JPH0527059B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a surface defect measuring device, and particularly to a surface defect measuring device suitable for measuring surface defects of various objects to be measured.

[Background of the invention]

Conventionally, optical surface defect measuring devices have been used as devices for measuring surface defects of various objects to be measured. This kind of conventional equipment irradiates the surface of the object to be measured with light and receives the reflected light of the irradiated light on the surface of the object to be measured.Based on the amount of light received, defects are generated on the surface of the object to be measured. It was configured to measure whether or not the test was successful.

However, with conventional devices, even if there is dust or the like on the surface of the object to be measured, it is determined that there is a defect such as a scratch on the surface of the object to be measured. However, there was a risk that it would be discarded as a defective product. Therefore, when inspecting using conventional equipment, it is necessary to manually re-inspect defective products, or to install a cleaning machine in the previous process to clean the surface of the object to be measured. was being carried out. Therefore, when conventional devices are used to measure surface defects on objects to be measured, there are problems such as a decrease in yield, an increase in the number of re-inspection steps, or an increase in equipment investment. In addition, Japanese Patent Application Publication No. 57-13340 and Japanese Patent Application Publication No. 58-62543
It is possible to adopt the method described in the publication, but these methods require multiple light sources or multiple light receiving elements, and have the disadvantage of increasing the size of the device. be.

[Object of the Invention] An object of the present invention is to irradiate the object with light from a single light source and reliably measure the presence or absence of surface defects on the object based on the reflected light from the object. The purpose of the present invention is to provide a surface defect measuring device that is capable of measuring surface defects.

[Summary of the Invention] In order to achieve the above object, the present invention provides a scanner that sequentially emits beam light whose optical axis changes, and a first scanner that sequentially irradiates the beam light from the scanner toward the surface of an object to be measured. a second light projector that sequentially irradiates the beam light from the scanner toward the side of the object to be measured, and a second light projector that receives the reflected light from the surface of the object to be measured and adjusts the amount of light received. a first photoelectric conversion unit that outputs an electric signal of a corresponding level; and a first photoelectric conversion unit that receives at least the beam light that has passed through the surface side of the object to be measured out of the beam light irradiated to the side surface of the object to be measured, and the received beam light. The second photoelectric conversion unit outputs two systems of electrical signals with different levels depending on the position of A calculation unit that outputs a signal, and a plurality of reference levels are set, and each output signal of the calculation unit and the first photoelectric conversion unit is compared with the reference level, and measurements on the object to be measured are performed based on the results of these comparisons. a determination unit that determines the result and outputs the determination result, and the determination unit is configured to match the level of the output signal of the first photoelectric conversion unit with the output signal of the first photoelectric conversion unit to be measured. When the level of the output signal of the calculation unit is different from the first reference level when the object is a non-defective item, and the level of the output signal of the calculation unit is different from the second reference level when the object to be measured is a non-defective item, which is associated with the output signal of the calculation unit. , it is determined that an object has adhered to the surface of the object to be measured, and the level of the output signal of the first photoelectric conversion section is different from the first reference level, and the level of the output signal of the calculation section is equal to the second reference level. When they match, it is determined that a defect such as a scratch has occurred on the surface of the object to be measured, and the level of the output signal of the first photoelectric conversion section is set to the first level.
The object to be measured is determined to be a non-defective product when the level of the output signal of the arithmetic unit matches the second reference level.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

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

In FIG. 1, a motor 1 is supported by a jig 10.
The surface of an object to be measured (hereinafter referred to as a workpiece) 14, which can be moved according to the drive of the workpiece 2, is irradiated with a beam light from a first light projecting section, and the side surface of the workpiece 14 is irradiated with a second light beam. A beam of light from the light projector is irradiated. That is, the laser beam emitted from the laser oscillator 16 passes through the optical scanner 18 and the lens 20 to the surface of the workpiece 14, and passes through the optical scanner 18, the slit 22, the lens 24, and the reflecting mirror 26 to the side surface of the workpiece 14. is irradiated.

The optical scanner 18 is configured to be able to rotate within a range of angle θ ₁ in response to a drive signal S output from a measurement unit 28 . Therefore, when the optical scanner 18 rotates within the range of angle θ ₁ , the laser light irradiated onto the lens 24 is irradiated onto the reflecting mirror 26 as a beam light moving within the range of angle θ ₂ , and is irradiated onto the lens 20 . The angle of the laser beam is θ ₃
The surface of the workpiece 14 is irradiated via the lens 20 as a beam of light that changes within a range of .

The laser beam irradiated onto the surface of the workpiece 14 is reflected by the surface of the workpiece 14, and a portion of the reflected light is transmitted to the light receiving element 32 via the lens 30. A first photoelectric conversion unit composed of a lens 30, a light receiving element 32, and an amplifier 34 receives reflected light from the light irradiated onto the surface of the workpiece 14, and outputs an electrical signal V _S at a level corresponding to the amount of received light. is configured to do so. That is, when the light reflected from the surface of the workpiece 14 is transmitted to the light receiving element 32 via the lens 30,
The light receiving element 32 outputs an electrical signal having a level corresponding to the amount of light received, and this electrical signal is amplified to a predetermined amplification degree by the amplifier 34 and output.

In this way, the light receiving element 32 is configured to output an electrical signal of a level corresponding to the amount of light received, so that the level of the output signal V _S of the amplifier 34 is adjusted to the level of the workpiece 1 When there are no objects such as dust attached to the surface of the workpiece 14 or defects such as scratches on the surface of the workpiece 14, the level _V1 is high because there is little diffused reflection. If the surface of the workpiece 14 is damaged or has defects such as scratches, the voltage will increase because diffused reflection will increase and the amount of light received will decrease.
The level is lower than V ₁ . That is, the level of the output signal V _S of the amplifier 34 decreases when something is attached to the surface of the work 14 or when a defect such as a scratch occurs on the surface of the work 14 .

On the other hand, the laser beam irradiated onto the side surface of the workpiece 14 is transmitted to the light receiving element 38 via the lens 36. A second photoelectric conversion unit composed of a lens 36 and a light receiving element 38 receives at least the laser beam that has passed through the front surface side of the workpiece 14 among the laser beams irradiated on the side surface of the workpiece 14, and determines the position of the received laser beam. It is configured to output two systems of electrical signals with different levels depending on the level.

That is, in this embodiment, as shown in FIG. 3, when no dust or the like is attached to the surface of the workpiece 14, the laser beam 10
0,102 is received, but if dust 40 or the like adheres to the surface of the workpiece 14, the laser beam 102 will not be transmitted to the light receiving element 38, but the laser beam 104 will be transmitted to the light receiving element 38. . Therefore, in this embodiment, among the laser beams irradiated on the side surface of the workpiece 14, the laser beam that has passed through the front side of the workpiece 14 is received, and two systems of electrical signals with different levels are generated depending on the position of the received laser beam. is to be output. The light receiving element 38 has three types: P, I, and N.
It is a PIN type position detection element composed of layers, and the light receiving surface is composed of a P layer which is a resistive layer, and electrodes are provided at both ends of the light receiving surface. When light is incident on the light receiving surface, a carrier generated in proportion to the energy of the incident light becomes a current source, and a current is extracted from each electrode that is distributed in inverse proportion to the resistance between the incident point and each electrode. . Here, the resistance between both electrodes is R, and the resistance between the incident point and each electrode is R ₁ , R ₂
Then, the current from each electrode is expressed by the following equation i ₁ ,
i ₂ is output.

i ₁ = R ₂ / R ₁ + R ₂ i ...(1) i ₂ = R ₁ /R ₁ + R ₂ i ...(2) Here, i is the total current generated (i = i ₁ + i ₂ ) show.

From the above equations (1) and (2), the output voltages V _A and V _B of each electrode of the light receiving element 38 are expressed by the following equations.

V _A = i ₁ × R ₁ ...(3) V _B = i ₂ × R ₂ ... (4) Here, if the amount of laser light input to the light receiving element 38 is always constant, the output voltage of the light receiving element 38 The sum remains constant even if the light receiving position changes.

V _C = V _A + V _B ... constant At this time, the value of V _A or V _B corresponds to the light receiving position.

However, the amount of laser light incident on the light receiving element 38 is not always constant, and variations in the amount of laser light are canceled out. Therefore, the light receiving position can be determined using either of the following equations.

V _Q =V _A /V _A +V _B ...(5) V _Q =V _B /V _A +V _B ...(6) V _Q =V _A −V _B /V _A +V _B ...(7) Photodetector The electrical signals of each of the 38 systems are processed by the calculation unit 42.
amplifiers 44 and 46.

The calculation unit 42 includes amplifiers 44, 46 and a calculation unit 48.
It consists of The amplifiers 44 and 46 are configured to amplify the output signals V _A and V _B from the light receiving element 38 to predetermined levels V _A ′ and V _B ′, respectively, and supply them to the arithmetic unit 48 .

The arithmetic unit 48 receives each output signal of the amplifiers 44 and 46.
A signal V _ADD =V _A ′+V _B ′ is obtained by adding V A ′ and V _{B ′} , and this signal is compared with the reference voltage V ₃ . At this time, if the laser beam is blocked by the workpiece 14, the laser beam will not be incident on the light receiving element 38, so V _A ′ and V _B ′ are approximately 0V. On the other hand, when the laser beam passes over the top surface of the workpiece 14 and directly enters the light receiving element 38, V _A ′ and V _B ′ suddenly increase, and V _ADD
will be about 3 to 5V. At this time, since V _ADD >V ₃ , calculations are performed to determine the light receiving position using the following equation.

V _Q = {(V _A ′−V _B ′)/(V _V ′+V _B ′)} V _Q obtained by the above formula is sampled and held and output as V _Q =V _P. ing. When no dust 40 or the like is attached to the surface of the workpiece 14, the laser beams 100, 104, and 102 are sequentially incident on the light receiving element 38, so that V _P =V ₂ as shown in FIG. signal is output. On the other hand, when dust 40 or the like is attached to the surface of the workpiece 14, the laser beam 10 is transmitted to the light receiving element 38.
Only 0.0,104 is incident, and the level of V _B ' is slightly lower than the level of V _A ' at the same sampling point,
A signal with V _P > V ₂ will be output. These signals are then supplied to the measurement unit 28.

The measurement unit 28 is composed of a determining section and a driving section. This drive section is configured to output a drive signal S for driving the optical scanner 18 and a drive signal D _P for driving the motor driver 50.

A plurality of reference levels are set in the judgment section, and the judgment section uses these reference levels and the output signals V _S , V _P
The measurement results for the workpiece 14 are determined based on the results of these comparisons, and the determination results are output.

The first reference level set in the judgment section is
The second reference level corresponds to the output signal V _S and is set to the level when the workpiece 14 is a good product, that is, the level V ₁ shown in FIG _. The level when the workpiece 14 is a good product, that is, the level c in FIG.
It is set corresponding to level V ₂ shown in .

In the apparatus of this embodiment configured as described above, when the triangular wave drive signal S is applied from the measurement unit 28 to the optical scanner 18,
The optical scanner 18 rotates within the range of angle θ ₁ , and the laser beam from the laser oscillator 16 is transmitted to the lens 2.
The laser beam is irradiated onto the front side of the workpiece 14 through the laser beam 24 and the side surface of the workpiece 14 through the lens 24 and the reflecting mirror 26. At this time, a movement pulse signal D _P synchronized with the drive signal S is supplied to the motor driver 50, and the workpiece 14 is moved by the rotational drive of the motor 12. As the optical scanner 18 and the workpiece 14 move, the measurement unit 28 measures the surface of the workpiece 14 within the _{angle θ 3 for} each scan by the drive signal S. The output signal of the light receiving element 32 is taken in, and the output of the light receiving element 38 in the range of angle θ ₂ is taken in, and the output signals V _S and V _P are compared with the first and second reference levels at the timing of each scanner. , based on these comparison results, work 14
Determine the measurement results for and output the determination results.

That is, as shown in FIG. 5a, the output signal
When V _S is different from the first reference level and the output signal V _P is different from the second reference level, it is determined that something has adhered to the surface of the workpiece 14, and as shown in FIG. 5b, The level of the output signal V _S is different from the first reference level, and the level of the output signal V _P is different from the first reference level.
When the reference level V ₂ of
4, the output level of the output signal V _S matches the first reference level V ₁ as shown in Fig. 5 c, and the output signal When the level of V _P matches the second reference level V ₂ , it is determined that the work 14 is a good product. By supplying and displaying these determination results on an external display device or the like, it is possible to accurately determine the presence or absence of a surface defect on the workpiece 14 based on the content displayed on the display device.

In this way, in this embodiment, when measuring surface defects on the workpiece 14, scratches and
Is there any defect such as adhesion of objects or workpiece 1?
It is possible to determine whether or not each item No. 4 is a good product.

Therefore, a workpiece 14 with dust, chips, etc. attached to its surface will not be judged as a defective product due to scratches, etc., so there is no need to re-inspect a defective product, and a washing machine is installed in the previous process. No need to install. Therefore, according to this embodiment, it is possible to improve yield, reduce re-inspection man-hours, and reduce equipment investment.

Furthermore, according to the embodiment, the surface defects on the workpiece 14 can be reliably measured without visually inspecting the surface defects on the workpiece 14, so that the efficiency of the measurement work can be improved and the quality can be improved. You can improve your performance.

〔Effect of the invention〕

As explained above, according to the present invention, light from a single light source is irradiated onto the surface and side surfaces of an object to be measured,
The reflected light from each surface is received by multiple light-receiving elements, and the surface defects of the object to be measured are measured based on the results of this light reception, which makes it possible to reliably measure surface defects of the object and downsize the device. can contribute to

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a diagram showing the relationship between the angle of the laser beam and the voltage, FIG. 3 is a diagram for explaining the configuration of the second photoelectric conversion section shown in FIG. 1, and a to c in FIG.
A waveform diagram for explaining the operation of the arithmetic unit shown in the figure,
5A to 5C are diagrams showing the relationship between laser beam angle and voltage, respectively. 12...Motor, 14...Work, 16...Laser oscillator, 18...Optical scanner, 2
0, 24, 36... Lens, 28... Measurement unit, 32, 38... Light receiving element, 42... Arithmetic unit,
34, 44, 46...Amplifier, 48...Arithmetic unit.

Claims (1)

[Claims] 1. A scanner that sequentially emits a beam light whose optical axis changes, a first light projector that sequentially irradiates the beam light from the scanner toward the surface of the object to be measured, and a scanner that emits the beam light from the scanner toward the surface of the object to be measured. a second light projecting section that sequentially irradiates the light toward the side surface; a first photoelectric conversion section that outputs an electrical signal at a level corresponding to the amount of received light received by the reflected light irradiated on the surface of the object to be measured; , receives at least the beam light that has passed through the surface side of the object to be measured out of the beam light irradiated to the side surface of the object to be measured, and outputs two systems of electrical signals with different levels depending on the position of the received beam light. A second photoelectric conversion section, a calculation section that calculates the ratio of the level of the electrical signal of each system of the output of the second photoelectric conversion section and outputs a signal according to the calculated ratio, and a plurality of reference levels are set. A determination unit that compares each output signal of the calculation unit and the first photoelectric conversion unit with the reference level, determines a measurement result for the object to be measured based on the comparison results, and outputs the determination result. , the determination unit calculates that the level of the output signal of the first photoelectric conversion unit is different from a first reference level when the object to be measured is a non-defective item in correspondence with the output signal of the first photoelectric conversion unit. determining that an object has adhered to the surface of the object to be measured when the level of the output signal of the section is different from a second reference level, which is associated with the output signal of the calculation section and is used when the object to be measured is a non-defective item; When the level of the output signal of the first photoelectric conversion section is different from the first reference level and the level of the output signal of the calculation section matches the second reference level, a defect such as a scratch occurs on the surface of the object to be measured. When it is determined that the output signal level of the first photoelectric conversion section matches the first reference level and the level of the output signal of the calculation section matches the second reference level, the object to be measured is a good product. A surface defect measuring device characterized by determining that.