Patent Publication Number: US-7587976-B2

Title: Printing apparatus having fixing mechanism including air pipe assembly

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to printing, and particularly to a printing apparatus comprising a fixing mechanism. 
   2. Description of Related Art 
   Nowadays, printing mainly includes silk-screen printing, relief printing, planographic printing, gravure printing, etc. Compared to other printing methods, silk-screen printing is more popular because of its facility and cheapness. 
   In the method of silk-screen printing, first, a silk-screen having a large number of meshes is woven to cover the printing objects. Sensitive glue is spread on the silk-screen to block the meshes and forms a sensitive layer on the silk-screen. A negative having predetermined designs/characters is covered on the silk-screen, and the silk-screen and the negative are exposed together. Thus, the sensitive layer of the silk-screen is exposed and solidified except the part covered by the designs/characters of the negative. The silk-screen is then washed, the solidified part of the sensitive layer remains on the silk-screen while the part covered by the designs/characters of the negative is removed. In this way, the meshes corresponding to the designs/characters of the negative are opened again, and the silk-screen is completed. 
   In use, the silk-screen covers a printing object, and ink is spread on the silk-screen. The ink passes the open meshes and adheres to the object, thus the designs/characters of the negative is formed on the object. The silk-screen is then removed after printing, thus the printing operation is completed. 
   In the aforementioned method, since the ink has glutinosity, the object can be glued to the silk-screen in printing. Thus, the object may be moved or damaged when the silk-screen is removed, and the printing quality is then decreased. In a typical printing method, the object is fixed on a worktable via glue. The glue has higher glutinosity than that of the ink, thus prevents the object from being moved by the silk-screen. However, additional cost is required for the glue and it is difficult to remove the glue after printing. Thus, productive efficiency is decreased. 
   Therefore, a fixing mechanism used to print and a new printing apparatus are desired in order to overcome the above-described shortcomings. 
   SUMMARY OF THE INVENTION 
   A fixing mechanism includes a base, an air pump and an air pipe assembly. The base defining a connecting hole and a locating groove therein. The air pipe assembly includes a first pipe communicating with the connecting hole, a second pipe connected to the pump and communicating with the first pipe, and a third pipe communicating with the first pipe and the second pipe. 
   A printing apparatus includes a worktable, a silk-screen and a fixing mechanism. The worktable includes a base, a bracket and a post. One end of the silk-screen is rotatably connected to the bracket and another end of the silk-screen is held by the post. The fixing mechanism includes a base, a pump and an air pipe assembly, the air pipe assembly includes a first pipe communicating with the base, a second pipe connected to the pump and communicating with the first pipe, and a third pipe communicating with the first pipe and the second pipe. 
   Other novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Many aspects of the fixing mechanism and the printing apparatus can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the fixing mechanism and the printing apparatus. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       FIG. 1  is a schematic view of a printing apparatus in accordance with a present embodiment. 
       FIG. 2  is an enlarged view of a bracket of the printing apparatus shown in  FIG. 1 . 
       FIG. 3  is an enlarged view of a post of the printing apparatus shown in  FIG. 1 . 
       FIG. 4  is an exploded view of a base of a fixing mechanism of the printing apparatus shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a printing apparatus  100  in accordance with a present embodiment is provided. The printing apparatus  100  includes a worktable  1 , a fixing mechanism  2  mounted on the worktable  1  and a silk-screen  3  rotatably mounted on the worktable  1 . 
   The worktable  1  includes a base  10 , two brackets  20  and two posts  30 . The base  10  includes an approximately rectangular bottom board  12  and an approximately rectangular carrying board  14  located on a central portion of the bottom board  12 . The carrying board  14  defines a plurality of first locating holes (not shown) therein. The brackets  20  and the posts  30  are respectively fixed on four corners of the bottom board  12 . 
   Also referring to  FIG. 2 , each bracket  20  includes a prism member  22 , a first bolt  24  and a hinge assembly  26 . The prism member  22  defines an adjusting aperture  222  in its side portion and a first thread hole  224  in its top portion. The first thread hole  224  runs along an axis of the prism member  22  and communicates with the adjusting aperture  222 . The first bolt  24  includes a first head portion  242  for adjusting its position and a first thread portion  244  corresponding to the first thread hole  224 . 
   The hinge assembly  26  includes a mounting member  262 , an axle  263  and a hanging member  264 . The mounting member  262  includes a screw end  2622  and a hinge end  2624  opposite to the screw end  2622 . The screw end  2622  defines a second thread hole (not labeled) configured for receiving the thread portion  244  therein. The hinge end  2624  defines a containing groove  2625 , and two walls  2626  corresponding to the containing groove  2625  are formed at the hinge end  2624 . Each wall  2626  defines a first axle hole (not labeled) corresponding to the axle  263  therethrough. The hanging member  264  is a triangular prism defining a second axle hole (not labeled) corresponding to the first axle holes. 
   In the assembly process of the bracket  20 , the axle  263  is inserted into the first axle holes and the second axle hole to mount the hanging member  264  to the mounting member  262 . The thread portion  244  is screwed into the first thread hole  224  and the second thread hole of the screw end  2622 , thus the hinge assembly  26  is movably mounted on the first bolt  24 . 
   Also referring to  FIG. 3 , each post  30  includes a pedestal member  32 , a second bolt  34  mounted on the pedestal  32  and a nut  36  engaging with the second bolt  34 . The pedestal member  32  is a prism shorter than the prism member  22  of the bracket  20 . The pedestal member  32  defines a first connecting hole  322  in its side portion and a third thread hole (not labeled) in its top portion. The third thread hole communicates with the first connecting hole  322 . The second bolt  34  includes a second head portion and a second thread portion  344  corresponding to the third thread hole. The second bolt  34  defines an adjusting hole  346  in a central portion of the head portion  342 ; the adjusting hole  346  extends along the axis of the second bolt  34  and runs through the second bolt  34 . In this way, the adjusting hole  346  communicates with the first connecting hole  322  via the third thread hole when the second bolt  34  is screwed into the third thread hole. The nut  36  is, correspondingly, configured to be screwed the bolt  34 . 
   Referring to  FIG. 1  and  FIG. 4 , the fixing mechanism  2  includes a base  50 , an air pipe assembly  60  and an air pump  70  connected to the base  50  via the air pipe assembly  60 . The base  50  includes an approximately rectangular locating board  52 , a fixture  54  located on the locating board  52  and a gasket  56  received in the locating board  52 . The locating board  52  defines a second connecting hole  522  in a side portion thereof, a suction recess  524  and a plurality of second locating holes  526 . The second connecting hole  522  extends to a central portion of the locating board  52 . The locating board  52  also defines a first air hole  528  in a central portion of a bottom of the suction recess  524  and a loop groove  529  surrounding the first air hole  528 . The first air hole  528  communicates with the second connecting hole  522  at a central portion of the locating board  52 . The second locating holes  526  are defined at each corner of the locating board  52 . Some second locating holes  526  are configured for corresponding to the first locating holes defined in the carrying board  14 . The gasket  56  is embedded in the loop groove  529 . 
   The fixture  54  is an approximately rectangular board with a size smaller than that of the locating board  52 . The fixture  54  defines a rectangular locating groove  542 , four third locating holes  544 , and a second air hole  546  therein. The locating groove  542  is defined in a central portion of the fixture  54 . The third locating holes  544  are configured to be respectively adjacent at four corners of the locating groove  542  and correspond to four second locating holes  526 . The second air hole  546  communicates with the locating groove  542  and corresponds to the first air hole  528  of the locating board  52 . 
   The air pipe assembly  60  includes a first pipe  62 , a second pipe  64  and a closeable third pipe  66 . The first pipe  62 , the second pipe  64  and the third pipe  66  are connected to each other and communicate with each other at a same joint, thus the air pipe assembly  60  is configured to be Y-shaped. 
   The silk-screen  3  is rectangular shaped and includes a large number of meshes (not labeled). The meshes can be used to form the designs/characters requiring to be printed to objects. 
   In assembly, the two brackets  20  are respectively fixed on two adjacent corners of the bottom board  12 . The two posts  30  are respectively mounted on other two corners of the bottom board  12 . The locating board  52  is placed on the carrying board  14  of the base  10 , some mounting members (not shown) such as bolts are screwed into the second locating holes  526  which corresponds to the first locating holes, and then screwed into the first locating holes for fixing the locating board  52  on the carrying board  14 . The fixture  54  is placed on the locating board  52 , some mounting members (not shown) such as bolts are screwed into the third locating holes  544 , and then screwed into the second locating holes  526  corresponding to the third locating holes  544  to fix the fixture  54  on the locating board  52 , with the gasket  56  abutting the fixture  54 . 
   The second air hole  546  is aligned with the first air hole  528 , thus communicates with the second connecting hole  522 . The first pipe  62  is connected to the air pump  70 , the second pipe  64  communicates with the second connecting hole  522 , and the third pipe  66  communicates with at least one first connecting hole  322 . One side of the silk-screen  3  is fixed to the hanging members  264  of the hinge assembly  26  via gluing or soldering, and an opposite side of the silk-screen  3  is held by the second bolts  34  of the two posts  30 . In this way, the silk-screen  3  covers the head portion  342  and the adjusting hole  346  of each bolt  34 . The air pipe assembly  60  communicates with the first connecting hole  322  and the second connecting hole  522 , and further communicates with the adjusting hole  346 , the first air hole  528  and the second air hole  546  to form an air container (not labeled) communicating with the air pump  70 . The silk-screen  3  can be rotated around the axle  263 , and highness of the silk-screen  3  can be adjusted via the first bolts  24  and the second bolts  34 . 
   In use, an object (not shown), such as paper, is placed into the locating groove  542 . The silk-screen  3  is rotated to cover the object and close the adjusting holes  346 . The air pump  70  is turned on to deflate air of the second connecting hole  522 , the first air hole  528  and the second air hole  546 . In this way, an air pressure in the air container is decreased, and the object is absorbed in the locating groove  542 , thus the object can be conveniently printed. After printing, the covering silk-screen  3  is rotated and removed from the bolts  34  and the object. When the silk-screen  3  is removed from the bolts  34 , the adjusting holes  346  are opened, allowing air to enter into the air container. The air pressure in the air container resumes, and the printed object can be removed. 
   Understandably, the locating groove  542  can be in other shapes. A location of the silk-screen  3  can be adjusted via the first bolts  24  and the second bolts  34  to adapt objects having different thickness. The third pipe  66  can also be opened or closed by other means, such as adjustable clamp to adjust the air pressure in the container. Accordingly, the adjusting holes  346  and the first connecting holes  322  can be omitted. 
   It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.