JPH08334471A - Optical inspecting device for work - Google Patents

Abstract

PURPOSE: To highly sensitively and precisely detect a fine flaw, a distortion, etc., formed on the surface of a work by an optical detection means. CONSTITUTION: A light projecting fiber 13 and two light receiving fibers 14a, 14b positioned in the adjacent of this light projecting fiber 13 are bound in each fiber bundle 12 of a plurality of fiber bundles arranged in an array state in an inspecting optical end part 11. An inspecting light emitted from the projecting fiber 13 of each fiber bundle is cast on the surface of a flat work (W) relatively moving in relation to the optical end part 11. After the reflection light reflected from the surface of the flat work (W) is made incident on two light receiving fibers 14a, 14b respectively, it is emitted from respective light receiving fibers 14a, 14b to a photodiode provided in an inspective arithmetic part of an arithmetic device so that the reflection quantity is converted into voltage. Existence/nonexistence of flaws or a distortion, etc., formed on the surface of the flat work (W) is inspected based on output voltage of the two photosensors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical inspection device for a work for inspecting the presence or absence of fine scratches on the work surface or the distortion.

[0002]

2. Description of the Related Art Generally, fine scratches on a work surface,
Alternatively, there is an optical inspection device as a non-contact type inspection device for inspecting the adhesion state of minute foreign matter. This optical inspection device
As shown in FIG. 7, the inspection light emitted from the light source 1 such as a light emitting diode is condensed on the surface of the work 3 through the objective lens 2, and the reflected light is included at an included angle with respect to the optical axis of the inspection light. The photosensor 5 receives the light through another objective lens 4 arranged at the position α, and compares the reflected light amount (output voltage of the photosensor) with a threshold level set based on the property of the surface of the work 3. Then, the surface of the work is inspected for scratches, presence of foreign matter, distortion, and the like. That is, when the work surface is flat, the light reflected from the work surface is totally reflected in the photosensor direction, and
If scratches, foreign matter, etc. adhere to the work surface, or if distortion occurs, the reflected light is scattered or deviated, so that the amount of reflected light received by the photosensor 5 decreases. As a result, when the intensity (output voltage) of the reflected light detected by the photosensor changes and the output voltage of the photosensor is lower than the threshold level, it is determined that the work surface has a scratch or the like.

[0003]

However, in the conventional optical measuring device, since the light emitting system and the light receiving system are arranged at positions close to the work, the sandwiching angle α between them is the same as the light source. It is determined by the shape of the photo sensor.
Therefore, there is a limit to narrowing the included angle α.
Further, it is extremely difficult to detect minute scratches, distortions, and the like only by a change in the output voltage of one photosensor, and if the detection sensitivity is simply increased as a countermeasure, erroneous detection easily occurs.

Therefore, in the conventional optical inspection apparatus composed of a light emitting element and a light receiving element, a glass substrate such as a liquid crystal display,
It is difficult to detect minute scratches formed on the surface of silicon wafers, ceramic substrates, etc. used for semiconductors, etc., or adhesion of foreign matter that is difficult to see with the naked eye, and slight distortion with high accuracy. there were.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical inspection device for a work which can detect fine scratches, distortions, etc. formed on the surface of the work at low cost with high accuracy.

[0006]

In a first optical inspection device for a work according to the present invention, an inspection optical tip is provided on the surface of the work so as to be relatively movable, and the inspection optical tip is inspected from a light source. At least one tip of a fiber bundle formed by binding one light projecting fiber for emitting light to the work surface and a plurality of light receiving fibers for receiving the reflected light of the inspection light from the work surface. The plurality of light-receiving fibers arranged in the fiber bundle are divided into two light-receiving fiber groups, and photosensors are respectively arranged at the emission ends of the respective light-receiving fiber groups. , The other photosensor is connected to the inspection operation unit via an inversion circuit, and the inspection operation unit is connected to the output voltage from the one photosensor and the other photosensor via the inversion circuit. of And the difference between the force voltage is compared with the threshold level set in advance, and characterized in that to detect the presence or absence of scratches in the workpiece surface.

In the second optical inspection device for a work according to the present invention, the inspection optical tip is provided on the surface of the work so as to be relatively movable, and the inspection light from the light source is directed to the surface of the work. At least one tip end of a fiber bundle formed by binding one emitting light emitting fiber and a plurality of light receiving fibers for receiving the reflected light of the inspection light from the work surface is provided, and The plurality of light-receiving fibers provided in the fiber bundle are divided into a plurality of light-receiving fiber groups, and photosensors are respectively provided at the output ends of the respective light-receiving fiber groups. It is characterized in that it is connected to an inspection calculation unit for detecting the distortion of the work surface based on the difference.

[0008] In a preferred aspect of the present invention, the inspection optical tip in the first and second workpiece inspection devices is composed of a fiber array in which a plurality of the fiber bundles are arranged.

[0009]

In the optical inspection device for the first work, the inspection light from one projection fiber in at least one fiber bundle provided at the inspection optical tip is opposed to the inspection optical tip. Is emitted to the surface of the workpiece that moves relatively, and the reflected light enters the plurality of light receiving fibers of the fiber bundle. Then, the reflected light emitted from each of the light receiving fibers is received by a photosensor opposite to the light emitting ends of the two light receiving fiber groups that divide the light receiving fibers, and the amount of the reflected light is converted into a voltage. Then, the difference between the output voltage from one photosensor and the voltage obtained by inverting the output voltage from the other photosensor is obtained, and the difference voltage is compared with a preset threshold level to scratch or debris the work surface. Inspect for adherence.

In the optical inspection device for the second work, the inspection light from one projection fiber in at least one fiber bundle provided at the inspection optical tip is opposed to the inspection optical tip. Is emitted to the surface of the workpiece that moves relatively, and the reflected light enters the plurality of light receiving fibers of the fiber bundle. Then, the reflected light emitted from each of the light receiving fibers is received by a photosensor opposite to the emission end of each light receiving fiber group that divides each of the light receiving fibers in a predetermined manner, and the amount of the reflected light is converted into a voltage, which is then inspected. The difference between the output voltages of the photosensors is calculated by the arithmetic unit, and the distortion of the work surface is inspected based on the difference voltage.

Further, in the above-mentioned first and second optical inspection devices for works, the inspection optical tip portion is constituted by a fiber array in which a plurality of the fiber bundles are arranged, so that a relatively moving work surface is formed. It can be inspected column by column.

[0012]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows a flat plate-shaped work W and an inspection optical tip portion 11 of an inspection device which is opposed to the flat plate-shaped work W. The flat work W is a glass substrate of a liquid crystal display, a ceramic substrate, a light receiving surface of a solar cell, or the like, and is placed on a table (not shown) that is movable relative to the inspection optical tip 11.

The inspection optical tip portion 11 is a fiber array in which a plurality of sets of fiber bundles 12 are arranged in a row in the width direction of the flat work W, and each fiber bundle 12 constituting this fiber array is , One light projecting fiber 13 and two light receiving fibers 14a and 14b which are bound together in a state of being in contact with each other. Further, as shown in FIG. 2, the objective optical system 15 is attached to the tip of each fiber bundle 12.
Is mounted, and the surface of the flat work W is exposed on the focal point of the objective optical system 15.

On the other hand, as shown in FIG. 3, the proximal ends of the fiber bundles 12 face the corresponding computing devices 21. The arithmetic unit 21 is composed of a light source unit 21A and an inspection arithmetic unit 21B, and the light source unit 21A faces the incident end of the light projecting fiber 13. The light receiving fibers 14a and 14b are composed of two light receiving fiber groups 16
a, 16b, and each of the light receiving fiber groups 16a,
The emission end of 16b faces the inspection calculation unit 21B. In this embodiment, since there are two light receiving fibers, one light receiving fiber 14a and 14b corresponds to the light receiving fiber groups 16a and 16b in a one-to-one relationship, but three light receiving fibers are used. When there are more than one (preferably even number), the individual light receiving fibers are connected to the light receiving fiber group 16a,
16b is appropriately divided (for example, if there is an even number of lines, divided into ½ lines), and the inspection calculation unit 21B is exposed.

The light source section 21A includes an LED driver 22.
Is provided to the light emitting diode 23 which emits light in response to the drive signal from the LED driver 22,
The entrance ends of are opposite to each other. Also, the inspection calculation unit 21B
, Photosensors 24a and 24b are respectively installed at the emission ends of the respective light receiving fiber groups 16a and 16b. Each of the photosensors 24a and 24b includes an amplifier circuit 25a and 2a.
5b, and one amplifier circuit 25a is connected to one input terminal of the differential amplifier circuit 28. or,
The other amplifier circuit 25b is connected to an analog switch 26 such as an analog multiplexer. The analog switch 26 has a two-channel configuration, one output terminal is connected to the other input terminal of the differential amplifier circuit 28 via an inverting circuit 27, and the other output terminal is the other of the differential amplifier circuit 28. It is directly connected to the input terminal of. In addition,
The analog switch 26 selects one of the channels in a time-divisional manner or arbitrarily according to a control signal output from a control device (not shown). Also, the differential amplifier circuit 2
At 8, the voltage output is proportional to the difference between the two input signals.

Further, the output terminal of the differential amplifier circuit 28 is connected to one input terminal of the comparison circuit 29, and the threshold level setting circuit 30 is connected to the other input terminal. In the comparison circuit 29, the differential amplifier circuit 2
The difference voltage output from 8 is compared with the threshold level output from the threshold level setting circuit 30, and the result is output to the post-processing circuit 31 including a counter and the like. On the other hand, the other output terminal of the differential amplifier circuit 28 is connected to a post-processing circuit 32 including an A / D conversion circuit. The threshold level is the flat work W
Is a threshold value for determining the presence or absence of scratches Wo (or adherence of foreign matter) on the surface of the sheet, and is set based on the surface properties of the flat work W to be inspected.

In the inspection / calculation section 21B, the flat work W is changed by the switching operation of the analog switch 26.
The presence or absence of scratches Wo (or adherence of foreign matter) on the surface and the distortion θ are selectively inspected. That is, when the output signal from the amplifier circuit 25b is output to the inversion circuit 27 by the analog switch 26, it is inspected for the presence of scratches Wo (or adherence of foreign matter) on the surface of the flat work W, and The result is processed by the post-processing circuit 31. When the output signal from the amplifier circuit 25b is directly output to the differential amplifier circuit 28, the distortion .theta.
Is checked and the result is output to the post-processing circuit 32 including the A / D conversion circuit.

Next, the operation of the embodiment having the above structure will be described. A flat plate-shaped work W is placed on a table (not shown) of the inspection device, and the table is relatively moved to transfer the flat plate-shaped work W to the inspection optical tip 11. From the light projecting fiber 13 provided in each fiber bundle 12 of the inspection optical tip portion 11, the inspection light is emitted from the light emitting diode 23 provided in the light source portion 21A of the arithmetic unit 21 shown in FIG. The surface of the flat plate-shaped work W is irradiated with the light through.

On the other hand, when the inspection light reflected from the surface of the flat plate-shaped work W is incident on the two light receiving fibers 14a and 14b via the objective optical system 15,
The reflected light is emitted from the output ends of the light receiving fibers 14a and 14b, that is, from the output ends of the light receiving fiber groups 16a and 16b, which correspond to each other in the present embodiment, in the arithmetic unit 21.
Photosensors 24a, 2 provided in the inspection calculation unit 21B
After being received by 4b, the amount of reflected light is converted into a voltage, and then amplified by the amplifier circuits 25a and 25b in a predetermined manner. The reflected light causes scratches (or adhered matters) W on the surface of the flat plate-like work W.
If o is present, it is scattered, so the amount of light received by each of the photosensors 24a and 24b decreases, and the amplifier circuit 25
The voltage output from a and 25b also becomes a low value.

The output voltage from the one amplification circuit 25a is output to one input terminal of the differential amplification circuit 28, and the output voltage from the other amplification circuit 25b is passed through the analog switch 26 and is now output. If the inspection item is an inspection for the presence or absence of scratches Wo or the like on the surface of the flat work W, it is output to the inverting circuit 27, and the current inspection item is an inspection for the distortion θ of the surface of the flat work W. If it is, the signal is directly output to the other input terminal of the differential amplifier circuit 28.

In the following description, the case of inspecting the surface of the flat work W for the presence of scratches Wo and the like will be described first, and then the case of inspecting the strain θ of the surface of the flat work W will be described.

After the output voltage from the amplifier circuit 25b is inverted by the inversion circuit 27 through the analog switch 26,
When input to the other input terminal of the differential amplifier circuit 28, the amplifier circuit 25 is input to one input terminal.
A voltage proportional to the difference from the output voltage from a is output.
The two output voltages input to the amplifier circuit 25a are obtained by photoelectrically converting the reflected light of the same inspection light reflected on the surface of the work W, so that one output voltage is inverted to output the two output voltages. By obtaining the voltage difference, the change in the output voltage is increased and the sensitivity is remarkably improved. The sensitivity of the difference voltage is normally about 0.2V, but 1.0 to 2.0V.
And grows.

The difference voltage output from the differential amplifier circuit 28 is input to one input terminal of the comparison circuit 29 and compared with the threshold level from the threshold level setting circuit 30 input to the other input terminal. To be done. This threshold level predicts the amount of increase in the differential voltage output from the differential amplifier circuit 28 when there is a minute scratch (or adhered matter) Wo on the surface of the work W, and the differential voltage The threshold value is set in advance so that it can be detected that the value has increased.

The comparison circuit 29 outputs an H signal to the post-processing circuit 31 when the difference voltage is above the threshold level, and an L signal when the difference voltage is below the threshold level. . In the post-processing circuit 31, the output signal from the comparison circuit 29 is read every predetermined time in synchronization with the movement amount of the flat plate work W, and the address of the memory corresponding to the movement amount of the flat plate work W is counted. Are sequentially designated by, and 1-bit data of the address is set when the H signal is output, and cleared when the L signal is output.

This inspection is executed for each arithmetic unit 21 connected to each fiber bundle 12, and the data stored in the memory of the post-processing circuit 31 provided in each arithmetic unit 21 is converted into a point coordinate system. By displaying and outputting the data, it is possible to sequentially inspect the presence or absence of scratches (or adhered matters) Wo on the surface of the work W and the positions of the scratches in column units.

On the other hand, the surface strain θ of the flat work W
When inspecting, the voltage amplified by the amplifier circuit 25b from the analog switch 26 is the differential amplifier circuit 2
8 is directly output to the other input terminal. Then, the differential amplifier circuit 28 outputs a voltage proportional to the difference between the voltages output from the two amplifier circuits 25a and 25b to the post-processing circuit 32.

As shown in FIG. 2, for example, when the surface of the work W is distorted with an inclination θ in the upper right direction in the figure, the reflection direction of the inspection light emitted from the light projecting fiber 13 is deviated, and A large amount of light is reflected to the side of the light receiving fiber 14a, and the amount of reflected light to the other light receiving fiber 14b decreases accordingly. As a result, the amount of reflected light emitted from the light receiving fiber 14a and received by the photosensor 25a becomes P + δP (δP: the amount of change with respect to the inclination θ) when the amount of light received in the flat state is P, and the other light is received. The amount of reflected light received by the other photosensor 25b through the fiber 14b is P
−δP. Since the voltage output from the differential amplifier circuit 28 is a voltage proportional to the difference between the light amounts (P + δP, P−δP), the surface of the flat work W is flat (θ).
= 0), the value is close to 0 V, and the slope θ
When there is a distortion of, the voltage corresponding to + 2δP or -2δP is output to the post-processing circuit 32 depending on the inclination direction.

In the post-processing circuit 32, the voltage output from the differential amplifier circuit 28 is A / D-converted, and this data is stored in the memory in synchronization with the movement amount of the flat plate-shaped work W at predetermined intervals. Store. Then, by expressing the inspection result in the point coordinate system of each arithmetic unit 21, it is possible to grasp the degree of distortion of the entire surface of the work W by a specific number.

When inspecting for any scratches or distortions on the surface of the flat work W, the two light receiving fibers 14a, 1 are used.
Since 4b is placed opposite to the work surface at a position extremely close to each other, a change in color tone, a change in distance, and the like cancel each other out.

Further, in the present embodiment, one light projecting fiber 13 and two light receiving fibers 14a and 14b are bundled in an array having the smallest cross-sectional area, but the size of the work to be inspected. , And the state can be appropriately set. For example, as shown in FIG.
4a and 14b may be disposed on both sides of the light projecting fiber 13, and as shown in FIG. 5, four light receiving fibers 14a to 14d with the light projecting fiber 13 as the center.
May be arranged in a cross shape, or as shown in FIG. 6, a plurality of light receiving fibers 14a to 14f may be arranged around the light projecting fiber 13. In this case, the output end side of each of the light receiving fibers 14a to 14d or 14a to 14f is divided into two light receiving fiber groups 16a and 16b, and is guided to the inspection operation unit 21B of the operation device 21 shown in FIG. Get burned.

[0031]

As described above, according to the present invention,
The inspection light from the light source is emitted to the work surface via the light projecting fiber, and the reflected light is guided to the photosensor via the light receiving fiber. Therefore, it becomes possible to detect minute scratches or distortions on the surface of the work.

Further, the inspection light emitted from one light projecting fiber is reflected by the work surface and is incident on a plurality of light receiving fibers, and each of the incident reflected light is received separately. Since the photo sensor receives light for each fiber group, it becomes possible to detect minute scratches, distortions, etc. formed on the surface of the work with high sensitivity, and not only the inspection accuracy can be significantly improved. It is possible to realize cost reduction.

[Brief description of drawings]

FIG. 1 is a plan view of a work and an inspection optical tip portion taken along the line II of FIG.

FIG. 2 is a side view taken along arrow A in FIG.

FIG. 3 is a circuit diagram of an arithmetic unit.

FIG. 4 is a cross-sectional view of a fiber bundle according to another aspect.

FIG. 5 is a cross-sectional view of a fiber bundle according to another aspect.

FIG. 6 is a cross-sectional view of a fiber bundle according to another aspect.

FIG. 7 is a schematic explanatory view of a conventional optical inspection device.

[Explanation of symbols]

 Reference numeral 11 ... Inspection optical tip portion 12 ... Fiber bundle 13 ... Projection fibers 14a to 14f ... Receiving fibers 16a, 16b ... Receiving fiber group 21A ... Light source 21B ... Inspection computing unit 24a, 24b ... Photo sensor W ... Workpiece

Claims (3)

[Claims] 1. An inspection optical tip is provided on a surface of a work so as to be relatively movable, and one optical projection fiber for emitting inspection light from a light source to the surface of the work is provided at the inspection optical tip, and the inspection. At least one end portion of a fiber bundle formed by binding a plurality of light receiving fibers that receive reflected light of light from the work surface
The plurality of light receiving fibers provided in this fiber bundle are divided into two light receiving fiber groups, and photosensors are respectively provided at the emission ends of the respective light receiving fiber groups. Directly connected to the operation unit, the other photosensor is connected to the inspection operation unit via an inversion circuit, the inspection operation unit, the output voltage from the one photosensor and the other photosensor via the inversion circuit An optical inspection device for a work, wherein the presence or absence of scratches or the like on the work surface is detected by comparing the difference between the output voltage from the work and a preset threshold level. 2. An inspection optical tip is provided on the surface of the work so as to be relatively movable, and one optical projection fiber for emitting inspection light from a light source to the surface of the work is provided to the inspection optical tip, and the inspection. At least one end portion of a fiber bundle formed by binding a plurality of light receiving fibers that receive reflected light of light from the work surface
The plurality of light receiving fibers provided in the fiber bundle are divided into a plurality of light receiving fiber groups, and photosensors are respectively provided at the exit ends of the respective light receiving fiber groups. An optical inspection device for a work, which is connected to an inspection calculation unit for detecting the distortion of the surface of the work based on a difference in output voltage of each photo sensor. 3. The optical inspection device for a workpiece according to claim 1, wherein the inspection optical tip portion is formed of a fiber array in which a plurality of the fiber bundles are arranged.