Image Forming Sensor Abnormality Detection Using Current Baselines
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately determining sensor abnormalities due to variations in circuit constants and individual differences among sensors, leading to complex and inefficient abnormality detection processes.
Innovation Solution
The implementation of a current detector to measure the total current value supplied to multiple sensors, with a CPU acquiring a reference value in a normal state and comparing it to detected values to determine sensor abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current detection circuit is provided for each sensor, then the abnormality of each sensor can be detected, but a huge number of ports and circuits are required
Solution Approach 1:
The patent merges multiple current detection functions into a single current detection circuit by connecting multiple sensors in parallel. The control unit calculates individual sensor currents by subtracting currents measured at different timings, eliminating the need for separate detection circuits for each sensor while maintaining detection accuracy.
Solution Approach 2:
The single current detection circuit serves multiple sensors simultaneously by performing sequential measurements and computational differentiation. The same circuit is used to detect currents for all sensors through timing-based separation and mathematical processing.
2Device complexity
If the abnormality of each sensor is detected only by the change of the detected current value, then one current detection circuit can be used, but it is difficult to detect whether one sensor is abnormal because the minimum current varies due to variation in circuit constant or individual difference of the sensors
Solution Approach 1:
The system performs preliminary current measurements for all sensors before operational use to establish baseline current values. These reference values are stored and used for comparison during operation, enabling accurate abnormality detection despite variations in circuit constants and sensor individual differences.
Solution Approach 2:
The control unit continuously monitors current values and compares them against reference values, providing feedback to determine sensor abnormality. The system uses differential measurement techniques where currents are measured at different timings and subtracted to isolate individual sensor contributions.
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
This method allows for accurate and simple detection of sensor abnormalities, accounting for variations and individual differences, thereby enhancing the reliability of sensor operation.
Implementation Method 1
a sensor 20 including a light emitting element 20a and a light receiving element 20b, a controller 30 including a CPU may turn on/off the light emitting element 20a formed of an LED
Implementation Method 2
a detection sensor for detecting a characteristic of the sheet
Data Source
AI summary
An image forming apparatus includes: a plurality of sensors that detect a state in the image forming apparatus; a power supply that supplies power to each of the plurality of sensors; a current detector that detects a current value of a current supplied from the power supply to each of the plurality of sensors; an acquisitor that acquires, as a reference value, a current value of a current supplied from the power supply to each of the plurality of sensors in a state in which the plurality of sensors are normal, and a determiner that determines whether the plurality of sensors are normal, by comparing the current value detected by the current detector with the reference value.