JP2004280747A - Electronic apparatus, power supply control method of electronic apparatus and power supply control program of electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that an electronic apparatus cannot be operated by use of USB (universal serial bus) power when the electronic apparatus with a current consumption in starting exceeding 100 mA is connected to a USB host. <P>SOLUTION: The electronic apparatus the power consumption of which exceeds 5V, 100 mA at the start-up in a communicable state by USB is started by its own power source to perform transmitting and receiving of device information with the USB host. When it is determined that the USB host is outputtable of a bus power current of 500 mA, the power consumption is switched from its self power source to the use of bus power via a USB port, and the power consumption of the own power source of the electronic apparatus is suppressed only to the starting time to enable long-time data communication with the USB host. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic device that can use both power supply from a self-power supply and power supply from a communication interface.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electronic device connected as a peripheral device to a host device such as a personal computer via a communication interface, for example, a USB (Universal Serial Bus) interface, starts up when the flowing current value is within a current limit value of 100 mA and the USB device is activated. If the electronic device can be configured by communication, the electronic device can operate using power supplied via a USB interface (hereinafter, referred to as USB bus power) as a power supply. In addition, even if the electronic device has a capability of supplying a maximum of 500 mA of bus power to a host device and a USB hub connected by a USB interface, power exceeding 100 mA cannot be used without configuration. In addition, it is known that such a USB interface has a self-power supply so that an operation using self-power and an operation using USB bus power can be selected manually or automatically (for example, see Patent Document 1). It is also known to have a self-power supply, detect a USB connection state, and automatically turn off the self-power supply when not connected to reduce the power consumption of the self-power supply (for example, see Patent Document 2).
[0003]
[Patent Document 1]
JP-A-2002-94539
[Patent Document 2]
JP-A-2002-140136
[0004]
[Problems to be solved by the invention]
However, there has been a problem that when the above-described electronic device operates within a current value of 100 mA or less and cannot perform USB configuration, it cannot be operated using USB bus power as a power supply.
[0005]
The present invention has been made in view of such a conventional problem, and makes effective use of power supplied through a communication interface to minimize the power consumption of a self-power supply of an electronic device to reduce the remaining battery power. The purpose is to preserve.
[0006]
[Means for Solving the Problems]
According to an aspect of the present invention, there is provided an electronic apparatus connected to a host apparatus including a power supply unit for supplying power to an electronic apparatus connected via a communication interface. When the electronic device is started while being connected to the communication interface, if the current value required for the start exceeds the predetermined current value, the electronic device operates with power from its own power supply unit. Self-power supply means for requesting the host device to request power for maximizing a current value larger than the predetermined current value after being activated by the self-power supply means; and When power is supplied from a device that maximizes a current value larger than the predetermined current value, the power for the operation is changed to the power of the self-power supply unit. And it shall be equipped with a switching means for switching the power from al the host device.
[0007]
According to such a configuration, when the electronic device connected to the communication interface having the power supply capability starts, the power consumption of the electronic device exceeds the maximum power allowed by the power supplied via the communication interface. In such a case, the electronic device is activated by its own power supply, for example, a battery, and requests the power supply source supplied via the communication interface to increase the output for the power required for the operation of the electronic device. As a result, when the requested power is supplied from the power supply source supplied via the communication interface, the power consumption is switched from the self-power supply to the use of the power supplied via the communication interface, whereby the self-reliability of the electronic device is reduced. The power consumption of the power supply has been reduced and the remaining battery level can be preserved.
[0008]
According to the second aspect of the present invention, the first power supply means for supplying power that maximizes a predetermined current value to an electronic device connected via a communication interface, and a request from the electronic device. The electronic device is connected to a host device including a second power supply unit that supplies power to the electronic device to maximize a current value larger than the predetermined current value. Is a self-power supply means for self-supplying power required for operation, and a current value required when connected to the communication interface in an operating state using the power of the self-power supply means, Requesting means for requesting the host device to provide power for maximizing a current value larger than the predetermined current value when the current value exceeds a predetermined current value; When the power that maximizes a current value larger than the predetermined current value is supplied from the host device, the power for the operation is switched from the power of the self-power supply unit to the power from the host device. Switching means.
[0009]
According to such a configuration, when an electronic device operating on its own power, for example, a battery, is connected to a communication interface having a power supply capability, power consumption of the electronic device is supplied via the communication interface. If the maximum power allowed by the power is exceeded, the electronic device requests the power supply source supplied via the communication interface to increase the output for the power required for the operation of the electronic device. As a result, when the requested power is supplied from the power supply source supplied via the communication interface, the power consumption is switched to the use of the power supplied from the battery via the communication interface, thereby suppressing the power consumption of the battery. To save the remaining battery power.
[0010]
Further, according to the invention of claim 3, furthermore, power consumption storage means for storing maximum power consumption data for each operation mode of the electronic device, and maximum power consumption data in the current operation mode from the power consumption storage means. Data read means for reading, and the request means comprises request determination means for determining a current value required for the host device based on the maximum power consumption data in the current operation mode read by the read means. To do. According to such a configuration, the required power that is different for each operation mode of the electronic device is registered in the data memory in advance, so that the required power corresponding to the operation mode when connected to the communication interface is supplied. Since it can be requested originally, it has become possible to minimize the increase in required power.
[0011]
Further, according to the invention of claim 4, an external power supply input means for receiving a power supply required for the electronic device from an external power supply, and an external power supply for detecting whether the external power supply is supplied from the external power supply means. Power supply from the external power supply is detected by the external power supply detection means, and when the communication interface is connected while using the power of the external power supply, the power supply from the external power supply is performed. Power supply control means for continuously using the electric power. According to such a configuration, when the electronic device detects the power supply from the external power supply, the switching control of the power supply source can be performed so as to preferentially use the power supplied from the external power supply. .
[0012]
Further, the invention according to claim 5 further includes a power supply indicator for changing a presentation state in conjunction with switching of a current power supply source. According to such a configuration, since the source of the power consumed by the electronic device is presented, the user of the electronic device can check the source of the power.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Here, an electronic camera having a USB interface will be described as an example of an embodiment of the electronic apparatus.
[0014]
FIGS. 1A and 1B are block diagrams each showing a connection form of a USB interface system. As shown in FIG. 1A, in the USB interface system, a host device 2 such as a desktop PC or a notebook PC is connected to a USB hub 4 via a USB cable 3A, and a communication path is branched by the USB hub 4 to form a USB cable. The electronic camera 1 and other USB peripheral devices 5 are connected through 3B and 3C. At this time, the electronic camera 1 is an example of the USB peripheral device 5, and the USB peripheral device 5 including the electronic camera 1 is USB-connected to the host device 2 via the USB hub 4 so as to be able to perform data communication with each other. In FIG. 1A, the USB hub 4 is viewed from the electronic camera 1 and the USB peripheral device 5, and the direction of the host device 2 is referred to as the USB upstream side, and the USB hub 4 is viewed from the host device 2. The direction of the electronic camera 1 and the USB peripheral device 5 will be referred to as a USB downstream side and will be described below. As described above, in the USB interface system, the USB connection branches in the USB downstream direction, and a plurality of USB peripheral devices 5 are connected to the end thereof. The USB connections are merged and integrated into one connection in the host device 2. That is, there is only one host device 2 in one USB interface system. In the USB interface system of FIG. 1B, the electronic camera 1 is directly connected to the host device 2 via a USB cable 3D as a USB peripheral device, but there is only one host device 2 as described above.
[0015]
In the USB standard, the operation mode is classified into several USB device classes and defined according to the function type of the USB peripheral device 5. As an example of the USB device class, a USB device class that operates as an external storage device of the host device 2 is called a storage device class, and a USB device class that operates as an input device for still images and moving images is called an image device class. As described above, the electronic camera 1 USB-connected to the host device 2 performs mutual data communication with the host device 2 as a USB peripheral device 5 operating in one or more USB device classes defined by the USB standard. Upon receiving a USB command sent from only one host device 2 in the USB interface system, control, data processing, and data transfer corresponding to the USB command are performed. Further, power is supplied to the USB peripheral device 5 including the electronic camera 1 on the USB downstream side from the host device 2 and the USB hub 4 on the USB upstream side via the USB cable 3. This power is referred to as USB bus power.
[0016]
FIG. 2 is a block diagram illustrating a configuration of power supply of the electronic camera 1. As shown in FIG. 2, the electronic camera 1 includes a self-power source 6 including a primary battery, a rechargeable secondary battery, and the like for supplying power required for the operation of the electronic camera 1 therein. An external power supply 7 such as an AC adapter receives supply of AC power from a household AC power supply 8 to perform voltage conversion and rectification smoothing processing, and supplies DC power to the electronic camera 1 through an external power supply terminal unit 9. . This power is called external power. Further, the electronic camera 1 is provided with a USB terminal section 10 for performing the above-mentioned USB connection. When the USB connection is made, the USB bus power is supplied from a USB bus power supply source 11 such as the host device 2 or the USB hub 4 to the USB cable 3E. Is supplied to the USB terminal unit 10 through the USB port. The power supplied from the USB bus power supply source 11 is defined by the USB standard in a voltage range (minimum 4.65 V to maximum 5.25 V) and an upper limit current value of 100 mA. In the configuration by the software processing of the connection, when an increase request of the upper limit current value is issued from the USB peripheral device 5 side, the increase supply of the upper limit current value is performed according to the power supply capability of the USB bus power supply source 11.
[0017]
FIG. 3 is a block diagram illustrating a configuration of the electronic camera 1. The illustrated electronic camera 1 is divided into an electronic camera circuit unit 32 and a power supply unit 33 that supplies power to the entire electronic camera 1. The electronic camera circuit unit 32 includes a lens unit 20 for forming an image of a subject, an imaging unit 21 having an RGB color CCD and generating an image signal of the subject, and an image signal processing unit 22 for performing a color conversion process and a filter process on the image signal. A control unit 23 for controlling the entire electronic camera 1 which will be described in detail later; a program memory 24 for storing programs and data for controlling the electronic camera 1; Work memory 25 for convenience in processing, external storage medium 26 for storing captured image signals as image files, image compression / decompression unit 27 for performing data compression / decompression processing of image signals, composition confirmation and reproduction during shooting A display unit 28 for displaying an image, a power ON / OFF key, a shutter key, a mode key, an up cursor key, and a down cursor key (not shown) A key input unit 29 for providing instructions and settings for controlling the electronic camera 1; a USB transmission / reception for performing data communication for outputting data stored in the external storage medium 26 to the outside via the USB interface or taking in data from the outside; The unit 30 is configured to exchange signals via a data bus 31 which is a path for transferring data such as image signals and control signals. On the other hand, the power supply unit 33 includes an external power supply terminal unit 9 that receives power supply from the connected external power supply 7, a USB terminal unit 10 that receives a communication signal and power supply from the connected USB cable 3E, and power supply control and voltage conversion. And a power supply circuit unit 34 for performing the following. When the USB bus power is supplied in the USB standard voltage range in a state where the electronic camera 1 is connected to the USB, the electronic camera 1 needs to operate as a USB peripheral device of a storage class device and an image class device. It is assumed that the current value exceeds 100 mA.
[0018]
FIG. 4 is a memory map diagram of the program memory 24. The program memory 24 includes a program area 24a for storing a processing program executed for controlling the electronic camera 1 and performing data processing, and a data area 24b for storing data necessary for performing the control and the data processing. Then, in the data area 24b, a current value required to operate in an image device mode, which will be described in detail later, is stored as a "required current value in the image device mode". When a small hard disk having a compact flash (registered trademark) memory size is inserted into the electronic camera 1 as the external storage medium 26, the necessary current value is stored as the "necessary current value of the storage device mode A". The current value required when the external storage medium 26 composed of an IC memory such as a flash memory is inserted in the storage device mode is stored as “the required current value of the storage device mode B”.
[0019]
Here, the power ON / OFF operation of the electronic camera 1 will be described, supplementing the description of the configuration of the control unit 23 that controls the entire electronic camera. The control unit 23 includes a main CPU (Central Processing Unit) (not shown), a sub CPU that controls the power supply unit 33 and the key input unit 29, and an I / O controller that inputs and outputs various signals to and from the power supply circuit unit 34. The main CPU executes a processing program stored in advance in the program memory 24 to perform various controls and data processing. The sub CPU has a non-volatile memory therein and has a processing program therein, and is always supplied with power from the power supply unit 33 irrespective of the power ON / OFF state of the electronic camera 1 and the main CPU is stopped. The control of the power supply unit 33 and the key input unit 29 which also require control is performed. Therefore, when the power ON / OFF key is input from the key input unit when the power of the electronic camera 1 is OFF, the sub CPU detects the input of the power ON / OFF key and controls the power supply unit 33 to control the electronic power. The power of the camera 1 is turned on. As a result, control by the main CPU is started, and the entire electronic camera 1 starts operating. When the power ON / OFF key is input from the power ON state of the electronic camera 1, the sub CPU detects the input of the power ON / OFF key and controls the power supply unit 33 to turn off the power of the electronic camera 1. . Thereby, the main CPU stops the operation, and the electronic camera 1 ends the operation of the electronic camera 1 except for the sub CPU, the key input unit 29, the power supply unit 33, and the like.
[0020]
Hereinafter, the operation of each of the above-described components will be described as an example of an image recording operation and an image reproducing operation. First, an image recording operation will be described. When the electronic camera 1 is not connected to the USB and the power is on and a mode key (not shown) of the key input unit 29 is set to “recording mode”, the control unit 23 executes a recording mode processing program to execute a still image processing. It operates in a recording mode for performing moving image capturing and storage processing. First, the lens unit 20 is controlled by the control unit 23 to form a subject image on the light receiving surface of the RGB color CCD of the imaging unit 21. Then, the control unit 23 instructs generation of an image capturing signal at a periodic interval such as 1/30 second. The image capturing signal is generated by the imaging unit 21 and given to the RGB color CCD. , And further converted into an RGB image signal composed of a digital electric signal, and sent to the image signal processing unit 22. The image signal processing unit 22 converts the RGB image signal into an image signal (hereinafter, referred to as a YUV image signal) including a luminance signal and a color difference signal, and further performs digital image signal processing such as white balance adjustment and gamma correction. The YUV image signal is stored in the work memory 25.
[0021]
The YUV image signal for one screen (referred to as one frame) stored in the work memory 25 in this way is sent to the display unit 28, and the image of the subject is displayed. Then, the one-frame YUV image signal stored in the work memory 25 is replaced with the next one-frame YUV image signal newly imaged at a periodic interval such as 1/30 second. The images of the subject are sequentially displayed on the display unit 28 in synchronization with the switching, so that the moving image in the shooting standby state in the recording mode is displayed. This moving image is called a REC through moving image. Further, luminance information and white balance information are extracted from the YUV image signal stored in the work memory 25, and are used for control such as exposure adjustment and white balance automatic adjustment in the imaging process.
[0022]
In the shooting standby state of the recording mode, when a shutter key (not shown) of the key input unit 29 is input, the control unit 23 controls the lens unit 20 to perform an automatic exposure adjustment and an auto focus process, and the control unit 23 The image capturing unit 21 is instructed to generate an image capturing signal, and the image capturing signal is generated by the image capturing unit 21 and input to the RGB color CCD, so that an image capturing process of the subject is performed based on the timing at which the shutter key is input. Done. The YUV image signal obtained through the imaging unit 21 and the image signal processing unit 22 is stored in the work memory 25. When all the YUV image signals for one frame are stored in the work memory 25, the YUV image signals are sent to the image compression / expansion unit 27, and compressed by the image compression / expansion unit 27 in a JPEG (jointphotographic expertsgroup) format or the like. Is converted into image code data. This image code data is transferred to the external storage medium 26 and stored as an image file, and the imaging process is completed.
[0023]
Next, an image reproducing operation will be described. When the electronic camera 1 is not connected by USB and the power key is turned on and a mode key (not shown) of the key input unit 29 is set to “playback mode”, the control unit 23 executes the processing program of the playback mode and stores the program. It operates in a reproduction mode for reproducing and displaying still and moving images. First, the first image file is stored in the work memory 25 as image code data in accordance with the sequence number (for example, a photographing sequence number) assigned to the image file stored in the external storage medium 26. Is read. The image code data stored in the work memory 25 is expanded by the image compression / expansion unit 27 and expanded into a YUV image signal. The expanded YUV image signal is sent to the display unit 28 to display an image of the subject. In this state, when the input of the down cursor key or the up cursor key (not shown) is detected, the same processing as the above-described reproduction processing is performed on the second image and the last image file, and the image is displayed on the display unit 28. Are displayed sequentially.
[0024]
Next, an operation mode when the electronic camera 1 is connected by USB will be described. When the electronic camera 1 is connected via USB, the electronic camera 1 operates as a USB peripheral device in different operation modes corresponding to the recording mode and the playback mode, which are the operation modes of the electronic camera 1 not connected via USB. When the electronic camera 1 is connected by USB in the recording mode, the electronic camera 1 operates as an image device class USB peripheral device that transmits the above-described REC through moving image as image data to the host device 2 in real time, and is connected by USB in the reproduction mode. In this case, it operates as a storage device class USB peripheral device, which is an external storage device that stores an image file as viewed from the host device 2. An operation mode in which the host device 2 operates as a moving image input device in the image device class is referred to as an image device mode, and an operation mode in which the host device 2 operates as an external storage device in the storage device class is referred to as a storage device mode.
[0025]
FIG. 5 is a block diagram illustrating the configuration of a power supply path to the power supply unit 33 and the electronic camera circuit unit 32 of the electronic camera 1 in detail. The power of the battery 41, which is the self-power supply of the electronic camera 1, is input to the selector 42. External power is input from the external power supply terminal unit 9. This external power is input to the selector 42 through a voltage value detection circuit 45 that detects the input of power by a voltage value. The USB terminal section 10 includes a power supply positive terminal 44, a data plus signal terminal 45, a data minus signal terminal 46, and a power supply minus terminal 47. The power supply plus terminal 44 is a plus pole, and the power minus terminal 45 is a minus pole. USB bus power of a specified voltage value and current value is supplied. The USB bus power is input to the selector 42 through a voltage value detection circuit 51 for detecting power input and a current value detection circuit 49 for detecting a current value flowing into the electronic camera 1 from the USB bus power supply source 11. On the other hand, the data plus signal terminal 45 and the data minus signal terminal 46 are connected to the transceiver plus signal terminal 58 and the transceiver minus signal terminal 59 of the USB transceiver 30 respectively.
[0026]
Then, the power supply control circuit 50 detects a power supply control signal output from the control signal output terminal 51 of the electronic camera circuit section 32 by a predetermined setting by the circuit, software processing of a USB connection described later, and the supply of external power. The selection signal is determined based on the detection signal output from the voltage value detection circuit 43 and the current value detection circuit 49, and the selection signal is output to the selector 42. The selector 42 selects a power supply source from any one of the power of the battery 41, the external power, and the USB bus power according to the selection signal input from the power supply control circuit 50, and outputs the power to the voltage conversion circuit 52. I have. The voltage conversion circuit 52 converts the voltage value of the input power into a voltage value required by the electronic camera circuit unit 32 and outputs the voltage value to a power input terminal 53 of the electronic camera circuit unit 32. When the input of external power is detected by the voltage value detection circuit 43, a detection signal is input to the power supply control circuit 50. When the input of the external power is detected as described above, the power supply control circuit 50 outputs a selection signal for selecting the external power to the selector 42. Therefore, when external power is input, control is performed so that the external power is always used with priority.
[0027]
The indicator circuit 54 includes a red LED 55, a green LED 56, and an orange LED 57. The state in which the power supplied from the battery 41 is used as the power for operating the electronic camera 1 is the lighting of the red LED 55, and the state in which the power supplied from the external power is used is the lighting of the green LED 56. The state in which the power supplied from the USB bus power is used is the lighting of the orange LED 57, and the control signal is transmitted from the power supply control circuit 50 to the indicator circuit 54 in conjunction with the selection signal to the selector 42 as shown, respectively. Is output. As a result, one of the LEDs of the indicator circuit 54 is turned on to indicate the power supply source during operation of the electronic camera 1. When a voltage value specified by the USB standard is detected by the voltage value detection circuit 51 based on the input of the USB bus power supplied from the USB terminal unit 10, the USB power detection signal is input to the electronic camera circuit unit 32. The data is output to the terminal 60, and software processing for USB connection described later is started.
[0028]
The power control operation of the electronic camera 1 configured as described above will be described. First, the order in which the power of the electronic camera 1 is turned on and the connection to the host device 2 via the USB cable 3D and the operation thereof will be described. When the electronic camera 1 is connected to the host device 2 via the USB cable 3D while the power of the electronic camera 1 is turned off, and then the power ON / OFF key of the electronic camera 1 is input and the electronic camera 1 is started, the electronic camera circuit unit The voltage value detected by the voltage value detection circuit 48 is input to the voltage value input terminal 60 of the digital camera 32. As described above, the power consumption of the electronic camera 1 is equal to the current value supplied from the USB bus power in this state. Since the power exceeds the upper limit of 100 mA, the USB bus power cannot be used, and the USB bus power or the external power is used to start the USB bus power, and start a USB connection software process described in detail later.
[0029]
Next, an operation when the electronic camera 1 is connected to the host device 2 via a USB cable while the power of the electronic camera 1 is ON will be described. At this time, the voltage value detected by the voltage value detection circuit 48 is input to the voltage value input terminal 60 of the electronic camera circuit unit 32, and the power consumption of the electronic camera 1 is supplied from the USB bus power in this state. Since the current value exceeds the upper limit of 100 mA, the USB bus power cannot be used, and the power of the battery 41 or the external power is continuously used, and the USB connection software processing, which will be described in detail later, is started. As described above, when the input of the external power is detected, the external power is preferentially used, and when the input of the external power is not detected, the electronic camera 1 starts using the power of the battery 41. Then, the following power control processing is performed in accordance with the USB connection software processing.
[0030]
FIG. 6 is a diagram showing the flow of the USB connection software processing. When the electronic camera 1 is connected to the host device 2 via the USB cable 3D (or may be connected to the host device 2 via the USB hub 4), the voltage value detection circuit 48 detects the voltage value of the USB bus power. The detected signal is input to a voltage value input terminal 60 of the electronic camera circuit unit 32. As a result, the control unit 23 of the electronic camera 1 detects the connection with the host device 2 via the USB cable 3D, and starts software processing of the USB connection.
[0031]
The power-off electronic camera 1 is connected to the host device 2 via the USB cable 3D, and a power ON / OFF key (not shown) of the electronic camera 1 is input in the playback mode, or the electronic camera 1 operates in the playback mode. The operation when the USB cable 3D is connected to the host device 2 during the operation is described. As described above, the operation when the external power is supplied is given priority over the external power and is continuously used. First, in step S11, it waits for a reset command to be sent from the host device 2, and when the reset command is received, it is determined Yes in step S11 and the process proceeds to step S12, and in step S12, the host device 2 follows a prescribed procedure. The USB device address is set between the steps and the process proceeds to step S13. In step S13, the process waits for a configuration request from the host device 2, and when the configuration request is received, the determination in step S13 is Yes and the process proceeds to step S14. In step S14, the operation mode of the electronic camera 1 is checked. In this example, the electronic camera 1 is activated in the playback mode, but this playback mode is associated with a storage device mode operating as an external storage device of the host device 2. Further, the type of the external storage medium 26 inserted into the electronic camera 1 is also checked, and the process proceeds to step S15. In step S15, the necessary current value of the mode corresponding to the check result in step S14 is read from the respective necessary current values stored in the data area 24b.
[0032]
For example, a current value required by a compact hard disk having a compact flash (registered trademark) memory size as the external storage medium 26 is a current value required by a compact flash (registered trademark) memory configured by an IC memory even if the hard disk has the same shape. Is different from the value. Here, it is assumed that a small hard disk of a flash memory size is inserted as the external storage medium 26, and a current value of 450 mA is read as a necessary current value. When the necessary current value is read in this way, the process proceeds to step S16. In step S16, a necessary current value of 450 mA is inserted into the configuration data indicating the specification as a USB peripheral device to the host device 2 as a request for increasing the supply of USB bus power, and is transmitted to the host device 2. Proceed to S17. In step S17, the process waits for a configuration setting to be sent from the host device 2. When the configuration setting is received, the determination is Yes in step S17 and the process proceeds to step S18. In step S18, the configuration setting is sent from the host device 2. The current value supplied by the USB bus power in the configuration settings is read, and if the current value is less than the increased current value of 450 mA, it is determined as No in step S18, and the flow of the USB connection process ends. The host device 2 operates in the storage device mode as a USB peripheral device while continuing to use the power of the battery 41 as it is. On the other hand, if the current value in step S18 is 450 mA or more, which is the current value requested to increase, it is determined as Yes in step S18, and the process proceeds to step S19.
[0033]
In step S19, a control signal for switching the power usage from the power of the battery 41 to the USB bus power and a signal indicating the upper limit current value of the USB bus power set in the above-described configuration are sent to the control signal output terminal 51 via the I / O controller. It is output to the power supply control circuit 50. As a result, the power supply control circuit 50 outputs a selection signal for selecting the USB bus power to the selector 42, and the selected USB bus power is converted by the voltage conversion circuit 52 to a voltage required by the electronic camera circuit 32, and The power is supplied to the power input terminal 53 of the circuit 32. The power supply control circuit 50 outputs a control signal to the indicator circuit 54 in conjunction with the selection signal to the selector 42, turns on the orange LED 56 indicating the use of the USB bus power, and turns on the red LED indicating the use of the battery 41 power. Turn off the light. In this way, the power usage is switched from the battery 41 to the USB bus power, and the host device 2 operates in the storage device mode as a USB peripheral device. When the switching of the USB bus power to the power use is performed, the current value detection circuit 49 always detects the current value supplied from the USB bus power and outputs the detected current value to the power supply control circuit 50. The power supply control circuit 50 compares the signal indicating the upper limit current value of the USB bus power output from the electronic camera circuit unit 32 with the signal indicating that the supplied current value exceeds the upper limit value. By outputting a selection signal for switching to 41 and switching the power supply source to the battery 41, control is performed so as not to exceed the upper limit current value of the USB bus power.
[0034]
Next, the electronic camera 1 whose power is turned off is connected to the host device 2 with the USB cable 3D, and the power ON / OFF key of the electronic camera 1 is input in the recording mode, or the electronic camera 1 operates in the recording mode. The operation when the USB cable 3D is connected to the host device 2 during the operation is described. As described above, the operation when the external power is supplied is given priority over the external power and is continuously used. The operations from Step S11 to Step S13 are the same as those in the reproduction mode, and thus the description thereof will be omitted, and the description will be continued from Step S14. In step S14, the operation mode of the electronic camera 1 is checked. In this example, since the electronic camera 1 is activated in the recording mode, the image device mode for transmitting the REC through moving image to the host device 2 in real time is set as the USB device mode corresponding to the recording mode, and the process proceeds to step S15. In step S15, a required current value corresponding to the USB device mode set in step S14 is read from among the required current values stored in advance in the data area 24b according to the type of the USB device mode. For example, it is assumed that a current value of 300 mA is read as a required current value required in the image device mode. When the necessary current value is read in this way, the process proceeds to step S16.
[0035]
In step S16, the required current value of 300 mA is inserted into the configuration data indicating the specification as a USB peripheral device for the host device 2 as a request for increasing the supply of USB bus power, and is transmitted to the host device 2. In step S17, the process waits for a configuration setting to be sent from the host device 2. When the configuration setting is received, the determination is Yes in step S17 and the process proceeds to step S18. In step S18, the configuration setting is sent from the host device 2. The current value supplied by the USB bus power in the configuration settings is read out. If the current value is less than the increased current value of 300 mA, it is determined as No in step S18, and the flow of the USB connection process ends. , The power use of the battery 41 is continued as it is Operating in an image device mode as a USB peripheral winding devices 2. On the other hand, if the current value in step S18 is 300 mA or more, which is the current value for which the increase was requested, it is determined as Yes in step S18 and the process proceeds to step S19. A control signal for switching power usage from the power of the battery 41 to the USB bus power and a signal indicating the upper limit current value of the USB bus power set in the configuration are output to the power supply control circuit 50. As a result, the power use is switched from the battery 41 to the USB bus power, and the host device 2 operates in the image device mode as a USB peripheral device.
[0036]
When the electronic camera 1 is connected to the host device 2 via USB and operates in the storage device mode or the image device mode, the USB cable 3D is pulled out or the power ON / OFF key of the electronic camera 1 is input. In this case, the electronic camera 1 ends the operation of the host device 2 as a USB peripheral device and is turned off.
[0037]
As described above, even if the electronic camera 1 operates within the current value of 100 mA or less and cannot perform the USB connection configuration, the electronic camera 1 is activated by its own power supply and performs the USB connection configuration processing. , By increasing the supply of USB bus power from the host device 2 or the USB hub 4 connected to the USB, and then switching the power consumption to use the USB bus power, thereby effectively utilizing the power supplied by the USB bus. As a result, the power consumption of the self-power supply of the electronic device can be suppressed and the remaining amount of the battery can be preserved. In the above embodiment, an example in which the present invention is applied to the electronic camera 1 has been described. However, the present invention is not limited to this, and may be applied to an electronic device such as a PDA (Personal Digital Assistant). Further, the communication interface system for supplying power via the communication cable has been described using the USB interface as an example, but is not limited thereto, and may be applied to other communication interface systems.
[0038]
【The invention's effect】
As described in detail in the embodiments above, according to the electronic apparatus of the present invention, when the requested power is supplied from the power supply source supplied via the communication interface, the power consumption is reduced from the own power supply to the communication interface. By switching to the use of the electric power supplied via the electronic device, the power consumption of the self-power supply of the electronic device can be suppressed and the remaining amount of the battery can be preserved.
[Brief description of the drawings]
FIG. 1 (A) and (B)
FIG. 2 is a block diagram showing a configuration of a USB interface system.
FIG. 2 is a block diagram showing a configuration of a power supply system of the electronic camera 1.
FIG. 3 is a block diagram mainly illustrating a configuration of an electronic camera circuit unit 32 of the electronic camera 1;
FIG. 4 is a memory map diagram of a program memory 24 of the electronic camera 1;
FIG. 5 is a block diagram mainly illustrating a configuration of a power supply unit 33 of the electronic camera 1.
FIG. 6 is a flowchart showing USB connection software processing executed by the electronic camera 1.
[Explanation of symbols]
1 electronic camera
2 Host device
3A to 3E USB cable
4 USB hub
5 USB peripheral devices
6 Self power
7 External power supply
8 Household AC power supply
9 External power supply terminal
10 USB terminal
20 lens section
21 Imaging unit
22 Image signal processing unit
23 Control unit
24 Program memory
25 Work memory
26 External storage media
27 Image compression / decompression unit
28 Display
29 Key input section
30 USB transceiver
31 Data bus
32 Electronic camera circuit
33 Power supply section
34 Power supply circuit
41 batteries
42 Selector
43 Voltage detection circuit
44 Power supply positive terminal
45 Data plus terminal
46 Data minus terminal
47 Power minus terminal
48 Voltage detection circuit
49 Current value detection circuit
50 Power supply control circuit
51 Control signal output terminal
52 voltage conversion circuit
53 Power input terminal
54 Indicator Circuit
55 red LED
56 green LED
57 orange LED
58 Transmitter / receiver plus signal terminal
59 Transceiver negative signal terminal
60 Voltage input terminal

Claims (7)

The electronic device connected to a host device including a power supply unit that supplies power to the electronic device connected via a communication interface,
This electronic device
Self-power supply means operated by power from its own power supply means,
Requesting means for requesting the host device to request power for maximizing a current value larger than the predetermined current value after being activated by the self-power supply means;
When power that maximizes a current value greater than the predetermined current value is supplied from the host device by the request unit, the power for the operation is changed from the power of the self-power supply unit to the host device. Switching means for switching to power of
An electronic device comprising: A first power supply unit for supplying power that maximizes a predetermined current value to an electronic device connected via a communication interface, and a current larger than the predetermined current value in response to a request from the electronic device. The electronic device connected to a host device including a second power supply unit that supplies power to maximize the value to the electronic device,
This electronic device
Self-power supply means for self-supplying power necessary to operate the electronic device,
When the current value required when connected to the communication interface while operating using the power of the self-power supply means exceeds the predetermined current value, the host device sets the predetermined current value. Requesting means for requesting power to maximize a current value larger than the current value
When power that maximizes a current value greater than the predetermined current value is supplied from the host device by the request unit, the power for the operation is changed from the power of the self-power supply unit to the host device. Switching means for switching to power of
An electronic device comprising: Power consumption storage means for storing maximum power consumption data for each operation mode of the electronic device;
Data reading means for reading the maximum power consumption data in the current operation mode from the power consumption storage means,
2. The device according to claim 1, wherein the requesting unit includes a request determining unit that determines a current value required for the host device based on the maximum power consumption data in the current operation mode read by the reading unit. Or the electronic device according to 2. Further, external power input means for receiving power supply required for the electronic device from an external power source,
External power detection means for detecting whether external power is supplied from the external power input means,
The power supply from the external power supply is detected by the external power supply detection means, and when the communication interface is connected in a state where the power of the external power supply is used, the power supply that continues to use the power supplied from the external power supply The electronic device according to claim 1, further comprising a control unit. The electronic device according to claim 1, further comprising a power supply indicator that changes a presentation state in conjunction with switching of a current power supply source. A power supply control method for the electronic device connected to a host device including a power supply unit that supplies power to the electronic device connected via a communication interface,
Operating with power from its own power supply means;
Requesting power to maximize the current value larger than the predetermined current value to the host device after being activated by the self-power supply step;
A step of switching the power for the operation to the power from the host device when a power that maximizes a current value larger than the predetermined current value is supplied from the host device by the requesting process,
A power supply control method for an electronic device, comprising: A power supply control program for the electronic device connected to a host device including a power supply unit that supplies power to the electronic device connected via a communication interface,
Operate the electronic device with power from its own power supply means,
Requesting power to maximize a current value larger than the predetermined current value to the host device after being activated by power from its own power supply means,
When power that maximizes a current value larger than the predetermined current value is supplied from the host device by this request, the power for the operation is changed from the power of the self power supply unit to the power from the host device. A power supply control program for an electronic device, characterized by switching to electric power.

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