Barrel Driving Backlash Correction via Photo-Interrupter Feedback
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Solution Overview
Problem
The existing barrel driving system for zooming and focusing operations experiences backlash errors due to the non-tight fit between guiding protrusions and grooves, leading to inaccuracies in position detection and movement, which degrade the precision of zooming and focusing operations over time.
Innovation Solution
A barrel driving system with a driving module, position detection units, registers, and a processing unit that uses a lookup table to correct backlash by replacing initial count values with predetermined values based on detection signals from the second position detection unit, ensuring accurate positioning and movement correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the guiding protrusion and guiding groove are designed with no tight fit for smooth movement, then the ease of operation is improved, but backlash occurs causing measurement precision to deteriorate
Solution Approach 1:
The system performs preliminary action by detecting the direction of barrel movement (clockwise or counterclockwise rotation of driving barrel) before the backlash correction is needed. The control unit stores direction information in advance, and when backlash is detected through the home PI signal, the pre-stored direction information is used to determine the correct correction amount, enabling rapid compensation without waiting for position recalculation.
Solution Approach 2:
The system implements feedback by using the home PI (photo-interrupter) to detect when the focusing barrel triggers during zooming operations. This feedback signal indicates the presence of backlash, and the control unit responds by adjusting the count value stored in the first register based on the detected backlash amount and pre-stored direction information, thereby correcting the position detection accuracy through continuous feedback loops.
2Device complexity
If backlash is not corrected, then the device complexity remains low, but manufacturing precision deteriorates due to accumulated errors in zooming and focusing operations
Solution Approach 1:
The control unit performs multiple functions using a single integrated approach: it stores direction information from driving barrel rotation, detects backlash through home PI signals, calculates correction amounts based on stored backlash data, and adjusts count values in the first register. This multi-functional design achieves high manufacturing precision without adding separate dedicated components for each function, thereby maintaining relatively low device complexity while improving zooming and focusing accuracy.
Solution Approach 2:
The control unit acts as an intermediary between the driving barrel motor and the position detection system. It receives direction information from the driving barrel rotation, processes home PI feedback signals to detect backlash, and mediates the correction by adjusting the count value in the first register before this information is used for position calculation, thereby eliminating accumulated errors in zooming and focusing operations.
3Measurement precision
If the home PI is used to detect backlash during zooming operations, then the measurement precision is improved, but the device complexity increases due to additional position detection requirements
Solution Approach 1:
The home PI is designed to serve multiple functions: it detects the initial position of the focusing barrel, monitors backlash during zooming operations by detecting when the focusing barrel triggers during motor-driven zooming, and provides feedback signals for correction calculations. By making the home PI multi-functional, the system achieves high measurement precision for backlash detection without adding separate dedicated sensors or detection mechanisms, thereby limiting the increase in device complexity.
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 effectively corrects backlash errors, enhancing the accuracy of zooming and focusing operations by aligning the actual position with the intended count values, thereby maintaining precise control over the barrel movements.
Implementation Method 1
a first position detection unit (21), which detects the driving module (13, 14, 15) and outputs a first detection signal (211)
Implementation Method 2
a second position detection unit (22), which is triggered by the focusing barrel (12) and outputs a second detection signal (221)
Data Source
AI summary
The patent discloses a lens barrel driving system and a backlash correction method thereof. In such system, a zoom photo-interrupter (PI) is used to detect the movement of a zooming barrel and generate a first count value. The movement of a focusing barrel corresponds to the movement of the zooming barrel, so that when the zooming barrel is driven to move from an initial position to a first zooming position or from the first zoom position to a second zoom position, the focusing barrel moves correspondingly and its movement triggers a home PI to generate a second count value. Upon the generation of the second count value, a predetermined value is used to replace the first count value so as to correct the error caused by backlash of lens barrels.