BACKGROUND
The invention relates to a printer, and in particular to a printer having an idle wheel contacting the pick-up roller when no paper is loaded on a pick plate to avoid direct contact between the pick-up roller and the pick plate.
FIG. 1 depicts a pick plate of a conventional printer. FIG. 2 is an enlarged view of region A of FIG. 1. In a conventional printer, a pick-up roller 20 continues rotating and may contact the pick plate 10 directly when paper on the pick plate 10 runs out and the print job is not finished. Considerable friction, occurs and may damage the pick-up roller 20, and even deform or break the shaft of the pick-up roller 20. A depression 15 is usually formed on the pick plate 10 as shown in FIG. 2 to avoid this. When paper runs out, the pick-up roller 20 enters the depression 15 and idles therein rather than contacting the pick plate 10 directly.
When little paper remains on the pick plate 10, the remaining paper is easily pressed to the depression 15 by the pick-up roller 20. A pressed mark may occur on the paper and influencing print quality particularly for certain high quality paper, such as photo print paper.
SUMMARY
An exemplary embodiment of a printer with an idle wheel comprises: a pick plate having a loading surface on which paper is loaded; a pick-up roller disposed above the pick plate; and at least one idle wheel disposed on the pick plate and positioned under the pick-up roller. When no paper is loaded on the pick plate, the pick-up roller contacts and rotates the idle wheel to avoid direct contact between the pick-up roller and the pick plate. The axis of the idle wheel is perpendicular to the axis of the pick-up roller. An appropriate distance is maintained between the idle wheel and loading surface.
The printer further comprises a pad attached to the idle wheel. The pick-up roller contacts the idle wheel via the pad. The pad can be made of rubber.
The printer further comprises a friction element disposed between the idle wheel and the pick plate. The pick-up roller overcomes the friction between the friction element and the idle wheel to rotate the idle wheel. The friction element can be annular.
The printer further comprises a coupler disposed under the pick plate. The idle wheel is rotatably secured to the pick plate by the coupler.
In some embodiments, the idle wheel has a hook which engages a hole in the pick plate, whereby the idle wheel is rotatably secured on the pick plate.
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. 1 is a schematic view of a pick plate of a conventional printer;
FIG. 2 is an enlarged view of region A of FIG. 1;
FIG. 3 is a schematic view of a printer of the invention;
FIG. 4 is an exploded view of a printer of FIG. 3;
FIGS. 5 and 6 are schematic views of the idle wheel of the invention;
FIG. 7 is a cross section of the idle wheel joined with the pick plate of the invention;
FIG. 8 is an enlarged view of region B of FIG. 7;
FIG. 9 depicts another embodiment of the idle wheel of the invention;
FIG. 10 is an exploded view of another embodiment of the printer of the invention; and
FIG. 11 depicts a pick plate with two idle wheel of the invention.
DETAILED DESCRIPTION
Referring to FIG. 3, a printer 1000 comprises a pick plate 100, a pick-up roller 200 and an idle wheel 300. The idle wheel 300 is disposed on the pick plate 100. When paper on the pick plate 100 runs out, the pick-up roller 200 contacts the idle wheel 300 rather than the pick plate 100 directly. The axis of the idle wheel 300 is perpendicular to the axis of the pick-up roller 200.
When paper on the pick plate 100 runs out and a print job is not finished, the pick-up roller 200 contacts and rotates the idle wheel 300 in the direction shown by the arrow in FIG. 3.
Referring to FIG. 4, a depression 120 is formed on the pick plate 100 to accommodate the idle wheel 300. A friction element 400 is disposed between the idle wheel 300 and the depression 120. A pad 500 is disposed on the idle wheel 300. In this embodiment, the idle wheel 300 is rotatably secured in the depression 120 via a wheel (coupler) 600 disposed under the pick plate 100. FIGS. 5 and 6 depict the idle wheel 300 joined with the wheel 600. The wheel 600 has a shaft 620, and the idle wheel 300 has a bore 320. The shaft 620 extends through a through hole 122 of the depression 120 and is inserted into the bore 320, whereby the idle wheel 300 is rotatably secured in the depression 120.
Referring to FIG. 7, the friction element 400 is annular and disposed between the idle wheel 300 and the depression 120. The idle wheel 300 has a flange 340 abutting the friction element 400. When paper is loaded on the pick plate 100, friction from the friction element 400 brakes the idle wheel 300. When the last piece of paper is picked, the pick-up roller 200 contacts the idle wheel 300 directly, and torque from the pick-up roller 200 enables the idle wheel 300 to overcome the friction and rotate.
Referring to FIG. 8, the idle wheel 300 maintains an appropriate distance D from the loading surface of the pick plate 100. The edge of the pad 500 can be curved to avoid pressed mark on paper. The smaller the distance D and the more smooth the curved edge of the pad 500, the fewer marks are on the paper. The pad 500 can be made of soft material, such as rubber, and can be attached to the idle wheel 300 or integrally formed with the idle wheel 300.
FIG. 9 shows another embodiment of the idle wheel 300′. A pair of hooks 360 is disposed on the back of the idle wheel 300′. The hooks 360 extend through the through hole 122 and engage the back of the pick plate 100, whereby the idle wheel 300′ is rotatably secured in the depression 120. FIG. 10 depicts the idle wheel 300′ assembled with the friction element 400 and the pad 500. In this embodiment, the wheel 600 is not used, and the element number is thus reduced.
Two idle wheels 300 can also be disposed on the pick plate 100 and positioned under two sides of the pick-up roller 200 as shown in FIG. 11. Both idle wheel 300 can be secured by wheels 600 or hooks 360.
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.
Patent Application
20060267266
