US3710180A

US3710180A - Sequentially addressable display apparatus with means for reversing direction of transfer

Info

Publication number: US3710180A
Application number: US00073456A
Authority: US
Inventors: J Rooks
Original assignee: SCHJELDAHL CO
Current assignee: SCHJELDAHL CO
Priority date: 1970-09-18
Filing date: 1970-09-18
Publication date: 1973-01-09
Anticipated expiration: 1990-01-09

Abstract

A sequentially addressable numerical display system wherein any of a variety of read-out display arrays such as an array of glow tubes or an AC powered load, such as incandescent lamps on a billboard can be illuminated in a predetermined serial fashion to produce a ''''traveling'''' effect. The system comprises a neon glow tube type sequencer with bi-directional capability wherein pulses applied to the sequencer cause the glow tubes to fire in either forward or reverse sequential order to thereby trigger electronic switching means, permitting corresponding sequential energization of the load.

Description

United States Patent 1 Rooks [451 Jan. 9, 1973 [54] SEQUENTIALLY ADDRESSABLE DISPLAY APPARATUS WITH MEANS FOR REVERSING DIRECTION OF TRANSFER [75] Inventor: John C. Rooks, Northfield, Minn.

[73] Assignee: G. T. Schjeldahl Northfield, Minn.

[22] Filed: Sept. 18, 1970 [21] Appl. No.: 73,456

Company,

[52] U.S. Cl. ..3l5/153, 315/845, 315/169 R, 315/169 TV [51] Int. Cl. ..H05b 37/02 [58] Field of Search ..235/92 EV; 307/222, 223; 315/153, 169, 169 TV, 169 T, 84.5; 328/37,

[56] References Cited UNITED STATES PATENTS 3,493,957 2/1970 Brooks ..340/336 STAGE l STAGE 2 3,482,114 12/1969 Marshall ..328/37 X 2,880,934 4/1959 Bensky et al ....235/92 EV 3,437,832 4/1969 Kopetski ..307/223 X Primary Examiner-Roy Lake Assistant Examiner-Lawrence J. Daal Attorney-Orrin M. Haugen [57] ABSTRACT A sequentially addressable numerical display system wherein any of a variety of read-out display arrays such as an array of glow tubes or an AC powered load, such as incandescent lamps on a billboard can be illuminated in a predetermined serial fashion to produce a traveling effect. The system comprises a neon glow tube type sequencer with bi-directional capability wherein pulses applied to the sequencer cause the glow tubes to fire in either forward or reverse sequential order to thereby trigger electronic switching means, permitting corresponding sequential energization of the load.

5 Claims, 5 Drawing Figures STAGE 3 PATENTEDJAH ems 3,710,180

SHEET 1 BF 2 STAGE 1 STAGE 2 STAGE 3 INPUT VC O INVENTOR JOHN C. FOO/(5 ATTORN PATENTEDJAu 9197s 3.710.180

sum 2 0r 2 TO ADDITIONAL I38 OUTPUT STAGES INVENTOR JOHN C. HOOKS ATTORNEY SEQUENTIALLY ADDRESSABLE DISPLAY APPARATUS WITH MEANS FOR REVERSING DIRECTION OF TRANSFER CROSS-REFERENCES TO RELATED APPLICATIONS The present invention is an improvement over those inventions described and claimed in the co-pending applications Ser. No. 23,899, filed Mar. 30, 1970, entitled l BACKGROUND OF THE INVENTION This invention relates generally to visual display apparatus, and more specifically to an electronic control circuit for effecting energization of the display, with the control circuit being coupled to an output load, such as a high direct or alternating current load comprising a plurality of groups of incandescent bulbs, the transfer occurring in a predetermined order so as to give a visual sensation of movement.

Displays of the type described are quite common. Certain billboards, signs, and other information displays incorporate the sequential illumination of light sources to provide for the continuous flow of indicia or for periodic up-dating of the information being displayed. In the past, sequential energization has been accomplished primarily through the use of electromechanical devices such as motor driven contacts or the like. In certain applications, it is desirable to permit the periodic reversal in the lighting sequence of the lamps such as, for example, to eliminate errors without transferring the error across the entire display. Prior art techniques have not readily adapted themselves to this capability. Further, the prior art electro-mechanical arrangements are, relatively expensive and subject to periodic maintenance resulting from failure due to wear.

The display apparatus of the present invention may utilize a solid state triggerable switching device commonly known as a triac, and an alternating current supply in the output. The firing order of the triacs is controlled by an electronic circuit which functions like a ring counter to produce a sequence of output triggering signals with bi-directional capability. The design is such that by merely reversing the sequence of stepping pulses applied to the counter, the order of production of the triggering signals is reversed. Because of the absence of mechanical switching apparatus, the system of the present invention is highly reliable and relatively inexpensive.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved visual display device.

A further object of the present invention is to provide a display device utilizing electronic components throughout and having bi-directional capabilities.

Still another object of the invention is to provide a novel sequentially addressable numerical display system which may be used to control the illumination on incandescent lamps in a predetermined order and direction.

These and other objects of the invention will become apparent to those of ordinary skill in the art upon a study of the following description taken in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of the preferred embodiment of the sequencer used in the system;

8c FIG. 2 illustrates the timing of the stepping pulses applied to the circuit of FIG. 1 to cause the production of trigger pulses in a first order;

FIG. 3 illustrates the timing of the stepping pulses applied to the circuit of FIG. 1 to cause the production of trigger pulses in a second and opposite order;

FIG. 4 is a schematic diagram of one stage of a complete system constructed according to the present invention; and

FIG. 5 is a schematic diagram of one stage of a modified system constructed according to the present invention, and utilizing optical coupling.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is illustrated by means of an electrical schematic diagram, the preferred embodiment of a sequencing circuit constructed in accordance with the teachings of the present invention. As is illustrated, the circuit comprises a plurality of stages which are separated from one another by means of the

dashed lines

10 and 12. While in FIG. 1, only three stages are illustrated, it is to be understood that an additional number of stages may be arranged in identical fashion to that illustrated in order to adapt to the system requirements. As is illustrated, each stage includes a gaseous discharge lamp such as a glow lamp such as the

lamps

14, 16, 18, each having a first electrode thereof connected to a bus 20. The other electrodes of each of the neon lamps are individually connected to

junctions

22, 24 and 26 to which junctions are also respectively connected a first terminal of each of

resistors

28, 30 and 32. The other terminal of

resistors

28, 30 and 32 are connected to a point of fixed potential such as ground 34, or possibly either bus 86 or bus 78.

Also connected to the

junctions

22, 24 and 26 are pairs of diodes. More specifically, in stage 1, the anode electrodes of

diodes

36 and 38 are connected to junction 22. In stage 2, the

diodes

40 and 42 are connected to the junction 24, and in stage 3, the anode electrodes of

diodes

44 and 46 are connected to the junction 26. The cathodes of the

diodes

36, 38, 40, 42, 44 and 46 are coupled through

resistors

48, 50, 52, 54, 56 and 58 respectively to

junctions

60, 62, 64, 66, 68 and 70.

Diodes

72, 74 and 76 respectively connect

junctions

60, 64 and 68 to a common bus 78. In a similar fashion, the

diodes

80, 82 and 84 respectively

couple junctions

62, 66 and to a common bus 86. The input triggering signal is applied at the junction 60 between resistor 48 and diode 72. The output from stage 1 is coupled by means of a capacitor 88 to the corresponding input terminal of stage 2 That is, capacitor 88 couples the output terminal 62 of stage 1 to the input terminal 64 of stage 2. Similarly, a capacitor 90 connects the output terminal 66 of stage 2 to the input terminal 68 of stage 3.

Now that the construction of the circuit of FIG. 1 has been described in detail, consideration will be given to its mode of operation.

The bus is connected to a source of positive potential which is slightly less than the ignition potential of the

neon glow tubes

14, 16 and 18, such as a voltage level of 100-120 volts when Type 3AH are used. Thus, the gaseous discharge or glow lamps are normally in their extinguished state. When a negative going trigger input signal isapplied at the input junction 60 of stage 1, the potential difference across the neon glow lamp 14 is increased and exceeds the firing potential of the lamp. As a result, the lamp is ignited and the potential at junction 22 rises to approximately the value of the bus 20 potential minus the sustaining potential of the neon lamp 14.In order to have the lighted condition of the neon lamps propagate from left to right, the pulse type waveforms illustrated in FIG. 2 are applied to the

common busses

78 and 86. Specifically, the waveform identified as V is applied to the bus 86 while the waveform illustrated as V is applied to the bus 78.

Referring to the waveforms, it can be seen that first in time, the pulse signal applied tobus 86 assumes a positive value at an amplitude above the potential of junction 22 and the diode ceases to conduct. The junction 22, however, remains near the previous value. The current path is now through

diodes

36 and 72. (V is at ground potential.) With diode 80 non-conducting, current momentarily flows from the bus 20 through neon lamp 14, through the diode 38, through resistor 50, through capacitor 88 and through diode 74 to the grounded bus 78. This current flow causes the capacitor 88 to charge up with a voltage having the polarity as indicated by the polarity markings adjacent the capacitor. Next in time, the signal applied to the bus 78 goes from ground potential to a positive voltage equal to that then being applied to the bus 86. When this signal, V reaches its positive value, the potential difference across neon glow tube 14 drops below the extinction potential and it goes out of conduction, since the junction 22 is now at a positive value whereby the glow lamp 14 will no longer remain ignited.

Next in point of time, the signals V and C D simultaneously drop from their positive value back to ground. The negative potential on capacitor 88 when added to the potential on bus 20 is sufficient to exceed the ignition potential of the neon glow lamp l6 and it fires.

As long as the signals V and V are applied in the sequence shown in FIG. 2, the direction of propagation will be from the left to the ,right. To reverse the direction of propagation it is only necessary to reverse the order of appearance of the signals applied to the

busses

78 and 86.

To illustrate, assume that neon glow lamp 18 has, been fired and that the

busses

86 and 78 are at ground potential. Capacitor 90 will be dischargedlsince under the assumed conditions,

junctions

66 and 68 are atthe same potential (ground). Referring to FIG. 3, it can be seen that in point of time, the first event to occur is the positive going excursion of the pulse applied to the bus 78. With bus 78 positive, the diode 76 will not conduct. However, junction 26 will still be coupled to ground potential through the

diodes

46 and 84 and the resistor 58. Therefore, neon lamp 18 will continue to glow. With diode 76 not conducting, a current path is established from bus 20 through neon lamp 18, through diode 44, through resistor 56, through capacitor 90, and through diode 82 to the grounded bus 86. This causes the capacitor to become charged in the manner indicated by the polarity markings adjacent to capacitor 90.

Next, the signal applied to bus 86 assumes a positive value approximately equal to the potential on bus 78. With both

busses

78 and 86 positive, the potential at junction 26 rises toward the potential applied to the bus 20. As a result, the potential difference across neon tube 18 falls below the sustaining potential of the neon lamp and it is extinguished.

Next, the signals on

busses

78 and 86 simultaneously return to the ground or zero volts. Because of the negative voltage applied to junction 66 by virtue of the charge on capacitor 90, only neon tube 16 will fire because it is the only glow tube in the chain that has a potential difference across it of a value exceeding the ignition potential for that lamp.

Thus, it can be seen that the direction of propagation of illumination of the glow lamps has been changed from left-to-right to right-to-left.

Now that the operation of the neon glow lamp sequential triggering circuit has been described, consideration will be given to the manner in which this circuit may be used in a visual display system for controlling the firing of an alternating current load such as one or more incandescent lamps.

Referring to FIG. 4, there is shown one stage of a multi-stage bi-directional sequential triggering circuit of the type illustrated in FIG. 1. Again, the stage includes a neon glow lamp 92 having one terminal thereof coupled through a resistor 94 to the grounded bus 96 which is also one side of the AC line. The other terminal of the neon lamp 92 is connected to a junction 98 formed between the resistor 100, a diode 102, and a diode 104. Diode 102 is connected in series with a resistor 106 and a diode 108 to a common bus 110. Similarly, the diode 104 is connected in series with a resistor 112 and a diode 114 to a common bus 116. The output from this stage is obtained from the junction 118 and is coupled to a succeeding stage of a plurality of stages (not shown) through a capacitor 120. The bus 96 is connected to the ground terminal of an alternating current source which may be nominal line potential of 117 volts AC. The other terminal 122 of the AC source is connected to a load, here illustrated as an incandescent lamp 124. The other terminal of lamp 124 is connected to a solid state triggerable switching device or triac 126. The other power terminal of triac 126 is connected to the grounded bus 96 by a conductor 128. The gate or trigger electrode 130 of triac 126 is coupled through a resistor 132 to the emitter electrode of a transistor 134. The base or control electrode of transistor 134 is coupled by a conductor 136 to the junction 138 formed between the resistor 94 and one terminal of neon lamp 92. The collector electrode of transistor 134 is coupled to a suitable bias potential from an indicated source (not shown).

In operation, when the lamp 92 is extinguished prior to the application of an input triggering signal, the base electrode of transistor 134 will be at approximately ground potential and the transistor will be non-conducting. Upon the application of a negative going input to the junction formed between resistor 106 and diode 108, the ignition potential of the neon lamp will be exceeded and the neon lamp will fire into conduction. As a result, a current flows from the ground bus 96 through resistor 94 and through the neon glow lamp 92 and through the

diodes

102 and 104 and

diodes

108 and 114 to the

negative busses

110 and 116. In the embodiment of Figure, since the bus 96 is at ground potential, the

busses

110 and 116 are cycled between a normal potential of l volts and a potential of -40 volts rather than between ground and +50 volts as described in connection with FIG. 1. However, limitaprimary windings being coupled directly to the AC supply. The secondary winding 146 is grounded at its center tap position, and is connected across

diodes

148 and 150 so as to provide a source of unfiltered DC at 5 junction point 152. Junction point 152 provides a tion to these values is not intended, since component selection may determine the values to be employed. The point 139 of resistor 100 is also connected to the 1 10 volt supply.

When lamp 92 is conducting, the voltage drop across resistor 94 lowers the potential on the base electrode of transistor 134 and it in turn conducts. The PNP transistor illustrated functions as an emitter follower and provides current gain. The emitter terminal follows the voltage applied to the base electrode and provides enough gate current to trigger the triac 126. When the triac fires, its internal impedance is markedly reduced and sufficient current flows from the alternating current source connected to terminal 122 and through the load 124 to energize it.

Upon the extinction of the glow lamp 92 during the normal cycling of the system, the potential applied to the base of the transistor 134 again goes to ground and when the alternating current flowing through the triac goes to zero volt, the triac will turn off and again resume its high impedance state.

Typical component values for the circuits of FIGS. 1 and 4 are given in the following table. By providing such values, however, no intention to limit the invention should be implied.

TA BLE I Embodiment of FIG. 1 R 48 thru R 58 27 kilohms R 28 thru R 32 10 megohms C 88, C 90 0.005 microfarad Diodes 36 thru 46 Type lN9l4 Neon Lamps 14 thru 18 Type 3AI-I V, 1 10 volts (typically 100-120 volts) Embodiment of FIG. 4

R 94 2.2 kilohms R 132 100 ohms Transistor 134 Type 2N5l38 Triac 126 Type 2001p (Electronics Control Corporation) Attention is now directed to FIG. 5 of the drawings wherein one stage of an optically coupled system prepared in accordance with the present invention is illustrated in detail. In this embodiment, a separate output stage is optically coupled to the driver stage, such as the driver stage illustrated in that portion of the circuit identified by the numeral 138 and being disposed to the left of the dashed line. In the output stage shown to the right of the dashed line, a transformer 140 is coupled to a source of ll7-volt AC power, 142, with the supply of uni-directional power to the emitter-collector circuit of transistor 154, emitter 156 being coupled directly to junction 152, with collector 158 being coupled as hereinafter described. The base electrode 160 of transistor 154 is coupled to junction 162, this point being resistively coupled to junction 152 through resistor 163. The collector electrode 158 of transistor 154 is coupled to one terminal of resistor 164, the other terminal being coupled to triac 166 through its control electrode 168. One power terminal of triac 166, that is, terminal 170, is connected directly to ground, while the other power terminal 172 is coupled to the input of load lamp 174, with the other terminal of lamp 174 being coupled to AC source terminal 142.

Junction 162 is coupled to one terminal of photoconductor 176, this photo-conductor being optically coupled to neon lamp 92, with the other terminal of the photocell 176 being coupled to ground through conductor 178. It will be appreciated that photocell 176 is preferably of the photo-resistive type, the impedance of photocell 176 dropping upon exposure to incident radiation.

In operation, the system functions in a manner similar to that system illustrated in FIG. 4, with the exception being the coupling of the input stage to the output stage. In the embodiment illustrated in FIG. 5, when neon lamp 92 is extinguished, the impedance of photocell 176 is high and transistor 154 is rendered non-conductive. Upon sensing incident radiation from lamp 92, the impedance of photocell 176 drops, thus turning transistor 154 on. Current flow through the emitter-to-collector circuit of transistor 154 applies an appropriate signal to the gate or trigger electrode 168 of triac 166. When triac 166 becomes conductive, lamp 174 comes on, and will remain on so long as a signal is applied to the gate or trigger electrode 168.

One significant advantage of this system is the ability to physically separate or segregate the control circuitry from the output arrangements, thus enabling rapid, efficient, and simple maintenance of the system. Accordingly, it is possible to utilize separate arrangements for the control apparatus and the output apparatus. Modular construction is conveniently applied to this arrangement.

For a typical circuit arrangement prepared according to the schematic illustration in FIG. 5, the following values have been found to be desirable for the various components utilized:

Resistor 163 4.7 K

Transistor 1S6 2N5135 Resistor 164 l K Diodes 148 and lN5060 Triac 166 Q2001? (Electronic Controls Company) With continued attention being directed to the schematic illustration in FIG. 5, it has been shown that it is possible to control the intensity of the output applied to lamp 174 by the use of a dimmer-control in the drive circuit. In this connection, a dimmer-control apparatus will be utilized in the supply to the primary winding 144 of transformer 140, thus affecting the current flow to the secondary, and ultimately through triac 166. The dimmer-control functions as a pulsating phase control for the regulation of brightness in the manner conventionally utilized.

The systems of the present invention are useful in the embodiments illustrated, as well as being useful in the embodiments disclosed and claimed in the co-pending applications Ser. No. 23,899 now US. Pat. No. 3,668,641 and 24,159 now US. Pat. No. 3,668,642, identified hereinabove.

It will be appreciated, of course, that the triac devices illustrated in the schematic illustrations are bidirectional and capable of utilizing alternating current. It will be appreciated, of course, that unidirectionally responsive devices such as silicon controlled rectifiers may be utilized in lieu of the triac devices, provided however, that the silicon controlled rectifiers (SCR) are powered with uni-directional or direct current.

lclaim:

l. A circuit for controlling the energization of a multi-element loadsuch that energy is applied to predetermined elements of said multi-elements of said load in a predetermined sequence, said circuit comprising a plurality of stages, each stage being substantially identical and comprising:

a. a load element including a gaseous discharge tube, with the tube having first and second terminals operatively associated therewith, said first terminal being coupled to a point of substantially fixed potential, said discharge tube having a certain ignition potential and a relatively lower sustaining potential;

b. a triac switching device for each of said load ele ments;

0. conductive means individually coupling each of said second electrode terminals of each of said discharge tubes to thereby couple each of said gaseous discharge tubes in series with one of said triac switching devices across an electrical current supply such that when one of said triac switching devices is triggered, current flows through that certain one of the load elements coupled thereto;

d. a triggering network for generating triggering pulses for each of said triac switching devices in said stages and in a predetermined sequence, each of said triggering networks comprising:

1. the gaseous discharge tube of said load element being of the type which fires when the potential thereacross exceeds said ignition potential and which is extinguished when the potential thereacross falls below said sustaining potential;

2. means connecting said first terminal of said discharge tube to a point of fixed potential;

3. input and output circuit means each including a unidirectional current conducting device individually connecting said second terminal of said discharge tube to a certain individual pulse source, each pulse source having pulse outputs with first and second amplitude values; and

4. a capacitor coupled between said output circuit means of one stage and the input circuit means of an adjacent stage, the arrangement be in such that when a first pulse with a certain firs amplitude is applied to said output circuit means current flows to charge said capacitor and when a second pulse with a certain second amplitude is coincidentally applied to said input circuit 4. Apparatus as in claim 1 wherein the trigger electrode of each triac is coupled to one terminal of said gaseous discharge tube for receiving a triggering pulse when said gaseous discharge tube is fired.

5. Apparatus as in claim 1 wherein photo-electrically responsive means adapted to sense the ignition condition of said gaseous discharge tube are provided for delivering a triggering pulse to said trigger electrode.

Claims

1. A circuit for controlling the energization of a multi-element load such that energy is applied to predetermined elements of said multi-elements of said load in a predetermined sequence, said circuit comprising a plurality of stages, each stage being substantially identical and comprising: a. a load element including a gaseous discharge tube, with the tube having first and second terminals operatively associated therewith, said first terminal being coupled to a point of substantially fixed potential, said discharge tube having a certain ignition potential and a relatively lower sustaining potential; b. a triac switching device for each of said load elements; c. conductive means individually coupling each of said second electrode terminals of each of said discharge tubes to thereby couple each of said gaseous discharge tubes in series with one of said triac switching devices across an electrical current supply such that when one of said triac switching devices is triggered, current flows through that certain one of the load elements coupled thereto; d. a triggering network for generating triggering pulses for each of said triac switching devices in said stages and in a predetermined sequence, each of said triggering networks comprising: 1. the gaseous discharge tube of said load element being of the type which fires when the potential thereacross exceeds said ignition potential and which is extinguished when the potential thereacross falls below said sustaining potential; 2. means connecting said first terminal of said discharge tube to a point of fixed potential; 3. input and output circuit means each including a unidirectional current conducting device individually connecting said second terminal of said discharge tube to a certain individual pulse source, each pulse source having pulse outputs with first and second amplitude values; and 4. a capacitor coupled between said output circuit means of one stage and the input circuit means of an adjacent stage, the arrangement being such that when a first pulse with a certain first amplitude is applied to said output circuit means current flows to charge said capaciTor and when a second pulse with a certain second amplitude is coincidentally applied to said input circuit means the potential across said discharge tube falls below said sustaining potential.

2. Apparatus as in claim 1 wherein said load elements are incandescent lamps.

3. Apparatus as in claim 1 wherein the trigger electrode of each triac switching device is coupled to means responsive to the ignition condition of the gaseous discharge tube coupled thereto for delivering a triggering pulse to said trigger electrode.

4. a capacitor coupled between said output circuit means of one stage and the input circuit means of an adjacent stage, the arrangement being such that when a first pulse with a certain first amplitude is applied to said output circuit means current flows to charge said capaciTor and when a second pulse with a certain second amplitude is coincidentally applied to said input circuit means the potential across said discharge tube falls below said sustaining potential.

4. Apparatus as in claim 1 wherein the trigger electrode of each triac is coupled to one terminal of said gaseous discharge tube for receiving a triggering pulse when said gaseous discharge tube is fired.