JPS647403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cassette-type magnetic head demagnetizer, and more particularly to a cassette-type magnetic head demagnetizer suitable for demagnetizing a recording/playback head of a cassette tape recorder.

The recording/reproducing head of a tape recorder becomes magnetized after long-term use, resulting in deterioration of the recording/reproducing characteristics. To avoid this deterioration, it is necessary to periodically demagnetize the magnetic head. For this reason, cassette cases have already been put into practice in which a degaussing circuit or the like is incorporated into the cassette case for easy use. As shown in FIG. 6, a degaussing electromagnet 44 supported from the back by a leaf spring 43 is disposed in a recording/playback head insertion window 42 of a cassette case 41, and the degaussing electromagnet 44 is supported by a leaf spring 43 from the back side. Lever 47 of switch 46 that is turned on when electromagnet 44 is pushed back
is made to respond to the elastic deformation of the leaf spring 43, and at the same time as the switch 46 is turned on, an alternating current magnetic field that attenuates over time is generated from a degaussing circuit (not shown) via the degaussing electromagnet 44 in an instant. I was trying to make it happen in my house.

By the way, in this type of tape recorder, in addition to the operation type in which the magnetic head moves directly in the front-rear direction, there is also a type in which the magnetic head rotates. The degaussing operation must be started with good head contact.

However, in the conventional configuration described above, the operating energy of the switch 46 is taken from the leaf spring 43 that supports the degaussing electromagnet 44. Therefore, in the case of a tape recorder in which the magnetic head rotates, the magnetic head 45 is a demagnetizing electromagnet 44
There is a risk that the switch 46 will be turned on via the leaf spring 43 at the same time as the magnetic head 45 and the demagnetizing electromagnet 44 are contacted obliquely. Bad sex.

Therefore, the present invention has changed the method of obtaining the operating energy of the switch from the spring supported by the degaussing electromagnet, and the change in tension of the strip disposed across the pinch roller of the tape recorder and the capstan within the cassette case. It is an object of the present invention to provide a cassette type magnetic head demagnetizing device which can reliably perform a demagnetizing operation regardless of the operating method of the magnetic head by operating a switch at the same time.

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, reference numeral 1 denotes a cassette case made of synthetic resin or the like, and this case 1 has drive shaft through holes 2 and 3 formed therein through which a drive shaft (not shown) of a cassette tape recorder passes, and a front wall. There is an erase head insertion window 3 and a recording/playback head insertion window 4.
and a pinch roller insertion window 5 are formed respectively. 6 is a degaussing electromagnet disposed within the recording/playback head insertion window so as to be movable in the front and back direction;
This degaussing electromagnet 6 is biased forward by an elastic member such as a leaf spring 7 provided behind it, and a non-magnetic cover such as a synthetic resin tape is attached to the front surface. The above-mentioned non-magnetic cover 8 prevents the recording/reproducing head 9 of the tape recorder from directly contacting the degaussing electromagnet 6, and both 9, 6.
This is to prevent damage to the product.

Reference numeral 10 designates a wiring board disposed inside the cassette case 1, which includes a well-known degaussing circuit 11 shown in FIG.
Elements 12 constituting the are set. That is, in FIG. 2, 13 is a power supply battery, 14 is a DC-DC converter that boosts the terminal voltage of the power supply battery 13, 15 is a large-capacity capacitor that is charged with the DC output voltage from the converter 14, and 16 is the above-mentioned degaussing capacitor. an oscillation circuit whose load is the winding 17 of the electromagnet 6;
A switching circuit 18 connects the capacitor 15 to the oscillation circuit 16 when the capacitor 15 is charged.

In FIG. 1, reference numeral 19 is a belt-shaped body made of synthetic resin film, etc., and this belt-shaped body 19 is connected to the pinch roller 20 of the tape recorder and the capstan 20.
The cassette case 1 is intersected by a locking piece 22 in the cassette case 1, and is held in a loose state at one point. Reference numeral 23 denotes a power switch consisting of a micro switch with an operating lever, etc. provided near the strip 19, and this switch 23 is connected to the pinch roller 20 and the capstan 21.
When the part 19a on the rear side in the rolling contact direction of the strip body 19 changes to a tensioned state due to the rolling contact drive, the degaussing circuit is closed via the actuating lever 24 driven by the tensioning force of this part 19a. 11 is designed to close the circuit. In addition, in this example,
One part of the strip 19 is locked to a locking piece 22 inside the cassette case 1, but the micro switch 2
3, that is, the actuating lever 24 as the actuating part of the switch 23.
It is also possible to cut a portion of 9 into a modified loop shape, and lock one end of the loop into the case and the other end of the loop to the operating lever 24.

In the above configuration, when it is not attached to a cassette tape recorder, the degaussing electromagnet 6 is in the forward position due to the spring force of the leaf spring 7, as shown in FIG. It is in an open state because it remains in the same state.

When the device is attached to a cassette tape recorder and the cassette tape recorder is set to recording or playback mode, the recording/playback head 9 of the cassette tape recorder opens into the cassette case 1 as shown in FIG.
The demagnetizing electromagnet 6 is pressed by entering the recording/reproducing head insertion window 4 of the head. As a result, the demagnetizing electromagnet 6
The recording/reproducing head 9 is moved back against the spring force and is brought into close contact with the recording/reproducing head 9 through the non-magnetic cover 8 on the front surface thereof. Furthermore, when the tape recorder is set to recording or playback mode, the pinch roller 2
0 and the capstan 21 drive the band-shaped body 19 into rolling contact, as shown in FIG.
gradually becomes tense. This tension change in the strip 19 operates the operating lever 24 of the switch 23 and closes the switch 23, thereby closing the degaussing circuit 11. That is, the capacitor 15 is charged by the DC output of the DC-DC converter 14 that boosts the terminal voltage of the power supply battery 13, and at the same time that the capacitor 15 becomes fully charged, the switching circuit 18 detects this and switches the capacitor 15. The accumulated charges are discharged to the oscillation circuit 16. The terminal voltage of capacitor 15 decreases over time. Therefore, the degaussing electromagnet 6, which is excited by the oscillation output of the oscillation circuit 16, generates an alternating magnetic field that is initially strong enough for demagnetization but attenuates over time, so that the recording and reproducing head 9 can absorb the alternating current magnetic field. It will be demagnetized.

Here, since the operating mechanism of the switch 23 is separated and independent from the degaussing electromagnet 6, the backward movement of the degaussing electromagnet 6 when pressed by the recording/playback head 9 of the tape recorder is balanced and smooth. In addition, the switch 23 is turned on and the degaussing operation is started after the head 9 properly contacts the degaussing electromagnet 6 regardless of the operating method when the head 9 moves forward.
It is also easy to time the operation of step 3. In the above embodiment, the switch 23 is operated by utilizing the tensioned state of the band 19, but it is also possible to utilize the relaxed state of the band 19. An example will be explained with reference to FIGS. 4 and 5.

The movable contact piece 25 of the leaf spring type switch 27 has a movable contact piece 25 and a fixed contact piece 26 facing each other.
One end of the strip 19 is fixed to the
is passed between the pinch roller 20 and the capstan 21, and the other end is fixed inside the cassette case 1 via a tension spring 28. When not in use, the tension spring 28 holds the tape in the form of a band, as shown in Fig. 4. The body 19 is in tension and the movable contact piece 25 is in a fixed contact piece 26
However, during use, the belt-shaped body 19 is pulled in the opposite direction to the tensioning direction of the tension spring 28 due to the rotational drive between the pinch roller 20 and the capstan 21, and from this rotational contact position, Band-shaped body 19
The portion 19a on the movable contact piece 25 side is relaxed. In this way, the movable contact piece 25 contacts the fixed contact piece 26 by its own elasticity and becomes conductive, and the degaussing circuit 11 is driven.

By the way, if the strip 19 is made of a cleaning material, dirt adhering to the capstan 21 can be removed by rolling contact with the pinch roller 20.

As described above, in this invention, the switch is turned on by changing the tension of the strip driven by the pinch roller and the capstan, so that the magnetic head of the tape recorder can properly contact the degaussing electromagnet regardless of its operating method. It is possible to provide a cassette-type magnetic head demagnetizer that can perform a demagnetizing operation from the beginning and can reliably perform demagnetization.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a cassette-type magnetic head demagnetizing device according to the present invention, with the upper case of the cassette removed, FIG. 2 is a block diagram showing the electrical configuration of the device, and FIG. 3 is the same diagram. FIGS. 4 and 5 are partial plan views showing other modifications of the main parts, and FIG. 6 is an explanatory diagram of a conventional example. DESCRIPTION OF SYMBOLS 1... Cassette case, 4... Magnetic head insertion window, 6... Demagnetizing electromagnet, 11... Demagnetizing circuit, 19
...Band-shaped body, 19a...Tension changing part, 20...
Pinch roller, 21... Capstan.

Claims (1)

[Claims] 1 A degaussing electromagnet 6 is disposed within the magnetic head insertion window 4 of the cassette case 1 so as to be movable back and forth in response to a forward spring force, and a state in which the degaussing electromagnet 6 is pressed against the recording/playback head 9 of the tape recorder. in,
A degaussing circuit 11 generates in the degaussing electromagnet 6 an alternating current magnetic field that is initially strong enough for degaussing but attenuates as time passes, and the degaussing circuit 11 generates an alternating current magnetic field in the degaussing electromagnet 6 at a position that crosses the pinch roller 20 and capstan 21 of the cassette tape recorder. A switch is operated to close the degaussing circuit 11 by a tension change in a portion 19a of the band 19 disposed in the cassette case 1, and a portion 19a of the band 19 caused by the rolling contact drive between the capstan 20 and the pinch roller 21. 23 (27).