US3865489A - On-line detection and measurement of contaminating gases during filling of gas display panels - Google Patents

On-line detection and measurement of contaminating gases during filling of gas display panels Download PDF

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Publication number
US3865489A
US3865489A US431812A US43181274A US3865489A US 3865489 A US3865489 A US 3865489A US 431812 A US431812 A US 431812A US 43181274 A US43181274 A US 43181274A US 3865489 A US3865489 A US 3865489A
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United States
Prior art keywords
gas
mixture
argon
decay
contaminating
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US431812A
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English (en)
Inventor
Melvin Klein
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International Business Machines Corp
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International Business Machines Corp
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Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Priority to US431812A priority Critical patent/US3865489A/en
Priority to FR7441914A priority patent/FR2257087B1/fr
Priority to DE19742459184 priority patent/DE2459184A1/de
Priority to GB5419874A priority patent/GB1446100A/en
Priority to JP50004503A priority patent/JPS50107989A/ja
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/66—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
    • G01N21/69—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence specially adapted for fluids, e.g. molten metal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/38—Cold-cathode tubes
    • H01J17/48—Cold-cathode tubes with more than one cathode or anode, e.g. sequence-discharge tube, counting tube, dekatron
    • H01J17/49—Display panels, e.g. with crossed electrodes, e.g. making use of direct current

Definitions

  • This invention relates to the field of gas display panels and, more particularly, to a method and apparatus for detecting and measuring contaminating gases in a gas mixture during the filling of such gas display panels on a production line.
  • a gas display panel is illuminated by electrically exciting a discharge in a Penning mixture of neon and argon gas.
  • the mixture is typically approximately 99.9 percent neon and 0.1 percent argon by partial pressures.
  • the Penning mixture may be defined as one in which the ionization potential of the added argon is less than the metastable potential of neon, the parent gas.
  • undesired contaminating or impurity gases such as nitrogen, water vapor and others, in concentrations exceeding, for example, parts per million, has a deleterious effect on the operation of the gas panel.
  • a group of gas panels is connected by their tubulations to ports on the manifold of a gas filling station, and the panels are carefully bakedout while being subjected to a high vacuum. Then, the panels are filled with the desired gas mixture at a specified pressure.
  • the gas mixture has previously been passed through various purifying devices to eliminate undesired contaminating gases which may be present in the purchased gas or in parts of the filling system. After the panels are filled, the tubulations are sealed off, and the panels are removed from the filling station.
  • the concentration of contaminating gases will be below a specified level chosen to guarantee correct operation of the panels.
  • possible leaks or other faults in the filling system, contaminated gas sources, or mishaps during the seal-off of one of the panels connected to the manifold can introduce unacceptable amounts of contaminating gases. It is important to detect such contamination before the panels are sealed off, because no repair or rework is possible once the panels have been sealed off. What is required, therefore, is a fast simple, on-line measurement of contaminating gas concentration in the gas mixture to allow the operator of the filling system to decide whether to seal off the panels or to troubleshoot them and repeat the filling procedure.
  • the term Penning mixture is well known in the art and may be defined as a mixture of two gases which exhibit the Penning effect or discharge.
  • the Penning effect or discharge may be defined as one which occurs in a mixture of two gases when the gas having the higher ionization potential has a metastable state with a potential higher than the ionization potential of the other gas.
  • the gas forming the larger portion of the mixture is referred to as the parent gas.
  • Typical Penning mixtures are formed by mixing neon (parent) with small quantities of argon, krypton and xenon; argon (parent) with krypton or xenon; or krypton (parent) with xenon.
  • a Penning mixture can be formed by adding mercury vapor to most parent gases.
  • the Penning mixture of neon and argon may contain from 0.01 to 10 percent of argon; see Determination of the Townsend Ionization Coefficient Alpha for Mixtures of Neon and Argon," A; A. Kruithof and F. M. Penning, Physica, Vol. 4, Page 430, 1937.
  • the object of this invention is to provide an improved method and apparatus for overcoming the above disadvantages of the prior art with respect to the on-line detection and measurement of contaminating gases during the filling of gas display panels.
  • a more specific object of this invention is to provide such a method and apparatus which utilizes the argon after-glow of a Penning discharge in a neon-argon mixture todetect and measure contaminating gases during filling of gas display panels.
  • the neon metastables can be de-excited by collisions with these molecules as well as by collision with argon atoms.
  • the result is a more rapid decay of the neon metastable concentration as'compared to that for the uncontaminated Penning mixture.
  • the process also can be followed by observation of the intensity of argon radiation as a function of time. Again, the decay of the argon radiation intensity is exponential.
  • the time constant of the decay is a function of the concentration of the contaminating gas. In other words, the after-glow of the argon is utilized to measure the concentration of contaminating gas in the Penning mixture.
  • FIG. 1 is a schematic diagram illustrating a preferred embodiment of the method and apparatus of this invention.
  • FIG. 2 is a graph showing a plot of the decay time constant of the after-glow argon radiation intensity in a Penning mixture of neon and argon versus the parts per million of contaminating air in the mixture.
  • FIG. 1 is a schematic block diagram illustrating the apparatus and method of this invention wherein the concentration of contaminating or impurity gases in a Penning mixture is measured using the principle described above.
  • a plurality of gas panels are connected via tubulations 12 to manifold 14 which in turn is connected to a filling station 16 containing a Penning mixture of neon and argon gas in the proportions of approximately 999 percent neon and 0.1 percent argon by partial pressures.
  • a pressure gauge 18 is also shown coupled to the manifold 14 to symbolize the fact that in practice a constant pressure is maintained during filling. Typically, this pressure is approximately 600 Torr.
  • test discharge cell 20 is also coupled to the gas manifold 14 via a conduit 22.
  • Test cell 20 consists of a glass tube 24 and two sealed-through metal electrodes 26 and 28.
  • the test cell 20 may be identical to a commercial neon tube in structure.
  • the test cell is excited by a train of voltage pulses 30 applied to the electrodes by a conventional pulse generator 31 which generates the exciting pulses at a repetition rate of approximately 2 KHz.
  • each pulse has a duration of approximately five microseconds and a peak voltage of approximately 300 volts.
  • the resultant light radiation from the excited test cell is transmitted to a conventional photomultiplier tube 32, such as an RCA C70042R, via a suitable optical coupling 34, such as lenses, fiber bundles, or a combination thereof.
  • a filter 36 is interposed between the test cell 20 and the photomultiplier 32 for selecting a suitable line of the argon after-glow radiation spectrum while excluding radiation from the neon or contaminating gases.
  • a suitable argon wavelength is 7633 Angstroms because it is well isolated from the neon lines.
  • the output from the photomultiplier 32 is a current pulse 38 having an exponential decay.
  • This current pulse is applied to a conventional logarithmic amplifier 40 whose output voltage 42 has a linear decay as a result of the application of the logarithmic response of the amplifier to the exponentially decaying input pulse.
  • the output of the amplifier 40 is applied to the deflection circuitry of a conventional oscilloscope 44 so that the output of the logarithmic amplifier is displayed on the face 46 of the oscilloscope.
  • the pulses 30 from pulse generator 31 are applied to the sweep circuitry of the oscilloscope, thereby synchronizing the pulse generator and the oscilloscope.
  • the face of the oscilloscope is provided with a simple calibration and scale so that one can directly observe the time constant of the linear decay of the argon after-glow radiation intensity, i.e., the argon radiation intensity which occurs after the termination of each exciting pulse.
  • the calibration of this system is accomplished by making measurments of the argon after-glow at the specified operating pressure and with the specified Penning mixture, but with the addition of known amounts of contaminating gas by means of a calibrated leak. One then prepares a calibration curve showing the argon after-glow or radiation intensity decay time constant as a function of the contaminating gas content. Since the most likely contaminating or impurity gas would be air resulting from faults or leaks in the filling system, the preferred calibration would be one made with air.
  • FIG. 2 is an actual calibration graph for a Penning mixture consisting of 99.09 percent neon and 0.01 percent argon at a filling pressure of 600 Torr.
  • the plot is on a double logarithmic scale for which the ordinate indicates the argon after-glow decay time constant in microseconds and the abscissa the parts per million of air.
  • the method and system illustrated in FIG. 1 is capable of measuring air concentrations in the range from 10 to parts per million.
  • the decay time constant is read from the face of the oscilloscope 44 and the air concentration is then determined by reference to the graph in FIG. 2.
  • the novel features of this system are: (a) the use of the effect of contaminating gases on the metastable decay rate of the parent gas in a Penning mixture to provide a direct indication of the amount of contaminating gas present; (b) the use of a pulsed discharge in the Penning mixture to permit observation of metastable decay subsequent to the electrical excitation of the gas for the purpose of measuring contaminating gas concentrations; and (c) an apparatus and method that provide a simple direct read-out of a parameter directly related to the contaminating gas concentration.
  • the argon after-glow intensity radiation is measured, i.e., the measurement of the argon radiation is made after the electrical excitation of the test discharge cell 20 has been removed, whereby the measurement is substantially independent of the details of the electrical excitation;
  • measurement is both fast and direct reading;
  • the apparatus is simple and rugged and requires a minimum of operating adjustment; and d) the measuring method and apparatus are well suited to online application in a manufacturing environment.
  • An apparatus for detecting the presence of a contaminating gas in a Penning mixture of a first gas and a second gas, the first gas having a higher ionization potential than said second gas and also having a metastable state with a potential higher than the ionization potential of said second gas, comprising:
  • a. electrical pulse generating means for applying to a optic means is an oscilloscope synchronized with said pulse generating means, and the time rate of decay is exponential, and further comprising a logarithmic amplifier connected between said photomultiplier tube and said oscilloscope so that said oscilloscope produces a linear display of the time constant of the decay of the radiation intensity.
  • the apparatus defined in claim 8 further comprising optical filter means for transmitting to said photomultiplier tube only a selected characteristic wavelength of the radiation of said second gas.
  • the apparatus as defined in claim 7 further comprising means for supplying the Penning mixture under a predetermined pressure to a gas panel, and means for extracting said sample from the supplied gas.
  • the apparatus as defined in claim 10 further comprising a test discharge cell for holding the extracted sample, and means for electrically connecting said cell to said pulse generating means.

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  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Immunology (AREA)
  • Physics & Mathematics (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Combustion & Propulsion (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
US431812A 1974-01-08 1974-01-08 On-line detection and measurement of contaminating gases during filling of gas display panels Expired - Lifetime US3865489A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US431812A US3865489A (en) 1974-01-08 1974-01-08 On-line detection and measurement of contaminating gases during filling of gas display panels
FR7441914A FR2257087B1 (zh) 1974-01-08 1974-11-22
DE19742459184 DE2459184A1 (de) 1974-01-08 1974-12-14 Verfahren zur ermittlung schaedlicher gasbestandteile in gasentladungsbildschirmbauelementen
GB5419874A GB1446100A (en) 1974-01-08 1974-12-16 Testing for impurities in penning mixtures
JP50004503A JPS50107989A (zh) 1974-01-08 1975-01-08

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US431812A US3865489A (en) 1974-01-08 1974-01-08 On-line detection and measurement of contaminating gases during filling of gas display panels

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JP (1) JPS50107989A (zh)
DE (1) DE2459184A1 (zh)
FR (1) FR2257087B1 (zh)
GB (1) GB1446100A (zh)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0739025A2 (en) * 1995-04-19 1996-10-23 Tektronix, Inc. Addressing structure using ionizable gaseous mixture having decreased decay time
EP0780874A3 (en) * 1995-12-21 1998-12-09 Tektronix, Inc. Addressing structure using ionizable gaseous mixtures having multiple ionizable components

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6368175B1 (en) † 1998-03-16 2002-04-09 Matsushita Electric Industrial Co., Ltd. Discharge lamp and method of producing the same
JP4679389B2 (ja) * 2006-02-20 2011-04-27 株式会社日立ハイテクノロジーズ イオン化エネルギーの低い試料を検出する検出器及び分析装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA568974A (en) * 1959-01-13 The British Oxygen Canada Limited Photoelectric gas impurity detector

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA568974A (en) * 1959-01-13 The British Oxygen Canada Limited Photoelectric gas impurity detector

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Proceedings of the Fifth International Conference on Ionization Phenomena in Gases, Vol. II, edited by H. Maecker, North-Holland Publishing Co., Amsterdam, 1962, pp. 1356-1358 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0739025A2 (en) * 1995-04-19 1996-10-23 Tektronix, Inc. Addressing structure using ionizable gaseous mixture having decreased decay time
EP0739025A3 (en) * 1995-04-19 1998-12-09 Tektronix, Inc. Addressing structure using ionizable gaseous mixture having decreased decay time
EP0780874A3 (en) * 1995-12-21 1998-12-09 Tektronix, Inc. Addressing structure using ionizable gaseous mixtures having multiple ionizable components

Also Published As

Publication number Publication date
FR2257087A1 (zh) 1975-08-01
JPS50107989A (zh) 1975-08-25
DE2459184A1 (de) 1975-07-10
FR2257087B1 (zh) 1976-10-22
GB1446100A (en) 1976-08-11

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