Printer, control method for thermal head, and program

Abstract

A printer according to one embodiment of the present invention comprises: a thermal head including a heat generation unit having a plurality of heat generation elements arranged in a line formation, and a drive circuit that drives the heat generation unit so as to control whether or not to energize each heat generation element of the heat generation unit in an energization period on the basis of a signal indicating the energization period of the heat generation unit in a printing period of one line; and a control unit that sets a voltage supply period which is a period for supplying a heat generation unit voltage to the thermal head according to the energization period, the heat generation unit voltage being the voltage for energizing the heat generation unit.

Description

Printer, thermal head control method, program

[0001] This invention relates to a printer that performs printing using a thermal head.

[0002] A thermal head is equipped with multiple heating elements, and a printer equipped with a thermal head is configured to print on the printing medium by selectively heating these multiple heating elements.

[0003] A thermal head is known to include multiple heating elements as well as a driver IC for controlling the power supply to each heating element (see, for example, Japanese Patent Publication No. 2009-190334).

[0004] Incidentally, if the driver IC mounted on the thermal head is subjected to external noise, the driver IC may enter a latch-up state. For example, near the thermal head, the printing medium and thermal transfer ink ribbon can become charged as they are transported within the printer, making the thermal head susceptible to noise caused by electrostatic discharge from the printing medium and ink ribbon. When the driver IC enters a latch-up state, it cannot be controlled from the outside, and the multiple heating elements corresponding to the driver IC continue to be energized, causing them to overheat. This can result in printing being darker than intended and ultimately leading to a break in the circuit.

[0005] Therefore, the present invention aims to improve the noise immunity of the thermal head in a printer.

[0006] One aspect of the present invention is a printer comprising: a thermal head having a heating section having a plurality of heating elements arranged in a line; a drive circuit that drives the heating section to control whether or not to energize each heating element of the heating section during the energizing period based on a signal indicating the energizing period of the heating section during the printing period of one line; and a control unit that sets a voltage supply period, which is the period during which the heating section voltage is supplied to the thermal head, according to the energizing period, when the voltage used to energize the heating section is the heating section voltage.

[0007] According to one aspect of the present invention, the noise immunity of the thermal head in a printer can be improved.

[0008] This is a schematic side view of a printer according to one embodiment. This is a schematic enlarged side view showing the parts related to printing by the printer shown in Figure 1A. This is a functional block diagram of a printer according to one embodiment. This is a functional block diagram showing the detailed configuration of the control unit in Figure 2. This is a schematic circuit diagram of a thermal head according to one embodiment. This is a schematic circuit diagram of a thermal head that includes multiple driver ICs. This is a diagram showing an example of the operation of a thermal head in a printer according to one embodiment. This is a diagram showing an example of the operation waveform of the strobe signal and the heating element voltage in Figure 6. This is a diagram showing an example of the operation of a thermal head in a printer according to one embodiment. This is a diagram showing an example of the operation of a thermal head in a printer according to one embodiment. This is a diagram showing an example of the operation waveform of the heating element voltage and the IC power supply voltage in Figure 9. This is a diagram showing an example of the operation of a thermal head in a printer according to one embodiment with different printing speeds in a printer according to one embodiment. This is a diagram showing an example of the operation of a printer according to one embodiment in which a stop process is performed after printing a label and the driver IC is reset. This is a diagram showing an example of the operation of a printer according to one embodiment in which a stop process is performed after the completion of one print job and the driver IC is reset.

[0009] The forms described below are not limited to those shown in the brief description of the drawings.

[0010] A first aspect of one aspect of the present invention is a printer comprising: a heating unit having a plurality of heating elements arranged in a line; a drive circuit that drives the heating unit to control whether or not to energize each heating element of the heating unit during the energizing period based on a signal indicating the energizing period of the heating unit during the printing period of one line; and a control unit that sets a voltage supply period, which is the period during which the heating unit voltage is supplied to the thermal head, according to the energizing period, when the voltage used to energize the heating unit is the heating unit voltage.

[0011] According to a first aspect of a certain embodiment of the present invention, the noise immunity of a thermal head can be improved.

[0012] A second aspect of a certain embodiment of the present invention is the printer according to the first embodiment, wherein the control unit sets the voltage supply period such that the energizing period is included in the voltage supply period.

[0013] According to a second aspect of a certain embodiment of the present invention, the voltage supply period can be appropriately set considering the delay in supplying the head operating voltage, etc.

[0014] A third aspect of a certain embodiment of the present invention is the printer according to the first or second embodiment, wherein the control unit sets the voltage supply period such that it starts a predetermined time before the start time of the energizing period and ends a predetermined time after the end time of the energizing period.

[0015] According to a third aspect of a certain embodiment of the present invention, the voltage supply period can be appropriately set considering the delay in supplying the head operating voltage, etc.

[0016] A fourth aspect of a certain embodiment of the present invention is the printer according to the first embodiment, wherein the control unit sets the voltage supply period so that the voltage supply period is synchronized with the energization period.

[0017] According to a fourth aspect of a certain embodiment of the present invention, the start and end of the supply of the head operating voltage can be made to coincide with the start and end of the energizing period.

[0018] A fifth aspect of a certain embodiment of the present invention is a printer according to any one of the first to fourth embodiments, wherein the control unit sets the voltage supply period such that, when the power supply period is set multiple times within the printing period of one line, the supply of the heating element voltage is started according to the start time of the first power supply period among the multiple power supply periods, and the supply of the heating element voltage is stopped according to the end time of the last power supply period.

[0019] According to a fifth aspect of a certain embodiment of the present invention, when multiple energizing periods are set, the head operating voltage can be reliably supplied during each energizing period.

[0020] A sixth aspect of a certain embodiment of the present invention is a printer according to any one of the first to fifth embodiments, wherein when the control unit starts driving the heat-generating part, it starts supplying a circuit voltage to operate the drive circuit before starting to supply the heat-generating part voltage, and when it stops driving the heat-generating part, it stops supplying the heat-generating part voltage before stopping the supply of the circuit voltage.

[0021] According to a sixth aspect of a certain embodiment of the present invention, it is possible to avoid a situation in which the heat-generating part is energized when no voltage is supplied to the signal generation part.

[0022] A seventh aspect of a certain embodiment of the present invention is a printer according to any one of the first to sixth embodiments, wherein the control unit controls the drive circuit to perform a stop process that resets the drive circuit by stopping the supply of an operating voltage for operating the drive circuit for a predetermined period of time.

[0023] According to a seventh aspect of a certain embodiment of the present invention, the noise immunity of the thermal head can be further improved.

[0024] An eighth aspect of a certain aspect of the present invention is a control method for a thermal head. The thermal head includes a heating section having a plurality of heating elements arranged in a line, and a drive circuit that drives the heating section to control whether or not to energize each heating element of the heating section during the energizing period, based on a signal indicating the energizing period of the heating section during the printing period of one line. The control method includes the steps of supplying the signal indicating the energizing period to the thermal head, and setting a voltage supply period, which is the period during which the heating section voltage is supplied to the thermal head, according to the energizing period, when the voltage used to energize the heating section is the heating section voltage.

[0025] According to an eighth aspect of a certain embodiment of the present invention, the noise immunity of a thermal head can be improved.

[0026] A ninth aspect of an embodiment of the present invention is a program that causes a computer to execute a predetermined procedure in a printer having a thermal head. The thermal head includes a heating portion having a plurality of heating elements arranged in a line, and a drive circuit that drives the heating portion to control whether or not to energize each heating element of the heating portion during the energization period based on a signal indicating the energization period of the heating portion during one line printing period. The predetermined procedure includes a procedure of supplying a signal indicating the energization period to the thermal head, and a procedure of setting a voltage supply period, which is a period of supplying the heating portion voltage to the thermal head when the voltage for energizing the heating portion is defined as the heating portion voltage, according to the energization period.

[0027] According to the ninth aspect of an embodiment of the present invention, the noise resistance of the thermal head can be improved.

[0028] Hereinafter, the printer 1 according to the embodiment will be described in detail with reference to the drawings. FIG. 1A is a side view of a main part of the printer 1 with the interior visible. FIG. 1B is a side view schematically showing an enlarged view of a part related to printing by the printer 1 shown in FIG. 1A. The printer 1 is a thermal printer that prints information such as characters, symbols, graphics, or codes on a label having a heat-sensitive coloring layer on one side. As shown in FIG. 1A, a paper supply unit 9, a head unit 5, and an ink ribbon unit 12 are installed inside the printer 1. The printer 1 is provided with an openable and closable printer cover (not shown), but FIG. 1A shows the state with the printer cover removed.

[0029] The paper supply unit 9 is loaded with a roll paper R. The roll paper R is formed by winding a belt-like continuous paper CP in a roll shape. The roll paper R can be replaced by opening a printer cover (not shown). Although not shown, in one embodiment, the continuous paper CP has, for example, a belt-like backing paper and a plurality of labels temporarily attached at predetermined intervals on the backing paper. The label-attaching surface of the backing paper is coated with a release agent such as silicone so that each label can be easily peeled off. In another embodiment, the continuous paper CP may be a label without a backing paper.

[0030] As shown in FIG. 1B, in the printer 1, the platen roller 10 is supported in a state where it can rotate in both forward and reverse directions. The platen roller 10 is a conveying means for conveying the continuous paper CP drawn from the roll paper R. The rotation axis of the platen roller 10 extends along the width direction of the continuous paper CP. A gear (not shown) is provided at one end of the platen shaft of the platen roller 10, and this gear is mechanically connected to a stepping motor for roller drive (not shown). Based on a signal transmitted from a control unit described later, the stepping motor operates and the platen roller 10 rotates. During the period from when the continuous paper CP is drawn from the roll paper R until it is discharged from the issuing port 20, printing is performed on the labels on the continuous paper CP.

[0031] The ink ribbon unit 12 includes a ribbon supply unit 12a and a ribbon winding unit 12b, and supplies and winds up an ink ribbon RB coated with printing ink. The ribbon supply unit 12a supports the ink ribbon RB wound in a roll shape in a rotatable state. The ribbon winding unit 12b winds up and collects the printed ink ribbon RB. When using the ink ribbon RB, the ink ribbon RB drawn from the ribbon supply unit 12a is passed under the head unit 5 and wound up by the ribbon winding unit 12b.

[0032] The head unit 5 is installed inside the printer 1 in a state where it can be opened and closed, and includes a thermal head 15 for printing on labels. The thermal head 15 is a printing means for sequentially printing information on a plurality of labels on the continuous paper CP. As will be described later, the thermal head 15 includes a plurality of heating elements (heating resistors) arranged along the width direction of the continuous paper CP, and performs printing by selectively energizing the plurality of heating elements based on a signal transmitted from the control unit. When the heating elements of the thermal head 15 heated by current are pressed against the labels on the continuous paper CP through the ink ribbon RB, the printing ink of the ink ribbon RB melts and transfers to the labels, thereby printing information on the labels. The thermal head 15 will be described in more detail later.

[0033] Next, the internal configuration of printer 1 will be described with reference to Figure 2. Figure 2 is a block diagram showing the internal configuration of printer 1. As shown in Figure 2, printer 1 includes, for example, a control unit 11, a drive circuit 13, a motor 14, a thermal head 15, a power supply unit 16, and storage 18. The control unit 11 includes a processor and memory and controls various operations of printer 1. The processor reads and executes firmware stored in memory when printer 1 is started up. For example, the control unit 11 sends control signals to the drive circuit 13 for controlling the rotational movement of the motor 14 and sends data signals and control signals for printing to the thermal head 15. The control unit 11 performs the printing process by selectively controlling the flow of current to each of the multiple heating elements included in the thermal head 15 based on the image data to be printed. The image data is data obtained by drawing a file for printing as bitmap data. A detailed example of the configuration of the control unit 11 will be described later.

[0034] Storage 18 is a storage device such as an SSD (Solid State Drive). Storage 18 stores, for example, print files obtained from the host computer and print format information for printing information on each label. Drive circuit 13 is a circuit that drives a motor 14 that controls the rotation of the platen roller 10 in response to a transport request from the control unit 11. Clock pulse M_CLK is a pulse signal supplied from the control unit 11 to the drive circuit 13 in order to operate the motor 14. The motor 14 is, for example, a stepping motor and is mechanically connected to the platen roller 10. Transport requests include, for example, information on the transport direction (forward or reverse) and the transport amount (e.g., number of steps). Power supply unit 16 is connected to a commercial AC power supply and generates a DC reference voltage that serves as a reference for operating each part of the printer 1.

[0035] Next, the printing operation of printer 1 will be described with reference to Figures 3 and 4. Figure 3 is a functional block diagram showing the detailed configuration of the control unit 11 in Figure 2. Figure 4 is a schematic circuit diagram of the thermal head 15.

[0036] As shown in Figure 3, the control unit 11 includes a head controller 21, a memory 22, a heat generation unit 23, and an IC power generation unit 24. The head controller 21 controls the entire printing operation in the control unit 11. The head controller 21 supplies a clock pulse CLK, a data signal DATA, a latch pulse LATCH, and a strobe signal STB to the thermal head 15. The clock pulse CLK is the reference pulse used to operate the thermal head 15. In the printer 1, the start of the printing cycle is synchronized with the clock pulse M_CLK. In this sense, the thermal head 15 operates with the clock pulse M_CLK as the reference. The memory 22 is, for example, RAM (Random Access Memory) and has an image buffer with a FIFO (First In First Out) configuration. Image data is stored in the image buffer. The image data is dot-level data of the entire image to be printed on a single label.

[0037] In one embodiment, the head controller 21 sequentially generates data signals DATA based on line-by-line image data (line data). The data signals DATA are signals indicating whether or not to energize the corresponding heating element for each dot in a line within the energizing period defined by the strobe signal STB (data indicating "energetic" or "non-energetic"). In some cases, only one strobe signal STB may be set during the printing period of one line, while in other cases, multiple strobe signals STB may be set. For example, when printing is performed by thermal history control, multiple strobe signals STB may be set during the printing period of one line (hereinafter also referred to as the "printing cycle") in order to precisely control the energizing period and timing during the printing period of one line.

[0038] When one strobe signal STB is set during the printing cycle (hereinafter referred to as "single strobe"), the data signal DATA is a signal indicating whether or not to energize each heating element during the energizing period defined by the single strobe signal STB. In one embodiment, the strobe signal STB is a signal that becomes energized when it is at an L level (low active). When multiple strobe signals STB are set during the printing cycle (hereinafter referred to as "multi-strobe"), the data signal DATA is a signal indicating whether or not to energize each heating element during each of the energizing periods defined by each of the multiple strobe signals STB.

[0039] As shown in Figure 3, the control unit 11 includes a heat-generating unit 23 and an IC power-generating unit 24. The heat-generating unit 23 and the IC power-generating unit 24 each include a boost circuit and / or a buck circuit. The heat-generating unit 23 generates a voltage V1 for energizing the heat-generating unit 40 (see Figure 4) of the thermal head 15 based on a reference voltage generated by the power supply unit 16. The voltage V1 is, for example, 19 to 24V. The IC power-generating unit 24 generates a voltage V2 for operating the driver IC 30 (see Figure 4) of the thermal head 15 based on a reference voltage generated by the power supply unit 16. The voltage V2 is, for example, 3.3 to 5V.

[0040] As shown in Figure 3, the control unit 11 has a switch SW1 provided between the heat generation unit 23 and the thermal head 15, and a switch SW2 provided between the IC power generation unit 24 and the thermal head 15. Switches SW1 and SW2 may each be composed of transistors. The head controller 21 controls the conduction state of switch SW1 with the control signal CTRL1 to set the heat generation unit voltage VH to voltage V1 or 0V. When the heat generation unit voltage VH is voltage V1, the voltage required to energize the heat generation unit 40 of the thermal head 15 is substantially supplied to the thermal head 15. In the following description, setting the heat generation unit voltage VH to voltage V1 is equivalent to supplying the heat generation unit voltage VH to the thermal head 15. The head controller 21 controls the conduction state of switch SW2 with the control signal CTRL2 to set the IC power supply voltage Vdd to voltage V2 or 0V. When the IC power supply voltage Vdd is voltage V2, the voltage required to operate the driver IC 30 of the thermal head 15 is effectively supplied to the thermal head 15. In the following explanation, setting the IC power supply voltage Vdd to voltage V2 is equivalent to supplying the IC power supply voltage Vdd to the thermal head 15.

[0041] As shown in Figure 4, the thermal head 15 includes a driver IC 30 (an example of a drive circuit) and a heating unit 40. The heating unit 40 includes a plurality of heating elements (heating resistors) 40_1, 40_2, ..., 40_n arranged in a line. The driver IC 30 operates to selectively supply current to each heating element of the heating unit 40 (i.e., selectively energize each heating element) based on various signals supplied from the head controller 21.

[0042] The driver IC 30 includes a shift register (S / R) 31 for temporarily storing one line of data signal DATA in synchronization with the clock pulse M_CLK, a latch circuit (L) 32, an inverter 33, a NAND gate section 34, and a switch section 35. The data corresponding to each dot of one line of data signal DATA is bit data for each power-on period ("powered": H (High) level, "not powered": L (Low) level). The latch circuit 32 is connected in parallel with the shift register 31 and, in response to the latch pulse LATCH, simultaneously and in parallel transfers and holds each bit data of the data signal DATA stored in the shift register 31. This allows the data signal DATA corresponding to the next power-on period to be input to the shift register 31 even during the power-on period.

[0043] The NAND gate section 34 includes a plurality of NAND gates 34_1, 34_2, ..., 34_n, each corresponding to a bit of data in one line of data signal DATA. Each NAND gate in the NAND gate section 34 outputs a negative logical AND of the corresponding bit data in the data signal DATA and the inverted signal of the strobe signal STB. The strobe signal STB is a low-active signal that is energized when it is at a low level. Therefore, each NAND gate outputs an L level when the corresponding bit data in the data signal DATA is at a high level ("energized") and the strobe signal STB is at a low level. The switch section 35 includes a plurality of switches 35_1, 35_2, ..., 35_n, each corresponding to the NAND gates 34_1, 34_2, ..., 34_n. When the output of a NAND gate is at a low level, the corresponding switch is turned ON. Each switch in the switch section 35 can be made of, for example, a transistor.

[0044] With the above configuration, during the energizing period when the strobe signal STB is at the L level, if the bit data corresponding to a specific dot in the data signal DATA for one line is at the H level, the corresponding switch in the switch unit 35 turns ON and energizes the heating element. The output signals of each NAND gate in the NAND gate unit 34 are examples of signals that control whether or not to energize each heating element in the heating unit 40 during the energizing period. As will be described later, if the supply of the heating element voltage VH and / or IC power supply voltage Vdd is stopped by the head controller 21, even if the switch in the switch unit 35 is turned ON, the corresponding heating element will not be energized.

[0045] It should be noted that the thermal head 15 can also be operated using a logic configuration other than the one shown in Figure 4. For example, if we assume that, unlike the above, the strobe signal STB is a signal that is energized when it is at a high level, then instead of the NAND gate section 34, an AND gate section consisting of multiple AND gates may be provided, and the strobe signal STB may be directly input to each AND gate without going through the inverter 33. In that case, the switches corresponding to the output of each AND gate are configured to turn ON when the output of the AND gate is at a high level. As a result, during the energized period when the strobe signal STB is at a high level, if the bit data corresponding to a specific dot in the data signal DATA for one line is at a high level, the corresponding switch in the switch section 35 turns ON and the heating element is energized.

[0046] In Figure 4, one driver IC 30 is configured to process the heating elements for one line, but this is not limited to this configuration. Multiple driver ICs may be used to distribute the processing of the heating elements for one line. Figure 5 is a schematic circuit diagram of a thermal head that includes multiple driver ICs. In the example shown in Figure 5, the thermal head includes six driver ICs 30_1, 30_2, ..., 30_6. Each of the driver ICs 30_1, 30_2, ..., 30_6 corresponds to a group of heating elements G1, G2, ..., G6, and performs the process of selectively energizing each heating element included in the corresponding group. For example, if one line consists of 864 dots, each driver IC is responsible for processing the group of heating elements (containing 144 heating elements) corresponding to 144 dots. The head controller 21 divides the data signal DATA for one line into data signals DATA1, DATA2, ..., DATA6, and supplies each to six driver ICs 30_1, 30_2, ..., 30_6. The operation of each driver IC is the same as that shown in the configuration in Figure 4.

[0047] If the driver ICs shown in Figures 4 and 5 are subjected to external noise, the driver ICs may enter a latch-up state. For example, if driver IC 30 enters a latch-up state, the power supply to the multiple heating elements corresponding to driver IC 30 will continue, resulting in an overpowered state where each heating element continues to generate heat. This can cause the printed lines to become darker than intended, potentially leading to a break in the line. Therefore, in one embodiment, the head controller 21 sets a heating element voltage supply period in the printing cycle (printing period of one line) during which it supplies the heating element voltage VH according to the power supply period required for printing. In one embodiment, the head controller 21 also sets an IC power supply voltage supply period in the printing cycle during which it supplies the IC power supply voltage Vdd according to the power supply period. Both the heating element voltage supply period and the IC power supply voltage supply period, or either one, may be set according to the power supply period. As shown in Figure 3, the heating element voltage supply period and the IC power supply voltage supply period are set by the head controller 21 controlling switches SW1 and SW2, respectively.

[0048] Below, several specific examples in which both or either the heat-generating element voltage supply period and the IC power supply voltage supply period are set according to the energizing period will be described with reference to Figures 6 to 11.

[0049] (A-1) First Operation Example of Single Strobe Figure 6 is a timing chart showing a first operation example when the thermal head 15 is operated in single strobe mode. In one embodiment, the clock pulse M_CLK that operates the motor 14 is used as the reference pulse when performing printing operations in the printing cycle. In this operation example, the printing cycle corresponds to two cycles of the clock pulse M_CLK. In the timing chart of Figure 6, the data signal DATA is supplied to the shift register 31 with the clock pulse M_CLK as the reference. This data signal DATA is transferred to the latch circuit 32 and held when the latch pulse LATCH changes to L level. At the start of the printing cycle, the heating element voltage VH is 0V. Then, the strobe signal STB becomes L level in response to the latch pulse LATCH, and the energization period T ＳＴＢ The following is set. In response to the latch pulse LATCH, the heat-generating part voltage VH becomes voltage V1, and the heat-generating part voltage supply period T ＶＨ This is set. During the energizing period, each heating element of the heating section 40 (Figure 4) becomes energizable. Energizing period T ＳＴＢ In this configuration, the heating element of the heating unit 40 is selectively energized according to the data signal DATA.

[0050] In the example shown in Figure 6, the heating element voltage VH is not always set to voltage V1 during the printing cycle (i.e., the heating element voltage is supplied throughout the entire period), but rather the heating element voltage supply period T ＶＨ During the power supply period T ＳＴＢ The settings are configured accordingly. Therefore, even if the driver IC 30 enters a latch-up state, an overpower condition where power continues to be supplied to multiple heat-generating elements and they continue to generate heat is avoided.

[0051] Figure 7 is an enlarged view of the operating waveforms of the strobe signal STB and the heating element voltage VH when the strobe signal STB is at the L level in Figure 6. As shown in Figure 7, during the energizing period T ＳＴＢ The period during which the voltage is supplied to the heating element is TＶＨ As included, the heating element voltage supply period T ＶＨ is set. In one embodiment, as shown in FIG. 7, the energization period T ＳＴＢ The heating element voltage supply period T ＶＨ is started before a predetermined time Δt1 at the start time of ＳＴＢ and the heating element voltage supply period T ＶＨ is set so that it ends after a predetermined time Δt2 after the end time of the energization period T ＶＨ In this case, the predetermined times Δt1 and Δt2 are set in the head controller 21 in advance. By providing the predetermined times Δt1 and Δt2, the heating element voltage supply period T ＶＨ can be appropriately set in consideration of the delay times of the rise (0 → V1) and fall (V1 → 0) of the heating element voltage VH. When the delay times of the rise and fall of the heating element voltage VH are negligibly short, the heating element voltage supply period T ＶＨ may be set to be synchronized with the energization period T ＳＴＢ (that is, T ＶＨ = T ＳＴＢ ).

[0052] (A-2) Second operation example of single stroke FIG. 8 is a timing chart showing a second operation example when the thermal head 15 is operated in a single stroke. In the operation example shown in FIG. 8, the operation of the IC power supply voltage Vdd is different from that in FIG. 6. That is, instead of always setting the IC power supply voltage Vdd to the voltage V2 during the printing cycle (that is, making it the IC power supply voltage supply period throughout), the IC power supply voltage supply period T Ｖｄｄ is set according to the energization period T ＳＴＢ . Specifically, when the strobe signal STB becomes the H level and the energization period T ＳＴＢ ends, or after the end time of the energization period T ＳＴＢ , the IC power supply voltage Vdd is set to 0V. In this case, it is preferable to set the IC power supply voltage Vdd to 0V after a predetermined time of the heating element voltage supply period T ＶＨ . In the operation example shown in FIG. 8, even if the driver IC 30 enters a latch-up state, the driver IC 30 is reset after the end of the energization period and the malfunction is eliminated. Therefore, thereafter, the driver IC 30 operates normally.​

[0053] (A-3) First Operation Example of Multi-Strobing Figure 9 is a timing chart showing a first operation example when the thermal head 15 is operated in multi-strobe mode. With multi-strobe mode, the heat generated from the heating element can be dispersed within the printing cycle, making it possible to improve print quality compared to single-strobe mode. Figure 9 shows an example in which a power supply period T1 and multiple power supply periods T2 are provided by the strobe signal STB. In one embodiment, power supply period T1 is the main power supply period for printing, and power supply period T2 is a sub-power supply period for preheating, etc. Unlike in Figure 9, the sub-power supply periods may be set earlier than the main power supply period in the printing cycle.

[0054] In the timing chart of Figure 9, the data signal DATA includes data signal D1 corresponding to the energization period T1 and data signal D2 corresponding to multiple energization periods T2. The latch pulse LATCH includes latch pulse L1 corresponding to data signal D1 and latch pulse L2 corresponding to data signal D2.

[0055] First, a data signal D1 is supplied to the shift register 31 with respect to the clock pulse M_CLK. This data signal D1 is transferred to the latch circuit 32 and held when the latch pulse L1 changes to an L level. Next, the strobe signal STB becomes L level, and the energizing period T1 is set. During the energizing period T1, the heating elements of the heating unit 40 are selectively energized according to the data signal D1. After that, a data signal D2 is supplied to the shift register 31. This data signal D2 is transferred to the latch circuit 32 and held when the latch pulse L2 changes to an L level. Next, multiple energizing periods T2 are set. During each energizing period T2, the heating elements of the heating unit 40 are selectively energized according to the data signal D2.

[0056] In the example shown in Figure 9, the heating element voltage VH is not always set to voltage V1 during the printing cycle (i.e., the heating element voltage is supplied for the entire printing cycle), but rather the heating element voltage supply period T ＶＨThis is set according to the energizing periods T1 and T2. Therefore, even if the driver IC 30 enters a latch-up state, an overpower condition in which the energizing of multiple heating elements continues to generate heat is avoided. This effect is also achieved even if the IC power supply voltage Vdd is always supplied (a different case from Figure 9).

[0057] In one embodiment, as shown in Figure 9, the IC power supply voltage supply period T Ｖｄｄ This is set according to the energization period T2. Therefore, even if the driver IC 30 enters a latch-up state, the driver IC 30 is reset after the end of the energization period T2, resolving the malfunction, and thereafter the driver IC 30 operates normally. Note that in Figure 9, the heating element voltage supply period T ＶＨ and IC power supply voltage supply period T Ｖｄｄ This can be set after the transfer of data signals D1 and D2 is complete, or as a trigger using latch pulses L1 and L2.

[0058] Figure 10 is a magnified view showing the operating waveforms of the heating element voltage VH and IC power supply voltage Vdd when the IC power supply voltage Vdd becomes 0V in Figure 9. In one embodiment, as shown in Figure 10, the heating element voltage supply period T ＶＨ During the IC power supply voltage supply period T Ｖｄｄ The timing is set so that it is included in the heating element voltage supply period T. ＶＨ The IC power supply voltage supply period T is a predetermined time Δt3 before the start time. Ｖｄｄ The heating element voltage supply period T is initiated. ＶＨ After a predetermined time Δt4 from the end time, the IC power supply voltage supply period T Ｖｄｄ The IC power supply voltage supply period T is set to end. Ｖｄｄ This is set. In this case, the predetermined times Δt3 and Δt4 are set in advance in the head controller 21. By providing the predetermined times Δt3 and Δt4, the situation in which the heat-generating part 40 is energized when the IC power supply voltage Vdd is not supplied to the driver IC 30 is avoided, and the driver IC 30 can be properly protected.

[0059] (A-4) Second Operation Example of Multistrobe Figure 11 is a timing chart showing a second operation example when the thermal head 15 is operated in multistrobe mode. In the operation example shown in Figure 11, multiple energizing periods T1 and T2 are set within the printing cycle, similar to Figure 9, but the operation of the heating element voltage VH and IC power supply voltage Vdd is different from that in Figure 9. Specifically, the supply of the heating element voltage VH is started according to the start time of the first energizing period T1 among the multiple energizing periods, and the supply of the heating element voltage VH is stopped according to the end time of the last energizing period T2, so that the heating element voltage supply period T ＶＨ This is set. In this case, the heating element voltage supply period T ＶＨ This is set according to the initial energizing period T1. This setting takes into account the case where the intervals between adjacent energizing periods (between energizing period T1 and energizing period T2, and between adjacent energizing periods T2) are short. That is, if the setting is as shown in Figure 9, when the intervals between adjacent energizing periods are short, the heating element voltage VH may not reach voltage V1 by the start time of the energizing period, for example, due to the delay time of the rise and fall of the heating element voltage VH. Therefore, by setting it as shown in Figure 11, the heating element voltage VH can be reliably supplied during the energizing period.

[0060] As explained in the operation examples in Figures 6, 8, 9, and 11, in one embodiment of the printer 1, the head controller 21 sets the heating element voltage supply period and / or IC power supply voltage supply period according to the energizing period in the printing cycle of one line. For example, the heating element voltage VH and IC power supply voltage Vdd are turned ON / OFF in accordance with the ON / OFF state of the strobe signal STB that determines the energizing period. Therefore, even if the driver IC 30 of the thermal head 15 is subjected to external noise and enters a latch-up state, printing can continue while preventing the circuit of the heating element from being disconnected. In other words, the noise immunity of the thermal head 15 is improved.

[0061] As one embodiment, a control method for the thermal head 15 is disclosed. This control method includes the following steps (I) and (II). Also, as one embodiment, a program for causing a computer to perform the following steps (I) and (II) is disclosed. (I) A step of supplying a strobe signal indicating the energizing period to the thermal head 15. (II) A step of setting a voltage supply period, which is the period during which the heating element voltage VH is supplied to the thermal head 15, according to the energizing period. The above program can be executed by one or more processors. As one embodiment, the above program is stored in a non-temporary computer-readable recording medium.

[0062] Next, another control method by the head controller 21 will be described. In this alternative control method, the supply of the IC power supply voltage Vdd (an example of the operating voltage) that operates the driver IC 30 to the thermal head 15 is stopped for a predetermined period of time to perform a stop process that resets the driver IC 30. Even if the driver IC 30 enters a latch-up state, the driver IC 30 is reset by performing the above stop process, and an overpower condition in which power is continuously supplied to multiple heat-generating elements and heat continues to be generated can be avoided. The stop process is performed by the head controller 21 controlling switches SW1 and SW2 (see Figure 3), respectively. Below, an example of operation in which the stop process of stopping the supply of the IC power supply voltage Vdd for a predetermined period of time to reset the driver IC 30 is performed at least once within the printing period of one line will be described with reference to Figures 12 to 14.

[0063] (B-1) Single strobe operation example Figure 12 is a timing chart showing an example of operation when the thermal head 15 is operated in single strobe mode. In the operation example shown in Figure 12, the operation of the heating element voltage VH and the IC power supply voltage Vdd differs from that in Figure 6. That is, in Figure 12, the energizing period T ＳＴＢAfter the above is completed, the supply of the heat-generating element voltage VH is stopped for a predetermined period, and during the period when the supply of the heat-generating element voltage VH is stopped, a stop process Ps is performed to reset the driver IC 30 by stopping the supply of the IC power supply voltage Vdd for a predetermined period. Hereinafter, the period during which the supply of the heat-generating element voltage VH and the IC power supply voltage Vdd is stopped by the stop process Ps will be appropriately referred to as the "stop period". The length of the stop period for the heat-generating element voltage VH and the length of the stop period for the IC power supply voltage Vdd may be different. In the example operation shown in Figure 12, even if the driver IC 30 enters a latch-up state, the heat-generating element voltage VH is stopped, thus avoiding an overpower condition in which power is continuously supplied to multiple heat-generating elements and they continue to generate heat. In addition, by stopping the supply of the IC power supply voltage Vdd, the driver IC 30 is reset, and malfunctions of the driver IC 30 due to the latch-up state are resolved.

[0064] As shown in Figure 12, it is preferable to terminate the supply of the IC power supply voltage Vdd after the supply of the heat-generating part voltage VH has ended, and to start supplying the heat-generating part voltage VH after the supply of the IC power supply voltage Vdd has started. This prevents a situation in which the heat-generating part 40 is energized when the IC power supply voltage Vdd is not supplied to the driver IC 30, and the driver IC 30 can be properly protected. If the driver IC 30 has high tolerance, during the shutdown period, the supply of the heat-generating part voltage VH may be maintained while only the supply of the IC power supply voltage Vdd is stopped.

[0065] (B-2) Example of Multistrobe Operation Figure 13 is a timing chart showing an example of operation when the thermal head 15 is operated in multistrobe mode. In Figure 13, as in Figure 12, the printing period corresponds to two cycles of the clock pulse M_CLK. In the timing chart of Figure 13, the data signal DATA includes data signal D1 corresponding to the energization period T1 and data signal D2 corresponding to multiple energization periods T2. The latch pulse LATCH includes latch pulse L1 corresponding to data signal D1 and latch pulse L2 corresponding to data signal D2.

[0066] First, a data signal D1 is supplied to the shift register 31 with respect to the clock pulse M_CLK. This data signal D1 is transferred to the latch circuit 32 and held when the latch pulse L1 changes to an L level. Next, the strobe signal STB becomes L level, and the energizing period T1 is set. During the energizing period T1, the heating elements of the heating unit 40 are selectively energized according to the data signal D1. After that, a data signal D2 is supplied to the shift register 31. This data signal D2 is transferred to the latch circuit 32 and held when the latch pulse L2 changes to an L level. Next, multiple energizing periods T2 are set. During each energizing period T2, the heating elements of the heating unit 40 are selectively energized according to the data signal D2. After the last power-on period T2 ends, similar to the single-strobe case in Figure 12, the supply of the heating element voltage VH is stopped for a predetermined period, and during the period when the supply of the heating element voltage VH is stopped, a stop process Ps is performed to reset the driver IC 30 by stopping the supply of the IC power supply voltage Vdd for a predetermined period. In other words, when multiple power-on periods are set within the printing cycle, the head controller 21 controls the system to perform the stop process Ps after the end of the last power-on period among the multiple power-on periods.

[0067] In the operation example shown in Figure 13, the same effect as in the single strobe case in Figure 12 is obtained. That is, even if the driver IC 30 enters a latch-up state, the heating element voltage VH is stopped, thus avoiding an overpower condition in which power continues to be supplied to multiple heating elements and they continue to generate heat. In addition, by stopping the supply of the IC power supply voltage Vdd, the driver IC 30 is reset, and malfunctions of the driver IC 30 due to the latch-up state are eliminated.

[0068] In the operation example shown in Figure 13, when adjusting the print speed, the operation of the print cycle shown in Figure 13 should be repeated multiple times according to the print speed. That is, if the operation of the print cycle shown in Figure 13 is used as the basic operation, when performing processing at a lower print speed than in Figure 13, it is advisable to configure the system to repeat the basic operation shown in Figure 13 two or more times. Figure 14 shows operation examples for high and low print speeds. In Figure 14, the operation at a high print speed shows the same basic operation as in the operation example in Figure 13. In Figure 14, when the print speed is low, for example, the system is configured to repeat the basic operation twice. As shown in Figure 14, in the basic operation (operation at a high print speed), the stop process Ps is performed once, whereas in the case of a low print speed, the stop process Ps is performed multiple times (twice in the example of Figure 14). Since the operation at a low print speed is performed by repeating the basic operation, the system is controlled so that the multiple stop processes Ps are performed at equal intervals. In other words, if one or more stop processes Ps are performed within a printing cycle, the slower (lower) the printing speed, the more stop processes Ps can be provided within the printing cycle. Providing a larger number of stop processes Ps within the printing cycle has the advantage of reducing the time the heat-generating unit 40 is in an overpowered state.

[0069] In the basic operation with a high printing speed, a stop period is provided within the printing cycle after the power-on period (the last power-on period in the example of Figure 13) due to a stop process Ps. When this power-on period and stop period are considered as one set period, if the basic operation is repeated multiple times within the printing cycle (when the printing speed is relatively low), the system is configured so that there are N sets of periods (where N is an integer of 1 or more) within that printing cycle. This has the advantage of allowing the number of sets of periods to be configured as an integer multiple according to the printing speed, thus enabling efficient setting of processing within the printing cycle.

[0070] When adjusting the printing speed, the practice of repeating the basic operation multiple times within the printing cycle according to the printing speed can also be applied to the operation examples in Figures 6, 8, 9, 11, and 12.

[0071] The system may be controlled to perform a stop process that resets the driver IC 30 by stopping the supply of the IC power supply voltage Vdd for a predetermined period of time, at least once for printing one label, or at least once for printing by one print job.

[0072] Figure 15 shows an example of operation in printer 1 where a stop process is performed after printing a label to reset the driver IC 30. In the example shown in Figure 15, at the time when the printing period for the Nth label ends, the supply of the heating element voltage VH is stopped for a predetermined period, and during the period when the supply of the heating element voltage VH is stopped, a stop process Ps is performed in which the supply of the IC power supply voltage Vdd is stopped for a predetermined period. Similarly, a stop process Ps is performed after the printing period for the N+1th label ends. By performing the stop process Ps at least once for each label printed, even if a label cannot be printed normally due to a malfunction of the driver IC 30, the driver IC 30 is reset before the start of printing the next label, and the next label can be printed normally.

[0073] Figure 16 shows an example of operation in printer 1 where a stop process is performed after the completion of one print job to reset the driver IC 30. In the example shown in Figure 16, at the time when the printing period of the Nth print job ends, the supply of the heating element voltage VH is stopped for a predetermined period, and during the period when the supply of the heating element voltage VH is stopped, a stop process Ps is performed in which the supply of the IC power supply voltage Vdd is stopped for a predetermined period. By performing the stop process Ps at least once for printing by one print job, even if the labels are not printed correctly in a print job (for example, a print job that prints 10 labels) due to a malfunction of the driver IC 30, the driver IC 30 is reset before the start of printing by the next print job, and the next print job will be able to print correctly from the first label.

[0074] As illustrated in the operation examples in Figures 12 to 16, in one embodiment of the printer 1, the head controller 21 controls the system to perform a stop process once, which involves stopping the supply of the IC power supply voltage Vdd to the thermal head 15 for a predetermined period of time to reset the driver IC 30. By performing such a stop process, even if the driver IC 30 enters a latch-up state due to noise, the driver IC 30 is reset, resolving the malfunction of the driver IC 30 associated with the latch-up state. In other words, the noise immunity of the thermal head 15 is improved.

[0075] As shown in Figure 15, the head controller 21 may be controlled to perform the stop process Ps after printing on a label is finished and before printing on the next label begins. Performing this inter-label stop process can further improve the noise immunity of the thermal head 15. The inter-label stop process may be performed in place of, or together with, the stop process within the printing cycle shown in Figures 12 and 13.

[0076] In one embodiment, the head controller 21 may stop supplying the heat-generating element voltage VH and the IC power supply voltage Vdd when the printer cover (not shown) changes from a closed state to an open state, and start supplying the heat-generating element voltage VH and the IC power supply voltage Vdd when the printer cover changes from an open state to a closed state.

[0077] As one embodiment, a control method for the thermal head 15 is disclosed. This control method includes the following steps (I) and (II). Also, as one embodiment, a program for causing a computer to perform the following steps (I) and (II) is disclosed. (I) A step of supplying a strobe signal indicating the energizing period to the thermal head 15. (II) A step of controlling the computer to perform a stop process to reset the driver IC 30 by stopping the supply of the operating voltage that operates the driver IC 30 for a predetermined period. The above program can be executed by one or more processors. As one embodiment, the above program is stored in a non-temporary computer-readable recording medium.

[0078] Although several embodiments of the printer, thermal head control method, and program of the present invention have been described above, the present invention is not limited to the above embodiments. Furthermore, the above embodiments and technical matters can be combined as appropriate without departing from the spirit of the present invention.

[0079] This invention relates to the patent application 2024-223831 filed with the Japan Patent Office on 19 December 2024, and the patent application 2025-191682 filed with the Japan Patent Office on 12 November 2025, the contents of which are incorporated by reference in the specification of this application.

Claims

A heating section having multiple heating elements arranged in a line, A thermal head having a drive circuit that drives the heating element to control whether or not to energize each heating element of the heating element during the energizing period, based on a signal indicating the energizing period of the heating element during the printing period of one line, When the voltage used to energize the heating element is defined as the heating element voltage, a control unit sets the voltage supply period, which is the period during which the heating element voltage is supplied to the thermal head, according to the energization period. A printer equipped with [a specific feature / feature]. 　 The control unit sets the voltage supply period such that the energizing period is included in the voltage supply period. The printer according to claim 1. 　 The control unit sets the voltage supply period such that the voltage supply period starts a predetermined time before the start time of the energizing period and ends a predetermined time after the end time of the energizing period. The printer according to claim 1. 　 The control unit sets the voltage supply period so that the voltage supply period is synchronized with the energization period. The printer according to claim 1. 　 The control unit sets the voltage supply period such that, if the power supply period is set multiple times within the printing period of one line, the supply of the heating element voltage starts according to the start time of the first power supply period among the multiple power supply periods, and the supply of the heating element voltage ends according to the end time of the last power supply period. The printer according to claim 1. 　 The control unit, When starting to drive the heat-generating part, the supply of the circuit voltage that operates the drive circuit is started first, and then the supply of the heat-generating part voltage is started. When terminating the operation of the heat-generating part, the supply of voltage to the heat-generating part is terminated first, and then the supply of voltage to the circuit is terminated. The printer according to claim 1. 　 The control unit controls the drive circuit to perform a stop process that resets the drive circuit by stopping the supply of the operating voltage for operating the drive circuit for a predetermined period of time. A printer according to any one of claims 1 to 6. A control method for a thermal head, The thermal head is A heating section having multiple heating elements arranged in a line, The device includes a drive circuit that drives the heating element to control whether or not to energize each heating element of the heating element during the energizing period, based on a signal indicating the energizing period of the heating element during the printing period of one line. The control method described above is The steps include supplying a signal indicating the energization period to the thermal head, The step includes setting a voltage supply period, which is the period during which the voltage used to energize the heating element is supplied to the thermal head, according to the energization period, when the voltage used to energize the heating element is defined as the heating element voltage. A control method for thermal heads. 　 A program for a printer having a thermal head that causes a computer to perform a predetermined procedure, The thermal head is A heating section having multiple heating elements arranged in a line, The device includes a drive circuit that drives the heating element to control whether or not to energize each heating element of the heating element during the energizing period, based on a signal indicating the energizing period of the heating element during the printing period of one line. The aforementioned prescribed procedure is, A procedure for supplying a signal indicating the energization period to the thermal head, The procedure includes setting the voltage supply period, which is the period during which the voltage used to energize the heating element is supplied to the thermal head, according to the energization period, when the voltage used to energize the heating element is defined as the heating element voltage. program.

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