JP2013080392A - Usb charging for portable device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily charge a storage battery with current supplied from a USB-connected host device even in a portable device incorporating a storage battery which is too consumed to start.SOLUTION: A portable device is recognized as a charging dedicated device by a USB-connected host device to receive supply of high current from the host device, and not only stopping current supply to a main part unnecessary for charging but also bringing a control unit for supplying current to each part of the portable device into a standby state, charging current is increased as much as possible.

Description

  The present invention relates to a portable device and a charging system for charging a built-in storage battery, and more particularly to a portable device and a charging system for charging a built-in storage battery using a current provided from a host device via a USB cable.

  Rechargeable storage batteries (hereinafter referred to as batteries) are widely used as power sources for portable devices such as electronic cameras and IC recorders. Usually, these portable devices are provided with an AC adapter, and the battery in the portable device is charged via the AC adapter, or a dedicated charger is attached, and the battery removed from the portable device is attached to the charger. Install and charge.

  On the other hand, when a portable device is connected to a host device such as a PC using a USB (Universal Serial Bus) interface with a cable, a constant current can be supplied from the host device. The current can be used to charge the battery. In Patent Document 1, in a digital camera connected to a host device via a USB cable, when the current supplied from the host device is high current (500 mA), the battery is charged, and the supplied current is low current (100 mA). In this case, it is described that the battery is not charged and communication standby is performed with the supplied current.

  JP 2010-287115 A

  According to the USB 2.0 standard, the current that the portable device can receive from the host device via the USB cable can be up to 500 mA (high current) in the configuration state (configured), and the non-configuration state (Unconfigured) is possible up to 100 mA (low current). If the battery is so drained that the portable device cannot be activated, the portable device cannot execute the processing necessary to enter the configuration state to receive a high current supply, and the low current supplied from the host device. Will continue charging.

  The present invention has been made in view of the above problems, and even when the storage battery is exhausted and cannot be started, internal charging can be performed in a short time by receiving a high current supplied from a host device connected by a USB cable. An object of the present invention is to realize a portable device and a charging system including the portable device.

  In order to achieve the above object, the portable device of the present invention is a portable device capable of charging a built-in storage battery by a current supplied from the host device via a USB interface when connected to the host device via USB. A communication unit that communicates with the host device via the USB interface; a charging unit that measures a remaining amount of power of the storage battery and charges the storage battery with a current supplied via the USB interface; and the portable device The mobile unit excluding the control unit that controls each part of the mobile phone, the connection detection unit that detects that the host device is connected via the USB interface, the communication unit, the charging unit, the control unit, and the connection detection unit. A main circuit portion of the device, and the control unit is connected to the host device via the USB interface. The communication unit, the remaining amount detection unit, the charging unit, and the control unit excluding the main part are operated with power of a first current amount supplied from the host device, and the charging unit measures the When the remaining power of the storage battery is equal to or less than a predetermined threshold that can activate the portable device, set the parameters defined in the USB standard so that the host device recognizes the portable device as a charge-only device, and The host device that has recognized the portable device as the charge-only device is supplied with power of a second current amount larger than the first current amount, and the charging is performed while the supply of current to the main circuit portion is stopped. And charging the storage battery with the second current amount, and setting the control unit to a standby state with low power consumption.

  The charging system of the present invention includes a portable device and a host device connected via USB, and the portable device includes a first communication unit that communicates with the host device via a USB interface, and a remaining power of the storage battery. The charging unit that measures the amount and charges the storage battery with the current supplied through the USB interface, the control unit that controls each part of the portable device, and the host device through the USB interface And a main circuit part of the portable device excluding the first communication unit, the charging unit, the control unit, and the connection detection unit, and the host device has a USB interface. A second communication unit that communicates with the portable device via the USB interface, a power supply unit that supplies power to the portable device via the USB interface, and the power supply. A current switching unit that switches the power provided by the providing unit from a first current amount to a second current amount that is greater than the first current amount, and the control unit of the portable device is configured via the USB interface. When connected to the host device, the first communication unit, the charging unit, the control unit, and the connection detection unit excluding the main circuit portion are operated by the power of the first current amount supplied from the host device. When the remaining power of the storage battery measured by the charging unit is less than or equal to a predetermined threshold that can activate the portable device, a predetermined parameter defined in the USB standard is set as a dedicated charging device, and the host device The current switching unit is configured to supply a current to be supplied to the portable device when the predetermined parameter acquired from the portable device by the second communication unit represents the charging device. The flow rate is switched to the second current amount, and the control unit of the portable device stops the supply of current to the main circuit portion, and the second current amount supplied from the host device to the charging unit And charging the storage battery and putting the control unit in a standby state with low power consumption.

  According to the present invention, even a portable device with a built-in storage battery that cannot be started up can be charged at high speed with a current supplied from a USB-connected host device.

It is a block diagram which shows the structural example of the portable apparatus of the charging system which concerns on embodiment of this invention. It is a figure explaining the 1st method of charging Dead Battery prescribed | regulated by USB charge specification 1.2. It is a figure explaining the 2nd method of charging Dead Battery prescribed | regulated by USB charge specification 1.2. It is a figure which shows the flow of charge of the digital camera which is a portable apparatus of the USB charging system which concerns on embodiment of this invention. It is a figure which shows the information processing of OS of the personal computer which is a host apparatus of the USB charging system which concerns on embodiment of this invention. It is a figure which shows the information processing of the charge driver of the personal computer which is a host apparatus of the USB charging system which concerns on embodiment of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a system configuration example of a digital camera (DSC) as an example of a portable device.

  The system control block 100 is a block that controls the overall operation of the digital camera and USB (Universal Serial Bus) communication, and includes a system controller 102 and a USB controller 103. The system controller 102 includes a CPU, a ROM that stores various programs for controlling the system, and a RAM that temporarily stores information.

  The camera block 101 is a block that executes photographing and image display, which are main functions of the digital camera, and includes an imaging circuit 110, an image processing circuit 111, a display circuit 112, and a memory controller.

  In this embodiment, power is supplied to each circuit of the digital camera by the rechargeable secondary battery 105 in the camera body, and the charge controller 104 controls the charging of the secondary battery 105 and the remaining power. Output quantity.

  The USB controller 103 and the charge controller 104 are connected to a PC (personal computer), which is a host device, via a USB port 106 and a USB cable. The D + line and D− line of the USB port 106 are data lines for communicating with the host device, and the VBUS line is a power line through which a current supplied from the host flows. One end of the pull-up resistor 108 is connected to the positive electrode of the secondary battery, and the D + terminal can be pulled up by turning on the switch 109 by the system controller 102.

  The imaging circuit 110 of the camera block 101 is composed of a CCD or CMOS image sensor and a circuit for driving them, and converts a subject image formed on the surface of the image sensor by an imaging optical system into an image signal and outputs the image signal. The image processing circuit 111 includes an AD conversion circuit, an image forming circuit, and a compression / decompression circuit. The AD conversion circuit converts an analog image signal output from the imaging circuit 110 into a digital image signal. The image forming circuit is a digital image signal. Are processed to generate color image data, and the compression / decompression circuit compresses the color image data and then generates an image file. The memory controller 113 includes a memory card interface, and stores the image file generated by the image processing circuit 111 in a memory card including a nonvolatile memory attached to the memory card interface.

  The display circuit 112 includes a liquid crystal display panel and a liquid crystal driving circuit that drives the liquid crystal panel. The image file read from the memory card by the memory controller 113 is decompressed by the compression / expansion circuit of the image processing circuit 111 and then reduced, and is displayed on the liquid crystal panel by the liquid crystal driving circuit. In the display circuit 112, the image processing circuit 111 processes the image signal output by the photographing circuit 110 and outputs the video image, and displays the moving image as a preview image on the liquid crystal panel.

  Each circuit constituting the system control block 100 and the camera block 101 is connected via a system bus 114. The system controller 102 and the charge controller 104 exchange VBATAD signals, ISEL signals, and CHDEND signals. The VBATAD signal output from the charge controller 104 is a signal representing the remaining power of the secondary battery 105, and the CHDEND signal is a signal for notifying the system controller 102 that charging is complete. On the other hand, the ISEL signal output from the system controller 102 is a signal that controls the current that the charge controller 104 receives from the host device via the VBUS line.

  Electric power VDD is supplied from the secondary battery 105 to each circuit of the system control block 100 and the camera block 101. The power supplied to each circuit of the camera block 101 is turned on / off by a switch 107 controlled by a signal VDDSEL output from the system controller. When the camera is activated, the switch 107 is OFF, and no power is supplied to each circuit of the camera block 101.

  The USB battery charging specification 1.2 (Battery Charging Specification Revision 1.2) defines two methods for charging a storage battery (Dead Battery) that has been consumed so that the device cannot be operated so that the device can be activated. .

  In the first method, even when a portable device (in this embodiment, a digital camera) is connected to the host device and the host device cannot identify the portable device (Unconfigured), the portable device is connected from the host device through the VBUS line. It can be charged for 45 minutes using the supplied 100 mA current. In this method, the terminal device does not need to perform USB communication with the host device. As shown in FIG. 2A, since only the charge controller 104 needs to operate, most of the supplied current can be applied to the charging of the secondary battery 105. However, since the current supplied from the host is as small as 100 mA, charging takes time.

  In the second method, the portable device is supplied with a current of up to 500 mA through the VBUS line for 15 minutes. The host device identifies the portable device and is partially communicable (configured). It must respond to the transmitted token with a NAK or other valid response that informs it that normal data communication is not possible. Therefore, as shown in FIG. 2B, since the charge controller 104, the system controller 102, and the USB controller 103 need to operate, a part of the current supplied from the host is consumed by these circuits. .

The charging system of the present embodiment will be described with reference to FIGS. FIG. 3 is a charging flow of the digital camera.
When the USB cable is connected to the PC which is the host device in step S100, a current of 100 mA is supplied from the PC via the VBUS. The charge controller supplies this 100 mA current to each circuit included in the system control block.

  In step S <b> 101, whether the system controller 102 reaches the amount of power required for starting the digital camera by the value of VBATAD output from the charge controller 104, so that the remaining power of the secondary battery 105 (remaining battery) is reached. Determine whether or not. If it is determined that the remaining battery capacity of the secondary battery is not enough to activate the digital camera, the process proceeds to step S102. If the remaining battery capacity is sufficient to activate the digital camera, the process proceeds to step S111.

  In step S102, the system controller 102 sets the descriptor (data structure storing data of the entire portable device defined by the USB specification) as a dedicated device for charging in order to recognize the digital camera as a dedicated device for charging. And the required bus current is set to 500 mA. The PC acquires the contents of this descriptor to detect that the charging-only device is connected.

  In step S103, the switch 109 of the pull-up resistor 108 for the D + data line is turned ON. In step S104, negotiation with the PC is performed, and the contents of the descriptor are acquired by the PC. In this process, the PC recognizes the digital camera as a charge-only device.

  In step S105, reception of a Set_Configuration request transmitted from the PC is awaited. When a Set_Configuration request is received, a current supply of up to 500 mA (900 mA for USB 3.0) can be received via the VBUS line.

  After receiving the Set_Configuration request, in step S106, the system controller 102 switches the current drawn by the charge controller 104 to 500 mA using the ISEL signal.

  Since only the SOF (Start of Frame) is transmitted from the PC and no meaningful data is transmitted, the USB controller 103 only needs to skip the received SOF. SOF is sent on the D + and D- lines, but there is no SOF response. Therefore, the power consumption can be reduced by changing the system controller 102 to the standby state in step S107. As a result, more of the 500 mA current supplied via VBUS can be used for charging the secondary battery. Since SOF reception continues, only the signals on the D + and D- lines are active.

  In step S108, LOOP is repeated until charging is completed. When the voltage of the secondary battery 105 exceeds a predetermined threshold, the charge controller 104 determines that charging of the secondary battery 105 has been completed. Although it is LOOP in the flow of FIG. 3, since the system controller is in the standby state, the CPU is in the WAIT state.

  In step 109, the charge completion signal CHGEND output from the charge controller 104 is input to the system controller 102, and the system controller 102 returns from the standby state and returns to the normal operation state.

  In step S110, the switch 109 of the pull-up resistor 108 on the D + line is turned off to disconnect the USB communication with the PC. In step 111, the switch 107 is turned on by the VDDSEL signal output from the system controller 102 to supply power to each circuit included in the camera block 101.

  In step S112, the descriptor is set as a standard device (in this case, a mass storage device), and the switch 109 of the pull-up resistor 108 is turned ON in step S113 to reconnect to the PC. As a result, the digital camera is connected to the PC as mass storage.

  Next, the processing procedure of the PC OS and the charging driver corresponding to the charging flow of the digital camera described in FIG. 3 will be described. In the present embodiment, a charging driver must be installed in order for the PC to recognize the digital camera as a charging-only device. However, this is not the case when the OS is prepared in advance. By the way, the charging driver is detected as an unknown device when the USB cable is connected, and may be installed at that time, or it is installed in advance and the corresponding driver is recognized and valid when the USB cable is connected. May be.

  FIG. 4 is a processing flow of the OS of the PC at the time of USB connection.

  In step S200, the PC recognizes that the digital camera is connected by detecting that the D + line of the USB port is pulled up. After the connection, in step S201, the PC and the digital camera perform negotiation processing with each other (corresponding to S104 in FIG. 3).

  After the negotiation, in step S202, the PC acquires a descriptor from the digital camera, and in step S203, determines whether the descriptor represents a charge-only device. If the determination is NO, the digital camera is connected as a mass storage device, and processing as a mass storage device is executed (step S209). Note that the connection of the digital camera as a mass storage device is terminated when it is detected that the pull-up of the D + line is turned off (step S210).

  If YES is determined in step S203, the OS starts after loading the dedicated charge driver in steps S204 and S205, and the control is transferred to the charge driver.

  When the OS passes control to the charging driver, the OS continues to transmit a SOF (Start of Frame) packet to prevent transition to a suspended state in which communication with the portable device is stopped (step 206). In step S207, when it is detected that the pull-up of the D + line of the USB port is OFF, the OS unloads the charge driver in step S208 and ends the process.

  FIG. 5 illustrates a processing flow of the charge driver loaded in step S204.

  In step S300, a descriptor is acquired from the digital camera. In step S301, a Set_Configuration request is transmitted so that the digital camera can be supplied with a current of 500 mA.

  After that, it waits for an unload instruction from the OS. When unloading is instructed from the OS, the resources (memory) used by the charge driver are released and the process is terminated.

  As described above, in the digital camera according to the present embodiment, after the current drawn by the charge controller 104 is switched to 500 mA in step S106, the system controller can be put into a standby state in step S107. Thus, the charging time can be shortened.

  In this embodiment mode, the present invention has been described in the case of a personal computer (PC) as a host device and a digital camera as a portable device, but the portable device is a device driven by a storage battery such as a video camera, an IC recorder, or a music player. I just need it. The host device may be any device having a USB host function to which power is supplied from an AC power source or a large capacity battery.

DESCRIPTION OF SYMBOLS 1 ... Digital camera 100 ... System control block 101 ... Camera block 102 ... System controller 103 ... USB controller 104 ... Charge controller 105 ... Secondary battery 106 ... USB port 107 ... Switch 108 ... Pull-up resistor 109 ... Switch 110 ... Imaging circuit 111 Image processing circuit 112 Display circuit 113 Memory controller 114 System bus

Claims (4)

A portable device capable of charging a built-in storage battery with a current supplied from the host device via a USB interface when connected to the host device via USB,
A communication unit that communicates with the host device via the USB interface;
A charging unit that measures the remaining power of the storage battery and charges the storage battery with a current supplied via the USB interface;
A control unit for controlling each part of the portable device;
A connection detection unit for detecting connection with the host device via the USB interface;
The main circuit portion of the portable device excluding the communication unit, the charging unit, the control unit, and the connection detection unit,
When the control unit is connected to the host device via the USB interface, the communication unit excluding the main part with the power of the first current amount supplied from the host device, the remaining amount detection unit, Operate the charging unit and the control unit,
It is defined in the USB standard so that the host device recognizes the portable device as a charge-only device when the remaining power of the storage battery measured by the charging unit is equal to or less than a predetermined threshold that can activate the portable device. And receiving a power supply of a second current amount larger than the first current amount from the host device that has recognized the portable device as the charge-only device,
While the supply of current to the main circuit portion is stopped, the charging unit is charged with the storage battery with the second current amount, and the control unit is placed in a standby state with low power consumption. .   The portable device is a digital camera, and the main circuit part is an imaging unit that captures a subject and converts it into an electrical signal, an image processing unit that processes the electrical signal output from the imaging unit and generates image data, The portable device according to claim 2, further comprising: a memory that stores image data reproduced by the image processing unit as an image file in a recording medium; and a display unit that displays the image data. A system in which a host device and a portable device operating with a storage battery are connected via USB,
The portable device is:
A first communication unit that communicates with the host device via a USB interface;
A charging unit that measures the remaining power of the storage battery and charges the storage battery with a current supplied via the USB interface;
A control unit for controlling each part of the portable device;
A connection detection unit for detecting connection with the host device via the USB interface;
The main circuit portion of the portable device excluding the first communication unit, the charging unit, the control unit, and the connection detection unit,
The host device is
A second communication unit that communicates with the portable device via a USB interface;
A power supply unit for supplying power to the portable device via the USB interface;
A current switching unit that switches the power provided by the power providing unit from a first current amount to a second current amount greater than the first current amount;
When the control unit of the portable device is connected to the host device via the USB interface, the first communication excluding the main circuit portion with the power of the first current amount supplied from the host device. Operation unit, charging unit, control unit and connection detection unit,
When the remaining power of the storage battery measured by the charging unit is less than or equal to a predetermined threshold that can activate the portable device, a predetermined parameter defined in the USB standard is set as a dedicated charging device,
The current switching unit of the host device, when the predetermined parameter acquired from the portable device by the second communication unit represents the charging device, the current supplied to the portable device from the first current amount Switch to the second amount of current,
The control unit of the portable device causes the charging unit to charge the storage battery with the second amount of current supplied from the host device while stopping the supply of current to the main circuit portion, and the control unit A charging system characterized by a standby state with low power consumption.   The portable device is a digital camera, and the main circuit part is an imaging unit that captures a subject and converts it into an electrical signal, an image processing unit that processes the electrical signal output from the imaging unit and generates image data, The portable device according to claim 2, further comprising: a memory that stores image data reproduced by the image processing unit as an image file in a recording medium; and a display unit that displays the image data.

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