JP5180502B2 - Ranging device and ranging method - Google Patents

Description

  The present invention relates to a distance measuring device and a distance measuring method. For example, a phase delay of reflected light from a detection object irradiated with modulated light is detected for each pixel of an image sensor to detect a three-dimensional object. The present invention relates to a distance measuring device and a distance measuring method suitable for detecting a structure.

  As a method for measuring the distance to an object to be detected, a TOF (Time Of Flight) type light wave distance measuring method is known.

  As shown in FIG. 17, an apparatus using this method is composed of an LED array, for example, and a light source 200 that emits intensity-modulated light (modulated light), and a target that is irradiated by the modulated light emitted from the light source 200. An image sensor 204 that receives reflected light from the detection object 202 and an optical system 206 that forms an image of the reflected light on the image sensor 204 are provided.

  For example, when the modulated light emitted from the light source 200 to the detected object 202 is intensity-modulated at a high frequency of 20 MHz, the wavelength is 15 m. Therefore, if the light reciprocates a distance of 7.5 m, the phase of one cycle is obtained. There will be a delay.

  Here, the phase delay of the reflected light with respect to the modulated light will be described with reference to FIG.

As shown in FIG. 18, the reflected light R is delayed in phase by φ with respect to the modulated light W. In order to detect this phase delay φ, the reflected light R is sampled at equal intervals, for example, four times in one period of the modulated light W. For example, assuming that the sampling values of the reflected light R when the phase of the modulated light W is 0 °, 90 °, 180 °, and 270 ° are A0, A1, A2, and A3, respectively, the phase delay φ is given by the following equation. .
φ = arctan {(A3-A1) / (A0-A2)}

  The reflected light from the object to be detected 202 is imaged on the light receiving surface of the image sensor 204 via the optical system 206. A plurality of pixels (photodiodes) are two-dimensionally arranged on the light receiving surface of the image sensor 204, and the three-dimensional structure of the detected object 202 is detected by obtaining the phase delay φ according to the above equation for each pixel. it can.

  For example, Patent Document 1 has been proposed as a distance measuring device using the above-described principle.

  The distance measuring apparatus according to Patent Document 1 exposes a plurality of patterns by shifting reflected light from an object to be detected by opening / closing phases of a charge sweep gate (overflow drain gate: OFDG) or a read gate of an image sensor. Ranging is performed by receiving light during the period.

  Specifically, referring to FIG. 20 and FIGS. 21A to 21D, first, in the first frame, based on the falling edge of the synchronization signal Sa (step S1: see FIG. 21A), the modulated light W from the light source 200 is displayed. Is emitted (step S <b> 2), and the reflected light R from the detected object 202 irradiated by the modulated light W is incident on the image sensor 204. As shown in FIG. 21A, the image sensor 204 is positioned at the center of the first exposure period Tr when it is delayed by a time T1 from the falling edge of the synchronization signal Sa, that is, when the phase of the modulated light R becomes 0 °. Further, the period of each exposure period Tr is adjusted to 2π.

  Therefore, in the first frame, the amount of reflected light R when the phase of the modulated light W is 0 ° is photoelectrically converted and accumulated in the image sensor 204 (step S3). The charge accumulated in the image sensor 204 is transferred in the next second frame to be converted into an analog signal, further digitally converted (step S4), and sampling of the reflected light R when the phase of the modulated light is 0 °. The value A0 is stored in the buffer memory (step S5). At this stage, the emission of the modulated light W from the light source 200 is completed (step S6).

  Thereafter, in the next third frame, based on the falling edge of the synchronization signal Sa (step S7: see FIG. 21B), the modulated light W is emitted again from the light source 200 (step S8) and irradiated by the modulated light W. Reflected light R from the object to be detected 202 enters the image sensor 204. As shown in FIG. 21B, the image sensor 204 has the first exposure period Tr at the time when it is delayed by the time T2 (> T1) from the falling edge of the synchronization signal Sa, that is, when the phase of the modulated light W becomes 90 °. Adjustment is made so that the center is positioned, and further, the period of each exposure period Tr is adjusted to 2π.

  Accordingly, in the third frame, the light amount of the reflected light R when the phase of the modulated light W is 90 ° is photoelectrically converted and accumulated in the image sensor 204 (step S9). The charge accumulated in the image sensor is transferred in the next fourth frame to be converted into an analog signal, which is further digitally converted (step S10), and the reflected light R is sampled when the phase of the modulated light W is 90 °. The value A1 is stored in the buffer memory (step S11). At this stage, the emission of the modulated light W from the light source 200 ends (step S12).

  Thereafter, in the next fifth frame, based on the falling edge of the synchronization signal Sa (step S13: see FIG. 21C), the modulated light W is emitted again from the light source 200 (step S14) and irradiated by the modulated light W. Reflected light R from the object to be detected 202 enters the image sensor 204. As shown in FIG. 21C, the image sensor 204 has the first exposure period Tr at the time when it is delayed by the time T3 (> T2) from the fall of the synchronization signal Sa, that is, when the phase of the modulated light W is 180 °. Adjustment is made so that the center is positioned, and further, the period of each exposure period Tr is adjusted to 2π.

  Accordingly, in the fifth frame, the light amount of the reflected light R when the phase of the modulated light W is 180 ° is photoelectrically converted and accumulated in the image sensor 204 (step S15). The charge accumulated in the image sensor 204 is transferred in the next sixth frame to be converted into an analog signal, further digitally converted (step S16), and the reflected light R when the phase of the modulated light W is 180 °. The sampling value A2 is stored in the buffer memory (step S17). At this stage, the emission of the modulated light W from the light source 200 ends (step S18).

  Thereafter, in the next seventh frame, based on the falling edge of the synchronizing signal Sa (step S19: see FIG. 21D), the modulated light W is emitted again from the light source 200 (step S20), and is irradiated with the modulated light W. Reflected light R from the object to be detected 202 enters the image sensor 204. As shown in FIG. 21D, the image sensor 204 has the first exposure period Tr at the time when it is delayed by the time T4 (> T3) from the falling edge of the synchronization signal Sa, that is, when the phase of the modulated light W becomes 270 °. Adjustment is made so that the center is positioned, and further, the period of each exposure period Tr is adjusted to 2π.

  Therefore, in the seventh frame, the light amount of the reflected light R when the phase of the modulated light W is 270 ° is photoelectrically converted and accumulated in the image sensor 204 (step S21). The charge accumulated in the image sensor 204 is transferred in the next eighth frame to be converted into an analog signal, further digitally converted (step S22), and sampling of the reflected light R when the phase of the modulated light is 270 °. The value A3 is stored in the buffer memory (step S23). At this stage, the emission of the modulated light W from the light source 200 ends (step S24).

  Then, the phase delay φ of the reflected light R is obtained based on the sampling values A0, A1, A2, A3 in the buffer memory, and the distance to the detected object 202 is obtained based on the phase delay φ ( Step S25).

Japanese Patent No. 3758618

  By the way, when the distance to the object to be detected is long, the calculated distance may show an invalid value. In such a case, the wavelength of the modulated light depends on the control signal from the CPU or the user's operation input. May be changed. That is, the wavelength of the modulated light may be changed based on an external control signal. In such a case, the center position of the exposure period is usually determined in accordance with the changed wavelength of the modulated light. However, a change in an integer level (integer multiple) with respect to a preset period of the exposure period. (Division or multiplication by an integer multiple) is easy, but there is a problem that dedicated calibration is required when the change occurs at the real number level.

  The present invention has been made in consideration of such problems, and when the distance to the object to be detected is long, the distance to the object to be detected can be accurately measured without performing a dedicated calibration. An object of the present invention is to provide a distance measuring device and a distance measuring method capable of performing the above.

A distance measuring device according to a first aspect of the present invention includes a light emitting unit that emits modulated light whose intensity is modulated at each of a plurality of light emission start timings, and a light receiving unit that receives reflected light from an object irradiated by the modulated light a means, a calculating means for calculating the distance from the phase difference of the reflected light and the modulated light to said object to be detected, the modulated light is intensity-modulated at a constant frequency, the light receiving means The time length from the light emission start timing to the light reception start time of the reflected light is changed based on the number of times of the light emission start timing and the wavelength of the waveform of the modulated light intensity-modulated at the frequency , respectively. a distance measuring apparatus for receiving the reflected light from the object to be detected, the light receiving means, the light quantity of the reflected light at the set exposure time for each constant cycle the light detection start time as a reference An imaging unit that performs sampling, a timing control unit that changes a time length from the light emission start timing to the light reception start point of the reflected light based on the number of times of the light emission start timing and the wavelength in the modulated light, and an external An exposure timing change unit that changes a cycle of the exposure period based on a control signal from the light source, and the light emitting means modulates the modulation based on the cycle of the exposure period changed by the exposure timing change unit A wavelength changing unit that changes the wavelength of the light, and the timing control unit is configured to determine a time length until the light receiving start time based on the number of times of the light emission start timing and the changed wavelength of the modulated light. characterized Rukoto changing the of.

  Thereby, when the distance to the object to be detected is long, the distance to the object to be detected can be accurately measured without performing dedicated calibration.

In this case, said wavelength in said modulated light corresponding to the changed cycle length of the exposure period, the information of the light detection start timing has a memory table registered is stored, the wavelength changing unit, said memory Based on the stored information of the table, the wavelength in the modulated light is changed, the timing control unit based on the number of times of the light emission start timing and the information of the table stored in the memory The time length until the light reception start time may be changed. Access to the table may be performed using an identification code corresponding to the changed period of the exposure period.

  Thereby, the wavelength changing unit changes the wavelength with reference to the table when changing each wavelength of the plurality of modulated lights based on the changed exposure period, and the timing control unit is configured to change the light reception start time point. When the time length up to is changed, the time length can be changed with reference to the table, so that the processing time can be shortened.

Of course, based on the changed period of the exposure period, the wavelength calculator that calculates the wavelength of the modulated light, and the wavelength changer, the wavelength calculator calculates the wavelength of the modulated light . The timing control unit changes the time length until the light reception start point based on the number of times of the light emission start timing and the wavelength obtained by the wavelength calculation unit. Also good. In this case, there is no need to provide a memory or memory area for storing the table.

In the first aspect of the present invention, at least the following processing may be performed. That is,
(1) The light emitting means emits modulated light over a predetermined period based on the first light emission start timing, emits modulated light over a predetermined period based on the second light emission start timing,
(2) The light receiving unit receives the first reflected light from the detected object irradiated by the modulated light from the first light reception start time based on the first light emission start timing for the predetermined period. And receiving the second reflected light from the detected object irradiated by the modulated light over the predetermined period from the second light reception start time based on the second light emission start timing,
(3) The calculation means is configured to obtain the detection object based on at least a phase difference between the first modulated light and the first reflected light and a phase difference between the second modulated light and the second reflected light. Calculate the distance.

  In this case, the light receiving means samples the light amount of the first reflected light during an exposure period set for each predetermined period with the first light reception start time as a reference, and uses the first light reception start time as a reference. The light quantity of the second reflected light is sampled during the exposure period set for each predetermined period, and the calculation means integrates a value obtained by integrating the sampling result of the light quantity of the first reflected light over the predetermined period. The phase difference between the modulated light and the second reflected light may be a value obtained by integrating the sampling results of the light quantity of the second reflected light over the predetermined period.

Next, a distance measuring method according to a second aspect of the present invention includes a light emitting step of emitting modulated light whose intensity is modulated at each of a plurality of light emission start timings, and reflected light from an object irradiated with the modulated light. a light receiving step of receiving, and a calculation step of calculating the distance from the phase difference of the modulated light and the reflected light to the object to be detected, the modulated light is intensity-modulated at a constant frequency, the The light receiving step changes the time length from the light emission start timing to the light reception start time of the reflected light based on the number of times of the light emission start timing and the wavelength of the waveform in the modulated light intensity-modulated at the frequency. wherein by a distance measuring method for receiving the reflected light from the object to be detected, the light receiving step, set exposure time for each constant cycle the light detection start time as a reference Imaging step of sampling the amount of the reflected light, and the time length from the light emission start timing to the light reception start time of the reflected light based on the number of times of the light emission start timing and the wavelength of the modulated light, respectively A timing control step for changing, and an exposure timing changing step for changing a cycle of the exposure period based on a control signal from the outside, wherein the light emission step is changed in the exposure timing changing step. A wavelength changing step of changing the wavelength in the modulated light based on a period of the period, the timing control step based on the number of times of the light emission start timing and the changed wavelength in the modulated light, The time length until the light reception start time is changed .

  Thereby, when the distance to the object to be detected is long, the distance to the object to be detected can be accurately measured without performing dedicated calibration.

Moreover, using said wavelength in corresponding to the period of change length of the exposure period the modulated light, a table in which information of light detection start timing is registered, the wavelength changing step, based on the information of the table, the change the wavelength in the modulated light, wherein the timing control step includes a number of the light emission start timing, based on the information of the table may be changed time length until the light detection start time. The table may be accessed using an identification code corresponding to the changed period of the exposure period.

Alternatively, the wavelength calculating step of calculating the wavelength in the modulated light based on the changed period of the exposure period, the wavelength changing step, the wavelength in the modulated light in the wavelength calculating step The timing is changed to the obtained wavelength, and the timing control step changes the time length until the light reception start time based on the number of times of the light emission start timing and the wavelength obtained in the wavelength calculation step. It may be.

In the second aspect of the present invention, at least the following processing may be performed. That is,
(1) The light emitting step emits modulated light over a predetermined period based on a first light emission start timing, emits modulated light over a predetermined period based on a second light emission start timing,
(2) The light receiving step receives first reflected light from the detected object irradiated by the modulated light from the first light receiving start time based on the first light emission start timing for the predetermined period. And receiving the second reflected light from the detected object irradiated by the modulated light over the predetermined period from the second light reception start time based on the second light emission start timing,
(3) In the calculation step, based on at least the phase difference between the first modulated light and the first reflected light and the phase difference between the second modulated light and the second reflected light, Calculate the distance.

  In this case, the light receiving step samples the light quantity of the first reflected light during an exposure period set for each predetermined period with the first light reception start time as a reference, and the first light reception start time as a reference. The amount of the second reflected light is sampled during the exposure period set for each predetermined period, and the calculation step is configured to add a value obtained by integrating the sampling result of the amount of the first reflected light over the predetermined period to the modulated light. The phase difference between the modulated light and the second reflected light may be a value obtained by integrating the sampling results of the light quantity of the second reflected light over the predetermined period.

  As described above, according to the distance measuring apparatus and the distance measuring method according to the present invention, when the distance to the detected object is long, the distance to the detected object can be accurately determined without performing dedicated calibration. Can be measured.

  Embodiments of a distance measuring device and a distance measuring method according to the present invention will be described below with reference to FIGS.

  First, as shown in FIG. 1, a distance measuring device according to the first embodiment (hereinafter referred to as a first distance measuring device 10A) includes a light emitting means 14 that emits intensity-modulated modulated light 12, and a modulated light. A light receiving means 20 for receiving the reflected light 18 from the detected object 16 irradiated by the light 12; a calculating means 22 for calculating a distance to the detected object 16 from the phase difference between the modulated light 12 and the reflected light 18; And a synchronization signal generator 24 for generating a synchronization signal Sa indicating the start.

  The light emitting means 14 includes a light emitting unit 26 and a light emission control unit 28 that modulates the intensity of the light emitted from the light emitting unit 26 and emits the modulated light 12. Irradiation of the modulated light 12 is started with, for example, the falling time t0 of the synchronization signal Sa as a reference time. As an example, when a certain period of time when the reflected light 18 is received by the light receiving means 20 after emitting the modulated light 12 is one frame, for example, a synchronization signal in an odd frame such as the first frame, the third frame, or the fifth frame. For example, the irradiation of the modulated light 12 is started at the light emission start timing at the falling time t0 of Sa.

  The light emitting unit 26 is configured by arranging a plurality of LEDs. The light emission control unit 28 controls the light emitting unit 26 based on the input of the synchronization signal Sa from the synchronization signal generating unit 24, for example, the light emitted from the light emitting unit 26, for example, the light emission intensity is an intensity along a sine curve. The modulated modulated light 12 is emitted.

  The light receiving means 20 includes an imaging device 30, an optical system 32 that forms an image of the reflected light 18 on the light receiving surface of the imaging device 30, an imaging device control unit 34 for driving the imaging device 30, and imaging from the imaging device 30. An analog signal processing unit 36 that processes the signal Sb into an analog image signal Sc, an A / D conversion unit 38 that digitally converts the image signal Sc into image data Dc, and a buffer memory 40 that stores the image data Dc. And have.

  The image sensor control unit 34 controls the image sensor 30 so as to sample the light amount of the reflected light 18 in an exposure period set at regular intervals with reference to, for example, the time point of falling of the input synchronization signal Sa.

  Specifically, the image sensor control unit 34 generates an exposure pulse having a constant pulse width and a constant pulse period based on, for example, the falling time t0 of the input synchronization signal Sa. Unit 100, transfer pulse generation unit 102 for generating a read pulse and a transfer pulse based on the falling time t0, and driving the image pickup device 30 using the pulse width of the exposure pulse as an exposure period. And a drive unit 104 that drives the image sensor 30 based on the pulse. Therefore, in this example, the pulse width of the exposure pulse and the exposure period are matched. Of course, the exposure pulse may be an impulse pulse (so-called trigger pulse). In this case, the drive unit 104 drives the image sensor 30 by setting a certain exposure period from the input time of the trigger pulse.

  As shown in FIG. 2, the imaging element 30 includes a light receiving unit 42 and a horizontal transfer path 44 provided adjacent to the light receiving unit 42. In the light receiving unit 42, a large number of pixels 46 (photodiodes) that photoelectrically convert charges into an amount corresponding to the amount of incident light are arranged in a matrix, and among the large number of pixels 46, the pixels 46 arranged in the column direction are arranged. A plurality of common vertical transfer paths 48 are arranged in the row direction. The horizontal transfer path 44 is common to a large number of vertical transfer paths 48.

  Here, a procedure for reading out charges from the pixels 46, for example, a procedure for reading out charges based on the concept of a frame used in video output will be described. As shown in FIGS. 3A and 3B, for example, each pixel 46 in the first frame is shown in FIG. Receives the reflected light 18 and generates and accumulates charges (exposure). At this time, instead of exposing the entire first frame, an exposure period is set at a necessary timing, and exposure is performed in each exposure period. This exposure period is set by driving an electro-optical shutter or a CCD electronic shutter installed in the image sensor 30 based on a control signal from the image sensor control unit 34. An overflow drain region 50 is formed adjacent to each pixel 46, and by applying a predetermined voltage to the discharge electrode 52, the potential potential of the overflow drain region 50 is lowered, and the charge accumulated in the pixel is discharged. Be able to.

  Then, charge transfer is performed in the next second frame. Specifically, in the vertical blanking period of the second frame, for example, as shown in FIGS. 4A and 4B, a predetermined voltage is applied to the vertical transfer electrode 54 corresponding to one packet of the vertical transfer path 48. , The potential potential of the packet falls below the potential potential of the pixel 46. As a result, the charge accumulated in the pixel 46 flows into the vertical transfer path 48 side. Thereafter, the potential is returned to the original state, and a charge voltage is applied to the vertical transfer electrode 54 in the horizontal blanking period to transfer charges toward the horizontal transfer path 44 as shown in FIG. When the charge is transferred to the horizontal transfer path 44, the transfer voltage is applied to the horizontal transfer electrode in the horizontal scanning period, whereby the charge is transferred toward the output unit 56. Then, in the output unit 56, the voltage signal corresponding to the amount of charge is converted into series and output as the imaging signal Sb.

  By sequentially repeating the horizontal blanking period and the horizontal scanning period in the second frame, the charges accumulated in each pixel 46 are sequentially transferred to the output unit 56 via the vertical transfer path 48 and the horizontal transfer path 44. Is output as the imaging signal Sb.

  In the second frame described above, exposure at each pixel 46 may be stopped, or exposure may be performed.

  The image signal Sb from the image sensor 30 is processed into an analog image signal Sc by the analog signal processing unit 36. The image signal Sc is digitally converted into image data Dc by the A / D converter 38. The image data Dc has a data structure in which sampling values obtained by sampling the reflected light 18 at a necessary timing (exposure period) are arranged corresponding to each pixel 46.

  The buffer memory 40 stores four types of image data Dc (first image data Dc1 to fourth image data Dc4) in accordance with the above-described TOF method. The first image data Dc1 has a data structure in which sampling values when the reflected light 18 is sampled at a timing when the phase of the modulated light 12 is, for example, 0 ° are arranged corresponding to the pixels 46. Similarly, the second image data Dc2, the third image data Dc3, and the fourth image data Dc4 are obtained when the reflected light 18 is sampled at the timing when the phase of the modulated light 12 is 90 °, 180 °, and 270 °, respectively. The sampling value has a data structure arranged corresponding to each pixel 46.

  The calculation means 22 has a distance calculation unit 58 that calculates the distance to the detected object 16 corresponding to each pixel 46 based on the first image data Dc1 to the fourth image data Dc4.

  A calculation algorithm in the distance calculation unit 58, in particular, a calculation method of the distance in one pixel 46 will be described with reference to FIG. When the locus of the modulated light 12 is considered as a circle 60 centered on the origin, the reflected light 18 is point P1 when the phase of the modulated light 12 is 0 ° (360 °), 90 °, 180 °, and 270 °, respectively. , P2, P3, P4, and when the coordinates of the point P1 are (A, -B), the coordinates of P2 are (B, A), the coordinates of P3 are (-A, B), and the coordinates of P4 are (-B, -A).

Since these coordinates can be converted into a right triangle 62 in FIG. 5, the phase delay φ of the reflected light 18 with respect to the modulated light 12 can be obtained by the following equation (1).
φ = arctan {(B − (− B)) / (A − (− A))} (1)

Here, A corresponds to the sampling value S2 of the second image data Dc2, -A corresponds to the sampling value S4 of the fourth image data Dc4, B corresponds to the sampling value S3 of the third image data Dc3,- Since B corresponds to the sampling value S1 of the first image data Dc1, equation (1) can be rewritten as the following equation (2).
φ = arctan {(S3-S1) / (S2-S4)} (2)

When one period of the modulated light 12 is T, the delay time τ from when the modulated light 12 is emitted until the reflected light 18 is received is
τ = T × (φ / 2π)
Can be obtained.

This delay time τ is a reciprocating distance of the distance L to the detected object 16, and travels at a speed of light speed c between them, so the distance L is
L = (τ × c) / 2
Can be obtained.

  In the distance calculation unit 58, the above-described algorithm is incorporated as software, for example, and the above-described algorithm is performed on each pixel 46, and a distance corresponding to each pixel 46 is calculated. As a result, the detected object 16 The three-dimensional structure is detected.

  The first distance measuring device 10A includes an exposure timing changing unit 64 that changes the cycle Tt (see FIGS. 7 and 9) of the exposure period Tr based on a control signal from the outside. A wavelength changing unit 66 that changes the wavelength (see FIGS. 7 and 9) of the modulated light 12 based on the period Tt of the exposure period Tr changed by the timing changing unit 64, the number of times of light emission start timing, and the modulation light 12 And a timing control unit 68 that changes the time length from the light emission start timing to the light reception start time of the reflected light 18 based on the wavelength.

  The exposure timing changing unit 64 receives an instruction signal from the operation unit 70 (an instruction signal indicating whether the time length of one frame is shortened or lengthened by a user's operation instruction), or sampling accumulated in the buffer memory 40. An instruction signal from the exposure timing calculation unit 72 that calculates whether to shorten or lengthen the time length of one frame based on the value (instruction signal to shorten or lengthen the time length of one frame) Based on the above, the cycle Tt of the exposure period Tr is changed.

  As the period Tt of the exposure period Tr, several kinds of periods Tt (at least two kinds of periods) having different time lengths are prepared in advance, and when an instruction signal for shortening one frame is input, A cycle Tt that is one step shorter than the cycle Tt of the exposure period Tr is selected, or a cycle Tt that is one step longer than the cycle Tt of the current exposure period Tr is selected when an instruction signal for extending one frame is input. To do.

  By adopting this method, the wavelength λ of the modulated light 12 can be set in accordance with the changed period Tt of the exposure period Tr. Therefore, an integer level with respect to the preset period Tt of the exposure period Tr. The cycle Tt of the exposure period Tr can be changed by (multiplication by an integral multiple or multiplication by an integral multiple), and the circuit configuration can be simplified.

  The timing control unit 68 changes the light reception start change unit for changing the light reception start reference time in the image sensor 30 according to the number of times of the light emission start timing based on the cycle Tt of the exposure period Tr changed by the exposure timing change unit 64. 74, a delay time correction unit 76 for correcting a delay time from the light reception start reference time to the light reception start timing according to the number of times of the light emission start timing based on the changed cycle Tt of the exposure period Tr, and the changed exposure The memory 80 stores an information table 78 in which information on the wavelength corresponding to the period Tt of the period Tr, light reception start timing, and delay time is registered. The light reception start changing unit 74 and the delay time correcting unit 76 are incorporated in the image sensor control unit 34. That is, the light reception start changing unit 74 delays the exposure pulse from the exposure pulse generating unit 100 until the changed light reception start reference time, and the delay time correcting unit 76 further delays the exposure pulse by the corrected delay time. . Here, the delay time from the reference time of the light emission start timing set by the light reception start change unit 74 to the reference time of the light reception start timing is the first delay time Te, and the delay time set by the delay time correction unit 76 is the first delay time. It is defined as 2 delay time Tf.

  In the above description, light reception is mainly described. However, the charge transfer timing is also changed by the light reception start changing unit 74 and the delay time correcting unit 76. That is, for example, when the light reception start timing is changed in the first frame and the light reception is started, but the charge transfer timing in the next second frame is not changed, the charge transfer is started from the middle of the first frame. This is because inconveniences such as start of the image occur. In addition, since it will be complicated to explain the details up to charge transfer, in the following description, exposure with the image sensor 30 will be mainly described, and the description of charge transfer will be supplemented.

  In this embodiment, an identification code is assigned to each of the plurality of types of exposure periods Tr prepared in advance and corresponds to the period Tt of the exposure period Tr selected by the exposure timing changing unit 64. By transmitting the identification code to the wavelength changing unit 66, the light reception start changing unit 74, and the delay time correcting unit 76, the wavelength changing unit 66, the light receiving start changing unit 74, and the delay time correcting unit 76 are currently changed in the exposure period. The period Tt of Tr can be recognized.

  Then, the wavelength changing unit 66 changes the wavelength of the modulated light 12 based on the changed period Tt of the exposure period Tr (selected exposure period) and the information in the information table 78 stored in the memory 80. .

  Since the period Tt of the exposure period Tr after the change can be recognized by the identification code transmitted from the exposure timing changing unit 64 as described above, the information registered in the information table 78 is, for example, as shown in FIG. In addition, the identification code of the period Tt of the exposure period Tr, the information of the wavelength λ corresponding to the identification code (wavelength information), the information related to the first delay time Te (first delay time related information), the second Information related to the delay time Tf (second delay time related information) can be considered.

Incidentally, the wavelength of the modulated light 12 (see FIGS. 7 and 14B) is changed based on the cycle Tt of the exposure period Tr changed by the exposure timing changing unit 64. Here, the modulation in the initial state is performed. When the wavelength of light is λ, the wavelength of modulated light after change is aλ, and the number of light emission start timings is n, the first delay time Te and the second delay time Tf can be obtained by the following arithmetic expressions. .
Te = (a−1) λ + (n−1) λ / 4
Tf = (n−1) (a−1) λ / 4

  Therefore, (a-1) λ is registered as the first delay time related information registered in the information table 78, and the actual first delay time Te is converted into the first delay time related information ( n-1) λ / 4 is added to obtain. Similarly, (a-1) λ / 4 is registered as the second delay time related information registered in the information table 78, and the actual second delay time Tf is related to the second delay time related by the delay time correction unit 76. Information is obtained by multiplying (n-1).

  Here, the processing operation of the first distance measuring device 10A, particularly, the processing operation before changing the cycle Tt of the exposure period Tr will be described with reference to FIG. Since the period Tt of the exposure period Tr is not changed, the wavelength of the modulated light 12 is λ, and the variable a = 1. Accordingly, the first delay time Te increases by λ / 4 according to the number n of light emission start timings, and the second delay time Tf becomes 0 from the above arithmetic expression. Of the identification codes registered in the information table 78, the exposure timing changing unit 64 includes an identification code in which the wavelength information indicates λ and the first delay time related information and the second delay time related information are both 0. The data is transmitted to the wavelength changing unit 66, the light reception start changing unit 74, and the delay time correcting unit 76. As a result, the exposure pulse is only delayed according to the number of light emission start timings in the light reception start changing unit 74, and is not delayed in the delay time correction unit 76.

  Therefore, when the wavelength of the modulated light 12 is λ, as shown in FIG. 7, the image sensor control unit 34 performs the first exposure period when a predetermined period Ta elapses from, for example, the falling point of the synchronization signal Sa. By starting Tr, and further adjusting one period of each exposure period Tr to one wavelength of the modulated light 12, the phase of the modulated light 12 is reflected at any one of 0 °, 90 °, 180 °, and 270 °. When control is performed so that the sampling value of the light 18 is obtained, the light reception start changing unit 74 delays the arrival time of the exposure pulse to the drive unit by λ / 4 based on the number of light emission start timings, thereby modulating light. The sampling values of the reflected light 18 are obtained when the phase of 12 is 0 °, 90 °, 180 °, 270 °.

  Next, the processing operation of the first distance measuring device 10A, particularly the processing operation before changing the cycle Tt of the exposure period Tr will be described with reference to the waveform diagram of FIG. 7 and the flowchart of FIG.

  First, the synchronization signal generator 24 outputs a synchronization signal Sa indicating the first frame (step S101). The light emission control unit 28 emits the modulated light 12 from the light emitting unit 26 based on the falling time point t0 of the synchronization signal Sa (step S102).

  The modulated light 12 emitted from the light emitting unit 26 is applied to the detection object 16, and the reflected light 18 from the detection object 16 is incident on the image sensor 30 via the optical system 32. At this time, since the number n of the light emission start timing is 1, the light reception start changing unit 74 outputs the exposure pulse to the drive unit 104 without delay (step S103). The imaging element 30 is positioned such that the center of the first exposure period Tr is located at a time delayed by the time Ta from the falling time t0 of the synchronization signal Sa of the first frame, that is, when the phase of the modulated light 12 becomes 0 °. Further, the period of each exposure period Tr is adjusted to be the wavelength of the modulated light.

  Therefore, in the first frame, the amount of the reflected light 18 when the phase of the modulated light 12 is 0 ° is photoelectrically converted and accumulated in the image sensor 30 (step S104). Thereafter, the synchronization signal generator 24 outputs a synchronization signal Sa indicating the second frame (step S105). At this time, since the number n of the light emission start timing is 1, the light reception start changing unit 74 outputs the light to the drive unit 104 without delaying the transfer pulse or the like. The electric charge accumulated in the image pickup device 30 is transferred in the second frame to be converted into an analog signal (image signal) (step S106), further digitally converted (step S107), and the phase of the modulated light 12 is 0 °. The sampling value S1 of the reflected light 18 at a certain time is stored in the buffer memory 40 as the first image data Dc1 arranged for each pixel (step S108). At this stage, the emission of the modulated light 12 ends (step S109).

  Next, the synchronization signal generator 24 outputs a synchronization signal Sa indicating the third frame (step S110). The light emission control unit 28 emits the modulated light 12 from the time t0 when the synchronization signal Sa falls (step S111).

  The modulated light 12 emitted from the light emitting unit 26 is applied to the detection object 16, and the reflected light 18 from the detection object 16 is incident on the image sensor 30 via the optical system 32. At this time, since the number n of light emission start timings is 2, the light reception start changing unit 74 delays the exposure pulse by the time λ / 4 and outputs it to the drive unit 104 (step S112). Accordingly, the image sensor 30 detects the first exposure period Tr when the phase of the modulated light 12 becomes 90 °, that is, when the phase of the modulated light 12 is 90 °, which is delayed from the time t0 when the synchronization signal Sa of the generated third frame falls. Is controlled so that the period of each exposure period Tr becomes the wavelength λ of the modulated light.

  Therefore, in the third frame, the light amount of the reflected light 18 when the phase of the modulated light 12 is 90 ° is photoelectrically converted and accumulated in the image sensor 30 (step S113). Thereafter, the synchronization signal generator 24 outputs a synchronization signal Sa indicating the fourth frame (step S114). At this time, since the number n of light emission start timings is 2, the light reception start changing unit 74 delays the transfer pulse and the like by a time λ / 4 and outputs it to the drive unit 104. The electric charge accumulated in the image pickup device 30 is transferred in the fourth frame to be converted into an analog signal (step S115), further digitally converted (step S116), and reflected when the phase of the modulated light 12 is 90 °. The sampling value S2 of the light 18 is stored in the buffer memory 40 as the second image data Dc2 arranged for each pixel (step S117). At this stage, the emission of the modulated light 12 ends (step S118).

  Next, the synchronization signal generator 24 outputs a synchronization signal Sa indicating the fifth frame (step S119). The light emission control unit 28 emits the modulated light 12 from the time t0 when the synchronization signal Sa falls (step S120).

  The modulated light 12 emitted from the light emitting unit 26 is applied to the detection object 16, and the reflected light 18 from the detection object 16 is incident on the image sensor 30 via the optical system 32. At this time, since the number n of light emission start timings is 3, the light reception start changing unit 74 delays the exposure pulse by time (2λ) / 4 and outputs it to the drive unit 104 (step S121). Accordingly, the image pickup device 30 has a first exposure period Tr when the phase of the modulated light 12 becomes 180 °, that is, when it is delayed by the time Ta + (2λ) / 4 from the time t0 when the synchronization signal Sa of 5 frames falls. The center of each exposure period Tr is controlled so that the period of each exposure period Tr becomes the wavelength λ of the modulated light 12.

  Accordingly, in the fifth frame, the light amount of the reflected light 18 when the phase of the modulated light 12 is 180 ° is photoelectrically converted and accumulated in the image sensor 30 (step S122). Thereafter, the synchronization signal generator 24 outputs a synchronization signal Sa indicating the sixth frame (step S123). At this time, since the number n of the light emission start timing is 3, the light reception start changing unit 74 delays the transfer pulse or the like by time (2λ) / 4 and outputs it to the drive unit 104. The charge accumulated in the image sensor 30 is transferred in the sixth frame to be converted into an analog signal (step S124), further converted into a digital signal (step S125), and reflected when the phase of the modulated light 12 is 180 °. The sampling value S3 of the light 18 is stored in the buffer memory 40 as third image data Dc3 arranged for each pixel (step S126). At this stage, the emission of the modulated light 12 ends (step S127).

  Next, the synchronization signal generator 24 outputs a synchronization signal Sa indicating the seventh frame (step S128). The light emission control unit 28 emits the modulated light 12 from the time t0 when the synchronization signal Sa falls (step S129).

  The modulated light 12 emitted from the light emitting unit 26 is applied to the detection object 16, and the reflected light 18 from the detection object 16 is incident on the image sensor 30 via the optical system 32. At this time, since the number n of light emission start timings is 4, the light reception start changing unit 74 delays the exposure pulse by time (3λ) / 4 and outputs it to the drive unit 104 (step S130). Therefore, the image pickup device 30 starts the first exposure period when it is delayed by the time Ta + (3λ) / 4 from the falling time t0 of the synchronization signal Sa of the seventh frame, that is, when the phase of the modulated light 12 becomes 270 °. Control is performed so that the center of Tr is positioned, and further, the period of each exposure period Tr is controlled to be the wavelength λ of the modulated light 12.

  Therefore, in the seventh frame, the light amount of the reflected light 18 when the phase of the modulated light 12 is 270 ° is photoelectrically converted and accumulated in the image sensor 30 (step S131). Thereafter, the synchronization signal generator 24 outputs a synchronization signal Sa indicating the eighth frame (step S132). At this time, since the number n of light emission start timings is 4, the light reception start changing unit 74 delays the transfer pulse or the like by time (3λ) / 4 and outputs it to the drive unit 104. The charge accumulated in the image sensor 30 is transferred in the eighth frame to be converted into an analog signal (step S133), further converted into a digital signal (step S134), and reflected when the phase of the modulated light 12 is 270 °. The sampling value S4 of the light 18 is stored in the buffer memory 40 as the fourth image data Dc4 arranged for each pixel (step S135). At this stage, the emission of the modulated light 12 ends (step S136).

  Then, the distance calculation unit 58 calculates the distance to the detected object 16 based on the first image data Dc1 to the fourth image data Dc4 stored in the buffer memory 40 (step S137).

  Next, the processing operation of the first distance measuring device 10A, particularly the processing operation after changing the cycle Tt of the exposure period Tr will be described with reference to the waveform diagram of FIG.

  First, when the cycle Tt of the exposure period Tr is changed in the exposure timing changing unit 64 based on the instruction signal from the operation unit 70 or the instruction signal from the exposure timing calculation unit 72, the exposure period Tr after the change is changed. An identification code corresponding to the period Tt is transmitted to the wavelength changing unit 66, the light reception start changing unit 74, and the delay time correcting unit 76.

  The wavelength changing unit 66 reads out wavelength information corresponding to the transmitted identification code from among the plurality of wavelength information registered in the information table 78 stored in the memory 80 and supplies the read wavelength information to the light emission control unit 28. The light emission control unit 28 changes the wavelength of the modulated light 12 based on the supplied wavelength information.

  The light reception start changing unit 74 reads out the first delay time related information corresponding to the identification code among the plurality of first delay time related information registered in the information table 78, and further, based on the above-described arithmetic expression. A delay time Te is obtained, and the exposure pulse or the like is delayed by this first delay time Te.

  The delay time correction unit 76 reads out the second delay time related information corresponding to the identification code among the plurality of second delay time related information registered in the information table 78, and further, based on the above-described arithmetic expression, the second delay time related information is read out. A delay time Tf is obtained, and the exposure pulse or the like is delayed by the second delay time Tf.

  Therefore, for example, as shown in FIG. 9, the modulated light 12 having the changed wavelength (aλ) is emitted, and the exposure pulse Tr of the first frame is received by the light reception start changing unit 74 at the first delay time. Since it is delayed by Te (= (a−1) λ) and input to the drive unit 104, the exposure period starts at a time delayed by time (a−1) λ + Ta from the falling time t0 of the synchronization signal Sa. When the phase of the modulated light 12 becomes 0 °, the center of the exposure period Tr is located. As a result, the sampling value S1 of the reflected light 18 when the phase of the modulated light 12 is 0 ° is obtained.

  Next, the exposure pulse of the third frame (n = 2) is delayed by a delay time Te (= (a−1) λ + λ / 4) by the light reception start changing unit 74, and further, the delay time correcting unit 76 Since it is delayed by 2 delay time Tf (= (a-1) λ / 4) and inputted to the drive unit, it is delayed by time {(5a / 4) −1} λ + Ta from the falling time t0 of the synchronization signal Sa. The exposure period Tr is started at this point, and the center of the exposure period Tr is located when the phase of the modulated light 12 becomes 90 °. As a result, the phase of the reflected light 18 at the phase of the modulated light 12 is 90 °. A sampling value S2 is obtained.

  Next, the exposure pulse of the fifth frame (n = 3) is delayed by the delay time Te (= (a−1) λ + (2λ) / 4) by the light reception start changing unit 74, and further the delay time correcting unit 76. Is delayed by the second delay time Tf (= 2 (a-1) λ / 4) and input to the drive unit 104, and therefore, the time {(3a / 2) − from the falling time t0 of the synchronization signal Sa. The exposure period Tr is started when 1} λ + Ta is delayed, and the center of the exposure period Tr is positioned when the phase of the modulated light 12 becomes 180 °. As a result, the phase of the modulated light 12 is 180 °. A sampling value S3 of the reflected light 18 is obtained.

  Next, the exposure pulse of the seventh frame (n = 4) is delayed by the first delay time Te (= (a−1) λ + (3λ) / 4) by the light reception start changing unit 74, and further delay time correction is performed. Since the signal is delayed by the second delay time Tf (= 3 (a-1) λ / 4) by the unit 76 and input to the driving unit 104, the time {(7a / 4) from the time t0 when the synchronization signal Sa falls. ) -1} The exposure period Tr is started when λ + Ta is delayed, and the center of the exposure period Tr is located when the phase of the modulated light 12 reaches 270 °. As a result, the phase of the modulated light 12 is changed. A sampling value S4 of the reflected light 18 at 270 ° is obtained.

  In this way, when the reflected light 18 is sampled at the central point of each exposure period Tr after the period Tt is changed, the prescribed four phases (180 °, 90 °, 0 °, 270 °) of the modulated light 12 are obtained. ) And the distance calculation by the distance calculation unit 58 can be performed with high accuracy.

  In the first distance measuring apparatus 10A, the exposure timing changing unit 64 changes the cycle Tt of each exposure period Tr, and the wavelength changing unit 66 changes the modulated light 12 based on the changed cycle Tt of the exposure period Tr. , The light reception start changing unit 74 changes the light reception start timing in the image sensor 30 based on the changed period Tt of the exposure period Tr, and the delay time correction unit 76 uses the delay time of the light reception start timing. Therefore, the wavelength of the modulated light 12 can be set in accordance with the cycle Tt of the exposure period Tr. As a result, an integer level (with respect to the preset cycle Tt of the exposure period Tr) The exposure timing can be changed by dividing by an integral multiple or multiplying by an integral multiple, and the circuit configuration can be simplified. Of course, even when the distance to the detected object 16 is long, calibration is not required and the distance to the detected object 16 can be measured accurately.

  In this case, an information table 78 in which the wavelength information of the modulated light 12 corresponding to the identification code of the period Tt of the exposure period Tr, the first delay time related information, and the second delay time related information is registered is used. Based on the information, the wavelength of the modulated light 12 and the light reception start timing are changed, and further, the delay time of the light reception start timing is corrected, so that the modulation light 12 based on the changed period Tt of the exposure period Tr is changed. Since the wavelength, the first delay time Te, and the second delay time Tf can be easily obtained by accessing the information table 78 without using complicated calculations, the processing time can be shortened.

  Next, a distance measuring apparatus according to the second embodiment (hereinafter referred to as a second distance measuring apparatus 10B) will be described with reference to FIG.

  As shown in FIG. 10, the second distance measuring device 10B has substantially the same configuration as the first distance measuring device 10A described above, but differs in the following points.

  First, the exposure timing changing unit 64 sets the cycle Tt of the current exposure period Tr when the cycle Tt of the initial exposure period Tr is preset and an instruction signal for shortening the cycle Tt of the exposure period Tr is input. When an instruction signal for shortening the period Tr of the exposure period Tr is input by shortening it by 1 / m (m: integer), the period Tt of the current exposure period Tr is set by 1 / m (m: integer). Lengthen.

  The second distance measuring device 10B includes a wavelength calculation unit 82 that calculates the wavelength of the modulated light 12 based on the changed period Tt of the exposure period Tr, and a first delay calculation unit that calculates the first delay time Te. 84 and a second delay calculation unit 86 for calculating the second delay time Tf.

  The wavelength calculator 82 calculates the wavelength of the modulated light 12 based on the changed period Tt of the exposure period Tr. The wavelength information obtained by the calculation is supplied to the light emission control unit 28. The first delay calculation unit 84 calculates the second delay time Te based on the above-described calculation formula of the first delay time Te based on the changed cycle Tt of the exposure period Tr. The first delay time Te obtained by the calculation is supplied to the light reception start changing unit 74. The second delay calculator 86 calculates the second delay time Tf based on the above-described calculation formula of the second delay time Tf based on the changed cycle Tt of the exposure period Tr. The second delay time Tf obtained by the calculation is supplied to the delay time correction unit 76. The light reception start changing unit 74 and the delay time correcting unit 76 are the same as those in the first distance measuring device 10A described above, and thus redundant description thereof is omitted.

  Therefore, also in the second distance measuring device 10B, as in the first distance measuring device 10A, the distance calculation by the distance calculation unit 58 can be performed with high accuracy, and the calibration as described above is unnecessary. . In particular, in the second distance measuring device 10B, there is no need to provide a memory 80 or a memory area for storing the information table 78.

  It should be noted that the distance measuring device and the distance measuring method according to the present invention are not limited to the above-described embodiments, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

It is a block diagram which shows the structure of a 1st distance measuring device. It is explanatory drawing which shows schematic structure of an image pick-up element. 3A and 3B are explanatory diagrams showing a charge accumulation state in the image sensor. 4A and 4B are explanatory diagrams illustrating a charge transfer state in the image sensor. It is explanatory drawing which shows the principle which calculates | requires the phase delay of reflected light with the sampling value based on the imaging signal from an image sensor. It is explanatory drawing which shows the breakdown of an information table. It is a wave form diagram which shows the relationship between the modulated light and the exposure period before changing the period of an exposure period. It is a flowchart which shows the processing operation in the 1st ranging apparatus before changing the period of an exposure period. It is a wave form diagram which shows the relationship between the modulated light after changing the period of an exposure period, and an exposure period. It is a block diagram which shows the structure of a 2nd ranging device. It is explanatory drawing which shows the light wave ranging method of TOF (Time Of Flight) system. It is a wave form diagram which shows the delay of the phase of the reflected light with respect to modulated light. It is a flowchart which shows the processing operation in the distance measuring device which concerns on a prior art example. FIG. 14A is a waveform diagram showing the relationship among the modulated light, reflected light, synchronization signal, and exposure period in the first frame in the distance measuring apparatus according to the conventional example, and FIG. 14B is a waveform diagram showing the relationship in the third frame. 14C is a waveform diagram showing the relationship in the fifth frame, and FIG. 14D is a waveform diagram showing the relationship in the seventh frame.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10A, 10B ... 1st distance measuring device, 2nd distance measuring device 12 ... Modulated light 14 ... Light emission means 16 ... Detected object 18 ... Reflected light 20 ... Light receiving means 22 ... Calculation means 24 ... Synchronization signal generation part 26 ... Light emission part DESCRIPTION OF SYMBOLS 28 ... Light emission control part 30 ... Image pick-up element 32 ... Optical system 34 ... Image pick-up element control part 36 ... Analog signal processing part 38 ... A / D conversion part 40 ... Buffer memory 58 ... Distance calculating part 64 ... Exposure timing change part 66 ... Wavelength Change unit 68 ... Timing control unit 74 ... Light reception start change unit 76 ... Delay time correction unit 78 ... Information table 80 ... Memory 82 ... Wavelength calculation unit 84 ... First delay calculation unit 86 ... Second delay calculation unit 100 ... Exposure pulse generation Unit 102 ... Transfer pulse generation unit 104 ... Drive unit

Claims (12)

A light emitting means for emitting modulated light whose intensity is modulated at each of a plurality of light emission start timings;
A light receiving means for receiving reflected light from the object irradiated by the modulated light;
Anda calculating means for calculating a distance to the object based on the phase difference of the reflected light and the modulated light,
The modulated light is intensity-modulated at a constant frequency,
The light receiving means sets the time length from the light emission start timing to the light reception start time of the reflected light based on the number of times of the light emission start timing and the wavelength of the waveform of the modulated light intensity-modulated at the frequency. A ranging device that receives the reflected light from the object to be detected by changing ,
The light receiving means is
An imaging unit that samples the amount of the reflected light in an exposure period set at regular intervals with the light reception start time as a reference;
A timing control unit for changing a time length from the light emission start timing to the light reception start time of the reflected light based on the number of times of the light emission start timing and the wavelength in the modulated light; and
An exposure timing changing unit that changes the period of the exposure period based on a control signal from the outside,
The light emitting means includes a wavelength changing unit that changes the wavelength in the modulated light based on the period of the exposure period changed by the exposure timing changing unit,
The timing controller includes a number of the light emission start timing, based on the wavelength of the modified the modulated light, the distance measuring apparatus according to claim Rukoto varying the time length of up to the light detection start time. The distance measuring device according to claim 1 ,
A said wavelength in said modulated light corresponding to the changed cycle length of the exposure period, the memory information of the light detection start timing is registered table is stored,
Wherein the wavelength changing unit, based on the information of the table stored in the memory, to modify the wavelength of the modulated light,
The distance measuring device is characterized in that the timing control unit changes the time length until the light reception start time based on the number of times of the light emission start timing and the information of the table stored in the memory. The distance measuring device according to claim 2 , wherein
The distance measuring apparatus is characterized in that the table is accessed using an identification code corresponding to the changed period of the exposure period. The distance measuring device according to claim 1 ,
Based on the changed period of the exposure period, a wavelength calculation unit that calculates the wavelength in the modulated light;
Wherein the wavelength changing section may change the wavelength of the modulated light, to a wavelength obtained by the wavelength calculation unit,
The timing controller includes a number of the light emission start timing, based on the wavelength determined by the wavelength calculating unit, the distance measuring apparatus characterized by varying the time length of up to the light detection start time . The distance measuring device according to claim 1,
A distance measuring device that performs at least the following processing.
(1) The light emitting means emits first modulated light over a predetermined period based on the first light emission start timing, and emits second modulated light over a predetermined period based on the second light emission start timing,
(2) The light receiving means is a first reflected light from the detected object irradiated by the first modulated light from the first light reception start time based on the first light emission start timing over the predetermined period. And receiving the second reflected light from the detected object irradiated by the second modulated light over the predetermined period from the second light reception start time based on the second light emission start timing,
(3) The calculation means is configured to obtain the detection object based on at least a phase difference between the first modulated light and the first reflected light and a phase difference between the second modulated light and the second reflected light. Calculate the distance. The distance measuring device according to claim 5 , wherein
The light receiving means samples the light quantity of the first reflected light during an exposure period set for every predetermined period with the first light reception start time as a reference, and the constant with respect to the first light reception start time. Sampling the amount of the second reflected light in the exposure period set for each cycle;
The calculation means sets a value obtained by integrating the sampling results of the light quantity of the first reflected light over the predetermined period as a phase difference between the modulated light and the first reflected light, and the sampling result of the light quantity of the second reflected light A distance measuring apparatus characterized in that a value integrated over a predetermined period is used as a phase difference between the modulated light and the second reflected light. A light emission step of emitting modulated light whose intensity is modulated at each of a plurality of light emission start timings;
A light receiving step for receiving reflected light from the object irradiated by the modulated light;
Anda calculation step of calculating a distance to the object based on the phase difference of the reflected light and the modulated light,
The modulated light is intensity-modulated at a constant frequency,
In the light receiving step, the time length from the light emission start timing to the light reception start time of the reflected light is determined based on the number of times of the light emission start timing and the wavelength of the waveform in the modulated light intensity-modulated at the frequency. A ranging method for receiving the reflected light from the object to be detected by changing ,
The light receiving step includes
An imaging step of sampling the amount of the reflected light in an exposure period set at regular intervals with the light reception start time as a reference;
A timing control step of changing a time length from the light emission start timing to the light reception start time of the reflected light based on the number of times of the light emission start timing and the wavelength in the modulated light;
An exposure timing change step for changing the period of the exposure period based on a control signal from the outside,
The light emitting step has a wavelength changing step of changing the wavelength in the modulated light based on the period of the exposure period changed in the exposure timing changing step,
The timing control step is characterized in that the time length until the light reception start time is changed based on the number of times of the light emission start timing and the changed wavelength of the modulated light . The distance measuring method according to claim 7 ,
Using said wavelength in said modulated light corresponding to the changed cycle length of the exposure period, a table in which information of light detection start timing is registered,
Wherein the wavelength changing step, based on the information of the table, and change the wavelength of the modulated light,
The timing control step is characterized in that the time length until the light reception start time is changed based on the number of times of the light emission start timing and the information in the table. The distance measuring method according to claim 8 , wherein
The distance measuring method is characterized in that the access to the table is performed using an identification code corresponding to the changed period of the exposure period. The distance measuring method according to claim 7 ,
Based on the changed cycle length of the exposure period, it has a wavelength calculation step of calculating the wavelength in the modulated light,
In the wavelength changing step, the wavelength in the modulated light is changed to the wavelength obtained in the wavelength calculating step,
Wherein the timing control step, the distance measuring method of the number of times of the light emission start timing, based on the wavelength determined by the wavelength calculation step, and changing the time length of up to the light detection start time . The distance measuring method according to claim 7 ,
A distance measuring method characterized by performing at least the following processing.
(1) The light emitting step emits the first modulated light over a predetermined period based on the first light emission start timing, and emits the second modulated light over a predetermined period based on the second light emission start timing;
(2) In the light receiving step, the first reflected light from the detected object irradiated by the first modulated light from the first light receiving start time based on the first light emission start timing for the predetermined period. And receiving the second reflected light from the detected object irradiated by the second modulated light over the predetermined period from the second light reception start time based on the second light emission start timing,
(3) In the calculation step, based on at least the phase difference between the first modulated light and the first reflected light and the phase difference between the second modulated light and the second reflected light, Calculate the distance. The distance measuring method according to claim 11 ,
The light receiving step samples the light quantity of the first reflected light during an exposure period set for each predetermined period with the first light reception start time as a reference, and the constant with respect to the first light reception start time. Sampling the amount of the second reflected light in the exposure period set for each cycle;
The calculation step uses a value obtained by integrating the sampling results of the light quantity of the first reflected light over the predetermined period as a phase difference between the modulated light and the first reflected light, and uses the sampling result of the light quantity of the second reflected light as the phase difference. A distance measuring method characterized in that a value integrated over a predetermined period is used as a phase difference between the modulated light and the second reflected light.

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