Display Refresh Rate Synchronization for Camera Code Reading

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Solution Overview

Problem

Interference fringes caused by synchronization issues between screen update timing of display devices and frame update timing of cameras hinder proper reading of two-dimensional codes.

Innovation Solution

Adjusting the refresh rate of the display device to a higher rate, specifically setting it to 150 Hz in code display mode, to synchronize with the camera's frame rate, reducing interference fringes and ensuring accurate code reading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the display device uses normal refresh rate for normal display, then power consumption is low, but interference fringes appear when displaying codes causing reading failure

Engineering Contradiction:
Improvecode reading accuracyVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The display device dynamically switches between normal refresh rate and high refresh rate based on the display content. When a code is detected, the refresh rate is increased to synchronize with the camera frame rate, eliminating interference fringes. After code display, it returns to normal refresh rate, thus achieving reliable code reading only when needed while minimizing overall power consumption.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The refresh rate parameter is changed from normal values (e.g., 60Hz) to a high value (e.g., 150Hz or higher) specifically during code display. This parameter change synchronizes the display updates with camera frame capture timing, preventing interference fringes and enabling accurate code reading without permanently increasing power consumption.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the refresh rate is increased to synchronize with camera frame rate, then interference fringes are reduced, but power consumption increases

Engineering Contradiction:
Improvecode reading accuracyVSAvoiddisplay device power consumption
Core Design Contradiction:
ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The high refresh rate is applied periodically only during code display intervals rather than continuously. The display controller detects when code content is being displayed and activates high refresh rate only during these periods, synchronizing with camera frame capture. This periodic application achieves reliable code reading while limiting power consumption increase to necessary time windows only.

Inventive Principle:
Principle #19Periodic action

3Productivity

If normal display settings are used, then power consumption is low, but code reading fails due to interference fringes

Engineering Contradiction:
Improvecode reading success rateVSAvoiddisplay device power consumption
Core Design Contradiction:
ProductivityVSUse of energy by stationary object

Solution Approach 1:

The system dynamically adapts the refresh rate based on operational requirements. During code display operations, it switches to high refresh rate to ensure successful code reading by synchronizing with camera timing. For normal display operations, it maintains low refresh rate to conserve power, thus achieving high productivity during code reading while minimizing overall energy consumption.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3757979B1Display control apparatus, display control method, and system
Publication Date: 2023.08.09 CANON KK
  • EP3757979B1 patent drawingFigure 1
  • EP3757979B1 patent drawingFigure 2
  • EP3757979B1 patent drawingFigure 3A~3C

AI summary

A multifunction inkjet printer (1) that displays an image on a display device (20) includes: an operation display unit (2) configured to receive an instruction from a user; and a CPU (101) configured to control the display device to display an image, wherein, in a state where display on the display device is being performed at a first refresh rate, in response to the operation display unit receiving an instruction for displaying a code to be captured by a mobile terminal, the CPU is configured to control the display device to display the code at a second refresh rate that has a higher frequency than the first refresh rate.