JP2008128792A - Distance image producing device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To create a distance image without being influenced by the light component of external light. <P>SOLUTION: Detection light is irradiated from an LED 10 toward a subject which is a distance measuring object. High-speed shutters 22, 32 are opened, only during a period synchronized with an irradiation timing of the detection light and makes the detection light reflected by the subject to enter each image sensor 23, 33. The first image sensor 23 receives light transmitted through the first BPF 21, transmitting a wavelength band including the wavelength of the detection light. The second image sensor 33 receives the light transmitted through the second BPF 31, transmitting a wavelength band near the transmission wavelength band of the first BPF 21. The second BPF 31 is adjusted so that the second image sensor 33 receives an external light component, as much as the same light-receiving amount as the external light component received by the first image sensor 23. The external light component is removed, by subtracting the number of pixels of the second image sensor 33 from the number of pixels of the first image sensor 23, and a distance image representing a distance to the subject by the number of pixels is produced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a distance image creating apparatus and method for creating a distance image representing a distance to a distance measurement object by a pixel value.

  Patent Document 1 discloses a distance image creating apparatus that creates a distance image that indicates a distance to a measurement object as a pixel value by a TOF (Time of Flight) method. The distance image creating apparatus of Patent Document 1 includes a light source that irradiates pulsed light onto an imaging space, and an image sensor that receives reflected light from a measurement object in the imaging space, and is irradiated with pulsed light. By synchronizing the period during which the image sensor receives the reflected light, the distance to the measurement object is captured as the amount of light received by the image sensor.

  According to the distance image creation apparatus as described above, it is possible to easily create still images and moving image data as mask images for cutting out only an image portion within a specific distance range, and using the mask images, For example, only a subject within a specific distance range in front of the background can be cut out from a normal moving image that is simultaneously captured and combined with another background image.

US Pat. No. 6,100,157

  The camera can create a distance image by using near-infrared light, infrared light, or the like so as not to affect a normally captured image. However, when receiving the light reflected on the subject, the infrared light component in the outside light is also received. For this reason, particularly in outdoor photography, there is a problem that the influence of the infrared light component in the outside light is increased, the accuracy of the distance image is lowered, or the distance image cannot be created.

  In order to solve the above problem, an object of the present invention is to provide a distance image creation apparatus and method that can create a distance image even outdoors, by eliminating the influence of an external light component.

  In order to achieve the above object, the distance image creating apparatus according to claim 1 forms an image of a light source that irradiates a distance measuring object in a pulsed manner with detection light having a predetermined wavelength, and a distance measuring object. And an optical path branching means for splitting the optical path into a first optical path and a second optical path, and light incident on the first optical path. 1st band pass filter which permeate | transmits the 1st wavelength range including the wavelength of the said detection light, and the light which permeate | transmitted this 1st band pass filter are received, and the electric charge according to the light reception amount is produced | generated A first image sensor on which a distance measuring object is imaged by the optical system on the light receiving surface, and a second optical path disposed on the light receiving surface, Transmitting light in the second wavelength range close to the first wavelength range, Receiving a second band-pass filter for receiving the same amount of received light as the external light component in the first wavelength range received by the first image sensor, and light transmitted through the second band-pass filter; A second image sensor having a plurality of pixels on the light receiving surface for generating a charge corresponding to the amount of received light, and a distance measuring object formed on the light receiving surface by the optical system; From the light receiving control means for controlling the light receiving period received by the second image sensor in synchronization with the irradiation of the detection light, from the pixel value obtained from the pixel of the first image sensor, from the pixel of the second image sensor Subtracting means for removing light components other than the detection light by subtracting the obtained pixel value between corresponding pixels is provided.

  The distance image creating apparatus according to claim 2, further comprising an operation control unit that stops the operation of the second image sensor when the signal level output from the second image sensor is smaller than a predetermined threshold value. is there.

  In the distance image creating apparatus according to claim 3, between the insertion position where the optical path branching means is inserted in the optical path and the retract position where the light from the optical system is incident only on the first bandpass filter by retracting from the optical path. A moving means for moving, and the operation control means is in a state in which the optical path branching means is moved to the retracted position via the moving means while the operation of the second image sensor is stopped. It is what I did.

  5. The distance image creating apparatus according to claim 4, wherein a light source for irradiating a detection light having a predetermined wavelength in a pulse shape toward the distance measurement object, an optical system for imaging the distance measurement object, and an incident A first band-pass filter that transmits a first wavelength band including the wavelength of the detection light is formed, and the light that has passed through the first band-pass filter is received, and according to the amount of light received A plurality of first pixels that generate a charge and the first image sensor that transmits light in a second wavelength region that is close to the first wavelength region among incident light and that is received by the first image sensor. A second bandpass filter is formed to receive the same amount of light received as the external light component in the wavelength region of the light. The light transmitted through the second bandpass filter is received, and a charge corresponding to the amount of light received A plurality of second pixels to be generated, the first An image sensor in which a distance measuring object is imaged by the optical system on a light receiving surface in which elements and second pixels are alternately arranged, and a light receiving period in which the image sensor receives light is synchronized with the detection light irradiation. Light other than the detection light by subtracting the pixel value obtained from the second pixel in the vicinity of the first pixel from the pixel value of the pixel obtained from the first pixel. Subtracting means for removing a component and creating a distance image representing the distance to each part of the distance measurement object corresponding to each pixel value is provided.

  In the distance image creation method according to claim 5, the detection light having a predetermined wavelength is emitted from the light source toward the distance measurement object in a pulse shape, and at a predetermined light receiving period at a timing synchronized with the irradiation of the detection light. The light transmitted through the first wavelength region including the wavelength of the detection light is received by the first pixel, and the light transmitted through the second wavelength region close to the first wavelength region is transmitted to the second pixel. Light components other than the detection light are removed by receiving light at the pixels and subtracting the pixel value obtained from the second pixel from the corresponding pixel value from the pixel value obtained from the first pixel.

  The distance image creating method according to claim 6, wherein light is branched into a first image sensor provided with a plurality of the first pixels and a second image sensor provided with a plurality of the second pixels. Make it incident.

  The distance image creating method according to claim 7, wherein a plurality of the first pixels and a plurality of the second pixels are provided on the same light receiving surface, and the first pixels and the second pixels are alternately arranged. A second pixel adjacent to the first pixel is a second pixel corresponding to the first pixel, using the arrayed image sensor.

  According to the present invention, the detection light from the light source is irradiated toward the distance measurement object, and the reflected detection light is received through the first wavelength region including the wavelength of the detection light. The light component other than the detection light is removed by receiving light in the second wavelength region close to the first wavelength region and subtracting the latter light reception result from corresponding pixels from the former light reception result. Therefore, the pixel value excluding the influence of the external light component can be obtained, and a distance image can be created even outdoors.

  FIG. 1 shows a distance image creating apparatus according to a first embodiment of the present invention. The distance image creating apparatus 2 creates a distance image by detecting a distance based on the TOF (Time of Flight) method until the detection light returns after being reflected by the measurement object from irradiation of the detection light. Is to be detected as the amount of light received at each pixel of the image sensor. The distance image is created as a still image or moving image data. The distance image creation device 2 includes an LED 10, an optical system 11, a half mirror 12, a first measurement system, a second measurement system, a shutter drive circuit 13, a timing signal generation circuit 14, a difference calculation unit 15, a correction calculation unit 16, a distance The conversion unit 17 includes a system control unit 18 that controls these units in an integrated manner.

  The LED 10 is a light source for creating a distance image, and is driven by the drive circuit 19 to irradiate the imaging space where the measurement object for distance measurement is arranged with pulsed detection light. The measurement object may be stationary or moving. The detection light has a predetermined wavelength (hereinafter referred to as a light source wavelength), and the light source wavelength does not affect the photographing in the visible light region, and the near infrared light that is not easily affected by the heat of the subject, that is, infrared rays. It is set in the area. In this example, the detection light is directly modulated, but may be externally modulated. Further, the light source is not limited to the LED, and the detection light may be a single wavelength or may have a certain spread in wavelength.

  The optical system 11 has a configuration similar to that of a photographic lens or the like, and forms an image of light reflected by the subject. The half mirror 12 as an optical path branching unit transmits half of the light from the optical system 11 toward the first measurement system and reflects the other half toward the second measurement system. The optical path branching means is not limited to a half mirror as long as the optical path can be branched. For example, a dichroic prism may be used to provide the functions of the BPFs 21 and 31 described later.

  The first measurement system includes a first BPF 21, a first high-speed shutter 22, a first image sensor 23, a CDS circuit 24 that processes a signal from the first image sensor 23, an AMP 25, and an A / D converter 26. The first BPF 21, the first high-speed shutter 22, and the first image sensor 23 are arranged in order from the mirror 12 side, and light transmitted through the half mirror 12 is incident on the first BPF 21.

  The first BPF 21 is a band-pass optical filter that transmits light in a specific wavelength range. For example, the center wavelength of the first BPF 21 is the detection light so that the light source wavelength of the detection light emitted from the LED 10 is transmitted. The transmission wavelength region (hereinafter referred to as the first transmission wavelength region) is determined so as to coincide with the wavelength.

  The first high-speed shutter 22 as the light receiving control means is constituted by, for example, an electro-optical shutter, and can be switched at high speed between an open state that transmits light from the first BPF 21 and a closed state that blocks light. Yes. The first high-speed shutter 22 is driven by the shutter drive circuit 13 based on a measurement distance range in which the distance is to be measured, an opening / closing pattern determined based on the lighting time of the LED 10, a phase difference of light emission from the LED 10, and the like, as will be described later. Is done.

  As the light receiving control means, in addition to what is driven to transmit and block incident light as described above, the operation of amplifying and outputting incident light and not outputting (blocking) can be switched at high speed. It can be a microchannel plate (MCP) or the like. The position of the light receiving control means can be arranged on the photographing lens side with respect to the first BPF 21 as long as it transmits and blocks the incident light, and is arranged on the optical system 11 side with respect to the half mirror 12 to be described later. You may make it common with 2 measurement systems. Moreover, it is necessary to arrange | position so that the light after permeate | transmitting BPF injects the thing which does not output incident light itself like a microchannel plate. The shutter function built in the image sensor can also be used as the light reception control means.

  The first image sensor 23 is driven by a drive signal from the timing generator 14. The first image sensor 23 has a large number of pixels arranged in a matrix on the light receiving surface, and each pixel performs photoelectric conversion, accumulates charges according to the amount of received light, and transfers the respective charges to transfer the first charge. Output image signal. Since the light transmitted through the first BPF 21 and the first high-speed shutter 22 is incident on the first image sensor 23, a first image signal corresponding to the amount of light received in the first transmission wavelength region is output. As the first image sensor 23, for example, a CCD type image sensor is used, but a C-MOS type may be used instead of the CCD type.

  The first image signal from the first image sensor 23 is sent to the CDS circuit 24. The CDS circuit 24 removes a reset noise component generated when converting the charge accumulated in each pixel into a voltage signal (image signal). The AMP 25 amplifies the first image signal from the CDS circuit 24 with a predetermined gain. The A / D converter 26 operates in synchronization with the operation of the first image sensor 21, samples and digitally converts the first image signal for each pixel, and first image data including pixel values corresponding to each pixel. Is generated. The first image data is sent to the difference calculation unit 15.

  The second measurement system includes a second BPF 31, a second high-speed shutter 32, a second image sensor 33, a CDS circuit 34, an AMP 35, and an A / D converter 36, and the configuration of each part is a half mirror of the second BPF 31. 12 is the same as the first imaging system except that the light reflected by 12 is incident and the wavelength range (hereinafter referred to as the second transmission wavelength range) transmitted by the second BPF 31 is different, and the operation timing is also the same. It has become. The second measurement system is provided to eliminate the amount of received external light component included in the light in the first transmission wavelength range received by the first image sensor 23, and the second image sensor 33 outputs the second measurement system. The second image data obtained by digitally converting the second image signal is sent to the difference calculation unit 15.

  When external light from other light sources outdoors or indoors is incident, the amount of external light components received by the first image sensor 23 via the first BPF 21 and the second image sensor 33 receive light via the second BPF 31. The characteristics of the second BPF 31, that is, the center wavelength, the half-value width, the spectral transmittance, and the like are determined in consideration of the spectral sensitivity of each of the image sensors 23 and 33 so that the received light amount of the external light component is the same. . As a result, the received light amount of the first image sensor 23 receiving the detection light can be obtained as the difference between the received light amount of the first image sensor 23 and the received light amount of the second image sensor 33.

  Note that the received light amount of the external light component received by the first image sensor 23 via the first BPF 21 is the same as the received light amount of the external light component received by the second image sensor 33 via the second BPF 31. This means that the substantial amount of light received in the sense that the same pixel value as the pixel value corresponding to the amount of received external light component received by the image sensor 23 is obtained from the second image sensor 33. Further, the amplification of amplifying the second image signal output from the second image sensor 33 without making the amount of light received by the second image sensor 33 of the external light component transmitted through the second BPF 31 the same as that of the first image sensor 23. Also by adjusting the rate or correcting the image data obtained therefrom, the second image sensor 33 can obtain the same pixel value as the pixel value corresponding to the amount of received external light component received by the first image sensor 23. . However, it is easier and faster to determine the center wavelength, the half width, the spectral transmittance, etc. of the second BPF 31 to obtain the same received light amount (pixel value) as described above.

  As shown in FIG. 2, the first transmission wavelength region of the first BPF 21 is determined so as to transmit the light source wavelength of the detection light, and the second transmission of the second BPF 31 is on the short wavelength side in the vicinity of the first transmission wavelength region. The wavelength range is set. Since normal outside light such as sunlight does not change abruptly if the wavelength difference is small, if the second transmission wavelength region is set in the vicinity of the first transmission wavelength region in this way, the second transmission wavelength region The received light amount of the external light component in the first transmission wavelength region can be detected as the received light amount of the external light component.

  When the second transmission wavelength region is set in the vicinity of the first transmission wavelength region, the second transmission wavelength region may be set on the long wavelength side of the first transmission wavelength region. In addition, it is possible to transmit light on each of the long wavelength side and the short wavelength side of the first transmission wavelength region, and use, for example, an average value of each transmitted light amount in these wavelength regions. And adjusting the transmittance on the short wavelength side so that the amount of the external light component received through the respective wavelength ranges is the same as the amount of the external light component received by the first image sensor 23. May be.

  The difference calculation unit 15 serving as a subtracting unit obtains a pixel value as a detection light component reflected from the subject by excluding an external light component in the first transmission wavelength region from each pixel value of the first image data. A process of subtracting the pixel value of the second image data from the pixel value of the first image data between corresponding pixels is performed for each pixel to create difference image data. The difference image data includes main measurement difference image data generated from each image data obtained by a main measurement operation described later and sub measurement difference image data generated from each image data obtained by a sub measurement operation.

  The correction calculation unit 16 performs sub-measurement difference image data with respect to main measurement difference image data so that each pixel value corresponds to the distance to the subject for a subject whose reflectance is not constant or uniform. A distance image is created by performing correction based on. When the reflectance of each part of the subject is constant, each pixel value of the main measurement difference image data depends on the distance to the subject, but the reflectance of each part of a normal subject is not constant Moreover, since it is not uniform, the correction | amendment by the correction calculating part 16 is performed.

  The distance conversion unit 17 converts the pixel value of the distance image created by the correction calculation unit 16 into an actual distance. The distance image created in this way is sent to a computer for image processing via a predetermined interface, for example. The image processing computer receives a normal image captured in the visible light region in synchronization with the same range as the distance image creation device, and processes the normal image based on the distance image.

  As processing based on the distance image, for example, an image area within a specific distance range is extracted from the normal image based on the distance image, and the extracted image area is combined with another image that has been taken separately. The extraction can be performed by referring to the corresponding pixel of the distance image for each pixel of the normal image. By continuously performing such processing for each frame to be photographed, it is possible to synthesize a subject with a moving image. Of course, it can be performed even in the case of a still image.

  FIG. 3 shows the detection light irradiation timing and the opening / closing timing of the high-speed shutter 23.33 in the main measurement operation and the sub-measurement operation.

  The main measurement operation is to receive the detection light reflected by the subject so as to receive light with a light receiving time corresponding to the distance of the subject. In this main measurement operation, as shown in FIG. 3A, the LED 10 is turned on for a time Tp, and detection light having a pulse width of the time Tp is irradiated toward the subject. The high-speed shutters 22 and 32 are opened with a delay of time ΔT from the detection light irradiation timing, and are opened only for the period of time Ts1 and then closed to block light. Such a main measurement operation is performed during one frame period of the image sensors 23 and 33.

  The time Tp, the time ΔT, and the time Ts1 are determined according to the measurement distance range of the subject whose distance is to be measured. For example, when “Ts1 = Tp” and the speed of light is “c”, for example, the distance of the subject in the distance range from “(ΔT−Tp) · c / 2” to “(ΔT + Tp + Ts1) · c / 2” is set. Can be measured. Note that, for example, ΔT can be increased or decreased sequentially, and the measurable distance range can be sequentially shifted to perform measurement in a desired distance range.

  The sub-measurement operation is performed to correct the pixel value obtained in the main measurement operation to a pixel value corresponding to the distance by eliminating the influence on the reflectance of the reflection part of the subject. Each unit is operated so that the detected light is received as a received light amount proportional to the reflectance of the reflection part of the subject and inversely proportional to the square of the distance.

  As shown in FIG. 3B, in the sub measurement operation, the detection light having the pulse width of the time Tp is irradiated as in the main measurement operation. On the other hand, each of the high-speed shutters 22 and 32 is opened in the period of time Ts2 after the start of detection light irradiation, and the time Ts2 is long enough to receive the entire amount of detection light reflected from the subject to be measured. Decided. In this example, each of the high-speed shutters 22 and 32 is opened at the same time as the detection light irradiation starts. However, when the detection light reflected by the subject to be measured within the measurement distance range starts to enter, For example, the open state may be delayed by a time ΔT from the start of detection light irradiation.

  In this example, the main measurement operation is performed once during one frame period and the sub measurement operation is performed during the next one frame period. For example, a plurality of main measurement operations may be performed during one frame period. The operation may be performed a plurality of times in one frame period. Further, the sub-measurement operation may be performed once or a plurality of times every plural main measurement operations.

  Next, the operation of the above embodiment will be described. When creating a distance image, the LED 10 and the optical system 11 are pointed at a subject whose distance is to be measured, and then the creation of the distance image is instructed by operating the operation unit 18a (see FIG. 1). When the creation of the distance image is instructed, the system control unit 18 initializes each unit, and then the main measurement operation is started, and pulsed detection light having a width of time Tp is emitted from the LED 10.

  Of the detection light emitted from the LED 10, the light incident on the subject is reflected by the incident portion of the subject and enters the optical system 11. At this time, if the subject is irradiated with external light from a light source such as a room light or sunlight in addition to the LED 10, the external light component reflected by the subject is also incident on the optical system 11. . Then, half of the light incident on the optical system 11 passes through the half mirror 12 and enters the first BPF 21, and the light component in the first transmission wavelength region of the light enters the first high-speed shutter 22. In addition, the remaining half of the light incident on the optical system 11 is reflected by the half mirror 12 and incident on the second BPF 31, and the light component in the second transmission wavelength region thereof is incident on the second high-speed shutter 32.

  The high-speed shutters 22 and 32 are opened after a time ΔT from the start of irradiation of the detection light, and the high-speed shutters 22 and 32 are closed after the state is maintained for the time Ts1. During this open state, only the light transmitted through the BPFs 21 and 31 and incident on the high-speed shutters 22 and 32 is received by the image sensors 21 and 31. As a result, the light received by each pixel of the image sensors 23 and 33 is received for a light reception time corresponding to the distance to the portion of the subject from which the light incident on the pixel is reflected.

  Thereby, in each pixel of the first image sensor 23, electric charges corresponding to the amount of light received in the first transmission wavelength region that is transmitted while the high-speed shutter 22 is in the open state are accumulated. At this time, the light received by each pixel includes a detection light component reflected by the subject and an external light component in the first transmission wavelength range in which the external light is reflected by the subject. Further, in each pixel of the second image sensor 33, charges corresponding to the amount of light received in the second transmission wavelength region are accumulated while the high-speed shutter 32 is in the open state, but light is received by each pixel. The light is only the external light component in the second transmission wavelength region in which the external light is reflected by the subject, and the amount of light received by each pixel is substantially the same as that due to the external light component received by the corresponding pixel of the first image sensor 23. become.

  As described above, the main measurement operation is performed within one frame period. When the next frame period is reached, the charges accumulated in the pixels of the image sensors 23 and 33 are transferred, and the image signals from the image sensors 23 and 33 are transferred. Is output as Then, the first image signal from the first image sensor 23 is converted into first image data through the CDS circuit 24, the AMP 25, and the A / D converter 26, and sent to the difference calculation unit 15. The second image signal from the second image sensor 33 is converted into second image data via the CDS circuit 34, the AMP 35, and the A / D converter 36 and sent to the difference calculation unit 15.

  When the first image data and the second image data are input, the difference calculation means 15a calculates the second image data from the pixel values of the first image data between corresponding pixels of the first image data and the second image data. A process of subtracting the pixel value is performed, and main measurement difference image data for one screen is generated.

  Further, in the next frame period after the main measurement operation, the sub-measurement operation is performed, and pulsed detection light having a width of time Tp is emitted from the LED 10. Then, the detection light reflected by the subject and the external light component reflected by the subject from outside light from the light source enter the optical system 11. Half of the light incident on the optical system 11 passes through the half mirror 12 and enters the first high-speed shutter 22 via the first BPF 21, and the other half is reflected by the half mirror 12 and passes through the second BPF 31. Incident on the high-speed shutter 32.

  Each of the high-speed shutters 22 and 32 is opened for a time Ts2 in synchronization with the detection light irradiation, and only light incident during this time enters the image sensors 23 and 33 and is received by each pixel. The electric charge according to is accumulated. In the light received by each pixel of the first image sensor 23, the detection light component reflected by the subject and the external light component in the first transmission wavelength region where the external light is reflected by the subject are the same as in the main measurement operation. included. However, even if the detected light component is within the measurement distance range, it is a light receiving time that is unrelated to the distance, and its length is time Tp. The light received by each pixel of the second image sensor 33 is only the outside light component in the second transmission wavelength region without including the detection light component. In this case as well, the received light amount of each pixel corresponds to the second light sensor. This is almost the same as that of the external light component received by the pixels of one image sensor 23.

  In the next frame period of the sub-measurement operation, an image signal based on the light reception result of the sub-measurement operation is output from each of the image sensors 23 and 33, and the first image data and the first image data through the CDS circuit, AMP, and A / D converter, respectively. The second image data is converted and sent to the difference calculation unit 15. Then, a process of subtracting the pixel value of the second image data from the pixel value of the first image data between corresponding pixels of the first image data and the second image data is performed, and the sub-measurement difference image data for one screen Is generated.

  In any measurement operation, the second image sensor is configured to receive the same amount of received light as the external light component received by the first image sensor 23 from the pixel value obtained by the light reception of the first image sensor 23. Since the 33 corresponding pixel values are subtracted, each pixel value of each obtained difference image data approximates the result of receiving the detected light component with high accuracy.

  The main measurement difference image data and the sub measurement difference image data calculated by the difference calculation unit 15 as described above are sent to the correction calculation unit 16. The correction calculation unit 16 calculates the ratio of the pixel value of the main measurement difference image data to the pixel value of the sub measurement difference image data between corresponding pixels of the main measurement difference image data and the sub measurement difference image data. Processing is performed for each pixel, and a distance image in which each pixel value indicates the distance to the subject is created.

  As described above, the distance to the subject can be accurately determined even when light from the same wavelength range as the detection light or the first transmission wavelength range of the first BPF 21 is irradiated from other light sources outdoors or indoors. A measured distance image is created. Then, the distance image created by the correction calculation unit 16 is sent to the distance conversion unit 17 and converted so that each pixel value becomes an actual distance, which is sent to an image processing computer, for example.

  FIG. 4 shows a second embodiment in which the operation of the second measurement system is stopped when light in the second transmission wavelength region is not detected. In addition, except being demonstrated below, it is the same as that of the said 1st Embodiment, The same code | symbol is attached | subjected to the substantially same structural member, and the description is abbreviate | omitted.

  In this example, the system control unit 10 examines the second image signal output from the second image sensor 33, and if the second image signal is smaller than a predetermined threshold value, the second control signal is not affected by outside light. It is determined that the detection light can be received by one measurement system, and each part of the second measurement system including the second image sensor 33 is turned OFF. Further, by operating the operation unit 18a and selecting OFF of the second image sensor 33 in a shooting environment where it is clear that there is no influence of external light, each unit of the second measurement system is turned OFF. is there.

  According to this, the power consumption can be reduced by turning off each part of the second measurement system. When each part of the second measurement system is turned off, the distance image is created without creating the difference image data.

  5 and 6, the light from the optical system 11 may be directly incident on the first measurement system when each part of the second measurement system is turned off. In this example, as shown by a solid line in FIG. 5, the half mirror 41 is inserted into the optical path of the optical system 11 and transmits half of the light from the optical system 11 toward the first measurement system, and the remaining part An insertion position where half is reflected toward the second measurement system, and a retraction position where the light from the optical system 11 is retracted and all of the light from the optical system 11 is incident on the first measurement system, as indicated by a two-dot chain line. It can move freely between. When each part of the second measurement system is turned OFF, the half mirror 41 is moved from the insertion position to the retracted position by the actuator 42. Thereby, when it is not necessary to operate each part of a 2nd measurement system, the light quantity to a 1st measurement system can be increased and a substantial sensitivity can be raised.

  7 and 8 show a third embodiment using one image sensor. In addition, except being demonstrated below, it is the same as that of 1st embodiment, the same code | symbol is attached | subjected to the substantially same structural member, and the description is abbreviate | omitted.

  As shown in FIG. 7, the distance image creating apparatus is provided with one image sensor 51 so that light from the optical system 11 enters through a high-speed shutter 52. The high-speed shutter 52 is driven by the shutter drive circuit 13 in the same manner as the high-speed shutter of the first embodiment.

  As shown in FIG. 8, a large number of IR1 pixels 51a and IR2 pixels 51b are provided on the light receiving surface of the image sensor 51. These IR1 pixels 51a and IR2 pixels 51b are alternately arranged in the vertical direction and the horizontal direction. It is a staggered arrangement. Each IR1 pixel 51a is provided with a band-pass filter that transmits the first transmission wavelength band on the front surface thereof, and receives light in the first transmission wavelength band. Each IR2 pixel 51b is provided with a band-pass filter that transmits the second transmission wavelength band on the front surface thereof, and receives light in the second transmission wavelength band.

  After passing through the CDS circuit 24, the AMP circuit 25, and the A / D converter 26, the image signal corresponding to the IR1 pixel 51a is the first image data, and the image signal corresponding to the IR2 pixel 51b is the second image data for each pixel element. Is converted into a digital signal and sent to the difference calculation unit 15. The difference calculation unit 15 obtains, for each IR1 pixel 51a, difference image data obtained by subtracting the second image data of the IR2 pixel 51b adjacent thereto from the first image data of the IR1 pixel 51a. Thereby, it is possible to exclude the amount of light substantially the same as the external light component in the first transmission wavelength range received by the IR1 pixel 51a from the pixel value of the IR1 pixel 51a.

  When obtaining the difference image data, the image data of the IR2 pixel 52b at any of the upper, lower, left and right positions of the target IR1 pixel 51a may be used, or the image data of the two IR2 pixels 52b, upper, lower, left and right. Or an average value of image data of surrounding IR2 pixels 52b may be used. Further, the IR1 pixels 51a and the IR2 pixels 51b are arranged in a staggered pattern, but the IR1 pixels 51a and the IR2 pixels 51b are alternately arranged in the horizontal direction, and the same type of pixels are arranged in a row in the vertical direction. Alternatively, the IR1 pixels 51a and the IR2 pixels 51b may be alternately arranged in the vertical direction, and the same type of pixels may be arranged in a row in the horizontal direction.

  Various methods can be employed to associate the pixels of the image sensor that captures the subject with visible light. For example, when the number of pixels of the image sensor 51 is the same as the number of pixels of the image sensor 51 that captures a subject with visible light, each pixel value corresponding to the IR1 pixel 51a on the left or right of the IR2 pixel 51b or the surrounding IR2 pixel 51b is used. May be used, or a pixel value corresponding to any one of the surrounding IR1 pixels 51a may be used.

  FIG. 9 shows a fourth embodiment in which a single photographing lens is used to photograph a subject with visible light and the distance is measured by a distance image creation device. A half mirror 55 is disposed behind the optical system 11. The half mirror 51 transmits half of the light from the optical system 11 toward the photographing device 56 and reflects the remaining half toward the half mirror 12 of the distance image creating device 57. The ratio of the amount of light transmitted and reflected by the half mirror 51 is not limited to 1: 1.

  The photographing device 56 photographs the subject with visible light by the image sensor 58, and a band pass filter 59 that transmits only visible light is disposed between the half mirror 51 and the image sensor 58. The image sensor 58 receives visible light transmitted through the half mirror 51 and the band pass filter 59 and outputs an image signal. The distance image creating device 57 is the same as the first embodiment except that the optical system 11 is shared with the photographing device 56 as described above.

  According to this, a distance image in the same range as the imaging range by the imaging device 56 can be easily created by the distance image creation device 57. The distance image creation device is not limited to that of the first embodiment, but may be that of another embodiment.

It is a block diagram which shows the structure of the distance image production apparatus which implemented this invention. It is a graph which shows the transmission wavelength range of a 1st, 2nd band pass filter. It is a timing chart which shows the irradiation timing of detection light, and the opening / closing timing of a high-speed shutter. It is a flowchart which shows the process of 2nd Embodiment which stops the action | operation of a 2nd measurement system, when the output of a 2nd image sensor is smaller than a threshold value. It is a block diagram which shows the principal part structure of the distance image creation apparatus in the example which retracts a half mirror from the optical path of an imaging lens, when stopping the action | operation of a 2nd measurement system. It is a flowchart which shows the process in the example which retracts a half mirror from the optical path of an imaging lens. It is a block diagram which shows the structure of the distance image creation apparatus in 3rd Embodiment which has arrange | positioned two types of pixels on one image sensor. It is explanatory drawing which shows the arrangement | sequence of the pixel on the light-receiving surface of the image sensor in 3rd Embodiment. It is a principal part block diagram which shows 4th Embodiment which shared the imaging device and the optical system.

Explanation of symbols

2 Distance image creation device 10 Light source 11 Shooting lens 12, 41 Half mirror 15 Difference calculation unit 16 Correction calculation unit 21, 31 Band pass filter 22, 32 High-speed shutter 23, 33, 51 Image sensor 42 Actuator 51a, 51b Pixel

Claims (7)

In a distance image creation device that creates a distance image representing a distance to each part of a distance measurement object corresponding to each pixel value,
A light source that irradiates a distance measurement object in a pulsed manner with a predetermined wavelength of detection light; and
An optical system for imaging a distance measurement object;
An optical path branching unit arranged in the optical path of the optical system and splitting the optical path into a first optical path and a second optical path;
A first bandpass filter that is disposed in the first optical path and transmits a first wavelength region including a wavelength of the detection light among incident light;
The light receiving surface has a plurality of pixels that receive the light transmitted through the first bandpass filter and generate charges according to the amount of light received, and a distance measurement object is formed on the light receiving surface by the optical system. A first image sensor to be imaged;
The first wavelength range that is arranged in the second optical path, transmits light in a second wavelength range close to the first wavelength range among incident light, and is received by the first image sensor. A second bandpass filter for receiving the same amount of received light as the external light component of
The light receiving surface has a plurality of pixels that receive light transmitted through the second bandpass filter and generate charges according to the amount of light received, and a distance measurement object is formed on the light receiving surface by the optical system. A second image sensor to be imaged;
A light receiving control means for controlling a light receiving period received by the first and second image sensors in synchronization with the irradiation of the detection light;
Subtracting means for removing light components other than detection light by subtracting pixel values obtained from the pixels of the second image sensor from corresponding pixels from pixel values obtained from the pixels of the first image sensor; A range image creating apparatus comprising:   2. The distance image creation according to claim 1, further comprising an operation control means for stopping the operation of the second image sensor when a signal level output from the second image sensor is smaller than a predetermined threshold value. apparatus.   And a moving means for moving between the insertion position where the optical path branching means is inserted in the optical path and the retracted position where the light from the optical system enters only the first bandpass filter by retreating from the optical path 3. The control unit is configured to move the optical path branching unit to the retracted position via the moving unit while the operation of the second image sensor is stopped. The described distance image creation device. In a distance image creation device that creates a distance image representing a distance to each part of a distance measurement object corresponding to each pixel value,
A light source that irradiates a distance measurement object in a pulsed manner with a predetermined wavelength of detection light; and
An optical system for imaging a distance measurement object;
A first bandpass filter that transmits a first wavelength region including the wavelength of the detection light among incident light is formed, and the light that has passed through the first bandpass filter is received, and the amount of received light is A plurality of first pixels that generate a corresponding charge, and the first image sensor that receives light in a second wavelength region that is close to the first wavelength region among incident light and that is received by the first image sensor. A second bandpass filter for receiving the same amount of light received as the external light component in the wavelength range of 1 is formed, the light transmitted through the second bandpass filter is received, and the charge corresponding to the amount of light received An image sensor in which a distance measurement object is imaged by the optical system on a light receiving surface in which the first pixels and the second pixels are alternately arranged;
A light receiving control means for controlling a light receiving period received by the image sensor in synchronization with the irradiation of the detection light;
By subtracting the pixel value obtained from the second pixel in the vicinity of the first pixel from the pixel value obtained from the first pixel, light components other than the detection light are removed, and each pixel value A distance image creating apparatus comprising: a subtracting unit that creates a distance image representing a distance to each part of the distance measurement target object corresponding to. In the distance image creation method for creating a distance image representing the distance to each part of the distance measurement object corresponding to each pixel value,
A detection light having a predetermined wavelength is radiated from a light source toward the distance measurement object in a pulse shape, and the first light including the wavelength of the detection light is included in a predetermined light receiving period at a timing synchronized with the irradiation of the detection light. Light transmitted through the wavelength band is received by the first pixel, and light transmitted through the second wavelength band close to the first wavelength band is received by the second pixel, from the first pixel. A distance image creating method, wherein a light component other than detection light is removed by subtracting a pixel value obtained from the second pixel from corresponding pixel values from a pixel value obtained.   6. The light is branched and made incident on a first image sensor provided with a plurality of the first pixels and a second image sensor provided with a plurality of the second pixels. Distance image creation method.   A plurality of the first pixels and a plurality of the second pixels are provided on the same light receiving surface, and an image sensor in which the first pixels and the second pixels are alternately arranged is used. 6. The distance image creating method according to claim 5, wherein the second pixel adjacent to the second pixel is a second pixel corresponding to the first pixel.

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