JPH11142805A - Projection type picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to display a normal picture even when convergence adjustment is executed by adjusting a display position of a projected image in a projection type pictre display device using plural liquid crystal(LC) panels. SOLUTION: Together with the control of a picture display position on an LC panel 1 by controlling a horizontal scanning start signal generated from a horizontal scanning control circuit 13 and a vertical scanning control signal generated from a vertical scanning control circuit 14, a picture display control circuit 17 controls a horizontal blanking signal generated from a horizontal blanking control circuit 15 and a vertical blanking signal generated from a vertical blanking control circuit 16 respectively based on the horizontal scanning start signal and the vertical scanning start signal so that a relative position between a blanking part and a video signal to be fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device (International Patent Classification G02F 1/13) for projecting images displayed on a plurality of liquid crystal panels 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 image display devices for enjoying powerful images. As a conventional large-screen image display device, there has been a projection television using a CRT. However, since a CRT is used for an image display unit, there is a limitation in miniaturization of the device due to physical restrictions of the CRT. . In order to eliminate this limitation and reduce the size of the device, a projection type image display device using a liquid crystal panel for an image display unit has been proposed.

FIG. 3 is a block diagram showing an example of a conventional projection type image display device using a liquid crystal panel. Generally, in a projection type image display device using a liquid crystal panel, three liquid crystal panels for red, green and blue are used to obtain a color image. In FIG. 3, a lamp 5 as a light source is shown.
The radiated light from 1 and the reflected light reflected by the reflecting mirror 52 are collected by a condenser lens 53 and then decomposed into red, green and blue primary color lights by color separation dichroic mirrors 54 and 55. Each primary color light is a liquid crystal panel 57 for red,
The light is guided to the liquid crystal panel for green 58 and the liquid crystal panel for blue 59, is synthesized by dichroic mirrors 60 and 61 for color synthesis, and is projected on a screen 64 by a projection lens 63. The total reflection mirrors 56 and 62 are for changing the optical path of the light beam.

In order to display an image on the screen 64 in the projection type image display device, a liquid crystal panel 57 for red
So-called convergence adjustment is required in which the positions of the images projected from the green liquid crystal panel 58 and the blue liquid crystal panel 59 are adjusted to match on the screen 64. Generally, the convergence adjustment is often performed by a method of mechanically adjusting the mounting position of the liquid crystal panel. An example of a mechanical convergence adjustment method is disclosed in, for example, Japanese Patent Laid-Open No. 5-236487. On the other hand, for mechanical convergence adjustment, there is a method of performing convergence adjustment by electrically adjusting the position of an image displayed on a liquid crystal panel. An example of the electrical convergence adjustment is described in, for example, Japanese Patent Application Laid-Open No. 3-139622.

[0005]

A blanking process for non-display is performed on a video signal input to the liquid crystal panel by making a period other than a video portion such as a blanking period a black level signal. ing. Blanking is red,
Green and blue video signals are commonly performed, so in a projection type image display device using an electrical convergence adjustment method of adjusting the position of an image displayed on a liquid crystal panel as described above, convergence adjustment is performed. The relative positions of the display unit on which images can be displayed on each liquid crystal panel and the image blanking unit differ.

For this reason, when the screen position is moved, there is a case where one liquid crystal panel is an image portion and another liquid crystal panel is a blanking portion at the end of the display portion of the liquid crystal panel. There is a problem that one or two of the green and blue images are not displayed, and the image is not displayed correctly. The present invention has been made in view of the above, and an object of the present invention is to provide a projection-type image display device that can correctly display an image even when an electric convergence adjustment that adjusts a position of an image on a liquid crystal panel is used in the convergence adjustment. And

[0007]

According to another aspect of the present invention, there is provided an image display apparatus for projecting images displayed on a plurality of liquid crystal panels onto a screen. The liquid crystal display device further comprises means for independently hiding a part of an image displayed on a plurality of liquid crystal panels for each liquid crystal panel. According to the present invention, in a projection type liquid crystal display device having a function of independently adjusting the display position of an image on each liquid crystal panel, a specific color can be obtained at the edge of the screen even when the adjustment of the display position of the image is performed independently. It is possible to provide a projection-type image display device capable of displaying a correct image without being displayed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image display device according to the present invention is an image display device for projecting images displayed on a plurality of liquid crystal panels onto a screen. A vertical scanning control signal for controlling image display, a means for independently controlling a horizontal scanning control signal for controlling image display in a horizontal scanning direction of the plurality of liquid crystal panels for the plurality of liquid crystal panels, and the vertical scanning control; Means for independently hiding a part of an image displayed on the plurality of liquid crystal panels with respect to each liquid crystal panel based on a signal and the horizontal scanning control signal, and setting a non-display area of the plurality of liquid crystal panels on the plurality of liquid crystal panels. Moving in at least one of the vertical scanning direction and the horizontal scanning direction independently of the image display position of the liquid crystal panel. An effect that can be displayed correctly image even been adjusted independently of the display position of the image. Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

(Embodiment) FIG. 1 is a configuration diagram showing a configuration of a projection type image display device according to an embodiment of the present invention.
1 is a liquid crystal panel, 2 is a display pixel portion for displaying an image on the liquid crystal panel 1, 3 is a transistor for controlling image display on the display pixel portion 2, and 4 is a transistor for displaying an image on the liquid crystal panel 1. A horizontal scanning driver circuit for performing horizontal scanning, a vertical scanning driver circuit for similarly performing vertical scanning, a video signal line 6 for transmitting a video signal from the horizontal scanning driver circuit 4, and a video signal line 7 A scanning signal line for transmitting a scanning signal from the vertical scanning driver circuit 5, a video signal processing circuit 11 for processing a video signal into a form for displaying an image on the liquid crystal panel 1, and a video signal processing circuit 12 for converting a video signal into a horizontal synchronization signal 13, a horizontal separation control circuit for generating a control signal for the horizontal scanning driver circuit 4, and 14 a control signal for the vertical scanning driver circuit 5. Vertical scanning control circuit for generating, 15
Is a horizontal blanking control circuit for generating a blanking control signal in the horizontal direction of the image displayed on the liquid crystal panel 1, and 16 is a vertical blanking control circuit for generating a blanking control signal in the vertical direction of the image displayed on the liquid crystal panel 1. A control circuit 17 is an image display control circuit that controls the horizontal scanning control circuit 13, the vertical scanning control circuit 14, the horizontal blanking control circuit 15, and the vertical blanking control circuit 16.

In the projection type image display device, for red, for green,
Image display is performed using three liquid crystal panels for blue,
FIG. 1 shows only one liquid crystal panel 1 for simplicity. In addition, a general liquid crystal panel has a large number of display pixels, for example, (horizontal) 640 pixels × (vertical) 480 pixels in the display pixel portion, but is omitted in FIG. 1 for simplicity. .

An image is displayed on the liquid crystal panel 1 by a horizontal scanning driver circuit 4 generated by a horizontal scanning control circuit 13 and a vertical scanning driver circuit generated by a vertical scanning control signal 14 generated by a vertical scanning control circuit 14. 5 is performed. In this embodiment, a case is shown in which a horizontal scanning start signal 21 and a horizontal scanning clock signal 22 are used as horizontal scanning control signals, and a vertical scanning start signal 23 and a vertical scanning clock signal 24 are used as vertical scanning control signals. The image display of the liquid crystal panel 1 in the horizontal scanning direction is performed by sampling a video signal with a horizontal scanning clock signal 22 on the basis of a horizontal scanning start signal 21, and a vertical scanning start signal 23 in the vertical scanning direction. With reference to the vertical scanning clock signal 24, the vertical scanning driver circuit 5 determines the position in the vertical scanning direction of the pixel where the video signal sampled by the horizontal scanning driver circuit 4 is written.

An image display control circuit 17 controls the horizontal scanning control circuit 13 to change the timing of the horizontal scanning start signal 21 and the video signal by moving the horizontal scanning start signal 21 so that the image displayed on the liquid crystal panel 1 is changed. Move the horizontal display position of. Similarly, the image display control circuit 1
Reference numeral 7 controls the vertical scanning control circuit 14 to change the timing of the vertical scanning start signal 23 and the video signal by moving the vertical scanning start signal 23, thereby changing the vertical display position of the image displayed on the liquid crystal panel 1. Move. By changing the timing of the horizontal scanning start signal 21, the vertical scanning start signal 22, and the video signal in this manner, the liquid crystal panel 1
The position of the image displayed above can be moved in the horizontal and vertical directions.

A horizontal blanking control circuit 15 generates a blanking signal in the horizontal direction of a video signal from a horizontal scanning start signal 21 and a horizontal scanning clock signal 22 generated by the horizontal scanning control circuit 13. The horizontal blanking signal can be easily generated by counting the horizontal scanning clock signal 22 using a counter circuit or the like based on the horizontal scanning start signal 21. Similarly, the vertical blanking control circuit 16 generates a blanking signal in the vertical direction of the video signal from the vertical scanning start signal 23 and the vertical scanning clock signal 24 generated by the horizontal scanning control circuit 14. The vertical blanking signal can be easily generated by counting the vertical scanning clock signal 24 using a counter circuit or the like with the vertical scanning start signal 23 as a reference. The horizontal blanking control circuit 15 and the vertical blanking control circuit 16 are also controlled by the image display control circuit 17, and the position where the image is blanked can be moved by changing the timing of the generated blanking signal.

The video blanking circuit 18 includes a horizontal blanking signal generated by the horizontal blanking control circuit 15,
Blanking is performed by switching the video signal to a black display level by a vertical blanking signal generated by the vertical blanking control circuit 16, so that the blanking section is not displayed on the liquid crystal panel 1.

FIG. 2 is a state diagram showing a state of blanking for an image displayed on the liquid crystal panel 1. In FIG. 2, the description is made using two liquid crystal panels for green and red, but the same applies to three liquid crystal panels including a blue liquid crystal panel. FIG. 2 shows, as an example, a case where the mounting position of the liquid crystal panel for green and the liquid crystal panel for red is shifted, so that the projected image of the liquid crystal panel for red is shifted to the left with respect to the projected image of the liquid crystal panel for green. ing. In this state, the timing of the horizontal scanning start signal of the liquid crystal panel for red is advanced from the horizontal scanning start signal of the liquid crystal panel for green, and the position of the image displayed on the liquid crystal panel for red is moved to the right. The adjustment can be made by matching the positions of the green and red projected images above.

However, the blanking portion of the red liquid crystal panel is based on the horizontal scanning start signal, and the position of the blanking portion on the red liquid crystal panel does not move. The position of the blanking portion is different from red and green, and green or red is displayed on the screen, and a correct image display is not performed.

Therefore, in this embodiment, the image display control circuit 1
7, when the timing of the horizontal scanning start signal 21 is changed by controlling the horizontal scanning control circuit 13, the horizontal blanking control circuit 15 is simultaneously controlled to change the timing of the horizontal blanking signal in the reverse direction. Control is performed so that the position of the blanking portion with respect to the video signal is constant. By controlling the position of the blanking portion with respect to the video signal to be constant,
Even if the horizontal position of the image displayed on the LCD panel is moved, the specific relationship is displayed at the edge of the screen because the positional relationship between the display part and the blanking part of the projected image of each LCD panel on the screen matches. It is possible to prevent the image from being displayed incorrectly.

Although the display in the horizontal direction has been described here, the same applies to the display in the vertical direction. In this way, the blanking signal applied to the video signal is generated based on the scanning start signal and the scanning clock signal which are the scanning control signals of the liquid crystal panel, and the timing of the blanking signal is linked with the timing of the video signal and the scanning start signal. The convergence adjustment that adjusts the position of the image projected on the screen by electrically moving the image position on the LCD panel by controlling the The positional relationship between the display portion and the blanking portion of the projection image is maintained, and a great effect that the image is correctly displayed can be obtained.

[0019]

As described above, according to the projection type image display apparatus of the present invention, the means for electrically moving the position of the image displayed on the liquid crystal panel and the display of the screen in conjunction with the image display position are provided. By using the blanking means that can adjust the non-display portion, even when performing the electric convergence adjustment by electrically moving the display position of the image, a specific color is not displayed at the edge of the screen It is possible to provide a projection-type image display device capable of performing correct image display.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a projection type image display device according to an embodiment of the present invention.

FIG. 2 is a state diagram showing a state of a blanking portion for an image of the apparatus.

FIG. 3 is a configuration diagram showing an example of a configuration of a conventional projection image display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Display pixel part 4 Horizontal scanning driver circuit 5 Vertical scanning driver circuit 11 Video signal processing circuit 12 Synchronization separation circuit 13 Horizontal scanning control circuit 14 Vertical scanning control circuit 15 Horizontal blanking control circuit 16 Vertical blanking control circuit 17 Image Display control circuit 18 Video blanking circuit

Claims (2)

[Claims] 1. An image display device for projecting images displayed on a plurality of liquid crystal panels onto a screen, wherein a part of an image displayed on the plurality of liquid crystal panels is independently controlled for each liquid crystal panel. A projection-type image display device comprising means for displaying. 2. An image display device for projecting images displayed on a plurality of liquid crystal panels onto a screen, comprising: a vertical scanning control signal for controlling image display in a vertical scanning direction of the plurality of liquid crystal panels; Means for independently controlling a horizontal scanning control signal for controlling image display in the horizontal scanning direction of the plurality of liquid crystal panels for the plurality of liquid crystal panels, and based on the vertical scanning control signal and the horizontal scanning control signal. Means for independently hiding a part of an image displayed on the plurality of liquid crystal panels for each liquid crystal panel, and vertically scanning a non-display area of an image independently of an image display position on the plurality of liquid crystal panels. A projection type image display device, wherein the projection type image display device is moved in at least one of a direction and a horizontal scanning direction.