JP2002203387A - Magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of dielectric breakdown of a MR head in a magnetic recording and reproducing device provided with the MR head. SOLUTION: A panel main body 9a and an opening and closing cover 9e constituting a front panel 9 is made conductive so that electric resistance values are 0 to 1×1012 Ω, and they are connected electrically to a mechanical chassis. The mechanical chassis is made to have a ground potential, therefore, when a cassette case charged with static electricity is inserted from an opening part 9d, the cassette case is brought into contact with the panel main part 9a and the opening and closing cover 9e in the opening part 9d, thereby, static electricity is discharged to ground through the front panel 9, after that, when a magnetic tape is loaded and comes in contact with a magnetic head for reproduction, occurrence of dielectric breakdown of a MR element is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording / reproducing apparatus for recording and reproducing signals on and from a magnetic tape, and more particularly to a magnetic recording / reproducing apparatus using a magnetoresistive head as a reproducing magnetic head.

[0002]

2. Description of the Related Art In recent years, in a magnetic recording / reproducing apparatus for recording and reproducing data using a magnetic tape, it is desired to further improve the recording density with an increase in the amount of information to be handled. As a magnetic head,
Instead of the conventional inductive head, MR (Magneto Re
It is essential to use a sistive (magnetoresistive effect) head. An MR head is a magnetic head that reads a signal recorded on a magnetic recording medium using a magnetoresistance effect by an MR element, and has a high signal detection sensitivity.
Since a large reproduction output can be obtained, the recording track width on the magnetic tape can be easily reduced, the recording density in the linear direction can be increased, and high-density recording and reproduction can be performed.

As a recording / reproducing device using a magnetic tape, a helical scan for recording and reproducing signals by helically winding a magnetic tape around a head drum device which rotates together with a magnetic head provided on the outer periphery is known. The scheme is known. In this helical scan type recording / reproducing apparatus, the magnetic head slides on the running magnetic tape at a high speed to record and reproduce signals, so that the relative sliding speed between the magnetic tape and the magnetic head is high. An improvement in the data transfer rate has been realized.

[0004]

However, in general, MR
The head has a property that it is susceptible to static electricity and heat as compared with an inductive head. Here, FIG.
ESD (Electrostatic Discharge) in R head
4 shows the results of measuring the breakdown voltage. FIG. 3A shows the AMR (Anis
(otropic Magneto Resistive) head, (b) GMR
(Giant Magneto Resistive) The measurement result about a head is each shown.

[0005] In the measurement values shown in FIG. 3, an HBM (Human Body Model) is used in the measurement of the ESD breakdown voltage.
This shows the relationship between the voltage applied to the device and the resistance when discharging is performed with a resistance value of Ω. According to this, ES
D breakdown voltage is 230-240V for AMR head
And in the case of a GMR head, about 30 to 40 V. On the other hand, the charging voltage of an insulating object (plastic, nylon, vinyl, etc.) under a normal environment easily reaches several kV or more due to friction, contact, induction, etc. Exceed.

A conventional cassette case for winding and storing a magnetic tape is often formed of a high-resistance synthetic resin material. Such a cassette case is easily rubbed with, for example, artificial fiber packing material or gloves in the process of handling by a user, or rubbed with parts during loading on a magnetic recording / reproducing apparatus. Charges static electricity. The charging voltage of the synthetic resin material used for the cassette case is, for example, 1500 to 2000 V or more for an ABS resin having a surface resistance of about 10 ¹⁶ Ω / sq, and the half-life is 3 minutes or more. Since the value of this charging voltage is much higher than the withstand voltage of the MR head, and the half-life is long, the charging once generated does not readily attenuate. For this reason, when the cassette case charged with static electricity is inserted into the magnetic recording / reproducing apparatus and a chance occurs that the magnetic tape comes into contact with the MR head, a large amount of current flows through the MR head via the magnetic tape, and the MR head becomes static. There is a risk of electrical breakdown.

FIG. 4 conceptually shows a flow of charges when the magnetic tape and the MR head come into contact with each other. The drum device 40 provided in the magnetic recording / reproducing apparatus includes, for example, a rotating drum 41 having a magnetic head on the outer peripheral surface and a fixed drum (not shown) fixed. When the magnetic head scans the magnetic tape 42 by the rotation of the rotary drum 41, writing and reading of signals are performed. FIG. 4 shows a part of the drum device 40 in an enlarged manner.
Numeral 3 is provided on the rotating drum 41 as a magnetic head for reading signals, and contacts a running magnetic tape 42 to detect a recording signal.

If the cassette case around which the magnetic tape 42 is wound is charged with static electricity, as shown in FIG. 4, the surface of the magnetic tape 42 passes through the MR head 43 in contact with the magnetic tape 42 to the ground of the apparatus. This causes a flow of the electrical charge 44 through. For example, at the start of the reproducing operation of the magnetic recording / reproducing apparatus, the cassette case is inserted into the magnetic recording / reproducing apparatus, and the magnetic tape 42 is brought closer to the rotating drum 41 by the movement of the guide mechanism, and the magnetic tape 42 comes into contact with the MR head 43 At that moment, a large amount of current flows through the MR element, causing electrostatic destruction of the MR element and making it impossible to read signals. For this reason, conventionally, the magnetic tape 4
It was difficult to use the MR head 43 as the magnetic head of the recording / reproducing apparatus using the No. 2.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to prevent electrostatic breakdown of an MR head in a magnetic recording / reproducing apparatus having the MR head.

[0010]

According to the present invention, there is provided a magnetic recording and reproducing apparatus for recording and reproducing signals on and from a magnetic tape. A front panel is provided with an opening for insertion and ejection of a cassette case in which is wound and stored, has an electrical resistance value of 0 Ω to 1 × 10 ¹² Ω, and is electrically connected to the mechanical chassis. And a magnetic recording / reproducing apparatus characterized by having the following.

In such a magnetic recording / reproducing apparatus, the front panel is made conductive with an electric resistance value of 0Ω to 1 × 10 ¹² Ω and is electrically connected to the mechanical chassis, so that the cassette case charged with static electricity is inserted. In this case, when the magnetic tape is discharged to the ground through the front panel that comes into contact with the ground and the magnetic tape subsequently comes into contact with the magnetoresistive element, it is possible to prevent occurrence of electrostatic breakdown of the magnetoresistive element.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 2 shows a schematic configuration example of a magnetic recording / reproducing apparatus of the present invention.

A magnetic recording / reproducing apparatus 1 shown in FIG. 2 uses a magnetic tape 2 as a recording medium and is used as, for example, a data storage device of a computer device or a recording device of a video signal or an audio signal. The running system of the magnetic tape 2 in the magnetic recording / reproducing apparatus 1 includes a drum device 3 having a magnetic head for writing and reading signals to and from the magnetic tape 2 in a mechanical chassis 1a, and a magnetic tape 2 at a predetermined speed. The capstan 4 and the pinch roller 5 to be run, and a plurality of tape guides for guiding the running of the magnetic tape 2 (indicated as TG in the figure)
6a, 6b, 6c, 6d and 6e. The cassette case 7 inserted into the magnetic recording / reproducing apparatus 1 has a supply reel 7a and a take-up reel 7b for the magnetic tape 2, and is held by a cassette mechanism 8 which is movable by driving a motor (not shown).

The drum device 3 has a cylindrical shape having a smooth outer peripheral surface as a whole, and includes, for example, a rotating drum (not shown) at an upper portion and a fixed drum (not shown) fixed to a mechanical chassis 1a coaxially with the rotating shaft. Be composed. The rotating drum is driven to rotate by a drum motor (not shown) provided in the fixed drum. Further, the rotating drum is provided with a reproducing magnetic head (not shown) for detecting a recording signal of the magnetic tape 2 and a recording magnetic head (not shown) for writing a signal. The reproducing magnetic head is an MR head using a magnetoresistive effect (MR) element as a head element, and contacts a magnetic tape 2 to detect a change in the resistance value of the MR element according to a recording signal. Then, the recording signal of the magnetic tape 2 is read. The recording magnetic head is a so-called inductive type magnetic head in which a coil is wound around a magnetic core having a magnetic gap, for example. Usually, a plurality of the reproducing heads and the recording heads are mounted on a rotating drum.

On the other hand, the capstan 4, the supply reel 7a and the take-up reel 7b are driven to rotate by a capstan motor (not shown), whereby the magnetic tape 2 runs. The capstan 4 and the supply reel 7
a and the take-up reel 7b may be rotationally driven by separate motors. Further, the pinch roller 5 and the TGs 6 a to 6 e constitute a thread mechanism for performing an operation of pulling out the magnetic tape 2 from the inside of the cassette case and winding it around the drum device 3.

In this magnetic recording / reproducing apparatus 1, when recording and reproducing of the magnetic tape 2 are performed, the cassette case 7 is inserted into the magnetic recording / reproducing apparatus 1 in the direction of arrow A from an opening provided in the front panel 9. It is inserted, held by the cassette mechanism 8 and automatically moved, and set at a position where recording and reproduction operations are possible. After this, the drum device 3
As the rotating drum rotates, the loading operation of the magnetic tape 2 is started, and the pinch roller 5 and the TGs 6a to 6e move in the direction of arrow B in the drawing by the driving of the sled mechanism, whereby the magnetic tape 2 is guided. It is helically wound around the drum device 3. Further, the magnetic tape 2 travels by rotating the capstan 4 and the take-up reel 7b, and the recording head or the reproducing head scans the magnetic tape 2 obliquely by the rotation of the rotating drum, thereby recording. Writing or reading of a signal is started.

The cassette case 7 used in the magnetic recording / reproducing apparatus 1 is made of a high-resistance synthetic resin material. , Or easily rubs against various parts when inserted into the magnetic recording / reproducing apparatus 1, thereby easily charging static electricity.
When the magnetic tape 2 is loaded onto the drum device 3 while the cassette case 7 is charged with static electricity in this way, the magnetic tape 2 comes into contact with the outer peripheral surface of the drum device 3 and has an MR element. In some cases, the magnetic head is brought into contact with the reproducing magnetic head and discharged from the charged cassette case 7 through the magnetic tape 2 to the reproducing magnetic head, thereby causing electrostatic breakdown of the MR element. In the present invention, in order to prevent the electrostatic breakdown of the MR element occurring for such a reason,
The front panel 9 into which the cassette case 7 is inserted is made conductive and is electrically connected to the ground of the magnetic recording / reproducing apparatus 1, so that static electricity is gradually discharged through the front panel 9.

FIG. 1 shows an example of the configuration of the front panel in the magnetic recording / reproducing apparatus 1. Front panel 9
In the panel body 9a, an eject (EJECT) button 9b for ejecting the cassette case 7, an LED (Light Emitting Diode) 9c for displaying the operation status, and an opening 9d for inserting and ejecting the cassette case 7 are provided.
The opening 9d is provided with an opening / closing lid 9e pressed by a spring or the like on the panel body 9a side. The panel main body 9a is fixed to the mechanical chassis 1a with metal fixing screws 9f.

In the front panel 9, the panel body 9a has conductivity and is fixed to the mechanical chassis 1a by a conductive fixing member such as a metal fixing screw 9f. Chassis 1a is electrically connected. The mechanical chassis 1a is set to the ground potential.

With such a structure of the front panel 9, when the cassette case 7 charged with static electricity is inserted into the opening 9d, or when the cassette case 7 is inserted, it comes into contact with and rubs against various parts to generate static electricity. In this case, the cassette case 7 and the panel body 9a come into contact with each other through the opening 9d, and the static electricity is discharged to the ground. Therefore, when the cassette case 7 is subsequently set at the recording and reproducing operation position and the magnetic tape 2 is loaded on the drum device 3 and comes into contact therewith, it is avoided that a large current flows through the MR element and electrostatic breakdown occurs. You. Further, in addition to the panel body 9a, the opening / closing lid 9e may be made conductive. By electrically connecting the opening / closing lid 9e to the panel body 9a, the contact area with the inserted cassette case 7 is reduced. As a result, the efficiency of discharging static electricity is increased.

In order to provide the panel body 9a and the opening / closing lid 9e with a high discharge performance against static electricity, the electric resistance is desirably 0Ω to 1 × 10 ¹² Ω. In order to make the panel body 9a and the opening / closing lid 9e conductive, they are formed of, for example, a resin material or a metal material. Specific examples of the conductive material applicable to the present invention include, for example, a tin oxide-based material in which tin oxide is doped with antimony, an indium oxide-based material in which indium oxide is doped with tin, and an oxide in which zinc oxide is doped with aluminum or the like. A zinc-based material, stainless steel, and a conductivity-imparting composition obtained by mixing and attaching conductive zinc oxide fine powder to natural organic fiber powder such as pulp disclosed in Japanese Patent Application Laid-Open Publication No. 2821762 are mixed with a resin material. The obtained conductive resin material is desirable. Further, as a specific product name, “Grade“ TP4 with Toray ABS resin antistatic agent ”
0 ″ ”or the like is desirable. This “TP40” is used for injection molding and the like.
Since a manufacturing method substantially similar to that of the insulating resin material can be used, the moldability is excellent and the manufacturing cost can be suppressed.

The panel body 9a and the opening / closing lid 9e
As a method for imparting conductivity to the substrate, a material having an antistatic film provided on a resin material or the like may be used.
Specific examples of such an antistatic film include, for example, a tin oxide-based material in which tin oxide is doped with antimony, an indium oxide-based material in which indium oxide is doped with tin, and a zinc oxide-based material in which zinc oxide is doped with aluminum or the like. In addition to an antistatic film using, a patent publication "JP-A-2000-186"
218 ", a water-soluble conductive polyaniline,
Water-soluble conductive polymers such as water-soluble conductive polypyrrole, water-soluble conductive polythiophene, water-soluble conductive polyparaphenin, and water-soluble conductive polyparaphenylenevinylene, and sulfonic acid, glycol, polyethylene glycol, hydroxyl group, and carboxyl in the molecule Antistatic film formed by using a conductive resin composition comprising a modified polyester resin containing a hydrophilic group such as a group, and the like.
An antistatic film formed using a conductive resin composition in which a phenolic antioxidant is added to a composition comprising a polyarylate and a conductive filler disclosed in "0-169885", a utility model publication " 6-2004
0 ", an antistatic film formed by vacuum-depositing a material of the fourth period element such as Cr, Cu, Fe, Co, Ni, etc .;
An antistatic film formed by using the conductive resin material disclosed in “62” is desirable.

In the above description, an example in which the present invention is applied to the magnetic recording / reproducing apparatus 1 using the magnetic tape 2 has been described. However, the present invention relates to a magnetic reproducing apparatus capable of reproducing only the magnetic tape 2. It is also possible to apply to.

[0024]

As described above, in the magnetic recording / reproducing apparatus of the present invention, the front panel has an electric resistance of 0Ω to 1Ω.
Since it is electrically connected to the mechanical chassis with a conductivity of × 10 ¹² Ω, when a cassette case charged with static electricity is inserted, it is discharged to ground through the front panel that comes into contact with it, and then the magnetic tape is When contacting the resistance effect element, it is possible to prevent the occurrence of electrostatic breakdown of the magnetoresistance effect element.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a front panel in a magnetic recording / reproducing apparatus of the present invention.

FIG. 2 is a diagram showing a schematic configuration example of a magnetic recording / reproducing apparatus of the present invention.

3A and 3B are diagrams showing measurement results of an ESD breakdown voltage in an MR head, where FIG. 3A is an AMR head, and FIG.
The measurement results for the R head are shown respectively.

FIG. 4 is a diagram conceptually showing a flow of charges when a magnetic tape and an MR head come into contact with each other.

[Explanation of symbols]

1 ... magnetic recording / reproducing device, 1a ... mechanical chassis, 2 ...
... Magnetic tape, 3 ... Drum device, 4 ... Capstan, 5 ... Pinch roller, 6a-6e ... Tape guide, 7 ... Cassette case, 7a ... Supply reel, 7b
... take-up reel, 8 ... cassette mechanism, 9 ... front panel, 9a ... panel body, 9b ... eject button, 9c ... LED, 9d ... opening, 9e ...
Opening / closing lid, 9f ...... Fixing screw

Claims (5)

[Claims] 1. A magnetic recording and reproducing apparatus for recording and reproducing signals on and from a magnetic tape, comprising: a mechanical chassis set to a ground potential; and a cassette case in which the magnetic tape is wound and stored. Opening is provided for
A magnetic recording / reproducing apparatus, comprising: a front panel having an electric resistance value of 1 × 10 ¹² Ω and electrically connected to the mechanical chassis. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the front panel is formed of a conductive resin material. 3. The magnetic recording / reproducing apparatus according to claim 1, wherein the front panel has an antistatic film formed on a surface thereof. 4. The magnetic recording and reproducing apparatus according to claim 1, wherein the front panel is formed of a metal material. 5. The magnetic recording / reproducing apparatus according to claim 1, wherein a magnetoresistive head is used as a reproducing magnetic head for reading a recording signal of the magnetic tape.