| 摘要 |
<p>Blackboards are used as one of the oldest teaching device in the world but with the modifications in the technology whiteboards are invented for eliminating the diseases caused by chalk powder. Now-a-days Whiteboards are used in most of the educational Institutes. Large size whiteboards give advantage of using more area for writing purpose but on the contradictory it is time consuming to nib the boards. Different methods of cleaning the boards have been developed. This led to the invention of self-cleaning whiteboards. Hence, many approaches are introduced to clean the board automatically. An attempt has been made to modify the features of automated motorized whiteboard by introducing a duster detaching mechanism. Due to this mechanism teacher can use the writings on the board as a future reference. The system consists of many small parts and mechanisms which are used efficiently for the working of the board. Some of them are: - Flexible whiteboard surface material, dusters, plastic rollers, cam and follower, four bar mechanism and motors. The working of this system is based on rotation of flexible whiteboard sheet material around the rollers. Rollers are operated by means of motors. In this way the whiteboard surface gets cleaned automatically by the dusters fixed on the backside of the board. If anyone wants to use writing for future reference then cam follower and four bar mechanism is used to detach the dusters from whiteboard. In addition to this a stand is designed to adjust the height of the board and also to make it portable. PARTS SPECIFICATIONS/ DIMENSIONS 1. DC Gear motor Speed-lOORPM Voltage-4V to 12V Stall torque-42.5 IKg-cm Stall current-6.9Amp Gear assembly-Spur Shaft length-25 to 30mm Shaft diameter-8mm 2. Wooden Block (Covered with sunmica sheet) Length-80cm Height-50cm Breadth-5cm 3. Rollers (PVC Pl astic) Diameter-5cm Height-40cm 4. Duster holders (Plywood) C Shaped Height-65cm Breadth-10cm Width-10cm Thickness-1.2cm 5. Dusters (Sponge) 1st pa ttern 2nd pattern 3rd pattern Length Breadth 28cm 3 cm 14cm 3cm 40cm 3cm 6. AC to DC Converter Voltage-12V Current-3A 7. White board surface Length- 19 Breadth-40 2cm cm 8. Cam and followers Outer diameter- 6 cm Inner diameter- 3 cm Type- Tangent cam 9. Springs Mean diameter - 20 mm Coil diameter - 1 mm 10. Stand Cross sections: 1. 2.56 cm 2. 3.175 cm 3. 3.81 cm</p> |
