US 3729731 A
A gas panel display system produces a moving display as a result of movement of at least one set of conductors. A first set of parallel conductors aligned parallel to the direction of motion of the display image is mounted behind a display window in a gas tight display housing which contains an ionizeable gas. A second perpendicular set of parallel conductors insulated from the ionizeable gas is mounted on a moving belt which carries the display image past the window. Information is written into the display by applying ignition pulses to a set of writing electrodes aligned along a line parallel to the conductors of the second set. The ignition pulses ionize the gas between the writing electrodes and the second conductors, thereby creating activated display points along the second conductors. The information written into the activated display points is made visible by applying a sustaining voltage between the conductor sets to sustain a glow discharge in the ionizeable gas at the activated points. An erase roller located just before the writing electrodes erases any remaining, previously written, information.
Claims available in
Description (OCR text may contain errors)
Apr. 24, 1973 United States Patent 41 Konnerth et al.
 ABSTRACT A gas panel display system produces a moving display MOVING GAS PANEL DISPLAY SYSTEM as a result of movement of at least one set of conductors. A first set of parallel conductors a] igned parallel to the direction of motion of the display image is mounted behind a display window in a gas tight dis- Corporation, Armonk, N .Y.
June 23, 1971  Appl. No.: 155,970
play housing which contains an ionizeable gas. A
second perpendicular set of parallel conductors insu-  Filed:
' lated from the ionizeable gas is mounted on a movm W pp y s belt which carries the display image past the windo Information is written into the display by a nition pulses to a set of writing electro 5 0 4 0 L mm 0 ,4 M3 R 2 3w a m 3 5m m3m w C S t U h l l. 2 l 5 5 .l l
des aligned along a line parallel to the conductors of the second set. The ignition pulses ionize the gas between the writing electrodes and the second conductors, thereby  Fleld of Search creating activated display points along the second con- 340/343 324 M; g 3 325;: ductors. The information written into the activated display points is made visible by applying a sustaining voltage between the conductor sets to sustain a glow  References Cited discharge in the ionizeable gas at the activated points.
An erase roller located just before the writing electrodes erases any remaining, previously written, information.
UNITED STATES PATENTS .....3l3/l47 X Coleman et al...................340/324 R 13 Claims, 15 Drawing Figures Gesteland et al.
Primary Examiner-David L. Trafton Attorney-Maurice H. Klitzman et al.
MOTOR CONTROL ENERGlZlNG MEANS Patented A ril 24, 1913 6 Sheets-Sheet 1 INVENTORS KARL L KONNERTH CONRAD LANZA ATTORNEY s Sheets- Sheet s Patented April 24, 1973 FIG WRITING VOLTAGE SUSTAINING 0 VOLTAGE plays.
1 MOVING GAS PANEL DISPLAY SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to the field of electronically changeable information displays, and more particularly to the field of moving electronically changeable information displays.
2. Description of the Prior Art Modern changeable information displays are preferably self-illuminated to assure easy reading of the displayed information independent of the level of general illumination in the vicinity of the display. To assure reliable, long life displays, electronic control over the characters to be displayed is preferred to mechanical control.
Stationary gas panel displays as well as non-gas panel moving displays are well-known in the art. The stationary gas panel displays are comprised of two sets of parallel conductors arranged perpendicular to each other, so that one set determines the X coordinates and the other set determines the Y coordinates of display points. In order to sustain desired glow discharges, a sustaining voltage is applied between the X and Y c'onductors. The magnitude of this voltage must be closely 1 controlled so that the voltage between the X and Y conductors at thepoints where they cross is sufficient to sustain glow discharges which are already in existence, but not so great as to initiate new discharges. A new glow discharge at a selected point is produced by applying half select write voltages to each of the corresponding X and Y lines. These half select write voltages must be closely controlled in amplitude, frequency and timing, in order to assure that the selected glow will be initiated and that no other glows will be initiated. These displays have the disadvantage that they require one driver for each X line and one driver for each Y line of the display.
Among the known moving displays are those comprised 'of many individual light bulbs which are sequentially illuminated to create the illusion of moving characters and changeable mechanical movingbelt dis- Today, particularly in small displays, bulbs are in disfavor because of the power'required to illuminate them and because of the high power switching circuitry necessary for their operation.
One type of prior art mechanical moving belt display is comprised of a matrix in which-each element has two sides of differing colors. A message is written on the belt by turning selected elements of the matrix around to form the desired characters on the viewing face of the matrix. Such displays, unfortunately, are subject to the usual reliability problems of systems containing many moving parts and are not capable of providing self-illuminated displays with electronic control of the characters to be displayed.
OBJECTS OF THE INVENTION The primary object of the invention is to self-illuminate a moving display.
Another object is to provide a moving gas panel display.
Another object of the invention is to stop or reverse a moving gas panel display.
individual light An additional object is to provide a writable gas panel display without requiring close tolerances on the write signals.
A further object of the invention is to provide a gas panel display system with a greatly reduced number of write drivers.
Still another object of the invention is to provide a gas panel display system in which the write signals amplitude, frequency and timing are independent of the sustaining voltage.
SUMMARY OF THE INVENTION The above objects are accomplished by a gas panel I display system in which a first set of preferably parallel transparent conductors aligned parallel to the direction of motion of the display is mounted on the inside of a viewing window and a second perpendicular set of parallel conductors is carried past the viewing window in a first direction by an endless belt. A display point is located where a conductor from the first set and a conductor from the second set intersect. An insulating layer is interposed between the first conductors and the second conductors. The insulating layer is provided so that a writing station located just upstream of the window can activate selected display points along the second conductors by depositing a memory charge on the insulation. Ignition pulses of sufficient voltage to ionize the gas between writing electrodes and the second conductors are applied to selected writing electrodesaligned along a line parallel to the second conductors to activate corresponding display points on the belt. Displayed information is made visible by applying a sustaining voltage between the first and second sets of conductors to support a glow discharge of the ionizeable gas at each activated display point. The insulating layer moves with the second conductors to transport the memory charge and thus the displayed information past the window. The writing electrodes are separated from the first set of parallel conductors to insulate the ignition pulses from the effect of the sustaining voltage and to render the sustaining and writing voltages independent. Undesired information is erased from the display be a conducting erase r'oller in contact with the endless belt just upstream from the writing station.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS Q FIG. 1 is a perspective view of the display unit and a block diagram of the control system.
FIG. 2 is a partially cut-away view of a section of the endless belt and the electrical contacts to it. 7
FIG. 3 is a perspective detail showing the writing station, the viewing window, and the erase roller.
FIG. 4 is a section view of the writing structure taken along the line 44 in FIG. 3.
FIG. 5 illustrates the writing and sustaining voltages.
' FIGS. 6 through 14 are a step by step illustration of the writing into the display of the letter'A and the first part of the letter B. 1
FIG. 15 is a timing diagram showing the sequence of operations in writing the letter A and B in FIGS. 6-14.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT A moving gas panel display unit is shown in FIG. 1. The unit comprises a housing means 102 having a viewing window 104. A first plurality of parallel conductors 108 is disposed behind the viewing window 104 with conductors 108 preferably aligned parallel to the direction of the display motion. Conductors 108 are preferably transparent and mounted on the back of window 104. The individual conductors 108 are connected together by a common conductor 110. The common conductor 110 is connected to an energizing means 195 which supplies a sustaining voltage 212 (FIG. through wire 112.
The energizing means 195 can generate the sustaining signal or can transform a signal such as a line voltage to an appropriate voltage level.
A translating means is disposed behind window 104 within housing 102 for translating a second plurality of parallel conductors 132 past the viewing window 104 to create a moving display. The transport means is comprised of an endless belt 122 and a drive means for revolving the belt. The drive means comprises a pair of belt support rollers 150 and 152, a motor 156 for driving the belt and a magnetic clutch 154 through which motor 156 drives roller 152 to drive the belt. The motor 156 is controlled by a motor control 196 through cable 158. Motor control 196 controls the speed and direction of display movement in accordance with control signals received on cable 197. The rotation of motor 156 is transmitted to driven roller 152by a magnetic coupling 154. One of the elements of coupling 154 is inside the gas tight housing 102 and the other is outside thus enabling the rotation to be transmitted to roller 152 without requiring expensive rotary vacuum seals. Belt 122 is normally driven past window 104 from right to left, since the display is intended to be read from left to right.
The structure of the belt 122 is best seen in FIG. 2. The-belt is comprised ofa backing layer 124 and a front layer 126. The second plurality of conductors 132 is preferably disposed perpendicular to the direction of motion of belt 122 and between the layers of the belt. A display point is created where a conductor 108 from the first set and a conductor 132 from the second set intersect. Throughout this specification'theterm intersection is used to mean a point where conductors of the different sets cross over each other. The individual conductors 132 are connected together by a common conductor 134 having a connecting land 136 extending between the layers of the belt. Connecting land 136 is preferably bent around the bottom and up the back of back layer 124. The part of the connecting land 136 on the back of the back layer is preferably separated into discrete tooth-like timing bars 138 having the same spacing as the conductors 132. A connector brush 140 is attached to housing 102 and makes continuous contact with the connecting land 136. The brush 140 is connected to the grounded input of energizing means 195 by wire 142.
A writing means 160 for activating selected display points along conductors 132 of the second set of conductors is disposed just to the right of the viewing window because the display unit is intended ,for right to left movement of the displayed characters. Writing means 160 is best seen in FIGS. 3 and 4. The writing means is comprised of a plurality of writing electrodes 171-177, one associated with each conductor 108 in the first set. The conductors 108 do not extend as far as the writing electrodes 171-177, but each writing electrode is on the same straight line as its associated conductor 108. Writing electrodes 171-177 are supported by write station support 162 and each electrode is connected by cable 167 to a gated amplifier which controls the writing electrode in a manner to be explained hereinafter. For convenience of the drawings, the display unit is shown as having seven conductors in the first set and correspondingly seven writing electrodes which are numbered 171-177 for clarity in referring to them hereinafter. Writing electrodes 171-177 are connected to amplifiers 201-207, respectively. Selected display points on the belt 122 are activated by applying ignition pulses to the writing electrodes 171-177 corresponding to those display points. The ignition pulses must be of sufficient amplitude to ionize the ionizeable gas between the writing electrodes and the belt, but not so large that the ionization spreads excessively. To assure that only the desired points will be activated, the conductors 108 are terminated so that two display points are interposed between a display point under the end of a conductor 108 and a display point under the corresponding writing electrode. This prevents the ignition pulse from ionizing the gas directly between the writing electrode and the corresponding conductor 108 from the first set. The alignment of the writing electrodes 171-177 with the corresponding conductors 108 is more clearly shown in FIG. 4 which is a section view taken along line 44 in FIG. 3. A writing control means (FIG. 1) contains a plurality of gated amplifiers 201-207, one for each writing electrode 171-177 and a character generator 200 which controls the gating of these amplifiers. Character generator 200 decodes character information received on cable 197 into the control signals necessary for writing the desired character. Each amplifier is connected to ignition pulse generator means 104 and when activated by character generator 200 amplifies ignition pulses produced b generator 194 and transmits the pulses to the corresponding writing electrode. Character generator 200 has one output for controlling each amplifier. The output is a logical one if the corresponding amplifier is to be activated and a logical zero if the amplifier is not to be activated. Character generators performing this function are well-known in the art and will not be further described herein since we have not invented a new character generator.
A timing means controls the pulse generator 194 to restrict the application of ignition pulses 210 to the writing electrodes to times when a conductor 132 from the second set of conductors is in alignment with the electrodes 171-177. This timing means is comprised of a sense means and a timing control means 192. The sense means is comprised of a sensor brush 146 supported by housing 102 for contacting timing bars 138 on the back of belt 122, however it will be understood that any alignment sensing means, including optical means may be used. Sensor brush 146 is connected to timing control 192 by a wire 148. Sense brush 146 senses alignment between a conductor 132 from the second set of conductors and .writing electrodes 171-177 by making contact with a timing bar 138 on the back of belt 122. Timing control 192, responsive to sense brush 146 contacting timing bar 138, triggers ignition pulse generator 194. Those amplifiers of amplifiers 201-207 which are being held in an on condition by character generator 200 amplify the ignition pulse and transmit it to the corresponding writing electrodes 171-177. When sense brush 146 loses contact with a timing bar 138, timing control 192 triggers character generator 200 to advance to its next state. The character generator upon advancing to its next state supplies new outputs for controlling the amplifiers in accordance with the next vertical line to be written. In this manner, pulse generator 194 and character generator 200 are triggered alternatively as sense brush 146 contacts successive timing bars 138.
An erase means deactivates previously activated display points prior to the writing of new information onto the display. The erase means is comprised of an erase roller 180 supported in contact with the front layer 126 of belt 122 by an axle 182. The erase roller 180 has a conductive surface which is connected by contact brush 184 and wire 142 to contact brush 140. The erase roller 180 deactivates previously activated points by neutralizing the charge stored on the belt as the belt moves past the roller. Contact brush 184 and wire 142 connect roller 180 to the second conductors 132 through brush 140 to assure that conductors 132 and roller 180 are at the same potential, thus assuring complete removal of charges from the belt.
A typical writing voltage 210 and a typical sustaining voltage 212 are shown in FIG. 5. The amplitudes of these voltages will depend on the spacing of the electrodes and conductors and on the dielectric characteristics of the front layer 126 of belt 122. The foregoing invention and its advantages will be more fully understood from the following explanation of the operation of the invention.
OPERATION OF A PREFERRED EMBODIMENT OF THE INVENTION Operation of the display system is initiated by energizing motor 156 to drive belt 122. As shown in FIG. 1, the belt is driven to pass the 'display window from right to left. The energizing means 195 is also energized to impress a sustaining voltage such as is shown in FIG. 5 on the first conductor set, the second conductor set being grounded. As the belt 122 passes the erase means 180, any memory charges remaining on the belt are removed to deactivate all display points. The display is now ready to begin displaying information. Each time sense brush 146 contacts a timing bar 138 on the back layer 124 of belt 122, the ignition pulse generator 194 is triggered as is shown in FIG. 15. Until a control signal is received on cable 197 by the character generator 200, all of the gated amplifier 201-207 will be turned off and the ignition pulse will not be passed to any of the writing electrodes 171-177'. After receipt of a character on cable 197, the next character generator trigger pulse from timing control 192 in response to sensor brush 146 losing contact with a timing bar 138 will cause the character generator to activate those amplifiers corresponding to the display points to be activated in the first vertical line of the letter.
For simplicity of the description of the operation of the display, the display is shown one character high.
The characters are written at the right hand edge of the display window 104 and move across window 104 from right to left at a constant speed and disappear from view at the left hand edge of the window. The constant speed is provided by continuously energizing motor 156 to rotate drive roller 152 and the display belt 122 continuously. When a conductor 132 on the endless belt is adjacent to the writing electrodes 171-177, the sense brush 146 makes contact with one of the timing bars 138 on belt 122 and the timing control 192 triggers the ignition pulse generator 194. The ignition pulse is amplified by those amplifiers which have been activated by character generator 200. The amplified ignition pulses 210 are applied to the corresponding writing electrodes 171-177 by the multiple conductor cable 167. The amplitude of the amplified ignition pulses is large enough to ionize the gas between the selected writing electrodes and belt 122. With a negative ignition pulse 210 as shown in FIG. 5, electrons from the ionized gas are attracted to belt 122 and positive ions of the gas are attracted to writing electrodes 171-177. Since the front surface 126 of belt 122 is insulating, the electrons attracted to belt 122 remain on the belt as static charges. The ions attracted to writing electrodes 171-177 obtain electrons from the elec trodes and are deionized. Once ignition pulse 210 is removed, the ionization of the gas between the writing electrodes 171-177 and belt 122 ceases. However, the charge on belt 122 remains and moves with the belt, thereby serving as a memory element which activates the display point in accordance with the outputs of the character generator 200. 1
A visible glow is produced behind viewing window 104 by the sustaining voltage 212 which is applied to the conductors 108 on the back of window 104. As has been explained, the amplitude of sustaining voltage 212 must be high enough to initiate a glow discharge at each activated point, but not so high as to initiate discharges at non-activated points. As the activating memory charges on the belt move behind conductors 108 on window 104, sustaining voltage 212 re-excites the glow discharge in a manner explained hereinafter.
During each half cycle of the sustain voltage, an electric field is developed between the conductors 108 and the conductors 132 through the ionizeable gas however, this field is not strong enough to ionize the gas in the absence of an activating charge. If sustaining voltage 212 is on a negative half cycle when the negative activating charge on belt 122 comes under the influence of sustaining voltage 212 there is no ionization effect until the succeeding half cycle. During the first positive half cycle of sustaining voltage 212 to which a negative charge on belt 122 is subjected, an electric field is built up from conductor 108 on the back of viewing window 104 to the negative charge on belt 122. This field is of sufficient strength to ionize the gas between conductor 108 and the charge on belt 122. The ionization of the gas releases positive ions and negative electrons. The electrons are attracted to the conductor 108 by its positive voltage and the ions are attracted to belt 122 by its negative charge. At the end of the positive half cycle a positive charge is left on belt 122, either due to the attraction and retention of positive ions on the belt or due to the attraction of positive ions to the belt and their extraction of electrons from the belt, leaving a positive static charge on belt 122. On the subsequent negative half cycle of sustain voltage 212, the field between conductor 108 and the positive charge on belt 122 ionizes the gas between the conductor and the charge on the belt. This time positive ions are attracted to conductor 108 and the electrons are attracted to belt 122 and a negative charge is left on the belt at the end of the negative half cycle. The ionization of the gas under the influence of sustaining voltage 212 and a charge on the belt repeats this pattern indefinitely. Thus, during each half cycle of sustaining voltage 212, the sign of the charge on belt 122 reverses.
As belt 122 moves past display window 104 the glow discharge associated with an activated point on the belt moves continuously along the window, because in the preferred embodiment conductors 108 on window 104 are parallel to the direction of motion which enables the glow discharge to retain the shortest distance between conductor 108, and the activated point on belt 122, thus following the display point. If the orientation of the two sets of conductors were reversed so that the stationary conductors 108 were perpendicular to the direction of motion to the display, the glow discharges constituting the display would appear to jump from one conductor on window 104 to the next and could be subject to spreading of the ionization and a consequent destruction of the information being displayed.
The cooperation of sustaining voltage 212 and the charges on belt 122 retains the configuration of activated points on the belt. The displayed information therefore moves across window 104 at the same rate as belt 122. Once an activated point on belt 122 moves out from under the influence of sustaining voltage 212 on conductors 108, the glow discharge at that display point ceases. The charge on belt 122 will slowly dissipate once the charge is no longer under the influence of sustaining voltage 212. However, some of the charge would normally remain when that point on belt 122 returns to the writing station 162 to be written with new information. The presence of this charge would result in improper writing by the writing means 160. For this reason the'erase means (roller 180) is placed just to the right of the writing means to remove charges remaining on the belt and thus assure that all the display points are deactivated before they reach the writing station 162.
To illustrate the writing of characters into the display, the writing of a letter A and the first part of a letter B in a X 7 character format will be followed step-by-step in FIGS. 6-14. FIG. is a timing diagram showing the sequence of events in the writing of these characters and shows the timing of (I) sense brush 146's output, (2) the pulse generator trigger, (3) the character generator trigger and (4) the changes in the amplifier control signals produced by character generator 200. Referring to FIG. 15 throughout the following discussion will aid in comprehension. Now referring to FIG. 6, the location of the writing site is indicated by the arrow marked 162. The location of the seven vertical display points are indicated by the positions of the amplifiers 201-207 to the right of the writing site. The amplifiers which are activated by the character generator are shown in black. The unactivated amplifiers are shown in outline. The ionization created by the amplified ignition pulse at each selected display point is indicated by the symbol shown at 220 in FIG. 6. The symbol for an activated display point which has not reached a conductor 108 and thus is not the site of a present glow discharge is shown at 222 in FIG. 7. The symbol for a glow discharge at a activated point in response to sustaining voltage 212 is shown at 224 in FIG. 9.
The writing of the character A is begun by the character generator 200 receiving an electronic symbol for character A on cable 197 as shown in FIG. 15. Subsequently the sense brush 146 loses contact with a timing bar 138 on the back of belt 122 and timing control 192 supplies a character generator trigger to character generator 200. In response to the character generator trigger, the character generator 200 activates those amplifiers corresponding to display points to be activated in the first line of the letter A. (A This is shown in FIG. 6 where amplifiers 202 through 207 are activated. When sense brush 146 makes contact with the next timing bar 138, one of the conductors 132 in belt 122 is aligned with the writing electrodes 171-177 (write station 162). The contacting of timing bar 138 by brush 146 causes timing control 192 to trigger ignition pulse generator 194. Each activated amplifier 202-207 amplifies the ignition pulse and applies it to the corresponding writing electrodes 172-177. In response to the ignition pulses on writing electrodes 172-177, the gas between each of these electrodes and belt 122 ionizes and'deposits an activating negative charge on belt 122. The ionization of the gas at these points is indicated in FIG. 6 by the symbols at 220. After the ignition pulses cease, the ionization between writing electrodes 172-177 and belt 122 ceases and activated display points corresponding to the previous ionization remain as shown in FIG. 7. Brush 146 subsequentially loses contact with that timing bar 138 causing timing control 192 to trigger character generator 200 which changes the state of the amplifiers to that shown in FIG. 7 where only amplifiers 201 and 204 are activated. On the next contact of brush 146 with a timing bar, the next conductor 132 is aligned with the writing electrodes and an ignition pulse is generated. Ignition pulse 210 is amplified by amplifiers 201 and 204 and applied to writing electrodes 171 and 174 causing the ionization of gas between electrodes 171 and 174 and belt 122 as shown in FIG. 7. As shown in FIG. 7, the previously activated display points corresponding to the first line of the letter A are not yet under the influence of the sustaining voltage 212 and therefore do not have glow discharges associated with them. This lack of ionization is to prevent the spreading of the ionizations caused by the ignition pulses 210 which would obscure desired information and write erroneous information. Once the gas between electrodes 171 and 174 and belt 122 is ionized, ignition pulse 210 ceases and the ionization ceases and activated display points corresponding to the ionizations remain as shown in FIG. 8. Sense brush 146 loses contact with that timing bar 138 causing character generator 200 to activate amplifiers in accordance with the third line (A of the letter A. The
third line of the letter A is identical to the second line and therefore no change in the state of the amplifiers takes place. As can be seen in FIG. 8, once again, writing electrodes 171 and 174 corresponding to amplifiers 201 and 204 activate display points on belt 122. The
operation of the display continues in the same fashion. As shown in FIG. 9 for the fourth line of letter A, am plifier 201 and 204 are activated thus activating the corresponding display points on belt 122. As shown in FIG. 9, when the belt is in position for the writing of the fourth line (A of the letter A, the first line (A,) of the letter A has come under the influence of sustaining voltage 212 on conductors 108 and the activated display points in the first line have been re-excited in the manner explained above.
In FIG. 10, the amplifiers are shown activated for the writing of the fifth and last line of letter A. Amplifiers 202-207 are activated to activate the corresponding display points. Here both the first and second lines of letter A are under the influence of sustaining voltage 212 on conductors 108 and therefore have been reexcited and glow to create a visible display. As shown in FIG. 11, no amplifiers are activated for the first line following letter A, in order to provide a space between the letter A and the subsequent letter (B). At this point, the first three lines of letter A are creating a visible display. In FIG. 12, the first four lines of the letter A are shown creating a visible display and the amplifiers are all shown unactivated to leave a second displayless line separating letter A from letter B. In FIG. 13, the entire letter A is creating a visible display and the amplifiers 201-207 are shown activated for writing the first line of letter B. In FIG. 14, the letter A is completely visible as it was in FIG. 13. The activated display points for the first line of letter B are shown in FIG. 14 and the amplifiers are shown activated for writing the second line of letter B. Amplifiers 201 and 204 and 207 are activated in order to activate the corresponding display points. The writing of letter B and other characters proceeds in the above fashion.
The display system of the invention provides many benefits. First, the display is a self-illuminated moving display. Second, the tolerances on the writing voltage is more relaxed then in stationary gas panel display systems using half-select writing because at the time that a display point is activated by an ignition pulse the displaypoint is not under the'influence of the sustaining voltage and therefore the sustaining voltage cannot support a spread of the ionization caused bythe ignition pulse. Therefore, the ignition pulse 210 can be larger than it could be in the presence of the sustaining signal 212. Because the sustaining signal is not in the vicinity of the ignition pulse, the ignition pulse does not need to be coordinated in frequency, amplitude or time with the sustaining voltage.
If desired, the display can be stopped by de-energizing motor 156. The display can even be backed up by running motor 156 backward, if it is desired to remove an erroneous letter. As the display backs up, the belt will carry the erroneous letter under erase roller 180 which will remove the erroneous letter. The motor is then re-energized and the proper letter can be written as the belt moves in the forward direction. The speed of the display can be varied at will by varying the speed of motor 156. The use ofa DC motor makes control of the speed of the motor quite feasible. By providing a motor speed control on the display panel the viewer can control the rate at which information is displayed, thus a fast reader can speed the display up to obtained a maximum amount ofinformation in a minimum time.
The display of this invention, when run at high speed, will be easier to read than displays having sequentially illuminated bulbs or spots because the glow discharge in this invention moves continuously, smoothly and without jumping along conductors 108 on window 104 as has been explained above.
Many variations can be made in the above preferred embodiment. If it is desired to have a bi-directional display, information may be written into the display from either direction by providing a second writing station at the left hand edge of window 104. In another variation in the writing system all displayed points in alignment with the writing electrodes 162 could be activated simultaneously and the non-desired display points thereafter selectively erased, Although this method is not preferred, it is deemed to be within the scope of the attached claims.
Although for convenience of description, the preferred embodiment was shown displaying a single line of characters, any number of lines can be displayed by such a system and the number of display points used in the display of a character depends only on the number of lines available and the versatility of the character generator.
While the invention has been particularily shown and described with reference to a preferred embodiment and variations thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope ofthe invention.
I. A moving display gas panel display system comprising:
a display housing having a viewing window;
a first plurality of parallel conductors disposed behind the viewing window;
a second plurality of parallel conductors substantially perpendicular to the first plurality, and intersecting therewith to form a display point at each intersection;
translating means for translating at least the second plurality of conductors past the display window to create a moving display;-
an ionizeable gas in the vicinity of the display points for supporting a glow discharge;
writing means for activating selected display points along conductors of the second plurality to display 1 information, and;
energizing means connected between the first and second conductors to sustain a glow discharge in the ionizeable gas at activated display points.
2. The apparatus of claim 1 where the second cohductors are separated from the first conductors by an insulating layer which moves with the second conductors.
3. The apparatus of claim 1 wherein:
the tranlating means comprises an endless belt and a drive means for revolving the belt, and;
the second plurality of parallel conductors are mounted on the endless belt.
4. The apparatus of claim 3 wherein:
the first set of parallel conductors is mounted on the inside of the display window, and;
the display housing is gas tight for containing the ionizeable gas.
5. The apparatus of claim 3 wherein the writing means comprises:
a plurality of writing electrodes, one associated with each conductor in the first set;
pulse generating means for supplying ignition pulses to the writing electrodes, and;
control means for selectively connecting the pulse generating means to the writing electrodes to selectively activate display points on the belt.
6. The apparatus of claim 5 wherein the energizing means applies a sustaining voltage between the first and second pluralities of conductors to sustain a glow discharge in the ionizeable gas.
7. The apparatus of claim 5 further comprising:
erase means for deactiving display points prior to writing new information onto the display.
8. The apparatus of claim 5 further comprises:
timing means for controlling the pulse generator to restrict the application of ignition pulses to the writing electrodes to times when a conductor from the second plurality is in alignment with the electrodes.
9. The apparatus of claim 8 wherein the timing means comprises:
sense means for sensing alignment between a conductor of the second plurality and the writing electrodes, and;
timing control means responsive to the sense means for triggering the pulse generating means.
10. The apparatus of claim 9 wherein the first plurality of conductors is aligned parallel to the direction of motion of the display.
11. A moving display gas panel display system comprising:
a gas tight display housing having a viewing window and containing an ionizeable gas;
a first plurality of parallel conductors mounted on the inside of the display window and parallel to the direction of motion of the display;
a second plurality of parallel conductors substantially perpendicular to the first plurality, a point of closest approach of a conductor from the first plurality of conductors to a conductor from the second plurality of conductors being referred to as a display point;
a driven endless belt supporting the second set of conductors for movement past the window to create a moving display, the conductors being aligned perpendicular to the direction of motion of the belt and the side of the second conductors belt; energizing means connected between the two sets of conductors to supply a sustaining voltage to sustain a glow discharge between the first plurality of conductors and the activated display points on the moving belt; sense means for sensing alignment between a conductor of the second plurality and the writing electrodes, and; timing means responsive to the sense means for triggering the pulse generating means to apply ignition pulses to the writing electrodes while the writing electrodes are aligned with a conductor from the second plurality, and; an erase roller for deactivating previously activated display points prior to writing new information. 12. A method of operating a gas panel display system comprising the steps;
applying an ignition voltage between a writing electrode exposed to an ionizeable gas and an insulator exposed to the ionizeable gas to ionize the gas between the electrode and the insulator; retaining a charge on the insulator as a result of the ionization to activate that point on the insulator; applying a sustaining voltage to a conductor exposed to the ionizeable gas in the vicinity of the insulator to cause the gas in the vicinity of any activated points on the insulator to ionize; reversing the sign of the charge on the insulator each time the ionizeable gas is ionized by the sustaining voltage to retain the activation of the point on the insulator. 13. The method of claim 9 further comprising the step of moving the insulator past the conductor which is exposed to the ionizeable gas, thereby moving the display.