Sheet Feeder Optical Height Detection for Thick Small Sheets
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Solution Overview
Problem
Existing sheet feeding apparatuses face challenges in feeding small, thick sheets due to mechanical contact issues with height detection sensors and air separation mechanisms, leading to instability and control problems.
Innovation Solution
A reflection-type sensor is used to detect the upper limit position of sheets, eliminating mechanical contact and allowing for easier floating of small-sized sheets, combined with a side surface regulating member and adjustable air flow for separation, enhancing control and accommodating various sheet sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical height detection sensor lever is used to detect sheet position, then the sheet feeding apparatus can detect and control sheet height, but small and thick sheets cannot be properly floated and separated due to mechanical contact issues
Solution Approach 1:
The patent replaces the mechanical height detection sensor lever with a reflection-type optical sensor that detects sheet presence by receiving reflected light from the sheet surface. This eliminates mechanical contact that prevented small and thick sheets from floating properly, while maintaining accurate height detection capability through optical measurement.
Solution Approach 2:
The patent introduces a light reflecting surface (the sheet itself) as an intermediary between the optical sensor and the detection system. The reflection-type sensor detects sheet position by receiving light reflected from the sheet surface, enabling non-contact measurement that accommodates various sheet types including small and thick sheets.
2Ease of operation
If air blowing is used to separate and float sheets, then sheet separation is improved, but control over sheet position becomes difficult and apparatus complexity increases
Solution Approach 1:
The patent applies air blowing locally at the sheet separation point (leading edge) rather than throughout the entire sheet feeding path. The air blowing unit is positioned to blow air at the leading edge of sheets to facilitate separation, while the optical sensor independently controls sheet position detection, dividing functions to reduce overall system complexity.
Solution Approach 2:
The patent segments the sheet feeding function into distinct components: air blowing for separation at the leading edge, and optical detection for position control. This functional segmentation allows each component to perform its specific task efficiently without interfering with the other, simplifying overall control.
3Volume of stationary object
If the distance between the pressing point and air blowing duct is reduced for small sheets, then compactness is improved, but sheet floating becomes more difficult
Solution Approach 1:
The patent replaces mechanical pressing with optical detection to determine sheet position. The reflection-type sensor detects sheet presence optically, eliminating the need for mechanical contact points. This allows the air blowing duct to be positioned closer to the sheet leading edge for compactness while the optical sensor independently manages floating control through non-contact detection.
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
This configuration enables stable feeding of small and thick sheets by maintaining the sheets in a floating state, improving control over the sheet position and maintaining the compactness of the image forming apparatus.
Implementation Method 1
it is constructed so that whether or not sheets P have reached an upper limit position is detected by a reflection type sensor
Implementation Method 2
the sheet separating section blows air at the edge parts of the sheets thereby making the sheet float up and separate
Implementation Method 3
a sheet feeding section that feeds one sheet at a time from the sheets inside that sheet storing section by sucking and holding the sheet on a suction belt using negative pressure
Data Source
Figure 1
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AI summary
A sheet feeder comprising a sheet receiving section (P20) having an elevating/lowering plate (960), a member (920) for regulating the sides of sheets, an air blowing section (986) for blowing air toward the sides of sheets at upper levels out of the sheets received in the sheet receiving section, a sheet suction-conveyance section (VT20) installed above the sheet receiving section with a gap kept from the uppermost sheet of the sheets received in the sheet receiving section, a reflective sensor (970) for detecting the upper limit position of stacked sheets received in the sheet receiving section, and a control section for performing control to elevate the elevating/lowering plate when an output from the reflective sensor indicates an intermediate state provided between a sheet brought into a floating state by an air flow which is blown from the air blowing section, and a sheet maintaining the stacked state. As a result, stabilized sheet-feeding can be ensured even if a thick sheet of a small size is used, and the upper limit position of sheets can be controlled by a simple constitution.