Sheet Dispenser Stepper Control for Jam-Free Paper Feed
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Solution Overview
Problem
Conventional automated sheet product dispensers experience paper jamming and excessive wear due to abrupt motor speed changes and failure to disengage the sheet from the tear bar, leading to inefficient dispensing and product damage.
Innovation Solution
The implementation of a sheet product dispenser using a DC stepper motor with controlled acceleration and deceleration during the dispense cycle, combined with a roller assembly featuring flexible rubber portions and a baffle to prevent overspin, and a modular design with support arms and shaft plugs for improved stability and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electric drive motors are used with abrupt activation and deactivation during dispense cycle, then dispensing speed and productivity are improved, but paper jamming and excessive parts wear occur
Solution Approach 1:
The motor control system dynamically adjusts speed during the dispense cycle, transitioning from abrupt on/off control to continuous variable speed control. The motor operates at high speed during mid-dispense for productivity while gradually reducing speed at start and end to prevent jamming and wear, resolving the contradiction between speed and reliability.
Solution Approach 2:
The invention changes the operational parameters of the motor by implementing a multi-stage speed profile. Instead of constant high speed, the motor speed is varied through different phases: acceleration phase, constant speed phase, and deceleration phase. This parameter change allows maintaining high productivity during the constant speed phase while preventing harmful effects during acceleration and deceleration phases.
2Productivity
If motor speed is increased for faster dispensing, then productivity improves, but impulse loads increase causing paper damage and jamming
Solution Approach 1:
The motor operation follows a periodic speed profile with distinct phases: acceleration, constant speed, and deceleration. This periodic variation in speed ensures that high dispensing rates are maintained during the constant speed phase while impulse loads are minimized during acceleration and deceleration phases, resolving the contradiction between productivity and paper damage.
3Device complexity
If sheet product remains engaged with tear bar after dispensing, then simple mechanism is maintained, but jamming occurs during subsequent cycles
Solution Approach 1:
The motor control system performs a preliminary deceleration action before the dispense cycle ends, gradually reducing motor speed and paper feed rate. This preliminary action ensures the sheet is fully separated from the tear bar before the next cycle begins, preventing jamming without adding complex mechanical disengagement mechanisms.
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 minimizes product damage and jamming by controlling the acceleration and deceleration of the sheet product, reduces impulse loads, and enhances the assembly and stability of the dispenser, resulting in improved operational efficiency and reduced wear.
Implementation Method 1
a control unit controlling the DC stepper motor to move the sheet product with a gradually increasing acceleration during a portion of the dispense cycle
Implementation Method 2
a plurality of flexible rubber portions spaced along a length of the roller frame, the rubber portions being overmolded onto the roller frame
Implementation Method 3
one of the support arms engaging a base extending away from a rear wall of the back cover and the other support arm being connected to the rear wall, wherein the base limits the deflection capability of one of the support arms, wherein insertion of the sheet product roll support shaft into hub ends causes the support arm connected to the rear wall to deflect to a substantially greater degree than the other support arm
Implementation Method 4
the shaft plug including an aperture for receiving a portion of a roller shaft and an aperture sized to receive a spring, the chassis defining a pair of plug retainers for holding the plugs and roller, the springs tending to bias the roller away from the spring retainers
Implementation Method 5
a baffle adapted to deflect upon contact with the roll of sheet product and remain engaged against the roll of sheet product during at least a significant portion of a roll life
Data Source
AI summary
A sheet product dispenser includes a sheet product feed mechanism coupled to a DC stepper motor, the mechanism moving a sheet product out of the dispenser during a dispense cycle; and a control unit controlling the DC stepper motor to move the sheet product with a gradually increasing acceleration during a portion of the dispense cycle.