Solid-state imaging apparatus with lowered overflow drain bias, method for driving same and camera using same

• US 6,559,889 B2
• Filed: 09/18/1997
• Issued: 05/06/2003
• Est. Priority Date: 09/20/1996
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Hirota, Isao, Tanaka, Hiroaki
• Primary Examiner(s): HO, TUAN V
• Application Number:
  US08/933,533
• Publication Number:
  US 20010010553A1
• Time in Patent Office: 2,056 Days
• Field of Search: 348/296, 348/297, 348/298, 348/299, 348/311, 348/312, 348/314, 348/317, 348/362, 257/230, 257/229
• US Class Current: 348/299
• CPC Class Codes: H01L 27/14812 Special geometry or disposition of pixel-elements, address lines or gate-electrodes
• CPC Class Codes: H01L 27/14818 Optical shielding
• CPC Class Codes: H01L 27/14843 Interline transfer
• CPC Class Codes: H01L 27/14887 Blooming suppression
• CPC Class Codes: H04N 25/42 by switching between different modes of operation using different resolutions or aspect ratios, e.g. switching between interlaced and non-interlaced mode
• CPC Class Codes: H04N 25/57 Control of the dynamic range
• CPC Class Codes: H04N 25/73 using interline transfer [IT]

Abstract

In a CCD imaging device in which sensor sections have the vertical overflow drain (OFD) structure, a substrate bias control signal is applied to the base of a bipolar transistor via a resistor to turn on the transistor at least during a signal charge readout period. As a result, the base potential of a bipolar transistor that constitutes a clamping circuit is lowered, whereby a substrate bias that is output from a substrate bias generation circuit is lowered. Thus, the potential of an overflow barrier in the sensor sections is reduced.

Claims

1. A solid-state imaging apparatus comprising:

a solid-state imaging device having a plurality of sensor sections that have an overflow drain structure and are arranged in matrix form, and a charge transfer section for transferring signal charges read out from the sensor sections;

a shutter effective to prevent light from irradiating the sensor sections; and

a driving system for performing a drive operation so as to lower an overflow drain bias of the solid-state imaging device directly in response to a timing signal, in anticipation of a decrease in a saturation signal charge amount of said sensor sections, and regardless of the amount of incident light during an exposure period, wherein said overflow drain bias is lowered at least during a signal charge readout period in a given operating mode during which said signal charges are read out from said sensor sections, said shutter being closed during said readout period, thereby increasing the saturation signal charge amount of said sensors sections.

2. The solid-state imaging apparatus according to claim 1, wherein in the driving system a start point of lowering the overflow drain bias is set before a start of an exposure.

3. The solid-state imaging apparatus according to claim 1, wherein in the driving system a start point of lowering the overflow drain bias is set within an exposure period.

4. The solid-state imaging apparatus according to claim 1, wherein in the driving system a start point of lowering the overflow drain bias is set within a period from readout of signal charges in a first field to readout of signal charges in a second field.

5. The solid-state imaging apparatus according to claim 1, wherein in the driving system a start point of lowering the overflow drain bias is set within a period from completion of an exposure to readout of signal charges.

6. The solid-state imaging apparatus of claim 1, including a substrate bias voltage generating circuit, said driving system being configured such that said driving system generates a substrate bias control signal which is applied to said substrate bias voltage generating circuit at least during said readout period to effect such lowering of the overflow drain bias.

7. The solid-state imaging apparatus of claim 6, wherein said substrate bias control signal is applied to said substrate bias voltage generating circuit during a time period beginning before said shutter is closed.

8. The solid-state imaging apparatus of claim 6, wherein said substrate bias control signal is applied to said substrate bias voltage generating circuit during a time period beginning after said shutter is closed.

9. The solid-state imaging apparatus of claim 6, wherein said substrate bias control signal is applied to said substrate bias voltage generating circuit during a time period ending when said shutter is reopened.

10. The solid-state imaging apparatus according to claim 1, wherein said overflow drain bias is lowered by a predetermined amount.

11. The solid-state imaging apparatus of claim 1 wherein said driving system performs a drive operation so as to switch said overflow drain bias of the solid-state imaging device between two states.

12. A method for driving a solid-state imaging apparatus comprising a solid-state imaging device having a plurality of sensor sections that have an overflow drain structure and are arranged in matrix form, and a charge transfer section for transferring signal charges read out from the sensor sections, the method comprising the steps of:

lowering an overflow drain bias of the solid-state imaging device directly in response to a timing signal, in anticipation of a decrease in a saturation signal charge amount of said sensor sections, and regardless of the amount of incident light during an exposure period, wherein said lowering occurs at least during a signal readout period in a given operation mode, thereby increasing the saturation signal charge amount of said sensors sections; and

closing a shutter to prevent light from irradiating the sensors.

13. The driving method according to claim 12, wherein a start point of lowering the overflow drain bias is set before a start of an exposure.

14. The driving method according to claim 12, wherein a start point of lowering the overflow drain bias is set within an exposure period.

15. The driving method according to claim 12, wherein a start point of lowering the overflow drain bias is set within a period from readout of signal charges in a first field to readout of signal charges in a second field.

16. The driving method according to claim 12, wherein a start point of lowering the overflow drain bias is set within a period from completion of an exposure to readout of signal charges.

17. The method of claim 12, comprising the further step of generating a substrate bias control signal and applying same to a substrate bias voltage generating circuit at least during said readout period to effect such lowering of the overflow drain bias.

18. The method of claim 17, comprising the further step of generating a substrate bias control signal and applying same to a substrate bias voltage generating circuit during a time period beginning before said shutter is closed.

19. The method of claim 17, comprising the further step of generating a substrate bias control signal and applying same to a substrate bias voltage generating circuit during a time period beginning after said shutter is closed.

20. The solid-state imaging apparatus of claim 17, wherein said substrate bias control signal is applied to said substrate bias voltage generating circuit during a time period ending when said shutter is reopened.

21. The driving method according to claim 12 wherein the lowering step comprises lowering said overflow drain bias by a predetermined amount.

22. The method for driving a solid-state imaging apparatus of claim 12 wherein said lowering step comprises switching said overflow drain bias of the solid-state imaging device between two states at least during a signal readout period in a given operation mode, thereby increasing saturation signal charge amount of said sensors.

23. A camera comprising:

a solid-state imaging device having a plurality of sensor sections that have an overflow drain structure and are arranged in matrix form, and a charge transfer section for transferring signal charges read out from the sensor sections; and

a driving system for performing a drive operation so as to lower an overflow drain bias of the solid-state imaging device directly in response to a timing signal, in anticipation of a decrease in a saturation signal charge amount of said sensor sections, and regardless of the amount of incident light during an exposure period, wherein said overflow drain bias is lowered at least during a signal charge readout period in a given operating mode during which said signal charges are readout from said sensor sections, thereby increasing the saturation signal charge amount of said sensors sections;

an optical system for guiding light to an imaging area of the solid-state imaging device; and

light interrupting means for determining an exposure period by interrupting the light incident to prevent it from reaching the imaging area of the solid-state imaging device, said light interrupting means including a shutter which is closed during said readout period.

24. The camera of claim 23, further comprising a substrate bias voltage generating circuit associated with said solid-state imaging device, said driving system being configured such that said driving system generates a substrate bias control signal which is applied to said substrate bias voltage generating circuit at least during said readout period to effect such lowering of the overflow drain bias.

25. The camera of claim 24, wherein said substrate bias control signal is applied to said substrate bias voltage generating circuit during a time period beginning before said shutter is closed.

26. The camera of claim 24, wherein said substrate bias control signal is applied to said substrate bias voltage generating circuit during a time period beginning after said shutter is closed.

27. The camera of claim 24, wherein said substrate bias control signal is applied to said substrate bias voltage generating circuit during a time period ending when said shutter is reopened.

28. The camera of claim 23, wherein said overflow drain bias is lowered by a predetermined amount.

29. The camera of claim 23 wherein said driving system performs a drive operation so as to switch said overflow drain bias of the solid-state imaging device between two states.