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Manufacturing Test Process VLMF Monitor Sampling and Measurement System

IP.com Disclosure Number: IPCOM000122481D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 4 page(s) / 166K

Publishing Venue

IBM

Related People

Kennedy, H: AUTHOR [+2]

Abstract

This article relates to Very Low Magnetic Field (VLMF) testing of VDUs by automatic operation. It permits reduced manufacturing cost/cycle time through predictive sampling techniques of VLMF monitoring of magnetic field radiation emissions in a high volume environment.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 42% of the total text.

Manufacturing Test Process VLMF Monitor Sampling and Measurement
System

      This article relates to Very Low Magnetic Field (VLMF)
testing of VDUs by automatic operation.  It permits reduced
manufacturing cost/cycle time through predictive sampling techniques
of VLMF monitoring of magnetic field radiation emissions in a high
volume environment.

      Disclosed is a system which allows measurement of a small,
random sample while maintaining reliable product quality and saving
on the cost of 100% testing. The standalone system can be embedded in
any manufacturing process/site.  It is also adaptable for VLMF test
of PC printers with a change to a test fixture.  One system can test
many different product types on a single line (i.e., it is
concurrent).  It is predictive of sample size to ensure product
quality, and is statistically correct.  The software code is easily
changed to measure ELF for any future standard.

      Normally, an 82-point measurement of rate of change of a
magnetic field in MT/S and magnetic induction is taken at the design
stage to ascertain "worst" points/values as, for example, required by
the relevant Nordic Authorities on VLMF [1].  In manufacturing and
testing the product in high volume, the usual signal measurement is
at a "worst" point around the VDU.  However, in manufacturing VLMF
products, the test cycle time and cost of testing every VLMF product
is prohibitive.

      The system hardware total package shown in the figure is housed
in a custom built enclosure 1, and consists of a Magnetic Field Meter
3 [2], IBM 8530, Industrial Computer, Keyboard, Colour Display,
Digital Output Facility, mechanical test fixtures/locator 2 audible
indicators to indicate when a random sample would be taken and an
RS232 Comm link 6 between PC 5 and Magnetic Field Meter 3.  The
control software has a number of automatic and manually selectable
facilities as described below.

      For automatic operation, product information is added to the
system in the form of Product type, Name, Minimum and Maximum allowed
magnetic frequency and an Upper Warning Limit.  These form the
product record and are stored in the PRODUCT FILE (PRODUCT DAT).
Another value is requested for the product which is the INITIAL
NUMBER of machines to be sampled.  On entering this number, the
software activates a random number generation procedure which
calculates n numbers (where n = INITIAL NUMBER) between the values of
1 and m inclusive (and where m = number of minutes of production over
which the sample will be taken).  This gives the minutes during the
production cycle of the particular product that the system will call
for the "next" product built to be tested.  These random numbers are
stored in the RANDOM FILE which is created immediately after the
INITIAL NUMBER is entered.  The form name of this file is
product/model unique; i.e., IBM 8515 model 12 would give a RANDOM
FILE name of 851512.RAN.  A further file is create...