JPH0820227B2 - Width between work and step detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an optical system by a light-section method using a laser or a light emitting diode (LED) on the light emitting side and a two-dimensional optical position detector on the light receiving side. The present invention relates to a device for detecting a width between works in a sensor and a step.

[Conventional technology]

Conventionally, for example, JP-A-63-71674 and JP-A-63-71674
As disclosed in JP-A-84851 or JP-A-63-95306, an optical sensor using a two-dimensional optical position detector by an optical cutting method is generally known, and this optical sensor is also known. A device for detecting a width between work and a step difference using a sensor is also known.

By the way, in the conventional width-between-workpieces and step detecting device, the width between the workpieces is detected by the method of the flowchart shown in FIG. 7 together with the signal waveform of the beam.

That is, as for the width between the works, first, the light quantities at a large number of sampling points on the signal waveform are respectively checked, and the number of samplings in the gap portion (30) equal to or less than the threshold value (29) is counted (step (71)). Next, the width between the works is calculated by the product of the ratio of the count number to the total number of samples and the beam length (step (72)). At this time, the beam length is treated as a constant.

[Problems to be Solved by the Invention]

In the conventional width-between-workpieces and step detecting device as described above, the width between the workpieces is detected by setting the beam length as a constant, but in reality, the beam length is from the workpiece to the sensor head. Since the height changes when the height changes, there is a problem that the width measurement value changes depending on the height of the sensor head even if the width between the works is constant.

The present invention has been made to solve the above problems, and even if the height of the sensor head from the work changes, the width between the works and the width between the works can be accurately and stably detected. Another object is to obtain a step detecting device.

[Means for solving the problem]

The width between work and the step detecting device according to the present invention are
A device for detecting a width and a step between workpieces by a light cutting method using a laser or an LED on a light emitting side and a two-dimensional optical position detector on a light receiving side, and a beam image on the two-dimensional optical position detector is detected. And a sampling point information storage means for storing the information of each of the plurality of sampling points, and for counting and storing the number of sampling points between the works whose light amount is a predetermined value or less among the sampling points, and the sampling point information storage. Beam image length calculation means for calculating the image length of the beam on the two-dimensional optical position detector based on the stored contents of the means;
Beam length calculating means for storing a relational expression showing a relation for obtaining an actual beam length from a beam image length on the three-dimensional optical position detector, and sampling between the works with the actual beam length. By multiplying the ratio of the number of points to the total number of sampling points, the width calculation means for calculating the width between the works, and the regression line is obtained from the points with stable variations among all the sampling points. Find the X coordinate of both ends between the workpieces,
A step calculating means for calculating the step between the works by obtaining the Y coordinate of the regression line at the X coordinates of the both ends is provided.

[Action]

In the present invention, when detecting the width between workpieces,
The actual image length of the beam is obtained by substituting the image length of the beam on the two-dimensional optical position detector into the relational expression obtained in advance. Then, using this actual beam length, the width between the works is calculated. Therefore, even if the height from the work to the sensor head changes, the width and step between the works can always be detected accurately and stably.

〔Example〕

FIG. 1 is an overall configuration diagram showing an embodiment of a device for detecting a width between work pieces and a step difference according to the present invention. In this embodiment, as is clear from FIG. 1, sampling point information storage means (1) for storing information on a plurality of sampling points on the beam image on the two-dimensional optical position detector, and A relational expression storage means (2) for storing a relational expression showing the relation between the length of the beam image on the two-dimensional optical position detector and the actual length of the beam is provided, and the beam image length calculation means (3) is provided.
In the above, the length of the image of the beam on the two-dimensional optical position detector is calculated based on the stored contents of the sampling point information storage means (1), and the beam image length calculation means (3) and the relational expression storage means are calculated. Based on each output from (2), the actual beam length is calculated in the beam length calculation means (4), and the width calculation means is calculated based on this beam length and the stored contents of the sampling point information storage means (1). In (5), the width between the works is calculated. Further, the step difference between the works is configured to be calculated by the step calculation means (6) based on the stored contents of the sampling point information storage means (1).

FIG. 2 is a perspective view showing the structure of the optical sensor used in the embodiment of FIG. 1, and FIG. 3 is a block diagram showing the hardware structure thereof. In the figure, (7) is a light source by laser or LED, and the light from this light source (7) passes through a condenser lens (8), a mirror (9), a scanning mirror (10), and a mirror (11). After being incident on the welding line (13) of the object (12) and receiving a part of the reflected light (14) from this incident portion by the light receiving lens (16) provided in the lens holder (15), 2 The light is focused on the dimensional light position detector (17). (18) is a sensor head that houses the above-mentioned components. (19) is a preamplifier that amplifies the signal from the two-dimensional optical position detector (17), (20) is a bandpass filter (BPF) composed of operational amplifiers, etc. (21) is the output signal of the BPF (20). A half-wave rectifier circuit for rectifying, (22) a low-pass filter (LP) based on an analog signal of the current signal, which is an output signal of the half-wave rectifier circuit (21), and (23) a subtractor composed of an operational amplifier or the like, ( 24) is an adder of similar configuration, (25)
Is a divider that receives the output from the subtracter (23) and the adder (24) to perform division, and (26) samples the analog signal of the operation result of the divider (25) and only the time required for signal conversion Sample hold circuit (S / H) for holding, (27)
Is an analog switch (ASW) composed of field effect transistors and the like, and (28) is an A / D converter which outputs the converted digital signal to the CPU bus.

 Next, the operation of the above embodiment will be described.

First, the width detection between works will be described with reference to the width detection flowchart shown in FIG. In step (41) shown in FIG. 4, step (71) in FIG.
Similarly to, the number of sampling points of the light amount equal to or less than the threshold value (29) corresponding to the gap portion (30) is counted. Next, in step (42), the length of the image of the beam on the two-dimensional optical position detector (17) is obtained. Specifically, as shown in FIG. 5, the X-coordinates (X _LO ) and (X _RO ) at both ends of the beam image (51) on the two-dimensional optical position detector (17) are calculated to obtain the beam image. Find the length of (| L _LO −X _RO |).

Then, in step (43), the beam image (51)
Of the beam image (5) obtained in step (42) in advance.
The actual beam length is calculated by substituting the length of 1) into the above relational expression.

Then, in step (44), the ratio of the number of sampling points of the gap portion (30) obtained in step (41) to the total number of sampling points is multiplied by the actual beam length obtained in step (43). , Find the width between workpieces.

Next, step detection between workpieces will be described with reference to the flowchart of step detection shown in FIG. 6A and the signal waveform diagram corresponding to this flowchart shown in FIG. 6B. First, in step (61), the left regression line (32) of the portion (31) where the sampling point is reliable (a stable area with few variations) is obtained.

Next, in step (62), the X coordinate (X _L ) of both ends of the light amount DARK, that is, the gap (30),
Find (X _R ).

Then, in step (63), the right regression line (34) of the portion (33) where the sampling point is reliable is obtained.

Next, in step (64), the Y coordinate (Y _L ) of the left regression line (32) whose X coordinate is (X _L ) and the Y coordinate (Y Y) of the right regression line (34) whose X coordinate is (X _R ). _R ) are calculated respectively. Thereafter, in step (65), we obtain the level difference between the work (Y _R -Y _L).

In addition, although the threshold value (29) for determining the gap portion (30) is a constant in the above embodiment, it may be a variable obtained from the ratio of the maximum light amount and the minimum light amount.

〔The invention's effect〕

As described above, the present invention uses the relational expression showing the relationship between the length of the image of the beam and the actual length of the beam to detect the width of the workpiece and the step difference between the workpiece and the actual length of the beam. Calculate the width between the workpieces by multiplying the actual beam length by the ratio of the sampling points between the workpieces to the total sampling points,
In addition, a regression line is obtained from stable points with little variation among all sampling points, X-coordinates of both ends between works are obtained from sampling points between works, and X of both ends is calculated.
Since the step between the works is calculated by obtaining the Y coordinate of the regression line in the coordinates, there is an effect that a width between the works and a step detecting device with relatively high accuracy can be obtained. .

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a work width and step detecting device according to an embodiment of the present invention, FIG. 2 is a perspective view of an optical sensor, and FIG. 3 is a block diagram showing its hardware configuration. FIG. 4 is a flow chart showing the width detecting method in the above embodiment, FIG. 5 is an explanatory view showing a method for obtaining the length of the image of the beam on the two-dimensional optical position detector, and FIG. 6 (A) is the above embodiment. A flow chart showing a step detection method in
FIG. 6 (B) is a signal waveform diagram corresponding to the flow chart shown in FIG. 6 (A), FIG. 7 (A) is a flow chart showing a width detecting method in the conventional apparatus, and FIG. 7 (B) is FIG. It is a signal waveform diagram corresponding to the flowchart of (A) description. (1) …… Sampling point information storage means (2) …… Relational expression storage means (3) …… Beam image length calculation means (4) …… Beam length calculation means (5) …… Width detection means (6)… ... step detecting means (7) ... light source (17) ... two-dimensional optical position detector (18) ... sensor head In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A device for detecting a width and a step between workpieces by a light cutting method using a laser or an LED on a light emitting side and a two-dimensional optical position detector on a light receiving side. Sampling point information storage means for storing information on each of a plurality of sampling points on the image of the beam, and for counting and storing the number of sampling points between works whose light quantity is a predetermined value or less from among the sampling points, Based on the stored contents of the sampling point information storage means,
Beam image length calculation means for calculating the length of the beam image on the two-dimensional optical position detector, and for obtaining the actual beam length from the length of the beam image on the two-dimensional optical position detector And a beam length calculating means for storing a relational expression indicating the relationship between the actual beam length and a width calculating means for calculating the width between the works by multiplying the actual beam length by the ratio of the number of sampling points between the works to the total number of sampling points. And a regression line is obtained from stable points with little variation among all sampling points, X-coordinates of both ends between works are obtained from sampling points between the works, and Y-coordinates of the regression line at the X-coordinates of the ends are obtained. By
A step difference calculating unit for calculating a step difference between works, and a device for detecting a width between steps and a step difference.