You will have noted in IEC 60950-1 Clause 4.2.5 Impact Test, that it states "the test is not applied to flat panel displays or to the platen glass of equipment (for example, copying machines)".
The waiver for flat panel displays appeared in the third edition of IEC 60950 - some time ago I trawled back through all my IEC committee papers trying to find the justification for this change - but couldn't find anything. I spoke to some committee members who seemed to think it was included because LCDs couldn't withstand the impact test ! The real issue, however, is whether there is a hazard in the LCD display that requires a degree of protection. I am aware of 2 possible hazards : High voltage present at the lamps within the LCD. In all the LCDs we use in our Automated Teller Machines (ATMs), I perform the limited current test and prove that the circuitry used meets the requirements for a limited current circuit. I would also conduct a short circuit test on the driver circuit for the lamp(s) - usually an oscillator feeding thru a transformer - but typically the power output is so low that the oscillator shuts down when a short is applied to the output transformer. The second possible hazard might be considered to be the chemicals present in the LCD. This has been the subject of some debate, the conclusion (based on information from LCD suppliers) being that there is no chemical hazard present. If you want any further details, let me know and I can probably recover something from my files. Regards, John Crabb, (Product Safety) , NCR Financial Solutions Group Ltd., Discovery Centre, 3 Fulton Road, Dundee, Scotland, DD2 4SW E-Mail :john.cr...@scotland.ncr.com Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. From: Speakman, Jim [mailto:jim.speak...@uk.thalesgroup.com] Sent: 09 September 2003 08:19 To: 'emc-pstc' Subject: LCD Displays and Safety IT equipment Standards (BS EN 60950) define mechanical safety requirements for display screens of the Cathode Ray Tube type in order to provide protection from implosion. LCD displays do not manifest this hazard, but does anyone know of any International or National Standards requirements anywhere that mandates the minimum structural integrity, and/or provision of protective devices for LCD displays from accidental damage that may lead to a hazard resulting in an accident to personnel? __________________________ Jim Speakman (Design Safety Representative (Southern Sites) Thales Defence Ltd Thales Sensors Manor Royal Crawley West Sussex RH10 9PZ > * Tel: +44(0)1293 644911 > * Mob: +44(0)7968 529439 > * Fax : +44(0)1293 644194 > * e-mail jim.speak...@uk.thalesgroup.com This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
