JPS63286702A - Method for measuring residual thickness of groove - Google Patents

Abstract

PURPOSE:To measure the residual thickness of a groove with high accuracy without using a tracer, by providing first and second TV cameras provided with a microscope lens. CONSTITUTION:A video signal Va1 and Va2 obtained from a TV camera 12A and 12B are inputted to first and second binary pulse generating means 22A, 22B, respectively. Binary pulses obtained from the binary pulse generating means 22A, 22B are inputted to the first and the second binary pulse counting means 23A, 23B, respectively, and counted. Also, a driving pulse Vp given to a pulse motor 17 from a pulse power source 20 is inputted to a driving pulse counting means 24, and outputs of the counting means 23A, 23B, and the driving pulse counting means 24 are inputted to an arithmetic processor 21. Subsequently, the arithmetic processor 21 controls the pulse power source 20 and each pulse counting means 23A, 23B in accordance with a control algorithm, and also, executes an operation for deriving the residual thickness of a groove. In such a way, the residual thickness of the groove can be measured with high accuracy without using a tracer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for measuring the remaining thickness of a groove provided on the surface of an object (the thickness at the bottom of the groove).

[Prior Art] There is a lifting platform that is required to measure the remaining thickness of grooves formed on the surface of an object during product inspection on a factory production line.

For example, in pull-top can lids, the remaining thickness of the groove (score) that defines the part that is cut off when the tab is pulled up (score residual) is called the SR value and is strictly controlled by υ. FIG. 13 shows a pull-top type can lid 1, which includes a disc-shaped panel portion 100, etc.
It consists of a rivet part 101 formed by extruding the center part of 00 to the outside, and a tab 102 fixed to the panel part 100 by the rivet part. A predetermined shape 1103 is formed on the panel portion 100, and the tab 10
2, the inner part of the filler 103 is cut off at the groove 103 to form an opening in the can lid.

An enlarged view of the Fi 103 portion of the can lid above shows the first
As shown in Figure 4, if the remaining thickness Xt of the groove 103 is larger than the specified value, the inner part of the groove 103 cannot be cut out, and if the remaining thickness Xt is smaller than the specified value, the pressure resistance of the can lid will be reduced. It is dangerous because it has deteriorated.

Therefore, on a line that manufactures this type of can lid, can lids 1 are handled at a certain rate from the line, the remaining thickness of the groove 103 is measured, and it is checked whether the remaining thickness of the groove is within a specified range. There is a need.

Conventionally, as a method for measuring the remaining thickness of a groove, the tactile method, in which a tactile button is inserted into the groove, has been used.

However, when the width is very narrow, such as the groove 103 provided in a can lid, the stylus 2 is inserted into the groove 1 as shown in FIG.
03 and a gap ε is created between the tip of the stylus 2 and the bottom of the groove 103, making it impossible to measure. Therefore, in the can lid, a dummy score 104 (see Fig. 13) into which a stylus can be inserted is formed at the same time as the groove 103 is formed by press working, and the remaining thickness of this dummy score is measured. groove 1
A method of controlling the remaining thickness of 03 was used.

[Problems to be Solved by the Invention] Conventionally, when measuring the remaining thickness of a narrow groove such as a groove on a can lid, it was necessary to provide a dummy score and measure the remaining thickness of the dummy score. Therefore, the original residual thickness of the groove could only be managed indirectly, resulting in a problem of poor reliability. Furthermore, when using the stylus method, the accuracy of measurement depends on the skill of the measurer, so there is a problem in that the measurement requires skill. Furthermore, the area of the tip of the stylus is very small, and when the stylus is inserted into the groove, the force per unit area that acts on the bottom of the groove is large. There is also a problem that the stylus may become wedged in the bottom of the groove, increasing measurement errors.

The present applicant previously stated in Japanese Patent Application No. 61-73822,
We proposed a method to measure the unevenness of the surface of an object with high precision using a television camera equipped with a microscope lens. According to this method, the unevenness of the surface of an object can be measured without contact, and even when the width of the groove is narrow, the depth can be measured. However, the method proposed earlier was not able to measure the remaining thickness of the groove.

An object of the present invention is to propose a method for measuring the remaining thickness of a groove by using a television camera to measure the remaining thickness of the groove with high precision without using a touch i1.

[Means for solving the problem 1 In the invention of Application 1, first and second microscope lenses are provided with microscope lenses adjusted to focus on an object at a position separated by a set distance 1. Place the television cameras facing each other with the optical axes of their lenses aligned, and
and means for obtaining first and second 21+rj pulses by differentiating the first and second video signals respectively received from the second television camera and comparing them with a predetermined threshold level. .

First, a block gauge having a known thickness is placed between the two television cameras and moved in the direction of the optical axis relative to both television cameras. Then, in the process of relative movement of the block gauge, the first and second binarized pulses are counted, and after the count value of one binarized pulse reaches the maximum, the count value of the other binarized pulse reaches the maximum. A value obtained by adding the thickness of the block gauge to the movement distance is determined as a constant determined by the distance between the lenses of the first and second television cameras.

This step of determining the constant may be performed at least once before measuring the object to be measured.

When measuring the remaining thickness of the groove of the object to be measured, the object to be measured is placed between both television cameras, and the optical axes of both television cameras pass through the bottom of the groove of the object to be measured. Then, the object to be measured is moved relative to both the television cameras. In the process of moving the object to be measured, the first and second binarized pulses are counted, and from the position where the count value of one binarized pulse is the maximum, the count value of the other binarized pulse is the maximum. The remaining thickness is determined by determining the moving distance to the position where the remaining thickness is measured as a residual thickness measurement variable, and subtracting the residual thickness measurement variable from the constant.

In the first aspect of the invention, the positional relationship between the first and second television cameras is always kept constant, and both television cameras, the block gauge, and the object to be measured are moved relative to each other. In the second aspect of the present invention, the block gauge and the object to be measured are fixed, and the first and second television cameras are moved respectively.

The second invention is similar to the first invention in that the optical axes of the first and second television cameras are made to coincide and that means for obtaining the first and second binarized pulses are provided.

In the second invention, first, a block gauge is placed between both television cameras, the block gauge is made to face both television cameras, and the first and second television cameras are moved to the first and second origin positions, respectively. Move it from there towards the block gauge.

Then, in the process of moving the first and second television cameras toward the block gauge, the first and second binarized pulses are counted, and the first binarized pulse is counted from the first origin position. The thickness of the block gauge is added to the sum of the moving distance to the position where the count value is maximum and the moving distance from the second origin position to the position where the word value of the second binarized pulse is maximum. Let the value be a constant determined by the distance between the lenses of the first and second television cameras.

When measuring the remaining thickness of the groove of the object to be measured, the object to be measured is placed between the first and second television cameras, and the object to be measured is faced to both television cameras. At the same time, the optical axes of both television cameras are made to pass through the bottom of the vortex of the object to be measured, and the first and second television cameras are directed toward the object to be measured from the first and second origin positions, respectively. and move it.

Then, in the process of moving the first and second television cameras toward the object to be measured, the first and second binarized pulses are counted and the first binarized pulses are counted from the first origin position. The movement distance until the count value reaches the maximum and the second
The remaining thickness of the groove is determined by subtracting the residual thickness measurement variable from the constant.

[Operation of the Invention] Generally, an image obtained by conveying an image of the surface of an object by a television camera becomes a sharp image with strong contrast as the lens focuses. Therefore, as the lens focuses, the image obtained from a television camera will contain more components with high spatial frequencies, and when the lens is in focus, the highest amount of components with high spatial frequencies will be present.

Therefore, by differentiating the video signals obtained by the first and second television cameras, extracting the high frequency components by 1q of the differential signals, and comparing the differential signals with a predetermined threshold level, 2 When the first and second binarized pulses are generated and these pulses are counted while moving the subject and the first and second television cameras relatively in the optical axis direction, the first and second binarized pulses are counted. Second
The count value of the binarized pulses becomes maximum at certain positions P1 and P2. Position P1 where the count value of these pulses is maximum
At P2, it can be considered that the lenses of the first and second television cameras are focused on the image portion of the subject. Hereinafter, these positions HP1 and P2 will be referred to as focus positions.

As in the first invention, when the first and second television cameras are arranged facing each other while maintaining a predetermined positional relationship, the focus positions P1 and P2 of both television cameras are constant, and both the focus positions P1 The distance between °12 is always constant.

As in the first invention, a block gauge with a known thickness is arranged between the first and second television cameras, and the block gauge and the first and second television cameras are relatively illuminated. Count the first and second binarized pulses while moving in the axial direction, from the position where the S1 value of one binarized pulse is maximum to the position where the counted value of the other binarized pulse is maximum. By calculating the moving distance and adding the thickness of the block gauge to the moving distance, the distance between the focus positions P1 and P12 can be found. In the first invention, this distance is a constant determined by the distance between the lenses of the first and second television cameras.

After determining the constant as described above, place the object between the first and second television cameras so that the optical axes of both television cameras pass through the bottom of the groove. While moving the camera and the television camera relative to each other,
and the second binarized pulse is counted, and the moving distance from the position where the count value of one binarization pulse is maximum to the position where the count value of the other binarization pulse is maximum is calculated as the residual thickness. By subtracting the measured variable from the above constant, the remaining thickness of the groove can be determined.

In the second invention, the distance between the focus positions P1.12 when the first and second television cameras are respectively at the first and second origin positions is a constant determined by the distance between the lenses of the television cameras, When the first and second television cameras are moved from the origin position toward the object to be measured, the sum of the moving distances to the position where the count value of the first and second pulses is maximum is the residual thickness. Becomes the measurement variable.

In this way, in the present invention, the remaining thickness of the groove of the object to be measured can be measured without contact using a television camera equipped with a microscope lens, so even if the width of the groove is narrow, it is possible to provide a dummy groove. The remaining thickness of the groove itself can be measured without any problems, and the remaining thickness of the groove can be appropriately managed. Furthermore, since the remaining thickness can be measured electrically, accurate measured values can be obtained without requiring the skill of the measurer.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 schematically shows an example of an apparatus for carrying out the first invention of the present application. 1 and 2 support stands, '12A and 12B are the first and second support stands supported by the first and second support stands, respectively.
television camera. The first and second television cameras 12A and 12B each have a microscope lens 1.
3A and 13B, and both television cameras are arranged to face each other with the optical axes 1a of these lenses aligned. Lenses 138 and 13B are adjusted so as to focus on objects located at focus positions P1 and P2, which are separated by a preset distance from both lenses.

A movable table 15 is arranged on the sides of the support tables 10Δ and 10B, and is moved by a feed screw 14 in a direction parallel to the optical axis of the television camera. The output shaft of a pulse motor 17 is connected to the feed screw 14 via a gear reduction mechanism 16.
The rotation of the pulse motor is decelerated and transmitted to the feed screw 14.

A jig for supporting the object to be inspected and the can M1 is attached to the moving table 15, and in the example shown in FIG.
is installed. The illustrated jig 18 has a hole into which the can lid 1 is fitted and a claw 19 that presses the can lid 1, and holds the can lid with the surface of the can lid 1 having the groove 103 orthogonal to the optical axis La. It is designed to be retained.

Although not shown, either the base 11 or the feed line including the moving table 15 and the feed screw 14 can be arbitrarily moved along a plane perpendicular to the optical axis 1a. A moving mechanism (for example, an It has become.

Reference numeral 20 denotes a pulse power supply that supplies drive pulses Vp to the pulse motor 17, and reference numeral 21 denotes an arithmetic processing unit' (CP
). The video signals va1 and Va2 obtained from the television cameras 12A and 12B are input to first and second binarized pulse generating means 22A and 22B, respectively, and the video signals 21il obtained from these binarized pulse generating means
The I-conversion pulses are input to first and second binarized pulse counting means 23A and 23B, respectively, and counted. Further, the drive pulse Vp given to the pulse Tanabata 17 from the pulse power supply is inputted to the drive pulse counting means 24, and the outputs of the counting means 23^, 23B and 24 are inputted to the arithmetic processing unit 21. The arithmetic processing unit 21 controls the pulse power source and each pulse counting means according to a control algorithm to be described later, and also performs calculations necessary to obtain the remaining thickness of the bulk.

As shown in FIG. 5, the binarized pulse generating means 228 includes a differentiating circuit 25 that differentiates the video signal Va1 obtained from the television camera 12A, and a differential signal obtained from the differentiating circuit 22^ to a predetermined threshold. 2 compared to the level
It also includes a binarization circuit 26 for converting into values.

The differentiating circuit 25 functions as a bypass filter and extracts high frequency components from the video signal. The binarization circuit 26 compares the differential signal with a threshold level, and when the differential signal exceeds the threshold level, generates a binarization pulse B.
Output pl. The configuration of the binary pulse generating means 22B is also similar, and the binary pulse Bp2 is obtained from the binary pulse generating means.

When the number of binarized pulses obtained in the above manner is counted over one field, the counted value will increase as the video signal contains more high frequency components, that is, the higher the contrast of the video. The higher it is, the bigger it becomes. Since the contrast of the image increases as the lens comes into focus, the count value of the binarized pulses becomes maximum when the lens focuses on the subject. In other words, the position where the lens is in focus on the subject can be detected by finding the position where the number of binarized pulses is maximum a.

The moving table 15 moves a unit distance each time one pulse is applied to the pulse motor 17. Take it to the table moving table 15 (-J G)
A drive pulse is started to be applied to the pulse motor 17 when the subject A is at a position Pa closer to the lens than the focus position P1, and when the subject passes the focus position P1 and reaches position pb, a driving pulse is supplied. Suppose you stop. In this case, each time each drive pulse is given, the binarization pulse is set to 1.
When counting is performed over the field, the distribution of the count value m is as shown in FIG. 6, for example, and the count value of the binarized pulse becomes maximum when the subject Δ reaches the pin 1 to the position P1. Here, the horizontal axis indicates the moving distance of the subject, and ΔX indicates the unit moving distance of the subject when a set number of drive pulses are applied to the pulse motor 17.

In the method of the present invention, two television cameras are used,
The remaining thickness of the groove of the object to be measured is directly measured using the above principle.

In the method of the present invention, the distance between the focus positions P1 and P2 of the two television cameras is set as a constant α, and the remaining thickness of the groove is measured based on this constant. Since the constant α differs depending on how the lens of each television camera is adjusted and how the television camera is installed, calibration work must be performed to accurately determine the constant before measuring the object to be measured. conduct. When performing this calibration work, move the moving table 15 as shown in Figure 2.
Attach block gauge 30 to. block gauge 30
is arranged with its plate surface perpendicular to the optical axis 1-a,
Both surfaces thereof are made to face lenses 13A and 13B of television cameras 12A and 12B.

FIG. 7 shows an example of the control algorithm for the arithmetic processing unit 210 when performing this calibration work.

When a calibration start command is given by a push button switch, etc.,
The arithmetic processing unit 21 gives a pulse output command to the pulse power source 20 to rotate the pulse motor and return the movable table 15 to the starting position. When the movable table 15 is at the start position, the first television camera side surface 30a of the block gauge 30 is located at the calibration start position Pa (see FIG. 3).

When it is confirmed that the moving table 15 is positioned at the start position, the output of the drive pulse is stopped and the count value of the drive pulse is reset to O. Here, the binarized pulse Bp1. which is obtained by binarizing the video signals obtained from the television cameras 12A and 12B. The number of BO2 is counted over one field, and each count value is stored together with the count value of the drive pulse ■p. Next, it is determined whether or not the drive pulse count (1α) has reached the set value, and when the drive pulse count does not reach the set value, the set number (moving table 15 is
The number of drive pulses required to move the object by X is output. This causes the pulse motor to rotate, and the block gauge 3
Unit distance ΔX from the 0 position in the X direction (direction parallel to the optical axis)
move only. Here, the binarized pulses Bp1 and BO2 are counted again over one field, and the counted values are stored together with the counted values of the drive pulses. Thereafter, similar operations are repeated until the count value of the drive pulse reaches the set value, and the world value of the binarized pulse and the count value of the drive pulse at each measurement position are stored. Here, as shown in FIG. 3, the set value of the count value of the driving pulse is such that the pulse is generated until the surface 30b of the block gauge on the second television camera 12B side passes the focus position P2 and reaches the measurement end position Pd. motor 17
Set it equal to the number of pulses you need to give.

Therefore, by the above operation, the block gauge moves by a unit distance ΔX in the .

After the count value of the drive pulse reaches the set value, the output of the drive pulse is stopped, and the stored binary pulses Bpl and 3p are output.
Sequentially compare the count values of 2 and find the count value of the driving pulse when the count value of each binarized pulse reaches the maximum,
After the digitization pulse Bpl reaches the maximum, the binarization pulse Bp
Block gauge movement stop until 2 reaches maximum 111X
By adding the thickness β of the block gauge to , the distance α between the focus positions I)d and P2 of the first and second television cameras is determined.

The video signal of the first television camera 12A is 2 (+
rt (the count value m of the first binarized pulse Bp1
When the video signal of the second television camera 12B is binarized (q), the distribution of the count value m2 of the second binarized pulse Bp2 is as shown in FIG. The count value m1 of the binarized pulse is 3 of the block gauge 30.
0a reaches the maximum when it reaches the focus position P1 of the first television camera, and the count value m2 of the second binarized pulse Bp2 reaches the maximum when the surface 30b of the 10 gauge 30 reaches the focus position P2 of the second television camera. It reaches its maximum when it reaches .

If the moving distance of the block gauge (obtained from the count value of the drive pulse) from the time when the surface 30a of the block gauge 30 reaches the focus position 1ffP1 until the surface 30b reaches the focus position P2 is defined as X, then the bin (・position Pi , P2 is given by α=X+β. This α is stored as a constant determined by the distance between the lenses of the television cameras 12^ and 12B.

Next, as shown in FIG. 1, the step of attaching the object to be measured 1 to the moving table 15 and measuring the remaining thickness of 103 is performed. At this time, the object to be measured 1 is placed with its 103 plane perpendicular to the optical axis 1a, and the object to be measured is placed so that the optical axis La passes through the bottom of the 103. 1 and the television cameras 12^ and 12B are adjusted in advance. Adjustment of this positional relationship may be performed manually while watching a television monitor, or may be performed automatically by calculating the maximum value of the binarized pulses. An example of a method for automatically adjusting the above-mentioned positional relationship using the example shown in FIG. 1 will be explained as follows.

After attaching the object to be measured 1 to the moving table 15, the surface of the object to be measured on which the groove 103 is provided is exposed to the television camera 1.
2B by a unit distance and store the count value of the binarized pulse Bp2 at each position. Then, the position where the counted value is maximum is determined, and the moving table 15 is stopped at the position. In this state, a certain point on the surface of the object to be measured 1 having the groove 103 is located at the focus position P2. Mobile platform 15
While moving C by a unit distance along a plane perpendicular to the optical axis 1a, repeat the same operation as above to obtain the surface shape of the surface having 2M 103 of the object to be measured 1, and from this surface shape, determine the bottom of the groove. Orient the location of.

In addition, when the position of the groove is fixed, the position of the groove can be always detected by mechanically positioning the object to be measured by identifying a specific part of the object to be measured as m < end). It can be matched to the axis position.

After the positioning of the object to be measured 1 is completed, the remaining thickness Xt is measured. An example of the control algorithm of the processing unit 21 at this time is shown in FIG.

That is, when a measurement start command is given, first the drive pulse Vp
is output, the pulse motor is rotated, and the moving table 15 is moved to the start position. At this time, the surface 1a of the object to be measured 1 on the first television camera side is at the measurement start position Pa.
(See Figure 4). After moving the movable table 15 to the start position, the output of the drive pulse is stopped, and the count value of the drive pulse is reset to O. Here, the 2Iil'i conversion pulse Bp1. which is obtained by binarizing the video signal obtained from the television camera 128, 12B. The number of Bo3 is counted over one field, and each count value is stored together with the 31 values of the drive pulse vp. Next, it is determined whether the count value of the drive pulse has reached the set value,
When the count value of the drive pulse is not equal to the set value, the set number of drive pulses (the number required to move the moving base by a unit distance) is output. As a result, the pulse motor is rotated, and the position of the object to be measured 1 is moved by a unit distance ΔX in the X direction (direction parallel to the optical axis). Here, the binarized pulses Bpl and BO2 are again counted over one field, and the counted fields are stored together with the counted values of the driving pulses. Thereafter, the same operation is repeated until the count value of the drive pulse reaches the set value, and the count value of the binarized pulse and the word value of the drive pulse at each measurement position are stored. Here, the set value of the count value of the driving pulse is set at the bottom surface 103a of the groove 103 as shown in FIG.
It is set equal to the number of pulses that must be applied to the pulse motor 17 until it exceeds the focus position flP2 and reaches the measurement end position Pd. Therefore, by the above operation, the object to be measured moves in the X direction by a medium distance Δχ,
Each time the object to be measured moves by a medium distance, the count value of the binarized pulse and the count value of the drive pulse are stored.

After the count value of the drive pulse reaches the set value, the output of the drive pulse is stopped and the stored binarized pulses 81) 1 and B
The count values m1 and 2 of o3 are compared sequentially, and each 2
Find the count value of the drive pulse when the count value of the digitization pulse reaches the maximum, and calculate the count value of the drive pulse when the count value of the digitization pulse 3p1 reaches the maximum.
The moving path lI× of the object to be measured until the valuation pulse Bf12 reaches the maximum is determined as a residual thickness measurement variable.

The distribution of the count value m1 of the first 2fa pulse Bp1 obtained by binarizing the video signal of the first television camera 12A and the second distribution obtained by binarizing the video signal of the second television camera 12B. For example, the distribution of the count value m2 of the binary pulse Bp2 is as shown in FIG. The count value m2 of the second binarized pulse Bp2 reaches its maximum when the camera reaches the focus position P1, and the count value m2 of the second binarized pulse Bp2 reaches the maximum when the bottom surface 103a of the groove of the object to be measured reaches the focus position P2 of the second television camera. become maximum. After the surface 1a of the object to be measured 1 reaches the focus position P1, the bottom surface 10 of the groove
3a reaches the focus position P2 (obtained from the count value of 9J pulses) by the residual thickness measurement variable X, then the remaining thickness of the groove) < 1 is
It is given by t=α−X.

Next, the invention of the second aspect of the present application will be explained in detail with reference to FIGS. 9 to 12. FIG. 9 shows a schematic configuration of an apparatus used to carry out the second invention. In this example, an object to be measured (a can lid) 1 is supported on a fixing table 31. As shown in FIG. The first and second television cameras 12^ and 12b are supported by movable platforms 32A and 32B, respectively, and both television cameras are supported by respective microscope lenses 13A and 13B.
are arranged facing each other with their optical axes 1a aligned. Feed screw 1 for moving the moving tables 31A and 32B, respectively
4A and 14B are provided, and these feed screws are connected to a pulse motor 17 via deceleration mechanisms 16A and 16B, respectively.
^ and connected to 17B. The pulse motors 17A and 17B are rotated by receiving driving pulses Vpl and VO2 from pulse power supplies 20^ and 20B controlled by the arithmetic processing unit 21. These driving pulses are counted by driving pulse counting means 24A and 24B.

Although not shown, a means (for example, an X-Y table) for moving the fixed base 31 along a plane perpendicular to the optical axis La is provided, and the moving means moves the object to be measured and the television camera. The positional relationship between the two can be adjusted. In other respects, the structure is similar to that of the embodiment shown in FIG.

Also in this second embodiment of the invention, the arithmetic processing unit 21 controls the pulse power source 20 and each pulse counting means according to a predetermined control algorithm, and performs the calculations necessary to determine the remaining thickness. Since the basic concept of the control algorithm of the arithmetic processing unit 21 in this case is the same as in the case of the previous embodiment, the description of the flow chart showing the control algorithm will be omitted, and only the operation will be described below.

In this embodiment as well, a calibration operation is first performed using a block gauge to determine a constant determined by the distance between the lenses of the television cameras 12A and 12B. When performing this calibration operation, the block gauge 30 is attached to the fixed base 31 as shown in FIG. Next, drive pulses are applied to the pulse motors 17A and 17B to move the movable tables 32A and 32B, and the first and second television cameras 12A and 12B are moved to the first and second origin positions, respectively. Shins 138 and 13 of both television cameras when the first and second television cameras are at the origin position
The focus positions of B are shown in FIG. 11 with reference numerals 01 and o2. Here, the count values of drive pulses Vp1 and Vp2 are reset to zero.

Next, the pulse power supplies 20^ and 20B each generate a set number of drive pulses to rotate the pulse motors 17A and 17B, and each time the set number of drive pulses are given, the video signals Va1 and ■a of the television cameras 12A and 12B are generated.
Binarized pulses Bp1 and B obtained by binarizing 2, respectively.
o3 is multiplied by il over one field, and the counted value is stored together with the counted value of the drive pulse (positions of the first and second preview cameras). The focus positions of lenses 138 and 13B are block gauge 30, so 30a and 30b
The generation of drive pulses VD1 and V112 is stopped when the drive pulses reach a position that has gone too far by a certain distance. The count value of the binarized pulses obtained in this way is determined when the focus positions of the lenses 13^ and 13B coincide with the surfaces 30a and 30b of the block gauge 30, as shown in FIG.
That is, when the lenses 138 and 13B focus on the blocks 30a and 30b of the block gauge 30, the focus becomes maximum.

Next, the moving distance (driving pulse count) Xl from the first origin position to the position where the count value of the first binarization pulse Bp1 is maximum and the second binarization pulse from the second origin position The value α (=X1 +X2+β) is the sum of the moving distance to the position where the count value is maximum and the thickness β of the block gauge.
Let α be a constant determined by the distance between the lenses of the first and second television cameras, and store the constant α. As shown in FIG. 11, this constant α is the focus position of the lens of the first television camera and the second television camera when they are respectively at the first origin position and the second origin position. Corresponds to the distance between them.

Next, when measuring the remaining thickness of the groove of the object to be measured, as shown in FIG. It is placed between the first and second television cameras so as to face both television cameras, and the light @La from the lenses of both television cameras passes through the bottom of the object to be measured 1. .

and first and second television cameras 12A and 1
2B are located at the first and second origin positions, respectively, and are moved from the origin positions toward the object to be measured 1. 1st
The focus positions of the lenses 13A and 13B when the second television camera is at the original position are respectively indicated by 01 and 02 in FIG. Each time each driving pulse is applied during the movement of the television cameras 12A and 12B, the first and second binarized pulses Bp1 and Bo3 are counted and the counted value is stored together with the counted value of the driving pulse. The generation of drive pulses is stopped when the focus positions of the lenses 13^ and 13B of both television cameras reach a position beyond the surface 1a of the object to be measured 1 and the bottom surface 103a of the groove by a certain distance.

Next, by comparing the already stored count values, the movement path 11 The remaining thickness of the groove can be determined by subtracting the remaining thickness measurement variable X from the constant α that has already been obtained. Find the thickness Xt.

In the above embodiment, the binarized pulses are counted over one field, but if interlaced scanning is performed, they may be counted over one frame. It is also possible to count over several fields or frames.

In each of the above embodiments, the groove of the object to be measured is directed toward the second television camera, but the object to be measured may be placed so that its optical axis passes through the bottom of the groove. Which side of the object to be measured is directed toward which television camera is arbitrary.

That is, in the method of the present invention, there is no need to take care to direct a specific surface of the object to be measured toward a specific television camera. In addition, the optical axis of the lens only needs to pass through the bottom of the groove at the start of measurement, and the position of the object to be measured in the optical axis direction at the start of measurement is arbitrary.
There is no need to precisely position the object to be measured at a specific position at the start of measurement. Therefore, it is advantageous for automatic inspection on a factory line, where there is a possibility that the object to be measured may be transported upside down, or where it is difficult to precisely position the object to be measured.

Although not mentioned in the above explanation, in order to reduce measurement errors, it is preferable not to take in unnecessary information from the television camera.

Therefore, we set an area to be measured on the screen of the television camera (the minimum necessary area surrounding the groove part), and only the 2 fit pulses of the screen included in this area are targeted for measurement. is preferable. Various known methods can be used to set such a region. For example, based on the vertical synchronization signal and horizontal synchronization signal separated from the video signal, the logic state is "1" in a predetermined area.
'', and open the gate to output the 2v1 pulse only when the area setting signal is generated.

In the above-mentioned embodiments, the test object was closed to the object to be measured, but the present invention can be widely applied to measuring the residual thickness of ij4 of any article.

In the above example, a pulse motor was used to move the television camera and the object to be measured relative to each other, but a servo motor could also be used, in which case the relative movement would be detected electrically. Displacement detection means is provided to detect the amount of displacement.

[Effects of the Invention] As described above, according to the present invention, the remaining thickness of the cat to be measured can be measured without contact using a television camera equipped with a microscope lens. Even in such a case, the remaining thickness of the groove itself can be measured without providing a dummy groove, and the remaining thickness of the groove can be appropriately managed. In addition, since the remaining thickness can be measured electrically, accurate measurements can be made in one go without requiring any skill on the part of the measurer.
It has the advantage of being able to

[Brief explanation of drawings]

FIG. 1 is a configuration diagram schematically showing an example of the configuration of a device used in an embodiment of the invention of Application 1, and FIG. 2 shows a flit with a block gauge attached to carry out the configuration of the device in FIG. 1. Figure 3 is an explanatory diagram showing the distribution of binary pulse count values during calibration in the same example along with the movement of the block gauge, and Figure 4 is a diagram showing the binary pulse count during measurement in the same example. An explanatory diagram showing the distribution of count values along with the beginning of the counter-dye to be measured. Figure 5 is an explanatory diagram explaining the principle of measurement by counting 2(il'i) pulses. A line diagram showing an example of the distribution of count values, FIG. 7 and FIG. FIG. 10 is a schematic configuration diagram of the device used in the embodiment of the invention, FIG. 10 is a configuration diagram showing the device used in the same embodiment with a block gauge installed, and FIGS. 11 and 12 are respectively for the same embodiment. Figure 13 is a plan view showing the UE5M as an example of the object to be measured. Fig. 15 is an enlarged cross-sectional view of the main part of the can lid, and Fig. 15 is a cross-sectional view of the main part to explain the problem when trying to measure the remaining thickness of the fine groove by the stylus method.1... Can Attraction (object to be measured), 103...Groove, 12
A...First television camera, 12B...Second
television camera, 13A...lens of the first television camera, 13B...lens of the second television camera, α...constant determined by distance between lenses, β...thickness of block gauge , X...residual thickness measurement variable, Xt...residual thickness. (1 other person) "・C-C Figure 2 Figure 7 Figure 8 Figure 10 Figure 14 o, o2 Figure 13 Figure 15

Claims (2)

[Claims] (1) In a method for measuring the residual thickness of a groove provided in an object to be measured, first and second microscope lenses are equipped with microscope lenses adjusted to focus on the object at a position separated by a set distance. television cameras are placed facing each other with the optical axes of their respective lenses aligned, and the first and second video signals obtained from the first and second television cameras are differentiated to obtain a predetermined signal. means for obtaining first and second binarized pulses by comparison with a threshold level; a block gauge is disposed between the first and second television cameras; the first and second binarized pulses are counted in the process of the movement, and from the position where the count value of one binarized pulse is maximum to the other Find the moving distance to the position where the count value of the binarized pulse is maximum, and add the thickness of the block gauge to the distance, and the value is determined by the distance between the lenses of the first and second television cameras. the object to be measured is placed between the two television cameras so that the optical axes of the two television cameras pass through the bottom of the groove of the object to be measured, and the object to be measured is placed between the two television cameras. Move in the optical axis direction relative to the television camera and count the first and second binarized pulses in the process of movement, and the count value of one of the binarized pulses becomes maximum. A moving distance from the position to a position where the count value of the other binarized pulse is maximum is determined as a residual thickness measurement variable, and the residual thickness is determined by subtracting the residual thickness measurement variable from the constant. How to measure the remaining thickness of a groove. (2) In a method for measuring the residual thickness of a groove provided in an object to be measured, first and second microscope lenses are equipped with microscope lenses adjusted to focus on the object at a position separated by a set distance. television cameras are placed facing each other with the optical axes of their respective lenses aligned, and the first and second video signals obtained from the first and second television cameras are differentiated to obtain a predetermined signal. means for obtaining first and second binarized pulses by comparison with a threshold level; a block gauge is disposed between the two television cameras, and the block gauge is opposed to both the television cameras; , each of the first and second television cameras
and from the second origin position toward the block gauge in the respective optical axis directions, and in the process of said movement, the first and second
Count the binarized pulses of
The thickness of the block gauge is the sum of the moving distance to the position where the count value of the digitizing pulse is maximum and the moving distance from the second origin position to the position where the count value of the second binarizing pulse is the maximum. The value added is a constant determined by the distance between the lenses of the first and second television cameras, and the object to be measured is placed between the first and second television cameras and faces both television cameras. and the optical axes of both television cameras pass through the bottom of the groove of the object to be measured, and the first and second television cameras are moved from the first and second origin positions to the object to be measured, respectively. move it towards the object, and in the process of the movement, the first and second
The moving distance from the first origin position to the position where the count value of the first binarized pulse is maximum by counting the digitized pulses and the second
The sum of the moving distance from the origin position to the position where the count value of the second binarized pulse is maximum is obtained as a residual thickness measurement variable, and the residual thickness is calculated by subtracting the residual thickness measurement variable from the constant. A method for measuring the remaining thickness of a groove, which is characterized by determining the remaining thickness of a groove.