What I'd like to see on my next Musical Keyboard - Page 1
Forum section: electronics / general

author: happyrat1
author_rank: Contributor
timestamp: November 11, 2014, 09:47:39 am
content: As well as every keyboard ever to be made in the future by every manufacturer.A velocity sensitive, optronic musical keyswitch.If you're like me, you're sick and tired of those stupid little suction cup switches either wearing out or sucking every piece of bar crud around until they cease to function properly.It may cost a little more but why the hell aren't keyboard manufacturers using optical switches instead?Here's a simple design that adapts an off the shelf ready made optical interruption sensor to measure the velocity of a struck key by using software to determine the time from which the contact is first broken til when it is re-established on the downstroke.This is childishly simple switching technology on which patents expired decades ago and it is bulletproof, smearproof and if it ever fouls up with dust bunnies, a simple vacuum cleaner can render it good as new again.Here ya go boys. With my compliments.I'm passing this on to every keyboard manufacturer out there tonight and you can all murder each other for the patents, if there are any to be had.Like I said, it's a simple application of an existing technology that's over three decades old.At the very least, start using this in your higher end machines.Garyhttp://wiring.org.co/learning/basics/opticalsensor.html

author: Andy Watson
author_rank: Super Contributor
timestamp: November 11, 2014, 10:12:48 am
content: What happens when the key is pressed sufficiently to break the contact, but not far enough to remake the contact?

author: Muttley Snickers
author_rank: Unknown
timestamp: November 11, 2014, 10:34:49 am
content: Gary,You might be wise to edit the picture and remove your surname, Public forums in general can attract some twisted people.Also, I have a Roland EXR-5 that has velocity sense and it works fine and is fully adjustable via program setting's.Not sure what keyboards you are refering to with suction cups.Muttley

author: happyrat1
author_rank: Contributor
timestamp: November 11, 2014, 10:42:33 am
content: Andy >>> I'd imagine the same as the membrane switch models. The pulse would stretch to a maximum value and thus record as minimum velocity or no keystrike at all.A piano doesn't play until the hammer actually strikes the strings as well. Partially depressing the key has no effect until the hammer is actually released.This technique could just as easily be adapted to hammer action keyboards as well.Muttley >>> while I cherish my internet anonymity as much as the next man, valid contact info is a necessity should there ever come a need to establish prior art and first disclosure in a court of law.Muttley >>> Virtually all electronic keyboards today use a pair of silicone membrane switches roughly shaped like suction cups to record top and bottom position of the keyswitch. It doesn't matter if we're talking $50 Casio or $5000 Kronos. They've all been using the same membrane switches for the past 30 years.Gary

author: Andy Watson
author_rank: Super Contributor
timestamp: November 11, 2014, 11:04:05 am
content: May be I have missed something on your diagram (?), I'll put the question slightly differently: You appear to have only one contact, how does the controlling software know the difference between a key that travels all the way, generating an on-off-on sequence, and a key that travels half-way and back to the top, which also generates the same sequence?

author: Muttley Snickers
author_rank: Unknown
timestamp: November 11, 2014, 11:06:56 am
content: What would happen then if a musician was on stage playing to a large paying crowd and a group of cockroaches decided to dance around inside his or her keyboard, triggering the key's or the smoke machine went nut's.That I would pay to see and hear.Muttley

author: happyrat1
author_rank: Contributor
timestamp: November 11, 2014, 11:11:52 am
content: Good point Andy. But the software could be intelligently designed to discard out of range pulses for excessively slow pulses and as for partially hitting the occasional accidental note, it happens already from time to time on the cheaper keyboards out there already. Sometimes I have seen cheap keyboards "stick" on a note until the key has been fully depressed again and the key has "reset" itself.Then again a more expensive design could use a single LED and a pair of photodiodes or phototransistors to generate glitch free logic states without the occasional stuck note. That would be up to the manufacturer to decide whether or not the price of the board justified the additional manufacturing cost.Gary

author: coppice
author_rank: Super Contributor
timestamp: November 11, 2014, 11:31:48 am
content: Quote from: Muttley Snickers on November 11, 2014, 11:06:56 amI think they would probably be partially hitting a lot of keys adjacent to the ones they are really trying to hit. That's what I see most people do. Your scheme can't tell the difference between a downstroke and an upstroke, so I guess you aim to assume that every alternate break->make->break sequence is to be ignore. If you can fool the scanning just once, every subsequent note will play on the upstroke instead of the downstroke. Using optical seems a bit iffy, if dirt is your main problem with the existing solution. Even if your light is bright enough to shine through any fluff that builds up, dirt is going to affect the sensitivity at the receiver and the instant at while make or break is declared. That means dirt will change the touch sensitivity, probably in an inconsistent way along the keyboard, as most dirt will build up where your hands spend most of their time.

author: happyrat1
author_rank: Contributor
timestamp: November 11, 2014, 11:44:50 am
content: Actually, the single sensor approach would work just fine even on the most demanding keyboard designs.First of all keep in mind that my crude illustration is not to scale.With some properly squidgy ergonomic engineering, the actual sensor can be placed waaaaay down toward the bottom of the stroke. Since velocity remains pretty much constant throughout the key's travel, you'd only have to measure it at the bottom couple of millimetres of the stroke to determine the pulse width and therefrom calculate the velocity of the note. Clock cycles being in the nanoseconds range means that velocity could be accurately calculated at the final 3 or 4 millimetres of the stroke and any accidental, partial presses wouldn't even register to begin with.I'd assume this type of human interface engineering is what already differentiates my $150 piece of crap M-Audio from my $3000 KurzweilGAry

author: happyrat1
author_rank: Contributor
timestamp: November 11, 2014, 11:55:57 am
content: As for dirt obscuring the optics of the sensor, a simple self cleaning wiper design could be implemented as well. Though I'd seriously doubt it would be necessary. It would take many, many years for the dust bunnies to build up to the point where it would become necessary to open it up and vacuum it out.And another advantage to this design is consistency and precision. Using optronics simply HAS to be more precise than using moulded rubber mechanical switches.Gary

author: 22swg
author_rank: Frequent Contributor
timestamp: November 11, 2014, 02:15:16 pm
content: Your interrupter needs two slots in it so keys go from on-off-on , or even several slots for various attack / velocity control...

author: happyrat1
author_rank: Contributor
timestamp: November 11, 2014, 05:50:08 pm
content: No. One simple bar is all you need. Using negative logic, you go from On to Off to On and handle the conversion in software.All that's required to determine key velocity is the width of the off pulse.Actually though, on further thought, it may even be possible to add aftertouch at the bottom of the stroke by depressing the key into a rubber cushion and adding a second bar that engages at the bottom of the stroke. Not sure how it would handle misfires though. It might not be workable.Gary

author: happyrat1
author_rank: Contributor
timestamp: November 12, 2014, 12:51:34 am
content: Just for sh*ts and giggles I modified the design slightly to work with two off the shelf sensors for anyone out there who wants to take a whack at building one of these homebrew style.Truth be told there are probably a hundred possible working geometries and permutations that could be based on this simple device but I have neither unlimited financial resources nor unlimited legal talent at my disposal to try and engineer a bulletproof patent on my own.For that reason I've opened this up to the forum where everyone is free to experiment with mine and their own designs.Just keep in mind this can work with light pipes, reflectors, multiple or single sensors, and an almost infinite number of optimized layouts and geometries.If anyone out there is planning to file patents on this, be warned, that this is still basically just an optronic switch, and there's dozens of ways to skin a catGary

author: happyrat1
author_rank: Contributor
timestamp: November 13, 2014, 04:18:27 am
content: We've also been discussing this over on the Kurzweil Forums at Cunka.comOne member over there came up with a simply brilliant single sensor solution to the accidental misfire problem.Kudos to the man for taking this to the next level.http://www.cunka.com/forum/index.php?topic=4252.0Gary

author: grenert
author_rank: Frequent Contributor
timestamp: November 22, 2014, 05:58:41 pm
content: Hi, Gary.The old Sequential Circuits Prophet T8 used optical velocity sensing:http://www.soundonsound.com/sos/1996_articles/oct96/prophett8.htmlYou may find the service manual interesting:http://www.univertron.com/SAS/manuals/Sequential/Prophet-T8/SCI%20Prophet%20T-8%20service%20manual%20_cleaner.rarUnfortunately, no good information on the mechanical aspects of the keyboard.

author: sync
author_rank: Frequent Contributor
timestamp: November 22, 2014, 06:58:20 pm
content: I have seen some very dirty keyboards. I don't think optical sensors are a robust enough. I would use hall sensors for non-mechanical switching. They are very reliable.

author: sync
author_rank: Frequent Contributor
timestamp: November 22, 2014, 07:02:14 pm
content: Quote from: happyrat1 on November 11, 2014, 11:55:57 amThis doesn't help against liquids (soft drinks, beer), right?

author: happyrat1
author_rank: Contributor
timestamp: November 22, 2014, 07:57:44 pm
content: Grenert >>> Thanks for the schematics and the article link. The RAR file is poorly indexed so it will take me some time to scan thru it later on, but from what I could make of the article, Prophet's big failure was a question of being ahead of their time as well as the limitations of CPU speeds back in 1981.I seriously think if the big manufacturers of today were to revisit the optronic switching model they'd be able to produce a straightforward, modular, reliable switching unit for under a dollar a key.Even the article went on and on about the benefits of optronic switching and how much better it was than anything else on the market, but a 1981 small entity operation definitely lacked the resources available today to keyboard giants like Fatar and Yamaha and Casio.I'll go thru the schematics later tonight when I have time.Thanks again,Gary

author: happyrat1
author_rank: Contributor
timestamp: November 22, 2014, 08:03:03 pm
content: Sync >>> I'd considered Hall effect but discarded the idea based on cost per unit.Also as far as liquids go, making a keyboard beer proof simply is not part of the design spec. Would you toss out your PVR simply because the manufacture didn't rate it for beer spills? Of course not.Just as one would not normally dump a bucket of sand on a piano one would also hopefully not be stupid enough to rest their drink on top of a thousand or two or three thousand dollar instrumentGary

author: vikasbly44
author_rank: Contributor
timestamp: February 23, 2015, 11:09:59 am
content: Dear.....good thing, you need two slots in it....then it is more interactive.and effective...

author: Zucca
author_rank: Unknown
timestamp: March 28, 2015, 07:14:04 pm
content: Hall Sensors, Please

author: Michaela Joy
author_rank: Contributor
timestamp: March 28, 2015, 08:43:25 pm
content: I own a pair of Roland A-33's for almost 15 years now. Only recently did one of the keys go "dead". For about $10.00 USD, I was able to get a replacement rubber strip and fix the dead key.I have to say, that's pretty impressive for a rubber strip key bed.As a keyboard player, I have some questions: What kind of weight increase are you going to incur by using an optical / hall effect keyboard? Will moving above said keyboard around throw it out of adjustment? How easy is it to service, should a problem arise?If you're going to keep it in a recording studio or at home, or do it just for the fun of it, then your optical keyboard is a novel project.However, I just don't see it surviving the rigors of playing out.:MJReplacement parts for keyboards:https://syntaur.com