Semiconductor laser driver and image forming apparatus incorporating same

Patent metadata

Field	Value
Publication number	US-9983503-B2
Application number	US-201715405705-A
Country	US
Kind code	B2
Filing date	Jan 13, 2017
Priority date	Feb 1, 2016
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A semiconductor laser driver and an image forming apparatus incorporating the semiconductor laser driver. The semiconductor laser driver includes a light source including a plurality of laser-beam source units disposed in a sub-scanning direction that serves as a group direction, the laser-beam source units having a plurality of groups arranged in a main scanning direction, each of the laser-beam source units emitting a laser beam of a light quantity dependent upon a driving current, a shading corrector to correct, according to at least one shading correction value, the driving current given to the laser-beam source units for each of the groups, and a light quantity adjuster to adjust the driving current according to a light-quantity adjustment value for the laser-beam source units. The image forming apparatus includes a semiconductor laser drive circuit, and the semiconductor laser driver that serves as the semiconductor laser driver.

First claim

What is claimed is:

1. A semiconductor laser driver comprising:
a light source including a plurality of laser-beam emitters that are arranged into a plurality of groups, each group including laser-beam emitters disposed in a sub-scanning direction that serves as a group direction, the plurality of groups being arranged in a main scanning direction different from the sub-scanning direction, and each of the laser-beam emitters being configured to emit a laser beam of a light quantity dependent upon a respective driving current;
a shading correction circuit configured to generate, according to at least one shading correction value, reference driving currents for the laser-beam emitters in one of the groups, respectively; and
a light quantity adjuster adjustment circuit configured to adjust a respective one of the reference driving currents according to a light-quantity adjustment value as a driving current for one of the laser-beam emitters in the one of the groups.

2. The semiconductor laser driver according to claim 1 , wherein
the shading correction circuit comprises:
a first shading corrector configured to generate group reference currents for a part of or all of the plurality of groups, respectively; and
a second shading corrector configured to generate the reference driving currents for the laser-beam emitters in the one of the groups based on a respective one of the group reference currents,

wherein the first shading corrector and the second shading corrector are coupled in series.

3. The semiconductor laser driver according to claim 2 , wherein
the at least one shading correction value comprises a first shading correction value and a second shading correction value,
the first shading corrector is configured to generate the group reference currents according to the first shading correction value that is greater than the second shading correction value, and
the second shading corrector is configured to generate the reference driving currents according to the second shading correction value.

4. The semiconductor laser driver according to claim 2 , wherein
the second shading corrector is configured to adjust the driving current for a particular laser-beam emitter at a rate faster than a rate at which the first shading corrector is configured to adjust the driving current.

5. The semiconductor laser driver according to claim 2 , wherein
the first shading corrector and the second shading corrector are implemented using a digital-analog converter.

6. The semiconductor laser driver according to claim 5 , wherein
the laser-beam emitters are formed on a semiconductor device, and
the shading correction circuit is formed on the semiconductor device.

7. An image forming apparatus comprising:
a semiconductor laser drive circuit to form an image by irradiating a photoconductor with laser beams according to image data; and
the semiconductor laser driver according to claim 6 .

8. The semiconductor laser driver according to claim 1 , wherein
the light quantity adjustment circuit and the shading correction circuit are implemented using a digital-analog converter.

9. The semiconductor laser driver according to claim 1 , wherein
the laser-beam emitters are formed on a semiconductor device, and
the shading correction circuit is formed on the semiconductor device.

10. An image forming apparatus comprising:
a semiconductor laser drive circuit to form an image by irradiating a photoconductor with laser beams according to image data; and
the semiconductor laser driver according to claim 9 .

11. An image forming apparatus comprising:
a semiconductor laser drive circuit configured to form an image by irradiating a photoconductor with laser beams according to image data; and
a semiconductor laser driver comprising
a light source including a plurality of laser-beam emitters that are arranged into a plurality of groups, each group including laser-beam emitters disposed in a sub-scanning direction that serves as a group direction, the plurality of groups being arranged in a main scanning direction different from the sub-scanning direction, and each of the laser-beam emitters being configured to emit a respective one of the laser beams of a light quantity dependent upon a respective driving current,
a shading correction circuit configured to generate, according to at least one shading correction value, reference driving currents for the laser-beam emitters in one of the groups, respectively, and
a light quantity adjustment circuit configured to adjust a respective one of the driving currents according to a light-quantity adjustment value as a driving current for the laser-beam emitters in the one of the groups.

12. An image forming apparatus comprising:
a semiconductor laser drive circuit to form an image by irradiating a photoconductor with laser beam according to image data; and
a semiconductor laser driver comprising
a light source including a plurality of laser-beam source units disposed in a sub-scanning direction that serves as a group direction, the laser-beam source units having a plurality of groups arranged in a main scanning direction, each of the laser-beam source units emitting a laser beam of a light quantity dependent upon a driving current,
a shading corrector to correct, according to at least one shading correction value, the driving current given to the laser-beam source units for each of the groups, and
a light quantity adjuster to adjust the driving current according to a light-quantity adjustment value for the laser-beam source units,

wherein
the shading corrector includes
a first shading corrector to simultaneously perform shading correction on the driving current supplied to a part of or all of the plurality of laser-beam source units, and
a second shading corrector to perform shading correction on the driving current supplied to the laser-beam source units for each of the groups,

the first shading corrector and the second shading corrector are coupled in series, and
the first shading corrector and the second shading corrector use a digital-analog converter.

Assignees

• Kamatani Tomohiko
• Ricoh Co Ltd

Inventors

• Kamatani Tomohiko

Classifications

• H04N1/40037

  the reproducing element being a laser · CPC title

• G03G15/043 Primary

  with means for controlling illumination or exposure (G03G15/041 takes precedence) · CPC title

• H04N1/40031

  for a plurality of reproducing elements simultaneously · CPC title

• H04N1/4015

  of the reproducing head · CPC title

• H04N1/295

  Circuits or arrangements for the control thereof, e.g. using a programmed control device, according to a measured quantity · CPC title