Methods for measuring distance to a target

Abstract

A method for measuring the distance to a target is disclosed, the method comprising: operating a transmitter to generate a first pulse signal and a second pulse signal in a field of view of the transmitter where the target may be present, the first pulse signal having a first pulse frequency f1 and the second pulse signal having a second pulse frequency f2, the first pulse frequency f1 being different from the second pulse frequency f2; operating a detector to detect signals within a predetermined duration after generating the first pulse signal and within a predetermined duration after generating the second pulse signal; storing the detected signals in a memory spanning a period of the first pulse signal and a period of the second pulse signal, respectively; using the detected signals to identify a portion (RP1) of the first pulse signal reflected by the target and a portion (RP2) of the second pulse signal reflected by the target; determining a first virtual distance based on a difference between a reference signal (RS1, RS2) and the detection of the portion (RP1) of the first pulse signal reflected by the target; determining a second virtual distance based on a difference between the reference signal (RS1, RS2) and the detection of the portion (RP2) of the second pulse signal reflected by the target; and determining the distance to the target based on a virtual difference corresponding to the difference between the first virtual distance and the second virtual distance. The first and second virtual distances respectively comprise distances determined within periods of the first and second pulse signals when the reflected portion folds back into the recording periods marked as period 1 and period 2. Thereby, the maximum unambiguous range is extended and memory size requirements are reduced.

Description

Technical Field

[0001] The present disclosure relates to methods and apparatus for measuring distance and / or obtaining distance data. Background Art

[0002] Time-of-Flight (ToF) based systems can be used to provide depth and / or distance information for two-dimensional or three-dimensional imaging or scanning.

[0003] A ToF system can be characterized by its maximum measurable distance, which can also be referred to as its maximum unambiguous range. In an indirect ToF (iToF) system, a continuously modulated signal is transmitted, and the phase difference between the outgoing and returned signals is measured to determine the distance the signal has traveled. Ambiguity can arise from the periodicity of the modulated signal. For example, if the time delay results in a phase change greater than one full cycle, a particular phase measurement can represent multiple possible distances. Each possible distance will be separated by a multiple of half a wavelength of the modulation frequency.

[0004] The maximum unambiguous range is inversely proportional to the modulation frequency. Therefore, by reducing the modulation frequency, the maximum unambiguous range can be extended. However, by reducing the modulation frequency, the range accuracy is also reduced, which is generally undesirable.

[0005] Dorrington et al., in Meas. Sci. Technol. 18, 2007, 2809, describe a solid-state range imaging system capable of simultaneously capturing range and intensity data for every pixel in a scene with submillimeter range accuracy. Dorrington et al. describe a first distance measurement using a modulation signal with a 100 MHz modulation frequency and a second distance measurement using a modulation signal with a 93.75 MHz modulation frequency to determine the actual distance to a target. The use of two modulation frequencies allows for an extension of the maximum unambiguous range. However, this approach only allows for a certain range accuracy per measurement, which decreases with increasing distance. Range accuracy may also be limited by the available optical power of the light source and / or the integration time of the detector used for the distance measurement.

[0006] In direct ToF (dToF) systems using discrete pulses, the maximum range is determined by the memory size (corresponding to the number of histogram bins and their respective bin widths). For example, if a bin width of 200 ps is chosen (for accuracy reasons), this corresponds to 37.5 mm, so a histogram size of 200 bins is required for a range of 7.5 m. Since each bin requires a certain depth, this results in a large amount of memory being required for each pixel. For 3D cameras with a large number of pixels, a trade-off between memory size and the maximum detectable range is inevitable. This is despite the fact that most bins will actually be empty (or only affected by background signals) due to the gaps between pulses and the lack of reflected signals. Some solutions have been proposed to solve this problem, such as spatial or temporal multiplexing, however, none of these approaches are completely satisfactory.

[0007] It is therefore an object of the present disclosure to provide methods, apparatus and systems for measuring distance that solve one or more of the problems set forth above, or at least provide a useful alternative. Summary of the Invention

[0008] In general, the present disclosure addresses one or more of the aforementioned issues by transmitting a first pulse signal comprising a first pulse frequency and a second pulse signal comprising a second pulse frequency toward a target in a transmitter's field of view, wherein the first pulse frequency is different from the second pulse frequency. For each frequency, memory is conserved by using a memory or histogram that spans only one period of that frequency, such that the reflected signal folds back into that period. In this manner, first and second virtual ranges are determined using the reflected portions of the first and second pulse signals, and the range to the target is based on a virtual difference between the first and second virtual ranges.

[0009] According to a first aspect of the present disclosure, a method for measuring a distance to a target includes:

[0010] operating the transmitter to generate a first pulse signal and a second pulse signal in a field of view of the transmitter where a target may be present, the first pulse signal having a first pulse frequency and the second pulse signal having a second pulse frequency, the first pulse frequency being different from the second pulse frequency;

[0011] operating a detector to detect a signal within a predetermined duration after generating the first pulse signal and within a predetermined duration after generating the second pulse signal;

[0012] storing the detected signal in a memory spanning a period of the first pulse signal and a period of the second pulse signal respectively;

[0013] using the detected signals to identify a portion of the first pulse signal reflected by the target and a portion of the second pulse signal reflected by the target;

[0014] determining a first virtual distance based on a difference between a reference signal and detection of the portion of the first pulse signal reflected by the target;

[0015] determining a second virtual distance based on a difference between the reference signal and detection of the portion of the second pulse signal reflected by the target; and

[0016] The distance to the target is determined based on a virtual difference corresponding to a difference between the first virtual distance and the second virtual distance.

[0017] Thus, according to a first aspect, a method for measuring the distance to a target is provided that folds all signals into a single period to save memory, while allowing the true distance to be determined by using two different pulse frequency signals and the difference between two virtual distances. Advantageously, the method can extend the unambiguity range to distances where the target reflectivity is indistinguishable from the background level.

[0018] It is worth noting that each pulse signal does not include a timestamp, so without synchronization, it is impossible to use a single pulse signal to determine which signal pulse has been reflected and received at any point in time. However, because the present method uses two different pulse signals (each with a different frequency and therefore a different period), it is possible to use the virtual difference between them during the measurement period to determine the true distance traveled by each signal.

[0019] The detector may be configured with a time-to-digital converter (TDC) which generates a histogram spanning one cycle for each frequency.Data acquisition using the TDC may be repetitive (ie at the same frequency as the cycle) and / or cumulative.

[0020] The step of determining the distance to the target may include determining a period difference corresponding to a difference between a period of the first pulse signal and a period of the second pulse signal.

[0021] The step of determining the distance to the target may include determining a cycle weight based on the virtual difference and the cycle difference, multiplying the cycle weight by the cycle of the first pulse signal and adding the first virtual distance.

[0022] The step of determining the distance to the target may include determining a period weight based on the virtual difference and the period difference, multiplying the period weight by the period of the second pulse signal and adding the second virtual distance.

[0023] The memory may include a plurality of intervals spanning periods of the first pulse signal and the second pulse signal, respectively, and wherein each interval stores a value representing a signal detected in a predefined measurement window corresponding to a predefined distance or time.

[0024] The predefined measurement window of each interval may correspond to a period difference; a fraction of the period difference or a factor of the period difference.

[0025] The first virtual distance can be determined by calculating the number of intervals that separate the reference interval of the detection signal corresponding to the reference signal (e.g., the peak) and the signal interval of the detection signal corresponding to the part (e.g., the peak) of the first pulse signal reflected by the target; and the second virtual distance can be determined by calculating the number of intervals that separate the reference interval of the detection signal corresponding to the reference signal (e.g., the peak) and the signal interval of the detection signal corresponding to the part (e.g., the peak) of the second pulse signal reflected by the target.

[0026] The distance can be determined with a resolution much better than the interval width alone, i.e., the difference between the reference peak and the reflected signal peak can be determined as a fraction of the interval width (e.g., if interval width = 250ps corresponds to ~37.5mm, and the target is at 500mm, then the difference between the reflected signal peak and the reference peak is 500mm / 37.5mm / interval = 13.33 intervals).

[0027] The method may further comprise:

[0028] operating the transmitter to generate a third pulse signal in a field of view of the transmitter where a target may be present, the third pulse signal having a third pulse frequency that is different from the first pulse frequency and the second pulse frequency;

[0029] operating a detector to detect a signal within a predetermined duration after generating the third pulse signal;

[0030] storing the detected signal in a memory spanning a period of a third pulse signal;

[0031] using the detected signal to identify a portion of a third pulse signal reflected by the target;

[0032] determining at least two of a first virtual distance, a second virtual distance, and a third virtual distance, the third virtual distance being based on a difference between a reference signal and detection of the portion of the third pulse signal reflected by the target; and

[0033] The distance to the target is determined based on a virtual difference corresponding to a difference between at least two of the first virtual distance, the second virtual distance, and the third virtual distance.

[0034] Using a third pulse signal may help overcome problems when one of the reflected signals folds over the reference signal and becomes indistinguishable from the reference signal.

[0035] The method may include operating a transmitter to successively generate a first pulse signal, a second pulse signal, and a third pulse signal.

[0036] The step of determining at least two of the first virtual distance, the second virtual distance, and the third virtual distance may include selecting at least two of the first virtual distance, the second virtual distance, and the third virtual distance based on one or more of:

[0037] the value and / or profile of the detection signal corresponding to the reference signal;

[0038] a value and / or profile of the detection signal corresponding to the portion of the first pulse signal reflected by the target;

[0039] a value and / or profile of the detection signal corresponding to the portion of the second pulse signal reflected by the target; and

[0040] The value and / or profile of the detection signal corresponds to the portion of the third pulse signal reflected by the target.

[0041] The third virtual distance may be determined by counting the number of memory bins that separate a reference bin including the detection signal corresponding to the reference signal and a signal bin including the detection signal corresponding to the portion of the third pulse signal reflected by the target.

[0042] The step of determining the distance to the target may include determining a period difference between at least two of a period of the first pulse signal, a period of the second pulse signal, and a period of the third pulse signal.

[0043] The step of determining the distance to the target may include determining a cycle weight based on the virtual difference and the cycle difference, and at least one of:

[0044] Multiplying the period weight by the period of the first pulse signal and adding the first virtual distance;

[0045] Multiplying the period weight by the period of the second pulse signal and adding the second virtual distance; and

[0046] The period weight is multiplied by the period of the third pulse signal and added to the third virtual distance.

[0047] The reference signal may be one of: a start signal; a synchronization signal; a signal stored in the first memory interval; a cover glass reflectivity; or a crosstalk signal.

[0048] In some embodiments, a low pulse frequency can be used to determine a reference signal. The reference signal can then be subtracted from all subsequent measurements.

[0049] According to a second aspect of the present disclosure, a computer program comprises computer-readable instructions configured to cause a processor to perform the method according to the first aspect.

[0050] According to a third aspect of the present disclosure, a non-transitory computer-readable medium includes the computer program according to the second aspect.

[0051] According to a fourth aspect of the present disclosure, a device for measuring a distance to a target includes:

[0052] a transmitter having a field of view in which a target may be present, the transmitter being configured to generate a first pulse signal and a second pulse signal in the field of view, the first pulse signal having a first pulse frequency and the second pulse signal having a second pulse frequency, the first pulse frequency being different from the second pulse frequency;

[0053] a detector configured to detect a signal within a predetermined duration after the first pulse signal is generated and within a predetermined duration after the second pulse signal is generated; and

[0054] a memory configured to store the detected signal, wherein the memory spans a period of the first pulse signal and a period of the second pulse signal, respectively; and

[0055] The controller is configured as:

[0056] using the detected signals to identify a portion of the first pulse signal reflected by the target and a portion of the second pulse signal reflected by the target;

[0057] determining a first virtual distance based on a difference between a reference signal and detection of the portion of the first pulse signal reflected by the target;

[0058] determining a second virtual distance based on a difference between the reference signal and detection of the portion of the second pulse signal reflected by the target; and

[0059] The distance to the target is determined based on a virtual difference corresponding to a difference between the first virtual distance and the second virtual distance.

[0060] The detector may comprise a pixel array, at least one or each pixel of the pixel array being configured to detect a signal corresponding to the portion of the first pulse signal reflected by the target and / or the portion of the second pulse signal reflected by the target.

[0061] The memory may include a plurality of bins, and each bin may be shared by a plurality of pixels of the pixel array.

[0062] The memory may span only the period of the first pulse signal and / or only the period of the second pulse signal, respectively.

[0063] It will be appreciated that any feature described in relation to the first, second or third aspects may also be applicable to the apparatus according to the fourth aspect, and vice versa.

[0064] Compared with known distance measurement methods, the method and apparatus disclosed herein may have the following advantages:

[0065] 1. Extended the maximum unambiguous range.

[0066] 2. The accuracy of the distance measurement can be constant and / or independent of the distance to the target and / or the extension of the maximum unambiguity range.

[0067] 3. Reduced memory size requirements, which may allow for a reduced footprint of the disclosed systems and / or devices and / or reduce the cost of producing the disclosed systems and / or devices.

[0068] 4. Reduced memory size requirements may allow for increased memory space per pixel and / or an increase in the number of pixels operating simultaneously, thereby improving the performance of the disclosed systems and devices.

[0069] 5. Eliminate mixing or interference between the reference signal and a portion of the first, second and / or third pulse signals reflected by the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Some preferred embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0071] Figure 1 A flow chart outlining the steps of a method for measuring the distance to a target according to an embodiment of the present disclosure is shown;

[0072] Figure 2A A plurality of first histograms are shown, each corresponding to a Figure 1 A portion of the method generates a period of a first pulse signal;

[0073] Figure 2B A plurality of second histograms are shown, each corresponding to a Figure 1 a period of the second pulse signal generated as part of the method;

[0074] Figure 3 shows that the overview can be combined with Figure 1 Flowchart of further steps in the method;

[0075] Figure 4A A plurality of first histograms are shown, each corresponding to a Figure 3 A portion of the method generates a period of a first pulse signal;

[0076] Figure 4BA plurality of second histograms are shown, each corresponding to a Figure 3 a period of the second pulse signal generated as part of the method;

[0077] Figure 4C A plurality of third histograms are shown, each corresponding to a Figure 3 a period of a third pulse signal generated as part of the method;

[0078] Figure 5 A system for measuring the distance to a target according to the present disclosure is shown;

[0079] Figure 6 Another embodiment of a system for measuring distance to a target according to the present disclosure is shown;

[0080] Figure 7 An apparatus for obtaining data required to measure the distance to a target according to the present disclosure is shown;

[0081] Figure 8 An exemplary embodiment is shown, wherein Figure 7 The device is integrated into the mobile user equipment; and

[0082] Figure 9A and 9B Another exemplary embodiment is shown, wherein Figure 7 The device is part of a motor vehicle. DETAILED DESCRIPTION

[0083] Generally speaking, the present disclosure provides methods, apparatus, and systems for measuring the distance to a target having a large unambiguous range, small memory size requirements, and / or the ability to measure the distance to a target with an accuracy that remains constant and / or independent of the distance to the target.

[0084] Some examples of the method and associated systems and devices are given in the accompanying drawings.

[0085] Figure 1 An exemplary flow chart of a method 100 for measuring the distance to a target according to the present disclosure is shown. Method 100 can be considered a direct time-of-flight method. In step 102, method 100 includes operating a transmitter to generate a first pulse signal and a second pulse signal in the transmitter's field of view where the target may be present. The first pulse signal has a first pulse frequency, and the second pulse signal has a second pulse frequency, where the first pulse frequency is different from the second pulse frequency.

[0086] In step 104 , the method 100 includes operating a detector to detect a signal within a predetermined duration after generating the first pulse signal and within a predetermined duration after generating the second pulse signal.

[0087] In step 106 , the method 100 includes storing the detected signal in a memory spanning a period of the first pulse signal and a period of the second pulse signal, respectively.

[0088] In step 108 , method 100 includes using the detected signal to identify a portion (eg, a peak) of the first pulse signal reflected by the target and a portion (eg, a peak) of the second pulse signal reflected by the target.

[0089] In step 110 , method 100 includes determining a first virtual distance based on a difference between a reference signal and detection of the portion of the first pulse signal reflected by the target.

[0090] In step 112 , method 100 includes determining a second virtual distance based on a difference between the reference signal and the detection of the portion of the second pulse signal reflected by the target.

[0091] In step 114 , method 100 includes determining a distance to the target based on a virtual difference corresponding to a difference between the first virtual distance and the second virtual distance.

[0092] In this embodiment, the step of determining the distance to the target includes determining a period difference corresponding to the difference between the period of the first pulse signal and the period of the second pulse signal; determining a period weight based on the virtual difference and the period difference; and multiplying the period weight by the period of the first pulse signal and adding the first virtual distance. In other embodiments, the period weight may be multiplied by the period of the second pulse signal and added to the second virtual distance to determine the distance to the target.

[0093] In this embodiment, the detector includes a time-to-digital converter (TDC) that generates a histogram spanning one cycle for each frequency and stores the detected values ​​in a memory. Thus, data acquisition using the TDC is repeated at the same frequency as the cycle, so that data for one cycle is kept in the memory at any point in time. However, for the purpose of illustration, Figure 2A and 2B A plurality of consecutive histograms are shown which are recorded for each of the first and second pulse signals, respectively. Thus, the reflected parts of the first pulse signal and the second pulse signal are recorded in the histograms. Figure 2A Multiple first histograms are shown. Figure 2A Each of the first histograms shown corresponds to a period of the first pulse signal. Figure 2B A plurality of second histograms are displayed. Figure 2B Each second histogram shown in corresponds to a period of the second pulse signal. Each first histogram and each second histogram includes a plurality of intervals.

[0094] The first pulse frequency f1 and / or the second pulse frequency f2 can be selected based on the desired size of the memory. The memory may need to store one of the first and second histograms, spanning only one period of the first and second pulse signals, respectively. Therefore, by increasing the first pulse frequency f1 and / or the second pulse frequency f2, the period of the first and / or second pulse signals, respectively, can be reduced, which can result in a reduction in the size of the first and second histograms. Consequently, the size of the memory can be further reduced.

[0095] The first pulse frequency f1 and / or the second pulse frequency f2 may be greater than 100 to 200 MHz. The first pulse frequency f1 and / or the second pulse frequency f2 may be in the range of approximately 100 to 350 MHz. In this embodiment, the first pulse frequency f1 is 250 MHz and the second pulse frequency f2 is 266.6 MHz. It should be understood that in other embodiments, the first pulse frequency may be greater than or less than 250 MHz, and / or the second pulse frequency may be greater than or less than 266.6 MHz. For example, in other embodiments, the first frequency may be approximately 125 MHz and / or the second frequency may be approximately 133.3 MHz.

[0096] Using a first pulse frequency f1 of 250 MHz and a second pulse frequency f2 of 266.6 MHz, the maximum unambiguous range can be calculated to be approximately 9 meters. In comparison, the maximum unambiguous range for distance measurement using a single pulse frequency of 250 MHz or 266.6 MHz corresponds to approximately 0.6 meters or 0.5625 meters, respectively. Therefore, by using a first pulse signal having a first pulse frequency and a second pulse signal having a second pulse frequency, the maximum unambiguous range can be extended. At the same time, the first and second frequencies can be selected to be higher than the frequency of a single pulse signal that can be used for distance measurement, which can reduce the required memory size, as described below.

[0097] In this embodiment, the pulse width of the first pulse signal is the same as the pulse width of the second pulse signal. For example, the pulse width of the first pulse signal and the second pulse signal can be in the range of 100 ps to 500 ps. It should be understood that in other embodiments, the pulse width of the first pulse signal can be different from the pulse width of the second pulse signal.

[0098] The width of each bin of each first histogram and each second histogram may be selected based on the accuracy required by the method 100. In this embodiment, the width of each bin is 250 ps, ​​corresponding to c*250 ps / 2=37.5 mm, where c is the speed of light. Figure 2A and 2BAs shown, this results in 16 bins per period of the first pulse signal and 15 bins per period of the second pulse signal. The first pulse frequency f1 and the second pulse frequency f2 can be selected such that there is at least one bin difference between the period of the first pulse signal and the period of the second pulse signal. In other words, the difference between the periods of the first and second pulse signals can be equal to one bin; a fraction of one bin; or multiple bins. It should be understood that, additionally or alternatively, the width of each bin of each first histogram and / or each second histogram can be selected based on the size of a memory that can be used to store one of the first and second histograms.

[0099] As described above, the method 100 of determining a distance to a target includes determining a first virtual distance to the target and a second virtual distance to the target.

[0100] The term "first virtual distance" may be considered to encompass a first distance that may or may not be the actual or correct distance to the target. This is because it is not certain to which transmit pulse the detected reflected portion of the first signal belongs or is associated. Therefore, the first virtual distance includes the distance when the reflected portion is reflected back into the recording period (at Figure 2A The distance is determined during the period of the first pulse signal when the period is marked as period 1. The reflected portion of the first pulse signal is recorded as peak RP1 in the first histogram.

[0101] The term "second virtual distance" may be considered to encompass a second distance that may or may not be the actual or correct distance to the target. This is because it is not certain to which transmit pulse the reflected portion of the detected second signal belongs or is associated. Therefore, the second virtual distance includes the reflected portion when it is reflected back into the recording period (at Figure 2B The distance is determined during the period of the second pulse signal when the period is marked as period 1). The reflected portion of the second pulse signal is recorded as peak RP2 in the second histogram.

[0102] The first virtual distance is determined by comparing the reflected portion RP1 of the first pulse signal with the first reference signal RS1. The second virtual distance is determined by comparing the reflected portion RP2 of the second pulse signal with the second reference signal RS2. The first and second reference signals RP1 and RP2 can be considered to represent zero-distance signals.

[0103] The first reference signal RS1 includes another part of the first pulse signal reflected by a part of the system or device including the transmitter. The second reference signal RS2 includes another part of the second pulse signal reflected by the same part of the system or device including the transmitter. For example, as described below, the transmitter can be part of a camera system such as a direct time-of-flight (dToF) camera system, or part of a sensor device such as a direct time-of-flight (dToF) sensor device. The system or device may include a cover portion, for example as a cover glass. As described below, the cover portion can be arranged at a certain distance from the transmitter. The distance between the cover portion and the transmitter is known.

[0104] The method 100 may include detecting a first reference signal RS1 and a second reference signal RS2. Since the distance between the cover portion and the transmitter is known, the first and second reference signals RS1 and RS2 are set to zero distance signals. The first virtual distance VD1 is determined by the difference between the peak value of the first reference signal RS1 and the peak value of the reflected portion RP1 of the first pulse signal. Figure 2A In the example shown, the first virtual distance VD1 is 5 intervals, which corresponds to 0.1875 m, for example, five times the interval width of 37.5 mm. Similarly, the second virtual distance VD2 is determined by the difference between the peak value of the second reference signal RS2 and the peak value of the reflected part RP2 of the second pulse signal. Figure 2B In the example shown, the second virtual distance VD2 is 7 intervals, which corresponds to 0.2625 m, for example, seven times the interval width of 37.5 mm. By using the first and second reference signals RS1, RS2, respectively, to determine the first and second virtual distances VD1, VD2, no synchronization is required between the emission of the first and second pulse signals and the detection of the reflected portions of the first and second pulse signals, respectively.

[0105] The step of determining the distance to the target (step 114) includes determining a virtual difference DV between the first virtual distance VD1 and the second virtual distance VD2, determining a period difference DP corresponding to the difference between the period of the first pulse signal and the period of the second pulse signal, determining a period weight PW based on the virtual difference DV and the period difference DP, multiplying the period weight PW by the period of the first pulse signal (or the second pulse signal), and adding the first virtual distance (or the second virtual distance).

[0106] For example, as described above, the first pulse frequency f1 and the second pulse frequency f2 are different. Therefore, the period of the first pulse signal and the period of the second pulse signal are also different. In this embodiment, the period of the first pulse signal is 4 ns, corresponding to 0.6 m or 16 intervals. The period of the second pulse signal is 3.75 ns, equivalent to 0.5625 m or 15 intervals.

[0107] like Figure 2A and 2B As shown, the difference between the peak values ​​RP1 and RP2 in period 1 is two intervals, which corresponds to the virtual difference between the first and second virtual distances VD1 and VD2. It should be understood that in other embodiments, the virtual difference DV between the first and second virtual distances may be more or less than two intervals.

[0108] In this embodiment, there is an interval difference between the period of the first pulse signal and the period of the second pulse signal. In other words, the period difference DP is equivalent to one interval, and the virtual difference DV is equivalent to two intervals. The period weight PW is the virtual difference DV divided by the period difference DP. In this case, the period weight PW is 2. Multiplying the period weight PW by the period of the first or second pulse signal determines the actual distance, which is added to the first virtual distance VD1 or the second virtual distance to determine the real distance to the target. In this embodiment, the actual distance is Figure 2A and 2B In the period 3 of , it is equivalent to the period 1 plus two periods determined by the virtual difference DV of the two intervals. Therefore, the distance R to the target is determined based on the actual distance to be added to the first virtual distance VD1 or the second virtual distance VD2, so that the distance R is calculated by equation (1) as follows:

[0109] R=PW*T1+VD1=PW*T2+VD2 (1)

[0110] Where T1 is the period of the first pulse signal, and T2 is the period of the second pulse signal. Figure 2A and 2B In the example shown, the distance R to the target can be calculated as 2*0.6 m+5*37.5 mm=2*0.5625+7*37.5 mm=1.3875 m.

[0111] Determination of the first virtual distance VD1 and the second virtual distance VD2 may require a certain level of accuracy in order to determine the true distance R. The required accuracy may depend on the amount of error, such as false positive errors, that can be tolerated in determining the first virtual distance VD1 and the second virtual distance VD2. For example, when a 1% error is tolerated, the required accuracy may be determined as 0.5*1 intervals. In other words, the accuracy in determining the first virtual distance VD1 and the second virtual distance VD2 needs to be less than the difference between the maximum unambiguous range of distance measurement using a single pulse frequency of 250 MHz and the maximum unambiguous range of distance measurement using a single pulse frequency of 266.6 MHz, divided by 2. For example, the required accuracy corresponds to (0.6 m - 0.5625 m) / 2 = ~19 mm, corresponding to 0.5*1 intervals.

[0112] Furthermore, the accuracy of the distance measurement can depend on the bin width of the first or second histogram, the pulse width of the first or second pulse signal, the optical power of the first or second pulse signal, or the timing jitter of the detector used to detect the reflected portion of the first and second pulse signals. Therefore, the accuracy of the distance measurement can be considered independent of the first and second pulse frequencies. In other words, the accuracy of the distance measurement can be considered constant and / or independent of the distance to the target. This means that the distance to the target can be measured until the reflected portion of the first and / or second signals becomes indistinguishable from ambient light.

[0113] Figure 3 shows that an overview can be formed Figure 1 Flowchart of further steps of a portion of method 100 .

[0114] At step 150, method 100 includes operating the transmitter to generate a third pulse signal in the transmitter's field of view where a target may be present. The third pulse signal has a third pulse frequency f3. The third pulse frequency f3 is different from the first pulse frequency f1 and the second pulse frequency f2. For example, the third pulse frequency f3 may be greater than or less than the first pulse frequency f1 and / or the second pulse frequency f2. The transmitter may be operated to continuously generate the first pulse signal, the second pulse signal, and the third pulse signal.

[0115] In step 152 , the method 100 includes operating a detector to detect a signal within a predetermined duration after generating the third pulse signal.

[0116] In step 154 ​​, method 100 includes storing the detected signal in a memory spanning a period of the third pulse signal.

[0117] At step 156 , method 100 includes using the detected signal to identify a portion of the third pulse signal that was reflected by the target.

[0118] In step 158 , method 100 includes determining at least two of a first virtual distance, a second virtual distance, and a third virtual distance, the third virtual distance being based on a difference between the reference signal and detection of the portion of the third pulse signal reflected by the target.

[0119] In step 160 , method 100 includes determining a distance to the target based on a virtual difference corresponding to a difference between at least two of the first virtual distance, the second virtual distance, and the third virtual distance.

[0120] The following will refer to Figures 4A to 4C Describe in more detail Figure 3 The method steps shown.

[0121] Figure 4AA series of first histograms are shown, wherein each first histogram corresponds to a period of the first pulse signal. Figure 4B A series of second histograms are shown, wherein each second histogram corresponds to a period of the second pulse signal. Figure 4C A series of third histograms are shown, wherein each third histogram corresponds to a period of the third pulse signal.

[0122] As described above, the first pulse frequency, the second pulse frequency, and the third pulse frequency may be selected based on a desired or required unambiguity range of the method 100 and / or a size of a memory.

[0123] The third pulse frequency f3 can be higher than 100 to 200 MHz. The third frequency f3 can be in the range of approximately 100 to 350 MHz. In this embodiment, the third pulse frequency f3 is higher than the first and second pulse frequencies f1 and f2. The first pulse frequency f1, the second pulse frequency f2, and the third pulse frequency f3 are selected so that there is an interval difference between each of the periods of the first pulse signal, the second pulse signal, and the third pulse signal. In this embodiment, the third pulse frequency is 307 MHz. It should be understood that in other embodiments, the third pulse frequency can be greater than or less than 307 MHz. As described above, the first pulse frequency f1 is 250 MHz and the second pulse frequency is 266.6 MHz.

[0124] The pulse width of the third pulse signal is the same as the pulse width of the first and second pulse signals. For example, the pulse widths of the first, second, and third pulse signals are in the range of 100 ps to 500 ps. It should be understood that in other embodiments, the pulse widths of the first pulse signal, the second pulse signal, and / or the third pulse signal may be different.

[0125] In this embodiment, as described above, the bin width of each bin in each of the first, second, and third histograms is 250 ps, ​​which corresponds to 37.5 mm. This results in 16 bins per cycle of the first pulse signal, 15 bins per cycle of the second pulse signal, and 14 bins per cycle of the third pulse signal. Figures 4A to 4C shown.

[0126] The step of determining the distance to the target (step 160 ) includes determining at least two of a first virtual distance, a second virtual distance, and a third virtual distance.

[0127] The term "third virtual distance" may be considered to encompass a third distance that may or may not be the actual or correct distance to the target. This is because it is not certain to which transmit pulse the detected portion of the third signal reflected by the target belongs or is associated. Therefore, the third virtual distance includes the portion of the third signal reflected by the target when it is reflected back into the recording period (at Figure 4C The distance determined during the period of the third pulse signal is marked as period 1 in FIG. The reflected portion of the third pulse signal is recorded as peak RP3 in the third histogram.

[0128] The step of determining at least two of the first virtual distance, the second virtual distance, and the third virtual distance includes selecting at least two of the first virtual distance, the second virtual distance, and the third virtual distance to be determined. In other words, selecting two of the first virtual distance, the second virtual distance, and the third virtual distance is based on the value (e.g., intensity) and / or profile (e.g., shape) of the first reference signal RS1 and / or the reflected portion RP1 of the first pulse signal, the value and / or profile of the second reference signal RS2 and / or the reflected portion RP2 of the second pulse signal, and / or the value and / or profile of the third reference signal RS3 and / or the reflected portion of the third pulse signal.

[0129] The third reference signal RS3 includes another portion of the third pulse signal that is partially reflected by a cover of a system or device including the transmitter. The method 100 in this example includes detecting the third reference signal RS3 and the reflected portion of the third pulse signal.

[0130] For example, in Figure 4A In the example, when RP1 folds back into the cycle recorded in the memory, the peak of the reflected portion RP1 of the first pulse signal overlaps or coincides with the peak of the first reference signal RS1. Therefore, it may be difficult or impossible to determine the first virtual distance. The overlap causes the intensity of the peak of the reflected portion RP1 of the first pulse signal and the intensity of the peak of the reference signal RS1 to change, for example, increase, compared to the intensity of the peak of the second and third reference signals RS2 and RS3 and / or the intensity of the peak of the reflected portion RP2 and RP3 of the second and third pulse signals. The overlap also causes the shape of the peak of the reflected portion RP1 of the first pulse signal and the shape of the peak of the reference signal RS1 to change, compared to the shape of the peak of the second and third reference signals RS2 and RS3 and / or the shape of the peak of the reflected portion RP2 and RP3 of the second and third pulse signals.

[0131] The intensities and / or shapes of the peaks of the second and third reference signals RS2, RS3 are similar because they are not affected by the presence of the reflected portion of the second or third pulse signal, respectively. Similarly, the intensities and / or shapes of the peaks of the reflected portions RP2, RP3 of the second and third pulse signals are similar because they are not affected by the presence of the second and third reference signals, respectively. Figure 4B and 4C shown.

[0132] Due to the difference between the period of the first pulse signal, the period of the second pulse signal, and the period of the third pulse signal, for example, a one-interval difference, the peak values ​​of the reflected portions RP2 and RP3 of the second and third pulse signals are shifted relative to the peak values ​​of the corresponding second and third reference signals RS2 and RS3 by at least one interval. In this embodiment, the peak value of the reflected portion RP2 of the second pulse signal is shifted relative to the peak value of the second reference signal RS2 by two intervals, and the peak value of the reflected portion RP3 of the third pulse signal is shifted relative to the peak value of the third reference signal RS3 by four intervals, as shown in FIG. Figure 4B and 4C Therefore, it is possible to calculate the second virtual distance and the third virtual distance, but it is impossible to calculate the first virtual distance, so in this embodiment, the second virtual distance and the third virtual distance are selected.

[0133] The second virtual distance VD2 is determined by comparing the reflected portion RP2 of the second pulse signal with the second reference signal RS2. The third virtual distance is determined by comparing the reflected portion RP3 of the third pulse signal with the third reference signal RS3. For example, the second virtual distance VD2 can be determined based on the difference between the peak value of the second reference signal RS2 and the peak value of the reflected portion RP2 of the second pulse signal. Figure 4B In the example shown, the second virtual distance VD2 is 2 intervals, which corresponds to twice the interval width of 0.075 m, for example 37.5 mm.

[0134] The third virtual distance VD3 can be determined based on the difference between the peak value of the third reference signal RS3 and the peak value of the reflected portion RP3 of the third pulse signal. Figure 4C In the example shown, the third virtual distance VD3 is 4 intervals, which corresponds to four times the interval width of 0.15 m, for example 37.5 mm.

[0135] The step of determining the distance to the target (step 160 ) includes determining a virtual difference corresponding to a difference between at least two of the first virtual distance, the second virtual distance, and the third virtual distance.

[0136] The step of determining the distance (step 160) includes determining the period difference between the period of the second pulse signal and the period of the third pulse signal. As described above, there is an interval difference between each of the periods of the first pulse signal, the second pulse signal, and the third pulse signal. In this embodiment, the period of the second pulse signal is 3.75 ns, corresponding to 0.5625 m or 15 intervals. The period of the third pulse signal is 3.26 ns, corresponding to 0.525 m or 14 intervals.

[0137] The distance to the target is determined based on the difference DV between the selected second virtual distance VD2 and the third virtual distance VD3. Figure 4B and 4C As shown, the difference between the peak values ​​RP2 and RP3 in period 1 is two intervals, which corresponds to the difference between the second and third virtual distances VD2, VD3. It should be understood that in other embodiments, the difference between the first and second virtual distances may be more or less than two intervals.

[0138] As previously mentioned, the period difference DP is equivalent to one interval, and the virtual difference DV is equivalent to two intervals. The period weight PW is the virtual difference DV divided by the period difference DP. In this case, the period weight PW is 2. Multiplying the period weight PW by the period of the first or second pulse signal determines the actual distance to be added to the first virtual distance VD1 or the second virtual distance to determine the actual distance to the target. In this embodiment, the actual distance is Figure 4B and 4C In the period 3 of , it is equivalent to the period 1 plus two periods determined by the virtual difference DV of the two intervals. Using the above equation 1, the distance R to the target can be calculated as 2*0.5625m+2*37.5mm=2*0.525m+4*37.5mm=1.2m.

[0139] Therefore, about Figure 3 、 Figure 4A 、 Figure 4B and Figure 4C The described method steps allow eliminating mixing or interference between at least one of the first, second and third reference signals RS1 , RS2 , RS3 and at least one of the respective reflected parts of the first, second and third pulse signals RP1 , RP2 , RP3 .

[0140] It should be understood that in some embodiments, the transmitter can be operated to generate the first pulse signal, the second pulse signal, and the third pulse signal only when the target is in the transmitter's field of view. For example, in use, the target may be located at a certain distance from the transmitter before the first pulse signal, the second pulse signal, and the third pulse signal are generated. However, in other embodiments, the transmitter may be operated to generate the first pulse signal, the second pulse signal, and the third pulse signal before the target is in the transmitter's field of view.

[0141] It will also be understood that peaks (e.g., intervals) in the histograms associated with the first, second and third reference signals RS1, RS2, RS3 and / or peaks (e.g., intervals) associated with the reflected portions RP1, RP2, RP3 of the first, second and third pulse signals can be interpolated for determining the above-mentioned distances, such as virtual distances, rather than using intervals with maximum values / intensities.

[0142] Figure 5 2 shows a system 220 for measuring a distance R to a target 222 according to the present disclosure. The system 220 is provided in the form of a direct time-of-flight (dToF) camera system. The system 220 includes a camera having a field of view 226 (composed of Figure 5 The transmitter 224 is configured to generate a first pulse signal and a second pulse signal toward a target 222 in a field of view 226. The first pulse signal and the second pulse signal are represented by Figure 5 The first pulse signal includes a first pulse frequency f1 and the second pulse signal includes a second pulse frequency f2. As described above, the first pulse frequency f1 is different from the second pulse frequency f2.

[0143] The transmitter 224 can also be configured to generate a third pulse signal toward the target 222 in the field of view 226. The third pulse signal, also indicated by reference numeral 228, includes a third pulse frequency f3. As described above, the third pulse frequency f3 is different from the first and second pulse frequencies f1, f2.

[0144] The emitter 224 can be provided in the form of a pulsed light emitter or a pulsed light emitter array, such as a pulsed laser diode, a vertical cavity surface emitting laser (VCSEL), a vertical cavity surface emitting laser (VCSEL) array, etc. The first pulse signal, the second pulse signal, and the third pulse signal 228 can include infrared radiation or light. For example, the emitter 224 can be configured to emit light or radiation having a wavelength in the range of about 900 nm to about 1.5 μm.

[0145] System 220 includes a detector 230 configured to detect a portion of a first pulse signal reflected by target 222 and a portion of a second pulse signal reflected by target 222. Detector 230 may additionally be configured to detect a portion of a third pulse signal reflected by target 222. The reflected portions of the first, second, and third signals are Figure 5 denoted by reference numeral 232. The detector 30 may be provided in the form of a single photon avalanche diode (SPAD), a silicon photomultiplier tube or other high-speed detector.

[0146] System 220 includes a controller 234 configured to determine a distance R to target 222 based on the first virtual distance and the second virtual distance as described above.

[0147] Controller 234 may additionally be configured to determine a third virtual distance.As described above, in such embodiments, controller 234 may be configured to determine the distance to target 222 based on at least two of the first virtual distance, the second virtual distance, and the third virtual distance.

[0148] The controller 234 can be configured to control the emitter 224 and the detector 230. In other words, the controller 234 can be arranged to communicate with the emitter 224 to control the emission of the first pulse signal, the second pulse signal, and the third pulse signal 228. In use, for example, when the emitter 224 is provided in the form of an array of pulsed light emitters, the controller 234 can operate the emitter 224 to scan the target. The controller 234 can be arranged to communicate with the detector 230 to control the detection of the reflected portions of the first, second, and third pulse signals 232. In some embodiments, the controller 234 can be configured to synchronize the emission of the first, second, and third pulse signals 228 and the detection of the reflected portions 232 of the first, second, and third pulse signals.

[0149] like Figure 5 As shown, the system 220 includes a cover portion 236, which can be provided in the form of a cover glass. The cover portion 236 is arranged in front of the emitter 224 and the detector 230. The cover portion 236 is arranged at a distance EC from the emitter 224. The cover portion 236 is arranged so that the reflected portions of the first, second and third pulse signals pass through the cover portion 236 toward the detector 230. Figure 5 Another portion of the first, second, and / or third pulse signals, denoted by reference numeral 238 in FIG, is reflected by the cover portion 236 and detected by the detector 230. As described above, the other reflected portions of the first, second, and third pulse signals are detected as the first reference signal RS1, the second reference signal RS2, and the third reference signal RS3, respectively.

[0150] The system 220 includes an optical element 240. The optical element 240 is provided in the form of a lens or the like. The optical element 240 is arranged to direct and / or focus the reflected portions 232 of the first, second, and third pulse signals and the first, second, and third reference signals 238 onto the detector 230.

[0151] System 220 can be used, for example, for two-dimensional or three-dimensional imaging or scanning of a target 222. Detector 230 includes a pixel array 242. Pixel array 242 can be provided in the form of a two-dimensional pixel matrix. In use, distance R can be measured, for example, simultaneously, for a plurality of pixels 244 or for each individual pixel 244. Each pixel 244 in pixel array 242 is configured to detect the reflected portion of the first, second, and third pulse signals. Thus, as described above, distance R can be determined for a plurality of pixels 244 or for each pixel 244. This can result in distance information corresponding to a point on target 222. This distance information can be used to convert a two-dimensional image of target 222 into a three-dimensional image of target 222. System 220 includes another controller 246 in the form of an image processor. Another controller 246 is configured to use the distance information to convert the two-dimensional image of target 222 into a three-dimensional image. System 220 includes an output device 248, such as a display or screen, for displaying the three-dimensional image of target 222.

[0152] In this embodiment, multiple pixels 244 of pixel array 242 share a memory for storing the first, second, and third histograms. For example, a 2x2 pixel array can share the same memory. The memory can be considered integral to or part of pixel array 242. The memory can be large enough to store a histogram spanning only the period of the first, second, and third pulse signals. The first, second, and third pulse frequencies can be selected so that the required memory size is reduced and / or compatible with the required size of each pixel. As described above, by generating the first, second, and third pulse signals, the maximum unambiguous range is increased compared to distance measurement using a single pulse signal. This allows the use of higher first, second, and third pulse frequencies compared to distance measurement using a single pulse signal. Consequently, the period of the first, second, and third pulse signals is reduced, which in turn allows the required memory size to be reduced. This makes the memory compatible with the required size of each pixel, allowing the system 220 to have a reduced footprint and / or lower production costs.

[0153] Figure 6 Another embodiment of a system for measuring the distance to a target according to the present disclosure is shown. Figure 6 The system shown is similar to Figure 5 Therefore, like features are indicated by like reference numerals increased by 100.

[0154] As above about Figure 5 As depicted, system 320 may be used for imaging or scanning, such as three-dimensional imaging or scanning, of target 322. Figure 6As shown, target 322 comprises a three-dimensional structure or object, such as a building. It should be understood that in other embodiments, the target may comprise other two-dimensional or three-dimensional structures or objects. System 320 includes an emitter 324, a controller 334, a detector 330, and an image processor 346. A three-dimensional image of target 322 may be displayed by an output device 348.

[0155] Figure 7 An apparatus 400 for obtaining data required to measure a distance R to a target 422 according to the present disclosure is shown. The apparatus 400 is provided in the form of a direct time-of-flight sensor (dToF). The apparatus 400 includes the apparatus 400 described above with reference to Figure 5 Many features of the described system 220 are similar. Therefore, like features are indicated by like reference numerals increased by 200.

[0156] However, it should be understood that Figure 5 The controller, further controller, and output device shown are not part of the apparatus 400 and may be provided separately from the apparatus 400. For example, the controller, further controller, and output device may be part of another device or system and / or may be provided remotely.

[0157] The apparatus 400 includes a transmitter 424. The transmitter 424 may include the Figure 5 Any features of transmitter 424 described.

[0158] The apparatus 400 includes a detector 430. The detector 430 may include the Figure 5 For example, detector 430 is configured to detect a portion 432 of first pulse signal 428 reflected by target 422, a portion 432 of second pulse signal 428 reflected by target 422, and a portion 432 of third pulse signal 428 reflected by target 422, so as to allow determination of the distance to target 422 based on at least two of the first virtual distance, the second virtual distance, and the third virtual distance.

[0159] The systems 220 , 320 and / or the apparatus 400 may be part of or integrated into another apparatus, device and / or system.

[0160] Figure 8 An exemplary embodiment is shown in which the apparatus 400 is part of or integrated into another device. The device is constituted by a mobile user device or a handheld computing device, etc. In this embodiment, the mobile user device is provided in the form of a smart phone 405.

[0161] In this embodiment, the controller, the further controller, and the output device may be provided by one or more controllers (e.g., processors) and output devices of the smartphone 405. As described above, the apparatus 400 may be used for imaging or scanning, such as two-dimensional or three-dimensional imaging or scanning, of a target 422. In use, for example, the smartphone 405 may be located at a distance R from the target 422 such that the target 422 is within the field of view 426 of the transmitter 424 before operating the transmitter 424 to generate the first, second, and third pulse signals 428, as described above.

[0162] Figure 9A and 9B Another exemplary embodiment is shown in which the apparatus 400 is part of another system. In this case, the system is a motor vehicle 410, such as an autonomous vehicle. The apparatus 400 may form part of a Light Detection and Ranging (LIDAR) system of the motor vehicle 410.

[0163] like Figure 9A As shown, in use, the transmitter 424 may generate a first pulse signal, a second pulse signal, and a third pulse signal 428 before the target 422 is within the field of view 426 of the transmitter 424 .

[0164] When target 422 is in field of view 426 of emitter 424, e.g., in use, detector 430 may detect a portion of a first pulse signal reflected by target 422, a portion of a second pulse signal reflected by target 422, and a portion of a third pulse signal reflected by target 422, e.g., Figure 9B shown.

[0165] In this embodiment, the controller, the other controller, and the output device are provided by one or more controllers and output device 450 of the motor vehicle 410. However, it should be understood that in other embodiments, the controller, the other controller, and the output device may be located remotely from the motor vehicle 410. In such embodiments, the apparatus 400 may be configured to communicate with the controller, the other controller, and the output device via a communication module (e.g., a wireless communication module) of the motor vehicle 410. The communication module may be configured to communicate via a cellular communication network, Wi-Fi, Bluetooth, ZigBee, near field communication (NFC), IR, satellite communication, other Internet-enabled networks, and the like.

[0166] The term "target" may be taken to encompass objects, persons, locations, and / or structures, among others.

[0167] It should be understood that the devices and / or systems disclosed herein are not limited to use for two-dimensional or three-dimensional imaging or scanning and / or as part of a mobile device or motor vehicle. For example, the systems and / or devices disclosed herein can be applied to or integrated into many different devices, equipment, or systems, such as land, automotive, aerial, and mobile industries.

[0168] List of reference numerals:

[0169] 100 Methods of measuring distance

[0170] 102-160 Methods and Steps

[0171] f1 first frequency

[0172] f2 second frequency

[0173] f3 third frequency

[0174] RS1 Peak value of the first reference signal

[0175] RS2 Peak value of the second reference signal

[0176] RS3 Peak value of the third reference signal

[0177] RP1 Peak value of the reflected part of the first pulse signal

[0178] RP2 Peak value of the reflected part of the second pulse signal

[0179] RP3 Peak value of the reflected portion of the third pulse signal

[0180] DV Virtual difference between first / second and second / third virtual distances

[0181] VD1 First virtual distance

[0182] VD2 Second virtual distance

[0183] VD3 Third Virtual Distance

[0184] 220, 320 Systems for measuring distance to a target

[0185] 222, 322, 422 targets

[0186] 224, 324, 424 transmitters

[0187] 226, 426 field of view

[0188] 228, 328, 428 first, second and third pulse signals

[0189] 230, 330, 430 detectors

[0190] 232, 332, 432 Reflected parts of the first, second, and third pulse signals

[0191] 234, 334 controllers

[0192] 236 Cover

[0193] 238 Other parts of the reflection of the first, second and third pulse signals

[0194] 240 optical components

[0195] 242-pixel array

[0196] 244 pixels

[0197] 246 Another Controller

[0198] 248, 348 output devices

[0199] 400 Device for acquiring data

[0200] 405 Smartphone

[0201] 410 Motor Vehicles

[0202] 450 Controller, another controller and output device for a motor vehicle

[0203] Distance between EC emitter and cover part

[0204] R is the distance to the target

[0205] Embodiments of the present disclosure may also be implemented as instructions stored on a computer-readable medium, which may be read and executed by one or more processors. A computer-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device that may be provided in the form of a user device). For example, a computer-readable medium may include read-only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustic or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. In addition, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are merely for convenience, and that such actions are actually generated by a computing device, processor, controller, or other device that executes firmware, software, routines, instructions, etc.

[0206] To provide interaction with a user, the present disclosure may be implemented on a user device having a screen for displaying information to the user (e.g., a CRT (cathode ray tube), plasma, LED (light emitting diode), or LCD (liquid crystal display) monitor) and an input device through which the user can provide input to the computer (e.g., a keyboard, touch screen, mouse, trackball, etc.). Other types of devices may be used. For example, the feedback provided to the user may be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback; and input from the user may be received in any form, including sound, voice, or tactile input.

[0207] Although the present disclosure has been described in terms of the preferred embodiments described above, it should be understood that these embodiments are merely illustrative and that the claims are not limited to these embodiments. In light of this disclosure, those skilled in the art will be able to make modifications and substitutions that fall within the scope of the appended claims. Each feature disclosed or shown in this specification may be incorporated into the present disclosure, either alone or in any appropriate combination with any other features disclosed or shown herein.

Claims

1. A method for measuring a distance to a target, the method comprising: operating the transmitter to generate a first pulse signal and a second pulse signal in a field of view of the transmitter where a target may be present, the first pulse signal having a first pulse frequency and the second pulse signal having a second pulse frequency, the first pulse frequency being different from the second pulse frequency; operating a detector to detect a signal within a predetermined duration after generating the first pulse signal and within a predetermined duration after generating the second pulse signal; storing the detected signal in a memory spanning a period of the first pulse signal and a period of the second pulse signal respectively; using the detected signals to identify a portion of the first pulse signal reflected by the target and a portion of the second pulse signal reflected by the target; determining a first virtual distance based on a difference between a reference signal and detection of the portion of the first pulse signal reflected by the target; determining a second virtual distance based on a difference between the reference signal and detection of the portion of the second pulse signal reflected by the target; as well as The distance to the target is determined based on a virtual difference corresponding to a difference between the first virtual distance and the second virtual distance. 2 . The method of claim 1 , wherein the step of determining the distance to the target comprises determining a period difference corresponding to a difference between a period of the first pulse signal and a period of the second pulse signal.

3. The method of claim 2, wherein the step of determining the distance to the target comprises determining a cycle weight based on the virtual difference and the cycle difference, multiplying the cycle weight by the cycle of the first pulse signal and adding the first virtual distance.

4. The method of claim 2, wherein the step of determining the distance to the target comprises determining a cycle weight based on the virtual difference and the cycle difference, multiplying the cycle weight by the cycle of the second pulse signal and adding the second virtual distance.

5. The method according to any one of claims 2 to 4, wherein the memory comprises a plurality of intervals spanning a period of the first pulse signal and a period of the second pulse signal, respectively, and wherein each interval stores a value representing a detection signal detected in a predefined measurement window corresponding to a predefined distance or time. 6 . The method according to claim 5 , wherein the predefined measurement window of each interval corresponds to the period difference; a part of the period difference or a multiple of the period difference.

7. A method according to claim 5, wherein the first virtual distance is determined by calculating the number of intervals that separate a reference interval including a detection signal corresponding to a reference signal and a signal interval including a detection signal corresponding to the portion of the first pulse signal reflected by the target, and the second virtual distance is determined by calculating the number of intervals that separate the reference interval including a detection signal corresponding to the reference signal and a signal interval including a detection signal corresponding to the portion of the second pulse signal reflected by the target.

8. The method according to any one of claims 1 to 4, comprising: operating the transmitter to generate a third pulse signal in a field of view of the transmitter where a target may be present, the third pulse signal having a third pulse frequency that is different from the first pulse frequency and the second pulse frequency; operating a detector to detect a signal within a predetermined duration after generating the third pulse signal; storing the detected signal in a memory spanning a period of a third pulse signal; using the detected signal to identify a portion of a third pulse signal reflected by the target; determining at least two of a first virtual distance, a second virtual distance, and a third virtual distance, the third virtual distance being based on a difference between a reference signal and detection of the portion of the third pulse signal reflected by the target; as well as The distance to the target is determined based on a virtual difference corresponding to a difference between at least two of the first virtual distance, the second virtual distance, and the third virtual distance.

9. The method of claim 8, wherein the method comprises operating a transmitter to continuously generate a first pulse signal, a second pulse signal, and a third pulse signal.

10. The method of claim 8, wherein determining at least two of the first virtual distance, the second virtual distance, and the third virtual distance comprises selecting at least two of the first virtual distance, the second virtual distance, and the third virtual distance based on one or more of: the value and / or profile of the detection signal corresponding to the reference signal; a value and / or profile of a detection signal corresponding to the portion of the first pulse signal reflected by the target; a value and / or profile of a detection signal corresponding to the portion of the second pulse signal reflected by the target; and The value and / or profile of the detection signal corresponds to the portion of the third pulse signal reflected by the target.

11. The method of claim 8 , wherein the third virtual distance is determined by calculating the number of memory intervals that separate a reference interval including a detection signal corresponding to the reference signal and a signal interval including a detection signal corresponding to the portion of the third pulse signal reflected by the target.

12. The method of claim 8, wherein the step of determining the distance to the target comprises determining a period difference between at least two of a period of the first pulse signal, a period of the second pulse signal, and a period of the third pulse signal.

13. The method of claim 12, wherein the step of determining the distance to the target comprises determining a cycle weight based on the virtual difference and the cycle difference and at least one of: Multiplying the period weight by the period of the first pulse signal and adding the first virtual distance; Multiplying the period weight by the period of the second pulse signal and adding the second virtual distance; and The period weight is multiplied by the period of the third pulse signal and added to the third virtual distance.

14. The method according to any one of claims 1 to 4, wherein the reference signal is one of: a start signal; a synchronization signal; a signal stored in the first memory interval; a cover glass reflectivity; or a crosstalk signal.

15. A non-transitory computer-readable medium comprising a computer program comprising computer-readable instructions configured to cause a processor to perform the method according to any one of claims 1 to 14.

16. A device for measuring the distance to a target, the device comprising: a transmitter having a field of view in which a target may be present, the transmitter being configured to generate a first pulse signal and a second pulse signal in the field of view, the first pulse signal having a first pulse frequency and the second pulse signal having a second pulse frequency, the first pulse frequency being different from the second pulse frequency; a detector configured to detect a signal within a predetermined duration after the first pulse signal is generated and within a predetermined duration after the second pulse signal is generated; as well as a memory configured to store the detected signal, wherein the memory spans a period of the first pulse signal and a period of the second pulse signal respectively; as well as The controller is configured as: using the detected signals to identify a portion of the first pulse signal reflected by the target and a portion of the second pulse signal reflected by the target; determining a first virtual distance based on a difference between a reference signal and detection of the portion of the first pulse signal reflected by the target; determining a second virtual distance based on a difference between the reference signal and detection of the portion of the second pulse signal reflected by the target; as well as The distance to the target is determined based on a virtual difference corresponding to a difference between the first virtual distance and the second virtual distance.

17. An apparatus according to claim 16, wherein the detector comprises a pixel array, at least one or each pixel of the pixel array being configured to detect a signal corresponding to the portion of the first pulse signal reflected by the target and / or the portion of the second pulse signal reflected by the target.

18. The apparatus of claim 17, wherein the memory comprises a plurality of bins, and each bin is shared by a plurality of pixels of the pixel array.

19. The device according to any one of claims 16 to 18, wherein the memory spans only the period of the first pulse signal and / or only the period of the second pulse signal, respectively.

Images