Device for controlling imaging device

• US 5,477,265 A
• Filed: 05/31/1994
• Issued: 12/19/1995
• Est. Priority Date: 05/25/1990
• Status: Expired due to Term

• Current Assignee: PENTAX RICOH IMAGING COMPANY, LTD.
• Original Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Inventors: Tani, Nobuhiro
• Primary Examiner(s): Mancuso, Joseph
• Assistant Examiner(s): Shalwala, Bipin
• Application Number:
  US08/251,675
• Time in Patent Office: 567 Days
• Field of Search: 348/297, 348/223, 348/224, 348/243, 348/244, 348/241
• US Class Current: 348/241
• CPC Class Codes: H04N 2101/00 Still video cameras
• CPC Class Codes: H04N 23/75 by influencing optical camera components
• CPC Class Codes: H04N 25/622 by controlling anti-blooming drains
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/71 Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
• CPC Class Codes: H04N 25/73 using interline transfer [IT]

Abstract

A control device includes a control mechanism for eliminating a dark current effect generated in a CCD. The control mechanism carries out a charge pumping operation in the CCD during a time after an object is photographed up until the time when an aperture is closed. The control mechanism obtains a dark current component generated when the aperture is closed after a photographing operation, based on a dark current component outputted by the CCD during a predetermined period, and then subtracts the dark current component from data outputted by the CCD in accordance with an image signal corresponding to the subject.

Claims

1. A device for controlling an imaging device which outputs an image signal corresponding to an object, comprising:

a mechanically operated aperture that controls an exposure of said object; and

means for removing a dark current that is generated during an operating time required for said aperture to move to a completely closed position from an open position upon initiation of a closing of an aperture command, said operating time comprising a variable time, said removing means comprising;

a detecting device that detects an amount of dark current that exists during a predetermined time period, where the predetermined time period is prior to an initiation of a closing of said aperture;

a storage device that stores said detected amount of dark current;

a control device that obtains an amount of dark current generated during said operating time, based upon said detected amount of dark current and said operating time; and

a subtractor that subtracts said amount of dark current obtained by said control device, to thereby eliminate an effect of said dark current.

2. The device of claim 1, wherein said storage device stores digital data representing said detected dark current.

3. The device of claim 1, wherein said imaging device comprises a CCD.

4. The device of claim 1, further comprising a device that drives said aperture.

5. The device of claim 1, wherein said device is used with an electronic camera.

6. The device of claim 1, wherein said control device calculates said dark current component according to an equation:

space="preserve" listing-type="equation">I=IR·

TF/2

wherein

TF corresponds to a time when said aperture is completely closed from said open position;

2 refers to a 2-field period;

IR equals said dark current stored in said storage device; and

I equals said dark current generated for said 2-field period.