Communication using bi-directional LEDs
AssigneeMitsubishi Electric Research Laboratories, Inc.
InventorsPaul H. Dietz, William S. Yerazunis, Darren L. Leigh, Giovanni Vannucci
Life of this patent
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Abstract
An optical communications transceiver includes an LED coupled in series with a resistor. A microprocessor has one I/O pin connected to the LED. In a first mode or transmit mode, the LED is periodically driving in forward bias to emit light to transmit data. In a second or receive mode, the LED is periodically not driven in reverse bias, e.g., reverse bias or zero bias. Then, the LED is allowed to change charge of the capacitance of the LED's junction using a photo-current. The change in charge is measured using a timer. When the change in charge exceeds a predetermined threshold, input light is sensed. Thus, the LED can be used to receive data in the second mode.
Claims14
An optical communications transceiver, comprising:
- means for periodically driving an LED in forward bias to emit light to transmit data;
- means for periodically not driving the LED in forward bias;
- and means for measuring a time interval, the time interval dependent on a change in capacitance of the LED, the change in capacitance proportional to an amount of light sensed by the LED, wherein the LED is coupled in series with a resistor and a microprocessor having a first I/O pin connected to the LED and a second I/O pin coupled to the resistor, and in which the microprocessor includes the means for periodically driving the LED in forward bias and the means for periodically not driving the LED in forward bias and the means for measuring the time interval.
An optical communications transceiver, comprising:
- an LED coupled in series with a resistor;
- a microprocessor having a first I/O pin connected to the LED and a second I/O pin coupled to the resistor, in which the microprocessor further comprises:
- means for periodically driving the LED in forward bias to emit light to transmit data;
- means for periodically driving the LED in reverse bias;
- means for measuring a time interval, the time interval dependent on a change in capacitance of the LED, the change in capacitance proportional to an amount of light sensed by the LED.
An optical communications transceiver, comprising:
- an LED coupled in series with a resistor;
- a microprocessor having an I/O pin connected to the LED and ground coupled to the resistor, in which the microprocessor further comprises:
- means for periodically driving the LED in forward bias by setting the I/O pin to high to emit light for transmitting data;
- means for periodically driving the LED in zero bias by setting the I/O pin to low, and then setting the I/O pin to input to optically charge the LED;
- and
- means for measuring a time interval, the time interval dependent on a change in capacitance of the LED, the change in capacitance proportional to an amount of light sensed by the LED.
An optical communications transceiver, comprising:
- an LED coupled in series with a resistor;
- a microprocessor having an I/O pin connected to the resistor and ground coupled to the LED in which the microprocessor further comprises:
- means for periodically driving the LED in forward bias by setting the I/O pin to high to emit light for transmitting data;
- means for periodically driving the LED in zero bias by setting the I/O pin to low, and then setting the I/O pin to input to optically charge the LED;
- and
- means for measuring a time interval, the time interval dependent on a change in capacitance of the LED, the change in capacitance proportional to an amount of light sensed by the LED.
A method for transceiving data, comprising:
- periodically driving an LED in forward bias to emit light to transmit data, in which the LED is coupled in series with a resistor, and a microprocessor has an I/O pin connected to the resistor and ground coupled to the LED;
- periodically not driving the LED in forward bias, and then optically changing a charge of a capacitance of the LED after not driving the LED in forward bias;
- and
- measuring a time interval, the time interval dependent on a change in capacitance of the LED, the change in capacitance proportional to an amount of light sensed by the LED.
Dependencies are inferred from the claim text.