Image pickup apparatus for focusing an object image based on mirror reflected height of the object

• US 5,416,609 A
• Filed: 05/06/1993
• Issued: 05/16/1995
• Est. Priority Date: 05/13/1992
• Status: Expired due to Term

• Current Assignee: Minolta Camera Kabushiki Kaisha
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Fujii, Shinichi, Matsuda, Shinya
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): LEE, CHEUKFAN
• Application Number:
  US08/058,574
• Time in Patent Office: 740 Days
• Field of Search: 358/474, 358/471, 358/497, 358/486, 358/406, 358/909, 358/493, 250/560, 250/261.7, 250/201.6, 250/208.1, 377/8, 355/309, 355/308, 271/55, 271/60, 271/3.1, 73/1 J, 209/939, 33/707, 33/547
• US Class Current: 358/474
• CPC Class Codes: H04N 1/1013 with sub-scanning by translatory movement of at least a part of the main-scanning components H04N1/107 takes precedence
• CPC Class Codes: H04N 1/1043 of a sensor array
• CPC Class Codes: H04N 1/193 using electrically scanned linear arrays , e.g. linear CCD arrays
• CPC Class Codes: H04N 2201/0434 specially adapted for scanning pages of a book
• CPC Class Codes: H04N 2201/0436 Scanning a picture-bearing surface lying face up on a support H04N2201/0434 takes precedence; using cylindrical picture bearing surfaces H04N1/06; with manual scanning H04N1/107

Abstract

An image pickup apparatus for reading an object having a curved document surface such as an opened book, constructed to focus an optical system all the object. A line sensor is moved for scanning the object, thereby a distance between the line sensor and the object is measured, and the object is imaged while controlling an optical system based on data of measured distance so that an object image is in focus on the line sensor. This allows all over the object surface to be in focus, whereby the clear image without blur is obtainable.

Claims

1. An image pickup apparatus comprising:

a sensor;

a table on which an object is placed;

an optical system for forming an object image on the sensor, wherein the object image concerns only a top view of the object

a mirror member disposed on the side of the object;

measuring means for measuring a height of the object based on a side view image of the object reflected in the mirror member; and

focusing means for focusing the optical system based on a measurement result by the measuring means so that the top view image is in focus on the sensor.

2. An image pickup apparatus as claimed in claim 1, wherein the optical system varies a focal length.

3. An image pickup apparatus as claimed in claim 2, further comprising rectifying means for rectifying image data outputted from the sensor with digital variable magnification.

4. An image pickup apparatus as claimed in claim 3, wherein the rectifying means rectifies the image data based on the variation of the focal length.

5. An image pickup apparatus as claimed in claim 3, wherein the rectifying means rectifies the image data based on the variation of the focal length and distance from the sensor to the object.

6. An image pickup apparatus as claimed in claim 1, wherein the distance from the sensor to the table is constant.

7. An image pickup apparatus as claimed in claim 1, wherein the optical system includes a zoom lens.

8. An image pickup apparatus comprising:

a sensor;

an optical system for forming a top view image of an object on the sensor;

taking means for taking an object edge information from an object image projected to a side direction;

measuring means for measuring a height of the object based on the object edge information; and

focusing means for focusing of the top view image based on the measuring result which is the object edge information.

9. An image pickup apparatus as claimed in claim 8, wherein the optical system varies a focal length.

10. An image pickup apparatus as claimed in claim 9, further comprising rectifying means for rectifying image date outputted from the sensor with digital variable magnification.

11. An image pickup apparatus as claimed in claim 10, wherein the rectifying means rectifies the image data based on the variation of the focal length.

12. An image pickup apparatus as claimed in claim 10, wherein the rectifying means rectifies the image data based on the variation of the focal length and distance from the sensor to the object.

13. An image pickup apparatus as claimed in claim 8, wherein the optical system includes a zoom lens.

14. An image pickup apparatus as claimed in claim 8, further comprising rectifying means for rectifying image data outputted from the sensor with digital variable magnification.

15. An image pickup apparatus comprising;

a line sensor;

an optical system for forming an object image on the line sensor;

scanning means for scanning the object by moving the line sensor relatively to the object;

distance measuring means for measuring a distance to the object at plural points along a scanning direction of the scanning means by judging a position on the line sensor on which an image of the object edge is formed based on the difference in brightness between the object image and a background image thereof formed on the line sensor; and

focusing means for focusing the optical system based on the measurement result of the distance measuring means so that the object image is in focus on the line sensor.

16. An image pickup apparatus for enabling a reproduction of an image of an object on a curved surface, such as an open book, comprising:

a line sensor having a plurality of photoelectric conversion devices disposed linearly;

a support surface on which the object is placed;

an optical system for forming an image of the object placed on the support surface to the line sensor;

scanning means for scanning the object by moving the line sensor relative to the object;

measuring means for measuring a height of the object placed on the support surface at plural points along a scanning direction of the scanning means by judging a position on the line sensor on which an image of the object edge is formed based on a difference in brightness between the object image and the support surface image formed on the line sensor; and

control means, effective for changing a relative positional relationship among the line sensor, the optical system and the object based on the measurement result of the measuring means so that the object image is in focus on the line sensor during scanning by the scanning means.