Loading patent…
AssigneeHoneywell International Inc.
InventorsDuane F. Melvin, Saed M. Mubaslat
Estimating the term…
A solid state control switching and control system (200) for retractable landing lights. A control unit (208) uses an absolute position sensor (214) to monitor the position of the lighthead (210) of the retractable landing light, and actuates a motor (216), brake (217), and lamp (212) in response to command signals (220,221,223) from the flight crew. Actuation of the motor (216), brake (217), and lamp (212) with solid state switches (100) is gradual and synchronized to minimize electromagnetic interference and extend component life.
A solid state switching system for a retractable vehicle light, comprising:
A solid state switching system for a retractable vehicle light, comprising:
A solid state switching system for a retractable vehicle light, comprising:
A process for controlling a retractable vehicle light, comprising:
A process for controlling a retractable vehicle light, comprising:
A process for controlling a retractable vehicle light, comprising:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
From the US filing history. Foreign family members aren’t listed.
Arrangements or adaptations of signal or lighting devices: the lighting devices being primarily intended to illuminate the way ahead
Without feedback from the output circuit to the control circuit: soft switching
The output circuit comprising more than one controlled field-effect transistor: in a symmetrical configuration
Using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled: controlling field-effect…
Term ended 23 May 2022 (estimated)
This application claims the benefit of U.S. Provisional Application No. 60/339637 filed Dec. 12, 2001 entitled EFFICIENT AC/DC SOLID STATE SWITCHING SYSTEM FOR AIRCRAFT LANDING LIGHTS.
1. Field of the Invention
This invention relates to a switching and control system for an aircraft retractable landing light. Specifically, this invention relates to a switching and control system for an aircraft retractable landing light having solid state AC/DC switching and improved load control.
These and other features will become better understood with reference to the following description, appended claims, and accompanying drawings.
FIG. 1 is an electrical schematic diagram of the solid state switch;
FIG. 2 is an electrical block diagram of the general arrangement of the solid state switch and associated loads; and
An electrical schematic diagram of a solid state switch 100 is shown in FIG. 1. High-level electrical AC or DC power to be switched is applied to the input terminals 102,103. A logical control voltage is applied to an input terminal 104. The voltage at input terminal 104 is supplied to a resistor-capacitor “R-C” network 105,106, which is in turn connected to at least one light emitting diode 108 packaged within a photovoltaic isolator 110. A resistor 107 provides current limiting for the light emitting diodes 108. When a control switch 122 is closed, current gradually flows through the light emitting diodes 108 as capacitor 106 charges, causing the light emitting diodes 108 to radiate light. The light emitted by the light emitting diodes 108 is optically coupled to at least one photovoltaic generator 112 packaged within photovoltaic isolator 110, causing the photovoltaic generators 112 to generate a galvanically isolated current. The values of resistor 105 and capacitor 106 may be changed as desired to slow the turn-on and turn-off times of the light emitting diodes 108 when switch 122 is closed and opened respectively, resulting in a current generated by the photovoltaic isolators 112 with proportionally slow characteristics.
The current generated by the photovoltaic generators 112 is coupled to the gates of two N-Channel MOSFETS 114,115 via a pair of gate bias resistors 116. This current gradually charges the inherent gate-to-source capacitance of the MOSFETS 114,115, causing the MOSFETS 114,115 to slowly begin conducting current to the load, which is connected to the output terminals 124,125. The gradual increase and decrease in the current generated by the photovoltaic isolators 112 combined with the gradual increase and decrease of the gate voltage of the MOSFETs 114,115 through the charging and discharging of the gate-to-source capacitance of the MOSFETs 114,115 results in a “soft switch,” reducing electrical stress at turn-on and turn-off for both the MOSFETs 114,115 and loads such as the motor 216, brake 217, and lamp 212, shown in FIG. 2. This results in increased service life for the solid state switches 114,115 and a motor 216, brake 217, or lamp 212, while reducing electromagnetic emissions. The lagging on-off response time of the MOSFETS 114,115 associated with the gradual charging and discharging of the gate-to-source capacitance of the MOSFETS 114,115 also provides “hysteresis” means when the solid state switch 100 is part of a totem-pole or H-bridge power driver. This hysteresis prevents excessive currents and electromagnetic emissions that may occur when a voltage source is momentarily shorted to ground as a result of contention during switching of totem-pole or H-bridge power drivers. As previously discussed, the soft start and hysteresis characteristics inherent to the photovoltaic generators 112 and the MOSFETs 114,115 are augmented by means for gradually turning the light emitting diodes 108 on and off, such as with resistor 105 and capacitor 106. Varying the resistance of resistor 105 and the capacitance of capacitor 106 results in faster or slower turn-on and turn-off of the light emitting diodes 108, providing a means to adjust the amount of soft-switching control of solid state switch 100. The turn-on and turn-off time of the light emitting diodes 108 may be increased by increasing the R-C time constant of resistor 105 and capacitor 106. Conversely, the turn-on and turn-off time of the light emitting diodes 108 may be decreased by lowering the R-C time constant of resistor 105 and capacitor 106. The turn-on and turn-off time of the MOSFETs 114,115 may be further increased by adding a capacitor 117 to the photovoltaic generators 112. The turn-on and turn-off time of the MOSFETs 114,115 may also be increased by adding a pair of capacitors 119 to the gate drive circuits of the MOSFETs 114,115.
The low drain-to-source resistance inherent to the MOSFETS 114,115 when saturated minimizes I2R losses and resultant heat, making the solid state switch 100 an efficient switch for use with both AC and DC loads. MOSFETs 114,115 act as an electrical switch with galvanically isolated on-off control. When MOSFETs 114,115 are active, AC or DC current may flow from the drain terminals to the source terminals of the MOSFETs 114,115; electrical current may also flow from the source terminals to the drain terminals of the MOSFETs 114,115. The body diodes 126,128, which are integral to MOSFETs 114,115, serve to block the flow of electrical current through the solid state switch 100 when the MOSFETs 114,115 are in an off state.