Hi there. Thanks for the offer Fiat1. I have two motors both from old printers. One has 6 mirror facets and is crystal controlled to run at 7701 rpm at 24 vdc but it will run slower if I lower the dc voltage. The other is rated at 10500 rpm has 8 mirror facets and needs a squarewave to run it. If I give it 500 Hz it runs at 500 rpm. If I give it 6000 Hz it runs at 6000 rpm. Very handy sort of circuit you have there Fiat1. Send me an email if you like. Some of you may be wondering why I am playing around with a silly little mechanical system which turns out a raster so dim you can hardly see it. Several reasons. Its a prototye system to see if it works. Potentially better definition than a LCD. I know modern LCD are extremely good but can you get modern ones. Adjustable format by altering the polygon speed. Dont need a projection lens.
Cheap to play with. All I am using so far cost me $20 or so. The way I look at it is I have to get a visible steady raster on my projection screen first. Even if the screen is only 4 feet away and the raster is 1 foot wide it is a start. Its good mental exercise every day while cutting the grass or something I am thinking how to do it without spending big money. Also lots of things I dont know how they work so I have to look it up on the internet.
At the moment I am thinking about interlacing. I can do it with a piezoelectric deflector. Just shift the main source beam a small amount each field. Or an electrostatic small movement mirror. Doesn't need to be fast. A small mirror on a loudspeaker might work. The reason I have to think about this is using the projector as a large tv the tv station sends lines 1 3 5 etc up to line 312 and a half. Then it sends lines 2 4 6 8 etc. I could buy a computer board to store the lines and output then in the correct sequence. Have to see how much they are.
Cheap to play with. All I am using so far cost me $20 or so. The way I look at it is I have to get a visible steady raster on my projection screen first. Even if the screen is only 4 feet away and the raster is 1 foot wide it is a start. Its good mental exercise every day while cutting the grass or something I am thinking how to do it without spending big money. Also lots of things I dont know how they work so I have to look it up on the internet.
At the moment I am thinking about interlacing. I can do it with a piezoelectric deflector. Just shift the main source beam a small amount each field. Or an electrostatic small movement mirror. Doesn't need to be fast. A small mirror on a loudspeaker might work. The reason I have to think about this is using the projector as a large tv the tv station sends lines 1 3 5 etc up to line 312 and a half. Then it sends lines 2 4 6 8 etc. I could buy a computer board to store the lines and output then in the correct sequence. Have to see how much they are.
If you click my profile button Fiat1 it will show you about me and there is a line there to send me an email. I am sorry I do not know how you can change your email address. Perhaps someone can help you or you could contact the administrator. I am still thinking about the interlace problem. A computer card to do the job will cost me NZ$550-NZ$750 defending on the features, and since I dont need one for any other reason I will leave that. Best plan at the moment seems to be to draw both fields of a frame on top of each other because they are identical. That helps a lot because instead of drawing 625 lines from top to bottom I just need to draw 312.5 lines from top to bottom then start at the top again. I will be away for a few days helping to decorate the hall for the volunteer firebrigade annual dance.
Interlace or Progressive...
I'm on an Sony 1271 Crt projector 50 Hz with a 3.2 x 2.50 (1.33)interlaced mode, if you are under 5 meters near the screen you can see the big lines... The interest of a scaler is to make an interpolation beetween line 1 and line 3, because the line 2 and 4 are on a next image, so if i'm right you can't just reorder the sequence of lines.
There is several interpolartion modes explain in
deinterlace.sourceforge.net/downloads.htm
There is no problem to see TV with a scaler, you just need a video input board.
I think there is some questions :
Do you want to use DVD with more lines ?
compatibility 16/9 and 3/4 Ratio ?
Composite, RVB, or SDI inputs ?
Vertical and Horizontal Frequencies ?
Vertical and Horizontal Synchro mode ?
Remote control ?
I still think a PC will help, doing all this tasks...
e.g 50 Hz 516 lines interlaced input -> 75 Hz progressive 700 lines output.
Or we can buy a Faroudjia ;-)
Pa
I'm on an Sony 1271 Crt projector 50 Hz with a 3.2 x 2.50 (1.33)interlaced mode, if you are under 5 meters near the screen you can see the big lines... The interest of a scaler is to make an interpolation beetween line 1 and line 3, because the line 2 and 4 are on a next image, so if i'm right you can't just reorder the sequence of lines.
There is several interpolartion modes explain in
deinterlace.sourceforge.net/downloads.htm
There is no problem to see TV with a scaler, you just need a video input board.
I think there is some questions :
Do you want to use DVD with more lines ?
compatibility 16/9 and 3/4 Ratio ?
Composite, RVB, or SDI inputs ?
Vertical and Horizontal Frequencies ?
Vertical and Horizontal Synchro mode ?
Remote control ?
I still think a PC will help, doing all this tasks...
e.g 50 Hz 516 lines interlaced input -> 75 Hz progressive 700 lines output.
Or we can buy a Faroudjia ;-)
Pa
Hi back again. We had a very succesful dance. Raised some money for the volunteer firebrigade. 10 dollars for a dance per person with a live band, good supper and terrific atmosphere hard to beat. Today I planned on seeing some raster lines. Using the 8 facet horizontal polygon would have required a revolving device to separate the 8 lines coming from the polygon otherwise I would just see 8 lines on top of each other. To avoid using a vertical polygon I used an alternative. By mounting a small mirror 1/2 inch x 3/4 inch on top of the horizontal polygon I could arrange some mirrors on a radius around the polygon and by tilting each mirror slightly I could get lines. Bought a thin mirror from the $2 shop and a glass cutter. Cut the mirror into rectangles 2 inch x 1 inch. Cut some wood pieces inch and 3/4 wide x inch and a half long x 1/2 an inch thick. 1/4 inch in from one end cut a slot with my table saw 1/4 inch deep. At the other end drilled a hole to take a number 8 pk screw. Mounted each mirror in the saw cut on each piece of wood using folded paper to make a tight fit. Arranged a wooden surface level with the single mirror on top of the polygon and arranged the mirrors in a radius centered on the polygon motor shaft. Switched on the 5 mw laser diode which you remember is now modulated with horizontal sync pulses and did some lining up of the mirrors. End result was 8 horizontal raster lines with various spacings between lines. By adjusting the pk screw in the mirror mounts I could adjust the mirrors to give about a 1/16 inch spacing between lines. I was very pleased with the result. The sync pulses had to be lined up vertically by moving the mirrors but I got an 8 line raster. There were a couple of problems. I could not cut the glass exactly so some lines were longer than others. The mirror was only revolving at 1500 rpm should have been 3000 rpm (50 fields per second x 60 seconds=3000 rpm) I ran it slower for safety reasons. Will have to improve the mirror mount otherwise it might fly off. By running at 1500 rpm instead of 3000 rpm I got 2 sync pulses per raster line. Should be only one. Will be only one at 3000 rpm.
There was an unexpected bonus. With one raster line it was quite dim. 8 raster lines was quite a bit brighter as each raster line contributed to the impression of brightness. That will not happen to the same extent when I apply video modulation to the laser diode. Correction. In my post above I said the A and B fields of a frame are identical. They are not identical, they are very similar.
Next step is to secure the mirror on top of the polygon so I can go up to 3000 rpm. Put a 10 turn pot in my signal generator so it becomes easier to make the sync pulses stand still and maybe cut some more accurate mirrors.
There was an unexpected bonus. With one raster line it was quite dim. 8 raster lines was quite a bit brighter as each raster line contributed to the impression of brightness. That will not happen to the same extent when I apply video modulation to the laser diode. Correction. In my post above I said the A and B fields of a frame are identical. They are not identical, they are very similar.
Next step is to secure the mirror on top of the polygon so I can go up to 3000 rpm. Put a 10 turn pot in my signal generator so it becomes easier to make the sync pulses stand still and maybe cut some more accurate mirrors.
Put a second 10 turn potentiometer in my signal generator driving the polygon mirror and it works good. Now have a 10 turn 10k coarse speed adjust and a 10 turn 2k fine speed adjust. Plenty of control. Can make the sync pulses stand still for long periods of time even though the generator is not very flash. Secured the single sided mirror on top of the polygon and increased motor speed to 3000 rpm. Got one sync pulse per line. Tried to cut more accurate mirrors. All mirrors have to be pretty close to the same width otherwise the raster lines are shorter or longer than they should be. Have to leave a small adjustment gap about 0.005 inch between mirrors to accomodate shorter or longer mirrors which hopefully will be where the retrace takes place and the gap will not reduce picture information. Have to buy the mirrors, too hard to cut square and of the same width. At the moment I am using ordinary mirror glass.
To date I have 8 raster lines of roughly similar widths about 2.5 inches on a screen 2 feet from the polygon. Everything is lined up with books pieces of wood and paper shims and is hard to work on. Make one adjustment and the slightest touch puts other mirrors out of alignment. Will look at a solid mirror platform soon. It is very satisfying to see the polygon revolving and a few raster lines on the screen.
To date I have 8 raster lines of roughly similar widths about 2.5 inches on a screen 2 feet from the polygon. Everything is lined up with books pieces of wood and paper shims and is hard to work on. Make one adjustment and the slightest touch puts other mirrors out of alignment. Will look at a solid mirror platform soon. It is very satisfying to see the polygon revolving and a few raster lines on the screen.
Greetings. I have now made a good solid mirror table from some heavy 1 inch formica covered wood. Sealed the edges and drilled 3 undersize holes for some 1/4 inch fine pitch bolts and forced them into the wood and the bolts cut a thread in the wood. Little bit of candle grease on the threads. Now I can adjust the bolts easy for setting the mirror table level with the polygon. Plan to make a new modulator. I have been using a 330 ohm 10 watt resistor from a 25-30 volt regulated supply with a milli amp meter feeding the laser with constant (adjustable) current. The 5 mw laser works from 50 milli amp to 90 milli amp. Other laser diodes may be different. Do not rely on guessing the maximum current. Laser diodes will stop working if the current exceeds the maximum even for a very brief time. Modulation was by putting a transistor in between the laser diode and ground. Worked ok and the laser could never get too much current. Changing that to putting the modulation transistor across the laser diode so when the transistor is off the laser gets all the current and when the transistor is fully on the laser gets no current. Its called current stealing and is one of the safer ways of powering a laser diode. The advantage of the change is I can set the lasing threshold easier. I will also replace the 330 ohm resisitor with 2 resistors and a 12 volt zeener diode from the midpoint to ground. That is in case my regulated supply fails and puts out too much voltage. The first modulation will be the usual horizontal sync pulses I have been doing for the last several days to identify tv lines and a second modulation of gradually lowering the laser current over 10 tv lines from full to minimum . This is to see if I am looking at 10 consecutive tv lines rather than several lines on top of each other.
Greetings. Have installed the new laser diode modulator as described in the previous post and it works ok. It is a 2n2102 NPN transistor across the 5 mw laser diode and biased so just not conducting. In that condition the laser diode has 90 ma of current and is producing a laser beam. When I apply sync pulses to the modulation transistor it turns on, takes most of the current from the laser and this shows as a period of no laser light. The light on a screen from the single sided mirror on top of the polygon thus shows up as a red line with a black portion equivalent to the sync pulse. As mentioned in the last post I wanted to verify I was seeing individual raster lines not several lines on top of each other. My tv signal generator puts out video plus sync pulses with a selection of patterns. The easiest pattern to identify is a black screen with a single horizontal line halfway down. Using this I saw very dim raster lines until the horizontal line came into view and that one was bright just as it should be.
So far I have used the following equipment
0-12v power supply for polygon motor
0-30v power supply for laser
polygon motor with 8 facet mirror and home made single sided mirror mounted on motor shaft.
8 small mirrors fitted into wooden mounting blocks
Sturdy adjustable mirror table.
Small white screen (a4 envelope)
5 Mw red laser diode
single transistor modulator.
Squarewave signal generator to drive polygon motor
TV signal generator for sync pulses and video mudulation
Best results so far
8 vertical raster lines of poor quality with discernable modulation.
The 5 mw red laser diode gives visible raster lines in a darkened room. The quality from my laser diode is not very good but it can be modulated easily and beam quality may be able to be improved perhaps with a short lenght of fibre optic and some type of lens. The mirrors are extremely touchy to adjust.
In my experimenting I have found one very important fact. The light from a laser beam does not reduce in proportion to the number of raster lines. I presently have on the walls of my workshop 300 or so tv lines (one tv field) one after another and identified by a horizontal sync pulse and each line is about half the brightness of the original laser beam. All the lines are the same brightness and they are definitly not original light/300. If that were the case I probably would not see them at all but I can see them even with some ambient. Some lines have modulation which is clear and discernable so the lines are individual, not several lines on top of each other. That result is even more interesting because the lines on the wall are reflected from a rotating single sided household type mirror on the polygon so the refresh rate is only 50 percent.
So far, in this low cost small scale test of a laser projector I am happy with results.
So far I have used the following equipment
0-12v power supply for polygon motor
0-30v power supply for laser
polygon motor with 8 facet mirror and home made single sided mirror mounted on motor shaft.
8 small mirrors fitted into wooden mounting blocks
Sturdy adjustable mirror table.
Small white screen (a4 envelope)
5 Mw red laser diode
single transistor modulator.
Squarewave signal generator to drive polygon motor
TV signal generator for sync pulses and video mudulation
Best results so far
8 vertical raster lines of poor quality with discernable modulation.
The 5 mw red laser diode gives visible raster lines in a darkened room. The quality from my laser diode is not very good but it can be modulated easily and beam quality may be able to be improved perhaps with a short lenght of fibre optic and some type of lens. The mirrors are extremely touchy to adjust.
In my experimenting I have found one very important fact. The light from a laser beam does not reduce in proportion to the number of raster lines. I presently have on the walls of my workshop 300 or so tv lines (one tv field) one after another and identified by a horizontal sync pulse and each line is about half the brightness of the original laser beam. All the lines are the same brightness and they are definitly not original light/300. If that were the case I probably would not see them at all but I can see them even with some ambient. Some lines have modulation which is clear and discernable so the lines are individual, not several lines on top of each other. That result is even more interesting because the lines on the wall are reflected from a rotating single sided household type mirror on the polygon so the refresh rate is only 50 percent.
So far, in this low cost small scale test of a laser projector I am happy with results.
Hi there. Today I wanted to confirm the speed of the polygon motor by reflecting the laser beam off the polygon into a detector and counting the pulses. Set up a photodiode in front of the 8 factory mirrors on the polygon. Ran the motor at what I thought was 1500 rpm. Obtained a reading of 200 pulses per second from my frequency counter. 200 puses per second times 60 equeals 12000 and divided by 8 because there are 8 mirrors on the polygon gives 1500 RPM. Did the same setup on the DIY single sided mirror which gave 25 pulses per second times 60 equeals 1500 RPM. This confirmed that when I give the drive electronics for the polygon motor a squarewave at 1500 per second from my signal generator I get 1500 RPM from the motor. I thought that was good thinking by the polygon manufacturer to give a direct 1:1 correlation between drive in Hz and motor speed in RPM. Panasonic motor type MASQ8B24RM1 fitted with 8 sided mirror polygon. Motor runs up to 2000 RPM on 12 vdc Higher speed needs 24 vdc. The motor is rated at 24 vdc. Squarewave input 10 v peak to peak. One side of motor electronics input is ground. A 555 ic should run these motors ok.
picture?
I'm having trouble understanding what all the mirrors are doing - specifically how do you get one horizontal line to be higher or lower than another. would it be possible to post a picture somewhere?
I'm having trouble understanding what all the mirrors are doing - specifically how do you get one horizontal line to be higher or lower than another. would it be possible to post a picture somewhere?
Hi Evaas. You are not the only one having trouble with the mirrors. The reason for using mirrors is because an ordinary ball bearing polygon motor with a number of reflecting facets cannot run at the very high speeds necessary for television line scaning. You can buy high speed polygon units that will do the job but the price is outside my means. Some simple means therefore has to be found to assist the normal type of polygon one can buy from surplus shops or remove from laser printers. The early pioneers in mechanical television figured out many clever ways of using mirrors in line scaning systems. Many of these used a central polygon surrounded by a ring of mirrors. The idea being the laser or light source hits the polygon mirrors, is reflected out to the ring of mirrors and reflected back to the polygon mirrors and then on to the projection screen. This did two things. First the ring or part ring of mirrors allowed the polygon to run at a much reduced speed and second it usually reduced the final scan angle. Both these features can be useful in DIY laser projector.
Have a look at the following USA patents.
2149198
2139869
2070460
2163548
5148285
You probably cannot use these patents or any patent information for comercial use without discussion with the patent holder or their succesors. I am presently using a single sided mirror which I mounted on top of my polygon so as to investigate different aspects of laser projection and patent 2139869 fig 4 shows the setup except I am only using 8 mirrors. To answer your question my setup is as follows using 8 mirrors. Laser light goes to the single one sided mirror on the polygon, from the polygon to each of the 8 mirrors from the mirrors over the top of the polygon onto a screen. Arranging the 8 mirrors around the polygon I get 8 raster lines but their vertical position depends on how squarely I have mounted them. This is where the PK screw is used to slightly tip each of the 8 mirrors a little bit so the raster lines are under each other.
Its not hard to do except for making a single sided mirror that fits (securely) on top of the polygon. I made a mirror holder from a straight sided aluminium instrument knob which had a 6 mm hole and a securing grub screw. I cut a slot in the top of the knob with a hacksaw with 2 blades fitted. The slot was just a bit wider than small mirror I cut 1/2 inch x 3/4 inch high but packing the mirror with paper it pushed in very tight. The polygon mirror had a 3/16th securing plate held on with 3 screws. I removed the securing plate, refitted the screws with more washers and that gave me more motor shaft to attach my own single sided mirror. Tested to 3000 RPM but I felt 3000 RPM was not safe so presently the polygon runs at 1500 RPM. Everytime before using the polygon I test the mirror tightness and so far it is firm and well held. I have no means at present to post pictures but hope to sometime.
Evaas I have to tell you something. My little laser setup is already producing laser pictures in my workshop. Here's how. When I turn on the polygon and using the single sided mirror and the laser I get a ring of laser light around the walls of my workshop. Thats it, just an unbroken ring of laser light in a thin beam around the walls. However when I turn on the sync pulse generator that ring of light is broken up into short lines with gaps where the sync pulses are. By slowing or speeding up the polygon speed I can get these short lines to stand still. Instead of looking at an unbroken ring of light I am now looking at raster lines. When I turn on the modulator I can see the short lines with modulation. I have tv raster lines, they are modulated and the whole bunch of lines are standing still. Because the raster lines are sequential ie one followed by another in a horizontal ring around my workshop walls, the picture is hard to watch and, at the moment the quality is very poor. All I have to do is take each of those short lines, stack them on top of each other in a normal raster fashion and hey presto a picture. Hopefully that is where the mirrors come in.
Have a look at the following USA patents.
2149198
2139869
2070460
2163548
5148285
You probably cannot use these patents or any patent information for comercial use without discussion with the patent holder or their succesors. I am presently using a single sided mirror which I mounted on top of my polygon so as to investigate different aspects of laser projection and patent 2139869 fig 4 shows the setup except I am only using 8 mirrors. To answer your question my setup is as follows using 8 mirrors. Laser light goes to the single one sided mirror on the polygon, from the polygon to each of the 8 mirrors from the mirrors over the top of the polygon onto a screen. Arranging the 8 mirrors around the polygon I get 8 raster lines but their vertical position depends on how squarely I have mounted them. This is where the PK screw is used to slightly tip each of the 8 mirrors a little bit so the raster lines are under each other.
Its not hard to do except for making a single sided mirror that fits (securely) on top of the polygon. I made a mirror holder from a straight sided aluminium instrument knob which had a 6 mm hole and a securing grub screw. I cut a slot in the top of the knob with a hacksaw with 2 blades fitted. The slot was just a bit wider than small mirror I cut 1/2 inch x 3/4 inch high but packing the mirror with paper it pushed in very tight. The polygon mirror had a 3/16th securing plate held on with 3 screws. I removed the securing plate, refitted the screws with more washers and that gave me more motor shaft to attach my own single sided mirror. Tested to 3000 RPM but I felt 3000 RPM was not safe so presently the polygon runs at 1500 RPM. Everytime before using the polygon I test the mirror tightness and so far it is firm and well held. I have no means at present to post pictures but hope to sometime.
Evaas I have to tell you something. My little laser setup is already producing laser pictures in my workshop. Here's how. When I turn on the polygon and using the single sided mirror and the laser I get a ring of laser light around the walls of my workshop. Thats it, just an unbroken ring of laser light in a thin beam around the walls. However when I turn on the sync pulse generator that ring of light is broken up into short lines with gaps where the sync pulses are. By slowing or speeding up the polygon speed I can get these short lines to stand still. Instead of looking at an unbroken ring of light I am now looking at raster lines. When I turn on the modulator I can see the short lines with modulation. I have tv raster lines, they are modulated and the whole bunch of lines are standing still. Because the raster lines are sequential ie one followed by another in a horizontal ring around my workshop walls, the picture is hard to watch and, at the moment the quality is very poor. All I have to do is take each of those short lines, stack them on top of each other in a normal raster fashion and hey presto a picture. Hopefully that is where the mirrors come in.
Scanner
I have began construction of my system, while I am not going to use a laser nor am I going to use the scanning sytem you are mine is still mechanical. It uses two mirrors one perfomes horizontal scanning while the other produces vertical scanning. The 2 mirros are mounted on springs and one side has a small peice of metal atached so the electromacgnet can move the mirror at the correct horizontal or vertical frequecny. I have set it up and has also been able to produce a raster line on my wall. Does anyone know how to construct a light modulator of high brightness light sources such as those used in DLP projectors?
I have began construction of my system, while I am not going to use a laser nor am I going to use the scanning sytem you are mine is still mechanical. It uses two mirrors one perfomes horizontal scanning while the other produces vertical scanning. The 2 mirros are mounted on springs and one side has a small peice of metal atached so the electromacgnet can move the mirror at the correct horizontal or vertical frequecny. I have set it up and has also been able to produce a raster line on my wall. Does anyone know how to construct a light modulator of high brightness light sources such as those used in DLP projectors?
Fiat1. DLP projectors use an IC with a lot of extremely small mirrors. It is an invention of Texas Instruments. The very small mirrors can move extremely rapidly to give the same effect as modulating a beam of light but its not something you can build at home because the mirrors are microscopic in size. They are manufactured as part of the IC. I have only ever seen one place in America offering DLP IC's and these had the comments no data available, condition unknown. You could use a liquid crystal panel to modulate a beam of light but I dont know any details. Have not looked at modulation apart from modulating a 5 mw red laser diode.
Hello
My system does not use a DLP chip in it, instead it uses one whole mirror to carry out the scanning of the image. I did not invent it or anything just mixed some old and new technology together.
My system does not use a DLP chip in it, instead it uses one whole mirror to carry out the scanning of the image. I did not invent it or anything just mixed some old and new technology together.
Hi there. Been trying to improve my simple laser modulator with not much success. I need this working correctly to identify the sequence of raster lines. Will stop for Christmas and have a break after and may purchase a decent modulator chip from someone.
Cheers
Cheers
Hello remp,
have a look on:
http://www.gebrauchtlaser.de/gebrauch/d2-z.htm
They sell polygon-mirrors with 10-15-18 facettes, also acousto-optic modulators for very cheap second-hand price.
A couple of years ago i did the same experiments, but the main problem will be:
1.How to reach the hor. deflection frequency of 15,625 khz?
2.How to get horizontal lines jitterfree?
In commercial solutions the videosignal will be buffered, so that when laser reach a new facet of polygon then the videodata will be read out just in time.(laserTV,Laser Display...)
At least my researches focused at a one row led array, which was multiplexed with the pixel clock frequency. Vertical deflection i did with a loudspeaker-scanner. Placing the vert. scanner in face of the led row ,i could see the videoimage in the vert. scanner mirror! Now if the leds where laserdiodes there would be a real projectable image. My system had one 40 led pixel row. That is, of course poor resolution. But this could be easily improoved by taking more pixelleds.
The pixelclock was easily realised by PLL (hor. freq. X Number of leds).The whole arrangement needs very low power consumance, because the leds are driven one by one, like a running light.
someday if there are laserlike leds there would be chance to realize a cheap led display.
Greetings
xblocker
have a look on:
http://www.gebrauchtlaser.de/gebrauch/d2-z.htm
They sell polygon-mirrors with 10-15-18 facettes, also acousto-optic modulators for very cheap second-hand price.
A couple of years ago i did the same experiments, but the main problem will be:
1.How to reach the hor. deflection frequency of 15,625 khz?
2.How to get horizontal lines jitterfree?
In commercial solutions the videosignal will be buffered, so that when laser reach a new facet of polygon then the videodata will be read out just in time.(laserTV,Laser Display...)
At least my researches focused at a one row led array, which was multiplexed with the pixel clock frequency. Vertical deflection i did with a loudspeaker-scanner. Placing the vert. scanner in face of the led row ,i could see the videoimage in the vert. scanner mirror! Now if the leds where laserdiodes there would be a real projectable image. My system had one 40 led pixel row. That is, of course poor resolution. But this could be easily improoved by taking more pixelleds.
The pixelclock was easily realised by PLL (hor. freq. X Number of leds).The whole arrangement needs very low power consumance, because the leds are driven one by one, like a running light.
someday if there are laserlike leds there would be chance to realize a cheap led display.
Greetings
xblocker
Greetings,
Hi Xblocker
Thanks for info. Looks like good stuff there. Is that Euro dollars or German currency. How much is 8.900,-- in U.S. dollars approx. Just need a guide to see how prices are.
Your one sounds interesting. Specially the frame scan using a loudspeaker. How did you get a line of video into 40 leds.
You ask how to scan at 15625. (Pal TV not NTSC)
15625 lines per second is 937500 lines per minute
With an 8 mirror polygon you need 117,187.5 revs per minute
With a 25 mirror polygon 37,500 revs per minute
Very high speed, and expensive equipment if bought new. I don't have money for that. Using an ex printer polygon as described in previous post 8 mirrors maximum speed 10,000 RPM. Early tv pioneers like Ernest Traub and other gentlemen showed ways of using low speed polygons with fixed mirrors to get high deflection speeds. Sony did too. The end of facet problem I hope happens in horizontal retrace time. Hitachi printer model DIPS 6000 polygon runs at 42000 RPM which could be very useful.
Progress so far is good. To investigate laser scanning in detail, I am using a single sided mirror on top of the polygon reflecting a laser beam around the 4 walls of workshop. Without modulation just a line. With H sync modulation you can see a gap where each line starts. Instead of using 625 lines which is one frame I am looking for 312 lines which is one field (2 fields per frame). because 312 lines fit into a 360 degree circle. I should see 312 gaps. At polygon speed of 1500 rpm I see about 200 lines. That means I have to run the polygon slower probably 1200 rpm to see 312 lines. Each line should be about an inch at 8 foot radius. Using 2 10 turn potentiometers in the audio squarewave generator driving the polygon I can get such fine speed control the lines stand still for 5-10 minutes at a time without any synchronising. At small scale no sign of any line jitter at all. Steady as a rock. Thats pretty good for a mechanical system. I will worry about proper synchronizing later.
When I have got 312 lines occupying a full circle and stationary with modulation to identify lines/frame pulses I can say there is one tv field.
One tv field on the walls is better than none but there are big problems ahead.
Have to take those 312 lines and put them in a normal raster format. Thats the key point because the rest is not too difficult. This is where Mr Traub and his clever use of mirrors comes in.
I think I need 39 mirrors to go with my 8 mirror polygon to display one 312.5 line field in one 50th of a second at 3000 rpm.
Have to improve a diode laser to a thin good beam. They say you need 3 small lens or fibre optic for that. Have seen some on the net and might look into that.
How to get high speed laser diode modulator. Have searched the web very very little available. Plenty for 10 gigahertz digital but not for amplitude modulated video. Probably no call for it. I need a circuit or IC that can AM modulate a low power laser diode up to 10 mhz.
At the end of that a very small very faint red picture of sorts.
If it works just need to display the A and B fields of a frame, add more powerfull light and a way to combine 3 light beams into one.
Need to split composite video into red/green/blue drives and find a cheap powerful source of red green and blue light and 3 modulators.
My plan is like so
January modulator
February improve laser beam
March bring in mirrors and frame scanner if that fails
April look at other deflection means
Best wishes for Christmas and new year.
Hi Xblocker
Thanks for info. Looks like good stuff there. Is that Euro dollars or German currency. How much is 8.900,-- in U.S. dollars approx. Just need a guide to see how prices are.
Your one sounds interesting. Specially the frame scan using a loudspeaker. How did you get a line of video into 40 leds.
You ask how to scan at 15625. (Pal TV not NTSC)
15625 lines per second is 937500 lines per minute
With an 8 mirror polygon you need 117,187.5 revs per minute
With a 25 mirror polygon 37,500 revs per minute
Very high speed, and expensive equipment if bought new. I don't have money for that. Using an ex printer polygon as described in previous post 8 mirrors maximum speed 10,000 RPM. Early tv pioneers like Ernest Traub and other gentlemen showed ways of using low speed polygons with fixed mirrors to get high deflection speeds. Sony did too. The end of facet problem I hope happens in horizontal retrace time. Hitachi printer model DIPS 6000 polygon runs at 42000 RPM which could be very useful.
Progress so far is good. To investigate laser scanning in detail, I am using a single sided mirror on top of the polygon reflecting a laser beam around the 4 walls of workshop. Without modulation just a line. With H sync modulation you can see a gap where each line starts. Instead of using 625 lines which is one frame I am looking for 312 lines which is one field (2 fields per frame). because 312 lines fit into a 360 degree circle. I should see 312 gaps. At polygon speed of 1500 rpm I see about 200 lines. That means I have to run the polygon slower probably 1200 rpm to see 312 lines. Each line should be about an inch at 8 foot radius. Using 2 10 turn potentiometers in the audio squarewave generator driving the polygon I can get such fine speed control the lines stand still for 5-10 minutes at a time without any synchronising. At small scale no sign of any line jitter at all. Steady as a rock. Thats pretty good for a mechanical system. I will worry about proper synchronizing later.
When I have got 312 lines occupying a full circle and stationary with modulation to identify lines/frame pulses I can say there is one tv field.
One tv field on the walls is better than none but there are big problems ahead.
Have to take those 312 lines and put them in a normal raster format. Thats the key point because the rest is not too difficult. This is where Mr Traub and his clever use of mirrors comes in.
I think I need 39 mirrors to go with my 8 mirror polygon to display one 312.5 line field in one 50th of a second at 3000 rpm.
Have to improve a diode laser to a thin good beam. They say you need 3 small lens or fibre optic for that. Have seen some on the net and might look into that.
How to get high speed laser diode modulator. Have searched the web very very little available. Plenty for 10 gigahertz digital but not for amplitude modulated video. Probably no call for it. I need a circuit or IC that can AM modulate a low power laser diode up to 10 mhz.
At the end of that a very small very faint red picture of sorts.
If it works just need to display the A and B fields of a frame, add more powerfull light and a way to combine 3 light beams into one.
Need to split composite video into red/green/blue drives and find a cheap powerful source of red green and blue light and 3 modulators.
My plan is like so
January modulator
February improve laser beam
March bring in mirrors and frame scanner if that fails
April look at other deflection means
Best wishes for Christmas and new year.
Greetings
Correction to above. The 312 lines I am looking for are in a half circle not a full circle.
Correction to above. The 312 lines I am looking for are in a half circle not a full circle.
I read the NG alt.lasers, and this might be a good resource for you. They frequently discuss laser projection. I have thought about trying it myself, but havn't had the time or money. As far as colors go red green and blue do exist. Be prepared to pay thousands for blue though. A whitelight Argon/Krypton laser is available. They can reach several WATTS of power.
The best resouce of all is Sam Goldwasser's website
http://www.laserfaq.com
Darrell Harmon
The best resouce of all is Sam Goldwasser's website
http://www.laserfaq.com
Darrell Harmon
Hello Richard,
First of all, the prices you asked are DM. In 2002 we get EURO.Thats 1/2 of DM.
It's crazy, but i tried the same with this mirror drum thing without knowing of Mahaly Traub. I called it the light-circus arena. I constructed a 360 degree circleboard with one open entrance(circus!) and placed alot of little mirrors along the inside Just for experiments. In the center a doublesided rotationmirror. The idea was to shoot the laserbeam onto rotationmirror then onto stationary mirror for the videoline and the same way back slightly beside the laserdiode. One side of the rot.mirror should do the first frame the other side the second. The light entrance and exit should be she blackshoulder of the videosignal. But...
First of all there are immense mechanical ploblems of precision and adjustments. How to fasten all the mirrors? Then what to do if the rotationmirror turns into 180 or 0 degree position? Another problem ,the relation of the number of staionary mirrors and the deflection angle. The more mirrors the smaller the deflection because of geometric optics. It's true, a polygon can reduce the number of mirrors. But the more stationary mirrors the smaller the deflection because of geometric optics
I also tried to beam from the top of the arrangement onto the axis of the mirrorcircle. Changed the the rotationmirror into a 45° position so that there was a continous beam around my mirror arena. But then the reflected beamlines naturally did the same rotation as the rotation mirror. Unusable. Also i wasn't able to adjust stat. mirrors properly 'cause i could't fasten them precisely. I also killed the laserdiode and gave up.
Turned into that Led project. Sometimes it's usefull to simplify things to get the clue of something. The idea is simple. you have to bring the light of video into roomcoordinates. If somebody had a very fast hand, he could move a led and draw the video 15625 times a second from left to right, slightly shifted to get the video raster.
The same can be done by letting do many leds this work. I started with 10 leds a row and gave each led the video information of 15625/10. That means 1 led has 1/(10*15625)sec time to show 1/10 of 1 videoline. (156,25Khz=pixelclock). With a PLL multiplier it's easy to do that. Now if every led gets its information each after the other you have at least a complete videoline. This can be done with a simple multiplexer.
next I pushed up with 20 and then with 40 leds. Now if you enlarge this you can go up to 800 horizontal resolution.
The vertical scanning i did with a little speaker, ripped of the black paper, sticked a small mirror on a small hinge. One side i fixed at the chassis the other at the speaker's memban with a piece of earstick.(very light). Generated a sawtooth from vertical sync linked to a simple audio amp, and then to the speaker. The vertical resolution was nearly perfect. The videoimage (mine was green) could be viewed in the mirror of the speaker. Overscan could be corrigated by forming of sawtooth, like in CRT-displays
With this vertical scanner it's also possible to deflect laserbeam coming from hor. polygon.
A commercial deflection system is also described at:
http://www.schneider-ag.de/
They use a 2000 rotation/sec going up to 48khz hor.-frequency for use also with vga standards. For green and blue they use frequency doublers of infrared.
I hope all this is understandable, because i don't know all technical terms in english.
Greetings xblocker
First of all, the prices you asked are DM. In 2002 we get EURO.Thats 1/2 of DM.
It's crazy, but i tried the same with this mirror drum thing without knowing of Mahaly Traub. I called it the light-circus arena. I constructed a 360 degree circleboard with one open entrance(circus!) and placed alot of little mirrors along the inside Just for experiments. In the center a doublesided rotationmirror. The idea was to shoot the laserbeam onto rotationmirror then onto stationary mirror for the videoline and the same way back slightly beside the laserdiode. One side of the rot.mirror should do the first frame the other side the second. The light entrance and exit should be she blackshoulder of the videosignal. But...
First of all there are immense mechanical ploblems of precision and adjustments. How to fasten all the mirrors? Then what to do if the rotationmirror turns into 180 or 0 degree position? Another problem ,the relation of the number of staionary mirrors and the deflection angle. The more mirrors the smaller the deflection because of geometric optics. It's true, a polygon can reduce the number of mirrors. But the more stationary mirrors the smaller the deflection because of geometric optics
I also tried to beam from the top of the arrangement onto the axis of the mirrorcircle. Changed the the rotationmirror into a 45° position so that there was a continous beam around my mirror arena. But then the reflected beamlines naturally did the same rotation as the rotation mirror. Unusable. Also i wasn't able to adjust stat. mirrors properly 'cause i could't fasten them precisely. I also killed the laserdiode and gave up.
Turned into that Led project. Sometimes it's usefull to simplify things to get the clue of something. The idea is simple. you have to bring the light of video into roomcoordinates. If somebody had a very fast hand, he could move a led and draw the video 15625 times a second from left to right, slightly shifted to get the video raster.
The same can be done by letting do many leds this work. I started with 10 leds a row and gave each led the video information of 15625/10. That means 1 led has 1/(10*15625)sec time to show 1/10 of 1 videoline. (156,25Khz=pixelclock). With a PLL multiplier it's easy to do that. Now if every led gets its information each after the other you have at least a complete videoline. This can be done with a simple multiplexer.
next I pushed up with 20 and then with 40 leds. Now if you enlarge this you can go up to 800 horizontal resolution.
The vertical scanning i did with a little speaker, ripped of the black paper, sticked a small mirror on a small hinge. One side i fixed at the chassis the other at the speaker's memban with a piece of earstick.(very light). Generated a sawtooth from vertical sync linked to a simple audio amp, and then to the speaker. The vertical resolution was nearly perfect. The videoimage (mine was green) could be viewed in the mirror of the speaker. Overscan could be corrigated by forming of sawtooth, like in CRT-displays
With this vertical scanner it's also possible to deflect laserbeam coming from hor. polygon.
A commercial deflection system is also described at:
http://www.schneider-ag.de/
They use a 2000 rotation/sec going up to 48khz hor.-frequency for use also with vga standards. For green and blue they use frequency doublers of infrared.
I hope all this is understandable, because i don't know all technical terms in english.
Greetings xblocker
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