Alpha-numeric Display Tubes

Abstract

A display tube has a plurality of cathodes extending into an atmosphere of rare gas within a transparent envelope to form a visible matrix of cathode glow electrodes. Each cathode is surrounded by an anode plate with shaped apertures putting a compartment about each separate cathode. Electronic coding, decoding and buffering circuits are connected to form individually recognizable patterns from excitation of selected cathodes.

Description

This invention has reference to tubes for displaying alpha-numeric information and to calculating machines embodying such display tubes.

Tubes for displaying alpha-numeric information have been in use for displaying information, for example to provide the display means for indicating the numbers stored in the respective stages of a register of a calculating machine. Generally these have included a plurality of cathodes arranged in a stack and each cathode has been shaped in the form of a numeral so that the stack represents the numerals 0 to 9. These cathodes are located within a casing which is formed on one side with a lattice work and which casing constitutes an anode. The anode and cathodes are contained in a transparent envelope in an atmosphere of rare gas, for example neon with small quantities of argon and mercury. When a striking voltage is applied between the anode and a selected one of the cathodes the area around the cathode is caused to glow and this glow assumes the shape of the selected cathode.

Such tubes are connected in a calculating machine to display to an operator the number stored in a register of the calculating machine. Such a display is described for example in the specification of our British Pat. No. 925308. In such an arrangement separate connections are made from each stage of a register to a tube and such connections are costly.

It has also been proposed to provide a number indicating means in the form of a matrix of grid having a plurality of lamps and these lamps were selectively lit whereby a number was displayed. Such a display is described in the specification of our U.S. Pat. No. 684055. It has also been proposed to include matrix displays in a calculating machine.

It is an object of the present invention to provide an improved display particularly for use with a calculating machine.

According to one aspect of the present invention an alpha-numeric character display tube comprises a housing having a base of electrically insulating material and sealed envelope with a transparent viewing face a plurality of cathode wires extending through the base whereby the one ends of the wires form or are connected to a cathode matrix and an anode spaced from the cathode matrix within the housing which anode is connected to one end of a connecting wire the other end of the anode and cathode matrix wires each extending outside the housing for connection to a decoding circuit and arranged so that when a striking potential is applied between the anode and selected ones of the plurality of cathodes which selected ones of the cathodes together represent a character, the representation of the character is displayed in the tube.

Also according to the present invention a display means for a calculating machine comprises a register having at least one stage into which a digit is stored, a decode circuit, and an alpha-numeric character display tube associated with a respective stage of the register wherein the display tube comprises a housing having a base of electric insulation material and a cover, with a transparent face a plurality of cathode wires extending through the base whereby the one ends of the wires form a cathode matrix, and an anode spaced from the cathode formation within the housing which anode is connected to one end of a connecting wire the other ends of the anode and cathode matrix wires extending outside the housing for connection to the decode circuit whereby when a striking potential is applied between the anode and selected ones of the plurality of cathodes which together represent a character. The representation of the character is displayed in the tube, corresponding to the number stored in the respective stage of the register.

A character display in accordance with the invention will now be described by way of example with reference to the accompanying drawings wherein:

FIG. 1 is a circuit diagram

FIG. 2 is an exploded perspective view of a display tube and

FIG. 3 is a diagrammatic representation of a cathode display matrix.

Referring to FIG. 1 there is shown a register 1 having a plurality of stages 1a, 1b . . . 1j. A connection is made between the stages of the register 1 and a buffer circuit 2 and a further connection made from the buffer circuit 2 to a decode circuit 3 through connection lines 4.

The register 1 comprises a dynamic register in which the numbers stored in the respective stages of the register are circulated around the register and the buffer circuit 2. If it is required to enter a digit into a stage of the register or transfer or read a digit in the stage of the register this is effected as the predetermined stage is passing through the buffer circuit 2. The number is read from the buffer circuit by passing a train of ten pulses into the buffer. This causes the digit stored in that stage of the register to return to its initial condition. It is also so arranged that a control pulse is emitted from the stage of the register when that pulse passes through zero. This control pulse is passed from the buffer circuit 2 to the decode circuit 3 so that an indication can be given of the condition of the buffer circuit in dependence upon the time at which this control pulse is issued by an appropriate stage of the register 1. Depending upon which number is stored in the register so a selected one of the lines 4 connected between the buffer circuit and the decode circuit is operative.

The train of decade pulses from the supply are also passed to a timer circuit 16 divided into stages. Each stage of the circuit 16 receives 10 pulses and subsequent pulses are passed to the next or subsequent stages. Each stage has an output which is connected to a respective connection 14 so that a positive potential or envelope pulse is applied to each connection for a duration of 10 pulses of the train from the supply.

The output from the decode circuit 3 comprises 35 separate lines 5 with a separate resistance 6 connected in each line which is connected to a plurality of alpha-numeric display devices 7 connected in parallel. Each line 5 is connected to a respective wire 8 of the display device 7 which wire is mounted in a preform 9 (FIG. 2) of a sintered glass preferably borosi/icate which is held in a metal framework 10 in the display device 7. This metal framework is kovar. A series of apertures 11 is formed in the glass preform 9 in lines. Preferably these apertures are arranged in five vertical straight lines and seven horizontal lines. The ends of the wires 8 which are made of Kovar an alloy of nickel, iron and cobalt protrude through and are sealed in the apertures 11 in the glass preform. These wires 8 constitute cathodes selected ones of which together serve as a representation of a character.

An additional aperture 11a is formed in the preform 9 and an additional wire 8a protrudes through the preform and this additional wire constitutes a representation of a decimal point.

A cathode spacing plate 20, having a series of apertures 21 which are of a size of about 1.25 mm diameter and spaced in corresponding relationship with the respective wires 8 extending through the preform 9 fits over the preform 9. The wires 8 extend into but not through the apertures 21 in the spacing plate in order that if the material of the wires should melt or become distorted the wires will not become shorted one with another.

An anode mesh 22 consisting of a meshwork of thin metal wires is spaced from the spacing plate 20 and the anode mesh is covered by a flat envelope viewing face or window 23 of transparent material.

An anode spacing plate 24 is spaced between the cathode spacing plate 20. This anode spacing plate has a plurality of square or rectangular apertures 24a corresponding in number and position (but not shape) to the apertures 21 in the cathode spacing plate 20.

A pair of supporting wires 26 are secured in the preform 9 and these wires are located in complementary holes 27 in the spacing plates 20, 24 and in the anode mesh 22.

The metal framework 10 has a connecting exhaust pipe 28.

When the envelope is to be assembled the preform 9 is located in abutment with the metal framework 10 which are sealed together by an Eddy Current Heater or an R.F. Heater. The materials of the preform 9 and the framework 10 have substantially the same coefficient of linear expansion. Subsequently the spacing plates 20 and 24 and anode mesh 22 are fitted into the framework 10 over the preform 9 and the flat window 23 is fitted in abutting relationship over the other end of the framework the window 23 is likewise welded to the framework 10 to seal the envelope. Subsequently the envelope is filled with an insert rare gas for example neon with a small quantity of argon and a small quantity of mercury. The gas is then partially evacuated from the envelope so that the pressure within the envelope is low, preferably about 125 to 225 millimeters of mercury.

When a voltage is applied between the anode and selected cathodes there is a clow of current between the anode and cathodes which causes a glow in the atmosphere adjacent the selected cathodes. This glow is defined more closely by the apertured anode plate 24 to give a more definite image.

It is arranged that there are a corresponding number of display devices to the number of stages 1a, 1b . . . 1j of the register 1 and the anode 13 of a respective display device 7 as shown in FIG. 1 is connected to the corresponding stages of the timer circuit 16.

Likewise, the 35 cathodes in the number tubes are connected to the respective 35 lines constituting the output from the decode circuit 3.

The wire 8a representing the decimal part is connected to the decimal point part of the circuit.

The decode circuit 3 consists of a diode matrix with connections made between each respective input from the buffer which is arranged to energize one of the lines 5 to appropriate connections to the cathodes 8. The connections to the cathodes 8 are selected in dependence upon which cathodes are required to strike to display a selected number.

Thus for example if the number 8 is required to be displayed the second, third, fifth and sixth cathodes of the first column, the first, fourth and seventh cathodes of the second third and fourth columns and the second, third, fifth and sixth cathodes of the fifth column are energized. This is shown in FIG. 3. In order that other numbers or letters may be displayed, selected other various cathodes are energized.

When it is required to display a number indicated in the respective stages 1a, 1b . . . 1j of the register 1 these stages are addressed in turn by passing a train of decade pulses into that stage at the same time as an envelope pulse is applied to the anode of the respective tube on which the number is to be displayed. Thus for example if the number 8 is entered in the first stage of the register 1a a series of 10 pulses are applied to the stage 1a of the register and a positive voltage envelope pulse is applied to the anode of the first display tube. As the first stage of the register passes through zero a control pulse is emitted which is passed to the buffer 2 to energize one of the lines 4 to the decode circuit 3. In this case the second line is energized (because the buffer circuit will be energized when the stage of the register passes from 9 to zero that is on the passage of the second pulse into the register). Energization of the second line 4 will cause the decode circuit to be energized and cause a negative voltage to be applied the selected lines to the cathode whereby the cathodes as shown in FIG. 3 are energized. Thereby the number 8 is displayed in the first display device.

In a like manner the number displayed in the second stage of the register is displayed in the second number tube etc. with the number displayed in the stage 1j of the register displayed in the last display device of the series.

Connections are made from the decode circuit 3 to the respective lamps but it may be suitable to have a common positive or common negative lead to the lamps.

In a modified form of the invention the display device preform has a plurality of semi conductor light emitting diode areas to which the cathode wires are connected. This is covered by the anode spacing plate 24 and anode mesh 22 so that when a potential is applied between the anode and cathode the semi conductor areas glow. Precerably these light emitting areas are areas of gallium arsenide formed on the preform 9.

Claims

1. An alpha-numeric character display tube comprising a housing having a base of electrically insulating material and sealed envelope with a transparent viewing face, a plurality of cathode wires electrically insulated from each other each extending through the base whereby the one ends of the wires form a cathode matrix and a transparent anode mesh spaced from the cathode matrix within the housing between the viewing face and the cathode wires which anode is connected to one end of a connecting wire, the other end of the anode and cathode matrix wires each extending outside the housing to a decoding circuit and means arranged to apply a striking potential between the anode and selected ones of the plurality of cathodes which selected ones of the cathodes together represent a character, the representation of the character being visually displayed in

2. An alpha-numeric character display tube according to claim 1 wherein the

3. An alpha-numeric character display tube according to claim 2 wherein a connection is made through the sintered base from outside the envelope.

4. An alpha-numeric character display like according to the preceding claim 1 wherein the anode comprises an anode mesh and an apertured anode spacing plate, the apertures of the anode corresponding to and being aligned with

5. An alpha-numeric character display tube according to the preceding claim 1 wherein the housing contains a rare gas comprising neon with a small

6. A display means for a calculating machine comprising a register having at least one stage into which a digit is stored, a decode circuit, an alpha-numeric character display tube associated with said stage of the register wherein the display tube comprises a housing having a base of electric insulation material and a cover with a transparent face, a plurality of separate electrically isolated cathode wires extending through the base whereby the one ends of the wires form a cathode matrix, a transparent anode spaced from the cathode formation within the housing and means connecting said anode and the other ends of the cathode matrix wires extending outside the housing to the decode circuit to apply a striking potential between the anode and selected ones of the plurality of cathodes which together represent a character in said matrix the representation of the character is displayed in the tube, corresponding to

7. A display means for a calculating machine according to claim 6 wherein the register comprises a dynamic register.