JPH03286401A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To reduce the influence of noise at the time of reproducing by outputting a signal from a magnetic head through an amplification circuit. CONSTITUTION:The outputs of the magnetic heads 2a, 2b are amplified by head amplifiers 4a, 4b, and are supplied to a rotary transformer 5. At that time, since the recording signal of a several V level is not inputted to the rotary transformer 25, switch means 38a, 38b are held as they are in a reproducing state. By supplying the outputs of the magnetic heads 2a, 2b to the rotary transformer after amplifying them, the outputs become difficult to receive the influence of a transmission loss and the noise at the rotary transformer 5 and forward, and therefore, S/N ratio can be improved. Namely, it is discriminated whether the magnetic heads 2a, 2b are in the reproducing state of in a recording state by discrimination circuits 3a, 3b according to signal levels generated in the magnetic heads 2a, 2b, and the switch means are changed according to a discriminated result, and at the time of reproducing, the output signals from the magnetic heads 2a, 2b are amplified on a rotary drum by the amplification circuits. Thus, the influence of the noise, etc., to enter the output signals at the rotary drum and forward can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording/reproducing device, and particularly to a magnetic recording device that uses a rotating magnetic head to record information on a magnetic tape and to reproduce the recorded information. /Relating to playback devices.

Conventional technology Rotating head digital audio tape recorder (R
-DAT), a block recording/reproducing system as shown in FIG. 10 has conventionally been used as a two-channel type.

2a and 2b indicate recording/reproducing magnetic heads.

The reproducing magnetic heads 2a and 2b are placed one on top of the rotating drum.
It is arranged at an angle of 80° and is connected to an RF chain circuit 42 via a rotary transformer 41.

The signal obtained by scanning the magnetic tape with the recording/reproducing magnetic heads 2a and 2b is as small as about 40 μV, and this signal is transferred to a rotary transformer 41 (winding ratio 3:5 to 1:2).
The voltage is boosted and input to the RF amplifier circuit 42. Since the signals to be processed are minute, the RF amplifier circuit 42 is strictly shielded, and the connection wire from the drum unit 43 consisting of magnetic spatulas F2a, 2b, rotary transformer 41, etc. to the RF amplifier circuit 42 is also strictly shielded to avoid the influence of noise. The structure was considered to be difficult to receive.

Problems to be Solved by the Invention However, during playback, conventional magnetic recording/reproducing devices transmit the output of the magnetic head to the RF amplifier circuit as a very small output, which makes it easy for noise to enter the signal, and also to reduce the influence of noise. In order to reduce this, strict shielding is required, which leads to problems such as high cost.

The present invention has been made in view of the above points, and an object of the present invention is to provide a magnetic recording/reproducing device that is less affected by noise during reproduction.

Means for Solving the Problems The present invention provides a magnetic reproducing apparatus that records/reproduces information by scanning a magnetic tape with a recording/reproducing magnetic head fixed to a rotating drum. An amplifier circuit that amplifies a reproduction signal from a magnetic head, an identification circuit that identifies whether the magnetic head is in a recording state or a reproduction state according to a signal level generated in the magnetic head, and the state identified by the identification circuit is a reproduction state. A switching means is provided for outputting a signal from the magnetic head through the amplification circuit in the recording state, and for switching to a circuit that does not include the amplification circuit in the recording state.

An identification circuit identifies whether the working magnetic head is in a reproducing state or a recording state according to the signal level generated in the magnetic head, and the switching means is switched according to the identification result of the identification circuit. During reproduction, the output signal from the magnetic head is outputted by an amplifier circuit. Since it is amplified on the rotating drum, the influence of noise etc. that invades the output signal after the rotating drum is reduced.

Example FIG. 1 shows a block diagram of an embodiment of the present invention.

1 indicates a drum unit. drum unit) += 1
The magnetic heads 2a, 2b, identification circuits 3a, 3b, head amplifiers 4a, 4b, head amplifier power supply 8, rotary transformer 5, switch means 38a.

It consists of 38b. The magnetic heads 2a and 2b are recording and reproducing heads that reproduce information recorded on a magnetic tape and record information on the magnetic tape. The rotary transformer 5 is
Recording/playback transformer 6a.

6b, a power supply transformer 7, and a magnetic head 2a.
, 2b are head amplifiers 4a, 4b and switch means 38
Recording/reproducing transformers 6a, 6b via a, 38b
connected to. The switch means 38a, 38b are switched according to identification signals from the identification circuits 3a, 3b.

The identification circuits 3a and 3b distinguish between the reproduction signal level of several hundred mV during reproduction and the recording signal level of several V during recording, and switch means 38 when the reproduction signal level is several hundred mV during reproduction.
a, 38b are connected to the head amplifiers 4a, 4b side, and when the recording signal level is several volts during recording, the switch means 38a, 38b are connected to the side where the circuit configuration is such that the signal does not pass through the head amplifiers 4a, 4b. . The head amplifier power supply 8 is connected to the power supply transformer 7. Head amplifier power supply 8 includes resistor R1 and rectifier diodes D1 to D4.
, smoothing capacitors CI and C2, and a constant voltage IC (integrated circuit) 9, which rectifies and smoothes the signals supplied to the recording magnetic heads 3a and 3b to generate a DC power supply Vc for driving the head amplifiers 4a and 4b. do.

Rotary transformer 5 is connected to RF amplifier 10. R
The F amplifier circuit 10 includes reproduction RF transformers 1, 12, 13.
, a recording RF amplifier 14, 15° 16, a reproduction signal switching means 17, a recording level control means 18, and a high frequency signal amplification amplifier 39 for power supply.

The reproducing RF transformer 1 is connected to the recording/reproducing transformer 6a, amplifies the signal from the recording/reproducing transformer 6a, and supplies the amplified signal to the reproducing signal switching means I7. The reproduction RF transformer 2 is connected to the recording/reproduction transformer 6b, and the recording/reproduction transformer 2 is connected to the recording/reproduction transformer 6b.
The signal from the reproduction transformer 6b is amplified and supplied to the reproduction signal switching means 17.

The reproduction signal switching means 17 is switched by a switching control signal inputted to the terminal 19, and is switched between the reproduction RF amplifier 11 or 12.
Outputs the output signal.

The output of the reproduction signal switching means 17 is supplied to the reproduction RF amplifier 13, amplified by the reproduction RF amplifier 13, and outputted from the reproduction signal output terminal 20.

The output of the recording RF amplifier 14 is connected to the recording/reproducing transformer 6a.
The output of the recording RF amplifier 15 is input to the recording/reproducing transformer 6b. Recording RF amplifier 14.1
The input of 5 is connected to the output of the RF amplifier 16 via the recording level control means 18. The input of the RF amplifier 16 is connected to a terminal 22, and a recording signal is input to the terminal 22.

Further, the recording level control means is connected to the terminal 21 and controls its output level according to a level control signal inputted to the terminal 21. The output of the power supply RF amplifier 39 is connected to the power transformer 7, and the input is connected to the terminal 40. A high frequency signal is input to the terminal, amplified by the RF amplifier 39, and supplied to the power transformer 7.

The RF amplifier circuit IO is housed in a shield case and is configured to be unaffected by external noise.

The magnetic heads 2a, 2b are arranged on a rotating drum 23 as shown in FIG. Magnetic head 2a and magnetic head 2b
are located at positions 180° different from each other.

The magnetic tape 24 is wound around the rotating drum 23 over 90 degrees and runs.

FIG. 6 shows a perspective view of the drum unit 1. The drum unit 1 includes an upper drum 23 that is a rotating drum, a lower drum 26 that is a fixed drum, and a motor 27 for rotating the upper drum 23. The upper drum 23 has a magnetic head 2a.
, 2b are fixed, and an upper drum board 25 for performing various wirings of the magnetic heads 2a, 2b is also fixed.

The magnetic heads 2a, 2b are fixed to the end of the head base 29 with adhesive as shown in FIG.

A head substrate 28 is fixed to the head base 29, and the winding ends of the magnetic heads 2a, 2b are connected to the head substrate 28. Further, a head amplifier 4a is mounted on the head board 28.
, 4b, switch means 38a.

38b1 identification circuits 3a and 3b are installed. The head base 29 is fixed to the upper drum 23 with screws. The head substrate 28 is connected to the upper drum substrate 25. A head amplifier power supply 8 is formed on the upper drum board 25.
The upper drum board 25 is connected to a rotary transformer 5 that electrically couples the upper drum 23 and the lower drum 26.

Next, the operation of the circuit will be explained. First, signal waveform diagrams during recording are shown in FIGS. 2(B) to 2(F).

During recording, the signal was input to the terminal RF, amplified by the RF amplifier 39, and supplied via the RF multiplier signal transformer 7. Second
Lead to the RF double signal power supply 8 as shown in figure (C), rectify it,
The voltage is smoothed and made constant, and then supplied to the head amplifiers 4a and 4b. At this time, the switch means 38a and 38b are switched to the recording state every time a recording signal is input, as shown in FIG. 2(D). Recording is performed at this timing.

During reproduction, reproduction is performed at the timings shown in FIGS. 3(E) to 3(G). The high frequency signal is as shown in Figure 2 (
It is transmitted to the transformer 7 at the timing shown in E),
The transmitted high-frequency signal is rectified, smoothed, and made into a constant voltage by a power supply 8, and is supplied to the head amplifiers 4a and 4b as a DC power supply Vc. The outputs of the magnetic heads 2a and 2b are sent to a head amplifier 4a.

4b and supplied to the rotary transformer 5.

At this time, since the recording signal at a level of several volts is not input to the rotary transformer 25, the switch means 38a, 38
b is kept in the reproduced state.

In this way, the magnetic heads 2a, 2b and the rotary transformer 5
Head amplifiers 4a and 4b are provided between the magnetic head 2 and
By amplifying the outputs of a and 2b and then supplying them to the rotary transformer 5, the outputs after the rotary transformer 5 are less susceptible to transmission loss and noise, making it possible to improve the S/N ratio. Figure 4 shows the frequency characteristics of the magnetic recording/reproducing device configured in the example, and shows the frequency characteristics of the conventional head amplifier 4.
a.

2=3dl'3 compared to those without 4b. C/N(Ca
rry/No.1se) ratio has improved.

In addition, since the input is made to the RF amplifier circuit 10 with a low impedance, the influence of the stray capacitance [IC] of the RF amplifier circuit 10 is reduced, so the frequency characteristics in the high frequency region are improved compared to the conventional one, as shown in Fig. 4. , extends by 20-30%. In addition, since the influence of noise is small, shielding can be simplified and realized at low cost.

In this embodiment, the head amplifiers 4a and 4b are mounted on the head substrate 28, but the present invention is not limited to this, and they may be mounted on the upper drum substrate 25, as long as they are mounted on the rotating drum. However, the one closer to the magnetic heads 2a and 2b is less susceptible to noise.

FIG. 8 shows a block diagram of another embodiment of the present invention.

Components that are the same as those in FIG. 1 are given the same reference numerals, and their explanations will be omitted.

In this embodiment, the rotary transformer 30 is configured as one system. The RF amplifier circuit 31 is a reproduction amplifier 32,3
3. Recording amplifier 34.35, Recording 1 Novel control means 3
6, and both the reproduction system and the recording system are constructed in one system without switching means.

The magnetic heads 2a and 2b form a loop together with a rotary transformer 30, and head amplifiers 4a and 4 are included in this loop.
b and switch means 38a, 38b are inserted. A power supply 8 is connected to both ends of the magnetic heads 2a, 2b, rectifies and smoothes the signal supplied to the magnetic heads, makes it a constant voltage, and supplies it as a power supply Vc to the head amplifiers 4a, 4b. Further, the connection points of the magnetic heads 2a and 2b are connected through a switch means 37, and the switch means 37 is controlled by the identification circuit 32 like the switch means 38a and 38b. The switch means 37 is turned on during reproduction.

The operation will be explained with reference to FIG. As shown in FIG. 9, a high frequency signal for power supply is inputted to the RF amplifier circuit 31 during a period other than the recording or reproduction period, and is passed through the RF amplifier 35, the level control means 36, and the RF amplifier 34 to the rotary transformer 30. is supplied with a high frequency signal.

A high frequency signal supplied during a period other than the recording or reproduction period is rectified, smoothed, and made into a constant voltage by the power supply 8, and is supplied to the head amplifiers 4a, 4b to drive the head amplifiers 4a, 4b.

In this way, by reducing the number of winding channels of the rotary transformer 30 to one, the transmission loss of the rotary transformer can be reduced, and the S/N ratio can be further improved.

Effects of the Invention As described above, according to the present invention, since the output signal of the magnetic head is amplified on the rotating drum and outputted to the outside via the signal output means, the signal processing after the rotating drum is not affected by noise. It has features such as being difficult to use.

7 is a plan view of essential parts of an embodiment of the present invention; FIG. 8 is a block diagram of another embodiment of the present invention; FIG. 9 10 is a diagram for explaining the operation of another embodiment of the present invention, and FIG. 10 is a block diagram of a conventional example.

2a, 2b... Magnetic head, 3a, 3b... Identification circuit, 4a, 4b... Head amplifier, 5... Rotary transformer, 8... Power supply for head amplifier, 23... Upper drum.

Claims (1)

[Scope of Claims] A magnetic recording/reproducing device that records and reproduces information by scanning a magnetic tape with a magnetic head that is fixed to a rotating drum and performs recording and reproduction. an amplifier circuit for amplifying a reproduction signal of the magnetic head; an identification circuit for determining whether the magnetic head is in a recording state or a reproduction state according to a signal level generated in the magnetic head; A magnetic recording/reproducing device characterized by comprising a switching means for outputting a signal from the head through the amplifying circuit and switching the circuit to supply a signal to the magnetic head that does not include the amplifying circuit when in a recording state. Device.