Backplane for Eye-Mounted Display with Variable Pixel Resolution
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Solution Overview
Problem
Eye-mounted displays, such as femtoprojectors in contact lenses, face challenges in matching the high resolution and dynamic range of the human eye while minimizing power consumption and data bandwidth, due to their small size and additive nature in augmented reality applications.
Innovation Solution
The use of a backplane and frontplane system with variable hardware pixel resolutions, pulse width modulation (PWM) and pulse amplitude modulation (PAM) for efficient data transmission, and subframe-based image processing to reduce data rate and power consumption, allowing dynamic resolution matching and efficient tiling on the retina.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the backplane chip size is reduced to minimize obstruction in the contact lens, then the lens obstruction is reduced, but the ability to provide high resolution and high dynamic range image projection is compromised
Solution Approach 1:
The patent divides the contact lens into distinct functional regions: a first region containing the backplane chip and a second region containing the light emitter array. This spatial segmentation allows the backplane chip to be compact while the light emitter array can be expanded to provide high resolution image projection, resolving the contradiction between small chip size and high image quality.
2Area of stationary object
If the backplane chip size is reduced to minimize obstruction in the contact lens, then the lens obstruction is reduced, but the power consumption capability is compromised
Solution Approach 1:
By separating the backplane chip from the light emitter array into different regions, the patent allows the light emitter array to be positioned where it can access sufficient power while the backplane chip remains small. The segmented architecture enables independent optimization of power delivery infrastructure without increasing the backplane chip area, thus resolving the contradiction between small chip size and adequate power consumption capability.
3Loss of information
If variable hardware pixel resolutions are implemented to match human eye resolution, then data bandwidth is reduced, but the device complexity increases
Solution Approach 1:
The patent implements variable hardware pixel resolutions where different regions of the light emitter array have different resolution characteristics matching the human eye's foveal vision properties. This local quality approach allows high resolution only where needed (central vision) and lower resolution in peripheral regions, reducing overall data bandwidth requirements while managing device complexity through region-specific optimization rather than uniform high resolution across the entire array.
Data Source
AI summary
An eye-mounted display includes a femtoprojector, which includes a backplane and a frontplane. The backplane receives data (e.g., data packets) that specify the image to be projected by the eye-mounted display. It converts this data to drive signals (e.g., current) to drive the frontplane. The frontplane contains an array of light emitters (e.g., LEDs) that produce light according to the drive signals, thus generating the desired image. In one approach, the image is deconstructed and transmitted to the backplane as needed as microframes which are displayed asynchronously and only for regions where the image has changed, rather than continuously scanning full picture frames at the full frame rate. In another aspect, the femtoprojector has variable pitch between adjacent light emitters.