Self-Checkout Vending Machine With Color-Coded Weight Verification

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Solution Overview

Problem

Existing self-checkout vending devices face challenges in detecting errors, such as when a product is not scanned during the checkout process, making the process cumbersome for operators.

Innovation Solution

A self-checkout sales device equipped with a weighing module, product scanner, and communication unit, utilizing a control unit with a state machine to control a light strip based on weight matching, providing visual feedback through colored lighting to indicate correct scanning and weighing states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a self-checkout vending device uses traditional error detection methods, then the device structure remains simple, but the operator cannot easily detect errors such as unscanned products

Engineering Contradiction:
Improveerror detection capabilityVSAvoiddevice structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses color-changing LED indicators to provide visual feedback about system state and errors. Different colors indicate different operational states, enabling intuitive error detection without complex interfaces. This resolves the contradiction by improving reliability through visual feedback while maintaining simple device structure.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent implements feedback mechanisms where the system provides real-time visual information about scanning status and weight verification through illuminated indicators. This feedback loop enables operators to immediately detect errors such as unscanned products or weight mismatches, improving error detection capability without significantly increasing device complexity.

Inventive Principle:
Principle #23Feedback

2Reliability

If the vending device provides detailed error detection feedback, then error detection capability improves, but the ease of operation decreases due to increased complexity

Engineering Contradiction:
Improveerror detection capabilityVSAvoidoperator interaction
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent uses color-coded LED indicators (e.g., green for correct, red for error) to provide intuitive visual feedback. This approach improves error detection capability while maintaining ease of operation by presenting information in a visually intuitive manner that requires minimal operator training or cognitive effort.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The system automatically detects and communicates errors through visual indicators, enabling the device to serve itself in monitoring its own state. This reduces the operational burden on the operator while maintaining high error detection capability, as the system actively informs rather than requiring active operator investigation.

Inventive Principle:
Principle #25Self-service

3Reliability

If the device uses continuous visual feedback, then error detection capability improves, but energy consumption increases

Engineering Contradiction:
Improvevisual feedback capabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic or conditional illumination of LEDs based on system state rather than continuous illumination. LEDs are activated only when relevant feedback is needed (e.g., during weighing, after scanning, or when errors occur), reducing energy consumption while maintaining effective error detection capability through strategically timed visual feedback.

Inventive Principle:
Principle #19Periodic 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

Facilitates intuitive interaction and error detection during self-checkout, ensuring accurate product verification and enabling seamless transaction completion.

Implementation Method 1

The deformation section has a strain gauge for measuring a weight acting on the load plate

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Implementation Method 2

The lighting strip comprises first, second, and third LED illuminants. The first LED illuminants generate light in a wavelength range from 450 nm to 500 nm, which corresponds to the color blue. The second LED illuminants generate light in a wavelength range from 500 nm to 570 nm, which corresponds to the color green. The third LED illuminants generate light in a wavelength range from 610 nm to 760 nm, which corresponds to the color red.

Methodology Applied
Scientific EffectLight-emitting diode: Light Emitting Diode

Data Source

PatentEP4488974B1Vending machine
Publication Date: 2025.07.02 BIZERBA GMBH & CO KG
  • EP4488974B1 patent drawingFigure 1
  • EP4488974B1 patent drawingFigure 2
  • EP4488974B1 patent drawingFigure 3

AI summary

The present invention relates to a self-checkout sales device comprising a weighing module, a product scanner for scanning product article numbers and a communication unit for sending and receiving article data to a network for storing article data.