Design for Function and Marketability

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ENG 5142(2 semesters Team 2)

Report of Task 2
Product: Energy saving light bulbs

Ding ZheWei (Leader):11531492G
Leung Tsun Kin :12019613G
Li Yaxuan: 12127293G
Qiu Yi: 12126526G


Table of contents

Chapter 1 Working Mechanism3
1.1 Working Mechanism of Compact Fluorescent Lamp3
1.2 Working mechanism of ballast4
Chapter 2 Design of Compact Fluorescent Lamp Electronic Ballast6
2.1 The function of electronic ballast6
2.2 Circuit diagram6
2.3 Some factors about influence of working frequency of ballast7
2.4 Detail design of this project8
2.4.1 Driver IC - Compact FAN77108
2.4.2 Selection of Resistance9
Chapter 3 Light, Indicator & category of lamp13
3.1 Introduction of light13
3.2 Indicators about lamp:14
3.3 The category of lamp and their characteristics16
Chapter 4 Material of CFL20
4.1 Glass20
4.2 Fluorescent powder23
4.3 Filling gas28
Chapter 5 Safety and performance standard of CFLs30
Chapter 6 Model (2D & 3D) for our products35
Appendix 136
Appendix 237

Chapter 1 Working Mechanism
1.1 Working Mechanism of Compact Fluorescent Lamp
The conversion of electrical energy into radiant energy is relied on inelastic scattering of electrons inside the tube. Low pressure mercury vapor is injected into the tube. When the tube is connected to electricity, electrons emitted from the tube by the high temperature filament. The electrons moving in collide with the mercury atoms. Such collisions transfer kinetic energy in electrons to the mercury atoms. By absorbing this extra energy, the outermost shell electron in mercury atoms jump to a higher energy state, which is unstable to stay. A photon is emitted and this excited electron moves back to its original position. According to Planck’s law,

E = hc/λ

Where E is the energy of the photon carries, h is Planck’s constant, c is the speed of light and λ is the wavelength of the light emitted by the photon. The wavelength of the photons emitted is in ranges between 185 to 253.7 nm. Such a wavelength is within UV region in light spectrum and human cannot see such a light. This radiation is converted to visible light by usage of fluorescent. A layer of fluorescent is coated inside the light tube. When the UV photons pass through the fluorescent layer, a similar transfer of energy level occurs in the electrons in the atoms of fluorescent material. At this time, a photon with wavelength in visible light band may emitted, this gives out light to human.

When we connect the CFL to an electric source, the electric power heats up the filament inside the light and electrons are emitted from it. The accelerating electrons hit on some noble gas, which injected into light tube with a very small amount. The electrons firstly collide with the noble gas atoms, this form plasma as the noble gas is ionized by highly energetic electrons, known as impact ionization. The conductivity of the ionized gas increases and allows higher current passes through due to electrons avalanche. Electrons avalanche is release of additional electrons from impact ionization. Such an avalanche leads to a generation of large amount of electrons inside the lamp tube. The electrons are colliding with the mercury atoms and fluorescent material atoms respectively, generating visible light afterward. The color of light generated is depend on the gas used. Mercury vapor is used generally as it can generate white light after reactions mentioned above. Green light can be generated by carbon dioxide and red light can be generated by neon replacing mercury vapor [1][2]

Diagram 1 the working mechanism of CFL

1.2 Working mechanism of ballast
Ballast is essential to CFL due to the working principle of CFL itself. In simplified sentences, CFL works by discharging mercury inside the light tube to generate light. This cause a lot of electrons and ions...
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