Liquid Discharge Apparatus Sub Tank Pressure Control
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Solution Overview
Problem
In liquid discharge apparatuses based on the station system, maintaining internal pressure for purge operations can be inadequate due to insufficient ink volume in the sub tank, leading to ineffective maintenance, and using large pumps increases size and cost.
Innovation Solution
A liquid discharge apparatus with a judging mechanism that supplements the sub tank with liquid before purge operations, ensuring sufficient internal pressure is achieved without large pumps, using a charge tank for compressed air and optimizing unoccupied volume to satisfy specific pressure and volume conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-sized pump is installed to raise the internal pressure of the sub tank sufficiently for purge operations, then the purge operation effectiveness is improved, but the liquid discharge apparatus becomes large-sized and expensive
Solution Approach 1:
The patent applies preliminary action by supplementing the sub tank with liquid before performing the purge operation. The judging mechanism detects when the liquid amount is insufficient, and the liquid supplement section adds liquid in advance, ensuring sufficient internal pressure can be achieved during purge without requiring an oversized pump. This resolves the contradiction by preparing the system beforehand rather than relying on excessive pump capacity.
2Reliability
If the liquid amount in the sub tank is insufficient before purge operation, then the internal pressure cannot be raised sufficiently for effective purge, but supplementing liquid increases the unoccupied volume and may affect discharge characteristics
Solution Approach 1:
The patent implements feedback through the judging mechanism that continuously monitors the liquid amount in the sub tank. When the liquid amount falls below a predetermined threshold, the system automatically activates the liquid supplement section to add liquid. This closed-loop feedback control ensures the liquid amount is maintained within the optimal range, achieving sufficient internal pressure for purge while preventing excessive liquid that would compromise discharge characteristics.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the liquid amount in the sub tank based on operational conditions. The judging mechanism detects parameter changes (liquid amount), and the system modifies the liquid volume to maintain optimal pressure conditions for purge operations while preserving discharge head performance characteristics.
3Reliability
If liquid is supplemented continuously to maintain optimal amount in sub tank, then purge operation reliability is improved, but maintenance time increases
Solution Approach 1:
The patent applies periodic action by supplementing liquid only when the judging mechanism detects that the liquid amount has fallen below the predetermined threshold, rather than continuously. This periodic supplementation based on actual need maintains reliable purge operations while minimizing the time spent on maintenance activities, as liquid is added only when necessary rather than on a fixed schedule.
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 approach allows for effective maintenance by ensuring sufficient internal pressure in the sub tank during purge operations, reducing the need for large pumps and maintaining discharge characteristics while minimizing the supplement liquid amount and maintenance time.
Implementation Method 1
a charge tank 110a for storing compressed air; the unoccupied volume VS of the sub tank, which is a volume of the sub tank not occupied by the liquid, satisfies the following expression: VS≤{(PC−PS0)/(PS0−P0)}×VC
Data Source
AI summary
A liquid discharge apparatus includes a discharge head which discharges a liquid from a discharge port onto a recording medium to form an image, a sub tank which is movable together with the discharge head and which stores the liquid to be supplied to the discharge head, a liquid supplement section which supplements the sub tank with the liquid, a purge section which performs a purge operation in which the liquid in the sub tank is pressurized to be fed to the discharge head, and the liquid in the discharge head is forcibly discharged from the discharge ports, a judging mechanism which judges whether or not an amount of the liquid in the sub tank is not more than a predetermined amount V1, and a controller which controls the liquid supplement section and the purge section.