JPS623401A - Rotary head type magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute the pure electrical recording-reproducing changing-over by providing a change-over control circuit to generate a change-over command signal through a rotary transformer at a rotating part in the rotary head where a reproducing amplifier and a change-over switch to change over the recording and reproducing at the rotating part. CONSTITUTION:A recording signal 12 is supplied through rotary transformers 3a and 3b provided at a rotating part 9 to heads 1a and 1b, also supplied to a change-over control circuit 13, further, half-wave rectification is executed by a capacitor 15, a diode 16 and resistances 17 and 18, the input is executed to the base of a transistor 19, and charging and discharging are repeated. At such a time, the voltage-dividing ratio of resistances 22 and 23connected to a collector is set, a collector electric potential of a transistor 24 provided at the rear stage is made equal to an electric power source voltage by a resistance 25, a change-over command 14 is enhanced to the high level and transferred to switches 7a-7d as a recording mode. In such a constitution, the relation of an impedance Zi and a head impedance Zh of a circuit 13 is stipulated to ¦Zi¦>>¦Zh¦.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotating helad type magnetic recording/reproducing device, and particularly to recording/reproducing switching in a device having a built-in reproducing amplifier in a rotating part (hereinafter referred to as the rotor side). It is related to the method.

[Conventional technology]

In a conventional rotary head type magnetic recording/reproducing device, such as a VTR, the configuration shown in FIG. 5 is common. This fifth
In the figure, la and lb are recording and reproducing heads, 2a and 2
b is a reproduction amplifier, 3a, 3b are rotary transformers, 4
5a and 5b are recording amplifiers; 6 is a recording signal processing circuit; 7e and 7f are recording and playback selector switches;
10 is a recording/reproducing switching command.

In a VTR with such a configuration, rotating heads la, l
The reproduced signal detected by b is transmitted to the rotary transformer 3
The signal is transmitted from the rotor side 9 to the stationary side of the main body via the signals a and 3b, amplified to a desired amplitude by the reproduction amplifiers 2a and 2b, and supplied to the reproduction signal processing circuit 4.

However, according to this method, since the head detection signal is weak, it is easily affected by the impedance of the transmission path to the reproduction amplifier, noise, etc.

Therefore, ideally, the playback amplifier should be connected immediately after detecting the head.
In other words, it was considered to incorporate it into the rotor side 9. In this case, the power supply to the rotor side 9 becomes a problem.
Regarding this, as shown in Japanese Utility Model Application Laid-Open No. 59-95407, it has been proposed to provide a solar cell on the rotor side and use it as a power source by irradiating light from the outside.

FIG. 4 is a professional diagram of a two-head recording/reproducing system in a home VTR, for example, and this is a diagram showing the rotor side 9.
This is an example in which the above-mentioned solar cell is used to supply power. In the figure, the same reference numerals as in FIG. 5 indicate the same or equivalent parts, 7a, 7b, 7c.

7d is a recording/reproduction selector switch provided on the rotor side 9;
Reference numeral 8 denotes a solar cell for supplying power to the rotor side, and reference numeral 11 denotes a slip ring mechanism, that is, a sliding contact, for transmitting the switching command 10 to the changeover switches 7a to 7d of the rotor 1119. It goes without saying that the transmission of electrical signals by such sliding contact is a method commonly used in applications such as DC motor brushes.

Next, the operation will be explained.

During recording, the switching command 10 becomes "H" level, and the switches 7e and 7f on the stationary side of the main body are connected to the recording side (positions shown in the figure). Further, a switching command 10 is transmitted to the switches 7a to 7d on the rotor side 9 via sliding contacts 11, and each switch is connected to the recording side (the position shown in the figure). Thereby, the recording signal outputted from the recording signal processing circuit 6 is transmitted to the recording amplifier 5a + 5b, the switches 7e, 7f, the rotary transformers 3a, 3b, the switches 7c, 7d, and 7a',
7b and is supplied to the heads la and lb.

On the other hand, during playback, the switching command 10 becomes "L" level, and the switches 7e and 7f on the stationary side of the main body are connected to the playback side (opposite side in the figure). Also, the switch 7 on the rotor side 9
A switching command 10 is transmitted to a to 7d via a sliding contact 11, and each switch is connected to the reproduction side (the opposite side to the figure). As a result, the playback signals detected by the heads la and lb are transferred to the switches 7a, 7bs, playback amplifiers 2al, 2b.
% switch 7c, 7ds low cry! transformer 3a, 33
b, the playback signal processing circuit 4 through the switches 1e and '7f.
is input.

[Problem that the invention seeks to solve]

As described above, although the method of transmitting switching commands using sliding contacts is common, it does not cause electrical noise caused by sliding, deterioration of signal transmission performance due to wear of the contacts, or complicates the mechanical structure itself. There are problems such as an increase in production costs.

This invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a rotary head type magnetic recording/reproducing device that can perform recording/reproducing switching purely electrically without using sliding contacts. With the goal.

[Means for solving problems]

The rotary head type magnetic recording/reproducing device according to the present invention extracts a recording signal transmitted via a rotary transformer to achieve logic level switching in order to achieve recording/reproduction switching on the rotor side on which the head is mounted. A switching command signal is created.

[Effect]

In this invention, during recording, a recording signal transmitted via a rotary transformer is rectified and converted to a logic level to create a switching command signal.

〔Example〕

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

In FIG. 1, the same symbols as in FIGS. 4 and 5 indicate the same parts, and 13 is the rotary transformer 3a (or 3
b) is a switching control circuit that detects the recording signal 12 transmitted via the switch and generates the switching command 14.

Next, the operation will be explained.

FIG. 2 shows an example of the configuration of the switching control circuit 13 shown in FIG. 1, and FIG. 3 shows signal waveforms of various parts during recording.

When recording, the rotary transformer 3a (or 3
A recording signal 12 of, for example, several VpI) is input to the switching control circuit 13 via b). Incidentally, this recording signal 12 is, of course, a herad la.

1b is also supplied. Recording signal 12 shown in FIG. 3(a)
As shown in FIG. 2, capacitor 15. Diode 16. The signal is half-wave rectified by resistors 17 and 18 and input to the base of transistor 19.

As a result, the collector voltage of transistor 19 is increased by resistor 20. Charging by a time constant circuit including a capacitor 21 and the like and discharging by a transistor 19 are repeated, and a waveform as shown in FIG. 3 (bl) is obtained.

At this time, if the voltage division ratio of resistors 22 and 23 is set appropriately,
The transistor 24 maintains the cut-off state, and the collector potential of the transistor 24 becomes equal to the power supply voltage as shown in FIG. level, and the "recording mode" is transmitted to the changeover switches 7a to 7d in FIG.

On the other hand, during reproduction, there is no recording signal 12, and the outputs of the reproduction amplifiers 2a and 2b are one order of magnitude smaller than the recording signal, for example 20.
The voltage becomes 0 mVpp, and the transistor 19 is cut off. As a result, the base of the transistor 24 is connected to the resistor 2.
0,22.23, a higher voltage is applied, the transistor 24 is turned on, and the switching command 14 goes to "L" level (
playback mode).

In this way, switching between recording and reproduction is achieved, but as mentioned above, since the recording signal 12 is also supplied to the head, the input impedance Z of this switching control circuit 13
f is connected in parallel with the head impedance (more precisely, including the impedance of the changeover switch) Zh, and serves as a load for the recording amplifier 5a (or 5b). However, if 1Zil>>1Zhl is satisfied, it is clear that there is no need to consider the increase in the load on the recording amplifier due to the installation of the switching control circuit 13. That is, in the example of FIG. 2, the resistance value of the resistor 17 may be designed to be sufficiently larger than IZhl.

In this embodiment, since the recording signal is detected and the recording/reproduction switching is performed on the rotor side, noise, wear, etc., which were problems with the conventional method using sliding contacts, are avoided. This makes it possible to avoid problems such as increase in manufacturing costs due to complication of mechanical structure.

Although the above embodiment shows an example in which a switching control circuit is configured using two transistors, the present invention only needs to detect a recording signal and convert it to a logic level, and the purpose can be achieved. Of course, any circuit system may be used as long as it can be used.

Further, the changeover switch may be of any type as long as it achieves its function, and in general, a semiconductor switch such as a bipolar or MOS transistor is used in consideration of miniaturization, but a relay may also be used.

Furthermore, although the above-mentioned embodiment shows an example of a VTR, the present invention can be similarly applied to other rotary head type magnetic recording/reproducing devices, such as a rotary head type digital audio tape recorder, etc. It has the effect of

〔Effect of the invention〕

As described above, according to the present invention, since the rotating section is provided with a switching control circuit for detecting a recording signal and switching between recording and reproduction, problems such as noise and wear occur.

Also, it is possible to avoid an increase in manufacturing costs due to a complicated mechanical structure, and there is an effect that an extremely reliable and inexpensive rotary head type magnetic recording/reproducing device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a VTR according to an embodiment of the present invention;
2rM is a diagram showing an example of the configuration of the switching control circuit of the VTR, Figure 3 is a signal waveform diagram of each part during recording, Figure 4 is a block diagram of a conventional device, and Figure 5 is a reproduction amplifier placed on the stationary side of the main unit. 1 is a block diagram of a conventional general device provided. l a, l b---head), 2a, 2b-reproduction amplifier, 3a, 3b--rotary transformer, 7a
~7 d - rotor side changeover switch, 13 - changeover control circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) In a rotary head type magnetic recording/reproducing device having a reproducing amplifier and a changeover switch for switching between recording and reproducing in a rotating part on which the head is mounted, recording is transmitted to the rotating part via a rotary transformer. A rotary head type magnetic recording and reproducing device, comprising a switching control circuit that detects a signal and generates a switching command signal for switching the switching switch. (2) The above switching control circuit has an input impedance Z
If i is the head impedance Zh, |Zi|>
The rotary head type magnetic recording/reproducing device according to claim 1, wherein the rotary head type magnetic recording/reproducing device is set so that >|Zh|.