TWI403920B - Kvm switch and method capable of providing edid of display for computer coupled thereto - Google Patents

Abstract

The invention discloses a KVM switch and a method capable of providing EDID of a display for computers coupled thereto. The invention updates the EDID of the display stored in the KVM switch automatically or manually. The KVM switch includes a processor, at least one memory and at least one switch. When the KVM switch is booted, when the display is replaced, or when the KVM switch receives an external control signal, the processor of the KVM switch compares the EDID of the display with that stored in the at least one memory. If they are different, the processor overwrites the EDID stored in the at least one memory with the EDID of the display. In addition, the processor transmits a hot plug detection signal to the computers to enable the computers to query and obtain the EDID overwritten in the at least one memory.

Description

KVM switch and method for providing extended display identification data of the screen

The invention relates to a KVM (Keyboard-Video-Monse), in particular to a computer switching capable of providing and updating an extended display identification data (EDID) for a computer coupled to the computer. And methods.

When the general computer is replaced with a screen and directly connected to the screen, the extended display identification data is not automatically updated. Instead, the computer must be turned off first, and after the computer is turned back on, the computer can read the extended display identification data of the screen.

For computers that support HPD (Hot Plug Detection), such as Macintosh computers, when the Macintosh computer replaces the screen and is directly connected to the screen, the hot plug detection signal is detected. When the change is made, the extended display identification data will be updated by itself. Therefore, as long as the display card supports hot plug detection and will update the extended display identification data by itself, it is not necessary to turn off the computer when the screen is replaced.

A KVM switch is a device that controls a plurality of computers with a set of peripheral devices such as a keyboard, a screen, and a mouse. The keyboard and mouse are usually connected to the KVM switch, and the KVM switch will display the identification information and upload the display identification information to the screen. The memory of the KVM switch ensures that all connected to the KVM switch can read the correct extended display identification data when it is turned on.

At the time of power-on, the current KVM switch will perform screen expansion to display the identification data, and display the identification data directly to update the extended display identification data in the memory.

If the KVM switch is replaced or plugged in and removed after the computer is turned on, the KVM switch does not automatically update the extended display identification data in the memory, resulting in the expanded display identification data in the memory is different from the extended display identification of the screen. In the case of data, the computer coupled to the KVM switch reads the non-screen real extended display identification data, which causes problems, such as the screen cannot display the screen, the best resolution, and the delay of the drawing.

For computers that support screen hot plug detection, such as Macintosh computers, when the switch is switched, it is equivalent to the action of plugging and unplugging the screen. The Macintosh computer will detect the plugging and unplugging phenomenon, so it will proceed. The re-reading of the display identification data is expanded, and the re-reading operation causes the screen to be delayed by 5 to 8 seconds when the screen is displayed, resulting in a situation in which the picture cannot be quickly drawn. In addition, when all computers connected to the KVM switch are computers that support hot-swap detection, once the screen is replaced or plugged and unplugged, the KVM switch and all computers must be shut down first to allow multiple computers. After the switch is rebooted, the extended display of the screen is displayed, and the extended display identification data in the memory is updated, the computer can read the correct extended display identification data, so that the computer supporting the hot plug detection of the screen is Replacing or plugging and unplugging the screen to the KVM switch is a tricky and complicated program to deal with.

The main purpose of the present invention is to provide a KVM switch. When the KVM switch is turned on, it will display the identification data and the extended display identification data of the memory stored in the KVM switch. When the two are the same, the update operation is not performed. When the two are different, the display data is overwritten by the expanded display of the screen to overwrite the extended display identification data in the memory, and the update operation is completed.

Another object of the present invention is to provide a multi-computer switcher with a screen inserted In the case of pulling or replacing, it is possible to automatically display the identification information of the screen and the extended display identification data of the memory stored in the KVM switch to confirm whether or not the update of the display identification data in the memory is required.

Another object of the present invention is to provide a KVM switch that allows a user to manually overwrite the extended display identification data in the memory by a hot key to complete the manual update operation.

Another object of the present invention is to provide a KVM switch. For a computer that supports hot swap detection, when the KVM switch is switched, a quick drawing can be achieved. In addition, this type of computer can perform hot plug detection control and automatically update and display the identification data.

Another object of the present invention is to provide a method for providing extended display identification data of a screen, which can be coupled to a computer of a KVM switch to obtain a display and identification data that is correctly displayed on the screen.

The KVM switch of the present invention is coupled to at least one computer to a screen, wherein the screen has a first extended display identification data, and the KVM switch includes a processor, at least one memory, and at least one switch. The processor is coupled to the screen and the computer for receiving the first extended display identification data and outputting a hot plug detection signal to the computer. The memory is coupled to the processor for storing a second extended display identification data. The switch selectively couples the computer to one of the screen and the memory to provide the first extended display identification data or the second extended display identification data to the computer.

When the KVM switch is turned on, the screen is inserted or removed, or the external control signal is received, the processor compares whether the first extended display identification data and the second extended display identification data are the same. When the processor compares the first extended display identification data with the second extended display identification data, the control memory is first expanded The display identification data overwrites the second extended display identification data. At the same time, by the control of the hot plug detection signal, the computer reads the correct extended display identification data.

When the KVM switch detects the insertion or removal of the screen or receives an external control signal, and the processor compares the first extended display identification data with the second extended display identification data, the processor is hot-plugged. The control of the detection signal is extracted, so that the computer reads the second extended display identification data of the memory, that is, reads the correct display identification data to the screen.

The invention provides a method for expanding display identification data of a screen, comprising the steps of: inquiring a first extended display identification data of the screen; and displaying the first extended display identification data and the second extended display identification stored in one of the at least one memory The data is compared; and when the comparison result is different, the second extended display identification data is overwritten by the first extended display identification data, and a hot plug detection signal is transmitted to the computer, so that the computer reads the first from the memory. Expand the display identification data. Alternatively, when the comparison result is the same, a hot plug detection signal is transmitted to the computer, so that the computer reads the second extended display identification data from the memory.

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

Please refer to FIG. 1A, which is a block diagram of the application of the KVM switch 10 according to the first embodiment of the present invention. The KVM switch 10 is coupled to the computers 150 and 152 to the screen 160, and the screen 160 has a first extended display identification data. The KVM switch 10 includes a processor 100, two memories 110, 112, two switches 120, 122, a multiplexer 130, and an image signal interface switch 132. The processor 100 is coupled to the screen 160 and the computers 150 and 152 for receiving the first extended display identification data of the screen 160, and outputting a hot plug detection (HPD) 140 to the computer 150. 152. The memory 110 and 112 are coupled to the processor 100 through the multiplexer 130 for storing a second extended display identification data. The memory 110, 112 may be a volatile memory or a non-volatile memory. It should be noted that the memory 110, 112 may also be directly coupled to the processor 100 without passing through the multiplexer 130. The function of the multiplexer 130 is to provide the processor 100 to write the first extended display identification data of the screen 160 into the memory 110, 112 respectively by switching. The switch 120 can selectively couple the computer 150 to one of the screen 160 and the memory 110 for providing the first extended display identification data or the second extended display identification data of the computer 150. The switch 122 can selectively couple the computer 152 to one of the screen 160 and the memory 112 for providing the first extended display identification data or the second extended display identification data of the computer 152. In this embodiment, the KVM switch 10 can be switched to the computer 150, so the computer 150 reads the first or second extended display identification data from the memory 110 or the screen 160, and the computer 152 reads the second extension from the memory 112. Display identification data. The image signal interface switch 132 is used to select one of the computer 150 and the computer 152 to transmit audio and video data to the screen 160, such as a digital video interface (DVI, Digital Video Interface), and a high definition multimedia interface (HDMI, High Definition Multimedia Interface). ), Video Graphics Array Interface (VGA, Video Graphics Array Interface).

When the KVM switch 10 is turned on, the processor 100 automatically compares the first extended display identification data of the screen 160 with the second extended display identification data stored in the memory 110, 112. When the two are the same, the processing is processed. The device 100 does not need to be updated. When the two are different, the processor 100 maintains the hot plug detection The number 140 is transmitted to the computer 150, 152 for a first level, and the first extended display identification data of the screen 160 is overwritten by the multiplexer 130 to overwrite the second extended display identification data in the memory 110, 112, respectively. After the body 110, 112 stores the first extended display identification data of the screen 160, the processor 100 converts the hot plug detection signal 140 from the first level to the second level.

In this embodiment, the first level is lower than the second level. Please also refer to FIG. 1B, which is a waveform diagram of the hot plug detection signal 140 transmitted by the processor 100 to the computers 150 and 152. As can be seen from the figure, the hot plug detection signal 140 is pulled from the low level to the high level. Therefore, when the processor 100 compares the display 160 with the extended display identification data of the memory 110 and the 112, the hot plug detection signal 140 is maintained at a low level, and after the memory 110 and 112 are updated, the The hot plug detection signal 140 is pulled from the low level to the high level. When the KVM switch 10 is switched from the computer 150 to the computer 152, the processor 100 maintains the hot plug detection signal 140 as the second level. In this embodiment, the CPU 100 maintains the high level and maintains the same level. The purpose is to enable the computer to support the screen hot plug detection. When the KVM switch 10 is switched, the computer 150 or 152 is always connected to the screen 160. Otherwise, the computer 150 or 152 will detect the screen when switching. 160 plugging or replacing and re-reading the extended display identification data, causing the drawing time to be delayed by several seconds. It should be particularly noted that the first level can also be higher than the second level, and the processing procedure is similar to the above.

It should be noted that the hot plug detection signal 140 can be pulled down from the high level to the low level. Therefore, when the processor 100 compares the display 160 with the expanded display identification data of the memory 110 and 112, the hot plug detection signal 140 is maintained at a high level, and after the memory 110 and 112 are updated, the processor 100 The hot plug detection signal 140 is pulled from the high level to the low level. When the KVM switch 10 is cut from the computer 150 When switching to the computer 152, the processor 100 maintains the hot plug detection signal 140 at a low level.

Please refer to FIG. 2A, which is a block diagram of the application of the KVM switch 20 in accordance with the second embodiment of the present invention. The KVM switch 20 is coupled to the computers 250 and 252 to the screen 260. The screen 260 has a first extended display identification data. The KVM switch 20 includes a processor 200, two memories 210, 212, two switches 220, 222, a multiplexer 230, and an image signal interface switch 232. The processor 200 is coupled to the screen 260 and the computers 250 and 252 for receiving the first extended display identification data of the screen 260 and outputting a hot plug detection signal 240 to the computers 250 and 252. The memory 210 and 212 are coupled to the processor 200 through the multiplexer 230 for storing the second extended display identification data. The memory 210, 212 may be a volatile memory or a non-volatile memory. It should be noted that the memory 210, 212 may also be directly coupled to the processor 200 without passing through the multiplexer 230. The function of the multiplexer 230 is to provide the processor 200 to write the first extended display identification data of the screen 260 into the memory 210, 212 respectively by switching. The switch 220 can selectively couple the computer 250 to one of the screen 260 and the memory 210 for providing the first extended display identification data or the second extended display identification data of the computer 250. The switch 222 can selectively couple the computer 252 to one of the screen 260 and the memory 212 for providing the first expanded display identification data or the second extended display identification data of the computer 252. In this embodiment, the KVM switch 20 can be switched to the computer 250, so the computer 250 reads the first or second extended display identification data from the memory 210 or the screen 260, and the computer 252 reads the second extension from the memory 212. Display identification data. The image signal interface switcher 232 is used to select one of the computer 250 and the computer 252 to transmit audio and video data to the screen 260, such as a digital image interface, a high definition multimedia interface, and a video graphics array. interface.

When the processor 200 detects that the screen 260 is plugged or unplugged or replaced, the processor 200 compares whether the first extended display identification data and the second extended display identification data are the same; when the two are different, the processor 200 maintains hot plug detection. The test signal 240 is transmitted to the computer 250 and 252 for a first level, and the first extended display identification data of the screen 260 is overwritten by the multiplexer 230 to respectively overwrite the second extended display identification data in the memory 210, 212. After the memory 210, 212 stores the first extended identification data of the screen 260, the processor 200 converts the hot plug detection signal 240 from the first level to the second level, and then converts to the first level. The hot swap detection signal 240 of the two-level conversion causes the computer 250 or 252 to detect that the screen 260 is turned off and on, or detects that the screen 260 is plugged or replaced, and the switch 2 is issued to the KVM switch 20 The request for displaying the identification data is expanded, and the first extended display identification data is read from the memory 210, 212, so as to read the correct expanded display identification data.

When the processor 200 compares the first extended display identification data of the screen 260 with the second extended display identification data of the memory 210, 212, the processor 200 converts the hot plug detection signal 240 from the first level to the first level. The second level is converted to the first level. As described above, the hot swap detection signal 240 of the two level conversions causes the computer 250 or 252 to detect that the screen 260 is turned off and then turned on, or is Detected. The screen 260 is inserted or removed, and the KVM switch 20 is requested to expand the display identification data. Since the first extended display identification data of the screen 260 is the same as the second extended display identification data of the memory 210 and 212, The second extended display identification data of the memory 210, 212 is directly read, that is, the purpose of reading the correct expanded display identification data of the screen 260 is achieved.

In this embodiment, the first level is higher than the second level. Please also refer to section 2B The figure is a waveform diagram of the hot plug detection signal 240 transmitted by the processor 200 to the computers 250 and 252. As can be seen from the figure, the hot plug detection signal 240 is pulled from the high level to the low level and then pulled high to the high level. Therefore, when the processor 200 compares the display 260 with the extended display identification data of the memory 210 and 212, the hot plug detection signal 240 is maintained at a high level, and after the memory 210, 212 is updated, the heat is applied. The plug detection signal 240 is pulled down from the high level to the low level, and then pulled up to the high level, as if it were the same negative pulse. When the processor 200 compares the screen 260 with the expanded display identification data of the memory 210 and 212, it is not necessary to update the extended display identification data of the memory (of course, the first extended display identification data may be used to cover the memory. Second, the display identification data is extended, and the hot plug detection signal 240 is maintained at a high level, and then the hot plug detection signal 240 is pulled from the high level to the low level, and then pulled high to the high level. Such as the same negative pulse (pulse). When the KVM switch 20 is switched from the computer 250 to the computer 252, the processor 200 maintains the hot plug detection signal 240 as the first level. In this embodiment, the CPU maintains the high level and maintains the level unchanged. The purpose is to enable the computer 250, 252 to always be coupled to the screen 260 when the KVM switch 20 is switched, otherwise the computer 250 is switched when the KVM switch 20 is switched. 252 will detect the insertion or removal of the screen 260, and re-inquire and read the extended display identification data, causing the drawing time to be delayed by several seconds. It should be particularly noted that the first level can also be lower than the second level, and the processing procedure is similar to the above.

It should be noted that the hot plug detection signal 240 can be pulled from the low level to the high level and then pulled down to the low level. Therefore, when the processor 200 compares the display 260 with the extended display identification data of the memory 210 and 212, the hot plug detection signal 240 is maintained at a low level. After the memory 210 and 212 are updated, The hot plug detection signal 240 is pulled from the low level to the high level, and then pulled down to the low level, just like the same positive pulse. When the processor 200 compares the screen 260 with the expanded display identification data of the memory 210 and 212, it is not necessary to update the extended display identification data of the memory (of course, the first extended display identification data may be used to cover the memory. Secondly, the display identification data is expanded. First, the hot plug detection signal 240 is maintained at a low level, and then the hot plug detection signal 240 is pulled from the low level to the high level, and then pulled down to the low level. Such as the same positive pulse (pulse). When the KVM switch 20 is switched from the computer 250 to the computer 252, the processor 200 maintains the hot plug detection signal 240 at a low level.

Please refer to FIG. 3A, which is a block diagram of the application of the KVM switch 30 in accordance with the third embodiment of the present invention. The KVM switch 30 is coupled to the computers 350 and 352 to the screen 360, and the screen 360 has a first extended display identification data. The keyboard 370 is coupled to the KVM switch 30 for generating an external control signal to the KVM switch 30. The KVM switch 30 includes a processor 300, two memories 310, 312, two switches 320, 322, a multiplexer 330, and an image signal interface switch 332. The processor 300 is coupled to the screen 360 and the computers 350 and 352 respectively for detecting the external control signal transmitted by the keyboard 370, receiving the first extended display identification data of the screen 360, and outputting a hot plug detection signal 340 to Computers 350, 352. The memory 310 and 312 are coupled to the processor 300 through the multiplexer 330 for storing the second extended display identification data. The memory 310, 312 can be a volatile memory or a non-volatile memory. It should be noted that the memory 310, 312 may also be directly coupled to the processor 300 without passing through the multiplexer 330. The function of the multiplexer 330 is to provide the processor 300 to write the first extended display identification data of the screen 360 into the memory 310, 312 by switching. The switch 320 can selectively couple the computer 350 to one of the screen 360 and the memory 310. The computer 350 is used to provide the first extended display identification data or the second extended display identification data. The switch 322 can selectively couple the computer 352 to one of the screen 360 and the memory 312 for providing the first extended display identification data or the second extended display identification data of the computer 352. In this embodiment, the KVM switch 30 can be switched to the computer 350, so the computer 350 reads the first or second extended display identification data from the memory 310 or the screen 360, and the computer 352 reads the second extension from the memory 312. Display identification data. The image signal interface switcher 332 is used to select one of the computer 350 and the computer 352 to transmit video and audio data to the screen 360, such as a digital image interface, a high definition multimedia interface, and a video graphics array interface.

When the processor 300 detects an external control signal from the keyboard 370, the processor 300 compares whether the first extended display identification data and the second extended display identification data are the same; when the two are different, the processor 300 maintains hot swapping. The detection signal 340 is transmitted to the computer 350, 352 for a first level, and the first extended display identification data in the memory 310, 312 is overwritten by the multiplexer 330 with the first extended display identification data of the screen 360. After the memory 310, 312 stores the first extended identification data of the screen 360, the processor 300 converts the hot plug detection signal 340 from the first level to the second level, and then converts to the first level. The hot swap detection signal 340 of the two level conversions causes the computer 350 or 352 to detect that the screen 360 is turned off and on, or detects the screen insertion or replacement, and sends the switch to the KVM switch 30. The request for displaying the identification data is expanded, and the first extended display identification data is read from the memory 310, 312, so as to read the correct extended display identification data.

When the processor 300 compares the first extended display identification data of the screen 360 with the second extended display identification data of the memory 310, 312, the processor 300 converts the hot plug detection signal 340 from the first level to the first level. Second level, then converted to The first level, as described above, the hot swap detection signal 340 of the two level conversions causes the computer 350 or 352 to detect that the screen 360 is turned off and on, or the screen 360 is detected or removed. Replacement, and the request for the extended display identification data is sent to the KVM switch 30. Since the first extended display identification data of the screen 360 is the same as the second extended display identification data of the memory 310, 312, the memory 310 is directly read. The second extension of 312 displays the identification data, that is, the purpose of reading the correct 360 extended display identification data.

In this embodiment, the first level is higher than the second level. Please also refer to FIG. 3B, which is a waveform diagram of the hot plug detection signal 340 transmitted by the processor 300 to the computers 350 and 352. As can be seen from the figure, the hot plug detection signal 340 is pulled from the high level to the low level and then pulled high to the high level. Therefore, when the processor 300 compares the display 360 with the extended display identification data of the memory 310, 312, the hot plug detection signal 340 is maintained at a high level, and after the memory 310, 312 is updated, the heat is applied. The plug detection signal 340 is pulled from the high level to the low level and then pulled high to the high level, as if it were the same negative pulse. When the processor 300 compares the screen 360 with the expanded display identification data of the memory 310 and 312, it is not necessary to update the extended display identification data of the memory (of course, the first extended display identification data may be used to cover the memory. Second, the display identification data is extended, and the hot plug detection signal 340 is maintained at a high level, and then the hot plug detection signal 340 is pulled from the high level to the low level, and then pulled high to the high level. Such as the same negative pulse (pulse). When the KVM switch 30 is switched from the computer 350 to the computer 352, the processor 300 maintains the hot plug detection signal 340 as the first level. In this embodiment, the system maintains the high level and maintains the level unchanged. The purpose is to support the screen hot plug detection computer. When the KVM switch 30 is switched, the computer 350, 352 thinks that it is always coupled with the screen 360. Otherwise, the computer 350, 352 will detect when switching. It is detected that the screen 360 is inserted or removed, and the extended display identification data is re-read, causing the drawing time to be delayed by several seconds. It should be particularly noted that the first level can also be lower than the second level, and the processing procedure is similar to the above. As for the external control signal, in addition to the above-mentioned keyboard 370 can be generated by hot keys, the mouse, the push button switch, the wired/wireless remote controller, and any peripheral device applicable to the computer 350, 352 and the KVM switch 30 Peripherals, etc., can also be used to enable the KVM switch 30 to manually update the display identification data in the memory 310, 312, which can be used as a source of external control signals.

It should be noted that the hot plug detection signal 340 can be pulled from the low level to the high level and then pulled down to the low level. Therefore, when the processor 300 compares the display 360 with the extended display identification data of the memory 310, 312, the hot plug detection signal 340 is maintained at a low level, and after the memory 310, 312 is updated, the heat is applied. The plug detection signal 340 is pulled from the low level to the high level, and then pulled down to the low level, just like the same positive pulse. When the processor 300 compares the screen 360 with the expanded display identification data of the memory 310 and 312, it is not necessary to update the extended display identification data of the memory (of course, the first extended display identification data may be used to cover the memory. Second, the display identification data is extended, and the hot plug detection signal 340 is maintained at a low level, and then the hot plug detection signal 340 is pulled from the low level to the high level, and then pulled down to the low level. Such as the same positive pulse (pnlse). When the KVM switch 30 is switched from the computer 350 to the computer 352, the processor 300 maintains the hot plug detection signal 340 at a low level.

Referring to FIG. 4, a flow chart of a method for displaying display identification information of a screen according to the present invention is provided. The method of the present invention includes the following steps: Step 410, querying the first extended display identification data of the screen; Step 420, storing the first extended display identification data and storing in at least one memory One of the second extended display identification data is compared; in step 420-1, if the comparison result in step 420 is yes (same), the second extended display identification data is not updated, but the hot plug detection signal is transmitted to And the step 420-2, if the result of the comparison in step 420 is no (different), overwriting the second extended display identification data with the first extended display identification data, and transmitting a hot plug detection signal to the computer, so that The computer reads the first extended display identification data from the memory. In addition, when there is a replacement or plug-in screen and a hot key is executed, the processor performs a hot-swap detection signal change regardless of whether the extended display identification data of the KVM switch is updated. Moreover, when there is a replacement or insertion or removal of the screen and the execution of the hot key, the processor may first overwrite the second extended display identification data with the first extended display identification data, regardless of whether the extended display identification data from the screen is changed or not. Hot swap detection signal changes.

The hot plug detection signal is a high level that is pulled down to a low level and then pulled high to a high level signal. Or pull a low level to a high level, and then pull down the signal to a low level. The purpose of the hot plug detection signal is to support the screen hot plug detection computer to detect the insertion or removal of the screen, and automatically read the extended display identification data stored in the memory.

The main advantages of the present invention include: (a) After the KVM switch is turned on, it automatically compares the display and the display data in the memory to display the identification data. At the same time, the display information of the extended display of the screen is overwritten and the extended display identification in the memory is overwritten. Data (in the same time, you can use the extended display of the screen to display the identification data to overwrite the extended display identification data in the memory), so that the computer coupled to the KVM switch can read the correct extended display identification data; (b) When replacing the screen The KVM switch detects that the screen has been replaced, and automatically updates the extended display identification data in the memory; (c) provides the user with the hot key to manually update the extended display identification in the memory. (d) The hot-swap detection signal control method can solve the problem of delay in computer graphics for supporting hot-swap detection.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above is only the preferred embodiment of the present invention, and equivalent modifications or variations made by the present invention in accordance with the spirit of the present invention should be included in the following. Within the scope of the patent application.

10, 20, 30‧ ‧ multi-computer switch

100, 200, 300‧‧ ‧ processors

110, 112, 210, 212, 310, 312‧‧‧ memory

120, 122, 220, 222, 320, 322‧‧‧ switchers

130, 230, 330‧‧‧ multiplexers

132, 232, 332‧‧‧Image Signal Interface Switcher

140, 240, 340‧‧‧ hot plug detection signals

150, 152, 250, 252, 350, 352‧‧‧ computers

160, 260, 360‧‧‧ screen

370‧‧‧ keyboard

1A is a block diagram of a KVM switch application according to a first embodiment of the present invention; FIG. 1B is a waveform diagram of a hot plug detection signal transmitted from a processor to a computer; and FIG. 2A is a second embodiment according to the present invention. Block diagram of the KVM switch application of the example; FIG. 2B is a diagram of the hot plug detection signal waveform transmitted by the processor to the computer; FIG. 3A is a block diagram of the application of the KVM switch according to the third embodiment of the present invention; FIG. 3B is a diagram of a hot plug detection signal waveform transmitted by the processor to the computer; and FIG. 4 is a flow chart of a method for displaying the identification information of the screen according to the present invention.

10‧‧‧Multicomputer switcher

100‧‧‧ processor

110, 112‧‧‧ memory

120, 122‧‧‧Switch

130‧‧‧Multiplexer

132‧‧‧Image Signal Interface Switcher

140‧‧‧hot plug detection signal

150, 152‧‧‧ computer

160‧‧‧ screen

Claims (52)

A KVM switch, coupled to at least one computer to a screen, wherein the screen has a first extended display identification data (EDID), the KVM switch includes: a processor coupled to the screen and the computer Receiving the first extended display identification data and outputting a hot plug detection signal (HPD) to the computer; at least one memory coupled to the processor for storing a second extended display identification data And at least one switch selectively coupling the computer to the screen and one of the memory for providing the first extended display identification data or the second extended display identification data to the computer; After the switch is turned on, the processor is different from the first extended display identification data and the second extended display identification data; when the processor is different from the first extended display identification data and the second extended display identification data The processor maintains the hot plug detection signal as a first level, and the processor controls the memory to overwrite the second extended display identifier with the first extended display identification data. , When the expansion memory storing the first display identification data, the processor converts the hot plug detection signal from the first level to a second level. The KVM switch of claim 1, wherein the memory is a non-volatile memory or a volatile memory. The KVM switch of claim 1, further comprising a multiplexer coupled to the memory to transmit the first extended display identification data to the memory. The KVM switch of claim 1, wherein the first level is lower than the second level. The KVM switch of claim 1, wherein the first level is higher than the second level. In the KVM switch of claim 1, the processor maintains the hot plug detection signal as the second level when switching from one computer to another. The KVM switch of claim 6, wherein the first level is lower than the second level. The KVM switch of claim 6, wherein the first level is higher than the second level. A KVM switch, coupled to at least one computer to a screen, wherein the screen has a first extended display identification data (EDID), the KVM switch includes: a processor coupled to the screen and the computer The processor is configured to detect whether the screen is inserted or removed, and the processor is configured to receive the first extended display identification data and output a hot plug detection signal (HPD) to the computer; at least one memory coupled to the The processor stores a second extended display identification data; and at least one switch selectively couples the computer to the screen and one of the memory for providing the first extended display identification data or the second Expanding the display identification data to the computer; when the processor detects the screen insertion or removal, the processor is the same as the first extended display identification data and the second extended display identification data; Showing the identification data and the second extension than the first extension When the display identification data is different, the processor maintains the hot plug detection signal as a first level, and the processor controls the memory to overwrite the second extended display identification data by using the first extended display identification data. After the memory stores the first extended display identification data, the processor converts the hot plug detection signal from the first level to a second level, and then converts to the first level, so that the computer The first extended display identification data is read from the memory. The KVM switch of claim 9, wherein the memory is a non-volatile memory or a volatile memory. The KVM switch of claim 9, further comprising a multiplexer coupled to the memory to transmit the first extended display identification data to the memory. The KVM switch of claim 9, wherein the first level is lower than the second level. The KVM switch of claim 9, wherein the first level is higher than the second level. In the KVM switch of claim 9, the processor maintains the hot plug detection signal as the first level when switching from one computer to another. The KVM switch of claim 14, wherein the first level is lower than the second level. The KVM switch of claim 14, wherein the first level is higher than the second level. A KVM switch, coupled to at least one computer to a screen, and receiving an external control signal, wherein the screen has a first extended display identification data (EDID), the KVM switch includes: a processor coupled to the screen and the computer for detecting the external control signal, the processor for receiving the first extended display identification data, and outputting a hot plug detection signal (HPD) to the a computer; at least one memory coupled to the processor for storing a second extended display identification data; and at least one switch selectively coupling the computer to the screen and one of the memory for Providing the first extended display identification data or the second extended display identification data to the computer; when the processor detects the external control signal, the processor displays the identification data and the second extension compared to the first extended display Displaying whether the identification data is the same; when the processor is different from the first extended display identification data and the second extended display identification data, the processor maintains the hot plug detection signal as a first level, the process Controlling the memory to overwrite the second extended display identification data with the first extended display identification data, and the processor heats the memory after the memory stores the first extended display identification data overwrite Pulling the detection signal is converted by a first level to a second level, and then converted to the first level, so that the computer reads from the memory the first display identification data expansion. The KVM switch of claim 17, wherein the external control signal is generated by a keyboard coupled to the KVM switch. The KVM switch of claim 17, wherein the external control signal is generated by a mouse coupled to the KVM switch. The KVM switch of claim 17, wherein the external control signal is generated by a button switch provided to one of the KVM switches. The KVM switch of claim 17, wherein the memory is a non-volatile memory or a volatile memory. The KVM switch of claim 17, further comprising a multiplexer coupled to the memory to transmit the first extended display identification data to the memory. The KVM switch of claim 17, wherein the first level is lower than the second level. The KVM switch of claim 17, wherein the first level is higher than the second level. For example, in the KVM switch of claim 17, when the computer is switched to another computer, the processor maintains the hot plug detection signal as the first level. The KVM switch of claim 25, wherein the first level is lower than the second level. The KVM switch of claim 25, wherein the first level is higher than the second level. A method for providing an extended display identification data (EDID) of a screen, coupled to at least one computer of a KVM switch, to obtain a first extended display identification data of a screen, the method comprising the steps of: querying the screen The first extension displays the identification data; the first extended display identification data is compared with the second extended display identification data stored in one of the at least one memory; and when the comparison result is different, the first expansion is performed The display identification data overwrites the second extended display identification data, and transmits a hot plug detection signal (HPD) to the computer, so that the computer reads the first extended display identification data from the memory. The method for expanding the display identification data of the screen as described in claim 28, wherein the hot plug detection signal is lowered to a high level A low level, and then pull up the signal of the high level. The method for extending the display identification data of the screen as described in claim 28, wherein the hot plug detection signal is raised to a high level by a low level, and then pulled down to the low level. Signal. A KVM switch, coupled to at least one computer to a screen, wherein the screen has a first extended display identification data (EDID), the KVM switch includes: a processor coupled to the screen and the computer The processor is configured to detect whether the screen is inserted or removed, and the processor is configured to receive the first extended display identification data and output a hot plug detection signal (HPD) to the computer; at least one memory coupled to the The processor stores a second extended display identification data; and at least one switch selectively couples the computer to the screen and one of the memory for providing the first extended display identification data or the second Expanding the display identification data to the computer; when the processor detects the screen insertion or removal, the processor is the same as the first extended display identification data and the second extended display identification data; When the first extended display identification data is the same as the second extended display identification data, the processor converts the hot plug detection signal from a first level to a second level, and then converts to First level, so that the computer reads from the memory the second identification data further display. The KVM switch of claim 31, wherein the memory is a non-volatile memory or a volatile memory. The KVM switch of claim 31, further comprising a multiplexer coupled to the memory to transmit the first expansion Display the identification data to the memory. The KVM switch of claim 31, wherein the first level is lower than the second level. The KVM switch of claim 31, wherein the first level is higher than the second level. For example, in the KVM switch of claim 31, when the computer is switched to another computer, the processor maintains the hot plug detection signal as the first level. The KVM switch of claim 36, wherein the first level is lower than the second level. The KVM switch of claim 36, wherein the first level is higher than the second level. A KVM switch, coupled with at least one computer to a screen, and receiving an external control signal, wherein the screen has a first extended display identification data (EDID), the KVM switch includes: a processor coupled separately Connecting to the screen and the computer for detecting the external control signal, the processor is configured to receive the first extended display identification data, and output a hot plug detection signal (HPD) to the computer; at least one memory And coupled to the processor for storing a second extended display identification data; and at least one switch selectively coupling the computer to the screen and one of the memory for providing the first extended display Identifying the data or the second extended display identification data to the computer; when the processor detects the external control signal, the processor is the same as the first extended display identification data and the second extended display identification data; When the processor is the same as the first extended display identification data and the second extended display identification data, the processor converts the hot plug detection signal from a first level to a second level, and then the processor converts the hot plug detection signal to a second level. Converting to the first level, the computer reads the second extended display identification data from the memory. The KVM switch of claim 39, wherein the external control signal is generated by a keyboard coupled to the KVM switch. The KVM switch of claim 39, wherein the external control signal is generated by a mouse coupled to the KVM switch. The KVM switch of claim 39, wherein the external control signal is generated by a button switch provided to one of the KVM switches. The KVM switch of claim 39, wherein the memory is a non-volatile memory or a volatile memory. The KVM switch of claim 39, further comprising a multiplexer coupled to the memory to transmit the first extended display identification data to the memory. The KVM switch of claim 39, wherein the first level is lower than the second level. The KVM switch of claim 39, wherein the first level is higher than the second level. For example, in the KVM switch of claim 39, when the computer is switched to another computer, the processor maintains the hot plug detection signal as the first level. The KVM switch of claim 47, wherein the first level is lower than the second level. For example, the KVM switch described in claim 47, wherein The first level is higher than the second level. A method for providing an extended display identification data (EDID) of a screen, coupled to at least one computer of a KVM switch, to obtain a first extended display identification data of a screen, the method comprising the steps of: querying the screen The first extended display identification data; the first extended display identification data is compared with the second extended display identification data stored in one of the at least one memory; and when the comparison result is the same, the hot swap is transmitted A detection signal (HPD) is sent to the computer to cause the computer to read the second extended display identification data from the memory. The method for expanding the display identification data of the screen as described in claim 50, wherein the hot plug detection signal is pulled to a low level by a high level, and then pulled high to the high level. Signal. The method for expanding the display identification data of the screen as described in claim 50, wherein the hot plug detection signal is raised to a high level by a low level, and then pulled down to the low level. Signal.