JPH0412473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a large, thin display device comprising a plurality of pixel forming units using electro-optical elements such as liquid crystal.

Conventional large display devices include movie projectors and over-the-top displays.
There are various large-sized display devices such as head projectors and those that enlarge and project high-sensitivity cathode ray tube images on the back side of the screen. Here, the latter example as shown in FIG. 1 will be explained as an example of a conventional large display device.

In Fig. 1, numeral 1 is a high-sensitivity cathode ray tube, which has a lens that magnifies the image. 2 is the optical path, 2
A and 2b represent the optical path boundaries. 3 is a reflecting mirror, and 4 is a semi-transparent screen. In addition, to make a color display device, three high-sensitivity cathode ray tubes 1 are used,
It is sufficient to project the three primary colors independently on the screen. Here, a large display device is defined as having a screen size of around 1 m square or more.

The conventional large-sized display device shown in FIG. 1 has a disadvantage that the image brightness is unsatisfactory even with a high-sensitivity cathode ray tube because the enlargement ratio of the image is large. Since it is necessary to have a long optical path length, it is necessary to make the reflecting mirror 3 large or arrange it with a certain depth. In either case, the display device is large and has a large depth, making it unsuitable for use in home televisions and the like. Furthermore,
It has a defect that makes it difficult to match the pixels and colors of the three cathode ray tubes to produce a color image. Therefore, although the device of FIG. 1 appears to be inexpensive to manufacture, it also has defects that make it expensive.

The present invention seeks to eliminate such defects. The object of the present invention is to use an electro-optical element display such as a liquid crystal, which is originally thin, but since the number of multiplexes cannot be large, in order to form a large number of pixels, it is necessary to increase the number of multiplexes at the expense of image quality. The object of the present invention is to provide a thin and inexpensive large-sized display device constructed by a plurality of units in which the total number of pixels is divided to the extent that the total number of pixels is divided.

The present invention will be explained below with reference to the figures. FIG. 2 is a diagram explaining the outline of the present invention, in which a is a cross-sectional view and b is a front view. The figure shows an example in which a large screen is composed of 5×5=25 units. 5 is a translucent screen, 6 is a pixel forming unit, and the screen side is 7.
At step a, this is enlarged like the optical path 8, and at step 7b, there is no blank space between the pixels of the adjacent unit, so that the entire screen can be obtained uniformly. b shows that the 7a square screen is enlarged and displayed on the 7b square screen. The pixel forming unit side shown in FIG. 2 will be explained with reference to FIG. In the following figures, the same numbers represent the same or similar meanings or means. Third
The figures show examples of pixel forming units constituting a large display device according to the present invention with different light sources.
Indicated by c.

10 is a frame of the unit; 11 is a liquid crystal display that is driven with an appropriate number of multiplexes to form a predetermined image; 12 is a printed substrate; a drive circuit 13 that drives and displays the display 11 in a predetermined manner; Connector 1 that connects to data imported from outside
4. Reference numeral 15 denotes a flat light source, which emits thermoelectrons from a fluorescent material coated on a flat surface, or is excited by ultraviolet rays like a normal fluorescent lamp and emits light. If light is emitted on a flat surface, the parallel ray component will be relatively strong. 16 is light source 1
The light source 15 is filtered to suit the wavelength distribution of the light source 15.
is not necessary if the light is emitted with an appropriate wavelength distribution.

17 is a concave lens that changes the optical path and enlarges the image. Since the light passing through the concave lens does not form a real image on the screen 5, the screen 5 is made semi-transparent so that it passes through the light irregularly, so that it looks as if a real image is formed. Of course, a convex lens may be used to form a real image on the screen, but since the optical path becomes long, the depth increases, which is not suitable for thin display devices. Although the concave lenses 17 may be made for each unit, they can be made at low cost by integrally molding them from plastic at positions corresponding to each unit throughout the display device. Reference numeral 18 indicates an optical path of light from the light source 15 outside the pixels of the display body 11 or the image. 19 represents the light from the adjacent unit. By configuring each unit as shown in a, a uniform large screen with no gaps is formed on the screen 5 as shown in b.

b shows an example in which an inexpensive point light source such as a filament lamp 20 is used to obtain a parallel light source. 21 is a parabolic reflector.

c shows an example of another method for obtaining a parallel light source.
Reference numeral 22 represents a rod-shaped fluorescent lamp, and its length extends to each unit arranged in a direction perpendicular to the plane of the paper.

Reference numeral 23 is a reflecting mirror parallel to the fluorescent lamp 22 and having a parabolic cross section, so that almost parallel light can be obtained. Reference numeral 24 indicated by a dotted line is an optical conduit that further improves parallelism. If the parallelism of the light is good, images that are faithful to the original image can be obtained without being affected by adjacent pixels. The light pipe 24 is made of a plurality of thin opaque materials connected to each other and has a rectangular or hexagonal cross section. If the ratio between the cross-sectional opening and the length of the light pipe 24 is sufficient, sufficient parallel light rays can be obtained on the principle that stars can be observed from a well in the daytime. Looking at the unit in Figure 3 from the perspective of thinning, a,
The order is b and c, but from a cost perspective, the order should be reversed.

Next, the display body 11 forming images or pixels used in FIG. 3 will be explained with reference to FIG. 4. Reference numeral 25 denotes a flat substrate made of transparent glass or the like, and includes substrates 25a and 25b.
The LCD is held between the two. The substrate 25a has three common transparent electrodes 26a and 26b arranged in the horizontal direction. Transparent electrodes 27a and 27b are arranged on the substrate 25b divided into upper and lower parts on the plane of the drawing. If the liquid crystal is twisted nematic, the liquid crystal is oriented in a predetermined manner. In this case, although not shown, the board 2
Two polarizing plates are used on both sides of 5 so that the plane of polarization is in a predetermined direction. In this way, the display body 11 can be constructed by sequentially applying scanning signals in the vertical direction and adding pixel data in the horizontal direction, thereby generating a predetermined electric field between the electrodes 26 and 27 and transmitting the uniformly applied parallel light rays. By controlling the amount, FIG. 4 constructs a partial image.
The scanning signal is supplied from a scanning signal generator 32 to the electrodes 26a and 26b via lines 29a and 29b in response to a clock 33 having a predetermined period. The pixel data is transferred from the pixel data 31b to the data drive circuits 30a and 30b.
is applied serially, stored sequentially, latched and held in synchronization with the scanning signal, and applied to electrodes 27a and 27b via lines 28a and 28b. The gradation is shortened by setting the scan signal period to 100% and using gradation data separately provided to the data drive circuit to output the latch-held pixel data. G, R, and B in the data drive circuit 30 indicate the three primary colors green, red, and
It corresponds to blue. 34 is the smallest pixel unit for color display. Corresponding to the electrodes 27, G, R, and B filters are provided in stripes or islands on the substrate 25, the polarizing plate, or another substrate. In the example of FIG. 4, it is shown as an island. In the figure, the minimum pixel is actually 1 x 3 = 3, but the reason why it appears to be 3 x 3 = 9 is because the latter is experimentally found to be more natural as an image.

In the example shown in Figure 4, the number of multiplexes is 2 and the number of pixels is 2 x 4 x 2 = 16. However, with the characteristics of current liquid crystal materials, the opening/closing ratio of the amount of light transmitted and the opening/closing speed The maximum number of multiplexes is 32. If it is more than this, the contrast and brightness will be unsatisfactory.

Therefore, if the large display device of the present invention is applied to a television, the number of effective scanning lines according to the NTSC system will be reduced.
Since it is about 480, 480 ÷ 32 = 15, or as shown in Figure 4, the number of multiplexes is the same, and if they are divided and installed above and below, it becomes 480 ÷ (32 × 2) ÷ 8, depending on the number of horizontal lines, A number of units of 15 or an integer multiple of 8 are required. Display devices with multiple units are a factor in increasing costs from the perspective of assembly, but depending on the type of light source, it is possible to install a wall-mounted TV with a depth of about 50 mm and a screen of 1 m square or more, which has great cost performance. This is a feature of large-sized display devices. Furthermore, since the liquid crystal display itself has low power consumption, if a highly efficient light source is used,
Another feature of the present invention is that a large display device with much lower power consumption than the cathode ray tube method can be obtained.

In addition, the display body 11 that opens, closes, or controls the transmission of light
Although this was explained using a twisted nematic liquid crystal material, a DSM type liquid crystal may also be used. Furthermore,
Other materials having an electro-optic effect such as electrochromics may also be used as long as they have a predetermined light opening/closing speed.

Next, a configuration example in which the large display device according to the present invention is applied to a television will be briefly explained with reference to FIG. In the figure,
35 is a receiving antenna, 36 is a tuner, and 37 is an A/D that converts the selected video signal into GR and B color-coded analog video signals into digital signals.
(analog-digital) converter. The reason why this A/D converter is divided into three series is to reduce the A/D speed. 40 is a large-sized display device according to the present invention, and is shown as a simple unit number of 3×4 or (3×2)×4. Reference numeral 39 denotes a memory means for storing one field or one frame of data of video signals for each color in correspondence with the series of large display devices 40. 38 is a control circuit which refers to the vertical synchronization signal and the horizontal synchronization signal and controls the A/D converter 37.
control for storing the data in the memory means 39;
Data in the memory means 39 is read and controlled to the large display device 40. The reason why the memory means 39 is used here is that the large display device according to the present invention has a defect in that it does not have the number of multi-presses that can be processed in real time. The capacity of the memory means 39 is calculated as follows: 480 (vertical) x 400 (horizontal) x 3 (color) x 3 (gradation bits) ≒ 64K bits x 27.

You only need to use 27 pieces of 64K bit RAM, and with recent advances in semiconductor technology, it has become cheaper each year.
It's not enough to be a problem. Note that in FIG. 5, arrows indicate the outline of the signal flow.

As mentioned above, by arranging a large number of units that control multiple pixels using materials such as liquid crystals that have an electro-optic effect that can control the amount of light transmitted, and enlarging the image of each of these units, it is possible to By filling in the gaps, it is possible to not only obtain a high-quality screen, but also to provide a thin, large-sized display device with good cost performance, which is highly effective.

In other words, it can be replaced with a movie projector, overhead projector, etc., and will bring about a revolution in the video world.

As described above, according to the present invention, a concave lens is used to magnify an image that has passed through an electro-optical element, so the optical path is shortened, and a thin and large display device can be realized.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of an example of a large-sized display device that enlarges and projects images from a conventional cathode ray tube. FIG. 2 is a diagram showing a large-sized display device according to the present invention, in which a is a sectional view and b is a front view. FIG. 3 is a diagram showing an embodiment of a unit constituting a large-sized display device according to the present invention. A shows an example in which the parallel light beams required for the unit are obtained using a plane light source. b shows an example in which the parallel rays required for the unit are obtained using a point light source and a parabolic reflector. Figure c shows an example in which the parallel light beams required for the units are obtained by a rod-shaped light source extending over a plurality of units and a large number of light guide tubes. FIG. 4 is a diagram showing an example in which the display body for controlling the amount of light transmitted through the unit is made of a material having an electro-optic effect, such as liquid crystal. FIG. 5 shows a block diagram when the large display device according to the present invention is applied to a television.

Claims (1)

[Claims] 1. A large number of display units are arranged in parallel, each having a light source, an electro-optical element that electro-optically opens and closes a plurality of pixels, and a concave lens that magnifies an image that has passed through the electro-optical element. A large display device characterized by having a screen on which an image is projected over the entire surface.