The present disclosure relates generally to apparatus and methods for image sensing, and, more particularly, to a multi-bit quanta image sensor (QIS) having a controllable (e.g., adjustably variable) exposure response characteristic. Some embodiments provide an apparatus and method wherein the non-linearity of the response of a multi-bit QIS is controllable (e.g., selectively variable) by dynamically choosing the bit depth n during AID conversion, and/or later (i.e., post-conversion) by firmware and/or software.

A dynamic vision sensor (DVS) or change detection sensor reacts to changes in light intensity and in this way monitors how a scene changes. This disclosure covers both single pixel and array architectures. The DVS may contain one pixel or 2-dimensional or 1-dimensional array of pixels. The change of intensities registered by pixels are compared, and pixel addresses where the change is positive or negative are recorded and processed. Analyzing frames based on just three values for pixels, increase, decrease or unchanged, the proposed DVS can process visual information much faster than traditional computer vision systems, which correlate multi-bit color or gray level pixel values between successive frames.

Some embodiments provide an apparatus and method wherein the non-linearity of the response of a multi-bit QIS is controllable (e.g., selectively variable) by dynamically choosing the bit depth n during A/D conversion, and/or later (i.e., post-conversion) by firmware and/or software.

The present invention relates to a delta image sensor comprising an arrangement of pixels and a plurality of acquisition circuits corresponding to at least one pixel and formed as part of an integrated circuit. Each acquisition circuit includes at least one sensor circuit comprising a photosensor configured to generate a sensor signal, VSIG, depending on a light signal illuminating the photosensor of the at least one pixel; at least one analogue to digital conversion, A/D, circuit configured to convert a current VSIG to a digital signal; at least one digital storage circuit configured to store a representation of at least one digital signal corresponding to a previous VSIG; at least one digital comparison circuit configured to compare the level of the stored representation with the current VSIG to detect whether a changed level is present; and at least one digital output circuit configured to generate an event output under the condition of the changed level. The sensor circuit is configured to change an analogue function of its read-out characteristics to generate a respective changed VSIG.

An image sensor for detecting time-dependent image data, comprising multiple photovoltaic converters and multiple electronic converters arranged in arrays and linked by switching elements. Each of the photovoltaic converters and one of the electronic converters form a pair that generates digital information dependent on light intensity on the photovoltaic converter. The switching elements are arranged to selectively connect at least two of the photovoltaic converters to one of the electronic converters and at least two of the electronic converters to one of the photovoltaic converters.

An imaging system includes a light sensor, a pulse detection imaging (PDI) circuit, and an image processing unit. The light sensor generates one or both of an image signal and a pulse signal. The pulse PDI circuit includes a first terminal in signal communication with the light sensor to receive one or both of the image signal and the pulse signal and a second terminal in signal communication with a voltage source. The image processing unit is in signal communication with the PDI circuit to receive one or both of the image signal and the pulse signal and to simultaneously perform imagery and pulse detection based on the image signal and the pulse signal, respectively.

In a case where illuminance is high, an error between the number of photons per frame calculated from time information and the number of photons and the actually expected number of photons per frame is reduced. In a time counter that counts a clock from the start of exposure in one frame, one-count time in the clock is switched depending on the illuminance. In a case where a pixel counter is saturated within a period of one frame, the illuminance is determined to be high, and a high-illuminance clock in which one-count time is set more minutely in the first half of one frame is used to count. In a case where the illuminance is not determined to be high, a normal clock is used to count.

Methods of calibrating a linear-logarithmic image sensor pixel include performing a reset of the pixel in advance of establishing a leakage current between a photodiode and a floating diffusion region of the pixel. A first voltage of the floating diffusion region is then read through a source follower and selection transistor, after the leakage is terminated. A step is then performed to transfer charge between the photodiode and the floating diffusion region of the pixel so that a voltage of a cathode of the photodiode is increased. Thereafter, a second voltage of the floating diffusion region is read. The first and second read voltages are then used to perform a calibration operation. These steps may be repeated to establish another leakage current of different duration/magnitude and yield third and fourth read voltages, which support further calibration.

Examples of image sensors are described herein. In an example, an image sensor may comprise an array of hybrid pixels, where each hybrid pixel includes light sensing unit and a non-volatile memory component coupled to the light sensing unit. The light sensing unit comprises a light detecting element and a charge to voltage conversion unit. The charge to voltage conversion unit is to provide an output pixel signal (V.sub.PD), based on photo-electrons generated by the light detecting element. Further, the non-volatile component when calibrated to an initial resistance state is to compress the output pixel signal (V.sub.PD) during exposure.

A photosensitive pixel with gain stage is disclosed. The photosensitive pixel with gain stage may receive an input light stimulus and output a corresponding output voltage in response to the input light stimulus. The output voltage may correspond linearly to the magnitude of the input light stimulus over a linear operating region and logarithmically to the magnitude of the input light stimulus over a logarithmic operating region. In this manner, the photosensitive pixel with gain stage may be both sensitive to input light stimuli over the linear operating region and may exhibit dynamic range enabling non-saturated response to input light stimuli over the logarithmic operating region.