Patent Publication Number: US-8994766-B2

Title: Printer

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. 2013-154827, which was filed on Jul. 25, 2013, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a printer that performs desired printing on a print-receiving medium. 
     2. Description of the Related Art 
     There are known printers that perform printing utilizing a driving force of a pulse motor. In this printer, feeding means (a roller driving motor) feeds a print-receiving medium (cover film) by a driving force of a pulse motor (roller driving motor), and a thermal head performs the desired printing on the print-receiving medium thus fed. The pulse motor rotates at a predetermined angle by applying a single pulse signal (switching the excitation phase to the next state), and the rotation speed is controlled by shortening and lengthening the interval at which the pulse is applied. The thermal head comprises a plurality of heating elements arranged in a direction orthogonal to the transport direction. This plurality of heating elements performs printing by forming dots on the respective printing lines of the print-receiving medium. Specifically, in response to the print-receiving medium being fed by the feeding means and the printing lines of the print-receiving medium sequentially passing the positions of the heating elements, the conduction mode of the heating elements is sequentially switched on a per line print data (section of print data divided into one of the printing line units) basis. With this arrangement, it is possible for the thermal head to perform printing at a printing speed that matches the feeding speed of the print-receiving medium by the feeding means. 
     In the printer that uses the pulse motor, the coordination mode in a case where feeding and printing are performed in coordination as described above may be switched between one coordinated state wherein the pulse motor rotates at a relatively fast rotation speed and another coordinated state wherein the pulse motor rotates at a relatively slow rotation speed, executed to correct the print length so that it is shorter. At such a time, when the conduction of the plurality of heating elements and the driving of the pulse motor are controlled in coordination and the mode is switched from the one coordinated state to the other coordinated state or conversely from the other coordinated state to the one coordinated state, the possibility exists that the input of the pulse signal and the switching of the excitation phase will become mismatched if there is a large difference in the rotation speeds of the pulse motor, causing difficulties in smooth motor operation. 
     SUMMARY 
     It is therefore an object of the present disclosure to provide a printer capable of maintaining smooth motor operation even in a case where two coordination modes with different rotation speeds of the pulse motor are switched when feeding and printing are controlled in coordination. 
     In order to achieve the above-described object, according to the aspect of the present application, there is provided a printer comprising a pulse motor configured to drive by inputting a pulse signal, a feeder configured to feed a print-receiving medium by using a driving force of the pulse motor, a thermal head having a plurality of heating elements that is arranged in a direction orthogonal to the transport direction in which the print-receiving medium is fed by the feeder and is configured to at least form respective dots on respective printing lines that is formed by dividing the print-receiving medium in a transport direction in terms of a print resolution, and a controller, the controller being configured to execute a first control that achieves a first coordinated state wherein a pulse/dot ratio between a number of outputs of the pulse signal to the pulse motor and a number of prints of line print data that is formed by dividing print data per each of the printing line when the pulse motor constantly rotates at a first rotation speed is set to a constant first ratio that is not 0, by means of controlling a conduction of the plurality of heating elements and a driving of the pulse motor in coordination, a second control that achieves a second coordinated state wherein the pulse/dot ratio when the pulse motor constantly rotates at a second rotation speed slower than the first rotation speed is set to a constant second ratio that is smaller than the first ratio and not 0, by means of controlling the conduction of the plurality of heating elements and the driving of the pulse motor in coordination, and a switching control that gradually decreases the pulse/dot ratio from the first ratio to the second ratio when the first coordinated state is switched to the second coordinated state, and gradually increases the pulse/dot ratio from the second ratio to the first ratio when the second coordinated state is switched to the first coordinated state, by means of controlling the conduction of the plurality of heating elements and the driving of the pulse motor in coordination. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing the outer appearance of the frontward side of a label producing apparatus of an embodiment of the present disclosure. 
         FIG. 2  is a perspective view showing the outer appearance of the rearward side of a label producing apparatus of an embodiment of the present disclosure. 
         FIG. 3  is a perspective view showing the structure of the inside of the cover. 
         FIG. 4  is a perspective view showing the internal structure of the rearward side of the apparatus main body with the battery not stored. 
         FIG. 5  is a plan view showing the internal structure of the rearward side of the apparatus main body with the battery not stored. 
         FIG. 6  is a functional block diagram showing the control system of the label producing apparatus. 
         FIG. 7A  is an explanatory view for conceptually explaining an example in which the pulse motor is controlled using four pulses as a dot unit. 
         FIG. 7B  is an explanatory view for conceptually explaining an example in which the pulse motor is controlled using four pulses as a dot unit. 
         FIG. 8A  is an explanatory view for explaining the behavior that changes the pulse/dot ratio in a regular interval and a print length correction interval. 
         FIG. 8B  is an explanatory view for explaining the behavior that changes the pulse/dot ratio in a regular interval and a print length correction interval. 
         FIG. 9  is an explanatory view showing the behavior of the rotation speed of the pulse motor when the pulse motor transitions from a regular interval to a print length correction interval in a comparison example with respect to an embodiment of the present disclosure. 
         FIG. 10A  is an explanatory view showing the behavior of the rotation speed of the pulse motor when the pulse motor transitions from the regular interval to the print length correction interval. 
         FIG. 10B  is an explanatory view showing the behavior of the rotation speed of the pulse motor when the pulse motor returns from the print length correction interval to the regular interval in an embodiment of the present disclosure. 
         FIG. 11  is an explanatory view showing a specific example of the gradual decrease and gradual increase control of the rotation speed of the pulse motor based on an embodiment of the present disclosure. 
         FIG. 12  is a flowchart showing the control procedure executed by the CPU. 
         FIG. 13  is a flowchart showing the detailed procedure of the pulse/dot ratio setup processing of step S 50 . 
         FIG. 14  is an explanatory view showing a specific example of the behavior of the rotation speed of the pulse motor in a modification where the rotation speed of the pulse motor in the print length correction interval is revised downward. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following describes an embodiment of the present disclosure with reference to accompanying drawings. Note that, in the descriptions below, the terms “up,” “down,” “front,” “rear,” and “width” of the label producing apparatus  1  respectively correspond to the direction of the arrows suitably indicated in the respective figures, such as  FIG. 1 , and the term “thickness” of the label producing apparatus  1  denotes the thickness in the front-rear direction. 
     Overall Structure of Label Producing Apparatus 
     As shown in  FIG. 1  and  FIG. 2 , a label producing apparatus  1  (equivalent to the printer) is a handheld electronic device held in the hands of an operator. The label producing apparatus  1  comprises an apparatus main body  2  and a cover  3  detachably mounted to the rear surface of this apparatus main body  2 . 
     The apparatus main body  2  has a thin, flat substantially rectangular parallelepiped shape that is long in the up-down direction. A liquid crystal display part  4  for displaying print data, setting screens, and the like is disposed in the upper area of the front surface of this apparatus main body  2 , and a keyboard  5  for operating the label producing apparatus  1  is disposed on the lower side of the liquid crystal display part  4 . A key group that includes character keys for characters, symbols, numbers, and the like, and various function keys is disposed on this keyboard  5 . A cut operation lever  6  for cutting a label tape with print (described later) is disposed in the upper area of a side wall part  2   a  on one width-direction side (left side in  FIG. 1 , right side in  FIG. 2 ) of the apparatus main body  2 . 
     Cover Structure 
       FIG. 3  shows the structure of the inside of the cover  3 . As shown in  FIG. 3 , the cover  3  comprises a bottom part  45 , a side surface part  46   a  that stands on one width-direction side (upper left side in  FIG. 3 ) of the bottom part  45 , and a side surface part  46   b  that stands on the other width-direction side (lower right side in  FIG. 3 ) of the bottom part  45 , and is formed so that the side view from the up-down direction is substantially box-like in shape with an opening on the left. A protruding piece  47  that stands in the thickness direction of the apparatus main body  2  from the substantial center is formed in the upper end area of the bottom part  45 . The side surface part  46   a  on the above described one width-direction side is formed into a stepped shape in which the height in the standing direction (the same direction as the front-rear direction) gradually decreases from the upper end area to the lower end area in three steps. Similarly, the side surface part  46   b  on the above described other width-direction side is formed into a stepped shape in which the height in the standing direction gradually decreases from the upper end area to the lower end area in two steps. 
     An insertion piece  48  that inserts into an engaging hole  2   c   1  (refer to  FIG. 4  described later) disposed in two locations in the width direction of a lower part  2   c  of the apparatus main body  2  when the cover  3  is mounted in the rear surface area of the apparatus main body  2  is disposed in two width-direction locations on the lower end of the bottom part  45  of the cover  3 . 
     Further, a square frame-shaped first rib  49  set in the width direction and up-down direction of the apparatus main body  2 , and a second rib  50  comprising an arc-shaped notch  50   a  in three width-direction locations, disposed further in proximity to the lower side of the first rib  49 , stand in the lower area of the bottom part  45  of the cover  3 . The heights of the ribs  49 ,  50  are respectively set so that the height of the standing-direction upper end of the first rib  49  and the height in the standing direction of the arc center area of the notch  50   a  of the second rib  50  are substantially the same. 
     The first rib  49  comes in contact with and presses against a front surface of a battery (not shown) when the battery is stored in a battery storage part  30  (refer to  FIG. 4 ,  FIG. 5 , and the like described later) and the cover  3  is mounted in the rear surface area of the apparatus main body  2 . 
     In mounting the cover  3  in the rear surface area of the apparatus main body  2 , the two insertion pieces  48  of the lower end of the cover  3  are inserted into the two engaging holes  2   c   1  of the lower part  2   c  of the apparatus main body  2 , and the protruding piece  47  of the upper end of the cover  3  is inserted and locked into a locking opening part  9  (refer to  FIG. 4  described later) of the upper end of the apparatus main body  2 . With this arrangement, the cover  3  is mounted in the rear surface area of the apparatus main body  2 , and covers a label producing part  10  and the battery storage part  30  of the apparatus main body  2  (refer to  FIG. 4  described later). 
     Label Producing Mechanism of Label Producing Apparatus 
     As shown in  FIG. 4  and  FIG. 5 , the apparatus main body  2  comprises the label producing part  10  and the battery storage part  30 . The label producing part  10  and the battery storage part  30  are separated by a housing part  8  that houses a control board (not shown), a pulse motor  63   a  (refer to  FIG. 6  described later) for driving a platen roller  24  described later, and the like. Further, as shown in  FIG. 4  and  FIG. 5 , a step part  7  comprising a shape corresponding to the end area of the releasing side of the cover  3  is disposed on the side wall parts  2   a  and  2   b  of the above described one and other width-direction sides of the apparatus main body  2 . A locking opening  9  is disposed on the upper end of the apparatus main body  2 . 
     The label producing part  10  comprises a concave-shaped cartridge holder  12  for detachably mounting a cartridge  11 , disposed so as to occupy a majority of the substantial upper half of the apparatus main body  2 , and a printing and feeding mechanism  13  disposed in a region that includes the above described other width-direction side (left side in  FIG. 4  and  FIG. 5 ) of the cartridge holder  12 . The cartridge  11 , as shown in  FIG. 5 , internally comprises a base tape roll  14 , a cover film roll  15 , an ink ribbon roll  16 , an ink ribbon take-up roller  17 , and a feeding roller  18 . 
     The printing and feeding mechanism  13  comprises a support shaft  19  of the base tape roll  14 , a support shaft  20  of the cover film roll  15 , a support shaft  21  of the ink ribbon roll  16 , a take-up shaft  22  of the ink ribbon, a thermal head  23 , the platen roller  24  (equivalent to the feeder), a driving shaft  25  of the feeding roller  18 , a pressure roller  26 , and the like. The platen roller  24  and the pressure roller  26  are installed on a roll holder  27 , and can be switched between a printing and feeding position (the position shown in  FIG. 5  and the like) where they contact the thermal head  23  and the feeding roller  18 , and a standby position (not shown) where they are separated from the thermal head  23  and the feeding roller  18 , respectively, by the oscillation of the roll holder  27 . 
     During print label production, the platen roller  24  and the pressure roller  26  are switched to the printing and feeding position. The platen roller  24  switched to the printing and feeding position rotates by the driving from the pulse motor  63   a  on the apparatus main body  2  side, and presses the cover film (equivalent to the print-receiving medium; not shown) fed out from the cover film roll  15  and the ink ribbon (not shown) fed out from the ink ribbon roll  16  against the thermal head  23 . With this arrangement, the thermal head  23  performs desired printing in accordance with print data on the cover film, and the platen roller  24  feeds the cover film and ink ribbon on which printing has ended toward the feeding roller  18 . The ink ribbon on which printing has ended is subsequently separated from the cover film and taken up by the ink ribbon take-up roller  17 . 
     On the other hand, the pressure roller  26  switched to the printing and feeding position presses the cover film on which printing has ended, fed by the platen roller  24 , and the base tape (not shown) fed out from the base tape roll  14  against the feeding roller  18  that rotates by the driving from the driving shaft  25  connected to the pulse motor  63   a  (refer to  FIG. 6  described later). With this arrangement, the feeding roller  18  feeds a label tape with print toward a label discharging exit  29  disposed on the upper end of the apparatus main body  2  while bonding the cover film on which printing has ended and the base tape to form the label tape with print. Then, an operator manually operates the cut operation lever  6  at a predetermined point in time when the label tape with print has been discharged from the label discharging exit  29 , thereby operating a cutter  28  arranged near the label discharging exit  29  and cutting the label tape with print to form a print label of a desired length. 
     The battery storage part  30  is formed as a concave part that is long in the width direction of the apparatus main body  2  and has a substantially rectangular shape in a plan view, and can alternatively store a plurality (six in this example) of cylindrical-shaped dry cells (not shown) or one rectangular parallelepiped shaped battery (a lithium ion battery pack, for example; not shown). 
     Control System of Label Producing Apparatus 
     Next, the control system of the label producing apparatus  1  will be described with reference to  FIG. 6 . 
     As shown in  FIG. 6 , a control circuit  70  is disposed on the control board (not shown) of the label producing apparatus  1 . A CPU  74  is disposed on the control circuit  70 , and a ROM  76 , a RAM  78 , an EEPROM  77 , and an input/output interface  71  are connected to the CPU  74  via a data bus. Note that nonvolatile memory such as flash memory may be used in place of the EEPROM  77 . 
     Various programs (such as a control program that executes the respective procedures of the flows of  FIG. 12  and  FIG. 13  described later, for example) required for controlling the label producing apparatus  1  are stored in the ROM  76 . The CPU  74  performs various operations based on the various programs stored in this ROM  76 . 
     The RAM  78  temporarily stores various operation results from the CPU  74 . A label image memory  78 A and the like are disposed on this RAM  78 . 
     The EEPROM  77  stores various information. 
     A thermal head driving circuit  61 , a motor driving circuit  63 , the above described keyboard  5 , the above described liquid crystal display part  4 , and the like are connected to the input/output interface  71 . 
     The thermal head driving circuit  61  drives the above described thermal head  23 . The thermal head  23  comprises a plurality of heating elements (not shown) arranged in a direction orthogonal to the transport direction. This plurality of heating elements performs printing by forming dots on the respective printing lines of the cover film, based on the control of the above described thermal head driving circuit  61  (details described later). 
     The motor driving circuit  63  rotationally drives the pulse motor  63   a  and controls the rotation speed by a pulse signal applied to the above described pulse motor  63   a . The motor driving circuit  63  drives the pulse motor  63   a , thereby rotating the above described ink ribbon take-up roller  17  via a gear (not shown). Further, the rotation of the gear is transmitted to a platen roller gear and a pressure roller gear (not shown), and the platen roller gear and the pressure roller gear then rotate, rotating the above described platen roller  24  and the pressure roller  26 . 
     In such a control system wherein the control circuit  70  serves as the core, when the operator inputs a predetermined label production instruction via the keyboard  5 , the platen roller  24 , the pressure roller  26 , and the like are driven via the motor driving circuit  63  and the pulse motor  63   a , and the cover film and the like are fed. Further, in synchronization therewith, a plurality of heating elements of the thermal head  23  is selectively heated and driven via the thermal head driving circuit  61 , and printing of a print object is performed on the above described fed cover film. With this arrangement, in the end, a print label wherein the print object is formed on the cover film is produced. 
     Special Characteristic of the Embodiment 
     The special characteristic of this embodiment lies in the technique when the coordination mode is switched in the coordinated control between tape feeding by the above described pulse motor  63   a  and print formation (printing) by the above described thermal head  23 . In the following, details on the functions will be described in order. 
     General Characteristics of Pulse Motor 
     In the label producing apparatus  1  of this embodiment, the platen roller  24  feeds the cover film by the driving force of the above described pulse motor  63   a , and the thermal head  23  performs desired printing on the cover film thus fed. The pulse motor  63   a , as shown in  FIG. 7A  and  FIG. 7B , rotates at a predetermined angle by applying a single pulse signal (switching the excitation phase to the next state), and the rotation speed is controlled by shortening and lengthening the interval at which the pulse is applied. The rotation speed can be accelerated by gradually shortening the interval, and decelerated by gradually lengthening the interval. 
     Further, the thermal head  23  comprises a plurality of heating elements arranged in a direction orthogonal to the transport direction. This plurality of heating elements performs printing by forming dots on the respective printing lines of the cover film. Specifically, in response to the cover film being fed by the platen roller  24  and the printing lines of the cover film sequentially passing the positions of the heating elements, the conduction mode of the heating elements is sequentially switched on a per line print data (section of print data divided into one printing line unit) basis, based on the driving control of the thermal head driving circuit  61 . With this arrangement, it is possible for the thermal head  23  to perform printing at a printing speed that matches the feeding speed of the cover film by the platen roller  24 . In the example shown in  FIG. 7B , the printing of one line print data (“one dot” in the figure) is performed each time four pulse signals are input to the pulse motor  63   a.    
     Feeding and Printing Coordination 
     Hence, according to this embodiment, as shown in  FIG. 8A  and  FIG. 8B , two coordinated states are prepared as coordination modes when feeding and printing are performed in coordination as described above. 
     One is a first coordinated state wherein the conduction of the above described plurality of heating elements and the driving of the above described pulse motor are controlled in coordination (equivalent to “regular interval” in  FIG. 8A ). In this case, control is performed so that a pulse/dot ratio α (the ratio between the number of outputs of a pulse signal to the pulse motor  63   a  and the number of prints of the line print data) becomes a relatively large ratio (a first ratio α1; 4 pulses/one dot in this example; α1=4), in other words, so that one dot is printed each time the pulse motor  63   a  rotates in an amount equivalent to a relatively large phase by a relatively large number of pulses. As a result, the pulse motor  63   a  constantly rotates at a relatively fast rotation speed (hereinafter suitably referred to as “first rotation speed”). 
     The other is a second coordinated state for suppressing the print length so that it is shorter, wherein the conduction of the above described plurality of heating elements and the driving of the above described pulse motor  63   a  are controlled in coordination (equivalent to “print length correction interval” in  FIG. 8A ). In this case, control is performed so that the above described pulse/dot ratio α becomes a second ratio α2 (3 pulses/one dot in this example; α2=3) smaller than the above described first ratio α1, in other words, so that one dot is printed each time the pulse motor  63   a  rotates in an amount equivalent to a relatively small phase by a relatively small number of pulses. With this arrangement, the print length of the print length correction interval is equivalent to three-fourths that of the regular interval. Then, the pulse motor  63   a  constantly rotates at a relatively slow rotation speed (hereinafter suitably referred to as “second rotation speed”). 
     If there is a Large Difference in Pulse Motor Rotation Speeds 
     As described above, according to this embodiment, it is possible to switch between and execute the first coordinated state for achieving a regular print length and the second coordinated state for suppressing the print length. Nevertheless, the pulse motor  63   a  rotates at the relatively fast above described first rotation speed in the first coordinated state and conversely rotates at the relatively slow above described second rotation speed in the second coordinated state, as previously mentioned. As a result, when the conduction of the above described plurality of heating elements of the thermal head  23  and the driving of the above described pulse motor  63   a  are controlled in coordination as described above and the mode is switched from the first coordinated state to the second coordinated state or conversely from the second coordinated state to the first coordinated state, the possibility exists that the input of the pulse signal previously mentioned and the switching of the excitation phase will become mismatched as shown as a comparison example in  FIG. 9  if there is a large difference in the rotation speeds of the above described pulse motor  63   a , causing difficulties in smooth motor operation. 
     Gradual Decrease and Gradual Increase Control when Switching Coordinated States 
     Hence, in this embodiment, when the mode is switched from the first coordinated state to the second coordinated state, the conduction of the above described plurality of heating elements and the driving of the above described pulse motor  63   a  are controlled in coordination so that the pulse/dot ratio is gradually changed (gradually decreased) from the above described first ratio to the above described second ratio, as shown in  FIG. 10A . Further, similarly, when the mode is switched from the second coordinated state to the first coordinated state, the conduction of the above described plurality of heating elements and the driving of the above described pulse motor  63   a  are controlled in coordination so that the pulse/dot ratio is gradually changed (gradually increased) from the above described second ratio to the above described first ratio, as shown in  FIG. 10B . 
     Gradual Decrease/Gradual Increase Setting Details of Pulse Motor Rotation Speed 
     Specifically, according to this embodiment, the speed when the pulse motor  63   a  transitions from the regular interval to the print length correction interval (or the speed when the pulse motor  63   a  transitions (returns) from the print length correction interval to the regular speed decrease interval) is gradually increased (or decreased), as shown in  FIG. 11 . 
     That is, when the pulse motor  63   a  transitions to the print length correction interval, given Va (a constant speed) as the above described first rotation speed immediately prior to the transition and Vb (a constant speed) as the above described second rotation speed of the print length correction interval that is slower than the first rotation speed, the speed difference |Va−Vb| is changed in stages. In the example shown in  FIG. 11 , given “4,” for example, as a number of stages C and ΔV=|Va−Vb|/C as a change ΔV in speed, the speed is gradually decreased using a four-stage change ΔV with respect to the speed difference |Va−Vb|. That is, a first stage decreasing speed of the pulse motor  63   a  immediately after transition to the above described print length correction interval (refer to (a) in  FIG. 11 ) is Va−ΔV, a subsequent second stage decreasing speed (refer to (b) in  FIG. 11 ) is Va−2ΔV, a subsequent third stage decreasing speed (refer to (c) in  FIG. 11 ) is Va−Δ3V, and then a final fourth stage decreasing speed is Va−4ΔV (=Vb). As a result, in the print length correction intervals thereafter, the pulse motor  63   a  changes to a low constant speed operation based on the above described Vb. 
     That is, when the pulse motor  63   a  returns from the print length correction interval to the regular interval as well, the speed is gradually increased using the four-stage change ΔV with respect to the speed difference |Va−Vb|, similar to the above. That is, a first stage increasing speed of the pulse motor  63   a  immediately after the pulse motor  63   a  starts to return from the above described print length correction interval to the regular interval (refer to (d) in  FIG. 11 ) is Vb+ΔV, a subsequent second stage increasing speed (refer to (e) in  FIG. 11 ) is Vb+2ΔV, a subsequent third stage increasing speed (refer to (f) in  FIG. 11 ) is Vb+Δ3V, and then a final fourth stage increasing speed is Vb+4ΔV (=Va). As a result, in the regular intervals thereafter, the pulse motor  63   a  changes to a high constant speed operation based on the above described Va. 
     Note that while, in order to clarify the technique,  FIG. 11  describes an illustrative scenario of the above described gradual decrease control after the high constant speed operation of the above described first rotation speed Va is achieved immediately after the pulse motor  63   a  is accelerated (subject to through-up) from speed 0 at the start of printing operation, the gradual decrease control of this embodiment is not limited to this timing (refer to  FIG. 8A ). Similarly, while  FIG. 11  describes an illustrative scenario of the above described gradual increase control when the rotation speed returns from the above described second rotation speed Vb immediately before the pulse motor  63   a  is decelerated (subject to through-down) from the first rotation speed Va at the end of printing, the gradual increase control of this embodiment is not limited to this timing (refer to  FIG. 8A ). 
     Control Flow 
     The following describes the control procedure executed by the CPU  74  of the control circuit  70  for achieving the above described technique, using the flowcharts shown in  FIG. 12  and  FIG. 13 . 
     In  FIG. 12 , the flow is started by the generation of the corresponding above described print data based on a suitable operation and a suitable printing start instruction by the operator on the keyboard  5  of the label producing apparatus  1 , for example. First, in step S 10 , the CPU  74  outputs a control signal to the motor driving circuit  63  at the start of the printing operation and controls the pulse signal applied to the pulse motor  63   a , thereby setting the target speed of the pulse motor  63   a  to the above described first rotation speed Va. 
     Subsequently, in step S 20 , the CPU  74  determines whether or not the actual speed of the pulse motor  63   a  has reached the above described first rotation speed Va Immediately after printing is started and the pulse motor  63   a  starts rotation by the above described step S 10 , the actual speed has not reached the first rotation speed and therefore the condition of step S 20  is not satisfied (step S 20 : No) and the flow proceeds to step S 30 . 
     In step S 30 , the CPU  74  determines whether or not the timing is that at which the printing of the thermal head  23  ends, based on the above described print data. If the timing is immediately after printing has started as described above, the condition of step S 30  is not satisfied (step S 30 : No) and the flow proceeds to step S 50 . 
     In step S 50 , the CPU  74  executes the setup processing of the pulse/dot ratio α when the conduction of the plurality of heating elements and the driving of the pulse motor  63   a  are to be controlled in coordination (described in detail later using  FIG. 13 ). 
     Subsequently, in step S 60 , the CPU  74  executes the printing of one line based on the pulse/dot ratio α set in the above described step S 50 . That is, the CPU  74  outputs a control signal to the motor driving circuit  63  to apply a pulse signal to the pulse motor  63   a  at a cycle based on a preset pulse cycle and rotationally drive the pulse motor  63   a  in an amount equivalent to one pulse. As a result, the CPU  74  feeds the cover film in an amount equivalent to a predetermined distance corresponding to the printing of one line based on the above described pulse/dot ratio α. On the other hand, the CPU  74  outputs a control signal to the thermal head driving circuit  61  to supply electricity to the plurality of heating regions of the thermal head  23  at a cycle based on the preset above described pulse cycle and print one line corresponding to the line print data on the cover film. 
     As described later, the pulse/dot ratio α of regular intervals other than print length correction intervals is considered to be α=α1, a relatively large value. Accordingly, in the above described regular interval, the printing of the above described one line is executed on a per relatively large feeding distance basis. After the above described processing of step S 60 , the flow proceeds to step S 70 . 
     In step S 70 , the CPU  74  determines whether or not the printing of the total number of printing lines has ended on the cover film based on the above described print data and the like. Until the printing of the total number of lines ends, the condition is not satisfied (step S 70 : No), the flow returns to the above described step S 20 , and the procedure of step S 20  to step S 70  is repeated in the same manner as described above. 
     In such a repetition as described above, when a certain amount of time has elapsed after the start of rotation of the pulse motor  63   a  (in other words, after the start of printing) and the actual speed of the pulse motor  63   a  reaches the first rotation speed Va, the condition of the previously mentioned step S 20  is satisfied (step S 20 : Yes), and the flow proceeds to step S 80 . In step S 80 , the CPU  74  determines whether or not the pulse motor  63   a  is to transition to the print length correction interval (wherein the rotation speed of the pulse motor  63   a  is set to the above described second rotation speed Vb, which is slower than the above described first rotation speed Va), based on the above described print data. If the timing is not yet that at which the pulse motor  63   a  transitions to the print length correction interval, the condition of step S 80  is not satisfied (step S 80 : No), the flow returns to the above described step S 30 , and the same procedure as described above is thereafter repeated. 
     On the other hand, if the timing is that at which the pulse motor  63   a  is to transition to the above described print length correction interval based on the print data, the condition of the above described step S 80  is satisfied (step S 80 : Yes), and the flow proceeds to step S 90 . 
     In step S 90 , the CPU  74  outputs a control signal to the motor driving circuit  63  and controls the pulse signal applied to the pulse motor  63   a , thereby setting the target speed of the pulse motor  63   a  to the above described second rotation speed Vb corresponding to the print length correction interval. 
     Subsequently, in step S 100 , the CPU  74  determines whether or not the actual speed of the pulse motor  63   a  has reached the above described second rotation speed Vb (decreased to Vb). Immediately after transition to the above described print length correction interval is started, the pulse/dot ratio α is gradually decreased toward α2 in step S 50  described later, and corresponding deceleration is executed in step S 60 , the speed has not yet decreased to the second rotation speed and therefore the condition of step S 100  is not satisfied (step S 100 : No), the flow proceeds to step S 30 , and the same procedure as described above is thereafter repeated. Once the speed decrease gradually advances by step S 50  and step S 60  and the speed decreases to the second rotation speed due to the repetition, the condition of step S 100  is satisfied (step S 100 : Yes) and the flow proceeds to step S 110 . 
     In step S 110 , the CPU  74  determines whether or not the above described print length correction interval has ended and the pulse motor  63   a  is to return to the original regular interval, based on the above described print data. Immediately after the pulse motor  63   a  transitions to the above described print length correction interval, (the timing is not yet that at which the pulse motor  63   a  returns to the regular interval and therefore) the condition of step S 110  is not satisfied (step S 110 : No), the flow proceeds to step S 30 , and the same procedure as described above is thereafter repeated. Once the pulse motor  63   a  progresses through print length correction interval during the repetition and the timing is that at which the pulse motor  63   a  returns to the regular interval, the condition of step S 110  is satisfied (step S 110 : Yes), and the flow proceeds to step S 120 . 
     In step S 120 , the CPU  74  outputs a control signal to the motor driving circuit  63  and controls the pulse signal applied to the pulse motor  63   a , thereby setting the target speed of the pulse motor  63   a  to the above described first rotation speed Va corresponding to the original regular interval. Subsequently, the flow returns to the above described step S 30  and the same procedure as described above is thereafter repeated. 
     Then, the printing is continued by the above described repetition and, when the timing is that at which the printing of the thermal head  23  is to end (the end of printing is approaching) based on the print data, the condition of the previously mentioned step S 30  is satisfied (step S 30 : Yes) and the flow proceeds to step S 40 . 
     In step S 40 , the CPU  74  controls the pulse signal applied to the pulse motor  63   a  by the motor driving circuit  63  to set the target speed to “0.” Note that the processing content of the CPU  74  executed in this step S 40  and the above described step S 10  is equivalent to the third control described in the claims. In the subsequent step S 50  and thereafter, the same procedure as described above is repeated. Due to the repetition, the speed decrease gradually advances by step S 50  and step S 60  and the speed of the pulse motor  63   a  decreases toward a stop until the printing of the total number of lines ends based on the print data. 
     Then, when the above described motor speed decreases due to the above described repetition and the printing of the total number of lines (on the cover film) ends based on the print data, the condition of step S 70  is satisfied (step S 70 : Yes) and the flow is terminated. 
     Pulse/Dot Ratio Setup Processing 
     Next, the details of the pulse/dot ratio setup processing of step S 50  will be described using the flowchart of  FIG. 13 . 
     In  FIG. 13 , in step S 51 , the CPU  74  first sets the pulse/dot ratio α to the first ratio α1, which is a relatively large value corresponding to the previously mentioned regular interval. 
     Subsequently, in step S 52 , the CPU  74  determines whether or not the pulse motor  63   a  is to transition to the print length correction interval (wherein the rotation speed of the pulse motor  63   a  is set to the above described second rotation speed Vb, which is slower than the above described first rotation speed Va), based on the above described print data, similar to the above described step S 80 . 
     If the pulse motor  63   a  is to transition to the print length correction interval, the condition of step S 52  is satisfied (step S 52 : Yes) and the flow proceeds to step S 53 . If the pulse motor  63   a  is not to transition to the print length correction interval, the condition of step S 52  is not satisfied (step S 52 : No) and the flow proceeds to step S 55 . 
     In step S 53 , the CPU  74  determines whether or not the above described pulse/dot ratio α has reached the second ratio α2, which is a relatively small value corresponding to the previously mentioned print length correction interval. 
     Immediately after the pulse motor  63   a  transitions to the print length correction interval, the pulse/dot ratio α has not reached the second ratio α2 and therefore the condition of step S 53  is not satisfied (step S 53 : No), and the flow proceeds to step S 54 . In step S 54 , the CPU  74  decreases the pulse/dot ratio α in an amount equivalent to the speed change Δα, thereby gradually decreasing the motor rotation speed. In the previously mentioned example, ΔV=|Va−Vb|/C (C: Number of stages=4) and the speed is gradually decreased in four stages by ΔV. Subsequently, back to  FIG. 12 , the flow proceeds to step S 60  and the previously mentioned procedure is thereafter repeated. 
     When the pulse/dot ratio α decreases to the second ratio α2 due to the above described repetition, including the gradual decrease processing in the above described step S 54 , the condition of step S 53  is satisfied (step S 53 : Yes), the flow returns to the above described step S 60  of  FIG. 12  as is, and the same procedure as described above is thereafter repeated. Note that the processing content of the CPU  74  that proceeds to the step S 60  as is upon satisfaction of the condition of this step S 53  is equivalent to the second control described in the claims. 
     On the other hand, after such a transition to the print length correction interval, if the print length correction interval ends and the pulse motor  63   a  is to return to the regular interval, the condition of step S 52  is not satisfied (step S 52 : No), and the flow proceeds to step S 55 . 
     In step S 55 , the CPU  74  determines whether or not the pulse motor  63   a  is to return from the above described print length correction interval to the above described regular interval, based on the above described print data, similar to the above described step S 110 . 
     If the pulse motor  63   a  is to return to the regular interval, the condition of step S 55  is satisfied (step S 55 : Yes) and the flow proceeds to step S 56 . If the pulse motor  63   a  is not to return to the regular interval, the condition of step S 55  is not satisfied (step S 55 : No), the flow returns to the above described step S 60  of  FIG. 12  as is, and the same procedure as described above is thereafter repeated. Note that the processing content of the CPU  74  that proceeds to the step S 60  as is without satisfaction of the condition of this step S 55  is equivalent to the first control described in the claims. 
     In step S 56 , the CPU  74  determines whether or not the above described pulse/dot ratio α has reached the first ratio α1, which is a relatively large value corresponding to the previously mentioned regular interval. 
     Immediately after the pulse motor  63   a  starts to return from the print length correction interval to the regular interval, the pulse/dot ratio α has not reached the first ratio α1 and therefore the condition of step S 56  is not satisfied (step S 56 : No) and the flow proceeds to step S 57 . In step S 57 , the CPU  74  increases the pulse/dot ratio α in an amount equivalent to the speed change Δα, thereby gradually increasing the motor rotation speed. In the previously mentioned example, ΔV=|Va−Vb|/C (C: Number of stages=4) and the speed is gradually increased in four stages by ΔV. Subsequently, back to  FIG. 12 , the flow proceeds to step S 60  and the previously mentioned procedure is thereafter repeated. Note that the processing content of the CPU  74  in this step S 57  and the previously mentioned step S 54  is equivalent to the switching control described in the claims. 
     When the pulse/dot ratio α increases to the first ratio α1 due to the above described repetition, including the gradual increase processing in the above described step S 57 , the condition of step S 56  is satisfied (step S 56 : Yes), the flow returns to the above described step S 60  of  FIG. 12  as is, and the same procedure as described above is thereafter repeated. 
     Note that the present disclosure is not limited to the above described embodiment, and various modifications may be made without deviating from the spirit and scope of the disclosure. 
     (1) if the Second Rotation Speed is Revised Downward and Extension of the Total Operation Time is Prevented 
     That is, according to the above described embodiment, the pulse/dot ratio α gradually changes (rather than being immediately switched between α1 and α2) and the rotation speed of the pulse motor  63   a  is gradually decreased or gradually increased during the transition from the regular interval to the print length correction interval or during the transition from the print length correction interval to the regular interval. Nevertheless, as a result of performing such control, the overall total operation time when the mode is switched from the above described first coordinated state of the regular interval→the above described second coordinated state of the print length correction interval→the above described first coordinated state of the regular interval is extended compared to a case where the above are immediately switched (since the change in rotation speed of the pulse motor  63   a  slows down). 
     Hence, in this modification, as shown in  FIG. 14 , the above described second ratio α2 is corrected (to a smaller value than prior to correction, for example) so that the total operation time when the gradual decrease and gradual increase control of the rotation speed of the pulse motor  63   a  performed as described above is substantially the same as the total operation time when the above are immediately switched (without performing gradual decrease or gradual increase control). 
     That is, as shown in  FIG. 14 , a projected total operation time  2  (Va−Vb) which increases due to the gradual decrease and gradual increase in the above described technique is assigned to each remaining count d after constant speed is achieved (the second coordinated state), thereby revising the above described second rotation speed Vb downward to a lower speed Vb′ (note that this revision processing content of the CPU  74  is equivalent to the correction processing described in the claims). As a result, the behavior of the rotation speed of the pulse motor  63   a  during the transition to the print length correction interval becomes a transition from a first stage decreasing speed (Va−ΔV)→a second stage decreasing speed (Va−2ΔV)→a third stage decreasing speed (Va−Δ3V)→a fourth stage decreasing speed, that is, the above described second rotation speed Vb′ after revision (where Vb′&lt;Vb; refer to the dashed arrow in  FIG. 14 ). Similarly, the behavior of the rotation speed of the pulse motor  63   a  during return from the above described print length correction interval to the regular interval becomes a transition from the above described second rotation speed Vb′ after revision→a first stage increasing speed (Vb+ΔV)→a second stage increasing speed (Vb+2ΔV)→a third stage increasing speed (Vb+Δ3V)→a fourth stage increasing speed (Vb+4ΔV; equivalent to Va; refer to the dashed arrow in  FIG. 14 ). 
     Specifically, the above described speed Vb′ after revision is determined so that the total surface area of a triangular region (x) from the previously mentioned first stage decreasing speed Va′ (=Va−ΔV) to the rotation speed Vb′ of the print length correction interval and a triangular region (z) from the rotation speed Vb′ of the print length correction interval to the third stage increasing speed (equivalent to the above described Va′ in this example) in  FIG. 14  is equal to the surface area of the rectangular region (y) generated from the downward revision (from the rotation speed Vb prior to the above described revision) toward the above described rotation speed Vb′ when the pulse motor  63   a  is constantly rotated in the above described print length correction interval. That is, the speed Vb′ after revision is determined by the equation Vb′=Vb−4 (Va−Vb)/d. Hence, d is the number of pulses (pulse count) of the remaining intervals of the total number of pulses to be applied to the pulse motor  63   a  in the print length correction interval after subtracting the number of pulses (3+3=6 pulses in the above described example) used by the above described gradual decrease control and gradual increase control. 
     As a specific example, given Va=30, Vb=20, ΔV=2.5, and d=15, for example, then:
 
 Vb′= 20−4(30−20)/15
 
=20−2.666
 
=17.334
 
(2) Other
 
     Note that while the above has described an illustrative scenario in which the present disclosure is applied to a print label producing apparatus that performs desired printing on a print-receiving tape to produce a print label as the printer, the present disclosure is not limited thereto. That is, as printer examples, the present disclosure may be applied to a printer that forms an image and prints characters on regular print-receiving paper of a size such as A4, A3, B4, B5, or the like, or handheld printer driven by a battery power source. In this case as well, (if the model uses a pulse motor,) the same advantages are achieved. 
     Further, the arrows shown in the  FIG. 6  denote an example of signal flow, but the signal flow direction is not limited thereto. 
     Also note that the present disclosure is not limited to the steps shown in the above described flow of the flowcharts of  FIG. 12  and  FIG. 13 ; step additions and deletions as well as sequence changes may be made without deviating from the spirit and scope of the disclosure. 
     Further, other than that already stated above, techniques based on the above described embodiment may be suitably utilized in combination as well.