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  #46  
Old 01-25-2015, 05:29 PM
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I'm not a digital video designer...I just play one on tv...and own one of these things that I keep looking at to figure it out. I need to figure out the difference between a filter and a shutter.

JR...my first use of "RGB shutters" in my text should be more like a "RGB drive" adjustment and needs correcting via Jerome's pix. The RGB should be a filter. His shows two shutters sandwiched in between (probably polarized).

I can see how a 3x modulated RGB tube pushes color through variable density filters but I am missing what the shutters do.

The Hughes patent look similar but only has one polarized shutter.

I have to grab the printout of the block and scan it. Stay tuned.
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  #47  
Old 01-25-2015, 08:40 PM
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Quote:
Originally Posted by Dave A View Post
I need to figure out the difference between a filter and a shutter...
I am missing what the shutters do.
Well, I may confuse things a bit with a kinda High School science class explanation, but I will take a stab at it:

1. A filter may be as simple as the colored filters used to select a specific portion of a light spectrum, for example a blue filter placed in front of a "white" light source to produce blue illumination.

2. A liquid crystal cell is usually a couple pieces of glass with transparent electrodes (usually tin oxide) arranged in a specific pattern to control the orientation of liquid crystal material that is contained between the two glass pieces, by applying voltage to the electrodes.

3. Color shutters are a combination of LC cells, polarized filters and color polarized filters that can switch the color transmitted by applying voltage to the cell.
Imagine this high school experiment... take 2 pieces of polarized material and observe a "white" light source through the two filters... if you rotate one filter with respect to the other, you will observe a minimum and maximum transmission of light at 90 degrees rotation. If one of the filters is, say blue color polarized material, you will observe a change from white light to blue light as you rotate the filters 90 degrees. Now if instead of mechanically rotating the polarized filters 90 degrees with respect to one another you placed a liquid crystal cell designed to rotate polarized light 90 degrees when voltage is applied to it, you could produce the same optical changes by merely flipping a switch.

jr
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  #48  
Old 01-26-2015, 10:00 AM
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Originally Posted by jr_tech View Post
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

Question 1. 3
Question 2. External based on the below comment, however JVC says there are two? polarizers and two shutters? Uncertain here.

From JVC press release: "single electron gun aimed through red light, green light and blue light filters, each separated by a liquid crystal shutter."

Jerome's illustrations were from a JVC brochure.

If you read through the Hughes/JVC Patent, it talks about your other question. It appears that JVC made some enhancements by adding a second polarizer.
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Last edited by etype2; 01-26-2015 at 10:26 AM.
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  #49  
Old 01-26-2015, 08:40 PM
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The patent has three LC layers. Each one can be made either clear or a primary color (red in one, green in the other, blue in the third) by orienting the liquid crystal dyes perpendicular to the light path (colored) or parallel (clear). I take it that the dye molecules also mainly affect one axis of polarization when they are perpendicular to the light path, so using polarizers makes the color effect stronger.

So, two are clear on any given field and one is a primary (additive) color. This seems to be how the TV works, as the brochure talks about clear states and shows three colors. The brochure also makes the usual illustrator's /printer's mistake of showing the primary images as red and white instead of red and black, etc. This same mistake was made in early illustrations of how the trinoscope worked.
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  #50  
Old 01-26-2015, 08:47 PM
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The difference between a filter and a shutter:

Filter states: clear, color (in the patent, the color state is: not transmitting light of two primary colors, but only of one primary color). It is also possible to make filters that would stop one primary color and transmit two, so the three would individually be yellow, cyan, and magenta. Then, to get additive red, green blue, you would have to activate two filters at a time.

Shutter states: clear, black (the color of the color state is black - not transmitting any light of any color).
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  #51  
Old 05-06-2015, 05:14 PM
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Got the idea to see what we would see, if I took a slow motion video of the JVC field sequential receiver/monitor with an iPhone 6 plus.

Posted to You Tube. http://youtu.be/GTDpVZWQaFE

You can see the sequential switching going on.
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  #52  
Old 05-06-2015, 07:49 PM
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The old trick to seeing the colors is to spread your fingers on one hand and wave them in front of the tube/wheel. You will see the colors.

etype...can you do a high-speed recording? That would record each color for a few frames depending on the speed. Playback would be slo-mo and show each in full.
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  #53  
Old 05-06-2015, 08:36 PM
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Quote:
Originally Posted by Dave A View Post
etype...can you do a high-speed recording? That would record each color for a few frames depending on the speed. Playback would be slo-mo and show each in full.

I believe we did that by accident. I was recording at normal 1080P frame rate, but in slow motion, 240 fps and when the video played back, the first 20 seconds or so was in normal speed, but showed the slow progression from bottom to top of screen of each color, red, green and blue. One color filled the screen and slowly transitioned to the next color. I can post that video if interested.
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  #54  
Old 05-06-2015, 09:25 PM
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Great minds accidentally think alike. I think that 20 seconds would show the real progression of RGB across the BW tube. The bottom to top is interesting. Maybe a frame rate collision.
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Last edited by Dave A; 05-06-2015 at 09:27 PM. Reason: text
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  #55  
Old 05-06-2015, 10:10 PM
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Someone already mentioned the Tektronix NuColor displays. While this thread was sleeping for several months I actually ended up finding one of their standalone models. Give it a modified composite signal and boom, you got color.



I really gotta take better photos of this thing.
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  #56  
Old 05-07-2015, 11:30 AM
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Quote:
Originally Posted by Dave A View Post
Great minds accidentally think alike. I think that 20 seconds would show the real progression of RGB across the BW tube. The bottom to top is interesting. Maybe a frame rate collision.
Posted new video with description showing this.
http://youtu.be/sUFFqBhGUgY
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  #57  
Old 05-07-2015, 12:09 PM
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Last edited by andy; 11-20-2021 at 03:35 PM.
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  #58  
Old 05-07-2015, 12:45 PM
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NU900M

This ebay listing has great pics and a spec sheet.
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  #59  
Old 04-22-2022, 01:33 PM
Quixylvre Quixylvre is offline
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If OP still has this monitor, I'm curious what its input lag is like, relative to, say, a Trinitron PVM, or even the IDX-5000 Indextron PVM? Mayhaps a test could be conducted with such monitors daisy-chained to all display video from a single composite video source?
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  #60  
Old 04-24-2022, 07:49 PM
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The OP is here and still has the monitor in a dubbing rack. I will try to build a comparison in real time via a DA that would feed the monitors. The only other small size set I have might be my KV-5000 via RF. That should be real time. And I will try to add a slo-mo like Marshall just for fun. Stay tuned.
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