A POP sound elimination circuit and earphone with the circuit
By designing switchable differential and single-ended circuit modules in the headset, the problem of difficult POP sound in traditional headsets is solved, and the high-quality audio output of wireless headsets and the volume adjustment in wired mode is realized, which expands the usage scenario.
Patent Information
- Application Number
- CN202210344232.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-04-02
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2042-04-02
AI Technical Summary
The POP sound generated by traditional headphones during initialization is difficult to completely suppress, and the 3.5mm wired headphone mode in the prior art does not support volume adjustment, and although the differential output saves capacitance, it cannot achieve high-quality POP sound cancellation of wireless headphones.
A headphone output circuit that can switch between wireless and wired modes is designed, and a free switching module with differential and single-ended circuits is adopted. By detecting the sound source type, the circuit mode is automatically switched, avoiding the use of direct blocking capacitors, and efficient elimination of POP sound is achieved. .
It realizes high-quality POP sound cancellation in wireless headphones, saves capacitor costs, and supports the volume adjustment function of 3.5mm wired headphone mode, expanding the use scenarios of the headphones.
Smart Images
Figure CN114666701B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of audio processing, in particular to a POP sound elimination circuit and an earphone with the circuit. Background Art
[0002] In the process of initializing and closing the codec channel of the traditional headphone audio output, there is noise in the output channel, which is usually called POP sound. The reason is the popping sound caused by the transient impact brought by the initialization operation. Specifically, during the initialization of the headphone audio output, there is a Vbias enable process, which will produce a narrow sharp pulse transient impact and cause POP sound. In the prior art, the audio output modes of the headphone include single-ended two-channel output (unbalanced stero) and differential two-channel output (balanced stero). Among them, Figure 1 The single-ended headphone circuit shown in the figure has a DC voltage on the headphone output of the codec chip 1 (Audio codec / SOC). When the single-ended output is used, two 220uF DC isolation capacitors C3 and C4 are required for DC isolation. When the power is turned on and off, the large capacitor is charged and discharged, which introduces the common POP sound problem in the audio. Figure 3 Common audio POP sound elimination. When differential output is used, no additional large capacitor is required, which can save the cost of capacitors and POP sound elimination circuits. Figure 2 The differential headphone dual-channel output circuit is shown.
[0003] However, traditional POP sound suppression methods all require the use of DC blocking capacitors. The CODEC with an internal slow charging circuit controls the charging time of the DC blocking capacitor, which reduces the peak pulse amplitude on the DC blocking capacitor and slows down the rising edge, so the POP sound becomes smaller, but only reduces the POP sound, and does not completely suppress the POP sound; and in the existing technology, the 3.5mm wired headphone mode does not support the volume adjustment function. Summary of the invention
[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a headphone output circuit suitable for wireless (Bluetooth, 2.4G private protocol, 5.8G) headphones and supporting 3.5mm wired headphone mode, realizing sound source detection and free switching. The circuit solves the POP sound problem of wireless headphones, and also provides a headphone with free switching between differential circuit and single-ended circuit (unbalance-balance) and POP sound elimination circuit. It can realize free switching between single-ended circuit and differential circuit and improve the elimination effect of POP sound.
[0005] To achieve the above-mentioned purpose, the present invention provides a POP sound elimination circuit for headphone audio transmission, wherein the POP sound elimination circuit has a differential circuit and a single-ended circuit, and has a switching module that can switch between the differential mode and the single-ended mode, wherein the switching module includes a connecting socket, and when the headphone is in a wireless mode, the fifth contact and the sixth contact in the connecting socket are connected, and the seventh contact and the eighth contact are connected, thereby realizing a differential circuit; when the headphone is in a wired mode, the fifth contact and the sixth contact in the connecting socket are disconnected, and the seventh contact and the eighth contact are disconnected, thereby realizing a single-ended circuit.
[0006] Furthermore, when the headset works in wireless mode, the R+ end of the codec chip SOC is connected to the positive pole of the right speaker through the fifth contact and the sixth contact of the connecting socket, and the L+ end of the codec chip SOC is connected to the positive pole of the left speaker through the seventh contact and the eighth contact of the connecting socket.
[0007] Furthermore, the R-end of the codec chip SOC is connected to the cathode of the right speaker, and the L-end of the codec chip SOC is connected to the cathode of the left speaker.
[0008] Furthermore, due to the high level of GPIO1, the NPN transistor is turned on, the first N-MOS tube and the second N-MOS tube are turned off, and the negative electrodes of the left speaker and the right speaker are disconnected from the ground. At this time, the earphone works in a differential circuit.
[0009] Furthermore, when a wired audio source is inserted into the connector, the first contact and the second contact are mechanically disconnected, GPIO0 changes from a low level to a high level, the codec chip SOC detects that a wired audio source has been inserted, the codec chip SOC pulls down GPIO1, and at the same time turns off the board power supply, the NPN transistor is cut off, the first N-MOS tube and the second N-MOS tube are turned on, and the negative poles of the left and right speakers are connected to the ground. At this time, the headphones work in a single-ended circuit.
[0010] Furthermore, due to the insertion of the wired audio source, the fifth contact and the sixth contact, and the seventh contact and the eighth contact of the connector are mechanically disconnected, and the R+ and L+ ends of the codec chip SOC are disconnected from the positive electrodes of the left and right speakers. At this time, the earphone works in wired mode, realizing the switch from the differential circuit to the single-ended circuit.
[0011] Furthermore, the connection socket is a socket that can be inserted into a 3.5mm wired audio source, and the connection socket includes 8 contacts, namely a first contact, a second contact, a third contact, a fourth contact, a fifth contact, a sixth contact, a seventh contact and an eighth contact, wherein the first contact, the third contact, the fifth contact and the eighth contact are arranged on one side, and the second contact, the fourth contact, the sixth contact and the seventh contact are arranged on the other side; the first contact and the second contact have two states of conduction and disconnection, and the third contact and the fourth contact have two states of conduction and disconnection. The first contact and the second contact, the third contact and the fourth contact, the fifth contact and the sixth contact are connected, and the seventh contact and the eighth contact are connected; when the headset works in wireless mode, the first contact and the second contact, the third contact and the fourth contact, the fifth contact and the sixth contact are connected, and the seventh contact and the eighth contact are connected; in wired mode, the first contact and the second contact are mechanically disconnected, the third contact and the fourth contact are mechanically disconnected, the fifth contact and the sixth contact are mechanically disconnected, and the seventh contact and the eighth contact are also mechanically disconnected. Further, the third contact is connected to the R+ terminal of the codec chip SOC, the fifth contact is connected to the positive electrode of the right speaker, the fourth contact is connected to the L+ terminal of the codec chip SOC, and the sixth contact is connected to the positive electrode of the left speaker.
[0012] Furthermore, the R- and L-ends of the codec chip SOC are output and divided into two signals, one signal is connected to the cathode of the right speaker and the left speaker, and the other signal is output to the first N-MOS tube.
[0013] On the other hand, the present invention provides an earphone, in which the POP sound elimination circuit of the present invention is used.
[0014] According to the POP sound elimination circuit and earphone of the present invention, the earphone output circuit that can detect the sound source and switch freely can be realized. The POP sound problem of wireless earphones is solved by using the circuit. The earphone of the present invention has a differential circuit and a single-ended circuit (unbalance-balance) that can switch freely and a POP sound elimination circuit. The single-ended circuit and the differential circuit can be switched freely and the elimination effect of the POP sound can be improved. The wireless earphone can also realize the high-quality POP sound elimination function. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a schematic diagram of a single-ended earphone circuit in the prior art;
[0016] Figure 2 It is a schematic diagram of a headphone differential circuit in the prior art;
[0017] Figure 3 It is a schematic diagram of a POP sound elimination circuit in the prior art;
[0018] Figure 4This is a schematic diagram of the pop sound elimination circuit of this application;
[0019] Figure 5 This is a diagram of the internal mechanical structure of the headphone connector of this application;
[0020] Figure 6 This is a schematic diagram of the earphone structure of this application; DETAILED DESCRIPTION
[0021] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0022] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0024] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.
[0025] like Figure 4-Figure 6 As shown, the present invention provides a POP sound elimination circuit and an earphone having the circuit.
[0026] Based on the consideration of function and cost, the present invention designs a POP sound elimination circuit in the earphone with differential mode (balance stero) and single-ended mode (unbalance stero) detection and free switching, and its circuit structure is as follows: Figure 4As shown. When the headset works in wireless mode, the R+ end of the codec chip SOC is connected to the positive pole of the right speaker 101 through the fifth contact 5 and the sixth contact 6 of the connector 100, and the L+ end of the codec chip SOC is connected to the positive pole of the left speaker 102 through the eighth contact 8 and the seventh contact 7 of the connector. The R- end of the codec chip SOC is connected to the negative pole of the right speaker 101, and the L- end of the codec chip SOC is connected to the negative pole of the left speaker 102. Due to the high level of GPIO1, the NPN transistor Q6 is turned on, the first N-MOS tube Q4 and the second N-MOS tube Q5 are turned off, and the negative pole of the speaker is disconnected from the ground. At this time, the headset works in differential mode (balance stero), saving 2 large capacitors and there is no pop sound problem.
[0027] In wireless mode, the second contact of the connector is connected to the first contact, and GPIO0 is at a low level. When a 3.5mm wired audio source is inserted into the connector 100, the first contact and the second contact of the connector are mechanically disconnected, and GPIO0 is at a high level. The codec chip SOC detects the insertion of a wired audio source, and the codec chip SOC pulls down GPIO1, turns off the board power at the same time, and the NPN transistor Q6 is turned off. The first N-MOS tube Q4 and the second N-MOS tube Q5 are turned on, and the negative pole of the speaker is connected to the ground. At the same time, due to the insertion of the wired audio source, the fifth contact 5 and the sixth contact 6, the seventh contact 7 and the eighth contact 8 of the connector 100 are mechanically popped open, and the R+ and L+ ends of the codec chip SOC are disconnected from the positive poles of the left and right speakers. At this time, the headset works in a wired single-ended mode (unbalancestero), realizing the free switching of the differential circuit to the single-ended circuit.
[0028] Specifically, the connecting socket 100 is a socket that can be inserted into a 3.5mm wired audio source, and the connecting socket 100 includes eight contacts, namely a first contact 1, a second contact 2, a third contact 3, a fourth contact 4, a fifth contact 5, a sixth contact 6, a seventh contact 7 and an eighth contact 8, wherein the first contact 1, the third contact 3, the fifth contact 5 and the eighth contact 8 are arranged on one side, and the second contact 2, the fourth contact 4, the sixth contact 6 and the seventh contact 7 are arranged on the other side. When no wired audio source is inserted, the fifth contact 5 and the sixth contact 6 have two states, namely, on and off, and the seventh contact 7 and the eighth contact 8 have two states, namely, on and off; when the earphone works in wireless mode, the fifth contact 5 and the sixth contact 6 are connected, and the seventh contact 7 and the eighth contact 8 are connected; and when a wired audio source is inserted into the connector, the connection between the fifth contact 5 and the sixth contact 6 is mechanically disconnected, and the connection between the seventh contact 7 and the eighth contact 8 is also mechanically disconnected, thereby realizing free switching between differential circuits and single-ended circuits.
[0029] Among them, the fifth contact 5 is connected to the R+ end of the codec chip SOC, the sixth contact 6 is connected to the positive electrode of the right speaker 101, the eighth contact 8 is connected to the L+ end of the codec chip SOC, and the seventh contact 7 is connected to the positive electrode of the left speaker 102; the R-end of the codec chip SOC is divided into two signals after output, one signal is connected to the negative electrode of the right speaker 101, and the other signal is output to the first N-MOS transistor Q4. The signal through the first N-MOS transistor Q4 is divided into three paths, one is grounded, one is connected to VBAT through the resistor R4, and one is connected to the NPN transistor Q6; similarly, the L-end of the codec chip SOC is divided into two signals after output, one signal is connected to the negative electrode of the left speaker 102, and the other signal is output to the second N-MOS transistor Q5. The signal through the second N-MOS transistor Q5 is divided into three paths, one is grounded, one is connected to VBAT through the resistor R4, and one is connected to the NPN transistor Q6; the NPN transistor Q6 is also connected to GPIO1 through resistors R5 and R6. The function of resistor R6 is to provide an initial low level to the base of NPN transistor Q6, and the function of resistor R5 is to provide a base current to the base.
[0030] like Figure 5 As shown, it is a mechanical deconstruction diagram of the connection socket of the present application, including eight contacts, namely the first contact 1, the second contact 2, the third contact 3, the fourth contact 4, the fifth contact 5, the sixth contact 6, the seventh contact 7 and the eighth contact 8, wherein the first contact 1, the third contact 3, the fifth contact 5 and the eighth contact 8 are arranged on one side, and the second contact 2, the fourth contact 4, the sixth contact 6 and the seventh contact 7 are arranged on the other side. The first contact 1 and the second contact 2 are connected, corresponding to the microphone position of the 4-segment headphone line, the third contact 3 and the fourth contact 4 are connected, corresponding to the ground position of the 4-segment headphone line, the fifth contact 5 and the sixth contact 6 are connected, corresponding to the right channel position of the 4-segment headphone line, and the seventh contact 7 and the eighth contact 8 are connected, corresponding to the left channel position of the 4-segment headphone line. Since the present invention does not involve the function of the microphone, the microphone and the ground line are connected together to be compatible with the 3-segment headphone line.
[0031] like Figure 6 As shown, the earphone of the present invention has Figure 4 The earphones of the circuit shown can realize the free switching between wireless mode and wired mode, and can be connected to the audio output device by wireless or wired mode, thus expanding the use scenarios and applications of the earphones. And it can eliminate POP sound with maximum efficiency without using DC blocking capacitors.
[0032] PC and mobile phone are common audio output devices, and the interface form is 3.5mm single-ended dual-channel output. The earphone of the present invention can achieve the technical effect of effectively eliminating POP sound and improving sound quality, and can realize free switching between wired and wireless in a low-cost and high-efficiency manner.
[0033] For headphones and general handheld devices, the operating voltage will be between 0-vdd, so the common mode voltage of the audio signal is vdd / 2, that is, the audio will have a bias voltage. In single-ended circuits, capacitors are required to block DC and AC. In differential circuits, since the midpoint voltage of the two outputs is vdd / 2, capacitors are not required to block DC.
[0034] In the description of this specification, the description with reference to the terms "embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. In addition, those skilled in the art can combine or combine different embodiments or examples described in this specification and the features therein without causing any contradiction.
[0035] Although the above content has shown and described the embodiments of the present invention, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace, modify and other update operations on the above embodiments within the scope of the present invention.
Claims
1. A POP sound elimination circuit for headphone audio transmission, characterized in that: The POP sound elimination circuit has a differential circuit and a single-ended circuit, and has a switching module that can switch between the differential mode and the single-ended mode. The switching module includes a connection socket. When the headset is in a wireless mode, the fifth contact and the sixth contact in the connection socket are connected, and the seventh contact and the eighth contact are connected to realize a differential circuit; when the headset is in a wired mode, the fifth contact and the sixth contact in the connection socket are disconnected, and the seventh contact and the eighth contact are disconnected to realize a single-ended circuit. Among them, the fifth contact is connected to the R+ end of the codec chip SOC, the sixth contact is connected to the positive electrode of the right speaker, the eighth contact is connected to the L+ end of the codec chip SOC, and the seventh contact is connected to the positive electrode of the left speaker; the R- end of the codec chip SOC is divided into two signals after output, one signal is connected to the negative electrode of the right speaker, and the other signal is output to the first N-MOS tube Q4. The signal through the first N-MOS tube Q4 is divided into three paths, one is grounded, one is connected to VBAT through the resistor R4, and one is connected to the NPN transistor Q6; the L- end of the codec chip SOC is divided into two signals after output, one signal is connected to the negative electrode of the left speaker, and the other signal is output to the second N-MOS tube Q5. The signal through the second N-MOS tube Q5 is divided into three paths, one is grounded, one is connected to VBAT through the resistor R4, and one is connected to the NPN transistor Q6; the NPN transistor Q6 is also connected to GPIO1 through resistors R5 and R6.
2. The POP sound elimination circuit according to claim 1, characterized in that: When the headset works in wireless mode, the R+ end of the codec chip SOC is connected to the positive pole of the right speaker through the fifth and sixth contacts of the connecting socket, and the L+ end of the codec chip SOC is connected to the positive pole of the left speaker through the seventh and eighth contacts of the connecting socket.
3. The POP sound elimination circuit according to claim 2, characterized in that: The R-end of the codec chip SOC is connected to the cathode of the right speaker, and the L-end of the codec chip SOC is connected to the cathode of the left speaker.
4. The POP sound elimination circuit according to claim 3, characterized in that: Due to the high level of GPIO1, the NPN transistor is turned on, the first N-MOS tube and the second N-MOS tube are turned off, and the negative poles of the left and right speakers are disconnected from the ground. At this time, the earphone works in a differential circuit.
5. The POP sound elimination circuit according to claim 4, characterized in that: When a wired audio source is plugged into the connector, the codec chip SOC detects that GPIO0 is pulled high, the codec chip SOC pulls GPIO1 low, and at the same time turns off the board power, the NPN transistor is cut off, the first N-MOS tube and the second N-MOS tube are turned on, and the negative poles of the left and right speakers are connected to the ground. At this time, the headphones work in a single-ended circuit.
6. The POP sound elimination circuit according to claim 5, characterized in that: Due to the insertion of a wired audio source, the first contact and the second contact, the third contact and the fourth contact, the fifth contact and the sixth contact, and the seventh contact and the eighth contact of the connector are mechanically disconnected, and the R+ and L+ ends of the codec chip SOC are disconnected from the positive poles of the left and right speakers; at this time, the earphones work in wired mode, realizing the switching of the differential circuit to the single-ended circuit.
7. The POP sound elimination circuit according to claim 1, characterized in that: The connector is a socket that can be inserted into a 3.5mm wired audio source. The connector includes 8 contacts, namely the first contact, the second contact, the third contact, the fourth contact, the fifth contact, the sixth contact, the seventh contact and the eighth contact. The first contact, the third contact, the fifth contact and the eighth contact are arranged on one side, and the second contact, the fourth contact, the sixth contact and the seventh contact are arranged on the other side; the first contact and the second contact have two states of conduction and disconnection, the third contact and the fourth contact have two states of conduction and disconnection, There are two states between the fifth contact and the sixth contact, and there are two states between the seventh contact and the eighth contact; when the headset works in wireless mode, the first contact and the second contact, the third contact and the fourth contact, the fifth contact and the sixth contact are conductive, and the seventh contact and the eighth contact are conductive; in wired mode, the first contact and the second contact are mechanically disconnected, the third contact and the fourth contact are mechanically disconnected, the fifth contact and the sixth contact are mechanically disconnected, and the seventh contact and the eighth contact are also mechanically disconnected.
8. A headset, characterized in that: The earphone has the POP sound elimination circuit described in any one of claims 1 to 7.