Belt Surface Resistance for Residual Image Control
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Solution Overview
Problem
Image forming apparatuses face challenges in preventing residual images and transfer failures due to residual potential on belt-type media, especially when the surface resistance of the belt is outside the optimal range, leading to inefficient discharge and increased costs from larger roller diameters required for downsizing and speed enhancement.
Innovation Solution
An image forming apparatus with a belt-like medium having a surface resistance between 1 × 10^10 Ω/□ and 5 × 10^12 Ω/□, where the conductive roller is positioned to ensure the decay time of the charge voltage matches the belt wrapping length and process speed, effectively managing charge distribution and discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diameter of the conductive spanned roller is configured to be relatively large to enhance discharging effect, then the discharging effect is improved, but the weight and belt perimeter increase, making the unit larger in size
Solution Approach 1:
The invention changes the surface resistance parameter of the belt-like medium from a conventional low-resistance material to a specific high-resistance range (1×10^10 to 5×10^12 Ω/□). This parameter change fundamentally alters the discharge mechanism, allowing effective charge attenuation without requiring large-diameter rollers, thus reducing weight and size while maintaining discharging effectiveness
Solution Approach 2:
Instead of using a large-diameter conductive roller to discharge charges through extended contact, the invention inverts the approach by using a high-surface-resistance belt material that naturally attenuates charges through its inherent properties during rotation, eliminating the need for oversized conductive rollers
2Reliability
If the surface resistance of the belt is relatively low to facilitate charge discharge, then the discharge is improved, but the charge distribution at the transfer nip is widened, increasing the electric field at void areas and causing image debris
Solution Approach 1:
The invention identifies and applies a specific surface resistance parameter range (1×10^10 to 5×10^12 Ω/□) that optimizes both charge discharge and image quality. This precise parameter control prevents charge migration that causes image debris while maintaining effective discharge capability, resolving the contradiction between discharge efficiency and image quality
3Object-generated harmful factors
If the surface resistance of the belt is relatively high to prevent charge migration and image debris, then image quality is improved, but the charge discharge becomes difficult and the electric field state becomes unstable
Solution Approach 1:
The invention determines an optimal surface resistance range (1×10^10 to 5×10^12 Ω/□) that balances two opposing requirements: high enough to prevent charge migration and image debris, but low enough to allow effective charge discharge. This precise parameter specification resolves the contradiction by finding the optimal middle ground
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 prevents residual images and transfer failures by ensuring efficient charge decay and discharge, maintaining image quality while allowing for downsizing and cost reduction by optimizing roller diameter and surface resistance.
Implementation Method 1
The attenuation of residual charge of the belt-type medium is performed when the belt-type medium comes into contact with an earthed conductive spanned roller during a rotary operation thereof
Implementation Method 2
The one or more primary transfer members are corresponding to the one or more image bearing members on a one-to-one basis, and are configured to sequentially transfer the one or more toner images formed on the one or more image bearing members onto the belt-like-shaped medium
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An image forming apparatus includes an image bearing member (20Y), supporting rollers (15,16), a belt-like-shaped medium (10), a primary transfer member (12Y), a secondary transfer member (5), and a grounded conductive roller. The image bearing member forms a toner image at a predetermined process speed. The belt-like shaped medium has a charge voltage. The primary transfer member sequentially transfers the toner image onto the belt-like-shaped medium and the secondary transfer member transfers the toner image onto a recording sheet (2). The conductive roller is arranged in contact with the belt-like shaped medium by a predetermined wrapping length. A relationship Tb < X/Vb is satisfied, where Tb is a decay time period in units of second in which the charge voltage of the belt-like shaped medium decays from approximately 200 volts to 200/e volts, where e is a base of natural logarithm, X is the predetermined wrapping length of the belt-like shaped medium against the conductive roller, and Vb is the predetermined process speed.