Coordinate Input Apparatus Multi-System Conversion
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Solution Overview
Problem
Existing coordinate input apparatuses suffer from errors in detecting touch positions due to quantization errors, measurement errors, and shifting of components, leading to inaccuracies in calculated coordinates, especially when the angles detected by light-receiving devices contain errors, causing misalignment and incorrect input positions.
Innovation Solution
A coordinate input apparatus that uses a light projector and multiple light receptors to set up two coordinate systems, converting detected coordinate values from one system to another to improve accuracy, with a configuration of sensor units and operation control circuits to optimize light detection and calculate precise touch positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If light-receiving devices detect light in units of pixels for coordinate input, then the apparatus can detect touch positions, but quantization errors arise leading to coordinate detection inaccuracies
Solution Approach 1:
The patent divides the coordinate input surface into multiple coordinate systems, each detected by different combinations of light-receiving devices. By segmenting the detection task across multiple coordinate systems and combining their results, the system reduces quantization errors that would occur if a single coordinate system were used alone.
Solution Approach 2:
The patent introduces a second coordinate system as an additional dimension of detection. Instead of relying on a single coordinate system with pixel-based quantization errors, the system establishes multiple coordinate systems and converts between them, adding a dimensional layer to the detection process that enables error reduction through coordinate transformation and averaging.
2Productivity
If table lookup or polynomial approximation is used to convert pixel numbers to angle values, then coordinate calculation can be performed, but conversion errors occur reducing accuracy
Solution Approach 1:
The patent implements a feedback mechanism where coordinate values are detected in multiple coordinate systems, converted between systems, and compared. The system uses the results from different coordinate systems to validate and refine the final coordinate determination, creating a feedback loop that reduces conversion errors while maintaining calculation efficiency.
Solution Approach 2:
The patent changes the parameters of the coordinate system itself by establishing multiple coordinate systems with different orientations and transformations. Instead of relying solely on pixel-to-angle conversion within a single system, the system transforms coordinates between multiple systems, changing the mathematical parameters involved and thereby reducing systematic conversion errors.
3Ease of manufacture
If the apparatus is anchored to housing with recorded reference angles, then coordinate calculation can be performed, but measurement errors and placement position shifts occur over time
Solution Approach 1:
The patent transitions from a static reference angle system to a dynamic multi-coordinate system. Instead of relying on fixed reference angles recorded during assembly that may become inaccurate due to placement shifts, the system dynamically establishes multiple coordinate systems that can adapt to positional changes, reducing the impact of manufacturing and assembly errors on long-term reliability.
4Measurement precision
If pixel resolution of light-receiving device is increased to reduce quantization error, then coordinate accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent segments the high-precision detection task across multiple standard-resolution light-receiving devices operating in different coordinate systems. Instead of using a single high-resolution device, the system divides the detection function across multiple devices, achieving equivalent or superior accuracy through coordinate transformation and data fusion while avoiding the complexity and cost of high-resolution hardware.
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 significantly reduces errors in coordinate detection, ensuring accurate input positions by optimizing light detection and conversion processes, thereby enhancing the precision of touch input on coordinate input surfaces.
Implementation Method 1
A system in which a retroreflective material is provided on an outer side of a coordinate input surface, light from a light projector is reflected by the retroreflective material, and a light amount distribution thereof is detected by a light receptor
Data Source
AI summary
A coordinate input apparatus detects a specified position in a coordinate-input effective area using a light projector that projects light onto a coordinate input surface and a plurality of light receptors that receive the light projected by the light projector. The coordinate input apparatus sets a first coordinate system based on a positional relationship between two light receptors constituting a first combination of the plurality of light receptors and a second coordinate system based on a positional relationship between two light receptors constituting a second combination that is different from the first combination, and converts a coordinate value of the specified position detected using the second coordinate system into a coordinate value in the first coordinate system.