CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a 35 U.S.C. §§371 national phase conversion of PCT/JP2007/075071, filed Dec. 27, 2007, which claims priority of Japanese Application No. 2007-010159, filed Jan. 19, 2007, incorporated by reference herein. The PCT International Application was published in the Japanese language. 
     TECHNICAL FIELD 
     Background Art 
     In a label printer, a continuous label strip (hereinafter also referred to as a “paper sheet”) in which labels with a predetermined length are adhered removably to a long strip-shaped mount sheet (separator) at regular intervals, for example, is used as a print medium. The paper sheet is conveyed by platen rollers, and the labels are printed using a thermal head provided so as to oppose the platen rollers across the paper sheet. Moreover, in some cases, printed labels are automatically peeled off from the mount sheet using a label peeling mechanism (label peeling unit). 
     As a related technology, a paper label peeling apparatus that can be fitted to an existing thermal printer is disclosed in Patent Document JP-A-7-132919 (p. 1, FIG. 1). In this paper label peeling apparatus, a pressure roller, a feed roller, and a capstan roller are rotatably supported onto a frame by shafts. The pressure roller and the feed roller are coupled to each other by a gear, and the feed roller and the capstan roller are brought into contact with each other by an appropriate pressing force. A peeling part is provided so as to oppose the feed roller, and the pressure roller is in contact with a platen of the thermal printer. This paper label peeling apparatus makes it possible to use an existing thermal printer as a label printer. Moreover, it is described that it is possible to drive the paper label peeling apparatus without necessitating a dedicated drive source, such as a motor, or a control circuit by firmware. 
     A problem with the paper label peeling apparatus of this Patent Document, however, is that it is difficult to insert the paper sheet through the paper label peeling apparatus because the locations of the peeling part for peeling labels and the rollers for conveying the paper sheet are close to each other. 
     SUMMARY OF THE INVENTION 
     Objects of the Invention 
     In view of the foregoing point, it is an object of the invention to make easy inserting of paper sheets in a label peeling unit fitted to a label printer or the like and used for peeling labels from a mount sheet. It is also an object of the invention to provide a label printer in which such a label peeling unit is fitted. 
     Description of the Invention 
     In order to solve the foregoing problems, the invention provides, in accordance with one aspect thereof, a label peeling unit fitted to a paper sheet conveying device for conveying a continuous label strip in which labels are adhered removably on a mount sheet. The unit is used for peeling the labels. The label peeling unit comprises the following elements. An attachment body is attached to a case of the paper sheet conveying device. A movable body is movable while engaging the attachment body. The movable body is urged by a spring, whereby it stops in a closed state or in an open state with respect to the attachment body. A label peeling body is fitted to the movable body and is contacted by the mount sheet of the continuous label strip conveyed by the paper sheet conveying device so that the mount sheet is bent, to thereby peel a portion of a label from the mount sheet. A mount sheet conveying roller is attached to the movable body freely rotatably. The conveying roller rotates while being in contact with a platen roller of the paper sheet conveying device via the mount sheet, to thereby convey the mount sheet and discharge it outside. 
     In another aspect, the invention provides a label printer for conveying a continuous label strip in which labels are adhered removably to a mount sheet, and performing printing on the labels. The label printer comprises the following elements. A case in which an enclosing unit is formed for enclosing a continuous label strip coiled in a roll form. A platen roller is rotated and driven by a motor provided in the case, to thereby convey the continuous label strip. A print head prints on labels while sandwiching the continuous label strip between it and the platen roller. A front face cover is attached openably/closably to the case. A label peeling unit according to the invention is attached to the case within the front face cover. 
     Advantageous Effects of the Invention 
     According to the invention, a label peeling body for peeling labels and amount sheet conveying roller for conveying a mount sheet and discharging it outside are mounted to a movable body that is capable of parallel shifting and rotational shifting relative to an attachment body. Therefore, inserting of paper sheets is made easy in the label peeling unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing the outline of a label printer in which a label peeling unit according to one embodiment of the invention is fitted. 
         FIG. 2  is a plan view showing the structure of the main unit side of the label printer shown in  FIG. 1 . 
         FIG. 3  is a perspective view showing the label peeling unit in the state in which a front face cover of the label printer shown in  FIG. 1  is open. 
         FIG. 4  is a view showing the state in which the front face cover and a movable body are open to load a paper sheet. 
         FIG. 5  is a perspective view showing component parts of the label peeling unit. 
         FIG. 6  is a perspective view showing component parts (springs) of the label peeling unit. 
         FIG. 7  is a perspective view showing the structure of the assembled label peeling unit. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereinbelow, embodiments of the invention are described with reference to the drawings. It should be noted that the same component parts are designated by the same reference numerals, and the explanations thereof will be omitted. 
     The label peeling unit according to the invention is used by being fitted in a label printer or the like in which a continuous label strip is conveyed and the labels are printed, or in a peeling device for conveying a continuous label strip and peeling the labels (these devices are referred to as “paper sheet conveying devices” in the present application). The following embodiments, however, describes the cases in which the label peeling unit is fitted and used in the label printer. 
       FIG. 1  is a perspective view showing the outline of a label printer in which a label peeling unit according to one embodiment of the invention is fitted. As shown in  FIG. 1 , a label printer  1  comprises a case  2 , a paper sheet retaining mechanism  5  for freely rotatably retaining a paper roll in which a continuous label strip (paper sheet) is coiled in roll form, a platen roller  18  for conveying the paper sheet, a label sensor  19  for detecting the location of a label, and a front face cover  3  and an upper face cover  4  that are attached pivotably relative to the case  2 , in the direction shown by the arrow. 
     A peeling roller  31  for pressing the surface of a paper sheet downward is attached rotatably to the front face cover  3 , and in addition, the front face cover  3  is provided with a display unit  32  such as LEDs, an operation unit  33  such as operation keys, and a mount sheet discharge port  34  for discharging a mount sheet. A recessed portion  35  is formed in at least a portion of the front face cover  3  so that the labels can be easily removed. 
     A thermal head  41  and a detection protrusion  42  are attached to the upper face cover  4 , and the upper face cover  4  is provided with a transparent window  43  for confirming the condition of the paper sheets. 
     The case  2  is provided with a cover-open/close lever  23  for opening/closing the upper face cover  4 , and a cover-open/close sensor  24  for detecting opening/closure of the upper face cover  4 . The cover-open/close sensor  24  includes a light-emitting element and a photodetector element. Because of blocking of light by the detection protrusion  42 , it can detect that the upper face cover  4  is closed, so it is possible to prevent the printing operation from being performed when the upper face cover  4  is kept open (i.e., when the upper face cover  4  is not closed completely). 
       FIG. 2  is a plan view showing the structure of the main unit side of the label printer shown in  FIG. 1 . A paper roll enclosing recess  2   a  for enclosing a paper roll  20   r , in which a continuous label strip  20  is coiled in roll form, is formed in the case  2 . The paper sheet retaining mechanism  5  is installed in the paper roll enclosing recess  2   a  so as to retain the paper roll  20   r  freely rotatably. 
     In the paper sheet retaining mechanism  5 , two paper sheet side face guides  6  for restricting the location of the paper roll  20   r  along the width direction (shaft direction) are provided so that the locations thereof can be varied according to the width of the paper sheet. In addition, a paper sheet upper face guide  6   a  is formed integrally with at least one of the paper sheet side face guides  6 . The paper sheet upper face guide  6   a  prevents fluttering of the paper sheet by pressing a widthwise end portion of the continuous label strip  20  that has been pulled out from the paper roll  20   r  downwardly, so as to make better the detection operation of the label sensor  19  (see  FIG. 1 ), disposed at an opposite location across the continuous label strip  20 . 
     Sliding members  11  along the widthwise direction of the paper roll  20   r  are provided integrally with the lower ends of the paper sheet side face guides  6 , and these sliding members  11  are fitted respectively in a pair of guide grooves  12 , which are formed in the bottom face of the paper roll enclosing recess  2   a , freely slidably. Thereby, the two paper sheet side face guides  6  are allowed to be capable of shifting in the directions in which they approach each other or move away from each other, while keeping the parallel condition. 
     Two racks  13  are provided respectively for the two paper sheet side face guides  6 , along the bottom face of the paper roll enclosing recess  2   a , and a pinion  14  that meshes with these racks  13  is provided freely rotatably at a location at which the racks  13  face each other. As a result, when one of the paper sheet side face guides  6  is shifted a certain distance in a desired direction, the other one of the paper sheet side face guides  6  also shifts by the same distance in the opposite direction. An engaging protrusion (not shown) provided on the paper sheet side face guide  6  engages with an engaging groove (not shown) provided in the paper roll enclosing recess  2   a , whereby the widthwise locations of the paper sheet side face guides  6  are determined. 
     In addition, a platen roller retaining portion  17  is attached to the case  2 , and two platen roller bearings  18   a  are retained by the platen roller retaining portion  17 , and the platen roller  18  is retained rotatably by these platen roller bearings  18   a.    
       FIG. 3  is a perspective view showing the label peeling unit in the state in which the front face cover of the label printer shown in  FIG. 1  is open. A label peeling unit  50  has an attachment body  51  attached to the case  2  of the label printer by screw-fastening, a movable body  52  retained in such a condition as to be capable of parallel shifting and rotational shifting while engaging with the attachment body  51 , a label peeling body  53  attached rotatably to the movable body  52 , a mount sheet conveying roller  54  that is attached freely rotatably to the movable body  52  and is driven-rotated by making contact with the platen roller  18 , which is rotation-driven by a motor that is not shown in the drawing, and a guide plate  55  located below the movable body  52  and attached freely rotatably to the attachment body  51 . 
     By being urged by a spring, the movable body  52  can stop either in a closed state or in an open state with respect to the attachment body  51 . In  FIG. 3 , the movable body  52  is in a closed state with respect to the attachment body  51 . At least one pressing part that is pressed down when shifting the movable body  52  is provided integrally with the movable body  52 . In  FIG. 3 , two pressing parts  52   a  are shown. By pressing down the pressing parts  52   a  toward the attachment body  51  side, the movable body  52  can be opened frontward. 
       FIG. 4  is a view showing the state in which the front face cover and the movable body are open to insert a paper sheet. By opening the movable body  52  frontward, the mount sheet conveying roller  54  that has been in contact with the platen roller  18  can be separated from the platen roller  18 , so it becomes possible to insert a paper sheet through the label peeling unit. As shown in  FIG. 4 , the inserted continuous label strip  20  is folded over at the fore-end of the label peeling body  53  and is thereby bent considerably. The movable body  52  is closed by pressing the pressing part  52   a  toward the label printer side after inserting the paper sheet. Moreover, by closing the front face cover  3  as shown in  FIG. 1 , the peeling roller  31  shifts above the label peeling body  53  ( FIG. 3 ) and presses the paper sheet in a direction toward the label peeling body  53  (downward) at a location opposite to the label peeling body  53 . 
     When a paper sheet is conveyed under this condition, a label is peeled off from the mount sheet at the time when the paper sheet passes through the bent portion, and the conveying of the paper sheet is temporarily stopped in the state in which a portion of the label is removably adhered on the mount sheet and retained on the label peeling body  53 . Also, a peeling sensor  56  secured to the movable body  52  is used to detect whether or not the label has been removed. A light absorption part  52   b  for absorbing light is formed in the movable body  52  in order to prevent malfunctions of the peeling sensor  56  resulting from the entry of extraneous light or the irregular reflection of light. 
     While the peeling sensor  56  is detecting the label, the next label is not issued. When the peeled label is removed by the operator or the like and the peeling sensor  56  no longer detects the label, the next label is printed and conveyed to the label peeling unit  50 . As shown in  FIG. 1 , the recessed portion  35  for making removal of the label easy is formed in at least a portion of the front face cover  3 . Therefore, the label can be removed easily by inserting a finger into the recessed portion  35 , even if the label has a short length along the conveyance direction. 
       FIGS. 5(   a ) through  5 ( e ) and  FIGS. 6(   a ) and ( b ) are perspective views showing a plurality of component parts of the label peeling unit, and  FIG. 7  is a perspective view showing the structure of the label peeling unit assembled using the component parts. As shown in  FIG. 5(   d ), the attachment body  51  has a plurality of screw holes  51   a  formed therein and used when attached to the case of the label printer, two screw holes  51   b  formed therein and used for attaching the movable body  52 , two engaging grooves  51   c  for engaging respectively with two engaging protrusions  52   d  (see  FIG. 5(   c )) of the movable body  52 , two mounting holes  51   d  for attaching the guide plate  55  thereto, and an engaging piece  51   e  for engaging with one end of an extension spring  61 . 
     As shown in  FIG. 5(   c ), the movable body  52  has the two pressing parts  52   a  on which a plurality of protruding portions are formed thereon as non-slip parts, the light absorption part  52   b  for absorbing light, two elongated holes  52   c  for attaching the movable body  52  slidably to screws (not shown) attached to the screw holes  51   b  of the attachment body  51 , two engaging protrusions  52   d  protruding inwardly so as to engage respectively with the two engaging grooves  51   c  of the attachment body  51 , shaft holes  52   e  for inserting the shaft of the mount sheet conveying roller  54  (see  FIG. 5(   b )), and an engaging piece  52   f  for engaging with the other end of the extension spring  61 . 
     As shown in  FIG. 5(   a ), the label peeling body  53  has shaft grooves  53   a  formed therein for inserting the shaft of the mount sheet conveying roller  54 , protruding portions  53   b  formed thereon, and inclined surfaces  53   c  formed thereon. As shown in  FIG. 5(   e ), the guide plate  55  has mounting pieces  55   a  formed thereon. 
     The extension spring  61  shown in  FIG. 6(   a ) is hooked between the engaging piece  51   e  of the attachment body  51  and the engaging piece  52   f  of the movable body  52  so as to urge the movable body  52  toward the attachment body  51  side (upward). A torsion spring  62  shown in  FIG. 6(   b ) is retained by the shaft of the mount sheet conveying roller  54 , so as to urge the label peeling body  53  in a direction away from the movable body  52  (upward). 
     Referring to  FIGS. 5 to 7 , mount screws are inserted in the screw holes  51   b  of the attachment body  51  through the elongated holes  52   c  of the movable body  52 . At the same time, the engaging protrusions  52   d  of the movable body  52  engage with the engaging grooves  51   c  of the attachment body  51 . Thus, the movable body  52  can perform parallel shifting and rotational shifting relative to the attachment body  51 . In the state shown in  FIG. 7 , the engaging protrusions  52   d  are positioned in upper portions of the L-shaped engaging grooves  51   c  by the tension of the extension spring  61 , and the movable body  52  is in a closed state with respect to the attachment body  51 . 
     By pressing down the pressing parts  52   a  by the operator, the engaging protrusions  52   d  move to lower portions of the L-shaped engaging grooves  51   c , the movable body  52  pivots by the tension of the extension spring  61 , and the engaging protrusions  52   d  move to the front ends of the lower portions of the L-shaped engaging grooves  51   c . Thereby, the movable body  52  opens frontward. As a result, the gap between the platen roller  18  and the mount sheet conveying roller  54  supported by the movable body  52  is widened, so inserting a paper sheet through the label peeling unit becomes easy. When the operator presses the pressing parts  52   a  toward the label printer side after inserting the paper sheet, the movable body  52  closes again. 
     The shaft of the mount sheet conveying roller  54  is inserted through the shaft holes  52   e  of the movable body  52 , the shaft grooves  53   a  of the label peeling body  53 , and the torsion spring  62 . Thereby, the mount sheet conveying roller  54  is attached freely rotatably to the movable body  52 , and the label peeling body  53  is attached rotatably to the movable body  52  taking the shaft of the mount sheet conveying roller  54  as the axis of rotation. Further, the label peeling body  53  is urged upwardly (in the opposite direction to the moving direction of the mount sheet) by the torsion spring  62 . The mount sheet conveying roller  54  rotates by making contact with the platen roller via a paper sheet so that it conveys the mount sheet and discharges it outside. 
     In the process of closing the front face cover, both ends of the peeling roller  31  (see  FIG. 3 ) move along the inclined surfaces  53   c  of the label peeling body  53  and resist the upward force by the torsion spring  62 . Also, the protruding portions  53   b  of the label peeling body  53  comes into contact with the platen roller retaining portion  17  (see  FIG. 3 ), so the pivoting movement by the torsion spring  62  is restricted. Moreover, by inserting the mounting pieces  55   a  of the guide plate  55  into the mounting holes  51   d  of the attachment body  51 , the guide plate  55  is attached freely rotatably to the attachment body  51 . The guide plate  55  guides the discharged mount sheet toward the mount sheet discharge port  34  (see  FIG. 1 ).
A label peeling unit having an installation body: a movable body movable while engaging with the installation body and stopping in a closed state or an open state in which the movable body is closed or open relative to the installation body; a label peeling body installed on the movable body and allowing backing paper of a continuous label body, which is conveyed by the paper sheet conveyance device, to be in contact with the label peeling body to bend the backing paper for peeling a part of a label off the backing paper; and a backing paper conveyance roller rotatably installed on the movable body and rotating while being in contact with a platen roller of the paper sheet conveyance device with the backing paper in between to thereby convey the backing paper and discharge it to the outside. The label peeling unit facilitates loading of paper sheets.