JPH07129936A - Magnetic head and its grounding method - Google Patents

Abstract

PURPOSE:To provide magnetic head which has the high strength of adhesion between a head space and a flexible printed circuit board(FPC) and has excellent performance stability by simplifying the positioning of the printed circuit board relative to the head base. CONSTITUTION:The head base 2 adhered with a head chip 4 is fixed by means of a screw 3 to a rotary cylinder 1. The head base 2 is provided with through- holes 10a, 10b and the FPC 6 is also provided with bored holes 9a, 9b so as to correspond to this. Mounting of the FPC 6 to the head base 2 is conducted by inserting a pin-shaped positioning member 11 into the through-hole 10 and the bored hole 9 to position the member and fixing the member by an adhesive material. The one end of a winding 5 is grounded to the rotary cylinder 1 side if the positioning member 11 is composed of a conductor in such a case. The FPC 6 does not disengage from the head base 2 even if the centrifugal force of the rotary cylinder 1 increases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head mounted on a rotary cylinder of a magnetic recording / reproducing apparatus and a method of grounding the magnetic head.

[0002]

2. Description of the Related Art A magnetic recording / reproducing apparatus (for example, VT) for recording / reproducing by sliding a magnetic head against a magnetic tape.
In R), the head chip of the magnetic head is provided with a winding for performing electromagnetic conversion. One end of the winding is soldered to a conductor portion near the head chip of the printed circuit board, and the other end of the winding is soldered to another conductor portion. The lead wires connected to these conductors are connected to a signal amplification circuit, a rotary transformer, etc. in the rotary cylinder. For example, in a VHS standard VTR, a glass epoxy material is usually used for a printed circuit board on a head base, and an organic adhesive such as a thermosetting epoxy resin or an ultraviolet curing resin is used for adhesion to the head base. .

In the meantime, in order to realize the high recording rate of the VTR in the recent trend of high density recording, a method of increasing the relative speed of the tape head is usually adopted. Therefore, high-speed rotation of the rotary cylinder is essential. When the rotary cylinder rotates at a high speed in this way, an extremely large centrifugal force acts on the outer peripheral portion of the rotary cylinder, so that it is necessary to firmly attach each component mounted on the rotary cylinder.

In the case of a consumer VTR such as VHS, the number of parts attached to the rotary cylinder is small, and the probability of occurrence of defects due to soldering is low. On the other hand, in the case of a multi-channel digital VTR for realizing a high transmission rate, the probability of occurrence of defects increases due to an increase in the number of soldering points. Therefore, in such a VTR, it is becoming mainstream to perform line processing collectively using a flexible printed circuit board.

As a method for fixing the flexible printed circuit board to the head base, conventionally, the substrate and the head base have been bonded and fixed to each other via an organic adhesive or a double-sided adhesive tape. Further, as in Japanese Utility Model Laid-Open No. 5-21696, a resin coating hole is formed at a common position between the flexible printed circuit board and the mounting component, and an organic adhesive is coated through this hole to simplify the mounting. There are also things.

[0006]

However, in the case of this example, the positioning accuracy of the printed circuit board can be improved and the mounting can be simplified, but since the flexible printed circuit board is covered with a polyimide film or a polyester film,
The adhesiveness with the organic adhesive is poor, and it is easy to peel off due to the centrifugal force that accompanies the high speed rotation of the rotary cylinder. Further, there is a drawback that applying an organic adhesive to an adhesion surface of a head base or a printed board, which is generally performed, or improving positioning accuracy by using a double-sided tape is a complicated process. Further, there is a drawback that the adhesion reliability is gradually reduced when the centrifugal force by the rotating cylinder is repeatedly applied as a load.

On the other hand, in a VTR having a rotary cylinder equipped with a signal amplifier circuit or a VTR having a wide recording band, it is necessary to ground one signal line of the reproducing head to the rotary cylinder near the head chip. In the conventional grounding method, it is general that the lead wire is drawn from the printed board on the head base and soldered to the ground wire, or the rotary cylinder is screwed together and grounded. These methods have a drawback in that the performance of the magnetic head is lacking in stability because the distance from the head chip to the lead wire becomes long.

According to the conventional method, when a load repeatedly applied or a very large centrifugal force is applied, the adhesion reliability of a flexible printed circuit board having poor adhesiveness or a commonly used printed circuit board is lowered. Therefore, there is a drawback that the head performance becomes unstable.

The inventions according to claims 1 to 3 of the present application have been made in view of such conventional problems, and the positioning of the printed board with respect to the head base is simplified, and the adhesive strength between the head base and the printed board is improved. It is intended to realize a magnetic head having high stability and excellent stability. It is another object of the invention of claim 4 of the present application to realize a grounding method which is excellent in stability of terminals of a magnetic head.

[0010]

The invention according to claim 1 of the present application is a plate-shaped member attached to the outer peripheral portion of a rotary cylinder, wherein a head base is provided with through holes at a plurality of positions in the thickness direction, A magnetic head chip attached to the tip of the head base, a hole attached to one side of the head base and formed at a position facing the through hole of the head base, and a conductor connecting the ends of the windings of the magnetic head chip. And a printed circuit board having a circuit pattern connected to the conductor section, and a positioning member that is inserted into the perforation of the printed circuit board and the through hole of the head base to position the printed circuit board. is there.

In the invention of claim 3 of the present application, the printed circuit board is characterized in that a buried wiring for electrically connecting the conductor portion and the perforation is formed.

According to a fourth aspect of the present invention, the conductor portion of the printed circuit board is grounded to the rotary cylinder side via the conductive positioning member and the embedded wiring.

[0013]

According to the invention of claim 1 of the present application having such a feature, the through hole is provided in the head base, and the printed circuit board is fixed through the positioning member. Therefore, the rotary cylinder rotates at high speed, and even if the centrifugal force increases, the printed circuit board does not move toward the outer peripheral side of the rotary cylinder.
Further, when mounting the printed circuit board on the head base, the positioning accuracy is improved.

According to the third aspect of the present invention, since the positioning member has conductivity, the end of the winding can be grounded near the head chip. Therefore, the ground resistance is reduced, and the performance of the magnetic head is stabilized.

Further, according to the invention of claim 4 of the present application, when the printed board is attached to the head base, accurate positioning can be performed only by inserting the holes of the printed board into the positioning member. Also, one of the windings of the head chip is grounded to the rotary cylinder via the positioning member, so that a new grounding lead wire is not required.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic head according to a first embodiment of the present invention and a method of grounding its terminals will be described with reference to FIGS. 1A and 1B show a peripheral portion (hereinafter referred to as a magnetic head portion) of a magnetic head in the first embodiment, wherein (a) is a front view and (b) is a side view. As shown in FIG. 1 (b), the head cylinder 2 has screws 3 on the rotary cylinder 1 of the VTR.
Installed by As shown in FIG. 1A, the head base 2 is formed by integrally forming a substantially square plate-shaped member and a wedge-shaped protrusion 2a, and is made of, for example, brass.

A magnetic head chip (hereinafter referred to as a head chip) 4 is fixed to a portion of the protrusion 2a facing the recess 1a of the rotary cylinder 1. An organic adhesive such as a thermosetting epoxy resin is used for this fixing. The head chip 4 is a magnetic head in which a winding 5 having a wire diameter of, for example, several tens of μm is balancedly wound on a magnetic core, and is a magnetic head for recording or reproducing a signal on a magnetic tape. A flexible printed circuit board (FPC) 6 is attached to the upper surface of the head base 2. The flexible printed circuit board 6 has a substantially concave shape, the outer peripheral portion thereof is slightly smaller than the outer peripheral portion of the head base 2, and the inner peripheral portion thereof is notched in an arch shape so as to avoid the head of the screw 3. The flexible printed board 6 is formed of a polyimide film, a polyester film, or the like.

As shown in FIG. 1A, the flexible printed circuit board 6 has a conductor portion (land) 7 made of copper foil.
a, 7b and circuit patterns such as lines 8a, 8b connected to them. The ends of the winding 5 are soldered to the conductors 7a and 7b. Further, perforations 9a and 9b are opened in the left and right corners of the flexible printed circuit board 6. Also, through holes 10a and 10b are formed in the head base 2 at the same positions as the holes 9a and 9b, respectively. Then, the positioning member 1 is attached to the perforations 9a and 9b and the through holes 10a and 10b.
1 is inserted. The positioning member 11 is a pin-shaped member made of metal or resin. The flexible printed circuit board 6
The lines 8a and 8b are connected to a signal processing circuit and a rotary transformer (not shown) in the rotary cylinder 1.

A procedure for attaching the respective parts of the magnetic head portion thus constructed will be described with reference to FIG. FIG. 2 is an exploded perspective view showing a method of attaching the head base 2 and the flexible printed circuit board 6. First, the head chip 4 is adhesively fixed to the protrusion 2 a of the head base 2, and the positioning member 11 is inserted into the through holes 10 a and 10 b of the head base 2. In this case, the amount of protrusion of the positioning member 11 from the head base 2 is approximately the thickness of the flexible printed circuit board 6. The positioning member 11 is press-fitted or fixed by resin so that it does not protrude from the cylinder mounting reference surface (arrow A) of the head base 2.

Next, an epoxy adhesive is applied to the back surface (arrow B) of the flexible printed board 6 and the flexible printed board 6 is inserted into the positioning member 11 through the holes 9a and 9b. Then, the head base 2 and the flexible printed circuit board 6 are pressure-bonded using a jig (not shown), and heated to cure. Although the adhesive application surface is the back side of the flexible printed circuit board 6, it may be the upper surface of the head base 2. By assembling the magnetic head portion in this way, the positioning of the flexible printed circuit board 6 with respect to the head base 2 becomes easy. Further, even if a centrifugal force due to the rotation of the rotary cylinder 1 acts, the flexible printed circuit board 6 is fixed by the positioning member 11 so that it cannot be finely moved in the radial direction of rotation, so that the adhesive force of the adhesive does not deteriorate.
The end of the winding 5 is stably connected to the circuit section.

A magnetic head according to the second embodiment of the present invention,
A method of grounding the terminal and its terminal will be described with reference to FIG. 3A and 3B show the peripheral portion of the magnetic head in the second embodiment, where FIG. 3A is a front view and FIG. 3B is a side view. In this figure, the same parts as those in the first embodiment are designated by the same reference numerals,
Descriptions thereof are omitted.

Unlike the first embodiment, the embedded wiring 20 is provided on the flexible printed board 6. One conductor portion 7a of the flexible printed board 6 is electrically connected to the rotary cylinder 1 through the perforations 9a and the embedded wiring 20. The embedded wiring 20 is a conductor formed between the layers or the back surface of the flexible printed circuit board 6, and is a wiring that grounds the conductor portion 7 a on the surface to the rotary cylinder 1. Next, the positioning member 2
Reference numeral 1 is a pin-shaped member having conductivity such as copper or copper plating. The positioning member 21 is fixed in contact with the head base 2 made of brass, for example, by press fitting or soldering.

To mount each component in the magnetic head portion having such a structure, the flexible printed circuit board 6 is inserted into the head of the positioning member 21 through the holes 9a and 9b and soldered. That is, the head chip 4 is indexed and positioned on the rotary cylinder 1, and one end of the winding 5 is grounded to the rotary cylinder 1. Normal,
When the head chip 4 is indexed, a shim having a predetermined thickness is laid between the rotary cylinder 1 and the head base 2 because it is necessary to accurately adjust the track height.
Since the shim is made of stainless steel such as SUS304, the head base 2 itself is grounded to the rotary cylinder 1.

The through holes 10 formed in the head base 2 are milled or simultaneously punched by a die like a VHS head base. Therefore, the positional accuracy of the through hole 10 is sufficiently ensured. Further, since the flexible printed circuit board 6 is also punched by pressing after the pattern of the conductor portion 7 and the like is formed, the positional accuracy of the perforations 9 is ensured similarly to the head base 2.

In the above description, the organic adhesive is applied to the bonding surfaces of the head base 2 and the flexible printed circuit board 6 when they are positioned, but it is applied because a plurality of terminals of the flexible printed circuit board 6 are connected. You don't have to. However, it goes without saying that the adhesive reliability is improved by using the organic adhesive. The adhesive may be a commonly used epoxy resin or UV curable resin. In the case of an epoxy resin, a thermosetting epoxy resin has higher adhesive strength and is more preferable than a room temperature curing type.

When a flexible printed circuit board including a glass epoxy printed circuit board is used, the anchoring effect, that is, the mechanical bonding effect is also added because the surface roughness of the adhesive surface is large, so the adhesive strength is further increased. Get higher However, in the case of a flexible printed circuit board covered with a polyimide film or the like, its surface property is good and the adhesive strength is basically low. It goes without saying that it will improve.

In each of the above embodiments, the positioning member 1
The fixing of 1, 21 to the head base 2 has been described as press-fitting or soldering of a conductive member, or adhesion by resin, but the fixing method may be welding by laser irradiation, mechanical fixing by screws, or the like. I do not care. Alternatively, the positioning members 11 and 21 may be fixed to the head base 2, inserted into the perforations 9 of the flexible printed board 6 for positioning, and then the positioning member may be irradiated with laser light and fixed by welding. That is, the positioning members 11 and 21 do not have to remain in the original shape, and may be fixed in a molten state. Further, the head base 2 and the positioning member 1
The reference numerals 1 and 21 do not have to be individual, and a convex portion may be integrally formed as a positioning member like a molded product, and the flexible printed circuit board 6 may be fixed via the convex portion.

[0028]

As described above, according to the first and second aspects of the present invention, since the printed circuit board is attached to the head base through the mounting member, the repeated load and the large centrifugal force due to the rotation of the rotary cylinder are provided. On the other hand, the adhesion reliability is increased.

According to the invention of claim 3 of the present application, in addition to the effects described above, since one end of the winding of the magnetic head chip is grounded through the positioning member, the length of the ground line is long. Becomes shorter. Therefore, the influence of noise is reduced, and the performance of the magnetic head becomes stable.

Further, according to the invention of claim 4 of the present application,
Positioning accuracy of the print substrate and head base is improved, and it is less susceptible to noise. Further, there is an effect that the winding of the magnetic head can be easily grounded.

[Brief description of drawings]

FIG. 1 is a front view and a side view showing a configuration of a magnetic head portion in a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a method of mounting the magnetic head unit according to the first and second embodiments of the present invention.

3A and 3B are a front view and a side view showing a configuration of a magnetic head portion in a second embodiment of the present invention.

[Explanation of symbols]

 1 Rotating Cylinder 1a Recess 2 Head Base 2a Projection 3 Screw 4 Head Chip 5 Winding 6 Flexible Printed Circuit Board 7a, 7b Conductor 8a, 8b Line 9a, 9b Perforation 10a, 10b Through Hole 11, 21 Positioning Member 20 Embedded Wiring

Claims (4)

[Claims] 1. A head base, which is a plate-shaped member mounted on an outer peripheral portion of a rotary cylinder, having through holes provided at a plurality of positions in a thickness direction, and a magnetic head chip mounted on a tip portion of the head base. A hole attached to one surface of the head base, the hole being formed at a position facing the through hole of the head base, the conductor portion connecting the ends of the windings of the magnetic head chip, and the conductor portion. A magnetic head comprising: a printed circuit board having the circuit pattern described above; and a positioning member that is inserted into the perforations of the printed circuit board and the through holes of the head base to position the printed circuit board. 2. The magnetic head according to claim 1, wherein the positioning member is a member having conductivity. 3. The magnetic head according to claim 1, wherein the printed circuit board is provided with embedded wiring for electrically connecting the conductor portion and the hole. 4. The method for grounding a magnetic head according to claim 3, wherein the conductor portion of the printed circuit board is grounded to the rotary cylinder side via the conductive positioning member and the embedded wiring.