JP5560842B2 - Sublimation printer - Google Patents

Description

  The present invention relates to a sublimation printer capable of performing a thermal transfer printing process using a thermal head by driving a mechanism for transporting a printing object such as paper by a stepping motor, and particularly corrects the problem of density unevenness.

  2. Description of the Related Art Conventionally, a sublimation type printer that performs thermal transfer printing processing on a print object with a thermal head having a plurality of heating elements arranged in the width direction of the print object such as paper is known. This type of printer is configured to thermally transfer ink of an ink ribbon heated by a heating element to a printing object sandwiched between a thermal head and a platen in a state where the ink ribbon is overlapped. Yes.

  Here, a roller (for example, a feed roller) that forms a part of a transport mechanism that transports a printing object is supplied with an appropriate drive pulse signal (also referred to as a torque train) from a controller (control unit). It is comprised so that it may be rotationally driven by a motor (patent document 1). By using such a stepping motor, the conveyance speed of the printing object by the conveyance mechanism can be controlled with high accuracy.

JP 2009-240060 A

  However, in a printer provided with such a stepping motor, there is a tendency for density unevenness to occur at a predetermined pitch on a printing object subjected to printing processing.

  The present inventors pay attention to such a problem, and as a driving pulse signal input from the controller to the stepping motor after earnest research, the pulse width corresponding to the pulse On duration or one pulse On · Off A pulse period corresponding to time is fixed to a constant value, and it has been found that pulse control based on such a drive pulse signal, that is, fixed pulse control, causes density unevenness. The present inventors have devised a printer that can prevent / suppress the occurrence of density unevenness that may occur at a predetermined pitch by adopting pulse control different from fixed pulse control.

That is, the present invention relates to a thermal head, a transport mechanism that transports a printing object such as paper along a transport path, a stepping roller that drives at least one roller that is a part of the transport mechanism, and a drive pulse to the stepping motor. The present invention relates to a sublimation printer including a rotation drive control unit that outputs a signal and performs rotation drive control of the stepping roller. In the sublimation printer of the present invention, the rotation drive control unit calculates the number of pulses in one cycle corresponding to the density unevenness interval that appears on the print target subjected to the printing process at a constant cycle. A combination of a calculation means and a plurality of types of pulse periods including a variable pulse period obtained by adjusting a reference pulse period with a fluctuation rate within a predetermined range without changing the number of pulses in one cycle calculated by the pulse number calculation means And a pulse period variation means for generating a correction drive pulse signal constituting one cycle, and a drive pulse signal output means for outputting the correction drive pulse signal generated by the pulse period variation means to the stepping motor is applied. The pulse period variation means corrects with multiple types of varying pulse periods adjusted by changing to a different fluctuation rate from the fluctuation rate set for the first time. By enabling generates a dynamic pulse signal, and characterized by being configured so as to cope with the period of the driving vibration of a different stepping motor by individual differences of the sublimation type printer.

  Here, the “variable pulse period” in which the reference pulse period is adjusted with the fluctuation rate within a predetermined range includes a pulse period longer than the reference pulse period, a pulse period shorter than the reference pulse period, Both are included, and a pulse period whose period is equivalent to the reference pulse period as a result of adjustment with the variation rate within the predetermined displacement is also included. The “variation rate” can be set as appropriate within a range that does not cause step-out.

  As described above, in the sublimation printer of the present invention, the rotation drive control unit first calculates the number of pulses in one cycle by the pulse number calculation means, in other words, how many pulses the one cycle corresponds to the carry amount. And then a plurality of types of pulse periods including a variable pulse period obtained by adjusting a reference pulse period (hereinafter also referred to as a “reference pulse period”) with a fluctuation rate within a predetermined range by the pulse period changing unit. A correction drive pulse signal constituting one cycle is generated with one of the fluctuation pulse periods being equal to the reference pulse period, and the generated correction drive pulse signal is stepped by the drive pulse signal output means. Output to the motor. Therefore, the printer of the present invention controls the rotational drive of the stepping motor based on such a correction drive pulse signal.

  And when the present inventors drive the stepping motor based on the correction drive pulse signal composed of such a plurality of different variable pulse periods, density unevenness of a predetermined pitch does not occur on the print object, It was confirmed that occurrence of density unevenness at a predetermined pitch can be suppressed. Here, the operation and effect peculiar to the present invention that the occurrence of such density unevenness can be effectively prevented / suppressed is pulse control based on a correction drive pulse signal in which one cycle is composed of a plurality of different pulse periods, that is, fluctuations. Indefinite vibration occurs when the stepping motor is driven by pulse control, but the variable pulse period that causes such indefinite vibration cancels out the fixed pulse period that can cause density unevenness at a constant pitch. It is thought that it is obtained by. In the present invention, the number of pulses in one cycle in the corrected drive pulse signal generated by the pulse period varying means is set to be the same as the number of pulses in one cycle in the drive pulse signal before correction. It is possible to avoid a great hindrance to the object conveyance process, and to perform appropriate speed control of the stepping motor.

  In particular, in the sublimation printer of the present invention, when changing the pulse period by the pulse period changing means, the total pulse width when one cycle is configured with the reference pulse period without changing the number of pulses in one cycle. If it is set to generate a correction drive pulse signal in which the total pulse width when one cycle is composed of a plurality of different pulse periods (the ratio of the pulse duration in one cycle) is equal, Even under pulse control (fluctuation pulse control) based on the pulse period thus made, high accuracy of speed control, which is an inherent characteristic of a stepping motor, can be maintained and exhibited.

  According to the present invention, a new and useful technical idea is adopted in which a stepping motor is driven with a pulse period (variable pulse period) that cancels a pulse period that can generate density unevenness that can be displayed at a predetermined pitch on a print object. Accordingly, it is possible to provide a sublimation type printer that can prevent or suppress the occurrence of density unevenness and does not cause a decrease in print quality.

1 is a diagram illustrating a principal configuration principle of a sublimation printer according to an embodiment of the present invention. The figure which shows the drive pulse signal which commands fixed pulse control. The functional block diagram of the rotation drive control part in the embodiment. The figure which shows the correction | amendment drive pulse signal produced | generated by the rotation drive control part in the embodiment. 6 is a flowchart of density unevenness reduction processing by the sublimation printer according to the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the sublimation printer X according to the present embodiment includes a thermal head 1 that performs thermal transfer printing processing on a paper S that is a print target, a transport mechanism 2 that transports the paper S, and a transport mechanism 2. A stepping motor 3 that drives a part of the feed roller 22 and a control unit (not shown) that controls the operation of these units are provided.

  The thermal head 1 has a number of heating elements (not shown) arranged in one or a plurality of rows in the width direction of the paper S, and heat transfer printing processing is performed on the paper S by causing the heating elements to generate heat based on image data or the like. belongs to.

  The transport mechanism 2 includes a platen roller 21 that presses and sandwiches the paper S with the thermal head 1, and a feed roller 22 that is disposed upstream of the platen roller 21 in the paper transport direction (for example, the direction of arrow A in FIG. 1). And a set of the pinch roller 23 and a set of the feed roller 22 and the pinch roller 23 arranged downstream of the platen roller 21 in the sheet conveying direction A. Each pinch roller 23 can pinch the paper S between the feed roller 22 and the feed position where the paper S can be pinched between the feed rollers 22 facing each other and the feed roller 22 spaced apart from each feed roller 22 facing each other. It is provided so as to be movable between a non-clamping position (not shown). Each feed roller 22 can rotate in the forward and reverse directions and always rotates synchronously or substantially synchronously, and the platen roller 21 rotates in synchronization with or following the feed roller 22.

  As shown in FIG. 1, the printer X according to the present embodiment passes the ink ribbon 4 together with the paper S between the thermal head 1 and the platen roller 21, and heats the ink ribbon 4 with the thermal head 1. Is a so-called sublimation type printer X that is sublimated and transferred onto the paper S. The ink ribbon 4 is unwound from the supply-side ribbon core 41 and guided to the thermal head 1 side by the supply-side guide roller 42. After passing through the thermal head 1 in close contact with the paper S, the ink ribbon 4 is removed from the paper S by the peeling guide roller 43. It is a well-known one that is peeled off and wound around the winding-side ribbon core 44. In this embodiment in which the thermal transfer printing process is performed while transporting the paper S in the transport direction A, the supply-side ribbon core 41 and the supply-side guide roller 42 are arranged on the upstream side of the thermal head 1 in the paper transport direction A, and the peeling guide roller 43 and the take-up side ribbon core 44 are arranged downstream of the thermal head 1 in the paper transport direction A. If the thermal transfer printing process is performed while transporting the paper S in the return direction B, the supply-side ribbon core 41 and the supply-side guide roller 42 are disposed upstream of the thermal head 1 in the paper return direction B and are peeled off. The guide roller 43 and the take-up side ribbon core 44 are arranged downstream of the thermal head 1 in the paper return direction B.

  The stepping motor 3 drives the above-described feed rollers 22 to rotate synchronously. Although it is possible to adopt a mode in which each feed roller 22 is rotationally driven by a separate stepping motor 3, in this embodiment, each feed roller 22 is configured to be rotationally driven by a common stepping motor 3. doing. As shown in FIG. 1, the stepping motor 3 receives a drive pulse signal PS (drive pulse train) from a rotation drive control unit 5 that performs rotation drive control of the stepping motor 3. When the drive pulse signal PS as shown in FIG. 2 is input from the rotational drive control unit 5 to the stepping motor 3, for example, the stepping motor 3 has a pulse width PSt (pulse duration) associated with the drive pulse signal PS. The feed roller 22 is rotated by a predetermined angle while being repeatedly started and stopped according to time, and the feed rollers 22 are rotated directly or via a transmission mechanism (not shown) by an angle corresponding to the advance angle. The rotation drive control unit 5 that controls the rotation drive of the stepping motor 3 may constitute a part of the control unit described below, or may be provided separately from the control unit. Good.

  The control unit is configured by a CPU (not shown) connected so as to be communicable with each unit, and by this control unit, a region of the heating element to be energized among the heating elements arranged in the width direction in each thermal head 1 (energizing element) ), A paper S transport operation by the transport mechanism 2, a head up operation and a head down operation of each thermal head 1, a paper supply operation by a paper feed unit (not shown), a cutting operation by a cut unit, etc. The overall operation of X is controlled.

  In such a sublimation printer X, each feed roller 22 constituting the transport mechanism 2 is rotated in the same direction by the stepping motor 3 to feed each sheet S wound in a roll shape in a sheet feeding unit (not shown). When the paper is sent in the transport direction A while passing between the roller 22 and each pinch roller 23 at the sandwiching position, the heating element of the thermal head 1 is energized as appropriate, and the ink of the ink ribbon 4 is applied to the print area on the paper S. Can be thermal transfer printed. In this printer X, when the paper S is transported in the transport direction (paper S feed-out direction) A or the paper return direction B without performing the sublimation printing process by the thermal head 1, the thermal head 1 is connected to the platen roller 21. Thus, the paper S is kept in a position where the paper S cannot be sandwiched between them (head up position), and the paper S is smoothly conveyed.

  By the way, the drive pulse signal PS (drive pulse train) input from the rotation drive control unit 5 is usually referred to as a reference pulse cycle PSr (hereinafter referred to as “reference pulse cycle PSr”) as shown in FIG. ), And the pulse width PSt (pulse duration) in each reference pulse period PSr is also constant. When the printing process is performed by rotating the stepping motor 3 based on the drive pulse signal PS instructing the fixed pulse control in which the reference pulse period PSr and the pulse width PSt are fixed to the constant value, the sheet S is placed on the sheet S. Density unevenness occurred at a predetermined pitch.

  Therefore, the printer X according to the present embodiment uses the above-described fixed driving pulse signal PS to be input to the stepping motor 3 based on a density unevenness expression result obtained by a test print performed before, for example, product shipment. The drive pulse signal PS for instructing pulse control is corrected and changed to the drive pulse signal PS ′ for instructing fluctuation pulse control, so that density unevenness does not occur or hardly occurs in the next print processing.

  That is, the sublimation type printer X of the present invention has, as shown in FIG. 3, a rotation number control unit 5 that controls the rotation drive of the stepping motor 3, as shown in FIG. The one provided with the signal output means 53 is applied.

  The pulse number calculation means 51 calculates the number of pulses in one cycle corresponding to the density unevenness interval that appears on the paper S that has undergone the test print process in a fixed cycle. The term “one cycle” in the present invention means a time interval at which density unevenness is converted from the density unevenness interval (distance) that appears on the paper S at a constant period. Then, in the pulse number calculation means 51, one cycle corresponds to how many pulses the conveyance amount is based on the preset rotation speed of the stepping motor 3 (the conveyance speed of the paper S) and the time interval at which density unevenness occurs. The number of pulses in one cycle is calculated by determining whether to do this. Note that the density unevenness interval (distance) is input to the rotation drive control unit 5 from a system capable of automatic measurement processing using a measuring device or the like via an interface (not shown). Note that, for example, the density unevenness interval (distance) may be measured by an operation using a magnifying glass or an electron microscope, and may be input to the rotation drive control unit 5 by an appropriate means.

  The pulse period variation means 52 does not change the number of pulses in one cycle calculated by the pulse number calculation means 51, and includes a plurality of types of pulses including a variation pulse period in which the reference pulse period PSr is adjusted with a variation rate within a predetermined range. A correction drive pulse signal PS ′ constituting one cycle is generated by a combination of periods. Here, with reference to the drive pulse signal PS for instructing the fixed pulse control shown in FIG. 2, for example, the drive pulse signal PS ′ for instructing the fluctuation pulse control shown in FIG. Will be described. In FIG. 4, for the sake of convenience of explanation, a drive pulse signal PS before correction (fixed) is provided below a drive pulse signal PS ′ for instructing variable pulse control (hereinafter sometimes referred to as “corrected drive pulse signal PS ′”). A drive pulse signal PS for instructing pulse control is shown as a comparison target.

  Specifically, in the pulse cycle variation means 52, when the number of pulses in one cycle in the drive pulse signal PS before correction is, for example, “3”, the number of pulses in one cycle in the correction drive pulse signal PS ′ is corrected. Is set to “3”, which is the same number as the drive pulse signal PS, and when the variation rate is “α”, one cycle is equivalent to the reference pulse cycle PSr, which is a pulse cycle PSx (this pulse cycle is also a kind of variable pulse cycle) And a fluctuation pulse period PSy corresponding to “reference pulse period PSr + α%” and a fluctuation pulse period PSz corresponding to “reference pulse period PSr−variation rate α%”. A correction driving pulse signal PS ′ is generated in which the ratio of the pulse width PSt in the pulse period is set to be equal or substantially equal. Further, the total pulse width in one cycle in the correction drive pulse signal PS 'is set to be substantially or substantially the same as the total pulse width in one cycle before the pulse period fluctuation.

  The drive pulse signal output means 53 outputs the corrected drive pulse signal PS ′ generated by the pulse cycle varying means 52 to the stepping motor 3. The drive pulse signal output means 53 may also serve as an output means for outputting the drive pulse signal PS to the stepping motor 3 before the pulse period is changed.

  Next, a method and an action for preventing / reducing density unevenness in the printer X according to the present embodiment will be described.

  First, a test print process is performed, for example, before the product is shipped. Then, the interval of density unevenness appearing on the paper S at a predetermined pitch is measured from the test print processing result (density unevenness interval measuring step S1, see FIG. 5). As described above, the density unevenness interval is preferably measured by an automatic measurement process using a measuring device or the like.

  Next, the printer X of the present embodiment calculates the number of pulses in one cycle corresponding to the density unevenness interval by the pulse number calculation means 51 (pulse number calculation step S2, see FIG. 5). Then, the pulse period changing means 52 has the same number as the number of pulses in one cycle and the reference pulse period PSr is adjusted by the fluctuation rate (α) within a predetermined range. A correction drive pulse signal PS ′ constituting one cycle is generated by the combination (pulse period variation step S3, see FIG. 5). Subsequently, the printer X outputs the generated correction drive pulse signal PS 'to the stepping motor 3 from the rotation drive control unit 5 by the drive pulse signal output means 53 (drive pulse signal output step S4, see FIG. 5).

  According to the above procedure, the printer X according to the present embodiment operates the transport mechanism 2 while controlling the rotational drive of the stepping motor 3 based on the correction drive pulse signal PS ′ input from the rotational drive control unit 5 to perform the thermal operation. The printing process by the head 1 is performed again.

  In this print processing, the vibration of the stepping motor 3 that is driven and controlled by the variable pulse control becomes indefinite, and density unevenness on the paper S can be prevented and suppressed from occurring at a predetermined pitch. If the occurrence of density unevenness at a predetermined pitch has been improved, it is possible to prevent or suppress the occurrence of density unevenness at a predetermined pitch even in subsequent print processing, resulting in a decrease in print processing quality due to density unevenness. Therefore, it is possible to provide a sublimation type printer X having excellent practicality.

  As described above, when the sublimation printer X according to the present embodiment drives the stepping motor 3 based on the correction drive pulse signal PS ′ that constitutes one cycle from a plurality of different variable pulse periods PSx, PSy, PSz, It is possible to prevent the density unevenness of the predetermined pitch from occurring on the paper S or to suppress the density unevenness of the predetermined pitch. This is because indefinite vibration occurs when the stepping motor 3 is driven by pulse control based on the correction drive pulse signal PS ′ constituted by a plurality of different pulse periods in one cycle, that is, variable pulse control. It is inferred that the variable pulse period that causes indefinite vibration is obtained by canceling the fixed pulse period that can cause density unevenness at a constant pitch.

  Further, the sublimation printer X of the present embodiment uses the number of pulses in one cycle in the corrected drive pulse signal PS ′ generated by the pulse period changing means 52 as the number of pulses in one cycle in the drive pulse signal PS before correction. Since the same number is set, it is possible to avoid a large influence on the conveyance process of the sheet S, and it is possible to perform appropriate speed control of the stepping motor 3.

  In particular, in the sublimation type printer X of the present embodiment, when the pulse period is changed by the pulse period changing means 52, the number of pulses in one cycle is not changed, and one cycle is configured with the reference pulse period PSr. The correction drive pulse signal PS ′ is generated so that the total pulse width (ratio of the pulse duration in one cycle) is equal to the total pulse width when one cycle is composed of a plurality of different pulse periods. Therefore, it is possible to maintain and demonstrate the high accuracy of speed control, which is an original characteristic of the stepping motor 3, under pulse control (fluctuating pulse control) with a varied pulse period.

Further, if there is a case where density unevenness generation at a predetermined pitch is not improved even after performing the print processing based on the correction drive pulse signal PS ′ generated by the first pulse cycle variation processing, the pulse cycle variation means 52 If a correction driving pulse signal PS ′ constituting one cycle is generated by a plurality of types of fluctuation pulse periods adjusted at a fluctuation rate different from the first fluctuation rate, and a print process is performed based on the correction driving pulse signal PS ′. Good. In particular, since the period of the driving vibration of the stepping motor varies depending on the individual difference of the printer X, the variation rate is not fixed, for example, by configuring the variation rate to be adjustable in the maintenance mode at the time of printer production, It is possible to flexibly cope with all driving vibrations having individual differences for each printer X.

  In addition, this invention is not limited to embodiment mentioned above. For example, in the above-described embodiment, the mode in which the roller driven by the stepping motor is the feed roller is exemplified. However, instead of or in addition to the feed roller, another roller (for example, a platen roller) constituting the transport mechanism is used as the stepping motor. It can also be configured to drive.

  Further, the variation rate used when adjusting the reference pulse cycle can be appropriately set and changed within a range that does not cause step-out.

  Further, it may be a multi-head type printer in which a plurality of print units including thermal heads are arranged along the transport direction. In this case, each print unit can be set with an ink ribbon in which different color inks are applied to the ribbon, and the thermal transfer printing process can be sequentially performed on the print surface of the paper conveyed in a predetermined direction.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Thermal head 2 ... Conveyance mechanism 22 ... Roller (feed roller)
DESCRIPTION OF SYMBOLS 3 ... Stepping motor 5 ... Rotation drive control part 51 ... Pulse number calculation means 52 ... Pulse period fluctuation | variation means 53 ... Drive pulse signal output means S ... Print target object (paper)
X ... Sublimation printer

Claims (2)

A thermal head, a transport mechanism that transports a print object along a transport path, a stepping motor that drives at least one roller that is part of the transport mechanism, and a drive pulse signal that is output to the stepping motor A sublimation type printer having a rotation drive control unit for performing rotation drive control of a stepping motor,
The rotational drive control unit is
A pulse number calculating means for calculating the number of pulses in one cycle corresponding to the interval of density unevenness that appears on the print target subjected to the printing process at a constant cycle;
One cycle is a combination of a plurality of types of pulse periods including a variable pulse period that is the same as the number of pulses in one cycle calculated by the pulse number calculation means and that is obtained by adjusting a reference pulse period with a fluctuation rate within a predetermined range. Pulse period variation means for generating a correction drive pulse signal constituting
All SANYO with a drive pulse signal output means for outputting a correction driving pulse signal generated by the pulse period fluctuation means to said stepping motor,
The pulse period variation means can generate the correction drive pulse signal with a plurality of types of variation pulse periods adjusted by changing to a variation rate different from the variation rate set for the first time. A sublimation type printer configured to be able to cope with a period of driving vibration of the stepping motor which varies depending on individual differences . The correction driving pulse is adjusted so that the total pulse width in one cycle constituted by a plurality of types of pulse periods is equal to the total pulse width in one cycle before the pulse period fluctuation. The sublimation printer according to claim 1, which generates a signal.

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