Controller for lamp having more than one light source

Abstract

A controller for controlling operation of a multi-filament lamp is provided that permits selection of the filament to be energized from a control box placed at a remote location from the lamp. Only two leads are required to electrically connect the control box to the lamp. The controller automatically switches energizing power from a burned out filament to an alternate filament. The controller can also include a source of alternate power for the controller in the event that primary power is lost. The controller can also include a lock out feature which prevents switching energizing power at the control box from an energized filament to a failed filament.1. Field of the InventionThe present invention relates to controllers for lamps and, in particular, a controller for a lamp having more than one light source that permits control of the lamp from a location remote from the lamp.2. Description of the Prior ArtLamps having more than one light source are known generally and are useful during the performance of surgical procedures. Such lamps provide a readily available source of light upon failure of one of the light sources of the lamp. For example, the lamp disclosed in U.S. Patent Application Ser. No. 936,240 filed Aug. 24, 1978, discloses a lamp having multiple filaments, each of which provides light having a pattern different from those provided by the remaining sources.Although lamps having more than one light source are more useful during performance of surgical procedures than are lamps with a single light source, several problems are associated with their use. First, the selection of which light source is energized must be made at the lamp head. Further, the switch to an alternate light source upon failure of an energized light source must be accomplished manually which causes a temporary loss of light.SUMMARY OF THE INVENTIONThe present invention provides a controller for a lamp having more than one light source that permits selection of which light source is energized at a location that is remote from the lamp head. Accordingly, personnel performing surgical procedures need not effect light source selection at the lamp head. Further, the present invention senses failure of a light source and automatically switches energizing current to an alternate light source. The apparatus of the present invention which is separated spatially from the lamp head is connected electrically to the lamp head with only two leads. Accordingly, the present invention can be installed easily in existing lamps which receive electrical power through only two leads. New lamps manufactured with the present invention installed are less complicated mechanically and less expensive than lamps which require three or more leads connected between the lamp head and the remotely located control apparatus.The controller of the present invention includes apparatus separated spatially from the lamp for receiving electrical power from a primary source of electrical power and impressing across two leads which communicate electrically with the lamp an electrical potential capable of producing in the leads an electrical current suitable for energizing the light sources. The receiving apparatus includes apparatus for reversing the direction of flow of the energizing current by reversing the polarity of the electric potential. The controller also includes apparatus located at the lamp for permitting energizing current to flow through a light source, which light source is energized depending on the direction of flow of the energizing current. The controller also includes apparatus separated spatially from the lamp for automatically reversing the polarity of the electric potential upon failure of the light source that is energized by the energizing current.The receiving apparatus can include apparatus for preventing the reversing apparatus from effecting a reversal of the polarity of the electric potential that would energize a failed light source. Further, the controller can include an alternate source of electrical power suitable for energizing the light sources and apparatus for supplying power from the alternate source to the controller upon failure of the primary source. Also, the controller can include apparatus separated spatially from the lamp for varying the intensity of the light produced by the light sources.Preferably, the elements of the invention that are separated spatially from the lamp are located in a control box mounted at a convenient location. Reversal of the polarity of the electric potential can be accomplished by a bridgeconfigured switching apparatus comprising four switching devices. The polarity of the impressed voltage depends on which set of two switching devices is conducting. The apparatus for permitting energizing current to flow through one light source is, preferably, a diode.When used herein, the terms "light source" and "filament" shall include elements through which electrical current flows to cause the elements to emit light.

Description

Claims

1. A controller for a lamp having more than one light source comprising:

a control box adapted for placement at a location that is remote from the lamp;

means disposed in said control box for reducing the level of the alternating voltage supplied to said controller to at least one level suitable for energizing the light sources;

means for converting said reduced alternating voltage to a direct voltage having a substantially constant amplitude capable of producing an electrical current suitable for energizing the light sources;

bridge-configured switching means having switching devices which can conduct or block electrical current for impressing said direct voltage across two leads which communicate electrically with the lamp, the polarity of said impressed voltage depending upon which of said switching devices are conducting;

means for causing said switching means to reverse the polarity of said impressed voltage;

means for automatically causing said switching means to reverse the polarity of said impressed voltage upon failure of a light source to which said impressed voltage is applied; and

means operatively connected to each light source for permitting current flow through said light source in only one direction, reversal of the polarity of said impressed voltage causing the direction of current flow through the lamp to be reversed and causing one light source to be extinguished and a second light source to be energized.

2. The controller recited in claim 1 further comprising

a source of alternate electrical power suitable for energizing the light sources; and

means for applying power from said alternate power source to said switching means upon failure of said supplied voltage.

3. A controller for a lamp having two sets of light sources, each set having at least one light source comprising:

means separated spatially from the lamp for receiving electrical power from a primary source of electrical power and impressing across two leads which communicate electrically with the lamp an electrical potential capable of producing in said leads an electrical current suitable for energizing the light sources, said receiving means including means for reversing the direction of flow of said energizing current by reversing the polarity of said electrical potential;

means located at the lamp for permitting energizing current to flow through one set of light sources, which set is energized by said permitting means depending on the direction of flow of said energizing current;

means separated spatially from the lamp for automatically reversing the polarity of said electrical potential upon failure of a light source that is energized by said energizing current;

means for preventing a reversal of the polarity of said electrical potential that represents an attempt to energize a failed light source;

an alternate source of electrical power suitable for energizing said light sources;

means for supplying power from said alternate source to said controller upon failure of said primary source; and

means separated spatially from the lamp for varying the intensity of the light produced by the light sources.