Contemporary mobile phones are all touch screens, why can touch screens respond to human touch?

Because there is a metal substance on the screen that can conduct electricity, when the finger touches it, the capacitance here changes, and the touch screen reaction is completed.

When your finger comes into contact with a metal substance that conducts electricity in your phone, the capacitance of the screen changes. It also causes a change in the frequency of the oscillator connected to it. This creates the effect of a touch screen.

Most of the mobile phones we use now are capacitive touch screens, and capacitive touch screens have two layers of screens, which are divided into inner screens and outer screens, and the inner screen is the touch receiving screen.

It has a lot to do with the special settings of the screen.,It's completely set to be more sensitive to people or can be recognized.,When people touch it, they will naturally react.。

The types of touch screens mainly include resistive technology touch screens, surface acoustic wave technology touch screens, capacitive technology touch screens, etc., and their principles are not the same.

1. In addition to fingers, the touch screen of the mobile phone can also be replaced by a capacitive pen.

2. Because the capacitive pen is made of conductive materials, it has the characteristics of conductivity, and can be used to touch the capacitive screen to complete an auxiliary tool for operating the mobile phone screen. Therefore, in addition to fingers, the touch screen of the mobile phone can also be replaced by a capacitive pen.

3. Because the working principle of the capacitive pen is that the capacitive touch screen uses the current induction of the human body to work. It is a four-layer composite glass screen, the inner surface of the glass screen and the interlayer are each coated with a layer of ITO (i.e., coated conductive glass), and the outermost layer is a thin layer of silica glass protective layer. The ITO coating is used as the working surface, four electrodes are drawn from the four corners, and the inner ITO is the shielding layer to ensure a good working environment.

4. Therefore, in addition to fingers, the touch screen of the mobile phone can also be replaced by a capacitive pen.

The touch screen of a mobile phone, also known as the touch panel, is an inductive liquid crystal display device that can receive input signals such as contacts.

When the graphic buttons on the screen are touched, the haptic feedback system on the screen can drive various connection devices according to the pre-programmed program, which can be used to replace the mechanical button panel and create vivid audio and video effects through the Joyce Qin LCD screen.

In 1971, Dr. Samuel Hurst invented a touch sensor, which was the prototype of the touch screen. Three years later, he designed the first transparent touchscreen. In 1977, touchscreen technology was greatly improved, and it is still widely used and rapidly evolving today.

The touch screen is composed of a touch detection part and a touch screen controller; The touch detection component is installed in front of the display screen and is used to detect the user's touch position and accept the backward touch screen controller; The main function of the touch screen controller is to receive touch information from the touch point detection device, convert it into contact coordinates, and then send it to the CPU, which can also receive the commands sent by the CPU and execute them.

Mobile phone touch screen is divided into two kinds: resistive screen and capacitive screen, most of the popular touch screens are lens screens, that is, flat resistive and mirror capacitive screens, most of Nokia are resistive screens, and the representative of capacitive screens is iPhone.

Resistive touch screen, commonly known as "soft screen", is mostly used in mobile phones with Windows Mobile system;

Capacitive touch screen is commonly known as "hard screen", such as iPhone and G1 and other machines use this screen quality.

1 Basic Principles of Touch Screens.

The working part of a typical touch screen is generally composed of three parts, as shown in Figure 1: two transparent resistive conductor layers, an isolation layer between the two conductors, and electrodes. The resistive conductor layer is composed of resistive materials, such as indium tin oxide (ITO), which is coated on the substrate, the upper substrate is made of plastic, and the lower substrate is made of glass.

The insulating layer is a viscous insulating liquid material, such as polyester film. The electrode is composed of a material with excellent electrical conductivity (such as silver powder), and its conductivity is about 1000 times that of ITO.

When the touch screen is operating, the upper and lower conductor layers act as a resistive network, as shown in Figure 2. When a voltage is applied to a layer of electrodes, a voltage gradient is formed on that network. If there is an external force that causes the upper and lower layers to come into contact at a certain point, the voltage at the contact point can be measured in the other layer where the electrode is not pressed, so as to know the coordinates at the contact point.

For example, if the voltage is added to the electrode (x+,x) on the top layer, a voltage gradient is formed on the top conductor layer, and when there is an external force that makes the upper and lower layers contact at a certain point, the voltage at the contact point can be measured at the bottom layer, and then the x coordinate at the point is known according to the distance relationship between the voltage and the electrode (x+). Then, switch the voltage to the bottom electrode (y+,y) and measure the voltage at the contact point at the top layer to know the y coordinates.

2 Control implementation of touch screen.

Nowadays, in many PDA applications, the touch screen is used as an input device, and there are special chips for the control of the touch screen. Obviously, the control chip of the touch screen has to complete two things: one is to complete the switching of the electrode voltage; The second is to collect the voltage value at the contact point (i.e., a d).

In this paper, the ADS7843 chip produced by BB (Burr-Brown) is used as an example to introduce the implementation of touch screen control.

At present, there are two kinds of screens that are more commonly used, one is a capacitive screen, one is a resistive screen, most of the earliest touch screens are resistive screens, which can not only be operated with fingers, but also can be operated with fingernails or hard stylus and other items, and now most of the mobile phones use capacitive screens, which can be operated with fingers or special stylus.

First of all, the resistance screen, the touch area of this screen can be divided into two layers, the upper and lower layers of the screen are distributed with a lot of vertical and vertical wires, respectively representing X coordinates and Y coordinates, when your fingers or other items touch the screen, it will press the screen, so as to connect the upper and lower screens, this is the procedure, you can judge the position you press according to the position voltage and other data of the wire connection, so as to play the effect of touch.

The capacitive screen is operated by sensing the static electricity that comes with the human body, generally speaking, there are devices that induce static electricity at the four corners of the screen, when your finger is pressed, these devices will calculate the distance between your finger and the device, so as to judge the position you are pressing on the screen, you may have heard that because static electricity causes the touch failure of the mobile phone, due to the interference of static electricity, the mobile phone may not be able to correctly identify the position of your fingers, resulting in touch failure.

The touch screen needs to be used to achieve touch response on the mobile phone screen, and now the capacitive touch screen is used on the mobile phone screen.

The capacitive touch screen can realize multi-touch, sensitive operation, and has the characteristics of high durability and difficulty in mistouching. The capacitive touch screen can only operate when sensing the current of the human body, avoiding the touch of other items, and performing well in dustproof, waterproof, wear-resistant, etc., the capacitive touch screen has a long life and does not need pressure to generate signals, and can be achieved by direct touch.

There will be some interference factors in the use of capacitive TP touch screen, electrostatic discharge, in a strong magnetic field, oil, sweat, water vapor and other conductive substances attached to the screen may permanently damage the capacitive screen. When the ambient temperature and humidity do not meet the working environment, or the voltage is low and unstable, physical impact and vibration and other factors will cause damage to the capacitive touch screen, resulting in the scrapping of the capacitive screen. Therefore, capacitive TP touch screens need to be tested.

Selecting the appropriate test module in the test can play a good connection function, and can play an excellent role in the on-current and transmission signal. The high-current shrapnel microneedle module is a test connection module suitable for TP touch screen testing. First of all, the one-piece structural design and the material of nickel alloy beryllium copper make the high-current shrapnel microneedle module both light and tough, not easy to break the needle, high service life, and strong overcurrent ability.

In the past, it was basically a resistive screen, and the touch reaction was realized through the change of resistance value after pressing, but now it is basically a capacitive screen, and the touch reaction is realized by inducing the change of capacitance after touching.

There are transparent conductive wires in the touch screen, press the horizontal row 5 to 10 rows and the vertical row is also, the finger presses up, changes the capacitance between the two rows of lines, and the processing IC confirms the position of the touch according to the position of the horizontal and vertical capacitance changes, the position is defined by the mobile phone software, and the function defined by the position you touch is interpreted and executed by the mobile phone software, and the changed capacitance position is like a physical button connected to a similar definition. May it be so.

What technology does the phone screen pass through? It can be controlled through the Android system and this uh new film and this panel, so the mobile phone screen can realize touch control, which means that the mobile phone can pass through the above steps, who said that science and technology are advanced people in the advanced circle, and who said that variety shows can be realized? I was in the R&D room when I was in level 5 and level 6.

There are several ways.

Thermistor sensing touch screen.

Capacitive touch screen.

Pressure-sensitive touch screen.

Surface voice-activated touchscreen.

Crazy, crazy, trouble your parents, parents.

The touch screen of the mobile phone is equivalent to a sensing device, which can receive the input signal, and then drive it through the haptic feedback system to create vivid audio and video effects on the LCD screen. The mobile phone touch screen is one of the components of the mobile phone screen, which has the advantages of being durable, easy to use and fast response.

Capacitive touch screens work by using the body's current to sense. When the user touches the mobile phone screen, the human electric field will form a coupling current with the surface of the mobile phone touch screen, and this current will flow out of the electrodes on the four corners of the mobile phone touch screen, and the controller can obtain the position of the touch point through the accurate calculation of the proportion of these four currents.

The mobile phone touch screen reliability test item can be divided into three parts: optical & electrical performance test, mechanical performance test and environmental reliability test. In the test, a dome microneedle module is required to play a connection role, which can provide a stable connection function and can also transmit high current.

The current transmission is stable in the range of 1-50A, with no current attenuation and strong overcurrent capacity, which ensures the stability of the mobile phone touch screen test.