ATM Currency Detection Using Dual State Counters
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Solution Overview
Problem
Existing paper currency detection systems in ATMs struggle to accurately detect damaged or foreign paper currencies, leading to multiple record entries for a single currency due to design variations and damage, which interferes with the state machine's ability to maintain a consistent record sequence.
Innovation Solution
A paper currency detection apparatus and method utilizing a sensor unit, storage unit, and control unit with two state counters to differentiate between 'paper currency temporal arrival' and 'leave' states, and a preset threshold to eliminate interference, ensuring a consistent record sequence by adjusting counters and storage pointers based on detected signal states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single state counter is used to detect paper currency states, then the device complexity is low, but the measurement precision deteriorates because multiple arrival/leave states occur for damaged currencies
Solution Approach 1:
The patent divides a single state counter into two separate state counters: a first state counter for counting paper currency arrival states and a second state counter for counting paper currency leave states. This segmentation allows independent tracking of arrival and leave events, enabling accurate detection even when damaged currencies cause multiple state transitions. The segmentation resolves the contradiction by improving measurement precision through separate counting mechanisms while keeping each individual counter relatively simple.
2Reliability
If traditional state machine recording is used, then the device complexity is low, but the reliability deteriorates because multiple record entries are generated for a single currency
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the states of both state counters and adjusts the recording pointer accordingly. When the first state counter reaches an arrival state and the second state counter shows zero or exceeds a threshold, the control unit updates the pointer to record the currency information. This feedback-based control ensures that only valid, non-duplicate records are created, improving reliability while managing control logic complexity through systematic state monitoring.
3Measurement precision
If no threshold judgment is applied, then the ease of operation is high, but the measurement precision deteriorates because temporary states are misidentified as valid currency states
Solution Approach 1:
The patent introduces a threshold parameter for the second state counter to distinguish between temporary states (caused by damaged currency) and valid currency states. When the second state counter exceeds this threshold, the system recognizes a genuine paper currency presence rather than a temporary interference. This parameter-based differentiation improves measurement precision by filtering out false states while maintaining ease of operation through a straightforward threshold comparison mechanism.
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
Effectively eliminates interference from damaged currencies and foreign matter, ensuring the record sequence matches the transmission sequence, thereby improving the accuracy of paper currency detection in ATMs.
Implementation Method 1
Detecting transmission states of a paper currency in a channel by using an optical sensor
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A paper-type detection device (1) comprises a sensor unit (10), a storage unit (20) and a control unit (30). The sensor unit (10) is used for detecting a transmission state of a paper (100) according to a fixed clock period, and carrying out binaryzation on detected signals to indicate the presence-absence state of the paper (100). The storage unit (20) is used for acquiring the signals detected by the sensor unit (10), acquiring paper (100) information in the signals, and storing the paper (100) information in sequence. The control unit (30) comprises a first state counter and a second state counter. The control unit (30) controls the two state counters for carrying out zero clearing and starting operations for counting in conjunction with the sensor unit (10), in order to eliminate the interference in a predetermined threshold value, so as to eliminate the interference brought by the paper (100) in a poor state and make sure that the information recording sequence of paper (100) is consistent with the transmission sequence of the paper (100). Also disclosed is a paper-type detection method.