Figure 2 - uploaded by Pichaya Tandayya
Content may be subject to copyright.
A piezoelectric Braille cell. 

A piezoelectric Braille cell. 

Source publication
Article
Full-text available
The objective of this research is to investigate dynamic responses of the piezoelectric Braille cell when it is subjected to both electrical signal and touching force. Physical behavior of the piezoelectric actuator inside the piezoelectric Braille cell is analyzed. The mathematical model of the piezoelectric Braille system is presented. Then, data...

Context in source publication

Context 1
... Braille display unit is a device that displays refreshable Braille characters for visually impaired people to read by touching. A Braille character consists of six or eight dots in a rectangular array 3  2 or 4  2 [1]. Height of the dot is controlled by a piezoelectric bimorph underneath. Electrical signals stimulate the piezoelectric bimorphs to bend up or down, consequently causing the dots to rise or fall, creating the Braille character. The piezoelectric Braille display unit is an electrical control system thus it can be connected to a computer, mobile phone or Braille note ( Figure 1) as an user interface for the visually impaired person to read electronic media, such as e-mails, SMS, recheck the typing words, or browse the web site. Refreshable Braille cell has been continuously developed for over decades. Begin the 80’s, solenoids were used as actuators to control movement of the Braille dots [2,3 ]. Later, in the 90’s, relay-control Braille cell has been proposed [4]. Meanwhile, piezoelectric Braille cell has also been proposed [5, 6] and continuously developed. At the present, the piezoelectric Braille cell is a common type of refreshable Braille cell and commercially available [7] because it is relatively light weight and small size. In addition, there are some other actuators that can be applied to control the Braille dot such as pneumatic [8, 9], piezoelectric polymer [10], shape memory alloy [11, 12, 13], ultrasonic motor [14, 15] and ER fluid [16], but most of them are not commercially available due to their limitations. The piezoelectric Braille cell has many advantages, i.e., compact size, light weight and direct-electrical control. In this research, physical behavior of the piezoelectric bimorph inside the piezoelectric Braille cell is analyzed. The mathematical model of the piezoelectric Braille system is presented. Then, survey data of visually impaired people using a Braille-note is reported as design information and a reference input for calculation of the piezoelectric Braille response under the touching force. Based on the mathematical model, results are time response of the system, displacement response of the Braille dot at various applied voltages and touching force responses. The result provides understanding of the piezoelectric Braille cell behavior under both touching force and electrical excitation simultaneously. This is the important issue for development of piezoelectric Braille cell in senses of controlling Braille dot displacement or force-feedback in the future. A piezoelectric Braille display unit consists of a row of piezoelectric Braille cells. In this study, A Braille cell consists of eight dots in a rectangular array 4  2. Each dot is controlled by a underneath piezoelectric bimorph as illustrated in Figure ...

Similar publications

Article
Full-text available
A parametric study was performed to design a device capable of treating small targeted regions within the prostate using high intensity focused ultrasound, while sparing the surrounding organs and minimizing the number of elements. The optimal focal length (L), operating frequency (f), element size (a) and central opening radius for lodging an imag...
Article
Full-text available
A sensing system for fractional exhaled nitric oxide (FeNO) measurement is presented, which is characterized by a compact setup and a cost potential to be made available for the patient at home. The sensing is based on the work function measurement of a phthalocyanine-type sensing material, which is shown to be sufficiently sensitive for NO(2) in t...
Article
Full-text available
When capacitive micromachined ultrasonic transducers (CMUTs) are monolithically integrated with custom-designed low-noise electronics, the output noise of the system can be dominated by the CMUT thermal-mechanical noise both in air and in immersion even for devices with low capacitance. Because the thermal-mechanical noise can be related to the ele...
Article
Full-text available
The achievement of high sensitivity and highly integrated transducers is one of the main challenges in the development of high-throughput biosensors. The aim of this study is to improve the final sensitivity of an opto-mechanical device to be used as a reliable biosensor. We report the analysis of the mechanical and optical properties of optical wa...
Article
Full-text available
This paper presents a simple and costs effective equipment design multi-feeder data logger for recording and monitoring power quality. The system design uses remote supervising and multi-feeder data logging system (RESMOS). The data collected through resmos portable unit (RMPU) will automatically be saved with the format as binary and comma separat...

Citations

... After understanding the piezoelectric bimorph characteristics, this section utilizes the findings from Sections 2 and 3 regarding power generation from various inputs parameters to explore energy harvesting from actual movement. The finger movement when clicking was inspired by [30]; therefore, the computer mouse was selected for this study because of the frequency and rapidity of the mouse clicking movement. The first prototype underwent testing to assess the power output relative to the input, following a similar approach as in Section 3. Finally, the results were examined, and potential future directions are discussed. ...
Article
Full-text available
Electrical devices are integral to daily life, but limited battery life remains a significant issue. A proposed solution is to convert dissipated energy from human motion into electricity using piezoelectric materials. This study investigates lead–zirconate–titanate (PZT) piezoelectric materials in bimorph configuration, conducts performance tests to understand their characteristics and determine the optimal load resistance, and develops an energy-harvesting prototype. Performance tests adjusted input parameters and varied load resistance and input magnitude to optimize power gained from the PZT bimorph. A suitable human movement for the application of the bimorph is a mouse-clicking motion by fingers. A prototype was created by integrating the bimorph into a computer mouse to capture energy from clicks. The results showed that the deformation rate of the PZTs, input magnitude, and resistance load were key factors in optimization. The bimorph configuration produced 0.34 mW of power and 5.5 V at an optimum load of 5072 Ω, requiring less effort to generate electricity. For the computer mouse energy harvester case, it yielded a total average power of approximately 38.4 μW per click with a click frequency of 4 Hz. This power could be used to support IoT devices such as human sensors (e.g., CO2, temperature, and pulse sensors) and smart home sensors, enabling comprehensive health and environmental monitoring. In conclusion, input specifications, magnitude, and load resistance are essential for optimizing piezoelectric energy harvesters.
... The low cost, compact size, and large displacement of piezoelectric bender actuators is well suited to applications such as buzzers in alarm devices, braille heads [1], needle actuators for knitting machines [2], fiber optic switches [3], positioning of hard drive heads [4], pneumatic proportional control valves [5], and cantilever detectors in atomic force microscopy (AFM) [6]. ...
Article
Piezoelectric benders are widely used in industrial applications due to their low-cost and compact size. However, due to the large relative size and cost of displacement sensors, bender actuators are often operated in open-loop or with feed-forward control, which can limit positioning accuracy to 20% of full-scale. To improve the positioning accuracy of piezoelectric benders, this article proposes integrating resistive strain gauges into the electrode surface by chemical etching or laser ablation. These strain sensors are then used to measure and control the tip displacement. The proposed sensors are shown to suffer from significant cross-coupling between the actuator voltage and measured signal; however, this can be mitigated by judicious choice of the sensor location and actuator driving scheme. In addition to position sensing, a method is also presented for simultaneous estimation of the contact force between the actuator tip and load. The proposed methods are validated experimentally by controlling the tip position of a piezoelectric bender while simultaneously estimating the force applied to a reference load cell.
... Their peak blocked force is 0.28kg at 50ºC and 0.23kg force at room temperature after cooling. This blocked force at room temperature is sufficient so that the pixels are perceivable while reading [3]. The nominal rate of cooling at room temperature is 3.61ºC/s and when the temperature of the pixels drops to 38ºC, they can be manually reconfigured back to their flat state by applying a compressive force for repeatable actuation. ...
... One ubiquitous application for piezoelectric benders are buzzers in alarm devices, and timers. However, benders also find applications in more exotic applications such as braille heads [1]. A large application often overlooked are warp knitting machines that dominate the world's clothing fabric industry. ...
Article
This article derives design guidelines for integrating strain gauges into the electrodes of piezoelectric bending actuators. The proposed sensor can estimate the actuator tip displacement in response to an applied voltage and an external applied tip force. The actuator load force is also estimated with an accuracy of 8% full scale by approximating the actuator response with a linear model. The applications of this work include micro-grippers and pneumatic valves, which both require the measurement of deflection and load force. At present, this is achieved by external sensors. However, this work shows that these functions can be integrated into the actuator electrodes.
... This mechanical deformation is used to raise the pins up and down to form Braille characters. Actually it is very fast but when used for multi line Braille display it becomes bulky and too costly (11) . ...
... Another possibility is to use piezoelectric bimorphs. These devices can easily produce vibrations in the hundreds of Hz, but typically cannot produce deflections larger than a fraction of a millimeter unless they are long (≈4 cm), which again imposes a packaging challenge [7], [8]. ...
Article
We present a lightweight, low power, and compliant miniature dielectric fluid transducer intended for haptic surface display. The actuator has a large strain and fast response without an external compressor. It consists of a thin oil-filled pouch with a 1.5 mm diameter opening covered with a silicone membrane. The application of voltage causes the pouch to squeeze the oil and form a bump by stretching the silicone membrane. The actuator produces 1.45 mm bump height at 3 kV and 13 mN at 3.5 kV using \approx 10μ\text{10}\,\mu l of oil. The power consumption is << 3 mW. Though the largest bump height has a bandwidth near 5 Hz, the device achieves perceivable vibration at 200 Hz with a bump height of 200 μ\mu m. The actuators can be packed closely and controlled individually to create dynamic texture displays, suitable for active surface exploration with the fingertips. The simulation results show the width of the actuator can be reduced without affecting the performance. Tests with human subjects show that users differentiated simple bump patterns with a 98.8% success rate.
... Recent advances have provided braille users with refreshable braille displays that enable users to reuse the braille system as different reading materials. A "Tactobook" by Velázquez, for example, demonstrates the capability of a piezoelectric tactile terminal for braille readers by translating electronic books to braille code and reproduce them in portable electronic braille terminal using the piezoelectric braille cells [13,14]. ...
Article
Full-text available
span style="font-size: 9pt; font-family: 'Times New Roman', serif;">Among the major issues faced by the visually impaired people is the inability to read, and this is could be addressed by learning braille. However the scarcity of skilled instructors to teach the braille codes to the visually impaired people limits the learning process. This paper presents a psychophysical study on the ability of people with visual challenges to identify hijaiyah letters from a specially developed Arabic braille module. This module consists of six miniature solenoids that are wirelessly controlled via a Bluetooth and an Arduino Uno microcontroller. Five different hijaiyah letters were provided to the participants and were randomly repeated for three times. The participants were required to touch the Arabic braille module and state the hijaiyah letters that were displayed. With priori knowledge and initial familiarization of the braille patterns, 72.9% of the trials showed accuracy between the braille display and the stated hijaiyah letters. 20% of the participants have the highest repeatability responses of 80%. The outcome of this work showed the optimistic capability of the wirelessly controlled Arabic braille display to assist visually impaired individual to read hijaiyah braille letters and ultimately promotes independence in learning. </span
... This mechanical deformation is used to raise the pins up and down to form Braille characters. Actually it is very fast but when used for multi line Braille display it becomes bulky and too costly (11) . ...
Article
Background/Objectives: The aim of this study was to implement the rotating cubes for designing the Braillerefreshable display. The rotating cube Braille display has many benefits i.e., compact size, low cost etc. Methods/Statistical analysis: refreshable Braille display is an electro mechanical device which forms Braille charactersby raising pins through holes on flat surface. The raising of such pins is accomplished by complex and costly systems like solenoids or piezo-electric crystals or EAP (Electro Active Polimer). We developed the prototype of e-book reader, which is a low cost electro mechanical system aimed at assisting visually impaired to access the e-books. Findings: Many design concepts were proposed earlier and prototypes were built, and were tested successfully in thepast by using three simple rotating cubes. The main parameters like dot spacing, overall dimension, touching force and operating voltage obtained are discussed. Dot spacing 2.5 [mm] with reference to International standard has been maintained. Regarding overall dimension, the display unit is designed to have dimension of 120mm width to 150mm height adhering to NLS standard of Braille dot spacing, and the tactile surface will feature 13 lines with 14 characters per line. The touching force of 0.32N and operating voltage below 25 V was obtained and used. Novelty/Applications: The Solenoid is used for positioning the faces of individual cubes, which can be arranged in different positions thereby forming all Braille characters. The high power consumption which remained the major head ache in solenoid electromagnetic actuator models was a major challenge we faced initially, which we overcame with our unique innovative design combining cubes that can rotate to form Braille dots and electromagnetic actuator which can be positioned at various places to run this cubes. So Keeping Occam's Razor Principle in mind, we went ahead to design a multicell/multi-line electronic refreshable Braille display as a technology demonstrator by using three simple rotating cubes.
... A finger contacts the interface parts, and tactile sensation is generated by pins. The pins must be placed in high density, and CFRP(Carbon Fiber Reinforced Plastics) is used as similar to Smithmaitrie's research [29]. The interface parts are fabricated by 3D printing (we used ABS resin). ...
Conference Paper
Full-text available
In this study, we considered a tactile and force fusion display. Tactile device was composed of an interface part fabricated by 3D printing, pins, and cantilever-type actuators. The device was compact and had the ability to stimulate the mechanoreceptors of the fingertips. Therefore, we propose using microelectronic mechanical-system (MEMS) technology to reduce device size. And force display is multi-finger haptic types. It has a large working area based on the Spidar haptic system. Another characteristic is that the contact location can be changed. This display could stimulate within the double-point threshold of the fingertips and generate multi-finger haptics. CCS CONCEPTS • Hardware • Human-computer interaction
... Although bending is limited with respect to the aspect ratio of the bimorph, it is possible to achieve displacement of the height of a Braille dot with actuators of a few centimeters length. The study presented in [5] and [4] reports an investigation of a classic piezo based Braille actuator with respect to length of the bimorph, supply voltage, displacement of the pin and blocking force. In particular, bimorph in the 25-35mm length range achieve displacement of 0.4 mm of the dot, at 0.1 N blocking force. ...
Conference Paper
Full-text available
This works presents a survey on recent technologies applied for Refreshable Braille Displays (RBD): these devices allow the dynamic rendering of refreshable Braille characters, analogously to a computer monitor rendering text and other visual information. Although commercially available RBD share a similar technology based on piezo actuators, and feature a single line of characters at a relatively high cost, alternative solutions have been proposed in recent years. They include adaptation of existing actuators and technologies to the rendering of Braille, and innovative materials used for developing actuators appositely designed for RBDs. In this survey, we compare performance of the above methods analyzing potential benefits and limitations of the different technologies.