The Reverse Re Engineering of Capacitive Touch Screen System

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 3, March 2012)

The Reverse Re Engineering of Capacitive Touch

Screen System

Vinit tarey

1

, Kaushal Bhatt

2

, Pradeep Rupayla

3

1,2,3_{Vinit Tarey, MITS, Datana Ujjain MadhyaPradesh India}

1

[email protected]

2_{[email protected]} 3_{[email protected]}

Abstract—According to advancement of the touch screen mobile and tablet pc technology the batteries playing an important role for driving the mobile phone and tablet pc. Battery backup is a big issue for all android phones, smart phones and tablet pc, in this research paper we have present an automated battery charging system which uses reverse re engineering of capacitive touch screen which will reduce the problem of battery backup. This advance system uses battery charging by the variation between two membrane which generate capacitance and by this variation the EMF is induced or charge is generated which is used to charge the various levels of lithium cell present in the mobile battery. These capacitive membranes that are made up of piezoelectric crystal are so much sensitive so that the variation between capacitive membranes is possible even by air or small press. This advance charging system contains some methodology of charging the battery that will be explained in this research paper.

Keywords—Capacitive Membrane, Piezoelectricity, Nanotechnology, Power rating, Nano cells, reverse reengineering.

I. INTRODUCTION

The innovation in the technology of the communication devices like mobile phones and tablets containing the lithium cell based battery system and this battery system provides the power to the mobiles. Some special type of battery charger is been used to recharge the mobile phone batteries the battery charger uses ac input supply and dc output based on the full wave bridge rectifier technique.

Lithium Battery:-

The lithium battery contains a cathode and anode the positive and negative points on the lithium battery .A The lithium battery contains the various combinations of carbon liquid, manganese dioxide, lithium perclorate ,thionyl chloride and various combination of chemical is been used to construct the various power rating batteries. The battery is available between1.5volt to 3.7volt between 800ma to 2200ma current.[1]

A lithium-ion battery (sometimes Li-ion battery or LIB) is a family of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge, and back when charging. Chemistry, performance, cost, and safety characteristics vary across LIB types. Unlike lithium primary batteries (which are disposable), lithium-ion electrochemical cells use an intercalated lithium compound as the electrode material instead of metallic lithium. The charging and discharging of battery is shown in fig 1.

[image:1.612.324.565.494.690.2]

Depending on materials choices, the voltage, capacity, life, and safety of a lithium-ion battery can change dramatically. Recently, novel architectures using nanotechnology have been employed to improve performance. Pure lithium is very reactive. It reacts vigorously with water to form lithium hydroxide and hydrogen gas. Thus, a non-aqueous electrolyte is typically used, and a sealed container rigidly excludes water from the battery pack.

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International Journal of Emerging Technology and Advanced Engineering

Capacitive membrane:-

Capacitive membranes are widely used in various places like liquid level gauges, pressure meters accelerometer and high-precision petitioners [2] .In such applications the capacitive membranes is used as a capacitive sensors in which physical or mechanical quantities are converted into capacitance values, which are further processed by electronics circuit, But in some systems like in touch screen mobile phone the physical touch on mobile screen is will generate change in capacitance and this will further processed by the electronic circuit and variation in the membrane of touch screen will cause change in capacitance this change will use as some action. This phenomenon can reverse as variation in the capacitive membrane can be converting into voltage. This can be possible if we use the piezoelectric crystal as a material of capacitive membrane then it will generate a reverse EMF on each press and release on the touch screen.

Piezoelectric Crystal:

Certain single crystal materials exhibit the following phenomenon: when the crystal is mechanically strained, or when the crystal is deformed by the application of an external stress, electric charges appear on certain of the crystal surfaces; and when the direction of the strain reverses, the polarity of the electric charge is reversed. This is called the direct piezoelectric effect, and the crystals that exhibit it are classed as piezoelectric crystals [5].

II. TECHNOLOGY FOUNDATION

The Lithium batteries were first proposed by M.S. Whittingham, now at Binghamton University, while working for Exxon in the 1970s [1]. Whittingham used titanium sulfide as the cathode and lithium metal as the anode. The three primary functional components of a lithium-ion battery are the anode, cathode, and electrolyte. The anode of a conventional lithium-ion cell is made from carbon, the cathode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent.

Battery Types:-

The most commercially popular anode material is graphite. The cathode is generally one of three materials: a layered oxide (such as lithium cobalt oxide), a polyamine (such as lithium iron phosphate), or a spinel (such as lithium manganese oxide).

The electrolyte is typically a mixture of organic carbonates such as ethylene carbonate or diethyl carbonate containing complexes of lithium ions.

These aqueous electrolytes generally use non-coordinating anion salts such as lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate monohydrate (LiAsF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), and lithium triflate (LiCF3SO3).In the present world the lithium polymer batteries are widely used which contain Positive ,Negative electrode and one separator which conducting polymer electrolyte this battery mainly contains carbon lithium cobalt and oxides. By implementation of nanotechnology in the field of lithium battery development its performance can be further increases.

Capacitance:

In electromagnetism capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored (or separated) for a given electric potential. A common form of energy storage device is a parallel-plate capacitor or two parallel polymer membranes. In a parallel plate capacitor, capacitance is directly proportional to the surface area of the conductor plates and inversely proportional to the separation distance between the plates. If the charges on the plates are +q and −q, and V give the voltage between the plates, then the capacitance is given by C= q/v;

The energy stored in a capacitor is equal to the work done to charge it. Consider a capacitor of capacitance C, holding a charge +q on one plate and −q on the other. Moving a small element of charge dq from one plate to the other against the potential difference

V = q/C requires the work dW: dW=q/c dq

where W is the work measured in joules, q is the charge measured in coulombs and C is the capacitance, measured in farads.[3]

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International Journal of Emerging Technology and Advanced Engineering

III. SYSTEM MODEL ANDIMPLEMENTEDDESIGN

Figure shows the implemented design that will use for continually recharging of the lithium battery. In this system variation on the capacitive touch screen is responsible for variation in the capacitance that will given to the capacitance to voltage converter circuit ,this circuit will change capacitance into the voltage then this voltage is feed to a filter then to lithium battery .Here we are using special type of lithium batteries which is not constructed by a single lids of lithium and carbon whether it is constructed by using thousands of very small structures of lithium and carbon batteries these batteries are basically arrange in levels and because of its small structure it requires very much less voltage for charging ,so that continually charging can be achieved .

The main factors that are been used for this design are as follows:

Compatibility:- It is an most important factor because the battery we are using in the mobile system should provide a proper output voltage and current that will used to provide power to mobile systems .It should follow all specification that are defined in battery standards. The battery that we are using in our system is uses multiple small lithium carbon cells so that we can achieve compatibility as per defined requirements. This whole system should be compatible with the operating system like android and, JAVA based mobile.

Sensitivity: - The piezoelectric capacitive membrane that we are using in this circuit should be very much sensitive because as much variation in the capacitive membrane will vary the capacitance and applied force on to this piezoelectric membrane will also been vary charging speed of battery.

Automatic Cutoff: - The continuous charging may damage the battery because if the battery cells are completely charge then there may be chance of overheating or overcharging that may damage the battery and hazards can happen so that there is an automatic cutoff circuitry that will cut off the charging of mobile.

Quick Response:- The battery response should be quick it should start charging as it get the input from the charging circuit and also it should be quickly respond as per requirement and should also sensitive for the Capacitive membrane response.

Battery Manager:- Software assistance is very much necessary for completing the charging and discharging task of any mobile so that we are using a battery manager software in the android and java based mobile which are

basically control the process of the charging on each touch as shown in the code some changes has been made to achieve the proper operation at real time.

package com.android.server; [4]

/* "plugged" - int, 0 if the device is not plugged in; 1 if plugged into an AC power adapter; 2 if plugged in via USB; 3 if using touch screen for charging. */

Private static final int BATTERY_PLUGGED_NONE = 0; private boolean mAcOnline;

private boolean mUsbOnline; private Boolean mTouchOnline; private int mPlugType;

if (plugTypeSet == 0) { return false; }

int plugTypeBit = 0; if (mAcOnline) { plugTypeBit |=

BatteryManager.BATTERY_PLUGGED_AC; } if (mUsbOnline) {

plugTypeBit|=

BatteryManager.BATTERY_PLUGGED_USB; } if (mTouchOnline) {

plugTypeBit|=

BatteryManager.BATTERY_PLUGGED_TouchScreen;} return (plugTypeSet & plugTypeBit) != 0;

}

final int getPlugType() { return mPlugType; }

if (mAcOnline) { mPlugType=

BatteryManager.BATTERY_PLUGGED_AC; } else if (mUsbOnline) {

mPlugType=

BatteryManager.BATTERY_PLUGGED_USB; } else if (mTouchOnline) {

mPlugType=

BatteryManager.BATTERY_PLUGGED_Touch; } else {

mPlugType = BATTERY_PLUGGED_NONE;} mPlugType != mLastPlugType ||

synchronized (this) {

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International Journal of Emerging Technology and Advanced Engineering

Fig 2Data Flow Chart for Battery Charging System

Connection Strategy:-

The figure 3 shows the way of that has been used to charge the mobile battery, as the touch has been made on the piezoelectric capacitive membrane the variation in the capacitance is been there and due to the property of the piezoelectric material the charge is been generated in it, that charge is been feed to the capacitance to voltage converter circuit which will then convert it into voltage and then this voltage feed to the battery charging circuit. This circuit will start charging the various levels of battery as shown in figure .when the battery is get fully charged then it will cut off the system.

Fig 3 Battery Charging System Prototype

IV. REALIZATION

The system mainly includes capacitive piezoelectric touch screen membrane, Capacitance to voltage converter, Nano cells based lithium battery and battery manager.

[image:4.612.310.561.132.479.2]

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International Journal of Emerging Technology and Advanced Engineering

The resonant frequency of a quartz crystal oscillator is changed by mechanically loading it, and this principle is used for very accurate measurements of very small mass changes in the quartz crystal microbalance and in thin-film thickness monitors. Quartz crystals have piezoelectric properties: they develop an electric potential upon the application of mechanical stress. [5]

S.No. Piezoelectric Material Quantitative approximation[5]

Material Max. Input Voltage

(volts/mm)

Acoustic Power

(watts/cm3)

1 Quartz 10500 1000

2 Lithium

Niobate

1000 100

3 Navy Type I 470 450

4 Navy Type II 235 125

The MAX1044 and ICL7660 is monolithic [2], CMOS switched-capacitor voltage converters that invert, double, divide, or multiply a positive input voltage. They are pin compatible with the industry-standard ICL7660 and LTC1044. Operation is guaranteed from 1.5V to 10V with no external diode over the full temperature range. They deliver 10mA with a 0.5V output drop. The MAX1044 has a BOOST pin that raises the oscillator frequency above the audio band and reduces external capacitor size requirements. The MAX1044/ICL7660 combines low quiescent current and high efficiency. Oscillator control circuitry and four power MOSFET switches are included on-chip. Applications include generating a -5V supply from a +5V logic supply to power analog circuitry. For applications requiring more power, the MAX660 delivers up to 100mA with a voltage drop of less than 0.65V.

Super capacitor based hybrid battery sandwich with nickel/tin anode,

polyethylene

oxide (PEO) electrolyte and polyaniline cathode layers [7], it was built as proof that lithium ions would move efficiently through the anode to the electrolyte and then to the super capacitor like cathode, which stores the ions in bulk and gives the device the ability to charge and discharge quickly.

V. CONCLUSION

Touch Screen technology grows at rapid pace. Tomorrow seems to be Touch sensitive world. Considering this we use touch screen technology our major point of research. If we talk about any device a battery life of that device play major role and if we talk about touch sensitive devices a battery life of device must be more important. In our research we consider both touch and battery. We can charge battery of Touch sensitive device using capacitive variance that makes Touch sensitive devices to be in working condition. We charge battery by changing the variance of capacitive touch. The ideas of battery charging through touch are presented in our research paper and it’s useful in future implementation of charging through Touch Sensitivity along with AC plugged or USB Cable.

References

[1] Battery Types and Characteristics for HEV Thermo Analytics.

[2] ICL7660-MAX104 data sheet capacitance to voltage converter.

[3] Simon M. Sze, Kwok K. Ng (2006). Physics of Semiconductor Devices .

[4] Package code of android server for battery manager Developer.android.com

[5] Introduction to the piezoelectric Transducer Crystal.

[6] electronics-lab articles Li Ion reconstruct

[7] High-performance lithium battery anodes using silicon nanowires.