JPS59151306A - Video tape recorder - Google Patents

Abstract

PURPOSE:To realize easily broad band and high S/N for a reproducing amplifying system by applying an output of an erase/bias oscillator to a DC voltage generator via a rotary transformer and activating a signal processing circuit by the DC voltage generator. CONSTITUTION:A DC power supply for the supply of power is obtained by amplifying an output of the erase/bias oscillator 15 at an amplifier 25, feeding the amplified result to a rotary cylinder side through a channel 21 of the rotary transformer 18, making the DC voltage generator 24 at the rotary cylinder side receive it and rectifying and smoothing the received output. Since a rotary head and a signal processing circuit section exist in the rotary cylinder, the distance is very short thereby realizing broad band and the head output is amplified to a sufficient large level, allowing to obtain high S/N. Moreover, in constituting the system that a recording/reproducing signal, a control signal and an output of the erase/bias oscillation for power supply are transmitted by the rotary transformer 18, since the number of the rotary heads is made identical to the transmission channel number of the amplifying and rotary transformers, the miniaturization of the rotary transformer is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION 2. Field of Industrial Use The present invention relates to a rotary head type video tape recorder.

Conventional configurations and their problems In recent years, as the popularity of video tape recorders has increased, significant progress has been made in making them smaller and lighter, increasing their performance, and adding additional functions such as special playback. These factors have limitations in the conventional technology, and new technology is desired.

The same goes for the rotating head part.Recently, in order to perform various special playbacks, to achieve long-term motion with good image quality, and to realize video signal rewriting called video insert, It has become necessary to mount a large number of rotating heads. In this case, the signal softening between the rotating head and the stationary side circuit section is usually done by a rotating transformer, and the number of transmission channels of the rotating transformer corresponding to the number of rotating heads is required. It was difficult to realize this because it had a large shape.

- There is still a demand for a wider band of rotary head reproduction output in terms of performance, and for this purpose it is necessary to place the reproduction throat amplifier as close to the rotary head as possible to reduce stray capacitance. FIG. 1 shows a conventional example of a video tape recorder that records and reproduces video signals with a rotating head and audio signals with a fixed head.

In the figure, reference numerals 1 and 2 are rotary heads for recording and reproducing video signals, which are arranged on the rotary cylinder at an angle of 1800 degrees, and are indicated by a broken line frame 3 as a group of rotary heads. Now, as is well known, the rotary joints 1 and 2 are connected to the stationary circuit through a rotary transformer 4.
The recording/playback head 1.2 is connected to channel 5 of the rotating transformer 4.
. 7) During playback, press the recording/playback selector switch γ~1.
0 is in the connection state shown in the figure, and the outputs of the rotary heads 1 and 2 are passed through channels 6 and 6 of the rotary transformer 4 to the regenerative amplifier 11.
．． After the signal is amplified at step 12, a head output switch 13 selects and outputs the intercostal space (one field) where each head is in contact with the tape. .

During recording, the recording/internal selection switch 7.9 is opened,
8, 10 are closed and the recording signal is supplied via the recording amplifier 14 to the channels 5, 6 of the rotating lance 4, which will cause the recording current to flow through the rotating heads 1 and 2.

The output of the erasing/bias oscillator 16 supplies an erasing current to the erasing fixed head 16 and a high frequency bias current to the audio signal recording/reproducing head 17, respectively. Used for recording signals.

]7 However, in the above configuration, the rotary transformer 4 is usually installed inside the cylinder block, and is used for recording and recording.
The regeneration selector switches 7 to 10, the regenerative amplifiers 11 and 12, and the like are mounted on a printed circuit board together with other circuit blocks. Since the rotating head and the printed circuit board are located apart from each other in steps 1 to 5, a shielded wire is used as a connection line between the rotating transformer 4 and the circuit section, and its capacity reaches several +CPFI:].

Therefore, there was a problem in that the frequency characteristics during playback could not be expanded. In other words, it can be said that it is not suitable for widening the band of the head amplifier.

Unfortunately, the head output cannot be passed through the rotary transformer 4 and then amplified by the regenerative amplifiers 11 and 12, otherwise signal loss will occur in the rotary transformer and the signal level will drop somewhat, degrading the S/N of the reproducing output. The problem is that

Furthermore, in the case of Figure 1, there are two recording/playback heads, but it is possible to add a rotary head to improve the image quality for special playback (slow-motion or fast-forward/rewind playback), or to add a rotary head exclusively for long-time mode. When adding more rotary heads, it is necessary to increase the number of channels in the rotary transformer as the number of heads increases, and the rotary transformer becomes larger, which limits the number of heads that can be used. It had some problems.

Purpose of the Invention The purpose of the present invention is to make it possible to widen the band and increase the S/N of a regenerative amplification system, and to reduce the number of rotary heads that can be attached to the same rotary cylinder by reducing the number of channels of a rotary transformer. It is an object of the present invention to provide a video tape recorder that can easily achieve this without increasing the number of video tapes.

Structure of the Invention The video tape l/gouda converter of the present invention is equipped with an erasing/bias oscillator that supplies signals to a fixed erasing head and an audio fixed head, and a rotary head for recording and reproducing, and a rotary transformer is provided between the rotary head and the rotary transformer. is provided with a signal processing circuit and a DC voltage generator, and is configured to supply the output of the cancellation/bias oscillator to the DC voltage generator via a rotary transformer, and to operate the signal processing circuit by the DC voltage generator. As a result, it is possible to realize a wide band and a high S/1'J of the reproducing amplification system, and the number of rotating heads can be easily increased, thereby improving the reproduced image quality.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 on page 7 is a diagram showing the main circuit configuration of an embodiment of the present invention. In FIG. 2, reference numerals 1 and 2 are rotary heads for recording and reproducing similar to those shown in the conventional example of FIG. Signals are exchanged.

Channel 1 of rotating heads 1 and 2 and rotating transformer 18
A signal processing circuit consisting of an amplification/switching circuit 22 and a control signal generator 23 is inserted between 9 and 20, and the amplifying/switching circuit 22 amplifies the reproduction output of the rotary head 1.2 and alternately switches the output. Channel 19 of rotating transformer 18
Switching control is performed so that the recording signal transmitted from the channel 19 is supplied to the rotary heads 1 and 2. These controls are executed by receiving a control signal transmitted from the channel 2o of the rotary transformer 18 in the control signal generator 23 and converting it into a signal for controlling the amplification/switching circuit 22.

Since the amplification/switching circuit 22 and the control signal generator 23 are inserted between the rotary heads 1 and 2 and the rotary transformer 18, they are provided in a cylinder that rotates together with the rotary heads 1 and 2. As is well known, in a conventional video tape recorder, the rotating cylinder section does not have a power source, so a power source is required to operate the amplification/switching circuit 22 and the control signal generator 23. This power supply is
The output of the bias oscillator 16 is amplified by an amplifier 25, transmitted to the rotating cylinder side through the channel 21 of the rotating transformer 18, and is received by the DC voltage generator 24 on the rotating cylinder side, where it is rectified and smoothed to obtain a DC power source. Configure. The output of the erasing/bias oscillator 15 supplies an erasing current to the erasing head 16, and a high frequency bias is applied to the throat for audio recording, as in the conventional example. The oscillation frequency of the cancellation/bias oscillator 16 is usually selected to be several times the upper limit frequency of the audio signal, and is approximately 60 KH,Z to 120 KHz.

On the other hand, the transmission band of each channel of the rotary transformer 18 is 70
KHz to several MHz. Therefore, the frequency of around 100KH2 generated by the erasure/bias oscillator 16 can be transmitted directly to the rotation side via the rotary transformer 18. 100 KHz is near the lower limit of the transmission band of the rotating transformer, and even if there is crosstalk between the channels of the rotating transformer, the transmission band of the video signal is 100 KHz to 5 M) (z), so the interference to the video signal is The effect is small.Using the oscillation frequency of the erasure/bias oscillator 16 as a medium for power supply to the rotating cylinder side in this way has many advantages.

In this embodiment, since the rotating head and the signal processing circuit are located inside the rotating cylinder, the distance between them is extremely short and does not impede the widening of the band as explained in the conventional example.
Furthermore, a high S/N ratio can be obtained by amplifying the head output to a sufficiently large level before transmitting it through a rotary transformer. Although not shown in the embodiment of FIG. 2, an amplification/switching circuit 22 is provided between the rotary head and the rotary transformer. A control signal generator 23 and a DC voltage generator 24 are arranged,
If the rotating transformer 18 is configured to transmit recording/reproducing signals, control signals, and erase/bias oscillation outputs for power supply, even if the number of rotating heads is increased to 10 pages, the formation of control signals will become complicated. However, since the number of transmission channels of the rotary transformer is the same, even if the rotary cylinder has a multi-head structure, the rotary transformer can be made small.

Effects of the Invention As is clear from the above explanation, the present invention provides a signal processing circuit between the rotary head and the rotary transformer,
A DC voltage generator is provided to obtain a DC voltage from a signal supplied from a bias oscillator via a rotary transformer, and the signal processing circuit and control circuit are operated by this DC voltage. This eliminates the need for a separate oscillator to supply the signal, and therefore not only requires a simple circuit, but also requires attention only to the erasure/bias oscillation frequency in order to prevent beat disturbance to the video signal, as in the past.

In addition to the effect that the rotary transformer can be made smaller than the multi-head rotary cylinder, the present invention also provides the following effects in terms of performance. In other words, since the regenerative amplifier is mounted inside the rotating cylinder, the head and the amplifier can be connected with a very short line.As a result, the stray capacitance on the input side of the amplifier is extremely small, and the signal transmission band can be widened. can be accomplished. In addition, during playback, the weak signals picked up by the head are amplified to an appropriate level before being transmitted via the rotating transformer, so there is almost no S/N deterioration due to transmission loss in the rotating transformer, and the high S
/N can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a main part of a conventional rotary head type video tape recorder, and FIG. 2 is a diagram of a main part circuit diagram of an embodiment of the present invention. 1.2... Rotating head for recording and playback, 16...
・・Erase/bias oscillator, 16 ・・Erase head, 1
7... Audio recording/playback head, 18... Rotating transformer, 22... Amplifying/switching circuit, 23. Control signal generator, 24... DC voltage generator, 25... Amplifier. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure/1 wJ2 diagram

Claims (2)

[Claims] (1) Equipped with an erasing/bias oscillator that supplies signals to a fixed erasing head and an audio fixed head, and a rotating head for recording/reproducing, and a signal processing circuit and a DC voltage generator are installed between the rotating head and the rotating transformer. A video tape recorder, characterized in that the output of the erasure/bias oscillator is supplied to the DC voltage generator via a rotary transformer, and the signal processing circuit is operated by the DC voltage generator. (2) The rotating transformer that transmits signals between the rotating head and the fixed side circuit is configured to include a transmission channel for recording/reproduction signals, a transmission channel for control signals, and a transmission channel for erasing/bias oscillation signals. A videotape recorder according to claim (1).