Flexible printed circuit (FPC) and earphone
By employing a touch structure, simulated ground layer, and isolation layer design within the FPC flexible circuit board, the problem of balancing touch and radio frequency functions in TWS earphones within a limited volume is solved, achieving non-interference between functions and cost savings.
Patent Information
- Application Number
- CN202520371459.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2026-03-03
- Estimated Expiration
- 2035-03-04
AI Technical Summary
Existing TWS earphones struggle to balance touch control and radio frequency functions within a limited size, and the two are prone to interference, resulting in unsatisfactory control or poor antenna performance.
The design employs an FPC flexible circuit board, which includes a touch structure, a simulated ground layer, and an isolation layer. The isolation layer covers the first side of the simulated ground layer and is set parallel to the inner surface of the touch structure to prevent direct contact. The simulated ground layer serves as a radio frequency antenna structure, and the touch structure and the simulated ground layer together radiate electromagnetic waves.
This achieves independent operation of touch control and RF antenna functions, reducing the space and cost of designing a separate RF antenna and enhancing the headphone's market competitiveness.
Smart Images
Figure CN223967947U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic equipment technology, and in particular to an FPC flexible printed circuit board and headphones. Background Technology
[0002] In the current technology, all True Wireless Stereo (TWS) earbuds have touch control functions. The corresponding touch control circuits are basically located on the outside of the TWS earbuds to facilitate finger touch sensing. However, the earbud antenna also needs to be placed on the outside of the earbuds for good antenna performance.
[0003] As market demands change, the size of headphones needs to be reduced, but to ensure a better touch control experience, the touch control circuitry and radio frequency circuitry need to be designed to be relatively large, creating a contradiction. Furthermore, these two types of functional circuitry are prone to interference, which can easily lead to unsatisfactory control effects or antenna performance. Utility Model Content
[0004] The main purpose of this application is to provide an FPC flexible printed circuit board and an earphone, which aims to solve the technical problem of how to balance touch control and radio frequency functions within the limited size of the earphone.
[0005] To achieve the above objectives, this application provides an FPC flexible printed circuit board, which includes: a touch structure, a simulated ground layer, and an isolation layer;
[0006] An isolation layer covers the first surface of the simulated ground layer, which is set parallel to the inner surface of the touch structure.
[0007] An isolation layer is used to prevent the touch-sensitive structure from directly contacting the simulated geological formation;
[0008] The simulated ground layer serves as a radio frequency antenna structure, and the touch structure radiates electromagnetic waves together with the simulated ground layer.
[0009] This application also provides an FPC flexible printed circuit board and an earphone. The FPC flexible printed circuit board includes: a touch structure, an analog ground layer, and an isolation layer; the isolation layer covers the first surface of the analog ground layer, and the first surface of the analog ground layer is arranged parallel to the inner surface of the touch structure; the isolation layer is used to prevent the touch structure from directly contacting the analog ground layer; wherein, the analog ground layer serves as a radio frequency antenna structure, and the touch structure and the analog ground layer together radiate electromagnetic waves.
[0010] In a Flexible Printed Circuit (FPC), an isolation layer physically isolates the touch structure from the simulated ground layer. This double-layer protection effectively prevents abnormal touch functionality caused by interference from other abnormal electrical signals on the inner surface of the touch structure. Simultaneously, because the touch structure and the simulated ground layer are arranged parallel to each other, and the simulated ground layer is an independent good conductor, it can function as a radio frequency (RF) antenna. In this structure, the touch function and the RF antenna function do not interfere with each other, and the RF antenna function can be implemented using the simulated ground layer, reducing the circuit structure required for the RF antenna function. This allows the FPC to simultaneously implement touch and RF antenna functions, saving space and cost associated with designing a separate RF antenna. Attached Figure Description
[0011] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0013] Figure 1 This is a structural schematic diagram of an embodiment of the FPC flexible circuit board of this application;
[0014] Figure 2 This is a partial structural diagram of the FPC flexible circuit board of this application;
[0015] Figure 3 This is a structural schematic diagram of the first embodiment of the earphone in this application;
[0016] Figure 4 This is an equivalent circuit diagram of the RF antenna matching circuit and the touch matching circuit of this application.
[0017] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0018] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.
[0019] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.
[0020] This application proposes an FPC flexible printed circuit board, please refer to... Figure 1The FPC flexible circuit board includes: a touch structure 2, a simulated ground layer 3, and an isolation layer 6;
[0021] The isolation layer 6 covers the first surface of the simulated ground layer 3, and the first surface of the simulated ground layer 3 is set parallel to the inner surface of the touch structure 2.
[0022] The isolation layer 6 is used to prevent the touch structure 2 from directly contacting the simulated geological formation 3;
[0023] The simulated ground layer 3 serves as a radio frequency antenna structure, and the touch structure 2 radiates electromagnetic waves together with the simulated ground layer 3.
[0024] It should be noted that in this embodiment, the touch structure 2, the simulated ground layer 3, and the isolation layer 6 are all sheet-like structures. The touch structure 2 contains touch circuitry, and its outer surface can be selected as the touch surface to collect low-frequency electrical signals generated by finger touches, i.e., touch signals. These signals are then transmitted to the headphone's mainboard 7 via the touch circuitry to achieve the touch function. The simulated ground layer 3 does not directly contact the touch structure 2; that is, there is no direct electrical connection between them. It can be made of a metal with excellent conductivity. The conductor is mainly used to provide an analog ground for the touch structure 2, shield other interference signals transmitted on the motherboard 7 of the headphone, and ensure the accuracy of the touch signal sent from the touch structure 2 to the motherboard 7; the isolation layer 6 covers the first surface of the analog ground layer 3, and the first surface of the analog ground layer 3 is set parallel to the inner surface of the touch structure 2. It can also be understood that the isolation layer 6 physically isolates the inner surface of the touch structure 2 from the first surface of the analog ground layer 3. The isolation layer 6 can be made of insulating material to prevent electrical connection between the analog ground layer 3 and the touch structure 2.
[0025] It is worth noting that in this embodiment, the surface area of the simulated ground layer 3 can be larger than the surface area of the touch structure 2. As a radio frequency antenna structure, the simulated ground layer 3 can adjust its area and shape according to the antenna design requirements.
[0026] Furthermore, the isolation layer 6 includes: isolation material;
[0027] An insulating material is filled between the simulated ground layer 3 and the touch structure 2 to fix the simulated ground layer 3 and the touch structure 2 and to physically isolate them.
[0028] It is worth noting that in this embodiment, please refer to... Figure 2To understand this, the isolation layer 6 can be made of an insulating material with good insulation and adhesion, specifically an insulating adhesive. Both sides of the isolation layer 6 are tightly attached to the first surface of the simulated ground layer 3 and the inner surface of the touch structure 2, respectively. Alternatively, the isolation material can be understood as completely filling the space between the simulated ground layer 3 and the touch structure 2, thus effectively preventing electrical connections between them. Furthermore, due to the adhesive properties of the insulating material, after curing, it can firmly fix the simulated ground layer 3 and the touch structure 2 together, ensuring a relatively stable distance between them—that is, a predetermined fixed distance between them.
[0029] It is easy to understand that in this embodiment, since the touch structure 2 needs to be equipped with touch circuitry for transmitting low-frequency electrical signals, it must necessarily be a conductor with excellent conductivity. The simulated ground layer 3 is also a conductor with excellent conductivity and is relatively independently arranged. When both are sheet-like structures and arranged parallel to each other, it can be considered as two dielectric substrates arranged parallel to each other at a fixed distance. The simulated ground layer 3 can be used as a radio frequency antenna; correspondingly, the touch structure 2 is also a good conductor and can radiate electromagnetic waves together with the simulated ground layer 3. The specific form of the double-layer structure design formed by the touch structure 2 and the simulated ground layer 3 is not specifically limited.
[0030] The FPC flexible board formed based on the above structure to realize touch and radio frequency functions can reduce the structural space and cost of the antenna part that originally needed to be set separately because it can simulate ground layer 3 as radio frequency antenna. This is in line with the development trend of the headphone market and can easily enhance market competitiveness.
[0031] This application proposes an FPC (Flexible Printed Circuit) board, which includes a touch structure, an analog ground layer, and an isolation layer. In the FPC board, the touch structure and the analog ground layer are physically isolated by the isolation layer. This double-layer protection of the analog ground layer and the isolation layer effectively prevents abnormal touch functionality caused by interference from other abnormal electrical signals on the inner surface of the touch structure. Simultaneously, since the touch structure and the analog ground layer are arranged parallel to each other, and the analog ground layer is an independent good conductor, it can serve as a radio frequency (RF) antenna, realizing RF antenna functionality. In this structure, the touch function and the RF antenna function do not interfere with each other, and the RF antenna function can be implemented using the analog ground layer, reducing the circuit structure used to implement the RF antenna function. This allows the FPC board to simultaneously implement touch and RF antenna functions, saving space and cost associated with designing a separate RF antenna.
[0032] Furthermore, to achieve the above objectives, this application also proposes an earphone, please refer to... Figure 1 , Figure 3 as well as Figure 4The headphones include: motherboard 7 and the aforementioned FPC flexible board;
[0033] The motherboard 7 is equipped with an RF antenna matching circuit 42, a touch matching circuit 41, an RF chip 402, and a touch chip 401.
[0034] The RF antenna matching circuit 42 is electrically connected to the RF chip 402 and the simulated ground layer 3 of the FPC flexible board, and the touch matching circuit 41 is electrically connected to the touch chip 401 and the touch structure 2 of the FPC flexible board.
[0035] The radio frequency antenna matching circuit 42 is used to transmit high-frequency electrical signals between the radio frequency chip 402 and the simulated ground layer 3.
[0036] The touch matching circuit 41 is used to transmit low-frequency electrical signals between the touch chip 401 and the touch structure 2.
[0037] It should be noted that in this embodiment, the motherboard 7 refers to the core circuit board inside the earphone used to implement control functions. It integrates various functional devices or circuits, such as a Bluetooth circuit, an RF chip 402, a touch chip 401, an RF antenna matching circuit 42, and a touch matching circuit 41. Among these, the touch chip 401 and the RF chip 402 are the core devices for implementing their respective functions, and are only used in... Figure 4 The equivalent circuit is shown; the touch matching circuit 41 is disposed between the touch structure 2 and the touch chip 401 of the FPC flexible board, and is used to perform low-pass filtering on the low-frequency electrical signal transmitted between the touch structure 2 and the touch chip 401 (which can be understood as the touch signal formed by the touch structure 2 detecting finger touch), thereby ensuring that the low-frequency electrical signal received by the touch chip 401 is more accurate; the radio frequency antenna matching circuit 42 is disposed between the analog ground layer 3 of the FPC flexible board and the touch chip 401, and is used to perform impedance matching on the high-frequency electrical signal transmitted between the analog ground layer 3 (which can be understood as the antenna structure) and the touch chip 401 (which can be understood as the radio frequency signal sent by the radio frequency chip 402 to the antenna structure or the radio frequency signal transmitted by the antenna structure to the radio frequency chip 402), thereby ensuring the effective transmission of the high-frequency electrical signal transmitted and received by the radio frequency chip 402.
[0038] It is worth noting that the simulated ground plane 3 is an independent good conductor and can be used as a radio frequency antenna. The touch structure 2 is also a good conductor, allowing the touch structure 2 and the simulated ground plane 3 to radiate or receive electromagnetic waves together. In this embodiment, an antenna spring 1 is also provided between the radio frequency antenna matching circuit 42 of the motherboard 7 and the simulated ground plane 3. The antenna spring 1 is conductive and can undergo elastic deformation. When the distance between the touch structure 2 and the simulated ground plane 3 is too close, the touch structure 2 can be automatically reset, allowing the user to repeatedly touch the screen. Furthermore, based on the conductivity of the antenna spring 1, it can also cooperate with the radio frequency antenna matching circuit 42 to allow the high-frequency electrical signals generated by the radio frequency chip 402 on the motherboard 7 to be transmitted to the simulated ground plane 3 through the antenna spring 1 and the radio frequency antenna matching circuit 42.
[0039] Furthermore, in this embodiment, the earphone also includes: a connector for the ribbon cable 8;
[0040] The connector 8 is fixed to the motherboard 7 and electrically connected to the touch structure 2 and the touch matching circuit 41.
[0041] It should be noted that, in this embodiment, to ensure a stable electrical connection between the touch structure 2 and the motherboard 7, a connector 8 can be fixed on the motherboard 7 to connect the touch matching circuit 41. The connector 8 can be a surface mount type, a through-hole type, or other designs, without specific limitations. As a preferred option, it can be a board-to-board (BTB) connector. The touch structure 2 can be connected to the connector 8 through the corresponding connection structure, enabling the touch structure 2 to establish a stable electrical connection with the touch matching circuit 41 on the motherboard 7, thereby allowing the touch chip 401 to receive a more stable and accurate low-frequency electrical signal (touch signal).
[0042] Furthermore, in this embodiment, the earphone also includes: a bracket 5;
[0043] One side of bracket 5 is used to fix the simulated ground layer 3 of the FPC flexible board, and the other side of bracket 5 is used to fix the motherboard 7.
[0044] It should be noted that the bracket 5 is non-conductive and can be fixed inside the earphone shell. One side is used to fix the FPC flexible circuit board, which can be directly connected to the analog ground layer 3. The other side is used to fix the main board 7, thereby keeping the earphone shell, FPC flexible circuit board, and main board 7 relatively stationary. Its structure from the outside to the inside can be: earphone shell, touch structure 2, isolation layer 6, analog ground layer 3, bracket 5, and main board 7. When the earphone is shaken or bumped, it can effectively prevent the earphone shell from colliding with the FPC flexible circuit board or main board 7 and causing damage to the internal structure of the earphone, thus improving the reliability of the earphone.
[0045] In specific implementation, it can be combined with Figure 4 To understand this, the RF antenna matching circuit 42 can be two Π-shaped networks formed by a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1, and a second inductor L2. The first end of the first inductor L1 is connected to the antenna spring 1 and the first end of the first capacitor C1. The second end of the first inductor L1 is connected to the first ends of the second capacitor C2, the third capacitor C3, and the second inductor L2, respectively. The second end of the second inductor L2 is connected to the first end of the fourth capacitor C4 and the RF transceiver terminal of the RF chip 402. The second ends of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are all grounded. The touch matching circuit 41 can be a low-pass filter circuit formed by the third inductor L3 and the first resistor R1. The first end of the third inductor L3 is connected to the connector 8. The second end of the third inductor L3 is connected to the first end of the first resistor R1. The second end of the first resistor R1 is connected to the touch receiver terminal of the touch chip 401. The form of the matching circuit is not limited, and other filtering devices can also be used instead.
[0046] In a specific scenario, when a user plays music from their mobile phone through headphones, the simulated ground layer 3 (antenna structure) of the FPC flexible board can transmit and receive electromagnetic waves with the mobile phone; when the user touches the device, the user can touch the touch surface on the headphones (the touch surface or outer surface of the touch structure 2), thereby causing the touch structure 2 to generate a corresponding touch signal. The touch signal is then low-pass filtered by the touch matching circuit 41 of the motherboard 7 and transmitted to the touch chip 401.
[0047] This application provides an earphone, which includes an FPC flexible circuit board and a motherboard. Since the FPC flexible circuit board is used, it has at least all the technical features of all the above-mentioned FPC flexible circuit board embodiments, which will not be repeated here. It can solve the technical problem of how to take into account both touch function and radio frequency function within the limited size of the earphone.
[0048] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.
Claims
1. An FPC flexible board characterized by, The FPC soft board comprises a touch structure, an analog ground layer and an isolation layer. The isolation layer covers a first surface of the analog ground layer, and the first surface of the analog ground layer is parallel to an inner surface of the touch structure. The isolation layer is used to prevent the touch structure from directly contacting the analog ground layer. The analog ground layer serves as a radio frequency antenna structure, and the touch structure radiates electromagnetic waves together with the analog ground layer.
2. The FPC soft board according to claim 1, wherein, The isolation layer comprises an isolation material. The isolation material is filled between the analog ground layer and the touch structure, and is used to fix and physically isolate the analog ground layer and the touch structure.
3. The FPC soft board according to claim 1, wherein, The surface area of the analog ground layer is greater than the area of the touch structure.
4. An earphone, characterized by The earphone comprises a main board and the FPC soft board according to any one of claims 1-3. The main board is provided with a radio frequency antenna matching circuit, a touch matching circuit, a radio frequency chip and a touch chip. The radio frequency antenna matching circuit is electrically connected with the radio frequency chip and the analog ground layer of the FPC soft board, and the touch matching circuit is electrically connected with the touch chip and the touch structure of the FPC soft board. The radio frequency antenna matching circuit is used to transmit high-frequency electric signals between the radio frequency chip and the analog ground layer. The touch matching circuit is used to transmit low-frequency electric signals between the touch chip and the touch structure.
5. The earphone of claim 4, wherein The low-frequency electric signals comprise touch signals generated by the touch structure due to the outer surface being touched by a finger.
6. The earphone of claim 4, wherein The high-frequency electric signals comprise radio frequency signals transmitted from the analog ground layer to the radio frequency antenna matching circuit and radio frequency signals transmitted from the radio frequency antenna matching circuit to the analog ground layer.
7. The earphone of claim 4, wherein The earphone further comprises an antenna spring. The antenna spring is arranged between the analog ground layer and the main board, and is electrically connected with the analog ground layer and the radio frequency antenna matching circuit. The antenna spring is used to transmit high-frequency electric signals between the radio frequency antenna matching circuit and the analog ground layer.
8. The earphone of claim 4, wherein The earphone further comprises a connection flat cable seat. The connection flat cable seat is fixed on the main board, and is electrically connected with the touch structure and the touch matching circuit.
9. The earphone of claim 4, wherein The earphone further comprises a bracket. One surface of the bracket is used to fix the analog ground layer of the FPC soft board, and the other surface of the bracket is used to fix the main board.