Patent Publication Number: US-8537189-B2

Title: Thermal printer and driving method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2011-046911, filed on Mar. 3, 2011, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a thermal printer using thermal paper with a thermosensitive layer formed on both sides thereof, and a driving method thereof. 
     BACKGROUND 
     A thermal printer, which performs a paper feeding operation for printing by inserting thermosensitive layer-formed thermal paper between a thermal head and a platen, has been proposed. 
     In such a thermal printer, the platen is configured to apply constant pressure to the thermal head no matter whether or not printing is performed. This pressure adversely affects the life span of the thermal head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing a configuration of a major portion of an embodiment. 
         FIG. 2  is a block diagram of a control circuit of the embodiment. 
         FIG. 3  is a view showing a major portion of an IC chip-containing type thermal paper in relation to the embodiment. 
         FIGS. 4A to 4C  are flowcharts for explaining an operation of the embodiment. 
         FIG. 5  is a view showing a state in which the thermal paper is at a home position in the embodiment. 
         FIG. 6  is a view showing a state in which the thermal paper reaches a second thermal head in the embodiment. 
         FIG. 7  is a view showing a state in which the thermal paper has reached a first thermal head through the second thermal head in the embodiment. 
         FIG. 8  is a view showing a configuration in which each platen roller has moved to an open position in the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, provided is a thermal printer for printing information on thermal paper having a thermosensitive layer formed on both sides thereof, while feeding the thermal paper. The thermal printer includes first and second thermal heads installed at positions spaced apart from each other along a feeding direction of the thermal paper, the first thermal head printing on one side of the thermal paper and the second thermal head printing on the other side of the thermal paper. The thermal printer also includes a first platen installed at a position opposite the first thermal head with a feeding path of the thermal paper interposed therebetween, and configured to move to a closed position (move for closing) so as to approach the first thermal head and move to an open position (move for opening) so as to be distanced from the first thermal head, the thermal paper being interposed between the first platen and the first thermal head according to the closing movement of the first platen. A second platen is installed at a position opposite the second thermal head with the feeding path of the thermal paper interposed therebetween, and configured to move for closing so as to approach the second thermal head and move for opening so as to be distanced from the second thermal head, the thermal paper being interposed between the second platen and the second thermal head according to the closing movement of the second platen. The thermal printer further includes a control unit configured to initiate feeding of the thermal paper in a state in which the first and second platens have moved for opening, execute printing in a state in which the first and second platens have moved for closing when a front end of the thermal paper reaches the first and second thermal heads, respectively, and control the first and second platens to move for opening when the front end of the thermal paper passes through the first and second thermal heads, respectively, while returning the thermal paper, which has been cut after being printed, in the opposite direction of the feeding direction after the cutting operation. 
     Embodiments will now be described in detail with reference to the drawings. First, the configuration of a major portion of an embodiment is illustrated in  FIG. 1 . 
     A thermal paper  1 , which has a thermosensitive layer on both a front surface  1   a  and a rear surface  1   b , is wound in a rolling manner in a state in which the front surface  1   a  is at an inner side. The thermosensitive layer is made of a material which forms the color of, for example, black or red when heated at a predetermined temperature or higher. A front end of the thermal paper  1  is fed to the feeding path  4  by feeding rollers  2  and  3 , and transferred along the feeding path  4 . 
     A first thermal head  11 , facing the front surface  1   a  of the thermal paper  1 , and a second thermal head  12 , facing the rear surface  1   b  of the thermal paper  1 , are disposed along the feeding direction of the thermal paper  1 . The first and second thermal heads  11  and  12  are configured to extend in a direction perpendicular to the feeding direction of the thermal paper  1 , namely, in a widthwise direction of the thermal paper  1 , and installed to be spaced apart from each other along the feeding direction of the thermal paper  1 . The first thermal head  11  is disposed at the downstream direction with respect to the second thermal head  12  in the feeding direction of the thermal paper  1 . 
     A first platen roller  13  is disposed at a position opposite the first thermal head  11  with the feeding path  4  interposed therebetween, and a second platen roller  14  is disposed at a position opposite the second thermal head  12  with the feeding path  4  interposed therebetween. 
     As indicated by an arrow, the first platen roller  13  can move for closing so as to approach the first thermal head  11  and move for opening so as to be distanced from the first thermal head  11 . According to the closing movement of the first platen roller  13 , the thermal paper  1  is interposed between the first platen roller  13  and the first thermal head  11  and the front surface  1   a  of the thermal paper  1  is effectively brought into contact with the first thermal head  11 . A motor  13 M is installed as a power source for the closing and opening movement of the first platen roller  13 . 
     As indicated by an arrow, the second platen roller  14  can also move for closing so as to approach the second thermal head  12  and move for opening so as to be distanced from the second thermal head  12 . According to the closing movement of the second platen roller  14 , the thermal paper  1  is interposed between the second platen roller  14  and the second thermal head  12  and the rear surface  1   b  of the thermal paper  1  is effectively brought into contact with the second thermal head  12 . A motor  14 M is installed as a power source for the closing and opening movement of the second platen roller  14 . 
     The first and second platen rollers  13  and  14  have, as closing movement positions, a first closing movement position at which the distance between the respective thermal head and the corresponding platen roller is Dx and a second closing movement position at which the distance between the respective thermal head and the corresponding platen roller is Dy (&gt;Dx). 
     In the feeding direction, a cutter  5  for cutting the thermal paper  1  is disposed at a downstream direction of the first thermal head  11  and the first platen roller  13 , and a paper sensor  6  is disposed at an upstream direction of the first thermal head  11 . The paper sensor  6  includes a light emitting element for emitting light towards the feeding path  4  and a light receiving element for receiving reflected light from the thermal paper  1  on the feeding path  4 . The paper sensor  6  detects whether or not the thermal paper  1  is positioned in front of the first thermal head  11  depending on whether or not the light receiving element receives light. A paper sensor  7  is disposed at an upstream direction of the second thermal head  12  in the feeding direction. The paper sensor  7  includes a light emitting element for emitting light toward the feeding path  4  and a light receiving element for receiving reflected light from the thermal paper  1  on the feeding path  4 . The paper sensor  7  detects whether or not the thermal paper  1  is positioned in front of the second thermal head  14  depending on whether or not the light receiving element receives light. 
       FIG. 2  illustrates a block diagram of a control circuit according to the present embodiment. 
     A microcomputer including a CPU  21 , a ROM  22  for storing a control program, a RAM  23  for storing data, and the like operates as a nucleus for controlling the thermal printer. The paper sensors  6  and  7 , a communication interface  25 , a feeding driving circuit  31 , a cutter driving circuit  32 , head driving circuits  33  and  34 , platen driving circuits  35  and  36 , and a control panel  37  are connected to the CPU  21  of the microcomputer. The control panel  37  includes a manipulation unit  37   a  including a plurality of manipulation buttons and display lamps, and a liquid crystal display unit  37   b.    
     An external host device  50  is connected to the communication interface  25 . The feeding driving circuit  31  drives a feeding mechanism  40  including the feeding rollers  2  and  3  and the feeding path  4 . The cutter driving circuit  32  drives the cutter  5 . The head driving circuits  33  and  34  drive the first and second thermal heads  11  and  12 , respectively. The platen driving circuits  35  and  36  drive the platen roller driving motors  13 M and  14 M, respectively. 
     Further, the CPU  21  has the following units (1) to (4) as major functions based on a control program within the ROM  22 . 
     (1) A data sort control unit is provided, which sorts printer data D 0  supplied from the external host device  50  into first printer data D 1  with respect to the front surface  1   a  of the thermal paper  1  and second printer data D 2  with respect to the rear surface  1   b  of the thermal paper  1 . The printer data D 0 , the first printer data D 1 , and the second printer data D 2  are all stored in the RAM  23 . 
     (2) A first control unit is provided, which initiates feeding of the thermal paper  1  in a state in which the first and second platen rollers  13  and  14  have moved for opening in performing printing by at least one of the first and second thermal heads  11  and  13 ; executes printing while controlling the first and second platen rollers  13  and  14  to move for closing when a front end of the thermal paper  1  reaches the first and second thermal heads  11  and  12 , respectively; drives the cutter  5  when the end of a print position of the printing-completed thermal paper  1  passes through the position of the cutter  5  in order to cut the thermal paper  1 ; and controls the first and second platen rollers  13  and  14  to move for opening when the front end of the thermal paper  11  passes through the first and second thermal heads  11  and  12 , respectively, while returning the thermal paper  1  in the opposite direction of the feeding direction after the cutting operation. 
     (3) A second control unit is provided, which sets the first closing movement position (the distance Dx) as a normal mode of the closing movement position of the first and second platen rollers  13  and  14  when the thermal paper  1  does not include an IC chip, and sets the second closing movement position (the distance Dy) as the closing movement position of the first and second platen rollers  13  and  14  when the thermal paper  1  contains an IC chip  60  illustrated in  FIG. 3 . Whether or not the setting for the thermal paper  1  to include the IC chip  60  is set may be determined by manipulating the control panel  37 . 
     (4) A third control unit is provided, which controls the first and second platen rollers  13  and  14  to move for opening according to a certain manipulation of the control panel  37  and to be maintained in that position, which is referred to as opening movement position. This controlling is performed when the thermal paper  1  is jammed at the feeding path  4 , or in the case of repair or maintenance work performed by a service person. 
     Now, the operation of a thermal printer of one embodiment will be described with reference to  FIGS. 4A to 7 .  FIGS. 4A to 4C  show processing of the CPU  21 , and  FIGS. 5 to 7  show a change in the position of the thermal paper  1  and a change in the state of the first and second platen rollers  13  and  14 . 
     While printing is not being performed, as shown in  FIG. 5 , the platen rollers  13  and  14  move for opening so as to be separated from the first and second thermal heads  11  and  12 , respectively, and the front end of the thermal paper  1  is in standby at a feeding standby position or a home position in an upstream direction of the paper sensor  7 . 
     When the thermal paper  1  not including an IC chip is set by the control panel  37  (YES in action A 101 ), the first closing movement position of the distance Dx is set as a normal mode regarding the closing movement position of the first and second platen rollers  13  and  14  (action A 102 ). However, when the use of the thermal paper  1  including an IC chip is set by the control panel  37  (NO in action A 101 ), the second closing movement position of the distance Dy is set as an IC chip mode regarding the closing movement position of the first and second platen rollers  13  and  14  (action A 103 ). The distance Dy of the IC chip mode is greater than the distance Dx of the normal mode by the thickness of the IC chip  60 . 
     When double-sided printing is performed by the first and second thermal heads  11  and  12  (YES in action A 104 ), it is determined whether both the first and second platen rollers  13  and  14  have moved for opening (action A 105 ). If the first and second platen rollers  13  and  14  have not moved for opening (NO in action A 105 ), they are moved for opening (action A 106 ). In this state, feeding of the thermal paper  1  is initiated (action A 107 ). 
     When the front end of the fed thermal paper  1  reaches a position in an upstream direction of the second thermal head  12 , the front end of the thermal paper  1  is detected by the paper sensor  7  (YES in action A 108 ). Based on this detection, as shown in  FIG. 6 , the second platen roller  14  moves for closing (action A 109 ), and the thermal paper  1  is pressed to the second thermal head  12 . In this state, printing is executed by the second thermal head  12  (action A 110 ). 
     When the front end of the thermal paper  1 , which has passed through the position of the second thermal head  12 , reaches a position in an upstream direction of the first thermal head  11 , the front end of the thermal paper  1  is detected by the paper sensor  6  (YES in action A 111 ). Based on this detection, as shown in  FIG. 7 , the first platen roller  13  moves for closing (action A 112 ), and the thermal paper  1  is pressed to the first thermal head  11 . In this state, printing is executed by the first thermal head  11  (action A 113 ). 
     When the printing by the first and second thermal heads  11  and  12  is completed (YES in action A 114 ), the thermal paper  1  is cut by the cutter  5  when the end of the print position of the thermal paper  1  passes through the position of the cutter  5  (action A 115 ). Whether the end of the print position of the thermal paper  1  has passed through the position of the cutter  5  is detected based on a time measurement after the front end of the thermal paper  1  is detected by the paper sensor  6  and an amount of print information. 
     After the cutting by the cutter  5 , the thermal paper  1  is returned toward the home position in the opposite direction of the feeding direction (action A 116 ). At this time, when the front end of the thermal paper  1  passes through the position of the first thermal head and is detected by the paper sensor  6 , the first platen roller  13  moves for opening and, when the front end of the thermal paper  1  passes through the position of the second thermal head  12  and is detected by the paper sensor  7 , the second platen roller  14  moves for opening (S 117 ). 
     In addition, in the case of only printing on the front surface by the first thermal head  11  (NO in action A 104 , and YES in action A 118 ), it is determined whether both the first and second platen rollers  13  and  14  have moved for opening (action A 119 ). If the first and second platen rollers  13  and  14  have not moved for opening (NO in action A 119 ), they are moved for opening (action A 120 ). In this state, feeding of the thermal paper  1  is initiated (action A 121 ). When the front end of the fed thermal paper  1  reaches a position in an upstream direction of the second thermal head  12 , the front end of the thermal paper  1  is detected by the paper sensor  7  (YES in action A 122 ). Based on this detection, as shown in  FIG. 6 , the second platen roller  14  moves for closing (action A 123 ), and the thermal paper  1 , being pressed to the second thermal head  12 , is fed. Thereafter, the processing of actions  111  to  117  is executed. 
     In the case of only printing on the rear surface by the second thermal head  12  (NO in action A 104 , NO in action A 118 , and YES in action A 124 ), it is determined whether both the first and second platen rollers  13  and  14  have been moved for opening (action A 125 ). If the first and second platen rollers  13  and  14  have not been moved for opening (NO in action A 125 ), they are moved for opening (action A 126 ). In this state, feeding of the thermal paper  1  is initiated (action A 127 ). When the front end of the fed thermal paper  1  reaches a position in an upstream direction of the second thermal head  12 , the front end of the thermal paper  1  is detected by the paper sensor  7  (YES in action A 128 ). Based on this detection, as shown in  FIG. 6 , the second platen roller  14  moves for closing (action A 129 ) and the thermal paper  1  is pressed to the second thermal head  12 . In this state, printing is executed by the second thermal head  12  (action A 130 ). 
     When the front end of the thermal paper  1 , which has passed through the position of the second thermal head  12 , reaches a position in an upstream direction of the first thermal head  11 , the front end of the thermal paper  1  is detected by the paper sensor  6  (YES in action A 131 ). Based on this detection, as shown in  FIG. 7 , the first platen roller  13  moves for closing (action A 132 ), and the thermal paper  1 , being pressed to the first thermal head  11 , is fed. Thereafter, the processing of actions  114  to  117  is executed. 
     As described above, only when the thermal paper  1  passes between the second thermal head  12  and the second platen roller  14  does the second platen roller  14  move for closing, and in other cases, the second platen roller  14  moves for opening; and only when the thermal paper  1  passes between the first thermal head  11  and the first platen roller  13  does the first platen roller  13  move for closing, and in other cases, the first platen roller  13  moves for opening, whereby the pressure applied to the first and second thermal heads  11  and  12  can be reduced to be as small as possible while transferring between feeding and returning the thermal paper  1  appropriately. Accordingly, the life spans of the first and second thermal heads  11  and  12  can be extended. 
     When the thermal paper  1  is a type containing an IC chip  60 , the positions of the closing movement of the first and second platen rollers  13  and  14  are set to be away from the first and second thermal heads  11  and  12 , respectively, compared with a general case, whereby the IC chip  60  within the thermal paper  1  is not unnecessarily damaged or interfered with. 
     When the thermal paper  1  is jammed on the feeding path  4 , or in the case of repair or maintenance work, a menu button and a pause button of the manipulation portion  37   a  of the control panel  37  may be pushed at the same time. In this case, as shown in  FIG. 8 , both the first and second platen rollers  13  and  14  move for opening and are maintained in the opening movement position. According to this opening movement, the thermal paper  1  can be easily removed from the feeding path  4 , and thus, the work of the user or service person can be considerably reduced. 
     Further, if a type of thermal paper  1  in which a plurality of labels are adhered on a band-shaped backing sheet is used, when the thermal paper  1  is transferred in a reverse direction of the feeding direction after being cut and returned to the home position, an end portion of each of the labels may come off upon being brought into contact with the first and second thermal heads  11  and  12 . Thus, in a case where the label-adhered type thermal paper  1  is used, the first and second platen rollers  13  and  14  move for opening at a timing when the boundary position of the backing sheet and the label passes the first and second platen rollers  13  and  14 , thereby preventing the label from coming off. 
     As used in this application, objects for executing the actions can refer to a computer-related object, hardware, a combination of hardware and software, software, or software in execution. For example, an object for executing an action can be, but is not limited to, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and a computer. By way of illustration, both an application running on an apparatus and the apparatus can be the object. One or more objects can reside within a process and/or thread of execution and an object can be localized on one apparatus and/or distributed between two or more apparatuses. 
     A program for realizing the functions can be recorded in an apparatus, can be downloaded through a network to an apparatus, or can be installed in an apparatus from a computer readable storage medium storing the program therein. The form of a computer readable storage medium can be any form as long as the computer readable storage medium can store programs and is readable by an apparatus such as a disk type ROM and a solid-state computer storage media. The functions obtained by installation or download in advance in this manner can be realized in cooperation with an OS (Operating System) in an apparatus. 
     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.