Line Head and an Image Forming Apparatus Using the Line Head

• US 20080024587A1
• Filed: 07/12/2007
• Published: 01/31/2008
• Est. Priority Date: 07/27/2006
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: NOMURA, Yujiro, KOIZUMI, Ryuta, IKUMA, Ken, INOUE, Nozomu
• Granted Patent: US 7,808,519 B2
• Time in Patent Office: Days
• US Class Current: 347/237
• CPC Class Codes: B41J 2/451 Special optical means therefor, e.g. lenses, mirrors, focusing means
• CPC Class Codes: G03G 15/04045 for exposing image information provided otherwise than by directly projecting the original image onto the photoconductive recording material, e.g. digital copiers G03G15/041, G03G15/043 take precedence
• CPC Class Codes: G03G 2215/0409 Light-emitting diodes, i.e. LED-array

Abstract

A line head, includes: a microlens array in which a plurality of microlenses having a magnification whose absolute value is below 1 are arranged in a main scanning direction of a surface-to-be-scanned, and a plurality of luminous element groups which are arranged in a one-to-one correspondence with the respective plurality of microlenses, wherein in each of the plurality of luminous element groups, a plurality of luminous elements are arranged at mutually different main-scanning-direction positions in the main scanning direction, the plurality of luminous elements are respectively caused to emit lights at timings in conformity with a movement of the surface-to-be-scanned in a sub scanning direction, and light beams emitted from the plurality of luminous elements are imaged on the surface-to-be-scanned at mutually different main-scanning-direction positions in the main scanning direction to form a plurality of spots side by side on the surface-to-be-scanned in the main scanning direction, and in each of the plurality of luminous element groups, out of the plurality of luminous elements constituting the luminous element group, two luminous elements caused to emit lights to form adjacent spots are arranged at mutually different sub-scanning-direction positions in the sub scanning direction.

Claims

1. A line head, comprising:

a microlens array in which a plurality of microlenses having a magnification whose absolute value is below 1 are arranged in a main scanning direction of a surface-to-be-scanned, and

a plurality of luminous element groups which are arranged in a one-to-one correspondence with the respective plurality of microlenses, wherein

in each of the plurality of luminous element groups, a plurality of luminous elements are arranged at mutually different main-scanning-direction positions in the main scanning direction,

the plurality of luminous elements are respectively caused to emit lights at timings in conformity with a movement of the surface-to-be-scanned in a sub scanning direction, and light beams emitted from the plurality of luminous elements are imaged on the surface-to-be-scanned at mutually different main-scanning-direction positions in the main scanning direction to form a plurality of spots side by side on the surface-to-be-scanned in the main scanning direction, and

in each of the plurality of luminous element groups, out of the plurality of luminous elements constituting the luminous element group, two luminous elements caused to emit lights to form adjacent spots are arranged at mutually different sub-scanning-direction positions in the sub scanning direction.

2. The line head of claim 1, wherein

in each of the plurality of luminous element groups, a plurality of luminous element lines, each of which is formed by arranging a plurality of luminous elements in line in the main scanning direction, are arranged in the sub scanning direction of the surface-to-be-scanned, and

in each of the plurality of luminous element lines, the plurality of luminous elements constituting the luminous element line are caused to emit lights at a timing in conformity with the movement of the surface-to-be-scanned in the sub scanning direction.

3. The line head of claim 2, wherein the plurality of luminous element lines are arranged in the sub scanning direction of the surface-to-be-scanned in each of the plurality of luminous element groups such that the plurality of luminous elements are mutually arranged in a staggered arrangement in the main scanning direction.

4. The line head of claim 1, wherein

the luminous element groups which are adjacent to each other in the main scanning direction partly overlap each other in the main scanning direction, and

in each luminous element group, out of the plurality of luminous elements constituting the luminous element group, a closest luminous element which is closest to the other luminous element group adjacent to the luminous element group in the main scanning direction is arranged at a sub-scanning-direction position different from a position of the other luminous element group in the sub scanning direction.

5. The line head of claim 1, further comprising:

a substrate on which the plurality of luminous elements are provided, and

a driving circuit which drives the plurality of luminous element groups, is provided on the substrate, and is electrically connected to the plurality of luminous elements via wiring.

6. The line head of claim 1, wherein a plurality of lens lines, each of which is formed by arranging the plurality of microlenses in line in the main scanning direction, are arranged in the sub scanning direction, whereby the plurality of microlenses are arranged in a staggered arrangement in the microlens array.

7. The line head of claim 6, wherein two luminous element groups which are arranged corresponding to the microlenses which are adjacent to each other in the sub scanning direction partly overlap in the main scanning direction.

8. A line head, comprising:

a microlens array in which a plurality of microlenses having a magnification whose absolute value is below 1 are arranged in a main scanning direction of a surface-to-be-scanned,

a plurality of luminous element groups which are arranged in a one-to-one correspondence with the respective plurality of microlenses, wherein

each of the plurality of luminous element groups includes a plurality of luminous elements which are arranged in a staggered arrangement,

the arranged positions of the luminous elements constituting each luminous element group in the main scanning direction differ from each other, and

the plurality of luminous elements are respectively caused to emit lights at timings in conformity with a movement of the surface-to-be-scanned in a sub scanning direction, and light beams emitted from the plurality of luminous elements are imaged on the surface-to-be-scanned at mutually different main-scanning-direction positions in the main scanning direction to form a plurality of spots side by side on the surface-to-be-scanned in the main scanning direction.

9. The line head of claim 8, wherein

a plurality of luminous element lines, each of which is formed by arranging a plurality of luminous elements in the main scanning direction, are arranged in the sub scanning direction of the surface-to-be-scanned, whereby the plurality of luminous elements which constitute the luminous element group are arranged in a staggered arrangement in each of the plurality of luminous element groups, and

the plurality of luminous elements which constitute the luminous element line are caused to emit lights at a timing in conformity with the movement of the surface-to-be-scanned in the sub scanning direction in each of the plurality of luminous element lines.

10. The line head of claim 9, wherein a plurality of lens lines, each of which is formed by arranging the plurality of microlenses in line in the main scanning direction, are arranged in the sub scanning direction, whereby the plurality of microlenses are arranged in a staggered arrangement in the microlens array.

11. The line head of claim 10, wherein two luminous element groups which are arranged corresponding to the microlenses which are adjacent to each other in the sub scanning direction partly overlap in the main scanning direction.

12. An image forming apparatus, comprising:

a latent image carrier whose surface is transported in a sub scanning direction,

a line head which images a plurality of spots on the surface of the latent image carrier in a main scanning direction substantially orthogonal to the sub scanning direction to form a latent image, and

a developing section which develops the latent image on the latent image carrier with toner, wherein

the line head includes;

a microlens array in which a plurality of microlenses having a magnification whose absolute value is below 1 are arranged in the main scanning direction, and

a plurality of luminous element groups which are arranged in a one-to-one correspondence with the respective plurality of microlenses, and wherein

in each of the plurality of luminous element groups, a plurality of luminous elements are arranged at mutually different main-scanning-direction positions in the main scanning direction,

the plurality of luminous elements are respectively caused to emit lights at timings in conformity with a transportation of the surface of the latent image carrier in the sub scanning direction, and light beams emitted from the plurality of luminous elements are imaged on the surface of the latent image carrier at mutually different main-scanning-direction positions in the main scanning direction to form a plurality of spots side by side on the surface of the latent image carrier in the main scanning direction, and

in each of the plurality of luminous element groups, out of the plurality of luminous elements constituting the luminous element group, two luminous elements caused to emit lights to form adjacent spots are arranged at mutually different sub-scanning-direction positions in the sub scanning direction.

13. An image forming apparatus, comprising:

a latent image carrier whose surface is transported in a sub scanning direction,

a line head which images a plurality of spots on the surface of the latent image carrier in a main scanning direction substantially orthogonal to the sub scanning direction to form a latent image, and

a developing section which develops the latent image on the latent image carrier with toner, wherein

the line head includes;

a microlens array in which a plurality of microlenses having a magnification whose absolute value is below 1 are arranged in the main scanning direction, and

a plurality of luminous element groups which are arranged in a one-to-one correspondence with the respective plurality of microlenses, and wherein

each of the plurality of luminous element groups has a plurality of luminous elements arranged in a staggered arrangement,

the arranged positions of the luminous elements constituting each luminous element group in the main scanning direction differ from each other, and

the plurality of luminous elements are respectively caused to emit lights at timings in conformity with a transportation of the surface of the latent image carrier in the sub scanning direction, and light beams emitted from the plurality of luminous elements are imaged on the surface of the latent image carrier at mutually different main-scanning-direction positions in the main scanning direction to form a plurality of spots side by side on the surface of the latent image carrier in the main scanning direction.