Liquid Ejection Apparatus Conveyor Malfunction Detection
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Solution Overview
Problem
The existing liquid ejection apparatuses require a longer time to initiate liquid ejection onto a recording medium due to the need to determine conveyor mechanism malfunctions after uncapping, which can lead to increased downtime and potential collisions between the recording medium and the capping mechanism.
Innovation Solution
Incorporating a recording-medium sensing device and a controller that allows for conveyor mechanism determination while the ejection space is still capped, enabling early detection of malfunctions and reducing the time from uncapping to liquid ejection, and stopping the conveyor mechanism when the medium is sensed to prevent collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conveyor mechanism is driven continuously for a predetermined length of time to determine malfunction, then the reliability of the conveyor mechanism is improved, but the time required until the start of liquid ejection is increased
Solution Approach 1:
The patent applies preliminary action by performing the malfunction determination during the capping phase before uncapping occurs. The controller drives the conveyor mechanism for a first period while the ejection space is capped, and if no recording medium is sensed, it determines the conveyor mechanism is normal before proceeding to uncapping. This shifts the timing of the reliability check to an earlier stage, eliminating the delay that would otherwise occur after uncapping.
Solution Approach 2:
The patent introduces dynamic timing based on the actual presence of a recording medium. Instead of a fixed continuous drive period, the controller adjusts the drive duration based on whether the recording medium is detected during the capping phase. If the medium is sensed within the first period, the drive stops early; if not, the full first period is completed before uncapping. This dynamic adjustment optimizes both time and reliability.
2Productivity
If the cap is moved from close-contact position to distant position to allow recording medium passage, then the productivity is improved, but the risk of recording medium collision with cap increases
Solution Approach 1:
The patent applies feedback by using the recording-medium sensing device to detect the presence of the recording medium at the upstream end of the conveyance path. The controller receives this feedback signal and uses it to control the timing of the cap movement and conveyor operation. When the recording medium is detected, the controller stops the conveyor mechanism before the cap moves to the distant position, preventing collision while still allowing productive operation.
3Reliability
If the conveyor mechanism is stopped to prevent recording medium collision with cap, then the safety is improved, but the time required for maintenance operation is increased
Solution Approach 1:
The patent applies preliminary action by performing the collision prevention stop during the capping phase before uncapping and liquid ejection begin. The controller monitors for recording medium presence during the first drive period while capped, and stops the conveyor mechanism early if the medium is detected, rather than waiting until after uncapping. This early intervention prevents collision while minimizing overall maintenance time.
Solution Approach 2:
The patent maintains continuity of useful action by overlapping the conveyor drive with the capping operation. Instead of stopping the conveyor completely during maintenance, the controller drives it for the first period while capped (useful action continues), then stops it only when necessary based on recording medium detection. This approach maintains productivity where possible while ensuring safety when needed.
Data Source
AI summary
A liquid ejection apparatus including: a head having an ejection face and configured to eject liquid toward a recording medium; a capping mechanism which switches the ejection space being opposite the ejection face between capped and uncapped states; a conveyor which conveys the recording medium along a conveyance path; a sensor which senses whether the recording medium is present at a sensing position located on an upstream portion of the conveyance path; and a controller configured to: control the capping mechanism and the conveyor; determine whether the conveyor is normal, based on driving of the conveyor for a first period from the start of the driving of the conveyor in the capped state; and when the recording medium is sensed by the sensor within the first period, stop the driving of the conveyor even before the first period passes from the start of the driving of the conveyor.