JPS5937523A - Smectic liquid crystal display body - Google Patents

Abstract

PURPOSE:To improve thermal responsiveness, more paticularly a cooling speed, to improve high speed responsiveness and to enable partial rewriting with a simple means by constituting a substrate on one side of a liquid crystal display cell with alumina ceramics, and utilizing the heat and electric field effect of the smectic liquid crystal. CONSTITUTION:The liquid crystal side of a sintered alumina substrate 401 is polished to a specular surface, whereafter an Al layer is vapor deposited thereon and is etched to provide striped Row electrodes 402. On the other hand, transparent column electrodes are provided on a counter transparent glass substrate 403, and a smectic liquid crystal 406 is sealed between both substrates 401 and 403. Since the substrate 401 is thin and has good heat conduction, the cooling of the liquid crystal 401 is effected quickly, and since the writing and erasing speed of the liquid crystal 406 can be increased, the display cell of high density and high responsiveness utilizing heating and electric field effects is obtd. as a display body for a word processor or the like. The high speed responsiveness is improved additionally if a copper plate for heat radiation is brought into tight contact with the outside of the substrate 401 and the substrate is forcibly cooled.

Description

[Detailed Description of the Invention] Currently, TN using two O-base plates and nematic liquid crystal
(Twisted Neat) Liquid crystal displays are widely used in calculators, middle-sized machines, and for displaying one or two lines of characters. However, since these are driven by a multiplex method using a voltage averaging method, they are not suitable for display bodies that require higher density.

Particularly recently, there has been a strong demand for high-density, 7-lat panels for comviator terminals, and accordingly, it has been proposed to develop a display using a smectic phase that can be expected to have a higher density in place of the conventional TN type liquid crystal. .

For example, an attempt is made to display characters, graphics, or moving images by controlling the ordered state and random state of the smectic A phase using both heat and voltage application means. The principle can be explained by the diagram schematically shown in FIG.

When a smectic liquid crystal is heated to a temperature above the tariff point Tc, the liquid crystal becomes isotropic. (101) At this time, if the liquid crystal is rapidly cooled without applying a voltage, it passes through the nematic phase (102) and the random smectic phase (
103) or seconds, light scattering occurs in the peripheral light. On the other hand, if the cooling is softened while applying a voltage of 7 reshold voltage vth or higher to the nematic l crystal that appears during cooling, a highly ordered smectic phase (105) that does not cause light scattering occurs. form a mountain.

The coolness of this display is to control and display this light scattering state and the two smectic states without light scattering by heating-cooling and condensation of the presence or absence of voltage. As a heat source, a method using a laser and a method using resistance heating are also being considered.

Specifically, the following matrix display has been proposed using a resistance heating method.

The liquid crystal is heated linearly by one ttt tangent line shown in FIG. 2 (201). A number of these heating resistors A11l are arranged on the board, and as shown in FIG.
-1, Row-2, F(1?/l -3,...
It forms... The video signal is the Col of the display
umn Electric MJj O-1, C-2, O-3...
The 〇 addresses applied to .

First Rnw-1i? A heating pulse is applied to the row 1. While the top of the row 1 is being uniformly heated, the video rows are successively attached to the shift register.

At the same time as the heating pulse goes off, a video signal is applied to each column, and depending on the signal, scattering or transparent dots are formed. This signal is applied during the cooling period of the edge after the application of the heating pulse (in effect, it is valid only while it is in a nematic state!!!).

For example, 3I thickness, 2 glass substrates, Row tit t
ii is metal, aolurrIn'ei If is ITO, 250 Row and 240 Column,
It has been reported that a character cell with a pitch of 37 smm ([contact wheel 0.325 shoulder]) and an effective area of 94 x 90 m/ was prototyped, and according to K, it was 11ine approximately 10rns.
EC writing speed and power consumption when sending ¥t 1
5W has been reported.

The writing speed is determined by the fc thermal response characteristics of the substrate, and the cooling speed is particularly important. Therefore, in order to shorten the address time and ensure high-speed response, it is necessary to improve this thermal response, especially the cooling speed.The above-mentioned display requires several seconds to display one screen. be. In addition, since the cooling speed is slow, when partial rewriting is performed, the temperature will rise compared to the surrounding area for one inefe, and the omitted conditions will become all, and it will not be possible to obtain an 11-minute display, or if the , the display disappears. In order to eliminate this drawback, a temperature sensor may be provided for each line, or a temperature sensor may be provided for each line.
However, attempts have been made to control each writing condition using the CPU, but the number of attempts has not increased in practice.

It is an object of the present invention to overcome such drawbacks and to provide a cell that can be partially rewritten without complicated means.

A more detailed explanation of the display body of the present invention will be given below based on examples.

FIG. 6 shows a drive circuit F9 for a thermal writing type display.
It is a logical diagram. The video signal output from the character generator (303) passes through the latch (304'I) and is introduced as data into the shift register (506>).
It is held flat in the latch (307). During this time, a scan signal or Roqn (1111) is input from the control circuit (311) to the shift register (312), and through the driver, the Row' of the liquid crystal display is
The first 11ine ('R-1) of ilt pole 1 μm1 is heated.

Apply a heating pulse of 41" fi. As soon as the heating pulse is applied and ends, in synchronization with the control circuit,
The latch (307) is connected to the video signal t; all ao1wm O+, Ox
−・・・・・applied to an, the first 11ine
(R-1) is written. Video signal is Co1utn
While the heating voltage is applied to the ROw side, the heating current applied to the ROw side heats the fifth-order Row 1ine (R-2''lK is applied, and the R-21ine is heated).

While the R-2 heating pulse is applied, the video signal is transferred from the shift register to the latch and the heating pulse O
At the same time as ff, all 0o1urnn, 21st ine (R-
2) can be applied as the data signal. In this way, the writing continues in sequence (l-5, R-4, . . . until one screen is written). As mentioned above, this writing speed can be completed in a shorter time as each 1 ins thermal response speed is faster, and writing can be completed in a unit time.
do a lot The heating speed increases as the applied voltage increases, but the cooling speed depends on natural heat dissipation phenomena. receive.

For example, in the conventional cell, as mentioned earlier, 11 inches
A ¥11 input speed of 10rnsec was required. Therefore, the maximum percentage characteristic of this display is, for example, 5001v'ne to display a certain high resolution and high density.
This would require about 5 seconds, making it impractical. The problem here is that, taking the case of the 250 x 240 display mentioned above as an example, if you write something that takes about 2.5 seconds and immediately erase it, and then try to display something else, it will take about 2.5 seconds. If there is no interval of 15 seconds, proper display will not be possible.

This means that when this cell is fully charged, it will take approximately 15 seconds to return to its initial state at 7IcfC. This is because if we apply a heating pulse or a dynamic voltage under the same conditions as the beginning, the conditions will be met and tr < .As a result of our investigation into the reason for this, we found that We found that the biggest factor was the heat dissipation characteristics of the cell substrate.Based on this, we prototyped a smectic heat ν1 cell with the cell structure hk shown below.
m sec, 250 x 240 full screen writing i,! Less than 5 seconds. This was repeated at a low rewrite interval of 58 ec to obtain a display with 111 write and erase cycles.

Example 1 A sintered alumina substrate with a thickness of ζ05. The side in contact with the liquid crystal in FIG. 4 is mirror polished. A ν layer was deposited on this substrate at a thickness of 5000 m, with a pitch of 0375 mm, "+lf
Striped sow N tr with a salary width of 0.325 million a
It is provided by etching 250 pieces of i602. On the other hand, on the opposing transparent glass substrate 603, ■ TO aolu
There are 240 rrm 11f camellias 604. Nu,
Spacer 405 between alumina substrate and transparent glass substrate
A smectic liquid crystal 406 (Sm range - 10°C to 53°C) containing alkyl biphenyl as a main component is sealed through the tube. In addition, inside the cell, the liquid crystal is vertically aligned.
The processing method is vertical processing.

The operating conditions are: RoW side heating heating electrode cost power is approximately 60W
is required, and the signal electrode also has a voltage of 5 to 10V, compared to the conventional 5 to 10V.
This cell required approximately 15V, but the response speed was 11 intt 5 m5ec, and the response speed was approximately 1
．． I was able to write with 55ttc. Regarding the screen repetition cycle, whereas the conventional method requires a minimum of 15 seconds, it was possible for the car to obtain a clear image even if the screen was displayed repeatedly at intervals of approximately 5 seconds.

Embodiment 2 In Embodiment 1, it is possible to write and erase at 5 second intervals, and it is used for writing and erasing each screen. r
, for example, I found out that the TR car can be used enough for Ichiko city storybook purposes, but for example, in a display that requires partial erasure or rewriting, V↑, and its repeated circumference Jll + 5 seconds is j11 ≦
It is too crowded to use, and the scope of use at the main store is being narrowed down.

In Example 2, in order to further improve the coil strength, a prototype was manufactured in which a metal plate 507 was closely contacted with the back surface of the alumina substrate of Example 1.

In order to improve the contact between the metal plate and the alumina ceramics M1, flatten the alumina ceramics side with a plane vapor deposited F#450.
8 was provided and brought into close contact with the copper heat sink 507.

(Figure 7, see) As a result, the heat dissipation J+ was tested once, and it became so that it could not withstand repeated use for 2 seconds at 1111.

This 1 has made it possible to partially rewrite parts of the image, making it possible to use it as a word processor and as a display.

tIIa, depending on the application if the configuration is lenient, t+
:q It can be inferred from Example 1.2 that by forcibly cooling the heat dissipation plate with cooling water, a faster repeating cycle 3 (c) can be obtained.

[Brief explanation of the drawing]

Fig. 1: Principle diagram of thermo-electric writing/erasing method of display using smectic phase. (1) Thermal hysteresis 2 (II
) Thermal hysteresis in a no-voltage state Figure 2: Heat using smectic phase - 11., Flat) Matrix address display using write-in erasure method, electrode configuration of S channel. 201...Metal 'Pow' (pow camellia) 202.
...Work TO transparent electrode (On1wns seal) Figure 3...A block diagram of the drive circuit of the matrix address display body used in the main damage example. 301...CPU 302...Frame memory 303...Character, generator 30
4...For character generation, latch 305...
...Parallel-to-serial conversion circuit 306...Data signal shift register 307...Data latch 508...Cheetah signal driver 309.
...Oscillator 310...Address, counter 311...
...Control unit 312...Scan side, shift register 313...Driver 314...Matrix display Fig. 4...
FIG. 1 is a cell configuration diagram of Example 1 of the present invention. 401 ・・・・・・Alumina seven mix substrate 402・
...Fulmi Row 11f pole 403 for heating...
...Transparent glass substrate 404...ITOCi No. 405...
. . . Spacer 406 . . . Smectic liquid crystal FIG. 5 . . . Cell configuration diagram of Example 2. 507... Heat dissipation assembly plate 508... More than a porcelain vapor deposited layer Developer NEI Co., Ltd. Suwa Seikosha Furijin Patent attorney Saiju Tsumu

Claims (1)

[Claims] In a display cell using smectic thermal and W field effects, at least one substrate of the cell is composed of alumina ceramics.
l, fi display.