Browse Prior Art Database

Improved method of fabricating banknote path components

IP.com Disclosure Number: IPCOM000248806D
Publication Date: 2017-Jan-12
Document File: 5 page(s) / 196K

Publishing Venue

The IP.com Prior Art Database

Abstract

In this white paper, a method is proposed to fabricate a banknote path for banknote validators. Current banknote validators use two shot injection molding, which requires two separate injection molding steps, and molds for fabrication of opaque and transparent parts of a banknote path. The proposed method here eliminates the need for the injection molding step and the mold for the transparent part by using a transparent film to replace the transparent mold around which the opaque part of the banknote path can be injection molded.

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Publication

Title – Improved method of fabricating banknote path components

Abstract

In this white paper, a method is proposed to fabricate a banknote path for

banknote validators. Current banknote validators use two shot injection

molding, which requires two separate injection molding steps, and molds for fabrication of opaque and transparent parts of a banknote path. The proposed

method here eliminates the need for the injection molding step and the mold

for the transparent part by using a transparent film to replace the transparent

mold around which the opaque part of the banknote path can be injection

molded.

Problem description

The construction of a banknote processing device requires a structure through

which a banknote can be transported. In order to provide reliable handling of

banknotes that are in poor condition, it is desirable to eliminate rough surfaces

and steps within these structures.

A practical approach is to use a banknote path fabricated in one piece by

injection molding. Since the universal use of optical recognition sensors requires

that, at least some part of the banknote path is transparent, early examples of

banknote validator paths were made from transparent plastics such as polycarbonate.

The use of transparent materials in the banknote path may allow unwanted light

from external sources (i.e.: sunshine or cross talk from sensors) to appear as a

noise source limiting the performance of the product. This deficiency has been

addressed in many different ways. For example, a transparent insert

surrounded by opaque materials may be used. However, this solution requires tighter tolerance controls as assembly could introduce rough or uneven surfaces

in the banknote path.

The current state of the art is to use a “two-shot” molding process. In this

process either the opaque main body or clear window of the banknote path

housing is molded first, and the resulting part is then moved to a second tooling

cavity where a second molding cycle completes the part in a different material.

This provides a part with perfectly smooth transitions between two different

materials. Thus optimal optical performance is possible while maintaining a

smooth banknote path using high volume production processes.

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Figure 1. Images of opaque external frame and transparent window

Figure 1 shows a banknote path formed by molding an opaque outer frame (1).

This outer frame (1) is then loaded into a second mold tool and clear windows

are formed with the geometry shown in (2). It is important to understand that the window (2) is formed in situ inside the outer frame (1). There is no post

forming assembly process. Extra forms are required to form the function of

“runners” are required to allow clear material to reach all the required areas

during injection molding. These features constrain the part design and can

introduce unwanted optical crosstalk.

While this construction has proven to be highly effective for mass production,

there are some process li...