JP2004110328A - Compound device and electric current distributing method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound device capable of avoiding a shortage of an electric current due to an overlap of periods increased in electric current consumption of each of a plurality of external memory devices, and to provide an electric current distributing method for the same. <P>SOLUTION: This compound device 50 is formed of a hub controller 51 connected to a computer 40 through a serial bus 42 and a plurality of external memory devices 52 and 53 connected to the computer 40 through the hub controller 51 to limit the electric current to be consumed in the plurality of external memory devices 52 and 53. One external memory device 53 of the plurality of external memory devices supplies an electric current consumption monitor signal to the other external memory device 52, and operation of the other external memory device 52 is limited so that the electric current consumption thereof is less than the predetermined value when the electric current consumption of the external memory device 53 increases on the basis of the electric current consumption monitor signal. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multifunction device and a current distribution method thereof, and more particularly to a multifunction device connected to a computer such as a personal computer via a hub controller and having a plurality of external storage devices and a current distribution method thereof.
[0002]
[Prior art]
FIG. 5 is a block diagram showing an example of a computer system using a conventional external storage device. A flexible disk device 20 is connected to a USB (Universal Serial Bus) interface 11 of the personal computer 10 via a USB 12 as an interface cable, and a flash card reader is connected to a USB interface 13 of the personal computer 10 via a USB 14 as an interface cable. / Writer 30 is connected. The flexible disk device 20 and the flash card reader / writer 30 are used as external storage devices of the personal computer 10.
[0003]
[Problems to be solved by the invention]
Conventionally, the flexible disk device 20 and the flash card reader / writer 30 are connected to the personal computer 10 via separate USBs 12 and 14, respectively. Therefore, it is necessary to prepare a plurality of USB interfaces 11 and 13 in the personal computer 10. .
[0004]
However, when the personal computer 10 is a notebook type, it is difficult to mount a plurality of USB interfaces. When the flexible disk device 20 and the flash card reader / writer 30 are simultaneously connected to the notebook personal computer 10 having only a single USB interface, it is necessary to prepare a USB hub and add ports.
[0005]
In this case, power for the flexible disk device 20 and the flash card reader / writer 30 is supplied from the personal computer 10 through a USB hub. The maximum current that the personal computer 10 can output from one USB interface is 500 mA, while the maximum current consumption of the flexible disk device 20 is 400 mA, and the maximum current consumption of the flash card reader / writer 30 is 200 mA. When the current consumption of the disk device 20 and the flash card reader / writer 30 simultaneously becomes the maximum, the personal computer 10 cannot supply the necessary current, and the flexible disk device 20 and the flash card reader / writer 30 can operate normally. There was a problem of disappearing.
[0006]
SUMMARY An advantage of some aspects of the invention is to provide a multifunction peripheral and a current distribution method capable of preventing a current shortage due to overlapping current consumption increase periods of a plurality of external storage devices. .
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, a hub controller (51) connected to a computer (40) via a serial bus (42) and a plurality of hub controllers (51) connected to the computer (40) via the hub controller (51). A multi-function device (50) comprising a plurality of external storage devices (52, 53), wherein the current consumed by the plurality of external storage devices (52, 53) is limited;
One of the external storage devices (53) supplies a current consumption monitor signal to the remaining external storage devices (52),
The remaining external storage device (52) limits the operation based on the current consumption monitor signal so that the current consumption becomes less than a predetermined value when the current consumption of the one external storage device (53) increases.
[0008]
According to a fourth aspect of the present invention, there is provided a hub controller (51) connected to a computer (40) via a serial bus (42), and a hub controller (51) connected to the computer (40) via the hub controller (51). A current distribution method for distributing a current consumed by the plurality of external storage devices (52, 53) in a composite device (50) including a plurality of external storage devices (52, 53),
Supplying a current consumption monitor signal from one external storage device (53) of the plurality of external storage devices to the remaining external storage devices (52);
When the current consumption of the one external storage device (53) increases, the current consumption of the remaining external storage device (52) is limited to be less than a predetermined value based on the current consumption monitor signal.
[0009]
In the present invention, in order to limit the current consumption of the remaining external storage devices (52) to less than a predetermined value based on the current consumption monitor signal supplied from one external storage device (53), a plurality of external storage devices are provided. It is possible to prevent the current consumption shortage due to the overlap of the current consumption increasing periods of the devices (53, 52).
[0010]
The reference numerals in the parentheses are provided for easy understanding, are merely examples, and are not limited to the illustrated embodiments.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing one embodiment of a computer system using the multifunction peripheral of the present invention. In the figure, a multi-function device 50 of the present invention is connected to a USB interface 41 of a personal computer 40 via a USB 42 as an interface cable. The multifunction device 50 includes a USB hub controller 51, a flash card reader / writer 52 as an external storage device, and a flexible disk device 53.
[0012]
The personal computer 40 assigns a unique address to the flash card reader / writer 52 and the flexible disk device 53 connected via the USB hub controller 51.
[0013]
The USB hub controller 51 is connected to the USB interface 41 of the personal computer 40 via the USB 42, receives a USB standard (serial communication standard) command (token packet) and data supplied from the personal computer 40, and includes the command. Either the flash card reader / writer 52 or the flexible disk device 53 responds to the personal computer 40 in accordance with the address to be read.
[0014]
The flash card reader / writer 52 operates in response to a command from the personal computer 40, and records / reproduces data in / from a flash memory as a storage medium. The flexible disk device 53 operates in response to a command from the personal computer 40 to record / reproduce data.
[0015]
Further, the flexible disk device 53 outputs a current consumption monitor signal which is at a low level during a period of increasing current consumption at the time of activation of a spindle motor for rotating and driving the flexible disk and at a time of head seek, and at a high level at other times. This current consumption monitor signal is supplied to the flash card reader / writer 52. When the current consumption monitor signal goes low, the flash card reader / writer 52 restricts (prohibits) writing.
[0016]
By the way, the flash card reader / writer 52 consumes 50 mA in the power saving mode, and has a maximum current consumption of 200 mA when writing data in the normal mode. In the flexible disk drive 53, the current consumption in the normal mode is 200 mA, and the maximum current consumption when the spindle motor is started and the head seeks in the normal mode are 400 mA.
[0017]
FIG. 2 shows a flowchart of the current consumption monitoring process executed by the flexible disk device 53. In step S10, the flexible disk device 53 sets the current consumption monitor signal to a high level and outputs it. Next, in step S12, it is determined whether or not a spindle motor start command has been received from the personal computer 40. If the spindle motor start command has been received, the flow advances to step S14 to set the current consumption monitor signal to low level for a predetermined time Ta. And the process proceeds to step S16. On the other hand, if the spindle motor start command has not been received in step S12, the process directly proceeds to step S16.
[0018]
The flexible disk device 53 starts the spindle motor after a time T1 from the execution of step S14, and when the spindle motor requires a time T2 until the spindle motor rotates steadily, the predetermined time Ta is represented by Ta = T1 + T2.
[0019]
In step S16, it is determined whether or not a seek command has been received from the personal computer 40. If a seek command has been received, the process proceeds to step S18 to determine a predetermined time Tb. Here, when the movement (step) of the head is started after a time T1 from the execution of the step S16 and the number of moving tracks is N, the step rate is Tsr, and the settling time is Tst, the predetermined time Tb is represented by Tb = T1 + N × Tsr + Tst. You.
[0020]
Next, in step S20, the current consumption monitor signal is set to a low level for a predetermined time Tb and output, and the process proceeds to step S12. On the other hand, if the seek command has not been received in step S12, the process directly proceeds to step S12.
[0021]
Accordingly, when the flexible disk device 53 receives the spindle motor start command, the flexible disk device 53 switches the motor-on signal shown in FIG. 3B to a low level and starts the rotation of the spindle motor by a time T1 before the time shown in FIG. As shown in A), a low-level current consumption monitor signal is output for a predetermined time Ta. Therefore, as shown in the current consumption waveform in FIG. 3C, during the current consumption increase period due to the activation of the spindle motor, the current consumption monitor signal is at a low level, and the writing of the flash card reader / writer 52 is restricted, and Insufficient supply current from the computer 40 can be avoided.
[0022]
Further, when the flexible disk device 53 receives the seek command, as shown in FIG. 4A, a time T1 before the step signal shown in FIG. And outputs a low-level current consumption monitor signal for a predetermined time Tb. Therefore, as shown in the current consumption waveform in FIG. 4C, the current consumption monitor signal is at the low level during the current consumption increase period during the seek, and the writing of the flash card reader / writer 52 is restricted, and the personal computer 40 Shortage of supply current from the power supply can be avoided.
[0023]
【The invention's effect】
As described above, according to the first and fourth aspects of the invention, the current consumption of the remaining external storage devices is limited to be less than the predetermined value based on the current consumption monitor signal supplied from one external storage device. Therefore, it is possible to prevent the current consumption shortage periods of the plurality of external storage devices from being overlapped with each other, resulting in insufficient current.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of a computer system using a multifunction peripheral according to the present invention.
FIG. 2 is a flowchart of a current consumption monitoring process executed by the flexible disk device.
FIG. 3 is a signal waveform diagram when a spindle motor is started.
FIG. 4 is a signal waveform diagram during a seek.
FIG. 5 is a block diagram of an example of a computer system using a conventional external storage device.
[Explanation of symbols]
40 personal computer 41 USB interface 42 USB
50 Multifunction device 51 USB hub controller 52 Flash card reader / writer 53 Flexible disk device

Claims (4)

A multifunction device comprising a hub controller connected to a computer via a serial bus, and a plurality of external storage devices connected to the computer via the hub controller, wherein the current consumed by the plurality of external storage devices is limited. So,
One of the plurality of external storage devices supplies a current consumption monitor signal to the remaining external storage devices,
The multifunction device according to claim 1, wherein the remaining external storage devices limit operations based on the current consumption monitor signal such that current consumption becomes less than a predetermined value when current consumption of the one external storage device increases. The composite device according to claim 1,
The multifunction apparatus according to claim 1, wherein the one external storage device outputs a current consumption monitor signal indicating an increase in current consumption at a predetermined time when a spindle motor for rotating and driving the flexible disk is started and a predetermined time during a seek operation. The external storage device according to claim 1 or 2,
The apparatus according to claim 1, wherein the remaining external storage device is a flash card reader / writer using a flash memory as a storage medium. A multi-function device including a hub controller connected to a computer via a serial bus, and a plurality of external storage devices connected to the computer via the hub controller, and a current for distributing current consumed by the plurality of external storage devices Distribution method,
Supplying a current consumption monitor signal from one of the plurality of external storage devices to the remaining external storage device;
A current distribution method, wherein when the current consumption of the one external storage device increases, the current consumption of the remaining external storage devices is limited to be less than a predetermined value based on the current consumption monitor signal.

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