Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1999-07-16
2003-01-21
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S027000, C360S031000
Reexamination Certificate
active
06510018
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic recording and reproducing apparatus such as a videotape recorder utilizing a helical scanning method and a method for checking adjustment statuses of a rotary head thereof.
FIG. 10
to
FIG. 12
are provided to illustrate a conventional method for checking adjustment statuses of the rotary heads of a magnetic recording and reproducing apparatus.
FIG. 10
is a block diagram showing the configuration of the magnetic recording and reproducing apparatus and an adjustment device connected thereto.
FIG. 11
illustrates a method for checking whether a preset value (hereinafter referred to as an X value) of a tracking value, which is a time interval corresponding to a distance X
0
between a magnetic tape trace position by a control head and a magnetic tape trace position by the rotary head, is within a predetermined range.
FIG. 12
illustrates a method for checking whether the rotary head appropriately traces the recording track on a standard magnetic tape throughout its length (hereinafter referred to as a linearity check).
In a conventional X value check, an operator who adjusts the X value first mounts a standard magnetic tape for checking the X value (a cassette tape, for instance)
71
on the magnetic recording and reproducing apparatus to be checked (video deck to be tested)
50
. On the standard magnetic tape
71
for checking the X value, the channel-
1
video track
73
, which is wider than the rotary head (video head)
12
a
of the target magnetic recording and reproducing apparatus
50
, is recorded, and the channel-
2
video track
74
indicated in
FIG. 10
is not recorded. The width of the channel-
1
video track
73
extends to the right in FIG.
10
and is greater than the width of the rotary head
12
a
. The operator next brings the magnetic recording and reproducing apparatus
50
into the play mode by using a remote controller
43
or the like, adjusts a manual tracking variable resistor (VR)
61
to decrease a high tracking value to a low value in stages, and manually sets such a tracking value that a video reproduction envelope output S
16
obtained by amplifying an output S
12
of the rotary head
12
a
reaches a transition point P
1
from a flat portion A
1
to an oblique portion A
2
, as shown in FIG.
11
. Then, the operator turns on the X value preset command switch (SW)
62
to return the tracking value to the preset value (which is, the X value), compares a value V
p1
of the video reproduction envelope output corresponding to the tracking value at the point P
1
and a value of the video reproduction envelope output corresponding to the X value, and judges, if a difference between the two values is within a predetermined range, that the X value set by the magnetic recording and reproducing apparatus
50
meets the format standard.
Further, a conventional linearity check (which is a compatibility check with respect to the trace status of the rotary heads of the magnetic recording and reproducing apparatus) is made by checking the flatness of the video reproduction envelope output S
16
(the amplitude corresponds to a width of an overlapping area of a trace range of the rotary head
12
a
or
12
b
and the video track) when the tracking value is varied. The operator who checks the linearity first mounts a standard magnetic tape for the linearity check (a cassette tape, for instance)
72
on the magnetic recording and reproducing apparatus
50
to be checked. On the standard magnetic tape
72
for the linearity check, the channel-
1
video track
73
and the channel-
2
video track
74
, which are narrower than the rotary heads
12
a
and
12
b
of the target magnetic recording and reproducing apparatus
50
, are recorded. The operator next brings the magnetic recording and reproducing apparatus
50
into the play mode by using the remote controller
43
or the like, and adjusts the manual tracking variable resistor
61
to change the tracking value so that video reproduction envelope output S
16
is maximized in both sections in which a drum FF signal S
21
, which is a control signal to electrically switch the output of the rotary heads
12
a
and
12
b
, is high and low (the value is set to five divisions, for instance, as shown in FIG.
12
). The operator next changes the tracking value to reduce the maximum value of the video reproduction envelope output S
16
(to four divisions, for instance, as shown in FIG.
12
). If the minimum value of the video reproduction envelope output S
16
in a single cycle of the drum FF signal S
21
is greater than or equal to a predetermined value (Z divisions, for instance, as shown in FIG.
12
), the flatness of the video reproduction envelope output is judged to meet the requirement and the target magnetic recording and reproducing apparatus
50
is judged to meet the linearity specified on the format.
In the above-mentioned conventional methods for checking adjustment statuses, however, the operator manually adjusts the tracking value, and the operator carries out checks on the X value and linearity of the magnetic recording and reproducing apparatus
50
by measuring a change in the video reproduction envelope output S
16
, which indicates the relative positional relationship between the rotary head
12
a
or
12
b
and the track pattern. Therefore, the operator must have some experience, the time required to make a check depends on the operator, and the check accuracy may also depend on the operator. Since the standard magnetic tapes used for the X value check and linearity check are not the same, the operator gets a heavy workload of changing the tracking value of the different standard tapes separately.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for checking adjustment statuses of a magnetic recording and reproducing apparatus which takes some load off the operator and by which differences in experience and capability of operators do not affect the results of the check and the check period, and to provide a magnetic recording and reproducing apparatus which has a structure for executing the method for checking adjustment statuses or for allowing the method for checking adjustment statuses to be executed.
According to one aspect of the present invention, a method for checking adjustment statuses of a magnetic recording and reproducing apparatus is executed after a standard magnetic tape having a reference track recorded using the helical scanning method is loaded into the magnetic recording and reproducing apparatus and the system control means receives a command to start a play mode for checking adjustment statuses; and
the method for checking adjustment statuses of the magnetic recording and reproducing apparatus comprises the steps of:
(a) setting a play mode for tracing a track of the standard magnetic tape by the rotary head, according to a command sent from the system control means to the servo means, and then varying the tracking value in stages within a predetermined range;
(b) generating an envelope detected output having a magnitude corresponding to an output from the rotary head for each of a plurality of tracking values within the predetermined range;
(c) sampling values of the envelope detected output in predetermined positions within a single tracing by the rotary head, for each of the plurality of tracking values within the predetermined range;
(d) obtaining a tracking value corresponding to a maximum of the values sampled from the envelope detected output; and
(e) outputting a result of a check on whether the preset value is within a predetermined permissible range, according to a difference between the obtained tracking value and the preset value.
Further, values of the envelope detected output are sampled in a plurality of positions within a single tracing in the step (c);and the method for checking adjustment statuses further comprising the step of:
(f) outputting a result of a check on whether adjustment has been made so that a width of an overlapping area of a trace range by the
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