| US 7,569,868 B2 | ||
| Image pickup device and image pickup system | ||
| Takanori Watanabe, Yamato (Japan); Tetsuya Itano, Zama (Japan); and Mahito Shinohara, Tokyo (Japan) | ||
| Assigned to Canon Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on Jun. 05, 2006, as Appl. No. 11/446,119. | ||
| Claims priority of application No. 2005-169780 (JP), filed on Jun. 09, 2005; and application No. 2006-146796 (JP), filed on May 26, 2006. | ||
| Prior Publication US 2006/0279650 A1, Dec. 14, 2006 | ||
| Int. Cl. H04N 5/335 (2006.01) | ||
| U.S. Cl. 257—184 [257/187; 257/259; 257/292; 257/461; 348/307] | 7 Claims |

| 1. An image pickup device, comprising:
a plurality of pixels, each including a photoelectric conversion element converting light into charges;
a transfer gate that transfers the converted charges to a floating node;
a first transistor that outputs a signal based on a voltage of the floating node to a source thereof, and a second transistor
that resets the voltage of the floating node;
a signal line to which the first transistor is connected through the source, and to which the first transistor outputs a signal
through the source;
a clipping circuit including at least a third transistor having a source connected to the signal line to which the first transistor
is connected through the source, and being capable of suppressing a fluctuation of a voltage of the signal line at a first
voltage and a second voltage different from the first voltage, and
a constant current source being capable of supplying a current from a drain to the source of the first transistor or a drain
to the source of the third transistor,
wherein a reset signal reading period for reading a signal based on a voltage of the floating node at the time of reset of
the floating node, and a photoelectric conversion signal reading period for reading a signal based on a voltage of the floating
node at the time of transferring the charges from the photoelectric conversion element to the floating node are set,
the clipping circuit suppressing the fluctuation of the voltage of the signal line to the first voltage during a period of
at least a part of the reset signal reading period, and suppresses the fluctuation of the voltage of the signal line to the
second voltage during a period of at least a part of the photoelectric conversion signal reading period, and
wherein the first voltage is higher than the second voltage, and the second voltage is set so as not to turn off the constant
current source.
|