JPH0634569A - Appearance deficiency detector for color sheet - Google Patents

Abstract

PURPOSE:To obtain an appearance deficiency detector for a color sheet which enables proper processing corresponding to the cause of the generation of defi ciency by performing a judgment to clarify even the cause of the generation of the deficiency. CONSTITUTION:This apparatus detects deficiency of appearance of a color sheet 40 based on an output of an image pickup section using a CCD line sensor 2 which receives transmission light or reflected light irradiated to the color sheet from a light source 1 and is provided with a differentiation processing section 8 to perform a differentiation processing of an output voltage from the CCD line sensor 2. Moreover, an appearance deficiency detecting section 7 is provided to compare the output voltage from the CCD line sensor 2 with a threshold set previously so that the deficiency of the appearance is detected when the output voltage exceeds the threshold. A appearance deficiency judging section 9 is provided and judges the presence of the deficiency of the appearance based on the output of the appearance deficiency detecting section 7 while judging the type of the deficiency of the appearance by comparing an output of the differentiation processing section 8 with a judging reference value set inside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an appearance defect detection device for detecting appearance defects such as pinholes and foreign substances existing on the surface of a color sheet.

[0002]

2. Description of the Related Art FIG. 6 shows a manufacturing process of a color sheet.

Base roll 31 and comma roll coater 3
2 is provided close to each other, and the process paper 33, which is the base material of the color sheet wound around the base roll 31, passes through the gap between the base roll 31 and the comma roll coater 32, and is in the direction of arrow A in the figure. And is taken up by the take-up roll 36 (see FIG. 5). Further, the base roll 31 is provided with a solvent accommodating portion 35 for accommodating the solvent 34 in a portion around which the process paper 33 is wound, and the comma roll coater 32 is dipped in the solvent 34 in the lower half thereof. Are arranged as follows.

That is, the process paper 33 is the base roll 3
When the surface is immersed in the solvent 34 when orbiting around 1, and is taken up by the take-up roll 36 through the gap between the base roll 31 and the comma roll coater 32, the unnecessary solvent 3
4 is removed, and the solvent 3 having a predetermined thickness is formed on the surface of the process paper 33.
The color sheet 40 coated with No. 4 is manufactured. That is, the coating thickness of the solvent 34 can be adjusted by adjusting the gap between the base roll 31 and the comma roll coater 32.

In the manufacturing process of such a color sheet 40, spot-like defects such as so-called blurring and cissing occur due to various causes.

Blurring is mainly caused by paper powder, dust, etc. adhering to the surface of the base roll 31, and the cross-sectional shape of that portion is as shown in FIG. That is, the thickness of the solvent 34 applied on the process paper 33 is reduced by that portion. Its diameter is about 2 mm.

The cissing is mainly caused by the air in the solvent 34 passing through the gap between the base roll 31 and the comma roll coater 32, and the cross-sectional shape of that portion is as shown in FIG. . That is, the solvent 34 applied on the process paper 33 is lost only in that portion. Its diameter is about 1 mm.

As described above, various kinds of appearance defects as described above occur in the manufacturing process of the color sheet, and therefore, conventionally, there has been provided an apparatus for automatically detecting the appearance defect.

FIG. 5 shows an example of a conventional device for detecting such a defective appearance of a color sheet. This conventional device generally focuses on the difference in transmittance between the good part and the bad part of the color sheet, and the CCD line sensor 12 is provided on the surface of the color sheet.
By taking a picture with
It is detected by the output voltage of the CD line sensor 12. That is, the fact that the output voltage of the CCD line sensor 12 increases when the transmittance is high and the output voltage of the CCD line sensor 12 decreases when the transmittance is low is used.

Here, the output voltage of the CCD line sensor 12 is represented by the product of CCD sensitivity, sensor surface illuminance, and storage time. However, since the reflectance and the transmittance differ depending on the color of the color sheet 40, the illuminance on the sensor surface changes and C
The output voltage of the CD line sensor 12 also changes.

Therefore, in order to eliminate such a problem,
In the conventional apparatus, a method of setting a threshold value in advance according to the color code of the color sheet 40 is generally adopted.

In the figure, in the vicinity of the color sheet 40 pulled from the base roll 31 to the take-up roll 36 side, the process paper 33 side (the lower side of the color sheet 40 in the drawing).
The light source 11 is arranged in the
A CCD line sensor 12 for inputting a surface image of the color sheet 40 is arranged on the opposite side (upper side of the color sheet 40 in the drawing).

The output of the color code input section 19 for inputting a color code is led to a threshold value storage memory 18 for storing a threshold value corresponding to the color code. The output is led to the appearance defect judging section 17 to which the output of the CCD line sensor 12 is led. Also, C
The output of the drive unit 14 is guided to the CD line sensor 12. The drive unit 14 is composed of a clock pulse generation circuit 15 that generates a read pulse (clock pulse) per bit and a start pulse generation circuit 9 that generates a read pulse (start pulse) per line.

That is, in this apparatus, when the color code of the color sheet 40 is input from the color code input section 19, the threshold value corresponding to the color code stored in the threshold value storage memory 18 is read out, and the external appearance is obtained. It is given to the defect determination unit 17. In the appearance defect determination unit 17, the CCD line sensor 12
When the output voltage exceeds the threshold value, it is determined that the external appearance is defective by comparing the output voltage from the threshold voltage and the threshold value read from the threshold value storage memory 18.

[0015]

As described above, in the conventional appearance defect detection device, since the quality determination is performed by focusing only on the difference in the transmittance between the good portion and the defective portion of the color sheet, the cause of the occurrence is Different defects (that is, blurring and cissing) will all be judged as the same defect if they have the same transmittance, and even if a defect is detected, appropriate measures cannot be taken according to the cause of the defect. was there.

The present invention has been made in view of the above circumstances, and an object thereof is to detect an appearance defect of a color sheet by discriminating even the cause of the defect and enabling appropriate treatment according to the cause of the defect. To provide a device.

[0017]

In order to solve the above-mentioned problems, an appearance defect detecting device for a color sheet according to the present invention provides a defect in appearance of the color sheet, which is transmitted light or reflected light of light emitted from a light source to the color sheet. A device for detecting based on the output of an image pickup unit using a CCD line sensor for receiving light, the differential processing unit for differentially processing the output voltage from the CCD line sensor, the output voltage from the CCD line sensor, and the internal The appearance defect detection unit that detects the appearance defect when the output voltage exceeds the threshold value and the presence or absence of the appearance defect based on the output of the appearance defect detection unit are compared. In addition to the determination, an appearance defect determination unit that determines the type of the appearance defect by comparing the output of the differentiation processing unit and the determination reference value set inside is provided.

[0018]

The image signal of the color sheet input by the CCD line sensor is converted into a voltage value and sent to the appearance defect detection section and the differentiation processing section.

In the appearance defect detection unit, the output voltage from the CCD line sensor is preset inside by utilizing the difference in the transmittance (difference in brightness) between the non-defective part and the defective part of the color sheet. When the threshold value is exceeded for a certain period of time or more, it is determined that the appearance is defective, and a detection signal of the appearance defect is output to the appearance defect determining unit.

On the other hand, in the differential processing section, the signal from the CCD line sensor is passed through a delay circuit to perform differential processing, and the differential processed signal is output to the appearance defect determination section.

The appearance defect judging section first judges the presence or absence of the appearance defect based on the detection signal from the appearance defect detecting section, and calculates the position thereof. Next, from the signal from the differentiation processing unit,
The maximum differential value of the defective portion is extracted, and if the maximum differential value exceeds the internally set judgment reference value, the cause of the defective appearance is cissing. It is determined that the cause of occurrence of blur is blur.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the electrical construction of a color sheet appearance defect detecting apparatus according to the present invention.

In the figure, in the vicinity of the color sheet 40 pulled from the base roll 31 to the take-up roll 36 side, the process paper 31 side (the lower side of the color sheet 40 in the drawing).
The light source 1 is disposed on the color sheet 40, and the color sheet 40 is provided on the side opposite to the light source 1 via the color sheet 40 (on the upper side of the color sheet 40 in the drawing).
A CCD line sensor 2 for inputting the surface image of is arranged.

The CCD line sensor 2 includes a drive unit 4
The output of the CCD line sensor 2
Output is led to the appearance defect detection section 7 and the differential processing section 8. Further, the output of the appearance defect detection unit 7 and the differentiation processing unit 8
Is output to the appearance defect determination unit 9.

The drive unit 4 is composed of a clock pulse generation circuit 5 for generating a read pulse (clock pulse) per bit and a start pulse generation circuit 6 for generating a read pulse (start pulse) per line. Therefore, the output of the starting operation unit 10 that starts the detection operation of the present apparatus is guided to the start pulse generating circuit 6.

The appearance defect detection section 7 compares the output voltage from the CCD line sensor 2 with a preset threshold value, and when the output voltage exceeds the threshold value for a certain period of time or longer, This is to detect a defective appearance.
Further, the differentiating unit 8 differentiates the output voltage from the CCD line sensor 2.

The appearance defect judging section 9 judges the presence or absence of an appearance defect based on the detection signal from the appearance defect detecting section 7, and calculates the position thereof. In addition, from the signal from the differential processing unit 8,
The maximum differential value of the defective portion is extracted, and the cause of the appearance defect is determined by whether or not the maximum differential value exceeds the internally determined determination reference value.

In this embodiment, the light source 1 uses a direct current fluorescent lamp and the CCD line sensor 2 uses two 2048-bit fluorescent lamps, and the resolution is 0.33 mm. Further, the irradiation method adopts the transmission method, the line speed of the color sheet 40 is 15 m / min, and the sheet width is 1300 mm.

Next, the operation of the appearance defect detection device having the above configuration will be described.

First, the manufacturing of the color sheet 40 is started by the manufacturing process shown in FIG.

At this time, the back surface of the color sheet 40 (process paper 3
Light is radiated from a DC straight tube fluorescent lamp from the 3 side). Then, the light transmitted through the color sheet 40 is received by the CCD line sensor 2. The image signal of the color sheet 40 input by the CCD line sensor 2 is converted into a voltage value and sent to the appearance defect detection unit 7 and the differentiation processing unit 8.

In the appearance defect detecting section 7, as shown in FIG. 2, the output voltage B from the CCD line sensor 2 is compared with a threshold value T preset inside, and the output voltage B is compared.
When the value exceeds the threshold value T for a certain period of time S or more, it is determined that the appearance is defective, and a detection signal of the appearance defect is output to the appearance defect determination unit 9.

Here, the constant time S is set so that when the output voltage level exceeds the threshold value T for a moment due to noise or the like generated in the circuit, it is determined that the appearance is not defective. This is to prevent erroneous determination. Further, in this embodiment, the threshold value T is 0.15 as an offset to the base level B1 of the output voltage B.
The value obtained by adding B1 is used.

On the other hand, in the differential processing section 8, as shown in FIG. 3, the signal from the CCD line sensor 2 is differentially processed,
The result is output to the appearance defect determination unit 9.

The appearance defect determining section 9 first determines the presence or absence of an appearance defect based on the detection signal from the appearance defect detecting section 7, and calculates the position thereof. Next, the maximum differential value of the portion determined to be defective is extracted from the signal from the differential processing unit 8, and it is determined whether or not the maximum differential value exceeds the internally determined determination reference value L. To do.

As shown in FIG. 4, CC at the blurred portion
The level of the output voltage of the D line sensor 2 becomes lower than the level of the output voltage of the CCD line sensor 2 in the cissing portion. Therefore, as for the signal waveforms obtained by differentiating these output voltage waveforms by the differentiating unit 8, as shown in FIG. 7B, the signal waveforms of the portions corresponding to blurring are more than the signal waveforms of the portions corresponding to cissing. The waveform has a low level (small differential value).

In consideration of this point, the judgment reference value L is set to a value higher than the maximum differential value of the portion corresponding to blurring and lower than the maximum differential value of the portion corresponding to cissing.

As a result, if the maximum differential value of the portion determined to be defective exceeds the determination reference value L, the cause of appearance defect is cissing, and if it does not exceed the reference value L, blurring is the cause of appearance defect. Can be determined.

Based on such a discrimination result, the worker
It is possible to take appropriate measures according to the cause of the defect. It is also possible to calculate the defect occurrence rate per unit area of the color sheet 40 to determine the quality of the product.

In the above embodiment, the constant time S is
Although it is explained as a constant time regardless of the cause of blurring or cissing, a fixed time S1 corresponding to the blurring is set for the blurring, and a constant time S2 (S1> S2) corresponding to the blurring is set for the blurring. ) Can be set.
In this case, by the time S0 during which the output voltage from the CCD line sensor 2 exceeds the threshold value T, S1>S0> S2
If so, the cause of the appearance defect is cissing, and S0> S
If the value is 1, it is possible to determine that the cause of the appearance defect is blurring.

[0042]

The apparatus for detecting the appearance defect of a color sheet according to the present invention has a differentiating section for differentiating the output voltage from the CCD line sensor, the output voltage from the CCD line sensor, and a preset threshold value inside. A visual defect detection unit that compares the value with an output voltage to detect a visual defect when the output voltage exceeds a threshold value, and determines the presence or absence of a visual defect based on the output of the visual defect detection unit. Since the configuration is provided with an appearance defect determination unit that determines the type of appearance defect by comparing the output of the unit and the determination reference value set inside, it is possible to determine even the cause of the defect. Appropriate measures can be swiftly taken according to the cause of occurrence. Further, this brings about an effect that a large number of defects can be prevented in advance.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of an appearance defect detection device for a color sheet according to the present invention.

FIG. 2 is a graph showing a relationship between an output voltage of a CCD line sensor and a threshold value when a defective appearance portion is detected.

FIG. 3 is a waveform diagram of a signal differentially processed by a differential processing unit.

FIG. 4 is a waveform diagram for explaining a determination process in an appearance defect determination unit.

FIG. 5 is a block diagram showing an electrical configuration of a conventional appearance defect detection device.

FIG. 6 is a schematic view showing a manufacturing process of a color sheet.

FIG. 7 is a sectional view showing a portion where blurring occurs.

FIG. 8 is a cross-sectional view showing a portion where cissing occurs.

[Explanation of symbols]

 1 Light Source 2 CCD Line Sensor 4 Driving Section 7 Appearance Defect Detection Section 8 Differentiation Processing Section 9 Appearance Defect Judgment Section 40 Color Sheet

Claims (1)

[Claims] 1. An apparatus for detecting an appearance defect of a color sheet based on an output of an image pickup unit using a CCD line sensor for receiving transmitted light or reflected light of light emitted from a light source to the color sheet, wherein: When the output voltage from the CCD line sensor is differentiated and the output voltage from the CCD line sensor is compared with an internal preset threshold value, the output voltage exceeds the threshold value. An appearance defect detection unit that detects an appearance defect and whether or not there is an appearance defect is determined based on the output of this appearance defect detection unit, and the output of the differentiation processing unit is compared with the determination reference value set inside. An appearance defect detection device for a color sheet, comprising: an appearance defect determination unit that determines the type of appearance defect.