# US 8,542,262 B2 · Light emitting element array, drive circuit, optical print head, and image forming apparatus

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- Number: US 8,542,262 B2
- Document ID: US8542262B2
- Status: Granted
- Kind: B2
- Application number: 12/615,523
- Filed: 2009-11-10
- Published: 2010-05-20
- Granted: 2013-09-24
- Earliest claimed: 2008-11-14
- Assignees: Oki Data Corporation
- Applicants: Akira Nagumo
- Inventors: Akira Nagumo
- Web page: https://patentgrep.com/patent/US8542262B2

## CPC

- G03G 15/326: {by application of light, e.g. using a LED array}
- B41J 2/45: using light-emitting diode {[LED] or laser} arrays
- G03G 15/04054: {by LED arrays}
- H10W 72/5445: {being orthogonal to a side surface of the chip, e.g. parallel arrangements}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A light emitting element array includes a plurality of light emitting elements each having a first terminal, a second terminal, and a third terminal. The light emitting elements are arranged next to each other to form a group. The first terminal receives a drive signal, the second terminal is connected to ground, and the third terminal has a threshold voltage or a threshold current controllable from outside so that the light emitting elements are driven in a time division way.

## Claims

### Claim 1

A drive circuit for driving a plurality of light emitting thyristors each including an anode for receiving a drive signal to drive the light emitting thyristor, a cathode connected to ground, and a gate for receiving a control signal to drive the light emitting thyristor in a time division way, comprising:
a plurality of drive elements for supplying the drive signal to the anodes of the light emitting thyristors;
a plurality of common base lines for flowing the control signal to control on/off of the light emitting thyristors; and
a plurality of individual circuits connected to the common base lines for supplying the control signal to the gates of the light emitting thyristors, said individual circuits having a function of shifting a level of the control signal,
wherein each of said individual circuits is formed of an n-type conductive switch element having a first switch terminal connected to one of the common base lines, a second switch terminal connected to the gate, and a third switch terminal connected to the second switch terminal for controlling a conductive state between the first switch terminal and the second switch terminal.

### Claim 2 (depends on 1)

The drive circuit according to claim 1, wherein each of said individual circuits is an N-channel MOS transistor having a source as the first switch terminal, a drain as the second switch terminal, and a gate as the third switch terminal.

### Claim 3 (depends on 1)

An optical print head comprising,
a light emitting thyristor array including a plurality of light emitting thyristors each including an anode for receiving a drive signal to drive the light emitting thyristor, a cathode connected to ground, and a gate for receiving a control signal to drive the light emitting thyristor in a time division way;
a lens array for collecting light emitted from the light emitting element thyristor array; and
the drive circuit according to claim 1.

### Claim 4 (depends on 3)

An image forming apparatus comprising the optical print head according to claim 3 and a photosensitive member arranged to face the optical print head.

### Claim 5

A drive circuit for driving a plurality of light emitting thyristors each including an anode for receiving a drive signal to drive the light emitting thyristor, a cathode connected to ground, and a gate for receiving a control signal to drive the light emitting thyristor in a time division way, comprising:
a plurality of drive elements for supplying the drive signal to the anodes of the light emitting thyristors;
a plurality of common base lines for flowing the control signal to control on/off of the light emitting thyristors; and
a plurality of individual circuits connected to the common base lines for supplying the control signal to the gates of the light emitting thyristors, said individual circuits having a function of shifting a level of the control signal,
wherein each of said individual circuits is formed of a p-type conductive switch element having a first switch terminal connected to the gate, a second switch terminal connected to one of the common base lines, and a third switch terminal connected to the second switch terminal for controlling a conductive state between the first switch terminal and the second switch terminal.

### Claim 6 (depends on 5)

The drive circuit according to claim 5, wherein each of said individual circuits is an P-channel MOS transistor having a source as the first switch terminal, a drain as the second switch terminal, and a gate as the third switch terminal.

### Claim 7 (depends on 5)

An optical print head comprising,
a light emitting thyristor array including a plurality of light emitting thyristors each including an anode for receiving a drive signal to drive the light emitting thyristor, a cathode connected to ground, and a gate for receiving a control signal to drive the light emitting thyristor in a time division way;
a lens array for collecting light emitted from the light emitting element thyristor array; and
the drive circuit according to claim 5.

### Claim 8 (depends on 7)

An image forming apparatus comprising the optical print head according to claim 7 and a photosensitive member arranged to face the optical print head.