Sheet Detecting Device Integrating Flag and Reflection Sensors
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Solution Overview
Problem
Conventional sheet detecting devices in image forming apparatuses face challenges in accurately detecting sheets of various types, particularly with transparent media, and are hindered by size and power consumption constraints due to the use of multiple optical sensors.
Innovation Solution
A sheet detecting device utilizing a common light emitter and both flag-type and flag-less optical sensors, where the flag-type sensor detects by blocking light and the flag-less sensor by light reflection, with a movable flag and reflective member to optimize detection and reduce size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a combination of flag-type optical sensor and flag-less optical sensor is used to detect sheets of various types, then detection accuracy is improved, but device size and power consumption increase
Solution Approach 1:
The patent combines a flag-type optical sensor and a flag-less optical sensor into a single integrated detection device. The flag sensor detects transparent sheets through flag rotation, while the flag-less sensor detects opaque sheets through light reflection, enabling accurate detection of all sheet types within one compact unit rather than requiring separate devices.
Solution Approach 2:
The detection device is designed to handle multiple detection functions within a single system. It can detect both transparent and opaque sheets using two different detection methods (flag rotation and light reflection), making it universally applicable to various sheet types without requiring separate specialized sensors.
2Measurement precision
If a combination of flag-type optical sensor and flag-less optical sensor is used to detect sheets of various types, then detection accuracy is improved, but power consumption increases
Solution Approach 1:
The light source in the detection device operates periodically rather than continuously. The controller activates the light source only when sheet detection is required, and deactivates it when not needed, thereby reducing overall power consumption while maintaining accurate detection capability when sheets need to be detected.
Solution Approach 2:
By integrating both flag-type and flag-less sensors into a single device with a shared light source and controller, the patent reduces redundant power consumption that would occur if two separate detection devices were used. The shared components eliminate duplicate power requirements.
3Measurement precision
If flag returns from detection position to standby position, then transparent sheet detection is achieved, but response time increases when sheet interval is small
Solution Approach 1:
The patent introduces a flag as an intermediary mechanical element that translates sheet contact into detectable positional changes. When a transparent sheet passes through, it causes the flag to rotate, which in turn changes the optical path for the light sensor, enabling detection without requiring the flag to fully return to its original position before the next detection cycle.
Solution Approach 2:
The patent replaces a purely mechanical flag return mechanism with an optical detection system. Instead of waiting for the flag to mechanically return to its standby position, the system uses light sensors to detect the flag's intermediate positions, significantly reducing the response time for consecutive sheet detection.
4Speed
If ordinary optical sensor is used for detection, then response time is improved, but detection of transparent paper fails
Solution Approach 1:
The patent applies different detection methods to different sheet types based on their local properties. Opaque sheets are detected using light reflection principles with the flag-less sensor, while transparent sheets are detected using flag rotation principles with the flag sensor, optimizing detection accuracy for each specific sheet type's characteristics.
Solution Approach 2:
The detection system uses a composite approach combining two different sensing mechanisms (flag-type and flag-less optical sensors) in one device. This composite structure allows the system to leverage the strengths of each sensor type - the fast response of the flag-less sensor for opaque sheets and the effective transparent sheet detection of the flag sensor.
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
Enables accurate detection of sheets regardless of type, while minimizing size and power consumption by integrating sensors and using a reflective member to enhance light detection efficiency.
Implementation Method 1
an optical sensor which does not employ a flag, to detect the presence or absence of a sheet of recording medium... when a sheet is present, the light emitted from its light emitting portion is blocked or reflected by the sheet
Implementation Method 2
an optical sensor which does not employ a flag... the light emitted from its light emitting portion is blocked or reflected by the sheet
Data Source
AI summary
A sheet detecting device usable with a sheet feeding device for feeding a sheet, the sheet detecting device includes a common light emitter; a first light receptor and a second light receptor for receiving the light emitted by the common light emitter and output a signal in response to the reception of the light; a first detector configured to detect presence or absence of the sheet by switching the signal outputted by light receptor, in response to the sheet blocking or reflecting the light emitted by the common light emitter; a movable portion capable of being moved by the sheet which is moving; and a second detector configured to detect presence or absence of the sheet by switching the signal outputted by the second light receptor, in response to the movable portion forming or blocking a optical path for the light emitted by the common light emitter.