A control circuit for switching AV line sequences

Abstract

The utility model provides a control circuit for switching AV line sequence, include: audio amplifier circuit is used for single -channel amplification to double -channel audio signal, and exports audio amplifier signal to the first group switch of line sequence selection circuit, signal output circuit's second interface respectively, video output circuit is used for transmitting video signal to the second group switch of line sequence selection circuit, line sequence selection circuit adopts double -pole double -throw switch, and the first group switch and second group switch are connected to signal output circuit's first interface through the first common end of double -pole double -throw switch respectively, are connected to signal output circuit's third interface through the second common end of double -pole double -throw switch, line sequence selection circuit according to AV line sequence input a configuration signal, and configuration signal is used for controlling the conduction path of first group switch, second group switch. The utility model discloses through switching the output interface adaptation different line sequence's AV line of audio signal and video signal, reaches the effect that improves circuit versatility and reduces cost.

Description

Technical Field

[0001] This utility model relates to the field of audio and video signal processing technology, specifically to a control circuit for switching AV line sequences. Background Technology

[0002] A Mini AV cable is a connector used to transmit standard definition analog audio and video signals. The three plugs of a Mini AV cable are typically distinguished by red, white, and yellow, representing the right channel, left channel, and video signal, respectively. Because standardized AV wiring sequences are widely used in China, existing AV circuits are designed according to this unique wiring sequence.

[0003] As the industry develops, domestically produced audio and video products will be sold in other regions of the world. However, due to the existence of multiple wiring schemes and the lack of standardized AV wiring schemes in some sales locations, the AV cables purchased locally may not be compatible with the set-top box hardware itself. This incompatibility between the purchased cables and the terminal hardware interface significantly impacts the user experience. The usual approach to adapting AV cables to different wiring schemes is to design and manufacture custom circuit boards. However, changing the wiring scheme not only delays production delivery but also increases costs in material management, production line switchover, and maintenance of products with different AV wiring schemes, greatly limiting the product's market adaptability and promotion efficiency.

[0004] Based on the above issues, a survey was conducted on mainstream AV cables in the sales regions. (See [reference needed]) Figure 1-2 It was discovered that the commonly used AV cable wiring sequences in this area include 1234 red-white-yellow-ground and 1234 yellow-white-red-ground, with the right channel audio signal and video signal having different wiring sequences. Therefore, there is an urgent need to design a control circuit capable of switching between these two AV wiring sequences to adapt to AV cables with different wiring sequences. Utility Model Content

[0005] This utility model provides a control circuit for switching AV cable sequences, which is mainly used to solve the problems that existing AV circuits cannot adapt to AV cables with different cable sequences, and that customized circuit design has a long cycle and high cost, thereby improving the versatility of the circuit and reducing the production and maintenance costs of products with different AV cable sequences.

[0006] This utility model achieves the above objectives through the following technical solutions: A control circuit for switching AV line sequences includes an audio amplification circuit, a video output circuit, a line sequence selection circuit, and a signal output circuit. The audio amplification circuit receives a dual-channel audio signal, amplifies the dual-channel audio signal in a single path, and outputs an amplified audio signal to a first set of switches in the line sequence selection circuit and a second interface of the signal output circuit. The video output circuit receives a video signal and transmits the video signal to the second set of switches in the line sequence selection circuit. The line sequence selection circuit uses a double-pole double-throw switch (DPTS) composed of the first set of switches and the second set of switches. The first set of switches and the second set of switches are connected to a first interface of the signal output circuit through a first common terminal of the DPTS and to a third interface of the signal output circuit through a second common terminal of the DPTS. The line sequence selection circuit inputs a configuration signal according to the AV line sequence. The configuration signal is used to control the conduction paths of the first set of switches and the second set of switches to switch the output interfaces of the amplified audio signal and the video signal.

[0007] A further embodiment is that the audio amplification circuit includes an input stage circuit, an amplification stage circuit, and an output stage circuit. The input stage circuit is used to receive the dual-channel audio signal and isolate the DC component in the dual-channel audio signal through a first coupling capacitor to output an AC audio signal to the amplification stage circuit. The amplification stage circuit is used to amplify the AC audio signal and output the amplified audio signal through the output stage circuit.

[0008] A further embodiment is that the amplification stage circuit includes a first resistor circuit, a second resistor circuit, a third resistor circuit, and a first transistor. The base of the first transistor is connected to the audio AC signal and to an external power supply through the first resistor circuit. Its drain is connected to the audio power supply through the second resistor circuit, and its source is grounded through the third resistor circuit. The first resistor circuit, the second resistor circuit, and the third resistor circuit are used to set the static operating point of the first transistor so that it operates in the amplification region.

[0009] A further embodiment is that the amplification stage circuit also includes a power supply filter circuit. The power supply filter circuit adopts an RC filter network and includes a first resistor, a first capacitor, and a second capacitor. The first capacitor and the second capacitor are connected in parallel, one end of which is connected to the external power supply through the first resistor, and the other end is grounded.

[0010] The first capacitor is an electrolytic capacitor used to filter out low-frequency ripple; the second capacitor is used to filter out high-frequency noise.

[0011] A further embodiment is that the line sequence selection circuit includes a configuration circuit and a double-pole double-throw switch chip of model SGM7222. The configuration circuit is connected to the configuration signal and is used to output a high level or a low level to the switch control pin of the double-pole double-throw switch chip according to the configuration signal.

[0012] A further embodiment is that the configuration circuit includes a second transistor and a current-limiting resistor. The base of the second transistor is connected to the configuration signal through the current-limiting resistor, and its drain is connected to the chip power supply along with the power input pin of the double-pole double-throw switch chip. Its source is grounded.

[0013] When the AV line sequence is 1, 2, 3, 4, corresponding to the right channel, left channel, video, and ground function interfaces respectively, the configuration signal is set to a high-level signal to turn on the second transistor.

[0014] When the AV line sequence is 1, 2, 3, 4, corresponding to the video, left channel, right channel, and ground function interfaces respectively, the configuration signal is set to a low level signal, causing the second transistor to be cut off.

[0015] A further embodiment is that the double-pole double-throw switch chip integrates the double-pole double-throw switch and is provided with a first knife switch connection contact point and a second knife switch connection contact point of the first group of switches, as well as a third knife switch connection contact point and a fourth knife switch connection contact point of the second group of switches.

[0016] When the second transistor is turned on, the switching control pin of the double-pole double-throw switch chip is at a low level. At this time, the second knife switch contact point is connected to the first common terminal, and the audio amplification signal is output to the first interface. At the same time, the third knife switch contact point is connected to the second common terminal, and the video signal is output to the third interface.

[0017] When the second transistor is cut off, the switching control pin of the double-pole double-throw switch chip is at a high level. At this time, the first knife switch contact point is connected to the second common terminal, and the audio amplification signal is output to the third interface. At the same time, the fourth knife switch contact point is connected to the first common terminal, and the video signal is output to the first interface.

[0018] A further embodiment is that the signal output circuit integrates the right channel, left channel, video, and ground functional interfaces through a 3.5mm 4-pole plug. The first and third interfaces correspond to the right channel or video functional interfaces, respectively, and are used to output the right channel audio amplification signal or video signal according to the AV wiring sequence. The second interface corresponds to the left channel functional interface and is used to output the left channel audio amplification signal. The fourth interface is grounded.

[0019] Therefore, this utility model has the following beneficial effects: 1. This utility model switches the output interfaces of audio amplification signals and video signals by configuring the conduction path of the double-pole double-throw switch in the signal control wiring sequence switching circuit to adapt to AV cables with different wiring sequences. Compared with existing AV circuits that are only applicable to fixed wiring sequences, the circuit design of this utility model is universal, eliminating the need for customized design and production of circuit boards according to different wiring sequences. This improves product versatility and reduces the production and maintenance costs of products with different AV wiring sequences. At the same time, it eliminates the need for batch production and inventory management of AV cables with different wiring sequences, which helps to shorten the delivery cycle and improve market promotion efficiency.

[0020] 2. This utility model only requires setting the configuration signal according to the wiring sequence of different AV cables to realize the switching of the output interface of the right channel audio signal and video signal in the signal output circuit. There is no need to change the product bill of materials and other production data, eliminating the additional R&D, material, production and management costs brought about by maintaining multiple hardware versions for different regions, and realizing the standardized production and maintenance of the product.

[0021] 3. This utility model uses a low-impedance double-pole double-throw switch chip, which can effectively improve the isolation between the left and right channels and reduce crosstalk without significantly affecting the signal quality, thereby bringing additional audio performance improvement.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of AV lines with the line sequence 1234 (red, white, yellow, and ground) in the existing technology.

[0024] Figure 2 This is a schematic diagram of AV lines with the line sequence 1234 (yellow, white, red, and ground) in the existing technology.

[0025] Figure 3 This is a schematic diagram of a control circuit for switching AV line sequences provided in an embodiment of this utility model. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0027] An embodiment of a control circuit for switching AV line sequences See Figure 3 This utility model relates to a control circuit for switching AV line sequences, comprising an audio amplification circuit 10, a video output circuit 20, a line sequence selection circuit 30, and a signal output circuit 40. The audio amplification circuit 10 receives dual-channel audio signals AUDIO_DL and AUDIO_DR, amplifies these signals individually, and outputs an amplified audio signal AUDIO_OUT to the first set of switches in the line sequence selection circuit 30 and the second interface LOUT of the signal output circuit 40, respectively. The video output circuit 20 receives a video signal VDACOUT and transmits the video signal VDACOUT to the line sequence selection circuit 40. The second set of switches in circuit 30; the line sequence selection circuit 30 adopts a double-pole double-throw switch composed of the first set of switches and the second set of switches. The first set of switches and the second set of switches are respectively connected to the first interface CVBS of the signal output circuit 40 through the first common terminal D+ of the double-pole double-throw switch and connected to the third interface ROUT of the signal output circuit 40 through the second common terminal D- of the double-pole double-throw switch; the line sequence selection circuit 30 inputs a configuration signal CPU_CONTROL according to the AV line sequence. The configuration signal CPU_CONTROL is used to control the conduction path of the first set of switches and the second set of switches to switch the output interface of the audio amplification signal and the video signal.

[0028] Specifically, in this embodiment, the control circuit for switching AV line sequences is located in the digital TV set-top box, serving as the control unit for the analog audio and video output section of the set-top box. The digital TV set-top box also includes a main chip, which unpacks data packets containing audio and video signals, sending the separated audio data to an audio decoder and the separated video signal to a video decoder. After decoding and digital-to-analog conversion, the audio data outputs two analog audio signals, namely, dual-channel audio signals AUDIO_DL and AUDIO_DR, including a left channel analog audio signal and a right channel analog audio signal. After decoding, the video data outputs the video signal VDACOUT.

[0029] The main chip has multiple GPIO pins, and the corresponding configuration signal CPU_CONTROL is output through the GPIO pins according to the AV line sequence.

[0030] In this embodiment, the audio amplification circuit 10 includes an input stage circuit, an amplification stage circuit, and an output stage circuit. The input stage circuit receives the dual-channel audio signals AUDIO_DL and AUDIO_DR, and isolates the DC component in the dual-channel audio signals AUDIO_DL and AUDIO_DR through a first coupling capacitor CA4, so as to output an audio AC signal to the amplification stage circuit. The amplification stage circuit amplifies the audio AC signal and outputs an amplified audio signal AUDIO_OUT through the output stage circuit.

[0031] Specifically, in this embodiment, the first coupling capacitor CA4 is a 4.7nF, 6.3V surface mount capacitor.

[0032] Specifically, the input stage circuit also includes a resistor RA4 and a capacitor CA6. One end of the first coupling capacitor CA4 is connected to the dual-channel audio signals AUDIO_DL and AUDIO_DR, and the other end is connected to the base of the first transistor QA01 and one end of the capacitor CA6 through the resistor RA4. The other end of the capacitor CA6 is grounded. The capacitor CA6 is used to filter out high-frequency noise in the audio AC signal.

[0033] Specifically, the output stage circuit described in this embodiment includes at least a second coupling capacitor CA5. One end of the second coupling capacitor CA5 is connected to the drain of the first transistor QA01, and the other end outputs the audio amplification signal AUDIO_OUT, thereby reducing the impact of the subsequent stage circuit as a load on the DC environment and amplification of the first transistor QA01 under DC conditions.

[0034] In this embodiment, the amplification stage circuit includes a first resistor circuit, a second resistor circuit, a third resistor circuit, and a first transistor QA01. The base of the first transistor QA01 is connected to the audio AC signal and is connected to an external power supply 12V_IN through the first resistor circuit. Its drain is connected to an audio power supply 12V_AU through the second resistor circuit, and its source is grounded through the third resistor circuit. The first resistor circuit, the second resistor circuit, and the third resistor circuit are used to set the static operating point of the first transistor QA01 so that it operates in the amplification region.

[0035] Specifically, in this embodiment, the first resistor circuit includes resistors RA2 and RA5. The external power supply 12V_IN, after being filtered by the power supply filter circuit, is connected to the base of the first transistor QA01 through resistor RA2. Resistor RA5 is connected in parallel between the base and source of the first transistor QA01. The second resistor circuit includes at least resistor RA3, and the drain of the first transistor QA01 is connected to the audio power supply 12V_AU through resistor RA3. The third resistor circuit includes at least resistor RA6, and the source of the first transistor QA01 is grounded through resistor RA6.

[0036] In this embodiment, the amplification stage circuit further includes a power supply filter circuit. The power supply filter circuit adopts an RC filter network, including a first resistor RA1, a first capacitor CA11, and a second capacitor CA7. The first capacitor CA11 and the second capacitor CA7 are connected in parallel. One end is connected to an external power supply 12V_IN through the first resistor, and the other end is grounded.

[0037] The first capacitor is an electrolytic capacitor used to filter out low-frequency ripple; the second capacitor is used to filter out high-frequency noise.

[0038] Specifically, this embodiment uses an external power supply 12V_IN input. Since external DC power supplies usually have ripple and interference, the first capacitor CA11 is an electrolytic capacitor with a large capacity to filter out low-frequency noise and ripple and stabilize the power supply voltage; at the same time, the second capacitor CA7 is a ceramic capacitor with good high-frequency characteristics to filter out high-frequency noise.

[0039] Specifically, the audio amplifier circuit 10 described in this embodiment is only a preferred method for low-cost design. The above circuit can also be designed according to the requirements of the audio amplifier circuit 10, such as using an operational amplifier to amplify the audio signal, or using a bandpass filter to improve the filtering performance of the RC filter network.

[0040] In this embodiment, the line sequence selection circuit 30 includes a configuration circuit and a double-pole double-throw switch chip UA1 of model SGM7222. The configuration circuit is connected to the configuration signal CPU_CONTROL and is used to output a high level or a low level to the switch control pin of the double-pole double-throw switch chip UA1 according to the configuration signal CPU_CONTROL.

[0041] Specifically, in this embodiment, the SGM7222 chip is a high-performance double-pole double-throw switch chip UA1 with low insertion loss, good switching isolation, and short switching time. It has a bandwidth of 550MHz, and its switching on time is only 10ns and its switching off time is only 22ns, thereby ensuring that the audio and video signal VDACOUT is transmitted with almost no attenuation. It also has a high isolation of -35dB and crosstalk suppression of -41dB, thereby ensuring a high switching isolation.

[0042] Specifically, in this embodiment, the SGM7222 chip's switches are bidirectional for each channel, including 3 groups of 6 switch contacts: HSD1+, HSD2+, D+, D-, HSD1-, and HSD2-.

[0043] Specifically, the video output circuit 20 in this embodiment includes resistors RV55, R83, and RV56. One end of resistor RV55 is connected to the video signal VDACOUT, and is connected to one end of resistor RV56 and the switch contacts HSD1+ and HSD2- of the SGM7222 chip via resistor R83. The other ends of resistors RV55 and RV56 are both grounded. Resistor RV55 is used for impedance matching to ensure the integrity of the video signal; resistor RV56 is used to provide DC bias.

[0044] Specifically, in this embodiment, resistor RV55 is a 75R resistor with a precision of 1%, and resistor RV56 is a 100K resistor with a precision of 5%. Resistor R83 is a 0R resistor used for circuit debugging.

[0045] In this embodiment, the configuration circuit includes a second transistor QA2 and a current-limiting resistor R746. The base of the second transistor QA2 is connected to the configuration signal CPU_CONTROL through the current-limiting resistor R746. Its drain is connected to the chip power supply along with the power input pin of the double-pole double-throw switch chip UA1, and its source is grounded.

[0046] When the AV line sequence is 1, 2, 3, 4, corresponding to the right channel, left channel, video, and ground function interfaces respectively, the configuration signal CPU_CONTROL is set to a high level signal, which turns on the second transistor QA2.

[0047] When the AV line sequence is 1, 2, 3, 4, corresponding to the video, left channel, right channel, and ground function interfaces respectively, the configuration signal CPU_CONTROL is set to a low level signal, causing the second transistor QA2 to be cut off.

[0048] In this embodiment, the double-pole double-throw switch chip UA1 integrates the double-pole double-throw switch and is provided with the first knife switch connection contact HSD2+ and the second knife switch connection contact HSD1- of the first group of switches, and the third knife switch connection contact HSD1+ and the fourth knife switch connection contact HSD2- of the second group of switches.

[0049] When the second transistor QA2 is turned on, the switching control pin of the double-pole double-throw switch chip UA1 is at a low level. At this time, the second knife switch contact HSD1- is connected to the first common terminal D+, and the audio amplification signal AUDIO_OUT is output to the first interface CVBS. At the same time, the third knife switch contact HSD1+ is connected to the second common terminal D-, and the video signal VDACOUT is output to the third interface ROUT.

[0050] When the second transistor QA2 is turned off, the switching control pin of the double-pole double-throw switch chip UA1 is at a high level. At this time, the first knife switch contact HSD2+ is connected to the second common terminal D-, and the audio amplification signal AUDIO_OUT is output to the third interface ROUT. At the same time, the fourth knife switch contact HSD2- is connected to the first common terminal D+, and the video signal VDACOUT is output to the first interface CVBS.

[0051] In this embodiment, the signal output circuit 40 integrates the functional interfaces of right channel, left channel, video, and ground through a 3.5mm 4-pole plug. The first interface CVBS and the third interface ROUT correspond to the functional interfaces of the right channel or video, respectively, and are used to output the right channel audio amplification signal or video signal according to the AV line sequence. The second interface LOUT corresponds to the functional interface of the left channel and is used to output the left channel audio amplification signal. The fourth interface GND is grounded.

[0052] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.

Claims

1. A control circuit for switching AV line sequences, characterized in that, include: The system includes an audio amplification circuit, a video output circuit, a line sequence selection circuit, and a signal output circuit. The audio amplification circuit receives a dual-channel audio signal, amplifies the dual-channel audio signal in a single path, and outputs an amplified audio signal to the first set of switches in the line sequence selection circuit and the second interface of the signal output circuit. The video output circuit receives a video signal and transmits the video signal to the second set of switches in the line sequence selection circuit. The line sequence selection circuit uses a double-pole double-throw switch (DPNS) composed of the first set of switches and the second set of switches. The first set of switches and the second set of switches are connected to the first interface of the signal output circuit through the first common terminal of the DPNS and to the third interface of the signal output circuit through the second common terminal of the DPNS. The line sequence selection circuit inputs a configuration signal according to the AV line sequence. The configuration signal is used to control the conduction path of the first set of switches and the second set of switches to switch the output interfaces of the amplified audio signal and the video signal.

2. The control circuit for switching AV line sequences according to claim 1, characterized in that: The audio amplification circuit includes an input stage circuit, an amplification stage circuit, and an output stage circuit. The input stage circuit receives the dual-channel audio signal and isolates the DC component in the dual-channel audio signal through a first coupling capacitor to output an AC audio signal to the amplification stage circuit. The amplification stage circuit amplifies the AC audio signal and outputs the amplified audio signal through the output stage circuit.

3. A control circuit for switching AV line sequences according to claim 2, characterized in that: The amplification stage circuit includes a first resistor circuit, a second resistor circuit, a third resistor circuit, and a first transistor. The base of the first transistor is connected to the audio AC signal and is connected to an external power supply through the first resistor circuit. Its drain is connected to the audio power supply through the second resistor circuit, and its source is grounded through the third resistor circuit. The first resistor circuit, the second resistor circuit, and the third resistor circuit are used to set the static operating point of the first transistor so that it operates in the amplification region.

4. A control circuit for switching AV line sequences according to claim 3, characterized in that: The amplifier stage circuit also includes a power supply filter circuit. The power supply filter circuit adopts an RC filter network, including a first resistor, a first capacitor, and a second capacitor. The first capacitor and the second capacitor are connected in parallel. One end is connected to the external power supply through the first resistor, and the other end is grounded. The first capacitor is an electrolytic capacitor used to filter out low-frequency ripple; the second capacitor is used to filter out high-frequency noise.

5. A control circuit for switching AV line sequences according to claim 1, characterized in that: The line sequence selection circuit includes a configuration circuit and a double-pole double-throw switch chip of model SGM7222. The configuration circuit is connected to the configuration signal and is used to output a high level or a low level to the switch control pin of the double-pole double-throw switch chip according to the configuration signal.

6. A control circuit for switching AV line sequences according to claim 5, characterized in that: The configuration circuit includes a second transistor and a current-limiting resistor. The base of the second transistor is connected to the configuration signal through the current-limiting resistor. Its drain is connected to the chip power supply along with the power input pin of the double-pole double-throw switch chip, and its source is grounded. When the AV line sequence is 1, 2, 3, 4, corresponding to the right channel, left channel, video, and ground function interfaces respectively, the configuration signal is set to a high-level signal to turn on the second transistor. When the AV line sequence is 1, 2, 3, 4, corresponding to the video, left channel, right channel, and ground function interfaces respectively, the configuration signal is set to a low level signal, causing the second transistor to be cut off.

7. A control circuit for switching AV line sequences according to claim 6, characterized in that: The double-pole double-throw switch chip integrates the double-pole double-throw switch and is provided with the first knife switch connection contact point and the second knife switch connection contact point of the first group of switches, as well as the third knife switch connection contact point and the fourth knife switch connection contact point of the second group of switches. When the second transistor is turned on, the switching control pin of the double-pole double-throw switch chip is at a low level. At this time, the second knife switch contact is connected to the first common terminal, and the audio amplification signal is output to the first interface. At the same time, the third knife switch contact is connected to the second common terminal, and the video signal is output to the third interface. When the second transistor is cut off, the switching control pin of the double-pole double-throw switch chip is at a high level. At this time, the first knife switch contact point is connected to the second common terminal, and the audio amplification signal is output to the third interface. At the same time, the fourth knife switch contact point is connected to the first common terminal, and the video signal is output to the first interface.

8. A control circuit for switching AV line sequences according to any one of claims 1-7, characterized in that: The signal output circuit integrates right channel, left channel, video, and ground functional interfaces through a 3.5mm 4-pole plug. The first and third interfaces correspond to the right channel or video functional interfaces, respectively, and are used to output the right channel audio amplification signal or video signal according to the AV wiring sequence. The second interface corresponds to the left channel functional interface and is used to output the left channel audio amplification signal. The fourth interface is grounded.

Images