JPS6341078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel color display method using a passive display device.

In recent years, displays have been developed by controlling the optical properties of ferroelectric materials such as light emitting diode (LED) displays, electroluminescent (EL) displays, plasma displays, electrochromy (EC) displays, and PLZT using electric fields. Various display devices have been developed, such as devices and liquid crystal (LC) displays.

On the other hand, attempts have been made to colorize various display devices, but the reality is that so far nothing practical has been achieved.

In other words, the most well-known color display method is the method using a color cathode ray tube, but this not only requires high voltage and large power consumption, but also requires a large device and poor display contrast in bright locations. There are disadvantages such as a decrease in In order to eliminate these drawbacks, various thin display devices such as LED, EL, plasma, EC, or LC displays are being developed, but it is actually quite difficult to display them in color. It is.

For example, LED, EL, plasma, EC displays, etc. have drawbacks such as being unsuitable for displaying natural colors due to limited emission colors, and requiring high power consumption or driving voltage. Furthermore, if an attempt is made to display a predetermined color by arranging cells emitting different colors in order to change the emitted light color, the resolution will decrease and the manufacturing of the display cells will become difficult.

Although the LC display is superior in the above points,
It is necessary to provide a color filter in each display segment that is formed at high density (requires considerable ingenuity in the method of forming the filter or the selection of the material for the filter), and there are currently very few systems that have been put to practical use.

The present invention has been made in view of the above-mentioned points, and its main purpose is to provide a color display method that can perform color display of any tone.

Another object of the present invention is to provide a color display method that allows high-resolution display using a display surface with a simple configuration.

Still another object of the present invention is to provide a practical color display method that can perform color display without forming a color filter in each display segment.

The color display method of the present invention that achieves the above object is a display method that performs display by selectively driving a plurality of segments provided in a passive display device, in which a plurality of color signals are transmitted for each color. It is characterized in that each signal is applied to a temporally separated passive display device, and each color is illuminated at a timing corresponding to each color signal.

In this way, multiple color signals are temporally separated for each color and applied to the passive display device, and each color to be displayed is illuminated at a timing corresponding to each color signal. There is no need to provide a large number of cells for each segment, and color display of any tone can be performed using display cells with a simple configuration.
In particular, the color display method of the present invention is suitably used for LC display devices and the like among passive display devices.

The basic principle of the present invention will be explained below with reference to an example in which a natural color display is performed using an LC display device, but the present invention can also be applied to display devices using various media having an electro-optic effect. can.

In the case of conventional natural color display, the signal obtained from the original is separated into three primary colors by appropriate means, and each signal is applied to a specific segment of the display surface for display.

In addition, in the additive color method, the three primary colors are R (red) and G.
(green) and B (blue), but in the subtractive color method, M (magenta) and Y
(yellow) and C (cyan) are used.

FIG. 1 schematically shows a display surface when a switching element such as a TFT (thin film transistor) is provided on a substrate surface using the additive coloring method. That is,
Driver elements 2, 2', 2 such as TFTs are installed at the intersections of the row wirings 1a, 1a', 1a'', 1a, 1a''''' and the column wirings 3, 3', 3'', 3, 3'''''. Each of these segments is provided with filters for the three primary colors R, G, and B, and one pixel is constructed from each set of filters for these three primary colors. has been done.

Further, each segment is formed with sufficient density so that it cannot be separated by the human eye, and by selecting these segments, a natural color display is performed.

The display method of the present invention differs from the above-mentioned conventional method in which segments of the three primary colors are separated positionally within the display surface, in that each color is illuminated continuously within an extremely short period of time. This allows for color display.

The display surface of the cell used in this display method has the same configuration as that used in conventional monochrome (single color) LC displays, as partially shown in Figures 2a and b. good. That is, these figures show a cell that performs display in the transmission nematic TN mode, for example, and FIG. 2a shows its plan view, and FIG. 2b shows the line segment of FIG. 2a.
A cross-sectional view along AA′ is schematically shown. As is clear from FIG. 2b, the display cell C includes the liquid crystal layer 11, the spacer 10, the substrates 7 and S on which the transparent electrodes 8, 4'', 4, etc. that sandwich these are provided, and (the polarization direction is 2)
It consists of linear polarizing plates 12 and 13, etc.
In the liquid crystal layer, liquid crystal molecules are aligned parallel to the substrate in directions perpendicular to each other (homogeneous alignment), so that no light is transmitted when no voltage is applied between the electrodes. 6 and 9 are protective layers provided as necessary to prevent the electrodes 8, 4'', 4 from coming into contact with the liquid crystal layer 11.

Also, as shown in FIG. 2a, the gate lines 1a, 1a'... and the source lines 3, which are apparently orthogonal to each other,
3', switching elements 2, 2', 2'', 2... (CdS, CdSe, Te,
(composed of a semiconductor such as amorphous Si) is provided. When displaying a large number of segments as described above, a display cell in which each segment is provided with a switching element such as a TFT is preferably used in the present invention in terms of crosstalk and responsiveness.

The switching elements 2, 2', 2'', 2...
As shown in FIG. 2b, the rectangular gate electrodes 1, 1', 1'', 1... connected to the gate lines 1a, 1a'... through the insulating layers 5, 5'... Also, switching elements 2, 2', 2'', 2...
Source lines 3, 3'... are connected to one end, and drain electrodes 4'', 4 having a predetermined shape constituting a segment are connected to the other end. (The figure shows an approximately square case. (However, it can be polygonal, circular, or oval.)

In addition, on the opposite side to the observation side indicated by the arrow OB, there are illumination means of three primary colors L _R (red), L _G (green) L _B
(blue) are provided, and these are configured to irradiate the display cells with light of three primary colors in synchronization with selectively applying voltage to predetermined segment electrodes.

The display cell having the basic configuration described above is driven according to the block diagram shown in FIG.

For example, each color signal of the three primary colors R, G, and B S _R , S _G ,
S _B is temporarily stored in the first memory M ₁ for one screen, and is processed by the clock signal CL ₁ before the signal for the next screen is sent (that is, within the vertical retrace time). The signals stored in M ₁ at one time are transferred to a second memory M ₂ . At this time M ₁ becomes empty,
Preparations are made to accept the next screen's worth of signals. The clock signal _CL1 drives the memory _M1 to transfer signals only when the gate _G1 is opened by the synchronization signal _SY1 .

On the other hand, each color signal (S _R , S _G , S _B ) sent to the second memory _M2 has a time T to display one screen.
The source line of the display cell C is shifted by 1/3 of the time and the timing is shifted (3, 3', etc. in Figure 2a above).
It is sequentially operated by the clock signal CL ₂ and the changeover switch SW ₁ so as to be sent out. the switch
SW ₁ applies a clock signal CL ₂ to sequentially switch and read out the color signals S _R , S _G , and S _B stored in the memory M ₂ every 1/3 of the time for one screen. Clock signal that synchronizes memory with synchronization signal SY ₁
Switched by CL ₃ (not shown). The color signals sent from the second memory _M2 are stored in the shift register RG for one column, and the synchronization signal is
Gate opened and closed by SY ₂ (vertical scanning signal)
G ₂ to the on-state gate line of the display cell C scanned by the scanning circuit SC (1a, 1a'... in FIG. 2a described above) using the synchronizing signal SY ₂ The voltage is applied to predetermined segments (4'', 4, etc. in FIG. 2a described above) through the connected TFTs.

In addition, irradiation means for R, G, and B three primary colors is operated by switch SW ₂ in synchronization with clock signal CL ₃ .
By L _R , L _G , L _B (connected to power supply E),
The display surface of display cell C is illuminated. For example, at the moment when the R signal is applied to the display cell C, the illumination by L _R is carried out, and at the moment when the B signal is applied to the display cell C, the illumination by L _B is carried out, and so on. will be carried out. The signal of each color can be selected for a short time so that almost no flicker is noticeable to the viewer. For example, in a typical TV image, the display time T of one screen is approximately 1/30 seconds, and each color signal is applied to the display cell at approximately 1/90 seconds, and it is possible to simultaneously illuminate the color in synchronization with the signal. .

The color display method of the present invention can take various forms. For example, regarding the number of memories for storing signals, multiple memories are not necessarily required as long as one memory has sufficient capacity. Alternatively, the first memory and the second memory may be used alternately to store and read out image signals.

The memories M ₁ , M _{2 ,} etc. may be either analog or digital, but the memory and shift register must be of the same type (as the memory).

For the display mode, please refer to the above nematic TN.
The mode is not limited to the display mode, and any display mode such as DSM or phase change type may be used, and any of the projection type, reflection type, or transmission type may be used. It is particularly preferable to use the display method of the present invention in a projection display device. Depending on the display mode employed, suitable optical detection means such as a reflector, a λ/4 plate, or a polarizing plate are provided as appropriate.

In order to improve the contrast, it is preferable to use means such as a light diffusion plate or an optical fiber hologram plate so that the light from the illumination means effectively reaches the display surface of the cell.

For example, as shown in FIG. 4a, a display cell C is formed by sandwiching a liquid crystal layer 11 between two substrates 14 and 15.
When used in DSM mode, the substrate 1 closest to the observation side
4, a hologram plate HB is provided, and illumination light (L _R , L _G , L _B , etc.) can be made incident on the hologram plate. In this way, the light incident on the plate is almost diffracted into the cells, and the scattered light generated in the selected segments is transmitted to the viewing side, allowing color display to be performed.

In FIG. 4b, a light diffusing member LS such as a light diffusing plate or an optical fiber (the side closer to the substrate 15 is made light diffusing) is laminated on the substrate 15, and the member LS is laminated on the substrate 15.
Light sources such as lamps and light emitting diodes L _R , L _G ,
A method of providing L _B is shown.

According to the color display method of the present invention, a small and economical color display can be obtained by using a simple monochrome display cell. or,
As long as the image signals are temporally separated and applied to the display cells, not only can color displays of desired tones, not just natural colors, be easily obtained; The pixel density can be displayed in color, and good results can be obtained in terms of resolution.

The color display method of the present invention is suitably used in various display devices such as slim and compact watches, various panel displays for calculators, small televisions, monitors for video cameras, and the like.

[Brief explanation of drawings]

FIG. 1 is a schematic illustration of a display surface used in a normal color display method, FIG. 2a is a plan view showing a part of a cell used in the present invention, and FIG. 2b is a cross-sectional view thereof. FIG. 3 is a block diagram showing an example of the color display method of the present invention, and FIGS. 4a and 4b are diagrams of another embodiment of the cell used in the present invention. In the figure, 1, 1', 1'', 1... gate electrode, 1a, 1a', 1a'', 1a, 1a'''''... gate line, 2, 2', 2'', 2... semiconductor, 3, 3 ′、
3″, 3, 3′′″…source line, 4, 4′, 4″,
4
...Drain electrode, 5,5'...Insulating layer, 6...Protective layer, 7,S,14,15...Substrate, 10...Spacer, 11...Liquid crystal layer, 12,13...Polarizing plate, L _R ,
L _G , L _B ...Illumination means, C...Display cell, HB...Hologram plate, LS...Light diffusive member.

Claims (1)

[Claims] 1. In a color display device having a plurality of segments, a means for emitting light sources of a plurality of colors in a fixed switching order, and a means for emitting color signals corresponding to the illumination of the plurality of colors at regular time intervals in synchronization with the illumination. A color display device comprising means for selectively driving a plurality of segments corresponding to each color signal by applying voltage to the display device.