| Designs |
updated Monday, August 14, 2000
On this page we present system designs for use with the Cybermaxx LCD, test results from the designs, miscellaneous information relevant to system designs, and information on electronic devices that may be of use.
Our system designs
Test data from our designs
Cybermaxx design resources
Other design resources and information
Useful devices and software
Kristian's Design
Kristian has built a board (detailed under 'PC Boards' on this web site), and kindly provided me with a copy of the PC board itself, which, with Julie Porter's help and advice, I've built my own version of in spring 1999.
The design is based on the Panasonic PV-D705 camcorder schematic, copied from that model's repair manual.
I have designed RGB signal conditioner circuitry, and made a slight modification to the voltage divider for the LCD's Vcom (aka LCCOM), to prepare the board for testing. The RGB signal conditioner provides a switched inverter that keeps the output RGB from averaging a nonzero net value over time, followed by a summing amplifier that gives the RGB output its required 7-volt offset above system ground. The switched inverter takes the HT output from the MN83803Ax, and corresponds to the Frame Rate Pulse (FRP) input to the Sharp IR3y05(y). The schematic for the signal conditioner is preliminary, but should give a good idea of how to put one together, when viewed alongside National Semiconductor's data sheets for the Comlinear CLC430 and other I.C.s it uses.
When I finish the RGB signal conditioner construction (a matter of ordering the resistors and getting home from vacation to finish it), I will test the board and post results here. Initially I will use the Nuts & Volts video pattern generator to supply video to this circuit.
A Fully Integrated Design
Our fully integrated design improves on the functionality of Kristian's design by providing complete NTSC-to-RGB conversion on one board with the LCD driver, allowing the system to be plugged into a standard NTSC video source such as a VCR or video camera. The design makes use of the Sharp IR3y05 video processing chip to provide all the treatment of NTSC composite video that is needed to make the LCD display a TV picture. This design can be readily modified to display computer RGB such as suggested by Tom Cumming, since the Sharp chip can also perform this function (having RGB inputs as well).
Revision 'L' of our design has almost all of the mistakes taken out of it, so it's available for download. Where there are mistakes, we note them in a separate errata page. Check it out on our pc boards page. The design is in ExpressPCB format, and is ready to be manufactured (we've made five of them). All you need to view it is to download the freeware ExpressPCB CAD program. Revision 'M,' a more mistake-free design, is available on this site as well. It has not been manufactured or tested yet.
Tom Cumming's Program For Developing a Computer RGB Display System For the Cybermaxx Surplus LCD
Tom Cumming of ThinkThink weighs in with his outline of a development plan . His idea looks pretty sound. Should availability of the MN83803AK / AL become a problem, it will become the best idea, I think. Furthermore, for those of us who are interested in ICs with a larger footprint that may be easier to solder to / socket, perhaps the logic design of a successful Xilinx or Altera FPGA -based device could serve as a model for another FPGA -based device using Motorola FPGAs (for some models of which there is a freeware development system for the IBM PC compatible, and PLCC chips).
Nate Caine's Verbal Description of the LCD's Timing Control Signals and Registers
Also here is an excerpt from a communication from electrical engineer Nate Caine , explaining the working of the LCD timing circuitry verbally. This supplements his thorough work, presented partly in graphic form, at Halted Specialties, Inc .
Click "timing" to read the excerpt.
Marc Cygnus's LCD Video Test Board
Virtual Reality software pioneer Marc Cygnus, formerly of VictorMaxx, has a board that operates LCDs, using it to test the ones he has. Here are two pictures of it: (1) the whole board , and (2) a close-up of the LCD attached to it, working. The driver board has the designation 'BE07K030' silkscreened onto it. The LCDs have a different pin count than ours, and appear to be the same kind that are used in the Forte VFX-1 VR helmet's video system.
It has a 64-pin chip on it (note that the Cybermaxx 180k Daniel Heckenberg took apart has a 68-pin QFP device on it, perhaps with the same function (notice their positions on the boards). The device Marc's board has carries the designation x57246A on it. Marc informs me, as others have suggested, that the Cybermaxx 180k never used the MN83803AL, using a Xilinx FPGA instead, for its video timings. (An (early?) manufacturer's parts lists for the Cybermaxx 180k included the MN83803AL)
Sync and Test Pattern Generator
Julie S. Porter is working on a sync and pattern generator for use with the LCDs, as well as a video signal processor based on the MC44011.
Electronic Information Online's LCD Expert
Rich Diehl presents much useful information on LCDs at Electronic Information Online . His work with EIO.com's 6" LCDs is very instructive (EIO has them for $99).
In fact, EIO.com has a plethora of resources and links that will interest the electronics hobbyist, some of which may prove applicable to the present work. Highly recommended!
A very good deal on some 4" LCD modules can be had at Bill and Jack's Robot and Video Page (http://www.angelfire.com/pa/videoandrobots/index.html) . Like EIO, they also have CCD panels for sale.
The General Reality Company sells virtual reality peripherals for industrial training, entertainment, and presentation applications, for which they've won a 'Technology of the Year' award. Check out their News page to find out about their innovations.
Useful Electronic Parts
IR3y05y video processing chip
Designed specially for LCD-based color electronic viewfinders, this chip can take either NTSC or an RGB input, with all video decoding facilities provided for on the chip. Especially useful for LCDs is a nonlinear gamma correction scheme. Simple external controls are needed to get the chip working, but since this is a video system, there are quite a few of them, adding up to quite a few external passive components.
(see the schematics page, the parts-sources page , and Nate Caine's discussion for more information on this chip.
Harris/Intersil CD22402
Video sync generator chip. Fairly primitive by today's standards , but easy to use. NTSC & PAL modes with useful features like a cathode blanking interval output. A big plus is that it is genlockable, meaning that it can be put in synchrony with another video source, such as a video camera.
LM1881 video sync separator.
Very useful for NTSC applications of the LCD, it does as its description says. (Remember, the MCL0712A03 is designed for NTSC operation) The MN83803AK and -AL need an NTSC sync to coordinate them with the RGB information to be scanned into the LCD matrix. This chip gets that sync.
74ACT715 (aka LM1882) master sync generator.
This chip's default mask programming puts it into NTSC timing. The 74ACT715-R (aka LM1882R) is mask-programmed to default to the clock-enabled state, making it very easy to start up into NTSC timing. The chip can be reprogrammed on the fly (best done during the vertical blank interval) for genlocking, but functions best as master generator. Good to use if there is no NTSC composite video signal for the LM1881 to extract a sync from.
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