1、- - EIA 502-A 89 W 3234600 0071943 2 = L. -3 tiGEEis ANSI/ EIA-502-A-198 9 APPROVED: February 9, 1989 O a I Cu O ln I w 0 EIA STANDARD Recommended Practice for Measurement of X-Radiation from Non-Raster-Scanned -Direct-View Cathode Ray Tubes EIA-502-A MARCH 1989 ELECTRONIC INDUSTRIES ASSOCIATION ENG
2、INEERING DEPARTMENT _ EIA 502-A Bq 3234600 0073944 4 . NOTICE EIA Engineering Standards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting th
3、e purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards and Publications shall not in any respect preclude any member or non-member of EIA from manufacturing or selling products not conforming to such Standards and Publication
4、s, nor shall the existence of such Standards and Publications preclude their voluntary use by those other than EIA members, 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 adop
5、tion may involve patents on articles, materials, or processes. By such action, EIA does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Recommended Standard or Publication. This EIA Standard is considered to have international standard
6、ization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the EIA standard and the IEC document can be made. This Standard does not purport to address all safety problems associated with its use or all applicable
7、regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. Copyright 1989 Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 1722 E
8、ye Street, N.W. Washington, D.C. 20006 PRICE: $10.00 All rights reserved Printed in U.S.A. .- EIA 502-A 9 3234b00 0073945 b a EIA-502-A RECOMMENDED PRACTICE FOR MEASUREMENT OF X-RADIATION FROM NON-RASTER-SCANNED DIRECT-VIEW CATHODE RAY TUBES TABLE OF CONTENTS Parasraph 1.0 2.0 3.0 4.0 5.0 6.0 7.0 PU
9、RPOSE 1.1 Scope APPARATUS 2.1 X-Radiation Detection Instruments 2.2 Test Equipment CALIBRATION TEST CONDITIONS 4.1 Tube Position 4.2 External Components 4.3 Warm-up 4.4 Display 4.5 Reference Anode Current 4.6 Limiting Conditions SEARCH PROCEDURE 5.1 Initial Display Size and Position 5.2 Tube Electri
10、cal Conditions 5.3 Search Areas 5.4 Final Display Size and Position MEASUREMENT PROCEDURE 6.1 Principal X-Radiation Measuring 6.2 Hypothetical Cabinet 6.3 Measurement REPORT instrument Positioning Paqe 1 1 2 2 3 4 4 6 6 7 7 8 8 8 9 9 9-10 EIA 502-A 89 E 3234600 007194b 8 TABLE OF CONTENT (Contd) Pas
11、e FIGURES : 1A: Display Size and Position A (Rectangular-Screen CRT) 1B: Display Size and Position A (Circular-Screen CRT) 2A: Display Positions (Bl, B2, B3, B4) (Rectangular-Screen CRT) 2B: Display Position (Bl, B2, B3, B4) (Circular- Screen CRT) 3: Hypothetical Cabinet aa 12 13 a4 15 ELA 502-A 89
12、3234b00 0073947 T EIA-5 O 2 -A Page 1 RECOMMENDED PRACTICE FOR MEASUREMENT OF X-RADIATION FROM NON-RASTER-SCANNED DIRECT-VIEW CATHODE RAY TUBES (From EIA Standards Proposal No. 2149, formulated under the cognizance of EIA JT-32 Committee on Electron Tube Safety.) 1.0 PURPOSE The purpose of this Stan
13、dard is to obtain the x-radiation characteristics of non-raster-scanned direct-view data display cathode ray tubes in order to predict the levels emitted by tubes when electrical characteristics of the application are known. 1.1 Scope This test method applies to the measurement of x-radiation emitte
14、d from non-raster-scanned direct-view cathode ray tubes. For some applications the test procedures described in Recommended Standard EIA-501, IlRecommended Practice for the Measurement of X-Radiation from Raster-Scanned Direct-View Data Display Cathode Ray Tubes,“ or EIA-503, IIRecommended Practice
15、for Measurement of X-Radiation from Direct-View Television Picture Tubes, It may be more appropriately used than those described herein. CAUTION SAFETY CONSIDERATIONS Measuring instruments should be properly grounded. Caution should be taken to avoid shock hazard, particularly in the vicinity of the
16、 anode connection and the voltage metering systems. Safety equipment should be worn at times during the measurement procedure. X-ray film badges should be worn in accordance with established plant safety practices for monitoring radiation dosage. I EIA 502-A 9 m 3234600 L187II948 II m EIA- 5 02 -A P
17、age 2 2.0 APPARATUS 2.1 X-Radiation Detection Instruments 2.1.1 Search Instruments A rapid response instrument, designed to detect low energy x-radiation, is recommended te locate the position of instruments such as the Texas Nuclear Model 2652; the Johnson TV X-1; or the Victoreen Model 491). Thin
18、window ion chamber survey meters may also be used. See EIA-Consumer Products Engineering Bulletin No. 3, tvMeasurement Instrumentation for X-Radiation from Television Receiverstt. maximum radiation. (Examples: G-M tube 2.1.2 X-Radiation Measuring Instrument The principal x-radiation measuring instru
19、ment shall comply with the requirements of Title 21, Code sf Federal Regulations (CFR), Chapter I, Subchapter J, Section 1020.10, subparagraph (6)- (2), and with EIA Consumer Products Engineering Bulletin No. 3 (CPEB-3). The instrument shall provide x-radiation measurements (mR/h) in the range of th
20、e applicable limit. The x-radiation sensitive volume shall have a cross section parallel to the external surface of the hypothetical cabinet with an area of 10 cm2 and no dimension larger than 5 cm . Measurements deviations due te instruments imprecision, energy dependence and other sources of error
21、 shall be commensurate with current instrument art. An example of an instrument which fulfills these requirements is the Vistoreen 440 RP/C. EIA 502-A 89 m 3234b00 0073949 3 m EIA- 5 O 2 -A Page 3 Measurements with instruments having other areas must be corrected for spatial non-uniformity of the x-
22、radiation field to obtain the exposure rate averaged over a 10 cm2 area. Note : A larger area detector may be used, provided that the field is determined to be uniform over its aperture. Examples: Victoreen 440 RF, Victoreen 208A, Riverdale Precision TV-150. 2.2 Test Equipment Stable electronic cond
23、itions must be provided for the operation of the tube under test and to measure anode voltage and current. 2.2.1 Anode Voltage Metering System The recommended anode voltage metering system incorporates a very stable and accurate high voltage divider and voltmeter with an overall accuracy of these tu
24、bes may require a unique search technique. 5.1 Initial Display Size and Position The display size and position shall be adjusted to just fill the entire display area at the major and minor axes. (See Figure 1A and 1B.) EIA 502-A 89 3234600 0073953 5 EIA-5 02 -A Page 7 5.2 Tube Electrical Conditions
25、Holding the anode current constant at the reference value, increase the overall accelerating potential to a value which results in readily discernable x-radiation, or 1 1/2 times the maximum rated overall accelerating voltage, whichever condition is reached first. 5.3 Search Areas Both on-screen and
26、 off-screen areas should be searched as described in paragraphs 5.3.1 and 5.3.2. 5.3.1 Search, On-Screen Display Using the initial display conditions, position the detector for maximum indicated x-radiation for both the tube faceplate and the hypothetical cabinet. For each of these detector position
27、s change the final display according to paragraph 5.4. 5.3.2 Search, Off-Screen Display Position the initial display for overscan conditions such that the display edge strikes the neck, deflection plate, or other limiting structure, see Figures 2A and 2B. Alternatively, the deflection voltages may b
28、e doubled to obtain overscan conditions. In either case, the overall accelerating potential or anode current may need increasing to maintain a readily discernable detector indication. Using the overscan display conditions, position the detector for maximum indicated x-radiation; for both the tube fa
29、ceplate and the hypothetical cabinet. For each of these detector positions, change to the final display according to paragraph 5.4. EIA 502-A 89 m 3234600 0073954 7 W EIA-5 O 2 -A Page 8 5.4 Final Display Size and Position Maintaining the detector position determined in paragraphs 5.3.1 or 5.3.2, re
30、duce one display dimension, either the vertical or horizontal, to 2.5 cm or less, resulting in a band 25 cm (or less) wide. Maximize the detector indication by re-positioning the resultant display along the axis which was reduced. Next, reduce the other display dimension to 2.5 cm or less, resulting
31、 in a 2.5 cm (or less) rectangular display. Again, maximum the detector indication by re-positioning the resultant display along the axis which was reduced. In some cases, it may be advantageous to confirm off-screen position and display size by monitoring the deflection voltages. 6.0 MEASUREMENT PR
32、OCEDURE 6.1 Principal X-Radiation Measuring Instrument Positioning 6.1.1 Replace the search instrument with the principal x-radiation measuring instrument. Adjust the instrument position for maximum x-radiation indication. Readjust the display position for maximum x-radiation indication. 6.1.2 X-rad
33、iation shall be measured with the effective center of the principal measuring instrument 5 cm from the surface of the tube faceplate or hypothetical cabinet. (When the plastic spacers of the Victoreen 440 RF/C survey meter are in contact with a surface, the distance from that surface to the effectiv
34、e center of the detector is 5 cm.) 6.1.3 The center of the principal x-radiation measuring instrument aperature must be positioned at least to the corners of the hypothetical cabinet. EIA 502-A 89 3234600 0071955 9 EIA-5 02-A Page 9 6.1.4 The face of the principal x-radiation measuring instrument sh
35、all always be parallel to the respective plane of the hypothetical cabinet or to the tube exposed surfaces, as appropriate. 6.2 Hypothetical Cabinet The hypothetical cabinet shall be according to Figure 3. The distance from the cabinet to the tube is 2.5 cm . 6.3 Measurement Adjust the overall accel
36、erating potential and anode current to the desired values and measure the x-radiation. 7.0 REPORT 7.1 Origin - Date - Observers Name - Laboratory - Procedure Used. 7.2 The following tube information shall be recorded: a) Tube Identification b) Reference Anode Current c) Rated Overall Accelerated Pot
37、ential. 7.3 External shielding and components, including deflection yokes, if used, shall be specified together with their critical dimensions and their location on the tube. 7.4 The following information shall be on record: a) Manufacturer b) Serial Number c) Accuracy Specification d) Correction Fa
38、ctors, if applicable EIA 502-A 89 3234600 007L5b O M , EIA-5 02 -A Page 10 e) Calibration Date f) Any other pertinent information to qualify the results. This information is required for at least: 1) The anode voltage metering source 2) The anode current metering source 3) The principal x-radiation
39、measuring instrument. 7.5 The following data shall be recorded: a) Measurement Location b) Display Location c) Gun or Guns Used d) Anode Current e) Overall Accelerating Potential f) X-Radiation Reading 9) Background Reading EIA 502-A 9 m 3234600 0073957 2 m c , II I EIA-502 -A Page 11 f I II I II I
40、11 Y FIGURE 1A DISPLAY SIZE AND POSITION (A) (RECTANGULAR SCREEN CRT) EIA-5 02 -A Page 12 Il I I II I -1 II Il FIGURE 1B DISPLAY SIZE AND POSITION (A) (CIRCULAR-SCREEN CRT) EIA 502-A 89 m 3234600 0073959 b m EIA-5 O 2 -A Page 13 Position B1 Position 82 r I I I I I I t I I I I - I FIGURE 2A DISPLAY P
41、OSITIONS (Bl, B2, B3, B4) (RECTANGULAR-SCREEN CRT) EIA-5 02 -A Page 14 Position 81 Position 82 Posftion B3. Position BO FIGURE 2B DISPLAY POSITIONS (Bl, B2, B3, B4) (CIRCULAR-SCREEN CRT) I I l 1 I -I I I I I I I I I I 1: I II EIA 502-A 89 m 3234600 007LbL 4 m i e 0 EIA-502-A Page 15 FIGURE 3 HYPOTHETICAL CABINET
