Printer, control method, and storage medium

Abstract

To provide a printer, a control method, and a program capable of suppressing variation in a movement amount after stop.SOLUTION: In a printer, a thermal head performs printing on a medium. The conveyance motor is a DC motor. The platen roller is driven by rotation of the conveyance motor, and conveys the medium while sandwiching the medium between the platen roller and the thermal head. The electronic governor circuit supplies a current to the conveyance motor while the ON signal is input, and stops the supply of power to the conveyance motor while the OFF signal is input. The CPU outputs an ON signal or an OFF signal to the electronic governor circuit. A CPU outputs an ON signal to an electronic governing circuit to rotate a carrying motor at a first speed V1 when carrying media. When stopping the conveyance of the media, the CPU executes deceleration processing for alternately switching output of an ON signal and output of an OFF signal so that the conveyance motor rotates at the second speed V2. After continuing the deceleration processing for a predetermined period, the CPU outputs an OFF signal to the electronic governor circuit.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a printer, a control method, and a program. [Background technology]

[0002] The tape writer described in Patent Document 1 includes a DC motor, a driver circuit, and a tape motor control unit. The DC motor rotates when power is supplied, driving a platen roller and feeding the surface tape. The driver circuit supplies power to the DC motor and has a non-stable voltage supply circuit. The non-stable voltage supply circuit includes a transistor that turns the power supply to the DC motor on and off. The tape motor control unit outputs a control signal to the driver circuit to control the rotation of the DC motor. When stopping the surface tape, which is running at a constant speed, the driver circuit uses chopping control to intermittently turn the power supply to the DC motor on and off. As a result, the running speed of the surface tape gradually decreases, and then the surface tape stops. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-33080 Summary of the Invention [Problem to be solved by the invention]

[0004] When the platen roller is driven by the rotation of the DC motor to feed the tape, strain energy accumulates in the platen roller. Therefore, even when the rotation of the DC motor stops, the surface tape does not immediately stop being fed, but is fed a certain distance due to the accumulated strain energy. Hereinafter, the distance fed by strain energy is referred to as the post-stop movement distance. The post-stop movement distance and its variation increase in proportion to the surface tape feed speed before the DC motor stops. When printing on the surface tape is temporarily stopped and then resumed, a gap in the printing, i.e., a white line, may occur between the last line printed when printing stopped and the first line printed when printing resumes. This white line is more likely to occur when there is a large variation in the post-stop movement distance. However, conventional tape writers do not sufficiently consider reducing the variation in the post-stop movement distance.

[0005] An object of the present invention is to provide a printer, a control method, and a program that can suppress variations in the amount of movement after stopping. [Means for solving the problem]

[0006] A printer according to a first aspect of the present invention comprises a thermal head having a plurality of heat generating elements for printing on a medium, a DC motor, a platen roller driven by the rotation of the DC motor and sandwiching the medium between the thermal head and the platen roller for transporting the medium, a motor drive unit that supplies current to the DC motor while an ON signal is input and stops the supply of current to the DC motor while an OFF signal is input, and a control unit that outputs the ON signal or the OFF signal to the motor drive unit and controls the motor drive unit, wherein the control unit performs the following operations when transporting the medium: a constant speed process that outputs the ON signal to the motor drive unit to rotate the DC motor at a first speed; a deceleration process that alternately switches between outputting the ON signal and outputting the OFF signal so that the DC motor rotates at a second speed that is slower than the first speed when transporting the medium being transported; and a stop process that outputs the OFF signal after continuing the deceleration process for a predetermined period of time.

[0007] According to a first aspect, while printing is being performed on a medium, the printer outputs an ON signal to the motor drive unit to rotate the DC motor at a first speed. When stopping printing, the printer executes a deceleration process. During the deceleration process, the control unit alternately outputs an ON signal and an OFF signal to the motor drive unit so that the DC motor rotates at a second speed. In this way, the printer performs pseudo-PWM control, and the DC motor rotates at a second speed that is slower than the first speed. The printer continues the deceleration process for a predetermined period and then stops. This reduces the strain energy accumulated in the platen roller during the stopping process. Therefore, compared to stopping the medium from the first speed, the printer reduces the post-stop movement amount, thereby suppressing variation in the post-stop movement amount.

[0008] A control method according to a second aspect of the present invention is a control method for a printer including a thermal head having a plurality of heating elements for printing on a medium, a DC motor, a platen roller driven by the rotation of the DC motor and sandwiching the medium between the thermal head and the platen roller for transporting the medium, a motor drive unit that supplies current to the DC motor while an ON signal is input and stops supplying the current to the DC motor while an OFF signal is input, and a control unit that outputs the ON signal or the OFF signal to the motor drive unit and controls the motor drive unit, wherein the control method executes the following steps when transporting the medium: a constant speed step of outputting the ON signal to the motor drive unit to rotate the DC motor at a first speed; a deceleration step of alternately switching between outputting the ON signal and outputting the OFF signal so that the DC motor rotates at a second speed that is slower than the first speed when transporting the medium being transported; and a stop step of continuing the deceleration step for a predetermined period and then outputting the OFF signal.

[0009] A program according to a third aspect of the present invention is a program to be executed by a computer that controls a printer including: a thermal head having a plurality of heating elements that prints on a medium; a DC motor; a platen roller that is driven by the rotation of the DC motor and that transports the medium by sandwiching it between the thermal head and the DC motor; a motor drive unit that supplies current to the DC motor while an ON signal is input and stops the supply of current to the DC motor while an OFF signal is input; and a control unit that outputs the ON signal or the OFF signal to the motor drive unit and controls the motor drive unit, and is characterized in that the program causes the computer to execute: a constant speed step in which, when transporting the medium, the ON signal is output to the motor drive unit to rotate the DC motor at a first speed; a deceleration step in which, when transporting the medium being transported, the output of the ON signal and the output of the OFF signal are alternately switched so that the DC motor rotates at a second speed that is slower than the first speed; and a stop step in which the deceleration step continues for a predetermined period and then the OFF signal is output.

[0010] The second and third aspects have the same effects as the first aspect. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view of the printer 1 as seen from above and to the right. [Figure 2] 3A and 3B are diagrams illustrating the configuration of the mounting section 8. FIG. [Figure 3] 2 is a block diagram showing the electrical configuration of the printer 1. FIG. [Figure 4] 1 is a diagram showing a schematic configuration of a thermal head 10. FIG. [Figure 5] 10 is a timing diagram of the rotation speed of the carry motor 24 and the motor signal output by the CPU 91 when the deceleration process is not performed. FIG. [Figure 6] 10 is a timing diagram of the rotation speed of the carry motor 24 and the motor signal output by the CPU 91 when deceleration processing is performed. FIG. [Figure 7]10 is a timing diagram of the transport amount of the medium 50, the rotation speed of the transport motor 24, and signals sent and received by the CPU 91 when deceleration processing is not performed. [Figure 8] 10 is a timing diagram of the transport amount of the medium 50, the rotation speed of the transport motor 24, and signals sent and received by the CPU 91 when deceleration processing is performed. [Figure 9] FIG. 10 is a conceptual diagram showing a table 99. [Figure 10] 10 is a flowchart of a main process. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present invention will be described below with reference to the drawings. The drawings are used to explain technical features that may be employed by the present invention. The device configurations shown in the drawings are merely illustrative examples and are not intended to be limiting. Hereinafter, the upper left, lower right, lower left, upper right, lower, and upper in FIG. 1 will be referred to as the left, right, front, rear, lower, and upper of the printer 1, respectively.

[0013] The configuration of printer 1 will be described with reference to Figure 1. Printer 1 is a thermal printer that uses a thermal head 10 to print on medium 50. Medium 50 is a long strip of thermal tape. Printer 1 has a housing 3. Housing 3 is a box whose depth is longer than it is wide. An operation unit 2, a display 5, and a cover 6 are provided on the top surface of housing 3. Operation unit 2 is provided at the front of the top surface of housing 3 and accepts user input operations. Display 5 is provided in the center of the top surface of housing 3 in the front-to-rear direction and displays various information. Cover 6 is provided at the rear of the top surface of housing 3. A support shaft (not shown) is provided on cover 6. The support shaft extends left and right from the rear end of cover 6. Cover 6 can be opened and closed freely, with the support shaft as the center of rotation.

[0014] An attachment section 8 is provided at the rear of the housing 3. With the cover 6 open, the tape cassette 30 is attached to and detached from the attachment section 8 in the vertical direction. The upper left, lower right, lower left, upper right, lower, and upper sides of the tape cassette 30 correspond to the left, right, front, rear, lower, and upper sides of the printer 1, respectively. The tape cassette 30 has a case 39 and an indicator section 31.

[0015] The case 39 of the tape cassette 30 is a box whose width is longer than its depth. The medium 50 is wound and stored in the case 39. In the mounting section 8, the width direction of the medium 50 is the vertical direction. The indicator portion 31 is provided on the front wall 33 of the case 39. The indicator portion 31 includes at least one hole portion 32. The indicator portion 31 indicates the type of medium 50 based on the position of each hole portion 32 in the front wall 33. The type of medium 50 is determined by, for example, the material, color, and width of the medium 50. Hereinafter, information indicating the type of medium 50 will be referred to as type information.

[0016] As shown in FIG. 2, the mounting unit 8 is provided with a detection unit 19 (see FIG. 3), a thermal head 10, a conveyance motor 24, a drive shaft (not shown), a platen roller 14, and a cutter unit 11.

[0017] The detection unit 19 includes a plurality of detection switches. When the tape cassette 30 is loaded into the loading portion 8, the plurality of detection switches are selectively pressed by the indicator portion 31. The detection unit 19 receives type information based on the ON / OFF combination of the detection switches, and the CPU 91, which will be described later, detects the type information based on the ON / OFF combination of the detection switches.

[0018] The thermal head 10 is a plate-like member extending in the left-right direction and includes a plurality of heating elements 110. The heating elements 110 contact the medium 50 from behind. The thermal head 10 selectively causes the heating elements 110 to generate heat to print on the medium 50. The detailed configuration of the thermal head 10 will be described later.

[0019] The transport motor 24 is a DC motor, and is connected to the drive shaft and platen roller 14 via a gear train (not shown). The drive shaft is driven by the rotation of the transport motor 24, and feeds out the medium 50 from the tape cassette 30. The platen roller 14 is made of, for example, rubber, and is elastic. The platen roller 14 contacts the front of the medium 50, and sandwiches the medium 50 between itself and the thermal head 10. The platen roller 14 is cylindrical with a rotation axis that extends vertically, and can rotate around the rotation axis. The platen roller 14 is driven by the rotation of the transport motor 24, and transports the medium 50 to the left.

[0020] The cutter unit 11 includes a cutting motor 23 (see FIG. 3), a movable blade 12, and a receiving table 13. The cutting motor 23 is, for example, a stepping motor, and is connected to the movable blade 12. The movable blade 12 is provided to the left of the platen roller 14 and is positioned in front of the medium 50. The movable blade 12 is movable back and forth and is driven by the rotation of the cutting motor 23.

[0021] The receiving base 13 is located to the left of the thermal head 10 and is aligned with the movable blade 12 in the front-to-rear direction. The receiving base 13 is a plate-like member extending in the left-to-right direction and comes into contact with the medium 50 from behind. The cutter unit 11 moves the movable blade 12 forward as the cutting motor 23 rotates, and the movable blade 12 cuts the medium 50 between the receiving base 13 and the movable blade 12. The cut medium 50 is discharged from the housing 3 through an outlet (not shown). The outlet is located at the left end of the rear of the housing 3.

[0022] The electrical configuration of the printer 1 will be described with reference to Figure 3. The printer 1 has a CPU 91, ROM 92, RAM 93, a storage unit 94, an electronic governor circuit 81, and drivers 82 to 84. The CPU 91 controls the printer 1 and functions as a control unit. The CPU 91 is connected to the ROM 92, RAM 93, storage unit 94, electronic governor circuit 81, encoder 240, drivers 82 to 84, thermal head 10, operation unit 2, and detection unit 19.

[0023] The ROM 92 stores a control program for executing a main process (see FIG. 10) described later and various setting information. The RAM 93 temporarily stores various information. The storage unit 94 is nonvolatile and stores a table 99 (see FIG. 9) described later and the like.

[0024] The electronic governor circuit 81 supplies current to the carry motor 24 based on a signal input from the CPU 91. An ON signal or an OFF signal is input to the electronic governor circuit 81 from the CPU 91. While the electronic governor circuit 81 receives an ON signal from the CPU 91, it supplies current to the carry motor 24 while controlling the voltage supplied to the carry motor 24 so that the carry motor 24 rotates at a first speed V1. While the electronic governor circuit 81 receives an OFF signal from the CPU 91, it stops supplying power to the carry motor 24. No signals other than the ON signal and the OFF signal are input to the electronic governor circuit 81. Hereinafter, the ON signal and the OFF signal will be collectively referred to as the motor signal.

[0025] The encoder 240 is a rotary encoder connected to the output shaft of the carry motor 24, and outputs a pulse signal corresponding to the rotation of the output shaft of the carry motor 24 to the CPU 91. Hereinafter, the rotation of the output shaft of the carry motor 24 will be referred to as the rotation of the carry motor 24. The CPU 91 detects the rotation speed of the carry motor 24 based on the time interval at which the pulse signal is input.

[0026] The driver 83 rotates the cutting motor 23 based on the control signal input from the CPU 91. The driver 84 displays an image on the display 5 based on the control signal input from the CPU 91.

[0027] The drive control of the thermal head 10 will be described with reference to Figure 4. In Figure 4, thick lines indicate power lines and thin lines indicate signal lines. The driver 82 connects the power supply 20 of the printer 1 and the multiple heating elements 110 via power lines. The driver 82 is connected to the SWVHON terminal of the CPU 91 via a signal line. The driver 82 supplies current from the power supply 20 to the multiple heating elements 110 based on a control signal input from the CPU 91.

[0028] The thermal head 10 includes a plurality of heating elements 110, a plurality of transistors 63, a shift register 61, and a latch driver 62. The collector of each transistor 63 is connected to the other end of each heating element 110. The emitter of each transistor 63 is grounded.

[0029] The shift register 61 is connected to the DATA terminal and CLK terminal of the CPU 91. Serial data representing print data is input to the shift register 61 from the DATA terminal. A clock signal is input to the shift register 61 from the CLK terminal. The shift register 61 includes multiple stages of flip-flops. The shift register 61 shifts the input serial data via the flip-flops.

[0030] The latch driver 62 is connected to the STB terminal and LAT terminal of the CPU 91. A strobe signal is input to the latch driver 62 from the STB terminal. A latch signal is input to the latch driver 62 from the LAT terminal. The latch driver 62 has multiple base terminals and multiple signal output terminals. A base terminal and a signal output terminal form a pair. Each base terminal is connected to the shift register 61. Each signal output terminal is connected to the base of a transistor 63.

[0031] When serial data indicating print data is input from the CPU 91, the shift register 61 shifts the serial data in synchronization with the clock signal input from the CPU 91. The latch driver 62 temporarily holds the serial data output from the shift register 61 in response to a latch signal input from the CPU 91.

[0032] The CPU 91 inputs a strobe signal to the latch driver 62 in synchronization with the interval at which the pulse signal is input from the encoder 240. While the strobe signal is being input, the latch driver 62 turns on the transistor 63 based on the retained serial data. This causes the multiple heating elements 110 to selectively generate heat, printing one line of an image corresponding to the print data on the medium 50. The printer 1 prints the image corresponding to the print data on the medium 50 by repeatedly printing one line while transporting the medium 50 with the platen roller 14.

[0033] 5 and 6, the control of feeding the medium 50 and stopping feeding of the medium 50 will be described. As shown in Fig. 5, when feeding the medium 50, the CPU 91 outputs an ON signal to the electronic governor circuit 81. When the ON signal is input, the electronic governor circuit 81 supplies current to the carry motor 24 while controlling the voltage supplied to the carry motor 24 so that the carry motor 24 rotates at the first speed V1. As a result, the carry motor 24 rotates at the first speed V1.

[0034] The platen roller 14 is driven by the rotation of the transport motor 24, and transports the medium 50 sandwiched between it and the thermal head 10. Therefore, while the platen roller 14 transports the medium 50, it is distorted by the reaction force it receives from the medium 50, and strain energy accumulates in the platen roller 14. The strain energy varies depending on the type of medium 50 and the rotation speed of the transport motor 24.

[0035] When the CPU 91 stops the medium 50, it outputs an OFF signal to the electronic governor circuit 81. From the time the CPU 91 outputs an ON signal at time 0 until it outputs an OFF signal at time T11, the medium 50 is transported by a length L11. The length L11 is derived by integrating the first speed V1 of the transport motor 24 over time from time 0 to time T11.

[0036] When the OFF signal is input, the electronic governor circuit 81 stops supplying current to the carry motor 24. The carry motor 24 begins to decelerate from the first speed V1 at time T11 and stops rotating at time T12. The carry motor 24 rotates by inertia from time T11 to time T12, and the platen roller 14 continues to transport the medium 50 from time T11 to time T12. The medium 50 is transported a length L12 from time T11 to time T12. Length L12 is derived by integrating the rotational speed of the carry motor 24 over time from time T11 to time T12.

[0037] The strain energy accumulated in the platen roller 14 is gradually released after the conveyance motor 24 begins to decelerate at time T11. The release of the strain energy causes the platen roller 14 to rotate by the amount of strain that the platen roller 14 has distorted. Therefore, the medium 50 continues to move even after the conveyance motor 24 stops at time T12. The amount of movement of the medium 50 after the conveyance motor 24 stops is called the post-stop movement amount dL. The post-stop movement amount dL varies depending on the magnitude of the strain energy. In other words, the post-stop movement amount dL varies depending on the type of medium 50 and the rotational speed of the conveyance motor 24.

[0038] The transport distance L1 of the medium 50 from when transport begins at time 0 until the medium 50 completely stops is the sum of length L11, length L12, and post-stop movement distance dL1 (L1 = L11 + L12 + dL1). The post-stop movement distance dL varies depending on various factors, such as the type of medium 50 and the rotational speed of the transport motor 24, as well as the temperature of the platen roller 14, the temperature of the medium 50, and the humidity around the printer 1, which can cause variation in the transport distance L1 of the medium 50. The variation in the post-stop movement distance dL varies depending on the magnitude of the post-stop movement distance dL. Therefore, by reducing the magnitude of the post-stop movement distance dL, the variation in the post-stop movement distance dL and the variation in the transport distance L1 also decrease.

[0039] The lower the rotational speed of the conveyance motor 24, the smaller the strain energy accumulated in the platen roller 14. As shown in FIG. 6, in the printer 1, after rotating the conveyance motor 24 at the first speed V1 from time 0, the conveyance motor 24 is set to the second speed V2 at time T21. The second speed V2 is smaller than the first speed V1 (V2 < V1). The printer 1 rotates the conveyance motor 24 at the second speed V2 until time T22. From time 0 to time T21, the medium 50 is conveyed by a length L21, and from time T21 to time T22, the medium 50 is conveyed by a length L22. The length L21 is derived by time-integrating the rotational speed of the conveyance motor 24 from time 0 to time T21, and the length L22 is derived by time-integrating the rotational speed of the conveyance motor 24 from time T21 to time T22.

[0040] The CPU 91 outputs an OFF signal to the electronic governor circuit 81 at time T22. The conveyance motor 24 starts decelerating from time T22 and stops at time T23. From time T22 to time T23, the medium 50 is conveyed by a length L23. The length L23 is derived by time-integrating the rotational speed of the conveyance motor 24 from time T22 to time T23. The magnitude of the post-stop movement amount dL is dL2. The conveyance amount L2 of the medium 50 is the sum of the length L21, the length L22, the length L23, and the post-stop movement amount dL2 (L2 = L21 + L22 + L23 + dL2).

[0041] A part of the strain energy accumulated in the platen roller 14 while the medium 50 is being conveyed at the first speed V1 is released while the medium 50 is being conveyed at the second speed V2. Therefore, the strain energy accumulated in the platen roller 14 at time T22 is smaller than the strain energy accumulated in the platen roller 14 at time T21. Thus, the post-stop movement amount dL2 shown in FIG. 6 is smaller than the post-stop movement amount dL1 shown in FIG. 5. The variation in the post-stop movement amount dL2 is smaller than the variation in the post-stop movement amount dL1.

[0042] 6, in the printer 1, the CPU 91 alternately switches the motor signal output to the electronic governor circuit 81 between an ON signal and an OFF signal. The electronic governor circuit 81 is a circuit for controlling the carry motor 24 so that it rotates at a constant speed. When an ON signal is input to the electronic governor circuit 81, the electronic governor circuit 81 controls the carry motor 24 to rotate at a first speed V1. When an OFF signal is input to the electronic governor circuit 81, the electronic governor circuit 81 stops the rotation of the carry motor 24. It takes time dT for the rotation speed of the carry motor 24 to reach the first speed V1 after an ON signal is input to the electronic governor circuit 81. Therefore, by having the CPU 91 switch between outputting an ON signal and an OFF signal to the electronic governor circuit 81 at a cycle shorter than time dT, the carry motor 24 can be rotated at a second speed V2, which is slower than the first speed V1. In this way, the printer 1 rotates the carry motor 24 at the second speed V2 using pseudo-PWM control. The second speed V2 can be changed within a range that does not exceed the first speed V1 by adjusting the duty ratio of the ON signal and OFF signal that the CPU 91 inputs to the electronic governor circuit 81.

[0043] In this embodiment, the cycle in which the CPU 91 switches between outputting an ON signal and outputting an OFF signal is approximately 1 millisecond. This cycle is shorter than the time dT (approximately 100 milliseconds) required for the carry motor 24 to reach the first speed V1 from a speed of 0 after an ON signal is input to the electronic governor circuit 81. The cycle is also shorter than the time (approximately 100 milliseconds) required for the carry motor 24 to reach the first speed V1 from a speed of 0 after an OFF signal is input to the electronic governor circuit 81. The carry motor 24 alternates between supplying and stopping current from the electronic governor circuit 81, but because the carry motor 24 rotates due to inertia, the speed of the carry motor 24 does not change significantly from the second speed V2. In this embodiment, the duty ratio is 30%. Hereinafter, the process in which the CPU 91 alternately switches between outputting an ON signal and outputting an OFF signal is referred to as deceleration processing.

[0044] The CPU 91 continues the deceleration process for a predetermined period of time. The predetermined period ΔT is from time T21 to time T22, and the length of the predetermined period ΔT is (T22 - T21). In this embodiment, the predetermined period ΔT is several hundred milliseconds. Since the predetermined period ΔT is sufficiently large compared to the length of the cycle, at time T22, at the end of the predetermined period ΔT, the rotational speed of the carry motor 24 is stabilized at the second speed V2. Note that the predetermined period ΔT differs depending on the type of medium 50. The relationship between the predetermined period ΔT and the type of medium 50 will be described later.

[0045] Referring to Figure 8, the control of the transport of the medium 50 in the printer 1 and printing on the medium 50 will be described. The printer 1 prints on the medium 50 while transporting the medium 50. At time 0, the CPU 91 outputs an ON signal for the motor signal to the electronic governor circuit 81, starting transport of the medium 50. The transport motor 24 rotates at a first speed V1, and the encoder 240 outputs a pulse signal corresponding to the rotation of the transport motor 24 to the CPU 91. Note that because the encoder 240 outputs pulse signals at very short intervals, for ease of explanation, Figures 7 and 8 do not show the waveforms of each pulse signal; instead, periods during which the encoder 240 outputs a pulse signal are shown as ON, and periods during which the encoder 240 does not output a pulse signal are shown as OFF.

[0046] The CPU 91 outputs a strobe signal in synchronization with the interval at which the pulse signal is input from the encoder 240, causing the heating element 110 to generate heat. This causes one line of an image corresponding to the print data to be printed on the medium 50. Note that the CPU 91 outputs serial data indicating the print data and a latch signal in synchronization with the strobe signal, so the serial data output and latch signal output are also synchronized with the interval at which the pulse signal is input from the encoder 240.

[0047] The CPU 91 begins deceleration processing at time T21, alternately switching between outputting an ON signal and outputting an OFF signal to the electronic governor circuit 81. The carry motor 24 decelerates from the first speed V1 to the second speed V2. As in the period from time 0 to time T21, the encoder 240 outputs a pulse signal to the CPU 91 in accordance with the rotation of the carry motor 24. The CPU 91 outputs a strobe signal in synchronization with the interval at which the pulse signal is input from the encoder 240, causing the heating element 110 to generate heat. As the rotation speed of the carry motor 24 decelerates, the interval at which the encoder 240 inputs a pulse signal to the CPU 91 becomes longer, and the interval at which the CPU 91 outputs a strobe signal also becomes longer. Because the CPU 91 outputs the strobe signal in synchronization with the interval at which the pulse signal is input from the encoder 240, the interval between printed lines does not change even when the carry motor 24 changes from the first speed V1 to the second speed V2.

[0048] The CPU 91 continues the deceleration process for a predetermined period ΔT (T22-T21). The CPU 91 outputs an OFF signal to the electronic governor circuit 81 at time T22. The carry motor 24 continues to rotate due to inertia after time T22 and stops rotating at time T23. Since the carry motor 24 rotates until time T23, the encoder 240 outputs a pulse signal until time T23.

[0049] After the carry motor 24 stops at time T23, the medium 50 moves a post-stop movement amount dL2 due to the strain energy accumulated in the platen roller 14. Because the carry motor 24 stops after a predetermined period of deceleration processing, the post-stop movement amount dL2 is smaller than the post-stop movement amount dL1 (see FIG. 7) when no deceleration processing is performed. The variation in the post-stop movement amount dL2 is smaller than the variation in the post-stop movement amount dL1 (see FIG. 7) when no deceleration processing is performed.

[0050] Because the CPU 91 prints in synchronization with the interval at which the pulse signal is input from the encoder 240, printing synchronized with the pulse signal stops after the carry motor 24 stops at time T23. Here, since the medium 50 continues to move by the post-stop movement amount dL2 even after the carry motor 24 stops, there is a possibility that a gap where printing is interrupted, i.e., a white line, may occur between the last line printed when printing stops and the first line printed when printing resumes.

[0051] After the carry motor 24 stops, the printer 1 stops printing synchronized with the pulse signal and starts timer control processing. More specifically, when the rotation of the carry motor 24 stops, the CPU 91 no longer receives pulse signals from the encoder 240. After a pulse signal is input from the encoder 240 at time T23, the CPU 91 starts clocking when a period TB has elapsed during which no pulse signals are input from the encoder 240. In the timer control processing, the CPU 91 outputs a strobe signal when a predetermined period has elapsed since starting clocking, thereby causing the heating element 110 to heat and perform printing. This printing performed according to the timed time is referred to as timer control processing. In this embodiment, printing is performed when time TB has elapsed since time T23, when time (TB+TC1) has elapsed since time T23, and when time (TB+TC1+TC2) has elapsed since time T23. In other words, the predetermined periods for the timer control processing are TC1 and TC2. Printing synchronized with the intervals at which pulse signals are input from the encoder 240 from time 0 to time T23 is called synchronous control processing.

[0052] The timer control process continues from time T23+TB to time T24. The period during which the timer control process continues is referred to as period TS. The timer control process suppresses the occurrence of white lines even when printing is stopped and restarted.

[0053] 9, the table 99 stored in the storage unit 94 will be described. The table 99 stores the relationship between type information indicating the type of medium 50, the predetermined period ΔT, and the amount of movement after stopping dL. Here, the predetermined period ΔT and the amount of movement after stopping dL are the magnitudes when the transport control of the medium 50 shown in FIG. 8 is performed. The detection unit 19 outputs the type information to the CPU 91 based on the indicator portion 31 of the tape cassette 30. The CPU 91 detects the type of medium 50 from the type information and determines the predetermined period ΔT and the amount of movement after stopping dL based on the table 99.

[0054] The transport distance L2 of the medium 50 is the sum of the lengths L21, L22, L23, and the post-stop movement distance dL2. The post-stop movement distance dL2 is determined based on table 99. The length L23 is the length the medium 50 is transported while the transport motor 24 is moving from the second speed V2 to a stop, and is determined from the second speed V2 and times T22 and T23. The length L22 is the length the medium 50 is transported during the deceleration process, and is determined from the second speed V2 and a predetermined period ΔT. The predetermined period ΔT is determined based on table 99. Since the predetermined period ΔT is (T22 - T21), time T21 is determined from time T22 and the predetermined period ΔT. The length L21 is determined from the first speed V1 and time T1. Therefore, once the transport distance L2 of the medium 50 is set, the lengths L21, L22, L23, and post-stop movement distance dL2 are each determined from the type information. This allows the CPU 91 to transport the medium 50 by the set transport distance L2.

[0055] The main processing executed by the CPU 91 will be described with reference to Figure 10. In the main processing, the medium 50 is transported and printing is performed on the medium 50. When power is supplied to the printer 1 from the power supply 20, the CPU 91 reads the main processing program from the ROM 92. This causes the CPU 91 to start the main processing.

[0056] When the main processing starts, the CPU 91 determines whether or not a tape cassette 30 is loaded in the loading portion 8 (S1). In S1, the CPU 91 makes this determination based on whether or not type information has been input from the detection unit 19. When the CPU 91 determines that type information has not been input and that a tape cassette 30 is not loaded in the loading portion 8 (S1: NO), the processing returns to S1. When the CPU 91 determines that type information has been input and that a tape cassette 30 is loaded in the loading portion 8 (S1: YES), the CPU 91 determines the predetermined period ΔT and the post-stop movement amount dL based on the input type information and table 99 shown in FIG. 9 (S3).

[0057] The CPU 91 determines whether an instruction to start printing on the medium 50 has been input (S4). When starting printing on the medium 50, the user operates the operation unit 2 to input the start instruction. The start instruction includes print data, the transport amount L2, etc. When the CPU 91 determines that a start instruction has not been input (S4: NO), the process returns to S1. When the CPU 91 determines that a start instruction has been input (S4: YES), the CPU 91 determines lengths L21, L22, and L23 based on the transport amount L2 included in the start instruction, the length ΔT of the fixed period determined in S3, and the post-stop movement amount dL (S5).

[0058] The CPU 91 outputs an ON signal to the electronic governor circuit 81, driving the platen roller 14 to start transporting the medium 50 (S6). The transport motor 24 rotates at a first speed V1. As the medium 50 is transported, strain energy accumulates in the platen roller 14. The encoder 240 outputs a pulse signal to the CPU 91 in accordance with the rotation of the transport motor 24. The CPU 91 starts synchronization control processing (S7). In the synchronization control processing, the CPU 91 outputs a strobe signal in synchronization with the interval at which the pulse signal is input. The printer 1 repeatedly prints one line while transporting the medium 50.

[0059] The CPU 91 determines whether to stop printing on the medium 50 (S11). In S11, the CPU 91 determines to stop printing on the medium 50 when time T21 has elapsed since conveyance began in S6, or when an instruction to stop printing is input. When the user wants to stop printing on the medium 50, the user operates the operation unit 2 to input a stop instruction. When the CPU 91 determines not to stop printing on the medium 50 (S11: NO), the process returns to S11.

[0060] When the CPU 91 determines that printing on the medium 50 should be stopped (S11: YES), it starts deceleration processing (S12). In the deceleration processing, the CPU 91 alternately switches between outputting an ON signal and outputting an OFF signal to the electronic governor circuit 81. The carry motor 24 decelerates from the first speed V1 to the second speed V2. Through synchronization control processing, the CPU 91 outputs a strobe signal in synchronization with the interval at which the pulse signal is input.

[0061] The CPU 91 starts timing based on the clock signal (S13). The CPU 91 determines whether a predetermined period ΔT has elapsed since starting timing in S13 (S14). If the CPU 91 determines that the predetermined period ΔT has not elapsed (S14: NO), the process returns to S14. If the CPU 91 determines that the predetermined period ΔT has elapsed (S14: YES), the CPU 91 ends the deceleration process (S15) and executes the stop process (S16). In the stop process, the CPU 91 outputs an OFF signal to the electronic governor circuit 81. The carry motor 24 stops at time T23. After the carry motor 24 stops, the medium 50 moves a post-stop movement amount dL due to the strain energy accumulated in the platen roller 14.

[0062] The CPU 91 starts timing based on the clock signal (S21). The CPU 91 determines whether or not a pulse signal has been input from the encoder 240 (S22). When the CPU 91 determines that a pulse signal has been input from the encoder 240 (S22: YES), it determines that the rotation of the carry motor 24 has not stopped, and returns the process to S21. When the CPU 91 determines that a pulse signal has not been input from the encoder 240 (S22: NO), it determines whether or not a period TB has elapsed since the start of timing in S21 (S23). When the CPU 91 determines that the period TB has not elapsed (S23: NO), it returns the process to S22.

[0063] When the CPU 91 determines that the period TB has elapsed (S23: YES), it ends the synchronization control process started in S7 and starts the timer control process (S25). In the timer control process, a strobe signal is output when the timer control process is started and when the predetermined cycles TC1 and TC2 of the timer control process have elapsed, and printing is performed on the medium 50.

[0064] The CPU 91 determines whether the period TS has elapsed since the start of the timer control process (S26). When the CPU 91 determines that the period TS has not elapsed (S26: NO), the process returns to S26. When the CPU 91 determines that the period TS has elapsed (S26: YES), the CPU 91 ends the timer control process started in S25.

[0065] The CPU 91 determines whether an instruction to resume printing on the medium 50 has been input (S31). When the user wants to resume printing on the stopped medium 50, the user operates the operation unit 2 to input the resume instruction. When the CPU 91 determines that a resume instruction has been input (S31: YES), the process returns to S6. The CPU 91 outputs an ON signal to the electronic governor circuit 81, and resumes transport of the medium 50 (S6).

[0066] When the CPU 91 determines that a resume instruction has not been input (S31: NO), it determines whether an instruction to end printing on the medium 50 has been input (S32). When the user wants to end printing on the medium 50, the user operates the operation unit 2 to input an end instruction. When the CPU 91 determines that an end instruction has not been input (S32: NO), it returns the process to S31.

[0067] When the CPU 91 determines that an end command has been input (S32: YES), it rotates the output shaft of the cutting motor 23 and causes the cutter unit 11 to cut the medium 50 (S33). This creates a label with an image printed on the medium 50. The CPU 91 returns the process to S1.

[0068] As described above, the printer 1 includes the thermal head 10, the carry motor 24, the platen roller 14, the electronic governor circuit 81, and the CPU 91. The thermal head 10 has multiple heating elements 110 and prints on the medium 50. The carry motor 24 is a DC motor. The platen roller 14 is driven by the rotation of the carry motor 24 and transports the medium 50 sandwiched between it and the thermal head 10. The electronic governor circuit 81 supplies current to the carry motor 24 while an ON signal is input, and stops supplying power to the carry motor 24 while an OFF signal is input. The CPU 91 outputs an ON or OFF signal to the electronic governor circuit 81 to control the driving of the electronic governor circuit 81. In the main processing, when transporting the medium 50, the CPU 91 outputs an ON signal to the electronic governor circuit 81 to rotate the carry motor 24 at a first speed V1 (S6). When stopping the transport of the medium 50, the CPU 91 executes a deceleration process (S12) that alternates between outputting an ON signal and outputting an OFF signal so that the transport motor 24 rotates at the second speed V2. After continuing the deceleration process for a predetermined period ΔT, the CPU 91 executes a stop process (S16) that outputs an OFF signal to the electronic governor circuit 81.

[0069] According to this, while printing on the medium 50 is being performed, the printer 1 outputs an ON signal to the electronic governor circuit 81 to rotate the carry motor 24 at a first speed V1. When stopping printing on the medium 50, the printer 1 executes a deceleration process. During the deceleration process, the CPU 91 alternately outputs an ON signal and an OFF signal to the electronic governor circuit 81 so that the carry motor 24 rotates at a second speed V2. In this way, the printer 1 performs pseudo-PWM control, and the carry motor 24 rotates at a second speed V2 that is slower than the first speed V1. After continuing the deceleration process for a predetermined period ΔT, the printer 1 outputs an OFF signal to the electronic governor circuit 81 to stop the transport of the medium 50. This reduces the strain energy accumulated in the platen roller 14. Therefore, compared to when the printer 1 stops the medium 50 from the first speed V1, the printer 1 reduces the post-stop movement amount dL, thereby suppressing variation in the post-stop movement amount dL.

[0070] The printer 1 has an encoder 240 that outputs pulse signals corresponding to the rotation of the carry motor 24. During the main processing, the CPU 91 executes synchronization control processing (S7) to output a strobe signal in synchronization with the interval at which the pulse signal is input from the encoder 240, thereby causing the heating elements 110 to generate heat. This allows the printer 1 to print on the medium 50 by causing the multiple heating elements 110 to generate heat. Because the encoder 240 outputs pulse signals to the CPU 91 in accordance with the rotation of the carry motor 24, the interval at which the CPU 91 receives the pulse signal from the encoder 240 indicates the rotation speed of the carry motor 24. The CPU 91 causes the heating elements 110 to generate heat in synchronization with the interval at which the pulse signal is input. This synchronizes the timing at which the heating elements 110 generate heat with the rotation speed of the carry motor 24. Therefore, the printer 1 can ensure the quality of the image printed on the medium 50, even when the rotation speed of the carry motor 24 changes from the first speed V1 to the second speed V2.

[0071] In the printer 1, when the CPU 91 stops the carry motor 24 through the stop process (S16), it stops the heat generation of the heating element 110 through the synchronization control process (S24), and then causes the heating element 110 to generate heat at predetermined cycles TC1 and TC2 through the timer control process. In this way, the medium 50 continues to move due to the strain energy accumulated in the platen roller 14 even after the carry motor 24 has stopped, but because the printer 1 executes the timer control process after the rotation of the carry motor 24 has stopped, the occurrence of white lines is suppressed. Therefore, the printer 1 can ensure the quality of the image printed on the medium 50.

[0072] The printer 1 has a detection unit 19 and a memory unit 94. The detection unit 19 receives type information based on the ON / OFF combination of the detection switch. The memory unit 94 stores the predetermined period ΔT corresponding to the type information of the medium 50 using a table 99. According to this, the post-stop movement amount dL differs depending on the type of medium 50. In the printer 1, the memory unit 94 stores the predetermined period ΔT corresponding to the type information of the medium 50 using the table 99. Therefore, the printer 1 can transport the medium 50 by the predetermined transport amount L2 even when the type of medium 50 is different.

[0073] The printer 1 has an electronic governor circuit 81. While an ON signal is being input, the electronic governor circuit 81 controls the voltage supplied to the carry motor 24 so that the carry motor 24 rotates at the first speed V1. While an OFF signal is being input, the electronic governor circuit 81 stops the supply of power to the carry motor 24. In this way, the CPU 91 outputs a motor signal to the electronic governor circuit 81. While an ON signal is being input, the electronic governor circuit 81 controls the voltage supplied to the carry motor 24 so that the carry motor 24 rotates at the first speed V1. Therefore, compared to when the printer 1 further has a non-stable voltage supply circuit that turns the supply of power to the carry motor 24 on and off, the printer 1 can suppress variation in the post-stop movement amount dL and the post-stop movement amount dL with a simpler configuration.

[0074] The present invention can be modified in various ways from the above-described embodiment. The various modifications described below can be combined with each other as long as no contradiction occurs.

[0075] The printer 1 may use, for example, a microcomputer, an ASIC (Application Specific Integrated Circuits), an FPGA (Field Programmable Gate Array), etc. for control instead of the CPU 91. The main processing may be distributed using multiple CPUs 91, or may be performed by combining the CPU 91 with an ASIC, etc.

[0076] Non-transitory storage media such as the ROM 92 and the storage unit 94 may be any storage media capable of retaining information regardless of the period for which the information is stored. A non-transitory storage medium does not have to include a temporary storage medium (e.g., a transmitted signal). The program for executing the main processing, the table 99, etc. may be downloaded (i.e., transmitted as a transmission signal) from a server connected to the network and stored in the storage unit 94, etc. In this case, the program, etc. may be stored in a non-transitory storage medium such as an HDD provided in the server.

[0077] The conveying motor 24 may be a DC motor, such as a brushless DC motor or a stepping motor.

[0078] The magnitude of the first speed V1 may be changed as appropriate. The magnitude of the second speed V2 may be changed as appropriate within a range greater than speed 0 and less than the first speed V1. In the deceleration process, the length of the cycle in which the output of the ON signal and the output of the OFF signal are switched may be changed as appropriate. The duty ratio between the output of the ON signal and the output of the OFF signal may be changed as appropriate. The length of the predetermined period ΔT may be changed as appropriate as long as it is greater than the length of the cycle in which the output of the ON signal and the output of the OFF signal are switched.

[0079] In the deceleration process, the CPU 91 may decelerate the carry motor 24 from the first speed V1 to the second speed V2, and then decelerate the carry motor 24 from the second speed V2 to a third speed that is slower than the second speed V2.

[0080] The printer 1 does not need to have the encoder 240. The CPU 91 does not need to execute synchronization control processing. In other words, the CPU 91 does not need to synchronize the interval at which the pulse signal is input from the encoder 240 with the output of the strobe signal. In the main processing, the CPU 91 may perform printing on the medium 50 using only the timer control processing.

[0081] The CPU 91 does not have to execute the timer control process. In this case, in the main process, the CPU 91 may perform printing on the medium 50 only through the synchronous control process.

[0082] In the above embodiment, the detection unit 19 received the type information indicated by the indicator portion 31 of the tape cassette 30. Alternatively, the operation unit 2 may receive the type information. In this case, the user operates the operation unit 2 to input the type information of the medium 50. The configuration of the detection unit 19 may be changed as appropriate. For example, the detection unit 19 may receive the type information using multiple reflective sensors. The memory unit 94 does not need to store the predetermined period ΔT corresponding to the type information, and does not need to store the table 99. The table 99 does not need to store the post-stop movement amount dL corresponding to the type information.

[0083] The configuration of the printer 1 may be changed as appropriate. The printer 1 may not have the cutter unit 11. The configuration of the cutter unit 11 may be changed as appropriate. In the above embodiment, the cutter unit 11 cuts the medium 50 with the movable blade 12 and the receiving base 13, but the medium 50 may also be cut with a movable blade and a fixed blade. The printer 1 may not have the display 5. The printer 1 may not have the operation unit 2.

[0084] The medium 50 does not have to be housed in the case 39 of the tape cassette 30. In this case, the medium 50 may be thermal roll paper wound around a core material. The configuration of the tape cassette 30 may be changed as appropriate. In this case, the tape cassette 30 may be a receptor type that further includes an ink ribbon. The ink ribbon transfers ink to the medium 50 by heat generated by the heating element 110. The table 99 of the memory unit 94 may further store information on the type of ink ribbon. The tape cassette 30 may be a laminate type that further includes an ink ribbon and double-sided adhesive tape. The table 99 of the memory unit 94 may further store information on the type of double-sided adhesive tape. The medium 50 does not have to be thermal tape.

[0085] The conveying motor 24 is an example of a "DC motor" of the present invention. The electronic governor circuit 81 is an example of a "motor drive unit" or "electronic governor circuit" of the present invention. The CPU 91 is an example of a "control unit" of the present invention. The processing of S6 is an example of a "constant speed processing," "constant speed process," or "constant speed step" of the present invention. The processing of S12 is an example of a "deceleration processing," "deceleration process," or "deceleration step" of the present invention. The processing of S16 is an example of a "stop processing," "stop process," or "stop step" of the present invention. The processing of S7 is an example of a "synchronization control processing" of the present invention. The processing of S25 is an example of a "timer control processing" of the present invention. The detection unit 19 is an example of a "reception unit" of the present invention. [Explanation of symbols]

[0086] 1. Printer 10 Thermal head 14 Platen roller 19 Detector 24 Transport motor 81 Electronic Governor Circuit 91 CPU 94 Memory section 110 Heating element 240 encoder

Claims

1. a thermal head having a plurality of heating elements for printing on a medium; a DC motor; a platen roller that is driven by the rotation of the DC motor and that conveys the medium while sandwiching it between itself and the thermal head; a motor driving unit that supplies current to the DC motor while an ON signal is being input, and stops supplying the current to the DC motor while an OFF signal is being input; a control unit that outputs the ON signal or the OFF signal to the motor drive unit and controls the motor drive unit, The control unit a constant speed process for outputting the ON signal to the motor drive unit to rotate the DC motor at a first speed when the medium is being transported; When the transport of the medium is stopped, a deceleration process of alternately switching between outputting the ON signal and outputting the OFF signal so that the DC motor rotates at a second speed that is lower than the first speed; a stop process of outputting the OFF signal after continuing the deceleration process for a predetermined period of time; A printer characterized by performing the above.

2. The DC motor further includes an encoder that outputs a pulse signal corresponding to the rotation of the DC motor to the control unit. The control unit Further, a synchronous control process is executed to make the heating element generate heat in synchronization with the interval at which the pulse signal is input from the encoder.

2. The printer according to claim 1, wherein:

3. The control unit After the heat generation by the heat generating element is stopped by the synchronous control process in response to the DC motor being stopped by the stop process, a timer control process is further executed to cause the heat generating element to generate heat at a predetermined cycle.

3. The printer according to claim 2, wherein:

4. a receiving unit that receives the medium type information; a storage unit that stores the predetermined period corresponding to the type information.

2. The printer according to claim 1, wherein:

5. The motor drive unit is an electronic governor circuit that controls a voltage supplied to the DC motor so that the DC motor rotates at the first speed while the ON signal is being input, and stops the supply of the current to the DC motor while the OFF signal is being input.

2. The printer according to claim 1, wherein:

6. A method for controlling a printer including: a thermal head having a plurality of heat generating elements for printing on a medium; a DC motor; a platen roller driven by rotation of the DC motor and sandwiching and transporting the medium between the thermal head and the platen roller; a motor drive unit that supplies current to the DC motor while an ON signal is input and stops supplying the current to the DC motor while an OFF signal is input; and a control unit that outputs the ON signal or the OFF signal to the motor drive unit and controls the motor drive unit, a constant speed step of outputting the ON signal to the motor drive unit to rotate the DC motor at a first speed when the medium is being transported; When the transport of the medium is stopped, a deceleration step of alternately switching between outputting the ON signal and outputting the OFF signal so that the DC motor rotates at a second speed that is lower than the first speed; a stopping step of outputting the OFF signal after continuing the deceleration step for a predetermined period of time; A control method comprising:

7. A program to be executed by a computer that controls a printer including: a thermal head having a plurality of heat generating elements and that prints on a medium; a DC motor; a platen roller that is driven by the rotation of the DC motor and that sandwiches and transports the medium between the thermal head and the platen roller; a motor drive unit that supplies current to the DC motor while an ON signal is input and stops the supply of current to the DC motor while an OFF signal is input; and a control unit that outputs the ON signal or the OFF signal to the motor drive unit and controls the motor drive unit, a constant speed step in which, when conveying the medium, the ON signal is output to the motor drive unit to rotate the DC motor at a first speed; When the transport of the medium is stopped, a deceleration step of alternately switching between outputting the ON signal and outputting the OFF signal so that the DC motor rotates at a second speed that is lower than the first speed; a stop step of outputting the OFF signal after continuing the deceleration step for a predetermined period of time; A program that causes the computer to execute the above.

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