JPH0744859B2 - Transparent electrostatic adsorption sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used as, for example, a document placing plate in an overhead projector, a transparent plate for displaying or displaying various documents and posters, or the like, or Relates to a transparent electrostatic adsorption sheet to be used as those members.

(Prior Art) In recent years, as word processors and personal computers have become more sophisticated, and the print output thereof has become finer, the sheet-shaped recording medium has become thinner and thinner, and color recording has become widespread.

However, such a thin medium on which high-definition recording is performed is not able to maintain a flat shape by itself due to partial warpage due to partial adhesion of printing toner, and for example, in an overhead projector. There is a problem that the projection image is distorted due to fine wrinkles when placed on the original plate. This distortion is particularly unsightly for high-definition characters and the like. Such a problem is also a problem when, for example, the print record or handwritten document is posted on a transparent glass such as a show window.

However, an effective and practical support for holding an extremely thin sheet or film recording medium or a display medium in a flat position without wrinkles or waviness has not yet been provided to consumers. The current situation.

(Problems to be Solved by the Invention) Accordingly, an object of the present invention is to provide a transparent electrostatic adsorption sheet having a strong adsorption force as a support for a recording medium or the like without the above-mentioned drawbacks.

(Means for Solving the Problem) In order to achieve the above-mentioned object, the transparent electrostatic adsorption sheet of the present invention has a pair of transparent comb-teeth-shaped electrodes on the back surface of a transparent insulating synthetic resin film. Areas of the back surface of the synthetic resin film and the comb-teeth-shaped electrodes which are formed in such a manner that the comb-teeth portions are not in contact with each other and are not covered by the comb-teeth-shaped electrodes, It is characterized by being covered with a bonded transparent insulating adhesive layer.

In one aspect of the present invention, a self-shape-retaining transparent substrate is attached to the back surface of the transparent insulating adhesive layer. This transparent substrate can be selected from synthetic resin film, synthetic resin sheet, glass and Fresnel lens.
Furthermore, the volume resistivity of each of the insulating synthetic resin film and the transparent insulating adhesive layer is about 10 ¹² Ωcm or more,
It is desirable that the comb-tooth-shaped electrode has a volume resistivity of about 10 ⁵ Ωcm or less, and the visible light transmittance of each of the insulating synthetic resin film, the transparent insulating adhesive layer and the transparent substrate is about 70% or more. . This visible light transmittance is about 80%
It is more desirable that the above is satisfied.

The insulating synthetic resin film is formed of, for example, polyester, polycarbonate, acrylic resin or the like, and its thickness is preferably in the range of about 100 to 500 μm. From the viewpoint of visible light transmittance, it is better to be thin, but from the viewpoint of planar shape retention, it is better to be thick, while from the viewpoint of suitable volume resistivity (Ωcm), for example, a thickness of 50 to 150 μm In case 10 ¹⁵ Ωcm
And a relatively low resistivity of 10 ¹² to 10 ¹⁴ Ωcm in the case of a thickness of 200 to 500 μm is desirable in order to give good chargeability (quantity) and to keep the adsorption force high. .

The transparent comb-shaped electrode is an extremely thin metal layer having a thickness of 0.1 to 20 μm, which is formed on the entire surface of one side of the synthetic resin film by, for example, indium trioxide (ITO) sputtering, ion plating or surface crystallization. After the metal thin film is formed, etching can be performed in a shape in which the comb-shaped portion is left. Alternatively, the metal thin film may be formed by masking the area other than the comb teeth without forming the metal thin film on the entire surface.

The metal thin film can be formed by vacuum deposition of gold, silver, copper, aluminum or the like instead of indium trioxide, but in that case, the thickness is preferably about 0.01 to 1.0 μm from the viewpoint of transparency, and originally has high conductivity. Since it is the above-mentioned metal, a resistivity of 10 ⁵ Ωcm or less can be obtained as in the case of indium trioxide.

As the adhesive for the transparent insulating adhesive layer, a copolymer of alkyl acrylate, a two-pack type epoxy polymer, or an ultraviolet curable type can be used. These are 10 ¹² Ω
It is desirable to have a resistivity of not less than cm, particularly 10 ¹³ to 10 ¹⁶ Ωcm, that is, an insulating property. The thickness of the adhesive layer is made as thin as possible from the viewpoint of visible light transmittance, and for example, 30 to 100 μm is sufficient.

In the present invention, a transparent electrostatic adsorption sheet may be used in a state where release paper is temporarily attached to the surface of the adhesive layer.
A transparent substrate may be attached to the surface of the adhesive layer. For the transparent substrate (synthetic resin sheet, Fresnel lens, etc.) in that case, an optimum thickness is selected in consideration of the visible light transmittance and the self-shape retention. However, in general
A thickness of about 100 to 300 μm is suitable.

An additional adhesive layer may be provided on the surface of the transparent substrate (the lower surface in the drawings described later). Alternatively, a transparent synthetic resin film or sheet may be directly laminated (for example, welded) instead of the adhesive layer covering the electrodes.

(Operation) Between the pair of comb-shaped electrodes sandwiched between the transparent insulating synthetic resin film of the present invention and the transparent insulating film having the above-mentioned structure, for example, a DC voltage of about 1,000 to 3,000 V is applied. When applied, the film and the coating both have an electrostatic charge due to the strong electric field due to this, and if a thin original, for example, an OHP original (automatic printing or handwriting) is placed on the surface of the film, It strongly adheres to the film and its flatness is not lost by vibration, tilt, wind, etc. Even if the document surface has minute wrinkles as described above, it is forcibly stretched when it is adsorbed.

Therefore, due to the transparency of the film and coating, a normal and beautiful image can be obtained not only by visual observation (through glass, etc.) but also by OHP. Moreover, because of its transparency, it can be viewed or projected from both front and back sides, which is convenient for graphics.

To remove the original from the transparent synthetic resin film surface, the DC power supply should be turned off.However, if it takes a long time for the static charge to disappear, the polarity of the applied voltage can be instantaneously reversed to immediately remove the original. It can be removed. This is convenient for continuously and quickly switching documents in OHP or the like.

(Effects of the Invention) As described above, the present invention provides a transparent electrostatic attraction sheet having a strong suction force, and particularly various layer constructions on the side opposite to the original attraction surface (back side) are provided. Since it can take various forms, it can be used in a wide variety of applications such as OHP, glass surface (show window) attachment, and attachment or attachment to a blackboard.

(Example) Hereinafter, one example will be described with reference to the drawings.

In the adsorption sheet (T) of the embodiment shown in FIG. 1, a transparent insulating synthetic resin film having a thickness of 300 μm was formed on the lower surface (above the drawing) of the polyester film (1) by a sputtering method, and then isodium trioxide was used. A thin film (ITO) transparent electrode (2) is formed. This is one in which ITO was once attached to the entire surface of the film and then etched into a comb shape as shown in FIG. The thickness of the transparent and comb-shaped electrode was about 10 μm, and the volume resistivity of the polyester film (1) was about 10 ¹³ Ωcm.

The transparent insulating adhesive layer (3) is an acrylic ester copolymer, its thickness is about 50 μm, and its volume resistivity is about 10 ¹⁴ Ωcm.
Is.

To cover the transparent insulating adhesive layer (3), a polyester film (4) as a transparent substrate with a thickness of about 150 μm is attached to the lower surface, and in this state, onto the OHP projection table (5) in FIG. It is suitable for being placed. Place the original (G) on this suction sheet (T), and direct current power supply (P)
If (Fig. 3) is inserted, the document is strongly attracted to the suction sheet without wrinkles. When the light source (K) is turned on, the characters (M) on the document are reflected by the mirror (6) and the screen (7)
It was confirmed that it was a beautiful image with no distortion, though it was formed on top.

In the embodiment shown in FIG. 2, instead of the polyester film (4) as the transparent substrate of the previous example, a Fresnel lens (4 ') is attached to the lower surface of the adhesive layer (3). In other respects, it is the same as the example of FIG. 1, but in this case, this suction sheet (T ') itself can be used as the original placing plate of the OHP projector. Reference numeral (L) indicates a light ray from the light source.

In any of the above structures, the transparent insulating synthetic resin film (1), the transparent insulating adhesive layer (3) and the transparent substrates (4) and (4 ') have a visible light transmittance of about 80% or more.

[Brief description of drawings]

FIG. 1 shows the present invention, FIG. 1 is a sectional view of a suction sheet of the first embodiment, FIG. 2 is a sectional view of a suction sheet of the second embodiment, and FIG. 3 is a plan view of suction sheets in both embodiments. The figure is a perspective view of the suction sheet of the first embodiment in use. (1) …… Transparent insulating synthetic resin film (2) …… Transparent electrode (3) …… Transparent insulating adhesive layer (4) (4 ′) …… Transparent substrate (5) …… OHP projection table ( 6) …… Mirror (P) …… DC power supply

Claims (6)

[Claims] 1. A back surface of a transparent insulating synthetic resin film,
A pair of transparent comb-teeth-shaped electrodes are formed in such a manner that the comb-teeth portions are inserted without contacting each other, and the area on the back surface of the synthetic resin film not covered by the comb-teeth-shaped electrodes and the comb-teeth A transparent electrostatic adsorption sheet, characterized in that the electrodes are covered with a transparent insulating adhesive layer bonded to these regions and the comb-shaped electrodes. 2. The volume resistivity of each of the insulating synthetic resin film and the transparent insulating adhesive layer is about 10 ¹² Ωcm or more, and the volume resistivity of the comb-shaped electrode is about 10 ⁵ Ωcm or less, The transparent electrostatic adsorption sheet according to claim 1, wherein the visible light transmittance of each of the insulating synthetic resin film and the transparent insulating adhesive layer is about 70% or more. 3. The transparent electrostatic adsorption sheet according to claim 1, wherein a transparent substrate having a self-shape retaining property is attached to the back surface of the transparent insulating adhesive layer. 4. The transparent electrostatic attraction sheet according to claim 3, wherein the transparent substrate is selected from a synthetic resin film, a synthetic resin sheet, glass and a Fresnel lens. 5. The volume resistivity of each of the insulating synthetic resin film and the transparent insulating adhesive layer is about 10 ¹² Ωcm or more, and the volume resistivity of the comb tooth-shaped electrode is about 10 ⁵ Ωcm or less, The insulating synthetic resin film, the synthetic insulating adhesive layer and the transparent substrate each have a visible light transmittance of about 70.
% Or more, the transparent electrostatic adsorption sheet according to claim 3 or 4. 6. The transparent electrostatic attraction sheet according to claim 3, further comprising another adhesive layer provided on the back surface of the transparent substrate.