JPS62137503A - Method and device for optically inspecting precision of sizeof part or test piece - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for optical inspection, verification or testing of precision down to the thickness of parts or specimens. The part or specimen to be measured is passed through parallel radiation from a photoelectric transmitter and detected by a photoelectric receiver,
The strength of the electrical signal converted therefrom is proportional to the respective range of the radiation cross section measured by the receiving device.

DESCRIPTION OF THE PRIOR ART DE 2818060 discloses a device for optical dimensional inspection of test specimens, in which the contour of the test specimen is determined by the emission of parallel light beams from a light source.
It is projected onto a remote receiving device. The signal strength of the photocell is proportional to the surface area illuminated by the light source and is fed to two analog computers that perform addition and subtraction. When there is a difference from zero, the switching element or gate is controlled to pass or gate the sum of the photocell currents, which sum is compared with a reference value in a comparator. This known device is relatively complex. This is because in each case a summation or a difference must be formed. The amount of computation required also limits the speed with which specimens can be inspected. In this known device, the thickness of the specimen to be examined is also limited. This is because the beam path from a point source cannot be expanded randomly.

Problems to be Solved by the Invention An object of the present invention is to provide an optical inspection method and apparatus that enables rapid and accurate measurement with accuracy up to the size of a component or test piece, while also making it possible to measure larger parts or test pieces. The goal is to provide the following.

Means for solving the problem According to the invention, the above-mentioned problem is solved by a characteristic feature of the main claim, which is combined with the components mentioned in the preamble. By providing two transmitting devices and varying the spacing of the two transmitting devices or one receiving device in each case associated with one receiving device,
It can be easily adapted to the size of the part or specimen to be measured. The part or specimen can be measured in rapid succession. This is because in the special case where the total radiation cross section measured by the first receiving device is shielded by a component or test piece, the component or test piece of the total radiation cross section measured by the second receiving device The area covered by the piece is measured.

As a result, no further mathematical operations are necessary.

Its absolute value is compared to a reference value previously established by a series of measurements on a reference part or specimen. Since very fast measurements are possible, stamping (stamping)
pings) and stamping machines
The method and apparatus can be used in the optical inspection of similar bulk product sizes provided by rapid processing such as by g machine).

The measures of the dependent claims allow further advantageous developments and improvements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the invention, together with the method according to the invention, will be described in more detail below with reference to the accompanying drawings, in which: FIG.

Accurate optical inspection equipment for dimensions of more than one dimension, such as stampings, is in each case located on the optical axis! It is based on the principle of partially covering two parallel beam bundles received by one of the radiation receiving devices facing the radiation source.

The part or specimen moves at right angles to the two beam bundles. FIG. 1 shows the basic structure of a measuring device, which has two radiation sources 1 and 2, e.g. Facing the phototransistor. The radiation from transmitting devices 1 and 2 is in each case focused by lenses 5 and 6, so that 1
This results in two parallel ray bundles. This bundle of rays is incident on the lenses 7 and 8, which project this radiation onto the receiving devices 3 and 4. The part or specimen 9 is passed through an optical path from bottom to top in this figure, so that part of the radiation is blocked and the receiving devices 3 and 4 only measure the remaining radiation. The electrical signals supplied by the receiving devices 3 and 4 end up measuring the individual shielding by the component or specimen.

As can be seen in FIG. 2, the receiving devices 3 and 4 are constructed as phototransistors, the collector-emitter junction of which has a lower impedance when radiation strikes the base. There is a non-linear relationship between the instantaneous radiation intensity and the collector current of the phototransistor, so that a certain linearity is obtained by sizing the resistance and a diaphragm (not shown).

The transmitting devices 1 and 2 are supplied by constant current sources controlled by a microprocessor 14 via digital-to-analog converters 12 and 13.

The radiation intensity of the transmitting devices 1 and 2 can therefore be controlled within wide limits. Therefore, the radiation intensities of the transmitting devices 1 and 2 can be independently set at a specific distance between the transmitting device and the receiving device. The radiation-generated signals from the receiving devices 3 and 4 connected as a voltage divider are amplified by amplifiers 15 and 16 and are routed via a switching device 17 to an analog amplifier circuit 18.
and via an analog-to-digital converter 19 to a microprocessor 14 for further processing and measurement. The switching device 17 is the receiving device 1 or 2.
signals to amplifiers and analog-to-digital converters. The analog amplifier circuit 18 has the following two
It is controlled by the microprocessor via a switch 20 which performs two functions.

b.) During setup, the signal of the receiving device 3 or 4 is directly fed to the analog-to-digital converter 19 for determining the radiated power.

] connected to the corresponding reverse voltage, so that the signal supplied to the analog-to-digital converter is O volts (T) when received unshielded. This allows the test signal to be standardized from 0 to 10V, where QV indicates total radiation and IOV indicates total shielding. Transmitter R1
Regardless of the voltage level appearing at the collectors of the receivers 3 and 4 at a particular intensity of radiation from the receivers 3 and 2, the microprocessor can utilize a well-defined gain to control the amplifier circuit 18.

The signal of the amplifier 16 is also supplied to a threshold switch 21 which acts as a trigger stage. At the same time, the digital-to-analog converter 22 applies the value of 50 degrees of shielding determined by the settings as the trigger threshold. This value is necessary to start the measurement process. The external trigger is used to initiate the measurement process by an external signal generator or, as one of the measurement functions, to initiate the process of automatically adapting the radiant intensity as a function of the surrounding brightness. Ru.

Connected to the microprocessor 14 is a display 24 which may be of the alphanumeric type or may have a bar display with bright dots. There are also control elements, such as a keyboard 25, for example.

A series of measurements begins by fixing a reference value to which subsequently measured values of different parts or specimens are to be compared. For this purpose, using the display device 24, the operator causes a reference part or specimen to pass through the radiation.

The threshold voltage of the threshold switch 21 is such that the threshold switch 21 provides a trigger pulse to the microprocessor when 50% of the total radiation cross section measured by the receiver 4 is blocked. Configured by digital-to-analog converter 22.

The output signal of the amplifier 15 is connected to the switching device 17 and the analog-
is present in the microprocessor 14 via a digital converter 19 and is measured for radiation shielded by the receiving device 3 or component or test piece 9 to which the radiation reaches, but is not shown separately. stored in memory.

This memory indicates that the part or specimen 9 is at the center of the radial cross section.
This is done when the signal of the amplifier 15 is in the voltage range of, for example, 3.3 to 6.6 pol (V). This is because when setting, the receiving device signal is set to 0.
This is because standardization is being carried out to 10V to 10V. if,
Via the alphanumeric display 24, the microprocessor 14 indicates that the sensor 1 must be moved when the occlusion is outside the middle % of the radiation cross section measured by the receiver 3. . At this time, the measurement process regarding the reference value is repeated until the entire radiation cross section measured by the receiving device 3 falls within the allowable range. After this process, the reference value is stored in the microprocessor 14.

During the actual measurement process, the component or specimen 9 passes rapidly through two radiation paths in succession. Then, when 50 inches of the radiation cross section measured by the receiving device 4 is covered, the threshold pulse switch 21 supplies a trigger pulse to the microprocessor 14. This microprocessor compares the signal corresponding to the output signal of the receiving device 3 at the output of the analog-to-digital converter 19 with a stored reference value and checks that the signal is within predetermined tolerance limits. Determine whether it exists or not. To this end, after each measurement, a status signal or flag is enabled to control relay contacts or other electrical outputs so that defective products can be isolated.

[Brief explanation of drawings]

1 is a drawing showing a transmitting device and an emitting device together with the associated beam flux passing through a component or specimen, and FIG. 2 is a circuit diagram of a device according to the invention. In the drawings, 1; 2: Photoelectric transmitter 3; 4: Receiver 5; 6; 7
;8: Lens 9: Parts (test piece) 10; 11: Constant current source

Claims (1)

Claims: 1) A method for optically inspecting the size accuracy of a part or test piece, wherein the part or test piece to be measured is passed through parallel radiation of a photoelectric transmitter and then subjected to a photoelectric receiver. detected by a device and converted into a signal proportional to the respective occlusion of the cross-section of the radiation measured by the receiving device;
Said method, wherein in each case two transmitting devices are associated with one receiving device, said transmitting devices or receiving devices mutually at a maximum distance corresponding to the external dimension of said component or specimen. and when a certain portion of the total radiation cross section measured by the first receiving device is shielded by the part or test piece, the radiation cross section measured by the second receiving device is The portion of the total radiation cross-section covered by the component or specimen is measured and compared to a reference value, which reference value is determined prior to the series of measurements.
Said method, characterized in that measurements are taken with a reference part or specimen at said certain shielded part and stored. 2) The spacing between the transmitting devices is such that the shielded portion corresponding to the reference value of the radiation transmitted by the second transmitting device and measured by the second receiving device has a predetermined radiation cross-sectional area. A method according to claim 1, wherein the method is fixed within a limited range. 3) A method according to claim 2, wherein the shielding portion is projected onto the central third of the radiation cross section. 4) two photoelectric transmitting devices are provided with a maximum distance from each other corresponding to the external dimensions of the component or specimen to be inspected, each associated with one receiving device; If a certain part of the total radiation cross section measured by the first receiving device is occluded, the part of the reference or test is stored in memory and prior to a series of measurements when said certain part is occluded. Device for carrying out an optical inspection method for the accuracy of the size of a component or test piece, characterized in that it is compared with a reference value determined by the piece. 5) The device according to claim 4, wherein the intensity of the radiation from the transmitting device can be controlled solely by a constant current source. 6) When the certain part is covered, the second
A device according to claim 4 or 5, characterized in that it is provided with a control device for supplying a trigger pulse for measuring the shielded part of the total radiation cross section measured by the receiving device. . 7) The device according to claim 4, 5 or 6, wherein the receiving device is configured as a phototransistor.