JPH07161002A - Magnetic recording device - Google Patents

Abstract

(57) [Summary] [Purpose] By making the recording bias frequency and the switching frequency of the switching power supply the same, no special noise countermeasures are required. When the switching power supply 13 is used as the power supply of the AC bias type magnetic recording apparatus, the oscillation output of the switching power supply 13 is coupled to the bias oscillator 143 via the photocoupler 142 to synchronize the bias output with the bias oscillator 143. The oscillation frequency and the switching frequency of the switching power supply 13 are set to be the same, and the switching frequency trap and the bias trap are shared.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording apparatus such as a high-speed cassette printer which makes many copies at once, and more particularly, a switching power source is used as a power source in order to reduce the size and weight of the apparatus and make it a worldwide power source. The present invention relates to a magnetic recording device.

[0002]

2. Description of the Related Art In a magnetic recording device (audio duplicator) such as a high-speed cassette printer which makes many copies at one time, a switching power supply is used for the power supply device to reduce the size and weight of the entire magnetic recording device. It also enables worldwide power supply. This is strongly desired not only in the planned production of the magnetic recording device but also in flexibly responding to the change of the destination after the manufacturing. In the past, the above-mentioned demand was realized by using the switching power supply. I am making it happen.

[0003]

By the way, in the conventional magnetic recording apparatus, when a switching power supply is used as the power supply, interference occurs between the switching frequency and the recording bias frequency, and the beat component generated by this is trapped. There is a problem that a circuit must be added and removed. Also, in high-speed printers that copy at 8x speed, the switching frequency is recorded as it is through the head and circuit, which causes unexpected troubles such as noise level, and it is necessary to take measures such as adding a trap circuit. I was there.

The present invention has been made in view of the above points, and provides a magnetic recording apparatus which does not require a special noise countermeasure by making the recording bias frequency and the switching frequency of the switching power supply the same. The purpose is to

[0005]

In order to achieve the above object, the present invention as set forth in claim 1, is a magnetic head for recording a signal on a magnetic medium, and amplifies the signal to drive the magnetic head. A magnetic recording device comprising an amplifier, a bias oscillator that supplies an AC bias current to the magnetic head, and a switching power supply that supplies a control power supply voltage to each circuit, wherein the oscillation frequency of the bias oscillator and the switching power supply are The switching frequency was the same.

According to a second aspect of the present invention, the bias oscillator is oscillated in synchronization with the oscillation of the switching power supply. Further, the invention of claim 3 is configured such that the oscillation output of the switching power supply is supplied to the bias power supply through the withstand voltage signal transmission means.

[0007]

In the present invention, the noise removal trap corresponding to the switching frequency can be shared with the bias frequency trap by making the oscillation frequency of the bias oscillator and the switching frequency of the switching power supply the same.
Further, in the present invention, by causing the bias oscillator to oscillate in synchronization with the oscillation output of the switching power supply, beat noise due to mutual interference between both frequencies can be eliminated.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram showing an example in which the AC bias type magnetic recording apparatus of the present invention is applied to a cassette printer capable of making a plurality of copies at once. In FIG. 1, 10
Is a reproducing section for reproducing the original tape 11. To the reproducing section 10, a plurality of recording sections 12 _{1 to} 12 _n for copying a plurality of original tapes 11 at a time are connected in parallel. Reference numeral 13 is a switching power supply for the magnetic recording apparatus, and 14 is an AC bias generator that operates in synchronization with a signal output from the switching oscillator of the switching power supply 13.

The reproducing section 10 uses an original tape 11
Playback head 1 for picking up signals recorded on
01, a head amplifier 102 and a reproduction equalization circuit 103 connected to the reproducing head 101, and a head amplifier 102.
Of the buffer amplifier 10 connected to the output side of the playback amplifier 105 via the level adjuster 104, and the playback amplifier 105.
A reproduction level meter 107 connected via 6 is provided.
The recording units 12 _{1 to} 12 _n include a level adjuster 121 that adjusts the recording level of the reproduction signal output from the reproduction amplifier 105, a recording amplifier 122 that amplifies the level-adjusted signal, and the recording amplifier 122. A bias trap 123 composed of L and C connected to the output terminal, a recording head 124 connected to the recording amplifier 122 via the bias trap 123, and a bias adjusting circuit 125 connected to the recording head 124 are provided.

The bias generator 14 transmits the output signal of the buffer amplifier 141 and the buffer amplifier 141, which amplifies the oscillation signal output from the switching oscillator (not shown) of the switching power supply 13, to the subsequent stage, and the switching power supply 13 as well. Side, and a photocoupler 142 for ensuring a sufficient withstand voltage, and this photocoupler 1
Bias oscillator 143 that oscillates a high-frequency bias signal in synchronization with the switching oscillation signal obtained through 42.
A recording trigger circuit 144 for giving an oscillation command to the bias oscillator 143, a level adjuster 145 for adjusting the output level of the bias oscillator 143, and a buffer amplifier 146 connected to the subsequent stage of the level adjuster 145. The high frequency current for recording bias output from 146 is supplied to the bias adjusting circuit 125 of the recording units 12 _{1 to} 12 _n . The switching power supply 1
The input side of 3 is connected to a commercial power supply 16 via a power switch 15. In addition, the DC output output from the DC output terminal 13a of the switching power supply 13 is supplied to the reproducing unit 10, the recording units 12 _{1 to} 12 _{n, and the} like.

Next, the operation of this embodiment configured as described above will be described. In FIG. 1, the power switch 1
When the switching power supply 5 is turned on, the switching power supply 13 operates, and the direct current output from the output terminal 13a thereof is supplied to the regeneration unit 1.
0, the recording units 12 _{1 to} 12 _n and the bias generating unit 14 are supplied to the respective circuits and the like to activate these circuits and the like. At the same time, the oscillation signal output from the switching oscillator of the switching power supply 13 is supplied to the bias oscillator 143 through the buffer amplifier 141 and the photocoupler 142. When the trigger switch 144a of the recording trigger circuit 144 is pushed, the bias oscillator 143 oscillates at the same frequency as the switching frequency of the switching power supply 13 according to the oscillation command output from the recording trigger circuit 144. The high-frequency oscillation signal is adjusted to a predetermined level by the level adjuster 145, and then converted by the buffer amplifier 146 into an AC bias current for recording. This AC bias current is applied to each recording unit 12 _{1 to} 12
Recording head 124 through _n bias adjusting circuit 125
Is supplied to. At this time, since the frequency of the AC bias is blocked by L and C of the bias trap 123, the high frequency bias current does not flow into the recording amplifier 122.

On the other hand, in the reproducing section 10, the reproducing head 1
The audio signal picked up from the original tape 11 by 01 is applied to the head amplifier 102 and the reproduction equalization circuit 10.
After passing 3, the level is adjusted by the level adjuster 104, and the power is further amplified by the reproduction amplifier 105, so that each recording unit 1
It is output to 2 _{1 to} 12 _n . In each of the recording units 12 _{1 to} 12 _n , the input audio signal is adjusted to a predetermined level by the recording level adjuster 121, and then amplified by the recording amplifier 122,
Further, after passing through a recording equalization circuit (not shown), the audio signal is applied to the recording head 124 through the bias trap 123 so as to be superimposed on the recording AC bias supplied to the recording head 124 through the bias adjusting circuit 125. The same audio signal is simultaneously recorded on the copy tapes 20 of the respective recording units 12 _{1 to} 12 _n .

As described above, in this embodiment, when the switching power supply 13 is used as the power supply of the AC bias type magnetic recording apparatus, the oscillation output of the switching power supply 13 is coupled to the bias oscillator 143 via the photo coupler 142.
Since the oscillation frequency of the bias oscillator 143 and the switching frequency of the switching power supply 13 are made to be the same by synchronizing, the trap for the switching frequency and the bias trap can be shared, and the noise removing trap corresponding to the switching frequency is not required. The device design and manufacturing can be simplified. Also, the bias oscillator 143
By synchronizing the oscillating frequency and the switching frequency of the switching power supply 13 so as to synchronize with each other, mutual interference between the two frequencies is eliminated and beat noise can be eliminated.

In the above embodiment, the case where the audio signal is copied from one original tape to a plurality of copy tapes at a time has been described. However, the present invention is not limited to this, and the case of one-to-one or the recording head. It is also applicable when there are multiple tracks. Further, the means for synchronizing the oscillation of the switching power supply and the oscillation of the bias oscillator are not limited to the photocoupler shown in the above embodiment, an insulating transformer may be used, and a secondary winding of the switching power supply may be used. Good. Further, the bias oscillator may be independently configured by a ceramic oscillator, a crystal oscillator, or the like.

[0015]

As described above, according to the present invention, a magnetic head for recording a signal on a magnetic medium, an amplifier for amplifying the signal and driving the magnetic head, and an AC bias for the magnetic head. A magnetic recording device comprising a bias oscillator that supplies a current and a switching power supply that supplies a control power supply voltage to each circuit, and since the oscillation frequency of the bias oscillator and the switching frequency of the switching power supply are the same, The switching frequency trap and the bias trap can be shared, and the noise removal trap corresponding to the switching frequency is not required, which simplifies the design and manufacturing of the device. Further, in the present invention, by causing the bias oscillator to oscillate in synchronization with the oscillation of the switching power supply, mutual interference between both frequencies is eliminated and beat noise can be eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic recording device according to an embodiment of the present invention.

[Explanation of symbols]

10 playback unit 11 original tape 12 _{1 to} 12 _n recording unit 13 switching power supply 14 bias generation unit 122 recording amplifier (amplifier) 123 bias trap 124 recording head (magnetic head) 125 bias adjustment circuit 142 photocoupler 143 bias oscillator

Claims (3)

[Claims] 1. A magnetic head for recording a signal on a magnetic medium, an amplifier for amplifying the signal and driving the magnetic head, a bias oscillator for supplying an AC bias current to the magnetic head, and each circuit. A magnetic recording device comprising a switching power supply for supplying a control power supply voltage, wherein the oscillation frequency of the bias oscillator and the switching frequency of the switching power supply are the same. 2. The magnetic recording apparatus according to claim 1, wherein the bias oscillator is oscillated in synchronization with the oscillation of the switching power supply. 3. The magnetic recording apparatus according to claim 2, wherein the oscillation output of the switching power supply is supplied to the bias power supply via an insulation voltage signal transmitting means.