Time of flight sensing unit and time of flight sensing system

Abstract

The invention provides a time of flight sensing unit and a time of flight sensing system. A time of flight pixel cell includes a photosensor to sense photons reflected from an object. Pixel support circuitry including charging control logic is coupled to the photosensor to detect when the photosensor senses the photons reflected from the object, and coupled to receive timing signals representative of when light pulses are emitted from a light source. A controllable current source is coupled to receive a time of flight signal form the charging control logic to provide a charge current when a light pulse emitted from the light source until the photosensor senses a respective one of the photons reflected from the object. A capacitor is coupled to receive the charge current, and a voltage on the capacitor is representative of a round trip distance to the object. A reset circuit is coupled to reset the voltage on the capacitor after being charged a plurality number of times.

Description

technical field [0001] The present invention relates to image sensors. In particular, embodiments of the invention relate to three-dimensional image sensors. Background technique [0002] Interest in three-dimensional (3D) cameras is increasing as popular 3D applications continue to grow in applications such as imaging, movies, games, computers, user interfaces, and the like. A typical passive approach to creating 3D images is to use multiple cameras to capture stereo or multiple images. With stereo images, objects in the image are triangulated to create a 3D image. One disadvantage of this triangulation technique is that it is difficult to create 3D images using small devices because there must be a minimum separation distance between each camera in order to create a three-dimensional image. Additionally, this technique is complex and thus requires significant computer processing power in order to create 3D images in real time. [0003] For applications requiring real-t...

AI Technical Summary

Problems solved by technology

Since real-time applications require such short response times, susceptibility to noise, jitter, clock signals, heat, etc. in systems for acquiring 3D images becomes increasingly challenging as the required response time decreases

A further challenge is also presented when the sensor of the 3D image acquisition system does not detect the light reflected back from the object

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