BACKGROUND
1. Technical Field
The present disclosure relates to a printer and a paper reversing assembly thereof.
2. Description of Related Art
Referring to FIG. 1, many printers 100 with a duplex or two-sides printing function have an input roller 10, a printing roller 20, a paper reversing assembly 30, a paper tray 40 and an inkjet nozzle 50. The input roller 10, the printing roller 20 and the paper reversing assembly 30 can be driven by the same motor. When the printing roller 20 is rotated clockwise by the motor, the rollers of the paper reversing assembly 30 are unmoving; when the motor reverses and the printing roller 20 rotates counterclockwise, the rollers of the paper reversing assembly 30 are also driven to rotate, in the directions indicated in FIG. 1.
In implementing two-sides printing, the input roller 10 rotates to carry a piece of paper from the paper tray 40 to the printing roller 20, with a first side upward and its opposed side (which is named the second side hereinafter) unavailable to the printer 100. Then, driven by the rotation of the printing roller 20, the paper is moved to a location underneath the inkjet nozzle 50 to be printed on its first side, as the first side is upward. After the printing is over, the motor reverses and drives the printing roller 20 to rotate counterclockwise, sending the paper backward into the reversing assembly 30 to be turned upside down.
Once the paper has been turned upside down by the reversing assembly 30, it is pushed out of the reversing assembly 30, while its front portion reaches the printing roller 20 and the second side is facing up then. At that moment, the motor reverses again, switching the printing roller 20 back to rotate clockwise, and carrying the paper to the inkjet nozzle 50 to be printed on its second side. Meanwhile, the rollers of the paper reversing assembly 30 are still.
However, the aforesaid printer 100 has the following problem: when the reversing of the paper is finished, its front portion reaches the printing roller 20 while its rear portion is still inside the reversing assembly 30. Since the reversing assembly 30 has stopped rotating, the rear portion of the paper is trapped between the lowest roller of the reversing assembly 30 and its corresponding auxiliary roller 300. Under these circumstances, the paper is pulled out by the force provided by the rotation of the printing roller 20 while the lowest roller is still, and the still roller will block the moving of the paper. Thus, not only will ugly indentations be made on the paper, but also the printed image may be blurred since the transmission of the paper is unsteady.
BRIEF DESCRIPTION OF THE DRAWINGS
The components of the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments of a printer and a paper reversing assembly thereof. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views.
FIG. 1 is a schematic view of the structure of a conventional printer.
FIG. 2 is a schematic view of the structure of a printer of the present disclosure.
FIG. 3 is an exploded view of a roller of a paper reversing assembly of the printer of the present disclosure.
FIG. 4 is an exploded view of the roller from another aspect.
FIG. 5 is a cross-sectional view of the roller mechanism of the paper reversing assembly.
FIG. 6 is a cross-sectional view of the paper reversing assembly indicating its motion.
FIG. 7 is a cross-sectional view of the paper reversing assembly of the present disclosure.
DETAILED DESCRIPTION
The present disclosure is related to a printer and a paper reversing assembly thereof, more particular to an improved paper reversing assembly which can replace the paper reversing assembly 30 of the conventional printer 100 shown in FIG. 1.
FIG. 2 is a schematic view of a printer 100a, according to an exemplary embodiment of the present disclosure. The printer 100a includes an input roller 10, a printing roller 20, a paper reversing assembly 30a, an paper tray 40 and an inkjet nozzle 50. The paper reversing assembly 30a includes a first roller 301, a second roller 302 and a third roller 303. One or more motors (not shown) are configured for driving the input roller 10, the printing roller 20, and the aforesaid rollers 301-303.
In this embodiment, the paper entry point into the paper reversing assembly 30a adjacent to the first roller 301 is defined as the paper-in access; and the paper exit point from the paper reversing assembly 30a adjacent to the third roller 303 is defined as the paper-out portion.
In implementing the printing of both sides of a piece of paper, the input roller 10 and the printing roller 20 rotate clockwise as indicated, and the rollers 301-303 of the paper reversing assembly 30a do not move then. Then, once the paper is required to be turned upside down, the printing roller 20 rotates counterclockwise to send the paper backward into the reversing assembly 30a. At this time, the first roller 301 and the third roller 303 rotate counterclockwise and the second roller 302 rotates clockwise as indicated. The first roller 301, the second roller 302 and the third roller 303 cooperate with their corresponding auxiliary rollers 300 in handling the paper. The paper is turned upside down thereby.
The rollers 301-303 have the same structure in the embodiment. FIGS. 3, 4 and 5 will show one of the rollers 301-303 alone for clearly illustrating such structure. Meanwhile, any other components of the printer 100a will not be shown in FIGS. 3, 4 and 5, since the structure of the rollers 301-303 are the main improvement of the printer 100a.
Referring to FIGS. 3 and 4, the roller includes a driving member 31, several balls 32 and a paper roller 33. The balls 32 are made of a material of metal, which is preferably steel. One end of the driving member 31 communicates with a driving machine 60, and the driving machine 60 is driven by the motor (not shown). The driving member 31 includes a shaft 311 and a tri-lobular wheel 312, wherein the wheel 312 is fixed on the middle of the shaft 311 and has several lobes 3121 radially extending from one side of it. The lobes 3121 are spaced from each other, while each of the lobes 3121 further includes a curved surface at a first side and a substantially flat surface 3122 at an opposing second side.
The paper roller 33 includes a shaft body 331 and at least one rolling wheel 334, wherein the rolling wheel 334 may be made of, but is not limited to, rubber. A recess 332 is defined in an end face on each end of the shaft body 331. Several concave portions 333 are recessed in an internal circumferential surface of the shaft body 331 in the recess 332. The lobes 3121 of the driving member 31 are for engagingly received in the recess 332.
Referring to FIG. 5, a cross-sectional view of the roller is shown. Each of the concave portions 333 includes a first surface 3331 and a second surface 3332. The first surface 3331 is tangentially adjoining to the internal circumferential surface of the recess 332, and the second surface 3332 is steeply inclined to the internal circumferential surface. Several spaces 34 are defined, while each space 34 is defined by a flat surface 3122 of one lobe 3121 and a curved surface of another lobe 3121, with limitation of the internal circumferential sidewall of the recess 332. The balls 32 are movably contained in each space 34. Each of the balls 32 has their camber matching the second surface 3332 of the corresponding concave portion 333, thus for being engagingly received in.
Referring to FIGS. 5-7, when the driving member 31 rotates counterclockwise as a predefined rotating direction, each ball 32 is pushed by the substantially flat surface 3122 of the corresponding lobe 3121 and is retained by the second surface 3332 of one corresponding concave portion 333, as shown in FIG. 5 and FIG. 6. The balls 32 are trapped between the driving member 31 and the paper roller 33, therefore enabling the paper roller 33 to rotate with the driving member 31. The wheel 312 drives the paper roller 33 by means of the balls 32, making the rolling wheel 334 and its corresponding auxiliary roller (shown in FIG. 2) cooperate to reverse the paper.
Referring to FIG. 2, when the paper has reversed, the motor reverses and the printing roller 20 rotates clockwise. The assembly of the motor and the driving machine 60 allows the motor to drive the driving machine 60 when the motor is in a forward direction, and not to drive the driving machine 60 when the motor is reversed. Thus, the driving member 31 will stop rotating when the printing roller 20 rotates clockwise.
Referring to FIGS. 6-7 when referring to FIG. 2, the front portion of the reversed paper is moved to the inkjet nozzle 50 by the printing roller 20, as the rear portion of the paper is still between the third roller 303 and its corresponding auxiliary roller. Since the paper reversing assembly 30a does not challenge or fight the friction which exists between the rear portion of the paper and the third roller 303, a pulling force F produced by the printing roller 20 carries the paper forward and therefore rotates the third roller 303, smoothly drawing out the paper leaving the paper reversing assembly 30a, and preventing ugly indentations on the paper and avoiding bad printing quality. The pulling force is bigger than a maximum static friction force between the paper and the third roller 303 and acts as the force F as shown in FIG. 6.
In another embodiment, the paper reversing assembly 30a has only one roller of the aforesaid structure, with the other rollers being conventional.
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure.
Patent Application
20130026704
