Variable Resistance Circuit for Optical Sensor Auto-Calibration
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Solution Overview
Problem
Existing printing apparatuses require manual adjustment of load resistance for optical sensors, which is time-consuming and prone to errors, especially when replacing components, due to variations in sensor sensitivity and resistance tolerance.
Innovation Solution
A printing apparatus with a variable resistance circuit comprising intercoupled resistors and drive elements, controlled by a shift register and controller, which automatically adjusts the total resistance to match the sensitivity of the optical sensor, allowing for precise detection and minimizing the need for manual adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual adjustment of volume resistor is used to match optical sensor sensitivity, then detection accuracy can be achieved, but adjustment time increases and reliability decreases when components are replaced
Solution Approach 1:
The patent replaces the mechanical manual adjustment of volume resistors with an automated electronic adjustment system. The microprocessor-controlled variable resistance circuit automatically adjusts the load resistance based on digital readings from the optical sensor, eliminating the need for manual mechanical adjustment and enabling rapid recalibration when components are replaced.
Solution Approach 2:
The system performs self-adjustment through automated feedback control. The microprocessor reads the optical sensor output, calculates the appropriate resistance value, and adjusts the variable resistance circuit automatically without requiring external manual intervention, thereby reducing adjustment time and improving reliability.
2Measurement precision
If manual adjustment of trimmer analog variable resistor is performed to achieve expected voltage output, then optical sensor sensitivity can be optimized, but the adjustment process becomes complex and requires adhesive bonding to prevent displacement
Solution Approach 1:
The patent replaces the mechanical trimmer analog variable resistor system with a digitally controlled variable resistance circuit. The microprocessor electronically adjusts the resistance through software control, eliminating the mechanical adjustment nob and associated adhesive bonding requirements, thereby simplifying the overall system.
Solution Approach 2:
The system changes the resistance parameter dynamically through digital control rather than fixed mechanical adjustment. The microprocessor can modify the resistance value in software, allowing flexible and precise control of the optical sensor output voltage without mechanical constraints.
3Ease of repair
If digital potentiometer is used with saved resistance value in nonvolatile memory, then resistance adjustment can be reused after substrate replacement, but tolerance variation of ±30% or more causes deviation from expected value
Solution Approach 1:
The patent implements a feedback control system where the microprocessor continuously monitors the actual optical sensor output and adjusts the variable resistance circuit accordingly. This closed-loop feedback mechanism compensates for component tolerances and ensures accurate resistance values even after substrate replacement, overcoming the ±30% tolerance limitation of standard digital potentiometers.
Solution Approach 2:
The system dynamically adjusts the resistance parameter based on actual sensor performance rather than relying on fixed tolerance specifications. By measuring the actual optical sensor output and calculating the required resistance adjustment, the system achieves precision beyond standard component tolerances.
4Adaptability or versatility
If optical sensor sensitivity varies greatly, then load resistance adjustment is necessary to absorb sensitivity differences, but this requires additional adjustment steps and increases operational complexity
Solution Approach 1:
The system automatically compensates for optical sensor sensitivity variations through self-adjustment. The microprocessor reads the sensor output, determines the appropriate load resistance, and adjusts the variable resistance circuit without requiring user intervention, thereby maintaining operational simplicity while achieving adaptability.
Solution Approach 2:
The system dynamically changes the load resistance parameter to match the specific optical sensor being used. By automatically adjusting the resistance based on the sensor's actual sensitivity characteristics, the system adapts to different sensors without requiring manual adjustment procedures.
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 solution enables automatic adjustment of the optical sensor's load resistance, reducing manual intervention and ensuring accurate detection without the need for recalibration when replacing components, while maintaining resistance variations within ±1%, improving efficiency and reliability.
Implementation Method 1
an optical sensor that detects gaps between labels or marks on an elongated sheet
Data Source
AI summary
A printing apparatus includes: a variable resistance circuit including a plurality of resistors intercoupled and one or more drive elements that feed currents through the respective resistors; an optical sensor coupled to the variable resistance circuit; a shift register that outputs signals to select one or more of the drive elements and to turn on the selected drive elements; and a controller that acquires a detection value of the optical sensor and that controls the shift register based on the detection value.