Patent Publication Number: US-8979240-B2

Title: Head alignment assembly

Description:
FIELD OF THE INVENTION 
     The present invention relates to a head alignment assembly, and more specifically to a head alignment assembly in which a deviation of the head can be aligned conveniently with simple operation from the outside of the printer head section. 
     BACKGROUND OF THE INVENTION 
     A printer in which a plurality of heads are disposed by aligning them on a base plate to form one head section needs fine adjustment from time to time. 
     A conventional method for fine adjustment of each head is to use a fine adjustment screw for moving the head to move each head in a biaxial direction on a horizontal plane. 
     However such a method is cumbersome since fine adjustment is made to the head by disassembling the head section of a shape closed overall by a casing so the head section should be reassembled again. Further, even though the head section is set to the reference position by one fine adjustment, the fine adjustment work should be performed repeatedly by external factors such as repeatedly applied vibration or external shock. 
     Therefore, the conventional head alignment method has a drawback that not only a long time is taken for fine adjustment work but also alignment work can be performed only by a skilled person who is able to disassemble and assemble the head section. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed to a head alignment assembly comprising: a base plate to which at least one head unit is fixed to be exposed downward by a first head support block and a second head support block; a first fine adjustment section configured to shift the first head support block in a longitudinal direction of the head unit; and a second fine adjustment section configured to shift the second head support block in a transverse direction orthogonal to the longitudinal direction of the head unit; wherein the first fine adjustment section includes a first push rod supported by fixed guides which are fixed on the base plate to press the first head support block; and a first handle fixed to one end of the first push rod to move the first push rod in the longitudinal direction; the second fine adjustment section includes a second push block configured to press the second head support block in the transverse direction; a second push rod supported by a plurality of fixed guides which are fixed on the base plate; and a second handle fixed to one end of the second push rod to move the second push rod in the longitudinal direction. 
     In some embodiments, the first head support block includes a first notch formed integrally thereon, and the first push rod includes an integral push ring of which one end is formed integrally with the other end of the first push rod and the other end contacts the first notch; and a fixed pin of which a lower end is fixed on the base plate and an upper portion is inserted into the integral push ring to limit a displacement of the first push rod in the longitudinal direction. 
     In some embodiments, the first head support block includes a first notch formed integrally thereon, and the first push rod includes a first push block of which one end is formed integrally with the other end of the first push rod and the other end has a second notch formed thereon, wherein a separate push ring is disposed between the first notch and the second notch, and a fixed pin formed on the base plate is inserted into the separate push ring to limit the displacement of the first push rod in the longitudinal direction. 
     In some embodiments, the second head support block includes a driven beam of which one end is formed integrally thereon and the other end protrudes toward the second push block so as to come into contact therewith. 
     In some embodiments, the second head support block includes a driven beam having a long slit formed therein; and a driven beam pin of which a lower end is fixed on the base plate and an upper portion is inserted into the slit, wherein one end of the driven beam pin comes into contact with the second head support block and the other end of the driven beam comes into contact with a sloping side of the second push block. 
     In some embodiments, the base plate includes a first reaction force member which applies a reaction force to the second head support block in a direction opposite to a press direction of the first push block; and a second reaction force member which applies a reaction force to the second head support block in a direction opposite to a press direction of the second push block moved by the second push rod. 
     In some embodiments, the base plate includes a slope reaction force member which applies a reaction force to the second head support block in a diagonal direction between the direction opposite to the press direction of the first push block and the direction opposite to the press direction of the second push block moved by the second push rod. 
     In some embodiments, the first fine adjustment section includes a first support section configured to press the first push rod in a direction toward the first handle, and the second fine adjustment section includes a second support section configured to press the second push rod in a direction toward the second handle. 
     In some embodiments, the base plate includes a guide slot formed thereon so as to contact and support the second push block in a direction orthogonal to the longitudinal direction of the second push rod. 
     In some embodiments, the base plate includes an eccentric bearing which contacts a surface opposite to the sloping side of the second push block in contact with the driven beam of the second head support block; and an eccentric bolt on which the eccentric bearing is rotatably mounted. 
     In some embodiments, the driven beam includes a driven bearing installed at an end portion of the driven beam so as to provide a smooth contact with the second push block. 
     In some embodiments, when two or more heads are arranged on the base plate in serial, the first push rod and the second push rod are installed parallel to each other with different heights. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of a head alignment assembly according to a first embodiment of the present invention. 
         FIG. 2  is a plane view of  FIG. 1 . 
         FIG. 3  is a perspective view of a head alignment assembly according to a second embodiment of the present invention. 
         FIG. 4  is a plane view of  FIG. 3 . 
         FIG. 5  is a plane view of a head alignment assembly according to a third embodiment of the present invention. 
         FIG. 6  is a perspective view of a head alignment assembly according to a fourth embodiment of the present invention. 
         FIG. 7  is a bottom view of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Accordingly, to solve the above-mentioned problems, it is an object of the present invention to provide a head alignment assembly in which a deviation of the head can be aligned conveniently by a simple operation from the outside of the printer head section. 
     Technical Solution 
     In order to accomplish the foregoing objects, according to the present invention, there is provided a head alignment assembly including: a base plate to which at least one head unit is fixed to be exposed downward by a first head support block and a second head support block; a first fine adjustment section configured to shift the first head support block in a longitudinal direction of the head unit; and a second fine adjustment section configured to shift the second head support block in a transverse direction orthogonal to the longitudinal direction of the head unit; wherein the first fine adjustment section includes a first push rod supported by fixed guides which are fixed on the base plate to press the first head support block; and a first handle fixed to one end of the first push rod to move the first push rod in the longitudinal direction; the second fine adjustment section includes a second push block configured to press the second head support block in the transverse direction; a second push rod supported by a plurality of fixed guides which are fixed on the base plate; and a second handle fixed to one end of the second push rod to move the second push rod in the longitudinal direction. 
     Preferably, the first head support block includes a first notch formed integrally thereon, and the first push rod includes an integral push ring of which one end is formed integrally with the other end of the first push rod and the other end contacts the first notch; and a fixed pin of which a lower end is fixed on the base plate and an upper portion is inserted into the integral push ring to limit a displacement of the first push rod in the longitudinal direction. 
     Preferably, the first head support block includes a first notch formed integrally thereon, and the first push rod includes a first push block of which one end is formed integrally with the other end of the first push rod and the other end has a second notch formed thereon, wherein a separate push ring is disposed between the first notch and the second notch, and a fixed pin formed on the base plate is inserted into the separate push ring to limit the displacement of the first push rod in the longitudinal direction. 
     Preferably, the second head support block includes a driven beam of which one end is formed integrally thereon and the other end protrudes toward the second push block so as to come into contact therewith. 
     Preferably, the second head support block includes a driven beam having a long slit formed therein; and a driven beam pin of which a lower end is fixed on the base plate and an upper portion is inserted into the slit, wherein one end of the driven beam pin comes into contact with the second head support block and the other end of the driven beam comes into contact with a sloping side of the second push block. 
     Preferably, the base plate includes a first reaction force member which applies a reaction force to the second head support block in a direction opposite to a press direction of the first push block; and a second reaction force member which applies a reaction force to the second head support block in a direction opposite to a press direction of the second push block moved by the second push rod. 
     Preferably, the base plate includes a slope reaction force member which applies a reaction force to the second head support block in a diagonal direction between the direction opposite to the press direction of the first push block and the direction opposite to the press direction of the second push block moved by the second push rod. 
     Preferably, the first fine adjustment section includes a first support section configured to press the first push rod in a direction toward the first handle, and the second fine adjustment section includes a second support section configured to press the second push rod in a direction toward the second handle. 
     Preferably, the base plate includes a guide slot formed thereon so as to contact and support the second push block in a direction orthogonal to the longitudinal direction of the second push rod. 
     Preferably, the base plate includes an eccentric bearing which contacts a surface opposite to the sloping side of the second push block in contact with the driven beam of the second head support block; and an eccentric bolt on which the eccentric bearing is rotatably mounted. 
     Preferably, the driven beam includes a driven bearing installed at an end portion of the driven beam so as to provide a smooth contact with the second push block. 
     Preferably, when two or more heads are arranged on the base plate in serial, the first push rod and the second push rod are installed parallel to each other with different heights. 
     Advantageous Effects 
     According to the present invention, the fine adjustment of the head can be carried out just with a simple operation of a handle even by an unskilled person. As a result, it is possible to save both the time and cost taken for fine adjustment work. Further, it is more economical because it is also possible to minimize the delay of print out work due to the head fine adjustment. 
     In addition, it is possible to improve the printing quality as the head of the head section can be set accurately to the reference position. 
     Hereinafter, preferable embodiments of the present invention will be described with reference to the accompanying drawings. Referring to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views. In the embodiments of the present invention, detailed description of the publicly known functions and configurations that are judged to be able to make the purport of the present invention unnecessarily obscure are omitted. 
     The biggest characteristic of the head alignment assembly according to first to fourth embodiments of the present invention is in that the alignment of the head unit can be simply adjusted from the outside of the head section without disassembly-assembly work of the head section. 
     For such a characteristic, a head alignment assembly  100  according to the first embodiment includes a first handle  124  and a second handle  104  exposed outside of the head section, as illustrated in  FIGS. 1 and 2 . By using the first handle  124  and the second handle  104 , it is possible to fine adjust a head unit  10  arranged inside of the head section. 
     Such a head alignment assembly  100  includes a base plate  102  to which the head unit  10  is fixed to be exposed downward by a first head support block  132  and a second head support block  134 , a first fine adjustment section for allowing a displacement of the first head support block  132  in a longitudinal direction of the head unit  10 , and a second fine adjustment section for allowing the displacement of the second head support block  134  in a transverse direction orthogonal to the longitudinal direction of the head unit  10 . 
     A plurality of head units  10  may be mounted on the base plate  102 , and slits of a number equal to the head units  10  for the head units  10  to be exposed downward of the base plate  102  are formed on the base plate  102 . Accordingly, when the plurality of head units  10  are disposed in parallel on the base plate  102 , head alignment assemblies  100  of a number equal to the number of the head units  10  are disposed in parallel. 
     The first head support block  132  and the second head support block  134  are installed in the slit, and the head unit  10  is fixed integrally to the first head support block  132  and the second head support block  134 . Therefore, the displacement of the head unit  10  is made by the shifting of the first head support block  132  and the second head support block  134 . 
     The first fine adjustment section includes a first notch  133  formed on the first head support block  132  for allowing the displacement of the head unit  10  in the longitudinal direction thereof, a first push rod  126  supported by fixed guides  108 ,  110  and  112  fixed on the base plate  102 , the first handle  124  fixed to one end of the first push rod  126  so as to move the first push rod  126  in the longitudinal direction, an integral push ring  128  of which one end is formed integrally with the other end of the first push rod  126  and the other end contacts the first notch  133 , and a fixed pin  130  inserted into the integral push ring  128  to be fixed on the base plate  102 . 
     A lower end of the fixed pin  130  is fixed on the base plate  102  to protrude upward and an upper portion thereof is inserted into the integral push ring  128  fixed to the other end portion of the first push rod  126 . Accordingly, the moving length of the first push rod  126  in the longitudinal direction thereof is limited by the fixed pin  130  within the length of the slot of the integral push ring  128  formed integrally therein. 
     The width of the slot formed inside of the integral push ring  128  is formed wider than the diameter of the fixed pin  130  to provide a slight interval for the integral push ring  128 . 
     This interval defines an offset section between the first head support block  132  and the first push rod  126  when the first push rod  126  moves in the longitudinal direction thereof, so that it can provide a clearance to enable the head unit  10  to change position during the fine adjustment by the second fine adjustment section. Further, it is preferable that the internal slit of the integral push ring  128  be formed lengthwise in the longitudinal direction, and the fixed pin  130  have a cross section shape (for example, a rectangular shape) in contact with both sidewalls of the internal slit, so that the integral push ring  128  can move only vertically to the fixed pin  130 . 
     Further, the first head support block  132  includes the first notch  133  that contacts the outer periphery of the integral push ring  128 . In particular, as illustrated in  FIG. 1 , the first notch  133  is formed in substantially a “V” shape and the other end of the integral push ring  128  is formed in an elliptical shape, so that they make two-point contact. Therefore, left and right movement of the first head support block  132  is prevented, and the central axis of the integral push ring  128  normally coincides with the center of the first notch  133  so as to make it move only in the forward and backward direction (the longitudinal direction of the head  10 ). 
     In addition, in order to move the first push rod  126  in the longitudinal direction thereof, a female screw (not shown) is formed on an inner wall of the first handle  124  and a male screw (not shown) is formed on an outer surface of the first push rod  126 . Next, the basic principle of operation of the first handle  124  will be described. The female screw of the first handle  124  and the male screw of the first push rod  126  are screwed into each other. Therefore, if the first handle  124  rotates, the first push rod  126  moves forward or backward in the longitudinal direction thereof. 
     Further, the first push rod  126  includes a first support section so as to press the first push rod  126  to be retreated in the longitudinal direction (to be moved in the direction of the first handle  124 ). In the present embodiment, the first support section illustrates a first compression spring  123  mounted on the first push rod  126 . One end of the first compression spring  123  is supported by a first spring seat portion  125  formed integrally on the first push rod  126 , and the other end thereof is supported by a fixed guide  112 . As a result, an axial force normally acts on the first handle  124  by an elastic force of the first compression spring  123 , so that backlash generated from the screwed portion inside of the first handle  124  is removed. Therefore, so called a backlash phenomenon can be prevented by the first compression spring  123 . 
     The second fine adjustment section that shifts the second head support block  134  in the transverse direction of the head unit  10  includes a driven beam  136  formed integrally with the second head support block  134 , a second push block  118  of which one end is fixed to a second push rod  106  and the other contacts the driven beam  136  so as to press the second head support block  134  in the transverse direction, the second push rod  106  supported by a plurality of fixed guides  108 ,  110 ,  112 ,  114 ,  116  and  117  fixed on the base plate  102 , and the second handle  104  fixed to one end of the second push rod  106  so as to move the second push rod  106  in the longitudinal direction. 
     The second push block  118  has a sloping side with a cross section of substantially triangular or trapezoidal shape. Therefore, if the second push block  118  moves forward, the driven beam  136  can be retreated by the sloping side in a direction away from the second push block  118  in the transverse direction of the head unit  10 . The tip of the driven beam  136  is preferably rounded to prevent damage by friction with the second push block  118 . At this time, the driven beam  136  comes into contact with the sloping side of the second push block  118 , in a state protruding outward of the second head support block  134 . The second push block  118  is formed integrally in the other end portion of the second push rod  106  which is disposed at a given interval with the head unit  10 . 
     Further, the second push rod  106  includes a second support section so as to press the second push rod  106  to be retreated in the longitudinal direction (to be moved in the direction of the second handle  104 ). In the present embodiment, the second support section illustrates a second compression spring  120  mounted on the second push rod  106 . One end of the second compression spring  120  is supported by a second spring seat portion  122  formed integrally on the second push rod  106 , and the other end thereof is supported by a fixed guide  116 . As a result, the axial force normally acts on the second handle  104  by the elastic force of the second compression spring  120 , so that backlash generated from the screwed portion inside of the second handle  104  is removed. Therefore, the backlash phenomenon can be prevented by the second compression spring  120 . 
     The first and second support sections are not limited to the ones illustrated in the embodiments of the present invention, but a variety of modifications are possible by applying the techniques known in the art. 
     In addition, the second head support block  134  includes a first reaction force member  138  and a second reaction force member  142 . The second reaction force member  142  opposed to the second push block  118  applies a reaction force to the second head support block  134  in a direction opposite to the press direction of the second push block  118 , and the first reaction force member  138  opposed to the second head support block  134  in the longitudinal direction applies a reaction force to the second head support block  134  in a direction orthogonal to the second reaction force member  142 . Springs (not shown) for applying the reaction force are installed inside of the first reaction force member  138  and the second reaction force member  142 , and a first reaction force protrusion  140  and a second reaction force protrusion  144  are coupled to the end portions of the springs. 
     The first reaction force protrusion  140  and the second reaction force protrusion  144  disposed at right angles to each other contact the end face and the side face of the second head support block  134 , respectively. 
     Accordingly, the first reaction force member  138  and the second reaction force member  142  provide the reaction force respectively against the pressing force applied to the first head support block  132  and the second head support block  134  by the first handle  124  and the second handle  104 , so that it is possible to hold an adjusted position of the head unit  10 . 
     The head alignment assembly  100  according to the first embodiment of the present invention has a configuration basically as described above. Hereinafter, the process of fine adjustment of the head unit  10  by the head alignment assembly  100  having such a configuration will be described. 
     It is possible to fine-adjust the position of the head unit  10  at every predetermined time or if abnormality is found on the printed matter. Especially if a camera that can photograph the print out result, in which an image, for example, is printed by the head section, is installed additionally in the printer, it is possible to fine-adjust the head unit  10  more finely than with a naked eye. 
     The image for fine-adjustment is printed by operating the printer for fine adjustment and the printed image is photographed by a camera, and then a deviation of the head unit  10  deviating from the reference position is measured by comparing the photographed image and the stored image. After that, based on the measured deviation, the operator corrects the head unit  10  by rotating the first handle  124  and the second handle  104 . 
     After correcting the position of the head unit  10 , the image is printed again, and the printed image is photographed by the camera, and then the deviation of the head unit  10  deviating from the reference position is measured again by comparing the photographed image and the stored image. After that, based on the measured deviation, the moving direction and moving amount of the first push rod  126  and the second push rod  106  by the first handle  124  and the second handle  104  are checked again. 
     When fine adjustment is completed by repeatedly carrying out the above processes, print out work is started again. If a locking device is additionally installed on the first handle  124  and second handle  104 , it is preferable to suppress the deviation generated in the head unit  10  by preventing the rotation of the first and second handles  124  and  104  by the locking device after completing fine adjustment. 
     Next, with reference to  FIGS. 3 and 4 , another head alignment assembly  101  according to a second embodiment of the present invention will be described. The head alignment assembly  101  is basically the same as the head alignment assembly  100  of the first embodiment. However, compared to the first embodiment, the first reaction force member  138  and the second reaction force member  142  are replaced by a slope reaction force member  150 , and a separate push ring  158  is employed instead of the integral push ring  128 , so that the separate push ring  158  is indirectly pressed through a first push block  154  formed integrally with the first push rod  126 . Further, the positions and structures of the first and second support sections are different, and a guide slot  103  formed so as to guide the second push block  118  is additionally provided. 
     It is possible to configure the slope reaction force member  150  by integrating the first reaction force member  138  and the second reaction force member  142  of the head alignment assembly  100  of the first embodiment into one mechanism by pressing the corner of the second head support block  134  in diagonal direction. Further, for this, it is preferable that a seat portion where the end portion of a diagonal reaction force protrusion  152  of the slope reaction force member  150  comes into contact be formed on the corner of the second head support block  134 . 
     Further, one end of the first push block  154  is formed integrally with one end of the first push rod  126 , and the other end thereof is provided with a second notch  156  corresponding to the first notch  133 . One end of the separate push ring  158  contacts the second notch  156  of the first push block  154  and the other end thereof contacts the first notch  133  of the first head support block  132 . Accordingly, both ends of the separate push ring  158  make two-point contacts respectively with the first notch  133  and the second notch  156 , so that the central axis of the separate push ring  158  normally coincides with the central axes of the first notch  133  and the second notch  156 . In addition, the moving length of the separate push ring  158  in the longitudinal direction is limited within a predetermined range (that is, the length of the internal slot) by the fixed pin  130 . Accordingly, the first push block  154  formed integrally with the first push rod  126  by forward movement of the first push rod  126  moves in the longitudinal direction. As a result, the separate push ring  158  is pressed to be moved. In addition, the first head support block  132  may be pressed by the separate push ring  158  to move in the longitudinal direction. On the other hand, if the first push rod  126  moves backward, the first head support block  132  is retreated by the slope reaction force member  150 . 
     In addition, the first and second support sections may be one short first compression spring  153  and one short second compression spring  151 . The first compression spring  153  is mounted on the first push rod  126  between the first push block  154  and the fixed guide  112 , and the second compression spring  151  is mounted on the second push rod  106  between the second push block  118  and the fixed guide  116 . Accordingly, it is possible to hold the positions of the first push rod  126  and the second push rod  106  by the support of the first and second compression springs against the reaction force of the slope reaction force member  150 . 
     Further, the second push block  118  has one side formed of a plane parallel to the longitudinal direction of the second push rod  106 , and a guide slot  103  that contacts the plane of the second push block  118  is formed on the base plate  102 . 
     Accordingly, the second push block  118  is supported by the guide slot  103 , so it is possible to prevent deformation of the second push rod  106  due to the reaction force of the slope reaction force member  150  acting continuously through the driven beam  136 . 
     Next, with reference to  FIG. 5 , a head alignment assembly  105  according to a third embodiment of the present invention will be described. The head alignment assembly  105  according to the present embodiment is basically the same as the head alignment assembly  100  of the first embodiment. However, compared to the first embodiment, the head alignment assembly  105  includes an eccentric bearing  172  installed to support the second push block  118 , a second support section  160  installed to support and press the second push rod  106 , a coupler  174  connecting the first handle  124  and the first push rod  126  and a coupler  180  connecting the second handle  104  and the second push rod  106 . In addition, a driven beam  184  separated from a second head support block  182  is employed instead of the driven beam  136  formed integrally on the second head support block  134 . 
     The eccentric bearing  172  contacts a surface opposite to the sloping side of the second push block  118  in contact with the driven beam  184 . Accordingly, the eccentric bearing  172  plays a role of preventing the deformation of the second push rod  106  generated by the first and second reaction force members  138  and  142 , likewise with the guide slot  103 . The eccentric bearing  172  is rotatably mounted on an eccentric bolt  170  fixed on the base plate  102 . Accordingly, it is possible to change the position of the eccentric bearing  172  by rotating the eccentric bolt  170 . Therefore, it is possible to adjust the fine interval between the second push block  118  and the eccentric bearing  172  by the eccentric bolt  170 . 
     In addition, the second head support block  182  is formed in substantially an ‘L’ letter shape, as illustrated in  FIG. 5 , and the driven beam  184  is installed in the bent portion thereof. 
     The driven beam  184  is a substantially elliptical ring having a slit therein, and an upper portion of a driven beam pin  186  of which a lower end is fixed on the base plate  102  is inserted into the slit. The driven beam pin  186  has a cross section of substantially rectangular or square shape so as to guide the driven beam  184  to move in a straight line. In addition, one end of the driven beam  184  comes into contact with the second head support block  182 , and the other end of the driven beam  184  comes into contact with the sloping side of the second push block  118 . Especially, a driven bearing  137  may be installed at the end portion of the driven beam  184  so as to provide a smooth contact between the second push block  118  and the driven beam  184 . 
     The second support section  160  includes a support casing  161  having a space therein, and a second compression spring  162  which is installed in the support casing  161  to press one end of the second push rod  106  inserted into the casing. Further, an adjustment bolt  168  for adjusting the reaction force of the second compression spring  162  may mounted on the support casing  161  on the opposite side of the second push rod  106 . In this case, washers  164  and  166  are arranged at both ends of the second compression spring  162  to prevent the second compression spring  162  from being rotated by the rotation of the adjustment bolt  168 . The outside ends of the washers  164  and  166  are in contact with one end of the second push rod  106  and the adjustment bolt  168  respectively. 
     The couplers  174  and  180  are used for the case that the handle axes  107  and  127  of the first and second handles  104  and  124  are protruded lengthwise. That is, the coupler  174  connects the second push rod  106  and the handle axis  107 , and the coupler  180  connects the first push rod  126  and the handle axis  127 . 
     The couplers  174  and  180  connect one end of the push rod and one end of the handle axes by coupling bolts  176  and  178 . 
     Next, with reference to  FIG. 6  and  FIG. 7 , a head alignment assembly  200  according to a fourth embodiment of the present invention will be described. The head alignment assembly  200  is basically the same as the head alignment assembly  100  of the first embodiment. However, compared to the first embodiment, when head units  12  and  14  are disposed in a row in the longitudinal direction on a base plate  202 , or the distance between the central axes of two head units is so short that the space is not enough for the first and second push rods to be inserted, first and second push rods  252  and  276 ; and  206  and  230  are installed in parallel with each other on different levels. 
     For this, the head alignment assembly  200  includes two first head support blocks  262  and  286 , two second head support blocks  266  and  290 , a first fine adjustment section for allowing the displacement of the head support blocks  262  and  286  in the longitudinal direction of the head unit  10 , and a second fine adjustment section for allowing the displacement of the second head support blocks  266  and  290  in the transverse direction orthogonal to the longitudinal direction of the head units  12  and  14 . 
     The first and second push rods  252  and  276 ; and  206  and  230  are supported by fixed guides  208 ,  210 ,  212 ,  214 ,  216 ,  218 ,  220 ,  222 ,  224 , and  226  which are installed on the base plate  202  in parallel with each other on different levels. 
     Integral push rings  258  and  282  have height different from each other so as to be fixed integrally to the first push rods  252  and  276  with different heights. That is, the height of the integral push ring  258  on the side close to the first handles  250  and  274  is lower than the height the integral push ring  282  on the far side. 
     In addition, it is preferable to form the length of the fixed pins  260  and  284  differently depending on the heights of the integral push rings  258  and  282 . 
     The second push blocks  236  and  242  have the thickness different so as to be fixed integrally to the second push rods  206  and  230  with different heights. That is, the thickness of the second push block  236  close to the second handles  204  and  228  is smaller than the thickness of the second push block  242  on the far side. 
     Besides of these, the configuration of first reaction force members  270  and  294 , second reaction force members  272  and  296 , first compression springs  256  and  280 , first spring seat portions  254  and  278 , second compression springs  234  and  240 , second spring seat portions  232  and  238 , driven beams  268  and  292 , and the second head support blocks  266  and  290  is the same as the first embodiment, so detailed description thereof is omitted. 
     Further, in the first head support blocks  262  and  286 , it is also possible to increase the thickness of the first head support block  286  disposed far from the first handles  250  and  274 , as illustrated in  FIG. 6 . The shape of the first notches  264  and  288  formed on the first head support blocks  262  and  286  is the same as the first embodiment. 
     Although the present invention has been described in connection with the exemplary embodiments illustrated in the drawings, it is only illustrative. It will be understood by those skilled in the art that various modifications and equivalents can be made to the present invention. Therefore, the true technical scope of the present invention should be defined by the appended claims. 
     DESCRIPTION OF REFERENCE NUMERALS IN DRAWINGS 
     
         
           10 , 12 , 14 : head unit 
           100 , 101 , 105 , 200 : head alignment assembly 
           102 , 202 : base plate 
           103 : guide slot 
           104 , 204 , 228 : second handle 
           106 , 206 , 230 : second push rod 
           107 , 127 : handle axis 
           108 , 110 , 112 , 114 , 116 , 208 , 210 , 212 , 214 , 216 , 218 , 220 , 222 , 224 , 226 : fixed guide 
           118 , 236 , 242 : second push block 
           120 , 151 , 162 , 234 , 240 : second compression spring 
           122 , 232 , 238 : second spring seat portion 
           123 , 153 , 256 , 280 : first compression spring 
           124 , 250 , 274 : first handle 
           125 , 254 , 278 : first spring seat portion 
           126 , 252 , 276 : first push rod 
           128 , 282 , 258 : integral push ring 
           130 , 260 , 284 : fixed pin 
           132 , 262 , 286 : first head support block 
           133 , 264 , 288 : first notch 
           134 , 182 , 266 , 290 : second head support block 
           136 , 184 , 268 , 292 : driven beam 
           137 : driven bearing 
           138 , 270 , 294 : first reaction force member 
           140 : first reaction force protrusion 
           142 , 272 , 296 : second reaction force member 
           144 : second reaction force protrusion 
           150 : single reaction force member 
           152 : diagonal reaction force protrusion 
           154 : first push block 
           156 : second notch 
           158 : separate push ring 
           160 : second support section 
           161 : support casing 
           164 , 166 : washer 
           168 : adjustment bolt 
           170 : eccentric bolt 
           172 : eccentric bearing 
           174 , 180 : coupler 
           176 , 178 : coupling bolt 
           186 : driven beam pin. 
       
    
     CONCLUSION 
     All of the various embodiments or options described herein can be combined in any and all variations. While the invention has been particularly shown and described with reference to some embodiments thereof, it will be understood by those skilled in the art that they have been presented by way of example only, and not limitation, and various changes in form and details can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. 
     All documents cited herein, including journal articles or abstracts, published or corresponding U.S. or foreign patent applications, issued or foreign patents, or any other documents, are each entirely incorporated by reference herein, including all data, tables, figures, and text presented in the cited documents.