 let's begin with the scanner system okay so how scanner works okay so as as you can see you'll have a computer then you have a connected scanner to it and then the scanner will have like no a lot of these elements of mechatronics system that we have seen so there'll be actuator there'll be a scanner head and then like as a as a as a plant then you you get something from the scanner head which is like you know that lines can like no image with the image sensor you get like actually the image of the page and that case goes to microcontroller but again here is this image of feedback probably not okay so we'll see what is what is is there any feedback or required in the space or not okay all those kind of things now we will start looking at so it's also very interesting system for you know scanning with the with the color scan of course nowadays you have your mobile phone you can just directly use like you know this scanner scanning application and like your scanning of the documents can be done with the it's simple mobile images and things like that but for xerox sync purposes and for scanning purposes okay so this now a lot of these sophisticated systems have come with much more automation than what you have in the scanner that we are going to see okay so what we are going to see is a simple scanner where you you have like let me see this picture here okay so let's see the picture first and then yeah so this is a kind of a scanner we are going to see okay so it it doesn't have any paper feeding system or auto kind of you know scan of any entire document kind of a stuff okay which is there in the not a lot of modern xeroxing and photocopying to be precise and scanning systems okay so again our goals here are similar as we had for the CDROM system given a problem how to synthesize a mechatronic solution you need to have a thinking done now that we are equipped with a little more the kind of a knowledge based on the CDROM drive one can think for the scanner kind of very easily probably okay then again thinking in in both like you know multiple domains together and see whether there are any kind of a solution that we can give mechatronically in this in this kind of a system and again observe other solutions that people have given in the like you know this professional solutions that people have given for such a system and learn from it okay this is kind of standard process that again we'll go through so what is the problem at hand now so this problem is simple so function of scanner you all know that okay you have a page and page has some kind of color and maybe black images black parts in the image and that image we want to kind of have you know scanned and converted into a digital format which will be displayed on your computer or you can be used for many other purposes okay so and typically the data in this is red line by line we are not taking a picture immediately and like you know using that picture as a as a scan data okay so this this will have a much more higher resolution of image that can be possible with the scanner okay that is what we we we will do here okay and to get that now can you think about pause here and think about okay what solution comes to your mind okay based on whatever scanner use that you had already done what is the kind of systems that that this scanner needs to have it's not very difficult to think like one one can know that okay I need to scan a page with the with the some kind of a sensor okay so the the head should move across the paper in some way right that is clear that so that some kind of a motion system should be there which can move the head of a scanner on the surface of a paper okay and as it kind of moves the head of the scanner on surface of paper it should scan line by line okay the data should be getting like no line by line the data should come into the now what is this data how do you kind of get this data what kind of sensors you should have to get this data can you think about okay so then it then they need to be something like a light sensors okay so how this like light sensors will be doing the job of sensing and like not doing this kind of a scan so this is what you you need to think about and like no see okay what is the way uh this light sensors can be employed to kind of like no register the data across one line in one go probably because like no you move this head on the surface of a of a paper uh and read one line next line next line like no keep on reading like that as the paper is moving okay so the speed of motion of the of the head will be governed by how quickly you are able to kind of like no register the data for single line scan okay so let's start looking at it again so these are the questions that we raised how the page is is scanned okay and what are the sensors actuators there um what is a sensor that converts the paper into digital kind of a form output and preserves still preserves the color and the sensor width now needs to be same as paper width or snow okay think about this okay so one can easily see like you know some kind of a solution can emerge for the head to move that we can use some stepper motor as as we have seen the CD ROM drive um now do we need what is the accuracy that is needed again here if you want to think about what is the accuracy uh that is needed for the um uh motion here okay so that is not as fine as you have seen in the CD ROM drives okay so probably for this application you don't need to employ any compliant mechanisms okay is that okay is that make common sense like okay yeah the accuracy may not be so high right so um so so we'll see like you know how how this accuracy can be able to see is whatever this kind of accuracy that is needed that is achieved but it did not be definitely very high in nanometric position it may be some 50 micron 100 micron kind of accuracy it can be okay with in one particular kind of a direction if you keep on scanning then like you know that there is no direction reversal that is happening here there is another thing to note okay that I start scanning I don't have to reverse the direction anytime you can see that unless unlike in CD ROM drives like you know my head can go forward and backward as it scans like you know the entire surface of this CD so I need to be able to kind of like know move both backward and forward there but in the scanning I just move only in one direction okay during the scan once the scan is complete of course you come back to the the normal position and like like you know continue whatever um you know next scan so so let's kind of like know start with the like you're seeing the scanner first okay and open up and see okay see when you open up the scanner and see just cover opening and to the class you can actually notice like you know that you have this black kind of a head here on that this white line okay what is this white line for okay what is there inside this box that is doing the job then you see that there is a flat kind of a connector which is running from here to here and like you know as the head moves this flat connector kind of folds and like you know doesn't give too much of a disturbance to the to the system or motion of this blackhead okay and then there is a small little kind of a circuit up here which kind of gathers data and communicates it to the computer okay so let us open further okay and see what is that we get now okay so what we need to observe is what are the different components that you can find and identify like know what are they for okay out of that these are the two system that we talked about one is like no motion system another is like no sensing the the the sensor system okay so and then like you know see the guide guiding in this case how this guiding in this case now can you connect relate this whatever guiding is happening in this case to what we saw in the CD-ROM drive okay so let us start like no looking at these questions here so as you open up the the top cover here okay there are some screws which have to be removed from the top cover here and here and you'll be and then some kind of a mechanical interlock will be there and you'll be able to open this then you can observe there is some kind of a drive system here okay typically this has a stepper motor why stepper motor because you if you see on this motor also you'll observe there are four terminals that are coming out okay then there is some kind of a gear system we'll open up that and check what is that gear system and then there is some kind of a drive here so this belt runs over the entire kind of like you know the wheel up here and then there is some kind of idling wheel up here okay and then this head is guided by this guide rod okay this is steel rod which is which will guide this head here and then oops we where is other guide there's only one guide here okay let's think about where is the other guy what is acting as other guy can you notice something in the other side which will which will make sure that it is guided at at two guides and no it cannot have just one one single kind of a guide okay so what is that guide on the other side is what you need to think about okay let's proceed further so this is motion as you see is in this direction and then this is like a like a very bright mercury kind of a lamp here okay mercury tube here very thin but like you know very bright mercury lamp okay and then like you know for this lamp to be driven there you need a you need a good amount of current so that these wires if you see these white wires that are going to circuit and they are quite thick they are not very very thin wires there okay the thick wires are needed for the higher currents that are to be carried with the tube okay now what is inside this black box it looks like a black box it's really a black box to see and then like no we see what is there in this box to kind of can you imagine what is there what could be there inside so let's see so this first we observe these guides okay so these are the guide this is a one guide for the motion motion system this rod that we have seen okay so here like no you it goes inside but inside like no we will show later that it is actually guided by at two points okay so two points it is going through as we have seen in the in the CD ROM drive system on one side it goes to these two side supports why that is needed because okay think about that okay you think about that why you need two points okay even if it is guided here like no it will be yeah this is other point it will be guided okay so observe carefully that okay there is some kind of a small protrusion coming out on the surface of this bottom okay that protrusion is actually guiding like you know it's kind of a resting this system is resting on this protrusion by gravity okay you don't have if you lift it it will kind of get lifted up but I mean you know there is nobody to lift it when it is all packed and covered system okay so then it will not have much of a problem so there is no like a rod kind of a guide but it's just a small protrusion that is coming out they have saved the cost of the rod and assembly okay by by means of this kind of protrusion which is sufficient to to make sure that today it is guided on the other side also now this is full fully guided means like you know it is having a rod fully covered on all the sides by a by a guiding sleeve okay and this is is not on somewhere here okay it is it is on this side okay so why this guide on this is this side not on the opposite side okay you may say okay oh there is a circuit on this side okay you know I can I could have circuit on on the other side on somewhere in the middle I mean there's a space up here whatever I can have circuit on whatever wherever wherever I want okay but there is a specific reason for this rod to be on on this side particularly close to this motor okay close to its drive okay think about that think about a free free body diagram when they when the motor starts operating and like no starts moving this head what are the forces and moments that are coming on the system and then like no you may understand this part okay if you see this motion system a little bit more in details like no you if you see this a motor here you remove these three screws and like no you'll see that there is a upside down you can see there is a motor which is driving a gear opinion which is like no with the gear reduction driving this this wheel which is on which like you know this belt is going okay so this is a two third wheel on which this two third belt is is is mounted and that belt is running all across the drive and there is something like a spring here okay what is this for okay so think about this is like no if you see that this is just kind of a spring and then like no the the belt goes inside that and like no it is when you strengthen the belt it will have some kind of a tension okay so so these are questions that we need to kind of address here now is there backlash compensation in this system okay you we don't see it here you cannot see that okay there are two gears which are like no spring loaded or something like that so is it really required there okay so it's probably not can you think and justify why it is not okay because you don't have a very high precision positioning system here first thing and second thing like no once you start driving in one direction you are not going to reverse the direction at all right so you keep on driving in one direction so then there is no backlash question comes in comes in there even if there is a backlash in the system it's not going to harm your application okay so you you you see that it's it's very interesting way like no that okay this backlash doesn't bother for for this application okay so you don't have to kind of compensate for backlash for everything like no only where like no you have to make sure that okay the application is is requiring this need for compensation backlash then only you need to do that okay so okay another thing why there is a two-thread belt here okay one could have used like you could have used here a normal belt also okay why two-thread belt okay so this belt will make sure that it will not slip this belt will not slip from the motor and there'll be like no when the motor is driving like you know it's a positive drive that will happen to the to the system with the stepper motor okay okay so so in case okay in case of trouble where like no there is the head gets struck in this particular case then what will happen is like no stepper motor will start losing some steps okay and then might be some way electronically to detect that okay the stepper motor is losing some steps okay you another thing you might notice here that okay in the entire system if you have opened up and seen like you know there's a motor here but on the motor there is no sensor okay typically like you know you'll you'll find otherwise like no the additional kind of a sensor sitting on the top of the motor and neither there is a sensor in this belt or any other place for the motion sensing so why there is no need for the sensor position sensor here okay if you ponder over like no little bit you'll find it okay oh yeah this there is no need for the motion sensor because as you start like no saying like no operating motor in one direction okay it starts scanning and then as it continues like no it's uh motion with the same we know number of steps that are given will be proportional to the position of the of the head okay in one particular direction if i keep on driving the same direction exactly that number of steps are that are given will be now when i reverse the direction then my count may not match okay because of the backlash in the system okay so that's where like no uh this is a elegant kind of a way they have eliminated the like no the sensor in the system i keep driving in one direction and like no i get to know okay now uh where to start let me know this is starting there is a for starting to know where to start like no there is a small uh limit switch uh inside the thing okay so that limit switch i don't think i have a photograph of it but there is a limit switch inside the head somewhere okay which keeps on doing the sensing of the data now so this little thing here that you see with the spring loaded is it's for the um tensioning of the belt okay so you can see the tensioning of the belt here okay when this tension is released like no this this spring kind of gets uh no tension inside it but if you see this stretch belt is stretched like no spring will be under tension here okay so this is the thing that you can observe here okay yourself it's interesting kind of a mechanism to kind of make sure the belt is tight so that like a small amount of backlash uh at least will be um taken care of in in the dry in the bed it's not a like no backlash sorry it's a slack in the bed okay so otherwise beds being so long it will have a tendency to slack okay and then also like no if you see this is very interesting way the manufacturing errors in the um in the assembly would be taken care of say for example if uh the the motor is mounted a little bit uh here and there okay in in position you know the bed will not get slack okay the bed tension will be maintained by by using the spring and this will be very nicely it will kind of operate and bed is kind of firmly head to the to the head in this in this particular place here and next to it is a spring so the spring will not come uh into the it will not go ever over the pulley okay the spring part of the portion of the bed will not ever go over the pulley okay so then like no so you have this one continuous bed and it is spring loaded here so it's spring tightened here and even if you have some errors in the assembly of of your motor they are not going to be your your belt is not going to go slack that too that's what is is made sure because of this kind of an interesting way of doing things okay so the accuracy or the skill that is required in the assembly is is is uh avoided here okay now uh this is another kind of a uh you see the similar subsystem for scanning this is in the printer okay if you see printer on the top there are some printers with the scanner like no combined system is there so in that system we will have this kind of a arrangement this is another kind of a scanner opened i would say okay uh so we have seen these are the subsystems so far like no scanning heads of system and sensor for recording the scan and then you'll have data communication plus head and control systems and things like that okay so uh now let's move on to this second system which is a sensor system okay so if you see this black box opened okay you'll observe all these kind of elements can can this make sense okay so you see that there is a there is a this big size something glass kind of a thing here and then there is some some other kind of a glass kind of a thing here some other kind of a thing here then similar kind of a thing here and and how do you kind of make sense of all these things so if you see carefully these are like no these are not just glass but they are kind of mirrors here okay if you carefully observe them they'll be you'll see that okay they are actually mirrors okay and uh this is the first mirror which is like no length of the paper size mirror okay then there are subsequent mirrors where which sizes are like no smaller and smaller this is smaller mirror then this is smaller mirror like that there are smaller and smaller size mirrors that are happening okay so um if you see the angles at which they are placed then like no you see that okay the one mirror reflects on the surface of other and like no and so on and so forth like okay so um so image is is is full length of the paper image which is coming on the top surface of the it is a imaging there is a glass we have removed that glass so from the glass the the the whatever is written on the paper will come as a as a reflection on this surface here and this mirror is at at some angle such that like you know this reflection comes on this surface here first from the top illuminated by uv or like that mercury lamp and then it will get reflected on this surface so so this angle is such that the the mirror this reflection of this image of the paper like no goes here then from here it goes to the next mirror here okay this so you see this is uh smaller mirror than than this mirror okay then like no you'll have a further smaller size here okay and then from here further smaller size uh it will it will go on this mirror and from here this is like no about an 45 degree angle so it goes down from here okay like that okay now we'll see what is what happens when it goes down okay so there is some other kind of a system that is expected down there so this is what is there in this kind of a black kind of a box that you are black head that you are seeing uh for for this system okay so this is a reflector system for the optics okay and you can notice that you know every time it getting reflected there is a reduction in the size happening that means uh are we losing the image here no no no we are not losing the image what these mirrors are they are not like a normal mirror they are like a concave kind of a mirrors okay so they'll kind of like the sense the the larger size and like no focus it in a in a on the next mirror in a smaller kind of a size okay because they're concave kind of a mirrors okay so that is what is uh important here to see okay that is what it means that every mirror is a concave mirror every time the reflection happens the the size of the you know what is whatever is reflected keeps on reducing okay why why would the size reduce or why it is needed to be designed that way we'll see okay so what happens to the system next okay you go to come down okay this now upside down here okay when you see upside down like no this is a mirror which is which is receiving the input from what the arrow that pointed down there so it is coming up here okay because it's like no image taken from the bottom side and now there is a final kind of a concave focusing happening into this system this is a lens here okay this lens would look something like that okay if you see this is the the image of deflection from this final mirror we'll get on to the lens and it will create an image on the sensor so this is a virtual image that will get created on the surface of a sensor the sensor is is up located up here okay so this is a sensor in which like on which this mirror the image gets gets virtual image will get formed on the surface of the sensor okay so far so good what you see here is is this little circuit which actually drives the mercury tube that that we have seen that white light kind of a tube there okay now we further open up this okay you open up this lens and open up this sensor things will look like this okay so this is a lens up here okay this was a PCB that I was talking about for the light things and this this wires are kind of thick wires which are for high current current carrying capacity to so this wire one goes on this side and that goes on this side to to connect to the mercury lamp now what is there inside this chip can you imagine now okay what could be there inside this chip okay so think about it if you observe under microscope okay this is the first kind of an image or this is like not a microscope but this is like a zoomed image of the of this sensor okay you see some kind of a you know big line here and then there are some wires that are connected and there are some these golden parts pads are like basically the points where the the the wires are connected from the these points the the chip carrier okay this package has these pins okay so these pins will be connected finally to these small small small little pads that you see there under microscope we need to observe the sensor to kind of really make sense what is happening there okay let's kind of do that so if you see this image under microscope you'll see that you know these are the golden pads which are which are seen up here on one side only okay these other golden side pads are not in this zoomed microscopic image and you'll see these are the wires that are coming to golden pads from from these different parts of this main sensor strip this is like a main sensor strip okay on which like you see there are some sensors elements start up here okay these are part where the connections or contacts are made for electrical elements and then there is a sensor pad that is up here and other end of the sensor pad we can see here and it's under microscope like in like there is one one wire that might be multiple wires connected on the other side but there are some circuits up here which are doing some local processing of the signal before it is taken out of the sensor from these wires to to the to the pc now if you zoom in this area further you'll find like you know there are these red green and blue parts here can you imagine what are they why there are red green and blue parts and below that there will be probably the the sensors sensor elements you see these small small small like you know the lines here or dots there they are like a sensor element and the sensor element is covered by by this red kind of a patch okay and then there is a green patch and there is a blue patch okay so these three sensing tracks okay will get from the image these three rg and b parts of the image okay so the the big illuminated image is falling on this surface here of these three tracks and like you know these these are the three filters which are filtering like you know the image to kind of get rg and b parts of the image saved so that we can reproduce the color for the image in in the in the nice way okay so this is a this is an arrangement for getting like you know the colored image very nicely done okay so so this is what is making like you know the colored image sensing possible okay so then finally we'll have this PCB for control and like no communication now control in this case is not really a closed loop control it's like open loop control it's just keep on sending these the steps of you know drive to the stepper motor and stepper motor keeps on like no going until until the the end is hit okay until the paper end is hit so you have seen you might have seen like no in the pay in the in this kind of a scanners even if your page is half okay the scan is still made full okay you cannot control that okay i want to scan only some part of the page okay what is the reason because they don't have a sense sensor to kind of sense where the page is ending can you see that okay so that's the reason like no you don't kind of have a have a scanners to typically have scanning for this kind of a simple scanner there might be some sophisticated it's sophisticated scanners which might have like no little more kind of flexibility to kind of control where you want to exactly have exactly the scan but typically you'll find that okay even if you are scanning you say your passport okay you need to keep typically run this full scan and then like no once the scan image is there in the in the in the computer then you kind of crop that image and like no remove the part that you don't want but as a scanner like no has no smartness to kind of register that okay only this part of the image is to be scanned and like no given to you okay so that is how like no the scanner works okay so again here you can list down you know your summary lessons here