Solid-state image pickup device and method for driving the same in a number of modes
A system and method for driving a solid-state image pickup device including a pixel array unit including unit pixels. Each unit pixel includes a photoelectric converter, column signal lines and a number of analog-digital converting units. The unit pixels are selectively controlled in units of rows. Analog signals output from the unit pixels in a row selected by the selective control though the column signal lines are converted to digital signals via the analog-digital converting units. The digital signals are added among a number of unit pixels via the analog-digital converting units. The added digital signals from the analog-digital converting units are read. Each unit pixel in the pixel array unit is selectively controlled in units of arbitrary rows, the analog-distal converting units being operable to performing the converting in a (a) normal-frame-rate mode and a (b) high-frame-rate mode in response to control signals.
1. A method for driving a solid-state image pickup device comprising a pixel array unit including unit pixels which are two-dimensionally arranged in a matrix pattern, each unit pixel including a photoelectric converter, and column signal lines corresponding to respective columns of the matrix pattern and a plurality of analog-digital converting units, each analog-digital converting unit being connected to a respective column signal line, the unit pixels being selectively controlled in units of rows, and the method comprising:
converting analog signals output from the unit pixels in a row selected by the selective control through the column signal lines to digital signals via the analog-digital converting units,
adding the digital signals among a plurality of unit pixels via the analog-digital converting units in response to operation in a high-frame-rate mode, and
reading the added digital signals from the analog-digital converting units, wherein each unit pixel in the pixel array unit is selectively controlled in units of arbitrary rows, the analog-digital converting units being operable to perform the converting in a (a) normal-frame-rate mode and the (b) high-frame-rate mode in response to control signals.
2. The method according to claim 1 , wherein in the (a) normal-frame-rate mode a signal read from a unit pixel of the unit pixels is a comparison time of a first reading and is measured by performing a down count during a first reading operation and a comparison time of a second reading is measured by performing an up count during the second reading operation;
in the (b) high-frame-rate mode a count result on the unit pixel is held, once a unit pixel in a next row is being converted a down count is performed on the count result at the first reading operation and an up count is performed at a second reading operation to measure a comparison time at the second reading.