How does the CCD Array in the sharp GP2D12 infrared sensor calculate angles/distance? - Electronic Circuits Projects Diagrams Free

fantabulous68 · 21st October 2009, 04:42 PM

This is what i know:

If the surface of the liquid/object is within range and in line with the IR beam, reflected light forms an image on a linear CCD array in the receiver.

Can someone give me a more in depth explanation, or relevant links would be useful too.

fantabulous68 · 22nd October 2009, 10:15 AM

lol is that question hard

? My examiner asked me that at my presentation yesterday

I said it uses Triangulation

, but he wanted to know how

ericgibbs · 22nd October 2009, 10:49 AM

Quote:

Originally Posted by fantabulous68

lol is that question hard

? My examiner asked me that at my presentation yesterday

hi Ms F.

Look thru this link.

Sharp GP2D12

fantabulous68 · 22nd October 2009, 12:23 PM

Quote:

Look thru this link.

Quote:

Sharp GP2D12

I have that link already and lol it doesn't even mention the word ccd array.

Try ctrl+f

ccd or ctrl+f array

But thanks for trying

Mr Gibbs

Quote:

Ok with google i found this info:
This sensor works by sending a pulse of IR light through its emitter. If the light hits an object it is reflected back, creating a triangle between the send, receive, and reflection point. The emitter for this sensor is a precision lens that reflects light onto a small linear CCD array. The way the light falls on the CCD array makes it possible to calculate the distance from the object.

Quote:

• The GP2D12 uses an IR emitter and a small linear CCD array detector that is 3/4" away from the IR emitter, in order to calculate the distance an object is away from the sensor. It can detect distances that are around 4" to 30" away from the sensor. The IR emitted sends off some IR light and the light will be picked up by the detector. Between the IR emitter, the point of reflection at the object the light hits, and then the detector, a triangle is formed and from this the distance can be calculated. The angles in this triangle will change depending on the distance of the object and thus we can calculate the distances using the angles.

but i want a more in depth explanation, somebody, anybody,

im gonna try wikipaedia now

ericgibbs · 22nd October 2009, 12:40 PM

Quote:

Originally Posted by fantabulous68

I have that link already and lol it doesn't even mention the word ccd array.

Try ctrl+f

ccd or ctrl+f array

Wooo Ms F that smarts!!
The optics dont form a true image on the CCD just an illuminated area offset at an angle from the source.
The GP2D12 outputs a signal proportional to this offset which is related to the angle.

Using fairly simple trig from these angles a range/distance can be calculated.

Roborugby Distance Sensor

fantabulous68 · 22nd October 2009, 01:38 PM

Quote:

Wooo Ms F that smarts!!

lol is that sarcasm

Thanx Mr Gibbs, thats a good explanation

. I have a better understanding now.
WIKIPAEDIA:

Quote:

A charge-coupled device (CCD) is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time. Technically, CCDs are implemented as shift registers that move charge between capacative bins in the device, with the shift allowing for the transfer of charge between bins.

Often the device is integrated with a sensor, such as a photoelectric device to produce the charge that is being read, thus making the CCD a major technology where the conversion of images into a digital signal is required. Although CCDs are not the only technology to allow for light detection, CCDs are widely used in professional, medical, and scientific applications where high-quality image data is required.

Quote:

A CCD is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges are converted to voltage one pixel at a time as they are read from the chip. Additional circuitry in the camera converts the voltage into digital information.

Mr RB · 23rd October 2009, 07:50 AM

That's not a bad picture. They've even got the trasmitted beam at 90' (which is correct) lots of the pictures you see for the sharp sensors get that bit wrong.

heloiseaze · 14th November 2009, 02:48 PM

If the transmitted beam is at 90',well, when it meets a perfect plane surface, as the picture shows it, how can it be reflected with an angle different from 0?

Mr RB · 14th November 2009, 03:17 PM

Who said the plane surface was perfect?

heloiseaze · 16th November 2009, 05:08 PM

Oh yes, you are right, I have forgotten that. But, if the surface is a plane mirror, well, does it mean that the captor can't calculate the distance?

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21st October 2009, 04:42 PM	#1
fantabulous68	How does the CCD Array in the sharp GP2D12 infrared sensor calculate angles/distance? This is what i know: If the surface of the liquid/object is within range and in line with the IR beam, reflected light forms an image on a linear CCD array in the receiver. Can someone give me a more in depth explanation, or relevant links would be useful too. __________________ Learn without thinking begets ignorance. Think without learning is dangerous.

22nd October 2009, 10:15 AM	#2
fantabulous68	lol is that question hard? My examiner asked me that at my presentation yesterday I said it uses Triangulation, but he wanted to know how __________________ Learn without thinking begets ignorance. Think without learning is dangerous. Last edited by fantabulous68; 22nd October 2009 at 02:15 PM.

23rd October 2009, 07:50 AM	#7
Mr RB	That's not a bad picture. They've even got the trasmitted beam at 90' (which is correct) lots of the pictures you see for the sharp sensors get that bit wrong.

14th November 2009, 02:48 PM	#8
heloiseaze	If the transmitted beam is at 90',well, when it meets a perfect plane surface, as the picture shows it, how can it be reflected with an angle different from 0?

14th November 2009, 03:17 PM	#9
Mr RB	Who said the plane surface was perfect?

16th November 2009, 05:08 PM	#10
heloiseaze	Oh yes, you are right, I have forgotten that. But, if the surface is a plane mirror, well, does it mean that the captor can't calculate the distance? Last edited by heloiseaze; 16th November 2009 at 05:09 PM.