"Performance" here is used to describe "how well" the Touch Sensor Module (TSM) is in performing the task of reporting touches.
Listed below are some ways to measure performance for the Touch Sensor Module (TSM).
For further information regarding the definitions, refer to TSM - Definitions.
Accuracy (Measurement)
The purpose of the TSM is to report the position of a physical object. The accuracy (in short) is the difference between the reported and the physical position of the object (finger) in front of the TSM. The touch accuracy of the TSM can be described statistically with the normal distribution and a standard deviation of 2 sigma. This means that the touch position reported by the sensor module will deviate less than the specified value in 95% of the cases, when the whole object (finger) is inside the Touch Active Area.
The goal is to measure and calculate the deviation (accuracy) for a TSM of a specific size and configuration when test object is moved inside the Touch Active Area. This is done using a robot to increase the repeatability.
Linearity (Measurement)
When moving an object in a straight line in front of the TSM, the fluctuations (deviation) from that line can be measured.
The goal is to measure and calculate the deviation (accuracy) for a TSM of a specific size and configuration when a test object is moved in a line infront of the TSM. This is done using a robot to increase the repeatability.
Power Consumption (Measurement)
The TSM will consume different amount of power depending on load and configuration.
The goal is to measure the power consumption for a specific TSM size, configuration and (HW/SW) protocol for idle (33 Hz) and active (100 Hz) mode.
Latency / Response Time (Measurement)
The time between when an object (finger) enters the light beam (and is detected as a touch) of the TSM and when the touch position is reported to the host, can be measured as latency / response time. The reaction time of the TSM can be limited by several factors such as TSM size, Idle frequency, protocol and host configuration. If the TSM has filters such as floating protection activated, this will also affect the latency.
The goal is to measure the latency for each specific TSM size, default configuration and (HW/SW) protocol for default scanning range (normal) at an idle frequency of 33 Hz.
Scanning and Reported Frequency (Measurement)
The frequency of the reported touches from the TSM to the host is limited by several factors such as number of touches, TSM Size, scanning frequency, scanning range, protocol, host configuration, etc.
The goal is to measure the maximum reported frequency for a specific TSM size and default scanning range.
Endurance Tests
Standby
This test is to verify that the TSM can be in idle mode (standby) over an extended period of time.
The goal is to have no false positive touches and no unknown errors over 72 hours.
Load over time
This test is to verify that the TSM works without crashes or unknown error over time. The TSM is operating in idle and active mode over an extended period of time.
The goal is to have no unknown error and a responsive TSM over 72 hours.
Detection of false positive touches
This is a part of the Standby and Load (over time) test. During the test, it is possible to determine if a touch is "valid" (expected) or false and unwanted.
The goal is to have no "unexpected" touches (false positive touch) during the tests. A common description of "false positive touches" is "ghost touches".
For more specifications and information about the performance test methods, contact Neonode Support.