JPH0622256A - Driving device for projection type display device - Google Patents

Abstract

PURPOSE:To transmit high definition picture data without flicker in compliance with an existing transmission standard by scanning two double speed conversion interlace picture signals whose scanning line differs for each half period of a horizontal synchronizing signal and distributing the result to two projection type display units. CONSTITUTION:High definition picture data are decomposed into four picture data (a)-(d) and each of them is transmitted as an interlace signal through transmission systems A-D. The high definition picture data of a scanning line and those at two preceding scanning line in an odd frame are transmitted as interlace signals by deviating a half of the period of the horizontal synchronizing signal. The display device uses double speed converters 41-44 to convert the speed of the signal to be twice and a data distributer 5 distributes the resulting signal to the upper unit for the first half of one horizontal period and to the lower unit for the latter half period. The signals not transmitted in the odd number field are sent and displayed in an even number field similarly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a so-called projection display device, which synthesizes images of a plurality of projection display units on a screen to display a high-definition image.

[0002]

2. Description of the Related Art A CRT is used as a large-screen projection display device.
A method using a (Cathode Ray Tube) or a liquid crystal panel is well known. Among them, the method using a liquid crystal panel is advantageous in terms of downsizing and maintainability, and thus HDTV (High D
Development is underway as a high-definition display device such as efinition TV).

In a conventional projection type display device using a liquid crystal panel, if the number of pixels is further increased to achieve high definition, there are problems in the liquid crystal panel manufacturing technology, drive circuit technology and the like. For example, when the number of pixels increases, the aperture ratio per pixel decreases and the light use efficiency decreases. In order to avoid this, it is necessary to increase the area of the entire liquid crystal panel, but it is very difficult to manufacture a large area of a liquid crystal panel using a TFT (Thin Film Transistor) without defects. , And when the number of pixels increases,
Although the source line must be driven at high speed, the operating speed of the driver IC that drives the source line is considerably lower than the required performance. Therefore, in order to drive at a higher speed, it is unavoidable that the driver ICs are operated in multiple phases. However, with such a configuration, it is difficult to manufacture a substrate that connects the driver IC and the liquid crystal panel.

Due to such a problem, the liquid crystal projection unit alone does not realize high definition, but a projection type in which a plurality of liquid crystal projection units are used to display the pixels so that the pixels are superposed on each other. A display device has been proposed (Japanese Patent Application No. 3-30111).

FIG. 5 shows an example of such a display device. However, for simplification, a case where the images of the four liquid crystal projection units are superimposed will be described here. In FIG. 5, 1 is high-definition image data, 2 is an image data decomposition device,
31 to 34 are transmission systems, and 61 to 64 are liquid crystal projection units. Reference numerals 91 to 94 are examples of the superposition optical system, and here are half mirrors. 8 is a screen.

Now, assuming that there is high-definition image data 1, four image data (a), in which the number of pixels in the horizontal and vertical directions is reduced by thinning out horizontal pixels and scanning lines as shown in FIG.
Decomposes into (b), (c) and (d). The decomposed image data (a), (b), (c) and (d) are supplied to the liquid crystal projection units 61 to 64, respectively, and the superimposing optical systems 91 to 94 superimpose the pixels on the screen 8. indicate.

In the case of the active matrix type liquid crystal panel, since each pixel is a wiring region, each pixel has a light shielding portion as shown by a hatched portion in the left diagram of FIG. By utilizing this fact and superimposing pixels as shown in the right diagram of FIG. 7, high-definition display with double vertical and horizontal becomes possible. As the superposition optical systems 91 to 94, the method of using a half mirror as shown in FIG. 5 is the simplest, but other methods have been proposed.

[0008]

In such a superposition projection method, image data (a) decomposed into four,
When (b), (c), and (d) are video, in consideration of the video data transmission system, it is common to perform interlaced transmission in order to reduce the transmission capacity. Typical systems include NTSC system and HDTV system. When considering a video data storage system such as a VTR, the data is similarly stored by the interlace method.

Therefore, it is important to have an interface with the existing interlace system even when displaying an image in high definition by the superposition projection system. In order to display the image data (a), (b), (c) and (d) which are existing interlaced signals on the liquid crystal projection unit, the following driving method can be considered. However, in either case, since the resolution in the horizontal direction does not change, only the scanning method in the vertical direction will be described. For ease of explanation, as shown in FIG. 8, the image data of each scanning line is represented by a symbol in which some number is attached to ◯, Δ, □, and ×.

In the method shown in FIG. 9, the odd field (a) is used.
, Two scanning lines of ○ and Δ are simultaneously scanned, and □ and × are simultaneously scanned in the even field (b). The image signals of the scanning lines of ○ and □ are transmitted to the liquid crystal projection units AA and BB. The Δ and × video signals are distributed to the liquid crystal projection units CC and DD. In FIG. 9, the broken scan lines indicate that they are not displayed. By this scanning method, the interface with the existing interlace method can be taken, and at the same time,
The horizontal scanning frequency of the liquid crystal projection unit can be the same as the number of horizontal scannings of the input signal.

However, since writing is performed every other field for each pixel, flicker occurs at a frequency of ¼ of the field frequency in consideration of the alternating period unique to the liquid crystal panel. Usually, since the field frequency of an image is about 60 Hz, the flicker frequency is about 15 Hz, and there is a problem that flicker is noticeable. Therefore, the display quality is poor and not practical. Further, in the non-writing field, the electric charge written in the pixel escapes, so that there is a problem that the contrast is lowered.

The present invention has been made to solve the above problems, and an object of the present invention is to display a high-definition image without flicker by using an existing interlaced video signal. A type display device is provided.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0014]

According to the present invention, in order to solve the above-mentioned problems, the present invention inputs 2 × n (n ≧ 1) projection display units by inputting a plurality of interlaced image signals. In the driving device of the projection display device, which is displayed by the above method, and each image is superposed between pixels on the screen, a means for converting the interlaced image signal at a double speed, and two images converted at the double speed with different scanning lines. The most main feature is that a means for scanning the signal for each half cycle of the horizontal synchronizing signal and distributing the signal to the two projection display units is provided.

[0015]

According to the above-described means, first, in the odd-numbered frame, the image data on one scanning line and the image data on the two scanning lines below are shifted from the high-definition image data by ½ of the horizontal synchronizing signal period. Transmitted as an interlaced signal. On the display device side, means for converting this signal to double speed and distributing it to the upper unit in the first half of a certain horizontal period and to the lower unit in the latter half period is provided. In the even field, signals not transmitted in the odd field are similarly transmitted and displayed.

With this structure, high-definition image data can be transmitted according to the existing transmission standard.
For example, for transmission and storage of image data having a definition four times higher than that of HDTV, four transmission systems and storage systems of HDTV standard can be used as they are.

The refresh frequency of the liquid crystal projection unit is 1/2 of the field frequency of the transmission standard.
Therefore, it does not become lower than the flicker frequency of the existing liquid crystal panel. In the prior art, if the flicker frequency is not lowered, the vertical resolution is unavoidably lowered. However, according to the present invention, high-definition display can be performed without lowering the flicker frequency. As a result, it is possible to inexpensively provide a large-screen, high-definition display system that cannot be realized by the existing liquid crystal display device.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the schematic construction of an embodiment of a drive unit for a projection type display apparatus according to the present invention.
˜44 is a double speed conversion device, 5 is a data distribution device, 61˜6
Reference numeral 4 is a liquid crystal projection unit.

The driving device for the projection display device of this embodiment is
As in the conventional technique described above, high-definition image data captured by a camera or a scanner or created by computer graphics is processed into four image data (a), (b) as shown in FIG. ), (C),
(D) is decomposed, and each image data is transmitted to the transmission system A,
It is transmitted as an interlaced signal in B, C and D. Since only the vertical resolution is a problem in the present invention,
As shown in the description of the conventional technique, the original high-definition image data is represented by the data shown in FIG.

As shown in FIG. 2, the data of the scanning lines transmitted in a certain horizontal period are indicated by .smallcircle. And .DELTA. In the odd field and .quadrature., X in the even field, as shown in FIG.

On the display device side, the transmitted signal is converted by the double speed converters 41 to 44 into double speed signals as shown in FIG. This is for reproducing image data of a 1H period twice in a 1H period, and is actually used in a device for converting an interlaced signal into a non-interlaced signal. As a simple device, two line memories for converting a video signal into digital data and storing a digital video signal for one scanning line are provided in parallel, and writing and reading of these two line memories are alternately repeated. Can be realized by

This double-speed converted image data is distributed to each liquid crystal projection unit as shown in FIG. 4 by supplying the selection signal shown in FIG. 3 to the data distribution device 5.
First, in the first period T ₁ of the odd-numbered field, the first scanning line (A-1, B-1 and C of each liquid crystal projection unit is
Image data is distributed and displayed in -1, D-1). In the next period T ₂ , the image data is distributed and displayed on the second scanning lines (A-2, B-2 and C-2, D-2) of each liquid crystal projection unit. After that, it repeats similarly.

Next, in the first period T ₁ of the even field, in the liquid crystal projection units of A and B systems,
The second scanning line (A-2, B-2), in the liquid crystal projection unit of C, D system, the first scanning line (C-1, D-
The image data is distributed and displayed in 1). In the next period T ₂ , the liquid crystal projection units of the A and B systems have 3
The second scan line (A-3, B-3), the second scan line (C-2, D-2) in the C, D system liquid crystal projection unit
The image data is distributed and displayed on. After that, it repeats similarly. In this way, in the odd field and the even field, the combination of the scanning lines of the A and B systems and the C and D systems is shifted by one scanning line so that the original structure of the high-definition image is reproduced.

The image projected by each liquid crystal projection unit is finally displayed on the screen by the superposition optical system as described in the section of the prior art.

As can be seen from the above description, according to this embodiment, it is possible to transmit high definition image data according to the existing transmission standard. For example, for transmission and storage of image data having a definition four times higher than that of HDTV, four transmission systems and storage systems of HDTV standard can be used as they are.

The refresh frequency of the liquid crystal projection unit is 1/2 of the field frequency of the transmission standard.
Therefore, it does not become lower than the flicker frequency of the existing liquid crystal panel. In the conventional technology, if the flicker frequency is not lowered, the resolution in the vertical direction is unavoidably deteriorated. However, according to the present embodiment, high-definition display can be performed without lowering the flicker frequency. . As a result, it is possible to inexpensively provide a large-screen, high-definition display system that cannot be realized by the existing liquid crystal display device.

Although the present invention has been specifically described based on the embodiments, it is needless to say that the present invention is not limited to the above embodiments and various modifications can be made without departing from the scope of the invention. Absent.

[0029]

As described above, according to the present invention,
High-definition image data can be transmitted by the existing transmission standard. In addition, high-definition display can be performed without lowering the flicker frequency. As a result, it is possible to inexpensively provide a large-screen, high-definition display system that cannot be realized by the existing liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a drive device for a projection display device of the present invention,

FIG. 2 shows 1 / 2H of the decomposed image data of this embodiment.
Diagram showing transmission with staggered periods,

FIG. 3 is a diagram showing a double-speed converted image signal of the present embodiment,

FIG. 4 is a diagram showing image data displayed in an odd field and an even field in the present embodiment,

FIG. 5 is a diagram showing an example of a conventional display device,

FIG. 6 is a diagram for explaining how to decompose high-definition image data,

FIG. 7 is a diagram for explaining that an original high-definition image can be displayed by overlapping pixels.

FIG. 8 is a diagram for explaining correspondence between original high-definition image data and a diagram for explanation,

FIG. 9 is a diagram showing image data displayed in an odd field and an even field in a conventional display device.

[Explanation of symbols]

1 ... High-definition image data, 2 ... Image data decomposing device, 31
... 34 ... Transmission system, 41-44 ... Double speed conversion device, 5 ... Data distribution device, 61-64 ... Liquid crystal projection unit, 7 ... Superimposing optical system, 8 ... Screen, 91-94 ... Half mirror.

Claims (1)

[Claims] 1. A projection display in which a plurality of interlaced image signals are input and displayed by 2 × n (n ≧ 1) projection display units, and each image is superimposed between pixels on a screen. In a driving device of the apparatus, a means for converting the interlaced image signal at a double speed and two of the double-speed converted image signals having different scanning lines are scanned every half cycle of a horizontal synchronizing signal to form two projection display units. A drive device for a projection display device, which is provided with a means for distributing.