Distance measuring device and calibration method

Abstract

A distance measuring device according to the present invention includes: a light emitting unit that emits light; a light receiving sensor that receives light emitted by the light emitting unit and reflected by a target object; and a calibration calculation unit that performs the calculation process as a calibration calculation process for finding correction parameters for distance information calculated by an indirect ToF method based on a light signal received from the light receiving sensor, using a light signal received from the light receiving sensor when the light emitting unit transmits light at a first light transmission frequency and a light signal received from the light receiving sensor when the light emitting unit transmits light at a second light transmission frequency different from the first light transmission frequency.

Description

Technical Field

[0001] The present technology relates to a distance measuring device and a calibration method thereof, and particularly to a technology for obtaining correction parameters for distance information calculated by an indirect ToF method. Background Art

[0002] Various distance measurement techniques for measuring the distance to a target object are known, and in recent years, for example, a distance measurement technique based on a time-of-flight (ToF) method has attracted attention.

[0003] As the ToF method, a direct ToF method and an indirect ToF method are known.

[0004] Among these ToF methods, in the indirect ToF method, distance measurement is performed by emitting sinusoidal wave light and receiving light struck and reflected by a target object.

[0005] In this case, the light-receiving sensor has pixels arranged in a two-dimensional array. Each pixel has a light-receiving element and can capture light. Each pixel then receives light in sync with the phase of the emitted light, determining the phase and amplitude of the received sine wave. Note that the phase is based on the emitted sine wave.

[0006] The phase of each pixel corresponds to the time it takes for light from the light emitting unit to enter the sensor after being reflected by the target object. Therefore, by dividing the phase by 2πf, further multiplying by the speed of light (hereinafter referred to as "one-two"), and dividing by 2, the distance to the distance measurement target point (distance measurement point) projected on the pixel can be calculated. Note that f represents the frequency of the sine wave of the emitted light.

[0007] Here, in indirect ToF, the actual emitted light is not strictly sinusoidal (e.g., a square wave). Therefore, the distance calculated by the above calculation is not a strictly correct distance. The element of distance error caused by the fact that the emitted light is not a sinusoidal wave in this way is called "cyclic error."

[0008] If the cyclic error can be obtained, the corrected distance can be obtained by correcting the distance using the cyclic error.

[0009] The following non-patent document 1 discloses a technique for correcting the distance using a correction parameter as the cyclic error.

[0010] Reference List

[0011] Patent Literature

[0012] Non-patent literature 1: Fuchs, S., May, S.: Calibration and registration for precise surface reconstruction with time-of-flight cameras. Int. J. Intell. Syst. Technol. Appl. 5, 274-284 (2008) Summary of the Invention

[0013] Problems to be solved by the present invention

[0014] Conventionally, calibration to obtain correction parameters for cyclic errors is performed at a known distance to a target object, requiring the target object to be precisely positioned at that distance. For this reason, conventional calibration is performed using precise equipment before product shipment, making it difficult to perform calibration in actual use environments after shipment.

[0015] The present technology has been proposed in view of the above circumstances, and an object thereof is to enable calibration for obtaining correction parameters for distance information calculated by an indirect ToF method to be performed in an actual usage environment of a device.

[0016] Solution to the problem

[0017] A first distance measuring device according to the present technology includes: a light-emitting unit that emits light; a light-receiving sensor that receives light emitted from the light-emitting unit and reflected by a target object; and a calibration calculation unit that performs calculation processing as a calibration calculation processing for obtaining correction parameters for distance information calculated by an indirect ToF method based on a light-receiving signal of the light-receiving sensor, using a light-receiving signal of the light-receiving sensor when the light-emitting unit transmits light at a first light-transmitting frequency and a light-receiving signal of the light-receiving sensor when the light-emitting unit transmits light at a second light-transmitting frequency different from the first light-transmitting frequency.

[0018] By using multiple light emission frequencies, correction parameters can be obtained even if the distance to the target object is uncertain.

[0019] In the first distance measuring device according to the present technology described above, a configuration can be conceived in which the calibration calculation unit performs calculation processing based on a phase difference between light transmission and light reception, the phase difference being detected from a light reception signal, and obtains a correction parameter.

[0020] Therefore, it is possible to obtain appropriate correction parameters corresponding to the case where distance measurement is performed by the indirect ToF method which is a phase difference method.

[0021] In the first distance measurement device according to the present technology described above, a configuration can be conceived in which the calibration calculation unit performs uncertainty elimination processing of eliminating uncertainty in units of 2π with respect to the phase difference.

[0022] Therefore, the calculation process of the correction parameter can be performed using the phase difference from which the uncertainty in units of 2π has been eliminated.

[0023] In the first distance measuring device according to the present technology described above, a configuration can be conceived in which, when the calibration calculation unit performs light transmission at the lowest light transmission frequency among the light transmission frequencies of the light transmission units used for calibration calculation processing, among phase differences detected from the light reception signals, the phase difference detected from the light reception signals having an amplitude equal to or greater than a predetermined value is determined as the phase difference corresponding to the lowest light transmission frequency, and based on the determined phase difference corresponding to the lowest light transmission frequency, a process of eliminating uncertainty associated with phase differences corresponding to light transmission frequencies other than the lowest light transmission frequency is performed.

[0024] In relation to the phase difference corresponding to the lowest light emission frequency, as described above, by selecting the phase difference detected from the light receiving signal having an amplitude equal to or greater than a predetermined value, uncertainty in units of 2π can be eliminated, and in relation to the phase difference corresponding to another one of the light emission frequencies other than the lowest light emission frequency, a true phase difference can be specified based on the phase difference corresponding to the lowest light emission frequency in which uncertainty is eliminated in this manner (i.e., uncertainty in units of 2π can be eliminated).

[0025] In the first distance measurement device according to the present technology described above, a configuration can be conceived in which the calibration calculation unit performs calibration calculation processing based on an elapsed time from a previous execution.

[0026] Therefore, even in the event that the correction parameter deviates from the true value over time, the correction parameter can be recalibrated.

[0027] In the first distance measurement device according to the present technology described above, a configuration can be conceived in which, when a distance measurement instruction is given during execution of the calibration calculation process, the calibration calculation unit interrupts the calibration calculation process and performs processing for distance measurement.

[0028] Therefore, even in the case where the calibration calculation process is executed in the background, the calibration calculation process is interrupted when a distance measurement instruction is given, and the distance measurement operation is performed according to the instruction.

[0029] A first calibration method according to the present technology is a calibration method in a distance measuring device, which includes: a light emitting unit that emits light; and a light receiving sensor that receives light emitted from the light emitting unit and reflected by a target object, and performs distance measurement by an indirect ToF method based on a light receiving signal of the light receiving sensor, the calibration method including: calibration calculation processing as a correction parameter for obtaining distance information calculated by the indirect ToF method, using a light receiving signal of the light receiving sensor when the light emitting unit emits light at a first light transmitting frequency, and a light receiving signal of the light receiving sensor when the light emitting unit emits light at a second light transmitting frequency different from the first light transmitting frequency, to perform calculation processing.

[0030] Also, by this first calibration method, an operation similar to that of the first distance measuring device according to the present technology described above can be obtained.

[0031] A second distance measuring device according to the present technology includes: a light emitting unit that emits light; a light receiving sensor that receives, by a plurality of pixels, the light emitted from the light emitting unit and reflected by a target object; and a calibration calculation unit that performs calculation processing using a condition that corresponding distance measurement points projected onto the plurality of pixels are in a specific positional relationship with each other as calibration calculation processing for obtaining correction parameters for distance information calculated by an indirect ToF method based on a light reception signal of the light receiving sensor.

[0032] As described above, by using the condition that the distance measurement points have a specific positional relationship with each other, correction parameters can be obtained even if the distance to the target object is uncertain.

[0033] In the second distance measurement device according to the present technology described above, a configuration is conceivable in which the calibration calculation unit performs calculation processing using a condition that the distance measurement points are located on an object having a known shape with each other as the calibration calculation processing.

[0034] If the distance measurement points are located on an object having a known shape relative to each other, the positional relationship between the distance measurement points can be defined as a mathematical expression based on the known shape.

[0035] In the above-mentioned second distance measuring device according to the present technology, a configuration can be envisioned in which the calibration calculation unit performs calculation processing using, as calibration calculation processing, a light reception signal of the light reception sensor when the light transmission unit transmits light at a first light transmission frequency, and a light reception signal of the light reception sensor when the light transmission unit transmits light at a second light transmission frequency different from the first light transmission frequency.

[0036] That is, as the calibration calculation process, the calculation process is performed using a plurality of light emission frequencies under the condition that the respective distance measurement points are in a specific positional relationship with each other, and thus the number of equations of unknown numbers can be increased.

[0037] In the second distance measuring device according to the present technology described above, a configuration can be conceived in which the calibration calculation unit performs calculation processing based on a phase difference between light emission and light reception, the phase difference being detected based on a light reception signal, and obtains a correction parameter.

[0038] Therefore, it is possible to obtain appropriate correction parameters corresponding to the case where distance measurement is performed by the indirect ToF method which is a phase difference method.

[0039] In the second distance measurement device according to the present technology described above, a configuration can be conceived in which the calibration calculation unit performs uncertainty elimination processing of eliminating uncertainty in units of 2π with respect to the phase difference.

[0040] Therefore, the calculation process of the correction parameter can be performed using the phase difference from which the uncertainty in units of 2π has been eliminated.

[0041] In the second distance measuring device according to the present technology described above, a configuration can be conceived in which, when the calibration calculation unit performs light transmission at the lowest light transmission frequency among the light transmission frequencies of the light transmission units used for calibration calculation processing, among phase differences detected from the light reception signals, the phase difference detected from the light reception signals having an amplitude equal to or greater than a predetermined value is determined as the phase difference corresponding to the lowest light transmission frequency, and based on the determined phase difference corresponding to the lowest light transmission frequency, a process of eliminating uncertainty associated with the phase difference corresponding to another light transmission frequency other than the lowest light transmission frequency is performed.

[0042] In relation to the phase difference corresponding to the lowest light emission frequency, as described above, by selecting the phase difference detected from the light receiving signal having an amplitude equal to or greater than a predetermined value, uncertainty in units of 2π can be eliminated, and in relation to the phase difference corresponding to another one of the light emission frequencies other than the lowest light emission frequency, a true phase difference can be specified based on the phase difference corresponding to the lowest light emission frequency in which uncertainty is eliminated in this manner (i.e., uncertainty in units of 2π can be eliminated).

[0043] In the second distance measurement device according to the present technology described above, a configuration can be conceived in which: a guide display processing unit is further included that performs display processing of a guide image that guides composition for satisfying the condition that the distance measurement points are in a specific positional relationship with each other.

[0044] Therefore, it is possible to increase the possibility of calibrating the correction parameters under the condition that the distance measurement points are in a specific positional relationship with each other.

[0045] A second calibration method according to the present technology is a calibration method in a distance measuring device that uses a light-emitting unit that emits light and a light-receiving sensor that receives light emitted from the light-emitting unit and reflected by a target object by a plurality of pixels, and performs distance measurement by an indirect ToF method based on a light-receiving signal of the light-receiving sensor, the calibration method including: calibration calculation processing as a correction parameter for obtaining distance information calculated by the indirect ToF method, the calculation processing being performed using a condition that each of the distance measurement points projected onto the plurality of pixels is in a specific positional relationship with each other.

[0046] Also, by this second calibration method, an operation similar to that of the second distance measuring device according to the present technology described above can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a block diagram for describing an internal configuration example of a distance measurement device as a first embodiment according to the present technology.

[0048] Figure 2 This is an illustration of 2π uncertainty.

[0049] Figure 3 4 is a flowchart of the calibration calculation process as the first embodiment.

[0050] Figure 4 is a flowchart of the 2π uncertainty elimination process.

[0051] Figure 5 is a flowchart of processing executed by the control unit in the second embodiment.

[0052] Figure 6 is a flowchart of the calibration calculation process in the second embodiment.

[0053] Figure 7 is a block diagram for describing an internal configuration example of a distance measurement device as a third embodiment.

[0054] Figure 8 is a diagram schematically showing a state of the distance measuring device when calibration is performed according to the third embodiment.

[0055] Figure 9 It is an explanatory diagram of a planar imaging area.

[0056] Figure 10 : is a diagram for describing an example of a guide display at the time of calibration in the third embodiment.

[0057] Figure 11is a flowchart showing the flow of processing when calibration is performed as the third embodiment.

[0058] Figure 12 is a flowchart of the calibration process in the third embodiment. DETAILED DESCRIPTION

[0059] Hereinafter, embodiments according to the present technology will be described in the following order with reference to the drawings.

[0060] <1. First embodiment>

[0061] [1-1. Configuration of distance measuring device]

[0062] [1-2.21 Uncertainty]

[0063] [1-3. Calibration method as first embodiment]

[0064] <2. Second embodiment>

[0065] <3. Third embodiment>

[0066] <4. Modifications>

[0067] <5. Overview of Examples>

[0068] <6. This technology>

[0069] <1. First embodiment>

[0070] [1-1. Structure of distance measuring device]

[0071] Figure 1 : is a block diagram for describing an internal configuration example of a distance measurement device 1 as a first embodiment according to the present technology.

[0072] The distance measuring device 1 performs distance measurement using an indirect time-of-flight (ToF) method. The indirect ToF method is a distance measurement method that calculates the distance to the target object Ob based on the phase difference between the illumination light Ls associated with the target object Ob and the reflected light Lr obtained by reflecting the illumination light Ls from the target object Ob.

[0073] In this example, the distance measurement device 1 is configured as a portable information processing device such as a smartphone or a tablet terminal having a distance measurement function by an indirect ToF method.

[0074] As shown in the figure, the distance measuring device 1 includes a light emitting unit 2 , a sensor unit 3 , a lens 4 , a phase difference detecting unit 5 , a calculating unit 6 , an amplitude detecting unit 7 , a control unit 8 , a memory unit 9 , a display unit 10 , and an operating unit 11 .

[0075] The light emitting unit 2 includes one or more light emitting elements as a light source, and emits irradiation light Ls toward the target object Ob. In this example, the light emitting unit 2 emits infrared light having a wavelength in the range of 780 nm to 1000 nm as the irradiation light Ls.

[0076] In the indirect ToF method, light whose intensity is modulated so that the intensity changes in a predetermined cycle is used as the illumination light Ls. Specifically, in this example, the illumination light Ls is repeatedly emitted according to the clock CLK. In this case, the illumination light Ls is not a strict sine wave, but a roughly sine wave.

[0077] In this example, the frequency of the clock CLK is variable, and thus the light emission frequency of the illumination light Ls is also variable. The light emission frequency of the illumination light Ls can be changed within a predetermined frequency range with a base frequency of, for example, 10 MHz (megahertz).

[0078] The sensor unit 3 has a plurality of pixels arranged in a two-dimensional array. Each pixel includes a light-receiving element, such as a photodiode, for example, and receives reflected light Lr. A lens 4 is attached to the front surface of the sensor unit 3, and the reflected light Lr is converged by the lens 4 and effectively received by each pixel in the sensor unit 3.

[0079] The clock CLK is supplied to the sensor unit 3 as a timing signal of the light receiving operation, whereby the sensor unit 3 performs the light receiving operation in synchronization with the cycle of the illumination light Ls emitted from the light emitting unit 2 .

[0080] The sensor unit 3 accumulates data over tens of thousands of cycles related to the period of the irradiation light Ls and outputs data proportional to the accumulated amount of received light. Note that this accumulation is done because, although the amount of light received is small at a time, the amount of received light can be accumulated over tens of thousands of cycles, allowing for the acquisition of a large amount of data. Therefore, distance measurement is performed at intervals of tens of thousands of cycles within the light emission period of the irradiation light Ls.

[0081] The phase difference detection unit 5 detects a phase difference corresponding to the time difference from the light emission timing of the irradiation light Ls to the light reception timing of the reflected light Lr using data proportional to the accumulated light amount of the received light output from each pixel of the sensor unit 3. This phase difference is proportional to the distance to the target object Ob.

[0082] Note that, although not shown, in the indirect ToF method, two floating diffusions (FDs) are set for each light-receiving element in each pixel of the sensor unit 3, and the accumulated charge of the light-receiving element during one light emission cycle of the irradiation light Ls is distributed to these FDs. Then, each pixel outputs data proportional to the charge accumulated in these FDs during a period of tens of thousands of light emission cycles of the irradiation light Ls. In this way, the phase difference detection unit 5 detects the phase difference based on the data of each FD output from each pixel.

[0083] The calculation unit 6 calculates the distance of each pixel based on the phase difference detected for each pixel by the phase difference detection unit 5. Specifically, the distance of each pixel is calculated by multiplying the phase difference detected by the phase difference detection unit 5 by {c ÷ (4πf)}. Note that f is the light emission frequency (frequency of the sine wave) of the irradiation light Ls.

[0084] Hereinafter, information indicating the distance of each pixel obtained by the calculation unit 6 is referred to as a “range image”.

[0085] The amplitude detection unit 7 detects the amplitude of the received light reflected light Lr (sine wave) using data proportional to the accumulated light amount of the received light output from each pixel of the sensor unit 3 .

[0086] The control unit 8 includes a microcomputer composed of, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and controls the entire distance measuring device 1 by executing, for example, a program stored in the ROM.

[0087] For example, the control unit 8 performs operation control of the light emitting unit 2 including control of the light emission frequency of the irradiation light Ls, control of the light receiving operation of the sensor unit 3 , and execution control of the distance calculation process of the calculation unit 6 .

[0088] Furthermore, the control unit 8 performs control of a display operation of the display unit 10 and various types of processing according to operation input information from the operation unit 11 .

[0089] The display unit 10 is a display device capable of displaying images, such as a liquid crystal display or an organic electroluminescence (EL) display, and displays various types of information according to instructions from the control unit 8 .

[0090] The operation unit 11 comprehensively represents various operating elements such as buttons, keys, and a touch panel provided in the distance measurement device 1. The operation unit 11 outputs operation input information based on the user's operation input to the control unit 8. The control unit 8 performs processing based on the operation input information to implement the operation of the distance measurement device 1 based on the user's operation input.

[0091] The memory unit 9 includes, for example, a nonvolatile memory and is used to store various data processed by the control unit 8 and the calculation unit 6. In this embodiment, information of correction parameters for correcting a distance described later is stored in the memory unit 9 as parameter information 9a, and this will be described again.

[0092] The control unit 8 has a function as a calibration calculation unit 8a. The correction parameter used for distance correction is obtained by the function as the calibration calculation unit 8a, and this point will be described again later.

[0093] [1-2.21 Uncertainty]

[0094] Will refer to Figure 2 Describes the uncertainty of the phase difference in units of 2π (hereinafter referred to as "2π uncertainty").

[0095] Figure 2 A shows temporal changes in the emission intensity of the illumination light Ls (sine wave) emitted from the light emitting unit 2 . Figure 2 B shows temporal changes in the received light intensity of the reflected light Lr from the target object Ob. Figure 2 A and Figure 2 The phase difference between B (denoted by δ) is proportional to the distance between the distance measuring device 1 and the target object Ob.

[0096] Here, when the target object Ob is located farther away, the phase difference may be further shifted by 2π (see Figure 2 C) or can be offset by 4π (see Figure 2 D) Furthermore, deviations of 6π or more are also conceivable.

[0097] Since the phase difference detection unit 5 detects only the phase difference, it cannot distinguish Figure 2 B. Figure 2 C and Figure 2 D. That is, it is uncertain which of the phase differences of δ + 2sπ (where s is an integer of 0 or greater) it is. For the distance description, it is uncertain which of {(δ + 2sπ) × × 2(4πf)} (where s is an integer of 0 or greater) it is. This fact that it is impossible to determine which of the phase differences of δ + 2sπ it is is referred to herein as 2π uncertainty.

[0098] Note that in the indirect ToF method, a value of s = 0 is generally output. That is, δ × (4πf) is output as the distance. Here, δ is a value greater than or equal to 0 and less than 2π.

[0099] [1-3. Calibration method as first embodiment]

[0100] Here, as described above, since the irradiation light Ls is not a perfect sine wave in practice, correction is required in the calculation of the distance in the calculation unit 6. The parameters used for the calculation correction are stored as parameter information 9a in the memory unit 9. Therefore, the calculation unit 6 does not simply "multiply the phase difference by {c ÷ (4πf)}" but performs complex calculations. This "complex calculation" will be described below.

[0101] As parameter information 9a, values ​​A1 to An and B1 to Bn, ag, bg, and cg are stored. These are parameters for performing correction calculations. Note that N is a predetermined value, for example, N=20.

[0102] As described in Chapter 4 of Non-Patent Document 1, it is necessary to correct the cyclic error and the signal propagation delay.

[0103] Since the cyclic error is periodic, it can be represented by a trigonometric function. Therefore, the component of the cyclic error at a frequency n times the phase observed in the sensor unit 3 is An, and the phase shift at this frequency is represented by Bn. Here, n can take values ​​from 1 to N.

[0104] The signal propagation delay mainly considers the signal propagation delay of each pixel in the sensor unit 3. The signal propagation delay of each pixel is caused by a time difference until charge reset is performed depending on the pixel position.

[0105] Signal propagation delay is linear with respect to pixel position, as described in Chapter 4 of Non-Patent Document 1. Therefore, the phase shift across the entire pixel is represented by ag, the tilt of the delay relative to the pixel position in the row direction (horizontal direction) is represented by bg, and the tilt of the delay relative to the pixel position in the column direction (vertical direction) is represented by cg. Furthermore, in Chapter 4 of Non-Patent Document 1, ag is represented as b0, bg as b1, and cg as b2.

[0106] Here, the number of pixels of the sensor unit 3 is represented by U pixels, and the pixel position of the sensor unit 3 is represented by (u, v). In this case, u=1 to U and v=1 to V.

[0107] Furthermore, the phase difference observed at the pixel position (u, v) (ie, the phase difference calculated by the phase difference detection unit 5 ) is represented by θ(u, v).

[0108] The distance L(u, v) corresponding to the pixel position (u, v) is calculated by the following [Expression 1] including An, Bn, ag, bg, and cg as the above-mentioned correction parameters.

[0109] [Expression 1]

[0110]

[0111] where φ (u，v) =θ (u，v) +a g +b g u+c g v

[0112] [Expression 1]

[0113] That is, the calculation unit 6 performs the calculation described in [Expression 1] using the parameters A1 to An, B1 to Bn, and ag, bg, and cg, rather than simply “multiplying the phase difference θ by {c ÷ (4πf)}.” The calculation result, L(u, v), is obtained as a distance measurement result relative to the pixel position (u, v).

[0114] Note that the parameters A1 to An and B1 to Bn, ag, bg, and cg are obtained by measuring using an accurate device at the time of product shipment. The obtained values ​​are pre-stored in the memory unit 9 as parameter information 9a.

[0115] Here, due to long-term changes, there is a possibility that the values ​​of parameters A1 to An and B1 to Bn may deviate from the true values ​​and become inappropriate values. Therefore, even if the user is using the distance measuring device 1, calibration can be performed to update the parameters A1 to An and B1 to Bn stored as parameter information 9a. For this purpose, it is desirable to be able to easily perform calibration without using an accurate device (which can calculate the values ​​of parameters A1 to An and B1 to Bn).

[0116] It should be noted that, of course, calibration can be performed using the method of the embodiment when the product is shipped, and the parameters A1 to An and B1 to Bn as the calibration results can be stored and shipped as parameter information 9a. In this case, the advantage of using the method of the embodiment is that calibration can be performed without installing precise equipment in the factory.

[0117] Will refer to Figure 3 The flowchart of FIG. 1 describes the calibration calculation process as in the first embodiment. For example, the process is Figure 1 The processing of the calibration calculation unit 8a shown in FIG. 1 is executed by the control unit 8 based on a program stored in a predetermined storage device such as the above-mentioned ROM.

[0118] The amplitude detected by the amplitude detection unit 7 and the phase difference detected by the phase difference detection unit 5 are input to the calibration calculation unit 8a. Then, the values ​​of the parameters A1 to An and B1 to Bn are calculated by the calibration calculation unit 8a (described later) and stored in the storage unit 9 as parameter information 9a (overwriting the values ​​of the parameters A1 to An and B1 to Bn). Therefore, the appropriate values ​​of the parameters A1 to An and B1 to Bn are always stored as the parameter information 9a, and when the user causes the distance measurement device 1 to perform distance measurement, a correct distance measurement result can be obtained by [Expression 1].

[0119] Note that it is conceivable that, for example, when the user turns on the power of the distance measurement device 1 , the calculation by the calibration calculation unit 8 a and the rewriting processing on the memory unit 9 are automatically performed in response to establishment of a predetermined trigger condition.

[0120] This embodiment is characterized in that a plurality of frequencies f (light emission frequencies) are used in calibration. Specifically, T (T is a natural number of 2 or more) frequencies f are used. In the following, a frequency is represented by f(t). Here, t is 1 to T. For example, f(1) = 10 MHz, f(2) = 11 MHz, f(3) = 12 MHz, and so on. Note that it is assumed that the frequency f(1) with t = 1 is the lowest frequency. Regarding T, for example, T = 15.

[0121] Here, the cyclic error and the signal propagation delay depend on t. That is, for each t, ​​the cyclic error and the signal propagation delay are stored as correction parameters in the storage unit 9 as parameter information 9a.

[0122] Hereinafter, parameters of the cyclic error at t are denoted by A1(t) to An(t) and B1(t) to Bn(t).

[0123] Furthermore, it is assumed that the parameters a(t), b(t), and c(t) of the signal propagation delay at each frequency f(t) are measured at the time of shipment from the factory. It is assumed that the parameters a(t), b(t), and c(t) of the signal propagation delay measured in advance are also stored as parameter information 9a in the memory unit 9. Furthermore, in Chapter 4 of Non-Patent Document 1, a(t) is described as b0, b(t) as b1, and c(t) as b2.

[0124] Will describe Figure 3 processing.

[0125] First, in step S101 , the calibration calculation unit 8 a sets h = 1. Then, the process proceeds to step S102 .

[0126] In step S102 , the calibration calculation unit 8 a determines whether h is equal to or smaller than H. If it is equal to or smaller than H, the process proceeds to step S103 .

[0127] Here, H is the number of measurements used for calibration (predetermined value), for example, H = 40. In addition, because measurements are performed at intervals of a predetermined time k, calibration requires H intervals of time. Only H different target objects (different distances) will be measured.

[0128] In step S103 , the calibration calculation unit 8 a sets t = 1. Then, the process proceeds to step S104 .

[0129] In step S104 , the calibration calculation unit 8 a determines whether t is equal to or smaller than T. If equal to or smaller than T, the process proceeds to step S105 .

[0130] In step S105 , the calibration calculation unit 8 a controls the execution of light emission / reception at the frequency f(t). That is, the light emitting unit 2 emits the irradiation light Ls at the frequency f(t), and the sensor unit 3 receives the reflected light Lr.

[0131] In step S106 following step S105 , the calibration calculation unit 8 a causes the phase difference detection unit 5 to detect the phase difference at each pixel position (u, v) and acquires the phase difference as the phase difference p(h, t, u, v). The process then proceeds to step S107 .

[0132] In step S107 , in order to obtain data of the next frequency f, the calibration calculation unit 8 a adds 1 to t and returns to step S104 .

[0133] In the event that t is determined to be not less than T in step S104 , that is, in the event that the phase difference p(h, t, u, v) is acquired for each light emission frequency of t=1 to T in step S106 , the calibration calculation unit 8 a proceeds to step S108 .

[0134] In step S108, the calibration calculation unit 8a discards the phase differences p(h, t, u, v) based on their amplitudes. Specifically, if any of the "T amplitudes of the light-receiving signal at frequencies f(t)" at each pixel position (u, v) is less than a predetermined value, the phase difference p(h, t, u, v) (the sum T of t = 1 to T) is discarded. In other words, in step S108, if the amplitudes at all frequencies f(t) (t = 1 to T) at all pixel positions (u, v) are equal to or greater than the predetermined value, no processing is performed.

[0135] A small amplitude means that the reflected light from the target object Ob is small, which reduces the reliability of the measurement data. Therefore, such data is discarded.

[0136] Here, in the case where data discarding is performed in step S108 , all measurements of the h-th phase difference p (h, t, u, v) become invalid, and therefore, in this example, when data discarding is performed, h=h−1 is performed.

[0137] In step S109 following step S108 , the calibration calculation unit 8 a waits for a predetermined time k for the next measurement (the (h+1)th measurement), and then increments h by 1 in step S110 , returning to the previous step S102 .

[0138] Thus, the phase difference p (h, t, u, v) is measured H times for each of the T light emission frequencies.

[0139] If it is determined in step S102 that h is not equal to or less than H, the calibration calculation unit 8a proceeds to step S111 and performs 2π uncertainty elimination processing. Specifically, in step S111, a process of eliminating the 2π uncertainty of the phase difference p(h, t, u, v) is performed for each h, each t, ​​and each (u, v). The phase difference from which the 2π uncertainty is eliminated is represented by θ(h, t, u, v).

[0140] It should be noted that the details of the 2π uncertainty elimination process in step S111 will be described later (see Figure 4 ).

[0141] In step S112 following step S111, the calibration calculation unit 8a obtains parameters of the cyclic error (parameters A1(t) to An(t) and B1(t) to Bn(t)) that satisfy [Expression 3] described later. The obtained parameters are stored in the memory unit 9 as parameter information 9a (covering the values ​​of the parameters A1(t) to An(t) and B1(t) to Bn(t)).

[0142] The calibration calculation unit 8a terminates execution of the process in response to step S112. Figure 3 A series of processes shown in .

[0143] Here, the calculation process in step S112 is supplemented.

[0144] The following [Expression 2] represents the relationship between the phase difference θ(h, t, u, v) at the pixel position (u, v) in the h-th measurement and the distance L(h, u, v) to the distance measurement target point (distance measurement point) projected at the pixel position (u, v). Here, t is 1 to T.

[0145] [Expression 2]

[0146]

[0147] where φ(h，t，u，v) =θ (h，t，u，v) +a (t) +b (t) u+C (t) v

[0148] [Expression 2]

[0149] As is clear from the analogy of [Expression 1], [Expression 2] holds true. In [Expression 2], the distance L(h, u, v) does not depend on t. Of course, even when measuring while changing the frequency f(t), the distance to the target object Ob does not change, so L(h, u, v) does not depend on t. Furthermore, since the distance to the target object Ob is unknown, L(h, u, v) is an unknown number.

[0150] Furthermore, in [Expression 2], by reading the information stored as parameter information 9a, the parameters a(t), b(t), and c(t) of the signal propagation delay at each frequency f(t) can be known. Here, t is 1 to T.

[0151] In this example, although the parameters of An and Bn are obtained through calibration, it is assumed that the values ​​at the time of factory shipment are continuously used for the parameters a(t), b(t), and c(t) of the signal propagation delay.

[0152] Therefore, it is only necessary to use the data other than (h, u, v) discarded in step S108 to obtain the parameters A1(t) to An(t) and B1(t) to Bn(t) that satisfy [Expression 2]. In fact, it is obtained by the least squares method. Specifically, it is only necessary to obtain A1(t) to An(t) and B1(t) to Bn(t) and L(h, u, v) that minimize [Expression 3].

[0153] [Expression 3]

[0154]

[0155] where φ (h，t，u，v) =θ (h，t，u，v) +a (t) +b (t) u+C (t) v

[0156] [Expression 3]

[0157] Here, the effectiveness of the present method will be supplemented.

[0158] [Expression 3] holds true for each of (h, t, u, v) in h = 1 to H, t = 1 to T, u = 1 to U, and v = 1 to V. That is, when the process enters step S112, H is obtained, that is, when the equation. On the other hand, the unknown parameters are the sum of An(t) (n = 1 to N and t = 1 to T), Bn(t) (n = 1 to N and t = 1 to T), and L(h, u, v) (h = 1 to H, u = 1 to U, and v = 1 to V) (2×N×T) + (H×U×V). Therefore, if (2×N×T) + (H×U×V) ≤ H×U×V×T, the number of equations is greater than the number of unknowns, and a solution can be performed. In fact, by increasing T, that is, by increasing the number of light emission frequencies of the light emitting unit 2, (2×N×T) + (H×U×V) ≤ H×U×V×T can be satisfied. Alternatively, by increasing H, (2×N×T)+(H×U×V)≤H×U×V×T can be satisfied, that is, the phase differences of various scenes can be measured.

[0159] That is, this embodiment utilizes the fact that (2×N×T)+(H×U×V)≤H×T×U×V can be satisfied when T is 2 or greater. In other words, the feature of this embodiment is "measuring the phase difference using multiple light emission frequencies (at least two different light emission frequencies) of the same object." Therefore, even if the distance to the object is unknown, the unknown parameters An(t) (n=1 to N and t=1 to T), Bn(t) (n=1 to N and t=1 to T), and L(h, u, v) (h=1 to H, u=1 to U, and v=1 to V) can be obtained. That is, the cyclic error (An(t) (n=1 to N and t=1 to T), Bn(t) (n=1 to N and t=1 to T)) can be obtained.

[0160] It should be noted that Figure 3 In step S108, when the process of setting h=h-1 when discarding data is performed, if it is determined that T and H make H×U×V×T sufficiently larger than (2×N×T)+(H×U×V) (the number of measurement data has a margin), the process of setting h=h-1 can be omitted.

[0161] Figure 4 3 is a flowchart showing the 2π uncertainty elimination process of step S111 .

[0162] As reference Figure 2 As described, the phase difference p(h, t, u, v) measured for each pixel of the sensor unit 3 has an uncertainty of 2π. That is, for each (h, t, u, v), it is unclear which of the following [Expression 4] is the true phase difference θ(h, t, u, v).

[0163] [Expression 4]

[0164] θ (h，t，u，v) =p (h，t，u，v) +2s (h，t，u，v) π

[0165] [Expression 4]

[0166] It should be noted that in [Expression 4], s(h, t, u, v) is an integer of 0 or greater.

[0167] Here, as the distance to the target object Ob increases, the amount of light reflected from the light emitting unit 2 by the target object Ob and reaching the sensor unit 3 also decreases. That is, the light reception signal has a small amplitude. In addition, since the data with a small amplitude is discarded in step S108, the distance to the target object Ob corresponding to the (h, t, u, v) as the target in step S111 is not long. Therefore, it can be said that the distance to the target object Ob corresponding to the (h, t, u, v) as the target in step S111 satisfies [Expression 5].

[0168] [Expression 5]

[0169]

[0170] It should be noted that f(1) in [Expression 5] is the lowest frequency among the frequencies f(t) from t=1 to T as described above.

[0171] Therefore, for t=1, in [Expression 4], the true phase difference θ(h, t, u, v) is s(h, t, u, v)=0 and can be determined from the phase difference p(h, t, u, v) measured for each pixel of the sensor unit 3 by the following [Expression 6].

[0172] [Expression 6]

[0173] θ (h，1，u，v) =p (h，1，u，v)

[0174] [Expression 6]

[0175] Furthermore, the illumination light Ls emitted from the light emitting unit 2 is not a perfect sine wave but has a waveform substantially similar to a sine wave, and therefore the amount of cyclic error is small. From this point of view, the following [Expression 7] is established.

[0176] [Expression 7]

[0177]

[0178] In [Expression 7], when t = 1, it is determined that s(h, t, u, v) = 0. Therefore, the following [Expression 8] is established.

[0179] [Expression 8]

[0180]

[0181] By modifying [Expression 8], the following [Expression 9] is obtained.

[0182] [Expression 9]

[0183]

[0184] For t=2 to T, s(h, t, u, v) can be determined from [Expression 9]. That is, it is only necessary to set the integer closest to the following [Expression 10] as s(h, t, u, v).

[0185] [Expression 10]

[0186]

[0187] When s(h, t, u, v) is determined for t=2 to T, the true phase difference θ(h, t, u, v) can also be determined by the above-mentioned [Expression 4].

[0188] Based on the above description Figure 4 processing.

[0189] First, in step S1111, the calibration calculation unit 8a sets θ(h, 1, u, v) at frequency f(1) to p(h, 1, u, v). That is, θ(h, 1, u, v) = p(h, 1, u, v). As described above, the frequency f(1) at t = 1 is lower than the other frequencies (f(2) to f(T)).

[0190] In step S1112 following step S1111 , the calibration calculation unit 8 a obtains an integer closest to the value of [Expression 10] for each t from t=2 to T, and sets the obtained integer as s(h, t, u, v).

[0191] Furthermore, in step S1113 following step S1112 , the calibration calculation unit 8 a calculates [Expression 4] for each t from t=2 to T, and obtains the true phase difference θ(h, t, u, v).

[0192] In response to the execution of the process of step S1113 , the calibration calculation unit 8 a ends the 2π uncertainty elimination process of step S111 .

[0193] Here, the above-mentioned uncertainty elimination process can be restated as follows.

[0194] That is, when light transmission is performed at the lowest light transmission frequency (frequency f(1)) among the light transmission frequencies used for calibration calculation processing, among the phase differences detected in the received light signal, the phase difference detected from the light receiving signal having an amplitude equal to or greater than a predetermined value is determined as the phase difference corresponding to the lowest light transmission frequency, and based on the determined phase difference corresponding to the lowest light transmission frequency, a process of eliminating 2π uncertainty regarding the phase differences corresponding to light transmission frequencies other than the lowest light transmission frequency is performed.

[0195] <2. Second embodiment>

[0196] Next, a second embodiment will be described.

[0197] In the second embodiment, calibration is performed for obtaining correction parameters in the background.

[0198] Note that in the second embodiment, the hardware configuration of the distance measuring device 1 is the same as that of the first embodiment, and therefore illustration thereof is omitted.

[0199] Figure 5 is a flowchart of the processing executed by the control unit 8 in the second embodiment.

[0200] For example, in response to satisfying a predetermined trigger condition determined in advance (for example, turning on the power of the distance measuring device 1 or activating an application for distance measurement), the distance measuring device 1 is started. Figure 5 The processing shown in .

[0201] In this case, in step S201, the control unit 8 determines whether a predetermined time (e.g., one year, etc.) has passed since the previous calibration. When the predetermined time has passed, there is a possibility that a long-term change has occurred. Therefore, in the event that it is determined in step S201 that the predetermined time has passed, the control unit 8 performs Figure 6 The processing of the calibration calculation unit 8a shown in FIG.

[0202] On the other hand, if the predetermined time has not passed, it is considered that no long-term change has occurred and no execution is performed. Figure 6 The processing shown in .

[0203] If the predetermined time has not elapsed, the control unit 8 proceeds to step S202 and waits for a distance measurement instruction from the user via the operation unit 11, for example, as a distance measurement instruction. If a distance measurement instruction is received, the control unit 8 proceeds to step S203 and performs distance measurement processing. Specifically, the light emitting unit 2 performs a light emitting operation for the irradiation light Ls and the sensor unit 3 performs a light receiving operation for the reflected light Lr, causing the phase difference detection unit 5 to detect a phase difference and causing the calculation unit 6 to calculate a distance.

[0204] In response to the execution of the distance measurement process in step S203 , the control unit 8 returns to step S202 .

[0205] In the second embodiment, by Figure 6 The processing shown performs calibration between distance measurement processes performed in accordance with a distance measurement instruction from the user.

[0206] Figure 6 The processing shown in Figure 3 The difference between the processing in is that the processing in step S204 and step S205 is inserted between step S108 and step S109.

[0207] In this case, in response to the execution of the discarding process in step S108, the control unit 8 (calibration calculation unit 8a) proceeds to step S204 and determines whether a distance measurement instruction is given. In the case where there is no distance measurement instruction, the control unit 8 proceeds to step S109. That is, if there is no distance measurement instruction, the process proceeds to the same step as Figure 3 The same processing as in (the process enters step S109 after the processing of step S108).

[0208] In the case where a distance measurement instruction has been given, the control unit 8 proceeds to step S205 , executes distance measurement processing (similar processing to step S203 described above), and proceeds to step S109 .

[0209] Figure 6 The processing flow in Figure 3 The processing flow in is basically the same, but the difference is that in Figure 3 When a distance measurement instruction is given between step S108 and step S109 in , the calibration process is temporarily interrupted and the distance measurement is performed (step S205).

[0210] In this case, the control unit 8 advances the processing to step S112 in response to the execution of the processing. Figure 5 Step S202 in .

[0211] As described above, in the second embodiment, calibration for obtaining correction parameters can be performed in the background while the user is using the distance measurement device 1 .

[0212] <3. Third embodiment>

[0213] In the third embodiment, calibration is performed on the condition that the distance measurement points have a specific positional relationship with each other.

[0214] Figure 7 1A is a block diagram for describing an internal configuration example of a distance measurement device 1A as a third embodiment.

[0215] The difference from the distance measuring device 1 is that a control unit 8A is provided in place of the control unit 8. The hardware configuration of the control unit 8A is similar to that of the control unit 8, but the difference of the control unit 8A is that the calibration calculation processing is performed using a method different from that of the first embodiment. Here, the function of performing the calibration calculation processing using the method of the third embodiment described later is referred to as the calibration calculation unit 8aA.

[0216] In the third embodiment, Figure 8 As shown, calibration is performed by tilting the image capture (measuring the phase difference) of a plate 20 at an unknown distance. The distance to the plate 20 may be unknown, and therefore no precise means are required.

[0217] Figure 8 A state in which a portion of the flat plate 20 is projected onto the distance measuring device 1A side is schematically shown.

[0218] Here, also in the third embodiment, the number of pixels of the sensor unit 3 is represented by U pixels, and each pixel position is represented by (u, v) (u=1 to U and v=1 to V).

[0219] In this example, the area of ​​(u, v) (u=U0 to U0+U1, v=V0 to V0+V1) is referred to as a planar imaging area Ar. For example, U0=U / 4, V0=V / 3, U1=U / 2, and V1=V / 3.

[0220] These positional relationships are Figure 9 Shown in.

[0221] At the time of calibration, the user performs image capturing so that the same plane of the tablet 20 appears in the planar imaging area Ar of the sensor unit 3 .

[0222] In this example, the control unit 8A causes the display unit 10 to display a guide image so that guidance for the user to perform image capturing (ie, guidance of imaging composition) is performed so that the same plane of the tablet 20 appears in the planar imaging area Ar in this manner.

[0223] Figure 10 is a diagram for describing an example of a guide display at the time of calibration including the display of such a guide image.

[0224] First, display Figure 10 The calibration inquiry screen shown in A. On this calibration inquiry screen, a “Yes” button B1 and a “No” button B2 and an inquiry message such as “Do you want to calibrate?” as to whether to execute calibration are displayed.

[0225] In the case where an instruction to perform calibration is given, the user operates the “Yes” button B1 .

[0226] When the "Yes" button B1 is pressed, the Figure 10 The frame screen shown in B. On the frame screen, a frame W indicating the size of the above-mentioned planar imaging area Ar is displayed, a message prompting the tablet 20 to be included in the frame W, such as "Please include the same plane of the tablet in the frame", and an "image capture" button B3 for giving an instruction to start measuring the phase difference for calibration are displayed.

[0227] In this example, as in the case of the first embodiment, H measurements are performed while changing the distance in calibration. Figure 10 In the frame screen shown in B, when the “image capture” button B3 is operated and the first measurement is performed, the image is displayed on the display unit 10. Figure 10 The frame screen shown in C.

[0228] and Figure 10 The frame screen in B is different in that a message prompting image capture at different distances, such as “Please capture the image at a different position”, is displayed.

[0229] When H measurements are performed and the calibration calculation process is completed, the Figure 10 Calibration completion screen shown in D. As shown in the figure, on the calibration completion screen, a message providing notification that the calibration calculation process has been completed, such as, “Calibration has been completed”, is displayed.

[0230] Here, in Figure 10 B or Figure 10 An image (eg, a distance image) obtained by the light receiving operation of the sensor unit 3 is displayed in real time on the frame screen in C. Thus, the user can easily adjust the composition to an appropriate composition while viewing the screen of the display unit 10.

[0231] Note that the object used at the time of calibration is not limited to the tablet 20. For example, it may be a wall of the user's house, an outer wall of a building, or the like.

[0232] Figure 11 is a flowchart showing the flow of processing when calibration is performed as the third embodiment.

[0233] For example, in response to a predetermined trigger condition being satisfied (eg, turning on the power of the distance measuring device 1A or activating an application for distance measurement), the distance measuring device 1A is started. Figure 11 The processing shown in .

[0234] First, in step S301, the control unit 8A causes the display unit 10 to display the following Figure 10 The process of the calibration inquiry screen shown in A is a display process of the calibration inquiry screen.

[0235] In step S302 following step S301, the control unit 8A stands by until the above-mentioned "Yes" button B1 is operated, and in the case where the "Yes" button B1 is operated, the process proceeds to step S303 to perform Figure 10 The display process of the frame screen shown in B.

[0236] Note that, for example, in the case where the “NO” button B2 is operated on the calibration inquiry screen, it is only necessary to perform processing for transitioning to a predetermined screen (for example, a distance measurement screen).

[0237] In step S304 following step S303 , the control unit 8A stands by until the “image capture” button B3 on the frame screen is operated, and when the “image capture” button B3 is operated, the control unit 8A executes the calibration process of step S305 and proceeds to step S306 .

[0238] It should be noted that the calibration process in step S305 is performed under the condition that the distance measurement points have a specific positional relationship with each other, and the details will be described later.

[0239] In step S306, the control unit 8A executes Figure 10 The calibration completion screen shown in D is displayed and the process is terminated. Figure 11 A series of processing shown.

[0240] Figure 12 This is a flowchart of the calibration process in step S305.

[0241] As shown in the figure, Figure 12 The calibration process shown in the above reference Figure 3 The difference in the described calibration processing is that the standby processing (time k) in step S109 is omitted, the processing in step S310 (image capture button standby processing) is performed according to the execution of the processing in step S108, and the processing in step S311 is performed instead of the processing in step S112.

[0242] First, regarding the determination process in step S102, in this case, H is also set to, for example, H = 40. In the third embodiment, the phase difference is measured only H times in different compositions (i.e., the user moves the distance measuring device 1A). That is, in the third embodiment, it is assumed that each time the value of h increases, the plane at a different distance is measured.

[0243] Furthermore, in this example, as the calibration calculation process, a method using multiple light emission frequencies, as in the first embodiment, is used, while also employing the condition that the distance measurement points are in a specific positional relationship with each other. Therefore, in the third embodiment as well, phase differences are measured for multiple t values, where t = 1 to T.

[0244] exist Figure 12 In the processing of , in response to the execution of the discarding processing of step S108, the control unit 8A proceeds to step S310 and waits until the “image capture” button B3 is operated.

[0245] Note that, although omitted from the illustration, in the third embodiment, Figure 10 After pressing the "IMAGE CAPTURE" button B3 on the frame screen shown in FIG. 1 and before executing the discarding process in step S108 for the first time, the control unit 8A updates the frame screen to Figure 10 Therefore, the "image capture" button B3 for waiting for the operation in step S310 is Figure 10 “Image capture” button B3 on the frame screen shown in C.

[0246] In the event that determination is made in step S310 that the “image capture” button B3 has been operated, the control unit 8A advances the processing to step S110 .

[0247] Furthermore, in the third embodiment, the target for which the phase difference is detected in the process of step S106 is within the range of u = U0 to U0 + U1 and v = V0 to V0 + V1 in each pixel position (u, v) of the sensor unit 3. Therefore, the phase difference detected for each distance measurement point on the same plane can be used for the calculation process of the correction parameter.

[0248] Similar to the above Figure 3 The processing of step S112, step S311 shown in FIG. 3 is basically a processing of obtaining parameters (parameters A1(t) to An(t) and B1(t) to Bn(t)) of the cyclic error satisfying [Expression 3].

[0249] In response to the execution of the process in step S311 , the control unit 8A terminates the calibration process in step S305 .

[0250] Here, regarding the processing in step S311, in the third embodiment, when [Expression 3] is solved, certain conditions exist.

[0251] Hereinafter, the calculation in step S311 will be described in detail.

[0252] First, the orientation of the image captured by the pixel position (u, v) is given by (d x (u, v), d y (u, v), d z (u, v)) is represented. For example, assuming that lens 4 has no distortion and the focal length is F L , the direction in which the pixel position (u, v) is captured by the image is expressed by the following [Expression 11].

[0253] [Expression 11]

[0254]

[0255] The pixel position (u, v) captures the orientation of the image (d x (u, v), d y (u, v), d z (u, v)) is determined by the characteristics of the lens 4. Then, for example, since the characteristics are determined when the lens 4 is designed, the characteristics can be known.

[0256] Note that assuming the three-dimensional vector (d x (u, v), d y (u, v), d z (u, v)) is normalized. That is, it is assumed that the following [Expression 12] is satisfied.

[0257] [Expression 12]

[0258]

[0259] Assuming that the distance to the point on the flat panel 20 projected at the pixel position (u, v) at the time of the h-th image capture of the flat panel 20 is represented by L(h, u, v), the position of the point on the flat panel 20 projected at the pixel position (u, v) in the three-dimensional space is represented by [Expression 13].

[0260] [Expression 13]

[0261]

[0262] Consider the position of tablet 20 in three-dimensional space at time h. In this example, the positions of objects in three-dimensional space projected at all pixel positions (u, v) (u = U0 to U0+U1, v = V0 to V0+V1) are on a single plane. That is, on the plane passing through the positions of objects in three-dimensional space projected at the three pixel positions (U0, V0), (U0+1, V0), and (U0, V0+1), there are also positions of objects in three-dimensional space projected at pixel positions at other positions (u, v). Therefore, the following [Expression 14] is satisfied.

[0263] [Expression 14]

[0264]

[0265] Note that the notation T in [Expression 14] represents a transposed matrix.

[0266] In summary, the known pixel position (u, v) captures the direction (d x (u, v), d y (u, v), d z (u, v)). Then, since the same plane is imaged in the plane imaging area Ar in the h-th image capturing (measurement of the phase difference), [Expression 14] is satisfied for pixels where u=U0 to U0+U1 and v=V0 to V0+V1. Note that L(h, u, v) in [Expression 14] is the distance from the flat panel 20 projected at the pixel position (u, v) when the flat panel 20 is imaged for the h-th time.

[0267] Now, [Expression 2] represents the relationship between the phase difference θ(h, t, u, v) at the pixel position (u, v) in the h-th measurement and the distance L(h, u, v) to the distance measurement point projected at the pixel position (u, v). Here, t is 1 to T.

[0268] As described above, it is clear from the similarity of [Expression 1] that [Expression 2] holds.

[0269] Note that since the distance to the target object Ob is unknown, L(h, u, v) is an unknown number. However, L(h, u, v) satisfies [Expression 14] as described above.

[0270] Therefore, under the condition of satisfying [Expression 14], it is only necessary to obtain the parameters A1(t) to An(t) and B1(t) to Bn(t) that satisfy [Expression 2]. In fact, in this case as well, it is determined by the least squares method, and therefore, under the condition of satisfying [Expression 14], it is only necessary to obtain A1(t) to An(t) and B1(t) to Bn(t) and L(h, u, v) that minimize the above [Expression 3].

[0271] That is, the calculation in step S311 is to obtain A1(t) to An(t) and B1(t) to Bn(t) and L(h, u, v) that minimize [Expression 3] under the condition that [Expression 14] is satisfied for each (u, v) (where u = U0 to U0 + U1, v = V0 to V0 + V1). Then, the obtained parameters A1(t) to An(t) and B1(t) to Bn(t) are used as parameters of the cyclic error.

[0272] Here, the calibration method that supplements the third embodiment (the method using the condition that the distance measurement points are in a specific positional relationship) is effective. In step S311, "a solution to the equation that satisfies [Expression 2] and [Expression 14] is obtained."

[0273] [Expression 2] holds true for each (h, t, u, v) of h=1 to H, t=1 to T, u=U0 to U0+U1, and v=V0 to V0+V1. That is, when the process enters step S311, H is obtained, and , that is, when the process Eq.

[0274] Furthermore, [Expression 14] holds for each (h, u, v) where h = 1 to H, u = U0 to U0+U1, and v = V0 to V0+V1. However, the sets (u, v) = (U0, V0), (u, v) = (U0+1, V0), and (u, v) = (U0, V0+1) are excluded. That is, the equation H × (U1 × V1-3) ​​is obtained.

[0275] Therefore, when proceeding to step S311 , the equation of (H×T×U1×V1)+(H×(U1×V1−3)) is obtained.

[0276] On the other hand, the unknown parameters are the sum of An(t) (n=1 to N and t=1 to T), Bn(t) (n=1 to N and t=1 to T), and L(h, u, v) (h=1 to H, u=U0 to U0+U1, v=V0 to V0+V1), (2×N×T)+(H×U1×V1). Therefore, if (2×N×T)+(H×U1×V1)≤(H×T×U1×V1)+(H×(U1×V1–3)), the number of equations is greater than the number of unknowns, and they can be solved. In fact, if at least one of U1, V1, or H is sufficiently large, (2×N×T)+(H×U1×V1)≤(H×T×U1×V1)+(H×(U1×V1–3)) can be satisfied.

[0277] Note that the above inequality can be satisfied even if T = 1. That is, in the first embodiment, T needs to be a natural number greater than 2, but in the third embodiment, T only needs to be a natural number greater than 1.

[0278] It should be noted that, regarding Figure 12 The 2π uncertainty elimination process in step S111 is the same as that in Figure 4 The processing described in is similar, so redundant description is avoided.

[0279] <4. Modifications>

[0280] It should be noted that the embodiment is not limited to the specific examples described above, and various modifications can be adopted.

[0281] For example, although an example has been described above in which the distance measuring device according to the present technology is applied to a portable information processing device such as a smartphone, the distance measuring device according to the present technology is not limited to being applied to portable information processing devices and can be widely and appropriately applied to various electronic devices.

[0282] In addition, the Figure 3 The processing described in the third embodiment Figure 12 In the process of , when the (h+1)th measurement is performed from the hth measurement, it is desired to change the positional relationship with the target object Ob. Therefore, for example, in Figure 3 In the process of determining whether distance measurement device 1 is moving based on the detection signal of the acceleration sensor or angular velocity sensor built into distance measurement device 1, a process may be set between steps S109 and S110. In this case, if distance measurement device 1 is moving, the process proceeds to step S110; if not, the determination process is repeated. Therefore, the (h+1)th measurement can be reliably performed on an object at a distance different from the distance measured in the hth measurement.

[0283] In addition, for Figure 12 For example, it is conceivable to similarly provide a process of determining whether the distance measuring device 1A has moved between step S310 and step S110, and if the distance measuring device 1 is moving, proceed to step S110, and if not, perform the determination process again.

[0284] <5. Overview of Examples>

[0285] As described above, the first distance measuring device (same as 1) of the present embodiment includes: a light emitting unit (same as 2) that emits light; a receiving light sensor (sensor unit 3) that receives light emitted from the light emitting unit and reflected by the target object; and a calibration calculation unit (same as 8a) that performs a calibration calculation process as a correction parameter for obtaining distance information calculated by an indirect ToF method based on a light receiving signal of the light receiving sensor, and performs calculation processing using a light receiving signal of the light receiving sensor when the light emitting unit emits light at a first light transmitting frequency, and a light receiving signal of the light receiving sensor when the light emitting unit emits light at a second light transmitting frequency different from the first light transmitting frequency.

[0286] By using multiple light emission frequencies, correction parameters can be obtained even if the distance to the target object is uncertain.

[0287] Therefore, the prerequisites for establishing calibration can be alleviated, and calibration can be performed even in the actual use environment of the device.

[0288] Since calibration can be performed even in an actual use environment, changes in correction parameters due to secular changes can be absorbed, and degradation of distance measurement accuracy over time can be suppressed.

[0289] Furthermore, in the first distance measuring device as the embodiment, the calibration calculation unit performs calculation processing based on a phase difference between light transmission and light reception, the phase difference being detected by the light reception signal, and obtains the correction parameter.

[0290] Therefore, it is possible to obtain appropriate correction parameters corresponding to the case where distance measurement is performed by the indirect ToF method which is a phase difference method.

[0291] Furthermore, in the first distance measurement device as the embodiment, the calibration calculation unit performs uncertainty elimination processing of eliminating uncertainty in units of 2π with respect to the phase difference (see step S111 ).

[0292] Therefore, the calculation process of the correction parameter can be performed using the phase difference from which the uncertainty in units of 2π has been eliminated.

[0293] Therefore, the accuracy of the correction parameter can be improved, and the distance measurement accuracy can be improved.

[0294] In addition, in the first distance measuring device as an embodiment, the calibration calculation unit determines, among phase differences detected from the light receiving signals, a phase difference detected from the light receiving signals having an amplitude equal to or greater than a predetermined value, as the phase difference corresponding to the lowest light transmission frequency, when light transmission is performed at the lowest light transmission frequency among the light transmission frequencies of the light transmitting units used for calibration calculation processing, and performs uncertainty elimination processing related to phase differences corresponding to light transmission frequencies other than the lowest light transmission frequency, based on the determined phase difference corresponding to the lowest light transmission frequency.

[0295] With respect to the phase difference corresponding to the lowest light emission frequency, as described above, by selecting the phase difference detected from the light receiving signal having an amplitude equal to or greater than a predetermined value, uncertainty in units of 2π can be eliminated, and with respect to the phase difference corresponding to another one of the light emission frequencies other than the lowest light emission frequency, a true phase difference can be specified based on the phase difference corresponding to the lowest light emission frequency in which uncertainty is eliminated in this manner (i.e., uncertainty in units of 2π can be eliminated).

[0296] Therefore, the calculation process of the correction parameter can be performed based on the phase difference from which the uncertainty in units of 2π has been eliminated, and by improving the accuracy of the correction parameter, the distance measurement accuracy can be improved.

[0297] Furthermore, in the first distance measurement device as the embodiment, the calibration calculation unit executes the calibration calculation process based on the elapsed time from the previous execution (see step S201 ).

[0298] Therefore, even in the event that the correction parameter deviates from the true value over time, the correction parameter can be recalibrated.

[0299] Therefore, it is possible to prevent the distance measurement accuracy from being deteriorated over time as the correction parameter changes over time.

[0300] Furthermore, in the first distance measuring device as the embodiment, in the case where a distance measurement instruction is given during execution of the calibration calculation process, the calibration calculation unit interrupts the calibration calculation process and performs processing for distance measurement (see FIG. Figure 6 ).

[0301] Therefore, even in the case where the calibration calculation process is executed in the background, the calibration calculation process is interrupted when a distance measurement instruction is given, and the distance measurement operation is performed according to the instruction.

[0302] Therefore, usability can be improved.

[0303] In addition, a first calibration method as an embodiment is a calibration method in a distance measuring device, which includes: a light emitting unit that emits light; and a light receiving sensor that receives light emitted from the light emitting unit and reflected by a target object, and performs distance measurement by an indirect ToF method based on a light receiving signal of the light receiving sensor, the calibration method including: calibration calculation processing as a correction parameter for obtaining distance information calculated by the indirect ToF method, using a light receiving signal of the light receiving sensor when the light emitting unit emits light at a first light transmitting frequency, and a light receiving signal of the light receiving sensor when the light emitting unit emits light at a second light transmitting frequency different from the first light transmitting frequency, to perform calculation processing.

[0304] Furthermore, by this first calibration method, operations and effects similar to those of the above-described first distance measuring device can be obtained.

[0305] The second distance measuring device (same as 1A) as an embodiment includes: a light emitting unit (same as 2) that emits light; a light receiving sensor (sensor unit 3) that receives light emitted from the light emitting unit and reflected by a target object of multiple pixels; and a calibration calculation unit (same as 8aA) that performs calibration calculation processing as a correction parameter for obtaining distance information calculated by an indirect ToF method based on a light receiving signal of the light receiving sensor, and performs calibration calculation processing using the condition that corresponding distance measurement points projected onto multiple pixels are in a specific positional relationship with each other.

[0306] As described above, by using the condition that the distance measurement points have a specific positional relationship with each other, correction parameters can be obtained even if the distance to the target object is uncertain.

[0307] Therefore, the prerequisites for establishing calibration can be alleviated, and calibration can be performed even in the actual use environment of the device.

[0308] Since calibration can be performed even in an actual use environment, changes in correction parameters due to secular changes can be absorbed, and degradation of distance measurement accuracy over time can be suppressed.

[0309] Furthermore, in the second distance measurement device as the embodiment, the calibration calculation unit performs calculation processing using a condition that the distance measurement points are located on an object having a known shape with each other as the calibration calculation processing.

[0310] If the distance measurement points are located on an object having a known shape relative to each other, the positional relationship between the distance measurement points can be defined as a mathematical expression based on the known shape.

[0311] Therefore, the prerequisites for establishing calibration can be alleviated, and calibration can be performed even in the actual use environment of the device.

[0312] Furthermore, since calibration can be performed even in an actual use environment, changes in correction parameters due to secular changes can be absorbed, and degradation of distance measurement accuracy over time can be suppressed.

[0313] Furthermore, in the second distance measuring device as an embodiment, the calibration calculation unit performs calculation processing using, as calibration calculation processing, a light reception signal of the light reception sensor when the light transmission unit transmits light at a first light transmission frequency and a light reception signal of the light reception sensor when the light transmission unit transmits light at a second light transmission frequency different from the first light transmission frequency (see Figure 12 ).

[0314] That is, as the calibration calculation process, the calculation process using a plurality of light emission frequencies is performed under the condition that the respective distance measurement points are in a specific positional relationship with each other, and thus the number of equations of unknowns can be increased.

[0315] Therefore, the correction parameter can be obtained more stably, and the distance measurement accuracy can be improved.

[0316] Furthermore, in the second distance measuring device as the embodiment, the calibration calculation unit performs calculation processing based on a phase difference between light transmission and light reception, the phase difference being detected based on a light reception signal, and obtains the correction parameter.

[0317] Therefore, it is possible to obtain appropriate correction parameters corresponding to the case where distance measurement is performed by the indirect ToF method which is a phase difference method.

[0318] Furthermore, in the second distance measurement device as the embodiment, the calibration calculation unit performs uncertainty elimination processing of eliminating uncertainty in units of 2π with respect to the phase difference.

[0319] Therefore, the calculation process of the correction parameter can be performed using the phase difference from which the uncertainty in units of 2π has been eliminated.

[0320] Therefore, the accuracy of the correction parameter can be improved, and the distance measurement accuracy can be improved.

[0321] In addition, in the second distance measuring device as an embodiment, the calibration calculation unit determines, among phase differences detected from the light reception signals, a phase difference detected from the light reception signals having an amplitude equal to or greater than a predetermined value, as the phase difference corresponding to the lowest light transmission frequency, when light transmission is performed at the lowest light transmission frequency among the light transmission frequencies of the light transmission units used for calibration calculation processing, and performs uncertainty elimination processing related to the phase difference corresponding to another light transmission frequency other than the lowest light transmission frequency, based on the determined phase difference corresponding to the lowest light transmission frequency.

[0322] With respect to the phase difference corresponding to the lowest light emission frequency, as described above, by selecting the phase difference detected from the light receiving signal having an amplitude equal to or greater than a predetermined value, uncertainty in units of 2π can be eliminated, and with respect to the phase difference corresponding to another one of the light emission frequencies other than the lowest light emission frequency, a true phase difference can be specified based on the phase difference corresponding to the lowest light emission frequency in which uncertainty is eliminated in this manner (i.e., uncertainty in units of 2π can be eliminated).

[0323] Therefore, the calculation process of the correction parameter can be performed based on the phase difference from which the uncertainty in units of 2π has been eliminated, and by improving the accuracy of the correction parameter, the distance measurement accuracy can be improved.

[0324] Furthermore, the second distance measuring device as an embodiment includes a guide display processing unit (control unit 8A, see Figure 10 and Figure 11 ), the guide display processing unit performs display processing of a guide image that guides a composition that satisfies a condition that distance measurement points are in a specific positional relationship with each other.

[0325] Therefore, it is possible to increase the possibility of calibrating the correction parameters under the condition that the distance measurement points are in a specific positional relationship with each other.

[0326] Therefore, the accuracy of the correction parameter can be improved, and the distance measurement accuracy can be improved.

[0327] In addition, a second calibration method as an embodiment is a calibration method in a distance measuring device, which uses a light emitting unit that emits light and a light receiving sensor that receives light emitted from the light emitting unit and reflected by a target object by a plurality of pixels, and performs distance measurement by an indirect ToF method based on a light receiving signal of the light receiving sensor. The calibration method includes: as a calibration calculation processing for obtaining a correction parameter for distance information calculated by the indirect ToF method, the calculation processing is performed using a condition that corresponding distance measurement points projected onto a plurality of pixels are in a specific positional relationship with each other.

[0328] Also, by this second calibration method, operations and effects similar to those of the above-described second distance measuring device can be obtained.

[0329] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may be provided.

[0330] <6. This technology>

[0331] Note that the present technology can adopt the following configurations. (1)

[0333] A distance measuring device, comprising:

[0334] a light emitting unit, emitting light;

[0335] a light receiving sensor that receives light emitted from the light emitting unit and reflected by the target object; and

[0336] A calibration calculation unit performs a calibration calculation process as a correction parameter for obtaining distance information calculated by an indirect ToF method based on a light reception signal of the light reception sensor, using the light reception signal of the light reception sensor when the light transmission unit transmits light at a first light transmission frequency and the light reception signal of the light reception sensor when the light transmission unit transmits light at a second light transmission frequency different from the first light transmission frequency. (2)

[0338] The distance measuring device according to (1), wherein

[0339] Calibration calculation unit

[0340] A calculation process is performed based on the phase difference between light emission and light reception, which is detected based on the light reception signal, and a correction parameter is obtained. (3)

[0342] The distance measuring device according to (2), wherein

[0343] Calibration calculation unit

[0344] Uncertainty elimination processing is performed on the phase difference in units of 2π to eliminate uncertainty. (4)

[0346] The distance measuring device according to (3), wherein

[0347] Calibration calculation unit

[0348] When light emission is performed at the lowest light emission frequency among the light emission frequencies of the light emission unit used for calibration calculation processing, among phase differences detected from the light reception signal, the phase difference detected from the light reception signal having an amplitude equal to or greater than a predetermined value is determined as the phase difference corresponding to the lowest light emission frequency, and based on the determined phase difference corresponding to the lowest light emission frequency, uncertainty elimination processing is performed with respect to phase differences corresponding to light emission frequencies other than the lowest light emission frequency. (5)

[0350] The distance measuring device according to any one of (1) to (4), wherein

[0351] Calibration calculation unit

[0352] The calibration calculation process is executed based on the elapsed time from the previous execution. (6)

[0354] The distance measuring device according to any one of (1) to (5), wherein

[0355] In the case where a distance measurement instruction is given during execution of the calibration calculation process, the calibration calculation unit interrupts the calibration calculation process and performs processing for distance measurement. (7)

[0357] A calibration method for a distance measuring device, the distance measuring device comprising: a light emitting unit that emits light; and a light receiving sensor that receives light emitted from the light emitting unit and reflected by a target object, and performing distance measurement using an indirect ToF method based on a light reception signal of the light receiving sensor, the calibration method comprising:

[0358] As a calibration calculation process for obtaining correction parameters for distance information calculated by the indirect ToF method, calculation processing is performed using a light receiving signal of the light receiving sensor when the light emitting unit transmits light at a first light transmitting frequency, and a light receiving signal of the light receiving sensor when the light emitting unit transmits light at a second light transmitting frequency different from the first light transmitting frequency. (8)

[0360] A distance measuring device, comprising:

[0361] a light emitting unit, emitting light;

[0362] a light receiving sensor that receives light emitted from the light emitting unit and reflected by the target object, including a plurality of pixels; and

[0363] The calibration calculation unit performs calculation processing as a calibration calculation processing for obtaining correction parameters for distance information calculated by the indirect ToF method based on the light reception signal of the light reception sensor, using the condition that corresponding distance measurement points projected onto a plurality of pixels are in a specific positional relationship with each other. (9)

[0365] The distance measuring device according to (8), wherein

[0366] Calibration calculation unit

[0367] The calculation process is performed as the calibration calculation process using the condition that the distance measurement points are located on an object having a known shape from each other. (10)

[0369] The distance measuring device according to (8) or (9), wherein:

[0370] Calibration calculation unit

[0371] As calibration calculation processing, calculation processing is performed using a light reception signal of the light reception sensor when the light emitting unit transmits light at a first light transmission frequency, and a light reception signal of the light reception sensor when the light emitting unit transmits light at a second light transmission frequency different from the first light transmission frequency. (11)

[0373] The distance measuring device according to any one of (8) to (10), wherein

[0374] Calibration calculation unit

[0375] A calculation process is performed based on a phase difference between light transmission and light reception, the phase difference being detected based on the light reception signal, and a correction parameter is obtained. (12)

[0377] The distance measuring device according to (11), wherein

[0378] Calibration calculation unit

[0379] Uncertainty elimination processing is performed on the phase difference in units of 2π to eliminate uncertainty. (13)

[0381] The distance measuring device according to (12), wherein

[0382] Calibration calculation unit

[0383] When light transmission is performed at the lowest light transmission frequency among the light transmission frequencies of the light transmission unit used for calibration calculation processing, among phase differences detected from the light reception signals, the phase difference detected from the light reception signals having an amplitude equal to or greater than a predetermined value is determined as the phase difference corresponding to the lowest light transmission frequency, and based on the determined phase difference corresponding to the lowest light transmission frequency, uncertainty elimination processing is performed with respect to the phase difference corresponding to another light transmission frequency other than the lowest light transmission frequency. (14)

[0385] The distance measuring device according to any one of (8) to (13), further comprising:

[0386] The guide display processing unit performs display processing of a guide image, wherein the guide image guides a composition that satisfies a condition that the distance measurement points are in a specific positional relationship with each other. (15)

[0388] A calibration method for a distance measuring device, wherein the distance measuring device utilizes a light emitting unit that emits light and a light receiving sensor having a plurality of pixels that receive light emitted from the light emitting unit and reflected by a target object, and performs distance measurement using an indirect Time of Flight method based on a light reception signal from the light receiving sensor, the calibration method comprising:

[0389] As calibration calculation processing for obtaining correction parameters of distance information calculated by the indirect ToF method, calculation processing is performed using the condition that respective distance measurement points projected onto a plurality of pixels are in a specific positional relationship with each other.

[0390] Reference Symbols List

[0391] 1, 1A distance measuring device

[0392] 2 Light emitting unit

[0393] 3 sensor units

[0394] 4 lenses

[0395] 5 Phase difference detection unit

[0396] 6 Computing Units

[0397] 7 Amplitude detection unit

[0398] 8, 8A control unit

[0399] 8a, 8aA Calibration calculation unit

[0400] 9 storage units

[0401] 9a Parameter Information

[0402] 10 Display unit

[0403] 11 Operating unit

[0404] Ob target object

[0405] Ls irradiation light

[0406] Lr reflected light

[0407] 20 tablets

[0408] W Frame

[0409] Ar plane imaging area.

Claims

1. A distance measuring device, comprising: a light emitting unit, emitting light; a light receiving sensor for receiving light emitted from the light emitting unit and reflected by a target object; as well as a calibration calculation unit that performs calculation processing as a calibration calculation processing for obtaining correction parameters for distance information calculated by an indirect ToF method based on a light reception signal of the light reception sensor, using the light reception signal of the light reception sensor when the light transmission unit transmits light at a first light transmission frequency and the light reception signal of the light reception sensor when the light transmission unit transmits light at a second light transmission frequency different from the first light transmission frequency.

2. The distance measuring device according to claim 1, wherein: The calibration calculation unit The calculation process is performed based on a phase difference between light transmission and light reception, the phase difference being detected based on the light reception signal, and the correction parameter is obtained.

3. The distance measuring device according to claim 2, wherein: The calibration calculation unit An uncertainty elimination process is performed on the phase difference in units of 2π to eliminate uncertainty.

4. The distance measuring device according to claim 3, wherein: The calibration calculation unit When light emission is performed at the lowest light emission frequency among the light emission frequencies of the light emission unit used for the calibration calculation processing, among the phase differences detected from the light reception signal, the phase difference detected from the light reception signal having an amplitude equal to or greater than a predetermined value is determined as the phase difference corresponding to the lowest light emission frequency, and based on the determined phase difference corresponding to the lowest light emission frequency, a process of eliminating the uncertainty associated with the phase differences corresponding to light emission frequencies other than the lowest light emission frequency is performed.

5. The distance measuring device according to claim 1, wherein: The calibration calculation unit The calibration calculation process is executed based on the elapsed time from the previous execution.

6. The distance measuring device according to claim 1, wherein: When a distance measurement instruction is given during execution of the calibration calculation process, the calibration calculation unit interrupts the calibration calculation process and performs processing for distance measurement.

7. A calibration method in a distance measuring device, the distance measuring device comprising: a light emitting unit, emitting light; and a light receiving sensor that receives light emitted from the light emitting unit and reflected by a target object, and performs distance measurement by an indirect ToF method based on a light receiving signal of the light receiving sensor, the calibration method comprising: As a calibration calculation process for obtaining correction parameters for the distance information calculated by the indirect ToF method, calculation processing is performed using a light receiving signal of the light receiving sensor when the light emitting unit transmits light at a first light emitting frequency, and a light receiving signal of the light receiving sensor when the light emitting unit transmits light at a second light emitting frequency different from the first light emitting frequency.

8. A distance measuring device, comprising: a light emitting unit, emitting light; a light receiving sensor comprising a plurality of pixels receiving light emitted from the light emitting unit and reflected by the target object; as well as A calibration calculation unit performs calibration calculation processing as a calibration calculation processing for obtaining correction parameters for distance information calculated by an indirect ToF method based on a light reception signal of the light reception sensor, using a condition that corresponding distance measurement points projected onto a plurality of the pixels are in a specific positional relationship with each other.

9. The distance measuring device according to claim 8, wherein: The calibration calculation unit The calibration calculation process is performed using a condition that the distance measurement points are located on an object having a known shape relative to each other.

10. The distance measuring device according to claim 8, wherein: The calibration calculation unit As the calibration calculation processing, calculation processing is performed using the light reception signal of the light receiving sensor when the light emitting unit transmits light at a first light transmission frequency, and the light reception signal of the light receiving sensor when the light emitting unit transmits light at a second light transmission frequency different from the first light transmission frequency.

11. The distance measuring device according to claim 8, wherein: The calibration calculation unit A calculation process is performed based on a phase difference between light transmission and light reception, the phase difference being detected based on the light reception signal, and the correction parameter is obtained.

12. The distance measuring device according to claim 11, wherein: The calibration calculation unit An uncertainty elimination process is performed on the phase difference in units of 2π to eliminate uncertainty.

13. The distance measuring device according to claim 12, wherein: The calibration calculation unit When light emission is performed at the lowest light emission frequency among the light emission frequencies of the light emission unit used for the calibration calculation processing, among the phase differences detected from the light reception signals, the phase difference detected from the light reception signals having an amplitude equal to or greater than a predetermined value is determined as the phase difference corresponding to the lowest light emission frequency, and based on the determined phase difference corresponding to the lowest light emission frequency, a process of eliminating the uncertainty associated with the phase difference corresponding to another light emission frequency other than the lowest light emission frequency is performed.

14. The distance measuring device according to claim 8, further comprising: The guide display processing unit performs display processing of a guide image for guiding a composition that satisfies a condition that the distance measurement points are in a specific positional relationship with each other.

15. A calibration method for a distance measuring device, the method comprising: utilizing a light emitting unit that emits light and a light receiving sensor that includes a plurality of pixels and receives light emitted from the light emitting unit and reflected by a target object; and performing distance measurement using an indirect ToF method based on a light reception signal from the light receiving sensor, the method comprising: As calibration calculation processing for obtaining correction parameters of distance information calculated by the indirect ToF method, calculation processing is performed using a condition that respective distance measurement points projected onto the plurality of pixels are in a specific positional relationship with each other.

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