Signal processing device, controlling method, image sensing device, and electronic device
The present technology relates to a signal processing device, a controlling method, an image sensing device, and an electronic device capable of inhibiting deterioration in image quality of a captured image. The signal processing device of the present technology connects an output of a comparing unit which compares a signal read from a unit pixel with reference voltage to a floating diffusion of the unit pixel, thereby feeding back the output of the comparing unit to the floating diffusion as a reset level, and disconnects the output of the comparing unit from the floating diffusion of the unit pixel, thereby allowing the floating diffusion to maintain the reset level. The present technology may be applied to the image sensing device and the electronic device, for example.
1. A signal processing device comprising:
a connection control unit which controls connection between an output of a comparing unit which compares a signal read from a unit pixel with reference voltage and a floating diffusion of the unit pixel; and
a connection unit which connects or disconnects the output of the comparing unit to or from the floating diffusion of the unit pixel according to control of the connection control unit, wherein the connection unit connects or disconnects the output of the comparing unit to or from a reset transistor connected to the floating diffusion of the unit pixel according to the control of the connection control unit.
2. The signal processing device according to claim 1 , wherein
the connection unit includes a MOSFET which drives as a switch to connect or disconnect the output of the comparing unit to or from the floating diffusion of the unit pixel on a basis of a control signal supplied from the connection control unit.
3. The signal processing device according to claim 1 , wherein
the connection unit is provided for each column of unit pixels for a pixel array in which a plurality of unit pixels is arranged in a matrix.
4. The signal processing device according to claim 3 , wherein
a plurality of unit pixel units formed of some unit pixels of the pixel array is formed in the pixel array, and
the connection unit is provided for each column of the unit pixels for each unit pixel unit.
5. The signal processing device according to claim 4 , wherein
the connection control unit controls the connection unit to connect the output of the comparing unit to the floating diffusion of the unit pixel, thereby feeding back the output of the comparing unit to the floating diffusion as a reset level, and thereafter controls the connection unit to disconnect the output of the comparing unit from the floating diffusion of the unit pixel, thereby allowing the floating diffusion to maintain the reset level.
6. The signal processing device according to claim 5 , further comprising:
a reset control unit which controls operation of the reset transistor for each row of the unit pixels, wherein
the reset control unit connects the reset transistor of a current row of the unit pixels of the pixel array,
the connection control unit thereafter controls the connection unit to sequentially connect the output of the comparing unit to the floating diffusion of each column of the unit pixels, thereby sequentially feeding back the output of the comparing unit to a floating diffusion of each column of the unit pixels as the reset level, and thereafter controls the connection unit to disconnect the output of the comparing unit from the floating diffusion of the unit pixel, thereby allowing the floating diffusion of the unit pixel to maintain the reset level, and
the reset control unit thereafter further disconnects the reset transistor of the current row of the unit pixels of the pixel array.
7. The signal processing device according to claim 1 , further comprising:
a signal line connection control unit which controls connection between a signal line which transmits the signal read from the unit pixel and an input of the comparing unit; and
a signal line connection unit which connects or disconnects the signal line to or from the input of the comparing unit according to control of the signal line connection control unit.
8. The signal processing device according to claim 7 , wherein
the signal line connection unit is provided for each column of unit pixels for a pixel array in which a plurality of unit pixels is arranged in a matrix.
9. The signal processing device according to claim 8 , wherein
when the connection control unit feeds back the output of the comparing unit to the floating diffusion as a reset level, the signal line connection control unit controls the signal line connection unit of the column of the unit pixels to connect the signal line of the column of the unit pixels to the input of the comparing unit.
10. The signal processing device according to claim 1 , further comprising:
the comparing unit; and
a counter which counts until a comparison result of the comparing unit changes.
11. The signal processing device according to claim 10 , wherein
the comparing unit and the counter are provided for each of a plurality of unit pixel units formed of some unit pixels of a pixel array formed in the pixel array in which a plurality of unit pixels is arranged in a matrix.
12. The signal processing device according to claim 1 , further comprising:
a unit pixel group formed of a plurality of unit pixels.
13. The signal processing device according to claim 12 , wherein
the unit pixel group forms a pixel array in which the plurality of unit pixels is arranged in a matrix, and
the connection unit is provided for each column of the unit pixels for the pixel array.
14. The signal processing device according to claim 13 , wherein
a plurality of unit pixel units formed of some unit pixels of the pixel array is formed in the pixel array, and
the connection unit is provided for each column of the unit pixels for each unit pixel unit.
15. A controlling method comprising:
connecting an output of a comparing unit which compares a signal read from a unit pixel with reference voltage to a floating diffusion of the unit pixel, thereby feeding back the output of the comparing unit to the floating diffusion as a reset level, and
disconnecting the output of the comparing unit from the floating diffusion of the unit pixel, thereby allowing the floating diffusion to maintain the reset level, wherein a connection unit connects or disconnects the output of the comparing unit to or from a reset transistor connected to the floating diffusion of the unit pixel according to control of a connection control unit.
16. An image sensing device comprising:
a pixel array in which a plurality of unit pixels is arranged in a matrix;
a connection control unit which controls connection between an output of a comparing unit which compares a signal read from the unit pixel with reference voltage and a floating diffusion of the unit pixel; and
a connection unit provided for each column of the unit pixels for the pixel array which connects or disconnects the output of the comparing unit to or from the floating diffusion of the unit pixel according to control of the connection control unit, wherein the connection unit connects or disconnects the output of the comparing unit to or from a reset transistor connected to the floating diffusion of the unit pixel according to the control of the connection control unit.
17. The image sensing device according to claim 16 , further comprising:
the comparing unit; and
a counter which counts until a comparison result of the comparing unit changes, wherein
a plurality of unit pixel units formed of some unit pixels of the pixel array is formed in the pixel array,
the comparing unit and the counter are provided for each unit pixel unit, and
the connection unit is provided for each column of the unit pixels for each unit pixel unit.
18. The image sensing device according to claim 17 , including a plurality of semiconductor substrates, wherein
the connection control unit, the connection unit, the comparing unit, and the counter are formed on a semiconductor substrate different from a semiconductor substrate on which the pixel array is formed.
19. An electronic device comprising:
an imaging unit which captures an image of a subject; and
an image processor which performs image processing of image data obtained by imaging by the imaging unit,
the imaging unit including:
a pixel array in which a plurality of unit pixels is arranged in a matrix;
a connection control unit which controls connection between an output of a comparing unit which compares a signal read from the unit pixel with reference voltage and a floating diffusion of the unit pixel; and
a connection unit provided for each column of the unit pixels for the pixel array which connects or disconnects the output of the comparing unit to or from the floating diffusion of the unit pixel according to control of the connection control unit, wherein the connection unit connects or disconnects the output of the comparing unit to or from a reset transistor connected to the floating diffusion of the unit pixel according to the control of the connection control unit.