Printing apparatus and

Abstract

To provide a printer capable of stably executing a function.SOLUTION: The printing apparatus 1A includes an 1USB port 11, an 2USB port 12, a functional section 60, a first supply circuit 70, and a voltage difference adjustment section 40A. The first 1USB port 11 receives a first power 190 from a first power source 101. The first 2USB port 12 receives a second power 290 from a second power source 201. The functional unit 60 executes the function of the printing apparatus 1A. The first supply circuit 70 connects the first 1USB port 11 and the second 2USB port 12 to the functional unit 60 in parallel. The voltage difference regulating unit 40A regulates a voltage difference between the voltage of the first electric power 190 and the voltage of the second electric power 290.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] The image processing device described in Patent Document 1 has a first USB connection unit and a second USB connection unit that establish a connection in accordance with the USBPD (Universal Serial Bus Power Delivery) standard. The first USB connection unit connects to a first external device and receives power from the first external device. The second USB connection unit connects to a second external device and receives power from the second external device. The image processing device receives power via either the first USB connection unit or the second USB connection unit and executes various functions of the image processing device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-133660 Summary of the Invention [Problem to be solved by the invention]

[0004] When the power received from the first USB connector is insufficient to execute a function, the image processing device switches from receiving power via the first USB connector to receiving power via the second USB connector. However, when switching from receiving power via the first USB connector to receiving power via the second USB connector, there may be a momentary interruption in the power supply. In this case, the image processing device may not be able to stably execute the function.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a printing device that can stably execute its functions. [Means for solving the problem]

[0006] The printing device of the present invention is characterized by comprising a first power receiving unit that receives a first power from a first power source, a second power receiving unit that receives a second power from a second power source, a functional unit that performs the functions of the printing device, a first supply circuit that connects the first power receiving unit and the second power receiving unit in parallel to the functional unit, and a voltage difference adjustment unit in the first supply circuit that adjusts the voltage difference between the voltage of the first power and the voltage of the second power.

[0007] According to the present invention, the first supply circuit connects the first power receiving unit and the second power receiving unit in parallel to the functional unit. The functional unit is supplied with first and second powers in parallel. Here, when the first supply circuit supplies the first and second powers in parallel to the functional unit, a voltage difference between the voltage of the first power and the voltage of the second power may occur in the first supply circuit. In the printing device, the voltage difference adjustment unit adjusts the voltage difference in the first supply circuit, so that the first and second powers do not flow back in the first supply circuit. Therefore, the printing device can supply the first and second powers in parallel to the functional unit, and even if the connection to one of the first or second power sources is momentarily interrupted, the printing device's functions can be stably executed using the power received from the other of the first or second power sources.

[0008] In the present invention, the first power receiving unit may be a first USB port that receives the first power from the first power source via a connection compliant with the USB (Universal Serial Bus) standard, and the second power receiving unit may be a second USB port that receives the second power from the second power source via a connection compliant with the USB standard. This allows the voltages of the first power 190 and the second power 290 to be adjusted even when the printing device receives the first power and the second power via a connection compliant with the USB standard. Because the first power or the second power does not flow back through the first supply circuit, the printing device can stably perform its functions.

[0009] In the present invention, the printing device may further include a first transformer unit connected to the first USB port and transforming the voltage of the first power, and a second transformer unit connected to the second USB port and transforming the voltage of the second power, and the voltage difference adjustment unit may include an adjustment circuit that, based on the voltage difference, transforms the voltage of the first power using the first transformer unit or transforms the voltage of the second power using the second transformer unit. According to this, when there is a voltage difference between the voltage of the first power and the voltage of the second power, the adjustment circuit transforms the voltage of the first power using the first transformer unit or transforms the voltage of the second power using the second transformer unit. Therefore, even when there is a voltage difference between the voltage of the first power and the voltage of the second power, the printing device adjusts the voltage difference, and the first power and the second power are stably supplied in parallel to the functional units.

[0010] In the present invention, the first USB port may be connected to the first power source via a connection compliant with the USBPD (Power Delivery) standard, the second USB port may be connected to the second power source via a connection compliant with the USBPD standard, and the voltage difference adjustment unit may include a first controller that negotiates a combination of a voltage and a current of the first power with the first power source, a second controller that negotiates a combination of a voltage and a current of the second power with the second power source, and an overall controller that at least one of causing the first controller to negotiate with the first power source or causing the second controller to negotiate with the second power source based on the voltage difference. According to this, when there is a voltage difference between the voltage of the first power and the voltage of the second power, the overall controller performs at least one of negotiation by the first controller 21 or negotiation by the second controller 22. Therefore, even when there is a voltage difference between the voltage of the first power and the voltage of the second power, the printing device adjusts the voltage difference, and the first power and the second power are stably supplied in parallel to the functional unit.

[0011] In the present invention, the second USB port may further include a second supply circuit that is connected to the second power source through a connection compliant with the USBPD (Power Delivery) standard and supplies the first power received from the first USB port to the second USB port. In this configuration, the second supply circuit supplies the first power to the second USB port. Since the second USB port is connected to the second power source through a connection compliant with the USBPD standard, the printing device can supply power to the second power source through power supply compliant with the USBPD standard.

[0012] In the present invention, the functional unit may include a printing unit that prints on a medium, and the second supply circuit may include a switching unit that switches between supplying power to the second USB port and stopping the power supply, and the switching unit may stop supplying power to the second USB port when the first supply circuit supplies the first power and the second power in parallel to the printing unit. According to this, printing on a medium by the printing unit consumes a large amount of power among the functions executed by the printing device. In the printing device, when the first supply circuit supplies the first power and the second power in parallel to the printing unit for printing on a medium, the switching unit stops supplying power to the second USB port, thereby stopping the supply of power to the second power source. Because the second power is supplied to the printing unit in parallel with the first power, the printing device can stably print using the printing unit.

[0013] In the present invention, the first USB port may further include a first controller connected to the first power source via a connection compliant with the USBPD standard and negotiating a combination of voltage and current of the first power with the first power source, and the second supply circuit may include a switching unit that switches between supplying power to the second USB port and stopping power supply, and when the first controller receives a negotiation request from the first power source, the switching unit stops supplying power to the second USB port, and after the switching unit has stopped supplying power to the second USB port, the first controller may start negotiation with the first power source. According to this configuration, when a negotiation request is received from the first power source while power is being supplied to the second power source, the power supply to the second power source is stopped, so that the first power and the second power are supplied in parallel to the functional unit. In this state, the first controller negotiates with the first power source, so that at least the second power is supplied to the functional unit. Therefore, even if a negotiation request is received from the first power source while the printing device is supplying power to the second power source, it is possible to prevent a shortage of power supplied to the functional units.

[0014] In the present invention, the printing device may further include a display unit that displays, from among the plurality of functions, functions that can be executed according to the sum of the first power and the second power, whereby a user can check the display unit to see which of the plurality of functions can be executed according to the sum of the received first power and the second power.

[0015] In the present invention, the display unit may include a plurality of LEDs (Light Emitting Diodes), and the number of LEDs that light up may be changed depending on the executable functions. In this way, by checking the number of LEDs that light up, a user can easily check which of the multiple functions can be executed based on the total of the received first power and second power.

[0016] In the present invention, the display unit may include an LED that can emit light in multiple colors, and the color emitted by the LED may change depending on the executable functions. In this way, by checking the color emitted by the LED, a user can easily check which of the multiple functions can be executed using the total of the received first power and second power.

[0017] In the present invention, the printing device may further include an operation unit that accepts a selection operation of a function to be executed by the function unit from the functions displayed on the display unit, whereby the user performs a selection operation on the operation unit, allowing the printing device to execute a function desired by the user from among the multiple functions.

[0018] In the present invention, the printing device may further include a function control unit that controls the execution of the function based on the sum of the first power and the second power. In this case, the function control unit controls the execution of the function based on the sum of the first power and the second power, so that the printing device can execute the function according to the sum of the received first power and the second power without any effort on the part of the user.

[0019] In the present invention, the printing device does not need to have a battery that stores received power and supplies the stored power to the functional unit. In this case, the printing device supplies first power and second power in parallel to the functional unit. Even if the connection to one of the first power source or the second power source is momentarily interrupted, the printing device can supply power received from the other of the first power source or the second power source to the functional unit, eliminating the need to supply power from a battery to the functional unit. Therefore, the size of the printing device can be reduced by incorporating a battery. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 2 is a block diagram showing the electrical configuration of a printing device 1A. [Figure 2] FIG. 2 is a block diagram showing an electrical system of the printing device 1A. [Figure 3] FIG. 2 is a conceptual diagram of a function table 61. [Figure 4] FIG. 2 is a conceptual diagram of a function table 62. [Figure 5] FIG. 10 is a conceptual diagram of a function table 63. [Figure 6] FIG. 2 is a diagram illustrating a function display LED 15. [Figure 7] FIG. 2 is a diagram illustrating a supply display LED 16. [Figure 8] 10 is a flowchart of a main process. [Figure 9] 9 is a flowchart of the main processing following FIG. 8. [Figure 10] 10 is a flowchart of the main processing following FIG. 9. [Figure 11] 11 is a flowchart of the main processing following FIG. 8 and FIG. 10. [Figure 12] 10 is a flowchart of a power supply process executed in the main process. [Figure 13] 10 is a flowchart of an execution return process executed in the main process. [Figure 14] 1 is a table showing differences between the embodiments. [Figure 15] FIG. 2 is a block diagram showing the electrical configuration of printing devices 1B and 1C. [Figure 16] FIG. 2 is a block diagram showing an electrical system of the printing device 1B. [Figure 17] FIG. 2 is a block diagram showing the electrical system of a printing device 1C. [Figure 18] FIG. 2 is a block diagram showing the electrical configuration of a printing device 1D. [Figure 19] FIG. 2 is a block diagram showing the electrical system of the printing device 1D. [Figure 20] FIG. 2 is a block diagram showing the electrical configuration of a printing device 1E. [Figure 21] FIG. 2 is a block diagram showing the electrical system of the printing device 1E. [Figure 22] FIG. 2 is a block diagram showing the electrical configuration of the printing device 1F. [Figure 23] FIG. 2 is a block diagram showing the electrical system of the printing device 1F. DETAILED DESCRIPTION OF THE INVENTION

[0021] First Embodiment A printing device 1A according to a first embodiment of the present invention will be described with reference to the drawings. 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 merely illustrative examples and are not intended to be limiting.

[0022] The configuration of printing device 1A will be described with reference to Figures 1 to 3. Printing device 1A is a thermal transfer printer that prints on a medium (not shown). Printing device 1A has a housing 2. On the surface of housing 2, an operation unit 18, a liquid crystal display 19, a first USB port 11, and a second USB port 12 are provided. Operation unit 18 is, for example, a keyboard, and accepts input operations from the user. Liquid crystal display 19 displays various information.

[0023] The first USB port 11 and the second USB port 12 are connectors conforming to the USB Type-C standard, for example. The first USB port 11 and the second USB port 12 include a D+ pin, a D- pin, a Vbus pin, a CC pin, etc. The D+ pin and D- pin are used for data communication conforming to the USB standard. The Vbus pin is used to receive power. The CC pin is used for negotiation, which will be described later.

[0024] A first power source 101 is connected to the first USB port 11 via a USB hub 110. The USB hub 110 has multiple USB ports. The first power source 101 is, for example, a personal computer, and is supplied with power from a commercial power source. The printing device 1A performs data communication with the first power source 101 in accordance with the USB standard and receives power in accordance with the USBPD standard. The first power source 101 is a source that supplies power to the printing device 1A.

[0025] A second power source 201 is connected to the second USB port 12. The second power source 201 is, for example, a smartphone or a general-purpose mobile battery, and is not connected to a commercial power source. The printing device 1A communicates with the second power source 201 using data in accordance with the USB standard and receives power in accordance with the USBPD standard. The second power source 201 switches between acting as a source that supplies power to the printing device 1A and a sink that receives power from the printing device 1A depending on its own stored power level.

[0026] The housing 2 houses the printing unit 13, driver 23, transport unit 14, driver 24, first controller 21, second controller 22, control board 99, system unit 90, adjustment circuit 30, and switches 81 to 87. The printing unit 13 is a thermal head including multiple heat generating elements, and performs printing on a medium. The driver 23 is connected to a CPU 91 (described later) via a bus 95, and drives the printing unit 13 under the control of the CPU 91. The transport unit 14 includes a motor and a platen roller (not shown), and transports the medium. The driver 24 is connected to the CPU 91 via the bus 95, and drives the transport unit 14 under the control of the CPU 91. The printing device 1A prints on the medium using the printing unit 13 while the transport unit 14 transports the medium.

[0027] When receiving power in accordance with the USBPD standard from the first power source 101 via the first USB port 11, the first controller 21 negotiates with the first power source 101. Negotiation is a process for setting, for example, which of the printing device 1A and the first power source 101 will be the source and which will be the sink, and setting the amount of power to be received. The negotiation is performed based on the resistance value of the CC pin.

[0028] When receiving power conforming to the USBPD standard from the second power source 201 via the second USB port 12, the second controller 22 negotiates with the second power source 201. The first controller 21 and the second controller 22 are connected to the CPU 91 via a bus 95, and negotiate under the control of the CPU 91.

[0029] The control board 99 controls the printing apparatus 1A and includes a CPU 91, a ROM 92, a RAM 93, and a storage device 94. The CPU 91 is a processor that executes various programs for controlling the printing apparatus 1A. The CPU 91 is connected via a bus 95 to the ROM 92, RAM 93, storage device 94, first controller 21, second controller 22, drivers 23-27, operation unit 18, adjustment circuit 30, and switches 81-87, which will be described later. The ROM 92 stores control programs and various setting information for executing main processing (see FIGS. 8-11), power supply processing (see FIG. 12), and execution return processing (see FIG. 13), which will be described later. The RAM 93 temporarily stores various information. The storage device 94 is non-volatile and stores function tables 61-63 (see FIGS. 3-5), which will be described later, and the like.

[0030] The system unit 90 is configured to display various information, and includes a function display LED 15, a supply display LED 16, and a liquid crystal display 19. The function display LED 15 is connected to a driver 25. The driver 25 drives the function display LED 15 under the control of the CPU 91. The supply display LED 16 is connected to a driver 26. The driver 26 drives the supply display LED 16 under the control of the CPU 91. Details of the function display LED 15 and the supply display LED 16 will be described later. The liquid crystal display 19 is connected to a driver 27. The driver 27 drives the liquid crystal display 19 under the control of the CPU 91. The drivers 25 to 27 are collectively referred to as a driver 28 (see Figure 2). The driver 28 drives the system unit 90.

[0031] The switches 81 to 87 are, for example, field effect transistors (FETs). The switches 81 to 87 and the adjustment circuit 30 will be described in detail later.

[0032] Referring to Figure 2, the power supply in the printing device 1A will be described. The printing device 1A receives power in accordance with the USBPD standard between the first power source 101 and the second power source 201. The printing device 1A does not have a battery that stores the received power and supplies it to the functions of the printing device 1A, nor does it have a DC connector for receiving power via a connection that does not comply with the USB standard. In other words, the printing device 1A operates only on the power supplied from the first power source 101 and the second power source 201.

[0033] The power supplied from the first power source 101 via the first USB port 11 is referred to as the first power 190. In the first embodiment, the magnitude of the first power 190 and the combination of voltage and current in the first power 190 are determined through negotiation between the first controller 21 and the first power source 101. The power supplied from the second power source 201 via the second USB port 12 is referred to as the second power 290. The magnitude of the second power 290 and the combination of voltage and current in the second power 290 are determined through negotiation between the second controller 22 and the second power source 201.

[0034] When the first power source 101 is connected to the first USB port 11 with the second power source 201 connected to the second USB port 12, the CPU 91 causes the first controller 21 to negotiate so that the voltage of the first power 190 is the same as the voltage of the second power 290. Similarly, when the second power source 201 is connected to the second USB port 12 with the first power source 101 connected to the first USB port 11, the CPU 91 causes the second controller 22 to negotiate so that the voltage of the second power 290 is the same as the voltage of the first power 190. In this way, when the first power 190 and the second power 290 are supplied simultaneously to the printing device 1A, the CPU 91 uses the first controller 21 or the second controller 22 to adjust the voltage of the first power 190 and the voltage of the second power 290 to be the same.

[0035] The first USB port 11 is connected to one end of a first transformer unit 31A. The first transformer unit 31A continuously transforms the voltage of the first power 190. The second USB port 12 is connected to a second transformer unit 32A. The second transformer unit 32A continuously transforms the voltage of the second power 290. The first transformer unit 31A and the second transformer unit 32A are, for example, DC-DC converters.

[0036] The other end of first transformer unit 31A is connected to power line 41. The other end of second transformer unit 32A is connected to power lines 42 and 43. Details of power line 43 will be described later. Power line 41 is connected to adjustment circuit 30, one end of switch 81, one end of switch 83, one end of switch 85, power line 74, and power line 75. Power line 42 is connected to adjustment circuit 30, one end of switch 82, switch 84, and switch 86, and power line 75.

[0037] The adjustment circuit 30 detects the voltage of the first power 190 and the voltage of the second power 290. If there is a difference between the detected voltage of the first power 190 and the voltage of the first power 190 received from the CPU 91, the adjustment circuit 30 outputs a signal to the first transformer unit 31A to correct the voltage difference. The first transformer unit 31A, which has received the signal, transforms the voltage of the first power 190 based on the received signal. If there is a difference between the detected voltage of the second power 290 and the voltage of the second power 290 received from the CPU 91, the adjustment circuit 30 outputs a signal to the second transformer unit 32A to correct the voltage difference. The second transformer unit 32A, which has received the signal, transforms the voltage of the second power 290 based on the received signal. The CPU 91 causes the first controller 21 and the second controller 22 to negotiate based on the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. Therefore, the voltage of the first power 190 on the power line 41 and the voltage of the second power 290 on the power line 42 are adjusted to be the same magnitude. In this way, the adjustment circuit 30 adjusts the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. The CPU 91, the first controller 21, the second controller 22, and the adjustment circuit 30 that adjust the voltage difference between the voltage of the first power 190 and the voltage of the second power 290 are collectively referred to as a voltage difference adjustment unit 40A.

[0038] The other ends of switches 81 and 82 are connected to power line 71. Power line 71 is connected to printing unit 13 via driver 23. The other ends of switches 83 and 84 are connected to power line 72. Power line 72 is connected to conveying unit 14 via driver 24. The other ends of switches 85 and 86 are connected to power line 73. Power line 73 is connected to system unit 90 via driver 28.

[0039] The printing unit 13, the transport unit 14, the control board 99, and the system unit 90 are collectively referred to as the functional unit 60. The functional unit 60 executes various functions of the printing device 1A. The power lines 41, 42, the switches 81-86, the power lines 71-73, 75, and a portion of the power line 74 that supply power to the functional unit 60 are collectively referred to as the first supply circuit 70. The first supply circuit 70 connects the first USB port 11 and the second USB port 12 in parallel to the functional unit 60. As a result, the first power 190 and the second power 290 are supplied in parallel to the functional unit 60.

[0040] The power line 74 is connected to one end of a switch 87. The other end of the switch 87 is connected to one end of the second transformer 32A. The power line 43, connected to the other end of the second transformer 32A, is connected to the second USB port 12. The power line 74, switch 87, and power line 43 are collectively referred to as a second supply circuit 49. The second supply circuit 49 supplies the first power 190 received from the first USB port 11 to the second USB port 12. The second USB port 12 receives power from a second power source 201 in accordance with the USBPD standard. That is, when the printing device 1A becomes the source supplying power to the second power source 201 through negotiation by the second controller 22, the printing device 1A supplies the first power 190 to the second power source 201 via the second USB port 12. The switch 87 switches between supplying the first power 190 to the second USB port 12 and stopping the power supply.

[0041] The power line 75 is connected to one end of the converter 29. The other end of the converter 29 is connected to the control board 99. The converter 29 steps down the voltage of the first power 190 and the voltage of the second power 290, and supplies the first power 190 and the second power 290 to the control board 99. The CPU 91, ROM 92, RAM 93, and storage device 94 of the control board 99 are driven by the first power 190 and the second power 290 supplied from the converter 29. The power line 75 is not provided with a switch for switching between supplying and stopping the first power 190 and the second power 290 to the converter 29. Therefore, the CPU 91, ROM 92, RAM 93, and storage device 94 start operating when power is supplied from at least one of the first power source 101 and the second power source 201.

[0042] 3 to 5, the relationship between the amount of power supplied and the executable functions of the printing device 1A will be described. The printing device 1A drives the functional unit 60 only with power supplied from the first power source 101 and the second power source 201. Therefore, in the printing device 1A, the content of some functions may be changed or the execution of some functions may be suspended depending on the amount of power supplied from the first power source 101 and the second power source 201. In the functional unit 60, the printing unit 13, the transport unit 14, and the system unit 90 consume the most power in this order. Note that the control board 99 and the system unit 90 can execute their functions with 2.5 W, which is the minimum power required for power supply conforming to the USB standard. The printing unit 13 and the transport unit 14 require more than 2.5 W to execute their functions.

[0043] Function tables 61-63 stored in storage device 94 show the relationship between the connection combinations of first USB port 11 and second USB port 12, the amount of power received from first USB port 11 and second USB port 12, and the executable functions of printing device 1A. For example, No. 1 in function table 61 of FIG. 3 indicates that printing device 1A receives power only from first USB port 11 and can execute all functions executable by functional unit 60 with power supplied from first power source 101. Functions marked with a "△" in function tables 61-63 indicate that the content of the function can be changed. For example, No. 2 in function table 61 of FIG. 3 changes the function of printing unit 13, and printing unit 13 prints on media at a slower speed than usual.

[0044] 4, when first power 190 and second power 290 are supplied in parallel to functional unit 60, the executable functions and the content of the functions to be executed are determined according to the combined magnitude of first power 190 and second power 290. As shown in function table 63 in FIG. 5, when power is supplied to second power source 201 via second USB port 12, only first power 190 is supplied to printing device 1A.

[0045] The function display LED 15 will be described with reference to FIG. 6. The function display LED 15 displays the functions of the printing device 1A that can be executed using the total power of the first power 190 and the second power 290. The function display LED 15 includes three LEDs 151, 152, and 153. The LEDs 151, 152, and 153 are, for example, full-color LEDs that can emit light in multiple colors. In FIG. 6, black indicates that the LEDs 151, 152, and 153 are off, a diagonal line sloping upward to the right indicates that the LEDs 151, 152, and 153 are lit orange, and white indicates that the LEDs 151, 152, and 153 are lit blue.

[0046] In the function display LED 15, LEDs 151, 152, and 153 each correspond to a function of the printing device 1A. The function display LED 15 displays the functions of the printing device 1A that can be executed with the total power of the first power 190 and the second power 290 by the colors emitted by the LEDs 151, 152, and 153.

[0047] LED 151 corresponds to the printing function of printing device 1A. When LED 151 is lit blue, it indicates that printing device 1A can perform normal printing using printing unit 13. When LED 151 is lit orange, it indicates that printing device 1A can perform printing at a slower speed than normal using printing unit 13. When LED 151 is off, it indicates that printing device 1A cannot perform printing using printing unit 13.

[0048] The LED 152 corresponds to the transport function of the printing device 1A. When the LED 152 is lit blue, this indicates that the printing device 1A can transport a medium using the transport unit 14. When the LED 152 is off, this indicates that the printing device 1A cannot transport a medium using the transport unit 14. Note that in this embodiment, the LED 152 does not light up orange.

[0049] The LED 153 corresponds to the charging function of the printing device 1A. When the LED 153 lights up blue, it indicates that the printing device 1A can quickly charge the second power source 201. When the LED 153 lights up orange, it indicates that the printing device 1A can slowly charge the second power source 201. When the LED 153 is off, it indicates that the printing device 1A cannot charge the second power source 201. Note that since the system unit 90 can run with the minimum power required for power supply in accordance with the USB standard, the system unit 90 becomes operational when the first power source 101 or the second power source 201 is connected to the printing device 1A. Therefore, in this embodiment, LEDs corresponding to the control functions of the printing device 1A are not included in the function display LEDs 15.

[0050] The supply indicator LED 16 will be described with reference to FIG. 7. The supply indicator LED 16 displays the total power of the first power 190 and the second power 290 and the functions of the printing device 1A that can be executed with that total power. The supply indicator LED 16 is composed of three LEDs. The three LEDs emit, for example, green light. In FIG. 7, black indicates that the LED is off, a diagonal line sloping downward to the right indicates that the LED is flashing, and white indicates that the LED is lit. In the following description, the right side of the paper is defined as the right side of the supply indicator LED 16, and the left side of the paper is defined as the left side of the supply indicator LED 16.

[0051] The supply indicator LED 16 indicates the total power of the first power 190 and the second power 290 and the functions of the printing device 1A that can be executed with the total power by the number of lit LEDs. When the total power is large enough to execute only the control function of the printing device 1A among the functions of the printing device 1A, only one of the three LEDs, the rightmost LED, lights up.

[0052] When the total power level of the supply indicator LED 16 is sufficient to execute the transport and control functions of the printing device 1A, the two rightmost LEDs of the three LEDs are lit. When the total power level of the supply indicator LED 16 is sufficient to execute the printing, transport, and control functions of the printing device 1A, all three LEDs are lit. Note that when the printing, transport, and control functions of the printing device 1A can be executed, and the printing unit 13 cannot execute normal printing but can execute printing at a slower-than-normal speed, the two rightmost LEDs of the three LEDs are lit and the leftmost LED flashes. The function indicator LED 15 and supply indicator LED 16, which display the functions of the printing device 1A that can be executed using the total power of the first power 190 and the second power 290, are collectively referred to as the display unit 17.

[0053] 2, the control when the printing device 1A is supplying power to the second power source 201 will be described. When the first supply circuit 70 of the printing device 1A supplies the first power 190 and the second power 290 in parallel to the printing unit 13, the printing device 1A opens the switch 87 to stop power supply to the second USB port 12. The printing device 1A then negotiates with the second power source 201 using the second controller 22 and receives power from the second power source 201. As a result, the printing device 1A supplies the first power 190 and the second power 290 in parallel to the printing unit 13, and the printing unit 13 performs printing.

[0054] Furthermore, when the first controller 21 and the first power source 101 renegotiate while power is being supplied to the second power source 201 in the printing device 1A, the switch 87 is opened to stop the power supply to the second USB port 12. After stopping the power supply to the second USB port 12, the first controller 21 starts renegotiation with the first power source 101. Renegotiation occurs, for example, when a device other than the first power source 101 is connected to the USB hub 110 and the connected device receives power from the first power source 101, causing a change to reduce the first power 190. When the first controller 21 and the first power source 101 renegotiate, the power supply from the first power source 101 is momentarily interrupted. The printing device 1A stops the supply of power to the second power source 201, negotiates with the second power source 201 using the second controller 22, and after receiving power from the second power source 201, the first controller 21 and the first power source 101 renegotiate. As a result, the printing device 1A supplies the second power 290 to the functional unit 60 even when the first controller 21 and the first power source 101 renegotiate, thereby preventing momentary interruptions in the power supply to the functional unit 60.

[0055] The main processing executed by the CPU 91 will be described with reference to FIGS. 8 to 11. The main processing mainly involves controlling the supply and receipt of power. The main processing begins when power is supplied to the printing device 1A. More specifically, when the first power source 101 or the second power source 201 is connected to the printing device 1A while both the first power source 101 and the second power source 201 are not connected, the first power 190 or the second power 290 is supplied to the control board 99 via the power line 75. At this time, the first controller 21 or the second controller 22 negotiates with the corresponding one of the first power source 101 or the second power source 201, without being controlled by the CPU 91. When power is supplied to the control board 99, the CPU 91 reads a control program for executing the main processing from the ROM 92. This causes the CPU 91 to start the main processing. As shown in FIG. 8, when the main processing begins, the CPU 91 executes the power supply processing shown in FIG. 12 (S1).

[0056] The power supply process executed in the main process will be described with reference to Figure 12. In the power supply process, the amount of power to be received by the printing device 1A is determined. When the power supply process starts, the CPU 91 determines whether the number of power sources connected to the printing device 1A is one (S61).

[0057] When the CPU 91 determines that the number of connected power sources is one (S61: YES), it determines whether the first USB port 11 is connected to the first power source 101 (S62). When the CPU 91 determines that the first USB port 11 is connected to the first power source 101 (S62: YES), it causes the first controller 21 to execute negotiation with the first power source 101 (S63). The CPU 91 outputs a signal notifying the adjustment circuit 30 of the magnitude of the voltage of the first power 190 determined by the negotiation (S64). Based on the received signal, the adjustment circuit 30 adjusts the magnitude of the voltage of the first power 190 on the power line 41 using the first transformer unit 31A. The CPU 91 then returns the processing to the main processing.

[0058] When the CPU 91 determines that the first USB port 11 is not connected to the first power source 101 (S62: NO), it determines that the second USB port 12 is connected to the second power source 201, and causes the second controller 22 to execute negotiation with the second power source 201 (S65). The CPU 91 outputs a signal notifying the adjustment circuit 30 of the magnitude of the voltage of the second power 290 determined by the negotiation (S66). Based on the received signal, the adjustment circuit 30 adjusts the magnitude of the voltage of the second power 290 on the power line 42 using the second transformer unit 32A. The CPU 91 then returns the processing to the main processing.

[0059] When the CPU 91 determines that the number of connected power sources is not one (S61: NO), it determines that the first USB port 11 is connected to the first power source 101 and the second USB port 12 is connected to the second power source 201, and executes negotiation (S67). In the negotiation of S67, the CPU 91 causes the first controller 21 to execute negotiation with the first power source 101, and causes the second controller 22 to execute negotiation with the second power source 201. The CPU 91 executes negotiation so that the voltage of the first power 190 and the voltage of the second power 290 are the same magnitude. The CPU 91 outputs a signal to notify the adjustment circuit 30 of the magnitude of the voltage determined by the negotiation (S68). Based on the received signal, the adjustment circuit 30 adjusts the voltage of the first power 190 on the power line 41 and the voltage of the second power 290 on the power line 42 using the first transformer unit 31A and the second transformer unit 32A so that they are the same magnitude. The CPU 91 returns the processing to the main processing.

[0060] 8, after the CPU 91 executes a power supply process (S1), it closes the switches 85 and 86 to supply power to the system unit 90 and starts display by the system unit 90 (S2). Either the first power source 101 or the second power source 201 is connected to the printing device 1A.

[0061] The CPU 91 checks the amount of power supplied from the power source (S3). The CPU 91 determines whether all functions of the printing device 1A can be executed with the checked power (S4). If the CPU 91 determines that all functions can be executed with the checked power (S4: YES), the process proceeds to S9.

[0062] If the CPU 91 determines that all functions cannot be executed with the confirmed power (S4: NO), it determines whether a function to be executed can be selected from multiple functions with the confirmed power (S5). If the CPU 91 determines that a function to be executed cannot be selected from multiple functions with the confirmed power (S5: NO), it determines that only control by the system unit 90 can be executed, and causes the liquid crystal display 19 to display a screen prompting connection to a power source that can supply more power (S6). The CPU 91 proceeds to S12 shown in FIG. 9.

[0063] If the CPU 91 determines that a function to be executed can be selected from multiple functions with the confirmed power (S5: YES), it causes the LCD display 19 to display the functions that can be executed by the function unit 60 (S7). The user checks the functions displayed on the LCD display 19 and uses the operation unit 18 to select a function to be executed by the function unit 60. The operation unit 18 accepts the user's selection operation and outputs it to the CPU 91. The CPU 91 determines whether the user's selection is complete (S8). If the CPU 91 determines that the user's selection is not complete (S8: NO), the process returns to S8.

[0064] If the CPU 91 determines that the user's selection is complete (S8: YES), it receives the power determined by the negotiation from the power source (S9). The functional unit 60 is supplied with power from either the first power source 101 or the second power source 201, whichever is connected to the printing device 1A. The CPU 91 determines whether or not to execute renegotiation (S10). If the CPU 91 determines not to execute renegotiation (S10: NO), it executes execution return processing (S11). The execution return processing is processing that restores the function executed by the functional unit 60 when the power supply from the power source is changed. The execution return processing will be described in detail later. The CPU 91 proceeds to S12 shown in FIG. 9.

[0065] 9, the CPU 91 determines whether or not to execute printing using the printing unit 13 (S12). If the CPU 91 determines not to execute printing using the printing unit 13 (S12: NO), the process proceeds to S18. If the CPU 91 determines to execute printing using the printing unit 13 (S12: YES), the CPU 91 determines whether or not power is being supplied to the second power source 201 (S15). If the CPU 91 determines that power is being supplied to the second power source 201 (S15: YES), the CPU 91 opens the switch 87 to stop the supply of power to the second power source 201 (S17). The CPU 91 proceeds to S21.

[0066] If the CPU 91 determines that power is not being supplied to the second power source 201 (S15: NO), the printing unit 13 prints on the medium (S16), and the process proceeds to S18. The CPU 91 determines whether the first power source 101 or the second power source 201 has been additionally connected (S18). If the CPU 91 determines that the first power source 101 or the second power source 201 has not been additionally connected (S18: NO), the process returns to S3 shown in FIG. 8. If the CPU 91 determines that the first power source 101 or the second power source 201 has been additionally connected (S18: YES), the CPU 91 executes a power supply process (S21). The power supply process of S21 is the same as the power supply process of S1. Both the first power source 101 and the second power source 201 are connected to the printing device 1A. The CPU 91 proceeds to S22 shown in FIG. 10.

[0067] 10, the CPU 91 checks the magnitude of the first power 190 and the second power 290 supplied from the first power source 101 and the second power source 201 (S22). The CPU 91 determines whether all functions of the printing device 1A can be executed with the total power of the first power 190 and the second power 290 checked in S22 (S23). If the CPU 91 determines that all functions can be executed with the total power (S23: YES), the process proceeds to S28.

[0068] If the CPU 91 determines that all functions cannot be executed with the total power (S23: NO), it determines whether a function to be executed can be selected from multiple functions with the total power (S24). If the CPU 91 determines that a function to be executed cannot be selected from multiple functions with the total power (S24: NO), it determines that only control by the system unit 90 can be executed, and causes the liquid crystal display 19 to display a screen prompting connection to a power source that can supply more power (S25). The CPU 91 proceeds to S31.

[0069] If the CPU 91 determines that a function to be executed can be selected from multiple functions with the total power consumption (S24: YES), it causes the LCD display 19 to display the functions that can be executed by the function unit 60 (S26). The user checks the functions displayed on the LCD display 19 and uses the operation unit 18 to select a function to be executed by the function unit 60. The operation unit 18 accepts the user's selection operation and outputs it to the CPU 91. The CPU 91 determines whether the user's selection is complete (S27). If the CPU 91 determines that the user's selection is not complete (S27: NO), the process returns to S27.

[0070] If the CPU 91 determines that the user's selection is complete (S27: YES), the power determined by the negotiation is received from the first power source 101 and the second power source 201 (S28). The first power 190 and the second power 290 are supplied in parallel to the functional unit 60. The CPU 91 determines whether or not to execute renegotiation (S29). If the CPU 91 determines not to execute renegotiation (S29: NO), it executes execution return processing (S30) and proceeds to S31.

[0071] The CPU 91 determines (S31) whether or not to supply power to the second power supply 201. If the CPU 91 determines to supply power to the second power supply 201 (S31: YES), it closes the switch 87 to supply power to the second power supply 201 (S32). The CPU 91 returns the process to S3 shown in FIG.

[0072] If the CPU 91 determines that power is not to be supplied to the second power source 201 (S31: NO), it determines whether the connection of the first power source 101 or the second power source 201 has been disconnected (S33). If the CPU 91 determines that the connection of the first power source 101 or the second power source 201 has not been disconnected (S33: NO), it returns the process to S22.

[0073] When the CPU 91 determines that the first power source 101 or the second power source 201 has been disconnected (S33: YES), it stops the execution of some functions of the functional unit 60 other than the control board 99 and the system unit 90 (S34). The CPU 91 executes a power supply process (S35) and returns the process to S3 shown in FIG.

[0074] 11, when the CPU 91 determines to execute renegotiation (S10: YES, S29: YES), it determines whether the number of connected power sources is one (S41). When the CPU 91 determines that the number of connected power sources is not one (S41: NO), it determines whether all functions of the printing device 1A can be executed using only either the first power 190 or the second power 290, assuming that both the first power source 101 and the second power source 201 are connected to the printing device 1A (S42).

[0075] If the CPU 91 determines that all functions of the printing device 1A can be executed using only either the first power 190 or the second power 290 (S42: YES), the process proceeds to S45. If the CPU 91 determines that all functions of the printing device 1A cannot be executed using only either the first power 190 or the second power 290 (S42: NO), the process proceeds to S43 to determine whether some functions of the printing device 1A other than the control board 99 and system unit 90 are currently being executed. If the CPU 91 determines that some functions of the printing device 1A other than the control board 99 and system unit 90 are not currently being executed (S43: NO), the process proceeds to S45. If the CPU 91 determines that some functions of the printing device 1A other than the control board 99 and system unit 90 are currently being executed (S43: YES), the CPU 91 opens switches 81-84 to stop the functions of the functional units 60 other than the control board 99 and system unit 90 (S44), and the process proceeds to S45.

[0076] The CPU 91 determines whether or not power is being supplied from the printing device 1A to the second power source 201 (S45). If the CPU 91 determines that power is not being supplied from the printing device 1A to the second power source 201 (S45: NO), the process proceeds to S48. If the CPU 91 determines that power is being supplied from the printing device 1A to the second power source 201 (S45: YES), the CPU 91 opens the switch 87 to stop the supply of power to the second power source 201 (S46). The CPU 91 negotiates with the second power source 201 using the second controller 22, receives power from the second power source 201 (S47), and proceeds to S48.

[0077] The CPU 91 renegotiates with the power source for which renegotiation has been requested by the first controller 21 or the second controller 22 (S48). The CPU 91 outputs a signal notifying the adjustment circuit 30 of the magnitude of the voltage determined by the renegotiation (S49). Based on the received signal, the adjustment circuit 30 adjusts the magnitude of the voltage of the first power 190 on the power line 41 using the first transformer unit 31A, and adjusts the magnitude of the voltage of the second power 290 on the power line 42 using the second transformer unit 32A. The CPU 91 resumes the function stopped in S44 (S50). The processing of S50 is omitted if the processing of S44 is not being executed. The CPU 91 resumes the supply of power to the second power source 201 that was stopped in S46 (S51). The processing of S51 is omitted if the processing of S46 is not being executed. The CPU 91 returns the processing to S22 shown in FIG. 10.

[0078] If the CPU 91 determines that the number of connected power sources is one (S41: YES), it determines that either the first power source 101 or the second power source 201 is connected to the printing device 1A, and transitions the printing device 1A to a sleep state (S52). In the sleep state, the supply of power to components other than the CPU 91, ROM 92, RAM 93, storage device 94, first controller 21, and second controller 22 is stopped.

[0079] The CPU 91 renegotiates with either the first power source 101 or the second power source 201 connected to the printing device 1A (S53). The CPU 91 cancels the sleep state entered in S52 (S54). The CPU 91 outputs a signal notifying the adjustment circuit 30 of the voltage magnitude determined by the renegotiation (S55). The CPU 91 returns the process to S3 shown in FIG. 8.

[0080] The execution return process executed in the main process will be described with reference to Fig. 13. When the execution return process starts, the CPU 91 determines whether or not execution of the function is stopped by the process of S34 shown in Fig. 10 (S71). If the CPU 91 determines that execution of the function is stopped (S71: YES), the process proceeds to S73.

[0081] When the CPU 91 determines that the execution of the function is not stopped (S71: NO), it determines whether the power supplied from the power supply has been reduced as a result of the renegotiation (S72).When the CPU 91 determines that the power supplied from the power supply has not been reduced (S72: NO), it executes the function by the functional unit 60 (S74) and returns the processing to the main processing.

[0082] When the CPU 91 determines that the execution of a function is stopped (S71: YES), or when it determines that the power supplied from the power source has decreased (S72: YES), it determines whether or not a function has been selected from multiple functions (S73). When the CPU 91 determines that a function has been selected in the processing of S8 or S27 (S73: YES), it executes the function of the selected function unit 60 (S75) and returns the processing to the main processing. When the CPU 91 determines that a function has not been selected (S73: NO), it causes the liquid crystal display 19 to display a cancellation message informing that the execution of the function by the function unit 60 other than the control board 99 and the system unit 90 has been canceled (S76), and returns the processing to the main processing.

[0083] As described above, the printing device 1A has a first USB port 11, a second USB port 12, a functional unit 60, a first supply circuit 70, and a voltage difference adjustment unit 40A. The first USB port 11 receives first power 190 from a first power source 101. The second USB port 12 receives second power 290 from a second power source 201. The functional unit 60 executes the functions of the printing device 1A. The first supply circuit 70 connects the first USB port 11 and the second USB port 12 in parallel to the functional unit 60. The voltage difference adjustment unit 40A adjusts the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. As a result, the first power 190 and the second power 290 are supplied in parallel to the functional unit 60. When the first supply circuit 70 supplies the first power 190 and the second power 290 in parallel to the functional unit 60, a voltage difference between the voltage of the first power 190 and the voltage of the second power 290 may occur in the first supply circuit 70. This voltage difference may occur, for example, when the connection to either the first power source 101 or the second power source 201 is momentarily interrupted. In the printing device 1A, the voltage difference adjustment unit 40A adjusts the voltage difference in the first supply circuit 70, so that the first power 190 or the second power 290 does not flow back through the first supply circuit 70. Therefore, the printing device 1A can supply the first power 190 and the second power 290 in parallel to the functional unit 60. Therefore, even if the connection to either the first power source 101 or the second power source 201 is momentarily interrupted, the functions of the printing device 1A can be stably executed using the power received from the other of the first power source 101 or the second power source 201.

[0084] The first USB port 11 is connected to the first power source 101 via a connection conforming to the USB standard. The second USB port 12 is connected to the second power source 201 via a connection conforming to the USB standard. This allows the voltage of the first power 190 and the voltage of the second power 290 to be adjusted even when the printing device 1A is configured to receive the first power 190 and the second power 290 via a connection conforming to the USB standard. Because the first power 190 or the second power 290 does not flow back in the first supply circuit 70, the printing device 1A can stably perform its functions.

[0085] The printing device 1A further includes a first transformer unit 31A and a second transformer unit 32A. The voltage difference adjustment unit 40A includes an adjustment circuit 30. The adjustment circuit 30 transforms the magnitude of the voltage of the first power 190 on the power line 41 using the first transformer unit 31A, and transforms the magnitude of the voltage of the second power 290 on the power line 42 using the second transformer unit 32A. As a result, the adjustment circuit 30 transforms the voltage of the first power 190 using the first transformer unit 31A, and transforms the voltage of the second power 290 using the second transformer unit 32A. Therefore, even if there is a voltage difference between the voltages of the first power 190 and the second power 290, the printing device 1A adjusts the voltage difference, and the first power 190 and the second power 290 are stably supplied in parallel to the functional unit 60.

[0086] In the printing device 1A, the first USB port 11 is connected to the first power source 101 via a connection conforming to the USBPD standard. The second USB port 12 is connected to the second power source 201 via a connection conforming to the USBPD standard. The voltage difference adjustment unit 40A includes a first controller 21, a second controller 22, and a CPU 91. The first controller 21 negotiates with the first power source 101. The second controller 22 negotiates with the second power source 201. The CPU 91 causes the first controller 21 and the second controller 22 to negotiate based on the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. Accordingly, when there is a voltage difference between the voltage of the first power 190 and the voltage of the second power 290, the CPU 91 causes the first controller 21 and the second controller 22 to negotiate. Therefore, even when there is a voltage difference between the voltage of the first power 190 and the voltage of the second power 290, the printing device 1A adjusts the voltage difference, and the first power 190 and the second power 290 are stably supplied in parallel to the functional unit 60.

[0087] Printing device 1A further has a second supply circuit 49 that supplies first power 190 received from first USB port 11 to second USB port 12. Accordingly, second supply circuit 49 supplies first power 190 to second USB port 12. Since second USB port 12 is connected to second power source 201 in accordance with the USBPD standard, printing device 1A can supply power to second power source 201 by receiving power in accordance with the USBPD standard.

[0088] In the printing device 1A, the functional unit 60 includes the printing unit 13. The printing unit 13 prints on a medium. The second supply circuit 49 includes a switch 87 that switches between supplying and stopping the first power 190 to the second USB port 12. When the first supply circuit 70 supplies the first power 190 and the second power 290 in parallel to the printing unit 13, the switch 87 stops the power supply to the second USB port 12. This means that printing on a medium by the printing unit 13 consumes a large amount of power among the functions executed by the printing device 1A. When the first supply circuit 70 supplies the first power 190 and the second power 290 in parallel to the printing unit 13 for printing on a medium, the switch 87 stops the power supply to the second USB port 12, thereby stopping the power supply to the second power source 201. Because the second power 290 is supplied to the printing unit 13 in parallel with the first power 190, the printing device 1A can stably print using the printing unit 13.

[0089] In the printing device 1A, when the first controller 21 and the first power source 101 renegotiate, the switch 87 stops the power supply to the second USB port 12. After stopping the power supply to the second USB port 12, the first controller 21 starts renegotiation with the first power source 101. According to this, when a negotiation request is received from the first power source 101 while power is being supplied to the second power source 201, the power supply to the second power source 201 is stopped, so that the first power 190 and the second power 290 are supplied in parallel to the functional unit 60. In this state, the first controller 21 negotiates with the first power source 101, so that at least the second power 290 is supplied to the functional unit 60. Therefore, the printing device 1A can prevent a shortage of power supply to the functional unit 60 even when a negotiation request is received from the first power source 101 while power is being supplied to the second power source 201.

[0090] Printing device 1A has a display unit 17. Display unit 17 displays the functions of printing device 1A that can be executed using the total power of first power 190 and second power 290. By checking display unit 17, the user can confirm which of the multiple functions of printing device 1A can be executed using the total power of first power 190 and second power 290.

[0091] In the printing device 1A, the display unit 17 includes a supply indicator LED 16. The supply indicator LED 16 is composed of three LEDs. The three LEDs emit, for example, green light. The supply indicator LED 16 displays the functions of the printing device 1A that can be executed using the total power of the first power 190 and the second power 290, based on the number of lit LEDs. This allows the user to easily check which of the multiple functions of the printing device 1A can be executed using the total power of the first power 190 and the second power 290, by checking the number of lit LEDs.

[0092] In the printing device 1A, the display unit 17 includes a function display LED 15. The function display LED 15 displays the functions of the printing device 1A that can be executed with the total power of the first power 190 and the second power 290, by the colors emitted by the LEDs 151, 152, and 153. This allows the user to easily check which of the multiple functions can be executed with the total power of the received first power 190 and the second power 290, by checking the colors emitted by the LEDs 151, 152, and 153.

[0093] The printing device 1A has an operation unit 18. The operation unit 18 accepts a user's selection operation of a function to be executed by the function unit 60. By performing a selection operation on the operation unit 18 by the user, the printing device 1A can execute the function desired by the user from among a plurality of functions.

[0094] The printing device 1A does not have a battery that stores the received power and supplies the stored power to the functional unit 60. As a result, the printing device 1A supplies the first power 190 and the second power 290 in parallel to the functional unit 60. Even if the connection to one of the first power source 101 or the second power source 201 is momentarily interrupted, the printing device 1A can supply the power received from the other of the first power source 101 or the second power source 201 to the functional unit 60, eliminating the need to supply power to the functional unit 60 from a battery. Therefore, the printing device 1A can prevent the housing 2 from becoming larger by installing a battery.

[0095] <Modification> The present invention can be modified in various ways from the above-described embodiment. It goes without saying that the various modifications described below can be combined with each other as long as no contradictions arise, and can also be applied to other embodiments as appropriate as long as no contradictions arise.

[0096] In the above embodiment, the user uses the operation unit 18 to select from multiple functions of the printing device 1A, and the function unit 60 executes the selected function. Alternatively, the CPU 91 may select from multiple functions of the printing device 1A and execute them based on the total power of the first power 190 and the second power 290. In this case, the CPU 91 controls the execution of functions based on the total power of the first power 190 and the second power 290, allowing the printing device 1A to execute functions according to the total power of the first power 190 and the second power 290 without any effort on the part of the user. In this case, steps S7, S8, S26, and S27 may be omitted from the main processing. The printing device 1A does not need to have an operation unit 18.

[0097] The first USB port 11 may be connected to the first power source 101 via a connection conforming to the USB standard, and does not have to be connected to the first power source 101 via a connection conforming to the USBPD standard. The first USB port 11 may also be connected to the first power source 101 via another standard that allows the first controller 21 to determine the first power 190 through negotiation with the first power source 101. The number and configuration of the first power sources 101 may be changed as appropriate.

[0098] The second USB port 12 may be connected to the second power source 201 via a connection conforming to the USB standard, and does not have to be connected to the second power source 201 via a connection conforming to the USBPD standard. The second USB port 12 may be connected to the second power source 201 via another standard that allows the second controller 22 to determine the second power 290 through negotiation with the second power source 201. The number and configuration of the second power sources 201 may be changed as appropriate.

[0099] The first supply circuit 70 may have any configuration as long as it connects the first USB port 11 and the second USB port 12 in parallel to the functional unit 60. The first supply circuit 70 does not have to include the switches 81-86, for example.

[0100] The printing device 1A may not have the first transformer unit 31A. The first transformer unit 31A may be a unit that increases the voltage of the first power 190 and does not decrease the voltage of the first power 190. The printing device 1A may not have the second transformer unit 32A. The second transformer unit 32A may be a unit that increases the voltage of the second power 290 and does not decrease the voltage of the second power 290.

[0101] The voltage difference adjustment unit 40A does not need to include the adjustment circuit 30. The configuration of the adjustment circuit 30 may be changed as appropriate. The adjustment circuit 30 may not need to transform the voltage of the first power 190 using the first transformer unit 31A and transform the voltage of the second power 290 using the second transformer unit 32A. The adjustment circuit 30 may transform the voltage of the second power 290 using the second transformer unit 32A and not transform the voltage of the first power 190 using the first transformer unit 31A. The adjustment circuit 30 may not need to communicate with the CPU 91. In other words, the adjustment circuit 30 may transform the voltage of the first power 190 using the first transformer unit 31A and transform the voltage of the second power 290 using the second transformer unit 32A, without being controlled by the CPU 91.

[0102] The voltage difference adjusting unit 40A may not include the first controller 21. In this case, the second controller 22 may negotiate not only with the second power source 201 but also with the first power source 101. The voltage difference adjusting unit 40A can adjust the voltage difference between the voltage of the first power 190 and the voltage of the second power 290 by negotiating between the first power source 101 and the second power source 201 using the second controller 22. The voltage difference adjusting unit 40A may not include the second controller 22. In this case, the voltage difference adjusting unit 40A may negotiate not only with the first power source 101 but also with the second power source 201 using the first controller 21. The voltage difference adjusting unit 40A can adjust the voltage difference between the voltage of the first power 190 and the voltage of the second power 290 by negotiating between the first power source 101 and the second power source 201 using the first controller 21. The CPU 91 may not have to cause the first controller 21 to negotiate with the first power source 101 based on the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. The CPU 91 may not have to cause the second controller 22 to negotiate with the second power source 201 based on the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. The CPU 91 may cause the first controller 21 to negotiate, but not have the second controller 22 negotiate. The CPU 91 may cause the second controller 22 to negotiate, but not have the first controller 21 negotiate. The voltage difference adjusting unit 40A may cause the first controller 21 and the second controller 22 to negotiate, without being based on the control of the CPU 91.

[0103] The printing device 1A does not need to have the second supply circuit 49. The configuration of the second supply circuit 49 may be changed as appropriate. The second supply circuit 49 may supply the second power 290 to the first USB port 11. The second supply circuit 49 may not include the switch 87. The printing device 1A does not need to stop the supply of power to the second power source 201 when printing is performed by the printing unit 13. The printing device 1A does not need to stop the supply of power to the second power source 201 when a renegotiation request is received from the first power source 101.

[0104] In the printing device 1A, the display mode of the display unit 17 may be changed as appropriate. The display unit 17 may include, for example, a liquid crystal display 19. In this case, the display unit 17 may display the functions of the printing device 1A that can be executed based on the total power of the first power 190 and the second power 290 using an image displayed on the liquid crystal display 19. The display unit 17 may not include the supply indicator LED 16. The number of LEDs that the supply indicator LED 16 emits may not be changed based on the executable functions of the printing device 1A. The number of LEDs in the supply indicator LED 16 may be changed as appropriate. The display unit 17 may not include the function indicator LED 15. The colors that the LEDs 151, 152, and 153 emit may not be changed based on the executable functions of the printing device 1A. The LEDs 151, 152, and 153 may be configured as multiple single-color LEDs integrated together and are not limited to full-color LEDs. The colors that the LEDs 151, 152, and 153 emit may be changed as appropriate.

[0105] The printing device 1A may have a DC connector for receiving power via a connection that does not conform to the USB standard. The printing device 1A may also have a battery that stores the received power and supplies the stored power to the functional unit 60.

[0106] The configuration of the printing device 1A may be changed as appropriate. For example, the printing device 1A may not have the transport unit 14. The configuration of the functional unit 60 may be changed as appropriate. For example, the functional unit 60 may include a cutter that is driven by electricity and cuts the medium.

[0107] As shown in FIG. 14, the configuration for receiving the first power 190, the configuration for transforming the voltage of the first power 190, the configuration for receiving the second power 290, and the configuration for transforming the voltage of the second power 290 may be changed as appropriate.

[0108] Second Embodiment A printing device 1B of the second embodiment will be described with reference to Figures 15 and 16. The printing device 1B differs from the printing device 1A in that it receives first power 190 via an inlet 132 (described later) and transforms the voltage of the first power 190 in a first transformer unit 31B.

[0109] The printing device 1B includes an outlet 122, a power cable (not shown), an inlet 132, and a voltage difference adjustment unit 40B. The outlet 122 is located outside the housing 2. The outlet 122 can be connected to a first power source 102. The first power source 102 is, for example, a commercial power source, an AC output generator, an AC inverter, or the like, and outputs a first power 190. In the second embodiment, the first power 190 is AC power.

[0110] One end of the power cable is connected to the outlet 122. The other end of the power cable is connected to the inlet 132. The power cable supplies the first power 190 output from the first power source 102 to the inlet 132.

[0111] The inlet 132 is disposed inside the housing 2. The inlet 132 receives the first power 190 and supplies it to the first transformer unit 31B.

[0112] The first transformer unit 31B is disposed in place of the first transformer unit 31A and is, for example, an AC-DC converter. One end of the first transformer unit 31B is connected to the inlet 132. The other end of the first transformer unit 31B is connected to the power line 41.

[0113] The voltage difference adjusting unit 40B includes a CPU 91, a second controller 22, and an adjusting circuit 30. Based on the control of the CPU 91, the adjusting circuit 30 transforms the voltage of the first power 190 using a first transforming unit 31B, and transforms the voltage of the second power 290 using a second transforming unit 32A.

[0114] In the printing device 1B of the second embodiment, the inlet 132 receives the first power 190 from the first power source 102. The first supply circuit 70 connects the inlet 132 and the second USB port 12 in parallel to the functional unit 60. The voltage difference adjustment unit 40B adjusts the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. Therefore, the printing device 1B achieves the same effects as the printing device 1A.

[0115] <Third embodiment> A printing device 1C of the third embodiment will be described with reference to Figures 15 and 17. The printing device 1C differs from the printing device 1B in that it does not have a second supply circuit 49. The printing device 1C is equipped with a voltage difference adjustment unit 40C. Like the voltage difference adjustment unit 40B, the voltage difference adjustment unit 40C includes a CPU 91, a second controller 22, and an adjustment circuit 30.

[0116] Since the printing device 1C does not have the second supply circuit 49, the second power source 201 is a constant source for the printing device 1C, and the printing device 1C is a constant sink for the second power source 201. The printing device 1C has the same effects as the printing device 1A.

[0117] <Fourth embodiment> A printing device 1D of the fourth embodiment will be described with reference to Figures 18 and 19. The printing device 1D differs from the printing device 1C in that it receives second power 290 via an inlet 232 (described later) and transforms the voltage of the second power 290 in a second transformer unit 32B.

[0118] The printing device 1D includes an outlet 222, a power cable (not shown), an inlet 232, and a voltage difference adjustment unit 40D. The outlet 222 is located outside the housing 2. The outlet 222 can be connected to a second power source 202. The second power source 202 is, for example, a commercial power source, an AC output generator, an AC inverter, or the like, and outputs second power 290. In the fourth embodiment, the second power 290 is AC power.

[0119] One end of the power cable is connected to the outlet 222. The other end of the power cable is connected to the inlet 232. The power cable supplies the second power 290 output from the second power source 202 to the inlet 232.

[0120] The inlet 232 is disposed inside the housing 2. The inlet 232 receives the second power 290 and supplies it to the second transformer unit 32B.

[0121] The second transformer unit 32B is disposed in place of the second transformer unit 32A and is, for example, an AC-DC converter. One end of the second transformer unit 32B is connected to the inlet 232. The other end of the second transformer unit 32B is connected to the power line 42.

[0122] The voltage difference adjusting unit 40D includes a CPU 91 and an adjusting circuit 30. Based on the control of the CPU 91, the adjusting circuit 30 transforms the voltage of the first power 190 using a first transforming unit 31B and transforms the voltage of the second power 290 using a second transforming unit 32B.

[0123] In the printing device 1D of the fourth embodiment, the inlet 232 receives the second power 290 from the second power source 202. The first supply circuit 70 connects the inlet 132 and the inlet 232 in parallel to the functional unit 60. The voltage difference adjustment unit 40D adjusts the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. Therefore, the printing device 1D achieves the same effects as the printing device 1A.

[0124] Fifth Embodiment A printing device 1E of the fifth embodiment will be described with reference to Figures 20 and 21. The printing device 1E differs from the printing device 1B in that the second power 290 is received by a battery connector 243 (described later) and the voltage of the second power 290 is transformed by a second transformer 32C.

[0125] The printing device 1E includes a battery connector 243, a detection circuit 253, and a voltage difference adjustment unit 40E. The battery connector 243 is disposed inside the housing 2. The battery connector 243 can be connected to the second power source 203 via a power cable (not shown).

[0126] The second power source 203 is, for example, a DC battery, a DC power source, a DC converter, or the like, and is capable of outputting the second power 290. The second power source 203 is configured to be chargeable and dischargeable. In the fifth embodiment, the second power 290 is DC power. When receiving power from the second power source 203, the battery connector 243 receives the second power 290 from the second power source 203. When charging the second power source 203, the battery connector 243 supplies power to the second power source 203.

[0127] The detection circuit 253 detects the magnitude of the current of the second power 290 received by the battery connector 243 and outputs a signal indicating the magnitude of the current of the second power 290 to the CPU 91 .

[0128] The second transformer unit 32C is disposed in place of the second transformer unit 32A and is, for example, a DC-DC converter. One end of the second transformer unit 32C is connected to the battery connector 243. The other end of the second transformer unit 32C is connected to the power line 42.

[0129] The voltage difference adjusting unit 40E includes a CPU 91 and an adjusting circuit 30. Under the control of the CPU 91, the adjusting circuit 30 transforms the voltage of the first power 190 using a first transforming unit 31B and transforms the voltage of the second power 290 using a second transforming unit 32C.

[0130] The CPU 91 determines whether the magnitude of the current of the second power 290 received by the battery connector 243 is smaller than a threshold value based on the signal output from the detection circuit 253. If the magnitude of the current of the second power 290 is smaller than the threshold value, the CPU 91 closes the switch 87 to supply the first power 190 to the battery connector 243 via the second supply circuit 49. The second power source 203 is charged by the power output from the battery connector 243.

[0131] In the printing device 1E of the fifth embodiment, the battery connector 243 receives the second power 290 from the second power source 203. The first supply circuit 70 connects the inlet 132 and the battery connector 243 in parallel to the functional unit 60. The voltage difference adjustment unit 40E adjusts the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. Therefore, the printing device 1E achieves the same effects as the printing device 1A.

[0132] Sixth Embodiment A printing device 1F of the sixth embodiment will be described with reference to Figures 22 and 23. The printing device 1F differs from the printing device 1E in that it receives first power 190 via a battery connector 143 (described later) and transforms the voltage of second power 290 in a first transformer 31C.

[0133] The printing device 1F includes a battery connector 143 and a voltage difference adjustment unit 40F. The battery connector 143 is disposed inside the housing 2. The battery connector 143 can be connected to the first power source 103 via a power cable (not shown).

[0134] The first power source 103 is, for example, a DC battery, a DC power source, a DC converter, or the like, and is capable of outputting the first power 190. In the sixth embodiment, the first power 190 is DC power. The battery connector 143 receives the first power 190 from the first power source 103.

[0135] The first transformer unit 31C is disposed in place of the first transformer unit 31B and is, for example, a DC-DC converter. One end of the first transformer unit 31C is connected to the battery connector 143. The other end of the first transformer unit 31C is connected to the power line 41.

[0136] The voltage difference adjusting unit 40F includes a CPU 91 and an adjusting circuit 30. Based on the control of the CPU 91, the adjusting circuit 30 transforms the voltage of the first power 190 using a first transforming unit 31C and transforms the voltage of the second power 290 using a second transforming unit 32C.

[0137] In the printing device 1F of the sixth embodiment, the battery connector 143 receives the first power 190 from the first power source 103. The first supply circuit 70 connects the battery connector 143 and the battery connector 243 in parallel to the functional unit 60. The voltage difference adjustment unit 40F adjusts the voltage difference between the voltage of the first power 190 and the voltage of the second power 290. Therefore, the printing device 1F achieves the same effects as the printing device 1A. Note that the printing devices 1E and 1F do not necessarily have the second supply circuit 49. The printing device 1F may further have a third supply circuit that supplies the second power 290 to the battery connector 143. In this case, the first power source 103 is configured to be chargeable and dischargeable. When the printing device 1F has the third supply circuit, it may further have a detection circuit that detects the magnitude of the current of the first power 190 received by the battery connector 243.

[0138] <Other> The first USB port 11, inlet 132, and battery connector 143 are examples of the "first power receiving unit" of the present invention. The second USB port 12, inlet 232, and battery connector 243 are examples of the "second power receiving unit" of the present invention. The CPU 91 is an example of the "overall controller" and "function control unit" of the present invention. The switch 87 is an example of the "switching unit" of the present invention. [Explanation of symbols]

[0139] 1A~1F Printing device 11 1st USB port 12 Second USB port 40A~40F Voltage difference adjustment unit 60 Functional Section 70 1st supply circuit 132, 232 Inlets 143, 243 Battery Connector

Claims

1. a first power receiving unit that receives first power from a first power source; a second power receiving unit that receives second power from a second power source; a functional unit that executes the functions of the printing device; a first supply circuit that connects the first power receiving unit and the second power receiving unit in parallel to the functional unit; a voltage difference adjusting unit in the first supply circuit that adjusts a voltage difference between a voltage of the first power and a voltage of the second power; A printing device comprising:

2. the first power receiving unit is a first USB port that receives the first power from the first power source through a connection conforming to a USB (Universal Serial Bus) standard; The second power receiving unit is a second USB port that receives the second power from the second power source through a connection conforming to the USB standard.

2. The printing device according to claim 1, wherein:

3. a first transformer connected to the first USB port and transforming a voltage of the first power; a second transformer connected to the second USB port and transforming a voltage of the second power, The voltage difference adjustment unit an adjusting circuit that performs at least one of transforming the voltage of the first power by the first transforming unit and transforming the voltage of the second power by the second transforming unit based on the voltage difference; 3. The printing device according to claim 2, wherein:

4. the first USB port is connected to the first power source through a connection conforming to the USB PD (Power Delivery) standard; the second USB port is connected to the second power source through a connection conforming to the USBPD standard; The voltage difference adjustment unit a first controller that negotiates a voltage and current combination of the first power with the first power source; a second controller that negotiates a combination of voltage and current of the second power with the second power source; an overall controller that performs at least one of causing the first controller to negotiate with the first power source or causing the second controller to negotiate with the second power source based on the voltage difference.

3. The printing device according to claim 2, wherein:

5. the second USB port is connected to the second power source through a connection conforming to the USB PD (Power Delivery) standard; Further comprising a second supply circuit that supplies the first power received from the first USB port to the second USB port.

3. The printing device according to claim 2, wherein:

6. the functional unit includes a printing unit that prints on a medium; the second supply circuit includes a switching unit that switches between supplying power to the second USB port and stopping the power supply; The switching unit stops power supply to the second USB port when the first supply circuit supplies the first power and the second power in parallel to the printing unit.

6. The printing device according to claim 5,

7. the first USB port is connected to the first power source through a connection conforming to the USBPD standard; a first controller that negotiates a combination of voltage and current of the first power with the first power source; the second supply circuit includes a switching unit that switches between supplying power to the second USB port and stopping the power supply; When a negotiation request is received from the first power source to the first controller, the switching unit stops power supply to the second USB port, and after the switching unit has completed stopping power supply to the second USB port, the first controller starts negotiation with the first power source.

6. The printing device according to claim 5,

8. The power supply device further includes a display unit that displays, from among the plurality of functions, the functions that can be executed according to the sum of the first power and the second power.

2. The printing device according to claim 1, wherein:

9. The display unit includes a plurality of LEDs (Light Emitting Diodes), and the number of LEDs that emit light is changed depending on the executable functions.

9. The printing device according to claim 8, wherein:

10. The display unit includes an LED that can emit light in a plurality of colors, and the color emitted by the LED changes depending on the executable function.

9. The printing device according to claim 8, wherein:

11. Further comprising an operation unit that accepts a selection operation of the function to be executed by the function unit from the functions displayed on the display unit.

9. The printing device according to claim 8, wherein:

12. Further comprising a function control unit that controls execution of the function based on the sum of the first power and the second power.

2. The printing device according to claim 1, wherein:

13. The device does not have a battery that stores the received power and supplies the stored power to the functional unit.

3. The printing device according to claim 2, wherein:

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