JP2003167225A - Electronic display medium and electronic display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic display medium wherein a mark can be added with other display color by handwriting and an image can be additionally written to the image on which an image of a diagram or the like is displayed and which is lightweight, thin and manufactured at low cost. <P>SOLUTION: The electronic display medium is formed by layering a first liquid crystal layer consisting of a cholesteric liquid crystal, wherein an image is recorded by the both functions of irradiation of writing Light carrying the image and application of voltage between a pair of electrodes and a second liquid crystal layer consisting of a cholesteric liquid crystal, wherein a pressed part is compressed by pressing so as to be freely restored to make the internal liquid crystal flow and the trace of the pressed part is recorded by the flowing function of the liquid crystal between the pair of electrodes. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display medium capable of displaying both an image and a handwritten image. The present invention includes a display, a printer, a facsimile, a copying machine,
It can be used for electronic newspapers, electronic books, electronic blackboards, etc.

[0002]

2. Description of the Related Art Conventionally, a C such as a personal computer is used.
BACKGROUND ART While displaying an arbitrary image on a display unit such as RT or LCD, an image manually input using a handwriting input unit such as a digitizer or a tablet is displayed at the same time. In such a case, since the handwriting locus input from the handwriting input means is converted into position information and input to the display means for display, the processing device that executes them and the drive power supply for the processing device are executed. And are needed.

In Japanese Unexamined Patent Publication No. 6-301464, light is emitted from an input means and a voltage is applied to an input device in which a single cholesteric liquid crystal layer and a photoconductive layer are laminated between a pair of simple matrix electrodes. Thus, a technique for displaying an image is disclosed. The cholesteric liquid crystal of this input device becomes a white turbid state due to its dynamic scattering effect when an AC voltage of 100 Hz or less is applied, and becomes several hundred Hz.
When the above AC voltage is applied, the liquid crystal molecules are aligned in the direction of the applied electric field, so that the liquid crystal molecules become transparent and have a memory property. Therefore, after applying an AC voltage of several hundred Hz or more in advance to make the display transparent and erasing the display, the photoconductive layer is locally irradiated with light with a light pen while applying an AC voltage of 100 Hz or less. When the photoconductive layer is irradiated with light, the impedance of the photoconductive layer decreases, the partial pressure of the liquid crystal layer rises, and the orientation of the liquid crystal molecules transits to a cloudy state.
Display by handwriting can be realized. Further, an arbitrary image can be displayed by applying a voltage line-sequentially to the simple matrix type electrode.

Japanese Patent Laid-Open No. 2000-127683 discloses that
Disclosed is an electronic blackboard device in which a polymer stabilized cholesteric texture (PSCT) liquid crystal is laminated between a pair of simple matrix type electrodes, and an image displayed on a display unit can be partially erased freely. There is.
Since the PSCT liquid crystal has a property that the display changes from a dark state to a bright state due to the flow orientation due to pressing when transmitting light in a state where no voltage is applied, the PSCT liquid crystal is changed to a bright state by pressing the display panel surface with a pen. A locus can be left, and an arbitrary image can be displayed by applying a voltage to the simple matrix type electrodes line-sequentially.

[0005]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
When the electronic blackboard device disclosed in Japanese Patent Laid-Open No. 000-127683 is used in, for example, a meeting, an image such as a chart is displayed and a mark is added by handwriting, or an image is additionally written, or the image is displayed. It is often the case that it is desired to change the color of the display of the highlighted portion and the portion additionally written by handwriting, but it is difficult to deal with them because the disclosed electronic blackboard device has only a single display layer.
Further, the connection pitch of the simple matrix electrodes used for displaying an arbitrary image with the drive circuit is as narrow as several lines / mm, and it is necessary to surely connect at cross points ranging from hundreds to thousands. Therefore, it is difficult to detachably configure the drive circuit, and there is a problem that the device as a whole is heavy and thick, and the cost is high.

In view of the above circumstances, the present invention is a light-weight device capable of displaying an image such as a chart and the like, adding a mark by handwriting with another display color, and additionally writing an image.
An object is to provide a thin and low-cost electronic display medium.

[0007]

An electronic display medium of the present invention which achieves the above object is provided with a writing light for carrying an image between a pair of electrodes, and a voltage application between the pair of electrodes. The first liquid crystal layer made of cholesteric liquid crystal in which an image is recorded by both of the actions of and, and the internal region of the liquid crystal is fluidized by compressing the pressed region so that the pressed region is recoverable by the pressure, and the locus of the pressed region is generated by the flow action of the liquid crystal. It is characterized by being laminated with a second liquid crystal layer made of cholesteric liquid crystal to be recorded.

Here, the first and second liquid crystal layers are
It is preferable that they have different selective reflection wavelength ranges from each other.

Further, it is preferable that a photoconductive layer which absorbs light and changes in resistance value is laminated between the pair of electrodes.

Further, the second liquid crystal layer has a higher phase transition voltage for phase transition from the cholesteric liquid crystal phase to the nematic liquid crystal phase than the first liquid crystal layer, and the second liquid crystal layer between the pair of electrodes has a higher phase transition voltage. By the application of the voltage when an image is recorded on the first liquid crystal layer due to the effects of both the irradiation of the writing light carrying the image on the first liquid crystal layer and the application of the voltage between the pair of electrodes. It is also a preferable aspect that the locus of the pressed portion is erased.

The image writing apparatus of the present invention which achieves the above-mentioned object is realized by both the irradiation of the writing light for carrying an image and the application of the voltage between the pair of electrodes between the pair of electrodes. A first liquid crystal layer made of cholesteric liquid crystal on which an image is recorded, and a pressed portion is recoverably compressed by pressing to flow the liquid crystal inside, and a trajectory of the pressed portion is recorded by the flow action of the liquid crystal. Voltage applying means for applying a voltage between the pair of electrodes of an electronic display medium formed by laminating a second liquid crystal layer made of liquid crystal, and writing for irradiating the electronic display medium with writing light for carrying an image. By adjusting the light irradiation means, the voltage application means, and the writing light irradiation means, an image is recorded on the first liquid crystal layer, and the locus of the pressed portion is recorded on the second liquid crystal layer. Erase the locus when Image of the first liquid crystal layer is characterized in that a control means for the state in which the trajectory of the pressed portion is recorded a liquid crystal layer of the second through flow action of the liquid crystal as it is.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an electronic display medium and an image writing device of the present invention will be described below.

FIG. 1 is a diagram for explaining the principle of recording an image on the liquid crystal layer of the electronic display medium of this embodiment.

Characteristic curves represented by a solid line and a dotted line in FIG. 1 represent voltage-reflectance characteristics measured after applying a voltage to the cholesteric liquid crystal layer and releasing the voltage, and the vertical axis represents the reflectance of the cholesteric liquid crystal layer. , The horizontal axis represents voltage.

The solid line A in the figure represents the case where the initial orientation is the planar orientation (P orientation), and the dotted line B represents the case where the initial orientation is the focal conic orientation (F orientation).

Here, the cholesteric liquid crystal has an optical activity,
Although any property such as birefringence and light absorption can be used as the display mode, the display mode using selective reflection of light is particularly preferably used because the display color can be easily adjusted. It Cholesteric liquid crystals have a helical molecular orientation, and in a planar orientation (P orientation) in which the helix axis is substantially parallel to the substrate normal line, color is produced by selectively reflecting incident light, and the helix axis is almost the substrate normal line. Since the incident light is transmitted in the vertical focal conic alignment (F alignment), the light is colored in the color of the light shielding layer that shields the incident light (for example, black if the light shielding layer is black).

In the figure, when the applied voltage is V1 or less, the molecular orientation of the cholesteric liquid crystal does not change, so that a so-called dead zone is formed in which the reflectance does not change regardless of the initial orientation. When the applied voltage is V2 or more and V3 or less, the F orientation becomes stable and light is transmitted to provide a dark display. When the applied voltage is V4 or more, the P orientation becomes stable and bright display is obtained. It should be noted that V4 corresponds to a threshold voltage at which the cholesteric liquid crystal phase makes a phase transition to the nematic liquid crystal phase.

For example, by applying a voltage that changes the partial pressure of the liquid crystal layer across the range of V3 to V4 by irradiating the writing light carrying an image, or after resetting to the P orientation in advance, the writing light is irradiated. The reflectance of the cholesteric liquid crystal layer can be controlled by applying a voltage that changes the partial pressure of the liquid crystal layer across the range of V1 to V2 by irradiation.

In such control, the electrodes 2a and 2b are
(1) line-sequential scanning as a simple matrix type,
(2) Thin film transistors, thin film diodes, MIM (M
An active matrix driving method such as an et al-insulator-metal) element may be used,
Alternatively, a method of laminating the liquid crystal layer and the photoconductive layer as described above (3) and applying a voltage between the electrodes while irradiating the photoconductive layer with a photoimage may be used.

FIG. 2 is a schematic diagram showing the image writing apparatus of this embodiment. In FIG. 2, the image writing device is an electronic display medium in which a fluid liquid crystal layer 3b, a non-fluid liquid crystal layer 3a, a photoconductive layer 5, and a light-shielding layer 4 are laminated between a pair of electrodes 2a and 2b. This corresponds to the embodiment of the display medium.) 3
0 is arranged at a predetermined writing position, and the voltage applying means 20 which can be detachably connected to a pair of electrodes of the arranged electronic display medium to apply a voltage to the arranged electronic display medium. It is composed of a writing light irradiating means 25 for irradiating the writing light carrying an image, and a control means 15 for adjusting the voltage applying means and the writing light irradiating means. Also,
In addition, a handwriting means 10 for writing an image on the electronic display medium by handwriting is provided.

Here, the handwriting means 10 does not need to use a special one, and when the electronic display medium 30 is pressed, the pressed portion is recoverably compressed and the liquid crystal inside flows, and the liquid crystal flows. It is sufficient that the locus of the pressed portion is recorded, and for example, it may be a mechanical pencil without a core or a fingertip.

When the image is recorded on the electronic display medium 30 by irradiating the image-bearing light, the side of the electronic display medium 30 where the photoconductive layer 5 is laminated is irradiated with the writing light W. The pair of electrodes 2a and 2b of the electronic display medium 30 is connected to the voltage applying unit 20. The control unit 15 uses the writing light irradiation unit 2
While irradiating the writing light W carrying an image from 5,
When a predetermined voltage is applied from the voltage applying means 20 to record an image of X color on the non-fluidic liquid crystal layer 3a and the trajectory of the pressed portion due to the pressing is recorded on the liquid crystal layer 3b. , Erase that locus. In that state, even if the pair of electrodes 2a and 2b of the electronic display medium 30 are removed from the voltage applying means 20, the X-color image recorded in the non-fluid liquid crystal layer 3a remains as it is due to the memory property of the liquid crystal. Retained.

For the non-fluidic liquid crystal layer 3a, the voltage applied by the control means 15 from the voltage applying means 20 is a function of both the irradiation of the writing light W carrying an image and the application of the voltage, and thus the cholesteric effect. The size is such that an image based on the phase transition from the liquid crystal phase to the nematic liquid crystal phase is recorded, and at the same time, for the fluid liquid crystal layer 3b, the track of the pressed portion recorded by the pressing by the handwriting means 10 is erased. Is set to

When it is desired to add characters or marks in Y color to the electronic display medium, the handwriting means 10 is applied from the substrate on the side where the liquid crystal layer 3b of the electronic display medium is laminated.
By handwriting the character or mark, the locus of the pressed portion due to the pressing is recorded in Y color.

Here, in this embodiment, the photoconductive layer 5 is laminated on the electronic display medium, and the action of the photoconductive layer 5 causes the voltage distributed to the non-fluidic liquid crystal layer 3a according to the writing light W. However, the non-fluidic liquid crystal layer 3a is formed by forming the electrodes 3a and 3b into a simple matrix type and performing line-sequential scanning or active matrix driving without laminating the photoconductive layer 5. An image may be recorded on the non-fluidic liquid crystal layer 3a by applying a distributed voltage to the.

Next, the electronic display medium used in this embodiment will be described.

In the electronic display medium 30, the pressed portion is reversibly compressed by pressing between the transparent electrode 2a formed on the transparent substrate 1a and the transparent electrode 2b formed on the transparent substrate 1b. Then, the liquid crystal in the inside flows and the locus of the pressed portion is recorded by the flow action of the liquid crystal. The liquid crystal layer 3b made of cholesteric liquid crystal is irradiated with the writing light for carrying the image and the voltage is applied between the electrodes. An image is recorded by the action of both and, composed of cholesteric liquid crystal,
The non-fluidic liquid crystal layer 3 in which the liquid crystal inside does not flow when pressed.
a and a photoconductive layer 5 whose resistance value changes by absorbing light are stacked, and the light transmitted through the liquid crystal layer 3 does not reach the photoconductive layer 5 between the photoconductive layer 5 and the electrode 2b. Thus, the light shielding layer 4 for shielding light is laminated.

When a predetermined voltage is applied between the electrode 2a and the electrode 2b, the divided voltage is applied to each of the liquid crystal layers 3a and 3b, the light shielding layer 4, and the photoconductive layer 5.
When the photoconductive layer 5 is irradiated with the writing light W while a predetermined voltage is applied, the resistance value of the photoconductive layer 5 changes according to the intensity distribution of the writing light W, thereby causing non-flow. Liquid crystal layer 3
A voltage distribution occurs in a and the liquid crystal molecule orientation of the non-fluidic liquid crystal layer 3a changes accordingly. This change in the molecular orientation changes the optical characteristics of the liquid crystal layer 3a such as transmittance, absorptance, and reflectance, so that an image can be written in the liquid crystal layer 3a of the electronic display medium 30. At the same time, the voltage is set so that all the molecular orientations of the fluid liquid crystal layer 3b are changed to a state of transmitting light, so that the trace of the pressed portion written by handwriting is erased.

When read light R is incident on the non-fluidic liquid crystal layer 3a for reading an image recorded on the non-fluidic liquid crystal layer 3a, the resistance value is reached when the read light R reaches the photoconductive layer 5. Fluctuates and adversely affects the behavior of the non-fluidic liquid crystal layer 3a. Therefore, the light-shielding layer 4 that shields the reading light R is provided between the non-fluidic liquid crystal layer 3a and the photoconductive layer 5.

The fluid liquid crystal layer 3b is constructed so that the pressed portion is reversibly compressed by pressing and the liquid crystal inside flows. Since the liquid crystal itself originally has liquidity, the liquidity can be easily ensured unless this is impeded. However, if the fluidity is too high, when the electronic display medium 30 is bent, flow orientation may occur over a wide area, or a handwritten trajectory may become too thick.
It is preferable to appropriately suppress the fluidity by using a high-viscosity liquid crystal material or by compounding a liquid crystal as a continuous phase in a polymer matrix in a range that does not hinder the electrical response.

Regarding the stacking order of the liquid crystal layers 3a and 3b, it is preferable to stack the fluid liquid crystal layer 3b which causes flow orientation on the substrate 1a side which is deformed by pressing. Since it is necessary to quickly restore the thickness of the liquid crystal layer 3 after removing the pressure, it is preferable to insert the spacer 11 made of a resin or an inorganic material in the fluid liquid crystal layer 3b.

On the other hand, the non-fluidic liquid crystal layer 3a can be realized by providing a partition for preventing liquid crystal from flowing in the layer.

For example, 1) microencapsulated liquid crystal,
2) Dry film of liquid crystal emulsion (so-called NCAP liquid crystal), 3) Polymer dispersion in which liquid crystal droplets are island-like isolated by phase separation methods such as optical phase separation method, solvent phase separation method and thermal phase separation method. A liquid crystal, 4) a liquid crystal injected by forming partition walls of a resin or an inorganic material by a printing method or a lithography method, or the like can be used. The effect is further enhanced by using a liquid crystal material having an appropriately high viscosity within a range that does not hinder the electrical response. Further, for the purpose of preventing liquid crystal mixing between the non-fluidic liquid crystal layer 3a and the liquid crystal layer 3b, an isolation film made of resin or the like may be provided between them.

The cholesteric liquid crystal has a selective reflection wavelength
Not only those belonging to the visible light wavelength range (400 to 800 nm) but also those belonging to the near infrared light wavelength range, and to be applied as a scattering-transmission type cholesteric liquid crystal display device configured using them You can Since the specific selective reflection wavelength is given by the product of the average refractive index and the spiral pitch, it is possible to control the selective reflection wavelength to an arbitrary wavelength by setting the spiral pitch to an appropriate length. Also,
In order to exhibit the memory property, the layer thickness of the liquid crystal layer 3 needs to be equal to or more than twice the spiral pitch. Therefore, the layer is formed so as to obtain a desired reflectance when bright display is performed at a desired selective reflection wavelength. Set the thickness. This layer thickness is usually in the range of several μm to several tens of μm.

In this embodiment, the fluid liquid crystal layer 3b and the non-fluid liquid crystal layer 3a are configured so that their selective reflection wavelengths are different from each other, but they do not necessarily have to be different and the same wavelengths are not necessarily required. You may comprise so that it may show the same color by setting it as a zone.

The liquid crystal material used for the liquid crystal layer 3 includes cyanobiphenyl type, phenylcyclohexyl type, phenylbenzoate type, cyclohexylbenzoate type, azomethine type, azobenzene type, pyrimidine type, dioxane type, cyclohexylcyclohexane type, stilbene type,
A known nematic liquid crystal composition such as a tolan compound to which a chiral agent composed of a cholesterol derivative or an optically active compound such as a 2-methylbutyl group is added can be used.
The liquid crystal composition itself may be an optically active compound. Further, additives such as dyes and fine particles may be added to the above-mentioned liquid crystal material.

The cholesteric liquid crystal is dispersed in a matrix made of a polymer or an inorganic material, gelled by using a crosslinkable polymer or a hydrogen bonding gelling agent, or the like.
It may be microencapsulated. Further, it may be any of high molecular liquid crystal, medium molecular liquid crystal, low molecular liquid crystal, and a mixture thereof.

Here, the image display is realized by utilizing the selective reflectivity of the cholesteric liquid crystal.
If a cholesteric liquid crystal having a memory property is used, it is not necessary to limit to a display mode utilizing selective reflectivity, and a display mode utilizing birefringence, optical rotatory power, change in absorption coefficient, etc. may be used. Further, in order to utilize these display modes, it may be used in combination with a passive optical component such as a polarizing plate, a retardation plate, a color filter, a reflection plate, or a dichroic dye may be added to the liquid crystal.

The substrate 1a is required to have flexibility so that the fluid liquid crystal layer 3b can be locally flow-oriented by being pressed, and a transparent resin film such as polyethylene terephthalate, polycarbonate, polyether sulfone, or polyolefin. Is preferably used, and the thickness thereof is preferably several tens μm to several hundreds μm.

On the other hand, the substrate 1b may be made of a hard material, and a translucent insulator such as glass or ceramic may be used in addition to the above resin film.

The electrodes 2a and 2b are metal thin films such as Au.
ITO (Indium Tin Oxide), SnO
_{2. An} oxide conductor such as ZnO and a light-transmitting conductor such as a conductive polymer such as polypyrrole are used.

The photoconductive layer 5 includes (a) an inorganic semiconductor material; a compound semiconductor such as amorphous silicon or ZnSe or CdS; (b) an organic semiconductor material; anthracene, polyvinylcarbazole, or the like; A composite of a charge generating material that generates a charge and a charge transporting material that causes a charge transfer by an electric field; examples of the charge generating material include perylene-based, phthalocyanine-based, bisazo-based, dithiopitokelopyrrole-based, squarylium-based,
Examples of charge transport materials such as azurenium-based compounds and thiapyrylium / polycarbonate-based compounds include trinitrofluorene-based, polyvinylcarbazole-based, oxadiazole-based, pyrarizone-based, hydrazone-based, stilbene-based, triphenylamine-based and triphenylmethane-based compounds. A diamine-based compound, an ion conductive material such as polyvinyl alcohol or polyethylene oxide added with LiClO ₄ , or the like is used. Moreover, the form of the composite includes a laminate, a mixture, a microcapsule, and the like. In addition,
The layer thickness of the photoconductive layer 5 is preferably in the range of 1 μm to 100 μm.

As the light-shielding layer 4, one that absorbs the writing light W and the reading light R is used. Although it cannot be uniquely determined because it depends on the sensitivity of the photoconductive layer 5 and the intensities of the writing light W and the reading light R, the transmission optical density of the light shielding layer 4 is at least 1 or more, more preferably 2 or more. Is desirable. Further, the low electrical resistance of the layer in the direction of the light-shielding layer 4 so causing reduction in resolution, it is desirable to have at least 10 ⁸ (Ω · cm) or more resistivity. Further, in order to increase the partial voltage of the applied voltage to the liquid crystal layers 3a and 3b, it is preferable that the capacitance of the light shielding layer 4 is large, the dielectric constant is large and the layer thickness is thin.

As the material of the light-shielding layer 4, a paint in which an organic / inorganic pigment such as carbon black, aniline black, or chromium oxide is dispersed in a binder resin is used.

FIG. 3 is a schematic diagram showing the voltage-reflectance characteristic of the electronic display medium of this embodiment.

In FIG. 3, the vertical axis represents the reflectance of the liquid crystal layer,
The horizontal axis represents the voltage applied to the pair of electrodes. The solid line B in the figure indicates the voltage of the liquid crystal liquid layer 3b.
V4bf represents the reflectance characteristic, the voltage at which the cholesteric liquid crystal phase changes to the nematic liquid crystal phase is V4bf, and the voltage at which the molecular orientation changes from P orientation to F orientation is V1b to V.
The range is 2b. The dotted line A represents the voltage-reflectance characteristic of the non-fluidic liquid crystal layer 3a, the voltage at which the phase transition from the cholesteric liquid crystal phase to the nematic liquid crystal phase is V4a, and the voltage at which the molecular orientation changes from P orientation to F orientation is V1a. To V2a.

Since the cholesteric liquid crystal has the property of changing to the P orientation by the flow of the liquid crystal to give a bright display, the liquid crystal liquid layer 3b is changed to the F orientation in advance so that light can be transmitted before handwriting. It is necessary to erase the image written in the fluid liquid crystal layer 3b. Therefore, as shown in the figure, the two liquid crystal layers 3a and 3b are
If the relationship of 2b <V4a <V4b is satisfied, when a voltage in the range of V3a to V4a is applied and the non-fluid liquid crystal layer 3a is irradiated with predetermined writing light to record an image. The liquid crystal layer 3b automatically becomes a light transmitting state and the written image is erased, and the image recorded in the non-liquid crystal layer 3a is maintained as it is even if the applied voltage is removed.

Next, the liquid crystal layer 3b is formed by handwriting input means.
When is pressed, the liquid crystal flows in the pressed portion to be in the P orientation and the locus of the handwritten portion is recorded, but the image recorded in the non-fluid liquid crystal layer 3a is maintained as it is.
Further, the locus recorded on the liquid crystal layer 3b is retained as it is even when the pressing is stopped.

Here, the phase transition electric field Ecn from the cholesteric liquid crystal phase to the nematic liquid crystal phase is Ecn = (π ² /
p) · √ (K ₂₂ / ε ₀ · Δε).

However, p is the spiral pitch, K ₂₂ is the twist orientation elastic coefficient, ε ₀ is the vacuum permittivity, and Δε is the permittivity anisotropy.

Therefore, by adjusting K ₂₂ or Δε of the liquid crystal layers 3a and 3b respectively, V4a <V4b
Can be realized.

Next, examples of the electronic display medium will be described.

[0053]

EXAMPLE FIG. 4 is a schematic view showing a cross section of an electronic display medium of this example.

A commercially available ITO vapor-deposited PET resin film was used as the substrate 1a and the electrode 2a, and the charge generation layer 5 was formed thereon.
A photoconductive layer 5 having a three-layer structure including a, the charge transport layer 5b, and the charge generation layer 5c was formed. First, an alcohol solution of polyvinyl butyral resin in which a phthalocyanine pigment-based charge generation material is dispersed is spin-coated to form a 0.1 μm-thick charge generation layer 5a, and then a diamine-based charge transport material and a chlorobenzene solution of a polycarbonate resin are applied. To form a charge-transporting layer 5b having a thickness of 3 μm, and finally, an alcohol solution of polyvinyl butyral resin having a phthalocyanine pigment-based charge-generating material dispersed therein is spin-coated to form a charge-generating layer 5c having a thickness of 0.1 μm. Then, a photoconductive layer 5 was obtained. Then, an acrylic resin solution in which a carbon black pigment was dispersed was spin-coated to obtain a light shielding layer 4.

A cholesteric liquid crystal emulsion was applied on this with an applicator to form a non-fluid liquid crystal layer 3b having a thickness of 20 μm. As a cholesteric liquid crystal, a nematic liquid crystal MLC-6237-000 (Merck & Co., Δε =
30.8) with 1 chiral agent R811 (Merck)
A cholesteric liquid crystal having blue-green selective reflection was used by adding 4.0% and 2.5% of a chiral agent R1011 (manufactured by Merck). 1g of this cholesteric liquid crystal
Was added to 9 g of a 10% aqueous polyvinyl alcohol solution and emulsified with an internal tooth homogenizer to obtain a liquid crystal emulsion having an average particle size of 10 μm. This was applied to the photoconductive layer 5 with an applicator having a gap of 200 μm and dried by heating to obtain a non-fluidic liquid crystal layer 3b.

Next, a commercially available ITO vapor-deposited PET resin film was used as the substrate 1b and the electrode 2b, and a particle size of 20
The spherical spacers having a diameter of μm were sprayed by wet. A sealant pattern having an opening at one end was applied to the peripheral portion of the substrate with a dispenser, and was bonded to the substrate 1a through a laminator. Cholesteric liquid crystal was vacuum-injected from the opening of the sealant to obtain a fluid liquid crystal layer 3a. As a cholesteric liquid crystal for the liquid crystal layer 3a, a nematic liquid crystal MLC-6 is used.
12% of chiral agent R811 (manufactured by Merck) and 3% of chiral agent R1011 (manufactured by Merck) were added to 457-000 (manufactured by Merck, Δε = 10.2) to selectively reflect red light. A cholesteric liquid crystal was used.

The mask pattern A was projected onto the photoconductive layer 5 of the display medium thus manufactured by an LED light source having a wavelength of 650 nm as writing light, and a voltage of 400 V was applied between the electrodes 2a and 2b. As a result, a blue-green mask pattern A image was recorded on the liquid crystal layer 3b. Next, when tracing the substrate 1a with a resin stylus, a red line drawing could be obtained along the locus of the stylus.

[0058]

According to the electronic display medium of the present invention, it is possible to display an image such as a chart or the like by handwriting and additionally write, and the color of the additional display is different from that of the chart or the like. You can also Further, according to the image writing apparatus of the present invention, a multi-contact drive circuit, which is required when performing simple matrix drive, is not required when writing an image or when handwriting, and it is lightweight and portable at low cost. It is possible to provide an easily compact device. Furthermore, the electronic display medium of the present invention is thin and lightweight, has no power supply, and can be handwritten with a character or mark of a color different from the displayed image anytime, anywhere.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a display medium of the present invention and a conventional display medium.

FIG. 2 is a sectional view of a display medium of the present invention.

FIG. 3 is a voltage-reflectance characteristic of the display medium of the present invention.

FIG. 4 Voltage-reflectance characteristics of cholesteric liquid crystal

[Explanation of symbols]

1a, 1b substrate 2a, 2b electrodes 3a Non-fluid liquid crystal layer 3b Liquid crystal layer 4 Light-shielding layer 5 Photoconductive layer 5a, 5c charge generation layer 5b Charge transport layer 10 Handwriting method 11 Spacer 15 Control means 20 power supplies 25 Writing light irradiation means 30 electronic display medium

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/00 H04N 1/00 C (72) Inventor Yasunori Saito 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox stock Company Ebina Business Site (72) Inventor Tsunemasa Mita 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Ebina Business Site F-term (reference) 2H088 EA03 EA22 GA03 GA10 HA02 HA06 HA09 HA14 HA29 JA14 KA04 KA30 MA20 2H093 NA11 NA74 ND42 ND42 ND NE03 NE05 NE06 NG01 NG20 NH12 5C062 AA07 AA13 AA14 AB19 AB25 AB41 AB42 AC05 AC22 AC23 AE03 AE10 AE15 5C094 AA15 AA44 BA09 BA49 GA01 GA10 5G435 AA18 BB12 LL07

Claims (5)

[Claims] 1. A first cholesteric liquid crystal in which an image is recorded between a pair of electrodes by both irradiation of writing light carrying an image and application of a voltage between the pair of electrodes. Laminating a liquid crystal layer and a second liquid crystal layer made of cholesteric liquid crystal in which the pressed portion is reversibly compressed by the pressure and the liquid crystal inside flows and the trajectory of the pressed portion is recorded by the flowing action of the liquid crystal. An electronic display medium characterized by the following. 2. The electronic display medium according to claim 1, wherein the first and second liquid crystal layers have selective reflection wavelength regions different from each other. 3. The electronic display medium according to claim 1, wherein a photoconductive layer that absorbs light and changes in resistance value is laminated between the pair of electrodes. 4. The second liquid crystal layer has a higher phase transition voltage for phase transition from a cholesteric liquid crystal phase to a nematic liquid crystal phase than the first liquid crystal layer, and the second liquid crystal layer has a phase transition voltage between the pair of electrodes. By the application of the voltage when an image is recorded on the first liquid crystal layer due to the effects of both the irradiation of the writing light carrying the image on the first liquid crystal layer and the application of the voltage between the pair of electrodes. The electronic display medium according to claim 1, wherein the trajectory of the pressed portion is erased. 5. A first cholesteric liquid crystal in which an image is recorded between a pair of electrodes by both irradiation of writing light carrying an image and application of a voltage between the pair of electrodes. Laminating a liquid crystal layer and a second liquid crystal layer made of cholesteric liquid crystal in which the pressed portion is reversibly compressed by the pressure and the liquid crystal inside flows and the trajectory of the pressed portion is recorded by the flowing action of the liquid crystal. Voltage applying means for applying a voltage between the pair of electrodes of the electronic display medium, writing light irradiating means for irradiating the electronic display medium with writing light carrying an image, the voltage applying means and the writing Adjust the light irradiation means,
While recording an image on the first liquid crystal layer,
When the locus of the pressed portion is recorded on the liquid crystal layer of the second liquid crystal layer, the locus is erased, and the second liquid crystal layer is moved by the flow action of the liquid crystal while the image of the first liquid crystal layer remains unchanged. An image writing apparatus, comprising: a control unit that sets a state in which a locus is recorded.