Image read apparatus

• US 20050157319A1
• Filed: 09/14/2004
• Published: 07/21/2005
• Est. Priority Date: 01/21/2004
• Status: Active Grant

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Onishi, Ayumi, Saito, Masato, Matsubara, Yoshitake, Mizuhashi, Satoshi, Mizuta, Yasuhisa, Furuoya, Sadao, Sodeura, Minoru
• Granted Patent: US 7,626,735 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: H04N 1/12 using the sheet-feed movement or the medium-advance or the drum-rotation movement as the slow scanning component, e.g. arrangements for the main-scanningsheet-feed movement by translatory movement of a flat picture-bearing surface H04N1/1008; main-scanning using oscillating or rotating mirrors H04N1/113; using multi-element arrays H04N1/19
• CPC Class Codes: H04N 1/192 Simultaneously or substantially simultaneously scanning picture elements on one main scanning line
• CPC Class Codes: H04N 1/2034 at identical corresponding positions, i.e. without time delay between the two image signals
• CPC Class Codes: H04N 1/207 Simultaneous scanning of the original picture and the reproduced picture with a common scanning device
• CPC Class Codes: H04N 1/4095 Correction of errors due to scanning a two-sided document, i.e. show-through correction

Abstract

The invention provides an image reading apparatus includes a feeder that feeds a sheet, a transfer path on which the sheet fed by the feeder is transferred, a first reading unit that captures a first image on a first face of the sheet from one side of the transfer path to obtain first image data, a second reading unit that captures a second image on a second face of the sheet from the other side of the transfer path to obtain second image data, and a correction unit that substantially equalizes image density of the first image data and that of the second image data in a case where the first image and the second image are captured at a single transfer of the sheet through the transfer path.

Claims

1. An image reading apparatus comprising:

a feeder that feeds a sheet;

a transfer path on which the sheet fed by the feeder is transferred;

a first reading unit that captures a first image on a first face of the sheet from one side of the transfer path to obtain first image data;

a second reading unit that captures a second image on a second face of the sheet from the other side of the transfer path to obtain second image data; and

a correction unit that substantially equalizes image density of the first image data and that of the second image data in a case where the first image and the second image are captured at a single transfer of the sheet through the transfer path.

2. The image reading apparatus according to claim 1, wherein

the first reading unit comprises a color sensor for capturing the first image as color image data and a first monochrome sensor for capturing the first image as monochrome image data,

the second reading unit comprises a second monochrome sensor for capturing the second image as second monochrome image data, and

the correction unit corrects the first monochrome image data based on the color image data so as to substantially equalize the image density of the first monochrome image data and that of the second monochrome image data.

3. The image reading apparatus according to claim 1, wherein

the first reading unit comprises a first color sensor for capturing the first image as first color image data and a first monochrome sensor for capturing the first image as first monochrome image data,

the second reading unit comprises a second color sensor for capturing the second image as second color image data and a second monochrome sensor for capturing the second image as second monochrome image data, and

the correction unit corrects the second monochrome image data based on the second color image data so as to substantially equalize the image density of the first monochrome image data and that of the second monochrome image data.

4. The image reading apparatus according to claim 3, wherein the correction unit corrects the first monochrome image data based on the first color image data.

5. The image reading apparatus according to claim 3, wherein the second color sensor has lower resolution than the first color sensor.

18. The image reading apparatus according to claim 1, wherein the correction unit corrects one of the first image data and the second image data so that the image density of the one is in a range of 93% of that of the other to 107% of that of the other.

19. The image reading apparatus according to claim 2, wherein the correction unit corrects the first monochrome image data so that the image density of the first monochrome image data is in a range of 93% of that of the second monochrome image data to 107% of that of the second monochrome image data.

20. The image reading apparatus according to claim 3, wherein the correction unit corrects the second monochrome image data so that the image density of the second monochrome image data is in a range of 93% of that of the first monochrome image data to 107% of that of the first monochrome image data.

6. An image reading apparatus comprising:

a transfer path on which a sheet is transferred;

a first reading unit that captures a first image on a first face of the sheet to obtain first image data, the first reading unit including a first light source for emitting light to the first face of the sheet from one side of the transfer path and a first sensor for receiving a reflected light from the first face of the sheet;

a second reading unit that captures a second image on a second face of the sheet to obtain second image data, the second reading unit including a second light source for emitting light to the second face of the sheet from the other side of the transfer path and a second sensor for receiving a reflected light from the second face of the sheet; and

a correction unit that corrects the first image data so as to substantially equalize image density of the first image data and that of the second image data in a case where the first image and the second image are captured at a single transfer of the sheet through the transfer path, wherein

the second light source has a wider emission wavelength range than the first light source.

7. The image reading apparatus according to claim 6, wherein

the first light source is a xenon lamp, and

the second light source is an LED.

8. The image reading apparatus according to claim 6, wherein

the first sensor is a first image sensor for capturing the reflected light through a minification optical system, and

the second sensor is a second image sensor for capturing the reflected light at a closer position than the first sensor.

21. The image reading apparatus according to claim 6, wherein the correction unit corrects the first image data so that the image density of the first image data is in a range of 93% of that of the second image data to 107% of that of the second image data.

9. An image reading apparatus comprising:

a first reading unit that captures a first face of a sheet from one side of the sheet to obtain at least one of first color image data and first monochrome image data;

a second reading unit that captures a second face of the sheet from the other side of the sheet to obtain monochrome image data; and

a correction unit that corrects the first monochrome image data based on the first color image data in a case where the first face and the second face of the sheet are captured by the first reading unit and the second reading unit in a monochrome mode.

10. The image reading apparatus according to claim 9, wherein the correction unit corrects the first monochrome image data so as to substantially equalize image density of the first monochrome image data and that of the second monochrome image data.

11. The image reading apparatus according to claim 9, further comprising:

a generating unit that generates a correction value, which is used for equalizing the image density of the first monochrome image data and that of the second monochrome image data, based on the first color image data, wherein

the correction unit corrects the first monochrome image data with the correction value.

12. The image reading apparatus according to claim 9, further comprising:

an inversion unit that inverts the sheet after the first face of the sheet is captured by the first reading unit and transfers the sheet to the first reading unit.

22. The image reading apparatus according to claim 10, wherein the correction unit corrects the first monochrome image data so that the image density of the first monochrome image data is in a range of 93% of that of the second monochrome image data to 107% of that of the second monochrome image data.

23. The image reading apparatus according to claim 11, wherein the correction unit corrects the first monochrome image data so that the image density of the first monochrome image data is in a range of 93% of that of the second monochrome image data to 107% of that of the second monochrome image data.

13. An image reading apparatus comprising:

a feeder that feeds a sheet;

a transfer path on which the sheet fed by the feeder is transferred;

a first reading unit that captures a first image on a first face of the sheet from one side of the transfer path to obtain first image data;

a second reading unit that captures a second image on a second face of the sheet from the other side of the transfer path to obtain second image data; and

an acceptor that accepts a selection concerning either (a) to bring image density of the second image data close to that of the first image data, or (b) to bring the image density of the first image data close to that of the second image data, in a case where the first image and the second image are captured at a single pass transfer of the sheet through the transfer path.

14. The image reading apparatus according to claim 13, wherein

the first reading unit captures the first image to obtain at least one of color image data and monochrome image data, and

the second reading unit captures the second image to obtain monochrome image data.

15. The image reading apparatus according to claim 13, wherein the first reading unit and the second reading unit have light sources for emitting light to the sheet, respectively, each having a different emission characteristic.

16. The image reading apparatus according to claim 13, wherein the first reading unit and the second reading unit have sensors for capturing the image on the sheet, respectively, each having a different detection characteristic.

17. The image reading apparatus according to claim 13, wherein the acceptor accepts a selection concerning either (a) to prioritize sharpness of the image, or (b) to prioritize reproducibility of the image density.