What kind of encoder is used in computer mouse?

[bittware]

mouse encoder

Hello experts,
I want to what kind of encoder is used in mechanical PS/2 mouse.
I intend to find some clues about IR emitter and encoder from several disassembled mouses, but all the signs are erased. So I cant find corresponding datasheets of these units.
My final goal is to use mouse encoder as motor encoder. Because I am not sure if this kind of encoder is feasible for relative high speed rotary encoding, I must know its property(such as interface&responding speed) before starting make prototype.
Hope someone give me some clues and suggestion.
Thank you in advance!

 

[kendr_za]

encoder mouse

I think most PS/2 mice use some sort of microcontroller or ASIC. I dont think you would be able to buy the controller off the shelf. Their workings are pretty simple tho. The position is calculated by a simple rotary encoder, every time the notched wheel passes through the sensor, the sensor outputs a pulse. All you need to do is to count the pulses (and maybe the pulse width) to find out direction and speed.

 

[FoxyRick]

kind encoder

Hi bittware,

the IR encoder in a mouse is a quadrature encoder. The unit outputs two pulses for 'step', with 90 degrees phase difference. This allows sensing both direction of movement (from which signal edge leads) and speed.

If you only need to sense speed (you know ehich way your motor turns) you don't need quadrature. It is probably simpler to just use the slotted wheel from the mouse and your own IR LED and sensor.

I don't think you should have a problem with the speed of the LED and sensor, unless your motor is spinning at 100,000's rpm (if it is this fast, the sensor is the least of your problems)

Cheers,
FoxyRick.

 

[eltonjohn]

computer encoder

look at the microchip website they have an appnote on how to design a mouse using a pic .. all is there!

 

[ChAoS666]

mouse sensor encoder

look at an-681 datasheet