Workpiece suction device

Abstract

Provided is a workpiece attraction device that can, even when conveying a thin workpiece such as paper, cloth, or a resin film, reliably dechuck (separate) an attracted workpiece in a short period of time.　This workpiece attraction device comprises: an electrostatic attracting body (1) which is capable of attracting a workpiece (W) onto a workpiece attracting surface (1a) by applying voltage to attraction electrodes (4a, 4b); and a workpiece separator (5) which is to be interposed between the attracted workpiece and the electrostatic attracting body and which assists in separating the workpiece from the workpiece attracting surface after the voltage application to the attraction electrodes is stopped. The workpiece separator has formed therein multiple openings (6) that are for causing a workpiece attracting force generated in the workpiece attracting surface to act on the workpiece side, and is also partitioned by a grid part (7) so as to have the respective openings arranged in a substantially uniform configuration in the surface of the workpiece separator. The attraction electrodes of the electrostatic attracting body and the grid part of the workpiece separator do not face opposite each other in a plan view from the workpiece side when the workpiece is attracted.

Description

Technical Field

[0001] This invention relates to a work adsorption device including an electrostatic adsorber that adsorbs a work on a work adsorption surface and a work separator that assists in separating the work from the work adsorption surface after the work is adsorbed. More specifically, it relates to a work adsorption device that can separate the work from the work adsorption surface in a short time and reliably when de-chucking the work from the work adsorption surface.

Background Art

[0002] When a voltage is applied to an electrostatic adsorber having an adsorption electrode inside to adsorb a work, and then when separating the work from the work adsorption surface, there may sometimes occur a phenomenon that the work cannot be successfully separated (de-chucked) due to residual charges. These occur depending on the type of work, and are particularly prominent in soft and thin works such as paper, cloth, and resin films.

[0003] Regarding such de-chucking failures, for example, in the case of attaching an electrostatic adsorber to the robot hand side to convey the work, conveyance failures such as positional deviation when separating the work at the conveyance destination or carrying the work back as it is may occur. Also, although it is conceivable to prevent positional deviation of the work by waiting until the influence of the residual charge decreases after stopping the voltage application, the cycle time from adsorption to separation of the work becomes long.

[0004] Therefore, a method of applying a reverse voltage during de-chucking of the work is known (see, for example, Patent Document 1). That is, a reverse voltage having a polarity opposite to that during electrostatic adsorption for adsorbing the work to the electrostatic adsorber is applied to reduce the residual charge, so that the separation of the work can be performed smoothly.

[0005] However, this method is easily affected by the work, and the reverse voltage to be applied changes depending on the material, physical properties, surface state of the work to be conveyed, or the surrounding environment. Therefore, it is difficult to actually eliminate the above-described conveyance failures and the like.

[0006] Another example involves using a charged plate that has been charged by friction with a charging brush. In this method, a shutter that can be opened and closed is provided between the charged plate and an attachment plate to which the workpiece is attached on the underside. When separating (dropping) the workpiece attached to the underside of the attachment plate, the shutter is closed to block the adhesive force of the charged plate (see Patent Document 2).

[0007] Furthermore, in a transport device that transports a workpiece by adsorbing it onto an electrostatic adsorption plate having an electrode inside, a release plate having an opening is provided between the electrostatic adsorption plate and the workpiece. This allows the release plate to adhere closely to the electrostatic adsorption plate when the workpiece is adsorbed, and to separate from the electrostatic adsorption plate when the workpiece is released (separated), thereby reducing the electrostatic adsorption force (workpiece adsorption force) exerted by the electrostatic adsorption plate on the workpiece (see Patent Document 3).

[0008] These methods employ direct means to block or eliminate the suction force on the workpiece during dechucking. Therefore, although some effectiveness is observed, with repeated use, the workpiece adheres to the adhesion plate (Patent Document 2) or release plate (Patent Document 3), which still hinders the separation of the workpiece. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 11-330217 [Patent Document 2] Japanese Patent Application Publication No. 58-207230 [Patent Document 3] Japanese Patent Publication No. 2007-45618 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] As illustrated above, in various transport operations such as picking up workpieces by attaching an electrostatic adsorbent to a robot hand or moving workpieces between locations, if the dechuck (separation) of the workpiece cannot be performed accurately and quickly, the cycle time from adsorption to separation of the workpiece will increase, reducing productivity. However, when transporting thin workpieces such as paper, cloth, or resin film, it is particularly difficult to eliminate the transport problems described above because they are susceptible to residual charge.

[0011] Therefore, the inventors diligently studied methods to prevent the effects of residual charge, and as a result, they discovered that in a workpiece adsorption device that interposes a workpiece separator between an electrostatic adsorbent having internal adsorption electrodes to adsorb a workpiece and the workpiece, and that assists in separating the workpiece from the electrostatic adsorbent after the workpiece has been adsorbed, the above-mentioned problems can be solved by preventing dielectric polarization or electrostatic induction of the workpiece separator when the workpiece is adsorbed, and thus completed the present invention.

[0012] Therefore, the object of the present invention is to provide a workpiece suction device that can quickly and reliably dechuck (separate) a suctioned workpiece, even when transporting thin workpieces such as paper, cloth, or resin film. [Means for solving the problem]

[0013] In other words, the gist of the present invention is as follows: (1) A workpiece adsorption device comprising: an electrostatic adsorbent having an internal adsorption electrode that generates a workpiece adsorption force when a voltage is applied to it, thereby adsorbing a workpiece onto the workpiece adsorption surface; and a workpiece separator interposed between the adsorbed workpiece and the electrostatic adsorbent to assist in separating the workpiece from the workpiece adsorption surface after the application of voltage to the adsorption electrode is stopped, The workpiece separator has a plurality of openings for applying the workpiece suction force generated on the workpiece suction surface to the workpiece, and the openings are partitioned by a grid so that they are substantially uniformly located within the plane of the workpiece separator, and the workpiece suction device is characterized in that, when viewed from the workpiece side in plan view during workpiece suction, the suction electrodes of the electrostatic suction body and the grid of the workpiece separator do not face each other. (2) The workpiece adsorption apparatus according to (1), wherein the grid portion of the workpiece separator is arranged to surround the adsorption electrode of the electrostatic adsorbent, and when viewed from the workpiece side in plan view during workpiece adsorption, the adsorption electrode of the electrostatic adsorbent and the grid portion of the workpiece separator do not face each other. (3) A workpiece adsorption device comprising an electrostatic adsorbent having an internal adsorption electrode and capable of adsorbing a workpiece to a workpiece adsorption surface by applying a voltage to it, and a workpiece separator interposed between the adsorbed workpiece and the electrostatic adsorbent to assist in separating the workpiece from the workpiece adsorption surface after the application of voltage to the adsorption electrode is stopped, A workpiece adsorption device characterized in that the workpiece separator has a plurality of openings for applying the workpiece adsorption force generated on the workpiece adsorption surface to the workpiece, and the openings are partitioned by a grid so that they are substantially uniformly located within the surface of the workpiece separator, and a conductive shielding member is interposed between the grid of the workpiece separator and the adsorption electrode of the electrostatic adsorbent. (4) The workpiece adsorption device according to (3), wherein the conductive shielding member is disposed on the electrostatic adsorbent. (5) A workpiece adsorption device comprising an electrostatic adsorbent having an internal adsorption electrode and capable of adsorbing a workpiece to a workpiece adsorption surface by applying a voltage to it, and a workpiece separator interposed between the adsorbed workpiece and the electrostatic adsorbent to assist in separating the workpiece from the workpiece adsorption surface after the application of voltage to the adsorption electrode is stopped, The workpiece separator has a plurality of openings for applying the workpiece adsorption force generated on the workpiece adsorption surface to the workpiece side, and is partitioned by a lattice portion so that the openings are substantially uniformly present in the plane of the workpiece separator. When viewed from the workpiece side during workpiece adsorption, the adsorption electrode of the electrostatic adsorber and the lattice portion of the workpiece separator do not face each other, and a conductive shielding member is interposed between the lattice portion of the workpiece separator and the adsorption electrode of the electrostatic adsorber. A workpiece adsorption device characterized by this. (6) The workpiece adsorption device according to any one of (3) to (5), wherein the conductive shielding member is connected to the ground. [Effect of the Invention]

[0014] According to the workpiece adsorption device of the present invention, even when transporting a thin workpiece such as paper, cloth, resin film, etc., the adsorbed workpiece can be de-chucked (separated) in a short time and reliably. In particular, in the present invention, when adsorbing a workpiece, the workpiece separator is not dielectrically polarized or electrostatically induced, so it is less affected by the type and shape of the workpiece or the surrounding environment such as humidity, and a general-purpose workpiece adsorption device can be realized. [Brief Description of the Drawings]

[0015] [Figure 1] FIG. 1 is a diagram for explaining an example of the workpiece adsorption device in the present invention, (a) represents a plan view, and (b) represents a cross-sectional view taken along X-X' in (a). [Figure 2] FIG. 2 is a diagram for explaining another example of the workpiece adsorption device in the present invention, (a) represents a plan view, and (b) represents a cross-sectional view taken along X-X' in (a). [Figure 3] FIG. 3 is a diagram for explaining another example of the workpiece adsorption device in the present invention, (a) represents a plan view, and (b) represents a cross-sectional view taken along X-X' in (a). [Figure 4] FIG. 4 is a diagram for explaining another example of the workpiece adsorption device in the present invention, (a) represents a plan view, and (b) represents a cross-sectional view taken along X-X' in (a). [Figure 5] Figs. 5(a) and 5(b) are plan views for showing an example of a lattice portion of a work separator. [Figure 6] Figs. 6(a) and 6(b) are cross-sectional views for explaining the operation of a work separator in a work suction device. [Figure 7] Fig. 7 is a cross-sectional view showing an example of the installation state of a work separator in a work suction device. [Figure 8] Fig. 8 is a plan view showing an example of a suction electrode in an electrostatic suction body of a work suction device. [Figure 9] Fig. 9 is a view for explaining the test electrostatic suction body used in Example 1. (a) is a plan view for explaining a suction electrode 24 composed of comb-shaped electrodes 24a and 24b, and (b) represents a cross-sectional view taken along X-X' in (a). [Figure 10] Fig. 10 shows the result of measuring the surface potential of the test electrostatic suction body of Example 1. [Figure 11] Fig. 11 shows the result of measuring the surface potential of the test electrostatic suction body of Example 2.

Embodiments for Carrying out the Invention

[0016] Hereinafter, the present invention will be described in detail. The present invention relates to an electrostatic suction body that has a suction electrode inside and can generate a work suction force by applying a voltage to adsorb a work on a work suction surface, and a work separator that is interposed between the adsorbed work and the electrostatic suction body and assists in separating the work from the work suction surface after the application of the voltage to the suction electrode is stopped. In a work suction device provided with the above, when applying a voltage to the suction electrode to adsorb the work, the work separator is not dielectrically polarized or electrostatically induced, so as to minimize the influence of residual charges after the application of the voltage to the suction electrode is stopped.

[0017] More specifically, the work separator has multiple openings for applying the work suction force generated on the work surface to the workpiece, and these openings are partitioned by a grid so that they are substantially uniformly located within the plane of the work separator, so that when a voltage is applied to the adsorption electrode, the grid of the work separator does not undergo dielectric polarization or electrostatic induction. In order to prevent dielectric polarization or electrostatic induction of the grid of the work separator, the present invention can specifically show the following embodiments. Note that the method of dielectric polarization or electrostatic induction is used depending on the material that constitutes the grid of the work separator, but in short, the present invention aims to prevent charge unevenness in the grid of the work separator and to prevent charge generation on the surface of the grid when a voltage is applied to the adsorption electrode to adsorb a workpiece, thereby minimizing residual charge as much as possible.

[0018] First, as the first embodiment, this is a workpiece adsorption device in which, when viewed from the workpiece side in a plan view during workpiece adsorption, the adsorption electrodes of the electrostatic adsorbent and the grid portion of the workpiece separator do not face each other.

[0019] Here, "viewing from the workpiece side in plan view during workpiece adsorption" refers to the state in which the workpiece is adsorbed onto the electrostatic adsorbent, that is, when a workpiece adsorption force acts between the workpiece and the electrostatic adsorbent, causing the workpiece to be adsorbed onto the electrostatic adsorbent, and a workpiece separator is tightly interposed between the workpiece and the electrostatic adsorbent, and this view is viewed from the workpiece side in plan view, representing the relative positional relationship between the adsorption electrodes of the electrostatic adsorbent and the grid portion of the workpiece separator at that time. In other words, when the adsorption electrodes of the electrostatic adsorbent and the grid portion of the workpiece separator are projected onto the workpiece adsorption surface, they are positioned so that they do not overlap each other. Specifically, an example of such a workpiece adsorption device is one in which the grid portion of the workpiece separator is arranged to surround the adsorption electrodes of the electrostatic adsorbent.

[0020] Figure 1 shows a specific example. In this example, the electrostatic adsorbent 1 is equipped with a bipolar adsorption electrode 4 consisting of an adsorption electrode 4a to which a positive voltage is applied and an adsorption electrode 4b to which a negative voltage is applied. The workpiece separator 5 has multiple openings 6 for applying the workpiece adsorption force generated on the workpiece adsorption surface 1a of the electrostatic adsorbent 1 to the workpiece w, and these openings 6 are partitioned by a grid portion 7 so that they are distributed substantially uniformly within the plane of the workpiece separator 5.

[0021] In Figure 1, the grid section 7 is formed by a frame 7a and a plurality of connecting sections 7b that connect the frame 7a in the vertical direction. Of these, the connecting sections 7b are aligned along the length of the adsorption electrodes 4a and 4b, and when viewed from the workpiece w side during workpiece adsorption, the connecting sections 7b are located in positions corresponding to the gaps between adjacent adsorption electrodes 4a and 4b. The frame 7a is located outside the entire adsorption electrode 4, which consists of the adsorption electrodes 4a and 4b.

[0022] As a result, the grid portion 7 of the work separator 5 is arranged to surround the adsorption electrode 4 of the electrostatic adsorbent 1, and the frame 7a and each connecting portion 7b do not overlap with the adsorption electrode 4 of the electrostatic adsorbent 1 in the thickness direction of the work adsorption device, and the adsorption electrode 4 of the electrostatic adsorbent 1 and the grid portion 7 of the work separator 5 do not face each other. Therefore, when a voltage is applied to the adsorption electrode, the grid portion 7 of the work separator 5 is not directly above the adsorption electrode 4 (4a, 4b), so the grid portion 7 of the work separator 5 is not subjected to dielectric polarization or electrostatic induction, and even if the workpiece w is repeatedly adsorbed and separated (desorbed), residual charge will not accumulate, thus preventing the workpiece w from adhering to the work separator 5.

[0023] Next, as a second embodiment, a workpiece adsorption device can be described in which a conductive shielding member is interposed between the grid portion of the workpiece separator and the adsorption electrode of the electrostatic adsorbent.

[0024] Figure 2 specifically shows an example of a second embodiment. In this example, the electrostatic adsorbent 1 is equipped with bipolar adsorption electrodes 4a and 4b, similar to the case in Figure 1. On the other hand, the workpiece separator 5 is equipped with an opening 6 and a grid section 7, similar to the case in Figure 1, but the connecting section 7b' that forms the grid section 7 is connected laterally within the frame 7a, and the connecting section 7b' crosses the adsorption electrodes 4a and 4b.

[0025] In this second embodiment, the connecting portion 7b' corresponds to the portion that crosses the adsorption electrodes 4a and 4b, and a conductive shielding member 8 is interposed between these connecting portion 7b' and the adsorption electrodes 4a and 4b. As a result, the grid portion 7 of the work separator 5 is not directly above the adsorption electrodes 4 (4a and 4b), so when a voltage is applied to the adsorption electrodes 4, the grid portion 7 of the work separator 5 is not subjected to dielectric polarization or electrostatic induction, and as in the first embodiment, it is possible to prevent the workpiece w from adhering to the work separator 5. Furthermore, it is preferable to provide this conductive shielding member 8 on the electrostatic adsorbent 1. In the plan view shown in Figure 2(a), even if residual charge is generated on the workpiece w at the boundary between the conductive shielding member 8 and the adsorption electrode 4a (or adsorption electrode 4b), when the workpiece separator 5 separates from the workpiece adsorption surface 1a of the electrostatic adsorbent 1 to dechuck the workpiece w, the conductive shielding member 8 remains on the electrostatic adsorbent 1 side, preventing the residual charge on the workpiece w from acting on the workpiece separator 5 and causing the workpiece to adhere. When providing the conductive shielding member 8 on the electrostatic adsorbent 1, it may be placed on the workpiece adsorption surface 1a of the electrostatic adsorbent 1, or it may be embedded inside the electrostatic adsorbent 1.

[0026] In this invention, the first and second embodiments described above can be specifically cited to prevent dielectric polarization or electrostatic induction of the lattice portion of the workpiece separator when a voltage is applied to the adsorption electrode, but these can be modified or combined as appropriate.

[0027] For example, Figure 3 shows a workpiece adsorption device according to a third embodiment, which combines the first and second embodiments. In this example, the connecting portion 7b that forms the grid portion 7 of the workpiece separator 5 is located at a position corresponding to the gap between adjacent adsorption electrodes 4a and 4b, and the frame 7a is located outside the entire adsorption electrode 4 consisting of each adsorption electrode 4a and 4b, and these do not overlap with the adsorption electrodes 4 of the electrostatic adsorbent 1 in the thickness direction of the workpiece adsorption device. In addition, since a conductive shielding member 8 is interposed between the connecting portion 7b' provided in a direction transverse to the adsorption electrodes 4a and 4b and the adsorption electrodes 4a and 4b, the grid portion 7 of the workpiece separator 5 does not undergo dielectric polarization or electrostatic induction when a voltage is applied to the adsorption electrodes 4.

[0028] Furthermore, Figure 4 shows a workpiece adsorption device of a fourth embodiment, which is a modified example of the first embodiment. In this example, multiple (four in Figure 4) electrostatic adsorbents 1, each having adsorption electrodes 4 (4a, 4b) inside, are arranged on a support material 9. The grid portion 7 of the workpiece separator 5 is formed by a frame 7a, a connecting portion 7b that connects the frame 7a vertically, and a connecting portion 7b' that connects the frame 7a horizontally. The grid portion 7 of the workpiece separator 5, formed by the frame 7a and the connecting portions 7b, 7b', is arranged to surround the adsorption electrodes 4 (4a, 4b) of each electrostatic adsorbent 1. The frame 7a and the connecting portions 7b, 7b' do not overlap with the adsorption electrodes 4 of each electrostatic adsorbent 1 in the thickness direction of the workpiece adsorption device, and the adsorption electrodes 4 of the electrostatic adsorbent 1 and the grid portion 7 of the workpiece separator 5 do not face each other.

[0029] As described above, the workpiece separator in the present invention has multiple openings for applying the workpiece suction force generated on the workpiece suction surface to the workpiece, and these openings are partitioned by a grid so that they are substantially uniformly distributed within the surface of the workpiece separator. In the example described above, the grid of the workpiece separator is formed by a frame and connecting parts that connect the inside of the frame in the vertical direction and connecting parts that connect in the horizontal direction, but for example, the grid can be formed by connecting parts that intersect in the vertical and horizontal directions without a frame. Furthermore, the angle at which the connecting parts intersect may be any angle other than 90 degrees, so that they intersect diagonally, and the grid of the workpiece separator can be appropriately designed and formed according to the shape of the suction electrodes in the electrostatic adsorbent, the size of the workpiece and the workpiece suction surface, etc. The same applies to the openings of the workpiece separator.

[0030] Furthermore, when forming the lattice section of the workpiece separator, various materials such as resin (plastic), metal, and wood can be used. There are no particular restrictions on the material, and these can be used in combination. Alternatively, a frame can be formed from a material with a certain degree of rigidity, such as resin or metal, and the connecting parts can be formed inside the frame using metal wires such as conductive wires, synthetic fibers such as nylon threads, wire materials such as ropes, threads, or yarns, as well as resin or tape. To give some specific examples, as shown in Figure 5(a), for example, a lattice section 7 can be formed by stretching nylon threads with a diameter of about 100 μm vertically and horizontally across an aluminum frame 7a to form connecting parts 7b, or as shown in Figure 5(b), a resin connecting part 7b with an opening 6 provided in a PET film with a thickness of about 50 μm can be prepared and bonded to the frame 7a to form the lattice section 7.

[0031] This workpiece separator is interposed between the adsorbed workpiece and the electrostatic adsorbent, and after the voltage application to the adsorption electrode is stopped, it assists in separating the workpiece from the workpiece adsorption surface. Specifically, when the workpiece is adsorbed, the workpiece separator is in close contact with the electrostatic adsorbent, as shown in Figures 1 to 4 above. On the other hand, when the workpiece is de-chucking, the workpiece separator is moved relatively away from the electrostatic adsorbent to assist in the separation (de-chucking) of the workpiece. In this case, for example, as shown in Figure 6(a), a drive device (not shown) such as a motor or air cylinder may be used to move the entire workpiece separator 5 away so that it is at a certain distance, thereby separating the workpiece w from the workpiece adsorption surface 1a of the electrostatic adsorbent 1. Alternatively, as shown in Figure 6(b), the workpiece separator 5 may be tilted by a drive device (not shown) while fixing a part (one side) on an axis, thereby separating the workpiece w from the workpiece adsorption surface 1a. After that, the separation of the workpiece is completed when the workpiece separator moves away from the workpiece.

[0032] Furthermore, as shown in Figure 7, the workpiece separator 5 may be housed in a groove 10 formed in the gap between the adsorption electrodes 4 of the electrostatic adsorbent 1 (the gap between adsorption electrodes 4a and 4b), so that the workpiece w and the workpiece adsorption surface 1a are in close contact. This prevents a portion of the workpiece adsorption force generated by the electrostatic adsorbent 1 from being impaired (reduced) by the workpiece separator 5.

[0033] Furthermore, the electrostatic adsorbent in the present invention only needs to have an adsorption electrode inside and be capable of generating workpiece adsorption force by applying an external voltage to the adsorption electrode. For example, known types can be used, such as those that have an adsorption electrode between an upper insulating layer and a lower insulating layer, with the upper insulating layer side being the workpiece adsorption surface. The upper insulating layer and lower insulating layer can be formed using, for example, a resin film or ceramics. The adsorption electrode can be made of metal foil such as copper or aluminum, or formed by sputtering or ion plating, or by etching a metal layer formed by thermal spraying of a metal material or printing conductive ink to create a predetermined shape. In particular, as an electrostatic adsorbent that has high insulating properties such as paper, cloth, or resin film and can generate a high workpiece adsorption force for thin, sheet-like workpieces, those described in Publication No. 2020 / 027246 are preferably used. It is possible.

[0034] In other words, the upper insulating layer has a volume resistivity of 1 × 10⁻⁶. 10 ~10 13 It is best to use a resin film with a volume resistivity of Ω·cm. If the volume resistivity is within this range, sufficient workpiece adsorption force can be achieved for the workpieces described above. In particular, a volume resistivity of 1 × 10⁻⁶ is desirable. 10 If the resistance is less than Ω·cm, the suction force to these workpieces will increase, but leakage current may occur between the workpiece suction surface and the workpiece, potentially causing damage to workpieces such as paper or cloth.

[0035] Furthermore, the resin film forming the upper insulating layer preferably has a tensile modulus (Young's modulus) of 1 MPa or more and less than 100 MPa. Although the detailed principle is not clear, the workpieces to be adsorbed in this invention are often relatively thin and soft, including those described above. In order to be able to adhere to such workpieces, it is desirable that the resin film forming the upper insulating layer have a tensile modulus (Young's modulus) within the above range. This is also advantageous when the upper insulating layer is curved to create a curved surface for adsorbing the workpiece. Moreover, from the viewpoint of ensuring insulation, flexibility, conformability to the workpiece, and durability, the thickness of this resin film preferably is 20 to 200 μm.

[0036] Examples of such resin films include polyimide, polyethylene terephthalate (PET), nylon, polypropylene, polyurethane, flexible polyvinyl chloride, and polyvinylidene chloride. These may be processed by mixing in fillers to adjust properties such as conductivity. In particular, polyurethane and flexible polyvinyl chloride are preferred in order to achieve the above-mentioned range for volume resistivity and tensile modulus.

[0037] Furthermore, while the lower insulating layer may be made of the same resin film as described for the upper insulating layer, or a different insulating material may be used, from the viewpoint of preventing the current that should ideally flow between the workpiece and the resin film forming the upper insulating layer from flowing to the lower insulating layer, it is preferable that the lower insulating layer be made of a material with the same volume resistivity as the resin film forming the upper insulating layer, or a material with a greater volume resistivity. Also, from the viewpoint of ensuring the flexibility of the electrostatic adsorbent as a whole, it is preferable that the lower insulating layer also has a tensile modulus (Young's modulus) similar to that of the resin film forming the upper insulating layer. Moreover, for the same reasons as for the upper insulating layer, the thickness of the lower insulating layer is preferably 20 to 200 μm.

[0038] The insulating material forming the lower insulating layer is not particularly limited, but the same material as the resin film forming the upper insulating layer, or ceramics such as aluminum nitride or alumina can be used. Preferably, as with the resin film forming the upper insulating layer, polyimide, polyethylene terephthalate (PET), nylon, polypropylene, polyurethane, flexible polyvinyl chloride, polyvinylidene chloride, etc., can be used, and these may be processed by mixing in fillers to adjust properties such as conductivity. More preferably, as with the resin film forming the upper insulating layer, polyurethane or flexible polyvinyl chloride is preferred from the viewpoint of keeping the volume resistivity and tensile modulus within a predetermined range, and even more preferably, flexible polyvinyl chloride is used.

[0039] Furthermore, regarding the adsorption electrode, bipolar types to which voltages with opposite polarities are applied, and unipolar types to which voltage is applied to the adsorption electrode while the workpiece is grounded are generally known. In the present invention, either of these can be used, but since the workpiece must be grounded as described above in the case of the unipolar type, it is preferable to use a bipolar adsorption electrode. The material for forming the adsorption electrode is as described above. Furthermore, there are no particular restrictions on its thickness, but considering the risk of breakage due to deformation of the electrostatic adsorbent, or conversely, the fact that flexibility is hindered if it is too thick, it is preferable that the thickness of the adsorption electrode be 1 to 20 μm.

[0040] Here, examples of bipolar adsorption electrodes include a pair of flat or semicircular adsorption electrodes, as well as a pair of adsorption electrodes having a comb-like or mesh-like pattern. Preferably, as shown in Figure 8, a pair of comb-shaped electrodes 14a and 14b are formed by interlocking the comb teeth on the same plane while maintaining a constant distance from each other. By forming a bipolar adsorption electrode 14 with such comb-shaped electrodes 14a and 14b, a strong workpiece adsorption force can be achieved even when the workpiece is made of paper, cloth, resin film, etc. That is, since these workpieces are insulators, the Coulomb force that is predominantly generated when conductors or semiconductors are to be adsorbed is reduced. However, by using a pair of comb-shaped electrodes as described above as adsorption electrodes, a gradient force is generated between the insulating workpiece and the electrodes, and a strong adsorption force can be obtained.

[0041] Furthermore, when obtaining an electrostatic adsorbent using these upper insulating layer, lower insulating layer, and adsorption electrode, the adsorption electrode is sandwiched between the upper and lower insulating layers so that it is not exposed. Specifically, for example, the adsorption electrode may be positioned between the upper and lower insulating layers and these may be integrally formed by thermocompression bonding, or they may be integrally formed using bonding sheets, adhesives, or other adhesives. In this case, as described above, a conductive shielding member 8 may be provided on the electrostatic adsorbent 1. For example, the conductive shielding member 8 may be attached to a predetermined position on the upper insulating layer 2 that forms the workpiece adsorption surface 1a, or the upper insulating layer 2 may be formed in multiple layers, and the conductive shielding member 8 may be interposed between the upper insulating layers 2 to form an integral part with the adsorption electrode 4 and the lower insulating layer 3.

[0042] Furthermore, there are no particular restrictions on applying voltage to the adsorption electrodes of the electrostatic adsorbent, and known methods can be used. For example, a power supply can be connected to the adsorption electrodes via connection terminals or switches. In this case, when adsorbing a workpiece made of a sheet-like insulating material such as paper, cloth, or resin film, it is preferable to use a power supply capable of generating a high DC voltage. The potential difference to be generated can be approximately ±100 to ±5000V, and a boost circuit (high voltage generation circuit) that can boost the voltage to a predetermined level may be provided as needed. In addition, the polarity of the voltage applied to the bipolar adsorption electrodes may be reversed with each cycle operation from workpiece adsorption to de-chuck.

[0043] Furthermore, there are no particular limitations on the workpieces that the workpiece adsorption device of the present invention can target. In addition to semiconductors and conductors, sheet-like insulating materials such as paper, cloth, and resin films as described above, as well as bundles of fibers, can be adsorbed. Also, for sheet-like workpieces, multiple items may be adsorbed and handled at once. For example, an insulating material with a volume resistivity of 1 × 10⁻⁶ 12 ~10 14 Even materials with a charge of approximately Ω·cm or a thickness of 2 mm or less can be used as suitable workpieces in this invention because the influence of residual charge can be minimized. In particular, even extremely thin materials of about 0.005 to 0.5 mm can be adsorbed and detached as workpieces. [Examples]

[0044] The present invention will be described more specifically below based on examples, but the present invention is not limited to these examples.

[0045] (Example 1) <Preparation of test electrostatic adsorbents> In this example, a test electrostatic adsorbent was fabricated, and experiments were conducted to confirm the change in surface potential (charge) under various conditions. First, to obtain a test electrostatic adsorbent, a double-sided film tape (product name: Kapton® Double-Sided Tape 760H, manufactured by Teraoka Seisakusho Co., Ltd.) was prepared, which consisted of a 25 μm thick polyimide film with a silicone-based adhesive protected by release paper (film separator) on both sides. An 18 μm thick copper foil was then attached to the silicone-based adhesive on one side. Next, only the copper foil portion was cut using a cutting plotter (Graphtec Corporation FC2250-180VC). A pair of comb-shaped electrodes 24a and 24b were cut out and formed as shown in Figure 9(a). At this time, the width of each comb tooth portion (electrode width) of the comb-shaped electrodes 24a and 24b was 8 mm, and the spacing between the comb teeth portions (pitch) was 4 mm.

[0046] Next, a 5mm thick plastic sheet (low-foaming PVC sheet) (product name: Grafoam GF-5, manufactured by Kinugawa Co., Ltd.) was laminated to the silicone-based adhesive on the other side of the film double-sided tape as a base material (support material). Furthermore, a 100μm thick flexible polyvinyl chloride film was layered over the adsorption electrode 24 formed on the film double-sided tape and laminated using a laminator and roller. This flexible polyvinyl chloride film has a volume resistivity of 1 × 10⁻⁶ 10 The resistance was Ω·cm, and the tensile modulus (Young's modulus) was 20-30 MPa. The volume resistivity of the flexible polyvinyl chloride film at this time was measured by the double-ring electrode method (IEC60093, ASTM D257, JIS K6911, JIS K6271). In this way, as shown in Figure 9(b), a test electrostatic adsorbent measuring 100 mm in length × 125 mm in width was prepared, having a polyimide film (lower insulating layer 13), comb-shaped electrodes 24a and 24b (adsorption electrodes 24), and a flexible polyvinyl chloride film (upper insulating layer) 12 on a plastic plate (base substrate 19).

[0047] <Surface potential measurement of test electrostatic adsorbents> For the electrostatic adsorbent obtained above, a voltage of ±1500V was applied to its comb-shaped electrodes 24a and 24b from a power supply (not shown) to measure the surface potential of the soft polyvinyl chloride film that was in contact with the workpiece adsorption surface. A KSD-3000 digital low-potential measuring instrument manufactured by Kasuga Electric Co., Ltd. was used as the surface potential meter. This surface potential meter is equipped with a vibrating surface potential sensor with a surface potential measurement area of ​​20 mm x 20 mm at the tip of the probe, and measures the surface potential of the workpiece adsorption surface of the target electrostatic adsorbent at a measurement reference distance (height) of 10 mm.

[0048] Here, the surface potential of the workpiece adsorption surface was measured for the comb-shaped electrodes 24a and 24b at 3 mm intervals in a direction perpendicular to the longitudinal direction of the comb portion. Specifically, for the four comb portions within the region Y enclosed by the dashed line in Figure 9(a), starting from P1, P 15 Measurements were taken at 3 mm intervals along a straight line P with the endpoint at P1. As a result, the comb-shaped portions of the negative electrode's comb-shaped electrode 24b and the positive electrode's comb-shaped electrode 24a are arranged alternately on the straight line P, with P1 being the center of the electrode width of the comb-shaped portion of the comb-shaped electrode 24b. The surface potential was measured three times at a single measurement point, and the average value was calculated.

[0049] And when measuring the surface potential along the above straight line P, When measuring the workpiece adsorption surface of a test electrostatic adsorbent directly, <ii>When measuring by placing an aluminum foil measuring 25 mm wide x 100 mm long x 20 μm thick on the workpiece adsorption surface, <iii>Width 22mm x Length 90mm When measuring with polyester cloth (virtual workpiece) placed on the workpiece suction surface, and <iv>The surface potential was measured in four patterns: when the above-mentioned aluminum foil was placed on the workpiece adsorption surface, and the above-mentioned polyester cloth was placed on top of it. The results are shown in Figure 10. Note that the aluminum foil was connected to ground when it was placed.

[0050] Figure 10 The results show that on the workpiece adsorption surface of the test electrostatic adsorbent, the surface potential is highest at the widthwise center of the comb-shaped electrodes 24a and 24b, and the gap between adjacent comb-shaped portions is smallest (zero). <iii>Surface potential of polyester fabric The same was true in that case. In contrast, <ii>In this case, on the surface of the aluminum foil mimicking a conductive shielding material, the surface potential did not rise even at the comb-shaped portions of the comb-shaped electrodes 24a and 24b, and remained almost zero. This is because <iv>The same result was observed with the surface potential of a polyester cloth placed on top of aluminum foil.

[0051] These results suggest that in gaps between adjacent adsorption electrodes or in areas with conductive shielding materials such as aluminum foil, the surface potential does not rise even when a voltage is applied to the adsorption electrodes. Therefore, it can be said that charging of the workpiece or workpiece separator can be prevented in such locations.

[0052] (Example 2) In this embodiment, a test electrostatic adsorbent was prepared by embedding the aluminum foil, which was placed on the workpiece adsorption surface in the previous Example 1, inside the electrostatic adsorbent. Specifically, an aluminum foil measuring 25 mm wide × 100 mm long × 20 μm thick was placed on top of the flexible polyvinyl chloride film of the test electrostatic adsorbent prepared in Example 1, and then another flexible polyvinyl chloride film of the same thickness as used in Example 1 (100 μm) was placed on top of it and bonded together using a laminator and roller. At this time, the aluminum foil was positioned perpendicular to the longitudinal direction of the comb-tooth portions of the comb-shaped electrodes 24a and 24b. In this way, a test electrostatic adsorbent was prepared with the above-mentioned aluminum foil, which corresponds to a conductive shielding member, between two flexible polyvinyl chloride films that form the upper insulating layer. This aluminum foil was also connected to ground.

[0053] The electrostatic adsorbent obtained in this manner was measured in the same manner as in Example 1, with the portion containing the aluminum foil included in region Y. When measuring the surface potential along the straight line P, <v>When measuring the workpiece adsorption surface in the portion without aluminum foil, and <vi>Surface potential was measured in two ways: when measuring the workpiece adsorption surface of the portion containing aluminum foil. The results are shown in Figure 11.

[0054] As can be seen from Figure 11, <v>In contrast, the surface potential is highest at the center in the width direction of the comb-shaped electrodes 24a and 24b, and the gap between adjacent comb-shaped electrodes is smallest at the center of the gap between them. <vi>In this case, the surface potential did not increase even at the comb-shaped portions of the comb-shaped electrodes 24a and 24b, remaining at a value close to zero, showing the same results as in Example 1.

[0055] As described above, the workpiece adsorption device according to the present invention can prevent dielectric polarization and electrostatic induction of the workpiece separator when adsorbing a workpiece, making it possible to dechuck (separate) the adsorbed workpiece quickly and reliably. In particular, since the influence of residual charge on the workpiece and workpiece separator can be eliminated as much as possible in the present invention, it can be suitably used in situations where thin workpieces such as paper, cloth, and resin film are transported, and a versatile workpiece adsorption device can be realized that is less affected by the type and shape of the workpiece or the surrounding environment such as humidity. [Explanation of symbols]

[0056] 1: Electrostatic adsorbent, 1a: Workpiece adsorption surface, 2,12: Upper insulating layer, 3,13: Lower insulating layer, 4: Adsorption electrode, 4a,4b,14a,14b,24a,24b: (Bipolar) adsorption electrode, 5: Workpiece separator, 6: Opening, 7: Grid section, 7a: Frame, 7b,7b': Connecting section, 8: Conductive shielding member, 9,19: Support material, 10: Groove section.< / vi> < / v> < / vi> < / v> < / iv> < / ii> < / iii> < / iv> < / iii> < / ii>

Claims

1. A workpiece adsorption device comprising: an electrostatic adsorbent having an internal adsorption electrode that generates a workpiece adsorption force when a voltage is applied, thereby adsorbing a workpiece onto the workpiece adsorption surface; and a workpiece separator interposed between the adsorbed workpiece and the electrostatic adsorbent to assist in separating the workpiece from the workpiece adsorption surface after the application of voltage to the adsorption electrode is stopped, The workpiece separator has a plurality of openings for applying the workpiece suction force generated on the workpiece suction surface to the workpiece, and the openings are partitioned by a grid so that they are substantially uniformly located within the plane of the workpiece separator, and the workpiece suction device is characterized in that, when viewed from the workpiece side in plan view during workpiece suction, the suction electrodes of the electrostatic suction body and the grid of the workpiece separator do not face each other.

2. The workpiece adsorption apparatus according to claim 1, wherein the grid portion of the workpiece separator is arranged to surround the adsorption electrode of the electrostatic adsorbent, and when viewed from the workpiece side in plan view during workpiece adsorption, the adsorption electrode of the electrostatic adsorbent and the grid portion of the workpiece separator do not face each other.

3. A workpiece adsorption device comprising: an electrostatic adsorbent having an internal adsorption electrode that generates a workpiece adsorption force when a voltage is applied, thereby adsorbing a workpiece onto the workpiece adsorption surface; and a workpiece separator interposed between the adsorbed workpiece and the electrostatic adsorbent to assist in separating the workpiece from the workpiece adsorption surface after the application of voltage to the adsorption electrode is stopped, A workpiece adsorption device characterized in that the workpiece separator has a plurality of openings for applying the workpiece adsorption force generated on the workpiece adsorption surface to the workpiece, and the openings are partitioned by a grid so that they are substantially uniformly located within the surface of the workpiece separator, and a conductive shielding member is interposed between the grid of the workpiece separator and the adsorption electrode of the electrostatic adsorbent.

4. The workpiece adsorption device according to claim 3, wherein the conductive shielding member is disposed on the electrostatic adsorbent.

5. A workpiece adsorption device comprising: an electrostatic adsorbent having an internal adsorption electrode that generates a workpiece adsorption force when a voltage is applied, thereby adsorbing a workpiece onto the workpiece adsorption surface; and a workpiece separator interposed between the adsorbed workpiece and the electrostatic adsorbent to assist in separating the workpiece from the workpiece adsorption surface after the application of voltage to the adsorption electrode is stopped, The workpiece separator has a plurality of openings for applying the workpiece suction force generated on the workpiece suction surface to the workpiece, and the openings are partitioned by a grid so that they are substantially uniformly located within the plane of the workpiece separator, and when viewed from the workpiece side during workpiece suction, the suction electrodes of the electrostatic adsorbent and the grid of the workpiece separator do not face each other, and a conductive shielding member is interposed between the grid of the workpiece separator and the suction electrodes of the electrostatic adsorbent, characterized in that a workpiece suction device.

6. The workpiece adsorption device according to any one of claims 3 to 5, wherein the conductive shielding member is connected to earth.

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