Series Photodiode Reset Input for Selective Light Blocking
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Solution Overview
Problem
Existing devices require reliable and low-power input elements, particularly for hardware reset functions that operate independently of software, as they need to function without software interference and be resistant to non-responsive states.
Innovation Solution
A device with a user-operatable input element comprising a sensing circuit with a first and second photodiode arranged in series, where the photodiodes are spaced apart to receive ambient light through separate areas of the housing, allowing the user to block light and detect changes in conductance to indicate input operation, with a low-pass filter to prevent accidental activation, and a control unit for resetting the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single photodiode is used as an input element, then the device complexity is reduced, but the reliability of input detection is insufficient
Solution Approach 1:
The sensing circuit is segmented into two separate photodiodes (first and second photodiodes) arranged in series, each receiving light through separate areas of the housing. This segmentation allows independent detection of light blocking events, improving reliability while maintaining circuit simplicity through the series configuration.
2Ease of operation
If photodiodes are arranged close together, then the device size is reduced, but the user cannot selectively block light from one photodiode
Solution Approach 1:
The housing is designed with separate local areas (first area and second area) for each photodiode, allowing the user to selectively block light to one photodiode while leaving the other exposed. This local differentiation enables selective operation without requiring large device volume.
3Reliability
If the housing is made opaque to prevent water ingress, then waterproofing is improved, but ambient light cannot reach the photodiodes
Solution Approach 1:
The housing is designed with localized transparent or light-permeable areas at specific positions to allow light transmission to the photodiodes, while the rest of the housing remains opaque for waterproofing. This local differentiation maintains both waterproofing reliability and light transmission capability.
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
This design provides a low-cost, waterproof, and low-power input element that can function as a hardware reset switch without software support, utilizing ambient light for operation and minimizing power consumption while ensuring reliable detection of user input.
Implementation Method 1
A sensing circuit comprising at least one first photodiode and at least one second photodiode... both arranged to receive ambient light through the housing
Data Source
AI summary
The device has an input element, which can be used for resetting the device. The input element has at least one first photodiode arranged in series to at least one second photodiode. A voltage is applied over the photodiodes. When the user blocks light to only the second photodiode, the voltage at the interconnection between the photodiodes changes, which can be used to trigger the input element. The input element has low power consumption and high reliability.