Patent Application
20060187619
1. Field of the Invention
The present invention relates to an electrical connection box, and especially to an electrical connection box having protective features within its internal construction to provide safety and efficiency towards the operation of LED's (Light Emitting Diodes) connected to it.
2. Description of the Prior Art
It is well-known that current connection boxes have simple function of connection. Once a short circuit situation has occurred or the circuit temperature rises over the set protective limit, the circuit will be blocked off and the LED's will be burnt out. Although a fuse may be added in certain type of connection box, once the fuse has blown, the connection box becomes broken.
Thus, an improved electrical connection box which overcomes the above-mentioned problems is desired.
A primary object of the present invention is to provide an electrical connection box having protective function of offering safety and efficiency towards the operation of LED's connected to it.
To achieve the above-mentioned object, an electrical connection box in accordance with a preferred embodiment of the present invention is disclosed. The electrical connection box comprises a base cover having a plurality of first openings in both sides thereof; a top cover having a plurality of second openings in both sides thereof; a main PCB board; an input DC socket located on said PCB board; a plurality of output DC sockets located on said PCB board; a plurality of short circuit protectors located on said PCB board, each said protector connecting each said output DC socket in parallel; a thermal protector located on said PCB board; and a heat transmitter covering on said input DC socket, output DC sockets, short circuit protectors and thermal protector; wherein said heat transmitter concentratively transfers the heat of said input DC socket, output DC sockets, short circuit protectors to said thermal protector; and wherein said main PCB board, input DC socket, output DC sockets, short circuit protectors and thermal protector are arranged between said base cover and top cover. The present invention also provides a short circuit protector arranged in the electrical connection box comprising a triode; and a constant voltage diode; wherein the anode of said constant voltage diode connects with the collector of said triode and the cathode of said constant voltage diode connects with the base of the triode.
In accordance with the present invention, every series-connected socket has paralleled short-circuit protection. Once an LED short-circuit situation has occurred, individual short-circuit protection will activate and isolate the faulty LED fitting, but maintain the proper operation of the rest of the fittings connected to the electrical connection box. As soon as the cause of any short circuit has ceased, the short circuit protection will end and normal operation of the circuit resume. The electrical connection box also has a thermal protector connected across the whole circuit. If the electrical connection box circuit temperature rises over the set protective limit, this thermal protector will automatically cut off the whole power to all output circuits. When the temperature returns to a safe temperature, the power is automatically resumed to all outputs again.
Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Referring to
The input DC socket 4, output DC sockets 5, short circuit protectors 6, and the thermal protector 7 are soldered on the main PCB board 3 by soldering-tin. The input DC socket 4 is located on one end of the PCB board 3. In the preferred embodiment there are six output DC sockets 5. Three of these output DC sockets 5 are arranged along one side of the PCB board 3 and the other three sockets 5 are arranged along the other side of the PCB board 3. These output DC sockets 5 are connected each other in series. Each output DC socket 5 connects an LED load unit (see
Referring to
Then referring to
In general, the constant current output unit 61 has a maximum output voltage VOUTMAX, while the rated voltage of the LED load unit 9 which we use VLOADMAX is not excess of the maximum output voltage VOUTMAX, that is VLOADMAX <VOUTMAX.
When an LED load unit 9 works in a normal state, the voltage thereof is between 3˜3.7 V, while the voltage of the constant voltage diode DZ is 3.6V plus 0.6V of the on voltage of the base of the triode Q1. As a result, the on voltage of the constant voltage diode DZ is over 4.2V. In other words, no current passes the base of the triode Q1, that is, the triode Q1 turns off.
Provided that VOUTMAX is 40V and the rated voltage of each LED load unit 9 is 3.5V, the total load voltage VLOAD is 21V (3.5*6=21), here VLOAD is less than VOUTMAX. When an LED load unit 9 is broken and under an open circuit state, the output current will decrease to zero abruptly, while the output voltage of the constant current output unit 61 (namely the voltage of the short circuit protector 6) will increase rapidly from 3.5V. During the course of this voltage increasing, when it reaches over 4.2V (3.6V plus 0.6V), the constant voltage diode DZ will be activated and then the triode Q1 will also be activated for the reason of the current passing through the base thereof. This current flow by the triode Q1 and self-recovery temperature resistance RT, which makes the LED load unit 9 and the constant current output unit 61 a loop to keep on conducting. Here the temperature of the triode Q1 will rise gradually. Once this temperature is over a rated value of the self-recovery temperature resistance RT, the circuit will turn off and the temperature will drop subsequently. As soon as the temperature is less than the rated value of the self-recovery temperature resistance RT, the circuit will turn on accordingly. In this case, the normal LED load units 9 will be sometimes on and sometime off, so as to remind users to change the broken LED load unit 9.
When an LED load unit 9 is broken and its internal resistance increase, the current of the constant current output unit 61 keeps constant. So the voltage of the LED load unit 9 VLED increases too. When it is over 4.2V, as stated in aforesaid paragraph, the triode Q1 will be activated. Here the current will pass through the triode Q1 and the LED load unit 9.
When an LED load unit 9 is broken and under a short circuit state, the current goes through the LED load unit 9 directly. There is not any adverse effect on other LED load units 9 and the constant current output unit 61.
When changing an LED load unit 9, the output DC socket 5 connected thereto will switch on to short-circuit the protector 6 if taking off this LED load unit 9. The temperature of the circuit drops therewith. When a changed LED load unit 9 is on, the output DC socket 5 connected thereto returns to switch off. Because there is a little dithering when replacing the LED load unit 9, here the voltage of the LED load unit 9 is 3.5V and that of the constant voltage diode DZ is 4.2V, the triode Q1 is not be activated. Thus, it does not require cut off the power when changing the LED load unit 9. The operation is also simple and convenient.
It is believed that the present invention and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200520007221.8 | Feb 2005 | CN | national |
