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Publication numberUS3859559 A
Publication typeGrant
Publication dateJan 7, 1975
Filing dateFeb 20, 1973
Priority dateMay 3, 1971
Publication numberUS 3859559 A, US 3859559A, US-A-3859559, US3859559 A, US3859559A
InventorsDavid Glaser
Original AssigneeBurroughs Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
System for operating multiple position display tubes
US 3859559 A
Abstract
The disclosed system is adapted for operating multiple position display devices having a plurality of groups of display cathode segments or elements positioned side-by-side, with corresponding elements being electrically interconnected and each group having an associated anode, and an auxiliary electrode common to all of the groups of electrodes for preventing spurious glow about them. The drivers for the anodes are coupled in parallel through suitable impedances to a common impedance from which is taken proportional potential for biasing the auxiliary electrode responsive to the pulsed operation of the anodes. The cathode drivers are also optionally coupled to the common impedance or the auxiliary electrode itself for negatively influencing the auxiliary electrode potential as a function of the number of cathode segments being energized, to aid in preventing spurious glow during operation of the device at high current levels.
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United States Patent 1191 Glaser Jan. 7, 1975 SYSTEM FOR OPERATING MULTIPLE [57] ABSTRACT POSITION DISPLAY TUBES 7 51 Inventor; David Glaser Greenbmbk Ni The disclosed system is adapted for operating multiple position display devices having a plurality of groups of [73] Asslgnee: P' corpmatmnt Detroltt display cathode segments or elements positioned sideby-side, with corresponding elements being electri- [22] Filed: Feb. 20, 1973 cally interconnected and each group having an associated anode, and an auxiliary electrode common to all [21] Appl- 333,496 of the groups of electrodes for preventing spurious Rehted Application Data glow about them. The drivers for the anodes are cou- [63] Continuation of Ser. 139 543 May 3 1971 pled in parallel through suitable impedances to a comabandone mon impedance from which is taken proportional po tential for biasing the auxiliary electrode responsive to [52] Cl 315/169 TV, 315/169 R, 340/336, the pulsed operation of the anodes. The cathode driv- 3l3/517 ers are also optionally coupled to the common imped- 51 Int. Cl. H05b 37/00 or the auxiliary Ode itself negaive'y 581 Field of Search 313/109, 5, 210; fluencing the auxiliary electrode Potential as a func- 315/169 TV, 169 340/336 tion of the number of cathode segments being energized, to aid in preventing spurious glow during opera- [56] References Cited tion of the device at high current levels.

UNITED STATES PATENTS 3,509,420 4/1970 Ogle 315/169 R X Primary Examiner-I-Ierman Karl Saalbach Assistant ExaminerLawrence J. Dahl Attorney, Agent, or FirmGeorge L. Kensinger; Kenneth L. Miller; Robert A. Green Claims, 3 Drawing Figures SEQUENCER 1210 13 253 Is 293 251 258 k 291 298 A V W230 t 2| 14o s A r\ l 0 2| 4| 51 9| i 3,859,559 SHEET 10F 2 PAT-ENTED 7 I975 ATTORNEY PATENTEDJAN 1% sum 2 or 2 mmUZm30mm INVENTOR.

DAVID GLASER ATTORNEY SYSTEM FOR OPERATING MULTIPLE POSITION DISPLAY TUBES This is a continuation, of application Ser. No. 139,543, filed May 3, 1971, now abandoned.

BACKGROUND OF THE INVENTION The subject invention relates to a system for operating multiple position display panels having a plurality of interconnected cathode elements for displaying characters in one or more rows. More particularly, the invention relates to the operation of multiple position gas discharge devices having segmented cathode electrodes and a plurality of individual anode electrodes for displaying characters side-by-side.

A multiple position display device which is available commercially is known as the PANAPLEX numeric panel display. Such display panels include a plurality of groups of cathode elements in the form of elongated bars or segments. Each group of segments is configured in a figure 8 pattern or the like and the various segments can be energized in different groups, together with an anode, to represent different characters as selected positions in the device. Electrical discharge in the device at the selected group of electrodes ionizes the gas and results in cathode glow about the cathode elements which displays the desired character.

Some such display devices include an auxiliary electrode which is common to all the groups of electrodes and is to be biased at a potential intermediate the cathode and the anode potentials to prevent spurious glow in the, device as described in Harvey, et al., Ser. No. 78,045, filed Oct. 5, 1970, now abandoned. Under some circumstances, however, spurious glow sometimes develops in an adjacent group of electrodes or between adjacent electrode groups when a particular anode is energized. Only one group of cathode segments should glow at such time.

These problems were solved satisfactorily for many conditions of operation in Holz and Dieterman Ser. No. 85,662, filed on Oct. 30, 1970, in G. E. Holz Ser. No. 87,058, filed Nov. 5, 1970, and in E. L. Harvey Ser. No. 126,825 and Doane, et al., Ser. No. 126,825, filed on Mar. 22, 1971.

However, under some circumstances, and particularly when the cathodes are driven at high levels of current for a brighter display, spurious glow still occurs. Also, separate circuitry was provided in these applications for biasing and limiting the potential on the cathode and auxiliary electrodes separate from the anodes. This tends to be costly to implement.

SUMMARY OF THE INVENTION Accordingly, an object of this invention is to improve spurious glow suppression in mulitple position display devices having interconnected cathode elements or segments.

Another object of the invention is to further simplify and reduce the cost of systems for operating multiple position display devices having auxiliary electrodes for spurious glow suppression.

In accordance with the invention, a system for operating multiple position display devices includes a driver for each anode coupled in parallel through suitable impedances to a common impedance from which is taken a proportional biasing potential for application to the auxiliary glow suppression electrode. The potential applied to the auxiliary electrode follows the pulsed operation of the anodes for preventing spurious glow among the display electrodes. No steady-state or DC biasing potential, accordingly, need be applied to the auxiliary electrode either initially or during operation of the display control electrodes.

Additionally, each of the electrode drivers is also optionally coupled to the common impedance means for reducing the auxiliary electrode potential as a function of the number of cathode segments being energized. This improves the suppression of spurious glow in the device and permits the use of higher current levels without spurious glow about the electrodes than otherwise possible, which provides a brighter display of the desired characters or symbols.

DESCRIPTION OF THE DRAWINGS These and other advantages and features of the invention are made clear in the following detailed description relating to the attached drawings wherein:

FIG. 1 is a perspective view of a portion of 21 segmented cathode display tube having individual anodes and an auxiliary electrode adapted to be operated by the system of the invention;

FIG. 2 is an elevational view of a longitudinal section of the display panel or tube of FIG. 1; and

FIG. 3 is an electrical schematic diagram of the system of the invention, including a schematic representation of the display device being operated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principles of the invention are particularly applicable to operation of the type of display device described and claimed in the Harvey, et al., patent application Ser. No. 217,781, filed Jan. 14, 1972. Some of the features of such a device are shown in FIGS. 1 and 2 ofa display panel or tube 10 having three representative display positions. A plurality of groups of cathode segments 41-47, 5157, 61-67, are connected to corresponding conductors 21-27 which are insulated from each other on an insulating base plate 20 or within grooves in its surface as shown in FIG. 2. An anode electrode 140, 150, 160, is provided or each group of cathode segments. An insulating sheet or layer 30 shields cathode conductors 21-27 from the anodes, as shown in FIG. 2, to prevent them from glowing.

The anodes in FIG. 1 are each shown as a ring surrounding the associated group of cathodes, but they may be screen electrodes situated above the associated cathode groups, or they may take any other desired shape. In addition, the device includes an auxiliary electrode 230 in the form of a screen disposed above the groups of cathodes and anodes and electrically associated with all of the electrode groups. Top and bottom insulating plates 200 and 20, respectively, sealed together by glass or ceramic frit 15 or the like, complete the panel or tube structure.

Briefly, in operation of the display device shown in FIGS. 1 and 2, drive signals are applied to the cathode via conductor 21-27 in accordance with the input information. Simultaneously, the anodes are energized in turn from left to right, or in any other desired order or sequence via leads 34, 35, 36, in synchronism with the cathode drive signals to cause the cathode segments in the selected groups to glow. A suitable bias potential intermediate the cathode and anode bias potentials is applied to lead 235 of screen electrode 230 for preventing spurious glow about the cathode segments and between adjacent display positions; The biased auxiliary electrode prevents extraneous discharges from occurring between an energized anode and the cathodes in adjacent groups which have operating potential applied to them.

A preferred embodiment of the invention is illustrated in FIG. 3 in which display device l'is shown schematically. Display segments 41, 51, 91 are connected to cathode conductor 21 which is driven from the collector of transistor 121. Likewise, cathode segments 42-92 through 47-97 are connected to the collectors of cathode drivers 122-127 by conductors 22-27, respectively. Cathode conductors 21-27 are also coupled to one end of common resistor 19 at circuit junction 16 by resistors 111-117, respectively. The other end of resistor 19 is grounded, as shown.

The base electrode of cathode driver transistors 121 through 127 are connected to the ouput terminals of data source 100, respectively, for receiving positivegoing information signals. The emitter electrodes of cathode drivers 121-127 are coupled to the anode of diode 130 by current-limiting resistors 9 1-97, respective ly. The cathode of diode 130 is connected to a reference potential terminal 135, as shown.

Anode lead 34 of anode 140 is connected to the collector electrode of anode driver transistor 240. Similarly, anode leads 35-39 of anodes 150-190 are connected to the collector electrodes of anode drivers 250-290. Anode leads 34, 35, 39 are also coupled to the end of resistor'19 at circuit junction 16 by resistors 248, 258, 298, respectively. The emitter electrodes of anode drivers 240, 250, 290 are biased from E reference terminal 12 through forward-biased diodes 13, the anodes of which are connected to the E reference terminal as shown.

Anode drivers 240-290 are controlled by sequencing circuit or device 210. The base electrodes of the anode drivers are coupled to the output terminals of the sequencer 210 by the series connection of resistor 241 and capacitor 244, resistor 251 and capacitor 254, resistor 291 and capacitor 294, respectively. The base electrodes of the drivers 240-290 are biased by resistors 245, 255, 295 and diodes 246, 256, 296, respectively, to E reference potential terminal, as shown.

Coupling capacitors 244, 254, 294 provide DC level-shifting of the control signals applied to the anode drivers. They permit sequencing circuit 210 to be operated at the same signal and bias .levels as data source 100 and cathode drivers 121-127, despite the different DC bias levels in the anode and cathode circuits, themselves. This is necessary when integrated circuits or common transistor circuits are utilized in the signal sources.

Diodes 242, 252, 292 have their cathodes connected to the junction of the series input resistors, and capacitors 241 and 244, 251 and 254, 291 and 294, for clamping the anode control signals in the negative direction to the potential limit applied to their anodes from terminal 225. Diodes 243, 253, 293 have their anodes coupled to the junction of the respective input coupling resistors and capacitors to clamp the positivegoing anode control signals at ground, as shown.

Auxiliary electrode 230 is usually biased at a potential intermediate the anode bias potential E and the cathode bias potential E The bias potential for the auxiliary electrode is usually taken from a voltage source having considerable internal impedance or from a voltage divider or the like coupled to the anode or cathode bias terminal. During operation, auxiliary electrode 230 then conducts a leakage current from whichever anode electrode -190 that is energized, into the associated voltage source or divider. This raises the potential on the auxiliary electrode as more cathode segments are energized or as the cathodes are activated more rapidly. In certain improved circuits the cathode drivers are also coupled to the voltage divider or bias impedance for biasing the auxiliary electrode as an inverse function of the number of cathode segments that are being energized.

In the present invention, electrode 235 of auxiliary electrode 230 is coupled to circuit junction 16 between the anode drivers and resistor 19 by resistor 237. Any other suitable impedance device may be substituted for resistors 19 and 237, if desired.

The bias potential that is applied to auxiliary electrode 230 through resistor 237 is determined by the current in resistor 19. The current for resistor 19, in turn, is conducted by whichever anode driver 240-290 is energized. If the anode drivers are not activated, then the potential at circuit junction 16 and on the auxiliary electrode may float at some intermediate level. This is not deleterious, however, since under this condition no information is being displayed by the device. Each time ananode driver is actuated to display a symbol, current is conducted to resistor 19 and the auxiliary electrode is biased. This bias on the auxiliary electrode follows the pulsed or sequential operation of the anodes and becomes nearly continuous when they are operated in rapid succession.

The amount of current conducted by common bias resistor 19 is determined by its value and the values of resistor 237 and of resistors 111-117, if they are used, which shunt each other in parallel when cathode drivers 121-127 are activated. The potential between E reference terminal 12 and ground is divided across resistor 248, 258, 298, depending on which anode driver is activated, and resistor 19. The major current path for the common bias resistor is, therefore, through the conducting anode driver. Another current path which raises the potential on auxiliary electrode 230 is from the selected anode driver through its anode to the auxiliary electrode, resistor 237, and resistor 19. The magnitude of this current is determined primarily by the values of the resistors since the anode drivers are normally saturated when activated, thus operating as voltage switches.

It is the potential across common bias resistor 19 which primarily biases auxiliary electrode 230 as mentioned above. An auxiliary current path, however, is established from the conducting anode driver through the associated resistor 248, 258, 298, coupling resistor 237 and auxiliary electrode 230 to the energized cathodes and the corresponding activated cathode drivers 121-127. Another auxiliary current path is from the conducting anode driver through the associated resistor 248, 258, 298 and one or more of coupling resistors 111-117 to the activated cathode driver(s) 121-127. These auxiliary current paths shunt or bypass common bias resistor 19 and, therefore, tend to drop the potential at circuit junction 16 and on the auxiliary electrode230 as an inverse function of the number of cathode segments which are energized.

The theory of operation of the inventioh is quite complex, but it is believed to be as follows. As panel is operated and each character position is energized, positive column glow tends to'and often forms between the newly energized anode and cathbdeswhich had been energized at the prior character position and are now turned off. This is undesirable spurious glow. The auxiliary electrode 230, by assuming a generally negative or cathode potential (proportional to the number of cathodes which glow) as each character position is operated, shields" each arfode from prior cathodes and prevents positive column glow.

Either of these auxiliary current paths through coupling resistor 237 or. through pull-down resistors 111-1 17 may be utilized satisfactorily in some conditions. In high current operation of the device for a brighter displayiboth of them may be used. If both auxiliary current paths are relied upon, it should be noted that pull-down resistors 111-117 may be alternatively connected directly to lead 235 of auxiliary electrode 230 rather than to the common bias resistor at circuit junctipn 16, if desired.

Although the preferred embodiment of the invention h 0 been described in detail, it should be understood z rthat the present disclosure has been by way of example i only. Many modifications and, variations of the invention are possible in light of the above teachings. It is,

-therefore, to be understood that the invention may be practiced otherwise than as specifically disclosed.

What is.claimed is: v v i v l. A character display circuit for displaying any one of a plurality of characters in each of a plurality of sideby-side character positions, comprising i v a plurality of anodes, one in each of said character positions,

a plurality of groups of cathodes, each such group.

being associated with one of said anodes and being located in one of said character positions','ea ch of cathodes selectively in response to a first set of input signals, v a plurality of anode selection circuits for selectively energizing said anodes, in synchronism with the selective energization of said cathodes, in response to 1 a second set of input signals, for displaying selected characters in each of said character positionsgby means of current flow from each anode through said gas atmosphere and through the selected cathodes which make up said selected characters,the' magnitude of current flow at each character posibias circuit means for establishing a dynamic voltage bias on said auxiliary electrode,

said bias circuit means including impedance means connected electrically in series with all of said anode selection circuits for developing a bias voltage each time any one of said anode selection circuits is energized by an input signal and current flows therethrough, and circuit means electrically connecting said impedance means to said auxiliary electrode for supplying such bias voltage to said auxiliary electrode, and

circuit means connecting each said cathode driver across at least a portion of said impedance means, so as to modify the effective impedance connected to said auxiliary electrode as each such cathode driver energizes one of said cathodes.

2. A character display circuit as in claim 1 wherein the plurality of anodesand the plurality of groups of cathodes are all located within a common gas-tight envelope,

and wherein the auxiliary electrode is a single electrode associated with each of the character positions and in operative relation to the cathodes and anodes in each such character position.

3. A character display circuit as in claim 2 wherein the auxiliary electrode contains a portion extending between the anode and cathodes of each character position and those of the next adjacent character position, to electrically isolate the electrodes of the respective character positions from each other.

4. A characer display circuit as in claim' 1 further including second bias circuit means for dynamically biasing said cathodes with biasyoltage pulses when said cathodes are not glowing, v i a,

i said second bias circuit means includinga plurality of biasing resistors, one for. each of said cathode conductors, each connected between said impedance means and a different one of said cathode. conductors.. 5.- A character display circuit as in claim 4 wherein the cathode drivers are transistors, each connected to one of said cathode condutors, andv I wherein each such transistor and-the biasing resistor which is connected to the same cathode conductor are connected in series, and each of these resistortransistor series circuits is connected acrossat least a portion of said impedance means. 6. A character display circuit for displaying any one ofa plurality of characters in each of a plurality of sideby -side character positions, comprising an envelope formed of a front plate with a viewing window and a rear plate, said plates being sealed I together along a predetermined perimeter surrounding the side-by-side character positions to establish a gas tight, enclosure,

an ionizable gas within said enclosure at a pressure capable of sustaining a cathode glow discharge,

a plurality of anodes one in each of said character positions within said envelope, Y

a plurality of groups of cathodes, each such group being associated with one of saidanodes and being located in one of said characer positions, each of the cathodes having the shape of a segment of oneof the characters to be displayed,

a plurality of elongated conductors extending within said envelope, each electrically connected to one of the cathodes in each character position, and

each connected electrically to a terminal outside said envelope for connection to an external circuit,

insulating material separating each of said conductors from all of the cathodes except the'cathode in each character position to which such conductor is connected,

anode selection means for energizing said anodes sequentially and cathode selection means for simultaneously selectively energizing different combinations of said cathode conductors sequentially, in synchronism with the sequential energization of the anodes, to form a side-by-side character display over all of said character positions, there being a current flow path from each anode through said ionizable gas in said envelope to its group of cathodes, with the magnitude of current flow at each character position as the anodes and cathodes are energized being generally proportional to the number of cathodes which are energized,

an auxiliary electrode associated with each of said character positions and including a portion disposed between each anode and its group of cathodes and an adjacent anode and its group of cathodes whereby each anode is shielded from the adjacent group(s) of cathodes,

bias circuit means for establishing dynamic voltage bias on said auxiliary electrode, said circuit means including at least one impedance device connected to said auxiliary electrode and connected electrically in series with each such anode selection means for supplying to said auxiliary electrode a series of bias voltage as said anodes are sequentially energized, one such voltage being generated during the energization of each anode, each such bias voltage being inversely proportional to the number of cathodes which glow at each character position, and

circuit means connecting said cathode drivers across at least a portion of said impedance device so as to modify the effective impedance connected to said auxiliary electrode as each cathode driver is energized.

7. A character display circuit as in claim 6 wherein the bias circuit means serves to bias the auxiliary electrode to a predetermined electrical potential for isolating the anode and cathodes of each character position from those of all the other character positions, and

wherein as each cathode driver is energized, it reduces the effective impedance connected to the auxiliary electrode.

8. A voltage compensated dynamic bias circuit for an auxiliary electrode in the gaseous atmosphere of a character indicator tube for displaying side-by-side characters, the tube having a plurality of anodes, one in each character position, and a plurality of groups of cathodes each located in one of the characters positions, the cathodes in each group each being in the shape of a segment of a character to be displayed, ineluding first circuit means including a pluralityof cathode conductors each making electrical connection to one of the cathodes in each character position,

a plurality of cathode drivers, each connected to one of said cathode conductors, for energizing different combinations of said cathodes in response to different combinations of electrical signals received by said cathode drivers,

anode selection circuit means for sequentially energizing said anodes, in sychronism with the selective energization of said cathodes, for displaying selected characters in each of said character positions,

bias circuit means for establishing a dynamic voltage bias on the auxiliary electrode, said circuit means including impedance means connected electrically to each of said anode selection circuits for developing across said impedance means a series of bias voltage signals as the anodes are sequentially energized, one such signal being generated during the energization of each anode, and circuit means clectrically connecting said impedance means to said auxiliary electrode to supply such series of bias voltage signals to said auxiliary electrode, and

circuit means connecting said cathode driver across at least a portion of said impedance means so as to modify the effective impedance connected to said auxiliary electrode as each cathode driver is energized.

9. Multiple-position display device and system for op erating the device, said device comprising a gas-gilled envelope including a plurality of groups of cathode electrodes and an anode electrode associated with each said group, each such group of cathode electrodes and its anode electrode comprising a character position in said display device, corresponding cathodes of the different groups being interconnected by a single common conductor, there thus being a single common cathode conductor for each cathode electrode in each of said groups, and an auxiliary electrode in operative relation with all of said groups of cathode electrodes and their anode electrodes and including a portion disposed between each anode and the adjacent groups of cathodes to act as a shield therebetween, said system comprising a separate anode driver circuit connected to each said anode electrode in said display device,

a sequencing circuit coupled to all of said anode drivers for turning each one on separately and in turn whereby each anode can be connected in circuit with a selected group of cathode electrodes,

a separate cathode driver circuit connected to each of said common cathode conductors, each such driver circuit thus being connected to the same corresponding cathode in each of said groups of cathodes,

a source of data signals coupled to said cathode driver circuits for energizing a selected group of cathodes as each anode is connected in circuit, and

a common impedance connected in circuit with all of said anode drivers and with all of said cathode drivers and with said auxiliary electrode whereby at each said character position in said display deivice when a character is displayed by a selected number of cathode electrodes, a bias voltage is developed across said impedance and is applied to said auxiliary electrode, said bias voltage being related to the number of cathode electrodes energized and exhibiting cathode glow and conducting current at each character position.

10. Multiple-position display device and system for operating the deivce, said device comprising a gasfilled envelope including a plurality of groups of cathode electrodes and an anode electrode associated with each said group, each such group of cathode electrodes and its anode electrode comprising a character position in said display device, corresponding cathodes of the different groups being interconnected by a single common conductor, there thus being a single common cathode conductor for each cathode electrode in each of said groups, and an auxiliary electrode in operative relation with all of said groups of cathode electrodes and their anode electrodes and including a portion disposed between each anode and the adjacent groups of cathodes and serving as a shield therebetween, said system comprising a separate anode driver circuit connected to each said anode electrode in said display device,

a sequencing circuit coupled to all of said anode drivers for turning each one on separately and in turn whereby each anode can be connected in circuit with a selected group of cathode electrodes,

a separate cathode driver circuit connected to each of said common cathode conductors, each such driver circuit thus being connected to the same corresponding cathode in each of said groups of cathodes,

a source of data signals coupled to said cathode driver circuits for energizing a selected group of cathodes as each cathode is connected in circuit;

a first current flow path from each of said anode drivers through separate resistive paths to all of said cathode drivers,

a second current flow path from each of said anode drivers through a resistive path to said auxiliary electrode, and

a third current flow path from each of said anode drivers to its anode and through said display device to its group of cathode electrodes.

l l l

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3509420 *May 2, 1968Apr 28, 1970Burroughs CorpDriver circuits for display devices with spurious glow eliminating circuit
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3938135 *Nov 27, 1974Feb 10, 1976Zenith Radio CorporationGas discharge display device and an improved cell therefor
US4201983 *Mar 2, 1978May 6, 1980Motorola, Inc.Addressing circuitry for a vertical scan dot matrix display apparatus
DE3410876A1 *Mar 22, 1984Oct 3, 1985Siemens AgCircuit arrangement for driving a gas-discharge display device
Classifications
U.S. Classification345/42, 313/517
International ClassificationH01J17/49
Cooperative ClassificationH01J17/491
European ClassificationH01J17/49B
Legal Events
DateCodeEventDescription
Nov 22, 1988ASAssignment
Owner name: UNISYS CORPORATION, PENNSYLVANIA
Free format text: MERGER;ASSIGNOR:BURROUGHS CORPORATION;REEL/FRAME:005012/0501
Effective date: 19880509
Jul 13, 1984ASAssignment
Owner name: BURROUGHS CORPORATION
Free format text: MERGER;ASSIGNORS:BURROUGHS CORPORATION A CORP OF MI (MERGED INTO);BURROUGHS DELAWARE INCORPORATEDA DE CORP. (CHANGED TO);REEL/FRAME:004312/0324
Effective date: 19840530