Flexible Ink Pouch Empty-State Detection via Pump Signal Frequency
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Solution Overview
Problem
Ink containers with rigid outer containers and inner, flexible fluid pouches cannot be accurately monitored for empty state using conventional fill level sensors, as the imploding pouch renders vertical fill level measurements irrelevant and non-proportional to the remaining ink volume.
Innovation Solution
A device connected to the ink container via a fluid conduit, which uses a pump to output an electrical signal whose frequency is proportional to the pump's rotational speed. The device includes an evaluation unit that monitors the signal frequency, determining the empty state by detecting when the frequency falls below a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fill level sensors are used to monitor the ink container, then the monitoring system is simple, but the measurement precision deteriorates because the imploding pouch renders vertical fill level measurements irrelevant and non-proportional to the remaining ink volume
Solution Approach 1:
The patent replaces conventional mechanical fill level sensors with a pump-based monitoring system that uses electrical signal frequency analysis. The pump's rotational speed, reflected in the frequency of its electrical signal, serves as an indirect but accurate indicator of ink volume. This substitution resolves the contradiction by achieving high measurement precision through a different physical principle that is compatible with the flexible pouch design.
Solution Approach 2:
The patent introduces an intermediary evaluation unit that analyzes the frequency of the pump's electrical signal to determine the empty state. This intermediary component translates the pump's operational characteristics into meaningful information about ink volume, enabling accurate detection without direct contact with the imploding pouch and thus maintaining both precision and system simplicity.
2Productivity
If the pump runs at high speed to quickly empty the ink container, then the productivity improves, but the measurement precision deteriorates due to short-term fluctuations in pump speed that cause incorrect empty state indications
Solution Approach 1:
The patent applies preliminary action by establishing a threshold frequency value before the emptying process begins. This pre-defined threshold serves as a reference point that remains valid throughout the pumping operation, allowing the system to distinguish between normal speed fluctuations and actual empty state conditions. The evaluation unit compares the current frequency against this pre-established threshold to make accurate determinations.
Solution Approach 2:
The patent employs dynamics by continuously monitoring the pump's electrical signal frequency in real-time and comparing it against the threshold. Rather than using a fixed speed setting, the system dynamically adjusts its assessment based on the current frequency reading, enabling accurate empty state detection even as the pump operates at varying speeds to maintain high productivity.
3Measurement precision
If the pump resistance is used to detect the empty state, then the measurement precision improves for near-complete emptying, but the device complexity increases due to the need for frequency monitoring and threshold evaluation
Solution Approach 1:
The patent applies universality by making the pump serve multiple functions: it both conveys ink from the container and provides the signal for empty state detection. The same pump motor that drives the emptying process also generates the electrical signal whose frequency is monitored to determine when the ink is depleted. This multi-functionality achieves high measurement precision without adding separate monitoring hardware, thus avoiding increased device complexity.
Solution Approach 2:
The system implements self-service by using the pump's own electrical signal to monitor its own operational state and detect empty conditions. The pump essentially monitors itself through the frequency of its drive signal, eliminating the need for external sensors or additional monitoring components. This self-service approach achieves accurate near-complete emptying detection while keeping the overall system simple.
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 allows for accurate determination of the empty ink state, preventing incorrect indications due to short-term pump speed fluctuations and enabling nearly complete emptying detection.
Implementation Method 1
the fluid pouch has the property that, when the fluid pouch is nearly empty and additional fluid is pumped out of the fluid pouch by means of the pump, in this event a 'pump resistance' appears in the fluid pouch that counteracts a further emptying of said fluid pouch
Data Source
AI summary
Provided is a device for determining an empty ink state of an ink container for an ink printing system. The ink container has a rigid outer container and an inner, flexible fluid pouch. The inner fluid pouch is connected via a fluid conduit to a pump that is configured to convey fluid out of the inner fluid pouch. The pump is configured to output an electrical signal whose periodicity is proportional to a rotational speed of the pump. The device has an evaluation unit that is configured to monitor the frequency of the electrical signal and, upon the frequency falling below a predetermined threshold, to output that the ink container is empty.