IrDA transceiver module that also functions as remote control IR transmitter
First Claim
1. A method, comprising:
- providing an inductor in a current path through which an LED drive current is provided to an infrared light emitting diode (LED) of an IrDA transceiver module, wherein the LED drive current is no more than 265 mA when the IrDA transceiver module is transmitting an IrDA transmission, and wherein the LED drive current is no more than 400 mA when the IrDA transceiver module is transmitting an RC transmission.
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Accused Products
Abstract
The infrared LED of an IrDA module transmits IR energy with a peak wavelength (for example, 875 nm) appropriate for IrDA communication. This peak wavelength is lower than is the wavelength (for example, 940 nm) used in ordinary IR remote controls (RC). The IrDA LED does, however, transmit some energy at the wavelength of the peak sensitivity of an RC receiver. When making an IrDA transmission, the IrDA LED is driven with a lower amount of current. When making an RC transmission, the IrDA LED is driven with an increased amount of current such that higher wavelength emissions received by the RC receiver are of adequate power to realize RC communication. A passive circuit is disclosed for automatically increasing IrDA LED current during RC transmissions. The circuit involves an inductor that shunts current around a current-limiting resistor used to limit LED drive current.
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Citations
18 Claims
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1. A method, comprising:
providing an inductor in a current path through which an LED drive current is provided to an infrared light emitting diode (LED) of an IrDA transceiver module, wherein the LED drive current is no more than 265 mA when the IrDA transceiver module is transmitting an IrDA transmission, and wherein the LED drive current is no more than 400 mA when the IrDA transceiver module is transmitting an RC transmission.
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2. A circuit, comprising:
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a transceiver module having a single light emitting diode (LED), wherein the transceiver module generates a first type of signal having an intensity of radiation emitted from the LED that is at least 40 mW/steradian at a wavelength of less than 900 nm, and wherein the transceiver module generates a second type of signal having an intensity of radiation emitted from the LED that is at least 40 mW/steradian at a wavelength of greater than 900 nm; and a passive current-limiting circuit that limits an LED drive current flowing through the LED to a first average current value when the LED is generating the first type of signal, and that limits the LED drive current to a second average current value when the LED is generating the second type of signal. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system, comprising:
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a transceiver module usable for transmitting both a first type of signal and a second type of signal, wherein the first type of signal has an intensity of radiation that is at least 40 mW/steradian at a wavelength of less than 900 nm, and wherein the second type of signal has an intensity of radiation that is at least 40 mW/steradian at a wavelength of greater than 900 nm; a passive current-limiting circuit, wherein the transceiver module receives an LED drive current from the passive current-limiting circuit; and a processor that supplies a signal with a first modulation to the transceiver module such that the transceiver module generates the first type of signal with a first average infrared emission intensity, the processor also supplying a signal with a second modulation to the transceiver module such that the transceiver module generates the second type of signal with a second average infrared emission intensity, the second average infrared emission intensity being substantially greater than the first average infrared emission intensity, and wherein both the first type of signal and the second type of signal are generated using a single infrared light emitting diode (LED) disposed on the transceiver module. - View Dependent Claims (15, 16, 17, 18)
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Specification