JPS58220126A - Display method of medium contrast - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to an improved image display method.

Currently, there are various types of image display devices, and by taking advantage of the characteristics of each, some are suitable for home (personal) use, some are for commercial use, and some are suitable for home (personal) to commercial use. It is widely used. However, these 1 ill 1 display devices have problems in image quality, shape of oxidation, productivity,
It has defects in at least one of five aspects, such as driveability and reliability. For example, cathode 1tl (C'RT)
has a defect in its shape, especially its depth, which is too large, and the liquid crystal displays used for digital displays on watches and calculators have defects such as poor S-image contrast and poor visibility. I haven't gotten anything.

Therefore, the present applicant has proposed a new image display method, an image display element, and a Km image display device that solve these problems in the technical field and produce display effects that have never existed before.

Hereinafter, the image forming base of the image display element according to this ladder will be explained based on the drawings of FIGS. 1 to 6. FIG. 1 is a cross-sectional view of a basic image display element 10, in which (a) shows a reflective type, and (b) shows a transparent type. 1 is liquid layer, 2.3
are a transparent protection plate and a substrate laminated on this liquid layer 1, respectively. Reference numeral 4 denotes a dot-shaped or segment-shaped bubble generating element attached to the inner wall of the substrate 3. The liquids constituting the liquid layer 1 include (1) a colored liquid and (2) a cloudy liquid; the basic components of these liquids are water or various organic solvents used either singly or in combination. Here, ■Colored liquid refers to colored liquids including black that are obtained by dissolving or decomposing various dyes and pigments in the basic composition of the liquid mentioned above, and are transparent or transparent. It doesn't matter whether or not. (A cloudy white liquid is a white or light-colored liquid obtained by dispersing light-diffusing fine particles (regardless of whether they are solids) in the basic composition of the liquid mentioned above. 5゜The thickness of the liquid layer 1 is such that the amount of transmitted light is approximately half or less of the amount of incident light, generally 1011 m to 30 m.
0 μm is desirable. Note that in this case, the reduction of the transmitted scene does not need to cover all wavelengths in the visible range. In other words, it may be a reduction in part of wavelength light in the visible range. This is natural considering that red, blue, and green colors occur due to absorption of some wavelengths in the visible range. However, this decrease in the amount of transmitted light may be due to either absorption or scattering of light. As the transparent protection plate 2, a colorless or light-colored translucent glass or plastic that is as pressure resistant as possible is used. Note that this transparent protection plate 2 may not be used when the display element 10 is arranged horizontally. As the substrate 3, in the case of a transmissive display, a transparent substrate such as glass or plastic is used, and in the case of a reflective display, an opaque substrate such as a silicon or ceramic substrate is used in addition to the above substrate. Bubble generating element 4
Examples include methods that utilize electrolysis reactions, methods that utilize chemical reactions, methods that inject gas into the liquid layer, and methods that use thermal means. Further, thermal means include those using electric discharge, those using radiation beam irradiation, and those using Joule heating rods. In the present invention, only the bubble generating element 4 that uses Joule heat is used.Although this image forming principle enables both transmissive display and reflective display, in the following explanation, transmissive display will be used. Deals with the case of type designation. That is, in FIG. 1(b), consider a case in which the substrate 3 is a transparent substrate at 0.degree.

If no bubbles are generated in the liquid layer l, one liquid layer is colored.If the colored liquid is black, it becomes black, and by applying an electric signal while red, a predetermined (- or plural) bubble generating element 4 becomes transparent. When the heat generating element generates heat, the temperature of the liquid in the liquid layer 1 that is in contact with or in close proximity to it rises due to heat conduction heating, and eventually boils and creates vapor bubbles (hereinafter referred to as sables) in the liquid layer 1. )5 is formed. Generally, if the shape (length and width or diameter) of the transparent heating element is larger than the thickness of the liquid layer 1, the sol 5 will reach the inner surface of the transparent protection plate 2 more easily than if it is smaller. That is, a region where no colored liquid exists appears between the substrate 3 and the transparent holding plate 2. this·
The backlight 30 is transmitted through the transparent protective plate 2 by opening the sol 5. Generally, the pull 5 extends as far as possible over the surface of the transparent heating element, but hardly extends beyond that.

That is, it can be approximately considered that the outline of the transparent heating element is the outline of the opening 5, that is, the outline of the opening. However, each pull 5 that spreads all over the transparent heating element may be a single 79 sol, or it may be a collection of a plurality of pulls. The aperture is determined by the size and shape of the transparent heating element, and can range from 10 μm in diameter to large quantities, as well as 10 μm in width.
A rectangular shape such as ms+ and length 10 is also available. Of course, more can be formed if desired. This kind of Noze pull 5 has a light transmitting effect because Nono sol 5
This is because the vapor constituting the liquid is the vapor of a solvent that is a component of the colored liquid or cloudy liquid, and is not the vapor of the colorant.

The background light 30 is not limited to the case where it is intentionally applied as described above, and may be any of natural light, room light, or reflected light thereof. Furthermore, in order to obtain the display effect, 6f
It is not necessarily required that the tile 5 reach the transparent protection plate 2. If the nosesol 5 does not reach the transparent protection plate 2, image formation (display) is performed based on the difference in shading.

As an application example of the image forming principle described above, dotma) I
) An example of a schematic configuration of an image display element using the Tx display method is shown in FIGS. 2 to 4.

FIG. 2(a) is a plan view of an image display element using a dot matrix display system, and FIG. 2(b) is a sectional view taken along line 1l-I2. Reference numerals 2' and 3' denote a purulent storage plate and a transparent substrate, respectively, which have the same functions as the transparent protection plate 2 and the substrate 3 shown in FIG. 1' is a transparent heating resistance wire whose area other than the foaming point, that is, the display point, is coated with a conductor 4' such as metal, and the protection 8112
A plurality of them are arranged two-dimensionally between ' and the substrate 3'. The transparent heating resistor wire II is a transparent heating resistor, for example, ITO.
It is obtained by forming a film of (indium tin oxide P) by a vacuum evaporation method. And on top of that, metal
For example, a film of Au (gold) is formed by a vacuum sputtering method. Although the metal film does not necessarily have to be transparent,
If it is desired to obtain a transmittance of 50% or more, a thickness of 100λ to 200mm is required in the case of Au. Usually, a chromium film of about 30 mm is attached as an adhesive between the ITO film and the gold film.

Also, if soda glass is used for the tlu substrate 3', K Sin, (silicon dioxide) is coated on the soda glass to template chemical damage to the ITO. Second
The pattern shape as shown in the figure (the size of the transparent heating resistor element is 1
0 μm×10 μm to 1 jlW× 1 mm) can be easily obtained by conventional photolithography techniques. Here, the transparent heating resistance element means a portion of the transparent heating resistance wire 1' that is not coated with a conductor 4' such as metal, that is, a heating portion. however,
The conductor 4' as shown in FIG. 2 is not necessarily necessary;
Although it is preferable not to have it from a manufacturing standpoint, it is necessary to avoid wasting power. Furthermore, in order to prevent damage to the transparent heating resistive element and the conductor 4' and increase durability, it is preferable to coat them with a purulent-retaining film 1 having a thickness of several μm.

The sleep-retaining film 2 is desired to have excellent transparency (not a requirement in the case of reflective displays), insulation, liquid resistance, thermal conductivity, and impact resistance. ~
5iO18i0. There are dielectric materials such as

FIG. 3 is a sectional view showing a schematic structure of an image display element obtained by combining the W elements of the display elements of FIGS. 1 and 2. FIG. Transparent heating resistance wires 1'a and 1'b intersect at right angles with the liquid layer 1 in between, and both transparent heating resistance elements are arranged to face each other at the intersection. In this display element, heating resistance wires 1'a are orthogonal to each other with the liquid layer 1 in between.

The design is such that only when both 1' and b are selected and heat is generated, Seb#5 is formed in the liquid layer 1 in the intersection area of the two. 20' and 20' are liquid layer 1, respectively.
This is an image display element drive circuit that supplies current to desired heat generating resistance wires, ie, the left heat generating resistance wire and the right heat generating resistance wire. FIG. 4 is an explanatory diagram when the image display elements shown in FIG. 3 are driven in matrix. This image display element 10' is
It consists of six axis heat generating resistance wires I, Xm, Xn, Xo, and Xp (these are called row conductors) and Yc, Yd, and Ye moving axis heat generating resistance wires (these are called column conductors). .

When heating current signals are sequentially applied to the row conductors XI, Xm, Xn, Xo, and XpK, the liquid layer corresponding to these row conductors (
(not shown) are sequentially heated linearly, but at this time, the degree of heating is set to be below the boiling point of the liquid, so no vapor bubbles are generated in the liquid layer. On the other hand, a predetermined video signal is applied to the column conductors Yc, Yd, and Ye in synchronization with the application of the heating current signal. By applying this video signal, the liquid layers corresponding to the column conductors Yc, Yd, and YetC are linearly heated, but in this case as well, the degree of heating must be kept below the boiling point of the liquid, so this alone is not enough. No tsukusol is generated in the corresponding liquid layer. but,
At the intersection of the row line and the column line where the heating current signal and the video signal are synchronized, heat is generated from both, causing heating in a Kaga-like manner.

If the number φ is set so that the corresponding liquid layer foams only when heated in an additive manner, a tsukusol 5' is formed at the intersection of the selected row line and column line.

Note that in the above example, even when the driving method is changed as follows, images can be formed in exactly the same way. That is, even if a modification is made in which a video signal is applied to the row lines and a heating current signal is applied to the column lines, the effect is exactly the same. In this way, the image display element illustrated in FIG. 3 is capable of matrix driving as well. As described above, by tripping the heating resistance wires arranged in stripes on both the transparent protection plate side and the substrate side, the following effects occur: (1) The manufacturing process is simplified and the yield is improved.

■ Since the liquid layer is heated from both sides, thermal efficiency is good, and N
.

Of course, it is also possible to drive only one element of the transparent protective plate and the substrate by arranging the transparent heating elements in a matrix. An example is shown in FIG. In the same figure, lla and llb.

11c and lid are both row conductors, and 12a.

12b, 12c, and lid are all column conductors.

All these conductive wires are made of good conductors such as gold, copper, and aluminum. A window (window P) is opened in the insulating layer at the intersection area of the row conductor and the column conductor, and a heating resistor element 13 is formed.
a, 13b, 13c, and 13d are embedded. In such a configuration, it is possible to substantially prevent the occurrence of losstalk, which is inconvenient for image formation faithful to the signal. Furthermore, if a heating resistor having diode characteristics is placed at the intersection of the row conductor and the column conductor, crosstalk can be completely prevented. Effects can be obtained. FIG. 6 is a circuit diagram of a drive circuit for the image display element shown in FIG. 5.

Since the image control signal m generation circuit 1050 is busy with image control signals, the action selection circuit 103, the moving axis selection selection circuit 103, and the axial drive circuits 101a, 101b, . . . 101m are electrically coupled by a plurality of signal lines. , axial drive circuit 1
Each of the output terminals 01a, 101b, . . . 101m is coupled to a predetermined row conducting wire.

There are various ways to connect these output terminals and row conductors, but in order to explain the basic aspect in this specification, there are as many output terminals as there are row conductors, and one output terminal corresponds to one row conductor. We will deal with the case where it is combined with Dynamic axis selection circuit 104, dynamic axis drive circuit 102a, 102b, ・
...102n and column conductors 12a, 12b, ---, 1
The same applies to the relationship between 2n. The action selection circuit 103 selects (switches on) a specific action (6 leads 1%) according to the image control signal. For example, if the action selection circuit 103 selects the row conductor 11c, it issues a lie row selection signal and receives it. outputs an action drive signal to the axis driving circuit 101c and the driving conductor 11c.On the other hand, when a video signal, which is one of the image control signals, is input to the moving axis selection circuit 104, the moving axis is selected in response to the command. The circuit 104 has a predetermined outer axis (the outer center is -)
Select. For example, if the moving axis selection circuit 104
If d is selected, the dynamic axis drive circuit 102d receives the 12d column selection signal issued from the dynamic axis selection circuit 104 and turns on the column conductor 12d. During the application of a behavioral drive signal to a given row conductor, a given column conductor is connected to the column till )5+! 1. Conductive state by selection circuit. (If so, heat generation in the intersection area of that row conductor and that column conductor!1
(Current flows through the resistance element and a tsukusol is generated.
Synchronizing with the application of the nail shaft drive signal to lclC, if the D1 conductor 12d is made conductive by the driving axis selection 1 signal, a sable is generated at the intersection of the row conductor 11c and the column conductor 12d. Next, the row conductor m is selected and a behavior drive signal is applied to the row conductor 11m, and in synchronization therewith, the column conductors 12c, 1
When 2e is made conductive by the moving axis selection signal, l1
Intersections of m and 12C9■ In and 12e (selected points)
Leak also at intersections other than the 6 selection points where ni-sol occurs.
Although the FK current flows, it is generally below the foaming starting current value, so 1. ? In addition, there is no diode P in the heating resistor element.
By providing the function W1, the leakage current can be made even weaker. In this way, the combined shaft drive signal is
An image can be displayed by performing 111-order scanning and outputting a moving axis selection signal in synchronization with the 111-order scanning. Note that the moving axis selection circuit 104 outputs a moving axis selection signal in response to a command by a video signal. At this time, the direction of the current flowing through the heating resistor element does not matter. Such drive circuits and selection circuits are constructed using known techniques using shift registers, transistor arrays, and the like.

When the pull 5 is generated in the liquid layer 1 in this image display element, a sudden increase in pressure is accompanied, so if the liquid layer 1 is constructed in a closed system, there is a risk that the display element will be damaged. Therefore, it is desirable to connect this liquid layer 1 to an airtight chamber or an aggregator to alleviate the increase in pressure in the liquid layer IVC. The liquid layer 1 within the display element may be placed in a state where it communicates with the outside world (open system) or placed in a state where it is isolated from the outside world (sealed system).

Which system is desirable depends on the application.

For example, if it is a portable device, it is natural that a sealed system is desirable.However, the following technical matters are important even in the case of an open system, but they are especially important in a sealed system. The occurrence of pull 5 is accompanied by an increase in the general pressure, but if the increase in pressure is large, pull 5 itself will not occur. Efforts must therefore be made to minimize pressure increases. In addition, due to the occurrence of ・Puru 5, ・Sebru 5
A volume of liquid corresponding to the volume of . Therefore, consideration must also be given to how to contain the liquid that is removed. As mentioned earlier, one way to solve this problem is to attach a transparent protective film to the inner wall of the transparent protective plate or substrate. However, a more effective means is to provide a cavity 15, an example of which is shown in FIG. The cavity chamber 15 and the liquid layer 1 are separated by a flexible membrane (not shown) that does not allow gas or liquid to pass through. With this configuration, the problems of pressure absorption and liquid being removed are solved. In addition, liquid layer 1 liquid repellency (
If the liquid solvent of the liquid layer is aqueous, by constructing it with a water-repellent material, a flexible membrane can be omitted and manufacturing can be simplified. This is because the liquid layer l is automatically stabilized at the boundary between the lyophilic surface 16 and the lyophobic surface 17 according to Helmholtz's minimum free energy principle. That is, the liquid layer 1 tends to stay on the lyophilic surface 16 and stays on the lyophobic surface 17.
I try to stay away from it. In addition, the liquid advances and retreats at or near the interface between the lyophilic surface 16 and the lyophobic surface 17, and the cushioning effect of the meniscus 18 of the liquid is also added to exert a pressure absorption effect. When the liquid is aqueous, K for making the cavity 15 water repellent can be coated with polytetrafluoroethylene or the like. In FIG. 7, the empty rM chamber 15 is provided to surround the liquid layer 1, but this is not necessarily limited to the case shown in FIG. 7, and it may be provided partially. In short, the installation of the cavity 15 is within the technical scope, regardless of its shape, size, and whether it is a closed system or an open system. The internal pressure of the liquid layer 1, that is, the liquid pressure, is desirably set to 760 mmf'Ig (atmospheric pressure) or less from the viewpoint of power saving, stable operation, and safety measures. This is because the lower the liquid pressure, the lower the supply of energy, ie, the lower the temperature, for foaming to occur, and the higher the internal pressure, the higher the damage rate of the display element. In a structure in which the hollow chamber 15 and the liquid layer 1 are separated by a flexible membrane, the liquid pressure is determined by the internal pressure of the hollow chamber 15, the stress of the flexible membrane, and the like. In either case, the liquid pressure cannot be lowered to K below the saturated vapor pressure of W4# of liquid layer 1 at the liquid temperature at that time. Furthermore, if the liquid pressure is lowered too much to the saturated vapor pressure or its vicinity, Blue 5 will occur all the time regardless of the output signal busyness, resulting in a situation where operation stability is lacking. .

Therefore, in order to increase stability, by filling an appropriate amount of normal temperature gas into the cavity 15, the liquid pressure can be increased to 760 vrm 1.
It is preferable to set the pressure to 1 g or less and to a value near or above the saturated vapor pressure. To explain the hydraulic pressure conditions in more detail, it is important to save energy and
In terms of stable operation and stability measures, a suitable condition is to set the hydraulic pressure at 40"C to 760wnaH, 9 or less. However, 1. This is the pressure value when bubbles 5 are not generated.

By setting the voltage to 5 VC, it is possible to save more power than in the case of an open system. In addition, Nonopur 5
The liquid pressure increases and fluctuates depending on the number of nosesols 50 generated, but by appropriately installing the cavity 15, the adverse effects of the pressure increase can be substantially suppressed. Also, since it is usually used at 40°C or lower, 40'C was used as a standard. The discrepancy between the volume of the cavity 15 and the amount of liquid removed by the no-pull 5 is also an important matter for stable operation of the ζ-pull display. Now, assuming that the volume of the cavity 15 is ■, the internal pressure at that time is P, and the temperature is T, the differential form of the Zeil-Charles law is as follows, where △V is the amount of liquid removed by the nozzle. The volume of the cavity 15 is compressed by the inflow, and ΔP is the pressure increase at that time. Note that P is the saturated vapor pressure and the total pressure of a gas at room temperature, but in reality, vapor also liquefies, so the temperature of the paternal line changes, so the above relational expression does not hold strictly, but the general tendency is It can be said that it shows. Therefore, in order to substantially eliminate the adverse effects caused by pressure fluctuations, ΔV/V or P must be set small.

,? The volume of one pull is minute. For example, the size of the heating resistor element is 200 μm x 200 pm, and the thickness of the liquid layer is 1
The volume of the ζ pull in the case of 00 μm is 4 x lo&''. Therefore, if the total compression when any number of sables occur simultaneously is Σi-''s v, then P Σ△V
If /V is set small, no adverse effects of pressure will occur. In addition, although the colorless translucent liquid is not specifically mentioned as a liquid which comprises the liquid layer 1 in the description up to now, this does not mean that the colorless translucent liquid is not included. In the case of an image display element that utilizes scattering by bubbles, a colorless translucent liquid can be an effective display medium liquid.

In this way, the proposal disclosed by the applicant is superior in terms of image quality, productivity, etc., and ranges from relatively simple calculators with few display points (segments) to complex televisions with many display points. It also has a wide range of functions and uses.

By the way, the concentration of the display medium liquid used for such a bubble display is constant, and it is not possible to prepare liquids with various concentrations, as is the case with paint, for example. Therefore, it is very difficult to display an image with gradation using the method of displaying only bubbles of the same size and shape as shown in FIG.

The present invention has been proposed in view of the above-mentioned problems, and it is an object of the present invention to provide a halftone expression method using ζ-pull display that has good responsiveness to tone signals and can faithfully reproduce the tone characteristics of an image. With the goal.

The gist of the present invention is to express the intermediate tone of the no-pull surface by controlling the number of no-pulls generated per unit time by the function of a control system.

The present invention will be described below with reference to drawings of embodiments. Figure 8 shows the waveform of the ξ pulse current applied to the heating resistor element (solid line).
FIG. 4 is a diagram showing a change in volume of bubbles (dotted line) that occurs in response to the change in volume of bubbles.

・The method of applying the ξ pulse current is frequency modulation. Figure 8 (
In A), the pulse width of the pulse current is τ (sec), and the period is a
In the case of τ(sec), the generation period of the no ζ pull is aτ(s
ec). Therefore, the number of pulls generated per sec is l/aτ. That is, the display element is
Blinks Kl/aτ (times) during I (scc). However, if the period τ (SCC) is sufficiently short, the human visual sense cannot follow the changes due to the nature of human vision, and the flickering of the display element will not be felt. Within this flicker-free range, if the number of 161 .zeta. pulls generated is large, the screen becomes bright, and conversely, if the number of bubbles generated is small, the screen becomes dark. In Fig. 8 (I3), the pulse current ξ pulse width is τ (sec) and the period is bτ (sec) (a >
In case b), the bubble generation period is bτ(SeC). Therefore, the number of bubbles generated per sec is 1/bτ. That is, the image display element is ] (
sec), Kf/bτ (times) blinks. 1/bτ> 1
/aτ, so the brightness is perceived more visually than in case (A).

Figure 8 (C) shows the nose width τ (SeC) of the nose current.
, when the period is Cτ(Sec), the bubble generation period is Cτ(sec)(+)>C). Therefore, 1 (s
The number of bubbles generated per ec) is I/cτ (pieces). That is, the image display element has an interval of I (sec) of 1/iT, 1
．． Blinks z'cT (times). ]/cτ>1/1)τ, so the brightness is perceived to be even brighter than in case (B).

Thus, by applying a ξ pulse current to the heating resistor element under the following conditions and controlling the number of S-pulls generated per unit time, it was possible to express four gradations of the bubble element.

In the above embodiment, the bubble element could be displayed in four gradations by changing the bubble generation frequency.
By changing the ζ-pull generation frequency in multiple stages, the gradation can be made even denser.

In this way, by controlling the generation frequency of bubbles, that is, the number of bubbles generated per unit time, it is possible to express the intermediate tone of the S-pull element.

Although a frequency modulation method is suitable for controlling the number of generated bubbles, the present invention is not limited thereto, and an amplitude modulation method, a pulse width modulation method, or a modification thereof may also be used. Furthermore, in the case where one bubble generation and extinction cycle corresponds to one ξ current, the control of the number of ・ξ pulls generated according to the present invention is not limited, and multiple ・ξ This also includes a case where a cycle of generation and disappearance of one bubble is performed. In this case, each of the plurality of ξ pulses may be completely different in waveform, wave height, and ξ pulse width.

Furthermore, the present invention is not limited to transmissive display elements, but can also be used for reflective display elements, and can be applied not only to monochrome displays but also to color displays.

By controlling the number of bubbles generated per unit time, the present invention has good responsiveness to gradation signals and can faithfully reproduce the gradation of an image.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing a conventional image display element that is the basis of the present invention, FIG. 2 is a plan view and cross-sectional view schematically showing an image display element using a dot matrix display method, and FIG. A sectional view schematically showing an image display element obtained by combining the components of the image display element shown in FIG. 2 and FIG. 2, FIG. FIG. 5 is a perspective view schematically showing another image display element using the matrix display method, FIG. 6 is a circuit diagram of a circuit for matrix driving the image display element of FIG. 5, and FIG.
The figure shows a plan view and a sectional view of the JIJ2 cross section of an image display element equipped with a cavity, and FIG. FIG. 3 is a diagram showing the volume change of the generated shear no ζ pull. 1...Liquid layer 2... -Transparent protection plate 3...Substrate 4... Heat generating resistor element. Applicant: Gyanon Co., Ltd. (a) (b) Figure 7

Claims (1)

[Claims] An image display method in which air bubbles are generated in a liquid layer and the air bubbles are used as pixels to develop an image, which includes: expressing intermediate tones by controlling the number of air bubbles generated per unit time. Characteristic halftone display method.