US 5,345,140 AGranted

Electric lamp arrangement with reflector

AssigneeU.S. Philips Corporation

InventorPetrus A. J. Holten

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Abstract

An electric lamp arrangement includes a reflector (10) having first and second mirror walls (12 and 22), which in axial sections are curved according to circular arcs (13, 23), the centers of which lie in an area between lines (15, 16) enclosing angles .beta. and .gamma. with a plane P defining the largest diameter (d), and in an ellipse-shaped area Q, respectively. The reflector has a relatively small, light-emitting window (30) of at most 0.7 d, disposed opposite a lamp base (1). An electric light source (3) is disposed within the reflector (10) near plane P and an axis (11). The reflector (10) may be integral with a lamp vessel (5) to give a reflector lamp or a pressed-glass lamp. Alternatively, the light source may have an envelope and may be secured within the reflector to constitute a lamp-reflector unit. The reflector effectively shapes radiation emitted by the light source into a wide beam of high intensity. Embodiments provide an equal illumination of a large area by means of several light sources arranged beside each other. Other embodiments provide a homogeneous illumination of a relatively large area.

An electric lamp arrangement comprising:

a. a lamp cap (1) provided with contacts (2);
b. a rotationally symmetrical reflector (10) having an axis of symmetry (11) and a largest diameter (d) in a plane (P) transverse to the axis of symmetry, said reflector including:
(1) a first internally concave, mirroring wall portion (12) behind the plane (P) which in axial cross-sections at a first side of the axis (11) is curved substantially according to a circular arc (13) having a center of curvature (14) in front of the plane (P), which first wall portion is situated adjacent the lamp cap (1);
and
(2) a second internally concave, mirroring wall portion (22) in front of the plane (P) which in axial cross-sections at the first side of the axis (11) is substantially curved according to a circular arc (23) having a center of curvature (24) behind the plane (P) , at the other side of the axis;
c. a light-transmissive window (30) which is intersected by the axis (11);
and
d. an electric light source (3) arranged in the reflector (10) in the vicinity of the axis (11) and of the plane (P) and connected to current conductors (4) which extend to the contacts (2) of the lamp cap (1),
characterized in that:
the first mirroring wall portion (12) in every axial cross-section at the first side of the axis (11) is curved substantially according to a circular arc having its center of curvature (14) situated in a region which lies predominately at the other side of the axis and which is bounded by lines (15, 16) which enclose an angle .beta. and an angle .gamma. of 23.degree. and 39.degree., respectively, with the plane (P) and which intersect the plane (P) in the point (17) where the first mirroring wall portion (12) intersects the plane (P) at the first side of the axis;
the second mirroring wall portion (22) has a center of curvature (24) which is situated in a region having the shape of an ellipse (Q) whose major axis has a first end (24') in the plane (P) at a distance of 0.02 d from the axis of symmetry (11) and a second end (24") at a distance of 0.07 d from the plane (P) and 0.13 d from the axis of symmetry, which ellipse has a major axis which is 6.8 times the length of the ellipse minor axis;
and
the light-transmissive window (30) has a largest diameter smaller than 0.8 d.

10 more elements

Abstract

Claims14