JP2001264660A - Video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a video display device with little power consumption capable of the high definition video display excellent in the display performance of a low gradation area of a video by prolonging service life of a light source and improving the optical use efficiency. SOLUTION: A plurality of a red, a green and a blue LEDs are arranged in a line in a vertical direction, and LED arrays 31R, 31G and 31B of each color are constituted. A video signal is transformed into video signal data grouped in a line of the vertical direction of a video by using a video signal processing circuit 17 and image memories 32R, 32G and 32B, etc., pulse duration modulation of it is performed in the pulse duration modulation circuits 33R, 33G and 33B of each color, the LED arrays 31R, 31G and 31B of each color are driven with fixed electric current, and a line of video is displayed simultaneously in the vertical direction. A horizontal scanning reflecting mirror 15 is stopped in a period displaying the video of a column of the one group and it displays as the video on a screen by scanning to a shape of a step which moves when moving to the display of the video of the following column group horizontally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device for displaying an image by projecting light modulated and emitted from a light source onto a screen.

[0002]

2. Description of the Related Art In recent years, with the development of video equipment such as video tape recorders and video disk players and video software, there has been an increasing demand for large-screen video display devices for enjoying powerful videos. As a conventional large-screen image display device, there is an image display device that uses a liquid crystal panel for an image display unit, spatially modulates light emitted from a light source with the liquid crystal panel, and projects an image on a screen or the like.

FIG. 12 is a block diagram showing an example of a conventional video display device using a liquid crystal panel for a video display unit.

In FIG. 12, a lamp 101 as a light source is shown.
And the reflected light reflected by the reflecting mirror 102 are collected by a condenser lens 103, and then red R, green G,
The light is decomposed into blue B primary color lights. Each primary color light is guided to a red liquid crystal panel 112, a green liquid crystal panel 113, and a blue liquid crystal panel 114, combined by a color combining prism 115, and then projected onto a screen 11 by a projection lens 116.
7 is projected. Further, total reflection mirrors 106 and 10
7, 108 are for changing the optical path of the light beam,
The lenses 109, 110, 111 are connected to the respective liquid crystal panels 112,
This is for adjusting the angles of the light beams incident on the light sources 113 and 114. As the lamp 101 as a light source, a white light source such as a discharge type ultra-high pressure mercury lamp, a metal halide lamp, or a thermoluminescent halogen lamp is used.

The red liquid crystal panel 112, the green liquid crystal panel 113, and the blue liquid crystal panel 114 are driven by a red video signal, a green video signal, and a blue video signal, respectively. The light is spatially modulated when passing through the liquid crystal panels 112, 113, and 114, and is projected by the projection lens 116 onto the screen 117.
Projected on top as a video.

[0006]

As described above, in the conventional video display device as described above, each color liquid crystal panel is driven by each color video signal, and the light transmittance by each color liquid crystal panel is changed. Image is spatially modulated, but because the light blocking performance of each color liquid crystal panel is not perfect, it is difficult to obtain low-gradation video display performance, high contrast, and high-quality video. There were challenges.

Further, in the above-mentioned conventional image display device, a lamp such as an ultra-high pressure mercury lamp or a metal halide lamp is used as a light source. However, the lamp generally changes greatly with time and has a short life. Therefore, there was a problem that the replacement had to be performed in thousands of hours.

Further, most of the currently used lamps have a low light utilization efficiency, which is a ratio of emitted light to input power, so that a bright lamp must be used in order to obtain a bright projected image. Power increases,
There was a problem that the heat generated from the lamp also increased.

[0009]

According to the present invention, there is provided an image display apparatus comprising: a pulse width modulation means for pulse width modulating an electric image signal in accordance with information of an image to be displayed; Each of red, green, and blue light emitting means for emitting light in a pulsed manner in red, green, and blue by an output signal from the modulating means, and the red, green,
Light beam scanning means for scanning the light emitted by each color light emitting means for blue in the horizontal and vertical directions spatially, and the light emitted by each color light emitting means for red, green, and blue on a screen. An image forming unit for forming an image, the light beam scanning unit scans in a horizontal direction and a vertical direction so as to synchronize with the horizontal scanning and the vertical scanning of the input electric video signal, and causes each color light emitting unit to emit light. In the period, an image is displayed on the screen by controlling the scanning of the light beam scanning means to stop.

The image display apparatus of the present invention further comprises a pulse width modulation means for pulse width modulating an electric image signal in accordance with information of an image to be displayed, and a red, green, and green signal, respectively, according to an output signal from the pulse width modulation means. For red, a plurality of light-emitting elements that emit light in a pulsed manner in blue are arranged in a row for each color.
Light emitting means for each color for green and blue, light beam scanning means for scanning light emitted by each of the light emitting means for red, green and blue, and light emitting means for each color for red, green and blue Image forming means for forming an image on the screen of the light emitted by the plurality of light-emitting elements in the horizontal or vertical direction of an image based on the input electric image signal. Light emitted from the red, green, and blue light emitting units by the light beam scanning unit in a direction orthogonal to the direction in which the light emitting elements of the respective color light emitting units for green, blue, and blue are projected in a line. Scanning, and controlling the light scanning unit to stop scanning during the period in which each color light emitting unit emits light, thereby displaying an image on the screen. It is.

According to the present invention, the intensity of light in a low gradation region is sufficiently reduced by using a self-luminous element which emits light by itself as a modulating means for converting an electric image signal into a change in intensity of light. Therefore, the display performance in the low gradation region can be improved, and the display quality can be improved with high contrast. In addition, the light source has a long service life and low power consumption, and furthermore, the simplified optical system can provide a small-sized image display device.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image display apparatus according to the present invention comprises a pulse width modulation means for pulse width modulating an electric image signal in accordance with information of an image to be displayed, and an output signal from the pulse width modulation means. Red, green, and blue light emitting units that emit light in pulses in green and blue, and the light emitted by the red, green, and blue light emitting units are spatially and horizontally and vertically. Light scanning means for scanning in the directions, and image forming means for forming the light emitted by the red, green and blue light emitting means on a screen, and the horizontal scanning of the input electric video signal And scanning the light beam scanning means in the horizontal direction and the vertical direction so as to synchronize with the vertical scanning, and controlling the light beam scanning means to stop scanning during the period in which each color light emitting means emits light. And displaying an image on the screen by using a self-luminous element that emits light by itself as a modulating unit that converts an electric image signal into a change in light intensity. Can be sufficiently weakened, so that the display performance in a low gradation region can be improved, and further, the display quality can be improved with high contrast. In addition, the light source has a long life and power consumption can be reduced, and further, the device can be downsized by simplifying the optical system.

The image display apparatus of the present invention further comprises a pulse width modulation means for pulse width modulating an electric image signal in accordance with information of an image to be displayed; For red, a plurality of light-emitting elements that emit light in a pulsed manner in blue are arranged in a row for each color.
Light emitting means for each color for green and blue, light beam scanning means for scanning light emitted by each of the light emitting means for red, green and blue, and light emitting means for each color for red, green and blue Image forming means for forming an image on the screen of the light emitted by the plurality of light-emitting elements in the horizontal or vertical direction of an image based on the input electric image signal. Light emitted from the red, green, and blue light emitting units by the light beam scanning unit in a direction orthogonal to the direction in which the light emitting elements of the respective color light emitting units for green, blue, and blue are projected in a line. Scanning, and controlling the light scanning unit to stop scanning during the period in which each color light emitting unit emits light, thereby displaying an image on the screen. By using a self-luminous element that emits light by itself as a modulation unit that converts an electric image signal into a change in light intensity, the light intensity in a low gradation region can be sufficiently reduced. The display performance in the low gradation region can be improved, and the display quality can be improved with high contrast. In addition, the light source has a long life and power consumption can be reduced, and further, the device can be downsized by simplifying the optical system.

The first embodiment of the first invention will be described below with reference to FIGS. 1 to 4, and the second to fourth embodiments of the second invention will be described with reference to FIGS.

(Embodiment 1) FIG. 1 is a block diagram of an image display device according to Embodiment 1 of the first invention,
Is a red light emitting diode as a red light emitting means, 11G is a green light emitting diode as a green light emitting means, 11B is a blue light emitting diode as a blue light emitting means, and 12 is a light beam emitted from each of the light emitting diodes 11R, 11G and 11B. Lens 13 for condensing the light and forming an image, 13 is a projection lens for projecting the image formed by the light collecting lens 12, 14
Is a vertical scanning reflector for scanning in the vertical direction while reflecting light rays from the projection lens 13, 15 is a horizontal scanning reflector for scanning in the horizontal direction while also reflecting light rays, and 16 is a screen. . Hereinafter, the light emitting diode is referred to as an LED.

FIG. 2 is a block diagram for controlling the operation of the video display device shown in FIG. 1. Reference numeral 17 denotes a device for separating or adjusting an input electric video signal A (hereinafter, simply referred to as a video signal) into respective primary color signals. Signal processing circuit for separating the horizontal synchronizing signal H and the vertical synchronizing signal V from the video signal A, and 21R, 21G, and 21B for red processed by the video signal processing circuit 17, respectively. A pulse width modulation circuit for red, a pulse width modulation circuit for green, a pulse width modulation circuit for blue, and 22R, 22G, for pulse width modulation of a video signal, a video signal for green, and a video signal for blue in accordance with gradation.
22B is a pulse width modulation circuit for each color 21R, 21G,
Red LED by video signal for each color processed by 21B
A red LED driving circuit, a green LED driving circuit, and a blue LED driving circuit for driving the 11R, the green LED 11G, and the blue LED 11B, and an image position control circuit 23, which is a horizontal synchronizing signal from the synchronizing signal separating circuit 18. The signal H and the vertical synchronizing signal V are used to detect the position of the image indicated by the video signal A currently input, and to control the pulse width modulation circuits 21R, 21G, 21B for each color, the vertical scanning reflector control circuit 24, and the horizontal direction. A control signal for controlling the operation of the scanning mirror control circuit 25 is generated. The vertical scanning reflector control circuit 24 controls the operation of the vertical scanning reflector 14 in accordance with a control signal from the image position control circuit 23. The horizontal scanning reflector control circuit 25 controls the operation of the horizontal scanning reflector 15 in the same manner.

The operation of the video display apparatus according to the first embodiment of the present invention will be described below with reference to FIGS.

First, the video signal A input in FIG.
Are adjusted by a video signal processing circuit 17 and separated into respective primary color signals.
R is input to the green pulse width modulation circuit 21G and the blue pulse width modulation circuit 21B. Further, the input video signal A is separated into a horizontal synchronizing signal H and a vertical synchronizing signal V by a synchronizing signal separating circuit 18 and input to an image position signal control circuit 23. Then, the image position control circuit 23 outputs the horizontal synchronization signal H
And the vertical synchronizing signal V to detect the position of the currently input video signal on the screen and generate a control signal indicating the position of the image.
Output to 4,25.

The pulse width modulation circuits for each color 21R, 21G,
Reference numeral 21B denotes a control signal from the image position control circuit 23, which converts a video signal for one pixel of the input video signal into a signal by performing pulse width modulation in accordance with the signal level, and converts the signal into a LED drive circuit 22R for each color. Input to 22G and 22B.

The red LED driving circuit 22R operates in accordance with the pulse signal of the input red video signal.
Is turned on / off to drive so as to emit light in pulses. Similarly, the green LED drive circuit 21G and the blue LED drive circuit 21B are also a green LED 11G and a blue LED.
The light emission of 11B is driven in a pulse shape. Here, L for each color
The ED driving circuits 22R, 22G, and 22B are provided for the respective color LEDs 11
Each LED is used when R, 11G and 11B emit light.
It is driven so that a constant amount of current flows every time. Generally LED
Although the current-brightness characteristics of LED are not linear,
When the LED is driven by pulse width modulation by supplying a constant current to the LED, the brightness when the LED emits light can be made constant, so that it is possible to adjust the LED so as to eliminate variations in brightness.

Next, in FIG. 1, the light beams emitted from the red LED 11R, the green LED 11G, and the blue LED 11B are condensed by the condensing lens 12 and once formed into an image. The image formed by the condenser lens 12 is projected on the screen 16 by the projection lens 13, but since the LEDs 11R, 11G, and 11B, which are light-emitting sources, emit light at one point, they are still dotted on the screen 16. Is displayed.

The horizontal scanning reflecting mirror 15 is controlled by a horizontal scanning reflecting mirror control circuit 25 (FIG. 2) so that the angle of the reflecting mirror is changed. The optical path is scanned in the horizontal direction. The operation of the horizontal scanning reflecting mirror 15 is controlled so as to stop during the period when each color LED is displaying one pixel, and to move to the next position during the period until the display of the next pixel starts. The vertical scanning reflecting mirror 14 is controlled by a vertical scanning reflecting mirror control circuit 24 (FIG. 2) so that the angle of the reflecting mirror changes, and each L is synchronized with the vertical scanning of the video signal.
The optical path from the ED is scanned in the vertical direction. The operation of the vertical scanning reflecting mirror 14 is controlled so that it stops during one horizontal scanning period of the video signal and moves to the next position during the period until the next horizontal scanning starts.

The red LED 11R, the green LED 11G, and the blue LED 11B are applied to the video signal subjected to the pulse width modulation as described above.
Is driven, and the emitted light is scanned in the vertical direction and the horizontal direction by the vertical scanning reflector 14 and the horizontal scanning reflector 15, respectively, so that the projected image displayed in the form of dots on the screen 16 is displayed. Since the image can be displayed in a plane, it can be displayed as an image on the screen 16.

Here, the vertical scanning reflecting mirror 14 and the horizontal scanning reflecting mirror 15 can be easily constituted by a movable reflecting mirror such as a galvano mirror or a polygon mirror using a stepping motor. Further, it is clear that the means for changing the optical path of the light beam is not limited to using a reflecting mirror, but may use a prism or the like.

FIG. 3 is a state diagram for explaining the relationship between the light emitting state of the LED and the operating time of the scanning reflector. As an example, the light emitting state of the LED and the temporal operation of the horizontal scanning reflecting mirror 15 are shown. ing.

The light emitting state of each LED and the operation of the horizontal scanning reflecting mirror 15 will be described again with reference to FIG.

In FIG. 3, (1) shows the light emitting state of the LED, (2) shows the operation of moving and stopping the horizontal scanning reflector 15, and (3) shows the horizontal pixel N in the time axis direction T. Thus, the pixels displayed in accordance with the horizontal scanning of the video signal temporally sequentially move from the pixel N-1 to the pixel N + 5. The horizontal scanning reflector 15 is moved and positioned by the horizontal scanning reflector control circuit 25 at the timing when the displayed pixel moves from the next pixel, for example, the pixel N-1 to the pixel N. It is controlled to perform an operation of stopping during the display period of the subsequent pixel N.

Each LED is an LED driving circuit 2 for each color.
2R, 22G, 22B, horizontal scanning reflector 1
5 emits light by the pulse width modulated drive signal during the stop period (the hatched portion in (1) of FIG. 3).
Then, while the horizontal scanning reflecting mirror 15 is moving, it is driven so as not to emit light.

As described above, in the image display device, the LED
While the horizontal scanning reflecting mirror 15 is stopped while the horizontal scanning reflecting mirror 15 is moved, the LED is stopped while the horizontal scanning reflecting mirror 15 is moved.
LED is driven so as not to emit light
Is emitted from the screen 1 during the display period of the pixel N.
6, which is a side effect of displaying a video signal with pulse width modulation, such as when a video with subtle changes in brightness moves, contour lines can be seen there. The so-called pseudo contour phenomenon does not occur.

The vertical scanning reflecting mirror 14 is similarly stopped by the vertical scanning reflecting mirror control circuit 24 during one horizontal scanning period of the video signal, and the next horizontal scanning is started until the next horizontal scanning starts. It is controlled to perform the operation of moving to the display position.

FIG. 4 is a view showing a display state of an image on the screen 16 of FIG. As shown in FIG. 4, the light rays from each LED are projected by the projection lens 13 at one place on the screen 16. Scanning is performed in the horizontal direction by the horizontal scanning reflector 15 in synchronization with the horizontal scanning of the video signal, and is scanned in the vertical direction by the vertical scanning reflector 14 in synchronization with the vertical scanning of the video signal. Displayed as video.

As a conventional example which seems to be similar to the first embodiment, there is an example shown in a video projector of Japanese Patent Application Laid-Open No. Hei 7-151995. Each color LED 11R, 11 of the first embodiment
G, 11B, a light emitting part corresponding to the condenser lens 12, a projection lens 13, a light incident part corresponding to the vertical scanning reflecting mirror 14, and a horizontal scanning reflecting mirror 15, and both parts are optical transmission parts. The image display device according to the first embodiment is described in Japanese Unexamined Patent Application Publication No. 7-151, whereas it is intended to increase the degree of freedom of installation of the light emitting portion and the light incident portion by being configured to be connected.
In the image projection device disclosed in Japanese Patent Application Laid-Open No. 995/995, the light emitting portion and the light incident portion are so configured as to be in close contact with each other. It is a completely different purpose.

As described above, in the image display device of the first embodiment, the light emitting diode is used as the light source, the driving of the light emitting diode itself is performed by a signal obtained by modulating the image signal with the pulse width, and the operation of the scanning optical system is performed by the light emitting diode. Is configured to be stationary during the light emission period, so that adjustments can be made to eliminate variations in the brightness of individual light emitting diodes, and the light emission amount of the light emitting diodes themselves is sufficient in the low gradation region. By lowering the display quality, the display performance in the low gradation region can be improved, and the display quality can be improved with high contrast.

Also, by using a light emitting diode as the light source, the life of the light source can be extended. Further, since the light emitting diode consumes less power than the conventionally used lamp, the power consumption of the image display device can be reduced. Furthermore, compared to a video display device using a liquid crystal panel, the optical system of the device is simpler, and a great effect that the device can be downsized can be obtained.

In the first embodiment, the case where the light emitting diode is used as the light emitting means has been described. However, an electroluminescent element or a semiconductor laser element may be used instead of the light emitting diode.

(Embodiment 2) FIG. 5 is a configuration diagram of a video display apparatus according to Embodiment 2 of the second invention. In addition,
The same components as those in the first embodiment (FIG. 1) of the first invention are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 5, 31R is a red light emitting diode array in which a plurality of red light emitting diodes as red light emitting means are vertically arranged in a line, and 31G is a plurality of green light emitting diodes as green light emitting means arranged in a vertical direction. A green light emitting diode array arranged in a line, 31B is a blue light emitting diode array in which a plurality of blue light emitting diodes as blue light emitting means are arranged in a vertical line, and 12 is irradiated from each of the light emitting diode arrays 31R, 31G, 31B. A condensing lens for converging light rays to form an image, 1
Reference numeral 5 denotes a horizontal scanning reflector for scanning in the horizontal direction while reflecting light rays from the condenser lens 12, and 16 denotes a screen.

FIG. 6 is a block diagram for controlling the operation of the video display device shown in FIG. 5. Blocks having the same functions as those in the block diagram of the first embodiment (FIG. 2) are denoted by the same reference numerals.
The description is omitted. Here, 32R, 32G, 32B
Are image memories for each color for storing the video signal from the video signal processing circuit 17 and for converting the timing of the video signal so as to be suitable for scanning by the horizontal scanning reflector 15, 33R, 33G and 33B are each Pulse width modulation circuits 34R, 3 for pulse width modulation of video signals from the image memories 32R, 32G, 32B for respective colors in accordance with gradations;
4G and 34B are pulse width modulation circuits 33R and 3 for each color, respectively.
An LED driving circuit for each color for driving each color LED array 31R, 31G, 31B by a video signal for each color processed by 3G, 33B, an image position control circuit 35, and a horizontal synchronizing signal H from the synchronizing separation circuit 18 And the vertical synchronizing signal V to detect the position of the image indicated by the currently input video signal A.
R, 33G, 33B and horizontal scanning reflector control circuit 25
Generates a control signal for controlling the operation of. The horizontal scanning position control circuit 25 controls the operation of the horizontal scanning mirror 15 according to a control signal from the image position control circuit 35.

The operation of the video display apparatus according to the second embodiment of the present invention will be described below with reference to FIGS.

First, in FIG. 6, an input video signal A is subjected to signal adjustment and separation into primary color signals in a video signal processing circuit 17, and a red image memory 32R, a green image memory 32G, and a blue image memory 32G, respectively. To the image memory for use 32B. In each of the image memories 32R, 32G, and 32B, a video signal for one screen is recorded by a control signal from the image position control circuit 35, and then the video signal data for each column is obtained by grouping the signals in one column in the vertical direction of the screen. Convert.

The image position control circuit 35 detects the current position on the screen of the video signal A input from the horizontal synchronizing signal H and the vertical synchronizing signal V, and generates a control signal indicating the position of the image. Each color pulse width modulation circuit 33R, 33G, 33
B performs pulse width modulation according to the signal level for each pixel of the video signal for each column input from the image memory for each color 32R, 32G, 32B by the control signal from the image position control circuit 35. Red LED drive circuit 34
R drives the red LED array 31R to emit light in a pulsed manner by turning on / off the light emission of the red LED array 31R according to the video signal data pulse width modulated by the red image memory 32R and the red pulse width modulation circuit 33R. The red LED array 31R is formed by arranging a plurality of LEDs in a line in a direction corresponding to the vertical direction of the screen, and an image corresponding to one line in the vertical direction of an image is displayed at the same time.

Similarly, the green LED drive circuit 34G and the blue LED drive circuit 34B drive the green LED array 31G and the blue LED array 31B, and simultaneously display an image corresponding to one column in the vertical direction of the image.

Here, each color LED drive circuit 34R, 3R
4G and 34B, as described in the first embodiment, the LED arrays 31R, 31G, and 31B of each color are driven by pulse width modulation by supplying a constant current to each LED, so that LE
Adjustments can be made to eliminate variations in brightness for each D.

Next, referring to FIG.
The light beams emitted from R, 31G, and 31B are condensed by the condenser lens 12 and formed into a small image, and then displayed on the screen 16 as a single line of video in the vertical direction. At this time, the horizontal scanning reflecting mirror 15 is controlled by the horizontal scanning reflecting mirror control circuit 25 to change the angle of the reflecting mirror, and operates so as to scan the optical path from each LED in the horizontal direction. By performing the scanning in the horizontal direction in synchronization with the horizontal scanning of the video signal, the one row of images projected on the screen 16 in the vertical direction can be scanned in the horizontal direction and displayed as an image.

Here, the scanning of the horizontal scanning reflecting mirror 15 is stopped during the period in which the LED arrays of each color are displaying a row of images, as in the case of FIG. 3 of the first embodiment.
The operation is controlled so as to move to the next position until the display of the video of the next column starts. LED array 31 for each color
R, 31G, and 31B are also driven so as not to emit light while the horizontal scanning reflector 15 moves, as described with reference to FIG. 3 of the first embodiment.

By driving the red LED array 31R, the green LED array 31G, and the blue LED array 31B with the video signal having the pulse width modulated as described above, the emitted light is scanned by the horizontal scanning reflector 15 in the horizontal direction. An image can be projected and displayed on the screen 16.

Here, the horizontal scanning reflecting mirror 15 can be easily constituted by a movable reflecting mirror such as a galvano mirror or a polygon mirror using a stepping motor. Further, it is clear that the means for changing the optical path of the light beam is not limited to using a reflecting mirror, but may use a prism or the like.

FIG. 7 is a diagram showing a display state of an image on the screen 16. In FIG. 7, for easy understanding, 1
The display state by the color LED array is shown. As shown in FIG. 7, the light from each LED array is
6 are projected in a row in the vertical direction, and are scanned in the horizontal direction by a horizontal scanning reflector 15 which is scanned in synchronization with the horizontal scanning of the video signal, and displayed as an image.

(Embodiment 3) FIG. 8 is a configuration diagram of a video display apparatus according to Embodiment 3 of the second invention. In the image display apparatus shown in FIG. 5 according to the second embodiment, a projection lens 13 is provided between a condenser lens 12 and a horizontal scanning reflector 15 in the third embodiment,
The image of each of the LED arrays 31R, 31G, and 31B formed in step 2 is projected on the screen 16. With the structure as in the image display device described in Embodiment 3, even when the light beam emitted from the light source is emitted at a spread angle, the light can be collected by the projection lens 13 without loss. A bright projected image can be displayed on the screen, and the screen size can be set arbitrarily.

As described above, in the video display devices of the second and third embodiments described above, the light emitting diode is used as the light source, and the driving of the light emitting diode itself is performed by a signal obtained by modulating the video signal with the pulse width, and the scanning optical system is used. The above operation is configured to be stationary during the period when the light emitting diode emits light, so that it can be adjusted so as to eliminate variations in the brightness of each light emitting diode. Since the light emission amount itself is sufficiently low, the display performance in a low gradation region can be improved, so that the display quality can be improved with high contrast.

Further, by using a light emitting diode as the light source, the life of the light source can be extended. Further, since the light emitting diode consumes less power than the conventionally used lamp, the power consumption of the image display device can be reduced. Furthermore, compared to a video display device using a liquid crystal panel, the optical system of the device is simpler, and a great effect that the device can be downsized can be obtained.

In the second and third embodiments, the case where the light emitting diode is used as the light emitting means has been described. However, an electroluminescent element or a semiconductor laser element may be used instead of the light emitting diode.

(Embodiment 4) FIG. 9 is a configuration diagram of a video display apparatus according to Embodiment 4 of the second invention. In FIG. 9, 41R is a red light emitting diode array in which a plurality of red light emitting diodes as red light emitting means are arranged in a horizontal line, 41G is a plurality of green light emitting diodes as green light emitting means arranged in a horizontal line. A green light emitting diode array 41B, a blue light emitting diode array in which a plurality of blue light emitting diodes as blue light emitting means are arranged in a row in a horizontal direction, and 12 a light beam emitted from each of the light emitting diode arrays 41R, 41G, 41B. A condenser lens 13 for forming an image by illuminating the light, 13 is a condenser lens 12
Is a projection lens for projecting the image formed by the above, 14 is a vertical scanning reflecting mirror for scanning in the vertical direction while reflecting light rays from the projection lens 13, and 16 is a screen.

FIG. 10 is a block diagram for controlling the operation of the video display device shown in FIG. 9. The same components as those in FIGS. 2 and 6 of the first and second embodiments of the first and second aspects of the present invention are described. The same reference numerals are given and the detailed description is omitted. In FIG. 10, 4
2R, 42G, and 42B store video signals from the video signal processing circuit 17 and image memories for each color for converting the timing of the video signals so as to be suitable for scanning by the vertical scanning reflector 14, 43R, 43G, and 43R. 43B is a pulse width modulation circuit for each color for pulse width modulating the video signal from the image memories 42R, 42G, 42B in accordance with the gradation, and 44R, 44G, 44B are pulse width modulation circuits for each color 43R, 43G, respectively. An LED driving circuit for each color for driving each color LED array 41R, 41G, 41B by the video signal for each color processed in 43B, an image position control circuit 45, and a horizontal synchronizing signal H from the synchronizing separation circuit 18 and a vertical synchronizing signal H The position of the image indicated by the currently input video signal is detected by the synchronization signal V, and the pulse width modulation circuits 43R and 43R for the respective colors are detected. G, generates a control signal for controlling the operation of 43B and vertical scanning reflector control circuit 24.

The operation of the video display device according to the fourth embodiment of the second invention will be described below with reference to FIGS.

First, in FIG. 10, the input video signal A is adjusted by the video signal processing circuit 17 and separated into each primary color signal.
The image data is input to the green image memory 42G and the blue image memory 42B. In each of the image memories 42R, 42G, and 42B,
After a video signal for one line in the horizontal direction of the screen is recorded by a control signal from the image position control circuit 45, the signal of one line in the horizontal direction of the screen is converted into video signal data for each line in which the signal is grouped.

The image position control circuit 45 detects the current position on the screen of the video signal input from the horizontal synchronizing signal H and the vertical synchronizing signal V separated by the synchronizing signal separating circuit 18 and indicates the position of the image. Generate control signals. The pulse width modulation circuits 43R, 43G, 43B for the respective colors operate the image memories 42 for the respective colors in response to a control signal from the image position control circuit 45.
The video signal of each line input from R, 42G, and 42B is subjected to pulse width modulation according to the signal level for each pixel. The red LED drive circuit 44R outputs the red L according to the video signal data pulse-width modulated by the red image memory 42R and the red pulse width modulation circuit 43R.
The light emission of the ED array 41R is turned on / off to drive so as to emit light in pulses. The red LED array 41R is formed by arranging a plurality of LEDs in a line in a direction corresponding to the horizontal direction of the screen, and an image display corresponding to one horizontal line of an image is simultaneously performed.

Similarly, the green LED drive circuit 44G and the blue LED drive circuit 44B also drive the green LED array 41G and the blue LED array 41B, and drive one of the images in the horizontal direction.
Images corresponding to the lines are displayed at the same time.

Here, the LED driving circuits for each color 44R, 44R
4G and 44B are similar to those described in the first embodiment, and the LED arrays 41R, 41G and 41B of the respective colors are driven by pulse modulation by supplying a constant current to each LED.
Adjustments can be made to eliminate variations in brightness for each D.

In FIG. 9, the light beams emitted from the LED arrays 41 R, 41 G, and 41 B of each color are condensed by the condensing lens 12 to form an image once, and are projected on the screen 16 by the projection lens 13 in the horizontal direction. Displayed as a line image.

The vertical scanning reflector 14 is controlled by a vertical scanning reflector control circuit 24 to change the angle of the reflector, and operates so as to scan the optical path from each LED in the vertical direction. By performing the vertical scanning in synchronization with the vertical scanning of the video signal, the screen 1
The image of one line in the horizontal direction projected on 6 can be scanned in the vertical direction and displayed as an image.

Here, the scanning of the vertical scanning reflecting mirror 14 is stopped during the period in which each color LED array is displaying one line of video, as described with reference to FIG. 3 of the first embodiment. The operation is controlled so as to move to the next position until the display of the next line image starts. The LED arrays 41R, 41G, and 41B of each color are also driven so as not to emit light while the vertical scanning reflector 14 moves, as described in FIG. 3 of the first embodiment.

The red LED array 41R, the green LED array 41G, and the blue LED array 41B are driven by the video signal thus pulse-width modulated, and the emitted light is vertically scanned by the vertical scanning reflecting mirror 14, whereby: An image can be projected and displayed on the screen 16.

Here, the vertical scanning reflecting mirror 14 can be easily constituted by a movable reflecting mirror such as a galvano mirror or a polygon mirror using a stepping motor. Further, it is clear that the means for changing the optical path of the light beam is not limited to using a reflecting mirror, but may use a prism or the like. In the fourth embodiment shown in FIG. 9, the configuration using the projection lens 13 has been described. However, it is obvious that the configuration without the projection lens may be used.

FIG. 11 is a view showing a display state of an image on the screen 16. Note that FIG. 11 shows a display state using a one-color LED array for easy understanding. As shown in FIG. 11, the light rays from each LED
3 projects one horizontal line on the screen 16. Then, in synchronization with the vertical scanning of the video signal, the video signal is vertically scanned by the vertical scanning reflector 14 and displayed as an image.

As described above, in the image display apparatus of the fourth embodiment, the light emitting diode is used as the light source, the driving of the light emitting diode itself is performed by a signal obtained by pulse-modulating the image signal, and the operation of the scanning optical system is controlled by the light emitting diode. In the low gradation region, the light emission amount of the light emitting diode itself is sufficiently low, so that the display performance in the low gradation region can be improved. The quality can be improved with high contrast.

Further, by using a light emitting diode as the light source, the life of the light source can be extended. In addition, since the power consumption of the light emitting diode is smaller than that of a conventionally used lamp, the power consumption of the image display device can be reduced. Furthermore, compared to a video display device using a liquid crystal panel, a simple effect of the optical system of the device is required, so that a great effect that the device can be downsized can be obtained.

In each embodiment, the case where the light emitting diode is used as the light emitting means has been described. However, an electroluminescent element or a semiconductor laser element may be used instead of the light emitting diode.

[0069]

As described above, according to the video display apparatus of the present invention, the pulse width modulation means for pulse width modulating the electric video signal according to the information of the video to be displayed, and the output signal from the pulse width modulation means The light emitted by the red, green, and blue color light-emitting units, which emit light in a pulsed manner in red, green, and blue, respectively, and the light emitted by the red, green, and blue light-emitting units are spatially separated. Light image scanning means for scanning in the horizontal and vertical directions; and image forming means for imaging light emitted by the red, green, and blue light emitting means on a screen, and the input electric image The light beam scanning means is scanned in the horizontal and vertical directions so as to synchronize with the horizontal scanning and the vertical scanning of the signal, and the scanning of the light beam scanning means is stopped during the period in which the light emitting means of each color emits light. An image is displayed on the screen by using a self-luminous element that emits light by itself as modulation means for converting an electric image signal into a change in light intensity, and the self-luminous element is pulsed. Along with driving by width modulation, by controlling the scanning reflector to stop scanning while the self-luminous element is emitting light from the scanning reflector, the variation in brightness of the self-luminous element is eliminated,
In addition, it is possible to avoid side effects due to the pulse width modulation drive, and it is possible to sufficiently reduce the light intensity in the low gradation region, so that the display performance in the low gradation region can be improved and the display quality can be improved. Can be made favorable with high contrast. Further, there is a great effect that the light source has a long service life and low power consumption, and furthermore, a simplified image display device can be provided by simplification of the optical system.

Further, the video display device of the present invention has a pulse width modulation means for pulse width modulating an electric video signal in accordance with information of an image to be displayed, and a red, green, and green signal respectively based on an output signal from the pulse width modulation means. For red light, a plurality of light-emitting elements that emit light in pulsed blue light are arranged in a row for each color.
Light emitting means for each color for green and blue; light beam scanning means for scanning light emitted by each of the light emitting means for red, green and blue; and light emitting means for each color for red, green and blue Image forming means for forming an image on the screen of the light emitted by the plurality of light-emitting elements in the horizontal or vertical direction of an image based on the input electric image signal. Light emitted from the red, green and blue color light-emitting means by the light beam scanning means in a direction perpendicular to the direction in which the light-emitting elements of the light-emitting means for each color for green, blue and blue are projected in a line. Scanning, and controlling the light scanning unit to stop scanning during the period in which each color light emitting unit emits light, thereby displaying an image on the screen. A self-luminous element that emits light by itself is used as a modulating means for converting an electric image signal into a change in light intensity, the self-luminous element is driven by pulse width modulation, and the self-luminous element emits light from a scanning reflector. By controlling so that the scanning of the scanning reflector is stopped during the period, the brightness variation of the self-luminous element can be eliminated, and the side effect of the pulse width modulation drive can be avoided. Therefore, the display performance in the low gradation region can be improved, and the display quality can be improved with high contrast. In addition, the light source has a long life and low power consumption,
Further, there is a great effect that a compact video display device can be provided by simplifying the optical system.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a video display device according to Embodiment 1 of the first invention.

FIG. 2 is a block diagram for controlling the operation of the video display device of FIG. 1;

FIG. 3 is a state diagram for explaining a relationship between a light emitting state of an LED of the image display device of FIG. 1 and an operation time of a scanning reflector;

FIG. 4 is a display state diagram of an image on a screen by the image display device of FIG. 1;

FIG. 5 is a configuration diagram of a video display device according to Embodiment 2 of the second invention.

FIG. 6 is a block diagram for controlling the operation of the video display device of FIG. 5;

FIG. 7 is a display state diagram of an image on a screen by the image display device of FIG. 5;

FIG. 8 is a configuration diagram of a video display device according to Embodiment 3 of the second invention.

FIG. 9 is a configuration diagram of a video display device according to Embodiment 4 of the second invention.

10 is a block diagram for controlling the operation of the video display device in FIG. 9;

11 is a display state diagram of an image on a screen by the image display device of FIG. 9;

FIG. 12 is a configuration diagram of an example of a conventional video display device using a liquid crystal panel for a video display unit.

[Explanation of symbols]

 11R Red LED 11G Green LED 11B Blue LED 12 Condenser lens 13 Projection lens 14 Vertical scanning reflector 15 Horizontal scanning reflector 16 Screen 17 Video signal processing circuit 18 Synchronous signal separation circuit 21R, 33R Red pulse width modulation circuit 21G , 33G Green pulse width modulation circuit 21B, 33B Blue pulse width modulation circuit 22R, 34R Red LED drive circuit 22G, 34G Green LED drive circuit 22B, 34B Blue LED drive circuit 24 Vertical scanning reflector control circuit 25 Horizontal scanning mirror control circuit 31R Red LED array 31G Green LED array 31B Blue LED array 32R Red image memory 32G Green image memory 32B Blue image memory

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01S 5/40 H01S 5/40 5F073 H04N 5/74 H04N 5/74 H 9/31 9/31 C (72 ) Inventor Atsushi Hatayama 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Junji Masumoto 1006 Odaka Kazuma Kadoma City Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 1006 Omon Kadoma, Fumonma-shi Matsushita Electric Industrial Co., Ltd. 5C080 AA06 CC02 CC03 CC06 DD20 DD26 DD29 DD30 EE28 FF14 JJ01 JJ02 JJ04 JJ06 KK43 5F041 AA12 AA24 BB31 DC07 DC81 EE11 FF06 5F073 AB05 BA09 EA05 EA0 6 EA29 GA37 GA38

Claims (4)

[Claims] 1. A pulse width modulating means for pulse width modulating an electric video signal in accordance with information of an image to be displayed, and self-luminous light emission in red, green and blue in response to an output signal from said pulse width modulating means. For red, for green, for each color light emitting means for blue, and for red, for green, light beam scanning means for scanning light emitted by each color light emitting means for blue in the horizontal and vertical directions spatially, Image forming means for forming light emitted by the red, green and blue light emitting means on a screen, wherein the light beam is synchronized with horizontal scanning and vertical scanning of the input electric video signal. An image is displayed on the screen by controlling the scanning means to scan in the horizontal direction and the vertical direction, and controlling to stop scanning of the light beam scanning means during a period in which the light emitting means of each color emits light. A video display device. 2. A pulse width modulating means for pulse width modulating an electric image signal in accordance with information of an image to be displayed, and self-emission in red, green and blue in a pulsed manner by an output signal from said pulse width modulating means. Red, green, and blue color light emitting means in which a plurality of light emitting elements are arranged in a row for each color, and light beam scanning means for scanning light emitted by the red, green, and blue color light emitting means. And image forming means for forming the light emitted by each of the red, green, and blue color light emitting means on a screen, and a plurality of images in a horizontal direction or a vertical direction of the image by the input electric image signal. The light scanning elements are simultaneously displayed, and the light beam scanning means is arranged on the screen in a direction orthogonal to the direction in which the light emitting elements of the red, green, and blue light emitting means are aligned and projected. In the stage, for red, green, scan light emitted from each color light emitting means for blue, and, during the period of light emission of each color light emitting means, by controlling to stop scanning of the light beam scanning means, An image display device for displaying an image on the screen. 3. The image display according to claim 1, wherein each of the red, green, and blue light emitting means is a light emitting diode element, an electroluminescent element, or a semiconductor laser element. apparatus. 4. The image display device according to claim 1, wherein said light beam scanning means uses a reflecting mirror or a prism to change the direction of the light beam.