Touch detection circuit and display device

Abstract

The present application provides a touch detection circuit and a display device. The touch detection circuit comprises a piezoelectric ceramic sensor, a conductive member, a detection circuit and controllers; the piezoelectric ceramic sensor is arranged on a touch cover plate; the conductive member covers the piezoelectric ceramic sensor and is electrically connected to the piezoelectric ceramic sensor; the detection circuit is separately electrically connected to the conductive member and the piezoelectric ceramic sensor; the controllers are connected to the detection circuit; the detection circuit is configured to convert a charge change generated by the piezoelectric ceramic sensor into a voltage signal; and the controllers are configured to acquire a vibration signal and / or a pressure signal of the touch cover plate on the basis of the voltage signal.

Description

Touch detection circuit and display device

[0001] This application claims priority to Chinese Patent Application No. CN202411626008.9, filed on November 14, 2024, entitled “Touch Detection Circuit and Display Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of sensor technology, and more specifically, to a touch detection circuit and a display device. Background Technology

[0003] In the relevant technical field, when installing piezoelectric ceramic sensors onto touch cover plates, adhesive is required for bonding. However, the long curing time of the adhesive takes a lot of time and consumes a lot of tooling and fixture time, resulting in low production efficiency of display devices.

[0004] In related technical solutions, insulating tape is often used to pre-fix the piezoelectric ceramic sensor and the touch cover plate. However, this results in poor anti-interference ability of the touch detection circuit and poor detection accuracy of the piezoelectric ceramic sensor. Summary of the Invention

[0005] This application provides a touch detection circuit and a display device, which aims to replace insulating tape with conductive components and use the conductive components and conductive substrate to form a shielding layer. Combined with the touch detection circuit, it can improve the piezoelectric layer's ability to resist electromagnetic interference, thereby improving the detection accuracy of the piezoelectric ceramic sensor, simplifying the circuit design of the touch detection circuit, reducing the cost of the touch detection circuit, and thus reducing the cost of the display device.

[0006] This application provides a touch detection circuit, which includes a piezoelectric ceramic sensor, a conductive element, a detection circuit, and a controller. The piezoelectric ceramic sensor is disposed on a touch cover plate, the conductive element covers the piezoelectric ceramic sensor and is electrically connected to the piezoelectric ceramic sensor, the detection circuit is electrically connected to both the conductive element and the piezoelectric ceramic sensor, and the controller is connected to the detection circuit. The detection circuit converts the charge change generated by the piezoelectric ceramic sensor into a voltage signal, and the controller acquires the vibration signal and / or pressure signal of the touch cover plate based on the voltage signal.

[0007] Based on the above embodiments, a conductive component can be used to connect the piezoelectric ceramic sensor and the touch cover plate to position the piezoelectric ceramic sensor and the touch cover plate. This reduces the probability of the piezoelectric ceramic sensor moving relative to the touch cover plate after the tooling fixture is removed, improves the efficiency of the tooling fixture, and thus improves the production efficiency of the display device.

[0008] Furthermore, the use of conductive components to form a shielding layer can improve the piezoelectric ceramic sensor's resistance to electromagnetic interference, thereby improving the detection accuracy of the piezoelectric ceramic sensor, simplifying the circuit design of the touch detection circuit, and reducing the cost of the touch detection circuit.

[0009] When a user touches the touch cover, the piezoelectric ceramic sensor converts stress deformation into a change in charge. The detection circuit acquires the change in charge and converts it into a voltage signal. The controller can then acquire the vibration signal and / or pressure signal of the touch cover based on the voltage signal, and thus determine the touch point and the material of the object being touched based on the vibration and pressure signals.

[0010] In some embodiments, the piezoelectric ceramic sensor includes a conductive substrate, a positive piezoelectric layer, a ceramic body, a negative piezoelectric layer, and an insulating layer. The conductive substrate is used to bond with a touch cover plate. The positive piezoelectric layer is disposed on the side of the ceramic body away from the conductive substrate. The insulating layer at least covers the side of the positive piezoelectric layer away from the ceramic body. The negative piezoelectric layer is disposed on the side of the ceramic body facing the conductive substrate and is connected to the conductive substrate. A portion of the conductive element covers the side of the insulating layer away from the positive piezoelectric layer, and another portion of the conductive element covers the conductive substrate and is electrically connected to the conductive substrate. The detection circuit is electrically connected to the conductive element and the positive piezoelectric layer, respectively.

[0011] Based on the above embodiments, by setting an insulating layer on the side of the positive piezoelectric layer away from the ceramic body, and then using a conductive element to completely cover the side of the insulating layer away from the positive piezoelectric layer, the contact area between the conductive element and the piezoelectric ceramic sensor can be increased, thereby improving the connection stability between the conductive element and the piezoelectric ceramic sensor. This, in turn, can improve the connection stability between the piezoelectric ceramic sensor and the touch cover, thereby reducing the probability of the piezoelectric ceramic sensor moving relative to the touch cover.

[0012] Furthermore, when the conductive component is bonded to the conductive substrate, the conductive component will conduct electricity with the conductive substrate. This allows the conductive substrate and the conductive component to wrap around the piezoelectric ceramic sensor, forming a shielding layer to improve the piezoelectric ceramic sensor's resistance to electromagnetic interference. This, in turn, can improve the detection accuracy of the piezoelectric ceramic sensor, simplify the circuit design of the touch detection circuit, reduce the cost of the touch detection circuit, and thus reduce the cost of the display device.

[0013] When a user touches the touch cover, the piezoelectric ceramic sensor converts stress deformation into a change in charge between the positive and negative piezoelectric layers. The detection circuit acquires the change in charge and converts it into a voltage signal. The controller can then acquire the vibration and / or pressure signals of the touch cover based on the voltage signal, and thus determine the touch point and the material of the object being touched based on the vibration and pressure signals.

[0014] In some embodiments, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive element; or, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive element through the negative piezoelectric layer; or, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive element through a conductive substrate.

[0015] In some embodiments, the detection circuit includes a charge integrating circuit, a non-inverting amplifier circuit, and a discharge circuit. The charge integrating circuit is connected to a conductive element and a positive piezoelectric layer. The input terminal of the non-inverting amplifier circuit is connected to the output terminal of the charge integrating circuit, and the output terminal of the non-inverting amplifier circuit is connected to a controller. The output terminal of the discharge circuit is connected to the input terminal of the charge integrating circuit, and the controlled terminal of the discharge circuit is connected to the controller and controlled by the controller to discharge the piezoelectric ceramic sensor and the charge integrating circuit.

[0016] Based on the above embodiments, when a user touches the touch cover, the piezoelectric ceramic sensor converts stress deformation into a change in charge between the positive and negative piezoelectric layers. This change in charge is converted into a voltage signal by a charge integration circuit. The voltage signal is amplified by a non-inverting amplifier circuit and then acquired by the controller. This allows the controller to determine the user's touch position on the touch cover and the material used to touch it. In the event of abnormal conditions such as temperature drift in the detection circuit, the controller can activate the discharge circuit. This allows the charge integration circuit and the piezoelectric ceramic sensor to discharge, restoring them to a preset state. After the abnormal condition is resolved, the charge integration circuit and the non-inverting amplifier circuit can send the correct voltage signal to the controller, thereby improving the accuracy of the voltage signal acquired by the controller and consequently improving the accuracy of the touch position and touch material determined by the controller.

[0017] In some embodiments, the charge integrating circuit includes a first amplifier, a first capacitor, and a first resistor. The inverting input terminal of the first amplifier is connected to the positive piezoelectric layer, the non-inverting input terminal of the first amplifier is connected to a conductive element, and the non-inverting input terminal of the first amplifier is used to connect to a power supply. The positive power supply terminal of the first amplifier is used to connect to a power supply, the negative power supply terminal of the first amplifier is grounded, and the output terminal of the first amplifier is connected to the output terminal of the charge integrating circuit. The first plate of the first capacitor is connected to the inverting input terminal of the first amplifier, and the second plate of the first capacitor is connected to the output terminal of the first amplifier. The first end of the first resistor is connected to the first plate of the first capacitor, and the second end of the first resistor is connected to the second plate of the first capacitor.

[0018] Based on the above embodiments, the first resistor provides input bias current to the first amplifier to ensure its normal operation. When an abnormal charge change enters the first capacitor, the first capacitor discharges through the first resistor, eliminating the impact of the abnormal charge change on the voltage across the first capacitor. This reduces the impact of the abnormal charge change on the output signal of the first amplifier, improving the accuracy of the voltage signal at the output of the first amplifier. The first capacitor is an integrating capacitor and forms an analog integrator with the first amplifier. The analog integrator transfers and accumulates the charge output by the piezoelectric ceramic sensor into the first capacitor, thereby realizing the change in input charge and outputting a voltage signal. The voltage signal at the output of the first amplifier is linearly related to the charge between the two plates of the first capacitor.

[0019] In some embodiments, the charge integration circuit further includes a second resistor, the first end of which is connected to the positive piezoelectric layer, and the second end of which is connected to the inverting input of the first amplifier.

[0020] Based on the above embodiments, the second resistor is used to divide the change in charge entering the inverting input terminal of the first amplifier to limit the bandwidth of the charge integration circuit, and can adjust the phase of the charge integration circuit, thereby improving the loop stability of the charge integration circuit.

[0021] In some embodiments, the non-inverting amplifier circuit includes a third resistor, a fourth resistor, a second amplifier, and a fifth resistor. The first terminal of the third resistor is connected to the input terminal of the non-inverting amplifier circuit; the first terminal of the fourth resistor is used to connect to a power supply; the non-inverting input terminal of the second amplifier is connected to the second terminal of the third resistor, the inverting input terminal of the second amplifier is connected to the second terminal of the fourth resistor, the positive power supply terminal of the second amplifier is used to connect to a power supply, the negative power supply terminal of the second amplifier is grounded, and the output terminal of the second amplifier is connected to the output terminal of the non-inverting amplifier circuit; the first terminal of the fifth resistor is connected to the inverting input terminal of the second amplifier, and the second terminal of the fifth resistor is connected to the output terminal of the second amplifier.

[0022] Based on the above embodiments, the voltage signal output by the charge integration circuit is amplified by a non-inverting amplifier circuit composed of a third resistor, a fourth resistor, a second amplifier, and a fifth resistor, so as to improve the accuracy of the voltage signal acquired by the controller.

[0023] In some embodiments, the non-inverting amplifier circuit further includes a second capacitor, the first plate of which is connected to the inverting input terminal of the second amplifier, and the second plate of which is connected to the output terminal of the second amplifier.

[0024] Based on the above embodiments, the second capacitor can present low impedance to high-frequency noise, and the amplification factor of high-frequency noise can be selectively reduced by the fifth resistor. This allows the in-phase amplifier circuit to amplify low-frequency signals better, thereby improving the accuracy of the voltage signal acquired by the controller.

[0025] In some embodiments, the non-inverting amplifier circuit further includes a sixth resistor, the first end of which is connected to the output of the second amplifier, and the second end of which is connected to the output of the non-inverting amplifier circuit.

[0026] Based on the above embodiments, the sixth resistor can limit the current of the voltage signal output to the output terminal of the second amplifier, thereby reducing the probability of the controller being burned out by a large current, thus enabling the controller to have a longer service life, and consequently enabling the touch detection circuit to have a longer service life.

[0027] In some embodiments, the discharge circuit includes a first switching element, the input terminal of which is connected to a power supply, the controlled terminal of which is connected to the controlled terminal of the discharge circuit, and the output terminal of which is connected to the output terminal of the discharge circuit.

[0028] Based on the above embodiments, when abnormal conditions such as temperature drift occur in the detection circuit, the controller can send a conduction signal to the controlled terminal of the first switching element to enable conduction between the input and output terminals of the first switching element. This allows the charge integration circuit and the piezoelectric ceramic sensor to discharge using the discharge circuit, thereby restoring the charge integration circuit and the piezoelectric ceramic sensor to a preset state. After the abnormal condition of the detection circuit is resolved, the charge integration circuit and the in-phase amplifier circuit can send the correct voltage signal to the controller, thereby improving the accuracy of the voltage signal acquired by the controller and thus improving the accuracy of the touch position and touch material acquired by the controller.

[0029] In some embodiments, the discharge circuit further includes a seventh resistor, the first end of which is connected to the output of the first switching element, and the second end of which is connected to the output of the discharge circuit.

[0030] Based on the above embodiments, when the first switching element is turned on, the seventh resistor can limit the power supply current to prevent a large current from entering the inverting input terminal of the first amplifier, thereby reducing the probability of damage to the first amplifier and enabling the first amplifier to have a longer service life, which in turn enables the detection circuit to have a longer service life.

[0031] In some embodiments, the detection circuit further includes a 50Hz notch filter circuit, the input of which is connected to the output of the in-phase amplifier circuit, and the output of which is connected to the controller.

[0032] Based on the above embodiments, the voltage signal at the output of the non-inverting amplifier circuit can be filtered by the 50Hz notch filter circuit, which can also suppress power frequency noise and improve the accuracy of the voltage signal acquired by the controller.

[0033] This application also provides a display device, which includes a housing, a display module, a touch cover, a circuit board, and a touch detection circuit. The display module is connected to the housing; the touch cover and the display module are stacked on the housing; the circuit board is disposed inside the housing; and the touch detection circuit is disposed on the touch cover and electrically connected to the circuit board. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 is a schematic diagram of the structure of a display device in one embodiment of this application;

[0036] Figure 2 is a cross-sectional view of the touch cover, piezoelectric ceramic sensor and conductive component in one embodiment of this application.

[0037] Figure 3 is a cross-sectional view of the touch cover, piezoelectric ceramic sensor, heat insulation structure and conductive component in one embodiment of this application.

[0038] Figure 4 is a schematic diagram of the frame structure of the touch detection circuit in one embodiment of this application;

[0039] Figure 5 is a circuit diagram of a touch detection circuit in one embodiment of this application.

[0040] Explanation of reference numerals in the attached drawings: 1. Display device; 11. Housing; 12. Touch cover; 2. Touch detection circuit; 21. Piezoelectric ceramic sensor; 211. Conductive substrate; 212. Positive piezoelectric layer; 213. Ceramic body; 214. Negative piezoelectric layer; 215. Insulating layer; 216. Insulating sealant; 22. Conductive component; 23. Thermal insulation structure; 24. Detection circuit; 241. Charge integration circuit; 242. In-phase amplifier circuit; 243. Discharge circuit; 244. 50Hz notch filter circuit; 25. Controller; R1. First resistor; R 2. Second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; R8, eighth resistor; R9, ninth resistor; R10, tenth resistor; R11, eleventh resistor; R12, twelfth resistor; R13, thirteenth resistor; C1, first capacitor; C2, second capacitor; C3, third capacitor; C4, fourth capacitor; C5, fifth capacitor; C6, sixth capacitor; A1, first amplifier; A2, second amplifier; A3, third amplifier; Q1, first switching element. Embodiments of the present invention

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0042] In the relevant technical field, when installing piezoelectric ceramic sensors onto touch cover plates, adhesive is required for bonding. However, the long curing time of the adhesive takes a lot of time and consumes a lot of tooling and fixture time, resulting in low production efficiency of display devices.

[0043] In existing technologies, insulating tape is often used to pre-fix the piezoelectric ceramic sensor and the touch cover plate. However, this leads to a more complex touch detection circuit and higher production costs for the display device. In this embodiment, the insulating tape is replaced with a conductive component, and this conductive component forms a shielding layer with the conductive substrate. Combined with the touch detection circuit, this improves the piezoelectric ceramic sensor's resistance to electromagnetic interference, thereby enhancing its detection accuracy. It also simplifies the circuit design of the touch detection circuit, reducing its cost and ultimately lowering the cost of the display device.

[0044] Please refer to Figures 1-4. This application provides a display device 1, which includes a housing 11, a display module, a touch cover 12, a circuit board, and a touch detection circuit 2.

[0045] The housing 11 is used to mount the display module, touch cover 12, circuit board, and touch detection circuit 2, and can protect the display module, touch cover 12, circuit board, and touch detection circuit 2 to reduce the probability of damage to these components, thereby allowing the display device 1 to have a longer service life. For example, the housing 11 can be made of plastic or metal. In this embodiment, the material of the housing 11 is not specifically limited.

[0046] The display module can be at least one of CRT (Cathode Ray Tube) display, LED (Light-Emitting Diode) display, LCD (Liquid Crystal Display) display, and OLED (Organic Light-Emitting Diode) display. Of course, in other embodiments, the display module can also be in other forms. In this application embodiment, the specific form of the display module is not limited.

[0047] The touch cover 12 and the display module are stacked on the housing 11.

[0048] The touch detection circuit 2 is disposed on the touch cover plate 12 and is electrically connected to the circuit board.

[0049] Referring to Figures 1-4, in one embodiment, the touch detection circuit 2 includes a piezoelectric ceramic sensor 21, a conductive element 22, a detection circuit 24, and a controller 25.

[0050] The piezoelectric ceramic sensor 21 includes a conductive substrate 211, a positive piezoelectric layer 212, a ceramic body 213, and a negative piezoelectric layer 214. The conductive substrate 211 is bonded to the touch cover plate 12. The positive piezoelectric layer 212 is disposed on the side of the ceramic body 213 facing away from the conductive substrate 211, and the negative piezoelectric layer 214 is disposed on the side of the ceramic body 213 facing the conductive substrate 211. The negative piezoelectric layer 214 is connected to the conductive substrate 211. A high-modulus adhesive can be used to bond the conductive substrate 211 to the touch cover plate 12, thereby improving the connection stability between the touch cover plate 12 and the piezoelectric ceramic sensor 21, reducing the probability of the piezoelectric ceramic sensor 21 detaching from the touch cover plate 12, and thus improving the accuracy of the piezoelectric ceramic sensor 21 in detecting vibration and pressure signals from the touch cover plate 12. For example, the high-modulus adhesive can be, but is not limited to, epoxy adhesive or acrylic adhesive. In other embodiments, the high-modulus adhesive can also be other forms. In this embodiment of the application, no specific limitations are imposed.

[0051] It is understood that the touch detection circuit 2 may include multiple piezoelectric ceramic sensors 21, with adjacent piezoelectric ceramic sensors 21 spaced apart. The multiple piezoelectric ceramic sensors 21 disposed around the touch cover plate 12 can improve the accuracy of the piezoelectric ceramic sensors 21 in detecting vibration and pressure signals from the touch cover plate 12. In this embodiment, there are no specific limitations on the number of piezoelectric ceramic sensors 21 or their arrangement around the touch cover plate 12.

[0052] Referring to Figures 1 and 2, in one embodiment, since the time required for the adhesive to solidify after applying it between the conductive substrate 211 and the touch cover plate 12 is relatively long, in order to improve the production efficiency of the display device 1, the conductive substrate 211 and the touch cover plate 12 can be bonded together with adhesive tape to position the conductive substrate 211 and the touch cover plate 12. This reduces the probability of the conductive substrate 211 moving relative to the touch cover plate 12 after the tooling fixture is removed, thereby improving the production efficiency of the display device 1.

[0053] Furthermore, the positive piezoelectric layer 212 and the negative piezoelectric layer 214 can be piezoelectric silver layers to improve their conductivity. To reduce the oxidation rate of the positive piezoelectric layer 212, a liquid photoresist is also coated on the surface of the positive piezoelectric layer 212 of the piezoelectric ceramic sensor 21 to reduce the probability of the positive piezoelectric layer 212 coming into direct contact with air, thereby reducing the oxidation rate of the positive piezoelectric layer 212. Moreover, the liquid photoresist is an insulating material and can form an insulating layer 215 on the surface of the positive piezoelectric layer 212.

[0054] In this embodiment, the conductive substrate 211 and the touch cover plate 12 can be connected by a conductive element 22. The conductive element 22 is disposed on the side of the insulating layer 215 away from the positive piezoelectric layer 212 and connected to the touch cover plate 12, so that the piezoelectric ceramic sensor 21 can be sandwiched between the touch cover plate 12 and the conductive element 22, which can also achieve the pre-fixation of the piezoelectric ceramic sensor 21.

[0055] Furthermore, when the conductive element 22 comes into contact with the conductive substrate 211, the conductive element 22 will conduct electricity with the conductive substrate 211. Thus, the conductive substrate 211 and the conductive element 22 can be used to wrap the piezoelectric ceramic sensor 21 to form a wrapping shielding layer, thereby improving the ability of the piezoelectric ceramic sensor 21 to resist electromagnetic interference and thus improving the detection accuracy of the piezoelectric ceramic sensor 21.

[0056] It is understood that the conductive component 22 can be conductive adhesive tape, which is bonded to the side of the insulating layer 215 facing away from the positive piezoelectric layer 212 and to the touch cover plate 12 to achieve pre-fixation of the piezoelectric ceramic sensor 21. Since the conductive adhesive tape can be deformed arbitrarily, the contact area between the conductive adhesive tape and the piezoelectric ceramic sensor 21 can be increased to improve the connection stability between the conductive adhesive tape and the piezoelectric ceramic sensor 21, thereby improving the connection stability between the piezoelectric ceramic sensor 21 and the touch cover plate 12 and reducing the probability of the piezoelectric ceramic sensor 21 moving relative to the touch cover plate 12.

[0057] In other embodiments, the conductive element 22 can also be a metal element. The metal element is disposed on the side of the insulating layer 215 away from the positive piezoelectric layer 212 and is bonded to the touch cover plate 12. Similarly, the metal element and the conductive substrate 211 can be used to wrap the piezoelectric ceramic sensor 21 to form a shielding layer, thereby improving the ability of the piezoelectric ceramic sensor 21 to resist electromagnetic interference and thus improving the detection accuracy of the piezoelectric ceramic sensor 21. In the embodiments of this application, the specific form of the conductive element 22 is not limited.

[0058] Furthermore, the conductive element 22 can at least completely cover the side of the insulating layer 215 away from the positive piezoelectric layer 212, which can further improve the ability of the positive piezoelectric layer 212 to resist electromagnetic interference.

[0059] Referring to Figures 1 and 3, the touch detection circuit 2 further includes a thermal insulation structure 23. The thermal insulation structure 23 covers the side of the conductive element 22 facing away from the piezoelectric ceramic sensor 21, thereby stabilizing the temperature of the piezoelectric ceramic sensor 21 and reducing the impact of external temperature changes on the sensor, thus improving the detection accuracy of the piezoelectric ceramic sensor 21. Exemplarily, the material of the thermal insulation structure 23 may include at least one of expanded polystyrene (EPS), polyurethane foam (PU), rubber and plastic insulation materials, rock wool, glass wool, and silicate insulation materials. In other embodiments, the thermal insulation structure 23 may also be made of other materials.

[0060] It is understandable that the conductive component 22 can be integrally formed with the thermal insulation structure 23, and the assembly of the conductive component 22 and the thermal insulation structure 23 can be achieved through one installation. Compared with the separate assembly of the conductive component 22 and the thermal insulation structure 23, the assembly steps can be reduced and the assembly efficiency of the conductive component 22 and the thermal insulation structure 23 can be improved, thereby improving the production efficiency of the display device 1.

[0061] Referring to Figures 1-4, in one embodiment, the detection circuit 24 is electrically connected to the conductive element 22 and the piezoelectric ceramic sensor 21, respectively, and the controller 25 is connected to the detection circuit 24. The detection circuit 24 is used to convert the charge change generated by the piezoelectric ceramic sensor 21 into a voltage signal, and the controller 25 is used to acquire the vibration signal and / or pressure signal of the touch cover 12 based on the voltage signal. When the user touches the touch cover 12, the piezoelectric ceramic sensor 21 converts the stress deformation into a change in charge. The detection circuit 24 acquires the change in charge and converts it into a voltage signal. The controller 25 can acquire the vibration signal and / or pressure signal of the touch cover 12 based on the voltage signal, thereby acquiring the touch point and the material of the touch object based on the vibration signal and pressure signal.

[0062] Referring to Figures 1-4, in one embodiment, the positive terminal of the detection circuit 24 is electrically connected to the positive piezoelectric layer 212, and the negative terminal of the detection circuit 24 is electrically connected to the conductive element 22; it is used to convert the change in charge generated between the positive piezoelectric layer 212 and the negative piezoelectric layer 214 of the piezoelectric ceramic sensor 21 into a voltage signal; the controller 25 is connected to the detection circuit 24 and is used to obtain the vibration signal and pressure signal on the touch cover 12 according to the voltage signal, thereby obtaining the touch point and the material of the touch object for touching the touch cover 12 according to the vibration signal and pressure signal.

[0063] For example, the pen tip is made of a softer foamed PE material, the pen tail is made of a hard solid plastic material, and the finger is made of an even softer material. The vibration signal frequencies generated when different materials come into contact with the touch cover 12 are different. By analyzing the frequency components of the received vibration signal, the controller 25 can determine whether the current contact object is the pen tip, the pen tail, or a finger.

[0064] It is understood that in other embodiments, the positive terminal of the detection circuit 24 is electrically connected to the positive piezoelectric layer 212, and the negative terminal of the detection circuit 24 can also be electrically connected to the conductive element 22 through the negative piezoelectric layer 214.

[0065] It is understood that in other embodiments, the positive terminal of the detection circuit 24 is electrically connected to the positive piezoelectric layer 212, and the negative terminal of the detection circuit 24 can also be electrically connected to the conductive element 22 through the conductive substrate 211.

[0066] Referring to Figures 1-4, in one embodiment, the detection circuit 24 includes a charge integration circuit 241, a non-inverting amplifier circuit 242, and a discharge circuit 243. The charge integration circuit 241 is connected to the conductive element 22 and the positive piezoelectric layer 212. The input terminal of the non-inverting amplifier circuit 242 is connected to the output terminal of the charge integration circuit 241, and the output terminal of the non-inverting amplifier circuit 242 is connected to the controller 25. The output terminal of the discharge circuit 243 is connected to the input terminal of the charge integration circuit 241, and the controlled terminal of the discharge circuit 243 is connected to the controller 25 and controlled by the controller 25 to discharge the piezoelectric ceramic sensor 21 and the charge integration circuit 241.

[0067] When a user touches the touch cover 12, the piezoelectric ceramic sensor 21 converts stress deformation into a change in charge between the positive piezoelectric layer 212 and the negative piezoelectric layer 214. This change in charge is converted into a voltage signal by the charge integration circuit 241. The voltage signal is amplified by the in-phase amplifier circuit 242 and then acquired by the controller 25. This allows the controller 25 to determine the user's touch position on the touch cover 12 and the material used to touch it. If the detection circuit 24 experiences abnormal conditions such as temperature drift, the controller 25 can activate the discharge circuit 243. This allows the charge integration circuit 241 and the piezoelectric ceramic sensor 21 to discharge, restoring them to a preset state. After the abnormal condition is resolved, the charge integration circuit 241 and the in-phase amplifier circuit 242 can send the correct voltage signal to the controller 25, thereby improving the accuracy of the voltage signal acquired by the controller 25 and thus improving the accuracy of the touch position and touch material determined by the controller 25.

[0068] Furthermore, since the piezoelectric ceramic sensor 21 is wrapped with conductive substrate 211 and conductive element 22 in this embodiment to form a wrapping shielding layer, the ability of positive piezoelectric layer 212 to resist electromagnetic interference is improved, thereby improving the detection accuracy of piezoelectric ceramic sensor 21. This simplifies the circuit design of touch detection circuit 2, reduces the cost of touch detection circuit 2, and thus reduces the cost of display device 1.

[0069] Understandably, the controller 25 can sample the voltage signal output by the non-inverting amplifier circuit 242 through the analog-to-digital converter (ADC), which can reduce the data processing burden of the controller 25 and improve the data processing accuracy of the controller 25.

[0070] Referring to Figures 1-4, in one embodiment, the charge integration circuit 241 includes a first amplifier A1, a first capacitor C1, and a first resistor R1. The inverting input terminal of the first amplifier A1 is connected to the positive piezoelectric layer 212, the non-inverting input terminal of the first amplifier A1 is connected to the conductive element 22, and the non-inverting input terminal of the first amplifier A1 is used to connect to a power supply. The positive power supply terminal of the first amplifier A1 is used to connect to a power supply, the negative power supply terminal of the first amplifier A1 is grounded, and the output terminal of the first amplifier A1 is connected to the output terminal of the charge integration circuit 241. The first plate of the first capacitor C1 is connected to the inverting input terminal of the first amplifier A1, and the second plate of the first capacitor C1 is connected to the output terminal of the first amplifier A1. The first end of the first resistor R1 is connected to the first plate of the first capacitor C1, and the second end of the first resistor R1 is connected to the second plate of the first capacitor C1.

[0071] The first resistor R1 provides input bias current to the first amplifier A1 to ensure its normal operation. When an abnormal charge signal enters the first capacitor C1, the first capacitor C1 discharges through the first resistor R1, eliminating the influence of the abnormal charge signal on the voltage across the first capacitor C1. This reduces the impact of the abnormal charge signal on the output signal of the first amplifier A1, improving the accuracy of the voltage signal at the output of the first amplifier A1. The first capacitor C1 is an integrating capacitor and, together with the first amplifier A1, forms an analog integrator. The analog integrator transfers and accumulates the charge output by the piezoelectric ceramic sensor 21 into the first capacitor C1, thus achieving input charge signal and output voltage signal. The voltage signal at the output of the first amplifier A1 is linearly related to the amount of charge between the two plates of the first capacitor C1.

[0072] In this embodiment, the voltage of the power supply connected to the non-inverting input terminal of the first amplifier A1 can be a first voltage, and the voltage of the power supply connected to the positive power supply terminal of the first amplifier A1 can be a second voltage. The first voltage can be half of the second voltage, so that the positive signal acquisition range and the negative signal acquisition range of the first amplifier A1 are both large, thereby increasing the range of the input signal of the first amplifier A1. This improves the range of charge change access of the charge integration circuit 241, and thus improves the performance of the charge integration circuit 241. It is understood that the first voltage can also be one-quarter or one-eighth of the second voltage, which can be selected according to the actual circuit requirements. In this embodiment, no specific limitation is made.

[0073] Referring to Figures 2 and 3, it can be understood that in order to ensure a stable connection between the inverting input terminal of the first amplifier A1 and the positive piezoelectric layer 212, an insulating sealant 216 can be applied at the contact point. The insulating sealant 216 can prevent the positive piezoelectric layer 212 from conducting through the contact point with the conductive component 22, thereby improving the accuracy of the piezoelectric ceramic sensor 21 in converting vibration and pressure signals into changes in the amount of charge between the positive piezoelectric layer 212 and the negative piezoelectric layer 214, and improving the accuracy of judging the touch point of the touch cover 12 and the material of the touched object.

[0074] Referring to Figures 1-5, in one embodiment, the charge integration circuit 241 further includes a second resistor R2. The first end of the second resistor R2 is connected to the positive piezoelectric layer 212, and the second end of the second resistor R2 is connected to the inverting input terminal of the first amplifier A1. The second resistor R2 is used to divide the charge signal entering the inverting input terminal of the first amplifier A1 to limit the bandwidth of the charge integration circuit 241, and can adjust the phase of the charge integration circuit 241, thereby improving the loop stability of the charge integration circuit 241.

[0075] Referring to Figures 1-5, in one embodiment, the non-inverting amplifier circuit 242 includes a third resistor R3, a fourth resistor R4, a second amplifier A2, and a fifth resistor R5. The first end of the third resistor R3 is connected to the input terminal of the non-inverting amplifier circuit 242; the first end of the fourth resistor R4 is used to connect to the power supply; the non-inverting input terminal of the second amplifier A2 is connected to the second end of the third resistor R3, the inverting input terminal of the second amplifier A2 is connected to the second end of the fourth resistor R4, the positive power supply terminal of the second amplifier A2 is used to connect to the power supply, the negative power supply terminal of the second amplifier A2 is grounded, and the output terminal of the second amplifier A2 is connected to the output terminal of the non-inverting amplifier circuit 242; the first end of the fifth resistor R5 is connected to the inverting input terminal of the second amplifier A2, and the second end of the fifth resistor R5 is connected to the output terminal of the second amplifier A2. The non-inverting amplifier circuit 242, composed of the third resistor R3, the fourth resistor R4, the second amplifier A2, and the fifth resistor R5, amplifies the voltage signal output by the charge integrating circuit 241 to improve the accuracy of the voltage signal acquired by the controller 25.

[0076] Furthermore, the non-inverting amplifier circuit 242 also includes a second capacitor C2. The first plate of the second capacitor C2 is connected to the inverting input terminal of the second amplifier A2, and the second plate of the second capacitor C2 is connected to the output terminal of the second amplifier A2. The second capacitor C2 can present a low impedance to high-frequency noise, and the amplification factor of high-frequency noise can be selectively reduced through the fifth resistor R5. This allows the non-inverting amplifier circuit 242 to have a better amplification effect on low-frequency signals, thereby improving the accuracy of the voltage signal acquired by the controller 25.

[0077] Referring to Figures 1-5, in one embodiment, the non-inverting amplifier circuit 242 further includes a sixth resistor R6. The first end of the sixth resistor R6 is connected to the output terminal of the second amplifier A2, and the second end of the sixth resistor R6 is connected to the output terminal of the non-inverting amplifier circuit 242. The sixth resistor R6 can limit the current of the voltage signal output from the output terminal of the second amplifier A2, thereby reducing the probability of the controller 25 being burned out by a large current, thus enabling the controller 25 to have a longer service life, and consequently enabling the touch detection circuit 2 to have a longer service life.

[0078] Referring to Figures 1-5, in one embodiment, the discharge circuit 243 includes a first switching element Q1. The input terminal of the first switching element Q1 is connected to a power supply, the controlled terminal of the first switching element Q1 is connected to the controlled terminal of the discharge circuit 243, and the output terminal of the first switching element Q1 is connected to the output terminal of the discharge circuit 243. When abnormal conditions such as temperature drift occur in the detection circuit 24, the controller 25 can send a conduction signal to the controlled terminal of the first switching element Q1 to make the input and output terminals of the first switching element Q1 conduct, so that the charge integration circuit 241 and the piezoelectric ceramic sensor 21 can discharge using the discharge circuit 243. This allows the charge integration circuit 241 and the piezoelectric ceramic sensor 21 to return to a preset state, so that after the abnormal condition of the detection circuit 24 is resolved, the charge integration circuit 241 and the in-phase amplifier circuit 242 can send the correct voltage signal to the controller 25, thereby improving the accuracy of the voltage signal acquired by the controller 25, and thus improving the accuracy of the touch position and touch material acquired by the controller 25.

[0079] It is understood that the first switching element Q1 includes at least one of a bipolar junction transistor (BJT), a metal-oxide-semiconductor (MOS), and an electromagnetic relay. In the embodiments of this application, the specific form of the first switching element Q1 is not limited.

[0080] Referring to Figures 1-5, in one embodiment, the discharge circuit 243 further includes a seventh resistor R7. The first end of the seventh resistor R7 is connected to the output terminal of the first switching element Q1, and the second end of the seventh resistor R7 is connected to the output terminal of the discharge circuit 243. When the first switching element Q1 is turned on, the seventh resistor R7 can limit the power supply current to prevent a large current from entering the inverting input terminal of the first amplifier A1, thereby reducing the probability of damage to the first amplifier A1 and allowing it to have a longer service life. This, in turn, allows the detection circuit 24 to have a longer service life.

[0081] Understandably, in order to facilitate the restoration of the charge integration circuit 241 and the piezoelectric ceramic sensor 21 to their preset states, the voltage of the power supply connected to the input terminal of the first switching element Q1 is a third voltage, which can be the same as the first voltage. This ensures that the charge integration circuit 241 and the piezoelectric ceramic sensor 21 can be restored to their preset states, thereby improving the accuracy of the voltage signal that the charge integration circuit 241 and the non-inverting amplifier circuit 242 can send to the controller 25 after the discharge is completed.

[0082] Referring to Figures 1-5, in one embodiment, the detection circuit 24 further includes a 50Hz notch filter circuit 244. The input terminal of the 50Hz notch filter circuit 244 is connected to the output terminal of the in-phase amplifier circuit 242, and the output terminal of the 50Hz notch filter circuit 244 is connected to the controller 25. The voltage signal at the output terminal of the in-phase amplifier circuit 242 can be filtered by the 50Hz notch filter circuit 244, which can also suppress power frequency noise and improve the accuracy of the voltage signal acquired by the controller 25.

[0083] Please refer to Figures 1-5. Specifically, the 50Hz notch filter circuit 244 may include an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, and a third amplifier A3.

[0084] The first terminal of the eighth resistor R8 is connected to the input terminal of the 50Hz notch filter circuit 244; the first terminal of the ninth resistor R9 is connected to the second terminal of the eighth resistor R8; the first plate of the third capacitor C3 is connected to the second terminal of the eighth resistor R8, and the second plate of the third capacitor C3 is connected to the output terminal of the 50Hz notch filter circuit 244; the first plate of the fourth capacitor C4 is connected to the second terminal of the ninth resistor R9; the first plate of the fifth capacitor C5 is connected to the second plate of the fourth capacitor C4, and the second plate of the fifth capacitor C5 is connected to the second terminal of the ninth resistor R9; the first terminal of the tenth resistor R10 is connected to the second plate of the fourth capacitor C4, and the second terminal of the tenth resistor R10 is grounded; the third The non-inverting input of amplifier A3 is connected to the power supply through the eleventh resistor R11. The inverting input of the third amplifier A3 is connected to the second end of the ninth resistor R9 through the twelfth resistor R12. The positive power supply terminal of the third amplifier A3 is used to connect to the power supply, and the negative power supply terminal of the third amplifier A3 is grounded. The output terminal of the third amplifier A3 is connected to the output terminal of the 50Hz notch filter circuit 244. The first end of the thirteenth resistor R13 is connected to the inverting input terminal of the third amplifier A3, and the second end of the thirteenth resistor R13 is connected to the output terminal of the third amplifier A3. The first plate of the sixth capacitor C6 is connected to the input terminal of the 50Hz notch filter circuit 244, and the second plate of the sixth capacitor C6 is grounded.

[0085] Among them, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5 form a band-stop filter circuit; the third amplifier A3, the eleventh resistor R11, the twelfth resistor R12, and the thirteenth resistor R13 form an amplifier circuit to filter the voltage signal input to the controller 25, so as to suppress power frequency noise and improve the accuracy of the voltage signal acquired by the controller 25.

[0086] It is understood that, in the controller 25, after the analog-to-digital converter samples the voltage signal, a digital notch filter can be used to filter the sampled voltage signal, which can also achieve the effect of suppressing power frequency noise. In this embodiment, the specific form of the digital notch filter in the controller 25 is not limited.

[0087] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0088] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A touch detection circuit, wherein, The touch detection circuit includes a piezoelectric ceramic sensor, a conductive element, a detection circuit, and a controller. The piezoelectric ceramic sensor is disposed on the touch cover plate. The conductive element covers the piezoelectric ceramic sensor and is electrically connected to the piezoelectric ceramic sensor. The detection circuit is electrically connected to both the conductive element and the piezoelectric ceramic sensor. The controller is connected to the detection circuit. The detection circuit is configured to convert the charge change generated by the piezoelectric ceramic sensor into a voltage signal. The controller is configured to acquire the vibration signal and / or pressure signal of the touch cover plate based on the voltage signal.

2. The touch detection circuit of claim 1, wherein, The piezoelectric ceramic sensor includes: a conductive substrate, a positive piezoelectric layer, a ceramic body, a negative piezoelectric layer, and an insulating layer. The conductive substrate is bonded to the touch cover plate. The positive piezoelectric layer is disposed on the side of the ceramic body away from the conductive substrate. The insulating layer at least covers the side of the positive piezoelectric layer away from the ceramic body. The negative piezoelectric layer is disposed on the side of the ceramic body facing the conductive substrate and is connected to the conductive substrate. A portion of the conductive element covers the side of the insulating layer away from the positive piezoelectric layer, and another portion of the conductive element covers the conductive substrate and is electrically connected to the conductive substrate. The detection circuit is electrically connected to the conductive element and the positive piezoelectric layer, respectively.

3. The touch detection circuit of claim 2, wherein, The positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive component. Alternatively, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive component through the negative piezoelectric layer; Alternatively, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive component through the conductive substrate.

4. The touch detection circuit of claim 2, wherein, The detection circuit includes: A charge integration circuit is connected to the conductive element and the positive piezoelectric layer; A non-inverting amplifier circuit, wherein the input terminal of the non-inverting amplifier circuit is connected to the output terminal of the charge integrating circuit, and the output terminal of the non-inverting amplifier circuit is connected to the controller; and A discharge circuit is provided, the output of which is connected to the input of the charge integration circuit, and the controlled end of which is connected to the controller and controlled by the controller to discharge the piezoelectric ceramic sensor and the charge integration circuit.

5. The touch detection circuit of claim 4, wherein, The charge integration circuit includes: A first amplifier, wherein the inverting input terminal of the first amplifier is connected to the positive piezoelectric layer, the non-inverting input terminal of the first amplifier is connected to the conductive element, and the non-inverting input terminal of the first amplifier is configured to be connected to a power supply, the positive power supply terminal of the first amplifier is configured to be connected to a power supply, the negative power supply terminal of the first amplifier is grounded, and the output terminal of the first amplifier is connected to the output terminal of the charge integration circuit. A first capacitor, wherein the first plate of the first capacitor is connected to the inverting input terminal of the first amplifier, and the second plate of the first capacitor is connected to the output terminal of the first amplifier; and A first resistor, the first end of which is connected to the first plate of the first capacitor, and the second end of which is connected to the second plate of the first capacitor.

6. The touch detection circuit of claim 5, wherein, The charge integration circuit further includes: The second resistor has its first end connected to the positive piezoelectric layer and its second end connected to the inverting input of the first amplifier.

7. The touch detection circuit of claim 4, wherein, The in-phase amplifier circuit includes: The third resistor, the first end of which is connected to the input terminal of the non-inverting amplifier circuit; The fourth resistor, wherein the first end of the fourth resistor is configured to be connected to a power supply; A second amplifier, wherein the non-inverting input terminal of the second amplifier is connected to the second terminal of the third resistor, the inverting input terminal of the second amplifier is connected to the second terminal of the fourth resistor, the positive power supply terminal of the second amplifier is connected to the power supply, the negative power supply terminal of the second amplifier is grounded, and the output terminal of the second amplifier is connected to the output terminal of the non-inverting amplifier circuit; and The fifth resistor has its first end connected to the inverting input terminal of the second amplifier and its second end connected to the output terminal of the second amplifier.

8. The touch detection circuit of claim 7, wherein, The in-phase amplifier circuit further includes: A second capacitor, wherein the first plate of the second capacitor is connected to the inverting input terminal of the second amplifier, and the second plate of the second capacitor is connected to the output terminal of the second amplifier; and / or, The sixth resistor has its first end connected to the output terminal of the second amplifier and its second end connected to the output terminal of the non-inverting amplifier circuit.

9. The touch detection circuit of claim 4, wherein, The discharge circuit includes: A first switching element, wherein the input terminal of the first switching element is configured to be connected to a power supply, the controlled terminal of the first switching element is connected to the controlled terminal of the discharge circuit, and the output terminal of the first switching element is connected to the output terminal of the discharge circuit.

10. The touch detection circuit of claim 9, wherein, The discharge circuit further includes: The seventh resistor has its first end connected to the output terminal of the first switching element and its second end connected to the output terminal of the discharge circuit.

11. The touch detection circuit of claim 4, wherein, The detection circuit further includes: A 50Hz notch filter circuit, wherein the input terminal of the 50Hz notch filter circuit is connected to the output terminal of the in-phase amplifier circuit, and the output terminal of the 50Hz notch filter circuit is connected to the controller.

12. A display device, wherein, include: case; The display module is connected to the housing. A touch cover plate, which is stacked on the housing along with the display module; The circuit board is disposed within the housing; as well as The touch detection circuit as described in claim 1 is disposed on the touch cover plate and electrically connected to the circuit board.

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