1. Field of the Invention
The present invention relates to a signal reading apparatus and an image pickup system using the signal reading apparatus.
2. Description of the Related Art
Examples of a signal detection apparatus for detecting a magnetic signal or the like include a photoelectric conversion apparatus for detecting a light. Representative types of this photoelectric conversion apparatus are a CCD type photoelectric conversion apparatus and a MOS type photoelectric conversion apparatus. The MOS type photoelectric conversion apparatus is provided with a pixel unit in which pixels that are unit cells each including a photoelectric conversion element such as a photo diode are arranged two-dimensionally, a capacitance unit for holding a signal from the pixel unit, and a common signal line for outputting a signal from the capacitance unit to the outside.
Japanese Patent Laid-Open No. 2005-020483 discloses a configuration where a plurality of common signal lines are provided and multiplexed. In addition, Japanese Patent Laid-Open No. 2005-086260 discloses a configuration where a capacitance unit is formed into a block for reading.
As disclosed in Japanese Patent Laid-Open No. 2005-020483, by providing the plurality of common signal lines, the speed of reading data is improved. However, an offset due to a variation in the common signal lines may be caused. Furthermore, in a case where the plurality of common signal lines are provided, the number of amplifiers provided to output units is also increased. Thus, the power consumption is increased. Also, depending on a relation with respect to the outside of the photoelectric conversion apparatus, the number of output terminals required for the photoelectric conversion apparatus may be limited in some cases.
USPTO Backgrounds
USPTO Backgrounds