Patent Publication Number: US-2012034010-A1

Title: Printer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2010-177247, filed on Aug. 6, 2010, the entire content of which is incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a printer. 
     BACKGROUND 
     In the related art, there is known a printer which includes a transport roller and a pinch roller, each of which is disposed at the upstream side of a platen roller in a paper feeding direction. A paper is interposed between the transport roller and the pinch roller to be conveyed along the paper feeding direction. 
     Such a printer requires a mechanism to avoid the occurrence of for example, malfunction of the printer, paper slippage, paper jam or the like to provide a stable paper conveyance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a printer configuration according to an illustrative embodiment. 
         FIG. 2  is a perspective view showing a pinch roller block and a print block of a printer according to an illustrative embodiment. 
         FIG. 3  is another perspective view of the pinch roller block and the print block of the printer, as seen in a different view from that of  FIG. 2 . 
         FIG. 4  is a front view of a transport roller, a pinch roller and a torque transmitting mechanism of a printer according to an illustrative embodiment. 
         FIG. 5A  is a side view showing a state in which teeth of a driving gear are relatively deeply engaged with those of a driven gear according to an illustrative embodiment. 
         FIG. 5B  is a side view showing a state in which teeth of a driving gear are relatively slightly engaged with those of a driven gear according to an illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a printer includes a platen roller configured to be rotary-driven by a rotary drive source, and a transport roller provided at the upstream side of the platen roller in a paper feeding direction. The transport roller is configured to be rotary-driven by the rotary drive source. The printer further includes a pinch roller configured to be elastically urged against the transport roller. The pinch roller is configured to be rotary-driven by the rotary drive source. 
     Embodiments will now be described in detail with reference to the drawings. 
     As shown in  FIG. 1 , a printer  1  of an illustrative embodiment may print on a label (used as a printing medium) provided (e.g., adhered to) on an inner surface  2   a  of a strip-shaped material  2  (e.g., paper). In some embodiments, the printer  1  may print on a printing medium other than a label, for example, a continuous-form paper without a backing sheet. In addition, the printer  1  may have a function of writing and reading data to and from an RFID (Radio Frequency IDentification) chip provided on a label. 
     As shown in  FIG. 1 , a main body  1   a  of the printer  1  may include a housing  1   b  having a bottom wall  1   c  and a side wall. The housing lb includes a longitudinal wall ld provided perpendicular to the bottom wall  1   c  and also parallel to the side wall. On the longitudinal wall  1   d , a roll holding shaft  3 , a transport roller  4 , a platen roller  5 , a supply shaft  7  for an ink ribbon  6 , a take-up shaft  8  for the ink ribbon  6 , a print block  9 , a pinch roller block  10  and the like are disposed perpendicular to the longitudinal wall  1   d . A control circuit may be provided on the rear side of the longitudinal wall  1   d  in the housing  1   b , as seen from a front side of the plane view of  FIG. 1 . 
     The roll holding shaft  3  may rotatably hold a roll (e.g., paper roll)  11 , around which the strip-shaped paper  2  is wound, in a state perpendicular to the plane of  FIG. 1 . In one embodiment, the roll holding shaft  3  may be rotatably supported by the longitudinal wall  1   d . Alternatively, the roll holding shaft  3  may be fixed on the longitudinal wall ld, thereby allowing the paper roll  11  wound with the strip-shaped paper  2  to rotate around the roll holding shaft  3 . In any of the above embodiments, the roll holding shaft  3  and the paper roll  11  are not driven by, for example, a motor. The paper roll  11  wound with the strip-shaped paper  2  rotates (or is driven) in conjunction with the rotation of the transport roller  4  and the platen roller  5 , which are provided at the downstream side of the paper roll  11  in a paper feeding direction TD (e.g., the left direction in  FIG. 1 ). As a result, the strip-shaped paper  2  is discharged from the paper roll  11 . 
     In the above embodiment, the transport roller  4 , the platen roller  5  and a pinch roller  20  (see  FIG. 4 ) may be rotary-driven by means of a rotary drive source (e.g., a motor  14  as shown in  FIG. 2 ) through a torque transmitting mechanism. The transport roller  4  is provided at the upstream side of a print unit  12  and the platen roller  5  in the paper feeding direction TD. The pinch roller  20  is disposed in parallel and vertically adjacent to the transport roller  4 , along the paper feeding direction TD. The pinch roller  20  is urged against the transport roller  4  with a predetermined pressure. The strip-shaped paper  2 , interposed between the transport roller  4  and the pinch roller  20 , is conveyed in the paper feeding direction TD in conjunction with the rotation of the transport roller  4  and the pinch roller  20 . In this embodiment, the transport roller  4 , the pinch roller  20 , the platen roller  5 , the motor  14 , and a motor controller may constitute a conveying mechanism. 
     A ribbon roll  13 , around which a strip-shaped material (e.g., ink ribbon  6 ) is wound, is held by the supply shaft  7  for the ink ribbon  6 . The take-up shaft  8  may be rotary-driven by means of, for example, the motor  14 . With the rotation of the take-up shaft  8 , the ink ribbon  6  is discharged from the ribbon roll  13  and wound around the take-up shaft  8 . Both the ink ribbon  6  and the strip-shaped paper  2  are interposed between a thermal head  9   a  included in the print block  9  and the platen roller  5 . The thermal head  9   a  generates heat, which allows ink on the ink ribbon  6  to melt or sublimate. Through such operation of the thermal head  9   a , a predetermined pattern such as a character, numeric character, bar code, or graphic, is transferred onto a label which is provided (e.g., attached) on a surface of the strip-shaped paper  2  (e.g., the inner surface  2   a ). In this embodiment, a print mechanism may include the ink ribbon  6 , the supply shaft  7 , the take-up shaft  8 , the print block  9 , the thermal head  9   a , the motor  14 , and the motor controller. The print unit  12  may include the thermal head  9   a  and the platen roller  5 . A rewinder  21  may be provided to rewind a backing sheet that is detached from the strip-shaped material  2  being discharged from the paper roll  11 . The rewinder  21  may be rotary-driven by the motor  14 . 
     As stated above, the strip-shaped paper  2  is interposed between the transport roller  4  and the pinch roller  20 , each of which is provided at the upstream side of the platen roller  5  in the paper feeding direction TD. According to the embodiment described above, the pinch roller  20  in addition to the transport roller  4  may be rotary-driven. In an arrangement of the related art, a pinch roller is disposed opposite a transport roller (with a paper interposed between the pinch roller and the transport roller) and is urged elastically against the transport roller, but it is not rotary-driven. That is, the pinch roller is driven in response to the discharge of the paper from a roll wound with the paper. Such an arrangement requires an increased urging force of the pinch roller against the transport roller so as to stably convey the paper interposed between the pinch roller and the transport roller. Unfortunately, the increased urging force causes an excessive gripping force applied to the paper by the pinch roller and the transport roller. As a result, a paper crease is prone to occur at the point of gripping, or a motor load required for the paper conveyance may increase significantly. In one embodiment according to the present disclosure, both the transport roller  4  and pinch roller  20  rotate in combination such that the urging force of the pinch roller  20  against the transport roller  4  is reduced compared to the pinch roller in the related art that does not rotate. Further, this reduces the above-described problems associated with the increased urging force. 
     As shown in  FIG. 2 , in one embodiment, when the motor  14  is energized, a torque (e.g., a rotational force) produced by the rotation of an output shaft of the motor  14  is transmitted to the transport roller  4  and the platen roller  5  by means of a first torque transmitting mechanism  15 . The first torque transmitting mechanism  15  may include two sub-mechanisms corresponding to respective rollers (e.g., the transport roller  4  and the platen roller  5 ), each of which includes a driving pulley, an endless belt  15   a , a driven pulley  15   b , a driving gear  15   c , and a driven gear  15   d . The two driving pulleys are disposed in parallel with the axial direction of the output shaft of the motor  14 . The two driven pulleys  15   b  are spaced apart from each other in the paper feeding direction TD. The endless belts  15   a  are stretched over the driving pulley and the driven pulley  15   b  for the transport roller  4 , and over the driving pulley and the driven pulley  15   b  for the platen roller  5 , respectively. The driving gears  15   c  are arranged to connect to the respective driven pulleys  15   b  and are engaged with the respective driven gears  15   d . One of the two driven gears  15   d , which is disposed at a more upstream side in the paper feeding direction TD, is arranged to connect to the transport roller  4 . The other driven gear  15   d , which is disposed at a more downstream side in the paper feeding direction TD, is arranged to connect to the platen roller  5 . In this arrangement, a torque produced by the rotation of the output shaft of the motor  14  is transmitted to the transport roller  4  and the platen roller  5 , through the two sub-mechanisms each formed by the driving pulley, the endless belt  15   a , the driven pulley  15   b , the driving gear  15   c , and the driven gear  15   d.    
     As shown in  FIGS. 2 and 3 , in one embodiment, the rotational force of the transport roller  4  is transmitted to the pinch roller  20  by means of a second torque transmitting mechanism  16 , which includes a driving gear  16   a  and a driven gear  16   b . The driving gear  16   a  is configured to connect to one end of the transport roller  4 , and the driven gear  16   b , which is engaged with the driving gear  16   a , is configured to connect to one end of the pinch roller  20 . Thus, the rotational force of the transport roller  4  can be transmitted to the pinch roller  20  through the driving gear  16   a  and the driven gear  16   b.    
     The pinch roller  20  is rotatably supported by a pinch roller supporting member  18 . The pinch roller supporting member  18  includes a main body  18   b , which rotatably supports the pinch roller  20  and includes protrusions (e.g., provided in the opposite direction to the pinch roller  20 ) on the upper side of both ends of the pinch roller supporting member  18  in a widthwise direction WD of the strip-shaped paper  2 . The pinch roller supporting member  18  further includes a pair of brackets  18   a  which are fixed on top of the main body  18   b  and at both sides of the pinch roller supporting member  18 . A plate spring  17   c  is configured to connect to the pair of brackets  18   a  at both sides thereof. The pinch roller supporting member  18  further includes a pair of guiding members  18   c  (see  FIG. 3 ) formed on a side plate  10   a  of the pinch roller block  10 , each of which is vertically movable along a path defined by a vertically-elongated guide slot  10   b . As such, the pinch roller supporting member  18  and the pinch roller  20  are supported by the pinch roller block  10  to vertically move along the path defined on the side plate  10   a  of the pinch roller block  10 . 
     The pinch roller supporting member  18  is elastically urged against the transport roller  4  by means of an urging member  17 . The urging member  17  includes a cam shaft  17   a , a cam  17   b , the plate spring  17   c , and a coil spring  17   d . The cam shaft  17   a  extends in the widthwise direction WD and is rotatably supported by the side plate  10   a  of the pinch roller block  10 . The cam  17   b  is fixed at the center of the cam shaft  17   a  in the widthwise direction WD to rotate in conjunction with rotation of the cam shaft  17   a . The cam  17   b  includes a base portion  17   b   1  and a protruding portion  17   b   2  protruding from the base portion  17   b   1  toward a radial outer side. The outer periphery surface of the cam  17   b  abuts on the plate spring  17   c . The plate spring  17   c  has two surfaces each facing upward and downward, and extends along the widthwise direction WD. Both ends of the plate spring  17   c  in the widthwise direction WD are coupled to the pair of brackets  18   a  of the pinch roller supporting member  18 , respectively. The coil spring  17   d  urges the main body  18   b  of the pinch roller supporting member  18  upward. 
     The cam  17   b  abuts on the center of the top surface of the plate spring  17   c  in the widthwise direction WD. When the protruding portion  17   b   2  of the cam  17   b  abuts on the plate spring  17   c  by the rotation of the cam shaft  17   a , the plate spring  17   c  is urged downward (e.g., toward the transport roller  4 ). Thus, the cam  17   b  allows the pinch roller supporting member  18  and the pinch roller  20  to be elastically urged in the urging direction PD (e.g., downward in this embodiment) by means of the plate spring  17   c . As a result, the pinch roller supporting member  18  and the pinch roller  20  are urged toward the transport roller  4 . On the other hand, when the base portion  17   b   1  of the cam  17   b  abuts on the plate spring  17   c  by the rotation of the cam shaft  17   a  (or when the base portion  17   b   1  faces the top surface of the plate spring  17   c  without abutting on the plate spring  17   c ), the coil spring  17   d  allows the pinch roller supporting member  18  and the pinch roller  20  to be lifted toward the side opposite to the urging direction PD (e.g., upward in this embodiment). As a result, the pinch roller supporting member  18  and the pinch roller  20  are lifted in a direction away from the transport roller  4 . 
     The rotation of the cam  17   b  (and the cam shaft  17   a ) may be switched according to the operation of an urging force switching mechanism  19 . The urging force switching mechanism  19  includes a driving pulley  19   a , an endless belt  19   b , and a driven pulley  19   c . The driving pulley  19   a , which is rotatably supported by the print block  9 , may rotate in conjunction with the rotation of an operating lever which switches the urging of the thermal head  9   a  toward the platen roller  5 . The endless belt  19   b  is stretched between the driving pulley  19   a  and the driven pulley  19   c  so that the rotation of the driving pulley  19   a  is transmitted to the driven pulley  19   c . The driven pulley  19   c , which is rotatably supported by the pinch roller block  10 , is coupled to the cam shaft  17   a . Thus, the rotation of the driven pulley  19   c  allows the cam shaft  17   a  and the cam  17   b  to rotate. As a result, according to this embodiment, the urging force switching mechanism  19  may switch an urging condition of the print block  9  toward the platen roller  5  into a non-urging condition, and vice-versa. Further, according to this embodiment, the urging force switching mechanism  19  may switch an urging condition of the pinch roller  20  toward the transport roller  4  into a non-urging condition, and vice-versa. 
     As shown in the embodiments illustrated in  FIGS. 4 and 5 , the transport roller  4  and the pinch roller  20  may be arranged in the urging direction PD (e.g., up and down directions), and the driving gear  16   a  and the driven gear  16   b  of the second torque transmitting mechanism  16  may be arranged in the urging direction PD. As described above, the pinch roller  20  is elastically urged toward the transport roller  4  by means of the urging member  17 . The strip-shaped paper  2  including a printing medium such as a label may be interposed between the pinch roller  20  and the transport roller  4 . In this arrangement, in accordance with the variation of the thickness of the strip-shaped paper  2  depending on the presence or absence of a label, the pinch roller  20  may move toward or away from the transport roller  4  whose rotational center is fixed in a printing state. In the embodiment shown in  FIG. 5 , the driving gear  16   a  and the driven gear  16   b  are arranged in the urging direction PD.  FIG. 5A  shows a state in which teeth  16   c  of the driving gear  16   a  are relatively deeply engaged with teeth  16   c  of the driven gear  16   b .  FIG. 5B  shows a state in which the teeth  16   c  of the driving gear  16   a  are relatively slightly engaged with the teeth  16   c  of the driven gear  16   b . In this embodiment, the rotational center Ax 2  of the driven gear  16   b  may move toward or away, along the urging direction PD, from the rotational center Ax 1  of the driving gear  16   a  having a fixed position during printing, according to the variation in the thickness of the strip-shaped paper  2 . However, as shown in  FIGS. 5A and 5B , the rotational force of the driving gear  16   a  may be transmitted to the driven gear  16   b  as long as the teeth  16   c  of the gears  16   a  and  16   b  are engaged with each other. Further, as the diameter Da of the transport roller  4  is set to be different from the diameter Db of the pinch roller  20 , the respective diameters of the gears  16   a  and  16   b  may also vary, as shown in  FIGS. 5A and 5B . In one embodiment, the number of the respective teeth of the gears  16   a  and  16   b  may be selected such that circumferential speeds of the transport roller  4  and the pinch roller  20  are equal to each other at a portion where the transport roller  4  faces the pinch roller  20  (e.g., a portion where the strip-shaped paper  2  is interposed between the transport roller  4  and the pinch roller  20 ). 
     Further, in the embodiment shown in  FIG. 4 , the diameter Db of the pinch roller  20  is set to be smaller than the diameter Da of the transport roller  4 . As described above, the pinch roller supporting member  18  and the urging member  17  are disposed above the pinch roller  20 . In this arrangement, setting the diameter Db of the pinch roller  20  to be smaller than the diameter Da of the transport roller  4  allows the arrangement of the printer  1  to be structurally uncomplicated at the top of the pinch roller  20 . Moreover, this arrangement allows the size of the printer  1  to be smaller. 
     As mentioned in the above embodiment, the pinch roller  20  may be elastically urged against the transport roller  4  while it is driven to rotate. This may reduce the urging force of the pinch roller  20  against the transport roller  4  compared to the case where the pinch roller  20  is not rotary-driven, which in turn inhibits creasing on the strip-shaped paper  2  or reduces motor load. 
     Further, in the above embodiment, the second torque transmitting mechanism  16  may be configured to transmit the rotational force of the transport roller  4  to the pinch roller  20 . This allows the pinch roller  20  to be rotary-driven in a relatively simplified fashion. 
     Furthermore, in the above embodiment, the second torque transmitting mechanism  16  may include the driving gear  16   a , which is provided at the side of the transport roller  4 , and the driven gear  16   b , which is disposed at the side of the pinch roller  20  and is in engagement with the driving gear  16   a . This arrangement implements the second torque transmitting mechanism  16  in a relatively simplified fashion. 
     Moreover, in the above embodiment, the driving gear  16   a  and the driven gear  16   b  are engaged with each other in the urging direction PD from the pinch roller  20  to the transport roller  4 . This allows the pinch roller  20  to be separated from the transport roller  4  while the driving gear  16   a  is still engaged with the driven gear  16   b . Therefore, it is possible to implement the second torque transmitting mechanism  16 , which allows a displacement of the pinch roller  20  relative to the transport roller  4  according to the variation in thickness of the strip-shaped paper  2  and, at the same time, allows transmission of the rotational force of the transport roller  4  to the pinch roller  20 . 
     In another embodiment, the diameter Db of the pinch roller  20  is set to be smaller than the diameter Da of the transport roller  4 . This configuration allows the pinch roller supporting member  18  which supports the pinch roller  20  at the side opposite to the transport roller  4 , or the urging member  17  which elastically urges the pinch roller  20  against the transport roller  4 , to be structurally uncomplicated. Moreover, this configuration allows the size of the printer  1  to be smaller. 
     In yet another embodiment, the urging member  17  includes the plate spring  17   c . This arrangement allows implementation of an elastic member to elastically urge the pinch roller  20  against the transport roller  4 , an arrangement to support the elastic member, or an arrangement to urge the elastic member, in a relatively simplified fashion. 
     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 embodiments described herein may be embodied in a variety of other forms. For example, the urging member which elastically urges the pinch roller against the transport roller  4 , may include an elastic member other than a plate spring (e.g., a coil spring, an elastomer, etc.). Furthermore, the location at which the plate spring is disposed, or the location to which an urging force is applied by an urging member such as a cam, may be changed without departing from the spirit of the inventions. In addition, the torque transmitting mechanism may be implemented by employing a belt drive mechanism. Still further, the torque transmitting mechanism may be implemented by a member including three or more gears. The pinch roller may be rotary-driven by different torque driving mechanisms and different torque transmitting mechanisms from the aforementioned embodiments, without being rotary-driven by the strip-shaped paper. Furthermore, the pinch roller and the transport roller may be rotary-driven by different torque driving mechanisms and different torque transmitting mechanisms from the aforementioned embodiments. As an example, the platen roller, the transport roller and the pinch roller may be rotary-driven by individual torque driving mechanisms and individual torque transmitting mechanisms, respectively. Alternatively, the platen roller, the transport roller and the pinch roller may be rotary-driven by different torque transmitting mechanisms each being driven by a single torque driving mechanism. Furthermore, the specification (a scheme, structure, shape, size, length, depth, thickness, cross-section area, weight, number, material, arrangement, location or the like) of a component (a printer, a paper, a platen roller, a transport roller, a pinch roller, a torque transmitting mechanism, a driving gear, a driven gear, an urging member, a plate spring or the like) may be modified in a variety of other forms. 
     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.