Printer Fault Detection Circuit Using Discrete Resistors
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Solution Overview
Problem
Current fault detection circuits for printers with multiple print heads, such as thermal and impact print heads, fail to detect failures until after many receipts or checks are printed, and existing solutions are costly and ineffective for impact print heads.
Innovation Solution
A single fault detection circuit using a test power supply, resistors, and an analog-to-digital converter to test the resistance of each print head element, generating a notification signal if the detected voltage deviates beyond a threshold, allowing for early detection of faults in both thermal and impact print heads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If operational amplifier components are used in fault detection circuits for thermal print heads, then fault detection capability is improved, but circuit cost increases significantly
Solution Approach 1:
The patent replaces expensive operational amplifier components with inexpensive discrete components (resistors, capacitors, transistors) that can be easily sourced and implemented. The fault detection circuit uses standard through-hole components rather than integrated operational amplifiers, significantly reducing component cost while maintaining detection functionality.
Solution Approach 2:
The patent substitutes the electronic operational amplifier-based detection system with a simpler resistor-capacitor-transistor based detection circuit. This replacement eliminates the need for complex integrated circuits and uses basic electronic components that are cheaper and easier to manufacture.
2Reliability
If existing fault detection circuits are used for thermal print heads, then thermal print head faults can be detected, but impact print head faults are not detected
Solution Approach 1:
The patent designs a universal fault detection circuit that can detect faults in both thermal print heads and impact print heads using the same circuit architecture. The circuit measures resistance across print head elements and can identify faults in different print head types without requiring separate detection circuits, thereby achieving multi-functionality.
Solution Approach 2:
The patent segments the fault detection approach by creating separate measurement paths for different print head types within the same circuit. The circuit can selectively test thermal print head elements or impact print head elements by switching between different test configurations, allowing comprehensive coverage of multiple print head types.
3Productivity
If fault detection is performed after many receipts or checks are printed, then printing capacity is maintained, but fault detection timing is delayed
Solution Approach 1:
The patent implements fault detection that can be performed between printing jobs or during idle periods, allowing early detection of faults before they affect printing capacity. The circuit continuously monitors print head element resistance and can detect faults during non-printing intervals, enabling proactive maintenance without interrupting printing operations.
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 early detection of faults in multiple print heads, reducing downtime and maintenance costs by characterizing print head elements and notifying personnel or software when service is required, without the need for expensive operational amplifier components.
Implementation Method 1
In response to a flow of current from the test power supply through the first resistor and one of the plurality of elements in the first print head, the analog to digital converter detects a first voltage. If the one element in the first print head is operating in accordance with an acceptable operational characteristic, the first voltage is described by: v1 = v66 * (res116 / (res116 + element1))
Implementation Method 2
an analog to digital converter in signal communication with the second resistor. The first resistor is in series connection between the test power supply and the plurality of elements in the first print head. The second resistor is in series connection with the test power supply, the first resistor, and the plurality of elements in the second print head.
Data Source
AI summary
A fault detector apparatus for a printer having a first print head and a second print head with a plurality of print head elements in each print head is disclosed. The apparatus includes a test circuit in signal communication with all the print heads to test the plurality of print head elements. The test circuit includes a test power supply for generating a test voltage, a first resistor, a second resistor, and an analog to digital converter in signal communication with the second resistor. The first resistor is in series connection between the test power supply and the plurality of elements in the first print head. The second resistor in series connection with the test power supply, the first resistor, and the plurality of elements in the second print head. The fault detector apparatus will also work for a printer with only one print head.