JPS6260727B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drum device for a video tape recorder, and its purpose is to completely scan a recording signal during special playback, namely still playback, slow motion playback, and quick motion playback. The objective is to improve the playback output and obtain a complete playback image without noise.

An embodiment of the present invention will be described below in comparison with a conventional example.

Figures 1 to 3 show conventional examples; Figure 1 shows a tape running system for a recording/playback method called helical scan in a video tape recorder (hereinafter referred to as VTR); A view of the rotating upper drum 1 viewed from the mounting surface side of the magnetic heads 8, 8 is shown. The outer peripheral surface of the rotating upper drum 1 has a diameter of 180 mm.
A pair of windows 2, 2 are bored with a phase difference of °,
The magnetic heads 8, 8 are configured to protrude from the pair of windows 2, 2, respectively. 3 is the lower drum, which is arranged coaxially with the upper drum 1, and is
Fixed to the main body. Reference numeral 4 denotes a tape as a magnetic recording medium, which is wound obliquely around a cylinder consisting of an upper drum 1 and a lower drum 3 through posts 5 and 6, and is guided along a stepped guide 7 formed on the lower drum 3 by an arrow. Strike in direction A. Note that the upper drum 1 is driven by a drum motor (not shown) and rotates in the direction of arrow B. Reference numeral 9 denotes screws for fixing the pair of magnetic heads 8, 8 facing the windows 2, 2 of the upper drum 1. FIG. 3 shows the reproducing state when the tape 4 is viewed from the magnetic surface side, and the magnetic heads 8, 8 are arranged at the third scanning angle during each reproducing operation, which will be described later.
It moves from the bottom of the diagram to the top. The shaded area 10 represents the magnetization recording pattern and forms an angle θ _N with respect to the tape end. Reference numeral 11 represents the head trajectory axis when the tape 4 stops running, that is, the head trajectory during still playback. Since the tape 4 is scanned by the magnetic heads 8, 8 while the tape 4 is stopped running, the angle θ _N is Scanned at different angles θo. 12 is the slow motion playback trajectory,
Since the tape running speed is slower than in normal playback, an angle θs is formed between the scanning angle θo during still playback and the scanning angle _θN during normal playback. Reference numeral 13 indicates a quick motion playback locus, which forms an angle θ _Q larger than the scanning angle θ _N because the tape running speed is higher than during normal playback.

In this way, for recording pattern 10, still,
When performing each slow motion and quick motion reproduction, head reproduction is performed with the slopes of θ _N -θo, θ _N -θs, and θ _Q -θ _N for the recorded pattern 10, respectively. In cases other than reproduction, the magnetic heads 8, 8 do not completely follow the recording pattern 10, resulting in insufficient reproduction output and problems with reproduced images in terms of SN ratio, noise, etc. One possible way to avoid this problem is to correct the tape running angle by lifting the tape guide according to the error angle that occurs during each playback, but the amount of correction and the tape guide itself also require precision. Therefore, it is insufficient as a countermeasure.

In contrast, the present invention can avoid the above problems as follows.

Figure 4 is a plan view corresponding to Figure 2, Figure 5 is an exploded perspective view, Figures 6 and 7 are U-V of Figure 4.
A cross-sectional view is shown, where 14 is an upper drum in which a pair of windows 16, 16 are bored with a phase difference of 90 degrees from the windows 2, 2, and 17, 17 are a pair of identical semicircular bimorphs. It is made of piezoelectric ceramic and is fixed at both ends thereof by a pair of fastening members 18, 18 with screws 20, 20, 20, 20 so as to form a substantially annular shape on the ring member 19.

The tightening members 18, 18 have bimorph piezoelectric ceramics 17 fixed at the fixing part and the fulcrum.
Projecting surfaces 21 and 22 are provided, and a projecting surface 23 is provided on the bimorph piezoelectric ceramic fixing portion of the ring member 19. Also, the ring member 19
has a notched groove 24 and is configured to be easily elastically deformed, and is coaxially fixed to the central recessed portion of the upper drum 14 with a screw 25. Reference numerals 15 and 15 denote a pair of magnetic heads, which are fixed to the middle part of the bimorph piezoelectric ceramic 17 corresponding to the position of the window 16, and the magnetic head 15 is connected to the magnetic head 8.
The depth of the center recess of the upper drum 14 and the height of the ring member 19 are taken into consideration so that the height is low compared to It is formed. A set screw 26 functions to adjust the relative height of the magnetic heads 15, 15 and to match the height of the magnetic head 8, and is arranged at the bottom of the central recess of the upper drum 15 and at a position where it can come into contact with the ring 19. has been done.

FIG. 6 shows the state of the magnetic heads 15, 15 before adjustment, and FIG. 7 shows the state after adjustment. In this way, a part of the ring member 19 is pressed by the set screw 26, and the ring member 19 is elastically deformed using the notch groove 24 as a fulcrum, and the magnetic heads 15, 15 on the bimorph piezoelectric ceramics 17, 17 are The height can be adjusted individually. For convenience of explanation, FIG. 7 is shown in an exaggerated manner compared to the actual state. Further, as described above, the cutout groove 24 is provided to facilitate deformation of the ring 19 and to protect the end of the bimorph piezoelectric ceramic 17 from coming into contact with the ring member 19, but it may not be provided separately.

With the structure described above, recording is performed using the pair of magnetic heads 8, 8, and then the pair of magnetic heads 15, 15 is used for reproduction, thereby recording information on the bimorph piezoelectric ceramics 17, 17. Applying voltage, bimorph piezoelectric ceramic 1
7 and 17, a predetermined displacement is caused substantially in the thickness direction of the pair of magnetic heads 15 and 15.
If the magnetic heads 15 are set to give a displacement according to the head scanning angle error during each special playback, the magnetic heads 15, 15 will move over the recording pattern 10 during each playback of still, slow motion, and quick motion. can be completely scanned. This makes it possible to improve the reproduced image by increasing the signal-to-noise ratio and eliminating noise. Moreover, the bimorph piezoelectric ceramic can obtain any displacement by adjusting the applied voltage, and the low speed ratio and double speed ratio during special reproduction can be freely adjusted to a certain extent. Furthermore, the bimorph piezoelectric ceramic 17 is integrated with the ring member 19 so that it can be attached to and detached from the upper drum 14, and the set screw 2
Since the height of the pair of magnetic heads 15, 15 can be adjusted individually using 6, 26, the height of the magnetic head 180
゜Maintenance such as indexing, assembly, and replacement is easy. Since the bimorph piezoelectric ceramic 17 has a structure in which most of it is protected by the ring member 19 and the like, great effects such as a reduced risk of breakage can be obtained.

8 to 10 show other embodiments, FIG. 8 is a plan view corresponding to FIG. 4, FIG. 9 is an exploded perspective view, and FIG. 10 is an X-Y sectional view of FIG. 8. be. 8 to 10, regarding the assembly of the ring 19, the bimorph piezoelectric ceramic 17, and the tightening member 18, the tightening member 18 in the previous embodiment is
The vertical relationship between the ring member 19 and the ring member 19 is reversed. Further, the upper drum 27 is provided with two fixing surfaces for the ring member 19 on the same plane as the fixing surfaces for the pair of magnetic heads 8, 8, and as shown in FIG.
The ring member 1 is arranged so that the main surfaces of the bimorph piezoelectric ceramics 17, 17 on the side where the magnetic heads 15, 15 are fixed are at the same height as the ring fixing surfaces 28, 28.
A bimorph piezoelectric ceramic is fixed to the lower part of 9. In this way, dimensional accuracy such as the depth of the recess of the upper drum 27, the thickness of the ring member 19, and the thickness of the bimorph piezoelectric ceramic 17 is not required, and the processing can be greatly simplified. Furthermore, even if the heights of the magnetic heads 15, 15 differ from each other due to warpage of the bimorph piezoelectric ceramic 17, they can be easily adjusted to the same height by using the setscrews 26, 26. Therefore, the same effects as in the previous embodiment can be expected.

In each of the above embodiments, the upper drums 14 and 27
, two sets of magnetic heads 8, 8, 15, and 15 were provided, respectively, and the bimorph piezoelectric ceramic 1
It is also possible to perform recording and reproduction using only the magnetic heads 15, 15 disposed on the magnetic heads 7, 17.

As explained above, according to the present invention, it is possible to completely scan the recorded signal during each reproduction of still, slow motion, and quick motion, improve the reproduction output, and obtain a complete reproduced image without noise. Can be done.

[Brief explanation of the drawing]

Figures 1 to 3 show a conventional example. Figure 1 is a perspective view of a helical scan tape running system, Figure 2 is a configuration diagram of the main parts of Figure 1, and Figure 3 is an explanatory diagram of the recording/playback state. , FIGS. 4 to 7 show an embodiment of the present invention, FIG. 4 is a configuration diagram of the upper drum, FIG. 5 is an exploded perspective view of FIG. 4, and FIGS. 6 and 7 are diagrams of FIG. 4. U-
V sectional view, FIGS. 8 to 10 show other embodiments, FIG. 8 is an upper drum configuration diagram, FIG. 9 is an exploded perspective view of FIG. 8, and FIG. 10 is an X-- It is a Y cross-sectional view. 14, 27... Upper drum, 15, 15... Magnetic head, 17, 17... Bimorph piezoelectric ceramic, 18, 18... Tightening member, 19... Ring member, 26... Set screw.

Claims (1)

[Claims] 1. A magnetic tape is wound obliquely around the outer periphery of a drum containing a rotating magnetic head to form a magnetic recording pattern having a predetermined inclination angle with respect to the longitudinal direction of the magnetic tape, thereby recording and recording signals. In a drum device that performs playback, a pair of bimorph piezoelectric ceramics each having a magnetic head fixed therein is mounted inside a rotatably supported drum, the bimorph piezoelectric ceramics are supported between a clamping member, and the drum is rotatably supported. a ring member disposed coaxially on the drum; and a set screw mounted on a portion of the drum facing the ring member, the set screw being capable of vertically adjusting each of the magnetic heads by pressing a portion of the ring member. A drum device characterized by: 2 The pair of bimorph-shaped piezoelectric ceramics each have a substantially semicircular shape, and both ends thereof are opposed to each other so as to have a substantially ring shape, and both ends are connected to a pair of tightening members. 2. The drum device according to claim 1, wherein the bimorph piezoelectric ceramics are fixed to a ring member so that each of the bimorph piezoelectric ceramics is displaced in the thickness direction thereof in accordance with an applied voltage. 3. A pair of magnetic heads are fixed to a head mounting surface portion formed on a rotatable drum that guides the running of the magnetic tape, and a ring member is attached to the mounting surface portion formed flush with the head mounting surface portion of the drum. is fixed coaxially with the rotational axis of the drum, and the ends of a pair of bimorph piezoelectric ceramics each having a roughly semicircular shape with a magnetic head attached to the center of one main surface are The magnetic head is clamped and fixed to the ring member by a pair of clamping members so that the main mounting surface of the magnetic head is at the same height as the mounting surface of the ring member, and the magnetic head is fixed to the ring member at a position facing each clamping member of the drum. By pressing a part of the ring member through the tightening member,
A drum device characterized in that screws are provided for vertically adjusting the magnetic heads attached to the bimorph piezoelectric ceramic.