Carrol Touch TouchSystems CarrollTouch Prog, Руководство программиста

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Chapter 1 - Introduction to Infrared Touch Systems CARROLL TOUCH
1-6 Touch System Programmer’s Guide
unsure whether your system is ASIC-based and if you need to know the
values of the failed beam timing parameters, use the touch system
diagnostics software (CTDIAG) to observe the amount of time required
to fail beams that are interrupted by a valid touch.
Table 1-1 gives a range of values rather than a specific value because the
touch system firmware checks for failed beams at a regular interval (2.2
seconds or 10 seconds). A beam that appears to be interrupted just after
the firmware checks takes longer to fail than a beam that appears to be
interrupted just before the firmware checks.
Note
Custom touch systems may have different values for the failed
beam timing parameters from those given in Table 1-1.
During normal operation, with the touch system scanning the beams, a
beam is considered failed if it is interrupted for the amount of time
specified by the Valid Touch Fail Time parameter and if the pattern of
interrupted beams appears to indicate a valid touch with a single stylus.
(A touch is considered valid if there appears to be one and only one
region of contiguous interrupted beams in each coordinate axis.) Thus,
a single stylus that remains stationary within the touch screen for the
Valid Touch Fail Time causes beams to be failed.
If beams are interrupted on only one axis of the touch frame, the
interrupted beams are failed in the amount of time specified by the
Single Axis Touch Fail Time parameter.
For any other pattern of interrupted beams, such as more than one region
of interrupted beams in an axis, the interrupted beams are failed in the
amount of time specified by the Non-Contiguous Touch Fail Time
parameter. Thus, multiple styli that remain stationary for longer than the
Non-Contiguous Touch Fail Time result in beams being failed, as do
non-contiguous touches.
For example, if you place a piece of tape over the opto-devices in one
axis of the touch screen, the beams obstructed by the tape are determined
by the touch system firmware to be failed and are added to the failed
beam table only after the amount of time specified by the Invalid Touch
Fail Time parameter has elapsed. If you then remove the tape, the time
specified in the Unfail Time parameter must elapse before the beams are
considered unfailed by the touch system firmware.