JPH03181012A - Degausser of magnetic head - Google Patents

Abstract

PURPOSE:To allow the sure execution of degaussing by providing at least one intermediate gear which transmits the rotation of one of a pair of hubs to the other between the hubs and coaxially disposing a switch as a rotary switch on this intermediate gear. CONSTITUTION:The intermediate gear 8 which transmits the rotation of one of the gears 7a and 7b to the other is provided between these gears and the rotary switch 12 as the switch of a driving circuit for degaussing is provided between the intermediate part 8 and a circuit board 9. The magnetic head rises from below and comes into contact with a degaussing head 3 when a recording or reproducing button is operated. The rotation of a tape take-up side revolving shaft is then transmitted via the intermediate gear 8 to a tape delivery side revolving shaft an the operation of an auto-stop mechanism is averted. Further, a traveling contact 12d is rotated by the rotation of the intermediate gear 8 and the voltage of a battery 10 is amplified up to a prescribed voltage by an amplifier circuit 16. The magnetic head is surely degaussed with sufficient time in this way.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a magnetic head degaussing device, and more specifically, to a magnetic head degaussing device suitable for degaussing a recording/playback head of a cassette tape recorder. It is.

[Conventional technology]

The magnetic head of a tape deck becomes magnetized when recording and playback are repeated over a long period of time. If this becomes severe, not only will noise increase and high frequency output drop, but noise may also be introduced into the recording tape.

Therefore, various magnetic head degaussers (head eraser,
demagnetizer) has been proposed, but examples using a cassette case include the
There is one based on Publication No. 5. To briefly explain this configuration, a degaussing electromagnet is provided in the recording/playback head insertion slot of the cassette case so as to be movable in the front and back direction, and a drive circuit that generates a predetermined alternating current magnetic field in the degaussing electromagnet is provided in the case, and The device is configured to include a switch that activates the drive circuit when the electromagnet is pushed in by the recording/playback head.

According to this, when the cassette case is loaded into a cassette tape recorder and put into playback or recording mode, the recording/playback head of the tape recorder comes into contact with the degaussing electromagnet, and the switch is turned on to automatically demagnetize it. will be held.

[Problem to be solved by the invention]

In the above conventional example, the degaussing vibration circuit is opened and closed by the loading operation of the recording/playback magnetic head.
Even if this degaussing cassette case is loaded into a cassette tape recorder, the tape winding side rotation axis and the tape delivery side rotation axis are not connected via the tape, so the tape winding side rotation axis is the same. If the rotation is not transmitted to the rotating shaft when the tape is fed out, the auto-stop (auto-reverse) mechanism may be activated and the magnetic head may be reset before degaussing is completed.

[Means to solve the problem]

In order to solve the above problems, in this invention.

The cassette case is equipped with a pair of knobs that fit into the tape winding rotation axis and the tape delivery rotation axis of the cassette tape recorder. A degaussing device for a magnetic head comprising: a degaussing head; a degaussing drive circuit for generating a predetermined alternating current magnetic field in the degaussing head; and a battery selectively connected to the degaussing drive circuit via a switch. , located between a pair of hubs.

It has at least one intermediate gear that transmits the same rotation of one to the other, and the switch 1 is arranged as a rotary switch coaxially with the intermediate gear.

[For production]

As mentioned above, since the pair of hubs are operatively connected by an intermediate gear, during playback or recording, the rotation of the tape winding rotation axis is transmitted to the tape delivery rotation axis, and the auto-stop mechanism operation is avoided. Further, by combining the intermediate gear and the rotary switch, each component can be rationally arranged within the limited space of the cassette case.

〔Example〕

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows a plan view of the cassette case 1 with the -L side cassette half removed so that the internal structure of the cassette case 1 can be seen. According to this, the recording/playback head insertion slot 2 of the cassette case 1 has a degaussing head 3 made of an electromagnet.
are arranged so as to be movable in the front-rear direction (vertical direction in FIG. 1). in this case,? A rod-shaped spring 4 whose both ends are supported by the cassette case 1 is arranged behind the i'1 magnetic head 3, and the demagnetizing head 3 is urged forward by this spring 4. Note that instead of the rod-shaped spring 4, for example, a coil spring may be used.

The hub 6 is inserted into the rotating shaft insertion holes 5a and 5b of the cassette case (
a and 6b are provided. The hubs 6a, 6b themselves are of a known type that fits on and rotates the 1!71 rotating shafts of a cassette tape recorder (not shown), but according to this embodiment, the hubs 6a, 6b cost $11. (7a, 7
b is installed. Between these gears 7a and 7b,
An intermediate gear 8 is provided which transmits the rotation of one to the other. In this example, there is one intermediate gear 8, but there may be a plurality of intermediate gears 8.

Further, the cassette case 1 houses a circuit board 9 having a degaussing drive circuit and a 1.5V battery 10 as its power source. In this case, a button-type battery is used as the battery 10.The circuit board 9 has a rotating shaft insertion hole 5a.
, 5b, an insertion hole 9b for inserting the co-rotating shaft 8a of the intermediate gear 8 is provided, as shown in FIG. Note that the pair of through holes are not shown in FIG. 1 because they are hidden by the gears 7a and 7b.In addition, in relation to the insertion hole 9b, the cassette case 1 has a support for the rotating shaft 8a of the intermediate gear 8. A bottle 11 is set upright.

A rotary switch 12 is provided between the intermediate gear 8 and the circuit board 9 as a switch for a degaussing drive circuit. Here, the configuration of the rotary switch 12 and the configuration of the degaussing immediate action 101 path will be explained with reference to FIG.

The degaussing calling circuit includes a control circuit 15 that includes the rotary switch 12 that turns on and off the battery 10 (1.5V).
, an amplifier circuit 16 for amplifying the voltage of the battery 10 , and an oscillation circuit 17 connected to the subsequent stage for generating a predetermined alternating current magnetic field in the degaussing head 3 .

The rotary switch 12 has a first fixed contact 12 connected to the base of the switching transistor TRI.
a, capacitor C1 (rated voltage 6.3V, electrostatic field bl:
470 μF), a third fixed contact 12c connected to the battery 10, and a movable contact 12d for switching the capacitor C1 to either the transistor TRI or the battery IO.

Referring again to FIG. 2, the second fixed contact 12b is formed in an annular shape around the push-through hole 9b on the circuit board 9, and the first fixed contact 12a is formed on the outer side thereof in a coaxial manner. It is formed. In this case, the ↓ fixed contact 12
A is not ring-shaped, but is formed into a C-shape with a portion thereof missing. Further, the third fixed contact 12c is arranged on a concentric circle approximately at the center between both ends of the first fixed contact 12a.

The movable contact 12d includes a first sliding contact 12d that always slides on the second fixed contact 12b, and a first fixed contact 12a.
and the first lever sliding on the third fixed contact 12c.
This movable contact 12cl is longer than the sliding contact 12d1 (formed second sliding contact 12d).
It is made of a metal plate with spring elasticity.

It is attached to the rotating shaft 8a of the intermediate gear 8 so as to rotate therewith. Therefore, by rotating the movable contact 12d, the capacitor CI is switched to either the transistor TRI or the battery 10.

The amplifier circuit 16 includes a step-up transformer TI, a transistor TR2 connected to its secondary side, a light emitting diode LHD I for displaying charging status, a capacitor C2 (rated voltage 6V, capacitance jit 220μF), and the same capacitor C2.
A constant voltage diode ZDI that monitors the voltage of 2 and a thyristor SCR that conducts at its Zener voltage (15V)
and a light emitting diode LED2 for displaying the discharge state that emits light when the thyristor 5CI is conductive. Note that between the light emitting diode LHDI and the oscillation circuit 17,
A constant voltage diode ZD2 with a Zener voltage of 2.5 cm is connected.

The oscillation circuit 17 is connected to a demagnetizing capacitor C3 (rated voltage 16
V, electrostatic field Jit47μF) and the above thyristor SC
It has a pair of transistors TR3 and TR4 that are turned on and off alternately when R becomes conductive, and its output terminal A
-D, the connection terminals a'' and d of the two coils 3a and 3b of the demagnetizing head 3 are connected, for example, through appropriate connectors.

Load this degaussing device into a cassette tape recorder and record a
Alternatively, when the playback button is operated, a magnetic head (not shown) rises from the bottom of FIG. The rotational speed is transmitted to the rotating shaft, and the operation of the auto-stop mechanism is avoided. The rotation of the intermediate gear 8 causes the movable contact 12d to rotate, and the voltage of the battery IO is amplified to a predetermined voltage in the amplifier circuit I6.

That is, the second sliding contact 12d2 is the third fixed contact 1.
2c, capacitor C1 is charged.

The second sliding contact 12d is the first fixed contact 1.
2a, the base voltage is supplied from the capacitor CI to the transistor TRI, and the transistor T
RI turns on. As a result, the voltage of the battery 10 is boosted by the transformer T1 and stored in the capacitor C2.

At this time, the light emitting diode LHDI emits light to indicate that it is in a charging state.

Due to the rotation of the movable contact 12d, charging of the capacitor C2 is repeated several times, and the resulting voltage is applied to the constant voltage diode zDl.
When the Zener voltage reaches (15V), the thyristor S
CR becomes conductive, the charge accumulated in the capacitor C2 is supplied to the degaussing capacitor C3, and the transistors TR3 and TR4 of the oscillation circuit 17 are turned on and off alternately. As a result, an alternating current magnetic field is generated from the demagnetizing head 3, and the magnetic head is demagnetized. Note that due to the conduction of the thyristor SCR,
The light emitting diode LED 2 emits light to indicate that demagnetization has been performed.

In this embodiment, due to space constraints within the cassette case 1, a very large transformer cannot be used.
The voltage of the battery IO is increased to, for example, 15V by repeating the step-up several times, but if space is available, the desired degaussing can be achieved at once by mounting multiple batteries or using a larger transformer. It may also be possible to obtain a voltage.

〔Effect of the invention〕

As explained above, according to the present invention, the pair of hubs of the cassette case are operatively connected via the intermediate gear, so that during playback or recording, the tape winding mli'1 rotation is performed. Since the 1='1 rotation of the shaft is transmitted to the tape feeding surveying rotary shaft, the auto-stop mechanism is operated simultaneously, and the magnetic head can be reliably demagnetized in sufficient time.

Further, by combining the intermediate gear and the rotary switch, effects such as being able to rationally arrange each component within the limited space of the cassette case are achieved.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the internal structure of an embodiment of the magnetic head degaussing device according to the present invention, and FIG. 2 is a plan view showing the combination of the intermediate gear and rotary switch shown in FIG. 1. The exploded perspective view and FIG. 3 are circuit diagrams of the degaussing drive circuit. In the figure, 1 is a cassette case, 3 is a degaussing head, 4 is a spring, 6a, 6b are hubs, 7a, 7b are gears, 8 is a middle confederate, 9 is a circuit board, 10 is a battery, 12 is a rotary switch, 15 1 is a control circuit, 16 is an amplifier circuit, and 17 is an oscillation circuit.

Claims (1)

[Claims] (1) A cassette case having a pair of hubs that fit into the tape winding side rotating shaft and the tape sending side rotating shaft of the cassette tape recorder, and inside the cassette case, abuts against the recording/playback head of the tape recorder. Demagnetizing a magnetic head comprising a demagnetizing head made of an electromagnet, a demagnetizing drive circuit that generates a predetermined alternating current magnetic field in the demagnetizing head, and a battery selectively connected to the demagnetizing drive circuit via a switch. A magnetic head having at least one intermediate gear disposed between the pair of hubs and transmitting the rotation of one of the hubs to the other, and the switch being a rotary switch disposed coaxially with the intermediate gear. degaussing device.