JPS6211153A - Sensor head for detecting printing flaw - Google Patents

Abstract

PURPOSE:To perform photometry with a constant characteristic by continuous and constant quantity of light, by respectively forming a light-emitting optical fiber and a light-receiving optical fiber in a laminar form so as to closely contacting the same and laminating both fibers. CONSTITUTION:Light-emitting optical fiber layers TT are formed in a long laminar form in the lateral direction at a right angle to the flow direction of a sheet by respectively closely adhering light-emitting optical fibers 14A-14D and light-receiving optical fiber layers JR, JG, JB are formed by arranging light- receiving optical fibers 11, 12, 13 in a laminar form. When the interval between a sensor head 1 and printed matter 9 is set to 1mm, the green (G) light receiving region JJG of the green (G) optical fiber layer JG is preset in the light emitting regions TTG of both adjacent optical fiber layers TT contacted with both sides of said light-receiving optical fiber layer to enable photometry.

Description

[Detailed Description of the Invention] (Technical Field of the Invention) This invention uses optical fibers to illuminate and measure the printing surface, and to improve the ink intensity when printing on packaging materials such as paper, aluminum, and plastic snacks. The present invention relates to a sensor head for detecting printing defects, which detects printing defects such as scattering, doctor's lines, and adhesion of dust by color photometry.

(Technical background of the invention and its problems) In general, it is difficult to detect defects that appear in spots during high-speed printing, so it is difficult to detect defects that appear in spots during high-speed printing. Only visual inspections have been conducted. However, since it was not possible to inspect all the products, problems often occurred as defective products could get mixed in inside. Therefore, high-speed defect detection systems that can be used during operation have recently emerged.

Figures 4 (A) and (B) show an example of such a printing defect detection device, which receives visible light and separates it into red (R), green (G), and blue (B). , a color sensor element 60A that generates a corresponding output voltage.

Two sets of sensor heads 6A and 6B are used, each consisting of a plurality of BOB light-receiving surfaces arranged in a horizontal row.

One of the heads 8A, 8B is placed in the width direction perpendicular to the wave direction of the sheet before winding up of the printed matter 9 on which the patterns 9A, 9B, ... are continuously printed, and the other of the detection units is placed in the width direction of the sheet Shift the printing pitch of the above pattern by one or several pitches in the flow direction.

The color sensor elements 80A and 80B are arranged so as to correspond to each other in the sheet flow direction, and the reflected light from the printed matter is received by two sets of sensor heads SA and 8B, and the corresponding colors between the two sets of sensor heads are detected. The controller 8 calculates the differential voltage for red (R), green (G), and blue (B) of the sensor element, and detects defects in printed matter by comparing this differential voltage with a preset voltage. It was designed to do so.

When converting the content of a printed matter into an electrical signal and detecting printing defects, in principle, a photo sensor such as an amorphous optical sensor is used as the color sensor element of this sensor head, facing the printed matter. The shading of the printed surface can be converted into electrical signals, which can be used to detect printing defects. In practice, when reading printed matter with high resolution, it is not only structurally unreasonable to install many photosensors near the printed matter, but also due to the external dimensions of the photosensors.

Since the resolution is limited, recently the sensor head uses optical fibers such as glass fibers to transport the amount of light detected from the printed matter to a place separated by a distance, and then connects the end of the optical fiber at that distant place. A method of reading printed matter has been realized by connecting a photosensor to the part. In this case, a common method is to place the light-receiving optical fiber of the sensor head facing the printing surface, and direct the reflected light obtained by shining light from a light source onto the printing surface through this light-receiving optical fiber. , the light-receiving optical fiber itself casts a shadow, making it difficult to maintain a constant luminous intensity on the printed matter. Therefore, measures such as separating the light-receiving optical fiber from the printing surface are sometimes used, but this results in problems such as deterioration of resolution. Optical fiber Jl and multiple optical fibers for light emission↑
1 to 8, and a plurality of light emitting optical fibers are arranged regularly around the light receiving optical fiber to surround the light emitting and receiving part 100. be. However, when multiple light-receiving optical fibers are required, such as in the case of color photometry, the number of optical fibers increases, making it difficult to downsize due to the structure, and furthermore, it leads to increased costs. be.

Therefore, the present applicant has provided an optical fiber light projecting/receiving device (Japanese Patent Application No. 59-288109) which corrects the above-mentioned drawbacks and can be configured with a minimum number of optical fibers. As shown in FIG. 6(^), the sensor head 6 of this light emitting/receiving device using an optical fiber is arranged to surround one light receiving optical fiber and the light receiving fiber so as to be in close contact with each other regularly. 6 optical fibers T with the same diameter for light projection
A plurality of sets of 111 light emitting/receiving optical fibers 100 consisting of The optical fibers 101 are arranged regularly so that some optical fibers are left and others are omitted. In this sensor head 6, light is transmitted to the printed matter 9 by the light emitting optical fiber T.
, and this reflected light is connected to the receiving optical fibers R1 to RN.
, GINGN and 81-ON. Figure (B) shows the relationship between the light emitting area and the light receiving area.
The light projecting area TTI formed on the printed matter 9 by irradiation by the six optical fibers 1 to T8 of the above-mentioned light projecting optical fibers and the light receiving optical fiber J! which receives these reflected lights! There is a light receiving area JJI. Here, the light-receiving area JJI on the printed material and the light-receiving area shared by all the other light-receiving optical fibers exist within the light-emitting area created by irradiating the printed material 9 from all the light-emitting optical fibers T. It has become.

Now, regarding the same figure (C) showing the EE-EE cross-sectional view,
If the distance rJD between the light emitting optical fiber IQI and the printed matter 9 and the diameter of one optical fiber are approximately equal, the light emitting area of one light emitting optical fiber will have a diameter that is approximately twice the diameter of the optical fiber. It is known to span a range. Similarly, regarding the light-receiving region, it is known that the light-receiving optical fiber can detect the amount of light in a diameter range that is about twice or more the diameter of the optical fiber. Here, in No. 61iU(A), the light receiving optical fiber Jl is placed in the center, and the light receiving optical fibers are placed around it next to a set of light emitting and receiving optical fibers consisting of six light emitting optical fibers Tl-TO. Looking at the light emitting optical fibers of the L group of light emitting and receiving optical fibers centered around J2, the above-mentioned light emitting optical fiber 〒2 is for the light receiving optical fiber Jl, and the light receiving optical fiber 2 is for the light receiving optical fiber. It is also used as In other words, it is sufficient to have at least one light emitting optical fiber between two sets of light emitting and receiving optical fibers adjacent to each other, and the light emitting areas TTI, TT2. TT3... is not irradiated independently for each of the light receiving areas JJI, JJ2..., but is omitted so that they can be used together.

However, when using a sensor head made of this light emitting/receiving optical fiber 101, FIG. 7(A).

As shown in (B), the optical fiber for light reception is old, G1°81
, R2, 02, and B2, the optical IQ of the reflected light from the printed matter is as shown in the same figure (B). Since it is not constant over the entire printed surface, it is not possible to detect defects on the entire printed surface, and using the method described above that detects printing defects by comparing the amount of light received by two sets of sensor heads causes errors and cannot be accurately detected. The drawback is that defects cannot be detected.

In addition, one light receiving optical fiber and the light receiving fiber are connected to B.
#! This sensor unit has a large number of optical fibers, including six optical fibers for transmitting light and one set of optical fibers for transmitting and receiving light, which are arranged in close contact with each other regularly. However, forming the light emitting optical fiber and the light receiving optical fiber separately is very complicated and difficult to manufacture.

(Object of the invention) This invention was made under the above circumstances,
An object of the present invention is to provide a sensor head composed of a plurality of light-receiving optical fibers used for color photometry to detect printing defects, and to generate a constant amount of light by a continuous constant amount of light in the width direction perpendicular to the running direction of the printed material. It is an object of the present invention to provide a sensor head for detecting printing defects that can perform photometry based on characteristics and can be easily manufactured.

(Summary of the Invention) The present invention relates to a sensor head for detecting printing defects that detects defects in printed matter by performing color photometry. A fiber layer, and a plurality of sets of light-receiving optical fiber layers formed in layers using a plurality of glass fibers and alternately arranged adjacent to each of the light-emitting optical fiber layers, The laminated functional light-receiving parts are integrated.

(Embodiment of the Invention) FIG. 1 shows an embodiment of the sensor head 1 of the present invention, and as shown in the end face view of FIG. , for example, projection optical fibers 14A, 14B, 1 made of glass fibers with a diameter of 5 x 1.
The optical fiber layers JR, JG, and J8 are each made of glass fibers with the same diameter. Light receiving optical fiber 11,
12.13 as above and IIl! ! 7851L1
It is formed in m layers, and these laminated functional light receiving parts are formed so as to be integrated. The length of the sensor head 1 in the width direction perpendicular to the sheet flow direction is arbitrarily determined according to the dimensions of the printed material. Now, in the same figure (B) showing the AA-AA cross-sectional view,
When the distance LL between the sensor head l and the printed matter 9 is set to about 11 mm, the green (G) light receiving optical fiber layer J is shown in Fig. 1.
The G light-receiving area JJa of ε is the light-emitting area TTG of the adjacent light-emitting optical fiber layers it that are in contact with both sides of this light-receiving optical fiber layer.
It can be seen that photometry can be performed because the light exists within the .

Similarly, the light receiving optical fiber layer JR for each other color (R, B)
, J8 are also arranged to exist within the light emitting areas of the light emitting optical fiber layers TT adjacent to each other on both sides, so that photometry is possible.

As shown in FIG. 3(A), the sensor head l having such a configuration is shown in the BB-BB cross-sectional view of FIG. As shown, the end face on the printed surface side is formed, and the longitudinal direction is arranged in the width direction perpendicular to the sheet flow direction, and the terminal end of the light emitting optical fiber layer TT of this sensor head is
A pair of sensor heads are bundled together into a light condensing section 16.
is formed. This light condensing section 18 is located at CC in FIG.
- As shown in the CC cross-sectional view, the light emitting optical fibers are bundled in a circular shape so that they are in close contact with each other, and the ends that correspond to the light converging surfaces are arranged so that the end surfaces of each optical fiber form a uniform plane. It has become.

A halogen lamp 17, which is a light emitting source, is provided opposite the end face of the light condensing section 16 via a heat ray shielding plate 18, and only the light beams whose heat rays are blocked by the heat ray shielding plate 18 are transmitted to the light condensing section 1B. The light enters from the end face of the sensor head and is irradiated onto a printed matter (not shown) by the light emitting optical fiber of each sensor head. Here, in this invention, since glass fiber is used for each fiber, it has good heat resistance, and the halogen lamp 17, which is a powerful light source, can be used, and a sufficient amount of light can be sent to the printing surface. This means that even minute printing defects can be accurately identified.

On the other hand, each color of the above two sets of sensor spatulas v IA and IB (
R, G, B) The terminal ends of the light-receiving optical fiber layers JR, JG, and J8 are divided into measurement areas for each color.
Two sets of sensor heads are combined into multiple sets for one minute.
A plurality of paired color sensor elements 10 are connected to each color (R, G, B) light receiving element 10A, 10B, IOc arranged in a horizontal line in each measurement area, and this light receiving optical fiber layer JR, JG, The optical signals of each color received by the pair of color sensor elements 10A, 108,
A controller (not shown) calculates the differential voltage between the two sets of light receiving elements for each color, and by comparing this differential voltage with a preset voltage, printing defects can be detected. Here, since the light-receiving optical fiber is formed so as to be in close contact in the width direction perpendicular to the flow direction of the sheet, as shown in FIGS. 2(A) and (B), the photometry of this light-receiving optical fiber layer is The characteristics are for each color (R, G
, B), it is possible to continuously and uniformly measure the amount of light Q in the width direction perpendicular to the flow direction of the sheet, and print defects can be detected continuously and uniformly over the entire printed surface of the printed material according to the flow of the sheet. Become.

(Modified example of the invention) In the above embodiment, each color (R, G, B) is arranged in an example, but the order of this embodiment is free, and the same effect can be obtained by arranging the colors in any order. can be raised.

It goes without saying that the method can also be applied to monochrome.

(Effects of the Invention) As described above, according to the present invention, the sensor head l can be easily manufactured by forming the light-emitting optical fiber and the light-receiving optical fiber in layers so as to be in close contact with each other and laminating them. In addition, since the light-receiving optical fibers are formed in close contact with each other in a layered manner, it is possible to measure light with constant characteristics using a continuous constant amount of light in the width direction perpendicular to the sheet flow direction on the printing surface. It is possible to provide a printing defect detection sensor head that can accurately detect defects, is easy to manufacture, and has good performance.

[Brief explanation of the drawing]

,! FIG. 1(A)-(temple) is a diagram showing an embodiment of this invention;
Figure 2 (A) and (+1) are diagrams explaining this invention, Figure 3.
Figures (A) to (C) are diagrams showing one application example of this invention.
Figures (A) and (B) are diagrams explaining the printing defect detection device, Figures 5, 6 (A) to (C), and Figures 7 (A) and (B).
FIG. 2 is a diagram showing a conventional sensor head. DESCRIPTION OF SYMBOLS 1...Sensor head, 9...Printed material, 1O...Bare type color sensor element, 11, 12.13... Optical fiber for light reception, 14A, 14B, 140, 140...
・Optical fiber for light projection, 17...Halogen lamp, 18
...Heat ray shielding board. Applicant's agent Yu Yasugata 2 Zugo 4 Figure (B)

Claims (1)

[Claims] In a printing defect detection sensor head that detects defects in printed matter by performing color photometry, there are multiple sets of light emitting fiber layers formed in layers using multiple glass fibers, and layered fiber layers using multiple glass fibers. and a plurality of sets of light-receiving optical fiber layers alternately arranged adjacent to each of the light-emitting fiber layers, so as to integrate the laminated light-emitting and receiving parts. A sensor head for detecting printing defects, characterized by: