LIGHT SOURCE DRIVE DEVICE, OPTICAL SCANNING DEVICE AND IMAGE FORMING APPARATUS

• US 20120293783A1
• Filed: 05/16/2012
• Published: 11/22/2012
• Est. Priority Date: 05/20/2011
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Ishida, Masaaki, Omori, Atsufumi, Fujita, Hayato
• Granted Patent: US 9,155,148 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G02B 26/127 Adaptive control of the scanning light beam, e.g. using the feedback from one or more detectors G02B27/0031 takes precedence
• CPC Class Codes: G03B 27/54 Lamp housings; Illuminating means
• CPC Class Codes: H04N 1/053 in main scanning direction, e.g. synchronisation of line start or picture elements in a line
• CPC Class Codes: H04N 1/1135 for the main-scan only
• CPC Class Codes: H04N 2201/0471 using dedicated detectors
• CPC Class Codes: H04N 2201/04729 in the main-scan direction
• CPC Class Codes: H04N 2201/04732 Detecting at infrequent intervals, e.g. once or twice per line for main-scan control
• CPC Class Codes: H04N 2201/04744 by detecting the scanned beam or a reference beam
• CPC Class Codes: H04N 2201/04774 using a reference clock or oscillator H04N2201/04772 takes precedence
• CPC Class Codes: H04N 2201/04789 in the main-scan direction
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix

Abstract

A light source drive device includes a first current source which provides a predetermined current to a light source corresponding to a predetermined light output, and a second current source which provides an overshoot current to the light source synchronized with the predetermined current. A processor is configured to set an overshoot time during which the overshoot current is provided to the light source. Further, an overshoot current is set which is applied to the light source. The overshoot time is set so that the overshoot time based on the rising of the predetermined current to when a light emission of the light source is detected.

Claims

1. A light source drive device comprising:

a first current source which provides a predetermined current to a light source corresponding to a predetermined light output;

a second current source which provides an overshoot current to the light source synchronized with the predetermined current of the first current source, the overshoot current being an additional current which increases the current applied to the light source; and

a processor configured to perform;

setting an overshoot time during which the overshoot current is applied to the light source; and

setting an overshoot current which is applied to the light source,

wherein the overshoot time is set so that the overshoot time is smaller than a time period from the rising of the predetermined current to when a light emission of the light source is detected.

2. The light source drive device as claimed in claim 1,

wherein the setting of the overshoot current sets the overshoot current, after the overshoot time is set.

3. The light source drive device as claimed in claim 1, further comprising:

a light detector which receives emitted light from the light source and outputs a signal corresponding to an amount of the emitted light; and

an integrator which integrates the signal output from the light detecting device,

wherein the setting of the overshoot time detects the light emission when an integrated value obtained by the integrator becomes equal to or larger than an overshoot time threshold.

4. The light source drive device as claimed in claim 3, further comprising:

a pulse generator which outputs a selected pulse signal among plural pulse signals having different pulse width and drives the second current source based on the selected pulse signal,

wherein the setting of the overshoot time includes selecting one of the plural pulse signals in an order starting with a smaller pulse width, and

the setting of the overshoot time sets the overshoot time so that the overshoot time corresponds to a pulse signal whose pulse width is smaller than a pulse signal which causes a detection of the emitted light.

5. The light source drive device as claimed in claim 3 further comprising:

a memory which stores an emission pattern to drive the first current source providing the predetermined current to the light source,

wherein

the setting of the overshoot current includes selecting an overshoot current added to the predetermined current, in an order beginning with a smaller current value, and

the setting of the overshoot current sets the overshoot current when the integrated value obtained by the integrator becomes equal to or larger than a overshoot current threshold, as the predetermined current and the overshoot current are applied to the light source.

6. An optical scanning device that scans a scan target surface with light, the optical scanning device comprising:

a semiconductor laser;

the laser driving device according to claim 1 that drives the semiconductor laser;

a deflector that deflects light from the semiconductor laser; and

a scanning optical system that collects light deflected by the deflector on the scan target surface.

7. An image forming apparatus comprising:

at least one image carrier; and

at least one optical scanning device according to claim 6 that scans the at least one image carrier with light modulated according to image information.

8. A light source drive device, comprising:

a first current source which provides a predetermined current to a light source corresponding to a predetermined light output;

a second current source which provides an overshoot current to the light source synchronized with the predetermined current of the first current source, the overshoot current being an additional current which increases the current applied to the light source;

means for setting an overshoot time during which the overshoot current is applied to the light source; and

means for setting an overshoot current which is applied to the light source,

wherein the overshoot time is set so that the overshoot time is smaller than a time period from the rising of the predetermined current to when a light emission of the light source is detected.

9. The light source drive device as claimed in claim 8,

wherein the means for setting of the overshoot current sets the overshoot current, after the overshoot time is set.

10. The light source drive device as claimed in claim 8, further comprising:

a light detector which receives emitted light from the light source and outputs a signal corresponding to an amount of the emitted light; and

an integrator which integrates the signal output from the light detecting device,

wherein the means for setting of the overshoot time detects the light emission when an integrated value obtained by the integrator becomes equal to or larger than an overshoot time threshold.

11. The light source drive device as claimed in claim 10, further comprising:

a pulse generator which outputs a selected pulse signal among plural pulse signals having different pulse width and drives the second current source based on the selected pulse signal,

wherein the means for setting of the overshoot time includes selecting one of the plural pulse signals in an order starting with a smaller pulse width, and

the means for setting of the overshoot time sets the overshoot time so that the overshoot time corresponds to a pulse signal whose pulse width is smaller than a pulse signal which causes a detection of the emitted light.

12. The light source drive device as claimed in claim 10, further comprising:

a memory which stores an emission pattern to drive the first current source providing the predetermined current to the light source,

wherein

the means for setting of the overshoot current includes selecting an overshoot current added to the predetermined current, in an order beginning with a smaller current value, and

the means for setting of the overshoot current sets the overshoot current when the integrated value obtained by the integrator becomes equal to or larger than a overshoot current threshold, as the predetermined current and the overshoot current are applied to the light source.

13. A method of driving a light source, comprising:

setting an overshoot time during which an overshoot current is applied to the light source;

setting an overshoot current which is applied to the light source so that the overshoot time is smaller than a time period from the rising of the predetermined current to when a light emission of the light source is detected;

providing a predetermined current to the light source corresponding to a predetermined light output;

providing the overshoot current to the light source for the overshoot time, synchronized with the predetermined current of the first current source, the overshoot current being an additional current which increases the current applied to the light source.