Sheet Conveyance Speed Control Using Dual Edge Detection
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Solution Overview
Problem
Existing sheet processing apparatuses face challenges in controlling conveyance speed accurately, leading to increased product volume and cost, especially when handling larger sheets, as they lack efficient detection and control mechanisms for maintaining consistent sheet speed during processing.
Innovation Solution
A sheet processing apparatus is designed with a conveying unit, multiple detecting devices to track the sheet's leading and rear edges, and a control unit that calculates the actual conveyance speed and adjusts the roller rotation to maintain a predetermined target speed, ensuring consistent sheet conveyance despite variations in sheet length and roller diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated detecting device is provided for detecting the conveyance speed of the sheet, then the conveyance speed can be detected accurately, but the product volume and cost increase
Solution Approach 1:
The patent applies multi-functionality by enabling existing detecting devices (originally used for position detection) to also serve conveyance speed detection. The first and second detecting devices, initially positioned to detect sheet presence, are repurposed to calculate conveyance speed by measuring the time interval for the sheet to travel between them, eliminating the need for a dedicated speed detection device
Solution Approach 2:
The patent introduces time as an intermediary parameter to indirect measurement of conveyance speed. Instead of directly measuring speed, the system measures the time it takes for the sheet to travel between two known positions (detecting devices), then calculates speed from this time interval and the known distance, avoiding direct speed sensing hardware
2Productivity
If the sheet size is increased, then the processing capacity is improved, but the conveyance speed control becomes more difficult
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual conveyance speed through the detecting devices and comparing it with the target speed. The control unit adjusts the roller rotation speed based on the calculated actual speed, creating a closed-loop system that maintains precise conveyance control even for larger sheets with varying inertia and friction characteristics
Data Source
AI summary
A sheet processing apparatus comprising: a conveying unit configured to have a roller that conveys a sheet in a conveyance direction; a first detecting device disposed downstream of the conveying unit in the conveyance direction; a second detecting device disposed downstream of the first detecting device in the conveyance direction; a boring unit configured to have a punch that performs boring in the sheet; and a control unit is used. The first detecting device and the second detecting device each detect passage of a leading edge of the sheet being conveyed. The control unit calculates an actual conveyance speed of the sheet on the basis of detection results of the first detecting device and the second detecting device, and controls rotation of the roller, on the basis of the actual conveyance speed, so that the sheet is conveyed at a predetermined target speed.