Light sensor with increased dynamic range
First Claim
1. In an image capture system having a sensor, the sensor having a plurality of pixel cells each having a first node and a second node and a third node and a fourth node, a method of capturing image data from a selected pixel cell, comprising:
- performing two captures at the same time on the selected pixel cell with one capture having a longer integration time period than another, by a) resetting the second node of the selected pixel cell;
b) resetting the first node of the selected pixel cell; and
then c) collecting an image on the first node of the selected pixel cell; and
then d) transferring a first pixel value from the first node to the second node after a first predetermined nonzero time period being the integration time period of one capture during which the image is collected on the first node but not the second node; and
then e) reading a second pixel value from the first node via the third node of the selected pixel cell, and reading the first pixel value from the second node via the fourth node of the selected pixel cell, after a second predetermined nonzero time period that follows the first time period and during which the image is collected on the first node, a sum of the first and second time periods being the longer integration time period of another capture; and
f) performing an arithmetic operation on the first pixel value and the second pixel value to generate a result; and
g) providing the result as a value of the selected pixel cell, to the image capture system.
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Abstract
In an image capture system having a sensor with a first node and a second node, a method of capturing image data is disclosed. The first node is reset. The second node is reset. An image is collected on the first node. A first pixel value is then transferred from the first node to the second node after a first predetermined time period. The first pixel value and a second pixel value is then provided after a second predetermined time period. An arithmetic operation is performed on the first pixel value and the second pixel value. A system for performing the method is also disclosed.
42 Citations
28 Claims
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1. In an image capture system having a sensor, the sensor having a plurality of pixel cells each having a first node and a second node and a third node and a fourth node, a method of capturing image data from a selected pixel cell, comprising:
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performing two captures at the same time on the selected pixel cell with one capture having a longer integration time period than another, by a) resetting the second node of the selected pixel cell;
b) resetting the first node of the selected pixel cell; and
thenc) collecting an image on the first node of the selected pixel cell; and
thend) transferring a first pixel value from the first node to the second node after a first predetermined nonzero time period being the integration time period of one capture during which the image is collected on the first node but not the second node; and
thene) reading a second pixel value from the first node via the third node of the selected pixel cell, and reading the first pixel value from the second node via the fourth node of the selected pixel cell, after a second predetermined nonzero time period that follows the first time period and during which the image is collected on the first node, a sum of the first and second time periods being the longer integration time period of another capture; and
f) performing an arithmetic operation on the first pixel value and the second pixel value to generate a result; and
g) providing the result as a value of the selected pixel cell, to the image capture system. - View Dependent Claims (2, 3, 4, 5, 19)
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6. In an image capture system having a sensor and a controller for controlling the sensor, the sensor including a pixel array having a plurality of pixel cells arranged in rows and columns, each pixel cell having a first node for collecting an image, a second node, a third node and a fourth node, a focal plane processor for processing a first pixel value and a second pixel value, a method of capturing image data from a selected pixel cell, comprising:
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performing two captures at the same time on the selected pixel cell with one capture having a longer integration time period than another, by a) the controller asserting a second reset signal to reset the second node to a predetermined value;
b) the controller asserting a first reset signal to reset the first node to a predetermined value; and
thenc) the pixel cell collecting an image on the first node represented by the first pixel value, and not on the second node; and
thend) the controller asserting a first transfer signal to transfer the first pixel value from the first node to be stored at the second node after a first predetermined time period being the integration time period of one capture during which the image is collected on the first node; and
thene) the controller asserting a first readout signal to read the second pixel value from the first node via the third node and to provide a second readout signal to read the first pixel value stored at the second node via the fourth node, after a second predetermined time period that follows the first time period and during which the image is collected on the first node, a sum of the first and second time periods being the longer integration time period of another capture; and
thenf) the focal plane processor performing an arithmetic operation on the first pixel value and the second pixel value to generate a result; and
theng) the focal plane processor providing the result, as a value of the selected pixel, to the image capture system. - View Dependent Claims (7, 8, 9, 10, 11, 20)
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12. An image capture system comprising:
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a) a sensor for capturing image data having i) a pixel array having a plurality of pixel cells arranged in rows and columns, each pixel cell having a first node for collecting image data, a second node, a third node, and a fourth node;
ii) a first data conductor, coupled to the third node for communicating a first pixel value from each of a group of pixel cells in one of a row and a column of the array;
iii) a second data conductor, coupled to the fourth node for communicating a second pixel value from each of the group of pixel cells;
iv) a focal plane processor coupled to the first data conductor and the second data conductor for receiving the first pixel value and the second pixel value, respectively, and responsive thereto performing an arithmetic operation on the first pixel value and the second pixel value to generate a result, the focal plane processor having an output for providing the result;
v) an interface circuit, coupled to the output of each focal plane processor, for interfacing the focal plane processor to a bus; and
b) a controller, coupled to the sensor, for controlling the sensor for managing the transfer of data from the pixel cell to the focal plane processor, for controlling the focal plane processor, for managing the transfer of data from the focal plane processor to the interface circuit, for controlling the interface circuit and for managing the transfer of data to the bus;
wherein the controller controls the sensor to generate a value representing the image detected by a selected pixel cell by performing two captures at the same time on the selected pixel cell with one capture having a longer integration time period than another to yield the first and second pixel values having different, nonzero integration times, the first and second pixel values being obtained by the first node of the selected pixel, the second pixel value being stored at the second node prior to being transferred to the fourth node. - View Dependent Claims (13, 14, 15, 16, 17, 18, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification