Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Synchronizing moving-head moving-record recorders
Reexamination Certificate
1998-09-29
2001-10-09
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Synchronizing moving-head moving-record recorders
C360S073120, C360S073110, C360S073140, C318S560000, C386S349000
Reexamination Certificate
active
06301069
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a servo control apparatus, and, in particular, to a servo control apparatus which performs servo control of operation of a to-be-controlled object using software.
2. Description of the Related Art
There is a recording-medium reproducing apparatus in which a recording medium such as a magnetic tape is driven and information recorded in the recording medium is read.
Such an apparatus may have a pitch-control function for adjusting an information reading speed as a result of controlling a recording-medium feeding speed. Such an apparatus may perform the pitch control using hardware, specifically, using an analog circuit, or may perform the pitch control using software, specifically, using a microcomputer.
When the pitch control is performed in an analog manner by using discrete circuits, an IC, or an LSI circuit, a clock signal which is changed in accordance with a desired information reading speed is directly provided to such a circuit(s). On the other hand, when the pitch control is performed by using software, a clock of a fixed frequency is connected to a particular microcomputer, a special circuit detects data for the pitch control, and execution of the software is controlled so as to respond to the detected data, and, thus, the pitch control is achieved.
FIG. 1
shows a block diagram of one example of an information storing apparatus in the related art.
The information storage apparatus
100
stores digital sound information in a magnetic tape cassette for 8-mm VTR. The information storage apparatus
100
mainly includes a mechanical portion
101
, a servo microcomputer
102
, a system microcomputer
103
, a signal processing block
104
, a clock-signal generating portion
105
, an ATF circuit
106
, an A-D/D-A converting portion
107
, and a key operating portion
108
.
In the mechanical portion
101
, the tape cassette
110
containing a magnetic tape
109
is loaded, and the magnetic tape
109
is wound on a rotation drum
112
in which magnetic heads
111
are fixed.
The rotation drum
112
is rotated by a drum motor
113
. The magnetic tape
109
is sandwiched by a capstan motor
114
and a capstan roller
115
, and is caused to run at a predetermined speed as a result of the capstan motor
114
rotating. As a result, the magnetic tape
109
slides on the magnetic head
111
at a relative speed. Thus, a signal is read from tracks, which are formed on the magnetic tape
109
in a manner in which the tracks are inclined with respect to the tape running direction.
The thus-read signal is supplied to the signal processing block
104
. The signal processing block
104
demodulates the read signal and outputs the demodulated signal through the A-D/D-A converting portion
107
. Further, the signal processing block
104
generates a SERVO ref signal for controlling the rotation phase of the rotation drum
112
and provides the SERVO ref signal to the servo microcomputer
102
. The servo microcomputer
102
is connected with the drum motor
113
, the capstan motor
114
and so forth, and performs servo control of the rotation of the rotation drum
112
and the running speed of the magnetic tape
109
so that the relative speed between the magnetic head
111
and the magnetic tape
109
is fixed.
A fixed-frequency clock
116
is connected to the servo microcomputer
102
, and the servo microcomputer
102
operates using a clock signal provided by the fixed-frequency clock
116
. The servo microcomputer
102
performs the servo control through execution of a previously set software.
The system microcomputer
103
is connected to the servo microcomputer
102
, and the servo microcomputer
102
performs the servo control in accordance with commands and pitch data provided by the system microcomputer
103
. The key operating portion
108
is connected to the system microcomputer
103
, and the commands and pitch data are recognized by the system microcomputer
103
in response to key operation in the key operating portion
108
, operation of the system microcomputer
103
itself and operation of other external equipment. Then, the system microcomputer
103
provides the thus-recognized commands and pitch data to the servo microcomputer
102
and the clock-signal generating portion
105
. The system microcomputer
103
operates using a clock signal provided by a fixed-frequency clock
117
.
The clock-signal generating portion
105
has fixed-frequency clocks
118
and
119
, generates various clock signals, and provides the clock signals to the signal processing block
104
, ATF circuit
106
and A-D/D-A converting portion
107
. The ATF circuit
106
operates using the predetermined clock signal generated by the clock-signal generating portion
105
, detects an ATF error signal from a reproduced signal, and provides the detected ATF error signal to the servo microcomputer
102
.
The servo microcomputer
102
performs the servo control in accordance with the commands and ATF error signal. Also, at the time of pitch-control reproduction, the servo microcomputer
102
performs reproduction at a speed in accordance with the pitch data provided by the system microcomputer
103
.
FIG. 2
shows a flowchart of operation of the servo microcomputer
102
.
The servo microcomputer
102
is initialized by start of power supply or the like (in a step S
6
-
1
). Then, in response to the commands, which are provided by the system microcomputer
103
in response to an operation of a reproduction key in the key operating portion
108
, the servo microcomputer
102
starts control of the mechanical portion
101
through drum servo, capstan servo and so forth (in a step S
6
-
2
). Thus, the servo microcomputer
102
enters a reproduction condition.
In the reproduction condition, the servo microcomputer
102
performs a drum servo routine (a step S
6
-
3
), a capstan servo routine (a step S
6
-
4
), and a reel servo routine (a step S
6
-
5
) in sequence.
In the drum servo routine (the step S
6
-
3
), the capstan servo routine (the step S
6
-
4
), and the reel servo routine (the step S
6
-
5
), the pitch data which is provided by the system microcomputer
103
in accordance with the pitch data input through a key operation in the key operating portion
108
is processed through execution of software, and the servo control is performed.
In the drum servo routine (the step S
6
-
3
), the pitch data is recognized (in steps S
6
-
31
, S
6
-
32
). In the step S
6
-
31
, when the pitch data is 0%, that is, when the reproduction speed is not changed, a drum servo parameter for determining a reference condition for the drum servo control is set to a previously set reference value, and the drum servo control is performed (in steps S
6
-
33
, S
6
-
34
).
When the pitch data provided by the system microcomputer
103
has a positive value in the step S
6
-
32
, that is, when the reproduction speed is increased, the drum servo parameter is set to the value obtained as a result of the absolute value of the pitch data value being added to the previously set reference value, and the drum servo control is performed (in a step S
35
and the step S
34
).
When the pitch data provided by the system microcomputer
103
has a negative value in the step S
6
-
32
, that is, when the reproduction speed is decreased, the drum servo parameter is set to the value obtained as a result of the absolute value of the pitch data value being subtracted from the previously set reference value, and the drum servo control is performed (in a step S
36
and the step S
34
).
In the capstan servo routine (the step S
6
-
4
), the pitch data is recognized (in steps S
6
-
41
, S
6
-
42
).
In the step S
6
-
41
, when the pitch data is 0%, that is, when the reproduction speed is not changed, a capstan servo parameter for determining a reference condition for the capstan servo control is set to a previously set reference value, and the capstan servo control is performed (in a steps S
6
-
43
, S
6
-
44
).
When the pitch data provided by the system microcomputer
103
Faber Alan T.
Ladas & Parry
Teac Corporation
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