Improved method and apparatus for hand-held portable LED illumination. The illumination source includes a plurality of LEDs, and an electrical circuit that selectively applies power from the DC voltage source to the LED units, wherein the illumination source is suitable for handheld portable operation. In some embodiments, the electrical circuit further includes a control circuit for changing a proportion of light output having the first characteristic color spectrum output to that having the second characteristic color spectrum output, and that drives the LEDs with electrical pulses at a frequency high enough that light produced has an appearance to a human user of being continuous rather than pulsed. Still another aspect provides an illumination source including a housing including one or more LEDs; and a control circuit that selectively applies power from a source of electric power to the LEDs, thus controlling a light output color spectrum of the LEDs.

Method and apparatus for a variable intensity pulsed L.E.D. light

Solid state optically coupled power switch with light induced or modified voltage applied or removed at one or more MOSFET gate and source electrode pairs to shift each MOSFET between its high and low impedance states and in various circuit arrays for ac or dc switching and/or cross points switching or mechanical Form C relay substitution or other purposes

Solid state optically coupled electrical power switch

An overcurrent protection circuit for AC systems is provided including a means for developing a full wave DC sensing voltage whose peak magnitude is proportional to the load current of the system to be protected and that sensing voltage is applied to an optical isolator whose secondary circuit includes an optically responsive device having a conduction threshold voltage in a predetermined relation to the sensing voltage magnitude for normal load current; the secondary circuit also includes means responsive to current through the optically responsive device to result in an overcurrent trip signal upon occurrence of predetermined overcurrent conditions. The overcurrent protection circuit is particularly suitable for use in solid state power controllers and imposes minimal power supply requirements as compared with prior circuits for this purpose while exhibiting good performance and reliability.

Overcurrent protection circuit for ac systems

A bilateral switch uses a single photodiode array (PDA) connected to the gate electrode of a voltage controlled device such as a field effect transistor (JFET) or an antiparallel connected gated diode switch pair (GDS, GDSa) and, through appropriate diodes, to the drain and source electrodes of the field effect transistor or to the anode and cathode of the gated diode switch to control the current through the voltage controlled device. The photodiode array is optically coupled to a light-emitting diode (LED) located in an electrical input circuit.

Optically triggered linear bilateral switch

An illumination source for a camera includes one or more LEDs, and an electrical circuit that selectively applies power from the DC voltage source to the LEDs, wherein the illumination source is suitable for handheld portable operation. In some embodiments, the electrical circuit further includes a control circuit for driving the LEDs with electrical pulses at a frequency high enough that light produced has an appearance to a human user of being continuous rather than pulsed, the control circuit changing a pulse characteristic to adjust a proportion of light output having the first characteristic color spectrum output to that having the second characteristic color spectrum output. Some embodiments provide an illumination source including a housing including one or more LEDs; and a control circuit that selectively applies power from a source of electric power to the LEDs, thus controlling a light output color spectrum of the LEDs.

Method and apparatus for pulsed L.E.D. illumination for a camera

A solid-state relay utilizing a light-emitting diode to transmit optical energy steadily to a photo-sensitive solid-state device to control the conductivity of solid -state elements. A relatively low power source of AC or DC can be used to operate photo-sensitive uni-junction transistor or a pair of light-activated silicon-controlled rectifiers.

Michael F Joyce

Papers

Solid-state relay using light-emitting diodes