Dynamic magnetic information storage or retrieval – Head mounting – For adjusting head position
Reexamination Certificate
1999-09-29
2001-10-09
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For adjusting head position
Reexamination Certificate
active
06301083
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to video tape recorders wherein a magnetic tape is wound around a rotary head cylinder to record signals on the tape or reproduce signals from the tape, and more particularly to video tape recorders (VTRs) wherein the distance of travel of the magnetic tape from the head cylinder to a control head is adjustable with high precision.
BACKGROUND OF THE INVENTION
With reference to
FIG. 14
, VTRs comprise a rotary head cylinder
2
mounted in a predetermined inclined posture on a chassis
1
, and a pair leading guide posts
4
,
41
arranged at opposite sides of the cylinder
2
and reciprocatingly movable along respective guide grooves
11
,
12
. A magnetic tape
10
is withdrawn from a tape cassette (not shown) and wound around the cylinder
2
by the advance of the guide posts
4
,
41
to provide a specified path of travel of the tape.
A supply reel support
3
and a take-up reel support
31
are arranged on the chassis
1
. Also arranged on the chassis
1
along the path of travel of the tape are a fixed guide post
42
, back tension post
43
, fixed guide post
44
, full-width erasing head
21
, sound erasing head
22
, sound/control head
23
, fixed guide post
45
, capstan
46
, pinch roller
47
and withdrawing guide post
48
. The capstan
46
, when driven, moves the tape
10
in one direction for recording or reproduction of signals.
As shown in
FIG. 11
, the sound erasing head
22
and the sound/control head
23
are mounted on a base plate
51
, collectively providing a magnetic head assembly
5
. The assembly
5
is supported by three post members
52
,
52
,
52
on a support table
9
.
Referring to
FIGS. 11 and 12
, the support table
9
is supported by a pivot
16
projecting from the chassis
1
and by bosses
14
,
15
provided on the chassis
1
. Two screws
91
,
92
extending through the support table
9
are screwed in the respective bosses
14
,
15
. The support table
9
are secured to the chassis
1
by tightening up these screws
91
,
92
.
The magnetic tape
10
for use in the VTR described is formed with a track pattern, on which the distance from the final end of B head recording track to the position where a control signal for the track is recorded (hereinafter referred to as the “X distance”) must be set at a predetermined value.
As shown in
FIG. 13
, the support table
9
has two holes
93
,
94
for inserting the two screws
91
,
92
therethrough. The holes
93
,
94
are each elongated along a circular arc centered about a hole
90
for inserting the pivot
16
therethrough. To adjust the X distance, the position of the sound/control head
23
is variable by moving the support table
9
about the pivot
16
as indicated by arrows in FIG.
11
.
In the step of assembling the VTR, the X distance is adjusted by loosening the two screws
91
,
92
to such an extent as to give some fastening force (prefastening force) to the support table
9
, then moving the support table
9
about the pivot
16
to a position where the predetermined X distance is realized, and tightening up the two screws
91
,
92
to fix the support table
9
in this position.
With the fastening mechanism wherein the screws
91
,
92
are used, the fastening force varies greatly with a slight difference in the state of the screws
91
,
92
as tightened. If the prefastening force of the two screws
91
,
92
is excessive, a great force is required to move the support table
9
, presenting difficulty in adjusting the X distance. If the prefastening force of the screws
91
,
92
is conversely too small, the support table
9
will shift during the adjustment of the X distance or when the screws
91
,
92
are tightened up after the distance adjustment, giving rise to the problem of producing an error in the X distance. There is another problem that the adjustment takes much time since each of the two screws
92
,
92
needs tightening in two steps.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a video tape recorder wherein the X distance is adjustable accurately with greater ease and within shorter period of time than in the prior art.
The present invention provides a video tape recorder wherein a position adjusting mechanism for supporting a control head on a chassis
1
comprises a support plate
6
having the control head mounted thereon, a pivotal support mechanism pivotally supporting a first end of the support plate
6
on the chassis
1
so as to move the control head toward or away from a rotary head cylinder, a clamp mechanism holding a second end of the support plate
6
on the chassis
1
by clamping to give resistance to the pivotal movement of the support plate
6
about the pivotal support mechanism, and a fastening mechanism engaging a third end of the support plate
6
with play for permitting the movement of the support plate
6
about the pivotal support mechanism and fixing the third end to the chassis
1
at an optional position within the range of the play to prevent the movement of the support plate
6
.
To adjust the X distance, a force for turning the support plate
6
about the pivotal support mechanism is applied to the support plate
6
, with the fastening mechanism loosened. The support plate
6
has its second end held by the clamp mechanism with a suitable definite clamping pressure and is pivotally movable within the range of play of the fastening mechanism, so that the support plate
6
is easily movable by the turning force, and the second end is shifted while being held clamped by the clamp mechanism. Accordingly, the support plate
6
is pivotally movable without necessitating a great force, and is further unlikely to move freely even with the fastening mechanism loosened.
After the adjustment of the X distance, the third end of the support plate
6
is fastened by the fastening mechanism to fix the support plate
1
to the chassis
1
. At this time, the support plate
6
has its second end held by the clamp mechanism with a suitable clamping pressure and is thereby given resistance to pivotal movement and accordingly unlikely to shift from the adjusted position. Since the mechanism to be manipulated in adjusting the X distance is limited only to the fastening mechanism, the adjustment can be made with greater ease within a shorter period of time than in the conventional case wherein two fastening mechanisms (screws) need to be manipulated.
Stated more specifically, the clamp mechanism comprises a resin clamp piece
7
secured to the chassis
1
, and the clamp piece
7
comprises a receiving portion
71
for receiving a rear surface of the second end of the support plate
6
and a holding portion
72
for holding a front surface of the second end of the support plate
6
under pressure, the second end of the support plate
6
being inserted between the receiving portion
71
and the holding portion
72
by a press fit. With this construction, the clamp piece
7
providing the clamp mechanism can be secured to the chassis
1
along with other members on the chassis
1
as by outsert molding. The present invention can therefore be practiced without entailing an increase in the number of fabrication steps.
According to another specific construction, the clamp mechanism is formed integrally with the chassis
1
and has a raised piece
82
holding with pressure a front surface of the second end of the support plate
6
received by a front surface of the chassis
1
, and the second end of the support plate
6
is inserted between the surface of the chassis
1
and the raised piece
82
by a press fit. Since the raised piece
82
can be formed integrally with the chassis
1
to provide the clamp mechanism, the present invention can be practiced with a smaller number of components than conventionally.
Further stated specifically, the fastening mechanism comprises a screw
91
extending through an elongated hole
62
formed in the support plate
6
and screwed in a boss
14
on the chassis
1
, and the support plate
6
is pivotally movable about the pivotal support mecha
Hogan & Hartson L.L.P.
Sanyo Electric Co,. Ltd.
Tupper Robert S.
Watko Julie Anne
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