Safety of test systems in DC production testing of OLED displays

Many electrical test systems and test instruments are capable of measuring or sourcing hazardous voltages and power levels. Furthermore, if something goes wrong (e.g., a programming error or an instrument malfunction), hazardous levels can be sourced even though the system indicates that no hazard exists. The presence of these high voltages and powers means that operators must be protected from the hazards. Protection methods include the following:
• Test fixtures should be designed to prevent operators from contacting any hazardous circuits.
• The device under test must be completely enclosed to protect the operator from any flying debris.
• Double insulation is used for all electrical connections that the operator may contact. Double insulation ensures that the operator is protected even if one layer of insulation fails.
• Use high-reliability, fail-safe interlock switches to disconnect power when the test fixture cover is opened.
• Use automated robotic arms to replace manual operations when conditions permit; this way, the operator does not need to reach into the test fixture and disconnect protective circuits.
• Provide proper training to all system users so that they are aware of all potential hazards and know how to protect themselves from harm.

It is necessary to ensure that the personal safety protection provided to operators and maintenance personnel is in place and effective; this is the responsibility of the test system designer, integrator, and installer.

Equipment List
• Model 7002 Switch System Mainframe, supporting 10 Scanner Cards and GPIB communication control.
• Four Model 2400 SourceMeter instruments.
• Model 2361 Trigger Controller
• Five Model 8503 DIN to BNC Trigger Cables • Six GPIB Cables • Model 7015-C Solid State Relay 1 × 40 Multiplexing Switch ( 1 card for every 80 display columns and 1 card for every 40 display rows ) • Model 7011-MTC-2 Mass Terminated Cable Assemblies (one for each 7015-C card) • Model 7011-MTR 96- pin DIN Male Connector (one for each 7011-MTC-2 ) Example Program Keithley has developed a demonstration program to operate this system configuration. This program is available on the Keithley website at: http://www.keithley.com . Please note that this program is provided to illustrate the concepts presented in this article. The program may need to be modified to fit the desired test parameters and timing.