Dr. M.G.R. EDUCATIONAL AND RESEARCH INSTITUTEDr. M.G.R. UNIVERSITY(Estd. Under Sec. (3) of UGC Act. 1956.)1771650222885MINI PROJECT ON PHOTOSENSITIVE LCD MODULE CUM VISOR/DISPLAYSUBMITTED BY:-RISHI RAJ SAIKIA (081071101123)GAUTAM KAUSHIK DUTTA (081071101176) K. BIKRAM SINGHA (081071101184)<br />ABSTRACT<br />In the proposed paper we are going to demonstrate an advance controlling of transparent LCD.The system commencing this operation is named as PHOTO-SENSITIVE LCD MODULE CUM VISOR/DISPLAY (PSLVD). With the help of PSLVD a transparent LCD can be used both as light controlling visor as well as a multidisplay. This device on visor and multidisplay mode is controlled only by two separate comparator circuitry.<br />The LCD acts as a filter according to the light intensity in visor mode and as a intelligent display solution to mobile screens.<br />The above LCD can also used be switched into a display which will be readable during high sunlight also which will be done by active backlight adjustments and contrast adjustment. <br />The main blocks of the circuitry are-<br /><ul><li> Transparent LCD
Current limiting resistors.</li></ul>The advantage of the above system will be non hazardous driving(on application of LCD as windscreen), it can be used as window panes in corporate offices which will act as automatic llight controlling glass and in night time for advertisement purpose. <br />INTRODUCTION<br />In todays world the technology is changing rapidly evrything becoming more sophisticated and simple electric equipments are becoming electronic as they are more reliable and long lasting. In every aspect the things are changing rapidly electric to electronic even digital eg- the ignition of a car engine to the speed control of a fan. A smart car with the mentioned technology will have a better perfomance in other words driving will be less tidious and in hot weather the bright sun will not be a problem . A mobile screen implementing this technology will give a better performance .<br /> On implementation of PSLVD in mobiles , will make the display readable under the direct sun also. On application of this technology in Smart-Home will provide a automatic light controlled living room and thus making it more comfortable and cool in hot sunny weathers , also adding to the list, an economic way of keeping the room cool.<br />BLOCK DIAGRAM<br /> COMPONENTS:- <br /><ul><li>JHD 162A LCD - 1Nos.
RPS- 1Nos.</li></ul> Photo- sensitive LCD module cum visor/display<br /> THEORY:- An LDR is a photoresistive material which gives inverse response to the intensity of the light i.e the resisitance of the LDR decreases with the increase of the intensity of light . The relation between resistance(RL)and light intensity (LUX) is given by...<br />RL= 500/LUX kohm<br /> As shown in the figure the basic controlling circuitry consists of three comparators C1,C2 and C3...with voltage divider networks consisiting of Rx,Ry,Rz and x and another network consisting of LDR and 3 1-Kohm resistors. The X is the resistance of the LDR at ambient light conditions. As shown in figure inverting terminal of each comparator C1,C2 and C3 are connected after x,Rx and Ry respectively. Similarly the non inverting terminal of each C1,C2 and C3 are connected x,R1 and R2 respectively. The resistors Rx,Ry and Rz are potentiometers or variable resistors. The supply voltage Vcc is connected across both the divider networks<br />When high intensity light falls on the LDR the comparators C1,C2 and C3 produces high outputs according to light intensity<br />A DPDT switch holds the control of switching between display and visor mode...<br />In visor mode the controlling circuit 1 which is connected to the LCD becomes active and the LCD acts as an active light controlling element or filter. Inhigh intensity light the LCD goes more darker and prevents excessive light from enterimng through the LCD...<br />In display mode the controlling circuit 2..becomes active and the number of LEDs glowing changes according to the intensiy of light falling on display and thus making it more visible even in high intensity sunlight....<br />WORKING:- <br />In Visor Mode:- In visor mode when the high intensity light falls on the LDR ,the resistance of the LDR decreases. If the resistance becomes half the comparator C1 gives high output which makes the LED little dark. If the intensity is high enough to keep the resistance of the LDR in between x/2 and x/3 (where x is the resistance of the LDR at ambient light) comparator C1 only give output. If resistance becomes less than x/3 the comparator C2 will also produce high output along with C1 which will further increase the current and LCD will turn more dark. Similarly C3 will give output current along with <br /> <br />C 1 and C2 if resistance grow lesser than x/4. The above explanation can be summarised as......<br />Light IntensityComparator o/pResistance of LDRCondition of LCDLessC1,C2,C3-lowResistance=xTransparentMediumC1-highC2-lowx/4<Resistance<x/2Less DarkC3-lowHighC1-highC2-highx/20<Resistance<x/4DarkC3-lowVery HighC1-highC2-highResistance<x/20More DarkC3-highSource- mix....<br /><ul><li> In Display Mode:- In display mode the number of LEDs glowing increases in accordance with the intensity of light.Moreover the contrast of the display will change in accordance with light intensity which makes it more visible ; even in bright sunlight .Taking the light conditions as same as that of the visor mode, the working can be understood from the following tabulation. </li></ul>*NOTE- In display mode LEDs L series will always remain on.<br />Light IntensityComparator o/pResistance of LDRLED’s GlowingLowC1,C2,C3-lowResistance=xLMediumC1-highx/4<resistance<x/2L1,LC2,C3-lowHighC1-highx/20<Resistance<x/4L1,L2,LC2-highC3-lowVery HighC1-highResistance<x/20L1,L2,L3,LC2-highC3-highSource:- mix..<br />From the above two tables , on application of 9 volt battery as a source and x=8 kohm , we can easily deduce that ...<br /> Rx = 0.5 kohm<br />Ry = 1.5 kohm<br />Rz = 3 kohm<br /> CONCLUSION :- From the above discussion in the given paper and also from the hardware model it can be observed that:-<br /><ul><li>The PSLVD system is an economic advanced way display system.
It can be used as normal sun reflective glass as well as a smart display.
Its smart backlight adjustment system makes it more readable during bright day light.</li></ul> <br />