Image sensor and image sensing system with redundant data
An image sensor including a pixel unit in which a plurality of pixels are arranged in a matrix, an A/D conversion circuit provided corresponding to each column of the matrix and configured to A/D-convert a pixel signal output from the pixel unit and output digital data corresponding to the pixel signal, a memory provided on each column, and a redundant data generation unit configured to generate redundant data based on a generating rule of an error correction code for the digital data, wherein the digital data and the redundant data are stored in the memory.
1. An image sensor comprising:
a pixel unit in which a plurality of pixels are arranged in a matrix;
an A/D conversion circuit provided corresponding to each column of the matrix and configured to A/D-convert a pixel signal output from the pixel unit and output digital data corresponding to the pixel signal, the A/D conversion circuit including a comparator configured to compare the signal from the pixel with a reference signal;
a counter circuit configured to count a reference clock and generate a count signal;
a redundant data generation unit configured to generate redundant data for correcting the digital data by encoding the count signal based on a generating rule of an error correction code; and
a memory configured to store the count signal as the digital signal and the redundant data in accordance with an output signal from the comparator.
2. The sensor according to claim 1 , wherein the digital data is a data expressed in a gray code, and the redundant data generation unit generates redundant data based on a generating rule of an error correction code for the gray code.
3. The sensor according to claim 1 , wherein the digital data is divided into a plurality of blocks, and the redundant data generation unit generates redundant data for each of the plurality of blocks based on a generating rule of an error correction code.
4. The sensor according to claim 1 , wherein the redundant data generation unit generates redundant data for only bits except for a least significant bit among a plurality of bits consisting the digital data.
5. The sensor according to claim 1 , wherein the error correction code is a BCH code.
6. The sensor according to claim 1 , wherein the error correction code is a Hamming code.
7. The sensor according to claim 1 , wherein the error correction code is a Reed-Solomon code.
8. The sensor according to claim 1 , wherein the comparator operates in synchronism with the reference clock.
9. The sensor according to claim 1 , wherein the counter circuit outputs the count signal expressed in a gray code.
10. The sensor according to claim 1 , further comprising a digital signal processing unit configured to process data stored in the memory,
wherein the digital signal processing unit performs error correction for the data based on a decoding rule of the error correction code.
11. The sensor according to claim 1 , wherein the sensor outputs the digital data and the redundant data.
12. An image sensing system comprising:
an image sensor; and
an image signal processing unit configured to generate image data by processing an output signal from the image sensor,
wherein the image sensor comprises:
a pixel unit in which a plurality of pixels are arranged in a matrix;
an A/D conversion circuit provided corresponding to each column of the matrix and configured to A/D-convert a pixel signal output from the pixel unit and output digital data corresponding to the pixel signal, the A/D conversion circuit including a comparator configured to compare the signal from the pixel with a reference signal;
a counter circuit configured to count a reference clock and generate a count signal;
a redundant data generation unit configured to generate redundant data for correcting the digital data by encoding the count signal based on a generating rule of an error correction code; and
a memory configured to store the count signal as the digital signal and the redundant data in accordance with an output signal from the comparator.