Image Forming Apparatus Charge Applying Part for Uniform Transfer
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Solution Overview
Problem
Image forming apparatuses face challenges in achieving uniform toner transfer intensity across the recording sheet, particularly with thick paper, leading to intensity differences and potential discharge issues due to varying transfer electric fields.
Innovation Solution
A charge applying part is positioned upstream of the transfer part to vary the charge on the recording medium according to its position in the transport direction, using a device with needle electrodes or conductive elements to apply a non-uniform charge, ensuring a consistent transfer electric field across the sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform charge is applied to the recording medium, then the charging process is simple, but the transfer electric field becomes non-uniform leading to intensity differences and discharge defects
Solution Approach 1:
The patent applies local quality by making the charge amount vary according to position on the recording medium. The charge applying part charges different regions of the recording medium with different charge amounts, specifically applying more charge to regions where the transfer electric field is weaker and less charge to regions where it is stronger, thereby achieving uniform transfer electric field characteristics across the entire recording medium.
2Productivity
If the transfer electric field is increased to improve transfer intensity, then transfer efficiency improves, but discharge defects occur due to excessive field strength in certain regions
Solution Approach 1:
The patent applies parameter changes by varying the charge amount parameter across different positions of the recording medium. By adjusting the charge amount according to position, the transfer electric field strength is optimized for each region, ensuring sufficient transfer efficiency in weaker field regions while preventing discharge defects in stronger field regions.
3Manufacturing precision
If the recording medium thickness is increased for better image quality, then image quality improves, but transfer uniformity deteriorates due to varying electric field penetration
Solution Approach 1:
The patent applies local quality by adapting the charge distribution to compensate for the effects of recording medium thickness. By applying non-uniform charging that varies by position, the system compensates for variations in electric field penetration through the recording medium, maintaining transfer uniformity even when using thicker recording media for improved image quality.
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 configuration enhances the uniformity of the transfer electric field, reducing intensity differences and discharge defects, particularly with thick paper, by adjusting the charge distribution to match the transfer electric field requirements.
Implementation Method 1
a charge applying part which charges the recording medium such that an amount of charge in the recording medium varies according to the position therein in a direction intersecting a recording-medium transport direction when the recording medium has reached the transfer part
Data Source
AI summary
An image forming apparatus includes an image carrier that carries a toner image; a transfer part that is disposed so as to be in contact with the image carrier and transfers the toner image carried by the image carrier to a recording medium; and a charge applying part that is disposed on an upstream side of the transfer part in a recording-medium transport direction and charges the recording medium such that an amount of charge in the recording medium varies according to the position therein in a direction intersecting a recording-medium transport direction when the recording medium has reached the transfer part.