JP2006018466A - Electronic apparatus and power supply control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic device capable of detecting an external device connected to a USB interface and performing appropriate power supply control based on the detection result, and a power supply control method thereof.
An electronic device that can be connected to an external device via a USB interface and can supply power to the external device via a bus and can be driven by a battery power source, and is connected via a USB interface. It is determined whether or not the external device is a device compliant with the USB standard, and the power supply to the external device is controlled using a switch for turning on / off the power supply via the bus according to the determination result.
[Selection] Figure 6

Description

  The present invention relates to an electronic device and its power supply control method, and more particularly to an electronic device that can supply power to an external device via a USB interface and can be driven by a battery, such as a portable printer and its power supply control method. It is.

  It is desirable for battery-powered electronic devices to manage the remaining amount of battery by some method. There are the following two methods for detecting the remaining battery level.

  One is a method called an energy integration method, in which the discharge current is integrated and subtracted from the total capacity of the battery. This method has the advantage that the remaining amount can be calculated with high precision, but has the disadvantage that the system for realizing this method becomes complicated and relatively expensive.

  The other is a method called a voltage detection method. Since the battery has a property that the output voltage gradually decreases as the remaining amount decreases, the remaining amount can be estimated from the battery voltage. However, since the battery voltage changes due to individual variations and load fluctuations, there is a drawback that the remaining amount detection accuracy is lowered. Conversely, a system that implements this method is relatively simple and has the advantage that it can be implemented at low cost.

When an electronic device that operates as a host via a conventional USB interface (hereinafter referred to as a USB host function) performs power management of the USB device, it performs enumeration with the USB device, thereby maximizing the power consumption of the USB device. Value data was acquired, and control was performed based on the result (see, for example, Patent Document 1). However, when a USB bus-powered device that does not conform to the USB standard (hereinafter referred to as a bus-powered device) is connected to the USB port, enumeration is not started and Vbus is not started. Only supplied power.
JP 2004-086359 A

  As described above, when a non-standard bus-powered device is connected to an electronic device having a conventional USB host function, the electronic device does not recognize that it is supplying power to Vbus. Therefore, unexpected power will be supplied. In particular, battery-powered electronic devices have a problem that unexpected power consumption accelerates battery consumption and cannot perform its intended function.

  The present invention has been made in view of the above-described conventional example. An electronic device capable of detecting an external device connected to a USB interface and appropriately controlling power supply based on the detection result, and a power supply control method thereof are provided. It is intended to provide.

  In order to achieve the above object, an electronic apparatus of the present invention has the following configuration.

  That is, an electronic device that can be connected to an external device via a USB interface and can be driven by a battery power source, the bus supplying power to the external device connected via the USB interface, and the bus According to a determination result by the determination means, a switch for turning ON / OFF the power supply via the USB, a determination means for determining whether the external device connected via the USB interface is a device compliant with the USB standard, And an electronic device having control means for controlling power supply to the external device using the switch.

  Here, the determining means includes a first measuring means for measuring a battery voltage when power is supplied to the external device via the bus, and a plurality of times measured by the first measuring means. According to the determination result of the first determination means and the first determination means for determining whether there is a voltage drop of a predetermined value or more between the previous measurement result and the current measurement result. A second measuring means for measuring a battery voltage when power supply to the external device via the bus is stopped and no power is supplied, and a battery measured by the first and second measuring means. A second determination means for comparing voltages and determining whether or not the battery voltage when the power supply is not performed is higher than a predetermined value from the battery voltage when the power supply is performed; The second discriminator In accordance with the judgment results of the said connected external device may be determined whether the device complying with the USB standard.

  Further, the determining means has third determining means for determining whether or not the voltage of the specific signal line of the USB interface is pulled up to a predetermined voltage, and according to the determination result by the third determining means, It may be determined whether the connected external device is a device that conforms to the USB standard.

  Furthermore, it is preferable to have battery remaining amount detecting means for detecting the remaining amount of the battery according to a voltage detection method.

  In the present invention, it is preferable that the electronic device is a printer and the external device compliant with the USB standard is a PictBridge compatible device.

  According to another invention, there is provided a power supply control method for an electronic device that can be connected to an external device via a USB interface, can supply power to the external device via a bus, and can be driven by a battery power source. A determination step for determining whether or not an external device connected via the USB interface is a device compliant with the USB standard, and power supply ON / OFF via the bus is determined according to the determination result in the determination step. And a control step of controlling power supply to the external device using a switch to be performed.

  Therefore, according to the present invention, it is determined whether a device conforming to the USB standard is connected to the USB interface, and the power supply to the connected device is controlled according to the result, so that a device not conforming to the USB standard is connected. When this occurs, there is an effect that wasteful power consumption can be suppressed.

  Also, for example, when using a battery-driven electronic device equipped with a USB interface and a mechanism for managing the remaining battery level using the voltage detection method, the connected battery level can be used as it is to determine the connected device. Therefore, it is not necessary to newly provide an extra mechanism for the determination, which is advantageous in terms of cost.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings.

  In this specification, “recording” (sometimes referred to as “printing”) is not only for forming significant information such as characters and figures, but also for human beings visually perceived regardless of significance. Regardless of whether or not it has been manifested, it also represents a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or the medium is processed.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used for forming a pattern or the like, processing a recording medium, or processing an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port or a liquid channel communicating with the ejection port and an element that generates energy used for ink ejection.

  Furthermore, the recording head applicable to the present invention employs an ink jet recording method, and as a specific form thereof, film boiling occurs in the liquid using the thermal energy generated by the electrothermal transducer. Various forms such as a form for generating bubbles to form, a form for discharging liquid by an electromechanical transducer, and a form for forming and discharging liquid droplets using static electricity or air flow can be mentioned. Those using a converter are preferably used.

  FIG. 1 is an external perspective view showing an outline of the overall configuration of an ink jet recording apparatus (hereinafter referred to as a recording apparatus) that can be driven by both an AC power source and a DC power source according to a typical embodiment of the present invention. As shown in FIG. 1, the recording apparatus includes an ink jet printer (hereinafter referred to as a printer) 800, a battery charger 900 with a built-in battery that can be attached to and detached from the main body of the printer 800, and a vertically installed storage with the both attached. The cradle 950 is a cradle. Note that although description will be given by taking paper as an example of a recording medium to be recorded by the printer, the recording medium is not limited to this, and any recordable sheet-like medium may be used.

  In FIG. 1, the external appearance of the printer 800 is an integral shell structure composed of an upper case 801, a lower case 802, a paper feed cover 803, and a paper discharge port cover 804, and is not used as a printer (when stationary, portable) Time) takes this form. Also, on the side surface of the printer 800, an I / F for connecting a DCin jack (DC power supply input jack) 817 for inserting an AC adapter cable (not shown) used when receiving power supply from an AC power supply and a USB cable. An (interface) connector 815 is provided. A paper feed cover 803 serves as a recording sheet supply tray for opening a recording sheet such as paper by being opened with respect to the printer main body during recording.

  Next, the external appearance of the battery charger 900 is composed of a main case 901, a cover case 902, and a battery lid 903. By removing the battery lid 903 and opening the main case 901, the battery pack incorporating the rechargeable battery can be removed. Is possible.

  Further, the mounting surface (connection surface) between the battery charger 900 and the printer 800 has a main body connector 904 for electrical connection and fixing screws 905 and 906 for mechanical attachment and fixing. By connecting to the printer body in the direction of arrow A in FIG. 1, the printer 800 can be driven by a battery. Further, the top surface of the battery charger 900 has a charging display portion 909 that indicates the state of charge of the battery. On the side surface of the battery charger 900, a CHG-DCin jack 907 into which an AC adapter cable is inserted and a battery charger 900 are attached. Sometimes a blindfold plate 908 is provided to cover the DCin jack 817 of the printer 800.

  The cradle 950 functions as a stand by being inserted in the direction of arrow B in FIG. 1 with the battery charger 900 attached to the printer 800. The cradle 950 is provided with an opening 956 so that charging can be performed by inserting an AC adapter cable into the CHG-DCin jack 907 even when the printer 800 and the battery charger 900 are attached.

  FIG. 2 is a perspective view of the state in which the battery charger 900 is mounted on the printer 800 as viewed from the upper side of the printer on the back side and the top side of the printer.

  As shown in FIG. 2, by attaching a battery charger 900 to the back of the printer 800 and fixing it with fixing screws 905 and 906, the printer 800 becomes a battery-driven printer.

  Further, as described above, the DCin jack 817 of the printer 800 is covered by the blindfold plate 908 provided in the battery charger 900. For this reason, when the user attaches the battery charger 900, the AC adapter cable is definitely inserted into the CHG-DCin jack 907 side of the battery charger 900, thereby preventing erroneous insertion.

  On the back surface of the battery charger 900, four legs 901a, 901b, 901c, 901d provided on the main case 901 are provided. In addition, contact portions 910a, 910b, and 910c for making electrical contact when attached to the cradle 950 are provided on the rear surface.

  Further, as shown in FIG. 2, the charging display unit 909 of the battery charger 900 is visible even when the printer 800 is mounted and the top surface is easy to see when used for recording and when the paper feed cover 803 is opened. It is arranged at a position where it is not obstructed.

  FIG. 3 is a perspective view showing the internal configuration of the printer 800.

  As shown in FIG. 3, the recording head 105 is mounted on the carriage 104 and can reciprocate in the longitudinal direction along the guide rail 103. The ink ejected from the recording head 105 reaches the recording medium 102 whose recording surface is regulated by a platen (not shown) at a minute distance from the recording head 105, and forms an image thereon.

  A recording signal is supplied to the recording head 105 according to the image data via the flexible cable 119.

  In FIG. 3, reference numeral 114 denotes a carriage motor for causing the carriage 104 to scan along the guide rail 103. Reference numeral 113 denotes a carriage belt that transmits the driving force of the carriage motor 114 to the carriage 104. A transport motor 118 is coupled to the transport roller 101 to transport the recording medium 102.

  The recording head 105 is combined with the ink tank 105b to form a head cartridge. The head cartridge may have a configuration in which the recording head and the ink tank can be separated, or an integrated configuration.

  FIG. 4 is a block diagram showing a control configuration of the printer 800 shown in FIGS.

  As shown in FIG. 4, the controller 600 includes an MPU 601, a program corresponding to a control sequence to be described later, a required table, a ROM 602 storing other fixed data, control of the carriage motor 114, control of the transport motor 118, and recording. A special purpose integrated circuit (ASIC) 603 that generates a control signal for controlling the head 3, and a RAM 604, an MPU 601, an ASIC 603, and a RAM 604, which are provided with image data development areas and program execution areas A system bus 605 for transferring data, and an A / D converter 606 for inputting analog signals from the sensor group described below, A / D converting them, and supplying digital signals to the MPU 601 and the like.

  In FIG. 4, reference numeral 610 denotes a computer (or a reader for image reading, a digital camera, etc.) serving as a supply source of image data, and is collectively referred to as a host device. Image data, commands, status signals, and the like are transmitted and received between the host apparatus 610 and the recording apparatus 1 via an interface (I / F) 611. In this embodiment, the interface 611 is an interface conforming to the USB standard.

  Further, reference numeral 620 denotes a switch group, which instructs activation of a power switch 621, a print switch 622 for instructing printing start, and a process (recovery process) for maintaining the ink ejection performance of the recording head 105 in a good state. For example, a recovery switch 623 for receiving a command input from the operator. Reference numeral 630 denotes a sensor for detecting an apparatus state including a position sensor 631 such as a photocoupler for detecting a home position, a temperature sensor 632 provided at an appropriate position of the recording apparatus for detecting an environmental temperature, and the like. Is a group.

  Further, reference numeral 640 denotes a carriage motor driver that drives a carriage motor 114 for reciprocating scanning of the carriage 104 along the guide rail 103, and reference numeral 642 denotes a conveyance motor driver that drives a conveyance motor 118 for conveying the recording medium 102.

  The ASIC 603 transfers printing element (ejection heater) drive data (DATA) to the print head while directly accessing the storage area of the RAM 602 during print scan by the print head 105.

  A head temperature sensor 105 a for measuring the head temperature is provided inside the recording head 105.

  In addition, the printer 800 is a small battery (lithium battery, nickel-metal hydride battery, alkaline button battery, silver oxide battery, zinc-air battery) so that the timekeeping operation can be continued even when the power supply from the AC power supply or DC power supply is lost. A timer 607 operable with power supplied from the battery 608 is provided. The time measured by the timer 607 is stored in a nonvolatile memory 609 such as an EEPROM. As the nonvolatile memory, FeRAM, MRAM or the like may be used in addition to the EEPROM.

  Since this recording apparatus is for both AC power supply and DC (battery) power supply, even if the AC adapter is pulled out while AC power is supplied from an AC adapter (not shown), The power can be supplied from the DC (battery) and the operation can be continued. For this reason, this recording apparatus is provided with a mechanism for discriminating between AC adapter driving and battery driving. Since such a mechanism is known, detailed description thereof is omitted here.

  FIG. 5 is a block diagram showing a detailed configuration of the peripheral part and the power supply part of the USB interface. This printer can directly input from a digital camera or digital video compatible with PictBridge via a USB interface.

  The printer 800 includes a battery voltage detection mechanism and a mechanism for estimating the remaining battery level from the battery voltage detected by the battery voltage detection mechanism. 5 is a diagram showing a detailed configuration of the peripheral portion and the power supply unit of the USB interface, the same reference numerals are given to the components already described in FIG. 4, and the description thereof is omitted here. Only the parts not mentioned in FIG. 4 will be described.

  The MPU 601 and the ROM 602 are connected by a ROM bus 618. Further, a USB host controller 616 is connected to the MPU 601, and manages the data transfer between the printer and the PictBridge compatible digital camera connected to the USB port 611a.

  Either the power from the AC adapter (not shown) via the DCin jack 817 or the power from the battery 608 is input to the DC-DC converter 614. The DC-DC converter 614 converts the input voltage into a voltage necessary for the printer 800. The regulator 613 converts the input voltage from the DC-DC converter 614 to 5 V for the USB Vbus and outputs it. The Vbus switch 612 is controlled to be turned on / off by the MPU 601 via the Vbus switch control line 617.

  When the Vbus switch 612 is ON, power can be supplied to the USB device (for example, a digital camera) connected to the USB port 611a via the Vbus from the regulator 613. On the other hand, when the Vbus switch 612 is OFF, the power supply from the Vbus can be cut off.

  Now, the input voltage from the battery 608 is divided by a resistor and input to the AD port of the MPU 601 as shown in the figure. With this mechanism, the MPU 601 can always detect the voltage of the battery 608 and can compare the voltage table stored in the ROM 602 with the detected voltage to estimate the remaining battery level.

  Next, the battery voltage detection sequence will be described.

  FIG. 6 is a flowchart showing a battery voltage detection sequence.

  The printer 800 includes a plurality of motors (for example, a carriage motor and a conveyance motor) and the recording head 105, and each is driven in an independent sequence, so the load is not constant. On the other hand, in order to estimate the remaining battery level from the battery voltage, the load must be in a constant state, so the battery voltage detection is performed according to a prescribed sequence so that it is performed at a timing when the load becomes constant. . When the bus-powered device is connected to the USB port, the current increases because Vbus is supplied, and the battery voltage temporarily decreases by a certain amount.

First, in step S201, Vbus is turned on, waits for 100 ms, and then the battery voltage (V _on ) is detected.
Next, in step S202, it is checked whether or not the D + terminal of the USB port 611a is pulled up to, for example, 5V. Here, if it is determined that the D + terminal is pulled up, it is determined that a device conforming to the USB standard may be connected, and the process proceeds to step S203. In this case, the MPU 105 starts enumeration with the connected USB device. On the other hand, if it is determined that the D + terminal is not pulled up, it is determined that a device conforming to the USB standard is not connected, and the process proceeds to step S206. According to the USB specification, the USB device must pull up the D + terminal to 5 V within 100 ms after power is supplied to Vbus.

In step S203, the newly detected battery voltage is compared with the previously detected voltage to check whether the voltage drop of the newly detected battery voltage is equal to or greater than a certain value. Here, if the voltage drop is above a certain level, the load may increase because Vbus power is supplied to a device that does not conform to the USB standard connected to the USB port 611a. Determination is made, and the process proceeds to step S204. Then, Vbus is turned _off to detect the battery voltage (V _off ). On the other hand, if the voltage drop is less than a certain value, the process returns to step S201 to perform normal battery voltage detection.

In step S204, when Vbus is turned off, power supply from Vbus is stopped, so that the load is predicted to decrease. Therefore, in step S205, the battery voltage detection result (V _off ) in step S204 is compared with the battery voltage detection result (V _on ) in step S201, and whether the voltage increase is a constant value (V ₀ ). Find out. Here, if V _off −V _on ≧ V _0, it is determined that the voltage rise is a certain value or more, and it is determined that a device that does not conform to the USB standard is connected to the USB port 611a. The process proceeds to step S206. On the other hand, if V _off −V _on <V ₀ , the process returns to step S201 to perform normal battery voltage detection.

  In step S206, the arbitrary time Vbus set in the printer 800 is kept OFF, and power supply from the Vbus is prohibited for a device that does not comply with the USB standard. In this way, if it is confirmed that a bus-powered device that does not comply with the USB standard is connected, the power supply by Vbus is turned off for a certain period of time as necessary, thereby suppressing the power consumption of the battery. Is possible.

  However, if the power supply to Vbus is turned off for a certain time, it is necessary to turn it on for 100 ms in preparation for newly connecting a USB device.

  Note that the sequence of steps S201 to S205 may be performed a plurality of times in order to more accurately determine whether the connected device conforms to the USB standard.

  Therefore, according to the embodiment described above, for example, a bus-powered device that does not comply with the USB standard is connected to a USB port prepared exclusively for connection with a device that conforms to the USB standard such as a PictBridge compatible device. However, since it is prohibited to continue power supply from Vbus, waste of battery power of the battery-driven type printer as in this embodiment is prevented and power supply to unnecessary loads is stopped. It is possible to reduce the load and improve the accuracy of the battery remaining amount detection mechanism that is originally provided.

  In this embodiment, a battery-driven printer having a USB port has been described as an example. However, the present invention is not limited to this. For example, the present invention can be applied to a laptop personal computer provided with a USB port, a palmtop personal digital assistant (PDA), and the like.

  As an application example of the present invention, a portable electronic device that can be driven by a battery power source, for example, a printer having a dedicated USB port for connecting a PictBridge compatible device is conceivable. In particular, it is effective when the USB port is used exclusively for connection of a device for a specific purpose (for example, a digital camera or digital video compatible with PictBridge) as a specific application.

1 is an external perspective view showing an outline of the overall configuration of an ink jet recording apparatus that is a typical embodiment of the present invention. It is a perspective view which shows the state which mounted | wore the battery charger with the inkjet printer shown in FIG. 2 is a perspective view illustrating an internal configuration of a printer 800. FIG. FIG. 4 is a block diagram illustrating a control configuration of the printer 800 illustrated in FIGS. 1 to 3. It is a circuit diagram which shows the control structure relevant to electric power supply. It is a flowchart which judges whether the bus powered device is connected to the USB port.

Explanation of symbols

601 MPU
602 ROM
604 RAM
608 Battery 611a USB port 612 Vbus switch
613 Regulator 614 DC-DC converter 616 USB host controller 617 Vbus switch control line

Claims (6)

An electronic device that can be connected to an external device via a USB interface and can be driven by a battery power source,
A bus for supplying power to an external device connected via the USB interface;
A switch for turning ON / OFF the power supply via the bus;
Determining means for determining whether an external device connected via the USB interface is a device compliant with the USB standard;
An electronic apparatus comprising: a control unit that controls power supply to the external device using the switch according to a determination result by the determination unit. The determining means includes
First measuring means for measuring a battery voltage when power is supplied to the external device via the bus;
A first discriminating unit that compares a plurality of battery voltages measured by the first measuring unit and discriminates whether or not there is a voltage drop of a predetermined value or more between the previous measurement result and the current measurement result. When,
In accordance with the determination result by the first determination means, the second measurement means for stopping the power supply to the external device via the bus and measuring the battery voltage when the power supply is not performed;
Whether the battery voltage measured by the first and second measuring means is compared, and the battery voltage when the power supply is not performed is increased by a predetermined value or more from the battery voltage when the power supply is performed Second determining means for determining whether or not
2. The electronic device according to claim 1, wherein whether or not the connected external device is a device compliant with the USB standard is determined according to a determination result by the second determination unit. The determining means further includes third determining means for determining whether or not a voltage of a specific signal line of the USB interface is pulled up to a predetermined voltage,
3. The electronic device according to claim 2, wherein whether or not the connected external device is a device compliant with the USB standard is determined according to a determination result by the third determination unit.   4. The electronic apparatus according to claim 1, further comprising a battery remaining amount detecting unit that detects a remaining amount of the battery according to a voltage detection method. The electronic device is a printer;
5. The electronic device according to claim 1, wherein the external device conforming to the USB standard is a device corresponding to PictBridge. A power supply control method for an electronic device that can be connected to an external device via a USB interface and can supply power to the external device via a bus and can be driven by a battery power source,
A determination step of determining whether an external device connected via the USB interface is a device compliant with the USB standard;
A control step of controlling power supply to the external device using a switch for turning ON / OFF the power supply via the bus according to a determination result in the determination step. Method.

Images