Cursor control system for VDU - receives AM signals from remote hand-held unit to set position on screen

摘要

The operator uses a hand-held control unit to alter the position of a cursor arrow on the screen of a VDU. When the push-button control on the hand-held unit is pressed, four infra-red LEDs in the unit transmit bursts of short pulses of radiation. The phase differences between the bursts is such that they occur in a repetitive equally-spaced sequence. The infra-red sensor on the front of the VDU receives the signal. Because of the orientation of the LEDs, some of the bursts will have greater amplitude than others. The operator tilts the controller, the resultant changes in amplitude are detected by a circuit in the VDU and used to change the cursor position.