A system of taking images of different sensitivities at the same time uses both an image sensor, and an auxiliary part to the image sensor. The image sensor element can be a photogate, and the auxiliary part can be the floating diffusion associated with the photogate. Both the photogate and the floating diffusion accumulate charge. Both are sampled at different times. The floating diffusion provides a lower sensitivity amount of charge than the photogate itself. The system can have a photogate and floating diffusion in each pixel along with a select transistor, a reset transistor, and a follower transistor. All of this circuitry can be formed of CMOS for example. The system can also operate in a column/parallel mode, where each column of the photo sensor array can have a column signal processor which samples and holds the reset signal, the floating diffusion signal and the photogate signal.
An image sensor formed on an integrated circuit is disclosed. The image sensor comprises an array of pixels including a plurality of bright pixels and a plurality of dark pixels. The image sensor also includes a dark exposure control circuit for controlling the exposure time of the plurality of dark pixels and a bright exposure control circuit for controlling the exposure time of the plurality of bright pixels.
An energy selective radiation sensor has a photodetector and a transfer gate for controlling transfer of charge from the photodetector to a first sense node. A first readout circuit is provided for reading out charge from the first node. In use a first charge accumulated in the photodetector from a first predetermined portion of an energy spectrum of a radiation source is transferred to the first sense node. A second charge is accumulated in the photodetector from a second predetermined portion of the energy spectrum. The first charge is readout from the first sense node with the readout circuit, the second charge transferred to the first sense node and likewise readout. In embodiments of the invention, a second sense node and second transfer gate are provided and the first charge is read out through a first sense node and the second charge through the second sense node. In further embodiments a dump drain controlled by a dump gate is also provided to permit duty cycle control of sensitivity of the photodetector by selectively dumping and storing of charge accumulated in the photodetector.
A pixel structure is described, comprising at least two selection switches coupled in series to improve the yield of the pixel. Also an array comprising such pixel structures logically organized in rows and columns is described, as well as a method for selecting a row or column of pixel structures in such an array.
An image apparatus and method is disclosed for extending the dynamic range of an image sensor. A first linear pixel circuit produces a first pixel output signal based on charge integration by a first photo-conversion device over a first integration period. A second linear pixel circuit produces a second pixel output signal based on charge integration by a second photo-conversion device over a second integration period, where the second integration period is shorter than the first integration period. A sample-and-hold circuit captures signals representing the first and second pixel output signals.
A pixel structure is described, comprising at least two selection switches coupled in series to improve the yield of the pixel. Also an array comprising such pixel structures logically organized in rows and columns is described, as well as a method for selecting a row or column of pixel structures in such an array.
