JPH0560513A - Optical line mark detector - Google Patents

Abstract

PURPOSE:To improve line mark detection accuracy by constituting an optical system of a light emitting and receiving optical coaxial body, and making a lens movable in an axial direction and spotlight variable. CONSTITUTION:Light emitted from a light source 4 passes a light emitting optical fiber 13, and is irradiated as a spot to a web 1 by a lens system comprising objective lenses 8 via a fiber bundle 12. Light reflected from the spot returns through the lens system and passes the fiber bundle 12. Furthermore, the reflected light is branched into right and left light receiving fibers 14, and respectively imaged on light receiving elements 11. A line mark deviation on the web 1 is detected from an output difference between the right and left light receiving elements 11. Also, the lenses 8 are moved in an optical axis direction for making spotlight variable and obtaining a spot size corresponding to the breadth of the line mark, thereby improving line mark detection accuracy. In this case, the lens system is inclined by an angle within the range of 3 to 10 degrees with a vertical line to the web 1 in a web travel direction. As a result, regular reflected light and diffused reflected light can be received, and there is no need to change light emitting and receiving optical axes, depending upon the type of the web 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical line mark detector for detecting a line mark printed on a moving web by printing or the like, and particularly to a detection accuracy which is not affected by a change in the width of the line mark. To a detector that can determine

[0002]

2. Description of the Related Art In a slitter machine for cutting a printed web in the direction of the running line of the web (slitting machine), the position of the cutter knife is usually fixed and the roll position for feeding the web to the cutter knife is controlled. An optical line mark detector is used for control. In addition, when the webs are overlapped or when multiple printing is performed, the guide roll or the rewind roll is moved to control the position of the web in the direction perpendicular to the running direction of the web. At this time, the line mark detector is also used. ..

FIG. 11 shows an example of such a slitter.
It is a figure which shows the structure of a machine. The printed web is wound around the unwinding roll, and the web unwound from the unwinding roll has line marks printed at the ends. The line follower head detects whether or not the line mark is in the normal position on the detection roll, and the line mark is sent to the cutter unit and cut by the cutter knife at the ears and the center at both ends in the web running direction and then wound on the winding roll. .. Here, as the line mark, a line included in the printed pattern may be used as the line mark without being specially provided.

The line follower head detects whether or not the line mark is displaced from a predetermined position, and when the displacement is detected, it outputs an unwinding roll position correction signal. This correction signal is amplified by the web guide amplifier and output to the servo guide. The servo guide converts this electric signal into hydraulic pressure, operates the operating cylinder, and corrects the position of the unwinding roll and corrects the deviation of the line mark. Note that control is often performed by an electric actuator without using hydraulic pressure.

FIG. 12 is a diagram showing an optical system of a line follower head. The light emitted from the light source 4 is passed through the filter 5,
The condenser lens 6 brings the light into parallel rays, and the half mirror 7 bends it 90 degrees downward. After that, it is condensed by the objective lens 8 and becomes the spot light 3 to the line mark 2. The reflected light of the line mark 2 passes through the objective lens 8 and the half mirror 7, and forms an image on the light receiving element (Cds cell) surface.

FIG. 13 shows the structure of the light reception detector. (A) shows the light receiving element 11. The light receiving element is composed of two parts 11a and 11b, and when the image of the line mark 2 is formed in the center of the light receiving element 11, the light receiving amounts of both 11a and 11b become equal, but if they deviate from each other, a difference in output occurs. .. (B) shows a circuit for detecting this output difference by a bridge.

[0007]

The detection accuracy of the line mark 2 is affected by the spot width and the thickness of the line mark 2 shown in FIG. If the spot width is too small or too large with respect to the line mark width, the ratio of the change in the detected light amount due to the deviation of the line mark from the spot center to the total detected light amount becomes small. The preferable size of the spot width depends on the width of the line mark itself, but is usually 2 to 3 times the thickness of the line mark. The thickness of the line mark 2 depends on the print content of the web 1 0. Although it is about 5 to 5 mm, it is preferable that it is fine in terms of space and appearance.

On the other hand, when the width of the spot 3 is large, even when the pattern is near the line mark 2, the pattern is also detected. On the other hand, if the line mark 2 is too small, the line mark 2 is likely to deviate from the spot 3 even if the variation is small. When the line mark 2 deviates from the spot 3, the lateral blurring of the line mark 2 cannot be detected. Such a problem is caused by the spot width being set constant.

The light reflected by the surface of the web 1 has two types of components, diffuse reflection and regular reflection. The glossy surface such as aluminum foil has more regular reflection light components. In the case of paper or the like, the diffuse reflection light component increases and the specular reflection light component decreases. For this reason, a glossy aluminum foil or the like cannot be detected if it deviates from the specular reflection light. Therefore, since the specular reflection light is detected, the reflection of the line mark is less than the reflection of the foil portion with the optical axis perpendicular to the web 1. Use this to make a decision. In the case of paper with a lot of diffuse reflection light, use the fact that the optical axis is inclined 50 ° -80 ° with respect to the web 1 and there is little reflection from the paper part with a lot of diffuse reflection and the line mark part near regular reflection Detection. Therefore, it is necessary to change the angle of the optical axis according to the type of the web 1.

Further, as shown in FIG. 12, it is necessary to divide the light projecting axis and the light receiving axis by the half mirror 7, and it is necessary to make the reflected light enter the light receiving elements 11a and 11b evenly. Adjustment was quite difficult.

The present invention has been made in view of the above-mentioned problems, and the spot width is made variable according to the thickness of the line mark to improve the detection function, and also the line mark in which the optical system is simplified. An object is to provide a detection device.

[0012]

In order to achieve the above object, spot light is projected onto a line mark marked in the running direction of the web by an optical system, and the reflected light is received to determine the running direction of the web. In an optical line mark detector for detecting a variation of the line mark in a right angle direction, the optical system is composed of a light emitting and receiving coaxial body having a light emitting axis and a light receiving axis coaxial with each other, and a lens can be moved in the optical axis direction. Then, the size of the spot light is made variable.

Further, the transmitting / receiving coaxial body is tilted in a predetermined angle range in a web traveling direction from a vertical axis with respect to the web surface.

Further, as the optical system, a light source and a light receiving element and a lens system are used to transmit and receive light by using an optical fiber bundle.

Further, the optical fiber bundle is M
The number of the light-transmitting fibers, the N number of the first light-receiving fibers, and the number of the N second light-receiving fibers are the same. 2 The light receiving fibers are arranged symmetrically with respect to the web running direction along one direction, and the light projecting fibers are arranged in parallel by M / 2 by sandwiching the first and second light receiving fibers. In addition, a light receiving element is provided on each of the first light receiving fiber and the second light receiving fiber on the side opposite to the lens system.

The diameters of the first light receiving fiber and the second light receiving fiber are smaller than the diameter of the light projecting fiber.

[0017]

2 is a diagram for explaining the adjustment of the spot width according to the present invention. (A) shows a state in which the light emitted from the light source 4 forms an image of the spot 3 of the width W1 on the web 1 by the objective lens 8. (B) shows a state in which the objective lenses 8 are moved relative to each other and on the optical axis with respect to the light source 4 to set the spot width on the web 1 to W2. As described above, according to the present invention, since the spot width can be adjusted in accordance with the thickness of the line mark 2 by adjusting the lens system, the blur detection accuracy of the line mark 2 can be improved.

FIG. 3 is a diagram for explaining that the size of the image formed on the light receiving element that receives light is constant and invariable even if the spot width is changed according to the present invention. In this figure, the number of target lenses is one, but the principle is the same even when two lenses are used. In other words, the combined focal length of the two lenses should be used.

Referring to FIG. 3 with reference to the reference numerals of FIGS. 1 and 2, in FIG. 3A, an image point is passed through an objective lens 81 composed of an object point (light source 4) with the light projecting axis and the light receiving axis being coaxial. The spot 3 is imaged on the (web 1). Spot 3
The reflected light passes through the same light receiving axis as the light projecting axis and forms an image on the image point of the light receiving element 11 at the same position as the light source 4. (B) shows a case where the combined objective lens 82 is adjusted to change the size of the spot 3 on the web 1.

In this case, the reflected light of the spot 3 on the web 1 passes through the light receiving axis and is located at the same position as the light source 4 in the light receiving element 11.
The image is formed on the upper part (image point), but the size of the image formed on the light receiving element 11 is the same as before moving the combined objective lens 82, that is, in the case of (a). As a result, even if the size of the spot width is adjusted, the size of the image formed by the reflected light of the spot 3 can be made constant, so that the line mark detection accuracy is maintained and the adjustment of the optical system is simplified. ing.

That is, in order to form an image on the same web even if the objective lens combined by d is moved, two lenses are used, the lens interval is changed, and the combined focal length is changed from f1 to f2. The distance between the light source 4 and the distance between the lens and the web 1 can be interlocked and changed to appropriate values to obtain a desired spot size.

FIG. 4 is a view for explaining the inclination between the light emitting / receiving axis and the web 1. (A) is substantially perpendicular to the surface of the web 1 and is suitable for receiving specularly reflected light. (B) is suitable for receiving diffusely reflected light in a state of being inclined at 50 ° to 80 ° with respect to the surface of the web 1. (C) is an inclination angle applied to the present invention, which is inclined within a range of 3 ° to 10 ° from a line perpendicular to the surface of the web 1. This is an inclination angle at which both a part of specular reflection light and a part of diffuse reflection light can be received. By adopting such an inclination angle, it is not necessary to change the light projecting / receiving axis depending on the type of the web 1.

Further, by forming an optical fiber bundle between the lens system and the light source and the light receiving element as an optical system, coaxialization of the optical axis system can be easily achieved, and the flexibility and installation space of the optical fiber are small. As a result, the degree of freedom in arrangement of the device is increased.
Further, the light source and the electric parts can be kept away from the flammable atmosphere caused by the solvent.

Further, the arrangement of the respective fibers of the optical fiber bundle is changed so that the N of the first light receiving fibers is arranged at the joining portion with the lens system in the direction perpendicular to the web traveling direction.
This fiber is placed on the right side and the second light receiving fiber is placed on the left side, and the light receiving fiber rows are sandwiched to arrange the light projecting fibers in parallel in the front-back direction of the web. The reflected light of the spot is easily received by the light receiving fiber, and when the line mark shifts to the right in the web traveling direction, the light receiving amount of the first light receiving fiber increases, and when it shifts to the left, the light receiving amount of the second light receiving fiber. Therefore, the detection accuracy can be improved by reacting sharply to the lateral deviation of the line mark. Since the light projecting fiber is outside the light receiving fiber, the influence of external light on the light receiving fiber can be reduced.

Further, by making the diameters of the first light receiving fiber and the second light receiving fiber smaller than the diameter of the light projecting fiber, the detection characteristic in the direction perpendicular to the web running direction becomes continuous. Further, since both the light emitting and receiving fibers are arranged long in the direction perpendicular to the web running direction and short in the running direction, they are less likely to be affected by the inclination of the light emitting and receiving axis. Even if the total spot area is small,
The deviation detection range of the amount of light received between the light-receiving fiber and the second light-receiving fiber can be made large, and compared to the circular spot,
Even if the amount of light is the same, the range ability becomes large.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. The light from the light source 4 passes through the projecting optical fiber 13 and the objective lens 8 through the optical fiber bundle 12.
The web system 1 is irradiated with a spot by a lens system including Light reflected from the spot returns through the lens system, passes through the optical fiber bundle 12, and receives light from the left and right fibers.
It is divided into 14 and forms an image on the light receiving element 11. The deviation of the line mark on the web 1 is detected from the output difference between the left and right light receiving elements 11. The lens system is mounted at an angle of 3 ° to 10 ° from the perpendicular to the web 1 in the web running direction.

FIG. 5 is a block diagram of the lens system. The lens system includes two objective lenses 8 and each objective lens 8 can be moved in the optical axis direction. The lens system includes a first inner cylinder 16 to which the objective lens 8 is attached and another objective lens 8
Attached second inner cylinder 17, first inner cylinder 16 screwed to the first middle cylinder 18, the first middle cylinder 18 and the outer cylinder connected with the set screw 21
20, the second inner cylinder 17 and the second outer cylinder 20 that are screwed together
The inner cylinder 19, the second middle cylinder 19 and the outer cylinder 20 are integrally constituted by a set screw 22. The first inner cylinder 16 and the second inner cylinder 17 freely slide in the optical axis direction as shown in the AA cross section, but rotate together with each other in the rotation direction. The 16 screw bitches and the screw pitch of the second inner cylinder have a predetermined relationship, and both objective lenses 8 have a fixed relationship and are interlocked with each other. By moving the lenses, the spot size can be changed. Also, the lens adjustment is facilitated by always forming the image of the light source 4 on the web 1. 6 is B
A cross section and a C cross section are shown.

FIG. 7 is a detailed view of the coaxial optical fiber 12. The cross section A shows the arrangement of the light projecting fiber 13 for transmitting the light from the light source 4. Twelve optical fibers are arranged in a bundle. The cross-section B is the light-receiving fiber 14 on the left side with respect to the running direction of the web. The light-receiving fibers 14 having a diameter smaller than that of the light-transmitting fiber 13 are arranged in a line, and the fibers L1, L2, ..., L6 are arranged in order from the right side. Has been done. The C cross section is a light receiving fiber 14 on the right side with respect to the traveling direction of the web 1. The light receiving fibers 14 are arranged in a line, and the fibers R1, R2, ... R6 are arranged in order from the left side. The D cross section is an arrangement in which the projection fibers are integrated together, and the projection fibers are perpendicular to the web running direction.
13 are arranged in three rows with a light receiving fiber 14 sandwiched in front and behind. The light receiving fiber 14 has R1, R2, ..., R6 arranged from the center axis to the right on the right side of the figure with the center axis as a boundary.
L1, L2, ..., L6 are arranged on the left side from the central axis to the left.

In the examples of FIGS. 7, 8 and 9, the light-receiving fibers are connected in one row, but if the number of fibers is increased and the optical fibers are arranged in two staggered rows in order to smooth the output signal. Good. The same applies to the arrangement of the light projecting fibers. Further, since the light receiving element of this embodiment is close to a rectangle,
Although the B section and the C section are lined up in one row, they may be arranged in a circle or a square according to the shape of the light receiving element.

8 to 10 schematically show the reflection images appearing on the line mark and the light-receiving fiber 14, and FIG. 8 shows the case where the line mark passes through the center of the spot, which is L1 of the B section. The reflection image appears symmetrically in the ~ L3 fiber and the R1 ~ R3 fiber in the C section. FIG. 9 shows a case where the line mark passes through the right half of the spot, and a reflection image appears in R1 to R6 of the C section, but not in the B section. Figure 10 shows C with the line mark protruding to the right to some extent.
The reflected image appears only on R4 to R6 of the cross section. The reflected image from the line mark appears as a small amount of light and is shown in black.

As described above, since the reflected image showing the relationship between the spot and the line mark is input to the light receiving fiber 14, it is converted into an electric signal by the light receiving element and the outputs of the left and right light receiving elements are compared. Thus, it is possible to detect the deviation between the spot and the line mark.

[0032]

As is apparent from the above description, according to the present invention, the spot light is made variable by being constituted by the transmitting / receiving coaxial body and by making the lens movable in the optical axis direction. The size of the corresponding spot can be set, and the line mark detection accuracy is improved. In addition, since the specular reflection light and the diffuse reflection light can be received by inclining the projection / reception axis with respect to the vertical line of the web at 3 ° to 10 °, it is necessary to change the projection / reception axis according to the type of the web. There is no. Further, since the projecting and receiving coaxial body is used, optical adjustment is easy.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram illustrating adjustment of spot size by moving a lens.

FIG. 3 is a diagram illustrating that the size of an image formed on a light receiving element does not change even if the size of a spot is changed.

FIG. 4 is a diagram illustrating a relationship between a light projecting axis and a light receiving axis and regular reflection and diffuse reflection.

FIG. 5 is a diagram illustrating a lens adjustment mechanism.

FIG. 6 is a diagram showing each cross section of FIG. 5;

FIG. 7 is a diagram illustrating a configuration of a coaxial optical fiber.

FIG. 8 is a diagram showing a state of a light receiving fiber when a line mark passes through a center of a light projecting / receiving axis.

FIG. 9 is a diagram showing a state of a light receiving fiber when a line mark passes on the right side of a light projecting / receiving axis when viewed in a web traveling direction.

FIG. 10 is a diagram showing a state of a light-receiving fiber when a line mark passes a considerable right side of a light projecting and receiving axis as viewed in a web traveling direction.

FIG. 11 is a configuration diagram of a slitter machine using a line mark detector.

FIG. 12 is a diagram showing an example of an optical system of a conventional line mark detector.

13 is a diagram showing a light receiving element of the line mark detector shown in FIG. 12 and an output detection circuit thereof.

[Explanation of symbols]

 1 Web 2 Line mark 3 Spot 4 Light source 5, 10 Filter 6 Condenser lens 7 Half mirror 8 Objective lens 9 Diffuser 10 Light receiving element 12 Optical fiber bundle 13 Optical fiber for projecting 14 Optical fiber for receiving 16 First inner tube 17 No. 2 Inner Cylinder 18 First Middle Cylinder 19 Second Middle Cylinder 20 Outer Cylinder 21, 22 Set Screw 81, 82 Composite Objective Lens

Claims (5)

[Claims] 1. A spot light is projected by an optical system onto a line mark printed in the running direction of the web, and the reflected light is received to detect the variation of the line mark in the direction perpendicular to the running direction of the web. In the optical line mark detector, the optical system is composed of a light emitting / receiving coaxial body having a light emitting axis and a light receiving axis coaxial with each other, and a lens can be moved in the optical axis direction to change the size of the spot light. An optical line mark detector characterized in that 2. The optical line mark detector according to claim 1, wherein the transmitting / receiving coaxial body is tilted in a predetermined angle range in a web traveling direction from a vertical axis with respect to the web surface. 3. The optical line mark detection according to claim 1, wherein an optical fiber bundle is used between the light source and the light receiving element and the lens system as the optical system to transmit light and receive light. vessel. 4. The optical fiber bundle is composed of M light projecting fibers, N first light receiving fibers, and N second light receiving fibers, and a fiber arrangement is provided at a coupling portion with the lens system. Is arranged such that the first light receiving fiber and the second light receiving fiber are arranged symmetrically with respect to the web traveling direction along one direction.
The light-receiving fiber is sandwiched and the light-transmitting fiber is sandwiched by M
/ 2 lines are arranged in parallel, and light-receiving elements are respectively provided on the side opposite to the lens system of the first light-receiving fiber and the second light-receiving fiber.
Optical line mark detector described. 5. The optical line mark detector according to claim 4, wherein the diameters of the first light receiving fiber and the second light receiving fiber are smaller than the diameter of the light projecting fiber.