Rotary Encoder Segmentation for Printer Motor Control
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Solution Overview
Problem
Printers face challenges in achieving high-resolution motor control and suppressing high-frequency signal issues from encoders, which complicates the circuit configuration and manufacturing of disc-shaped scales with narrow slits or increased diameters.
Innovation Solution
A printer system with a rotary encoder featuring multiple detectors and signal generators that output signals with specific frequencies, allowing a controller to switch between different control modes based on the rotational speed and position of the motor, simplifying the circuit configuration and enhancing resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the diameter of the scale is increased to output high-resolution signals, then the measurement precision is improved, but the device complexity increases and it becomes difficult to arrange the scale in compact printers
Solution Approach 1:
The patent divides the scale into multiple segments with different numbers of slits (e.g., first scale with 360 slits, second scale with 720 slits). Each segment provides different resolution levels, allowing the system to achieve high measurement precision without requiring a single large-diameter scale. This segmentation resolves the contradiction by providing high resolution through multiple smaller components rather than one large component.
2Measurement precision
If the pitches of the slits are made narrow to output high-resolution signals, then the measurement precision is improved, but the manufacturing precision requirements increase significantly
Solution Approach 1:
Instead of creating one scale with extremely narrow slit pitches that are difficult to manufacture, the patent segments the encoding function across multiple scales with wider, more manufacturable slit pitches. The first scale has coarser pitch while the second scale has finer pitch, and their combined output achieves the desired high resolution without requiring any single scale to have impractically narrow slits.
Solution Approach 2:
The patent merges the output signals from multiple scales with different slit configurations to achieve high-resolution encoding. By combining the information from the first scale (360 slits) and second scale (720 slits), the system achieves equivalent resolution to a single scale with much narrower slits, thereby reducing manufacturing precision requirements while maintaining measurement precision.
3Speed
If the diameter of the scale is increased, then high-frequency signals are output at high motor speeds, but the circuit complexity increases to process these high-frequency signals
Solution Approach 1:
The patent segments the signal generation function across multiple scales rotating at different speeds. The first scale rotates at the motor speed and generates base-frequency signals, while the second scale rotates at twice the motor speed and generates high-frequency signals. This segmentation allows the system to handle high motor speeds without requiring a single large scale to generate and process extremely high-frequency signals, thereby reducing circuit complexity.
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
The solution enables high-resolution motor control with a simple configuration, reducing the complexity of processing high-frequency signals and improving positional accuracy and speed measurement, while maintaining the accuracy of conventional rotary scales.
Implementation Method 1
a sensor that senses the marks or slits of the scale to output given signals
Data Source
AI summary
An encoder is adapted to be opposed to a scale provided with a plurality of marks or slits arranged in a first direction at predetermined intervals. A plurality of detectors is arranged in a second direction perpendicular to the first direction while being staggered in the first direction, each of which detects a position of each of the marks or slits, and the plurality of detectors being operable to respectively output an detection signal which has a first frequency. A first signal generator is operable to generate an first output signal which has a second frequency which is 2n-times of the fist frequency based on the detection signal output from a first detector of the plurality of detectors. A second signal generator is operable to generate a second output signal which has the second frequency based on the detection signal output from a second detector of the plurality of detectors. A third signal generator is operable to generate a third output signal which has the second frequency based on the detection signal output from a third detector of the plurality of detectors. A fourth signal generator is operable to generate a fourth output signal which has the second frequency based on the detection signal output from a fourth detector of the plurality of detectors. A controller is operable to perform a switching control between a first predetermined control based on one of: 1) the first output signal and the third output signal; or 2) the second output signal and the fourth output signal output from the encoder, and a second predetermined control based on the first output signal, the second output signal, the third output signal, and the fourth output signal.