Printer Motor Current Sensing for Media Low Detection
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Solution Overview
Problem
Conventional printers face challenges in detecting low media supply without increasing hardware footprint, which can lead to overheating and excessive wear on the print head when operated without paper.
Innovation Solution
A printer circuit and apparatus that utilize a motor coupled with a platen roller, a current sense resistor, and a current measuring circuit to determine the current draw by the motor, which is proportional to the amount of print media left, triggering a media low message and alert when the current falls below a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional low paper sensing systems are used, then media low detection is achieved, but hardware footprint increases
Solution Approach 1:
The motor serves multiple functions: it drives the platen roller for paper feeding and simultaneously acts as a sensor through its current draw characteristics. The existing motor is repurposed to detect media low conditions without requiring separate sensing hardware, thereby achieving multi-functionality and reducing overall system complexity
Solution Approach 2:
The motor's own electrical characteristics (current draw) are utilized to detect its operational state and the media condition. The system uses the motor's self-generated signal (current variation) to inform the control mechanism about paper availability, eliminating the need for external sensing components
2Productivity
If printer operates without paper, then printing continues, but print head overheats and wears excessively
Solution Approach 1:
The control mechanism continuously monitors the motor's current draw and uses this feedback to detect when paper is depleted. When the current falls below the threshold indicating no paper presence, the system generates a media low message to stop printing, preventing the print head from operating without paper and thus avoiding overheating and excessive wear
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 detects low media supply without additional hardware, preventing overheating and wear on the print head, and providing a low-footprint solution for space-constrained desktop printers.
Implementation Method 1
a current sense resistor coupled in series with the motor, a current measuring circuit comprising an operational amplifier circuit configured to receive input voltage and output voltage of the current sense resistor, generate a differential voltage based at least in part on the input voltage and the output voltage
Implementation Method 2
a current measuring circuit comprising an operational amplifier circuit configured to receive input voltage and output voltage of the current sense resistor, generate a differential voltage based at least in part on the input voltage and the output voltage, and convert the differential voltage to a current
Implementation Method 3
a motor coupled to a platen roller, a current sense resistor coupled in series with the motor... the motor drives the platen roller to draw print media from a media supply
Data Source
AI summary
Printer circuits and components for detecting a media low condition on a printer are provided. The printer circuit comprises a motor coupled to a platen roller, a current sense resistor coupled in series with the motor, a current measuring circuit comprising an operational amplifier circuit configured to receive input voltage and output voltage of the current sense resistor, generate a differential voltage based at least in part on the input voltage and the output voltage, and convert the differential voltage to a current, and an analog-to-digital converter and control mechanism configured to receive the current from the current measuring circuit and control operation of the motor based at least in part on the current.