DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] The electrostatic transmission mechanism of the invention includes a feed roller and an electrostatic field generator. The electrostatic field generator generates a reaction on the feed roller and produces an electrostatic field on the roller surface. Therefore the feed roller can attract the media to be transported. Through the rotation of the feed roller, the media may be moved as desired. An electrostatic field may be generated by many methods. The following depicts one embodiment for elaboration of the invention.

[0017] Referring to FIG. 2, a feed roller 10 has its surface coated or taped with conductive wires 21. The conductive wires 21 are coated and covered by an insulation layer 22. Conductive wires 21a and 21b cross each other and connect to a positive pole and a negative pole (not shown in the drawing) of a power supply. The wiring configuration may be a band shape (as shown in FIG. 3A), a wave shape (as shown in FIG. 3B), or a saw shape (as shown in FIG. 3C). The wiring may be parallel with the spindle direction of the feed roller 10, or form an angle with the spindle direction. In principle, the conductive wires 21a and 21b must be crossed with each other to generate the electrostatic field on the surface of the feed roller 10. The intensity of the electrostatic field is controlled by different types and densities of the wiring configuration and different widths of insulation layer 22. Designs of the wiring configuration, in addition to considering the intensity of the electrostatic field, also depend on deploying environments, locations and utilization. And the intensity of the electrostatic field is also determined by the voltage difference output of the power supply.

[0018] When adopted on a printing middle frame as shown in FIG. 4, the feed rollers 11 and 12 have an electrostatic field and generate electrostatic force to attract a piece of paper 7 to their surfaces. Then the feed rollers 11 and 12 rotate to convey the paper 7. Such a design does not require that the paper is moved to a selected location behind the print head 2 as the discharging system of the conventional star wheel 6 does (comparing with FIG. 1C), so it does not need many intermediate transmission gears. As a result, the length of the printing middle frame may be shortened, and cost can be reduced. Noise generated by the intermediate transmission gears is also reduced. In addition, as the paper 7 is transported by a single feed roller 11 (12), paper crumpling can be avoided. Thus the paper 7 becomes flat and smooth. The gap G between the print head 2 and the paper 7 also may be shrunk (as shown in FIG. 5). As a result, printing quality may be improved (comparing with FIG. 1A).

[0019] By the same token, when deploying the invention on a paper discharging mechanism, the feed roller 12 with an electrostatic field attracts the paper 7 and discharges the printed paper 7. There is no press operation, as required by the star wheels 6. Hence the printed paper does not have the star wheel tracks that might otherwise occur when the star wheels 6 roll over the fresh printing data on the paper 7 (shown in FIGS. 1B and 6).

[0020] In addition, Referring to FIGS. 7A and 7B, the feed rollers 13 and 14 with static electricity generate a stretching force on the paper 7 and change the direction of paper movement. In other words, by deploying a roller seat 17 (as shown in FIG. 8) to encase and anchor the feed roller 14, and to form selected exposing areas on the feed roller 14, the feed roller 14 with static electricity can attract the paper 7. Then the rotating feed roller 14 can move the paper 7 to a selected location A, and the paper 7 leaves the feed roller 14. When the paper 7 reaches location B, the paper 7 bounces upwards due to its own tension. When the paper 7 reaches location C, it completely separates from the feed roller 14.

[0021] By means of the construction set forth above, the electrostatic transmission mechanism of the invention can generate static electricity on the feed roller through the electrostatic field generator for attracting and transporting the media. In addition, it provides the following functions:

[0022] 1. By employing the attraction of static electricity, the media on the printing middle frame is flat and smooth. The gap between the print head and the media may be reduced to improve printing quality.

[0023] 2. The length of the printing middle frame may be reduced to lower cost.

[0024] 3. The star wheel tracks produced by the star wheels in the paper discharging mechanism may be eliminated to improve printing quality.

[0025] 4. The media transporting mechanism requires fewer elements.

[0026] 5. The principle of attraction of static electricity of a single feed roller may be used for re-direction of the media without using multiple rollers.

[0027] 6. The intensity of the electrostatic field may be controlled by a single circuit, different configurations and density of wiring, and thickness of the insulation layer.

[0028] While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.