SHIMPO 933 - Manual (Page 15)

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continues until the elastomer tip on the cylinder reaches the switch. The tip and the
switch now begin to deform until the electrical contact first closes. When the measured
contact resistance falls below the SLTV for the first time, a free running counter is read to
record this initial event. Each time, including the first time that the measured contact
value transitions through SUTV and then SLTV, the counter is latched. At the end of the
testing, the initial latched count is subtracted from the recurring latched count to calculate
the time interval. If there is only a single transition, both latched counts are identical and
the difference is zero, a no bounce condition.
At some point in time, the contact should stabilize. The LCTS continues to monitor the
contact resistance until the end of the half test cycle. This end point will be a timed event
that will be discussed shortly. When the cycle end occurs, the LCTS will make a final
measurement of the contact. This is the measured value used for the contact resistance
testing. This value is temporarily stored by overwriting the previous down contact
resistance. If the test data is transferred to the PC, this last down contact value will be
available for inspection, otherwise it is lost when the next cycle occurs.
The down contact value is compared against the Minimum Down Contact Resistance
and the Maximum Down Contact Resistance . If the value is less than the minimum
tolerance, a Min Contact Failure occurs. If the value is greater than the maximum
tolerance, a Max Contact Failure occurs. The down contact value is also compared
against a Maximum Contact value. If the down contact value is greater than the current
Maximum Contact value, the Maximum Contact value is replaced with the down contact
value. This is the new maximum. Similarly, the Minimum Contact value is replaced with
down contact value if this new reading is less than the Minimum Contact value. This
becomes the new minimum. These values can be reset so that the worst readings are
returned. The
Maximum Contact value is reset to 0, and the Minimum Contact value is
initialized to “open”. These values are never tested, but are returned to the PC running
the application software so that they can be inspected.
The down bounce value is compared against the Maximum Down Bounce time. If the
new value exceeds the Maximum Down Bounce time, down Bounce Failure occurs.
Similar to the contact resistance, the bounce measurement has a Maximum Bounce
value. When the new bounce value is greater then the Maximum Bounce value, the
Maximum Bounce value is replaced with the new value. This value is never tested, but
is reported back to the application software. The reset value of the Maximum Bounce
value is 0. The last down bounce value is also available for download from the tester
and is display by the application software.
The LCTS checks the failures at the end of the up half cycle. If any failures have
occurred in either the down or up stroke of this cycle, the cycle has failed. The internal
failure counter is then incremented. For each failed cycle, the
Failure Counter this
counter has one added to it. The count limit is 65,535,000. The Sequential Failure
counter is also incremented. It also has a maximum limit of 65,535,000 counts.
However, when the test cycle passes all test conditions, the
Sequential Failure counter
is reset to 0. For all test cycles, whether they pass or not, the Cycle Count is
incremented. This keeps track of the total cycle applied to the device under test. All