06-04-2011, 10:32 AM
Submitted by:
Abhishek Tewari
[attachment=11761]
INTRODUCTION
A touch screen is an input device that allows users to operate a PC by simply touching the display screen.
The touch screen has two main attributes.
First it lets you interact directly with what is displayed.
Second directly with STYLUS.
There are 3 types of touch screen technologies:
Resistive touch screen
Surface acoustic wave
Capacitive touch screen
TYPES
1. RESISTIVE TOUCH SCREEN
2. CAPACITIVE TOUCH SCREEN
3. SURFACE ACOUSTIC WAVE TOUCH SCREEN
RESISTIVE TOUCH SCREEN
1. A resistive touch screen panel is composed of several layers.
2. Two thin, electrically conductive layers separated by a narrow gap.
3. When pressure is applied two metallic layers become connected at that point: the panel then behaves as a pair of voltage dividers with connected outputs.
4. This causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing.
TYPES OF RESISTIVE TOUCH SCREENS
1. 4 WIRE RESITIVE
• Touch measurement in 4 Wire technology is a 2 step process.
• First the distance along the x axis at the point of touch is measured by creating a horizontal voltage gradient on the top sheet, with the bottom acting as the return layer.
• Second a vertical voltage gradient is created on the bottom layer, to measure the y axis.
DIFFERENT MODES FOR DETECTION
A touch-screen controller is simply an ADC that has built-in switches to control which electrodes are driven and which electrodes are used as the input to the ADC. The ADC can often be operated with different reference modes: single-ended or differential.
SINGLE ENDED CONFIGURATION
2. 5 WIRE RESISTIVE
In 5 Wire resistive, the main electronics are on the glass bottom layer. A uniform voltage is applied to the top plastic layer. A touch causes an electrical contact between the top and bottom layers. Depending on the point of touch the voltages at the 4 corners of the glass are different—these are measured, and used by a complex algorithm in the controller to calculate the x-y coordinate of the point of touch.
Resistive Touch Screen
Characters:
1. Cost effective solutions
2. Activated by a stylus, a finger or gloved hand
3. Not affected by dirt, dust, water, or light
4. 75%~85% clarify
5. Resistive layers can be damaged by a very sharp object.
Abhishek Tewari
[attachment=11761]
INTRODUCTION
A touch screen is an input device that allows users to operate a PC by simply touching the display screen.
The touch screen has two main attributes.
First it lets you interact directly with what is displayed.
Second directly with STYLUS.
There are 3 types of touch screen technologies:
Resistive touch screen
Surface acoustic wave
Capacitive touch screen
TYPES
1. RESISTIVE TOUCH SCREEN
2. CAPACITIVE TOUCH SCREEN
3. SURFACE ACOUSTIC WAVE TOUCH SCREEN
RESISTIVE TOUCH SCREEN
1. A resistive touch screen panel is composed of several layers.
2. Two thin, electrically conductive layers separated by a narrow gap.
3. When pressure is applied two metallic layers become connected at that point: the panel then behaves as a pair of voltage dividers with connected outputs.
4. This causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing.
TYPES OF RESISTIVE TOUCH SCREENS
1. 4 WIRE RESITIVE
• Touch measurement in 4 Wire technology is a 2 step process.
• First the distance along the x axis at the point of touch is measured by creating a horizontal voltage gradient on the top sheet, with the bottom acting as the return layer.
• Second a vertical voltage gradient is created on the bottom layer, to measure the y axis.
DIFFERENT MODES FOR DETECTION
A touch-screen controller is simply an ADC that has built-in switches to control which electrodes are driven and which electrodes are used as the input to the ADC. The ADC can often be operated with different reference modes: single-ended or differential.
SINGLE ENDED CONFIGURATION
2. 5 WIRE RESISTIVE
In 5 Wire resistive, the main electronics are on the glass bottom layer. A uniform voltage is applied to the top plastic layer. A touch causes an electrical contact between the top and bottom layers. Depending on the point of touch the voltages at the 4 corners of the glass are different—these are measured, and used by a complex algorithm in the controller to calculate the x-y coordinate of the point of touch.
Resistive Touch Screen
Characters:
1. Cost effective solutions
2. Activated by a stylus, a finger or gloved hand
3. Not affected by dirt, dust, water, or light
4. 75%~85% clarify
5. Resistive layers can be damaged by a very sharp object.
