Patent Publication Number: US-2022214790-A1

Title: Touchpad and electronic device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of PCT Application No. PCT/CN2021/076103, filed Feb. 8, 2021 which claims priorities to PCT Application No. PCT/CN2021/070375, filed Jan. 5, 2021, and each of which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present disclosure relate to the field of electronic technology, and in particular to a touchpad and an electronic device. 
     BACKGROUND 
     Touchpad is an input device applied to an electronic device for controlling a screen cursor. The touchpad detects a small capacitance change when operations are applied by a user&#39;s finger in a panel area, and obtains touch information such as high-resolution finger coordinates, so as to accurately control the screen cursor to move and/or click. Conventionally, the touchpad has its back equipped with a single button, behavior of which is detected to achieve functions as left and right clicks of a typical mouse. 
     In order to improve convenience for operation of the touchpad, a pressure-detection based touchpad gradually becomes a new trend, which eliminates physical buttons of the conventional touchpad and has functions such as pressure sensing and vibration feedback. 
     At present, pressure-detection based touchpad of piezoelectric ceramic type has defects such as low vibration, poor user experience, low accuracy of pressure detection and failure to detect continuous pressure. 
     SUMMARY 
     In view of the above, the present disclosure provides a touchpad and an electronic device, which improve pressure detection accuracy of the touchpad, are capable of detecting a continuous pressure, have a good vibration feedback effect, and thus improve user experience. 
     Embodiments of the present disclosure provide a touchpad, including a touch panel, a plurality of pressure sensors and a piezoelectric ceramic assembly. The plurality of pressure sensors are fixed to an elastic bracket and configured to detect a pressure applied on the touch panel. The piezoelectric ceramic assembly includes a piezoelectric ceramic plate configured to provide a vibration feedback to a user, and the piezoelectric ceramic assembly is fixed below the touch panel in a suspended manner and spaced from the elastic bracket. 
     The piezoelectric ceramic plate is employed to provide the vibration feedback, meanwhile the pressure sensor is employed to detect the pressure, thereby improving accuracy of pressure detection, and making it possible to detect a continuous pressure. In addition, the piezoelectric ceramic assembly is fixed below the touch panel in a suspended manner and thus spaced from the elastic bracket for supporting the pressure sensor, so that the vibration of the piezoelectric ceramic plate shall not affect the pressure detection of the pressure sensor, the vibration of the piezoelectric ceramic plate is strongly felt, and thus a good user experience is offered. In addition, a piezoelectric ceramic plate serves as a vibration source, such that the touchpad has a lighter and thinner structure and generates a vibration to be clearly and sufficiently felt. 
     In an embodiment, the touchpad further includes a fixing structure for suspending and fixing the piezoelectric ceramic assembly below the touch panel. 
     The piezoelectric ceramic plate is fixed below the touch panel in a suspended manner with a fixing structure, which is low cost and easy to install. 
     In an embodiment, the piezoelectric ceramic plate includes a piezoelectric ceramic sheet, a metal substrate and an electrode; and both ends of the metal substrate protrude from the piezoelectric ceramic and the electrode, and fixed below the touch panel by the fixing structure. 
     Both ends of the metal substrate protrude from the piezoelectric ceramic and the electrodes and fixed below the touch panel by the fixing structure, which enables the piezoelectric ceramic assembly to be fixed below the touch panel in a suspended manner. 
     In an embodiment, the piezoelectric ceramic assembly further includes a weighting block fixed to a bottom of the piezoelectric ceramic plate and configured to strengthen a vibration of the piezoelectric ceramic plate. 
     The weighting block may increase the counter acting force between the piezoelectric ceramic plate and the circuit board or reinforcing plate below the touch panel, thereby strengthening the vibration of the piezoelectric ceramic plate and reducing the vibration sound. 
     In an embodiment, the weighting block is a cuboid block defining a first groove in which the piezoelectric ceramic plate is disposed. 
     A thickness of the touch panel can be further reduced by disposing the piezoelectric ceramic plate in the groove defined by the weighting block. 
     In an embodiment, the weighting block is fixed at or near a center of gravity of the piezoelectric ceramic plate. 
     Since the weighting block is fixed at the center of gravity of the piezoelectric ceramic plate, the piezoelectric ceramic plate is subjected to a force evenly distributed. On the one hand, the pressure applied on one end of the piezoelectric ceramic plate is not larger than that on the other end, which prevents the fixing structure from easily falling off, and on the other hand, the vibration feedback effect is better. 
     In an embodiment, the weighting block is a copper block, a lead block or a steel block. 
     The weighting block with a large density is selected, which has a small volume and a good weighting effect. 
     In an embodiment, a weight of the weighting block is a range from 2.4 g to 2.6 g. 
     The weighting block of an appropriate weight is selected to enhance the vibration feedback effect. 
     In an embodiment, a distance between the fixing structure and the piezoelectric ceramic sheet is greater than or equal to 0.1 mm. 
     A gap space the fixing structure from the piezoelectric ceramic sheet, so that the fixing structure does not affect the vibration of the piezoelectric ceramic plate. 
     In an embodiment, the piezoelectric ceramic plate includes a piezoelectric ceramic sheet, a metal substrate and an electrode. One end of the piezoelectric ceramic sheet is fixed below the touch panel by the fixing structure. 
     In an embodiment, one end of the metal substrate protrudes from the piezoelectric ceramic and the electrode, and one end of the metal substrate and the end of the piezoelectric ceramic are both fixed below the touch panel by the fixing structure. 
     The end of the metal substrate protrudes from the piezoelectric ceramic and the electrode and is fixed below the touch panel by the fixing structure, which enables the piezoelectric ceramic assembly to be fixed under the touch panel in a suspended manner. 
     In an embodiment, the fixing structure includes a glue, a double-sided adhesive tape, a screw, a buckle or a solder. 
     Optionally, the piezoelectric ceramic assembly may be fixed to the lower surface of the circuit board by gluing, adhering, welding, screwing, snapping, or the like. The welding may be soldering or laser spot welding. 
     In an embodiment, a thickness of the fixing structure is in a range from 0.4 mm to 0.6 mm. 
     The fixing structure has an appropriate thickness, which, on the one hand, is thick enough to keep the piezoelectric ceramic plate out of contact with the touch panel during vibrating, and on the other hand, is thin enough to not increase the thickness of the touch panel. 
     In an embodiment, a length of the piezoelectric ceramic plate in in a range from 49 mm to 51 mm, and a width of the piezoelectric ceramic plate in in a range from 5 mm to 7 mm. 
     In an embodiment, the touchpad includes one piezoelectric ceramic plate arranged at a center of the touch panel and mounted in a direction parallel to a long side or a short side of the touch panel. 
     In an embodiment, the touchpad includes a plurality of piezoelectric ceramic plates. The plurality of piezoelectric ceramic plates disposed parallelly side by side. Alternatively, some of the plurality of piezoelectric ceramic plates are arranged side by side parallel to a long side of the touch panel, and other some of the plurality of piezoelectric ceramic plates are arranged side by side parallel to a short side of the touch panel. 
     The plurality of piezoelectric ceramic plates are provided to strengthen the vibration. The piezoelectric ceramic plates may be parallel or inclined to any side of the touch panel, resulting in a flexible installation. By evenly and symmetrically distributing the plurality of piezoelectric ceramic plates on the touch panel, thereby increasing consistency of vibration strength at different positions of the touch panel. 
     In an embodiment, the touch pad includes four pressure sensors. Projections of the four pressure sensors on the touch panel are located at four corners of the touch panel, respectively. Alternatively, projections of the four pressure sensors on the touch panel are located at centers of four sides in the touch panel, respectively. 
     In an embodiment, the plurality of pressure sensors are fixed beside the touch panel, and projections of the plurality of pressure sensors on a plane where the touch panel is located is outside a region of the touch panel. 
     The pressure sensors are fixed beside of the touchpad, so that the thickness of the touch panel can be reduced. 
     In an embodiment, the elastic bracket includes two short shafts fixed to an edge region below the touch panel and one long shaft, and the plurality of pressure sensors are disposed on the short shafts. 
     In an embodiment, the long shaft extends along a side of the touch panel such that the plurality of pressure sensors are located on the plane where the touch panel is located. 
     In an embodiment, the touchpad includes two elastic brackets disposed opposite to each other, each of which is provided with two pressure sensors. 
     In an embodiment, the elastic bracket defines a second groove, a top portion of each of two side walls of the second groove is fixed below the touch panel, and the plurality of pressure sensors are fixed to a bottom wall of the second groove. 
     In an embodiment, the top portion of each of the two side walls extends outward to form a step, and an upper surface of the step is fixed below the touch panel. 
     The elastic bracket adopts a groove structure, is connected to the touch panel with the surface of the outwardly extending step, thereby strengthening stability of the structure. 
     In an embodiment, a stacked structure below the touch panel defines a third groove in which top portions of the two side walls of the second groove are fixed. 
     By fixing the elastic bracket in the groove defined by the stacked structure below the touch panel, it is advantageous to reduce a thickness of the touch panel. 
     In an embodiment, the touch pad further includes a reinforcing plate fixed to both ends of a lower surface of a circuit board and configured to increase rigidity of the touch panel. 
     The reinforcing plate serves to increase the rigidity of the touch panel, thereby reducing the deformation and collapse of the touch panel caused when being pressed by the user. 
     Embodiments of the present disclosure provide an electronic device including a touchpad in any one of the embodiments of the first aspect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic exploded view of a typical pressure-detection based touchpad. 
         FIG. 2  is a schematic block diagram of a touchpad according to the embodiment of the present disclosure. 
         FIG. 3  is a schematic diagram of an example of a stacked structure of the touchpad according to the embodiment of the present disclosure. 
         FIG. 4  is a schematic diagram of another example of the stacked structure of the touchpad according to the embodiment of the present disclosure. 
         FIGS. 5 to 8  are schematic diagrams illustrating examples of pressure sensors distribution in the touchpad according to the embodiment of the present disclosure. 
         FIG. 9  is a schematic diagram of an example of vibration feedback of the piezoelectric ceramic plate according to the embodiment of the present disclosure. 
         FIG. 10  is a schematic structural diagram of an example of the piezoelectric ceramic plate according to the embodiment of the present disclosure. 
         FIG. 11  is a schematic diagram of an example of installation of the piezoelectric ceramic plate according to the embodiment of the present disclosure. 
         FIG. 12  is a schematic diagram of a further example of the stacked structure of the touchpad according to the embodiment of the present disclosure. 
         FIG. 13  is a schematic diagram of another example of installation of the piezoelectric ceramic plate according to the embodiment of the present disclosure. 
         FIG. 14  is a schematic diagram of a further example of installation of the piezoelectric ceramic plate according to the embodiment of the present disclosure. 
         FIGS. 15 to 17  are schematic structural diagrams of other examples of the piezoelectric ceramic plate according to the embodiment of the present disclosure. 
         FIGS. 18 to 19  are schematic diagrams of examples of installation direction of the piezoelectric ceramic plate according to the embodiment of the present disclosure. 
         FIGS. 20 to 23  are schematic diagrams of examples of distribution of the piezoelectric ceramic plates according to the embodiment of the present disclosure. 
         FIGS. 24 and 25  are bottom views of examples of the touchpad according to the embodiment of the present disclosure. 
         FIG. 26  is a schematic exploded view of an example of the touchpad according to the embodiment of the present disclosure. 
         FIG. 27  is a schematic diagram of an example of interaction of internal structure of the touchpad according to the embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Technical solutions according to the embodiments of the present disclosure will be described below with reference to the accompanying drawings. 
     Touchpad is an input device applied to an electronic device for controlling a screen cursor. The touchpad detects a small capacitance change when operations are applied by a user&#39;s finger in a panel area, and obtains touch information such as high-resolution finger coordinates, so as to accurately control the screen cursor to move and/or click. Conventionally, the touchpad has its back equipped with a single button, behavior of which is detected to achieve functions as left and right clicks of a typical mouse. 
     In order to improve convenience for operation of the touchpad, a pressure-detection based touchpad gradually becomes a new trend, which eliminates physical buttons used in the conventional touchpad and has functions such as pressure sensing and vibration feedback. 
     A typical pressure-detection based touchpad employs a detection-control scheme with a linear motor, which mainly has defects as follows. 
     1. The resulting structure has a large thickness and thus occupies an internal space for a battery of an electronic device, which causes the touchpad inadaptable to a thin and light electronic device. 
     2. The vibration of the linear motor is delayed and unclearly to be felt. 
     3. The power consumption of the linear motor is high. 
     Another typical pressure-detection based touchpad employs a detection-control scheme with piezoelectric ceramic, which becomes more and more popular because of its advantages of thinness and lightness. Embodiments of the present disclosure are implemented based on the detection-control scheme with piezoelectric ceramic. 
     A typical pressure-detection based touchpad based on a detection-control scheme with piezoelectric ceramic will be described below with reference to  FIG. 1 . 
       FIG. 1  is a schematic exploded view of a typical pressure-detection based touchpad. As shown in  FIG. 1 , it includes, from top to bottom, a touch panel, a foam, a piezoelectric ceramic plate, a flexible printed circuit (FPC), a foam, an insulating polyethylene terephthalate (PET) gasket, a sheet metal holder and an upper cover. The touch panel may include a cover plate and a touch printed circuit board (PCB). Since the piezoelectric ceramic plate can also perform pressure detection, the foam may also be referred to as a sensor foam. 
     Specifically, when a user presses the touch panel with a finger, the foam below the touch panel transmits a pressure to the piezoelectric ceramic plate. The piezoelectric ceramic plate generates an electrical signal under a direct piezoelectric effect. The control chip generates a driving signal after receiving the electrical signal, and drives the piezoelectric ceramic plate to generate vibration which is then transmitted to the touch panel through the foam. The foams above and below the piezoelectric ceramic plate are mainly serves as a cushion against the pressure and meanwhile absorbs a sound caused by the vibration. The FPC is used to connect a plurality of piezoelectric ceramic plates and transmit the electrical signal to the control chip. The sheet metal holder and the cover serve as support. 
     Since the piezoelectric ceramic plate generate the electric signal for pressure detection by an electric potential difference generated through expansion and contraction between foams, accuracy of the pressure detection is low, and it is impossible to detect a continuous pressure. In addition, the vibration of a single piezoelectric ceramic plate is weakly felt, resulting in poor user experience. In other to make the vibration to be strongly felt, a plurality of piezoelectric ceramic plates are required and should be driven separately, resulting in high cost. 
     In view of the above, the embodiments of the present disclosure provide a touchpad based on the detection-control scheme with piezoelectric ceramic, which can solve the above various problems. 
     It should be appreciated that the technical solutions according to the embodiment of the present disclosure may be applied to various electronic devices. 
     For example, the electronic devices may be portable or mobile computing devices such as smartphones, laptops, tablets, gaming devices or the like, and other electronic devices such as electronic databases, automobiles, bank automated teller machines (ATM) or the like. The embodiment of the present disclosure is not limited thereto. 
       FIG. 2  is a schematic structural diagram of a touchpad  100  according to the embodiment of the present disclosure. As shown in  FIG. 2 , the touchpad  100  includes:
         a touch panel  101 ;   a pressure sensor  102  configured to convert a deformation of the pressure sensor into a first electrical signal for pressure detection when the touch panel is under pressure;   an elastic bracket  103  configured to support the pressure sensor, and drive the pressure sensor to elastically deform therewith when the touch panel is under pressure;   a piezoelectric ceramic assembly including a piezoelectric ceramic plate  104  configured to provide a vibration feedback to a user when the first electrical signal is greater than a first threshold, where the piezoelectric ceramic assembly is fixed below the touch panel in a suspended manner and spaced from the elastic bracket.       

     Specifically, in this embodiment, when being subjected to a pressure, the touch panel transmits the pressure to the elastic bracket below, the bracket is bent to drive the pressure sensor supported by the bracket to elastically deform therewith, and then the pressure sensor converts a detected deformation into an electrical signal for pressure detection. When it is detected that the electrical signal converted by the pressure sensor is greater than a first threshold value, the piezoelectric ceramic plate feeds back a vibration to the user by driving the touch panel to vibrate therewith. The vibration feedback may enable the user to judge whether his press operation is effective, thereby minimizing repetitive gestures. 
     In the embodiment of the present disclosure, the piezoelectric ceramic assembly is spaced from the elastic bracket, which means that the piezoelectric ceramic assembly is kept out of contact with the elastic bracket during a process from non-deformation to deformation of the elastic bracket. The piezoelectric ceramic assembly is fixed below the touch panel in a suspended manner, which means that the piezoelectric ceramic assembly has no support at its bottom, and there is a gap between the piezoelectric ceramic assembly and the touch panel. 
     It should be noted that the first threshold is a specified threshold, which may be obtained empirically. The first threshold may be a critical value for a pressure degree at which the user can feel the vibration. The first threshold is greater than 0. 
     As an example, critical values for various pressure degrees may be stored in the electronic device, and the user may select one of them according to his habits. For example, the electronic device stores a critical value for a light pressing, a critical value for a medium pressing, and a critical value for a heavy pressing, and the user may select one of them according to the pressure degree he gets used to. 
     Therefore, the touchpad of the embodiment of the present disclosure adopts a piezoelectric ceramic plate as a vibration source, and thus has a lighter and thinner structure and generates a vibration to be clearly and sufficiently felt. In addition, the piezoelectric ceramic plate is employed to provide the vibration feedback, meanwhile the pressure sensor is employed to detect the pressure, thereby improving accuracy of pressure detection, and making it possible to detect a continuous pressure. In addition, the piezoelectric ceramic assembly is fixed below the touch panel in a suspended manner and thus spaced from the elastic bracket for supporting the pressure sensor, so that the vibration of the piezoelectric ceramic plate shall not affect the pressure detection of the pressure sensor, the vibration of the piezoelectric ceramic plate is strongly felt, and thus a good user experience is offered. Therefore, a same vibration feeling is offered to the user with less piezoelectric ceramic plates and thus less cost. 
       FIG. 3  is a schematic diagram of an example of a stacked structure of the touchpad  100  according to the embodiment of the present disclosure. 
     As shown in  FIG. 3 , in an example of the embodiment of the present disclosure, the touchpad  100  includes:
         a circuit board  105  fixed to a lower surface of the touch panel, and configured to process the first electrical signal and control the piezoelectric ceramic plate to provide the vibration feedback to the user when the first electrical signal is greater than the first threshold.       

     As shown in  FIG. 3 , the circuit board  105  may be bonded to the lower surface of the touch panel  101 . For example, the circuit board  105  is fixed to the lower surface of the touch panel  101  by an adhesive  131 . The circuit board  105  may be equipped with electronic components and circuits, and configured to process electrical signals generated based on pressure, vibration, etc., and implement a system setting function. 
     As an example, the circuit board  105  may include a pressure detection chip, a piezoelectric ceramic drive chip, a peripheral circuit, a connector, etc. 
     Specifically, the pressure detection chip may judge whether the first electrical signal detected by the pressure sensor reaches the first threshold value, and send a vibration instruction to the piezoelectric ceramic drive chip if the first threshold value is reached. After receiving the vibration instruction, the piezoelectric ceramic drive chip drives the piezoelectric ceramic plate to vibrate according to a pre-set mode, and the piezoelectric ceramic plate drives the touch panel to vibrate therewith to feed back the vibration to the user. 
     As an example of the embodiment of the present disclosure, the touchpad  100  further includes:
         a capacitance detection array configured to convert a capacitance change caused by finger touch into a second electrical signal for touch detection.       

     As an example, the circuit board  105  may also be configured to process the second electrical signal. 
     That is, the circuit board  105  may further include a touch detection chip. The touch detection chip and the pressure detection chip may be collectively referred to as a control chip. 
     As an example, a surface of the circuit board  105  may have a capacitance detection array formed by copper sheets. When the touch panel is touched by a finger, the capacitance detection array converts a capacitance change into an electrical signal and transmits the electrical signal to the touch detection chip. 
     In the embodiment of the present disclosure, the touch detection chip and the pressure detection chip are combined into one, that is, a single chip is employed to perform both pressure detection and touch detection, which reduces power consumption, simplifies circuit structure, saves cost for the system, and provides a faster system response. 
       FIG. 4  is a schematic diagram of another example of the stacked structure of the touchpad  100  according to the embodiment of the present disclosure. Compared with  FIG. 3 , the touchpad  100  in  FIG. 4  further includes:
         a reinforcing plate  108  fixed to both ends of a lower surface of the circuit board  105 , and configured to increase rigidity of the touch panel  101 .       

     Specifically, the reinforcing plate  108  and the circuit board  105  may be bonded by an adhesive  134 , and the elastic bracket  103  is bonded to a lower surface of the reinforcing plate  108  by an adhesive  132 . 
     As an example, the reinforcing plate may be an aluminum plate or a steel plate. 
     The reinforcing plate is configured to increase the rigidity of the touch panel  101 , thereby reducing the deformation and collapse of the touch panel caused when being pressed by the user. 
     As shown in  FIGS. 3 and 4 , the elastic bracket  103  is fixed below the touch panel  101 . 
     Specifically, as shown in  FIG. 3 , the elastic bracket  103  is fixed to the lower surface of the circuit board  105 . As shown in  FIG. 4 , the elastic bracket  103  is fixed to the lower surface of the reinforcing plate  108 . 
     As an example, the elastic bracket  103  defines a second groove. A top portion of each of two side walls of the second groove is fixed below the touch panel  101 , and the pressure sensor  102  is fixed to a bottom wall of the second groove. 
     In an example, the top portion of each side wall extends outward to form a step. An upper surface of the step is fixed below the touch panel  101 . The pressure sensor  102  is fixed to the bottom wall of the second groove. For example, the upper surface of the step is fixed to the lower surface of the circuit board  105 , or the upper surface of the step is fixed to the lower surface of the reinforcing plate  108 . 
     Specifically, the upper surface of the step may be fixedly connected to the lower surface of the circuit board  105  or the reinforcing plate  108  by the adhesive  132 . The pressure sensor  102  may be fixedly connected to the bottom wall of the second groove of the elastic bracket by the adhesive  133 . 
     In another example, the stacked structure below the touch panel  101  defines a third groove in which the top portions of the two side walls of the second groove are fixed. For example, the lower surface of the reinforcing plate  108  defines a third groove in which the top portions of the two side walls are fixed. 
     By fixing the elastic bracket in the groove defined by the stacked structure below the touch panel, it is advantageous to reduce a thickness of the touch panel. 
     In another example, the two side walls of the elastic bracket may also be beveled. 
     It should be appreciated that the specific shape of the elastic bracket is not limited in this embodiment of the present disclosure, as long as the pressure sensor can be supported and deformed together with the elastic bracket when the touch panel is under pressure. 
     As an example of the embodiment of the present disclosure, one or more elastic brackets  103  may be provided. One or more pressure sensor  102  may be disposed at the bottom wall of one elastic bracket  103 . When a plurality of elastic brackets  103  are provided, the plurality of elastic brackets  103  may be independent form each other, or may be connected as a whole and fixed to edge regions of four sides of the circuit board  105 . 
     The pressure sensor  102  is fitly attached to the elastic bracket  103 . When the elastic bracket  103  is bent and deformed, the pressure sensor  102  is deformed together with the elastic bracket  103 . 
     As an example, the touchpad  100  includes a plurality of pressure sensors  102 , projections of the plurality of pressure sensors  102  on the touch panel  101  may be located at a position of at least one corner of the touch panel  101  and/or a center of at least one side of the touch panel  101 . 
     With the plurality of pressure sensors, the pressure can be dispersed thereon, thereby increasing structural stability of the touchpad. 
     In an example, as shown in  FIG. 5 , the plurality of pressure sensors are four pressure sensors  102 , and projections of the four pressure sensors  102  on the touch panel  101  are located at four corners of the touch panel  101 , respectively. 
     In another example, as shown in  FIG. 6 , the plurality of pressure sensors are four pressure sensors  102 , and projections of the four pressure sensors  102  on the touch panel  101  are located at centers of four sides of the touch panel  101 , respectively. 
     In a further example, as shown in  FIG. 7 , the plurality of pressure sensors are six pressure sensors  102 , and projections of the six pressure sensors  102  on the touch panel  101  are located at four corners of the touch panel  101  and at centers of two long sides of the touch panel  101 , respectively. 
     In another further embodiments, as shown in  FIG. 8 , the plurality of pressure sensors are eight pressure sensors  102 , and projections of the eight pressure sensors  102  on the touch panel  101  are located at four corners of the touch panel  101  and at centers of four sides of the touch panel  101 , respectively. 
     The uniformity of pressure detection can be improved by distributing the plurality of pressure sensors at the four corners and/or the centers of the four sides of the touch panel. 
     As an example, the touch panel  101  may be used for being touched and pressed by the user, and may further server as decoration. The touch panel  101  may be made from glass or Mylar. 
     As an example, the pressure sensor  102  may be a pressure sensor of piezoresistive type. 
     As an example, the elastic bracket  103  may be a steel sheet or an aluminum sheet. 
     As further shown in  FIGS. 3 and 4 , the touchpad  100  further includes:
         a fixing structure  106  by which the piezoelectric ceramic assembly below the touch panel  101  is suspended.       

     Specifically, the piezoelectric ceramic assembly is fixed to the lower surface of the circuit board  105  by the fixing structure  106 . For example, the fixing structure  106  may be a glue, a double-sided adhesive tape, a solder, a screw or a buckle. That is, the piezoelectric ceramic assembly may be fixed to the lower surface of the circuit board  105  by gluing, adhering, welding, screwing, snapping, or the like. The welding may be soldering or laser spot welding. 
     As an example, as shown in  FIG. 4 , the reinforcing plate  108  needs to spare an accommodating space for the piezoelectric ceramic assembly. That is, the reinforcing plate  108  is provided with a window at a mounting position of the piezoelectric ceramic assembly. 
     As further shown in  FIGS. 3 and 4 , in an example of the present disclosure, the piezoelectric ceramic assembly further includes:
         a weighting block  107  fixed to a bottom of the piezoelectric ceramic plate  104 , and configured to strengthen the vibration of the piezoelectric ceramic plate  104 .       

     Specifically, as shown in  FIG. 9 , the piezoelectric ceramic drive chip on the circuit board  105  generates an alternating voltage. Under an inverse piezoelectric effect, a metal substrate of the piezoelectric ceramic plate  104  is bent into an arcuate shape, a force in a direction opposite to the bending direction is generated at both ends and is equal to a reacting force caused by the deformation. The weighting block with an appropriate weight increases the counter acting forces between the metal substrate and the circuit board  105 , thereby strengthening the vibration of the touch panel  101 . Alternatively, the weighting block  107  may not be required according to actual requirements. 
     As an example, the weighting block  107  may be mounted at or near a center of gravity of the piezoelectric ceramic plate  104 , may be fixed by a glue or a double-sided adhesive tape. The weighting block  107  may be a copper block, a lead block, a steel block, or the like having a relatively large density. 
     In the embodiment of the present disclosure, since the weighting block is fixed at the center of gravity of the piezoelectric ceramic plate, the piezoelectric ceramic plate is subjected to a force evenly distributed. On the one hand, the pressure applied on one end of the piezoelectric ceramic plate is not larger than that on the other end, which prevents the fixing structure from easily falling off, and on the other hand, the vibration feedback effect is better. 
     In addition, the weighting block with a large density is selected, which has a small volume and a good weighting effect. 
     In an example, the weighting block  107  may be a cuboid block defining a first groove in which the piezoelectric ceramic plate  104  is disposed. 
     A thickness of the touch panel can be further reduced by disposing the piezoelectric ceramic plate in the groove of the weighting block. 
     As an example, the weighting block  107  may also be of other shapes, for example, the weighting block  107  may be shaped in accordance with the shape of the piezoelectric ceramic plate  104 . The first groove may be of other shapes, such as trapezoid, which is not limited in this embodiment of the present disclosure. 
     As an example of the embodiment of the present disclosure, a weighting block of an appropriate weight is selected to enhance the vibration feedback effect. For example, a length and a width of the piezoelectric ceramic plate  104  may be 50 mm and 6 mm, respectively, and a weight of the weighting block  107  may be 2.5 g. 
     Each of the length and the width of the piezoelectric ceramic plate  104  has a deviation, for example, of ±1 mm. That is, the length of the piezoelectric ceramic plate may be in a range from 49 mm to 51 mm, and the width of the piezoelectric ceramic plate may be in a range from 5 mm to 7 mm. 
     The weight of the weighting block  107  has a deviation, for example, of ±0.1 g. That is, the weight of the weighting block may be in a range from 2.4 g to 2.6 g. 
     The embodiment of the present disclosure will be described with an example in which the wight of the weight block  107  is about 2.5 g. 
     As shown in  FIG. 10 , the piezoelectric ceramic plate generally includes a piezoelectric ceramic sheet, a metal substrate, and an electrode. Specifically, a electrode, a piezoelectric ceramic sheet, a metal substrate, a piezoelectric ceramic sheet, and a electrode are sequentially stacked from top to bottom. The electrodes and the piezoelectric ceramic sheets are flush with each at both ends, and both ends of the metal substrate protrudes out of the piezoelectric ceramic sheets. 
     As an example, both protruding ends of the metal substrate of the piezoelectric ceramic plate  104  may be fixed to the lower surface of the circuit board  105  by the fixing structure  106 , so that the piezoelectric ceramic plate  104  is suspended below the touch panel  101 . The installation may be as shown in  FIG. 11 . 
     As another example, a groove may be defined at a middle of an upper surface of the piezoelectric ceramic plate  104  to expose the metal substrate. The fixing structure  106  is disposed in the groove and fixed to the lower surface of the circuit board  105  so that the piezoelectric ceramic plate  104  is suspended below the touch panel  101 . 
     As an example, a thickness of the fixing structure  106  may be about 0.5 mm. A gap between the fixing structure  106  and the piezoelectric ceramic sheet is at least greater than or equal to 0.1 mm, for example, in a range from 0.1 mm to 0.2 mm. The gap space the fixing structure from the piezoelectric ceramic sheet, so that the fixing structure does not affect the vibration of the piezoelectric ceramic plate. In addition, the fixing structure has an appropriate thickness, which, on the one hand, is thick enough to keep the piezoelectric ceramic plate out of contact with the touch panel during vibrating, and on the other hand, is thin enough to not increase the thickness of the touch panel. 
     The embodiment of the present disclosure further provides a single-end fixation scheme without a weighting block. 
       FIG. 12  is a schematic diagram of a further example of the stacked structure of the touchpad according to the embodiment of the present disclosure. The structure is the same as that shown in  FIG. 3 , except that the touch panel  100  does not include a weighting block. 
     Specifically, one end of the metal substrate protrudes from the piezoelectric ceramic sheet and the electrode. The protruding end of the metal substrate of the piezoelectric ceramic plate  104  and the piezoelectric ceramic sheet may be fixed to the lower surface of the circuit board  105  by a fixing structure  106  so that the piezoelectric ceramic plate  104  is suspended below the touch panel  101 . The fixing structure  106  is disposed as close as possible to a trailing end of the metal substrate. A length of the fixing structure  106  is not more than half a total length of the piezoelectric ceramic plate  104 , and a thickness of the fixing structure is in a range from 0.4 mm to 0.6 mm. The installation may be as shown in  FIG. 13 . Since the piezoelectric ceramic assembly is fixed in a suspended manner below the touch panel at a single end of the piezoelectric ceramic assembly, according to the lever principle, when the piezoelectric ceramic assembly receives the vibration instruction, one end of the piezoelectric ceramic assembly vibrates up and down according to the driving signal output by the piezoelectric ceramic drive chip. Since the rigidity of the piezoelectric ceramic sheet is greater than the rigidity of the metal substrate, the vibration of the end of the piezoelectric ceramic assembly is transmitted to an other end of the piezoelectric ceramic assembly, so that the touch panel is driven to vibrate, the vibration of the piezoelectric ceramic plate is stronger and the user experience is better. Therefore, a same vibration feeling is offered to the user with less piezoelectric ceramic plates and thus less cost. Since both the protruding end of the metal substrate and the piezoelectric ceramic sheet are fixed to the lower surface of the circuit board  105  by a fixing structure  106 , a service life of the piezoelectric ceramic assembly is longer, and the piezoelectric ceramic sheet is prevented from being separated from the metal substrate due to long-time vibration. 
     As another example, the metal substrate may not protrude from the piezoelectric ceramic sheet and the electrode. The piezoelectric ceramic sheet of the piezoelectric ceramic plate  104  may be fixed to the lower surface of the circuit board  105  by a fixing structure  106  so that the piezoelectric ceramic plate  104  is suspended below the touch panel  101 . The fixing structure  106  is disposed as close as possible to a trailing end of the piezoelectric ceramic sheet. The length of the fixing structure  106  is not more than half a total length of the piezoelectric ceramic plate  104 , and the thickness of the fixing structure is in a range from 0.4 mm to 0.6 mm. The installation may be as shown in  FIG. 14 . In  FIG. 11 , both protruding ends of the metal substrate are fixed to the lower surface of the circuit board  105  by the fixing structure  106 , the driving signal output from the piezoelectric ceramic drive chip is applied to the electrodes at both ends, so that the bending deformation of the metal substrate cause a vibration up and down, thereby driving the touch panel to vibrate. In the embodiment of the present disclosure, according to the lever principle, since the rigidity of the piezoelectric ceramic sheet is greater than the rigidity of the metal substrate, the vibration of one end of the piezoelectric ceramic assembly is transmitted to the other end of the piezoelectric ceramic assembly, thereby driving the touch panel to vibrate. 
     As an example, the piezoelectric ceramic plate  104  may also be fixed to the lower surface of the circuit board  105  by two fixing structures  106  disposed as close as possible. One of the two fixing structures is disposed as close as possible to a trailing end of the piezoelectric ceramic plate  104 . The piezoelectric ceramic assembly is fixed in a suspended manner at one end below the touch panel by two fixing structures, and the touch panel is driven to vibrate according to the lever principle, which increases the structural reliability and the vibration strength of the touchpad. 
     As an example, the piezoelectric ceramic plate may be a single-sided single-layer plate as shown in  FIG. 15 , which, for example, may include an electrode, a piezoelectric ceramic sheet and a metal substrate stacked sequentially stacked sequentially. Alternatively, the piezoelectric ceramic plate may be a single-layer double-sided plate as shown in  FIG. 10 , which, for example, may include an electrode, a piezoelectric ceramic sheet, a metal substrate, a piezoelectric ceramic sheet and a further electrode stacked sequentially from top to bottom. Alternatively, the piezoelectric ceramic plate may be a multi-layer single-sided plate as shown in  FIG. 16 , which, for example, may include an electrode, a piezoelectric ceramic sheet, an electrode, a piezoelectric ceramic sheet, an electrode, a piezoelectric ceramic sheet and a metal substrate stacked sequentially from top to bottom. Alternatively, the piezoelectric ceramic plate may be a strip-shaped multi-layer multi-sided plate as shown in  FIG. 17 , which, for example, may include an electrode, a piezoelectric ceramic sheet, an electrode, a piezoelectric ceramic sheet, an electrode, an electrode, a piezoelectric ceramic sheet, a metal substrate, a piezoelectric ceramic sheet, an electrode, a piezoelectric ceramic sheet, an electrode, a piezoelectric ceramic sheet and an electrode stacked sequentially from top to bottom. Preferably, the single-layer double-sided piezoelectric ceramic plate may achieve better vibration performance while reducing cost. 
     In the embodiment of the present disclosure, the piezoelectric ceramic plate can be selected by comprehensively considering factors such as vibration strength, cost, and drive voltage, so as to improve the performance of the touchpad. 
     As an example, the piezoelectric ceramic plate may be selected to have a length of 50 mm and a width of 6 mm. As an example, the piezoelectric ceramic plate is selected to have a length-width ratio of 50:6 as long as it can be applicable to a touch panel of an appropriate size and/or can meet a requirement for a certain vibration strength. For example, a piezoelectric ceramic plate having a length of 50 mm and a width of 6 mm is applicable to a touch panel having a length of 150 mm and a width of 90 mm. For example, the vibration feedback may be enhanced by adjusting the drive voltage without altering the size of the piezoelectric ceramic plate. 
     As an example of the embodiment of the present disclosure, the touchpad  100  may include one piezoelectric ceramic plate  104 . As an example, the piezoelectric ceramic plate  104  may be disposed at a center of the touch panel  101 . 
     For example, as shown in  FIG. 18 , the piezoelectric ceramic plate  104  is mounted in a direction parallel to a long side or a short side of the touch panel  101 . 
     For another example, as shown in  FIG. 19 , the piezoelectric ceramic plate  104  is mounted in a direction inclined to the long side or the short side of the touch panel  101 . 
     As an example, the touchpad  100  of the embodiment of the present disclosure may include a plurality of piezoelectric ceramic plates  104 , which may vibrate individually or together, thereby increasing consistency of vibration strength at different positions of the touch panel. 
     As an example, as shown in  FIGS. 20-22 , the plurality of piezoelectric ceramic plates are disposed parallelly side by side. In  FIG. 20 , two piezoelectric ceramic plates  104  are disposed side by side parallel to a short side of the touch panel  101 . In  FIG. 21 , two piezoelectric ceramic plates  104  are disposed side by side parallel to a long side of the touch panel  101 . In  FIG. 22 , four piezoelectric ceramic plates  104  are disposed side by side parallel to the short side of the touch panel  101 . 
     As an example, some of the plurality of piezoelectric ceramic plates  104  are disposed side by side parallel to a long side of the touch panel  101 , and other some of the plurality of piezoelectric ceramic plates  104  are disposed side by side parallel to a short side of the touch panel  101 . As shown in  FIG. 23 , the plurality of piezoelectric ceramic plates includes four piezoelectric ceramic plates  104 , which are disposed at edge positions of the four sides of the touch panel  101 , respectively. 
     In the embodiment of the present disclosure, the aforementioned sizes are provided by way of example, and are not intended to limit the embodiment of the present disclosure. 
     As an example of the embodiment of the present disclosure, the adhesive  131  may be a double-sided adhesive tape. The adhesive  132  may be a flexible glue or a glue pad. The adhesive  133  may be an instantaneous adhesive, an epoxy adhesive or an adhesive film. The adhesive  134  may be a double-sided adhesive tape or a glue. 
       FIG. 24  is a bottom view of an example of the touchpad according to the embodiment of the present disclosure, and  FIG. 25  is a bottom view of another example of the touchpad according to the embodiment of the present disclosure. 
       FIG. 24  is a bottom view of the touchpad  100  shown in  FIG. 3 . Compared with  FIG. 24 , the pressure sensors  102  is fixed beside the touch panel  101  by the elastic bracket  103  in  FIG. 25 , and the projection of the pressure sensor  102  on a plane where the touch panel  101  is located is outside a region of the touch panel  101 . 
     In an example, as shown in  FIG. 25 , the elastic bracket  103  may be of a U-shaped sheet structure including two short shafts fixed at an edge region below the touch panel  101  and one long shaft. The pressure sensor  102  is disposed on the short shafts. The long shaft extending along a side of the touch panel  101  such that the pressure sensor  102  is located on the plane where the touch panel  101  is located. 
     As an example, the elastic bracket  103  may also be of a semicircular sheet structure. 
     Herein, the shape of the elastic bracket  103  is not limited in the embodiment of the present disclosure. 
     Further, the pressure sensor  102  is disposed on the short shafts of the elastic bracket and at a position near the junctions of the short shafts and the long shaft. 
     Compared with  FIG. 25 , in another example, there is an included angle between the elastic bracket  103  and the touch panel  101 . In other words, the projection of the pressure sensor  102  on a plane where the touch panel  101  is located is outside a region of the touch panel  101 , while the pressure sensor  102  is not on the same plane where the touch panel  101  is located. 
     In the embodiment of the present disclosure, the pressure sensor is fixed beside of the touchpad, so that the thickness of the touch panel can be reduced, for example, the thickness of the touch panel may be 3 mm. 
     As an example of the embodiment of the present disclosure, the touchpad may include a plurality of elastic brackets  103 . For example, two elastic brackets  103  are provided and disposed opposite to each other, each of which is provided with two pressure sensors  102 . 
     The pressure sensor  102  is fitly attached to the elastic bracket  103 , and when the touch panel  101  is subjected to the pressure, the elastic bracket  103  is deformed together with the pressure sensor  102 , so that the pressure sensor  102  can convert the detected deformation into an electrical signal. 
       FIG. 26  is a structural exploded view of an example of the touchpad according to the embodiment of the present disclosure. The components shown in  FIG. 26  are consistent with those described above, and are not described herein for conciseness. 
       FIG. 27  is a schematic diagram of an example of interaction of internal structure of the touchpad according to the embodiment of the present disclosure. As shown in  FIG. 27 , a capacitance detection array below a touch panel converts a detected capacitance change into an electrical signal and sends the electrical signal to a touch detection unit in a control chip, and a pressure sensor below the touch panel converts a detected deformation signal into an electrical signal and sends the electrical signal to a pressure detection unit in the control chip, for example, a 4-channel piezoresistive detection unit. The control chip may communicate with a main control board in an electronic device through a communication unit. When the pressure detection unit determines that the pressure signal is greater than a first threshold, the control chip may communicate with a piezoelectric ceramic drive chip through the communication unit, and then the piezoelectric ceramic drive chip drives the piezoelectric ceramic plate to vibrate with the touch panel. 
     Optionally, the embodiments of the present disclosure further provide an electronic device including a touchpad according to various examples of the aforementioned embodiments. 
     It should be appreciated that references in the specification to “an embodiment”, “an example”, etc., indicate that the embodiment/example described may include a particular feature, structure, or characteristic, but every embodiment/example may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment/example. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment/example, it is submitted that it is within the knowledge of those skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments/examples whether or not explicitly described. 
     Those skill in the art will appreciate that the units and circuits of the examples described in the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may implement the described functions using different methods for each particular application, but such implementation should not be considered beyond the scope of the present disclosure. 
     In some of the examples of the embodiments provided herein, it should be understood that the disclosed circuits, branches thereof, and units may be implemented in other ways. For example, the branches described above are merely exemplary. For example, the division of the unit is merely a logical function division, and there may be another division manner in practical implementation. For example, a plurality of units or components may be combined or integrated into one branch, or some features may be ignored or not executed. 
     When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of the present disclosure essentially, or the part contributing to the prior art, or all or a part of the technical solutions may be implemented in the form of a software product. The software product is stored in a storage medium and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or a part of the steps of the methods described in the embodiments of the present disclosure. The foregoing storage medium includes: any medium that can store program code, such as a universal serial bus (USB) flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc. 
     Although the disclosure is illustrated and described herein with reference to specific embodiments, the disclosure is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the disclosure. Accordingly, the protection scope of the present disclosure shall prevail over the protection scope of the claims.