JPH02312001A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent a video signal from being affected by an audio signal and to obtain a screen without noise by providing another ground wire where the recording current of the FM audio signal is made to flow separately from a chassis where the recording current of the video signal is made to flow. CONSTITUTION:The ground of the head amplifier 12 of an FM audio is connected to the ground of a recording amplifier 3 through the ground wire 21 without dropping it to a shield case 16. Due to that, a ground 18 for soldering of the shield case 16 where the head amplifier 12 for the FM audio signal is set is made to float in an island state and constituted so as to be separated from a ground pattern 20 in the inside of a head amplifier P plate 17. Therefore, since the recording current of the FM audio does not flow to the chassis, it does not have common impedance 6 with the video signal and the change of the recording current of the FM audio does not affect on the video signal. As the result, a VTR having the screen without noise is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus for recording and reproducing FM audio using an FM audio head provided separately from a video head.

2. Description of the Related Art In recent years, magnetic recording and reproducing devices that employ FM audio (hereinafter referred to as hi-fi VTRs) use rotating heads to perform FM modulation of audio signals for recording and reproducing. Compared to audio, it is possible to achieve a much wider band and higher S/N. Among high-fidelity VTRs, the present invention is a high-fidelity VTR that records and plays back FM audio signals using a head separate from the video head.
This relates to the configuration of TR.

With reference to the drawings below, the above-mentioned conventional high-fidelity V
An example of TR will be explained.

3 and 4 are front views of the configuration of a conventional high-fidelity VTR and a head amplifier.

In Fig. 3, l is an audio signal, 2 is a recording audio processing circuit, 3 is a recording amplifier, 4 is a rotary transformer, 5 is an FM audio head, 6 is a chassis impedance, 7 is a video signal, and 8 is a recording video signal processing circuit. circuit,
9 is a recording amplifier, 10 is a rotary transformer, 11 is a video head, and 12 is a head amplifier for FM audio (
) 13 is a reproduction audio processing circuit, 14 is a video head amplifier, and 15 is a reproduction video signal processing circuit.

In Fig. 4, 16 is a shield case, 17 is a head amplifier printed circuit board, 18 is a soldering pattern, and 19 is a head amplifier printed circuit board.
is solder.

The operation of a conventional high-fidelity VTR configured as follows will be described below.

First, an audio signal 1 is suitably processed in an audio signal processing circuit 2, then FM modulated, amplified to the necessary power by a recording amplifier 3, and supplied via a rotary transformer 4 to a rotating FM audio head 5. After passing through the rotary transformer 4, the recording current flows through the chassis impedance 6 and returns to the recording amplifier 3.

On the other hand, the video signal 7 is processed by a video signal processing circuit 8, then FM modulated and amplified to the necessary power by a recording amplifier 9, and then supplied to a rotating video controller 11 via a rotary transformer 10. . After passing through the rotary transformer 1o, the recording current flows through the chassis impedance 6 and returns to the recording amplifier 9.

During playback, the signal played by the FM audio head 5 is passed through the rotary transformer 4 to the head amplifier (H
, A, ) 12 to an appropriate amplitude, and is demodulated by a reproduction audio signal processing circuit 13 to become the original audio signal 1.

On the other hand, the video signal is also transferred to the head amplifier (H,
A, ) 14 amplifies the signal to an appropriate amplitude, and demodulates the reproduced video signal processing circuit 15 to obtain the original video signal 7.

As shown in Figure 4, since head amplifiers handle small signals, they are usually covered with a shield case 16 to prevent external interference.
It is included in the head amplifier printed circuit board (P board) 1
7 is the soldering pattern provided in the green part of the pattern. By applying solder 19 to the part 18, it is connected to the shield case 16, and the ground of the P plate is connected to the shield case 1.
It's set to 6. Shield cases, on the other hand, are usually fixed to a mechanical chassis with a rotating head cylinder to minimize noise effects. Therefore, if both the audio head amplifier and the video signal head amplifier are fixed to the mechanism chassis, the audio recording current will also flow through the chassis, and the video signal recording current will also flow through the chassis, so as shown in Figure 3. As shown, the chassis impedance 6 becomes a common impedance component for both audio and video signals.

Problems to be Solved by the Invention However, when adopting the above configuration, the chassis impedance 6 becomes a common impedance for the video signal and the audio signal, so changes in the recording current for FM audio will affect the recording current for the video signal. The problem was that it appeared as noise on the screen.

In view of the above problems, the present invention raises the ground of the FM audio head amplifier P board from the shield case, and provides a separate ground line for the return line of the recording current, thereby reducing the common impedance with the video signal. However, it is an object of the present invention to provide a high-fidelity VTR with no noise on the screen by eliminating the influence of audio signals on video signals.

Means for Solving the Problems In order to solve the above problems, in the high-fidelity VTR of the present invention, the ground of the FM audio head amplifier P board is raised above the shield case, and a separate ground wire is prepared for the return wire of the recording current. By doing so, the common impedance with the video signal is eliminated and the audio signal is prevented from affecting the video signal.

Function The present invention solves the conventional problem of FM audio by preventing the FM audio recording current from flowing into the chassis and not having a common impedance with the video signal recording current. This makes it possible to suppress noise generated due to the influence of the recording current on the recording current of the video signal.

Embodiment A high-fidelity VTR according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a high-fidelity VTR in an embodiment of the present invention. In Fig. 1, 1 is an audio signal, 2 is a recording audio signal processing circuit, 3 is a recording amplifier, 4 is a rotary transformer, 5 is an FM audio head, 6 is a chassis impedance, 7 is a video signal, and 8 is a recording video signal processing circuit. 9 is a recording amplifier, 10 is a rotary transformer, 11 is a video head, 12 is a head amplifier, 13 is a reproduction audio signal processing circuit, 14 is a head amplifier, 15 is a reproduction video signal processing circuit, and 21 is a ground line.

FIG. 2 is a diagram showing an embodiment of the present invention, in which 16 is a shield case, 17 is a head amplifier printed circuit board (head amplifier P board), 18 is a land for soldering, 19 is a solder, 20
is a ground pattern.

The operation of the high-fidelity VTR configured as follows will be described below. First, FIG. 1 shows the configuration of the present invention. Unlike the conventional configuration, the ground of the FM audio head amplifier is connected to the ground of the recording amplifier 3 through the ground line 21 instead of being dropped into the shield case. are doing. Therefore, since the FM audio recording current does not flow through the chassis, there is no common impedance with the video signal, and changes in the FM audio recording current do not affect the video signal. FIG. 2 is a diagram showing a specific embodiment of the present invention, in which a land 18 for soldering is floated like an island and is separated from a ground pattern 20 inside the head amplifier P board. With this configuration, the head amplifier P board can be attached to the shield case as in the conventional case, and the internal ground can be raised from the shield board and the chassis while maintaining the external shielding effect. You can realize your purpose.

As described above, according to this embodiment, by floating the ground of the FM audio head amplifier above the shield case and chassis, it is possible to provide a high-fidelity VTR that is free from the influence of FM audio on video signals.

Effects of the Invention As described above, the present invention prevents the FM audio recording current from flowing through the chassis by providing a ground line separate from the chassis through which the recording current for the video signal flows, and thereby prevents the recording current from flowing between the video and FM audio. By preventing both recording currents from having a common impedance, the
The unique effect of providing a high-fidelity VTR without the influence of FM audio can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a high-fidelity VTR according to an embodiment of the present invention, Fig. 2 is a perspective view of a head amplifier section showing a specific embodiment of the present invention, and Fig. 3 is a block diagram of a conventional high-fidelity VT.
FIG. 4, a block diagram of R, is a front view of a conventional head amplifier section. 3... Recording amplifier, 4... Rotary transformer, 12... Head amplifier, 21...
...Ground wire, 6...Chassis impedance. Name of agent: Patent attorney Shigetaka Awano and 1 other person No. 21!
! '-L >'-?；'DO111 TOYA

Claims (1)

[Claims] A first recording amplifier that amplifies a video signal, a first rotary transformer that is tangential to the output of the first recording amplifier, and a recording current from the first rotary transformer that passes through the chassis to the first recording an impedance component of the chassis connected to the ground of the amplifier, a second recording amplifier that amplifies the FM audio signal, a second rotary transformer connected to the output of the second recording amplifier, and from the second rotary transformer. A magnetic recording/reproducing device characterized in that a recording current of the second recording amplifier is connected to the ground of the second recording amplifier via a ground line arranged separately from the chassis.