GB2150733A

GB2150733A - Magnetic recording and reproducing device of the rotatable cylinder type

Info

Publication number: GB2150733A
Application number: GB08428672A
Authority: GB
Inventors: Toshide Irisa; Tatsumaro Yamashita
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1983-11-28
Filing date: 1984-11-13
Publication date: 1985-07-03
Also published as: DE3443368A1; GB8428672D0; KR850009672U; JPS6089643U; KR890005506Y1; GB2150733B

Abstract

A rotary-head magnetic recording and reproducing device has a chassis (1) provided with a pair of guiding grooves (6, 6'), a rotating cylinder (3) supporting magnetic recording and reproducing heads. a pair of movable members (5, 5') movable along the guide grooves, each of the members (5, 5') supporting a vertical tape-guide post (7, 7') and an oblique post (8, 8'), and a pair of arms (9a, 13a) swingable about pivot pins (10, 14) for supporting an erasing head (9) and an impedance roller (13), respectively. The improved device includes a base plate (19) separately secured to the chassis (1) and supporting both the rotating cylinder (3) and the pivot pins (10, 14) around which the aforementioned arms (9a, 13a) are pivotal. <IMAGE>

Description

SPECIFICATION Magnetic recording and reproducing device of the rotatable cylinder type This invention relates to a rotary cylinder type magnetic recording and reproducing device to be used for a video tape recorder.

Fig. 1 illustrates a tape feed mechanism provided in a conventional rotary cylinder type magnetic recording and reproducing device to be used for a video tape recorder (hereinafter termed VTR) which comprises a chassis 1, a base plate 2 secured to the chassis 1 for supporting a rotatable cylinder 3, pole catchers 4 and 4' secured to the chassis 1 by means of screws, and members 5 and 5' which are movable along two grooves 6 and 6' formed in the chassis 1 in such a manner that the distance between the grooves 6 and 6' increases outwardly. The movable members 5 and 5' support vertically extending posts 7 and 7' and obliquely extending posts 8 and 8'. A whole-width erasing head 9 is mounted on an arm 9a rotatable around a pivot pin 10 that is secured to the chassis 1.

A guide roller 11 and a tension post 12 are also secured to the chassis 1. An impedance roller 13 is rotatably mounted on an arm 1 3a which is in turn rotatably supported by a pivot pin 14 secured to the chassis 1. A voice erasing head 15 and a voice controlling head 16 are secured to a head mounting plate 17 secured to the chassis 1. Numeral 18 designates a magnetic tape extending into the recording and reproducing device.

According to the upward movement of the movable members 5 and 5' under the guide of the guiding grooves 6 and 6', the vertical posts 7 and 7' secured thereto are moved upward as viewed in Fig. 1 together with the obliquely disposed posts 8 and 8' until the vertical posts 7 and 7' abut against the pole catchers 4 and 4', respectively, so that the magnetic tape 18 is pulled out of a cassette (not shown) to be loaded around the rotating cylinder 3. One part of the magnetic tape 18 thus loaded is brought into contact with the guide roller 11 and the whole-width erasing head 9 by the tension post 12, while the other part of the magnetic tape 18 is brought into contact head 16 by means of the impedance roller 13.

With the above described construction of the conventional device, however, the pivot pins 10 and 14 secured to the chassis 1, while the rotatable cylinder 3 is supported by the base plate 2 constituting a separate member from the chassis 1. Thus the positional references for the two pivot pins 10 and 14 and the rotating head cylinder 3 are different from each other, so that although the two pivot pins 10 and 14 are provided vertically to the chassis 1, there is a possibility of a positional deviation between the rotating cylinder 3 and the two pivot pins 10 and 14.

With such deviation, the magnetic tape 18 extended along the cylinder 3 tends to be twisted between the oblique post 8 and the whole-width erasing head 9 and also between the other oblique post 8' and the impedance roller 13. The twist of the tape 18 entails either one or all of the following disadvantages: (1) Movement of the magnetic tape 18 becomes unstable, (2) Wow flutter tends to occur, (3) The magnetic tape 18 tends to be damaged, thus adversely affecting the stable extraction of the control signal (or voice signal).

An object of the present invention is to provide a rotating cylinder type magnetic recording and reproducing device wherein the above described drawbacks of the conventional device can be substantially eliminated.

Another object of the invention is to provide a rotating cylinder type magnetic recording and reproducing device wherein the occurrence of twist in the magnetic tape between the oblique post and the erasing head and also between the other oblique post and the impedance roller can be substantially prevented.

The above described and other objects of the invention can be achieved by a rotating cylinder type magnetic recording and reproducing device according to the present invention which is characterised in that a base plate is provided separately from a chassis for supporting a rotating cylinder supporting recording and reproducing heads, and pivot pins for rotatably supporting an erasing head and impedance roller are provided integrally with said base plate.

A tape feeding mechanism embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a plan view of a tape feeding mechanism of a conventional rotating cylinder type magnetic recording and reproducing device applied to VTR; Figure 2 is a plan view of a tape feeding mechanism of a rotating cylinder type magnetic recording and reproducing device according to the present invention which is also applied to VTR; Figure 3 is a left side view of an important part in Fig. 2; Figure 4 is a right side view of another important part in Fig. 2; Figure 5 is a plan view of a base plate provided in the device of Fig. 2 for supporting a rotating cylinder; Figure 6 is a sectional view of the base plate along the line A-A in Fig. 5; and Figure 7 is a sectional view of the base plate along the line B-B in Fig. 5.

The mechanism will now be described in detail with reference to Figs. 2-7 wherein similar members as those in Fig. 1 are designated by similar reference numerals.

In Fig. 2 there is indicated a base plate 19 which is made of a die-cast product having an excellent machinability at a high precision. As shown in Figs. 6 and 7, the base plate 19 is provided with holes 20 and 21 for securing pivot pins 10 and 14 around which a wholewidth erasing head 9 and an impedance roller 13 are supported rotatably, and further holes 22 and 23 for securing pole catchers 4 and 4'. In the holes 20 and 21, the pivot pins 10 and 14 are inserted vertically through the base plate 19 and secured to the base plate 19 in a force fit, thread engagement, or welding manner. Likewise, the pole catchers 4 and 4' are secured to the base plate 19 by driving screws 24 into the holes 22 and 23 shown in Fig. 5.The construction of the embodiment, other than the above described base plate 19 and the associated members, is quite similar to the construction of the conventional recording and reproducing device shown in Fig. 1.

Since the pivot pins 10 and 14 and the rotating cylinder 3 are secured to the commonly provided base plate 19 as described above, these three members are positioned with reference to a single member of the base plate 19. Furthermore, the holes 22 and 23 for mounting the pole catchers 4 and 4' as well as the holes 20 and 21 for securing the pivot pins 10 and 14 can be machined simultaneously during the machining of the base plate 19, and therefore the machining work of these holes can be substantially simplified.In addition, since the pivot pins 10 and 14 and the rotating cylinder 3 are positioned in a correct mutual relation as described above, the hereinbefore described difficulties of twisting magnetic tape 18 between the obliquely disposed post 8 and the erasing head 9 and also between the oblique post 8' and the impedance roller 13 can be substantially eliminated, and the following advantageous features can be obtained.

(1) The magnetic tape 18 can be moved in a stable manner.

(2) Creation of wow flutter can be prevented.

(3) Occurrence of tape damage can be prevented.

More specifically, the twisting of the magnetic tape 18 running between the rotating cylinder 3 and the voice control head 16, which adversely affects stable extraction of the control signal (voice signal), can be prevented effectively.

Since the pivot pins rotatably supporting arms provided for supporting the erasing head and impedance roller, respectively, are secured into the holes formed in the commonly provided base plate, positioning of the rotating cylinder and the pivot pins is facilitated.

Furthermore, since these holes can be formed simultaneously at the time of the production of the base plate, the production operation of these parts can be simplified. The holes 22 and 23 for securing the pole catchers are also formed in the base plate for enhancing the above described advantageous features. As a consequence, twisting of the magnetic tape between one of the oblique posts and the erasing head and also between the other of the oblique posts and the impedance roller can be prevented, and the operational characteristics of the magnetic tape can be substantially improved.

Claims

1. A rotating cylinder type magnetic recording and reproducing device comprising a chassis provided with a pair of guiding grooves, a rotating cylinder supporting magnetic recording and reproducing heads, a pair of movable members movable along said guiding grooves provided in said chassis and each supporting a vertical post and an obliquely disposed post for guiding a magnetic tape around one part of said rotating cylinder, and a pair of arms swingable around pivot pins for supporting an erasing magnetic head and an impedance roller, respectively; the improvement wherein a base plate is separately provided to be secured to said chassis, and said rotating cylinder and said pivot pins around which said arms are swingable are supported in said base plate.

2. A rotating cylinder type magnetic recording and reproducing device as set forth in claim 1 wherein holes for securing said rotating cylinder and said pivot pins are provided through said base plate, and said pivot pins are inserted into said holes to be secured therein while said rotating cylinder is secured by means of screws driven through said holes.

3. A rotating cylinder type magnetic recording and reproducing device as set forth in claim 1 wherein a pair of pole catchers are also provided for catching said vertical posts supported by said pair of movable members, respectively, and said pair of pole catchers are also secured to said base plate supporting said rotating cylinder and said pivot pins.

4. A device as set forth in claim 2 wherein said pivot pins are inserted into said holes and secured therein by either a force fit, threaded engagement or welding.

5. A magentic recording and reproducing device substantially as hereinbefore described with reference to Figs. 2 to 7 of the accompanying drawings.