Patent Publication Number: US-2006012109-A1

Title: Paper sending mechanism with a dynamically adjustable paper-feeding angle

Description:
BACKGROUND OF THE INVENTION  
      1. Field of Invention  
      The invention relates to a paper sending mechanism and, in particular, to a paper sending mechanism that dynamically adjusts the paper-feeding angle according to the number of papers inside a paper tray.  
      2. Related Art  
      Most offices use a lot of papers for printing, copying or faxing various kinds of documents and letters. In generally, commonly seen business machines such as copiers require the feeding of papers for printing. The printing quality and operation efficiency are the focusing concerns of the manufacturers of business-related machines.  
      In these business machines, how to avoid paper jams and how to pick accurately single piece of paper are the important research directions in the development of paper transmission devices. Related techniques have been disclosed in, for example,  FIG. 1  shows an automatic paper-feeding roller pressure adjusting mechanism. As shown in  FIG. 1 , the mechanism is characterized in that a plate  110  is provided under a paper tray  100 . Both ends of the plate  110  are installed with a first spring  120  and a second spring  130  connected to the paper tray  100 . A supporting point  140  is provided in the middle section of the plate  110 . As the plate  110  functions as a lever and the first spring  120  and the second spring  130  deform, the pressure between the paper-separating roller and the paper-separating chip is adjusted to control the paper-feeding angle of the paper tray  100 .  
      The U.S. Pat. No. 4,212,456 uses a paper tray installed with an axis in the middle section under it. Thus, the paper tray can rotate relative to the printing device. An elastic plate is provided under the paper tray. A pressure spring is installed at the paper entrance in front of the paper tray. The paper-feeding angle is thus adjusted by the elastic plate and the pressure spring. The U.S. Pat. No. 5,718,424 has a paper-feeding roller and a rotatable pressure plate installed at the paper entrance of the paper tray. One end of the pressure plate is installed with an elastic device. As paper pushes the pressure plate that drives the elastic device, the paper-feeding roller and the pressure plate form different paper-feeding gaps.  
     SUMMARY OF THE INVENTION  
      The invention improves the action principles of the above-mentioned prior art. The specification provides a paper sending mechanism with a dynamically adjustable paper-feeding angle, which paper sending mechanism has fewer component devices, simpler and more direct actions, lower production costs, and a design for easier assembly and maintenance.  
      The disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle can be used in printers, fax machines, scanners, and multi-function peripherals (MFP). It comprises a paper tray, paper-feeding roller, a paper-separating plate, and a torsion spring. The paper tray can accommodate several pieces of paper for printing, and has a paper entrance. The bottom of the paper tray is extended out with a suspension arm that is pivotally connected to a printing device, so that the paper tray can rotate relative to the printing device. The paper-feeding roller and the paper-separating plate are installed and are adjacent to the paper entrance of the paper tray. The paper-separating plate picks up a piece of paper through the paper-feeding roller, and feeds it into the printing device. The torsion spring includes a first spring arm and a second spring arm. Due to an elastic force, the second spring arm has a specific angle with respect to the first spring arm. The first spring arm is connected to the printing device, and the second spring arm touches the bottom of the paper tray.  
      When the papers in the paper tray get fewer and fewer because of being used, the angle between the second spring arm and the first spring arm gradually increases, and thus the paper tray also rotates, by using the suspension arm as its center, with respect to the printing device. Therefore, if there are more papers inside the paper tray, its angle is flatter. If the papers inside the paper tray get fewer and fewer because of being used, then the second spring arm in touch with the paper tray experiences less weight from the papers, so that the angle between the first spring arm and the second spring arm increases to push the paper tray. In this case, the paper tray has a steeper paper-feeding angle, and is much easier for the paper therein to enter the paper-separating region.  
      The disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle uses a torsion spring, which does not require any other component to produce action and which is installed in a manner that is in direct contact with the bottom of the paper tray. Its action contact surface is more direct and complete. It can more rapidly and accurately react to the amount of papers inside the paper tray in order to dynamically adjust the paper-feeding angle. Thus, the invention can avoid incorrect paper picking. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will become more fully understood from the detailed description given hereinbelow illustration only, and thus are not limitative of the present invention, and wherein:  
       FIG. 1  is a schematic view of a conventional paper sending device;  
       FIG. 2  is a schematic view of the first action of the disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle; and  
       FIG. 3  is a schematic view of the second action of the disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle is shown in  FIGS. 2 and 3 . It can be used in printers, fax machines, scanners, and multi-function peripherals (MFP). The invention comprises a paper tray  10 , paper-feeding roller  20 , a torsion spring  30 , and a paper-separating plate  40 . The paper tray  10  accommodates several pieces of papers  60  for printing and has a paper entrance  11  for the paper to enter a printing device (not shown). The bottom of the paper tray  10  is extended out with a suspension arm  12  that is pivotally connected to the printing device, so that the paper tray  10  can rotate relative to the printing device. The paper-feeding roller  20  is covered with a rubber layer to increase the friction for picking paper  60 . The paper-feeding roller  20  is installed at the vicinity of the paper entrance of the paper tray  10 . The paper-separating plate  40  is installed at the vicinity of the paper entrance  11  of the paper tray  10 , corresponding to the paper-feeding roller  20  in order to pick papers  60  into the printing device. Another side of the paper-separating plate  40  is connected with an elastic device  50  for pushing the paper-separating plate  40 , so that the paper-separating plate  40  is in constant contact with the paper-feeding roller  20 . The torsion spring includes a first spring arm and a second spring arm. The first spring arm is in contact with the printing device and restricted by a stopper  80 . The second spring arm  32  is in touch with the bottom of the paper tray  10 . The first spring arm  31  and the second spring arm  32  have a specific relative angle  33 . There is not limitation on where the torsion spring  30  is installed.  FIG. 2  shows a preferred embodiment. An axis  70  is installed in the printing device for the installation of the suspension arm  12 , the paper-feeding roller  20 , and the torsion spring  30 . In fact, the axis  70  can be formed on the suspension arm for the installation of the torsion spring  30 . The invention does not limit the installation positions of the axis  70  and the torsion spring  30 .  
      With further reference to  FIG. 3 , as the papers  60  in the paper tray  10  get fewer and fewer as being used, the angle  33  between the second spring arm  32  and the first spring arm  31  gradually increases, thereby raising the paper tray  10 . The paper tray  10  thus rotates with respect to the printing device using the axis in connection with the suspension arm  12  as its center. The rotation angle of the paper tray  10  increases with the angle  33 . Therefore, if there is more papers  60  inside the paper tray  10 , the paper-feeding angle  95  between the paper tray  10  and the level surface  90  is flatter. If the papers  60  inside the paper tray  10  reduces with its usage, the second spring arm  32  in touch with the paper tray  10  experiences less weight from the papers  60 . The angle between the first spring arm  31  and the second spring arm  32  increases to push the paper tray  10 . In this case, the paper tray  10  has a steeper paper-feeding angle  95  with respect to the level surface  90 , easier for the papers  60  therein to enter the printing device.  
      The torsion spring  30  of the disclosed paper sending mechanism with a dynamically adjustable angle is in direct contact with the bottom of the paper tray  10 . Therefore, the torsion spring  30  can more rapidly and accurately react to the number of papers  60  stored inside the paper tray  10 . The paper-feeding angle  95  is thus dynamically adjusted to avoid incorrect paper-feeding.  
      Certain variations would be apparent to those skilled in the art, which variations are considered within the spirit and scope of the claimed invention.