JPH0454562Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a cylinder device for a video tape recorder (VTR).

(b) Conventional technology A VTR uses a plurality of rotating heads to perform recording and reproduction. A rotary transformer is used to transmit recording and reproduction signals. Recently, it has been considered to incorporate a regenerative amplifier switching circuit or the like into a cylinder device equipped with a rotating head. By doing so, it is possible to realize a wide band and low noise of the reproducing circuit, and also to make the rotary transformer for signal transmission smaller and reduce the number of channels.

As such a configuration, for example, JP-A-59-
Publication No. 146407 discloses that an amplification/switching circuit 1, a control signal generator 2, and a DC voltage generator 3 are built into the cylinder device, and a recording/reproducing signal and control signal power are transmitted via a rotary transformer 4. What transmits the signal is shown (see Figure 4).

(c) Problems to be solved by the invention If a reproduction amplifier or the like is built into the cylinder device of the VTR as in the prior art described above, performance can be improved, but the power supply channel and control signal There is a need for channels to transmit the information, and it has been desired to simplify these transmission paths.

(d) Means for solving the problem In the present invention, power is supplied to a cylinder device that has a built-in regenerative amplifier, switching circuit, etc.
This is done by supplying a DC voltage through a slip ring. Furthermore, the polarity of this DC voltage is set to two types, positive polarity and negative polarity, and a control means for detecting a change in polarity is provided inside the cylinder device to control the mode of the cylinder device.

(E) Effect Therefore, the mode control signal can be transmitted to the cylinder device through the power supply channel, so the configuration of the transmission path between the rotating part of the cylinder device and the outside becomes simple.

(f) Examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram showing a first embodiment;
Figure 2 is a circuit block diagram showing the second embodiment;
The figure is a diagram showing the structure of a cylinder device.

In FIG. 3, reference numeral 11 indicates a rotating part of the cylinder device 10, including two rotating heads 12 and 13 (for recording/reproduction), a PG coil 14 for generating a head switching signal, a reproduction preamplifier, a head switching circuit, and a recording/reproducing head switching circuit.
It is equipped with an electronic circuit 15 such as a regeneration switching circuit.

Magnets 17 and 18 for generating head switching signals are provided at predetermined positions facing each other at 180 degrees on the fixed part 16 of the cylinder device. Fixed part 16 and rotating part 11
Between them is a 1-channel rotary transformer 19.
and a slip ring 20 are provided, and a signal,
Used for power transmission.

In FIG. 1, 21 is a first preamplifier corresponding to the rotary head 12, 22 is a second preamplifier corresponding to the rotary head 13, 23 is a changeover switch (analog switch) for making the two head outputs continuous;
24 is a recording amplifier, 25 is a head switching control circuit that creates a head switching signal (controls the switching switch 23) based on the output of the PG coil 14, 26 is a power supply control circuit, and the first and second diodes (D
1) (D2).

The rotary transformer 19 is for signal transmission,
It is connected to the R/P changeover switch 27 on the fixed portion 16 side of the cylinder device 10. 28 is a reproducing circuit of the VTR, 27 is a recording circuit, 30 is a system control circuit, and 31 is a power supply circuit for supplying power to the cylinder device.

The R/P changeover switch 27 and the power supply circuit 31 are controlled by the output of the system control circuit 30. The power supply circuit 31 is controlled to supply a positive DC voltage to the slip ring 20 during reproduction and a negative DC voltage during recording.

During reproduction, the R/P changeover switch 27 selects the P side, and a positive DC voltage is applied to the slip ring 20. Therefore, the first
The diode (D1) turns on and the first preamplifier 2
1. Second preamplifier 22, head switching control circuit 2
5. Power is supplied only to the changeover switch 23.

Therefore, the reproduced signals from each head 12 and 13 are amplified and supplied to the rotary transformer 19 in a continuous state by a changeover switch 23.

The head switching control circuit 25 generates a head switching signal based on the positive and negative polarity pulses from the PG coil 14. It is composed of flip-flops, delay circuits, etc.

During recording, since a negative DC voltage is applied to the slip ring 20, power is supplied only to the recording amplifier 29 via the second diode (D2). Therefore, the recording signal from the recording circuit 29 is sent to the rotary head 12 via the recording amplifier 24.
13, and recording is performed.

In other words, in the embodiment shown in FIG.
6, a control signal for controlling the mode is created.

In the embodiment shown in FIG. 2, a special playback mode is added as a controlled mode.
Components that are the same as in FIG. 1 are given the same reference numerals.
Further, the head switching control circuit 25 is omitted.

40 is a rotary head for special reproduction, and 41 is a corresponding third preamplifier. Reference numeral 42 represents a reproduction head changeover switch (analog switch) for selecting one of the output of the rotary head 13 and the output of the special reproduction rotary head 40, and 43 represents a normally closed R/P changeover switch (read switch). Further, the power supply control circuit 44 is provided with reed switches 45 and 46 for polarity conversion.

In the embodiment shown in FIG. 2, no DC voltage is applied to the slip ring 20 during recording. Therefore, since the first to third preamplifiers 21, 22, and 41 are inactive and the R/P changeover switch 43 is on, the recording signal from the rotary transformer 19 is supplied to the rotary heads 12, 13.

During normal reproduction, a positive DC voltage is applied to the slip ring 20. Therefore, each reed switch 45, 46 selects the H side, and the first to third reed switches 45, 46
Preamplifier 21, 22, 41, changeover switch 2
3. The power supply voltage is applied to the reproduction head changeover switch 42 with the correct polarity.

Further, since an H level control signal is applied to the reproduction head selection switch 42 from the first diode (D1), the rotary head 13 is selected. As a result, the outputs of the rotary heads 12 and 13 are made continuous by the changeover switch 23 and outputted from the rotary transformer 19.

During special reproduction, a negative DC voltage is applied to the slip ring 20. At this time, since the reed switches 45 and 46 both select the L side, the power supply voltage of the correct polarity is still applied to the first to third preamplifiers 21, 22, 41, the changeover switch 23, and the playback head changeover switch 42. Supplied.

Then, since the reproduction head changeover switch 42 is controlled to the L side, the special reproduction rotary head 40 is selected. That is, during special playback, the outputs of the rotary head 12 and the special playback rotary head 40 are made continuous and output.

In addition, the rotary head 13 and the special reproduction rotary head 4
0 is a so-called double azimuth head, and a special playback head 40 is used for still playback and slow playback.

(g) Effects of the invention As described above, according to the invention, since the mode of the cylinder device is controlled by the polarity of the DC voltage for power supply, the configuration of the transmission path is simplified and is practical.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of the first embodiment, FIG. 2 is a circuit block diagram of the second embodiment, FIG. 3 is a diagram showing a cylinder device, and FIG. 4 is a block diagram of a conventional example. 20...Slip ring, 26, 44...Power control circuit.

Claims (1)

[Scope of utility model registration request] The rotary section includes a plurality of rotary heads, a playback amplifier that amplifies the output from the rotary heads, a head changeover switch that selects the output from the plurality of rotary heads, and a recording/playback mode switch within the rotary section. The fixed part side is a cylinder device that transmits recording/reproduction signals via a rotary transformer, and the rotating part has a PG coil and an output from the PG coil. A head switching control circuit that controls the head switching switch based on the recording/reproducing mode, and a DC voltage having a different polarity depending on the recording/reproducing mode is input from the fixed unit side via a slip ring, and the DC voltage is applied to the reproduction amplifier and the head switching control circuit. A cylinder device comprising: a power supply control circuit that supplies a power supply to a head switching control circuit, the power supply control circuit controlling the recording/reproduction switching circuit in accordance with the polarity of the DC voltage.