Patent Publication Number: US-11648567-B2

Title: Automatic shredder having paper pressing mechanism

Description:
TECHNICAL FIELD 
     The invention relates, in general, to the field of automatic paper shredders and, in particular, to an automatic paper shredder having a paper pressing mechanism. 
     DESCRIPTION OF RELATED ART 
     Existing shredders with an automatic paper feed function typically include a paper pressing mechanism, a paper feed mechanism, a paper shredding mechanism and a driving mechanism which are mounted on a frame. A paper inlet is formed in a base plate located in a paper placement area. The paper shredding mechanism is located below the paper placement area and corresponds to the paper inlet in position. The paper feed mechanism is mounted at the paper inlet, folds paper along the paper inlet after the paper is pressed by the paper pressing mechanism, and conveys the folded paper to the paper shredding mechanism. The paper shredding mechanism shreds the paper, and the driving mechanism drives the paper feed mechanism and the paper shredding mechanism to operate. 
     The paper pressing mechanism includes a cover plate, a pressing plate flexibly mounted on the inner side of the cover plate, an elastic component mounted between the cover plate and the pressing plate, and a work chamber. The pressing plate is driven by the cover plate to move downwards to press against the paper under the effect of the elastic component. When such paper pressing mechanism is opened, the pressing plate will stretch out with respect to the cover plate, so that the size is large, and the appearance is affected. On the other hand, because the elastic component is arranged between the cover plate and the pressing plate, users have to overcome the elastic force of the elastic components to press the cover plate downwards, so that operation is difficult. In addition, if the cover plate fails to be completely closed or comes loose when needing to be closed to shield the paper placement area, the pressing plate will not be able to press the paper, or the pressing plate may eject the cover plate open during paper shredding, thus resulting in an accident and a shutdown. 
     BRIEF SUMMARY OF THE INVENTION 
     The defects of the prior art can be overcome by providing an automatic shredder having a paper pressing mechanism to solve the problems of unreasonable structure, inconvenient operation and insufficient paper pressing force of paper pressing structures. 
     To that end, the invention discloses a paper pressing mechanism for an automatic shredder, comprising a cutting mechanism, an upper shredder cover, a lower shredder cover, a paper support box, a paper pressing plate, a cover plate, a spindle and two spindle holders. The upper shredder cover is vertically and fixedly connected to the lower shredder cover. The paper support box is concavely disposed above the lower shredder cover to form an accommodating cavity for accommodating a stack of to-be-shredded paper. Fixed ends of the paper pressing plate and the cover plate are disposed around the spindle, so that free ends of the paper pressing plate and the cover plate are able to rotate coaxially. Two ends of the spindle are respectively disposed in the two spindle holders, so that the spindle is able to rotate. The two spindle holders are fixedly connected to the upper shredder cover to fixedly connect the cover plate and the paper pressing plate to the upper shredder cover. The paper pressing plate is disposed below the cover plate and is used for pressing the stack of to-be-shredded paper placed on the paper support box when a user closes the cover plate. 
     Furthermore, the paper pressing mechanism further has at least one limiting assembly including a positioning aperture, a positioning column, an elastic component and a stop component. 
     The positioning aperture is formed in the paper pressing plate. The positioning column matches the positioning aperture in position and has an end fixed to an inner side of the cover plate and an end penetrating through the positioning aperture. The stop component is connected to the end, away from the cover plate, of the positioning column and has a peripheral size greater than the diameter of the positioning aperture, so that the free end of the paper pressing plate is able to move between the two ends of the positioning column. The elastic component has an end fixed to a lower surface of the paper pressing plate and an end fixed to the spindle. When the user opens the cover plate, the stop component drives the paper pressing plate to turn upwards along the positioning column, and the elastic component is in a stretched state. When the user closes the cover plate, the elastic component contracts to automatically drive the paper pressing plate to turn downwards along the positioning column to enable the paper pressing plate to press against an upper surface of the stack of to-be-shredded paper, and the elastic component is in a contracted state. 
     The paper pressing mechanism may include two limiting assemblies having two positioning apertures, two positioning columns, two elastic components and two stop components. The two positioning apertures are symmetrically formed in the paper pressing plate. The two positioning columns have one ends symmetrically disposed on the inner side of the cover plate and the other ends respectively penetrating through the two positioning apertures and matching the two positioning apertures in position. The two stop components are respectively connected to the ends, away from the cover plate, of the two positioning columns and have peripheral sizes corresponding to the diameters of the two positioning apertures. The two elastic components have one ends fixed to the lower surface of the paper pressing plate and the other ends connected to the spindle in a hooked manner. 
     The elastic component is a tension spring having an end fixedly connected to an elastic component holder on the lower surface of paper pressing plate and the other end connected to the spindle in a hooked manner. When the number of the tension springs is two or more, the distances from joints of one ends of the plurality of tension springs and the elastic component holders to the spindle are equal, and the distances from the joints of one ends of the plurality of tension springs and the elastic component holders to the lower surface of the paper pressing plate are also equal, so that tensile forces applied to different positions of the paper pressing plate by the tension springs are uniform. The positioning aperture can be linear, oval or oblong. Long edges of the positioning aperture are perpendicular to the long axis of the spindle. The positioning column and the cover plate are manufactured integrally. The stop component is a screw, a nut, a bolt, a clamping pin, a positioning pin, or a stop pin. Furthermore, the paper pressing mechanism further includes at least one paper pick-up roller set including an upper paper pick-up roller and a lower paper pick-up roller. 
     The upper paper pick-up roller is fixed between two upper paper pick-up roller seats at a lower end of the paper pressing plate through an upper paper pick-up roller spindle. The lower paper pick-up roller is fixed to two sides of the lower shredder cover or between two lower paper pick-up roller seats at a lower end of the paper support box through a lower paper pick-up roller spindle. The lower paper pick-up roller partially protrudes out of an upper surface of the paper support box and corresponds to the upper paper pick-up roller in position, so that when the user closes the cover plate, the upper paper pick-up roller on the paper pressing plate presses against the stack of to-be-shredded paper on the paper support box and coordinates with the lower paper pick-up roller to enable one or more bottom pieces of paper in the stack of to-be-shredded paper to enter a paper inlet in the paper support box. The paper pressing mechanism has one paper pick-up roller set, in which the upper paper pick-up roller is located on a middle section of an inner side of the paper pressing plate, and the lower paper pick-up roller set is located on a middle section of one side of the paper inlet in the paper support box and corresponds to the upper paper pick-up roller in position. The paper pressing mechanism includes two paper pick-up roller sets which are symmetrically distributed on the inner side of the paper pressing plate and on one side of the paper inlet in the paper support box, respectively. The upper paper pick-up roller spindle is parallel to the lower surface of the paper pressing plate, and the lower paper pick-up roller spindle is parallel to the upper surface of the paper support box. The paper pressing mechanism further includes two torsion springs which are separately disposed around the two ends of the spindle and are respectively arranged in the two spindle holders at the two ends of the spindle to realize the rotation of the spindle. 
     The invention further discloses an automatic shredder, comprising a paper pressing structure, an upper shredder cover, a lower shredder cover, a paper support box, a shredder cover, a paper pressing base plate, a base plate spindle, big pressing plate torsion springs, a pressing plate spindle, a big pressing plate, two spindle torsion springs, two base plate spindle holders and two pressing plate spindle holders. The upper shredder cover is vertically and fixedly connected to the lower shredder cover. The paper support box is concavely disposed above the lower shredder cover to form an accommodating cavity for accommodating a stack of to-be-shredded paper. The shredder cover is connected to one end of the upper shredder cover through a pivot and is used for opening or closing the shredder. 
     One end of the paper pressing base plate is fixedly connected to the base plate spindle. The two spindle torsion springs are separately disposed around two ends of the base plate spindle and are respectively arranged in the two base plate spindle holders at the two ends of the base plate spindle, so that the base plate spindle is able to rotate to drive the paper pressing base plate to rotate. The two base plate spindle holders are fixedly connected to an inner side of the shredder cover to fixedly connect the paper pressing base plate to the inner side of the shredder cover. The two big pressing plate torsion springs are separately disposed around two ends of the pressing plate spindle and are respectively arranged in the two pressing plate spindle holders at the two ends of the pressing plate spindle, so that the pressing plate spindle is able to rotate to drive the big pressing plate to rotate. 
     The big pressing plate is rotatably connected to the paper pressing base plate from below through the pressing plate spindle and is used to pressing the stack of to-be-shredded paper placed on the paper support box when a user closes the shredder cover. The base plate spindle is disposed away from a pivot joint of the shredder cover and the upper shredder cover. The paper pressing structure further includes at least one paper pick-up roller set including an upper paper pick-up roller and a lower paper pick-up roller. The upper paper pick-up roller is fixed between two upper paper pick-up roller seats at the end, away from the base plate spindle, of the paper pressing base plate through an upper paper pick-up roller spindle. The lower paper pick-up roller is fixed to two sides of the lower shredder cover or between two lower paper pick-up roller spindle holders at a lower end of the paper support box through a lower paper pick-up roller spindle. The lower paper pick-up roller partially protrudes out of an upper surface of the paper support box and corresponds to the upper paper pick-up roller in position, so that when the user closes the cover plate, the upper paper pick-up roller on the paper pressing base plate presses against the stack of to-be-shredded paper on the paper support box and coordinates with the lower paper pick-up roller to enable one or more bottom pieces of paper in the stack of to-be-shredded paper to enter a paper inlet in the paper support box. 
     Furthermore, a paper pressing strip is disposed at the end, away from the base plate spindle, of the paper pressing base plate, is integrated with the paper pressing base plate, and is used for pressing a few pieces of to-be-shredded paper on the paper support box to the upper surface of the paper support box. The big pressing plate includes a big connecting plate and a big paper pressing plate, and the big paper pressing plate is, when the paper pressing base plate is naturally released, attached to the upper surface of the paper support box to press the stack of to-be-shredded paper to the upper surface of the paper support box. A first through-aperture is formed in the big paper pressing plate and matches a travel switch, partially upward protruding out of the paper support box, in position, so that when the stack of to-be-shredded paper on the paper support box is about to be completely shredded or has been completely shredded, the travel switch can be received in the first through-aperture and can feed back the paper shredding condition in time. In some embodiments, an angle between the big connecting plate and the big paper pressing plate is greater than or equal to 90 degrees. In other embodiments, the big connecting plate and the big paper pressing plate are manufactured integrally. 
     Moreover, the big pressing plate is divided into a plurality of small pressing plates each including a small connecting plate and a small paper pressing plate, and each small paper pressing plate is, when the paper pressing base plate is naturally released, attached to the upper surface of the paper support box to press the stack of to-be-shredded paper to the upper surface of the paper support box. When the pressing plate spindle is of an integrated structure, the small connecting plates of the plurality of small pressing plates are fixedly connected to the pressing plate spindle, and are fixedly connected to the paper pressing base plate through the big pressing plate torsion springs and the pressing plate spindle holders at the two ends of the pressing plate spindle. Alternately, when the pressing plate spindle is divided into a plurality of small pressing plate spindles, the number of the small pressing plate spindles is equal to that of the small pressing plates, the small connecting plates of the plurality of small pressing plates are fixedly connected to the plurality of small pressing plate spindles respectively, and are fixedly connected to the paper pressing base plate through small pressing plate torsion springs and small pressing plate spindle holders at two ends of the small pressing plate spindles. 
     Additionally, a second through-aperture is formed in the small paper pressing plate, located in a middle, of the plurality of small paper pressing plates and matches a travel switch, partially upward protruding out of the paper support box, in position, so that when the stack of to-be-shredded paper on the paper support box is about to be completely shredded or has been completely shredded, the travel switch can be received in the second through-aperture and can feed back the paper shredding condition in real time. In some embodiments, angles between the small connecting plates and the small paper pressing plates are equal and are greater than or equal to 90 degrees. In other embodiments, each small connecting plate and the corresponding small paper pressing plate are manufactured integrally. 
     By adoption of the above solutions, the embodiments of the invention have the following advantages and beneficial effects compared with the prior art. First, according to the paper pressing mechanism for an automatic shredder, through the cooperation of the positioning column on the inner side of the cover plate and the positioning aperture in the paper pressing plate, the paper pressing plate can be directly driven to turn when users open the cover plate, and the upper paper pick-up roller on the inner side of the paper pressing plate can press a stack of to-be-shredded paper on the paper support box by means of the contraction of the tension spring on the inner side of the paper pressing plate, so that the paper pressing effect and the paper pick-up efficiency can be effectively improved. 
     Second, according to the paper pressing structure for an automatic shredder, when users open the shredder cover, the paper pressing base plate will be naturally released under gravity; a stack of to-be-shredded paper is placed on the paper support box, then the shredder cover is closed, the big pressing plate (or the plurality of small pressing plates) on the paper pressing base plate presses against the upper surface of the stack of to-be-shredded paper, and the paper pressing base plate is squeezed to return. With the decrease of the stack of to-be-shredded paper, the paper pressing base plate descends, the upper paper pick-up roller gradually presses the upper surface of the stack of to-be-shredded paper, and the paper pressing strip presses against the upper surface of the stack of to-be-shredded paper at the same time, so that the paper pressing effect and the paper pick-up efficiency can also be effectively improved. 
     Third, compared with existing paper pressing structures provided with compression springs occupying a large space and a paper pressing plate having a large overall thickness, the two solutions above effectively simplify the structure, decrease the overall thickness of the paper pressing plate, reduce the moving distance of the paper pressing plate, and have the characteristics of ingenious design, reasonable structure, easy operation, large paper pressing force, high paper pick-up efficiency, and the like, thus being suitable for wide application and popularization on the market. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To more clearly explain the technical solutions of the embodiments of the invention, drawings used for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are merely for illustrating some embodiments of the invention, and those skilled in the art can obtain other drawings according to the following ones without creative labor. In the Drawings: 
         FIG.  1    is a structural view of a cover plate, in an open state, of a paper pressing mechanism for an automatic shredder embodiment of the invention; 
         FIG.  2    is a structural view of the paper pressing mechanism, with the cover plate being hidden, for an automatic shredder embodiment of the invention; 
         FIG.  3    is a structural view of the paper pressing mechanism, with an upper shredder cover and the cover plate being hidden, for an automatic shredder embodiment of the invention; 
         FIG.  4    is a structural view of the paper pressing mechanism, with the upper shredder cover and a paper pressing plate being hidden, for an automatic shredder embodiment of the invention; 
         FIG.  5    is a bottom view of the upper shredder cover of the paper pressing mechanism for an automatic shredder embodiment of the invention; 
         FIG.  6    is a matching diagram of a torsion spring and a spindle of the paper pressing mechanism for an automatic shredder embodiment of the invention; 
         FIG.  7    is a matching diagram of the torsion spring and a spindle holder of the paper pressing mechanism for an automatic shredder embodiment of the invention; 
         FIG.  8    is a structural view of the paper pressing plate of the paper pressing mechanism of an automatic shredder embodiment of the invention; 
         FIG.  9    is a structural view of the cover plate of the paper pressing mechanism for an automatic shredder embodiment of the invention; 
         FIG.  10    is a bottom view of a matching structure of the cover plate and the paper pressing plate of the paper pressing mechanism for an automatic shredder embodiment of the invention; 
         FIG.  11    is a perspective view of the matching structure of the cover plate and the paper pressing plate of the paper pressing mechanism for an automatic shredder embodiment of the invention; 
         FIG.  12    is sectional view of a big pressing plate (or small pressing plates), pressed in place, of a paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  13    is a sectional view of the big pressing plate (or small pressing plates), returning to an original position, of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  14    is a sectional view of the big pressing plate (or small pressing plates), in pressed state at the end of paper shredding, of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  15    is a sectional view of the big pressing plate (or small pressing plates) returning to an original position after paper is placed in the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  16    is a matching diagram of a spindle torsion spring and a base plate spindle of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  17    is a matching diagram of the spindle torsion spring and a base plate spindle holder of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  18    is a structural view of a big pressing plate of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  19    is a top view of a matching structure of the big pressing plate and a paper pressing base plate of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  20    is a bottom view of the matching structure of the big pressing plate and the paper pressing base plate of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  21    is a structural view of small pressing plates of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  22    is a top view of a matching structure the small pressing plates and the paper pressing base plate of the paper pressing structure having a pressing plate spindle of an integrated structure for an automatic shredder embodiment of the invention; 
         FIG.  23    is a top view of a matching structure of the small pressing plates and the paper pressing base plate of the paper pressing structure having the pressing plate spindle divided into a plurality of small pressing plate spindles for an automatic shredder embodiment of the invention; 
         FIG.  24    is a bottom view of the matching structure of the small pressing plates and the paper pressing base plate of the paper pressing structure having the pressing plate spindle divided into a plurality of small pressing plate spindles for an automatic shredder embodiment of the invention; 
         FIG.  25    is a structural view of the paper pressing base plate, to be released, of the paper pressing structure for an automatic shredder embodiment of the invention; 
         FIG.  26    is a structural view of the paper pressing base plate, returning to a limit position, of the paper pressing structure for an automatic shredder embodiment of the invention. 
     
    
    
     Some embodiments are described in detail with reference to the related drawings. Additional embodiments, features and/or advantages will become apparent from the ensuing description or may be learned by practicing the invention. In the figures, which are not drawn to scale, like numerals refer to like features throughout the description. The following description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the invention will be clearly and completely described and discussed below in conjunction with the accompanying drawings of the invention. Obviously, the embodiments in the following description are merely illustrative, and are not all possible ones of the application. All other embodiments obtained by those ordinarily skilled in the art on the basis of the following ones without creative labor should also fall within the protection scope of the application. 
     Representative Embodiment 1 
     As shown in  FIG.  1   - FIG.  11   , the invention discloses an automatic shredder, having a paper pressing mechanism, which is commonly used in a case where user paper (e.g., Letter- or A4-size) cannot be flatly placed on a paper support box (similar to a compact automatic shredder), and includes a cutting mechanism, an upper shredder cover  101 , a lower shredder cover  102 , a paper support box  103 , a paper pressing plate  104 , a cover plate  105 , a spindle  106 , and two spindle holders  108 . The upper shredder cover  101  is vertically and fixedly connected to the lower shredder cover  102 . The paper support box  103  is concavely disposed above the lower shredder cover  102  to form an accommodating cavity for accommodating a stack of to-be-shredded paper. Fixed ends of the paper pressing plate  104  and the cover plate  105  are disposed around the spindle  106 , so that free ends of the paper pressing plate  104  and the cover plate  105  are able to rotate coaxially. In this embodiment, as shown in  FIG.  10   , a joint of the cover plate  105  and the spindle  106  is located on an outer side of a joint of the paper pressing plate  104  and the spindle  106 , so that the paper pressing plate  104  can be covered by the cover plate  105 . 
     Two ends of the spindle are respectively disposed in the two spindle holders, so that the spindle  106  is able to rotate. In this embodiment, the paper pressing mechanism further includes two torsion springs  107  which are separately disposed around the two ends of the spindle  106  and are respectively arranged in the two spindle holders  108  at the two ends of the spindle  106 , as shown in  FIG.  6    and  FIG.  7   . The rotating force of the torsion springs  107  at the two ends of the spindle  106  can be fully used to realize automatic return of the cover plate  105  after the cover plate  105  is opened by a user. 
     The two spindle holders  108  are fixedly connected to the upper shredder cover  101  to fixedly connect the cover plate  105  and the paper pressing plate  104  to the upper shredder cover  101 . In this embodiment, the connection manner of the spindle holders  108  and the upper shredder cover  101  is not limited, and any fixed connection manners such as screwed connection, clamped connection and welded connection can be adopted. The paper pressing plate  104  is disposed below the cover plate  105  and is used for pressing the stack of to-be-shredded paper placed on the paper support box  103  when the user closes the cover plate  105 . 
     Furthermore, the paper pressing mechanism further includes at least one limiting assembly which has a positioning aperture  109 , a positioning column  110 , an elastic component  111  and a stop component  112 . The positioning aperture  109  is formed in the paper pressing plate  104 . The positioning column  110  matches the positioning aperture  109  in position, one end of the positioning column  110  is fixed to an inner side of the cover plate  105 , and the other end of the positioning column  110  penetrates through the positioning aperture  109 . The stop component  112  is connected to the end, away from the cover plate  105 , of the positioning column  110 , and the peripheral size of the stop component  112  is greater than the diameter of the positioning aperture  109 , so that the free end of the paper pressing plate  104  is able to move between the two ends of the positioning column  110 . One end of the elastic component  111  is fixed to a lower surface of the paper pressing plate  104 , and the other end of the elastic component  111  is fixed to the spindle  106 . When the user opens the cover plate  105 , the stop component  112  drives the paper pressing plate  104  to turn upwards along the positioning column  110 , and the elastic component  111  is in stretched state. When the user closes the cover plate  105 , the elastic component  111  contracts to automatically drive the paper pressing plate  104  to turn downwards along the positioning column  110  to enable the paper pressing plate  104  press against an upper surface of the stack of to-be-shredded paper, and the elastic component  111  is in a contracted state. 
     In embodiments, as shown in  FIG.  5   ,  FIG.  10    and  FIG.  11   , the paper pressing mechanism includes two limiting assemblies, which are distributed left and right to ensure uniform stress of the two sides of the paper pressing plate  104  and specifically include two positioning apertures  109 , two positioning columns  110 , two elastic components  111  and two stop components  112 . The two positioning apertures  109  are symmetrically formed in the paper pressing plate  104 . One ends of the two positioning columns  110  are symmetrically arranged on the inner side of the cover plate  105 , and the other ends of the two positioning columns  110  penetrate through the two positioning apertures  109  respectively and match the two positioning apertures  109  in position. In this embodiment, the positioning columns  110  and the cover plate  105  are manufactured integrally to effectively reduce the installation cost, or are detachably connected and fixed through the cooperation of internal and external threads, or are fixedly connected in other manners. 
     The two stop components  112  are respectively connected to the ends, away from the cover plate  105 , of the two positioning columns  110 , and the peripheral sizes of the two stop components  112  correspond to the diameters of the two positioning apertures  109 . As shown in  FIG.  5    and  FIG.  9   ,  FIG.  10   , and  FIG.  11   , the stop components  112  are screws in this embodiment. In embodiments, the stop components  112  may be screws, nuts, bolts, clamping pin, positioning pins, stop pins or other components that can fulfill a limit effect. 
     One ends of the two elastic components  111  are fixed to a lower surface of the paper pressing plate  104 , and the other ends of the two elastic components  111  are connected to the spindle  106  in a hooked manner. In a preferred embodiment, the elastic components  111  are tension springs have one ends fixedly connected to elastic component holders  116  on the lower surface of the paper pressing plate  104  and the other ends connected to the spindle  106  in a hooked manner. In embodiments, when the number of the tension springs is greater than or equal to two, the distance from joints of one ends of the plurality of tension springs and the elastic component holders  116  to the spindle  106  are equal, and the distances from the joints of one ends of the plurality of tension springs and the elastic component holders  116  to the lower surface of the paper pressing plate  104  are also equal, so that tensile forces applied to all positions of the paper pressing plate  104  by the torsion springs are uniform, the stress borne by the stack of to-be-shredded paper on the paper support box  103  is also uniform, and paper dislocation caused by non-uniform stress applied to the stack of to-be-shredded paper is avoided. 
     In embodiments, the positioning apertures  109  may be linear, oval or oblong. As shown in  FIG.  8   , the positioning apertures  109  are oblong optimally, in which the diameter of two semicircular parts is slightly greater than that of the positioning columns  110 , and the distance between two straight side plates is slightly greater than the diameter of the positioning columns  110 , so that the positioning columns  110  can turn and move in the positioning apertures  109  along with the paper pressing plate  104 . In embodiments, long edges of the positioning apertures  109  are perpendicular to the long axis of the spindle  106 , so that the paper pressing plate  104  can turn smoothly and will not get stuck. 
     Furthermore, the paper pressing mechanism further includes at least one paper pick-up roller set which includes an upper paper pick-up roller  113  and a lower paper pick-up roller  114 . The upper paper pick-up roller  113  is fixed between two upper paper pick-up roller seats  115  at a lower end of the paper pressing plate  104  through an upper paper pick-up roller spindle (not shown). The lower paper pick-up roller  114  is fixed to two sides of the lower shredder cover  102  or between two lower paper pick-up roller seats (not shown) at a lower end of the paper support box  103  through a lower paper pick-up roller spindle (not shown). The lower paper pick-up roller  114  partially protrudes out an upper surface of the paper support box  103  and corresponds to the upper paper pick-up roller  113  in position, so that when the user closes the cover plate  105 , the upper paper pick-up roller  113  on the paper pressing plate  104  presses against the stack of to-be-shredded paper on the paper support box  103  and coordinates with the lower paper pick-up roller  114  to enable one or more bottom pieces of paper in the stack of to-be-shredded paper to enter a paper inlet in the paper support box  103 . 
     In one embodiment, as shown in  FIG.  5   ,  FIG.  8   ,  FIG.  10    and  FIG.  11   , the paper pressing mechanism has one paper pick-up roller set, in which the upper pick-up roller  113  is located on a middle section of the inner side of the paper pressing plate  104 , and the lower paper pick-up roller  114  is located on a middle section of one side of the paper inlet in the paper support box  103  and corresponds to the upper pick-up roller  113  in position. Optionally, the upper paper pick-up roller  113  and the lower paper pick-up roller  114  are respectively located in the middle of the paper pressing plate  104  and in the middle of one side of the paper inlet in the paper support box  103  respectively, so that it can be effectively ensured that the stress applied to the stack of to-be-shredded paper on the paper support box  103  on two sides of the paper pick-up roller set is uniform. 
     In another embodiment, the paper pressing mechanism includes two paper pick-up roller sets which are symmetrically distributed on the inner side of the paper pressing plate  104  and on one side of the paper inlet in the paper support box  103  respectively. The design of the two paper pick-up roller sets can effectively improve the paper pick-up force and the paper pick-up efficiency. In embodiments, the upper paper pick-up roller spindle is parallel to the lower surface of the paper pressing plate  104 , the lower paper pick-up roller spindle is parallel to the upper surface of the paper support box  103 , and the force applied to the upper surface of the stack of to-be-shredded paper by the upper paper pick-up roller  113  is equal to the force applied to the lower surface of the stack of to-be-shredded paper by the lower paper pick-up roller  114 , so that paper pick-up smoothness is effectively ensured, and paper tilting is avoided. 
     A Specific Operating Principle of Embodiment 1 
     After the user opens the cover plate  105 , the paper pressing plate  104  is driven by the stop component  112  to turn upwards along the positioning column  110 , and the elastic component  111  (tension spring) on the lower surface of the paper pressing plate  104  is stretched. At this moment, a stack of to-be-shredded paper is placed on the paper support box  103 , the cover plate  105  is released, the elastic component  111  (tension spring) on the lower surface of the paper pressing plate  104  contracts to automatically drive the paper pressing plate  104  to turn downwards along the positioning column  110 , the cover plate  105  turns downward synchronously, the upper paper pick-up roller  113  presses against the upper surface of the stack of to-be-shredded paper and coordinates with the lower paper pick-up roller  114  on the paper support box  103  to pick up paper. 
     Representative Embodiment 2 
     As shown in  FIG.  12   - FIG.  26   , the embodiments include an automatic shredder, having a paper pressing structure, which is commonly used in a case where user paper (e.g., A4- or Letter-sized) cannot be flatly placed on a paper support box (similar to a common automatic shredder) and specifically includes an upper shredder cover  201 , a lower shredder cover  202 , a paper support box  203 , a shredder cover  204 , a paper pressing base plate  205 , a base plate spindle  206 , big pressing plate torsion springs (not shown), a pressing plate spindle  207 , a big pressing plate  208 , two spindle torsion springs  209 , two base plate spindle holders  210  and two pressing plate spindle holders  211 . The upper shredder cover  201  is vertically and fixedly connected to the lower shredder cover  202 . The paper support box  203  is concavely disposed above the lower shredder cover  202  to form an accommodating cavity for accommodating a stack of to-be-shredded paper. The shredder cover  204  is connected to one end of the upper shredder cover  201  through a pivot and is used for closing or opening the shredder. One end of the paper pressing base plate  205  is fixedly connected to the base plate spindle  206 . The two spindle tension springs  209  are separately disposed around two ends of the base plate spindle  206  and are respectively arranged in the two base plate spindle holders  210  located at the two ends of the base plate spindle  206 , so that the base plate spindle  206  is able to rotate to drive the paper pressing base plate  205  to rotate, as shown in  FIG.  16    and  FIG.  17   . The two base plate spindle holders  210  are fixedly connected to an inner side of the shredder cover  204  to fixedly connect the paper pressing base plate  205  to the inner side of the shredder cover  204 . In this embodiment, the connection manner of the base plate spindle holders  210  and the shredder cover  204  is not limited, and any fixed connection manner such as screwed connection, clamped connection and welded connection can be adopted. 
     The two big pressing plate tension springs are separately disposed around two ends of the pressing plate spindle  207  and are respectively arranged in the two pressing plate spindle holders  211  located at the two ends of the pressing plate spindle  207 , so that the pressing plate spindle  207  is able to rotate to drive the big pressing plate  208  to rotate. In this embodiment, the connection manner of the pressing plate spindle holders  211  and the paper pressing base plate  205  is not limited either, and any fixed connection manner such as screwed connection, clamped connection and welded connection can be adopted. 
     The big pressing plate  208  is rotatably connected to the paper pressing base plate  205  from below through the pressing plate spindle  207  and is used for pressing the stack of to-be-shredded paper placed on the paper support box  203  when a user closes the shredder cover  204 . 
     As shown in  FIG.  12    and  FIG.  13   , the paper pressing structure further includes at least one paper pick-up roller set including an upper paper pick-up roller  212  and a lower paper pick-up roller  213 . The upper pick-up roller  212  is fixed between two upper paper pick-up roller spindle holders  215  at the end, away from the base plate spindle  206 , of the paper pressing base plate  205  through an upper paper pick-up roller spindle  214 . The lower paper pick-up roller  213  is fixed to two sides of the lower shredder cover  202  or between two lower paper pick-up roller spindle holders (not shown) at a lower end of the paper support box  203  through a lower paper pick-up roller spindle (not shown). In this embodiment, the lower paper pick-up roller  213  is located on a side, close to a pivot joint of the shedder cover  204  and the upper shredder cover  201 , of a paper inlet. 
     The lower paper pick-up roller  213  partially protrudes out of an upper surface of the paper support box  203  and corresponds to the upper paper pick-up roller  212  in position. When the user closes the shredder cover  204 , the upper pick-up roller  212  on the paper pressing base plate  205  presses against the stack of to-be-shredded paper on the paper support box  203  and coordinates with the lower paper pick-up roller  213  to enable one or more bottom pieces of paper in the stack of to-be-shredded paper to enter the paper inlet in the paper support box  203 . In this embodiment, when one paper pick-up roller set is configured, the paper pick-up roller set is arranged in the middle. When two paper pick-up roller sets are configured, the two paper pick-up roller sets are symmetrically arranged, as shown in  FIG.  19   ,  FIG.  20   , and  FIG.  22   - FIG.  24   . 
     Furthermore, a paper pressing strip  216  is disposed at the end, away from the base plate spindle  206 , of the paper pressing base plate  205 , is integrated with the paper pressing base plate  205 , and is used for pressing a few pieces of to-be-shredded paper on the paper support box  203  to an upper surface of the paper support box  203 , so that the staple removing efficiency and effect can be indirectly improved. In this embodiment, the paper pressing strip  216 , the upper paper pick-up roller spindle holders  215  and the paper pressing base plate  205  are manufactured integrally. In actual operation, the paper pressing strip  216  may be divided into a plurality of paper pressing blocks which are arranged at equal or unequal intervals, and optimally, the paper pressing blocks are arranged at equal intervals. 
     Continuing to refer to  FIG.  18   , the big pressing plate  208  has a big connecting plate  217  and a big paper pressing plate  218 , in which the big paper pressing plate  218  is, when the paper pressing base plate  205  is naturally released, attached to the upper surface of the paper support box  203  to press the stack of to-be-shredded paper to the upper surface of the paper support box  203 , so that the staple removing efficiency and effect can be effectively improved. 
     Furthermore, a first through-aperture  219  is formed in the big paper pressing plate  218  and matches a travel switch, partially upward protruding out of the paper support box  203 , in position, so that when the stack of to-be-shredded paper on the paper support box  203  is about to be completely shredded or has been completely shredded, the travel switch can be received in the first through-aperture  219  and can feed back the paper shredding condition in time. 
     In  FIG.  18   , an angle A between the big connecting plate  217  and the big paper pressing plate  218  is greater than or equal to 90 degrees. In actual operation, the angle is preferably greater than 90 degrees, so that the travel distance of the paper pressing base plate can be effectively reduced, the paper pressing structure is simpler, and space is saved. In embodiments, the big connecting plate  217  and the big paper pressing plate  218  are manufactured integrally, so that the service life of the big pressing plate  208  can be effectively prolonged, and damage caused by repeated paper pressing is avoided. 
     In another embodiment, as shown in  FIG.  21   - FIG.  24   , the big pressing plate  208  is divided into a plurality of small pressing plates  220  each including a small connecting plate  221  and a small paper pressing plate  222 , and each small paper pressing plate  222  is, when the paper pressing base plate  205  is naturally released, attached to the upper surface of the paper support box  203  to press the stack of to-be-shredded paper to the upper surface of the paper support box  203 , so that the staple removing efficiency and effect can be effectively improved. 
     As shown in  FIG.  23    and  FIG.  24   , when the pressing plate spindle  207  is divided into a plurality of small pressing plate spindles  223 , the number of the small pressing plate spindles  223  is equal to that of the small pressing plates  220 , and the small connecting plates  221  of the plurality of small pressing plates  220  are fixedly connected to the plurality of small pressing plate spindles  223  respectively, and are fixedly connected to the paper pressing base plate  205  through small pressing plate torsion springs (not shown) and small pressing plate spindle holders  224  at two ends of the small pressing plate spindles  223 . In this embodiment, the number of the plurality of small pressing plate spindles  223  is not limited. 
     Alternatively, as shown in  FIG.  22   , when the pressing plate spindle  207  is of an integrated structure, the small connecting plates  221  of the plurality of small pressing plates  220  are fixedly connected to the pressing plate spindle  207 , and are fixedly connected to the paper pressing base plate  205  through the big pressing plate torsion springs and the pressing plate spindle holders  211  at the two ends of the pressing plate spindle  207 . By adoption of the pressing plate spindle  207  of the integrated structure, the cost of the multiple small pressing plate spindles  223  and the small pressing plate spindle holders  224  matched with the small pressing plate spindles  223  can be effectively saved, and the consistency of rotation angles of the small pressing plates  220  can be better guaranteed. 
     Further referring to  FIG.  21    and  FIG.  24   , a second through-aperture  225  is formed in the small paper pressing plate  222 , located in the middle, of the plurality of small paper pressing plates  222 , and matches a travel switch, partially upward protruding out of the paper support box  203 , in position, so that when the stack of to-be-shredded paper on the paper support box  203  is about to be completely shredded or has been completely shredded, the travel switch can be received in the second through-aperture  225  and can feed back the paper shredding condition in time. 
     As shown in  FIG.  21   , angles between the small connecting plates  221  and the small paper pressing plates  222  are equal and are greater than or equal to 90 degrees. In actual operation, the angles are generally greater than 90 degrees, so that the travel distance of the paper pressing base plate can be effectively reduced, the paper pressing structure is simpler, and the space is saved. In embodiments, each small connecting plate  221  and the corresponding small paper pressing plate  222  are manufactured integrally, so that the service life of the small pressing plates  220  can be effectively prolonged, and damage caused by repeated paper pressing is avoided. In addition, it can be indirectly ensured that the angles between the small connecting plates  221  and the small paper pressing plates  222  are equal to make the stress applied on the upper surface of the stack of to-be-shredded paper on the paper support box  203  more uniform. 
     In this embodiment, corresponding to the configuration that the paper pick-up roller set is located on the side, close to the pivot joint of the shredder cover  204  and the upper shredder cover  201 , of the paper inlet, the base plate spindle  206  is disposed away from the pivot join of the shredder cover  204  and the upper shredder cover  201 , and the big pressing plate  208  (or the plurality of small pressing plates  220 ) are located on a side, away from the pivot joint, of the shredder cover  204  and the upper shredder cover  201 , of the paper inlet, correspondingly. In this way, it can be effectively ensured that the bottom piece of paper in the stack of to-be-shredded paper on two sides of the paper inlet can be upward fed into the paper inlet from two sides. 
     A Specific Operating Principle of Embodiment 2 
     When the user opens the shredder cover  204 , the paper pressing base plate  205  is naturally released (as shown in  FIG.  25   ) under gravity. A stack of to-be-shredded paper is placed on the paper support box  203 , and then the shredder cover  204  is closed. The big pressing plate  208  (the plurality of small pressing plates  220 ) on the paper pressing base plate  205  presses against the upper surface of the stack of to-be-shredded paper, and the paper pressing base plate  205  is squeezed to return (as shown in  FIG.  15   ). With the decrease of the stack of to-be-shredded paper, the paper pressing base plate  205  descends, the upper paper pick-up roller  212  gradually presses the upper surface of the stack of to-be-shredded paper, and the paper pressing strip  216  presses against the upper surface of the stack of to-be-shredded paper at the same time (as shown in  FIG.  14   ), so that the paper pick-up efficiency can be effectively improved. 
     The foregoing description is merely for explaining preferred specific implementations of the invention, but is not intended to the limit the protection scope of the invention. All transformations or substitutions easily obtained by anyone skilled in the art should fall within the protection scope of the invention. Thus, the protection scope of the invention should be subject to the protection scope defined by the claims.