JP2003167268A - Electronic display medium, electronic display medium writing method and image writing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic display medium having both a fixed display part and a variable display part, to provide an electronic display medium writing method by which an image can be fixedly recorded and an other image can be added to the electronic display medium and to provide an electronic display device using the writing method. <P>SOLUTION: A first and a second liquid crystal layers wherein an image is recorded by functions of both irradiation of writing light carrying the image and application of voltage between a pair of electrodes and which are both formed by using a cholesteric liquid crystal are laminated between the pair of electrodes to form the electronic display medium. In the first liquid crystal layer, the image is recorded by the irradiation of writing light carrying the image and the application of voltage between the pair of electrodes, by which the second liquid crystal layer stays in just a state the image in the case the image is recorded in the second liquid crystal layer is recorded whether the second liquid crystal layer is irradiated with light or not. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can be used for a recording medium such as a printer, a facsimile, a copying machine, an electronic newspaper, an electronic book, and a recording medium for recording an automatic recognition code such as a bar code. The present invention relates to an electronic / electronic display medium, an electronic / electronic display medium writing method, and an image writing apparatus capable of repeatedly writing and erasing data.

[0002]

2. Description of the Related Art Conventionally, there has been known an electronic / electronic display medium having a liquid crystal layer and a photoconductive layer laminated between a pair of electrodes.

FIG. 1 is a diagram showing an electronic display medium which has been conventionally used.

In the electronic and electronic display medium shown in FIG. 1, a liquid crystal layer 3, a light shielding layer 4 and a photoconductive layer 5 are laminated between a pair of electrodes 2a and 2b. When a voltage is applied between the electrode 2a and the electrode 2b of this electronic display medium, the divided voltage is applied to each of the liquid crystal layer 3, the light shielding layer 4, and the photoconductive layer 5. At this time, when the photoconductive layer 5 is irradiated with the writing light W, the resistance value of the photoconductive layer 5 decreases, thereby increasing the partial pressure of the liquid crystal layer 3 and changing the alignment state of the liquid crystal constituent molecules. When the orientation state of the liquid crystal constituent molecules changes, the optical characteristics such as the transmittance, the absorptance, and the reflectance of the liquid crystal layer 3 change, and the changes are used to function as an electronic display medium. In order to read this optical change of the liquid crystal layer 3, the reading light R is incident on the liquid crystal layer 3, but when the reading light R reaches the photoconductive layer 5, the resistance value of the photoconductive layer 5 changes, so that the liquid crystal layer A light blocking layer 4 is provided between the photoconductive layer 3 and the photoconductive layer 5 to block the reading light R.

In order to keep the optical change generated in the liquid crystal layer 3 as it is and preserve the display, a liquid crystal having a memory property is used for the liquid crystal layer 3 in which the changed alignment state is maintained even after the voltage is removed.
A cholesteric liquid crystal having a property of selectively reflecting in the visible wavelength range is preferably used.

Cholesteric liquid crystals have a helical molecular orientation, and are colored by selective reflection in a planar orientation (P orientation) in which the helical axis is substantially parallel to the substrate normal line, and the helical axis is almost perpendicular to the substrate normal line. In this focal conic orientation (F orientation), light is transmitted, so that the light is colored in the color of the light shielding layer (for example, black if the light shielding layer is black).

FIG. 2 is a schematic diagram showing the voltage-reflectance characteristic of a liquid crystal layer composed of cholesteric liquid crystal.

In FIG. 2, the vertical axis represents the reflectance of the liquid crystal layer and the horizontal axis represents the voltage of the liquid crystal layer. The characteristic curve in the figure shows the characteristic curve when the reflectance of the liquid crystal layer is measured after applying a voltage to the electrodes sandwiching the liquid crystal layer and releasing the voltage. The solid line A indicates that the initial orientation is the P orientation. Case, dotted line B
Is the case where the initial orientation is the F orientation.

When the applied voltage is V1 or less, the alignment state of the cholesteric liquid crystal does not change, so that the reflectivity does not change regardless of the initial alignment, which is a so-called dead zone. When the applied voltage is in the range of V2 or more and V3 or less, the F orientation becomes stable and a dark display is obtained. When the applied voltage is V4 or more, the P orientation becomes stable and bright display is obtained.

Here, V4 corresponds to a threshold voltage at which the cholesteric liquid crystal phase transitions to the nematic liquid crystal phase. Therefore, an appropriate voltage is applied between the electrodes 2a and 2b so that the voltage of the liquid crystal layer 3 becomes V3 or less when the writing light has a low light intensity and V4 or more when the writing light has a high light intensity. By applying, it becomes possible to write on the electronic display medium by writing light.

Japanese Unexamined Patent Publication No. 2000-111942 discloses that
In such an electronic display medium, a method of performing multicolor display by laminating a plurality of cholesteric liquid crystal layers having different display colors and threshold voltages between a pair of electrodes is disclosed.

FIG. 3 is a schematic diagram showing the voltage-reflectance characteristic when the liquid crystal layer has two layers.

In FIG. 3, the vertical axis represents the reflectance of the liquid crystal layer and the horizontal axis represents the sum of the voltages of the two liquid crystal layers 3a and 3b. The two liquid crystal layers 3a and 3b made of cholesteric liquid crystal have V2a <V1b and V2b <V3.
The threshold voltage is set so that a and V4a <V3b.

The voltage applied between the pair of electrodes is divided into two times, and at the first time, a voltage is applied such that the voltage changes within the range of V3b to V4b according to the intensity of the writing light. Thus, a desired image is written only on the liquid crystal layer 3b. Two
The voltage changes from V1a to V2a depending on the intensity of the writing light.
Is applied to the liquid crystal layer 3a.
Only the desired image is written. Voltage is from V1a to V
In the range of 2a, it is lower than the threshold voltage V1b at which the orientation of the liquid crystal layer 3b changes, so that the liquid crystal layer 3b is written in the second time.
Does not change the orientation. Cholesteric liquid crystal layers 3a, 3b
When the selective reflection colors of, for example, turquoise and red, the electronic display medium can display multicolors of four colors of white, turquoise, black, and red by an additive color mixture of turquoise and red.

[0015]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
The electronic display medium disclosed in Japanese Patent Publication No. 000-111942 is used for fixedly recording an image on each of two liquid crystal layers. Therefore, when it is desired to use one of the two liquid crystal layers as a rewritable variable recording medium, for example, an electronic display medium is used as a commuter pass, the liquid crystal layer 3b is used as a fixed display portion such as a station name, and the liquid crystal layer 3a is used as a ticket gate. In the case of a variable display unit that is rewritten each time it is used, such as passage recording, a voltage in the range of V1a to V2a is applied to the electrodes to apply liquid crystal layer 3a.
Can be changed from bright display to dark display (record erasure), but when a voltage in the range of V3a to V4a is applied to the electrodes to change from dark display to bright display (record is rewritten), the fixed display portion is displayed. The liquid crystal layer 3b also becomes a dark display and the record is erased. As described above, the liquid crystal layer 3a can only change from bright display to dark display to erase the record, and cannot be repeatedly rewritten.

There is a great demand for an electronic display medium having both a fixed display part and a variable display part, not limited to a commuter pass, but it is difficult to do this with a conventional electronic display medium.

In view of the above circumstances, the present invention allows an electronic display medium having both a fixed display portion and a variable display portion, and an image can be fixedly recorded or another image can be additionally written on the electronic display medium. An object of the present invention is to provide an electronic display medium writing method and an image writing apparatus using the writing method.

[0018]

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. An image is recorded by the action of both of the above, and an electronic display medium in which a first liquid crystal layer and a second liquid crystal layer both formed of cholesteric liquid crystal are laminated, and the first liquid crystal layer carries an image. Of the writing light and the image is recorded between the pair of electrodes when an image is recorded on the second liquid crystal layer regardless of whether or not the second liquid crystal layer is irradiated with light. It is characterized in that the image is recorded by applying a voltage that remains in the state as it is.

Here, it is also a preferred embodiment that a photoconductive layer that absorbs light and changes its resistance value is laminated between the pair of electrodes.

In the electronic display medium writing method of the present invention which achieves the above object, both of irradiation of writing light for carrying an image and application of a voltage between the pair of electrodes are performed between the pair of electrodes. An image is recorded by the action, and an electronic display medium, in which first and second liquid crystal layers each of which is formed of a cholesteric liquid crystal are laminated, is irradiated with writing light for carrying an image, and a space is provided between the pair of electrodes. After the image is recorded on the second liquid crystal layer by the action of both the application of the voltage and the second liquid crystal layer, the second liquid crystal layer between the pair of electrodes is irradiated with light regardless of the presence or absence of light irradiation. When an image is recorded on the liquid crystal layer, the image recorded on the first liquid crystal layer is erased by applying a voltage that keeps the image recorded.

The image writing apparatus of the present invention which achieves the above-mentioned object is realized by the action of both the irradiation of writing light for carrying an image and the application of the voltage between the pair of electrodes between the pair of electrodes. An electronic display medium, on which an image is recorded, in which first and second liquid crystal layers, both of which are formed of cholesteric liquid crystal, are laminated, wherein the first liquid crystal layer is a layer of a writing light carrying an image. Irradiation and a state where the image is recorded between the pair of electrodes, in the case where an image is recorded on the second liquid crystal layer regardless of whether the second liquid crystal layer is irradiated with light or not. An image writing device that writes an image on an electronic display medium on which the image is recorded by applying a voltage that remains at, and a voltage is applied between a pair of electrodes of the electronic display medium in a state of being arranged at a predetermined image writing position. Voltage applying means to be applied and the electronic table An image is written on the second liquid crystal layer by adjusting the writing light irradiating means for irradiating the medium with writing light for carrying an image, the voltage applying means, and the writing light irradiating means, and By adjusting the voltage applying means and the writing light irradiating means, when the image is recorded on the second liquid crystal layer, the image is recorded on the first liquid crystal layer. And an image writing control unit.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION First, a first embodiment of the present invention will be described.

The first embodiment corresponds to the embodiment of the electronic display medium of the present invention.

FIG. 4 is a schematic view showing a cross section of the electronic display medium of the first embodiment.

The electronic display medium shown in FIG. 4 has a transparent substrate 1.
The liquid crystal layer 3a and the liquid crystal layer 3b made of cholesteric liquid crystal between the transparent electrode 2a formed on a and the transparent electrode 2b formed on the transparent substrate 1b, and the resistance value when light is absorbed. The changing photoconductive layers 5 are respectively laminated, and further, the light shielding layer 4 for shielding the light transmitted through the liquid crystal layer from reaching the photoconductive layer is laminated between the photoconductive layer 5 and the electrode 2b.

Here, in the present embodiment, the photoconductive layer 5 is laminated to control the voltage applied to the liquid crystal layers 3a and 3b. However, it is not always necessary to laminate the photoconductive layer 5 and the electrode 3a is not necessarily required to be laminated. , 3b may be of a simple matrix type and line-sequential scanning may be performed, or an active matrix drive may be performed to apply a voltage V to the liquid crystal layers 3a and 3b to record an image.

For the liquid crystal layer 3, a cholesteric liquid crystal having a memory property so that the optically changed alignment state can be maintained even after the voltage is removed and having a property of selectively reflecting in the visible wavelength region is preferably used. Cholesteric liquid crystal has a helical molecular orientation, and is colored by selective reflection in the planar orientation (P orientation) in which the spiral axis is substantially parallel to the substrate normal line, and the focal conic in which the spiral axis is almost perpendicular to the substrate normal line. Orientation (F
In the (orientation) direction, light is transmitted and the color of the light shielding layer (for example, black if the light shielding layer is black) is exhibited.

When a voltage V is applied between the electrode 2a and the electrode 2b of this electronic display medium, the partial voltage of the voltage V is applied to each of the liquid crystal layer 3, the light shielding layer 4 and the photoconductive layer 5. When the photoconductive layer 5 is irradiated with the writing light W at this time, the resistance value of the photoconductive layer 5 decreases, and the partial pressure of the liquid crystal layer 3 increases accordingly, so that the alignment state of the liquid crystal constituent molecules changes. . When the orientation state of the liquid crystal constituent molecules changes, the transmittance of the liquid crystal layer 3,
Since optical characteristics such as absorptance and reflectance change, it is possible to function as an electronic display medium by utilizing the change. In order to read this optical change of the liquid crystal layer 3, the reading light R is made incident on the liquid crystal layer 3. When the reading light R reaches the photoconductive layer 5, the resistance value of the photoconductive layer 5 changes and the behavior of the liquid crystal layer is changed. Fluctuates and affects the display.
A light-shielding layer 4 between the liquid crystal layer 3 and the photoconductive layer 5
Is provided. If the reading light R can be shielded at the time of writing, the light shielding layer 4 is not necessarily required at this position.

As the electrodes 2a and 2b, a metal thin film such as Au, ITO (Indium Tin Oxide),
A light-transmitting conductor such as an oxide conductor such as SnO ₂ or ZnO or a conductive polymer such as polypyrrole is used.

The liquid crystal layer 3 is a cyanobiphenyl group,
Phenyl cyclohexyl type, phenyl benzoate type,
Known nematic liquid crystal compositions such as cyclohexylbenzoate-based, azomethine-based, azobenzene-based, pyrimidine-based, dioxane-based, cyclohexylcyclohexane-based, stilbene-based, and tolan-based compounds are added to cholesterol derivatives and 2
A substance to which a chiral agent such as an optically active compound such as a methylbutyl group is added can be used. The liquid crystal composition itself may be an optically active compound.

Additives such as dyes and fine particles may be added to the cholesteric liquid crystal. The cholesteric liquid crystal may be dispersed in a matrix composed of a polymer or an inorganic material, gelled using a crosslinkable polymer or a hydrogen bonding gelling agent, or microcapsulated. Further, it may be any of high molecular liquid crystal, medium molecular liquid crystal, low molecular liquid crystal, and a mixture thereof.

Cholesteric liquid crystals have a selective reflection wavelength of 4
The present invention is not limited to those in the visible wavelength range of 00 nm to 800 nm, and can be applied as a scattering-transmission type cholesteric liquid crystal even if the selective reflection wavelength is in the near infrared wavelength range.

Since the selective reflection wavelength is given by the product of the average refractive index and the spiral pitch, it can be controlled to a desired wavelength by setting the spiral pitch to an appropriate size. The liquid crystal layers 3a and 3b generally have a spiral pitch of 2
It is necessary to set the thickness more than twice, and in order to obtain a desired reflectance at the time of bright display, it is necessary to set it in the range of several μm to several tens μm.

The threshold electric field Ecn for transition from the cholesteric liquid crystal phase to the nematic liquid crystal phase is Ecn = (π ² / p)
It is given by √ (K ₂₂ / ε ₀ · Δε).

Here, p is the pitch of the spiral, K ₂₂ is the elastic modulus of twist orientation, ε ₀ is the dielectric constant of vacuum, and Δε
Is the dielectric anisotropy.

Therefore, by setting K ₂₂ or Δε of the liquid crystal layers 3a and 3b to an appropriate value so that Ecn has a sufficiently large difference, the threshold value at which the liquid crystal layer 3a transitions from the cholesteric phase to the nematic phase. The voltage becomes equal to or lower than the threshold voltage at which the orientation of the liquid crystal layer 3b changes, that is,
It can be set such that V4a <V1b.

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 complex of a charge generation material that generates a charge and a charge transport material that causes a charge transfer by an electric field; examples of the charge generation 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, a material that absorbs both writing light and reading light is used. Although it cannot be generally stated because it depends on the sensitivity of the photoconductive layer 4 and the intensity of the writing light and the reading light, it is desirable that the transmission optical density of the light shielding layer 4 is at least 1 or more, more preferably 2 or more. Further, if the electric resistance of the light-shielding layer 4 is low, it causes a decrease in resolution.
It is desirable to have a resistivity of at least 10E8 (Ω · cm) or more. Furthermore, in order to increase the partial voltage of the voltage applied to the liquid crystal layers 3a and 3b, the larger the capacitance of the light shielding layer 4, the better. Therefore, it is preferable that the dielectric constant is large and the layer thickness is thin. As a material for 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.

The liquid crystal layer 3a of the electronic display medium of this embodiment,
When a cholesteric liquid crystal having a memory property is used for 3b, it is not limited to a display mode utilizing selective reflection, and a display mode utilizing changes in birefringence, optical rotatory power, extinction coefficient, etc. may be used. Good. 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. In addition, the liquid crystal layers 3a and 3b
Since the selective reflection wavelength of can be set arbitrarily, different colors can be displayed on both the fixed display portion and the variable display portion by using different selective reflection wavelengths.

FIG. 5 is a diagram showing the voltage-reflectance characteristic of each of the two liquid crystal layers of this embodiment.

In FIG. 5, the vertical axis represents the reflectance of the liquid crystal layer,
The horizontal axis represents the sum of the voltages of the liquid crystal layers. The characteristic curve in the figure shows the characteristic curve when the reflectance of each liquid crystal layer is measured after applying a voltage to the electrodes sandwiching the liquid crystal layer and releasing the voltage. The solid line shows the characteristic curve of the liquid crystal layer 3b. , The dotted line represents the characteristic curve of the liquid crystal layer 3a.

The liquid crystal layer 3b transitions to a nematic liquid crystal phase for a bright display when the voltage is V4b or higher, but becomes a dark display when the writing light is irradiated in the voltage range of V1b to V2b. On the other hand, the liquid crystal layer 3a transitions to a nematic liquid crystal phase for a bright display when the voltage becomes V4a or higher, but becomes a dark display when the writing light is irradiated in the voltage range of V1a to V2a. Further, V4a has a smaller voltage than V1b.
To write an image on this electronic display medium, first, the electrode 2
By applying a voltage between the a and the electrode 2b such that the voltage changes in the range of V3b to V4b according to the writing light intensity, and irradiating the writing light carrying an image, the liquid crystal layer 3b is irradiated with a desired image. Write. At this time, since the liquid crystal layer 3a is brightly displayed, if necessary, a voltage of V2a or more and V3a or less may be applied to reset the dark display to erase the image.
When additional writing is performed on the electronic display medium with the desired image being written in the liquid crystal layer 3b, the voltage between the electrodes 2a and 2b varies from V3a to V4a depending on the writing light intensity.
By applying a voltage that changes in the range of 1) and irradiating the writing light carrying the write-once image, the write-once image can be written on the liquid crystal layer 3a.

As described above, the threshold voltage V4 for causing the liquid crystal layer 3a to transition from the cholesteric liquid crystal phase to the nematic liquid crystal phase.
a is a threshold voltage V1b at which the molecular orientation of the liquid crystal layer 3b changes.
To V2b, the image recorded on the liquid crystal layer 3b remains unchanged even if the image is repeatedly rewritten on the liquid crystal layer 3a. Therefore, the liquid crystal layer 3
If b is a fixed display part and the liquid crystal layer 3a is a variable display part, only the image of the variable display part can be erased or written without erasing the image of the fixed display part. In this case, after the fixed display is performed on the liquid crystal layer 3b and the variable display portion of the liquid crystal layer 3a is set in the dark state to erase the image,
Since it can be distributed to the user of the electronic display medium, only the additional write operation can be performed without the user performing the erasing process of the variable display section.

Next, the second embodiment, which describes the second embodiment of the present invention, corresponds to the embodiment of the electronic display medium writing method and the image writing apparatus of the present invention.

FIG. 6 is a block diagram showing the arrangement of the image writing apparatus of the second embodiment.

The image writing apparatus shown in FIG. 6 has a voltage applying unit 20, an image projecting unit 30 for projecting writing light on the electronic display medium 10, a voltage applying unit 20, and an image projecting unit 30.
The electronic display medium 10 on which the image is written is set at a predetermined writing position.

A predetermined voltage is applied from the voltage applying means 20 to the pair of electrodes of the electronic display medium 10 set at a predetermined writing position, and the photoconductive layer of the set electronic display medium 10 is laminated on the side. The writing light is projected by the image projection device 30 from. The controller 40 controls the voltage and timing applied to the electronic display medium 10 in the voltage application unit 20, and the controller 40 controls the irradiation timing of the writing light in the image projection apparatus 30.

As the electronic display medium 10, the same one as described in the first embodiment is used. Electronic display medium 10
Is configured to be freely attached to and detached from the electronic display device, but is not necessarily limited to this.
It may be fixed.

The image projection device 30 is used to project writing light onto the photoconductive layer of the electronic display medium 10 and record an image according to the writing light on the electronic display medium 10.

Here, even if the writing light is two-dimensionally scanned by a spotlight such as a laser, the writing light is an LED.
A linear light image using an array or a liquid crystal array may be one-dimensionally scanned, or a two-dimensional light image such as a CRT or LCD may be projected. The writing light may be projected by bringing it into close contact with the surface of the electronic display medium 10 on which the photoconductive layer is laminated, or by using a lens array or the like to electronically display an optical image of an image to be recorded. The image may be projected on the photoconductive layer of the medium 10.

The voltage applying means 20 sets a pair of threshold voltages when the cholesteric liquid crystal phase is changed to the nematic liquid crystal phase and a threshold voltage when the molecular orientation is changed in each of the two liquid crystal layers. It is configured so that a voltage can be applied between the electrodes.

The controller 40 adjusts the voltage and timing applied from the voltage application means 20 to the electronic display medium 10, the irradiation timing of the writing light projected from the image projection device 30, and the like, and the image is based on the operator's instruction. To record.

FIG. 7 is a schematic diagram showing the relationship between the write light intensity and the applied voltage instructed by the controller.

In FIG. 7, the vertical axis represents the reflectance of the liquid crystal layer, the horizontal axis represents the voltage applied to the pair of electrodes, and the dotted line in the figure represents the voltage-reflectance characteristic of the liquid crystal layer 3a of the electronic display medium.
The solid line in the figure represents the voltage-reflectance characteristic of the liquid crystal layer 3b of the electronic display medium. Also, for both the dotted and solid lines, A
Indicates that light is transmitted and is in a dark state because writing light is not emitted, and B indicates that light is reflected and writing is in a bright state because writing light is emitted, and Va or Vb is applied. The voltage-reflectance characteristic of the liquid crystal layer shifts according to the intensity of the writing light, and a reflectance distribution corresponding to the intensity of the writing light is obtained.

Therefore, when the image of the liquid crystal layer 3b is rewritten, the voltage Vb is applied to the electrodes from the voltage applying means, and the writing light is irradiated from the image projecting means, the image corresponding to the intensity of the writing light is obtained. It is recorded in 3b. Also,
When the image of the liquid crystal layer 3a is rewritten, the voltage Va is applied to the electrodes from the voltage applying unit, and the writing light is emitted from the image projecting unit, whereby an image according to the intensity of the writing light is recorded in the liquid crystal layer 3a. . At this time, the voltage Va is equal to the liquid crystal layer 3b.
Since the voltage is smaller than the voltage that changes the molecular orientation of the liquid crystal layer 3,
The image recorded in b is maintained as it is. Further, by applying a voltage slightly higher than the voltage Va without irradiating the writing light, the image recorded in the liquid crystal layer 3a is erased while maintaining the state of the image recorded in the liquid crystal layer 3b. You can also

FIG. 8 is a flow chart of an electronic display medium writing method using the image writing apparatus of this embodiment.

In FIG. 8, the operator sets the electronic display medium in the image writing device, connects the pair of electrodes to the output terminal of the voltage applying means, and follows the guide displayed on the controller to the liquid crystal layer 3b. To record the image. The controller commands an image to be projected and the light intensity to the image projection device at a timing according to the instruction of the operator, and the image projection device projects the writing light having the instructed predetermined intensity on the electronic display medium (S). -1).

Next, the voltage applying means applies the voltage Vb to the electronic display medium for a predetermined time at the timing commanded by the controller (S-2).

When the writing light is projected for the commanded time, the controller ends the projection from the image projection device (S-3).

Further, when the operator gives an instruction to record an image on the liquid crystal layer 3a, the controller gives an instruction of an image to be projected and the light intensity to the image projection device at a timing according to the instruction of the operator, and the image projection device gives the instruction. The writing of the written light having the predetermined intensity is started to be projected on the electronic display medium (S-4).

Then, the voltage applying means applies the voltage Va to the electronic display medium for a predetermined time at the timing instructed by the controller (S-5).

Here, it is judged whether or not there has been a further rewriting instruction to the liquid crystal layer 3a from the operator (S
-6), if there is an instruction to rewrite the image record, (S-
4) and (S-5) are repeated, and when there is no operator's rewriting instruction, the image recording is ended (S-7).

[0063]

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

FIG. 9 is a sectional view showing an embodiment of the electronic display medium of the present invention.

The electronic display medium shown in FIG. 9 has an electrode 2a formed on the substrate 1a and an electrode 2 formed on the substrate 1b.
liquid crystal layer 3a and liquid crystal layer 3b, and charge generation layer 5 between b
The photoconductive layer 5 including a, the charge transport layer 5b, and the charge generation layer 5c is stacked, and the light shielding layer 4 is stacked between the photoconductive layer 5 and the electrode 2b.

A commercially available ITO vapor-deposited PET resin film is used for the substrate 1b and the electrode 2b, and a photoconductive layer 5 having a three-layer structure of a first charge generation layer 5a, a charge transport layer 5b, and a second charge generation layer 5c is formed thereon. 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 first charge generation layer 5a having a thickness of 0.1 μm, and then a chlorobenzene solution of a diamine-based charge transport material and a polycarbonate resin. Is coated with an applicator to form a charge transport 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 again to form a second charge having a thickness of 0.1 μm. Generation layer 5
c was formed to obtain a photoconductive layer 5. Then, an acrylic resin solution in which a carbon black pigment was dispersed was spin-coated to obtain a light shielding layer 4.

Next, a commercially available ITO vapor-deposited PET resin film was used as the substrate 1a and the electrode 2a, and two kinds of cholesteric liquid crystal microcapsule paints having different threshold voltages were prepared on this, and these were successively applied in a thickness of 30 μm to form a liquid crystal The layers are 3a and 3b. An adhesive was applied to the four sides of this substrate, which was passed through a laminator to be bonded to the above-mentioned substrate 1b to produce an electronic display medium.

As a cholesteric liquid crystal for the liquid crystal layer 3a, a nematic liquid crystal MLC-6294 (manufactured by Merck & Co., Δ
Chiral agent R811 (manufactured by Merck) for ε = 2.4) 16
% And 4% of a chiral agent R1011 (manufactured by Merck Ltd.) were added to obtain a cholesteric liquid crystal having blue-green selective reflection. On the other hand, the nematic liquid crystal ML is used as the liquid crystal layer 3b.
C-6237-000 (Merck, Δε = 30.8) was added with a chiral agent R811 (manufactured by Merck) 11.2% and a chiral agent R1011 (manufactured by Merck) 2.8% to give a red color. A cholesteric liquid crystal having selective reflection was obtained.

Polyisocyanate compound Takenate D-110N (manufactured by Takeda Pharmaceutical Co., Ltd.) and ethyl acetate were added to these cholesteric liquid crystals to prepare an oil phase composition, which was put into a 1% aqueous polyvinyl alcohol solution and stirred.
It was emulsified to prepare an O / W emulsion having a diameter of about 10 μm. This was heated at 60 ° C. for 3 hours to obtain microcapsules having polyurethane as a wall material. After the microcapsules were collected by centrifugation, an aqueous polyvinyl alcohol solution was added to obtain a microcapsule paint.

The mask pattern A is projected on the photoconductive layer 5 of the produced electronic display medium by an LED light source having a wavelength of 650 nm, and a voltage of 250 V is applied between the electrodes 2a and 2b to form the mask pattern A on the liquid crystal layer 3b. I wrote it. Next, the mask pattern B is projected to apply a voltage 30 between the electrodes 2a and 2b.
By applying V, the mask pattern B was written on the liquid crystal layer 3a. As a result, the mask pattern B could be clearly written on the electronic display medium on which the mask pattern A was recorded.

[0071]

According to the present invention, it is possible to provide an electronic display medium that has both the functions of a fixed display section for fixedly recording an image and a variable display section for variably recording an image. Further, an electronic display medium writing method and an writing method thereof, in which an image can be fixedly recorded on the electronic display medium, or another image can be additionally written or erased while the fixedly recorded image is left as it is It is possible to provide an electronic display device using the.

[Brief description of drawings]

FIG. 1 is a diagram showing an electronic electronic display medium which has been conventionally used.

FIG. 2 is a schematic diagram showing voltage-reflectance characteristics of a liquid crystal layer composed of cholesteric liquid crystal.

FIG. 3 is a schematic diagram showing voltage-reflectance characteristics in the case of two liquid crystal layers.

FIG. 4 is a schematic view showing a cross section of the electronic display medium of the first embodiment.

FIG. 5 is a diagram showing voltage-reflectance characteristics of each of the two liquid crystal layers of the present embodiment.

FIG. 6 is a block diagram showing a configuration of an electronic display device of a second embodiment.

FIG. 7 is a schematic diagram showing the relationship between the intensity of writing light commanded by the controller and the applied voltage.

FIG. 8 is a flowchart of an electronic display medium writing method using the image writing device of the present embodiment.

FIG. 9 is a sectional view showing an example of the electronic display medium of the present invention.

[Explanation of symbols]

1a, 1b substrate 2a, 2b electrodes 3a, 3b liquid crystal layer 4 Light-shielding layer 5 Photoconductive layer 5a, 5c charge generation layer 5b Charge transport layer 10 Electronic display medium 20 voltage applying means 30 image projection device 40 controller W writing light R reading light

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasunori Saito             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Co., Ltd. Ebina Office (72) Inventor Tsunemasa Mita             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Co., Ltd. Ebina Office F-term (reference) 2H088 EA37 EA62 GA03 JA14 MA02                       MA03 MA04 MA10 MA16                 2H092 JB51 LA02 LA05 LA06 LA12                       LA16 MA05 MA35 NA25 PA09                       QA11 RA04                 5C006 AF33 AF52 BA11 BB08 BD01                 5C094 AA51 AA54 BA07 BA09 BA12                       BA13 BA49 CA24 DA01 GA01                       HA10

Claims (4)

[Claims] 1. 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, both of which are formed of cholesteric liquid crystal. An electronic display medium having a first liquid crystal layer and a second liquid crystal layer laminated, wherein the first liquid crystal layer is irradiated with writing light carrying an image,
A voltage between the pair of electrodes that keeps the image recorded when the second liquid crystal layer records an image regardless of the presence or absence of light irradiation. The electronic display medium is characterized in that the image is recorded by the application of. 2. The electronic display medium according to claim 1, wherein a photoconductive layer which absorbs light and changes in resistance value is laminated between the pair of electrodes. 3. 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, both of which are made of cholesteric liquid crystal. The second liquid crystal is applied to the electronic display medium in which the first and second liquid crystal layers are laminated by both the irradiation of the writing light for carrying an image and the application of the voltage between the pair of electrodes. After the image is recorded on the layer, the image is recorded between the pair of electrodes regardless of whether the second liquid crystal layer is irradiated with light or not. An electronic display medium writing method, characterized in that an image recorded in the first liquid crystal layer is erased by applying a voltage that remains as it is. 4. 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, both of which are made of cholesteric liquid crystal. An electronic display medium in which first and second liquid crystal layers are laminated, wherein the first liquid crystal layer is irradiated with writing light for carrying an image, and the first liquid crystal layer is provided between the pair of electrodes. When an image is recorded on the second liquid crystal layer regardless of whether or not the second liquid crystal layer is irradiated with light, the image is recorded by applying a voltage that keeps the image as recorded. An image writing device for writing an image on an electronic display medium, comprising: a voltage applying unit for applying a voltage between a pair of electrodes of the electronic display medium arranged at a predetermined image writing position; and an image on the electronic display medium. Writing that radiates writing light that carries Adjusting the voltage application unit and the writing light irradiation unit while writing an image on the second liquid crystal layer by adjusting the irradiation unit, the voltage application unit, and the writing light irradiation unit. Thus, when an image is recorded on the second liquid crystal layer, the first
And an image writing device for writing an image on the liquid crystal layer.