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The principle and maintenance of mobile phone touch screen

The principle and maintenance of mobile phone touch screen


The mainstream of mobile phone screen, is also the only popular capacitive touch screen


Capacitive screen is introduced:


Capacitive screen is a four layer composite glass screen, the inner surface of the glass screen and interlayer

coating a layer of ITO, the outermost layer is only 0.0015 mm thick silica glass coating, laminated ITO coating

for working face, four Angle of draw out four electrodes, inner ITO layer to screen to ensure that the working

environment.When a user capacitive touch screen, the electric field due to the human body, your fingers and

face form a coupling capacitance, because the working plane to have a high frequency signal, so the fingers

on a very small current, respectively from the current screen in the four corners of the electrode, and

theoretically through the four electrodes with the finger to the four corners of the current is proportional

to the distance, the controller based on the four current proportion of fine calculation, it is concluded that



Principle and maintenance of mobile phone touch screen, replacement and substitution method


Now we are in the maintenance of mobile phone, replace the touch screen more and more, because now

more popular straight board of mobile phone, and touch screen is very easy to damage of components,

a proportion of maintenance is very high at present, I today from the principle to detect the change

(substitution) to also do not know in touch friend about my personal experience, the maintenance of

hopes to be helpful to the novice, if there is anything wrong, I hope you give me glad.


A.The principle of mobile phone touch screen


Generally we see a touch screen is has four legs, we respectively the X, X1, Y, Y1.Where X and Y, the X1 and

Y1, respectively is a group, a group responsible for the horizontal coordinate detection, a group is

responsible for the longitudinal coordinate testing, because each line according to the length of the

distance resistance value is different, so, when we order a bit arbitrary position, will be X and Y, the X1 and

Y1, two sets of intersecting line, because the position of each point distance is not the same, so the

intersection point of resistance is a unique value, the CPU is based on the value judgment on what that

corresponds to the function.


So we can know, by the touch screen function not normal fault principle, no more than 3 points:


1.Touch screen caused by external force damage or into liquid such as touch screen itself cannot be

correctly on the X axis and Y axis signals into the CPU;


2.Cannot touch between CPU and circuits to transmit signal, including wire break or between the

damage of the components;


3.Be able to transmit the touch screen to CPU signal is interpreted correctly, including CPU itself damage

and word stock program disorder.


B.Mobile phone screen replacement and substitution


Currently on the market there are two kinds of touch screen according to the principle of the points, is a

kind of resistance type, is a kind of capacitor, we are common resistance type, so we are to explain with

resistive touch screens.Now we can see the touch screen can say is a great variety, different size, effective

control of display area, the shortcut key position is different, and so on, but in fact can be substitution,

doesn't have to buy and the original machine go line the same size, but also can't be bought to all.In

general, as long as close to the size of the can complete substitution, is the location of the 4 lines is not

the same, at most four connection methods, we use the benzene solution connection would be up to 4

times can pick up right!


Now introduce substitution method, we assume that X and Y * line is responsible for the transverse

detection, which is around on the screen;The X1 and Y1 axis / * line to take charge of the longitudinal

test, which is on the screen.In order to convenient we understand, I put the X, Y, X1, Y1 numbered four

wires, on behalf of line 1, 2, 3, 4, respectively.


We first assume that the first case, will be received on the X1, X or Y received Y1, thus creates two

intersections group line can produce, so the touch screen is completely unresponsive.(some mobile

phones have reflected, the phenomenon is disorder), the solution: the line 1 and 2, 3, and 4 line switch

on, straight to pick out the reaction.


The second case, the X from Y, X1 to the Y1, so it is turned upside down, but between each group of

lines or intersections can click, so pick up words will cause touchscreen completely disorder, the upper

left click reaction on the lower right corner.But we met in a touch screen is the reflect how to do?Will

line 1 and 3, 2, and 4 line switch, switch this later, there will be at least 100% of a shaft response is

correct, such as the up and down, or about one of the shaft can correctly identify.


The third case, by one of two groups of lines link is wrong, for example, X from Y or X1 received Y1,

it will cause one click on the opposite direction of axis, such as press, according to the left is right,

the solution is to first assumption is wrong, 1 and 3 line switch we try, if the callback or bad, but

completely disordered, restore fair, then switch the line 2 and 4, 100% will solve the problem!



TAG:  mobile phone touch screen
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