JPH04177986A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To display a pattern largely and to enhance the utilizing efficiency of light while keeping the compatibility even when a video image of a broadcast system whose screen aspect ratio is different is displayed by adopting a circular liquid crystal cell. CONSTITUTION:A liquid crystal panel 1 consists of a liquid crystal cell formed to be a circle by aggregating plural picture elements on a substrate 12, a data line drive circuit 13 formed to be an IC chip, a gate line drive circuit 14 and a control circuit 15. A luminous flux reflected in a reflector radiates the entire face of the liquid crystal cell 11 and the shape of the cross section of the luminous flux on a radiation face perpendicular to the optical path direction and its area are the same as those of the liquid crystal cell 11 and no luminous flux radiates to other parts then the liquid crystal cell 11. In this case, the display part of the liquid crystal cell 11 is changed and driven corresponding to the aspect ratio of the display screen. Thus, even when a signal of the broadcast system whose screen aspect ratio differs is displayed, the screen is set larger to enhance the utilizing efficiency of light.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention relates to a liquid crystal display device, and is particularly suitable for receiving television broadcast signals with different screen aspect ratios. .

(Prior Art) A conventional technology will be described with reference to FIGS. 4 and 5.

FIG. 4 is a block diagram showing an example of a conventional projection type liquid crystal display device.

41 is a light source, and the light source 41 emits dispersed light. This dispersed light beam is reflected by the frefter 42 as a light beam. A light shielding plate 43 is provided on the reflector 42 . This light shielding plate 43 has an aspect ratio (hereinafter referred to as aspect ratio).
Apertures corresponding to different television broadcast signals are provided, and a portion of the luminous flux from the reflector 42 is emitted from the apertures. The light beam emitted from this aperture enters a liquid crystal panel 44 arranged on the optical path. The light flux passes through the liquid crystal panel 44 and becomes image light, which is projected onto the screen 46 via the projection lens 45.

Next, in the liquid crystal display device of FIG. 4, a diagram of the liquid crystal panel 44 viewed from the optical path direction is drawn in FIG. 5 in order to explain the difference in light utilization efficiency when the aspect ratio of the screen is different.

The liquid crystal panel 44 includes a substrate section 52 and a liquid crystal cell 53A. The aspect ratio of the liquid crystal cell 53A is NT
The ratio is set to 4:3 in the SC mode, and the light beam emitted from the aperture of the light shielding plate 43 is emitted onto the entire surface of this liquid crystal cell. If we define the ratio of the luminous flux that actually becomes image light among the luminous flux reflected by the reflexor 42 as the light utilization efficiency,
The value is expressed by the area ratio of the light flux irradiation surface 51 assumed to be irradiated onto the liquid crystal panel 44 and the liquid crystal cell 53A.

On an NTSC screen with an aspect ratio of 4:3, the light utilization efficiency is 61%.

In order to explain the case of another method, it will be explained with reference to FIG.

(a) shows the case of high-definition system, in which the part of the liquid crystal panel 53A with an aspect ratio of 4=3 is actually illuminated with light, and the aspect ratio is 16:9. . The light usage efficiency is low at 46%, and the screen is small.

(b) is a case in which an NTSC screen is rotated 90 degrees using a liquid crystal panel 53A, and the part of the screen 53C that is actually illuminated with light has an aspect ratio of 3. :4. The light usage efficiency is also low at 34%.
The screen is also small.

(Problems to be Solved by the Invention) In the above configuration, if the size of the liquid crystal cell is set to a certain aspect ratio, when an attempt is made to display a screen with a ratio different from the aspect ratio of the liquid crystal cell, There are many non-transmissive surfaces on the liquid crystal cell through which light does not pass, resulting in a decrease in light utilization efficiency. Another drawback was that the display screen was also smaller.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that can set a large screen and increase light utilization efficiency even when displaying signals of broadcasting systems with different screen aspect ratios.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the liquid crystal display device of the present invention includes: a light source; a reflecting means for reflecting the light emitted from the light source as a luminous flux; a liquid crystal panel disposed on the optical path of the light beam reflected by the means and having a circular liquid crystal cell; and a drive circuit that changes and drives the display portion of the liquid crystal cell in accordance with the aspect ratio of the display screen. , and a control circuit that controls the drive circuit.

(Function) A circular liquid crystal cell is placed on the optical path of the light beam to ensure compatibility even when displaying images of broadcasting systems with different aspect ratios.

(Example) In order to explain the example of the liquid crystal display device of the present invention, the first
Refer to FIGS. Figure 11 shows the configuration of the liquid crystal panel.

The liquid crystal panel 1 includes a liquid crystal cell 11 formed in a circular shape by aggregating a plurality of pixels on a substrate 12, and a data line drive circuit 13, a gate line drive circuit 14, and a control circuit 15 formed into IC chips. There is. On the entire surface of the liquid crystal cell 11,
The light beam reflected by the reflector 42 (see FIG. 4) is irradiated. The cross-sectional shape and area of the light beam on the irradiation surface perpendicular to the optical path direction are the same as the shape and area of the liquid crystal cell 11, and parts other than the liquid crystal cell 11 are not irradiated with the light beam.

In FIG. 2, components given the same reference numerals as in FIG. 1 have the same functions, and detailed explanations will be omitted. The liquid crystal cell 11 employs an active matrix method.

Each pixel constituting the circular liquid crystal cell 11 has a liquid crystal element and a switching transistor connected to it, and a video signal is supplied through the drain and source electrodes of this transistor, and a scanning signal is supplied to the gate electrode. By doing this, any pixel can be driven.

Therefore, by selecting which transistor to drive, it is possible to display a screen of any size and aspect ratio.

The control circuit 15 selects a pixel that will be the drive start point and a pixel that will be the drive end point of the liquid crystal cell 11 determined by the aspect ratio of the screen, and transmits information on the vertical and horizontal coordinate positions to the data line drive circuit 13 and the gate line drive circuit. 14. That is, if an image is to be displayed on screen 2, coordinates are given to the four corners of screen 2, and Al (XI, Yl), An (XI,
Yn), Bl(Xn, Yl), Bn(
Xn, Yn), the drive start point is AI, and the drive end point is Bn.

The control circuit 15 sends information on the coordinate positions of these two points to the data line drive circuit 13 and the gate line drive circuit 14. The data line drive circuit 13 first starts with AI (Xl, Yl) ~
A video signal is applied to the drain of the switching transistor of each pixel of Bl (Xn, Yl). Further, the gate line drive circuit 14 similarly has AI (Xi, Y
A scanning signal is applied to the gate of the switching transistor of each pixel from l) to BI (Xn, Yl). The data line drive circuit 13 and the gate line drive circuit 14 sequentially repeat this operation, and An (XI, Yn)
A signal is sent to the switching transistor of each pixel of ~Bn (Xn, Yn) to display one screen. However, since the portion of the liquid crystal cell 11 other than the screen 2 is not driven, a non-transparent portion 16 is generated.

Next, a diagram for comparing the light utilization efficiency on display screens of broadcasting systems with different aspect ratios is drawn in FIG.

(a) NTSC screen 2A (aspect ratio is 4:3
) is the case where the image is displayed in the part.

At this time, the driving start point of the liquid crystal cell is Aal (Xal).

Yal), and the driving end point is Ban (Aan, Y
aa) and operates as described above to display the screen.

The light utilization efficiency at this time is 61%, which is equivalent to the prior art shown in FIG.

(b) is a case where an image is displayed on a portion of the high-definition screen 2B (aspect ratio is 16:9). At this time, the driving start point of the liquid crystal cell is Abl (Xbl, Yb1
), and the driving end point is Bbn (Xbn.

Ybn) and operates as described above to display the screen. At this time, the light utilization efficiency was 54%, which was improved compared to 46% in the prior art shown in FIG. 6(a), and the screen was also larger.

(C) is screen 2 of the NTSC screen rotated 90 degrees.
This is a case where an image is displayed in a portion of C (aspect ratio 3:4).

At this time, the driving start point of the liquid crystal cell is Act (Xcl,
Ycl), and the driving end point is Bcn (Xcn,
Ycn) and operates as described above to display the screen. At this time, the light utilization efficiency was 61%, which was improved compared to 34% in the conventional technology shown in FIG. 6(b), and the screen was also larger.

In this way, it is possible to provide a liquid crystal display device that is compatible with broadcasting systems with different display screen aspect ratios and capable of large screen display.

Furthermore, this embodiment has the advantage that the non-transmissive portion 16 of the liquid crystal panel can serve as a function of a light-shielding plate, which was necessary in the prior art.

(Effects of the Invention) As described above, according to the present invention, by adopting a circular liquid crystal cell, even when displaying images of broadcasting systems with different screen aspect ratios, compatibility can be maintained while maintaining compatibility. It is possible to provide a liquid crystal display device that can display a larger screen than conventional ones and can improve light usage efficiency.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the main parts of a liquid crystal display device according to the present invention;
FIG. 2 is a block diagram for explaining the operation of the main parts, FIG. 3 is a diagram showing the operation of the present invention, FIG. 4 is a block diagram of a liquid crystal display device according to the prior art, and FIG. FIG. 6 is a block diagram of the main parts of the display device, and is a diagram showing the operation of a liquid crystal display device according to the prior art. 1...Liquid crystal panel, 11...Liquid crystal cell, 12...
Substrate, 13... Data line drive circuit, 14... Gate line drive circuit, 15... Control circuit, 41... Light source, 4
2...Reflector 13 7'''- Fig. 1

Claims (2)

[Claims] (1) A light source, a reflecting means for reflecting the light emitted from the light source as a luminous flux, and a liquid crystal panel and a display screen arranged on the optical path of the luminous flux reflected by the reflecting means and having circular liquid crystal cells. A liquid crystal display device comprising: a drive circuit that changes and drives a display portion of a liquid crystal cell in accordance with an aspect ratio; and a control circuit that controls the drive circuit. (2) The liquid crystal display device according to claim 1, characterized in that the shape and area of the surface of the liquid crystal panel irradiated by the light beam are approximately the same as the shape and area of the liquid crystal cell.