1. Field of the Invention
The present invention relates to an adhesive label issuing device that issues an adhesive label, and a printer including the adhesive label issuing device.
2. Description of the Related Art
Conventionally, for example, as a label sheet for adhesive labels used for, for example, a POS label for food, a logistics/transportation label, a medical label, a baggage tag, and an indication label for bottles and cans, a linerless type label sheet not using a liner (separator) has been known. As the linerless type label sheet, in general, there is a silicon top type label sheet in which the surface of a label recording surface is coated with a release agent such as a silicon resin, to thereby prevent adhesion between the recording surface and an adhesive layer provided on a rear surface of the recording surface when the label is rolled into a roll shape. In recent years, there has been known a label sheet in which a thermally activated adhesive layer, which exhibits adhesiveness by heating, is provided on a rear surface of a label having a recording surface of a thermosensitive color-developing type. In the label sheet having an adhesive layer made of a thermally activated adhesive, the recording surface is allowed to develop color with heat to print a bar-code, characters, etc. thereon, and the thermally activated adhesive layer is allowed to exhibit adhesive strength by heating.
Further, in recent years, in addition to a label sheet provided with the above-mentioned thermally activated adhesive layer, a label sheet has been proposed in which a liner is omitted by covering the surface of an adhesive layer of the label sheet with a coating layer. In this label sheet, the coating layer on the rear surface of the label is heated, to thereby remove the coating layer to expose the adhesive layer. Consequently, adhesive strength can be exhibited.
Japanese Patent Application Laid-Open No. 2003-316265 describes an example of a printer for printing/issuing an adhesive label through use of the above-mentioned label sheet having the thermally activated adhesive layer formed therein or the above-mentioned label sheet in which the surface of the adhesive layer is covered with the coating layer. It is known that this type of the printer includes a roll accommodating part for accommodating a sheet roll obtained by rolling a band-shaped linerless type label sheet into a roll shape, a printing unit for performing printing by heating the label sheet unrolled from the sheet roll from the thermosensitive color-developing surface side, a cutter unit for cutting the printed label sheet to obtain an adhesive label with a desired length by allowing the label sheet to pass therethrough, and an adhesive strength exhibiting unit for allowing the label sheet to exhibit adhesive strength by heating an adhesive layer. The printing unit and the adhesive strength exhibiting unit described above respectively include a thermal head and a platen roller, and are configured to: perform printing when a printing surface of the label sheet passes through a region between the thermal head and the platen roller of the printing unit; and thermally activate the adhesive layer when the label sheet passes through a region between the thermal head and the platen roller of the adhesive strength exhibiting unit, or remove the coating layer on the surface of the adhesive layer to allow the adhesive label to exhibit adhesive strength.
By the way, in the above-mentioned printer, when the label sheet is cut by the cutter unit, the label sheet is cut at a right angle with respect to the length direction of the sheet, and hence it is necessary to stop the transportation of the label sheet temporarily so as to perform a cutting operation. If a portion to be the trailing end of the adhesive label is cut by the cutter unit, the leading end of the label sheet (adhesive label) has proceeded up to the position of the thermal head of the adhesive strength exhibiting unit. When the label sheet (adhesive label) remains inserted between the thermal head and the platen roller of the adhesive strength exhibiting unit, the label sheet is pulled by the platen roller of the adhesive strength exhibiting unit. Therefore, it is necessary to stop the transportation of the label sheet (adhesive label) temporarily. In this case, there is a fear that the thermosensitive color-developing surface is discolored with heat from the thermal head (heat source) of the adhesive strength exhibiting unit, and the thermally activated adhesive layer may adhere to the thermal head to cause transportation defects such as sheet jam.
Then, as for the above-mentioned conventional printer, there is proposed a configuration in which a sheet loosening unit for loosening the label sheet is provided between the cutter unit and the adhesive strength exhibiting unit. The sheet loosening unit includes an upstream sheet-passage part (guide) which is placed on the downstream side in the sheet transporting direction of the cutter unit and through which the label sheet passes, and a downstream sheet-passage part (guide) which is placed on the upstream side in the label transporting direction of the adhesive strength exhibiting unit and through which the label sheet passes. The upstream sheet-passage part and the downstream sheet-passage part described above are respectively placed so that the respective sheet-passage directions are aligned on the same line, and the label sheet passed from the upstream sheet-passage part to the downstream sheet-passage part can be loosened between the upstream sheet-passage part and the downstream sheet-passage part. Thus, when the adhesive label with a large length is issued, the label sheet is sent while being loosened between the upstream sheet-passage part and the downstream sheet-passage part, with the result that the label sheet can proceed without being stopped in the adhesive strength exhibiting unit positioned on the downstream side during cutting of the label sheet.
Further, in the above-mentioned adhesive label issuing device, although it is not necessary to loosen the label sheet when the length of the adhesive label is small, the adhesive label needs to have at least a length from a blade tip position of the cutter unit to the downstream sheet-passage part.
In the above-mentioned conventional printer (adhesive label issuing device), when the label sheet is loosened too much between the upstream sheet-passage part and the downstream sheet-passage part, a loosened portion of the label sheet is bent in the middle to enter the downstream sheet-passage part, which may cause transportation defects such as sheet jam. In particular, at low temperature (for example, 5° C. or less), the label sheet becomes hard, and hence the loosened part of the label sheet is bent easily. Thus, it is necessary to limit the length of the adhesive label to be issued by the adhesive label issuing device to such a length that the loosened part of the label sheet is not bent.
Further, as the interval between the upstream sheet-passage part and the downstream sheet-passage part is enlarged, bending of the loosened part of the label sheet can be prevented even when the label sheet is loosened greatly. In this case, although the upper limit of the length of the adhesive label becomes larger, the lower limit of the length of the adhesive label becomes larger by the enlarged interval between the upstream sheet-passage part and the downstream sheet-passage part. On the contrary, as the interval between the upstream sheet-passage part and the downstream sheet-passage part is narrowed, the lower limit of the length of the adhesive label becomes smaller. However, the upper limit of the length of the adhesive label becomes smaller because the loosened part of the label sheet is bent easily. Thus, in the above-mentioned conventional adhesive label issuing device, the freedom degree of the length of the adhesive label is low.
The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to provide an adhesive label issuing device and a printer capable of enhancing reliability by preventing transportation defects of a label sheet, enhancing a degree of freedom of a length of an adhesive label, and realizing reduction in size.