JPH0527060B2 - - 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 type of conventional equipment irradiates the surface of the object to be measured with light, receives the reflected light of the irradiated light on the surface of the object to be measured, and detects defects on the surface of the object based on the amount of received light. It was configured to measure whether or not it occurred. 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 inspect defective products, or to 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. Furthermore, JP-A-57-13340 and JP-A-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. 2 with different levels depending on the position of the optical axis.
a second photoelectric conversion unit that outputs a system electrical signal;
A calculation unit that calculates the level ratio of the electrical signals of each system of the output of the second photoelectric conversion unit and outputs a signal according to the calculated ratio; and a calculation unit that samples the output signal of the calculation unit at a predetermined timing. a first detection section that sequentially captures the level of the detected signal according to the sampling period and outputs a first defect signal when the signal at each timing exceeds the level at the previous timing; and an output signal of the first photoelectric conversion section. a second detection unit that samples the signal at a predetermined timing, sequentially captures the level of the sampled signal according to the sampling period, and outputs a second defect signal when the signal at each timing exceeds the level at the previous timing; , 1st
Each output signal of the calculation unit and the first photoelectric conversion unit is compared with a plurality of reference levels under the condition that either one of the defect signals of the first defect signal and the second defect signal is input, and the results of these comparisons are calculated. a determination unit that determines a measurement result for the object to be measured based on and outputs the determination result, and the determination unit determines that the level of the output signal of the first photoelectric conversion unit indicates that the object to be measured is non-defective. Unlike the first reference level, which is set in association with the output signal of the first photoelectric conversion section as the level when the output signal of the calculation section is calculated as the level when the object to be measured is a good product. When the level of the output signal of the first photoelectric conversion unit is different from the second reference level set in association with the output signal of the first photoelectric conversion 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 unit is set to the first reference level. When the level of the output signal of the calculation unit matches the second reference level, it is determined that a defect such as a scratch has occurred on the surface of the object to be measured, and the output signal of the first photoelectric conversion unit is The first level is
, and when the level of the output signal of the arithmetic unit matches a second reference level, it is determined that the object to be measured is a non-defective product. [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 light from a first light projecting section, and the side surface of the workpiece 14 is irradiated with light from a second projecting section. Light from the light section is irradiating. 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 work 14 and the optical scanner 1.
8, the side surface of the workpiece 14 is irradiated via the slit 22, the lens 24, and the reflecting mirror 26. The optical scanner 18 has a measurement unit 28.
The structure is such that it can be rotated within an angle range of θ1 by a drive signal S output from a drive signal S. For this reason,
When the optical scanner 18 rotates within the range of angle θ1, the optical axis of the laser beam irradiated to the lens 24 through the slit 22 changes within the range of angle θ2 and is irradiated onto the reflecting mirror 26, which 14 sides are irradiated. Furthermore, when the optical scanner 18 rotates within the range of angle θ1, the optical axis of the light irradiated onto the lens 20 changes within the range of θ3 and is irradiated onto the surface of the workpiece 14. 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, and on the other hand,
If something is attached to the surface of the workpiece 14 or if there is a defect such as a scratch on the surface of the workpiece 14, diffused reflection will increase and the amount of light received will decrease.
The level is lower than the voltage _V1 . That is, the level of the output signal V _S of the amplifier 34 decreases when something adheres 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 light that has passed through the front surface side of the workpiece 14 out of the laser light irradiated onto the side surface of the workpiece 14, and determines the position of the received laser light. It is configured to output two systems of electrical signals with different levels depending on the level. When the side surface of the workpiece 14 is irradiated with a laser beam, as shown in FIG.
102 enters the light receiving element 38, but the workpiece 14
If dust 40 or the like adheres to the surface of the laser beam 102, 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, in order to easily determine whether dust or the like has adhered to the surface of the work 14, the laser light that has passed through the front surface of the work 14 out of the laser light irradiated onto the side surface of the work 14 is used. Light is received by the light receiving element 38, and two systems of electrical signals having different levels are outputted depending on the position of the laser light received from the light receiving element 38. The light-receiving element 38 is a PIN type position detection element composed of three layers of P, I, and N. 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, 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 ) 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 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 the arithmetic unit 48 amplifies the output signals V A and V B of the amplifiers 44 and 46, respectively. _A ′,
A signal V _ADD =V _A ′+V _B ′ is obtained by adding 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 enter the light receiving element 38.
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 becomes 3.
It will be about ~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. As shown in FIG. 5, the detection unit 50 includes an oscillator 52, a timing circuit 54, and a comparator 5.
6, 58, setting section 60, 62, and gate 6
4, 66, 68, 70, analog switch 72,
74, 76, 78, averaging circuit 80, 82, 8
4, 86, multiplication circuit 88, 90, 92, 94, sample hold circuit 96, 98, 100, 10
2. Analog switch 104, 106, 108,
110, and comparators 112 and 114. The output signal of the oscillator 52, which generates the pulse signal, is supplied to a timing circuit 54. The timing circuit 54 is configured to output a clock signal Cl synchronized with the output pulse of the oscillator 52 and timing signals F and B when the start signal ST from the measurement unit 28 is applied. Clock signal Cl and timing signals F and B are supplied to the measurement unit 28 and motor driver 120, respectively, and timing signals F and B are supplied to one input terminal of AND gates 64, 66, 68 and 70, respectively. And gate 64, 66, 68, 70
are configured to generate an output signal when both the output signals from the comparators 56 and 58 and the timing signals F and B from the timing circuit 54 are applied. Here, in this embodiment, the laser beams irradiated onto the surface and side surfaces of the workpiece 14 are irradiated over a wide range, and the electric signals V _S and V _P based on these laser beams are also aligned with the optical axis of the laser beams. Since _the signals are output as _signals according to Each and gate from 64,6
6, 68, and 70. That is, levels corresponding to certain areas on the surface and side surfaces of the workpiece 14 are set in the setters 60 and 62, and among the signals V _S and V _P supplied to the comparators 56 and 58, the levels corresponding to certain areas on the surface and side surfaces of the workpiece 14 are set. Signal based on laser light irradiated to a certain area on the side
The comparators 56 and 58 are configured to output signals when only V _S and V _P are supplied to the comparators 56 and 58. When the signal is output from the AND gates 64, 66, 68, 70, the analog switches 72, 74, 7
The circuits 6, 78, 104, 106, 108, 110 are opened and the averaging circuits 80, 82, 8 are opened.
4, 86, and the signals outputted from multiplication circuits 88, 90, 92, and 94, respectively, are held by sample and hold circuits 96, 98, 100, and 102. That is, when the signal V _S is opened by the analog switches 72 and 74 in synchronization with the timing signals F and B, the signal V _S is applied to the averaging circuits 80 and 82 and the multiplication circuits 88 and 9, respectively, according to the timing.
0 to sample and hold circuits 96 and 98, and the sample and hold circuits 96 and 98 temporarily hold the level. This held level is then supplied to the comparator 112 when the circuits of the analog switches 104 and 106 are opened at the next timing. analog switch 10
The comparator 112 compares the signal V _S output from the amplifier 34 with the level output from the analog switches 104 and 106 at the timing when the circuit No. 4,106 is opened, and the output signal V _S from the amplifier 34 is compared with the level output from the analog switches 104 and 106. Level is analog switch 10
4, 106 is exceeded, a defect signal ai is output indicating that a defect has occurred on the surface of the workpiece 14. Also, for the signal V _P , similarly to the signal V _S , the signal V _P output from the calculation section 42 and the level output from the analog switches 108 and 110 are compared by the comparator 114, and the signal V P output from the calculation section 42 is compared with the level output from the analog switches 108 and 110. The level of the signal V _P
When the level exceeds the level output from 8, 110, it is determined that a defect has occurred on the surface of the workpiece 14, and a defect signal bi is output. In this way, the output signal V _P of the detection section 50 and the calculation section 42 and the output signal V _S of the amplifier 34 in this embodiment are
are sampled at predetermined timings,
It is configured to sequentially capture the levels of each signal V _S and V _P according to the sampling period, and output defect signals ai and bi when the level of any signal at each timing exceeds the level at the previous timing. There is. Each defect signal ai, bi is supplied to a measurement unit 28, respectively. Note that the multiplier circuits 88, 90, 92, and 94 are each equal to the averaging circuit 8.
Signal averaged by 0, 82, 84, 86
It functions as a circuit that shapes the waveforms of V _S and V _P , respectively. The measurement unit 28 is composed of a determining section and a driving section. Among these, the 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 120. Each drive signal S,
D _P is output in synchronization with timing signals F and B, respectively. That is, when the drive signal S synchronized with the timing signals F and B is supplied from the measurement unit 28 to the optical scanner 18, the timing signal F
When the optical scanner 18 is driven in synchronization with the timing signal B, the laser light emitted from the optical scanner 18 to the lenses 24 and 20 moves from the left side to the right side in the drawing, and the optical scanner 18 rotates in synchronization with the timing signal B. When driven, the beam light irradiated to the lenses 20 and 24 moves from the right side to the left side in the drawing. A plurality of reference levels are set in the determination section, and this determination section is configured to use the reference level and the output signal.
It is configured to compare V _S and V _P , determine the measurement result for the workpiece 14 based on the comparison results, and display the determination result on the display 122 . Among the reference levels set in the determination section, the first reference level is associated with the output signal V _S ,
The second reference level is set to the level when the workpiece 14 is a good product, that is, the level _V1 shown in FIG. It is set to correspond to the level when , that is, the level V2 shown in C in FIG. FIG. 6 shows an embodiment in which the measurement unit 28 is constituted by a microcomputer. In FIG. 6, the measurement unit 28 is the CPU 1
30, ROM132, RAM134, A/D converter 136, digital input/output circuit 138, digital output circuit 140, D/A converter 142,
It is composed of a multiplexer 144,
CPU130, ROM132, RAM134, A/
D converter 136, digital input/output circuit 13
8, a digital output circuit 140 and a D/A converter 142 are connected to each other by a bus line 146. The output signals V _S and V _P are each sent to multiplexer 1.
44 to the A/D converter 136. Measurement command M, origin command O, timing signals F, B, defect signals ai, bi, and clock signal Cl are each supplied to a digital input/output circuit 138. Further, data regarding the first and second reference levels described above is stored in the ROM 132. The CPU 130 is configured to take in data based on the output signals V _S and V _P , judge the measurement results for the work 14, and output the judgment results to the display 122 via the digital output circuit 140. has been done. Further, the drive signal S for driving the optical scanner 18 is sent to the D/A converter 1.
32. Note that the drive signal S is output as a triangular wave signal. In the device according to the embodiment configured as described above, when the drive signal S is given to the optical scanner 18 from the measurement unit 28, the optical scanner 18 rotates within the range of angle θ1, and the laser beam from the laser oscillator 16 is rotated. is irradiated onto the surface and side surfaces of the workpiece 14 via the lenses 20 and 24. On the other hand, at this time, the drive signal D _P is given to the motor driver 120 together with the drive signal S, 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 receives signals V _S , V _P based on the laser light irradiated onto the surface and side surfaces of the workpiece 14 .
are given for each scan at a timing synchronized with the movement of the optical scanner 18. When the output signals V _S and V _P are applied to the measurement unit 28 for each scan, the measurement unit 28 compares the output signals V _S and V _P with the first and second reference levels, and calculates the comparison between them. Based on the results, a process is performed to determine the comparison result for the work 14 and output the determination result. That is, as shown in FIG. 7a, the output signal
V _S and the first reference level V1 are different, and the output signal
When V _P and the second reference level V2 are different, it is determined that objects such as chips and dust have adhered to the surface of the workpiece 14, and as shown in FIG. 7b, the output signal is
The level of V _S is different from the first reference level V1,
When the level of the output signal V _P matches the second reference level V2, it is determined that a defect such as a scratch or a blowhole has occurred on the surface of the workpiece 14, and the output signal is adjusted as shown in c in FIG. The output level of the signal V _S is the first
When the level of the output signal V _P matches the second reference level V1, it is determined that the workpiece 14 is a good product. These determination results are displayed on the screen of the display 122 via the digital output circuit 140. As described above, in this embodiment, the measurement results for the workpiece 14 are displayed on the screen of the display 122, so that by viewing the measurement results displayed on the screen of the display 122, the operator can: Work 1
Is there a scratch etc. on the surface of workpiece 14?
Is something attached to the surface of the workpiece 14?
It is possible to easily check whether the product is of good quality or not. In addition, in this example, scratches,
A workpiece master with blowholes etc. formed on its surface is measured, and as shown in Figure 8, the flaws and blowhole size are determined relative to the laser beam angle θ1.

〔effect〕

As explained above, according to the present invention, beam light from a single light source is irradiated onto the surface and side surfaces of the object to be measured, and the reflected light from each surface is received by the respective light receiving elements. The output signal is sampled at a predetermined timing, the signal level at each timing is compared sequentially, and when the comparison result indicates the occurrence of a defect, a defect signal is generated, and only when a defect signal is generated, the output signal of each light receiving element is and the first and second reference levels, and the presence or absence of surface defects on the object to be measured is determined based on the comparison result. Therefore, surface defects on the object to be measured can be measured reliably and quickly, and the device can be made compact. can contribute to the development of

[Brief explanation of drawings]

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 laser beam angle 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 calculation section shown in the figure, FIG. 5 is a specific configuration diagram of the detection section shown in FIG. 1, and FIG. 6 is a diagram of the measurement unit 28 shown in FIG.
A to c in FIG. 7 is a diagram showing the relationship between the laser beam angle and the voltage, FIG. 8 is a diagram showing the relationship between the laser beam angle and the size of the defect, and FIG. 9 is a diagram showing the relationship between the laser beam angle and the size of the defect. 1 is a flowchart for explaining the operation of the apparatus shown in FIG. 12...Motor, 14...Work, 16...Laser oscillator, 18...Optical scanner, 2
0, 24, 30, 36... Lens, 28... Measurement unit, 32, 38... Light emitting element, 42... Calculation section, 50... Detection section, 122... Display device.

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 projector that sequentially irradiates the light toward the side surface; a first photoelectric converter that receives the reflected light of the light irradiated onto the surface of the object to be measured and outputs an electrical signal at a level corresponding to the amount of received light; , receives the beam light that has passed at least 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 generates two systems of electrical signals with different levels depending on the position of the optical axis of the received beam light. a second photoelectric conversion section that outputs 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 an output of the calculation section. A first detection unit that samples the signal at a predetermined timing, sequentially captures the level of the sampled signal according to the sampling period, and outputs a first defect signal when the signal at each timing exceeds the level at the previous timing. Then, the output signal of the first photoelectric conversion section is sampled at a predetermined timing, and the level of the sampled signal is sequentially fetched according to the sampling period.When the signal at each timing exceeds the level at the previous timing, the second photoelectric conversion section is A second detection section that outputs a defect signal, and each output signal of the calculation section and the first photoelectric conversion section on the condition that either one of the first defect signal and the second defect signal is input. a determination unit that compares each with a plurality of reference levels, determines a measurement result for the object to be measured based on the comparison results, and outputs the determination result, the determination unit comprising a first
The level of the output signal of the photoelectric conversion section is different from the first reference level that is set in association with the output signal of the first photoelectric conversion section as the level when the object to be measured is a good product, and the level of the output signal of the calculation section The level of the output signal is set as a level when the object to be measured is a non-defective product in correspondence with the output signal of the calculation section.
When the level of the output signal of the first photoelectric conversion section is different from the first reference level, 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 calculation section is different from the first reference level. When it matches the second reference level, 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 matches the first reference level, and the calculation section 1. A surface defect measuring device that determines that an object to be measured is a non-defective product when the level of the output signal matches a second reference level.