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2009-2010 F.2 Project Learning Project Presentation. Clean Door Knob. Chow Tung Yee (4) Wong Lai Ying (17) Lau Hin Chung (31) Li Wing Mun (32). Introduction.
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2009-2010 F.2 Project LearningProject Presentation Clean Door Knob Chow Tung Yee (4) Wong Lai Ying (17) Lau Hin Chung (31) Li Wing Mun (32)
Introduction Nowadays, Swine Flu rage(肆虐) in Hong Kong and toilet is the most dirty place. There are many germs on the toilet door knob because it has been touched by many people. Therefore we want to prevent the Swine Flu by makingthe knob always clean. We use three main instruments to invent our invention (reed switch(磁制), UV tube(紫外光殺菌光管) and timer) Reed switch is used to control the circuit. UV tube is used to kill the germs. Timer is used to control the power supply of the knob.
Aim Many people after using the public toilet ,they will clean their hands and leave. Since the knob is used by many people so there are many germs on the surface of the knob. When they touch the knob and leave, the germs will attach(依附)their hands. Thus their hands will become dirty again. Therefore, we want to keep the knob always clean.
Background information 1. Reed switch • The reed switch is an electrical switch operated by an magnetic. • It consists of a pair of metal reeds contacts made of iron in a sealed glass covering. The contacts will be normally open, or normally closed when a magnetic field(磁場) is applied. • The switch will be connected by putting a magnet near to the • switch, the switch will be closed. • Once the magnet is pulled away from the switch, the reed • switch will go back to its original position.
Reed switches are widely used for electrical circuit control. • Reed switches can be disabled by a strong magnetic field. • The glass covering of the contacts protects them from dirt, • dust, and other particles. • Function of the reed switch in the invention • There is a magnet placed under the door knob, the reed switch • will be connected and close the circuit when the magnetic field • of the magnet applied. • When the circuit is closed, the UV tube will light up. • When the magnet moved away from the reed switch by twisting • clockwise or anti-clockwise, the two reeds depart from each • other. The circuit is broken and the UV tube will turn off, it can • avoid our hands irradiated by the UV tube directly.
2. Ultraviolet light • UV light is found in sunlight • It can cause chemical reactions, and causes many substances to • glow • UV light can cause sun burn, but it has many other effects, both • favorable and damage on human health. For example, • -Security • -Astronomy • -Hunting • -Hygienic • -Chemical markers • In our invention, we make use on the hygienic function of UV light. • Hygienic function of UV light in the invention • Since germs that remain on the surface of the knob may not be • properly killed by regular cleaning. However, UV light can detect • and remove them all the time.
Apparatus: Apparatus & Materials Electric drill Hot glue gun digital multimeter A tool used for drilling holes in various materials. A tool used to stick things together. An electronic measuring instrument that can measure resistance, current and voltage.
Apparatus: Screw driver Wire-stripping pliers Cutter It is used to cut and remove insulation on electrical wires. It is a tool for the tightening of screws. It is used to cut things. Scissors Scissors are hand-operated cutting instruments. Used to cut things.
Materials: UV tube and wire Electric plug Wire connectors Magnet Fixer Reed switch
Materials: Insulation Tape Timer Knob Tinfoil board Electric wires woodblock
Procedure The left one is our old design, and we think that it is unable to work effectively. Therefore we change our design to the right one.
1. Use the hot glue gun to fix the reed switch on a piece of card and cover it with another piece of card.
2. Connect each side with wire one connector and use the hot glue gun to fix the position and use it as a insulator.
Connect the two sides of the reed switch with live and neutral wires from the plug respectively.
4. Connect the live and neutral wires of two UV tubes together to the corresponding wires of the reed switch.
6. Use the hot glue gun to stick the reed switch on to the woodblock.
7. Use the hot glue gun to stick the woodblock under the knob.
9. Use the fixer to fix all the too long wires on the bottom of the knob.
10. Connect the metal part of two UV tubes with green wires and join them to the earth wire of the plug, it is earthing. After that, put the green wire in to the fixer on the bottom.
11. Use the insulation tape to coil the connectors in order to avoid us from electric shock.
12. Stick the two tinfoil boards on the top of the UV tubes in order to make the UV light focusing on the knob.
13. Pull on the plug on the timer and pull them in to the socket.
How to use 1. When you want to leave the toilet, twist the knob clockwise or anti- clockwise.2. Open the door and leave the toilet.
Advantages & Disadvantages Advantages 1. Ultraviolet tube can kill the germs easily, effectively and automatically. 2. It does not produce any waste (compare to our old design, we use many tissue). 3. This invention makes people's hands always clean and it is convenient Disadvantages 1. Waste energy (open it for at least 12 hours and turn on & off all the time). 2. When the UV tubes open for a long time, it may become hot and people may get hurt easily especially children.
Product testing We tried to turn on and off the UV tube by twisting the knob, we find that after turning it 17 times, the reed switch becomes magnetized. Improvement • Use a reed switch with higher quality. • Covering the UV tube with transparent substances.
