JP4804498B2 - Image display device and image display method - Google Patents

Description

  The present invention relates to an image display method for displaying a stereoscopic image by alternately displaying a right-eye image and a left-eye image on a screen, and an image display apparatus capable of performing this method.

  A PTV (projection television) using a white lamp such as a discharge type xenon lamp, a metal halide lamp, or a halogen lamp as a light source and using a liquid crystal light valve or a DMD (digital micromirror device) as a spatial modulation means is known. In addition, in order to extend the life of a light source and expand the color reproduction range of an image, a PTV using a light emitting element such as a light emitting diode (LED) or a semiconductor laser (LD) as a light source is being realized (for example, Patent Documents). 1).

  In addition, there is known a stereoscopic video display device that alternately displays an image for the right eye and an image for the left eye on a display and observes the displayed image through shutter glasses (for example, see Patent Document 2).

JP 2007-65677 A (page 7, FIG. 1) JP-A-8-327961 (page 3)

  However, in order to display a stereoscopic image by the conventional image display device, when an image for the right eye and an image for the left eye are displayed alternately, the image for the right (or left) is displayed next. Since the left (or right) eye image cannot be correctly separated (a period corresponding to a period Tw in FIG. 4 to be described later), there is a problem that a stereoscopic image appears as a double image.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and the purpose of the present invention is to display a right-eye image and a left-eye image that are separated in time and displayed in a high quality manner. Another object of the present invention is to provide an image display device and an image display method that can display a stereoscopic image.

The image display apparatus according to the present invention includes a plurality of light emitting elements that emit light of different colors, a light source driving unit that drives the plurality of light emitting elements, and light emitted from the plurality of light emitting elements according to an input video signal. Image generation means for spatially modulating and projecting onto a screen; and timing control means for providing a timing signal indicating light emission periods of the plurality of light emitting elements to the light source driving means, wherein the timing control means comprises the input When the video signal is switched between a right eye signal and a left eye signal every 1/2 frame period, the timing signal for causing each light emitting element to emit light for a predetermined light emission period every 1/2 frame period is generated. a pulse light emission mode that has a constant light emission mode to emit the respective light emitting elements temporally constant intensity, both of the pulse light emission mode and the constant light emission mode It is characterized in that it is a possible choice.

In the image display method of the present invention, the step of supplying a timing signal indicating the light emission period of the plurality of light emitting elements from the timing control unit to the light source driving unit of the plurality of light emitting elements, and the light emitting elements of different colors And a step in which the image generating means spatially modulates the light emitted from the plurality of light emitting elements according to the input video signal and projects the light onto the screen. A pulse light emission mode for generating the timing signal for causing each light emitting element to emit light for a predetermined light emission period every 1/2 frame period when switching between a right eye signal and a left eye signal every two frame periods ; The method further comprises the step of selecting any one of a constant light emission mode in which each of the light emitting elements emits light with a constant intensity over time.

  According to the present invention, when the input video signal is switched to the signal for the right eye and the signal for the left eye every 1/2 frame period, the image for the right eye and the image for the left eye can be correctly separated and displayed. It is possible to obtain an effect that it is possible to display a high-quality stereoscopic image in which a double image does not appear.

Embodiment 1 FIG.
FIG. 1 is a block diagram schematically showing the configuration of an image display apparatus according to Embodiment 1 of the present invention (that is, an apparatus that performs the image display method according to Embodiment 1). As shown in FIG. 1, the image display apparatus according to the first embodiment includes a receiving unit 1 that receives video data D0 and a synchronization signal S0, and a red image frame memory (also referred to as “red frame memory”). 2R, a green image frame memory (also referred to as “green frame memory”) 2G, a blue image frame memory (also referred to as “blue frame memory”) 2B, and a red image liquid crystal light valve driving unit ( 3R, green image liquid crystal light valve drive unit (also referred to as “green light valve drive unit”) 3G, and blue image liquid crystal light valve drive unit (“blue light valve drive unit”) It is also referred to as a “light valve driving unit”.) 3B. The image display apparatus according to the first embodiment also includes a timing control unit 4 as a timing control unit that generates timing signals S2r, S2g, S2b and a timing signal 3, and a light emitting element driving unit (“LD” as a light source driving unit). 5).

  Furthermore, the image display device according to the first embodiment includes a red image liquid crystal light valve (also referred to as “red light valve”) 6R and a green image liquid crystal light valve (also referred to as “green light valve”). 6G, a liquid crystal light valve for blue image (also referred to as “blue light valve”) 6B, a red image LD (also referred to as “red LD”) 7R as a light emitting element, and a green image as a light emitting element LD (also referred to as “green LD”) 7G, LD for blue image (also referred to as “blue LD”) 7B as a light emitting element, lens 8R for red image, lens 8G for green image, blue The lens 8B for images, the dichroic lens 9 as a synthetic | combination means, the projection lens 10, and the screen 11 are provided. Each color light valve 6R, 6G, 6B, each color LD 7R, 7G, 7B, lens 8R, 8G, 8B, dichroic lens 9, and projection lens 10 constitute an image generating means for forming a color image on the screen 11. is doing. Further, instead of the red LD 7R, the green LD 7G, and the blue LD 7B, red LEDs, green LEDs, and blue LEDs, which are different types of light emitting elements, can be used.

  The receiving unit 1 receives video data D0 and a synchronization signal S0 from an external video device (not shown), outputs red video data D1r, green video data D1g, and blue video data D1b based on the video data D0, and A timing signal S1 based on the synchronization signal S0 is output.

  The red frame memory 2R temporarily stores red video data D1r from the receiving unit 1, the green frame memory 2G temporarily stores green video data D1g from the receiving unit 1, and the blue frame memory 2B receives The blue video data D1b from the unit 1 is temporarily stored. The red frame memory 2R sequentially reads out the temporarily stored red video data D1r for each line in synchronization with the timing signal S2r and outputs the read data to the red light valve driving unit 3R. The green frame memory 2G sequentially reads out the temporarily stored green video data D1g for each line in synchronization with the timing signal S2g, and outputs it to the green light valve driving unit 3G. The blue frame memory 2B sequentially reads out the blue video data D1b temporarily stored for each line in synchronization with the timing signal S2b, and outputs the read data to the blue light valve driving unit 3B.

  Based on the timing signal S1, the timing controller 4 outputs the timing signal S2r to the red frame memory 2R and the red light valve 6R, and outputs the timing signal S2g to the green frame memory 2G and the green light valve 6G. The timing signal S2b is output to the blue frame memory 2B and the blue light valve 6B. The timing control unit 4 outputs a timing signal S3 to the LD driving unit 5 based on the timing signal S1. In the first embodiment, the timing control unit 4 includes a constant light emission mode (described in detail in FIG. 2 to be described later) that is a drive mode for displaying a normal image, and a drive mode for displaying a stereoscopic image. And a pulse emission mode (described in detail in FIGS. 3 and 4 to be described later). The constant light emission mode is a driving mode in which the LDs 7R, 7G, and 7B of the respective colors emit light with a constant light emission intensity over time. In the pulse emission mode, when the input video signal is switched between the right eye signal and the left eye signal every ½ frame period, the LD7R, 7G, and 7B of each color is changed to a predetermined emission period every ½ frame period. This is a drive mode for generating a timing signal S3 for emitting light only.

  The red light valve driving unit 3R performs digital / analog conversion on the video data D1r sequentially input for each line, and sends it to the red light valve 6R as image data D2r. The green light valve driving unit 3G performs digital / analog conversion on the video data D1g sequentially input for each line, and sends the converted data to the green light valve 6G as image data D2g. The blue light valve driving unit 3B performs digital / analog conversion on the video data D1b sequentially input for each line, and sends it to the red light valve 6B as image data D2b.

  The LD drive unit 5 supplies drive currents Ir, Ig, and Ib to the red LD 7R, the green LD 7G, and the blue LD 7B in synchronization with the timing signal S3. The red LD 7R, the green LD 7G, and the blue LD 7B emit laser beams Lr0, Lg0, and Lb0 having intensities corresponding to the strengths of the driving currents Ir, Ig, and Ib during the period when the driving currents Ir, Ig, and Ib are supplied.

  The red light valve 6R spatially modulates the red laser light Lr0 according to the input image data D2r to generate red image light Lr1. The green light valve 6G spatially modulates the green laser light Lg0 according to the input image data D2g to generate green image light Lg1. The blue light valve 6B spatially modulates the blue laser light Lb0 according to the input image data D2b to generate blue image light Lb1. In the first embodiment, the case where each color light valve 6R, 6G, 6B is a transmissive liquid crystal light valve is described. However, each color light valve 6R, 6G, 6B is a reflective liquid crystal light valve. There may be. In the first embodiment, the case where a light valve is provided for each color has been described. However, it is also possible to use one DMD as the light valve.

  In each color light valve 6R, 6G, 6B, an image for one frame is formed based on the input image data D2r, D2g, D2b, and the amount of light transmitted through each pixel is determined according to the image data. The incident light is spatially modulated so that pixels with a large amount of transmitted light are bright and pixels with a small amount of transmitted light are displayed dark. The image light Lr1, Lg1, and Lb1 of each color generated by the red light valve 6R, the green light valve 6G, and the blue light valve 6B are combined by the dichroic lens 9 to become color image light L2, and the image light L2 is projected. The image is enlarged and projected on the screen 11 by the lens 10.

  2A to 2C show the display states of the light valves 6R, 6G, and 6B for each color and the LDs 7R, 7G, and 7B for each color when the image display apparatus according to the first embodiment displays a normal video. It is a figure which shows a light emission waveform (constant light emission mode). As shown in FIGS. 2A to 2C, the image data of each color is sequentially input to the light valves 6R, 6G, and 6B of each color in the frame period. The frame frequency is generally 60 Hz. However, the value of the frame frequency is not limited to 60 Hz. Further, the intensities Pcr, Pcg, and Pcb of the laser beams emitted from the LDs 7R, 7G, and 7B of the respective colors may be either the same value or different values. However, in the first embodiment, the intensities Pcr, Pcg, and Pcb of the laser beams emitted from the LDs 7R, 7G, and 7B are substantially constant over time.

  FIGS. 3A to 3C show the display states of the light valves 6R, 6G, and 6B for the respective colors and the light emission of the LDs 7R, 7G, and 7B for the respective colors when the image display apparatus according to the first embodiment displays a stereoscopic image. It is a figure which shows a waveform (pulse light emission mode). As shown in FIGS. 3A to 3C, in the first embodiment, the timing controller 5 switches the input video signal into a signal for the right eye and a signal for the left eye every ½ frame period. In other words, it has a pulse light emission mode for generating a timing signal for causing each light emitting element to emit light for a predetermined light emission period every ½ frame period.

  With the right-eye image data formed in the light valves 6R, 6G, and 6B of the respective colors, the LDs 7R, 7G, and 7B of the respective colors are caused to emit light in a pulse shape, so that the image for the right eye is also emitted on the screen 11. Is displayed at the same time. Next, with the left-eye image data formed in the light valves 6R, 6G, and 6B of the respective colors, the LDs 7R, 7G, and 7B of the respective colors are caused to emit light in a pulse shape, and thus the image for the left eye is also displayed on the screen 11. Will be displayed for the same time as the light emission period. In this way, a right-eye image and a left-eye image are alternately displayed on the screen 11, and the displayed image is viewed through the shutter glasses, so that a stereoscopic image can be viewed.

  4 (a) and 4 (b) are enlarged views of the ½ frame period of FIGS. 3 (a) to 3 (c). FIG. 4 (a) shows each color when displaying a stereoscopic video. The display state of the light valve 6R (or 6G or 6B) is shown, and FIG. 5B shows the light emission waveform (pulse emission mode) of the LD 7R (or 7G or 7B) of each color when displaying a stereoscopic image.

  The predetermined light emission period (period Td in FIGS. 4A and 4B) in the pulse light emission mode of the image display device according to Embodiment 1 is 1 based on the input video signal to the light valve 6R (or 6G or 6B). The period from the first time point t1 when the writing of the screen image data D2r (or D2g or D2b) is completed to the second time point t2 when the writing of the image data of the next one screen of the image data of one screen is started. This is the period within Ta. In the first embodiment, the predetermined pulse emission period Td in the pulse emission mode is a period Td from the third time point t3 when the predetermined transition time Tm has elapsed from the first time point t1 to the second time point t2. is there. However, the predetermined pulse emission period in the pulse emission mode is shorter than the period from the third time point t3 to the second time point t2 within the period from the third time point t3 to the second time point t2. May be. As described above, the right-eye image data and the left-eye image data are alternately formed in the light valves 6R, 6G, and 6B of the respective colors every ½ frame period. The waveforms of the laser beams emitted from the LDs 7R, 7G, and 7B of the respective colors are pulse emission waveforms that are repeated every ½ frame period synchronized with the image data.

  In general, the image data is sequentially written for each line in the light valves 6R, 6G, and 6B of each color, so that writing time Tw is required to write the image data for one screen. Further, each pixel of each color light valve 6R, 6G, 6B requires a transition time Tm from the time image data is written until the pixel state is stabilized. As a result, the period in which the image is stable in the ½ frame period is a period Td obtained by subtracting the writing time Tw and the transition time Tm from the ½ frame period.

  As described above, the LDs 7R, 7G, and 7B of the respective colors are caused to emit the pulse only during the period Td in which the images formed on the light valves 6R, 6G, and 6B of the respective colors are stable, so that the ½ frame period is obtained. An image completely separated for each time can be displayed on the screen 11. Further, the LD7R, 7G, and 7B are pulse-emitted only during a period when the right-eye image and the left-eye image formed on the light valves 6R, 6G, and 6B of the respective colors are stable, The image for the left eye can be displayed on the screen 11 as an image that is correctly separated every ½ frame period.

  By the way, when the LDs 7R, 7G, and 7B of the respective colors are caused to emit light in a pulsed manner, the light emission time is shortened, so that the brightness of the image displayed on the screen 11 is lowered as compared with the case where the light is constantly emitted. For this reason, when LD7R, 7G, and 7B of each color is pulse-emitted, the image displayed on the screen 11 becomes dark by increasing the peak emission intensity Ppr, Ppg, and Ppb of LD7R, 7G, and 7B of each color. Can be prevented. Unlike a lamp light source, light emitting elements such as LD and LED can easily adjust the peak light emission intensity when pulse light is emitted, and the light emission intensity can be easily increased by increasing the pulse drive current. . Even when pulsed light is emitted in this way, it is possible to prevent the image displayed on the screen 11 from becoming dark by increasing the peak light emission intensity of the light emitting element.

  According to the image display device according to the first embodiment, the light source driving unit is provided with a mode in which the light emitting element emits light at a constant rate and a mode in which pulse light emission is performed, and the two modes are switched depending on the video signal (for example, In addition to displaying normal video, stereoscopic video can also be displayed by automatic switching based on the difference in frame frequency or switching by user operation. In addition, when displaying a stereoscopic video, the right-eye image and the left-eye image can be correctly separated and displayed in time, so that a double video does not appear and the quality of the stereoscopic image can be improved.

  Further, according to the image display device according to the first embodiment, since the light emitting element is used as the light source, it is easy to increase the peak light emission intensity in the pulse light emission mode, and the image is displayed so as not to become dark. be able to.

  Furthermore, according to the image display apparatus according to the first embodiment, since the light valves 6R, 6G, and 6B are provided corresponding to the LDs 7R, 7G, and 7B of the respective colors, there is an effect that the display image is hardly colored. .

  Furthermore, in the image display device according to the first embodiment, when the LDs 7R, 7G, and 7B of the respective colors are subjected to pulse light emission for a period shorter than the period Td, there is an effect that blurring of moving images is improved.

Embodiment 2. FIG.
FIGS. 5A and 5B are diagrams showing the emission intensity of LD of each color in the image display apparatus according to the second embodiment of the present invention (that is, the apparatus that performs the image display method according to the second embodiment). (A) shows a constant emission mode, and (b) shows a pulse emission mode. FIG. 5A shows the light emission intensity Pc when the LD7R (or 7G or 7B) of each color is caused to emit constant light, and FIG. 5B shows the pulse of the LD7R (or 7G or 7B) of each color. The peak emission intensity Pp and the emission period Th are shown.

In the second embodiment, the area of the hatched portion in the ½ frame period T in the constant emission mode shown in FIG. 5A and the ½ frame period in the pulse emission mode shown in FIG. The LDs 7R, 7G, and 7B of the respective colors are driven so that the areas of the hatched portions in T are equal. The constant light emission intensity in the constant light emission mode shown in FIG. 5A is Pc (watt), the repetition time (1/2 frame period) is T (seconds), and the peak in the pulse light emission mode shown in FIG. When the emission intensity is Pp (watt) and the pulse width in the 1/2 frame period is Th (seconds), the following formula is given: Pc × T = Pp × Th
The light emission intensities Pc and Pp and the light emission time Th are set so as to satisfy the above.
If this equation is transformed,
Pc = Pp × Th / T
It becomes. This expression means that the light emission intensities Pc and Pp and the light emission time Th are set so that the time averages of the light emission intensity Pc in the constant light emission mode and the light emission intensity Pp in the pulse light emission mode are equal. Further, the pulse width Th in the pulse emission mode is set to a value equal to the period Td described in FIGS. 4A and 4B, or to a period shorter than the period Td within the period Td. There is.

  The brightness of the image displayed on the screen 11 is proportional to the average of the emission intensity of the LD 7R (or 7G or 7B) of each color. By making the light emission intensity in the constant light emission mode equal to the time average value of the light emission intensity in the pulse light emission mode, the brightness of the image when displaying the stereoscopic image is almost the same as the brightness of the image when displaying the normal image. Can be the same. In the present invention, when the time average value of the light emission intensity in the pulse light emission mode and the light emission intensity value in the constant light emission mode are made equal, both values are almost equal in addition to the case where both values are exactly equal. Includes cases where they are equivalent.

  In the second embodiment, the points other than the above are the same as those in the first embodiment.

1 is a block diagram schematically showing a configuration of an image display device according to a first embodiment of the present invention (that is, a device that performs an image display method according to the first embodiment). (A) thru | or (c) are the figures which show the display state of the light valve of each color when the image display apparatus which concerns on Embodiment 1 displays a normal image, and the light emission waveform (constant light emission mode) of LD of each color. is there. (A) thru | or (c) is a figure which shows the display state of the light valve of each color at the time of displaying the stereo image of the image display apparatus which concerns on Embodiment 1, and the light emission waveform (pulse light emission mode) of LD of each color. . (A) And (b) is a figure which expands and shows the 1/2 frame period of Fig.3 (a) thru | or (c), (a) shows the display state of the liquid crystal light valve in a stereoscopic video display mode. (B) shows the light emission waveform (pulse light emission mode) of the LD. (A) And (b) is a figure which shows the emitted light intensity of LD in the image display apparatus (namely, apparatus which implements the image display method concerning Embodiment 2) concerning Embodiment 2 of this invention, ( a) shows a constant emission mode, and (b) shows a pulse emission mode.

Explanation of symbols

1 receiver, 2R frame memory for red image (frame memory for red), 2G frame memory for green image (frame memory for green), 2B frame memory for blue image (frame memory for blue, 3R liquid crystal light valve drive for red image) (Light valve driving unit for red), 3G liquid crystal light valve driving unit for green image (green light valve driving unit), 3B liquid crystal light valve driving unit for blue image (blue light valve driving unit), 4 timing control unit 5 Light-emitting element drive unit (LD drive unit), 6R Liquid crystal light valve for red image (light valve for red), 6G Liquid crystal light valve for green image (light valve for green), 6B Liquid crystal light valve for blue image (for blue) Light valve), 7R Red image LD (Red LD), 7G Green image LD (Green LD), 7B Blue image LD Blue LD), a lens for 8R red image, a lens for 8G green image, a lens for 8B blue image, 9 dichroic cleanse, 10 projection lens, 11 screen.

Claims (10)

A plurality of light emitting elements that emit light of different colors;
Light source driving means for driving the plurality of light emitting elements;
Image generation means for spatially modulating light emitted from the plurality of light emitting elements according to an input video signal and projecting the light onto a screen;
Timing control means for providing a timing signal indicating a light emission period of the plurality of light emitting elements to the light source driving means,
The timing control means includes
When the input video signal is switched to a right eye signal and a left eye signal every 1/2 frame period, the timing signal for causing each light emitting element to emit light for a predetermined light emission period every 1/2 frame period And a constant light emission mode in which each light emitting element emits light with a constant intensity over time,
One of the pulse light emission mode and the constant light emission mode can be selected .   The image display apparatus according to claim 1, wherein the image generation unit includes a light valve that spatially modulates light emitted from the plurality of light emitting elements according to the input video signal. The light bulb is provided for each light emitting element,
The image display device according to claim 2, wherein the image generating unit includes a combining unit that combines the spatially modulated light generated by each of the light valves.   The predetermined light emission period in the pulse light emission mode is a period of the next one screen of the one screen image data from the first time point when the writing of the one screen image data based on the input video signal to the light valve is completed. The image display apparatus according to claim 2, wherein the image display apparatus is a period within a period up to a second time point at which image data writing is started.   The predetermined pulse emission period in the pulse emission mode is a period within a period from a third time point at which a predetermined transition time has elapsed from the first time point to the second time point. The image display device according to claim 4. The light source driving means drives the light emitting element so that a time average value of light emission intensity of the light emitting element in the pulse light emission mode is equal to a value of light emission intensity of the light emitting element in the constant light emission mode. The image display device according to claim 1 , wherein the image display device is a display device. Providing a timing signal indicating a light emission period of the plurality of light emitting elements from the timing control unit to the light source driving unit of the plurality of light emitting elements;
The plurality of light emitting elements emitting light of different colors;
Image generating means spatially modulates the light emitted from the plurality of light emitting elements according to an input video signal and projects the light onto a screen;
When the input video signal is switched to a right eye signal and a left eye signal every 1/2 frame period, the timing signal for causing each light emitting element to emit light for a predetermined light emission period every 1/2 frame period The method further comprises the step of selecting one of a pulse light emission mode for generating light and a constant light emission mode for causing each of the light emitting elements to emit light at a constant intensity over time . The predetermined light emission period in the pulse light emission mode is the next of the image data of the one screen from the first time point when the writing of the image data of one screen based on the input video signal to the light valve of the image generating means is completed. The image display method according to claim 7 , wherein the image display period is a period within a period up to a second time point when writing of image data of one screen is started. The predetermined pulse emission period in the pulse emission mode is a period within a period from a third time point at which a predetermined transition time has elapsed from the first time point to the second time point. The image display method according to claim 8 . In the step of emitting light of different colors by the plurality of light emitting elements, the time average value of the light emission intensity of each light emitting element in the pulse light emission mode is equal to the value of the light emission intensity of each light emitting element in the constant light emission mode. The image display method according to claim 7 , wherein each of the light emitting elements is driven.

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