US1479370A - Electric arc lamp - Google Patents

Description

' Jan. 1, 1924 1,479,370

, L. R. COFFIN ET AL ELECTRI C ARC LAMP Filed June 8. 1917 3 Sheets-Sheet 1 Figi . 1N VEN ToRs f awr Jan. l y

1,479,`3 70 l.. R. coFFlN ET AL. K

ELECTRIC ARC LAMP Filed June 8, 1917 3 SheetsSheet 2 N @EN TORS w Q91,"

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l such as are especially adapta le for use inA which will o erate successfully with the useA harina Jui. 1, i924.

' UNITED s'rATEs LESLIE n..I corm, or Eminem, wAsHINc'i'oN,4 im nEUnEN w. ins'ncx, n.,

i 1,419,310 PATENT oFEicE. i

0F SAN FRANCISCO, CALIFORNIA.

ELECTRIC ABC2v LAMP.

Application led June 8,

State of Washington, and REUBEN. W. MAs- Tron, Jr., a citizen of the United States, and

' a resident of San Francisco, in the county of San Franciscoand State of California, have invented certain new and useful Improvements in Electric Arc Lamps; and we do hereby declare the .followin to be a f ull, clear, and exact descri tion o the invention, such as will enable ot ers skilled in the art to which it appertains to make and use the same.

, This invention vrelates to improvements in electric arc lamps and more articularly to c inematographic, stereopticon or other pro- "jecting purposes.

One object of the presentinvention is to provide a projector type of electric arc lamp of a single-p ase alternating current of commercial fr uency without necessity for the use of auxi iary rectifying a paratus, and which 'may also be successi ly and accurately operated with the use of unidirectional electric currents.

A further object is to provide, in an arc lamp of the ty specified, simple and efficient means w ere y' the three electrodes employed, may be quickly and accurately adjusted with relation to each other and. relatively to the projector lens.

A further object is to so arrange the elec trodes and circuits of an electric arc lamp as to facilitate such rectification of the current employed as can obtain incident to theaction of the arcs at the cooperating electrode terminals.

With these and other objectsin view, the invention consists in certain novel features of construction and combinations of parts and circuits as hereinafter set forth and pointed out in the claims. I y

In the accompanying drawings; Figure 1 is a diagrammatical view showing 'the arrangement of electrodes and circuits when the lamp is employed withA unidirectional currents; Figure 2 is a diagrammatical view showing the adaptation of the lamp for sin;

gle-phase alternating currents; Fi res 3 and 4 are views, partly in elevation an partly in section, of a lamp embodying the invention;

1917. Serial I0. 178,588.

Figure 5 is a fragmentary sectional view showing the hinge connection between the rents, an arrangement of three electrodes is provided so as to obtain a plurality of arcs, two of said electrodes being connected reslpectively vby leads to the end terminalsof t e secondary winding of a single-phase alternatin current supply transformer, and

the-thir to the neutral or mid-point of said secondary windnv of the single-phase su ply transformer. eactance coils of suitable constants may be laced in circuit with the leads connecting t e three electrodes of the lamp to the secondary winding of the singlephase supply transformer, for the urpose of. regulating and maintaining the p uralty of arcs between said-electrodes..

' In the alternating current operation of the lamp, partial rectification of the alter.

nating current supplied takes` lace. Hence the arcs produced in the three e ectrod'e lamp with alternating current areboth unidirectional and alternating in character. When a proper overlapping of the successive half waves of current be produced, the rectifying action which obtains exerts a steadying influence on the plurality of arcs between the lcooperating electrodes.

The three electrodes are so arranged as to converge toward a common oint and in addition to separate 'means ofp adjustment for the electrodes individually, a pantog'raphic structure is employed to obtain a simultaneous movement of the three electrodes toward the common oint of convergence by the manipulation o one controllin rod. The advantage of an organization o this sort lies in the fact that the arc is always maintained at a sensibly constant distance .from the projector lens. This will be readily understood when consideration is gilven to the fact that as the arcsburn and t e yelectrodes wear away, thus increasing both the distance from .the arcs to the projector lens and the arc-gaps between electrodes, a slight adjustment of the pantographic control r'eadjusts the arc separation between electrodes, and hence immediately restores the arc to its original position with respect tothe projector lens.

Referring to Figure 1, 1, three carbon electrodes, the former of which are connected respectively through two resistances 4, 5 toa common point 7, which is the negative terminal of the direct current supply circuit. The third or central carbon 3 is connected with the positive terminal 6 of the direct current supply circuit. The three electrode arrangement results in the plurality of arcs being localized and forming a very hot" crater at the positive electrode 3, givlng a greater.. luminous intensity than is obtainable With the ordinary/two electrode type of arc-lamp. In addition, the arc is rendered very steady and requires little attention or adjustment, a feature of much importance in cinematograph apparatus.

In Fi re 2, 1, carbon e ectrodes, connected through respectively, to points 2, 3 represent the three two reactance coils 4,'5 8, 9, representing the outer ends of the secondary winding of av single-phase alternating current 'supply transformer 9. The third carbon electrode 3 is connected through a reactance coil 6* to the mid-point 7*? of the secondary winding 8, 9 of the single-phase alternating current supply transformer. When thev singlephase alternating current supply transformerjis remote to the lamp, the neutral point 7 of the single-phase circuit may be obtained by. providing two balanced react-- ances disposed in series and bridged across the circuit at a point corresponding to 8,A 9. The reactance coils 4, 5 are inserted to provide an overlappin of successive half-waves of current essentia to the continued excitation of the arc. The characteristics of these reactance coils are not. specifically given, since they are determined by the requiredv angle of overlap of the currents of successive half Waves necessary to give the desired stability together with. other factors which will vary w1th the capacity and usage of the lamp. Reactance coil 6 of required characteristics is inserted in circuit between the points 3 and 7a to maintain the voltage in said circuit above the counter E. M. F. of the arcs. With this arrangement, the alternatin current supplied is 1n part rectified and t e arcs are formed solely by successive half vwaves of current, between electrodes 1., 3 and 2, 3 respectively are unidirectional.

The arcs occurring from electrodes 1 by 3 to 2 and 2 by 3 to 1 are alternating in charvided circuits indicated by 3, 6

2, 3 represent rieddby the former of which are acter. The rectified part of the alternating current supplied,-therefore, exists in the diand 7./ Owing to the high temperature of the carbon-arc and its consequent low voltage range of rectification, a complete rectification of' the alternating current cannot4 take place such as would be possible with electrodes of lower temperature boiling points.

Electrode 3 is smaller than either electrodes 1 or 2 which fact` promotes high incandescence of said electrode d'ue to the passage of the arcs from 1 by 3 to 2 and from 2 y 3 to 1 in the case of alternating components of the arc current and from 1 to 3 and 2 to'3 respectively in the'case of the unidirectional component of the arc current. In the lamp shown in Figure 3, electrodes 1 and 2 are supported respectively by holders 4b and 5" carried by arms 6b and 7 b, the lutter being supported by the carriers 8'J and Jb Iwhich are in turn supported by the pantographic structure 10,11, 12 and 13. The electrode 3 is sup A arm 15, w ich is supported in the carrier 16, the latter being pivoted on the pantograph arms 12 and 13. In addition to being pivoted on the pantograph arms 12 and 13, the carrier 16 slides in a slot on the base 17. The two-arms 10 and 11 of the pantograph are pivoted to a block .18 which orted byvholder 14 caralso slides in vla slot on the base 17 The block 18 is driven by the threaded I'Od 19. swiveled in a block 2() rigidly attached to the base 17 The upper and lower junctions of thepantogjraph arms 10, 12 and 11, 13 are pivoted y axles 21 and 22 passing through each pair and a slot 21b in the carriers 8* an 9b respectively and thence extending into the slotted upright guides 21 and 22'L (see Figures 3 and 4). Thus-lateral v movement of the upper and lower pantograph arm junctions is restrained, and hence operation of the rod 19-causes a recession or approach of the carriers 8b and 9", and therefore, also, of the electrodes 1 and 2. By reason of the pantograph arms 12 and 13 being pivoted to the carrier 16 which is guided Aon the base 17, va recession or approa h of the'carrier 16 is caused and therefore,

also of the electrode 3. v Thus operation of the rod 19 causes contemporaneously and associated carriers, arms,.holders, etc.,

above described, is rigidly attached to a shaft 23 movable vertically in a' holder by means of a rack and pinion gearing 25-26 controlled by a manually operable rod 27. The holder 24 is arranged to slide on two parallel rods 28, 29 usually provided in the lamp cabinet associated wlth commercial cinematographic machines.

Theelectrode holders 4", 5b and 14 are in- J able rod 41,

yby means of the bevel 7l* and 32 resulated from their carrying arms 6", 15 by the insulatedjoints 30, 3l and spectivel'y, and in addition, pivot joints' 33, 34 and 35 are provided between said insulated joints and the electrode holders 4", 5" and 14 by which means additional an lar adjustments of the three electrodes wit respect to one another can be made, if desired. he upper carrier 8b is made of two parts, the lower part being attached to the pantographic structure 10, 11, 12 and 13 in the manner previously described. The upperpart is hollow so that the arm 6b which supports the electrode holder 4b be caused to move axially forward or bac independently of the carrier 8h as operated by rod 19, by rotation of a threaded rod 36 swiveled in the u per part of the carrier 8b and entering a t readed socket in the arm 6". Moreover the upper part of the carrier 8* is hinged at or near one end to the lower by a pivot pin w andA part of said carrier 8b ar and screw jack arrangement, 37, zd by the manually opera le rod 38, can be caused to tilt up or down at one end, thereby raising or lower` ing the arm 6h and, therefore, also the electrode 1. Rigidly attached to the arm 6 is a spur gear 39 which meshes with another spur gear 40 attached rigidlyto a manually operresting in bearings attached to the upper. art of the carrier 8b, which can cause a ra ial movement of the arm 6b with respect to its axis, and hence also cause a radial movement of the electrode 1. l A collar 42 is provided on the spur gear 39 which fits about the spur gear 40 so that the two gears remain meshed regardless of the position axially, of the arm 6" controlled by the rod 36. l

The lower carrier 9" piece attached is constructed in one 10, 11 12 and 13 as previously described, and is hollow so that the arm' 7b which supports the electrode holder 5b and electrode 2 may be caused to move axially forward or back independently of the carrier as operated by rod 19, by rotation of the threaded rod 43 swiveled in the carrier 9" and entering a threaded socket -in the arm 7.

The central carrier 16 the arm 15 which supports the electrode holder 14 and electrode 3 may be caused to move axially forward or back independently of the carrier 16, 'asoperated by rod 19, by rotation ofthe threaded rod 44 swiveled 1n thesaid carrier 16 and enterinv a threaded socket in the arm 15. The threa ed rod 44 in this case sses through and is supported by the threadgd rod 19.

The lamp and its electrodes will in all cases be adjustable with respect to the lens of the projecting apparatus, said lens bein shown diagrammatlcally in Figure 3 and 45.

and` electrode 1 mayI to the pantographic structure is hollow so that` While we have particularly described and illustrated the best embodiments of our invention which are now known to us, it will be readily understood that many changes can be made in the form of our invention without departin from its spirit.

aving` fu y described our invention what we claim as new and desire to secure by Letters Patent, is

1. .In a projector type of arc-lamp,

electrodes axially towardl and away from the j lens.

2. An arc-lam for cinematographic, stereopticonv or ot er projection purposes comprising a panto raphic structure as a supporting means, t ree electrode carriers swun thereon, one being intermediate of the ot er two and slidin 1n a fixed support, electrodes mounted in said carriers, the outer electrodes converging toward the central electrode whereb a plurality ofarcs may be formed simu taneously, guides controllingthe direction of movement of the members of the pantographic structure and means for controlling the movement of the pantographic structure, electrode carriers, and therefore, also the three electrodes simultaneously, so that the latter will converge towar outer electrodes with two ter- LESLIE R. COFFIN. REUBEN W. MASTICK, JR.

Witnesses to signature of Leslie R. Collin:

N Noms, C. W. HOWARD. Witnesses to the signature of Reuben W.

astick, `r.: y R. T. lfoams, Gnonon W. SENGER,

s'ource of single phase alternat-

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