Vision Sensor, a Method of Vision Sensing, and a Depth Sensor Assembly

According to the present invention there is provided a vision sensor comprising, an array of pixels comprising rows and columns of pixels, wherein each pixel in the array comprises, a photosensor which is configured to output a current proportional to the intensity of light which is incident on the photosensor; a current source which is configured such that it can output a current which has a constant current level which is equal to the current level of the current output by the photosensor at a selected first instant in time, and can maintain that constant current level even if the level of the current output from the photosensor changes after said selected first instant in time; an integrator which is configured to integrate the difference between the level of current output by the current source and the level of current output by the photosensor, after the selected first instant in time; wherein the vision sensor further comprises a counter which can measure time, wherein the counter is configured such that it can begin to measure time at the selected first instant; and wherein each pixel in the array further comprises a storage means which can store the value on the counter at a second instant in time, the second instant in time being the instant when the integration of the difference between the level of current output by the current source and the level of current output by the photosensor of that pixel reaches a predefined threshold level. There is further provided a corresponding method of vision sensing, and a depth sensor assembly which comprises the vision sensor.