Ultrasonic Sheet Feed Detection With Adaptive Wait-Time Control
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Solution Overview
Problem
Conventional sheet conveyance devices using ultrasonic sensors for multiple feeding detection are prone to errors due to fixed wait times and distance deviations between transmitter and receiver circuits, leading to incorrect detection of multiple feeding.
Innovation Solution
A sheet conveyance device with a control circuit that adjusts the wait time for charging based on the magnitude of the judgment voltage, allowing for dynamic adjustment of the wait time to improve detection accuracy by considering variations in distance and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed wait time is used for charging the receiver circuit output, then the device complexity is reduced and ease of operation is improved, but the measurement precision of multiple feeding detection deteriorates due to distance deviations and temperature changes
Solution Approach 1:
The wait time for charging the receiver circuit output is changed from a fixed value to a dynamically adjustable value based on the magnitude of the output voltage. The control circuit adjusts the wait time longer when the output voltage magnitude is smaller (indicating larger distance deviation or temperature effect) and shorter when the magnitude is larger, thereby maintaining detection accuracy under varying conditions.
Solution Approach 2:
The patent changes the parameter of wait time from a static fixed value to a variable that adapts based on the output voltage magnitude. By monitoring the voltage magnitude and adjusting the charging duration accordingly, the system compensates for environmental variations and installation errors without requiring complex calibration procedures.
2Measurement precision
If the wait time is extended to capture the peak output voltage, then the measurement precision improves, but the loss of time increases and productivity decreases
Solution Approach 1:
The wait time is dynamically adjusted based on the actual output voltage magnitude rather than using a consistently extended fixed time. This allows the system to achieve peak voltage capture when needed (improving precision) while minimizing unnecessary waiting time during normal operations (maintaining productivity).
Solution Approach 2:
The charging wait time parameter is changed from a static extended value to a variable that adapts to real-time conditions. By adjusting the wait time based on voltage magnitude, the system achieves accurate peak capture only when necessary, thereby balancing detection precision with operational efficiency.
3Measurement precision
If the charging time is extended to include the peak output voltage, then the measurement precision improves, but the loss of time increases
Solution Approach 1:
The charging time is dynamically adjusted based on the magnitude of the output voltage. When the voltage magnitude indicates that the peak is delayed (due to distance or temperature effects), the charging time is extended accordingly. When the peak is expected sooner, the charging time is shortened, thus avoiding unnecessary time loss while maintaining measurement accuracy.
Solution Approach 2:
The charging time parameter is transformed from a fixed extended duration to a variable that adapts to the actual signal characteristics. This dynamic parameter adjustment ensures that the charging window captures the peak voltage when needed without consistently extending the charging time, thereby reducing overall time loss.
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
The dynamic adjustment of wait time enhances the accuracy of multiple feeding detection, reducing errors caused by installation errors and temperature changes, thereby ensuring reliable operation of the sheet conveyance system.
Implementation Method 1
a transmitter circuit (7S) provided on a conveyance path for sheets fed out by a sheet feed rotary body (52), and transmitting ultrasonic waves
Implementation Method 2
a receiver circuit (7R) provided on the conveyance path for sheets and outputting an electric charge in accordance with intensity (strength) of ultrasonic waves received
Implementation Method 3
an integrator circuit (70) performing charging of electric charge outputted from the receiver circuit (7R)
Data Source
AI summary
A sheet conveyance device includes a transmitter circuit, a receiver circuit, an integrator circuit which performs charging of electric charge outputted from the transmitter circuit and outputs a judgment voltage, a drive circuit, and a control circuit. The drive circuit feeds a drive signal to the transmitter circuit. At a lapse of a wait time after changing a level of a transmission instruction signal to a level instructing to feed the drive signal to the transmitter circuit, the control circuit makes the integrator circuit start to perform charging. When adjusting the wait time, the control circuit performs processing for adjustment a plurality of times. The control circuit makes the wait time different in each execution of the processing for adjustment. The control circuit determines a new wait time based on a magnitude of the judgment voltage recognized in each execution of the processing for adjustment.