Specifications

CARROLL TOUCH Chapter 1 - Introduction to Infrared Touch Systems
Touch System Programmer’s Guide 1-5
failure, the touch system simply suffers a localized loss of resolution in
one coordinate axis, rather than being completely inoperable.
Criteria for Failing a Beam
The touch system considers a beam to be interrupted if the IR light level
at the phototransistor is below a threshold level. A beam is considered
failed if it appears to be interrupted for a given period of time.
The touch system detects failed beams:
• During power up.
• When the touch system is reset using the SFP Reset (45H)
command or BREAK.
• When the touch system diagnostics are run using the SFP
Run_Diagnostics (3AH) command.
• While the touch system is scanning the beams during normal
operation.
In the first three cases, the time required to fail a beam is less than one
second. In the last case, the time required to fail a beam is determined
by the failed beam timing parameters.
The touch system maintains a table of beams that have been determined
to have failed.
Failed Beam Timing Parameters
The values for the various failed beam timing parameters are different
for ASIC-based touch systems and non-ASIC-based touch systems, as
shown in Table 1-1.
A touch system is probably ASIC-based if it is a modular touch system,
or an invasively integrated Smart-Frame with a five switch
Communication Parameters jumper block on the frame. If you are
Table 1-1. Failed Beam Timing Parameters
Parameter
ASIC-
Based
Non-ASIC-
Based
Valid Touch Fail Time 59 - 62 sec. 225 - 270 sec.
Non-Contiguous Touch Fail Time 2.2 - 4.4 sec. 10 - 20 sec.
Single Axis Touch Fail Time 2.2 - 4.4 sec. 10 - 20 sec.
Unfail Time 2.2 - 4.4 sec. 10 - 20 sec.