Booklet maker

A low cost, high speed, high resolution laser printer method and apparatus for re-writable media is presented. A method for finishing of printed sheets into booklets is described. Novel mechanical operations permit the manufacture of a very low-cost, off-line booklet maker for use with desktop laser and ink jet printers. The technology can scale to medium-speed, in-line booklet manufacture. The method is novel because most of the finishing operations are performed on a sheet-by-sheet basis using precision paper positioning and a transverse tool carrier that cuts, scores, folds, punches, and staples the sheets. To form a finished saddle-stitched booklet, each sheet is cut to length determined by its sequence in the booklet and paper thickness, scored, punched (if required), folded, accumulated in a stack, and stapled. The sheet-wise method allows finishing operations to be done with low-cost tools and low actuation forces.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to electronic publishing and, more 
particularly, to the finishing of printed sheets into booklets. 
2. Description of the Related Art 
Electronic publishing demands more than a stack of paper in an output tray 
of a laser or ink jet printer. Typically, many sheets, duplex printed, 
must be bound into finished documents by a paper-handling accessory. 
Currently, machines exist to perform operations such as perfect binding, 
folding, trimming, saddle stapling, and hole drilling. These finishing 
operations are typically performed on many sheets at a time, requiring 
high forces and powerful motors. Such machines are expensive, 
$2,000-$10,000 depending on function, and often exceed the cost of desktop 
or office printers. As such, they are not well-suited to low-cost desktop 
finishing. 
The demands of electronic and desktop publishing are driving the need for a 
compact, low-cost, high-quality, and low- to medium-speed finishing 
machine suitable for use with desktop laser and ink jet printers. Prior 
art solutions to making booklets typically involve machines costing $4000 
or more for simple functions such as folding and stapling. They are bulky 
and require a long paper path to implement sequential finishing 
operations. Trimming and punching are performed on the assembled booklet, 
and this requires a cutter and power source capable of processing 20 to 50 
sheets at one time. 
Thus, it can be seen that current finishing techniques impose size, cost 
and power limits upon booklet making devices, and hinder the use of these 
devices in many applications. 
Therefore, there is an unresolved need for a finishing technique that 
permits one to make booklets using a low-power device which is inexpensive 
and compact. 
SUMMARY OF THE INVENTION 
A low cost, low power method and compact apparatus for finishing of printed 
sheets into booklets is described. Novel mechanical operations permit the 
manufacture of a very low-cost, off-line booklet maker for use with 
desktop laser and ink jet printers. The technology can scale to 
medium-speed, in-line booklet manufacture. The method is novel because 
most of the finishing operations are performed on a sheet-by-sheet basis 
using precision paper positioning and a transverse tool carrier that cuts, 
scores, folds, punches, and staples the sheets. To form a finished 
saddle-stitched booklet, each sheet is cut to length determined by its 
sequence in the booklet and paper thickness, scored, punched (if 
required), folded, accumulated in a stack, and stapled. The sheet-wise 
method allows finishing operations to be done with low-cost tools and low 
actuation forces. 
This invention eliminates the cost and bulk of finishing operations while 
allowing more operations to be done in a compact, low-cost machine. The 
use of sheet-wise operations reduces the power and bulk requirements of 
the finisher allowing operations to be controlled with low-cost DC 
servomotors and solenoids. The use of precision X-Y position control 
leverages pen-plotter and printer engineering expertise in sheet-wise 
paper handling. The booklet maker described herein concentrates finishing 
operations into a single module suitable for off-line and on-line 
processing.

DETAILED DESCRIPTION OF THE INVENTION 
Embodiments of the invention are discussed below with reference to FIGS. 
1-5. Those skilled in the art will readily appreciate that the detailed 
description given herein with respect to these figures is for explanatory 
purposes, however, because the invention extends beyond these limited 
embodiments. 
FIG. 1 is a diagram illustrating a printer 110 and binding finisher 120 
system suitable for use as a booklet maker 100 according to the present 
invention. There is a significant business opportunity for a low-cost 
booklet maker producing finished documents in the electronic publishing 
environment. The present invention incorporates novel electromechanical 
processes to reduce cost, size, and power requirements for finishing 
operations. This is accomplished with novel operations executed on a 
per-sheet basis using sensors and embedded intelligence, rather than bulk 
processes (e.g., cutting and trimming) typically performed on 10's to 
1000's of sheets at one time. This approach facilitates small, inexpensive 
and compact solutions suitable to the desktop and well-matched in 
performance and cost to office ink jet and laser printers. 
FIG. 2 illustrates process flow according to an embodiment of the present 
invention. For this embodiment, the process flow 200 begins with the 
feeding and alignment 210 of a printed sheet. The present invention breaks 
the paradigm for booklet making. Operations such as trimming 220, scoring 
230, folding 240, and hole-drilling (not shown) are performed on each 
sheet. Although trimming to length is shown in the diagram, trimming to 
width can also be done. In either event, the trimmed portions are ejected 
for disposal 250. The sheets are then assembled by stacking into a 
booklet, stapled 260, and delivered to an output tray. Fundamental 
differences distinguish this invention from previous finishing approaches. 
For example, consider a saddle-stitched booklet as shown in FIG. 3A. In 
typical finishing processes, sheets of equal dimension are assembled in a 
stack, stapled, folded, and finally trimmed to produce an even edge. 
Because outer sheets wrap around inner sheets, simply assembling the 
booklet and stapling produces a chamfered edge with the inner sheets 
sticking out and the outer sheets (and cover) appearing to be shorter. The 
enlargement of FIG. 3A illustrates the chamfered edge. Traditionally, the 
entire booklet is trimmed inboard of the edge of the cover (i.e., the 
shortest sheet because of the longest wrap length) to produce an even edge 
(shown in FIG. 3B). 
In the present invention, each sheet is precision-trimmed individually to a 
prescribed length depending on paper thickness and its position in the 
booklet: the innermost sheet is shortest and the outermost sheet, the 
cover, is the longest. Each sheet is similarly scored in a different 
position from one edge creating a fold line in the center of each sheet. 
Implementing such operations requires the ability to load, align, 
register, and position paper repeatably to about 0.001" between sheets. 
Hewlett-Packard Company ("HP") has developed this expertise over many 
years with gritwheel pen plotters and ink jet printers. When the sheets 
are assembled, registered on the fold line, and stapled together, a 
finished booklet is produced with an even edge. 
The invention incorporates additional novelty to reduce cost and add 
flexibility to the finishing operations: precision motion along the paper 
feed axis locates each sheet for an operation; trim, score, punch, and 
staple operations are performed by a toolset moved transverse to the sheet 
feed direction on a tool carrier. This unique approach minimizes the 
forces and power required to perform finishing operations and allows 
production of a lightweight, inexpensive mechanism employing small DC 
servomotors, stepping motors, and solenoids. 
DESCRIPTION OF THE INVENTION 
The following points describe several features of our invention: 
Finishing operations, except for final binding, are performed one sheet at 
a time. This is a primary element of novelty in this invention. 
Conventional booklet making operations, particularly trimming and 
punching, typically operate on the entire set of bound sheets. 
FIG. 4 illustrates an embodiment of a saddle-stitch binding finisher 120 
according to the present invention. Sheet 410 is fed into a station 420 
where a plurality of finishing operations (i.e., trim, score, punch, fold, 
and staple) are performed by a tool carrier 400 that moves transversely 
across the sheet (Y-direction) in a direction perpendicular to paper feed 
(X-direction). The position of the sheet 410 and the tool carrier 400 are 
precisely controlled and coordinated to accomplish the finishing 
operations. 
The tool carrier 400 individually or in combination carries a single sheet 
cutter 450, sheet-scoring tool (for folding) 430, punch (not shown), 
trim-waste grabber, and stapler 450 across the page to perform sheet-wise 
finishing operations. 
For one embodiment, the same Y-axis servo is used for multiple finishing 
operations to position individual tools or tools working in combination. 
Alternately, more than one Y-axis servo can be used. 
Operations performed sheet-wise minimize need for mechanisms subjected to 
high forces and with high power requirements. 
For one embodiment, these operations are to: 
CUT each sheet individually, 
SCORE each sheet individually, 
PUNCH each sheet individually, and 
partially FOLD each sheet individually. 
The score and/or fold operation on individual sheets provides a 
registration feature to align each sheet to the rest of the booklet. The 
use of the fold as a registration feature is an important aspect of the 
invention because conventional alignment based upon an edge will not work 
due to the differences in page length and fold position. 
A workpiece 460 shaped like an inverted or normal "V" collects sheets and 
aligns them for stapling. A friction or vibrating mechanism, or a push 
bar, assures alignment to a Y-axis stop. As shown in FIG. 4, the inverted 
"V" permits alignment to be accomplished using gravity by hanging the 
sheets across workpiece 460. On the other hand, an advantage of having a 
normal "V"-shaped workpiece is that the booklet can be assembled towards 
the inside from the outside cover. Thus, one need not know how many pages 
the booklet has prior to beginning the finishing process. For one 
embodiment, workpiece 460 can also be used as part of an ejection 
mechanism for delivering the completed booklet to an output tray. 
For one embodiment, alignment of each sheet involves: 
1. feeding the sheet into the mechanism; 
2. aligning the sheet to a Y-axis stop; and 
3. positioning the sheet in the X-axis with respect to a paper edge sensor 
and moving the sheet precisely with respect to this position in subsequent 
operations. 
The paper edge sensor can be an optoelectronic sensor of a type known in 
the art where the presence of media interrupts a reflected beam of light, 
and the signal can be processed into a precision measurement of sheet 
position. The paper edge sensor can also be used to read a barcode printed 
on a job ticket to provide instructions to the finisher. 
When assembled into a saddle-stitched booklet, each sheet has a different 
finished dimension (i.e., the page width in the assembled booklet) due to 
the effect of outer sheets wrapping over inner ones. In this invention, 
each sheet is trimmed to a unique and precise length and the fold line 
established so that the edge of the assembled booklet is flat as if all 
sheets had been trimmed together to final size. The trimming operation 
cuts only one edge of individual sheets to vary the page width--there is 
no need to cut both edges of sheet, and the entire book does not need to 
be trimmed to produce a flat edge after sheets are folded and stapled. 
This is a major element of uniqueness and novelty in this invention. The 
sheet width is determined by an algorithm and is a function of the page 
number and thickness of the paper. FIG. 5 illustrates an example of a trim 
schedule for media (approximately 0.00325 inch thick) according to an 
embodiment of the present invention. 
The number of sheets in the booklet and other job and media parameters can 
be specified electronically, through a network connection, a front panel, 
or by using a machine-readable job ticket. 
The number of pages in the booklet need not be specified in advance if the 
booklet is made with the cover as the first sheet and additional sheets 
follow the cover through the finishing operation. In this case, the trim 
schedule can be made a function of page count (and media thickness) until 
another cover sheet or job separator is encountered. 
Software adjusts the location of printed images on each sheet with respect 
to a fixed edge. The position will vary sheet-wise and depend on the page 
number in the booklet. For one embodiment, this is handled automatically 
in the printer driver when the booklet making option is selected. 
It is possible to measure individual sheet thickness sheet-by-sheet within 
the booklet and adjust the trim algorithm accordingly based on the 
accumulated number of sheets and their thickness. This allows for 
variation in page thickness within booklet, such as card stock for 
different chapters, etc. Thickness information on a sheet-by-sheet basis 
can be made by measurement as each sheet is processed. Alternatively, a 
sheet thickness specification may be included as data in an electronic or 
machine-readable job ticket. 
A plurality of staple forming tools (i.e., anvils) are arranged at multiple 
fixed positions along the fold line of sheets and a staple head moves 
across the stack into registration with these tools one at a time to 
staple the stacked and partially-folded sheets into a booklet. 
Multiple staple heads (and anvils) may be used to staple the stacked and 
partially-folded sheets into a booklet. 
The finishing tools (e.g., trimmer, punch, score and fold (470 of FIG. 4) 
tools, and stapler) may move with the tool carrier and be selected one or 
more at a time, or may be parked out of the paper path and clutched onto 
the carrier to perform their function. 
Cut and score tools may be left at either end of the tool carrier travel so 
as to avoid retracing tool path to put tool away. This increases 
throughput by eliminating extra tool movement. For example, the motion 
would be . . . 
Sheet 1: Cut (left to right)--Score (right to left) 
Sheet 2: Score (left to right)--Cut (right to left) 
Sheet 3: etc. 
A friction device attached to tool carrier accomplishes ejection of waste 
paper strips from the trim operation. Strips are moved off to the side and 
ejected into separate container by action of cut sheet being moved to fold 
position. Alternatively, cut strips may be discharged into a slot near the 
cutting tool using mechanical or vacuum assistance or a combination 
thereof. 
Saddle-stitched booklets frequently exhibit an effect called "pillowing," 
where the fold is indistinct and the booklet does not lie flat. Scoring 
and folding each sheet achieves a significant reduction of pillowing 
compared to folding of the bound stack after stapling. 
The many features and advantages of the invention are apparent from the 
written description and thus it is intended by the appended claims to 
cover all such features and advantages of the invention. Further, because 
numerous modifications and changes will readily occur to those skilled in 
the art, it is not desired to limit the invention to the exact 
construction and operation as illustrated and described. Hence, all 
suitable modifications and equivalents may be resorted to as falling 
within the scope of the invention.