Sheet Measuring Device Speed Differential Roller Tension Control

Solution Overview

Problem

Existing image measuring devices for electrophotographic systems face challenges in achieving high measurement accuracy due to the need for complex and costly mechanisms to maintain a stable distance between the color sensor and the sheet, such as the use of a pressing roller and moving mechanisms.

Innovation Solution

A measuring device comprising a first roller pair, a colorimetric unit, a second roller pair with a higher peripheral speed, and a third roller pair, along with a torque limiter, which allows the first roller pair to maintain a stable peripheral speed while the third roller pair accelerates after the sheet passes, ensuring consistent tension and improved measurement accuracy without the need for additional pressing mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a pressing roller and moving mechanism are used to maintain stable distance between color sensor and sheet, then measurement accuracy is improved, but device complexity and cost increase

Engineering Contradiction:

Improvecolor measurement accuracyVSAvoiddevice structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention removes the pressing roller and its moving mechanism from the system. Instead of using a complex mechanical pressing system, the patent uses a simplified roller pair configuration where the second roller pair rotates at a higher peripheral speed to create tension that naturally maintains stable sheet positioning during measurement, eliminating unnecessary components while achieving the same measurement stability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical pressing system with a speed-differential roller system. By making the second roller pair rotate at a higher peripheral speed than the first roller pair, the system uses rotational speed difference to create controlled tension and maintain stable sheet positioning, substituting complex mechanical pressing mechanisms with a simpler speed-controlled rotational system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a pressing roller and moving mechanism are used to maintain stable distance between color sensor and sheet, then measurement accuracy is improved, but device cost increases

Engineering Contradiction:

Improvecolor measurement accuracyVSAvoiddevice cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The invention removes the pressing roller and its moving mechanism from the system. Instead of using a complex mechanical pressing system, the patent uses a simplified roller pair configuration where the second roller pair rotates at a higher peripheral speed to create tension that naturally maintains stable sheet positioning during measurement, eliminating unnecessary components while achieving the same measurement stability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical pressing system with a speed-differential roller system. By making the second roller pair rotate at a higher peripheral speed than the first roller pair, the system uses rotational speed difference to create controlled tension and maintain stable sheet positioning, substituting complex mechanical pressing mechanisms with a simpler speed-controlled rotational system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If third roller pair is driven at higher speed after sheet passes, then sheet tension is maintained for accurate measurement, but speed synchronization becomes complex

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidroller speed coordination

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The invention uses dynamic speed adjustment where the third roller pair changes its rotational speed based on the sheet's position. Before the sheet passes, all roller pairs rotate at the same speed for synchronized feeding. After the sheet passes the measurement point, the third roller pair increases its speed to maintain tension. This dynamic speed change is controlled to occur at different timing for different roller pairs, creating a coordinated acceleration pattern that maintains measurement accuracy while managing speed synchronization.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention prepares the roller speed coordination in advance by setting the control timing so that the third roller pair's speed increase occurs after the sheet has passed the measurement point. This preliminary planning of speed coordination timing ensures that when the sheet is being measured, all rollers are synchronized, and the speed adjustment happens only after measurement is complete, avoiding complexity during the critical measurement phase.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11501124B2Measuring device, image reading apparatus and image forming system for controlling movement of a sheet

Publication Date: 2022.11.15 CANON KK

AI summary

A measuring device includes a first roller pair, a colorimetric unit, a second roller pair, a third roller pair, a motor, and a torque limiter. The third roller pair is driven at a first speed before a trailing end of the sheet with respect to a sheet feeding direction passes through the first roller pair and is driven at a second speed higher than the first speed after the trailing end of the sheet passes through the first roller pair. The first speed is set so as to be equal to the peripheral speed of the first roller pair. The second speed is set so as to be equal to a peripheral speed of the second roller pair in a state in which a slip of the torque limiter is not caused.