Time-of-flight depth camera and single-frequency modulation-demodulation noise-reducing distance measuring method

Abstract

The invention provides a time-of-flight depth camera and a single-frequency modulation-demodulation noise-reducing distance measuring method. The time-of-flight depth camera comprises a transmitting module, an acquisition module and a processing circuit, wherein the transmitting module comprises a light source which is used for transmitting a pulse beam to an object to be measured; the acquisitionmodule comprises an image sensor composed of at least one pixel, each pixel comprises at least three taps, and the taps are sued for acquiring a charge signal generated by a reflected pulse beam which is reflected by means of the object to be measured and/or a charge signal of background light; and the processing circuit is used for controlling the at least three taps to acquire the charge signals alternatively between at least three frame periods of a macro period, and receiving data of the charge signals to calculate a time of flight of the pulse beam and/or a distance of the object to be measured. The expansion of the measurement distance is no longer limited by the pulse width, and the fixed-pattern noise caused by mismatch between the taps or read-out circuits due to process manufacturing errors and the like is reduced or eliminated by adopting a tap alternative acquisition method.

Description

technical field [0001] The invention relates to the technical field of optical measurement, in particular to a time-of-flight depth camera and a noise-reducing distance measurement method for single-frequency modulation. Background technique [0002] The full name of ToF is Time-of-Flight, that is, time of flight. The ToF ranging method is a technology that achieves precise ranging by measuring the round-trip flight time of light pulses between the transmitting / receiving device and the target object. In ToF technology, the technology of directly measuring the time of flight of light is called dToF (direct-TOF); the emitted optical signal is periodically modulated, and the phase delay of the reflected optical signal relative to the emitted optical signal is measured, and then by The measurement technology for calculating the time of flight by phase delay is called iToF (Indirect-TOF) technology. According to different modulation and demodulation methods, it can be divided in...

AI Technical Summary

Problems solved by technology

[0003] At present, CW-iToF technology is mainly used in measurement systems based on two-tap sensors. The core measurement algorithm is a four-phase modulation and demodulation method, which requires at least two exposures (in order to ensure measurement accuracy, four exposures are usually required ) to complete the acquisition of four phase data and output a frame of depth image, so it is difficult to obtain a higher frame rate

PM-iToF modulation technology is mainly used in four-tap pixel sensors (three taps are used for signal acquisition and output, and one tap is used to release invalid electrons). The measurement distance o

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