Movable Lens Position Detection Using Dual Sensor Speeds
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Solution Overview
Problem
Existing position detection devices for movable lenses in imaging apparatuses face challenges in achieving high resolution and accuracy while maintaining miniaturization and reducing manufacturing costs, as they often require high-accuracy sensors with larger operation ranges and increased costs due to the need for precise magnetization pitches or low-error potentiometers.
Innovation Solution
A position detection device utilizing a first detection sensor that outputs a continuously increasing or decreasing signal for absolute position detection and a second detection sensor that outputs a periodically changing signal for relative position detection, operating at different speeds, with the second sensor's signal period matching or exceeding the first sensor's detection error, allowing for adjustable sensitivity and simplified operation within a shared range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnetization pitch of the MR sensor is enlarged to match the periodic signal with the detection error of the first sensor, then high resolution and high accuracy position detection is achieved, but the operation range of the second detection sensor increases causing miniaturization to fail and cost to increase
Solution Approach 1:
The patent applies dynamics by making the operation speed of the second detection sensor variable rather than constant. The control unit adjusts the operation speed dynamically so that one period of the periodic signal corresponds to the detection error range of the first sensor, enabling accurate position detection within a limited range while preventing the sensor from operating over its full range, thus achieving miniaturization
Solution Approach 2:
The patent changes the operation speed parameter of the second detection sensor to optimize performance. By adjusting the operation speed so that the periodic signal period matches the first sensor's detection error, the system achieves high accuracy without requiring a large magnetization pitch, thereby reducing the sensor size and cost
2Measurement precision
If a potentiometer with small linearity error and small hysteresis is used as the first detection sensor to achieve high accuracy and match the periodic signal, then position detection accuracy is improved, but the manufacturing cost increases
Solution Approach 1:
The patent changes the operation speed parameter of the second detection sensor to compensate for the lower accuracy of the first sensor. By adjusting the speed ratio between the two sensors, the periodic signal's one period is made to correspond to the detection error of the first sensor, enabling high overall accuracy without requiring an expensive high-precision potentiometer
Solution Approach 2:
The second detection sensor acts as an intermediary that provides high-precision periodic signal reference. This periodic signal is used to correct and enhance the position detection accuracy of the first sensor, allowing the system to achieve high precision without relying on an expensive high-accuracy first sensor
3Measurement precision
If the operation speed of the second detection sensor is increased to improve detection resolution, then measurement precision is improved, but the operation range increases causing miniaturization to fail
Solution Approach 1:
The patent applies dynamics by making the operation speed of the second detection sensor variable. The control unit adjusts the speed dynamically so that the sensor operates at optimal resolution within a limited range, preventing the operation range from expanding while maintaining high detection resolution through speed optimization
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 high-resolution and high-accuracy detection of movable lens positions while achieving miniaturization and reducing manufacturing costs by optimizing sensor operation speeds and ranges, eliminating the need for high-cost, high-accuracy sensors and large magnetization pitches.
Implementation Method 1
a first detection sensor that operates in a predetermined direction, outputs a continuously increasing or decreasing signal, and detects an absolute position of a movable lens moved in an optical axis direction
Implementation Method 2
a second detection sensor that operates in the predetermined direction, outputs a periodically and continuously changing signal, and detects a relative position of the movable lens
Data Source
AI summary
There is provided a position detection device including a first detection sensor that operates in a predetermined direction, outputs a continuously increasing or decreasing signal, and detects an absolute position of a movable lens moved in an optical axis direction, and a second detection sensor that operates in the predetermined direction, outputs a periodically and continuously changing signal, and detects a relative position of the movable lens. The first detection sensor and the second detection sensor operate at different operation speeds.