Electrostatically levitated conveyance apparatus and electrode thereof for electrostatic levitation

• US 5,789,843 A
• Filed: 10/30/1995
• Issued: 08/04/1998
• Est. Priority Date: 03/18/1994
• Status: Expired due to Fees

• Current Assignee: Kanagawa Academy of Science and Technology, Mitsubishi Materials Corporation
• Original Assignee: Kanagawa Academy of Science and Technology, Mitsubishi Materials Corporation
• Inventors: Kanemoto, Manabu, Jin, Ju, Higuchi, Toshiro
• Primary Examiner(s): Laballe, Clayton E.
• Application Number:
  US08/535,246
• Time in Patent Office: 1,009 Days
• Field of Search: 310/308, 310/309
• US Class Current: 310/309
• CPC Class Codes: B65G 54/02 electrostatic, electric, or magnetic
• CPC Class Codes: B65H 3/18 using electrostatic force
• CPC Class Codes: B65H 5/004 using electrostatic force
• CPC Class Codes: H01L 21/67784 using air tracks
• CPC Class Codes: H01L 21/6833 Details of electrostatic chucks
• CPC Class Codes: H01L 21/6838 with gripping and holding devices using a vacuum; Bernoulli devices
• CPC Class Codes: H02N 13/00 Clutches or holding devices using electrostatic attraction, e.g. using Johnson-Rahbek effect

Abstract

An electrostatic levitating electrode (10) is split into four equal segments on a circular insulating substrate (4) with isolating strips (11a, 11b) interposed between them. A positive voltage and a negative voltage are alternately applied to these four electrodes (10a, 10b, 10c, 10d), which are sector-shaped. In order to prevent the concentration of electric charge in such case, the corner portions of the sector-shaped electrodes (10a, 10b, 10c, 10d) are formed to have roundness (13). Furthermore, a lead wire (12a) is connected to the outer side of the sector-shaped electrode (10a), a lead wire (12b) is connected to the outer side of the sector-shaped electrode (10b), a lead wire (12c) is connected to the outer side of sector-shaped electrode (10c), and a lead wire (12d) is connected to the outer side of sector-shaped electrode (10d). Accordingly, the maximum attraction force and levitational rigidity are increased without damage to electrodes at lead portions and it possible to convey a levitated body with accuracy.

Claims

1. An electrostatically levitated conveyance apparatus using DC electrostatic attraction forces from a single side, comprising:

(a) an electrostatic levitating electrode arrangement having an insulating substrate, an even plurality of electrostatic levitating electrodes which are separated and arranged uniformly on a single side of the insulating substrate, lead wires extending out from all of the electrodes from an outer side or underside thereof, and means for energizing alternate electrodes of said even plurality of electrodes through said lead wires with respective positive and negative voltages so that each pair of adjacent electrodes are energized with opposite polarity voltages;

(b) a levitated body opposing said electrostatic levitating electrode arrangement;

(c) a plurality of displacement sensors for sensing gaps between said respective electrostatic levitating electrodes and the levitated body; and

(d) a controller for controlling the voltages applied to said electrostatic levitating electrodes such that said levitated body is attracted, held and conveyed without contact by electrostatic attraction forces owing to application of the positive and negative DC voltages to said electrostatic levitating electrodes, the levitated body being released from said electrostatic levitating electrodes by cutting off the voltages to said electrostatic levitating electrodes when the levitated body arrives at a predetermined position.

2. An electrostatic levitating apparatus according to claim 1, wherein said levitated body is plate-shaped.

3. A DC electrostatic levitating electrode arrangement of an electrostatically levitated conveyance apparatus, comprising:

(a) an insulating substrate;

(b) an even plurality of electrodes which are separated and arranged uniformly on a single side surface of the insulating substrate;

(c) lead wires extending out from all of said electrodes from an outer side or underside thereof; and

(d) means for energizing alternate electrodes of said even plurality of electrodes through said lead wires with respective positive and negative DC voltages which have magnitudes controlled inversely in accordance with variations from a predetermined spacing between an article being levitated by said electrodes and said corresponding electrodes.

4. An electrostatic levitating electrode arrangement according to claim 3, wherein said even plurality of electrodes includes four electrodes.

5. An electrostatic levitating electrode arrangement according to claim 3, wherein said even plurality of electrodes together form a circular shape pattern.

6. An electrostatic levitating electrode arrangement according to claim 3, wherein said electrodes are sector-shaped.

7. An electrostatic levitating electrode arrangement according to claim 3, wherein said electrode arrangement has a hole at the center thereof.

8. An electrostatic levitating electrode arrangement according to claim 3, wherein said even plurality of electrodes together from a rectangular shape pattern.

9. An electrostatic levitating electrode arrangement according to claim 8, wherein said rectangular pattern of electrodes is square in shape.

10. An electrostatic levitating electrode arrangement according to claim 8, wherein said electrodes are rectangular in shape.

11. An electrostatic levitating electrode arrangement according to claim 3, wherein corner portions of said electrodes are formed to have roundness.