JP2542724B2 - Sheet electrostatic adsorption method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to electrostatic attraction for holding a manuscript in an overhead projector or the like, or various documents or posters for posting on a transparent or opaque carrier. The present invention relates to a method for electrostatically attracting a sheet using a plate.

(Prior Art) In recent years, high-definition word processors and personal computers have advanced, and the print output has become finer, the sheet-shaped recording medium has become thinner and thinner.
Color recording is becoming popular.

However, such a high-definition recorded thin medium cannot hold a flat shape by itself, and for example, when it is placed on the original plate of an overhead projector, fine wrinkles cause more distortion of the projected image. There is a problem. 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.

On the other hand, in addition to the above general problems, the OH that has a very high resistivity of the substance to be adsorbed, for example, a resistivity of 10 ¹⁶ Ωcm or more.
Polyester films for P and the like cannot be firmly adsorbed and held by conventional electrostatic adsorption plates. Such a tendency becomes a particularly serious problem when electrostatically holding a polyester film or the like having a considerably large thickness vertically. The inventor conducted the following test in order to understand the relationship between the type of the object to be attracted and the magnitude of the electrostatic attraction force.

That is, a pair of comb-teeth-shaped electrodes formed between the insulating layer and the adsorption layer having a volume resistivity of about 10 ¹¹ Ωcm or more are formed in such a state that the comb-teeth-shaped electrodes are inserted into each other without contacting each other. The surface of the adsorption layer of the plate is brought into contact with the surface of the A4 size object to be adsorbed, and a direct current voltage of 2600 V (volt) is applied to the electrode to adsorb the object to be adsorbed on the adsorption plate. The force required for forcibly peeling off the adsorbent (adsorption force) and the current consumption (μA) in this state (simply referred to as current in the table below) were measured, and the results shown in Table 1 below were obtained. .

In Table 1, "conductive film" is a polyester film with indium tetrachloride vapor-deposited, "insulating film" is a raw polyester film with a thickness of 300 µm, "aluminum plate" has a thickness of 1 mm, and "copper plate" Thickness is 35μ
m.

As is clear from Table 1, the electrostatic adsorption action is extremely weak for an insulating film such as an OHP film, and it is almost impossible to adsorb. To solve this problem by the conventional method, an extremely thin transparent suction plate of, for example, about 25 to 50 μm is used, or an ordinary suction plate is extremely high.
For example, it is necessary to take measures such as applying a voltage of up to about 10,000 volts. However, the ultra-thin suction plate lowers the durability and is dangerous when a high voltage is used, which causes other problems.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide a sheet electrostatic adsorption method which does not have the above-mentioned drawbacks. An object of the present invention is to provide an effective and easy-to-implement sheet adsorption method for an object to be adsorbed, which is difficult to adsorb, by utilizing the strength of the electrostatic adsorption action on the electrically conductive sheet-like material as shown in the table.

(Means for Solving the Problem) In order to achieve this object, the sheet electrostatic adsorption method according to the present invention comprises an insulating layer and an adsorption layer composed of a dielectric material having a volume resistivity of about 10 ¹¹ Ωcm or more. A pair of comb-teeth-shaped electrodes are formed in such a manner that the comb-teeth portions are inserted without coming into contact with each other, and one surface of the object to be adsorbed is brought into contact with the surface of the adsorption layer of the adsorption plate. Then, in the sheet electrostatic adsorption method for adsorbing the adsorbate to the adsorbing plate by applying a DC voltage to the electrode to impart an electrostatic charge to the surface of the adsorbing layer, the other side of the adsorbent is The surface has a resistivity of about 10 ⁸ Ωc
A pressing sheet having a conductivity of m or less is brought into contact with the surface of the adsorption layer, and a portion of the pressing sheet facing the electrostatic charge causes a static charge having a polarity opposite to that of the static charge to be dielectrically generated. To do.

In the present invention, the distance between both electrodes of the suction plate, that is, the distance between the adjacent comb-teeth-shaped portions is in the unit of mm, for example, about 2 mm, but the distance between these electrodes and the conductive surface layer of the holding sheet is in the unit of μm, for example, at most. It is an important condition that the thickness is about 500 μm.

(Operation) In the sheet electrostatic adsorption method of the present invention, due to the distance relationship as described above, in the adsorption layer from one positive electrode side electrode comb tooth portion P to the adjacent negative electrode side electrode comb tooth portion N or Compared to the linear electric field strength in the insulating layer (see FIG. 1), the conductive surface layer C leads to the portion C1 of the conductive surface layer C facing the portion from the comb tooth portion P and proceeds in the surface layer C. Thus, the arc-shaped electric field strength returning from the portion C2 facing the comb tooth portion N to the comb tooth portion N becomes much stronger.

Therefore, it is considered that a strong electrostatic charge due to polarization is generated in the part of the object to be adsorbed at the position on the arc-shaped electric field line which is in contact with the parts C1 and C2, and the adsorption force becomes large.

(Effects of the Invention) According to the present invention, as described above, the pressing sheet having the electrically conductive surface layer is used as the pressing sheet for sandwiching the object to be adsorbed between the adsorption plate and the conventional structure. Was able to reliably adsorb completely insulating polyester films (eg OHP films) and thick posters that were difficult or insufficient to adsorb.

(Example) Next, a specific example of the sheet adsorption method according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, in this embodiment, an insulating layer (22) and an adsorption layer (26) are a pair of positive and negative electrodes (24a) (24b) (on a flat substrate (10). In the figure, the suction plate (20) with sandwiching the comb teeth is placed, and the power supply (1
From 2), a device was constructed so that a DC voltage of 2600V could be applied to the electrode via a connector (14). The resistivity of the adsorption layer (26) was about 10 ¹³ Ωcm. An insulating polyester film for OHP, for example, is used as the object to be adsorbed (40), and the object to be adsorbed (40) is held by the holding sheet (50) to the adsorption plate (2).
It was pinched between 0). The conductive surface layer (50a) formed on the surface of the presser sheet (50) is 10 ⁸ Ωcm or less, for example, about 10
^It has a resistivity of about ³ Ωcm and indium tetrachloride is previously vapor-deposited on the surface of the base film. In this case, since strong electrostatic charges having opposite polarities are generated at the opposing portions of the adsorption layer (26) and the pressing sheet (50) to attract each other, the object to be adsorbed (40) sandwiched between the two is highly advanced. Even though it is insulating, it is held by the suction plate (20). Applied voltage
When the object to be adsorbed (40) was adsorbed at 2600 V and the force required for peeling was measured by pulling in the direction of the arrow (W) in the figure with a spring balance, the adsorbing force was about 3 Kg or more. For comparison, when a presser sheet having a resistivity of about 10 ¹⁶ Ωcm was used, the force required for peeling off was insufficient at about 1 kg.

The above measurement results show that, due to the conductive surface layer (C), the comb-teeth part reaches from the (P, 24a) to the part (C1) of the conductive surface layer (C, 50a) facing the part and the surface layer (C ), The arc-shaped electric field strength returning from the part (C2) facing the comb tooth part (N, 24b) to the comb tooth part (N) becomes much stronger than the electric field strength in the other direction, and these parts This suggests that a strong electrostatic charge is generated at (C1, C2). And in the comparative example in which the conductive surface layer (50a) is not provided on the adsorbed material and the comparative example in which the surface of the adsorption layer (26) is electrically conductive, the electric field lines hardly pass through the adsorbed material. Therefore, it is considered that the fact that no electrostatic charge is generated in the substance to be adsorbed causes a weak adsorption force.

The sheet adsorption method of this embodiment can be used not only for adsorption of OHP films but also for various purposes. For example, a transparent suction plate (20) is attached to the glass of a show window (corresponding to the substrate in this embodiment), and a label or a display medium is cut between the plate surface and the transparent conductive holding sheet (50). It is convenient because a character or a pattern is sandwiched and a DC voltage is applied to the adsorption plate so that the sign or the like can be easily attached and detached and the design change can be dealt with more easily than before.
It should be noted that as the power supply, since the current consumption is about several microamperes, AA to AA dry batteries may be used, but 2000 to 30
Need a transformer to boost to 00V.

When used as a poster board indoors or outdoors, the suction plate (20) may be opaque, but the holding sheet (50).
Will be transparent. In the case of an electric poster board, a transparent light diffusing plate that diffuses light rays from a light source is used as a substrate on the back of the transparent suction plate (20), and a transparent light diffusion plate is provided between the transparent holding plate (50) and the transparent holding sheet (50). A poster or the like may be held by electrostatic attraction. Furthermore, grit type XY
When a reinforcement sheet (using residual suction force) is used in a plotter, if the object to be attracted is covered with a conductive pressing sheet (50) and electrostatically adsorbed, the residual suction force after removing the pressing sheet can be increased. It is convenient.

Regarding the method of the present invention described above, the position of the conductive surface layer is opposite to the illustrated example, that is, it is arranged on the surface of the holding sheet (50) which is separated from the suction plate (20), and the like. Can be added.

[Brief description of drawings]

 FIG. 1 is a schematic sectional view showing an embodiment of the present invention. (10) ... Substrate, (20) ... Suction plate, (22) ... Insulation layer, (24a) (24b) ... Electrode, (26) ... Suction layer, (40) ... Adsorption target, (50a) …… Conductive surface layer, (50) …… Presser sheet,

Claims (1)

(57) [Claims] 1. A pair of comb-teeth-shaped electrodes are inserted between an insulating layer and an adsorption layer made of a dielectric material having a volume resistivity of about 10 ¹¹ Ωcm or more without contacting the comb-teeth portions with each other. The surface of one side of the object to be adsorbed is brought into contact with the surface of the adsorbing layer of the adsorbing plate formed in a state of being placed, and a DC voltage is applied to the electrode so that an electrostatic charge is applied to the surface of the adsorbing layer. In the sheet electrostatic adsorption method of adsorbing the adsorbate to the adsorption plate by doing, on the surface of the other side of the adsorbent, the resistivity is about 10 ⁸ Ωcm
It is characterized in that a pressing sheet having the following conductivity is brought into contact with the surface of the adsorption layer, and a static charge having a polarity opposite to that of the static charge is dielectrically generated at a portion of the pressing sheet facing the static charge. Sheet electrostatic adsorption method.