Patent Application
20110013388
1. Field of the Invention
The present invention relates to a light string assembly, especially to a light string assembly using a reference diode to protect lighting units when an unintentional short circuit occurs.
2. Description of Related Art
With reference to
However, when a short circuit occurs in the light string assembly, the electric current will become too great for the resistor (63) and will overheat and damage the resistor (63) and the light emitting diodes (LEDs) (62).
To overcome the shortcomings, the present invention provides a light string assembly to mitigate or obviate the aforementioned problems.
The main objective of the present invention is to provide a light string assembly using a reference diode to keep lighting units from burning out when an unintentional short circuit occurs.
To accomplish the objective, the light string assembly has a plug, an extension socket, a light string, a resistor and a reference diode.
The plug is adapted to connect to an AC power. The light string is electrically connected between the plug and the extension socket and has multiple lighting units connected in series. The resistor is electrically connected to the light string in series. The reference diode is connected to the resistor in parallel in a reverse-biased direction. The reference diode avoids over-voltage across the resistor and thereby protects the resistor and the lighting units of the light string from damage.
Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
With reference to
The plug (10) is adapted to connect to an AC power and has a first contact (101) and a second contact (102).
The extension socket (20) is adapted to connect a plug of another same light string assembly and has a first contact (201) and a second contact (202).
The light string (30) is electrically connected between the plug (10) and the extension socket (20) and has a front terminal, a rear terminal and multiple lighting units (31). The front terminal is electrically connected to the first contacts (101, 201) of the plug (10) and the extension socket (20). The rear terminal is electrically connected to the second contacts (102, 202) of the plug (10) and the extension socket (20). The lighting units (31) are connected between the front terminal and the rear terminal in series and may be implemented as light emitting diodes (LEDs).
The resistor (40) is electrically connected to the light string (30) in series, may be connected to the front terminal or the rear terminal of the light string.
The reference diode (50) is connected to the resistor (40) in parallel in a reverse-biased direction and may be implemented as a Zener Diode. The reference diode (50) and the resistor (40) may be integrated with the plug (10) or the extension socket (20).
When a short circuit occurs, the reference diode (50) will maintain a fixed voltage cross the resistor (40) to avoid over-voltage and thereby protects the resistor (40) and the lighting units (31) of the light string (30) from burning out. Hence the light string assembly is safe. Furthermore, the resistor (40) and the reference diode (50) can be integrated with the plug (10) or the extension socket (20) to maintain an aesthetic appearance of the light string assembly.
Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
