JP2001311693A - Inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection apparatus by which the good image of even an object to be inspected, having a comparatively low reflectance of light is acquired and by which the object to be inspected can be inspected precisely. SOLUTION: In order to inspect the surface of the developing roller 100 of a laser printer, a light source 1, a camera 2 and a personal computer 21 which performs an image processing operation on the basis of image data from the camera 2 are provided. Since the camera 2 is equipped with a TDI-type CCD sensor, the good image of a low-reflectance product such as the developing roller 100 can be acquired, and the product can be inspected precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for illuminating an inspection object and photographing an image of the inspection object to inspect the surface of the inspection object, and more particularly to an inspection object having a low light reflectance. The present invention relates to a suitable inspection device.

[0002]

2. Description of the Related Art Various inspection apparatuses have been proposed for inspecting the surface of a product.

For example, Japanese Patent Laying-Open No. 11-183391 proposes an inspection apparatus for inspecting a cylindrical object such as a photosensitive drum of a printer.

This inspection apparatus includes a light source for irradiating an inspection object such as a photosensitive drum with light, a line sensor for receiving reflected light from the inspection object, and a surface sensor for inspection based on an output signal from the line sensor. An image processor that processes images and detects defects such as dirt and scratches on the surface of the inspection object, and inspects the entire surface of the inspection object by sequentially rotating the inspection object It is.

[0005] In addition, this inspection apparatus has an object to be inspected corresponding to the performance of the line sensor in view of the fact that the accuracy of detecting a defect depends on the relative moving speed between the line sensor and the inspection object. It is characterized in that the number of rotations of the object is set.

Here, in the case where a product whose surface is made of a metal, amorphous, or the like, such as a mirror surface, such as a photosensitive drum, is to be inspected, the surface of the product is not affected by a light source. Since the light is sufficiently reflected, it is possible to obtain a sufficient amount of light required for image processing in the line sensor.

For this reason, Japanese Patent Application Laid-Open No.
Setting the number of revolutions of the inspection object in accordance with the performance of the line sensor as described in Japanese Patent Publication No. 91 is necessary when inspecting a product having a surface with a high light reflectance such as a photosensitive drum. Is also considered valid.

[0008]

However, when inspecting a product having a low surface light reflectance, the quantity of light is often insufficient to obtain an image. For example, products whose surfaces are covered with rubber, resin, etc., such as developing rollers and fixing rollers, which are components of laser printers, have a low light reflectance, and the relative movement speed between the sensor and the inspection object is low. Regardless, it is difficult to obtain an image required for inspection.

Accordingly, an object of the present invention is to provide an inspection apparatus capable of acquiring a good image of an inspection object having a relatively low light reflectance and thereby performing an accurate inspection. is there.

[0010]

According to the present invention, there is provided an inspection apparatus for inspecting a surface of an inspection object, wherein a light source for illuminating the surface of the inspection object and an image of the surface of the inspection object are taken. And a photographing means for generating the image data, wherein the photographing means includes a TDI type CCD sensor.

According to this means, the photographing means is a TDI
Since the type CCD sensor is included, a good image can be obtained even if the reflectance of light on the surface of the inspection object is low, and an accurate inspection can be performed.

Examples of the inspection object having a low light reflectance include, for example, a developing roller, a fixing roller, a charging roller, a transfer roller, a belt-shaped product, and a product for development used in an image forming apparatus such as a laser printer. , Etc.
According to the present invention, relatively accurate inspection is possible.

Further, according to the present invention, there is provided a determining means for determining the quality of the surface of the inspection object based on the image data, wherein the determining means determines that the brightness value of the image data is a predetermined upper limit value. May be determined based on whether or not exceeds a predetermined lower limit. This allows humans not to be present
The inspection can be performed automatically.

In this case, the image data is distinguished by using the upper limit value or the lower limit value as a threshold value, or a value in a range between the upper limit value and the lower limit value and a value in another range. By doing so, means for binarizing can be provided. Thereby, the inspection result can be easily identified.

The determining means may determine whether a range continuously exceeding the upper limit value or a range continuously falling below the lower limit value is larger than a predetermined range. The quality can also be determined.

The determining means may determine whether the value exceeds the upper limit or the value exceeds the lower limit.
The type of defect can also be determined. Defects present on the surface of the inspection object focus on the fact that the brightness varies depending on the type.

Further, in the present invention, there may be provided a display means for displaying an image of the inspection object based on the image data. This allows the inspector to visually identify the presence or absence of the defect.

In the present invention, the angle between the photographing direction of the photographing means and the irradiation direction of the light source is 30.
Preferably, it is any angle between degrees and 135 degrees.

In the present invention, the object to be inspected may have a cylindrical shape or a cylindrical shape. In this case, a support means for supporting the object to be inspected rotatably around its central axis is provided. And a drive unit for rotating the inspection object around its central axis. This is a purpose corresponding to the shape of the inspection object.

In this case, moving means for moving the support unit may be provided to relatively move the inspection object and the photographing means. Further, a moving means for moving the photographing means may be provided in order to relatively move the inspection object and the photographing means. This is because when the entire inspection object is not included in the imaging range of the imaging unit, the inspection object is partially and sequentially imaged.

Further, in the present invention, the light source may irradiate slit light along a central axis direction of the inspection object. This is to reduce illumination unevenness.

Further, the light source is preferably a metal halide lamp.

Further, according to the present invention, there is provided an inspection apparatus for inspecting the surface of an inspection object, comprising: a light source for illuminating the surface of the inspection object; an image of the surface of the inspection object; An imaging device for generating data, wherein the illuminance of the light source is in a range of 500,000 to 3,000,000 lux.

Further, according to the present invention, there is provided an inspection apparatus for inspecting the surface of an inspection object, wherein a light source for illuminating the surface of the inspection object, an image of the surface of the inspection object, and an image thereof are taken. And a photographing means for generating data, wherein the light source is constituted by a metal halide lamp.

[0025]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a front view showing a configuration of a mechanical system of an inspection apparatus A according to an embodiment of the present invention, and FIG. 2 is a right side view thereof.

The inspection apparatus A is an apparatus for inspecting the surface of the developing roller 100 used in the laser printer, and illuminates the surface of the developing roller 100 with a light source 1 and photographs the surface of the developing roller 100. A camera 2 for capturing image data. Further, the inspection device A includes a support unit 3 for supporting the developing roller 100.

This inspection apparatus A is capable of removing dents such as pinholes and scratches on the surface of the developing roller 100, dust, lint, adhesion of foreign matter such as metal and dissimilar materials, stains, dirt, or surface coating. Inspection for defects such as dimensional errors such as wrinkles and distortions.

The light source 1 is composed of, for example, a laser light emitting device, a metal halide lamp, a halogen lamp, or the like. When inspecting a device having a low reflectance, such as the developing roller 100, about 500,000 to 3,000,000 lux. A suitable inspection can be performed as long as the illuminance can be obtained. As a lamp capable of obtaining the illuminance in such a range, a metal halide lamp can be exemplified.

The metal halide lamp generally refers to a discharge lamp in which a plurality of metal halides, for example, sodium, thallium, indium, skadium, etc., are sealed in an arc tube of a high-pressure mercury lamp. Although light is emitted, in this embodiment, it is particularly desirable to employ a metal that emits light that is colorless or nearly colorless.

The light source 1 is mounted on a holder 11, and the holder 11 is provided with a guide rail 1 installed substantially horizontally.
0 supported. Further, the guide rail 10 is supported by a guide rail 9 provided substantially vertically. The guide rail 10 can move up and down along the guide rail 9, and can be fixed at an appropriate position. Thereby, the height of the light source 1 can be adjusted.

The holder 11 can be moved back and forth along the guide rail 10 with respect to the developing roller 100, and can be fixed at an appropriate position. Thereby, the position of the light source 1 in the front-back direction can be adjusted.

Further, the light source 1 includes a pin 11 a of the holder 11.
It can be supported so as to be rotatable around, whereby the direction of illumination can be adjusted. FIG. 3 illustrates several irradiation directions of the light source 1, and among them, particularly, when the reflectance is low like the developing roller 100, the camera 2 is used.
It is preferable that the angle between the shooting direction of the light source and the irradiation direction of the light source 1 is any angle in the range of 30 ° to 135 °, and it is particularly preferable that the angle is any angle in the range of 90 ° to 120 °. It has been confirmed by experiments that a proper inspection can be performed.

It is preferable that the light source 1 emits slit light along the central axis of the developing roller 100 rather than spot light. This is because the imaging region of the developing roller 100 can be more uniformly illuminated.

The camera 2 is supported on a guide rail 12.
Can be moved back and forth with respect to.

The camera 2 includes an optical system element such as a condenser lens,
It is composed of a CCD sensor and the like, and it is also possible to use a polarizing filter as needed.

The camera 2 is, in particular, a TDI type CCD.
A sensor (also referred to as a multi-stage CCD sensor) is used. As shown in FIG. 4, the TDI-type CCD sensor has a plurality of line sensor elements arranged not only in a horizontal line but also in a multi-stage manner in a vertical direction.
It outputs the result of adding vertical lines.

In such a TDI type CCD sensor, 1
Even in an environment where the light receiving sensitivity is higher than in the case of the line configuration and the amount of light is small, a good image can be obtained, and even if the inspection target such as the developing roller 100 having a small reflectance is sufficient, Inspection becomes possible.

Here, the number of stages of the line sensor can be determined as appropriate, but it is particularly desirable to use any one of the stages in the range of 4 to 96 stages. If the number of stages of the sensor is four or more, it is possible to obtain an image that can withstand practical use even with a product having a low light reflectance such as the developing roller 100. However, if the number of stages of the sensor is simply increased, This is because the image tends to be blurred when the number of stages of the sensor is increased, and when the number of stages exceeds 96, the image quality required for the surface inspection as in the present embodiment may not be obtained.

Here, a metal halide lamp or a halogen lamp is used as a light source, and a camera using a TDI-type CCD sensor and a camera using a normal (single-type) CCD sensor are combined with each other to generate light on the surface of the developing roller. A description will be given of the result of a comparison experiment of the detection rate when inspecting a defect.

In the comparative experiment, a defect of 0.2 mm or less, which is difficult to judge in the in-house sensory test, in which pinholes, scratches, adhesion of metal, adhesion of foreign material, adhesion of lint, and projections are attached in advance. Using the developed developing roller, the detection rate of these defects was measured in each combination.

The presence or absence of a defect is determined by comparing the image taken by the camera with 2
The value was converted to a value, the processed image was displayed on a display, and it was visually determined whether or not a defect appeared on the image.

The illuminances of the metal halide lamp and the halogen lamp were 2.5 million lux and 500,000 lux, respectively (measured at a position 15 mm from the light emitting end). TDI type CC
The number of stages of the D sensor was 96 stages. The other experimental environments were similar in each case.

FIG. 9 shows the results of the comparative experiment.

Comparing the case where a metal halide lamp is used as the light source with the case where a halogen lamp is used, it is clear that the defect detection rate is higher when the metal halide lamp is used. From this result, it was confirmed that the inspection accuracy (accuracy of the captured image) differs depending on the illuminance of the light source in the inspection target having a low surface light reflectance.
In this comparative experiment, the metal halide lamp emits almost colorless light. However, it is added that this point also seems to affect the inspection accuracy. That is, it is considered that not only the illuminance is simply high but also the colorless emission color has higher inspection accuracy.

Further, comparing the case where the TDI type is used as the CCD sensor and the case where the single type is used as the CCD sensor,
The defect detection rate is higher when the DI type is used.
It can be seen that the drop is large when a halogen lamp is used.

It should be noted that first, the TDI type CCD
In the case of a combination of a sensor and a metal halide lamp, an extremely high detection rate is obtained, and these combinations are considered to be the best combination.

Second, when a metal halide lamp is used, an extremely high detection rate is obtained for defects other than protrusions even with a single CCD sensor,
Regardless of the type of D sensor, it can be confirmed that the use of a metal halide lamp as a light source is extremely effective.

Third, even when a halogen lamp is used as a light source, a detection rate of at least 70% is obtained when a TDI type CCD sensor is used.
A detection rate that can withstand practical use has been obtained. From this,
In particular, it can be confirmed that the TDI CCD sensor is effective for an inspection object having a low surface light reflectance, regardless of the nature of the light source.

Next, returning to FIG. 1 and FIG.
Will be further described.

The support unit 3 basically has a pair of supports 31 and 32 for rotatably supporting the developing roller 100 around its central axis, and a motor 33 for rotating the developing roller 100 around its central axis. And.

The support 31 and the support 32 have shaft portions 31a and 32a which are inserted into the developing roller 100 concentrically with the center axis of the developing roller 100 and support the same.

The support 31 has a bearing 31b for rotatably supporting the shaft 31a, and a table 31c on which the bearing 31b is mounted.

The support member 32 includes a bearing portion 32b for rotatably supporting the shaft portion 32a, and a rotational force of the motor 33 for the shaft portion 3.
A table 32c on which a bearing 32b and a motor 33 are mounted;
Having.

The tables 31c and 32c are both mounted on a guide rail 4 extending in the direction of the center axis of the supported developing roller 100, and along the guide rail 4, in the left-right direction of FIG. You can move. The auxiliary rails 8 are arranged on the side surfaces of the tables 31c and 32c, and assist the movement of the tables 31c and 32c.

The table 32c of the support 32 has a motor 5 for moving the support 32 along the guide rail 4. The motor 5 rotationally drives a pinion 6 arranged below the table 32c as shown in FIG. 2, and the pinion 6 is connected to a rack 7 provided on the side surface of the guide rail 4 along the longitudinal direction thereof. When the pinion 6 is rotationally driven by the motor 5,
The support 32 automatically moves along the guide rail 4. As the support 32 moves, the developing roller 10
Since the support member 31 also moves via the reference numeral 0, the entire support unit 3 can move along the guide rail 4 by the rotational drive of the motor 5.

Next, the configuration of the electric system of the inspection apparatus A will be described with reference to FIG.

The inspection apparatus A includes a personal computer 21 connected to the camera 2 and a camera power supply 22 for supplying power to the camera 2.
And a power supply 23 for supplying power to the light source 1 and a mechanical system control unit 2 for controlling the configuration of mechanical systems such as the motors 5 and 33.
4 and an operation panel 25 for an inspector to give a control command to the mechanical system control unit 24.

The personal computer 21 controls the camera 2 and
The image data obtained by the photographing is processed, and based on the image data, judgment of an inspection result, display of an image, and the like are performed.

The mechanical control section 24 controls the rotation of the developing roller 100 by the motor 33 and controls the positioning of the support unit 3 by the motor 5. Motor 33
And 5 can be performed by a rotary encoder or the like attached thereto, and the positioning control of the support unit 3 is performed by a position detection sensor or the like appropriately provided on the guide rail 4 in the longitudinal direction thereof. You may.

The mechanical control section 24 may be configured as an independent circuit, or may be functionally implemented on the personal computer 21.

Next, the operation of the inspection apparatus A will be described.

In the inspection apparatus A, first, the developing roller 100
Is supported by the support members 31 and 32. Next, the arrangement of the light source 1 and the camera 2 is appropriately adjusted, and the operation unit 25 controls the support unit 3 by the motor 5 so that the shooting area of the camera 2 covers the area on one end side of the developing roller 100.
Perform positioning. This is because the photographing range of the camera 2 is limited, and the photographing area is sequentially moved from one end of the developing roller 100 to the other end. FIG. 1 shows a developing roller 100.
2 shows an aspect in which the positioning is performed so that the area on one end side of the is covered.

Further, the rotation of the motor 33 is controlled by the operation panel 25, and the developing roller 100 is rotated at a constant speed via the coupling 32d and the shaft portion 32a.

With the rotation of the developing roller 100, the personal computer 21 starts photographing with the camera 2, and the developing roller 100
The image of the surface of is taken into the personal computer 21. At this time, it is needless to say that the personal computer 21 may display an image photographed in real time on its display.

When the camera 2 captures an image of at least one rotation of the developing roller 100, the motor 5 is operated by the operation panel 25 to move the image relative to the camera 2 to capture another area of the developing roller 100. To move the support unit 3 to the right side in FIG.

Then, the developing roller 1 is again operated by the camera 2.
00 is photographed, and this is repeated until the entire area of the developing roller 100 is photographed.

Thus, the taking of the image on the developing roller 100 by the inspection apparatus A is completed. In the above embodiment, in the above embodiment, the movement of the developing roller 100,
The stop is repeated, and the camera 2 shoots the image at the time of the stop. However, it goes without saying that the image may be shot by the camera 2 without stopping while moving the developing roller 100. In the above embodiment, the camera 2 is fixed, and the developing roller 100 is moved, so that the developing roller 1 is moved.
Although the entire area of the surface of the image No. 00 is photographed, it goes without saying that the apparatus may be configured so that the developing roller 100 is fixed and the camera 2 is moved.

Thereafter, the inspector observes the image of the surface of the developing roller 100 displayed on the display of the personal computer 21 to determine whether or not there is any defect on the surface of the developing roller 100, and the inspection is completed. Will be.

In this case, in the inspection apparatus A, in particular, by performing image processing according to the following procedure, the inspection by the inspector can be facilitated or the inspection apparatus A can perform the automatic inspection.

First, the personal computer 21 creates shading data for performing shading correction on the image data from the camera 2. Light source 1 is included in the image data.
This is because errors such as uneven illuminance and distortion of the optical system of the camera 2 are included.

The shading data can be created by averaging the image data of several lines from the camera 2.

FIG. 6A is a diagram showing the created shading data. The vertical axis represents the image data value (luminance value: 256 gradations), and the horizontal axis corresponds to the sensor pixel (sensor pixel position). ) Are shown.

Next, the corrected shading data is created by subtracting the created shading data from the image data from the camera 2. FIG. 6B is a diagram showing image data before correction, and FIG. 6C is a diagram showing data obtained by correcting the image data of FIG. 6B with the shading data of FIG. It is. Note that the data may be shifted in accordance with the shading correction so that the average value of the image data indicates a substantially intermediate value of the gradation.

Here, the image data is stored in the developing roller 100
Fluctuates with a constant amplitude depending on the surface properties, noise, etc. of the surface, but in particular, when there is a defect, the luminance value is significantly higher or lower.

Therefore, an upper limit value and a lower limit value of the luminance value are set, and if there is image data leaking between the upper limit value and the lower limit value, it is determined that there is a defect.

FIG. 7 shows the details of the image data after shading correction. The image data fluctuates with a constant amplitude as a whole, but exceeds the upper limit (white defective portion) and the lower limit. (Black defect)
Exists.

The white defect indicates a brighter area on the surface of the developing roller 100 than other areas. In such a region, for example, defects such as liquid jumping and peeling can be considered. Further, the black defect portion indicates an area on the surface of the developing roller 100 that is darker than other areas. In such a region, for example, defects such as adhesion of foreign matter and flaws can be considered.

As described above, by setting whether or not the luminance value of the image data is in the range between the upper limit value and the lower limit value, the defect can be detected by the personal computer 21 without the inspector observing the image. Automatic determination becomes possible. In addition, the type of defect can be determined based on whether the value exceeds the upper limit or the value falls below the lower limit.

The upper limit value and the lower limit value can be set in advance by a preliminary experiment.
It can also be set based on the mutual comparison of each image data of a plurality of 0 areas. Further, the luminance value of the pixel data of a plurality of continuous predetermined pixels is not based on whether or not the luminance value of the pixel data of one pixel is in the range between the upper limit value and the lower limit value. May be used as a reference.
This takes into account disturbances to the image data.

In order to allow the inspector to visually and clearly identify the presence or absence of a defect, the image data is binarized using the above-described upper limit or lower limit and the personal computer 21
It is also possible to display on a display.

FIG. 8 shows an example of the display.
FIG. 8A is a display example in which a range exceeding the lower limit is set to white using the lower limit as a threshold and binarized, and FIG. 8B is a binarized display in which the range exceeding the upper limit is set to white using the upper limit as a threshold. Display example shown below. FIG. 8C shows a binarized display example in which a range between the upper limit value and the lower limit value is distinguished from a range exceeding the upper limit value and a range exceeding the lower limit value. A point 81 indicates that the luminance value was lower than the lower limit value, and a point 82 indicates that the luminance value was higher than the upper limit value.

By binarizing and displaying the image data in this manner, the presence or absence of a defect can be visually clarified.

[0084]

As described above, according to the present invention,
Even if the inspection target has a relatively low light reflectance, it is possible to obtain a good image of the inspection object and thereby perform an accurate inspection.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of a mechanical system of an inspection apparatus A according to an embodiment of the present invention.

FIG. 2 is a right side view showing a configuration of a mechanical system of the inspection apparatus A.

FIG. 3 is a diagram showing an example of an irradiation direction of a light source 1;

FIG. 4 is a view schematically showing a configuration of a TDI type CCD sensor.

FIG. 5 is a block diagram showing a configuration of an electric system of the inspection apparatus A.

FIG. 6A is a diagram showing shading data. (B) is a diagram showing image data before correction.
(C) is a diagram showing image data after correction.

FIG. 7 is a diagram showing details of image data after correction.

FIGS. 8A to 8C are diagrams illustrating display examples in which image data is binarized and displayed.

FIG. 9 is a table showing a difference in defect detection rate based on a type of a light source and a type of a CCD sensor.

Claims (14)

[Claims] 1. An inspection apparatus for inspecting the surface of an inspection object, comprising: a light source for illuminating the surface of the inspection object; and an imaging unit for imaging the surface of the inspection object and generating image data of the image. An inspection apparatus, comprising: a photographing unit that includes a TDI-type CCD sensor. And a determining unit for determining whether the surface of the inspection object is good or not based on the image data, wherein the determining unit determines that a luminance value of the image data exceeds a predetermined upper limit value, or The inspection apparatus according to claim 1, wherein the quality is determined based on whether or not a value is below a predetermined lower limit. 3. The image data is distinguished by using the upper limit or the lower limit as a threshold, or a value in a range between the upper limit and the lower limit, and a value in a range other than the upper limit and the lower limit. 3. The inspection apparatus according to claim 2, further comprising a binarizing unit. 4. The determination means, based on whether a range continuously exceeding the upper limit or a range continuously falling below the lower limit is larger than a predetermined range, 3. The inspection apparatus according to claim 2, wherein the quality is determined. 5. The inspection apparatus according to claim 2, wherein the determination unit determines the type of the defect based on whether the value exceeds the upper limit or the value exceeds the lower limit. 6. The inspection apparatus according to claim 1, further comprising display means for displaying an image of the inspection object based on the image data. 7. The apparatus according to claim 1, wherein an angle between a photographing direction of the photographing means and an irradiation direction of the light source is any angle between 30 degrees and 135 degrees. Inspection equipment. 8. The inspection object has a cylindrical shape or a columnar shape, a supporting means for supporting the inspection object rotatably around its central axis, and the inspection object around its central axis. The inspection apparatus according to claim 1, further comprising: a support unit for the inspection object having a driving unit that rotates the inspection object. 9. The inspection apparatus according to claim 8, further comprising a moving unit that moves the support unit to relatively move the inspection object and the photographing unit. 10. The inspection apparatus according to claim 8, further comprising a moving unit that moves the photographing unit in order to relatively move the inspection object and the photographing unit. 11. The inspection apparatus according to claim 8, wherein the light source irradiates a slit light along a center axis direction of the inspection object. 12. The inspection apparatus according to claim 1, wherein the light source is constituted by a metal halide lamp. 13. An inspection apparatus for inspecting the surface of an inspection object, comprising: a light source for illuminating the surface of the inspection object; and imaging means for imaging the surface of the inspection object and generating image data thereof. An illuminance of the light source is in a range of 500,000 lux to 3,000,000 lux. 14. An inspection apparatus for inspecting the surface of an inspection object, comprising: a light source for illuminating the surface of the inspection object; and imaging means for imaging the surface of the inspection object and generating image data thereof. Wherein the light source comprises a metal halide lamp.