JPS60201502A - rotating head cylinder - Google Patents

Abstract

PURPOSE:To decrease the number of channels of a rotary transformer required for connecting to an external circuit and also to improve the deterioration of the S/N of a reproducing signal by allowing a rotary head side of a VTR to switch selectively required heads (normally two heads) and using a common channel so as to connect only the selected rotary head to the external circuit. CONSTITUTION:When selective changeover switches 9a-9d art thrown to upper side contacts, a couple of narrow track use rotary heads 3a, 3b are selected and when the selective changeover switches 9a-9d are thrown to lower contacts conversely, a couple of wide track rotary heads 3c, 3d are selected, and the selected rotary heads are connected to the external circuit through two channels 51, 52 of the rotary transformer 5 via a recording amplifier or a reproducing amplifier in response to the changeover position of recording/reproducing changeover switches 7a-7f. The number of required channels of the rotary transformer 5 is four in total; two for transmitting a recording/reproducing signal and one each for power transmission and for transmitting a switching control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rotary head cylinder used in a helical scan type video tape recorder (hereinafter abbreviated as VTR).

[Background of the invention]

In a helical scan type VTR, a rotary head cylinder having the structure shown in FIG. 1 is generally used. As is well known, the rotary head cylinder comprises, for example, an upper cylinder 1 to which two rotary heads 3a and 3b are attached, a lower cylinder 6, and a rotary transformer 5 provided within these cylinders 1.6. The upper cylinder 1 is connected to the rotating shaft 4 of the motor 2 and rotates integrally with the rotating heads 6a and 3b, and the lower cylinder 6 is fixedly installed opposite to the upper cylinder. The rotary transformer 5 is composed of a rotor 5a and a stator 5b, which are coaxially attached to the upper cylinder 1 and the lower cylinder 6, respectively, and are configured to closely face each other.

As is well known, the rotary transformer 5 transmits and receives recording and reproduction signals when the rotary heads 3a and 3b helically scan a magnetic tape (not shown) to perform recording and reproduction. In this method, a rotary transformer having as many transmitting and receiving channels as there are rotary heads was used, and each rotary head was connected to a recording and reproducing amplifier provided outside the rotary head cylinder through its own transmitting and receiving channel. FIG. 2 shows an example of such a conventional manner of coupling the rotary head and the recording/reproducing amplifier. Figure 2 shows a head 3a for a narrow track and rack.

3b and wide track heads 5c and 3d are each coupled to recording/reproducing amplifiers 8a to 8d using four-channel rotary transformers 5. In addition,
7a to 7d in FIG. 2 are recording/reproduction changeover switches.

By the way, in general, the structure of the rotary transformer 5 is
As shown in the plan view and cross-sectional view in Figures (a) and (b), the required number of channels (in the example shown in the figure, 3
a number of concentric grooves 5'a, 5' equal to the channel)
b, 5'c are provided, coils (not shown) are inserted into these grooves, and two such circular cores (rotor 5a and stator 5b) are made to face each other with their grooved surfaces facing each other. Since such a rotary transformer 5 is disposed inside the rotating head cylinder as described above, the outer diameter of its core 5' is limited by the outer diameter of the rotating head cylinder, and the number of grooves, that is, the number of channels is limited. has its limits.

However, as VTRs have become more sophisticated in recent years, the number of rotating heads attached to the upper cylinder has increased to include heads for narrow tracks, heads for wide tracks, heads for PCM audio, heads for special playback, and heads for field still playback. A total of seven to eight heads, etc., are now required. On the other hand, V
As the outer diameter of the rotary head cylinder tends to become smaller as TRs become smaller, it is almost impossible to manufacture a rotary transformer with as many as 8 channels.

Therefore, the above-mentioned conventional techniques have the disadvantage that the number of rotary heads, that is, the function of the VTR itself, is limited by the rotary transformer.

Further, in the above conventional technology, a rotary transformer 5 is provided between the rotary heads 3a to 6d and the recording/reproducing amplifiers 8a to 8d.
intervenes, so the noise component mixed in from the rotary transformer 5 during playback is amplified together with the playback signal,
This was a cause of deterioration of the S/N ratio of the reproduced signal.

, [Object of the Invention] It is an object of the present invention to eliminate the drawbacks of the above-mentioned prior art, eliminate the limitation on the number of usable rotary heads by the number of channels of the rotary transformer, and improve the S/N ratio of the reproduced signal. The purpose of the present invention is to provide a rotating head cylinder that can be rotated.

[Summary of the invention]

To achieve this objective, the present invention provides a method for connecting multiple rotary heads to an external circuit at the rotary head side, instead of coupling a large number of rotary heads to an external circuit using a unique channel for each rotary head as in the prior art. The number of rotary transformer channels required for coupling is reduced by selecting and replacing the required heads (usually two) and coupling only the selected rotary heads to the external circuit using a shared channel. , the amplification of the recording/reproduction signal by each rotary head is also performed on the rotary head side to improve the above-mentioned deterioration of the S/N of the reproduced signal. Therefore, in the present invention, a selection switching circuit for the rotary head is provided. , a recording/reproducing amplifier and an accompanying recording/reproducing switching circuit are provided in an upper cylinder that rotates integrally with the rotary head, and operating power is supplied from the outside to the amplifier and switching circuit that are necessary at this time. A dedicated channel is provided in the loader transformer to carry out alternating current.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows a first embodiment of a rotary head cylinder according to the present invention. In the diagram shown, the same reference numerals as in FIG. 2 are given to the parts corresponding to the conventional example of FIG. 2. In this embodiment, recording and reproducing amplifiers 8a to 8d,
The recording/reproduction changeover switches 78 to 7f, the rotary head selection changeover switches 9a to 9d, etc. are provided in the upper cylinder (not shown) to which the rotary heads 6a to 3d are attached. -9d is switched to the upper contact, a pair of rotating heads 3a for narrow tracks.

3b is selected, and conversely, when the selection changeover switches 98 to 9d are switched to the lower contact, 1 for wide track is selected.
A pair of rotary heads 5c and 5d are selected, and these selected rotary heads are connected to the rotary transformer 502 channels 51° via a recording amplifier or a reproducing amplifier depending on the switching position of the recording/reproducing changeover switches 78 to 7f. 52
is connected to external circuitry. Each of the above changeover switches 7a
~7f, 9a~9d, etc. are preferably electronic switches using diodes or the like, and these are switched in conjunction with each set of changeover switches by the changeover control circuit 14 based on an external changeover control signal. . The means for supplying the switching control signal from the outside will be described later. Recording/reproducing amplifiers 88-8d, changeover switches 7a-7f9a-9d,
If the switching control circuit 14 and the like are integrated into an IC, they can be placed near the rotary head and the wiring becomes simple.

By the way, in order to operate the recording and reproducing amplifiers, each changeover switch, changeover control circuit, etc., some operating power is required, and in the embodiment shown in FIG. It is supplied from the outside through a dedicated channel 53.

That is, an oscillator 1o provided outside the rotary head cylinder is oscillated at a high frequency (for example, 20 MHz) that does not interfere with recording/reproducing video signals, and after amplifying the oscillation output with a power amplifier 11, the oscillator 1o is connected to a dedicated channel of the rotary transformer 5. 53 to the rotating head side (upper cylinder) and rectified by the diode 12, the required DC operating power can be obtained.

In the embodiment shown in FIG. 4, the switching control signals for the respective changeover switches described above are multiplexed with the high frequency wave for power transmission and transmitted, and the switching control circuit 14 discriminates these signals and selects the changeover switches 7a to 7f.

Switching control is performed for each of 9a to 9d.

Since the switching control signal may be a digital signal, various methods such as FM modulation and two-frequency superimposition can be used as a multiplexing method. However, the above-mentioned method of varying the DC operating power is not preferred.

The transmission of the switching control signal does not necessarily need to be multiplexed to the high frequency for power transmission, and
It is also possible to provide a dedicated channel for this purpose. In this case, the required number of channels of the rotary transformer 5 is 2 for transmitting the recording/reproducing signal, 1 each for power transmission and switching control signal transmission, and a total of 4 channels. In addition to the narrow track heads 3a, 31) and wide track heads 3c, 5d, if a special playback head, field still playback head, etc. are added as rotating heads, recording and playback of video signals can be performed without any problem. It is capable of transmission. However, in this case, the configuration of each changeover switch, the number of recording and reproducing amplifiers, etc. in FIG. Needless to say, things need to be changed.

FIG. 5 is a block diagram showing a second embodiment of the present invention.
The difference from the embodiment shown in FIG. 4 is that there are only two sets of recording/reproducing amplifiers (8a, 8b), and these are shared by the narrow track heads 3a, 5b and the wide track bases 3c, 3d. This is what we did. For this purpose, narrow track heads 5a, 3b and wide track heads 5c, 5d are used.
are selectively switched by selection switches 9a and 9b and connected to recording and reproducing amplifiers 8a and 8b. The embodiment of FIG. 5 is otherwise similar to the fourth embodiment.
Although there is essentially no difference from the embodiment shown in FIG. 8, as is clear from the figure, the configurations of the selection changeover switches 9a, 9b and the recording/playback changeover switches 7a to 7d are simpler as the number of recording/playback amplifiers is smaller. It has become a thing.

FIG. 6 is a block diagram showing a third embodiment of the present invention,
In this embodiment, the rotary head selection switch 1
3 not only performs selective switching between the narrow track heads 3a, 3b and the wide track heads 5c, 3d, but also performs head switching (usually, this Such head switching is also performed on the VTR main body side. In this way, each rotating head 6a~
6d requires only one transmission system for recording and reproducing signals, and in the embodiment shown in FIG. It becomes possible to perform all signal transmissions. Therefore, in this embodiment, the required number of channels for the rotary transformer 5 is two channels, the channel 51 for transmitting the recording/reproducing signal and the channel 53 for power transmission, regardless of the number of rotary heads. . (Selection switch 13 and recording/playback switch 7
a.

It is assumed that the switching control signal for 7b is multiplexed with a high frequency wave for power transmission. ) Other configuration 1 effects of the embodiment in FIG. 6 are as shown in FIGS. 4 and 5.
Since it is similar to the embodiment shown in the figure, repeated explanation will be omitted.

It should be noted that the configuration of the selection changeover switch 13 is merely shown schematically, and it goes without saying that in reality it can be implemented by appropriately combining electronic switches.

〔Effect of the invention〕

As explained above, according to the present invention, the number of rotary heads that can be used is not restricted by the number of channels of the rotary transformer, so even when converting to VTReTR, it is possible to use a large number of rotary heads, and it is possible to use a wide variety of rotary heads. It is possible to realize a VTR having excellent functions, and it is also possible to improve the S/N deterioration of the reproduced signal due to the rotary transformer, and to provide a rotary head cylinder with excellent functions by eliminating the drawbacks of the prior art.

[Brief explanation of drawings]

Figure 1 is a diagram showing the structure of a general rotating head cylinder.
Fig. 2 is a block diagram showing a conventional manner of coupling a rotary head and a recording/reproducing amplifier, and Figs. 5(a) and (b)
1 is a plan view and a sectional view showing the structure of a general rotary transformer, and FIGS. 4 to 6 are a first embodiment and a second embodiment of the present invention, respectively. It is a block diagram showing a 5th example. 1... Upper cylinder 3a-3d... Rotating head 5.
...Rotary transformer 6...Lower cylinder 7a~7
f... Recording/reproduction changeover switch 8a-8d... Recording and playback amplifier 9a-9d, 13... Rotating head selection changeover switch 10... Oscillator 11... Power amplifier 12... Rectifier diode 14...Switching control circuit agent Patent attorney Akira Takahashi 1 Figure ``Sagi'' 2 Atsushi Norikata 3 Q- (b)! 4 Review t5 Figure

Claims (1)

[Claims] A plurality of rotary heads are provided, an upper cylinder that rotates integrally with these rotary heads, a lower cylinder that is fixedly installed opposite to the upper cylinder, and these cylinders are installed in the upper and lower cylinders and are used for recording and reproducing signals. In a rotary head cylinder having a rotary transformer for transmitting and receiving data, a recording/reproducing amplifier and a switching circuit for selecting and switching the rotary head and recording/reproducing are built into the upper cylinder, and the number of recording/reproducing amplifiers is less than the number of rotary heads. The recording/reproducing signal is transmitted and received through a rotary transformer having a number of channels, and the operating power of the recording/reproducing amplifier and the switching circuit is supplied in the form of alternating current through the rotary transformer.
Rotating head cylinder with t% characteristics.