JP2897450B2 - Electrostatic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrostatic recording medium suitable for use in a display device generally called an electronic blackboard (actually, a whiteboard).

[0002]

2. Description of the Related Art Heretofore, there has been known an electronic blackboard having a function of hard-copying characters handwritten on a blackboard (whiteboard). With this electronic blackboard, if you make a draft on paper, you need to copy it by hand again on the blackboard, and even if you can print that screen,
Once I erased the record on the board, the next time I wanted this record on the board, I had to handwrite it again.

On the other hand, the present applicant has previously proposed an electronic blackboard having a display function capable of reading original information, writing the information on a blackboard sheet and displaying the blackboard sheet (Japanese Patent Laid-Open No. 64-96).
No. 6 publication).

As shown in FIG. 6, the electronic blackboard with a display function is provided such that an electrostatic recording medium 1 as a blackboard board can be transferred endlessly via a feed motor 2 and a driving roller 3.

As shown in FIG. 7, a film-like conductive layer 2 is formed on a flexible sheet-like base 21 made of, for example, vinyl chloride by an adhesive 22 as shown in FIG.
3 is adhered, and a film-like dielectric layer 25 is adhered on this via an adhesive 24. Further, as shown in FIG. 8, a hard coat 2 is formed on the surface of the dielectric layer 25 to improve the durability.
6 has been proposed, but some proposals have been made.

The recording medium 1 arranged endlessly
On the back side of the recording head, a recording head 4 composed of writing electrodes, that is, a large number of stylus electrodes 5 and control electrodes 6,
With a cleaning blade 8 and a lens system 9
A CD line sensor 10, a reflection mirror 11, and a developing unit 12 for supplying toner are provided.

[0007] As shown in FIG. 9, the external appearance of the electronic blackboard is entirely covered with a cover 13, and the electrostatic recording medium 1 exposed from a window 13 a on the front surface of the cover 13 functions as a writing board.

The lower portion of the front surface of the cover 13 has a document insertion port 14, a discharge port 15, and a printout discharge port 16 for writing contents.

When this apparatus is used as an electronic blackboard, writing is performed on the writing surface W of the recording medium 1 with, for example, a felt pen or the like.

When copying this, the recording medium 1 is transported, and as shown in FIG. 6, information written on the recording medium 1 on the back side of the apparatus is reflected by a reflection mirror 11 and a lens system.
The image is read by the CCD line sensor 10 through the line 9 . Then, the image is copied on a predetermined recording paper by a xerography method or the like, and is taken out from the outlet 16.

Next, when an image is displayed by electrostatic recording, an electrostatic latent image is recorded on the writing surface W of the recording medium 1 by the recording head 4, and black toner from the developing device 12 is transferred while the recording medium 1 is being transported. Is charged on the electrostatic latent image portion to make a visible image appear.

Thereafter, the cleaning blade 8 wipes off the toner, marker pigment written with a felt pen, ie, ink, etc., and then removes the charge by the AC neutralizer 7.

[0013] recording head 4, the shown the schematic front view, arranged to face the surface before contact with the stylus electrode 5 serving as the recording electrode and the control electrode 6 transgressions electrostatic recording medium body pairs 10 You.

The control electrode 6 is, for example, a pair of control electrodes C ₁ C
₁ , C ₂ C ₂ , C ₃ C ₃ } are arranged.

The stylus electrode 5 includes a pair of control electrodes C _1.
And between C _1, between C ₂ and C _2, a plurality for each pair of electrodes between C ₃ and C ₃ ‥‥, in the illustrated example formed by five increments sequence.

These stylus electrode 5 and control electrode 6
Employs a so-called printed wiring board configuration.

That is, for example, a copper foil is stuck on a so-called epoxy glass substrate in which glass fiber is impregnated with an epoxy resin, and this is selectively etched by photolithography to form a stylus electrode 5 with a required arrangement pattern and control. The electrodes 6 are formed at the same time.

Therefore, the stylus electrode 5 having such a configuration has a plate electrode configuration with a very small area, though it is a stylus-like (needle) shape. Then, as shown in FIG. 11, for example, every other control electrode C ₁ , C ₃ , C _{5 3} , C ₂ , C ₄ , C ₄
Each of the stylus electrodes corresponding to ₆ ‥‥ is grouped into an A series and a B series, and a recording voltage of a predetermined positive pulse voltage is applied to each of the A series and the B series according to recording information. .

The recording head 4 controls the electrostatic recording medium 1
For example, to record an electrostatic latent image on the control electrode C ₁ , C ₃ , C ₅ } corresponding to the A-series, a negative pulse voltage is applied in a time-division manner, and the corresponding A-series is applied. A recording voltage selected according to the recording information, for example, a positive pulse voltage is applied to the stylus electrode 5 of FIG.

Thus, a discharge path is formed between the selected stylus electrode 5 to which the required voltage is applied and the control electrode 6 through the conductive layer 23 through the dielectric layer 25, thereby forming a dielectric path. The gas ions resulting from the discharge remain in the layer 25, whereby recording is performed using an electrostatic latent image. Then, toner is electrostatically adhered to the electrostatic latent image to produce a visible image.

However, when such an electrostatic recording method is employed, a visible image formed by attaching toner to an electrostatic latent image formed on the electrostatic recording medium 1 and having a low contrast becomes an image. This is due to the occurrence of a hollow phenomenon in recording dots. That is, for example, when a square recording dot having one side of 0.375 mm is formed, FIG.
As shown in FIG. 2, even when toner adheres to the periphery, a toner non-adhered portion 27 occurs at the center.

The inventor of the present invention has found that this hollowing-out phenomenon is caused by a problem in the structure of the above-mentioned electrostatic recording medium and caused by a contact state between the recording electrode, that is, the stylus electrode 5 and the electrostatic recording medium 1. I found out. That is, as described above, the formation of the electrostatic latent image is generated by generating an aerial discharge between the stylus electrode 5 and the electrostatic recording medium 1. It is necessary to generate an appropriate gap between the electrode and the medium 1. However, when the above-described electrostatic recording medium is used, as shown in FIG. It has been found that a gap is generated and a discharge is generated, but the center is in a condition where it is difficult to effectively generate a discharge.

[0023]

SUMMARY OF THE INVENTION An object of the present invention is to provide a visible image having a high density, that is, a high contrast, without any missing dots in recording dots.

[0024]

According to the present invention, a sheet-like base 21, a conductive layer 23 formed on the base 21 and a conductive layer 23 formed on the base 21 are shown in FIG. Although the configuration using the dielectric layer 25 is adopted, in particular, the dielectric layer 25 is coated with a hard coat layer 36 having a surface roughness of 5 to 30 μm in which dielectric beads 37 are dispersed.

Numeral 31 indicates the electrostatic recording medium according to the present invention as a whole.

[0026]

The recording of the electrostatic recording medium 31 according to the present invention is performed by the recording method similar to that described with reference to FIG. 6, FIG. 9, FIG. 10 and FIG. Then, a hard coat layer 36 in which dielectric beads 37 were dispersed was provided on the surface to positively roughen the surface. When an electrostatic latent image was formed on the hard coat layer 36, the recording electrode That is, since an appropriate minute gap is generated even in the central portion of the stylus electrode 5, the recording dot is uniformly accumulated with the electrostatic charge over the entire area.
Therefore, when the latent image is made visible by attaching toner, a clear image with high density and high contrast can be displayed.

[0027]

FIG. 1 shows an example of an electrostatic recording medium 31 according to the present invention.
This will be described with reference to FIG. In this case, for example, the adhesive 2 is placed on a sheet-like base 21 made of polyethylene terephthalate.
2, the film-like dielectric layer 23 is adhered. The conductive layer 23 can be formed of a conductive layer having a thickness of, for example, 50 μm, such as polyurethane containing a conductive metal oxide such as titanium oxide or indium oxide.

[0028] Then on the conductive layer 23, for example, dielectric thickness 25μm consisting with an adhesive 24 for example port <br/> Li vinylidenefluoride transparent containing ultraviolet screening agent layer 25
To adhere.

Further, a hard coat 36 in which dielectric beads 37 such as plastic beads and ceramic beads having an average particle diameter of 5 to 30 μm are dispersed on an ultraviolet-curing acrylic resin is applied thereon. At this time, the surface roughness, that is, the depth from the top to the bottom of the unevenness is 5 to 20 μm
Projections can be formed.

Example 1 In the above-described structure, the hard coat layer 36 was composed mainly of an ultraviolet curable acrylic resin,
0.7 parts of a system (polytetrafluoroethylene) powder was added, and 0.3 parts of PC (polycarbonate) beads having an average particle diameter of 20 μm were further added. Here, PT
The addition of the FE-based powder is for the purpose of improving the writing and erasing properties using a marker pigment, that is, a felt pen when used as an electrostatic sheet of an electronic blackboard.

Comparative Example 1 The hard coat layer 36 of Example 1 had a composition not containing only PC beads.

FIGS. 2 and 4 show the results of measuring the surface roughness of each of the electrostatic recording media of Example 1 and Comparative Example 1 using a surface roughness meter.
Shown in Further, FIGS. 3 and 5 show images when an electrostatic latent image is formed on the electrostatic recording medium according to Example 1 and Comparative Example 1 and a visible image appears with toner. As described above, the density is remarkably different from each other.
However, in Comparative Example 1, the concentration was about 0.5, and in the case of the present invention, the concentration was increased about twice. As mentioned above,
According to the configuration of the present invention, the surface can be roughened by adding the dielectric beads 37 to the hard coat layer 36 so that a visible image having a high density without a hollow and hence a high contrast can be produced. However, the dielectric beads have a relative dielectric constant of 5 or more, preferably 9 or more,
Further, when the particle size is 5 to 30 μm, 5 to 20 μm
Projection, that is, the maximum roughness is obtained, and in this range, the electrostatic latent image without hollowing over the entire area of the contact portion of the recording electrode. It was confirmed that a high image could be obtained. This is presumably because an optimum discharge gap is obtained between the recording electrode, that is, the stylus electrode 5 and the recording medium 1 in this roughness range.

In the above-described example, PC beads are used as the plastic beads constituting the dielectric beads 37. In addition, polyester beads, cellulose acetate resins, vinyl chloride resins, acrylic resins, styrene resins and the like are used. Because it is used as a white sheet in an electronic blackboard, transparent or white beads such as white transparent can be used.

[0034]

As described above, according to the structure of the present invention,
By applying a hard coat layer 36 to which dielectric beads 37 are added to the electrostatic recording medium, moderate irregularities are formed on the surface to generate a good discharge not only at the edge of the recording electrode but also at the center, As a result, electric charges are accumulated, so that it is possible to prevent the occurrence of voids in the recording dots of the visible image and improve the density. Therefore, a clear and excellent image can be displayed, and the practical benefit when used as an electronic blackboard is extremely large.

[Brief description of the drawings]

FIG. 1 is an enlarged schematic sectional view of an example of an electrostatic recording medium according to the present invention.

FIG. 2 is a diagram showing a measurement result of a surface roughness of an example of the electrostatic recording medium according to the present invention.

FIG. 3 is a schematic view of a visible image formed on an electrostatic recording medium according to the present invention.

FIG. 4 is a diagram showing a measurement result of a surface roughness of an electrostatic recording medium of a comparative example.

FIG. 5 is a schematic diagram of a visible image of an electrostatic recording medium of a comparative example.

FIG. 6 is a configuration diagram of an electronic blackboard using the electrostatic recording medium according to the present invention.

FIG. 7 is a sectional view of a conventional electrostatic recording medium.

FIG. 8 is a sectional view of a conventional electrostatic recording medium.

FIG. 9 is a perspective view of an electronic blackboard.

FIG. 10 is a front view of a recording head.

FIG. 11 is a configuration diagram of an electrostatic recording head.

FIG. 12 is an enlarged view of a recording dot.

FIG. 13 is a sectional view of a contact portion between a stylus electrode and an electrostatic recording medium.

[Explanation of symbols]

 21 Base 22 Adhesive 23 Conductive layer 24 Adhesive 25 Dielectric layer 36 Hard coat layer 37 Dielectric beads

Claims (1)

(57) [Claims] 1. An electrostatic recording medium comprising a sheet-like base, a conductive layer formed on the base, and a dielectric layer formed on the conductive layer, wherein dielectric beads are dispersed on the dielectric layer. An electrostatic recording medium characterized by being coated with a hard coat layer having a surface roughness of 5 to 30 μm.