Position Detection Sensor Using Asymmetric Pixel Groups
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Solution Overview
Problem
Current position detection sensors face challenges in detecting a two-dimensional position of a light spot with high speed and accuracy, especially when the spot diameter is small, due to limitations in pixel count and linearity of signal intensity differences.
Innovation Solution
A position detection sensor is designed with a configuration of first and second pixel pair groups, where each pair includes multiple pixel parts generating electric signals based on incident light, with integrated signal values used to calculate positions, allowing for faster detection and reduced bias in signal intensity across pixel parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a four-division photodiode is used to reduce the number of electric signals read out, then detection speed is improved, but measurement precision deteriorates when spot diameter is small
Solution Approach 1:
The photodiode surface is divided into multiple pixel groups (first pixel group, second pixel group, third pixel group, fourth pixel group) arranged in different directions. Each pixel group contains multiple pixel parts that can independently detect light, allowing the system to maintain high detection speed while improving precision for small spot diameters through multi-point detection and signal integration.
2Measurement precision
If the number of pixels is increased to improve position detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The pixel groups are arranged asymmetrically in different directions (first direction, second direction, third direction, fourth direction) rather than uniform distribution. This asymmetric arrangement allows the sensor to capture light spot position information from multiple angular perspectives, improving detection accuracy while maintaining a relatively simple overall structure that can be integrated on a single chip.
3Measurement precision
If pixel parts are made smaller to detect smaller light spots, then measurement precision is improved, but detection speed deteriorates due to signal intensity reduction
Solution Approach 1:
Multiple pixel parts from different pixel groups are merged in their detection functions through signal integration. The calculation unit combines electric signals from corresponding pixel parts across different groups (first, second, third, and fourth pixel groups) to generate the final position detection result. This merging approach amplifies the weak signals from small pixel parts while maintaining the ability to detect small light spot diameters, thus preserving both precision and speed.
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
Enables accurate and high-speed detection of two-dimensional positions even with small light spot diameters by adjusting pixel part size and arrangement, suppressing signal bias and improving detection speed compared to existing technologies.
Implementation Method 1
a first pixel part that generates a first electric signal corresponding to an incident light amount of the light and a second pixel part that is disposed side by side with the first pixel part in the first direction and generates a second electric signal corresponding to an incident light amount of the light
Data Source
AI summary
Provided is a position detection sensor. In a first pixel part, as an incident position is closer to a first end of a first pixel pair group in a second direction, an intensity of a first electric signal decreases. In a second pixel part, as the incident position is closer to the first end, an intensity of a second electric signal increases. In a third pixel part, as the incident position is closer to a second end of a second pixel pair group in a first direction, an intensity of a third electric signal decreases. In a fourth pixel part, as the incident position is closer to the second end, an intensity of a fourth electric signal increases. A calculation unit calculates a second position on the basis of the first and second electric signals, and calculates a first position on the basis of the third and fourth electric signals.