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— 78 —
Table 6-6. Reel Servo Mode
Mechanical Mode
During recording and playback
During FF and search
During REW and search
T Side Drive
Constant voltage drive
Constant linear speed servo
Constant voltage drive
S Side Drive
B.T. program servo
Constant voltage drive
Constant linear speed servo
Tape Speed (Increased Rate)
G0.5 (LP), G1 (SP)
G16 to approx. G200 (FWD direction)
G16 to approx. G200 (RVS direction)
G16 to approx. G200 (FWD direction)
G16 to approx. G200 (RVS direction)
Note) B.T. : Back tension
Table 6-6
shows the reel servo operations for each mode. During recording and playback, the data on the FWD torque
and FWD back tension adjustment stored in the EEPROM (IC517) is transmitted to the mechanism microprocessor
(servo process), and based on this data, the T side reel motor winds the tape by constant voltage driving, and at the S
side reel motor, optimum back tension is applied according to the tape position by the program servo so that the back
tension value is constant regardless of the tape position as shown in
(servo process), and based on this data, the T side reel motor winds the tape by constant voltage driving, and at the S
side reel motor, optimum back tension is applied according to the tape position by the program servo so that the back
tension value is constant regardless of the tape position as shown in
Fig. 6-11.
During FF/REW and search, when the drum is rotated at the same speed as playback (2000 rpm) while keeping the tape
running speed constant, the frequency of the playback signal fluctuates more sharply than normal playback, disabling the
reading of sub codes. To prevent this, the tape speed is controlled based on the data obtained in the measure mode so
that the liner speed becomes constant at the tape position of the reel motor at the take-up side. Furthermore, at this time,
the drum speed is also changed according to the tape running direction and tape position. The real motor at the supply
side adds the specified back tension to the tape by performing constant voltage drive.
running speed constant, the frequency of the playback signal fluctuates more sharply than normal playback, disabling the
reading of sub codes. To prevent this, the tape speed is controlled based on the data obtained in the measure mode so
that the liner speed becomes constant at the tape position of the reel motor at the take-up side. Furthermore, at this time,
the drum speed is also changed according to the tape running direction and tape position. The real motor at the supply
side adds the specified back tension to the tape by performing constant voltage drive.
Fig. 6-11. Back Tension by Program Servo During Recording and Playback
— 79 —
SECTION 7
MECHANICAL CONTROL CIRCUIT
Fig. 7-1. Schematic Diagram of Mechanical Control
This unit uses the main microprocessor (IC501) to control the whole system, the display microprocessor (IC701) to
control the display and manage inputs such as operation switches, and the mechanism microprocessor (IC502) to perform
mechanical section and servo control.
As shown in the schematic diagram of mechanical control in
control the display and manage inputs such as operation switches, and the mechanism microprocessor (IC502) to perform
mechanical section and servo control.
As shown in the schematic diagram of mechanical control in
Fig. 7-1
, the mechanism microprocessor (IC502) drives the
mechanism such as the motor and plunger.
The detection switches attached to the mechanism detect the mechanical mode such as OPEN/CLOSE of the cassette
compartment and completion of LOAD/UNLOAD of the tape path, as well as presence of cassette, and whether
recording is possible. The tape top is detected by the T end sensor (Q951) and the tape end is detected by the S end
sensor (Q950), which are made up of the LED and phototransistor equipped on both sides of the tape path system.
The mechanism section comprises of a loading motor (M901) which drives the tape path system and the cassette
compartment motor (M1) which drives the OPEN/CLOSE of the cassette compartment. They are controlled by the
mechanism microprocessor through the respective motor drive.
In addition to these, a brake plunger (PM901) for turning ON/OFF the T/S reel table brakes and FWD plunger (PM902)
for compressing/releasing the pinch roller are equipped.
The detection switches attached to the mechanism detect the mechanical mode such as OPEN/CLOSE of the cassette
compartment and completion of LOAD/UNLOAD of the tape path, as well as presence of cassette, and whether
recording is possible. The tape top is detected by the T end sensor (Q951) and the tape end is detected by the S end
sensor (Q950), which are made up of the LED and phototransistor equipped on both sides of the tape path system.
The mechanism section comprises of a loading motor (M901) which drives the tape path system and the cassette
compartment motor (M1) which drives the OPEN/CLOSE of the cassette compartment. They are controlled by the
mechanism microprocessor through the respective motor drive.
In addition to these, a brake plunger (PM901) for turning ON/OFF the T/S reel table brakes and FWD plunger (PM902)
for compressing/releasing the pinch roller are equipped.
MECHA MICON
(SERVO PROCESS)
IC502
25
+5V
CASSETTE
IN
RECENABLE
S901
S11
26
27
28
29
30
CASSETTE COMPARTMENT
LOCK
S12
CASSETTE COMPARTMENT
OUT
S902
UNLOAD
S903
LOAD
T-END
SENSOR
Q951
RV501
T-END
T-END
SENSOR
59 TEND
LED
DRIVE
Q518
46 TLED-ON
RV502
S-END
SENSOR
60 SEND
LED
DRIVE
Q519
47 SLED-ON
CAS-IN
REC-EN
CAS-LCK
CAS-OUT
UNLD-SW
LOAD-SW
16
15
18
17
3
6
LOADING
MOTOR
DRIVE
IC2
3
6
CASSE CON
MOTOR
DRIVE
IC523
7
2
M
M901
LOADING
MOTOR
7
2
M
M1
CASSETTE
COMPARTMENT
MOTOR
4
3
BREAK PM
DRIVE
Q506 - 508
510
PM901
BREAK
PLUNGER
INCLUDING
REEL MOTOR(M903)
FWD PM
DRIVE
Q504, 505
509, 511
PM902
FWD
PLUNGER
1
100
BPM-KI
BPM-ON
FPM-KI
FPM-ON
LM-LOAD
LM-EJECT
CM-IN
CM-OUT
S-END
SENSOR
Q950
5
D507
– 1
– 2
— 80 —
Fig. 7-2. Layout of Detection Switches
The switches perform the following detections to control the mechanism section and signal system, etc.
S901-1 CASSETTE IN:
Detects the presence of cassette
S901-2 REC ENABLE:
Detects the cassette’s rec-proof hole (recording is possible or not
possible)
possible)
S11 CASSETTE COMPARTMENT LOCK: Detects the lock (CLOSE) completion of the cassette compartment
S12 CASSETTE COMPARTMENT OUT:
S12 CASSETTE COMPARTMENT OUT:
Detects the completion of OUT (OPEN) of the cassette compartment
S902 UNLOAD:
Detects completion of unloading of loading mechanism
S903 LOAD:
Detects completion of loading of loading mechanism
Table 7-1
shows the detection state of the mode by the detection switches for each mechanism microprocessor input
terminal.
Table 7-1. Mode Detection by Detection Switch
IC502
(Mechanism Microprocessor)/
@∞ CAS-IN
@§ REC-EN
@¶ CAS-LCK
@• CAS-OUT
@ª UNLD-SW
#º LOAD-SW
@§ REC-EN
@¶ CAS-LCK
@• CAS-OUT
@ª UNLD-SW
#º LOAD-SW
“H” (SW ON)
Cassette present
Recordable
Cassette compartment CLOSE completed
Cassette compartment OPEN completed
UNLOAD completed
LOAD completed
“L” (SW OFF)
No cassette
Unrecordable
S903
S902
S901
S12
S11
7-1. Detection Switches of Mechanism Section
The mechanism section (DATM-55/56/57) has switches (S11, S12, S902, and S903) to detect the state of the mechanism
mode, and a switch (S901) which detects the presence of cassette and whether recording is possible. These switches are
connected to the mechanism microprocessor (IC502) as shown in the figure
mode, and a switch (S901) which detects the presence of cassette and whether recording is possible. These switches are
connected to the mechanism microprocessor (IC502) as shown in the figure
(Fig. 7-1.)
.
The detection switches are each attached to the mechanism section at the positions shown in
Fig. 7-2
.
— 81 —
7-2. Loading/Cassette Compartment Motor Drive Circuit
The mechanism section has a loading motor (M901) to drive the tape loading mechanism and a cassette compartment
motor (M1) to drive the OPEN/CLOSE of the cassette compartment. It is controlled by the mechanism microprocessor
(IC502) via the motor drive (IC2, IC523) which is composed of the similar circuit. As shown in the table of truth values
in
motor (M1) to drive the OPEN/CLOSE of the cassette compartment. It is controlled by the mechanism microprocessor
(IC502) via the motor drive (IC2, IC523) which is composed of the similar circuit. As shown in the table of truth values
in
Table 7-2
, when the operations of the motor drive M54641L set Pin 3 (IN1) to “H”, the motors rotate normally, and
the loading motor loads the cassette while the cassette compartment motor performs CLOSE cassette compartment
operation. When Pin 6 (IN2) is set to ‘’H”, the motors unload the cassette and perform OPEN cassette compartment
operation respectively. When both the input terminals 3 and 6 become ‘’H”, the brake mode is set. In this mode, the
motor will be stopped.
operation. When Pin 6 (IN2) is set to ‘’H”, the motors unload the cassette and perform OPEN cassette compartment
operation respectively. When both the input terminals 3 and 6 become ‘’H”, the brake mode is set. In this mode, the
motor will be stopped.
Fig. 7-3
shows the internal block diagram of the motor drive M54641L.
Table 7-2. Table of Truth Values for Motor Drive M54641L
Input
6
IN2
Output
7
OUT1
2
OUT2
OFF
L
H
L
OFF
H
L
L
3
IN1
Remarks
Loading motor
Cassette Compartment
Motor
Loading
Unloading
Cassette compartment CLOSE
Cassette compartment OPEN
IC stopped
Normal rotation
Reverse rotation
Brake
L
H
L
H
L
L
H
H
Motor Operation
1
CONSTANT
VOLTAGE
INPUT
CIRCUIT
CONTROL
CIRCUIT
3
6
8
5
7
2
4
IN1
IN2
GND
Vcc
Vcc
REF
OUT1
OUT2
OUTPUT
CIRCUIT
CIRCUIT
OUTPUT
CIRCUIT
CIRCUIT
INPUT
CIRCUIT
Fig. 7-3. Motor Drive M54641L Internal Block Diagram
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