Methods, systems, and apparatus, including computer programs encoded on computer storage media, for a light-to-frequency sensor conversion. In some implementations, a first output waveform is generated from a light signal, a frequency of the first output waveform being based on an intensity of the light signal, including integrating the light signal across multiple clock cycles. In response to receiving a notification, a hold operation is performed to stop integrating the light signal for a period of time. In response to an end of the hold operation, a second output waveform is generated that includes integrating the intensity of the light signal starting from the end of the hold operation over a count of the multiple clock cycles that start after the end of the hold operation by a delay amount. The first output waveform and the second output waveform are summed to determine the intensity of the light signal.

A photon counting device includes a plurality of pixels each including a photoelectric conversion element configured to convert input light to charge, and an amplifier configured to amplify the charge converted by the photoelectric conversion element and convert the charge to a voltage, an A/D converter configured to convert the voltages output from the amplifiers of the plurality of pixels to digital values; and a conversion unit configured to convert the digital value output from the A/D converter to the number of photons by referring to reference data, for each of the plurality of pixels, and the reference data is created based on a gain and an offset value for each of the plurality of pixels.

A wireless battery-powered daylight sensor for measuring a total light intensity in a space is operable to transmit wireless signals using a variable transmission rate that is dependent upon the total light intensity in the space. The sensor comprises a photosensitive circuit, a wireless transmitter for transmitting the wireless signals, a controller coupled to the photosensitive circuit and the wireless transmitter, and a battery for powering the photosensitive circuit, the wireless transmitter, and the controller. The photosensitive circuit is operable to generate a light intensity control signal in response to the total light intensity in the space. The controller transmits the wireless signals in response to the light intensity control signal using the variable transmission rate that is dependent upon the total light intensity in the space. The variable transmission rate may be dependent upon an amount of change of the total light intensity in the space. In addition, the variable transmission rate may be further dependent upon a rate of change of the total light intensity in the space.

What is disclosed are systems and methods of optical correction for pixel evaluation and correction for active matrix light emitting diode device (AMOLED) and other emissive displays. Optical correction for correcting for non-homogeneity of a display panel uses sparse display test patterns in conjunction with a defocused camera as the measurement device to avoid aliasing (moiré) of the pixels of the display in the captured images.

Certain embodiments provide a self-checking photoelectric sensor that is configured to determine a characteristic (e.g., an amount of blockage and/or wellness/decay) of an optical pathway (e.g., an electro-optical pathway). An example method generally includes increasing, over a time period that starts at a first time, a current input to a light emitting element (LEE). The method generally includes receiving, by a light detection element, an output of the LEE via the optical pathway during the time period. The method generally includes converting, during the time period, the LEE output to a voltage output. The method generally includes determining a second time in the time period when the voltage output crosses a threshold. The method generally includes determining the characteristic of the optical pathway between the LEE and the light detection element based on a difference between the second time and the first time.

An on/off switching circuit includes an on/off switch switchable between an on state and an off state, an light emitting diode (LED) driver to power one or more LEDs to illuminate an area of interest, a switch control unit to transition the on/off switch between the on and off states, the switch control unit including a light sensing circuit comprising at least one LED of the LEDs as a light sensor, and a bi-directional gate circuit. When the on/off switch is in the off state the bi-directional gate is in a first conducting state in which the bi-directional gate circuit connects the light sensor to the light sensing circuit, and when the on/off switch is in the on state the bi-directional gate is in a second conducting state in which the bi-directional gate connects the LED driver to the one or more LEDs including the light sensor.

An apparatus for controlling a frequency analysis processing includes: a memory; and a processor coupled to the memory and configured to execute a fast Fourier transform process that includes performing a fast Fourier transform operation on data of two groups into which sensor data sensed at a first sampling frequency by a sensor is divided, and execute a change process that includes changing, in a case where results of butterfly operations of the fast Fourier transform operation are similar between the two groups, a sampling frequency at which the sensor operates to a second sampling frequency lower than the first sampling frequency.

A first brightness value and a second brightness value are determined. The first brightness value relates to display performed by the display during a display time window. The second brightness value relates to an off state of the display during an off time window. The display is off during the off time window. A first drop depth value is determined according to the first brightness value and the second brightness value. A second ambient brightness value is acquired by adjusting a first ambient brightness value detected by the light sensor based on a brightness adjusting model acquired under predetermined ambient light and the first drop depth value.

A safety control system includes: a first control unit arranged to control a controlled system, a second control unit arranged to detect a fault with the controlled system and arranged to transmit messages wirelessly to the first control unit, wherein the second control unit includes: a first controller and a second controller, each of the first and second controllers being arranged to detect a condition of the controlled system and output messages indicative of whether or not the condition has been detected; a transmitter arranged to transmit wirelessly to the first control unit; and a multiplexer arranged to connect each of the first and second controllers in turn to the transmitter so that messages from each of the first and second controllers can be transmitted to the first control unit.

A compound sensor system includes a first sensor, a second sensor, a memory that stores a module, and a processor coupled to the first sensor, the second sensor, and the memory. The first sensor is configured to detect a parameter that indicates a likelihood of having a user enter or leave a target area, and, in response, send a first command signal to the processor. The processor is configured to receive the first command signal from the first sensor and send a second command signal to the second sensor based on receiving the first command signal. The second sensor is configured to operate at a sleep mode and switch to an active mode upon receiving the second command signal, and during the active mode the second sensor is configured to determine if the user enters or leaves the target area.