Designing and implementing an infrared touch panel based on pattern recognition

Master's Thesis of Computer Engineering (Artificial Intelligence)

Abstract

Design and implementation of an infrared touch panel based on

pattern recognition

The issue of positioning has always been controversial as the basis of issues raised in all types of touch screens, the meaning of positioning is to recognize the location of the finger or fingers placed on the surface of the touch screen. Touch due to the material used in their construction has caused a huge challenge in the way of making touch screens to increase the accuracy of positioning. In this thesis, first by examining the common touch screens, a new method for positioning regardless of the material used in the touch screen is presented. This method is a combination of Liu's [1] signal analysis method in acoustic touch panels [2] and touch panels made of infrared sensors provided by Moeller [3]. The most important difference between the presented method and the previous methods, in addition to the provided hardware, is the way of data analysis and the change in data modeling using the nearest neighbor method [4]. The results show the improvement of the performance of this method compared to Liu's method presented in the new platform.

Also, the use of this technology has become widespread in such a way that most of the industrialized countries of the world have a special desire to use it in their various products, for example, during the surveys conducted by the American DisplaySearch Institute in 2010, the most use of touch screens was in Japanese and American products. (Figure 1-2 shows this issue.) [2]. This, in the surveys conducted by the same institute in 2011, it is predicted that the amount of purchase of this product will increase by 105% by 2014. (more than twice compared to 2011) which shows the importance of this technology. (Figure 1-3) [3].

1-2- Classification of touch screens

Since the emergence of this technology, various types of touch screens have been produced and presented, and with the passage of almost three decades since the first model of this technology was made and presented, the issues raised in this field are still attractive and of interest to researchers in various sciences. Due to the wide range of manufacturers and the diversity of research in this field, various classifications have been presented so far for different types of touch screens, the most famous of which are: a) Wigdor classification This type of classification is based on the received data and how to process the desired touch screen as shown in Figure 1-5 [47]. b) Walker classification This classification is based on the type of platform, the degree of transparency Screen etc. is divided Figure 1-4 shows this type of classification [40].

     c) Classification of the American Institute of Display Search [1]

In this type of classification, the criteria is the type of sensors and the manufacturing technology of each of the touch screens which is drawn as a diagram in Figure 1-6[46].

Presenting a new classification

As mentioned, each of these categories It is provided for a specific purpose and by a specific person or institution. Since the topic studied in this treatise is about the issue of positioning - detecting the location of the finger or fingers placed on the surface of the touch screen - in touch screens, therefore this issue is not fully mentioned in any of the above categories and it cannot be included in these categories, so here a new category is presented which is a combination of the above categories and covers the issues raised in this treatise as well, which is presented as follows:

Here the screen performance criteria show, as mentioned, many companies and organizations have been active in the field of touch screens and each of them have adopted their own policy to solve the positioning problem, which can be included in two categories, which are: Exact base: in some researches, hardware methods have been used to increase the accuracy and speed of positioning. Methods such as: increasing the number of sensors, the location and placement of sensors, changing the size and miniaturization of sensors, etc.

Approximation base: in this category modeling, signal analysis and data processing are used instead of hardware methods.Touch Sensing Technology Approximation base wave

Image processing

Diffuse Illumination

Inverted FTIR

FTIR

Light Plane

Touchscreens can also be divided into two different categories in terms of the body [2], the overall classification as shown in Figure 7-1 is assumed:

In this new dissertation, the goal is to create a category It is one of the touch screens that combines the methods presented in the Acoustic wave type screens from the Approximation base touch screen category and the Infrared type screens from the Exact base category in such a way that the designed infrared type substrate is selected and the signal analysis methods provided in Aciustic type are applied on the data taken from this substrate. The main goal of this method is to provide a solution to reduce costs and reduce the hardware dependence of infrared touch screens. In this case, a new sub-group named Infrared wave is introduced in the proposed classification method.

1-3- A brief history of the development and innovation of existing touch technologies:

For the first time, in 1965, Johnson spoke about a simple structure that was the basis of capacitive touch screens [8], after that his detailed article in 1967, which was a theory about a new technology called touch screens [9] was published. Then, for the first time in 1968, an article was published that used this technology in air traffic control [10,11]. After that, the first capacitive touch screens were made by Benck at the WERN Institute in the early 1970s and used in 1973 [12].  Then, while working as a professor at the University of Kentucky Research Institute, Hurst invented the first resistive touch sensor called the Elograph, which allowed him to enter content faster. Elographics company was born next to this invention, this device was not similar to today's sensors; But this achievement was a big step towards new touch screens. Three years later, in 1974, Hurst designed the first transparent touch screen, and in 1977 he invented the Elograph and patented the resistive 5-Wire technical method, which is still the most widely used method. This technology was produced and used industrially in 1982 [13]. After that, from 1986 onwards, efforts were made to expand its use in various devices, in these years, the first graphical touch screen was presented, in the early 1990s, the first academic research was conducted by Sears [14], and in the late 1990s and early 2000s, the use of this type of touch screens in computer games became very prosperous, and until 2004, this accounted for the largest consumer market, but then From the presentation of touch screens by Nitendo and its reception, the use of touch screens has been greatly expanded and extended to personal computers [15]. Since the beginning of 2000, various and more complex types of touch screens have been provided, which we will examine in detail below. The sensors used in it are divided into several categories such as resistive, acoustic, capacitive, infrared, image, signal and sound. Since there have been many changes in this field since the mid-1960s, and a detailed description of each of them is not possible in this treatise, therefore, we will limit ourselves to a brief overview of each of them in just a few lines, which are:

-

-

-Sine wave output sensor capacitor

-Infrared[3]

- Background lights

-Piezoelectric transducer

-Signal

1-5- Conclusion and description of the general process of the dissertation

As stated, in the past years, extensive research has been done in the field of developing and using different types of touch screens. So that even in some sources, studies have been done on how to design the graphic interface of software related to touch screens, or the best way to define user protocols in different types of touch screens, or their use in moving vehicles [25-26].