JP2009255348A - Thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of printing crush by solving such a problem that when the contact part of a paper with a heating element is sagged, the printing crush occurs in an initial printing stage and is eliminated by empty feed before a printing operation, but extra blank part is produced on the paper, to deteriorate appearance as the printing result. <P>SOLUTION: In a thermal printer, a motor as the drive source of a platen 104 is reversely rotated and driven before starting printing, to feed a receipt sheet RT back and continuously rotated and driven forward without stopping the drive of the motor, to feed the receipt sheet RT forward. The heating drive of the heating element 131 is started to start printing at the timing of performing the forward feed (forward rotation drive) only for the same time as the time when the back feed (reverse rotation drive) is performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermal printer such as a receipt printer.

  Conventionally, in a thermal printer, paper (thermal paper) is conveyed by friction with a rotating platen to which power of a stepping motor is transmitted. In this conveyance process, the heating element of the thermal head is driven to generate heat, whereby printing on the paper is performed.

JP-A-9-216432

  The sheet is pressed by the platen and the thermal head, and its position is fixed unless the stepping motor is driven.

  By the way, slack may occur at the contact portion of the paper with the thermal head due to the operation of the cutter mechanism in the thermal printer. Then, if printing is performed with this slackness occurring, printing collapse occurs.

  Therefore, in order to prevent the occurrence of such printing crushing, it is conceivable to first feed the paper for a predetermined distance without printing (blank feed), and then start printing the first line (for example, Patent Documents). 1 paragraphs 0043-0045). According to this, the slack of the paper is eliminated during the idle feed, and the operation of the stepping motor is stabilized during the idle feed.

  However, when such an empty feed is performed, it is inevitable that a blank portion having no print is formed on the paper for the empty feed. For this reason, the print result when the empty feed is performed becomes very unsightly due to the extra blank portion.

  An object of the present invention is to provide a thermal printer that prevents the occurrence of printing crushing in the initial printing stage without deteriorating the appearance of the printing result due to extra blanks.

  The thermal printer of the present invention has a platen that is rotationally driven, a thermal head in which a heating element that is arranged in a line and driven to generate heat is brought into contact with the platen via a sheet conveyed through a conveyance path, and is developed in an image memory. A print control unit that heat-drives the heating element based on the dot pattern of the image data, and forward feed the paper along the transport path by rotating forward, and paper along the transport path by rotating in reverse A feed roller that back-feeds the motor, a forward / reverse rotatable motor, and a power transmission mechanism that transmits the forward rotation of the motor as the forward rotation of the transport roller, and transmits the reverse rotation of the motor as the reverse rotation of the transport roller. Then, after the motor is driven in reverse rotation, the motor is continuously driven in normal rotation, and the normal rotation drive is the same time as the reverse rotation drive. In it has done timing and means for starting the heating drive of the heating element to the print controller.

  According to the present invention, the paper is continuously fed forward after being fed back during printing. At this time, since printing is started at the timing of forward feed for the same time as the back feed, the print start position of the paper does not change, and no extra blank portion is generated in the print result. Further, since the back feed and the forward feed are continuously executed, the paper does not become slack due to the impact of the printer operation between the back feed and the forward feed. Since the slack of the paper is eliminated by the momentum of the forward feed after the back feed, the printing is not crushed. Further, even when the motor is unstable at the time of starting, the operation is stabilized by the start of printing. In this way, it is possible to prevent the occurrence of printing crushing at the initial printing stage without deteriorating the appearance due to the extra blank.

  An embodiment of the present invention will be described with reference to FIGS. The thermal printer of this embodiment is an example applied to a receipt printer 101 that performs printing on a receipt paper RT that is thermal paper.

  FIG. 1 is a vertical side view schematically showing the structure of the receipt printer 101. The receipt printer 101 has a main body housing 102 incorporated in the main body of the POS terminal 11 (see FIG. 4). An openable / closable cover 102 a is provided on the upper surface portion of the main body housing 102. Further, on the back side (the right side in FIG. 1) inside the main body housing 102, a paper storage unit 103 for storing the receipt paper RT wound in a roll shape is provided. The receipt printer 101 is a so-called throw-in printer. The receipt paper RT is stored in the paper storage section 103 with the cover 102a opened, and the end is pulled out. The cover 102 a is provided with a pinch roller 109 that is in contact with the main body housing 102 in the closed state, and the end portion of the receipt paper RT that is pulled out is pressed by the pinch roller 109.

  Inside the main body housing 102, there is a conveyance path 106 through which the receipt paper RT is conveyed by connecting the paper storage portion 103 and a paper discharge port 108 provided on the front side (left side in FIG. 1) of the main body housing 102. Is formed.

  A printing mechanism 105 that conveys the receipt paper RT and performs printing is provided at a position along the conveyance path 106. The printing mechanism 105 is mainly configured by a platen 104 that is rotationally driven and a thermal head 112 that is disposed to face the platen 104. The thermal head 112 is elastically pressed by a spring (not shown), and comes into contact with the platen 104 via the receipt paper RT conveyed through the conveyance path 106.

  The receipt paper RT is conveyed along the conveyance path 106 by the rotation of the platen 104. At this time, the platen 104 is rotationally driven by the rotational force of the stepping motor 110 (see FIG. 4) built in the main body housing 102 being transmitted through the power transmission mechanism 141 (see FIG. 2).

  FIG. 2 is a perspective view schematically showing the power transmission mechanism 141. The power transmission mechanism 141 includes a motor gear 143 attached to the motor shaft 142 of the stepping motor 110, an intermediate gear 145 attached to the intermediate shaft 144, and a platen gear 147 attached to the platen shaft 146 of the platen 104. The motor gear 143, the intermediate gear 145, and the platen gear 147 are meshed in this order.

  When the stepping motor 110 is rotationally driven, the rotational force of the stepping motor 110 is transmitted in the order of the motor gear 143, the intermediate gear 145, and the platen gear 147, and the platen 104 is rotationally driven. Since the stepping motor 110 is rotatable forward and backward, and both the intermediate shaft 144 and the platen shaft 146 are held so as to be rotatable forward and backward, both forward and reverse rotational forces of the stepping motor 110 are applied to the platen 104. Communication is possible.

  Here, the conveyance of the receipt paper RT in the direction toward the paper discharge port 108 (lower left direction in FIG. 2) is called “forward feed”, and the receipt paper in the direction toward the paper storage unit 103 (upper right direction in FIG. 2). RT conveyance is called “back feed”. Further, the rotation of the platen 104 for forward feeding the receipt paper RT is “forward rotation”, and the rotation of the platen 104 for back feeding the receipt paper RT is “reverse rotation”. Then, the rotation of the stepping motor 110 transmitted as the normal rotation of the platen 104 by the power transmission mechanism 141 is set as “forward rotation”, and the rotation of the stepping motor 110 transmitted as the reverse rotation of the platen 104 is set as “reverse rotation”. . Therefore, the power transmission mechanism 141 transmits the normal rotation of the stepping motor 110 as the normal rotation of the platen 104, and transmits the reverse rotation of the stepping motor 110 as the reverse rotation of the platen 104.

  Returning to the description of FIG. A cutter mechanism 107 is provided at the paper discharge port 108 of the main body housing 102. The cutter mechanism 107 is for cutting the receipt paper RT that is forward-fed by the forward rotation of the platen 104 and is discharged from the paper discharge port 108. Such a cutter mechanism 107 is configured by combining a fixed blade and a movable blade having a plate-like plate shape, and power is transmitted by driving a motor (not shown) different from the stepping motor 110. The receipt paper RT is cut by sliding the movable blade.

  FIG. 3 is an enlarged vertical side view showing the printing mechanism 105. A line-shaped glaze layer 132 is provided along the width direction of the receipt paper RT to be conveyed in a portion facing the platen 104 in the thermal head 112, and a heating element 131 is formed on the glaze layer 132. Yes.

  The receipt paper RT to be fed forward is pulled out from the state stored in the paper storage unit 103, and is conveyed to a position between the heating element 131 of the thermal head 112 and the platen 104 (hereinafter referred to as a printing position PP). . Then, when the heating element 131 generates heat, the portion located at the printing position PP on the receipt paper RT is colored. In this way, printing in the main scanning direction is performed. Further, the printing in the sub-scanning direction is performed by the movement of the receipt paper RT with respect to the printing position PP generated by the conveyance.

  FIG. 4 is a block diagram showing the electrical connection of the receipt printer 101. The receipt printer 101 is provided with a CPU 117 that executes various arithmetic processes and centrally controls each unit. The CPU 117 includes a ROM 119 that stores fixed data in a fixed manner, and a RAM 120 that stores variable data in a rewritable manner. Are connected via the system bus 121. The ROM 119 stores a control program, and the CPU 117 executes various processes according to the control program stored in the ROM 119 while using the RAM 120 as a work area.

  Further, the receipt printer 101 includes a motor driver 122 for driving and controlling a stepping motor 110 for rotationally driving the platen 104 and a thermal head 112 by driving the heating element 131 to generate heat. And a head controller 140 for performing a printing operation. The motor driver 122 and the head controller 140 are connected to the CPU 117 via the system bus 121.

  Further, an interface 129 and an image memory 130 are also connected to the CPU 117 via the system bus 121. The receipt printer 101 receives print data transferred from the POS terminal 11 as a host device via the interface 129. Then, the CPU 117 of the receipt printer 101 converts this print data into image data composed of a dot pattern and develops it in the image memory 130.

  The CPU 117 outputs data for each line from the image data composed of a plurality of dot patterns developed in the image memory 130 to the head controller 140, and the head controller 140 generates heat from the heating element 131 corresponding to the dot having the dot pattern. To drive. At this time, the head controller 140 outputs a strobe signal to the heating element 131.

  In the receipt printer 101, a sensor 125 for detecting the near end of the receipt paper RT is disposed at a position along the transport path 106, and this sensor 125 is connected to the system bus 121 via the I / O port 128. Has been.

  In addition, a thermistor and an AD converter (both not shown) are attached to the head substrate (not shown) of the thermal head 112, and a detection signal (head temperature information) by this thermistor is converted to a digital value by the AD converter. It is connected so that it is converted and taken into the CPU 117.

  The receipt printer 101 has a motor (not shown) for driving the cutter mechanism, and this motor is also connected to the CPU 117 via a motor driver (not shown).

  Next, processing executed by the receipt printer 101 when performing printing on the receipt paper RT based on print data transferred from the POS terminal 11 in such a configuration will be described.

  FIG. 5 is a flowchart showing the flow of processing executed by the receipt printer 101. The CPU 117 of the receipt printer 101 waits for reception of print data transferred from the POS terminal 11 via the interface 129 (step S101). When the CPU 117 of the receipt printer 101 determines that the print data is received from the POS terminal 11 (Y in step S101), the received print data is converted into image data composed of a dot pattern and developed in the image memory 130. (Step S102).

  Next, the CPU 117 of the receipt printer 101 determines whether or not there is a dot pattern on the first line of the image data developed in the image memory 130 (step S103).

  If it is determined in step S103 that there is a dot pattern on the first line of the image data (Y in step S103), the CPU 117 of the receipt printer 101 rotates the stepping motor 110 in a reverse direction for a predetermined time to drive the platen 104. After the receipt paper RT is back-fed by reverse rotation (step S104), the stepping motor 110 is continuously rotated in the forward direction without stopping the driving of the stepping motor 110, and the platen 104 is rotated forward. The receipt paper RT is fed forward. Then, the CPU 117 causes the head controller 140 to drive the heating element 131 to generate heat at the timing when the stepping motor 110 is driven to rotate forward for the same time as the reverse rotation driving described above (step S105). . The time during which the stepping motor 110 is driven to rotate in reverse is the time during which the receipt paper RT is back-fed by several mm by the platen 104. Then, the CPU 117 of the receipt printer 101 continues the forward rotation of the stepping motor 110 to continue the forward feeding of the receipt paper RT, and prints for the second and subsequent lines (step S106).

  On the other hand, if it is determined in step S103 that there is no dot pattern in the first line of the image data (N in step S103), the CPU 117 of the receipt printer 101 does not execute the processes in steps S104 to S106. A normal printing process is executed (step S107). That is, the CPU 117 rotates the platen 104 in the reverse direction and does not back feed the receipt paper RT as in step S104, and forwardly drives the stepping motor 110 to forward feed the receipt paper RT and also causes the head controller 140 to generate heat. The body 131 is driven to generate heat. In this way, normal printing on the receipt paper RT is executed.

  Next, the state of the receipt paper RT conveyed when it is determined in step S103 in the flowchart of FIG. 5 that there is a dot pattern on the first line of the image data (Y in step S103) will be described based on FIG. To do.

  FIG. 6 is a side view showing a state of the receipt paper RT being conveyed. FIG. 6A shows a state before the start of conveyance. As shown in FIG. 6A, the upstream portion of the printing position PP on the receipt paper RT may be loosened. If the receipt paper RT is “forward-fed” with such a slack and the first line is printed, the printing will be crushed.

  Therefore, as shown in FIG. 6B, the platen 104 is reversely rotated to back feed the receipt paper RT. At this time, since the roll-like portion stored in the paper storage portion 103 of the receipt paper RT is not rewound or the like, as shown in FIG. 6B, the print position PP on the receipt paper RT by this back feed. A greater slack occurs in the portion from the paper storage unit 103 to the paper storage unit 103. At this time, the portion of the receipt paper RT that was located at the print position PP in the state before the start of conveyance (FIG. 6A) has moved to the upstream side from the print position PP that includes this slack.

  Then, as shown in FIG. 6C, the receipt paper RT eliminates the slack (FIG. 6B) caused by the back feed by the forward rotation of the platen 104 that is continuously executed, and forwards the receipt paper RT. Feeded. Then, as shown in FIG. 6C, the receipt paper RT is transported vigorously and passes through the print position PP without causing a new slack. Since the first line is printed at the same time as the reverse rotation for the same time as the reverse rotation, the printing is performed on the portion of the receipt paper RT that was positioned at the print position PP before the start of conveyance (FIG. 6A). On the other hand, the first line is printed. That is, the first line is printed without any deviation in the portion where the first line should be printed.

  As described above, according to the present embodiment, since printing is started at the timing when the receipt paper RT is back-fed for a predetermined time and forward-fed for the same time, an extra blank portion is generated in the print result (receipt). Absent.

  In addition, since the back feed and the forward feed are continuously executed, there is no period in which the receipt paper RT stops after the back feed. Therefore, during this period, the receipt paper RT is moved by another operation of the receipt printer 101. There is no occurrence of slack.

  Then, since printing is started during forward feed executed continuously after back feed, printing is performed on the receipt paper RT in a state in which the looseness of the paper is eliminated by the momentum of conveyance, Print crushing does not occur.

  In addition, since printing is performed after back feed and forward feed for a predetermined time, the operation of the stepping motor 110 is stabilized before the start of printing by the thermal head 112.

  Thus, in the receipt printer 101 of the present embodiment, it is possible to prevent the occurrence of printing crushing at the initial printing stage without deteriorating the appearance due to the blank.

  In this embodiment, in step S103 of the flowchart of FIG. 5, the CPU 117 determines whether or not there is a dot pattern in the first line of the image data. The object to be determined is not limited to the first line, and it may be determined whether or not there is a dot pattern up to several lines of image data.

It is a vertical side view which shows roughly the structure of a receipt printer. It is a perspective view which shows a power transmission mechanism schematically. It is a vertical side view which expands and shows a printing mechanism. It is a block diagram which shows the electrical connection of a receipt printer. It is a flowchart which shows the flow of the process performed with a receipt printer. It is a side view which shows the state of the receipt paper conveyed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Receipt printer (thermal printer), 104 ... Platen (conveyance roller), 106 ... Conveyance path, 112 ... Thermal head, 110 ... Stepping motor (motor), 130 ... Image memory, 131 ... Heating element, 140 ... Head controller ( Print control unit), 141 ... power transmission mechanism, RT ... receipt paper (paper)

Claims (4)

A rotationally driven platen;
A thermal head that is arranged in a line and that is driven to generate heat is in contact with the platen via a sheet conveyed through a conveyance path;
A print controller for driving the heat generating element based on a dot pattern of image data developed in an image memory;
A feed roller that forward feeds the paper along the transport path by rotating forward, and a back roller that feeds the paper along the transport path by rotating backward;
A motor that can rotate forward and backward, and
A power transmission mechanism for transmitting a normal rotation of the motor as a normal rotation of the transport roller, and transmitting a reverse rotation of the motor as a reverse rotation of the transport roller;
After the motor is driven in reverse rotation, the motor is continuously driven in normal rotation, and the print control unit starts the heat generation drive of the heating element at the timing when the normal rotation drive is performed for the same time as the reverse rotation drive. Means,
Thermal printer equipped with. When there is no dot pattern up to a predetermined line of the image data developed in the image memory, when the print control unit starts the heat generation driving of the heating element, the motor is not rotated in the reverse direction but is driven in the forward direction. To
The thermal printer according to claim 1. The motor is a stepping motor;
The thermal printer according to claim 1 or 2. The transport roller is a roller-shaped platen.
The thermal printer as described in any one of Claim 1 thru | or 3.

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