Abstract:
A thickness detection device comprises: a feed roller ( 130 ), a thickness detection unit ( 110,210 ) and a thickness measurement unit ( 120,220 ). The thickness detection unit ( 110, 210 ) comprises a detection roller ( 113, 213 ) which is contacted with the surface of the feed roller ( 130 ), a detection rotating shaft ( 111, 211 ) and a reflective board for thickness detection ( 112, 212 ); the thickness detection reflective board ( 112, 212 ) comprises an enlarging part ( 112   a,    212   a ) and a bending part ( 112   b,    212   b ) connected to one end of the enlarging part ( 112   a,    212   a ); the detection roller ( 113, 213 ) and the detection rotating shaft ( 111, 211 ) are both arranged on the bending part ( 112   b,    212   b ), a connection line of the axle centers of the detection roller ( 113, 213 ) and the detection rotating shaft ( 111, 211 ) is at an included angle with the enlarging part ( 112   a,    212   a ) of the reflective board for thickness detection ( 112, 212 ); and the thickness measurement unit ( 120, 220 ) comprises a sensor used for measuring the distance that the enlarging part ( 112   a,    212   a ) rotates around the detection rotating shaft ( 111, 211 ).

Description:
[0001]    This application claims priority to Chinese Patent Application No. 200910039865.8, filed on May 31, 2009 with the Chinese Patent Office, entitled “Thickness Detection Device”, which is incorporated herein by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a thickness detection system, in particular, to a thickness detection device for sheet-type media. 
       BACKGROUND OF THE INVENTION 
       [0003]    A typical thickness detection device for sheet-type media generally includes a sensor and a thickness detection unit including a detecting portion and an amplifying portion. When a sheet-type medium passes through the thickness detection device, the sensor measures the movement distance of the amplifying portion of the thickness detecting unit, and then a thickness value of the medium is obtained by calculation. However, a typical thickness detection unit is complex in configuration and easy to result in measuring errors. In addition, it is difficult to determine an initial position of the sensor relative to the thickness detection unit. The accuracy of a final measuring result will be decreased due to the change of the initial position of the sensor. Some thickness detection devices in which the initial position of the sensor is adjustable have been proposed, but an adjustment mechanism therein is complicated in configuration, troublesome in the adjustment process and inconvenient in maintenance. 
         [0004]    Thus, a need exists for an improved thickness detection device to overcome the defects mentioned above. 
       SUMMARY OF THE INVENTION 
       [0005]    In view of the shortcomings in the prior art mentioned above, an object of the present invention is to provide a thickness detection device with simple configuration and high measuring accuracy, which is easy to be operated, stable and reliable. 
         [0006]    In order to achieve the above object, according to the invention there is provided a thickness detection device, comprising: a feed roller; a thickness measuring unit; and a thickness detection unit including a detection roller in surface contact with the feed roller, a detection shaft, and a thickness detecting reflection plate. The thickness detecting reflection plate comprises an amplifying portion and a bended portion connected to one end of the amplifying portion. The detection roller and the detection shaft are disposed at the bended portion. An included angle is formed between a line connecting an axle center of the detection roller with that of the detection shaft and the amplifying portion of the thickness detecting reflection plate. The thickness measuring unit comprises a sensor for measuring a rotation distance of the amplifying portion around the detection shaft. With the detection shaft functioning as a fulcrum, a lever mechanism is formed by the detection shaft, the detection roller and the thickness detecting reflection plate. A slight distance change occurred during the passage of a sheet-type medium is amplified by means of the lever principle, and then the amplified distance is measured and the thickness of the medium is calculated, which enables the device to be simple in configuration and easy to be implemented. 
         [0007]    In an embodiment of the thickness detection device according to the invention, the thickness detection unit further comprises a base including a bottom plate and an extension which is provided at a side of the bottom plate and which has two mounting arms, a pair of positioning holes are correspondingly provided through the mounting arms, the detection shaft passes through the positioning holes and the bended portion of the thickness detecting reflection plate, and the bended portion is located between the two mounting arms. 
         [0008]    The thickness measuring unit further comprises a sensor distance adjustment mechanism for adjusting a position of the sensor with regard to the thickness detecting reflection plate, the sensor distance adjustment mechanism comprising a sensor securing plate connected to the base in a manner that the sensor securing plate can move up and down. Measuring results can be more accurate by adjusting an initial position of the sensor relative to the amplifying portion. 
         [0009]    In detail, the sensor distance adjustment mechanism further comprises an adjusting screw including a first and a second threaded portions, a thread pitch of the first threaded portion is larger than that of the second threaded portion, the sensor securing plate and the base are, respectively, formed with female threaded studs in correspondence with the first and the second threaded portions. The sensor securing plate is connected to the base through mating the adjusting screw with the female threaded studs at the sensor securing plate and the base. The initial position of the sensor is adjusted by using the adjusting screw having two sections with different thread pitches, which enables the device to be simple in configuration and easy to be assembled and operated. 
         [0010]    Preferably, the sensor distance adjustment mechanism further comprises a sensor adjusting compression spring fitted over the adjusting screw and the female threaded studs at the sensor securing plate and the base, in order for eliminating a matching clearance between the screw and the threaded holes. 
         [0011]    Preferably, the sensor securing plate comprises a top cover and two second side walls which are located on both opposite sides of the top cover and through which threaded holes are correspondingly provided, the base further comprises two first side walls which are located on both opposite sides of the base and through which two through slots are provided at positions in correspondence with the threaded holes, and the sensor distance adjustment mechanism further comprises a fastener passing through the threaded hole and the through slot so as to fix the top cove in relation to the base. 
         [0012]    In another embodiment of the invention, the thickness detection device further comprises a vibration damping mechanism comprising a sensor damping compression spring fitted over the detection shaft and located between the thickness detecting reflection plate and one of the mounting arms of the extension. When the thickness detecting plate vibrates up and down, a pressure applied to the thickness detecting reflection plate by the sensor damping compression spring will decrease its redundant vibrations, which makes the whole device more stable and measuring results more accurate. 
         [0013]    Optionally, the vibration damping mechanism further comprises a reflection baffle compression spring located between the thickness detecting reflection plate and the bottom plate of the base, maintaining the thickness detecting reflection plate in the upward initial state at all time, thereby eliminating signal noises caused by configurations and resulting in more accurate measuring results. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    For clearer description of technical solutions in embodiments of the present invention or in the prior art, the Drawings necessary for such description will be now explained in brief. Obviously, the Drawings described below are only illustrative of some of the embodiments of the present invention. Further drawings can be achieved by the skilled in the art in accordance with the Drawings described herein without making any inventive efforts. 
           [0015]      FIG. 1  is a structural schematic view of an embodiment of the thickness detection device according to the present invention. 
           [0016]      FIG. 2  is a perspective view of another embodiment of the thickness detection device according to the present invention. 
           [0017]      FIG. 3  is a perspective view of a sensor distance adjustment mechanism of the thickness detection device of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The technical solutions in embodiments of the present invention will be described clearly and completely with reference to the Drawings thereof. Obviously, the embodiments described are only a part of embodiments of the invention, but not all of them. Based on the embodiments in the invention, all further embodiments which are achieved by the skilled in the art without making inventive efforts will fall within the protective scope of the invention. 
         [0019]    With reference to  FIG. 1 , an embodiment of the thickness detection device  100  according to the invention includes: a feed roller  130 ; a thickness detection unit  110  composed of a detection shaft  111 , a detection roller  113  in surface contact with the feed roller  130 , and a thickness detecting reflection plate  112  composed of an amplifying portion  112   a  and a bended portion  112   b  connected to a side of the amplifying portion  112   a,  wherein the detection roller  113  and the detection shaft  111  are mounted at the bended portion  112   b , there is an included angle a between a line  117  connecting an axle center of the detection roller  113  with that of the detection shaft  111  and the amplifying portion  112   a  of the thickness detecting reflection plate  112 , and the thickness detection unit  110  is fixed by the detection shaft  111 ; and a thickness measuring unit  120  positioned above the amplifying portion  112   a  of the thickness detecting reflection plate  112  to measure a rotation distance of the amplifying portion  112   a  about the detection shaft  111 . Specifically, the thickness measuring unit  120  may be a sensor. 
         [0020]    With the detection shaft  111  functioning as a fulcrum, a lever mechanism is formed by the detection shaft  111 , the detection roller  113  and the thickness detecting reflection plate  112 . When a sheet-type medium  115  passes between the feed roller  130  and the detection roller  113 , the thickness detecting reflection plate  112  will be caused to rotate about the detection shaft  111  by the movement of the detection roller  113 . The thickness of the sheet-type medium  115  is amplified by the lever mechanism, producing an amplified value corresponding to the real thickness. That is, the rotation distance of the thickness detecting reflection plate  112  is a thickness value of the sheet-type medium after amplification, with an amplification factor being dependent on the length of the amplifying portion  112   a  of the thickness detecting reflection plate  112 . The rotation distance of the thickness detecting reflection plate  112  is measured by the thickness measuring unit  120 , and the thickness value of the sheet-type medium  115  can then be achieved by calculation. The whole thickness detection device  100  is simple in configuration, easy to be implemented and with an accurate measuring result. 
         [0021]    In this embodiment, the detection roller  113  and the detection shaft  111  are positioned on two opposite sides of the amplifying portion  112   a  of the thickness detecting reflection plate  112 , respectively, which leads to a convenient installation and results in a more compact configuration of the thickness detection device. 
         [0022]      FIG. 2  is a structural schematic view of another embodiment of the thickness detection device according to the invention. The thickness detection device  200  of the present embodiment includes: a feed roller (not shown); a thickness detection unit  210  including a detection shaft  211 , a detection roller  213  in surface contact with the feed roller, and a thickness detecting reflection plate  212  including an amplifying portion  212   a  and a bended portion  212   b  connected to a side of the amplifying portion  212   a,  wherein the detection roller  213  and the detection shaft  211  are mounted at the bended portion  212   b,  and an included angle is formed between a line connecting an axle center of the detection roller  213  with that of the detection shaft  211  and the amplifying portion  212   a  of the thickness detecting reflection plate  212 ; a thickness measuring unit  220  including a sensor (not shown) and a sensor distance adjustment mechanism  222  carrying the sensor, wherein the sensor distance adjustment mechanism  222  includes a sensor securing plate  2221 ; and a base  2222  to which the sensor securing plate  2221  connected in a manner of being capable of moving up and down and to which the thickness detection unit  210  is connected via the detection shaft  211 . 
         [0023]    Specifically, as shown in  FIGS. 2 and 3 , the base  2222  includes a bottom plate  2222   a  provided with an extension  2224  and first side walls  2222   b  positioned at two opposite sides of the bottom plate  2222   a,  wherein the extension  2224  is located to a side of the bottom plate  2222   a  without the first side walls  222   b  and includes a connecting plate  2224   b  provided with two mounting arms  2224   a  on both sides thereof, with one of the mounting arms  2224   a  extending from one first side wall  2222   b  and located in the same plane therewith and the other mounting arm  2224   a  substantially perpendicular to the bottom plate  2222   a  and located between the two first side walls  2222   b.  The mounting arms  2224   a  are correspondingly provided with a pair of positioning holes  2224   c  through which the detection shaft  211  passes, thereby the thickness detection unit  210  is mounted within the sensor distance adjustment mechanism  222 . The sensor securing plate  2221  includes: a top cover  2221   a  provided with several through slots and several through holes for installation of the sensor; and two second side walls  2221   b  formed on two opposite sides of the top cover  2221   a.    
         [0024]    The sensor distance adjustment mechanism  222  further includes a sensor adjusting compression spring  2226  and an adjusting bolt  2223  provided with a first threaded portion  2223   a  on a upper threaded rod thereof and a second threaded portion  2223   b  on a lower threaded rod thereof, with a thread pitch of the first threaded portion  2223   a  being larger than that of the second threaded portion  2223   b.  The top cover  2221   a  of the sensor securing plate  2221  and the bottom plate  2222   a  of the base  2222  are correspondingly provided with a first and a second female threaded stud  2221   d  and  2222   d  which extend toward each other from the top cover  2221   a  and the bottom plate  2222   a  and through which are formed a first and a second threaded hole, respectively. The thread pitches of the first and the second threaded holes correspond to those of the first and the second threaded portions  2223   a  and  2223   b  of the adjusting bolt  2223 , respectively. The upper and the lower threaded rods of the adjusting bolt  2223  are respectively mated with the treaded hole with larger thread pitch of the sensor securing plate  2221  and that with smaller thread pitch of the base  2222 , such that the sensor securing plate  2221  is connected to the base  2222  in a manner of being capable of moving up and down. When the adjusting bolt  2223  interacts with the threaded holes on the sensor securing plate  2221  and on the base  2222  simultaneously, rising (descending) linear distances for two sections of threads with different thread pitches caused by one turn of rotation of the adjusting bolt  2223  are different. Here, the sensor securing plate  2221  will correspondingly descend (rise) a certain compensating distance, thereby achieving the purpose of adjusting the position of the sensor. The sensor adjusting compression spring  2226  is disposed to encircle the first and the second female threaded studs  2221   d  and  2222   d , the function of which is to eliminate a matching clearance between the adjusting bolt  2223  and the threaded holes. 
         [0025]    Alternatively, the sensor may be disposed on the top cover  2221   a  of the sensor securing plate  2221  or may be mounted at an inside of a second side wall  2221   b.    
         [0026]    Preferably, the sensor distance adjustment mechanism further includes a fastener (not shown), such as a screw and so on. As shown in  FIG. 3 , threaded holes  2225   a  are correspondingly provided through the two second side walls  2221   b  of the sensor securing plate  2221 , and through slots  2225   b  are provided through the two first side walls  2222   b  of the base  2222  at positions in correspondence with the threaded holes  2225   a.  The screw passes through the threaded hole  2225   a  and the through slot  2225   b.  When the adjustment of the relative position between the sensor securing plate  2221  and the base  2222  is done, i.e., after the sensor is adjusted to a correct position, the sensor securing plate  2221  is fixed with regard to the base  2222  through mating the screw with the threaded hole  2225   a  and with the through slot  2225   b  by tightening the screw, such that the initial position of the sensor is thereby accurately adjusted. 
         [0027]    In addition, with reference to  FIG. 2 , the thickness detection device  200  further includes a vibration damping mechanism  230 . The vibration damping mechanism  230  includes: a sensor damping compression spring  231  which is disposed to encircle (to be fitted over) the detection shaft  211  and located between the bended portion  212   b  of the thickness detecting reflection plate  212  and a mounting arm  2224   a  of the extension  2224 ; and a reflection baffle compression spring  232  fixedly disposed between the amplifying portion  212   a  of the thickness detecting reflection plate  212  and the bottom plate  2222   a  of the base  2222 . The sensor damping compression spring  231  can damp vibrations occurred by the thickness reflection plate  212  during operation to some extent. Moreover, the reflection baffle compression spring  232  fixedly disposed between the amplifying portion  212   a  of the thickness detecting reflection plate  212  and the bottom plate  2222   a  of the base  2222  maintains the thickness detecting reflection plate  212  in the upward initial state at all time, thereby mechanically eliminating unwanted vibrations and leading to a more stable measuring system and more accurate measuring results. 
         [0028]    Although the sensor adjusting structure of the present embodiment adjusts the distance between the sensor securing plate and the base by means of female threaded studs in conjunction with an adjusting screw having two sections with different thread pitches, the thickness detection device according to the invention is not limited to this way. In contrast, any structures which enable the relative distance between the sensor securing plate and the base to be changed will fall within the protective scope of the invention. For example, several snapping structures or several traverse slots perpendicular to the through slots may provided at the first side walls, and then the position of the sensor securing plate and thus the initial position of the sensor can be adjusted by means of a fastener in conjunction with these structures. 
         [0029]    Since the sensor distance adjustment mechanism applied in the thickness detection device according to the invention is simple in configuration, easy to be operated and implemented, it becomes simple and easy to adjust the initial position of the sensor. In addition, the application of the vibration damping system to the device effectively controls vibrations occurred during the operation of the thickness detecting reflection plate, thereby enabling the whole system to be more stable and the measuring result to be more accurate. 
         [0030]    It is to be noted that the sensor distance adjustment mechanism and the vibration damping mechanism described above are independent structures from each other, and the thickness detection device of the present invention may include only one of them. 
         [0031]    What is disclosed above is only preferable embodiments of the invention, it of course cannot be considered to limit the protective scope of the invention. Equivalent modifications and changes made according to the attached claims of the invention will still fall within the protective scope thereof.