Power delivery for accommodation by an eye-mountable device
View Patent ↗Techniques and mechanisms to power automatic accommodation by an eye-mountable device. In an embodiment, the eye-mountable device includes an accommodation actuator to change an optical strength of the eye-mountable device. Control logic of the eye-mountable device is to transition a supply voltage between different levels to drive operation of the accommodation actuator, including the control logic to perform a step-wise transition of the supply voltage from a first voltage level to a second voltage level. In another embodiment, the control logic includes a bidirectional direct current to direct current (DC-DC) converter. During the step-wise transition of the supply voltage, the bidirectional DC-DC converter is configured to aid in recharging a battery of the eye-mountable device with charge from the accommodation actuator.
1. An eye-mountable device, comprising:
an enclosure material;
an accommodation actuator disposed within the enclosure material;
a controller including integrated circuitry configured to provide the accommodation actuator with a supply voltage at a first level, to perform a step-wise transition of the supply voltage from the first level to a second level, wherein the controller successively maintains the supply voltage temporarily at each of one or more intermediate levels between the first level and the second level, and to provide the accommodation actuator with the supply voltage at the second level, wherein the eye-mountable device has a first optical strength in response to the first level of the supply voltage, and wherein the eye-mountable device has a second optical strength in response to the second level of the supply voltage;
a battery, wherein the controller comprises a bidirectional direct current to direct current (DC-DC) converter to recharge the battery with charge from the accommodation actuator during the step-wise transition of the supply voltage from the first level to the second level.
2. The eye-mountable device of claim 1 , wherein the accommodation actuator includes a liquid crystal cell.
3. The eye-mountable device of claim 1 , wherein a concave surface of the enclosure material is configured to be removeably mounted over a cornea and a convex surface of the enclosure material is configured to be compatible with eyelid motion when the concave surface is so mounted.
4. The eye-mountable device of claim 1 , the controller further to perform another step-wise transition of the supply voltage from the second voltage level to the first voltage level.
5. The eye-mountable device of claim 1 , the controller further to perform a linear transition of the supply voltage from the second level to the first level prior to the step-wise transition.
6. The eye-mountable device of claim 1 , wherein the supply voltage is a differential voltage across the accommodation actuator.
7. The eye-mountable device of claim 1 , wherein the controller to switchedly reverse a direction of coupling of the accommodation actuator between a node providing the supply voltage and a node providing a reference potential.
8. The eye-mountable device of claim 1 , the controller further to provide a sequence of cycles of the supply voltage, the cycles each including a respective step-wise transition of the supply voltage, wherein a frequency of the cycles is equal to or greater than sixty (60) Hertz.
9. The eye-mountable device of claim 1 , wherein the bidirectional DC-DC converter includes a series-parallel switched capacitor circuit.
10. The eye-mountable device of claim 1 , the controller further to receive an indication of a direction of gaze by a user of the eye-mountable device, wherein the controller to change a level of the supply voltage in response to the indication of the direction of gaze.
11. A method implemented by an eye-mountable device, the method comprising:
providing an accommodation actuator with a supply voltage at a first level, wherein the eye-mountable device includes an enclosure material and an accommodation actuator disposed within the enclosure material, wherein the eye-mountable device has a first optical strength in response to the first level of the supply voltage;
performing a step-wise transition of the supply voltage from the first level to a second level, including successively maintaining the supply voltage temporarily at each of one or more intermediate levels between the first level and the second level;
during the step-wise transition of the supply voltage from the first level to the second level, recharging a battery disposed within the enclosure material with charge from the accommodation actuator, wherein the battery is recharged with a bidirectional direct current to direct current (DC-DC) converter; and
providing the accommodation actuator with the supply voltage at the second level, wherein the eye-mountable device has a second optical strength in response to the second level of the supply voltage.
12. The method of claim 11 , wherein the accommodation actuator includes a liquid crystal cell.
13. The method of claim 11 , further comprising performing another step-wise transition of the supply voltage from the second voltage level to the first voltage level.
14. The method of claim 11 , further comprising performing a linear transition of the supply voltage from the second level to the first level prior to the step-wise transition.
15. The method of claim 11 , further comprising switchedly reversing a direction of coupling of the accommodation actuator between a node providing the supply voltage and a node providing a reference potential.
16. The method of claim 11 , further comprising:
providing a sequence of cycles of the supply voltage, the cycles each including a respective step-wise transition of the supply voltage, wherein a frequency of the cycles is equal to or greater than sixty (60) Hertz.
17. A contact lens, comprising:
an enclosure material, wherein a concave surface of the enclosure material is configured to be removeably mounted over a cornea and a convex surface of the enclosure material is configured to be compatible with eyelid motion when the concave surface is so mounted;
an accommodation actuator disposed within the enclosure material, the accommodation actuator including a liquid crystal cell;
a controller including integrated circuitry configured to provide the liquid crystal cell with a supply voltage at a first level, to perform a step-wise transition of the supply voltage from the first level to a second level, wherein the controller successively maintains the supply voltage temporarily at each of one or more intermediate levels between the first level and the second level, and to provide the accommodation actuator with the supply voltage at the second level, wherein the contact lens has a first optical strength in response to the first level of the supply voltage, and wherein the contact lens has a second optical strength in response to the second level of the supply voltage;
a battery, wherein the controller comprises a bidirectional direct current to direct current (DC-DC) converter to recharge the battery with charge from the accommodation actuator during the step-wise transition of the supply voltage from the first level to the second level.
18. The contact lens of claim 17 , the controller further to perform another step-wise transition of the supply voltage from the second voltage level to the first voltage level.
19. The contact lens of claim 17 , wherein the controller to switchedly reverse a direction of coupling of the accommodation actuator between a node providing the supply voltage and a node providing a reference potential.
20. The contact lens of claim 17 , the controller further to provide a sequence of cycles of the supply voltage, the cycles each including a respective step-wise transition of the supply voltage, wherein a frequency of the cycles is equal to or greater than sixty (60) Hertz.