JP2001188487A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device which can make high-grade image display with low electric power consumption and can constitute a system dealing with the network. SOLUTION: An endlessly spread translucent sheet 10 is subjected to color image recording of an ink jet recording system by a recording head unit 20. A display section 33 of an electrophotographic recording system is arranged on the rear surface of the sheet 10 in a display section 3 and is subjected to image recording of black characters, etc. As a result, the color images by the sheet 10 and the images of the black characters, etc., transmitted through the sheet 10 may be displayed in the display section 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device capable of displaying an image sent from a host computer.

[0002]

2. Description of the Related Art Generally, image display devices include devices mainly for displaying moving images, such as CRTs and liquid crystal displays, which are display devices such as computers. On the other hand, there is a display device which repeatedly displays and deletes a large screen still image like a poster or a bulletin board. An example of this display device is an information board that displays destinations and information in a station yard. Further, as a similar device, there is an electronic blackboard used for a meeting, a meeting, or the like.

In recent years, an increase in paper consumption and an increase in power consumption for image display have become problems in terms of resource saving and environmental destruction. In order to solve these problems, there is a demand for the latter still image display device which consumes less power and drastically reduces paper consumption.

[0004] Conventional CRTs and liquid crystal displays, which are moving picture display devices, have a problem that as the size increases, the device price increases. Further, since power is used to maintain a display state even when a still image is displayed for a long time, there are many problems in terms of power consumption. Recently, many large and low power consumption type display devices such as plasma displays (PDPs) have been developed and commercialized.
This is a display device that considers moving image display like RT, and is not suitable for long-time display of a still image.

[0005] As a display device for recording and erasing a still image display on the same medium, an information board that records an electrostatic latent image corresponding to an image signal from a computer or the like on a special medium, develops the image with magnetic toner, and displays the image. Has been commercialized. If the electrostatic image on the medium is removed, the image adhered and developed on the special medium is removed, and a new image can be repeatedly recorded and displayed. The only problem with this information board is that it is difficult to colorize using magnetic toner.

On the other hand, although the method of use and purpose are different from those of the above-mentioned display device, a still image (characters) which is hand-written is displayed, and the displayed content is read by a scanner to obtain a hard copy. There is an electronic blackboard device as a device for erasing a blackboard with a blackboard eraser. This device is useful in terms of reducing paper consumption and power consumption. However, there is currently no product that is connected to a computer or the like to record and display a still image and to automatically erase a written image. The development of an electronic blackboard device with an image erasing function has been conventionally performed. For example, JP-A-61-9071, JP-A-5-597, JP-A-5-14564, and JP-A-5-160940. JP-A-5-162494, JP-A-6-320
No. 95, JP-A-6-48091, JP-A-6-48091
No. 87295 and JP-A-6-245008 have been proposed. According to the invention described in the above publication, characters and images handwritten on a medium of a conventional electronic blackboard by a writing instrument for an electronic blackboard can be applied to an electrophotographic photosensitive member cleaning apparatus used in a copying machine such as a cleaning fur brush or a rubber blade. An apparatus for wiping and erasing by a similar method has been proposed. However, with respect to the image writing unit, only the handwriting is performed with a writing instrument as in the related art.

The requirements for a still image information display device are as follows:
It not only exists as a stand-alone device in a conference room like an electronic blackboard, but also has a function as a display device in a network, and can display information from a remote place sequentially. It is hoped that it can be displayed on

In a conventional image display device, a device capable of performing writing and erasing based on information from an external image input device is a magnetic recording system (also referred to as an electrophotographic recording system).
Information board only. However, colorization is difficult due to the use of magnetic toner,
An image display device capable of displaying a color image and recording and displaying a high-quality image has been desired.

Accordingly, the present applicant has mounted an ink jet recording apparatus on a recording medium similar to an electronic blackboard as a system capable of displaying a color image, writes an image on the medium, displays the image, and performs the above-described erasing method. A prototype of an image recording and display device capable of erasing images was studied.

In the ink jet recording system, recording is performed by flying small ink droplets and attaching the ink to a recording medium such as paper.

When ink-jet recording is performed on a recording medium similar to a conventional electronic blackboard, it has been impossible to write and record with conventional ink-jet inks. Generally, as a recording medium used for an electronic blackboard, a sheet in which a fluorine compound-based film or the like is stuck on a milky white base film is used. With a blackboard pen using water-based ink, when an image is written on a blackboard, a resin film containing a release agent and a pigment remains after the moisture evaporates, and thus can be easily wiped and erased with a cloth, felt, sponge, or the like. . In addition, the surface tension of the recording medium is set small so as to facilitate erasing. Therefore, there is a problem that when recording is performed with ink jet ink, the ink is repelled on a conventional recording medium and image recording cannot be performed. Further, if the surface tension of the recording medium is made larger than that of the conventional one, there has been a problem that an erasing device such as a blade cannot perform sufficient erasing.

[0012] Inks used in the ink jet recording system are classified into aqueous and non-aqueous. Generally, the aqueous system contains water as a main component and contains a water-soluble high-boiling solvent such as glycol for the purpose of preventing drying and preventing nozzle clogging.

In an aqueous system, prior to ink ejection,
There has been proposed a method in which a liquid for improving an image is attached to a recording medium in advance. In particular, an improvement in fixability has been observed by recording a liquid containing an organic compound having a cationic group onto a recording medium and then recording with an ink containing an anionic dye.

As a method other than using an ink set combining a treatment liquid containing the above-mentioned cationic substance, a method using an adhesive ink set has been proposed. Examples of the adhesive ink set include aqueous inks containing pigments, resin dispersants, adhesive polymer emulsions, glycols, and the like. This ink has a low viscosity in a dispersed state before being discharged, and after being discharged, is aggregated and formed into a film and fixed.

[0015] If the ink is non-aqueous, the same quick-drying ink as the conventional marker pen for whiteboard can be used, so that the fixing property and the peeling property are improved. Examples of the non-aqueous solvent used in the non-aqueous inkjet ink include hydrocarbons (such as liquid paraffin), alcohols (such as methyl alcohol, ethyl alcohol, and propyl alcohol), phenols, pyrrolidones, and ester solvents. Can be

If the quick-drying property is too high, the ink density will increase before ejection, causing problems such as nozzle clogging. Examples of non-aqueous solvents with slightly reduced drying properties include, for example, alkyl ethers of (mono, di, tri, tetra) alkylene glycols, for example, ethylene glycol monoalkyl ether, diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, propylene glycol Acetates of the alkyl ethers of the aforementioned alkylene glycols, such as monoalkyl ethers, tripropylene glycol monoalkyl ethers and alkylene glycols, and pyrrolidones such as 2-pyrrolidone, N-
Methylpyrrolidone and mixtures thereof can be mentioned.

A device capable of performing writing and erasing based on information from a conventional external image input device for a monochrome image only includes a magnetic recording type information board. Connect this online, record it on your computer,
There was a system to erase.

[0018]

As described above, in the conventional image display device, since the magnetic toner is used, it is difficult to colorize the image, and it is possible to display a color image and to record and display a high quality image. An image display device has been desired.

On the other hand, it is possible to display a full-color image by a plasma display, but it is difficult to see it in a bright place such as outdoors during the daytime. Further, even when a still image is displayed, power is consumed and energy is wasted. There were many problems. The liquid crystal has problems such as a low contrast, a viewing angle characteristic, and a relatively large power consumption for holding a display due to the necessity of a backlight or lack of memory.

When a recording medium having a receiving layer in an ink jet recording system is used as an electronic blackboard, it is difficult to reuse the recording medium, and the ink and the recording medium become consumables, and cost and cost are reduced.
Maintenance and ecology problems occur.

In order to reuse a recording medium, it is necessary to achieve both the fixing property to the recording medium without the receiving layer and the peeling property from the recording medium. That is, it is necessary to provide a configuration that prevents the recorded image from bleeding because the solvent in the ink exists on the surface of the recording medium and has fluidity. Furthermore, it is necessary that images can be easily and completely erased. JP-A-8-106
No. 261 and Japanese Patent Application Laid-Open No. H8-310078 do not solve this problem.

The present invention has been made under such a circumstance. By using a reusable magnetic toner for a black character portion most frequently used in an information board, low power consumption and resource saving can be achieved. It is an object of the present invention to provide an image display device which can provide a high-quality color image display by using an ink jet system for a color image portion which has been difficult with a conventional magnetic toner system, and can further form a network-compatible system. Is what you do.

[0023]

In order to achieve the above object, according to the present invention, an image display device is configured as described in the following (1) to (5).

(1) First image display means for displaying a monochrome image, and second image display for displaying a color image on a recording member on a transparent recording member on a display portion of the first image display means. Image display device comprising:

(2) In the image display device described in (1), the first image display means is of an electrophotographic recording type, and the second image display means is of an ink jet recording type. Display device.

(3) In the image display device described in (2), the second image display means includes two rollers arranged at an interval and an endless stretch between the two rollers. An image display device, comprising: a light-transmitting sheet provided thereon; and a recording head that discharges a processing liquid and ink onto the sheet. The first image display unit is disposed on a back surface of the sheet.

(4) In the image display device according to any one of (1) to (3), the first image display means and the second image display means are input from a host computer via a line. Image display device for displaying the obtained data.

(5) In the image display device described in (3), the treatment liquid contains a cationic substance and finely divided cellulose, and the ink is a dye ink containing a water-soluble dye containing an anionic group or an anionic ink. An image display device which is a pigment ink containing a compound and a pigment.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples of an image display device.

[0030]

(Embodiment 1) FIG. 1 is a schematic front view of an "image display device" of Embodiment 1, and FIG. 2 is a schematic side sectional view. The image display device includes an image writing unit 1, a recording medium driving unit 2, a display unit 3, and an image erasing unit 4. The recording medium 10 (hereinafter referred to as a sheet) is stretched endlessly by rollers 11 and 12 rotatably supported on a housing side plate (not shown). 13 and 14 are roller shafts of the respective rollers. The sheet drive unit 15 has a built-in stepping motor, transmits drive to the roller shaft 14, and drives the sheet 10.

The image writing unit 1 includes a recording head unit 2
0 and a carriage 21 on which it is mounted, and two guide shafts, a guide shaft 22 and a guide shaft 23.

FIG. 3 is a detailed schematic diagram of the image writing unit, and FIG. 4 is a schematic diagram of the front surface of the recording head. Carriage 21
Is configured to be movable in a direction determined by the two guide shafts 22 and 23, and reciprocally scans a recording area on the sheet 10. On the carriage 21, a recording head unit 20 including a recording head group 24 for discharging a plurality of color inks and processing liquids, and an ink tank 25 for supplying ink and processing liquid to each recording head 24 is mounted. The plurality of color inks mounted on this image display device are four colors of black (Bk), cyan (C), magenta (M), and yellow (Y). A recovery system unit 26 is provided at the lower right of the front right end (see FIG. 1) of the area where the carriage 21 can move.
An ink suction unit and a wiping unit for capping the discharge unit with a cap member (not shown) and for cleaning the nozzle 27 or the vicinity of the nozzle of the recording head 24 are mounted. Usually, the position where the recording unit 20 is located on the recovery system unit 26 is called the home position of the recording head 24. The print head unit 20 includes a print head group 2 that discharges black (Bk), cyan (C), magenta (M), and yellow (Y) color inks and a processing liquid.
4, a processing liquid tank 25a and a Bk tank 25b, C
Tank 25c, M tank 25d, Y tank 25e
Is mounted. Each tank is connected to the print head group 24 via a connection portion of the print head group 24, and supplies ink and a processing liquid to the ejection ports.

FIG. 4 shows the front surface of the recording head group 24. The recording head group 24 is composed of heads 24a for discharging the processing liquid, and heads for discharging the black 24b, cyan 24c, magenta 24d, and yellow 24e. Each head is held by the recording unit 20. . Each head has 256 nozzles 27 each
It is composed of

Here, the treatment liquid in this embodiment will be described in detail. The treatment liquid is a treatment liquid containing at least a cationic substance, and further contains finely ground cellulose. The function of the processing liquid containing a cationic substance at the time of image formation will be described below. Incidentally, for simplicity of description, a case where recording is performed using a dye ink containing a water-soluble dye containing an anionic group will be described, but using a pigment ink containing an anionic compound and a pigment. The same applies to recording. The treatment liquid contains an anionic compound, for example, when used with an ink containing a dye as a coloring material, when mixed with the ink on a sheet, the first step of the reaction is the cationic liquid contained in the treatment liquid. The low molecular weight component of the substance and the anionic compound in the ink are associated by ionic interaction, and the dye in the ink is instantaneously aggregated and separated from the solution phase.
Next, as a second step of the reaction, an aggregate of an anionic compound and a low molecular weight cationic substance is adsorbed by finely ground cellulose (preferably having an average particle size of 5.0 μm or less) contained in the treatment liquid. The size of the aggregates of the dyes formed in the above-mentioned association is further increased, so that
Solid-liquid separation. In this state, the liquid portion has a role of a portion to be fixed on the sheet, and has a feature that the image is easily erased, which will be described in detail later.

Further, the aggregate formed by the low molecular weight component of the cationic substance, the anionic dye and the finely ground cellulose not only satisfies the condition for fixing the sheet appropriately on the sheet due to the increase in viscosity, but also The image does not flow due to the dripping of the image on the sheet. Further, migration does not occur due to being left for a long time, and even if adjacent dots are formed of different colors of ink, the dots do not intermingle, and the phenomenon of bleeding (bleeding) of ink at the boundary surface of a different color image does not occur.

That is, it is possible to form a high-quality image that can be erased and does not cause migration, bleeding, or dripping on a sheet, which cannot be achieved with a commonly used ink-jet ink.

Regarding cationic substances, finely divided cellulose, and other additives and inks containing an anionic group corresponding to the processing liquid contained in the processing liquid, see JP-A-8-7239.
As described in detail in Japanese Patent Publication No. 3
What is necessary is just to use the ink set of an ink and a processing liquid.

Next, the sheet 10 on which a color image is written by the writing section 1 will be described.

In the apparatus of this embodiment, as the sheet surface material on which the best writing and erasing can be performed with the ink set, polyethylene terephthalate (PET), polyethylene, polyacryl, polyvinylidene fluoride, polyethylene-methyl methacrylate copolymer ( EMM
A). Further, among the sheets considered for erasing, a sheet having a porous shape in which the dye penetrates into the sheet surface is not suitable for the present image display device, and a sheet having a smooth surface is suitable for writing / erasing. Was.

The image display unit 3 will be described. The images sequentially written by the image writing unit 1 are conveyed in the direction of arrow A in FIG. When the desired image has been written, the image is displayed at an appropriate display position on the image display unit 3. An electrophotographic recording display unit 33 is provided on the back surface of the sheet 20, and also serves as a support plate so that the sheet 20 does not loosen. At this display position on the sheet 20, it is possible to additionally write with the electronic blackboard pen.

Next, the image erasing section 4 will be described. FIG. 5 is a schematic diagram showing details of the image erasing section 4. The image erasing unit 4
A detachable blade 40 for wiping and erasing ink on the sheet 10, a blade support plate 41, a waste ink reservoir 42 for accumulating and accumulating the erased ink, and a sheet cleaning for further improving the cleaning on the sheet A roller 43 and a cleaning roller shaft 44 are provided.

The blade separating / contacting means is a plate-like blade 4 made of an elastic material such as urethane rubber and having substantially the same width as a sheet.
0, a blade support plate 41 on which the blade 40 is mounted, a blade support plate rotating means 45, a tension spring 46 and a solenoid 47. Blade support plate rotating means 45
The pivot shaft 49, the connecting rod 50, and the blade supporting plate 41 are fixed to the supporting plate 48, and the plunger 51 connected to the solenoid 47 is fixed to the center of the connecting rod 50. The rotation shaft 49 is rotatably supported by a frame (not shown).
The solenoid 47 is fixed to a frame (not shown), and the plunger 51 is rotatably attached to the center of the connecting rod 50. One end of the tension spring 46 is attached to a part of the support plate 48, and the other end is attached to a frame (not shown). As a result, the blade 40 rotates by the biasing and non-biasing of the solenoid,
Moves away from the sheet 10.

The cleaning roller 43 is made of polyurethane sponge or the like, and is composed of a cylindrical porous roller 43 and a roller shaft 44 substantially equal in width to the sheet 10, and is supported by a frame (not shown) to be rotatable. It has become. The roller 43 is driven by the sheet driving roller 12.
When the erasure is incomplete with the blade 40, it is completely removed by being rotated from the driving unit 2 for driving the sheet 10 so as to be opposed to the traveling direction A of the sheet 10 (counter direction). is there.

According to the above-described configuration, when an image is formed on a sheet by ink-jet recording and the image is displayed, the created image can be erased as necessary.

A display / operation panel for directly giving instructions to the apparatus and for displaying the state of the apparatus on a monitor is provided below the display section in FIG.

Next, the configuration and operation of the image display device of this embodiment will be described.

FIG. 6 is a block diagram showing the configuration of this embodiment. Character or image data to be recorded (hereinafter, referred to as image data) is input from the host computer 100 to the reception buffer 101 of the image display device. Further, data for confirming whether or not data is correctly transferred, data for notifying the operation state of the image display device, and the like are returned from the image display device to the host computer 100. The data in the reception buffer 101 is transferred to the memory unit 103 under the control of a control unit 102 having a CPU, and is transferred to a RAM (Rand).
om Accesses Memory). The mechanical control unit 104 drives a mechanical unit 105 such as a carriage motor or a sheet feed stepping motor according to a command from the control unit 102. The sensor / switch control unit 106 sends a signal from the sensor / switch unit 107 including various sensors and switches to the control unit 102. Display element control unit 108
Is the LE of the display panel group according to a command from the control unit 102.
D, a liquid crystal display element and the like, and a display element section 109 which is a recording display section of an electrophotographic system. The recording head control unit 110 controls the recording head 111 according to a command from the control unit 102. Further, temperature information indicating the state of the recording head 111 is sensed and transmitted to the control unit 102.

The image processing unit 112 processes the image data input to the receiving buffer 101 and generates data for recording. The original data is stored in the image processing unit 112.
The black character portion is recorded in the same manner as the so-called electrophotographic information board, in which an electrostatic latent image is recorded on a special medium, developed with magnetic toner, and displayed. Colored characters and image portions are formed on a transparent medium (thickness 12
EMMA 50μm on 5μm polyester film
Record). The recorded images are displayed with their positions adjusted.

In the case of an image having only a black character portion or an image having only a color character or an image portion, recording is performed on a single display portion, and blank data is sent to another display portion.

The operation of recording, displaying, and erasing color characters and image portions using the image display apparatus will be described in order with reference to the flowchart of FIG.

When the power is turned on by turning on a device switch (not shown) (see S1, the same applies hereinafter), the sheet drive motor of the drive unit 2 is operated (S2), and the sheet 10 is fed in the direction of arrow A in FIG. Marker 60 provided at the end of sheet 10
Is detected by the sensor 61 (S3), the sheet 10 stops (S4). After releasing the recovery system cap of the recovery system unit 26, the image writing unit 1 detects the home position of the head unit 20. After detecting the head home position, the recovery system unit 26 performs an initial operation of the recording head 24 by sucking ink from the head 24 or wiping operation (S5). When the initial operation is completed, the process waits for a recording signal (S6). The erasing unit 4 confirms that the sheet 10 has completed the initial operation and has stopped, and sends a signal to the solenoid 47 so as to bring the blade 40 into contact with the sheet 20 (S7). When the above-mentioned operation is completed, the writing is ready.

The host computer 100 corrects the image to be displayed to the size of the sheet 10, and transmits an image signal. At this time, unlike a normal printer, image development is performed so that a signal is sent to the recording head unit 20 so that printing is performed from below the image so that the image can be observed from the front of the apparatus. When the recording signal is sent to the recording head group 24,
Cyan, magenta, and yellow inks and a colorless processing liquid are ejected from each recording head. Further, prior to the ejection of the recording ink, the treatment liquid is ejected and adhered to at least a portion where the recording ink of each color adheres to the sheet. In the present embodiment, the recording head group 24 is composed of five recording heads. However, the present invention is not limited to this. Is also good. In addition, the present invention is not limited to the head arrangement of the present embodiment.
The number can be freely selected.

The recording head 24 performs recording along the guide shafts 22 and 23, and the sheet 10 is fed stepwise according to the width of the recording head for each reciprocation. When the recording of the image on the display area is completed (S9), the recording head 24 returns to the home position, performs a cleaning operation by the recovery unit 26, and the recording head 24 is capped by the cap unit.

Next, the previous image is deleted to display a new image. The erasing method includes a mode for erasing a previously recorded image simultaneously with recording by the recording head 24,
It has a mode only for erasing the recorded image, but this selection can be made by instructing the host computer 100. In the mode of only erasing, the erasing mode can be selected from the display / operation panel 52 attached to the exterior of the apparatus (not shown). It is determined whether the printing is completed (S12).
Returning to step 5, the printing operation is repeated, and when it is completed, the power is turned off (S13), and the flow ends.

As a recording medium, an EMMA resin having an ethylene content of 90 Wt% and a weight average molecular weight of 200,000 was used. After forming a sheet of this resin, a laminated sheet was formed by bonding the sheet to a transparent base film (PET). This sheet was set as a recording medium in the image display device shown in FIG. The sheet width used was 50 cm. The total light transmittance of this sheet was 78%.

Next, the following liquid composition (treatment liquid) A
And Ink B were prepared.

Components of Liquid Composition A First, the following components were mixed and dissolved, and then pressure-filtered through a membrane filter having a pore size of 0.22 μm (trade name: Fluoropore Filter, manufactured by Sumitomo Electric Industries, Ltd.). 4.
The liquid composition A adjusted to 8 was obtained.

・ Benzyl tri-n-butylammonium chloride (molecular weight: 311) 5.0 parts ・ Ceolas cream (3.5 μm average particle size) [Asahi Kasei Microcrystalline Cellulose, 10% slurry] 10.0 parts ・ Diethylene glycol 10 0.0 parts ・ Ion-exchanged water 75.0 parts Preparation of ink B Next, the following components were mixed, and the pore size was further reduced to 0.22.
The solution was filtered under pressure through a μm membrane filter (trade name: Fluoropore Filter, manufactured by Sumitomo Electric Industries, Ltd.), and yellow, magenta, cyan, and the like containing a dye containing an anionic group whose pH was adjusted to 4.8 were prepared. Black ink Y1,
M1, C1, and B1 were obtained. Y1, M1, C1 and B
1 was designated as ink B.

(Yellow Ink Y1) C.I. I. Direct Yellow 86 2 parts-Thiodiglycol 10 parts-Acetyleneol EH 0.05 parts-Ion exchange water 87.95 parts (Magenta Ink M1)-C.I. I. Acid Red 289 2.5 parts ・ Thiodiglycol 10 parts ・ Acetyleneol EH 0.05 part ・ Ion exchange water 87.45 parts (cyan ink C1) ・ C.I. I. Acid Blue 9 2.5 parts-Thiodiglycol 10 parts-Acetyleneol EH 0.05 parts-Ion exchange water 87.45 parts (black ink B1)-C.I. I. Food Black 2 4.0 parts • Thiodiglycol 10 parts • Acetyleneol EH 0.05 parts • Ion-exchanged water 85.95 parts Using liquid composition A and ink B of the present example obtained as described above. An ink set was formed, and image recording and erasing were performed using the image display device shown in FIG.

For displaying a monochrome image, a Canon information board was mounted at a position 33 in FIG. 2 to display an image.

A full-color image can be displayed.
0.2k power required to display one image for one hour
wh or less.

As described above, according to this embodiment,
A high-quality color image can be displayed with low power consumption, and a system compatible with a network can be configured.

Example 2 In addition to using an ink set combining the treatment liquid containing a cationic substance disclosed in Example 1, an adhesive ink set can also be used. Hereinafter, this example will be described as a second embodiment.

A. Black ink (preparation of pigment dispersion) Styrene-acrylic acid-butyl acrylate copolymer 1.5 parts (acid value 116, weight average molecular weight 3700) monoethanolamine 1 part ion-exchange water 81.5 parts diethylene glycol 5 parts Mix the ingredients, warm to 70 ° C in a water bath,
Dissolve the resin completely. Carbon black (MCF88 manufactured by Mitsubishi Kasei) 10 newly produced in this solution
And 1 part of isopropyl alcohol, and after premixing for 30 minutes, dispersion treatment was performed under the following conditions.

Disperser Sand glider (made by Igarashi Kikai) Pulverization media Zirconium beads 1 mm diameter Filling rate of pulverization media 50% (volume) Pulverization time 3 hours Further centrifugation (12000 PRM, 20 minutes) is performed to remove coarse particles. To obtain a dispersion.

Preparation of ink 10 parts of the above dispersion 10 parts Teisan resin 370N 0.1 part Diethylene glycol 15 parts N-methylpyrrolidone 5 parts Isopropyl alcohol 3 parts Deionized water 65 parts The above components were mixed, and the pH was adjusted from monoethanolamine 8 Adjusted to 10 and further, as a surfactant,

[0067]

Embedded image (N + m = 20, p = 5, k = 20, molecular weight about 2500
(50% methanol solution of the above compound) to adjust the surface tension to obtain a black ink.

B. Yellow ink In the above formulation, the pigment carbon black was replaced with C.I. I. P
A yellow ink was prepared in the same manner except that the yellow ink 13 was used.

C. Magenta ink In the above formulation, the pigment carbon black was replaced with C.I. I. P
A magenta ink was prepared in the same manner except that the red ink was used as the red ink.

D. Cyan ink In the above formulation, the pigment carbon black was replaced with C.I. I. P
Cyan ink was prepared in the same manner except that the blue ink was used.

In this embodiment, a white PET film containing titanium oxide as a belt-shaped recording medium had a critical surface tension γ _{C at} 25 ° C. of 45 dyne · cm ⁻¹ .

The surface tension γ _{L at} 25 ° C. of the ink prepared above is

[0073]

[Table 1] Met.

Using an ink jet cartridge of Canon BJF-8500 (trade name) and cartridge scanning means, an electronic blackboard device for carrying out printing and recording while carrying a belt-shaped recording medium between two rollers and rotating the rollers was produced.

When printing was carried out using the above-mentioned ink, good printing results were obtained for both characters and pictures, and it was possible to completely erase only the printing portion by ink jet using a commercially available marker pane laser.

[0076]

As described above, according to the present invention,
A high-quality color image can be displayed with low power consumption, and a network-compatible system can be configured.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment.

FIG. 2 is a side sectional view of the embodiment.

FIG. 3 is a detailed view of an image writing unit.

FIG. 4 is a diagram showing a front surface of a recording head.

FIG. 5 is a diagram showing details of an erasing unit;

FIG. 6 is a block diagram showing the configuration of an embodiment.

FIG. 7 is a flowchart showing the operation of the embodiment.

[Explanation of symbols]

 3 display unit 10 sheet (recording medium) 33 display unit of electrophotographic recording system

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Claims (5)

[Claims] A first image display unit for displaying a black-and-white image; and a second image display unit for displaying a color image on a transparent recording member on a display unit of the first image display unit. An image display device, characterized in that: 2. The image display device according to claim 1, wherein
The image display device according to claim 1, wherein the first image display means is based on an electrophotographic recording method, and the second image display means is based on an ink jet recording method. 3. The image display device according to claim 2, wherein
The second image display means includes two image display units arranged at intervals.
A plurality of rollers, a translucent sheet stretched endlessly between the two rollers, and a recording head for discharging a processing liquid and ink onto the sheet. And an image display device disposed on a back surface of the sheet. 4. The image display device according to claim 1, wherein said first image display means and said second image display means are data input from a host computer via a line. An image display device characterized by displaying: 5. The image display device according to claim 3, wherein
Wherein the treatment liquid contains a cationic substance and finely ground cellulose, and the ink is a dye ink containing a water-soluble dye containing an anionic group or a pigment ink containing an anionic compound and a pigment. apparatus.