JPH0314123B2 - - 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, an optical surface defect measuring device has been used as a device for measuring surface defects of various objects to be measured. This device 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 this amount of received light, it is configured to measure whether or not a defect has occurred on the surface of the object to be measured.

However, with conventional devices, even if there is dust or the like attached to 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 re-inspect defective items manually or install a cleaning machine in the previous process to clean the surface of the object to be measured. It was being done. 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.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a surface defect measuring device that can reliably measure the presence or absence of surface defects on an object to be measured.

[Summary of the invention]

In order to achieve the above object, the present invention includes a light projection unit that irradiates light onto the surface of the object to be measured, and a light projector that collects the reflected light of the light irradiated onto the surface of the object to be measured and transmits this light into two systems. a transmission section that divides into transmission paths and transmits; a first photoelectric conversion section that receives light transmitted through the one transmission path and outputs an electrical signal at a level corresponding to the amount of received light;
It has a light-receiving surface that can receive the light transmitted through the reference transmission path and the light transmitted through the transmission path deviated from the reference transmission path among the light transmitted through the other transmission path, and the light incident on the light-receiving surface is Levels vary depending on location 2
a second photoelectric conversion unit that outputs a system electrical signal;
a calculation unit that receives electrical signals from each system of the second photoelectric conversion unit, calculates a ratio of the levels of the electrical signals of the two systems, and outputs a signal of the calculated ratio; The output level of the first photoelectric conversion section is compared with a first reference level determined as the output level of the calculation unit when an object adheres to the surface of the object to be measured. Alternatively, compare the output level of the first photoelectric conversion unit with a second reference level determined as the output level of the first photoelectric conversion unit when a defect occurs on the surface of the object to be measured, and calculate the measurement results for the object based on these comparison results. a determination unit that makes a determination and generates a determination output, and the determination unit is configured such that the output level of the calculation unit is equal to or lower than a first reference level
It is determined that a defect has occurred on the surface of the object to be measured when the output level of the photoelectric conversion section is below the second reference level, and when the output level of the calculation section exceeds the first reference level and the first photoelectric conversion section is The output level of the converter is the second
When the output level of the calculation section is below the first reference level, it is determined that something has adhered to the surface of the object to be measured, and the output level of the first photoelectric conversion section is below the first reference level. The device is characterized in that when it exceeds a reference level, it is determined that the object to be measured is a non-defective product, and an output is generated in accordance with each determination result.

[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.

As shown in FIG. 1, the apparatus in this embodiment includes a light projecting section 10, a transmission section 12, a first photoelectric conversion section 14, a second photoelectric conversion section 16, a calculation section 18, a determination section 20, etc. The light emitting unit 10 and the transmitting unit 12 are connected to an object to be measured (hereinafter referred to as a work) 2.
It is installed above the surface of 2.

The light projecting unit 10 includes a laser oscillator 24 and a light projecting lens 2.
6, the surface of the workpiece 22 moving in the direction of the arrow X is irradiated with laser light from a laser oscillator 24 via a projection lens 26. The light irradiated onto the surface of work 22
2, and the reflected light is reflected on the transmission section 12.

The transmission unit 12 is composed of a light receiving lens 28 and a beam splitter 30. The light reflected from the workpiece 22 is collected by the light receiving lens 28, and the collected light is transmitted through two systems by the beam splitter 30. Road 1
It is configured to be divided into 00 and 102 parts and transmitted.

In the middle of the transmission line 100, a light receiving element, such as a photodiode, a photomal, etc., constituting the first photoelectric section 14 is installed, and the light transmitted through the transmission line 100 is received by the light receiving element 14, and this An electrical signal of a level corresponding to the amount of light received is sent to the light receiving element 14.
It is output from. The output signal of the light-receiving element 14 is amplified to a predetermined level Vp by an amplifier 32 and supplied to the determination section 20.

Furthermore, since the light receiving element 14 is configured to output an electrical signal at a level corresponding to the amount of received light,
The output voltage Vp of the amplifier 32 has a high voltage value when there is no dust or other defects on the surface of the work 22 or defects such as scratches on the surface of the work 22 because there is little diffused reflection. When something is attached to the surface of the workpiece 22 or a defect such as a scratch occurs on the surface of the workpiece 22, diffused reflection increases and the amount of received light decreases, resulting in a low voltage value. Therefore, the output voltage Vp of the amplifier 32 may change if something is attached to the surface of the workpiece 22 or if the workpiece 22 is
If there are defects such as scratches on the surface of the
As shown in the figure, as the workpiece 22 moves, the voltage level of the portion corresponding to the light irradiated onto scratches, dirt, etc. on the workpiece 22 decreases.

On the other hand, in the middle of the transmission path 102, a light receiving element that constitutes the second photoelectric conversion section 16, such as a semiconductor position detection element, an image sensor, etc., is installed.
This light receiving element 16, as shown in FIG.
The light transmitted through the reference transmission path 102A when no dust or the like is attached to the surface of the workpiece 22 and the workpiece 22
has a light-receiving surface capable of receiving light transmitted from the light-receiving lens 28 via the beam splitter 30 through the transmission line 102B which is deviated from the reference transmission line 102A, and which has dust 34 etc. attached to the surface of the light-receiving surface. It is configured to output two systems of electrical signals with different levels depending on the position of the light incident on the light receiving surface.
That is, the light-receiving element 16 is a PIN-type position detection element composed of three layers of P, I, and N, and the light-receiving surface is composed of the P layer, which is a resistive layer.
Electrodes are provided at both ends in the vertical direction of the figure. 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, if the resistance between both electrodes is R, and the resistances between the point of incidence and each electrode are R ₁ and R 2 , currents i ₁ and _{i 2 expressed} by the following equations are output from each electrode.

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 ) From the above equations (1) and (2), the output voltages V _A and V _B of each electrode of the light receiving element 16 are expressed by the following equations.

V _A = i ₁ × R ₁ ... (3) V _B = i ₂ × R ₂ ... (4) Therefore, the light reflected from the workpiece 22 passes through the reference transmission line 102A to the center of the light receiving surface of the light receiving element 16. Signals of different levels are output from each electrode when the reflected light enters the end of the light receiving surface of the light receiving element 16 via the transmission line 102B.

If there is no dust attached to the surface of the workpiece 22, the laser beam is reflected on the surface of the workpiece 22,
The light is transmitted through the reference transmission path 102A and is incident on the light receiving surface _X0 of the light receiving element 16.

On the other hand, when the dust 34 with a height h is attached to the surface of the workpiece 22, the laser beam is reflected at the upper part of the dust 34, so the reflected light is transmitted through the transmission path 102B to the light-receiving surface X of the light-receiving element 16. Inject at position ₁ . Here, the positional relationship between x ₀ and x ₁ is x ₁ = x ₀ + 2h
becomes. Then, the two systems of electrical signals from the light receiving element 16 are outputted as signals shown in a and b in FIG.

The arithmetic section 18 is composed of amplifiers 36 and 38 and an arithmetic unit 40. The amplifiers 36 and 38 amplify the output signals V _A and V _B of the light receiving element 16 to predetermined levels V _A ′ and V _B ′, respectively, and supply the amplified signals to the arithmetic unit 40 . The arithmetic unit 40 calculates a signal obtained by dividing the sum of the output signals V _A ′ and V _B ′ of the amplifiers 36 and 38 (V _A ′ + V _B ′) and the subtracted signal (V _A ′−V _B ′). It is configured to output (V _A ′−V _B ′/V _A ′+V _B ′)Vout. Therefore, when the signals shown in a and b of FIG. 4 are supplied to the arithmetic unit 40, the output signal Vout of the arithmetic unit 40 has a waveform as shown in c of FIG. The signal is supplied to the determination unit 20.

As shown in FIG. 5, the determination unit 20 includes averaging circuits 41 and 42, level determination circuits 44 and 46,
It is composed of a logic operation circuit 48, a clock oscillator 50, and a timing logic circuit 52, and the output of the logic operation circuit 48 is supplied to a display 54.

Clock oscillator 50 is configured to generate clock pulses as shown in FIG. The timing logic circuit 52 generates a pulse signal with a predetermined period as shown in m in FIG. configured to supply. And the averaging circuit 41,
42. The logic operation circuit 48 operates to start the measurement operation at the rising edge of the output pulse of the timing logic circuit 52 and complete the measurement operation at the falling edge of the pulse.

The averaging circuit 41 receives the data from the arithmetic unit 40 c in FIG.
When the signal shown in FIG. 4 is given, this signal can be averaged and the signal waveform shown in d in FIG. That is, the averaging circuit 41 has the function of a low-pass filter that sequentially outputs a signal of the average value per unit time of the input signal, and when noise is superimposed on the output signal of the arithmetic unit 40, the noise component is removed. The output signal Vout of the arithmetic unit 40 is supplied to the level determination circuit 44 via the averaging circuit 41, and the level determination circuit 44 performs the following operation based on the output signal as shown in e of FIG. , the output level of the arithmetic unit 40 (a level equivalent to the level of the output signal of the averaging circuit 41 from which noise components have been removed, and the output level of the arithmetic unit 40 when something such as dust 34 is attached to the surface of the workpiece 22) When the output level of the arithmetic unit ₄₀ exceeds the reference level _V1 , f in FIG.
It is configured to supply the comparison output shown in FIG.

The averaging circuit 42 averages the output signal of the amplifier 32 and sends the averaged signal to the level determination circuit 46.
is configured to supply. When the averaging circuit 42 is supplied with the signal shown in g in FIG. 4 from the amplifier 32, this output signal is
It is possible to average the signal to a signal shown in h in the figure and supply this signal to the level determination circuit 46. That is, a signal from which noise components have been removed can be supplied to the level determination circuit 46. Then, the level determination circuit 46 determines the output level V _p of the amplifier 32 (a level equivalent to the level of the output signal of the averaging circuit 42 from which noise components have been removed) and the level of the output level V p of the amplifier 32 (equivalent to the level of the output signal of the averaging circuit 42 from which noise components have been removed) A second reference level V ₂ is determined as the output level of the light receiving element 14 when a defect such as a scratch occurs on the surface of the workpiece 22.
When the output level V _p of the amplifier 32 is less than the reference level V ₂ , the comparison output as shown in j in FIG. 4 is supplied to the logic operation circuit 48.

The logic operation circuit 48 includes the level determination circuits 44 and 4.
The measurement result for the workpiece 22 is determined based on the output signal of 6, and the determined output is supplied to the display 54.

For example, as shown in FIG.
When the output level Vout of the light-receiving element ₁₄ , that is, the output level _Vp of the amplifier 32, is less than the second reference level _V2 , scratches etc. may appear on the surface of the workpiece 22. It is determined that a defect has occurred, and a signal shown at k in FIG. 4 is applied to the display 54, thereby causing the display 54 to display that a defect has occurred on the surface of the workpiece 22.

Further, when the output level Vout of the arithmetic unit 40 exceeds the first reference level _V1 and the output level _Vp of the amplifier 32 is less than or equal to the second reference level _V2 , objects such as dust 34 are present on the surface of the workpiece 22. It is determined that something has adhered to the surface of the workpiece 22, and the same signal as shown in f in FIG.

Further, when the output level Vout of the arithmetic unit 40 is below the first reference level _V1 and the output level _Vp of the amplifier 32 exceeds the second reference level _V2 , it is determined that the workpiece 22 is a good product. Then, this judgment result is given to the display device 54, and the display device 54 displays that the workpiece 22 is a non-defective product.

In this embodiment, when measuring the surface defects of the workpiece 22, it is possible to check whether there is something attached to the surface of the workpiece 22, whether there is a defect on the surface of the workpiece 22, or whether the workpiece 22 is a good product. Since it is possible to determine whether or not the workpiece 22 is present or not, and display each determination result on the display 54, it is possible to avoid determining a non-defective product as a defective product due to dust etc. attached to the workpiece 22. There is no need to re-inspect, and there is no need to install a cleaning device in the previous process, so it is possible to improve yield, reduce the number of re-inspections, and reduce equipment investment.

Further, according to the embodiment, the workpiece 2 can be visually inspected.
Since the surface defects of the workpiece 22 can be reliably measured without inspecting the surface defects of the workpiece 22, the efficiency of the measurement work can be improved and the quality can be improved.

Further, in the embodiment, the first reference level V ₁ ,
The second reference level V ₂ is set to the light receiving element 14,
By floating according to the output level of the light receiving elements 14, 16, the light receiving elements 14, 16 may be caused to float due to deterioration of the laser oscillator 24, dirt on the light emitting lens 26, surface condition of the workpiece 22, deterioration of the light receiving elements 14, 16, etc. 16
Even if the output level of the workpiece 22 fluctuates, it is possible to reliably and accurately measure surface defects on the workpiece 22.

〔Effect of the invention〕

As explained above, according to the present invention, the surface of the object to be measured is irradiated with light, and the reflected light of the light irradiated to the surface of the object to be measured is divided into two transmission lines and transmitted. Each system of light is incident on multiple light receiving elements, and based on the output level of each light receiving element, it is possible to determine whether the object to be measured is a good product or whether something has adhered to the surface of the object to be measured.
Alternatively, since it is determined whether or not a defect has occurred on the surface of the object to be measured, it is possible to reliably measure surface defects of the object to be measured, improving work efficiency in surface defect measurement, and It is possible to improve the quality of the product, and furthermore, since a washing machine in the previous process is not required, there is an excellent effect that equipment costs can be reduced.

[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 output level V _p of the amplifier 32 and the moving direction X of the workpiece, FIG. 3 is a diagram for explaining the configuration of the light receiving element 16 shown in FIG. are waveform diagrams for explaining the operation of the device shown in FIG. 1, FIG. 5 is a configuration diagram for explaining the configuration of the determination section shown in FIG. 1, and FIG.
, the output level V _p of the arithmetic unit 40, and the output level Vout of the arithmetic unit 40
FIG. 3 is a diagram showing the relationship between the direction of movement of the workpiece and the moving direction X of the workpiece. DESCRIPTION OF SYMBOLS 10... Light emitting part, 12... Transmission part, 14, 16... Light receiving element, 18... Arithmetic part, 20... Judgment part, 24... Laser oscillator, 26... Light emitting lens, 28... Light receiving lens, 30... Beam splitter, 32, 36, 38
...Amplifier, 40...Arithmetic unit, 41, 42...Averaging circuit, 44, 46...Level judgment circuit, 48...Logic operation circuit, 54...Display device.

Claims (1)

[Claims] 1. A light projection section that irradiates light onto the surface of the object to be measured, and a transmission section that collects the reflected light of the light irradiated onto the surface of the object to be measured, divides this light into two transmission lines, and transmits it. , a first photoelectric conversion unit that receives light transmitted through the one transmission path and outputs an electrical signal at a level corresponding to the amount of received light; and a reference transmission path that transmits the light transmitted through the other transmission path. The second transmitter has a light-receiving surface capable of receiving light that is transmitted through a transmission path that is deviated from the reference transmission path and light that is transmitted through a transmission path that is deviated from the reference transmission path, and outputs two systems of electrical signals with different levels depending on the position of the light incident on this light-receiving surface. a photoelectric conversion unit; and a calculation unit that receives electrical signals from each system of the second photoelectric conversion unit, calculates a ratio of the levels of the electrical signals of the two systems, and outputs a signal of the determined ratio;
The output level of the calculation section is compared with a first reference level determined as the output level of the calculation section when an object adheres to the surface of the object to be measured, and the output level of the first photoelectric conversion section and the measurement object are compared. Compare the output level of the first photoelectric conversion unit with a second reference level determined as the output level of the first photoelectric conversion unit when an object adheres to the surface of the object or when a defect occurs on the surface of the object to be measured, and compare the results of these comparisons. a determination unit that determines the measurement result of the object to be measured based on the measurement result and generates a determination output, and the determination unit is configured such that the output level of the calculation unit is equal to or lower than a first reference level and the output level of the first photoelectric conversion unit is It is determined that a defect has occurred on the surface of the object to be measured when the output level is below the second reference level, and when the output level of the calculation section exceeds the first reference level and the output of the first photoelectric conversion section is determined. When the level is below the second reference level, it is determined that an object has adhered to the surface of the object to be measured, and when the output level of the calculation section is below the first reference level and the first
A surface defect measuring device characterized in that when the output level of the photoelectric conversion section exceeds a second reference level, it is determined that the object to be measured is a non-defective product, and outputs are generated according to each determination result.