JPS6213214Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic head shield device suitable for application to a magnetic recording/reproducing device that processes information using digital signals, particularly a PCM magnetic recording/reproducing device.

A magnetic head of a magnetic recording/reproducing apparatus that records and reproduces digital signals is constructed as shown in FIG. 1, for example. Reference numeral 1 denotes a first recording magnetic head in which the head gaps of a large number of stacked magnetic head chips are aligned in the width direction of the magnetic tape as shown by the dashed line. When the recording state of the magnetic tape is detected, similarly formed reproducing heads 2 are installed with a head gap of 25.4 mm from each other, and adjacent to this reproducing magnetic head 2, a similarly formed reproducing head 2 is used to record the recording leakage portion of the magnetic tape. The second recording magnetic heads 3 thus formed are provided with head gaps separated from each other by 12 mm. Here, the magnetic tape is sequentially transferred to a first recording magnetic head 1, a reproducing magnetic head 2, and a second recording magnetic head 3, and the first recording magnetic head 1 receives a predetermined signal to be recorded. Digital information is recorded on the magnetic tape, and this recorded signal is reproduced by the reproducing magnetic head 2 to detect whether there is any recording leakage. If there is a recording omission, the second recording magnetic head 3 further corrects the signal and records the signal on the magnetic tape as digital information.

By the way, in the above-mentioned operation, the gap between the reproduction magnetic head 2 and the second recording magnetic head 3 is very close to each other, approximately 12 mm. The leakage magnetic flux of the recording signal of the head 3 is transferred to the reproducing magnetic head 2.
This has the drawback that the signal-to-noise ratio of the reproduced signal deteriorates when the magnetic tape reaches the end of the recording period, making it impossible to reliably detect the presence or absence of recording leakage on the magnetic tape.

Therefore, in order to prevent leakage magnetic flux from reaching the reproducing magnetic head 2, at least when recording the magnetic tape, the second recording magnetic head 3 and the reproducing magnetic head 2 are
It is necessary to shield the front of the Furthermore, the magnetic head shield plate must be stored in a position where it does not interfere with the application of the magnetic tape to the magnetic head.

Therefore, conventionally, a thin plate-shaped magnetic head shield plate has been designed to be movable in a direction perpendicular to the surface on which the head gap of the magnetic head is provided, or parallel to the surface on which the head gap is provided, or freely rotatable in the vicinity, i.e. 1
It is mounted in two degrees of freedom and is positioned in front of the magnetic head to shield the magnetic head during recording on magnetic tape.

However, in the case of a magnetic head shield plate for a PCM magnetic recording and reproducing device, for example, a gold-plated copper plate for electrical shielding and a ferrite chip for magnetic shielding installed inside the plate are connected to the magnetic head shield holding plate via a leaf spring. The magnetic head shield plate itself is relatively thick, and it is difficult to move the magnetic head shield plate with one degree of freedom as described above.

In view of this, the present invention has been developed by first raising the magnetic head shield plate, which takes a relatively long time by pulling a string, from a storage position where it does not interfere with the application of magnetic tape to the magnetic head, and then horizontally moving it. It is an object of the present invention to propose a magnetic head shield device that can be moved to quickly come into contact with a magnetic head.

An example of the magnetic head shield device according to the present invention will be described in detail below with reference to FIGS. 2 to 6.

Reference numeral 4 denotes a fixed part that is integrally attached to the panel chassis 5, and a first link 8 and a second link are provided at the lower part of the side parts 6 and 7 that are bent downward at the front (left side in FIG. 5). The lower ends of the links 9 are rotatably attached to each other, and the upper ends of a movable part 10 having a U-shaped cross section are rotatably attached to the upper ends of the first link 8 and the second link 9 through engagement holes 11 and 12. installed on.

13 is stretched between the protruding part 14 of the fixed part 4 and the second link 9, that is, the movable part 10, and is normally connected to the second link.
The link 9, ie, the movable member 10, is a spring having elasticity to shift the movable member 10 in the forward direction (to the left in FIG. 4, etc.) with respect to the fixed part 4. Reference numeral 16 denotes a rotating part, which consists of a shaft 17 and a pulley 18 that is rotationally attached integrally with the shaft 17.
It is rotatably attached to 0. A string 32 is wound around the pulley 18, and one end of the string 32 is connected to a driving device (not shown) such as a plunger. Reference numeral 19 denotes a weight, which is attached to the rear portion of the shaft 17. Reference numeral 25 denotes a magnetic head shield holding plate, and on the rear side (on the right side in the figure), as shown in FIG. In particular, the electric shield member 28 is arranged to be in contact with the front surfaces of the magnetic heads 1, 2, and 3 described above. The electrical shielding member 28 is made of copper, for example, and is in direct contact with the magnetic head housing 29 to form a closed loop of one turn of an electrical circuit, thereby obtaining a shielding effect due to copper loss. On the other hand, the magnetic shielding member 27 is made of ferrite, and although it does not necessarily have to be in contact with the magnetic head housing 29, it is designed to obtain a magnetic shielding effect on the head gap surface of the magnetic head housing 28. .

The magnetic head shield holding plate 25 is connected to the above-mentioned movable portion 10 via the first and second connecting rods 22 and 24. That is, both connecting rods 22, 2
One end of each of the magnetic head shield holding plates 25
The first
The other end of the second connecting rod 22 is attached so as to be rotationally integrated with the shaft 17 attached to the above-mentioned movable part 10, and the other end of the second connecting rod 24 is rotatably attached to the shaft 17 attached to the movable part 10. It is mounted so that it can move freely. 30
is a through hole for attaching the other end of this second connecting rod 24. In this case, a line (shown in FIG. 2) a connecting both ends (both rotation center points) of the first connecting rod 22
and b of the second connecting rod 24 are configured such that each connecting rod 22, 24 rotates while always maintaining a parallel state.

Next, the operation of the above-described configuration will be explained. FIG. 2 is an exploded perspective view of this device in its negative state, that is, before it is used as a shield plate, and the solid line in FIG. 4 is a side view in this state.

When the string 32 is pulled in the direction of arrow C by a drive device (not shown) composed of a plunger or the like, the pulley 1
8 rotates clockwise, and as the shaft 17 rotates, the first connecting rod 22 rotates clockwise to raise the magnetic head shield holding plate 25. The magnetic head shield holding plate 25 projects from the window 31 of the panel 5 to the upper surface of the panel 5. At this time, the connecting rods 22, 24
move in parallel, so the magnetic head shield holding plate 2
5 rises while maintaining the vertical position. and,
At the position where the opposite sides of the first connecting rod 22 and the second connecting rod 24 abut, this rotation is stopped and the lifting of the magnetic head shield holding plate 25 is also stopped. The two-dot chain line in FIG. 4 indicates this state.

Furthermore, since the pulley 16 cannot rotate when the string 32 is pulled, the movable part 10 moves in the direction of arrow b against the elasticity of the panel 13 and is held in that state by the drive device. Due to this movement of the movable part 10, the magnetic head shield holding plate 25 also moves as indicated by the arrow b.
The magnetic head shield plate 27 and the electric shield plate 28 attached thereto come into contact with the magnetic head housing 29, and the magnetic head 1,
A few electrical and magnetic shields are provided (see Figure 5).

As a result, leakage magnetic flux of the recording signal from the second recording magnetic head 3 reaches the reproduction magnetic head 2 during recording on the magnetic tape, and the signal-to-noise ratio of the reproduction signal deteriorates. Erroneous detection of the presence or absence of recording omissions can be avoided.

Next, when the power to the plunger as a driving means is removed and the string is loosened, the movable part 10 is moved by the spring 13.
moves in the direction of arrow a, and the magnetic head shield plate 2
5 is separated from the magnetic head housing 29 (the fourth
(See the two-dot chain line in the figure).

When the string 32 is further loosened, the magnetic head shield plate 25 and the first connecting rod 22 that are in contact with each other are removed.
and the second connecting rod 24 are lowered, the magnetic head shield plate 25 returns to its original state with its top facing the window 31 of the panel 5, and the first connecting rod 22 and the second connecting rod 24 return to their original state. That is, the state returns to the state shown by the solid line in FIG.

Therefore, the tension of the spring 13 is selected to be such that the movable part 10 does not move when the holding plate 25 is raised by pulling the string 32 for the first time.

Thus, according to the magnetic head shield device according to the present invention, by driving the drive device at least during the recording operation of the magnetic recording/reproducing device with a simple configuration, the magnetic head shield plate is pulled by pulling the string connected to the movable member. Since the magnetic head can face the magnetic head, leakage magnetic flux of the recording signal of the second recording magnetic head does not reach the reproduction magnetic head during recording on the magnetic tape, and the signal-to-noise ratio of the reproduction signal is prevented from deteriorating. Therefore, erroneous detection of the presence or absence of recording leakage on the magnetic tape can be avoided.

Furthermore, when the magnetic head shield plate is constructed of a magnetic shield member that is in contact with the magnetic head housing and a magnetic shield member that is made of a magnetic material, the magnetic head can be shielded more reliably.

In addition, with one action of pulling the string, the magnetic head shield plate can be raised from the storage position where it does not interfere with the hanging of the magnetic tape on the magnetic head, and the magnetic head shield plate can be moved horizontally to the magnetic head.

Further, the installation location of the plunger that performs the action of pulling the string can be arbitrarily selected.

Furthermore, when the first connecting rod and the second connecting rod are used as a link mechanism, smooth operation can be achieved, the locus of movement of the magnetic head shield plate is accurate, and there is little play.

Note that the first connecting rod and the second connecting rod do not stop rotating when their sides collide with each other, but rather the magnetic head shield retaining plate is engaged by a rising stop means provided on the upper part thereof. It may be stopped at the same time.

[Brief explanation of the drawing]

Figure 1 is a front view of the magnetic head, Figures 2 and 3 are
The figure is an exploded perspective view of the magnetic head shield device according to the present invention, FIGS. 4 and 5 are side views of the magnetic head shield device, and FIG. 6 is a sectional view of the magnetic head shield device. 4 is a fixed part, 10 is a movable member, 13 is a spring, 1
6 is a rotating member, 22 is a first connecting rod, 24 is a second
connecting rod, 25 is a magnetic head shield holding plate, 3
2 is a string.

Claims (1)

[Claims for Utility Model Registration] 1. A fixed part, a movable part attached to the fixed part so as to be able to move substantially in parallel, a spring stretched between the fixed part and the movable part, and the movable part a rotating part rotatably attached to the rotating part; a first connecting rod having one end rotatably attached integrally to the rotating part;
A second connecting rod, one end of which is rotatably attached to the movable part and arranged parallel to the first connecting rod, is rotatable at the other ends of the first connecting rod and the second connecting rod. It consists of a freely attached magnetic head shield holding plate and a string connected to the rotating part, and by pulling the string, the first and second connecting rods are rotated, and then the movable part is rotated. A magnetic head shield device in which the magnetic head shield plate is brought into contact with a housing of a magnetic head by moving it against a spring. 2. The magnetic head shield plate according to claim 1 of the above-mentioned utility model registration is composed of an electric shield member that comes into contact with the magnetic head housing and a magnetic shield member made of a magnetic material.