Found a modern day field sequential color tv

[jr_tech]

Originally Posted by etype2

JVC says the three color RGB filters are crystal clear.

Scratching my head over that one, while the transmission of each filter might be fairly good at the selected color, the transmission of white field through the entire stack of filters, cells and linear polarizers is likely less than 20%, if it is anything like the Tektronix LCCS design. The CRT in the Tek scopes, without the LCCS stack was quite bright!
Also IIRC, the Tek design actually used magenta, yellow and cyan filters, so perhaps JVC improved in the design?

jr

[etype2]

Originally Posted by jr_tech

Scratching my head over that one, while the transmission of each filter might be fairly good at the selected color, the transmission of white field through the entire stack of filters, cells and linear polarizers is likely less than 20%, if it is anything like the Tektronix LCCS design. The CRT in the Tek scopes, without the LCCS stack was quite bright!
Also IIRC, the Tek design actually used magenta, yellow and cyan filters, so perhaps JVC improved in the design?

jr

A portion of text taken from JVC brochure:

"Unlike a conventional CRT screen, where the picture is written on the back of a light-absorbing layer, the TM-L500PN features a bright backlit screen seen through crystal-clear filters. Even if ambient light shines on the screen, the picture loses none on its contrast or clarity."

Maybe taking a bit of liberty here in their description.

[etype2]

BTW, what does IIRC mean?

See this all the time in this forum, but have been embarrassed to ask. I get what IMHO means. LOL. (old guy here)

[Electronic M]

Originally Posted by etype2

BTW, what does IIRC mean?

See this all the time in this forum, but have been embarrassed to ask. I get what IMHO means. LOL. (old guy here)

Google knows all, and I consult them if I don't know a word or abbreviation....That said IIRC = If I Recall Correctly.

[jr_tech]

If I remember correctly, it means "if I remember/recall correctly".

jr

[etype2]

Cfm tu :-)

[Electronic M]

Originally Posted by etype2

The Sync. input is 50HZ x 3 = 150HZ. The black and white CRT frequency is 15.625 x 3 = 46.875 kHZ. One field displays 3 images (RGB) in 1/50th of a second.

Unless they are converting form NTSC to PAL there is no way it could have 50Hz synch....59Hz I'd buy, but 50Hz no way.

[Dave A]

A few observations and questions...and thanks for the input from all with a few photos added tonight to hopefully help me figure this out.

Jr...The first is that the LCD shutters are variable in chroma density on this set depending on the user menu chroma setting. Not fixed color filters like a DLP or a Col-R-Tel. When I got this and the manual, I found the RGB shutter gains...on the side of the body...and did a by-eye setup to BW with the chroma down. It is as close as it gets to BW by my aging eyes. The camera white balance is a bit off. BW here. The shutters look clear at this point and it shows the finest scan lines I have ever seen. I can shine a flashlight through the front and easily see the CRT. 100% transmission to me in BW. The addition of color will change that to the users degree of chroma gain.

I added a "blue check" menu button photo from the front button selection. "Blue check" is an old, cheap way to set bars on a color monitor without a scope. This should also represent a frame/field of the blue processing and does show the luminance values in the blue space for it's moment in RGB color. R and G should be the same and sequentially add to balanced color in the scan at that moment. And your persistence of vision kicks in at this point.

etype...you mention two filters and the block shows one eprom going to two buffers before the LCD shutter. Is this not RGB or am I missing something? The video buffer shows two dram. Is this some kind of color +/- thing going on? Help me with the two shutter concept.

And help me more with the scan/field rate. I think I am close but a blow-by-blow of a frame in RGB/LCD processing would help.

Gotta go now so I can watch the 1960 Peter Pan in JVC field-sequential color. I am seeing colors I have never seen before.

[jhalphen]

Hi to All,

For those who have not downloaded/watched the JVC's advertising brochure, here are zoomed shots showing the LCD color shutter system.

Note the use of the term LCCS in the 3rd slide, therefore implying direct parenthood with the Tektronix color oscilloscope technology.

As for the switching speed, my opinion is that it is always 3x the incoming signal frequency, therefore 3x60 in NTSC, 3x50 in PAL.
Being a digital design, no problem there.

Best Regards

jhalphen
Paris/France

[old_tv_nut]

Link to a patent application:

http://www.google.com/patents/EP0157523A2?cl=en

[etype2]

Originally Posted by Electronic M

Unless they are converting form NTSC to PAL there is no way it could have 50Hz synch....59Hz I'd buy, but 50Hz no way.

Jerome is correct. I quoted a European publication.

[etype2]

Found a Patent that was assigned to JVC by Hughes. This one seems to be more closely aligned to the set under discussion.

http://www.google.com/patents/US3781465

[old_tv_nut]

You can get a clearer image at the Us patent office site. go to:
http://patft.uspto.gov/netahtml/PTO/patimg.htm
and enter the number 3781465

[etype2]

old TV nut,

Can't get the viewer to work on my iPad Air. Probably works okay on Windows. If you click on the "download the PDF" on the link I provided, you will get the original document with drawings.

[jr_tech]

Originally Posted by Dave A

Jr...The first is that the LCD shutters are variable in chroma density on this set depending on the user menu chroma setting. Not fixed color filters like a DLP or a Col-R-Tel. When I got this and the manual, I found the RGB shutter gains...on the side of the body...and did a by-eye setup to BW with the chroma down.

So when you adjust "shutter gains" does the waveform/duty cycle to the liquid crystal cells change, or does the brightness/contrast of the CRT in each color field change?

Who is going to be the first to cut one apart so we can figure out how the JVC color sutter works?
Some questions:

1. 2 or 3 liquid crystal cells in the assembly?
2. RGB or MYC colored filters/cells?
3. External polarized color filters on the liquid crystal cells, or some sort of "colored magic liquid crystal goo" fill in the cells?

jr