Electricity: motive power systems – Three-or-more-positions motor controller systems – Plural – diverse or diversely controlled controllers
Reexamination Certificate
2000-02-08
2001-02-20
Ip, Paul (Department: 2837)
Electricity: motive power systems
Three-or-more-positions motor controller systems
Plural, diverse or diversely controlled controllers
C318S017000, C318S055000, C396S012000, C348S144000, C362S035000, C362S277000
Reexamination Certificate
active
06191547
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a focus control for search lights. More particularly, the present invention is directed to a bidirectional focus control for search lights.
BACKGROUND OF THE INVENTION
Search lights are extensively used on police and rescue helicopters to illuminate subjects on the ground and in the water. Generally, search lights are mounted on gimbles which enable the search lights to be angularly adjusted with respect to helicopters in order for the light beams of the search lights to remain in alignment with subjects under scrutiny. This is necessary because a subject may move with respect to a helicopter, either as the helicopter moves, or when the helicopter is substantially stationary and the subject moves. It is frequently necessary to first illuminate a relatively large area in order to locate whatever subject is of interest and then to progressively illuminate smaller and smaller areas in order to isolate the subject so that the subject can be readily discernable by a helicopter crew or other observers either on the ground or at another location.
Currently, the focus of a search light beam from a helicopter mounted search light is adjusted by a uni-directional cam which is driven to rotate in only one direction by a DC motor. Consequently, if a desired focus angle has been passed and one wishes to change the size of an area illuminated, there is a lag period as the uni-directional cam recycles. This can result in the subject being observed either escaping from or unintentionally moving out of an illuminated area. It is therefore desirable to rotate the cam in both directions in order to enhance an operator's ability to maintain a desired illuminated area or to rapidly change the size of the area without recycling the cam.
In helicopters and fixed-wing aircraft, search lights are generally connected by a connecting wire harness to internal cable systems within the fuselage of the helicopter or aircraft. In accordance with standard practice, there is only a single wire in the connecting wire harness devoted to interfacing with the focus control for the search lights, which focus control axially moves bidirectionally according to the rotational position of the uni-directional cam. Normally in order to make the cam bidirectional, the DC motor must run in both directions. In the prior art bidirectional motor rotation requires two wires, one for each direction of cam rotation. In order to provide a second wire in the wire harness, the wire harness must be changed or re-engineered. Moreover, after the wire harness has been changed or re-engineered, the helicopter or aircraft must be inspected by licensing authorities and the new wiring arrangement approved before the aircraft or helicopter is legally allowed to fly. This is an expensive, time-consuming undertaking which requires not only re-wiring of the connecting harness but also re-wiling of the search lights and search light controls. Consequently, helicopters and aircraft already equipped with search lights having a single wire for focus control forego improvements in focus control which would enable focus control to proceed in both directions rather than a single direction.
In view of the aforementioned considerations, there is a need for an arrangement which allows a search light on a helicopter or an aircraft to be modified in order to have a bidirectional focus control without having to do any re-wiring.
While this problem is primarily a problem with search lights mounted on platforms such as helicopters and fixed wing aircraft, it is also a consideration for other platforms such as search lights mounted on boats and land vehicles and even those mounted on remotely controlled stationary supports.
SUMMARY OF THE INVENTION
It is a feature of the present invention to provide a new and improved focus control for a search light wherein the focus control is bidirectional and requires but a single control wire interface with a control station remote from the search light.
The present invention is directed to a focus control for narrowing and widening the focus angle of a search light beam emitted by a search light mounted on a platform having a power source. The search light includes a motor, a cam driveable by the motor to rotate and a focus control operated by the cam for narrowing and widening the focus angle in response to control signals over a single wire interface between a remotely positioned control switch and the motor. The remotely positioned control switch has an open position, a power source position and a ground position, wherein when the remotely positioned control switch is in the power source position, the single wire interface is in a first state different from a second state of the single wire interface which occurs when the remotely position control switch is in the ground position. A switching circuit is connected between the power source and the motor for reversing polarity of current flowing through the motor. The switching circuit is connected to the remotely positioned control switch by the single wire interface and includes an input responsive to a change in state of the single wire interface, which input reverses the polarity of current flowing through the motor to reverse rotation of the motor and thus the cam. When rotation of the cam reverses, the direction of the focus angle magnitude reverses.
In another aspect of the invention, the motor is a DC motor and circuitry is included for connecting both poles of the DC motor to ground when the remotely positioned switch is in the open position.
In still another aspect of the invention, diodes suppressing voltage spikes are provided between the first and second poles of the motor and the power source, as well as between the poles and ground.
In still another aspect of the invention, the input comprises a pair of coils, one connected to the power source and the other connected to ground. Both coils are directly connected to the single wire interface, whereby a change in state of the single wire interface deenergizes one coil while the other coil remains energized. The coils are each associated with a bipolar switch connected to the DC motor and disposed between ground and the power source, the bipolar switches individually changing connections to reverse polarity of current flowing through the DC motor as the coils are individually deenergized due to changes in state of the single wire interface.
Aspect of the invention, in order to protect the coils, protective diodes are disposed between the power source of the coils and the single wire interface, as well as between ground and the single wire interface.
In still a further aspect of the invention, the switching circuit is a double-pole, single-throw dual relay.
In a more specific aspect of the invention, the platform upon which the search light is mounted is a helicopter or fixed wing aircraft having a fuselage; the search light being mounted on the helicopter or aircraft at a location exterior to the fuselage and the remotely positioned switch being within the fuselage and connected to the switching circuit by the single wire interface.
In still another aspect of the invention, the switching circuit includes a double-pole, single-throw dual relay and includes circuitry for connecting both poles of the DC motor to ground when the remotely positioned switch is in the open position.
REFERENCES:
patent: 3634677 (1972-01-01), Stuttgart
patent: 3979649 (1976-09-01), Persha
patent: 3987296 (1976-10-01), Coppola et al.
patent: 5030886 (1991-07-01), Darrow
patent: 5490046 (1996-02-01), Gohl et al.
patent: 5589901 (1996-12-01), Means
patent: 5673989 (1997-10-01), Gohl et al.
patent: 5806956 (1998-09-01), Hyun-Jo
“SX-16 Nightsun Searchlight” (Jan. 1988) Spectrolab, Inc., Operation and Maintenance Instructions (9 pages).
“Starburst Searchlight Model SX-5” (Jan. 1988) Spectrolab, Inc. Operation and Maintenance Instructions (8 pages).
Fricke Kenneth J.
Mendez David
Gudmestad T.
Hughes Electronics Corporation
Ip Paul
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