JP2006085248A - Portable apparatus having host function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily secure power for sufficiently assuring the operation of a portable apparatus having a USB host function. <P>SOLUTION: By an external power input detection part 3, whether or not external power is inputted is detected. If the portable apparatus is operated by internal power 4 and a device apparatus operated by bus power is connected, power is not supplied to the device apparatus. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a portable device having a data communication unit with a connected device such as a host function and a power supply unit to the connected device.

  USB is a method for connecting the peripheral device to a personal computer. In USB, a personal computer functions as a host and a peripheral device functions as a device. USB connects the host and multiple devices via serial communication, and plug and play (a function that automatically recognizes the connection when a peripheral device is newly connected or deleted), hot inserter, etc. Functions (functions that can be connected and disconnected while the host power is on) and power supply functions.

  For the USB connection, a total of four wires including a 5V power source called VBUS, GND, and a combination of D + and D-2 signal lines are to be performed by a dedicated connector. There is a limit to the current value that can be supplied by this power source, and the USB standard is limited to 100 mA to 500 mA. In USB, it is defined that a peripheral device must be in a suspended state by a command from a host. In this state, current consumption from VBUS must be reduced to 500 μA. There is a resume command for returning from the suspended state.

  In recent years, it is possible to control not only a personal computer as a device equipped with a USB host function, but also a printer having a USB host function that can be connected to a digital camera having a USB device function, and conversely a printer having a USB device function. Devices such as digital cameras having a USB host function have become available.

Devices with a USB device function receive power supply from devices that have their own power supply unit and operate (self-powered) and devices that have a USB host function through a USB communication cable without having a power supply unit themselves. There are two types of devices that operate (bus power). In order to solve the problem in the case where the power consumption of the USB device in this connection method exceeds the power supply amount of the USB host, in Japanese Patent Laid-Open No. 2001-077562, a power supply built in the electronic device from the power supply built in the electronic device An invention has been proposed in which the power supply to the connected device is limited by comparing the power supply amount of the connected device with the power consumption amount of the connected device.
JP 2001-077562 A

  However, in the conventional method, when a portable device having a USB host function has only a power capacity that guarantees the operation of the portable device body, when a device having a USB device function of bus power operation is connected, At the moment when the power consumption exceeds the power supply amount of the USB host, both the USB host and the USB device are disabled. Even if the USB device operates normally, if the power of the USB host is excessively consumed, the operation of the USB host main body, for example, if the printer is used, the printing operation cannot be sufficiently guaranteed.

  In Japanese Patent Laid-Open No. 2001-077562, in order to limit power supply to a connected device, the USB host power supply capacity, power supply amount, and USB device power consumption are detected and monitored. A complicated electric circuit and control such as comparing the power supply amount and the power consumption amount of the USB device are required.

  In order to achieve the above object, in claim 1 of the present invention, a portable device having a host function performs input of an external power supply, for example, by means of detecting whether or not an external power supply is input from an AC adapter. If the external power supply is not input, the mobile device has a power supply switching means that operates with a secondary battery such as a rechargeable battery. This portable device has means for supplying power to a device having a device function connected through communication means, such as USB. Further, the portable device having the host function has a determination means for determining whether the device having the device function to be connected operates by self power or bus power, and the portable device having the host function is a secondary battery. When a device having a device function to be connected operates on bus power, the communication is cut off without supplying power to the device.

  According to a second aspect of the present invention, when a portable device having a host function is operated by an external power source and a device having a device function to be connected operates by bus power, power is supplied to the device.

  When the device having the device function to be connected operates by self-power according to claim 3, the device is connected to the device regardless of whether the portable device having the host function is operated by an external power source or a secondary battery. The communication operation is performed without supplying the power.

  In Claim 4, when the portable device having the host function is operated by the secondary battery and the device having the device function to be connected is operated by the bus power, the communication is cut off without supplying power to the device. Before performing, it communicates information indicating that communication is impossible to the device and displays error information on a portable device having a host function.

  By using the means of claims 1 to 4, in the portable device having the host function, the connection of the device having the device function allows the operation of the portable device having the host function without using a complicated electric circuit or control. It is possible to easily secure a power source that can be sufficiently guaranteed.

  According to the present invention, when a portable device having a host function that operates on a secondary battery is connected to a device having a device function that operates on bus power, power is supplied to the device without using a complicated electric circuit or control. Therefore, it is possible to easily secure a power source that can sufficiently guarantee the operation of the portable device having the host function thereafter.

  In addition, when a device having a device function to be connected operates with bus power, power to the device having a device function can be obtained by operating a portable device having a host function with external stable power such as an AC adapter. Enable supply and communication.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating an embodiment of a portable device having a USB host function according to the present invention. In the figure, reference numeral 1 denotes a control circuit, which is a function that shows the original operation of a portable device having a CPU, RAM, ROM, and USB host function (not shown), for example, an operation unit and a printing unit as a printing function if a printer. In the case of a digital camera, the digital camera function includes a camera unit, an operation unit, a photographic image storage unit, and the like.

  The control circuit 1 performs communication control with a device having a USB device function in accordance with a user instruction according to a program stored in advance in the ROM, for example, a function indicating the original operation of a portable device having a USB host function, such as a printer If it is, print control of the data received by the communication means, if it is a digital camera, take a picture and store it as an image file, play back the stored image file, photographed image file or stored image file Or the stored image file is controlled to be transferred by communication means.

  Reference numeral 2 denotes a terminal for inputting an external power source such as an AC adapter to a portable device having a USB host function. By 3, it is detected whether the AD adapter is connected to the external input terminal 2 and power is supplied.

  Reference numeral 4 denotes a secondary battery that supplies normal power to a portable device having a USB host function, and includes any one of an alkaline battery, a nickel cadmium battery, a nickel metal hydride battery, a lithium ion battery, and the like.

  Reference numeral 5 denotes a switch that switches between the external power input 2 and the secondary battery 4 for supplying power to the portable device having the USB host function by the external power input detection 3.

  6 is a communication means, a function for detecting whether a device having a USB device function is connected to the communication terminal 7, a function for detecting whether the connected device operates by self power or bus power, connection A function of supplying power to a device having a UDB device function and a function of data transfer and the like are performed.

  Reference numeral 8 denotes a display device for transmitting error information to the user when an error state occurs, and is configured by an LCD display, an LED, a buzzer, or the like.

  FIG. 2 shows a flowchart of a program for realizing the present invention.

  In FIG. 2, the control circuit 1 performs an operation power supply switching process and a communication process with the USB device. A portable device having a USB host function starts operation by a user operation, and in step S10, the external power input detector 3 detects whether or not an external power is being input from the external power input terminal 2. If an external power source is input, the power source switch 5 is used to switch the operating power source of the portable device to the external power source in step S20. If the external power is not input, the operating power source of the portable device is switched to the secondary battery 4 attached to the portable device using the power switch 5 in step S30.

  In step S40, the communication means 6 detects whether or not a device having a USB device function is connected to the communication terminal 7. If not detected, the process proceeds to external power input detection in step S10, and the detection of the USB device is monitored again in step S40.

  In step S50, when the communication means 6 detects that the USB device is connected to the communication terminal 7, the portable device shifts to an operation mode that allows a maximum current of 100 mA conforming to the USB to the connected device.

  A device request is made in step S60, and is necessary for various communications with the USB device connected to the communication terminal 7, such as data transfer direction, connection device address setting, connection device configuration, and device descriptor setting. Make basic settings.

  In step S70, a device descriptor that is information about a connected USB device, such as a communication protocol, a USB vendor ID, a product ID, an index to a string descriptor representing the manufacturer, product, and manufacturing number of the connected device, is acquired. .

  In step S80, the configuration is information regarding the configuration of the connected USB device, such as information on whether the connected USB device operates with self power or bus power and the power consumption required by the USB device. Get descriptor.

  In step S90, it is determined from the configuration descriptor information acquired in step S80 whether the connected USB device operates with self power or bus power.

  If it is determined in step S90 that the USB device operates with bus power, in step S100, the external power input detector 3 detects whether or not the external power is input from the external power input terminal 2 in the same manner as in step S10. Do. When the external power supply is not input and the secondary battery 4 is operating, the process proceeds to error processing after step S110.

  In step S110, error information indicating that communication processing cannot be normally performed is transmitted to the USB device, and connection of the USB device is prohibited in step S120. In step S130, power supply started to be supplied in the operation mode selected in step S50 is stopped, and in step S140, a USB suspend mode is entered. In this suspend operation mode, the current supplied to the connected USB device is set to a current value as small as 500 μA at the maximum, and the influence on the power supply on the portable device side having the USB host function is minimized. In step S150, an error is displayed on the display device 8, the user is notified that the connected USB device does not operate normally with the secondary power source of the portable device having the USB host function, and the process is terminated.

  Here, the process proceeds to the external power supply input detection in step S10, and the user can wait for the input of the external power supply. If an external power input is detected in step S10, the USB device that has transitioned to the suspend operation mode is restored by a resume command, and then normal communication processing from step S160 described later is performed.

  If it is determined in step S100 that an external power supply has been input and the apparatus is operating with the input external power supply, the process proceeds to communication processing in and after step S160.

  Since sufficient power can be supplied to drive the connected USB device, more detailed communication setting is performed in step S160, and the connection with the connected USB device is completed in step S170. In step S180, power is supplied to the connected USB device. In step S190, a communication operation such as data transfer is executed, and the communication process is terminated.

  If the USB device connected in step 90 is assumed to operate with self-power, in step S200, more detailed communication settings necessary for communication are performed in the same manner as in step S160 described above. The connection with the connected USB device is completed in the same manner as in step S170. Since it is not necessary to supply power to the connected USB device, communication processing such as data transfer is executed in step S220 in the same manner as in step S190 without performing power supply in step S180. Exit.

  In this embodiment, the communication method is described as USB. However, in communication with a device connected to a communication connector, communication having a power supply line for supplying power to the connected device in addition to the data signal line. If it is a system, it is not necessary to limit a communication system to USB. For example, it may be IEEE 1394 or a PC CARD interface.

  The embodiment of the present invention may be any portable device having a USB host function, and is not limited to a digital camera and a printer, and can be applied to various portable devices such as a PDA, a handheld computer, and a cellular phone.

It is a block diagram which shows the structure of the portable apparatus which has a USB host function. It is a flowchart which shows the communication processing in the portable apparatus which has a USB host function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control circuit 2 External power supply input terminal 3 External power supply input detector 4 Secondary battery 5 Power supply switch 6 Communication means 7 Communication terminal 8 Display

Claims (4)

A means for detecting whether or not an external power supply is input, and when the external power supply is input, operates with an external power supply, and when the external power supply is not input, a built-in secondary battery In a portable device having a power supply switching means that operates in
The portable device has a communication means with a connection device and a power supply means by the communication means,
Means for detecting, by the communication means, whether the device connected to the portable device operates by self-power or bus power by connection;
When the portable device operates with a secondary battery and the connection device operates with bus power, the connection device is connected to the connection device without the power supply by the power supply device. A portable device having a host function characterized by blocking.   2. The host according to claim 1, wherein when the portable device operates with an external power source and the connection device operates with bus power, the power supply unit supplies power to the connection device. A portable device with functions.   When the connected device operates with self-power, the power supply means supplies power to the connected device regardless of whether the portable device operates with an external power source or a secondary battery. The portable device having a host function according to claim 1, wherein the communication unit performs a communication operation with the connection device without performing communication.   When the portable device is operated with a secondary battery and the connected device is operated with bus power, the power supply means does not supply power before the connection with the connected device is cut off by the communication means, A portable device having a host function, wherein error information is transmitted to the connection device by the communication means, and error display is performed by the portable device.

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