Post by thread:[OT]: Dollar bill acceptor

Hello Howard, I have always wondered how these bill-acceptor machines are able to distinguish between the bills of different values. Do you also make the dollar-bill acceptor? Would you happen to know which sensor(s) is used and how the machine distinguishes between the bills so accurately? I would assume that there is some form of scanner which does an image-comparison, but am wondering how it is able to take care of the image-noise (dirty, folded bills) and at such high speeds (DSP?)? PICers, Normally I would have sent this mail only to Howard, but possibly the answers would be interesting to others on the list too. I apologise to the rest. thank you with best regards Sujay Sirur -----Ursprüngliche Nachricht----- Von: Howard McGinnis [spam_OUThmcginniTakeThisOuTDIGITAL.NET] Gesendet: Dienstag, 8. August 2000 17:37 Betreff: [PIC]:[OT]: Thin Film Heaters I hope I got these prefixes right on the subject line. Our 16F873 based controller (there's the PIC tie in) is attached to a dollar bill acceptor. The dollar bill acceptor has a tendency to freeze up (exposed somewhat to the elements) during the cold northern winter. Our customer in the past has used a 40 watt light bulb to keep the interior toasty to prevent icing and I am trying to locate a source of thin film heaters that operate in the 24 VDC range. Any sources? Thanks, Howard Howard McGinnis .....hmcginniKILLspam@spam@digital.net Electronic Visions, Inc. 1650 Barrett Drive Rockledge FL 32955 (321) 632-7530 http://ddi.digital.net/~hmcginni mcginnisKILLspame-visions.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

> I have always wondered how these bill-acceptor machines are able to > distinguish between the bills of different values. Do you also make the Distinguishing between bills of different values is probably done in an analagous fashion to how you or I differentiate bills. The "real" question is the machine distinguishes bills from high quality counterfeit bills. So, here's what I know: The ink used to print US currency contains some sort of ferrite particles in it. The sensors in the bill changer don't look at the visible spectrum, but instead at some magnetic spectral response. > assume that there is some form of scanner which does an image-comparison, > but am wondering how it is able to take care of the image-noise (dirty, > folded bills) and at such high speeds (DSP?)? Noise would be a problem, but I imagine a little bit of pre-processing of the image can help thigs out quite a bit. (contrast stretch + gaussian smooth..) Then do a convolution with certain features that you know you are looking for (ie the 1 in the upper right corner, or whatever) and then accept the bill if the response is high enough overall. Else try the image features of the $5 bill, and eventually reject the bill alltogether. As far as the high speed part, I imagine all of the image processing stuff is implemented in hardware, making it fast enough. -Steve -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

I don't know how the bill acceptors work. I do know that the Mars models have a ROM that contains the information to recognize the bills. Each time the US Treasury comes out with one of the new bills, the ROM must be changed to know about them. It would be interesting to know how big the ROM is to hold the data needed to do this. For instance, will they hold enough data to recognize all of the old bills as well as all of the new bills? -- Rich "Sujay Sirur (K3/EFS3)" wrote: {Quote hidden}> > Hello Howard, > > I have always wondered how these bill-acceptor machines are able to > distinguish between the bills of different values. Do you also make the > dollar-bill acceptor? Would you happen to know which sensor(s) is used and > how the machine distinguishes between the bills so accurately? I would > assume that there is some form of scanner which does an image-comparison, > but am wondering how it is able to take care of the image-noise (dirty, > folded bills) and at such high speeds (DSP?)? > > PICers, > Normally I would have sent this mail only to Howard, but possibly the > answers would be interesting to others on the list too. I apologise to the > rest. > > thank you > with best regards > > Sujay Sirur > > -----Ursprüngliche Nachricht----- > Von: Howard McGinnis [.....hmcginniKILLspam.....DIGITAL.NET] > Gesendet: Dienstag, 8. August 2000 17:37 > Betreff: [PIC]:[OT]: Thin Film Heaters > > I hope I got these prefixes right on the subject line. > > Our 16F873 based controller (there's the PIC tie in) is attached to a > dollar bill acceptor. The dollar bill acceptor has a tendency to freeze up > (exposed somewhat to the elements) during the cold northern winter. Our > customer in the past has used a 40 watt light bulb to keep the interior > toasty to prevent icing and I am trying to locate a source of thin film > heaters that operate in the 24 VDC range. > > Any sources? > > Thanks, > Howard > Howard McGinnis > EraseMEhmcginnispam_OUTTakeThisOuTdigital.net > Electronic Visions, Inc. > 1650 Barrett Drive > Rockledge FL 32955 > (321) 632-7530 > http://ddi.digital.net/~hmcginni > mcginnisspam_OUTe-visions.com > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

Richard Ottosen wrote: >I don't know how the bill acceptors work. I do know that the Mars models >have a ROM that contains the information to recognize the bills. Each >time the US Treasury comes out with one of the new bills, the ROM must >be changed to know about them. It would be interesting to know how big >the ROM is to hold the data needed to do this. For instance, will they >hold enough data to recognize all of the old bills as well as all of the >new bills? > This is probably pretty closely held information, as it gets into the whole realm of counterfeiting. If the scheme is too simplistic, then a xerox copy would pass. Wouldn't want that, would we? [but maybe one of the echelon moles activated on words like "US Treasury" and "recognize ... bills" might perchance come forth and tell us - guys??????]. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

Surjay, We do not make the dollar bill acceptor, only the controller that interfaces to it. What I have gathered from the documentation is that the validator has 3 optical sensors, right, center, and left and a magnetic sensor of some sort to allow it to accept coupons. Howard Howard McGinnis @spam@hmcginniKILLspamdigital.net Electronic Visions, Inc. 1650 Barrett Drive Rockledge FL 32955 (321) 632-7530 http://ddi.digital.net/~hmcginni KILLspammcginnisKILLspame-visions.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

Dan Michaels wrote: > Richard Ottosen wrote: [bill acceptors recognition scheme] > > This is probably pretty closely held information, as it gets > into the whole realm of counterfeiting. If the scheme is too > simplistic, then a xerox copy would pass. Wouldn't want that, Old change machines *did* accept Xerox copies. There were quite a few of 'em here in town back about 15 years ago or so. The arcade that used to be downtown was one of the places that had 'em. And no, I'm *not* going to admit to how I know that it worked. ::grin:: > would we? [but maybe one of the echelon moles activated on words > like "US Treasury" and "recognize ... bills" might perchance come > forth and tell us - guys??????]. Either that or that new thing ... Carnivore I think it's called? -- Mike Werner KA8YSD | He that is slow to believe anything and | everything is of great understanding, '91 GS500E | for belief in one false principle is the Morgantown WV | beginning of all unwisdom. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

I have some experience servicing bill validator equipment..... Two major brands of BV equipment are MARS and JCM. I have worked on the JCM brands. There are an array of IR emitter/detector pairs. There is a microcontroller and it is programmed with the information regarding each bill it is designed to accept. In my case, Canadian bills (even worse with the colors). The program basically samples bills at various points along the length as it is drawn in. If you notice, after the bill is drawn in, it is held (called escrow) while it compares the sampled data against a table. The sampling is analog and measures the IR light absorption of the colors and thickness, etc of the bill. The sensor pairs are typically arranged in groups of two. One pair with receiver on the top and the other with the receiver on the bottom. Generally there are two pairs in the middle, two pairs on the right side, two pairs on the left side. There are a couple of single pairs that sense the bill entering the head and one pair for exit. They have "anti-fish" rakes to stop people from pulling them back out. There are timing mechanisims and photo-interrupters in case it jams. After acceptance the "transport" and "stacker" units take and store the bill. If the bill jams during storage procedures, the bill validator unit will shut down and refuse further bills. Some units also have a magnetic sensor for embedded strips (US bills). The unit is fairly simple in it's interface. There is power (of course), and enable input, an accept/reject input and a pulse count output. When power and enable on on, the head will accept bills. If a valid bill is accepted, a series of pulsed (1 for each $1) is sent out. If the control equipment wants the acceptor to accept the bill (via the accept/reject signals) the bill is stored. Otherwise it is rejected (another reason for holding the bill in escrow). In the case of change machines, the control equipment is typically uC controller and will decide how much change to return if a valid bill is accepted. These companies are constantly updating their software to keep up with the talents of counterfeiters. YES, they have been known to accept very good counterfeits, but they have to VERY VERY good. The RCMP get involved (in Canada anyway) when they are this good. I have encountered situations where good bills get rejected. Our $5 bill was printed with a slightly different shade of blue in a serial number series beginning with BJ and it drove us nuts until we noticed it was only this series. These units are typically calibrated using special colored papers. I hope this helps you understand these gizmos. Are you planning to make one?? Whole units can be had for about $1200CDN, ready for mounting. But you would need some schematics to help in interfacing. John Mullan {Original Message removed}

At 09:21 PM 8/11/00 -0400, you wrote: >There are an array of IR emitter/detector pairs. There is a microcontroller >and it is programmed with the information regarding each bill it is designed >to accept. In my case, Canadian bills (even worse with the colors). > John's description appears to be very accurate with one little exception in the magnetic reader. This, at least in the CoinCo unit we are interfacing to, is used to read coupons. These are printed by the manufacturers using magnetic ink. We did some testing and found that our unit will not accept the new US dollars. We did this test when we couldn't find a common strip for any optic path (left, right or center) common to the old and new $5 bills. For the coupons, CoinCo says that the units must be programmed to recognize the "signature" of the coupon and I think that this is also true with the bills. Howard Howard McGinnis RemoveMEhmcginniTakeThisOuTdigital.net Electronic Visions, Inc. 1650 Barrett Drive Rockledge FL 32955 (321) 632-7530 http://ddi.digital.net/~hmcginni spamBeGonemcginnisspamBeGonee-visions.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.