US3641533A

US3641533A - Solid-state electroluminescent moving display device

Info

Publication number: US3641533A
Application number: US836704A
Authority: US
Inventors: Frederick B Sylvander
Original assignee: Bendix Corp
Current assignee: Bendix Corp
Priority date: 1969-06-26
Filing date: 1969-06-26
Publication date: 1972-02-08
Anticipated expiration: 1989-02-08
Also published as: JPS4929114B1; FR2064797A5; GB1276222A

Abstract

A device for providing a moving display having an electroluminescent phosphor layer arranged to emit a band of light when alternating current voltages of different amplitudes are applied across the phosphor layer. A layer having a plurality of electrodes separated by transparent resistive material is positioned at one side of the phosphor layer and a common electrode layer is positioned at the opposite side of the phosphor layer. The voltages are applied to the electrodes and to the common electrode layer and the amplitudes of the voltages are changed sequentially to cause the band of light to move in a direction and at a speed in accordance with the sequence and rate of change in the amplitudes of the voltages.

Description

waited States Patent Sylvander [151 3,641,533 [451 Feb. 8, 1972 [54] SOLID-STATE ELECTROLUMINESCENT MOVING DISPLAY DEVICE [72] Inventor: Frederick B. Sylvander, Rutherford, NJ.

[73] Assignee: The Bendix Corporation [22] Filed: June 26, 1969 [21] Appl. No.: 836,704

3,234,531 2/1966 Cleaver ..340/198 3,479,646 11/1969 Requa ..340/324 3,525,091 8/1970 Lally ...340/324 3,379,927 4/1968 Yando ..3l5/55 [57] ABSTRACT A device for providing a moving display having an electroluminescent phosphor layer arranged to emit a band of light when alternating current voltages of different amplitudes are applied across the phosphor layer. A layer having a plurality of electrodes separated by transparent resistive material is positioned at one side of the phosphor layer and a common electrode layer is positioned at the opposite side of the phosphor layer. The voltages are applied to the electrodes and to the common electrode layer and the amplitudes of the voltages are changed sequentially to cause the band of light to. move in a direction and at a speed in accordance with the sequence and rate of change in the amplitudes of the voltages.

5 Claims, 22 Drawing Figures CO/VDUCT/l E MATER/AL SOLID-STATE ELECTROLUMINESCENT MOVING DISPLAY DEVICE BACKGROUND OF THE INVENTION Field of the Invention CROSS-REFERENCE TO A RELATED U.S. PATENT The present invention is directed. to improvements in solidstate devices of a type providing illuminated moving displays such as that disclosed in a U.S. Pat. No. 3,543,083, granted Nov. 24, 1970 on a US. application Ser. No. 668,099 filed Sept. 15, 1967 by Frederick Blancke Sylvander, inventor of the present invention, and assigned to The Bendix Corporation, assignee of the present invention. In the form of the invention disclosed in the US. Pat. No. 3,543,083, there is provided a piezoelectric material in generating standing waves of vibrations to achieve the moving display. The piezoelectric material is difficult to machine while the generation of the standing waves required an excitation alternating current voltage having a frequency equal to the resonant frequency of the piezoelectric material. Temperature changes changed the resonant frequency of the piezoelectric material to the extent that the excitation voltage was unable to cause the piezoelectric material to generate the standing waves.

The present invention overcomes the disadvantages of difficult manufacturing and temperature sensitivity by eliminating the need for standing waves of vibration, and hence the piezoelectric material. The present invention is directed to an improvement in the display device of the type including a layer of electroluminescent phosphor, together with means for applying across the phosphor layer alternating voltages having a gradient along the phosphor layer to provide the symbol, as described and claimed broadly in the US. Pat. No. 3,543,083. However instead of a piezoelectric material being provided in the means for applying the alternating voltages across the layer of electroluminescent phosphor, as in the specific form of the invention disclosed in the US. Pat. No. 3,543,083, in the improvement of the present invention there are provided in the means for applying the alternating voltages across the layer of electroluminescent phosphor, a plurality of electrodes separated by resistive material so that alternating current voltages having different sequential changing amplitudes, related to the light emitting threshold level of electroluminescent phosphor, may be simultaneously applied across the electroluminescent phosphor to achieve a display symbol that moves in a direction and at a rate in accordance with the sequence and the rate of change of the amplitudes.

SUMMARY OF THE INVENTION A device for displaying a moving symbol comprising an electroluminescent phosphor. A layer having a plurality of electrodes separated by resistive material is positioned at one side of the phosphor layer and a common electrode layer is positioned at the opposite side of the phosphor layer. Alternating current voltages are applied to the electrodes and to the common electrode layer to provide the symbol. The amplitudes of the voltages are changed sequentially causing the symbol to move in a direction and at a speed in accordance with the sequence and rate of change of the alternating current voltages.

Oneobject of the present invention is to provide a solidstate electroluminescent moving display device operative over a wide temperature range.

Another object of the present invention is to provide a device that is easy to manufacture.

Another object of the present invention is to provide a solidstate device displaying a linear moving symbol.

Another object of the present invention'is to provide a solidstate device displaying a two-dimensional moving symbol.

Another object of the present invention is to provide a solidstate device display a circular moving symbol.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein three embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration purposes only and are not to be construed as defining the limits of the invention.

DESCRIPTION OF THE DRAWINGS FIG. I shows a novel solid-state electroluminescent device constructed in accordance with theinvention for displaying a one-dimensional moving symbol.

FIG. 2 shows a system using the display device shown in FIG. 1 for providing a moving display corresponding to the relative angular velocities of two devices, such as on an aircraft.

FIG. 3 shows three voltage outputs from the synchro differential transmitter in the display system shown in FIG. 2.

FIGS. 4A, 4B and 4C show a moving symbol in the fonn of a band of light in response to applied changing voltages in the display system shown in FIG. 2.

FIG. 5 shows another embodiment of the invention for providing a circular moving display.

FIG. 6 is a sectional view of the device shown in FIG. 5 along the line 6-6 as viewed in the direction of the arrows.

FIG. 7 shows the electrode and resistive material layer of the device shown in FIG. 5.

FIG. 8 shows a solid-state electroluminescent device similar to the device shown in FIG. 1 for displaying a two-dimensional moving symbol.

FIG. 9 shows a system using the display device of FIG. 8 for displaying a two-dimensional moving symbol corresponding to conditions, such as the pitch and yaw of an aircraft.

FIGS. 10A and 108 show six voltage outputs from the synchros in the display system shown in FIG. 9.

FIGS. llA through 111 show a moving two-dimensional symbol in accordance with the applied alternating current voltages in the display system of FIG. 9.

DESCRIPTION OF THE INVENTION Referring to FIG. 1, there is shown a novel solid-state electroluminescent device 1 for displaying a moving symbol and having a layer 3 of conductive material, such as aluminum, connected to a terminal 4 connected to ground. The layer 3 may be transparent although this is not essential. A layer 8 of an electroluminescent phosphor is affixed to layer 3 of conductive material. The electroluminescent phosphor may be zinc sulfide or cadmium sulfide activated by copper, gold or silver. The electroluminescent phosphor emits light when subjected to an alternating current voltage greater than the light emitting threshold level of the electroluminescent phosphor.

A layer

I4 having electrodes

15, 15A and 15B separated by transparent resistive material 18, such as stannous chloride, nichrome or gold, is affixed to layer 8 of electroluminescent phosphor for controlling the illuminating of the electroluminescent phosphor. The thickness of the transparent resistive material 18 determines its resistivity and transparency.

Terminals

20, 20A and 20B receive alternating current voltages and are connected to

electrodes

15, 15A and 15B, respectively. At least one of the alternating current voltage applied to

terminals

20, 20A and 2013, but not all of the applied alternating current voltages, should have an amplitude greater than the light-emitting threshold level of the electroluminescent phosphor. It is preferred that the amplitudes of alternating current voltages applied to

terminals

20, 20A and 208 be related to each other so that a band of light, emitted by the electroluminescent phosphor in response to the applied alternating current voltages, has a constant width. A layer 21 of transparent nonconductive material, such as glass, is affixed to electrode and resistive material layer 14 to protect layer 14 while permitting viewing of the electroluminescent phosphor and to support

layers

3, 8 and 14.

Layer 21 of a transparent material may be affixed to conductive layer 3 instead of to electrode and resistive material layer 14, as heretofore mentioned. When display device 1 is so constructed, it is immaterial whether the transparent material in layer 21 is conductive or nonconductive.

Voltage gradients exists between

electrodes

15, 15A and 158 when alternating current voltages, such as heretofore described, are applied to

terminals

20, 20A and 208 due to transparent resistive material 18. The portion of the electroluminescent phosphor of layer 8 subjected to a greater than threshold voltage has a larger area, due to a voltage gradient, than it would have if insulation separated

electrodes

15, 15A and 158. The increase in area of the electroluminescent phosphor of layer 8 emitting light causes device 1 to display a band of light having a larger width for ease of viewing.

Referring to FIG. 2, there is shown, for purpose of illustration, one use of display device 1 for providing a linear display corresponding to the difference in speed of rotation between two propellers on an aircraft. A propeller 23 is connected to a rotor winding 25 of an alternating current synchro transmitter 26 and drives rotor winding 25 at a rotational speed w, corresponding to the rotational speed of propeller 23. Rotor winding 25 of synchro 26 is energized by an alternating current voltage E,. Synchro 26 is a conventional type synchro transmitter and has common connected

stator windings

30, 31 and 32 providing output signals corresponding to the rotation of rotor winding 25.

Stator windings

30, 31 and 32 are connected to

stator windings

35, 36 and 37, respectively, of a conventional type differential synchro transmitter 40 having rotor windings 43, 44 and 45 commonly connected to ground. A second propeller 47 is connected to rotor windings 43, 44 and 45 of synchro 40 and drives rotor windings 43, 44 and 45 at a rotational speed corresponding to the rotational speed of propeller 47. Rotor windings 43, 44 and 45 of synchro 40 provide voltage E E and E as shown in FIG. 3, corresponding to the difference in speeds a), and m of

rotor windings

25 and 43, 44 and 45.

Rotor winding 43, 44 and 45 of differential synchro transmitter 40 are connected to terminals 20, A and 20B, respectively, of display device 1 having terminal 4 connected to ground and alternating current voltages E E and B are applied thereto. When the rotational speed of

propellers

23 and 47 are the same, device 1 displays a stationary band of light. When

propellers

23 and 47 rotate at different speeds, the band of light moves in a direction corresponding to the propeller which has the fastest rotational speed and the band of light moves at a speed corresponding to the difference in the rotational speeds of the

propellers

23 and 47, as hereinafter explained.

Referring to FIGS. 2, 3 and 4, for purposes of illustration, when the propellers of the aircraft are rotating at the same speed, rotational speed m of rotor winding of synchro transmitter 26 is equal to rotational speed (0 of rotor windings 43, 44 and 45 of differential transmitter 40 causing alternating current voltages E E and 13,, applied to display device 1, to remain constant in amplitude as if received from a synchro whose rotor winding is stationary. This results in display device 1 providing a centered band of light on the display as shown in FIG. 4A. The voltages E;,, E, and E have the following relationships:

E E, sin (m -m A difference in propeller speeds w, and m causes voltages E E and E to appear as voltages from a synchro having a rotating rotor winding. The changing amplitudes of voltages E E and E causes the band of light to move in a direction, as shown by the arrows in FIGS. 48 or 4C, determined by which propeller is rotating faster and at a rate in accordance with the difference in propeller speeds as hereinafter described. A small difference in propeller speeds results in the band of light moving slowly, while a large difference causes the band of light to move fast. With the relative motion of the propellers, the band of light moves in one direction ofl the scale at either the upper or lower end and returns at the lower or upper end, respectively, and provides a continuously moving display.

If two of the three applied alternating current voltages have amplitudes greater than the light emitting threshold of the electroluminescent phosphor, display device 1 will appear as an illuminated device with a dark band that appears to move in a direction determined by which propeller is rotating faster and at a speed in accordance with the difference in propeller speeds.

Referring to FIGS. 5, 6 and 7, there is shown a display device 50 cylindrical in shape for displaying circular movement and having a circular layer 51 of conductive material connected to a terminal 54. A circular layer 56 of electroluminescent phosphor, such as used in display device 1, is affixed to conductive material layer 51. A circular layer 58 having

electrodes

60, 60A and 60B, separated by transparent resistive material 61 as shown in FIG. 7, is affixed to the electroluminescent phosphor layer 56.

Electrodes

60, 60A and 60B are connected to terminals 65, 65A and 658 which receive alternating current voltages E E and E but not all voltages, has an amplitude greater than the light emitting threshold level of the electroluminescent phosphor. A circular layer 67 of transparent material, such as glass, is affixed to the electrode and resistive material layer 58 to protect layer 58, while permitting viewing of the electroluminescent phosphor, and to support

layers

51, 56 and 58.

Device 50 may be used in a system such as shown in FIG. 2 where voltages E E and E from synchro 40 are applied to terminals 65, 65A and 653, respectively, of device 50. A band of light emitted by electroluminescent phosphor in layer 56 of display device 50 moves in a circle in a direction determined by which

propeller

23 or 47 is rotating faster and at a speed in accordance with the difference between propeller speeds as heretofore explained for the operation of display device 1.

Referring to FIG. 8, there is shown a display device 70 which is another embodiment of the invention. Display device 70 is similar to display device 1 and has the same layers except that an electrode and resistive material layer 71, which is similar to electrode and resistance layer 14 of display device 1, has

additional electrodes

74, 74A and 74B, spacially related to

electrodes

15, 15A and 15B.

Terminals

75, 75A and 75B are connected to

electrodes

74, 74A and 743, respectively.

Electrode

74, 74A and 74B are shown in two parts which are electrically connected together and insulated from

electrodes

15, 15A and 158. The arrangement of

electrodes

15, 15A, 15B, 74, 74A and 748 provides a two dimensional symbol on display device 70 in response to alternating current voltages applied to

terminals

20, 20A, 20B, 75, 75A and 758 as hereinafter explained. At least one alternating current voltage applied to

terminals

20, 20A and 20B and one alternating current voltage applied to

terminals

75, 75A and 758 must have an amplitude greater than the lightemitting threshold of the electroluminescent phosphor of layer 8.

Referring to FIG. 9, 10A and 108, there is shown, for purposes of illustration, one use of display device 70 shown in FIG. 2, in which a system displays a symbol whose movement corresponds to the pitch and the yaw of an aircraft. A pitch sensor and a yaw sensor 82 provide signals E and E respectively, corresponding to the pitch and yaw of the aircraft.

Signals E and E are applied to conventional type amplifiers 84 and 85, respectively, which provides signals E and E, signals to

motors

88 and 89, respectively. The rotational speeds of the shafts of the

motors

88 and 89 correspond to signals E and

E Tachometers

90 and 91 are mechanically connected to the shafts of

motors

88 and 89, respectively, and provide feedback signals to amplifiers 84 and 85 for maintaining the rotational speed of

motors

88 and 89 in accordance with signals E and

E Motors

88 and 89 are used to rotate

rotor windings

92 and 93 of

synchros

95 and 96, respectively, at speeds corresponding to pitch signal E and yaw signal

E Rotor windings

92 and 93 of

synchros

95 and 96, respectively, are energized by an alternating current voltage E Synchros 95 and 96 have stator winding 102, 103 and 104 and 107, 108 and 109, respectively, commonly connected to ground.

Stator windings

102, 103 and 104 or synchro 95 provide voltages E E and E as shown in FIG. A, to terminals 20, A and 20B, respectively, of display device 70 in accordance with the angular position of rotor winding 92.

Stator windings

107, 108 and 109 of synchro 96 provide voltages E E and E as shown in FIG. 103, to

terminals

75, 75A and 75B of display device 70 in accordance with the angular position of rotor winding 93.

Referring to FIGS. 9 and 11A through 11G, when the aircraft is not moving about its pitch or yaw axis, display device 70 provides a stationary light symbol such as shown in FIG. 1 1A. When the aircraft moves about the pitch axis, the changing amplitudes of voltages E E and E causes the symbol to move in a direction, as shown by the arrows in FIGS. 118 or 11C, determined by the pitch direction and at a rate in accordance with the pitch angle. When the aircraft moves about the yaw axis, the changing amplitudes of voltages E E and E causes the symbolto move in a direction, as shown by the arrows in FIGS. 11D or 1 1E, determined by the yaw direction and at a rate in accordance with the yaw angle. When the aircraft moves about the pitch and yaw axes, the changing amplitudes of voltages E E E E E and E causes the symbol to move in a direction, as shown by the arrows in FIGS. 11F, 11G, 11H or III, determined by the pitch and yaw directions and at a rate in accordance with the pitch and-yaw angles. The shape of the symbol will change as it moves, however the change is unimportant as device 70 will appear to display a moving symbol. With movement of the aircraft about the pitch axis or the yaw axis, the symbol moves in one direction off the scale at one end and returns at an opposite end and provides a continuously moving symbol.

A solid state display device constructed according to the present invention is relatively easy to manufacture, is operative over a wide temperature range and provides a linear, a circular or a two-dimensional display.

While three embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes may also be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. In a device for displaying a moving symbol of a type including a first layer of an electroluminescent phosphor having a light emitting threshold voltage level, a second layer positioned at one side of the first phosphor layer, a third common electrode layer positioned at the opposite side of the first phosphor layer; wherein the improvement comprises the second layer including a first set of a plurality of electrodes separated by transparent resistive material selected from a group consisting of stannous chloride, nichrome and gold, means for applying alternating current voltages of different amplitudes related one to the other simultaneously to the plurality of electrodes of the first set of electrodes and to the third common electrode layer, the alternating current voltage applied to one of said plurality of electrodes of the first set of electrodes having an amplitude greater than the light emitting threshold voltage level of the electroluminescent phosphor of the first layer, and the alternating current voltage simultaneously applied to the other of said plurality of electrodes of the first set of electrodes being less than said threshold voltage level, the greater amplitude of the alternating current voltage applied to said one electrode causing the first phosphor layer to emit a band of light to provide a symbol on the first layer of electroluminescent phosphor, and means for changing the amplitudes of the voltages simultaneously applied to said plurality of electrodes of said first set so as to sequentially apply to each one of said plurality of electrodes of said first set an alternating current voltage having art amplitude greater than the light emitting threshold voltage level of the first phosphor layer to cause the emitted light band symbol to move on the first layer of electroluminescent phosphor in a direction and at a speed in accordance with the sequence and rate of change of the alternating current voltages.

2. The improvement defined by claim 1 in which the means for changing the amplitudes of the alternating current voltages across the first layer of electroluminescent phosphor includes a first signal device having a rotor winding energized by an alternating current voltage, the rotor of the first signal device being rotatable in accordance with a first condition, the first signal device having stator windings providing output voltages in accordance with the rotation of the rotor winding, another signal device having stator windings, the stator windings of said other signal device being connected back to back to the stator windings of the first signal device and energized by the output voltages from the stator windings of the first signal device, and rotor windings of the other signal device being commonly connected to the third common electrode layer, the rotor windings of the other signal device being rotatable in accordance with a second condition to provide output voltages in accordance with a difference in the rotation of the rotor winding of the first signal device and the rotation of the rotor windings of the second signal device, and each rotor winding of the second signal device being connected to a corresponding electrode of the plurality of electrodes of the first set of the second layer to change the voltages across the electroluminescent phosphor of the first layer in accordance with the output voltages from the rotor windings of the second signal device for causing the symbol to move on the first layer of electroluminescent phosphor in a direction and at arate in accordance with the difference in said first and second conditions.

3. The improvement defined by claim 1 including each layer being a circular band, and the electrodes of the first set of the second layer being arranged in spaced relation with the selected transparent resistive material therebetween in the circular band of the second layer so that the symbol moves in a circle in the direction and at the speed in accordance with the sequence and rate of change of the alternating current voltage.

4. The improvement defined by claim 3 in which the second layer includes a second set of an additional plurality of electrodes and additional selected transparent resistive material positioned between said additional electrodes, said second set of the additional electrodes being positioned in said second layer in a spaced axial relation to the first set of electrodes of said second layer, and in which the alternating current means applies alternating current voltages across the second set of additional electrodes of said second layer, the electroluminescent phosphor of the first layer and the third common electrode layer simultaneously with the application of alternating current voltages to the first set of electrodes of said second layer so as to effect a two dimensional display that moves in a direction and at a speed in accordance with the sequence and rate of change in the amplitudes of all the alternating current voltages.

5. The improvement defined by claim 4 in which the voltage amplitude-changing means includes two signal devices, each signal device having a rotor winding energized by an alternating current voltage, each rotor winding being rotatable in accordance with a different condition, and stator windings commonly connected at one end to the third common electrode layer and providing voltage outputs corresponding to the rotathe first layer in accordance with the voltage outputs from the stator windings of the signal devices for causing the symbol on the first layer of electroluminescent phosphor to move in a direction and at a rate in accordance with a difference in said conditions.

Claims

1. In a device for displaying a moving symbol of a type including a first layer of an electroluminescent phosphor having a light emitting threshold voltage level, a second layer positioned at one side of the first phosphor layer, a third common electrode layer positioned at the opposite side of the first phosphor layer; wherein the improvement comprises the second layer including a first set of a plurality of electrodes separated by transparent resistive material selected from a group consisting of stannous chloride, nichrome and gold, means for applying alternating current voltages of different amplitudes related one to the other simultaneously to the plurality of electrodes of the first set of electrodes and to the third common electrode layer, the alternating current voltage applied to one of said plurality of electrodes of the first set of electrodes having an amplitude greater than the light emitting threshold voltage level of the electroluminescent phosphor of the first layer, and the alternating current voltage simultaneously applied to the other of said plurality of electrodes of the first set of electrodes being less than said threshold voltage level, the greater amplitude of the alternating current voltage applied to said one electrode causing the first phosphor layer to emit a band of light to provide a symbol on the first layer of electroluminescent phosphor, and means for changing the amplitudes of the voltages simultaneously applied to said plurality of electrodes of said first set so as to sequentially apply to each one of said plurality of electrodes of said first set an alternating current voltage having an amplitude greater than the light emitting threshold voltage level of the first phosphor layer to cause the emitted light band symbol to move on the first layer of electroluminescent phosphor in a direction and at a speed in accordance with the sequence and rate of change of the alternating current voltages.

2. The improvement defined by claim 1 in which the means for changing the amplitudes of the alternating current voltages across the first layer of electroluminescent phosphor includes a first signal device having a rotor winding energized by an alternating current voltage, the rotor of the first signal device being rotatable in accordance with a first condition, the first signal Device having stator windings providing output voltages in accordance with the rotation of the rotor winding, another signal device having stator windings, the stator windings of said other signal device being connected back to back to the stator windings of the first signal device and energized by the output voltages from the stator windings of the first signal device, and rotor windings of the other signal device being commonly connected to the third common electrode layer, the rotor windings of the other signal device being rotatable in accordance with a second condition to provide output voltages in accordance with a difference in the rotation of the rotor winding of the first signal device and the rotation of the rotor windings of the second signal device, and each rotor winding of the second signal device being connected to a corresponding electrode of the plurality of electrodes of the first set of the second layer to change the voltages across the electroluminescent phosphor of the first layer in accordance with the output voltages from the rotor windings of the second signal device for causing the symbol to move on the first layer of electroluminescent phosphor in a direction and at a rate in accordance with the difference in said first and second conditions.

5. The improvement defined by claim 4 in which the voltage amplitude-changing means includes two signal devices, each signal device having a rotor winding energized by an alternating current voltage, each rotor winding being rotatable in accordance with a different condition, and stator windings commonly connected at one end to the third common electrode layer and providing voltage outputs corresponding to the rotation of the rotor winding; each stator winding of one signal device being connected at other ends to a corresponding electrode of the first set of electrodes of the second layer and each stator winding of the other signal device being connected at other ends to a corresponding electrode of the second set of electrodes of said second layer so as to sequentially change the applied voltages across the electroluminescent phosphor of the first layer in accordance with the voltage outputs from the stator windings of the signal devices for causing the symbol on the first layer of electroluminescent phosphor to move in a direction and at a rate in accordance with a difference in said conditions.