WO2018008109A1

WO2018008109A1 - Usb device

Info

Publication number: WO2018008109A1
Application number: PCT/JP2016/070017
Authority: WO
Inventors: 竜太郎今井; 晃稲崎; 健勇水株
Original assignee: Eizo株式会社
Priority date: 2016-07-06
Filing date: 2016-07-06
Publication date: 2018-01-11

Abstract

Provided is a USB device capable of changing, through a simple process, a behavior of the USB device according to the type of a USB host. The present invention provides a USB device which can be connected to a USB host and which is provided with a control unit that controls a behavior of the USB device on the basis of a bus reset behavior performed by the USB host.

Description

USB device

The present invention relates to a USB device that can be connected to a USB host.

In recent years, various USB devices are connected to a USB host using USB (Universal Serial Bus). An example of the USB device is a USB connectable keyboard, and an example of the USB host is a PC (personal computer). In this case, various signals (control signals and data signals) can be transmitted from the keyboard to the PC by USB connection to the PC.

By the way, some USB devices can be connected to various types of USB hosts. For example, a PC equipped with a Windows (registered trademark) OS and a PC equipped with a Mac OS (registered trademark). Some of them can be connected. In such a USB device, there are cases where it is desired to change the signal transmitted from the USB device to the USB host in accordance with the type of OS. However, in the USB connection, the OS information of the PC serving as the USB host is not exchanged within the rules of the USB configuration, and the OS of the USB host cannot be confirmed from the USB device side. For this reason, in order to cause the USB device to transmit a signal suitable for each OS, it is necessary to perform a setting operation in advance by the user, but such a setting operation is troublesome. In Patent Document 1, the OS of the USB host is determined by analyzing a message from the USB host, but complicated processing is required for analyzing the message. For this reason, in the prior art, complicated processing is required to change the behavior of the USB device in accordance with the type of the USB host.

U.S. Pat. No. 8,661,164

The present invention has been made in view of such circumstances, and provides a USB device capable of changing the behavior of a USB device in accordance with the type of the USB host with a simple process.

According to the present invention, there is provided a USB device that is connectable to a USB host and includes a control unit that controls the behavior of the USB device based on the behavior of the bus reset by the USB host.

The present inventor analyzed the bus reset behavior of various USB hosts and found that the bus reset behavior may differ depending on the type of USB host. Then, by using the difference in the behavior of the bus reset, it has been found that the behavior of the USB device can be changed according to the type of the USB host with a simple process, and the present invention has been completed. The bus reset behavior includes bus reset pulses such as the number of bus reset pulses, the interval between bus reset pulses, the width of the bus reset pulse, and the time from when Bus_Vcc becomes Hi until the bus reset pulse is output. Any relevant parameters can be mentioned.

Hereinafter, various embodiments of the present invention will be exemplified. The following embodiments can be combined with each other.
Preferably, the behavior control is performed based on whether there are two or more bus reset pulses within a predetermined time.
Preferably, the control unit determines the model of the USB host based on the behavior of the bus reset, and controls the behavior of the USB device based on the determination result.
Preferably, the control unit determines the type of OS of the USB host based on the behavior of the bus reset, and controls the behavior of the USB device based on the determination result.
Preferably, the behavior control includes changing a signal transmitted from the USB device to the USB host.
Preferably, the signal is a control signal for controlling an operation mode of the USB host.
Preferably, the operation mode includes shutdown, sleep, lock and return of the USB host.
Preferably, the USB device is an HID device.
Preferably, the HID device is configured to generate a key code.
Preferably, the HID device is configured to generate pointer information.

It is a block diagram which shows the connection state of the monitor 1 of an example of a USB device, and PC3 of an example of a USB host. It is a block diagram of the part relevant to the USB connection of the monitor 1 and PC3. The behavior of the bus reset when the USB host is a PC with a Windows OS is shown, (a) shows the behavior when the PC is activated, and (b) shows the behavior when the USB device is connected. When the USB host is a Mac OS-equipped PC, the behavior of bus reset is shown, (a) shows the behavior when the PC is started, and (b) shows the behavior when the USB device is connected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Various characteristic items shown in the following embodiments can be combined with each other. In addition, the invention is independently established for each feature.

<Overall configuration>
An embodiment of the present invention will be described with reference to FIG. In this embodiment, the USB device is the monitor 1 and the USB host is the PC 3. As shown in FIG. 1, the monitor 1 and the PC 3 are connected by a video signal cable 5 such as an HDMI cable, and the video signal from the PC 3 is transmitted to the monitor 1 so that the video is displayed on the monitor 1. ing. The monitor 1 and the PC 3 are connected by USB via the USB cable 7, and the display setting of the monitor 1 is changed by a control signal from the PC 3 or the operation mode (shutdown, (Sleep, lock, and return) can be controlled. The descriptor of the monitor 1 describes that it is a composite device of the monitor class and the keyboard class, so that the PC 3 recognizes that the monitor 1 is both the monitor class and the keyboard class. As shown in FIG. 2, the monitor 1 and the PC 3 include

storage units

1a and 3a that store various data and programs, and

control units

1b and 3b that perform various controls according to the programs. Communication by USB connection is performed under the control of the

control units

1b and 3b. The control unit 1b analyzes the behavior of the bus reset by the USB host (PC3), and controls the behavior of the USB device (monitor 1) based on the analysis result.

<Determination of USB host type based on bus reset behavior>
The USB standard stipulates that the USB host resets the bus when the USB host detects the connection of the USB device. The bus reset is performed when the USB host sends a signal for setting both the data lines + D and −D to a low level of 10 mS or more to the USB device. When the present inventor examined the behavior of the bus reset when the USB host is a PC with a Windows OS and a Mac OS, the results shown in FIGS. 3 to 4 were obtained. FIGS. 3 to 4 show Bus_Vcc and + D, −D AND logic outputs when the PC 3 is started up and when the monitor 1 is connected to the PC 3. In FIG. 3 to FIG. 4, the locations where the AND logic outputs of + D and −D are Low are pulses that make both + D and −D low (hereinafter “bus reset pulse”) w1 to w5 and m1. M3 are output from the USB host to the USB device. The lengths of the bus reset pulses w1 to w5 and m1 to m3 were 10 mS or more. The results shown in FIGS. 3 to 4 are obtained by connecting a USB device with a Full-Speed setting.

Here, the case where the USB host is a PC with Windows OS will be described in detail. As shown in FIG. 3A, when the PC 3 is activated while the monitor 1 is connected to the PC 3, the bus reset pulse w1 is activated when the activation program mounted on the ROM of the motherboard such as BIOS or EFI is activated. Is output once, and then the bus reset pulses w2 and w3 are output with a predetermined interval S1 when the Windows OS is started. The interval S1 between the bus reset pulses w2 and w3 was several tens of milliseconds to hundreds of tens of milliseconds, and was 0.5 seconds or less. Note that the bus reset pulse w1 may not be output depending on the OS version and the type of PC. On the other hand, when the USB device (monitor 1) is connected while the OS is activated, bus reset pulses w4 and w5 are output with a predetermined interval S2 as shown in FIG. 3B. The interval S2 is substantially the same as the interval S1, and is several tens of mS to several tens of mS, and is 0.5 seconds or less. In other words, it was confirmed that the bus reset pulse was output twice at intervals of 0.5 seconds or less when the Windows OS-based PC was started up and when the USB device was connected.

Next, the case where the USB host is a Mac OS PC will be described in detail. As shown in FIG. 4A, when the PC 3 is activated while the monitor 1 is connected to the PC 3, the bus reset pulse m1 is set to 1 when the activation program installed in the ROM of the motherboard such as EFI is activated. After that, the bus reset pulse m2 was output once when the Mac OS was started. The interval S3 between the bus reset pulses m1 and m2 was 1 second to several seconds. Depending on the OS version and the type of PC, the bus reset pulse m1 may not be output. On the other hand, when the USB device (monitor 1) is connected while the OS is activated, the bus reset pulse m3 is output once as shown in FIG. 4B. In other words, one or two bus reset pulses are output when a Mac OS-equipped PC is started and a USB device is connected, and if two bus reset pulses are output, the interval must be 1 second or longer. Was confirmed.

As described above, the bus reset behavior differs between the Windows OS-installed PC and the Mac OS-installed PC both when the OS is started and when the device is connected. For this reason, by analyzing the behavior of the bus reset, it is possible to determine whether the USB host is a Windows OS-installed PC or a Mac OS-installed PC. As a determination method, the following method is exemplified.
(1) Judged by the interval of the bus reset pulse when the OS is started. If it is less than a predetermined reference value (for example: 0.5 seconds), it is a Windows OS-based PC.
(2) Determined by the number of bus reset pulses when the device is connected. A Mac OS-equipped PC for one time and a Windows OS-based PC for twice.
(3) Determined by the interval of the bus reset pulse when the device is connected. If it is less than a predetermined reference value (for example: 0.5 seconds), it is a PC with a Windows OS, and if it exceeds a predetermined reference value, it is a Mac OS PC.

As described above, the USB device according to the present embodiment can discriminate between the Windows OS-based PC and the Mac OS-based PC based on the bus reset behavior, and, as will be described later, according to the type of the USB host. The behavior can be changed as appropriate. In the prior art, the OS is determined by analyzing a message from the USB host, but the message analysis requires complicated processing. For this reason, in the prior art, complicated processing is required to change the behavior of the USB device in accordance with the type of the USB host. On the other hand, in this embodiment, the OS is determined based on the behavior of the bus reset, and such determination is easily performed by detecting each output (or AND logic output) of + D and −D. be able to. This output can be detected by a simple voltage detection circuit. The OS can be discriminated by detecting the number and interval of bus reset pulses based on the detected voltage. Since such an OS discrimination method is much simpler than the conventional technique, according to the present embodiment, the behavior of the USB device can be changed according to the type of the USB host with a simple process. In this embodiment, since the bus reset behavior, which is a specification required by the USB standard, is used, it is possible to determine the type of the USB host without installing a special driver or application in the USB host. There is also an advantage.

<Behavior control of USB device according to USB host type>
In this embodiment, the USB device (monitor 1) transmits a control signal for controlling the operation mode (shutdown, sleep, lock, and recovery) of the USB host (PC3) to the USB host, thereby Control the operation mode. Examples of the control signal include shortcut key commands corresponding to the type of USB host. For example, the shortcut key command for setting the PC to the locked state is “Windows logo key + L” in the Windows OS, and “Shift + CTRL + Power” in the Mac OS.

Here, behavior control when the USB device has an OFF function by a human sensor, an OFF function by a primary power switch, and an OFF function by a secondary power switch will be described.

(1) OFF by human sensor
The human sensor OFF function is designed to save energy when the operator leaves the front of the monitor for the purpose of saving energy when the worker is temporarily away from the monitor. This is a function to turn off. In this case, if the PC is put into sleep or shutdown in conjunction with the power off of the monitor, it takes time until the screen returns when the operator returns to the seat. The screen password lock command is suitable. Therefore, when the monitor is turned off due to the detection of the worker leaving by the human sensor, a control signal for locking the PC is transmitted from the monitor to the PC. Since this control signal differs depending on the type of OS, the operation mode of the PC can be shifted to the locked state by transmitting a control signal corresponding to the OS type.

(2) OFF by secondary power switch
The secondary power supply is turned off most when the worker leaves the seat for a relatively long time. In this case, it is desirable in terms of energy saving to transmit a command for setting the sleep mode in which the screen returns relatively quickly when the operator returns while reducing the power consumption of the PC. In the case of the shutdown, it is necessary to save the document being worked on, and if there is an unsaved document, the shutdown is interrupted, which is not preferable in this scene. Therefore, when the monitor is turned off by the secondary power switch, a control signal for setting the PC to the sleep mode is transmitted from the monitor to the PC. Since this control signal differs depending on the type of OS, the operation mode of the PC can be shifted to the sleep state by transmitting a control signal corresponding to the OS type.

(3) OFF by primary power switch
The primary power switch is turned off when the highest level of power saving is required in the office, such as when the worker goes away from home on a trip or on a business trip. , Sends a PC shutdown command. In this scene, it is assumed that the PC is shut down, and documents are stored before the monitor is turned off, so that the shutdown operation is unlikely to occur. Therefore, when the monitor is turned off by the primary power switch, a control signal for shutting down the PC is transmitted from the monitor to the PC. Since this control signal varies depending on the type of OS, the PC can be shut down by transmitting a control signal corresponding to the OS type.

As described above, according to the present embodiment, the type of the USB host is determined based on the behavior of the bus reset by the USB host, and the behavior of the USB device is controlled based on the determination result. The USB device can be appropriately operated according to the type of the USB host with a simple process without setting the type of the host in advance.

The present invention can also be implemented in the following modes.
In the above embodiment, as an example of behavior control of the USB device, control of a signal transmitted from the USB device to the USB host has been described. However, as behavior control of the USB device, control that does not involve transmission of a signal to the USB host. For example, the behavior of the USB device itself may be controlled according to the type of the USB host. Examples of the behavior of the USB device itself include control of a display unit provided in the USB device. Specifically, when the USB host is a Windows OS-installed PC, a mark indicating that is displayed on the USB device, and when the USB host is a Mac OS-installed PC, a mark indicating that is displayed. The control to display is mentioned.

In the above embodiment, the monitor is exemplified as the USB device, but the USB device may be any device capable of behavior control according to the type of the USB host. The USB device may be, for example, any HID device (a monitor, a keyboard, a mouse, a touch pad, a touch panel, etc.). As the HID device, a device that generates a key code or a device that generates pointer information is preferable.

In the above embodiment, the Windows OS PC and the Mac OS PC are listed as the USB host type, but the USB host type may be a manufacturer type or a motherboard type. The behavior of the bus reset of the PC with the Windows OS is as described in the above embodiment, but the time from when the PC is activated until Bus_Vcc becomes Hi until the bus reset pulses w1, w2, and w3 are output. Alternatively, the time from when the USB device is connected and Bus_Vcc becomes Hi until the bus reset pulses w4 and w5 are output may vary depending on the manufacturer type and the motherboard type. Therefore, based on the behavior of the bus reset by using a table showing the correspondence between the manufacturer type and the motherboard type and the time from when Bus_Vcc becomes Hi until the bus reset pulses w1 to w5 are output. Thus, the type of the manufacturer and the type of the motherboard can be determined, and the behavior of the USB device can be controlled based on the determination result.

In the above embodiment, after determining the USB host type (OS type) based on the bus reset behavior, the USB device behavior control is performed based on the determination result. The USB device behavior control may be performed based on the bus reset behavior without performing the determination. For example, in the case of the above embodiment, when the interval between the bus reset pulses is equal to or less than a predetermined reference value (for example: 0.5 seconds), the first shortcut key command is transmitted and exceeds the predetermined reference value. Alternatively, the second shortcut key command may be transmitted. In such behavior control, the USB device does not determine the type of the USB host, performs the first behavior when the bus reset behavior satisfies a predetermined condition, and performs the second behavior when it does not satisfy the predetermined condition. Is supposed to behave. According to such control, it is possible to appropriately control the behavior of the USB device by setting the predetermined condition and the first and second behaviors in advance.

In the above embodiment, a PC is exemplified as a USB host. However, the USB host may be any electronic device other than a PC that can be connected by USB. For example, when the USB host is a device such as a digital camera or a smartphone (mobile terminal), the number and timing of the bus reset can be arbitrarily set. When such a USB host is connected to a monitor that is a USB device, the monitor recognizes that the USB host is a specific model from the detection result of the bus reset output from the USB host, and matches the model. It can be said that the color table is read and displayed.

Claims

A USB device connectable to a USB host,
A USB device comprising a control unit that performs behavior control of the USB device based on a bus reset behavior by the USB host.
The USB device according to claim 1, wherein the behavior control is performed based on whether or not two or more bus reset pulses exist within a predetermined time.
3. The USB according to claim 1, wherein the control unit determines a model of the USB host based on the behavior of the bus reset, and controls the behavior of the USB device based on the determination result. device.
The control unit according to any one of claims 1 to 3, wherein the control unit determines the type of OS of the USB host based on the behavior of the bus reset, and controls the behavior of the USB device based on the determination result. The USB device as described in any one.
5. The USB device according to claim 1, wherein the behavior control includes changing a signal transmitted from the USB device to the USB host.
The USB device according to claim 5, wherein the signal is a control signal for controlling an operation mode of the USB host.
The USB device according to claim 6, wherein the operation mode includes shutdown, sleep, lock, and recovery of the USB host.
The USB device according to any one of claims 1 to 7, wherein the USB device is an HID device.
The USB device according to claim 8, wherein the HID device is configured to generate a key code.
The USB device according to claim 8 or 9, wherein the HID device is configured to generate pointer information.