Projection Lens Backlash Detection Using Positioning Signals
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Solution Overview
Problem
Existing gear systems, particularly in projection apparatuses, face challenges in accurately detecting and calibrating backlash due to variations in gear pitch and tooth thickness, leading to inaccurate movement control and potential issues like blurred images, as existing methods require additional precision measurement instruments and cannot account for backlash changes over time or with wear.
Innovation Solution
A backlash detecting system comprising a projection apparatus with a motor module, positioning module, and controller, where a transmission gear meshes with the gear structure, and a positioning piece with blocking pieces generates a positioning signal, allowing the controller to calculate backlash in real-time and adjust for different rotation directions without additional measurement instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precision measurement instruments are used to calibrate backlash, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The system uses the existing gear structure and positioning piece within the projection apparatus itself to detect backlash, eliminating the need for external precision measurement instruments. The positioning piece generates positioning signals that directly reflect backlash conditions, allowing the system to self-diagnose and calibrate without additional complex equipment.
Solution Approach 2:
The patent replaces mechanical precision measurement instruments with an electronic sensing system. The positioning piece with blocking pieces generates electrical positioning signals that are processed by the control unit to calculate backlash, substituting mechanical measurement with electronic detection and signal processing.
2Manufacturing precision
If backlash is calculated based on gear pitch and tooth thickness, then manufacturing precision is improved, but adaptability to wear and rotation direction changes deteriorates
Solution Approach 1:
The system dynamically detects backlash during actual operation rather than relying on static manufacturing parameters. The positioning piece continuously generates positioning signals that reflect real-time backlash conditions, allowing the system to adapt to wear, temperature changes, and rotation direction variations that occur during use.
Solution Approach 2:
The control unit receives positioning signals from the positioning piece and uses this feedback to calculate and compensate for backlash in real-time. This closed-loop feedback mechanism allows the system to continuously monitor and adjust for backlash changes due to wear or operational conditions, maintaining accuracy throughout the gear's service life.
3Measurement precision
If additional measuring procedures are added during manufacturing, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The backlash detection function is merged with the existing positioning mechanism of the projection apparatus. The positioning piece that already exists for lens positioning is also used to generate positioning signals for backlash detection, combining two functions into one component and eliminating separate measurement procedures.
Solution Approach 2:
The system performs backlash detection using its own internal components during normal operation, eliminating the need for separate factory calibration procedures. The positioning piece and control unit work together to automatically calculate backlash without requiring external measurement instruments or additional manufacturing steps.
4Reliability
If gear clearance is increased to prevent jamming, then reliability is improved, but positioning precision deteriorates
Solution Approach 1:
The control unit uses positioning signals from the positioning piece to detect and compensate for backlash in real-time, allowing the system to maintain positioning precision despite the necessary gear clearance. The feedback mechanism calculates the actual backlash and adjusts control commands to offset its effect, preserving both reliability and precision.
Data Source
AI summary
A projection apparatus is provided. A gear structure and a positioning piece in the projection lens module are disposed about opposite sides outside the lens barrel. The gear structure and the positioning piece rotates around an optical axis of the lens barrel acting as a rotating axis. Moreover, when the gear structure rotates, the positioning piece rotates relative to the gear structure. A transmission gear of the motor module meshes with the gear structure to drive the gear structure to rotate. The positioning module is disposed next to the positioning piece and is configured for measuring rotation of the positioning piece to generate a positioning signal. The controller controls the motor module to drive the transmission gear, receives the positioning signal, and calculates a backlash between the transmission gear and the gear structure according to the positioning signal. A backlash detecting system and a method thereof are provided.