SOLID-STATE IMAGE PICKUP DEVICE, METHOD OF DRIVING SOLID-STATE IMAGE PICKUP DEVICE, AND ELECTRONIC INSTRUMENT

• US 20120153125A1
• Filed: 12/06/2011
• Published: 06/21/2012
• Est. Priority Date: 12/15/2010
• Status: Active Grant

• Current Assignee: Sony Semiconductor Solutions Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Oike, Yusuke, Sakano, Yorito, Mabuchi, Keiji
• Granted Patent: US 9,054,009 B2
• Time in Patent Office: Days
• US Class Current: 250/208.1
• CPC Class Codes: H01L 27/14612 involving a transistor
• CPC Class Codes: H01L 27/14656 Overflow drain structures
• CPC Class Codes: H04N 25/53 Control of the integration time
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS
• CPC Class Codes: H04N 25/533 by using differing integration times for different sensor regions
• CPC Class Codes: H04N 25/709 Circuitry for control of the power supply
• CPC Class Codes: H04N 25/771 comprising storage means other than floating diffusion

Abstract

A CMOS image sensor has an image array as a matrix of unit pixels each including at least a photodiode, a memory for holding a charge stored in the photodiode, a floating diffusion region for converting the charge in the memory into a voltage, a first transfer gate for transferring the charge from the photodiode to the memory, a second transfer gate for transferring the charge from the memory to the floating diffusion region, and a resetting transistor for resetting the charge in the floating diffusion region. The unit pixels are driven to set the potential of a potential barrier at a boundary between the memory and the floating diffusion region to a potential such that a charge overflowing the memory is transferred to the floating diffusion region, when the first transfer gate is turned on. The CMOS image sensor operates in a global shutter mode for capturing moving images.

Claims

1. A solid-state image pickup device comprising:

a plurality of pixels each including at least

a photoelectric transducer,

a charge holder configured to hold a charge stored in said photoelectric transducer,

a charge voltage converter configured to convert the charge held by said charge holder into a voltage,

a first transfer element configured to transfer the charge from said photoelectric transducer to said charge holder,

a second transfer element configured to transfer the charge from said charge holder to said charge voltage converter, and

a resetter configured to reset the charge in said charge voltage converter; and

a drive controller configured to control driving of said unit pixels, wherein

when said drive controller turns on said first transfer element, said drive controller applies, to said second transfer element, a first transfer voltage which sets the potential of a potential barrier at a boundary between said charge holder and said charge voltage converter to a first potential which is lower than the potential in a depleted state of a photodetector of said photoelectric transducer such that a charge overflowing said charge holder is transferred to said charge voltage converter.

2. The solid-state image pickup device according to claim 1, wherein before said drive controller turns off said first transfer element, said drive controller turns off said second transfer element from the first transfer voltage.

3. The solid-state image pickup device according to claim 1, wherein before said drive controller turns off said first transfer element, said drive controller applies, to said second transfer element, a second transfer voltage which sets the potential of the potential barrier at the boundary between said charge holder and said charge voltage converter to a second potential which is higher than the potential in the depleted state of the photodetector of said photoelectric transducer and which is lower than a potential barrier around said charge holder.

4. The solid-state image pickup device according to claim 3, wherein before said drive controller turns off said second transfer element from the second transfer voltage, said drive controller turns off said first transfer element.

5. The solid-state image pickup device according to claim 1, wherein said drive controller applies a negative voltage to said first transfer element and said second transfer element when said first transfer element and said second transfer element are turned off.

6. The solid-state image pickup device according to claim 5, further comprising:

a voltage reader configured to read a voltage corresponding to the charge in said charge voltage converter;

wherein said drive controller controls driving of said unit pixels to enable said voltage reader to

read a voltage as a first signal level corresponding to the charge in said charge voltage converter,

read a voltage as a reset level corresponding to the charge in said charge voltage converter which is reset by said resetter, and

read a voltage as a second signal level corresponding to the charge transferred from said charge holder to said charge voltage converter by said second transfer element after the charge in said charge voltage converter is reset by said resetter.

7. The solid-state image pickup device according to claim 6, further comprising:

a calculator configured to calculate a first difference between said first signal level and said reset level which are read by said voltage reader and a second difference between said second signal level and said reset level which are read by said voltage reader, and adds said first difference and said second difference to each other.

8. The solid-state image pickup device according to claim 7, wherein said calculator adds said first difference and said second difference to each other if said second signal level is greater than a predetermined level.

9. A solid-state image pickup device comprising:

a plurality of pixels each including at least

a photoelectric transducer,

a charge holder configured to hold a charge stored in said photoelectric transducer,

a charge voltage converter configured to convert the charge held by said charge holder into a voltage,

a first transfer element configured to transfer the charge from said photoelectric transducer to said charge holder,

a second transfer element configured to transfer the charge from said charge holder to said charge voltage converter, and

a resetter configured to reset the charge in said charge voltage converter; and

a drive controller configured to control driving of said unit pixels, wherein

when said drive controller turns on said first transfer element, said drive controller applies, to said second transfer element, a transfer voltage which sets the potential of a potential barrier at a boundary between said charge holder and said charge voltage converter to a potential which is higher than the potential in a depleted state of a photodetector of said photoelectric transducer and which is lower than a potential barrier around said charge holder, and

before said drive controller turns off said second transfer element from the transfer voltage, said drive controller turns off said first transfer element.

10. The solid-state image pickup device according to claim 9, wherein said drive controller applies a negative voltage to said first transfer element and said second transfer element when said first transfer element and said second transfer element are turned off.

11. The solid-state image pickup device according to claim 10, further comprising:

a voltage reader configured to read a voltage corresponding to the charge in said charge voltage converter;

wherein said drive controller controls driving of said unit pixels to enable said voltage reader to

read a voltage as a first signal level corresponding to the charge in said charge voltage converter,

read a voltage as a reset level corresponding to the charge in said charge voltage converter which is reset by said resetter, and

read a voltage as a second signal level corresponding to the charge transferred from said charge holder to said charge voltage converter by said second transfer element after the charge in said charge voltage converter is reset by said resetter.

12. The solid-state image pickup device according to claim 11, further comprising:

a calculator configured to calculate a first difference between said first signal level and said reset level which are read by said voltage reader and a second difference between said second signal level and said reset level which are read by said voltage reader, and adds said first difference and said second difference to each other.

13. The solid-state image pickup device according to claim 12, wherein said calculator adds said first difference and said second difference to each other if said second signal level is greater than a predetermined level.

14. A method of driving a solid-state image pickup device including

a plurality of pixels each including at least

a photoelectric transducer,

a charge configured to hold a charge stored in said photoelectric transducer,

a charge voltage converter configured to convert the charge held by said charge holder into a voltage,

a first transfer element configured to transfer the charge from said photoelectric transducer to said charge holder,

a second transfer element configured to transfer the charge from said charge holder to said charge voltage converter, and

a resetter configured to reset the charge in said charge voltage converter, and

a drive controller which controls driving of said unit pixels, wherein

said method comprises:

when said drive controller turns on said first transfer element, applying, to said second transfer element, a first transfer voltage which sets the potential of a potential barrier at a boundary between said charge holder and said charge voltage converter to a first potential which is lower than the potential in a depleted state of a photodetector of said photoelectric transducer such that a charge overflowing said charge holder is transferred to said charge voltage converter.

15. A method of driving a solid-state image pickup device including

a plurality of pixels each including at least

a photoelectric transducer,

a charge holder configured to hold a charge stored in said photoelectric transducer,

a charge voltage converter configured to convert the charge held by said charge holder into a voltage,

a first transfer element configured to transfer the charge from said photoelectric transducer to said charge holder,

a second transfer element configured to transfer the charge from said charge holder to said charge voltage converter, and

a resetter configured to reset the charge in said charge voltage converter, and

a drive controller configured to control driving of said unit pixels, wherein

said method comprises:

when said drive controller turns on said first transfer element, applying, to said second transfer element, a transfer voltage which sets the potential of a potential barrier at a boundary between said charge holder and said charge voltage converter to a potential which is higher than the potential in a depleted state of a photodetector of said photoelectric transducer and which is lower than a potential barrier around said charge holder; and

before said drive controller turns off said second transfer element from the transfer voltage, turning off said first transfer element.

16. An electronic instrument comprising:

a solid-state image pickup device including

a plurality of pixels each including at least

a photoelectric transducer,

a charge holder configured to hold a charge stored in said photoelectric transducer,

a charge voltage converter configured to convert the charge held by said charge holder into a voltage,

a first transfer element configured to transfer the charge from said photoelectric transducer to said charge holder,

a second transfer element configured to transfer the charge from said charge holder to said charge voltage converter, and

a resetter configured to reset the charge in said charge voltage converter, and

a drive controller configured to control driving of said unit pixels, wherein

when said drive controller turns on said first transfer element, said drive controller applies, to said second transfer element, a first transfer voltage which sets the potential of a potential barrier at a boundary between said charge holder and said charge voltage converter to a first potential which is lower than the potential in a depleted state of a photodetector of said photoelectric transducer such that a charge overflowing said charge holder is transferred to said charge voltage converter.

17. An electronic instrument comprising:

a solid-state image pickup device including

a plurality of pixels each including at least

a photoelectric transducer,

a charge holder configured to hold a charge stored in said photoelectric transducer,

a charge voltage converter configured to convert the charge held by said charge holder into a voltage,

a first transfer element configured to transfer the charge from said photoelectric transducer to said charge holder,

a second transfer element configured to transfer the charge from said charge holder to said charge voltage converter, and

a resetter configured to reset the charge in said charge voltage converter, and

a drive controller configured to control driving of said unit pixels, wherein

when said drive controller turns on said first transfer element, said drive controller applies, to said second transfer element, a transfer voltage which sets the potential of a potential barrier at a boundary between said charge holder and said charge voltage converter to a potential which is higher than the potential in a depleted state of a photodetector of said photoelectric transducer and which is lower than a potential barrier around said charge holder, and

before said drive controller turns off said second transfer element from the transfer voltage, said drive controller turns off said first transfer element.