ECA EIA-503-A-1990 Recommended Practice for the Measurement of X-Radiation from Direct-View Television Picture Tubes (Errata 03 06 2001).pdf

1、Electronic Industries Alliance 2500 Wilson Boulevard. Arlington. Virginia 22201 -3834 703-907-7500 fax 703-907-7501 www.eia.org March 6, 2001 ERRATA TO: Recipients of the February 2001 Reaffirmed ANWEIA-503-A “Recommended Practice for the Measurement of X-Radiation from Direct-View Television Pictur

2、e Tubes“ NOTE: Please replace pages 5 and 6 with the pages attached. Part of the text on page 6, Section 6.5.1 did not print after converting from Word Perfect to Word format when the document was reaffirmed. We are sorry for any inconvenience this may have caused. Sincerely, Phil. CdtofJ Publicatio

3、ns Office Technology Strategy the TV X-1; or the Model 491. Thin window ion chamber survey meter may also be used. See EL4 Consumer Products Engineering Bulletin No. 3 “Measurement Instrumentation for X-Radiation from Television Receivers“. 3.1.2 X-Radiation Measuring Instrument The principal x-radi

4、ation measuring instrument shall comply with the requirements of Title 21, Code of Federal Regulations (CFR), Chapter I, Subchapter J, Section 1020.10, subparagraph (c)-(2), and with EL4 Consumer Products Engineering Bulletin No. 3. The instrument shall provide x-radiation measurements (mR/h) in the

5、 range of the applicable limit. The x-radiation sensitive volume shall have a cross-section parallel to the external surface of the hypothetical cabinet of 10 CII? and no dimension larger than 5 cm. Measurement deviations due to instrument imprecision, energy dependence and other sources of error sh

6、d be commensurate with the current instrument art. An example of an instrument that fulfills these requirements is the 440 RF/C. Measurement with instruments having other areas must be corrected for spatial non-uniformity of the radiation field to obtain the exposure rate averaged over a 10 cm2 area

7、. NOTE: A larger area detector may be used, provided that the field is determined to be uniform over its aperture. Examples: 440 RF, A and TV-150. 3.2 Test Equipment Stabie electronic conditions must be provided for the operation of the tube under test and to measure anode voltage and current. 3.2.1

8、 Anode Voltage Metering System The recommended anode voltage metering system incorporates a very stable and accurate high voltage divider and voltmeter with an overail accuracy of 0.1% and a digital readout using at least four signifcant figures, having a sensitivity of at least 0.01 kV. (The effect

9、 of the overall accelerating potential on the x-radiation characteristics is such that the x-radiation exposure rate could double for each 1 kV change of accelerator potentia thereby making accurate voltage measurements desirable.) If the recommended accuracy of the measurement system cannot be achi

10、eved, the inaccuracy shall be accounted for by reducing the recorded voltage reading by the maximum possible measurement deviation. EIA 503-A SO- 3234600 0073968 7 ! 5.1 Tube Position 4 I 5.2 External Components Q I 5.3 Warm-up EIA-503-A Page 3 3.2.2 Anode Current Metering System The recommended cur

11、rent metering system incorporates an overall accuracy of & 1%. (The effect of the anode current on the x-radiation characteristics is that the x-radiation exposure rate is directly proportional to the anode current.) if the recommended accuracy of the anode current measurement system cannot be achie

12、ved, the inaccuracy shall be accounted for by reducing the recorded current reading by the maximum possible measurement deviation. Power Supply for the Overall Accelerating Potential The recommended power supply for the overall accelerating potential incorporates a stabaty of 0.05%. (The effects of

13、the overall accelerating potential on the x-radiation characteristics is in accordance with paragraph 3.2.1, thereby making a stable power supply desirable.) If the recommended stability of the power supply cannot be achieved, the variation shall be accounted for by recording the lowest voltage read

14、ing during a specific x-radiation measurement. 3.2.3 3.2.4 Anode Connector Assembly See paragraphs 6.2 and 6.3. 4. CALIBRATION 4.1 The measuring instrument shall be calibrated by exposure to a uniform x-ray field having an exposure rate and energy representative of those to be measured. 4.2 The cali

15、bration shall be traceable to the National Institute of Standards and Technology (NIST). 5. TEST CONDITIONS The tube under test shall be positioned relative to the test equipment so that measurements may be made as specified in paragraph 6.0. External components normally mounted on the tube may be i

16、n place while obtaining x-radiation characteristics. (External components may include deflection yokes, aiignment coils, mounting hardware, implosion protection mechanisms, etc.) A warm-up period shall be provided for both the tube and test equipment in order to obtain stable operating conditions be

17、fore proceeding with the measurement. Anode current shali not vary or drift more than & 1% while measurements are being made. 5.4 Display 5.4.1 Focus The tube under test shd be operated at optimum focus. EIA 503-A 90 3234b00 007L9b9 9 EIA-503-A Page 4 5.4.2 Blanking The tube shall be operated with d

18、c voltages which result in an unblanked raster. 5.4.3 Multiple Guns Multiple gun tubes may be operated using only one gun. 5.4.4 Raster Geometry The horizontal and vertical scan controls shall be adjusted so that the raster width and height coincide with the screen width and height. The linearity of

19、 the scan shall be checked and adjusted with a crosshatch pattern such that the distance between crosshatch lines measured along the major and minor axes shall be within +. 10% of the corresponding measurements at the center of the screen. The radius of curvature of all four (4) raster sides shall n

20、ot be less than 200 cm. The horizontal and vertical raster dimensions shall then be increased by 10% while maintaining the established linearity. 6. PROCEDURE The x-radiation exposure rate shall be measured as described below at the location of maximum intensity. The background radiation shall be ve

21、rified at the test position and corrections applied to the observed data as required. 6.1 Radiation from the Tube Face The radiation from the tube face shall be measured with the effective center of the detector 5 cm from the surface of the tube. NOTE: When the plastic spacers on the 440 RF/C Survey

22、 Meter are in contact with the tube face or the surface of the hypothetical cabinet, the distance from the surface to the effective center of the detector is 5 cm. The measured area of the tube face must be extended past the extremities of the actual faceplate to completely enclose the effective vol

23、ume of the hypothetical cabinet described in paragraph 6.4. This extension of the tube face is achieved by hypothetically extending the major spherical curvature of the front face of the tube to the top, bottom and side surface of the hypothetical cabinet. The measuring instrument may be placed anyw

24、here over the tube face or over the hypothetical extension of it, provided that the center of the detectors front face does not overlap the top, bottom or sides of the hypothetical cabinet. 6.2 Radiation Emitted from the Funnel Portion of the Entire Tube (Exclusive of the Anode Contact and Tube Face

25、) Radiation emitted from the funnel portion of the entire tube (exclusive of the anode contact and tube face) shall be measured with the effective center of the detector 5 cm from the surface of the hypothetical, non-absorbing cabinet that is described in paragraph 6.4 and shown in Figure 2. The mea

26、suring instrument shall be positioned for maximum exposure rate with the front face of the detector parallel to the surface of the cabinet. The measuring instrument may be placed anywhere over the surfaces of the hypothetical cabinet described in paragraph 6.4, provided that the center of the detect

27、ors front face does not overlap the outer edges of that surface of the hypothetical cabinet that is being measured. The anode contact shall be covered with a 2.5 cm diameter attenuating shield having a minimum absorption equivalent to 0.25 mm of lead and shall be concentric with the anode contact, a

28、s shown in Figure 3. EIA 503-A 90 W 3234b00 0073970 5 W EIA-503-A Page 5 6.2.1 Neck Radiation High voltage breakdown may occur at the electron gun under the stress of extremely high anode voltage. The resultant arcing or leakage, or both, may cause spurious x-radiation, which is independent of beam

29、current, to emanate through the glass neck of the picture tube. When making measurements at anode voltage above the maximum rating of the tube, and it is desired to determine the exposure rate resulting from the beam current only, the x-radiation from the neck of the tube should be shielded from the

30、 survey meter. 6.3 Radiation Emitted Through the Anode Contact Radiation emitted through the anode contact shall be measured with the effective center of the detector 5 cm from the surface of the hypothetical cabinet. (a) Electrical connection to the anode contact shall be made with a non-attenuatin

31、g wire connector shown in Figure 1, and ) all of the glass surface of the anode contact side of the funnel portion (including the frit seal area) shall be covered with an apertured shield of 6 mm maximum thickness, spaced a maximum of 3 mm from the funnel surface at the anode contact. A 2.5 cm diame

32、ter hole in the shield is centered around the anode contact. The minimum x-ray absorption of the shield shall be equivalent to at least 0.25 mm of lead. 6.4 Hypothetical Cabinet The hypothetical cabinet is shown in Figure 2, the sides of the hypothetical cabmet shall be 2.5 cm from the outside surfa

33、ce of the tube (excluding the extra thickness of any applied safety system, such as the tension band) at the ends of the major and minor axes of the face. The back shall be formed in part by a vertical circular surface of 8.5 cm diameter concentric with the axis through the neck of the tube. . This

34、circular surface is to be located 2.5 cm behind the published maximum protrusion of the base of the tube, which is to be measured relative to the center of the front face of the tube. The rear circular surface of the hypothetical cabinet is then at a fixed distance behind the front face of the tube

35、(for any given tube type), the actual distance being the maximum published overall length of the tube plus 2.5 cm. From the outer circumference of this circular surface, a concenttic conical surface is to extend forward at 49 to the tube axis until the diameter of the conical section is increased to

36、 28.5 cm. A vertical plane is then constructed radiating out from this maximum diameter of the cone, to form the remainder of the back of the cabinet as shown in Figure 2A. Exceptions: The conical section will be completely removed for all tube sizes with a minimum registered screen diagonal of less

37、 than 21.5 cm, and the back of the cabinet wiil be a flat vertical surface located 2.5 cm behind the published maximum protrusion of the base of the tube as shown in Figure 2C. For all other sizes, where the resultant cabinet height is less than 28.5 cm, the maximum diameter of the conical section c

38、oincides with the maximum height of the cabinet. The vertical plane forming the remainder of the back of the cabinet is then constructed radiating from the maximum diameter of this shortened conical section as shown in Figure 2B. For convenience in locating the x-radiation search and measuring instr

39、uments with respect to the hypothetical surfaces, a box, or parts of a box, of the size specified may be constructed. However, while measurements are made in the vicinity of the maximum diameter of the conical section of the back of the cabinet, either the flat surface radiating from the maximum dia

40、meter of the cone, or the conical section will have to be removed to allow the x-radiation measuring instrument to be placed on any part of that surface without hindrance from the 0 - _ other parts of the box. O EIA 503-A 90 3234600 0073973 7 EIA-503-A Page 6 The constructed box, or parts of the box

41、, should be of a low absorbing material to prevent loss of measurement sensitivity. Unless the box is removed while measurements are being made, a correction factor must be determined over the voltage range used for each meter location on the box being used and the x-radiation data adjusted accordin

42、gly. 6.5 Reading Technique 6.5.1 Model 440 RF/C - it is recommended that the 0-1 scale not be used. The measurement period should not be less than 30 seconds. The lowest reading during the measurement period should be recorded, ignoring sporadic downscale pulses. Background should be determined usin

43、g the same technique. 6.5.2 During the test exposure period, the anode voltage and current shali be constantly monitored and the lowest observed values of each recorded. 7. REPORT 7.1 Origin - Date - Observers Name - Laboratory - Procedure Used 7.2 Tube Identification External shielding and componen

44、ts, including deflection yokes, if used, shall be specified together with their critical dimensions and their location on the tube. 7.3 The foilowing equipment information shd be on record: - Manufacturer - Serial Number - Accuracy Specification - Correction Factors, if applicable - Calibration Date

45、 - Calibration Source and Accuracy - Any other pertinent information to qualify the results. The foilowing information is required for at least: - The anode voltage metering source. - The anode current metering source. - The principal x-radiation measuring instrument. EIA 503-A 90 W 3234600 0071972

46、9 L e 7.4 The following data shall be recorded - Measurement Location - Gun or Guns Used - Anode Current - Overall Accelerating Potential - X-Radiation Reading - Background Reading. EIA-503-A Page 7 EM-503-A . Page 8 EIA 503-A 70 m 3234600 0071773 O m FIGURE 1 DIAGRAM SHOWING CONSTRUCTION AND CONNEC

47、TION OF NON-ATTENUATING WIRE CONNECTOR EIA 503-A 90 m 3234600 0073974 2 m 1 frone I Vir HYPOTHETICAL CABINET DIMENSIONS FIGURE 2A EIA-503-A Page 9 LARGE CRTs ( 23.5 cm BULB HEIGHT) 2.h 4 i- l Prone I VIN .ur FIGURE 2B SW CRTs (93.5 cm BULB HEIGHT 221.5 cm SCREEN DIAGONAL) NOTE: L = maximum published

48、 overall length (Figures 2A, 2B and 2C) EIA 503-A 90 W 3234600 0073975 4 = EIA-503-A Page 10 li JI i i p: I! I “I- - FIGURE 2C VERY SMALL CRTs (c 21.5 cm SCREEN DIAGONAL) Shield - Hin. Absorption to 0.25 mm Lead 3 mm max. Anode Lead (See Fig. i ) Funnel Class Anode Contact Centering Means FIGURE 3 D

49、ETAIL OF ANODE CONNECTOR AND SHIELD EIA 503-A 40 m 3234600 007197b b m i EIA-503-A Page A-1 APPENDIX A DETERMINATION OF AITENUATION FACTOR OF ANODE CONNECTORS A. Procedure A.l This procedure is the same as that in paragraph 6.3 except that the anode connector to be measured is used instead of the non-attenuating wire connector. The location of the maximum intensity of radiation should be determined by probing, since it may differ from that found in paragraph 6.3 depending upon the connector design. With certain anode connector designs, the location and magnitude of maximum int