Patent Application
20070013316
1. Field of the Invention
The present invention relates to a lampholder and a lamp string device and, more particularly, to a lampholder and a lamp string device having an automatic bypass device.
2. Description of Related Art
A lamp string is a device with several light bulbs series connected together to the same power source. The current flowing through each light bulb is the same. The sum of the voltage of each light bulb equals the total voltage of the power source. The lamp string is turned on if a complete connection of the electric circuit is achieved. If any one light bulb burns out, the integrity of the electric circuit is destroyed. The whole lamp string thus cannot be turned on.
When the above situation occurs, it is only necessary to link the gap of the light bulb that burns out to turn on the lamp string again. In the prior art, this is accomplished in a mechanical way. The total load resistance of the electric circuit, however, will drop, hence increasing the total current. The voltage across each light bulb will also rise, hence increasing the temperature of the filament. Therefore, it is easier for the remaining light bulbs to burn out. Basing on this inference, a vicious circle is inevitable. When the filament of light bulb reaches an upper limit of the tolerable temperature, a continuous burnout of light bulb will happen.
Accordingly, the present invention proposes a lampholder and a lamp string device having an automatic bypass device to avoid the occurrence of continuous burnout of light bulb.
An object of the present invention is to provide a lampholder and a lamp string device having an automatic bypass device. A diode is installed in each lampholder and is connected in shunt with the light bulb to span the same power source. Continuous burnout of light bulb due to an increase of the number of light bulbs that burn or get loose can be avoided.
Another object of the present invention is to provide a lampholder and a lamp string device having an automatic bypass device. The change time from when a light bulb burns out or gets loose to when the diode replaces its work is small, and the brightness changes little.
Another object of the present invention is to provide a lampholder and a lamp string device having an automatic bypass device, in which the characteristics of semiconductor devices such as small size, simple structure, and are fully exploited to lower the cost and save production material.
To achieve the above objects, the present invention provides a lampholder and a lamp string device having an automatic bypass device. The lampholder comprises a base and a diode. The base can fix a light bulb, and has two electrodes connected to a power source. The power source is used to turn on the light bulb. The diode is connected in shunt with the base to span the power source. The lamp string comprises several lampholders and several diodes. The lampholders are series connected together to a power source. Each lampholder can fix a light bulb, and has two electrodes connected to the power source. The power source is used to turn on the light bulbs. The diodes are located in the lampholders, and are connected in shunt with the lampholders to span the power source.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which:
The present invention connects a diode in shunt with two electrodes of a lampholder. When the light bulb burns out or gets loose, the two electrodes will be connected via the diode to avoid affecting other light bulbs on the same series-connected circuit.
As shown in
The lampholder 10 will be exemplified below with an AC power source. When the diode 14 is a bidirectional Zener diode, its breakdown voltage (6.8 V) is about 20% higher than the voltage (5.5 V) of the lampholder 10. If the light bulb on the lampholder 10 burns out or gets loose, the voltage across the two ends of the bidirectional Zener diode rises to the Zener breakdown voltage so that the Zener diode operates in the reverse region (6.8 V) to replace the role of the original light bulb, hence keeping the whole circuit intact.
As shown in
The present invention makes use of semiconductor diodes, which can be mass-produced and have a low price. The semiconductor diodes are suitable to ordinary lamp strings and low-price lamp strings. Moreover, the semiconductor diodes are small, and can be made in different shapes according to different applications. The semiconductor diodes can be installed in ordinary lamp strings that are slightly modified.
To sum up, the above diodes are connected in shunt with the light bulbs to the same power source to avoid the vicious circle of continual burnout of light bulb due to an increase of the number of light bulbs that burn or get loose. Therefore, the present invention can effectively solve the problem in the prior art that the lamp string is subject to the influence of part of its light bulbs. The present invention also provides an automatic connection mechanism without any mechanical movable part, hence having no trouble of bad contact. Besides, mass production can be accomplished, and the manufacturing cost is low.
Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and other will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.
