JPH0777497A - Surface flaw inspection method and device therefor - Google Patents

Abstract

PURPOSE:To provide a surface flaw inspection method capable of inspecting a flaw on a simpler principle and capable of surely detecting a flaw even when the position of an edge section to be inspected is fluctuated and to provide a surface flaw inspection device capable of realizing this inspection method with a simple structure at a low cost. CONSTITUTION:Uniform light is radiated from a light source 4 to a translucent object 1 to be inspected having a line-like edge section 3 so that the light is fed to two adjacent faces 1a, 1b forming the edge section 3 to be inspected. The transmitted light or the reflected light obtained in the range along the direction perpendicular to the line direction of the edge section 3 is received by a line light receiving sensor 5, and the light reception is made in sequence along the line direction of the edge section 3. A flaw is detected by a detection processing means 7 based on the information of the intensity distribution of the transmitted light or the reflected light thus received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface defect inspection method and apparatus for automatically inspecting a surface of a plate-shaped light-transmitting member, especially an edge portion thereof.

[0002]

2. Description of the Related Art Generally, an image output device such as an electrophotographic copying machine or a laser printer is equipped with a cleaning mechanism for removing residual toner and deposits adhering to the surface of its photosensitive drum. . The cleaning mechanism section normally presses a transparent blade made of polyurethane rubber against the rotating photosensitive drum so that the edge of the tip of the cleaning blade comes into contact with the cleaning blade to remove residual toner and adhered matters on the drum surface. It is supposed to be scraped off.
Therefore, if the edge of the cleaning blade has defects such as cracks, cracks, and adhesion of foreign matter, residual toner and deposits on the drum are not sufficiently removed, and streaky lines appear in the output image, or However, the defect causes a problem such as scratching of the drum surface, which causes malfunction. Further, even if a defect such as a minute “chip” of about 10 μm is used, in recent digital color copying machines, a minute toner of about several μm is used in order to improve image quality. There is a problem that a certain blade portion cannot remove minute toner.

Conventionally, the following techniques have been proposed as inspection techniques capable of automatically inspecting surface defects in such blades and the like. For example, a) JP-A-4-203956 discloses that an object to be inspected such as a developing blade is irradiated with light by a laser beam, and light transmitted through the object to be inspected or light reflected on the surface at that time is halved. It is divided into two directions by a mirror, one of which is received as a transmitted light component from which the diffused light component has been removed and is used to inspect for foreign substances and dirt that have absorptive property due to abnormal light intensity, and the other is received as a diffused light component and the light intensity A method and an apparatus for simultaneously detecting defects of multiple items by using it for inspection of irregularities and irregularities are shown. In this case, the entire surface of the object to be inspected is inspected by moving the object to be inspected by the moving means in a direction orthogonal to the irradiation direction of the irradiation light. Also, b) Japanese Patent Publication No. 58-41459
In the publication, as a method for inspecting a chip of an edge portion (ridge portion) in an optical component such as a cemented carbide bite chip or a glass prism, a laser beam is scanned across the edge portion of the inspected article, Measures the scanning time and length between the reference point and the edge defined on the surface or space other than the inspection item,
A method and an apparatus for detecting the presence and size of a defect by comparing it with a predetermined value (the laser light is scattered when there is a defect and the scanning time becomes longer than the predetermined value) are shown.

[0004]

However, the above-mentioned inspection technique a) scans the side surface of the blade, which is the object to be inspected, with laser irradiation light having a beam diameter of about 0.1 mmφ, so that the laser at the edge portion is scanned. It becomes difficult to distinguish scattered light that naturally occurs from light and scattered light that occurs due to edge defects, and in particular, defects such as chips may not be accurately detected. Further, as for the apparatus, there is a problem that the apparatus becomes large in size and costly because it requires a laser beam scanning means, a two-way division optical system and two light receivers.

On the other hand, in the above inspection technique b), when inspecting an object to be inspected such as a cleaning blade, the blade is in the state of being adhered to the sheet metal bracket, and the edge portion to be inspected The position of () is several hundreds of μm relative to (the reference position of) the metal plate bracket (for example,
However, there is a problem in that the distance between the reference point and the edge portion is not constant, which prevents accurate defect detection. Further, since the apparatus requires a laser beam scanning means and a complicated optical system therefor, there is a problem that the apparatus becomes large in size and high in cost as in the inspection technique a).

The present invention has been made in view of the above-mentioned problems, and defect inspection can be performed by a simpler principle, and the defect can be surely detected even if the position of the edge portion to be inspected changes. An object of the present invention is to provide a surface defect inspection method and a low-cost surface defect inspection device having a simple structure capable of realizing the inspection method.

[0007]

A surface defect inspection method according to the present invention is a method in which a light-transmissive inspection object having a line-shaped edge portion is formed by applying uniform light to an edge portion to be inspected. Irradiate the two surfaces so that they are incident, and receive transmitted light or reflected light obtained in a range along the direction orthogonal to the line direction of the edge part at that time and receive the light along the line direction of the edge part. The feature is that the defects are detected sequentially based on the information of the intensity distribution of the received transmitted light or reflected light.

Further, the surface defect inspection apparatus of the present invention includes a light source for irradiating uniform light so as to be incident on two adjacent surfaces forming an edge portion of an inspection target in a light-transmitting inspection object,
A line light receiving sensor that receives transmitted light or reflected light obtained in a range along a direction orthogonal to the line direction of the edge portion of the inspection target by light irradiation of the light source and sequentially receives the light along the line direction of the edge portion. And a detection processing unit that detects a defect based on a sensor signal indicating an intensity distribution of transmitted light or reflected light received by the line light receiving sensor.

[0009]

According to the present invention, two adjacent surfaces (for example, the upper surface and the upper surface thereof) forming the edge portion of the inspection object are held by inclining the inspection object by a predetermined amount with respect to the optical axis of the irradiation light. To the side surface adjacent to each other through the edge portion), and the transmitted light or reflected light obtained in the range along the direction orthogonal to the line direction is received, so that the edge portion serves as a boundary. As a result, a distribution of light intensity (contrast) can be obtained between two adjacent surfaces, but if there is a defect such as a chip at the edge at that time, the defective part will show different light transmission characteristics or reflection characteristics from the normal part. , Where there is a sharp change in the intensity distribution. By comparing the portion where the light intensity has changed with a normal light intensity distribution (signal waveform or the like), it can be detected as a defect. Then, by relatively moving the inspection object and the line light-receiving sensor along the line direction of the edge portion, it is possible to perform a defect inspection on the edge portion over the entire width of the inspection object.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the present invention,
FIG. 1 shows the structure of the surface defect apparatus, and FIG. 2 shows the surface defect inspection method by the apparatus. This embodiment shows a case of inspecting a defect in an edge portion of a cleaning blade of a copying machine or the like.

In FIG. 1 or 2, reference numeral 1 denotes a cleaning blade which is a translucent inspection object, and this blade 1 has a size of 220 mm (width) × 12 mm (height) ×
It has a flat plate shape of 2 mm (thickness) and is fixedly supported on the metal plate bracket 2 by adhesion or the like. In the blade 1, reference numeral 3 denotes an edge portion to be brought into pressure contact with the photosensitive drum of the copying machine, and at the same time, an edge portion to be inspected. Reference numeral 4 is a straight tube type white fluorescent lamp as a light source for uniformly irradiating the blade 1 with diffused light. Furthermore, 5
Is a line light receiving sensor in which m pixels 6 are vertically arranged in a row,
Reference numeral 7 denotes detection processing means for detecting a defect based on the sensor signal output from the sensor 5.

This inspection device is of a transmitted light type,
In a state in which the blade 1 is arranged so that the edge portion 3 to be inspected faces the line light receiving sensor 5 side and is inclined rearward about 10 to 20 ° with respect to the vertical direction of the optical axis direction x of the white fluorescent lamp 3. It is configured to be held and moved at a constant speed in the line direction y of the edge portion 3, that is, the width direction of the blade 1 by a conveying means (not shown).

Further, the line light receiving sensor 5 is installed so that the arrangement direction of the pixels 6 coincides with the direction z orthogonal to the line direction y of the edge portion 3, and among the transmitted light from the blade 1 generated by the light irradiation. The light emitted in the direction z orthogonal to the line direction y of the edge portion 3 can be received.

In such an inspection apparatus, the light intensity distribution of transmitted light can be obtained as follows.

First, when the irradiation light 8 is irradiated from the white fluorescent lamp 4 toward the blade 1, since the blade 1 is held while being inclined as described above, as shown in FIG.
Is the upper surface 1a and the side surface 1 that form the edge portion 3 to be inspected.
It is incident on each of b.

As a result, most of the irradiation light 8a incident on the upper surface 1a of the blade 1 is reflected at an angle of about 10 to 20 ° with respect to the upper surface 1a, so that most of it is reflected and transmitted through the upper surface 1a. The light 9a has a light intensity lower than that of the irradiation light 8a by a reflected light component. Irradiation light 8b incident on one side surface 1b is incident on the side surface 1b at an angle of about 70 to 80 °, and therefore most of it is transmitted, and transmitted light 9b transmitted through side surface 1b is equivalent to irradiation light 8a. It has almost the same light intensity.

Then, the transmitted light 8 transmitted through the blade 1
Is received by the line light receiving sensor 5. Figure 3
The waveform of the sensor signal 10 output from the line light receiving sensor 5 by this light reception is shown.

Here, in the obtained sensor signal 10, the signal portion on the left side in the figure in which the signal level is at a high level is a boundary from the side surface 1b portion of the blade 1 where the signal level changes from a high level to a low level. The signal portion of FIG. 3 indicates a signal level corresponding to the transmitted light (light intensity) from the edge portion 3 and the signal portion on the right side in the figure where the signal level is low.

Thus, the distribution (contrast) of the light intensity between the upper surface 1a and the side surface 1b forming the edge portion 3 can be obtained. Then, a point p where the light intensity is largely switched indicates an edge portion. The vertical change in the signal level in the signal waveforms corresponding to the side surface 1b portion and the upper surface 1a portion of the blade 1 is due to variations in the light transmission characteristics of the respective surfaces.

In the apparatus of this embodiment, the detection processing means 7 inspects a defect in the edge portion 3 based on the information on the light intensity distribution of the transmitted light. That is,
When the edge portion 3 has a defect, the sensor signal portion 10a having a low signal level (light intensity) is obtained from the line light receiving sensor 5 which receives the transmitted light, as shown by the chain double-dashed line in FIG. This is because the edge shape of the defective portion is different from the regular one, and the irradiation light 8 to the defective portion is scattered, and the light transmission characteristic thereof is also different (decreased) from the regular one. Then, since the abnormal signal portion around the edge portion of this light intensity distribution corresponds to the defective portion, the defect of the edge portion is detected by this.

Incidentally, the cleaning blade in this embodiment is usually in the vertical direction (the arrow z direction in FIG. 1) or the front-back direction (the optical axis x direction in FIG. 1) with respect to the mounting reference position of the metal plate bracket 2. ), And the mounting state varies. On the other hand, among the defects in the edge portion, the size of the minimum size defect is about 10 μm.

Therefore, in this embodiment, as shown in FIGS. 1 and 2, as the light receiving optical system 11 of the line light receiving sensor 5, the transmitted light around the edge portion 3 of the blade 1 having a variation in its mounting state is surely performed. It is necessary to use one that can receive light. As the light receiving optical system 11, for example, a magnifying optical system having a magnification of 1 to 2 in a commercially available microscope lens or the like may be used. With such a magnifying optical system, a depth of focus of about 0.5 mm can be obtained. Therefore, even if the blade 1 is mounted in the front-rear direction (optical axis x direction), the peripheral area including the edge portion 3 can be varied. The transmitted light can be reliably received.

Further, in this case, if the line light receiving sensor 5 having, for example, 1000 pixels is used, the field of view of the sensor is about 0.7 to 1.4 mm. However, the transmitted light in the peripheral region including the edge portion 3 can be reliably received.

Next, the detection processing means 7 will be described.
The detection processing means 7 can reliably detect a defect in the edge portion even if the mounting position of the blade 1 varies.

First, in FIG. 4, the blade 1 is moved to sequentially receive light by the line light receiving sensor 5 along the line direction y of the edge portion 3, and the sensor signals from the light receiving sensor 5 at that time are sequentially stored. The surface development image obtained is shown.
That is, in FIG. 4, the vertical direction represents all pixel information of the line light receiving sensor 5, the horizontal direction thereof represents pixel information of the edge portion 3 in the line direction y, and the solid line 12 in the drawing represents the edge portion obtained from the sensor signal. 3 line, dotted line 1
Reference numeral 3 indicates the line position of the regular edge portion when the blade 1 is attached to the reference position.

As shown in FIG. 4, when the mounting of the blade 1 is inclined, the line of the edge portion 3 is also inclined. Therefore, the detection method based on the assumption that the edge portion is at a fixed position may not be able to detect the defect 14 or the like in the edge portion in the inclined state.

The detection processing means 7 in this embodiment can surely detect the defect of the edge portion 3 in such an inclined state. Therefore, as shown in FIG. A line memory 20 for storing (m pixels × n) line signals and an average value calculation circuit 2 for averaging the signal levels of the respective pixels of the stored line signals.
1 and the comparator 22 constitute a main part thereof.

According to the detection processing means 7, first, the sensor signals 23 for m pixels from the line light receiving sensor 5 are stored in the nth row of the line memory 20, and the m pixels from the sensor 5 after the next scanning are stored. Minute line signal level is line memory 2
It is shifted and stored in the (n-1) th row of 0, and thereafter, the line signal levels for a total of n rows are similarly stored. Next, for the m pixels × n line signals 24 recorded in the line memory 20, the average value calculation circuit 21 calculates the average value of the signal level for each pixel, and the average value is calculated for each pixel (1 to m). A reference signal 25 that is digitized is output. Then, in the comparator 22, the reference signal 25
Is compared with the latest sensor signal 23a from the line light receiving sensor 5, and when the sensor signal 23a has an abnormal signal level portion as compared with the reference signal 25, it is identified as a defective portion and, for example, a binary treatment is performed. Defect detection signal 2
By outputting as 6, the defect is inspected.
The dotted line 25a in FIG. 3 shows the signal waveform of the reference signal 25 described above.

In this detection processing means 7, since the line light receiving sensor 5 uses an average value for each pixel of n rows immediately before the latest light receiving scanning position as the reference signal 25, the position of the edge portion is used. Even if the value fluctuates, the detection processing is performed following the fluctuation and the defect inspection is surely executed. For example, the inclination state of the edge portion is 220
When the maximum is 500 μm with respect to mm, the vertical fluctuation range of the edge portion obtained in the sensor signal of the line light receiving sensor 5 is about 0.1 μm or less, and therefore, a minimum edge defect of about 10 μm is detected. , And can be clearly discriminated and detected without being confused with the variation information of the edge position.

From this point of view, even if the position of the edge portion is slightly changed, defect inspection can be carried out without any trouble, and therefore the moving mechanism for moving the blade 1 at the time of inspection must also be a device having highly accurate transfer characteristics. Alternatively, it may be simple and inexpensive.

The number (n) of sensor signals stored in the line memory 20 for producing the reference signal 25 is preferably less than 10 lines, more preferably 2 to 3 lines. If the quantity is n = 10 rows or more, there is a high possibility that the signal data of the defective portion will be included in the average value, which is not preferable as the reference signal.

FIG. 6 shows a defect inspection apparatus according to another embodiment of the present invention. This defect inspection apparatus employs a reflected light method in place of the transmitted light method of the above-described embodiment. As shown in FIG. 7, the line light-receiving sensor 5 in the above-described embodiment uses the reflected light 15 from the cleaning blade 1. For example, the blade 1 is arranged at a position where it can receive light, for example, at a position inclined by 30 ° with respect to the axial direction z perpendicular to the optical axis x, and the edge portion 3 to be inspected faces the sensor 5 side.
It has the same structure as that of the above-mentioned embodiment except that it is arranged at a position inclined by 5 to 10 ° with respect to the axial direction z.

According to this embodiment, as shown in FIG. 7, the irradiation light 8 from the white fluorescent lamp 4 and the upper surface 1a forming the edge portion 3 to be inspected in the blade 1 held in an inclined state. Light is incident on each of the side surfaces 1b. As a result, since the incident angle of the irradiation light 8a on the surface 1a is about 10 to 20 ° with respect to the normal direction on the upper surface 1a, reflection and scattering mainly occur, and a relatively high level reflected light 15a is obtained. On one side surface 1b, the incident angle of the irradiation light 8b on the surface 1b is about 70 to 80 ° with respect to the normal direction, so that the irradiation light is almost transmitted (transmitted light 9b) and is not reflected. The reflected light 15b is obtained, and the reflected light is received by the line light receiving sensor 5. As a result, the sensor signal 16 having a waveform as shown in FIG. 8 is obtained as information of the light intensity distribution.

The sensor signal 16 has a low signal level. The signal portion on the left side of the drawing is the side surface 1b of the blade 1.
The signal portion from the portion serving as a boundary from which the signal level changes from the low level to the high level is transmitted from the edge portion 3, and the signal portion on the right side in the figure where the signal level is at the high level is transmitted from the upper surface 1a portion of the blade 1. The signal levels corresponding to light (light intensity) are shown. Thus, even in the reflected light type inspection apparatus, the upper surface 1 forming the edge portion 3
A light intensity distribution (contrast) between a and the side surface 1b is obtained, and the point p at which the light intensity is largely switched indicates an edge portion.

After this, the defect inspection of the edge portion 3 is performed by the same principle and the detection processing means 7 as in the above-mentioned embodiment.

In each of the embodiments, the cleaning blade is taken as an example of the object to be inspected, but the present invention is not limited to these, and in addition to this, a glass substrate such as an image sensor or an optical such as a cylindrical mirror. It can be applied to the defect inspection of the edge portion in the inspected object such as a component in the unit of μm size. As the light source 4, instead of a white fluorescent lamp, for example, light that guides halogen light from a halogen light source with an optical fiber bundle and irradiates a spot light of about 10 μm around the edge portion 3 using a lens or the like. Irradiation means or the like can be used.

[0037]

As described above, according to the present invention,
The defect can be inspected by a simpler principle, and the defect can be surely detected even if the position of the edge portion to be inspected changes. Further, an apparatus for realizing the defect inspection method has a simple structure, is small in size, and can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a surface defect inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a surface defect inspection method by the apparatus of FIG.

FIG. 3 is a waveform diagram of a sensor signal.

FIG. 4 is an explanatory diagram showing a surface expansion image of a sensor signal.

FIG. 5 is a block diagram showing a configuration example of detection processing means.

FIG. 6 is a perspective view showing a configuration of a surface defect inspection apparatus according to another embodiment of the present invention.

7 is a conceptual diagram showing a surface defect inspection method by the apparatus of FIG.

FIG. 8 is a waveform diagram of a sensor signal.

[Explanation of symbols]

1 ... Object to be inspected, 3 ... Edge portion, 1a, 1b ... Edge portion 3
Adjacent two surfaces forming a light source, 4 ... Light source, 5 ... Line light receiving sensor, 7 ... Detection processing means.

Claims (2)

[Claims] 1. A transparent object to be inspected having a line-shaped edge portion is irradiated with uniform light so that two adjacent surfaces forming an edge portion to be inspected are allowed to enter, and When the transmitted light or reflected light obtained in a range along the direction orthogonal to the line direction of the edge portion is received and the light reception is sequentially performed along the line direction of the edge portion, the intensity distribution of the received transmitted light or reflected light A method for inspecting a surface defect, which comprises detecting a defect on the basis of the information of 1. 2. A light source for irradiating uniform light so as to enter two adjacent surfaces forming an edge portion of the inspection target in a light-transmitting inspection target, and a light source of the light source for irradiating the inspection target A line light receiving sensor that receives transmitted light or reflected light obtained in a range along a direction orthogonal to the line direction of the edge part and sequentially receives the light along the line direction of the edge part, and a transmission received by the line light receiving sensor A surface defect inspection apparatus comprising: a detection processing unit that detects a defect based on a sensor signal indicating an intensity distribution of light or reflected light.