阅读说明：本技术 直接飞行时间dtof传感器的感测控制装置和方法 (Sensing control device and method of direct time-of-flight (DTOF) sensor ) 是由 史斌 杨骁� 刘昆 李强 于 2021-09-06 设计创作，主要内容包括：本发明提供了一种直接飞行时间DTOF传感器的感测控制装置和方法,包括：SPAD阵列,包括N种不同的感光度的SPAD像素组,用于检测光子信息并产生脉冲信号；开关装置,被配置为连接在所述SPAD阵列和读出电路之间,用于控制所述SPAD像素组选通或关闭；读出电路,包括用于记录SPAD像素组的击穿时刻信息的TDC,以及用于存储光子信息直方图的SRAM；控制电路,被配置为根据光子信息直方图选择像素组,并且对其数据进行处理。(The invention provides a sensing control device and a method of a direct time-of-flight (DTOF) sensor, which comprise the following steps: the SPAD array comprises SPAD pixel groups with N different sensitivities and is used for detecting photon information and generating pulse signals; the switching device is configured to be connected between the SPAD array and the readout circuit and used for controlling the SPAD pixel group to be switched on or switched off; the reading circuit comprises a TDC for recording the breakdown time information of the SPAD pixel group and an SRAM for storing a photon information histogram; a control circuit configured to select a pixel group according to the photon information histogram and process data thereof.)

1. A sensing control device of a direct time-of-flight, DTOF, sensor, comprising:

the SPAD array comprises SPAD pixel groups with N different sensitivities, wherein N is a natural number which is greater than or equal to 2;

a switching device configured to be connected between the SPAD array and a readout circuit for controlling the SPAD pixel groups to be turned on or off;

the readout circuit comprises a TDC and an SRAM, wherein the TDC is used for recording breakdown moment information of the SPAD pixel group, and the SRAM is used for storing a photon information histogram;

a control circuit configured to select a SPAD pixel group according to the photon information histogram and perform signal processing on data thereof.

2. The sensing control device of the DTOF sensor of claim 1, wherein the SPAD pixel groups comprise SPAD pixel groups having high sensitivity and SPAD pixel groups having low sensitivity.

3. The sensing control device of the DTOF sensor of claim 2, wherein the low sensitivity is 1/10 with high sensitivity.

4. The sensing control device of the DTOF sensor of claim 1, wherein the SPAD pixel group comprises 1 or a plurality of SPAD pixels of the same sensitivity connected in parallel.

5. The sensing control device of the DTOF sensor of claim 1, wherein the switching device is configured to gate a first set of SPAD pixel groups for a first period of time and to gate off other SPAD pixel groups than the first set of SPAD pixel groups; gating the second group of SPAD pixel groups in the second time period and turning off other SPAD pixel groups except the second group of SPAD pixel groups; the nth group of SPAD pixel groups are gated on for the nth period of time, and SPAD pixel groups other than the nth group of SPAD pixel groups are turned off.

6. The sensing control device of the DTOF sensor of claim 1, wherein the TDCs are configured to read signals of a first set of SPAD pixel groups for a first time period, read signals of a second set of SPAD pixel groups for a second time period and read signals of an nth set of SPAD pixel groups for an nth time period.

7. The sensing control device of the DTOF sensor of claim 1, wherein the SRAM stores a photon information histogram for SPAD breakdown time information.

8. The sensing control device of the DTOF sensor of claim 1, wherein the control circuitry comprises a controller; the controller is configured to:

reading photon information histograms of a first group of SPAD pixel groups in a first time period, reading photon information histograms of a second group of SPAD pixel groups in a second time period, and reading photon information histograms of an Nth group of SPAD pixel groups in an Nth time period;

the signal intensities associated with the acquired first to nth sets of photon information histograms are compared, a SPAD pixel group is selected according to the comparison result, and the data thereof is subjected to signal processing.

9. A method of controlling a sensing control device of a DTOF sensor comprising a SPAD array, a switching device, a readout circuit, and a control circuit, the method comprising:

the SPAD pixel groups with different light sensitivity in the SPAD array are switched on and off through the switching device;

recording breakdown time information of the gated SPAD pixel group and storing a photon information histogram through a reading circuit;

and comparing the signal intensity related to the photon information histogram through a control circuit, selecting an SPAD pixel group according to the comparison result, and carrying out signal processing on the data.

10. The method of claim 9, wherein gating on and off SPAD pixel groups in the SPAD array by the switching device comprises:

gating a first group of SPAD pixel groups in the SPAD array in a first time period through a switching device, and turning off other SPAD pixel groups except the first group of SPAD pixel groups; gating a second group of SPAD pixel groups in the SPAD array in a second time period, and turning off other SPAD pixel groups except the second group of SPAD pixel groups; the nth group of SPAD pixel groups in the SPAD array are strobed in the nth period of time, and SPAD pixel groups other than the nth group of SPAD pixel groups are turned off.

11. The method of claim 9, wherein recording the breakdown time information for the SPAD pixel groups and storing the photon information histogram with the readout circuitry comprises:

the signals of the first group of SPAD pixel groups are read in a first time period and photon information histograms of the first group of SPAD pixel groups are generated, the signals of the second group of SPAD pixel groups are read in a second time period and photon information histograms of the second group of SPAD pixel groups are generated, and the signals of the nth group of SPAD pixel groups are read in an nth time period and photon information histograms of the nth group of SPAD pixel groups are generated.

12. The method of claim 9, wherein comparing, by the controller, signal strengths associated with the photon information histograms comprises:

comparing, by the controller, signal intensities associated with the photon information histograms of the first set of SPAD pixel groups, the photon information histograms of the second set of SPAD pixel groups, and the photon information histograms of the nth set of SPAD pixel groups.

13. The method according to claim 9, wherein the SPAD pixel groups include a SPAD pixel group having high sensitivity and a SPAD pixel group having low sensitivity.

14. The method of claim 13, wherein said low sensitivity is high sensitivity 1/10.

Technical Field

The present invention relates to the field of 3D depth sensing, and in particular, to a sensing control apparatus and method of a Direct Time of Flight (DTOF) sensor.

Background

With the technical development of laser radar, Time of flight (TOF) has received increasing attention, and the TOF principle is to obtain the distance to an object to be measured by continuously emitting light pulses to the object to be measured, receiving the light reflected from the object to be measured with a sensor, and detecting the Time of flight of the light pulses.

The DTOF ranging method is a ranging method developed based on TOF, and receives more and more attention by virtue of its advantages in use. The core device for realizing the DTOF ranging mode is a Photon-triggered counting type detector of a Single Photon Avalanche Diode (SPAD) type.

A DTOF sensor is an active optical sensor comprising at least two main parts, a transmitting device and a receiving device. The transmitting device transmits short pulse laser to irradiate the object to be measured, and part of the laser is reflected and then received by the receiving device. Because of the existence of the synchronous signal between the transmitting device and the receiving device, the control circuit can record the time t of the laser flying back and forth in the air, and the distance d of the measured object is 1/2C t by knowing the light speed C.

In the short-distance measurement, due to strong reflected light, the DTOF sensor may be saturated to cause no distance measurement, or a stacking effect may be generated, so that a recorded signal (in the form of a histogram) is distorted, and the distance measurement accuracy is reduced.

In view of the above technical problems, there is a need for an apparatus and a method for enhancing a light intensity sensing range of a TOF 3D sensing system to provide a reliable solution, so as to achieve accurate ranging of the TOF 3D sensing system in a ranging scene with strong light intensity at a short distance.

Disclosure of Invention

Solves the technical problem

In the short-distance measurement, due to strong reflected light, the DTOF sensor may be saturated to cause no distance measurement, or a stacking effect may be generated, so that a recorded signal (in the form of a histogram) is distorted, and the distance measurement accuracy is reduced.

Technical scheme

In order to solve the above problems, the present invention provides a sensing control apparatus and method of a DTOF sensor.

The invention provides a sensing control device of a DTOF sensor, comprising: the SPAD array comprises SPAD pixel groups with N different sensitivities, wherein N is a natural number which is greater than or equal to 2; a switching device configured to be connected between the SPAD array and a readout circuit for controlling the SPAD pixel groups to be turned on or off; the readout circuit comprises a TDC and an SRAM, wherein the TDC is used for recording breakdown moment information of the SPAD pixel group, and the SRAM is used for storing a photon information histogram; a control circuit configured to select a group of pixels from the photon information histogram and process data thereof.

The invention provides a sensing control device of a DTOF sensor, wherein the SPAD pixel group comprises a SPAD pixel group with high sensitivity and a SPAD pixel group with low sensitivity.

The invention provides a sensing control device of a DTOF sensor, wherein the low sensitivity is 1/10 with high sensitivity.

The invention provides a sensing control device of a DTOF sensor, wherein the SPAD pixel group comprises 1 or a plurality of SPAD pixels with the same sensitivity connected in parallel.

The invention provides a sensing control device of a DTOF sensor, wherein a switch device is configured to gate a first group of SPAD pixel groups in a first time period and close other SPAD pixel groups except the first group of SPAD pixel groups; gating the second group of SPAD pixel groups in the second time period and turning off other SPAD pixel groups except the second group of SPAD pixel groups; the nth group of SPAD pixel groups are gated on for the nth period of time, and SPAD pixel groups other than the nth group of SPAD pixel groups are turned off.

The invention provides a sensing control device of a DTOF sensor, wherein the TDC is configured to read signals of a first group of SPAD pixel groups in a first time period, read signals of a second group of SPAD pixel groups in a second time period and read signals of an Nth group of SPAD pixel groups in an Nth time period.

The invention provides a sensing control device of a DTOF sensor, wherein the SRAM stores a photon information histogram related to SPAD breakdown moment information.

The invention provides a sensing control device of a DTOF sensor, wherein a control circuit comprises a controller; the controller is configured to: reading photon information histograms of a first group of SPAD pixel groups in a first time period, reading photon information histograms of a second group of SPAD pixel groups in a second time period, and reading photon information histograms of an Nth group of SPAD pixel groups in an Nth time period; the signal intensities associated with the acquired first to nth sets of photon information histograms are compared, a SPAD pixel group is selected according to the comparison result, and the data thereof is subjected to signal processing.

The invention also provides a method of controlling a sensing control device of a DTOF sensor, the sensing control device of the DTOF sensor comprising a SPAD array, a switching device, a readout circuit, and a control circuit, the method comprising: the SPAD pixel groups in the SPAD array are switched on and off through the switching devices; recording breakdown time information of the gated SPAD pixel group and storing a photon information histogram through a reading circuit; and comparing the signal intensity related to the photon information histogram through a control circuit, selecting an SPAD pixel group according to the comparison result, and carrying out signal processing on the data.

The invention also provides a method of controlling a sensing control device of a DTOF sensor, wherein gating on and off SPAD pixel groups in a SPAD array by a switching device comprises: gating a first group of SPAD pixel groups in the SPAD array in a first time period through a switching device, and turning off other SPAD pixel groups except the first group of SPAD pixel groups; gating a second group of SPAD pixel groups in the SPAD array in a second time period, and turning off other SPAD pixel groups except the second group of SPAD pixel groups; the nth group of SPAD pixel groups in the SPAD array are strobed in the nth period of time, and SPAD pixel groups other than the nth group of SPAD pixel groups are turned off.

The present invention also provides a method of controlling a sensing control device of a DTOF sensor, wherein recording breakdown time information of SPAD pixel groups and storing a photon information histogram by a readout circuit comprises: the signals of the first group of SPAD pixel groups are read in a first time period and photon information histograms of the first group of SPAD pixel groups are generated, the signals of the second group of SPAD pixel groups are read in a second time period and photon information histograms of the second group of SPAD pixel groups are generated, and the signals of the nth group of SPAD pixel groups are read in an nth time period and photon information histograms of the nth group of SPAD pixel groups are generated.

The present invention also provides a method of controlling a sensing control device of a DTOF sensor, wherein comparing, by a controller, signal strengths associated with a histogram of photon information comprises: comparing, by the controller, signal intensities associated with the photon information histograms of the first set of SPAD pixel groups, the photon information histograms of the second set of SPAD pixel groups, and the photon information histograms of the nth set of SPAD pixel groups.

The invention also provides a method for controlling the sensing control device of the DTOF sensor, wherein the SPAD pixel group comprises a SPAD pixel group with high sensitivity and a SPAD pixel group with low sensitivity.

The invention also provides a method for controlling the sensing control device of the DTOF sensor, wherein the low sensitivity is 1/10 with high sensitivity.

Advantageous effects

Compared with the prior art, the invention provides a sensing control device and a sensing control method of a DTOF sensor, which have the following beneficial effects: (1) due to the existence of the low-sensitivity SPAD pixels, signal saturation and accumulation effects caused by too strong reflected light during short-distance ranging are avoided, and the short-distance ranging precision is effectively improved; (2) matched TDC and SRAM resources are multiplexed in a time-sharing mode, so that the resources of the TDC and the SRAM are saved the most, the chip area is saved the most, and the cost is low. (3) The DTOF sensor can accommodate a wide range of strong and weak optical signals.

Drawings

Fig. 1 is a schematic diagram of the connections and relationships of the various key components of a sensing control device of a DTOF sensor according to an embodiment of the invention;

FIG. 2 is a schematic diagram of a histogram according to an embodiment of the invention; and

FIG. 3 is a schematic diagram of the timing of the operation of a SPAD array according to an embodiment of the present invention;

Detailed Description

Before proceeding with the following detailed description, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms "couple," "connect," and derivatives thereof refer to any direct or indirect communication or connection between two or more elements, whether or not those elements are in physical contact with one another. The terms "transmit," "receive," and "communicate," as well as derivatives thereof, encompass both direct and indirect communication. The terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation. The term "or" is inclusive, meaning and/or. The phrase "associated with … …" and derivatives thereof means including, included within … …, interconnected, contained within … …, connected or connected with … …, coupled or coupled with … …, in communication with … …, mated, interwoven, juxtaposed, proximate, bound or bound with … …, having an attribute, having a relationship or having a relationship with … …, and the like. The term "controller" refers to any device, system, or part thereof that controls at least one operation. Such a controller may be implemented in hardware, or a combination of hardware and software and/or firmware. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. The phrase "at least one of, when used with a list of items, means that a different combination of one or more of the listed items can be used and only one item in the list may be required. For example, "at least one of A, B, C" includes any one of the following combinations: A. b, C, A and B, A and C, B and C, A and B and C.

Definitions for other specific words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

In this patent document, the application combination of modules and the division levels of sub-modules are only used for illustration, and the application combination of modules and the division levels of sub-modules may have different manners without departing from the scope of the present disclosure.

Fig. 1 is a schematic diagram of the connection and relationship of the various key components of the sensing control device of the DTOF sensor according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a histogram with time on the abscissa and counts on the ordinate according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of the operation timing of the SPAD array according to an embodiment of the invention.

The sensing control device of the DTOF sensor comprises a SPAD array, a switching device, a readout circuit and a control circuit.

The SPAD array comprises SPAD pixel groups with N different sensitivities, wherein N is a natural number which is greater than or equal to 2. The SPAD array is used to detect photon information and generate pulse signals.

The SPAD pixel group includes a SPAD pixel group having high sensitivity and a SPAD pixel group having low sensitivity. According to an embodiment of the present invention, the SPAD pixel group having high sensitivity includes pixels having sensitivity greater than a first sensitivity threshold, and the SPAD pixel group having low sensitivity includes pixels having sensitivity lower than a second sensitivity threshold. Among them, the low sensitivity may be 1/8, 1/10 or 1/100 of high sensitivity, of which 1/10 is preferable, and this specific value is exemplary and does not limit the present invention to the above embodiment.

The SPAD pixel group includes: 1 or a plurality of SPAD pixels of the same sensitivity connected in parallel.

The switching device is configured to be connected between the SPAD array and the readout circuitry for controlling the SPAD pixel groups to be turned on or off. Specifically, the switching device is configured to gate a first group of SPAD pixel groups for a first period of time and to gate off SPAD pixel groups other than the first group of SPAD pixel groups; gating the second group of SPAD pixel groups in the second time period and turning off other SPAD pixel groups except the second group of SPAD pixel groups; the nth group of SPAD pixel groups are gated on for the nth period of time, and SPAD pixel groups other than the nth group of SPAD pixel groups are turned off.

The readout circuit includes a Time To Digital Converter (TDC) 110 and a Static Random-Access Memory (SRAM) 120.

The TDC 110 is a high-precision clock for recording SPAD breakdown time information, i.e., the time when the SPAD array is broken down and generates a pulse signal. The TDC 110 is configured to read signals of a first group of SPAD pixel groups in a first period, read signals of a second group of SPAD pixel groups in a second period, and read signals of an nth group of SPAD pixel groups in an nth period.

The SRAM 120 stores SPAD breakdown time information in the form of a histogram for storing a photon information histogram, i.e., a photon information histogram storing information on SPAD breakdown time. The form of the histogram may be that of the histogram shown in fig. 2. The TDC 110 is connected to the SRAM 120.

The control circuitry is configured to recall and process data from the photon information histogram. The control circuit includes a controller 130, the controller 130 configured to: the photon information histogram of the SPAD breakdown time information stored in the SRAM 120 is called and data is processed. The controller 130 reads the photon information histogram of the first group of SPAD pixel groups during the first time period, reads the photon information histogram of the second group of SPAD pixel groups during the second time period, and reads the photon information histogram of the nth group of SPAD pixel groups during the nth time period. The signal intensities associated with the acquired first to nth sets of photon information histograms are compared, a SPAD pixel group is selected according to the comparison result, and the data thereof is subjected to signal processing. The SRAM 120 is connected to a controller 130.

According to the sensing control device of the DTOF sensor, the method of controlling the sensing control device of the DTOF sensor includes:

the SPAD pixel groups in the SPAD array are switched on and off through the switching devices; recording breakdown time information of the gated SPAD pixel group and storing a photon information histogram through a reading circuit; and comparing the signal intensity related to the photon information histogram through a control circuit, selecting an SPAD pixel group according to the comparison result, and carrying out signal processing on the data. Wherein the SPAD pixel group includes a SPAD pixel group having a high sensitivity and a SPAD pixel group having a low sensitivity of 1/8, 1/10 or 1/100, wherein 1/10 is preferred, and the specific numerical values are exemplary and do not limit the present invention to any particular embodiment.

Specifically, the switching device gates a first group of SPAD pixel groups in the SPAD array in a first time period and turns off other SPAD pixel groups except the first group of SPAD pixel groups; gating a second group of SPAD pixel groups in the SPAD array in a second time period, and turning off other SPAD pixel groups except the second group of SPAD pixel groups; the nth group of SPAD pixel groups in the SPAD array are strobed in the nth period of time, and SPAD pixel groups other than the nth group of SPAD pixel groups are turned off.

The TDC 110 and the SRAM 120 read signals of the first group of SPAD pixel groups in a first time period and generate a photon information histogram of the first group of SPAD pixel groups, and store it into the SRAM 120; reading signals of the second group of SPAD pixel groups in a second time period, generating a photon information histogram of the second group of SPAD pixel groups, and storing the photon information histogram into the SRAM 120; and reads the signals of the nth group of SPAD pixel groups in the nth period of time and generates a photon information histogram of the nth group of SPAD pixel groups, which is stored in the SRAM 120.

The controller 130 reads the photon information histogram of the first group of SPAD pixel groups, the photon information histogram of the second group of SPAD pixel groups and the photon information histogram of the nth group of SPAD pixel groups from the SRAM 120; comparing signal intensities associated with the photon information histograms of the first, second and nth sets of SPAD pixel groups; according to the comparison result, selecting an SPAD pixel group with moderate signal intensity, and carrying out signal processing on the data of the SPAD pixel group; and (5) completing the ranging of one frame, repeating the process and continuously working.

As shown in fig. 1 and 2, a sensing control device of a DTOF sensor according to an embodiment of the present disclosure when N is 2 includes a SPAD array, a switching device, a readout circuit, and a control circuit.

As shown in fig. 1, the SPAD array may include SPAD pixel groups at the sensitivities SPAD 1 and SPAD 2. The SPAD array is used to detect photon information and generate pulse signals. SPAD 1 has a higher sensitivity, SPAD 2 has a lower sensitivity, SPAD 2 has a sensitivity of 1/10 of the sensitivity of SPAD 1, which specific values are exemplary and do not limit the invention to any particular embodiment.

The SPAD 1 pixel group includes 1 or a plurality of SPAD 1 pixels connected in parallel. The SPAD 2 pixel group includes 1 or a plurality of SPAD 2 pixels connected in parallel.

The switching device is configured to be connected between the SPAD array and the readout circuitry for controlling the SPAD 1 and SPAD 2 pixel groups to be turned on or off. Specifically, the switching device is configured to gate the SPAD 1 pixel group and turn off the SPAD 1 pixel groups other than the SPAD 1 pixel group in the T1 period; the SPAD 2 pixel group is strobed for a period of T2, and SPAD pixel groups other than the SPAD 2 pixel group are turned off.

The readout circuit includes a TDC 110 and an SRAM 120.

The TDC 110 is a high-precision clock for recording SPAD breakdown time information, i.e., the time when the SPAD array is broken down and generates a pulse signal. The TDC 110 is configured to read the signals of the SPAD 1 pixel group in the T1 period and read the signals of the SPAD 2 pixel group in the T2 period.

The SRAM 120 stores SPAD breakdown time information in the form of a histogram for storing a photon information histogram, i.e., a photon information histogram storing information on SPAD breakdown time. The form of the histogram may be that of the histogram shown in fig. 2. The TDC 110 is connected to the SRAM 120.

The control circuitry is configured to recall and process data from the photon information histogram. The control circuit includes a controller 130, the controller 130 configured to: the photon information histogram of the SPAD breakdown time information stored in the SRAM 120 is called and data is processed. The controller 130 reads the photon information histogram of the SPAD 1 pixel group during the T1 period and reads the photon information histogram of the SPAD 2 pixel group during the T2 period. And comparing the acquired photon information histograms of the SPAD 1 pixel group and the SPAD 2 pixel group, selecting the SPAD pixel group according to the comparison result, and performing signal processing on the data. The SRAM 120 is connected to a controller 130.

As shown in fig. 3, a sensing control method of a DTOF sensor according to an embodiment of the present disclosure when N-2 includes:

the SPAD 1 pixel group and the SPAD 2 pixel group in the SPAD array are switched on and off through the switching device; recording breakdown time information of the gated SPAD pixel group and storing a photon information histogram through a reading circuit; and comparing the signal intensity related to the photon information histogram through a control circuit, selecting an SPAD pixel group according to the comparison result, and carrying out signal processing on the data. Wherein the SPAD pixel group includes a SPAD 1 pixel group having a high sensitivity and a SPAD 2 pixel group having a low sensitivity, wherein the sensitivity of SPAD 2 is 1/10 of the sensitivity of SPAD 1, and the specific numerical value is exemplary and does not limit the present invention to any particular embodiment.

Specifically, the switching device gates the SPAD 1 pixel group and turns off the SPAD 2 pixel group during the T1 time period; the SPAD 2 pixel group is gated on and the SPAD 1 pixel group is turned off for a period of T2.

The TDC 110 and the SRAM 120 read the signals of the SPAD 1 pixel group in the T1 time period and generate a photon information histogram 1 of the SPAD 1 pixel group, store it into the SRAM 120; the signals of the SPAD 2 pixel group are read in the T2 time period and the photon information histogram 2 of the SPAD 2 pixel group is generated and stored into the SRAM 120.

The controller 130 reads the photon information histogram 1 and the photon information histogram 2 from the SRAM 120; comparing the signal intensity of the photon information histogram 1 and the photon information histogram 2; according to the comparison result, selecting an SPAD pixel group with moderate signal intensity, and carrying out signal processing on the data of the SPAD pixel group; and (5) completing the ranging of one frame, repeating the process and continuously working.

Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to embrace such alterations and modifications as fall within the scope of the appended claims.

None of the description in this specification should be read as implying that any particular element, step, or function is an essential element which must be included in the claim scope. The scope of patented subject matter is defined only by the claims.