Time-of-flight measurement circuit and related system, electronic device and method

Abstract

A time-of-flight measurement circuit, system, method and electronic device. The time-of-flight measurement circuit (100) includes a pixel array (102), a time-to-digital converter (104) and a controller (106). The pixel array (102) includes m rows×n columns of pixel units (P11-Pmn). The time-to-digital converter (104) includes n time-to-digital conversion units (L1-Ln). The controller (106) is used to control the pixel units (Pa1-Pan) in the ath row to be enabled in a first time window to receive a first reflected light pulse, and to be enabled in a second time window to receive a second reflected light pulse, and the time lengths of the first time window and the second time window are different.

Description

Technical Field

[0001] The present application relates to a measurement circuit, and more particularly to a time-of-flight measurement circuit and a related time-of-flight measurement system, an electronic device, and a time-of-flight measurement method. Background Art

[0002] Time-of-flight measurement technology includes direct time-of-flight measurement technology and indirect time-of-flight measurement technology. Direct time-of-flight measurement technology uses a light pulse to be emitted to the target object, and then measures the time interval between the reception time of the reflected light pulse reflected from the target object and the emission time of the light pulse. The flight time of light can be obtained, and the measured flight time is then used to calculate the depth information.

[0003] However, dust in the air will reflect and scatter light pulses, causing interference. The farther the object to be measured is, the more susceptible it is to interference. Therefore, how to reduce interference and improve accuracy has become one of the problems that need to be solved in this field. Summary of the invention

[0004] One of the purposes of the present application is to disclose a time-of-flight measurement circuit and a related time-of-flight measurement system, an electronic device and a time-of-flight measurement method to solve the above-mentioned problems.

[0005] One embodiment of the present application discloses a time-of-flight measurement circuit, which is used to measure the time interval between a first light pulse and a second light pulse emitted by a pulse generating unit and reflected back to the flight time measurement circuit after they start from a target object. The flight time measurement circuit comprises: a pixel array, comprising m rows×n columns of pixel units, wherein m and n are positive integers, and each of the pixel units comprises: a photosensitive sensor, which is used to generate a first trigger signal when receiving a first reflected light pulse reflected back to the flight time measurement circuit, and to generate a second trigger signal when receiving a second reflected light pulse reflected back to the flight time measurement circuit; a controller, which is coupled to the pixel array and the pulse generating unit, and is used to control the pulse generating unit to emit the first light pulse and the second light pulse, and the controller controls the pixel units in the ath row to be enabled in a first time window to receive the first reflected light pulse, and controls the pixel units in the ath row to be enabled in a second time window to receive the second A method for controlling the pixel units in the ath row to output the first trigger signal and the second trigger signal is provided. The method comprises: reflecting light pulses, and controlling each pixel unit in the ath row to output the first trigger signal and the second trigger signal through the ath row selection line among the m row selection lines, wherein the first trigger signal and the second trigger signal are sequentially transmitted from the output end of each pixel unit in the ath row through the pixel units in the (a+1)th row to the mth row, wherein a is any integer from 1 to m, and the time lengths of the first time window and the first time window are different; and a time-to-digital converter, comprising: n time-to-digital conversion units, including the first first time-to-digital conversion unit to the nth first time-to-digital conversion unit, correspondingly coupled to the n output ends of the pixel units in the first to nth columns of the mth row, wherein the n first time-to-digital conversion units respectively perform time-to-digital conversion based on the n first trigger signals and the n second trigger signals received from the output end of each pixel unit in the mth row, so as to obtain n first conversion results and n second conversion results correspondingly.

[0006] An embodiment of the present application discloses a time-of-flight measurement system, including: a pulse generating unit, used to emit a plurality of light pulses to a target object; and the above-mentioned time-of-flight measurement circuit.

[0007] An embodiment of the present application discloses an electronic device, including the above-mentioned time-of-flight measurement system.

[0008] An embodiment of the present application discloses a time-of-flight measurement method as described above, which is used to measure the time interval between a first light pulse and a second light pulse emitted by a pulse generating unit and reflected back to a target object after the pulse generating unit emits the first light pulse; the time-of-flight measurement method includes: controlling the pulse generating unit to emit the first light pulse; receiving a first reflected light pulse reflected from the first light pulse in a first time window and generating a first trigger signal; generating a first conversion result based on the first trigger signal; controlling the pulse generating unit to emit the second light pulse; receiving a second reflected light pulse reflected from the second light pulse in a second time window and generating a second trigger signal, wherein the time lengths of the first time window and the first time window are different; and generating a second conversion result based on the second trigger signal.

[0009] The time-of-flight measurement circuit of the present application utilizes different time windows to receive reflected light pulses to reduce the probability of interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. 1 is a schematic diagram of a first embodiment of a time-of-flight measurement circuit of the present application.

[0011] Figure 2 is a circuit diagram of a pixel unit in a pixel array.

[0012] Figure 3 FIG. 1 is a timing diagram of a time-of-flight measurement circuit of the present application performing time-of-flight measurement according to a first embodiment of the present invention.

[0013] Figure 4 This is a second embodiment of a timing diagram of the time-of-flight measurement circuit of the present application performing time-of-flight measurement.

[0014] Figure 5 This is a third embodiment of a timing diagram of the time-of-flight measurement circuit of the present application performing time-of-flight measurement.

[0015] Figure 6 FIG. 1 is a schematic diagram of a second embodiment of a time-of-flight measurement circuit of the present application. DETAILED DESCRIPTION

[0016] The following disclosure provides a variety of implementations or illustrations that can be used to implement different features of the present disclosure. The specific examples of components and configurations described below are used to simplify the present disclosure. As can be imagined, these descriptions are only illustrative and are not intended to limit the present disclosure. For example, in the description below, forming a first feature on or above a second feature may include certain embodiments in which the first and second features are directly in contact with each other; and may also include certain embodiments in which additional components are formed between the above-mentioned first and second features, so that the first and second features may not be in direct contact. In addition, the present disclosure may reuse component symbols and / or labels in multiple embodiments. Such repetition is based on the purpose of simplicity and clarity, and does not itself represent the relationship between the different embodiments and / or configurations discussed.

[0017] Furthermore, spatially relative terms such as "below," "below," "below," "above," and the like may be used herein to facilitate description of the relationship between one component or feature shown in the figure relative to another or more components or features. These spatially relative terms are intended to encompass a variety of different orientations of the device during use or operation in addition to the orientation shown in the figure. The device may be placed in other orientations (e.g., rotated 90 degrees or in other orientations), and these spatially relative descriptive terms should be interpreted accordingly.

[0018] Although the numerical ranges and parameters used to define the broader scope of the present application are approximate values, the relevant numerical values ​​in the specific embodiments have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual testing methods. Here, "about" generally refers to the actual value within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range. Alternatively, the term "about" means that the actual value falls within the acceptable standard error of the mean value, depending on the consideration of a person with ordinary knowledge in the technical field to which the present application belongs. It should be understood that, except for the experimental examples, or unless otherwise explicitly stated, all ranges, quantities, values ​​and percentages used herein (for example, to describe the amount of material used, the length of time, temperature, operating conditions, quantitative ratios and the like) are modified by "about". Therefore, unless otherwise stated to the contrary, the numerical parameters disclosed in this specification and the attached patent scope are all approximate values ​​and can be changed as needed. At least these numerical parameters should be understood as the number of significant digits indicated and the values ​​obtained by applying the general rounding method. Herein, numerical ranges are expressed from one endpoint to another endpoint or between two endpoints; unless otherwise stated, the numerical ranges described herein include the endpoints.

[0019] Figure 1This is a schematic diagram of a first embodiment of a time-of-flight measurement circuit of the present application. The time-of-flight measurement circuit 100 is used to measure the time interval of multiple light pulses emitted by a pulse generating unit (not shown in the figure) from the time of departure to the target object (not shown in the figure) and then reflected back to the time-of-flight measurement circuit 100, and uses direct time-of-flight measurement technology. For example, the pulse generating unit may include (but not limited to) a driving circuit and a light emitting unit. The driving circuit is used to drive the light emitting unit so that the light emitting unit intermittently emits light pulses LT. The light emitting unit may be (but not limited to) a semiconductor laser (also called a laser diode (LD)), a light emitting diode (LED) or other light emitting units that can generate light pulses. The light pulses generated by the semiconductor laser are coherent light, while the light pulses generated by the light emitting diode are incoherent light.

[0020] The time-of-flight measurement circuit 100 includes a pixel array 102, a time-to-digital converter 104, and a controller 106. Specifically, the pixel array 102 includes m rows×n columns of pixel units, where m and n are positive integers. For example, the pixel unit P11 represents the pixel unit in the first row and the first column of the pixel array 102, and the pixel unit Pmn represents the pixel unit in the mth row and the nth column of the pixel array 102. In the present embodiment, each pixel unit in the pixel array 102 is the same. Each pixel unit in the pixel array 102 includes a photosensitive sensor for generating a trigger signal when receiving a reflected light pulse LR reflected from the light pulse LT back to the time-of-flight measurement circuit 100. Generally speaking, the photosensitive sensor can be implemented by a single-photon avalanche diode, but the present application is not limited thereto.

[0021] Please refer to Figure 1 and Figure 2 , Figure 2 is a circuit diagram of pixel units P22, P23, P32 and P33 in the pixel array 102. It should be noted that each pixel unit in the pixel array 102 is identical, so Figure 2The illustrated pixel units P22, P23, P32 and P33 can also be used to illustrate other pixel units not illustrated. Taking the pixel unit P22 as an example, it can be seen that in addition to the avalanche diode D22, it further includes a switch T22, a current source I22, a buffer B22 and an AND gate A22, wherein the anode of the avalanche diode D22 is coupled to the reference voltage V1, and the switch T22 is coupled between the cathode of the avalanche diode D22 and the reference voltage V2. In this embodiment, the reference voltage V2 is a ground voltage. The current source I22 is coupled to the cathode of the avalanche diode D22, the buffer B22 is coupled to the cathode of the avalanche diode D22 and the first input terminal of the AND gate A22, and the second input terminal of the AND gate A22 is coupled to the row selection line to receive the signal RS2. Figure 2 In the embodiment, the switch T22 is implemented by an N-type transistor, and the gate of the N-type transistor receives a control signal E2 from the controller 106 to control the switch T22 to selectively conduct or not conduct. When the N-type transistor is conducted, the cathode of the avalanche diode D22 is limited to the reference voltage V2, that is, the avalanche diode D22 is kept in a reset state, so that the pixel unit P22 is disabled. At this time, even if reflected light is irradiated to the pixel unit P22, the charge sensed by the avalanche diode D22 cannot be read out; on the contrary, when the N-type transistor is not conducted, the cathode of the avalanche diode D22 is not limited to the reference voltage V2, that is, the pixel unit P22 is enabled, and the charge sensed by the avalanche diode D22 can be output as a trigger signal.

[0022] The controller 106 is coupled to the pixel array 102 and the pulse generating unit, and is used to control the pulse generating unit to emit a light pulse LT. The controller 106 enables or disables the selection of the m rows of pixel units correspondingly through m row selection lines. For example, the controller 106 sets RSa in the control signals RS1 to RSm to a high potential, and sets the signals other than RSa in the control signals RS1 to RSm to a low potential, so as to select the a-th row of pixel units Pa1 to Pan, where a is any integer from 1 to m. At this time, the trigger signals of each pixel unit Pa1 to Pan will be output from the output end of each pixel unit Pa1 to Pan to the input end of the next row of pixel units, that is, Figure 1 For example, it presents a downward vertical transmission, that is, when a is less than m, the trigger signal will be output from the output end of each pixel unit Pa1~Pan in the a-th row, and then pass through the pixel units in the (a+1)th row to the m-th row in sequence and output as the trigger signal TDCI1~TDCIn; when a is equal to m, the trigger signal will be directly output from the output end of each pixel unit Pm1~Pmn in the m-th row as the trigger signal TDCI1~TDCIn. The above is only for illustrative purposes, and in fact, more than one row of pixel units can be selected at the same time.

[0023] The present application is different from the general practice in that, before the controller 106 outputs the trigger signal of the pixel unit in the ath row through the row selection line, it is also necessary to control the time window in which the pixel unit in the ath row is enabled. Specifically, each of the pixel units in the ath row will only be enabled within the time window to receive the reflected light pulse LR to generate a trigger signal. Therefore, for each light pulse LT, there will be a corresponding time window to allow each of the pixel units in the ath row to sense the reflected light pulse LR. The time windows for different light pulses LT can have different specifications, and the variable specifications include the time length of the time window, or the time length between the starting point of the time window and the emission time point of the corresponding light pulse LT, or the time length between the end point of the time window and the emission time point of the corresponding light pulse LT. The details are described below.

[0024] In this embodiment, the controller 106 controls the time window of each pixel unit in the a-th row of pixel units Pa1-Pan through the control signal Ea. Figure 2 In the embodiment, when the controller 106 sets Ea in the control signals E1~Em to a low potential, the pixel units Pa1~Pan in the a-th row are enabled; when the controller 106 sets Ea in the control signals E1~Em to a high potential, the pixel units Pa1~Pan in the a-th row are disabled. In this embodiment, the pixel units Pa1~Pan in the a-th row are synchronously controlled to be enabled, that is, the timing of the time windows of the pixel units Pa1~Pan in the a-th row is the same. However, in some embodiments, they can also be controlled separately. In addition, it should be noted that the controller 106 will only control the time window of one row of pixel units at a time to perform sensing to generate trigger signals for multiple pixel units in the row of pixel units, and output the trigger signals for multiple pixel units in the row of pixel units through the row selection line.

[0025] The time-to-digital converter 104 includes a counter 1040 and n registers L1-Ln. The counter 1040 counts according to a reference clock and a signal TX. The signal TX is used to indicate the time point when the light pulse LT is emitted. The n registers L1-Ln include registers L1 to Ln. The registers L1-Ln are adjacent to each other in the layout diagram and are correspondingly coupled to the n output terminals of the pixel units Pm1-Pmn. The registers L1-Ln respectively store the count values ​​TDCO1-TDCOn of the counter 1040 based on the trigger signals TDCI1-TDCIn received from the n output terminals of the pixel units Pm1-Pmn to represent the measured flight time. That is, when the pixel unit Pm1 outputs the trigger signal TDCI1 to the register L1, the register L1 will temporarily store the count result of the counter 1040 at this time as the count value TDCO1. In this embodiment, the counter 1040 is coupled to the controller 106 . The controller 106 can transmit a signal TX to the counter 1040 , and can reset the counter 1040 through other signals (not shown in the figure), that is, clear the counter 1040 to zero.

[0026] Please also refer to Figure 1 and Figure 3 , Figure 3 The first embodiment of the timing diagram of the time-of-flight measurement circuit of the present application for time-of-flight measurement. The controller 106 controls the pulse generating unit to emit light pulses LT1 and LT2 at time points T1 and T3, respectively, and controls the counter 1040 to count from zero at the same time. The pixel units Pa1~Pan in the ath row receive the reflected light pulses LR1 and LR2 reflected from the target by the light pulses LT1 and LT2 at time points T2 and T4, respectively, wherein the difference between the time point T2 and the time point T1 is equal to the difference between the time point T4 and the time point T3, that is, the flight time of the reflected light pulses LR1 and LR2 reflected from the target is the same, that is, the flight distance of the reflected light pulses LR1 and LR2 reflected from the target to the time-of-flight measurement circuit 100 is the same. Since when the control signal Ea is 1, each pixel unit in the ath row of pixel units Pa1~Pan is disabled; when the control signal Ea is 0, each pixel unit in the ath row of pixel units Pa1~Pan is enabled, that is, when the control signal When the control signal Ea is 1, each pixel unit in the a-th row of pixel units Pa1-Pan is enabled; when the control signal Ea is 0, each pixel unit in the a-th row of pixel units Pa1-Pan is disabled. Figure 3 The inverted signal of the control signal Ea is shown in This allows people to more intuitively distinguish the range of the time window (i.e. the inverted signal is a time period of 1). Figure 3For the light pulses LT1 and LT2 , the control signal Ea given by the controller 106 is different, so the time window W1 corresponding to the light pulse LT1 and the time window W2 corresponding to the light pulse LT2 have different specifications.

[0027] Specifically, the time length TS1 of the time window W1 is greater than the time length TS2 of the time window W2. The time length between the start point of the time window W1 and the emission time point of the light pulse LT1 is 0; the time length between the start point of the time window W2 and the emission time point of the light pulse LT2 is TS3. The time length between the end point of the time window W1 and the emission time point of the light pulse LT1 is TS1; the time length between the end point of the time window W2 and the emission time point of the light pulse LT2 is also TS1.

[0028] In this embodiment, the time window W1 has a larger detection range than the time window W2, because the time window W1 starts at the emission time of the light pulse LT1, and the reflected light pulses reflected from both close-range and long-range targets can be detected. Figure 3 For example, no matter when LR1 appears in the TS1 interval, it can be detected, and the closer LR1 is to the starting point of LT1, it means that LR1 is reflected from a closer target object. The time window W2 starts TS3 after the emission time point of the light pulse LT2. In other words, the difference between time window W1 and time window W2 is that time window W2 cannot detect any signal reflected from the emission time point of the light pulse LT2 to TS3. In other words, time window W2 cannot detect the reflected light pulse reflected from the target object at a closer distance. Therefore, it can be said that time window W1 is a time window for global detection of long and short distances; time window W2 is a time window for long-distance detection. Figure 3 In the example, the distance between the target object and the time-of-flight measurement circuit 100 is far, and the reflected light pulses LR1 and LR2 caused by the light pulses LT1 and LT2 both fall within the time windows W1 and W2. The register L1 obtains the count values ​​TDCO1 of D1 and D2 respectively. Since the flight times of the reflected light pulses LR1 and LR2 are the same, D1 and D2 are of course also the same.

[0029] Since there are many possible errors and interferences in the actual time-of-flight measurement, in the time-of-flight measurement system of the present application, the same row of pixel units will be continuously made to receive multiple reflected light pulses, and the multiple results will be counted to obtain statistical results. For example, the pixel units Pa1~Pan in the ath row will continuously receive one hundred light pulses, which are one hundred reflected light pulses reflected from the target object. The controller 106 can adjust the ratio of the corresponding time window W1 and time window W2 for the one hundred reflected light pulses. For example, if the distance of the target object is set to be farther, 80 of the one hundred reflected light pulses can be allocated to the corresponding time window W2, and the remaining 20 can be allocated to the corresponding time window W1.

[0030] Please also refer to Figure 1 and Figure 4 , Figure 4 The second embodiment of the timing diagram of the time-of-flight measurement circuit of the present application for time-of-flight measurement. The controller 106 controls the pulse generating unit to emit light pulses LT1 and LT2 at time points T1 and T3, respectively, and controls the counter 1040 to count from zero at the same time. The pixel units Pa1 to Pan in the ath row receive the reflected light pulses LR1 and LR2 reflected from the target by the light pulses LT1 and LT2 at time points T2 and T4, respectively, wherein the difference between the time point T2 and the time point T1 is equal to the difference between the time point T4 and the time point T3, that is, the flight time of the reflected light pulses LR1 and LR2 reflected from the target is the same, that is, the flight distance of the reflected light pulses LR1 and LR2 reflected from the target to the time-of-flight measurement circuit 100 is the same. Figure 4 The specifications of the time windows W1 and W2 used and Figure 3 The time windows W1 and W2 used have the same specifications, but Figure 4 The distance between the target object and the flight time measurement circuit 100 is relatively large. Figure 3 The distance between the target object and the flight time measurement circuit 100 is close, so it can be seen Figure 4 The time when the reflected light pulse LR2 caused by the light pulse LT2 reaches the pixel units Pa1-Pan of the a-th row is earlier than the start time of the time window W2, resulting in no trigger signal TDC1 to the register L1 within the range of the time window W2. In the present application, if the trigger signal is not received at the end of the time window, the controller 106 can control the register to temporarily store the pre-designed value (the control circuit is not shown in FIG. Figure 1 ), for example, the preset count value is the maximum value that the register can store, so Figure 4 In the figure, TDCO1 for the light pulse LT2 is a pre-designed value DM. Thus, if the subsequent operation circuit (not shown in the figure) finds that the count value generated by the register is greater than a reasonable value, it can be understood that the object to be measured is at a close distance.

[0031] Please also refer to Figure 1 and Figure 5 , Figure 5 The third embodiment of the timing diagram of the time-of-flight measurement circuit of the present application for time-of-flight measurement. The controller 106 controls the pulse generating unit to emit light pulses LT1 and LT2 at time points T1 and T3, respectively, and controls the counter 1040 to count from zero at the same time. The pixel units Pa1 to Pan in the ath row receive the reflected light pulses LR1 and LR2 reflected from the target by the light pulses LT1 and LT2 at time points T2 and T4, respectively, wherein the difference between the time point T2 and the time point T1 is equal to the difference between the time point T4 and the time point T3, that is, the flight time of the reflected light pulses LR1 and LR2 reflected from the target is the same, that is, the flight distance of the reflected light pulses LR1 and LR2 reflected from the target to the time-of-flight measurement circuit 100 is the same. Figure 5 The specifications of the time windows W1 and W2 used and Figure 3 and Figure 4 The time windows W1 and W2 used have the same specifications, and Figure 5 The distance between the target object and the time-of-flight measurement circuit 100 and Figure 3 The distance between the target and the flight time measurement circuit 100 is the same, the difference is Figure 5 The dust interferes between the target object and the flight time measurement circuit 100, causing the light pulse LT1 to generate an interference light pulse LR1' and reach the pixel units Pa1~Pan in the a-th row at time point T2' before time point T2; and causing the light pulse LT2 to generate an interference light pulse LR2' and reach the pixel units Pa1~Pan in the a-th row at time point T4' before time point T4. The interference light pulse LR1' falls within the range of the time window W1, thereby causing the trigger signal TDC1 to be generated to the register L1, causing the register L1 to temporarily store an erroneous count value D1' instead of D1 corresponding to the reflected light pulse LR1. However, the interference light pulse LR2' falls outside the range of the time window W2, so the count value D2 temporarily stored in the register L1 correctly corresponds to the reflected light pulse LR2, avoiding interference.

[0032] In this embodiment, in order to improve the accuracy of long-distance detection and the contrast of long-distance and short-distance information, for a plurality of continuous light pulses LT, the controller 106 may use a time window for long-distance detection, such as time window W2, for most of them; and use a time window for long-distance and short-distance global detection, such as time window W1, for a few of them. In some embodiments, the controller 106 dynamically adjusts the ratio of the two time windows. In some embodiments, the controller 106 further uses a time window for short-distance detection.

[0033] In some embodiments, the time-to-digital converter 104 may be implemented using a delay line. Figure 6 . Figure 6FIG. 1 is a schematic diagram of a second embodiment of a time-of-flight measurement circuit of the present application. Figure 6 The time-of-flight measurement circuit 600 and Figure 1 The difference between the time-of-flight measurement circuit 100 is that Figure 6 The time-to-digital converter 604 of the time-of-flight measurement circuit 600 includes n time-to-digital conversion units 1041-104n adjacent to the m-th row of pixel units Pm1-Pmn. Specifically, the n time-to-digital conversion units 1041-104n are adjacent to and correspondingly coupled to the n output terminals of the pixel units Pm1-Pmn in the first to n-th columns of the m-th row. The n time-to-digital conversion units 1041-104n perform time-to-digital conversion based on the signal TX obtained from the controller 106 and the trigger signals TDCI1-TDCIn received from the output terminals of the m-th row of pixel units Pm1-Pmn, respectively, to obtain n conversion results TDCO1A-TDCOnA accordingly. The rest of the time-of-flight measurement circuit 600 is the same as the time-of-flight measurement circuit 100.

[0034] Compared with the counter 1040 Figure 1 Examples of Figure 6 The implementation method using delay lines can obtain a higher resolution than the counter 1040 , but the delay lines in the n time-to-digital conversion units 1041 - 104n may have problems of mutual mismatch and mutual signal coupling.

[0035] The present application also provides a time-of-flight measurement system, which includes the pulse generation unit and the time-of-flight measurement circuit 100 / 600. The present application also provides a chip, which includes the time-of-flight measurement circuit 100 / 600. The present application also provides an electronic device, which includes the chip or the time-of-flight measurement system. The electronic device can be any electronic device such as a smart phone, a personal digital assistant, a handheld computer system, a tablet computer or a digital camera.

[0036] The flight time measurement circuit 100 / 600 of the present application uses the change of the time window to adjust the range of the desired distance measurement. Generally speaking, there is more interference in long-distance distance measurement, so by adjusting the time window to eliminate the interference signal before the arrival of the real reflected light pulse, the accuracy of long-distance distance measurement can be enhanced. Since the accuracy of short-distance distance measurement is originally much higher than that of long-distance distance measurement, even if the proportion of the time window of short-distance distance measurement or global distance measurement is reduced, it will not have a great impact.

[0037] The above description briefly presents the features of certain embodiments of the present application, so that those with ordinary knowledge in the technical field to which the present application belongs can more fully understand the various aspects of the present disclosure. Those with ordinary knowledge in the technical field to which the present application belongs should understand that they can easily use the present disclosure as a basis to design or change other processes and structures to achieve the same purpose and / or achieve the same advantages as the embodiments described herein. Those with ordinary knowledge in the technical field to which the present application belongs should understand that these equal embodiments still belong to the spirit and scope of the present disclosure, and they can be variously changed, replaced and modified without departing from the spirit and scope of the present disclosure.

Claims

1. A time-of-flight measurement circuit, used to measure the time interval between a first light pulse and a second light pulse emitted by a pulse generating unit, starting from a target object and then reflected back to the time-of-flight measurement circuit, characterized in that: The time-of-flight measurement circuit comprises: a pixel array, comprising m rows×n columns of pixel units, wherein m and n are positive integers, and each of the pixel units comprises: a light-sensitive sensor, configured to generate a first trigger signal when receiving a first reflected light pulse reflected from the first light pulse to the time-of-flight measurement circuit, and to generate a second trigger signal when receiving a second reflected light pulse reflected from the second light pulse to the time-of-flight measurement circuit; a controller, coupled to the pixel array and the pulse generating unit, and used to control the pulse generating unit to emit the first light pulse and the second light pulse, and the controller controls the pixel units in the a-th row to be enabled to receive the first reflected light pulse in a first time window, and controls the pixel units in the a-th row to be enabled to receive the second reflected light pulse in a second time window, and controls each pixel unit in the a-th row to output the first trigger signal and the second trigger signal through the a-th row selection line among m row selection lines, and the first trigger signal and the second trigger signal are sequentially transmitted from the output end of each pixel unit in the a-th row through the pixel units in the (a+1)-th row to the m-th row, wherein a is any integer from 1 to m, and the time lengths of the first time window and the second time window are different; and Time to digital converter, including: n time-to-digital conversion units, including the first time-to-digital conversion unit to the nth time-to-digital conversion unit, are correspondingly coupled to the n output terminals of the pixel units in the first to nth columns of the mth row, and the n first time-to-digital conversion units respectively perform time-to-digital conversion based on the n first trigger signals and the n second trigger signals received from the output terminal of each of the pixel units in the mth row, so as to obtain n first conversion results and n second conversion results accordingly.

2. The time-of-flight measurement circuit as claimed in claim 1, wherein: There is a first time length between the start point of the first time window and the emission time point of the first light pulse, and there is a second time length between the start point of the second time window and the emission time point of the second light pulse, wherein the first time length is smaller than the second time length.

3. The time-of-flight measurement circuit as claimed in claim 2, wherein: There is a third time length between the end point of the first time window and the emission time point of the first light pulse, and there is a fourth time length between the end point of the second time window and the emission time point of the second light pulse, wherein the third time length is equal to the fourth time length.

4. The time-of-flight measurement circuit as claimed in claim 1, wherein: Each of the pixel units further comprises: The switch is coupled between one end of the photosensitive sensor and a first reference voltage, and the switch is controlled by the controller to be turned on to disable the pixel unit or not turned on to enable the pixel unit.

5. The time-of-flight measurement circuit as claimed in claim 4, wherein: Each of the pixel units further comprises: An AND gate has a first input terminal and a second input terminal, wherein the first input terminal is coupled to the one terminal of the photosensitive sensor, the second input terminal is coupled to one of the m row selection lines, and the output terminal of the AND gate generates an output result and is output from the output terminal of the pixel unit.

6. The time-of-flight measurement circuit as claimed in claim 5, wherein: The first reference voltage is a ground voltage. When the switch is turned on, the first input terminal of the AND gate is the ground voltage.

7. A time-of-flight measurement system, characterized in that: include: A pulse generating unit, used for emitting a plurality of light pulses to a target object; as well as A time-of-flight measurement circuit as claimed in any one of claims 1 to 6.

8. An electronic device, characterized in that: include: The time-of-flight measurement system as claimed in claim 7.

9. A method for measuring time of flight, for measuring the time interval between a first light pulse and a second light pulse emitted by a pulse generating unit, after they are emitted to a target object and reflected back to the time of flight measuring circuit, characterized in that: The time-of-flight measurement method comprises: controlling the pulse generating unit to emit the first light pulse; In a first time window, a first reflected light pulse reflected from the first light pulse is received by a pixel unit and a first trigger signal is generated; generating a first conversion result based on the first trigger signal; controlling the pulse generating unit to emit the second light pulse; In a second time window, receiving a second reflected light pulse reflected from the second light pulse through the pixel unit and generating a second trigger signal; and generating a second conversion result based on the second trigger signal, wherein the first light pulse falls within the range of the first time window, and the second light pulse does not fall within the range of the second time window, The time length of the first time window is greater than the time length of the second time window, and the time length between the end point of the first time window and the emission time point of the first light pulse is equal to the time length between the end point of the second time window and the emission time point of the second light pulse.

10. The time-of-flight measurement method according to claim 9, wherein: There is a first time length between the start point of the first time window and the emission time point of the first light pulse, and there is a second time length between the start point of the second time window and the emission time point of the second light pulse, wherein the first time length is smaller than the second time length.

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