# US 5,708,520 A · Rotating polygon mirror driving apparatus

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- Number: US 5,708,520 A
- Document ID: US5708520A
- Status: Granted
- Kind: A
- Application number: 08/661,644
- Filed: 1996-06-11
- Granted: 1998-01-13
- Earliest claimed: 1992-12-15
- Assignees: Matsushita Electric Industrial Co., Ltd.
- Inventors: Takao Yoshitsugu; Koichiro Ohata; Tsuyoshi Kano
- Web page: https://patentgrep.com/patent/US5708520A

## CPC

- G02B 26/121: {Mechanical drive devices for polygonal mirrors}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A rotating polygon mirror driving apparatus has a rotor having a rotating polygon mirror fixed thereto, a rotational shaft and a rotor magnet; a bracket having a base plate provided opposite to the rotor magnet and a collar forming a bearing holding portion of a resin outserted to the base plate and made; and a bearing fitted to the bracket so as to support the rotational shaft. The driving apparatus can be decreased in cost and thickness while maintaining excellent rotational precision and mechanical precision.

## Claims

### Claim 1

A rotating polygon mirror driving apparatus comprising:
a rotor having a rotating polygon mirror fixed thereto, a rotational shaft and a rotor magnet;
a bracket comprising (i) a base plate provided opposite to said rotor magnet, (ii) a cylindrical collar as a bearing holding portion, said cylindrical collar including a first portion comprising a resin material and having a cylindrical axis, and (iii) an apparatus mounting portion extending in a direction at right angles to the cylindrical axis of said collar, said mounting portion having a second portion comprising said resin material, said collar and said mounting portion being formed on said base plate by an outsert of said resin material; and
a bearing comprising a bearing sleeve and fitted to said collar so as to rotatably support said rotational shaft.

### Claim 2 (depends on 1)

A rotating polygon mirror driving apparatus according to claim 1, wherein said bearing is a dynamic pressure fluid bearing having a herringbone groove formed in one of said rotational shaft and said bearing sleeve for generating dynamic pressure.

### Claim 3 (depends on 1)

A rotating polygon mirror driving apparatus according to claim 1, wherein said base plate comprises a magnetic material and forms a magnetic path together with said rotor magnet.

### Claim 4 (depends on 1)

A rotating polygon mirror driving apparatus according to claim 1, wherein the coefficient of linear expansion of said resin ranges from 10.times.10.sup.-6 to 25.times.10.sup.-6 and is between the coefficients of linear expansion of said bearing sleeve and said base plate.

### Claim 5 (depends on 1)

A rotating polygon mirror driving apparatus according to claim 1, wherein said apparatus mounting portion is formed on a side of said base plate which is remote from said rotor magnet.