JPH06334948A - Projection type display device - Google Patents

Abstract

PURPOSE:To provide a liquid crystal projector capable of automatically adjusting the position of a zoom lens so as to obtain a magnifying ratio matched with the size of a projected image. CONSTITUTION:An input signal from a tuner is separated into a video signal and a synchronizing signal by a synchronizing separator circuit 1, the video signal is A/D converted by an A/D conversion part 2 and the converted signal for one line is stored in a line memory 3. The stored picture data are read out by a control part 7 and inputted to a liquid crystal driving part 8 to display the input signal as a picture. The number of horizontal synchronizing signals synchronously separated by the circuit 1 is counted, which size, of high vision size, NTSC size, vista, size, or 'CinemaScope(R)' size, corresponds to the input signal is judged by a judging part 5 and a switching circuit is switched in accordance with the picture size to set up the projecting zoom lens on a position capable of attaining prescribed magnification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector.

[0002]

2. Description of the Related Art In a projection type liquid crystal display for displaying high-definition, the conventional NTSC is displayed on the screen.
If you adjust the position of the zoom lens so that the image from the signal is projected to the maximum size, and if you want to project a different image size from the conventional NTSC signal, such as Vista size or Cinesco size, The position of the zoom lens was adjusted by operation, and adjustment was performed. Fig. 3 (A) shows a high-definition screen 3
1 and the screen 32 by the NTSC signal, the horizontal: vertical ratio (aspect ratio) of the screen is the high-definition screen 3
In the case of 1, the ratio is 16: 9, whereas the aspect ratio of the screen by the NTSC signal is 12: 9. FIG. 3B is a comparison diagram of the high-definition screen 31 and the vista size or cinemascope size screen. While the hi-vision screen 31 has an aspect ratio of 16: 9, the vista size screen 33 has an aspect ratio of 1: 1. It is 0.85: 1, and the aspect ratio of the screen 34 by the cinemascope size signal is 2.35: 1. When the position of the zoom lens is adjusted so that the high-definition image is projected to the maximum size on the screen of the projection LCD that displays high-definition in this way, Vista-sized or cinema-sized images will not be displayed on the screen. Cannot be displayed in size. Therefore, conventionally, the position of the zoom lens has to be readjusted by manual operation.

[0003]

As in the above-mentioned prior art, in order to display the image size different from the image size by the NTSC signal such as the Vista size or the Cinesco size on the full screen, the zoom lens is manually operated each time. It was troublesome to adjust the position of and adjust. It is an object of the present invention to eliminate the above-mentioned troublesomeness and provide an apparatus capable of automatically adjusting the position of the zoom lens so that the enlargement ratio matches the size of the image to be projected.

[0004]

In order to solve the above problems, the present invention determines the type of screen to be projected by a determination unit. This determination unit separates an input signal from the tuner into a video signal and a sync signal by a sync separation circuit, and the video signal is A / D.
The conversion unit performs A / D conversion, and stores it in the memory 3. The stored image data is read out, input to the liquid crystal drive unit, and displayed as an image. Also, with the vertical sync signal as the starting point,
The counter counts the number of horizontal synchronizing signals in the feedback in which the black level of the video signal is continuous, and the image size corresponding to the counted value is determined by the determination unit, and the image signal to be projected is high-definition, NTSC, Vista. It is determined whether the size is a size or a cinemascope size, and the zoom lens is set to a position where a predetermined magnification is obtained according to the type of these image signals.

[0005]

With the above construction, in the projection type liquid crystal display according to the present invention, the counter is used to count the number of horizontal synchronizing signals in the feedback starting from the vertical synchronizing signal and having a continuous black level of the video signal. However, the size of the image signal projected by the determination unit is determined based on this counted value, and the zoom lens is set to a position with a predetermined magnification according to the type of these input signals. Accordingly, it becomes possible to automatically set the magnification at which the zoom lens expands.

[0006]

Embodiments of the projection type liquid crystal display according to the present invention will be described in detail below with reference to the drawings. In FIG.
An input signal from the tuner is separated by a sync separation circuit 1 into a video signal and a sync signal, and the video signal is A / D converted by an A / D converter 2.
It is converted and stored in the memory 3. The stored image data is read by the control unit 7 and input to the liquid crystal drive unit 8 to be displayed as an image. The number of horizontal sync signals separated by the sync separation circuit 1 is counted starting from the rising edge of the vertical sync signal. This is done by counting the number of horizontal synchronizing signals included in the period in which the black level video signal is continuous, by the counter 4, and the discriminator 5 discriminates the counted value. Whether the size is NTSC, Vista size, or Cinesco size is discriminated, and a position control signal is sent to the zoom lens position control unit 6 according to these sizes to set the zoom lens at a position where a predetermined magnification is obtained.

FIG. 2 illustrates a method of setting the magnification when zooming with the projection type liquid crystal display according to the present invention. In the figure, 22 is a vertical synchronizing signal of a video signal, 23 is a horizontal synchronizing signal, and 24 is a video signal of a white or black level of a video. In the figure, the width 25 of the period in which the black level continues from the vertical synchronization signal 22 varies depending on the size of the image, that is, whether the input video signal is high-definition, NTSC, vista size, or cinemascope size. Has become. Therefore,
The size of the image can be determined by counting the number of horizontal synchronizing signals included in the period in which the black level continues.

The discriminating unit 5 detects whether the size of the projected screen is the Vista size or the Cinemascope size, and adjusts the position of the zoom lens so that the image is projected at a predetermined magnification. To do. As shown in FIG. 3, when a Vista size screen is enlarged by 136%, the horizontal size becomes the same as that of HDTV, and the vertical size is about 4% short, but it is almost the same as HDTV vertical size. It will be close. Further, if the Cinesco size screen is enlarged by 136%, the horizontal size becomes the same as the high-definition size, and the vertical size becomes about 24% short. From the above result, the position of the lens is adjusted so that the zoom is applied so that the magnification of the Vista size and the cinemascope size is 136%.

[0009]

As described above, according to the projection type display apparatus of the present invention, the horizontal synchronizing signal is counted by the counter 4, and the counted value is discriminated by the discriminating section 5.
It is determined whether the input signal is HDTV, NTSC, Vista size or Cinesco size, and a control signal is sent to the zoom lens position control section 6 according to these screen sizes, and the zoom lens is set to a position with a predetermined magnification. As a result, full-screen display can be performed automatically, and there is an effect that it does not take time and effort to adjust the zoom.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a projection display device according to the present invention.

FIG. 2 is an explanatory diagram of a method for determining the screen size of the projection display device according to the present invention.

FIG. 3 is an explanatory diagram of a conventional screen size for each type of signal.

[Explanation of symbols]

 1 Sync Separation Circuit 2 A / D Converter 3 Memory 4 Counter 5 Discriminating Unit 6 Zoom Lens Position Control Unit 7 Control Unit 8 Liquid Crystal Drive Unit

Claims (1)

[Claims] 1. An A / D converter for A / D converting a video signal from a tuner, a memory for storing the video signal,
In a projection display device that inputs the stored image data to a liquid crystal drive unit and projects and displays an image, a vertical synchronization signal is used as a starting point, and a horizontal synchronization signal included in a continuous black level period of the video signal is generated. A projection display device comprising a counter for counting the number, a discriminating unit for discriminating the size of the video signal based on the counted value, and a switching circuit for switching the magnification of projection based on the discriminated result. .