JP2009042114A - Apparatus and method for extracting light-sectioning line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the processing of inputting luminance information of pick-up images including images of line light irradiated to the surface of a moving object to be measured and extracting light-sectioning lines on the basis of the inputted information at high speed. <P>SOLUTION: The processing of parallel input of luminance information of a plurality of pixel blocks, which is acquired by dividing one horizontal line of a pixel group, by a circuit 610 for every pixel block; a series of a plurality of stages of the processing, by each of circuits 611a-611d, of a comparison of every two items of luminance information among all the luminance information recorded in one previous stage on the side of its previous stage and the processing of the recording of luminance information of one having higher luminance and its coordinate information; and the processing of a comparison of the luminance information recorded by the circuits 612 in its final stage and luminance information recorded last time and the recording of maximum-luminance information and coordinate information of one having higher luminance are parallelly executed in synchronization with prescribe clock signals CLK. The maximum-luminance information and its coordinate information is sequentially and additionally written in an SDRAM 62 in synchronization with horizontal synchronizing signals Hsync, and the maximum information is initialized in synchronization with the horizontal synchronizing signals. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides a captured image from an imaging element that captures a two-dimensional image including an image of line light (image of a light cutting line) irradiated on the surface of a relatively moving object to be measured (such as the surface of a rotating tire). The present invention relates to a light cutting line extraction device and a light cutting line extraction method for inputting luminance information of each pixel in and extracting an image of the light cutting line based on the input luminance information.

A tire has a structure in which various materials such as rubber, chemical fiber, and steel cord are laminated. If there is an uneven part in the laminated structure, the part with relatively weak pressure resistance when filled with air. In this case, a raised portion (convex portion) called a bulge and a recessed portion (concave portion) called a dent or a depression are generated. Tires with such shape defects as bulges and dents need to be inspected and excluded from shipment due to safety issues or poor appearance.
Conventionally, tire shape defects are inspected by detecting the surface height of multiple points with a contact or non-contact point measuring sensor while rotating the tire with a rotating machine, and determining the tire surface from the distribution of the surface height. It has been done by measuring the shape. However, in the inspection of shape defects based on tire shape measurement using point measurement type sensors, the shape of the entire surface to be detected for shape defects in tires is exhausted due to the restrictions on the number of sensors arranged and the inspection time. There was a problem that it was not possible to measure, and detection of shape defects was likely to occur.
On the other hand, in Patent Document 1, the surface of a rotating tire is irradiated with slit light (line light) to capture an image of the slit light, and the shape is detected by a light cutting method based on the captured image. A technique for measuring the surface shape of the film is shown. According to the technique disclosed in Patent Document 1, it is possible to comprehensively (continuously) measure the entire shape of a shape defect detection target surface (a tire sidewall surface or a tread surface) in a tire. Can be prevented from being missed.

By the way, the inspection time allowed for the inspection of the shape defect of the tire is about 1 second per tire. Further, in the measurement of the tire shape by the light cutting method, in order to distinguish the image of the light cutting line from the characters written on the tire surface, at least the line width (about 1 mm) of the characters in the circumferential direction of the rotating tire. It is necessary to perform imaging with a spatial resolution of. In order to satisfy the requirements of the inspection time and spatial resolution, it is necessary to capture 2000 frames per second for passenger car tires and 4000 frames per second for larger truck or bus tires. On the other hand, recent imaging devices have been accelerated in imaging processing, and a high-speed type imaging device represented by a COMS sensor can capture images at a high speed of 2000 to 4000 frames per second.
In the shape measurement by the light cutting method, a process of extracting a light cutting line image (line light image) from each captured image (image for one frame), that is, luminance information of each pixel constituting the captured image. It is necessary to perform image processing for detecting the position (coordinates) of the light cutting line with high brightness based on the image, and obtain the surface shape (surface height) of the tire from the extracted image (that is, the coordinates) of the light cutting line. . Usually, the extraction process of the light section line is performed by specifying the position (X coordinate) of the pixel having the maximum luminance for each pixel group (each position in the Y coordinate) for one horizontal line in the captured image. In the tire shape defect inspection, the light cutting line extraction processing occupies most of the calculation load in the processing based on the captured image (luminance information of each pixel). Note that Patent Document 1 shows an example in which the light cutting line extraction processing is executed by an MPU (microcomputer) including a CPU, a ROM, and a RAM.
In recent tire shape defect inspection processes, there is a high demand for obtaining a determination result of presence / absence of a shape result in real time as much as possible, compared to a high-speed tire surface imaging process (for example, 1 second).
Also, when measuring the shape of a measurement object other than a tire by scanning the surface of the measurement object using the optical cutting method, the shape of the measurement target surface must be measured within a limited time. If it is necessary to measure the shape of the measurement target surface with a very high spatial resolution within a limited time, a large number of captured images captured at a high imaging rate or a high resolution (pixel There is a need to complete the process of extracting a light section line within a limited time for a captured image (which has a large number).
In addition, as a method of scanning the object to be measured with line light (light cutting line), the object to be measured itself is linearly moved or rotated while the optical system relating to the irradiation of the line light and the image pickup thereof is fixed. Both the case where the surface of the object to be measured is moved and the case where the optical system is linearly moved or rotated along the surface of the object to be measured while the object to be measured is fixed are conceivable.
Japanese Patent Laid-Open No. 11-138654

However, a practical MPU that is allowed as a part of an inspection device (measurement device) for tire shape defects, etc., can obtain one captured image (luminance information of an image for one frame) due to restrictions on its processing capability. Then, there is a problem that it is difficult to execute the light cutting line extraction processing based on the captured image within 1/2000 [second] to 1/4000 [second]. For this reason, in the conventional inspection of tire shape defects, information on the image captured by the image sensor is stored in a large-capacity memory (such as a hard disk), and the optical cutting line based on the image captured even after the tire surface imaging process is completed. Extraction processing (image processing by MPU) must be executed, which leads to deterioration of tire production efficiency.
In addition, even when an object to be measured other than a tire, for example, a structure around a railroad track (tunnel or the like) is the object to be measured, the surface of the object to be measured is scanned and the shape is measured by an optical cutting method. In this case, if the extraction process of the light section line cannot be completed within a limited time for a large number of captured images captured at a high imaging rate or a captured image with a high resolution, the measurement efficiency is deteriorated. .
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is, for example, an imaging element (such as a CMOS sensor) that performs imaging at a high imaging rate of 2000 to 4000 frames per second, Input image information (luminance information) including an image of line light (image of light section line) irradiated on the surface of the object to be measured from an image sensor that captures an image with very high resolution. Provided is a light cutting line extraction apparatus and a light cutting line extraction method capable of executing a process of extracting a light cutting line based on a high speed (in real time) using a practical element (circuit) such as ASIC or FPGA. There is to do.

In order to achieve the above object, an optical section line extraction device according to the present invention is an image sensor (CMOS) that captures a two-dimensional image including an image of a light section line formed on the surface of a relatively moving object to be measured. The sensor is a device that inputs luminance information of each pixel in the captured image from its typical example), and extracts the image of the light section line based on the input luminance information. The following (1-1) to (1-1) 1-6) The constituent elements shown in 1-6) are provided.
(1-1) The luminance information is input in parallel for each pixel block including a pixel group obtained by further dividing the pixel group for one horizontal line in the captured image from the imaging element into the plurality of pixel groups. Information input means for executing the process of recording the luminance information and the coordinate information of the pixel in a predetermined storage means in synchronization with a clock signal of a predetermined frequency.
(1-2) Luminance information having higher luminance by comparing every two pieces of luminance information provided in a plurality of stages on the rear side of the information input means and recorded in the previous stage, and its luminance information A plurality of first luminance comparison means for executing processing for recording pixel coordinate information in a predetermined storage means in synchronization with the clock signal;
(1-3) Comparing the luminance information recorded by the first luminance comparing means at the final stage for recording the highest luminance information among the luminance information of the pixel block and the luminance information which is the previously recorded processing result Second luminance comparing means for executing processing for recording the luminance information of the higher luminance and the coordinate information of the pixel in a predetermined storage means in synchronization with the clock signal.
(1-4) Horizontal that generates a horizontal synchronization signal indicating the timing at which the luminance information of the pixel having the highest luminance is recorded in each pixel group for one horizontal line in the captured image in the second luminance comparison unit. Synchronization signal generating means.
(1-5) The luminance information recorded by the second luminance comparison unit and the coordinate information of the pixel are sequentially written in addition to the predetermined optical section line information storage unit in synchronization with the horizontal synchronization signal ( Information recording means for writing to the storage area of the storage means while sequentially changing the storage position in synchronization with the horizontal synchronizing signal.
(1-6) Luminance initializing means for initializing the luminance information recorded by the second luminance comparing means in synchronization with the horizontal synchronizing signal.
Note that “the surface of the object to be measured that moves relatively” means that the surface of the object to be measured itself is moved by linear movement or rotation of the object to be measured, and that the object to be measured is fixed. This means that the optical system for irradiating the line light and capturing the image thereof moves along the surface of the object to be measured.

An ultra-high-speed image sensor such as a CMOS sensor is a pixel group (a pixel group) in which a pixel group for one horizontal line (one line in the X-axis direction) in the captured image is further divided into a plurality of pixels. Each block is provided with a function of executing processing for outputting the luminance information in parallel (parallel output) in synchronization with a clock signal of a high frequency (for example, 20 [MHz] to 40 [MHz]).
The optical section line extraction device according to the present invention does not execute the optical section line extraction process based on the information after all the information (luminance information) of the captured image for one frame has been obtained. In synchronization with the clock signal, the luminance information is input in parallel for each of the pixel blocks that are part of the captured image, and the process of extracting the highest luminance information from the luminance information is a unit with a small calculation load. By dividing the process (the process of the first luminance comparison unit and the second luminance comparison unit) and executing them in a plurality of stages, information on the light section line extracted from the captured image for one frame ( Brightness information of the highest brightness for each horizontal line and its coordinates) are recorded in the predetermined storage means.
As a result, the optical cutting line extraction apparatus according to the present invention performs the optical cutting line extraction processing in real time with respect to the imaging rate of the imaging device, although there is a slight delay with respect to the imaging completion timing for one frame by the imaging device. Can be executed. In addition, since the operation load of the unit processing to be executed in synchronization with the clock signal can be reduced, the optical section line extraction device according to the present invention includes a practical element (circuit) such as an ASIC or FPGA. Can be realized.
In addition, since the information of the light cutting line extracted from the captured image for one frame is recorded in the predetermined storage means, if the computer that performs the shape measurement processing by the light cutting method sequentially captures the recorded information, The shape (height distribution) in the moving direction of the surface of the object to be measured can be measured by the computer.
Note that the processing of the information input means and the processing of the first brightness comparison means at the first stage for the luminance information of one set of the pixel blocks are executed in a period corresponding to two cycles of the clock signal. It is conceivable that both cases are executed continuously within a period of one cycle of the clock signal.

For example, with respect to a captured image having a resolution of 320 × 256, the image sensor separates 256 pixels for one horizontal line into 16 blocks, and the luminance information (16 Brightness information) is output in parallel in synchronization with a clock signal of 20.5 [MHz] or higher, and the optical line extracting device according to the present invention synchronizes with the clock signal of 20.5 [MHz] or higher. If the processing is executed, the light section line extraction processing can be executed in real time for an imaging rate of 4000 frames per second in theory. Further, in a practical element (circuit) such as a general ASICS or FPGA, processing is performed in synchronization with a clock signal of about 20.5 [MHz] or higher (for example, about 40 [MHz]). There is no problem.
In the case of the above example, from the end of the imaging process of the imaging device (at the start of luminance information output of the last pixel block in the image for one frame) to the completion of the recording of the light section line information for the captured image A delay time of about several clocks occurs. For example, the process of specifying one luminance information having the maximum luminance from among the 16 luminance information for the pixel block for one clock signal input to the luminance information input of the last pixel block (of the first luminance comparing means) Processing) to determine one luminance information having the maximum luminance from the luminance information of the last one line (16 pixel blocks) in the captured image for the same four clocks (for the image of the last one line) If the same processing is required for the same clock for the last process executed by the second luminance comparison means, and the same clock is required for the processing of the information recording means, a total delay time of 7 clocks is generated.

In addition, it is conceivable that the optical section line extraction device according to the present invention further includes the constituent elements shown in the following (1-7).
(1-7) Movement detection means (for example, provided on a rotating shaft of a rotating object to be measured) that detects the movement of a certain unit (relative movement has advanced by a certain unit) and outputs a detection signal thereof. Information transmission means for transmitting information written in the predetermined storage means by the information recording means to the outside in synchronization with a detection signal of the rotary encoder).
Thereby, the detection signal of the angle change detection means becomes a vertical synchronization signal in the captured image, and the information of the light section line extracted from the image for one frame in synchronization with the vertical synchronization signal is transmitted to the external device (for example, To a computer that executes a shape measurement process by a light cutting method. As a result, the shape (height distribution) in the moving direction of the surface of the object to be measured can be measured by the external device.

The present invention also provides an image sensor (CMOS) that captures a two-dimensional image including an image of a light section line formed on the surface of a relatively moving object to be measured using the light section line extraction device described above. A typical example of the sensor is that the luminance information of each pixel in the captured image is input, and an image of the optical cutting line is extracted based on the input luminance information.
That is, the light section line extraction method according to the present invention is a method for executing the following procedures (2-1) to (2-6).
(2-1) The luminance information is input in parallel for each pixel block composed of a pixel group obtained by further dividing a pixel group for one horizontal line in the captured image from the imaging element into a plurality of pixels by a predetermined information input circuit. And a luminance information input procedure for executing processing for recording the input luminance information of the pixel block and the coordinate information of the pixel in a predetermined storage means in synchronization with a clock signal having a predetermined frequency.
(2-2) All the luminance information recorded by the preceding circuit is compared with each other by each of the first comparison circuits provided in a plurality of stages on the subsequent stage side of the information input circuit. A first luminance comparison procedure for executing processing for recording luminance information of higher luminance and coordinate information of the pixel in a predetermined storage means in synchronization with the clock signal.
(2-3) The second luminance comparison circuit provided on the rear stage side of the first luminance comparison circuit in the final stage that holds the luminance information having the highest luminance among the luminance information of the pixel block, The luminance information recorded by the first luminance comparison circuit is compared with the luminance information which is the processing result previously recorded by the second luminance comparison circuit, and the luminance information having the higher luminance and the coordinate information of the pixel are obtained. A second luminance comparison procedure for executing processing for recording in a predetermined storage means in synchronization with the clock signal.
(2-4) The timing at which the luminance information of the pixel having the highest luminance is recorded in each pixel group for one horizontal line in the captured image in the second luminance comparison circuit by the predetermined signal generation circuit. A horizontal synchronization signal generation procedure for generating a horizontal synchronization signal.
(2-5) The predetermined information recording circuit synchronizes the luminance information recorded by the second luminance comparison circuit and the coordinate information of the pixel with respect to the predetermined optical section line storage means in synchronization with the horizontal synchronizing signal. Information recording procedure to write in incremental order.
(2-6) A luminance initialization procedure in which the luminance information recorded by the second luminance comparison circuit is initialized in synchronization with the horizontal synchronization signal by a predetermined luminance initialization circuit.
Further, in the light section line extraction method according to the present invention, it is also conceivable to execute the following procedure (2-7).
(2-7) Information written in the predetermined optical section line storage means by the information recording circuit in synchronism with the detection signal of the angle change detection means for detecting the movement of a predetermined unit and outputting the detection signal. Information transmission procedure for transmitting data to the outside by a predetermined information transmission circuit.
Such a light section line extraction method according to the present invention has the same effects as the light section line extraction apparatus according to the present invention described above.

  According to the present invention, for example, an imaging device (such as a CMOS sensor) that performs imaging at a high imaging rate of 2000 to 4000 frames per second or an imaging device that performs imaging at a high resolution is applied to the surface of the object to be measured. A process for inputting luminance information of a captured image including an image of irradiated line light (an image of an optical cutting line) and extracting the optical cutting line based on the luminance information is a practical element (circuit such as ASIC or FPGA). ) Can be executed at high speed (in real time).

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a diagram showing a schematic configuration of a shape measuring device W provided with the light section line extraction device X according to the embodiment of the present invention, and FIG. 2 is a third order of a light source and a camera in a sensor unit provided in the shape measuring device W. FIG. 3 is a schematic diagram showing the original arrangement, FIG. 3 is a block diagram showing a schematic configuration of the optical cutting line extraction device X and a device that exchanges signals with the optical cutting line extraction device X, and FIG. 4 shows an image processing circuit of the optical cutting line extraction device X FIG. 5 is a schematic block diagram, and FIG. 5 is a diagram schematically showing a correspondence relationship between a captured image and data detected by the optical cutting line extraction apparatus X.

First, with reference to FIG. 1 and FIG. 2, the configuration of the entire shape measuring device W and the sensor unit including the light section line extraction device X according to the embodiment of the present invention will be described.
The shape measuring device W is an image sensor provided in the camera 20 (the camera 20 includes an image of line light (slit light) irradiated on the surface of the rotating tire 1 (an example of an object to be measured). This is an apparatus for detecting the surface shape of the tire 1 by taking an image with a CMOS sensor 21) and performing shape detection by a light cutting method based on the taken image. As the tire 1 rotates around its rotation axis 1a, the surface of the tire 1 moves relative to the line light and the camera.
In addition, the optical cutting line extraction device X included in the shape measuring device W includes an image sensor that picks up a two-dimensional image including an image of the optical cutting line formed on the surface of the moving tire 1. This is an apparatus for executing light cutting line extraction processing for inputting luminance data and extracting an image of a light cutting line (detecting coordinates of the image of the light cutting line) based on the input luminance data.
As shown in FIG. 1, the shape measuring device W includes a tire rotating machine 2, a sensor unit 3, a unit driving device 4, an encoder 5, an optical cutting line extraction device X, a host computer 7, and the like.
The tire rotating machine 2 is a rotating device such as a motor that rotates the tire 1 that is the object of shape measurement about the rotation shaft 1g. For example, the tire rotating machine 2 rotates the tire 1 at a rotation speed of 60 rpm. As a result, the shape measuring device W detects the surface shape of the entire circumference range of the tread surface and the sidewall surface of the tire 1 by the sensor unit 3 to be described later during one second in which the tire 1 is rotated once.
The sensor unit 3 includes a light source 10 that irradiates the surface of the rotating tire 1 with line light and a camera 20 that captures an image of the light cutting line Ls (line light image) on the surface of the tire 1. It is. In the present embodiment, two sensor units 3a and 3c used for measuring the shape of each of the two sidewall surfaces of the tire 1 and one sensor unit 3b used for measuring the shape of the tread surface of the tire 1 are combined. Two sensor units 3 are provided.

The unit driving device 4 is a device for supporting each sensor unit 3 movably by using a driving device such as a servo motor as a driving source, and positioning the position of each sensor unit 3 with respect to the tire 1. The unit driving device 4 moves each sensor unit 3 before the tire 1 is attached to or detached from the tire rotating machine 2 according to an operation on a predetermined operation unit or a control command from an external device. After a new tire 1 is mounted on the tire rotating machine 2, the sensor unit 3 is positioned at a predetermined inspection position close to the tire 1.
The encoder 5 is provided on the rotating shaft of the tire rotating machine 2, detects that the rotation angle of the rotating shaft, that is, the rotation angle of the tire 1 has changed by a predetermined unit angle, and detects the detection signal (pulse Signal) as a reset signal RESET described later (an example of the angle change detection means), and the detection signal (reset signal RESET) is used to control the imaging timing of the camera provided in the sensor unit 3 and the optical cutting line. It is used for controlling the data transfer timing from the extracting device X to the host computer 7. The encoder 5 is an example of the movement detecting unit that detects a certain unit of movement of the surface of the tire 1 and outputs a detection signal thereof.

Further, as shown in FIG. 2, the sensor unit 3 includes a light projecting device 10 that outputs line light (slit light) and a camera 20. FIG. 2 shows an example in which the measurement target surface is the sidewall surface of the tire 1.
As shown in FIG. 2, the X-axis direction (horizontal line direction) in the coordinate system of the captured image of the camera 20 and the moving direction R of the surface of the tire 1 due to rotation are parallel, and the Y-axis direction in the coordinate system of the captured image and the tire The light projecting device 10 and the camera 20 are arranged so that the direction perpendicular to the moving direction on one surface is parallel.
Further, the direction of the output light (line light) is set so that the image of the light cutting line Ls formed on the surface of the tire 1 extends in the Y-axis direction in the coordinate system of the captured image. Has been. The above is the same whether the measurement target surface is the sidewall surface of the tire 1 or the tread surface.
That is, in the measurement of the sidewall surface of the tire 1, the direction orthogonal to both the radial direction of the tire 1 (the direction of the normal to the rotating shaft 1g of the tire 1) and the direction of the rotating shaft 1g of the tire 1 is the coordinate system. Parallel to the X-axis direction, the radial direction of the tire 1 is parallel to the Y-axis direction of the coordinate system, and the light cutting line Ls extends in the radial direction of the tire 1.
Further, in the measurement of the tread surface of the tire 1, the direction of the rotation axis 1g of the tire 1 is parallel to the Y-axis direction of the coordinate system, and the tangential direction of the outer circumference circle of the tire 1 is parallel to the X-axis direction of the coordinate system. In addition, the light cutting line Ls is formed extending in the direction of the rotation axis 1g of the tire 1.

Next, with reference to the block diagram shown in FIG. 3, the relationship between the optical section line extraction device X and the device that performs signal exchange will be described.
As shown in FIG. 3, the optical section line extraction device X includes an image processing circuit 61, an SDRAM 62, and a parallel I / O interface 63 (denoted as PIO I / F in FIG. 3).
The image processing circuit 61 is a circuit realized by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like, which is a programmable LSI, and is a circuit that mainly performs light cutting line extraction processing.
The SDRAM 62 is a high-speed memory that temporarily stores the data of the light section line that is the processing result of the image processing circuit 61. Note that this memory may be another high-speed memory such as SRAM.
The parallel I / O interface 63 performs high-speed transfer to the host computer 7 by parallel transfer of the data of the optical section line for each captured image of one frame stored (recorded) in the SDRAM 62. It is a circuit to transfer. The host computer 7 includes a parallel I / O interface 71 that transmits data to and from the parallel I / O interface 63 on the optical section line extraction device X side, and through this, the data of the optical section line is stored in the main memory. Into.
Then, the host computer 7 executes shape measurement processing by the light cutting method based on the data of the light cutting line acquired through the parallel I / O interface 71. For example, the host computer 7 obtains the shape (height distribution) in the rotational direction of the surface of the tire 1 based on the acquired data of the optical cutting line, and displays the shape on a display device (not shown). By determining whether or not a predetermined pass condition (or fail condition) is satisfied, a process of determining the presence or absence of a tire shape defect is executed.
The host computer 7 processes the acquired data of the light section line as data in a region where the light section line does not exist if the brightness level of the brightness data is less than a predetermined level.

The camera 20 also includes an objective lens (not shown), a CMOS sensor 21 that is an imaging device that captures an image formed by the objective lens, and an analog signal representing imaging data output from the CMOS sensor 21 as a digital signal. And an A / D converter 22 (referred to as ADC in FIG. 3).
The CMOS sensor 21 synchronizes with a clock signal CLK having a high frequency (for example, 4000 [Hz] or more) for one frame of the captured image for one horizontal line (for one line in the X-axis direction). The luminance data is output in parallel (parallel output) for each of the pixel blocks composed of pixel groups into which the pixel group is further divided. The luminance data Dbk for each pixel block is transmitted to the image processing circuit 61 in the light section line extraction device X through the A / D converter 22. At this time, when the CMOS sensor 21 outputs the luminance data Dbk, the block number data BN indicating the number of pixel blocks in the image for one frame is simultaneously displayed (luminance data Dbk). In parallel). This block number data BN is information indicating the position of each pixel block in an image for one frame, and is also transmitted to the image processing circuit 61 in the light section line extraction device X.
The clock signal CLK is supplied from a predetermined oscillation circuit 30 provided inside or outside the optical section line extraction device X.
Further, the CMOS sensor 21 captures an image for one frame in synchronization with the detection signal (the reset signal RESET) of the encoder 5. For example, the CMOS sensor 21 captures an image for one frame every time the encoder 5 detects that the tire 1 rotating at a speed of 60 rpm has rotated by 0.09 ° (= 360 ° / 4000). Imaging is performed at an imaging rate of 4000 frames per second.
In the present embodiment, the CMOS sensor 21 has, for a captured image with a resolution of 320 × 256, for each pixel block (16 pixel groups) when 256 pixels for one horizontal line are divided into 16 blocks. The luminance data (16 pieces of luminance data D00 to D0f) is output in parallel in synchronization with the clock signal CLK of 40 [MHz]. Note that the frequency of the clock signal CLK of 40 [MHz] is a frequency that has a sufficient margin with respect to the theoretical required frequency of 20.5 [MHz] that can correspond to an imaging rate of 4000 frames per second. If the resolution of the captured image is 256 × 256, the frequency of the clock signal CLK may be about 20 [MHz].
Further, the CMOS sensor 21 outputs the luminance data of the pixel group for one horizontal line (one line in the X-axis direction) in the captured image, that is, the luminance of the last pixel block in the pixel group for one horizontal line. Each time the data Dbk is output, the line completion signal END-LINE is output. The clock signal CLK and the line completion signal END-LINE are also input to the image processing circuit 61 in the optical section line extraction device X.
It is also conceivable to employ a CCD or the like as an image sensor that replaces the CMOS sensor 21.
The detection signal of the change in the rotation angle of the tire 1 by the encoder 5 is input to the image processing circuit 61 and the parallel I / O interface 63 in the optical cutting line extraction device X as the reset signal RESET.

FIG. 5 shows the correspondence between the captured image of the tire 1 by the CMOS sensor 21 (the lower diagram in FIG. 5) and the detection data (Xp, Yi, Kp) by the optical cutting line extraction device X (the upper diagram in FIG. 5). It is the figure which represented the relationship typically. In FIG. 5B, for the sake of convenience, the image of the light cutting line Ls in the picked-up image is shown in black and the background in white, but the actual picked-up image is the luminance of the image portion of the light cutting line Ls. This is an image with high brightness and low brightness in the background area.
The image processing circuit 61 sequentially inputs the luminance data Dbk of the pixel block, and every time the input data becomes the data for one horizontal line, the luminance data of the pixel for the horizontal one line after a certain delay time. Brightness data (maximum in-line brightness data Kp) and coordinate information that can specify the X coordinate (Xp) and Y coordinate (Yi) of the pixel position corresponding to the in-line maximum brightness data Kp. Recorded in the SDRAM 62 as the extraction data of the light section line. However, in this embodiment, the Y coordinate (Yi) is specified by the arrangement order of the data Kp in the data string of the in-line maximum luminance data Kp, and individual data representing each Y coordinate (Yi) is directly Is not recorded in the SDRAM 62.

Next, the configuration and processing of the image processing circuit 61 will be described with reference to the block diagram shown in FIG.
In the image processing circuit 61, a circuit for performing simple data processing and processing for recording the processing result in a register (hereinafter referred to as a single process circuit) is connected in a plurality of stages, and each single process circuit is output from the oscillation circuit 30. This is a circuit for executing the processes in charge of each in parallel in synchronization with the clock signal CLK (every time a pulse signal is input). Here, the single-stage circuit at the first stage inputs the luminance data Dbk of the pixel block from the CMOS sensor 21 in synchronization with the clock signal CLK, and inputs the input data to a predetermined register (for example, one stage after the stage). Register in the single process circuit), and the second and subsequent single process circuits are based on the data recorded in the register by the single process circuit of the previous stage and the result of the processing. Is recorded in a register (for example, a register included in a single process circuit at the next stage).

More specifically, the single-stage circuit 610 at the first stage inputs the luminance data Dbk (D00 to D0f) and the block number data BN in parallel for each pixel block from the CMOS sensor 21 and inputs them. This is a circuit that executes the process of recording the luminance data Dbk and block number data BN of the pixel block in a predetermined input buffer in synchronization with the clock signal CLK (an example of the information input means and the information input circuit). Here, the block number data BN is information indicating the position (coordinates) in the captured image of the pixel block corresponding to the input data, and the storage position (register address) of the input luminance data D00 to D0f is the pixel. Since it corresponds to the position (order) of each pixel in the block, the single-stage circuit 610 in the first stage records the coordinate data of the pixels in the pixel block together with the luminance data Dbk of the input pixel block in the register. It has become.
The single-step circuit 610 in the first stage initializes the luminance data D00 to D0f already recorded in the input buffer in synchronization with the reset signal RSET that is an angle change detection signal of the encoder 5 (minimum luminance value 0). Update).
As described above, the luminance data Dbk is luminance data of a pixel block including a pixel group obtained by further dividing the pixel group for one horizontal line in the captured image of the CMOS sensor 21 into a plurality of pixels. The example shown in FIG. 4 is an example in which luminance data of 16 pixel blocks (16 pieces of luminance data D00 to D0f) are input in parallel. Also, it is not always necessary to initialize the luminance data in accordance with the reset signal RESET in the first stage single process circuit 610.

The single-stage circuits 611a to 611d of the second stage to the fifth stage are provided to be connected to a plurality of stages (here, four stages) on the rear side of the single-stage circuit 610 of the first stage for data input. All luminance data recorded by the single-stage circuit in the previous stage is compared every two, and the higher luminance data and the coordinate information of the pixel are registered in a predetermined register (in this case, the single-stage in the next stage) A plurality of (in this case, four) data comparison circuits (in this case, the first luminance comparison circuit and the first luminance comparison circuit) that execute the process of recording in the register included in the circuit in synchronization with the clock signal CLK. One case).
That is, the single-stage circuit 611a in the second stage compares all the luminance data D00 to D0f recorded by the single-stage circuit 610 in the first stage in synchronization with the clock signal CLK, and the luminance is high. The other luminance data D10 to D17 and the coordinate information BN and C10 to C17 indicating the positions (coordinates) of the pixels corresponding to the luminance data D10 to D17 are recorded in the register provided in the next single-stage circuit. Here, the coordinate information includes the block number data BN and the in-block pixel number data C10 to C17 representing the position (order) in the pixel block of one of the two pixels determined to have high luminance. And are included.
Further, the single-stage circuit 611b at the third stage compares all the luminance data D10 to D07 recorded by the single-stage circuit 611a at the second stage in synchronism with the clock signal CLK, and the luminance is high. The other luminance data D20 to D23 and the coordinate information BN and C20 to C23 indicating the position (coordinates) of the pixel corresponding to the luminance data D20 to D23 are recorded in the register provided in the next single-stage circuit. Here, the coordinate information includes the block number data BN and the pixel number data C20 to C23 in the block indicating the position (order) in the pixel block of one of the two pixels determined to have high luminance. And are included.
Thereafter, the fourth-stage single process circuit 611c and the fifth-stage single process circuit 611d also execute the same processing as the third-stage single process circuit 611b in synchronization with the clock signal CLK.
As a result, the single-stage circuit 611d at the final stage among the single-stage circuits 611a to 611d at the second to fifth stages has the luminance data D40 having the highest luminance among the luminance data D00 to D0f of one pixel block. The coordinate information BN, C40 is a circuit that records in a register (here, a register included in the sixth stage single process circuit 612a).
That is, when the pixel block is composed of 2 ^N pixels (where N is an integer equal to or greater than 2), the image processing circuit 61 is connected to each of the second-stage to fifth-stage single process circuits 611a to 611d. A corresponding single process circuit includes a circuit connected in N stages.
Note that the single-step circuit 610 in the first stage simply performs a light process (a process that does not involve an operation) that simply inputs the luminance data D00 to D0f of the pixel block. In addition, both the processing of the single-step circuit 610 at the first stage and the processing of the single-step circuit 611a at the second stage may be performed.

The sixth and seventh stage single process circuit 612, which includes the sixth stage single process circuit 612a and the seventh stage single process circuit 612b, has five stages of data having the highest luminance among the luminance data D00 to D0f of the pixel block. Luminance data D40 recorded by the single-step circuit 611d of the eye (corresponding to the first luminance comparison means in the final stage), and luminance data which is the processing result previously recorded in the register by the single-step circuit 612 of the sixth stage D50 ′ is compared with D50 ′, and the process of recording the luminance data D50 having higher luminance and the coordinate information ADDR of the pixel in a predetermined register (the register and output register 61y provided in the seventh stage single process circuit 612b) It is a circuit that executes in synchronization with the signal CLK (an example of the second luminance comparison means and the second luminance comparison circuit).
More specifically, the sixth stage single process circuit 612a synchronizes with the clock signal CLK and the luminance data D40 recorded by the fifth stage single process circuit 611d and the sixth stage single process circuit 612a. Is compared with the luminance data D50 ′ which is the processing result previously recorded in the register of the single-step circuit 612b of the seventh stage, and the luminance data D50 having the higher luminance and the coordinate information ADDR of the pixel are compared. It records in the register | resistor with which the process circuit 612b is equipped. Here, the coordinate information ADDR is information obtained by combining the block number data BN and the in-block pixel number data C40. It should be noted that the sixth stage single process circuit 612a, when the luminance data D40 recorded by the fifth stage single process circuit 611d has a higher luminance, is recorded by the fifth stage single process circuit 611d. The coordinate information ADDR combining the block number data BN and the in-block pixel number data C40 is recorded in the register. Otherwise, the coordinate information ADDR already recorded in the register of the single-step circuit 612b at the seventh stage is the same. Keep content as it is (including overwriting the same content).

In addition, the seventh stage single process circuit 612b synchronizes with the clock signal CLK, the luminance data 50 recorded by the sixth stage single process circuit 612a and the coordinate information ADDR of the pixel thereof in a predetermined data format. This is a circuit that records the data in the output register 61y in a state of being shaped into a data (for example, a state in which invalid data is added and the data length is converted to a predetermined data length).
Further, the seventh stage single process circuit 612b synchronizes with a horizontal synchronization signal Hsync described later, and the luminance data D50 already recorded in the register of the seventh stage single process circuit 612b and the coordinate information ADDR of the pixel. (Information recorded by the sixth and seventh stage single process circuit 612) is initialized (updated to the lowest luminance value 0) (an example of the luminance initialization means and the luminance initialization circuit).
Further, the single-stage circuits 610, 611a to 611d, 612a, 612b of the second to seventh stages are the luminances already recorded in the registers in synchronization with the reset signal RSET which is an angle change detection signal of the encoder 5. Data D10 to D17, D20 to D23, D30, D31, D40, and D50 are initialized (updated to the lowest luminance value 0).
The single-stage circuits 610, 611a to 611d, 612a, 612b in the second to seventh stages are examples of the luminance initialization unit and the luminance initialization circuit.
All the pixel blocks input after the initial state (data initialized state) is obtained by the processing of the single-step circuits 610, 611a to 611d, 612a, 612b of the first to seventh stages shown above. , The luminance data D50 of the pixel having the highest luminance and the coordinate information ADRESS of the pixel are recorded in the output register 61y.

By the way, in the example of the circuit shown in FIG. 4, the luminance data D00 to D0f of the last pixel block in the pixel group for one horizontal line in the captured image is converted into the image processing circuit 61 by the single process circuit 610 in the first stage. The luminance data Dmax of the pixel having the highest luminance in all the pixels for one horizontal line from the time when the line completion signal END-LIN is input and the coordinate information Amax of the pixel. Before the recording process to the output register 61y (the process by the sixth stage single process circuit 614) is started, a step (time) of 6 clocks is required in the clock signal CLK. Therefore, a signal obtained by delaying (shifting) the line completion signal END-LIN by 6 clocks in the clock signal CLK is transferred to each of the pixel groups corresponding to one horizontal line in the captured image by the sixth and seventh stage single process circuit 612. The signal indicating the timing when the luminance data of the pixel having the highest luminance is recorded in the output register 61y (recording is completed), that is, the horizontal synchronization signal Hsync when the recording data of the output register 61y is used as a reference.
The image processing circuit 61 includes a delay circuit 614 that generates a horizontal synchronization signal Hsync by delaying (shifting) the line completion signal END-LIN by 6 clocks in the clock signal CLK (the horizontal synchronization signal Hsync). An example of signal generation means and the horizontal synchronization signal generation circuit).
As described above, when both the first stage single process circuit 610 and the second stage single process circuit 611a are processed within one cycle of the clock signal CLK, the delay circuit 614 The line completion signal END-LIN may be delayed (shifted) by 5 clocks in the clock signal CLK.

As described above, the pixel block inputted after the initial state (data initialized state) is obtained by the processing of the single-step circuits 610, 611a to 611d, 612a, 612b of the first to seventh stages. For all, the luminance data D50 of the pixel with the highest luminance and the coordinate information ADRESS of the pixel are recorded in the output register 61y.
In addition, the seventh stage single process circuit 612b synchronizes with the horizontal synchronization signal Hsync, and the brightness data D50 and the pixel coordinate information ADDR of the pixel already recorded in the register included in the seventh stage single process circuit 612b are initialized. Therefore, when the horizontal synchronization signal Hsync is generated, the output register 61y has the luminance data of the pixel having the highest luminance in the pixel group for one horizontal line and its pixel. The coordinate information is recorded (stored).

The image processing circuit 61 includes a gate circuit 613 that is an eighth stage single-process circuit that executes processing for writing the data recorded in the output register 61y into the SDRAM 62 in synchronization with the horizontal synchronization signal Hsync. Yes.
The gate circuit 613 sends the luminance data D50 recorded in the output register 61y and the coordinate information ADDR of the pixel to the horizontal synchronization signal Hsync for the storage area of the SDRAM 62 (an example of the predetermined optical section line information storage means). In this manner, a process of writing while changing the storage position sequentially (that is, writing sequentially and additionally) is executed (an example of the information recording means and the information recording circuit).
As a result of the processing of the image processing circuit 61 described above, a captured image for one frame is generated after the reset signal RESET, which is an angle change detection signal of the encoder 5, is generated and until the next reset signal RESET is generated. The data of the light cutting line is accumulated (recorded). Here, the data of the light section line are the data D50 representing the luminance value Kp of the pixel having the highest luminance for each horizontal line (for each position Yi in the Y coordinate direction) and the coordinates representing the coordinate Xp of the pixel. Data including information ADDR.
The parallel I / O interface 63 accumulates (records) the data of the optical cutting line for the captured image for one frame in the SDRAM 62 in synchronization with the reset signal RESET which is an angle change detection signal of the encoder 5. Each time the data written to the SDRAM 62 by the gate circuit 613 (data of the optical section line) is transferred at high speed to the external host computer 7 by parallel transfer (an example of the information transmission means and the information transmission circuit). ).

The optical section line extraction device X described above does not execute the light section line extraction process based on the information after all the information (luminance information) of the captured image for one frame is obtained, but has a high frequency. The process of inputting the luminance data Dbk in parallel for each of the pixel blocks that are part of the captured image in synchronization with the clock signal CLK, and further extracting the highest luminance data from the luminance data Dbk. Each single-process circuit is divided into processes with a small calculation load, and these processes are executed in a series of stages, whereby the data of the light section line extracted from the captured image for one frame (the maximum luminance for each horizontal line) Are recorded in the SDRAM 62.
As a result, the optical section line extraction device X executes the optical section line extraction processing in real time with respect to the imaging rate of the CMOS sensor 21, although there is a slight delay with respect to the timing of completing the imaging for one frame by the CMOS sensor 21. can do. In addition, since the calculation load of the processing to be executed in synchronization with the clock signal CLK (processing of each single process circuit) can be reduced, the optical disconnection line extraction device according to the present invention is practical for ASIC, FPGA, and the like. This can be realized using a simple element (circuit).
In addition, the light section line extraction device X inputs the luminance data for each relatively small number of pixel groups (pixel blocks), and sequentially leaves only the data with the higher luminance by comparing two data (recorded in a register). Therefore, it is only necessary to provide a relatively small capacity memory (register), which can be realized by a simple device (circuit) configuration.
In addition, the optical cutting line extraction device X has a high resolution of the picked-up image, so even if the number of luminance data input per time is large, the optical cutting line extraction apparatus X is delayed even though there is a delay with respect to the image pickup completion timing for one frame. Processing can be performed in real time for continuous imaging.

In addition, the data of the optical section line is recorded in the SDRAM 62 almost in synchronization with the imaging rate (for example, 1/4000 [second]) of the CMOS sensor 21 and transferred to the host computer 7. When a practical computer (personal computer or the like) is adopted as the host computer 7, the host computer 7 acquires the data of the optical cutting line through the parallel I / O interface 71, and based on the data, the tire surface The time required for measuring the shape (height distribution) in the rotation direction and determining the pass / fail of the tire 1 based on the measurement data is about 1/4000 [second].
Therefore, if the optical section line extraction device X is used, in the tire shape defect inspection process, the determination result of the presence / absence of the shape result is obtained in real time with respect to the accelerated imaging process (for example, 1 second) of the surface of the tire 1 be able to.

The optical section line extraction device X described above has obtained an example in which the line completion signal END-LINE is acquired from the CMOS sensor 21 and the horizontal synchronization signal Hsync is generated based on the line completion signal END-LINE. The horizontal synchronization signal Hsync may be generated by other methods.
For example, the counter that counts the number of clock signals CLK input after the reset signal RSET is input to the image processing circuit 61 and generates the horizontal synchronization signal Hsync when the count reaches a predetermined number. It is also possible to provide a circuit.
Similarly, it is conceivable to provide the image processing circuit 61 with a circuit for generating the block number data BN. As such a circuit, for example, each time the reset signal RSET is input, the block number data BN is initialized, and thereafter, the number of clock signals CLK input is counted and the count number becomes a predetermined number. In addition, a circuit for generating the block number data BN by counting up the value of the block number data BN can be considered.
Further, in the image processing circuit 61 shown in FIG. 4, the gate circuit 613 is a circuit for writing the data recorded in the register included in the seventh stage single process circuit 612b to the SDRAM 62, and the output register 61y and its output register 61y. A configuration in which the recording process is omitted is also conceivable. In this case, however, the delay clock number of the line completion signal END-LINE by the delay circuit 614 is 5 clocks.

In the above-described embodiment, the rotating tire 1 is an object to be measured, and the optical cutting line extraction device X that extracts the optical cutting line formed on the tire surface that moves by the rotation is shown. Thus, it is also possible to measure the shape of the surface of another moving object to be measured.
For example, if the sensor unit 3 is arranged to face the measurement target surface of the object to be moved that moves in a linear direction, and the optical cutting line extraction device X performs the same processing as the processing in the above-described embodiment, Extraction processing of the light cutting line formed on the surface of the object to be measured can be executed at high speed.
Further, as shown in the embodiment, in addition to a device configuration that scans the surface of the object to be measured by moving the surface of the object to be measured such as the tire 1 while the sensor unit 3 is fixed, for example, a railway Move the sensor unit 3 along the surface of the object to be measured (linear movement or rotational movement) while the object to be measured is fixed as in the case where the structure around the track (tunnel, etc.) is the object to be measured. It is also possible to consider a device configuration that scans the surface of the object to be measured.

  The present invention can be used for an optical section line extraction device.

The figure showing schematic structure of the shape measuring apparatus W provided with the optical cutting line extraction apparatus X which concerns on embodiment of this invention. The figure which represented typically the three-dimensional arrangement | positioning of the light source and camera in a sensor unit with which the shape measuring apparatus W is provided. The block diagram showing schematic structure of the apparatus which performs optical section line extraction apparatus X and this and signal transmission / reception. 3 is a schematic block diagram of an image processing circuit provided in the light section line extraction device X. FIG. The figure which represented typically the correspondence of a captured image and the detection data by the optical cutting line extraction apparatus X. FIG.

Explanation of symbols

W: Shape measuring device 1: Tire 2: Tire rotating machine 3: Sensor unit 4: Unit drive device 5: Encoder 6: Image processing device 10: Projection device 11, 12, 13: Line light source 20: Camera 21: Image sensor 22: Camera lens Ls1, Ls2, Ls3: Optical cutting line

Claims (8)

Input brightness information of each pixel in the captured image from an image sensor that captures a two-dimensional image including an image of a light section line formed on the surface of the object to be moved relatively, and based on the input brightness information A light cutting line extraction device for extracting an image of the light cutting line,
Luminance information is input in parallel for each pixel block consisting of a pixel group obtained by further dividing a pixel group corresponding to one horizontal line in the captured image from the image sensor, and the input luminance information of the pixel block and its Information input means for executing processing for recording pixel coordinate information in a predetermined storage means in synchronization with a clock signal having a predetermined frequency;
The information input means is provided in a plurality of stages on the rear side of the information input means, and the brightness information of the higher brightness and the coordinate information of the pixel are compared by comparing every two pieces of brightness information recorded in the previous stage. A plurality of first luminance comparison means for executing processing for recording in a predetermined storage means in synchronization with the clock signal;
Comparing the luminance information recorded by the first luminance comparison means at the last stage for recording the highest luminance information among the luminance information of the pixel block in the predetermined storage means and the luminance information as the processing result recorded last time A second luminance comparing means for executing processing for recording the luminance information of the higher luminance and the coordinate information of the pixel in a predetermined storage means in synchronization with the clock signal;
A horizontal sync signal generating means for generating a horizontal sync signal representing the timing at which the brightness information of the pixel having the highest brightness is recorded in each pixel group for one horizontal line in the captured image in the second brightness comparing means; ,
Information recording means for sequentially writing the luminance information recorded by the second luminance comparing means and the coordinate information of the pixel in a predetermined optical section line information storage means in synchronization with the horizontal synchronization signal;
Brightness initialization means for initializing the brightness information recorded by the second brightness comparison means in synchronization with the horizontal synchronization signal;
An optical section line extraction device comprising:   Information written in the predetermined optical section line information storage means is transmitted to the outside by the information recording means in synchronization with a detection signal of a movement detection means for detecting the movement of a certain unit and outputting the detection signal. The light section line extraction device according to claim 1, further comprising an information transmission means.   The optical section line extraction device according to claim 1, wherein the image sensor is a CMOS sensor.   The optical section line extraction device according to claim 1, wherein the object to be measured is a rotating tire. Input brightness information of each pixel in the captured image from an image sensor that captures a two-dimensional image including an image of a light section line formed on the surface of the object to be moved relatively, and based on the input brightness information An optical cutting line extraction method for executing processing for extracting an image of the optical cutting line,
The predetermined information input circuit inputs the luminance information in parallel for each pixel block composed of pixel groups obtained by further dividing a pixel group for one horizontal line in the captured image from the image sensor into the captured image. A luminance information input procedure for executing processing for recording the luminance information of the pixel block and the coordinate information of the pixel in a predetermined storage means in synchronization with a clock signal of a predetermined frequency;
Each of the first comparison circuits arranged in a plurality of stages on the rear side of the information input circuit compares all the luminance information recorded by the previous circuit every two, and the higher the luminance is. A first luminance comparison procedure for executing processing for recording luminance information and coordinate information of the pixel in a predetermined storage means in synchronization with the clock signal;
The first luminance comparison in the final stage is performed by the second luminance comparison circuit provided on the rear stage side of the first luminance comparison circuit in the final stage for recording the highest luminance information among the luminance information of the pixel block. The luminance information recorded by the circuit is compared with the luminance information which is the processing result previously recorded by the second luminance comparison circuit, and the luminance information having the higher luminance and the coordinate information of the pixel are recorded in a predetermined storage means. A second luminance comparison procedure for performing processing to be performed in synchronization with the clock signal;
A predetermined signal generation circuit generates a horizontal synchronization signal indicating the timing at which the luminance information of the pixel having the highest luminance is recorded in each pixel group for one horizontal line in the captured image in the second luminance comparison circuit. Horizontal sync signal generation procedure to
The luminance information recorded by the second luminance comparison circuit and the coordinate information of the pixel are sequentially added to a predetermined light section line information storage means in synchronization with the horizontal synchronizing signal by a predetermined information recording circuit. Information recording procedure to write,
A luminance initialization procedure for initializing the luminance information recorded by the second luminance comparison circuit in synchronization with the horizontal synchronization signal by a predetermined luminance initialization circuit;
An optical section line extraction method comprising:   The information written in the predetermined optical section line information storage means by the information recording circuit is transmitted in predetermined information in synchronization with the detection signal of the movement detection means for detecting the movement in a certain unit and outputting the detection signal. 6. The method for extracting an optical section line according to claim 5, further comprising executing an information transmission procedure for transmission to the outside by a circuit.   The optical section line extraction method according to claim 5, wherein the image sensor is a CMOS sensor.   The optical section line extraction method according to claim 5, wherein the object to be measured is a rotating tire.