JP2020122662A - Illumination device for surface inspection and surface inspection device - Google Patents

Abstract

To provide an illumination device for surface inspection which can optionally change a direction and width of pattern illumination to an object to be inspected while rapidly drawing an illumination pattern 13.SOLUTION: The illumination device for surface inspection comprises: a liquid crystal drawing portion 10 which draws the illumination pattern 13 having a bright belt-like portion 13a and a dark belt-like portion 13b which are alternately arranged by a raster scanning system; and an FPGA 12 (a control device) which is for drawing the illumination pattern 13 on the liquid crystal drawing portion 10. The FPGA 12, which forms a processing circuit which sequentially calculates drawing data of each of scan lines for drawing the illumination pattern 13 on the liquid crystal drawing portion 10 according to a predetermined drawing parameter, draws the illumination pattern 13 on the liquid crystal drawing portion 10 by using the sequentially calculated drawing data of each of the scan lines.SELECTED DRAWING: Figure 4

Description

The present invention relates to a surface inspection illumination device for irradiating a surface of an inspection object with pattern illumination in which bright strips and dark strips are alternately arranged, and a surface inspection device incorporating the same.

As a method for inspecting products with smooth surfaces (glass products, film products, products with plating or coating on the surface, etc.) to see if there are defects such as unevenness or scratches on the surface A surface inspection device using pattern illumination in which bright strips and dark strips are alternately arranged is widely known (for example, see Patent Document 1).
A liquid crystal illumination device capable of drawing an illumination pattern on a liquid crystal drawing unit is incorporated in the surface inspection device as a light source for irradiating pattern illumination.

This type of surface inspection apparatus uses a plurality of images obtained by irradiating the surface of the inspection object while shifting the brightness of the pattern of the pattern illumination and capturing the surface of the inspection object to obtain a difference in reflected light amount. The presence or absence of a defect on the surface is inspected on the basis of the change of the brightness or the brightness (for the principle of the inspection method, see, for example, Non-Patent Documents 1 and 2).

When the inspection target has a complicated shape and a wide variety (for example, an inspection line where multiple body types flow in a car body), there are normal surface parts and parts with defects such as irregularities and scratches. It is necessary to change the widths of the bright and dark strips in the pattern illumination and the orientations of the strips with respect to the surface of the inspection target so that the difference in the amount of reflected light and the brightness becomes large.

Therefore, in the conventional surface inspection apparatus, a light source (illumination device) for irradiating pattern illumination is attached to the robot arm, and the direction of the pattern illumination is driven by the robot arm (specifically, the direction of each strip of light and dark). ) There are some that adopt a configuration that changes.
Further, a frame memory is mounted in the control unit of the liquid crystal lighting device, element data of various variations of the illumination pattern is stored in the memory, and the element data of the optimal illumination pattern is read and used according to the inspection target. A conventional device adopting the configuration is also known.

However, in the conventional device configured to change the direction of the pattern illumination by driving the robot arm, there is a drawback that the control of the robot arm is complicated, the entire device becomes large, and the equipment cost becomes high. It was
Further, in the conventional lighting device configured to store the element data of various variations of the illumination pattern in the frame memory, a large-capacity frame memory is required, and the control unit becomes large, and Not only is the cost high, but it also takes time to read the element data from the frame memory, so it is not possible to draw the illumination pattern quickly, which hinders the speedup of surface inspection. ..

Utility model registration No. 3197766

Osamu Hirose, 3 others, "Detection of irregularities on film surface using pattern illumination", Journal of Precision Engineering, VOL.66, No.7, 2000, P1098-1102 Shin Uzawa, 1 person, "Development of defect detection technology using moving pattern light source", Japan Society for Precision Engineering, VOL.67, No.11, 2001, P1839-1843

The present invention has been made in view of the above-described circumstances, does not require auxiliary equipment such as a robot arm, can arbitrarily change the direction of pattern illumination with respect to an inspection target, and quickly draws an illumination pattern. An object of the present invention is to provide a lighting device for surface inspection which can be used.

In order to achieve the above-mentioned object, the present invention irradiates the surface of an inspection target with pattern illumination in which bright strips and dark strips having different lightnesses are alternately arranged, and obtains by imaging the surface of the inspection target. A surface inspection illuminating device for irradiating the surface of the inspection target with pattern illumination, which is incorporated in a surface inspection device for inspecting the surface state of the inspection target using the obtained image, and has the following configuration. It is characterized by that.
That is, the illumination device for surface inspection according to the present invention, for drawing the illumination pattern in the raster scanning method, the drawing unit for drawing the illumination pattern in which the bright strips and the dark strips are arranged alternately, The control device constitutes a processing circuit that sequentially calculates drawing data for each scanning line for drawing an illumination pattern on the drawing unit according to a drawing parameter set in advance. It is characterized in that an illumination pattern is drawn on the drawing unit by the drawing data for each scanning line that is sequentially calculated.

As described above, the lighting apparatus for surface inspection according to the present invention is configured to draw the illumination pattern on the drawing unit based on the drawing data for each scanning line that is sequentially calculated by the control device. It is not necessary to store the element data of the illumination pattern, and the illumination pattern can be drawn quickly.

Here, the control device draws, as drawing parameters, the width dimension in the scanning direction of the bright strips forming the illumination pattern, the width dimension in the scanning direction of the dark strips, and the slanted rendering of each strip. And the shift amount of each strip in the scanning direction for each scanning line are set in advance, and each scanning line for drawing the illumination pattern on the drawing unit based on the drawing parameters including these set values. The drawing data for each can be sequentially generated.

Further, the control device described above is preset with a value obtained by converting the shift amount for moving each strip in the width direction into the scanning direction as a drawing parameter, and based on the drawing parameter including this set value, the drawing unit It is also possible to adopt a configuration in which drawing data for each scanning line for drawing an illumination pattern is sequentially generated.

The control device described above can be configured by, for example, an FPGA (Field Programmable Gate Array).

A surface inspection apparatus according to the present invention is characterized by incorporating the above-described surface inspection illumination device as a light source.

As described above, the lighting device for surface inspection according to the present invention is configured to draw the illumination pattern on the drawing unit by the drawing data for each scanning line that is sequentially calculated by the control device, and therefore, the surface inspection lighting device can be used for various purposes in the frame memory. It is not necessary to store the element data of various variations of the illumination pattern, and the illumination pattern can be drawn quickly.

(A) is a schematic diagram which shows the outline of the surface inspection apparatus which concerns on embodiment of this invention, (b)-(e) is the illumination drawn by the liquid crystal drawing part in the illuminating device for surface inspection which concerns on embodiment of this invention. It is a figure which shows the specific example of a pattern. It is a figure for demonstrating the structure of a general liquid crystal drawing part, and the signal for drawing an illumination pattern on a liquid crystal drawing part. (A)-(d) is a figure for demonstrating the setting element required in order to produce|generate an illumination pattern in the illuminating device for surface inspections which concern on embodiment of this invention. It is a block diagram which shows the outline|summary of the processing circuit comprised in the FPGA with which the illuminating device for surface inspections which concerns on embodiment of this invention is comprised, and for drawing an illumination pattern. It is a figure for explaining drawing data output to a scanning line of a liquid crystal drawing part by a lighting installation for surface inspection concerning an embodiment of the present invention. It is a figure for demonstrating the other drawing data output to the scanning line of the liquid crystal drawing part by the illuminating device for surface inspection which concerns on embodiment of this invention. It is a figure for demonstrating further another drawing data output to the scanning line of the liquid crystal drawing part by the surface inspection illuminating device which concerns on embodiment of this invention. It is a figure for demonstrating further another drawing data output to the scanning line of the liquid crystal drawing part by the surface inspection illuminating device which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The surface inspection apparatus according to the present embodiment uses various products having a smooth surface, such as glass products, film products, and products whose surfaces are plated or coated, to be inspected 4, and the surface has irregularities or scratches. It has a function of inspecting whether or not there is a defect.

FIG. 1A is a schematic diagram showing an outline of a surface inspection apparatus according to an embodiment of the present invention.
The surface inspection device is configured to include a surface inspection illumination device (hereinafter, also simply referred to as an illumination device) 1, an imaging device 2, and a computer 3.
The illumination device 1 is a component serving as a light source for irradiating the surface of the inspection object 4 with pattern illumination for surface inspection. In the present embodiment, a liquid crystal illumination device including a liquid crystal drawing unit 10 is adopted. The liquid crystal lighting device can draw various illumination patterns on the liquid crystal drawing unit 10 according to the drawing data, and irradiate the inspection object 4 with light rays from the backlight 11 through the liquid crystal drawing unit 10.

The image pickup device 2 is a component for picking up an image of the surface of the inspection object 4 and obtaining an image of the surface. For example, a digital video camera or the like can be adopted as the image pickup device 2.
The computer 3 has a function as a central control unit for controlling the illumination device 1 and the imaging device 2 in synchronization with each other, and uses the surface image of the inspection target 4 acquired by the imaging device 2 to determine the presence or absence of a defect. It also has an inspection function. Since the principle of the surface inspection processed by the computer 3 is already well known, detailed description is omitted (for example, refer to Patent Document 1, Non-Patent Documents 1 and 2).

The lighting device 1 has a control device for drawing an illumination pattern in the liquid crystal drawing unit 10. Specifically, an FPGA (Field Programmable Gate Array) 12 is adopted as a control device.
The FPGA 12 is a semiconductor integrated circuit capable of constructing an arithmetic program by hardware, and is characterized in that the arithmetic program circuit can be freely set by the user and can be freely changed thereafter. Further, the FPGA 12 has a feature that it can realize extremely high-speed arithmetic processing as compared with a microcomputer that reads out the arithmetic program by software and executes the arithmetic processing because the arithmetic processing is executed by the arithmetic program constructed by hardware. Have
The illumination device 1 according to the present embodiment realizes the high-speed drawing process of the illumination pattern by executing the drawing process of the illumination pattern on the liquid crystal drawing unit 10 by the FPGA 12.

1B to 1E are diagrams showing specific examples of the illumination pattern drawn on the liquid crystal drawing unit in the lighting device according to the present embodiment.
In the present embodiment, the illumination pattern 13 used for the surface inspection employs a striped illumination pattern in which bright strip portions 13a and dark strip portions 13b having different lightness are alternately arranged. The strips 13a and 13b may be drawn in any color as long as the brightness is different, but in the present embodiment, the bright strips are white strips 13a and the dark strips are black strips 13b. ..

For example, the illumination pattern 13 of FIGS. 1B and 1C has a configuration in which the strip portions 13a and 13b are inclined with respect to the horizontal axis (scanning direction) of the liquid crystal drawing unit 10. The illumination pattern 13 of d) has vertical stripes formed by vertically arranging the strip portions 13a and 13b with respect to the horizontal axis of the liquid crystal drawing unit 10. The illumination pattern 13 of FIG. The strip portions 13a and 13b are arranged in parallel to the horizontal axis of the drawing unit 10 to form a horizontal stripe pattern.
The illumination device 1 according to the present embodiment is configured to draw such various illumination patterns 13 on the liquid crystal drawing unit 10 at high speed by the arithmetic processing by the FPGA 12.

FIG. 2 is a diagram for explaining a configuration of a general liquid crystal drawing unit and a signal for drawing an illumination pattern on the liquid crystal drawing unit.
The liquid crystal drawing unit 10 is composed of a drawing area 14 and a non-drawing area 15 around the drawing area 14, and synchronously controls the entire area by a vertical synchronizing signal (VS) and a horizontal synchronizing signal (HS). Further, a video signal (R, G, B) is output in synchronization with the drawing area 14 by a DE signal (DE: Data Enable), and thereby a desired illumination pattern 13 is drawn in the drawing area 14. There is.
It should be noted that the control method of the liquid crystal drawing unit 10 based on the above-mentioned signals is an example, and various other control methods are already known, and the illumination device 1 of the present invention can appropriately select and employ them. Of course.

The illumination device 1 according to the present embodiment draws the illumination pattern 13 on the liquid crystal drawing unit 10 by the raster scan method.
In the liquid crystal drawing unit 10, a large number of pixels are arranged in a horizontal line to form a scan line, and a large number of scan lines from the first line to the final line are vertically arranged from top to bottom. They are arranged in a direction to form a two-dimensional frame (screen).
In the raster scanning method, drawing data is normally output from the left to the right in FIG. 2 with respect to the scanning lines arranged in parallel with the horizontal axis of the liquid crystal drawing unit 10, and the drawing data is sequentially moved to the lower scanning lines. While repeating, the two-dimensional illumination pattern 13 is drawn on the liquid crystal drawing unit 10.

In this way, after the illumination pattern 13 is drawn in the first frame (first frame), the process moves to the drawing of the next frame (second frame), the same illumination pattern 13 is continuously drawn, and this drawing process is performed in the frame. Change and repeat. As a result, unless the conditions are changed, the liquid crystal drawing unit 10 continues to draw a predetermined illumination pattern in a fixed state.

FIG. 3 is a diagram for explaining setting elements necessary for generating an illumination pattern.
As shown in (a) and (b) of the figure, in the illumination device 1 according to the present embodiment, the inclination angle θ of each of the strip portions 13a and 13b with respect to the horizontal axis parallel to the direction of the scanning line is arbitrarily set. By forming the illumination pattern 13, the orientation of each strip 13a, 13b can be freely changed in various directions. Thereby, the direction of the illumination pattern 13 with respect to the surface of the inspection target can be changed without using an external mechanism such as a robot arm.
Further, the width dimension Wa of the white strip portion 13a and the width dimension Wb of the black strip portion 13b can be set arbitrarily.

As described above, in the illumination device 1 according to the present embodiment, the illumination pattern 13 is drawn on the liquid crystal drawing unit 10 by the raster scanning method, so that each strip 13a, 13b is in the scanning direction (that is, parallel to the horizontal axis). Direction), it is necessary to convert the width dimension Wa of the white strip portion 13a and the width dimension Wb of the black strip portion 13b into dimension values in the scanning direction.
As shown in FIG. 3D, the width dimension Ha of the white strip portion 13a in the scanning direction can be calculated by the equation Ha=Wa/sin θ. Similarly, the width dimension Hb of the black strip portion 13b in the scanning direction can be calculated by the equation Hb=Wb/sin θ.

Further, in accordance with the set value of the inclination angle θ of each strip 13a, 13b, each strip 13a, 13b is shifted in the scanning direction for each scanning line for drawing with inclination. It is necessary to calculate the amount (shift amount between lines) c. This line-to-line shift amount c can be calculated by the equation c=1/tan θ.
By adding the shift amount between the lines in the drawing process of each scanning line, the two-dimensional illumination pattern 13 in which the strip portions 13a and 13b are inclined can be drawn in the liquid crystal drawing unit 10.

Further, in the present embodiment, with respect to the illumination pattern 13 drawn on the liquid crystal drawing unit 10, a shift amount L for sequentially moving the strip-shaped portions 13a and 13b in the width direction can be set in advance. This is for shifting the illumination pattern 13 and acquiring an image when performing an inspection. For example, when the surface inspection is performed based on the principle described in Non-Patent Document 2, it is necessary to shift the illumination pattern 13 between frames to draw.

When this shift amount L is set, it is necessary to convert the shift amount L into a shift amount (interframe shift amount) s in the scanning direction. As shown in FIG. 3D, the interframe shift amount s can be calculated by the equation s=L/sin θ.
The inter-frame shift amount s is set to a value smaller than the smaller one of the width dimension Ha of the white strip portion 13a in the scanning direction and the width dimension Hb of the black strip portion 13b in the scanning direction. ..

In the present embodiment, as shown in FIG. 3(c), the inclination angle θ of each of the strip portions 13a and 13b with respect to the scanning direction is set to an angle of 0° parallel to the horizontal axis, and this is the origin in the clockwise direction. The tilt is defined as positive (+) and the counterclockwise tilt is defined as negative (-). Further, the movement in the scanning direction (from left to right in FIG. 3D) is defined as positive (+), and the opposite direction (also from right to left) is defined as negative (-).

FIG. 4 is a block diagram showing an outline of a processing circuit for drawing an illumination pattern configured inside the FPGA.
The processing circuit for drawing the illumination pattern 13 includes a video timing generation unit 20 and an illumination pattern generation unit 21.

The video timing generation unit 20 includes a horizontal total pixel number, a horizontal active pixel number, a vertical total line number, a vertical active line number, and a horizontal pixel offset based on the specifications of the liquid crystal drawing unit 10 to be drawn. Each information of the amount and the vertical line offset amount is set in advance. The horizontal total number of pixels is the number of pixels forming a scanning line extending in the horizontal direction in the liquid crystal drawing unit 10 shown in FIG. The number of horizontal active pixels is the number of pixels arranged in the drawing area 14 in the figure among the pixels forming the scanning line. The vertical total number of lines is the total number of scanning lines arranged in the vertical direction in the liquid crystal drawing unit 10 of FIG. The number of vertical active lines is the number of scanning lines arranged in the drawing area 14 in the figure among the total number of scanning lines.

When the liquid crystal drawing unit 10 to be drawn is changed, these set values are rewritten based on the changed specifications of the liquid crystal drawing unit 10. By configuring the video timing generation unit 20 separately from the illumination pattern generation unit 21, which will be described later, when the specification of the liquid crystal drawing unit 10 is changed (for example, the resolution is changed), the set value of only the video timing generation unit 20 is set. Since changes can be dealt with, it is easy to deal with the changes in specifications.

The video timing generation unit 20 uses the vertical synchronization signal (VS), the horizontal synchronization signal (HS) and the DE signal shown in FIG. 2 and the timing signal for calculating the drawing initial value as clock signals based on these setting information. Output at the correct timing. Of these output signals, the vertical synchronizing signal (VS) and the horizontal synchronizing signal (HS) are sent to the liquid crystal drawing unit 10. Further, the DE signal is sent to the illumination pattern generation unit 21 and the liquid crystal drawing unit 10, respectively. Then, the calculation timing signal of the drawing initial value is sent to the illumination pattern generation unit 21.

The illumination pattern generation unit 21 is preset with a setting value regarding the illumination pattern 13 drawn on the liquid crystal drawing unit 10 as a drawing parameter.
In the present embodiment, each of the width dimension Ha in the scanning direction of the white strip portion 13a, the width dimension Hb in the scanning direction of the black strip portion 13b, the inter-line shift amount c, and the inter-frame shift amount s shown in FIG. The set value is preset in the illumination pattern generation unit 21 as a drawing parameter. These set values can be rewritten arbitrarily.

When the frame initial value is input from the video timing generation unit 20, the illumination pattern generation unit 21 draws the first scanning line (first line) of each frame drawn in the liquid crystal drawing unit 10 based on these drawing parameters. The drawing data is generated and output to the liquid crystal drawing unit 10. Further subsequently, the drawing data (video signal) for each scanning line is sequentially generated in synchronization with the DE signal input from the video timing generation unit 20.

The drawing parameters described above are set in the illumination pattern generation unit 21 in a fixed-point format with no sign.
For example, when the liquid crystal drawing unit 10 to be drawn is composed of a full HD liquid crystal display having a screen resolution of 1920×1080 pixels, the liquid crystal drawing unit 10 has at least one strip-shaped portion 13a or 13b, respectively. Assuming that drawing is performed, it is sufficient to set the maximum value of the width dimensions Wa and Wb of the strip portions 13a and 13b to a dimension width half the 1920 pixels (960 pixels). Then, when the inclination angle θ is set to 1°, the width dimensions Ha and Hb in the scanning direction of the strip portions 13a and 13b become maximum values.
The widths Ha and Hb in the scanning direction of the strip portions 13a and 13b at that time are Ha=Hb=960/sin1°=5506.741. At least 16 bits are required to arithmetically process the five digits of the integer part of the numerical value with a binary number, and similarly, at least 12 bits are required to arithmetically process the three digits of the decimal point part of the numerical value with a binary number.

Therefore, in this embodiment, a fixed point format is used in which 16 bits are assigned to the integer part and 12 bits are assigned to the decimal point part.
Here, the illumination pattern generation unit 21 executes the calculation process including the decimal point part, but the result obtained by the calculation process is configured to create the drawing data of the illumination pattern 13 using only the integer part. .. As a result, the configuration of the processing circuit built in the FPGA 12 can be simplified and the illumination pattern 13 can be drawn at a higher speed. In the above description, the inclination angle θ of each strip 13a, 13b is set to 1° when obtaining the maximum value concerning the widths Ha, Hb in the scanning direction of each strip 13a, 13b. Because it was examined in.
The specification of the illumination pattern generation unit 21 built in the FPGA 12 is not limited to this.

As described above, when the illumination pattern generation unit 21 creates the drawing data of the illumination pattern 13 using only the integer part of the fixed point format, the inclination angle θ of each strip 13a, 13b is 0°, that is, FIG. When drawing the horizontal striped illumination pattern 13 as shown in e), inconvenience may occur in the arithmetic processing.
That is, since the line shift amount c is c=1/tan0°=∞, it is an integer part processed by a 16-bit binary number, and a horizontal striped illumination pattern with an accurate inclination angle θ=0° is used. 13 cannot be drawn.

Therefore, in the present embodiment, the capacity of the integer part of the fixed-point format is increased (for example, changed from 16 bits to 28 bits) only when the horizontal stripe illumination pattern 13 having the inclination angle θ=0° is drawn. I am trying to respond. This makes it possible to approximate the horizontal striped pattern with the inclination angle θ=0° and draw the illumination pattern 13 that visually looks like the horizontal striped pattern. However, in this case, a circuit corresponding to θ=0° needs to be built in the FPGA 12.
Alternatively, a mode may be prepared in which the integer part corresponds to 28 bits from the beginning for all angles including θ=0°. In this case, the same circuit in the FPGA 12 can draw all angles.

Further, only when the horizontal stripe illumination pattern 13 with the inclination angle θ=0° is drawn, the algorithm is changed to read the drawing data of the horizontal stripe illumination pattern 13 with the inclination angle θ=0° prepared from the memory. It may be configured to output to the liquid crystal drawing unit 10 in accordance with the above.

Next, a method of drawing the illumination pattern 13 on the liquid crystal drawing unit 10 by the above-described lighting pattern generation unit 21 will be described.
5 and 6 are diagrams for explaining drawing data output to the scanning lines of the liquid crystal drawing unit 10.
In order to draw the illumination pattern 13 (for example, the illumination pattern of FIG. 1B or 1C) in which the strip portions 13a and 13b are inclined with respect to the scanning direction, a predetermined offset amount is added for each scanning line. Then, the drawing process is executed. In the following drawing method based on FIG. 5 and FIG. 6, the shift amount L (interframe shift amount s) is not set, and the lighting pattern 13 continues to be drawn on the liquid crystal drawing unit 10 in a stationary state.

In the present embodiment, when drawing the illumination pattern 13 in which the inclination angle θ of each of the strips 13a and 13b with respect to the scanning line has a positive (+) value, the drawing process is executed according to the procedure shown in FIG.

First, in the first scanning line (first line) in the first frame (initial frame) of the liquid crystal drawing unit 10, the first strip-shaped portion is set as the offset portion A, and the offset portion A is drawn as follows. .. That is, the entire width of the one strip 13a or 13b is set to the offset amount e _1, and the color of the one strip 13a or 13b is set to the offset color (black or white in the present embodiment, and adjacent strips 13a or 13b). Set so that the color of the copy does not become the same), and the offset part A is drawn. After that, the other strip-shaped portion 13b or 13a and the one strip-shaped portion 13a or 13b are continuously and alternately drawn.

In the specific example shown in FIG. 5, with respect to the offset portion A in the first line, the entire width Ha of the white strip portion 13a is set to the offset amount e ₁ and drawn. Further, the black strip portion 13b and the white strip portion 13a are alternately drawn in succession to the offset portion A.

Next, for the scanning line of the nth line (nth line, n is a natural number) in the initial frame, as a general rule, the inter-line shift amount c is sequentially subtracted from the offset portion A (first strip portion). That is, in the second line, the offset amount A is drawn by subtracting the inter-line shift amount c from the offset amount e ₁ set in the first line. In the subsequent third line, the offset amount A is drawn by subtracting the inter-line shift amount c from the offset amount e ₂ set in the second line.
Next to the offset portion A of each line, drawing is performed so that the strip portions 13a and 13b of different colors are alternately arranged.

Here, the width of the strip-shaped portion (second strip-shaped portion) drawn next to the offset portion A is a, and the width of the strip-shaped portion (third strip-shaped portion) drawn next is b.

When the offset amount en _-1 of the ( _n-1 )th line becomes smaller than the inter-line shift amount c (en _-1 <c), the second strip-shaped portion on the ( _n-1 )th line is used. use width a, calculates and sets the offset amount e _n of the next n-th line. The offset amount _{e n} is, _{a- |} a | _{e n-1} -c.

Specifically, as shown in the third line of FIG. 5, when the offset amount e ₃ becomes smaller than the inter-line shift amount c (e ₃ <c), the second strip shape in the third line is formed. Using the width a of the part, the offset amount e ₄ of the next fourth line is calculated and set. Offset _{e 4} of the fourth line, a- _| e 3 -c _| become. After the drawing is completed up to the last line, the drawing is started from the first line, and the offset amount is returned to the initial set value e ₁ at that time. By doing so, unless a particular initial condition is changed, a predetermined illumination pattern is fixed and continues to be drawn on the liquid crystal drawing unit 10.

Next, when drawing the illumination pattern 13 in which the inclination angle θ of each of the strip portions 13a and 13b with respect to the scanning line is a negative (−) value, the drawing process is executed in the procedure shown in FIG.

First, the offset amount is set to zero for the first scanning line (first line) in the first frame (initial frame) of the liquid crystal drawing unit 10, and drawing is started from one of the strip portions 13a or 13b, and then continued. , The strips 13a and 13b are drawn alternately so that the adjacent strips do not have the same color.

In the specific example shown in FIG. 6, the first line is drawn from the white band-shaped portion 13a, and the black band-shaped portion 13b and the white band-shaped portion 13a are alternately drawn continuously.

Next, for the scanning line of the nth line (nth line, n is a natural number) in the initial frame, as a general rule, the first strip portion is set to the offset portion A, and the offset amount A is set to the line shift amount c. Sequentially add.

In the specific example shown in FIG. 6, the offset portion A of the second line is drawn in a black color different from that of the first strip portion (white strip portion 13a) of the first line. Since the offset amount of the first line was zero, the offset amount e ₂ of the second line is the inter-line shift amount c. In the subsequent third line, the offset amount e ₂ set in the second line is added with the inter-line shift amount c in the same color to draw the offset portion A.
Next to the offset portion of each line, drawing is performed so that strip portions 13a and 13b of different colors are alternately arranged.

Also in this case, the width of the strip portion (second strip portion) drawn next to the offset portion A is a, and the width of the strip portion (third strip portion) drawn next is a.

Then, if the value obtained by adding the offset amount e _n-1 to the line between the shift amount c of the n-1 line, becomes larger than the width b of the third strip portion in the n-1 line (e _{n -1 + c} to> b), using the width b of the third strip portion in the n-1 line, calculates and sets the offset amount e _n of the next n-th line. The offset amount _{e n becomes e n-1 + c-b} . Then, the color of the offset portion A is changed to another color.

Specifically, as shown in the third line in FIG. 6, when the value obtained by adding the inter-line shift amount c to the offset amount e ₃ is larger than the width b of the third strip in the third line. The width b of the third strip in the third line is used for (e ₃ +c>b) to calculate and set the offset amount e ₄ of the next fourth line. That is, the offset amount e ₄ of the next fourth line is e ₃ +c−b. The color of the offset portion A of the fourth line is changed to white. After the drawing is completed up to the last line, the drawing is started from the first line, and the offset amount is returned to the initial setting value (zero). By doing so, unless a particular initial condition is changed, a predetermined illumination pattern is fixed and continues to be drawn on the liquid crystal drawing unit 10.

Next, a method of drawing the illumination pattern 13 when the shift amount L is set will be described with reference to FIGS. 7 and 8.
When the shift amount L is preset for the illumination pattern 13 drawn on the liquid crystal drawing unit 10, the illumination pattern 13 moved in the scanning direction or the opposite direction by the inter-frame shift amount s shown in FIG. 3D. Is drawn for each frame.

For example, as shown in FIG. 7, when the illumination pattern 13 is moved in the scanning direction by four frames and returned to the position of the initial frame, each frame may be drawn as follows.
That is, for each line (nth line) of the initial frame, assume that divided images B1 to B4 are obtained by dividing the image B for one period from the leading end into four, and the images corresponding to these divided images B1 to B4 are set from the rear, An illumination pattern is drawn by sequentially adding to the tip of the same line in each frame. The width of each of the divided images B1 to B4 is the interframe shift amount s.

Specifically, as shown in FIG. 7, an image corresponding to the first divided image B1 (width s) from the rear is added to the tip of the same line (nth line) in the second frame, The illumination pattern 13 is drawn, and similarly, in the third frame, an image corresponding to the second divided image B1+B2 (width 2s) from the back is added, and in the fourth frame, the third divided image B1+B2+B3 from the back is added. An image corresponding to (width 3s) is added, and in the fifth frame, an image corresponding to the fourth divided image B1+B2+B3+B4 (width 4s) from the back is added, and the illumination pattern 13 is drawn.

For the frame of the next cycle, that is, the sixth frame and thereafter, the moving illumination pattern 13 may be drawn by repeating the procedure from the second frame to the fifth frame shown in FIG. 7.

Further, as shown in FIG. 8, when the illumination pattern 13 is moved to the position of the initial frame by moving one cycle by the four frames in the direction opposite to the scanning direction, each frame is drawn as follows. Good.

That is, for each line (nth line) of the initial frame, assume that divided images B1 to B4 are obtained by dividing the image B for one period from the leading end into four, and the images corresponding to these divided images B1 to B4 are arranged from the front. Cut out and draw the same line in each frame.

Specifically, as shown in FIG. 8, in the same line (nth line) in the second frame, the image corresponding to the first divided image B4 (width s) is cut out and the illumination pattern 13 is drawn. To do. Similarly, in the third frame, an image corresponding to the second divided image B4+B3 (width 2s) from the front is cut out, and in the fourth frame, an image corresponding to the third divided image B4+B3+B2 (width 3s). In the fifth frame, the image corresponding to the fourth divided image B4+B3+B2+B1 (width 4s) from the front is cut, and the same line (nth line) is drawn.

From the frame of the next cycle, that is, the sixth frame and thereafter, the moving illumination pattern 13 may be drawn by repeating the procedure from the second frame to the fifth frame shown in FIG.

In the drawing method shown in FIGS. 7 and 8, the drawing method is shown in which the illumination pattern 13 is moved in the scanning direction by four frames, but one cycle is moved in the scanning direction by an arbitrary number of frames. It can also be moved. In that case, one cycle of the image from the tip may be divided into a number of images corresponding to the number of frames, and the divided images may be added or cut out for each frame, as in the above-described embodiment. ..

It is also possible to draw an image in which the lighting pattern 13 moves intermittently by appropriately inserting a frame for drawing the stationary lighting pattern 13 between each frame for drawing the moving lighting pattern 13. ..

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various application examples and modified implementations are possible as necessary.

1: Illumination device, 2: Imaging device, 3: Computer, 4: Inspection target,
10: Liquid crystal drawing unit, 11: Backlight, 12: FPGA (control device), 13: Illumination pattern, 13a: White band (light band), 13b: Black band (dark band), 14: Drawing area , 15: non-drawing area,
20: video timing generation unit, 21: illumination pattern generation unit,
A: offset part, B: image for one cycle from the beginning, B1, B2, B3, B4: divided images

Claims (5)

The surface of the inspection target is irradiated with pattern illumination in which bright strips and dark strips of different brightness are alternately arranged, and the image obtained by imaging the surface of the inspection target is used. Built into the surface inspection device that inspects the condition,
A surface inspection illumination device for irradiating the surface of the inspection object with the pattern illumination,
A drawing unit that draws an illumination pattern in which the bright strips and the dark strips are arranged alternately by a raster scanning method; and a control device for drawing the illumination pattern on the drawing unit,
The control device constitutes a processing circuit that sequentially calculates drawing data for each scanning line for drawing the illumination pattern in the drawing unit according to a drawing parameter set in advance, and An illumination device for surface inspection, wherein the illumination pattern is drawn on the drawing unit according to drawing data for each scanning line. The control device is
As the drawing parameter, the width dimension in the scanning direction of the bright strip-shaped portion forming the illumination pattern, the width dimension in the scanning direction of the dark strip-shaped portion, and each for drawing the respective strip-shaped portions with inclination The shift amount in the scanning direction of each strip portion for each scanning line is preset,
The drawing data for each scanning line for drawing the illumination pattern on the drawing unit is sequentially generated based on the drawing parameter including each of these set values. Lighting device for surface inspection. The control device is
As the drawing parameter, a value obtained by converting the shift amount for moving the strips in the width direction in the scanning direction is set in advance,
The surface inspection according to claim 2, wherein drawing data for each scanning line for drawing the illumination pattern on the drawing unit is sequentially generated based on the drawing parameter including the set value. Lighting equipment. The illumination device for surface inspection according to claim 1, wherein the control device is configured by an FPGA. A surface inspection device comprising the surface inspection illumination device according to claim 1 incorporated as a light source.

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