Light source driving circuitry for electronic devices
First Claim
1. Circuitry, comprising:
- a signal generator that produces ramped pulses;
a differentiator that differentiates the ramped pulses to produce differentiated pulses;
a light source; and
an output driver circuit that receives the differentiated pulses and that supplies corresponding signal pulses to the light source, wherein the output driver circuit comprises a transistor having a gate that receives the differentiated pulses and wherein an output power of light emitted by the light source is controlled by the signal pulses.
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Accused Products
Abstract
An electronic device may have control circuitry and input-output components. The input-output components may include audio components, sensors, and other devices. A proximity sensor may supply the control circuitry with proximity sensor data. The control circuitry may adjust the audio components or take other suitable action in response to proximity sensor readings from the proximity sensor. The proximity sensor may have a light source such as an infrared laser diode and a light detector that measures a reflected portion of infrared light pulses emitted by the infrared laser diode. The control circuitry may include circuitry for safely producing pulses of emitted light with the light source. This circuitry may include a signal generator that produces ramped pulses, a differentiator that differentiates the ramped pulses to produce differentiated pulses, and an output driver that produces current pulses for the light source based on the differentiated pulses.
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Citations
19 Claims
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1. Circuitry, comprising:
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a signal generator that produces ramped pulses; a differentiator that differentiates the ramped pulses to produce differentiated pulses; a light source; and an output driver circuit that receives the differentiated pulses and that supplies corresponding signal pulses to the light source, wherein the output driver circuit comprises a transistor having a gate that receives the differentiated pulses and wherein an output power of light emitted by the light source is controlled by the signal pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method, comprising:
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with a signal generator that includes an operational amplifier, supplying signal pulses to a differentiator; with the differentiator, differentiating the signal pulses to produce differentiated pulses; with an output driver circuit, supplying drive signal pulses to a light source in response to receiving the differentiated pulses; and with the light source, emitting pulses of infrared light in response to the drive signal pulses. - View Dependent Claims (15, 16)
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17. An electronic device, comprising:
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a proximity sensor having a light source that is controlled by current pulses to produce pulses of infrared light and having a light detector that measures reflected portions of the pulses of infrared light to produce proximity sensor readings; and control circuitry coupled to the proximity sensor, wherein the control circuitry includes; a signal generator that produces signal pulses; a differentiator that differentiates the signal pulses to produce differentiated signal pulses, wherein the signal generator includes an operational amplifier and a switch coupled between the operational amplifier and the differentiator; and an output driver circuit that receives the differentiated signal pulses and that supplies the current pulses to the light source based on the differentiated signal pulses. - View Dependent Claims (18, 19)
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Specification