Transmissive optical encoder's output signals

Thread Starter

nqchanh194

Joined Jul 5, 2013
27
I can see that you started a new thread discussing your project, instead of just your optical encoder question. Would you prefer we continued this discussion there?
It's okay. I just want the others to know more about my project.

About the Hall sensor, I've read datasheet of a particular one. Please refer to the attachment.
Please take a look on page 9. As you can see in figure 10, the output value is not linear at both sides of the magnet.
Therefore, if I want to apply for measuring 20 cm, I will have to use a magnet longer than 20 cm.
Is that right ? Is there any solution else for this case ?
 

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cmartinez

Joined Jan 17, 2007
8,220
It's okay. I just want the others to know more about my project.

About the Hall sensor, I've read datasheet of a particular one. Please refer to the attachment.
Please take a look on page 9. As you can see in figure 10, the output value is not linear at both sides of the magnet.
Therefore, if I want to apply for measuring 20 cm, I will have to use a magnet longer than 20 cm.
Is that right ? Is there any solution else for this case ?
Yes, at least in theory... but in practice I think you might find several hurdles... I highly doubt that a magnet that long would have an evenly distributed magnetic field, in the first place... you would probably have to calibrate for each particular magnet that you used per instrument...
But my original suggestion was about measuring a distance to a magnet, not along a magnet. There are very good sensors out there able to measure extremely weak magnetic fields. I suggest you study that possibility as well.
 
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