Sonic Sensor Distance Measurement Using Reference Flat Surfaces

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Solution Overview

Problem

Existing printing apparatuses face challenges in accurately measuring the distance between a print head and a medium due to environmental changes such as temperature, humidity, and pressure, which affect sonic wave propagation and lead to measurement errors over time.

Innovation Solution

A printing apparatus with a carriage containing a sonic sensor and a flat surface unit with multiple flat surfaces at varying distances from the sonic sensor, allowing for the derivation of a relational expression between transmission/reception time and distance, enabling accurate distance measurement to the medium despite environmental changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a sonic sensor is used to detect the distance between the print head and the medium, then the distance can be measured continuously, but measurement errors occur due to environmental changes such as temperature, humidity and pressure

Engineering Contradiction:

Improvedistance measurement accuracyVSAvoidmeasurement stability under environmental changes

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the measurement parameters by measuring the transmission/reception time of sonic waves and using this time parameter combined with pre-stored speed data to calculate distance, rather than relying solely on direct sonic distance measurement. This parameter transformation allows compensation for environmental effects on sonic wave propagation speed.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary actions by pre-storing the relationship between transmission/reception time and distance in a table before actual printing. This pre-calibration data is used to compensate for environmental variations during printing operations, improving measurement reliability without requiring real-time environmental sensing.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the print head is used continuously for a long period of time, then printing productivity increases, but the print head is heated and the use environment of the sonic sensor significantly changes, resulting in measurement errors

Engineering Contradiction:

Improveprinting efficiencyVSAvoiddistance measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary calibration by measuring the transmission/reception time to a reference position and storing the corresponding distance relationship before printing begins. This pre-established reference data remains valid even as environmental conditions change during continuous printing, maintaining measurement accuracy throughout the printing process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism by continuously measuring the transmission/reception time of sonic waves and comparing it against the pre-stored reference data. The system uses this feedback to detect changes in the print head-to-medium distance and adjusts or flags measurements accordingly, maintaining accuracy during prolonged operation.

Inventive Principle:

Principle #23Feedback

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 solution allows for precise distance calculation to the medium, minimizing the impact of environmental changes and ensuring consistent printing quality by using the measured transmission/reception time and known distances, thus reducing measurement errors.

Implementation Method 1

Sonic waves change depending on changes in the environmental condition such as temperature, humidity and pressure

Methodology Applied

Scientific EffectSonic wave propagation: Sound

Implementation Method 2

measuring the distance from the medium... by measuring the transmission/reception time

Methodology Applied

Scientific EffectTime of flight measurement: Time of Flight

Data Source

PatentUS11007803B2Printing apparatus and distance measuring method of sonic sensor

Publication Date: 2021.05.18 SEIKO EPSON CORP

AI summary

A printing apparatus including a platen unit including a platen surface on which a medium is disposed; a carriage including a print head and a sonic sensor, the carriage being configured to move; and a flat surface unit including a plurality of flat surfaces disposed such that distances between the sonic sensor and the plurality of flat surfaces are different from each other. The printing apparatus derives a relational expression from a surface-by-surface distance difference among the flat surfaces of the flat surface unit and a transmission/reception time to and from each surface, obtained based on a measurement by the sonic sensor, and determines, from the relational expression and the transmission/reception time measured at the medium, a distance to the medium.