JPS62249126A - Electrochromic display device - Google Patents

Abstract

PURPOSE:To eliminate the need for impressing a voltage via leads to a counter electrode and to increase display density by controlling a driving voltage via a photoconductive layer controlled by light from the light source. CONSTITUTION:Transparent display electrodes 3, an electrochromic material 4 partitioned to a display shape by insulating columns 9, electrolytes 10 sandwiching a background material 11, the counter electrode 10, the photoconductor layer 7, a transparent conductor layer 6, etc., are provided between front and rear transparent substrates 2 and 5 of a display panel 1. The display driving or erasing voltage is impressed between the electrode 3 and the layer 6 via a DC power source 12. The electrodes 8 and electrodes 3 of the display part corresponding to each other via the layer 7 is conducted according to the irradiation position and electrochromic display is executed when an LED 14 is lighted up according to display information. The display is held when the LED 14 is put out and the voltage is interrupted. The erasing by the different driving voltage is similarly executed. There is no need for providing the leads of the fine pattern corresponding to the display to the counter electrode and the display density is increased by diminishing the arrangement space of the counter electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrochromic display device.

(Technical background of the invention and its problems) Electrochromic display devices are capable of reducing/! i! Display is performed using an electrochromic material (hereinafter referred to as EC1!1 quality) that colors/discolors through a chemical reaction. Conventionally, this electrochromic display device has a transparent display electrode on the front transparent substrate surface. EC material layers are formed on the display electrodes in the shape of display pixels, and counter electrodes are arranged on the back side substrate surface to face each EC material layer on the front side transparent substrate. Are known.

This electrochromic display Hffi performs display by applying a driving voltage between the display electrode of the front side transparent substrate and the opposing N pole of the back side (I11 base plate).
When a display drive voltage equal to the potential of the counter electrode is applied to the display electrode, charge is injected into the EC material layer, a reduction reaction occurs within the EC material, and the EC material layer changes to a W color and assumes its shape. The corresponding pixels are displayed. Furthermore, in order to erase the display, it is sufficient to apply a positive erase drive voltage to the display electrode with respect to the potential of the counter electrode, and when this erase drive voltage is applied, the EC substance causes an oxidation reaction opposite to that during coloring. to erase the color.

By the way, the electrochromic display device performs display and erasing by switching the polarity of the driving voltage applied between the display electrode and the counter N-pole. To erase and display an image, each counter electrode is made independent (the display electrode may be a common electric bridge), and a driving voltage is selectively applied between the display electrode and each counter electrode using static drive. There is a need to. For this reason, in conventional electrochromic display devices, each opposing N-pole is arranged and formed independently, and leads are formed by leading out from each opposing electrode to the side edge of the back side transparent substrate. A drive vJ voltage is applied to each opposing electrode through the two electrodes.

However, in order to derive a lead from each counter electrode in this way, the lead must be routed between each counter electrode, and in order to do this, the arrangement interval of the counter electrodes must be increased to increase the lead wiring spacing between the counter electrodes. At the same time, it is necessary to increase the spacing between the EC material layers formed on the front transparent substrate facing the counter electrodes. Therefore, in conventional electrochromic display devices, the density of display pixels is low and the resolution is low. I had a bad problem.

[Purpose of the invention]

This invention was made in view of the above-mentioned circumstances, and its purpose is to connect this counter electrode to the front surface side without leading out the leads from the counter electrode formed on the back side substrate surface. An electrochromic display device is provided, in which a driving all voltage can be applied between a display electrode on a substrate, and the density of display pixels can be increased by eliminating the need to ensure lead wiring spacing between opposing electrodes. It is about providing.

[Summary of the invention]

That is, in the electrochromic display device of the present invention, a transparent display electrode is formed on the surface of a transparent substrate on the front side, an EC material layer is formed in the shape of a display pixel on the surface of the transparent display electrode, and an EC material layer is formed on the surface of the transparent substrate on the back side. A transparent conductive N layer and a photoconductor layer covering the transparent conductive layer are provided, and a counter electrode facing the EC material layer is formed on the photoconductor layer, and a display electrode of the front side transparent substrate and a back side are formed. For display/erasing, a drive voltage is applied between the transparent W# conductive layers of the side transparent substrate, and light is irradiated on the back side of the back side transparent substrate to a portion corresponding to the counter electrode of the photoconductor layer. It is characterized by being provided with a light source.

In other words, in the present invention, by irradiating a portion of the photoconductor layer corresponding to the counter electrode with light, the resistance value of the light irradiated portion of the photoconductor layer is lowered, and the counter electrode is replaced with the photoconductor layer. It is designed to conduct with the transparent conductive II layer below, and a driving voltage is applied between the display electrode on the front transparent substrate and the transparent conductor 11 on the back transparent substrate, and the counter electrode is connected to the transparent conductive layer by light irradiation. When electrical conduction is established between the display electrode and the counter electrode, a potential difference is generated between the display electrode and the counter electrode, so that reduction and oxidation reactions occur in the EC material layer on the surface of the display electrode, thereby making it possible to display and erase the display.

In this invention, a potential difference is generated between the display electrode and the counter electrode by making the counter electrode conductive with the transparent conductive layer through light irradiation. Therefore, a voltage is applied to the counter electrode via the lead. Therefore, according to the present invention, there is no need to ensure a lead wiring interval between the opposing electrodes, so the arrangement interval of the opposing electrodes is reduced, and the arrangement interval of the EC material vI layer is reduced accordingly. The display pixel density can be increased by reducing the size of the display pixel.

(Embodiments of the invention) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross section of a portion of an electrochromic display. This electrochromic display device is
It has a large screen with a display area of 800im x 1200am.
A still image is displayed at a display speed of 120 seconds per screen using a full dot matrix with a dot density of about 0.5 to i dot/m.

To explain the structure of this electrochromic display device, 1 in FIG. 1 is a display panel, and this display panel 1 has the following structure.

That is, 2 is a front-side transparent substrate made of a glass plate, and the inside surface of this front-side transparent substrate 2 is coated with a transparent conductive material (ITo) over its entire surface.

Transparent display electrode 3 made of (3n 02 , In203, etc.)
About 1,000 people are formed with a zero film thickness. Note that this display electrode 3 may be formed by sandwiching a metal net or the like having a fine wire diameter between it and the transparent substrate 2, and in this way, the display electrode 3 can be made into a low-resistance electrode. Also, 4.4
is a transparent EC material layer arranged on three surfaces of the transparent display N pole of the two surfaces of the front transparent substrate. This EC material layer 4.
4 is WO3, MO03, Ti 02 , V20S.

It is made of EC'JIJ quality such as Ir(O)-1)2, and its film thickness is said to be about 3,000 to 5,000 layers.

The E C** layers 4, 4 are formed in a roughly square pixel shape, and when displaying at a dot density of 1 dot/m on the display area of 80ONI x 1200InIR, 800 dots (vertical) x 1200g (horizontal) are formed. Arranged in a matrix.

On the other hand, reference numeral 5 denotes a rear transparent substrate made of a glass plate, and a transparent conductive layer 6 made of a transparent conductive material is formed over the entire inner surface of this rear transparent substrate. A photoconductor layer 7 is formed to cover the entire surface of the conductive layer 6. This photoconductor FR7 is
In the absence of light, it has insulating properties, and when exposed to light, its resistance value decreases and it becomes conductive. This is a photoconductor! !
7 is selenium (amorphous selenium), selenium alloy (Se −
(Te, Se-As, 5e-8, etc.), zinc oxide-resin system (ZnO dispersed in resin), zinc or cadmium sulfide-resin system (ZnS or CdS dispersed in resin) It consists of organic photoconductors, etc., which are currently being researched.

Further, reference numeral 8.8 denotes counter electrodes arranged on the photoconductor 117 so as to face each of the EC material layers 4, 4 of the front side transparent substrate 2, and these counter electrodes 8,8.
is a transparent conductive material or ALI.

It is made of a metal conductive material such as Ag or N+.

This counter electrode 8.8 has almost the same shape as the EC material layers 4, 4, and is arranged in a dot matrix like the EC material w14.4.

The front side transparent substrate 2 and the back side transparent substrate 5 are adhesively bonded at the outer periphery with a sealing material such as epoxy resin (not shown) while facing each other at a predetermined interval. Each pixel display portion (the portion where the EC material layer 4.4 and the counter electrode 8.8 face each other) is individually partitioned by an insulating partition material 9. In addition, a transparent electrolyte 10 (H28
04 or L i C104 and a non-aqueous solvent), and a porous background material 11 that becomes the background color when the display is erased is sandwiched in this electrolytic solution layer.

Further, in FIG. 1, reference numeral 12 is a display driving DC power source whose polarity is switched according to display/erase driving of the display device, and the display electrode 3 of the front side transparent substrate 2 is connected to this DC power source 12.
The transparent conductor layer 6 of the front transparent substrate 5 is connected to a ground line GND.

On the other hand, in FIG. 1, reference numeral 13 denotes a jlii! provided on the back side of the display panel 1. This drawing 1 / erasing head 13 irradiates light toward each pixel display section of the display panel 1 inside the vertically long head main body 13 a along the vertical direction of the display panel 1. A large number of luminance light emitting diodes (hereinafter abbreviated as LEDs) 14 are connected to the head body 1.
The LEDs 14 are arranged in rows along the length direction of the display panel 1, and the LEDs 14 correspond to the vertical arrangement pitch of each of the counter electrodes 8.8 arranged on the transparent substrate 5 on the back side of the display panel 1. The same number as the number of vertically facing electrodes (800)
The LEDs 14 are arranged in a line, and the light from each LED 14 passes through a lens system 15 and is illuminated in a spot on a portion of the photoconductor layer 6 of the display panel 1 that corresponds to the counter electrode 8. There is.

Further, this drawing 7' erasing head 13 is moved by a head feeding mechanism (not shown) in a direction perpendicular to the L, ED arrangement direction, that is, in a lateral direction of the display panel 1, so as to scan the entire display panel 1. and each of the LEDs 14
is selectively driven to emit light in accordance with the drawing/erasing signal in synchronization with the scanning movement of the drawing/erasing head 13.

To explain the operation of the above-mentioned electrochromic display device, when this electrochromic display device performs display, the display electrode 3 of the display panel 1 is connected to the DC power source 1.
A display drive voltage of about 2 to 1 V is applied. This display part 1111i pressure is applied to b, 1 seedling image, and erasure head 1.
When the LED 14 of No. 3 is not emitting light, the photoconductor layer 7 does not receive light and remains in an insulated state, so the counter electrode 8 on the photoconductor layer 7 does not act as an electric current. be.

Therefore, in this state, no potential difference occurs between the display section *3 and the counter electrode 6, so the ECS material M4 on the display electrode 3 surface
There is no change. When the LED 14 of the drawing 2/' erasing head 13 emits light in response to the drawing signal, the lens system 15
The spot light that has passed through the display panel 1 passes through the back side transparent substrate 5 and the transparent 4-electrode 6 and illuminates a portion of the photoconductor 16 that corresponds to the counter electrode 8 . When this photoconductor 16 is irradiated with a spot light, the resistance value of the light irradiated part of this photoconductor M6 decreases, and the opposing N pole 8 of this part is electrically connected to the transparent conductive layer 6, and this opposing electrode 8 is connected to the transparent conductive layer 6. The photoconductor layer 6 and the transparent conductive layer 6 are connected to the ground line GND. In this state, the display electrode 3 and the opposing 1
A potential difference of about -1.5V is generated between the electrode 8 and the EC material layer 4 on the display electrode 3 surface, and an environmental effect occurs within the EC material 14, causing the transparent EC material layer 4 to become colored. (For example, if the EC material is WO3 and the electrolyte is an inorganic salt such as Li C104 and a nonaqueous solvent, W
O3+x L1++χe--+li Due to the reduction reaction of ZWO3, transparent W O3 becomes colored l-i χW O3
). The total amount of charge injected at this time is several I C/'-, and even if the light irradiation is stopped and the display drive voltage to the display electrodes 3 is cut off, the coloring state will be the same as when the drive voltage is applied next and the display drive voltage is cut off. It remains as it is until irradiation is performed.

Therefore, while moving the drawing/erasing head 13 in the horizontal direction of the display panel 1, that is, in the sub-scanning direction, one pitch at a time (the horizontal arrangement pitch of the pixel display section), the display drive voltage is applied to the display electrodes 3, and the drawing An image can be displayed on the entire screen of the display panel 1 by controlling the light emission of the LED 14 of the drawing/erasing head 13 using a signal to display each pixel of the display panel 1 one line in the vertical direction. .

In addition, if you want to erase the display, use the display N from the DC power supply 12.
By applying an erasing drive constant pressure of about 10-odd V to the pole 3 and causing the LED 14 of the drawing/erasing head 13 to emit light based on the erasing signal, the area under the counter electrode 8 facing the colored EC material layer 4 is When the photoconductor layer 7 of W! J6 and the ground line GND through the transparent conductive layer 6, a potential of about -0.6V is generated between the display electrode 3 and the counter electrode 8, and oxidation occurs in the EC material layer 4, which is the opposite of that during coloring. As the reaction occurs, the colored EC material layer 4 is decolored. Note that this decolored state is also maintained as it is until the next application of driving voltage and light irradiation. Therefore, while moving the drawing/erasing head 13 one pitch at a time in the sub-scanning direction, an erasing drive voltage is applied to the display electrode 3, and the light emission of the LED 14 of the drawing/erasing head 13 is controlled by the erasing signal. , by erasing each pixel of the display panel 1 one line at a time in the vertical direction, the image of the entire screen of the display panel 1 can be erased.

Note that this electrochromic display device can also display the next image while erasing the displayed image on the screen. In that case, the drawing/erasing head 13 is moved one pitch at a time in the sub-scanning direction. However, the above-described display erasure and display of the next image may be performed.

That is, in the electrochromic display device, a transparent display electrode 3 is formed on two surfaces of a transparent substrate on the front side, an EC substance 1!4.4 is formed in the shape of a display pixel on the surface of the transparent display electrode 3, and a transparent A transparent conductive layer 6 and a photoconductor layer 7 covering the transparent conductive layer 6 are provided on the substrate surface 5.
Opposing N poles 8.8 facing the EC material layers 4, 4 on top of the EC material layers 4, 4
At the same time, a driving voltage is applied between the display electrode 3 of the front transparent substrate 2 and the transparent conductive layer 6 of the back transparent substrate 5, and on the back side of the back transparent substrate 5,
A display/erasing light source is provided to irradiate light onto portions of the photoconductor layer 7 corresponding to the opposing electrodes 8, 8, and the display electrode 3 on the front transparent substrate 2 and the transparent substrate 5 on the back side are provided with a light source for display/erasing. A driving voltage is applied between the conductive layer 6 and the counter electrode 8.8 is transparently conductive Fi! by light irradiation. ! 6, a potential difference is generated between the display electrode and the counter electrode, so that reduction and oxidation reactions occur in the EC material layer on the surface of the display electrode, and display and erasure can be performed.

In this electrochromic display device, a potential difference is generated between the display electrode 3 and the counter electrode 8.8 by bringing the counter electrodes 8, 8 into electrical conduction with the transparent conductor 16 through light irradiation. , there is no need to apply a voltage to said opposed type 1i8.8 via a lead, and therefore the opposed 'R positive 8.8. Since there is no need to ensure lead wiring spacing between the opposing type lI! By reducing the arrangement interval of the EC material layers 4.8 and correspondingly reducing the arrangement interval of the EC material layers 4.4, it is possible to increase the density of display pixels.

FIG. 2 shows an example in which the above-mentioned electrochromic display device is applied to an electronic whiteboard device, and this electronic whiteboard device includes a display panel 1 of the above-mentioned electrochromic display device.
is used as a writing panel for characters, figures, etc., and a light-shielding cover 16 is provided on the back side of the display panel 1 to prevent disturbance light from hitting the back surface of the display panel. An erasing head 13 is provided so as to be movable laterally along the back surface of the display panel, and a self-propelled arm 17 equipped with a CCD line sensor inside is provided on the front side of the display panel 1 so as to be movable laterally along the surface of the display panel. The structure is as follows. Note that characters etc. to be written on the panel surface may be written directly on the 2 surfaces of the transparent substrate on the front side of the display panel 1, or a transparent sheet that can be written and erased is provided on the surface of the display panel and written on the transparent sheet surface. You may also write it.

This electronic blackboard device uses a self-propelled arm to transfer written images (letters, figures, etc.) written on the panel surface using a felt ben or the like.
In addition to reading and printing out images using the CCD line sensor in The written image written on the panel surface is read by a CCD line sensor, and this read image, that is, a composite image of the displayed image and the written image can be printed out. has the following structure.

That is, FIG. 3 shows the control circuit of the above-mentioned electronic whiteboard device, and this control circuit includes the CPU 20, the key human power section 2
1. Compression/expansion circuit 22, internal RAM 23, printer 25
Print driver 24 that drives printing, drawing/erasing head 1
A motor driver 26 that drives the moving motor 27 of No. 3, and an LE that drives the LED 14 in the drawing/erasing head 13 to emit light.
A D driver 28, a motor driver 29 that drives the travel motor 3o of the self-propelled arm 17, and a CCD in the self-propelled arm 17.
It is composed of a COD driver 31 that drives a line sensor 32, and an external RAM 34 for storing read information such as a RAM card is connected to the CPU 20 via a connector 35.

The operation of the electronic whiteboard device will be explained with reference to this control circuit.The embedded image of glyphs, characters, etc. written on the panel surface is the I? of the self-propelled arm 17. The data are sequentially read line by line by the CCD line sensor 32 in the J-scanning movement a (lateral movement).

In FIG. 3, 33 is a screen illumination light source provided in the self-propelled arm 17, and the reflected light from the panel surface illuminated by the illumination light from this light source 33 is used as a CCD.
It is read by the line sensor 32.

The read information outputted line by line from the CCD line sensor 32 is amplified by the amplifier 36 and
It is sent to the value conversion circuit 37. This 2 (keratinization circuit 37 is C
The read information from the CD line sensor 32, that is, the pixel information for one line, is converted into white and black 21 data corresponding to each pixel.

This binary data is serial/parallel converted by the S/P conversion circuit 38 and sent to the compression/expansion circuit 22 via the CPIJ 20. The compression/decompression circuit 22 compresses and converts this black and white binary data into, for example, a run-length code.
Further, this compressed data is sequentially stored in the internal RAM 23. The data stored in this internal RAM 23 is transferred to the read information storage external RA~134 and stored in this external RAM 34 when a read information storage command is input from the key manual section 21 by button operation. In addition, this external RAM 34 is a backup 7X for memory retention.
When it is desired to store the read information in this external RAM 34, it is installed in the external RAM @ side part of the electronic whiteboard installation.

Furthermore, when a copy command is input from the key manual unit 21 by operating the copy button, the data stored in the internal RAM 23 or the external RA~134 is read line by line and sent to the compression/expansion circuit 22. The data is then expanded and converted into the original black-and-white binary data by the compression/decompression circuit 22, and this black-and-white binary data is sent to the print driver 24, and the printer 25 is driven to print. This printer 25
2 is used to print on print paper based on the monochrome 2 (III data), and a copy printed by the printer 25 is sent to a copy output port.

In addition, if you want to reproduce on the panel the same 8-digit image such as a figure or character written on the panel surface in the past, operate the data designation button of the key manual section 21 to store the data in the internal RAM 23 or Specify data to be read from external RAM 34. When this data is specified, the internal RAM 23
Alternatively, specified data is read from the data in the external RAM 34, expanded by the compression/expansion circuit 22 into original black and white binary data, and sent to the LED driver 28. At this time, the LED of the drawing/erasing head 13
l4 is driven to emit light in accordance with the monochrome 21i data, and a display drive voltage is applied to the display electrodes 3 of the display panel 1, and the drawing/erasing head 13 moves in the sub-scanning direction (lateral movement).
Accordingly, a screen is displayed on the display panel 1. This display image and a composite image of this display image and a written image written on the panel surface are read by the CCD line sensor 32 and stored in the internal RAM 23 in the same manner as described above, and are also stored in the external RAM.
34, it is also stored in this external RAM 34 and printed out by the printer 25. The composite image of the display image and the writing acid is also stored in the internal RAM 23 or external RAM 34, so if this composite image is read from the internal RAM 23 or external RAM 34 and displayed on the display panel 1, the composite image Images can also be reproduced on the panel surface when necessary.

It should be noted that the electrochromic display ii1 can of course be used not only for the above-mentioned electronic blackboard display, but also as a stationary display for computers, word processors, etc., and displays for electronic bulletin boards.

Further, in the above embodiment, the display electrode 3 of the back side transparent substrate 2
The transparent electrodes 11116 and 11116 of the backside transparent substrate 5 are used as full-surface electrodes covering the entire surface of the substrate.
and the transparent conductor 116 may be formed in a simple matrix shape similar to the N pole of a dot matrix liquid crystal display panel. It is also possible to drive the LED 14 to emit light and display by static driving in synchronization with this. Further, in the above embodiment, as a display/erasing light source provided on the back side of the display panel 1, a large number of light emitting elements (LEDs 14) are arranged in a - column, and a drawing movable in a direction perpendicular to the direction in which the light emitting elements are arranged. The display/erasing head 13 is used, but this display/erasing light source may be one in which light emitting elements are arranged in a dot matrix pattern corresponding to all the pixel display areas of the display panel 1, or a dot matrix light source may be used. A matrix liquid crystal shutter may be used to selectively irradiate each pixel display section with light.

Further, although the above embodiments have been described with respect to an electrolyte type electrochromic display device, it goes without saying that the present invention can also be applied to a solid electrolyte type electrochromic display device.

〔Effect of the invention〕

In the electrochromic display 8H of the present invention, a transparent display electrode is formed on the front transparent substrate surface, an EC material layer is formed in the shape of a display pixel on the transparent display electrode surface, and a transparent conductive layer is formed on the back transparent substrate surface. A photoconductor layer is provided to cover the transparent conductive N layer, and a counter electrode facing the EC material layer is formed on the photoconductor layer, and a display electrode on the front transparent substrate and a back transparent substrate are formed on the photoconductor layer. A driving voltage is applied between the photoconductor layer and the transparent conductive layer, and a display/erasing light source is provided on the back side of the backside transparent substrate to irradiate light to a portion of the photoconductor layer corresponding to the counter electrode. , because the counter electrode is electrically connected to the transparent conductive layer by light irradiation, thereby creating a potential difference between the display electrode and the counter RI electrode.
There is no need to apply voltage to the opposing M poles via leads. Therefore, according to the present invention, since it is not necessary to ensure a lead wiring interval between opposing electrodes, the arrangement interval of the opposing electrodes is made small, and the arrangement interval of the EC material layer is also made small correspondingly. The pixel density can be increased.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a portion of an electrochromic display device showing an embodiment of the present invention, and FIGS. 2 and 3 are perspective views of an electronic whiteboard device using the electrochromic display device and a block diagram of its control circuit. It is. 1... Display panel, 2... Front side transparent substrate, 3...
- Transparent display N pole, 4... EC material layer, 5... Back side transparent substrate, 6... Transparent conductive layer, 7... Photoconductive pair layer,
8... Counter electrode, 9... Insulating partition material, 10...
Electrolytic solution, 11...Background material, 13...Drawing/erasing head, 14...Light emitting diode, 15...Lens system. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (2)

[Claims] (1) In an electrochromic display device that uses an electrochromic substance that colors/discolors through reduction/oxidation reactions caused by the application of voltage, a transparent display electrode is formed on the front transparent substrate surface, and an EC substance is applied to the transparent display electrode surface. A layer is formed in the shape of a display pixel, and a transparent conductive layer and a photoconductor layer covering the transparent conductive layer are provided on the front side transparent substrate surface, and an opposing layer facing the EC material layer is provided on the photoconductor layer. At the same time as forming an electrode, a driving voltage is applied between the display electrode on the front side transparent substrate and the transparent conductive layer on the back side transparent substrate, and the photoconductor layer is applied on the back side of the back side transparent substrate. An electrochromic display device comprising a display/erasing light source that irradiates light onto a portion corresponding to a counter electrode. (2) The electrochromic material layer and the counter electrode are arranged in a dot matrix, and the display/erasing light source has a large number of light emitting elements arranged in a row corresponding to the arrangement pitch of the counter electrode. 2. The electrochromic display device according to claim 1, further comprising a drawing/erasing head movable in a direction perpendicular to the direction in which the light emitting elements are arranged.