JP2008042515A - Video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video display device that makes a viewer not perceive a color break phenomenon while reducing power consumption. <P>SOLUTION: The video display device comprises a light source unit 171 having a plurality of monochromatic light sources emitting light of different wavelength on a time-division basis; a spatial modulating element 151 which generates an image by modulating the light beams emitted by the light source unit 171; an image display unit 172 which displays the image that the spatial modulating element 151 generates by modulating the light emitted by the light source unit 171; a color break predicting unit 111 which calculates a timing coefficient for not generating color-break phenomenon from luminance information of input video; a controlled variable calculating unit 112 which calculates a control coefficient for designating control conditions of the light sources and spatial modulating element 151 from the timing coefficient; a light source driver 131 which controls driving of the light sources based upon the control coefficient; and a spatial modulating element control unit 132 which controls the spatial modulating element 151 based upon the control coefficient. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video display device, and more particularly to a technique for reducing power consumption while maintaining the degree of recognition of a color break phenomenon.

  2. Description of the Related Art In recent years, attention has been paid to color image display devices that display color images with additive color mixing using a time-division driving method. In such a color video display device, since one pixel is one picture element, there is an advantage that a resolution three times that of a color video display device that performs juxtaposed color mixing can be obtained. In one of such time-division driving type color image display devices, R (red), G (green), and B (blue) color lights generated through a color filter that rotates light from a white light source are time-series. There is known a method of displaying a color image by irradiating a spatial modulation element and projecting color light reflected or transmitted by the spatial modulation element on a screen. In addition to this, R (red), G (green), and B (blue) monochromatic light sources are irradiated onto the spatial modulation element in time series, and the color light reflected or transmitted by the spatial modulation element is projected onto the screen. There is also a method for displaying color images.

  It has been known that a color break phenomenon is likely to occur in a time division drive type color image display apparatus in the case of an image using a high contrast or an image having a large luminance change amount at an edge portion. As a method of suppressing this color break phenomenon, by increasing the rotation speed of the color filter or changing the color arrangement of the color filter, the time difference between the three color lights is reduced to physically narrow the color bunt width. , It is known that it can be perceived.

A conventional color filter and light irradiation method will be described with reference to FIGS.
FIG. 7A is a normal color filter that rotates 60 frames per second, and the color filter rotates once per frame. The color filter is divided into R, G, and B, and is irradiated through this color filter. As shown in FIG. 8A, R, G, and B are irradiated once each time. In FIG. 7B, by dividing and arranging G, R, G, B, B, G, and R are irradiated as shown in FIG. 8B. In FIG. 7C, by arranging R, G, and B twice, R, G, B, R, G, and B are irradiated as shown in FIG. In this manner, the color break phenomenon is prevented from being perceived by shortening the interval at which one color is irradiated. (For example, refer to Patent Document 1.)
JP-A-8-51633 (page 8, FIG. 4)

  However, in the conventional configuration, the number of times of controlling the spatial modulation element is increased by physically narrowing the color band width. Accordingly, there is a problem that power consumption for control increases.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a video display apparatus that reduces power consumption and prevents a color break phenomenon from being perceived.

  In order to solve the above-described conventional problems, an image display device according to the present invention includes a light source unit having a plurality of monochromatic light sources each emitting light of different wavelengths in a time division manner, and light emitted from the light source unit. A spatial modulation element that generates an image by modulating the light, an image display unit that displays an image obtained by modulating the light emitted from the light source unit by the spatial modulation element, and a color break phenomenon from luminance information of the input video A color break prediction unit that predicts occurrence and calculates a timing coefficient at which the color break phenomenon does not occur, and a control amount calculation that calculates a control coefficient for instructing control conditions for the light source and the spatial modulation element from the timing coefficient A light source driving unit that controls driving of the light source based on the control coefficient, and a spatial modulation element control unit that controls the spatial modulation element based on the control coefficient. And it is characterized in and.

  Furthermore, in the video display device, the monochromatic light source is an LED light source or a laser light source.

  Further, in the video display device, the spatial modulation element control unit controls a reflective or transmissive spatial modulation element.

  Further, in the video display device, the light source unit includes a plurality of single-color light sources that emit light of different wavelengths, a light combining unit that combines light emitted from the plurality of light sources, and light that is synthesized by the light combining unit. It is comprised by the incident optical unit which injects into an element, It is characterized by the above-mentioned.

  Furthermore, in the video display device, the image display unit includes a projection optical unit and an image display unit that displays an image projected by the projection optical unit.

  Further, in the video display device, the color break prediction unit includes a luminance measurement unit that calculates contrast from the input video, an edge detection unit that calculates edge strength from the input video, and the timing coefficient from the contrast and edge strength. And a timing coefficient calculation unit that calculates

  Furthermore, in the video display device, the edge strength is a maximum value of a difference in luminance from the periphery of the edge.

  Further, in the video display device, the light source driving unit sets a light emission order, a light emission interval, and a light emission number of the monochromatic light source from the control coefficient.

  Furthermore, in the video display device, the spatial modulation element control unit sets a control order, a control interval, and a control count for each constituent color from the control coefficient.

  As described above, according to the first aspect of the present invention, the driving of the light source and the spatial modulation element is changed so that the color break does not occur in the case of the input signal in which the color break occurs. It is possible to prevent the color break phenomenon from being perceived while reducing power.

  Embodiments of a video display apparatus according to the present invention will be described below in detail with reference to the drawings.

  In the following, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a system configuration diagram of a video display apparatus according to a first embodiment of the present invention. In FIG. 1, a monochromatic light source 142 is a plurality of light sources that independently emit light of different wavelengths at arbitrary timing. In this embodiment, the monochromatic light source 142 is three LED light sources or laser light sources that emit light by R, G, and B. The light combining unit 141 combines light emitted from the monochromatic light source 142. In this embodiment, a dichroic prism is used. The synthesized light 125 is light synthesized by the dichroic prism 141. The spatial modulation element 151 creates an image by modulating the emitted light. The incident optical unit 161 is an optical unit that makes the combined light 125 incident on the spatial modulation element 151. Incident light 126 is applied to the spatial modulation element 151. The light source unit 171 includes a monochromatic light source 142, a light combining unit 141, and an incident optical unit 161. The output image 127 is formed by light in which the incident light 126 is reflected or transmitted by the spatial modulation element 151. The screen 163 displays the output video 127. The projection optical unit 162 is an optical unit that projects the output video 127 onto the screen 163. The image display unit 172 includes a projection optical unit 162 and a screen 163. The light source driving unit 131 drives the monochromatic light source 142. The spatial modulation element control unit 132 controls the modulation of the spatial modulation element 151. The spatial modulation element control signal 124 is a signal for controlling the spatial modulation element 151. The control coefficient 123 is a coefficient for controlling the light source driving unit 131 and the spatial modulation element control unit 132. An input video 101 is a video input to the system from the outside. The timing coefficient 121 is a coefficient calculated from the contrast and edge information of the input video 101. The color break prediction unit 111 calculates a timing coefficient 121 from the input video 101. The control amount calculation unit 112 calculates the control coefficient 123 from the timing coefficient 121.

  FIG. 5 shows the characteristics of color break recognition. The degree of recognition in FIG. 5 indicates the degree of recognition of a color break by showing images of high and low brightness and edge strength to a plurality of subjects. The higher the degree of recognition, the more subjects who have recognized a color break. Represents that. As shown in FIG. 5, it is easy to recognize a video using high luminance (FIG. 5 a) or a video with a large luminance change amount at the edge (FIG. 5 b). In other words, it is difficult to recognize the color break phenomenon when the image has a low luminance or the luminance change amount of the edge portion is small. The present invention utilizes this characteristic to control the irradiation timing of the monochromatic light source 142 and the modulation of the spatial modulation element 151, which were conventionally fixed speeds.

  Hereinafter, a specific example of the present invention will be described using a procedure for acquiring an image from an input video and projecting it on a screen.

  In the first embodiment, the input video 101 will be described as being composed of three colors of R, G, and B, and having luminance of each color 256. Here, the input video may use colors other than R, G, and B and colors other than 256 luminance. The light source 142 may be an LED light source or a laser light source.

  First, the input video 101 is input by the color break prediction unit 111 and outputs a timing coefficient 121 from the luminance and the edge.

  FIG. 2 is a detailed configuration diagram of the color break prediction unit 111. The luminance measuring unit 201 measures the luminance of all pixels of the input video 101 and calculates the difference between the highest luminance and the lowest luminance. The edge detection unit 202 detects the edge of the input video 101 and outputs the maximum edge strength. The contrast 211 is calculated by the luminance measurement unit 201. The edge strength 212 is calculated by the edge detection unit 202. The timing coefficient calculation unit 203 outputs a timing coefficient 121 from the contrast 211 and the edge strength 212.

The luminance measurement unit 201 calculates the luminance component Y of all pixels of the input video 101 and outputs the difference between the calculated maximum luminance and the minimum luminance as the contrast 211. As a method for calculating the luminance component Y, for example, the digital video component standard ITU-R BT. The luminance component Y is calculated by (Equation 1) using the conversion formula of the YCbCr coordinate system established in 601.
Here, the luminance of R is R_c, the luminance of G is G_c, and the luminance of B is B_c.

次に、エッジ検出部２０２は、入力映像１０１の各画素についてエッジ成分を算出して、全画素中で最大のエッジ成分をエッジ強度２１２として出力する。エッジ成分の算出方法としては、例えば（数２）に示すように、中心の輝度成分から周辺の輝度成分を引いた値の絶対値にて算出できる。
ここで、図６に示すように、中心の輝度成分をＹとし、周辺の輝度成分をＡからＨとする。

Next, the edge detection unit 202 calculates an edge component for each pixel of the input video 101 and outputs the maximum edge component among all the pixels as the edge strength 212. As an edge component calculation method, for example, as shown in (Expression 2), it can be calculated by an absolute value of a value obtained by subtracting a peripheral luminance component from a central luminance component.
Here, as shown in FIG. 6, the central luminance component is Y, and the peripheral luminance components are A to H.

次に、出力されたコントラスト２１１とエッジ強度２１２を用いて、タイミング係数算出部２０３にてタイミング係数１２１を作成する。図３、図４そして表１を用い説明する。

Next, using the output contrast 211 and edge strength 212, the timing coefficient calculation unit 203 creates a timing coefficient 121. This will be described with reference to FIGS. 3 and 4 and Table 1. FIG.

  3 is an irradiation diagram of the monochromatic light source 142. FIG. 3 (a) is a 1 × speed, FIG. 3 (b) is a 2 × speed, FIG. 3 (c) is a 3 × speed, and FIG. 3 (d) is a 4 × speed irradiation. At 1 × speed (a), R • G • B is irradiated once per frame, and at 2 × speed (b), R • G • B is irradiated twice per frame. Similarly, irradiation is performed 3 times at 3 times speed (c), and irradiation is performed 4 times at 4 times speed (d). 4A and 4B are modulation control diagrams of the spatial modulation element 151. FIG. 4A is 1 × speed, FIG. 4B is 2 × speed, FIG. 4C is 3 × speed, and FIG. 4D is 4 × speed. In the 1 × speed (a), R · G · B is controlled once per frame, and in the 2 × speed (b), R · G · B is controlled twice per frame. At the triple speed (c), control is performed three times, and at the quadruple speed (d), control is performed four times. In the present embodiment, the description will be made assuming that the maximum speed is 4 times.

  Table 1 is a table for calculating the control coefficient 123 for controlling the monochromatic light source 142 and the spatial modulation element 151. Table 1 (a) is a brightness coefficient table, and the brightness coefficient is calculated from the contrast 211. The luminance coefficient is a coefficient for calculating the timing coefficient 121 that sets the driving speed of the monochromatic light source 142 and the control speed of the spatial modulation element 151. For contrast 211, the minimum speed required to prevent color breaks from occurring is shown. The same applies to the edge intensity table of Table 1 (b). The edge intensity coefficient is a coefficient for calculating the timing coefficient 121 for setting the driving speed of the monochromatic light source 142 and the control speed of the spatial modulation element 151, and the edge intensity 212. On the other hand, the minimum required double speed is shown so that no color break occurs.

タイミング係数算出部２０３では、コントラスト２１１と表１（ａ）輝度係数テーブルから輝度係数を算出し、エッジ強度２１２と表１（ｂ）からエッジ強度係数を算出する。そして、輝度係数とエッジ強度係数を足してタイミング係数１２１として出力する。

The timing coefficient calculation unit 203 calculates a luminance coefficient from the contrast 211 and Table 1 (a) luminance coefficient table, and calculates an edge intensity coefficient from the edge intensity 212 and Table 1 (b). Then, the luminance coefficient and the edge strength coefficient are added and output as a timing coefficient 121.

  The control amount calculation unit 112 divides the timing coefficient 121 by 2 and outputs the rounded up value as the control coefficient 123. The control coefficient 123 means that the monochromatic light source 142 and the spatial modulation element 151 are controlled at 1 × speed, 2 at 2 × speed, 3 at 3 × speed, and 4 at 4 × speed.

  The light source driving unit 131 changes the light emission speed and the number of light emission of the light source 142 by the control coefficient 123. Similarly, the spatial modulation element control unit 132 changes the control speed and the number of times of control of the spatial modulation element 151 by the control coefficient 123.

  Next, the monochromatic light source 142 is combined on the same optical axis by the dichroic prism 141 to become combined light 125. The incident optical unit 161 converts the combined light 125 into incident light 126 and makes it incident on the spatial modulation element 151. The spatial modulation element 151 converts the incident light 126 into an output image 127 by being reflected or transmitted by the spatial modulation element control signal 124 and displayed on the screen 163 via the projection optical unit 162.

  Thus, by calculating the control speed from the luminance and edge of the input video 101 and controlling the monochromatic light source 142 and the spatial modulation element 151, it is possible to drive with a lower current consumption than when driving at a constant double speed.

  As described above, in the first embodiment, the control coefficient 123 is calculated from the input video 101, and the driving speeds of the monochromatic light source 142 and the spatial modulation element 151 are controlled by the calculated control coefficient 123, so that the color break It is effective in reducing power consumption while maintaining the degree of recognition of the phenomenon.

  Further, since it can be driven at a low speed, there is an effect of reducing the occurrence of a surge current that is a cause of malfunction or element deterioration.

  The video display device according to the present invention is useful as a display that does not cause a color break phenomenon with low power consumption.

1 is a system configuration diagram of a video display device according to a first embodiment of the present invention. 1 is a configuration diagram of a color break prediction unit of a video display device in Embodiment 1 of the present invention. The figure which shows light source irradiation in Example 1 of this invention The figure which shows the spatial modulation element control in Example 1 of this invention Figure showing color break recognition experiment results Diagram showing edge component calculation The figure which shows the color filter in a prior art example The figure which shows the irradiation timing in the conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Input video 111 Color break prediction part 112 Control amount calculation part 121 Timing coefficient 123 Control coefficient 124 Spatial modulation element control signal 125 Synthetic light 126 Incident light 127 Output video 131 Light source drive part 132 Spatial modulation element control part 141 Photosynthesis unit 142 Monochromatic light source 151 Spatial Modulation Element 161 Incident Optical Unit 162 Projection Optical Unit 163 Screen 171 Light Source Unit 172 Image Display Unit 201 Luminance Measuring Unit 202 Edge Detection Unit 203 Timing Coefficient Calculation Unit 211 Contrast 212 Edge Strength

Claims (9)

A light source unit having a plurality of monochromatic light sources each emitting light of different wavelengths in a time-sharing manner;
A spatial modulation element that modulates the light emitted from the light source unit to create an image;
An image display unit for displaying an image obtained by modulating the light emitted from the light source unit by the spatial modulation element;
A color break prediction unit that predicts occurrence of a color break phenomenon from luminance information of an input video and calculates a timing coefficient at which the color break phenomenon does not occur;
A control amount calculation unit for calculating a control coefficient for instructing a control condition of the light source and the spatial modulation element from the timing coefficient;
A light source driving unit that controls driving of the light source based on the control coefficient;
An image display device comprising: a spatial modulation element control unit that controls the spatial modulation element based on the control coefficient. The image display apparatus according to claim 1, wherein the monochromatic light source is an LED light source or a laser light source. The video display device according to claim 1, wherein the spatial modulation element control unit controls a reflective or transmissive spatial modulation element. The light source unit is
A plurality of monochromatic light sources that emit light of different wavelengths;
A light combining unit that combines light emitted from the plurality of light sources;
An incident optical unit that makes the light synthesized by the light synthesis unit incident on the spatial modulation element;
The video display device according to claim 1, comprising: The image display unit
A projection optical unit;
An image portion for displaying an image projected by the projection optical unit;
The video display device according to claim 1, comprising: The color break prediction unit, a luminance measurement unit that calculates contrast from the input video,
An edge detector that calculates edge strength from the input video;
The video display apparatus according to claim 1, further comprising a timing coefficient calculation unit that calculates the timing coefficient from the contrast and the edge intensity. The video display device according to claim 6, wherein the edge intensity is a maximum value of a difference in luminance from the periphery of the edge. The video display device according to claim 1, wherein the light source driving unit sets a light emission order, a light emission interval, and a light emission number of the monochromatic light source from the control coefficient. The video display device according to claim 1, wherein the spatial modulation element control unit sets a control order, a control interval, and a control count for each constituent color from the control coefficient.

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