JP4858098B2 - Vision sensor and lighting setting method - Google Patents

Description

  The present invention relates to a visual sensor and a lighting setting method, and more particularly to a visual sensor and a lighting setting method for selecting an optimal lighting pattern from a plurality of lighting patterns.

2. Description of the Related Art A visual sensor has been developed that takes an image of a measurement object such as an industrial product with a camera and measures the appearance of the measurement object. For example, Patent Literatures 1 to 4 disclose a visual sensor or a device related to the visual sensor.
JP 2006-19901 A JP 2001-101416 A JP-A-10-136272 Japanese Patent Laid-Open No. 10-320538

  By the way, in order to perform accurate measurement, it is necessary to set an appropriate illumination pattern according to the measurement object. As an element of the illumination pattern, for example, the direction and intensity of light irradiated on the measurement object can be considered. These elements are appropriately adjusted according to the measurement object itself and the surrounding environment, and know-how and proficiency are required to set an appropriate illumination pattern.

  Therefore, an object of the present invention is to provide a visual sensor and an illumination setting method capable of easily setting an optimal illumination pattern.

  In order to solve the above problems, a visual sensor according to an aspect of the present invention includes a plurality of illumination blocks, and determines whether or not each illumination block is turned on and the intensity of irradiation light of each illumination block (m is 3). The above-mentioned natural number) illumination unit that irradiates light to the measurement object based on the types of illumination patterns, and m first objects by imaging the measurement objects irradiated with light based on the m types of illumination patterns. An imaging unit for acquiring a next candidate image; brightness of a plurality of pixels in each of the acquired m first candidate images; and a plurality of pixels in each of the acquired m first candidate images. Based on at least one of the m evaluation values calculated based on the brightness, n (n is a natural number satisfying 2 ≦ n <m) secondary images out of the m primary candidate images. A control unit for selecting candidate images; A display unit that displays the selected n secondary candidate images; and an operation unit that recognizes an image selected by the user from the displayed n secondary candidate images. The measurement object is irradiated with light based on the illumination pattern corresponding to the image selected by.

  Preferably, the control unit stores m types of lighting patterns that determine whether or not each lighting block is lit, the lighting unit irradiates the measurement object with light based on the m types of lighting patterns, and the imaging unit includes: Each of the measurement objects irradiated with light is imaged based on m kinds of lighting patterns to acquire m images, and the control unit brightness of the plurality of pixels in each of the acquired m images. Based on the above, a combination of each of the m types of lighting patterns and the intensity of the irradiation light of each illumination block is determined as m types of illumination patterns.

  Preferably, the control unit calculates the contrast of each of the m primary candidate images as an evaluation value based on the brightness of the plurality of pixels in each of the acquired m primary candidate images.

  More preferably, the control unit calculates a variance value of brightness of a plurality of pixels in each of the acquired m primary candidate images as an evaluation value of each of the m primary candidate images.

  Preferably, the plurality of illumination blocks irradiate the measurement object with light from different directions, and the control unit applies m types of light so that the measurement object is irradiated with light from different directions in m types of illumination patterns. Determine the lighting pattern.

  Preferably, the operation unit is configured such that after the user selects an image, the user changes the illumination pattern corresponding to the image selected by the user, whether or not each lighting block is turned on or the intensity of irradiation light of each lighting block is changed. Recognizing the pattern, the illumination unit irradiates the measurement object with light based on the illumination pattern changed by the user.

  In order to solve the above-described problem, an illumination setting method according to an aspect of the present invention is a m (m is a natural number of 3 or more) that determines whether or not a plurality of illumination blocks are turned on and the intensity of irradiation light of the plurality of illumination blocks. ) A first illumination step for irradiating the measurement object with light based on the types of illumination patterns, and m first images by imaging each of the measurement objects irradiated with light based on the m types of illumination patterns. An imaging step for acquiring a next candidate image; brightness of a plurality of pixels in each of the acquired m first candidate images; and a plurality of pixels in each of the acquired m first candidate images. Based on at least one of the m evaluation values calculated based on the brightness, n (n is a natural number satisfying 2 ≦ n <m) secondary images out of the m primary candidate images. Images for selecting candidate images A selection step, a display step for displaying the selected n secondary candidate images, an operation step for recognizing an image selected by the user from the displayed n secondary candidate images, and a user selection A second illumination step of irradiating the measurement object with light based on the illumination pattern corresponding to the image.

  According to the present invention, an optimal illumination pattern can be easily set.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Configuration and basic operation]
FIG. 1 is a perspective view showing a configuration of a visual sensor according to an embodiment of the present invention.

  With reference to FIG. 1, the visual sensor 201 includes a controller 101 and a camera 102. The camera 102 includes an illumination unit 51 and an imaging unit 52. The illumination unit 51 and the imaging unit 52 are integrated. The illumination unit 51 may be configured not to be integrated with the imaging unit 52 but to be disposed outside the camera 102. The controller 101 includes an LCD (Liquid Crystal Display) touch panel 4, a camera connector 8, an external input / output connector 11, and an operation unit cover 14.

  The controller 101 controls the illumination unit 51 to irradiate the measurement target with light in synchronization with a measurement timing signal received from a transmission sensor (not shown) indicating the presence of the measurement target, and causes the imaging unit 52 to measure the measurement target. Is controlled to image. Then, the imaging unit 52 outputs the captured image data to the controller 101.

  The controller 101 inputs measurement parameters, measurement timing, and the like via a setting button 6, an LCD touch panel 4, and a console connector 9 which will be described later.

FIG. 2 is a functional block diagram showing the configuration of the visual sensor according to the embodiment of the present invention.
Referring to FIG. 2, the controller 101 includes a central control circuit (control unit) 61, an LCD controller 3, an LCD touch panel (display unit and operation unit) 4, a touch panel controller 5, and a setting button (operation unit) 6. A camera interface circuit 7, a camera connector 8, a console connector 9, an external input / output interface circuit 10, an external input / output connector 11, an external monitor interface circuit 12, and an external monitor connector 13. Including. The camera 102 includes an illumination unit 51 and an imaging unit 52. The imaging unit 52 includes an imaging device 21, a camera control circuit 22, a controller interface circuit 23, and a controller connector 24.

  An external monitor different from the LCD touch panel 4 can be connected to the external monitor connector 13. The same screen as the LCD touch panel 4 can be displayed on the external monitor. Instead of the setting button 6, a console for the user to give an instruction to the visual sensor 201 can be connected to the console connector 9. The camera 102 shown in FIG. 1 can be connected to the camera connector 8.

  The illumination unit 51 includes a plurality of illumination blocks and irradiates the measurement target with light. The imaging unit 52 images the measurement target irradiated with light by the illumination unit 51.

  The central control circuit 61 is realized by, for example, a CPU, a memory, an ASIC (Application Specific Integrated Circuit), and the like. Based on the operation information received from the LCD touch panel 4 and the setting button 6, the central control circuit 61 determines an illumination pattern that determines whether or not each illumination block is lit in the illumination unit 51 and the intensity of irradiation light of each illumination block. The central control circuit 61 performs control for outputting and setting an illumination pattern to the camera 102, control for displaying an image captured by the imaging unit 52 on the LCD touch panel 4, and the like.

  The camera control circuit 22 includes a PLD, a memory, and the like, performs illumination control of the illumination unit 51 based on the illumination pattern set by the controller 101, and controls the image sensor 21 to image the measurement object. The camera control circuit 22 outputs the captured image to the central control circuit 61 via the controller interface circuit 23, the controller connector 24, the camera connector 8, and the camera interface circuit 7.

  The LCD controller 3 displays an image on the LCD touch panel 4 based on the data received from the central control circuit 61.

  The touch panel controller 5 outputs operation information received from the LCD touch panel 4, that is, data indicating which position on the LCD touch panel 4 is operated by the user to the central control circuit 61.

  Setting button 6 outputs an operation signal representing the on state and the off state to central control circuit 61.

  The external input / output interface circuit 10 is, for example, a serial interface circuit such as a USB (Universal Serial Bus) interface circuit and an RS-232C / 422 interface circuit, or a parallel interface circuit or an Ethernet (registered trademark) interface circuit. It is. The external input / output interface circuit 10 performs input / output of signals between the central control circuit 61 and an externally connected personal computer and PLC (Programmable Logic Controller) via the external input / output connector 11.

  The camera interface circuit 7 and the controller interface circuit 23 are, for example, LVDS (Low Voltage Differential Signaling) circuits, and input / output of image data and control data between the central control circuit 61 and the imaging unit 52 and the camera connector 8 and This is done via the controller connector 24.

  FIG. 3 is a cross-sectional view showing the configuration of the camera 102 in the visual sensor according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating the configuration of the illumination unit 51 viewed from the direction IV in FIG.
With reference to FIG. 3 and FIG. 4, the illumination part 51 contains the half mirror 31, illumination block 32E-32I, and illumination block 33A-33D. The imaging unit 52 includes the imaging device 21, a controller connector 24, a manual zoom bar 25, and a lens 26.

  Each of the illumination blocks 32E to 32I includes a plurality of white LEDs and constitutes the coaxial illumination unit 32. Each of the illumination blocks 33 </ b> A to 33 </ b> D includes a plurality of white LEDs and constitutes a shadowless illumination unit 33.

  The coaxial illumination unit 32 irradiates the measurement target with light substantially parallel to the imaging optical axis of the imaging unit 52. The light irradiated from the illumination block 32I is reflected by the half mirror 31, and the reflected light is irradiated to the measurement object in substantially parallel to the imaging optical axis of the imaging unit 52. The shadowless illumination unit 33 irradiates the measurement target with light from a plurality of directions, thereby preventing the shadow of the measurement target from being formed. The illumination unit 51 may include a low-angle illumination unit instead of or in addition to the coaxial illumination unit 32 or the shadowless illumination unit 33.

  The shadowless illumination unit 33 is disposed outside the coaxial illumination unit 32 when viewed from the direction IV shown in FIG. 3, that is, the direction substantially parallel to the imaging optical axis of the imaging unit 52. The shadowless illumination unit 33 is provided at a position where the irradiation light of the shadowless illumination unit 33 and the imaging optical axis of the imaging unit 52 are not parallel to each other. A part or all of the light reflected from the measurement object is irradiated onto the image sensor 21 via the half mirror 31 and the lens 26.

  The imaging element 21 includes a plurality of light receiving elements. The light receiving element converts the received light into an electrical signal and outputs it to the camera control circuit 22.

The manual zoom bar 25 changes the magnification of the lens 26 based on a user operation.
FIG. 5 is a front view of the controller 101 in the visual sensor according to the embodiment of the present invention.

  Referring to FIG. 5, controller 101 includes an operation unit cover 14, LCD touch panel 4, setting button 6, camera connector 8, and external input / output connector 11.

  The setting button 6 includes an AUTO button 16A, an ESC button 16E, a SET button 16S, an upper button 16U, a lower button 16D, a left button 16L, and a right button 16R.

  The controller 101 is provided so that the user can operate the setting button 6 and the external input / output connector 11 to which a USB cable, an SD card and the like are connected in a state where the operation unit cover 14 is opened.

  Here, the display screen of the LCD touch panel 4 shown in FIG. 5 is referred to as a first setting screen. In the first setting screen, a schematic diagram of the illumination unit 51 is displayed on the upper left of the screen. In the lower part of the screen, the illumination intensity of each illumination block in the illumination unit 51 is displayed. On the upper right of the screen, an image of the measurement object captured by the camera 102 based on the illumination patterns displayed on the upper left and lower of the screen is displayed.

[Operation]
Next, the operation when the visual sensor according to the embodiment of the present invention determines the illumination pattern will be described.

  FIG. 6 is a front view of the controller in the visual sensor according to the embodiment of the present invention. Hereinafter, the display screen of the LCD touch panel 4 shown in FIG. 6 is referred to as a second setting screen.

  FIG. 7 is a flowchart defining an operation procedure when the visual sensor according to the embodiment of the present invention determines an illumination pattern.

  Referring to FIG. 7, first, when the user turns on the visual sensor 201 and operates the LCD touch panel 4 or the like to select the illumination adjustment menu, the first setting screen is displayed.

  The central control circuit 61 controls the illumination unit 51 and the imaging unit 52 to irradiate the measurement target with light based on the initial setting of the illumination pattern stored in advance, and images the measurement target. The central control circuit 61 acquires the image captured by the imaging unit 52, controls the LCD controller 3, and displays the acquired image on the LCD touch panel 4 (step S1).

  The central control circuit 61 waits until the user presses the setting button 6 (NO in step S2). On the other hand, the central control circuit 61 receives an operation signal indicating that the user has pressed the setting button 6 from the setting button 6 (YES in step S2), and when the operation signal indicates pressing of the upper button 16U. (NO in steps S3 and S4, YES in step S5), the illumination unit 51 is controlled to increase the illumination intensity by one level (step S11).

  Further, when the operation signal indicates pressing of the lower button 16D (NO in steps S3 to S5, YES in step S6), the central control circuit 61 controls the illumination unit 51 to decrease the illumination intensity by one level (step S12). ).

  After changing the illumination intensity, the central control circuit 61 controls the imaging unit 52 to newly image a measurement object (step S13). Then, the central control circuit 61 controls the LCD controller 3 to update the display content of the LCD touch panel 4, that is, to display a newly captured image on the LCD touch panel 4 (step S15).

  The central control circuit 61 controls the LCD controller 3 when the operation signal indicates that the left button 16L or the right button 16R is pressed (NO in steps S3 to S6, YES in step S7). The focus display is moved to a different illumination block from the illumination block on which the focus is displayed (steps S14 and S15).

  Further, when the operation signal indicates pressing of the “AUTO” button (NO in steps S3 to S7, YES in step S8), the central control circuit 61 executes a candidate selection HMI (Human Machine Interface) routine to be described later (step S16).

  Further, when the operation signal indicates pressing of the SET button 16S (YES in step S3), the central control circuit 61 determines the currently set illumination pattern of the illumination unit 51 and ends the process (step S9).

  Further, when the operation signal indicates pressing of the ESC button 16E (NO in step S3, YES in S4), the central control circuit 61 discards the currently set illumination pattern of the illumination unit 51 and ends the processing ( Step S10).

  FIG. 8 is a flowchart defining an operation procedure when the visual sensor according to the embodiment of the present invention executes the candidate selection HMI routine. Hereinafter, in order to simplify the description, it is assumed that N = 20 and M = 9.

  FIG. 9 is a diagram showing the contents of the lighting pattern of the visual sensor according to the embodiment of the present invention.

  Referring to FIG. 9, central control circuit 61 stores, for example, 20 types of lighting patterns. In FIG. 9, A to I correspond to the illumination blocks 33A to 33D and the illumination blocks 32E to 32I, respectively.

  Referring to FIG. 8, first, central control circuit 61 changes the display content of LCD touch panel 4 from the first setting screen to the second setting screen (step S21).

  The central control circuit 61 executes an illumination intensity determination routine for each of the lighting patterns 1 to 20 and irradiates each illumination block of the illumination unit 51 corresponding to the lighting patterns 1 to 20 based on the brightness of the image of the measurement object. Determine the intensity of each light. That is, the central control circuit 61 determines 20 types of illumination patterns that are combinations of each of the 20 types of lighting patterns and the intensity of irradiation light of each illumination block (steps S22 to S24).

  Then, the central control circuit 61 executes a candidate image selection routine. That is, the central control circuit 61 determines the 9th out of 20 primary candidate images based on the contrast of the 20 primary candidate images captured by the camera 102 based on the 20 types of illumination patterns. A secondary candidate image is selected (step S25).

  The central control circuit 61 displays the nine selected secondary candidate images on the LCD touch panel 4 (step S26).

  The central control circuit 61 waits until the user presses the setting button 6 (NO in step S27). The central control circuit 61 receives an operation signal indicating that the user has pressed the setting button 6 from the setting button 6 (YES in step S27), and when the operation signal indicates the pressing of the SET button 16S. (YES in step S28), it is recognized that the candidate image displayed in focus has been selected by the user (step S29). Then, the central control circuit 61 changes the display content of the LCD touch panel 4 from the second setting screen to the first setting screen (step S30). That is, the central control circuit 61 displays on the LCD touch panel 4 an image selected by the user and an illumination pattern corresponding to the image selected by the user.

  The central control circuit 61 receives an operation signal indicating that the user has pressed the setting button 6 from the setting button 6 (YES in step S27), and the operation signal is an upper button 16U, a lower button 16D, When the left button 16L or the right button 16R is pressed (NO in step S28, YES in step S31), a focus display is made from the currently focused candidate image to another candidate image according to the type of the pressed button. Move (steps S32 and S33).

  FIG. 10 is a flowchart defining an operation procedure when the visual sensor according to the embodiment of the present invention executes the illumination intensity determination routine. Here, the case where the central control circuit 61 determines the illumination intensity corresponding to the lighting pattern 1 will be representatively described.

  Referring to FIG. 10, central control circuit 61 sets lighting pattern 1 in illumination unit 51, and sets an initial value of illumination intensity, for example, the minimum illumination intensity, in illumination unit 51 (step S41).

  The central control circuit 61 controls the image pickup unit 52 to pick up an image of the measurement target, and acquires the picked up image (step S42).

  The central control circuit 61 executes an image evaluation determination routine for the acquired image (step S43). When the end condition is satisfied (YES in step S43), the central control circuit 61 determines the currently set illumination intensity as the illumination intensity corresponding to the lighting pattern 1 (step S45).

  On the other hand, if the end condition is not satisfied (NO in step S43), the central control circuit 61 increases the illumination intensity of the illumination unit 51 by one level (step S44), and captures the measurement object and determines the image evaluation. The routine is executed again (steps S42 and S43).

  FIG. 11 is a flowchart defining an operation procedure when the visual sensor according to the embodiment of the present invention executes an image evaluation determination routine.

  With reference to FIG. 11, the central control circuit 61 calculates the average value of the brightness of the pixels in the acquired image (step S51).

12A and 12B are diagrams illustrating an example of an acquired image.
Referring to FIG. 12A, the central control circuit 61 calculates, for example, the average value of the brightness of the entire acquired image, that is, all the pixels in the image.

  Further, the central control circuit 61 may be configured to calculate an average value of the brightness of a part of all the pixels in the area surrounded by the frame line A1 in FIG.

  Here, the pixels in the image correspond to the light receiving elements included in the image sensor 21, and the brightness of the pixels means the amount of light received by the light receiving elements. Most of the light received by the light receiving element is light reflected from the measurement object by the irradiation light from the illumination unit 51. Therefore, since the reflected light is not irradiated to the light receiving element from the part where the light reflection does not occur in the measurement object, the amount of light received by the light receiving element corresponding to such a part is as close to zero as possible.

FIG. 13 is a plan view illustrating an example of a measurement object.
Referring to FIG. 13, the measurement object is a metal plate with a hole. Thus, since the reflected light is not irradiated to the light receiving element from the holed portion, the amount of light received by the light receiving element corresponding to the holed portion is as close to zero as possible.

  Therefore, the central control circuit 61 may be configured to select a pixel whose brightness is a predetermined value or more from among a plurality of pixels in the acquired image and calculate an average value of the brightness of the selected pixel. . With such a configuration, image evaluation can be performed appropriately.

FIG. 14 is a graph showing the brightness distribution of each pixel in the image of the measurement object.
Referring to FIG. 14, a point where a distribution in which the brightness of the pixel is maximum exists is a saturation point, that is, an electric signal output from the light receiving element in the image pickup element 21 is saturated.

  Even if the average value of the brightness of the pixels is larger than the determination lower limit value, the central control circuit 61 sets the current setting because the reflected light is too strong when the ratio of pixels reaching the saturation point is large. The lighting intensity is judged to be inappropriate.

  That is, referring again to FIG. 11, the central control circuit 61 determines that the calculated average value is not less than the determination lower limit value (YES in step S52), not more than the determination upper limit value (YES in step S53), and reaches the saturation point. The ratio of the reached pixels is equal to or less than a predetermined value (YES in step S54), and the current illumination intensity setting is higher than the image captured last time, that is, the image captured with the illumination intensity one step lower than the current illumination intensity setting. If the average value of the brightness of each pixel in the image picked up in (5) is larger (YES in step S55), it is determined that the end condition is not satisfied (step S57).

  If the calculated average value is less than the determination lower limit value (NO in step S52), the central control circuit 61 determines that the end condition is not satisfied (step S57).

  On the other hand, the central control circuit 61 captures an image with the illumination intensity one step lower than the previous image, that is, the current illumination intensity setting, whether the percentage of pixels reaching the saturation point is greater than a predetermined value (NO in step S54). If the average value of the brightness of each pixel in the image captured with the current illumination intensity setting is smaller than the obtained image (NO in step S55), the illumination intensity is one step lower than the current illumination intensity setting. Is determined to be appropriate, and the illumination intensity of the illumination unit 51 is lowered by one level (step S56). Then, the central control circuit 61 determines that the end condition is satisfied (step S58).

  If the calculated average value is equal to or greater than the determination lower limit value (YES in step S52) and exceeds the determination upper limit value (NO in step S53), the central control circuit 61 sets 1 from the current illumination intensity setting. It is determined that the setting of the lower illumination intensity is appropriate, and the illumination intensity of the illumination unit 51 is lowered by one stage (step S56). Then, the central control circuit 61 determines that the end condition is satisfied (step S58).

  FIG. 15 is a flowchart defining an operation procedure when the visual sensor according to the embodiment of the present invention executes a candidate image selection routine. Here, the 20 primary candidate images corresponding to the 20 types of illumination patterns determined by the candidate image selection routine are referred to as primary candidate images 1 to 20.

Referring to FIG. 15, central control circuit 61 sets variable K = 1 (step S61).
The central control circuit 61 calculates the variation in brightness of each pixel in the first candidate image K (step S62). More specifically, the central control circuit 61 calculates the variance value of the brightness of each pixel in the primary candidate image K. For example, the central control circuit 61 calculates a variance value for the entire candidate image, that is, for all the pixels in the candidate image (hereinafter referred to as method A).

FIG. 16 is a diagram illustrating a method for calculating an average value of brightness of acquired images.
Referring to FIG. 16, in step S62, central control circuit 61 calculates an average value of brightness in a plurality of regions divided by frame A2, and calculates a variance value of the calculated plurality of average values. The structure to calculate may be sufficient (method B).

  Further, before performing the method A or the method B, the central control circuit 61 selects a pixel whose brightness is a predetermined value or more from among the plurality of pixels in the candidate image K, and the method A or the method is selected for the selected pixel. The structure which performs B may be sufficient.

  The central control circuit 61 sorts the primary candidate images 1 to K in descending order of brightness variation (step S63).

The central control circuit 61 adds 1 to the variable K (step S64).
When the variable K is less than the maximum number of candidates 20 (NO in step S65), the central control circuit 61 calculates brightness variation for the primary candidate image K (step S62).

  On the other hand, when the variable K is 20 or more, which is the maximum number of candidates (YES in step S65), the central control circuit 61 selects 9 from the first candidate images 1 to K in descending order of brightness variation. Images are selected as secondary candidate images (step S66). This is because the greater the variation in brightness, the higher the contrast and the better the image.

  By the way, in order to perform accurate measurement, it is necessary to set an appropriate illumination pattern according to the measurement object, and know-how and skill are required to set an appropriate illumination pattern. However, in the visual sensor according to the embodiment of the present invention, the illumination unit 51 irradiates the measurement object with light based on 20 types of illumination patterns. The imaging unit 52 acquires 20 primary candidate images by imaging each measurement target irradiated with light based on 20 types of illumination patterns. Based on the contrast calculated based on the brightness of the plurality of pixels in each of the 20 primary candidate images, the central control circuit 61 performs 9 second out of the 20 primary candidate images. Select the next candidate image. The LCD touch panel 4 displays nine secondary candidate images and recognizes an image selected by the user from the nine secondary candidate images. And the illumination part 51 irradiates light to a measuring object based on the illumination pattern corresponding to the image which the user selected. With such a configuration, it is possible to easily set an appropriate illumination pattern according to the measurement object without requiring know-how and learning.

  In the visual sensor according to the embodiment of the present invention, the central control circuit 61 determines the irradiation intensity corresponding to each of the 20 lighting patterns based on the brightness of the image of the measurement object, and the lighting pattern and Although it was set as the structure which determines 20 types of illumination patterns which are a combination with the intensity | strength of irradiation light, it is not limited to this. The central control circuit 61 may be configured to determine irradiation intensity corresponding to a plurality of types of lighting patterns based on the contrast calculated from the brightness of the image of the measurement object. Further, the central control circuit 61 may store a plurality of predetermined illumination patterns.

  In the visual sensor according to the embodiment of the present invention, the central control circuit 61 uses the 20 first candidate images based on the contrast of the 20 primary candidate images captured based on the 20 types of illumination patterns. Although nine secondary candidate images are selected from the next candidate images, the present invention is not limited to this. The central control circuit 61 may be configured to select the secondary candidate image based on other evaluation values calculated based on the brightness of the plurality of pixels in the primary candidate image, not limited to the contrast. it can.

  For example, the central control circuit 61 performs general edge extraction on the primary candidate image and calculates the magnitude of the brightness change of the extracted edge portion. More specifically, the central control circuit 61 calculates an average value of the brightness of all the pixels corresponding to the extracted edge portion. Alternatively, the central control circuit 61 is configured to select a pixel whose brightness is equal to or higher than a predetermined value from among a plurality of pixels corresponding to the extracted edge portion, and calculate an average value of the brightness of the selected pixel. May be. This is because the greater the change in the brightness of the extracted edge portion, the higher the contrast and the better the image.

  Further, the central control circuit 61 determines, for example, that the average value of the brightness of each pixel is within a predetermined range based on the brightness of the 20 primary candidate images captured by the camera 102 based on the 20 types of illumination patterns. Based on whether or not there is, it is possible to adopt a configuration in which nine secondary candidate images are selected from the 20 primary candidate images. In such a configuration, the possibility that 10 or more secondary candidate images are selected instead of 9 is higher than that in the case of using contrast. In such a case, 10 or more secondary screen images are used on two screens. The secondary candidate image may be displayed and dealt with, or the secondary candidate image may be reduced and displayed on one screen.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a perspective view which shows the structure of the visual sensor which concerns on embodiment of this invention. It is a functional block diagram which shows the structure of the visual sensor which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the camera 102 in the visual sensor which concerns on embodiment of this invention. It is a figure which shows the structure of the illumination part 51 seen from the direction of IV in FIG. It is a front view of the controller 101 in the visual sensor which concerns on embodiment of this invention. It is a front view of the controller in the visual sensor which concerns on embodiment of this invention. It is the flowchart which defined the operation | movement procedure at the time of the visual sensor which concerns on embodiment of this invention determines an illumination pattern. It is the flowchart which defined the operation | movement procedure at the time of the visual sensor which concerns on embodiment of this invention performs candidate selection HMI routine. It is a figure which shows the content of the lighting pattern which the visual sensor which concerns on embodiment of this invention has. It is the flowchart which defined the operation | movement procedure at the time of the visual sensor which concerns on embodiment of this invention performs illumination intensity determination routine. It is the flowchart which defined the operation | movement procedure at the time of the visual sensor which concerns on embodiment of this invention performs image evaluation determination routine. (A) And (b) is a figure which shows an example of the acquired image. It is a top view which shows an example of a measurement target object. It is a graph which shows distribution of the brightness of each pixel in the image of a measurement object. It is the flowchart which defined the operation | movement procedure at the time of the visual sensor which concerns on embodiment of this invention performs candidate image selection routine. It is a figure which shows the method of calculating the average value of the brightness of the acquired image.

Explanation of symbols

  3 LCD controller, 4 LCD touch panel (display unit and operation unit), 5 touch panel controller, 6 setting button (operation unit), 7 camera interface circuit, 8 camera connector, 9 console connector, 10 external input / output interface circuit, 11 External I / O connector, 12 External monitor interface circuit, 13 External monitor connector, 14 Operation unit cover, 16A AUTO button, 16E ESC button, 16U Up button, 16D Down button, 16L Left button, 16R Right button, 16S SET button , 21 Image sensor, 22 Camera control circuit, 23 Controller interface circuit, 24 Controller connector, 25 Manual zoom bar, 26 Lens, 31 Half mirror, 32 Coaxial illumination unit, 33 Shadow lighting unit, 32E～32I, 33A to 33D lighting block, 51 illumination unit, 52 image pickup unit, 61 central control circuit (control unit), 101 controller, 102 camera, 201 visual sensor.

Claims (6)

A plurality of illumination blocks are included, and light is applied to the measurement object based on m (m is a natural number of 3 or more) types of illumination patterns that determine whether or not each illumination block is turned on and the intensity of irradiation light of each illumination block. An illumination unit to irradiate;
An imaging unit that acquires m primary candidate images by imaging each of the measurement objects irradiated with light based on the m types of illumination patterns;
M calculated based on the brightness of a plurality of pixels in each of the acquired m primary candidate images and the brightness of a plurality of pixels in each of the acquired m primary candidate images. A control unit that selects n (n is a natural number satisfying 2 ≦ n <m) secondary candidate images from the m primary candidate images based on at least one of the evaluation values. When,
A display unit for displaying the selected n secondary candidate images;
And an operation unit operated by the user to select a user Gae image from among the displayed n second-order candidate image,
The illumination unit is a visual sensor that irradiates light to the measurement object based on the illumination pattern used when an image selected by the user is taken . The control unit stores m kinds of lighting patterns that determine whether or not each lighting block is turned on,
The illumination unit irradiates a measurement target with light based on the m kinds of lighting patterns,
The imaging unit acquires m images by imaging each of the measurement objects irradiated with light based on the m kinds of lighting patterns,
Wherein, based on the brightness of a plurality of pixels in each of the acquired m pieces of image, by associating the intensity of the irradiation light of each illumination blocks in each of the m types of lighting patterns, the The visual sensor according to claim 1 , wherein m types of illumination patterns are determined.   The control unit calculates a contrast of each of the m primary candidate images as the evaluation value based on brightness of a plurality of pixels in each of the acquired m primary candidate images. Item 18. A visual sensor according to item 1.   The control unit calculates a variance value of brightness of a plurality of pixels in each of the acquired m primary candidate images as the evaluation value of each of the m primary candidate images. 3. The visual sensor according to 3. The plurality of illumination blocks irradiate light to the measurement object from different directions,
2. The visual sensor according to claim 1, wherein the control unit determines the m types of illumination patterns so that light is emitted from different directions in the m types of illumination patterns. A first light that irradiates the measurement object with light based on m (m is a natural number of 3 or more) types of illumination patterns that determine whether or not the plurality of illumination blocks are turned on and the intensity of irradiation light of the plurality of illumination blocks. A lighting step;
An imaging step of acquiring m primary candidate images by imaging each of the measurement objects irradiated with light based on the m types of illumination patterns;
M calculated based on the brightness of a plurality of pixels in each of the acquired m primary candidate images and the brightness of a plurality of pixels in each of the acquired m primary candidate images. Image selection for selecting n (n is a natural number satisfying 2 ≦ n <m) secondary candidate images from the m primary candidate images based on at least one of the evaluation values Steps,
A display step of displaying the selected n secondary candidate images;
A recognition step for recognizing an image selected by the user from the displayed n second candidate images;
And a second illumination step of irradiating the measurement object with light based on the illumination pattern used when the image selected by the user is taken .