H-bridge Control Circuit for Ophthalmic Lens Driver
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ophthalmic lens drivers are unsuitable for ophthalmic devices due to high current consumption, limited voltage output, and size constraints, making them inefficient for powering variable-focus optic lenses, especially in contact lenses and intraocular lenses, which require precise voltage control and low power consumption to ensure extended operation and comfort.
Innovation Solution
A high-voltage H-bridge control circuit using N-channel and P-channel MOSFET transistors with level shifter cells and a charge pump cell to efficiently manage voltage and reduce current consumption, integrated into a compact form suitable for ophthalmic devices, allowing for safe, long-term, and reliable power delivery to variable-focus optic lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If existing lens drivers are used to power variable-focus optic lenses, then voltage control capability is provided, but current consumption is excessively high and device size exceeds constraints
Solution Approach 1:
The patent transforms the lens driver architecture from conventional voltage-source designs to a charge-pump-based system that operates with variable voltage levels. The charge pump generates high voltage only when needed to charge the lens capacitor, then operates at low voltage during maintenance phases. This dynamic parameter change reduces average current consumption from milliampere levels to microampere levels while maintaining the ability to provide high voltage when required for focus adjustment.
Solution Approach 2:
The lens driver employs periodic charging cycles where the charge pump activates intermittently to replenish charge in the lens capacitor rather than maintaining continuous high voltage. The control circuit monitors lens charge status and triggers charge pump operation only when threshold levels are reached. This periodic operation pattern dramatically reduces average power consumption while ensuring the lens receives adequate charge for focus modulation.
2Power
If high voltage is supplied to the optic element, then focus control capability is improved, but current consumption increases significantly
Solution Approach 1:
The patent introduces a charge pump circuit as an intermediary between the low-voltage power source and the high-voltage lens element. The charge pump acts as a voltage transformation mediator that converts low-voltage high-current power source output into high-voltage low-current output suitable for the lens. This intermediary device enables high voltage operation while maintaining low current consumption by decoupling the voltage and current characteristics through electromagnetic induction or capacitive multiplication.
Solution Approach 2:
The charge pump dynamically changes voltage parameters based on operational requirements. During focus adjustment, it generates high voltage (e.g., 30-60V) to charge the lens capacitor. During idle periods, it operates at low voltage or remains dormant. The control circuit adjusts the charge pump duty cycle and output voltage level to match the actual charge needs of the lens, thereby optimizing the power-voltage-current relationship and minimizing energy consumption while maintaining adequate voltage output capability.
3Volume of moving object
If compact packaging is implemented, then device size is reduced, but heat dissipation capability is limited
Solution Approach 1:
The charge pump operates in periodic bursts rather than continuously, activating only when the lens capacitor requires charge replenishment. During idle periods between charging cycles, the device generates minimal heat. This intermittent operation pattern allows the compact device to dissipate heat effectively during off-periods while maintaining high voltage output capability during active periods, thereby managing thermal load within the constrained volume without requiring large heat sinks or cooling systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces active current to approximately three microamperes and standby current to nanoamperes or picoamperes, enabling extended battery life and compact packaging without compromising comfort or performance, suitable for ophthalmic applications.
Implementation Method 1
a charge pump cell, wherein the capacitors level shift between a low voltage and a high voltage and transfer the charge to the charge pump cell, the charge pump cell provides an activation voltage for the first and second upper P-channel MOSFET switches
Implementation Method 2
the level shifter cells comprising buffers, a capacitor coupling circuit, and a charge pump cell, wherein the capacitors level shift between a low voltage and a high voltage and transfer the charge to the charge pump cell
Data Source
AI summary
A lens driver or lens driver circuitry for an ophthalmic apparatus comprising an electronic system which actuates a variable-focus optic is disclosed herein. The lens driver is part of an electronic system incorporated into the ophthalmic apparatus. The electronic system includes one or more batteries or other power sources, power management circuitry, one or more sensors, clock generation circuitry, control algorithms and circuitry, and lens driver circuitry. The lens driver circuitry includes one or more power sources, one or more high voltage generators and one or more switching circuits. Specifically, the lens driver comprises an H-bridge/H-bridge controller for providing the proper voltage, including polarity, to drive the electronic included in the ophthalmic apparatus.