Sheet Heater Temperature Gradient Control
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Solution Overview
Problem
Printers face issues with density unevenness due to high-temperature conveyance belts causing temperature gradients on sheets, leading to pigment movement and image quality deterioration.
Innovation Solution
The implementation of a sheet heater system with a preheater and ultraviolet irradiators that selectively heat the sheet, reducing temperature gradients and ink fluidity to prevent pigment movement, while maintaining a lower temperature for the second conveyance belt to minimize density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conveyance belt is heated to accelerate drying of the liquid, then the drying speed is improved, but the conveyance belt temperature increases causing density unevenness
Solution Approach 1:
The heating function is segmented from the conveyance belt to a separate heater that heats only the sheet. The conveyance belt is divided into a first conveyance belt (heated) and a second conveyance belt (cooled), allowing independent temperature control for each function.
Solution Approach 2:
A heater is introduced as an intermediary device between the conveyance belt and the sheet to transfer heat selectively to the sheet without heating the conveyance belt itself. This mediator enables precise thermal control of the sheet while maintaining belt temperature stability.
2Temperature
If the conveyance belt temperature is increased to improve drying efficiency, then the drying performance is improved, but temperature gradients on the sheet cause pigment movement
Solution Approach 1:
The heating is applied locally to the sheet surface rather than uniformly to the entire conveyance belt. The heater targets specific regions of the sheet, creating localized temperature zones that dry the liquid without generating excessive temperature gradients that would move pigments.
Solution Approach 2:
The temperature parameter is changed and controlled independently for the sheet and the conveyance belt. The sheet temperature is increased for drying while the belt temperature is maintained at a lower, stable level, preventing pigment movement caused by belt heat.
3Productivity
If the conveyance belt is circulated immediately after heating to maintain productivity, then the production efficiency is improved, but the high-temperature belt causes density unevenness on subsequent sheets
Solution Approach 1:
The conveyance system is segmented into two separate belts with different temperature functions. The first conveyance belt handles heated sheets for drying, while the second conveyance belt handles cooled sheets for subsequent processing, allowing continuous operation without temperature-related quality issues.
Solution Approach 2:
The sheet is pre-heated by the heater before contacting the conveyance belt. This preliminary heating action completes the drying process before the sheet enters the conveyance belt, eliminating the need to heat the belt itself and preventing temperature-related density unevenness during conveyance.
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 effectively reduces density unevenness and improves image quality by controlling ink fluidity and pigment movement, ensuring consistent color density across the sheet.
Implementation Method 1
a preheater configured to heat the sheet upstream of the second conveyance belt
Implementation Method 2
a heating unit including a plurality of ultraviolet irradiators that irradiate the sheet conveyed by the first conveyance belt
Implementation Method 3
The printer includes a heater to heat the sheet on which the liquid is applied to accelerate drying of the liquid applied on the sheet
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A sheet heater (500) includes a first conveyance belt (511) configured to convey a sheet on which a liquid has been discharged in a conveyance direction, a heating unit (502) facing the first conveyance belt (511), the heating unit (502) configured to heat the sheet conveyed by the first conveyance belt (511), and a second conveyance belt (411) disposed upstream of the first conveyance belt (511) in the conveyance direction, the second conveyance belt (411) configured to convey the sheet to the first conveyance belt (511). A surface temperature of the second conveyance belt (411) is lower than a surface temperature of the first conveyance belt (511) when the first conveyance belt (511) and the second conveyance belt (411) convey the sheet.