Carrol Touch TouchSystems CarrollTouch Prog, Руководство программиста

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Chapter 1 - Introduction to Infrared Touch Systems CARROLL TOUCH
1-2 Touch System Programmer’s Guide
Overview
A Carroll Touch infrared touch system consists of a touch controller and
touch frame or a combined touch frame and controller. The touch
system uses scanning infrared (IR) beam technology to detect operator
input. Generating an invisible grid of IR light beams in front of the host
video display screen, the touch system reports touch input when the IR
light field is interrupted by a stylus (typically a finger). This input can
be used by a touch application just as similar applications use input from
pointing devices such as a mouse, light pen or trackball.
Touch Frames
The typical Carroll Touch touch frame is a thin, flat rectangle comprised
of four joined printed circuit boards (PCBs). Two adjacent PCBs contain
arrays of IR light emitting diodes (LEDs), while the other two PCBs
contain arrays of phototransistor/receivers. Each IR LED and the
phototransistor opposite it is called an opto-pair. The IR LED of each
opto-pair emits an IR light beam that is detected by the phototransistor.
The x-axis and y-axis arrays of opto-pairs are pulsed sequentially to
create a grid of IR beams, as shown in Figure 1-1.
Figure 1-1. Infrared Touch Frame
A beam, or a beam pair, consists of an IR LED and phototransistor
directly across from each other in the touch frame.
Touch Controller
The touch controller is the circuitry required to create and monitor the
IR grid. A sequence of electrical pulses is sent to the LEDs to create the