Patent Publication Number: US-7905976-B2

Title: Label peeling method for label paper sheet and label printer

Description:
TECHNICAL FIELD 
     The present invention relates to a method wherein, while conveying a label sheet including a base sheet and a label affixed thereto, a printing operation is performed on the label and, after then, the label is peeled from the base sheet, and a label printer suitable for realizing the label peeling method. 
     BACKGROUND ART 
     Necessary information is printed on the label of the above-mentioned label sheet, the label is peeled off from the base sheet and the thus peeled label is then affixed to goods. There is provided a label printer wherein the operation to print the necessary information on the label and the operation to peel off the label from the base sheet are carried out successively. 
     Generally, there is known a label printer of such a type which pulls out a label sheet wound in a roll shape, prints necessary information on a label mounted on the label sheet while conveying the label sheet, and, after printed, bends the conveying path of the label sheet at an acute angle, whereby the label is allowed to move straight due to its own rigidity and peel off from the base sheet. 
     In such label printer, since the adhesive power of the label with respect to the base sheet is strong, or since the end edge of the label bites into the base sheet when the label is formed by punching only an adhesive sheet mounted on the base sheet, the label is difficult to peel off from the base sheet. And, when the label does not peel off from the base sheet smoothly, not only the printed label is not discharged properly but also a trouble occurs in conveying the label sheet to thereby cause the label printer to stop. 
     Thus, as a printer which is capable of preventing the above-mentioned problems, there is provided a printer wherein, before the whole of the label is peeled off from the base sheet, holds and lifts at least one side of the label to thereby peel a part of the label once and, after then, peels the label wholly from the base sheet (Patent Document 1). 
     Patent Document: JP-UM-A-2-129010 
     DISCLOSURE OF THE INVENTION 
     Problems that the Invention is to Solve 
     In the peeling apparatus disclosed in the above-cited document, since it is necessary to provide a peel aid device that peels the label preliminarily, increases the number of parts and thus increases the size of the apparatus is necessary. Thus, there has been demanded the development of a technology which is capable of peeling the label in a simple configuration without incurring the increased number of parts and the increased size of the apparatus. 
     In view of the above, it is one object of the invention to provide a label peeling method for label sheet which is capable of peeling a label securely in a simple configuration without providing a separate device for peeling the label, and a label printer on which the method is specifically reflected. 
     Means for Solving the Problems 
     According to an embodiment of the invention, the label peeling method for label sheet includes: conveying a label sheet including a base sheet and a label affixed to the base sheet along a conveying path that is bent at a bent portion; and performing a printing operation on the label from a beginning portion of printing while conveying the label sheet, wherein the conveying of the label sheet and the printing operation are stopped once in a stopping state where the label sheet is conveyed until a conveying-direction leading end portion of the label reaches a downstream side of the bent portion of the conveying path, after a stopping state is held for a predetermined time, the conveying of the label sheet and the printing operation are resumed so that the label is peeled from the base sheet at the bent portion of the conveying path. 
     According to the above label peeling method, when only the conveying-direction leading end portion of the label is fed more downstream than the bent portion of the conveying path, normally, the leading end portion is allowed to peel from the base sheet due to its own rigidity without being bent. That is, the label is preliminarily peeled in this manner. Therefore, even in a state where the label is difficult to peel from the base sheet due to the strong adhesion thereof, the preliminarily peeling state, that is, the state, in which the conveying-direction leading end portion of the label is fed more downstream than the bent portion of the conveying path, is held continuously for a predetermined time, which makes it possible to cause a phenomenon that the leading end portion of the label peels gradually from the base sheet. In this manner, after the label is peeled preliminarily, the conveying of the label sheet is resumed, and a printing operation is performed while conveying the label sheet. This makes it possible to peel the preliminarily peeled label securely from the base sheet. 
     Also, according to an embodiment of the invention, a label peeling method for label sheet includes: conveying a label sheet including a base sheet and a label affixed to the base sheet along a conveying path that is bent at a bent portion; and performing a printing operation on the label while conveying the label sheet, wherein the label sheet is conveyed until a conveying-direction leading end portion of the label reaches a downstream side of the bent portion of the conveying path, an operation to reversely convey the label sheet to a beginning portion of printing at an upstream side in a conveying direction is performed at least once, and thereafter, the printing operation on the label is performed while the label sheet is conveyed so that the label is peeled from the label sheet. 
     According to the present label peeling method, after the label sheet is conveyed until only the conveying-direction leading end portion of the label reaches the downsstream side of the bent portion of the conveying path, an operation to reversely convey the label sheet to a beginning portion of printing at the upstream side in the conveying direction thereof is carried out at least once, preferably, the operation may be carried out several times; and, after then, the printing operation on the label is performed while the label sheet is conveyed so that the label is peeled from the label sheet. Thanks to a series of operations in which the leading end portion of the label is fed from the bent portion to the downstream side thereof, the label sheet is then conveyed reversely, and the regular label sheet conveying is next started, the preliminary peeling for peeling the leading end portion of the label from the base sheet can be attained securely and, therefore, in the regular label peeling operation to be performed later, the label is allowed to securely peel from the base sheet. 
     Next, according to an embodiment of the invention a label printer includes: a conveying path along which a label sheet in conveyed, the label sheet including a base sheet and a label affixed to the base sheet, the conveying path being bent at a bent portion; a print mechanism that is disposed in an intermediate portion of the conveying path and performs a printing operation on the label from a beginning portion of printing; a peel mechanism disposed on a downstream side of the conveying path with respect to the print mechanism and peels the label from the base sheet at the bent portion of the conveying path; a label sheet conveying mechanism that conveys the label sheet along the conveying path; and a control unit that controls the label sheet conveying mechanism and the print mechanism such that the label sheet is conveyed until a conveying-direction leading end portion of the label reaches a downstream side of the peel mechanism, the conveying of the label sheet is stopped once at this state, and thereafter, the conveying of the label sheet while performing the printing operation is resumed. 
     According to an embodiment of the invention, a label printer includes: a conveying path along which a label sheet is conveyed, the label sheet including a base sheet and a label affixed to the base sheet, the conveying path being bent at a bent portion; a print mechanism that is disposed in an intermediate portion of the conveying path for performing a printing operation on the label; a peel mechanism that is disposed on a downstream side of the conveying path with respect to the print mechanism and peels the label from the base sheet at the bent portion of the conveying path; a label sheet conveying mechanism that conveys the label sheet along conveying path; and a control unit that controls the label sheet conveying mechanism and the print mechanism such that the label sheet is conveyed until a conveying-direction leading end portion of the label reaches a downstream side of the peel mechanism, an operation to reversely convey the label sheet to a beginning portion of printing at an upstream side in a conveying direction is performed at least once, and thereafter, the label sheet is conveyed while performing the printing operation. 
     Effects of the Invention 
     According to the invention, by bending the conveying path of the label sheet, prior to execution of a regular label peeling operation to peel the label, only the conveying-direction leading end portion of the label is conveyed to the downstream side of the bent portion of the conveying path, and this state is held for a predetermined time, or the label sheet is conveyed reversely from this state and is then conveyed again, thereby peeling the leading end portion of the label preliminarily. Whereby, in the regular label peeling operation to be performed later, the label can be peeled from the base sheet surely. Since a device for preliminarily peeling the label is not provided separately but the preliminary label peeling is attained through the conveying operation of the label sheet, the label can be peeled without increasing the number of parts and the size of the label printer. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Now, description will be given below of an embodiment of a label printer according to the invention with reference to the accompanying drawings. 
       FIG. 1  shows a label printer  1  according to an embodiment of the invention,  FIG. 2  is an enlarged view of the part II shown in  FIG. 1 , and  FIG. 3  shows the procedure for setting a label sheet  10  in the label printer  1  in the order of  FIG. 3(   a ) to  3 ( d ). 
     As shown in  FIGS. 1 and 3 , the label printer  1  includes a rectangular-shaped casing  20  for storing the label sheet  10 . The casing  20  includes two covers  30  and  40  (upper cover and lower cover) for closing the upper opening of the casing  20  through a hinge shaft  21  extending in the right and left direction (in  FIGS. 1 and 3 , in the front and rear direction) in such a manner that the two covers  30  and  40  are capable of opening and closing. These upper and lower covers  30  and  40  share the single hinge shaft  21  and are capable of rotating independently from each other so that two covers  30  and  40  are opened and the label sheet  10  can be stored in a label sheet storage part  22  formed in the casing  20 . 
     The label sheet  10  including a base sheet  11  and a large number of labels  12  affixed on one side of the base sheet  11 . The label sheet  10  is stored in such a manner that it is wound in a roll state on a core member  13  while the labels  12  are arranged on the outer peripheral side thereof. The label sheet  10  is dropped down and stored in the label sheet storage part  22  in such a manner that the core member  13  is held substantially parallel to the hinge shaft  21  and also in such an attitude that the front end portion of the label sheet  10  can be pulled upward from below. The upper and lower covers  30  and  40  can be respectively engaged with the casing  20  by an engaging mechanism (not shown) and the fully closed state of the casing  20  shown in  FIG. 1  is held when they are in an engaged state. 
     The label printer  1  includes a print mechanism  50  for performing a printing operation on the labels  12 . This print mechanism  50  mainly includes a platen roller  51  mounted on the lower cover  40 , and a print head  52  of a thermal type. 
     The lower cover  40 , as shown in  FIG. 1 , includes a base end portion  41  extending forward horizontally from its mounting portion on the hinge shaft  21  in the closed state of the lower cover  40 , an inclined portion  42  which is inclined from the base end portion  41  in such a manner that the front thereof lowers down forwardly, an R portion  43  which is curved from the inclined portion  42  over to the front end portion of the lower cover  40  in such a manner that the front thereof rises up forwardly, and right and left triangular-shaped side wall portions  44  respectively rising from the two end edges of a portion extending from the intermediate portion of the inclined portion  42  to the R portion  43 ; and, the rear end portion of the base end portion  41  is rotatably mounted on the hinge shaft  21  in such a manner that it is capable of rotating freely. On the front end portion of the lower cover  40 , there is rotatably mounted the platen roller  51  while the axial direction of the platen roller  51  extends parallel to the hinge shaft  21 . 
     The print head  52  is mounted on the upper portion of the inner surface of the front wall portion  20   a  of the casing  20  and is urged backward (in  FIG. 1 , to the right direction) by a spring (not shown). When the lower cover  40  is closed, the platen roller  51  is allowed to face the print head  52 , while the print head  52  is elastically pressed against the platen roller  51 . The label sheet  10 , which has been pulled out from the roll state thereof, is held by and between the platen roller  51  and print head  52  and, as the platen roller  51  is rotated clockwise in  FIG. 1 , the label sheet  10  is conveyed upward. The platen roller  51  is rotated by a conveying motor  53  (which will be discussed later) mounted on the casing  20  and a drive mechanism (not shown) including reduction gear groups and, when the lower cover  40  is closed, the platen roller  51  can be connected to the drive mechanism. This drive mechanism and platen roller  51  cooperate together in configuring a label sheet conveying mechanism. 
     Between the front ends upper portions of the right and left side walls  44  of the lower cover  40 , there is mounted a fine bar-shaped peel bar  60  which extends parallel to the platen roller  51 . This peel bar  60  is used to divide the label sheet  10  into the base sheet  11  and labels  12  and, when the lower cover  40  is closed the peel bar  60  is disposed at a position which exists just above the print mechanism  50  and where the label sheet  10  has just passed through the print mechanism  50 . The label sheet  10  is conveyed from below in such a manner that it passes through the print mechanism  50 ; and, the conveying path of the label sheet  10  existing on the downstream side of the print mechanism  50  extends along the peripheral surface of the front side of the peel bar  60  and then extends backward, whereby the conveying path is bent at an acute angle in the portion thereof where it passes through the peel bar  60 . 
     The upper cover  30  includes right and left side wall portions  31  respectively disposed on the two sides of the lower cover  40 , and a ceiling plate portion  32  provided across these side walls  31 , while the rear end portions of the respective side walls  31  are rotatably mounted on the hinge shaft  21 . The ceiling plate portion  32  extends forward from positions which are spaced a predetermined distance from the rear end portions of the right and left side walls  31 , while a space formed on the rear side of the ceiling plate portion  32  provides a base sheet discharge opening  33 . In the front side of the side wall portion  31 , which is the front end portion of the ceiling plate portion  32 , there is formed a label discharge opening  34 . On and from the rear side of the label discharge opening  34 , there is provided a lower guide  35  which inclines down forward. As shown in  FIGS. 3(   c ) and  3 ( d ), when the upper and lower covers  30  and  40  are closed, the base sheet discharge opening  33  of the upper cover  30  is covered with the base end portion  41  of the lower cover  40  with the front side portion thereof left uncovered, while the uncovered front side portion serves as the substantial base sheet discharge opening  33 . 
     As shown in  FIG. 2 , in the portion of the ceiling plate portion  32  that exists in front of the label discharge opening  34 , there is provided a front plate portion  36 . On the lower surface of the front portion of the front plate portion  36 , there is provided a projecting strip  37  which extends right and left in such a manner that it projects more downward as it goes more forward. Also, on the rear portion of the front plate portion  36 , there is provided an upper guide  38  which inclines in such a manner that the front thereof rises up backward. The upper guide  38  extends parallel to the lower guide  35  with a space between them. 
     The conveying direction of the label sheet  10  from the print mechanism  50  to the peel bar  60  extends along the direction of a tangent drawn from a contact point between the platen roller  51  and print head  52  to the outer peripheral surface of the front side of the peel bar  60 , that is, it extends substantially upward in the vertical direction. The upper guide  38  is disposed on the front side (print surface side) of the label  12  to be discharged to the label discharge opening  34  and is also projected backwardly of the conveying direction of the label sheet  10  extending substantially upward in the vertical direction just before the peel bar  60 , that is, it is projected toward the affixed surface side of the label  12  to the base sheet  11 . A space formed between the upper and lower guides  38  and  35  define a label discharge passage  70  which rises obliquely backward. 
     As shown in  FIG. 2 , on the upper surface of the front wall portion  20   a  of the casing  20 , namely, on the edge portion of the opening side of the casing  20 , there is formed a cutter portion  23  which rises up obliquely backward and has a triangular-shaped section, and the leading end portion of which is formed in an acute angle. The cutter portion  23  extends right and left and also has a width capable of cutting the label sheet  10 . When the upper cover  30  is closed, the rear end edge of the flat lower surface of the front plate portion  36  is situated just above the leading end of the cutter portion  23 , or is contacted with the leading end of the cutter  23 . Also, when the upper cover  30  is closed, the lower end of the projecting strip  37  of the front plate portion  36  is situated below the leading end of the cutter  23  and thus, between the front plate portion  36  and cutter portion  23 , there is formed a clearance the front of which lowers down. A space existing upward of the front wall portion  20   a , which extends from the leading end of the cutter portion  23  through the forward lowered upper surface of the cutter portion  23  to the front end of the front wall portion  20   a , provides a label sheet set passage  72 . 
     Also, downward of the lower guide  35 , there is disposed a peel roller  61  which extends parallel to the platen roller  51 . This peel roller  61  is rotatably supported between projecting portions  31   a  which are respectively provided on the front end portions of the right and left side wall portion  31 . When the upper and lower covers  30  and  40  are closed, the peel roller  61  is closely contacted with the platen roller  51  and is rotated by the platen roller  51  in such a manner that it follows the rotation of the platen roller  51 . The base sheet  11 , from which the label  12  has been peeled, is held by and between the platen roller  51  and peel roller  62  and, as the platen roller  51  rotates, the base sheet  11  is conveyed along a base sheet discharge passage  71  which extends from between the two rollers  51  and  61  through the upper surface of the lower cover  40  to the base sheet discharge opening  33 . 
     Also, at the position of the lower surface of the upper cover  40  that can be contacted with the rear end portion of the lower guide  35 , there is mounted a peel sensor  62  which detects a label  12  existing in the label discharge opening  34 . This peel sensor  62  is a sensor of a light reflection type which detects the existence of the label  12  in the label discharge opening  34 ; and, specifically, the peel sensor  62  detects that the label  12  has been correctly peeled from the base sheet  11  and also that the label  12  has been taken out by a user. 
     Further, on the portion of the inner surface of the front wall portion  20   a  of the casing  20  that exists downward of the print head  52 , there is mounted a label sensor  63 . This is a sensor of a light reflection type which detects, while the label sheet  10  is being conveyed, the conveying-direction leading end edge of the label  12  affixed to the base sheet  11  has reached the position of the label sensor  63 . 
     Now,  FIG. 4  shows the configuration of a control system which is incorporated into the label printer  1 , while the control of the conveying of the label sheet  10  and the printing onto the labels  12  is performed by a CPU  100 . To this CPU  100 , there are connected a ROM  101  for storing a control program and the like; a RAM  102  for storing print data received from an externally provided host computer, operation information about the operation of the label printer  1  when it is in operation and the like; and, an I/F (interface)  103  which is used to connect the label printer  1  to the host computer. 
     Further, to the CPU  100 , there are also connected the print head  51 , a conveying motor  53  for driving the platen roller  51 , a sheet feed switch  24 , the label sensor  63 , and the peel sensor  62  respectively through an input/output port  104 . The conveying motor  53  is stepping motor, which controls conveying quantity of the label sheet  10  corresponding to the number of stepping. 
     When the label sensor  63  detects the conveying direction leading end edge of the label  12 , it outputs an on signal to the CPU  100 ; and, when the peel sensor  62  detects that the label  12  exists in the label discharge opening  34 , outputs an on signal to the CPU  100 . These sensors  62  and  63  are respectively monitored by a program for their on/off states. The sheet teed switch  24  is disposed in the proper portion of the casing  20  such as the upper surface of the front wall portion  20   a  and, when the sheet feed switch  24  is turned on, the conveying motor  53  is rotated forward and the platen roller  51  is rotated in a direction to convey the label sheet  10 . 
     The configuration of the label printer  1  is as described above and, next, description will be given below of the method for using the label printer  1  and operations to be carried out by the above-mentioned control system. 
     (1) Setting of Label Sheet 
     Firstly, description will be given below of the procedure for setting the label sheet  10  with reference to  FIG. 3 . 
     As shown in  FIG. 3(   a ), the upper and lower covers  30  and  40  are opened, the core member  13  is arranged substantially parallel to the hinge shaft  21 , and the roll-shaped label sheet  10  is dropped down into the label sheet storage part  22  in an attitude where the end portion of the label sheet  10  disposed on the front side thereof is pulled upward from below. Next, the end portion of the label sheet  10  is pulled out to the outside of the casing  20  and, after then, as shown in  FIG. 3(   b ), the lower cover  40  is closed. The pulled-out label sheet  10  is held by and between the platen roller  51  and print head  52 . 
     Next, as shown in  FIG. 3(   c ), the base sheet  11  of the label sheet  10  is pressed against the peel bar  60  and is thereby turned back in the backward direction, the base sheet  11  is pulled out further to the outside through the base sheet discharge opening  33  of the upper cover  30 , and, as shown in  FIG. 3(   d ), the upper cover  30  is closed. When the upper cover  30  is closed, the label sheet  10  is held by and between the platen roller  51  and peel roller  61 . 
     (2) Operation of Label Printer 
     Now, Description Will be Given Below of the Operation to be carried out by the control system with reference to  FIG. 5 . 
     After the label sheet  10  is set in the above-mentioned manner, a user turns on the sheet feed switch  24  (Step S 101 ). When the platen roller  51  is rotated forward in the conveying direction by the conveying motor  53  and the conveying-direction leading end of the label  12  is detected for the first time by the label sensor  63  (Step S 102 ), the conveying motor  53  is rotated by a predetermined number of steps at and from the then time to convey the label sheet  10  by a length corresponding to [peel position+preliminary peel amount] (Step S 103 ). 
     Here, the term “peel position” means the position where the rear end edge of the label  12  existing one label downstream of the label  12  (the label on which printing is to be enforced from now) the leading end edge of which is detected by the label sensor  63  is fed to the downstream side of the peel bar  60  and the rear end edge of the label  12  is peeled from the base sheet  11 ; that is, the position where the whole of the label  12  is peeled. Also, the term “preliminary peel amount” means a length by which the leading end portion of the label  12  to be printed is fed to the downstream side of the peel bar  60 . While, in Step S 103 , the leading end portion of the label  12  to be printed is fed to the downstream side of the peel bar  60 , the leading end portion of such label  12  peels from the base sheet  11 , which is turned back by the peel bar  60  and is conveyed backward, due to its own rigidity, whereby there occurs a preliminary peel phenomenon in which only the leading end portion of such label  12  peels. A state in Step S 103  is shown in  FIG. 6(   a ). By the way, in  FIG. 6 , for simplification of the drawing, there are omitted the upper and lower guides  38  and  35 . 
     Next, it is checked whether the CPU  100  has received a print instruction from the host computer or not (Step S 104 ) and it is also checked whether a label  12  exists in the label discharge opening  34  or not (Step S 105 ). When it is found that the CPU  100  has received the print instruction but the peel sensor  62  detects that the label  12  does not exist in the label discharge opening  34  (a state where the peel sensor  62  is on), the platen roller  51  is rotated reversely, so that, as shown in  FIG. 6(   b ), there is performed an operation to find the beginning of the label  12  to be printed in which the leading end portion of the label  12  to be printed is made to correspond to the print head  52  (Step S 106 ). At the then time, the leading end portion of the preliminarily peeled label  12  is fed reversely more upstream than the peel bar  60  and is affixed again to the base sheet  11  but, since it is peeled off once due to the preliminary peeling operation, the adhesive power of the leading end portion of the label  12  to the base sheet  11  has weakened. 
     Next, based on the print data supplied, while rotating the platen roller  51  forward to convey the label sheet  10 , the label  12  is printed by the print head  51  (Step S 107 ).  FIG. 6(   c ) shows a state where the printing is being enforced. With execution of the operation to print the label  12  while conveying the label sheet  10 , the base sheet  11  just after the label  12  is printed is turned back in an acute angle by the peel bar  60 , whereby the label  12  is peeled from the base sheet  11 , passes through the upper label discharge passage  70  and goes out to the outside from the label discharge opening  34 . On the other hand, the base sheet  11  with the label  12  peeled therefrom is conveyed backward along the base sheet discharge passage  71  by the platen roller  51  and peel roller  61 , and the base sheet  11  shortly goes out to the outside from the base sheet discharge opening  33 . 
     Next, when it is found that the print data are terminated (Step S 108 ), the label sheet  10  is conveyed by a length [peel position+preliminary peel amount] in which the number of steps required for the printing is added (Step S 109 ). As a result of this, similarly to the state shown in  FIG. 6(   a ), the rear end (lower end) of the label  12  passes through the peel bar  60 , whereby the label  12  is peeled from the base sheet  11  completely and is then discharged from the label discharge opening  34 . On the other hand, the leading end portion of the label  12  to be printed next is fed to the downstream side of the peel bar  60 , and the above-mentioned preliminary peel state occurs in this label  12 . 
     And, the processing goes back to the step S 104 , where, in a state in which the preliminary peel state is held, the processing waits until it receives a next print instruction. After then, when not only the next print instruction is received but also the user takes away the discharged label  12  and the peel sensor  62  detects that the label  12  does not exists in the label discharge opening  34 , the next print is started. 
     The above-mentioned operations are carried out repeatedly, whereby the printing operation and peeling operation onto the labels  12  are carried out one after another. According to the present embodiment, when peeling the label  12  from the base sheet, firstly, prior to the printing operation to be performed onto the label  12 , only the leading end portion of the label  12  is fed once to the downstream side of the peel bar  60  including the bent portion of the conveying path to thereby peel the leading end portion preliminarily at the then time; and, next, the label sheet  10  is conveyed reversely to the upstream side and the printing operation is enforced onto the label  12 . Therefore, in the regular label peeling operation to be performed next while printing the label  12 , the label  12  can be securely peeled from the base sheet  12 . 
     And, without separately providing a device for peeling the label  12  preliminarily, the preliminary peel can be performed through the conveying operation of the label sheet  10 , which can avoid the inconvenience that the number of parts increases and the label printer increases in size. 
     By the way, according to the above embodiment, the preliminarily peeling operation for conveying the label sheet forwardly and reversely is performed once. However, the number of times of execution of the preliminarily peeling operation is not limited to one but such operation may be performed several times. The more the number of times of execution of the operation is, the more securely the preliminary peel can be attained even in the case of a label which is strong in the adhesive power thereof. 
     Also, instead of the forward and reverse conveying of the label sheet  10 , there can be employed a method in which, in a state where the leading end portion of the label  12  is fed to the downstream side of the peel bar  60 , the conveying of the label sheet  10  is stopped once and, after such state is held for a predetermined time, the conveying of the label sheet  10  is resumed. In this case, a printing operation is started in the state shown in  FIG. 6(   b ) where the beginning portion of the label  12  is found, as shown in  FIG. 6(   a ), at the time when the leading end portion of the label  12  reaches the downstream side of the peel bar  60 , the conveying of the label sheet  10  is stopped once and, after then, the printing operation is carried out while conveying the label sheet  10 . 
     In this manner, when the label sheet  10  is not reciprocated but the conveying of the label sheet  10  is stopped once and such stopping state is continued for a predetermined time, even in the case of a label which is difficult to peel, there can be produced a phenomenon that the leading end portion of the label gradually peels off from the base sheet  11 . Therefore, the preliminarily peeling operation of the label  12  and the regular peeling operation to be performed after then can be carried out securely. 
     Also, in the present label printer  1 , when the roll diameter of the label sheet  10  is relatively large and thus the curl of the label  12  is weak, as shown in  FIG. 1 , the label  12  is discharged substantially along the direction where the label discharge passage  70  extends. And, when the consumption of the label sheet  10  increases and thus the roll diameter thereof reduces, the degree of the curl of the label  12  to be discharged increases. Accordingly, as shown in  FIG. 7 , the printed surface of the label  12  is contacted with the upper guide  38  and thus the rear side of the label  12  relatively receives a pressing force from the upper guide  38 ; and, therefore, while the curl diameter of the label  12  is being forcibly increased, the label  12  passes through the label discharge passage  70 . 
     This can prevent the occurrence of the inconvenience that the label  12  can be curled excessively to thereby cause the back surface of the adhesive surface thereof to attach to the printed surface of the front surface thereof, or the label  12  can fall down to the outside from the label discharge opening  34 , whereby the label  12  can be made difficult to handle or cannot be used. Also, since the upper guide  38  is simply contacted with the printed surface of the label  12  to restrict the discharge direction of the label  12 , there is no fear that the printed surface of the label  12  can be damaged. 
     Further, because there is no possibility that the label  12  can be parted away from the peel sensor  62  too much due to the strong curl of the label  12 , the discharged label  12  can be detected securely by the peel sensor  62 . In this case, when the peel sensor  62  detects that the label  12  is not present in the label discharge opening  34 , a printing operation is started onto the next label  12 . This can give rise to the occurrence of the following malfunction. That is, when the label  12  parts away from the peel sensor  62  too much, although the label  12  is present in the label discharge opening  34 , it is judged that the label  12  is not present, so that the next printing operation is started. However, according to the present embodiment, such malfunction can be prevented. 
     Now, in the above-mentioned label printer  1 , the printed label  12  can also be discharged in a state where it is not peeled from the base sheet  11  but the label sheet  10  remains as it is. When using the label printer  1  in this manner, the label sheet  10  is set in the following manner. 
     As shown in  FIG. 8(   a ), similarly to the above-mentioned case, the label sheet  10  is dropped down into the label sheet storage part  22  provided within the casing  20 . Next, as shown in  FIG. 8(   b ), the label sheet  10  is pulled out and the excess end portion of the label sheet  10  is disposed so as to cover the upper surface of the front wall portion  20   a  of the casing  20 ; and, after then, the upper and lower covers  30  and  40  are closed. The excess end portion of the label sheet  10  is held by and between the upper surface of the front wall portion  20   a  of the casing  20  and the front plate portion  36  of the upper cover  30  and is disposed in the sheet set passage  72 . In this state, the excess end portion of the label sheet  10  is pulled out to the outside, and the label sheet  10  is held by and between the platen roller  51  and print head  52 . 
     Next, as shown in  FIG. 8(   c ), the excess end portion of the label sheet  10  coming out forward from between the front wall portion  20   a  of the casing  20  and the front plate portion  36  of the upper cover  30  is pulled forward. As a result of this, the label sheet  10  is cut by the leading end of the cutter portion  23 , whereby the excess end portion of the label sheet is removed. The cut end portion of the label sheet  10  with its excess end portion cut away, as shown by a two-dot chained line in  FIG. 2 , exists in the label discharge passage  70 . After then, a printing operation is performed onto the label  12 , and the label sheet  10 , as shown in  FIG. 8(   d ), is conveyed along the label discharge passage  70  and is discharged into the label discharge opening  34 . By the way, in this case, since the label  12  after printed is not peeled from the label sheet  10 , there is no need to perform the above-mentioned operation for attaining the preliminary peel state of the label  12 . And, there is employed a control method for continuously executing a printing operation on the labels  12  while conveying the label sheet  10 . 
     When the label  12  is discharged while it is not peeled from the label sheet  10  in this manner, at the stage where the excess end portion of the label sheet  10  is disposed in the label sheet set passage  72  and the label sheet  10  is cut by the cutter portion  23 , the conveying path of the label sheet  10  to be printed is automatically switched over to the label discharge passage  70 , thereby providing a label sheet setting state. Therefore, the switching of the label sheet passage can be carried out easily and securely. 
     Also, since the label sheet  10  is not conveyed reversely for the purpose of the switching of the passage, there is no possibility that the label sheet  10  can be deformed; for example, no wrinkles or bends can occur in the label sheet  10 . Especially, as in the present embodiment, in a case where there is used the label sheet  10  including the base sheet  11  and the labels  12  affixed to the base sheet  11 , when the label sheet  10  is conveyed reversely for a long distance, there is a fear that, for example, the rear end portion of the label  12  can reach the print head  52  and the print head  52  can peel the label  12  from the base sheet  11 , resulting in the bent label sheet  10 . However, because the label sheet  10  is not conveyed reversely, there is no possibility that such inconvenience can occur. 
     Also, since the label discharge passage  70  extends in the direction where the label sheet  10  is curled with respect to the label sheet set passage  72  (the direction where the rear of the label sheet  10  is inclined upwardly), when the label sheet  10  is cut, the leading end portion of the label sheet  10  is curled so that, as shown by a two-dot chained line in  FIG. 2 , it points to the same direction as the label discharge passage  70 . This makes it possible to securely guide the label sheet  10  from the label discharge passage  70  to the label discharge opening  34 . 
     Further, in the above-mentioned cutting operation, the cutter portion  23  projects upward and, on the other hand, the lower end of the projecting strip  37  of the upper cover  30  is situated downwardly of the leading end of the cutter portion  23  so that the excess end portion of the label sheet  10  is pressed downward, whereby the contact portion of the label sheet  10  with the leading end of the cutter portion  23  is bent at an acute angle. Thanks to this, when the excess end portion of the label sheet  10  is pulled forward, a stress, which the label sheet  10  receives from the leading end of the cutter portion  23 , concentrates on the contact portion of the label sheet  10 , thereby being able to cut the label sheet  10  easily. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  It is a section view of a label printer according to an embodiment of the invention. 
       FIG. 2  It is a partially enlarged view of the II portion shown in  FIG. 1 . 
       FIG. 3  It is a section view of a label printer according to the embodiment of the invention, showing the procedure for setting a label sheet in the label printer in the order of  FIGS. 3(   a ) to  3 ( d ). 
       FIG. 4  It is a block diagram of the configuration of a control system employed in a label printer according to the embodiment of the invention. 
       FIG. 5  It is a flow chart of the printing operation of a label printer according to the embodiment of the invention. 
       FIG. 6  It is a section view of a label printer according to the embodiment of the invention, showing the operation thereof for peeling a label preliminarily in the order of  FIGS. 6(   a ) to  6 ( c ). 
       FIG. 7  It is a section view of a label printer according to the embodiment of the invention, showing a case where the roll diameter of a label sheet is small. 
       FIG. 8  It is a section view of a label printer according to the embodiment of the invention, showing a label sheet setting procedure in the order of  FIGS. 8(   a ) to  8 ( d ) in a case where a label is not peeled. 
     
       
         
           
               
             
               
                   
               
               
                 Description of the Reference Numerals and Signs 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                  1: Label printer 
                 10: Label sheet 
               
               
                   
                  11: Base sheet 
                 12: Label 
               
            
           
           
               
               
            
               
                   
                  50: Print mechanism 
               
               
                   
                  60: Peel bar (peel mechanism, bent portion) 
               
               
                   
                  62: Peel sensor (label detect means) 
               
               
                   
                 100: CPU (control means)