OPTICAL SCANNING DEVICE HAVING A PLURALITY OF LIGHT SOURCES, OPTICAL SCANNING METHOD, PIXEL FORMING DEVICE, IMAGE FORMING APPARATUS USING THE OPTICAL SCANNING DEVICE HAVING A PLURALITY OF LIGHT SOURCES, AND COLOR IMAGE FORMING APPARATUS USING THE SAME

• US 20080123160A1
• Filed: 10/26/2007
• Published: 05/29/2008
• Est. Priority Date: 10/27/2006
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Omori, Atsufumi, Ishida, Masaaki, Tanabe, Jun, Nihei, Yasuhiro
• Granted Patent: US 8,089,665 B2
• Time in Patent Office: Days
• US Class Current: 358/475
• CPC Class Codes: B41J 2/473 using multiple light beams, wavelengths or colours
• CPC Class Codes: H04N 1/0402 Scanning different formats; Scanning with different densities of dots per unit length, e.g. different numbers of dots per inch (dpi); Conversion of scanning standards H04N1/00283 takes precedence; picture signal circuits for modification of image resolution H04N1/3935, H04N1/40068
• CPC Class Codes: H04N 1/0414 in the sub scanning direction
• CPC Class Codes: H04N 1/0458 using different portions of the scanning elements for different formats or densities of dots
• CPC Class Codes: H04N 1/1911 Simultaneously or substantially simultaneously scanning picture elements on more than one main scanning line, e.g. scanning in swaths
• CPC Class Codes: H04N 1/1916 using an array of elements displaced from one another in the main scan direction, e.g. a diagonally arranged array

Abstract

An optical scanning device includes n-odd (n≧2) light sources disposed at different positions at least in a sub-scanning direction, a pixel forming part in which one pixel is depicted by light beams emitted from m-odd (n≧m≧2) light sources of the n-odd light sources and a distance of adjacent light sources for emitting the light beams in the sub-scanning direction is less than 5 μm, and a light source driving control part configured to control an emitting state of the light sources for depicting the one pixel and conduct an emission driving control for moving a gravity center of the one pixel in the sub-scanning direction.

Claims

1. An optical scanning device, comprising:

n-odd (n≧

2) light sources disposed at different positions at least in a sub-scanning direction;

a pixel forming part in which one pixel is depicted by light beams emitted from m-odd (n≧

m≧

2) light sources of the n-odd light sources, and a distance of adjacent light sources for emitting the light beams in the sub-scanning direction is less than 5 μ

m; and

a light source driving control part configured to control an emitting state of the light sources for depicting the one pixel and conduct an emission driving control for moving a gravity center of the one pixel in the sub-scanning direction.

2. The optical scanning device according to claim 1, further comprising a sub-scanning direction pixel position detecting part configured to detect a deviation in position of the one pixel in the sub-scanning direction, wherein the light source driving control part conducts the emission driving control according to a detection result of the sub-scanning direction pixel position detection part.

3. The optical scanning device according to claim 1, wherein the light source driving control part controls an emitting time ratio of the light sources such that a total emitting time or a total exposure area of the light sources for depicting the one pixel becomes constant.

4. The optical scanning device according to claim 2, wherein the light source driving control part controls an emitting time ratio of the light sources such that a total emitting time or a total exposure area of the light sources for depicting the one pixel becomes constant.

5. The optical scanning device according to claim 1, wherein the light source driving control part controls an emitting level ratio of the light sources such that a total exposure energy of the light sources for depicting the one pixel becomes constant.

6. The optical scanning device according to claim 2, wherein the light source driving control part controls an emitting level ratio of the light sources such that a total exposure energy of the light sources for depicting the one pixel becomes constant.

7. The optical scanning device according to claim 1, wherein after start of the emission driving control, the one pixel is depicted by the light beams emitted from (m+1)-odd light sources, and after end of the emission driving control, the one pixel is depicted by m-odd light sources shifted at one light source in the sub-scanning direction relative to the m-odd light sources for depicting the one pixel before the emission driving control.

8. The optical scanning device according to claim 1, wherein after start of the emission driving control, the one pixel is depicted by the light beams emitted from (m+1)-odd light sources.

9. The optical scanning device according to claim 7, wherein the light source driving control part conducts a smoothing processing for stepwisely changing the emitting state of at least one of a light source positioned in an upper end and a light source positioned in a lower end in the sub-scanning direction in the light sources for depicting the one pixel by using at least one of a pulse width modulation (PWM) and a power modulation (PM), and smoothly moves the gravity center of the one pixel in the sub-scanning direction.

10. The optical scanning device according to claim 8, wherein the light source driving control part conducts a smoothing processing for stepwisely changing the emitting state of at least one of a light source positioned in an upper end and a light source positioned in a lower end in the sub-scanning direction in the light sources for depicting the one pixel by using at least one of a pulse width modulation (PWM) and a power modulation (PM), and smoothly moves the gravity center of the one pixel in the sub-scanning direction.

11. The optical scanning device according to claim 1, wherein the m-odd light sources simultaneously depict L-odd pixels arranged in L-groups (L≧

2) in the sub-scanning direction.

13. The optical scanning device according to claim 1, wherein a surface-emitting laser is used in the light source.

14. An image forming apparatus comprising the optical scanning device set forth in claim 1.

15. A color image forming apparatus comprising the optical scanning device set forth in claim 1.

12. An image forming apparatus, comprising:

n-odd (n≧

2) light sources disposed at different positions at least in a sub-scanning direction, wherein

one pixel is depicted by light beams emitted from m-odd (n≧

m≧

2) light sources of the n-odd light sources and a distance of adjacent light sources for emitting the light beams in the sub-scanning direction is less than 5 μ

m.

16. An optical scanning method, comprising the steps of:

preparing n-odd (n≧

2) light sources disposed at different positions at least in a sub-scanning direction;

depicting one pixel by light beams emitted from m-odd (n≧

m≧

2) light sources of the n-odd light sources;

setting a distance of adjacent light sources for emitting the light beams in the sub-scanning direction to be less than 5 μ

m;

controlling an emitting state of the light sources for depicting the one pixel; and

conducting an emission driving control for moving a gravity center of the one pixel in the sub-scanning direction.

17. The optical scanning method according to claim 16, further comprising the steps of:

detecting a deviation in position of the one pixel in the sub-scanning direction; and

performing the emission driving control according to a detection result.

18. The optical scanning method according to claim 16, wherein after start of the emission driving control, the one pixel is depicted by light beams emitted from (m+1)-odd light sources, and after end of the emission driving control, the one pixel is depicted by m-odd light sources shifted at one light source in the sub-scanning direction relative to the m-odd light sources for depicting the one pixel before the emission driving control.

19. The optical scanning method according to claim 16, wherein after start of the emission driving control, the one pixel is depicted by the light beams emitted from (m+1)-odd light sources.