On-line detection circuit and device for VGA interface transmission

Abstract

The utility model relates to the technical field of computer systems, in particular to an in-situ detection circuit and device for VGA (Video Graphics Array) interface transmission. Comprising a signal amplifier, a VGA (Video Graphics Array) terminal, a plugging detection module and a computer end, the input end of the signal amplifier is connected with a VGA input source, and the output end of the signal amplifier is connected with the first pin of the VGA terminal; the second pin of the VGA terminal is connected with the input end of the plugging detection module, the output end of the plugging detection module is connected with the input end of the signal amplifier, and the plugging detection module is used for adjusting the internal signal flow direction of the plugging detection module according to the level state of the second pin of the VGA terminal so as to adjust the level state of the input end of the signal amplifier; and the input end of the computer end is connected with the joint of the input end of the signal amplifier and the plugging detection module, and is used for controlling the on-off of the VGA signal according to the level state of the input end of the signal amplifier. The VGA interface transmission in-situ detection method and device have the advantage that the VGA interface transmission in-situ detection function under long-distance VGA transmission can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of computer systems, and in particular to a VGA interface transmission presence detection circuit and device. Background Art

[0002] In multimedia classrooms, large conference centers, exhibitions and other occasions, it is necessary to realize the transmission of VGA (Video Graphics Array) high-definition video signals between computers and remote large-screen displays to ensure teaching quality and display effects. Usually, in order to avoid unnecessary power consumption loss, it is necessary to detect whether the VGA interface is in place. The basic principle is: since the VGA drive source is generally current driven, the drive source outputs a detection pulse current, and because the DC load differs by one time when the VGA display is connected and not connected, the voltage generated by the same intensity of the detection pulse current passing through the DC load also differs by one time. The VGA drive source detects this voltage to know whether the display is connected, thereby realizing the VGA interface in place detection function.

[0003] However, in actual use, it may be necessary to extend the transmission distance of the VGA signal based on demand. Usually, a signal amplifier is added to the transmission path. However, due to the characteristics of the signal amplifier, signal isolation will occur, resulting in the above-mentioned VGA interface in-place detection function cannot be realized. When the monitor is connected, the computer cannot know that the monitor is connected, and thus cannot read the resolution information of the monitor, resulting in display resolution errors and affecting the display effect. When the monitor is removed, the computer cannot know that the monitor has been removed, and it is necessary to power the VGA display control circuit, resulting in unnecessary power loss.

[0004] Therefore, how to realize the in-situ detection function of VGA interface transmission under long-distance VGA transmission is a technical problem that needs to be solved urgently. Utility Model Content

[0005] In order to overcome the deficiencies of the prior art, the present application provides a VGA interface transmission presence detection circuit and device to achieve the beneficial effects of the VGA interface transmission presence detection function under long-distance VGA transmission.

[0006] The technical solutions adopted by this application to solve its technical problems include:

[0007] In a first aspect, the present application provides a VGA interface transmission in-place detection circuit, comprising: a signal amplifier, a VGA terminal, a plug-in detection module, and a computer terminal;

[0008] The input end of the signal amplifier is connected to the VGA input source, and the output end of the signal amplifier is connected to the first pin of the VGA terminal;

[0009] The second pin of the VGA terminal is connected to the input end of the plugging and unplugging detection module, and the output end of the plugging and unplugging detection module is connected to the input end of the signal amplifier, which is used to adjust the internal signal flow direction of the plugging and unplugging detection module according to the level state of the second pin of the VGA terminal, so as to adjust the level state of the input end of the signal amplifier;

[0010] The input end of the computer side is connected to the connection between the input end of the signal amplifier and the plugging and unplugging detection module, and is used to control the on-off of the VGA signal according to the level state of the input end of the signal amplifier.

[0011] By adopting the above technical solution, the signal amplifier is used to amplify the input of the VGA signal and output it as an enhanced VGA signal. However, due to the isolation effect of the signal amplifier, an external circuit is added to bypass the signal amplifier for detection in this application, that is, a plugging and unplugging detection module and a computer side are added. Among them, the plugging and unplugging detection module obtains the level state of the second pin according to the characteristic that the second pin of the VGA terminal changes from high to low when a VGA monitor is connected and changes from low to high when the VGA monitor interface is removed, and adjusts the on-off change of the switching tube in the plugging and unplugging detection module according to the level state of the second pin, so as to change the level state of the input end of the signal amplifier. The computer side determines the plugging and unplugging state of the current VGA monitor by sampling the level state of the input end of the signal amplifier, that is, realizes the in-position detection of the VGA signal, and realizes the beneficial effect of the in-position detection function of the VGA interface transmission under long-distance VGA transmission.

[0012] Optionally, the plugging and unplugging detection module includes a first switch unit and a second switch unit;

[0013] One end of the first switch unit is connected to the second pin of the VGA terminal, the other end is connected to one end of the second switch unit, and the other end of the second switch unit is connected to the input end of the signal amplifier.

[0014] Optionally, the first switch unit includes a first switching tube, a first resistor, a second resistor and a third resistor;

[0015] One end of the first resistor is connected to the second pin of the VGA, and the other end is connected to the base of the first switching tube and one end of the second resistor, and the other end of the second resistor is connected to an external first signal source;

[0016] The collector of the first switching tube is connected to one end of the third resistor and one end of the second switch unit, the other end of the third resistor is connected to an external second signal source, and the emitter of the first switching tube is grounded.

[0017] Optionally, the first switch unit further includes a voltage stabilizing diode;

[0018] One end of the voltage stabilizing diode is connected to the connection point of the first resistor and the VGA, and the other end is grounded.

[0019] Optionally, the first switch unit further includes a first capacitor;

[0020] One end of the first capacitor is connected to the connection point of the first resistor and the first switching transistor, and the other end is grounded.

[0021] Optionally, the second switch unit includes a fourth resistor, a fifth resistor, a sixth resistor, a second switching transistor, a third switching transistor, and a fourth switching transistor;

[0022] The drain of the second switching transistor is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the RIN terminal of the signal amplifier, the gate is connected to the collector of the first switching transistor, and the source is grounded;

[0023] The drain of the third switching transistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the GIN terminal of the signal amplifier, the gate is connected to the collector of the first switching transistor, and the source is grounded;

[0024] The drain of the fourth switching transistor is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the BIN terminal of the signal amplifier, the gate is connected to the collector of the first switching transistor, and the source is grounded.

[0025] Optionally, the ROUT of the signal amplifier is connected to pin 1 of the VGA terminal, the GOUT terminal is connected to pin 2 of the VGA terminal, and the BOUT terminal is connected to pin 3 of the VGA terminal.

[0026] Optionally, the input end of the computer is connected to the RIN terminal, the GIN terminal, and / or the BIN terminal.

[0027] Optionally, the model of the signal amplifier is ISL59833.

[0028] In a second aspect, the present application provides an in-position detection device for VGA interface transmission, which is loaded with the in-position detection circuit for VGA interface transmission described above.

[0029] The beneficial effects of the present application are as follows: The signal amplifier is used to amplify the input of the VGA signal and output it as an enhanced VGA signal. Due to the isolation function of the signal amplifier, the present application adds a peripheral circuit to bypass the signal amplifier for detection, that is, adding a plug-and-play detection module and a computer terminal. Among them, the plug-and-play detection module obtains the level state of the second pin according to the characteristic that the second pin of the VGA terminal changes from high to low when a VGA monitor is connected and changes from low to high when the VGA monitor interface is removed, and adjusts the on-off change of the switching transistor in the plug-and-play detection module according to the level state of the second pin, thereby changing the level state of the input end of the signal amplifier. The computer terminal determines the plug-and-play state of the current VGA monitor by sampling the level state of the input end of the signal amplifier, that is, realizes the in-position detection of the VGA signal, and realizes the beneficial effect of the in-position detection function for the VGA interface transmission under long-distance VGA transmission. Description of the Drawings

[0030] Figure 1 is a schematic diagram of the modules of the in-position detection circuit for VGA interface transmission provided by an embodiment of the present application;

[0031] Figure 2 is a schematic overview diagram of the principle of the in-position detection circuit for VGA interface transmission provided by an embodiment of the present application;

[0032] Figure 3 is the circuit schematic diagram of the in-position detection circuit for VGA interface transmission provided by an embodiment of the present application. Detailed Embodiment

[0033] The present application will be further described below in conjunction with the drawings and embodiments.

[0034] The concept, specific structure and technical effects generated by the present application will be clearly and completely described below in conjunction with the embodiments and the drawings to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present application. In addition, all the connection / connection relationships involved in the patent do not refer to the direct connection of components alone, but refer to the more optimal connection structure that can be formed by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the present invention can be combined with each other without conflicting with each other.

[0035] Refer to Figure 1 , Figure 1 which is a schematic diagram of the modules of the in-position detection circuit for VGA interface transmission provided by an embodiment of the present application, including: a signal amplifier, a DB15, a plug-and-play detection module and a computer terminal;

[0036] The input end of the signal amplifier is connected to the VGA input source, and the output end of the signal amplifier is connected to the first pin of the DB15;

[0037] The second pin of the DB15 is connected to the input end of the plugging and unplugging detection module, and the output end of the plugging and unplugging detection module is connected to the input end of the signal amplifier, which is used to adjust the internal signal flow direction of the plugging and unplugging detection module according to the level state of the second pin of the DB15, so as to adjust the level state of the input end of the signal amplifier;

[0038] The input end of the computer is connected to the connection point between the input end of the signal amplifier and the plugging and unplugging detection module, and is used to control the on / off of the VGA signal according to the level state of the input end of the signal amplifier.

[0039] Specifically, referring to Figure 2 , Figure 2 FIG. is a schematic diagram of the principle of the in-position detection circuit for VGA interface transmission provided by the embodiment of the present application. The signal amplifier (i.e., the BUFFER in the figure, which means buffer and is used for signal isolation and impedance matching) is used to amplify the input of the VGA signal and output it as an enhanced VGA signal. However, due to the isolation effect of the signal amplifier, an external circuit is added to bypass the signal amplifier for detection in the present application, that is, a plugging and unplugging detection module and a computer are added. Among them, the plugging and unplugging detection module obtains the level state of the second pin according to the characteristic that the second pin of the DB15 (i.e., DB9) changes from high to low when a VGA monitor is connected and changes from low to high when the VGA monitor interface is removed, and adjusts the on / off change of the switching tube in the plugging and unplugging detection module according to the level state of the second pin, so as to change the level state of the input end of the signal amplifier. The computer determines the plugging and unplugging state of the current VGA monitor by sampling the level state of the input end of the signal amplifier, that is, realizes the in-position detection of the VGA signal, and realizes the beneficial effect of the in-position detection function for VGA interface transmission under long-distance VGA transmission.

[0040] More specifically, the plugging and unplugging detection module includes a first switch unit and a second switch unit;

[0041] One end of the first switch unit is connected to the second pin of the DB15, the other end is connected to one end of the second switch unit, and the other end of the second switch unit is connected to the input end of the signal amplifier.

[0042] Specifically, one end of the first switch unit samples the level state of the second pin of DB15. There is a switching transistor inside it. The switching transistor adjusts its on / off state according to the level state of the second pin and changes the level state of the sampling point of the second switch unit on the first switch unit. There is a switching transistor inside the second switch unit. It adjusts the on / off state of the switching transistor inside it according to the level state of the sampling point of the first switch unit, thereby adjusting the level state of the signal amplifier. Specifically, by turning the switching transistor inside the second switch unit on and off, the grounding state of the input end of the signal amplifier is adjusted, thereby controlling its level state.

[0043] Refer to Figure 3 , Figure 3 FIG. is the circuit schematic diagram of the in-position detection circuit for VGA interface transmission provided by the embodiment of the present application, which includes a first switch unit and a second switch unit. The first switch unit includes a first switching transistor Q1, a first resistor, a second resistor, and a third resistor;

[0044] One end of the first resistor is connected to the second pin of the VGA, and the other end is connected to the base of the first switching transistor Q1 and one end of the second resistor. The other end of the second resistor is connected to the external first signal source P5V;

[0045] The collector of the first switching transistor Q1 is connected to one end of the third resistor and one end of the second switch unit. The other end of the third resistor is connected to the external second signal source P5V, and the emitter of the first switching transistor Q1 is grounded.

[0046] Specifically, based on the characteristic that the level of the second pin of the VGA is pulled low when a VGA monitor is connected, the base potential of the triode is pulled low and turned off, so that the potential of the collector of the triode (i.e., the first switching transistor Q1 of the present application) is pulled high (since the triode is turned off, its collector is no longer grounded); the second switch unit samples the potential of the collector, thereby adjusting the conduction of the switching transistor inside the second switch unit. Similarly, based on the fact that the level of the second pin of the VGA is pulled high when the VGA monitor interface is removed, a high level pulls up the base of the triode, and the triode is turned on so that its collector is grounded through the emitter. The second switch unit samples the level state of the collector as a low level, thereby correspondingly controlling the switching transistor inside the second switch unit to turn off.

[0047] Among them, the first switch unit further includes a voltage regulator diode EDS1 and a first capacitor;

[0048] One end of the voltage regulator diode EDS1 is connected to the connection point of the first resistor and the VGA, and the other end is grounded.

[0049] Specifically, since the insertion and removal state change of the VGA monitor will cause a drastic change in the level of the second pin of DB15, in order to avoid device damage caused by excessive instantaneous potential difference that may exist, a voltage stabilizing diode EDS1 is set to protect the devices in the circuit.

[0050] One end of the first capacitor is connected to the connection point of the first resistor and the first switching transistor Q1, and the other end is grounded.

[0051] Specifically, the first capacitor is added and grounded to achieve the function of ripple filtering, avoid mis-turn-on and off of the subsequent switching transistor caused by interference signals, and further avoid mis-start of the computer terminal that controls signal turn-on and off based on the collected signal, thereby ensuring the reliability of the circuit and improving the user experience.

[0052] Further, the second switching unit includes a fourth resistor, a fifth resistor, a sixth resistor, a second switching transistor Q2, a third switching transistor Q3, and a fourth switching transistor Q4;

[0053] The drain of the second switching transistor Q2 is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the RIN terminal of the signal amplifier, the gate is connected to the collector of the first switching transistor Q1, and the source is grounded;

[0054] The drain of the third switching transistor Q3 is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the GIN terminal of the signal amplifier, the gate is connected to the collector of the first switching transistor Q1, and the source is grounded;

[0055] The drain of the fourth switching transistor Q4 is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to the BIN terminal of the signal amplifier, the gate is connected to the collector of the first switching transistor Q1, and the source is grounded.

[0056] Specifically, the second switching unit includes three groups of parallel switching transistors, which are NMOS transistors in the embodiment of the present application. When the base of the triode is at a high level, the second switching transistor Q2, the third switching transistor Q3, and the fourth switching transistor Q4 are all turned on, and the RIN terminal, GIN terminal, and BIN terminal of the signal amplifier are respectively pulled down to ground through the fourth resistor, the fifth resistor, and the sixth resistor, thereby simulating the situation where the VGA signal voltage is pulled down when the monitor is inserted. The computer terminal can know that the monitor has been connected by detecting the potential at this point. Further, information about the monitor resolution can be obtained through other signals, so that a VGA signal matching the monitor is output when the input end of the signal amplifier is at a high level.

[0057] Similarly, when the base of the triode is at a low level, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 are all turned off. The RIN terminal, GIN terminal, and BIN terminal of the signal amplifier lack the pull-down to ground of the fourth resistor, fifth resistor, and sixth resistor, and turn to a high level. The computer-side VGA drive source can detect this level to know that the display has been removed, and control the display part circuit to power off and go to sleep, thereby reducing power consumption.

[0058] More specifically, the ROUT of the signal amplifier is connected to pin 1 of the DB15, the GOUT terminal is connected to pin 2 of the DB15, the BOUT terminal is connected to pin 3 of the DB15, and the input terminal of the computer side is connected to the RIN terminal, the GIN terminal, and / or the BIN terminal. Specifically, reference can be made to Figure 3 the position of point A shown.

[0059] Among them, the model of the signal amplifier provided in the embodiment of the present application is ISL59833.

[0060] Specifically, ISL59833 is mainly used for driving video signals, especially excellent in applications where video signals need to be directly coupled to a 75-ohm differential transmission line.

[0061] The above is a specific description of the preferred embodiment of the present application, but the creation of the present application is not limited to the above embodiment. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the present application. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. An in-position detection circuit for VGA interface transmission, characterized in that, Including: A signal amplifier, a VGA terminal, a plugging detection module, and a computer terminal; The input end of the signal amplifier is connected to a VGA input source, and the output end of the signal amplifier is connected to the first pin of the VGA terminal; The second pin of the VGA terminal is connected to the input end of the plugging detection module, and the output end of the plugging detection module is connected to the input end of the signal amplifier, which is used to adjust the internal signal flow direction of the plugging detection module according to the level state of the second pin of the VGA terminal, so as to adjust the level state of the input end of the signal amplifier; The input end of the computer terminal is connected to the connection point between the input end of the signal amplifier and the plugging detection module, and is used to control the on / off of the VGA signal according to the level state of the input end of the signal amplifier.

2. The on-position detection circuit for VGA interface transmission according to claim 1, wherein The plugging detection module includes a first switch unit and a second switch unit; One end of the first switch unit is connected to the second pin of the VGA terminal, the other end is connected to one end of the second switch unit, and the other end of the second switch unit is connected to the input end of the signal amplifier.

3. The in-position detection circuit for VGA interface transmission according to claim 2, wherein The first switch unit includes a first switch tube, a first resistor, a second resistor, and a third resistor; One end of the first resistor is connected to the second pin of the VGA, and the other end is connected to the base of the first switch tube and one end of the second resistor. The other end of the second resistor is connected to an external first signal source; The collector of the first switch tube is connected to one end of the third resistor and one end of the second switch unit. The other end of the third resistor is connected to an external second signal source, and the emitter of the first switch tube is grounded.

4. The in-position detection circuit for VGA interface transmission according to claim 3, characterized in that The first switch unit further includes a voltage stabilizing tube; One end of the voltage stabilizing tube is connected to the connection point between the first resistor and the VGA, and the other end is grounded.

5. The in-position detection circuit for VGA interface transmission according to claim 3, wherein The first switch unit further includes a first capacitor; One end of the first capacitor is connected to the connection point between the first resistor and the first switch tube, and the other end is grounded.

6. The in-position detection circuit for VGA interface transmission according to claim 3, characterized in that, The second switch unit includes a fourth resistor, a fifth resistor, a sixth resistor, a second switch tube, a third switch tube, and a fourth switch tube; The drain of the second switch tube is connected to one end of the fourth resistor. The other end of the fourth resistor is connected to the RIN terminal of the signal amplifier. The gate is connected to the collector of the first switch tube, and the source is grounded; The drain of the third switch tube is connected to one end of the fifth resistor. The other end of the fifth resistor is connected to the GIN terminal of the signal amplifier. The gate is connected to the collector of the first switch tube, and the source is grounded; The drain of the fourth switch tube is connected to one end of the sixth resistor. The other end of the sixth resistor is connected to the BIN terminal of the signal amplifier. The gate is connected to the collector of the first switch tube, and the source is grounded.

7. The in-position detection circuit for VGA interface transmission according to claim 6, characterized in that, The ROUT of the signal amplifier is connected to pin 1 of the VGA terminal, the GOUT terminal is connected to pin 2 of the VGA terminal, and the BOUT terminal is connected to pin 3 of the VGA terminal.

8. The in-position detection circuit for VGA interface transmission according to claim 6, characterized in that, The input end of the computer terminal is connected to the RIN terminal, the GIN terminal, and / or the BIN terminal.

9. The in-position detection circuit for VGA interface transmission according to claim 1, wherein The model of the signal amplifier is ISL59833.

10. An in-position detection device for VGA interface transmission, characterized in that, It is loaded with an in-position detection circuit for VGA interface transmission as described in any one of claims 1-9.

Images