JP2549675Y2 - Magnetic recording / reproducing device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention provides a magnetic recording / reproducing signal from a magnetic tape by mounting a plurality of recording / reproducing magnetic heads, an erasing magnetic head, and a recording / reproducing circuit / power supply circuit on a rotating cylinder. The present invention relates to a magnetic recording / reproducing apparatus for performing amplification and selection on a rotating cylinder side.

[0002]

2. Description of the Related Art In a rotating magnetic head type magnetic recording / reproducing apparatus, there is a technique for transmitting AC power from a stator side to a rotor side via a rotary transformer mounted on a rotating cylinder, and performing rectification and smoothing stabilization on the rotating cylinder side. For example, it is disclosed in JP-A-60-163204 (G11B 5/02).

[0003]

In the circuit configuration disclosed in the above publication, the same voltage is supplied to each circuit mounted on the rotating cylinder at the time of recording and reproduction. Generally, when trying to share the erasing current and the power to each circuit, they interfere with each other because the video signal frequency and the AC power frequency are close,
Generate a beat on the video screen. Also, depending on the frequency of the video signal erased by the flying erase head,
The S / N ratio of the video signal recorded on the tape after erasing may be deteriorated.

[0004]

[Means for Solving the Problems] From the viewpoint of the power supply frequency,
The effect on the video signal is small when it is far from the video frequency, but there is an erasing frequency at which the erasing characteristics are optimal from the viewpoint of the erasing effect. Also, the higher the effective resistance of the erasing head is, the harder the erasing current flows in the higher region. Therefore, in the present invention, the recording / reproducing magnetic head, the erasing magnetic head, and the circuit section related to the recording / reproducing signal are provided on the rotating side of the cylinder, and the circuit section on the rotating side and the circuit section on the stationary side of the cylinder are rotary. In a magnetic recording / reproducing apparatus electromagnetically coupled by a transformer, a power supply unit for the circuit unit is provided, and a power supply frequency supplied to the power supply unit is made different between recording and reproduction.

[0005]

According to the structure of the present invention, an optimum erasing characteristic can be obtained at the time of recording, and a good screen free from interference due to beats can be obtained at the time of reproduction.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit block diagram of the present invention, FIG. 2 is a diagram showing a relationship between a power supply frequency and a recorded signal spectrum, FIG. 3 is a diagram showing a relationship between a power supply frequency and a reproduced signal spectrum, and FIG. It is a figure showing the relation of a ratio.

In FIG. 1, reference numerals 1a and 1b denote standard mode recording / reproducing magnetic heads, 2a and 2b denote long-time mode recording / reproducing magnetic heads, 3a, 3b, 4a and 4b denote recording / reproducing changeover switches, and 5a, 5b and 5b. 6a and 6b are reproduction preamplifiers, 7a and 7b are head changeover switches, 8a and 8b are mode selection switches, 8a is a switch for switching between a standard mode for reproduction and a long time mode, and 8b is a switch for standard mode for recording. This is a switch for switching to the long-time mode. Switches 9a and 9a 'are opened during playback and closed during recording, switches 9b and 9b' are closed during playback and opened during recording, and 10 is a rotary transformer provided with a signal transmission channel 10a and a power / control / erase channel 10b, respectively. Have been.

Reference numeral 11 denotes a stationary reproduction amplifier, 12 denotes a stationary recording amplifier, 13 denotes a reproduction signal output terminal, 14 denotes a recording signal input terminal,
15 is a power supply rectification / smoothing circuit, 16 is a voltage stabilization circuit, 17 is a DC power supply output terminal, 18 is a switching pulse generation circuit,
19 is a control signal demodulation circuit, 20 is a flying erase head
ON / OFF switch, 21 is a flying erase head, 22
Is a driver circuit, 23 is an FM modulator, 24 is a timing pulse generation circuit, 25 is an RF switching pulse input terminal, 26
Is a mode switching input terminal, and 27 is a recording / reproducing switching input terminal. In FIG. 1, arrow A indicates a component mounted on the rotating side of the rotary cylinder, and arrow B indicates a component disposed on the stationary side of the rotary cylinder.

Next, the operation of the present invention will be described. When a playback button (not shown) is operated during playback, a recording / playback switching signal f is input to the terminal 27 and the switch 9
a, 9b, and 9a ', 9b' are set to the state shown in the figure, and the RF reproduced by each recording / reproducing magnetic head 1a, 1b or 2a, 2b.
After the signals are amplified by the reproduction preamplifiers 5a, 5b, 6a, 6b via the recording / reproduction changeover switches 3a, 3b, 4a, 4b, respectively,
Head changeover switches 7a, 7b and mode selection switch 8a
Via the signal transmission channel 10a of the rotary transformer 10
Supplied to the rotary side and transmitted from the rotating side to the stationary side.
After being amplified at 11, it is output from the playback RF output terminal 13.

In recording, when a recording button (not shown) is operated, a recording / reproduction switching signal f is inputted to a terminal 27, switches 9a and 9a 'are closed, and switches 9b and 9b are closed.
b 'is opened. A recording signal is input to the recording signal input terminal 14, and the recording signal is amplified by the recording amplifier 12, then transmitted to the rotation side via the signal transmission channel 10a of the rotary transformer 10, and recorded via the mode selection switch 8b. /
A recording signal is supplied to one of the recording / reproducing magnetic heads 1a, 1b or 2a, 2b via the reproduction changeover switches 3a, 3b or 4a, 4b.

Next, a method for transmitting a power supply and a control signal for switching each switch will be described. When the RF switching pulse a (see FIG. 5A), the standard / long-time recording mode signal, and the recording / reproduction switching signal f are input from the terminals 25, 26, and 27 to the timing pulse generation circuit 24, the timing pulse generation circuit 24 From FIG. 5
Pulse trains as shown in (b) to (e) are output. Then, a signal having a predetermined carrier frequency is generated in the FM modulator 23, and the generated signal is frequency-modulated by these pulse trains. Signals generated in the FM modulator 23 have different carrier frequencies at the time of recording and at the time of reproduction. And these carrier frequencies are shown in FIG.
The frequency is modulated according to the voltage by the pulse train shown in (e). In FIG. 5, the pulse height (voltage V) between the long-time recording mode signal b and the standard recording mode signal c is shown.
Are set to Vp1 and Vp2, respectively, it is possible to determine on the rotation side A. In other words, the modulated wave transmitted to the rotation side A is controlled by the control signal demodulation circuit 19 as shown in FIGS.
The signal is demodulated into a pulse train similar to that of (e), and the long-time recording mode and the standard recording mode are determined based on the pulse height (voltage V).

At the time of reproduction, the DC applied to the FM demodulator 23
If the offset voltage V ₂ is set higher than the offset voltage V ₁ during recording, and the frequency f ₂ (see FIG. 3) higher than the carrier frequency f ₁ during recording (see FIG. 2) is set as the carrier frequency during reproduction, Interference in a signal band having a small reproduction level can be reduced. The recording time is the rotation erased prior to supplying the erase current of the same frequency as the carrier frequency f ₁ to the flying erase head 21 recording operation.

As shown in FIG. 4, the S / N ratio of a signal recorded after erasing may decrease depending on the erasing frequency.
/ N ratio and flying erase head
21 indicates that the effective resistance increases as the frequency increases,
Current hardly flows to 21, and the erasing characteristics deteriorate. The power supply frequency must be set in consideration of this point.
At this time, the carrier frequency is closer to the signal band than in the reproduction, but the recording signal level is higher than the reproduction signal level, so that the interference is extremely small. Further, by changing the power supply carrier frequency between recording and reproduction, it is possible to detect the recording / reproduction mode on the rotation side A.

The modulated wave modulated by the FM modulator 23 by the pulses shown in FIGS.
After being amplified at 22, it is transmitted to the rotation side A via the power / control channel 10 b of the rotary transformer 10. Rotation side A
This modulated wave is supplied to the rectifier / smoothing circuit 15 and the voltage stabilization circuit.
After being shaped into a predetermined voltage at 16, a DC voltage is supplied to each circuit.

The transmitted modulated wave is demodulated into a control signal pulse train by a control signal demodulation circuit 19, and an RF switching pulse g,
A standard / long-time mode switching signal h and a recording / reproducing switching signal i are generated, and the switches 3a, 3b, 4a, 4b, 7a, 7b, 8a, 8b are switched and controlled. Further, at the time of recording, a signal j for switching the switches 9a and 9b is output from the timing pulse generation circuit 18, and the switches 9a and 9b are switched and the switch 2 is switched.
A signal k for controlling 0 is output, the switch 20 is closed,
An erasing current is supplied to the flying erase head 21.

[0016]

According to the structure of the present invention, the power is supplied at the optimum frequency during recording and during reproduction, respectively, so that an optimum erasing characteristic and a reproduction screen without interference are obtained.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of the present invention.

FIG. 2 is a diagram illustrating a relationship between a power supply frequency and a recording signal spectrum during recording according to the present invention;

FIG. 3 is a diagram illustrating a relationship between a power supply frequency and a reproduction signal spectrum at the time of reproduction according to the present invention;

FIG. 4 is a diagram showing the relationship between the erase frequency and the reproduction S / N ratio according to the present invention.

FIG. 5 is a diagram showing waveforms of respective switch switching signals of the present invention.

[Explanation of symbols]

 1a, 1b Recording / reproducing magnetic head 2a, 2b Recording / reproducing magnetic head 15 Power supply rectification / smoothing circuit 16 Voltage stabilization circuit 18 Switching pulse generation circuit 21 Flying erase head 23 FM modulator 24 Timing pulse generation circuit

Claims (1)

(57) [Scope of request for utility model registration] 1. A recording / reproducing magnetic head (1a, 1b, 2
a, 2b), an erasing magnetic head (21), and a circuit section related to a recording / reproducing signal are provided on the rotating side of the cylinder, and the rotating side circuit section and the stationary side circuit section are electromagnetically driven by a rotary transformer (10). A magnetic recording / reproducing apparatus, comprising: a power supply unit for supplying drive power together with a control signal for the circuit unit on the rotation side; and a carrier frequency of a signal supplied by the power supply unit during recording, which is optimal for erasing. A magnetic recording / reproducing apparatus wherein a frequency is set and applied to the erasing head as an erasing current, and a power supply frequency is made different from that during recording during reproduction.