US 2751569 A
Description (OCR text may contain errors)
June 19, 1956 c. H, J. ANDERSON ET AL 2,751,569
LAMP HOLDER Filed April 17, 1952 Charles Henri Joseph Anderson Johannes Hendricus Frunciscus Van Werd AGE/VT I/VVENTORS LAMP HOLDER Charles Henri Joseph Anderson and Johannes Hendricus Franciscus van Werd, Eindhoyen, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application April 17, 1952, Serial No. 282,852
Claims priority, application Netherlands May 28, 1951 4 Claims. (Cl. 339-188) This invention relates to lamp holders of the bayonet type comprising two or more resilient bottom contacts.
It is common practice to shape the bottom contacts in the form of piston contacts, but it is also known to provide a base plate which consists of insulating material and which closes at the bottom the space of the holder intended for the cap of the lamp, said base plate having passed through it the bottom contacts which are secured in the plate. The contacts and the plate are resiliently urged in a direction opposite to that from which the lamp is introduced into its holder. Since the contacts are here secured in the plate, the movement of one contact is acted upon by that of another contact, so that the base plate may assume an inclined position and/or a faulty contact with the lamp may occur.
The object of the invention is to provide a construction of a lamp holder of the above-mentioned type in which a highly satisfactory contact is made and in which there is a greater freedom in the type of the springs for urging the contacts.
According to the invention a lamp holder of the bayonet type comprising two or more resilient bottom contacts, and a base plate which closes at the bottom the space of the holder intended for the cap of the lamp, the bottom contacts extending through the said base plate, characterized in that the base plate, which is movable in the direction of the axis of the lamp holder, comprises apertures through which the bottom contacts extend with a predetermined clearance, in such manner that the movement of the contacts is limited by the base plate and that of the base plate is limited by cams provided in the holder.
In one preferred embodiment, the base contacts are constituted by extremities of metallic strips which extend in a direction transverse to the axis of the holder. it may in this case be desirable that the said extremities should be urged by helical springs and that the strips themselves should be enclosed in the housing with clearance.
In order that the invention may be more clearly understood and readily carried into effect, it will now be described in greater detail with reference by way of example to the accompanying drawing.
Fig. l is a cross-sectional view of a lamp holder taken along the line II of Fig. 2 and of the cap of a lamp to be inserted into the holder.
Fig. 2 is a plan view of this holder.
The lamp holder is constituted by a housing 1, which is made from insulating material, for example moulded from synthetic resin. Ceramic material is also satisfactory. The housing has the shape of an elongated box, at the centre of which an envelope 2 is provided. The latter embraces a cylindrical space 3, into which the bayonet cap of the lamp is to be inserted. Cams 4 provided on the inner wall of the envelope co-operate with pins 6 provided on a bayonet cap of a lamp. The holder shown is intended for such a cap comprising three I nited States Patent Patented June 19, 1956 pins. They slide through slots 7 and are finally urged into cavities 8.
A base plate 10 is urged against the bottoms 9 of the cams 4 by means of contact strips 11, of which two are provided. The latter, in turn, are urged by means of two springs 12, which are supported on a closing plate 13, secured in the housing with the use of two flanged sleeves 14. The latter are hollow, so that screws may be passed through them for securing the lamp holder on a base. The metallic strips 11 are not required to be made from particularly resilient material, they are enclosed in the housing with some clearance and are thus not subject to bending stress.
The base plate 10 may move through a small distance in the direction of the axis XX of the holder.
The contact strips 11 have parts 15, which are bent upwards and which extend through two apertures 16 of the base plate. Said aperture embraces the parts 15 bent upwards, which constitute the bottom contacts of the holder, with such clearance that they can shift independently of one another. Consequently, when a lamp is introduced into the holder, the contact strips 11 may bend independently of one another if solder knots 17 which are provided on the bottom of the cap and of which one only is shown, are not of the same height.
The base plate 10 serves to ensure that the strips 11 are not pushed upwards excessively and furthermore that forces transverse to the longitudinal direction of the strips, which might occur due to torsion of the cap of the lamp or due to the bottom contacts 15 sliding oil the solder knots 17, are neutralized.
The contact strips are bent over, at one of their ends, at 18. Here they comprise an aperture through which extends a screw 19 which carries a nut 20. A conductor 21 may be clamped in position by tightening the screw 19. The latter and the nut 20 are enclosed in the housing 1, so that they can not accidentally be lost.
The two contact pieces 11 extend in the tangential direction with respect to the pitch circle, shown in dotted lines in Fig. 2, of the contacts 15 and this, as viewed from the centre M of this circle, both to the left. This has the following purpose. When the lamp is inserted into its holder, the contacts 15 will shift in accordance with the arc of a circle-of which the centre is located in the vicinity of the screw 19. The apertures of the base plate 10 will thus shift not only in the vertical direction, but also a little in the horizontal rotational direction. By the choice of the direction of the strips it enables this rotational shift to be in opposite direction to the tendency to rotate brought about by friction of the knots 17 upon the contacts 15 and thus a reduction of the forces acting upon strips 11 is brought about in an ad vantageous manner.
What we claim is:
l. A lamp holder for a bayonet type lamp comprising a housing; a sub-base plate in said housing, a movable relatively flat base plate having a plurality of apertures therein and being superposed and spaced from said subbase plate, said base plate forming the bottom of said lamp base enclosing space, a side wall in said holder being provided with an abutment, and at least two contacts, resilient means co-acting with said contacts whereby each of said contacts extends a limited distance through an aperture in said base plate thereby urging said base plate in a direction substantially transverse to the plane of said sub-base plate and against said abutment, and means for securing said sub-base plate to said housing.
2. A lamp holder as set forth in claim 1 wherein each of said contacts has an offset, integral metallic arm which 4 extends in a direction transverse to the axis of said holder.
3. A lamp holder as set forth in claim 1 wherein said contacts are located in the tangential direction with respect to the pitch circle of said contacts.
4. A lamp holder for a bayonet type lamp comprising relatively flat base plate having a plurality of apertures therein and being superposed and spaced from said subbase plate, said base plate forming the bottom of said lamp base enclosing space, a side wall in said holder stantially transverse to the plane of said sub-base plate and against said abutment.
References Cited in the file of this patent UNITED STATES PATENTS 1,602,221 Godley Oct. 5, 1926 2,127,675 Clements Aug. 23, 1938 2,357,311 Carlson Sept. 5, 1944 FOREIGN PATENTS 56,867 Netherlands Aug. 15, 1944 26,067 Great Britain -2 of 1898 373,168 Great Britain May 11, 1932 546,041 Great Britain June 24., 1942