Flat article feeding apparatus
BACKGROUND OF THE INVENTION 
     This invention relates to an apparatus for handling flat articles, such as an envelope and a postcard, and more particularly, to a flat article feeding apparatus which successively feeds flat articles from a stacker, one by one. 
     In a conventional flat article feeding apparatus, a suction chamber is arranged at a position confronting flat articles which are accumulated in a stacker. An endless suction belt, having pierced holes, is driven around the suction chamber to pick up the flat articles, one by one, from the stacker. The flat article thus picked up is caught in the nip and pinched between a pair of transfer belts aligned with and confronting the output end of the suction belt. 
     The construction of such a conventional flat article feeding apparatus is schematically disclosed, for example, in U.S. Pat. No. 3,604,702, and particularly in its FIG. 2. In the disclosed feeding apparatus, an entrance space at the front of the pair of transfer belts is enlarged to ensure receiving the flat articles as they are delivered from the suction belt. Such a structure of the transfer belts is advantageous in that, even if there is a bent tip on the fed flat article delivered from the suction belt, the fed flat article can be pinched securely between the pair of the transfer belts. 
     The conventional flat article feeding apparatus, however, is defective in the following respects. In general, the suction belt and transfer belts are driven at a certain constant speed at which the flat article is transferred. On the other hand, as described above, in order to pinch the fed flat article accurately, the entrance space of the transfer belts is enlarged. For example, one of the pair of transfer belts is opened at a certain angle with respect to the transfer direction as shown in FIG. 2 of U.S. Pat. No. 3,604,702. Assuming that the transfer speed is V and the angle if θ, of the one opened belt at the entrance of the transfer belt, a speed of transfer direction component of the opened belt is represented by V cos θ, which is surely smaller than V. As a consequence, when the flat article is delivered from the suction belt driving at the transfer speed V, and if its leading tip end is bent, and the tip collides against the opened belt of the transfer belts, a large pressure is exerted on the leading end or tip of the flat article due to the difference between its speed V and the opened belt&#39;s speed V cos θ in the transfer direction component. This is apt to cause a mutiliation of the article, a misoperation, and a jam. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the invention to provide a flat article feeding apparatus which can securely feed out a flat article without mutilating it, causing a misoperation, and a jam, even when the flat article is bent at its leading end or tip. 
     According to the invention, a flat article feeding apparatus has a stacker for accumulating flat articles, in a standing state. A main suction chamber confronts the sides of the flat articles as they are accumulated in the stacker. A perforated suction belt is designed to move around the main suction chamber for picking up the flat articles, one by one. A pair of transfer belts are positioned for transferring the flat articles as they are delivered from the suction belt, the transfer belts pinching the articles therebetween. An intake belt is provided between the suction belt and the transfer belts and is tilted by an angle θ, with respect to the flat article transfer direction. Or, fins may be mounted on a roller which supports the intake belt in order to push bent tip ends into alignment. The speed V 1  of the intake belt or fins is set equal to V 1  ≧(V 2  /cos θ). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This invention will now be described in detail with reference to the accompanying drawings, in which: 
     FIG. 1 is a top plan view of an embodiment of this invention; 
     FIG. 2 is a perspective view of the flat article feeding apparatus illustrated in FIG. 1; and 
     FIG. 3 is another top plan view for explaining the operations of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, flat articles 1 to be fed out are accumulated in a standing state in a stacker 2. A main suction chamber 3 is provided at a side confronting the sides of the flat articles 1. The main suction chamber 3 has a flat side containing air suction holes on a flat article side, and chamber 3 is connected to a vacuum pump (not shown). Three rollers 5, 6 and 7 are arranged around the perimeter of the main suction chamber 3 and have an endless perforated suction belt 4, which surround the main suction chamber 3. The perforated suction belt 4 has pierced holes 21 and 22 (FIG. 2), at a certain pitch, which are designed to move around the main suction chamber 3 in a direction 16. 
     When the belt 4 comes to a position at which the holes 21 or 22 of the suction belt 4 are aligned with the air suction holes of the main suction chamber 3, the left most (as viewed in FIG. 1) flat article 1a is delivered from the stacker 2, and is fed out toward a transfer belt 9 and intake belts 13 and 13&#39;. 
     An auxiliary suction chamber 8 is provided below the roller 6 to prevent a simultaneous feed-out of flat articles by forming a suction against a trailing end or tail tip of the next flat article in stack 1. 
     The description will proceed next to a flat article transferring structure. A pair of transfer belts 9 and 10 are entrained respectively on rollers 11 and 12, and extend in a direction identical with the flat article feeding direction 17. The pair of transfer belts 9 and 10 are designed to pinch therebetween and to carry the flat article as it is delivered from the suction belt 4 and to transfer it in forward direction 17. 
     As is clearly seen in the drawings, of these two transfer belts, the transfer belt 9 extends further than the other transfer belt 10 extends toward suction belt 4. As can be best seen in FIG. 2, two intake belts 13 and 13&#39; are entrained around a pair of rollers 14 and 15 in the vicinity of the upper and lower ends of the rollers. The belts 13 and 13&#39; are arranged to open outwardly from belt 9 by an angle θ (FIG. 1), with respect to the flat article feed-out direction 17 so as to enlarge the entrance to the space between belts 9, 10. 
     The roller 14 near the suction belt 4 feed-out part is adapted to rotate the belts 13 and 13&#39; in a direction 18 in FIG. 1. Roller 14 has a plurality of fins 24 extending perpendicularly from its peripheral surface. The fins 24 are provided to push the leading end or tip of the flat article toward the transfer belt 9 (see FIG. 3). 
     With such a construction, the moving speed of the intake belts 13 and 13&#39; is set to be equal to or more than (1/cos θ) times as fast as the transfer speed, i.e., the moving speed of the suction belt 4 or the transfer belts 9 and 10. The respective rollers 5, 11, 12 and 14 are driven by drive means (not shown). 
     In operation, the flat articles accumulated in the stacker 2 are fed out, one by one, in accompanyment with the rotation of the suction belt 4. After this, the flat article carried by belt 4 is guided by the fins 24 or the intake belts 13 and 13&#39;, and is finally transferred through the transfer belts 9 and 10 to a next handling process station. 
     When the fed flat article is bent at the leading end or tip (FIG. 3), the tip reaches the fins 24 or the intake belts 13 and 13&#39;, as indicated by flat articles 19 and 20, in accompanyment with the rotation of the suction belt 4. In the case of the flat article 19, the leading end or tip of the flat article is pushed toward the transfer belt 9 by the fins 24 on the roller 14, which rotates more rapid than the moving speed of the perforated suction belt 4. Thus, the flat article can be transferred to the transfer belts 9 and 10 without pressure being exerted at the leading end or tip of the flat article. On the other hand, in the case of the flat article 20, the leading end or tip of the flat article is in contact with the belts 13 and 13&#39;. Since the speed of these belts 13 and 13&#39; is (1/cos θ) times as fast as the speed of the suction belt 4, the flat article can be also transferred to the transfer belts 9 and 10 without the pressure being exerted at the leading end or tip of the flat article. 
     As described in the foregoing specification, the invention contributes to an improvement in flat articles handling by providing a flat article feeding apparatus which can stably feed out flat articles without multilating them and without misoperation, or a jamming of the flat article, even when the fed out flat article is bent or apt to bend at its leading end or tip. 
     Those who are skilled in the art will readily perceive how to modify the invention. Therefore, the appended claims are to be construed to cover all equivalent structures which fall within the true scope and spirit of the invention.