Apparatus and method for pulsed L.E.D. illumination
First Claim
1. An apparatus comprising:
- at least one light-emitting diode (LED);
a DC voltage source that has an amount of electrical power;
a pulse-controller circuit operatively coupled to the voltage source and to the at least one LED that;
in a constant-light-output-characteristic mode, withdraws pulsed current from the DC voltage source and supplies power from the withdrawn pulsed current to the at least one LED such that a characteristic of light output from the at least one LED remains substantially constant as the amount of electrical power remaining of the DC voltage source varies over a range that would otherwise change the light-output characteristic of the at least one LED, andin a power-indication mode, controls at least one visibly perceptible light-output characteristic of the at least one LED such that the at least one visibly perceptible light-output characteristic provides an indication to a human user of a remaining portion of the amount of electrical power.
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Accused Products
Abstract
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.
73 Citations
20 Claims
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1. An apparatus comprising:
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at least one light-emitting diode (LED); a DC voltage source that has an amount of electrical power; a pulse-controller circuit operatively coupled to the voltage source and to the at least one LED that; in a constant-light-output-characteristic mode, withdraws pulsed current from the DC voltage source and supplies power from the withdrawn pulsed current to the at least one LED such that a characteristic of light output from the at least one LED remains substantially constant as the amount of electrical power remaining of the DC voltage source varies over a range that would otherwise change the light-output characteristic of the at least one LED, and in a power-indication mode, controls at least one visibly perceptible light-output characteristic of the at least one LED such that the at least one visibly perceptible light-output characteristic provides an indication to a human user of a remaining portion of the amount of electrical power. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of operating an illumination device having at least one light-emitting diode (LED) and a DC voltage source that has an amount of electrical power;
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withdrawing pulsed current from the DC voltage source; in a constant-light-output-characteristic mode, supplying power from the withdrawn pulsed current to the at least one LED such that a characteristic of light output from the at least one LED remains substantially constant as the amount of electrical power remaining of the DC voltage source varies over a range that would otherwise change the light-output characteristic of the at least one LED; and in a power-indication mode, controlling at least one visibly perceptible light-output characteristic of the at least one LED such that the at least one visibly perceptible light-output characteristic provides an indication to a human user of a remaining portion of the amount of electrical power. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. An apparatus comprising:
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at least one light-emitting diode (LED); a DC voltage source that having an amount of electrical power; a pulse-controller circuit operatively coupled to the voltage source and to the least one LED that selectively controls a pulse-switched connection of the voltage source to the pulse-controller circuit, and has a first mode of operation that supplies electrical power to the least one LED to maintain an average light output of the least one LED at a predetermined level by adjusting a parameter of the pulse-switched connection, wherein the parameter includes at least one of the group consisting of a pulse width and a pulse frequency, in order to maintain the average light output at the predetermined level, wherein the pulse-controller circuit also has a second mode of operation that outputs a series of visibly perceptible light pulses to provide a visibly perceptible indication of a remaining amount of the electrical power in the voltage source, wherein the visibly perceptible light pulses include a number of visibly perceptible pulses followed by a time period with one or more dropped light pulses, the number being proportional to the remaining portion of the amount of electrical power. - View Dependent Claims (17, 18, 19)
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20. An apparatus comprising:
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at least one light-emitting diode (LED); a DC voltage source that having an amount of electrical power; a pulse-controller circuit operatively coupled to the voltage source and to the least one LED that selectively controls a pulse-switched connection of the voltage source to the pulse-controller circuit, and has a first mode of operation that supplies electrical power to the least one LED to maintain an average light output of the least one LED at a predetermined level by adjusting a parameter of the pulse-switched connection, wherein the parameter includes at least one of the group consisting of a pulse width and a pulse frequency, in order to maintain the average light output at the predetermined level, wherein the at least one LED includes a plurality of light-emitting diodes (LEDs), and wherein the pulse-controller circuit also has another mode of operation that provides a visibly perceptible indication of a remaining amount of the electrical power in the voltage source by controls the power supplied to the plurality LEDs such that how many of the plurality of LEDs are illuminated provide the indication to a human user of a remaining portion of the amount of electrical power.
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Specification