printer

Abstract

To provide a printer that, even when a battery voltage fluctuates, is able to appropriately operate the function of preventing damage to a gear connected to a DC motor.SOLUTION: A printer includes a head, a platen roller, a drive gear, a DC motor, and a CPU. The head executes printing on a medium by electric power of the battery. The platen roller conveys the medium. The drive gear drives the platen roller. The DC motor is rotated by electric power of the battery and drives the drive gear. The CPU detects, N times (N is a positive number of 1 or more), a detection signal S corresponding to a rotation speed of the DC motor (S9). The CPU calculates an N-th variation parameter, based on the detected N-th detection signal S (S23). The CPU determines a relation between the calculated N-th variation parameter and the detected (N + 1)-th detection signal S (S15).SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a printer. [Background technology]

[0002] Patent Document 1 discloses a motor control device that prevents damage to gears connected to a DC motor. The motor control device includes a detection unit, a determination unit, and a motor control unit. The detection unit detects the rotation speed of the DC motor. The determination unit determines whether the detected rotation speed is below a lower limit rotation speed. If the detected rotation speed is below the lower limit rotation speed, the motor control unit stops the DC motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-30311 Summary of the Invention [Problem to be solved by the invention]

[0004] In the motor control device described above, fluctuations in battery voltage, for example, can cause variations in the rotation speed of the DC motor. For example, a drop in battery voltage can cause the rotation speed of the DC motor to fall below the minimum rotation speed limit. In this case, the DC motor control device stops the DC motor even if there is little risk of damage to the gears.

[0005] An object of the present invention is to provide a printer that can properly operate a function for preventing damage to gears connected to a DC motor even when the battery voltage fluctuates. [Means for solving the problem]

[0006] The printer of the present invention is a battery-powered printer comprising: a head that prints on a medium using power from the battery; a platen roller that transports the medium; a drive gear that drives the platen roller; a DC motor that rotates using power from the battery and drives the drive gear; and a control unit, wherein the control unit executes a detection process that detects a detection signal corresponding to the rotational speed of the DC motor N times (N is a positive number greater than or equal to 2); a calculation process that calculates an N-1th variable parameter based on the N-1th detection signal detected by the detection process; and a determination process that determines the relationship between the N-1th variable parameter calculated by the calculation process and the Nth detection signal detected by the detection process.

[0007] The printer does not judge the relationship between the detection signal and a fixed value, but rather judges the relationship between the Nth detection signal and the N-1th variable parameter calculated based on the N-1th detection signal. Therefore, the printer is less susceptible to fluctuations in the rotation speed of the DC motor due to fluctuations in battery voltage, for example. Therefore, the printer can properly operate the function that prevents damage to the gears connected to the DC motor even when the battery voltage fluctuates.

[0008] In the present invention, the determination process may determine whether the detection signal has exceeded the fluctuation parameter, and the control unit may further execute a stop process to stop driving the DC motor if the determination process determines that the detection signal has exceeded the fluctuation parameter. Because the printer determines the relationship between the detection signal and the fluctuation parameter, the possibility of erroneously stopping the DC motor can be reduced.

[0009] In the present invention, the stop process may stop driving of the DC motor when the determination process determines that the detection signal has exceeded the fluctuation parameter multiple times in succession, enabling the printer to make a determination that is robust against fluctuations in battery voltage, further reducing the possibility of erroneously stopping the DC motor.

[0010] In the present invention, the DC motor may be provided with an encoder, and the detection process may detect an output result of the encoder as the detection signal. The printer can detect the detection signal without providing a separate sensor.

[0011] In the present invention, the control unit may execute a correction process to correct the printing operation at a predetermined cycle, and the determination process may determine the relationship between the detection signal and the variable parameter in synchronization with the predetermined cycle in which the printing operation is corrected by the correction process. By synchronizing the determination of the relationship between the detection signal and the variable parameter with the correction of the printing operation, the printer can reduce the load on the control unit.

[0012] In the present invention, the calculation process may calculate the (N-1)th variable parameter by multiplying the (N-1)th detection signal detected by the detection process by a predetermined ratio. The printer can calculate the variable parameter by a simple calculation.

[0013] In the present invention, the calculation process may calculate the (N-1)th variable parameter by adding a predetermined additional value to the (N-1)th detection signal detected by the detection process. The printer can calculate the variable parameter by a simple calculation.

[0014] In the present invention, a sensor may be provided in a transport path of the medium, the medium may have markers arranged at predetermined intervals, and the detection process may detect the detection period of the markers by the sensor as the detection signal. The printer can accurately detect the detection signal using the sensor. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a printer 1. [Figure 2] FIG. 2 is a perspective view of the printer 1 with the rear cover 3 removed. [Figure 3] FIG. [Figure 4]FIG. 2 is a perspective view of the tape cassette 100. [Figure 5] 2 is a block diagram showing the electrical configuration of the printer 1. FIG. [Figure 6] 10 is a diagram showing the characteristics of a DC motor 61. FIG. [Figure 7] 10 is a diagram showing the relationship between a threshold value Th and a detection signal S. FIG. [Figure 8] 10 is a flowchart of a main process. [Figure 9] 10 is a diagram showing the relationship between a fluctuation parameter Pth and a detection signal S. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] A first embodiment of the present invention will be described with reference to the drawings. An overview of the printer 1 will be described with reference to FIGS. 1 and 2. The drawings are used to explain technical features that may be adopted by the present invention. In other words, the configurations and the like shown in the drawings are not intended to be limiting but are merely illustrative examples. In the description of this embodiment, the upper left, lower right, right, left, upper right, and lower left sides of FIG. 1 will be referred to as the lower, upper, right, left, front, and rear sides of the printer 1, respectively.

[0017] The configuration of the printer 1 will now be described. As shown in Figures 1 and 2, the printer 1 is a portable label printer. The printer 1 is powered by a battery housed in a battery housing 40. The printer 1 can create labels with images printed on a tape 101 (see Figure 4) pulled out from a tape cassette 100. Images such as characters and figures are printed on the labels.

[0018] As shown in Figures 1 and 2, the printer 1 comprises a housing 2, a rear cover 3, a display unit 4, and an input unit 5. The housing 2 is box-shaped and long in the front-to-rear direction, with an opening at the rear. An inner lid 6 is attached to the opening to protect the inside of the housing 2. A discharge passage 29 that penetrates in the front-to-rear direction and a fastening hole 2C that engages with an opening / closing portion 31 of the rear cover 3 are formed in the top wall 2A of the housing 2.

[0019] The rear cover 3 is removably attached to the housing 2. The rear cover 3 extends in the front-to-rear direction and has a recessed shape that is recessed upward. When attached, the rear cover 3 covers the entire rear surface of the housing 2 and closes the opening on the rear surface together with the inner lid 6.

[0020] The display unit 4 is provided at a position forward of the center in the front-to-rear direction on the underside 2B of the housing 2. The display unit 4 is, for example, a liquid crystal display, and is capable of displaying various types of information. The input unit 5 is provided on the underside 2B of the housing 2, behind the display unit 4. The input unit 5 includes multiple keys such as character keys, a print button, and an Esc key. The input unit 5 accepts input of various types of information by user operation. The user operates the display unit 4 and the input unit 5 to edit the print data.

[0021] As shown in Figure 2, the printer 1 includes a cassette loading section 10, a battery housing section 40, and a printing section 50 inside the housing 2. A tape cassette 100 is removably mounted in the cassette loading section 10. The cassette loading section 10 is formed in the inner cover 6 on the rear of the housing 2, at a position forward of the center in the front-to-rear direction. The cassette loading section 10 is recessed downward.

[0022] The battery housing section 40 houses a battery. The battery housing section 40 is formed in the inner lid 6 on the back of the housing 2, in a recessed shape that is recessed downward, at a position rearward of the center of the housing 2 in the front-to-rear direction. With the rear cover 3 removed from the housing 2, the user can replace the tape cassette 100 and the battery.

[0023] The printing unit 50 is a unit configured to print on the tape 101. The printing unit 50 is located in the front part of the housing 2, below the left end of the cassette loading unit 10. As shown in FIG. 3, the printing unit 50 includes a head unit 70, a platen unit 80, a drive mechanism 60, etc.

[0024] As shown in FIG. 3, the head unit 70 is assembled to the base 51. The head unit 70 includes a heat sink 72 and a head 71. The heat sink 72 is located at the front end of the base 51, in the center in the left-right direction. The heat sink 72 is a metal plate that holds the head 71 and dissipates heat. The heat sink 72 includes a lower end 72F and a right end 72U. The lower end 72F faces the plate surface in the up-down direction and extends longer in the front-to-rear direction than in the left-to-right direction. The lower end 72F is fixed to the base 51 with a screw. The right end 72U extends upward from the right end of the lower end 72F. The right end 72U faces the plate surface in the left-to-right direction and extends longer in the front-to-rear direction than in the up-to-down direction.

[0025] The head 71 is fixed with adhesive to the left surface of the right end 72U of the heat sink 72. The head 71 is a rectangular circuit board on which multiple heating elements 71A and a drive circuit 71B are mounted. The multiple heating elements 71A are arranged vertically at the front end of the left surface of the board. The drive circuit 71B is formed at the rear end of the left surface of the board and is electrically connected to the CPU 21 (see Figure 5) inside the housing 2 via a harness 73. The head 71 prints on the tape 101 using battery power.

[0026] The platen unit 80 is disposed on the left side of the base 51. The rear end of the platen unit 80 is supported by a rotation shaft 53 so that the front end can swing left and right. The rotation shaft 53 of the platen unit 80 is provided on the left side of the rear end of the base 51 and extends upward. By swinging the platen unit 80, the platen roller 82 can swing between a close position (not shown) where it approaches the head 71 and a distant position (see FIG. 3) where it is away from the head 71.

[0027] The platen unit 80 includes a platen holder 81, a platen shaft 84, a platen roller 82, and a platen gear 83. The platen holder 81 is long in the front-to-rear direction and has a box shape that is open on the right side. The rotation shaft 52 is inserted into the rear end of the platen holder 81. The platen roller 82 is rotatably supported at the front end of the platen holder 81.

[0028] The platen gear 83 is fixed to the upper end of the platen shaft 84. The platen gear 83 is a so-called helical gear, with gear teeth twisted at a predetermined angle relative to the rotation axis. The platen gear 83 meshes with an output gear 131 (see FIG. 4) of the tape cassette 100. The driving force of the drive shaft 63 is input to the platen roller 82 via the output gear 131 and the platen gear 83. The platen roller 82 sandwiches the tape 101 and ink ribbon 104 between itself and the head 71 at the head opening 123 (see FIG. 4). As the platen roller 82 rotates about its axis, it transports the tape 101 toward the discharge path 29.

[0029] The drive mechanism 60 includes a DC motor 61, a gear group 62, and a drive shaft 63, and is assembled to the base 51. The DC motor 61 is driven by battery power. The DC motor 61 is a drive source, and is disposed at the rear end of the base 51. The DC motor 61 is connected to a gear group 62, which connects multiple gears. The gear group 62 is connected to the drive shaft 63. The DC motor 61, the gear group 62, and the base 51 are disposed below the inner lid 6 inside the housing 2.

[0030] The drive shaft 63 is disposed on the right side of the front end of the base 51. The drive shaft 63 is inserted through a rotation shaft 52 provided on the base 51. A driving force transmitted from a DC motor 61 is input to the drive shaft 63 via a gear group 62. This causes the drive shaft 63 to rotate around the rotation shaft 52.

[0031] The tape cassette 100 will be described with reference to Figure 4. By replacing the tape cassette 100, the user can replenish the tape 101 and change the type of tape 101 (for example, size, color, material, etc.). The tape cassette 100 includes a main case 120. The main case 120 is rectangular parallelepiped-shaped. The main case 120 contains the tape 101 and the ink ribbon 104. The tape 101 and the ink ribbon 104 are each wound in a roll inside the main case 120.

[0032] The take-up spool 107 is provided on the front and lower side of the main case 120. The lower end of the take-up spool 107 is exposed downward from the main case 120. The take-up spool 107 is cylindrical and has an inner circumferential surface 108. The rotation axis of the take-up spool 107 is parallel to the rotation axis of the ribbon spool (not shown) around which the ink ribbon 104 is wound. When the tape cassette 100 is mounted in the cassette mounting portion 10, the drive shaft 63 is inserted into the inner circumferential surface 108. The take-up spool 107 is rotated by the drive shaft 63. The ink ribbon 104 is transported from the ribbon spool (not shown) toward the head opening 123. After passing through the head opening 123, the ink ribbon 104 is taken up onto the take-up spool 107.

[0033] The output gear 131 is provided on the upper left side of the take-up spool 107, in the vertical center. The output gear 131 is exposed to the left from the main case 120. The rotation axis of the output gear 131 is the same as the rotation axis of the take-up spool 107. The output gear 131 meshes with the platen gear 83 (see FIG. 3) when the platen roller 82 (see FIG. 3) is in the proximity position (not shown).

[0034] The output gear 131 is connected to a drive transmission mechanism (not shown) arranged inside the main case 120. The drive transmission mechanism (not shown) is connected to the output gear 131 and also to the upper end of the drive shaft 63 inserted into the take-up spool 107. The drive transmission mechanism (not shown) is composed of, for example, a plurality of gears. As the drive shaft 63 rotates, the drive transmission mechanism (not shown) transmits a driving force to the output gear 131. This causes the platen gear 83 to rotate, which in turn causes the platen roller 82 to rotate. The platen roller 82 feeds the tape 101. Therefore, in the tape cassette 100, as the drive shaft 63 rotates, the tape 101 and the ink ribbon 104 are fed.

[0035] The electrical configuration of the printer 1 will be described with reference to Figure 5. The printer 1 further includes a CPU 21, a RAM 22, a flash memory 23, an EEPROM 24, drive circuits 61B and 71B, etc. The CPU 21 controls the printer 1. The CPU 21 is electrically connected to the RAM 22, the flash memory 23, the EEPROM 24, the drive circuits 61B and 71B, the display unit 4, and the input unit 5.

[0036] The RAM 22 temporarily stores various data. The flash memory 23 stores various programs that the CPU 21 executes to control the printer 1. The EEPROM 24 stores printing dot pattern data, categorized by font and size.

[0037] The drive circuit 61B drives the DC motor 61 in accordance with instructions from the CPU 21. The DC motor 61 is provided with an encoder 61A. The encoder 61A outputs pulses that indicate the rotation position of the DC motor 61. The pulses output from the encoder 61A are output to the CPU 21. The drive circuit 71B selectively heats the heating element 71A of the head 71 in accordance with instructions from the CPU 21.

[0038] The display unit 4 displays various information in accordance with instructions from the CPU 21. The input unit 5 transmits to the CPU 21 various instructions input by the user.

[0039] The relationship between the rotation speed Rn and torque T of the DC motor 61 will be described with reference to Figure 6. The rotation speed Rn on the vertical axis represents the rotation speed of the DC motor 61. The torque T on the horizontal axis represents the force required to rotate the shaft of the DC motor 61. For example, line L1 represents the characteristics when the battery is in good condition and the battery voltage is high. Line L2 represents the characteristics when the battery is in normal condition and the battery voltage is medium. Line L3 represents the characteristics when the battery is in a deteriorated state and the battery voltage is low.

[0040] The higher the torque T, the lower the rotation speed Rn of the DC motor 61. The lower the torque T, the higher the rotation speed Rn of the DC motor 61. Furthermore, the rotation speed Rn of the DC motor 61 changes depending on the battery voltage of the battery. For example, in terms of torque Tn, the rotation speed Rn of the DC motor 61 decreases as the battery voltage decreases (see intersections P1, P2, and P3).

[0041] 6 and 7, stopping the DC motor 61 to prevent damage to the gears will be described. For example, suppose a malfunction occurs for some reason in the gear group 62 that transmits driving force to the platen roller 82, the drive transmission mechanism (not shown), the output gear 131, the platen gear 83 (hereinafter collectively referred to as the "drive gear"), or the like. For example, in the case of line L1, the rotation speed Rn of the DC motor 61 decreases (see arrow A1). In this case, the torque T of the DC motor 61 increases from torque Tn (see arrow A2). If the rotation speed Rn of the DC motor 61 continues to decrease, the torque T of the DC motor 61 reaches a threshold torque Tp. In this case, the drive gear connected to the DC motor 61 is damaged. Note that, if the battery deteriorates from a new state (line L2, line L3), the torque T similarly increases as the rotation speed Rn decreases. Therefore, it is necessary to stop the DC motor 61 before the torque T of the DC motor 61 reaches the threshold torque Tp.

[0042] As shown in FIG. 7, the printer 1 compares the detection signal S of the encoder 61A of the DC motor 61 with a threshold value Th to determine whether to stop driving the DC motor 61 to prevent damage to the drive gear. The printer 1 stops the DC motor 61 when the detection signal S of the encoder 61A exceeds the threshold value Th. Here, the detection signal S of the encoder 61A represents the time it takes to detect the output of the encoder 61A for, for example, 18 pulses. In other words, the detection signal S is a signal that corresponds to the rotation speed Rn of the DC motor 61. When the rotation speed Rn of the DC motor 61 decreases, the detection signal S of the encoder 61A increases. Furthermore, when the rotation speed Rn of the DC motor 61 decreases, the torque T of the DC motor 61 increases. Therefore, an increase in the detection signal S of the encoder 61A indicates an increase in the torque T of the DC motor 61.

[0043] The threshold value Th is a fixed value. For example, the threshold value Th is a value based on the threshold torque Tp at which the gear breaks. For example, if a malfunction occurs in the driving of the drive gear, the detection signal S of the encoder 61A exceeds the threshold value Th at time t2. In this case, the driving of the DC motor 61 is stopped.

[0044] On the other hand, it is assumed that the battery will deteriorate with continued use, causing a drop in battery voltage (for example, line L3 in FIG. 6). In this case, the rotation speed Rn of the DC motor 61 will decrease, and the torque T of the DC motor 61 will increase (see FIG. 6). That is, the detection signal S will increase not only due to a malfunction of the drive gear, but also due to battery deterioration. Due to a drop in battery voltage, the detection signal S exceeds the threshold value Th at time t1. This causes the drive of the DC motor 61 to stop. That is, the drive of the DC motor 61 will stop even if there is no malfunction in the drive gear.

[0045] To deal with such a case, it is necessary to set a threshold higher than the threshold Th shown in Fig. 7. On the other hand, if the threshold Th is set too high, it may not be possible to detect a malfunction in the drive gear. Therefore, in order to properly stop the DC motor 61 to prevent damage to the gear, it may be problematic to have the threshold Th set to a fixed value.

[0046] The main processing will be described with reference to Fig. 8. For example, the user edits print data and presses the print execution button. In this case, the CPU 21 reads and executes a program from the flash memory 23. Once the program is executed, the CPU 21 starts the main processing.

[0047] When the main processing starts, the CPU 21 sets i to 0 (S1). The CPU 21 sets N to 1 (S3). The CPU 21 starts feeding the tape 101 (S5). The CPU 21 determines whether the tape 101 has been fed by the desired amount (S7). Here, the desired amount is the amount of feeding of the tape 101 at the time when printing is completed. The desired amount can be specified based on the print data. The feed amount is specified based on the number of pulses of the encoder 61A of the DC motor 61.

[0048] If it is determined that the tape 101 has not been fed by the desired amount (S7: NO), the CPU 21 determines whether or not the Nth detection signal S has been acquired (S9). If it is determined that the detection signal S has not been acquired (S9: NO), that is, if an output of 18 pulses has not been detected, the CPU 21 returns the process to S7.

[0049] If it is determined that the Nth detection signal S has been acquired (S9: YES), the CPU 21 performs print cycle correction to correct the printing operation (S11). Print cycle correction is a process that reduces the enlargement or reduction of an image by correcting the transport speed of the tape 101. The CPU 21 performs print cycle correction at a predetermined cycle. The predetermined cycle is the timing at which 18 pulses of signal are acquired from the encoder 61A.

[0050] The CPU 21 determines whether N is set to 1 (S13). If it is determined that N is set to 1 (S13: YES), the CPU 21 calculates the Nth fluctuation parameter Pth based on the Nth detection signal S acquired in S9 (S23). In this case, since N is 1, the first fluctuation parameter Pth is calculated based on the first detection signal S.

[0051] The fluctuation parameter Pth is a threshold value that fluctuates for every 18 pulses output from the encoder 61A. For example, the CPU 21 calculates the Nth fluctuation parameter Pth by multiplying the Nth detected detection signal S by a predetermined ratio. The predetermined ratio is set in advance. For example, the predetermined ratio is 1.5.

[0052] The CPU 21 increments N by 1 (S25). For example, N is set from 1 to 2. The CPU 21 returns the process to S7. Thereafter, the CPU 21 detects the second detection signal S (S9: YES), and the CPU 21 executes printing cycle correction (S11).

[0053] If it is determined that N is not 1, i.e., that N is set to a value of 2 or greater (S13: NO), the CPU 21 determines whether the Nth detection signal S exceeds the (N-1)th fluctuation parameter Pth (S15). That is, the CPU 21 determines the relationship between the calculated (N-1)th fluctuation parameter Pth and the detected Nth detection signal S. Note that the process of S15 is always performed after the process of S11. That is, the process of S15 is synchronized with the predetermined cycle of printing cycle correction.

[0054] If it is determined that the Nth detection signal S does not exceed the (N-1)th fluctuation parameter Pth (S15: NO), the CPU 21 determines that there is no problem with the detection signal S and initializes i to 0 (S19). The CPU 21 proceeds to S23 and calculates the Nth fluctuation parameter Pth based on the Nth detection signal S (S23).

[0055] If it is determined that the Nth detection signal S has exceeded the (N-1)th fluctuation parameter Pth (S15: YES), the CPU 21 increments i by 1 (S17). The CPU 21 determines whether i is set to 5 (S21). If it is determined that i is not set to 5 (S21: NO), the CPU 21 proceeds to S23 and calculates the Nth fluctuation parameter Pth based on the Nth detection signal S (S23).

[0056] On the other hand, if it is determined that i is set to 5 (S21: YES), the CPU 21 stops driving the DC motor 61 (S27) because there is a risk of damage to the drive gear. This stops the transport of the tape 101. Note that if the determination of S15: YES is repeated in the processing of S15, i continues to be incremented. On the other hand, if the determination of S15: NO is made during the increment of i, i is initialized to 0. Therefore, if i is set to 5, five consecutive determinations of S15: YES are required. In other words, if the CPU 21 determines that the detection signal S has exceeded the fluctuation parameter Pth multiple times (five times) in a row, it stops driving the DC motor 61. The CPU 21 ends the main processing.

[0057] On the other hand, if it is determined that the tape 101 has been fed by the desired amount (S7: YES), printing has been completed, and the CPU 21 ends the main processing.

[0058] Execution of the main processing enables detection such as that shown in FIG. 9. For example, if the detection signal S(N) exceeds the fluctuation parameter Pth(N-1) due to a malfunction of the drive gear, the drive of the DC motor 61 is stopped. This makes it possible to prevent damage to the drive gear. Meanwhile, since the fluctuation parameter Pth'(N-1) is calculated from the detection signal S'(N-1), a comparison is made with the fluctuation parameter Pth'(N-1) that takes into account a drop in battery voltage. Therefore, unlike the example shown in FIG. 7, the possibility of the DC motor 61 being stopped due to a drop in battery voltage is reduced.

[0059] As described above, the CPU 21 calculates the (N-1)th fluctuation parameter Pth based on the detected (N-1)th detection signal S. The CPU 21 determines the relationship between the calculated (N-1)th fluctuation parameter Pth and the detected Nth detection signal S.

[0060] The printer 1 does not determine the relationship between the detection signal S and a fixed value, but determines the relationship between the Nth detection signal S based on the (N-1)th variable parameter Pth calculated based on the (N-1)th detection signal S. Therefore, the printer 1 is less susceptible to fluctuations in the rotation speed of the DC motor 61 due to fluctuations in battery voltage, for example. Therefore, the printer 1 can properly operate the function of suppressing damage to the gear connected to the DC motor 61 even when the battery voltage fluctuates.

[0061] The CPU 21 determines whether the detection signal S has exceeded the fluctuation parameter Pth. If the CPU 21 determines that the detection signal S has exceeded the fluctuation parameter Pth, it stops driving the DC motor 61. Because the printer 1 determines the relationship of the detection signal S with the fluctuation parameter Pth, it is possible to reduce the possibility of erroneously stopping the DC motor 61.

[0062] When the CPU 21 determines that the detection signal S has exceeded the fluctuation parameter Pth multiple times in succession, it stops driving the DC motor 61. The printer 1 can now make a determination that is robust against fluctuations in the battery voltage, further reducing the possibility of erroneously stopping the DC motor 61.

[0063] An encoder 61A is provided to the DC motor 61. The CPU 21 detects the output result of the encoder 61A as a detection signal S. The printer 1 can detect the detection signal S without providing a separate sensor.

[0064] The CPU 21 executes print cycle correction, which corrects the printing operation at a predetermined cycle. The CPU 21 determines the relationship between the detection signal S and the fluctuation parameter Pth in synchronization with the predetermined cycle in which the printing operation is corrected. The printer 1 can reduce the load on the CPU 21 by synchronizing the determination of the relationship between the detection signal S and the fluctuation parameter Pth with the correction of the printing operation.

[0065] The CPU 21 calculates the Nth variable parameter Pth by multiplying the detected Nth detection signal S by a predetermined ratio. The printer 1 can calculate the variable parameter Pth by a simple calculation.

[0066] In the above description, the tape 101 and the ink ribbon 104 are examples of the "medium" of the present invention. The gear group 62, the drive transmission mechanism, the output gear 131, and the platen gear 83 are examples of the "drive gear" of the present invention. The CPU 21 is an example of the "control unit" of the present invention. The process of S9 executed by the CPU 21 is an example of the "detection process" of the present invention. The process of S23 executed by the CPU 21 is an example of the "calculation process" of the present invention. The process of S15 executed by the CPU 21 is an example of the "determination process" of the present invention. The process of S27 executed by the CPU 21 is an example of the "stop process" of the present invention. The process of S11 executed by the CPU 21 is an example of the "correction process" of the present invention.

[0067] The present invention is not limited to the above-described embodiments, and various modifications are possible. The techniques disclosed in the above-described embodiments and modifications can be combined to the extent that they are not inconsistent. The printer 1 is a thermal printer, but is not limited to this, and an inkjet printer may also be used. The printer 1 is battery-powered, but is not limited to this. An AC adapter may be used as an external power source. The present invention is also effective when the AC adapter deteriorates and the voltage drops.

[0068] In the above embodiment, the CPU 21 multiplied the Nth detection signal S by a predetermined ratio, but this is not limited to this. For example, the CPU 21 may calculate the N-1th variable parameter Pth by adding a predetermined additional value to the detected N-1th detection signal S. The printer 1 can calculate the variable parameter Pth through a simple calculation.

[0069] In the above embodiment, the detection signal S is the time required to detect 18 pulses of the encoder 61A, but this is not limited to this. For example, a sensor may be used to detect the detection signal S. The sensor is provided on the transport path of the tape 101 and detects the presence or absence of the tape 101. The sensor may be a transmissive or reflective sensor. The tape 101 has, for example, markers (e.g., marks, holes) arranged at predetermined intervals. In this case, the CPU 21 detects the period of marker detection by the sensor as the detection signal S. The printer 1 can accurately detect the detection signal S using the sensor.

[0070] In the above embodiment, the detection signal S and the fluctuation parameter Pth are based on the time to detect 18 pulses, but this is not limited to this. For example, the detection signal S and the fluctuation parameter Pth may be based on a pulse number other than 18 pulses. In other words, the pulse number may be less than 18 or more than 18. Therefore, they do not need to be synchronized with the printing cycle correction. Furthermore, the detection signal S and the fluctuation parameter Pth may be values based on the torque T or the rotation speed Rn. The predetermined ratio, additional value, etc. used in calculating the fluctuation parameter Pth may be changed as appropriate.

[0071] In the above embodiment, the first detection signal S is not the target for stopping the DC motor 61, but this is not limiting. For example, the first detection signal S may be compared with a predetermined threshold value Th.

[0072] In the above embodiment, the driving of the DC motor 61 is stopped when i=5, that is, when the detection signal S exceeds the fluctuation parameter Pth five times in a row, but this is not limited to this. For example, the DC motor 61 may be stopped when i is a positive number equal to or less than 4, or when i is a positive number equal to or greater than 6.

[0073] Instead of the CPU 21, an ASIC, an FPGA (Field Programmable Gate Array), or the like may be used as a processor. The main processing may be distributed among multiple processors. The printer 1 may also include other non-transitory storage media, such as an HDD. The non-transitory storage media may be any storage media capable of retaining information regardless of the period for which the information is stored. The non-transitory storage media does not have to include a temporary storage medium (for example, a transmitted signal).

[0074] The various programs may be downloaded (i.e., transmitted as a transmission signal) from a server connected to a network (not shown) and stored in a memory such as a HDD. In this case, the various programs may be stored in a non-transitory storage medium such as a HDD provided in the server. [Explanation of symbols]

[0075] 1. Printer 21 CPU 61 DC motor 61A Encoder 71 head 82 Platen roller 62, 83, 131 gears S detection signal Pth fluctuation parameters

Claims

1. A battery-powered printer, a head that prints on a medium using power from the battery; a platen roller for transporting the medium; a drive gear that drives the platen roller; a DC motor that rotates using power from the battery and drives the drive gear; Control unit and Equipped with The control unit a detection process of detecting a detection signal corresponding to the rotation speed of the DC motor N times (N is a positive number equal to or greater than 2); a calculation process for calculating an (N-1)th fluctuation parameter based on the (N-1)th detection signal detected by the detection process; a determination process for determining a relationship between the (N-1)th fluctuation parameter calculated by the calculation process and the Nth detection signal detected by the detection process; Run A printer characterized by:

2. The determination process includes: determining whether the detection signal exceeds the fluctuation parameter; The control unit a stop process for stopping the driving of the DC motor when it is determined by the determination process that the detection signal has exceeded the fluctuation parameter; Run the following again:

2. The printer according to claim 1.

3. The stop processing is When it is determined by the determination process that the detection signal has exceeded the fluctuation parameter multiple times in succession, the driving of the DC motor is stopped.

3. The printer according to claim 2.

4. The DC motor is provided with an encoder, The detection process detects the output result of the encoder as the detection signal.

2. The printer according to claim 1.

5. The control unit Correction process for correcting printing operations at a predetermined interval Run The determination process determines the relationship between the detection signal and the variable parameter in synchronization with the predetermined cycle in which the printing operation is corrected by the correction process.

2. The printer according to claim 1.

6. The calculation process includes: The N-1th fluctuation parameter is calculated by multiplying the N-1th detection signal detected by the detection process by a predetermined ratio.

2. The printer according to claim 1.

7. The calculation process includes: The N-1th fluctuation parameter is calculated by adding a predetermined addition value to the N-1th detection signal detected by the detection process.

3. The printer according to claim 2.

8. a sensor provided in a transport path of the medium; the medium has markings arranged at predetermined intervals; The detection process includes: The period during which the sensor detects the marker is detected as the detection signal.

2. The printer according to claim 1.

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