JPS59117749A - Position detector of rotary magnetic head - Google Patents

Abstract

PURPOSE:To make the assembling of a PG coil easy by fitting the PG coil onto a board supporting a motor driving a rotary magnetic head and providing a recessed part accommodating the PG coil on an outer face of a fixed cylinder. CONSTITUTION:The PG coil 14 wound on a bobbin 13 is fitted to a position opposite to an outer end face of a lower fixed cylinder of a motor board 12. On the other hand, the recessed part 15 accommodating the PG coil 14 is provided to a position opposite to the PG coil 14 of the outer end face supporting the motor board 12 of the lower fixed cyliner 11. Through the constitution above, the assembling process of the PG coil is performed at the same time as the fitting process of the motor board, and no soldering in the cylinder is required at all after the PG coil is assembled. Thus, the assembling of the PG coil is made easy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a position detection device for a rotating magnetic head in a helical scan VTR.

[Technical background of the invention and its problems]

As is well known, the rotating magnetic head mechanism in a helical scan VTR consists of a rotating disk provided between a fixed upper cylinder and a lower cylinder, and a plurality of magnetic heads (rotating magnetic heads) mounted on an upper rotating cylinder that straddles the cylinder. These rotating magnetic heads come into sliding contact with a magnetic tape that slides helically on its circumferential surface, recording video signals.
It has a structure that supports regeneration.

In this type of device, it is necessary to add a service mechanism to the rotating magnetic head, and for this purpose, it is necessary to accurately detect the position of the head. This position detection is generally performed magnetically by a magnet provided on a rotating body (disk) that rotates together with the rotary head, and a PG coil provided on a fixed cylinder to face the magnet.

FIG. 1 shows the configuration of a conventionally employed position detection device for a rotating magnetic head. This is done by forming a recess (spot hole) 2 in the inner wall of the lower fixed cylinder 1, and inserting an iron core 3 into this recess 2.
A PG coil 6, which has been previously wound around a bobbin 4 and whose end is soldered to a terminal 5, is installed therein.

A lead wire (not shown) is soldered to the terminal 5, and this lead wire is led out of the cylinder 1 through a hole (not shown) formed in the lower fixed cylinder 1.

However, with this structure, various problems will occur as the cylinder becomes smaller in order to make VTRs smaller in the future.

That is, since the wiring work (soldering) of the lead wire to the terminal 5 of the PG coil 6 is done inside the cylinder 1,
During work, the outer circumferential surface of the cylinder, on which the tape slides, is easily damaged, and if the PG coil 6 or lead wire breaks inside the cylinder, the cylinder must be disassembled. Furthermore, a large space is required to incorporate the PG coil 6 into the cylinder, which also becomes an obstacle to downsizing the cylinder.

[Purpose of the invention]

The circuit of the present invention provides a rotating magnetic head position detection device that can easily incorporate a PG coil even when the cylinder is downsized, has excellent workability and maintainability, and is highly reliable. .

[Summary of the invention]

This invention provides a recess for accommodating the PC coil on the outer surface of the fixed cylinder that supports the motor board on the outer end surface, and the PG coil is mounted on the substrate that supports the motor that rotationally drives the rotary magnetic head. [Effects of the Invention] According to this invention, the PG coil can be assembled into the cylinder by attaching the PC coil to the motor board in advance and mounting the motor board to the cylinder. Furthermore, the wiring of the PG coil can be done in advance on the motor board. Therefore, even if the cylinder becomes smaller, the PG coil can be easily assembled, and there is no risk of damaging the outer peripheral surface of the cylinder due to wiring work. Furthermore, even if the PG coil or its wiring breaks, there is no need to disassemble the cylinder, making maintenance easier. Furthermore, since no space is required for mounting the PG coil inside the cylinder, the cylinder can be further downsized.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the present invention, in which (a) is an exploded perspective view and (b) is a sectional view of the main part. In the figure 1
1 is a lower fixed cylinder, 12 is a motor board, and a rotating magnetic head ( It supports a motor (not shown) that rotationally drives a motor (not shown). The lower fixed cylinder (i) of this motor board 12
A PG coil 14 wound around a bobbin 13 is attached at a position facing the outer (lower side in the figure) end surface.

The coil end of the PG coil 14 is connected to the surface of the motor board 12 on the side opposite to the cylinder 11 side by soldering.

On the other hand, a recess (spot hole) 15 for accommodating the PG coil 14 is provided at a position facing the PG coil 14 on the outer end surface of the lower fixed cylinder 11 that supports the motor board 12 . Also, what is inside the recess 15? The hollow part of the bottle 13 is made of fitting iron. When assembling, first, the PG coil 14 is wound around the bobbin 13 and fixed onto the motor board 12 by means of adhesive or the like, and the coil end of the PG coil 14 is connected to the motor board 12. On the other hand, an iron core 16 is press-fitted or glued into the recess 15 of the lower fixed cylinder 11. After making such preliminary preparations, the motor board 12 is fixed onto the outer end surface of the lower fixed cylinder 11 by means such as screws. At this time, the PC coil 14
The bobbin 13 wound with is accommodated in the recess 15 and fitted onto the iron core 16.

In this way, the PG coil 13 is incorporated into the cylinder mechanism.

A disk is provided in the cylinder mechanism to rotate together with the rotating magnetic head, and a magnet (not shown) is placed on the disk at a position corresponding to the rotating magnetic head.
is installed.

Then, when the rotating magnetic head rotates, the magnetic field of the magnet acts on the PG coil 13, so that the PG coil 13 generates a curve indicating the position of the rotating magnetic head.

With the above configuration, the PC coil installation process can be performed at the same time as the motor board installation process, and there is no need for any soldering inside the cylinder after the P'G coil is installed. . There is still no P in the cylinder.
There is no need to provide a hole for passing the lead wire from the G coil.

Therefore, according to the present invention, workability, maintainability, and reliability can be improved, and it can greatly contribute to downsizing of cylinders.

In addition, in this invention, the PG coil may be bobbinless, and in that case, the mounting space can be further saved.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are exploded perspective views and cross-sectional views illustrating the configuration of a conventional rotating magnetic head position detection device, and FIGS. FIG. 2 is an exploded perspective view and a sectional view showing the configuration. 11... Lower fixed cylinder, 12... Motor board, 1
3...Bobbin, 14...PG coil, 15...recess,
16... Iron core. Applicant's representative Patent attorney Takehiko Suzue Figure 1 (b) Figure 2 (a) (b)

Claims (3)

[Claims] (1) The position of the rotating magnetic head that comes into contact with the magnetic tape sliding on the cylinder circumferential surface is set at a fixed position opposite to the magnet provided on the rotating body that rotates together with the head. In a detection device using a PG coil, the PG coil is mounted on a motor board that supports a motor that rotationally drives a rotating magnetic head, and the PG coil is mounted on the outer end surface of a fixed cylinder that supports the motor board on the outer end surface. , a position detection device for a rotating magnetic head, characterized in that a recessed portion for accommodating a PG coil is provided. (2) The position detecting device for a rotating magnetic head according to claim 1, wherein the PG coil is connected to the surface of the motor board opposite to the fixed cylinder side. (3) What about the PG coil? 2. A position detecting device for a rotating magnetic head according to claim 1, wherein the device is bottleless.