Spectral Characteristic Acquisition Device for High-Speed Inline Measurement

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Solution Overview

Problem

Existing image formation apparatuses face challenges in achieving high-speed color tone control and spectral characteristic measurement due to the time-consuming nature of traditional spectrometry methods, which are inadequate for high-speed printing applications and require extensive labor and resources for preparing transformation matrices.

Innovation Solution

A spectral characteristic acquisition device that uses a line illumination light source, collimator lens, micro-lens array, hole array, imaging optical system, diffraction element, and line sensor to estimate spectral characteristics through a transformation matrix, with a calibration unit for improving estimation precision and correcting sensor data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional spectrometry methods are used to measure spectral characteristics, then measurement precision is improved, but measurement speed deteriorates and time consumption increases

Engineering Contradiction:
Improvespectral characteristic measurement precisionVSAvoidmeasurement speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The spectrum is segmented into multiple wavelength bands (e.g., 31 bands from 400-700nm), and a line sensor with multiple pixels simultaneously detects light intensity in each band. This parallel detection approach maintains measurement precision while dramatically improving measurement speed, enabling high-speed spectral characteristic acquisition suitable for inline measurement in printing applications.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from sequential wavelength-by-wavelength detection to simultaneous multi-wavelength detection by adding the spatial dimension through a line sensor array. Multiple pixels detect different wavelength bands at the same time, converting a one-dimensional sequential measurement process into a two-dimensional parallel process, thereby achieving both high precision and high speed.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If multiple transformation matrices are prepared for different measurement objects to improve estimation precision, then spectral characteristic estimation precision is improved, but device complexity and labor requirements increase

Engineering Contradiction:
Improvespectral characteristic estimation precisionVSAvoidtransformation matrix management complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent develops a universal transformation matrix that can estimate spectral characteristics for various measurement objects (different papers, inks, print conditions) without requiring separate matrices for each object type. This single matrix handles multiple functions and object types, reducing device complexity and eliminating the need to manage numerous transformation matrices while maintaining estimation precision.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

Instead of creating and managing multiple physical transformation matrices for different objects, the system uses a single copied/universal matrix that works across different object types. This approach simplifies the system by replacing multiple specialized components with one general-purpose component that serves all measurement needs.

Inventive Principle:
Principle #26Copying

3Measurement precision

If extensive standard samples are prepared and measured to obtain transformation matrices, then estimation precision is improved, but labor and time requirements increase

Engineering Contradiction:
Improvespectral characteristic estimation precisionVSAvoidtime for standard sample preparation and measurement
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The transformation matrix is pre-calculated and stored in the system before actual measurement operations. This preliminary preparation eliminates the need for time-consuming standard sample measurements during operation, allowing the system to quickly estimate spectral characteristics for any measurement object using the pre-computed matrix, thereby saving significant time and labor.

Inventive Principle:
Principle #10Preliminary action

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

Enables high-precision spectral characteristic estimation at high speeds, reducing color difference errors and improving measurement efficiency, while minimizing the need for extensive standard sample preparation and labor.

Implementation Method 1

light irradiation means for irradiating a measurement object with light

Methodology Applied
Scientific EffectLight: Light

Implementation Method 2

diffraction means for diffracting light reflected from the measurement object to form a diffraction image

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 3

light-receiving means for receiving the diffraction image and outputting a signal depending on an amount of light in each different wavelength band

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP2916116B1Spectral characteristic acquisition device, image evaluation device, and image formation apparatus
Publication Date: 2020.05.20 RICOH CO LTD
  • EP2916116B1 patent drawingFigure 1
  • EP2916116B1 patent drawingFigure 2
  • EP2916116B1 patent drawingFigure 3

AI summary

A spectral characteristic acquisition device includes a light irradiation part configured to irradiate an object with light, a diffraction part configured to diffract light reflected from the object to provide diffracted light, a light-receiving part configured to receive the diffracted light and output a signal based on an amount of the diffracted light, a calibration color index configured to include a color with a known spectral characteristic, and an operation part configured to calculate a spectral characteristic of the object from a signal output from the light-receiving part by using a predetermined transformation matrix and calibrate the transformation matrix by using the calibration color index.