TWI465915B - Kvm switch system and signal process method thereof - Google Patents

Description

Multi-computer switching system and signal processing method thereof

The invention relates to a multi-computer switching system for a remote management system, in particular to a multi-computer switching system for image signals and a signal processing method thereof.

In the remote control system constructed by the KVM switch, the image of the controlled computer is output to the control device for the user to monitor. However, the existing KVM switch first receives the analog video signal output by the controlled computer, and the analog video signal is directly transmitted to the control device after being arranged through an appropriate path. Alternatively, in a KVM-over-IP system with a network interface, the analog video signal must be transmitted to the KVM switch, and the image processing unit of the KVM switch converts the analog video signal into a digital format. After being converted into digital packet data, it can be transmitted to the control device through the network. However, due to the limited bandwidth of the actual network transmission and the design and cost considerations of such a network interface, the number of expensive image processing units is limited to two or a single digit. Generally, each image processing unit further includes an analog-to-digital converter, an image compression unit, and a video buffer. When more than the aforementioned number of users are connected to the KVM switching system, all users need to share the data traffic that can be processed by the limited image processing unit of the KVM switch, which is limited by the original design. The number of single or single digit video signal transmission channels. For example, a multi-computer switching system with a network interface can control up to 40 controlled computers, but it only has two image processing units. The first and second logged-in users are free to choose the controlled computer they want to control for monitoring. However, when the third user logs in, this third login is limited due to the number of image processing units. Users can only view the first or second login The user is controlled by the same computer screen.

Moreover, remote control of the network can be realized by technologies such as remote desktop sharing, remote desktop or VNC (Virtual Network Computing). However, the foregoing technology is achieved in a software manner, which is limited by the operation of the computer, the operating system of the controlled computer needs to be completed, and the computer operating system can complete the relevant settings of many networks in advance. The aforementioned prior art is also limited to the Windows operating system. When the controlled computer is in the operating system, it cannot be operated in BIOS mode. Moreover, if the operating system of the controlled computer is damaged, the aforementioned software function will also be invalid.

The main object of the present invention is to provide a multi-computer switching system and a signal processing method thereof, which can provide high-quality digital image signals to a control device in a multi-computer switching system, and reduce the load of network transmission.

Another object of the present invention is to provide a multi-computer switching system and a signal processing method thereof. In a multi-computer switching system, an image signal can be provided to the operating device before the operating system of the controlled computer is started.

Another object of the present invention is to provide a multi-computer switching system and a signal processing method thereof. In a multi-computer switching system, a user can implement file sharing between a computer and a controlled computer, or between different controlled computers. Multiple functions such as copying, manipulating screen overlays, partial displays, and virtual desktops.

The multi-computer switching system of the present invention includes a KVM switch, a plurality of signal processing devices, and a driver. The KVM switch has a network interface. The signal processing device is connected to one or more controlled computers, and can receive digital image signals of one or more controlled computers through the first interface and analog image signals of one or more controlled computers through the second interface. The driver is installed on one or more controlled computers to enable one or more controlled computers to output digital video signals. Multi-computer switcher The network interface is coupled to the control computer and outputs one or more digital image signals to the computer. The driver can stop one or more controlled computers to output digital image signals, and the signal processing device switches the output analog image signals to the computer switch. The invention can compress the digital image signal and output it to the KVM switch by using the image signal compression processing unit of the driver or the signal processing device.

The invention discloses a multi-computer switching system, which can control one or more controlled computers for a plurality of control computers. The multi-computer switching system comprises at least: a multi-computer switch with a network interface and M image processing Units; N signal processing devices externally connected to the KVM switch, N signal processing devices connected between the one or more controlled computers and the KVM switch, the signal processing device having a first interface And a second interface, wherein the N signal processing devices can receive one or more digital video signals of the one or more controlled computers through the first interface and receive one of the controlled computers through the second interface or a plurality of analog image signals; and a driver program that can be installed on the one or more controlled computers to enable the one or more controlled computers to output the digital image signals; wherein the KVM switch is through the network The interface is coupled to the control computer, and outputs the one or more digital image signals to the control computer; wherein the plurality of control computers can simultaneously receive independent control from the one or more The maximum number of digital or analog images on a computer is M+N.

The present invention also provides a corresponding signal processing method comprising the steps of: loading a driver into a controlled computer; the driver causes the controlled computer to output a digital image signal; and the signal processing device receives and processes the digital image signal through the first interface; the signal processing The device transmits the processed digital image signal to the KVM switch through the third interface; The processed digital signal is transmitted to the control device by using the KVM switch, and the control signal of the control device is transmitted to the controlled computer through the signal processing device by using the KVM switch. The control signal can be a keyboard signal or a mouse signal, and is transmitted to the controlled computer through the first interface. The first interface can be a USB interface. The second interface can be a VGA interface.

The invention can provide high-quality digital image signals to the control device, and at the same time reduce the load of the network transmission, and also increase the number of transmission channels for processing the image signals by the KVM switch, and improve the performance of the KVM switch. Furthermore, the image signal can still be supplied to the operating device before the controlled computer operating system is started, that is, in the BIOS mode.

Referring to Fig. 1, there is shown a functional block diagram of a first embodiment of the multi-computer switching system of the present invention. The multi-computer switching system of the present embodiment is used in a KVM over IP system with a network interface, including a signal processing device 102, 102-1, a KVM switch 104, and a computer-controlled switch 106, respectively. Drivers 112, 112-1 of 106-1. The KVM switch 104 is connected to the control computers 108 and 108-1 through the network 200 and a network interface 5. The signal processing devices 102 and 102-1 are connected to the control computers 108 and 108-1 through the KVM switch 104. The control signals (keyboard and mouse signals) of the computers 108 and 108-1 can be transmitted to the controlled computers 106 and 106-1 through the network 200, the KVM switch 104, and the signal processing devices 102 and 102-1 to be charged. The computers 106, 106-1 can be controlled by the control computer 108. On the other hand, the signal processing devices 102, 102-1 are connected to the controlled computers 106, 106-1, respectively. Taking the signal processing device 102 as an example, it has a first interface 1 and a second interface 2. The signal processing device 102 receives the digital image signal of the controlled computer 106 through the first interface 1 and receives the received image through the second interface 2 Control computer 106 analog video signal. The controlled computer 106 has an operating system 110, and the driver 112 is installed on the operating system 110 platform of the controlled computer 106 to cause the controlled computer 106 to output digital video signals. In addition to the digital video signal, the first interface 1 can also output the aforementioned control signals (keyboard and mouse signals) to the controlled computers 106, 106-1.

The signal processing devices 102, 102-1 may each have an image signal compression processing unit 114, 114-1. The image signal compression processing unit 114, 114-1 can be used to compress the digital image signals received from the controlled computers 106, 106-1, or receive the analog video signals from the controlled computers 106, 106-1, and then convert the analog video signals. After becoming a digital data, compress it. For example, as shown in the figure, the connection between the signal processing device 102, 102-1 and the KVM switch 104 is transmitted through the third interface 3 of the signal processing device 102, 102-1 and the fourth interface of the KVM switch 104, respectively. The interface 4, wherein the third interface 3 and the fourth interface 4 are connected by an Ethernet cable (CAT5 cable). Therefore, the image signal compression processing unit 114, 114-1 can convert the single-ended signal (RGB plus synchronization signal) received from the controlled computer 106, 106-1 to the analog video signal to be transmitted through the Ethernet cable. After the differential signal format is transmitted to the KVM switch 104 through the third interface 3 and the fourth interface 4. The aforementioned first interface 1 of the signal processing device 102 can be, for example, a USB interface. The second interface 2 can be, for example, a VGA interface (DB-15 connector), and the USB interface transmission line 116 and the VGA interface transmission line 118 are respectively coupled to the controlled computer 106 to respectively receive the digital image signal and the analog video signal of the controlled computer 106. .

The signal processing device 102-1 has the same connection relationship as the signal processing device 102, and details are not described herein.

In the signal processing system of the present invention, the drivers 112, 112-1 can be stored in a computer readable medium (not shown), such as a compact disc or other storage in a CD player. media. Alternatively, the network connected by the controlled computers 106, 106-1 may be downloaded from the server or webpage provided by the manufacturer of the product of the present invention and then installed in the controlled computer 106, 106-1. The present invention is not particularly special. Limited. Moreover, the drivers 112, 112-1 can be set to be activated when the operating system of the controlled computers 106, 106-1 is activated, so that the controlled computers 106, 106-1 can output digital video signals. In the present invention, the digital video signals can be first compressed by the drivers 112 and 112-1, and then output to the signal processing devices 102 and 102-1 for processing. The processing of the digital video signal is a process of converting the digital video signal into digital packet data that can be transmitted through the network. This can be performed by the signal processing device 102, 102-1, and can also be performed by the KVM switch 104. If the image signal from the controlled computers 106, 106-1 is in the digital form, the KVM switch 104 does not need to convert the analog video signal into a digital video signal and compression as in the prior art, then the KVM switch 104 is only responsible for arranging the digital image signal and transmitting it to the selected control computer 108 or 108-1, which can solve the problem of the limited number of image processing units of the prior art, and the data flow is limited by the number of image signal transmission channels. The architecture of the KVM switch 104 can also be greatly simplified. The digital image signal is processed and transmitted to the control computer 108 via the network 200.

When the keyboard signal, the mouse signal and the digital image signal between the controlled computer 106 or 106-1 and the control computer 108 or 108-1 are disabled due to excessive network load or poor communication or any other reason, the driver 112 The 112-1 can automatically detect the occurrence of the transmission disorder, stop the controlled computer 106 or 106-1 from outputting the digital image signal from the first interface 1, and switch the second interface 2 to output the analog video signal. Alternatively, after receiving a command from the KVM switch 104 or the user operating the computer 108, 108-1 to stop outputting the digital image, the controlled computer 106 or 106-1 stops outputting the digital position according to the instruction to stop outputting. Video signal compression processing unit 114 of image signal processing device 102 or 102-1 Or 114-1 will convert the analog video signals received from the controlled computers 106, 106-1 into digital data, and then compress and output the analog video signals after the conversion and compression.

Therefore, since the image signal received by the KVM switch 104 of the present invention is in the digital form, the KVM switch 104 of the present invention does not need to have the image processing unit to perform complex processing and format conversion on the analog video signal as in the prior art. Therefore, the number of image signal transmission channels of the KVM switch 104 can be increased (the number of channels is the number of signal processing devices or the number of controlled computers). The KVM switch 104 of the present invention can only be responsible for the operation of transmitting image signals and keyboard/mouse control signals or a small amount of image processing/compression. And whether the digital video signal output by the controlled computer 106 or 106-1 or the analog video signal after the conversion is compressed by the image signal compression processing unit 114 or 114-1 before transmission, The invention not only can provide high-quality digital image signals, but also can greatly reduce the load of the network 200 transmission, and at the same time increase the number of transmission channels of the image signals and improve the working efficiency of the KVM switch 104.

Furthermore, before the operating systems 110, 110-1 of the controlled computers 106, 106-1 are started, that is, when the controlled computers 106, 106-1 are in the BIOS mode, the signal processing devices 102, 102-1 of the present invention are still Can provide image signals to the computer 108, 108-1. After the operating systems 110, 110-1 are activated, as described above, the signal processing system of the present invention can also use the drivers 112, 112-1 to switch between the output of the digital video signal and the analog video signal.

Moreover, since the present invention can use the drivers 112, 112-1 to directly output digital video signals from the controlled computers 106, 106-1 and then transmit them to the operating computers 108, 108-1 via the network. The present invention can utilize the characteristics of the digital video signal to generate an overlay of the instant picture of the controlled computer 106 or 106-1 and the screen of the operating computer 108, 108-1 on the screen of the computer 108, 108-1. Partition display, Alternatively, a virtual desktop can be generated, and the keyboard or mouse that controls the computer 108 or 108-1 can directly control the controlled computer 106 or 106-1 and operate the computer 108 or 108-1 without switching. It is even possible to display the two screens of the controlled computers 106 and 106-1 on the screen of the control computer 108 or 108-1 at the same time in sections or partitions. Further, various functions such as file sharing, copying, and virtual desktop between the controlled computer 106, 106-1 and the control computer 108 or 108-1 can be realized.

Referring to Figure 2, there is shown a functional block diagram of a second embodiment of the multi-computer switching system of the present invention. The second embodiment is different from the first embodiment in that the control devices 108-2 and 108-3 are a combination of a keyboard, a mouse and a screen, and are physically connected to the KVM switch 104-1 (not through the network connection). ). As described in the first embodiment, after the image signal is decompressed and processed by the KVM switch 104-1, it can be transmitted to the manipulation device 108-2 or 108-3, and then the manipulation device 108-2 or 108- 3 to display. The control signals (keyboard and mouse signals) of the control device 108-2 or 108-3 are also transmitted to the controlled computers 106, 106-1 via the KVM switch 104-1, the signal processing device 102, 102-1.

Similarly, the video signal compression processing unit 114 or 114-1 compresses the digital video signal or the analog video signal before the transmission, and can provide the high quality digital image signal of the control device 108-2 or 108-3. Moreover, the number of transmission channels of the image signal is increased, and the working efficiency of the KVM switch 104 is improved. Moreover, when the controlled computers 106, 106-1 are in the BIOS mode, the image signals can also be provided to the operating device 108-2 or 108-3. After the operating systems 110 and 110-1 of the controlled computers 106 and 106-1 are activated, the drivers 112 and 112-1 can be used to switch between the digital video signals and the output of the analog video signals.

Please refer to FIG. 3 and FIG. 4, which are flowcharts of the signal processing method of the present invention. The detailed steps of the signal processing method of the present invention are described as follows: Step 210, first confirm whether the controlled computer loads the driver, if not, Then, the process proceeds to step 310. If yes, proceed to the next step 220. In step 220, the driver causes the controlled computer to output the digital video signal. In step 230, the digital processing device receives and processes the digital video signal through the first interface. The signal processing device transmits the processed digital image signal to the KVM switch through the third interface; in step 250, the processed digital image signal is transmitted to the operating device or the computer by using the KVM switch; and step 260, using the multi-computer The switch transmits the control signal of the control device to the controlled computer through the signal processing device.

Moreover, in the foregoing step 210, if the controlled computer has not loaded the driver, the following steps are performed, and further, when the transmission obstacle between the controlled computer and the control device occurs or the switch from the KVM switch or the control device is received, the switch is performed. When the command of the analog image signal is output, the following steps may be performed: Step 310, the controlled computer outputs the analog video signal to the signal processing device through the second interface; and in step 320, the signal processing device converts and compresses the analog video signal into a digital position. Data; in step 330, the signal processing device transmits the converted and compressed analog video signal (digital data) to the operating device or the computer through the KVM switch; and in step 340, the decompressing and converting the digital data by using the operating computer becomes Analog video signal.

If it is the second embodiment shown in the second figure, in step 340, the multi-computer switch 104-1 is used for decompression and or digital/analog signal conversion. For example, the manipulation device is a group of a keyboard, a mouse, and a screen in the second embodiment. The steps of the signal processing method of the present invention are different from the foregoing signal processing method corresponding to the first embodiment. If the screen of the control device can only receive the analog video signal, the step 250 can use the KVM switch to send the signal from the signal. The digital image signal of the processing device is converted into an analog image signal, and then transmitted to the control device; in step 330, the signal processing device transmits the converted and compressed analog image signal (digital data) to the computer switcher, and the multi-computer switcher solution The compressed and converted digital data becomes an analog video signal; and in step 340, the KVM switch transmits an analog video signal to the control device.

Referring to FIG. 5A, in more detail, each of the signal processing devices (eg, 102-1) further includes a first selection circuit 11A in addition to the first interface 1, the second interface 2, and the third interface 3. A second selection circuit 11B, a signal generator 13, a single-ended differential converter 14, a processor 15, and an RS485 transceiver 17. As described above, the controlled computer 106-1 can output an analog image 150 or a digital image signal DV. The synchronization signal in the image ratio 150 includes a horizontal synchronization signal H and a vertical synchronization signal V, and the horizontal synchronization signal H and the vertical synchronization signal V may be in a composite form or a non-composite form.

When the controlled computer 106-1 inputs the analog video signal 150 to the signal processing device 102-1 via the second interface 2, the signal generator 13 can selectively generate a test signal T (for example, a pulse of 2 M Hz). ), the use of this test signal T will be explained later. After the test signal T and the component R (or G or B) of the analog video signal 150 outputted by the controlled computer are input to the first selection circuit 11A, the first selection circuit 11A performs selective output under the control of the processor 15. The output signal 160 of the first selection circuit 11A has three sets of signals, including R/T, G/T and B/T, wherein the waveform of R/T is as shown in FIG. 6A. In this embodiment of the invention, the first selection circuit 11A can be three sets of two multiplexers. Composition.

Still referring to FIG. 5A, the output 160 (R/T, G/T, B/T) of the first selection circuit 11A and the horizontal synchronization signal H and the vertical synchronization signal V output by the controlled computer 106-1 are five groups. The signals are input to the single-ended to differential converter 14, and are mixed and converted by the converter 14 and output to the second selection circuit 11B. The output signal 170 of the converter 14 has three groups, respectively labeled as R/T. +V, G/T+H and B/T. The waveform of R/T+V is a signal of a differential form (the signals of the positive polarity end and the negative polarity end are symmetric with each other) as shown in FIG. 6B, which is an exemplary description, and thus the technical field has The person of ordinary knowledge can also understand the waveforms of the output G/T+H and B/T of the converter 14, and therefore will not be described again. This converter 14 can be implemented by an operational amplifier. In addition, the horizontal synchronizing signal H and the vertical synchronizing signal V output by the controlled computer 106-1 may be processed by a synchronous signal encoding circuit (not shown) before being input, and the synchronous signal encoding circuit can convert the polarity of the synchronous signal. Converting the composite sync signal into a non-composite sync signal or converting the non-composite sync signal into a composite sync signal.

The second selection circuit 11B is connected to a third interface 3 (e.g., an RJ45 connector), and the third interface 3 is connected to a CAT5 cable 570 having four pairs of twisted pairs. In this embodiment, the second selection circuit 11B can be implemented by a multiplexer. When the controlled computer 106-1 outputs the analog video signal 150, the three sets of signals R/T+V, G/T+H and B/T output by the second selection circuit 11B are carried in the CAT5 cable 570. The three pairs of twisted pairs are then received via the fourth interface 4 by a KVM switch 104 connected at the other end as shown in FIG.

Still referring to FIG. 5A, in this embodiment, when the controlled computer 106-1 outputs a digital image via a USB port, the digital video signal DV representing the digital image can be transmitted through the first interface 1 (for example, a USB device). Connector) input to the signal The processor 15 of the device 102-1. In an embodiment, the processor 15 can have a USB device controller 15A and an image signal compression processing unit 114-1. The USB device controller 15A can simulate a USB keyboard, mouse or other type of USB peripheral device to the controlled computer 106-1. The image signal compression processing unit 114-1 can compress the digital image signal DV. Moreover, the controlled computer 106-1 can also directly output a compressed digital image signal. When the controlled computer 106-1 outputs the digital video signal DV, under the control of the processor 15, the second selection circuit 11B can output the DV to one of the CAT5 cables 570, and then as shown in FIG. The KVM switch 104 connected to the other end shown in the figure is received via the fourth interface 4. In other words, the second selection circuit 11B can control the output of the analog video signal or the digital video signal to the KVM switch 104.

On the other hand, the processor 15 also receives and processes signals from the RS485 transceiver by one of the CAT5 cables 570, for example (including but not limited to) being transmitted by the KVM switch 104 to represent the user. The signal K/M for keyboard/mouse operation performed by the computer 108 or 108-1 is controlled. The processor 15 then parses and processes the signal K/M representing the keyboard/mouse operation, and then transmits it to the controlled computer 106-1 via the first interface 1. Thus, the computer 108 or 108-1 can be controlled and managed to control and manage the computer 106-1. This RS485 transceiver can also be replaced by other types of transceivers, such as Ethernet transceivers. The processor 15 also controls the aforementioned signal generator 13 and the single-ended to differential converter 14.

Since the analog video signals R, G, and B are transmitted to the KVM switch 104 via the signal processing device 102-1 and the CAT5 cable, a phase difference may occur between the two, so that the screen of the 108-1 cannot be The image is correctly displayed, so the KVM switch 104 must detect the phase difference according to the test signal T entrained by the R, G, and B signals and adjust the phase difference of the R, G, and B signals to zero or close. zero.

In another embodiment of the present invention, as shown in FIG. 5B, the signal generator 13 and the first selection circuit 11A may be omitted, so that the analog video signals R, G, and B output by the controlled computer 106-1 are directly Input to the single-ended to differential converter 14. The five groups of signals, such as R, G, B, horizontal synchronizing signal H and vertical synchronizing signal V outputted by the controlled computer 106-1, are input to the single-ended to differential converter 14, and the single-ended to differential converter 14 After mixing and converting, the output is output to the second selection circuit 11B. The output signal 170 of the converter 14 has three groups, which are respectively labeled as R+V, G+H and B. The rest of this embodiment is similar to the embodiment of FIG. 5A described above, and thus will not be described herein. It should be noted that since the synchronization signal output by the controlled computer 106-1 has many different types or combinations, the output signal 170 of the single-ended to differential converter 14 is not limited to the above, and may be Other kinds of waveforms or combinations.

While the invention has been described above in terms of preferred embodiments, it is not intended to limit the invention. Various changes and modifications may be made without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

1‧‧‧ first interface

2‧‧‧second interface

3‧‧‧ third interface

4‧‧‧Fourth interface

5‧‧‧Network interface

11A‧‧‧First selection circuit

11B‧‧‧Second selection circuit

13‧‧‧Signal Generator

14‧‧‧ converter

15‧‧‧ processor

15A‧‧‧USB device controller

17‧‧‧RS485 transceiver

102, 102-1‧‧‧ signal processing device

104, 104-1‧‧‧Multicomputer switcher

106, 106-1‧‧‧ controlled computer

108, 108-1‧‧‧Control computer

108-2, 108-3‧‧‧ Control device

110, 110-1‧‧‧ operating system

112, 112-1‧‧‧ drivers

114, 114-1‧‧‧Image signal compression processing unit

116, 116-1‧‧‧USB interface transmission line

118, 118-1‧‧‧ VGA interface transmission line

150‧‧‧ analog image signal

160‧‧‧Output signal of the first selection circuit

170‧‧‧ Converter output signal

200‧‧‧Network

570‧‧‧CAT5 cable

R‧‧‧ analog image signal red component

G‧‧‧ analog image signal green component

B‧‧‧ analog image signal blue component

H‧‧‧ horizontal sync signal

V‧‧‧Vertical sync signal

T‧‧‧ test signal

DV‧‧‧ digital image signal

Fig. 1 is a functional block diagram showing a first embodiment of the multi-computer switching system of the present invention.

Figure 2 is a functional block diagram showing a second embodiment of the multi-computer switching system of the present invention.

3 and 4 are flowcharts of the signal processing method of the present invention.

Figure 5A is a functional block diagram of an embodiment of the signal processing apparatus of the present invention.

Figure 5B is a functional block diagram of another embodiment of the signal processing apparatus of the present invention.

Figure 6A is the output of the first selection circuit 11A in the present invention, combined with analogy A waveform diagram of the R/T signal 160 like the signal R (or G or B) and the test signal T.

6B is a single-ended to differential converter 14 output of the present invention, combined with analog image signal R (or G or B), test signal T and vertical sync signal V differential form signal R / T + V signal 170 Waveform diagram.

1‧‧‧ first interface

2‧‧‧second interface

3‧‧‧ third interface

4‧‧‧Fourth interface

5‧‧‧Network interface

102, 102-1‧‧‧ signal processing device

104‧‧‧Multicomputer Switcher

106, 106-1‧‧‧ controlled computer

108, 108-1‧‧‧Control computer

110, 110-1‧‧‧ operating system

112, 112-1‧‧‧ drivers

114, 114-1‧‧‧Image signal compression processing unit

116, 116-1‧‧‧USB interface transmission line

118, 118-1‧‧‧ VGA interface transmission line

200‧‧‧Network

Claims (35)

A multi-computer switching system, wherein one or more controlled computers are controlled by a control computer, the multi-computer switching system at least comprising: a multi-computer switch having a network interface; a plurality of signal processing devices, external connections The signal processing device has a first interface and a second interface between the one or more controlled computers and the KVM switch; wherein the signal processing device can receive the one or more devices through the first interface One or more digital video signals of the controlled computer and one or more analog video signals of the controlled computer through the second interface; a driver program can be installed on the one or more controlled computers to enable the One or more controlled computers output the digital image signal; and wherein the KVM switch is coupled to the control computer through the network interface, and outputs the one or more digital image signals to the control computer. The multi-computer switching system of claim 1, further comprising a computer readable medium for storing the driver. The multi-computer switching system of claim 1, wherein the operating computer is coupled to the KVM switch via the network interface via a network. The multi-computer switching system of claim 1, wherein the KVM switch is connected to the signal processing device by an Ethernet cable. The multi-computer switching system of claim 1, wherein the driver causes the controlled computer to output the digital image signal after the operating system of the one or more controlled computers is started. The multi-computer switching system of claim 1, wherein a keyboard signal or a mouse signal of the operating computer is transmitted through the first interface To the controlled computer. The multi-computer switching system of claim 6, wherein when the keyboard signal, the mouse signal, and the digital image signal between the one or more controlled computers and the operating computer are inaccessible, The driver can stop the controlled computer to output the digital image signal, and the second interface outputs the analog image signal. The multi-computer switching system of claim 1, wherein the driver can cause the one or more controlled computers to stop outputting the digital image signal according to the KVM switch or one of the operating computers. The signal processing device switches to output the analog video signal. The multi-computer switching system of claim 1, wherein the signal processing device receives and processes the analog video signal of the controlled computer before the operating system of the one or more controlled computers is started. The multi-computer switching system of claim 1, wherein the first interface is a USB interface. The multi-computer switching system of claim 1, wherein the second interface is a VGA interface. The multi-computer switching system of claim 1, wherein the signal processing device further comprises an image signal compression processing unit for compressing the digital image signal and outputting the signal to the KVM switch. The multi-computer switching system of claim 1, wherein the driver further compresses the digital image signal and outputs the digital image signal to the signal processing device. A multi-computer switching system for controlling a controlled computer to be controlled by a control device, the multi-computer switching system comprising at least: a signal processing device externally connected to the controlled computer, capable of transmitting a first The interface receives a digital video signal of the controlled computer and receives an analog video signal of the controlled computer through a second interface; a driver program can be installed on the controlled computer to enable the controlled computer to output the digital image And a multi-computer switch that couples the signal processing device to the control device to output the digital image to the control device. The multi-computer switching system of claim 14, wherein the operating device comprises a control computer coupled to the KVM switch via a network. The multi-computer switching system of claim 14, wherein the operating device comprises a keyboard, a mouse and a screen. The multi-computer switching system of claim 14, wherein the KVM switch is connected to the signal processing device by an Ethernet cable. The multi-computer switching system of claim 14, wherein the KVM switch is operable to process the digital image signal and transmit the digital image signal to the operating device. The multi-computer switching system of claim 14, wherein the driver causes the controlled computer to output the digital image signal after the operating system of the controlled computer is started. The multi-computer switching system of claim 14, wherein a keyboard signal or a mouse signal of the operating device is transmitted to the controlled computer through the first interface. The multi-computer switching system of claim 20, wherein the driver can stop when the keyboard signal, the mouse signal, and the digital image signal between the controlled computer and the operating device are disabled. The controlled computer The digital image signal is output, and the analog image signal is output by the second interface. The multi-computer switching system of claim 14, wherein the driver can cause the controlled computer to stop outputting the digital image signal according to the KVM switch or one of the operating devices, the signal processing device Switch to output the analog image signal. The multi-computer switching system of claim 14, further comprising a computer readable and writable medium for storing the driver. The multi-computer switching system of claim 14, wherein the signal processing device receives and processes the analog video signal of the controlled computer before the operating system of the controlled computer is started. The multi-computer switching system of claim 14, wherein the first interface is a USB interface. The multi-computer switching system of claim 14, wherein the second interface is a VGA interface. The multi-computer switching system of claim 14, wherein the signal processing device further comprises an image signal compression processing unit for compressing the digital image signal and outputting the digital image to the KVM switch. The multi-computer switching system of claim 14, wherein the driver further compresses the digital image signal and outputs the digital image signal to the signal processing device. A signal processing method for enabling a controlled computer to be controlled by a control device through a multi-computer switching system, the method comprising at least the steps of: loading a driver into the controlled computer; the driver causing the controlled computer Outputting a digital image signal; using one of the external connection signal processing devices to receive and process the digital image signal through a first interface; The digital processing device transmits the processed digital image signal to a KVM switch through a third interface; the processed digital video signal is transmitted to the operating device by using the KVM switch; and the multi-computer is utilized The switch transmits the control signal of one of the control devices to the controlled computer through the signal processing device. The method of claim 29, further comprising the step of: if the driver is not loaded, the controlled computer outputs an analog video signal to the signal processing device via a second interface. The method of claim 30, wherein the driver stops the control when the keyboard signal, the mouse signal, and the digital image signal between the controlled computer and the control device are disabled. The computer outputs the digital image signal, and the second interface outputs the analog image signal. The method of claim 29, wherein the driver can cause the controlled computer to stop outputting the digital image signal according to the KVM switch or one of the operating devices, and the signal processing device switches the output. Analog video signal. In the method of transmitting the digital video signal, the control signal of the control device is transmitted to the controlled computer through the first interface. The method of claim 29, further comprising the step of compressing the digital image signal before the step of transmitting the digital image signal. The method of claim 34, after the step of transmitting the digital image signal, further includes the step of decompressing the digital image signal by using the manipulation device.