Image Forming Apparatus Skew Detection via Dual Sensor Timing
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Solution Overview
Problem
Image forming apparatuses lack the capability to detect sheet skew and associate it with paper jams without additional sensors, leading to increased costs and ineffective prevention of paper jams.
Innovation Solution
The apparatus employs a first sensor and a second sensor positioned differently in the conveying path to detect passage times, calculating skew amounts and determining skew occurrence, with a cause estimating unit to identify the source of skew, thereby preventing paper jams without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensor is added for skew detection, then skew detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes existing paper detection sensors perform dual functions: detecting both paper jam occurrences and sheet skew. By analyzing passage timing data from sensors already positioned to detect paper jams, the system identifies skew conditions without requiring additional dedicated skew detection sensors, thereby achieving multi-functionality and avoiding increased device complexity
Solution Approach 2:
The system uses its own existing sensor network and passage timing measurement capabilities to detect skew, rather than relying on external or additional specialized sensors. The passage timing data, originally collected for paper jam detection, is repurposed to self-diagnose skew conditions, allowing the system to serve multiple detection needs with its current infrastructure
2Adaptability or versatility
If passage timing detection is used for both paper jam and skew detection, then measurement capability is improved, but detection precision for each function may deteriorate
Solution Approach 1:
The patent segments the analysis of passage timing data into distinct evaluation criteria: one set of thresholds and analysis methods for paper jam detection, and another set for skew detection. By dividing the detection logic and using different judgment criteria for each condition, the system maintains high precision for both functions simultaneously while using the same physical sensors
Solution Approach 2:
The system applies different detection thresholds and analysis methods tailored to each detection purpose (paper jam vs. skew) based on the local requirements of each function. The passage timing data is evaluated with function-specific criteria, ensuring that each detection task receives the appropriate level of sensitivity and threshold settings for its particular needs
Data Source
AI summary
An image forming apparatus according to the present invention includes: a first sensor that is provided in a conveying path for a sheet and detects a first passage time of the sheet; a second sensor that is provided in a position different from a position of the first sensor in both a conveying direction of the sheet and a direction orthogonal to the conveying direction, and detects a second passage time of the sheet; a skew determining unit that calculates a skew amount of the sheet from a difference between the first passage time detected by the first sensor and the second passage time detected by the second sensor and determines occurrence of skew of the sheet on the basis of the skew amount; and a cause estimating unit that estimates, when the skew determining unit determines that the skew occurs, a cause of the occurrence of the skew.