US2122269A - Tuning indicator tube - Google Patents

Description

June 28, 1938.

H. M. WAGNER 2,122,269

TUNING INDICATOR TUBE Filed Sept. 29, 1937 INVEN TOR. 1 HERBERT M. WAGNER ATTORNEY.

Patented June 28, 1938 UNITED STATES PATENT OFFICE TUNING INDICATOR TUBE Delaware Application September 29, 1937, Serial No. 166,252

6Claims.

My invention relates to electron discharge devices, more particularly to such devices useful as visual indicators of voltage and having a fluorescent electrode which is rendered luminous and has the appearance of a pattern of light, which changes in response to the change in the magnitude of the applied voltage, a device of this char acter being particularly useful as a tuning indicator in radio receiving sets. The present invention is a modification of the device of the character described and claimed in my Patent No. ,0 189 issued August 18, 1936.

It is an object of my invention to provide an electron discharge device of this general character which is particularly suitable for use as a tuning indicator in a radio receiving set in which resonance is indicated by a brilliant luminous glow in the form of a ring on the anode, and in which departure from resonance may be indicated by a decrease or an increase in the width of the luminous ring pattern.

One embodiment of such a. device useful as a tuning indicator and described in the patent above referred to comprises an envelope having within it a straight thermionic equipotential cathode provided with two separate emitting sections, one of which is surrounded by amplifier elements which may comprise a control grid and anode, and the other of which is surrounded by the tuning indicator elements of the tube consisting of a straight control electrode parallel to the cathode and a dish-shaped anode coated on its inner surface with fluorescent material, the dish-shaped anode being concentric with and surrounding the cathode and the control electrode. In operation electrons flow from the cathode to the fluorescent anode with sufficient velocity to bombard the fluorescent anode and render it luminous. The control electrodeis connected to the amplifier anode and the tube so connected into a receiving circuit that when the circuit is tuned to resonance with an incoming signal the luminous portion of the plate is of a predetermined width, preferably the device is so connected that the luminous portion of the anode of the tuning indicator portion is of. maximum width, the dark portion of minimum width, when the circuit is tuned to resonance, and preferably the entire anode is made fluorescent and-th dark portion disappears. According to the present invention, the indicator section of the tube is so designed that it forms a luminous annulus or ring of light, the width of which varies with voltage variations. The tuning indicator-elements could of course be incorporated as a unit in an envelope separate from the control grid and anode.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 shows an electron discharge device embodying my invention with parts broken away to show details of construction; Figures 2 and 3 are top views showing the tuning indicator portion of the tube and the pattern of light under different voltage conditions; Figure 4 is a perspective view of a modification of the electrode construction of the tuning indicator section of a tube made in accordance with my invention; Figure 5 is a section of another modification of the tuning indicator portion of the device shown in Figure l; and Figure 6 is a circuit diagram embodying a tuning indicator tube made in accordance with my invention.

The electron discharge device or tuning indicator tube shown in Figure 1 comprises an evacuated envelope l provided with the usual stem and press II and base I2. Supported from the press are a cathode l3, preferably the conventional indirectly heated equipotential type, and a grid I 4 concentric and preferably coextensive with and surrounding the cathode, and an anode I surrounding the grid. While shown as a trlode this portion of the tuning indicator tube could be of any other multi-element type.

In accordance with my invention the tuning indicator elements of the tube are placed at the upper end of the mount. The cathode I3 is extended upwardly and provided with a second emitting section [6 adjacent which is placed the control electrode H which may be a collar or ring surrounding the cathode near the lower end of the emitting section It. This control electrode I! is supported from and connected to one of the side rods i8 of the anode i 5. Surrounding and concentric with the emitting portion l8 of the cathode is an anode or target which may be cupshaped and having only on its bottom 20 a coating 2| fluorescent under electron bombardment. The electrons emitted from the cathode and striking the anode with suflicient velocity cause it to fluoresce. The collar portion 22 of the anode it prevents electrons from reaching the glass walls of the envelope.

In this type of tuning indicator the electrons travel radially outward from the cathode to the fluorescent coating on the anode in a wide beam.

The extent of the fluorescent surface of the anode reached by the electron beam is determined by the voltage on the control electrode ii. The less negative this electrode is with respect to the anode i9, that is the more positive with respect to the cathode IS, the greater the area of the anode covered by the beam and the greater the area of the fluorescent portion of the anode. According to my invention, the control electrode i1 is at a positive potential with respect to the cathode. The advantages of this are that the boundaries of the electron beam are sharp and well defined, there can be a high concentration of electrons at the edges of the luminous areas of the anode so that the edges are brighter and stand out more prominently, a. high current to the luminescent anode and hence high luminosity is obtained with low anode voltages, and the control electrode can be coupled directly to an amplifier. I have found also that a tube made in accordance with my invention is not critical to variations in cathode temperature, and that it can also be used with either alternating or direct voltages and currents.

The tube is viewed from the end so that the pattern of light is viewed as shown in Figures 2 and 3. As shown in Figure 2 and the dotted lines in the left hand side of Figure 1 when the control electrode is at a potential near that of the cathode most of the electrons go to the uncoated walls 22 and the anode fluoresces only over the small area shown as a thin ring indicated by the shaded lines in Figure 2. As the control electrode ll becomes more positive the electron stream is pulled down as shown on the right hand side of Figure 1 and more of the surfaces of the anode fluoresces until at a predetermined voltage the entire suriace of the bottom 20 of the anode l9 fluoresces. This is the pattern which is shown in Figure 3 as a wide ring and which is obtained when the circuit in which the tube is used is tuned to resonance. The range of indication can be made all the way from maximum dark space with no ring of light to a maximum bright area comprising a wide ring of light. i

In the modification shown in Figure 4 the anode lea is a cup-shaped member having sloping sides coated on the interior with a fluores cent coating 2la, the upper edge being provided with a vertical wall or lip 22a which is not coated. At the lower end of the coated portion of the cathode i6 and closely spaced from the bottom 20a of the cup-shaped member i9a is the ring-like control electrode Ila. When the ring-like member Fla is made sufllciently negative with respect to the fluorescent anode none of the electrons from the cathode reach the fluorescent coating but substantially all go to the lip 22a. As the control electrode Fla is made more positive the electrons are pulled down toward the control electrode so that a fluorescent ring appears on the coated portion of the anode iBa it being of greatest width when resonance is attained. Resonance could also be indicated by having the entire fluorescent coating lighted at all times except when resonance is attained in which case the negative control electrode would be made increasingly negative as resonance is approached so that none of the electrons are permitted to reach the fluorescent coating.

In Figure is shown a further modification of my invention. In this case the cathode iSa is provided with a rounded end extending just above the bottom of the cup-shaped anode 20. The control electrode I! is similar to that shown in Figure 1. The anode I! however is closed at the top by means of a wire mesh screen 23 which may be welded to the wall or lip 22 of the cupshaped member or insulatingly supported by the anode and connected to some other electrode, for example, the cathode for obtaining diflerent control characteristics. The modification shown in Figure 5 operates in the same manner as that shown in Figures 1 and 2.

In Figure 6 I show a circuit embodying a tube ,made in accordance with my invention. The

anode l5 of the triode section and the anode iii of the tuning indicator section are electrically connected to each other through a resistor 25. The fluorescent anode is connected directly to a source of voltage supply 26. When no current flows from cathode i3 there is no voltage drop in resistor 25 and the anode i5 and control electrode II, which is connected to it, are at substantially the same potential as the anode iii of the tuning indicator section of the tube. Under these conditions the pattern of light forms a wide ring as shown in Figure 3, and the anode fluoresces around its entire bottom surface. When a current flows in the circuit of the anode ii a potential drop develops across the resistor 25 so that the anode i5 and control electrode II are made more negative with respect to the anode or target of the tuning indicator section of the tube 20, and the control electrode approaches the potential of the cathode, producing a thin ring pattern of light such as indicated in Figure 2, or no light at all. The magnitude of the current through the triode portion of the tube is determined by the bias on the control grid M.

In the circuit shown, a diode detector or rectifier 21 has its anode 28 and its cathode 29 connected to opposite sides of the secondary of the intermediate or radio frequency transformer 32 tuned by condenser 36, the cathode being connected through the resistor 30 and by-pass condenser SL The cathode side of the transformer 32 is connected to the control grid l4 through resistor 33, the grid being by-passed by means o1 by-pass condenser 34 so that a bias is impressed on the grid H. The conductor 35 may be connected to the automatic volume control circuit. In the arrangement shown with the set unturned and no signal passing through the transformer 32, no current passes through resistor 30 and no bias is developed. The grid i4 is at ground potential and permits current to flow through the triode section of the tube under which conditions the control electrode i1 is at a potential near that of the cathode as described above, the light pattern takes the form shown in Figure 2. With the set tuned to a signal a rectified current passes through resistor 30 developing a drop across this resistor and impressing a bias on the control grid i l of the triode through the resistor 33. This reduces the current passing through the triode in proportion to the bias impressed upon the grid so that the control electrode i'i becomes more positive with respect to the cathode II. The constants of the various elements are so chosen that when tuned to resonance the pattern of light is of the greatest width and forms the pattern shown in Figure 3.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it

will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having an envelope, a cathode within said envelope for emitting electrons, a 'cup shaped anode surrounding said cathode and havingits interior surface coated with a fluorescent material for receiving electrons from said cathode to produce a luminous annular shaped pattern on said anode, a control electrode comprising a ring positioned between said anode and said cathode and surrounding the cathode for determining the area of the fluorescent surface of the anode reached by the electrons from said cathode.

2. An electron discharge device having an en velope, a cathode within said envelope for emitting electrons, a cup-shaped anode surrounding said cathode and having its interior surface coated with a fluorescent material for receiving electrons from said cathode to produce a ringlike pattern of light, a ring-like control electrode between said cathode and said anode and surrounding the cathode, said ring-like control electrode being positioned adjacent the bottom of said cup-shaped member to control the electrons from said cathode to the coated surface of said anode to vary the width of the ring-like pattern of light on the coated surface of the anode.

3. An electron discharge device having an envelope, a cathode within said envelope and having a coated portion for emitting electrons, a cupshaped anode surrounding the emitting portion of said cathode and having its interior surface coated with a fluorescent material for receiving electrons from said cathode to produce a luminous annular-shaped pattern on the anode. a

ring-like control electrode between said .cathode and anode and surrounding the cathode, said ring-like control electrode being positioned near one end of the emitting portion of the cathode and adjacent the bottom of said cup-shaped member to control the electrons from said cathode to the coated surface of said anode to vary the width of the annular-shaped pattern light on the coated surface of the anode.

4. An electron discharge device having an envelope, a cathode within said envelope for emitting electrons, a cup-shaped member having a flat bottom surrounding said cathode and having the interior surface of the bottom coated with a fluorescent material for receiving electrons from said cathode to produce a luminous annularshaped pattern on the bottom of said anode, a ring-shaped control electrode positioned around said cathode adjacent the bottom of said anode for determining the area of the surface of the anode reached by the electrons from said cathode.

5. An electron discharge device having an envelope, a straight thermionic cathode within said envelope for emitting electrons, a cup-shaped anode having sloping sides surrounding said cathode and having the interior surface of the sloping sides coated with fluorescent material for receiving electrons from said cathode to produce a ringlike pattern of light, a flat ring-like control electmde between said cathode and anode and surrounding said cathode, said ring-like control electrode being positioned adjacent the bottom of said cup-shaped member to control the electrons from said cathode to the coated surface of the sloping sides of said anode to vary the width of the ring-like pattern of light on the coated surface of the anode.

6. An electron discharge device having an envelope, a cathode within said envelope and having its end coated with electron emitting material, a cup-shaped anode having straight sides and a flat bottom surrounding said cathode, the inner surface of the bottom of the anode being coated with a fluorescent material Ior receiving electrons from said cathode to produce a luminous annular shaped pattern of light on said anode, a ring-like control electrode surrounding said cathode and positioned between said anode and said cathode adjacent the bottom of said anode for determining the area of the fluorescent surface of the anode reached by the electrons from the oathode, and a mesh like screen covering said cupshaped anode and secured to the top 01 said cupshaped anode.

T M. WAGNER.

DISCLAIMER 2,122,269.Herbert M. Wagner, Newark, N. J. Toma Imncuroa Tmm. Patent dated June 28, 1938. Disclaimer filed August 13, 1940, by the assignee,

Radio Corporation of America.

H 13' enters this disclaimer of claims 1, 2, 3, and 5 of said Letters Patent.

[ final Gazette September 8, 1940.]

will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having an envelope, a cathode within said envelope for emitting electrons, a 'cup shaped anode surrounding said cathode and havingits interior surface coated with a fluorescent material for receiving electrons from said cathode to produce a luminous annular shaped pattern on said anode, a control electrode comprising a ring positioned between said anode and said cathode and surrounding the cathode for determining the area of the fluorescent surface of the anode reached by the electrons from said cathode.

2. An electron discharge device having an en velope, a cathode within said envelope for emitting electrons, a cup-shaped anode surrounding said cathode and having its interior surface coated with a fluorescent material for receiving electrons from said cathode to produce a ringlike pattern of light, a ring-like control electrode between said cathode and said anode and surrounding the cathode, said ring-like control electrode being positioned adjacent the bottom of said cup-shaped member to control the electrons from said cathode to the coated surface of said anode to vary the width of the ring-like pattern of light on the coated surface of the anode.

3. An electron discharge device having an envelope, a cathode within said envelope and having a coated portion for emitting electrons, a cupshaped anode surrounding the emitting portion of said cathode and having its interior surface coated with a fluorescent material for receiving electrons from said cathode to produce a luminous annular-shaped pattern on the anode. a

ring-like control electrode between said .cathode and anode and surrounding the cathode, said ring-like control electrode being positioned near one end of the emitting portion of the cathode and adjacent the bottom of said cup-shaped member to control the electrons from said cathode to the coated surface of said anode to vary the width of the annular-shaped pattern light on the coated surface of the anode.

4. An electron discharge device having an envelope, a cathode within said envelope for emitting electrons, a cup-shaped member having a flat bottom surrounding said cathode and having the interior surface of the bottom coated with a fluorescent material for receiving electrons from said cathode to produce a luminous annularshaped pattern on the bottom of said anode, a ring-shaped control electrode positioned around said cathode adjacent the bottom of said anode for determining the area of the surface of the anode reached by the electrons from said cathode.

5. An electron discharge device having an envelope, a straight thermionic cathode within said envelope for emitting electrons, a cup-shaped anode having sloping sides surrounding said cathode and having the interior surface of the sloping sides coated with fluorescent material for receiving electrons from said cathode to produce a ringlike pattern of light, a flat ring-like control electmde between said cathode and anode and surrounding said cathode, said ring-like control electrode being positioned adjacent the bottom of said cup-shaped member to control the electrons from said cathode to the coated surface of the sloping sides of said anode to vary the width of the ring-like pattern of light on the coated surface of the anode.

6. An electron discharge device having an envelope, a cathode within said envelope and having its end coated with electron emitting material, a cup-shaped anode having straight sides and a flat bottom surrounding said cathode, the inner surface of the bottom of the anode being coated with a fluorescent material Ior receiving electrons from said cathode to produce a luminous annular shaped pattern of light on said anode, a ring-like control electrode surrounding said cathode and positioned between said anode and said cathode adjacent the bottom of said anode for determining the area of the fluorescent surface of the anode reached by the electrons from the oathode, and a mesh like screen covering said cupshaped anode and secured to the top 01 said cupshaped anode.

T M. WAGNER.

DISCLAIMER 2,122,269.Herbert M. Wagner, Newark, N. J. Toma Imncuroa Tmm. Patent dated June 28, 1938. Disclaimer filed August 13, 1940, by the assignee,

Radio Corporation of America.

H 13' enters this disclaimer of claims 1, 2, 3, and 5 of said Letters Patent.

[ final Gazette September 8, 1940.]

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