JP5486150B2 - Ranging device, ranging method and ranging system - Google Patents

Description

  The present invention relates to a distance measuring device, a distance measuring method, and a distance measuring system. For example, reflected light from an object irradiated with emitted light is received for each pixel of an image sensor to obtain a three-dimensional structure of the object. The present invention relates to a distance measuring device, a distance measuring method, and a distance measuring system suitable for detection.

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

  As shown in FIG. 15, the apparatus according to this method includes, for example, an LED array, a light source 200 that emits intensity-modulated light (modulated light), and an object irradiated by the modulated light emitted from the light source 200. The imaging device 204 that receives the reflected light from 202 and an optical system 206 that forms an image of the reflected light on the imaging device 204 are included.

  When the modulated light emitted from the light source 200 to the object 202 is intensity-modulated at a high frequency of 20 MHz, for example, the wavelength is 15 m. Therefore, if the light travels a distance of 7.5 m, a phase delay of one cycle occurs. Will occur.

  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. 16, 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 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 object 202 can be detected by obtaining the phase delay φ according to the above equation for each pixel.

  For example, Patent Documents 1 and 2 have been proposed as distance measuring devices using the above-described principle.

  In the distance measuring apparatus according to Patent Document 1, the reflected light from an object is shifted in the exposure period of a plurality of patterns by shifting the phase of opening and closing of the charge sweep gate (overflow drain gate: OFDG) or the readout gate of the image sensor. The distance is measured by receiving the light.

  The distance measuring device according to Patent Document 2 is based on the same principle as that of Patent Document 1, but a grayscale image and a distance image can be obtained at substantially the same time.

  Further, Patent Document 3 irradiates an object with pulsed light and counts the number of clock pulses proportional to the time of flight (TOF) of the pulsed light, or alternately uses two charge accumulating units to charge. A technique for accumulating and obtaining a distance to an object from the ratio is disclosed.

Japanese Patent No. 3758618 JP 2006-46959 A Japanese translation of PCT publication No. 2003-510561

  However, Patent Document 3 described above does not have a function of removing an external light component, and there is a problem that accurate distance measurement cannot be performed under external light.

  The ranging methods of Patent Documents 1 and 2 can remove the external light component by using the modulated light as the irradiation light, but the modulation of the irradiation light is inaccurate (the sinusoidal modulation of the irradiation light). If the intensity change deviates from the sine curve), an error occurs in the distance measurement calculation. Therefore, precise modulation of the light source is necessary, but there is a problem that such control is difficult.

  The present invention has been made in consideration of such a problem. When measuring distance using pulsed light, an external light component can be removed, and measurement accuracy that can improve distance measurement accuracy. An object is to provide a distance measuring apparatus and a distance measuring method.

  In addition, the present invention can acquire a grayscale image of an object at the same time as a distance image obtained by distance measurement, and a 3D polygon image obtained from the distance data, or luminance data based on the grayscale image is mapped to the 3D polygon image. An object of the present invention is to provide a ranging system that can display a three-dimensional model image and can be applied to various applications.

A distance measuring device according to a first aspect of the present invention is a light emitting means for emitting pulsed light having a predetermined pulse width from a reference time, receives reflected light from an object irradiated by the pulsed light, and starts from the reference time. A first charge amount accumulated in a first interval over a period corresponding to the pulse width; a second charge amount accumulated in a second interval over a period corresponding to the pulse width from the time when the first interval has elapsed; A light receiving means for obtaining a third charge amount accumulated in a third interval over a period corresponding to the pulse width from the time point of the passage of the interval; the first charge amount, the second charge amount and the second charge amount obtained by the light receiving means; A calculation unit that calculates a distance to the object based on three charge amounts, and the calculation unit includes a comparison unit that compares the first charge amount, the second charge amount, and the third charge amount; , 1st variable, 2nd variable and 3rd variable Accordingly, a distance calculation unit that calculates a distance based on the first section or the second section, and the first variable according to a section with the least amount of charge among the first section and the third section, A selection unit that selects a correspondence relationship between the second variable and the third variable and the first charge amount, the second charge amount, and the third charge amount; and an addition unit; and the distance calculation When the setting distance determined by the pulse width is L, the first variable is Xa, the second variable is Xb, and the third variable is Xc, {(Xb−Xc) / (Xa + Xb−Xc × 2 )} × L is calculated to obtain the distance, and when the section with the smallest amount of charge is the third section, the selection unit sets the first variable Xa to the first charge amount and the second variable Xb. Are selected as the second charge amount and the third variable Xc as the third charge amount. When the section is the first section, the second charge amount is selected as the first variable Xa, the third charge amount is selected as the second variable Xb, and the first charge amount is selected as the third variable Xc, The adding unit adds 0 to the distance obtained by the distance calculation unit when the section with the smallest charge amount is the third section, and when the section with the least charge amount is the first section, The set distance L is added to the distance obtained by the distance calculation unit.
In this case, when the section with the smallest amount of charge is the second section, a measurement error may be set.
Further, the distance measuring device according to the second aspect of the present invention includes a light emitting unit that emits pulsed light having a predetermined pulse width from a reference time, reflected light from an object irradiated with the pulsed light, and an external light component. Light receiving means for receiving the received light in n sections arranged in order for each period corresponding to the pulse width from the reference time to obtain n received integrated intensity, and the n received integrated intensity comparing, and two light receiving integrated intensity greater intensity (first light receiving integrated intensity and the second light receiving integrated intensity), a small strength (n-2) number of detects the received light integrated intensity, the n intervals Of these, the reflected light arrives and the external light component enters the two sections (first section and second section) corresponding to the first received light integrated intensity and the second received light integrated intensity. The light section and the other (n-2) sections are Comparing means only component is an outer light interval incident, intensity-small and (n-2) pieces each reference intensity light receiving integrated intensity of in the external light section, (n-2) times the change in the number of reference intensity A function of obtaining a reference intensity distribution in n sections including the reflected light section and the outside light section, and the first section in the reflected light section from the obtained reference intensity distribution. and means for determining a first reference intensity and the second reference intensity corresponding to the second period, the first reference intensity corresponding respectively from the first light receiving integrated intensity and the second light receiving integrated intensity of said reflected light section and It means for obtaining a first correction integrated intensity and the second correction integrated intensity by subtracting the second reference strength, based on the first correction integrated intensity and the second correction integrated intensity, and calculates the distance to the object Means And, means for calculating a distance to the object, wherein the set distance determined by the pulse width L, the first correction integrated intensity d1, the second correction integrated intensity d2, among the n intervals, the When the number of sections from the reference time until the reflected light section arrives is m,
{D2 / (d1 + d2)} × L + m × L
To calculate the distance k to the object .

  Thereby, when ranging using pulsed light, external light components can be removed, and the accuracy of ranging can be improved.

  In these configurations, the comparison unit, the distance calculation unit, the selection unit, etc. that constitute the calculation means can be configured as a single block as hardware, thereby simplifying the software and speeding up the calculation process. Can do.

Next, a distance measuring method according to a third aspect of the present invention includes a light emitting step of emitting pulsed light having a predetermined pulse width from a reference time, and reflected light from an object irradiated by the pulsed light from the reference time. a first light receiving step Ru obtain a first light receiving integrated intensity received by the first section over a period of time corresponding to the pulse width, the second over a period of time corresponding to said reflected light from said first interval elapsed time to the pulse width the third light receiving integrated intensity by receiving a second light receiving integrated intensity by receiving a second light receiving step Ru obtained, in the third section over a period corresponding to the pulse width of the reflected light from said second interval elapsed time in the interval and a third light receiving step Ru obtained, the first light receiving integrated intensity, based on the second light receiving integrated intensity and the third light receiving integrated intensity, and a calculation step of calculating a distance to the object, the arithmetic Step before Based on the first variable, the second variable, and the third variable, the comparison step of comparing the first received light integrated intensity, the second received light integrated intensity, and the third received light integrated intensity, and the first interval or the second interval A distance calculation step for calculating a distance based on the first variable, the second variable, and the third variable according to a section having the smallest received light integration intensity among the first section and the third section, A selection step for selecting a correspondence relationship between the first received light integrated intensity, the second received light integrated intensity, and the third received light integrated intensity, and an adding step, and the distance calculating step is determined by the pulse width. When the set distance is L, the first variable is Xa, the second variable is Xb, and the third variable is Xc, {(Xb−Xc) / (Xa + Xb−Xc × 2)} × L is calculated. Determining the distance and selecting the step When the interval with the smallest received light integration intensity is the third interval, the first received light integrated intensity is set as the first variable Xa, the second received light integrated intensity is set as the second variable Xb, and the third variable Xc is set as the value. When the third received light integrated intensity is selected, and the section with the smallest received light integrated intensity is the first section, the second received light integrated intensity is set to the first variable Xa, and the third received light integrated intensity is set to the second variable Xb. The first received light integrated intensity is selected as the third variable Xc, and the adding step sets the distance obtained in the distance calculating step to 0 when the section having the smallest received light integrated intensity is the third section. And the set distance L is added to the distance obtained in the distance calculating step when the section with the smallest received light integration intensity is the first section .

  Thereby, when ranging using pulsed light, external light components can be removed, and the accuracy of ranging can be improved.

  In the second aspect of the present invention, when the received light integrated intensity received in the second light receiving step is regarded as the reference intensity, a measurement error may be set.

Next, a distance measuring method according to a fourth aspect of the present invention includes a light emitting step of emitting pulsed light having a predetermined pulse width from a reference time, reflected light from an object irradiated with the pulsed light, and an external light component. a light receiving step of obtaining the n-number of light-receiving integrated intensity light, each received at the pulse width of n which are arranged in order for each period corresponding to the interval from the reference time including, said n receiving light The integrated intensities are compared, and two received light integrated intensities (first received light integrated intensity and second received light integrated intensity) having a high intensity and (n−2) received light integrated intensities having a low intensity are detected , and the n light receiving integrated intensities are detected. The reflected light arrives and the outside light component is incident on two sections (first section and second section) corresponding to the first received integrated intensity and the second received integrated intensity. And the other (n-2) sections are the reflected light sections A comparison step and a small strength in the external light period (n-2) pieces each reference intensity light receiving integrated intensity of only the external light component is to incident external light section, (n-2) pieces of reference intensity obtaining a distribution of the reference intensity at the n sections, including the time change in the function of said reflected light period and the external light section, the distribution of the resulting said reference intensity, said in the reflected light section A step of obtaining a first reference intensity and a second reference intensity corresponding to the first section and the second section, and the first corresponding to the first received light integrated intensity and the second received light integrated intensity in the reflected light section, respectively . obtaining a first correction integrated intensity and the second correction integrated intensity by subtracting the reference intensity and the second reference strength, based on the first correction integrated intensity and the second correction integrated intensity, until the object And a step of calculating the distance, the step of calculating the distance to said object, said set distance determined by the pulse width L, and the first correction integrated intensity d1, the second correction integrated intensity d2, the Among the n sections, when the number of sections from the reference time to the arrival of the reflected light section is m,
{D2 / (d1 + d2)} × L + m × L
To calculate the distance k to the object .

  When ranging using pulsed light, an external light component that changes with time can be removed, and the accuracy of distance measurement can be further improved.

In the fourth aspect of the present invention, when the first section and the second section are not continuous in time, a ranging error may be generated.

In the fourth aspect of the present invention, the comparison step obtains a difference in received light integrated intensity for each section , determines a section where the difference is greater than 0 and maximum as a start section of the reflected light section, and the difference is the smaller the absolute value is maximum interval than 0, it may be determined that the exit section of the reflected light section. In this case, it is possible to reliably detect the section in which the reflected light has arrived.

Next, a distance measuring system according to a fifth aspect of the present invention is a distance for obtaining a distance image by calculating a distance corresponding to the distance measuring device according to the first aspect of the present invention and each light receiving unit in the distance measuring apparatus. An image acquisition unit; and a grayscale image acquisition unit that obtains a grayscale image corresponding to each light receiving unit based on a charge amount of the section with the smallest charge amount detected corresponding to each light receiving unit in the distance measuring device. It is characterized by having.

  As a result, a grayscale image of an object can be obtained simultaneously with a distance image obtained by ranging, and a 3D polygon image obtained from distance data, or a 3D model in which luminance data from the grayscale image is mapped to the 3D polygon image Images can be displayed and can be applied to various applications.

In the fifth aspect of the present invention, an image recording unit that records the distance image and the grayscale image in association with each other may be provided.

In the fifth aspect of the present invention, distance data corresponding to each light receiving unit in the distance image and density data corresponding to each light receiving unit in the gray image are recorded on a recording medium in association with each light receiving unit. You may make it have a data recording means.

  As described above, according to the distance measuring device and the distance measuring method according to the present invention, it is possible to remove the external light component and improve the distance measurement accuracy when the distance is measured using the pulsed light. be able to.

  Further, according to the distance measuring system according to the present invention, it is possible to acquire a grayscale image of an object at the same time as a distance image obtained by distance measurement, and a 3D polygon image obtained from distance data, or a grayscale image on the 3D polygon image. It is possible to display a three-dimensional model image obtained by mapping luminance data based on an image, and it can be applied to various applications.

  Hereinafter, embodiments of a distance measuring device, a distance measuring method, and a distance measuring system according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a distance measuring system 10 according to the present embodiment includes a casing 12 having a substantially rectangular parallelepiped or cubic shape, and a pulse provided in the casing 12 and having a predetermined pulse width from a reference time. Light emitting means 14 (see FIG. 2) for emitting light, light receiving means 16 (see FIG. 2) for receiving reflected light from an object irradiated with pulsed light, and an object based on data obtained by the light receiving means 16 And calculating means 18 (see FIG. 2) for calculating the distance up to.

  An irradiation light source 20 and a photographing optical lens 22 are provided on the front surface 12 a of the housing 12. The optical lens 22 is provided substantially at the center of the front surface 12 a of the housing 12, and the irradiation light source 20 has a number of infrared LEDs 24 arranged around the optical lens 22 in the front surface 12 a of the housing 12.

  As schematically shown in FIG. 2, inside the housing 12, a CPU 26 and light emission controlled by the CPU 26 so as to emit pulsed light 28 having a predetermined pulse width from each infrared LED 24. A control unit 30, an image sensor 32, an optical system 36 (including the optical lens 22) that forms an image of reflected light 34 on the light receiving surface of the image sensor 32, an image sensor control unit 38 for driving the image sensor 32, The analog signal processing unit 40 that processes the imaging signal Sb from the imaging element 32 into an analog image signal Sc, the A / D conversion unit 42 that converts the image signal Sc into image data Dc, and the image data Dc Are stored in the buffer memory 44 and the image data Dc stored in the buffer memory 44 is subjected to data shaping and format conversion (YC image data (Y: luminance signal, : And a data processing circuit 46 which performs like) to convert to the color difference signals).

  Inside the housing 12, the storage unit 50 for recording the image data Dc stored in the buffer memory 44 or the image data Dc after the format conversion in the storage device 48, and the image data Dc are stored in the two-dimensional image. Display unit 56 for displaying on the first display 52 or displaying on the second display 54 as a three-dimensional image, various parameters in the distance measuring system 10, the image data Dc, and the like via the communication port 58. And a communication unit 60 for receiving various data from the outside.

  An operation panel 62 is installed on the outer surface of the housing 12. The operation panel 62 includes at least a liquid crystal display unit 64 for operation guidance, an operation unit 66 for controlling the optical system 36, and various switches 68 such as a mode dial, a cross key, and a power switch. The liquid crystal display unit 64, operation unit 66, various switches 68 and signals exchanged with the CPU 26 are performed via an input / output interface 70 (I / F).

  The light emitting unit 14 includes the above-described light emission control unit 30 and the irradiation light source 20 (multiple infrared LEDs 24), and the light receiving unit 16 includes the above-described imaging element 32, optical system 36, and imaging element control. Unit 38, analog signal processing unit 40, A / D conversion unit 42, and buffer memory 44.

  The light emitting means 14 is configured to emit pulsed light 28 whose pulse width W is set to a predetermined period from the reference time t0 as shown in FIG. 3, for example, under the control of the light emission control unit 30. The predetermined period is set based on the maximum measurable distance L set by the user. For example, when it is assumed that an object is present at a point of the maximum distance L, the pulsed light 28 is emitted to irradiate the object, and the light travels by a distance 2L before the reflected light 34 returns. Therefore, the time from when the pulsed light 28 is emitted until the reflected light 34 returns is 2 L / c (sec), where c (m / sec) is the speed of light. By assigning this time to the pulse width W of the pulsed light 28, the distance of the object existing up to the maximum distance L can be measured. The reference time t0 described above can be set at the time when the user operates a switch 68 (for example, a distance measurement start switch) on the operation panel 62.

  On the other hand, as shown in FIG. 4, the image sensor 32 of the light receiving means 16 has a large number of light receiving portions 72 arranged in a matrix, for example. The light receiving unit 72 includes a photoelectric conversion unit 74 (photodiode) that performs photoelectric conversion into an amount of charge corresponding to the amount of incident light, and two storage units (a first storage unit 76a and a first storage unit 76a) that are arranged corresponding to the photoelectric conversion unit 74. 2 storage unit 76b). In the imaging device 32, a large number of first vertical transfer paths 78a that are common to a large number of first storage units 76a arranged in the column direction are arranged in the row direction and arranged in the column direction. A large number of second vertical transfer paths 78b common to a large number of second storage units 76b are arranged in the row direction. An output unit 80 is disposed at the final stage of each first vertical transfer path 78a and each second vertical transfer path 78b, and the charges transferred through the first vertical transfer path 78a and the second vertical transfer path 78b are output from these output sections. 80 are converted into voltage signals and output. The voltage-converted charges are swept out to the drain regions as the reset signal is applied.

  Further, as shown in FIG. 5, the light receiving portion is provided with an opening 82 corresponding to the central portion of each photoelectric conversion portion 74, and a light shielding film 84 is formed in the other portions so that light does not enter. ing. A central electrode 86 made of, for example, a transparent electrode is formed on the photoelectric conversion unit 74 corresponding to the opening 82, a first storage electrode 88a is formed on the first storage unit 76a, and a second electrode on the second storage unit 76b. The second storage electrode 88b is formed, and the first adjustment electrode 90a and the second adjustment electrode 90a for tilting the potential of the photoelectric conversion unit 74 between the central electrode 86 and the first storage electrode 88a and between the central electrode 86 and the second storage electrode 88b. An adjustment electrode 90b is formed. Further, a first transfer electrode 92a is formed between the first storage unit 76a and the first vertical transfer path 78a to transfer the charge stored in the first storage unit 76a to the first vertical transfer path 78a. ing. Similarly, a second transfer electrode 92b is formed between the second storage unit 76b and the second vertical transfer path 78b to transfer the charges stored in the second storage unit 76b to the second vertical transfer path 78b. Has been.

  For the electrode groups formed on the first vertical transfer path 78a and the second vertical transfer path 78b, for example, a configuration similar to that of an interline CCD image sensor can be adopted. Omitted.

  Here, the operation of one light receiving unit 72 will be described. First, as shown by a solid line A in FIG. 5, the voltages of the central electrode 86, the first adjustment electrode 90a, and the second adjustment electrode 90b are adjusted, and the potential of the photoelectric conversion unit 74 is directed toward the first accumulation unit 76a. Make the slope down. Then, when light enters the light receiving unit 72, an amount of charge corresponding to the amount of incident light is generated in the photoelectric conversion unit 74, and the generated charge is first accumulated along the potential gradient in the photoelectric conversion unit 74. The data is transferred and accumulated in the unit 76a (accumulation operation).

  When a certain period of time has elapsed, the voltages of the central electrode 86, the first adjustment electrode 90a, and the second adjustment electrode 90b are adjusted, and the potential of the photoelectric conversion unit 74 is now directed toward the second storage unit 76b. Make the slope down. Accordingly, an amount of charge corresponding to the amount of incident light is generated in the photoelectric conversion unit 74, and the generated charge is transferred and accumulated in the second accumulation unit 76b along the potential gradient in the photoelectric conversion unit 74 (accumulation operation). ). During the period of charge transfer and accumulation to the second accumulation unit 76b, the voltage applied to the first transfer electrode 92a is adjusted to lower the potential barrier 94a between the first accumulation unit 76a and the first vertical transfer path 78a. Then, the charge in the first storage unit 76a is transferred to the first vertical transfer path 78a (read operation).

  When a certain period of time has elapsed, the voltages of the central electrode 86, the first adjustment electrode 90a, and the second adjustment electrode 90b are adjusted, and the potential of the photoelectric conversion unit 74 is inclined downward again toward the first storage unit. Let me. As a result, a charge corresponding to the amount of incident light is generated in the photoelectric conversion unit 74, and the generated charge is transferred and accumulated in the first accumulation unit 76a along the potential gradient in the photoelectric conversion unit (accumulation operation). . During the period of charge transfer and accumulation to the first accumulation unit 76a, the voltage applied to the second transfer electrode 92b is adjusted to lower the potential barrier 94b between the second accumulation unit 76b and the second vertical transfer path 78b. Then, the charge in the second accumulation unit 76b is transferred to the second vertical transfer path 78b (reading operation). During the read operation, the charges in the first vertical transfer path 78a are sequentially transferred to the output unit 80, and a voltage signal is output from the output unit 80. The charges converted into the voltage signal are sequentially swept out to the drain region. Will be reset (reset operation). These operations are sequentially repeated.

  Next, the operation of the image sensor 32 corresponding to the distance measuring system 10 will be described with reference to FIG.

  First, in the first section T1 extending from the reference time t0 to a period corresponding to the pulse width W, each photoelectric conversion unit 74 generates a charge corresponding to the amount of incident light and accumulates it in the first accumulation unit 76a (accumulation operation). ).

  In the second section T2 that extends from the time point of the first section T1 to the period corresponding to the pulse width W, the stored charge in the first storage section 76a is read out to the first vertical transfer path 78a (read operation). In the second section T2, each photoelectric conversion unit 74 generates a charge corresponding to the amount of incident light, and this time accumulates in the second accumulation unit 76b (accumulation operation).

  In the third section T3 that extends from the time point of the second section T2 to the period corresponding to the pulse width W, the stored charge in the second storage section 76b is read to the second vertical transfer path 78b (reading operation). Further, in the third section T3, each photoelectric conversion unit 74 generates a charge corresponding to the amount of incident light and accumulates it again in the first accumulation unit 76a (accumulation operation). Further, in the third section T3, the charges read out to the first vertical transfer path 78a are transferred to the output unit 80, and converted into voltage signals corresponding to the charge amounts in the output unit 80, respectively. The charge converted into the voltage signal is reset (reset operation). The voltage signal output from the output unit 80 of the plurality of first vertical transfer paths 78a is converted as the imaging signal Sb of the first section T1 in each light receiving unit 72 by the analog processing circuit 40 in the subsequent stage. The imaging signal Sc in the first section T1 is converted into a digital signal by the A / D converter 42 and image data in the first section T1 (data in which imaging data Dc corresponding to each light receiving section 72 is arranged: first It is recorded in the buffer memory 44 as image data Dc1).

  In a fourth section T4 that extends from the time point of the third section T3 to a period corresponding to the pulse width W, the stored charge in the first storage section 76a is read out to the first vertical transfer path 78a (reading operation). In the fourth section T4, the charges read to the second vertical transfer path 78b are transferred to the output unit 80, and converted into voltage signals corresponding to the charge amounts in the output unit 80, respectively. The charge converted into the voltage signal is reset (reset operation). The voltage signals output from the output units 80 of the plurality of second vertical transfer paths 78b are subjected to the same processing as described above, and are recorded in the buffer memory 44 as image data (second image data Dc2) in the second section T2. Is done.

  Then, in the fifth section T5 extending from the time point of the fourth section T4 to the period corresponding to the pulse width W, the charge read to the first vertical transfer path 78a is transferred to the output section 80, and the output section In 80, each is converted into a voltage signal corresponding to the amount of charge, and the charge converted into a voltage signal is reset (reset operation). The voltage signals output from the output units 80 of the plurality of first vertical transfer paths 78a are subjected to the same processing as described above, and are recorded in the memory buffer 44 as image data (third image data Dc3) in the third section T3. Is done.

  On the other hand, as shown in FIG. 2, the calculation unit 18 includes a distance calculation unit 96 that calculates a distance to an object corresponding to each light receiving unit 72 based on the first image data Dc1 to the third image data Dc3.

  A calculation algorithm in the distance calculation unit 96, in particular, a distance calculation method (first calculation method) in one light receiving unit 72 will be described with reference to FIGS.

  First, the case where external light is not considered will be described with reference to FIG.

  Pulse light 28 having a pulse width W (= 2L / c) is emitted from the reference time t0, and reflected light 34 from the object irradiated by the pulse light 28 arrives between the first section T1 and the second section T2. Assuming that Note that L represents the set maximum distance as described above.

In this case, if the reflected light intensity is I, the photoelectric conversion efficiency in the photoelectric conversion unit 74 is ε, and the distance to the object is k, the first accumulated in the first interval T1, the second interval T2, and the third interval T3. The one charge amount d1 (light reception integral intensity), the second charge amount d2 (light reception integral intensity), and the third charge amount d3 (light reception integral intensity) have the following relationship.
d1 = εI (2L / c-2k / c)
d2 = εI (2 k / c)
d3 = 0
At this time, the distance k to the object is obtained by the following arithmetic expression.
Distance k = {d2 / (d1 + d2)} × L
= {(2k / c) / (2L / c)} * L
= (2k / c) / (2 / c)
= K

  Next, a case where external light is taken into account will be described with reference to FIG. At this time, the reflected light intensity when there is no external light component is I, and the external light component is Io.

When there is an external light component Io, the accumulated charge and the distance k obtained by calculation can be rewritten as follows.
d1 ′ = ε {I (2L / c−2k / c) + Io (2L / c)}
d2 ′ = ε {I (2k / c) + Io (2L / c)}
d3 ′ = ε {Io (2L / c)}
Distance k = {d2 ′ / (d1 ′ + d2 ′)} × L
= {K + L (Io / I)} / {1 + 2 (Io / I)}

  This is because as the outside light intensity Io is larger than the reflected light intensity I, the difference between the distance k obtained by calculation and the actually measured distance k increases. When Io >> I, the distance k obtained by calculation. Becomes L / 2.

In order to prevent this, the third charge amount d3 (light reception integrated intensity) in the third section T3 that does not receive the reflected light component is used. Specifically, the following relational expression is used.
d1 '= d1-d3
d2 '= d2-d3
Distance k = {d2 ′ / (d1 ′ + d2 ′)} × L (1)

The above calculation method assumes that the reflected light 34 arrives between the first interval T1 and the second interval T2, but the reflected light 34 arrives between the second interval T1 and the third interval T3. In this case, the distance k can be obtained by the same method. In this case, since only the outside light component Io exists in the first section T1, and it is necessary to add the distance L corresponding to the first section T1, it can be obtained by the following arithmetic expression.
d2 '= d2-d1
d3 '= d3-d1
Distance k = {d3 ′ / (d2 ′ + d3 ′)} × L + L (2)

  A processing method in the calculation means using the above calculation method will be described with reference to the flowchart of FIG.

  First, in step S1 of FIG. 8, the initial value 1 is stored in the counter n for specifying the light receiving unit 72.

  Thereafter, in step S2, data indicating the first charge amount d1 to the third charge amount d3 corresponding to the nth light receiving unit 72 is taken from the buffer memory 44.

  Thereafter, in step S3, the lowest charge amount is searched from the taken first charge amount d1 to third charge amount d3. That is, a section having only an external light component is searched for from the first section T1 to the third section T3.

In step S4, it is determined whether or not the minimum charge amount is the third charge amount d3. If the lowest charge amount is the third charge amount d3, the process proceeds to the next step S5, where the third section T3 is recognized as a section of only the external light component, and the charge amount in the other section, that is, the first charge amount d1. The second charge amount d2 is corrected as follows.
d1 '= d1-d3
d2 '= d2-d3

Thereafter, in step S6, the distance k to the object in the light receiving unit 72 is calculated by the following equation.
Distance k = {d2 ′ / (d1 ′ + d2 ′)} × L

On the other hand, if it is determined in step S4 that the minimum charge amount is not the third charge amount d3, the process proceeds to step S7, and it is determined whether or not the minimum charge amount is the first charge amount d1. . If the lowest charge amount is the first charge amount d1, the process proceeds to the next step S8, where the first section T1 is recognized as the section of only the external light component, and the charge amount in the other section, that is, the second charge amount d2. The third charge amount d3 is corrected as follows.
d2 '= d2-d2
d3 '= d3-d2

Thereafter, in step S9, the distance k to the object in the light receiving unit 72 is calculated by the following equation.
Distance k = {d3 ′ / (d2 ′ + d3 ′)} × L + L

  If it is determined in step S7 that the minimum charge amount is not the first charge amount d1, the process proceeds to step S10, and the distance calculation is determined to be an error. Specifically, the distance k is set to “−1” indicating an error, for example.

  In the stage where the process in step S6, step S9 or step S10 described above is omitted, the process proceeds to step S11, and the value of the distance k and the value of the minimum charge amount are output.

  The output value of the distance k is recorded at an address corresponding to the nth light receiving unit 72 in the first recording area for creating the distance image in the buffer memory 44. The output value of the lowest charge amount is recorded at an address corresponding to the nth light receiving portion 72 in the second recording area for creating a grayscale image in the buffer memory 44.

  In the next step S12, the value of the counter n is updated by +1. Thereafter, in step S13, it is determined whether or not processing has been performed for all the light receiving units 72. This determination is made based on whether or not the value of the counter n exceeds the total number of light receiving units 72.

  If the processing has not been completed for all the light receiving units 72, the process returns to step S2 to search for the minimum charge amount for the next light receiving unit 72, calculate the distance to the object, and calculate these values in the first recording area. And stored in the second recording area.

  Then, in step S13, when it is determined that the processing has been completed for all the light receiving units 72, the calculation processing ends.

  As described above, the distance measuring system 10 emits the pulsed light 28 having the predetermined pulse width W from the reference time t0 and receives the reflected light 34 from the object irradiated with the pulsed light 28, thereby the first section. The first charge amount d1 accumulated in T1, the second charge amount d2 accumulated in the second interval T2, and the third charge amount d3 accumulated in the third interval T3 are acquired, and further, the first charge amount d1 Since the distance k to the object is calculated after subtracting the charge amount (minimum charge amount) of the section with the smallest charge amount from the third charge amount d3, the distance is measured using the pulsed light 28. In this case, the external light component can be removed and the accuracy of distance measurement can be improved.

  In addition, a distance image corresponding to the entire light receiving unit 72 is obtained by obtaining the distance for each light receiving unit 72, and a grayscale image corresponding to the entire light receiving unit 72 is obtained based on the minimum amount of charge acquired for each light receiving unit 72. Therefore, it is possible to display a three-dimensional polygon image obtained from distance data and a three-dimensional model image obtained by mapping luminance data based on a grayscale image on the three-dimensional polygon image, and can be applied to various applications. .

  In the above example, the configuration of the calculation means 18, particularly the distance calculation unit 96 is shown by an algorithm. However, like the distance measurement calculation circuit 98 shown in FIG. May be.

  As shown in FIG. 9, the distance calculation circuit 98 includes a data read circuit unit 100, an outside light section determination circuit unit 102, a distance calculation circuit unit 104, an offset amount determination circuit unit 106, and an offset amount addition. Circuit portion 108.

  The data reading circuit unit 100 sequentially reads the first charge amount d1 corresponding to each light receiving unit 72 from the first image data Dc1 of the buffer memory 44, and the second image data of the buffer memory 44. A second readout circuit 110b that sequentially reads the value of the second charge amount d2 corresponding to each light receiving unit 72 from Dc2, and the third charge amount d3 corresponding to each light receiving unit 72 from the third image data Dc3 of the buffer memory 44. A third readout circuit 110c for reading out the values in order;

  The external light section determination circuit unit 102 includes a comparison circuit unit 112 and an external light section instruction unit 114.

  The comparison circuit unit 112 compares the first charge amount d1 from the first readout circuit 110a with the second charge amount d2 from the second readout circuit 110b, and when the first charge amount d1 ≧ the second charge amount d2. A first comparator 116a that outputs a high level signal (logic “1”) and a low level signal (logic “0”) otherwise, and a second charge amount d2 from the second readout circuit 110b, Compared with the third charge amount d3 from the third readout circuit 110c, a high level signal (logic “1”) is output when the second charge amount d2> the third charge amount d3, and low otherwise. The second comparator 116b that outputs the level signal (logic “0”), the third charge amount d3 from the third read circuit 110c and the first charge amount d1 from the first read circuit 110a are compared, When 3 charge amount d3> first charge amount d1, a high level signal (logic “1”) is output. And force, and a third comparator 116c for outputting the other low-level signal when the (logic "0").

  The outside light section instructing unit 114 outputs a logical product of the inversion of the output of the first comparator 116a and the output of the third comparator 116c, the inversion of the output of the third comparator 116c, and the second And a second AND circuit 118b that outputs a logical product with the output of the comparator 116b.

  That is, when the first section T1 is only the external light component, the output of the third comparator 116c is at a high level and the output of the first comparator 116a is at a low level, so the output of the first AND circuit 118a is at a high level. This indicates that the outside light section is the first section T1. Further, when the third section T3 is only the external light component, the output of the second comparator 116b is at a high level and the output of the third comparator 116c is at a low level, so that the output of the second AND circuit 118b is at a high level. This indicates that the outside light section is the third section T3.

  The ranging calculation circuit unit 104 includes a first selection circuit 120a, a second selection circuit 120b, a third selection circuit 120c, and an arithmetic circuit 122 that performs the calculation of the above-described equation (1).

  Each of the first selection circuit 120a to the third selection circuit 120c has five input terminals (first terminal φ1 to fifth terminal φ5) and one output terminal φ0, and the first readout circuit is connected to each first terminal φ1. The output of the second readout circuit 110b is connected to each second terminal φ2, and the output of the third readout circuit 110c is connected to each third terminal φ3.

  The output of the first AND circuit 118a is connected to the fifth terminal φ5 of the first selection circuit 120a, the fifth terminal φ5 of the second selection circuit 120b, and the fourth terminal φ4 of the third selection circuit 120c, respectively. The output of the second AND circuit 118b is connected to the fourth terminal φ4 of the circuit 120a, the fourth terminal φ4 of the second selection circuit 120b, and the fifth terminal φ5 of the third selection circuit 120c.

  When a high level signal is input to the fourth terminal φ4, the first selection circuit 120a selects the first charge amount d1 input to the first terminal φ1 and outputs the first charge amount d1 through the output terminal φ0. When a high level signal is input to the terminal φ5, the second charge amount d2 input to the second terminal φ2 is selected and output.

  The second selection circuit 120b selects and outputs the second charge amount d2 when a high level signal is input to the fourth terminal φ4, and receives the third charge when the high level signal is input to the fifth terminal φ5. The quantity d3 is output.

  The third selection circuit 120c selects and outputs the first charge amount d1 when a high level signal is input to the fourth terminal φ4, and the third charge 120c when the high level signal is input to the fifth terminal φ5. The quantity d3 is output.

  On the other hand, the arithmetic circuit 122 has a first input terminal φa to which the output of the first selection circuit 120a is input, a second input terminal φb to which the output of the second selection circuit 120b is input, and an output of the third selection circuit 120c. Has a third input terminal φc and one output terminal φ0.

When the value input to the first input terminal φa is Xa, the value input to the second input terminal φb is Xb, and the value input to the third input terminal φc is Xc, the arithmetic circuit 122 An arithmetic expression is calculated, and the calculation result is output from the output terminal φ0.
{(Xb−Xc) / (Xa + Xb−Xc × 2)} × L

  Next, the offset amount determination circuit unit 106 includes a first register 124a storing a first constant (= 0), a second register 124b storing a second constant (= L), and a selection circuit 126. Have.

  The selection circuit 126 has four input terminals (first terminal φ1 to fourth terminal φ4) and one output terminal φ0. The output of the first register 124a is connected to the first terminal φ1, and the second terminal φ2 is connected. The output of the second register 124b is connected to the third terminal φ3, the output of the second AND circuit 118b is connected to the third terminal φ3, and the output of the first AND circuit 118a is connected to the fourth terminal φ4.

  When a high level signal is input to the third terminal φ3, the value (first constant = 0) of the first register 124a input to the first terminal φ1 is output, and the high level signal is output to the fourth terminal φ4. Is inputted, the value (second constant = L) of the second register 124b inputted to the second terminal φ2 is outputted.

  The offset amount addition circuit unit 108 includes an addition circuit 128. The adder circuit 128 has two input terminals (first input terminal φ1 and second input terminal φ2) and one output terminal φ0, and the value input to the first input terminal φ1 and the second input terminal φ2. Is added to the input value, and the added value is output via the output terminal φ0.

  The output of the arithmetic circuit 122 is connected to the first input terminal φ1, and the output of the selection circuit 126 is connected to the second input terminal φ2.

  Accordingly, when the output of the first AND circuit 118a is at a high level (external light section is the first section T1), the distance calculation calculation circuit 98 has the second charge amount d2 and the second charge amount d2 at the first input terminal φa of the calculation circuit 122. Since the third charge amount d3 is input to the input terminal φb and the first charge amount d1 is input to the third input terminal φc, the above equation (2) is calculated and the result is output from the adder circuit 128. Become.

  Similarly, when the output of the second AND circuit 118b is at a high level (the external light interval is the third interval T3), the first charge amount d1 is applied to the first input terminal φa, the second charge amount d2 is applied to the second input terminal φ2, and the second charge amount d2 is output. Since the third charge amount d3 is input to the three input terminal φ3, the above-described equation (1) is calculated and the result is output from the adder circuit 128.

  If this distance calculation circuit 98 is used, the data read circuit unit 100, the outside light section determination circuit unit 102, the distance calculation circuit unit 104, the offset amount determination circuit unit 106, and the offset amount constituting the calculation means 18 are used. The adder circuit unit 108 can be configured as a single block as hardware, so that the software of the distance measuring system 10 can be simplified and the speed of arithmetic processing can be increased.

  Next, another calculation method (second calculation method) of the calculation unit 18 in the distance measuring system 10 will be described with reference to FIGS. 10A to 11.

  The second calculation method uses the same method as the first calculation method described above, but performs a series of operations shown in FIG. 3 for the number of cycles set in advance to acquire a temporally changing external light component. The difference is that the reflected light intensity is detected more accurately.

  In this second calculation method, when the number of cycles is N, the storage capacity of the buffer memory 44 is set to a capacity that can record 3N pieces of image data. In order to simplify the explanation, the number of cycles N is assumed to be 3.

  The first charge amount d1 accumulated in each first section T1 of the first cycle C1 to the third cycle C3 is stored in the buffer memory 44 as corresponding first image data Dc1, fourth image data Dc4, and seventh image data Dc7. To do.

  Further, the buffer memory 44 stores the second charge amount d2 accumulated in each second section T2 of the first cycle C1 to the third cycle C3 as the corresponding second image data Dc2, fifth image data Dc5, and eighth image data Dc8. To remember.

  Similarly, the third charge amount d3 accumulated in each of the third sections T3 of the first cycle C1 to the third cycle C3 is buffered as corresponding third image data Dc3, sixth image data Dc6, and ninth image data Dc9. 44.

  The processing related to one light receiving unit 72 will be mainly described. First, it is assumed that the distance to the object is farther than 3L, but is closer than 4L, and the outside light is gradually becoming brighter. As shown in FIG. 10A, the change in the amount of charge at one imaged light receiving unit 72 is such that the reflected light 34 arrives between the fourth section T4 and the fifth section T6, and the other sections are only the external light component. In addition, it is possible to obtain a characteristic in which the external light component in each section increases, for example, to the right. When the charge amount in each section is viewed as the integrated intensity of the received light amount, the characteristics shown in FIG. 10B are obtained.

  Therefore, in the second calculation method, the processing shown in FIG. 11 is performed. Here, the light receiving unit 72 will be mainly described.

  First, in step S101, the charge amounts of the corresponding light receiving units 72 of the nine image data are compared, and two sections (reflected light sections) where the reflected light 34 arrives and other sections (outside light sections) are obtained. To detect. This is equivalent to detecting two received light integrated intensities having a high intensity and seven received light integrated intensities having a low intensity.

  Thereafter, in step S102, each received light integrated intensity in the seven external light sections is set as a reference intensity, and the time change of these seven reference intensity is converted into a function. In the example of FIG. 10A, since the amount of charge in the outside light section gradually increases with time, it can be functionalized as one linear function as shown by a straight line (dashed line) p. .

  Thereafter, in step S103, the reference intensities in the two sections (reflected light sections) corresponding to the two received light integrated intensities having high intensities are obtained from the functioned reference intensity distribution.

  Thereafter, in step S104, a corrected integrated intensity is obtained by subtracting the corresponding reference intensity from the two light receiving integrated intensities having a high intensity.

In step S105, the distance k to the object is calculated based on the two corrected integral intensities described above. That is, in the example of FIGS. 10A and 10B, since the reflected light 34 arrives between the first section T1 and the second section T2 of the second cycle C2, the distance calculation method described above is used. ,
Distance k = {d2 / (d1 + d2)} × L + 3L
It can ask for.

  If the two sections with the large received light integration intensity detected in step S101 are not temporally continuous, it is determined that the reflected light 34 has not arrived, and a ranging error is determined.

  In step S101, as a method of detecting two sections having a large received light integrated intensity, for example, a difference in received light integrated intensity for each adjacent section is obtained, and a section where the difference is greater than 0 and maximum is the reflected light 34. It is determined as the light reception start section, and the section where the difference is smaller than 0 and the absolute value is maximum is determined as the light reception end section of the reflected light 34. In this way, it is possible to detect the period in which the reflected light 34 has arrived at an early stage.

  By the way, the distance measuring system 10 according to the present embodiment stores the distance image in the first storage area of the buffer memory 44 and stores the grayscale image in the second storage area as shown in step S11 of FIG. I am doing so.

  Therefore, when the distance image and the grayscale image are stored in the storage device 48 by the storage unit 50, the distance measuring system 10 stores the distance image and the grayscale image in association with each other.

  As shown in FIG. 12, when the OS (operation system) operating on the CPU 26 has a function of managing data as shown in FIG. 12, the file name of the file in which the distance image is recorded and the gray image are recorded. Manage the file name of the selected file as a consecutive name. As a result, for example, when an access to a certain distance image file is performed, the grayscale image file related to the distance image file can be easily accessed, and complicated image file management can be easily performed. it can.

  As another association method, there is a method of managing the distance image and the grayscale image for each light receiving unit. In this method, as shown in FIG. 13, the density value and distance value of the light receiving unit 72 unit are registered in association with one file.

  Then, as shown in FIG. 14, a changeover switch 130 is provided in the first display 52 (corresponding to a two-dimensional image) connected to the distance measuring system 10, and the distance image display / You may make it switch to display / OFF of a grayscale image. In this case, since the distance image and the grayscale image are stored in association with each other as described above, the image display can be easily switched, and the processing time from the request to the response can be greatly shortened.

  In addition, the distance image can be displayed as a three-dimensional image by connecting the second display 54 (corresponding to the three-dimensional image) to the distance measuring system 10. In this case, the three-dimensional image can be selected from a three-dimensional polygon image obtained only from distance data, a three-dimensional model image obtained by mapping luminance data based on a grayscale image on the three-dimensional polygon image, and the like. Also in this case, since the distance image and the grayscale image are stored in association with each other as described above, the three-dimensional image can be easily switched, and the processing time from the request to the response can be greatly shortened. .

  Of course, the distance measuring device, the distance measuring method, and the distance measuring system according to the present invention are not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

It is a perspective view which shows the external shape of the ranging system which concerns on this Embodiment. It is a block diagram which shows the structure of the ranging system which concerns on this Embodiment. It is a timing chart which shows operation | movement of the ranging system which concerns on this Embodiment. It is explanatory drawing which shows schematic structure of an image pick-up element. It is explanatory drawing which shows the structure based on the potential of a light-receiving part. It is a timing chart for demonstrating the 1st calculation method when not considering external light. It is a timing chart for demonstrating the 1st calculation method when external light is considered. It is a flowchart which shows the algorithm of a 1st calculation method. It is a circuit diagram which shows the ranging calculation circuit comprised based on the algorithm of the 1st calculation method. FIG. 10A is a timing chart for explaining the second calculation method, and FIG. 10B is a characteristic diagram when the charge amount in each section is viewed as the integrated intensity of the received light amount. It is a flowchart which shows the processing operation by a 2nd calculation method. It is explanatory drawing which shows an example in the case of managing a distance image and a grayscale image in association with a file name. It is explanatory drawing which shows an example in the case of registering the gray value and distance value of a light-receiving part unit in association with one file. It is explanatory drawing which shows the example which provided the change switch of the distance image and the grayscale image in the 1st display (corresponding to a two-dimensional image). 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Ranging system 14 ... Light emission means 16 ... Light reception means 18 ... Calculation means 20 ... Irradiation light source 28 ... Pulse light 32 ... Imaging element 34 ... Reflected light 48 ... Memory | storage device 50 ... Storage part 52 ... 1st display 54 ... 1st 2 display 56 ... display unit 72 ... light receiving unit 74 ... photoelectric conversion unit 76a ... first storage unit 76b ... second storage unit 78a ... first vertical transfer path 78b ... second vertical transfer path 96 ... distance calculation unit 98 ... measurement Distance calculation circuit 100... Data readout circuit unit 102 .. Outside light section determination circuit unit 104... Distance measurement circuit unit 106. Offset amount determination circuit unit 108.

Claims (11)

A light emitting means for emitting pulsed light having a predetermined pulse width from a reference time;
The reflected light from the object irradiated with the pulsed light is received, the first charge amount accumulated in the first section over the period corresponding to the pulse width from the reference time, and the pulse width from the elapsed time of the first section. A light receiving means for obtaining a second charge amount accumulated in a second interval over a period corresponding to, and a third charge amount accumulated in a third interval over a period corresponding to the pulse width after the second interval elapses;
Calculating means for calculating a distance to the object based on the first charge amount, the second charge amount and the third charge amount obtained by the light receiving means;
The computing means is
A comparison unit for comparing the first charge amount, the second charge amount, and the third charge amount;
A distance calculation unit that calculates a distance based on the first interval or the second interval based on the first variable, the second variable, and the third variable;
The first variable, the second variable, the third variable, the first charge amount, the second charge amount, and the first variable according to the interval with the smallest charge amount among the first interval and the third interval. A selection unit for selecting a correspondence relationship with the third charge amount;
An adder;
Have
When the distance calculation unit is set to a set distance determined by the pulse width L, the first variable is Xa, the second variable is Xb, and the third variable is Xc,
{(Xb−Xc) / (Xa + Xb−Xc × 2)} × L
To calculate the distance,
When the section with the smallest charge amount is the third section, the selection unit sets the first variable Xa to the first charge amount, the second variable Xb to the second charge amount, and the third variable Xc to the third variable Xc. When the third charge amount is selected and the section with the smallest charge amount is the first section, the second variable amount is set to the first variable Xa, the third charge amount is set to the second variable Xb, Select the first charge amount for three variables Xc,
The adding unit adds 0 to the distance obtained by the distance calculation unit when the section with the smallest charge amount is the third section, and when the section with the least charge amount is the first section. The distance measuring device adding the set distance L to the distance obtained by the distance calculation unit. The distance measuring device according to claim 1,
A distance measuring apparatus characterized in that a measurement error occurs when the section with the smallest amount of charge is the second section. A light emitting means for emitting pulsed light having a predetermined pulse width from a reference time;
The light including the reflected light from the object irradiated by the pulsed light and the external light component is received in each of the n sections arranged in order for each period corresponding to the pulse width from the reference time. A light receiving means for obtaining the received light integrated intensity,
Comparing the n light receiving integrated intensity, and two light receiving integrated intensity greater intensity (first light receiving integrated intensity and the second light receiving integrated intensity), a small strength (n-2) number of detected received light integrated intensity Of the n sections, the reflected light arrives at two sections (first section and second section) corresponding to the first received integrated intensity and the second received integrated intensity, and the A comparison means that sets the reflected light section in which the external light component is incident and the other (n−2) sections as the external light section in which only the external light component is incident ;
The (n−2) received light integrated intensities having small intensities in the outside light section are set as reference intensities, and the time variation of (n−2) reference intensities is converted into a function to function as the reflected light section and the outside light section. Means for obtaining a distribution of reference intensities in n intervals including
Means for obtaining a first reference intensity and a second reference intensity corresponding to the first section and the second section in the reflected light section from the obtained distribution of the reference intensity;
The first corrected integrated intensity and the second corrected integrated intensity are obtained by subtracting the corresponding first reference intensity and second reference intensity from the first received light integrated intensity and the second received light integrated intensity in the reflected light section, respectively. Means,
Means for calculating a distance to the object based on the first correction integral intensity and the second correction integral intensity ;
The means for calculating the distance to the object is:
The set distance determined by the pulse width is L, the first correction integral intensity is d1, the second correction integral intensity is d2, and the interval from the reference time to the arrival of the reflected light interval among the n intervals. Where m is the number of
{D2 / (d1 + d2)} × L + m × L
And a distance k to the object is calculated to calculate a distance measuring device. A light emission step of emitting pulsed light having a predetermined pulse width from a reference time;
A first light receiving step of receiving reflected light from an object irradiated with the pulsed light in a first section over a period corresponding to the pulse width from the reference time to obtain a first received light integrated intensity;
A second light receiving step of receiving the reflected light in a second section over a period corresponding to the pulse width from the time when the first section has elapsed to obtain a second received light integrated intensity;
A third light receiving step of receiving the reflected light in a third section over a period corresponding to the pulse width from the second section elapsed time point to obtain a third received light integrated intensity;
A calculation step of calculating a distance to the object based on the first received light integrated intensity, the second received light integrated intensity, and the third received light integrated intensity;
The calculation step includes:
A comparison step of comparing the first received light integrated intensity, the second received light integrated intensity, and the third received light integrated intensity;
A distance calculating step of calculating a distance based on the first interval or the second interval based on the first variable, the second variable, and the third variable;
Of the first interval and the third interval, the first variable, the second variable, the third variable, the first received light integration intensity, and the second received light integration depending on the interval with the smallest received light integration intensity. A selection step of selecting a correspondence relationship between intensity and the third received light integrated intensity;
Adding step;
Have
In the distance calculation step, when the set distance determined by the pulse width is L, the first variable is Xa, the second variable is Xb, and the third variable is Xc,
{(Xb−Xc) / (Xa + Xb−Xc × 2)} × L
To calculate the distance,
In the selection step, when the section with the smallest received light integral intensity is the third section, the first received light integrated intensity is set to the first variable Xa, the second received light integrated intensity is set to the second variable Xb, and the third When the third received light integrated intensity is selected as the variable Xc, and the section with the smallest received light integrated intensity is the first section, the second received light integrated intensity is set as the first variable Xa, and the second received light intensity is set as the second variable Xb. 3 received light integrated intensity, the first received light integrated intensity is selected as the third variable Xc,
The adding step adds 0 to the distance obtained in the distance calculating step when the interval with the smallest received light integration intensity is the third interval, and the interval with the smallest received light integration intensity is the first interval. In this case, the distance measuring method is characterized in that the set distance L is added to the distance obtained in the distance calculating step. The distance measuring method according to claim 4,
A distance measuring method characterized in that a measurement error occurs when the received light integrated intensity received in the second light receiving step is regarded as a reference intensity. A light emission step of emitting pulsed light having a predetermined pulse width from a reference time;
The light including reflected light and ambient light component from the object illuminated by pulsed light, by receiving respectively, in the n which are arranged in order interval from the reference time for each period corresponding to the pulse width n A light receiving step for obtaining the received light integrated intensity ,
Comparing the n light receiving integrated intensity, and two light receiving integrated intensity greater intensity (first light receiving integrated intensity and the second light receiving integrated intensity), a small strength (n-2) number of detection light receiving integrated intensity Of the n sections, the reflected light arrives at two sections (first section and second section) corresponding to the first received integrated intensity and the second received integrated intensity, and A comparison step in which the external light component is the reflected light interval, and the other (n−2) intervals are external light intervals in which only the external light component is incident ;
The (n−2) received light integrated intensities having small intensities in the outside light section are set as reference intensities, and the time variation of (n−2) reference intensities is converted into a function to function as the reflected light section and the outside light section. Obtaining a distribution of reference intensities in n intervals including
Obtaining a first reference intensity and a second reference intensity corresponding to the first section and the second section in the reflected light section from the obtained distribution of the reference intensity;
The first corrected integrated intensity and the second corrected integrated intensity are obtained by subtracting the corresponding first reference intensity and second reference intensity from the first received light integrated intensity and the second received light integrated intensity in the reflected light section, respectively. Steps,
Calculating a distance to the object based on the first corrected integral intensity and the second corrected integral intensity ,
Calculating the distance to the object comprises:
The set distance determined by the pulse width is L, the first correction integral intensity is d1, the second correction integral intensity is d2, and the interval from the reference time to the arrival of the reflected light interval among the n intervals. Where m is the number of
{D2 / (d1 + d2)} × L + m × L
A distance measuring method, wherein a distance k to the object is calculated by calculating . The distance measuring method according to claim 6,
A distance measurement method, wherein a distance measurement error is generated when the first section and the second section are not temporally continuous. The distance measuring method according to claim 6,
The comparison step includes
Calculates the difference between the light receiving integrated intensity of each section, the sectional difference is at a maximum greater than 0, it is determined that the start section of the reflected light interval, the absolute value smaller than the difference is zero the period is the maximum, the ranging wherein determining that termination section of the reflected light section. A distance measuring device according to claim 1 or 2,
A distance image obtaining means for obtaining a distance image by calculating a distance corresponding to each light receiving unit in the distance measuring device;
A gray-scale image obtaining unit that obtains a gray-scale image corresponding to each light receiving unit based on a charge amount of the section with the smallest charge amount detected corresponding to each light receiving unit in the distance measuring device. Ranging system. The ranging system according to claim 9, wherein
A distance measuring system comprising image recording means for recording the distance image and the grayscale image in association with each other on a recording medium. The ranging system according to claim 9, wherein
Ranging is provided with data recording means for recording the distance data corresponding to each light receiving unit in the distance image and the light and dark data corresponding to each light receiving unit in the gray image in association with each light receiving unit on a recording medium. system.

Images