IMAGE READING DEVICE, IMAGE FORMING APPARATUS, AND IMAGE READING METHOD

• US 20150002908A1
• Filed: 06/25/2014
• Published: 01/01/2015
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: KYOCERA Document Solutions, Inc. (Kyocera Corporation)
• Original Assignee: KYOCERA Document Solutions, Inc. (Kyocera Corporation)
• Inventors: Fujita, Hiroyuki
• Granted Patent: US 8,928,946 B1
• Time in Patent Office: Days
• US Class Current: 358/3.26
• CPC Class Codes: H04N 1/00801 according to characteristics of the original
• CPC Class Codes: H04N 1/38 Circuits or arrangements for blanking or otherwise eliminating unwanted parts of pictures H04N1/387 takes precedence
• CPC Class Codes: H04N 1/56 Processing of colour picture signals H04N1/52 takes precedence

Abstract

A cover member is openable and closable with respect to a document table, and has a color reference surface facing the document table, and a partial region provided on a color reference surface and having a predetermined density different from a density of the color reference surface. When a document determination portion determines that a document is a book document, a density correction portion corrects a density in a specific density correction range at a central portion in document image data read from a document by a image reading portion, based on a second density difference which is a density difference between a density of the color reference surface read by a reading control portion when a book document is placed on a document placement surface, and a density of the color reference surface read by the image reading portion when the cover member is closed.

Claims

1. An image reading device comprising:

a document table having a document placement surface which allows a document to be placed thereon;

an image reading portion configured to, based on light reflected when light is radiated through the document placement surface to a document placed on the document placement surface, read image data from the document;

a cover member configured to be openable and closable with respect to the document table, and having a color reference surface facing the document table and a partial region provided on the color reference surface, the partial region having a predetermined density different from a density of the color reference surface;

a reading control portion configured to read image data from the color reference surface and the partial region of the cover member by the image reading portion;

a document determination portion configured to, when a first density difference which is a density difference between a density of the color reference surface and a density of the partial region in color reference image data read by the reading control portion is equal to or smaller than a predetermined first threshold value, determine that the document placed on the document placement surface is a book document; and

a density correction portion configured to, when the document determination portion determines that the document is a book document, correct a density in a specific density correction range at a central portion in document image data read from the document by the image reading portion, based on a second density difference which is a density difference between a density of the color reference surface read by the reading control portion when the book document is placed on the document placement surface, and a density of the color reference surface read by the image reading portion when the cover member is closed.

2. The image reading device according to claim 1, wherein when the first density difference is equal to or smaller than the first threshold value and a predetermined belt-like image appears in the document image data, the document determination portion determines that the document placed on the document placement surface is a book document.

3. The image reading device according to claim 1, wherein the density correction portion corrects only image data whose density is equal to or smaller than a predetermined second threshold value, in the density correction range in the document image data.

4. The image reading device according to claim 3, wherein in determination of whether to correct image data, the density correction portion decreases the second threshold value as the distance from a center of the density correction range increases.

5. The image reading device according to claim 1, wherein the density correction portion decreases a correction amount for density in the density correction range as the distance from a center of the density correction range increases.

6. The image reading device according to claim 5, wherein the density correction portion corrects the document image data in accordance with the following expression (1) or (11), where, using the center of the density correction range as an origin, a line number at each correction target position is n, image data at the line number n before correction is Y(n), image data at the line number n after correction is Y(n′

), the second density difference is A, and the total number of lines included in the density correction range is N.

Y(n′

)=Y(n)−

A×

(N−

|n|)/N 

 

(1)

Y(n′

)=Y(n)+A×

(N−

|n|)/N 

 

(11)

7. The image reading device according to claim 1, wherein the density correction portion changes the density correction range, based on the first density difference or the second density difference.

8. The image reading device according to claim 1, further comprising a document conveying portion configured to convey a document so as to pass through a reading position where the image reading portion reads image data, the document conveying portion also serving as the cover member, wherein

the document table has a conveyance reading surface which allows transmission of light radiated from the image reading portion to the document conveyed by the document conveying portion, and

the color reference surface and the partial region are provided so as to face the conveyance reading surface.

9. The image reading device according to claim 1, further comprising a storage portion storing in advance a density of the color reference surface read by the image reading portion when the book document is not placed on the document placement surface and the cover member is closed, wherein

the second density difference is a density difference between the density of the color reference surface read by the reading control portion when the book document is placed on the document placement surface, and the density of the color reference surface which has been read by the image reading portion when the book document is not placed on the document placement surface and the cover member is closed, and which is stored in the storage portion.

10. The image reading device according to claim 9, further comprising:

a book document detection portion configured to detect whether or not the book document is placed on the document placement surface; and

a control portion configured to store, into the storage portion, a density of the color reference surface read by the image reading portion when the book document detection portion has detected that the book document is not placed on the document placement surface, and the cover member is closed.

11. An image forming apparatus comprising:

the image reading device according to claim 1; and

an image forming portion configured to form an image based on image data read by the image reading device.

12. The image reading device according to claim 1, further comprising:

a height estimation portion configured to estimate the height of lifting at a central portion of the document, based on the second density difference which is the density difference between the density of the color reference surface read by the reading control portion and the density of the color reference surface read by the image reading portion when the cover member is closed; and

an enlargement correction portion configured to, when the document determination portion determines that the document is a book document, enlarge an image in a specific enlargement correction range at the central portion of the document image data read from the document by the image reading portion, with an enlargement factor based on the height estimated by the height estimation portion.

13. The image reading device according to claim 12, wherein the enlargement correction portion includes:

a difference acquiring portion configured to acquire a difference between the length of spread pages of the document and the length of a target to be read by the image reading portion on the spread pages of the document placed on the document placement surface; and

an enlargement factor setting portion configured to set the enlargement factor, based on the height estimated by the height estimation portion and the difference acquired by the difference acquiring portion.

14. The image reading device according to claim 12, wherein the enlargement correction portion changes the enlargement factor for the image in the enlargement correction range such that the closer to a center of the enlargement correction range, the greater the enlargement factor is.

15. The image reading device according to claim 12, wherein the enlargement correction portion sets the enlargement correction range, based on the second density difference.

16. An image forming apparatus comprising:

the image reading device according to claim 12; and

an image forming portion configured to form an image based on image data read by the image reading device.

17. An image reading method executed by an image reading device that includes:

a document table having a document placement surface which allows a document to be placed thereon;

an image reading portion configured to, based on light reflected when light is radiated through the document placement surface to a document placed on the document placement surface, read image data from the document; and

a cover member configured to be openable and closable with respect to the document table, and having a color reference surface facing the document table and a partial region provided on the color reference surface, the partial region having a predetermined density different from a density of the color reference surface, the image reading method comprising;

a reading control step of reading image data from the color reference surface and the partial region of the cover member by the image reading portion;

a document determination step of, when a first density difference which is a density difference between a density of the color reference surface and a density of the partial region in color reference image data read in the reading control step is equal to or smaller than a predetermined first threshold value, determining that the document placed on the document placement surface is a book document; and

a density correction step of, when it is determined in the document determination step that the document is a book document, correcting a density in a specific density correction range at a central portion in document image data read from the document by the image reading portion, based on a second density difference which is a density difference between a density of the color reference surface read in the reading control step when the book document is placed on the document placement surface, and a density of the color reference surface read by the image reading portion when the cover member is closed.

18. The image reading method according to claim 17, further comprising:

a height estimation step of estimating the height of lifting at a central portion of the document, based on the second density difference which is the density difference between the density of the color reference surface read in the reading control step and the density of the color reference surface read by the image reading portion when the cover member is closed; and

an enlargement correction step of, when it is determined in the document determination step that the document is a book document, enlarging an image in a specific enlargement correction range at the central portion of the document image data read from the document by the image reading portion, with an enlargement factor based on the height estimated in the height estimation step.