Patent Publication Number: US-2019180265-A1

Title: Printer and merchandise information processing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 15/684,749, filed Aug. 23, 2017, which application is based upon and claims the benefit of priority from Japanese Patent Application No. 2016-170595, filed Sep. 1, 2016, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments described herein relate generally to a printer and a merchandise information processing apparatus. 
     BACKGROUND 
     A merchandise information processing apparatus (for example, a point of sales (POS) terminal) is usually equipped with a printer that prints information about, for example, transaction details on a receipt or journal. The printer prints the information on a sheet conveyed from, for example, a roll of paper, and then conveys the sheet having the information printed thereon to an outlet. 
     A printer is complicated in structure and is thus vulnerable to the occurrence of an abnormality, such as paper jam, during conveyance of sheets (hereinafter referred to as a “conveyance abnormality”). If the detection of the conveyance abnormality is late and the printer continues operating with the conveyance abnormality unresolved, the printer may fall into an irreparable condition. Therefore, it is desirable that the conveyance abnormality be detected in an early stage. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a merchandise information processing apparatus equipped with a printer according to an embodiment. 
         FIG. 2  is a perspective view of the printer. 
         FIG. 3  is a block diagram of the printer. 
         FIG. 4  is a functional block diagram of a control unit of the printer. 
         FIG. 5  is a diagram illustrating an internal structure of the printer. 
         FIG. 6  is an enlarged view of the vicinity of an outlet when a movable unit is in a protruding state. 
         FIG. 7A  is a diagram of a guide as viewed from a direction A 1  illustrated in  FIG. 6 . 
         FIG. 7B  is a diagram illustrating a modification example of the guide as viewed from the direction A 1 . 
         FIG. 8A  is a diagram of the guide as viewed from a direction A 2  illustrated in  FIG. 6 . 
         FIG. 8B  is a diagram of the guide as viewed from the direction A 2 , illustrating a condition in which the movable unit is located at the guide. 
         FIG. 9  is an enlarged view of the vicinity of the outlet when the movable unit is in a proximity state. 
         FIG. 10  is an enlarged view of the vicinity of the outlet when the movable unit is in a separation state. 
         FIG. 11  is a flowchart of a print processing. 
         FIG. 12  is an enlarged view of the vicinity of the outlet, illustrating a modification example of a location of the movable unit. 
         FIG. 13A  is a diagram of the guide as viewed from the direction A 2  illustrating the modification example of the location of the movable unit. 
         FIG. 13B  is a diagram of the guide as viewed from a direction A 2  illustrating a condition in which a sheet is situated between the movable unit and the guide. 
         FIG. 14  is an enlarged view of the vicinity of the outlet, illustrating another modification example of the movable unit. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments enable detecting of the conveyance abnormality of a sheet at an early stage. 
     A printer according to an embodiment includes a printing unit that prints on a sheet. The sheet is discharged through an outlet. The sheet is conveyed on a sheet conveyance path through the printing unit and to the outlet. A movable device is located on the sheet conveyance path upstream of the outlet in a sheet conveying direction. The movable device can move to a separation position in which the sheet causes the movable device to be separated, by more than a predetermined threshold distance, from a conveyance surface on a side of the sheet conveyance path opposite of the movable device. The movable device can move to a proximity position in which the sheet conveyed on the conveyance path causes the movable device to be within the predetermined threshold distance from the conveyance surface. The movable device can move to a protruding position in which a part of the movable device protrudes beyond the conveyance surface toward an opposite side thereof when the sheet is not conveyed on the conveyance path at the position of the movable device. A detection device detects a position of the movable device. A controller determines a conveyance abnormality of the sheet based on the state of the movable device detected by the detection device, and outputs a signal indicating the conveyance abnormality. 
     Hereinafter, illustrative embodiments will be described with reference to the drawings. Furthermore, in the drawings, the same or similar components are assigned the respective same reference characters. 
       FIG. 1  is a perspective view illustrating a merchandise information processing apparatus  1  equipped with a printer  10  according to an embodiment. The merchandise information processing apparatus  1  is, for example, a point of sales (POS) terminal. The merchandise information processing apparatus  1  is installed at each store and is operated by an operator. The merchandise information processing apparatus  1  is connected to a store server (POS server) (not illustrated) via a network. The printer  10  is connected to or incorporated in the merchandise information processing apparatus  1 . 
     Furthermore, in the following description, an orthogonal coordinate system with an X-axis, a Y-axis, and a Z-axis is used. In the reference coordinate axes, the direction indicated by an arrow is a positive direction. For example, in  FIG. 1 , the X-axis positive direction is the rightward direction, and the X-axis negative direction is the leftward direction. Moreover, the Y-axis positive direction is the rearward direction, and the Y-axis negative direction is the frontward direction (forward). Additionally, the Z-axis positive direction is the upward direction, and the Z-axis negative direction is the downward direction. The front refers to the side on which the operator is situated. In the example illustrated in  FIG. 1 , the frontward direction is a direction indicated by an unfilled arrow. 
       FIG. 2  illustrates the printer  10  separate from the merchandise information processing apparatus  1 . The printer  10  is a receipt printer used to issue a receipt. The printer  10  is equipped with a cover  19  at an upper portion thereof, and is able to load a roll of paper PR in the interior thereof. The roll of paper PR is a roll-shaped printing medium in which a sheet S is rolled. The printer  10  extracts the sheet S from the roll of paper PR and prints information about, for example, transaction details on the sheet S. The printer  10  includes an outlet  18  through which the sheet S is discharged. While, in the example illustrated in  FIG. 2 , the outlet  18  opens in the upward direction, the outlet  18  can also open in the frontward direction. Furthermore, the appearances illustrated in  FIG. 1  and  FIG. 2  are merely examples, and can be modified in various manners. 
       FIG. 3  is a block diagram of the printer  10 . The printer  10  includes a communication interface  11 , an output unit  12 , a control unit  13 , a printing unit  14 , a cutting unit  15 , and a conveyance abnormality detection unit  16 . 
     The communication interface  11  communicates with a control device (for example, a processor) of the merchandise information processing apparatus  1 . The communication interface  11  acquires various pieces of data from the merchandise information processing apparatus  1 . Data which the communication interface  11  acquires from the merchandise information processing apparatus  1  includes information which the printing unit  14  prints on the sheet S (for example, transaction details). Furthermore, in the following description, information which the printing unit  14  prints on a receipt is referred to as “print data”. 
     The output unit  12  is an output device used to inform the user of information. The output unit  12  is, for example, a sound-producing apparatus, such as a loudspeaker or a buzzer. The output unit  12  can also be a display device, such as a liquid crystal display or an organic electroluminescence (EL) display. The output unit  12  informs the user of the occurrence of an abnormality, such as the occurrence of a conveyance abnormality. 
     The control unit  13  is includes a processing device such as a processor. The control unit  13  functions as a control device that controls each unit of the printer  10 . The control unit  13  may have a single processor or a plurality of processors. In a case where the control unit  13  includes a plurality of processors, the plurality of processors may be arranged at different locations inside the printer  10  (for example, on different substrates). The control unit  13  operates according to a program stored in a read-only memory (ROM) or a random access memory (RAM) inside the control unit  13  or outside the control unit  13 , thus implementing various operations including reading processing, which is described below. Furthermore, the program may be a microprogram using microcode. 
       FIG. 4  is a functional block diagram of the control unit  13 . The control unit  13  may be programmed to function as a printing control unit  131 , a conveyance control unit  132 , a determination unit  133 , and an error output unit  134 . These functional blocks (the printing control unit  131 , the conveyance control unit  132 , the determination unit  133 , and the error output unit  134 ) can be software blocks or can be hardware blocks. For example, each block illustrated in  FIG. 4  can be a single piece of hardware (for example, a single processor or a single circuit block on a semiconductor chip). Further, each block can be implemented by a cooperation of a plurality of processors. Moreover, the control unit  13  may be configured with a single processor and each block may be implemented by software (including a microprogram). Even in a case where each block is implemented by software, the control unit  13  may be configured with a plurality of processors. The printing control unit  131  functions as a printing control unit of the printer  10 , and the conveyance control unit  132  functions as a conveyance control unit of the printer  10 . Moreover, the determination unit  133  functions as a determination unit of the printer  10 , and the error output unit  134  functions as an error output unit of the printer  10 . 
       FIG. 5  is a diagram illustrating an internal structure of the printer  10 . The printer  10  is configured to allow the roll of paper PR to be attached thereto and detached therefrom. The sheet S extracted from the roll of paper PR passes through conveyance paths T 1  to T 3  and is then discharged from the outlet  18 . The conveyance path T 1  is a pathway used until the sheet S arrives at the printing unit  14 . The printing unit  14  is located on the conveyance path T 2 . The conveyance path T 3  is a pathway between the printing unit  14  and the outlet  18 . The conveyance paths T 1  to T 3  can be pathways formed by sheet guides and rollers. In the printer  10 , the printing unit  14 , the cutting unit  15 , and the conveyance abnormality detection unit  16  are arranged along the conveyance paths. In the conveyance path T 3 , a guide  17  is positioned as a sheet guide that guides the sheet S to the outlet  18 . 
     The printing unit  14  prints various pieces of information, such as transaction details, on the sheet S. The printing unit  14  may be a thermal-type print unit. The printing unit  14  includes a print head  141  and a roller  142  (for both see  FIG. 6 ). The print head  141  is a thermal head, and the roller  142  is a platen roller. The roller  142  also serves as a conveyance unit that conveys the sheet S. The printing unit  14  prints information, such as transaction details, on the sheet S according to control performed by the control unit  13 . 
     The cutting unit  15  is a cutter used to cut off a printing-completed portion (for example, a portion serving as a receipt) from the sheet S. The cutting unit  15  can be a slide-type cutter or a roller-type cutter. In  FIG. 5 , a slide-type cutter is illustrated as an example of the cutting unit  15 . Naturally, the configuration of the cutting unit  15  is not limited to this, but can be modified in various manners. Furthermore, in  FIG. 5 , the cutting unit  15  is provided on the upstream side of the conveyance abnormality detection unit  16  (in other words, between the printing unit  14  and the conveyance abnormality detection unit  16 ); however, the cutting unit  15  may be provided on the downstream side of the conveyance abnormality detection unit  16  (in other words, between the conveyance abnormality detection unit  16  and the outlet  18 ). 
     The conveyance abnormality detection unit  16  is a detection device that detects whether a conveyance abnormality of the sheet S has occurred in the conveyance path T 3 . The conveyance abnormality detection unit  16  is a sensor that detects, for example, the presence or absence of the sheet S and the thickness of the sheet S in the conveyance path. Here, the conveyance abnormality refers to the sheet S not being conveyed in a normal way inside the conveyance path. The conveyance abnormality is typically paper jam, but is not limited to paper jam. The conveyance abnormality can include a case where the sheet S is unable to be conveyed due to, for example, runout of paper, wrinkles on paper, slack of paper, or failed loading of the roll of paper PR. The conveyance abnormality detection unit  16  is located between the printing unit  14  and the outlet  18  (in other words, in the conveyance path T 3 ). 
       FIG. 6  is an enlarged view of the vicinity of the conveyance abnormality detection unit  16  of the printer  10 . The conveyance abnormality detection unit  16  can be a mechanical sensor or can be an optical sensor. In  FIG. 6 , an actuator and sensor arrangement is illustrated as an example of the conveyance abnormality detection unit  16 . 
     The conveyance abnormality detection unit  16  includes a movable unit  161  and a detection unit  162 . The movable unit  161  is a movable device, such as a rotating body, which rotates around a rotating shaft  161   a . The axial direction of the rotating shaft  161   a  is a direction parallel to a conveyance surface P for the sheet S and perpendicular to the conveyance direction of the sheet S (in the case of the present embodiment, the X-axis direction). While, in the present embodiment, the movable unit  161  is a rotating body in the shape of a triangle plate, the configuration of the movable unit  161  is not limited to this. The movable unit  161  is located with one vertex of the triangle facing the conveyance path T 3 . 
     As mentioned above, the guide  17 , which guides the sheet S to the outlet  18 , is located in the conveyance path T 3 . The shape of the guide  17  can be optionally modified. In the present embodiment, as an example, the guide  17  is a plate-like sheet guide. The guide  17  is located in such a manner that a planar surface portion of the plate faces the sheet S. The movable unit  161  is located in such a way as to face the guide  17  across the conveyance surface P. Here, the conveyance surface P refers to a surface that guides the forward movement of the sheet S. 
       FIG. 7A  is a diagram illustrating the movable unit  161  and the guide  17  as viewed from a direction A 1  illustrated in  FIG. 6 . More specifically,  FIG. 7A  is a diagram illustrating the movable unit  161  and the guide  17  as viewed in the direction of the conveyance path T 3  from the position of the outlet  18  (in the case of the present embodiment, looking towards the Z-axis negative direction). In the guide  17 , a region used to face the sheet S (hereinafter referred to as a “guide region”) is formed as a planar surface portion. Therefore, in the example illustrated in  FIG. 7A , the planar surface portion of the guide  17  itself serves as the conveyance surface P. Furthermore, the guide region does not necessarily need to be a planar surface. For example, the guide region can be in the shape of a patterned raised and recessed surface as illustrated in  FIG. 7B . In this case, a surface formed by connecting protruding portions (points, lines, or surfaces) facing the sheet S serves as the conveyance surface P. The conveyance surface P is not limited to a planar surface, but can be a curved surface. 
       FIG. 8A  is a diagram illustrating the guide  17  as viewed from a direction A 2  illustrated in  FIG. 6 . More specifically,  FIG. 8A  is a diagram illustrating the guide  17  as viewed in the horizontal direction from the front side of the printer  10 . An insertion receiving portion  17   a , into which a part of the movable unit  161  may be inserted, is formed at the guide region of the guide  17 . The insertion receiving portion  17   a  maybe a through-hole or a recessed portion. The movable unit  161  is located at a position opposite to the insertion receiving portion  17   a  as illustrated in  FIG. 8B . 
     As mentioned above, the movable unit  161  rotates around the rotating shaft  161   a . When rotating around the rotating shaft  161   a , the movable unit  161  reciprocates in a direction to separate from the conveyance surface P (in the case of the example illustrated in  FIG. 6 , the Y-axis negative direction) and a direction towards the conveyance surface P (in the case of the example illustrated in  FIG. 6 , the Y-axis positive direction). An urging force is applied to the movable unit  161  in a direction towards the guide  17 . Referring to the example illustrated in  FIG. 6 , an urging force is applied to the movable unit  161  so that the movable unit  161  rotates clockwise, in  FIG. 6 , around the rotating shaft  161   a . The urging force can be a spring force or can be a magnetic force. 
     During non-passage of the sheet S, the urging force causes a part of the movable unit  161  to protrude beyond the conveyance surface P toward the opposite side thereof (the Y-axis positive direction side) as illustrated in  FIG. 7A . Furthermore, in the following description, such a protruding portion ( 161   b  illustrated in  FIG. 7A ) is referred to as a “protrusion”. Moreover, in the following description, a state in which the protrusion  161   b  is protruding is referred to as a “protruding state”, and a state in which the protrusion  161   b  is not protruding is referred to as a “non-protruding state”. 
       FIG. 9  illustrates a state of the movable unit  161  taken when the sheet S is situated between the movable unit  161  and the conveyance surface P, in a normal state. The normal state refers to a state in which the sheet S is being conveyed through the conveyance path without any conveyance abnormality, such as paper jam. When the sheet S passes between the movable unit  161  and the conveyance surface P, the movable unit  161  is pushed by the sheet S to rotate counterclockwise, in  FIG. 9 , around the rotating shaft  161   a  by an angle r 1 . With this, the protrusion  161   b  of the movable unit  161  enters a state in which the protrusion  161   b  is in proximity to the conveyance surface P. In the following description, the state in which the protrusion  161   b  is in proximity to the conveyance surface P is referred to as a “proximity state”. The proximity state is one of non-protruding states. Furthermore, even a state in which the protrusion  161   b  is somewhat protruding from the conveyance surface P due to flexure of the sheet S can be regarded as a state in which the movable unit  161  is in the non-protruding state (and the proximity state). Moreover, even a state in which the protrusion  161   b  is somewhat separate from the conveyance surface P due to the thickness or small wrinkles of the sheet S can be regarded as a state in which the movable unit  161  is in the proximity state. 
       FIG. 10  illustrates a state of the movable unit  161  taken when the sheet S is situated between the movable unit  161  and the conveyance surface P in a paper jam state. The sheet S jammed in the vicinity of the outlet  18 . In this case, the movable unit  161  is pushed by the sheet S to rotate counterclockwise, in  FIG. 10 , around the rotating shaft  161   a  by an angle r 2 . The angle r 2  is greater than the angle r 1 . Accordingly, the protrusion  161   b  of the movable unit  161  enters a state in which the protrusion  161   b  is separate from the conveyance surface P. In the following description, the state in which the protrusion  161   b  is separate from the conveyance surface P is referred to as a “separation state”. The separation state is one of non-protruding states. The position of the movable unit  161  in the protruding state may be referred to as a protruding position. Further, he position of the movable unit  161  in the proximity state may be referred to as a proximity position. Further, the position of the movable unit  161  in the separation state may be referred to as a separation position. 
     What state of the movable unit  161  is deemed as the protruding state, the proximity state, or the separation state can be set by the apparatus designer as appropriate. For example, in a case where the distance from the conveyance surface P to a tip of the protrusion  161   b  (hereinafter referred to as a “separation amount d”) falls within a predetermined range (for example, in a case where the tip of the protrusion  161   b  is present in a range D 1  illustrated in  FIG. 10 ), the movable unit  161  is determined to be in the proximity state. Moreover, in a case where the separation amount d exceeds a predetermined amount toward the non-protruding side (the Y-axis negative direction side) (for example, in a case where the tip of the protrusion  161   b  is present in a range D 2  illustrated in  FIG. 10 ), the movable unit  161  is determined to be in the separation state. Additionally, in a case where the separation amount d exceeds a predetermined amount toward the protruding side (the Y-axis positive direction side) (for example, in a case where the tip of the protrusion  161   b  is present in a range D 3  illustrated in  FIG. 10 ), the movable unit  161  is determined to be in the protruding state. The separation amount (threshold value), which is used to distinguish between the protruding state, the proximity state, and the separation state, can be set as appropriate by the apparatus designer. 
     The detection unit  162  is a detection device such as a sensor that detects the state of the movable unit  161 . The detection unit  162  is, for example, a photosensor. In  FIG. 6 ,  FIG. 9 , and  FIG. 10 , a rod-like sensor having a plurality of sensors (filled circles in these figures) is illustrated as an example of the detection unit  162 . The plurality of sensors is arranged along the rotational direction of the movable unit  161 . Each of the plurality of sensors is able to detect light. A light source (not illustrated) is located at the opposite side of the plurality of sensors across the movable unit  161 . The detection unit  162  detects the state of the movable unit  161  according to whether light is blocked by the movable unit  161 . Furthermore, the configuration of the detection unit  162  as described herein is merely an example. Various known configurations can be employed as the detection unit  162  so long as it is able to detect the state of the movable unit  161 . 
     The state of the movable unit  161  which the detection unit  162  detects can be digital information indicating in which state the movable unit  161  is out of the protruding state, the proximity state, and the separation state, or can be analog information indicating the separation amount of the protrusion  161   b  from the conveyance surface P. A detection result obtained by the detection unit  162  is sent to the control unit  13 . The detection result can be an electrical signal (for example, a voltage level indicating the state or separation amount of the movable unit  161 ), or can be a data signal (for example, a numerical value indicating the state or separation amount of the movable unit  161 ). The detection unit  162  functions as a detection unit of the printer  10 . Each of the plurality of sensors included in the detection unit  162  can be regarded as a detection unit. 
     Next, an operation of the printer  10  having the above-described configuration is described. 
     The control unit  13  of the printer  10  starts print processing in response to receiving a printing start instruction from the merchandise information processing apparatus  1 . Hereinafter, the print processing is described with reference to the flowchart of  FIG. 11 . 
     In step ACT 101 , the determination unit  133  of the control unit  13  determines whether the movable unit  161  is in the separation state, such as that illustrated in  FIG. 10 . The determination unit  133  detects the state of the movable unit  161  based on the detection result sent from the detection unit  162 . 
     If the movable unit  161  is in the separation state (YES in step ACT 101 ), the determination unit  133  determines that the conveyance abnormality of the sheet S is occurring between the printing unit  14  and the outlet  18  (in the conveyance path T 3 ), and then proceeds to step ACT 108 . In step ACT 108 , the error output unit  134  outputs to the output unit  12  information indicating that the conveyance abnormality is occurring in the conveyance path T 3 . The error output unit  134  can output such error information to the merchandise information processing apparatus  1  via the communication interface  11 . Furthermore, in a case where the conveyance of the sheet S is previously started, then in step ACT 109 , the conveyance control unit  132  stops the conveyance of the sheet S. 
     If the movable unit  161  is not in the separation state (NO in step ACT 101 ), then in step ACT 102 , the determination unit  133  determines whether the movable unit  161  is in the proximity state, such as that illustrated in  FIG. 9 . As with step ACT 101 , the determination unit  133  detects the state of the movable unit  161  based on the detection result sent from the detection unit  162 . If the movable unit  161  is in the proximity state (YES in step ACT 102 ), since the sheet S is in the normal state, the determination unit  133  proceeds to execution of printing in step ACT 105 . 
     If the movable unit  161  is not in the proximity state (NO in step ACT 102 ), since the sheet S is not present between the movable unit  161  and the conveyance surface P, the determination unit  133  is unable to determine whether the sheet S is in the normal state. Therefore, in step ACT 103 , the conveyance control unit  132  performs the conveyance of the sheet S to bring the sheet S to a space between the movable unit  161  and the conveyance surface P. In such an arrangement, the conveyance control unit  132  controls the roller  142  to convey the sheet S. In a case where the printer  10  has a conveyance roller separately from the roller  142 , the conveyance control unit  132  can control the conveyance roller to convey the sheet S. In such an arrangement, the printing control unit  131  can control the print head  141  to start printing at the same time as the start of conveyance. 
     Then, in step ACT 104 , the determination unit  133  determines whether the movable unit  161  enters the proximity state within a previously-set time from the start of conveyance. As with step ACT 101 , the determination unit  133  detects the state of the movable unit  161  based on the detection result sent from the detection unit  162 . 
     If the movable unit  161  does not enter the proximity state (NO in step ACT 104 ), the determination unit  133  determines that the conveyance abnormality is occurring at the printing unit  14  (in the conveyance path T 2  illustrated in  FIG. 5 ) or before the sheet S arrives at the printing unit  14  (in the conveyance path T 1  illustrated in  FIG. 5 ), and then proceeds to step ACT 108 . In step ACT 108 , the error output unit  134  outputs, to the user via the communication interface  11  or the output unit  12 , information indicating that the conveyance abnormality is occurring in the conveyance path T 1  or T 2 . Then, in step ACT 109 , the conveyance control unit  132  stops the conveyance of the sheet S. In order to reduce the expansion of the abnormality, the conveyance control unit  132  can stop the conveyance before the error output unit  134  outputs such error information. 
     Furthermore, in a case where the movable unit  161  enters the separation state within a previously-set time from the start of conveyance, the determination unit  133  determines that the conveyance abnormality is occurring in the conveyance path T 1 . In this case, the error output unit  134  also outputs information indicating that the conveyance abnormality is occurring in the conveyance path T 1  or T 2 , and at the same time, the conveyance control unit  132  stops the conveyance of the sheet S. 
     If the movable unit  161  enters the proximity state (YES in step ACT 104 ), since the sheet S is in the normal state, the printing control unit  131  prints print data on the sheet S. In step ACT 105 , coordinating with printing performed by the printing control unit  131 , the conveyance control unit  132  conveys the sheet S. 
     Then, in step ACT 106 , the determination unit  133  determines whether the movable unit  161  is in the proximity state. As with step ACT 101 , the determination unit  133  detects the state of the movable unit  161  based on the detection result sent from the detection unit  162 . 
     If the movable unit  161  is not in the proximity state, in other words, if the movable unit  161  is in the protruding state or the separation state (NO in step ACT 106 ), the determination unit  133  determines that the conveyance abnormality is occurring during printing. More specifically, if the movable unit  161  enters or remains in the protruding state after starting conveyance, the determination unit  133  determines that runout of paper has occurred or the conveyance abnormality is occurring in the conveyance path T 1  or T 2 . Moreover, if the movable unit  161  enters the separation state, the determination unit  133  determines that the conveyance abnormality is occurring in the conveyance path T 3 . In step ACT 108 , the error output unit  134  outputs information indicating the occurrence of the conveyance abnormality. Then, in step ACT 109 , the conveyance control unit  132  stops the conveyance of the sheet S. The conveyance control unit  132  can stop the conveyance before the error output unit  134  outputs such error information. 
     If the movable unit  161  is in the proximity state (YES in step ACT 106 ), then in step ACT 107 , the determination unit  133  determines whether printing is completed. If printing is not completed (NO in step ACT 107 ), the control unit  13  returns to step ACT 105 . If printing is completed (YES in step ACT 107 ), then in step ACT 109 , the conveyance control unit  132  stops the conveyance of the sheet S. When the conveyance is stopped, the control unit  13  ends the print processing. 
     According to the present embodiment, since the printer  10  is equipped with the movable unit  161 , the detection unit  162 , and the determination unit  133 , the user can be notified of the conveyance abnormality of the sheet S at an early stage. In particular, the movable unit  161  is not provided inside a complicated mechanism of the printer  10  (for example, the conveyance path T 1  or T 2 ) but rather in the vicinity of the outlet  18  of the printer  10 . Therefore, the movable unit  161  is unlikely to hinder the conveyance of the sheet S, and the movable unit  161  is unlikely to cause the conveyance abnormality of the sheet S. 
     Furthermore, the movable unit  161  is able to move between the protruding state and the proximity state. Therefore, even if the movable unit  161  is not provided at a deep position inside the mechanism, the printer  10  is able to determine whether the conveyance abnormality is occurring inside the mechanism by checking whether the movable unit  161  changes into the proximity state after the start of printing. 
     The above-described embodiment is merely an example, and can be modified in various manners and applied to various usages. 
     For example, in the above-described embodiment, the movable unit  161  is located at the side of the conveyance surface P closer to the print head  141  (at the Y-axis negative direction side). In other words, the movable unit  161  is located in such a way as to face a printing surface of the sheet S. However, the movable unit  161  can be located in such a way as to face a non-printing surface of the sheet S. The non-printing surface is a surface of the sheet S on which printing is not performed. 
       FIG. 12  illustrates an example in which the movable unit  161  is located in such a way as to face the non-printing surface of the sheet S. In the example illustrated in  FIG. 12 , the movable unit  161  is located at the side of the conveyance surface P closer to the roller  142  (at the Y-axis positive direction side) in such a manner that the movable unit  161  faces a non-printing surface of the sheet S. With this, since the movable unit  161  no longer contacts a recording region of the sheet S, characters printed on the sheet S are unlikely to become illegible due to, for example, friction or pressure from the movable unit  161 . For example, in a case where the sheet S is thermal paper, a phenomenon in which a line appears in a printing region due to a pressure from the movable unit  161  can be reduced. The recording region refers to a region excluding the left, right, top, and bottom margin regions in the printing surface of the sheet S. In an example illustrated in  FIG. 13B , the recording region is a region RA surrounded by a dashed line in a central portion of the sheet S. 
     Furthermore, the movable unit  161  can be located in such a way as to face a non-recording region of the printing surface. For example, as illustrated in  FIGS. 13A and 13B , the movable unit  161  can be located at the end of the guide  17  in the X-axis direction in such a way as to face a right margin region M R  or left margin region M L  of the sheet S. Moreover, while, in the example illustrated in  FIGS. 13A and 13B , the movable unit  161  is located in such a way as to face the margin region M R , the movable unit  161  can be located in such a way as to face the margin region M L . Additionally, the non-recording region refers to a region excluding the recording region RA in the surfaces of the sheet S. More specifically, the non-recording region refers to a non-printing surface and left, right, top, and bottom margin regions of a printing surface of the sheet S. 
     Furthermore, while, in the above-described embodiment, the movable unit  161  is a rotating body, the movable unit  161  is not limited to this. For example, as illustrated in  FIG. 14 , the movable unit  161  can be a rod-like body, which is inserted into a tubular support member  161   c  and is linearly movable along the direction generally perpendicular to (or at least away from) the conveyance surface P (the Y-axis direction). In such an arrangement, the detection unit  162  can be configured with a plurality of photosensors each of which detects the state of the movable unit  161  according to whether light is blocked by the rod-like body. 
     The insertion receiving portion  17   a , into which the protrusion  161   b  of the movable unit  161  is inserted, is a through-hole or a recessed portion. However, the insertion receiving portion  17   a  is not limited to these. For example, the insertion receiving portion  17   a  can be a gap between the guide  17  and a chassis of the printer  10 . Additionally, the guide  17  may be configured with a plurality of members, and the insertion receiving portion  17   a  can be a gap between a member and another member. 
     Furthermore, while, in the above-described embodiment, the movable unit  161  takes three states, i.e., the protruding state, the proximity state, and the separation state, the states which the movable unit  161  takes can be two states out of these states. For example, the movable unit  161  can be configured to take the proximity state and the separation state, or the protruding state and the proximity state. Moreover, while, in the above-described embodiment, the non-protruding state which the movable unit  161  takes includes two states, the separation state and the proximity state, the non-protruding state can be any one of the separation state and the proximity state. 
     Furthermore, while, in the above-described embodiment, the printing unit  14  is a thermal-type print unit, the printing unit  14  is not limited to the thermal-type print unit. For example, the printing unit  14  can be a dot impact-type, inkjet-type, or electrophotographic-type print unit. 
     Moreover, while, in the above-described embodiment, the printer  10  is connected to or incorporated in the merchandise information processing apparatus  1 , the printer  10  can be configured to be externally attachable to the merchandise information processing apparatus  1 . For example, the printer  10  can be equipped with a connection interface, such as Universal Serial Bus (USB), and can be configured to be connectable to the merchandise information processing apparatus  1  via a communication cable, such as a USB cable. 
     Besides, the printer  10  can be equipped with a user interface and can be configured to be able to operate independently of the merchandise information processing apparatus  1 . Additionally, the printer  10  can be connected to a personal computer and can be configured to operate based on a instruction from the personal computer. 
     Furthermore, while, in the above-described embodiment, the printer  10  is equipped with the output unit  12 , the printer  10  does not need to be equipped with the output unit  12 . In such an arrangement, the error output unit  134  of the control unit  13  only needs to inform the merchandise information processing apparatus  1  (or another apparatus) of the occurrence of the conveyance abnormality via the communication interface  11 . 
     Moreover, in the above-described embodiment, the merchandise information processing apparatus  1  has a configuration to which the printer  10  is fixed or in which the printer  10  is incorporated. However, the merchandise information processing apparatus  1  can be configured to be able to directly perform printing on the sheet S without involving the printer  10 . For example, the merchandise information processing apparatus  1  can include the communication interface  11 , the output unit  12 , the control unit  13 , the printing unit  14 , the cutting unit  15 , the conveyance abnormality detection unit  16  (the movable unit  161  and the detection unit  162 ), and the guide  17 . The control unit  13  can be used in common with a control device (for example, a processor) which controls each unit of the merchandise information processing apparatus  1 . The merchandise information processing apparatus  1  can be regarded as the printer  10  itself. 
     Furthermore, while, in the above-described embodiment, the merchandise information processing apparatus  1  is a POS terminal, the merchandise information processing apparatus  1  is not limited to the POS terminal. For example, the merchandise information processing apparatus  1  can be a stand-alone type cash register which does not have a network connection function. 
     Moreover, while, in the above-described embodiment, the printer  10  is installed at a POS terminal or a stand-alone type cash register, the apparatus at which the printer  10  is installed can be another apparatus, such as an automated teller machine (ATM) or an automatic vending machine. 
     Additionally, while, in the description of the above-described embodiment, the printer  10  is a receipt printer, the printer  10  is not limited to the receipt printer. For example, the printer  10  can be a label printer. In such an arrangement, a roll of paper PR to be stored in the printer  10  can be a roll of paper for label printing in which a label printing sheet is rolled. Naturally, the printer  10  can be a printer other than the receipt printer and the label printer. For example, the printer  10  can be a printer that performs printing on a list of particulars (for example, a bank statement). Moreover, a printing medium on which the printer  10  performs printing is not limited to a continuous sheet such as a roll of paper. For example, the printer  10  can be a printer that performs printing on a non-continuous profile sheet, such as plain paper (for example, A 4  size paper or B 5  size paper). The non-continuous profile sheet can be photo paper. 
     A control device that controls the printer  10  or the merchandise information processing apparatus  1  according to the present embodiment can be implemented by a dedicated computer system or can be implemented by an ordinary computer system. For example, the control device can be configured by storing a program for performing the above-described operation in a computer-readable recording medium, such as an optical disc, a semiconductor memory, a magnetic tape, or a flexible disc, distributing the computer-readable recording medium, installing the program on a computer, and performing the above-described processing. In such an arrangement, the control device can be a computer (processor) incorporated in the printer  10  or the merchandise information processing apparatus  1  or can be a computer which externally controls the printer  10  or the merchandise information processing apparatus  1 . Furthermore, the above-mentioned program can be previously stored in a disk device included in a server apparatus on a network such as the Internet and can be allowed to be, for example, downloaded to a computer. Moreover, the above-described functions can be implemented by a cooperation between an operating system (OS) and application software. In this case, a program other than the OS can be previously stored in a medium and the medium can be distributed, or a portion other than the OS can be previously stored in a server apparatus and can be allowed to be, for example, downloaded to a computer. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.