HP 5501A Operating And Service Manual page 97

3.7 COMPARATOR-BASED (CLOSED-LOOP) SYSTEMS. A special case of laser transducer
applications occurs in certain comparator-based (closed-loop) systems, such a s that shown in
Figure 3-4. The system controller sends the laser transducer system a digital representation
of the destination of the object under control. The transducer system then takes over the task
of measuring the object's position on a real-time basis, comparing it with the desired position,
controlling the drive motor, and indicating when the object under control has arrived at its
destination.
" ' y
o!;;p-
Mechanical Link
-----
1
Digital
Lnalog Drive
Voltage
t
Figure
3-4.
Comparator-Based (Closed-Loop) System Simplified Block Diagram
A typical comparator-based system (Figure 3-5) contains the following electronic equipment:
A system controller (calculator or mini-computer).
A 5501A Laser Transducer.
Two 10780A Receivers.
A 10740A Coupler.
Two 107624 Comparators.
A 107648 Fast Pulse Converter.
10746A Binary Interface.
A 10755A Compensation Interface.
A 10756A Manual Compensator.
Two power supplies (f15V and +5V).
Additional capability can be selected by adding the following electronic equipment:
a. Provide additional measurement axis (10762A Comparator and 107648 Fast Pulse Con-
verter. Note that each axis uses only one-half of the 107648 Fast Pulse Converter. There-
fore, two additional axes would require only one additional fast pulse converter).
b. Automatic compensation (replace 10756A Manual Compensator with the 5510A Opt 010
Automatic Compensator and 10563A Material Temperature Sensor).
This interface is used for applications where high-speed control functions are required. The
10764B Fast Pulse Converter (Figure 3-5) operates in conjunction with two 107624 comparators.
The 107648 provides up/down position counts to the two 10767A comparators and allows reso-
lution extension by factors of from 1 to 6 and 8 and 10 with high allowable slew rates. Refer to
Table 3-3 for typical specifications.
The 10755A Compensation Interface is used with either the 10756A Manual Compensator or the
5510A Opt 010 Automatic Compensator. In typical installations, the choice of manual or auto-
matic compensation i s determined by the stability of the ambient environment.