Method and apparatus for forming images, and method for producing printed products

• US 8,982,422 B2
• Filed: 05/05/2014
• Issued: 03/17/2015
• Est. Priority Date: 05/10/2013
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Iwata, Muneaki, Ishida, Masaaki, Omori, Atsufumi, Fujita, Hayato
• Primary Examiner(s): TRAN, DUNG D
• Application Number:
  US14/269,332
• Publication Number:
  US 20140333941A1
• Time in Patent Office: 316 Days
• US Class Current: 358/3.27
• CPC Class Codes: G03G 15/04027 and forming half-tone image
• CPC Class Codes: H04N 1/40037 the reproducing element being a laser
• CPC Class Codes: H04N 1/4058 with details for producing a halftone screen at an oblique angle H04N1/4056 takes precedence
• CPC Class Codes: H04N 1/4092 Edge or detail enhancement

Abstract

An image forming apparatus for forming an image in accordance with light to be emitted from a light source includes: a digital half-toning unit configured to convert a uniform-pixel-value region of image data to a parallel-line pattern formed with a plurality of parallel lines extending obliquely with respect to a direction, in which pixels are arrayed, thereby expressing each gray level of the image data as an area percentage; a modulated-signal generating unit configured to generate a modulated signal by modulating the converted image data with a clock signal; a light-source driving unit configured to drive the light source according to the modulated signal; and an edge control unit configured to narrow a to-be-illuminated region, which is to be illuminated by the light from the light source, in each of edge neighborhoods of the lines constituting the parallel-line pattern, while increasing intensity of the light.

Claims

1. An image forming apparatus for forming an image in accordance with light caused to be emitted from a light source, the image forming apparatus comprising:

a digital half-toning unit configured to convert a uniform-pixel-value region formed with pixels having a same pixel value of image data to a parallel-line pattern formed with a plurality of parallel lines extending obliquely with respect to a direction, in which pixels are arrayed, thereby expressing each gray level of the image data as an area percentage;

a modulated-signal generating unit configured to generate a modulated signal by modulating the image data, in which each gray level is expressed as an area percentage, with a clock signal;

a light-source driving unit configured to drive the light source according to the modulated signal; and

an edge control unit configured to narrow a to-be-illuminated region, the to-be-illuminated region being to be illuminated by light to be emitted from the light source, in each of edge neighborhoods of the plurality of lines constituting the parallel-line pattern while increasing intensity of the light to be emitted from the light source.

2. The image forming apparatus according to claim 1, wherein the digital half-toning unit converts the uniform-pixel-value region to a parallel-line pattern formed with a plurality of lines of which area percentage depends on the pixel value.

3. The image forming apparatus according to claim 1, wherein the edge control unit narrows the to-be-illuminated region and increases the light intensity in a manner of causing the light source to emit same luminous energy as luminous energy to be emitted when the edge control unit controls none of the to-be-illuminated region and the light intensity.

4. The image forming apparatus according to claim 1, wherein the edge control unit narrows the to-be-illuminated region from an outer side toward a center of the line.

5. The image forming apparatus according to claim 1, wherein the edge control unit narrows the to-be-illuminated region by setting a light-on period of pixels belonging to the edge neighborhood shorter than a light-on period of pixels belonging to other region.

6. The image forming apparatus according to claim 1, further comprising a resolution converting unit, wherein

the digital half-toning unit outputs image data of a first resolution, and

the resolution converting unit converts the image data of the first resolution into image data of a second resolution, the second resolution being higher than the first resolution.

7. The image forming apparatus according to claim 6, further comprising:

a line-region detecting unit configured to detect the parallel line pattern from the image data of the first resolution; and

an edge detecting unit configured to detect the edge neighborhood of each of the plurality of lines constituting the parallel line pattern by pattern matching.

8. The image forming apparatus according to claim 7, wherein the line-region detecting unit obtains, for each region of the image data of the first resolution, object information specifying a type of an object represented by pixels in the region, and detects the parallel-line pattern based on the obtained object information.

9. The image forming apparatus according to claim 1, wherein when number of the plurality of lines per unit length or density of the plurality of lines is smaller than a preset value, the edge control unit stops changing the to-be-illuminated region and the light intensity in the edge neighborhood.

10. The image forming apparatus according to claim 1, wherein the light source is a vertical-cavity surface-emitting laser.

11. An image forming method for forming an image in accordance with light emitted from a light source, the image forming method comprising:

performing digital half-toning by converting a uniform-pixel-value region of image data to a parallel-line pattern formed with a plurality of parallel lines extending obliquely with respect to a direction, in which pixels are arrayed, thereby expressing each gray level of the image data as an area percentage;

performing edge control by narrowing a to-be-illuminated region, the to-be-illuminated region being to be illuminated by light to be emitted from the light source, in each of edge neighborhoods of the plurality of lines constituting the parallel-line pattern while increasing intensity of the light to be emitted from the light source;

generating a modulated signal by modulating the image data, in which each gray level is expressed as an area percentage, with a clock signal; and

driving the light source according to the modulated signal.

12. A method for producing a printed product, the method comprising:

performing digital half-toning by converting a uniform-pixel-value region of image data to a parallel-line pattern formed with a plurality of parallel lines extending obliquely with respect to a direction, in which pixels are arrayed, thereby expressing each gray level of the image data as an area percentage;

performing edge control by narrowing a to-be-illuminated region, the to-be-illuminated region being to be illuminated by light to be emitted from a light source, in each of edge neighborhoods of the plurality of lines constituting the parallel-line pattern while increasing intensity of the light to be emitted from the light source;

generating a modulated signal by modulating the image data, in which each gray level is expressed as an area percentage and of which number of gray levels is reduced, with a clock signal;

forming an electrostatic latent image on a latent-image carrier with light from the light source by driving the light source according to the modulated signal;

causing toner to stick to the electrostatic latent image formed on the latent-image carrier; and

transferring the toner onto a medium, thereby producing a printed product.