IMAGE SENSING APPARATUS AND CONTROL METHOD THEREFOR

• US 20100053380A1
• Filed: 07/24/2009
• Published: 03/04/2010
• Est. Priority Date: 08/27/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ise, Makoto
• Granted Patent: US 8,174,589 B2
• Time in Patent Office: Days
• US Class Current: 348/241
• CPC Class Codes: H04N 25/617 for reducing electromagnetic interference, e.g. clocking noise
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/677 for reducing the column or line fixed pattern noise

Abstract

A period of periodical noise caused by a period of a drive signal of a CMOS sensor and a period of a signal generated by driving of a circuit other than the CMOS sensor is acquired, and a length of a horizontal blanking period is adjusted so that one horizontal period of a drive signal of the CMOS sensor becomes an integer multiple of the periodical noise period. Then, column noise is detected from an image signal read out by driving the CMOS sensor with a drive signal based on one horizontal period after the adjustment and the detected column noise is subtracted from the image signal.

Claims

1. An image sensing apparatus comprising:

an acquisition unit that acquires a period of periodical noise caused by a period of a drive signal of an image sensor and a period of a signal generated by driving of a circuit other than the image sensor;

a control unit that adjusts a length of a horizontal blanking period so that one horizontal period of a drive signal of the image sensor becomes an integer multiple of the period of the periodical noise;

a column noise detection unit that detects column noise from an image signal read out by driving the image sensor with a drive signal based on one horizontal period after the adjustment by the control unit; and

a column noise reduction unit that subtracts column noise detected by the column noise detection unit from the image signal.

2. The image sensing apparatus according to claim 1, further comprising a driving unit that drives the image sensor so as to read out image signals at a predetermined frame rate from the image sensor,

wherein the control unit adjusts a length of a vertical blanking period so that one vertical period of a drive signal of the image sensor becomes the predetermined frame rate.

3. A control method of an image sensing apparatus comprising:

an acquisition step of acquiring a period of periodical noise caused by a period of a drive signal of an image sensor and a period of a signal generated by driving of a circuit other than the image sensor;

a first adjustment step of adjusting a length of a horizontal blanking period so that one horizontal period of a drive signal of the image sensor becomes an integer multiple of the period of the periodical noise;

a column noise detection step of detecting column noise from an image signal read out by driving the image sensor with a drive signal based on one horizontal period after the adjustment in the first adjustment step; and

a column noise reduction step of subtracting column noise detected in the column noise detection step from the image signal.

4. The image sensing apparatus control method according to claim 3, further comprising:

a readout step of reading out an image signal at a predetermined frame rate from the image sensor; and

a second adjustment step of adjusting a length of a vertical blanking period so that one vertical period of a drive signal of the image sensor becomes the predetermined frame rate.