Image sensor and control method for image sensor
The present technology relates to an image sensor and a control method for an image sensor which are capable of measuring illuminance of each color in an image sensor. Each of a plurality of pixel units includes a pixel and a reset transistor, and the pixel includes a photoelectric converting unit that performs photoelectric conversion on light of a certain color incident through a color filter and a transfer transistor that transfers charges obtained by the photoelectric conversion of the photoelectric converting unit and is controllable for each color. According to control of the transfer transistor, the charges are read from the photoelectric converting unit through the transfer transistor and the reset transistor, and a voltage corresponding to the charges is supplied to an AD converting unit connected to the reset transistor. The present technology can be applied to, for example, an image sensor that photographs an image.
1. An image sensor, comprising:
a plurality of pixel units, respective ones of which include a pixel and a reset transistor,
wherein the respective pixel includes a photoelectric converting unit configured to perform photoelectric conversion on light of a certain color incident through a color filter and a transfer transistor configured to transfer charges obtained by the photoelectric conversion of the photoelectric converting unit, wherein the respective pixel is controllable for each color,
the respective reset transistor is connected to an analog to digital (AD) converting unit configured to perform AD conversion, the respective reset transistor configured to reset the charges,
according to control of the transfer transistor, the charges are read from the photoelectric converting unit through the transfer transistor and the reset transistor, and a voltage corresponding to the charges is supplied to the AD converting unit connected to the respective reset transistor,
the AD converting unit is connected to a power line that connects a drain of the respective reset transistor with a power source, and
the image sensor further comprises a conversion control unit configured to cause the power line to enter a floating state, to cause the charges to flow to the power line in the floating state through the respective reset transistor, converts the charges to the voltage, and to supply the voltage to the AD converting unit connected to the power line.
2. The image sensor according to claim 1 ,
wherein as the transfer transistor is controlled for each color, the voltage corresponding to the charges is supplied to the AD converting unit for the each color.
3. The image sensor according to claim 1 , further comprising:
a driver configured to control the transfer transistor such that the charges are transferred from the photoelectric converting unit; and
a plurality of nodes that connect a gate of the transfer transistor to a GND,
wherein a driver controlling the transfer transistor such that the charges are transferred uses one of the plurality of nodes, and
a driver not controlling the transfer transistor such that the charges are transferred uses another of the plurality of nodes.
4. The image sensor according to claim 1 ,
wherein the conversion control unit includes a step-down unit that generates a stepped-down voltage obtained by stepping down a voltage of the power source, and
the conversion control unit is configured to apply the stepped-down voltage to the power line connected with the respective reset transistor in the on state, and then to cause the power line to enter the floating state.
5. The image sensor according to claim 4 , further comprising,
a clamp unit configured to clamp the power line to a certain voltage lower than the stepped-down voltage.
6. The image sensor according to claim 1 ,
wherein the pixel unit includes a plurality of pixels, and
the respective reset transistor is shared by the plurality of pixels.
7. A control method for an image sensor including a plurality of pixel units respective ones of which include a pixel and a reset transistor, wherein the respective pixel includes a photoelectric converting unit configured to perform photoelectric conversion on light of a certain color incident through a color filter and a transfer transistor configured to transfer charges obtained by the photoelectric conversion of the photoelectric converting unit, wherein the respective pixel is controllable for each color, the respective reset transistor is connected to an analog to digital (AD) converting unit configured to perform AD conversion, and to reset the charges, and the AD converting unit is connected to a power line that connects a drain of the respective reset transistor with a power source, the control method comprising:
reading the charges from the photoelectric converting unit through the transfer transistor and the reset transistor and supplying a voltage corresponding to the charges to the AD converting unit connected to the reset transistor, according to control of the transfer transistor; and
by a conversion control unit, causing the power line to enter a floating state, causing the charges to flow to the power line in the floating state through the respective, converting the charges to the voltage, and supplying the voltage to the AD converting unit connected to the power line.
8. The control method according to claim 7 , further comprising: as the transfer transistor is controlled for each color, supplying the voltage corresponding to the charges to the AD converting unit for the each color.
9. The control method according to claim 7 , wherein the image sensor further comprises:
a driver configured to control the transfer transistor such that the charges are transferred from the photoelectric converting unit; and
a plurality of nodes that connect a gate of the transfer transistor to a GND,
wherein a driver controlling the transfer transistor such that the charges are transferred uses one of the plurality of nodes, and
a driver not controlling the transfer transistor such that the charges are transferred uses another of the plurality of nodes.
10. The control method according to claim 7 , wherein
the conversion control unit includes a step-down unit that generates a stepped-down voltage obtained by stepping down a voltage of the power source, and
the conversion control unit is configured to apply the stepped-down voltage to the power line connected with the respective reset transistor in the on state, and then to cause the power line to enter the floating state.
11. The control method according to claim 10 , wherein the image sensor further includes a clamp unit configured to clamp the power line to a certain voltage lower than the stepped-down voltage.
12. The control method according to claim 7 ,
wherein the pixel unit includes a plurality of pixels, and
the respective reset transistor is shared by the plurality of pixels.
13. A non-transitory computer readable medium storing a program that, when executed by a computer, causes the computer to perform control operations for an image sensor including a plurality of pixel units respective ones of which include a pixel and a reset transistor, wherein the respective pixel includes a photoelectric converting unit configured to perform photoelectric conversion on light of a certain color incident through a color filter and a transfer transistor configured to transfer charges obtained by the photoelectric conversion of the photoelectric converting unit, wherein the respective pixel is controllable for each color, the respective reset transistor is connected to an analog to digital (AD) converting unit configured to perform AD conversion, and to reset the charges, and the AD converting unit is connected to a power line that connects a drain of the respective reset transistor with a power source, the operations comprising:
reading the charges from the photoelectric converting unit through the transfer transistor and the reset transistor and supplying a voltage corresponding to the charges to the AD converting unit connected to the reset transistor, according to control of the transfer transistor; and
by a conversion control unit, causing the power line to enter a floating state, causing the charges to flow to the power line in the floating state through the respective, converting the charges to the voltage, and supplying the voltage to the AD converting unit connected to the power line.
14. The non-transitory computer readable medium according to claim 13 , the operations further comprising: as the transfer transistor is controlled for each color, supplying the voltage corresponding to the charges to the AD converting unit for the each color.
15. The non-transitory computer readable medium according to claim 13 , wherein the image sensor further comprises:
a driver configured to control the transfer transistor such that the charges are transferred from the photoelectric converting unit; and
a plurality of nodes that connect a gate of the transfer transistor to a GND,
wherein a driver controlling the transfer transistor such that the charges are transferred uses one of the plurality of nodes, and
a driver not controlling the transfer transistor such that the charges are transferred uses another of the plurality of nodes.
16. The non-transitory computer readable medium according to claim 13 , wherein
the conversion control unit includes a step-down unit that generates a stepped-down voltage obtained by stepping down a voltage of the power source, and
the conversion control unit is configured to apply the stepped-down voltage to the power line connected with the respective reset transistor in the on state, and then to cause the power line to enter the floating state.
17. The non-transitory computer readable medium according to claim 16 , wherein the image sensor further includes a clamp unit configured to clamp the power line to a certain voltage lower than the stepped-down voltage.
18. The non-transitory computer readable medium according to claim 13 ,
wherein the pixel unit includes a plurality of pixels, and
the respective reset transistor is shared by the plurality of pixels.