Image pickup apparatus including selective insertion of ND filter into taking lens optical path based on luminance of object to be imaged

• US 7,199,830 B1
• Filed: 11/10/1999
• Issued: 04/03/2007
• Est. Priority Date: 11/11/1998
• Status: Expired due to Fees

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Tanaka, Toshiyuki, Niikawa, Masahito
• Primary Examiner(s): Srivastava; Vivek
• Assistant Examiner(s): Hannett; James M.
• Application Number:
  US09/437,497
• Time in Patent Office: 2,701 Days
• Field of Search: 348/223.1, 348/224.1, 348/225.1, 348/229.1, 348/234, 348/363, 348/362, 348/235, 348/236, 359/227, 359/888, 359/889
• US Class Current: 348/362
• CPC Class Codes: G03B 2217/007 Details of energy supply or management
• CPC Class Codes: G03B 7/08 Control effected solely on the basis of the response, to the intensity of the light received by the camera, of a built-in light-sensitive device
• CPC Class Codes: G03B 7/18 in accordance with light-reducing "factor" of filter or other obturator used with or on the lens of the camera
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/632 for displaying or modifying preview images prior to image capturing, e.g. variety of image resolutions or capturing parameters
• CPC Class Codes: H04N 5/907 using static stores, e.g. storage tubes or semiconductor memories H04N5/91 takes precedence
• CPC Class Codes: H04N 9/804 involving pulse code modulation of the colour picture signal components

Abstract

In a digital camera using an ND filter to be inserted into an optical path of an optical lens system, defocus quantity of the taking lens and imbalance of white balance due to the insertion of the ND filter are previously calculated or measured. The ND filter is inserted into the optical path when user fully pushes down a shutter release switch for taking an image of an object in order to shorten supply of electric power to an actuator for driving the ND filter. The position of the taking lens is compensated just before an image pickup device is driven for taking the image. The white balance of the image signals from the image pickup device is compensated by using the previously measured compensation coefficients.

Claims

1. An image pickup apparatus comprising:

an optical lens system;

a luminance sensor for sensing a luminance of an object;

a judging device for judging whether the luminance of the object is higher than a predetermined value or not;

a neutral density filter to be inserted into an optical path of the optical lens system;

a driver for inserting the neutral density filter into the optical path when the luminance of the object is higher than the predetermined value; and

a compensator for compensating position of a focal plane of the optical lens system after insertion of the neutral density filter.

2. The image pickup apparatus in accordance with claim 1 further comprising an instruction member for instructing start of image pickup operation, and wherein the driver inserts the neutral density filter into the optical path before the start of the image pickup operation and after the instruction by the movement of the instruction member.

3. The image pickup apparatus in accordance with claim 1, wherein the driver removes the neutral density filter from the optical path after completing the image pickup operation.

4. The image pickup apparatus in accordance with claim 1, wherein the compensator compensates the position of the focal plane of the optical lens system which is focused before the insertion of the neutral density filter.

5. The image pickup apparatus in accordance with claim 1, wherein the compensator compensates the position of the focal plane of the optical lens system corresponding to a defocus quantity due to the insertion of the neutral density filter which is previously calculated.

6. A method for compensating position of focal plane of an optical lens system used in an image pickup apparatus comprising steps of:

sensing a luminance of an object;

judging whether the luminance of the object is higher than a predetermined value or not;

inserting a neutral density filter into an optical path of an optical lens system when the luminance of the object is higher than the predetermined value; and

compensating position of focal plane of the optical lens system after inserting the neutral density filter into the optical path.

7. An image pickup apparatus comprising:

an image pickup device;

an optical lens system;

a luminance sensor for sensing a luminance of an object;

a judging device for judging whether the luminance of the object is higher than a predetermined value or not;

a neutral density filter to be inserted into an optical path of the optical lens system;

a driver for inserting the neutral density filter into the optical path when the luminance of the object is higher than the predetermined value;

a first compensator for compensating output signals from the image pickup device after insertion of the neutral density filter; and

a second compensator for compensating position of a focal plane of the optical lens system after insertion of the neutral density filter.

8. The image pickup apparatus in accordance with claim 7 further comprising an instruction member for instructing start of image pickup operation, and wherein the driver inserts the neutral density filter into the optical path before the start of the image pickup operation and after the instruction by the movement of the instruction member.

9. The image pickup apparatus in accordance with claim 7, wherein the driver removes the neutral density filter from the optical path after completing the image pickup operation.

10. The image pickup apparatus in accordance with claim 7, wherein the first compensator compensates white balance of the output signals from the image pickup device which is previously adjusted before the insertion of the neutral density filter, and the second compensator compensates the position of the focal plane of the optical lens system which is focused before the insertion of the neutral density filter.

11. The image pickup apparatus in accordance with claim 10, wherein the first compensator compensates the white balance corresponding to spectral transmittance of the neutral density filter which is previously measured, and the second compensator compensates the position of the focal plane of the optical lens system corresponding to a defocus quantity due to the insertion of the neutral density filter which is previously calculated.