Distance sensor and 3D image sensor

Abstract

The invention provides a distance sensor and a 3D image sensor. The distance sensor comprises a photon detection circuit, a first capacitive device and a charge control module. The photon detection circuit is responsive to the reflected photon to generate a charge stop signal, and the reflected photon is obtained by reflecting a photon which is emitted by a light source by a target object. The charge control module is used for controlling the preset charge current to charge the first capacitive device in response to the charge start signal and controlling the charge current to stop charging the first capacitive device in response to the charge stop signal, and the charge start signal is generated when the light source emits photons. The amount of change in the voltage across the first capacitive device in the time window is used to determine the distance between the target object and the distance sensor, the time window is defined by the charge start signal and the charge stop signal. With the adoption of the technical scheme, the measurement precision of the 3D image sensor based on the photon detection technique can be effectively improved.

Description

technical field [0001] The invention relates to the technical field of 3D image sensors, in particular to a distance sensor and a 3D image sensor. Background technique [0002] Light has wave and particle nature. According to the particle nature of light, light is composed of a large number of photons, and the energy of photons is determined by the frequency of light. Since the energy of a single photon in the visible light band is extremely low, in order to be able to detect low-energy photons, a special photodetection device, that is, a single-photon detector, is required. There are two main types of single photon detectors: photomultiplier tubes and single photon avalanche diodes (Single Photon Avalanche Diode, referred to as SPAD). Among them, SPAD based on semiconductor technology has the advantages of high measurement efficiency in the infrared communication band, low power consumption, small size, large operating spectrum range, and low operating voltage. It is wide...

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Problems solved by technology

[0004] Because the speed of light is very fast, the measurement accuracy of the 3D image sensor in the prior art depends heavily on the phase noise of the high-speed clock and the operating frequency of the high-speed counter. Taking its operating frequency of 10GHz as an example, the maximum time resolution that can be achieved at present It is about 100pS, which is converted into a physical size of about 15mm. For some high-precision applications, such as face recognition, the ranging resolution of 15mm cannot meet the demand at all, and the high-speed counter 40 needs to work at a high frequency of 10GHZ. The requirements for the circuit are also very high

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