ninth to twelfth fields with the B color. The image data DATAw is output with the 13th to 16th fields corresponding to the G color. In the following description, these 16 fields are sequentially assigned to “R1”, “R2”, “R3”, “R4”, “G1”, “G2”, “G3”, “G4”, “B1”. ”,“ B2 ”,“ B4 ”,“ B4 ”,“ G1 ”,“ G2 ”,“ G3 ”,“ G4 ”.

  Further, the controller 20 determines the pattern of the image formed in one frame based on the histogram of the gradation difference ΔV. The processing related to this determination will be described later, but the controller 20 performs light source control according to the emission pattern A when determining that the color pattern is a color pattern (an example of the first image) mainly. When it is determined that the color + monochrome pattern (an example of the second image) in which the color image and the monochrome image are appropriately mixed, the controller 20 performs light source control according to the emission pattern B. 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 C is performed. The color + monochrome pattern indicates an image in which color objects are arranged on a white or black background, for example. The black-and-white pattern indicates an image in which, for example, white or black is used as a background and objects of the other color are arranged, as illustrated in FIG. In each of the emission patterns A, B, and C, 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 the controller 20 starts the R1 field, which is the first field, the controller 20 controls the panel drive unit 30 to write the image signal dr1 for displaying the R field image to 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, which is the second field, the controller 20 controls the panel drive unit 30 to write the image signal dr2 for displaying the R field image into 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.
The controller 20 controls the panel drive unit 30 so that the image signals dr3 and dr4 for displaying the R field image are sequentially written to the pixels in the R3 and R4 fields which are the third and fourth fields following the R2 field. . The controller 20 also controls the electro-optical panel 100 so that the same field image as the R2 field is displayed in the R3 field and the R4 field. The controller 20 causes the light source 11R to emit light of R color over the entire R3 field and R4 field, and turns off the light sources 11G and 11B.

Subsequently, the operation related to the G1 to G4 fields of the fifth to eighth fields will be described, but the operation related to the R color in the R1 to R4 fields is substantially the same as the operation in which the G color is replaced.
That is, the controller 20 sequentially writes the image signals dg1, dg2, dg3, and dg4 in the electro-optical panel 100 in the G1 to G4 fields in order to display the G field image. Further, the controller 20 turns off the light sources 11R, 11G, and 11B in the G1 field, causes the light source 11G to emit G light over the entire G2 to G4 fields, and turns off the light sources 11R and 11B.

Subsequently, the operation related to the B1 to B4 fields which are the ninth to twelfth fields will be described, but the operation related to the G color in the G1 to G4 fields is substantially the same as the operation in which the B color is replaced.
That is, the controller 20 sequentially writes the image signals db1, db2, db3, and db4 in the electro-optical panel 100 in the B1 to B4 fields in order to display the B field image. Further, the controller 20 turns off the light sources 11R, 11G, and 11B in the B1 field, emits light of B color to the light source 11B, and turns off the light sources 11R and 11G over the entire B2 to B4 fields.
The controller 20 performs the same control as the G1 to G4 fields of the fifth to eighth fields in the G1 to G4 fields of the thirteenth to sixteenth fields.

  As described above, when the injection pattern A is selected, the controller 20 writes the image signal of each color component to the pixel 110 in the order of R, G, B, and G colors in one frame, and the image signal The light sources 11R, 11G, and 11B are caused to emit light in synchronization with the writing. 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. For this reason, when fields are arranged in the color order of R, G, B, and G in one frame, the controller 20 similarly uses the light sources 11R, 11G, and R in the color order of R, G, B, and G colors. 11B is made to emit light. Further, since the frame frequency is 60 Hz as described above, the controller 20 emits light at a frequency of 240 Hz (= 60 Hz × 4) to each of the light sources 11R, 11G, and 11B.

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 uses the light of the color synchronized with the writing of the image signal in the period of two fields among the four consecutive fields corresponding to the same color. In a period of one field, light that is not synchronized with the writing of the image signal is emitted.

  Specifically, the controller 20 turns off all of the light sources 11R, 11G, and 11B in the R1 field, and causes the light source 11R to emit R light over the entire R2 and R3 fields. Then, the controller 20 causes the light source 11G to emit G light in the first half period of the R4 field, and causes the light source 11B to emit B light in the second half period of the R4 field. Further, the controller 20 turns off all of the light sources 11R, 11G, and 11B in the G1 field, and causes the light source 11R to emit R light in the first half period of the G2 field. Then, the controller 20 causes the light source 11G to emit G light over the entire period from the second half period of the G2 field to the first half period of the G4 field, and causes the light source 11B to emit B color light over the second half period of the G4 field. Further, the controller 20 turns off all the light sources 11R, 11G, and 11B in the B1 field, emits R light to the light source 11R in the first half period of the B2 field, and emits G light to the light source 11G in the second half period of the B2 field. Light is emitted. Then, the controller 20 causes the light source 11B to emit light of B color over the entire B3 field and B4 field.

That is, the controller 20 time-divides all light of R, G, and B colors in each of the period composed of the R1 to R4 fields, the period composed of the G1 to G4 fields, and the period composed of the B1 to B4 fields. Light is emitted to the light sources 11R, 11G, and 11B. Therefore, when viewed in four consecutive fields corresponding to the same color, a field image having a color slightly changed from the three primary colors R, G, and B is displayed. Therefore, the color breakup is less noticeable than when the injection pattern A is selected.
However, when light source control according to the emission pattern B is performed, a change in the color (hue) of the field image may be perceived by the observer as a reduction in image quality. For this reason, the image data processing unit 21 of the controller 20 forms an image on the electro-optical panel 100 based on the image data DATAw subjected to color conversion processing described later. Details of the color conversion process will be described later.

Next, the operation of the projector 1 when performing light source control according to the emission pattern C will be described.
Even when the ejection pattern C is selected, the controller 20 controls the panel drive unit 30 in the same manner as when the ejection patterns A and B are selected. The light source control according to the emission pattern C will be described. As shown in FIG. 5, the controller 20 emits light of a color synchronized with the writing of the image signal in a period of one field out of four fields corresponding to the same color. On the other hand, light that is not synchronized with the writing of the image signal is emitted during the period of two fields. That is, when the emission pattern C is selected, the controller 20 makes the time for emitting light not synchronized with the writing of the image signal longer than that for the emission pattern B.

  Specifically, the controller 20 turns off all of the light sources 11R, 11G, and 11B in the R1 field, and causes the light source 11R to emit R light in the R2 field. Then, the controller 20 causes the light source 11G to emit G light in the R3 field, and causes the light source 11B to emit B light in the R4 field. Further, the controller 20 turns off all the light sources 11R, 11G, and 11B in the G1 field, and causes the light source 11R to emit R light in the G2 field. Then, the controller 20 causes the light source 11G to emit G light in the G3 field, and causes the light source 11B to emit B light in the G4 field. The controller 20 turns off all of the light sources 11R, 11G, and 11B in the B1 field, and causes the light source 11R to emit R light in the B2 field. Then, the controller 20 causes the light source 11G to emit G-color light in the B3 field, and causes the light source 11B to emit B-color light in the B4 field.

That is, the controller 20 uses the same light emission time for each color of R, G, and B in each of the period including the R1 to R4 fields, the period including the G1 to G4 fields, and the period including the B1 to B4 fields ( In other words, each light is emitted in a time-sharing manner. Since the emission pattern C is selected when a black and white pattern is formed, even if color mixing due to time division of light of each color of R, G, and B occurs, it is perceived by the observer as a reduction in image quality. It is hard to be done. When the injection pattern C is selected, a field image having a color slightly changed from the three primary colors R, G, and B is displayed when viewed in four consecutive fields corresponding to the same color, and The switching frequency is higher than in the case of the injection pattern B. For this reason, even when there is a situation in which color breakup is more noticeable than in the case of color + monochrome pattern when forming a black and white pattern, the color breakup is less noticeable.
As described above, when the controller 20 forms a color + monochrome pattern including a black and white image or a black and white pattern image, the controller 20 emits light of each color of R, G, and B in a period for writing an image signal of one color component. Let the light source emit. Further, the controller 20 relatively shortens the light emission time synchronized with each field as the area of the black and white image increases, and sets the ratio of the light emission times of the respective colors to R: G: B = 1: 1. : 1. By this light source control, the color breakup is less noticeable while suppressing the deterioration of the image quality of the image formed by the field sequential drive.

  By the way, when performing light source control according to the emission pattern B, the hue of a color image may change due to the presence of a period during which light that is not synchronized with image signal writing is emitted. Therefore, in the controller 20, the image data processing unit 21 outputs the image data DATAw subjected to the color conversion processing for suppressing the change in hue to the panel driving unit 30.

FIG. 6 is a diagram illustrating the color conversion process.
FIG. 6A is a graph showing a color gamut that can be expressed in the case of the emission pattern A and a color gamut that can be expressed in the case of the emission pattern B on a chromaticity diagram (CIE1931). In this graph, the horizontal axis represents the x value, and the vertical axis represents the y value.
When the ejection pattern A is selected, RGB gradations can be expressed within the color gamut indicated by the solid line in FIG. 6, whereas when the emission pattern B is selected, within the color gamut indicated by the broken line in FIG. 6. Thus, RGB gradations are expressed. However, since the color gamut of the LED is wider than the color gamut of sRGB, the reduction of the color gamut itself does not cause much problem in gradation expression. However, when a certain gradation is to be expressed, if the same image signal is written to the pixel when the ejection pattern A is selected and when the ejection pattern B is selected, each emission pattern is within the color gamut of the gradation. May be perceived by the observer as a degradation in image quality. Therefore, the image data processing unit 21 does not change the point P even when the hue changes from the point P to the point Pc in FIG. 6A due to the change in the light source control from the emission pattern A to the emission pattern B, for example. A color conversion process is performed so that gradation can be expressed with a hue corresponding to. That is, the image data processing unit 21 performs color conversion processing to reduce the difference in hue of the color image between when the ejection pattern A is selected and when the ejection pattern B is selected.

  FIG. 6B shows an example of color conversion processing. For example, in the case of the emission pattern A, the relative transmittance of the liquid crystal element 120 is set to 20% for the R color, the relative transmittance of the liquid crystal element 120 is set to 90% for the G color, and the relative transmittance of the liquid crystal element 120 is set to the B color. Consider a case where gradation is expressed as 20%. If the same gradation is to be expressed by the emission pattern B, the color conversion processing is performed to reduce the relative transmittance for the G and B colors by increasing the emission time of the G and B light. It's fine. In this example, when the emission pattern B is selected, the relative transmittance of the liquid crystal element 120 for R color is 0%, the relative transmittance of the liquid crystal element 120 for G color is 100%, and the relative transmittance of the liquid crystal element 120 for B color. The rate is 0%.

  The image data processing unit 21 stores in advance color conversion parameters for changing the relative transmittance (that is, hue) of the liquid crystal element 120 in accordance with the selected emission pattern, as illustrated in FIG. 6B. Keep it. For example, the image data processing unit 21 stores the color conversion parameter in association with the combination of gradation values specified by the input image data R-DATA, G-DATA, and B-DATA. Then, the image data processing unit 21 performs color conversion processing on the input image data R-DATA, G-DATA, and B-DATA using conversion parameters corresponding to the emission pattern used in the light source control, and converts the image data DATAw into Generate and output. The color conversion parameter is typically a parameter for changing the gradation value designated by the input image data R-DATA, G-DATA, and B-DATA. As an example of color conversion processing, the image data processing unit 21 performs color conversion processing that changes an image signal that is not synchronized with the color emitted by the light source in a direction that lowers the relative transmittance (for example, 0%). . Further, the image data processing unit 21 may perform color conversion processing that increases the degree of lowering the relative transmittance as the emission time of light that is not synchronized with the writing of the image signal becomes longer.

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 appearance frequency of pixels having a relatively large gradation difference ΔV is prominently high, and for example, a histogram shown in FIG. 8A is obtained. In this case, the maximum frequency of the gradation difference ΔV exists in the high gradation range a. When a color + monochrome pattern is formed, the appearance frequency of pixels having a relatively small gradation difference ΔV increases, and for example, a histogram shown in FIG. 8B is obtained. In this case, the appearance frequency of the gradation difference ΔV is high in each of the high gradation range a and the low gradation range b. When a black-and-white pattern is formed, the appearance frequency of pixels with relatively small ΔV increases and, for example, a histogram shown in FIG. 8C is obtained. In this case, the maximum frequency of the gradation difference ΔV exists in the low gradation range b.
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 an image pattern based on the histogram of the gradation difference ΔV (step S3). For example, if the maximum frequency of the gradation difference ΔV is included in the high gradation range a and the value of the maximum frequency is equal to or greater than the set value, the controller 20 determines that the color pattern (step S3; color pattern). The injection pattern A is selected (step S4). For example, when the maximum frequency of the gradation difference ΔV is included in the low gradation range b and the value of the maximum frequency is greater than or equal to the set value, the controller 20 determines that the pattern is a monochrome pattern (Step S3; monochrome pattern) ), The injection pattern C is selected (step S5). For example, if neither the color pattern nor the black and white pattern is present, the controller 20 determines that it is a color + monochrome pattern (step S3; color + monochrome pattern) and selects the ejection pattern B (step S6). The relationship between the histogram of the gradation difference ΔV 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 histogram of the gradation difference ΔV.
When the controller 20 executes the process described with reference to FIG. 7 and selects one of the injection patterns A, B, or C, 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 the image pattern for all frames of the image, or may determine the image pattern only once for a plurality of frames.

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 the above-described embodiment, the controller 20 emits light of each color of R, G, and B to the light source in a time-division manner during the period in which the image signal of one color component is written when forming a monochrome pattern. It was. Instead of this, the controller 20 may emit light of each color of R, G, and B at the same time in a period in which an image signal of one color component is written.

FIG. 9 is a timing chart showing the operation of the projector 1. FIG. 9 shows operations related to image formation of one frame of the projector 1, and the description of each column is the same as that described in FIG.
The controller 20 performs light source control according to the emission patterns A and B by the same method as in the above-described embodiment. Further, the controller 20 performs light source control with the emission pattern D instead of the emission pattern C. As shown in FIG. 9, when the emission pattern D is selected, the controller 20 emits light of each color of R, G, and B simultaneously over the entire period of one frame. Even when such light is emitted, the image to be formed is mainly a black-and-white image, so the color change is not easily perceived by the observer.

When this emission pattern D is adopted, the controller 20 reduces the current supplied to the light sources 11R, 11G, and 11B as compared with the selection of the emission patterns A and B so that the white display does not become too bright. The luminance may be reduced.
In addition, the controller 20 may perform light source control using the emission patterns C and D together. For example, the controller 20 selects the ejection pattern C when the maximum frequency value of the histogram of the gradation difference ΔV is less than the threshold value in the gradation range C, and selects the ejection pattern D when the value is equal to or greater than the threshold value. To do. That is, the controller 20 selects the injection pattern D when forming an image including a black and white image that satisfies a predetermined condition.

  In the embodiment described above, the controller 20 analyzes the input image data R-DATA, G-DATA, and B-DATA to obtain a histogram, and determines an image pattern based on the histogram. The determination of the image pattern may be performed by another determination method. For example, the controller 20 may determine the image pattern based on the distribution of the maximum frequency value, average value, median value, etc. of the gradation difference ΔV. Good. Further, the controller 20 may divide the image formed on the electro-optical panel 100 into a plurality of blocks, calculate the gradation difference ΔV for each block, and determine the image pattern. Further, the controller 20 may determine the image pattern based on some pixels (for example, a region in the center of the screen) instead of all the pixels of one frame of input image data.

  In the embodiment described above, the controller 20 performs three types of light source control of the emission patterns A, B, and C, but may perform two types or four or more types of light source control. Regardless of the number of types of emission patterns, the controller 20 changes the emission time of light of each color of R, G, and B according to the area where the black and white image is formed. In particular, the larger the black and white image area, the shorter the light emission time synchronized with the writing of the image signal, and the higher the color switching frequency. For example, the controller 20 determines the ratio of the R, G, and B emission times in the period in which the image signal of one color component is written as the area of the black and white image is larger, R: G: B = 1: 1. : 1.

In the above-described embodiment, the controller 20 writes the image signal with four consecutive fields of the same color for each color of R, G, and B, but the same color field is written in three fields or less or five fields or more. It may be continuous.
Also in this case, when forming an image including a black and white image, the controller 20 may emit light of each color of R, G, and B in a period in which an image signal of one color component is written.
Further, the projector 1 is not limited to the three colors of R, G, and B, and image signals corresponding to the colors of yellow, cyan, and magenta may be written to the pixels 110. Even in this case, the projector 1 can generate and display a field image using light that is synchronized with writing of an image signal by mixing R, G, and B light.

  In the above-described embodiment, the light sources are independent for each of R, G, and B colors. For example, the light source of the projector 1 may be configured by a combination of a light emitter (for example, a white light source) and a filter disc corresponding to each color of R, G, and B, and the light source control of each embodiment described above may be performed. . That is, the present invention does not require that the light source is physically independent for each color.

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 (10)

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 drive unit that divides a unit frame for driving the pixels into a plurality of fields, and writes an image signal of any one of the plurality of colors into the pixels for each field;
When forming a first image including a color image in the unit frame,
In synchronism with the writing of the image signal for each field, the light source emits light of any one of the plurality of colors of light,
When forming a second image including a black and white image in the unit frame,
A drive device for an electro-optical device, comprising: a light source control unit that emits light of each of the plurality of colors to the light source in a period in which an image signal of one color component is written to the pixel. The light source controller is
The electro-optical device driving device according to claim 1, wherein when forming the second image, the light of each of the plurality of colors is emitted to the light source in a time-sharing manner. The light source controller is
The electro-optical device driving device according to claim 2, wherein an emission time of the light of each color in the period is changed according to a region where the monochrome image is formed. The light source controller is
The electro-optical device drive device according to claim 3, wherein the larger the region, the shorter the light emission time of the color corresponding to the one color component. An image data processing unit that performs color conversion processing according to the light emission time of each color on the input image data in which the gradations of the plurality of colors are specified for each pixel;
The drive unit is
5. The electro-optical device driving device according to claim 3, wherein an image signal having a gradation corresponding to the image data after the color conversion processing is written to the pixel. The light source controller is
When forming the second image satisfying a predetermined condition,
The drive device for an electro-optical device according to claim 1, wherein the light of the plurality of colors is simultaneously emitted to the light source. 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
The electro-optical device drive device according to claim 1, wherein an area in which the black and white image is formed is determined based on a histogram obtained by the analysis unit. 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,
Dividing a unit frame for driving the pixel into a plurality of fields, and writing an image signal of any one of the plurality of colors into the pixels for each field;
When forming a first image including a color image in the unit frame,
In synchronism with the writing of the image signal for each field, the light source emits light of any one of the plurality of colors of light,
When forming a second image including a black and white image in the unit frame,
And a step of causing the light source to emit light of each of the plurality of colors in a period in which an image signal of one color component is written to the pixel. 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 drive unit that divides a unit frame for driving the pixels into a plurality of fields, and writes an image signal of any one of the plurality of colors into the pixels for each field;
When forming a first image including a color image in the unit frame,
In synchronism with the writing of the image signal for each field, the light source emits light of any one of the plurality of colors of light,
When forming a second image including a black and white image in the unit frame,
An electro-optical device comprising: a light source control unit that emits light of each of the plurality of colors to the light source in a period in which an image signal of one color component is written into the pixel.   An electronic apparatus comprising the electro-optical device according to claim 9.

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