JPH02123501A - Electric power supplying device for rotary head drum - Google Patents

Abstract

PURPOSE:To improve S/N without being accompanied with the rise of the significant manufacturing cost by providing a head amplifier in a rotary drum, and executing the power source supply to a signal type circuit through a rotary transformer for transmitting an erasing signal. CONSTITUTION:Head amplifiers 15 and 15' to directly amplify a micro signal reproduced by magnetic heads 13 and 13' are provided in a rotary head drum. Thus, the S/N can be improved. At that time of supplying the power source to a signal type circuit 3 at a rotary drum side including the amplifiers 15 and 15', an alternating current signal from oscillators 10 and 11 of a fixed side circuit 2 is made into a direct current by a rectification smoothing circuit 20 and supplied to respective parts after transmission by using a rotary transformer 5 for transmitting an erasing signal to an erasing head 17. Thus, the existing constitution is sufficient and the significant rise of the product is not caused. The stable signal transmission by the non-contact rotary transformer 5 can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION A device for supplying power to a rotating head drum according to the present invention will be described in accordance with the following items.

A. Industrial field of application B1 Overview of the invention C1 Prior art [Fig. 2] D0 Problems to be solved by the invention 51 Means for solving the problems F. Embodiment [Fig. 1] 81 Circuit a-1, Fixed side circuit a-21 Rotating drum side circuit 1 circuit operation b-1, during playback b-2, during recording C8 action G0 Effects of the invention (A, industrial application field) The present invention is a novel rotating head This invention relates to a power supply device to a drum. Specifically, it is possible to improve the S/N ratio by providing a signal circuit including a preamplifier for playback in the rotating rad tram, and the power supply to this signal circuit can be supplied to the erase head using the flying erase method. To enable stable power to be supplied to a signal system circuit in a rotary head drum without causing a significant increase in product cost by making it possible to perform this by using a rotary transformer provided for transmission of an erasure signal. It is an object of the present invention to provide a novel power supply device for a rotating head drum.

(B. Summary of the Invention) The power supply device for a rotating head drum of the present invention is a rotating head drum equipped with a signal system circuit including an amplifier for amplifying signals from a magnetic head, an erasing head, and a rotary transformer for signal transmission. This power supply device includes a signal generation source for a power supply that sends an AC signal into the rotating head drum via a rotary transformer for transmitting an erase signal during playback, and a signal generation source for converting the AC signal from the signal generation source into DC. By providing a DC conversion means to supply power to the signal circuit,
It is possible to obtain a reproduced signal with a high S/N ratio without a significant increase in product cost, and also to stabilize the power supply to the signal circuit including this amplifier. .

(C, Prior Art) [Figure 2] Generally, a helical scanning method is used in VTRs, etc., in which the magnetic tape is run in a spiral around the rotation axis of a rotating drum and fixed to a head bar or rotating drum. Signals are recorded and reproduced by a magnetic head that rotates together with these magnetic heads.

FIG. 2 shows an example of a head switching circuit a in a conventional signal recording/reproducing circuit.

b and b' are magnetic heads, and C is a so-called flying erase erasing head that erases signals recorded on a magnetic tape by helical scanning along the recording direction. It is provided on the rotating drum side and connected to a stationary side circuit via a rotary transformer d, thereby inputting and outputting signals.

That is, the magnetic heads b and b'' are connected to their corresponding changeover switches e1e' through rotary transformers d, and in the playback mode, these switches e and e' are switched to the playback side, and each magnetic head b , b' are sent to the preamplifiers f, f', and the preamplifiers f,
The signal amplified by f' is sent to a reproducing amplifier h via a switcher circuit g which switches in synchronization with the head switching signal.

Also, during recording, the changeover switches e and e'' are switched to the recording side, and recording signals for each channel are sent from the recording amplifier i via the switcher circuit j, and these are sent to the rotary transformer d and the magnetic heads b and b. ” and then recorded on magnetic tape.

Further, the erasing head C is connected to an amplifier stand connected to an oscillator k via a rotary transformer d, and the oscillator k or 67M is controlled by a control circuit m.
An erase signal H2 is generated and sent to the erase head C via an amplifier L and a rotary transformer d.

(D. Problem to be Solved by the Invention) However, in the circuit a as described above, the magnetic head b
Since the signal from %b' is sent to the preamplifiers f and f'' via the rotary transformer d, there is a problem that the S/N ratio of the reproduced signal is poor.

Therefore, it is conceivable to provide the preamplifiers f, f' within the rotating drum and to supply power to the preamplifiers f, f'' using a slip ring instead of the rotary transformer.

However, since slip rings are expensive, this inevitably leads to an increase in product costs, as well as the generation of sliding noise as the slip rings rotate, and changes over time due to friction that cannot be ignored, which can shorten the product's lifespan. There are also problems and difficult practical problems.

(E. Means for Solving the Problems) Therefore, in order to solve the above-mentioned problems, the present invention provides a signal system circuit including an amplifier for amplifying the signal from the magnetic head, an erasing head, and a rotary system for signal transmission. A power supply device for a rotary head drum equipped with a transformer, comprising: a signal generation source for a power source that sends an AC signal into the rotary head drum through a rotary transformer for transmitting an erase signal during playback; and a signal generation source from the signal generation source. The system is equipped with a DC conversion means for converting the AC signal into DC signal and supplying power to the signal system circuit.

Therefore, according to the present invention, not only the S/N ratio is improved by the amplifier provided in the rotating drum, but also the power supply to the signal circuit including the amplifier is eliminated via the rotary transformer for signal transmission. Because it is done in a contact manner,
There is no significant increase in product cost, and there is no anxiety associated with contact-type connection means such as slip rings.

(F. Embodiment) [FIG. 1] Details of the power supply device for the rotary head drum of the present invention will be described below according to the illustrated embodiment.

(a, Circuit) Figure 1 shows a circuit 1 of a power supply device to a rotating head drum, which is provided in the rotating drum together with a fixed side circuit 2, two magnetic heads for recording/reproducing, and an erasing head. It consists of a circuit 3. In the drawings, in order to clearly distinguish between the signal line and the power supply line, the signal line is represented by a thin line, and the power supply line is represented by a thick dashed-dotted line.

(a-1, fixed side circuit) 4.4' is a changeover switch, and rotary transformer 5
are connected to the stator side coils 5a and 5b, respectively.
A signal from the mode control circuit 6 connects the coils 5a and 5b to each input terminal of the reproduction amplifier 7 and 7' during playback, and connects the stator side coils 5a and 5b of the rotary transformer 5 to the recording side switcher which will be described later. −
It is designed to be connected to the input terminal of the circuit.

8 is a switcher circuit on the playback side, its two input terminals are connected to the output terminals of the playback amplifier 7. (Switching) It is provided to alternately switch and output the outputs of the two magnetic heads using a gate pulse. and,
The output signal of the switcher circuit 8 is sent to a signal processing circuit (not shown).

Reference numeral 9 denotes a switcher circuit on the recording side, which switches the recording signal sent from the signal processing circuit at a predetermined timing during recording, and switches the recording signal sent from the signal processing circuit at a predetermined timing to the rotary switch via the changeover switch 4.4' set to the recording side by the mode control circuit 6. It is provided to send to the stator side coils 5a and 5b of the transformer 5.

10.11 is an oscillator, and oscillator 10 is 7
The oscillator 11 is provided to generate a 10 MHz erase signal, and the oscillator 11 is provided to generate a 10 MHz power supply signal.
2 is switched, and the signal selected thereby is sent to the stator side coil 5c of the rotary transformer 5.

(a-2, circuit on the rotating drum side) 13.13' is a magnetic head for recording and reproduction, and each magnetic head 13.13' is individually connected to a changeover switch 14.14'.

15. 15' is a head amplifier, and a selector switch 14
．． When 14' is switched to the reproduction side by a signal from a discriminating circuit to be described later, the receivers receive signals from magnetic heads 13 and 13' and amplify the signals, respectively.

16.16' is a changeover switch placed after the head amplifier 15.15';
Similarly to 4', it is switched by a signal from a discrimination circuit to be described later, and when switched to the reproduction side, the output signals of the head amplifiers 15 and 15' are connected to the rotor side coils 5a and 5b' of the rotary transformer 5, respectively. has been done.

Further, when the changeover switches 16.16' and 14.14' are both switched to the recording side, the recording signal from the fixed side circuit 2 is sent via the rotary transformer 5, and this recording signal is sent to the recording side switcher circuit. 9 are sent to the magnetic fields 13 and 13' at a predetermined timing, respectively.
recorded on magnetic tape. In addition, rotary transformer 5
The rotor side coils 5a' and 5b' are coils arranged corresponding to the stator side coils 5a and 5b, respectively.

Reference numeral 17 denotes an erasing head, which, like the magnetic heads 13 and 13', erases along the recording track as the rotating drum rotates, thereby erasing blank areas that tend to occur when using a fixed head for erasing. It is possible to erase images without noise bars, noise bars, etc. The erasing head 17 is connected to the rotor side coil 5c' of the rotary transformer 5 via the switch element 18, and the erasing signal from the oscillator 10 selected by switching the changeover switch 12 is transmitted to the stator side of the rotary transformer 5. It is designed to be sent via the coil 5c and the rotor side coil 5c'.

Reference numeral 19 denotes a discrimination circuit, the input terminal of which is connected to the rotor side coil 5c' of the rotary transformer 5, for distinguishing between AC signals of different frequencies sent from the oscillator 10 or 11 via the rotary transformer 5. This circuit has a filter for determining whether the current mode is a recording mode or a reproduction mode. Then, the discrimination circuit 1
The above-mentioned changeover switch 14.14' is activated by the signal from 9.
and 16, 16' are controlled, and the opening/closing operation of the switch element 18 is also controlled.

20 is a rectifying and smoothing circuit whose input terminal is connected to the rotor side coil 5c' of the rotary transformer 5, which rectifies and smoothes the AC signal sent from the oscillator 10 or 11 to convert it into DC voltage. Head amplifier 15.15' selector switch 14.14' and 16.16
', is provided for supplying the switch element 18 as a power supply voltage. Note that if this rectifying and smoothing circuit 20 is provided with a relatively large capacity capacitor or secondary battery that is charged during playback, the erasing signal to the erasing head 17 will be affected due to the timing difference between the erasing signal and the recording signal. Even when no transmission is performed, supply of power supply voltage to the changeover switch and the like can be ensured.

(b. Circuit Operation) Next, the circuit operation of the power supply device 1 to the rotary head drum will be explained separately during reproduction and recording.

(b-1, during regeneration) In the fixed side circuit 2, the changeover switch 4.4' is switched to the regeneration side by the signal sent from the mode control circuit 6 to the changeover switch 4.4', so the stator side coil of the rotary transformer 5 5a and 5b are playback amplifiers 7
．． The oscillator 11 is connected to the input terminal of the mode control circuit 7' and is selected by a signal sent from the mode control circuit 6 to the changeover switch 12.

Therefore, the 1 0 MH2 AC signal generated by the oscillator 11 is transmitted to the coils 5c and 5c' of the rotary transformer 5.
The current is sent to the rectifying and smoothing circuit 20 via the converter, where it is converted to direct current, and is then connected to the head amplifier 15.15' and the selector switch 14.14.
16.16' and is supplied as the power supply voltage of the switch element 18.

At the same time, since the frequency signal from the oscillator 11 is inputted to the discrimination circuit 19, the discrimination circuit 19 determines that it is the playback mode and switches the selector switch 14.14.
' and 16. Switch 16' to the playback side. Therefore, magnetic head 13 (13') - changeover switch 14 (14')
-Head amplifier 15 (15') → selector switch 16 (1
6') → rotor side coil 5a' of rotary transformer 5
(5b') is formed, by which the recorded signal on the magnetic tape is read out, and the rotary transformer 5
The signal is sent to the reproduction amplifier 7.7' via. The output signal of the reproducing amplifier 7,7' is sent to the reproducing side switcher circuit 8, where the signal is switched by the RF-3W pulse, and a continuous reproduced output is obtained.

Also, since the switch element 18 is opened by the signal from the discrimination circuit 19 to the switch element 18, the oscillator 11
No signal is sent to the eraser rad 17.

(b-2, during recording) In the fixed side circuit 2, the changeover switch 4 is activated by a signal from the mode control circuit 6 to the changeover switch 4.4'.
．． 4' is switched to the recording side, and the recording signal sent from the recording circuit including a modulation circuit (not shown) is extracted field by field by the recording side switcher circuit 9 and distributed to the coils 5a and 5b of the rotary transformer 5. will be sent.

In addition, since the changeover switch 12 is switched to the oscillator 10 side by the mode control circuit 6, the 7MH2
An erase signal is sent to the coil 5c.

Therefore, the discrimination circuit 19 judges from this signal that it is the recording mode, and selects the changeover switches 14, 14' and 16, and IS'.
As a result, recording signals sent from the recording side switcher circuit 9 via the rotary transformer 5 are transmitted to the magnetic healds 13 and 13', respectively. Then, the discrimination circuit 19 closes the switch element 18 and sends the 7MH2 erase signal from the oscillator 10 to the erase head 17.

As a result, after erasing the signal recorded on the magnetic tape, a predetermined recording signal is written and polished by the 6m magnetic pad 13, 13'.

A part of the erase signal is sent to the changeover switches 14, 14' and 15, 15' and the switch element 18 by the rectifier and smoothing circuit 2o.
However, when erasing is not performed, the backup capacitor or secondary battery provided in the rectifying and smoothing circuit 20 is used to supply power to each part as described above.

(c. Effect) Therefore, in the power supply device 1 to the rotating head drum, since the head amplifier 15, 15' that directly amplifies the minute signal reproduced by the magnetic head 13, 13' is provided in the rotating drum, S In addition, when supplying power to the circuit 3 on the rotating drum side including this head amplifier 15, 15', the AC signal from the oscillator 10, 11 of the fixed side circuit 2 is erased from the head 17. Since the power supply voltage is supplied to each part by using a rotary transformer for transmitting the erase signal to and then converting it to DC, the existing configuration can be used without causing a significant increase in product cost. Stable signal transmission is ensured by the contact rotary transformer 5.

(G. Effects of the Invention) As is clear from the above description, the power supply device for the rotating head drum of the present invention includes a signal system circuit including an amplifier that amplifies the signal from the magnetic head, an erase head, and a signal system circuit. A power supply device for a rotary head drum equipped with a rotary transformer for transmission, the device comprising: a signal generation source for a power supply that sends an AC signal into the rotary head drum via a rotary transformer for transmitting an erase signal during playback; The present invention is characterized in that a DC conversion means is provided for converting an AC signal from a signal generation source into a DC signal and supplying power to a signal system circuit.

Therefore, according to the present invention, not only the S/N ratio is improved by the amplifier provided in the rotating drum, but also the power supply to the signal circuit including the amplifier is eliminated via the rotary transformer for signal transmission. Because it is done in a contact manner,
There is no significant increase in product cost, and there is no anxiety associated with contact-type connection means such as slip rings.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of an implementation of a power supply device for a rotating head drum according to the present invention, and FIG. 2 is a block diagram showing an example of a conventional recording/reproducing circuit. Explanation of symbols 1... Rotating head 3... Signal system circuit, 5... Rotary transformer, 11... Signal generation source for power supply, 13.13'... Magnetic head, 15.15'. ... Amplifier, 17... Erasing head, 20... Power supply device to the DC conversion means drum,

Claims (1)

[Claims] A power supply device for a rotating head drum, comprising a signal system circuit including an amplifier for amplifying signals from a magnetic head, an erasing head, and a rotary transformer for signal transmission,
A signal generation source for the power supply that sends an AC signal into the rotating head drum via a rotary transformer for transmitting erasure signals during playback, and converts the AC signal from the signal generation source into DC to supply power to the signal system circuit. A power supply device for a rotating head drum, characterized in that it is equipped with a DC conversion means.