With the technological innovation of LED products, LED Lighting has been widely used in lighting fields such as home, office and public facilities construction. As a special feature in the field of traditional lighting, straight tube type lamps have a high market share. Under the large-scale development trend of LED lighting products, the research and development of straight tube type LED tubes is also in full swing. This paper introduces a design of an LED tube that can replace the traditional lamp. Through mass production verification, the process is simple and reliable, and can be promoted and applied. This product can replace the traditional straight tube. Fluorescent lamps have a broad market prospect.
1. Classification and characteristics of straight tube LED products
1.1, product structure characteristics classification
From the characteristics of tubular structure, the most common straight-tube LED products on the market currently have the following categories: 1 semi-aluminum semi-plastic; 2 plastic-clad aluminum; 3 full-plastic; 4 full-glass tube.
1.2, the characteristics of all-glass LED straight tube lamp
All-glass straight tube LED has its own characteristics: the shape is consistent with the traditional T8 (T5) light source, the light color is soft, the light effect is high, the replacement is convenient, etc., and the acceptance in the market is getting higher and higher, the market share It is also steadily rising. At present, although the glass straight tube type LED has a certain market share, it can directly replace the traditional fluorescent lamp, and there are not many products directly in the original fluorescent lamp. We design and manufacture a kind of appearance and traditional straight based on the convenience of replacement. Consistent LED tube.
2, LED lamp design
In combination with the shape of the traditional fluorescent lamp, the replacement LED lamp component is divided into: drive design, housing glass selection, plug lamp head, and light emitting device.
2.1, drive circuit design
The drive circuit is the key to the design of the replacement LED tube, and the circuit is connected to simulate the filament of a conventional fluorescent lamp. The drive power consists of a main circuit for buck current limiting, rectification and filtering, and an analog filament resistor circuit with normally lit LED tubes and protected LED tubes from transient high voltage surges. The design includes an overvoltage and overcurrent protection circuit for preventing the lamp from being damaged due to excessive current and/or excessive voltage, a frequency detecting circuit for generating an induced voltage only when the high frequency current is input, and a low frequency alternating current or a high frequency. The BUCK step-down circuit that converts the alternating current into a clutter-free direct current rectifying and filtering circuit and a direct current for rectifying and filtering the output of the filter circuit to obtain an operating voltage of the LED bead group in the LED fluorescent tube, for shielding the said The PWM switching circuit in the BUCK step-down circuit is used to directly control the high-frequency straight-through circuit of the BUCK step-down circuit; the input end of the over-voltage and over-current protection circuit is connected to the output of the city low-frequency alternating current or electronic ballast a high frequency alternating current, wherein an output end of the overvoltage and overcurrent protection circuit is connected to an input end of the frequency detecting circuit, and an output end of the frequency detecting circuit is connected to an input end of the rectifying and filtering circuit, The other output end of the frequency detecting circuit is connected to the input end of the high frequency through circuit, and the output end of the rectifying and filtering circuit is connected to the BU The input end of the CK step-down circuit is connected, the output end of the high-frequency straight-through circuit is connected to the control end of the BUCK step-down circuit, and the output of the BUCK step-down circuit and the LED lamp in the LED fluorescent tube Beads are connected. The drive line is as shown in Figure 1.
2.2, LED tube performance requirements for glass tube
Straight tube type LED lamp housing glass tube performance mainly includes appearance effect, light transmittance, atomization degree, temperature and humidity resistance, moisture resistance, hardness, electrical conductivity, expansion ratio, bending degree, and parameters for lighting color influences.
The key indicators are as follows:
1 Appearance effect: the color is generally milky white, the surface is smooth, no bubbles, no scratches, no noise, etc.;
2 Transmittance: test calculation method, using the same illuminating light source to apply the same specification of transparent glass tube and milky glass tube under the specified voltage power, test the photoelectric color parameter test with the integrating sphere, milky white and transparent light effect The ratio is the light transmittance, and the light transmittance is usually required to be 92% or more;
3 atomization degree: the matched light source (light bead) device is placed in the glass tube, the lamp is lighted under the rated voltage and power, and the luminous point (light bead) is not seen, and the whole glass tube is required to have uniform atomization degree and illumination. Uniform performance, no obvious difference between light and dark;
4 temperature resistance: the glass tube is placed in a 150 ° C high temperature box, after 200 hours, no color change, no burst, no deformation and other abnormalities;
5 water resistance: the glass is placed in a 60 ° C constant temperature water bath, after 24 hours, no color change, no burst, no deformation and other abnormalities;
6 expansion coefficient fluctuation: the expansion coefficient of the same batch of glass tube fluctuations required to be controlled at ± 1 & TImes; 10-7 / ° C;
7 Conductivity: the inner and outer walls of the glass tube are required to be non-conductive;
8 light color effect: the milky white glass tube and the transparent glass tube sleeve are tested with the same light source to test the light color parameters, and the spectrum, color temperature and color rendering index cannot be significantly different;
9 Hardness: Take T8 glass as an example. The general pressure of the general glass pressure gauge is more than 300N. The specific manufacturer's customer shall prevail.
10 Bending degree: Take the glass tube of T8-1.2 m length as an example. Generally, the bending degree is not more than 3°.
Among the above performances, the effects of light transmittance, atomization degree, temperature and humidity resistance, and light color are more important for most manufacturers.
2.3, lamp design
The replacement LED tube mainly consists of: plug 1, end circuit board 2, power drive, illumination module 3, and outer casing glass tube 4. The light-emitting module has a substrate material and a patch-type LED lamp bead, and the LED lamp beads are evenly distributed in the middle portion of the substrate. As shown in Figure 2 below
3, LED glass tube production plan
3.1. Difficulties in the process of mass production of LED tubes
Under normal circumstances, the light-emitting device and the glass tube in the glass tube are bonded by glue. First, there is difficulty in curing the glue. The glue in the production process of LED glass tube is generally silica gel, which takes a long time in the curing process, which increases the number of product turnovers in the whole production process, and the fluency in the connection process of each production link is affected, and the production efficiency is low. Second, in the production process of LED glass tubes, the fixing of PCBs and the installation of plugs require the completion of dispensing equipment. At present, the process development of dispensing equipment is becoming more mature and the process difficulty is relatively small; In the whole installation process of the LED tube, the power supply and plug installation are the most complicated, and the resistance to the flow of the operation is the greatest.
3.2, lamp tube production process automation program considerations
In order to solve the related problems existing in the LED production process and realize its systematic flow production operation, it is necessary to concentrate on solving the problems in the above production process. Moreover, the discussion on the automation scheme of the LED glass tube production process should also be carried out as the focus of work. The automation process plays a role in reducing the cost and improving the production efficiency in the production process of the LED glass tube. In the relevant production process, each enterprise The introduction of automation technology has made corresponding regulations. Among them, the introduction of automation must simplify the production process, fix the product structure, and ensure the substantial increase in product production. Therefore, in the process of introducing automation technology and improving product output, it is necessary to follow the process of fixing the product structure and simplifying the production process.
4 Conclusion:
This paper briefly describes the design scheme of a fully-replaceable LED glass tube, and analyzes the technical difficulties. It proposes to solve the technical difficulties by using analog filament resistance design lines and lamp bead optimization arrangement, and also proposes the use of automation points. Glue, automated assembly process program, in order to optimize LED glass tube design, process program, has a certain guiding significance for the mass production and promotion of LED glass tube.
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