US2552761A - Number display arrangement - Google Patents

Description

May 15, 1951 G. T. BAKE R 2,552,761

NUMBER DISPLAY ARRANGEMENT 7 File May 25. 1947 I e Sheet s-Shee t 2 I raw x 703) vauz) 'wm) m0 INVENTOR GEORGE THOMAS BAKER ATTORNE Y May 15, '1951- v G. T. BAKER 2 552,761.

- NUMBER DISPLAY ARRANGEMENT Filed May 23, 1947 a Sheets-Sheet 4 INVENTOR GEORGE moms BAKER ATTORNEY 1951 G. -r. BAKER NUMBER DISPLAY ARRANGEMENT Filed May 23, 1947 6 Sheets-Sheet 5 INVENTOR GEORGE THOMAS BAKER ATTORNEY May 15, 1951 G. T. BAKER NUMBER DISPLAY ARRANGEMENT 6 Sheets-Sheet 6 Filed May 23, 1947 FIGURE GEN.- F

INVENTOR. GEORGE T. BAKER ATTORNEY Patented May 15, 1951 UNITED STATES TENT O FFKCE NUMBER. nrsrmv ARRANGEMENT company Application May 23', 1947, Serial No. 750,142 In Great Britain June 12, 1946 9' Claims.

The. present invention relates to display arrangements. and is more particularly concerned with arrangements. adapted to display: variable items. of information.

Display devices of this type find many applications. in the signalling art and the design of dis play devices suitable for the various applications has been a problem on which considerable time has been. spent without attaining a completely satisfactory solution. One particular application is. to number display systems used in automatic telephone systems. 0ne form of display at pres-- entin use consists of a bank of lamps arrangedbehind a. stencil. plate, the lamps being divided into, for example, four groups of ten lamps to provide a four-digit display. -Thestencil platehas characters so that the whole display occupies a width of approximately 15 inches. This. display is not entirely satisfactory since the exaggerated spread together with. the variable horizontal and vertical displacement renders the numbers comparatively dimcult toread. An other type of display such as used with totalisators employs a so-called monogrammic indicator in which the: characters are built up from small. elements but this is entirely unsuited for a small display. In: addition there are numerous mechanical solutions tothe problem using, for instance, number wheels, dial pointers and. so on but their chiefdrawback is the slowness of setting and further. they are often difficult to read, extravagant in space and are complicated in construction.

It: is one of the objectsof'the present invention to provide an arrangement which is compact and which provides a clear display of one or more of a. plurality of predetermined characters in any desired relationship.

According to one feature of the invention in aniarrangement. for displaying one or more characters on the screen of a cathode ray tube, the movement of the spot is controlled by a combination: of varying character-producing potentialsand steady spacing or layout potentials.

According to.a further feature of the invention man arrangement for displayinga plurality of characters on. the screen of a cathode ray tube, varying potentials are-used to trace the outline offeachof saidcharacters and steady potentials ofapDlOpriate value are used to locate each of I the. characters at any. desired position on the screen. Preferably electrostatic deflecting means areem-ployedfon' controlling the movement of the spotzand thecalternatingpotentialsare applied to the. deflection plates; It; will. however be understood that electromagnetic deflection may be used in which case the alternating potentials will be converted into alternaing currents for application to the deflecting coils.

According to another feature of the invention in an arrangement for causing the sustained display of a plurality of characters on the screen of a cathode ray tube, periodically varying potentials are used to cause the spot to traverse the outline of a character at a speed of repetition sufiicient tocause the appearance of a sustained display and steady potentials of appropriate value are used to locate each of the characters at any desired position on the screen. 1

Accordingtoa further feature of'the-i'nvention in an arrangement for displaying a plurality of characters on the screen of a cathode ray tube by successively applying to the tube a series of combinations of potentials, each combination consisting of periodically varying potentials to produce the appropriate character and directpotentials to provide the correctspatial relationship between successive characters. Preferably each individual character W-ill be repeated at l-iigh speed while the complete trace will also be repeated: rapidly as long asthe particular displayis required. Persistence of vision will cause the appearance of a steady display and it will beappreciated that the display will be improved-by the use of a cathode ray tube having anappreciable after-glow.

According to a further feature of the'invention in an arrangement for displaying anyoneor more of a plurality of predeterminedcharacterson thescreen of a cathode'ray tube, predetermined-char acters-are adapted tobedisplayed by means of'a generator arranged to produce periodically-vary ing potentials suitablefor tracing the outlineof each of said characters, selection-of one'or more of the potentials being controlled by external means to cause one or more selected characters to be displayed on the screen.

According to a further featureof the invention an arrangementf'or displaying oneormore'bf a plurality of predetermined characters onthe screen of acathode ray tube comprises means for generating periodically varying potentials" suitable for producing a plurality of predetermined characters; means for selecting one or more of said alternating potentials as determined-bythe required characters and means for rendering efiective said alternating potentials to, produce the-desired display.

According to a'furtlier feature of the invention an arrangement" for displaying any one=ormore of a plurality of predetermined characters on the screen of a cathode ray tube includes means for generating potentials suitable for causing the spot to trace each of said characters.

According to a further feature of the invention in an arrangement for generating control potentials suitable for causing any one or more of a plurality of predetermined characters to be displayed on the screen of a cathode ray tube, an alternating potential is applied to a plurality of impedances arranged to vary periodically in time to generate potentials suitable for producing said characters.

The invention has particular application to telephone systems in which information relating to a connection, for instance, the number of a calling and/or called subscriber or the duration of the call and so on, is transmitted to a central point where it is rendered available by a record or display.

'According therefore to a further feature of the invention, in a telephone system provided with equipment for rendering available information relating to a connection, the equipment includes a cathode ray tube for causing the display of individual characters on the screen, the selection of a plurality of characters to display the desired information being effected in accord ance with impulses transmitted to the equipment.

These and other features of the invention will be better understood from the following description of one method of carrying it into effect, reference being had to the accompanying drawings comprising Figs. 1 to 8. In the drawings:

Fig. 1 shows the layout of the main components,

Fig. 2 shows the circuit of the varying voltage or figure generator,

Fig. 3 shows the method of analysing a character,

Fig. 4 shows a scale employed in determining the shape of the rotating vanes,

Fig. 5 shows typical shapes of the vanes and Figs. 6 and 7 show two constructional views of the variable voltage generator.

. Fig. 8 shows, in circuit diagram form, the schematic layout of the system, along the lines of Fig. 1, but more in detail.

Referring first to Fig. 1, the equipment comprises four main components, first the cathode ray tube CRO which may be any of the standard units, preferably of the slow screen type, of a size determined by the display requirements. The second component is the layout control circuit LC which feeds the tube successively with the appropriate varying voltages or figure voltages over the leads OF to make up the display and superimposes the necessary steady potentials over the leads LP to locate each figure in the appropriate position in the frame or on the screen.

This equipment may consist of a uniselector as shown in the drawing together with a number of resistors and in many cases equipment already provided to serve other purposes may be used. The uniselector is shown as having two wipers, one for successively feeding the fixed or locating potentials and the other for successively feeding the -X- and Y-varying voltages to the cathode ray tube. It will, of course, be understood that the drawing is purely diagrammatic and, in actual practice, the X- and Y-voltages would be fed over separate wipers of the uniselector as shown in Fig. 8.

The third component consists of the figure selector FS which, in actual practice would form part of the apparatus controlling the display.

Again this equipment may consist of a plurality of uniselectors as shown in Fig. 1 or 8 each of which feeds the appropriate X- and Y-voltages to the contact banks of the uniselector in the layout control circuit. If, for example, four characters are to be displayed, provision would have to be made for feeding four sets of X- and Y-voltages and four uniselectors would be necessary. These uniselectors would be set by means external to the equipment, for instance, by impulses transmitted thereto, the leads from the figure generator being multipled over the appropriate banks of the uniselectors. The arrangement shown in Fig. l is purely diagrammatic in that each uniselector is shown as feeding both X- and Y-voltages to the layout control circuit. Alternatively the figure selectors may consist of groups of relays which selectively connect the contacts of the layout selector to appropriate terminals of the figure generator.

Finally the fourth component consists of the figure generator FG which provides the alternating potentials for producing the trace corresponding to the integers, 1 to 0. One such unit will supply a large number of tubes and thus the system is particularly suited to providing a multiplicity of adjacent but otherwise independent displays.

The circuit of the figure generator is shown in Fig. 2. The oscillator functions at about 500 kc., and feeds the common rotor of the multiunit variable condenser shown as CZX, C2Y, C3X, C3Y and so on. Each fixed plate is connected through a load resistance RAZX, RAZY, RA3X, RA3Y and so on to earth. The high frequency potential developed across the resistance, is rectified by the appropriate one of the dry-plate rectifiers MRZX, MRZY, MR3X and MR3Y. The smoothing units RBZX and CA2X and so on are introduced to prevent the highfrequency blurring the output, which is normally situated in the lower audio frequency band.

Each figure with the exception of 1 requires two control potentials and there are thus nineteen plates and output terminals. The actual construction of the figure generator is shown in Fig. 6 from which it will be seen to consist of a pressed steel base it provided with bearing brackets H and I2-which are secured to the base H) by screws I3 and I l. The base [8 also carries a motor I5, secured to the base by screws [6, an oscillator IT shown in dotted outline and the various resistors and rectifiers [8 associated with the fixed capacitor blades and the capacitors l9 forming part of the smoothing circuits. The motor I5 serves to drive the shaft 20 which by means of the insulating coupling 2| is connected with the shaft 22. The shaft 22 is mounted in the brackets II and I2 by means of ball races 23 the latter being a push fit in phenol fibre insulating plates 24 suitably secured to the brackets by screws 32. The shaft 22 carries the condenser vanes iY to HY, corresponding pairs of which e. g. 2X and ZY, are primed to metallic bushes 25 secured to the shaft 22 by retaining screws 25. Intermediate metallic bushes 21 servev to separate each pair of vanes from adjacent pairs. The rotating condenser vanes co-operate with one pair of fixed plates or blades 28 each pair being spaced apart by metallic distance pieces 29 and secured to insulating blocks 30 by screws 3i. It will be noted that in Fig. 7, which is an end view of Fig. 6 from the top of the figure, the rotatable vanes are shown ascircular. This is merely for the convenience of drawing sincethe r e u a ha Q h va s s d in r ctice diificult tofs hiow on a drawing'of this nature. Electrical connections maybe made to thevane shaft 22'bymeanis of'abrush and slip ring arrangement (not'shown) -or by a spring-loaded ball engaging'witli the end of the shaft.

It will be understood that as the motor is con-' tinuou ly operating and the' output from the $i l t r app e 0 3 th a i g va 2 n er ar a e td aees"a 'a wa avai ble across the various load resistances. The desired varyingvoltages 'will be taken from the load re- Sis'tanc'e's according to the setting'of the figure selector. and will be applied in succession to the cathode ray tube by the rotation of the. wipers of the layout control uniselector. The time during which the wipers of the latter uniselector re main on a bank contact greater. than the: time Thus giving the capacity required from the a: and y capacitors for any position of the shaft. These two polar curves can be obtained directly I from Fig. 3 and, if the fixed blades were of of 'ro tat ion'of "the vane shaft 22" so that charaoter may. be traced a number of times be} fore passing onto the'nextf If'thehumber qf characters to be displayed is predetermined for example, four, the first four contacts of the layoutcontrol uniselector may be, multipled through the bank and the complete'trace will be continuously repeated as long as the uniselector continues to step'. i In some cases it may be sufficient toftrae'e each character once, the determining 7 factor being the afterglow characteris tics of 'the' screen. w t

It will be seen that the output potential of the negligible. Width, they would represent the desired ro or sh pe.

In practice, it is necessary to make the fixed plates as wide as possible and an 18 deg. segment has. been found convenient. Before Equations 6 and. 7 can represent overlapping areas of the ca;

pacitor vanes, two corrections are necessary.

Firstly due'tov the wedge, shape of the fixed vanes the. radial scale must be adjusted so that the divisions on the scale represent equal increments of overlapping area. 'Referring'to Fig. l this is effected by first selecting suitable radii R0 and R1 for the circles Bo and B10 when the figure generator depends on'the instantaneous capacity of the: rotating condenser and if the vanes are, correctly Shaped almost any desired output can be achieved. The general principles for shaping thevanes will nowj be described.

Consider the reproduction of an outline, as for example, the 2 shown in Fig. 3. Imaginary axes a be d a n fi t sh h -r stin e ition of h spot, one parallel to the deflection produced by the X plates the other parallel to the Y plate deflection. On a cathode ray tube the deflections are substantially proportional to the applied po: tentials', so that the distances, from these axes re. the. :c and y coordinatesjrepresent the re,- quired 'defiection potentials. Theoutl ine shown istherefore a relationship between and y ofthe m. a

This curve is traced out by the movement of the spot and therefore the relationship is more. accurately expressed in terms of; a parameter t,

y=f 2(t) (3) The traverse is repeated many-times hence these. represent periodic functions. The load resistance (RA2X and so on, Fig. 2) is kept relatively smalland'the output potentials are therefore roughly proportional to the instantaneous capacity of the variable condensers.- Therefore Equations 2 and 3 can be written.

which represents a timeunit. In practice, it has radius of the circle B1 is given by R. =Ro 1zm R0 I the square of the distance from the origin,

see ndly, the pe me e Qf t e o tin va e does not-cut the fixed blades in an arc of a circle, but in general, includes varying heights. actual area is represented by an integral takenbetween two radii, 18 deg. apart. Fortunately the sinefunctions and straight lines which compose the main part of the, figures integrate into sine functions and straight lines respectively, and therefore thiseffect does not entail a great deal of modification, except at discontinuities. One or more of these occur inmost figures and the reversals. at either end of the traverse provides further examples. A theoretically perfect solution cannot be obtained, but the shape of the figures are not critical and approximations can be obtained, which give a divergence from the ideal almost unnoticeable on the trace.

of equal divisions, and, make. a polar plot on the scale shown in Fig. 4., where the semi-circle is divided up into as many. segments as there are trace divisions, (the remainder of the circle is used. for the reverse traverse). Correct for dis.- continuities by approximate means and generally smooth thefinal result to give a smooth rounded figure. Typical outlines achieved by the above bbed-. ar Shown n A further correction canbe introduced to al- .1? er. he a tha he a ue, of he oad e- The 7 sis'tanceis not negligible, since electrical efficiency requires this to be fairly high in comparison with the capacitor impedance. The efiect, however is to give a slight flattening at the upper end of the figure and it is fairly simple to allow for this when drawing the original outline. is

The required outlines should be drawn several times fullsize; They can then be clipped onto a phenol-fibre board and the outline carefully pricked through to the board. When the paper is removed the marks may be joined up with a scriber into a smooth continuous groove, which can be used as a master on a pantograph engraving machine to inscribe the profile at the correct size upon a steel sheet. When this is cut out and case-hardened, it may be used as a template to produce any number of the required vanes which are formed in aluminum or similar metal or alloy. It will be seen that the invention provides an extremely compact and flexible form of display arrangement and while the description of the preferred embodiment refers to the display of figures, it will be understood that other characters may be displayed either alone or in combination with figures. It will also be understood that arrangements other than those described above may be employed for applying the variable and steady voltages to the cathode ray tube.

The applications of the display arrangement are many and will be obvious to those skilled in the signalling art. Reference has already been made to its application to automatic telephone systems either for displaying a called number or for displaying a calling number in systems employing line identification equipment. The impulses or other signals representing such numbers would be transmitted to the equipment and would control, preferably directly, the switching mechanism of the figure selector. In telephone systems employing equipment for automatically determining particulars of connections, the arrangement of the present invention may be employed in place of a recorder or printer by providing equipment for photographing each display, so that a permanent record is obtained of each display which in this case will consist of the particulars of a connection. It will be understood that other methods of controlling the figure selector than that shown diagrammatically in Fig. 8 are possible, and that under certain conditions all of the FS uniselectors could be set simultaneously from markings, rather than successively, from dialled impulses.

I claim:

1. In a character outline display system utilizing a cathod ray tube, a generator for producing a steady alternating voltage wave of a single frequency, a plurality of variable impedances connected to said generator each having a rotatable element, said rotatable elements all having different configurations corresponding respectively to the outlines of the diiferent characters available for display, means for simultaneously rotating said rotatable elements to cause said impedances to convert said steady alternating voltage into a plurality of varying voltages corresponding respectively to said different character outlines, remote control means for selecting certain of said varying voltages, and automatic means for successively and repeatedly applying said selected voltages to said tube to cause the outlines of the corresponding characters to be traced and to be displayed side by side simultaneously by said tube.

2. Ina chara putline-display system in--'- 8 eluding a cathoderay tube, a cyclically operating generator for producing a uniform alternative voltage Wave, a plurality of variable condensers connected to said generator each having a rotatable plate and afixed plate, all of saidrotatable plates provided respectively with different configurations corresponding to the outlinesof the difierent characters to be used, a shaft for repeatedly rotating said rotatable plates to cause said rotatable and fixed plates to convert said uniform alternating voltage into a plurality of varying alternating voltages corresponding respectively to said plate configurations, means for converting said'varying alternating voltages to correspondingly varying unidirectional voltages, remote control means for selecting one or more of said varying unidirectional voltages at will, and cyclically operating means for successively impressing said selected voltages on said tube at regularly repeated intervals to cause said tube to display the outlines of the corresponding characters simultaneously in laterally spaced apart relationship. I r

3. A display system as in claim 2, in which the configurationsof said rotatable plates are such as to cause said tube to trace the outline of each of the displayed characters first in one direction and then in the other, as long as the correspohdlng varyingunidirectional voltages are im-' pressed on said tube.

4. A display system as in claim 2, in which the configurations of each of said rotatable plates are such as to cause said tube to trace the outline of each of the displayed characters once in each di- 7 rection for each rotation of said shaft during the times the corresponding varying voltages produced from such plate are connected to said tube. Y

5. A display system as in claim 2, in which two condensers are normally employed for each of said difierent characters, to separately and simultaneously control the abscissa and ordinate values with respect to common base lines for each of said character outlines containing such values.

6. In a display system for displaying a plurality of characters simultaneously in outline on the. screen of anoscillog'raph, a generator common to said system for producing a steady alternating current of a single frequency, a plurality of variable condensers ccnnected to said generator, a metallic plate for each said condenser each hav-- ing a different peripheral configuration corresponding respectively to the abscissa and ordinate outlines of each one of the diiferent character outlines utilized in the system, said respective outlines traced alternately in opposite directions on each plate, means for rotating said plates in unison to cause said condensers to change said steady alternating current into a plurality of varying alternating currents corresponding to said peripheral configurations, means for automatically translating said. varying alternating currents into correspondingly varying unidirectional potentials, a first switching means for directively selecting a plurality of said last varying potentials, and a second switching means cyclically operated for successively applying said selected potentials to said oscillograph to cause the corresponding character outlines to be displayed simultaneously on said screen.

tothe maximum number of characters to-be dis played on saidscreen-at-one time -and plural--- channels in said second switching means for applying one of said plurality of steady potentials to said oscillograph with each of said selected varying potentials to cause said displayed character outlines to be maintained in a definite spaced relationship with one another on said screen.

8. In a number display system for displaying plural digit numbers on the screen of a cathode ray tube, a generator common to said system for producing a uniform alternating voltage, a group of impedances connected to said generator, a metallic plate for each said impedance each having a different peripheral configuration corresponding respectively to the instantaneous abscissa and ordinate values constituting the out- -lines of the various numeral characters employed,

means for rotating said plates in unison to cause said impedances to convert said uniform alternating voltage into a plurality of varying alternating voltages corresponding to said peripheral configurations, rectifier means for converting said varying alternating voltages into correspondingly varying unidirectional voltages, a plurality of steady unidirectional layout voltages of difierent magnitudes, a first switching means directively operable to select one or more of said varying unidirectional voltages, and a second switching means automatically operable to successively and repeatedly apply said selected 10 varying voltages and said layout voltages to said tube to cause said tube to display the number corresponding to said selected varying potentials by tracing the outlines of the selected characters successively in opposite directions side by side on said screen.

9. A number display system as in claim 8, in which said first switching means comprises a plurality of multi-contact stepping switches individually settable in response to received impulses, and in which said second switching means comprises a unidirectional stepping switch having three contact levels, with said plurality of switches connected respectively to successive contacts in two of said levels, and said layout potentials connected respectively to corresponding successive contacts in the other of said levels.

GEORGE THOMAS BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,639,000 Horton Aug. 16, 1927 2,281,350 Bryce Apr. 28, 1942 2,363,416 Henroteau Nov. 21, 1944 2,378,383 Arndt June 19, 1945 2,421,747 Engelhardt June 10, 1947

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