Pan And Tilt Motor Control Circuit - Panasonic BB-HCM580A Service Manual

BB-HCM580A
4.5.

Pan and Tilt Motor Control Circuit

PAN drive motor and TILT drive motor are driven under the control from the CPU (IC102).
[PAN drive control]
PAN drive control circuit is mounted on the CPU board.
For the PAN drive control, the CPU (IC102) generates a variety of pulses that are applied to the PAN motor diver (IC120) to con-
trol the speed and direction of the rotation of the motor. In addition, current to the PAN motor is controlled by applying the refer-
ence voltage to the motor driver (IC120). The reference voltage is generated based on the DA output from the DA converter
(IC119) that is connected to the data bus of the CPU (IC102) and the current to the PAN motor is used to control the torque of
the PAN motor and to micro-step drive (2W1-2) the motor. The micro step drive is the method to increase the rotational resolu-
tion of the motor, and with this method of the micro step drive the accuracy of 0.9375° (7.5°/8) has been achieved for the PAN
motor minimum step angle of 7.5°. The motor control signal from the motor driver (IC120) for the PAN drive is applied to the PAN
drive motor via the 4-pin connector (CN104).
In the position control, the home position for the PAN control is detected by the PAN sensor (IC116; photo coupler) when the
power is turned on, and then the position is open-loop controlled by the software. In order to remove variations among products,
the output from the PAN sensor (IC116) is input into the comparator (IC107) and the output (PAN_S) from the comparator is
detected in the CPU (IC102).
The motor drive power supply (VM voltage) for the PAN drive motor driver (IC120) is +12V that is supplied from the IO board.
[TILT drive control]
The TILT drive control circuit is mounted on the TILT board.
The TILT motor driver (IC954) and TILT sensor (IC952) are mounted on the CPU board.
For the TILT drive control, the CPU (IC102) on the CPU board generates a variety of pulses that are applied to the TILT motor
driver (IC954) to control the speed and direction of the rotation of the motor. Since the TILT drive control does not require such
rotational resolution as required in the PAN drive control, but the "W1-2" control method is used. In the TILT drive unit, the accu-
racy of 1.875° (7.5°/4) has been achieved for the TILT motor minimum step angle of 7.5°. The motor control signal from the
motor driver (IC954) for the TILT drive is applied to the TILT drive motor via the 4-pin connector (CN953).
In the position control, the home position for the TILT control is detected by the TILT sensor (IC952; photo coupler) when the
power is turned on, and then the position is open-loop controlled by the software. In order to remove variations among products,
the output from the TILT sensor (IC952) is input into the comparator (IC107) on the CPU board and the output (TILT_S) from the
comparator is detected in the CPU (IC102).
The motor drive power supply (VM voltage) for the TILT drive motor driver (IC954) is +12V that is supplied from the IO board via
the CPU board.
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