Printer Carriage Speed Correction Using Linear Encoder Feedback
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Solution Overview
Problem
Printers experience changes in carriage speed due to variations in motor rotation speed caused by eccentricity between the motor shaft and encoder, leading to inaccuracies in speed control.
Innovation Solution
A method involving a linear encoder to measure carriage position, calculating differences in motor shaft rotation positions, and applying correction values to the motor encoder measurements to stabilize the carriage speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the motor encoder measures the rotation position of the motor shaft to control rotation speed, then the rotation speed control is simplified, but the measurement precision deteriorates due to eccentricity between the motor shaft and encoder
Solution Approach 1:
The patent introduces a linear encoder as an intermediary measurement device to indirectly measure the motor shaft's rotation position. Instead of directly measuring the rotating shaft (which causes eccentricity errors), the linear encoder measures the linear displacement of the carriage, which is then converted to rotation position information. This mediator approach eliminates the eccentricity problem while maintaining measurement precision.
Solution Approach 2:
The patent replaces the direct mechanical coupling between the motor encoder and motor shaft with an optical measurement system. The linear encoder uses optical fields to measure linear displacement, substituting the direct mechanical measurement approach that suffers from eccentricity. This substitution maintains measurement accuracy while simplifying the control system.
2Device complexity
If the motor shaft and encoder are directly coupled for simple speed control, then the device complexity is reduced, but the manufacturing precision deteriorates due to eccentricity
Solution Approach 1:
The linear encoder serves as a mediator that measures the actual carriage position rather than relying on indirect motor shaft measurements. This intermediary measurement system eliminates the need for precise mechanical coupling between the encoder and motor shaft, reducing manufacturing precision requirements while maintaining overall system accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where the linear encoder's measurements of actual carriage position are fed back to correct the rotation position calculations. This feedback loop compensates for any remaining errors and ensures high manufacturing precision without requiring complex mechanical coupling.
Data Source
AI summary
A motor of a printer is capable of rotating at a rotation speed controlled to be constant based on a rotation position of a motor shaft measured by a motor encoder so as to move a carriage. A linear encoder measures positions of the carriage in a moving direction. Differences between each of rotation positions of the motor shaft based on the measurement by the motor encoder and a corresponding rotation position of the motor shaft based on the measurement by the linear encoder are calculated, for positions rotation during one or more rotation(s) of the motor shaft. A correction value to be added to the rotation positions of the motor shaft measured by the motor encoder is determined, based on the calculated differences, such that a change in the rotation speed of the motor shaft, during one rotation thereof, based on the measurement by the linear encoder, is decreased.