US3072825A - Device having a glow-discharge tube and glow-discharge tube intended for such device - Google Patents

Description

Jan. 8, 1963 s. M. FROU E'Al. 72, 5

DEVICE HAVING A GLOW-DISCHARG BE AND GLOW-DISCHARGE TUBE INT VICE ENDED F0 UCH DE Filed Nov. 14, 1960 2 Sheets-Sheet 1 INVENTOR SIMON FROUHS JAN SE LING AGT Jan. 8, 1963 S. M. FROUWS ETA]. DEVICE HAVING A GLOW-DISCHARGE TUBE AND GLOW-DISCHARGE TUBE INTENDED FOR SUCH DEVICE Filed NOV. 14, 1960 2. Sheets-Sheet 2 INVENTOR SIMON M.FROUUS JAN HORSEQING 3,072,825 DEVICE HAVING A GLOW-DISCHARGE TUBE AND GLOW-DISCHARGE TUBE INTENDED FOR SUCH DEVICE 7 Simon Mari Frouws and Jan Horseling, Eindhoven, Netherlands, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Nov. 14, 1960, Ser. No. 69,109 Claims priority, application Netherlands Dec. 8, 1959 4 Claims. (Cl. 315269) This invention relates to devices having a glow-discharge tube containing a cold non-activated cathode and an igniting anode near the cathode, the anode being substantially surrounded by a screen. It also relates to glow-discharge tubes intended for such devices.

Glow-discharge tubes are already known in which the anode screen is connected to the cathode through a highohmic resistor and wherein due to the small distance between the anode'screen and the anode, which is no more than a few times the free length of the path of the electrons in the filling gas of the tube, only a very weak discharge suflicient for suppressing delays in ignition can occur between the anode and the said screen. Since the anode screen is connected to the cathode, such a tube is not suitable for alternating voltage between the main electrodes.

Tubes are also known in which the potential applied to the anode screen is not constant and wherein steps are taken for suppressing leakage currents to the anode screen, for example by preventing the occurrence of atomised layers on the insulator supporting the screen. Such tubes are suitable for alternating voltage between the main .electrodes. In order to obtain sufiicient voltage stability of the tube in the forward direction, the

However, in order to derive a negative potential for the igniting anode from. the mains, it is necessary to interpose a transformer.

An object of the invention is to provide a device having a glow-discharge tube in which ordinary mains voltages with the voltage variations occurring therein can be used between the anode and the cathode, without objection, whilst nevertheless sufiicient sensitivity to ignition by means of a positive igniting anode can be obtained.

According to the invention in a device having a glowdischarge tube containing a cold non-activated cathode and an igniting anode near the cathode and'wherein the anode is substantially surrounded by a screen a second screen electrode is provided outside the anode screen and connected through a high-ohmic resistor to the cathode lead, whereas the anode screen is connected through a high-ohmic resistor to the anode lead, at least one of the two screens having a projection directed towards the other screen so that for the alternating operating voltage between the main electrodes a Weak discharge occurs between the two screens at a distance from the main discharge path such that delays in ignition in the discharge path between the igniting anode and the cathode can be prevented, but decreases in igniting voltage in the main discharge path in one of the two directions do not occur.

Due to the high-ohmic resistors through which the screens are connected to the main electrodes and the guard discharge which occurs between the two screens, a voltage distribution between the anode, cathode and two screens is brought about in the tube to enhance the voltage stability thereof.

Preferably, in a tube intended for a device according to the invention, the anode screen is so arranged relative Patented Jan. 8, 1963 to the anode that straight lines which do not intersect the screen can be drawn only between a portion of the surface of the cathode and the anode, whereas such lines cannot be drawn at all between the anode and that portion of the cathode to which the auxiliary discharge applies, or between the anode and the igniting anode, in this case, the auxiliary discharge between the two screens preferably takes place on that side of the anode screen which is remote as far as possible from the aperture for passing the main discharge.

In order that the invention maybe readily carried into eifect, it will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawings, in which:

FIGURE 1 is an axial section of the bulb of a discharge tube with the electrodes viewed from the side;

FIGURE 2 is a plan view of the electrodes;

FIGURES 3 and 4 show two sections taken along the lines IIIIII and IV--IV of FIGURE 2, and

FIGURE 5 shows a simple circuit arrangement.

Referring now to FIGURES l to 4, a bulb 2 is sealed to a base 1 of the tube. A cathode 3 consists of a buckled molybdenum sheet which is secured to three supporting wires. An anode 4, which is made of nickel, is wire-shaped and surrounded by an anode screen 5. The cathode 3 has a sharply-pointed projection 6 and opposite thereto is an auxiliary anode 7 which is made of molybdenum strip. The anode screen 5 is surrounded by a buckled screen 8 which, like the anode screen 5, is made of nickel. The screen 8 carries a projection 9 which extends up to a distance of 0.5 mm. from the anode screen 5. The distance between the auxiliary anode 7 and the projection 6 of the cathode is 0.2 mm. The relative arrangement of the anode and the projection of the cathode can be clearly seen from FIG. 3. The relative arrangement of the cathode-screen projection 9 and the anode screen can be seen from FIGURE 4. The filling of the tube consists of neon of mm. of mercury column. To prevent delays in the ignition of the guard discharge between the projection 9 and the anode screen 5, one wing of the screen 8 has provided on it a small amount of fine pulverulent titanium 10 having absorbed in it the radio-active material tritium to an amount of about l C. A nickel pole 11 serves as an anode for atomising the peak 6 and the auxiliary anode 7 by sputtering in a glow discharge.

In FIGURE 5, the tube is indicated by 12, the cathode by 13, the anode by 14, the anode screen by 15, the cathode screen by 1-8, the projection of the cathode by 16 and the auxiliary anode by 17. The cathode screen 18 'is connected through a resistor 19 of 10 megohrns to the cathode lead and the anode screen 15 is connected through a resistor 20 likewise of 10 megohrns to the anode lead. The tube is fed from an alternating-voltage source 21 of 220 volts.

Branched from the'anode lead, through a sensitive element 22, is the connection to the igniting anode 17, which includes a resistor 23 which is also connected to the cathode through a capacitor 24. The sensitive element 22 comprises a photo-resistor of cadmium sulphide. The photo-resistor has a very high resistance if not radiated by light and a lowresistance upon radiation. Itv

light falls on the resistor 22, the voltage set up at the igniting anode 17 during the positive phase is such that the auxiliary discharge and hence the main discharge in trol by the auxiliary anode at an alternating voltage of volts from the source 21, whilst ignition still does not occur at 275 volts without control voltage at the igniting anode 17 r What is claimed is:

1. A glow discharge device comprising a glow discharge tube including an envelope containing an ionizable gaseous medium, a cold, non-activated cathode, an anode, and an igniting anode all within said envelope, said anode and cathode electrodes defining a main discharge path therebetween and said igniting anode and said cathode defining an auxiliary discharge path therebetween, a tubular screen electrode substantially surrounding said anode and interposed between the cathode and igniting anode, and a second screen electrode positioned on the side of said tubular screen electrode remote from the anode, means including a resistor connecting said second screen electrode to said cathode, means including a resistor connecting said tubular screen electrode to said anode, and means to apply a cyclic alternating potential between the cathode and anode, at least one of said screen electrodes having'a projection directed towards the other screen electrode whereby with the alternating potential applied between the cathode and anode a relatively weak discharge occurs between the two screen electrodes at a distance from the main discharge path at which delays in ignition in the auxiliary discharge path are prevented without a decrease in igniting potential in the main discharge path. 4

2. A glow discharge device comprising a glow-discharge tube including an envelope containing an ionizable gaseous medium, a cold, non-activated cathode, an

charge tube including an envelope containing an ionizable gaseous medium, a cold, non-activated cathode, an anode, and an igniting anode all within said envelope, said anode and cathode electrodes defining a main discharge path therebetween and said igniting anode and said cathode defining an auxiliary discharge path therebetween, a tubular screen electrode substantially surrounding said anode and interposed between the cathode and igniting anode, and a second screen electrode positioned on the side of said tubular screen electrode remote from the anode and spaced from the main discharge path, means including a resistor connecting said second screen electrode to said cathode, means including a resistor connecting said tubular screen electrode to said anode, and means to apply a cyclic alternating potential between the cathode and anode, at least one of said screen electrodes having a projection directed towards the other screen electrode whereby with the alternating potential applied between the cathode and anode a relatively weak discharge occurs between the two screen electrodes at a distance from the main discharge path at which delays in ignition in the auxiliary discharge path are prevented without a decrease in igniting potential in the main discharge path.

anode, and an igniting anode all within said envelope, i

said anode and cathode electrodes defining a main discharge path therebetween and said igniting anode and said cathode defining an auxiliary discharge path therebetween, a cylindrical screen electrode surrounding said anode and interposed between the cathode and igniting anode, and a second screen electrode positioned on the side of said cylindrical screen electrode remote from the anode and being shielded therefrom by said cylindrical screen electrode, means including a resistor connecting said second screen electrode to said cathode, means including a resistor connecting said cylindrical screen electrode to said anode, and means to apply a cyclic alternating potential between the cathode and anode, at least one of said screen electrodes having a projection directed towards the other screen electrode whereby with the alternating potential applied between the cathode and anode a relatively weak discharge occurs between the two screen electrodes at a distance from the main discharge path at which delays in ignition in the auxiliary discharge path are prevented without a decrease in igniting potential in the main discharge path.

3. A glow discharge device comprising a glow dis- 4. A glow discharge tube comprising an envelope containing an ionizable gaseous medium, a cold, non-activated cathode, an anode, and an igniting anode all within said envelope, said anode and cathode electrodes defining a main discharge path therebetween and said igniting anode'and said cathode defining an auxiliary discharge path therebetween, a tublular screen electrode substantially surrounding said anode and interposed between the cathode and igniting anode, a second screen electrode positioned on the side of said tubular screen electrode remote from the anode and spaced from the main discharge path, at least one of said screen electrodes having a projection directed towards the other screen electrode whereby with an alternating potential -i applied between the cathode and anode a relatively weak discharge occurs between the two screen electrodes at a distance from the main discharge path at which delays in ignition in the auxiliary discharge path are prevented without a decrease in igniting potential in the main dis- 1 charge path.

References Cited in the file of this patent UNITED STATES PATENTS 2,444,072 Stutsman June 29, 1948 2,607,021 Von Gugelberg Aug. 12, 1952, 2,736,840 Tosswell Feb. 28, 1956

Claims (1)

1. A GLOW DISCHARGE DEVICE COMPRISING A GLOW DISCHARGE TUBE INCLUDING AN ENVELOPE CONTAINING AN IONIZABLE GASEOUS MEDIUM, A COLD, NON-ACTIVATED CATHODE, AN ANODE, AND AN IGNITING ANODE ALL WITHIN SAID ENVELOPE, SAID ANODE AND CATHODE ELECTRODES DEFINING A MAIN DISCHARGE PATH THEREBETWEEN AND SAID IGNITING ANODE AND SAID CATHODE DEFINING AN AUXILIARY DISCHARGE PATH THEREBETWEEN, A TUBULAR SCREEN ELECTRODE SUBSTANTIALLY SURROUNDING SAID ANODE AND INTERPOSED BETWEEN THE CATHODE AND IGNITING ANODE, AND A SECOND SCREEN ELECTRODE POSITIONED ON THE SIDE OF SAID TUBULAR SCREEN ELECTRODE REMOTE FROM THE ANODE, MEANS INCLUDING A RESISTOR CONNECTING SAID SECOND SCREEN ELECTRODE TO SAID CATHODE, MEANS INCLUDING A RESISTOR CONNECTING SAID TUBULAR SCREEN ELECTRODE TO SAID ANODE, AND MEANS TO APPLY A CYCLIC ALTERNATING POTENTIAL BETWEEN THE CATHODE AND ANODE, AT LEAST ONE OF SAID SCREEN ELECTRODES HAVING A PROJECTION DIRECTED TOWARDS THE OTHER SCREEN ELECTRODE WHEREBY WITH THE ALTERNATING POTENTIAL APPLIED BETWEEN THE CATHODE AND ANODE A RELATIVELY WEAK DISCHARGE OCCURES BETWEEN THE TWO SCREEN ELECTRODES AT A DISTANCE FROM THE MAIN DISCHARGE PATH AT WHICH DELAYS IN IGNITION IN THE AUXILIARY DISCHARGE PATH ARE PREVENTED WITHOUT A DECREASE IN IGNITING POTENTIAL IN THE MAIN DISCHARGE PATH.

Images