Patent Publication Number: US-6705224-B2

Title: Stamp apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a stamp apparatus and, in particular, to an apparatus for impressing a paper-sheet object with a mark continuously from a predetermined position to another predetermined position. The present invention is applicable, for example, to a machine for canceling a stamp bonded on a postal matter with a postmark (automatic flat canceling machine). 
     2. Description of the Related Art 
     A conventional stamp apparatus will be described with reference to FIG.  1 . The stamp apparatus comprises a presser roller  31 , an impress hub  32 , a timing disk  33 , a proximity switch  34 , and a pair of photoelectric sensors  35   a  and  35   b.    
     The structure of the stamp apparatus will be described in detail. The presser roller  31 , rotatably supported to one end of an L-shaped arm  36 , is always rotated clockwise by a motor (not shown). The arm  36  is rotatable about a point of support  36   a  thereof. The other end of the arm  36  is pulled by a coil spring  37 . Therefore, the arm  36  rotates counterclockwise, however, more than a predetermined rotational angle in the left direction is limited by a stopper  38 . Adjusting the position of the stopper  38  changes the rotational angle of the arm  36  until a vicinity of the other end of the arm  36  abuts the stopper  38 . As a result, a clearance (slightly smaller than the thickness of a paper-sheet object  30 ) is changed between the presser roller  31  and a part of printing types  32   b  (part having a predetermined character/symbol string) of the impress hub  32 . 
     The impress hub  32  can counterclockwise rotate about the center  32   a , and has the part of printing types  32   b  with a sectorial shape ranging over approximately 180°. The radius of the part of printing types  32   b  is larger than that of the impress hub  32 . The sectorial timing disk  33  fixed to the impress hub  32  has a cut-out  33   a  ranging over approximately 90°. 
     At a predetermined time after an edge of a paper-sheet object  30  being conveyed at a predetermined speed passes through between an emitting sensor  35   a  and a receiving sensor  35   b , the paper-sheet object  30  enters between the presser roller  31  and the impress hub  32 , which are located at an initial position (position shown in FIG.  1 ). Then, since the presser roller  31  is pushed up by the paper-sheet object  30 , the arm  36  rotates clockwise about a supporting point  36   a . An impress-starting position on the paper-sheet object  30  reaches between the presser roller  31  and the impress hub  32 , a motor (not shown) for the impress hub  32  rotates owing to the detection of the paper-sheet object  30  by the pair of sensors  35   a  and  35   b  and to a function of a delay circuit. Therefore, the impress hub  32  is rotated so as to initiate to impress the paper-sheet object  30  with the part of printing types  32   b . When the impress hub  32  is rotated around in a complete circle and the cut-out  33   a  of the timing disk  33  is detected by the proximity switch  34 , the impress hub  32  stops at the initial position. Up to this point, one cycle of impress is completed. 
     As the surface of the presser roller  31  is made of an elastic material such as rubber, the surface is slightly compressed when being urged by the paper-sheet object  30 . 
     In the conventional stamp apparatus, the urging force of the presser roller  31  to the paper-sheet object  30  is adjusted with the coil spring  37 . Therefore, a paper-sheet object  30  having a predetermined thickness or more cannot pass through between the presser roller  31  and the part of printing types  32   b  of the impress hub  32 . 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a stamp apparatus, in which even a thick paper-sheet object can pass through between a presser roller and a part of printing types of an impress hub. 
     According to the present invention, a stamp apparatus is provided, which comprises an impress hub having a predetermined character/symbol string, a presser roller for urging a paper-sheet object to the impress hub, for impressing the predetermined character/symbol string to the paper-sheet object being conveyed between the impress hub and the presser roller, and a presser mechanism, comprising an arm having the presser roller, for suppressing a rebound produced when the presser roller starts to urge the paper-sheet object by rotating the arm so as to urge the presser roller to the paper-sheet object and simultaneously for maintaining a predetermined urging pressure of the presser roller relative to the paper-sheet object having a predetermined thickness at most. 
     The present invention described above has advantages as follows. 
     1. A thick paper-sheet object having a predetermined thickness and below can smoothly pass through between the presser roller and the impress hub. 
     2. A rebound produced when the presser roller starts to urge a paper-sheet object to the impress hub is suppressed so that the paper-sheet object having a predetermined thickness and below can be clearly impressed. 
     3. As the stamp apparatus may further comprise a separating lever, the separating lever separates a paper-sheet object from the impress hub immediately after completion of impressing the paper-sheet object by the impress hub, so that the needless contact between the paper-sheet object and the impress hub can be avoided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a conventional stamp apparatus. 
     FIG. 2 is a front view of a stamp apparatus according to a first embodiment of the present invention. 
     FIG. 3 is a drawing for illustrating the operational timing in the stamp apparatus according to the first embodiment of the present invention. 
     FIG. 4 is a front view of a stamp apparatus according to a second embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Stamp apparatuses according to two embodiments of the present invention will be described. 
     First, a first embodiment will be described with reference to FIGS. 2 and 3. In the stamp apparatus, a paper-sheet object  30  is conveyed in the arrow direction between an impress hub  2  and a presser roller  1  which urges the paper-sheet object  30  to the impress hub  2 . The impress hub  2  has a part of printing types (part having a predetermined character/symbol string) on the peripheral surface over a range of approximately 250°. 
     The presser roller  1 , having a pulley  1   a  integrally formed on the side face thereof, is rotatably supported at one end  3   a  of a substantially L-shaped arm  3 . The arm  3  is rotatable about a shaft  4  as a supporting point, and in a vicinity of the other end of the arm  3 , a roller  5  is provided. In the shaft  4 , a pulley  6  is rotatably supported, and a rope (i.e., round belt)  7  is wound around and stretched between the pulleys  6  and  1   a . A rope  9  is also wound around and stretched between the pulley  6  and a motor  8 . A cam  10  is rotatably supported to a shaft  11  and is directly connected to a rotary solenoid  12 . The cam  10  is pressed into contact with the roller  5 . The rotary solenoid  12  outputs a predetermined torque when rotating by a given angle. The profile of the external periphery  10   a  of the cam  10  is formed such that a rate of increase in the angle of rotation of the arm  3  having the presser roller  1  is reduced with increasing angle of rotation of the rotary solenoid  12 . By such a configuration, even when the thickness of a paper-sheet object  30  is small, the paper-sheet object  30  can be urged to the impress hub  2  under a proper pushing pressure. Since the arm  3  is being pulled by a coil spring  13 , the rotation of the cam  10  in the direction opposite to the arrow is limited by the abutment of one end of the cam  10  to a stopper  14 . An initial position of the presser roller  1  (position of the presser roller  1  being most separated from the impress hub  2 ) is determined by the tensile force of the coil spring  13  and the position of the stopper  14 . When the cam  10  excessively rotates in the arrow direction, one end of the cam  10  abuts a shock absorber  15 . 
     In order not to change a conveying speed of a paper-sheet object  30  when the presser roller  1  is urging the paper-sheet object  30  to the impress hub  2 , the presser roller  1  is constructed so as to rotate at the same peripheral speed as the conveying speed of the paper-sheet object  30 . 
     The segment surrounded by the closing line in FIG. 2 is referred to as a presser mechanism  16 . 
     The impress hub  2  is rotated by a servomotor  17  via a rope  18 . A separating lever  19  can be rotated about a shaft  20  by a rotary solenoid  21  in the arrow direction from an initial position (position shown by FIG. 2) to a siding position (position not in touch with a paper-sheet object  30 ). The rotary solenoid  21  is excited at the initial position. 
     A pair of emitting and receiving sensors  22   a  and  22   b  detect leading and trailing edges of a paper-sheet object  30  while a control unit  23  performs controls, which will be described later. 
     When the leading edge of a paper-sheet  30  being conveyed at a predetermined speed in the arrow direction is detected by the pair of photoelectric sensors  22   a  and  22   b , the control unit  23  cancels the excitation of the rotary solenoid  21  while exciting the rotary solenoid  12 . Accordingly, the separating lever  19  rotates from the initial position to the siding position. As the cam  10  also rotates in the arrow direction, it makes the presser roller  1  approach the impress hub  2  via the roller  5  and the arm  3 . When the paper-sheet object  30  is conveyed between the impress hub  2  and the presser roller  1 , a stamp bonded on the bottom surface of the paper-sheet object  30  is canceled with a postmark. At a predetermined time after the pair of photoelectric sensors  22   a  and  22   b  detect the trailing edge of the paper-sheet object  30 , the control unit  23  excites the rotary solenoid  21  while canceling the excitation of the rotary solenoid  12 . Accordingly, the separating lever  19  rotates from the siding position to the initial position. At this time, the separating lever  19  separates the paper-sheet object  30  from the impress hub  2 . Also, the presser roller  1  is moved from the position close to the impress hub  2  to the initial position by the coil spring  13 . 
     The operational timing of the stamp apparatus according to the first embodiment will be described with reference to FIG.  3 . 
     The pair of photoelectric sensors  22   a  and  22   b  detect the leading edge of a paper-sheet object  30  (thick object with a thickness of one inch and below, for example) being conveyed at a predetermined speed (1.5 m/s, for example) so as to output a leading-edge signal. The control unit  23  excites the rotary solenoid  12  at a predetermined time T 1  (58 ms, for example) after receiving the leading-edge signal. Then, the rotary solenoid  12  is excited so that the cam  10  and the arm  3  are rotated so as to move the presser roller  1  from the initial position to the position close to the impress hub  2 . At a predetermined time (68 ms, for example) after the control unit  23  receives the leading-edge signal, the impress hub  2  starts to rotate so that the paper-sheet object  30  is conveyed to between the presser roller  1  and the impress hub  2 . 
     At a predetermined time T 2  (98 ms, for example) after receiving the leading-edge signal, which is the timing when the impress-starting position of the paper-sheet object  30  arrives at between the presser roller  1  and the impress hub  2  and also when the presser roller  1  urges the paper-sheet object  30  to the impress hub  2  by abutting the paper-sheet object  30 , the excitation of the rotary solenoid  21  is canceled. Then, the separating lever  19  is moved from the initial position to the siding position not in touch with the paper-sheet object  30 , so that the impress hub  2  starts to impress the paper-sheet object  30  with a mark. 
     When the rotary solenoid  21  of the separating lever  19  is excited at a predetermined time (218 ms, for example) after the control unit  23  receives the leading edge signal, the separating lever  19  is moved from the siding position toward the initial position so as to start to separate the paper-sheet object  30  from the impress hub  2 . The pair of photoelectric sensors  22   a  and  22   b  detect the trailing edge of the paper-sheet object  30  so as to output a trailing edge signal. The control unit  23  stops the rotation of the impress hub  2  at a predetermined time T 3  (38 ms, for example) after receiving the trailing edge signal. As for the rotational position of the impress hub  2 , the position starting the impressing is configured to be the same as the stopping position when completing the impressing. When canceling the excitation of the rotary solenoid  12 , the arm  3  is clockwise rotated about the shaft  4  until one end of the cam  10  abuts the stopper  14  by the tensile force of the coil spring  13 . As a result, while the presser roller  1  moves to the initial position, the separating lever  19  separates the paper-sheet object  30  from the impress hub  2  during movement to the initial position. 
     Next, a second embodiment will be described with reference to FIG.  4 . The description of the same parts of the second embodiment as those of the first embodiment is omitted and only different points will be described. 
     A pulley  24  fixed to the arm  3  is rotatably supported in the shaft  4 . The pulley  24  is rotated by a required angle by a servomotor  26  via a rope  25 . 
     The segment surrounded by the closing line in FIG. 4 is referred to as a presser mechanism  27 . 
     By a thickness sensor  28  arranged upstream the pair of photoelectric sensors  22   a  and  22   b , the thickness S of a paper-sheet object  30  is detected in advance. A control unit  29  controls the rotation of the servomotor  26  in accordance with the thickness S of the paper-sheet object  30 . The presser roller  1  is movable between a predetermined initial position not in touch with the paper-sheet object  30  and a position spaced by a length S from the impress hub  2 . A rebound produced when the presser roller  1  starts to urge the paper-sheet object  30  to the impress hub  2  is suppressed by a torque controlling function of the servomotor  26 .