Image input device with dust detector

• US 6,792,161 B1
• Filed: 07/29/1999
• Issued: 09/14/2004
• Est. Priority Date: 07/31/1998
• Status: Expired due to Fees

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Imaizumi, Shoji, Hashimoto, Keisuke
• Primary Examiner(s): Williams, Kimberly A.
• Assistant Examiner(s): VIDA, MELANIE M
• Application Number:
  US09/363,055
• Time in Patent Office: 1,874 Days
• Field of Search: 382/275, 382/254, 358/463, 358/474, 358/497, 358/483, 358/3.26, 356/237.1, 356/239.1, 356/239.2, 356/239.3, 356/124, 356/237.2, 356/237.5, 356/954, 359/216
• US Class Current: 382/275
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/00013 Reading apparatus
• CPC Class Codes: H04N 1/00029 Diagnosis, i.e. identifying a problem by comparison with a normal state
• CPC Class Codes: H04N 1/00037 Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/0005 in service, i.e. during normal operation
• CPC Class Codes: H04N 1/00058 using a separate apparatus
• CPC Class Codes: H04N 1/00063 using at least a part of the apparatus itself, e.g. self-testing
• CPC Class Codes: H04N 1/4097 Removing errors due external factors, e.g. dust, scratches

Abstract

An image input device identifies what part of the optical input system needs cleaning when there is dust or other foreign matter in the optical input system. This image input device has an image noise position detector for capturing image data from a scanner, and detecting the main scanning address of noise information corresponding to image noise present in the image data; a focus calculator for calculating focus information around the main scanning address detected by the image noise position detector; focus information storage for storing focus information for each subscanning line; and a foreign matter position determining circuit for determining the location of foreign matter on the scanner based on the focus information stored in the focus information storage.

Claims

1. An image input device comprising:

an optical system projecting an image to be captured;

a sensor capturing the image projected thereon by the optical system and disposed in an optical path of the optical system, said sensor comprising a plurality of picture elements;

a first controller detecting noise in an image signal outputted from the sensor and identifying one of the picture elements of the sensor corresponding to the noise; and

a second controller identifying in the optical path a location of a substance causing the noise detected by the first controller.

2. The image input device as set forth in claim 1, wherein the second controller detects focus information of the projected image at the picture element identified by the first controller, and identifies the location of the substance based on the focus information.

3. The image input device as set forth in claim 2, wherein the focus information relates to a difference between an image signal level of the picture element and the image signal level of a picture element located around the picture element.

4. The image input device as set forth in claim 1, further comprising an indication device indicating the position identified by the second controller.

5. The image input device as set forth in claim 1, further comprising a computation device removing the noise from the image signal.

6. An image input device comprising:

a sensor having a plurality of picture elements arranged in a main scanning direction;

an optical system for projecting onto the sensor an image to be scanned,

said optical system moving in a subscanning direction orthogonal to the main scanning direction to sequentially project the image onto the picture elements of the sensor, and

comprising a plurality of optical elements configured so that a distance between the optical elements changes as the optical system moves in the subscanning direction;

a first controller detecting noise in an image signal outputted from the sensor and identifying a picture element of the sensor corresponding to the noise; and

a second controller identifying one of the optical elements which has a substance causing the noise based on a change in image signal outputted from the identified picture element when the optical system moves in the subscanning direction.

7. The image input device as set forth in claim 6, wherein the optical elements include a mirror that moves in conjunction with a subscanning operation and a lens that is stationary during the subscanning operation, and

the second controller determines that the substance is present on the mirror when a change in the noise is large, and determines that the substance is present on the lens when the change is small.

8. The image input device as set forth in claim 6, further comprising an indication device indicating the optical element identified by the second controller.

9. The image input device as set forth in claim 6, further comprising a computation device removing the noise.

10. A detection method for detecting a location of a substance disposed in an optical system, said method comprising:

projecting an optical image onto a sensor by the optical system;

capturing the projected optical image by the sensor;

detecting noise due to the substance in an output signal from the sensor based on the captured optical image;

identifying one of picture elements of the sensor corresponding to the noise; and

determining a location in an optical path of the optical system of the substance causing the noise.

11. The detection method as set forth in claim 10, wherein the determining comprises detecting focus information of the projected optical image at the identified picture element, and identifying the location of the substance in the optical path based on the focus information.

12. The detection method as set forth in claim 11, wherein the optical system comprises a plurality of optical elements configured to move relative to each other in the projecting;

the capturing is repeated a plurality of times while the optical elements are moving; and

the determining comprises identifying one of the optical that has the substance causing the noise based on a change in the noise while the optical elements are moving.

13. The detection method as set forth in claim 12, wherein the optical elements include a mirror that moves and a lens that is stationary, and

the determining further comprises determining that the substance is present on the mirror when the change in the noise is large, and determining that the substance is present on the lens when the change in the noise is small.

14. A detection method for detecting a location of disposed in an image input device, said method comprising:

projecting an optical image onto a sensor by an optical system through an intervening glass for holding an original document;

capturing the projected optical image by the sensor;

detecting noise due to the substance in an output signal from the sensor based on the captured optical image;

identifying one of picture elements of the sensor corresponding to the noise; and

determining a location in an optical path of the optical system of the substance causing the noise.

15. The detection method as set forth in claim 14, wherein the determining comprises:

detecting focus information of the projected optical image at the identified picture element,

detecting the number of the picture elements of the sensor identified as corresponding to the noise when the detected focus information indicates a good focus, and

determining that the substance is on the sensor when the detected number is large, and determining that the substance is on the intervening glass when the detected number is small.

16. The detection method as set forth in claim 15, wherein the optical system comprises a plurality of optical elements configured to move relative manner relative to each other in the projecting;

the capturing is repeated a plurality of times while the optical elements are moving; and

the determining comprises identifying one of the optical elements that has the substance causing the noise based on a change in the noise while the optical elements are moving when the focus information does not indicate the good focus.

17. The detection method as set forth in claim 16, wherein the optical elements include a mirror that moves and a lens that is stationary, and

the optical element identifying comprises determining that the substance is present on the mirror when the change in the nose is large, and determining that the substrate is present on the lens when the change in the noise is small.