GB2173341A

GB2173341A - Signal transfer device for cylinder units

Info

Publication number: GB2173341A
Application number: GB08600341A
Authority: GB
Inventors: Tatsumaro Yamashita
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1985-04-02
Filing date: 1986-01-08
Publication date: 1986-10-08
Also published as: DE3603239C2; KR860008530A; DE3603239A1; GB8600341D0; JPS61229203A; KR900000626B1; GB2173341B

Abstract

A cylinder unit for use in a rotary head type tape recorder has a stationary cylinder (1) (Fig. 2) and a rotary cylinder (2), four magnetic heads 3A-3D on the rotary cylinder (2) two of which are recording heads 3A, 3B and two monitoring heads 3C, 3D, recording heads 3A, 3B being connected to the same, first, signal transfer path 30A, and monitoring heads 3C, 3D being connected to the same, second, signal transfer path 30B. When one of the two heads of either kind is in contact with tape (T), the other is not in contact with it. The reduced number of signal transfer paths assists miniaturization, enables turns of transformer coils to be increased in number and space between signal paths to be broaden to offset cross- talk. Slip-rings may replace the non- contact type transfer paths. <IMAGE>

Description

SPECIFICATION Signal transfer device for cylinder units The present invention relates to cylinder units for use in a rotary head type tape recorder for impressing audio or video signals onto, and recovering them from, magnetic tape. More particularly, the invention relates to a device for use in a small-sized cylinder to transmit signals from a plurality of magnetic heads with certainty.

A conventional cylinder unit of this kind is shown in Fig. 6. The magnetic heads incorporated in this cylinder unit are interconnected as shown in Fig. 5. The cylinder unit has a stationary cylinder 1 and a rotary cylinder 2.

Four magnetic heads 3A-3D are rigidly fixed to the rotary cylinder 2, which is firmly secured to a rotary shaft 4. The shaft 4 is rotatably held to the stationary cylinder 1 via bearings 5. A support plate 6 is mounted to the lower end of the shaft 4. A rotor magnet 7 mounted on the plate 6 is opposed to a stator coil 8 that is mounted at the lower end of the stationary cylinder 1. When the coil 8 is energized with electric current, the rotor magnet 7 is rotated; As a result, the rotary cylinder 2 rotates with the magnet 7.

A stator transformer 11 and a rotor transformer 12 are fixed to the stationary cylinder 1 and the rotary cylinder 2, respectively. The transformers 11 and 12 are each provided with four grooves, and the grooves in the transformer 11 are opposed to the grooves in the transformer 12. Coils are wound in these grooves. The coils on the rotary transformer 12 are connected to the magnetic heads 3A-3D mounted on the rotary cylinder 2. The coils on the stator transformer 11 are connected to a recording amplifier 13 and a playback amplifier 14, as shown in Fig. 5. That is, formed between the transformers 11 and 12 are four signal transfer paths 10A, 10B, 10C, 10D. The heads 3A and 3B are connected to the recording amplifier 13 through paths 10A and 10B, respectively. The heads 3C and 3D are tied to the playback amplifier 14 through the paths 10C and 10D, respectively.

In recent years, rotary head type tape recorders using cylinder units of this kind have become increasingly smaller. Accordingly, the diameter of such a cylinder unit has been required to be reduced. If the outside diameter of the stationary cylinder 1 and the rotary cylinder 2 is reduced to achieve a miniaturization, the stator transformer 11 and the rotor transformer 12 are reduced in size, as a matter of course. However, rotary head type tape recorders produced recently tend to have larger number of heads mounted thereon, to cope with special playback and other versatility in function. The result is that the intervals between the paths 10A-10D which are formed between the transformers 11 and 12 have been narrowed. Further, the number of turns of transformer coils in these coils 1 0A- 1 OD tends to decrease.Consequently, signals are transmitted over the paths with less certainty.

Also, there is the possibility that crosstalk occurs between the signals respectively fed to the recording amplifier 13 and the playback amplifier 14, because the paths 1 OA- 1 OD are too close to each other.

To cope with these problems, switch circuits 15 and 16 have heretofore been inserted in the input lines to the recording amplifier 13 and the playback amplifier 14, respectively, as shown in Fig. 5. When the magnetic heads 3A and 3C are in contact with tape, for example, the signal transfer paths from the heads 3B and 3D are cut off, or other similar operation is performed.

However, the provision of the switch circuits 15 and 16 as shown in Fig. 5 makes the circuit configuration more complex. Further, it is necessary that the grooves in the transformers 11 and 12 be machined accurately. This makes the machining operation more difficult.

Also, components have become more expensive to machine.

It is the object of the present invention to provide a signal transfer device which is used for a cylinder unit and which permits simplification and miniaturization of the structure of a signal transfer means including a stator transformer and a rotor transformer, prevents crosstalk between signals, and dispenses with switch circuits, etc.

The signal transfer device according to the invention is used for a cylinder unit comprising a stationary cylinder, a rotary cylinder, a plurality of magnetic heads mounted on the rotary cylinder, and contact type or non-contact type signal transfer paths formed between the two cylinders. The cylinder unit is characterized in that the signal transfer paths is fewer than the magnetic heads and that a plurality of magnetic heads are connected to each one signal transfer path.

According to the invention, a plurality of magnetic heads are connected to each one signal transfer path that is coupled to a common circuit. The heads are so disposed that when one of the heads is in contact with tape, the other is not in contact with the tape.

The signals from the heads are alternately transmitted through one signal transfer path.

Therefore, the signal transfer device has a less number of signal transfer paths and is simpler in structure than the prior art device.

A cylinder unit incorporating a singal transfer device embodying the invention will now be described, by way of example with reference to the accompanying diagrammatic drawings in which: Figure 1 is a circuit diagram showing the interconnection of the components of a signal transfer device for a cylinder unit according to the invention; Figure 2 is a side elevation half in cross section of the cylinder unit shown in Fig. 1; Figure 3 is a cross-sectional view of the rotary transformer shown in Fig. 2 and constituting a signal transfer path; Figure 4 is a schematic view for illustrating the manner in which tape is moved through a rotary head type tape recorder, as well as the arrangement of the heads;; Figure 5 is a circuit diagram showing the interconnection of the components of a conventional signal transfer device for a cylinder unit, and Figure 6 is a side elevation half in cross section of the conventional cylinder unit.

Referring to Fig. 4, a tape-recorder cassette 20 has a supply reel 21 and a take-up reel 22 therein. Tape T is trained around the reels 21 and 22. Guide rollers 23a-23h support the tape T and allow it to run when it is driven.

Of these rollers 23a-23h, the rollers 23b and 23c act to draw the tape T out of the cassette 20. The rollers 24a and 24b press the tape T against a cylinder unit according to the present invention.

As shown in Fig. 2, this cylinder unit consists of a stationary cylinder 1 and a rotary cylinder 2. Four magnetic heads 3A-3D are rigidly fixed to the rotary cylinder 2 in the same manner as the device shown in Fig. 6.

The rotary cylinder 2 is held to a rotary shaft 4, which is rotatably held to the stationary cylinder 1 via bearings 5. A support plate 6 is mounted at the lower end of the shaft 4 A rotor magnet 7 that is mounted on the plate 6 is opposed to a stator coil 8 disposed at the lower end of the stationary cylinder 1. As the coil 8 is energized with electric current, the magnet 7 is rotated, causing the cylinder 2 to turn.

As shown in Fig. 4, the four magnetic heads 3A-3D are spaced an angle 0 that is approximately equal to 900 from each other on the rotary cylinder 2. Of the four heads 3A-3D, the heads 3A and 3B are Sendust heads used for recording. The heads 3C and 3D are ferrite heads that are employed for monitoring subsequent to recording. Since the heads 3A-3D are spaced about 900 from each other as mentioned above, when one of the recording heads 3A and 3B is in contact with tape T, the other is not in contact with it. Similarly, the monitoring heads 3C and 3D alternately come into contact with the tape.

The stationary cylinder 1 and the rotary cylinder 2 are provided with a stator transformer 31 and a rotor transformer 32, respectively.

The transformer 31 has a set of grooves that is opposed to another set of grooves formed in the transformer 32. These grooves form two sets of signal transfer paths 30A and 30B.

As can be seen from the circuit diagram of Fig. 1, the recording heads 3A and 3B are connected to a common signal path and to a recording amplifier 13 via the signal transfer path 30A. The monitoring heads 3C and 3D are connected to a common signal path and to a playback amplifier 14 via the signal transfer path 30B. The signal transfer paths from the four heads are only two, i.e., 30A and 308, and so the width of the grooves can be made large even if the transformers 31 and 32 are made in small size. Thus, the number of turns of the coils within the grooves can be made large.

In the operation of the device constructed as described above, when the cassette 20 is installed, the rollers 23b and 23c pull out the tape T and wind it on the cylinder unit. During this operation, the tape T is transferred from the supply reel 21 to the take-up reel 22. At the same time, the stator coil 8 is energized, so that the rotary cylinder 2 is rotated together with the rotary shaft 4. Thus, the recording heads 3A and 3B perform recording operation, while the monitoring heads 3C and 3D perform playback operation.

The recording heads 3A and 3B are connected to the same signal transfer path 30A.

When the head 3A is in contact with the tape T, the other head 3B is not in contact with it.

Therefore, signals to be recorded which are delivered from the heads 3A and 3B alternately pass through the signal transfer path 30A and are applied to the recording amplifier 13. Similarly, signals from the monitoring heads 3C and 3D alternately pass through the signal transfer path 30B and are applied to the playback amplifier 14.

In the illustrated example, the signal transfer paths are non-contact type mechanisms using transformers. Contact type signal transfer paths using slip rings may be employed instead.

As can be understood from the description thus far made, the invention yields the following advantages.

(1) Even if a plurality of heads-am mounted on a rotary cylinder, signal transfer paths to a stationary cylinder can be made fewer than heads. This makes the structure of the signal transfer device simple.

(2) Especially, when a rotary transformer is used as a signal transfer path, grooves forming the signal transfer path are small in number. Hence, the diameter of the transformer itself can be made small. This can contribute to miniaturization of the whole player. Also, since the width of the grooves can be rendered broad, the number of turns of transformer coils can be made large. Consequently, the efficiency of transfer of signals can be enhanced.

(3) Because the signal transfer paths are small in number, the space between the signal transfer paths can be made broad. Hence, crosstalk between signals is less likely to occur.

Claims

1. A signal transfer device for use in a cylinder unit comprising a stationary cylinder, a rotary cylinder, and contact type or noncontact type signal transfer paths formed between the stationary and rotary cylinders, the rotary cylinder being equipped with a plurality of magnetic heads, the signal transfer paths being fewer than the magnetic heads, each one signal transfer path being connected with a plurality of magnetic heads.

2. A signal transfer device for use in a cylinder unit as set forth in claim 1, wherein when one of a plurality of magnetic heads connected to a common signal transfer path is in contact with tape, the other is not in contact with the tape.

3. A signal transfer device substantially as hereinbefore described, with reference to Figs.

1 to 4 of the accompanying drawings.