CN1052389A

CN1052389A - Apparatus for demagnetizing magnetic head

Info

Publication number: CN1052389A
Application number: CN90108291A
Authority: CN
Inventors: 铃木宪一; 山本充弘
Original assignee: Audio Technica KK
Current assignee: Audio Technica KK
Priority date: 1989-12-09
Filing date: 1990-10-10
Publication date: 1991-06-19
Also published as: GB2238913A; GB9026791D0; JPH03181012A; KR920000048A; JP2808029B2

Abstract

A kind of is the apparatus for demagnetizing magnetic head of the recording and the reproducing head degaussing of cassette tape recorder, when the cassette shell of this device being put into sound-track engraving apparatus and setting recording or playback modes, the startup of auto stop structure, avoided and with the enough time be the magnetic head degaussing.This device comprises: the cassette shell with a pair of nave collar, this is suitable for installing to the sound-track engraving apparatus tape side to nave collar and send on the rotation axis of band side, at least one neutral gear is set between two nave collars in this housing, and this rotation to one of nave collar passed to another, the erasing head of electromagnetism system contacts with the recording of sound-track engraving apparatus, reproducing head, a degaussing driving circuit makes erasing head produce a predetermined alternating magnetic field, makes battery connect the degaussing driving circuit selectively by rotating switch.

Description

Apparatus for demagnetizing magnetic head

The present invention relates to a kind of device that is used for to the magnetic head degaussing, specifically, the apparatus for demagnetizing magnetic head that relates to is suitable for the recording and the reproducing head degaussing of cassette tape recorder.

Proposed diversified apparatus for demagnetizing magnetic head at present, made the recording and the playback performance degradation of audio tape in order to prevent magnetization owing to the magnetic head of casette deck.As a kind of device that utilizes the boxlike casing, such as, be disclosed in Japanese Patent Application 58-10765 number, the device on (deliver February 28 nineteen eighty-three).The apparatus for demagnetizing magnetic head of representing in the above-mentioned communique comprises: (the degaussing electromagnet of the spigot of (magnetic) head can move on front and rear direction for recording that is arranged on the boxlike casing and playback; One is used for making the degaussing electromagnet to produce the driving circuit of predetermined alternating magnetic field at the boxlike casing; And a switch, it is recorded and reproducing head makes drive circuit works when depressing at the degaussing electromagnet.According to above-mentioned device, when this boxlike casing was loaded into cassette tape recorder and sets recording or playback modes, the recording of this cassette tape recorder and reproducing head just contacted with the degaussing electromagnet and connect switch, and like this, magnetic head is by self-demagnetization.But this conventional technology of using has following shortcoming:

That is to say, although the degaussing driving circuit is to move by the recording and the loading of reproducing head to be switched on and to disconnect, even the boxlike casing that degaussing is used is put into cassette tape recorder, since the turning axle of winding one side be not to connect mutually sending turning axle by tape with a side, therefore the rotation of winding one side rotating shaft is not delivered to the rotating shaft of sending with a side, like this, one stops (automatically rewinding) mechanism automatically and has just moved, and magnetic head is reset in other words, and magnetic head has no action before carrying out degaussing.

The purpose of this invention is to provide a kind of apparatus for demagnetizing magnetic head that is suitable for the recording and the reproducing head degaussing of cassette tape recorder; wherein when the boxlike casing being put into cassette tape recorder and is set playback or during record type, the startup of autoshutoff device avoided and also magnetic head inevitable by with the time enough degaussing.

This invention comprises: a cassette shell, and it has a pair of nave collar to be suitable for installing to the rotating shaft of cassette tape recorder winding one side and send in the rotating shaft with a side; In this cassette shell at least one neutral gear be arranged on this to nave collar between and the rotation of a nave collar passed to another nave collar; The erasing head that a kind of electromagnet of usefulness is made contacts with the recording and the reproducing head of cassette tape recorder; A degaussing driving circuit produces predetermined alternating magnetic field to erasing head; And battery it optionally be connected to the degaussing driving circuit by a rotating switch.For top structure, because this is connected by the neutral gear running nave collar, in recording or tone playing state, the rotation of the turning axle of winding one side is passed to the turning axle that send with a side, so can prevent the auto-stop mechanism action.

Brief description of drawings of the present invention is as follows:

Fig. 1 is the plan view of expression by the apparatus for demagnetizing magnetic head inner structure of one embodiment of the present of invention;

Fig. 2 is a decomposition diagram, in order to the neutral gear shown in the key drawing 1 and the assembled state of rotating switch;

Fig. 3 is the circuit that an expression is used for the driving circuit of degaussing

Consult accompanying drawing below and describe one embodiment of the invention in detail.

Fig. 1 is a plan view, has pulled down first box body and can see the inner structure of cassette shell 1 in the state of its expression.According to this figure, the erasing head made from a kind of electromagnet 3 is arranged on the recording of cassette shell 1 and reproducing head and inserts in mouthfuls 2, so that go up removable in front and rear direction (among Fig. 1 vertical direction).In the case, two supports is arranged on the back of erasing head 3 at a bar-spring 4 of cassette shell 1.This erasing head 3 is pressed to the front side by spring 4.This as, also can adopt a volute spring at bar-spring 4 places.Offering rotating shaft through hole 5a and 5b on nave collar 6a and the 6b.Nave collar 6a and 6b itself are known devices, and it is meshed with the turning axle of cassette tape recorder (not shown) and is rotated.But,, be with gear 7a and 7b on nave collar 6a and the 6b according to this embodiment.A neutral gear 8 is being set so that the rotation of one of gear 7a and 7b is passed to another between gear 77a and the 7b.Among this embodiment,, also can install a plurality of neutral gears though installed a neutral gear 8.On the other hand, having the circuit board 9 of degaussing driving circuit and the 1.5V battery of using as power supply 10 is installed in the cassette shell 1.In such cases, power supply 10 adopts a kind of button battery.Except corresponding to this of rotating shaft through hole 5a and 5b to the through hole, as shown in Figure 2, the through hole 9b that runs through the turning axle 8a of neutral gear 8 forms on the circuit board 9.

Among Fig. 1, because above-mentioned this is not shown through hole week gear 7a and blocking of 7b.On the other hand, the pin 11 of rotating shaft 8a of a supporting neutral gear 8 is vertically formed in the cassette shell 1 and the corresponding position of through hole 9b.Rotating switch 12 is arranged between neutral gear 8 and the circuit board 9 as the switch of degaussing driving circuit.

Now also consult the structure of accompanying drawing 3 explanation rotating switches 12 and a kind of structure of degaussing driving circuit.This degaussing driving circuit comprises: one comprises and battery 10(1.5V) control circuit 15 of the rotating switch 12 that switches on and off; An amplifying circuit 16 that amplifies battery 10 voltages; And an oscillatory circuit 17, it is connected on the back level of amplifying circuit 16 and makes erasing head 3 can produce a predetermined alternating magnetic field.

Rotating switch 12 comprises: the first fixed contact 12a, and it is connected to the base stage of switch triode TR1; Second decides contact 12b, and it is connected to capacitor C ₁(for example, specified voltage is set to 6.3V, and electrostatic capacitance is set at 470 μ F) is with to triode TR ₁Apply a predetermined base voltage; The 3rd fixed contact 12C, it connects battery, 10; And a moving contact 12d, it makes capacitor C ₁Convert to or connect triode TR ₁Perhaps connect battery 10.

Consult Fig. 2 again, the second fixed contact 12b is shaped around through hole 9b on the circuit board 9, and the first fixed contact 12a forms in the outside of the second fixed contact 12b coaxially.In the case, the first fixed contact 12a is not an annulus, but is processed into the cut C font of a part.In addition, the 3rd fixed contact is set at one almost on the concentric circles of the center between the first fixed contact 12a two ends.This moving contact 12d comprises: first a sliding contact 12d who always slides on the second fixed contact 12b ₁; With one do than the first sliding contact 12d ₁The second long sliding contact 12d ₂So that on the first fixed contact 12a and the 3rd fixed contact 12C, slide.Moving contact 12d makes and is fixed to the turning axle 8a of neutral gear 8 upward so that play rotation with one with the rubber-like sheet metal.Therefore, when moving contact 12d rotates, capacitor C ₁Not only can charging modes but also can discharge mode be transformed into the base stage of triode TR1.Amplifying circuit 16 comprises: a step-up transformer T ₁; A connection transformer T ₁Secondary triode TR ₂; A LED 1 that shows charged state; A capacitor C ₂(such as, rated voltage is set at 16V, and static capacity is set at 220 μ F); A supervision capacitor C ₂The voltage stabilizing diode ZD1 of voltage; Thyristor (controllable silicon) SCR of a conducting under Zener voltage (15V); And LED ₂Be used for luminous demonstration discharge condition when the controllable silicon SCR conducting.The voltage stabilizing diode ZD2 that Zener voltage is set at 2V is connected between LED 1 and the oscillatory circuit 17.

This oscillatory circuit 17 has: a capacitor C who is used for degaussing ₃(rated voltage is set at 16V, and static capacity is set at 47 μ F); And a pair of triode TR4 and TR4 since the controllable silicon SCR conducting this to alternately conducting and ending of triode.Two coil 3a of erasing head 3 and the link a of 3b～d are received the output terminals A～D of this circuit respectively with suitable lead.

When demagnetizer was packed into cassette tape recorder and startup recording or playback knob, the magnetic head (not shown) just contacted from the lower position rising of Fig. 1 and with erasing head 3.Rotating shaft in the rotating shaft of winding one side is delivered to the rotating shaft of sending with a side by neutral gear 8.The startup of autoshutoff device is then avoided.Rotation by neutral gear 8 is rotated moving contact 12d, and the voltage of battery 10 is amplified to a predetermined voltage by amplifying circuit 16.

In other words, as the second sliding contact 12d ₂When being positioned on the 3rd fixed contact 12c, capacitor C ₁Be recharged.As the second sliding contact 12d ₂When being connected across on the first fixed contact 12a, by capacitor C ₁Provide base voltage and this triode TR1 conducting to triode TR1.Like this, the voltage of battery 10 is by transformer T ₁Boost and be accumulated in capacitor C ₂On.At this moment, LED 1 luminous and indication capacitor C ₂Be recharged.

To capacitor C ₂The rotation of charging by moving contact 12d repeat several times.As capacitor C ₂Voltage reached voltage stabilizing diode ZD ₁Zener voltage (15V) time, controllable silicon SCR is conducting just, is accumulated in capacitor C ₂On electric charge discharged and the triode TR of oscillatory circuit 17 to degaussing capacitor C3 ₃With TR ₄Alternately conducting and ending.So, produce an alternating magnetic field by erasing head 3.When the controllable silicon SCR conducting, LED ₂Send light, be carried out thereby indicate degaussing.

In this embodiment, can not adopt big transformer because the space in the cassette shell 1 is limited, so the boost in voltage process will repeat several times, the voltage of battery 10 just can rise to 15V.Yet, if can have relative large space, just a plurality of batteries can be installed or use a kind of big transformer or similar device, thus the degaussing voltage that once to need.

Claims

1, a kind of device that is used for to the magnetic head degaussing is characterized in that comprising: the cassette shell with a pair of nave collar, this nave collar are suitable for installing to the rotating shaft of tape type sound-track engraving apparatus winding one side and send in the rotating shaft with a side; At least one neutral gear, it is arranged in the cassette shell this between the nave collar and this rotation to one of nave collar is passed to another nave collar; An erasing head made from electromagnet, it contacts with the recording and the reproducing head of cassette tape recorder; A degaussing driving circuit is used to make erasing head to produce an alternating magnetic field; And a battery, it optionally is connected to the degaussing driving circuit by a switch.

2, a kind of by the described device of claim 1, it is characterized in that this switch is a kind of rotating switch, is provided with one heart with neutral gear.