JP4289893B2 - Appearance measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an appearance measuring apparatus using a phase shift method, and in particular, determines whether or not a printed board on which automobile parts, semiconductor electronic parts and other electronic parts are mounted, or cream solder printed on the printed board, etc. The present invention relates to an appearance measuring apparatus. In addition, the phase shift method used in the present invention is to capture a plurality of light pattern images obtained by shooting images of a plurality of light patterns while changing the phase of the striped light pattern by one period (-π to π). This is a known method for obtaining a phase distribution from an image. The height information of the measurement object can be obtained from this phase distribution.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, various appearance measuring apparatuses that measure the appearance of a three-dimensional measurement object using a phase shift method have been proposed (see, for example, Patent Document 1).
[0003]
These apparatuses are photographed by an irradiation device that irradiates a measurement target with a striped light pattern, a photographing device that photographs an image of the measurement target irradiated with the striped light pattern, and the photographing device. And an arithmetic unit that calculates the external shape of the measurement object based on the image. Of these, a line sensor camera using a CCD (solid-state imaging device) image sensor or an area sensor camera, which is a known image processing apparatus, is usually used for the photographing apparatus, but has the following problems.
[0004]
When an area sensor camera is used, the imaging apparatus includes one area sensor camera, a moving grid for moving the light pattern is attached to the irradiation apparatus, and the imaging apparatus is moved by moving the light pattern relative to the measurement object. Since it is configured to take at least three images of the same part of the measurement object, the mechanical structure is complicated. In addition, in the area sensor camera, even in the case of the phase shift method in which processing can be performed with an image of a predetermined part of the measurement target, all images captured in the imaging range unnecessary for the inspection of the external shape of the measurement target are captured. Therefore, there is a problem that it takes time for photographing and calculation processing.
[0005]
On the other hand, the line sensor camera captures only the part necessary for the appearance inspection of the measurement object, and does not capture an unnecessary image for the inspection of the appearance shape of the measurement object unlike the area sensor camera, so the calculation processing time is shortened. . However, as its configuration, for example, the imaging apparatus includes at least three line sensor cameras, and the imaging apparatus captures at least three images of the same part of the measurement object by moving the measurement object with respect to the light pattern. The imaging apparatus includes one special line sensor camera that can capture at least three images with the same sensitivity, and the imaging apparatus moves by moving the measurement object with respect to the light pattern. Since it is configured to capture at least three images of the same part of the measurement object, the structure of the line sensor camera body is complicated. In order to improve measurement accuracy, it is desirable to install more line sensor cameras to obtain more images. However, the mechanical structure becomes complicated, and four or more images can be obtained with the same sensitivity. Since there is no one line sensor camera that can shoot, there is a problem that the number of installed line sensor cameras is limited and it is difficult to obtain high measurement accuracy.
[0006]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an appearance measuring device having a simple structure and capable of performing highly accurate measurement.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-81924 (4-5, FIG. 1)
[0008]
[Means for Solving the Problems]
In order to solve the above problems, an external appearance measuring apparatus according to the present invention is a light pattern irradiating unit that irradiates a surface of a measurement object with a striped light pattern in which the intensity of light periodically changes; At least three shooting ranges extending in a direction intersecting with the direction in which the relative positional relationship is changed at intervals of a period different from the period of the light pattern are set, An imaging unit that captures an image of the measurement object irradiated with the light pattern from the light pattern irradiation unit, and a displacement unit that changes a relative positional relationship between the measurement object and the light pattern. And above Calculating means for calculating height information of each part of the measurement object by a phase shift method based on an intensity distribution of light on an image corresponding to the imaging range captured by the imaging means; Preparation The light pattern irradiating means is configured to irradiate light patterns having different periods in the first half part and the second half part in the relative movement direction of the measurement object and the light pattern. Phase calculating means for calculating the phase of the light pattern of the period of the first half part and the latter half part based on an image photographed by the photographing means, and phase connecting means for connecting each phase calculated by the phase calculating means The phase connecting means is configured to connect each phase of the light pattern of the other period while referring to each phase of the light pattern of the other period. .
[0009]
According to this configuration, at least three light patterns having different intensities (phases) of light with respect to the same part of the measurement target necessary for the phase shift method are irradiated simply by changing the setting of the photographing range of the photographing unit. An image can be obtained. Therefore, when the appearance measuring apparatus according to the present invention is used, the structure is not complicated as in the case of using a conventional line sensor camera. In addition, the number of shooting ranges can be easily increased by changing the setting of the shooting range of the shooting means. This makes it possible to obtain many images for the same part of the measurement object. And since the height of the measurement object is calculated based on these many images in the calculation means, the height information obtained thereby becomes highly accurate. For example, a CMOS (complementary metal oxide semiconductor) image sensor is used as the photographing means.
001 0 ]
The light pattern irradiating means is Irradiate light patterns having different periods in the first half and the second half in the relative movement direction of the measurement object and the light pattern. Configured to Have . In this configuration, when the amount of information obtained from one cycle of the light pattern of each cycle is the same, the resolution (measurement accuracy) of the height information by the short cycle light pattern among the light patterns having a plurality of cycles is a long cycle. Higher than the light pattern. Therefore, it is possible to interpolate height information with each other by combining these height information. Thereby, even if it is a measurement object of a complicated shape, the height of a measurement object can be measured accurately.
001 1 ]
The above calculation means Is the above Based on the image taken by the photographing means The first half and the second half Phase calculating means for calculating the phase of the light pattern of the period, and phase connecting means for connecting the respective phases calculated by the phase calculating means. Possess The phase connecting means is One of Other while referring to each phase of the light pattern of the period Direction Is configured to connect each phase of the light pattern with a period of Become .
001 2 ]
In this configuration, the phase of a light pattern with a long period (another period) is connected while referring to the phase of a light pattern with a short period (one period), or the period of a short period with reference to the phase of a light pattern with a long period The phases of the light patterns can be connected. Thereby, even if it is a measurement target object with a discontinuous part, such as a level | step difference, the phase connection of an optical pattern can be performed appropriately and the exact height information of a measurement target object can be calculated | required. This is because the phase of the light pattern of the long period is overlapped at the same time even if the phase of the light pattern of the short period overlaps at the step portion of the measurement object (so-called phase jump). By not.
[0013]
The light pattern irradiating means is configured to irradiate a light pattern in which the one period is an even multiple of the other period, and the phase connecting means bit-converts the intensity distribution of the light pattern in the one period. The first height gradation of the measurement object and the second height gradation of the measurement object obtained by bit-converting the intensity distribution of the light pattern of the other period, and the first height When the height gradation value is within the first predetermined value and the second height gradation is not an even number, 1 is added to the second height gradation, and the first height gradation is When the second predetermined value is not less than the second predetermined value and the second height gradation is not an odd number, 1 may be subtracted from the second height gradation. . The phase connecting means may be configured to synthesize the upper part of the bit string of the second height gradation with the bit string of the first height gradation. .
001 4 ]
The photographing range of the photographing means may be configured to be changeable according to the external shape of the measurement object. In this configuration, since the setting of the shooting range of the shooting means can be changed, it can be enlarged or reduced according to the measurement dimension of the measurement object. Therefore, even when measuring the height of a large object to be measured, the structure can be simplified since it can be handled by a single photographing apparatus. In addition, since it is possible to prevent photographing unnecessary for measurement in a small measurement object, it is possible to improve the processing speed of the calculation means.
001 5 ]
The displacement means may be configured to be able to displace the light pattern irradiating means and the photographing means relative to the measurement object, or to displace the measurement object relative to the light pattern irradiating means and the photographing means. As a result, the structure is simplified compared to the conventional case where a moving grating is attached to the light pattern irradiating means and the light pattern is moved relative to the measurement object. . Up The light pattern of the light recording pattern irradiating means may be configured such that the light intensity changes in a sine wave shape along the displacement direction of the displacement means. As a result, the calculation for obtaining the height information by the phase shift method can be simplified, and the processing speed of the calculation means can be increased.
[0016]
The calculation means further includes a first calculation processing table for calculating height information of the part from light intensity distributions on at least three images for the same part of the measurement object imaged by the imaging means. It may be configured. In this configuration, the height information of each part of the measurement object can be obtained by referring to the first calculation processing table. Accordingly, height information can be obtained quickly.
[0017]
The calculation means may further include a second calculation processing table for connecting each phase of the light pattern of another cycle while referring to each phase of the light pattern of one cycle. In this configuration, the phase connection can be accurately and quickly performed by referring to the second arithmetic processing table. Thereby, accurate height information can be obtained quickly.
[0018]
The calculation means further includes a determination means for determining the quality of the measurement object based on the height information of the measurement object calculated by the calculation means, and the determination means becomes a preset reference. Based on the difference between the height information of each part of the measurement object and the height information of each part of the measurement object calculated from the image obtained by photographing the measurement object to be inspected It may be configured to determine pass / fail.
[0019]
In this configuration, since the determination unit is provided, the quality of the measurement object can be easily determined. In addition, as height information of each part of the measurement object M serving as a reference, image information of the measurement object serving as a reference photographed in advance by the imaging apparatus, CAD (computer aided design) conversion data of the measurement object serving as a reference Alternatively, those previously calculated and set based on user input data or the like are used. Therefore, it is possible to very easily cope with a design change of the measurement object.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a block diagram showing a configuration of an appearance measuring apparatus according to an embodiment of the present invention.
This appearance measuring device includes a light pattern irradiating device 1 that irradiates a surface of a measurement object M with a striped light pattern P, and a measurement object M irradiated with the light pattern P from the light pattern irradiating device 1. An imaging apparatus 2 that captures an image, an arithmetic processing apparatus 3 that calculates to obtain height information of each part of the measurement object M by a phase shift method based on an image captured by the imaging apparatus 2, and a measurement object A displacement device T that changes the relative positional relationship between M and the light pattern P is provided.
[0022]
The displacement device T includes a table 4 on which the measurement object M is mounted, a drive mechanism 5 that linearly moves the table 4 in one direction (the arrow X direction in FIG. 1), and the drive mechanism 5. A motor 6 to be driven and a motor driving device 7 for supplying power to the motor 6 and driving it are provided.
[0023]
The table 4 is composed of a slider or the like supported horizontally by a linear guide (not shown). The drive mechanism 5 includes a ball screw or a belt, and is used for connecting the table 4 and the motor 6 to change the rotational operation of the motor 6 to linear movement of the table 4. Therefore, the measurement object M mounted on the table 4 can be linearly moved in one direction by driving the motor 6. It is desirable to use a servo motor or the like that can be easily positioned as the motor 6. The table 4 may be configured to be moved linearly by a linear motor.
[0024]
The light pattern irradiating device 1 is a lattice projector, and is a direction (indicated by an arrow L in FIG. 1) inclined by a predetermined angle in the moving direction of the measurement object M with respect to the normal direction of the surface of the table 4. The light pattern P is arranged to irradiate the surface of the measurement object M from obliquely above on the moving direction side of the measurement object M. The light pattern P is a laser interference fringe or the like.
[0025]
FIG. 2 shows an example of a light pattern irradiated on the table from the light pattern irradiation device. As shown in the figure, the light pattern P is arranged in a stripe shape in the moving direction of the measurement object M, and the whole is in the shape of an ellipse. Here, although the shape of the light pattern P is an elliptical shape, the shape is not limited to this. For example, it may be rectangular. Thereby, the range which irradiates the light pattern P can be expanded. In the striped light pattern P, a first light pattern PP1 having a period (pitch) P1 is formed in the rear half portion with respect to the moving direction of the measurement object M, and a period (pitch) is formed in the front half portion. A second light pattern PP2 of P2 is formed. Here, P2 = P1 × 8 is set. The reason for using the light patterns P having a plurality of periods P1 and P2 in this way is to obtain the shape with high accuracy even when the shape change of the measurement object M is large. Details will be described later.
[0026]
Here, although the light patterns P having two periods P1 and P2 are set, the light pattern P having one or more periods may be set according to the shape of the measurement object M. Specifically, for example, when the shape change of the measurement object M is gentle, the light pattern P of one cycle is used, and when the shape change of the measurement object M is abrupt (for example, when there is a step) ) Uses a light pattern P having a plurality of periods.
[0027]
Although not shown, the light pattern P is set so that the intensity of light changes in a sine wave pattern in one cycle in order to simplify the calculation of height information by the phase shift method.
[0028]
The photographing device 2 is arranged above the table 4 so as to face the table 4 and can photograph a predetermined photographing range 20 set in advance as shown in FIG. This imaging range 20 is appropriately set according to the shape of the measurement object M.
[0029]
Further, in this imaging range 20, there are at least three imaging ranges that are arranged at intervals different from the periods P1 and P2 of the light pattern and extend in a direction intersecting the moving direction of the measurement object M. Is set.
[0030]
And the imaging device 2 is comprised so that the same site | part on the surface of the measurement target object M may be image | photographed when the same site | part on the surface of the measurement target object M comes just under each imaging | photography range. Therefore, the imaging device 2 is configured to perform imaging for a preset number of times in synchronization with the movement of the measurement object M. Details will be described later. Thereby, at least three images in which different light patterns P are irradiated on the same part of the measurement object M can be taken.
[0031]
For example, a CMOS (complementary metal oxide semiconductor) image sensor is used as the imaging device 2 as described above. In this CMOS image sensor camera, since the photographing range can be set arbitrarily, the number of photographing ranges is not limited to three. Therefore, in order to improve the measurement accuracy of the external shape (height) of the measurement object M, it is possible to set more photographing ranges.
[0032]
The arithmetic processing device 3 includes an input unit 30, a calculation unit 31, a storage unit 32, and an output unit 33, which are connected via wiring. The arithmetic processing device 3 is connected to a count comparison device 8 that outputs a captured image capture start signal of the imaging device 2 and a positioning device 9 that determines the position of the table 4 via wiring. Further, a position sensor 9a for measuring the current position of the table 4 is attached to the motor 6 described above, and this position sensor 9a is connected to the positioning device 9 via wiring.
[0033]
The input unit 30 is connected to the imaging device 2 and the count comparison device 8, and receives image information from the imaging device 2 and image capture start information from the count comparison device 8. The input unit 30 incorporates an arithmetic processing table 30a composed of logic circuits. The calculation processing table 30a has a function of calculating to obtain height information of each part of the measurement object M based on image information from the imaging apparatus 2. Furthermore, the input unit 30 is connected so that the height information obtained from the calculation processing table 30a can be output to the calculation unit 31. Although the input unit 30 includes the arithmetic processing table 30a here, the arithmetic processing table 30a may be provided in the storage unit 32.
[0034]
The arithmetic unit 31 is configured mainly with a microprocessor, and the storage unit 32 includes a read-only memory (ROM) and a random access memory (RAM), and a program that defines the operation procedure of the arithmetic unit 31 or the arithmetic unit 31. Store the data to be processed by.
[0035]
The calculation unit 31 transmits the movement position and movement speed of the table 4 stored in advance in the storage unit 32 to the positioning device 9 via the output unit 33 in order to synchronize the movement of the measurement object M and the photographing of the photographing device 2. Is configured to do. The positioning device 9 is configured to transmit the received movement position of the table 4 to the motor driving device 7. As a result, the motor driving device 7 drives the motor 6 based on the moving position and moving speed of the table 4 from the positioning device 9, whereby the table 4 is moved in one direction via the driving mechanism 5.
[0036]
At the same time, the calculation unit 31 transmits the image capture start position stored in advance in the storage unit 32 to the count comparison device 8 via the output unit 33 in order to synchronize the movement of the measurement object M and the imaging of the imaging device 2. Is configured to do. The count comparison device 8 compares the image capture start position with the current position of the moving table 4 transmitted from the position sensor 9a through the positioning device 9, and the current position of the table 4 is captured. When it coincides with the start position, image capture start information is output to the input unit 30. Thereby, the calculating part 31 makes the input part 30 start taking in the image information from the imaging device 2 based on the said image taking-in start information.
[0037]
As described above, the movement of the measurement object M and the photographing of the photographing apparatus 2 are synchronized, thereby associating a predetermined part on the surface of the measurement target M with the photographed image information.
[0038]
The calculation unit 31 compares the height information of each part of the measurement target M from the calculation processing table 30a with the height information of each part of the measurement target M serving as a reference, and compares these differences. Whether the measurement object M is good or bad is determined based on whether or not exceeds a predetermined value. The determination result is displayed on a display device (not shown). Note that the height information of each part of the measurement object M serving as a reference includes image information of the measurement object M serving as a reference, which has been imaged in advance by the imaging apparatus 2, and CAD (computer-aided design) of the measurement object serving as a reference. It is calculated based on the conversion data or user input data, and is stored in the storage unit 32.
[0039]
The operation of the appearance measuring apparatus configured as described above will be described with reference to FIGS. In this embodiment, it is assumed that the arithmetic processing unit 3 used in the appearance measuring apparatus can process 8-bit (256 pieces) of height information. However, this information amount is appropriately set according to the accuracy of measuring the external shape of the measurement object M, the measurement processing speed, the facility cost, etc., and is not limited to this numerical value.
[0040]
FIG. 3 is a side view schematically showing a state in which the measurement target is irradiated with the light pattern from the light pattern irradiation apparatus. As shown in the figure, first, light patterns P (see FIG. 2) having two periods P 1 and P 2 different from those of the light pattern irradiating apparatus 1 are predetermined in the moving direction of the measurement object M with respect to the normal direction of the surface of the table 4. The measurement object M is irradiated from the direction inclined by the angle α. As described above, the different periods P1 and P2 are set to P2 = P1 × 8. Specifically, for example, if P1 = 1 mm, then P2 = 8 mm. Here, although P2 = P1x8 is set, it may be set to an even multiple between P2 = P1x2 and P2 = P1x128 according to the shape of the measurement object M. This point will be described later.
[0041]
When the imaging device 2 is located directly below each preset imaging range 20 (see FIG. 2), the same part on the surface of the measurement object M that moves in one direction (X direction in FIG. 1) by the displacement device T. The same part on the surface of the measuring object M is imaged. For example, when the measurement object M having a width of 200 mm and a length of 200 mm is measured, the imaging range 20 is set to a width of about 220 mm and a length of about 20 mm. Therefore, in the first light pattern PP1 having the period P1 (1 mm), 20 periods are simultaneously imaged by the imaging device 2. In the second light pattern PP2 having the period P2 (8 mm), two periods are simultaneously photographed by the photographing apparatus 2. Actually, only the image necessary for the calculation of the height information by the phase shift method is appropriately selected from the images captured by the imaging device 2 in this way, and the height of the measurement object M is calculated based on the image. Is done.
[0042]
Further, the photographing range is set to be different from the periods P1 and P2 of the first and second light patterns PP1 and PP2. As described above, the phase shift method requires an image irradiated with the light pattern P of at least three light intensities on the same part of the measurement object M. For example, this imaging range is obtained for one period of the light pattern P. Are set at intervals of 0.25 mm for the first light pattern PP1 with P1 = 1 mm, and are set at intervals of 2 mm for the second light pattern PP2 with P2 = 8 mm. And the imaging device 2 images the image on the surface of the measurement object M corresponding to each imaging range.
[0043]
Note that the above-described imaging range is an example, depending on the shape of the measurement object M, the number of periods of the light pattern, the number of images irradiated with light patterns having different light intensities on the same part of the measurement object M, and the like. Set as appropriate.
[0044]
An image photographed by the photographing device 2 is input to the input unit 30 as image information. Then, the calculation processing table 30a of the input unit 30 calculates to obtain the height information (height) of the measurement object M by the phase shift method based on the image information.
[0045]
Referring to FIG. 3, the height H1 of the measurement object M can be obtained from the following equation (Equation 1).
[0046]
[Expression 1]
tan α = D1 / H1
Note that D1 indicates that the stripes of the first and second light patterns PP1 and PP2 are moved in the moving direction of the measurement object M (FIG. 5) depending on whether or not the measurement object M is irradiated with the first and second light patterns PP1 and PP2. 3 (the amount of displacement corresponding to the phase shift between the first and second light patterns PP1 and PP2). This displacement amount D1 is obtained by the phase shift method. Α is an irradiation angle of the first and second light patterns PP1 and PP2 with respect to the normal direction of the surface of the table 4.
[0047]
From the above, in (Equation 1), for example, when α = 45 °, the measurable heights H1max and H2max corresponding to the periods P1 and P2 of the first and second light patterns PP1 and PP2 are as follows. It becomes equal to the periods P1 and P2, respectively. The reason is that the limit displacement D1 where the adjacent stripes of the first and second light patterns PP1 and PP2 overlap is the respective periods P1 and P2, and the first and second light patterns PP1 and PP1 that have been displaced beyond this limit P1 and P2, respectively. This is because it is impossible to distinguish which stripe before PP2 is displaced. Specifically, when P1 = 1 mm, H1max = P1 and H1max = 1 mm. Similarly, when P2 = 8 mm, H2max = P2 and H2max = 8 mm.
[0048]
Further, the resolution of the height information in this case is that the arithmetic processing unit 3 can process 8 bits (256 pieces) of height information for one period of the light pattern P. The resolution H1res of PP1 is H1res = H1max / 256 = 3.90625 micrometers. Similarly, the resolution H2res of the second light pattern PP2 is H2res = H2max / 256 = 31.25 micrometers.
[0049]
As described above, when the measurement object M is irradiated with the first light pattern PP1, the measurable height H1max corresponding to this is small, but the resolution is high. As a result, when the change amount of the actual height of the measurement object M is larger than the period P1 of the first light pattern PP1, that is, the measurable height H1max, the displacement amount D1 is also measurable height H1max as described above. Therefore, one stripe of the first light pattern PP1 exceeds the period P1 and is largely displaced in the moving direction of the measurement object M and overlaps with the other stripes. Thereby, the exact height of the measuring object M cannot be obtained. On the other hand, when the measurement object M is irradiated with the second light pattern PP2, the measurable height corresponding to the second light pattern PP2 is large, but the resolution is lowered instead. Therefore, it is possible to grasp the change in the overall external shape of the measurement object M, but it is not possible to obtain a highly accurate measurement result. Therefore, in the present embodiment, by combining the first and second light patterns PP1 and PP2, a change in the overall shape of the measurement object M is grasped using the second light pattern PP2, and the first light pattern PP1 is used. To improve measurement accuracy. This will be described in more detail below.
[0050]
Fig.4 (a) is a figure which shows an example of the result obtained by measuring the height of one site | part of the measuring object M using the external appearance measuring apparatus which concerns on one Embodiment of this invention. In the figure, the horizontal axis represents the first height gradation H1hex and the second height gradation H2hex of the measurement object M corresponding to the periods P1 and P2 of the first and second light patterns PP1 and PP2, respectively. The first and second height gradations H1 hex and H2 hex are obtained from the displacement amount D1, respectively, and the intensity distribution of light in one period (−π to π) of the first and second light patterns PP1 and PP2. Is a value (0 to 255) converted to 256. The vertical axis represents the height of the measurement object M.
[0051]
As shown in FIG. 4A, the height H12 of the measurement object M corresponding to the first light pattern PP1 repeatedly changes with respect to the moving direction of the measurement object M between 0 and 1 mm. Further, the corresponding first height gradation H1hex also repeatedly changes with respect to the moving direction of the measuring object M between 0 and 255. On the other hand, the height H13 of the measurement object M corresponding to the second light pattern PP2 changes with respect to the moving direction of the measurement object M between 0 and 8 mm. Further, the second height gradation H2hex corresponding to this also changes with respect to the moving direction of the measuring object M between 0 and 255.
[0052]
Note that, here, only one period P2 of the second light pattern PP2 is shown, but the height H13 of the measurement object M corresponding to the second light pattern PP2 is also 0 to 0 as in the first light pattern PP1. The second height gradation H2hex corresponding to the moving direction of the measuring object M repeatedly changes between 8 mm and the second height gradation H2hex corresponding to this. Here, a case where the height of the measuring object M increases monotonously is shown.
[0053]
FIG. 4B is an enlarged view of a range BB indicated by a broken line in FIG. The height H12 of the measurement object M corresponding to the first light pattern PP1 increases as the first height gradation H1hex increases. When the first height gradation H1hex becomes 255, the height H12 of the measurement object M becomes 1 mm, and beyond this, the first height gradation H1hex becomes 0 and the measurement object M becomes high. The height H12 is also 0 mm. However, since the height H13 of the measurement object M corresponding to the second light pattern PP2 corresponding to the second light pattern PP2 is larger than the first light pattern PP1, the measurable height H2max of the second light pattern PP2 is larger than the first light pattern PP1. Unlike PP1, it does not become 0 mm, but becomes the actual height of the measurement object M. Accordingly, referring to the height H13 of the measurement object M corresponding to the second light pattern PP2, the height H12 of the measurement object M corresponding to the first light pattern PP1 for each period is accurately connected (phase connection). Thus, the accurate height of the measurement object M can be obtained. Thus, in order to obtain an accurate height of the measurement object M, it is important that an accurate phase connection is performed. More specific description will be given below.
[0054]
FIG. 5 shows first and second height gradations corresponding to the height of the measurement object M (for example, 0.01, 0.98, 0.99, 1.00, 1.01 and 7.99 mm). It is a figure which shows the calculation result of. As shown in the figure, in the case of only the first height gradation H1 hex, the first height gradation H1 hex corresponding to the height H12 of the measurement object M of 0.01 mm and 1.01 mm are both 2 and are distinguished. Not attached. However, if the result of the second height gradation H2hex is reflected in this result, the second height gradation H2hex corresponding to the height H12 of the measurement object M of 0.01 mm and 1.01 mm becomes 0 and 32, respectively. It becomes possible to distinguish. In this way, accurate phase connection (the height H12 of the measurement object M is changed from 1.00 mm to 1.01 mm instead of 0.01 mm) is performed. As a result, the exact height of the measurement object M is required.
[0055]
Further, when an error occurs during the measurement of the height of the measurement object M, the height H13 of the measurement object M is 0.99 mm, the first height gradation H1hex = 253, and the second height gradation H2hex = Even in the case of 32, the correct second height gradation H2hex can be obtained based on the first height gradation H1hex. Details will be described later. Thereby, the accurate phase connection of the second height gradation H2hex is performed, and as a result, the accurate height of the measurement object M is obtained.
[0056]
Next, the above process will be described more specifically with reference to FIG. FIG. 6 is a flowchart for calculating the height of the appearance measuring apparatus according to the embodiment of the present invention.
[0057]
The imaging device 2 images the measurement object M (S1). Based on the image information input from the photographing apparatus 2 to the input unit 30, the arithmetic processing table 30a calculates the displacement amount D1 shown in (Expression 1) (S2, S4). In step S2, a displacement amount D1 corresponding to the first light pattern PP1 is calculated. In step 4, a displacement amount D1 corresponding to the second light pattern PP2 is calculated. Thereafter, the first and second height gradations H1hex and H2hex are calculated from the respective displacement amounts D1 (S3, S5).
[0058]
Thereafter, it is determined whether or not H1hex> 5 (S6). If H1hex> 5 is not satisfied in step S6, it is determined whether or not the second height gradation H2hex is an even number (S7). In step S7, if the second height gradation H2hex is not an even number, it is replaced with H2hex = H2hex + 1 (S8). If the second height gradation H2hex is an even number, the number is processed as it is in step S12. The If H1hex> 5 in step S6, it is determined whether H1hex <250 (S9).
[0059]
In step S9, if the first height gradation H1hex <250 is not satisfied, it is determined whether or not the second height gradation H2hex is an odd number (S10). In step S10, if the second height gradation H2hex is not an odd number, it is replaced with the second height gradation H2hex = H2hex-1 (S11). If the second height gradation H2hex is an odd number, it remains unchanged. The number is processed in step S12. In step S9, if the first height gradation H1hex <250, H2hex having higher accuracy in the first height gradation H1hex and the second height gradation H2hex is generated in step S12. . According to the above steps S6 to S11, for example, an error occurs during measurement of the height of the measurement object M described above, so that the height H13 of the measurement object M is 0.99 mm and the first height gradation. Even when H1hex = 253 and the second height gradation H2hex = 32, the first height gradation H1hex = 253 (S9) and the second height gradation H2hex is an even number (S10). Thus, the second height gradation H2hex = H2hex−1 (S11), and the correct second height gradation H2hex = 31 (see FIG. 5) can be derived.
[0060]
In step S12, the first height gradation H1hex (8 bits) and the second height gradation H2hex (8 bits) are combined to obtain the second height gradation H2hex (11 bits). In this case, since the same term of the first height gradation H1hex (8 bits) and the second height gradation H2hex (8 bits) is 5 bits, the upper 3 bits of the second height gradation H2hex are the first high. This is different from the gradation H1 hex. As a result, the first height gradation H1hex (8 bits) and the second height gradation H2hex (3 bits) are combined, and the second height gradation H2hex becomes 11 bits. Then, the height of the measurement object M is calculated based on the height gradation H2hex (11 bits) obtained in step S12. As a result, high-precision height information is obtained as compared to the height information of the measurement object M based on 8-bit information. Here, the case where the relationship between the different periods of the light pattern P is P2 = P1x8 is shown, but when P2 = P1x128, the first height gradation H1hex (8 bits) and the second height Since the same term of the gradation H2hex (8 bits) is 1 bit, when these are combined, a second height gradation H2hex of 15 bits is obtained.
[0061]
Steps S2 and S4 constitute phase calculation means, and steps S3, S5, S6 to S1. 2 Constitutes phase connecting means. The arithmetic processing table 30a constitutes a first arithmetic processing table.
[0062]
The phase connecting means may be replaced with a second calculation processing table. As a result, the calculation processing speed can be improved.
[0063]
In addition, since there is a step of determining whether the second height gradation is an even number or an odd number in steps S6 to S11 described above, the relationship between the periods P1 and P2 is an even multiple of the other period with respect to one period. It is said. Therefore, when the amount of information is 8 bits (256), the period P2 is adjusted between P2 = P1x2 and P2 = P1x128. Of course, when the amount of information is not 8 bits, it is set based on the amount of information. For example, when the amount of information is 4 bits (16 pieces), the amount is adjusted between P2 = P1x2 and P2 = P1x8.
[0064]
Further, the arithmetic processing device 3 compares the height information of each part of the measurement object M calculated as described above with the height information of each part of the measurement object M serving as a reference. The quality of the measurement object M is determined based on whether or not the difference between the two exceeds a predetermined value.
[0065]
【The invention's effect】
According to the present invention, the structure is simple and highly accurate measurement can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an appearance measuring apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a light pattern irradiated on a table from a light pattern irradiation device.
FIG. 3 is a side view schematically showing a state in which a measurement object is irradiated with a light pattern from the light pattern irradiation device.
FIG. 4 is a diagram illustrating an example of a result obtained by measuring the height of a measurement object using the appearance measuring device according to the embodiment of the present invention.
FIG. 5 is a diagram showing calculation results of first and second height gradations corresponding to the height of a measurement object.
FIG. 6 is a flowchart for calculating the height of a measurement object by an appearance measuring apparatus according to an embodiment of the present invention.
[Explanation of symbols]
1 Light pattern irradiation device
2 Shooting device
3 arithmetic processing unit
4 tables
5 Drive mechanism
6 Motor
7 Motor drive device
8 Count comparison device
9 Positioning device
9a Position sensor
M Measurement object
P light pattern
T displacement device
30a arithmetic processing table

Claims (8)

A light pattern irradiating means for irradiating the surface of the measurement object with a striped light pattern in which the intensity of light periodically changes;
The measurement object in which at least three imaging ranges extending in a direction intersecting with the direction in which the relative positional relationship is changed at intervals of a period different from the period of the light pattern are set and irradiated with the light pattern from the light pattern irradiation unit Photographing means for photographing an image of an object;
Displacement means for changing a relative positional relationship between the measurement object and the light pattern ;
At least three photographed by the photographing means, a calculating means for calculating to obtain height information of each part of the measurement object by the phase shift method based on the intensity distribution of the light on the image corresponding to the photographing range equipped with a,
The light pattern irradiating means is configured to irradiate light patterns having different periods in the first half part and the second half part in the relative movement direction of the measurement object and the light pattern,
The calculation means connects the phase calculation means for calculating the phase of the light pattern of the period of the first half part and the latter half part based on the image photographed by the photographing means, and each phase calculated by the phase calculation means And a phase connecting means configured to connect each phase of the light pattern of the other period while referring to each phase of the light pattern of the one period. . The light pattern irradiation means is configured to irradiate a light pattern in which the one cycle is an even multiple of the other cycle,
The phase connecting means is
The first height gradation of the measurement object obtained by bit conversion of the intensity distribution of the light pattern of the one period and the second height gradation of the measurement object obtained by bit conversion of the intensity distribution of the light pattern of the other period. And, and
When the value of the first height gradation is within the first predetermined value and the second height gradation is not an even number, 1 is added to the second height gradation and the first height gradation is added. 2. The appearance measuring device according to claim 1 , wherein when the height gradation is equal to or greater than a second predetermined value and the second height gradation is not an odd number, 1 is subtracted from the second height gradation. . 3. The appearance measuring apparatus according to claim 2 , wherein the phase connecting means is configured to synthesize an upper part of the bit string of the second height gradation with the bit string of the first height gradation . The said displacement means is comprised so that the said measurement target can be displaced with respect to the said measurement target object with respect to the said light pattern irradiation means and imaging | photography means, or the said light pattern irradiation means and imaging | photography means. The appearance measuring device according to any one of 1 to 3 . The appearance measuring apparatus according to any one of claims 1 to 4 , wherein the light pattern of the light pattern irradiating means is configured so that the intensity of light changes sinusoidally along the displacement direction of the displacing means. The calculation means further includes a first calculation processing table for calculating height information of the part from light intensity distributions on at least three images for the same part of the measurement object imaged by the imaging means. becomes, the appearance measuring device according to any one of claims 1 to 5. The external appearance according to claim 5 or 6 , wherein the arithmetic means further includes a second arithmetic processing table for connecting each phase of the light pattern of another cycle while referring to each phase of the light pattern of one cycle. Measuring device. The calculation means further comprises a determination means for determining the quality of the measurement object based on the height information of the measurement object calculated by the calculation means,
The determination means includes the height information of each part of the measurement target serving as a reference that is set in advance, and each part of the measurement target calculated from an image obtained by photographing the measurement target to be inspected. The appearance measuring device according to any one of claims 1 to 7, wherein the appearance measuring device is configured to determine whether or not the measurement object is good based on a difference from the height information.

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