Selective Electrographic Printing with Variable Toner Particle Size
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Solution Overview
Problem
Electrographic printing techniques have not been practical for producing prints with a tactile feel using small size marking particles, as they lack the necessary relief and quality for applications like Braille or high-quality stationery, where raised information is desired.
Innovation Solution
The method involves selectively using larger marking particles in specific areas of the print image to create a tactile feel, building up layers of standard-sized toner particles to achieve a stack height of at least 20 μm, or using larger clear toner particles on top of smaller particles to achieve the desired raised texture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If small size marking particles (less than 8 μm) are used for electrographic printing, then image quality is improved, but the ability to produce tactile feel and raised information is lost
Solution Approach 1:
The patent applies local quality by using different particle sizes in different regions of the print. Small particles (less than 8 μm) are used in areas requiring high image quality, while large particles (8-15 μm or larger) are used in areas where tactile feel and raised information are needed. This spatial differentiation allows each region to have the optimal particle size for its specific function.
Solution Approach 2:
The patent segments the marking particle population into at least two distinct size groups: small particles for high-quality image areas and large particles for tactile/raised information areas. This segmentation enables the printing system to selectively apply different particle types to different regions, resolving the contradiction between image quality and tactile capability.
2Adaptability or versatility
If large marking particles (10-15 μm) are used to create tactile feel and raised information, then tactile capability is improved, but image quality deteriorates due to relief appearance
Solution Approach 1:
Large particles are applied locally only in regions where tactile feel is required, such as for raised information, Braille, or security features. The majority of the print image uses small particles to maintain high image quality. This localized application eliminates the relief appearance problem in standard image areas while preserving tactile capability where needed.
Solution Approach 2:
The patent divides the print area into zones requiring different particle sizes. Standard image areas receive small particles for quality, while specific zones requiring tactile feedback receive large particles. This segmentation allows the system to overcome the image quality deterioration caused by large particles by restricting their use to appropriate areas only.
3Manufacturing precision
If uniformly small marking particles are used throughout the print image, then high image quality is achieved, but raised information with tactile feel cannot be produced
Solution Approach 1:
The patent implements local quality by allowing small particles to dominate the overall print for high image quality, while permitting large particles to be used in specific local areas where tactile relief is required. This creates a heterogeneous particle distribution that simultaneously achieves high image quality and provides tactile feedback where needed.
Solution Approach 2:
The patent segments the particle application process into two streams: one using small particles for the main image body and another using large particles for raised information elements. This segmentation enables the coexistence of high image quality and tactile relief by assigning appropriate particle sizes to appropriate functional regions.
4Adaptability or versatility
If large marking particles are used to build up stack height for tactile feel, then raised information is achieved, but the process complexity increases compared to standard printing
Solution Approach 1:
The patent uses preliminary action by pre-separating marking particles into different size groups before the printing process. This pre-separation allows the printing system to selectively apply the appropriate particle size to each region without requiring complex real-time adjustments during printing, thereby reducing process complexity while maintaining the capability to produce raised information.
Solution Approach 2:
The patent extracts the tactile function from the general printing process by using a separate development process or dual-development system that specifically handles large particles for raised information areas. This extraction allows the main printing process to remain simple and focused on image quality, while a specialized subsystem handles the tactile relief function.
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 approach allows for the creation of high-quality prints with a distinct tactile feel, suitable for applications such as Braille, stationery, and security features, while maintaining the image quality of small particle prints.
Implementation Method 1
a charger for uniformly charging a photoconductive member
Implementation Method 2
discharging selected areas of the uniform charge to yield an image-wise electrostatic charge pattern by exposing the uniformly charged photoconductive member to actinic radiation
Implementation Method 3
the pigmented marking particles are given a charge, substantially opposite the charge pattern on the photoconductive member and brought into the vicinity of the photoconductive member so as to be attracted to the image-wise charge pattern
Implementation Method 4
A suitable electric field is applied to transfer the marking particles to the receiver member in the image-wise pattern to form the desired print image on the receiver member
Data Source
AI summary
Electrographic printing wherein raised information, with a distinct tactile feel, can be printed by electrographic techniques. Such electrographic printing comprises the steps of forming a desired print image, electrographically, on a receiver member utilizing standard size marking particles; and in an area of the formed print image, where desired tactile feel, raised information is to be formed, selectively forming such tactile feel, raised information utilizing marking particles of a substantially larger size than the standard size marking particles of the desired print image.