TWI502352B - Kvm extender system and signal extending method - Google Patents

Description

Keyboard-image-mouse extension system and signal extension method

The invention relates to a keyboard-Video-Mouse extender system, in particular to a keyboard-image-mouse extension system and a signal capable of supporting multiple USB Bulk Transfer devices. Extension method.

Referring to Figure 1, a keyboard-image-mouse extension system of the prior art is shown. The proximal console 10 can control the near-end computer 14 via the near-end signal extension unit 12. On the other hand, the remote console 16 can control the near-end computer 14 via the remote signal extension unit 18, the fifth type of network cable (CAT-5) 20, and the near-end signal extension unit 12. The function of the near-end signal extension unit 12 and the remote signal extension unit 18 is to extend the transmission of the signal so that the near-end console 10 and the remote console 16 can manipulate the near-end computer 14 at a greater distance.

However, in the keyboard-image-sliding extension system of the prior art, the remote signal extension unit 18 supports only a single USB device. In other words, when the near-end computer 14 is connected to the first USB port 22 of the near-end signal extension unit 12, the far-end signal extension unit 18 has only a single second USB port 24, that is, only one USB device 26 can be connected at a time. . In some cases, the user wants to connect a plurality of USB devices 26 to the remote signal extension unit 18, for example, a USB flash drive, a USB printer, a USB optical disk drive, but only a single second USB port. 24, which limits the convenience of management and causes inefficiency.

In addition, in the keyboard-image-mouse extension system of the prior art, in order to simulate the USB device 26 to the near-end computer 14, the number of USB host controllers in the remote signal extension unit 18 is generally the same as the near-end signal extension unit 12. The number of USB device controllers (one-to-one relationship) is equal. Therefore, if you want to add a USB device The number of 26, must also increase the number of USB host controllers, the cost of its increase is considerable.

Therefore, it is necessary to propose a solution to the above problems.

An object of the present invention is to provide a keyboard-image-mouse extension system capable of supporting access of a plurality of USB Bulk Transfer devices, which increases the convenience in use and management.

According to the keyboard-image-mouse extension system of the first embodiment of the present invention, the computer host can be coupled to a set of screens, keyboards and/or mice. The extension system includes at least a first module and a second module. The first module is connected to a computer host, and further includes at least a first image conversion unit and M first USB controllers. The first image conversion unit is configured to convert the single-ended image signal output by the host computer into a differential image signal. M first USB controllers are used to simulate at least one USB device to the host computer, so although the USB device is not physically connected to the computer host, the computer host can still detect the USB device(s). This (these) USB devices can be observed by functions such as the device administrator or the Explorer provided by the operating system of the host computer (for example, Windows). The second module is connected to the screen, the keyboard and/or the mouse, and further comprises at least a second image conversion unit, a control interface, a USB hub and a second USB controller. The second image conversion unit is configured to convert the differential image signal into another single-ended image signal or restore the original single-ended image signal to the screen, so that the single-ended image signal output by the host computer can be transmitted through a transmission line. Output to the screen, the length of the transmission line can be greater than the transmission distance allowed by the standard VGA image signal. The control interface is used to connect a keyboard or mouse and output a control signal representing the operation of the keyboard or mouse. The USB hub has an upstream port and N downstream ports, and the N downstream ports can be connected to N A USB device, such as at least a first USB device and a second USB device. The second USB controller is coupled to the upstream port of the USB hub and the control interface, and the second USB controller emulates the host computer. The number (M) of the first USB controller is less than the number (N) of downstream ports of the USB hub. When the number (M) of the first USB controller is 1, the number of downstream ports (N) of the USB hub may be up to 16; when the number (M) of the first USB controller is 2, the number of ports downstream of the USB hub (N) can be up to 32, and the corresponding number of correspondences can be deduced by analogy.

According to the keyboard-image-mouse extension system of the second embodiment of the present invention, the computer host can be coupled to a set of screens, keyboards and/or mice. The extension system includes at least a first module and a second module. The first module is connected to the host computer, and further includes at least a first image conversion unit, a first USB controller, and a signal generator. The first image conversion unit is configured to convert the single-ended image signal output by the host computer into a differential image signal. The first USB controller is configured to simulate at least one USB device to the host computer. The signal generator is coupled to the first image conversion unit for generating at least one test signal. The second module is connected to the screen, the keyboard and/or the mouse, and further comprises at least a second image conversion unit, an image compensation circuit, a control interface, a USB hub and a second USB controller. The second image conversion unit is configured to convert the differential image signal into another single-ended image signal or restore the original single-ended image signal to the screen.

The image compensation circuit compensates another single-ended video signal according to the attenuation of the test signal or the length of a single transmission line coupled between the first module and the second module. The control interface is used to connect a keyboard or mouse and output a control signal representing the operation of the keyboard or mouse. The USB hub has an upstream port and at least two downstream ports for connecting the first USB device and the second USB device. The second USB controller is coupled to the upstream port of the USB hub and the control interface, and the second USB controller simulates the host computer to the USB device. its The single transmission line transmits differential video signals, test signals, control signals, and USB related signals.

According to the keyboard-image-mouse extension system of the third embodiment of the present invention, the computer main body can be coupled to a set of screens, keyboards and/or mice. The extension system includes at least a first module and a second module. The first module is connected to the host computer, and further includes at least a first image conversion unit, a first USB controller, and a signal generator. The first image conversion unit is configured to convert the single-ended image signal output by the host computer into a differential image signal. The first USB controller is configured to simulate at least one USB device. The signal generator is coupled to the first image conversion unit for generating at least one test signal. The second module is connected to the screen, the keyboard and/or the mouse, and further comprises at least a second image conversion unit, an image compensation circuit, a control interface, a USB hub and a second USB controller. The second image conversion unit is configured to convert the differential image signal into another single-ended image signal or restore the original single-ended image signal to the screen. The image compensation circuit compensates another single-ended video signal according to the attenuation of the test signal or the length of a single transmission line coupled between the first module and the second module. The control interface is used to connect a keyboard or mouse and output a control signal representing the operation of the keyboard or mouse. The USB hub has an upstream port and N downstream ports, and the N downstream ports are used to connect a plurality of USB devices. The second USB controller is coupled to the upstream port of the USB hub and the control interface, and the second USB controller emulates the host computer. The single transmission line transmits the above differential image signal, test signal, control signal and USB related signal.

The signal extension method according to the present invention is used for a keyboard-image-mouse extension system, the keyboard-image-mouse extension system has a first module, a second module, and a first module and a first module A single transmission line between two modules, the method comprising at least the steps of: causing a screen, a keyboard, and/or a mouse to pass through the second module, The first USB device and the second USB device are coupled to the second module; the first module emulates the first USB device and the second USB device into a single USB a massive transmission device; and the first module parses the logical unit number of the computer host to access the first USB device or the second USB device.

The signal extension method according to the present invention is used for a keyboard-image-mouse extension system, the keyboard-image-mouse extension system has a first module, a second module, and a first module and a second module A single transmission line between the groups, the method comprising at least the steps of: coupling the screen, the keyboard and/or the mouse to the computer host via the second module, the single transmission line, and the first module. The plurality of USB devices are coupled to the second module; the second module detects the number of USB devices; and when the computer host accesses one of the USB devices, the first module parses the logical unit number of the accessed USB device.

The keyboard-image-mouse extension system and the signal extension method of the present invention can access a plurality of remote USB devices through a USB interface of a computer host, thereby greatly improving management efficiency and increasing management convenience.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

The technical contents of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 2, a keyboard-image-mouse extension system according to a first embodiment of the present invention is illustrated. The keyboard-image-mouse extension system can couple a computer host 200 to a screen 202, a keyboard 204, and/or a mouse 206. The extension system includes a first module 208 and a second module 210. The first module 208 is connected to the computer host 200 and includes a first image conversion unit 212 and M first USB controllers 214. The first image conversion unit 212 is configured to output the computer host 200 The single-ended video signal 246 is converted to a differential video signal 248. The first USB controller 214 is a USB device controller for simulating at least one USB device to the host computer 200. The second module 210 is connected to the screen 202, the keyboard 204, and/or the mouse 206. The second module 210 includes a second image conversion unit 216, a control interface 218, a USB hub 220, and a second USB controller 222. The second image converting unit 216 receives the differential image signal 248 from the first image converting unit 212 through a single transmission line 232 (for example, a fifth type of network cable), and converts the differential image signal 248 into another single end. The image signal 250 is restored to the original single-ended video signal 246 and output to the screen 202, so that the single-ended video signal 246 output by the host computer 200 can be output to the screen 202 via the transmission line 232. The control interface 218 is used to connect the keyboard 204 or the mouse 206 and output a control signal 252 representing the operation of the keyboard 204 or the mouse 206. The USB hub 220 has an upstream port 224 and N downstream ports 226. The N downstream ports 226 can be connected to N USB devices, such as a first USB device 228 and a second USB device 230, wherein the first USB device 228 and the second device The USB device 230 can be a Bulk Transfer device, and the first USB device 228 and the second USB device 230 respectively have different Logical Unit Numbers (LUNs). According to USB related specifications, the number of USB devices (N) can be up to 16 (LUN numbers from 0 to 15). The second USB controller 222 is coupled to the upstream port 224 of the USB hub 220 and the control interface 218, and the second USB controller 222 is a USB device host controller (Host Controller) for the first USB device 228 or the second USB device 230. Simulate the computer host 200. The number (M) of the first USB controllers 214 is less than the number (N) of downstream ports 226 of the USB hub 220. The control interface 218 can be a USB interface or other interface than the USB (for example, a PS/2 interface). When the control interface 218 is a PS/2 interface, the first USB controller 214 can be provided by Cypress. Wafers such as CY7C63722, CY7C63723 or CY7C63743 are implemented. The second USB controller 222 can be implemented by a chip such as CY7C67300 or SL8111HST provided by Cypress. Alternatively, when the control interface 218 is a PS/2 interface, the control interface 218 is coupled to the central processing unit 254 instead of the second USB controller 222. The second USB controller 222 has a hub (Root Hub). Therefore, when the control interface 218 is a USB interface, the second USB controller 222 can connect to the keyboard 204, the mouse 206, and the USB hub 220 via its root hub. communication.

The first module 208 further includes a first RS485 transceiver (Transceiver) 242, and the second module 210 further includes a second RS485 transceiver (Transceiver) 244. The first RS485 transceiver 242 and the second RS485 transceiver 244 are in the first A control signal 252, a USB-related signal, and other signals representing the operation of the keyboard 204 or the mouse 206 are transmitted or received between a module 208 and the second module 210.

The second module 210 further includes a central processing unit (CPU) 254 coupled between the second RS485 transceiver 244 and the control interface 218 for intercepting, parsing, receiving, and transmitting the control signal 252 and USB related signal. The central processing unit 254 can parse the control signal 252 representing the operation of the keyboard 204 or the mouse 206, and wrap the control signal 252 into a packet conforming to the RS485 specification for transmission to the first module 208. Since the central processing unit 254 can parse the control signal 252 representing the operation of the keyboard 204 or the mouse 206, when a user inputs a hot key command via the keyboard 204, the central processing unit 254 can correctly recognize and Make this extension system react. For example, the user can initiate an On-Screen Display Menu via a hotkey command. In addition, since the central processing unit 254 can intercept and parse the USB-related signals, when the computer host 200 to which the first module 208 is connected is not compatible with the keyboard 204 to which the second module 210 is connected (for example) For example, if the computer host 200 is a Macintosh system and the keyboard 204 is a general personal computer (PC) system, the connected keyboard 204 can also be simulated as a Macintosh system keyboard, and the Macintosh system keyboard is unique. Some of the function keys can be reached by the keyboard 204 with some corresponding Hot Key commands.

Please refer to FIG. 3 and FIG. 4 simultaneously, which are respectively a flow chart of a keyboard-image-mouse extension system and a signal extension method thereof according to a second embodiment of the present invention. The difference between FIG. 3 and FIG. 2 is that FIG. 3 further includes a signal generator 234 and an image compensation circuit 256. 4 is a carcass-related flowchart based on the hardware structure of FIG. 2 or FIG. 3, and components of the same reference numerals as those of FIG. 2 have similar functions in FIG. 3 and will not be described again.

In step S410, the screen 202, the keyboard 204, and/or the mouse 206 are coupled to the computer host 200 via the second module 210, the single transmission line 232, and the first module 208.

In step S420, the first USB device 228 and the second USB device 230 are coupled to the second module 210.

In step S430, the first USB controller 214 of the first module 208 simulates the first USB device 228 and the second USB device 230 as a single USB mass transfer device.

In step S440, the first module 208 analyzes the logical unit number of the computer host 200 to access the first USB device 228 or the second USB device 230.

In step S450, the first module 208 converts the single-ended video signal 246 outputted by the host computer 200 into a differential video signal 248, and then transmits it to the second module 210 through a single transmission line 232, and the second module 210 transmits the differential image. The signal 248 is converted to another single-ended video signal 250. The image compensation circuit 256 compensates the single-ended video signal 250 according to the attenuation of the test signal of the signal generator 234 or the length of the single transmission line 232, and outputs the signal to the screen 202.

In step S460, the second module 210 outputs a control signal 252 representing the operation of the keyboard 204 or the mouse 206, and transmits the control signal 252 to the first module 208 through a single transmission line 232.

Please refer to FIG. 5 and FIG. 6 simultaneously, which are respectively a flowchart of a keyboard-image-mouse extension system and a signal extension method thereof according to a third embodiment of the present invention. The difference between FIG. 5 and FIG. 2 is that FIG. 5 further includes a signal generator 234 and an image compensation circuit 256, and has three USB devices 236, 238, 240, and only two USBs in FIG. Devices (first USB device 228 and second USB device 230). The difference between Fig. 5 and Fig. 3 is that there are three USB devices 236, 238, 240 in Fig. 5, and only two USB devices (first USB device 228 and second USB device 230) in Fig. 2. Elements in FIG. 5 that are numbered the same as in FIG. 2 have similar functions and will not be described again.

In step S610, the screen 202, the keyboard 204, and/or the mouse 206 are coupled to the computer host 200 via the second module 210, the single transmission line 232, and the first module 208.

In step S620, a plurality of USB devices 236, 238, and 240 are coupled to the second module 210.

In step S630, the second module 210 detects the number of USB devices 236, 238, 240.

In step S640, when the computer host 200 accesses one of the USB devices 236, 238, 240, the first module 208 parses the logical unit number of the accessed USB device 236, 238 or 240.

In step S650, the first module 208 converts the single-ended video signal 246 outputted by the host computer 200 into a differential video signal 248, and then transmits it to the second module 210 through a single transmission line 232, and the second module 210 transmits the differential image. The signal 248 is converted into another single-ended video signal 250, and the image compensation circuit 256 is based on the signal generator. The attenuation of the test signal of 234 or the length of the single transmission line 232 is compensated for another single-ended video signal 250 and output to the screen 202.

In step S660, the second module 210 outputs a control signal 252 representing the operation of the keyboard 204 or the mouse 206, and transmits the control signal 252 to the first module 208 through a single transmission line 232.

In this embodiment, the number (N) of downstream turns is greater than or equal to the number of first USB controllers 214.

The first embodiment, the second embodiment, and the third embodiment will be explained below to determine whether or not a USB device is connected to the downstream port 226 of the USB hub 220. Referring to FIG. 7, a flow chart for detecting a USB device connected to the downstream port 226 of the USB hub 220 is shown. In step S710, the second module 210 transmits a USB specification GetPortStatus command to the downstream port 226. In step S720, it is determined whether the downstream port 226 has a USB device connected thereto. If not, the process returns to step S710; if so, the process proceeds to step S730. In step S730, the USB class of the USB device connected to the downstream port 226 is checked. In step S740, it is checked whether the USB device connected to the downstream port 226 is a huge transmission class. If yes, proceed to step S750 to enter the mass transfer device processing flow; if not, proceed to step S760 to enter another device processing flow.

Through the above process, the second module 210 can determine the number of USB devices connected to the downstream port 226, and transmit the determined number to the first module 208. The first module 208 sends a USB response to the computer host 200. The GetMaxLUN command of the specification returns the number of discriminants. The host computer 200 respectively assigns a respective number to the USB device connected to the downstream port 226, that is, the above-mentioned logical unit number.

When the computer host 200 wants to access the USB device of the downstream port 226, the first module 208 confirms the USB device to be accessed by the computer host 200 by analyzing one of the fields of the USB specification command packet (CBW) sent by the computer host 200. . Please refer to Referring to Figure 8, the instruction package (CBW) of the USB specification is shown. The first module 208 confirms the USB device that the computer host 200 wants to access by parsing the bCBWLUN field.

With the keyboard-image-mouse extension system and the signal extension method of the present invention, the USB interface of a computer host can access a plurality of remote USB devices, thereby greatly improving management efficiency and increasing management convenience.

While the present invention has been described above by way of example, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. Other different embodiments are contemplated, and the scope of the present invention is defined by the scope of the appended claims.

10‧‧‧ Near-end console

12‧‧‧ Near-end signal extension unit

14‧‧‧ Near-end computer

16‧‧‧ Remote console

18‧‧‧ Near-end signal extension unit

20‧‧‧The fifth category is a network cable

22‧‧‧First USB port埠

24‧‧‧Second USB port埠

26‧‧‧USB device

200‧‧‧Computer host

202‧‧‧ screen

204‧‧‧ keyboard

206‧‧‧ Mouse

208‧‧‧ first module

210‧‧‧ second module

212‧‧‧First Image Conversion Unit

214‧‧‧First USB controller

216‧‧‧Second image conversion unit

218‧‧‧Control interface

220‧‧‧USB hub

222‧‧‧Second USB controller

224‧‧‧Upstream

226‧‧‧ downstream

228‧‧‧First USB device

230‧‧‧Second USB device

232‧‧‧Single transmission line

234‧‧‧Signal Generator

236‧‧‧USB device

238‧‧‧USB device

240‧‧‧USB device

242‧‧‧First RS485 transceiver

244‧‧‧Second RS485 transceiver

246‧‧‧ single-ended video signal

248‧‧‧Differential video signal

250‧‧‧Another single-ended video signal

252‧‧‧Control signal

254‧‧‧Central Processing Unit

256‧‧‧Image Compensation Circuit

S410~S460‧‧‧Steps

S610~S660‧‧‧Steps

S710~S760‧‧‧Steps

1 is a keyboard-image-mouse extension system of the prior art; FIG. 2 is a keyboard-image-mouse extension system according to a first embodiment of the present invention; FIG. 3 and FIG. The keyboard-image-mouse extension system according to the second embodiment of the present invention is respectively shown; the fifth and sixth diagrams respectively show the keyboard-image-mouse extension system and the signal thereof according to the third embodiment of the present invention. A flowchart of the extension method; FIG. 7 is a flow chart showing the detection of a USB device connected downstream of the USB hub; and FIG. 8 is a diagram showing a USB specification command packet (CBW).

200‧‧‧Computer host

202‧‧‧ screen

204‧‧‧ keyboard

206‧‧‧ Mouse

208‧‧‧ first module

210‧‧‧ second module

212‧‧‧First Image Conversion Unit

214‧‧‧First USB controller

216‧‧‧Second image conversion unit

218‧‧‧Control interface

220‧‧‧USB hub

222‧‧‧Second USB controller

224‧‧‧Upstream

226‧‧‧ downstream

228‧‧‧First USB device

230‧‧‧Second USB device

232‧‧‧Single transmission line

242‧‧‧First RS485 transceiver

244‧‧‧Second RS485 transceiver

246‧‧‧ single-ended video signal

248‧‧‧Differential video signal

250‧‧‧Another single-ended video signal

252‧‧‧Control signal

254‧‧‧Central Processing Unit

Claims (29)

A keyboard-image-mouse extension system, which can couple a computer host to a screen, a keyboard and/or a mouse. The extension system comprises at least: a first module connected to the computer host, the first The module further comprises: a first image conversion unit for converting a single-ended image signal outputted by the host computer into a differential image signal; and M first USB controllers for simulating at least one USB And a second module connected to the screen, the keyboard and/or the mouse, the second module further comprising: a second image conversion unit for converting the differential image signal to another a single-ended video signal is output to the screen; a control interface is used to connect the keyboard or the mouse, and output a control signal representing the keyboard or the mouse operation; a USB hub having an upstream port and N downstream ports, the N downstream ports can be connected to at least one first USB device and a second USB device; and a second USB controller coupled to the upstream port of the USB hub and the control interface, and the Two USB controllers simulate this The computer host, wherein the number (M) of the first USB controller is less than the number (N) of the downstream ports of the USB hub. The keyboard-image-sliding extension system of claim 1, wherein the first USB device and the second USB device respectively have different logical unit numbers. Keyboard-image-slider extension system as described in claim 1 The system, wherein when the number (M) of the first USB controller is 1, the number (N) of the downstream ports is at most 16. The keyboard-image-mouse extension system of claim 1, wherein the first module further comprises at least a first RS485 transceiver, and the second module further comprises at least a second RS485 transceiver. The first RS485 transceiver and the second RS485 transceiver transmit or receive the control signal between the first module and the second module. The keyboard-image-mouse extension system of claim 1, wherein the first USB controller is a USB device controller. The keyboard-image-mouse extension system of claim 1, wherein the second USB controller is a USB host controller. The keyboard-image-mouse extension system of claim 2, wherein the first module analyzes a logical unit number of the computer host to access the first USB device or the second USB device. A keyboard-image-mouse extension system, which can couple a computer host to a screen, a keyboard and/or a mouse. The extension system comprises at least: a first module connected to the computer host, the first The module further comprises: a first image conversion unit for converting one of the single-ended image signals outputted by the host computer into a differential image signal; and a first USB controller for simulating at least one USB device; And a signal generator connected to the first image conversion unit for generating a test signal; and a second module connected to the screen, the keyboard and/or the mouse, the second module being at least The method includes: a second image conversion unit configured to convert the differential image signal Converting to another single-ended video signal and outputting to the screen; an image compensation circuit, according to the attenuation of the test signal or the length of a single transmission line coupled between the first module and the second module, The other single-ended video signal is compensated; a control interface is used to connect the keyboard or the mouse, and output a control signal representing the keyboard or the mouse operation; a USB hub having an upstream port and at least Two downstream ports, the at least two downstream ports are configured to connect a first USB device and a second USB device; and a second USB controller is coupled to the upstream port of the USB hub and the control interface, and the The second USB controller simulates the computer host, wherein the single transmission line transmits the differential image signal, the test signal, and the control signal. The keyboard-image-mouse extension system of claim 8, wherein the first USB device and the second USB device are modeled as a single USB mass transfer device. The keyboard-image-mouse extension system of claim 8, wherein the first USB controller simulates the first USB device and the second USB device into a single USB mass transfer device. The keyboard-image-sliding extension system of claim 9, wherein the first USB device and the second USB device respectively have different logical unit numbers. The keyboard-image-mouse extension system of claim 8, wherein the first module further comprises at least a first RS485 transceiver, and the second module further comprises at least a second RS485 transceiver. The first RS485 transceiver is And the second RS485 transceiver transmits or receives the control signal between the first module and the second module. The keyboard-image-mouse extension system of claim 8, wherein the first USB controller is a USB device controller. The keyboard-image-mouse extension system of claim 8, wherein the second USB controller is a USB host controller. The keyboard-image-mouse extension system of claim 8, wherein the single transmission line is a fifth type of network cable. The keyboard-image-mouse extension system of claim 11, wherein the first module analyzes a logical unit number of the computer host to access the first USB device or the second USB device. A keyboard-image-mouse extension system, which can couple a computer host to a screen, a keyboard and/or a mouse. The extension system comprises at least: a first module connected to the computer host, the first The module further comprises: a first image conversion unit for converting one of the single-ended image signals outputted by the host computer into a differential image signal; and a first USB controller for simulating at least one USB device; And a signal generator connected to the first image conversion unit for generating a test signal; and a second module connected to the screen, the keyboard and/or the mouse, the second module being at least The second image conversion unit is configured to convert the differential image signal into another single-ended image signal and output the image to the screen; an image compensation circuit is coupled to the first signal according to the attenuation amount of the test signal The length of a single transmission line between the module and the second module Degree, compensating for another single-ended video signal; a control interface for connecting the keyboard or the mouse, and outputting a control signal representing the keyboard or the mouse operation; a USB hub having an upstream And N downstream ports, the N downstream ports are used to connect a plurality of USB devices; and a second USB controller is coupled to the upstream port of the USB hub and the control interface, and the second USB controller simulates The computer host, wherein the single transmission line transmits the differential image signal, the test signal and the control signal. The keyboard-image-mouse extension system of claim 17, wherein the number (N) of the downstream ports is greater than or equal to the number of the first USB controller. The keyboard-image-sliding extension system of claim 17, wherein the USB devices respectively have different logical unit numbers. The keyboard-image-mouse extension system of claim 17, wherein the first module further comprises at least a first RS485 transceiver, and the second module further comprises at least a second RS485 transceiver. The first RS485 transceiver and the second RS485 transceiver transmit or receive the control signal between the first module and the second module. The keyboard-image-mouse extension system of claim 17, wherein the first USB controller is a USB device controller. The keyboard-image-mouse extension system of claim 17, wherein the second USB controller is a USB host controller. The keyboard-image-mouse extension system of claim 17, wherein the single transmission line is a fifth type of network cable. The keyboard-image-mouse extension system of claim 17, wherein the second module detects the number of the USB devices. The keyboard-image-mouse extension system of claim 19, wherein when the computer host accesses one of the USB devices, the first module parses the logical unit number of the accessed USB device . A signal extension method for a keyboard-image-mouse extension system, the keyboard-image-mouse extension system having a first module, a second module, and a first module and the same a single transmission line between the two modules, the first module includes at least a first USB controller, and the second module includes at least a second USB controller. The method includes at least the following steps: causing a screen, a keyboard And the second USB device and the second USB device are coupled to the second module; the first USB device and the second USB device are coupled to the second module; The first USB controller of the first module simulates the first USB device and the second USB device into a single USB mass transfer device, and the second USB controller of the second module simulates the computer And the first module parses the logical unit number of the computer host to access the first USB device or the second USB device. The method for extending the signal according to claim 26, wherein the first module converts a single-ended video signal outputted by the host computer into a differential video signal, and transmits the signal to the first transmission line through the single transmission line. The second module converts the differential video signal into another single-ended video signal, and compensates the single-ended video signal according to the attenuation of the test signal or the length of the single transmission line, and outputs To the screen; and the second module outputs a control signal representing the keyboard or the mouse operation No. is transmitted to the first module through the single transmission line. The signal extension method of claim 26, wherein the first USB device and the second USB device respectively have different logical unit numbers. The signal extension method of claim 26, wherein the single transmission line is a fifth type of network cable.