Piezoelectric transducer and pressure sensing key

Abstract

The present invention provides a piezoelectric transducer. The piezoelectric transducer comprises a sheet-shaped piezoelectric ceramic, and an upper elastic piece and a lower elastic piece which are respectively arranged on two opposite sides of the piezoelectric ceramic; two ends of the upper elastic piece are respectively fixed to the upper surface of the piezoelectric ceramic, and at least part of the upper elastic piece is spaced apart from the piezoelectric ceramic; two ends of the lower elastic piece are respectively fixed to the lower surface of the piezoelectric ceramic, and at least part of the lower elastic piece is spaced apart from the piezoelectric ceramic. The piezoelectric transducer further comprises a plurality of resistance layers fixed to each of the upper elastic piece and the lower elastic piece, and the plurality of resistance layers are electrically connected to each other to form a bridge structure. Compared with the related art, the piezoelectric transducer of the present invention can identify, by means of resistance change, external force borne by the pressure sensing key, thereby achieving pressure change detection.

Description

Piezoelectric transducer and pressure-sensitive buttons Technical Field

[0001] The present invention relates to a key device, and in particular to a piezoelectric transducer and a pressure-sensitive key. Background Art

[0002] Piezoelectric ceramics are a type of electronic ceramic material with piezoelectric properties. Currently, related technologies include using piezoelectric ceramic devices in components such as buttons in electronic products like mobile phones and watches, enabling sensing and vibration functions. This has achieved excellent user experience and market response. These piezoelectric ceramic devices primarily employ bow-shaped and cymbal-shaped transducer structures. Technical issues

[0003] However, the related art uses piezoelectric ceramic components for keypads, where the transducer structure consists of two upper and lower bow-shaped or cymbal-shaped metal structures bonded to the piezoelectric ceramic sheet with glue. However, the current transducer structure is insufficient for constant force detection, making it impossible to detect pressure changes to identify gestures such as sliding, pressing, and positioning.

[0004] Therefore, it is necessary to provide a new piezoelectric transducer and pressure-sensitive button to solve the above problems. Technical Solutions

[0005] The technical problem to be solved by the present invention is to provide a piezoelectric transducer and a pressure-sensitive key capable of detecting pressure changes.

[0006] To solve the above technical problems, in a first aspect, the present invention provides a piezoelectric transducer, comprising a sheet-shaped piezoelectric ceramic, an upper spring sheet and a lower spring sheet respectively disposed on opposite sides of the piezoelectric ceramic; the ends of the upper spring sheet are respectively fixed to the upper surface of the piezoelectric ceramic, and the upper spring sheet is at least partially spaced from the piezoelectric ceramic; the ends of the lower spring sheet are respectively fixed to the lower surface of the piezoelectric ceramic, and the lower spring sheet is at least partially spaced from the piezoelectric ceramic;

[0007] The piezoelectric transducer further includes a plurality of resistance layers respectively fixed to the upper spring sheet and the lower spring sheet, and the plurality of resistance layers are electrically connected to each other to form a bridge structure.

[0008] Preferably, the upper spring plate includes a first base portion located on the upper surface of the piezoelectric ceramic and spaced apart from the piezoelectric ceramic, a first bent portion and a second bent portion extending obliquely from both ends of the first base portion toward both ends of the piezoelectric ceramic, and a first fixing portion and a second fixing portion extending from the first bent portion and the second bent portion and fixed to the piezoelectric ceramic respectively.

[0009] The lower spring plate includes a second base portion located on the lower surface of the piezoelectric ceramic and spaced apart from the piezoelectric ceramic, a third bent portion and a fourth bent portion extending obliquely from two ends of the second base portion toward two ends of the piezoelectric ceramic, and a third fixing portion and a fourth fixing portion extending from the third bent portion and the fourth bent portion respectively and fixed to the piezoelectric ceramic;

[0010] The resistor layers include four, and are respectively adhered and fixed to the first bending portion, the second bending portion, the third bending portion, and the fourth bending portion. The four resistor layers are connected via an FPC.

[0011] Preferably, the four resistance layers are connected to form a Wheatstone bridge structure.

[0012] Preferably, the resistance layer is a varistor.

[0013] Preferably, the plurality of resistance layers are respectively attached to a side of the first bending portion, the second bending portion, the third bending portion and the fourth bending portion away from the piezoelectric ceramic.

[0014] Preferably, the first fixing portion and the second fixing portion of the upper spring piece are fixed to the piezoelectric ceramic via an adhesive layer.

[0015] Preferably, the third fixing portion and the fourth fixing portion of the lower elastic sheet are fixed to the piezoelectric ceramic via an adhesive layer.

[0016] In a second aspect, the present invention also provides a pressure-sensitive button, comprising a shell, a piezoelectric transducer as described in any one of the above items housed in the shell, and a button bar covered on the shell and covering the piezoelectric transducer, the upper spring sheet abutting against the button bar, and the lower spring sheet abutting against the shell. Beneficial effects

[0017] Compared with the related art, the piezoelectric transducer of the present invention includes a sheet-shaped piezoelectric ceramic, an upper spring sheet and a lower spring sheet respectively arranged on opposite sides of the piezoelectric ceramic; the two ends of the upper spring sheet are respectively fixed to the upper surface of the piezoelectric ceramic, and the upper spring sheet is at least partially spaced from the piezoelectric ceramic; the two ends of the lower spring sheet are respectively fixed to the lower surface of the piezoelectric ceramic, and the lower spring sheet is at least partially spaced from the piezoelectric ceramic; the piezoelectric transducer also includes a plurality of resistor layers respectively fixed to the upper spring sheet and the lower spring sheet, and the plurality of resistor layers are electrically connected to each other to form a bridge structure. In the above structure, the bent portion of the spring sheet will contract and deform when subjected to pressure, and the deformation will cause the resistor layer to deform. Since the resistance value of the resistor layer will change linearly under deformation, the external force applied to the pressure-sensing key can be identified by the resistance change, thereby realizing pressure change detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0019] FIG1 is a schematic diagram of the three-dimensional structure of a piezoelectric transducer of the present invention;

[0020] FIG2 is a schematic diagram of the overall exploded structure of the piezoelectric transducer of the present invention;

[0021] FIG3 is a cross-sectional view along line AA in FIG1 ;

[0022] FIG4 is a schematic diagram of the three-dimensional structure of a pressure-sensitive button according to the present invention;

[0023] FIG5 is an enlarged view of part B in FIG4 . Best Mode for Carrying Out the Invention

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention 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 making creative efforts are within the scope of protection of the present invention.

[0025] Example 1

[0026] 1-3 , the present invention provides a piezoelectric transducer 100, comprising a sheet-shaped piezoelectric ceramic 1, an upper spring sheet 2 and a lower spring sheet 3 respectively arranged on opposite sides of the piezoelectric ceramic 1; the two ends of the upper spring sheet 2 are respectively fixed to the upper surface of the piezoelectric ceramic 1, and the upper spring sheet 2 is at least partially spaced from the piezoelectric ceramic 1; the two ends of the lower spring sheet 3 are respectively fixed to the lower surface of the piezoelectric ceramic 1, and the lower spring sheet 3 is at least partially spaced from the piezoelectric ceramic 1.

[0027] The piezoelectric transducer 100 further includes a plurality of resistance layers 4 respectively fixed to the upper spring plate 2 and the lower spring plate 3 . The plurality of resistance layers 4 are electrically connected to each other to form a bridge structure.

[0028] The piezoelectric transducer 100 further includes a plurality of resistance layers 4 respectively fixed to the first bending portion 22 , the second bending portion 23 , the third bending portion 32 , and the fourth bending portion 33 .

[0029] Specifically, the upper spring piece 2 includes a first base portion 25 located on the upper surface of the piezoelectric ceramic 1 and spaced apart from the piezoelectric ceramic 1, a first bent portion 23 and a second bent portion 24 extending obliquely from both ends of the first base portion 25 toward the ends of the piezoelectric ceramic 1, and a first fixing portion 21 and a second fixing portion 22 extending from the first bent portion 23 and the second bent portion 24 and fixed to the piezoelectric ceramic 1, respectively.

[0030] The lower spring piece 3 includes a second base portion 35 located on the lower surface of the piezoelectric ceramic 1 and spaced apart from the piezoelectric ceramic 1, a third bent portion 33 and a fourth bent portion 34 extending obliquely from two ends of the second base portion 35 toward two ends of the piezoelectric ceramic 1, and a third fixing portion 31 and a fourth fixing portion 32 extending from the third bent portion 33 and the fourth bent portion 34, respectively, and fixed to the piezoelectric ceramic 1.

[0031] The resistor layers 4 include four, and are respectively attached to the first bending portion 23 , the second bending portion 24 , the third bending portion 33 , and the fourth bending portion 34 . The four resistor layers 4 are connected via FPC.

[0032] The gaps formed between the upper spring piece 2, the lower spring piece 3 and the piezoelectric ceramic 1 are used to handle the deformation of the spring piece caused by external force. In a preferred embodiment, since the gaps between the upper spring piece 2, the lower spring piece 3 and the piezoelectric ceramic 1 are reduced when the upper spring piece 2, the lower spring piece 3 are deformed by external force, in order to avoid the multiple resistance layers 4 arranged on the first bending portion 22, the second bending portion 23, the third bending portion 24 and the fourth bending portion 25 from being damaged by the space squeeze contact between the spring piece and the piezoelectric ceramic, the multiple resistance layers 4 can be respectively adhered and fixed to the side of the first bending portion 23, the second bending portion 24, the third bending portion 33 and the fourth bending portion 34 away from the piezoelectric ceramic by means of adhesive bonding. Compared with the space of the gap, the size of the space between the external button structure and the piezoelectric transducer 100 is easier to control during manufacturing.

[0033] The resistor layer 4 is a piezoresistor, which can change its resistance value through deformation. When the upper spring piece 2 and the lower spring piece 3 are deformed by an external force, specifically the first bend 22, the second bend 23, the third bend 24, and the fourth bend 25 thereof, they are deformed. In the embodiment of the present invention, a resistor layer 4 made of a piezoresistive material is provided at the first bend 22, the second bend 23, the third bend 24, and the fourth bend 25. Therefore, when the resistor layer 4 is deformed at the first bend 22, the second bend 23, the third bend 24, and the fourth bend 25, the resistance value changes linearly with the magnitude of the deformation force. Correspondingly, by utilizing the resistance value of the resistor layer 4, a pressure-sensitive key using a piezoelectric transducer 100 can detect changes in key force, thereby achieving pressure detection. The variable pressure value detected by the key can be applied to functions such as key sliding recognition in smart devices such as mobile phones and watches, thereby enriching the functionality of pressure-sensitive keys.

[0034] Since resistors, as electrical components, are easily affected by the environment and produce resistance efficiency deviations, in order to reduce this influence, in an embodiment of the present invention, the multiple resistance layers 4 of the first bend 22, the second bend 23, the third bend 24 and the fourth bend 25 are electrically connected through FPC or other means to form a Wheatstone bridge structure. The Wheatstone bridge structure realizes a balanced bridge based on four resistors. During implementation, by connecting the Wheatstone bridge structure to the press detection circuit of the key structure, accurate detection of the resistance value can be achieved, thereby improving the accuracy of key pressure recognition.

[0035] The first fixing portion 21 and the second fixing portion 22 of the upper spring piece 2 are fixed to the piezoelectric ceramic 1 via an adhesive layer.

[0036] The third fixing portion 31 and the fourth fixing portion 32 of the lower elastic piece 3 are fixed to the piezoelectric ceramic 1 via an adhesive layer.

[0037] Compared with the related art, the piezoelectric transducer of the present invention includes a sheet-shaped piezoelectric ceramic, an upper spring sheet and a lower spring sheet respectively arranged on opposite sides of the piezoelectric ceramic; the two ends of the upper spring sheet are respectively fixed to the upper surface of the piezoelectric ceramic, and the upper spring sheet is at least partially spaced from the piezoelectric ceramic; the two ends of the lower spring sheet are respectively fixed to the lower surface of the piezoelectric ceramic, and the lower spring sheet is at least partially spaced from the piezoelectric ceramic; the piezoelectric transducer also includes a plurality of resistor layers respectively fixed to the upper spring sheet and the lower spring sheet, and the plurality of resistor layers are electrically connected to each other to form a bridge structure. In the above structure, the bent portion of the spring sheet will contract and deform when subjected to a pressing force, and the deformation will cause the resistor layer to deform. Since the resistance value of the resistor layer will change linearly under deformation, the external force applied to the pressure-sensing key can be identified by the resistance change, thereby realizing pressure change detection.

[0038] Example 2

[0039] An embodiment of the present invention further provides a pressure-sensitive key 200. Please refer to Figures 4 and 5. Figure 4 is a schematic diagram of the three-dimensional structure of the pressure-sensitive key provided by the embodiment of the present invention, and Figure 5 is an enlarged view of portion B in Figure 4. The pressure-sensitive key 200 includes a housing 201, a piezoelectric transducer 100 as described in any of the above embodiments housed within the housing 201, and a key bar 202 covering the housing 201 and the piezoelectric transducer. The upper spring 2 abuts against the key bar 202, and the lower spring 3 abuts against the housing 201. The pressure-sensitive key provided by the embodiment of the present invention can detect pressure changes by identifying external forces acting on the pressure-sensitive key through changes in resistance, using a structure in which a resistive layer is provided at the bent portion of the spring of the piezoelectric transducer 100. The variable pressure value detected by the key can be applied to functions such as key sliding recognition on smart devices such as mobile phones and watches, thereby enriching the functionality of the pressure-sensitive key.

[0040] The above description is only an embodiment of the present invention. It should be pointed out that those skilled in the art can make improvements without departing from the creative concept of the present invention, but these improvements all fall within the scope of protection of the present invention.

Claims

1. A piezoelectric transducer, comprising a sheet-shaped piezoelectric ceramic, an upper elastic sheet and a lower elastic sheet respectively disposed on opposite sides of the piezoelectric ceramic; both ends of the upper elastic sheet are respectively fixed to the upper surface of the piezoelectric ceramic, and at least part of the upper elastic sheet is spaced from the piezoelectric ceramic; both ends of the lower elastic sheet are respectively fixed to the lower surface of the piezoelectric ceramic, and at least part of the lower elastic sheet is spaced from the piezoelectric ceramic; Characterized in that, the piezoelectric transducer further comprises a plurality of resistance layers respectively fixed to the upper elastic sheet and the lower elastic sheet, and the plurality of resistance layers are electrically connected to each other to form a bridge structure.

2. The piezoelectric transducer according to claim 1, Characterized in that, the upper elastic sheet includes a first base portion located on the upper surface of the piezoelectric ceramic and spaced from the piezoelectric ceramic, a first bending portion and a second bending portion respectively extending obliquely from both ends of the first base portion toward both ends close to the piezoelectric ceramic, and a first fixing portion and a second fixing portion respectively extending from the first bending portion and the second bending portion and fixed to the piezoelectric ceramic; the lower elastic sheet includes a second base portion located on the lower surface of the piezoelectric ceramic and spaced from the piezoelectric ceramic, a third bending portion and a fourth bending portion respectively extending obliquely from both ends of the second base portion toward both ends close to the piezoelectric ceramic, and a third fixing portion and a fourth fixing portion respectively extending from the third bending portion and the fourth bending portion and fixed to the piezoelectric ceramic; there are four resistance layers, and they are respectively attached and fixed to the first bending portion, the second bending portion, the third bending portion and the fourth bending portion, and the four resistance layers are connected by an FPC.

3. The piezoelectric transducer according to claim 2, Characterized in that, a Wheatstone bridge structure is formed by connecting between the four resistance layers.

4. The piezoelectric transducer according to claim 1, Characterized in that, the resistance layer is a varistor.

5. The piezoelectric transducer according to claim 2, Characterized in that, the plurality of resistance layers are respectively disposed on the sides of the first bending portion, the second bending portion, the third bending portion and the fourth bending portion away from the piezoelectric ceramic.

6. The piezoelectric transducer according to claim 2, Characterized in that, both the first fixing portion and the second fixing portion are fixed to the piezoelectric ceramic through an adhesive layer.

7. The piezoelectric transducer according to claim 2, Characterized in that, both the third fixing portion and the fourth fixing portion are fixed to the piezoelectric ceramic through an adhesive layer.

8. A pressure sensing button, Characterized in that, comprising a housing, a piezoelectric transducer as described in any one of claims 1 to 7 received in the housing, and a button strip covering the piezoelectric transducer and covering the piezoelectric transducer, the upper elastic sheet abuts against the button strip, and the lower elastic sheet abuts against the housing.

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