Abstract: Fixed pattern noise (FPN) reduction techniques in image sensors operated with pulse illumination are disclosed herein. In one embodiment, a method includes, during a first sub-exposure period of a frame, (a) operating a first tap of a pixel to capture a first signal corresponding to first charge at a first floating diffusion, the first charge corresponding to first light incident on a photosensor, and (b) operating a second tap of the pixel to capture a first parasitic signal corresponding to FPN at a second floating diffusion. The method further includes, during a second sub-exposure period of the frame, (a) operating the second tap to capture a second signal corresponding to second charge at the second floating diffusion, the second charge corresponding to second light incident on the photosensor, and (b) operating the first tap to capture a second parasitic signal corresponding to FPN at the first floating diffusion.

Abstract: Low power event driven pixels and reset control circuits for the same are disclosed herein. In one embodiment, an event driven pixel comprises a photosensor; a photocurrent-to-voltage converter coupled to the photosensor; and a difference circuit coupled to the photocurrent-to-voltage converter. The difference circuit includes a source follower transistor and is configured to generate a signal at a gate of the source follower transistor that is based on a voltage output from the photocurrent-to-voltage converter. The difference circuit is further configured to output a difference signal in response to assertion of a row select signal. The event driven pixel can further include a reset control circuit coupled to the difference circuit and configured to initialize the difference circuit, and to reset the difference circuit when the difference signal output from the event driven pixel indicates a change in the voltage greater than a threshold amount.

Abstract: Event vision sensors with defect pixel suppression (and associated methods) are disclosed herein. In one embodiment, an event vision sensor includes an array of event vision pixels and an event signal processor. The event signal processor is configured to identify event vision pixels of the array that are defective based on noise event occurrence firing rates corresponding to the event vision pixels. The noise event occurrence firing rate for each event vision pixel can be based on inter-arrival times or a noise event rate corresponding to that event vision pixel. Each event vision pixel can include internal circuitry (e.g., a memory component, such as a latch) that can, when the event vision pixel is identified as defective, be used to disable the event vision pixel from detecting events or to mask an output of the event vision pixel such that events are not read out of the event vision pixel.

Abstract: Event vision sensors with defect pixel suppression (and associated methods) are disclosed herein. In one embodiment, an event vision sensor includes an array of event vision pixels and an event signal processor. The event signal processor is configured to identify event vision pixels of the array that are defective based on noise event occurrence firing rates corresponding to the event vision pixels. The noise event occurrence firing rate for each event vision pixel can be based on measurements of a probability of that event vision pixel detecting a noise event over time. Each event vision pixel can include internal circuitry (e.g., a memory component, such as a latch) that can, when the event vision pixel is identified as defective, be used to disable the event vision pixel from detecting events or to mask an output of the event vision pixel such that events are not read out of the pixel.

Abstract: An image sensor comprises: a control block generating a video interface enabled signal, a video interface for receiving the video interface enabled signal, a pixel array for providing a video stream to the video interface, an output port for receiving the video stream from the video interface and outputting the video stream to outside of the image sensor, a stream indicator pin for receiving the video interface enabled signal from the control block when the video interface is receiving the video interface enabled signal from the control block, where a terminal of the video interface receiving the video interface enabled signal is connected to the stream indicator pin by a conductor, and they are sealed in a package of the image sensor.

Abstract: An image sensor comprises: a control block generating a video interface enabled signal, a video interface for receiving the video interface enabled signal, a pixel array for providing a video stream to the video interface, an output port for receiving the video stream from the video interface and outputting the video stream to outside of the image sensor, a stream indicator pin for receiving the video interface enabled signal from the control block when the video interface is receiving the video interface enabled signal from the control block, where a terminal of the video interface receiving the video interface enabled signal is connected to the stream indicator pin by a conductor, and they are sealed in a package of the image sensor.

Abstract: Methods for transmitting asynchronous event data via synchronous communications interfaces (and associated imaging systems) are disclosed herein. In one embodiment, an imager comprises an array of event vision pixels, a synchronous communications transmitter configured to transmit frames of data to a synchronous communications receiver, and a timer configured to indicate when a threshold amount of time has elapsed. The pixels can generate event data based on activity within an external scene. The imager can be configured to insert available event data into a payload of the current frame during a first time period before the frame timer indicates that the threshold amount of time has elapsed, pad the payload with dummy data during a second time period after the frame timer indicates that the threshold amount of time has elapsed, and transmit (using the synchronous communications transmitter) the current frame of data to the synchronous communications receiver.

Abstract: A time-of-flight pixel array includes first transistors to transfer a first phase portion of charge from photodiodes responsive to reflected modulated light during a first subframe, and a second phase portion of the charge during a second subframe. The second phase is an inverted first phase. Second transistors transfer the second phase portion of the charge during the first subframe, and the first phase portion of the charge during the second subframe. Third transistors transfer a third phase portion of the charge during the first subframe, and a fourth phase portion of the charge during the second subframe. The fourth phase is an inverted third phase. The third phase is ninety degrees out of phase with the first phase. Fourth transistors transfer the fourth phase portion of the charge during the first subframe, and the third phase portion of the charge during the second subframe.

Abstract: Event vision sensors with event data compression (and associated systems, devices, and methods) are disclosed herein. In one embodiment, an event vision sensor includes a plurality of event vision pixels. Each event vision pixel of the plurality is configured to generate event data based on events indicated in incident light received from an external scene, and includes a compression circuit configured to compress the event data prior to readout of the event data from the event vision pixel. Each compression circuit can include a time aggregation circuit that is configured to track a number of the events detected by the corresponding event vision pixel over a specified timing window. The compressed event data can be read out from the event vision sensors and used to generate a pseudo-frame. The event vision sensor can optionally perform frame-level compression on the pseudo-frame.

Abstract: A pixel circuit includes a photodiode configured to photogenerate charge in response to reflected modulated light incident upon the photodiode. A first floating diffusion is configured to store a first portion of charge photogenerated in the photodiode. A first transfer transistor is configured to transfer the first portion of charge from the photodiode to the first floating diffusion in response to a first phase signal. A first storage node is configured to store the first portion of charge from the first floating diffusion. A first decoupling circuit has a first output responsive to a first input. The first input is coupled to the first floating diffusion and the first output is coupled to first storage node. A voltage swing at the first output is greater than a voltage swing at the first input.

Abstract: An image sensor has diffractive microlenses over pixels with central structures and ring(s) of material having index of refraction different from that of background material. Disposed beneath the diffractive microlenses are photodiodes that permit determining ratios of illumination of peripheral photodiodes to illumination of central photodiodes of the pixels, and, in embodiments, circuitry for determining said ratio. In embodiments, the ratio is used to find illumination wavelengths; and in other embodiments the ratio is used to determine focus of an imaging lens providing illumination. A method determines color by passing light through a diffractive lens disposed above photodiodes of the diffractive pixel and determining color from illumination peripheral and central photodiodes. An autofocus method of determining focus includes passing light through a diffractive lens and determining focus from illumination of peripheral photodiodes and central photodiodes of the pixel.

Abstract: Methods for transmitting asynchronous event data via synchronous communications interfaces (and associated imaging systems) are disclosed herein. In one embodiment, an imager comprises an array of event vision pixels, a synchronous communications transmitter configured to transmit frames of data to a synchronous communications receiver, and a timer configured to indicate when a threshold amount of time has elapsed. The pixels can generate event data based on activity within an external scene. The imager can be configured to insert available event data into a payload of the current frame during a first time period before the frame timer indicates that the threshold amount of time has elapsed, pad the payload with dummy data during a second time period after the frame timer indicates that the threshold amount of time has elapsed, and transmit (using the synchronous communications transmitter) the current frame of data to the synchronous communications receiver.

Abstract: Methods for transmitting asynchronous event data via synchronous communications interfaces (and associated imaging systems) are disclosed herein. In one embodiment, an imager comprises an array of event vision pixels, and a synchronous communications transmitter configured to transmit frames of data to a synchronous communications receiver. The pixels generate event data based on activity within an external scene. The imager communicates, at a first time and to the receiver, an anticipated amount of data that will be included in a frame transmitted to the receiver at a second time. The anticipated amount of data can be based on a prediction of an amount of event data that will be generated at a future point in time for transmission to the receiver in the frame. The imager can then transmit the frame to the receiver at the second time with an amount of data corresponding to the anticipated amount of data.

Abstract: A pixel circuit includes a photodiode configured to photogenerate charge in response to reflected modulated light incident upon the photodiode. A first floating diffusion is configured to store a first portion of charge photogenerated in the photodiode. A first transfer transistor is configured to transfer the first portion of charge from the photodiode to the first floating diffusion in response to a first phase signal. A first storage node is configured to store the first portion of charge from the first floating diffusion. A first decoupling circuit has a first output responsive to a first input. The first input is coupled to the first floating diffusion and the first output is coupled to first storage node. A voltage swing at the first output is greater than a voltage swing at the first input.

Abstract: In some embodiments, an image sensor is provided. A signal processing unit of the image sensor is configured with executable instructions that cause the signal processing unit to perform actions comprising: reading a captured scene from a pixel array; reading a value from a test initiation register; in response to determining that the value indicates a test mode: processing the captured scene to detect a region of interest associated with the value; and providing the region of interest to a first interface for transmission to a host device; and in response to determining that the value does not indicate the test mode: analyzing the captured scene using a computer vision technique to selectively generate a signal based on the analysis of the captured scene; and selectively providing the signal to a second interface for transmission to the host device.

Abstract: A device has a first and second PPD sensor configured for placement over an artery; a camera between the first and second PPD sensors; and a processor having memory with firmware for determining pulse transit time (PTT) between the PPD sensors, and determines blood pressure (BP) therefrom using a calibrated conversion from PTT to BP. The firmware also obtains initial and subsequent images of the artery, extracts features, and adjusts calibrated conversion from PTT to BP based upon features extracted from the initial and subsequent images of the artery. In embodiments the processor enhances the initial and subsequent images of the artery using a structured light tomographic enhancement process. A method uses first and second PPD sensors placed over an artery to determine pulse transit time; obtains initial and subsequent images of the artery with a camera; and uses features extracted from the initial and subsequent images of the artery to adjust a calibrated conversion from PTT to BP.

Abstract: Low power event driven pixels with passive, differential difference detection circuitry (and reset control circuits for the same) are disclosed herein. In one embodiment, an event driven pixel comprises a photosensor, a photocurrent-to-voltage converter, and a difference circuit. The difference circuit includes (a) a first circuit branch configured to sample a reference light level based on a voltage output by the photocurrent-to-voltage converter, and to output a first analog light level onto a first column line that is based on the reference light level; and (b) a second circuit branch configured to sample a light level based on the voltage, and to output a second analog light level onto a second column line that is based on the light level. A difference between the second analog light level and the first analog light level indicates whether the event driven pixel has detected an event in an external scene.

Abstract: A time-of-flight pixel array includes photodiodes that generate charge in response to incident reflected modulated light. First transfer transistors transfer a first portion of the charge from the photodiodes in response to a first modulation signal and second transfer transistors transfer a second portion of the charge from the photodiodes in response to a second modulation signal, which is an inverted first modulation signal. First floating diffusions are coupled to the first transfer transistors. A binning transistor is coupled between one of the first floating diffusions and another one of the first floating diffusions. A first memory node is coupled to one of the first floating diffusions through a first sample and hold transistor and a second memory node is coupled to another one of the first floating diffusions through a second sample and hold transistor.

Abstract: In some embodiments, an image sensor is provided. A signal processing unit of the image sensor is configured with executable instructions that cause the signal processing unit to perform actions comprising: reading a captured scene from a pixel array; reading a value from a test initiation register; in response to determining that the value indicates a test mode: processing the captured scene to detect a region of interest associated with the value; and providing the region of interest to a first interface for transmission to a host device; and in response to determining that the value does not indicate the test mode: analyzing the captured scene using a computer vision technique to selectively generate a signal based on the analysis of the captured scene; and selectively providing the signal to a second interface for transmission to the host device.

Abstract: Fixed pattern noise (FPN) reduction techniques in image sensors operated with pulse illumination are disclosed herein. In one embodiment, a method includes, during a first sub-exposure period of a frame, (a) operating a first tap of a pixel to capture a first signal corresponding to first charge at a first floating diffusion, the first charge corresponding to first light incident on a photosensor, and (b) operating a second tap of the pixel to capture a first parasitic signal corresponding to FPN at a second floating diffusion. The method further includes, during a second sub-exposure period of the frame, (a) operating the second tap to capture a second signal corresponding to second charge at the second floating diffusion, the second charge corresponding to second light incident on the photosensor, and (b) operating the first tap to capture a second parasitic signal corresponding to FPN at the first floating diffusion.