JPS60239901A - Rotary head cylinder - Google Patents

Abstract

PURPOSE:To make it possible to use many magnetic heads by providing an upper cylinder and a lower cylinder with light receiving and emitting elements to transmit optically signals between internal circuits of the upper cylinder and external circuits and not using a rotary transformer for signal transmission between them. CONSTITUTION:A light receiving and emitting element 9 provided on a rotating upper cylinder 1a faces a still light receiving and emitting element 11 in the side of a lower cylinder 1b through an optical fiber 10 (rotated together with a revolving shaft 4) provided in the center of the revolving shaft 4. Consequently, all recording signals and reproduced signals are transmitted optically, and therefore, the rotary transformer is used only in one channel for power transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rotating head cylinder for a video tape recorder (hereinafter abbreviated as VTR).

[Background of the invention]

FIG. 1 is an exploded perspective view showing a conventional rotary head cylinder used in a helical scan VTR.

In FIG. 1, 1a is an upper cylinder, 1b is a lower cylinder, 2 is a motor, 3ajb is a magnetic head, 4 is a rotating shaft, and 5a and 5b are rotary transformers.

In FIG. 1, the upper half of the cylinder (hereinafter referred to as the upper cylinder) 1a is rotated by a motor 2, and the magnetic heads 5a and 3b attached to the upper cylinder 1a are rotated relative to the magnetic tape (not shown). to record and play back signals.

2(a) is a plan view showing the rotary transformer in FIG. 1, and FIG. 2(b) is a sectional view thereof.

In FIG. 2, 6a to 6C are concentric grooves, and 78 to 7C are windings. Rotary transformers 5a and 5b have concentric cores as shown in FIGS. 1 and 2. Groove 6a provided in.

After inserting the windings 1i7a, 7b, and 7c into 6b and 6C, respectively, the two cores are arranged so that their grooved surfaces face each other and are coaxial with the rotating shaft 4. The rotary transformer 5a is fixed to the upper cylinder 1a and rotates together with the upper cylinder 1a.
The rotary transformer 5b is fixed to the lower cylinder 1b.

FIG. 6 is a circuit diagram for explaining conventional signal transmission. In FIG. 3, 3a is a narrow track even field magnetic head, 3b is a narrow track odd field magnetic head,
Loc is a wide track even field magnetic head, 3d is a wide track odd field magnetic head, 5a and 5b are rotary transformers, 8a, 8b, 8c,
8d are recording/reproducing amplifiers, respectively. Incidentally, the magnetic heads 3a and 3b are LP (Long Play
: The magnetic heads 3c and 3d are used for SP (5 standard playback).
:Standard speed recording/playback).

Conventionally, the recording/reproducing amplifiers 88 to 8d are all arranged outside the rotary head cylinder, and as shown in FIG.
- 8d are all transmitted via rotary transformers 5a and 5b provided coaxially with the rotating shaft 4. In other words, signals can be transmitted through the magnetic head transformers 5a and 5b even when the upper cylinder housing the magnetic head is in a rotating state.

By the way, as shown in FIG. 3, the rotary transformer 5a
, 5b requires the same number of channels as the number of magnetic heads attached to the upper cylinder.

However, this number of channels is limited to the concentric grooves 6 shown in FIG.
As shown in the figure, the number of grooves is limited by the outer diameter of the core of the rotary transformer, that is, the outer diameter of the rotating head cylinder (the rotary transformer is built into the rotating head cylinder). There is a limit to the number of channels a facility can obtain.

However, as VTRs have become more sophisticated in recent years, the number of magnetic heads attached to the upper cylinder has increased to include one pair of heads for narrow tracks, a pair of heads for wide tracks, a pair of heads for PCM audio, and a pair of heads for special playback. A total of 7 to 8 transformers are required, and on the other hand, as VTRs become smaller, the outside diameter of the syringe is shrinking, making it impossible to mount as many as 8 channels of rotary transformers. be.

Therefore, such conventional technology has the disadvantage that the number of magnetic heads, that is, the function of the VTR is limited by the rotary transformer.

Furthermore, in addition to the above, in the conventional technology, as described above, the magnetic heads 3a to 3d and the regenerative amplifiers 83 to 8d
Rotary transformers 5a and 5b are interposed between the two, which is a cause of deterioration of the 8/N ratio of the reproduced signal during reproduction. 4. between the upper cylinder internal circuit and the external circuit, eliminating the drawbacks of the prior art.

An object of the present invention is to provide a rotary head cylinder that can perform signal transmission without using a quadrilateral transformer, and can use a large number of magnetic heads without being limited by the number of channels of a rotary transformer.

[Summary of the Invention 41 To achieve the above object, the present invention uses light for signal transmission between the upper cylinder and an external circuit. For this purpose, first, in addition to the magnetic head, the upper cylinder is equipped with a light receiving/emitting element, a modulation/demodulation circuit, and a recording/reproducing amplifier, and the external circuit is also equipped with a light receiving/emitting element.

A modulation/demodulation circuit is provided for each. Since it is preferable that both light emitting and receiving elements are always facing each other, an optical fiber or a hollow portion is provided within the rotation axis of the upper cylinder so as to include the center of rotation, and the light receiving and emitting elements are arranged at both ends of the optical fiber or a hollow portion.

With such a configuration, signal transmission via light is realized between the upper cylinder and the external circuit. In addition, the power necessary to operate the light receiving and emitting elements, the modulation/demodulation circuit, etc. is transmitted at high frequency via the conventionally used rotary transformer.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 4 to 6.

FIG. 4 is a circuit diagram showing the circuit configuration in one embodiment of the present invention.

In this embodiment, each of the magnetic heads 3a to 3d is
Recording/re-switching switch 12a built into the upper cylinder
12d, it is connected to reproducing amplifiers 1+a to 13d and recording amplifiers 14a to 14d, which are also incorporated in the upper cylinder.

As shown in FIG. 4, each output of the regenerative amplifiers 13a to 13d is connected to the modulator 16, and the light emitting element 9b on the upper cylinder side is connected to the modulator 16.
The signal is converted into an optical signal and transmitted to the external circuit 17 via the light receiving element 11b on the lower cylinder side. On the other hand, external circuit 1
The recording signal emitted from 7 is transmitted to the light emitting element 11 on the lower cylinder side.
a, the light is converted into light by the upper cylinder side light receiving element 9a and the demodulation circuit 15, and then sent to the desired recording amplifiers 14a to 14d.
added to.

In addition, DC power for operating the changeover switch, amplifier, etc. on the upper cylinder side is obtained by amplifying a high frequency wave obtained from an oscillator 18 with a power amplifier 19 and transmitting it to the upper cylinder side via a rotary transformer 5. This is obtained by rectifying the high frequency power transmitted to the diode 20. The frequency is a frequency that does not interfere with the video signal (
For example, it is better to select 20MHz or higher).

Further, a switching signal Q that drives the recording/reproducing switches 12a to 12d to switch the switches is generated in the demodulation circuit 15 by a control signal that is generated from the external circuit 17 and transmitted through the same route as the recording signal. . An electronic switch using a diode is suitable for the recording/re-switching switch used here.

FIG. 5(a) is a circuit diagram showing a specific example of the recording/re-switching switch in FIG. 4, and FIG. 5(b) is a timing chart showing a specific example of the control signal for mode switching and the switching signal generated thereby. be.

In Fig. 5, D, Dt are switching diodes, S are control signals, Ql and Ql are recording/playback mode switching signals, and QB and Q4 are L, respectively.
P/S P head switching signal.

As described above, the control signal S1 generated from the external circuit 17 is input to the demodulation circuit 15, where it is converted into the switching signal Ql.

Create Q, , Q, , Q. That is, the fifth
As shown in FIG. (b), for example, when setting the LP recording mode, four pulses are input to the demodulation circuit 15 as the control signal S, so that the demodulation circuit 15
The LP/8P head switching signal Qs becomes H and Q becomes L to select the magnetic head 6a, and the recording/reproduction mode switching signal Q1 becomes H and Q becomes L and the recording/reproduction switch 12aj is input. be done.

Therefore, as shown in FIG. 5(a), for example, the recording/playback mode switching signal Q is set to H (voltage similar to power supply voltage +■).
, Q, are input to the recording/re-selecting switch 12a as L, the switching diode D is in a conductive state due to the forward voltage, and the switching diode D1 is in a non-conducting state because there is no forward voltage. Become. Therefore, the magnetic head 8 for LP.

3a is the switch diode D! It is connected to the recording amplifier 14a via the recording amplifier 14a. Similarly, when Q is H and Q is L, the diode D is conductive and the magnetic head 3 is turned on.
a will be connected to the regenerative amplifier 15a.

In addition, the recording amplifier and reproduction amplifier are shared by each magnetic head by devising a recording/re-switching switch for each.
Figure 6 is an exploded perspective view showing one embodiment of the present invention.

As shown in FIG. 6, the light receiving/emitting element 9 of the rotating upper cylinder 1a (rotating together with the upper cylinder 1a) is connected to an optical fiber 10 (rotating shaft 4) provided at the center of the rotating shaft 4.
rotates with ) is opposed to the light receiving/emitting element 11 (which does not rotate) on the lower cylinder 1b side. Note that although the light receiving/emitting element 9 of the upper cylinder 1a and the optical fiber 10 can be in close contact, it is necessary to leave a gap between the light receiving/emitting element 11 of the lower cylinder 1b and the optical fiber 10 so as not to hinder rotation.

According to this embodiment, since the recording signal and the reproduction signal are all transmitted by light, the rotary transformer only needs to have one channel for power transmission. Since optical transmission has a wide band, a large number of signals can be transmitted simultaneously using one set of light receiving and emitting elements.

By the way, transmitting a large number of signals with one set of transmitting and receiving elements would complicate the circuit configuration, so as a more practical idea, as shown in Figure 7, the recording signal is transmitted as usual with a rotary transformer, and the reproduction One possible method is to transmit only the signal using light.

FIG. 7 is a circuit diagram showing a circuit configuration in another embodiment of the present invention.

In this embodiment, light is used only for transmitting a reproduced signal whose signal power is small and the S/C ratio is likely to be a problem, and a conventional rotary transformer is used for a recording signal that transmits a relatively large power. Note that the recording amplifiers 14a and 14b can also be omitted.

With this configuration, since signal transmission by light is only unidirectional, it is sufficient to provide only the light emitting element 9b in the upper cylinder and the light receiving element 11b in the upper cylinder. Further, in this embodiment, the head selection switches 21a to 21d are used to
By using one recording amplifier or one reproduction amplifier for two magnetic heads, the number of recording amplifiers and reproduction amplifiers can be reduced to two. Therefore, in this case, the rotary transformer may have two channels for signals and one channel for power transmission, which is the number of channels that can be realized with current technology.

Furthermore, in this embodiment, the control signals for each switch are transmitted while being superimposed on the high frequency power supply or the recording signal. Alternatively, sequence control may be used to transmit the recording signal, and the recording/reproducing mode switching signal, the head switching signal, and the recording signal may be sequentially transmitted. Of course, it is also possible to provide a channel dedicated to control signals in the rotary transformer.

〔Effect of the invention〕

As explained above, according to the present invention, all or part of the signal transmitted between the internal circuit and the external circuit can be transmitted without using a rotary transformer. Since a large number of magnetic heads can be used without being limited by the number of channels, a multifunctional VTR can be obtained.

[Brief explanation of drawings]

Figure 1 is an exploded perspective view showing a conventional rotating head cylinder;
FIG. 2(a) is a plan view showing the rotary transformer in FIG. 1, FIG. 2(b) is a sectional view, FIG. 3 is a circuit diagram for explaining conventional signal transmission, and FIG. 4 is a plan view of the rotary transformer according to the present invention. FIG. 5(a) is a circuit diagram showing a specific example of the recording/re-switching switch in FIG. 4, and FIG. 5(b) is a circuit diagram showing the circuit configuration in one embodiment. FIG. 6 is an exploded perspective view showing one embodiment of the present invention, and FIG. 7 is a circuit diagram showing a circuit configuration in another embodiment of the present invention. 1a...upper cylinder, 1b...lower cylinder, 2...
Motor, 3... Magnetic head, 4... Upper cylinder rotating shaft, 5... Rotary transformer, 6... Groove of rotary transformer, 7... Winding, 8... Recording/reproducing amplifier, 9 ...Receiving and emitting element, 10... Optical phino (-111... Receiving and emitting element, 12... Recording/re-switching switch, 13... Reproducing amplifier, 14... Recording amplifier, 15...
・Demodulator, 16...Modulator, 17・External circuit, 18・
...Oscillator, 19...Power amplifier, 20...Diode, 21...
・Head selection switch. Representative patent attorney Akio Takahashi 11TJ Figure 2 (I12) (b)

Claims (1)

[Claims] 1) In a rotating head cylinder consisting of a rotating upper cylinder and a non-rotating lower cylinder, a light emitting and/or light receiving element is provided in a stationary position in or near the lower cylinder and in the upper cylinder, and a circuit in the upper cylinder is provided. A rotary head cylinder characterized in that part or all of the signal transmitted within the lower cylinder or between the external circuit at the stationary position is optically transmitted using the light emitting/receiving element.