A piezoelectric and capacitive composite sensing vehicle door handle

Abstract

The utility model relates to a piezoelectric and capacitor composite sensing's car door outer handle, car, including sensing unit, piezoelectric measurement branch, capacitor digital conversion circuit, treater, sensing unit includes piezoelectric film and the upper electrode and lower electrode respectively arranged in the upper and lower two faces of piezoelectric film, the upper electrode is oriented handle and is away from the direction of car body, as the multiplexing electrode of piezoelectric film's signal output electrode and capacitor sensor's sensing electrode, capacitor sensor forms the electric field for sensing the electric field of external object approach and / or contact handle outer surface, piezoelectric measurement branch is coupled respectively upper and lower electrode to obtain the piezoelectric signal of vibration generation, piezoelectric measurement branch is provided with amplifier at least to amplify piezoelectric signal, capacitor digital conversion circuit is coupled upper electrode to obtain self -capacitance and / or mutual capacitance, processing module is coupled piezoelectric measurement branch, capacitor digital conversion circuit respectively.

Description

Technical Field

[0001] This utility model relates to the automotive field, and more particularly to a piezoelectric and capacitive composite sensing device for car door handles and automobiles. Background Technology

[0002] Modern smart cars have further upgraded their keyless entry systems. When the owner approaches the vehicle with the key, the vehicle will automatically sense this and prepare to unlock. At this point, the owner only needs to lightly touch the capacitive sensor button on the door handle to unlock the door, enjoying a more convenient and secure driving experience.

[0003] Capacitive touch buttons trigger operation by detecting human bioelectric signals (such as finger contact), and have the advantages of high sensitivity and fast response. However, in practical applications, they face the problem of false triggering, such as accidental activation when it rains or when washing a car, as well as accidental activation caused by large-area contact / shaking of the human body or metal objects.

[0004] JP2008248582A employs operation detection sensors, including a capacitive sensor that detects changes in capacitance of the door handle installed in the vehicle, and a vibration sensor that detects vibrations of the door handle or the vehicle itself. Through a combined capacitance and vibration detection mechanism, it accurately detects driver actions, minimizing environmental interference and significantly improving the door opening rate and false start rate. However, the dual sensors require independent installation and wiring, increasing the internal space occupied by the door handle and leading to structural complexity and cost. Utility Model Content

[0005] To address the shortcomings of existing technologies, a piezoelectric and capacitive composite sensing method for exterior door handles is proposed.

[0006] The exterior door handle of this utility model includes a sensing unit, a piezoelectric measurement branch, a capacitance-to-digital conversion circuit, and a processor. The sensing unit includes a piezoelectric film and upper and lower electrodes respectively disposed on the upper and lower surfaces of the piezoelectric film. The upper electrode faces the direction away from the vehicle body and serves as a multiplexed electrode for both the signal output electrode of the piezoelectric film and the sensing electrode of the capacitance sensor. The capacitance sensor forms an electric field for sensing the approach and / or contact of an external object with the outer surface of the handle. The piezoelectric measurement branch is coupled to the upper and lower electrodes to obtain the piezoelectric signal generated by vibration. The piezoelectric measurement branch is equipped with at least one amplifier to amplify the piezoelectric signal. The capacitance-to-digital conversion circuit is coupled to the upper electrode to obtain self-capacitance and / or mutual capacitance. The processing module is coupled to the piezoelectric measurement branch and the capacitance-to-digital conversion circuit.

[0007] The exterior door handle of this utility model also includes the following auxiliary technical solutions:

[0008] The upper electrode has several components, and each upper electrode forms or participates in forming at least three arrangements of self-capacitance induced electric fields and / or mutual capacitance induced electric fields.

[0009] Among them, one of the electric fields in the middle is the main electric field, and the other electric fields are auxiliary electric fields; the outer surface of the handle away from the vehicle body is the sensing area, and the outer surface of the handle in the sensing area is marked with a guide mark corresponding to the position of the main electric field.

[0010] The electric fields are arranged along the length of the handle.

[0011] In this configuration, each upper electrode has the same area and / or the spacing between each upper electrode is the same.

[0012] This includes a switch array, where the capacitor-to-digital converter circuit is coupled to each upper electrode via the switch array.

[0013] This includes a gating switch, which serves as a switching component for the upper electrode to connect the piezoelectric measurement branch and the capacitance digital conversion circuit in a time-division manner. The processing module is coupled to the gating switch.

[0014] The sensing unit is attached to the inner surface of the handle housing where the sensing area is located; or, there is a filler between the sensing unit and the handle housing where the sensing area is located.

[0015] Another vehicle is provided, including the aforementioned exterior door handle.

[0016] This utility model's exterior door handle, through the structural combination of piezoelectric and capacitive elements, improves the door opening rate and false trigger rate, and achieves the characteristics of compact sensor structure, controllable cost, strong capacitor stability, and high measurement sensitivity. Attached Figure Description

[0017] Figure 1 A cross-sectional view of the exterior door handle is provided.

[0018] Figure 2 A diagram showing the internal structure of the exterior door handle is provided.

[0019] Figure 3a A schematic diagram of the arrangement of three self-capacitance electric fields formed by the three upper electrodes is given. Figure 3b The diagram shows the first possible arrangement of the three mutual capacitance electric fields formed by the four upper electrodes. Figure 3c A schematic diagram of a second arrangement is given, in which the four upper electrodes form three mutual capacitance electric fields. Figure 3d A schematic diagram of the arrangement of multiple mutual capacitance electric fields formed by row and column electrodes is given. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0021] refer to Figure 1 , Figure 2 The door handle 100 has a built-in circuit board 200, which houses a sensing unit, a piezoelectric measurement branch, a capacitance-to-digital conversion circuit, and a processor.

[0022] The sensing unit includes a piezoelectric thin film 210, preferably a PVDF film, with electrodes distributed on both the upper and lower surfaces of the PVDF film. The upper electrode 220 is located on the top surface of the thin film 210 and serves as a combined electrode for both the signal output electrode of the piezoelectric thin film 210 and the sensing electrode of the capacitive sensor. The lower electrode 230 is located on the bottom surface of the thin film 210 and serves as the signal output electrode of the piezoelectric thin film 210. The outer surface of the handle 100 away from the vehicle body serves as the sensing area. The upper electrode 220 faces the handle 100 away from the vehicle body, and the capacitive sensor forms an electric field for sensing the approach and / or contact of external objects with the sensing area.

[0023] The piezoelectric measurement branch is coupled to the upper electrode 220 and the lower electrode 230 respectively to acquire the piezoelectric signal generated by vibration. The piezoelectric measurement branch includes an amplifier to amplify the piezoelectric charge. The capacitance-to-digital converter (CDC) uses Δ-Σ modulation to directly convert the measured capacitance value into a digital value by repeatedly charging and discharging the measured capacitor and comparing it with a reference capacitance (see US Patent Number: 5,134,401), improving the capacitance measurement sensitivity to the 1ff level. The capacitance-to-digital converter is coupled to the upper electrode 220 to acquire the self-capacitance and / or mutual capacitance of the upper electrode 220. The processing module is coupled to the piezoelectric measurement branch and the capacitance-to-digital converter.

[0024] In non-rainy conditions, machine detection primarily relies on capacitance changes caused by human hand proximity and / or contact. During rain, raindrops generate continuous vibrations of 100-500kHz, which the machine uses to identify rain. In this case, identification mainly relies on vibration; raindrops have low mass and weak vibration, while human hand contact causes mass changes, resulting in significant changes in vibration frequency and capacitance, thus distinguishing false triggers. By utilizing a composite structure of piezoelectric and capacitive elements, the sensor film 210 achieves ultra-thin thickness, keeping costs under control. Simultaneously, the dielectric between electrodes is changed from air or sponge to a piezoelectric material, improving capacitance stability. Furthermore, combined with the capacitance-to-digital conversion circuit's ability to capture subtle changes and eliminate stray capacitance interference, capacitance measurement sensitivity is high.

[0025] As an improvement, a plurality of electrodes are disposed on the top surface of the thin film 210, and each upper electrode 220 forms or participates in forming at least three arranged self-capacitance induced electric fields and / or mutual capacitance induced electric fields. As an exemplary electrode arrangement, Figure 3a A schematic diagram of the arrangement of three self-capacitance electric fields formed by the three upper electrodes 220 is given. Figure 3b The diagram shows a first arrangement of three mutual capacitance electric fields formed by the four upper electrodes 220. Figure 3cA second arrangement of three mutual capacitance electric fields formed by the four upper electrodes 220 is shown. Alternatively, a row-column scanning method can be used to form the electric field arrangement structure, such as... Figure 3d As shown, the row electrodes and column electrodes are separated by an insulating film, with the lower column electrodes located on the top surface of the piezoelectric film 210 as the upper electrode 220. By utilizing at least three arranged self-capacitance induced electric fields and / or mutual capacitance induced electric fields, directional changes such as raindrops, car washes, human bodies, or metal movement can be identified, achieving further differentiation and reducing the false trigger rate. More preferably, one of the electric fields in the middle serves as the main electric field, and the others serve as auxiliary electric fields. A guide marker 300 is provided on the outer surface of the handle 100 in the sensing area corresponding to the position of the main electric field. The ratio of capacitance change between the main and auxiliary electric fields formed by clicking the marker 300 differs from that in rainy weather, car washes, or when a large area of ​​a human body is close, further enhancing the prevention of accidental touch recognition.

[0026] In the improved design, the electric fields are arranged along the length of the handle 100 to sense whether the hand is horizontally approaching or rubbing from side to side. The areas of all upper electrodes 220 are the same and / or the spacing between them is the same, ensuring consistent capacitance changes. The electronic control system further incorporates a switch array. The capacitance-to-digital conversion circuit couples to each upper electrode 220 via the switch array, achieving a combination of self-capacitance and / or mutual capacitance switching. Depending on the scenario, this combination is based on the long-distance measurement characteristics of self-capacitance and the environmental anti-interference capabilities of mutual capacitance.

[0027] In another improved design, a gating switch is installed on handle 100. The processing module is coupled to the gating switch, which serves as a switching component for the upper electrode 220 to connect the piezoelectric measurement branch and the capacitance digital conversion circuit in a time-division manner, thereby avoiding signal crosstalk and improving reliability.

[0028] In this invention, to enhance vibration transmission, the sensing unit is attached to the inner surface of the handle 100 housing where the sensing area is located; or, there is a filler between the sensing unit and the handle 100 housing where the sensing area is located.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. A piezoelectric and capacitive composite sensing method for exterior door handles, characterized in that: Includes a sensing unit, a piezoelectric measurement branch, a capacitance-to-digital conversion circuit, and a processor; The sensing unit includes a piezoelectric film and an upper electrode and a lower electrode respectively disposed on the upper and lower surfaces of the piezoelectric film. The upper electrode faces the handle away from the vehicle body and serves as a multiplexed electrode for the signal output electrode of the piezoelectric film and the sensing electrode of the capacitive sensor. The capacitive sensor forms an electric field for sensing the approach and / or contact of an external object with the outer surface of the handle. The piezoelectric measurement branch is coupled to the upper and lower electrodes respectively to obtain the piezoelectric signal generated by vibration, and the piezoelectric measurement branch is provided with at least an amplifier to amplify the piezoelectric signal; The capacitance-to-digital conversion circuit is coupled to the upper electrode to obtain self-capacitance and / or mutual capacitance; The processing module is coupled to the piezoelectric measurement branch and the capacitance-to-digital conversion circuit, respectively.

2. The exterior door handle according to claim 1, characterized in that: The upper electrode has several components; Each upper electrode forms or participates in the formation of at least three arranged self-capacitance induced electric fields and / or mutual capacitance induced electric fields.

3. The exterior door handle according to claim 2, characterized in that: One of the electric fields located in the middle is designated as the main electric field, while the other electric fields are designated as auxiliary electric fields. The outer surface of the handle away from the vehicle body is used as the sensing area, and the outer surface of the handle in the sensing area is marked with a guide mark corresponding to the position of the main electric field.

4. The vehicle door handle of claim 2, wherein: Each of the electric fields is arranged along the length of the handle.

5. The vehicle door handle of claim 2, wherein: The areas of each upper electrode are the same and / or the spacing between each upper electrode is the same.

6. The vehicle door handle of claim 2, wherein: Includes a switch array, wherein the capacitor-to-digital converter circuit is coupled to each upper electrode through the switch array.

7. The exterior door handle according to claim 1, characterized in that: It includes a gating switch, which serves as a switching component for the upper electrode to connect the piezoelectric measurement branch and the capacitance digital conversion circuit in a time-division manner. The processing module is coupled to the gating switch.

8. The exterior door handle according to claim 1, characterized in that: The sensing unit is attached to the inner surface of the handle housing where the sensing area is located; Alternatively, there may be filler material between the sensing unit and the handle housing where the sensing area is located.

9. An automobile characterized by comprising: Includes the exterior door handle as described in any one of claims 1-8.

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