Patent ID: 12251948

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Below, the present embodiment will be described with reference to the drawings.

FIG.1is a diagram illustrating one example of the entire configuration of a label printer1according to the present embodiment.

The label printer1is, for example, a printer of an ink jet type configured to perform printing of characters, images, diagrams, or the like using a label sheet P as a printing medium.

The label printer1corresponds to one example of a “printing apparatus”.

The label sheet P includes a base sheet Pa and a plurality of labels Pb. The base sheet Pa is a band-shaped continuous sheet. The front surface of the base sheet Pa has a peeling property, and the labels Pb each cut into a predetermined size are affixed at equal intervals in the longitudinal direction of the base sheet Pa. The materials of the base sheet Pa and the labels Pb may be paper, or may be a material other than paper. The label sheet P is mounted at the label printer1as roll paper R wound in a roll form.

The label printer1includes a printing unit3serving as a main body of the label printer1, and a peeling unit4. The peeling unit4may be formed integrally with the printing unit3or may be a component detachable from the printing unit3.

The peeling unit4is a device configured such that a process of peeling the labels Pb from the base sheet Pa is performed to the label sheet P on which printing has been performed by the printing unit3, and hence, is called a peeler. The label printer1is able to perform a non-peeling mode for ejecting a label sheet P in which the label Pb is still attached on the base sheet Pa after printing has been performed, and also able to perform a peeling mode for ejecting a label Pb that has been peeled from the base sheet Pa after printing has been performed. In the present embodiment, the peeling mode will be described.

The printing unit3uses a printing head8to perform printing to each of the labels Pb of the label sheet P on the basis of a command and print data transmitted from a not-illustrated computer. In addition, the printing unit3transports the label sheet P along a transport path of the label sheet P. Below, the upstream and the downstream in the transport path may be simply referred to as “upstream” and “downstream”, respectively.

As illustrated inFIG.1, the printing unit3includes an accommodation portion29, a delivering roller10, a first roller11, a platen12, a guide13, the printing head8, and a control unit40.

The accommodation portion29is a space used to accommodate the roll paper R, and the label sheet P is delivered from the roll paper R mounted at the accommodation portion29. The delivering roller10is comprised of a pair of rollers disposed so as to be opposed to each other, and is configured to transport downstream the label sheet P delivered from the roll paper R.

The first roller11is comprised of a pair of rollers disposed so as to be opposed to each other, and is configured to interpose the label sheet P transported by the delivering roller10to transport it downstream toward the printing head8.

The delivering roller10is coupled to a feed motor that is not illustrated, and rotates with power of the feed motor. The first roller11is coupled directly to the first motor M1or through a gear, a belt, or the like, and rotates with power of the first motor M1.

The first motor M1corresponds to one example of a “first driving unit”.

The first roller11and the first motor M1will be described in more detail with reference toFIGS.2and3.

The platen12is disposed downstream of the first roller11in the transport path of the label sheet P. A platen surface12athat is an upper surface of the platen12is brought into contact with the base sheet Pa of the label sheet P to support the label sheet P from below. The platen surface12aincludes a plurality of suction holes (not illustrated). Each of the suction holes communicates with a suction fan that is not illustrated. With the suction fan operating, air is suctioned from the suction holes to suck the label sheet P at the platen surface12a.

The printing head8is disposed so as to be opposed to the platen surface12a. The printing head8includes nozzle rows, which are not illustrated, each corresponding to ink of one or a plurality of colors, and discharges ink from nozzles that constitute each of the nozzle rows. The printing head8discharges ink to the label Pb disposed on the platen surface12aon the basis of the print data to perform printing on the label Pb. The label sheet P on which printing has been performed by the printing head8is transported, by the first roller11, to the peeling unit4at the downstream side.

The present embodiment describes a case in which the label printer1is of ink jet type to perform printing on the label Pb. However, the type thereof is not limited to the ink jet type.

The guide13is disposed downstream of the printing head8. Between the platen12and the peeling unit4, the guide13supports, from below, the label sheet P on which printing has been performed by the printing head8. The label sheet P passes above the guide13, and is transported toward the peeling unit4downstream.

The peeling unit4includes a peeling member30and a second roller31. The peeling member30is disposed downstream of the guide13of the printing unit3. The peeling member30includes a guide surface30athat is brought into contact with the base sheet Pa of the label sheet P to support the label sheet P from below, and a peeling edge30bformed at the top end of the guide surface30aand having an acute angle. The label sheet P guided by the guide13is transported to above the guide surface30aof the peeling member30.

The second roller31is comprised of a pair of rollers disposed so as to be opposed to each other, and is configured to interpose the base sheet Pa to transport it. The second roller31is coupled directly to the second motor M2or through a gear, a belt, or the like, and rotates with power of the second motor M2.

The second motor M2corresponds to one example of a “second driving unit”.

The second roller31and the second motor M2will be described in more detail with reference toFIGS.2and3.

When the label printer1is operated in the peeling mode, a user performs an operation of interposing the base sheet Pa of the label sheet P at the second roller31before the start of printing. The second roller31is disposed at a position lower than the peeling member30, and interposes the base sheet Pa to transport it with the base sheet facing downward. The base sheet Pa of the label sheet P that is transported through the guide surface30ais bent at the peeling edge30b, and is pulled downward by the second roller31. With this pulling force by the second roller31, the label Pb is lifted from the base sheet Pa at the peeling edge30b, and is peeled off. The peeled label Pb protrudes toward the left direction from the peeling unit4inFIG.1. The label Pb protruding from the peeling unit4is collected by the user. On the other hand, the base sheet Pa transported by the second roller31toward a direction differing from that of the label Pb is ejected downward of the second roller31.

In the configuration described above, the delivering roller10, the first roller11, the platen12, the guide13, and the guide surface30aof the peeling member30constitutes the transport path of the label sheet P in the printing unit3. In addition, the peeling edge30band the second roller31constitutes a portion of the transport path of the base sheet Pa.

The control unit40controls operations of each component that constitutes the label printer1. In the present embodiment, the control unit40controls driving of the first roller11and the second roller31. That is, the control unit40controls the first motor M1and the second motor M2.

The control unit40will be described in more detail with reference toFIGS.2and3.

Next, a method of driving the first roller11and a method of driving the second roller31will be described with reference toFIGS.2and3.

FIG.2is a diagram illustrating one example of the configuration of the main components of the label printer1.FIG.3is a diagram illustrating one example of the configuration of the control unit40.

As illustrated inFIG.2, the first roller11includes a first driving roller11aand a first driven roller11b, and the label sheet P is interposed between them. The first motor M1rotationally drives the first driving roller11a. The first driven roller11bis supported so as to be able to rotate in association with transportation of the label sheet P due to rotation of the first driving roller11a.

The second roller31includes a second driving roller31aand a second driven roller31b, and the base sheet Pa of the label sheet P is interposed between them. The second motor M2rotationally drives the second driving roller31a. The second driven roller31bis supported so as to be able to rotate in association with transportation of the base sheet Pa due to rotation of the second driving roller31a.

At the first roller11, the first driven roller11bpresses the first driving roller11awith force F1in order to interpose the label sheet P. In other words, the first driving roller11ais pressed with the force F1in a direction substantially perpendicular to the direction of the label sheet P at a contact point with the label sheet P.

The front surface of the first driving roller11ais formed by thermal spraying or subjected to powder coating. In this case, a friction coefficient μ1between the first driving roller11aand the label sheet P is a value large enough for the label sheet P not to slip relative to the front surface of the first driving roller11a. The front surface of the first driven roller11bis made, for example, of rubber.

Tension TP is tension applied to the label sheet P between the first roller11and the second roller31. The tension TP satisfies the following Relationship (1).
TP<μ1×F1  (1)

The control unit40controls driving of the first motor M1to control the tension TP. For example, the control unit40controls the generated torque TE1generated by the first motor M1such that the tension TP is equal to a tension target value TT.

The present embodiment describes a case in which the tension target value TT is a constant value. In this case, the control unit40controls a load torque TL1applied from the label sheet P to the first roller11, so as to be equal to a target torque TS corresponding to the tension target value TT. That is, the control unit40controls the generated torque TE1generated by the first motor M1such that the load torque TL1is the target torque TS that is a constant value.

Note that the tension target value TT is set to a value that does not cause the label sheet P to loosen or bend between the first roller11and the second roller31.

The process of the control unit40will be described in more detail with reference toFIG.3.

At the second roller31, the second driven roller31bpresses the second driving roller31awith force F3in order to interpose the base sheet Pa. In other words, the second driving roller31ais pressed by the second driven roller31bwith the force F3in a direction substantially perpendicular to the advancing direction of the base sheet Pa at a contact point with the base sheet Pa. A friction coefficient p3is a friction coefficient between the second driving roller31aand the base sheet Pa.

The front surface of the second driving roller31ais formed by thermal spraying or subjected to powder coating. In this case, a friction coefficient p3between the second driving roller31aand the base sheet Pa is a value large enough for the base sheet Pa not to slip relative to the front surface of the second driving roller31a. The front surface of the second driven roller31bis made, for example, of rubber.

The tension TP is tension applied to the base sheet Pa between the first roller11and the second roller31. The tension TP satisfies the following Relationship (2).
TP<μ3×F3  (2)

The control unit40controls driving of the second motor M2such that a transport velocity VP of the base sheet Pa is equal to a target transport velocity VT. The target transport velocity VT varies, for example, in a substantially trapezoid shape, and the target transport velocity VT corresponding to a rotational angle φ of the second driving roller31ais stored in a table.

For example, the target transport velocity VT is set to zero during a time when the printing head8performs printing on the label sheet P, and during a period of time from a time when the label Pb reaches a peeling position PP where the label Pb protrudes from the peeling unit4to a time when the label Pb is collected by a user.

In addition, after printing to the label sheet P finishes, the target transport velocity VT is set so as to accelerate at a constant acceleration, keep a constant velocity, and decelerate at a constant acceleration. Thus, driving of the second motor M2is controlled such that the transport velocity VP accelerates at a constant acceleration, is maintained at a constant velocity, and decelerates at a constant acceleration, thereby causing the label Pb to be transported to the peeling position PP.

The target transport velocity VT corresponds to one example of a “predetermined velocity”.

Next, the configuration of the control unit40will be described with reference toFIG.3.

As illustrated inFIG.3, a rotational angle θ of the first driving roller11ais inputted from the first rotary encoder11cinto the control unit40, and a rotational angle φ of the second driving roller31ais inputted from the second rotary encoder31cinto the control unit40.

The first rotary encoder11cis disposed, for example, at an end portion, in the width direction, of the first driving roller11a, and is configured to detect the rotational angle θ of the first driving roller11a. The first rotary encoder11coutputs a detection signal indicating the rotational angle θ to the control unit40.

The present embodiment describes a case in which the first rotary encoder11cis disposed at the first driving roller11a. However, the configuration is not limited to this. The first rotary encoder11cmay be disposed at the first motor M1to detect the rotational angle of the driving shaft of the first motor M1.

The second rotary encoder31cis disposed, for example, at an end portion, in the width direction, of the second driving roller31a, and is configured to detect the rotational angle φ of the second driving roller31a. The second rotary encoder31coutputs a detection signal indicating the rotational angle φ to the control unit40.

The present embodiment describes a case in which the second rotary encoder31cis disposed at the second driving roller31a. However, the configuration is not limited to this. The second rotary encoder31cmay be disposed at the second motor M2to detect the rotational angle of the driving shaft of the second motor M2.

The control unit40controls a first voltage V1applied to the first motor M1. In addition, the control unit40controls a second voltage V2applied to the second motor M2.

Note that the present embodiment describes a case in which the control unit40controls the first voltage V1and the second voltage V2. However, the configuration is not limited to this. The control unit40may control the first voltage V1and the second voltage V2through a voltage control circuit.

The control unit40includes a processor40A and a memory40B.

The memory40B is a storage device configured to store, in a nonvolatile manner, data or a program executed by the processor40A. The memory40B is comprised of a magnetic storage device, a semiconductor storage element such as a flash read only memory (ROM), or other types of nonvolatile storage device. In addition, the memory40B may include a random access memory (RAM) that constitutes the work area of the processor40A. Furthermore, the memory40B may include a nonvolatile storage device such as a hard disk drive (HDD), a solid state drive (SSD), or the like.

The memory40B stores data to be processed by the control unit40or a control program43to be executed by the processor40A.

The processor40A may be configured as a single processor or may be configured such that a plurality of processors function as the processor40A.

The control unit40may be configured, for example, with an integrated circuit. The integrated circuit includes an LSI, an application specific integrated circuit (ASIC), and a programmable logic device (PLD). The PLD includes, for example, a field-programmable gate array (FPGA). In addition, a portion of the configuration of the integrated circuit may include an analog circuit, and it may be possible to employ a combination of a processor and an integrated circuit. The combination of a processor and an integrated circuit is called a micro-controller (MCU), a system-on-a-chip (SoC), a system LSI, a chip set, or the like.

The control unit40functionally includes a first-motor control unit41and a second-motor control unit42. Specifically, the processor40A reads the control program43stored in the memory40B to execute it, thereby functioning as the first-motor control unit41and the second-motor control unit42.

The first-motor control unit41adjusts the first voltage V1applied to the first motor M1on the basis of information about the transport velocity and the transport acceleration of the label sheet P, such that the load torque TL1of the first motor M1is the target torque TS.

The target torque TS corresponds to one example of a “predetermined value”.

The information about the transport velocity and the transport acceleration of the label sheet P includes, for example, an angular velocity ω1and an angular acceleration α1of rotation at the first roller11.

The angular velocity ω1can be expressed as the following Equation (3).
ω1=dθ/dt(3)

That is, the angular velocity ω1can be obtained by differentiating the rotational angle θ with respect to the time t.

The angular acceleration α1can be expressed as the following Equation (4).
α1=d2θ/dt2(4)

That is, the angular acceleration α1can be obtained by differentiating, twice, the rotational angle θ with respect to the time t. In other words, the angular acceleration α1can be obtained by differentiating the angular velocity ω1with respect to the time t.

Note that, below, description will be made of a case in which the rotational speed of the first motor M1and the rotational speed of the first roller11are equal to each other, for the purpose of convenience. That is, description will be made of a so-called case in which the speed reduction ratio is “1”. In addition, description will be made of a case in which the first motor M1is a direct current motor.

The following Equation (5) shows a relationship between a first voltage V1(t) applied to the first motor M1and a current I1(t) flowing through the first motor M1.

[Equation⁢1]V⁢1⁢(t)=R⁢1×I⁢1⁢(t)+L⁢1⁢dI⁢1⁢(t)dt+K⁢1×ω⁢1(5)

Here, the constant R1represents a resistance value of the first motor M1. The constant L1represents an inductance of the first motor M1. The constant K1represents a torque constant of the first motor M1, that is, a back electromotive force constant.

The period required for the current I1to reach a stationary value is significantly short as compared with the period required for the angular velocity ω1(=dθ1/dt) to reach a stationary value. Thus, in the present embodiment, it is assumed that the term concerning a change in time of the current I1(t), that is, the second term at the right-hand side of the Equation (5) is zero. Thus, the following Equation (6) can be obtained.
V1(t)=R1×I1(t)+K1×ω1  (6)

The generated torque TE1generated by the first motor M1can be obtained using the following Equation (7).
TE1=K1×I1(t)  (7)

The equation of motion of the first motor M1can be expressed in the following Equation (8).
TM1=J1×α1+C1×ω1  (8)

Here, the load torque TM1represents a load torque of the first motor M1. The constant J1represents a moment of inertia of the first motor M1. The constant C1represents a viscous load of the first motor M1.

The generated torque TE1generated by the first motor M1can be obtained through the following Equation (9) by using the load torque TM1of the first motor M1.
TE1=TM1+TL1  (9)

Here, the load torque TL1indicates a load torque applied to the first motor M1from the label sheet P.

By using Equation (6), the current I1(t) of Equation (7) is removed; Equation (8) and the equation obtained by removing the current I1(t) from Equation (7) are substituted into Equation (9) to work it out in terms of the first voltage V1(t), whereby it is possible to obtain the following Equation (10).

[Equation⁢2]V⁢1⁢(t)=J⁢1×R⁢1K⁢1⁢α⁢1+(K⁢1+c⁢1×R⁢1K⁢1)⁢ω⁢1+R⁢1K⁢1⁢TL⁢1(10)

The first-motor control unit41adjusts the first voltage V1applied to the first motor M1so as to be the first voltage V1obtained using the Equation (10) such that the load torque TL1of the first motor M1is a predetermined value.

In the present embodiment, the first-motor control unit41controls the load torque TL1so as to be equal to the target torque TS that is a constant value. That is, the first-motor control unit41adjusts the first voltage V1applied to the first motor M1so as to be the first voltage V1obtained using Equation (10), such that the load torque TL1is equal to the target torque TS that is a constant value. By controlling the first voltage V1applied to the first motor M1in this manner, it is possible to control the tension TP to be equal to the tension target value TT.

In other words, on the basis of the angular velocity ω1and the angular acceleration α1of rotation at the first roller11, the first-motor control unit41controls the first voltage V1applied to the first motor M1using Equation (10), thereby being able to control the tension TP to be equal to the tension target value TT.

The second-motor control unit42performs feedback control of the second voltage V2applied to the second motor M2on the basis of information about the rotational angle φ of the second driving roller31aand the transport velocity VP of the base sheet Pa, such that the transport velocity VP of the base sheet Pa is a predetermined velocity. The information about the transport velocity VP of the base sheet Pa is an angular velocity ω2of rotation of the second roller31. The relationship between the transport velocity VP of the base sheet Pa and the angular velocity ω2of rotation of the second roller31can be expressed as the following Equation (11).
VP=R2×ω2  (11)

Here, the constant R2indicates a radius of the second roller31.

On the other hand, the following Equation (12) can be obtained as with Equation (6) described above.
V2(t)=R2×I2(t)+K2×ω2  (12)

Here, the constant R2indicates a resistance value of the second motor M2. The constant K2indicates a torque constant of the second motor M2, that is, a back electromotive force constant.

In addition, a generated torque TE2generated by the second motor M2is expressed as the following Equation (13).
TE2=K2×I2(t)  (13)

For example, when the generated torque TE2generated by the second motor M2is a constant value, the current I1(t) flowing through the first motor M1in Equation (12) is removed by using Equation (13), whereby it is possible to obtain the following Equation (14).
V2(t)=R2×TE2/K2+K2×ω2  (14)

That is, in order to increase the angular velocity ω2of rotation of the second roller31, it is only necessary to increase the second voltage V2applied to the second motor M2. In addition, in order to reduce the angular velocity ω2of rotation of the second roller31, it is only necessary to reduce the second voltage V2applied to the second motor M2. In other words, it is possible to control the transport velocity VP by using the second voltage V2as the amount of control.

The second-motor control unit42calculates the angular velocity ω2of the second roller31on the basis of the rotational angle φ of the second roller31, and uses Equation (11) to calculate an actually measured value VQ of the transport velocity VP. Furthermore, calculation is perform to obtain a difference ΔV between the target transport velocity VT corresponding to the rotational angle φ of the second roller31and the actually measured value VQ of the transport velocity VP, and feedback control, for example, PID control is performed to the second voltage V2applied to the second motor M2as the amount of control such that the difference ΔV is zero.

In this manner, the second-motor control unit42controls the transport velocity VP so as to be the target transport velocity VT.

Next, with reference toFIG.4, description will be made of a specific example of operation of the first-motor control unit41.FIG.4includes graphs each showing one example of the angular velocity ω1, the first voltage V1, and the load torque TL1concerning the first motor M1.FIG.4shows results of simulation of the angular velocity ω1, the first voltage V1, and the load torque TL1concerning the first motor M1.

The graph of the angular velocity ω1is shown in the upper section ofFIG.4. The graph of the first voltage V1is shown in the middle section ofFIG.4. The graph of the load torque TL1is shown in the lower section ofFIG.4.

In the graph shown in the upper section ofFIG.4, the vertical axis indicates the angular velocity ω1, and the horizontal axis indicates the time t.

The graph G1indicates changes in the angular velocity ω1.FIG.4illustrates a case in which the angular velocity ω1changes, for example, in a shape of a waveform obtained by rectifying a current in a form of sine wave into a form of half-wave, as illustrated by the graph G1. For example, as for the angular velocity ω1, during a period of time when the time t is from 0 to 0.025 sec, the angular velocity ω1increases from 0 to 1900 rpm. Furthermore, the angular velocity ω1reduces from 1900 rpm to 0 rpm during a period of time when the time t is from 0.025 sec to 0.05 sec. The angular velocity ω1is kept at 0 during a period of time when the time t is from 0.05 sec to 0.1 sec.

In the graph shown in the middle section ofFIG.4, the vertical axis indicates the first voltage V1, and the horizontal axis indicates the time t. The graph G2indicates changes in the first voltage V1. Note that the first voltage V1is controlled by the first-motor control unit41on the basis of Equation (10) described above.

As illustrated in the graph G2, the first voltage V1is kept at −12 V during a period of time in which the angular velocity ω1is kept at 0, for example, during a period of time when the time t is from 0.05 sec to 0.1 sec. That is, during this period of time, the first motor M1causes the first roller11to be driven in the negative direction. The negative direction represents a direction in which the roll paper R is driven in a direction opposite to the advancing direction.

The first voltage V1increases from −12 V to 1.22 V during a period of time when the time t is from 0 sec to 0.018 sec. In addition, the first voltage V1reduces from 1.22 V to −15.53 V during a period of time when the time t is from 0.018 sec to 0.043 sec. In addition, during a period of time when the time t is from 0.043 sec to 0.05 sec, the first voltage V1increases from −15.53 V to −12 V. That is, when the first motor M1accelerates, the first voltage V1increases due to the moment of inertia of the first motor M1and the viscous load of the first motor M1. When the first motor M1decelerates, the first voltage V1reduces due to the moment of inertia of the first motor M1whereas the first voltage V1increases due to the viscous load of the first motor M1.

In the graph shown in the lower section ofFIG.4, the vertical axis indicates the load torque TL1, and the horizontal axis indicates the time t.

In the graph G3, the load torque TL1is kept at a substantially constant value, that is, at −0.02 Nm. A negative value of the load torque TL1indicates that the first motor M1receives a load in the advancing direction of the label sheet P due to the tension TP applied to the label sheet P between the first roller11and the second roller31.

As described above with reference toFIG.4, the first-motor control unit41controls the first voltage V1on the basis of Equation (10) described above, whereby it is possible to keep the load torque TL1at a substantially constant value even when the angular velocity ω1of the first motor M1changes.

Next, processes of the control unit40will be described with reference toFIGS.5and6.FIG.5is a flowchart showing one example of control of the first motor M1by the first-motor control unit41.

Note thatFIG.5illustrates a case in which the load torque TL1is set in advance to the target torque TS that is a constant value, such that the tension TP is the tension target value TT.

First, in step S101, the first-motor control unit41acquires the rotational angle θ of the first driving roller11afrom the first rotary encoder11c, as illustrated inFIG.5. Next, in step S103, the first-motor control unit41calculates the angular velocity ω1of the first driving roller11aby differentiating the rotational angle θ with respect to the time t.

Next, in step S105, the first-motor control unit41calculates the angular acceleration α1of the first driving roller11aby differentiating the angular velocity ω1with respect to the time t.

Next, in step S107, the first-motor control unit41substitutes the load torque TL1, the angular velocity ω1, and the angular acceleration α1into Equation (10) described above to calculate the first voltage V1.

Then, in step S109, the first-motor control unit41adjusts the first voltage V1applied to the first motor M1so as to be the calculated first voltage V1. Then, the process returns to step S101.

Step S107and step S109correspond to one example of a “first step”.

In this manner, the first-motor control unit41adjusts the first voltage V1applied to the first motor M1to be the first voltage V1calculated using Equation (10) described above. This makes it possible to control the tension TP so as to be equal to a tension target value TT1.

FIG.6is a flowchart showing one example of control of the second motor M2by the second-motor control unit42.

First, in step S201, the second-motor control unit42acquires the rotational angle φ of the second driving roller31afrom the second rotary encoder31c, as illustrated inFIG.6. Next, in step S203, the second-motor control unit42differentiates the rotational angle φ with respect to time t to calculate the angular velocity ω2of the second driving roller31a.

Next, in step S205, the second-motor control unit42calculates the actually measured value VQ of the transport velocity VP of the base sheet Pa on the basis of the calculated velocity ω2.

After this, in step S207, the second-motor control unit42calculates a difference ΔV between the calculated actually measured value VQ of the transport velocity VP and the target transport velocity VT corresponding to the rotational angle φ.

Next, in step S209, the second-motor control unit42performs PID control to the second voltage V2applied to the second motor M2as the amount of control, such that the difference ΔV is zero. After this, the process returns to step S201.

Step S207and step S209correspond to one example of a “second step”.

In this manner, the second-motor control unit42performs PID control of the second voltage V2applied to the second motor M2as the amount of control, such that the difference ΔV between the actually measured value VQ of the transport velocity VP and the target transport velocity VT is zero. This enables the second-motor control unit42to control the transport velocity VP so as to be equal to the target transport velocity VT.

As described above with reference toFIGS.1to6, the label printer1according to the present embodiment includes: the printing head8configured to perform printing on the label sheet P in which the label Pb is attached at the base sheet Pa; the peeling unit4configured to peel the label Pb from the base sheet Pa; the first roller11disposed upstream of the peeling unit4in the transport path of the label sheet P; the second roller31disposed downstream of the peeling unit4in the transport path of the base sheet Pa; the first motor M1configured to drive the first roller11; the second motor M2configured to drive the second roller31; and the control unit40configured to control the first motor M1and the second motor M2, in which the control unit40includes: the first-motor control unit41configured to adjust the first voltage V1applied to the first motor M1on the basis of information about the transport velocity VP and the transport acceleration of the label sheet P such that the load torque TL1of the first motor M1is the target torque TS; and the second-motor control unit42configured to perform feedback control of the second voltage V2applied to the second motor M2on the basis of information concerning the transport velocity VP of the base sheet Pa such that the transport velocity VP of the base sheet Pa is the target transport velocity VT.

With this configuration, the first-motor control unit41adjusts the first voltage V1applied to the first motor M1on the basis of information about the transport velocity VP and the transport acceleration of the label sheet P, such that the load torque TL1of the first motor M1is the target torque TS. This makes it possible to control the load torque TL1of the first motor M1so as to be the target torque TS. Thus, it is possible to appropriately control the tension TP between the first roller11and the second roller31so as to be equal to the tension target value TT.

In addition, the second-motor control unit42performs feedback control of the second voltage V2applied to the second motor M2on the basis of the information about the transport velocity VP of the base sheet Pa, such that the transport velocity VP of the base sheet Pa is the target transport velocity VT. This makes it possible to appropriately control the transport velocity VP of the base sheet Pa so as to be the target transport velocity VT.

In addition, in the label printer1according to the present embodiment, the information about the transport velocity VP and the transport acceleration of the label sheet P includes the angular velocity ω1and the angular acceleration α1of rotation of the first roller11.

With this configuration, the first-motor control unit41adjusts the first voltage V1applied to the first motor M1on the basis of the angular velocity ω1and the angular acceleration α1of rotation of the first roller11. This makes it possible to appropriately control the load torque TL1of the first motor M1so as to be the target torque TS.

In addition, the label printer1according to the present embodiment, the information about the transport velocity PV of the base sheet Pa includes the angular velocity ω2of rotation of the second roller31.

With this configuration, the second-motor control unit42performs feedback control of the second voltage V2applied to the second motor M2on the basis of the angular velocity ω2of rotation of the second roller31. This makes it possible to appropriately control the transport velocity VP of the base sheet Pa so as to be the target transport velocity VT.

In addition, in the label printer1according to the present embodiment, the first-motor control unit41adjusts the first voltage V1applied to the first motor M1using Equation (A), such that the load torque TL1of the first motor M1so as to be the target torque TS.

[Equation⁢3]V⁢1⁢(t)=J⁢1×R⁢1K⁢1⁢α⁢1+(K⁢1+c⁢1×R⁢1K⁢1)⁢ω⁢1+R⁢1K⁢1⁢TL⁢1(A)

Here, the V1(t) on the left-hand side represents a voltage applied to the first motor M1. In addition, the α1on the right-hand side represents an angular acceleration of the first roller11. The ω1represents an angular velocity of the first roller11. The TL1represents a load torque of the first motor M1.

With this configuration, it is possible to appropriately control the first voltage V1applied to the first motor M1such that the load torque TL1of the first motor M1is the target torque TS.

In addition, in the label printer1according to the present embodiment, the front surface of each of the first roller11and the second roller31is formed by thermal spraying or subjected to powder coating.

With this configuration, it is possible to suppress occurrence of slip relative to the front surface of the first roller11of the label sheet P. In addition, this makes it possible to suppress occurrence of slip relative to the front surface of the second roller31of the base sheet Pa.

The method of controlling the label printer1according to the present embodiment provides a method of controlling driving control of the label printer1including: the printing head8configured to perform printing on the label sheet P in which the label Pb is attached at the base sheet Pa; the peeling unit4configured to peel the label Pb from the base sheet Pa; the first roller11disposed upstream of the peeling unit4in a transport path of the label sheet P; the second roller31disposed downstream of the peeling unit4in a transport path of the base sheet Pa; the first motor M1configured to drive the first roller11; the second motor M2configured to drive the second roller31; the control unit40configured to control the first motor M1and the second motor M2, the method including: a first step including adjusting, by the control unit40, the first voltage V1applied to the first motor M1on the basis of information about the transport velocity VP and the transport acceleration of the label sheet P, such that the load torque TL1of the first motor M1is the target torque TS; and a second step including performing, by the control unit40, feedback control of the second voltage V2applied to the second motor M2on the basis of information about the transport velocity VP of the base sheet Pa, such that the transport velocity VP of the base sheet Pa is the target transport velocity VT.

Thus, the method of controlling a label printer1according to the present embodiment provides an effect similar to the label printer1according to the present embodiment.

Note that, the present embodiment merely represents one aspect of the present disclosure, and any modification and application may be possible within the scope of the present disclosure.

For example, description has been made of a case in which the first driving unit according to the present embodiment is the first motor M1. However, the configuration is not limited to this. The first driving unit may include a voltage control circuit configured to control the first voltage V1supplied to the first motor M1.

In addition, for example, description has been made of a case in which the second driving unit according to the present embodiment is the second motor M2. However, the configuration is not limited to this. The second driving unit may include a voltage control circuit configured to control the second voltage V2supplied to the second motor M2.

The present embodiment describes a case in which the target torque TS is a constant value. However, the target torque TS is not limited to this. For example, it may be possible to employ a mode in which the target torque TS is determined according to the size of the label sheet P.

Furthermore, each functional component illustrated inFIG.3shows the functional configuration, and there is no particular limitation as to the specific implementation mode. In other words, it is not necessary to install hardware that individually corresponds to each of the functional component, and it may be possible to employ a configuration in which a single processor executes a program to achieve functions of a plurality of functional units. Furthermore, a portion of the functions achieved by software in the embodiment described above may be achieved by hardware. Alternatively, a portion of the functions achieved by hardware may be achieved by software. In addition, specific individual configurations of individual components of the label printer1can be changed as appropriate without departing from the scope of the present disclosure.

In addition, for example, units of processing in the flowcharts inFIGS.5and6are divided according to main processing details for the purpose of facilitating understanding the process of the control unit40, and the present disclosure should not be limited by the way of dividing the units of processing or names of units of processing. It may be possible to make further division into more units of processing depending on the processing details. Furthermore, it may be possible to make division such that one processing unit include more processes. In addition, the order of the processes may be changed on an as-necessary basis within an extent in which it does not affect the main point.

Furthermore, the method of controlling a label printer1can be achieved by causing the processor40A included in the control unit40to execute the control program43stored in the memory40B. In addition, the control program43can be recorded in a recording medium in a computer readable manner.

As for the recording medium, it is possible to use a magnetic or optical recording medium, or a semiconductor memory device. Specifically, the recording medium described above may include a portable or fixed recording medium, such as a flexible disk, a hard disk drive (HDD), a compact disk read only memory (CD-ROM), a digital versatile disk (DVD), a Blu-ray (registered trademark) disc, a magneto-optical disk, a flash memory, or a card-type recording medium.

In addition, the recording medium may be a non-volatile storage device such as a RAM, a ROM, or an HDD that is an internal storage device included in the label printer1. Furthermore, the functional blocks of the control unit40of the label printer1can be achieved by causing the control program43to be stored in a server device or the like and downloading the control program43from the server device to the control unit40of the label printer1.