Full transparent haptic actuator, manufacturing method, interactive screen prototype and driving method

Abstract

This invention relates to a fully transparent tactile actuator, its manufacturing method, an interactive screen prototype, and a driving method, belonging to the field of surface tactile interaction technology. It includes a glass substrate, an adhesion layer, a transparent conductive bottom electrode, a seed layer, a piezoelectric thin film layer, and a transparent conductive top electrode arranged sequentially. This invention discloses a fully transparent tactile actuator that can be directly integrated onto touchscreen glass, capable of simultaneously implementing both ultrasonic tactile and electrostatic hysteresis technologies, thereby achieving a wide range of friction coefficient adjustment for the tactile interactive display screen. This invention also provides a matching driving module with a wide range of adjustable voltage, frequency, amplitude, and waveform, and constructs a tactile interactive display screen prototype. This tactile screen can achieve a wide range of friction adjustment and supports tactile reproduction functions such as virtual buttons, virtual sliders, and virtual textures.

Description

Technical Field

[0001] This invention relates to tactile actuators, manufacturing methods, screen prototypes, and driving methods, and belongs to the field of surface tactile interaction technology. Background Technology

[0002] While visual and auditory interaction technologies are widely developed, tactile interaction is still in its initial stages. However, in application areas such as virtual reality, augmented reality, and human-computer interaction, which hold the promise of changing the future world, it is opening new channels for communication between humans and the virtual world. It not only brings a more realistic sense of immersion but also has the potential to propel human-virtual world interaction towards a new stage of three-dimensional integration of auditory, visual, and tactile senses. Therefore, the development of tactile reproduction methods and technologies represents an international trend and inevitable direction in the advancement of information technology.

[0003] Surface haptic technology aims to achieve virtual tactile reproduction on various physical interfaces. Two existing technical approaches exist: ultrasonic lubrication and electrostatic hysteresis. Ultrasonic virtual haptic technology, based on the friction control mechanism of ultrasonic lubrication, exhibits advantages such as high tactile reproduction, fast response speed, and rich local tactile variations in screen-based haptic rendering. The core driving element of this technology is a piezoelectric haptic actuator, which generates ultrasonic vibrations (Lamb standing wave A0 mode; amplitude > 1 μm; frequency > 25 kHz; wavelength < 15 mm) by driving the interactive interface. This induces the formation of a dynamic compressed air film between the fingertip and the surface, utilizing the lubrication effect of this air film to achieve precise control of the sliding friction coefficient. By spatiotemporally encoding the friction coefficient, various tactile effects such as button clicks, texture sensations, and sliding resistance can be simulated.

[0004] In contrast to ultrasonic lubrication, electrostatic stagnation induces charges on the front of the touchscreen glass by depositing transparent electrodes on the back of the screen and applying high voltage. When a finger slides across the charged interface, an electrostatic force is generated, creating a stagnation effect on the finger and increasing sliding friction.

[0005] Colgate et al. from Northwestern University integrated the aforementioned principle into the portable terminal TPAD Fire, enabling customizable textures to be displayed on the glass surface with a feedback force of up to 100 mN. However, this type of device generates friction only through vibration, has a small dynamic range, and requires the entire panel to vibrate. Furthermore, this device relies on only a single vibration feedback mode.

[0006] In their patent CN101632054A, titled "Vibrational Tactile Interface," M. Bier and colleagues from the University of Lille, France, fixed a piezoelectric array to a rectangular plate and used the high-frequency vibration of the piezoelectric array to generate an ultrasonic lubrication effect to achieve tactile feedback. Similarly, this device relies on only a single vibration feedback mode.

[0007] In their patent CN107122056A, titled "A Touchscreen Touch Point Positioning and Haptic Feedback System Based on Piezoelectric Effect," Sun Xiaoying et al. from Jilin University utilize the piezoelectric effect of the piezoelectric layer for time-division multiplexing, which can simultaneously realize touch point positioning and haptic reproduction functions. The piezoelectric layer is distributed in an array, which can also realize multi-point haptic feedback.

[0008] In patent CN104063054A, titled "A Tactile Reproduction Device and Method Based on Compressed Air Film Effect," Lu Xiong et al. from Nanjing University of Aeronautics and Astronautics disclosed a tactile reproduction device based on bidirectional frictional force control using ultrasonic lubrication and electrical stimulation. This device includes a piezoelectric ceramic excitation module and an electrode array excitation module. However, both the piezoelectric ceramic and electrodes in this device are made of opaque materials, making them unsuitable for touchscreens.

[0009] The invention disclosed in CN108227979A, entitled "System and Method for Compliant Illusion with Tactile Sensation," involves receiving sensor signals from a sensor; determining user interaction with a virtual object; determining a tactile effect based in part on the sensor signals and user interaction; and sending a tactile signal associated with the tactile effect to a tactile output device. However, it does not specify the type of actuator, limiting its application to a theoretical level.

[0010] Regarding piezoelectric haptic actuators, the aforementioned devices all employ bulk piezoelectric ceramics, with a material thickness of several millimeters and opaque, resulting in driving voltages exceeding 100 V. Furthermore, their lack of transparency makes them unsuitable for highly integrated haptic interactive displays. In terms of driving parameters, these devices operate in a single-frequency, single-mode manner, failing to achieve a wide range of voltage and frequency conversions, nor the amplitude and waveform modulation required for complex virtual textures.

[0011] The new generation of screen displays places higher demands on integration and full-screen display. Traditional ceramic haptic actuators suffer from problems such as opacity, thickness, and bulkiness, making miniaturization difficult and incompatible with transparent display screens. In addition, ceramic haptic actuators, as standalone components, are costly and difficult to integrate directly.

[0012] Therefore, there is an urgent need to propose a fully transparent tactile actuator, manufacturing method, interactive screen prototype, and driving method to solve the above-mentioned technical problems. Summary of the Invention

[0013] To address the aforementioned problems, a fully transparent haptic actuator, a manufacturing method, an interactive screen prototype, and a driving method are provided. A brief overview of the invention is given below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0014] The technical solution of the present invention: The fully transparent tactile actuator includes a glass substrate, an adhesive layer, a transparent conductive bottom electrode, a seed crystal layer, a piezoelectric thin film layer, and a transparent conductive top electrode arranged in sequence.

[0015] Preferably, the transparent conductive top electrode, the piezoelectric thin film layer, and the transparent conductive bottom electrode together constitute a piezoelectric tactile actuator, and the transparent conductive bottom electrode and the glass substrate together constitute an electrostatic actuator.

[0016] Preferably, the glass substrate is alkali-free aluminoborosilicate glass with a thickness of 0.3–0.5 mm; The transparent conductive bottom electrode is made of fluorine-doped tin oxide, bismuth-doped tin oxide, or tin-doped indium oxide, with a conductivity greater than 3000 S·cm. - ¹.

[0017] Preferably, the adhesion layer material is hafnium oxide, titanium dioxide, aluminum oxide, or magnesium oxide, and the thickness is 10–20 nm; The seed crystal layer is a lead titanate thin film with a thickness of 10–20 nm. The piezoelectric thin film layer is made of lanthanum-doped lead zirconate titanate, with a thickness of 1–2 μm and a piezoelectric coefficient e. 31,f Greater than or equal to 8 C·m -2 The lanthanum doping concentration in PLZT is 0.5–2 mol%; The transparent conductive top electrode is made of fluorine-doped tin oxide, tin-doped indium oxide, or gallium-doped zinc oxide, with a conductivity greater than 3000 S·cm. - ¹.

[0018] A method for manufacturing a fully transparent haptic actuator, comprising the following steps: Provide glass substrates; An adhesion layer is deposited on the glass substrate; A transparent conductive bottom electrode is deposited on the adhesion layer; A seed layer is deposited on the transparent conductive bottom electrode; A piezoelectric thin film layer is deposited on the seed crystal layer; A transparent conductive top electrode is deposited on the piezoelectric thin film layer.

[0019] Preferably, the adhesion layer is deposited by atomic layer deposition and annealed at 600–800°C; The transparent conductive bottom electrode and transparent conductive top electrode are deposited by magnetron sputtering and annealed at 600°C in an oxygen atmosphere. The seed crystal layer and piezoelectric thin film layer are deposited by sol-gel method and subjected to multi-stage heating and annealing treatment.

[0020] An interactive screen prototype, comprising the aforementioned fully transparent haptic actuator, including: The touchscreen module includes: a screen and a piezoelectric drive module for detecting external signals; The host computer is used to receive external signals and generate drive parameters; The driving module includes: a lower-level machine, a boost circuit, and an H-bridge circuit, used to generate driving signals according to driving parameters and apply them to the fully transparent tactile actuator; The driver module also includes a step-down circuit to provide low-voltage power to the host computer and MCU.

[0021] Preferably, the prototype also includes a pressure sensing module for detecting external pressure and forming a closed-loop feedback. The boost circuit is a type of boost circuit used to convert low-voltage DC to high-voltage DC up to 200V; the H-bridge circuit is used to convert high-voltage DC to high-frequency AC signals.

[0022] The driving method for the interactive screen prototype, based on the interactive screen prototype, includes the following steps: The touchscreen detects the position of a finger sliding on the screen. The main controller determines the target friction coefficient for the current area based on a preset friction coefficient mapping table; Main controller selects the working mode: Mode 1 is ultrasonic lubrication mode, and Mode 2 is electrostatic stagnation mode; The main controller sends drive parameters to the lower-level MCU; The MCU generates a PWM signal to drive the boost circuit and H-bridge circuit, and outputs a drive signal to the fully transparent haptic actuator. Piezoelectric or electrostatic actuators respond to drive signals and adjust the sliding friction between the finger and the screen.

[0023] Preferred mode: In mode one, the driving signal is a high-frequency AC voltage with a frequency of 25 kHz to 100 kHz and a peak voltage of 20 V to 120 V, and the waveform is a sine wave, square wave, or amplitude-modulated wave; In mode two, the driving signal is an AC voltage of 50 V to 200 V, applied between the transparent conductive bottom electrode and the front side of the glass substrate, and the thickness of the glass substrate is no more than 0.5 mm.

[0024] The present invention has the following beneficial effects: This invention discloses a fully transparent tactile actuator that can be directly integrated onto touchscreen glass, which can simultaneously realize both ultrasonic tactile and electrostatic hysteresis technologies, thereby achieving a wide range of friction coefficient adjustment for tactile interactive display screens.

[0025] The present invention also provides a matching wide-range voltage, frequency adjustable, amplitude and waveform adjustable driving module, and constructs a prototype of a tactile interactive display screen.

[0026] This tactile screen allows for a wide range of friction adjustment and supports tactile reproduction functions such as virtual buttons, virtual sliders, and virtual textures. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the fully transparent tactile actuator of the present invention.

[0028] Figure 2 This is a scanning electron microscope image of the fully transparent tactile actuator of the present invention.

[0029] Figure 3 Ferroelectric hysteresis curve of PLZT thin film.

[0030] Figure 4 This is a schematic diagram of a haptic interactive display screen prototype.

[0031] Figure 5 This is a schematic diagram illustrating the working principle of a tactile interactive display screen prototype.

[0032] Figure 6 Vibration mode diagram for a piezoelectric actuator driving a touchscreen glass.

[0033] Figure 7 In working mode one, the piezoelectric actuator periodically adjusts the sliding friction force under 1 Hz rectangular wave amplitude modulation.

[0034] Figure 8 In working mode one, the piezoelectric actuator periodically adjusts the sliding friction force under 1 Hz sinusoidal amplitude modulation. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0036] Specific implementation method one: Combining Figure 1 This embodiment describes a fully transparent tactile actuator, which includes a glass substrate 7, an adhesion layer 6, a transparent conductive bottom electrode 5, a seed crystal layer 4, a piezoelectric thin film layer 3, and a transparent conductive top electrode 2 arranged sequentially. This invention develops a tactile actuator compatible with a display screen and manufactures a tactile interactive display screen with adjustable friction.

[0037] Specific Implementation Method Two: Combining Figure 1This embodiment describes a fully transparent tactile actuator, which includes: Glass substrate 7 (tactile glass); An adhesion layer 6 deposited on the glass substrate 7; A transparent conductive bottom electrode 5 deposited on the adhesion layer 6; Seed layer 4 deposited on the transparent conductive bottom electrode 5; A piezoelectric thin film layer 3 is deposited on the seed crystal layer 4; A transparent conductive top electrode 2 deposited on the piezoelectric thin film layer 3; The transparent conductive top electrode 2, the piezoelectric thin film layer 3, and the transparent conductive bottom electrode 5 together constitute a piezoelectric tactile actuator, while the transparent conductive bottom electrode 5 and the glass substrate 7 together constitute an electrostatic actuator. This tactile actuator structure can simultaneously realize two friction force control mechanisms. Among them, the top electrode, the piezoelectric thin film, and the bottom electrode together constitute a piezoelectric tactile actuator, which can reduce the sliding friction coefficient of the touch screen glass surface by utilizing the ultrasonic lubrication principle; the transparent bottom electrode and the glass substrate itself constitute an electrostatic actuator, which can enhance the sliding friction coefficient of the touch screen glass surface based on the electrostatic stagnation principle. The visible light transmittance of the fully transparent tactile actuator is ≥75%.

[0038] Specific implementation method three: Combining Figure 1 This embodiment describes a fully transparent tactile actuator, wherein the glass substrate 7 is made of alkali-free aluminoborosilicate glass with a thickness of 0.3–0.5 mm. The transparent conductive bottom electrode 5 is made of fluorine-doped tin oxide (FTO), bismuth-doped tin oxide (BTO), or tin-doped indium oxide (ITO), with a conductivity greater than 3000 S·cm. - ¹.

[0039] Specific implementation method four: Combination Figure 1 This embodiment describes a fully transparent tactile actuator where the bottom electrode adhesion layer 6 is made of hafnium oxide (HfO2), titanium dioxide (TiO2), aluminum oxide (Al2O3), or magnesium oxide (MgO), with a thickness of 10–20 nm and a light transmittance of 90%. The seed layer 4 is a lead titanate (PTO) thin film with a thickness of 10–20 nm; The piezoelectric thin film layer 3 is made of lanthanum-doped lead zirconate titanate (PLZT), with a thickness of 1–2 μm and a piezoelectric coefficient e. 31,f Greater than or equal to 8 C·m -2The lanthanum doping concentration in PLZT is 0.5–2 mol%, which can effectively improve the piezoelectric properties of intrinsic PZT films. Piezoelectric films are the core functional materials of piezoelectric tactile actuators, and their thickness is optimal at 1–2 μm. Excessive thickness can lead to excessive stress between the film and the bottom electrode, while excessive thinness can affect performance due to insufficient effective piezoelectric material mass. The transparent conductive top electrode 2 is made of fluorine-doped tin oxide (FTO), tin-doped indium oxide (ITO), or gallium-doped zinc oxide (GZO), with a conductivity greater than 3000 S·cm. - ¹; The materials for each layer, from top to bottom, are as follows: The transparent top electrode is made of fluorine-doped tin oxide (FTO) thin film or tin-doped indium oxide (ITO) thin film; the material of the transparent top electrode is fluorine-doped tin oxide (FTO) thin film, tin-doped indium oxide (ITO) thin film, or gallium-doped zinc oxide (GZO) thin film, with a conductivity greater than 3000 S·cm. - ¹; The transparent bottom electrode uses a tin oxide-based transparent conductive film with a conductivity greater than 3000 S·cm. - ¹; The deposition process of the bottom electrode material is compatible with that of the piezoelectric thin film, and there is no alkali metal diffusion problem between the electrode and the piezoelectric layer; Piezoelectric thin film, using lanthanum-doped PZT (PLZT); The seed layer is made of lead titanate (PTO). The transparent bottom electrode is made of fluorine-doped tin oxide (FTO) thin film or bismuth-doped tin oxide thin film; Hafnium oxide (HfO2) adhesion layer; Glass substrate; The thicknesses of the aforementioned thin films are 100 nm, 1 μm, 200 nm, 20 nm, and 0.5 mm, respectively. The overall visible light transmittance of the device exceeds 75%, without affecting the user's visual interaction with the display screen. A transparent actuator array is integrated on both sides of the back of an alkali-free glass (SCHOTT AF 32® eco) substrate; this alkali-free aluminoborosilicate glass can be used as a cover glass for display screens.

[0040] Specific Implementation Method Five: Combining Figure 1-3 This embodiment describes a method for manufacturing a fully transparent tactile actuator, which includes the following steps: S1: Provides glass substrate 7; S2: Deposit an adhesion layer 6 on the glass substrate 7; S3: Deposit a transparent conductive bottom electrode 5 on the adhesion layer 6; S4: Deposit a seed crystal layer 4 on the transparent conductive bottom electrode 5; S5: Deposit a piezoelectric thin film layer 3 on the seed crystal layer 4; S6: Deposit a transparent conductive top electrode 2 on the piezoelectric thin film layer 3; S7: The surface of the transparent conductive top electrode 2 is covered with a photoresist protective layer 1.

[0041] Specific Implementation Method Six: Combination Figure 1-3 This embodiment describes the manufacturing method of the fully transparent tactile actuator. In S2, the adhesive layer is deposited by atomic layer deposition and annealed at 600-800°C. In S3 and S6, the transparent conductive bottom electrode 5 and the transparent conductive top electrode 2 are deposited by magnetron sputtering and annealed at 600°C in an oxygen atmosphere. In S4, the seed crystal layer 4 and the piezoelectric thin film layer 3 are deposited by the sol-gel method and subjected to multi-level gradient heating at a temperature of 130℃-700℃. The optimized multi-level gradient heating includes drying at 150℃ and pre-firing at 300℃; and two-step rapid annealing crystallization at a heating rate of 50℃ / min, first heating to 400℃ for pre-crystallization, and then heating from 400℃ to 700℃ to achieve final crystallization.

[0042] Specific implementation method seven: Combining Figure 1-6 The interactive screen prototype of this embodiment includes a fully transparent haptic actuator, comprising: The capacitive touchscreen module and touchscreen driver module include: a screen and a signal processing circuit for detecting external signals (finger sliding position); the signal processing circuit is connected to a pressure sensor, and the host computer processes the pressure signal; the pressure sensor is actually the capacitive screen itself. The host computer is used to receive external signals (position information) and generate drive parameters; The tactile actuator driving module includes: a lower-level MCU, a boost circuit, and an H-bridge circuit. The tactile actuator driving module is connected to the fully transparent tactile actuator and is used to generate driving signals according to driving parameters and apply them to the fully transparent tactile actuator. The prototype uses a piezoelectric module (tactile actuator) to achieve ultrasonic lubrication mode to reduce friction, or uses an electrostatic actuator to achieve electrostatic stagnation mode to increase friction. The tactile actuator drive module also includes a step-down circuit for providing low-voltage power to the host computer and MCU.

[0043] Specific implementation method eight: Combination Figure 1-6 The interactive screen prototype of this embodiment is described. The touch screen module of the prototype also includes a pressure sensing module for detecting external pressure and forming closed-loop feedback. The boost circuit is used to convert low-voltage DC to high-voltage DC up to 200V; the H-bridge circuit is used to convert high-voltage DC to high-frequency AC signals. The screen surface serves as the input for interaction; The piezoelectric drive module receives the high-frequency AC drive signal from the lower-level drive module and drives the screen in reverse to achieve tactile feedback. The pressure sensing module collects external pressure signals and transmits them to the sensing signal processing circuit. The pressure sensor module essentially includes the capacitive screen itself and the pressure sensor. The capacitive screen provides feedback on the finger position. The pressure sensor detects the amount of pressure applied by the finger on the touch screen. This electrical signal is transmitted to the host computer through the sensing signal processing circuit. The host computer then provides feedback to the drive module, which achieves positioning and compensates for finger pressure. The sensor signal processing circuit amplifies, modulates, demodulates, and performs AD conversion on the pressure signal, and transmits the processed data to the host computer. The pressure sensing module and the sensor signal processing circuit form a closed-loop control, which realizes tactile accuracy and adaptability, and is easy to promote and apply. The host computer outputs images to the screen display module for real-time display via the screen display driver; and uses tactile signal feedback to control the lower-level machine of the driver module through data communication with the host computer. The lower-level machine receives instructions from the upper-level machine and outputs PWM1 / PWM2 to control the Boost circuit / H-bridge circuit of the drive module; The DC power supply powers the host computer, screen display driver, sensor signal processing circuit, and screen module, and the driver module is powered through a step-down circuit. The Boost circuit generates high-voltage DC, which is then inverted into high-voltage AC by the H-bridge circuit to drive the piezoelectric drive module. This invention discloses a fully transparent tactile actuator that can be directly integrated onto touchscreen glass, capable of simultaneously implementing both ultrasonic tactile and electrostatic hysteresis technologies, thereby achieving a wide range of friction coefficient adjustment for tactile interactive display screens. The invention also provides a matching drive module with adjustable voltage, frequency, amplitude, and waveform, and constructs a prototype tactile interactive display screen. This tactile screen can achieve a wide range of friction force adjustment and supports tactile reproduction functions such as virtual buttons, virtual sliders, and virtual textures.

[0044] Specific Implementation Method Nine: Combining Figure 1-8The driving method of the interactive screen prototype in this embodiment is described. Based on the interactive screen prototype, the design of the haptic interactive display screen prototype is as follows: The hardware part includes a cover glass integrating a haptic actuator, a capacitive touch screen, a touch screen control module, a main controller (host computer), a haptic actuator driving module (including a main controller (slave computer), a buck circuit, a boost circuit, and an H-bridge circuit), and a 3D printed shell; the software part includes an algorithm for programming the friction force of objects in the displayed image, and an algorithm for emitting haptic actuator driving signals in real time according to the finger position; the driving method includes the following steps: The touchscreen detects the position of a finger sliding on the screen. The main controller determines the target friction coefficient for the current area based on a preset friction coefficient mapping table; Main controller selects the working mode: Mode 1 is ultrasonic lubrication mode, and Mode 2 is electrostatic stagnation mode; The main controller sends drive parameters to the lower-level MCU; The MCU generates a PWM signal to drive the boost circuit and H-bridge circuit, and outputs a drive signal to the fully transparent haptic actuator. Piezoelectric or electrostatic actuators respond to drive signals and adjust the sliding friction between the finger and the screen.

[0045] Specific Implementation Method Ten: Combining Figure 1-8 The driving method of the interactive screen prototype in this embodiment is described. When the tactile actuator works as a piezoelectric tactile actuator based on the ultrasonic lubrication principle, an AC voltage is applied to the top electrode and the bottom electrode is grounded. This working mode is defined as mode one. In mode one, the driving signal is a high-frequency AC voltage with a frequency of 25 kHz to 100 kHz and a peak voltage of 20 V to 120 V, and the waveform is a sine wave, square wave, or amplitude-modulated wave. When the working mode is mode one, the piezoelectric haptic actuator drives the touch screen glass to vibrate ultrasonically, and the vibration mode is Lamb wave A0 mode; thus producing an ultrasonic lubrication effect on the touch screen glass surface. When the tactile actuator works as an electrostatic actuator based on the principle of electrostatic hysteresis, an AC voltage is applied to the bottom electrode and the front of the glass is grounded. This working mode is defined as mode two. In mode two, the driving signal is an AC voltage of 50 V to 200 V, applied between the transparent conductive bottom electrode and the front side of the glass substrate, and the thickness of the glass substrate is no more than 0.5 mm. When the working mode is mode two, the electrostatic actuator causes the touch screen glass surface to generate an electrostatic adsorption effect, which creates a stabilizing effect on the sliding finger and increases the sliding friction. The prototype renders the tactile effects of virtual knobs, virtual sliders, or virtual textures in real time. The virtual textures are achieved by modulating the amplitude or frequency of the drive signal in mode 1. The specific working method is as follows: First, under mode one conditions, measure the friction force f when a finger slides on the touchscreen glass under different voltages, frequencies, and waveforms. The relative friction coefficient μ = f0 / f under different driving signals was obtained. A dataset of relative friction coefficients was established; similarly, under mode two conditions, the frictional force f during finger sliding under different voltages was measured. The corresponding relative friction coefficient μ = f0 / f is obtained. The software establishes a corresponding dataset. It defines the relative friction coefficient of objects in the displayed images on the screen in a regionalized manner, monitors the finger's sliding position through the capacitive screen, and outputs corresponding drive signals in real time based on the friction coefficient defined at the position. Specifically, when a user applies external pressure to the screen surface, the pressure sensing module converts the pressure signal into an electrical signal and outputs it to the sensing signal processing circuit. After amplification, modulation, demodulation, and analog-to-digital conversion, the signal is transmitted to the main controller. The main controller generates control commands based on the processed tactile signals and feeds them back to the screen display driver to achieve synchronization between image display and tactile interaction. On the other hand, it sends the drive parameters to the lower-level MCU via data communication. The MCU outputs PWM signals according to the control commands, which drive the Boost circuit and H-bridge circuit respectively, converting the DC power supply into a high-frequency AC drive signal and applying it to the piezoelectric actuator and electrostatic actuator. The piezoelectric drive module applies high-frequency vibration to the screen surface, thereby regulating the interface friction characteristics and achieving controllable tactile feedback. At the same time, the system achieves coordinated regulation of tactile perception and drive output through a closed-loop signal feedback mechanism, completing the integrated operation of screen display and tactile feedback. It is worth noting that when the tactile actuator of the present invention is in mode two, it is only suitable for thinner glass with a thickness of no more than 0.5 mm.

[0046] The prototype can effectively render virtual knobs, sliders, and textures.

[0047] Example 1: Figure 1 An implementation of a haptic actuator is shown. The haptic actuator includes a touch screen glass 7, a bottom electrode adhesion layer 6, a transparent conductive bottom electrode 5, a piezoelectric thin film seed layer 4, a piezoelectric thin film layer 3, a transparent conductive top electrode 2, and a photoresist protective layer 1.

[0048] The thin film layer is the core layer of the piezoelectric tactile actuator, while the bottom electrode is the core layer of the electrostatic actuator.

[0049] To ensure compatibility with the deposition process of PLZT piezoelectric thin films, the touchscreen glass 7 is made of high-temperature resistant, alkali-free glass. The thickness can be 0.3-0.5 mm.

[0050] The bottom electrode adhesion layer 6 is mainly to facilitate better adhesion of the transparent bottom electrode to the glass and to prevent interdiffusion of metal ions during subsequent high-temperature annealing. In this invention, a 10-20 nm thick HfO2 layer is selected. Generally, TiO2, Al2O3, and MgO can also be used as the adhesion layer. Typically, HfO2 exhibits higher light transmittance. This layer is deposited on the glass substrate using atomic layer deposition (ALD) technology, and then annealed at 600-800 °C after deposition.

[0051] The transparent conductive bottom electrode 5 is made of tin oxide-based material, such as FTO or BTO. This is mainly because there is no diffusion between the tin oxide-based material and the piezoelectric layer. The electrode conductivity is greater than 3000 S / cm. -1 This layer was deposited on the adhesion layer using magnetron sputtering technology, and then annealed at 600 °C in an oxygen atmosphere after deposition.

[0052] PTO piezoelectric seed layer 4 is mainly used to assist in the growth of PLZT films, enhancing their crystallinity and piezoelectric properties. Its thickness is between 10-20 nm. This layer is deposited on the bottom electrode using the sol-gel method. After deposition, the film is first heated at 130 °C in air for 3 minutes, then at 400 °C for 3 minutes, and finally heated to 700 °C in a rapid heating annealing furnace. These temperature parameters are experimental settings; actual temperatures may deviate by 10-20 °C.

[0053] Piezoelectric thin film layer 3, the PLZT piezoelectric thin film layer, is the core functional material of the piezoelectric tactile actuator. Its stoichiometry is Pb. 0.9 La 0.1 Zr 0.53 Ti 0.47 O3. The thickness is approximately 1 μm. This layer was deposited on the PTO seed layer using the sol-gel method. After deposition, it was first heated in air at 130 °C for 3 minutes; then heated at 400 °C for 3 minutes; finally, it was heated in a rapid heating annealing furnace at 400 °C for 3-5 minutes, followed by 700 °C for 5 minutes. These temperature parameters were set for the experiment, and the actual temperature may deviate by 10-20 °C.

[0054] The transparent conductive top electrode 2 is made of tin oxide-based material, such as FTO. The electrode conductivity is greater than 3000 S / cm. -1 This layer was deposited on the adhesion layer using magnetron sputtering technology, and then annealed at 600 °C in an oxygen atmosphere. Patterned deposition was achieved using photolithography, and a piezoelectric haptic actuator was constructed on the touchscreen glass along with the PLZT piezoelectric layer and a transparent conductive bottom electrode.

[0055] The photoresist protective layer 1 is mainly used to protect the top electrode and prevent it from being damaged during prototype integration. SU8 photoresist is used for the protective layer. It is patterned and applied to the surface of the top electrode using photolithography.

[0056] Scanning electron microscope image of the cross-section of the tactile actuator as shown in Figure 1 Figure 2 As shown. Displayed with Figure 1 The microstructure diagrams for each layer are shown. Due to the thinness of the adhesion layer 6 and seed layer 4, they are not clearly visible. The columnar grain structure and dense microstructure of the PLZT piezoelectric layer 3 are clearly visible, and its surface exhibits high orientation. This is the source of its high-voltage piezoelectric properties.

[0057] Figure 3 This is the ferroelectric hysteresis curve of the PLZT thin film, with a saturation polarization value reaching 45 μC cm⁻¹. -1 The residual polarization value reaches 20 μC cm. -1 piezoelectric coefficient e 31,f Reaching 8 cm -2 .

[0058] Figure 4 The implementation of a haptic interactive display screen prototype is demonstrated. The prototype includes an integrated cover glass 7, a transparent conductive bottom electrode layer (electrostatic actuator functional layer) 6, a piezoelectric actuator functional layer 8, a capacitive touch screen and touch screen driving module 9, a main controller 10, and a haptic actuator driving module 11.

[0059] The cover glass is made of alkali-free aluminoborosilicate glass (SCHOTT AF 32® eco) with a thickness of 0.3-0.5 mm, serving both display protection and haptic actuator support functions. The haptic actuator is integrated into both sides of the back of the glass substrate, employing a fully transparent structure with a light transmittance of ≥75%, without affecting the screen display effect.

[0060] The transparent conductive bottom electrode layer serves as both the bottom electrode layer of the piezoelectric tactile actuator and the conductive layer of the electrostatic actuator.

[0061] The piezoelectric actuator functional layer and the transparent conductive bottom electrode layer constitute a piezoelectric tactile actuator.

[0062] A capacitive touchscreen and a touchscreen driver module are included. The capacitive touchscreen is used to detect the sliding position of a user's finger on the screen in real time. When a finger touches the screen, the change in capacitance is collected by the touchscreen control module and uploaded to the main controller via an I²C or USB interface. The main controller sends driving parameters to the lower-level MCU based on the preset friction coefficient corresponding to the current finger position.

[0063] The tactile actuator driving module includes: Buck converter circuit: Provides a stable low-voltage power supply to the main controller and MCU; Boost circuit: Converts low-voltage DC to high-voltage DC (up to 150V) for high-voltage drive of electrostatic actuators or piezoelectric actuators; H-bridge circuit: Converts high-voltage DC into high-frequency AC signal (frequency ≥ 25 kHz, peak voltage up to 120V) and applies it to the piezoelectric actuator; The lower-level MCU receives instructions from the main controller, generates PWM signals with corresponding frequency, amplitude, and waveform, and controls the output of the boost and H-bridge circuits.

[0064] like Figure 5 As shown, the prototype's workflow is as follows: ① When a user slides their finger across the screen, the capacitive touchscreen collects location information in real time; ②The main controller queries the preset friction coefficient mapping table based on the location information to determine the target friction coefficient required for the current area; ③ The main controller selects the working mode (Mode 1: ultrasonic lubrication, reducing friction; Mode 2: electrostatic stagnation, increasing friction) and sends the drive parameters to the lower-level computer; ④ The lower-level computer generates a corresponding PWM signal to drive the boost and H-bridge circuits, and outputs a high-voltage, high-frequency signal to the tactile actuator; ⑤ The piezoelectric actuator or electrostatic actuator responds to the drive signal and adjusts the sliding friction between the finger and the screen; ⑥ The system monitors the tactile effect in real time through a closed-loop feedback mechanism (such as pressure sensing or capacitance change) and dynamically adjusts the driving parameters to achieve stable tactile reproduction.

[0065] In Mode 1 (piezoelectric actuator, ultrasonic lubrication), the drive signal is a high-frequency AC voltage (25 kHz-100 kHz, peak voltage 20V-120V), which can be a sine wave, square wave, or amplitude-modulated waveform. The amplitude modulation frequency is 0-100 Hz. The vibration modes of the glass are as follows: Figure 6 As shown, the vibration mode is Lamb standing wave A0 mode.

[0066] In Mode 2 (electrostatic actuator, electrostatic hysteresis), the driving signal is an AC voltage (50-200 V), applied between the transparent bottom electrode and the front of the glass, suitable for screens with a glass thickness of less than 0.5 mm. It is suitable for interactive scenarios requiring increased resistance, such as virtual buttons and sliders.

[0067] The prototype supports real-time rendering of various virtual haptic effects, including but not limited to: Virtual knob: Simulates the resistance felt when rotating a knob; Virtual slider: The friction force is gradually adjusted along the sliding path area to simulate the change in sliding damping; Virtual texture: In mode 1, the piezoelectric drive signal is modulated in amplitude or frequency to simulate the tactile feel of periodic texture.

[0068] Figure 7 The study demonstrates the periodic changes in friction force under mode 2, with a square wave drive signal, an amplitude modulation frequency of 1 Hz, and mode 2. Sliding friction force can be reduced by up to 75%.

[0069] Figure 8 The study demonstrates the periodic changes in friction force under a sinusoidal drive signal, an amplitude modulation frequency of 1 Hz, and mode 2. Sliding friction force can be reduced by up to 50%.

[0070] In summary, this prototype successfully achieved dual-mode friction control based on a fully transparent tactile actuator, is compatible with both ultrasonic lubrication and electrostatic hysteresis technologies, has a wide range of friction adjustment capabilities, and is suitable for next-generation integrated tactile interactive display screens.

[0071] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fully transparent tactile actuator, characterized in that: It includes a glass substrate (7), an adhesive layer (6), a transparent conductive bottom electrode (5), a seed crystal layer (4), a piezoelectric thin film layer (3), and a transparent conductive top electrode (2) arranged in sequence.

2. The fully transparent tactile actuator according to claim 1, characterized in that: The transparent conductive top electrode (2), the piezoelectric thin film layer (3), and the transparent conductive bottom electrode (5) together constitute a piezoelectric tactile actuator, and the transparent conductive bottom electrode (5) and the glass substrate (7) together constitute an electrostatic actuator.

3. The fully transparent tactile actuator according to claim 2, characterized in that: The glass substrate (7) is alkali-free aluminoborosilicate glass with a thickness of 0.3 to 0.5 mm; The transparent conductive bottom electrode (5) is made of fluorine-doped tin oxide, bismuth-doped tin oxide, or tin-doped indium oxide, with a conductivity greater than 3000 S·cm. - ¹.

4. The fully transparent tactile actuator according to claim 2, characterized in that: The adhesive layer (6) is made of hafnium oxide, titanium dioxide, aluminum oxide or magnesium oxide, and has a thickness of 10-20 nm. The seed crystal layer (4) is a lead titanate thin film with a thickness of 10-20 nm; The piezoelectric thin film layer (3) is made of lanthanum-doped lead zirconate titanate, with a thickness of 1-2 μm and a piezoelectric coefficient e. 31,f Greater than or equal to 8 C·m -2 The lanthanum doping concentration in PLZT is 0.5–2 mol%; The transparent conductive top electrode (2) is made of fluorine-doped tin oxide, tin-doped indium oxide, or gallium-doped zinc oxide, with a conductivity greater than 3000 S·cm. - ¹.

5. A method for manufacturing a fully transparent tactile actuator, characterized in that: The method for manufacturing the fully transparent tactile actuator according to any one of claims 1-4 includes the following steps: Provide a glass substrate (7); An adhesion layer (6) is deposited on the glass substrate (7); A transparent conductive bottom electrode (5) is deposited on the adhesion layer (6); A seed crystal layer (4) is deposited on the transparent conductive bottom electrode (5); A piezoelectric thin film layer (3) is deposited on the seed crystal layer (4); A transparent conductive top electrode (2) is deposited on the piezoelectric thin film layer (3).

6. The method for manufacturing a fully transparent tactile actuator according to claim 5, characterized in that: The adhesion layer was deposited by atomic layer deposition and annealed at 600–800°C. The transparent conductive bottom electrode (5) and the transparent conductive top electrode (2) are deposited by magnetron sputtering and annealed at 600°C in an oxygen atmosphere; The seed crystal layer (4) and the piezoelectric thin film layer (3) are deposited by sol-gel method and subjected to multi-stage heating and annealing treatment.

7. An interactive screen prototype, characterized in that: The fully transparent haptic actuator according to any one of claims 1-4 includes: The touchscreen module includes: a screen and a sensing signal processing circuit for detecting external signals; The host computer is used to receive external signals and generate drive parameters; The driving module includes: a lower-level machine, a boost circuit, and an H-bridge circuit, used to generate driving signals according to driving parameters and apply them to the fully transparent tactile actuator; The driver module also includes a step-down circuit to provide low-voltage power to the host computer and MCU.

8. The interactive screen prototype according to claim 7, characterized in that: The prototype also includes a pressure sensing module for detecting external pressure and forming a closed-loop feedback. The boost circuit is a type of boost circuit used to convert low-voltage DC to high-voltage DC up to 200V; the H-bridge circuit is used to convert high-voltage DC to high-frequency AC signals.

9. A driving method for an interactive screen prototype, characterized in that: Based on the interactive screen prototype of claim 7 or 8, the following steps are included: The touchscreen detects the position of a finger sliding on the screen. The main controller determines the target friction coefficient for the current area based on a preset friction coefficient mapping table; The main controller selects the working mode: mode one is ultrasonic lubrication mode, and mode two is electrostatic stagnation mode; the fully transparent tactile actuator can be used as both a piezoelectric tactile actuator and an electrostatic tactile actuator. The main controller sends drive parameters to the lower-level MCU; The MCU generates a PWM signal to drive the boost circuit and H-bridge circuit, and outputs a drive signal to the fully transparent haptic actuator. Piezoelectric or electrostatic actuators respond to drive signals and adjust the sliding friction between the finger and the screen.

10. The driving method for the interactive screen prototype according to claim 9, characterized in that: In mode one, the driving signal is a high-frequency AC voltage with a frequency of 25 kHz to 100 kHz and a peak voltage of 20 V to 120 V, and the waveform is a sine wave, square wave, or amplitude-modulated wave. In mode two, the driving signal is an AC voltage of 50 V to 200 V, applied between the transparent conductive bottom electrode and the front side of the glass substrate, and the thickness of the glass substrate is no more than 0.5 mm.

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