CN219105159U - Time-of-flight ranging sensor including histogram state monitoring device - Google Patents
Time-of-flight ranging sensor including histogram state monitoring device Download PDFInfo
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- CN219105159U CN219105159U CN202122157065.5U CN202122157065U CN219105159U CN 219105159 U CN219105159 U CN 219105159U CN 202122157065 U CN202122157065 U CN 202122157065U CN 219105159 U CN219105159 U CN 219105159U
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Abstract
The utility model proposes a time-of-flight ranging sensor comprising a histogram state monitoring device, comprising: a single photon avalanche detector SPAD pixel array configured to detect incidence of photons and output a pulse signal; a time-to-digital converter TDC configured to record information about the time instant of a pulse signal generated by the SPAD being broken down; a histogram generation means configured to generate histogram information based on the information recorded by the TDC; and a histogram state monitoring device configured to monitor the state of the histogram in real time, and stop lighting according to the monitoring result, output the histogram.
Description
Technical Field
The present disclosure relates to the field of time-of-flight ranging, and more particularly, to a time-of-flight ranging sensor including a histogram state monitoring device.
Background
Time-of-Flight (Time-of-Flight) technology is considered as one of the most optimal sensor technologies, and due to its advent, a trend of loading a 3D camera in a mobile device applied in various application scenarios is caused, and as the technology of the internet of things and the technology of semiconductors are developed, the application field thereof will continue to be expanded, and in addition, corresponding research on improving the performance thereof is also being conducted.
Existing time-of-flight sensors determine the distance between the time-of-flight sensor and the object by shining light on the object and detecting the incidence of photons, and recording the time at which the photons were detected.
Disclosure of Invention
Technical problem
The number of times of lighting of the flight time sensor is fixed, and the histogram memory is easily saturated under the condition of over strong signal or background light, so that the calculated distance information generates errors; when the optical conditions are good, the histogram can be made to reach a very high signal to noise ratio quickly, so the subsequent polishing does not help to improve the distance accuracy, but consumes additional energy.
Solution to the problem
According to an aspect of the present disclosure there is provided a time-of-flight ranging sensor comprising histogram state monitoring means, comprising: a single photon avalanche detector SPAD pixel array configured to detect incidence of photons and output a pulse signal; a time-to-digital converter TDC configured to record information about the time instant of a pulse signal generated by the SPAD being broken down; a histogram generation means configured to generate histogram information based on the information recorded by the TDC; and a histogram state monitoring device configured to monitor the state of the histogram in real time, and stop lighting according to the monitoring result, output the histogram.
According to an aspect of the present disclosure, there is provided a time-of-flight ranging sensor including a histogram state monitoring means, wherein the histogram generating means is configured to take a numerical value recorded by a TDC as an address value of a histogram memory, read data stored at a corresponding address and add 1, and write the numerical value after the addition back to the corresponding address to generate histogram information.
According to an aspect of the present disclosure there is provided a time-of-flight ranging sensor comprising a histogram state monitoring apparatus, wherein the histogram state monitoring apparatus is configured to comprise a first register, a second register and a comparator; wherein the first register stores a preset first threshold value, and the second register stores a value of a histogram memory of an address corresponding to a numerical value recorded by a current TDC; and the comparator compares the values of the first register and the second register, and stops lighting when the value of the second register is greater than a first threshold value, and outputs a histogram.
According to an aspect of the present disclosure, a time-of-flight ranging sensor is presented, comprising a histogram state monitoring means, wherein the histogram state monitoring means is configured to comprise a counter configured to count the number of hits and to activate the histogram state monitoring means when the count value reaches a second threshold.
According to an aspect of the present disclosure, there is provided a time-of-flight ranging sensor including a histogram state monitoring apparatus, wherein the histogram state monitoring apparatus is configured to include a third register configured to store a value of a histogram memory of an address corresponding to a numerical value of a current TDC record, and a comparator to compare the value of the third register with a third threshold value calculated from a count value of a counter, and stop lighting when the value of the third register is greater than the third threshold value, output a histogram.
According to an aspect of the present disclosure, a time-of-flight ranging sensor is presented, comprising a histogram state monitoring means, wherein the histogram state monitoring means is configured to comprise a fourth register storing a value corresponding to a first address value in a histogram memory, wherein the fourth register stores that the value corresponding to the first address value in the histogram memory corresponds to the intensity of the backlight when the TDC timing start instant is earlier than the lighting instant.
According to an aspect of the present disclosure, a time-of-flight ranging sensor is presented comprising a histogram state monitoring apparatus, wherein the intensity of the lighting is increased when the value stored by the fourth register is greater than a fourth threshold value, and wherein the intensity of the lighting is decreased when the value stored by the fourth register is less than a fifth threshold value.
According to an aspect of the present disclosure, there is provided a time-of-flight ranging sensor including a histogram state-monitoring apparatus, wherein the histogram state-monitoring apparatus is configured to include a fifth register storing a maximum value of values of a histogram memory corresponding to an address corresponding to a numerical value of a TDC record, and a processor calculating a signal-to-noise ratio from the values in the fourth register and the values stored in the fifth register and address values corresponding to the values stored in the fifth register.
According to an aspect of the present disclosure, there is provided a time-of-flight ranging sensor including a histogram state monitoring apparatus, wherein adjusting lighting according to a signal-to-noise ratio includes: and stopping polishing when the signal-to-noise ratio is higher than a preset sixth threshold value, and outputting a histogram.
According to an aspect of the present disclosure, a method of controlling a time-of-flight ranging sensor comprising a histogram state monitoring apparatus is presented, comprising the steps of: detecting incidence of photons and outputting pulse signals; recording information related to the timing of outputting the pulse signal; generating histogram information based on information related to the time instants at which the pulse signals are output; and monitoring the state of the histogram in real time, stopping polishing according to the monitoring result, and outputting the histogram.
The disclosed advantageous effects
The time-of-flight ranging sensor monitors the state of the histogram in real time through the histogram state monitoring device and judges whether the lighting needs to be stopped or not, so that the exposure time is shortened, and the overall power consumption is reduced; furthermore, the time-of-flight ranging sensor of the present disclosure is also capable of characterizing the optical conditions of the current test environment, thereby dynamically controlling the system.
Drawings
The foregoing and other aspects, features, and advantages of certain embodiments of the disclosure will become more apparent from the following description, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a time-of-flight ranging sensor according to an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of a time-of-flight ranging sensor according to another embodiment of the present disclosure;
FIG. 3 is a schematic diagram of a time-of-flight ranging sensor according to another embodiment of the present disclosure;
FIG. 4 is a schematic diagram of a time-of-flight ranging sensor according to another embodiment of the present disclosure;
fig. 5 is a flowchart of a time-of-flight ranging method according to an embodiment of the present disclosure.
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 "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 its derivatives are intended to include, be included in, interconnect with, contain within … …, connect or connect with … …, couple or couple with … …, communicate with … …, mate, interleave, juxtapose, approximate, bind or bind with … …, have attributes, have relationships or have relationships with … …, etc. The term "controller" refers to any device, system, or portion 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," when used with a list of items, means that different combinations of one or more of the listed items may be used, and that 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 combinations of transform blocks and the division levels of sub-transform blocks are for illustration only, and the application combinations of transform blocks and the division levels of sub-transform blocks may have different manners without departing from the scope of the present disclosure.
Figures 1 through 4, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will appreciate that the principles of the present disclosure may be implemented in any suitably arranged system or device.
Fig. 1 illustrates a time-of-flight ranging sensor according to an embodiment of the present disclosure, comprising: SPAD (Single Photon Avalanche Detector ) pixel array 100 configured to detect incidence of photons and output a pulse signal; a TDC (Time to Digital Convertor, time-to-digital converter) 300 configured to record, as a high-precision clock, information about the timing of a pulse signal generated by the SPAD being broken down; a histogram generation means 400 configured to generate histogram information based on the information recorded by the TDC 300; and a histogram state monitoring device 500 configured to monitor the state of the histogram in real time, and stop lighting according to the monitoring result, output the histogram.
Specifically, the pulse signals output from the SPAD pixel array 100 are connected together by a gate circuit 200 such as an OR gate OR an XOR gate, and then sent to the TDC 300.
Fig. 2 illustrates a time-of-flight ranging sensor according to another embodiment of the present disclosure, wherein a description of the same parts as those in fig. 1 will be omitted for more clarity of description of the drawings. Referring to fig. 2, the histogram generating apparatus 400 is configured to take the numerical value recorded by the TDC 300 as an address value of the histogram memory 510, read the data stored in the corresponding address and add 1, and write the numerical value after the addition back to the corresponding address to generate histogram information.
The histogram state that monitors apparatus 500 reads the value stored in histogram memory 510. Referring to fig. 2, the histogram state monitoring apparatus 500 is configured to include a first register 521, a second register 522, and a comparator 531.
Wherein the first register 521 stores a preset first threshold value, and the second register 522 stores a value of the histogram memory 510 of an address corresponding to the numerical value of the current TDC record; and the comparator 531 compares the values of the first register 521 and the second register 522, and based on the comparison result, issues an instruction to stop lighting and start processing the histogram when the value of the second register 522 is greater than the value of the first register 521; and when the value of the second register 522 is smaller than the value of the first register 521, the above-described process is repeated.
Fig. 3 illustrates a time-of-flight ranging sensor according to another embodiment of the present disclosure, wherein a description of the same parts as those in fig. 1 will be omitted for more clarity of description of the drawings. Referring to fig. 3, the histogram state monitoring apparatus 500 is configured to include a counter 540, the counter 540 being configured to count the number of times of lighting, and when the count value reaches a second threshold value, the histogram state monitoring apparatus 500 is started.
Further, the histogram state that monitors apparatus 500 is configured to include a third register 523 and a comparator 532, the third register 523 is configured to store the value of the histogram memory 510 of the address corresponding to the value of the current TDC record, and the comparator 532 compares the value of the third register 523 with a third threshold value calculated from the count value of the counter 540, and, according to the comparison result, when the value of the third register 523 is greater than the third threshold value calculated from the count value of the counter 540, issues an instruction to stop lighting, and starts processing the histogram; and when the value of the third register 523 is smaller than the third threshold value, the above-described process is repeated.
Fig. 4 illustrates a time-of-flight ranging sensor according to another embodiment of the present disclosure, wherein a description of the same parts as those in fig. 1 will be omitted for more clarity of description of the drawings. Referring to fig. 4, the histogram state monitoring apparatus 500 is configured to include a fourth register 524, a fifth register 525, and a processor 550, the fourth register 524 storing data corresponding to a first address value in the histogram memory 510, the fifth register 525 storing a largest value among values in the histogram memory 510 corresponding to an address corresponding to a value recorded by a TDC, and the processor 550 calculating a signal-to-noise ratio from the value in the fourth register 524 and the value stored in the fifth register 525 and the address value corresponding to the value stored in the fifth register 525.
Specifically, when the timing start time of the TDC 300 is earlier than the lighting time, the first address value corresponds to a photon sensed only from the background light, and thus the value corresponding to the address value may represent the intensity of the background light.
For example, at this time, the number of photons of the background light is N, the time width corresponding to the first address value is T, and the probability of the SPAD pixel breakdown is:
1-e -N×T×PDE equation 1
After M measurements, the expected value of the data corresponding to the first address value is:
M×(1-e -N×T×PDE ) Equation 2
Thus, the data corresponding to the first address value may characterize the intensity of the background light.
Further, the data corresponding to the first address value "0" is represented by bin [0], and the data corresponding to the maximum value in the histogram memory unit 510 at the address "k" is represented by bin [ k ], the signal-to-noise ratio is obtained by the following calculation formula:
where f (k) is a function related to k.
According to an embodiment of the present utility model, the time-of-flight ranging sensor may adjust the lighting according to the calculated signal-to-noise ratio, comprising: and stopping polishing when the signal-to-noise ratio is higher than a preset level, and outputting a histogram.
Fig. 5 illustrates a method of controlling a time-of-flight ranging sensor, according to an embodiment of the present disclosure, the method comprising the steps of: controlling to start polishing, detecting incidence of photons through the SPAD pixel matrix and outputting pulse signals; recording information related to the moment of outputting the pulse signal through the TDC; generating, by a histogram generating means, histogram information based on information related to the time instants at which the pulse signals are output; and monitoring the state of the histogram in real time by a histogram state monitoring device, stopping lighting according to the monitoring result, and outputting the histogram.
The text and drawings are provided as examples only to aid in the understanding of the present disclosure. They should not be construed as limiting the scope of the disclosure in any way. While certain embodiments and examples have been provided, it will be apparent to those of ordinary skill in the art from this disclosure that variations can be made to the embodiments and examples shown without departing from the scope of the disclosure.
According to an embodiment of the present disclosure, there is provided a time-of-flight ranging sensor including a histogram state monitoring device that judges whether or not lighting is required to be stopped by monitoring the state of a histogram in real time, thereby shortening exposure time and reducing overall power consumption; furthermore, the time-of-flight ranging sensor according to embodiments of the present utility model is also capable of characterizing the optical conditions of the current test environment, thereby dynamically controlling the system.
Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. The disclosure is intended to embrace such alterations and modifications that fall within the scope of the appended claims.
Any description of the present utility model should not be construed as implying that any particular element, step, or function is a necessary element to be included in the scope of the claims. The scope of patented subject matter is defined only by the claims.
Claims (7)
1. A time-of-flight ranging sensor comprising histogram state monitoring means, comprising:
a single photon avalanche detector SPAD pixel array configured to detect incidence of photons and output a pulse signal;
a time-to-digital converter TDC configured to record information about the time instant of a pulse signal generated by the SPAD being broken down;
a histogram generation means configured to generate histogram information based on the information recorded by the TDC; and
a histogram state monitoring device configured to monitor the state of the histogram in real time, and stop lighting according to the monitoring result, output the histogram,
the histogram generating means is configured to take the numerical value recorded by the TDC as an address value of the histogram memory, read the data stored in the corresponding address and add 1, and write the numerical value after the addition back to the corresponding address to generate histogram information,
the histogram state monitoring apparatus is configured to include a first register, a second register, and a comparator;
the first register stores a preset first threshold value, and the second register stores a value of a histogram memory of an address corresponding to a numerical value recorded by a current TDC; and is also provided with
The comparator compares the values of the first register and the second register, and stops lighting when the value of the second register is larger than a first threshold value, and outputs a histogram.
2. The time-of-flight ranging sensor of claim 1, wherein the histogram state monitoring apparatus is configured to include a counter configured to count the number of shots and activate the histogram state monitoring apparatus when the count value reaches a second threshold.
3. The time-of-flight ranging sensor according to claim 2, wherein the histogram state monitoring apparatus is configured to include a third register configured to store a value of a histogram memory of an address corresponding to a numerical value of a current TDC record, and a comparator to compare the value of the third register with a third threshold value calculated from a count value of the counter, and to stop lighting and output a histogram when the value of the third register is greater than the third threshold value.
4. The time-of-flight ranging sensor of claim 1, wherein the histogram state monitoring apparatus is configured to include a fourth register that stores a value corresponding to the first address value in the histogram memory,
when the TDC timing start time is earlier than the lighting time, the fourth register stores that the value corresponding to the first address value in the histogram memory corresponds to the intensity of the background light.
5. The time-of-flight ranging sensor of claim 4, wherein the intensity of the lighting is increased when the value stored in the fourth register is greater than a fourth threshold value, and
when the value stored in the fourth register is smaller than the fifth threshold value, the intensity of the lighting is reduced.
6. The time-of-flight ranging sensor of claim 4, wherein the histogram state monitoring apparatus is configured to include a fifth register storing a maximum value among values of the histogram memory corresponding to the address corresponding to the numerical value of the TDC record, and a processor calculating the signal-to-noise ratio from the values in the fourth register and the values stored in the fifth register and the address values corresponding to the values stored in the fifth register.
7. The time-of-flight ranging sensor of claim 6, wherein adjusting the lighting according to the signal-to-noise ratio comprises: and stopping polishing when the signal-to-noise ratio is higher than a preset sixth threshold value, and outputting a histogram.
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