Computer graphics processing and selective visual display system – Display peripheral interface input device – Cursor mark position control device
Reexamination Certificate
1998-04-01
2001-12-04
Chow, Dennis-Doon (Department: 2775)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Cursor mark position control device
C345S163000
Reexamination Certificate
active
06326951
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to a track ball, and more particularly to a track ball having an inner ball fitted in an outer hollow sphere.
BACKGROUND OF THE INVENTION
A track ball device is a tool for controlling a movement of the cursor, which includes therein a global object called track ball. A general track ball has a diameter of about 1.5-2.0 cm, and is used in a personal computer for functioning like a traditional mouse device.
As for the video games, the track ball generally has a larger diameter of about 10 cm. There are two types of video game track balls, one is a hollow structure and the other is a solid structure. The hollow track ball includes two hemispherical shells which have the advantage of light weight but present therebetween an untidy joint portion due to the combination thereof. Accordingly, the solid track ball is introduced to avoid the appearance of a joint seam. But, such a prior solid track ball has a drawback that the entire solid body is made of Acrylonitrile-Butadiene-Styrene (ABS), which is relatively heavy, not effective in material, and uneasy in operation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a track ball having an inner ball which can greatly reduce the weight of the track ball because the inner ball is made of a special material.
According to the present invention, a track ball device includes a body, and a track ball mounted on the body. The track ball has an outer hollow sphere and an inner ball fitted in the outer hollow sphere.
In accordance with an aspect of the present invention, the inner ball is immovably fixed in the outer hollow sphere.
In accordance with another aspect of the present invention, the inner ball is made of a polyurethane (PU) foam material.
Preferably, the track ball has a diameter ranged from 2 to 5 inches.
In accordance with another aspect of the present invention, the method for manufacturing a track ball includes the steps of a) providing an inner ball, b) providing a global mold, c) positioning the inner ball at a central portion of the global mold, and d) injecting a material into the global mold for encapsulating therein the inner ball to finally result in the track ball. Preferably, the injected material is an unsaturated polyester.
The method further includes the steps of e) injecting a hardening agent into the global mold to harden the unsaturated polyester, and f) placing the track ball in a ball miller to be polished, lustered and finely ground.
The present invention may best be understood through the following description with reference to the accompanying drawings, in which:
REFERENCES:
patent: 721462 (1903-02-01), Richards
patent: 2361348 (1944-10-01), Dickson et al.
patent: 3098658 (1963-07-01), Murphy
patent: 3177280 (1965-04-01), Ford et al.
patent: 3270108 (1966-08-01), Randolph
patent: 4454253 (1984-06-01), Murphy
patent: 4766194 (1988-08-01), Robertson
patent: 5029292 (1991-07-01), Zajicek
Chow Dennis-Doon
Knobbe Martens Olson & Bear LLP
Primax Electronics Ltd.
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