LED Taiwan

Common infrared LED that emits infrared rays has the same appearance with visible light LED. Its appropriate operating voltage is around 1.4v and the current is generally smaller than 20mA. Current limiting resistances are usually connected in series in the infrared LED circuits to adjust the voltages, helping the LEDs to be adapted to different operating voltages.

When using infrared rays to control correspondent unit, the controlling distance is in direct ratio with the emitting power. In order to lengthen its controlling distance, infrared LED should be operated under pulse state as the effective transmitting distance of the pulsed light (modulated light) is in proportion with the wind-induced current of the pulses. Thus, by increasing the peak value (Ip) of the pulses, the emitting distance of the infrared LED can also be lengthened. One way to increase Ip is to diminish the duty ratio of the pulse; that is to reduce the width of the pulse (T). The duty ratios of the working pulses for some color TV’s infrared remote controllers are around 1/3-1/4; and for some other electronic products, the duty ratios of the infrared remote controllers can even be as small as 1/10. Through reducing the duty ratio of the pulses, the emitting distance for small power infrared LED can also be increased in a large extent. Ordinary infrared LEDs can be divided into the following three types: small power one (1mW-10mW), medium power LED (10mW-50mW) and large power LED (50mW-100mW and above). The modulated light can be generated by adding pulse voltage with specific frequency on the driving diode.

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LED fluorescent lamp is the newest product line in the fluorescent family and is considered to be the final replacement for traditional fluorescent lamp. It is made up of white LED chip modules. Provided with the advantages of long life-span, radiation-free, energy saving, environmental friendly and stroboflash-free, LED fluorescent lamp is superior to other kinds of lamps.

Besides, the installation of LED fluorescent lamp is quite easy. Just to replace the original fluorescent lamp with the new LED one, and to take out the starter. What’s more, the electricity saving efficiency can reach as high as 50% compared to ordinary fluorescent lamp and the life span is more than 10 times than that of ordinary one, almost totally free of maintenance. LED fluorescent lamp is adaptive to be used in offices, factories, marketplaces, schools and houses and so on indoor spaces.

The following passages are going to sum up the advantages of LED fluorescent lamp.

1. Environmental friendly

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LED lumen attenuation is the weakening of the light signal during transmission. LED products made by global leading manufacturers at the present stage have lumen attenuation in different grades after used for a period of time and this phenomenon also exists in high power LEDs. Then, what causes LED attenuation? Lumen attenuation is directly related to the temperature, and is mainly determined by the chip, phosphor used and the packaging technology. At present, lumen attenuation has become the chief problem for white LED to march into civil lighting field. There are two main problems that cause LED lumen attenuation:

Ⅰ The quality of the LED product itself

1. The brightness of LED will attenuate quickly if the quality of the adopted LED chip is not good.

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LED luminous letter (or caption machine) adopts light emitting diode as lighting source. It is usually installed on the top of buildings or on wall surface in the shape of given letters or signs. LED luminous letter chooses high brightness LED chips and uses specific system to take control of the dynamic video of the letters or signs. The unique designed LED luminous letter surpasses the traditional outdoor advertisement in function. Its abundance colors make it much superior than traditional neon light and make break through in application variety. Meanwhile, the power-saving trait and long life-span of LED reduce maintenance and other cost for LED luminous letter in a large extent.

However, users will frequently be confronted with some problems in practical use. The following passage is going to sum up common problems in the use of LED luminous letters and the corresponding solutions for your reference.

Problem 1: Short life-span.
Although the theoretic life-span for LEDs produced by normal manufacturers can reach as long as 80,000 hours, a large number of LED luminous letters have to replace its LED modules frequently even less than one year’s usage. This will bring a lot of troubles and economic losses to customers and advertisement manufacturers.

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LED which is becoming widespread owns various kinds of product. LED products can be classified into different types according to light emitting colors, outer surface trait and structure of the diodes, luminous intensity, operating current, chip material, function and etc. This passage is going to introduce four types of LED products classification.

1. According to light emitting colors of the diode:

LEDs are available in red, orange, green (subdivide into yellow-green, standard green and pure green) and blue and so on.

Some light emitting diodes have chips that bear two or three colors. Besides, the package (the plastic body) of LED may have light scattering agent or not, be colored or colorless, thus, LED can also be classified into the following four types: colored transparent, colorless transparent, colored scattering and colorless scattering.

2. According to the outer surface (plastic body) traits of the diode, LED can be classified into round LED, square LED, rectangular LED, surface LED, side LED, surface mount subminiature LED and so on.

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LED brightness can be improved through the following two methods:

1. To increase the light output of the chip itself: light output can be increased through improving the luminescence efficiency of the chip’s active layer or improving the external light extraction efficiency by optimizing chips’ shape or making larger scale chips that run high density current.

2. To use the light effectively. In other words, to increase the amount of light that irradiate towards the needed direction. In this method, light wave control technology is used. Through a better design of the optical structure shaped by the packaged epoxy resin, the light can be controlled to shine towards expected direction, thereby improving the brightness of LED.

The above are the methods to improve LED brightness, if the brightness of LED display runs under expectation, methods listed below can be adopted:

1. To alter the current magnitude that runs through the LED. Generally, LEDs allow a 20 milliampere operating current continuously. Only red LED has saturation phenomenon, other LEDs’ brightness are in direct ratio with the current amount that runs through them.

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LED is the acronym of Light Emitting Diode. It is a kind of semiconductor device that is commonly used in indicator light and display board. LED is capable of transforming electric energy into light energy directly in high efficiency and its life-span can reach as long as tens of thousands hours to one hundred thousand hours. Compared to traditional bulbs, LED also bears the advantages of non-friable and power-saving and so on.

However, only well-packaged LEDs can be applied as terminal products in practical use. And the packaging types should be designed according to the requirements of each distinct type of LED.

Firstly, we need to figure out why should LEDs be packaged?

Through packaging, outer leads can be linked to the electrode of LED chips, thereby to protect the chips and to improve its luminescence efficiency. More important than the electrical signal output function, packaging makes sure that the diode chips to operate normally and to export visible light successfully. So the packaging is not an easy job as electric parameters and optical parameters requirements should be count on at the same time when doing the design.

Secondly, the packaging equipments used will be introduced here.

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Alone with the extensive application of LED in every trade, high power LED is widely adopted as light sources in traffic, railway and electronic equipment signal lamps. As defined by its name, high power LED is provided with higher power and heat, with larger lumen than ordinary LED, thus enable it to shine brighter. Strict requirements are posed on the selection of high power LEDs used in signal lamps. Ordinary LED can not be used as signal lamps at random for the following reasons:

1. Ordinary LED generally adopts epoxy resin as the fixing board; while high power LED needs to use MCPCB.

2. Ordinary LED can use wave soldering machine or handmade soldering, while high power LED needs to use surface mount technology (SMT) soldering machine.

3. Surface mounting devices (SMD) need to be used as matched electronic devices in high power LED.

4. As high power LED adopts surface mounting technology, realizing the highly integration of its electronic devices, thus the amount of lamps board and power supply can be small. This is what ordinary LED and its matched devices can not achieve.

5. Ordinary LED bears lower power and heat, but its heat tolerance performance and heat dissipation effect is not as good as high power LED. As to high power LED, although it is comparatively concentrated, its devices are fixed on MCPCB through surface mounting technology, making the adding of radiator easily.

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Nowadays, LED products are being used in numeric displays and indicator lights to a range of new and potential new applications, including exit signs, accent lights, task lights, traffic lights, signage, cove lighting, wall sconces, outdoor lighting and downlighting.

The following is the list of LED applications:

• Streetlights
• Large scale video displays
• Architectural lighting
• Status indicators on all sorts of equipment
• Traffic lights and signals
• Light source for machine vision systems, requiring bright, focused, homogeneous and possibly strobed illumination.
• Exit signs
• Motorcycle and Bicycle lights
• Toys and recreational sporting goods, such as the Flashflight
• Railroad crossing signals
• Continuity indicators
• Flashlights, including some mechanically powered models.
• Emergency vehicle lighting

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At present, three kinds of reading lamps are commonly seen in market: the traditional incandescent reading lamp, the halogen reading lamp and fluorescent reading lamp.

The incandescent reading lamp and the halogen reading lamp are cheap and emit the light with good continuity, yet they consume much energy and produce heat. If the power is high, they shine too much to make people dazzle; if the power is too low, the intensity of illumination is lower than requested.

The fluorescent reading lamp has a larger light pane, thus the shadow of the object which is shed on by the light is very small, which causes little impact on our eyes. However, the color rendering index of fluorescent reading lamp is lower and its frequency-flicker effect is inclined to make our eyes feel tired.
Lumps which contain mercury should not be abandoned like daily trash when they are used up. They should be collected and handled according to the relevant regularity. Some countries have made the law regarding this issue.

Currently, the market of high power LED reading lamp is still a burgeoning one; the price is high and customers know little about it. Nevertheless, LED reading lamp enjoys a vast market prospect. LED reading lamp has many advantages, such as eye-friendly, power-efficient, environment-friendly and lasting.

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