JPH0353285A - Color image display device - Google Patents

Abstract

PURPOSE:To form a high-definition color image at high speed and to display it be successively arranging an erasing heating means for heating a display area, an image position detecting means and a recording heating means and arranging the erasing heating means and the recording heating means in order that a temperature given to a display medium is controlled at a high temperature. CONSTITUTION:A colored high polymer layer which reversibly transits between a transparent state and a scattering state by heat is formed as a display area consisting of display elements of two or more colors. By giving plural temperatures to the display medium having different transition temperatures in the transparent state and the scattering state between display picture elements of different colors, the color image is formed and displayed. In a process that the display area is led to an image display part where the color image is displayed, the erasing heating means for uniformly heating the display area, the image position detecting means and the recording heating means for heating in an image shape are successively arranged. Furthermore, the erasing heating means and the recording heating means are arranged in order that the temperature given to the display medium by each means is controlled at the high temperature. Thus, the high-definition color image is clearly displayed as a still picture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color display device, particularly a color display device having a polymer layer.

[Conventional technology]

Traditionally, video output from TVs and VTRs, and output from interactions with computers, have been displayed on display monitors such as CRT (cathode ray tube) and TN (twisted nematic) liquid crystal displays, and documents have been displayed using WP (word processors), facsimiles, etc. , high-definition images such as figures have been output and displayed in the form of printed hard copies.

[Problem that the invention is trying to solve]

However, although a CRT outputs a beautiful image when outputting a moving image as described above, when an image remains still for a long time, flicker and scanning stripes due to insufficient resolution deteriorate the visibility.

Furthermore, although conventional liquid crystal displays such as the above-mentioned TN liquid crystal have achieved thinner devices, they still have problems such as the labor involved in manufacturing them, such as sandwiching the liquid crystal onto a glass substrate, and the screen being dark. there were.

Furthermore, CRTs and TN liquid crystals have drawbacks such as the fact that they do not have a stable image memory even during the output of the above-mentioned still image, so the beam and pixel voltage must be constantly accessed.

On the other hand, images printed on paper are high-definition,
In addition, although a stable memory image can be obtained, if a large number of images are used, it takes space to organize them, and it is also a waste of resources if a large amount is discarded. Furthermore, until now, processing such as handling of ink and toner, development, and fixing has been required, and maintenance and supply of consumables have been necessary.

SUMMARY OF THE INVENTION An object of the present invention is to provide a display device that can express high-definition color images, which have conventionally been obtained only as hard copies, with the same sharpness as hard copies, and can repeatedly write and erase color images.

[Means for solving the problem (and action)] The present invention has the following features:
A colored polymer layer that reversibly transitions between a transparent state and a scattering state by heat is formed as a display area consisting of display pixels of at least two different colors on the same surface, and An image display device for forming and displaying a color image by applying a plurality of temperatures to a display medium having different transition temperatures between transparent and scattering states, the image display unit for displaying the color image having the In the process of guiding the display area, a plurality of erasing heating means for uniformly heating the width of the display area, an image position detecting means, and a recording heating means for heating imagewise are arranged in sequence, and the plurality of erasing heating means and a color image display device that forms and displays high-definition color images at high speed, characterized in that the plurality of recording heating means are arranged in an order in which the temperature applied to the medium is controlled to be high. provide.

As the polymer layer that can be used for the colored polymer layer of the present invention, a material exhibiting thermotopic liquid crystallinity is suitable. Examples of this include so-called side-chain polymer liquid crystals in which low-molecular liquid crystals with main chains such as methacrylic acid polymers and siloxane polymers are attached in a pendant manner, and also in the fields of high-strength, high-elasticity, heat-resistant fibers and resins. Examples include main chain polymer liquid crystals such as polyester-based or polyamide-based liquid crystals. In addition, the liquid crystal phase includes smectic, nematic, cholesteric and other phases, and discotic liquid crystals are also used. Furthermore, a polymer liquid crystal having a phase exhibiting SmC'' by introducing asymmetric carbon into the polymer liquid crystal and exhibiting ferroelectricity may also be preferably used.

Specific examples of polymeric liquid crystals that can be used in the colored polymer layer of the present invention are illustrated below, but the present invention is not limited thereto.

H H +CH 2-CH Chi.

(N) (N) CH3 -{:CH　2-CHn.

(Sm) Br (V: In addition, as a solvent for coating or forming a film, in addition to dichloroethane, DMF, cyclohexane, etc., polar or non-polar solvents such as tetrahedrofuran (THF), acetone, ethanol, etc. These mixed solvents are used, and these are selected depending on factors such as solubility with the polymer liquid crystal used, the material of the substrate to which it is coated, wettability with the surface layer provided on the surface of the substrate, and film-forming properties. Needless to say, it is possible.

Below, as a specific example of a polymer liquid crystal, the structural formula (
The basic structure and operation of the present invention will be explained in detail using the liquid crystal represented by 1).

The polymer liquid crystal is dissolved in, for example, dichloroethane, and applied onto a transparent polyester base that has been washed with alcohol using an applicator.
When left in an atmosphere of about 5° C. for about 10 minutes, a white scattering film appears. This film thickness is over 10 μm when the weight percentage of the polymer liquid crystal before coating is 20%.

When the white sheet thus obtained is operated with a thermal head, the transparent parts are fixed according to the character and graphic patterns. When this sheet is introduced onto a black background with an optical density of 1.2, a clear black-on-white display is obtained.

Furthermore, if the sheet is guided onto an ordinary overhead projector, a clear negative projected image in which the characters and pattern portions are projected in white can be obtained.

Next, the entire surface of the sheet on which the above pattern was recorded is
℃ and then kept at about 90℃ for several seconds, the entire surface returns to its original white scattering state, and it remains stable even if returned to room temperature, making it possible to record and display again.

The above phenomenon is caused by the film state below the glass transition point in which the polymeric liquid crystal maintains a stable memory state, the liquid crystal film state which can essentially transition to an optically scattering state, and thereby the isotropic state at high temperatures. It can be controlled because it can take at least three isotropic film states, which are molecular alignments.

Next, using FIG. 3, the principle process for displaying a display medium used in the present invention by providing a polymeric liquid crystal layer on a transparent substrate will be explained.

In FIG. 3, the above-mentioned scattering state is the state indicated by ■ in the figure. When this is heated to T 2 (Tiso = isotropic state transition temperature) J;l as shown in (a) using a heating means such as a thermal head or a laser, and then rapidly cooled, it becomes an almost isotropic state as shown in (■) in the figure. The same light transmission state is fixed. In this rapid cooling state, it is sufficient to naturally dissipate heat from the substrate into the air without using any particular cooling means. This isotropic state is stable at room temperature or room temperature below T+ (Tg=glass transition temperature), and is a stable state as an image memory.

On the other hand, after heating to T2 or higher as in ■a, the liquid crystal temperature T,
When held for I seconds to several seconds between ~T2, the scattering intensity increases again during this holding time as shown in (b), and returns to the original disordered state (■) at room temperature,
This state is stably maintained below T.

In addition, as shown by ■ in the figure, if the liquid crystal temperature is held between T and T2 for a period of about 10 milliseconds to 1 second, the intermediate transmission state can be maintained at room temperature in that part. , it is also possible to use it as a gradation expression.

In other words, in this example, the transmittance or scattering intensity can be controlled by how long the liquid crystal temperature is maintained at room temperature after heating to an isotropic state, and it is stable below T1. It is something that can be maintained. Furthermore, in the above case, the temperature at which the scattering state is restored is faster if it is closer to T2 within the liquid crystal temperature.
When left at the liquid crystal temperature for a relatively long time, it is possible to return to the scattering state (2) regardless of the previous state, even if the material is not heated to the isotropic state.

The polymer liquid crystal film may be formed on a substrate that is not oriented or that has been subjected to extraction treatment in multiple directions using ethyl alcohol, etc.; It is preferable to use a coating form.

As the solvent for the polymeric liquid crystal, it is also possible to add a mixed solvent of a plurality of solvents, a mixture other than the polymeric liquid crystal material, a pigment material, and the like to the extent that it does not adversely affect the coating.

FIG. 2 is a diagram showing an example of the layer structure of the display medium according to the present invention.

In this configuration, a dye having optical absorption at least in the visible range, such as dichroism of blue (B), green (G), red (R), or A polymer liquid crystal containing a non-axial dye is formed into a color pattern such as a color mosaic or stripe by halftone printing or other printing or coating methods.

In order to obtain a desired color, yellow (for example, rLSY116 manufactured by Mitsubishi Kagaku Kogyo Co., Ltd.
”, magenta (LSR-401), cyan (LSB
-335), green (same rLSY-116J and rLS
Mixed with E-335J), Red (mixed with rLSR-405
J or rLSR-401J and rLSY-11
A small amount of various dyes such as 6J) may be mixed in a solvent. A mixture of these dyes exhibits coloring properties. The coating layer thickness of the polymer liquid crystal is 0.5 μm or more, preferably 2 to 15 μm.

In addition, in order for the colored polymer liquid crystal layer 12b to exhibit strong optical scattering properties at the liquid crystal temperature, the amount of the dye mixed with the polymer liquid crystal should be 10% by weight or less, preferably 5% by weight or less.
It is preferably 4% by weight or less, more preferably 1% by weight or more, and preferably 1% by weight based on the solvent used.

In this example, a thermal head with 12 dots per 1 mm is used as an example, and 4 dots per 1 mm are used for each of B, G, and R.
As shown in FIG. 4, the sheet of the display medium formed in lines, that is, 12 lines per 1 mm in total, is heated and scanned on the portion corresponding to G of the color polymer liquid crystal layer 12b. As a result, the polymer liquid crystal in the G portion changes from a scattering state to a filter-like light transmittance exhibiting a green color.

When this is projected onto a screen by transmission or reflection using an ordinary overhead projector or slide projector, green light is projected corresponding to the heated scanning area, and the other areas are dark. Also, B, G
, R. When the polymer liquid crystal in the area corresponding to all of the images is heated and scanned in the same manner, the area becomes filter-like light transmitting in each color, and when this is projected, a nearly white projected image is obtained.

The above projection image is basically a high-contrast image, and various color combinations are possible.In principle, full-color images can be created by adjusting the voltage pulse width etc. applied to the heating head. Vine forms an image.

Please note that this image is taken using fluorescent lighting or EL (electroluminescence).
By arranging a panel etc. as a backlight and devising a display using scattered colors, even better visibility can be obtained when viewed directly, and in this case it is basically possible to form a color image on a white background. can.

In addition, as a method for producing the above-mentioned color polymer liquid crystal, in addition to mixing with the above-mentioned dye in a solvent, color polymer liquid crystal is obtained by copolymerization of a dye monomer and a liquid crystal monomer.
After drying and pulverizing the powder, a mosaic pattern can be obtained by electrostatically coating multiple colored powders on a film, or a color pattern of mosaic or striped pigments can be formed on a substrate, and then liquid crystals can be produced. It is also possible to add monomers to this and carry out copolymerization on the substrate.

The principle of color image formation using the apparatus configuration of the present invention will be described below.

The process principle in this case, which shows an embodiment of the present invention using FIG. 2, is the principle disclosed in Japanese Patent Application No. 63-318610.

In this configuration, dyes having optical absorption at least in the visible range are applied to the transparent substrate 13b such as glass, polyester, etc., such as blue (B), green (G), and red (R).
) dichroic or axes-free dyes, pigments, and other pigments are mixed into polymeric liquid crystals that have different scattering or transparent state change temperatures for each color for halftone printing and other printing. A coating method is used to form an array or random array color mosaic, or a color pattern such as a stripe shape.

Specifically, a colored polymer liquid crystal film is prepared as follows.

First, polymer liquid crystal solids corresponding to each of R, G, and B are pulverized at a temperature below the glass transition point. For example, the particle size is selected to be 20 μm±5 μm, particles corresponding to each color are mixed, and an electrostatic coating machine is used to disperse and uniformly coat the particles.

After this, the entire surface is covered with the most TCL of the PLO that corresponds to three colors.
It is formed into a film by baking at a temperature higher than the TCL.

To obtain each desired color, a small amount of dye is mixed into each polymeric liquid crystal as in the previous examples.

Table 1 below shows examples of combinations of polymer liquid crystals and dyes having different state change temperatures.

Table 1 The polymer liquid crystal (II) and (LSR-405) [as red polymer liquid crystal (R)}, the polymer liquid crystal (I) and (LSR-405)
Y-116) + (LSB-335) [as green polymer liquid crystal (G)}, polymer liquid crystal (Illr) and (LS
Image formation performed on a display medium obtained by combining B335) + (LSR-401) [as blue polymer liquid crystal (B)] is shown below. (Refer to Figure 5. In Figure 2, numeral 15 is a halogen lamp, l6 is a heat insulating member for slow cooling, l7
denotes a contact member for applying heat, and l8 denotes a thermal head.

) (a) The previous image is formed. The shaded areas have high transparency, and the dotted areas have high scattering.

(b) After heating the entire surface to an isotropic phase at the erasing temperature TH (>152° C.), the transparent image is erased over the entire pixel area by slow cooling. (In this case, a halogen lamp 15 is irradiated, and a contact member 17 made of aluminum or the like that is heated by the irradiation is brought into contact with the medium and heated. A heat insulating member 16 such as a surface heater is provided near the medium to keep the medium at a certain temperature. (C) According to the B (blue) signal, the actual heating temperature of the medium of the thermal head 18 is THH (instantaneous temperature of the medium) 152.
'C) The applied voltage (or current) is adjusted to apply write scanning to the medium. As a result, R, G,
Color pixels corresponding to all B {polymer liquid crystal (n), (
I). (III)] is made transparent.

(d) Erasing temperature TM (110°C<TM<approx. 130°C
(120'CTg (m) approximately +10℃)} is heated over the entire surface and then slowly cooled, the transparent state of the color pixels (polymer liquid crystals (n), (I)) corresponding to R and G is erased. , B are visible.

(e) According to the G (green) signal, the actual heating temperature of the medium of the thermal head is THM (the instantaneous temperature of the medium is 110°C).
<THM<140°C (120°C Tg (I[I)
(approximately +20°C)} and write scan is applied to the medium. As a result, the color pixel corresponding to G in the heating section {
Polymer liquid crystal (technology)} becomes transparent. (The transparent image in B remains displayed without being affected by the heating of the THM.) (f) Erasing temperature Tt. By heating the entire surface to [77°C < T L < approximately 85°C (approximately 75°CTgCI>+lO0C)] and then slowly cooling it, the color pixel corresponding to R {polymer liquid crystal (■)} enters the scattering state. The image is erased, and a G transparent image is formed in addition to the above-mentioned B transparent image.

(g) According to the R (red) signal, the actual heating temperature of the medium of the thermal head is THt. [The instantaneous temperature of the medium is 77
'C < T HL < approx. 95°C (75°CTg (
I) Approximately +20°C)} and apply write scanning to the medium. As a result, the color pixel {polymer liquid crystal (■)} corresponding to R of the heating section becomes transparent, and the color image shown in (h) is formed.

In the image forming processes (b) to (g) above, (b)
) is performed when image formation is repeated.

Further, the above operations (a) to (g) may be operated independently or in combination as appropriate.

For example, if only the G transparent image is displayed, (b), (e
), (f) operations, if you want to display B transparent and R transparent images, (b), (c), (d),
All you have to do is perform the operation in (g).

According to the above embodiment, precise positioning control between the color pixels and the writing means is not required, and a good image can be formed relatively easily.

Hereinafter, the color image forming apparatus of the present invention shown in FIG. 1 will be explained in more detail.

In FIG. 1, rollers each having a built-in halogen lamp are suitable as the contact members 31 to 33, as shown in FIG. 5, respectively.

The temperature of the contact member 31 is controlled to be the highest temperature TH shown in the principle process, and the process (b) is performed using this and the heat retaining member 31a.

Next, the image position detection means 7l detects markings (not shown) written on the medium, detects passage of the image display area, and synchronizes from this detection signal to determine the highest recording temperature THH. The above process (c) is performed by the thermal head 21 provided.

Here, the types of markings mentioned above include markings with different optical reflectances or transmittances.
l may be one that detects this optical difference, or the marking is based on physical unevenness,
The detection means 7l may be a sensor that comes into contact with this unevenness and detects its passage. Other image position detection means 72
．． The same applies to 73.

Next, the contact member 32 is controlled to have a temperature TM such that TM<TH, and the process (d) is performed using this and the heat retaining member 32a.

Thereafter, the process (e) is carried out by the thermal head 22 which receives a marking detection signal from the detection means 72, and then the process (f) is carried out by the contact member 33 and the heat retaining member 33a, which are controlled to the temperature TL such that TL<TM. After that, THL< T I{M
The process (g) is performed by the thermal head 23 that provides the recording temperature THL.

After the display medium l moves as described above and an image is formed by the transparent parts of each color, once the movement is stopped in the display section, the illumination optical system shown by 50 to 54 causes
Color images are displayed clearly.

The illumination optical system shown here is disclosed in Japanese Patent Application No. 1-104493 and Japanese Patent Application No. 1-1140 previously proposed by the applicant.
This is described in Japanese Patent Application No. 91, and allows the complementary colors of the light passing through the formed transparent portion to be confirmed, that is, the colors resulting from the mixture of scattered colors are displayed.

For example, a part of the image where R, G, and B are all transparent is colored black, and a part where only R is transparent is colored cyan, which is a mixture of B and G, or a part where R and B are made transparent and G is colored black. A portion in a scattered state is displayed in a green color.

Also, the part where all R, G, and B remain in a scattered state is visually recognized as white, and in principle, color image information is displayed on a white background, which is very beautiful.

When an image is recorded on a medium in this apparatus, the medium is moved at a constant speed, and further features of the present display apparatus for adding more stability to image formation in such driving will be described below.

The above features relate to the slow cooling heat retention members 31a, 32a, and 33a.

Here, as examples of combinations of each color and material of polymer liquid crystal in the display medium used in the present invention, in addition to those shown in Table 1, as design combination examples, the liquid crystal temperature width ΔT=Tiso-Tg is as follows. Relatively large difference (R ~ 40
℃, G~55℃, B~70℃) may be a combination of materials. The relationship between the above ΔT and the speed during erasing is such that the larger ΔT is, the higher the scattering speed (during erasing) is.

Therefore, as a further feature of the apparatus of the present invention, the slow cooling holding members 31a, 32a, and 33a are configured to be different from each other depending on the color material composition of the medium used, thereby achieving the process (b). , (d
). The stability of the scattering balance of each color in (f) is improved.

Specifically, for the design example of the polymer liquid crystal for R, G, and B, the slow cooling heat insulating member 33a is set to have a longer slow cooling time in order to reliably eliminate the R use in process (f); Next, in process (d), the slow cooling time is shortened in the order of the slow cooling heat insulating member 32a for reliably erasing the G use, and the slow cooling heat insulating member 31a for ensuring the B use in process (b). Various configurations are possible. This is shown in Figure 6.

According to the color display device of the present invention as described above, a high-definition color image can be beautifully displayed as a still image.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a color image forming apparatus according to the present invention, FIG. 2 is a schematic diagram of a partial configuration of an image forming apparatus according to the present invention, and FIG.
The figure is a diagram showing the relationship between temperature and transmittance (scattering intensity) to explain the principle of the display layer of the present invention, Figure 4 is a configuration diagram of the display medium of the present invention, and Figures 5 (a) to ( h) is a diagram for explaining the image forming method of the present invention, and FIG. 6 is a structural diagram of a heat insulating member for slow cooling. In the figure, reference symbol l 2 3 12a 12b 13a 13b 15 l6 l7 18 2l 22 23 21a, 22a, 23a 3l 32 33 Contact member TM Contact member TL Image forming medium Thermal signal means Medium holding means Polymer liquid crystal layer Polymer liquid crystal layer Base body Heat retention member for slow cooling of halogen lamp Contact member Thermal head Thermal head TH}l Thermal head THM Thermal head THL ・・・・・・・・・・・・・・・Protein roller contact member TH 32a ,33a ・・・・・・・・・・・・・・・・・・
・Thermal insulation member 40b for slow cooling...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・Roller fluorescent light lens light diffuser plate・・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・Light reflection ■■ ・・・・・・・・・・・・・・・・・・・・・・・・ Matte black painted surface (light absorption surface) Equipment exterior 73・・・・・・・・・・・・・・・・・・・・・
Image position detection means polymer liquid crystal layer substrates 31a, 40a, 50 5l 52 53 54 60 71, 72, 101 102 are shown. (e) (c! Zōro-sou pull X included) (Elimination (3) ? Ryo Ikuko BB i name title ■'6h) (chi) (}t)

Claims (2)

[Claims] (1) A colored polymer layer that reversibly transitions between a transparent state and a scattering state due to heat is formed as a display area consisting of display pixels of at least two different colors on the same surface, and between the display pixels of the different colors. An image display device that forms and displays a color image by applying a plurality of temperatures to a display medium that has different transition temperatures between transparent and scattering states due to heat, the image display section displaying the color image. In the process of guiding the display area, a plurality of erasing heating means for uniformly heating the width of the display area, an image position detection means, and a recording heating means for heating imagewise are sequentially arranged, and one of the plurality of 1. A color image display device, wherein the erasing heating means and the plurality of recording heating means are arranged in such order that the temperature applied to the medium is controlled to a high temperature. (2) The color image display device according to claim 1, wherein the configuration of the erasing heating means is made different depending on the liquid crystal temperature range of each color material of the medium.