Black power saving: class D amplifier and LED backlight is the key technology

TV screen more and more, more and more large wattage sound, power consumption is also more and more big black appliances. Energy saving issues become increasingly prominent.

Appliance of the total energy consumption accounted for 15%, energy-saving appliances is a very important problem. However, such appliance object of concern at home and abroad are mostly white household appliances (air conditioners, refrigerators, washing machine, microwave oven, etc.) of black appliances (television, audio and other audio and video products) is rarely mentioned such problems. Only manufacturers play "energy saving" advertising, and no manufacturers hit "energy saving" advertising, do not need to save the black home appliances?

Black energy-saving problems

In fact, such black appliances at work is a very important part of energy saving, because black appliances in the daily working time is usually greater than the white goods working time.

The main energy black appliances consumption are located in the terminal part, is for the eyes to watch and display for ear horn. In principle, the larger the size of the screen, the more electricity, the louder the sound of the horn is more electricity. In recent years, the screen is more than 29 inches of the TV has become the best-selling TV products, the same wattage is higher than the number of 20 watts of audio is also welcomed by users. Whether it is CRT (CRT) display terminal or liquid crystal display terminals, the larger the screen, the more energy consumed. Similarly, in audio products, high-power audio amplifier, home theater and other energy consumption is also considerable.

China TV now has more than 410 million units, if each TV can save 10 watts of power, with a day watching 3 hours, every year can save 4 billion 500 million kwh. This is a very impressive figure. In recent years, the performance of black home appliances is getting higher and higher, the TV screen is bigger and bigger, the number of watts is increasing, and the power consumption of black home appliances is also increasing.

Black appliances how to use without reducing the performance, to achieve power saving?

CRT efficiency: the class D amplifier

China's 2007 production of 88 million 70 thousand TV sets, 70% of which is CRT TV, while China is now using the CRT monitor about 60 million taiwan. So CRT energy saving is still the most important issue.

The power consumption CRT is mainly determined by the size of the screen, the screen is bigger, the anode voltage is higher, the power consumption is also more. At the same time, the greater the deflection of the screen, the greater the need for the current, in the production of sawtooth scanning circuit, to take energy-saving measures or great potential.

Although sawtooth current vertical deflection required is completely determined by the angle, but the sawtooth of the same size, the required power can be saved. At present, almost all of the vertical deflection amplifier uses the AB amplifier to amplify the power of the vertical deflection sawtooth wave. But this kind of AB deflection amplifier works in the linear state, the efficiency is very low. Usually only 20%-30% efficiency at low output. Thus, the class AB amplifier requires a large radiator to heat.

Now appeared on the market a new type of class D amplifier, the amplifier stage power transistor to work only in the switch state, can make the analog signal amplification, the efficiency can reach 80%-90%. When the amplifier is applied to the vertical deflection amplifier, it can save a lot of energy. For example, a class AB deflection amplifier would require 6.94 watts, while using the D class deflection amplifier for as long as 2.94 watts, saving a power of 4 watts. And another larger screen vertical deflection circuit, the original need 10.8 watts, the use of class D amplifier, it needs only 4.6 watts, saving up to 6.2 watts. So, on average, in a TV vertical deflection using D class amplifier, you can save about 5 watts.

Although 5 watts is not a big number, but the number of current domestic CRT TV to reach 400 million units, the use of 3 hours a day on average, annual savings of 2 billion 190 million kwh of electricity. The use of CRT computer monitors the number of 60 million, assuming the use of 8 hours a day, a year can save electricity of 876 million kwh. The sum of up to 3 billion 66 million kwh, the number is very considerable.

LCD display backlight: start from energy saving

In China in 2007 the production of LCD TV 26 million units, of which, the domestic sales of more than 8 million units. LCD TV is the largest energy consumption in the backlight display.

LCD TV at present most of the cold cathode fluorescent lamp (CCFL) as the backlight. The luminous efficiency of CCFL is higher, but because of its light is emitted to the surrounding, the need to use a mirror to reflect the light emitted back, so it will lose a lot of. Moreover, the color performance is relatively poor, usually only NTSC (ie NationalTELevisionSystemCommittee, is the International Television Standards Committee for color television broadcast standards, expressed as a percentage. This indicator indicates the degree to which the display device can be displayed on a variety of colors (standard 70%-80%). And it's a bigger problem - environmental protection - mercury. The European Union's RoHS standard has stipulated that electronic products are not allowed to contain mercury. From the beginning of July 1, 2006 are not allowed to import, if imported to pay $10 of hazardous waste disposal fee.

The luminescence efficiency of LED is relatively low, only CCFL 2/3. However, this situation will change with the improvement of luminous efficiency of LED.