| CPC H02J 7/007188 (2020.01) [G02C 7/04 (2013.01); H02J 7/00308 (2020.01); H02J 50/10 (2016.02); G02C 11/10 (2013.01); H02J 7/02 (2013.01); H02J 2207/20 (2020.01); H02J 2310/23 (2020.01)] | 1 Claim |
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1. A contact lens charging system, comprising:
two contact lenses and a contact lens charger, each contact lens comprising:
a display comprising a femtoprojector configured to project light onto a wearer's retina;
a gyroscope, an accelerometer, a magnetometer, a radio transceiver, and a forward-looking imager;
a plurality of batteries, each in a separate package, mounted on a flexible board which is coiled into a shape of a truncated cone with a plurality of extensions for the gyroscope, accelerometer, magnetometer, radio transceiver, forward-looking imager and display, the batteries placed outside the area of a wearer's pupil;
a charging circuit, the charging circuit comprising a disabling circuit for disabling the charging circuit while the contact lens is being worn,
wherein the disabling circuit is configured to enable the charging circuit while the posterior surface of the contact lens is being illuminated by the contact lens charger with an irradiance of 10 mW/cm2, the irradiance being greater than a maximum irradiance incident on a scleral posterior surface of the contact lens while the contact lens is being worn,
wherein the disabling circuit comprises a first photodiode connected to a switch, the first photodiode configured to be illuminated through a window in an opaque layer of the disabling circuit, the first photodiode configured to be illuminated through a transparent portion of the contact lens, the first photodiode aimed at the sclera of the eye of the wearer while the contact lens is being worn,
wherein the disabling circuit comprises a second photodiode connected in series with the first photodiode,
wherein the disabling circuit comprises a first switch configured to interrupt a current path to an output of the charging circuit;
an energy storage device, comprising the plurality of batteries, the storage device connected to the charging circuit;
a coil, connected to an input of the charging circuit, for receiving electrical power inductively, wherein the charging circuit comprises an optically-enabled voltage multiplier connected to the coil, the voltage multiplier comprising an energy-storage capacitor that powers an overvoltage detection circuit for at least 1,000 milliseconds after an overvoltage condition is reached;
wherein the voltage multiplier has a first AC input terminal and a second AC input terminal and an overvoltage protection circuit comprising:
an overvoltage detection circuit,
a fuse, and
a shorting switch;
a first terminal of the coil is connected to the first AC input terminal through the fuse;
a second terminal of the coil is connected to the second AC input terminal; and
the shorting switch is connected across the first AC input terminal and the second AC input terminal;
wherein the voltage multiplier comprises a first rectifying stage and a second rectifying stage, and the first switch is connected between a DC output of the first rectifying stage and a DC input of the second rectifying stage;
wherein three disabling switches are connected to an output of the optically-enabled voltage multiplier;
wherein the optically-enabled voltage multiplier is configured to operate with an input RMS AC voltage of 1.5V and to generate, while an electronic contact lens is being charged, 5V at an output of the voltage multiplier, the 5V at the output of the voltage multiplier limited by a chain of seven forward-biased diodes;
wherein the charging circuit comprises a full-wave rectifier, connected to the coil and operatively coupled to the output of the charging circuit;
wherein the overvoltage detection circuit comprises a chain of nine diodes connected in a series, each diode in the chain, except a last diode, being connected to an anode of a next diode in the series, the chain of diodes forming a voltage divider having a high pass characteristic such that the overvoltage detection circuit triggers at a first voltage when the voltage increases rapidly and a second voltage when the voltage increases slowly, the first voltage being lower than the second voltage, a capacitor connected in parallel with the last diode; and,
the contact lens charger comprising:
a lens compartment, wherein the lens compartment is watertight and holds a fluid cleaning solution, the cleaning solution cleans the contact lens and keeps it cool during charging, and the charger includes an enabling system which enables charging of the contact lens by putting the disabling circuit in a charging-enabled state;
a light source that illuminates the posterior surface of the contact lens with light with an irradiance of 10 mW/cm2 at the photodiodes which exceeds the greatest irradiance expected to be incident on the scleral posterior surface of the contact lens while the electronic contact lens is being worn; and,
a charger drive coil in the charger which is inductively coupled to the coil of the contact lens.
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