Printing system with a function of printing on labels

A label separating system for separating labels from a backing web after the labels have been printed is disclosed. This system utilizes the paper holding roller which is used for holding paper against the platen as it is printed and a separating roller upstream from the paper holding roller. A tractor feed upstream of the separating roller draws the backing web from the platen over the separating roller. A holding member is positioned to limit movement of the paper holding roller as the backing web is placed under tension by the tractor feed, thereby insuring that the backing web disposed between the platen and the separating roller is urged toward a line connecting the center of the platen and the center of the separating roller. This insures that the backing web is bent to a sufficient degree as it passes over the separating roller to cause separation of the label. The holding member for holding the paper holding roller can be mounted on a pivoted lever that also serves as a part of a detachable mounting system for mounting the label separator on the printer. A guide roller is positioned adjacent and parallel to the separating roller and, with the separating roller, defines an S-shaped path for the backing web which further insures separation of the label from the backing web.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a printing system having a function of printing 
not only on ordinary sheets such as web sheet or cut sheets, but also on 
labels removably adhered to a backing web. 
2. Description of Related Art 
A typical printing system for printing on labels is disclosed, for example, 
in British unexamined patent publication No. 2,194,488A laid open of Mar. 
9, 1988. 
In such a printing system, a separating roller which bends and guides a 
backing wet contacting with a side on which labels are not adhered is 
arranged in a downstream side of a platen in a paper feeding direction, 
and a paper holding roller is arranged between the platen and the 
separating roller. 
The paper holding roller is biased toward the outer periphery of the platen 
and moves between a holding position contacting with the outer periphery 
of the platen and releasing position separating therefrom by a 
predetermined distance. 
The backing web with labels extends to a pull tractor through the platen, 
the paper holding roller, and the separating roller, and the labels 
adhered on the backing web are printed on the platen. The backing web with 
printed labels is fed in the feeding direction by the tractor. In this 
moment, the tension force in the feeding direction of the backing web acts 
on the backing web with the printed labels. The paper holding roller is 
moved in a direction away from the platen by the tension force resulting 
from the above feeding movement, against its normal bias in the direction 
of the platen. 
Further, the position of the paper holding roller is not fixed because the 
tension force which acts on the backing web changes according to the 
change of the feeding speed of the backing web. Specifically, the paper 
holding roller moves to a tangent common to the platen and the separating 
roller when the feeding speed of the backing web becomes fast and the 
tension which acts on the backing web becomes great. 
In the printing system of the construction described above, the label is 
not always separated from the backing web by the separating roller, and is 
fed with the backing web being curved along the separating roller. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to overcome the above 
problems and to provide a print system which can prevent a label from not 
separating from a backing web. 
The object is attained by providing a print system for printing not only on 
ordinary papers, such as web sheet or cut sheet, but also on labels 
removably adhered to a backing web on a same platen comprising: a 
separating roller which is arranged in the downstream side of a platen in 
a paper feeding direction, and which curves and guides a backing web with 
labels contacting with a side on which labels are not adhered, a paper 
holding roller which is arranged between the platen and the separating 
roller and is urged toward the outer periphery of the platen, and which 
moves between a holding position contacting with an outer periphery of the 
platen and a releasing position separated therefrom by a predetermined 
distance, and holding means for holding the paper holding roller in an 
operating position wherein the portion of the backing web with the labels 
which extends between the platen and the separating roller is curved in 
the direction of a line passing through the center of the platen and the 
center of the separating roller. 
In the print system thus constructed, when the label adhered on the backing 
web is printed on the platen and the backing web with printed label is 
fed, the paper holding roller is moved by the tension which acts on the 
backing web in the direction of the releasing position, separated from the 
platen by a predetermined distance. At this time, the paper holding roller 
is held in the operating position, which is located between the holding 
position and the releasing position, by the holding means. And, the 
backing web with the labels extending between the platen and the 
separating roller is pressed by the paper holding roller held in the 
operating position, and is curved in the direction of the line passing 
through the center of the platen and the center of the separating roller. 
When the backing web is pressed in the direction to the line passing 
through the center of the platen and the center of the separating roller 
and is turned along the outer periphery of the separating roller, the 
force for peeling the label from the backing web is strong because of the 
elastic force of the label. As a result, the label is peeled reliably from 
the backing web. 
As mentioned above, according to the present invention, it is possible to 
hold the paper holding roller by the holding means in the operating 
position, which is located between the holding position, contacting with 
the outer side of the platen, and the releasing position, separated from 
the platen by a predetermined distance. Therefore, the backing web with 
the labels extending between the platen and the separating roller is 
turned along the outer side of the separating roller, curving in the 
direction toward the line connecting the center of the platen and the 
center of the separating roller, by the paper holding roller. And the 
force for peeling the labels from the backing web becomes strong because 
of the elastic force of the label. As a result, the labels are peeled 
reliably from the backing web. The labels are prevented from curving with 
the backing web along the separating roller, without peeling from the 
backing web.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A detailed description of one preferred embodiment of a printer embodying 
the present invention will now be given referring to the accompanying 
drawings. As shown in FIG. 2, a printing system 1 includes a system body 2 
and a label separating unit 20 which is removably mounted on the system 
body 2. 
The system body 2 includes a platen 4 supported by a platen shaft 3, a 
print head 5, which is disposed in spaced, opposing relationship to the 
platen 4 to define a space for passage of a sheet between the platen 4 and 
which moves leftwardly and rightwardly along the platen 4, and a push 
tractor 6 for feeding print paper, such as a backing web 15, to the platen 
4. 
A roller arm 9 supporting on the upper portion thereof a roller shaft 8 
having a paper holding roller 7 is pivotably mounted for pivoting about an 
axis 10. 
The paper holding roller 7 of the roller arm 9 is arranged between the 
platen 4 and a separating roller to be described later. The paper holding 
roller 7 is rotated on the axis 10 between a holding position contacting 
with the outer periphery of the platen 4, as shown in FIG. 4, and a 
releasing position separated from the outer periphery of the platen 4 by a 
predetermined distance as shown in FIG. 5. The paper holding roller 7 is 
held in the holding position and the releasing position by a spring 
The spring 11 is provided between the roller shaft 8 supported on the upper 
portion of the roller arm 10 and a spring hook portion 12 formed on a 
predetermined position of the frame of the system body 2. 
The label separating unit 20 is mounted removably on the system body 2 and 
on the downstream side of the platen 4, in the paper feeding direction. As 
shown in FIG. 2 and FIG. 3, a drive shaft 22 and a guide shaft 23 are 
supported in parallel on a pair of left and right unit frames 21 of the 
label separating unit 20. A tractor drive gear 25 which is removably 
engaged with an operation gear (not shown) provided in the system body 2 
through an intermediate gear 24 is provided at one end of the drive shaft 
22 (at a left end portion in FIG. 3). A pair of tractors 27, which 
constitutes a pull tractor 26, are supported slidably on the drive shaft 
22 and the guide shaft 23 and are adjusted according to the width of the 
sheet being printed. Each tractor 27 includes a pair of tractor belts 30 
extending between drive pulleys 28 fitted on the drive shaft 22 and 
corresponding follower pulleys 29 disposed behind the drive pulleys 28. 
Engaging projections 31 are provided on the outer peripheries of the 
tractor belts 30 and are adapted to be engaged in the sprocket holes 17 of 
the backing web 15 to feed the backing web 15 when the tractor belts 30 
are turned by the drive pulleys 28. The drive pulley 28 is fitted on the 
drive shaft 22 to be rotated by the drive shaft 22 and is slidably along 
the drive shaft 22. 
A pair of brackets 32 are provided between the pair of left and right unit 
frames 21. A separating roller 33 and a guide roller 34 are supported on 
the brackets 32, between the platen 4 and the tractor 26. Rollers 33 and 
34 extend in parallel to the platen 4. 
Subsequently, description is given of a structure in which the label 
separating unit 20 is removably supported on the system body 2. At the 
lower portion of each unit frame 21 thus constructed, as shown in FIG. 2, 
a semicircular fitting recess 21a, which is removably engaged with the 
outer periphery of platen shaft 3 and a engaging portion 21b, which is 
engaged with a engaging pin 3 installed on a frame of the system body 2 
(not shown), are formed. 
Each of the unit frames 21 has engaging levers 35 mounted for pivotal 
motion on an inner side thereof by means of pins 36. Each engaging lever 
35 has a knob portion 35b formed at an upper portion thereof while a hook 
portion 35a is formed in a rearward direction at a lower end of the 
engaging lever 35. The engaging levers 35 are disposed such that the hook 
portions 35a thereof may be engaged with engaging pins 13 provided on the 
opposite side portions of the system body 2. 
Each engaging lever 35 is urged in a position that the hook portion 35a is 
engaged with the engaging pin 13 by a tension spring 37. The fitting 
recesses 21a of two unit frames 21 are fitted onto the platen shaft 3 and 
the hook portions 35a of the engaging levers 35 and the engaging portions 
21b of the unit frames 21 are engaged with the engaging pins 13, so that 
the label separating unit 20 is installed on the system body 2. The 
engaging levers 35 are pivoted by the knob portions 35b against the urging 
force of the tension springs 37 and the hook portions 35a of the engaging 
levers 35 are removed from the engaging pins 13, so that the label 
separating unit 20 can be removed from the system body 2. 
As shown in FIG. 1 and FIG. 2, each engaging lever 35 has a holding portion 
38 formed at an upper end thereof and at a position spaced from the roller 
shaft 8 of the paper holding roller 7, when the roller 7 is engaging the 
periphery of the platen. The engaging levers 35 are disposed such that the 
holding portion 38 thereof may be engaged with the roller shaft 8 and may 
hold the paper holding roller 7 in the operating position. 
As shown in FIG. 2, when the label 16 adhered on the backing web 15 is 
printed by the print head 5 on the platen 4 and the backing web 15 with 
printed label 16 is pulled by the pull tractor, the paper holding roller 7 
is moved in a direction away from the platen 4 by the tension force which 
acts on the backing web 15. At this time, the holding portion 38 engages 
with the roller shaft 8 so that the paper holding roller 7 is prevented 
from moving further away from the platen 4 and is held in the operating 
position. The part of the backing web 15 extending between the platen 4 
and the separating roller 33 is pressed by the paper holding roller 7, 
which is in the operating position, and the web 15 is curved by a 
predetermined distance in the direction of a line L which passes through 
the center of the platen 4 and the center of the separating roller 33. 
Usually, many labels 16 are removably adhered on the backing web 15 in a 
longitudinal direction of the label adhering side in a fixed pitch. The 
sprocket holes 17 are arranged corresponding to the engaging projections 
31 of the tractor belt 30 of the tractor 27 on both edges of the backing 
web 15. 
Next, operation of the printing system of the above-described embodiment 
will be explained. 
In order to print on the labels 16 adhered on the backing web 15, the 
backing web 15 is extended from the push tractor 6 to the pull tractor 26 
over the platen 4, the separating roller 33, and the guide roller 34. At 
this time, the paper holding roller 7 is arranged in the releasing 
position as shown in FIG. 5. 
After the backing web 15 with labels 16 is set, the paper holding roller 7 
is moved from the releasing position to the holding position, passing the 
holding portion 38 of an engaging lever 35. At this time, the paper 
holding roller 7 is urged by the spring 11 to the holding position, so 
that the paper holding roller 7 presses the label-carrying side of the 
backing web 15, and the backing web 15 is curved in the direction of the 
center line L. 
In this condition, when the label 16 adhered on the backing web 15 is 
printed by the print head 5 on the platen 4, the push tractor 6 and the 
pull tractor 26 are driven in synchronization with the rotation of the 
platen 4, and the backing web 15 moves in the feeding direction a 
predetermined distance. At this time, the paper holding roller 7 is moved 
in the direction of the releasing position against the urging force of the 
spring 11 by the tension force which acts on the backing web 15. 
However, the roller shaft 8 of the paper holding roller 7 is engaged by the 
holding portion 38 of the engaging lever 35 and the movement of the roller 
shaft 8 is restricted, so that the paper holding roller 7 is held in the 
operating position. As a result, the part of the backing web 15 extending 
between the platen 4 and the separating roller 33 is pressed by the paper 
holding roller 7, which is in the operating position, and, as shown in 
FIG. 2, the part of the backing web 15 between platen 4 and separating 
roller 33 is curved in the direction of the center line L by a 
predetermined distance. 
On the other hand, the part of the backing web 15 extended from the 
separating roller 33 to the guide roller 34 is curved along the outer 
peripheries of each roller and is fed by the pull tractor 26. 
Therefore, as shown in FIG. 1 and FIG. 2, the label 16 adhered on the 
label-carrying side of the backing web 15 is peeled reliably from the 
backing web 15 by the separating roller 33. 
In other words, the paper holding roller 7 is held in the operating 
position by the holding portion 38 of the engaging lever 35. The part of 
the backing web 15 extending between the platen 4 and the separating 
roller 33 is curved in the direction of the center line L by the paper 
holding roller 7, and is turned in a zigzag fashion along the outer 
peripheries of the separating roller 33 and guide roller 34. Therefore, 
the force for peeling the label 16 from the backing web 15 is developed 
from the elastic force of the label 16. As a result, the label 16 is 
peeled reliably from the backing web 15. This prevents the label 16 from 
feeding with the backing web 15 along the outer periphery of the 
separating roller 33 without peeling from the backing web 15. 
Although the holding portion 38 for holding the paper holding roller 7 in 
the operating position was formed at the upper end of the engaging levers 
35 in the above-mentioned embodiment, it is possible for the holding 
portion constituting the hold means to be separate from the engaging 
levers 35. 
In the description of the preferred embodiment, the various web-engaging 
members for separating the label from the web have been described as 
rollers, for example, paper holding roller 7, separating roller 33, and 
guide roller 34. However, it should be realized that for purposes of the 
invention, one or more of these elements may be non-rotating members that 
have smooth web-engaging surfaces for allowing the web and adhered labels 
to be drawn over such surfaces, thereby effecting the desired label 
separation.