Abstract: Techniques are provided for x-ray sensing for intraoral tomography. A methodology implementing the techniques according to an embodiment includes detecting an x-ray pulse based on energy received at one or more pixels of a pixel array. The method also includes integrating the energy received at each of the pixels of the array of pixels, in response to the detection, wherein the energy received at each of the pixels is associated with the x-ray pulse. The method further includes multiplexing readouts of analog signals from the array of pixels into two or more parallel channels. The method further includes simultaneously converting (or otherwise in parallel) the analog signals of each of the channels into digital signals and storing the digital signals in memory as frames of data. The method may further include, for example, transmitting the frames of data from the memory, over a Universal Serial Bus, to an imaging system.

Abstract: Techniques are provided for x-ray onset detection for an intraoral dental sensor. A methodology implementing the techniques according to an embodiment includes calculating a plurality of superpixel values for each of a plurality of rows of detector pixels of a sensor. Each of the superpixel values is based on a sum of pixel values of a set of pixels associated with the superpixel value, the set of pixels selected from the detection row of a current frame of the sensor. The method also includes calculating a difference between each of the superpixel values and a corresponding stored superpixel value generated from a previous sensor frame and determining if the differences exceed a superpixel threshold value. The method further includes incrementing a hit counter in response to the determination and generating a detection signal if the hit counter exceeds a hit count threshold, otherwise proceeding to process the next detection row.

Abstract: Techniques are provided for x-ray sensing for intraoral tomography. A methodology implementing the techniques according to an embodiment includes detecting an x-ray pulse based on energy received at one or more pixels of a pixel array. The method also includes integrating the energy received at each of the pixels of the array of pixels, in response to the detection, wherein the energy received at each of the pixels is associated with the x-ray pulse. The method further includes multiplexing readouts of analog signals from the array of pixels into two or more parallel channels. The method further includes simultaneously converting (or otherwise in parallel) the analog signals of each of the channels into digital signals and storing the digital signals in memory as frames of data. The method may further include, for example, transmitting the frames of data from the memory, over a Universal Serial Bus, to an imaging system.

Abstract: Techniques are provided for x-ray image data monitoring and signaling for patient safety. A methodology implementing the techniques according to an embodiment includes integrating energy associated with a received x-ray pulse at an array of pixels. The method also includes multiplexing a readout of the integrated energy from the array of pixels, as analog signals, into channels, and performing analog to digital conversion of the analog signals of the channels into digital signals. The method further includes generating an error indicator in response to determining that a calculated mean of the digital signals is either greater than an upper threshold value associated with saturation or less than a lower threshold value associated with underexposure. The method further includes transmitting the error indicator over a Universal Serial Bus, to an imaging system, to terminate transmission of further x-ray pulses.

Abstract: A pixel sensor, an imaging array that includes such pixel sensors, and a method for operating an imaging array are disclosed. The pixel sensor includes a transfer gate that connects a photodiode to a floating diffusion node in response to a transfer signal, a reset circuit, and a controller. The reset circuit is adapted to apply either a first potential or a second potential to the floating diffusion node, the second potential being less than the first potential. The controller is configured to cause the reset circuit to apply the first potential to the floating diffusion node while the transfer gate is conducting just prior to a start of an accumulation phase, and then apply the second potential to the floating diffusion node after the transfer gate is rendered non-conducting, the second potential is less than the first potential.

Abstract: A pixel sensor, an imaging array that includes such pixel sensors, and a method for operating an imaging array are disclosed. The pixel sensor includes a transfer gate that connects a photodiode to a floating diffusion node in response to a transfer signal, a reset circuit, and a controller. The reset circuit is adapted to apply either a first potential or a second potential to the floating diffusion node, the second potential being less than the first potential. The controller is configured to cause the reset circuit to apply the first potential to the floating diffusion node while the transfer gate is conducting just prior to a start of an accumulation phase, and then apply the second potential to the floating diffusion node after the transfer gate is rendered non-conducting, the second potential is less than the first potential.

Abstract: An imaging array having a plurality of pixel sensors connected to a bit line is disclosed. Each pixel sensor includes a first photodetector having a photodiode, a floating diffusion node, and an amplifier. The floating diffusion node is characterized by a parasitic photodiode and parasitic capacitance. The amplifier amplifies a voltage on the floating diffusion node to produce a signal on an amplifier output. The first photodetector also includes a bit line gate that connects the amplifier output to the bit line in response to a row select signal and a voltage dividing capacitor having a first terminal connected to the floating diffusion node and a second terminal connected to a drive source that switches a voltage on the second terminal between a drive potential different from ground and ground in response to a drive control signal.

Abstract: An imaging array having a plurality of pixel sensors connected to a bit line is disclosed. Each pixel sensor includes a first photodetector having a photodiode, a floating diffusion node, and an amplifier. The floating diffusion node is characterized by a parasitic photodiode and parasitic capacitance. The amplifier amplifies a voltage on the floating diffusion node to produce a signal on an amplifier output. The first photodetector also includes a bit line gate that connects the amplifier output to the bit line in response to a row select signal and a voltage dividing capacitor having a first terminal connected to the floating diffusion node and a second terminal connected to a drive source that switches a voltage on the second terminal between a drive potential different from ground and ground in response to a drive control signal.

Abstract: An apparatus having a rectangular imaging array characterized by a plurality of pixel sensors and a plurality of readout lines is disclosed. The apparatus has a plurality of column processing circuits, each column processing circuit being connected to a corresponding one of the readout lines and a plurality of signal injectors, one signal injector being connected to each of the readout lines. Each signal injector causes one of a predetermined number of voltages to be coupled to that readout line. An exposure for each of the pixel sensors is determined during image recording periods. The signal injectors inject a plurality of calibration voltages into the readout lines during calibration periods, and determines a gain function of an amplifier in one of the column processing circuits by measuring an output of the amplifier for the plurality of calibration voltages, the calibration period is between the imaging recording periods.

Abstract: An apparatus having a rectangular imaging array characterized by a plurality of pixel sensors and a plurality of readout lines is disclosed. The apparatus has a plurality of column processing circuits, each column processing circuit being connected to a corresponding one of the readout lines and a plurality of signal injectors, one signal injector being connected to each of the readout lines. Each signal injector causes one of a predetermined number of voltages to be coupled to that readout line. An exposure for each of the pixel sensors is determined during image recording periods. The signal injectors inject a plurality of calibration voltages into the readout lines during calibration periods, and determines a gain function of an amplifier in one of the column processing circuits by measuring an output of the amplifier for the plurality of calibration voltages, the calibration period is between the imaging recording periods.

Abstract: An imaging sensor using a novel bit line processing circuit, that circuit, and the method of processing the pixel outputs from an image sensor using that processing circuit are disclosed. The image sensor includes an array of pixel sensors, a signal digitizing circuit, and a digitizing controller. Each pixel sensor generates a voltage signal that is a function of a charge on the photodetector in that pixel sensor, and couples that voltage signal to a bit line in response to a first signal. The signal digitizing circuit is connected to the bit line, the digitizing circuit converting the voltage signal to a plurality of output digital values, the output digital values having selectable levels of digitization noise. The digitizing controller generates the level of noise based on the voltage signal. The signal digitizing circuit includes a variable gain amplifier and an ADC having a fixed number of bits.

Abstract: An imaging sensor using a novel bit line processing circuit, that circuit, and the method of processing the pixel outputs from an image sensor using that processing circuit are disclosed. The image sensor includes an array of pixel sensors, a signal digitizing circuit, and a digitizing controller. Each pixel sensor generates a voltage signal that is a function of a charge on the photodetector in that pixel sensor, and couples that voltage signal to a bit line in response to a first signal. The signal digitizing circuit is connected to the bit line, the digitizing circuit converting the voltage signal to a plurality of output digital values, the output digital values having selectable levels of digitization noise. The digitizing controller generates the level of noise based on the voltage signal. The signal digitizing circuit includes a variable gain amplifier and an ADC having a fixed number of bits.