JP2006185288A - Data communication apparatus, and logical connection disconnection method for its communication path - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data transfer device for improving user's operability by inputting a disconnection instruction when the user desires to disconnect logical connection of a communication path even during file access and preventing a file from being destructively deleted, damaged and the like by suspending a disconnection operation during file access, and to provide a logical connection disconnection method for its communication path. <P>SOLUTION: When a disconnection instruction is inputted by a touch panel 46 during data transfer based on a file access instruction, a system control microcomputer 51 suspends the disconnection instruction, and when the data transfer based on the file access instruction is finished while the disconnection instruction is suspended, the suspension of the disconnection instruction is released to disconnect the logical connection of the communication path. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data communication apparatus in which data stored in a storage medium is accessed by a host apparatus in which a logical connection of a communication path is established, and a method of disconnecting the logical connection of the communication path.

  In recent years, a USB interface has become widespread as an interface for connecting a personal computer (hereinafter referred to as a PC) and a PC peripheral device. The USB interface was originally used for low-speed devices such as keyboards and mice, but was upgraded to USB specification 2.0 and mass storage devices such as HDD (Hard Disk Drive) and optical disk devices, printers, scanners, etc. Are widely used in audio-visual (AV) devices such as digital input / output devices and digital cameras.

  Some USB peripheral devices perform an operation for safely removing a USB cable by a USB host device, and others perform an operation for safely removing a USB cable by a USB peripheral device. This operation means disconnection of the logical connection of the USB interface. An example of a USB peripheral device that disconnects the logical connection of the USB interface on the peripheral device side is a digital camera. In a conventional USB-compatible digital camera, the USB interface is logically disconnected by inputting a disconnection command using the operation button of the camera body or a touch panel integrally formed with the liquid crystal panel, and then the USB cable is secured from the camera. Had been removed.

However, in the conventional USB-compatible digital camera, when the disconnection command is input, the logical connection of the USB interface is immediately disconnected regardless of the file access from the USB host device, so that the data being transferred is destroyed. There was a case.
Therefore, in a conventional USB-compatible digital camera that monitors file access from a USB host device, the disconnect operation is prohibited during file access, and the prohibition of the disconnect operation is canceled after the file access is completed.

FIG. 9 is a diagram illustrating an example of a method for disconnecting a communication path of a conventional USB-compatible digital camera.
As shown in FIG. 9, in this digital camera, when the file write command (W1) from the USB host device is received, the disconnection operation is prohibited, the timer is reset, and the countdown is started. If the file write command (W2) is received before the count value of the timer becomes “0”, the timer is reset again, thereby extending the prohibition of the cutting operation. When the count value becomes “0”, it is determined that the execution of a series of data file write commands is completed, and the prohibition of the cutting operation is released.
When the file write command is received in this way, the disconnection operation is prohibited, so that data loss, destruction, etc. as described above are prevented.

As described above, a file server device disclosed in Patent Document 1 is disclosed as a device that disconnects a logical connection between a peripheral device and a PC.
In this file server apparatus, a bypass path for power control by the automatic switch 20 is set during a period accessed by the PC. After the bypass path is set, when the power switch is input by the manual switch 21, the power switch is suspended by the automatic switch 20, and when the file operation is completed, the power is turned off by the automatic switch 20.
Japanese Patent Laid-Open No. 1-25117

However, although the file server apparatus of the above-mentioned patent document 1 cuts off the power supply, there is no description about the disconnection of the logical connection.
In addition, in the conventional USB-compatible digital camera in which the disconnection operation is prohibited as described above, the user must perform the disconnection operation after confirming the end of the file access by a message displayed on the liquid crystal panel or the like. In other words, the operator felt that the operation was difficult when the user wanted to cut.

  The present invention has been made in view of such circumstances, and an object of the present invention is to input a disconnection instruction when the user wants to disconnect the logical connection of the communication path even during file access, and to operate the user. Another object of the present invention is to provide a data transfer apparatus and a method for disconnecting a logical connection of a communication path of the data transfer apparatus, which prevent the file from being lost and destroyed by holding the disconnection operation during file access.

In order to achieve the above object, the data communication apparatus of the present invention establishes a logical connection of a communication path between a storage means for storing data and a host apparatus, and then stores the storage in accordance with a file read command from the host apparatus. Reading data stored in the means, transferring the read data to the host device through the communication path, and transferring the data transferred from the host device through the communication path in accordance with a file write command from the host device. Control means for writing to the storage means; and input means for inputting a disconnection command for disconnecting the logical connection of the communication path established by the control means, wherein the control means includes the disconnection command input by the input means According to the data transfer device for disconnecting the logical connection of the communication path according to the control unit, the control means When the disconnection command is input by the input means during the transfer of data based on the output command or the file write command, the disconnect command is suspended, and the file read command or the file write command is suspended while the disconnect command is pending When the data transfer based on the above is completed, the disconnection of the disconnection command is canceled and the logical connection of the communication path is disconnected.
Further, according to the data transfer device logical connection disconnection method of the present invention, the data stored in the storage means is read and transferred to the host device in accordance with the file read command from the host device, and from the host device. A method of disconnecting a logical connection of a data transfer device, which disconnects a logical connection of a communication path established with the host device so as to write data transferred from the host device to the storage means in accordance with a file write command. An input step of inputting a disconnection command for disconnecting the logical connection of the communication path; and a disconnection step of disconnecting the logical connection of the communication path according to the disconnection command input in the input step, the disconnection step comprising: The input step is performed during data transfer based on the file read command or the file write command. When the disconnect command is input, the disconnect command is suspended, and when the transfer of data based on the file read command or the file write command is completed while the disconnect command is pending, the disconnect command is released. Then, the logical connection of the communication path is disconnected.

According to the present invention, when the disconnect command is input in the input step during the transfer of data based on the file read command or the file write command, the disconnect command is suspended and the disconnect command is suspended. When the data transfer based on the file read command or the file write command is completed, the disconnection command is released and the logical connection of the communication path is disconnected.
Therefore, even when the file is being accessed, the disconnection command can be input when the user wants to disconnect, so that the operability for the user can be improved. In addition, since the disconnection operation is suspended during file access, data loss and destruction can be prevented.

In order to achieve the above object, the data transfer apparatus includes storage means, input means, and control means.
The storage means stores data. The input means inputs a disconnection command for disconnecting the logical connection of the communication path with the host device.
The control means establishes the logical connection of the communication path with the host device, and then reads the data stored in the storage means in accordance with the file read command from the host device, and reads the read data to the host device through the communication path. In addition to the transfer, the data transferred from the host device through the communication path is written to the storage means in accordance with a file write command from the host device.
The control unit holds the disconnection command when the disconnection command is input by the input unit during data transfer based on the file read command or the file write command, and the file read command or the file while the disconnection command is held. When the data transfer based on the write command is completed, the suspension of the disconnect command is released and the logical connection of the communication path is disconnected. Further, the control unit ignores the file read command or the file write command from the host device after starting to release the suspension of the disconnect command and does not accept it.

Hereinafter, a data transfer apparatus and a method for disconnecting a logical connection of a communication path according to the present invention will be described with reference to the drawings.
In the first embodiment, a digital camera to which the data transfer apparatus of the present invention is applied will be described as an example.
FIG. 1 is a diagram illustrating a connection state of the digital camera according to the first embodiment.
As shown in FIG. 1, the digital camera 20 is connected to the host PC 10 via a USB cable 30. The host PC 10 is a USB host device, and the digital camera 20 is a USB peripheral device. The digital camera 20 selectively switches between two types of device classes, for example, a mass storage class and an imaging class (PictBridge), and performs communication with the host PC. The host device in the imaging class is not a PC 10 but a printer.

FIG. 2 is a diagram showing the configuration of the USB cable 30 shown in FIG.
As shown in FIG. 2, the USB cable 30 includes an A plug 31 connected to the host PC 10 and a B plug 32 connected to the digital camera 20. The USB cable 30 includes four signal lines, that is, a VBUS signal line 30A, a D + signal line 30B, a D- signal line 30C, and a GND signal line.

FIG. 3 is a diagram illustrating a method for establishing a communication path.
When the host PC 10 and the digital camera 20 are physically connected via the USB cable 30, a 5V VBUS signal is supplied by the host PC 10 at time T1, and the host PC 10 is detected by the digital camera 20. Next, at time T2, the D + signal is pulled up to 3V by the digital camera 20, and the digital camera 20 is detected by the host PC 10. Next, at time T3, the host PC 10 returns the D + signal to 0 V, and resetting is performed. Next, at time T4, the reset of the D + signal is released by the host PC 10, thereby establishing a logical connection of the communication path between the host PC 10 and the digital camera 20.
On the other hand, when the logical connection of the communication path is disconnected, the pull-up of the D + signal is canceled by the digital camera 20, and the disconnection of the logical connection of the communication path is detected by the host PC 10 due to the timeout of the 0V D + signal.

FIG. 4 is a diagram showing the configuration of the digital camera 20 shown in FIG.
As shown in FIG. 4, the digital camera 20 includes a camera block 41, a memory card 42, a memory card controller 43, an LCD panel 44, an LCD panel controller 45, a touch panel 46, keys 47, a system control microcomputer 51, a RAM 52, a ROM 53, and a USB. A controller 54 is provided.

The camera block 41 includes a lens, a CCD sensor, a signal processing circuit, a Codec circuit, and the like (not shown), performs various image processing on image (moving image and still image) signals photographed by the CCD, and uses the image signal as a key 47. The image data is converted into image data of a format selected based on the input information input by (described later).
The memory card 42 stores an image taken by the CCD sensor of the camera block 41. The memory card controller 43 controls the operation of the memory card 42.
The LCD panel 44 displays an image taken by the CCD sensor and an image stored in the memory card 42, and also displays status information and setting information of the digital camera. The LCD panel controller 45 controls the operation of the LCD panel 44.
The touch panel 46 is configured integrally with the LCD panel 44 and inputs user operation information based on an operation screen displayed by the LCD panel 44. The key 47 is composed of operation keys, operation levers, and the like, and inputs user operation information.

The system control microcomputer 51 controls each part of the digital camera 20 based on the operation information input from the LCD panel 44 and the key 47. The RAM 52 is a working memory for the system control microcomputer 51. The ROM 53 stores a program executed by the system control microcomputer 51.
The USB controller 54 performs communication control with the host PC 10 connected via the communication cable 20 in cooperation with the system control microcomputer 51.

  In such a digital camera 20, the memory card 42 is accessed by the host PC 10. When a file read command is issued by the host PC 10, data is read from the memory card 42 by the system control microcomputer 51, and the read data is transmitted to the host PC 10 by the USB controller 54. On the other hand, when a file write command is issued by the host PC 10, data transmitted by the host PC 10 is received by the USB controller 54, and the received data is written to the memory card 42 by the system control microcomputer 51.

FIG. 5 is a diagram illustrating a communication path disconnection method when there is no file access.
As shown in FIG. 5, when the host PC 10 and the digital camera 20 are physically connected via the USB cable 30, the initial screen 60 of the liquid crystal panel 44 is switched to the USB connection screen 61. “Storage connected” is displayed, and an end button 62 for disconnecting the communication path is displayed in the upper right part thereof.
When the user touches the end button 62 on the touch panel 46 when there is no file access from the host PC 10 and a disconnect command is input thereby, the communication path is immediately disconnected by the system control microcomputer 51, and the liquid crystal panel 44 is initialized. The screen is switched to the screen 60.

FIG. 6 is a diagram illustrating a method for disconnecting a communication path during file access.
As shown in FIG. 6, when the host PC 10 and the digital camera 20 are physically connected via the USB cable 30, the initial screen 60 of the liquid crystal panel 44 is switched to the USB connection screen 61. “Storage connected” is displayed, and an end button 62 for disconnecting the communication path is displayed in the upper right part thereof.
When the end button 62 is touched by the user through the touch panel 46 during file access from the host PC 10 and a disconnection command is input, the disconnection operation of the communication path is suspended by the system control microcomputer 51, and the USB connection screen 61 is displayed. A standby message screen 63 is displayed over the top. The standby message screen 63 displays a message such as “Accessing from a personal computer. Please wait for a while”. Thereby, the operation state of the digital camera 20 is recognized by the user.
When the file access from the host PC 10 ends, the system control microcomputer 51 cancels the suspension of the communication path disconnection operation, the communication path is disconnected, and at the same time, the USB connection screen 61 and the standby message screen 63 of the liquid crystal panel 44. Is switched to the initial screen.

FIG. 7 is a diagram illustrating a communication path disconnection sequence.
As shown in FIG. 7, the system control microcomputer 51 resets the count value of the timer every time a file write command (or file read command) is received from the host PC 10, and the host PC 10 sends a series of data to the file write command. Counts the time that exceeds the time required for access (hereinafter referred to as disconnection prohibition time).
The disconnection prohibition time is the time of the file write command before and after, but this time is variable and varies depending on the model of the USB host device, so that an optimal time can be obtained by experiment.

First, when a file write command (W1) is received from the host PC 10, the timer is reset by the system control microcomputer 51, and the count value starts down-counting.
When a communication path disconnection command is input from the touch panel 46 during reception of write data from the host PC 10, that is, during file access, the count value of the timer is detected by the system control microcomputer 51. This detection is repeated for each detection time shorter than the disconnection prohibition time until the count value of the timer becomes “0”. The optimum detection time is also determined by experiment.
When the count value of the detected timer is not “0”, it is determined that the file is being accessed, and the system control microcomputer 51 suspends execution of the communication path disconnection command.

Next, when a file write command (W2) is received from the host PC 10, the system control microcomputer 51 resets the timer and starts the count down of the count value. Thereby, the suspension of the disconnection command is extended.
The count value of the timer is detected every time the detection time elapses by the system control microcomputer 51. When the count value of the timer is “0”, it is determined that the file access is completed, and the disconnection command is suspended by the system control microcomputer 51. The communication path is disconnected.

FIG. 8 is a diagram showing a file access instruction rejection sequence.
As shown in FIG. 8, when the system control microcomputer 51 releases the communication path disconnection command and starts the disconnection operation, the system control microcomputer 51 receives the file write command (or file read command) from the host PC 10. Ignore the file write command and do not accept it. As a result, the reception of the file write command in a short time during the cutting operation is prevented, and the loss or destruction of the file is prevented.

As described above, according to the first embodiment, when a disconnection command is input from the touch panel 46 during the transfer of data based on the file access command, the disconnect command is suspended, and the data based on the file access command is suspended while the disconnect command is pending. When the transfer ends, the disconnection command is released and the logical connection of the communication path is disconnected.
Therefore, when the user wants to cut, a cutting command can be input, so that the operability for the user can be improved. In addition, since the disconnection operation is suspended during file access, data loss, destruction, and the like can be prevented.

Also, the count value of the timer is reset each time a file access command is detected, the disconnection prohibition time is counted by the timer, and when the disconnection prohibition time has elapsed, the disconnection command is released and the logical connection of the communication path Disconnect.
Therefore, it is possible to implement the hold of the disconnection command with a simple configuration using a timer.

Further, when the disconnection command is suspended, information indicating that the disconnection command is suspended is displayed on the liquid crystal panel 44.
Accordingly, it is possible to notify the user of the operation state of the digital camera 20 and prevent the operation of the touch panel 46 from being repeated as in the past, thereby eliminating the troublesome operation.

  Further, since the file access command from the host PC 10 is ignored and not accepted after the release of the hold of the disconnect command is started, it is possible to prevent data loss, destruction, and the like.

  In the first embodiment, the USB-compatible digital camera 20 has been described as an example. However, the data communication device of the present invention is not limited to a USB-compatible data communication device, and for example, a portable audio player or a mobile phone. Various devices such as are applied. The host device to which the data communication device of the present invention is connected is not limited to a PC, and various devices such as a printer, an optical disc recording / reproducing device, a hard disk recording / reproducing device, and a television receiver can be applied.

FIG. 3 is a diagram illustrating a connection state of the digital camera according to the first embodiment. It is a figure which shows the structure of the USB cable 30 shown by FIG. It is a figure which shows the establishment method of a communication path. It is a figure which shows the structure of the digital camera 20 shown by FIG. It is a figure which shows the cutting method of a communication path when there is no file access. It is a figure which shows the cutting method of the communication path in case of file access. It is a figure which shows the cutting sequence of a communication path. It is a figure which shows the command rejection sequence of a file access. It is a figure which shows an example of the cutting method of the communication path of the conventional digital camera corresponding to USB.

Explanation of symbols

  10 ... PC, 20 ... digital camera, 30 ... USB cable, 41 ... camera block, 42 ... memory card, 44 ... LCD panel, 47 ... USB controller, 51 ... system control microcomputer.

Claims (8)

Storage means for storing data;
After establishing the logical connection of the communication path with the host device, the data stored in the storage means is read in accordance with a file read command from the host device, and the read data is transferred to the host device through the communication path. Control means for writing data transferred from the host device through the communication path to the storage means in accordance with a file write command from the host device,
Input means for inputting a disconnection command for disconnecting the logical connection of the communication path established by the control means;
The control means is a data transfer device that disconnects the logical connection of the communication path in accordance with the disconnection instruction input by the input means,
The control unit holds the disconnection command when the input command is input by the input unit during data transfer based on the file read command or the file write command, and the file is stored while the disconnect command is held. When the transfer of data based on the read command or the file write command is completed, the suspension of the disconnect command is released and the logical connection of the communication path is disconnected.
A data transfer device. The control means includes
Each time the file read command or the file write command from the host device is detected, the count value is reset, and it is necessary for the host device to access a series of data by the file read command or the file write command. Has a timer that counts time exceeding the time,
2. The data transfer apparatus according to claim 1, wherein when the time counted by the timer is counted, the disconnection of the disconnection instruction is canceled and the logical connection of the communication path is disconnected. Having display means for displaying device information;
2. The data transfer apparatus according to claim 1, wherein when the disconnection command is suspended, the control unit causes the display unit to display information indicating that the disconnection command is suspended.   2. The data transfer device according to claim 1, wherein the control unit ignores the file read command or the file write command from the host device after starting to release the hold of the disconnection command, and does not accept the file read command. . According to a file read command from the host device, the data stored in the storage unit is read and transferred to the host device, and the data transferred from the host device is written to the storage unit according to the file write command from the host device. A method of disconnecting the logical connection of the data transfer device for disconnecting the logical connection of the communication path established with the host device,
An input step of inputting a disconnection command for disconnecting the logical connection of the communication path;
Disconnecting the logical connection of the communication path according to the disconnection command input in the input step,
The cutting step includes
When the disconnect command is input in the input step during data transfer based on the file read command or the file write command, the disconnect command is suspended, and the file read command or the file is suspended while the disconnect command is pending When the transfer of data based on the write command is completed, the suspension of the disconnect command is released and the logical connection of the communication path is disconnected.
A method for disconnecting a logical connection of a communication path of a data transfer apparatus. The cutting step includes
Each time the file read command or the file write command from the host device is detected, the timer count value is reset, and the host device accesses a series of data by the file read command or the file write command. Including a time measuring step of counting a time exceeding a required time by the timer,
6. The method for disconnecting a logical connection of a communication path in a data transfer apparatus according to claim 5, wherein when the timing step is completed, the disconnection of the disconnection command is canceled and the logical connection of the communication path is disconnected.   6. The communication path of the data transfer apparatus according to claim 5, further comprising a display step of displaying information indicating that the disconnection instruction is held when the disconnection instruction is held in the disconnection step. To disconnect the logical connection.   6. A command ignoring step of ignoring and not accepting the file read command or the file write command from the host device after release of the hold of the cut command is started in the disconnecting step. A method for disconnecting a logical connection of a communication path of the data transfer apparatus described.

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