JPH11288512A - Defect detector for magnetic record medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a single sensor for detection to simultaneously detect a tape surface defect and a tape coating film breakage generated on the surface of the magnetic layer side of a magnetic recording medium. SOLUTION: The subject detector is provided with a detecting guide roll 5a provided with light transmissivity and allowing a magnetic tape 2 to travel on an outer peripheral surface by supporting its nonmagnetic layer side, a light emitting element 6a arranged on the side of the outer peripheral surface on which the tape 2 of the roll 5a travels to irradiate a detecting light L1 onto the magnetic layer of the tape 2, a light source disposed to face oppositely to the side of the outer peripheral surface on which the tape 2 of the roll 5a travels and transmits the roll 5a to irradiate a detecting light L2 onto the magnetic layer of the magnetic record medium, and the sensor for detecting 6 with a light emitting element 6b receiving the light L1 arranged on the side of the outer peripheral surface, on which the magnetic record medium of the roll 5a travels, and reflected by the magnetic layer of the tape 2 and the light L2 transmitting the roll 5a and irradiated onto the magnetic layer of the tape 2 to transmit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect detecting apparatus for a magnetic recording medium, and more particularly, to a magnetic recording medium for simultaneously detecting a surface defect generated on the surface of a magnetic layer and an internal defect generated inside the magnetic layer. And a defect detection device.

[0002]

2. Description of the Related Art A magnetic recording medium such as an audio tape or a video tape is formed by applying a magnetic paint in which a magnetic powder, additives, a solvent and the like are mixed on a base film to form a magnetic layer. In the magnetic recording medium, defects such as irregularities such as imprints and wrinkles formed on the surface of the formed magnetic layer and irregularities due to adhesion of foreign matter (hereinafter, such defects are referred to as tape surface defects) ), And defects due to coating loss of the magnetic paint such as uneven coating of the magnetic paint and pinholes (hereinafter, such defects are referred to as tape coating film defects). When the above-described defects occur in the magnetic recording medium,
This causes a loss of a recording signal, and causes deterioration of image quality and sound quality. For this reason, the magnetic recording medium is inspected for tape surface defects and tape coating film defects during the manufacturing process. These inspections are appropriately performed in the step of cutting the web or a predetermined width.

As shown in FIG. 5, a conventional defect detection device 20 guides a magnetic recording medium 21 fed from a supply unit (not shown) by a plurality of guide rolls 22 and a nip roll 23 to a take-up roll (not shown). It is arranged in a running guide device for winding. The defect detection device 20 includes a first detection unit 24 that detects a tape surface defect, and a second detection unit 25 that detects a tape coating film defect. Each of the plurality of guide rolls 22 is formed in a column shape on which an alumite treatment is performed on the outer periphery and light is not transmitted. Each of the guide rolls 22 is used to drive the magnetic recording medium 2 before or after cutting.
1. The traveling guide is performed by changing the traveling angle of 1.

[0004] The first detector 24 is composed of a light emitting element 26 and a light receiving element 27 housed in an integral case. The first detection unit 24 receives the detection light reflected from the magnetic recording medium 21 emitted from the light emitting element 26 and receives the detection light.
To receive light. The first detector 24 includes a light receiving element 27
Magnetic recording medium 21 based on the amount of detection light received by
The surface defects of the tape generated in the magnetic layer are detected.

[0005] The second detecting section 25 is composed of a light emitting element 28 and a light receiving element 29 which are arranged opposite to each other with the magnetic recording medium 21 running and guided by the guide roll 22 interposed therebetween. The second detection unit 25 outputs the detection light emitted from the light emitting element 28 and transmitted through the magnetic recording medium 21 to the light receiving element 2.
9 to receive light. The second detection unit 25 detects a tape coating film defect occurring in the magnetic layer of the magnetic recording medium 21 based on the amount of detection light received by the light receiving element.

That is, if the surface of the magnetic recording medium 21 to which the detection light is irradiated from the light emitting element 26 of the first detection section 24 has a tape surface defect, it is formed by an abnormal shape or a foreign substance attached to the surface. Due to the unevenness, a part of the detection light is scattered and the amount of the detection light received by the light receiving element 27 decreases. Therefore, when the first detection unit 24 detects a state in which the amount of reflected light from the magnetic recording medium 21 received by the light receiving element 27 is attenuated, a tape surface defect has occurred on the surface of the magnetic recording medium 21. Detect that.

Further, the magnetic recording medium 21 has a light emitting element 28 of the second detecting section 25 in a portion where a tape coating film defect occurs.
Is irradiated, a part of the detection light is transmitted without being blocked by the magnetic recording medium 21 due to uneven coating or a pinhole. Therefore, the second detector 25 is provided with the light receiving element 29
Detects the presence of a tape coating defect on the magnetic recording medium 21 when the detection light from the light emitting element 28 is detected.

The detection of the tape surface defect is performed by using the magnetic recording medium 2.
Since the tape surface defects are extruded and appear as surface irregularities when 1 runs while being supported by the guide rolls 22, it is optimally performed at a portion corresponding to the guide rolls 22. Further, the detection of the tape surface defect is preferably performed in a place as close as possible to the nip roll 23 where the magnetic recording medium 21 runs stably and the flapping of the magnetic recording medium 21 is suppressed so as not to lower the detection sensitivity. For this reason, the first defect detection unit 24 is disposed closest to the nip roll 23 and near the guide roll 22a capable of detecting the surface of the magnetic recording medium 21 on the magnetic layer side.

The detection of the tape coating film defect is performed by a second detecting unit 2.
It is necessary that there is no block between the light emitting element 28 of No. 5 and the magnetic recording medium 21 to block the detection light emitted from the light emitting element 28. For this reason, it is an absolute condition that the second defect detection unit 25 is disposed near the magnetic recording medium 21 running between the guide rolls 22.

[0010]

As described above, the conventional defect detecting apparatus 10 includes a first detecting unit 24 for detecting a tape surface defect occurring on the magnetic recording medium 11, and a first detecting unit 24 for detecting a tape coating film defect. The two detectors 25 are arranged at optimal positions of the tape traveling device. In the conventional defect detection apparatus 10, the two detection units are independently provided as described above, and a data processing apparatus that detects and outputs detected data is also required. For this reason, the defect detection device 1
No. 0 has a problem that a large space is required in the tape traveling device and the cost is high.

Further, the conventional defect detection apparatus 10 detects the defects of the two types of magnetic recording media 11 as described above by separate detection units, so that the detection results used in the defect inspection are different data. They were output on separate papers. For this reason, the conventional defect detection device 10
In the inspection of defects, processing of data output from the first detection unit 24 and the processing of data output from the second detection unit 25 is troublesome, and there is also a problem that a large amount of paper is used for outputting data. Was.

Accordingly, the present invention provides a defect of a magnetic recording medium that enables simultaneous detection of a tape surface defect and a tape coating defect occurring on the surface of the magnetic recording medium on the magnetic layer side by a single detecting means. It is provided for the purpose of providing a detection device.

[0013]

According to the present invention, there is provided an apparatus for detecting a defect of a magnetic recording medium according to the present invention, which has a light transmitting property, and has an outer peripheral surface supporting a magnetic recording medium on a non-magnetic layer side. And a first light source which is disposed on the outer peripheral surface side of the guide roll on which the magnetic recording medium travels and irradiates the magnetic layer of the magnetic recording medium with detection light, and the magnetic recording medium of the guide roll travels A second light source that is disposed to face the outer peripheral surface side and transmits detection light to the magnetic layer of the magnetic recording medium through the guide roll, and is disposed on the outer peripheral surface side of the guide roll where the magnetic recording medium travels; The first detection light from the first light source irradiated by the magnetic layer of the magnetic recording medium and the second detection light from the second light source transmitted through the guide roll and reflected by the magnetic layer of the magnetic recording medium and transmitted. Optical detection sensor that receives the detection light Configured with the door.

According to the defect detecting apparatus for a magnetic recording medium according to the present invention, the guide roll has a property of transmitting light and does not block light emitted from the light source to the magnetic recording medium. Thus, by detecting the reflected light and the transmitted light and comparing them with the reference light amount, it is possible to simultaneously detect the tape surface defect and the tape coating film defect. Further, according to the defect detecting device for a magnetic recording medium according to the present invention, two types of magnetic recording medium defects, a tape surface defect and a tape coating film defect, are detected by one detection sensor. The data is output on one sheet.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of a defect detecting device for a magnetic recording medium according to the present invention will be described in detail with reference to the drawings. A defect detection device 1 for a magnetic recording medium according to the present embodiment is a magnetic tape 2 that is a tape-shaped magnetic recording medium such as an audio tape or a video tape.
In the manufacturing process, as shown in FIG. 1, a cutting machine 3 for cutting a wide magnetic tape into a large number of magnetic tapes 2 having a predetermined width, and a winding machine 4 for winding each of the cut magnetic tapes 2 It is constituted as what is installed between. The magnetic tape 2 is guided to travel by a plurality of guide rolls 5.

As shown in FIG. 2, the defect detecting device 1 corresponds to a detection guide roll 5a which is one of a number of guide rolls 5 for running and guiding the magnetic tape 2 running in the direction of arrow A in the figure. The detection sensor 6 is provided and configured. The defect detection device 1 simultaneously detects the presence or absence of a tape surface defect and a tape coating film defect generated on the magnetic tape 2 running on the outer periphery of the detection guide roll 5 by the detection sensor 6.

The detection guide roll 5a is formed in a cylindrical shape, and a plurality of magnetic tapes 2 cut on the outer peripheral surface run around the detection guide roll 5a. The detection guide roll 5a is formed of a material having mechanical properties such as workability and abrasion resistance and having a light transmittance of 70% or more.
The detection guide roll 5a is configured as a glass guide roll formed of, for example, quartz glass. As shown in FIG. 3, when the detection light from the light source 7 is irradiated, the detection guide roll 3 condenses the light on a condensing surface 9 on the outer peripheral surface facing the incident surface 8 of the detection light. And functions as a cylindrical lens having

If the diameter of the detection guide roll 5a is too small, the curvature of the detection surface to be detected by the detection sensor 6 becomes large, which affects the detection sensitivity. On the other hand, if the diameter of the detection guide roll 5a is too large, the weight of the detection guide roll 5a itself becomes heavy, making it difficult for the detection guide roll 5a to rotate and complicating the structure of the bearing and the like.
For this reason, the guide roll 3 has a diameter of 80 mm to 1 mm.
The one formed to have a size of about 00 mm is preferable.

The detection guide roll 5a is preferably disposed at a position close to the nip roll 10, as shown in FIG. The detection guide roll 5a is a nip roll 10
If the magnetic tape 2 is disposed near the magnetic tape 2, the traveling of the magnetic tape 2 traveling on the outer peripheral surface is stable, so that the detection sensitivity is prevented from lowering due to the flapping of the traveling of the magnetic tape 2.

The detection sensor 6 includes a detection guide roll 5a.
Is a non-contact type optical sensor disposed at a certain distance from the magnetic tape 2 traveling by multiplying by a distance, and detecting the presence or absence of a defect occurring in the magnetic tape 2 due to a change in the amount of light received on the sensor surface. Perform detection. A plurality of detection sensors 6 are arranged in parallel corresponding to the plurality of magnetic tapes 2 running on the detection guide roll 5a.

As shown in FIG. 4, the detection sensor 6 includes a light emitting element 6a for irradiating the detection surface of the magnetic tape 2 with light and a light receiving element 6b for receiving the light reflected on the magnetic tape 2. It is configured. As shown in FIG. 3, the detection sensor 6 has a light-collecting surface 9 on which detection light from a light source 7 disposed at a position opposed to the detection guide roll 5a is condensed.
It is disposed at a position facing the. The detection sensor 6 includes a light-emitting element 6 a whose light-receiving element 6 b is reflected by the magnetic tape 2.
7 reflected by the light source and the light source 7 transmitted through the detection guide roll 5a
The transmitted light from is received.

As shown in FIG. 4, the defect detecting device 1 includes a magnetic tape 2 running on an outer peripheral surface of a detection guide roll 5a.
From the light emitting element 6a of the detection sensor 6
And the light source 7 also emits the detection light L2 toward the magnetic tape 2. When no tape surface defect or tape coating defect occurs, the magnetic tape 2 reflects all the detection light L1 emitted by the light emitting element 6a of the detection sensor 6 to the light receiving element 6b and detects the light emitted by the light source 7. Block all light L2. Therefore, the defect detection device 1
If no defect occurs in the magnetic tape 2, the light receiving element 6
The amount of light received by b is the detection light L1 emitted by the light emitting element 6a.
It is detected that it is the same amount as.

The defect detecting apparatus 1 uses the light amount detected as described above as a reference value and compares the light amount serving as the reference value with the light amounts of the detection light L1 and the detection light L2 received by the light receiving element 6b. To detect a defect occurring in the magnetic tape 2.

That is, when a tape surface defect occurs in the magnetic tape 2, a part of the detection light L1 emitted from the light emitting element 6a is diffused by the unevenness formed on the surface.
For this reason, the defect detection device 1 detects a state in which, when a tape surface defect occurs in the magnetic tape 2, the amount of light received by the light receiving element 6b attenuates below a reference value.

Further, when the tape coating film is defective, the magnetic tape 2 transmits the detection light L2 emitted from the light source 7 due to the coating loss of the magnetic paint. For this reason, the defect detection device 1 detects a state in which the amount of light received by the light receiving element 6b is larger than the reference value when the tape coating of the magnetic tape 2 is defective.

Therefore, the defect detecting device 1 is in a state where the light quantity received by the light receiving element 6b irradiated with the detection light L1 from the light receiving element 6a and the detection light L2 from the light source 7 is attenuated as compared with the reference value. Is detected, it is detected that a tape surface defect has occurred in the magnetic tape 2, and when the increase state is detected, it is detected that a tape coating film defect has occurred in the magnetic tape 2.

Note that the defect detecting device 1 can detect the detection light beams L1 and L1 received by the light receiving element 6b even when the magnetic tape 2 has both a tape surface defect and a tape coating defect.
The defect can be detected by comparing the light amount of No. 2 with the reference value.

In the present embodiment, the defect detection device 1
Has been described as a glass guide roll formed of quartz glass, but this is not intended to limit the material of the detection guide roll 5a. The detection guide roll 5a is formed of a material having light transmittance, and the formed guide roll has a light transmittance of 70%.
% Or more, for example, the detection guide roll 5a may be formed of reinforced plastic or the like.

In this embodiment, the diameter of the detection guide roll 5a is 80 mm to 100 mm.
It was stated that a size of about mm is preferable, but this is because the weight of the guide roll and the convenience in manufacturing when the detection guide roll is configured as a glass guide roll as in this embodiment are considered. . Therefore, the size of the detection guide roll 5a is determined by the material, the weight, and the like, and is not limited to the above-described numerical value of the diameter.

[0030]

According to the defect detecting device for a magnetic recording medium according to the present invention, the detection of the tape surface defect and the tape coating film defect can be performed by one detection sensor, so that the device can be installed in a narrow space. In addition, costs can be reduced. Further, according to the defect detection apparatus for a magnetic recording medium according to the present invention, since two types of defect detection are performed by one sensor, data of the detection result of the defect detection is output on one sheet of paper, and the defect inspection is performed. And the amount of paper used can be reduced by half.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a defect detection device for a magnetic recording medium.

FIG. 2 is a partially enlarged perspective view of the defect detection device.

FIG. 3 is an enlarged view of a main part for describing a light collecting action of a guide roll.

FIG. 4 is an enlarged view of a main part for describing detection light received by a detection sensor.

FIG. 5 is a configuration diagram of a conventional defect detection device for a magnetic recording medium.

[Explanation of symbols]

1 defect detection device, 2 magnetic tape (magnetic recording medium),
5a detection guide roll, 6 detection sensor (optical detection sensor), 6a light emitting element (first light source), 6b light receiving element, 7 light source (second light source)

Claims (2)

[Claims] 1. A guide roll having a light transmitting property and allowing a magnetic recording medium to run on an outer peripheral surface while supporting a non-magnetic layer thereof, and a guide roll disposed on the outer peripheral surface side of the guide roll on which the magnetic recording medium runs A first light source that irradiates the magnetic layer of the magnetic recording medium with detection light; and a first light source that is disposed so as to face an outer peripheral surface side of the guide roll on which the magnetic recording medium travels. A second light source that irradiates the magnetic layer of the magnetic recording medium with detection light; and a first light source that is disposed on the outer peripheral surface side of the guide roll where the magnetic recording medium runs and is reflected by the magnetic layer of the magnetic recording medium. An optical detection sensor that receives first detection light from the light source and second detection light from the second light source that passes through the guide roll and irradiates and transmits the magnetic layer of the magnetic recording medium. And the above optical The detection sensor detects a surface defect of a magnetic layer of the magnetic recording medium by the first detection light,
A defect detecting device for a magnetic recording medium, wherein a defect of a coating film on a magnetic layer of the magnetic recording medium is detected by the second detection light. 2. The guide roll has a light transmittance of 70.
2. The defect detection device for a magnetic recording medium according to claim 1, wherein the defect detection device is formed of a material having a light transmittance of at least%.