US2341431A - Lamp socket - Google Patents

Description

Feb. 8, 1944. H. N. FAIRBANKS LAMP SOCKET Filed June 22, 1942' INVENTOR @W A TTORNEYS Patented ch. 8, 1944 LAMP socxn'r Henry N. Fairbanks, Rochester, N. Y., assignor'to Eastman Kodak Company,

Rochester, N. Y., a

. corporation of New Jersey Application June 22, 1942, Serial No. 441.9147 8 Claims. (CI. 88-24) The present invention relates to lamp sockets of the type wherein a lamp is adapted to be inserted thereinto by a straight thrust as distinguished from screw sockets, and particularly to the combination of such a socket with a picture projecting apparatus.

As is well known, it is common practice to provide sockets for electric lamps into which the lamp is inserted by a straight thrust and then given a partial turn to lock it in place therein. These sockets are commonly referred to as bayonet type sockets and are adapted to receive lamps having a complementary bayonet type base. contact in the center of the base thereof adapted to engage the central contact in the base of the lamp, and the resiliency oi this contact in the socket opposes the insertion of the lamp into the socket. This contact in the socket is made resilient for two reasons. First, it forms an important part of thebayonet type lock in that it acts to hold the parts in looking relationship after the lamp has been partially rotated to establish the relationship. Secondly,- it insures a good electrical contact between the socket contact and the contact in the base of the lamp.

When lamp sockets of this type are used on apparatus which is subject to vibration and Jars it has been found imperative to place a strong spring behind the contact in the lamp socket in order to prevent the lamp from jarring from a locked relationship in the socket, to hold the lamp against any vibration, and to insure a good contact between the. socket contact and the lamp contact at all times. The strength of the spring necessary behind the base contact of a socket of the type set forth will vary with the particular application of the socket. v

In order to insert a lamp into a socket of the type in question it is necessary to thrust the same into the socketagainst the opposition of the spring contact by grasping the glass globe of the same. In cases where strong springs have been required in sockets it has been found that the force required to place the lamp in the socket has been sumcient to break the glass globe of the lamp. As a result. a lamp which might be expensive is wasted and there is a verygood chance that the person's hand is cut in the operation. Even if the thrust required in inserting a lamp into such a socket is not in fact suihcient to break the lamp globe, it is often suiilcient to make a person wary of changing a lamp in the socket for fear it will break. In addition, when one is compelled to firmly grip a Sockets oi.this type include .a resilient hot lamp, probably burned out, in order to remove it from its socket he is liable to get a painful burn. It is also significant that lamp sockets oi the type in question are very often mounted in rather inaccessible places so that in order to insert a lamp therein the lamp globe must be gripped at the extreme end by the tips of the fingers only withv the result that the thrust necessary to insert the lamp into the socket must be transmitted throughout the entire length of the lamp globe.

Therefore, the primary object of the present invention is the provision of a lamp'socket into which'a lamp is adapted to be inserted by a straight thrust in opposition to a resilient contact in the base of the socket after which it is adapted to be locked in said socket by the engagement of cooperating parts on the lamp base and socket shell and means for purposely decreasing the resilient force of said contact prior to changing a lamp in the-socket and again increasing the resilient force of said contact after the lamp is changed and'is ready for use.

Another object is the provision of a socket of the type set forth which is movable between two positions, a lamp changing position and a proiecting position, and including means for automaticalLv decreasing and increasing the resilient force of the socket contact as the socket is moved to and from said lamp changing position, respectively.

A further object is the provision of a socket of the type set forth wherein the circuit to the socket is automatically broken when the same is moved to said lamp changing position and automatically completed when returned to the projection position so that a person ha alamp is not startled by lighting up of a lam during its insertion into the socket.

Andyet another object of the present invention is the provision of a-socket of the type set forth which includes a contact having suflicient resiliency to initially locate a lamp in the socket and permit easy insertion of the lamp thereinto, and the resiliency of which contact is augmented by the resiliency of asecond contact when the socket is moved to its projecting po ition.

Another object is to have the socket mounted on a lamp house door of a picture projector so that opening and closing of, the door moves the socket between its lamp changing and projecting positions, respectively.- i v The novel features that I consider characteristic of my invention are set forth with particu- 2 s,s41,4s1 larity in the appended claims. The invention socket for the projection lamp It is one oi-the itself, however, both as to its organization and bayonet type and into which the lamp is adapted its methods of operation, together with addito be inserted by a straight thrust and alter tlonai objects and advantages thereof, will best which the lamp is given a partial turn 'to lock be understood from the following description oi 5 the same in the socket. As shown, the lamp specificembodim ts hen readinconnection socketmaycompriseacylinderll-ofanysuitwith the A drawing in which. able insulating material, such as porcelain, hard .Fig. 1 is a side elevational view, on reduced rubber, etc., having a circular recess ll into scale, of a well known type motion picture appa which the base of a lamp is adapted to be'inratus in combination with the lamp'house of i0 serted. The circular recess I! is lined with whichthesocket constituting'the present inven-- metal shell I. the upper ends of which are 'tion hasbeen shownfor the purpose of illustrat- 4 formed in'theshape 0! a u as indicated at in: one application oi the same, to term a partgoi a bayonet lock. Looking at Fig. 2 is an enlarged partial sectional view. of Fig. 4 it will be noticed that the inturned edge the lamp house of the proiectorshown in Fig. 1, it of the shell II is provided with two diametrically showing how a socket constructed in accordance opposed arcuate slots 2|. These slots are comwith one embodiment oi the present invention plementary in shape to two diametrically opmight be mounted on' the lamp house door, and posed wings 22 on the lamp base 23 so that when showing the lamp house door closed, the wings on the lamp base are lined up with F18- 3 i B Vi w Si r t Fis- 2 u showin '20 the arcuate slots the lamp base may be inserted the lamp house door opened and the socket into the socket after which apartial turn of moved therewith to a lamp changing position, the lamp relative to the socket will prevent the P18. 4 is a plan View "of the lamp socket with lamp ircm being pulled from the socket.

the lamp removed and showing the manner of slidably extending through a bore II in the mounting it on the lamp h u 1. and 25 bottom oi the socket is a contact 2! including Fig.; 5 is a top plan view oi the live resilient a cap 21 located in the socket recess and a stem contact mounted on the-base of the lamp house. at extending beyond the base of the socket and reference characters refer to correspondbeing slidably guided by a sleeve bearing ll fixed par throu hout the drawing. in the base of the socket. The contact 28 is nor- Generally. he present invention comprises a so mally forced into the socket recess by a coiled lamp socket into which a lamp is adapted to be spring II encircling the stem is of the contact inserted by a straight thrust against the oppoand being held under compression between the sition of a resilient contact after which it is cap of the plunger. and a fixed part of the socket. locked in said socket by the combined coopera-- as clearly shown in Figs. 2 and 3.

t on of ensasins pa on t e so s e a 85 Itwillbereadilyappreciated thatwhenalamp lamp base and theresilie'nt force oi the contact. is inserted mum e the t me 1| The structure is such that the resilient force 0! 1 th as thereof contacts th cap 21 of the the contact my be urposely reduced to a minicontact 2! and that the spring so op oses its mum to facilitate changing a lamp on the so ket insertion into the socket. This spring, however, and may thereafter be urposely increased to 4 is comparatively light, being of only sufiicimt firmly o he la p i t soc t dur s strength to initially hold the lamp in looking lection. The structure is so arran ed that h n relation with the socket, and does not alter the the resilient 'iorce oi the-socket contact is reopposition to the insertion of the lamp-which duced 'the circuit to the socket is autom ica known resilient contacts do which are relied upon broken.'and' when the resilient force is ag in 45 to exert the full force required to finally position increased the circuit to the so is 8 a lamp in its socket under operating conditions.

pleted: v A stop pin 32 extending radially through'the librypurp m of discloms the op r i and end of the stem It prevents the contact 2| irom otasocketconstructedinaccordbeinspropelledfromthesocketbythespringa ance'with the present'invention I have chosen when a lamp is removed from the socket.

to show the same in' com in t n with a The socket may be attached to the inside of the known type of motion picture .appmt B lamp house door il in any manner to move heever, it will be readily appre ilt b! n sk e tween two positions when the door-is open d and in the art that the socket oi the present invenclosed. To facilitate a final focusing of the lamp tion is not limited to the specific application relative to the picture strip moving through the ber of diiferent apparatus. bracket includin spaced cars 84 piv- Referring nowto the drawing, the motion D16", otedto lugs "on thelamp house door Ascrcw tureproiectorshowninl'ig.1isoneofaw fliimedtotheiamphousedoorextendsthmh Thelamphouseenclosesaprojectionlampthe iectlon apertureacrosswhichthefilmpa-eeraysofwhichpassthroughthefilmuitmssnis Gravitymaybereliedupontoholdtheupstandthefilmgateandtoandthroughaproiection ingarini'lotthebracketagainsttheadimtinl lenslttoasuitablescreen. showmoneside nutaorasprinmnotshowmmaybemoimted wallofthelamphouseilispivotedtothebotatthepivotpomtcisaidbrackettomrmally tomottfielamphouse,asshownatit,rlgs.2 pivotitinaclockwisedirectimiookingatrlea.

andstoiormadoorllwhichcanbeopened 1o2and3.

44, mounted on a locating stud 45 in the bottom wall of the lamp house, i held under compression between the underside of the free end of said contact 4| and a shoulder on said stud. Looking at Fig. 3, when the lamp house door is opened to change a lamp in the socket the only dependent upon the resilient force of the contact tending to puslfthe lamp-from the socket.

spring tending to force the contact 26 into the It is believed that the novel features and advantages of the present socket construction will be readily apparent from the above description thereof. By way of summation, it will sumce to say that the present socket construction provides the necessary strong spring in the socket for holding the lamp firmly against movement due to vibrations or jars, and at the same time permits the force of the spring to be purposely released to facilitate the insertion of a 28 engages the free end of contact 4| and causes a retraction, or compression, of the spring 44. Thus, the force of the spring 44 augments that of the spring 30 and the lamp is firmly held on locking relationship and a good electrical contact between cap 2'l of contact 26 and the contact in the base of the lamp is insured.

It will be observed that the metal shell I9 01' the socket is adapted to be electrically to one side of a source of potential through a binding post 46 in contact therewith and a wire 4'l connected to said binding post. The contact 26 is insulated from the metal socket shell by circular shoulder 48 of insulating material forming a part of the socket, and in fact is dead whenever the lamp house door is open. The other side of the source of potential is connected to the contact 4| by a wire 49 and when the lamp house door is closed and the end of the stem 28 is brought into engagement with the contact 4| the circuit of the lamp socket is completed. Consequently, the contacts 26 and Min eflfect constitute a-switch for the circuit to the socket, and which switch is automatically opened and closed when the lamp house door is opened and closed, respectively; or stating it more broadly, a switch which is autm ,matically opened and closed when the lamp socket is moved to and from its lamp changing position, respectively. It will'thus be apparent that when a lamp is inserted into the socket the same will not light and startle the person performing the operation because the circuit to the socket is automatically broken when the socket is moved to its lamp changing position.

It is pointed out that the present invention is not limited to use with sockets and'lamps having bayonet type locking connections, but is useful and adapted for use with any socket into which 'a lamp is adapted to be inserted by,a straight thrust against the opposition of resilient contact the resilient force of which forms a part of, or effects the operation of a locking locking the lamp in the socket inserted thereunto by a straight and lamp combination which'would meet these requirements, but which does not include a bayonet type locking arrangement, is disclosed. in' pending U. S. patent application Serial No. 371,- 242, filed Dec. 23, 1940,-in the name of Joseph Mihalyi. In this socket and lamp combination referred to, a screw base lamp is adapted to be inserted into a socket by a straight thrust and in opposition to the resilience of a contact in the base of the socket. The lamp is locked in the socket when one end of a bellcrank pivoted in the side of the socket engages a thread'on the lamp base and the engagement of the two being after once being mechanism for being thrust thereinto, said means including a is decreased to lamp into the socket. The added feature of automatically breaking the circuit to the socket when the resilient force of the socket contact permit an easy insertion of a lamp into the socket and automatically closing .the circuit when the resilient force of the contact is again increased after insertion of the lamp presents advantages which will be readily apparent to one skilled in the art. While the disclosed socket arrangement is particularly adapted for use with motion picture apparatus as set forth it will be readily apparent that the basic features of the same would be useful in other applications and could be readily applied to other apparatus.

Although I have shown and described certain specific embodiments of my invention, I am,

fully aware that many modifications thereof are possible. My invention, therefore, is not to be limited to the precise details of construction shown and described but is intended to cover all modifications coming within the scope of the appended claims.

Having thus described my invention, what I claim is new and desire to secure by Letters Patent of the United Statesis:

1. In an apparatus of the type described the combination of a lamp socket into which a lamp is adapted to be inserted by a straight thrust, means for looking a lamp in said socket after member in said socket adapted to engage .a projecting portion on the base of the lamp after the same is fully inserted into the socket, a movable contact in the bottom of the socket against which the lamp base is adapted to abut, resilient means normally forcing said' contact into said socket and thereby to oppose insertion of a lamp into said socket and to oppose the removal of thrust. Asocket the cooperating parts of said socket and lamp base from looking relationship when once estab-- lished, and means for alternately decreasing and increasing'the strength of said resilient means to facilitate changing a lamp in said socket and to firmly lock the lamp in the socket after such a change, respectively. r

2. In an apparatus of the type described the combination of a lamp socket into which a lamp is. adapted to be inserted by a straight thrust, means for looking a lamp in said socket after being thrust thereinto, said means including a member in said socket adapted to engage-a projecting portion on the base of the lamp after the same is fully inserted into the socket, a movable contact in the bottom of thesocket against which the lamp base is adapted to abut, a plurality of resilient means adapted to normally force said contact into the socket and thereby oppose insertion of a lamp into said socket and to oppose the removal of the coopera in parts of said socket and lamp base from looking relationship when once established, and means for purposely rendering certain of said resilient means ineiIective to facilitate changin a lamp in said socket and for again rendering the same efiective -aitersuchachangetofirmlylockthelampin the socket. I

3. In an apparatus oi! the type described the combination or a lamp socket into which a lampthe-same has been fully inserted into the socket,

a resilient contact in the base or said socket adapted to oppose insertion of a lamp into said socket and to oppose the removal 01 the cooperating parts oi said socket and lamp base from locking relationship when once established, said contact including an end extending through the base of said socket, means for movably mounting said socket to move from a lamp chan ngposition to a projecting position, a second resilient contact locatedto be engaged and retracted by the extending end oi said contact whenj the socket is movedto its projecting position whereby it augments the resiliency 01' said first contact to firmly lock the'lamp in the socket, and cite disengaged by said contact when the socket is moved to its lamp changing position whereby only the resiliency oi the contact alone need be overcome in efiecting a change of lamp.

4. In an apparatus of thetype described the combination oi a lamp socket into which a lamp is adapted to be inserted by a straight thrust, means for locking a lamp in said socket after. being thrust thereinto, said means including a member in said socket adapted to engage a proi'ecting portion on the base 01' the lamp after the same has been fully inserted into the socket, a resilient contact in the base or said socket adapted to oppose insertion of a lamp into said socket and to oppose the removal of the-cooperating parts of said socket and lamp base from lockin relationship when once established. said, contact including an end extending through the base of said socket. means for movably mounting said socket to move from a lamp changing position to a projecting position, a second resilient contact located to be engaged and retracted by the extending end or said first contact when the socket is moved to its projecting position, where-. by it augments the resiliency of said first contorce oithefirsttofirmlyholdthelampinlocked relation in the socket. and adapted to be disengaged by said first contact when the door is open.

whereby only the resilient force oi the first contact need be overcome in the operation of changing a lamp in the socket.

6. In a picture projector the combination with a lamp house, a pivoted door on said lamp house for opening and closing the same, a bayonet type lamp socket mounted on said door to move therewith and adapted to receive a lamp having a complementary bayonet type base, a resilient contact in the base ot. said socket adapted to engage the base of the lamp and including an end extending through the base of the socket. a second resilient contact moilnted'on a fixed part of said lamp house in a position to be en aged and retracted bythe extending end oisaidfirstcontactwhen the door is closed, whereby the resilient iorce oi the second contact augments the tom of the first to firmly hold the lamp in locked relation lnthe socket,andadaptedtobedisengagedby said -first contact'when the door is open, whereby only the resilient force of the first contact need be overcome in the operation of changin a lamp in the socket, and means for automatically breaking and completing the circuit to said socket when the lamp house door is opened and closed, respectively.

I; Ina picture projector the combination with a lamp house, a pivoted door on said lamp house for opening and" closing the same, a bayonet type lamp socket mounted on said door to-move therewith and adapted to receive a lamp having a complementary bayonet type'base. means for,

electrically connecting the shell of said socket to one side'oi a source of potential, a resilient contactinthebaseoisaidsocketadaptedtoenlm the contact in-theiamp base, said contact being normally insulated from the source of potential and including anend extending through the base of the socket, a second resilient contact mounted onafixedpartotsaidiamphouseinapositicn to be engaged and retracted by'the extending end of said first contact when the door is closed,

. whereby the resilient force or the second contact tact to firmly lock the lamp in the socket, and to be disengaged by said contact when the socket is moved to its lamp changing Position whereby only the resiliency oi the contact alone need be overcome in efiecting a change or lamp, and i 7 means for automatically interrupting the circuit to said socket when the sameiis moved to its lamp chan i position, 'and for automatically completingsaid circuit whenthe socket isv-moved to its projecting position.

5. In a picture projector the combination with a lamp house,- a pivoted door on said lamp'house for opening and closing the same, a bayonet type lamp socket mounted on said door to move therewith and adapted to receive a lamp having a complementary bayonet type base, a resilient contact in the base of said socket adapted-teen age the base oi the lamp and including an end extending through the base of the socket, a second resilient contactflnounted on a fixed part 01'. said lamp house in a position to be engaged and retracted by the extending end of said first contact when the door is closed, whereby the resiliaugments the force of the first to firmly the lamp in locked relation in the socket adaptedtobedisengagedbysaidfirstcon when the door is open, whereby only the resilient iorce oitbefirstcontactneedbeovercome the operation of changing a lamp in said second contact being connected to the other side of the source of potential whereby said two contacts constitute a switch for the circuit to the lamp socket.

8. In a picture projector the combination with a lamp house, a pivoted door on said lamp house for opening and closing the same, a bayonet type lamp socket mounted on said door to move therer with and adapted to receive a lamp having a complementary-bayonet type base, means for out force or the second contact augments the" electrically connecting the shell oisaid socket to one side of a source of potentiaL'a' pl contact extending through the bottom or. socket and adapted to move into and out oi socket, said plunger contact including a within the socket adapted to engage the contact in the base of a lamp inserted into said socket and an end extending below the bottom of said socket, a compression spring situated be-- tween the head or said plunger contact and the base oi." the socket and normally forcing said contact into said socket, a second resilient contact mountedonafixedpartoisaidlemphcueein hold ,lllli tact a position to be engaged and retracted by the extending end of said plunger contact when the door is closed, whereby the resilient force of said second contact augments the force of said compression spring to firmly hold the lamp in locked relation in the socket, and adapted to be disengaged by said first contact when the door is opened, whereby only the force of said compression spring need be overcome in the operation of changing a lamp in the socket, said plunger contact 'normally insulated irom the source of potential, and said second contact connected to the other side of said source of potential whereby said two contacts constitute a switch for the circuit to the lamp socket. 1

- HENRY N. FAIRBANKS.

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