JP2576108Y2 - Magnetic recording / reproducing device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called amplifier-equipped drum device in which a signal amplifying circuit is mounted in a rotating drum in a magnetic recording / reproducing apparatus such as a video tape recorder (hereinafter referred to as VTR).

[0002]

2. Description of the Related Art FIG. 2 shows a conventional example. In the figure, the upper half is a power transmission system, the lower half is a reproduction signal transmission system, 1 is a high-frequency oscillation source, and the oscillation frequency of the high-frequency oscillation source 1 is higher than the maximum frequency of the video reproduction signal of about 10 MHZ.
For example, 12 MHz is oscillated. Reference numeral 2 denotes a rotary transformer, which includes a stator coil 3a for power transmission and a rotor coil 3b, and a stator coil 4a for reproduction signal transmission and a rotor coil.
4b is wound. 5 is a diode, 6 is a capacitor, and both constitute a rectifier circuit. Reference numeral 7 denotes a magnetic head, 8 denotes a preamplifier circuit for amplifying a reproduction signal, and 9 denotes a memorization circuit provided on a fixed side. The portion indicated by the dashed line is an amplifier circuit board 10 mounted on the rotating drum, and a flexible printed board (FPC) 11 is shown.

In the above-described configuration, the high-frequency power generated by the high-frequency oscillation source 1 is transmitted to the rotating side via the power transmission coils 3a and 3b of the rotary transformer 2 and rectified by the diode 5 and the capacitor 6. , Preamplifier circuit 8
Supply DC power to The signal reproduced by the magnetic head 7 is amplified by the preamplifier circuit 8, and then transmitted to the fixed-side amplifier circuit 9 via the reproduction signal transmission coils 4a and 4b. Note that, in the figure, the arrows schematically show crosstalk of the power frequency.

[0004]

In the signal transmission path described above, crosstalk from the power transmission coil of the power frequency and the FPC to the reproduction signal system and power frequency jump into the magnetic head occur. The crosstalk from the power transmission coil and the FPC of the rotary transformer and the mixing of high-frequency power into the magnetic head have a phase difference of 180 ° with each other when viewed at the input terminal of the fixed-side amplifier circuit. Levels are also different. As a result, the power frequency crosstalk and the power mixed into the magnetic head do not completely cancel each other, and beat interference occurs on the reproduced screen due to interference between the reproduced signal and the power frequency component.

[0005]

A delay circuit and an output level adjusting circuit are provided between a preamplifier circuit mounted on a rotating side of a rotary drum device and a rotor side coil of a rotary transformer. Further, the delay circuit and the output level adjusting circuit are configured to adjust the delay time and the output level to minimize the crosstalk of the power frequency at the input terminal of the fixed-side amplifier circuit.

[0006]

With the above arrangement, the power frequency directly mixed into the magnetic head is delayed by the delay circuit and the output level adjusting circuit, and after its level is adjusted, the power frequency is changed from the rotating side via the signal transmission coil. The crosstalk power transmitted to the fixed side and magnetically leaked from the FPC and the power transmission side coil to the reproduction signal transmission system coil at the input terminal of the amplifier circuit mutually cancels each other, and the power frequency in the reproduction signal is reduced. Act like so.

[0007]

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. In the figure, the same parts as those of the conventional example are denoted by the same reference numerals, and description thereof will be omitted. The present invention differs from the conventional circuit block diagram in that a delay circuit 12 and an output level adjusting circuit 13 are added.

In the figure, a power frequency directly mixed into a magnetic head 7 is amplified by a preamplifier circuit 8 and delayed by a delay circuit 12 in the next stage so that the phase thereof is different by 180 ° from a crosstalk power frequency described later. The output level is adjusted by the output level adjusting circuit 13 to a level equal to the crosstalk level.
The signal is transmitted to the input terminal of the fixed-side amplifier circuit 9 via 4b. At the input end of the amplifier circuit 9, the power transmission coils 3a,
The crosstalk between 3b and the FPC 11 and the mixed power frequency transmitted through the reproduction signal transmission coils 4a and 4b are canceled out, and unnecessary power frequencies included in the reproduction signal are reduced.

[0009]

According to the structure of the present invention, the power frequency component contained in the reproduced signal at the input terminal of the amplifier circuit on the fixed side of the rotary drum device is reduced, so that a good reproduced image can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a circuit block diagram of a conventional example.

[Explanation of symbols]

 2 Rotary transformer 7 Magnetic head 8 Preamplifier circuit 9 Amplifier circuit 12 Delay circuit 13 Output level adjustment circuit

Claims (2)

(57) [Scope of request for utility model registration] 1. A preamplifier circuit for amplifying an output signal from a magnetic head is built in a rotating drum, and power having a frequency higher than the maximum frequency of a reproduction signal is supplied from a fixed side to the rotating side preamplifier circuit via a rotary transformer. A magnetic recording / reproducing apparatus according to claim 1, wherein a delay circuit and an output level adjusting circuit are provided between said preamplifier circuit and said rotary transformer. 2. The delay circuit delays an output signal from the magnetic head so that the phase differs by 180 ° with respect to the power frequency at a fixed-side amplifier circuit input terminal. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the output signal is adjusted to a level equal to the crosstalk level.