Reply by July 14, 20142014-07-14
On Thu, 10 Jul 2014 12:16:28 -0700, Don Y <this@is.not.me.com> wrote:

>Hi, > >Anyone know how the drive to an LCD panel works? Specifically, >how one can force the display to appear "all white" or "all >black" WITHOUT relying on the electronics already present >in the monitor? > >E.g., imagine having *just* the LCD panel and being able to >operate it as a "light gate" (full on, full off). > >Thx!
Something like the dimmable windows on Boeing 787 Dreamliner ?
Reply by Don Y July 13, 20142014-07-13
Hi Tauno,

On 7/12/2014 1:04 PM, Tauno Voipio wrote:

>>>> But, I thought larger panels had some active components *in* (on) >>>> the glass to effectively treat the display as a storage device >>>> that is "refreshed" with new data, periodically (?) >>> >>> For monochrome panels, the usual chip was KS0083. It is a 80 bit >>> shift register with LCD output level shifters. >> >> This seems similar to the Hughes (?) devices I used ~1980 (though >> they were DIP40). IIRC, the output was "multivalued" -- not just >> a simple (2 level) translator -- to ensure DC stayed off the glass. >> >>> For a 320 by 240 display, there were 4 KS0083's for columns and >>> 3 chips for rows. The data was fed serially to the column chips, >>> with the rows clocked once for each full row. I used a refresh >>> rate of 14400 row/s, giving 60 frames/s. >> >> Yes, similar to the Hughes interface -- though I was driving a >> much smaller display (7x95). OTOH, a fair bit of overhead for >> a machine with a 2MB/s bus! >> >> But, how does this all relate to current technology? My understanding >> is that new panels are treated almost as a sort of write-only DRAM. >> The electrical interface serving to store a charge in each "accessed >> row's" column cell instead of just presenting an instantaneous >> voltage across each cell. > > Actually the output was 6 levels, to cater for the multiplexing and
My memory suggested 4 -- I have an image of a "staircase" waveform in my mind -- but I wouldn't put any money on that! :>
> DC avoidance. See the KS0083 datasheet, it is still available in > the Net.
I looked at it when you first mentioned it in the hope that it would have been the (Hughes?) chip that I used (it wasn't). And, I am too lazy to uncrate old project files just to locate the schematics for a 30+ year old design! :< So, is the electrical interface compatible with (dumb) multiplexed glass *and* the active matrix technology more commonly used today (e.g., in TV's, LCD monitors, etc.)?
Reply by Don Y July 13, 20142014-07-13
Hi Joseph,

On 7/11/2014 9:03 PM, josephkk wrote:
> On Thu, 10 Jul 2014 12:16:28 -0700, Don Y<this@is.not.me.com> wrote: > >> Anyone know how the drive to an LCD panel works? Specifically, >> how one can force the display to appear "all white" or "all >> black" WITHOUT relying on the electronics already present >> in the monitor? >> >> E.g., imagine having *just* the LCD panel and being able to >> operate it as a "light gate" (full on, full off). > > So get a LCD to do just that. Simple drive. > A small cell phone 320 by 240 color display requires thousands of > connections with complex driver ICs.
I didn't say I *wanted* to operate it as a light gate. Rather, I offered an example of the sort of information I was seeking. I have a novel approach to a client's problem and needed a better understanding of how *current* LCD technology works before proposing it as a solution. I don't want to suggest they have custom glass designed only to discover the concept won't work (there's a fair bit of development dollars at risk). Likewise, want to be able to argue effectively with them and, ultimately, the glass vendor about the approach I want to take.
> No, i do not know where to get them off the top of my head.
If the *concept* works, they will undoubtedly approach a volume manufacturer for the prototype -- probably with some guarantee of the manufacturing that will follow and conditions restricting the sale of any similar products to others (until patent clears) as that manufacturer will have the only experience in the "solution". I've seen the same approach used in other situations where a particular technology doesn't "quite" exist -- yet. (and, when the "customer" didn't want to have to bankroll the development only to watch others compete with *them*!)
Reply by July 12, 20142014-07-12
On Sat, 12 Jul 2014 22:08:20 -0400, "Maynard A. Philbrook Jr."
<jamie_ka1lpa@charter.net> wrote:

>In article <q863s9lns5bj03kpjvqlk39sio7f9esq7g@4ax.com>, krw@attt.bizz >says... >> >> On Sat, 12 Jul 2014 10:33:07 -0700, Don Y <this@is.not.me.com> wrote: >> >> >On 7/12/2014 10:02 AM, edward.ming.lee@gmail.com wrote: >> >> >> >>> I want to know what the *glass* sees! >> >> >> >> Which glass? It probably depends on the manufacturer. As you and >> >> others pointed out, there are many ways of driving LCD/LED screens. >> >> They have dedicated controller for the specific panel technology and >> >> it is unlikely that you can use (or even get) the glass without their >> >> controller. >> > >> >FORGET *GETTING* THE GLASS! >> > >> >Does the (un)availability of the glass invalidate the question? >> >I can't go to the corner store and buy "lightning" -- does that >> >mean I can't inquire as to its properties? >> >> You answered the question with a question - not a good way to get >> information. > > I just love derogatory chatter :) >
If you consider factual statements to be derogatory... ;-)
Reply by Maynard A. Philbrook Jr. July 12, 20142014-07-12
In article <q863s9lns5bj03kpjvqlk39sio7f9esq7g@4ax.com>, krw@attt.bizz 
says...
> > On Sat, 12 Jul 2014 10:33:07 -0700, Don Y <this@is.not.me.com> wrote: > > >On 7/12/2014 10:02 AM, edward.ming.lee@gmail.com wrote: > >> > >>> I want to know what the *glass* sees! > >> > >> Which glass? It probably depends on the manufacturer. As you and > >> others pointed out, there are many ways of driving LCD/LED screens. > >> They have dedicated controller for the specific panel technology and > >> it is unlikely that you can use (or even get) the glass without their > >> controller. > > > >FORGET *GETTING* THE GLASS! > > > >Does the (un)availability of the glass invalidate the question? > >I can't go to the corner store and buy "lightning" -- does that > >mean I can't inquire as to its properties? > > You answered the question with a question - not a good way to get > information.
I just love derogatory chatter :) Jamie
Reply by July 12, 20142014-07-12
On Sat, 12 Jul 2014 10:33:07 -0700, Don Y <this@is.not.me.com> wrote:

>On 7/12/2014 10:02 AM, edward.ming.lee@gmail.com wrote: >> >>> I want to know what the *glass* sees! >> >> Which glass? It probably depends on the manufacturer. As you and >> others pointed out, there are many ways of driving LCD/LED screens. >> They have dedicated controller for the specific panel technology and >> it is unlikely that you can use (or even get) the glass without their >> controller. > >FORGET *GETTING* THE GLASS! > >Does the (un)availability of the glass invalidate the question? >I can't go to the corner store and buy "lightning" -- does that >mean I can't inquire as to its properties?
You answered the question with a question - not a good way to get information.
Reply by Tauno Voipio July 12, 20142014-07-12
On 12.7.14 19:32, Don Y wrote:
> On 7/11/2014 1:17 AM, Tauno Voipio wrote: >> On 11.7.14 03:56, Don Y wrote: >>> On 7/10/2014 1:02 PM, Tauno Voipio wrote: > >>>> You might be able to tie all rows together and all columns together, >>>> and drive the rows and columns with antiphase square waves. The >>>> hard part will be to find the proper voltage levels. >>> >>> I would suspect that would work on "dumb glass" (i.e., where the >>> rows and columns were just electrodes screened on the glass). >>> >>> But, I thought larger panels had some active components *in* (on) >>> the glass to effectively treat the display as a storage device >>> that is "refreshed" with new data, periodically (?) >> >> For monochrome panels, the usual chip was KS0083. It is a 80 bit >> shift register with LCD output level shifters. > > This seems similar to the Hughes (?) devices I used ~1980 (though > they were DIP40). IIRC, the output was "multivalued" -- not just > a simple (2 level) translator -- to ensure DC stayed off the glass. > >> For a 320 by 240 display, there were 4 KS0083's for columns and >> 3 chips for rows. The data was fed serially to the column chips, >> with the rows clocked once for each full row. I used a refresh >> rate of 14400 row/s, giving 60 frames/s. > > Yes, similar to the Hughes interface -- though I was driving a > much smaller display (7x95). OTOH, a fair bit of overhead for > a machine with a 2MB/s bus! > > But, how does this all relate to current technology? My understanding > is that new panels are treated almost as a sort of write-only DRAM. > The electrical interface serving to store a charge in each "accessed > row's" column cell instead of just presenting an instantaneous > voltage across each cell.
Actually the output was 6 levels, to cater for the multiplexing and DC avoidance. See the KS0083 datasheet, it is still available in the Net. -- -TV
Reply by Don Y July 12, 20142014-07-12
On 7/12/2014 10:02 AM, edward.ming.lee@gmail.com wrote:
> >> I want to know what the *glass* sees! > > Which glass? It probably depends on the manufacturer. As you and > others pointed out, there are many ways of driving LCD/LED screens. > They have dedicated controller for the specific panel technology and > it is unlikely that you can use (or even get) the glass without their > controller.
FORGET *GETTING* THE GLASS! Does the (un)availability of the glass invalidate the question? I can't go to the corner store and buy "lightning" -- does that mean I can't inquire as to its properties?
Reply by July 12, 20142014-07-12
=20
> I want to know what the *glass* sees!
Which glass? It probably depends on the manufacturer. As you and others p= ointed out, there are many ways of driving LCD/LED screens. They have dedi= cated controller for the specific panel technology and it is unlikely that = you can use (or even get) the glass without their controller.
Reply by Don Y July 12, 20142014-07-12
Hi Lasse,

On 7/12/2014 6:25 AM, Lasse Langwadt Christensen wrote:
> > but if he only wants all white/black he doesn't need to drive pixels all > he need is a clock ~25MHz, hsync/vsync and all the color bits tied high/low > to get white/black
No, that requires some electronics along with the "glass". I want to know what the *glass* sees!
> an AVR/PIC etc. could do that > > -Lasse