In order to obtain a sufficient white LED beam, large-size LED chips have been developed in an attempt to achieve the desired goal in this way. In fact, when the electric power applied to the white LED continues to exceed 1W, the beam will decrease, and the luminous efficiency will be relatively reduced by 20% to 30%. The problems that must be overcome to improve the input power and luminous efficiency of the white LED are: suppressing the temperature rise; Service life; improved luminous efficiency; equalization of luminescence characteristics.

Increasing the power will reduce the thermal impedance of the white LED package to below 10K/W. Therefore, foreign countries have developed high-temperature resistant white LEDs in an attempt to improve the temperature rise problem. Since the heat of a high-power white LED is several times higher than that of a low-power white LED, even if the package of the white LED allows high heat, the allowable temperature of the white LED chip is constant. The specific way to suppress temperature rise is to reduce the thermal impedance of the package.

The specific method to improve the life of white LEDs is to improve the shape of the chip, using small chips. Since the light-emitting spectrum of white LEDs contains short-wavelength light with a wavelength lower than 450 nm, the conventional epoxy resin sealing material is easily destroyed by short-wavelength light, and the large amount of high-power white LEDs accelerates the deterioration of the sealing material. Switching to siliceous sealing materials and ceramic packaging materials can increase the lifetime of white LEDs by one digit.

The specific method for improving the luminous efficiency of white LEDs is to improve the chip structure and package structure to the same level as low-power white LEDs. The main reason is that when the current density is increased by more than 2 times, it is not easy to extract light from large chips, but the result will be The luminous efficiency is not as good as that of the low-power white LED. If the electrode structure of the chip is improved, the above-mentioned light extraction problem can be solved theoretically.

A specific method for achieving uniformity of luminescent characteristics is to improve the packaging method of white LEDs. It is generally considered that the above problems can be overcome by improving the uniformity of the phosphor material concentration of the white LED and the fabrication technique of the phosphor.

The specific contents of reducing thermal impedance and improving heat dissipation are:

1 Reduce the thermal impedance of the chip to the package.

2 suppressing the thermal impedance of the package to the printed circuit board.

3 Improve the heat dissipation of the chip.

In order to reduce the thermal impedance, many foreign LED manufacturers set LED chips on the surface of heat-dissipating fins made of copper and ceramic materials. As shown in Figure 1, the heat-dissipating wires on the printed circuit board are connected by soldering to the cooling fan. Air-cooled fins. The experimental results of the OSRAMOptoSemiconductorsGmb in Germany confirmed that the thermal impedance of the LED chip to the solder joint of the above structure can be reduced by 9K/W, which is about 1/6 of that of the conventional LED.

When the packaged LED applies 2 W of electric power, the temperature of the LED chip is 18 ° C higher than the solder joint. Even if the temperature of the printed circuit board rises to 500 ° C, the temperature of the LED chip is only about 700 ° C. Once the thermal impedance is reduced, the temperature of the LED chip is affected by the temperature of the printed circuit board. To this end, the thermal impedance of the LED chip to the solder joint must be reduced.

Conversely, even if the white LED has a structure that suppresses the thermal impedance, if the heat cannot be conducted from the LED package to the printed circuit board, the rise in the LED temperature will cause the luminous efficiency to decrease, so Panasonic has developed a printed circuit board and Package integration technology, the company encapsulates a square blue LED with a side length of 1mm on a ceramic substrate in a chip-on-chip manner, and then pastes the ceramic substrate on the surface of a copper printed circuit board, including the printed circuit board. The overall thermal impedance is approximately 15K/W.

Battery charging stations may be installed anywhere within the system where the production process allows the AGV to stop (staging areas, turn arounds, loading stops etc.).

A battery charging contact consists of a base plate, which is installed on the floor or laterally at a bracket adjacent of the AGV runway, and a current collector which is installed on the vehicle.

A Battery Charger supplies current to the base plate. Once the AGV is in charging position and the collector has made contact with the base plate, the AGV computer turns on the current.

The base plate has chamfered entry/exit ramps to facilitate smooth drive-on/drive-off of the spring loaded collector. 

AGV Charging Support

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Xinxiang Taihang Jiaxin Electric Tech Co., Ltd ,

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