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Acoustic pulse recognition enters touch-screen market
Abstract
Acoustic pulse recognition (APR) is an acoustic fingerprinting technique that is a new approach for bending-wave touch-screen signal processing, to locate the impact of touch screen and a better use of signal complexity. APR demonstrates the ability to process signals from brief impacts of styli and pulses existing in the form of continuous stream of acoustic noise from a finger sliding across the touch-screen surface. The principle operations of APRs are most suitable for surface-wave touch screen production lines. The random locations of the piezo increases the complexity and uniqueness of the acoustic fingerprinting of a touch at any given location. The 4-MB memory that contains acoustic fingerprints is a new approach to APR bending-wave technology. APR represents the bending-wave touch-screen technology and allows bending-wave to become a standard technology for touch screens.
... Therefore, in recent years, the Lamb wave touchscreen (LWT) has been developed to overcome the deficiency of SAW touchscreen. The LWT works in passive [5][6][7][8][9][10][11][12] and active modes [3,[13][14][15][16][17][18][19][20][21][22][23][24]. In the former mode, the Lamb wave is generated by the touch action and received by the piezoelectric wafer attached to the edge of the plate. ...
... The response signals of touch (referred to as acoustic fingerprints) at all the pixels are recorded as a database. The acoustic fingerprints with prior knowledge on their touch positions are directly used as the reference signal database [3,[9][10][11][12][13][14][15][16][17][18][20][21][22] or used to establish a locating model with neural network [24]. To achieve accurate localization of the unknown touch with the responded Lamb waves, various types of methods such as amplitude disturbed diffraction pattern [14][15][16], contact impedance mapping method [3,18], and learning method [20][21][22] have been explored. ...
Previous studies on Lamb wave touchscreen (LWT) were carried out based on the assumption that the unknown touch had the consistent parameters with acoustic fingerprints in the reference database. The adaptability of LWT to the variations in touch force and touch area was investigated in this study for the first time. The automatic collection of the databases of acoustic fingerprints was realized with an experimental prototype of LWT employing three pairs of transmitter–receivers. The self-adaptive updated weight coefficient of the used transmitter–receiver pairs was employed to successfully improve the accuracy of the localization model established based on a learning method. The performance of the improved method in locating single- and two-touch actions with the reference database of different parameters was carefully evaluated. The robustness of the LWT to the variation of the touch force varied with the touch area. Moreover, it was feasible to locate touch actions of large area with reference databases of small touch areas as long as the unknown touch and the reference databases met the condition of equivalent averaged stress.
... It can also detect some input tools of soft materials to absorb waves and the sensing performance is sensitive to contaminants on the screen. The another one is a bending wave scheme, where the sound wave caused by tapping on the screen is used as the sound source as well as the touch signal [88,89,89,90]. There are two methods of acoustic pulse recognition (APR) and dispersive signal technology (DST) [180]. ...
Touchscreens have been studied and developed for a long time to provide user-friendly and intuitive interfaces on displays. This paper describes the touchscreen technologies in four categories of resistive, capacitive, acoustic wave, and optical methods. Then, it addresses the main studies of SNR improvement and stylus support on the capacitive touchscreens that have been widely adopted in most consumer electronics such as smartphones, tablet PCs, and notebook PCs. In addition, the machine learning approaches for capacitive touchscreens are explained in four applications of user identification/authentication, gesture detection, accuracy improvement, and input discrimination.
... Touchscreen interactive devices have attracted developing concern in recent decades due to an increasing demand for computer, communication, and consumer electronics [1]. Touchscreens work on various operating principles, including resistive [2], capacitive [3], infrared [4], optical imaging [5], strain gauge [6], Surface Acoustic Wave (SAW) [7], and Acoustic Pulse Recognition (APR) [8]. Among these various techniques, SAW and APR use a simple piezoelectric method to transfer or detect signals, and thus have a broad range of applications owing to their lower cost, superior optical performance, higher durability, and easier integration [9]. ...
... Capacitive touch screen shows depend on the electrical properties of the human body to identify when and where on a show the client touching. See figure (2). As a result of this capacitive presentations can be controlled with light touches of a finger, for the most part they can't be utilized with a mechanical stylus or a gloved hand. ...
... They work based on conductivity of the touch object, so any nonconductive object cannot be sensed [1]. The main stream ultrasound touch technologies are surface-acoustic waves (SAWs) [2], acoustic pulse recognition (APR) [1], [3], and dispersive signal technology (DST) [1]. The main advantages they offer are simplicity in hardware and low manufacturing cost. ...
Touchscreen sensors are widely used in many devices such as smart phones, tablets, laptops, etc., with diverse applications. We present the design, analysis, and implementation of an ultrasonic touchscreen system that utilizes interaction of transient Lamb waves with objects in contact with the screen. It attempts to improve on the existing ultrasound technologies, with the potential of addressing some of the weaknesses of the dominant technologies, such as the capacitive or resistive ones. Compared to the existing ultrasonic and acoustic modalities, among other advantages, it provides the capability of detecting several simultaneous touch points, and also a more robust performance. The localization algorithm, given the hardware design, can detect several touch points with a very limited number of measurements (one or two). This in turn can significantly reduce the manufacturing cost.
... In surface acoustic wave and acoustic pulse recognition interactivity schemes, the touch position is detected by acoustic waves [7], [8]. In the former, ultrasonic waves are transmitted and reflected in the X-and Y-directions. ...
Visual display of information is an obvious requirement in today's highly digital world, and constitutes a powerful means of conveying complex information. This stems from the ability of the human eye and brain to perceive and process vast quantities of data in parallel. The history of visualizing information can be traced to the ancient era, when our ancestors carved images on cave walls and monuments. Mosaic art form emerged in the 3rd millennium BC, using small pieces of glass, stone, or other materials in combination to display information. These pieces are similar to pixels in the modern electronic display. The electronic display has become the primary human-machine interface in most applications, ranging from mobile phones, tablets, laptops, and desktops to TVs, signage, and domestic electrical appliances, not to mention industrial and analytical equipment. In the meantime, user interaction with the display has progressed significantly. Through sophisticated hand gestures, the display has evolved to become a highly efficient information exchange device. While interactive displays are currently very popular in mobile electronic devices such as smartphones and tablets, the development of large-area, flexible electronics, offers great opportunities for interactive technologies on an even larger scale. Indeed technologies that were once considered science fiction are now becoming a reality; the transparent display and associated smart surface being a case in point. Examines the market for interactive displays as the next omnipresent technology.
... The asymmetry helps ensure that the signatures are as complex as possible; a high level of complexity helps differentiate the signatures. A controller processes the output of the four transducers to produce the signature of the current touch and then compares it with the stored samples in the lookup table; interpolation between samples is used to calculate the correct touch location [39]. ...
Displays have recently seen widespread use as interactive input devices, mainly due to the addition or integration of touch-sensing capability into displays. This chapter is intended to provide a definitive reference on the touch technologies used in interactive displays. The objective of the chapter is to provide the reader with a substantial understanding of the operation, capabilities, advantages, disadvantages, limitations, and applications of different types of touch technology.
... A controller processes the output of the four transducers to produce the "signature" of the current touch and then compares it with the stored samples in the lookup table; interpolation between samples is used to calculate the correct touch location. 34 The concept of APR was developed in the early 2000s by Tony Hardie-Bick, an individual inventor at SoundTouch Ltd., a small company in the UK. Elo TouchSystems acquired the assets of SoundTouch in 2004 or 2005. ...
Touchscreen interactive devices have become increasingly important in both consumer and commercial applications. This paper provides a broad overview of all touchscreen technologies in use today, organized into 13 categories with 38 variations. The 13 categories are projected capacitive, analog resistive, surface capacitive, surface acoustic wave, infrared, camera-based optical, liquid crystal display in-cell, bending wave, force sensing, planar scatter detection, vision-based, electromagnetic resonance, and combinations of technologies. The information provided on each touchscreen technology includes a little history, some basic theory of operation, the most common applications, the key advantages and disadvantages, a few current issues or trends, and the author's opinion of the future outlook for the technology. Because of its dominance, this paper begins with projected capacitive; more information is provided on this technology than on any of the other touch technologies that are discussed. This paper covers only technologies that operate by contact with a display screen; this excludes technologies such as 3D gesture recognition, touch on opaque devices such as interactive whiteboards, and proximity sensing. This is not a highly technical paper; it sacrifices depth of information on any one technology for breadth of information on multiple technologies.
Classification and regression employing a simple Deep Neural Network (DNN) are investigated to perform touch localization on a tactile surface using ultrasonic guided waves. A robotic finger first simulates the touch action and captures the data to train a model. The model is then validated with data from experiments conducted with human fingers. The localization root mean square errors (RMSE) in time and frequency domains are presented. The proposed method provides satisfactory localization results for most human–machine interactions, with a mean error of 0.47 cm and standard deviation of 0.18 cm and a computing time of 0.44 ms. The classification approach is also adapted to identify touches on an access control keypad layout, which leads to an accuracy of 97% with a computing time of 0.28 ms. These results demonstrate that DNN-based methods are a viable alternative to signal processing-based approaches for accurate and robust touch localization using ultrasonic guided waves.
In this paper, we propose a transmission method, analysis, and implementation of an ultrasound touchscreen system based on Lamb waves. The basic principle of this system is to use the signals reflected from the fingertip contact. The inverted phase transmission method, which alternately transmits two opposite phases of input signals, was proposed to improve the signal contrast of the reflected signal from the fingertip. Experimental validation of this system was demonstrated on a 40-inch glass plate (800 mm × 600 mm) containing eight pairs of sensors. For imaging and localization, a simple and common method is used: the delay and sum method for imaging and the center of mass for localization. Compared with existing ultrasound technology, the proposed system is implemented in a large panel without using the training or prepared database. The system also provides reliable contact detection, simplicity, and other advantages of the present acoustic techniques.
Touchscreen technology and devices that use that technology have become widely popular over the past few years. Even so, very small amount of people knows that there are different technologies implemented in those devices that they use in everyday life. Through this seminar, we would try to present the different solutions currently available on the market. Simultaneously, we will compare between those solutions, emphasizing on differences between those technologies, and making the differences between them more obvious and understandable. Later, we will give our opinions on market trends in the future, and our vision and conclusion about this topic.
In the context of increasing complexity of mobile applications, by not exploring the hands’ many degrees of freedom the touchscreen interaction can appear as limited. Current computer interfaces have begun to take gestures into consideration more and more to provide a better user experience. Given that most of the interaction we have with our environment is accomplished through our hands, hand gestures make an ideal candidate for human computer interaction input. In this paper we present a glove based interface to provide additional input data based on hand postures on top of multi-touch gestures in applications for smart mobile devices with touchscreens. We describe application opportunities for employing hand posture for mobile devices. Using hand postures as shortcuts simplifies interactions and interfaces.
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