JP2614082B2 - Display medium, display method and display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention outputs an image in response to an image signal output from a floppy disk, an optical disk, a magneto-optical memory medium, a computer, or the like, or a facsimile signal or other image signals. The present invention relates to a display medium, a display method, and a device therefor, and more particularly to a display medium, a display method, and a device therefor for outputting diversified color images.

[Prior art] Conventionally, CRT (CRT) and T
High-definition images such as documents and figures by WP (word processor) or facsimile have been output and displayed on paper as hard copies printed out, on an N (twisted nematic) liquid crystal display monitor.

However, although the CRT outputs a beautiful image for the above-described moving image output, it has a drawback that a flicker or a scanning stripe due to insufficient resolution lowers visibility of an image that has been stationary for a long time.

Further, in the conventional liquid crystal display such as the above-mentioned TN liquid crystal, although the thickness of the device has been reduced, the production effort such as sandwiching the liquid crystal between a pair of glass substrates, and the screen is dark. There was a problem.

Further, the CRT and the TN liquid crystal have a drawback that the beam or the pixel voltage must be constantly accessed even during the output of the still image because there is no stable image memory.

On the other hand, images output on paper can be obtained as high-definition and stable memory images, but if they are used too much, they require space for organization and waste large amounts of resources if they are discarded. There are drawbacks.

On the other hand, attempts have been made to use a polymer liquid crystal as a display medium for outputting and displaying a color image. For example, Japanese Patent Application Laid-Open
JP-A-154340, JP-A-62-66990 and the like have proposed recording media using cholesteric polymer liquid crystals. However, the above proposal is directed to light of a specific wavelength, and does not provide sufficient performance as a display medium.

Further, as display media, JP-A-62-14114, JP-A-62-278530, and display media reported in JP-A-62-278529 are known. It is not enough for displaying color images.

On the other hand, a polymer liquid crystal in which a dichroic dye is added for the purpose of coloring the polymer liquid crystal itself or a dye residue is copolymerized as shown in JP-A-58-176205 has been proposed. However, a product having sufficient contrast and good color purity has not been obtained.

On the other hand, it has also been proposed that a low-molecular-weight cholesteric liquid crystal, which is not a high-molecular liquid crystal, is arranged in a planar manner to change the hue by an electric field. [Molecular Crystal Liquid Crystal by Uchida, Shisid and Wada (T.Uc
hida, C. Shishido and M. Wada `` Mol.Cyst.Liq.Cyst. '' 3
9 , 127 (1977)] However, in this method, the hue can be changed only by applying an electric field, there is no holding function, and the definition is determined by the electrode that can be driven. Was difficult to display.

[Problems to be Solved by the Invention] The present invention has been made in view of such a situation, and expresses a high-definition color image conventionally obtained only as a hard copy with the same sharpness as a hard copy. It is another object of the present invention to provide a display medium capable of repeatedly displaying and erasing a color image, a display method thereof, and a display device.

[Means for Solving the Problems] and [Action] That is, the present invention relates to a display medium in which polymer liquid crystalline compounds having different glass transition temperatures and phase transition temperatures are laminated as display layers. A display medium characterized in that the temperature range from the glass transition temperature to the phase transition temperature of the high-molecular liquid crystalline compound of the layer does not overlap.

Further, the present invention, the glass transition temperature and the phase transition temperature of the polymer liquid crystal compound is different from each other is laminated as a display layer, and from the glass transition temperature of the polymer liquid crystal compound of each display layer to the phase transition temperature. In a display medium in which the temperature ranges do not overlap, the optical density of each display layer is controlled independently for each display layer by collectively modulating the temperature of the polymer liquid crystalline compound of each display layer. Is a display method.

Further, the present invention, the glass transition temperature and the phase transition temperature of the polymer liquid crystal compound is different from each other is laminated as a display layer, and from the glass transition temperature of the polymer liquid crystal compound of each display layer to the phase transition temperature. In a display medium in which the temperature ranges do not overlap, two or more heating means are provided in a direction in which recording and erasing are sequentially performed on the display medium, and the heating means sequentially selects each pixel of the display layer. This is a display method characterized by controlling the optical density of each display layer for each pixel independently by collectively modulating the temperature of the polymer liquid crystalline compound of each corresponding display layer.

Further, the present invention, the glass transition temperature and the phase transition temperature of the polymer liquid crystal compound is different from each other is laminated as a display layer, and from the glass transition temperature of the polymer liquid crystal compound of each display layer to the phase transition temperature. A display medium whose temperature ranges do not overlap, a means for sequentially selecting display pixels of a display layer of the display medium, and a means for sequentially performing recording / erasing on the display medium.
A display device comprising a heating means having the heating element head described above.

Further, the present invention, the glass transition temperature and the phase transition temperature of the polymer liquid crystal compound is different from each other is laminated as a display layer, and each display layer from the glass transition temperature of the polymer liquid crystal compound to the phase transition temperature. A display medium having a non-overlapping temperature range, means for sequentially selecting display pixels of a display layer of the display medium, and collectively modulating the temperature of the high-molecular liquid crystalline compound of each display layer corresponding to the selected display pixel. Thus, the display device is provided with control means for independently controlling the optical density of each display layer for each display layer.

 Hereinafter, the present invention will be described in detail.

FIG. 1 is an explanatory diagram showing an example of the display medium of the present invention. In the figure, a display medium A of the present invention is provided with a light absorbing layer 2 on a substrate 1 and a first alignment layer H ₁ on the light absorbing layer 2.
And the first display layer D ₁ , the second alignment layer H ₂ and the second display layer D ₂ ,
... An n-th alignment layer Hn, an n-th display layer Dn, and an (n + 1) -th alignment layer Hn + 1 are sequentially provided, and a surface protective layer 3 is laminated on the (n + 1) -th alignment layer Hn + 1. Each liquid crystal compound constituting the display layer has a different glass transition temperature and phase transition temperature, and the temperature range from the glass transition temperature to the phase transition temperature of the polymer liquid crystal compound of each display layer overlaps each other. It is configured not to do so.

The polymer liquid crystalline compound that can be used in the present invention is a thermotropic main chain type / side chain type polymer liquid crystalline compound and contains a nematic phase, a smectic phase, a chiral nematic phase, and a chiral smectic phase. The temperature range is preferably from 0 ° C to 300 ° C. 0 ° C
If the temperature is lower than 300 ° C., it is difficult to control the temperature. Further, having a glass transition point is important for performing display with memory because the liquid crystal structure can be fixed without a holding operation.

As the polymer liquid crystal compound having a chiral nematic phase and a chiral smectic phase used in the present invention, a side chain polymer liquid crystal compound, a main chain polymer liquid crystal compound, and the like can be used. Examples of the side chain type polymer liquid crystal compound include those represented by the following formulas (1) to (12). (However, * represents an asymmetric carbon center, and n is 5 to 1000) The main chain type polymer liquid crystal compound includes an ester bond, an amide bond, a peptide bond, a urethane bond, a mesogen group, a flexible chain and an optically active group.
It is polymerized by an ether bond or the like. More preferably, an ester bond is used.

Specific compounds that can be used as the mesogen group include terphenyldicarboxylic acid, P-terephthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, stillbenzylbenzylcarboxylic acid, azobenzenedicarboxylic acid, azoxybenzenedicarboxylic acid, and cyclohexanedicarboxylic acid. Acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, biphenyl ethane dicarboxylic acid, dicarboxylic acid such as carboxycinnamic acid, hydroquinone, dihydroxy biphenyl, dihydroxy terphenyl, dihydroxy azobenzene, dihydroxy azoxybenzene, dihydroxy Dimethylazobenzene, dihydroxydimethylazoxybenzene, dihydroxypyridazine, dihydroxynaphthalene, dihydroxyphenyl Ether, bis (hydroxyphenoxy) and diols such as ethane, hydroxy benzoic acid, hydroxy biphenyl carboxylic acid, hydroxy terphenyl carboxylic acid, hydroxy cinnamic acid,
Hydroxycarboxylic acids such as hydroxyazobenzenecarboxylic acid, hydroxyazoxybenzenecarboxylic acid, and hydroxystilbenecarboxylic acid can be used.

Raw materials for the flexible chain include methylene glycol, ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, dodecanediol,
Diols such as tridecanediol, tetradecanediol, pentadecadiol, diethylene glycol, triethylene glycol, tetraethylene glycol, nonaethylene glycol, and tridecaethylene glycol;
Dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid can be used.

As the optically active group, a bifunctional one is desirable. Specifically, (+)-3-methyl-1,6-hexanediol (-)-3-methyl-1,6-hexanediol (+)-3-methyladipacid (-)-3-methyl Adipic acid (D) -mannitol (D-mannitol) (L) -mannitol (L-mannitol) (+)-pantothenic acid (+)-1,2-4-trihydroxy-3,3-dimethylbutane (- ) -1,2-Propanediol (+)-1,2-propanediol (+)-lactic acid (−)-lactic acid (2S, 5S) -2-methyl-3-oxahexane-1,5-diol (2S , 5S, 8S) -2,5-dimethyl-3,6-dioxanonane-
1,8-Diol The above-mentioned mesogen group, flexible chain and optically active group are polycondensed to obtain the polymer liquid crystalline compound having an asymmetric carbon of the present invention. At this time, the use of a catalyst can improve the degree of polymerization and reduce impurities due to side reactions and the like, but it is desirable to remove the polycondensation by reprecipitation after completion of the polycondensation.

Specific examples include compounds represented by the following formulas (13) to (25). The polymer referred to in the present invention refers to a main chain type having n ₂ of 5 or more as shown below. (Hereinafter, n ₂ = 5 to 1000) Further, examples of the polymer liquid crystal compound having a nematic phase and a smectic phase used in the present invention include a side chain polymer liquid crystal compound and a main chain polymer liquid crystal compound.

Since these do not have an optically active group, they do not show a helical structure, but can be used effectively by being combined with a polymer liquid crystalline compound having the optically active group.

Specific examples include those represented by the following formulas (26) to (34).

In the present invention, a polymer liquid crystal composition composed of the polymer liquid crystal compound and a low-molecular liquid crystal compound can be used. It can be obtained by mixing the molecular liquid crystalline compound in a predetermined ratio, and dissolving by heating or dissolving in a common solvent.

Next, the low-molecular liquid crystal compound may be any compound that is compatible with the high-molecular liquid crystal compound, and more preferably a compound having an asymmetric carbon center. Specific examples include chiral low-molecular liquid crystal compounds represented by the following formulas (35) to (49), but are not limited thereto.

In addition to the above, various polymer liquid crystal compounds can be used, and for example, discotic polymer liquid crystals and thermotropic liquid crystalline glutamate copolymers can also be used.

In the high-molecular liquid crystal composition obtained by blending the high-molecular liquid crystal compound and the low-molecular liquid crystal compound as described above, the content of the high-molecular liquid crystal compound is 50% by weight or more, preferably 70% by weight or more.
It is desirable that the content be not less than% by weight. If it is less than 50% by weight, the helical structure cannot be fixed sufficiently.

In addition, in order to display a color image, a high-quality liquid crystal composition can be displayed well by adding a dichroic dye and using the dichroism.

When the heating means is a laser beam, it is effective to add a light absorber according to the wavelength of the laser beam.

The polymer liquid crystal compound obtained as described above and the polymer liquid crystal composition obtained from the polymer liquid crystal compound,
It may be used alone as a film or laminated on a supporting substrate (hereinafter, referred to as a substrate).

In the present invention, as a substrate that can be used, glass,
Any material such as plastic or metal can be used, and if necessary, a transparent electrode such as an ITO film or a patterned electrode may be formed and used on these substrates.

In addition, as a method of coating or forming a thin film on the substrate, a liquid state by heating and melting, or by dissolving in a solvent, spin coating method, casting method,
It can be performed by a dipping method, a bar coating method, a roll coating method, a gravure coating method, a doctor blade method, or the like.

In order to apply a polymer liquid crystalline compound with a different helix structure period in a mosaic or stripe shape,
Use of a screen printing method or the like, patterning using a photoresist, or the like is suitable.

In the present invention, a display medium can be obtained by repeating the above steps and laminating two or more polymer liquid crystalline compounds having different glass transition points and phase transition temperatures as display layers.

In this case, an alignment layer, an electrode, a heat insulating layer, a light absorbing layer, and the like may be provided between display layers made of a polymer liquid crystal compound.

In the display medium of the present invention, when the high-molecular liquid crystalline compound has a chiral nematic phase, it is desirable to perform a horizontal alignment treatment.

Examples of the horizontal orientation treatment include stretching by mechanical force, roll stretching, shearing, electric and magnetic fields, and interface control. When a substrate is used, a horizontal alignment treatment by interface control is particularly preferred.

More specific horizontal alignment processing by controlling the interface is as follows.

Rubbing method By a solution coating method or evaporation or sputtering on a substrate, for example, silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron Inorganic insulating materials such as nitrides, polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylerin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin and acrylic resin An orientation control film formed by using an organic insulating material such as an organic insulating material can be provided.

This orientation control film is formed by coating the above-mentioned inorganic insulating material or organic insulating material, and then rubbed (rubbed) in one direction with velvet, cloth or paper.

Oblique evaporation An oxide such as SiO or a fluoride or a metal such as Au or Al and an oxide thereof are deposited from an oblique angle of the substrate.

The organic or inorganic insulating film shown by the oblique etching method is etched by irradiating an ion beam or oxygen plasma obliquely.

Use of stretched polymer film A film obtained by stretching a polymer film such as polyester or polyvinyl alcohol also shows good orientation.

Grating method The N liquid crystal is also oriented in the groove direction by forming a groove on the substrate surface by using photolithography, stamper, or injection.

In the display medium of the present invention, when the high-molecular liquid crystalline compound has a chiral smectic phase, it is desirable to perform a vertical alignment treatment.

The vertical alignment treatment includes stretching by mechanical force, roll stretching, shearing, electric and magnetic fields, and interface control. When a substrate is used, vertical alignment treatment by controlling the interface is particularly preferable.

As a more specific interface control, there is the following vertical alignment treatment.

Form between vertical alignments.

A vertically oriented layer such as organosilane, lecithin or PTFE is formed on the substrate surface.

Oblique deposition The vertical orientation can be given by appropriately selecting the deposition angle while rotating the substrate by the oblique deposition method.
Further, after oblique deposition, a vertical alignment agent shown by may be applied.

In the alignment treatment, various alignment means may be used alone or in combination of two or more means.

The display medium of the present invention which has been subjected to the orientation treatment can efficiently perform selective scattering by its helical structure, and can perform color display by selecting the period of the helical structure. Specifically, one that performs color display using the temperature change of the period of the helical structure, one that uses the phase transition due to heat of the polymer liquid crystalline compound, one that changes the period of the helical structure using the electric field response, etc. There is. At this time, if the temperature is equal to or lower than the glass transition point of the liquid crystalline polymer compound, the image is retained and there is no need to repeatedly write.

The display medium of the present invention can be provided with a protective film on the surface, and when writing and erasing is performed by a heating element head or the like, it is preferable that the medium does not undergo thermal deterioration or thermal deformation.

Further, by providing the light absorbing layer, light other than the selective scattering can be absorbed, and the contrast can be improved.

Next, a description will be given of a display method for independently controlling the optical density of each layer of the display layer made of the polymer liquid crystalline compound in the display medium of the present invention.

FIG. 1 shows a layer configuration in which n display layers are stacked. The glass transition temperature of the n-th layer is TGn, and the liquid crystal phase transition temperature is T.
Cn. Assuming that the temperature given by the heating element head or the like is TAn or TAn-1, TGn, TCn, and TAn have the following relationship.

TAn>TCn> TGn ≧ TAn-1 In this case, the n display layers may be sequentially stacked,
They may be randomly stacked.

At this time, when the n-th display layer is selected, TAn-
By heating and rapidly cooling the display pixel to 1, only the n-th layer shows the liquid crystal layer, the other layers are fixed to the amorphous layer, and light is absorbed by the light absorbing layer. Next, the n-
To select one layer, heat to TAn, rapidly cool to TCn, and slowly cool from TCn to TGn. Next, only the (n-1) th layer is fixed by the liquid crystal layer by rapidly cooling from TGn.

Hereinafter, a display medium having three display layers will be described as a typical example. The three display layers include a display layer having selective scattering at about 650 nm (hereinafter referred to as a layer), a display layer having selective scattering at about 550 nm (hereinafter referred to as a layer), and a display layer having selective scattering at about 450 nm (hereinafter referred to as a layer). has the respective glass transition temperature TG, TG, TG, a liquid crystal phase transition temperature TC, TC, and TC, respectively, the temperature applied to the display layer in the heating element head, etc. TA _1, TA _2, TA ₃ When the relations are as follows,
FIG. 2 shows a temperature control pattern for individually selecting or erasing layers and layers.

TA ₃ >TC> TG ≧ TA ₂ >TC> TG ≧ TA ₁ >TC> TG By controlling the heating temperature and the cooling rate as described above, each display layer can be selected and erased.

In addition, since the optical density can be continuously changed by controlling the degree of liquid crystallinity by controlling the heating temperature, the holding time, and the cooling rate, R, G, B
Can be displayed in gradation and full-color high-definition image display without color shift or the like can be performed.

In the selection of each display layer by the temperature modulation, the control of the temperature distribution by the heat conduction is used in combination, so that more efficient control can be performed.

In the method using laser light, it is preferable to control the temperature by controlling the concentration of the light absorbing agent added to each display layer made of a polymer liquid crystalline compound.

In the present invention, as shown in FIG. 5, two or more heating means, for example, a heating element head 4 are provided in a direction in which recording / erasing is sequentially performed on the display medium A, and the heating means is provided for each pixel of the display layer. Are sequentially selected to modulate the temperature of the high-molecular liquid crystalline compound, whereby the optical density of each display layer can be independently controlled for each pixel.

Further, as shown in FIG. 6, the heating element head used in the present invention may be a heating element head composed of a plurality of divided heating element heads 4a.

The display device used in the display method described above includes at least the display medium, means for sequentially selecting display pixels on a display layer of the display medium, and two or more heating element heads in a direction in which recording and erasing are sequentially performed on the display medium. It is preferable to provide a heating means having the following.

According to the present invention, a polymer liquid crystalline compound having a different glass transition temperature and a different phase transition temperature is laminated as a display layer, and a phase is determined from the glass transition temperature of the polymer liquid crystal compound of each display layer. In a display medium in which the temperature range up to the transition temperature does not overlap, by modulating the temperature of the high-molecular liquid crystalline compound, the optical density of each display layer can be independently controlled for each display layer. Accordingly, full-color display can be performed for each pixel of the display medium, and a high-definition color image display of, for example, 12 pel or more without color shift can be performed.

Further, when the high-molecular liquid crystal compound has a helical structure and display is performed by selective scattering based on the period of the helical structure, the period of the helical structure of the high-molecular liquid crystal compound in each display layer is set to red (R). . Green (G). By corresponding to the three primary colors of blue (B), display with good color purity and good contrast can be performed. At this time, since the main axis of the spiral structure is perpendicular to the display surface of the display layer, the efficiency of selective scattering is further improved.

[Example] Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 A display medium having the configuration shown in FIG. 3 was produced. First, a dichloroethane solution of a polymer liquid crystal having a structure represented by the following formula (I) is applied to a glass substrate 1 having a polyimide alignment film that has been subjected to a uniaxial rubbing treatment, dried, and dried to a display layer (I layer) having a thickness of about 10 μm. the formation of the D _1. Next, an aqueous solution of polyvinyl alcohol (PVA) is applied and dried to form a separation membrane 8 having a thickness of about 0.5 μm, and then a dichloroethane solution of a polymer liquid crystal having a structure represented by the following formula (II) is applied thereon. , dried display layer having a thickness of about 10 [mu] m (II layer) was formed D _2. These are the I layer and the II layer, respectively.

View more layer (II layer) was laminated PI film having a thickness of 10μm as a heat-resistant surface protective layer 3 on the D _2.

Next, a recording method applied to this display medium will be described with reference to FIG.

In order to select the I layer, the display pixels are heated by the heating element head 4 which is installed so as to be movable by the head moving device 7 and connected to the heating element temperature control device 6, and is heated to 290 ° C.
The heating element head 4 was turned off, and was rapidly cooled to 100 ° C. next,
By slowly cooling from 100 ° C. to room temperature by the heating element head 4, a red display was obtained.

Next, in order to select the layer II, the display pixels were heated by the heating element head 4 and maintained at 270 ° C., and then rapidly cooled to room temperature, whereby a green display was obtained.

Example 2 An infrared absorber (Nippon Kayaku Co., Ltd.) was added to a glass substrate having a rubbed polyimide alignment film, in a dichloroethane solution of a polymer liquid crystal represented by the following formula (III) at a ratio of 1 wt% to the polymer liquid crystal. Co., Ltd., IR-750) was applied and dried to obtain a display layer having a thickness of about 10 μm. A polyimide film having a thickness of about 10 μm is laminated thereon, and further, an infrared absorbing agent (manufactured by Nippon Kayaku Co., Ltd.) is added to a dichloroethane solution of a polymer liquid crystal represented by the following formula (IV) at a ratio of 1 wt% to the polymer liquid crystal. , IR-750), and dried to obtain a display layer having a thickness of about 20 μm.

In this state, the mixture was kept at 90 ° C. for 5 hours and observed with a polarizing microscope. As a result, an SmC ^* phase was observed. A polyimide film having a thickness of about 10 μm is further laminated on the display layer of this substrate, and further added to a dichloroethane solution of a polymer liquid crystal represented by the following formula (V) at a ratio of 1% by weight to the polymer liquid crystal with an infrared absorber ( Nippon Kayaku Co., Ltd., IR-750) was applied, dried, and a display layer having a thickness of about 10 μm was laminated to obtain a display medium.

Next, a method of recording on the display medium by using a laser will be described with reference to FIG. A laser light having a wavelength of 780 nm generated by a semiconductor laser light source 9 connected to a laser driving device 13 is applied to a display medium A through a collimator lens 10 and a condenser (objective) lens 11. After irradiating with an output of 10 mW, once turned off and then irradiating with 1 mW, (II
I) Only the display layer containing the liquid crystalline polymer compound represented by the formula was recorded.

Next, irradiation was performed at 10 mW, the power was gradually reduced to 8 mW, and the device was turned off. As a result, only the display layer containing the liquid crystalline polymer compound represented by the formula (V) was recorded. Next, 10
After irradiating with mW, turn off once, then irradiate with 5mW and turn off
As a result, only the display layer containing the liquid crystalline polymer compound represented by the formula (IV) was recorded.

[Effects of the Invention] As described above, according to the display medium, the display method, and the apparatus of the present invention, each display layer of the display medium having a multilayer display layer containing a high-molecular liquid crystal compound is independently formed. Single or multiple selection is now possible. As a result, the color and density can be controlled for each pixel, so that a full-color high-definition image display without color shift or the like can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a display medium of the present invention, FIG. 2 is a graph showing an example of a temperature control pattern for independently selecting or independently erasing a display layer of the display medium, and FIG. FIG. 4 is an explanatory view showing a display method of a display medium of Example 1, FIG. 4 is an explanatory view showing a display method of a display medium of Example 2, FIG. 5 is an explanatory view showing another example of a display method of a display medium, and FIG. 6
The figure is an explanatory view showing an example of the heating element head. DESCRIPTION OF SYMBOLS 1 ... Substrate 2, ... Light absorption layer 3 ... Surface protective layer 4, ... Heating element head 4a ... Divided heating element head 5 ... High molecular liquid crystal compound 6 ... Heating element temperature control device 7 ... Head moving device 8 Separation membrane 9 Laser light source 10 Collimator lens 11 Condensing lens 12 Lens driving device 13 Laser driving device D _{1 to} D _n Display layer H ₁ to H _{n + 1} …… Alignment layer A …… Display medium

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-111514 (JP, A) JP-A-61-179417 (JP, A) JP-A-62-14114 (JP, A)

Claims (16)

(57) [Claims] 1. A display medium comprising a polymer liquid crystal compound having different glass transition temperatures and phase transition temperatures, each of which is laminated as a display layer, wherein a phase transition is performed from the glass transition temperature of the polymer liquid crystal compound in each display layer. A display medium characterized in that the temperature ranges up to the temperature do not overlap. 2. The display medium according to claim 1, wherein each of said display layers is made of a high-molecular liquid crystalline compound having a helical structure having different periods. 3. The display medium according to claim 2, wherein said high-molecular liquid crystalline compound having a helical structure has a chiral nematic phase. 4. The display medium according to claim 2, wherein the high-molecular liquid crystalline compound having a helical structure has a chiral smectic phase. 5. The display medium according to claim 1, wherein the display medium does not have an electrode for driving a display layer made of the high-molecular liquid crystalline compound. 6. The display medium according to claim 1, wherein only an alignment layer exists between said display layers. 7. The display medium according to claim 1, wherein each of said display layers scatters light in a different wavelength range. 8. A polymer liquid crystalline compound having different glass transition temperatures and phase transition temperatures, each being laminated as a display layer, and a temperature from the glass transition temperature to the phase transition temperature of the polymer liquid crystalline compound in each display layer. In a display medium in which the ranges do not overlap, the optical density of each display layer is controlled independently for each display layer by collectively modulating the temperature of the polymer liquid crystalline compound of each display layer. Display method to be used. 9. The display method according to claim 8, wherein the means for modulating the temperature is a heating element head. 10. The display method according to claim 8, wherein the means for modulating the temperature is a laser beam. 11. The display method according to claim 8, wherein the optical density of each of the display layers is controlled without applying an electric field to the high-molecular liquid crystalline compound. 12. Each of the display layers is a display layer that scatters light in a different wavelength region, and color display is performed by controlling the optical density of each display layer independently for each display layer. The display method according to claim 8, wherein 13. A polymer liquid crystalline compound having different glass transition temperatures and phase transition temperatures, each being laminated as a display layer, and a temperature from the glass transition temperature to the phase transition temperature of the polymer liquid crystalline compound in each display layer. In a display medium whose ranges do not overlap, two or more heating means are provided in the direction in which recording and erasing are sequentially performed on the display medium, and the heating means sequentially selects each pixel of the display layer, and corresponds to the selected pixel. A display method, wherein the optical density of each display layer is independently controlled for each pixel by collectively modulating the temperature of the polymer liquid crystalline compound of each display layer. 14. The display method according to claim 13, wherein said heating means is a heating element head. 15. A polymer liquid crystalline compound having different glass transition temperatures and phase transition temperatures, each of which is laminated as a display layer, and a temperature from the glass transition temperature to the phase transition temperature of the polymer liquid crystalline compound in each display layer. The display device includes a display medium whose ranges do not overlap, a means for sequentially selecting display pixels of a display layer of the display medium, and a heating means having two or more heating element heads in a direction in which recording / erasing on the display medium is sequentially performed. A display device characterized by the above-mentioned. 16. A polymer liquid crystalline compound having different glass transition temperatures and phase transition temperatures each laminated as a display layer, and a temperature from the glass transition temperature to the phase transition temperature of the polymer liquid crystalline compound in each display layer. A display medium whose ranges do not overlap, means for sequentially selecting display pixels of a display layer of the display medium, and collectively modulating the temperature of the polymer liquid crystal compound of each display layer corresponding to the selected display pixel. And a control unit for independently controlling the optical density of each display layer for each display layer.