Abstract:
A single tray is used to collate the printed papers from a printer. The tray is moved to different positions to receive the printed papers. Thus, the printed papers are collated into different stacks. The movement of the tray can be linear or curvilinear. The circular movement can collate the printed papers into more than two stacks.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to collators for printers. 
     Among the peripheral equipment for a computer, a printer is an important one. For the output of the printer, collating is an important function. Conventional collators customarily use a multiple tray structure to sort the printed sheets. Such a design is very complicated and hence very costly. 
     A conventional multiple tray collator typically has the following operation. If a stack of document has, say, 5 pages, the pages are numbered as #1, #2, #3, #4 and #5. If three copies are to be outputted, the output can have at least the three following modes: 
     (1) Select in the first tray three copies #1, #1, #1; in the second tray three copies #2, #2, #2; in the third tray three copies #3, #3, #3; in the fourth tray three copies #4, #4, #4; and in the fifth tray three copies #5, #5, #5. Then the copies in each tray are taken out and manually collate them in the order #1, #2, #3, #4, #5 into three stacks. 
     (2) Select in the first tray five pages #1, #2, #3, #4, #5; in the second tray five pages #1, #2, #3, #4, #5; in the third tray five pages #1, #2, #3, #4, #5. 
     (3) Select different numbers for different pages. For instance: the first tray has five pages, #1, #2, #3, #4, #5; the second tray has three pages #1, #2, #3; and the third tray has four pages #1, #3, #4, #5, 
     In all the foregoing output traditional methods, a multiple tray collating equipment is used. The structure is very complicated, costly and unreliable. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to use a single tray to collate papers for a printer. Another object of this invention is to provide a collator which simplifies the structure, reduces the cost and is more reliable. Still another object of the invention is to miniaturize the collator to be lighter and thinner. 
     These objects are achieved by using a single tray and moving the tray in different positions to collate the printed papers into different stacks. The movement may be a linear one or a circular one. The printed papers can be collated into multiple numbers of stacks. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A shows the block diagram of a conventional collator; 
     FIG. 1B shows the page dispensing scheme of a conventional collator; 
     FIG. 1C shows the interconnection among a computer, a printer and a sorter. 
     FIG. 2A shows the design of the collator based on the present invention; 
     FIG. 2B allows the basic operation of the collator based on the present invention; 
     FIG. 2C shows the resulting stacking of the pages of the present invention. 
     FIG. 3A shows a second embodiment of a collator of the present invention; 
     FIG. 3B shows the operation of the second embodiment; 
     FIG. 3C shows the resulting stacking of the papers of the second embodiment; 
     FIG. 3D shows a third embodiment of the present invention; 
     FIG. 3E shows a fourth embodiment of the collator of this invention. 
     FIG. 4A shows a fifth embodiment of the collator of the present invention; 
     FIG. 4B shows the operation of the fifth embodiment; 
     FIG. 4C shows the resulting stacking of the pages of the fifth embodiment; 
     FIG. 4D shows a mechanism to effect the fifth embodiment; 
     FIG. 4E shows another mechanism to effect the fifth embodiment; 
     FIG. 4F shows still another mechanism to effect the fifth embodiment. 
     FIG. 5 shows N stacks after collation by means of the fifth embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1A shows a block diagram of a printer system. A digital scanner  12  sends its data to a printing device  14  to finish a printed output. The printing device has a central processing unit (not shown), which controls the operation of the collator or sorter  18 . A control panel allows a user to select the printer requirements. 
     FIG. 1B shows the structure of a prior art collator of a printer. After finishing printing, the printed papers P are dispatched to the collator. For the purpose of explanation, the collator shown has five trays: Tray #1, Tray #2, Tray #3, Tray #4 and Tray #5. The collator  18  dispatches the printed papers to the different trays according to the instruction from the central processing unit (CPU, not shown), which controls the vertical motion of the collator  18  to collect the printed papers. 
     FIG. 1C shows the connections among the connection between the printing device  142  with the computer  122  and the connection between the printing device  142  with the collator  182 . 
     FIG.  2 A and FIG. 2B show the first embodiment of the present invention. There is only one tray  28 , which is capable of moving back and forth in the V direction. A motor  22  pushes the push rod  24  according to instructions from the CPU and causes the tray  28  to move back and forth in the V direction. In FIG. 2A, the tray is in a first position and stacks the documents as stack  26 A. In FIG. 2B, the tray  28  is in a second position and stacks the second group of documents as stack  26 B. Stack  26 A and stack  26 B are staggered as shown in FIG. 2C, and are thus separated and collated. 
     FIG.  3 A and FIG. 3B shows a second embodiment of the present invention. Again, there is only one tray  38 , which can be pushed to move back and forth in the H direction. The motor  32  drives the guiding rod  34  to effect the reciprocating motion, according to control signals received from a CPU. FIG. 3A shows the tray  38  in a first position to collect the first group of papers P to form stack  36 A. FIG. 3B shows the tray  38  in a second position to collect the second group of papers to form stack  36 B. The documents in stack  36 A and stack  36 B are staggered as shown in FIG.  3 C. Thus the collating function is accomplished. 
     FIG. 3D shows a third embodiment of the present invention, which accomplishes the same result as FIG.  3 C. The collating tray  38  has a side wall  382 . At the top of the side wall is an axle C, to which a guide plate  384  is attached. The guide plate  384  can swing back and forth according to the control signal from a CPU. When the guide plate is in a first position and the angle between the guide plate  384  and the vertical wall  382  is zero, the papers dispatched from the source P are stacked up as document  36 A. When the guide plate  384  forms an angle, say  30  degrees, with the vertical wall  382 , the papers dispatched from the source P are stacked up as document  36 B. The documents  36 A and  36 B are staggered as shown in FIG. 3C, which is the result of the separating operation shown in FIG.  3 D. 
     FIG. 3E shows a fourth embodiment of the present invention which also can yields a result similar to that in FIG.  3 C. The reciprocating motion is produced by a rack and pinion motion. A rack  33  is attached to the tray  38  and a pinion  35  driven by a motor engages the rack  33  to produce the reciprocating motion along the H direction. The papers collected by the tray are sorted into two stacks as shown in FIG.  3 C. 
     FIG. 4A shows a fifth embodiment of the present invention. The tray  48  is pivoted at one end and is equipped with a slotted handle  44  with a slot  442 . A driving wheel  42  has a pin  422  protruded from the edge of the wheel surface through the slot  442 . When the wheel rotates, the pin  422  slides back and forth along the slot  442 , causing the tray to rotate back and forth with respect to the axis the pivot. The motor driven wheel rotates according to the control signal from the CPU. FIG. 4A shows the tray  48  in a first position to collect the papers from source P as stack  46 A. FIG. 4B shows the tray  48  in a second position to collect papers from source P as stack  46 B. Thus the documents are separated and collated. The wheel  42  can also be replaced with an eccentric wheel or a protruded wheel. 
     FIG. 4D shows a sixth embodiment of the present invention. At the exit port of the paper source P is placed a guide  41 , which has two side walls. The side walls can be tilted at different angles. In one position of tilt, the side walls  411  are as shown in solid line and guide the papers as stack  46 A. In a second position of tilt, the side walls  412  are as shown in dotted line and guide the papers as stack  46 B. Thus the two stacks are sorted as shown in FIG.  4 C. 
     FIG. 4E shows a seventh embodiment of the present invention. Here the tray  48  is pivoted at one end and attached to an arm  432  through a coupling  482 . The arm is actuated by turning on and off an electromagnet  43 . The force on the electromagnet causes the tray to rotate back and forth along an arc R. The tray  48  collects the documents and separates them as shown in FIG. 4 C. 
     FIG. 4F shows an eighth embodiment of the present invention. A pivoted paper receiving tray  48  is attached to a belt  454 , which is coupled to a driving motor through an eccentric idler  452 . The eccentricity of the idler  452  causes the tray  48  to move along the arc R. The other side of the tray opposite the belt  454  is pushed by a spring  484 . With this arrangement, the tray  48  can move back and forth. Papers are received by the tray during stationary positions. In this manner, the papers are collated as shown in FIG.  4 C. 
     FIG. 5 shows a ninth embodiment of the present invention to collate the papers into N number of stacks. In this scheme, the collecting tray is rotated N times in one cycle. For instance, if the tray is moved 30 degrees in every move, the collected papers are collated into 360/30=12 stacks. Any of the schemes shown in FIGS. 4A,  4 B,  4 D,  4 E and  4 F with circular distribution can be used to effect this multiple stack collator. 
     While the preferred embodiments of this invention have been shown and described, it will be apparent to those skilled in this art that various modifications may be made in the embodiments without departing from the spirit of the present invention. Such modifications are all within the scope of this invention.