Roll-up prevention device and label tip setting method for linerless label in thermal printer

In a roll-up prevention unit, an upstream roll-up prevention member guides a linerless label toward a platen roller. A downstream roll-up prevention member guides the linerless label away from the platen roller. Brackets have a roller engagement hole engaging with a roller shaft of the platen roller, and fixes the position of the roll-up prevention unit relative to the platen roller.

TECHNICAL FIELD

The present invention relates to a roll-up prevention device and a label tip setting method for a linerless label in a thermal printer, and in particular to a roll-up prevention device and a label tip setting method for a linerless label in a thermal printer that can prevent the linerless label from being rolled up during the feeding of the linerless label in both forward and reverse directions.

BACKGROUND ART

Conventionally, linerless labels, which are belt-like label paper sheets, are used for the purpose of saving resources. A linerless label does not use a liner sheet (release liner) that is temporarily attached to an adhesive layer on the back surface side of a label base. Printers for such linerless labels (e.g., thermal printers) have also been developed. JP 3636476B discloses a printer for linerless labels.

FIG. 7is a schematic side view of a thermal printer1as a comparative example. The thermal printer1includes a supply unit3for supplying a linerless label2, a detection unit4, a printing unit5, and a cutting unit6.

As apparent from an enlarged cross-sectional view of the linerless label2presented inFIG. 7, the linerless label2includes a belt-like label base7, an adhesive layer8that is formed on a back surface of the label base7, and a thermo-sensitive coloring agent layer9and a release agent layer10that are formed as a lower layer and an upper layer, respectively, on a front surface of the label base7.

Therefore, when the linerless label2is set in a rolled state in the supply unit3, the adhesive layer8and the release agent layer10are in contact with each other, and thus the linerless label2in the rolled state can be advanced in the form of a belt along a feeding path11, from the upstream side toward the downstream side, without adhesion between the inner layer and the outer layer of the linerless label2in the rolled state. Guide rollers12,13provided along the feeding path11can guide the linerless label2.

Note that position detection marks (not shown) are printed in advance on the back surface of the label base7at a predetermined pitch.

The detection unit4includes a mark sensor14, and detects the aforementioned position detection marks on the linerless label2. In this way, the position of the linerless label2relative to the printing unit5and the cutting unit6can be detected.

The printing unit5includes a thermal head15and a platen roller16, supplies and arranges the linerless label2to be nipped between the thermal head15and the platen roller16, feeds the linerless label2through the rotation and driving of the platen roller16, and supplies a heating element15A of the thermal head15with printing data. In this way, predetermined printing can be performed on the front surface of the label base7.

The cutting unit6includes a movable blade17and a fixed blade18, and issues individual linerless label strips2A by cutting off the linerless label2at a predetermined pitch. After the cutting unit6cuts off the linerless label2, the linerless label2is fed in reverse to be on standby for the next printing. Specifically, a label tip portion2B stands by while projecting toward the cutting unit6from the position of nip between the thermal head15and the platen roller16.

Note that the linerless label2may be perforated (not shown) at a predetermined pitch. In this way, individual linerless label strips2A can be issued by tearing off the printed linerless label2at the perforations without using any cutter.

In the thermal printer1configured in the above-described manner, components that come into contact with the adhesive layer8representing a back surface of the linerless label2, such as components provided along the feeding path11(the guide roller13, and if necessary, the guide roller12) and the platen roller16, are made of materials with releasing properties so as to secure their non-adhesive properties, or have been subjected to surface treatment so that their surfaces have releasing properties (non-adhesive properties). For example, the platen roller16is made of silicone rubber.

SUMMARY OF INVENTION

However, with continuous or long-term use of the thermal printer1, non-adhesive properties of the platen roller16gradually decrease. As a result, the linerless label2easily sticks to and is easily rolled up by the platen roller16.

Further, the linerless label2sticks to the platen roller16also when the operation of the thermal printer1has been stopped for a long period of time with the linerless label2nipped between the thermal head15and the platen roller16.

FIG. 8is an enlarged side view showing the state where the linerless label2has been rolled up by the platen roller16that has been moved in a forward direction, i.e., from the upstream side to the downstream side (forward feeding). As shown inFIG. 8, if the label tip portion2B of the printed linerless label2has been rolled up as a result of sticking to the outer circumferential surface side of the platen roller16(an outer surface of the platen roller16at the downstream side) along with the forward rotation of the platen roller16, there will be problems in the issuance and discharge of the linerless label2.

It takes great effort to remove the linerless label2that has stuck to the platen roller16. Even if the platen roller16is rotated in reverse, the linerless label2often remains stuck to the outer surface of the platen roller16at the upstream side.

FIG. 9is an enlarged side view showing the state where the linerless label2has been rolled up by the platen roller16that has been moved in a reverse direction (this means reverse feeding from the downstream side to the upstream side, and is also referred to as backward feeding). After a printed leading end (not shown) of the linerless label is cut off by the cutting unit6, the platen roller16is rotated in reverse so as to feed the subsequent linerless label2in reverse to a printing start position in the printing unit5and set the label tip portion2B at the printing start position in the printing unit5. As the supply unit3is not connected to a driving source and does not have the function of rewinding the linerless label2, the linerless label2becomes slack in a section that is upstream relative to the platen roller16. In a normal state, as indicated by a virtual line inFIG. 9, the slack linerless label2forms a gentle curve in a section that is upstream relative to the guide roller13. On the other hand, when the adhesive layer8of the linerless label2has stuck to the platen roller16, the platen roller16is rotated in reverse with the linerless label2stuck thereto, and the linerless label2is rolled up while being stuck to an outer circumferential surface of the platen roller16at the upstream side as indicated by a solid line inFIG. 9. This could possibly cause problems in the next printing and issuance. This phenomenon is notable when a backward feeding length is large.

When the linerless label2is perforated (not shown) at a predetermined pitch as mentioned earlier, the stress induced by the slack is concentrated on perforated portions, which have low stiffness. This could possibly cause bending and significant meandering of the linerless label2, and further facilitate the roll-up.

A mechanism has been devised that prevents the platen roller16from rolling up the linerless label2by providing a release member (roll-up prevention member) in the vicinity of the platen roller16. However, this requires precise designing of the short distance between the release member and the platen roller16, as well as stable maintenance of the relative positional relationship with the platen roller16in long-term use of the thermal printer1.

The present invention has been made in view of the above issues, and aims to provide a roll-up prevention device and a label tip setting method for a linerless label in a thermal printer that can prevent the linerless label from being rolled up during the feeding of the linerless label in both forward and reverse directions.

The focus of the following aspects of the present invention is to provide a roll-up prevention unit that can be integrated with a platen roller.

According to a first aspect, provided is a roll-up prevention device for a linerless label in a thermal printer configured to arrange the linerless label to be nipped between a thermal head and a platen roller, feed the linerless label from an upstream side toward a downstream side along a feeding path for the linerless label, and perform printing on the linerless label. The linerless label has a label base, an adhesive layer formed on a back surface of the label base, and a thermo-sensitive coloring agent layer and a release agent layer both formed on a front surface of the label base. The roll-up prevention device includes a roll-up prevention unit including a pair of left and right brackets, an upstream roll-up prevention member, and a downstream roll-up prevention member. The pair of left and right brackets is positioned at both left and right end sides of the platen roller, and the upstream roll-up prevention member and the downstream roll-up prevention member span between the brackets. The upstream roll-up prevention member is positioned upstream relative to the platen roller, and guides the linerless label toward the thermal head and the platen roller while being in contact with the adhesive layer representing a back surface of the linerless label. The downstream roll-up prevention member is positioned downstream relative to the platen roller, and guides the linerless label away from the platen roller while being in contact with the adhesive layer representing the back surface of the linerless label. At least one of the pair of left and right brackets has a roller engagement hole engaging with a roller shaft of the platen roller. At least one of the pair of left and right brackets fixes a position of the roll-up prevention unit relative to the platen roller.

According to a second aspect, provided is a label tip setting method for a linerless label in a thermal printer configured to arrange the linerless label to be nipped between a thermal head and a platen roller, feed the linerless label from an upstream side toward a downstream side along a feeding path for the linerless label, and perform printing on the linerless label. The linerless label has a label base, an adhesive layer formed on a back surface of the label base, and a thermo-sensitive coloring agent layer and a release agent layer both formed on a front surface of the label base. The platen roller is provided with a roll-up prevention unit including: a pair of left and right brackets; an upstream roll-up prevention member; and a downstream roll-up prevention member. The pair of left and right brackets is positioned at both left and right end sides of the platen roller, and at least one of the pair of left and right brackets has a roller engagement hole engaging with a roller shaft of the platen roller. The upstream roll-up prevention member and the downstream roll-up prevention member span between the pair of left and right brackets, the upstream roll-up prevention member is positioned upstream relative to the platen roller and guides the linerless label toward the thermal head and the platen roller while being in contact with the adhesive layer representing a back surface of the linerless label, and the downstream roll-up prevention member is positioned downstream relative to the platen roller and guides the linerless label away from the platen roller while being in contact with the adhesive layer representing the back surface of the linerless label. At least one of the pair of left and right brackets fixes a position of the roll-up prevention unit relative to the platen roller. The linerless label is set while being nipped between the thermal head and the platen roller in a state where a label tip portion of the linerless label is positioned over the downstream roll-up prevention member of the roll-up prevention unit.

An individual linerless label strip is issued by cutting off the linerless label with a cutting unit positioned downstream relative to the downstream roll-up prevention member. The linerless label positioned upstream relative to the individual linerless label strip is fed in reverse to the upstream side, and the reverse feeding of the linerless label can be stopped in a state where the label tip portion of the linerless label is positioned over the downstream roll-up prevention member.

At least one of the pair of left and right brackets can have a fixture hole for fixing the at least one of the pair of left and right brackets to a printer body of the thermal printer.

The roll-up prevention unit enables a printing region to be formed in a spatial region between the upstream roll-up prevention member and the downstream roll-up prevention member, and the printing region enables the linerless label to be nipped between the thermal head and the platen roller therein.

The upstream roll-up prevention member and the downstream roll-up prevention member can extend across an entire width of the linerless label at a back surface side of the linerless label.

The upstream roll-up prevention member can be composed of a plate or a shaft.

The downstream roll-up prevention member can be composed of a plate.

In the roll-up prevention device and the label tip setting method for the linerless label in the thermal printer according to the foregoing aspects, the roll-up prevention unit including the upstream roll-up prevention member and the downstream roll-up prevention member, which are respectively positioned upstream and downstream relative to the platen roller, can be fixed relative to the platen roller. Therefore, the upstream roll-up prevention member and the downstream roll-up prevention member can prevent the platen roller from rolling up the linerless label, whether the linerless label is fed by the forward or reverse rotation of the platen roller.

Especially in the roll-up prevention device for the linerless label in the thermal printer according to the first aspect, at least one of the pair of left and right brackets in the roll-up prevention unit can fix the position of the roll-up prevention unit relative to the platen roller. This makes it possible to maintain the platen roller and the roll-up prevention unit at stable setting positions, and preserve the function of stably feeding the linerless label even in a long-term operation of the thermal printer.

Especially in the label tip setting method for the linerless label in the thermal printer according to the second aspect, the linerless label is set while being nipped between the thermal head and the platen roller in a state where a label tip portion of the linerless label is positioned over the downstream roll-up prevention member of the roll-up prevention unit. This makes it possible to prevent the platen roller from rolling up the label tip portion of the linerless label from the start of the operation of the thermal printer.

DESCRIPTION OF EMBODIMENTS

The embodiments of the present invention realize a roll-up prevention device and a label tip setting method for a linerless label in a thermal printer that can secure the function of stably feeding the linerless label in forward and reverse directions without the roll-up of the linerless label by the platen roller by incorporating a roll-up prevention unit that includes an upstream roll-up prevention member and a downstream roll-up prevention member, which are respectively positioned upstream and downstream relative to a platen roller, and that can be relatively fixed to the platen roller.

With reference toFIGS. 1 to 3, the following describes a roll-up prevention device20and a label tip setting method for a linerless label in a thermal printer according to a first embodiment of the present invention. Note that the components that are similar to those inFIGS. 7 to 9are given the same reference signs thereas, and a detailed description thereof will be omitted.

FIG. 1is an enlarged lateral cross-sectional view of the roll-up prevention device20. The roll-up prevention device20includes a roll-up prevention unit21.

FIG. 2is a perspective view showing the state where the roll-up prevention unit21is mounted on the platen roller16.FIG. 3is a perspective view of the roll-up prevention unit21. The roll-up prevention unit21is composed of a pair of left and right brackets22positioned at both left and right end sides of the platen roller16, and an upstream roll-up prevention member23and a downstream roll-up prevention member24that span between the brackets22.

As shown inFIG. 3in particular, among the pair of left and right brackets22, one bracket has a roller engagement hole26that is engageable with a roller shaft25of the platen roller16, and the other bracket has an arc-shaped cutout27that is engageable with the roller shaft25. That is to say, as the roll-up prevention unit21is mounted directly on the platen roller16, their relative positions can be maintained and their relative displacements can be minimized for a long period of time.

At least one of the pair of left and right brackets22(inFIG. 3, the right one) can fix the position of the roll-up prevention unit21relative to the platen roller16. Specifically, at least one of the pair of left and right brackets22has a fixture hole28for fixing this bracket22to a printer body1A of the thermal printer1.

That is to say, fixing this bracket22to the printer body1A by inserting, for example, a fixture screw29through the fixture hole28makes it possible to maintain the relative positions of the platen roller16, which is also rotatably fixed to the printer body1A, and this bracket22(i.e., the roll-up prevention unit21).

The upstream roll-up prevention member23is composed of, for example, a metal plate, and its surface has been subjected to non-adhesive treatment, such as application of a release agent.

The upstream roll-up prevention member23is positioned upstream relative to the platen roller16, and its downstream edge23A adjacently faces the platen roller16. The upstream roll-up prevention member23can guide the linerless label2toward the thermal head15and the platen roller16while being in contact with the adhesive layer8representing the back surface of the linerless label2.

The downstream roll-up prevention member24is composed of, for example, a metal plate, and its surface has been subjected to non-adhesive treatment, such as application of a release agent.

The downstream roll-up prevention member24is positioned downstream relative to the platen roller16, and its upstream edge24A adjacently faces the platen roller16. The downstream roll-up prevention member24can guide the linerless label2away from the platen roller16while being in contact with the adhesive layer8representing the back surface of the linerless label2.

The upstream roll-up prevention member23and the downstream roll-up prevention member24extend across the entire width of the linerless label2at the back surface side of the linerless label2.

Note that the upstream roll-up prevention member23and the downstream roll-up prevention member24can further obstruct the roll-up of the linerless label2by the platen roller16when their tip portions facing the platen roller16have an acute angle.

As shown inFIG. 1in particular, the roll-up prevention unit21can form a printing region30in a spatial region between the downstream edge23A of the upstream roll-up prevention member23and the upstream edge24A of the downstream roll-up prevention member24. The linerless label2can be nipped between the thermal head15and the platen roller16in the printing region30. The heating element15A of the thermal head15is positioned in the printing region30. The thermal head15, together with the outer circumferential surface of the platen roller16, can feed and perform printing on the linerless label2that is nipped therebetween with a predetermined pressing force.

As shown inFIG. 1in particular, in a normal operation of issuing an individual linerless label strip2A with the thermal printer1and the roll-up prevention device20configured in the above-described manner, the linerless label2is guided by the guide roller13to the upstream roll-up prevention member23and arrives at the printing region30, printing is performed on the linerless label2, and then the linerless label2that has exited the printing region30is guided by the downstream roll-up prevention member24. Consequently, the linerless label2can arrive at the cutting unit6without being rolled up by the platen roller16.

The cutting unit6issues the individual linerless label strip2A by cutting off the linerless label2. Thereafter, in the operation of feeding the linerless label2in reverse to the printing start position in the printing region30, the linerless label2is guided by the upstream roll-up prevention member23and hence is not rolled up by the platen roller16.

The cutting unit6, which is positioned downstream relative to the downstream roll-up prevention member24, issues the individual linerless label strip2A by cutting off the printed linerless label2. The linerless label2positioned upstream relative to the individual linerless label strip2A is fed in reverse to the upstream side by rotating the platen roller16in reverse, and the reverse feeding of the linerless label2is stopped in the state where the label tip portion2B of the linerless label2is positioned over the downstream roll-up prevention member24(see a virtual line inFIG. 1).

That is to say, the linerless label2can be set in the printing region30while being nipped between the thermal head15and the platen roller16in the state where the label tip portion2B of the linerless label2is positioned over the downstream roll-up prevention member24of the roll-up prevention unit21.

When the thermal printer1has been in a printing standby state for a long period of time, at the start of the next printing, the platen roller16is slightly rotated in reverse to cause backward feeding of the linerless label2, and then the label tip portion2B of the linerless label2is arranged to hang over the downstream roll-up prevention member24. This can prevent the linerless label2from sticking to the platen roller16at the start of a printing operation.

In the present embodiment, the upstream roll-up prevention member can be composed of a shaft.

That is to say,FIG. 4is an enlarged lateral cross-sectional view of a roll-up prevention device40for a linerless label in a thermal printer according to a second embodiment of the present invention. The roll-up prevention device40includes a roll-up prevention unit41.

FIG. 5is a perspective view showing the state where the roll-up prevention unit41is mounted on the platen roller16.FIG. 6is a perspective view of the roll-up prevention unit41. The roll-up prevention unit41is composed of the aforementioned pair of left and right brackets22positioned at both left and right end sides of the platen roller16, an upstream roll-up prevention member42that spans between the brackets22and is composed of a metal shaft having a circular cross-section, and the aforementioned downstream roll-up prevention member24.

A surface of the upstream roll-up prevention member42has been subjected to non-adhesive treatment, such as application of a release agent. The upstream roll-up prevention member42is rotatable with respect to the pair of left and right brackets22, and can smoothly guide the linerless label2.

Except for the upstream roll-up prevention member42composed of the shaft, the roll-up prevention device40is similar to the aforementioned roll-up prevention device20(FIG. 1), and thus similar components are given the same reference signs.

Similarly to the roll-up prevention device20, the roll-up prevention device40configured in the above-described manner can fulfill the function of stable feeding without the roll-up of the linerless label2by the platen roller16in the operation of printing on the linerless label2and the operation of setting the linerless label2at a printing position through the forward and reverse rotations of the platen roller16.

Especially because the upstream roll-up prevention member42is composed of the shaft, the contact resistance between the upstream roll-up prevention member42and the linerless label2that is guided while being in contact with the upstream roll-up prevention member42is small, and the roll-up can be prevented in a more stable manner.

The above-described embodiments of the present invention merely represent a part of example applications of the present invention, and the specific configurations of the above-described embodiments are not intended to limit a technical scope of the present invention.

The present application claims the benefit of priority from Japanese Patent Application No. 2014-72563, filed Mar. 31, 2014 with the Japan Patent Office, the disclosure of which is incorporated herein by reference in its entirety.