Sheet Size Detection Device with Concavo-Convex Lever Patterns
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Solution Overview
Problem
Existing sheet size detection devices in image forming apparatuses are prone to erroneous detection due to operator errors, limited detectable sheet sizes, and increased costs from multiple sensors, leading to paper jams, premature wear of process cartridges, and reduced productivity.
Innovation Solution
A sheet size detection device with a sheet width direction regulating member, a sheet conveyance direction regulating member, two levers with concavo-convex patterns, and a pattern supplementing device that prevents erroneous detection by adjusting the concavo-convex patterns to account for positional displacement and enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the distance between adjacent convex portions of the concavo-convex pattern is increased to prevent erroneous detection, then detection accuracy is improved, but the number of detectable sheet sizes is reduced
Solution Approach 1:
The detection system is divided into multiple independent levers (first lever, second lever, third lever), each with its own concavo-convex pattern. This segmentation allows each lever to detect specific sheet size ranges independently, and the combined information from all levers enables comprehensive detection of multiple sheet sizes while maintaining adequate convex portion spacing for accuracy
Solution Approach 2:
The detection system transitions from a single-dimensional detection approach to a multi-dimensional approach by using multiple levers arranged in different orientations and positions. The first lever detects along one dimension, the second lever along another dimension, and the third lever supplements detection in a third dimension, enabling comprehensive multi-size detection without reducing spacing between convex portions
2Measurement precision
If multiple sensors are provided to precisely detect sheet sizes in both sheet conveyance direction and sheet width direction, then detection accuracy is improved, but device complexity and cost are increased
Solution Approach 1:
Multiple detection functions are merged into a single integrated lever system. The first lever, second lever, and third lever work together as a unified mechanism where the combined concavo-convex patterns of all levers interact with a single sensor to detect both sheet conveyance direction and sheet width direction dimensions simultaneously
Solution Approach 2:
Each lever serves multiple functions: the first lever detects sheet size in the conveyance direction, the second lever detects sheet size in the width direction, and the third lever supplements detection for specific size ranges. This multi-functionality allows a single lever-based mechanism to replace what would traditionally require multiple separate sensors
3Adaptability or versatility
If the concavo-convex pattern is made more minute to recognize diversified sheet sizes, then the number of detectable sheet sizes is improved, but positional displacement causes erroneous recognition
Solution Approach 1:
Different regions of the lever system have different concavo-convex pattern characteristics optimized for their specific detection purposes. The first lever has patterns optimized for conveyance direction detection, the second lever has patterns optimized for width direction detection, and the third lever has patterns specifically designed to prevent erroneous detection in critical areas, creating local quality variations that enhance overall reliability
Data Source
AI summary
An image forming apparatus includes a sheet size detection device including a sheet width direction regulating member, a sheet conveyance direction regulating member, two levers, a detection sensor, and a pattern supplementing device. The levers each have a concavo-convex pattern and interlock with the regulating members, respectively, and are superimposed to have the same center of rotation and the same locus formed by a leading end of the concavo-convex pattern. The concavo-convex pattern of at least one of the levers is shaped to prevent, in a detection pattern, erroneous detection attributed to positional displacement of the concavo-convex pattern. The detection sensor including push switches detects the sheet size according to a combined concavo-convex pattern formed by the superimposed levers. The pattern supplementing device supplements the concavo-convex pattern of the at least one lever to prevent, in another detection pattern, erroneous detection attributed to the shaping of the concavo-convex pattern.