Printer

Abstract

A printer. The printer comprises a base having an incline surface for paper on which a depression is formed, a shaft disposed above the incline surface, an arm pivoted on the shaft, a pick-up roller disposed on the tip of the arm, and a free arm with one end pivoted on the arm and the other end free. When the paper on the incline surface runs out, the free arm is rotated and the free end enters and abuts the depression, whereby the arm is supported by the free arm to maintain an appropriate distance to the incline surface.

Description

BACKGROUND

The invention relates to a printer, and in particular to a printer with a pick-up roller protection mechanism.

FIG. 1a depicts a base of a conventional printer. FIG. 1b is a partially enlarged view of region A of FIG. 1a. A base 10 comprises an incline surface 12 on which a depression 14 is formed. The depression 14 can prevent the pick-up roller from contacting the incline surface 12 directly when paper thereon runs out. The direct contact of the pick-up roller and the incline surface can wear the pick-up roller, and even break the shaft of the pick-up roller. When no paper is loaded on the incline surface 12, the pick-up roller falls into the depression 14 and idles therein rather than contacting the incline surface directly. In such a structure, when little paper remains on the incline surface, the pick-up roller easily presses the paper into the depression 14, and an impression may occur on the paper.

Another pick-up roller protection mechanism is disclosed in U.S. Pat. No. 5,527,026 shown in FIGS. 2a and 2b. When paper is loaded on a pick plate 21, the pick-up roller 13 rotates and picks up paper. When paper on the pick plate 21 runs out, a roller 27 projecting from a groove on the pick plate 21 contacts and rotates with the pick-up roller 13 to avoid direct contact of the pick-up roller 13 and the pick plate 21.

SUMMARY

An embodiment of a printer of the invention comprises: a base having an incline surface for loading paper on which a depression is formed; a shaft disposed above the incline surface; an arm pivoted on the shaft; a pick-up roller disposed on the tip of the arm; and a free arm with one end pivoted on the arm and the other end free. When the paper on the incline surface runs out, the free arm is rotated and the free end enters and abuts the depression, whereby the arm is supported by the free arm to maintain an appropriate distance from the incline surface.

The free arm can be rotated by gravity or an elastic element disposed between the free arm and the arm, whereby the free end enters the depression. The elastic element can comprises a torsion spring.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1a depicts a base of a conventional printer;

FIG. 1b is a partially enlarged view of region A of FIG. 1a;

FIGS. 2a and 2b depict another pick-up roller protection mechanism of a conventional printer;

FIG. 3 is a perspective view of an embodiment of a printer;

FIG. 4 is an exploded view of FIG. 3;

FIG. 5 depicts the free arm pivoted on the arm;

FIG. 6 depicts the free arm detached from the arm;

FIGS. 7a to 11b depict the free arm preventing direct contact of the pick-up roller and the inclined surface;

FIG. 12 is a perspective view of another embodiment of the free arm;

FIG. 13 is an exploded view of FIG. 12; and

FIG. 14 is an enlarged view of the free arm of FIG. 13.

DETAILED DESCRIPTION

Referring to FIGS. 3 and 4, an embodiment of the printer comprises a base 100. An inclined surface 200 is disposed on the base 100. A shaft 300 is disposed above the inclined surface 200. An arm 400 is pivoted on the shaft 300. A pick-up roller 500 is disposed on the tip of the arm 400. The shaft 300 drives the transmission mechanism (not shown) in the arm 400 to rotate the pick-up roller 500. A free arm 600 is pivoted on the arm 400. Referring to FIGS. 5 and 6, a shaft element 620 is disposed on one end of the free arm 600. The shaft element 620 is inserted into a hole in the arm 400, whereby the free arm 600 is pivoted on the arm 400. The other end of the free arm 600 is released.

FIGS. 7a to 11b depict the free arm avoiding direct contact of the pick-up roller and the inclined surface.

In FIGS. 7a and 7b, when no paper is loaded on the inclined surface 200, the free arm 600 enters and abuts a depression 220 on the incline surface 200, whereby the arm 400 is supported to maintain an appropriate distance between the pick-up roller 500 and the incline surface 200 to prevent direct contact therebetween. When paper 7 is loaded on the incline surface 200, the free arm 600 is lifted by paper 7 and the pick-up roller 500 contacts and picks up the paper 7 as shown in FIGS. 8a and 8b. As the amount of the paper 7 is decreased gradually, the arm 400 is lowered and the free arm 600 rotates down as shown in FIGS. 9a and 9b. When only one piece of the paper 7 remains on the incline surface, the front of the paper 7 enters printing region and the rear end of the paper 7 is stretched as shown in FIGS. 10a and 10b. The arm 400 is lifted by the paper 7 to a specific height, and the free arm 600 is lifted by the arm 400. When the rear end of the paper 7 leaves the free arm 600 and still contacts the arm 400, the free arm 600 is rotated counterclockwise by gravity and enters the depression 220. When the paper 7 escapes from the arm 400 completely, the free arm 600 enters and abuts the depression 220, and the arm 400 is supported by the free arm 600 to maintain an appropriate distance from the incline surface 220 as shown in FIGS. 11a and 11b.

Accordingly, the free arm 600 maintains an appropriate distance between the pick-up roller 500 and the incline surface 220. As the depression 220 is not disposed immediately under the pick-up roller 500 and the free arm 600 exerts no force on the paper 7, no impression occurs on the paper 7.

Referring to FIGS. 12 and 13, a torsion spring 700 is disposed between the free arm 600 and the arm 400. One end of the torsion spring 700 is secured on the arm 400, and the other end thereof biases the free arm 600. Accordingly, when paper 7 runs out, the biasing force of the torsion spring 700 rotates the free arm 600 to increase the reliability of the free arm 600 entering the depression 220. In addition, the arm 400 comprises a shaft element 440, and the free arm 600 comprises a hole 640 in which the shaft element 440 is inserted. The free arm 600 is positioned on the arm 400 by a pin 800. Referring to FIG. 14, a post 680 disposed on the free arm 600 is used for positioning the torsion spring 700. Although a torsion spring 700 is used in this embodiment, it is not limited thereto. Other elastic elements, such as a expansion spring with one end on the arm 400 and the other end on the free arm 600, can also be used to ensure that the free arm enters the depression.

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Claims

1. A printer, comprising:

a base having an incline surface for paper on which a depression is formed;

a shaft disposed above the incline surface;

an arm pivoted on the shaft;

a pick-up roller disposed on the tip of the arm; and

a free arm with one end pivoted on the arm and the other end free, wherein when the paper on the incline surface runs out, the free arm is rotated and the free end enters and abuts the depression, whereby the arm is supported by the free arm to maintain an appropriate distance from the incline surface.

2. The printer as claimed in claim 1, wherein the free arm is rotated by gravity, whereby the free end enters the depression.

3. The printer as claimed in claim 1 further comprising an elastic element disposed between the arm and the free arm and biasing the free arm, wherein when the paper on the incline surface runs out, the free arm rotates and the free end enters the depression.

4. The printer as claimed in claim 3, wherein the elastic element comprises a torsion spring.

5. The printer as claimed in claim 3, wherein the elastic element comprises an expansion spring with one end disposed on the arm and the other end disposed on the free arm.

6. The printer as claimed in claim 4, wherein the free arm comprises a post on which the torsion spring is disposed.

7. The printer as claimed in claim 1, wherein the arm comprises a hole and the free arm comprises a shaft element inserted into the hole, whereby the free arm is pivoted on the arm.

8. The printer as claimed in claim 1, wherein the arm comprises a shaft element and the free arm comprises a hole into which the shaft element is inserted, whereby the free arm is pivoted on the arm.

9. The printer as claimed in claim 8 further comprising a pin connecting the shaft element and the hole.

10. The printer as claimed in claim 1, wherein the arm comprising a transmission mechanism driven by the shaft to rotate the pick-up roller to pick up the paper.