What is the filter in front of CCD?

J

Jeff

Guest
Hi,

I am trying to repair my camcorder (sony TRV-17) which dropped into
water for several minutes. Until now everything I've done seems right
except one silly big mistake.

I once repaired some electronics instruments and in recent years I
design high speed analog and digital circuits, I also have drawn some
tricky PCBs successfully. But I never disassembled a delicate MiniDV,
so I wanted to consult some professionals first. After the accident,
the next day I went to the local offical sony repair shop. The manager
gave me some useful advices, but one of them was just curious to me.
He said I should paint a layer of oil on the PCB as soon as possible
to prevent oxidation erodes the traces and pins of chips. That day I
disassembled the cam and still found curious about the idea of oil.
The second day I want to the shop again to ensure the idea. The
manager told me the lake water was not very pure, so oxidation was
inevitable. The only way was a thin layer of oil to isolate oxygen to
act with the contamination. I should process all the pcb patiently to
prevent erosion in the future.

I followed the procedure to oil all the pcb. After posted questions on
this newsgroup I thought the thoroughly dry PCB was more reasonable.
The oil layer was just to prevent water evaporate. So, I clean the oil
and bake the PCB in the oven for one day. Becaues I oil PCBs and clean
them in such a hurry, I careless contaminated the transparent
colorless filter attached to a sqare black plastic base on top of CCD.
I tried to solve the contamination, to make things worse, the filter
dropped off. Then I did know the lens are very delicate, but don't
take care too much to CCD just to think it is a special kind of chip
making light-electrical signal conversion.

Now I am really regret the silly mistake I had done. I should spend
several days to post question and search relative thread in
newsgroups. Now I have learned some about CCD, but still don't what
damage to CCD in my situation. In my previous post, I have learned a
lot from the replies, especially from Jeff Liebermann. Thank all of
you.

Now my question is:

..What is the function of the filter?
..What damage to the CCD now?

BTW, my camera dropped to water with my cam at the same time. After
cleaning and drying, the camera works again. This gives some
inspiration to repaire my cam. I find the damage was mainly at the
power supplier part(one resistor and one fuse blown out).



Could you help me?


Any reply is appreciated.
 
Check out www.howstuffworks.com. I remember seeing some good
descriptions on how CCDs and the filters work.

Jeff wrote:
Hi,

I am trying to repair my camcorder (sony TRV-17) which dropped into
water for several minutes. Until now everything I've done seems right
except one silly big mistake.

I once repaired some electronics instruments and in recent years I
design high speed analog and digital circuits, I also have drawn some
tricky PCBs successfully. But I never disassembled a delicate MiniDV,
so I wanted to consult some professionals first. After the accident,
the next day I went to the local offical sony repair shop. The manager
gave me some useful advices, but one of them was just curious to me.
He said I should paint a layer of oil on the PCB as soon as possible
to prevent oxidation erodes the traces and pins of chips. That day I
disassembled the cam and still found curious about the idea of oil.
The second day I want to the shop again to ensure the idea. The
manager told me the lake water was not very pure, so oxidation was
inevitable. The only way was a thin layer of oil to isolate oxygen to
act with the contamination. I should process all the pcb patiently to
prevent erosion in the future.

I followed the procedure to oil all the pcb. After posted questions on
this newsgroup I thought the thoroughly dry PCB was more reasonable.
The oil layer was just to prevent water evaporate. So, I clean the oil
and bake the PCB in the oven for one day. Becaues I oil PCBs and clean
them in such a hurry, I careless contaminated the transparent
colorless filter attached to a sqare black plastic base on top of CCD.
I tried to solve the contamination, to make things worse, the filter
dropped off. Then I did know the lens are very delicate, but don't
take care too much to CCD just to think it is a special kind of chip
making light-electrical signal conversion.

Now I am really regret the silly mistake I had done. I should spend
several days to post question and search relative thread in
newsgroups. Now I have learned some about CCD, but still don't what
damage to CCD in my situation. In my previous post, I have learned a
lot from the replies, especially from Jeff Liebermann. Thank all of
you.

Now my question is:

.What is the function of the filter?
.What damage to the CCD now?

BTW, my camera dropped to water with my cam at the same time. After
cleaning and drying, the camera works again. This gives some
inspiration to repaire my cam. I find the damage was mainly at the
power supplier part(one resistor and one fuse blown out).



Could you help me?


Any reply is appreciated.
Click to expand...
 
That filter is actually a difuser, it actually blurs the image, but only a
little bit. It's there to keep video components above about 4.4Mhz from
confusing the color mosaic decoder. The camera is usable without it, but you
might notice some strange color abberations on scenes with alot of detail.

This filter may have other function(s) on your unit, so it might be a good idea
to try to get one since you're going to all the trouble in the first place.

Brings me to a conversation I had the other day with a guy helping me do some
remodeling on my Mother's bathroom. He said he assumed I wanted to do it right,
I replied, no, I don't want to do it right, but I'll do it right so I don''t
have to do it again.

In other words, put the filter in or you might find yourself tearing the thing
down again. I've never run a camera lacking the filter, so I don't know just
how bad it gets, also it will probably throw off the backfocus adjustment and
that is not alot of fun. The backfocus makes the zoom function track properly.

JURB
 
JURB6006 wrote:
That filter is actually a difuser, it actually blurs the image, but only a
little bit. It's there to keep video components above about 4.4Mhz from
confusing the color mosaic decoder. The camera is usable without it, but you
might notice some strange color abberations on scenes with alot of detail.

This filter may have other function(s) on your unit, so it might be a good idea
to try to get one since you're going to all the trouble in the first place.

Brings me to a conversation I had the other day with a guy helping me do some
remodeling on my Mother's bathroom. He said he assumed I wanted to do it right,
I replied, no, I don't want to do it right, but I'll do it right so I don''t
have to do it again.

In other words, put the filter in or you might find yourself tearing the thing
down again. I've never run a camera lacking the filter, so I don't know just
how bad it gets, also it will probably throw off the backfocus adjustment and
that is not alot of fun. The backfocus makes the zoom function track properly.

JURB
Click to expand...
Don't they also use the filter to filter out infrared?
mike

--
Bunch of stuff For Sale and Wanted at the link below.
laptops and parts Test Equipment
4in/400Wout ham linear amp.
Honda CB-125S
400cc Dirt Bike 2003 miles $550
Police Scanner, Color LCD overhead projector
Tek 2465 $800, ham radio, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/
 
"JURB6006" bravely wrote to "All" (02 Oct 03 00:40:36)
--- on the heady topic of "Re: What is the filter in front of CCD?"

Could it be the filter is there so it can't copy money?

JU> From: jurb6006@aol.com (JURB6006)

JU> That filter is actually a difuser, it actually blurs the image, but
JU> only a little bit. It's there to keep video components above about
JU> 4.4Mhz from confusing the color mosaic decoder. The camera is usable
JU> without it, but you might notice some strange color abberations on
JU> scenes with alot of detail.

.... Luxuriantly hand-crafted from the finest ASCII!
 
"Asimov" <Asimov@-removethis-bbs.juxtaposition.dynip.com> writes:

"JURB6006" bravely wrote to "All" (02 Oct 03 00:40:36)
--- on the heady topic of "Re: What is the filter in front of CCD?"

Could it be the filter is there so it can't copy money?
Click to expand...
The one under discussion is probably an antialiasing filter as described
in another post - it smooths the spatial frequency response in a precise
manner. Some cameras use a plate of lithium niobate, a birefringent
material, for this purpose.

There's also probably an IR filter.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.
 
Thank all of you.

In addition, I made this mistake because I misremembered the CCD in
digital camera could be cleaned easily from the newsgroup about
digital camera. After the accident, all I get from the newsgroup about
the CCD is very strict, even seems more than the optical lens. I think
the filter and the CCD chip would have some dirt or some other foreign
speck. Could you tell me how to clean it? Use the optical lens fluid,
or some thing else? Or, better not to touch it at all?



Thanks.

Have a good day.
 
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