Media Conveyance Device with Periodic Optical Slack Detection
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Solution Overview
Problem
Existing media conveyance devices face challenges in accurately detecting media slack due to diffuse detection beams, leading to detection errors when the gap between emitters and photodetectors is small, which can result in excessive tension on the media and imprecise conveyance.
Innovation Solution
A media conveyance device with a detection mechanism featuring a first and second detector, where the first emitter and second emitter emit exclusively, preventing mistaking detection of one beam as another, allowing for accurate slack detection without precise alignment of optical axes, and enabling controlled spindle rotation based on signal outputs from multiple detectors to maintain desirable slack levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap between emitters and photodetectors is made small to improve detection precision, then measurement precision of media slack is improved, but detection errors occur due to diffuse light causing photodetectors to detect wrong beams
Solution Approach 1:
The emitters are driven to emit light alternately in a periodic manner rather than continuously. The first emitter emits light during its turn, then the second emitter emits light during its turn. This periodic emission pattern ensures that each photodetector only detects light from its corresponding emitter, eliminating cross-detection errors while maintaining small gap configuration for high precision slack detection
Solution Approach 2:
The detection system transitions from a static configuration where all emitters could potentially be detected simultaneously to a dynamic time-multiplexed system. The emission state of each emitter is controlled dynamically based on detection requirements, with the controller switching which emitter is active at any given moment to prevent beam confusion
2Measurement precision
If multiple emitters and photodetectors are used to improve detection coverage, then measurement precision is improved, but device complexity increases due to need for precise alignment and control
Solution Approach 1:
By implementing periodic emission control where emitters are activated sequentially rather than simultaneously, the system reduces the complexity of optical alignment requirements. The controller manages the emission timing of each emitter, ensuring that only one emitter is active at a time, which simplifies the detection mechanism while maintaining multi-point detection capability for precise slack measurement
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 ensures accurate detection and conveyance of media with desirable slack, preventing excessive tension and maintaining precise control over spindle rotation, thereby ensuring reliable and precise media conveyance.
Implementation Method 1
a first detector including a first emitter and first photodetector disposed vertically below the spindle, and outputting to the controller a signal based on the amount of light detected by the first photodetector; and a second detector including a second emitter disposed vertically below the first emitter and a second photodetector disposed vertically below the first photodetector
Data Source
AI summary
A control method of a media conveyance device enables accurately detecting media slack by a detection mechanism with multiple emitters and multiple photodetectors disposed opposite the emitters. A printer (media conveyance device) has a controller that controls a delivery mechanism, a conveyance mechanism that conveys media, a delivery mechanism, and a conveyance mechanism, and controls conveying roll paper; a first detector including a first emitter and first photodetector; and a second detector including a second emitter and second photodetector. When driving the conveyance mechanism, the controller selectively controls the first emitter and first photodetector to emit, and drives a spindle based on signal output from the first detector when first emitter emits, and signal output from the second detector when second emitter emits.