Perfecting printer with turnover unit

A perfecting printer comprises a feeding roller for successively feeding cutforms accommodated in a feed stacker onto a transfer path provided with pairs of reversible transfer rollers. Each cutform is first transferred forward past a printing unit without printing. The cutform is then transferred rearward and printed on its front face. The one-face printed cutform is then guided into a return path which joins the transfer path at a position before the printing unit. Upon passage through the return path, the cutform is turned over and returned to the stacker by a turnover unit disposed above the stacker. Finally, the turned over cutform is transferred forward and printed on its rear face again by the same printing unit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a perfecting printer for separately printing both 
faces of individual cutforms by a single printing unit. 
2. Description of the Prior Art 
Perfect or two-face printing is advantageous in that it halves the total 
number of sheets or cutforms required to print out a given amount of 
information by one-face printing. Because of such an advantage, various 
attempts have been made to provide perfecting printers. 
In one possible example, a perfecting printer employs two separate printing 
units respectively for printing the front and rear faces of each cutform 
during a single forward transfer thereof. 
Another example of perfecting printer incorporates a single printing unit 
through which each cutform is passed twice, first with its front face 
directed to the printer head and next with its rear face directed thereto. 
A more specific arrangement of such an example is disclosed in Japanese 
Patent Application Laid-open No. 59-115875 (Laid-open: July 4, 1984; 
Filed: Dec. 23, 1982; Application No.: 57-224852; Inventor: Yutaka 
OGINOTANI) or in Japanese Patent Application Laid-open No. 60-257254 
(Laid-open: Dec. 19, 1985: Filed: June 4, 1984: Application No.: 
59-114045; Inventor: Osamu SAKAI et al) and for clarity will now be 
described with reference to FIG. 9 of the accompanying drawings. 
Referring to FIG. 9, a prior art perfecting printer comprises a feed 
stacker 100 receiving a stack of cutforms or sheets 101, and a feeding 
roller 102 disposed above the stacker 100 for successively feeding the 
cutforms 101 onto a transfer path 103. A printing unit 104 is arranged at 
an intermediate position of the transfer path 103. Behind the printing 
unit 104 is a pivotal shift plate 105 for selectively directing the 
cutform 101 into a return-turnover path 106 or into a discharge stacker 
107. The return-turnover path 106 extends substantially around the 
printing unit 104 and is provided with pairs of return rollers 108. 
Adjacent to the outlet end of the return-turnover path 106 is a re-feeding 
device 109 which is selectively pivotable to a first position for 
continuity with the return-turnover path 106 or to a second position for 
continuity with a guide plate 110 located immediately before the feeding 
roller 102. 
In operation, each cutform 101 fed onto the transfer path 103 with its top 
edge t directed forward is advanced by a pair of transfer rollers 111. 
During such advance, the front face of the cutform 101 is printed from the 
top edge t by the printing unit 104, as illustrated in FIG. 10a. At this 
time, the shift plate 105 is pivoted to its lower position indicated in 
solid lines in FIG. 9. Thus, the cutform 101 is directed into the 
return-turnover path 106 after front-face printing. 
Since the return path 106 extends substantially around the printing unit 
104, the cutform 101 is completely turned over after it has been moved 
through the path 106 by the return rollers 108. The cutform 101 thus 
turned over is received in the re-feeding device 109 pivoted to the first 
position. The re-feeding device 109 is then pivoted to the second position 
indicated in broken lines in FIG. 9 to re-feed the cutform 101 onto the 
transfer path 103 by way of the guide plate 110. 
The cutform 101 now with its bottom edge b directed forward is advanced 
along the transfer path 103. During this second forward transfer, the rear 
face of the cutform is printed from its bottom edge b, as shown in FIG. 
10b. 
Finally, the shift plate 105 is pivotally raised, and the cutform 101 is 
taken out into the discharge stacker 107. 
Though capable of printing both faces of each cutform 101 by the single 
printing unit 104, the prior art printer has the following disadvantages. 
According to the prior art arrangement, since the cutform 101 is 
transferred only in the forward direction on the transfer path 103, the 
inlet end of the return-turnover path 106 must be positioned behind the 
printing unit 104 in order to receive the cutform 101 after printing. 
Therefore, the return path 106 must extends substantially around or over 
the printing unit 104 to bring the cutform 101 back to the feed side of 
the printing unit 104. Such an arrangement inevitably results in a 
considerable increase in the overall size of the printer, thereby 
providing difficulty in manufacture and handling. 
Further, with the prior art printer, printing on the front face of the 
cutform 101 is started from the top edge t, whereas printing on the rear 
face thereof is initiated from the bottom edge b. Such a printing manner 
requires complicated control of the printing unit 104 in order to provide 
identical margins (side margins as well as top and bottom margins) with 
respect to both faces of the rectangular cutform 101. Particularly, when 
the cutform 101 carries ruled frames 112, 112' (see FIGS. 10a and 10b) or 
lines (not shown) at corresponding positions on both faces thereof, 
variations or deviations in printing positions due to poor control of the 
printing unit 104 become unacceptable. In addition, a similar problem also 
occurs due to an unexpected slide in the movement of the cutform 101 
during printing. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to provide a 
perfecting printer which, while employing a single printing unit for cost 
reduction, is extremely compact and simple in construction, and which is 
substantially free of printing deviations with respect to both faces of 
each cutform. 
Another object of the invention is to provide a perfecting printer which 
incorporates a novel turnover unit. 
According to the invention, there is provided a perfecting printer 
comprising accommodating means for receiving a stack of cutforms, a 
transfer path extending from the accommodating means, feeding means for 
successively feeding the cutforms onto the transfer path, transfer means 
for reversibly transferring each cutform along the transfer path; printing 
means for separately printing both faces of the cutform, a return path 
joining the transfer path at a position before the printing means for 
allowing return movement therethrough of the cutform when the transfer 
means is reversed, and turnover means disposed above the accommodating 
means and adjacent to an outlet of the return path for turning over the 
cutform received from the return path and for returning it again into the 
accommodating means. 
Other objects, features and advantages of the invention will be readily 
understood from the following detailed description given with reference to 
the accompanying drawings. However, it should be understood that the 
detailed description and specific examples, while indicating preferred 
embodiments of the invention, are given by way of illustration only, since 
various changes and modifications within the spirit and scope of the 
invention will become apparent to those skilled in the art from this 
detailed description.

DETAILED DESCRIPTION 
Referring now to FIG. 1 of the accompanying drawings, a perfecting or 
duplex printer according to the invention includes a printer housing 1 to 
the rear of which is mounted a feed stacker 2 accommodating a stack of 
separate sheets or cutforms 3. The feed stacker 2 is accessible from 
outside to receive another supply of cutforms when needed. 
According to the illustrated example, the feed stacker 2 is supported at 
its front end by a movable carrier 4. A rack 5 fixed to the carrier 4 is 
in mesh with a pinion 6 which is connected through a train of gears 7 to a 
pulse motor (stepping motor) 8. Thus, when the motor 7 is selectively 
rotated in a forward or reverse direction, the stacker 3 is 
translationally moved up or down, as indicated by a double-headed arrow A. 
A feed roller 9 made of rubber for example is disposed immediately above 
the feed stacker 2 to feed one sheet 3 at a time onto a transfer path. 
According to the illustrated example, the transfer path is provided by a 
guide member 10 which may consist of plural guide plates or of a single 
plate. 
Three opposed pairs of transfer rollers 11, 12, 13 are arranged along the 
transfer path 10, so that each cutform 3 passes between each pair of 
rollers during transfer. These rollers are drivingly rotatable in both 
forward and reverse directions for the purpose to be described 
hereinafter. 
Between the two front pairs of transfer rollers 12, 13 in the transfer path 
10 is arranged a printing unit 14 which comprises a printer head 14a, such 
as a dot printer head, and a platen 14b positioned immediately below the 
head 14a in opposed relation thereto. 
Immediately before and beyond the printing unit 14 are respectively 
arranged a pair of sensors 15, 16 which detect the forward and rearward 
edges of each cutform 3 to generate operational signals for the printer 
head 14a. 
According to the invention, a return path 17 meets the transfer path 10 at 
a position immediately before the rearmost pair of transfer rollers 11. 
More specifically, the return path 17 is defined by slightly spaced inner 
and outer return guide members 18, 19 each of which may be constituted by 
plural plates or by a single plate. Each return guide member has a lower 
portion 18a, 19a which is gently curved to provide a smooth continuity of 
the return path 17 with the transfer path 10 when viewed in the return 
direction. 
Preferably, the lower edge 18b of the inner guide member 18 is slightly 
bent downward to widen the inlet end of the return path 10. The purpose of 
this arrangement will be explained hereinafter. 
The return path 17 is provided at an intermediate position thereof with a 
pair of return rollers 20 which are drivingly rotated only in one 
direction, i.e., in the return direction. If required, an additional pair 
or pairs of return rollers may be provided. 
The return path 17 extends to a location above the feed stacker 3 where a 
turnover unit 21 is arranged. 
As illustrated in FIGS. 2 to 5, the turnover unit 21 includes a turnover 
roller 22 supported on a main shaft 23 which in turn is rotatably 
supported by a pair of side walls 1a of the housing 1 (see FIG. 3). A 
drive roller 4a and a free roller 24b are mounted respectively on a drive 
shaft 25a and a free shaft 25b, both shafts being also rotatably supported 
by the housing side walls 1a. An endless belt 26 is wound round the drive 
and free rollers 24a, 24b, and held in driving contact with the turnover 
roller 22. 
One end of the drive shaft 25a is connected to a pulse motor (stepping 
motor) 27 by means of a transmission 28, as illustrated in FIG. 3. Thus, 
when the motor 27 is operated, the turnover roller 22 is rotated to pull 
in the cutform 3 exiting from the return path 17. 
The turnover unit 21 further includes a pair of trap disks 29 mounted on 
the main shaft 23 on both sides of the turnover roller 22. Each disk 29 is 
substantially equal in diameter to the trap roller 22 and carries a pin 30 
by which is pivotally supported a trap lever 31 formed at one end with a 
pawl 31a. The other end of the lever 31 is connected to one end of a weak 
spring 32 having its other end fixed to a suitable portion of the disk 29. 
The spring 32 causes the lever 31 to pivotally come into abutment with a 
stopper pin 33 which is fixed at another suitable portion of the disk 29. 
In this position, the pawl 31a of the lever 31 is located outside the 
circumference of the disk 29. However, when the lever 31 is pivoted 
against the spring 32, the pawl 31 can come inside the disk circumference. 
A pair of sheet stoppers 34 extend laterally inward from the housing side 
walls 1a toward the circumference of the respective disks 29. However, the 
inner ends of the respective stoppers 34 do not interfere with the 
corresponding trap levers 31 which rotate with the disks. The distance 
between the respective inner ends of the stoppers 34 is smaller than the 
width of the sheet 3 (see FIG. 3), so that the forward edge of the sheet 
can come into abutment with the stoppers 34. 
Entry of the sheet 3 into the turnover unit 21 is detected by a sensor 35 
disposed over the axis of the turnover roller 22 to start the pulse motor 
27. 
One end of the main shaft 23 is provided with a positioning disk 36 having 
a marking slit (not shown). Arranged in cooperative relation to the 
positioning disk 36 is a photoelectric sensor 37 having a light emitting 
element (not shown) and a light receiving element (not shown). Normally, 
the light path of the photoelectric sensor 37 (between the light emitting 
element and the light receiving element) is interrupted by the positioning 
disk 36. However, when the marking slit of the disk 36 happens to come in 
alignment with the light path, the sensor 37 is activated to generate a 
signal. The position of the marking slit is determined so that such signal 
generation occurs when each trap disk 22 or the trap lever 31 rotating 
therewith assumes the initial position illustrated in FIGS. 1 to 4. 
The perfecting printer described above operates in the following manner. 
Referring to FIG. 1, a stack of cutforms 3 is first placed in the feed 
stacker 2 with the top edge T of each cutform directed reward. Then, the 
stacker 2 is translationally moved upward by the pulse motor 7 until an 
uppermost or first cutform 3 comes into contact with the feed roller 9, 
whereby the cutform 3 is fed onto the transfer path 10, as indicated by an 
arrow B. After complete feeding of the first cutform 3, the stacker 2 is 
immediately lowered to suspend subsequent feeding. 
The cutform 3 thus fed in is then moved forward along the transfer path 10 
by the forwardly rotating transfer rollers 11-13 to a position C beyond 
the printing unit 14. During this forward transfer, no printing is 
conducted by the printing unit 14. 
The position C of the cutform 3 is detected by its top edge T passing over 
the sensor 16. Upon such detection, the transfer rollers 11-13 are 
reversed in rotation to move the cutform 3 backward. During this backward 
movement, the printing unit 14 effects printing on the front face of the 
cutform 3 starting from the top edge T, as clearly illustrated in FIG. 5. 
After printing the front face, the cutform 3 reaches the rearmost pair of 
rollers 11 and passes therethrough. When passing between the rollers 11, 
the top edge T of the cutform 3 must be raised slightly from the surface 
of the guide member 10 due to the lower one of the roller pair 11 
projecting above the guide member 10. The inlet end of the return path 17 
is positioned immediately before the rollers 11. Thus, the raised top edge 
T of the cutform 3 is brought to the inlet end of the return path 17 
before bowing down and successfully introduced thereinto. Further, the 
downwardly bent lower edge 18b of the inner guide member 18 serves to 
guide the cutform 3 into the return path 17. 
Thus, the rearmost pair of rollers 11 provide a path shifting function in 
addition to a sheet transferring function. If required, the path shifting 
rollers 11 may be arranged so that an imaginary line connecting between 
their respective axes is at an angle to a plane normal to the transfer 
path 10. Such arrangement ensures that the top edge T of the cutform 3 is 
directed slightly upward upon passage between these rollers 11 to prevent 
any failure in entering the return path 17. 
The cutform 3 thus guided into the return path 17 is then transferred to 
the turnover unit 21 by the return rollers 20. 
When the cutform 3 reaches the turnover unit 21, the top edge T of the 
cutform 3 is inserted between the turnover roller 22 and the endless belt 
26 as well as between each disk 29 and its associated pawl 31a, as 
illustrated in FIG. 4. This condition is detected by the sensor 35 which 
then generates a signal to start the pulse motor 27 (FIG. 3), thereby 
moving the belt 26 to rotate the turnover roller 22 and the trap disk 29. 
With the top edge T of the cutform 3 inserted or trapped between the trap 
disk 29 and the lever pawl 31a, the cutform 3 is forcibly pulled round the 
turnover roller 22 and the trap disk 29 by the rotation thereof, as 
illustrated in FIG. 6a. In other words, the top edge T of the cutform 3 is 
moved without being influenced by the gravity at the initial stage of 
rotation. 
On the other hand, when the top edge T of the cutform 3 comes into abutment 
with the sheet stoppers 34, its further advance is restrained while the 
trap lever 31 or the pawl 31a thereof continues to rotate with the disk 
29. As a result, the cutform 3 is released from the lever pawl 31a and 
gravitationally falls down onto the remaining stack of cutforms within the 
feed stacker 2, as shown in FIG. 6b. At this time, the top edge T of the 
cutform 3 comes into abutment with a front wall 1a of the stacker. 
Upon further rotation of the turnover roller 22, the cutform 3 is 
continuously paid out into the stacker 2 while being flexed, as 
illustrated in FIG. 6c. The cutform 3 is completely turned over when it 
has passed between the roller 22 and the belt 26. The cutform 3 thus 
turned over has its top edge T directed forward. 
In case the trap disk 29 (together with the turnover roller 22) makes more 
than a single complete turn before completely paying out the cutform 3, 
the lever 31 comes in contact with the underside of the cutform 3. 
However, the spring 32 having a very small biasing force allows the lever 
31 to be pressed downward, so that the lever 31 does not damage the 
cutform 3 nor hinder subsequent paying out thereof. 
After complete turnover of the cutform, the trap disk 29 together with its 
lever 31 is brought to their initial position illustrated in FIGS. 1 to 4. 
Such initialization is conducted by the combination of the positioning 
disk 36 and the photoelectric sensor 37 which acts to stop the pulse motor 
27, as described hereinbefore. 
With the cutform 3 thus turned over, the feed stacker 2 is again raised to 
bring that particular cutform into contact with the feed roller 9 (FIG. 
1). As a result, the cutform is transferred along the transfer path 10 by 
the forwardly rotating rollers 11-13. 
Upon reaching the printing unit 14, the top edge T of the cutform 3 is 
detected by the sensor 15 which actuates the printer head 14a to conduct 
printing on the reverse face of the cutform while it is moved forward, as 
illustrated in FIG. 7. In this way, the reverse face printing is also 
conducted starting from the top edge T of the cutform, so that there 
occurs no deviation in printing on both faces of the cutform. 
After completion of two-face printing, the cutform 3 is further transferred 
forward for discharge, as indicated by an arrow E in FIG. 1. The cutform 
may be received in a discharge stacker (not shown) in a known manner. 
The above procedure is repeated to conduct printing of the cutforms 
remaining in the feed stacker 2. 
As appreciated by comparing FIGS. 5 and 7, the printing unit 14 is adapted 
to print various characters and numerals selectively in opposite 
orientations because the transfer direction of the cutform 3 during 
printing of the sheet front face differs from that during printing of the 
sheet rear face. Such control of the printing unit 14 is known to those 
skilled in the art and will not be described here. 
According to the invention, the return path 17 joins the normal transfer 
path 10 at a position before the printing unit 14, and a part of the 
normal transfer path 10 is utilized as an extension of the return path 17 
when the transfer rollers 11-13 are reversely rotated. This arrangement 
obviates a conventional return path which extends all the way around a 
printing unit, thereby drastically reducing the overall space and weight 
of the printer. For this reason, the printer according to the invention is 
easy to manufacture and handle, and provides a space saving arrangement. 
Further, according to the invention, printing on both faces of each cutform 
is started from the top (same) edge thereof, so that there is no deviation 
in two-face printing. It should be appreciated that such a possibility is 
obtained by the reversibility of the transfer rollers 11-13. 
According to the embodiment illustrated in FIGS. 1 to 7, the return path 17 
joins the normal transfer path 10 at a position immediately before the 
rear most pair of transfers 11. However, the return path 17 may join the 
normal transfer path 10 at a position immediately before the intermediate 
pair of transfer rollers 12. In this case, the rear most pair of transfer 
rollers 11 need only to rotate in a forward direction, or may be dispensed 
with if the distance from the feed roller 9 to the intermediate pair of 
rollers 12 is short. 
The return path 17 may be modified in configuration and dimensions, 
provided that it joins the normal transfer path 10 at a position before 
the printing unit 14 and extends to the turnover unit 21 which is located 
above the feed stacker 2. 
The turnover unit 21 may also be modified. FIG. 8 shows one example of such 
modification. 
Referring to FIG. 8, a modified turnover unit 21' comprises a turnover 
roller 40 which is partially surrounded by a substantially arcuate guide 
41 arranged as slightly spaced from the roller 40. Each cutform 3 coming 
out from the 
return path 17 (see FIG. 1) is turned over when it has completely passed 
through a gap between the roller and the guide 41. 
As opposed to the turnover unit 21 of the foregoing embodiment in which 
each cutform 3 is pinched between the two moving parts 22, 26 for forcible 
advance, the modified turnover unit 21' utilizes a single moving part 40, 
so that it is necessary for the cutform 3 not to come into abutment with 
any object before the entire length L of the cutform 3 has passed through 
the gap between the roller 40 and the guide 41. 
The perfecting printer according to the present invention can be used in 
various applications which require printing. For example, the inventive 
printer can be used in combination with computers or word processors. 
The invention being thus described, it is obvious that the same may be 
modified in other various ways. For instance, the feed roller 9 may be 
replaced by a known vacuum-type feeder which comprises a holder for 
sucking up each of cutforms by vacuum and which is widely used in 
photocopiers. Further, the printing unit 14 may utilize various types of 
printer head. Such variations are not to be regarded as a departure from 
the spirit and scope of the invention, and all such modifications as would 
be obvious to those skilled in the art are intended to be included within 
the following claims.