JPH071233B2 - Surface defect measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface defect measuring device, and more particularly to a surface defect measuring device suitable for measuring surface defects of various measured objects.

BACKGROUND OF THE INVENTION As a device for measuring surface defects of various measured objects, conventionally,
An optical surface defect measuring device was used. This type of conventional device receives light on the surface of the object to be measured and receives the reflected light of the light irradiated on the surface of the object to be measured, and based on the amount of received light,
It is configured to measure whether or not a defect has occurred on the surface of the measured object.

However, in the conventional device, even if dust or the like is attached to the surface of the object to be measured, it is determined that a defect such as a scratch has occurred on the surface of the object to be measured, and it is a non-defective product without scratches or the like. However, it could be discarded as a defective product. Therefore,
When inspecting using a conventional device, a defective product is manually re-inspected, or a washing machine is installed in the previous process to clean the surface of the measured object. . Therefore, when the conventional apparatus is used, when measuring the surface defect of the measured object, there is a problem that the yield is reduced, the number of re-inspection steps is increased, or the capital investment amount is increased.

[Object of the Invention]

The present invention has been made in view of the above conventional problems, and an object thereof is to provide a surface defect measuring device capable of reliably measuring the presence or absence of a surface defect of an object to be measured.

[Outline of Invention]

In order to achieve the above object, the present invention has a light projecting unit that irradiates light while scanning the surface of the measured object, and a light-receiving surface that receives reflected light of the light irradiated on the surface of the measured object. The light receiving surface is composed of a resistance layer, both ends of the light receiving surface are connected to electrodes, and a pair of electric signals obtained by dividing the voltage generated between the electrodes according to the light receiving position of the light incident on the light receiving surface is divided into two. A photoelectric conversion unit that outputs and a calculation unit that calculates a first electric signal corresponding to the received light intensity from the sum of the electric signals output from the photoelectric conversion unit and a second electric signal corresponding to the light receiving position from the ratio of the electric signals. And the first and second reference levels associated with the levels of the first and second electric signals are set as the levels when the measured object is a non-defective item. These reference levels and the first and second reference levels are set. The electrical signal level of the A determination unit that determines a result and outputs a determination result, wherein the determination unit applies to the object to be measured when the levels of the first and second electric signals are different from the first and second reference levels, respectively. When it is determined that an object has adhered and the level of the first electric signal is different from the first reference level and the level of the second electric signal matches the second reference level,
It is determined that a defect such as a scratch has occurred on the surface of the measured object, and when the levels of the first and second electric signals match the first and second reference levels, respectively, the measured object is a good product. It is characterized by determining that.

Example of Invention

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a preferred embodiment of the present invention.

In FIG. 1, a jig 14 is connected to a slide member 12 that slides according to the drive of a drive motor 10, and an object to be measured (hereinafter referred to as a work) 16 is attached to the jig 14. . Therefore, the work 16 can be moved according to the movement of the slide member 12. Further, on the surface of the work 16, a laser projector 18, an optical scanner 20, a lens 22
The light beam is emitted from the light projecting section.

The optical scanner 20 is configured to be rotatable within the range of the angle θ1 by the drive signal S output from the measuring unit 24. Therefore, when the optical scanner 20 rotates in the range of the angle θ1, the laser light emitted from the optical scanner 20 to the lens 22 is applied to the surface of the work 16 as a beam light moving in the range of the angle θ1.

The laser light applied to the surface of the work 16 is reflected by the surface of the work 16, and a part of the reflected light is transmitted to the light receiving element (PsD) 28 via the lens 26. The photoelectric conversion unit including the lens 26 and the light receiving element 28 receives the reflected light of the light irradiated on the surface of the work 16 and outputs two systems of electric signals a and b having different levels according to the light receiving position and the light receiving intensity. Is configured to. That is, the light receiving element 28 is a PIN type position detecting element composed of three layers of P, I and N, the light receiving surface of which is a P layer which is a resistance layer, and electrodes are provided at both ends of the light receiving surface. There is. Then, when light is incident on the light receiving surface, carriers generated in proportion to the energy of the incident light become a current source,
A current, which is distributed in inverse proportion to the resistance between the incident point and each electrode, is taken out from each electrode. Here, if the resistance between both electrodes is R and the resistance between the incident point and each electrode is R ₁ and R ₂ ,
The currents i ₁ and i ₂ shown in the following equation are output from each electrode.

Here, i represents the total generated current (i = i ₁ + i ₂ ).

From the equations (1) and (2), the output voltages Va and Vb of the electrodes of the light receiving element 28 are represented by the following equations.

Va = i ₁ × R ₁ (3) Vb = i ₂ × R ₂ (4) Here, when the amount of laser light input to the light receiving element 28 is always constant, the sum of the output voltages of the light receiving element 28 is It remains constant even if the position changes.

Vc = Va + Vb ... Constant At this time, the value of Va or Vb corresponds to the light receiving position.

However, the amount of laser light incident on the light receiving element 28 is not always constant, and the variation of the amount of laser light is canceled. Therefore, the light receiving position can be obtained by any of the following equations.

The electric signals a and b are output as signals whose level ratios are always kept constant even if the received light intensity changes.
Then, these electric signals a and b are supplied to the arithmetic unit 30.

As shown in FIG. 2, the arithmetic unit 30 is composed of amplifiers 32 and 34, an addition circuit 36, and a division circuit 38. Electrical signal a,
b is amplified with a predetermined amplification degree by the amplifiers 32 and 34, respectively, and output as electric signals a1 and b1. The electric signals a1 and b1 are added to the adder circuit 36, and the electric signal V _A (V _A = a1 + b1) is output from the adder circuit 36. That is, the adder circuit 36 outputs the electric signal V _A according to the received light intensity.

On the other hand, the output signal V _A of the adder circuit 36 and the electric signal b1 are added to the division circuit 38, and the electric signal V _D = b1 from the division circuit 28 according to the ratio between the electric signal a1 and the electric signal b1. / (A1 + b1) is output. Each electrical signal V _A , V _D is measured unit 24 respectively
Is supplied to.

The measurement unit 24 includes a determination unit and a drive unit. Of these, the drive section outputs a drive signal S for driving the optical scanner 20 and a motor driver.
It is configured to output a drive signal Dp that drives 40.

On the other hand, a plurality of reference levels are set in the determination unit,
The determination unit is configured to compare the reference level with the output signals V _A and V _D , determine the measurement result for the work 16 based on the comparison result, and output the determination result.

As shown in (c) of FIG. 3, the first reference level set in the determination unit is the reference level V1 associated with the electric signal V _A as the level when the work 16 is non-defective.
The second reference level is the work
The second reference level V2 associated with the electric signal V _D is set as the level when 16 is a non-defective item.

In the apparatus of the present embodiment configured as described above, when the measurement unit 24 supplies the drive signal S having a triangular wave shape to the optical scanner 20, the optical scanner 20
Rotates in the range of an angle θ1, and the laser light emitted from the laser projector 18 is irradiated onto the surface of the work 16 as laser beam light via the optical scanner 20 and the lens 22.
At this time, the movement pulse signal Dp synchronized with the driving signal S is supplied to the motor driver 40, and the work 16 is moved by the rotational driving of the driving motor 10. With the rotation of the optical scanner 20 and the movement of the work 16, the measurement unit 24
In order to measure the surface of the workpiece 16 within the range of the angle θ1 by the drive signal S for each scan, the electric signals V _A and V _D based on the output signals a and b of the light receiving element 28 within the angle θ1 are taken in. , The electric signals V _A and V _D are compared with the first and second reference levels, the measurement result for the work 16 is determined based on the comparison result, and the determination result is output.

That is, as shown in the FIG. 3 (a), the signal V _A first
When the reference level V1 of is different and the output signal V _D and the second reference level V2 are different, it is determined that the surface of the work 16 is attached with dust, swarf, etc. As shown, when the level of the output signal V _A is different from the first reference level V1 and the level of the output signal V _D matches the second reference level V2, scratches, cavities, etc. on the surface of the work 16 occur. It is determined that a defect has occurred, and as shown in (c) of FIG. 3, the level of the output signal V _A matches the first reference level V 1, and the level of the output signal V _D is the second level. When it matches the reference level V2 of, it is determined that the work 16 is a good product. Then, these determination results are supplied to an external display device,
The contents are displayed. Therefore, it is possible to accurately determine the presence or absence of the surface defect of the work 16 based on the content displayed on the display device.

As described above, in the present embodiment, when measuring the surface defect of the work 16, it is determined whether the surface of the work 16 has a defect such as a scratch or an adhesion of a substance, and whether or not the work 16 is a good product. can do. Therefore, it is not necessary to re-inspect the defective product because it is not possible to determine that the dust and chips attached to the surface of the work 16 are defective products due to scratches, etc. No need to install. Therefore, according to this embodiment, it is possible to improve the yield, reduce the number of re-inspection steps, and reduce the amount of capital investment.

Further, according to the above-mentioned embodiment, even if the surface defect of the work 16 is not visually inspected, the surface defect of the work 16 can be surely measured, so that the efficiency of the measurement work can be improved and the quality can be improved. Can be achieved.

〔The invention's effect〕

As described above, according to the present invention, the surface of the object to be measured is irradiated with light, and the light reflected from the surface of the object to be measured is received by the light receiving element. According to the two levels of different electrical signals, it is determined whether the measured object is a good one, whether the object has adhered to the surface of the measured object, or whether the measured object has a defect such as a scratch. Therefore, it is possible to reliably measure the surface defect of the object to be measured, improve the work efficiency of the surface defect measurement, and improve the quality of the object to be measured. Since a washing machine is not required, there is an excellent effect that the equipment cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
A specific configuration diagram of the calculation unit shown in the figure, (a) to FIG.
(C) is a diagram showing a relationship between a laser beam angle and a voltage. 10 ... Drive motor, 14 ... Jig, 16 ... Object to be measured, 18 ...
… Laser projector, 20… Optical scanner, 22, 26…
… Lens, 24… Measuring unit, 28… Light receiving element, 30…
… Calculator, 36 …… Adding circuit, 38 …… Division circuit, 40 …… Motor driver.

Claims (1)

[Claims] 1. A light projecting unit for irradiating light while scanning the surface of an object to be measured, and a light receiving surface for receiving reflected light of the light irradiated on the surface of the object to be measured, the light receiving surface being a resistance. A photoelectric conversion unit that is composed of layers and has both ends of the light receiving surface connected to electrodes, and that outputs a pair of electric signals obtained by dividing the voltage generated between the electrodes into two according to the light receiving position of the light incident on the light receiving surface; The calculation unit that calculates the first electric signal corresponding to the received light intensity from the sum of the electric signals output from the photoelectric conversion unit and the second electric signal corresponding to the light receiving position from the ratio of the electric signals, and the measured object are non-defective , The first and second reference levels associated with the levels of the first and second electric signals are set, and these reference levels and the levels of the first and second electric signals are set. Compare the results, judge the measurement results for the object under measurement based on these comparison results, and And a determination unit that applies force, the determination unit determines that an object has adhered to the measured object when the levels of the first and second electric signals are different from the first and second reference levels, respectively. , When the level of the first electric signal is different from the first reference level and the level of the second electric signal matches the second reference level, it is determined that a defect such as a scratch has occurred on the surface of the measured object. A surface defect measuring device, characterized in that the object to be measured is judged to be non-defective when the levels of the first and second electric signals coincide with the first and second reference levels, respectively.