1、I v) a w I- f - EIA TEPL05-15 88 3234600 O007356 8 M - - TEPAC PU B L ICAT ION CRT Screen and Glass Ageing Procedures TEP10545 OCTOBER 1988 ELECTRONIC INDUSTRIES ASSOCIATION ENGINEERING DEPARTMENT EIA TEPL05-15 88 3234600 0007357 T .A NOTICE EIA Engineering Standards and Publications are designed to
2、 serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such
3、Standards and Pub- lications shall not in any respect preclude any member or non-member of EIA from manufacturing or selling products not conforming to such Standards and Publications, nor shall the existence of such Standards and Publications preclude their voluntary use by those other than EJA mem
4、bers, whether the standard is to be used either domestically or internationally. Recommended Standards and Publications are adopted by EIA without regard to whether or not their adoption may involve patents on articles, materials? or processes. By such action, EIA does not assume any liability to an
5、y patent owner, nor does it assume any obligation whatever to parties adopting the Recom- mended Standard or Publication. This Standard does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Stan
6、dard to establish appropriate safety and health practices and to determine the applicability of regu- latory limitations before its use. Copyright 1988 Published by s ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 2001 Eye Street, N.W. Washington, D.C. 20006 PRICE: $10.00 Published in U.S.
7、A. - EIA TEPL05-15 88 3234600 0007358 I TEP105-15 CRT SCREEN AND GLASS AGEING PROCEDURES This publication was formulated under the cognizance of the JT-31 Committee on Optical Characteristics of Display Devices and approved by the Tube Engineering Panel Advisory Council (TEPAC). The TEP105 series of
8、 publications comprises a set of test methods developed for industrial cathode ray tubes. They are intended to be useful in evaluating cathode ray tubes with respect to parameters, which are of interest to users of these devices. i EIA TEP105-15 8 m 3234600 0007359 3 m L TEP105-15 CRT Screen and Gla
9、ss Aqeinq Procedures Introduction to the Glass and Screen Aqeinq Procedures This procedure is broken down into three subsections. They are: I. Glass Ageing Thi5 procedure tests the ageing properties of CRT glass alone, independent of screening conditions or phosphors. II. Pre-Ageing This procedure t
10、ests the often rapi.d initial ageing of the complete CRT system. This test may be used alone or as a pre-test before long term ageing. III. Long Term Ageing This procedure tests the long term ageing Properties Of the complete CRT system. If the tube is cut down after the test i5 complete, glass and
11、screen effects may be seperated. Warning; Due to the high powers involved in these tests, there is the possibility of excessive X-ray levels. Suitable X-ray precautions should be taken while the tests are in progress. ii _. EIA TEPL05-15 88 3234600 00073b0 T = TEP10 5-15 Page 1 Glass Aqeinq Procedur
12、e i Discussion: This test is intended to test the ageing characteristics of CRT glass when subjected to high power densities. Power densities sufficient for ageing of the glass to be a signifigant problem are most commonly encountered in projection television, aircraft cockpit displays and similar h
13、igh power density CRTs. The dosage used in step 3 and the wavelengths measured in step 6 may be adjusted to fit the end use of a particular glass type. Since glass ageing is normally more of a problem at short wavelenths than at long wavelengths, glass to be used with blue or UV phosphors should be
14、checked especially carefully. Equipment Required: 1) Glass Transmission Unit 2) CRT Production Equipment 3) CRT Ageing station or chassis Procedure: i. Clean the glass sample according to the currently specified procedure. Do not screen or lacquer the glass. Aluminize the glass according to the curr
15、ently specified procedure. Finish the tube in the normal manner. 2) If you will age at a greater power density than 4mW/cmz, install liquid cooling if needed for the tube type. 3) Age the tube at the normal operating conditions until 4 Coulombs/cm2 has been accumulated. 4) Cut the tube down and remo
16、ve the aluminum from the inside of the face with caustic solution (5-10% NaH). 5) Measure the glass transmission at the specified wavelengths using unaged glass in the transmission unit as the 100% reference value. 6) Record the average transmission and transmission at any specific wavelengths of in
17、terest. A suggested form is attached. 7) Visually inspect the aged area for cloudiness or a “milky“ appearance. If any is visible, the glass is rejectable. Normal glass color after aging is a transparent brown. EIA TEPL05-15 88 m 3234600 00073bL L m TEPIOS-15 Typical Glass Aging Report This Lot of C
18、RT Glass is ACCEPTABLE/REJECTABLE for glass aging. Glass Manufacturer Data Attached (When available) Lat# Maunufacturer Drawing# Type Date Tested Tubes Made By Tube Numbers First Tube: On Aging Off Aging Aging Station Aging Conditions Transmission Measurements Instrument used 448nm Note: These wavel
19、engths are suitable for projection 544nm tube glass, other wave- 610nm suitable for other Comment lengths may be more applications - Note: Cloudy or milky appearance is cause for rejection Second Tube: On Aging Off Aging Aging Station Aging Conditions Transmission Measurements Instrument used 448nm
20、544nm 6lOnm Comment Note: Cloudy or milky appearance is cauce for rejection - EIA TEPLOS-15 8 323i.1600 O007362 3 P TEP105- 15 Page 3 II. Pre-aqeinq Procedure ais cus s ion : This procedure is presented separately from the long term ageing for two reasons. First, this gives a quick test to determine
21、 if tube ageing will be satisfactory. If a tube fails this test, it is almost certain to fail a long term ageing test. Second, if there is rapid initial ageing, it is difficult to measure accurately in a long term ageing rack set up to measure slaw luminance changes. Equipment: 1) 2) Procedure: 2) 3
22、) 4) 5) 6) 7) Test Set A non-contact luminance meter mounted on a tripod capable of measuring a small area on the tube. Example: Tektronix J-16 meter with lo luminance probe. Put the tube into the test set. Install liquid cooling if necessary. Set the tube up with a 3“ x 3“ (76.2 x 76.2mm) unblanked
23、 raster with 30kV anode voltage, 112 UA anode current. Note: the reduced raster size is used so the edge of the raster will be visible when the liquid cooling is used. It also serves to increase the power density of the test. Measure and record the luminance (Lo). Multiple readings may be made to in
24、crease accuracy. In order to get the 1% relative luminance accuracy this test requires, the luminance meter should not be disturbed between the initial. and final readings. Increase the current to 1OOOuA. Maintain 30kV. Observe the tube for 1 hour. Record any arcs, neck glow, aluminizing peel, emiss
25、ion slump or other problems. After 1 hour, turn the tube off and allow to cool to roam temperature for at least two hours. Do not remove the tube from the test set, adjust raster size or otherwise disturb the tube setup or the luminance meter. Note: The 1 hour period should be continuous, not broken
26、 up. Do not start the test unless sufficient time is available to complete the 1 hour. Set the tube up to 30 kV, 112pA and reread the luminance as in step 2 (Lp). i EIA TEPLOS-L5 88 3234b00 00073b3 5 TEPl.05-15 Page 4 Pre-Aqeinq Procedure (Continued) 8) The pre-age value is the average luminance rea
27、ding made after. the 1 hour period divided by the average luminance reading made before the 1 hour period (Lp/Lo), Since the ratio of these readings is typically 1.01 - .96, very small errors in set up of the tube, especially raster size, will make the measurement meaningless. That is the reason why
28、 the tube cannot be removed from the test set during the cool down period. 9) If the edge of the raster is readily visible after the test is complete as a line of demarcation between the aged and unaged area, the performance of the tube is considered relatively poor. 10) The pre-age value (Lp/Lo) ca
29、lculated in step 8 is the first point on the L/Lo vs. Q curve. A Q of .O62 Caulombs/cm2 is accumulated during this test. 11) If liquid cooling is not used on the tube, 500pA and 2 hours may be used in steps 5 and 6. For most phosphor systems this will give comparable results. EIA TEP105-15 88 m 3234
30、600 0007364 7 m * 3 TEP10 5- 15 Page 5 Lons Term Aqinq Procedure II1 A. Introduction Aging or browning is defined as the change in light output of a phosphor-CRT system as a function of time of operation of the CRT under given electrical conditions. The change in light output is generally a decrease
31、 in the long term, but can also in some cases be a short term increase, referred to as “bright burn“, which occurs during the early operation of the CRT, and preceeds the long term decrease. The light output changes involve the effects of glass, phosphor, screening methods, process variables, alumin
32、um layer, and electrical conditions such as current density nd accelerating voltage. For a given set of these processes and conditions, the aging or browning of the CRT system is given as a plot of fractional light output (L/Lo) vs. cumulative electron charge deposited in the screen (Q), measured in
33、 coulombs/cm2. For most phosphors, the light output vs. charge curve is independent of the current density during aging. (Ref: Extended Abstracts of the Electrochemical Society Vol. 87-2 1987 abstract #1242, Aging of Phosphors in Projection TV Tubes, T. Welker et.al.1 The fractional light output is
34、Lq/Lo, where Lq is light output after Q coulombs/cm2 and Lo is the initial light output. Both Lq and Lo are easured at the same position on the screen, with the same current density, *aster geometry , accelerating voltage, degree of beam focus, and face plate temperature, This ensures Lo and Lq are
35、measured at the same conditions of phosphor saturation with respect to charge density at the screen. B, Cl 1, Equipment Required 1) Ageing Station Note: Since ageing tests typically take weeks or months, the 2) Luminance meter, radiance meter or other appropriate light meter. 3) Glass Transmission U
36、nit ageing station used should have excelent long term stability and reliability. Procedure Install CRT to be tested in an appropriate chassis and produce an excited pattern with raster size and linearity, accelerating voltage, electron beam current, focus conditions, and ambient temperature such th
37、at the actual conditions of operation of the tube in its intended application are closely approximated. Mark the face of the tube in such a way that the light meter can measure the light output in a reproducible position or geometry in all measurements. If accelerated aging is used, with current den
38、sities increased during ageing compared to values during measurement, a five minute minimum cool down is used to return to test conditions. Pre-aging is recommended with accelerated aging. EIA TEPLOS-LS 88 3234600 O007365 9 8 9 TEP105-15 Page 6 C. Long Term Ageing Procedure (Continued) 2. Measure in
39、itial liqht output , raster dimensions, accelerating .- voltage, anode current, and start time. The first reading of light output should be taken as soon as possible after the test is started, preferably within a minute, so that the reading is taken while the screen is still at ambient temperatures.
40、 If pre-ageing was not used, this measurement will correspond to Lo. If preaging was used, this value will correspond to Lo multiplied by pre-age measurement. 3. Take light output readings as a function of time until the total accumulated coulombs/cm2 is sufficient to evaluate the behavior of the li
41、ght output in its intended application. 4. For each time at which ligh output, Lq, was measured, calculate Lq/Lo, where Lo is initial output. Calculate cumulative coulombs/cm2 at each time. Plot Lq/Lo (ordinate) vs. cumulative coulombs/cmz. This is the required curve. D. THERMAL EFFECTS 1. 2. 3. 4.
42、E. 1. 2. Since light output of the phosphor screen is a function of temperature of the screen, the early part of the curve obtained above includes temperature effects during the time that the tube temperature was rising from ambient to equilibrium. This effect can be taken into account as follows: A
43、fter the tube has been under test for a sufficient lensth of time it will have reached a state where its light output does not change measurably over a period of several hours. At this point it is convenient to make measurements on the thermal effects in the early part of the aging curve. This typic
44、ally occurs after 2-10 coulombs/cmz. Turn off tube and allow it to cool to ambient temperature (two hour minimum). Turn on the tube, using the same test conditions as used earlier. Measure light output (LI at intervals of a few minutes until light output has stabilized at its equilibrium value (Lt).
45、 Plot L/Lt vs. time or coulombs/cmA2. For each point on the early part of the original curve, except the point measured with the pre-ageing procedure, multiply the Lq/Lo value by the corresponding point on the L/Lt curve. This new value i5 the Lq/Lo value corrected for thermal effects. PRESENTATION OF DATA Plot Lq/Lo vs. Q. List all relevant test conditions, including phosphor used, screening conditions, accelerating voltage, focus voltage, raster geometry, and photometer position. If phosphor thermal properties are of interest, plot L/Lt vs Q or time. Include all relevant test conditions.
