Printing Apparatus Sheet Discharge Jam Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image formation apparatuses face sheet discharge jams when printing on sheets with varying thickness, such as envelopes, due to the limited space between the sheet discharger and scanner, leading to premature contact and jamming issues, which are not effectively prevented by existing sensors that rely on uniform sheet thickness detection.
Innovation Solution
A printing apparatus with a sheet discharge tray tilted downward, an upper member limiting the space above the tray, a full sensor, a counter, and a controller that determines when to stop discharging based on the detection of uniform or varying sheet thickness, using a combination of sensors to prevent jams by adjusting the discharge process according to the sheet type and thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sheets with varying thickness are stacked on the sheet discharge tray, then the printing capability is improved, but sheet discharge jam occurs due to premature contact with the scanner
Solution Approach 1:
The controller performs preliminary action by determining the sheet type (uniform or varying thickness) before stacking sheets on the discharge tray. Based on this determination, it pre-configures the discharge control parameters to prevent jamming. For sheets with varying thickness, the controller limits the number of sheets to be discharged, ensuring that even though individual sheets may have different thicknesses, the total stack height remains within safe limits and does not contact the scanner.
Solution Approach 2:
The system dynamically adjusts the sheet discharge control based on the detected sheet type. When sheets with varying thickness are detected, the controller changes the discharge strategy from sensor-based height monitoring (for uniform sheets) to count-based limiting (for varying thickness sheets). This dynamic adaptation allows the system to handle different sheet types optimally, preventing jamming while maintaining printing versatility.
2Productivity
If the number of stackable sheets is increased to improve productivity, then sheet discharge jam occurs due to limited space between sheet discharger and scanner
Solution Approach 1:
The controller determines the sheet type before stacking and pre-calculates the appropriate discharge limit. For sheets with varying thickness, it applies a conservative discharge limit that ensures the total stack height will not exceed the safe threshold, even though this reduces the number of stackable sheets compared to uniform thickness sheets. This preliminary determination prevents jamming while maximizing the allowable stack size within spatial constraints.
Solution Approach 2:
The system changes the control parameter from continuous height monitoring (full sensor detection) to discrete count-based limiting when handling sheets with varying thickness. This parameter change allows the system to account for the uncertainty in individual sheet thickness by controlling the total number of sheets discharged, thereby maintaining reliable operation within the limited vertical space between the sheet discharger and scanner.
3Measurement precision
If full sensor detection is used to stop discharging, then uniform thickness sheets are handled correctly, but sheets with varying thickness cause jam before sensor detection
Solution Approach 1:
The system dynamically switches between two detection strategies based on sheet type: for uniform thickness sheets, it uses full sensor detection to monitor the actual stack height; for sheets with varying thickness, it switches to count-based limiting. This dynamic adaptation resolves the contradiction by applying the appropriate detection method for each sheet type, ensuring both measurement precision and reliability.
Solution Approach 2:
The controller acts as an intermediary that translates the physical property of sheet thickness variation into a control strategy change. It detects the sheet type and mediates between the full sensor detection system and the discharge mechanism, selecting the appropriate control mode. This intermediary function allows the system to handle both uniform and varying thickness sheets reliably, preventing jamming while maintaining accurate discharge control.
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 solution effectively prevents sheet discharge jams in printing operations involving sheets with varying thickness, reducing the time and effort required to resolve jams and allowing for safe stacking of sheets with non-uniform thickness, thereby enhancing the operational efficiency and reliability of the printing process.
Implementation Method 1
an upstream portion of a sheet discharge tray being tilted to extend downward in a direction of gravity
Data Source
AI summary
A printing apparatus includes: a sheet discharge tray having an upstream portion tilted to extend downward in a direction of gravity; an upper member limiting a height of a space above the sheet discharge tray; a full sensor configured to detect an upstream end of a top sheet of sheets stacked on the sheet discharge tray; a counter configured to count a number of the sheets discharged onto the sheet discharge tray; and a controller. The controller determines whether to stop discharging of the sheets to the sheet discharge tray, based on a detection result of the full sensor upon the sheets to be stacked on the sheet discharge tray including only sheets each with uniform thickness and based on a count value of the counter upon the sheets to be stacked on the sheet discharge tray including a sheet with thickness varying partly.