Patent Application
20080293290
1. Field of the Invention
The present invention relates to an extension cord and, more particularly, to an extension cord using an LED as an indicator lamp for indicating on/off of the extension cord.
2. Description of the Related Art
Conventional extension cords have various specifications in length and generally include a plug on an end and a socket casing on the other end for conveying AC electricity. In use, the plug of an extension cord is coupled with a socket of an external AC power source whereas a plug of an electric appliance or the like is coupled with a socket of the socket casing such that the electric appliance can be empowered by the external AC power source through the plugs and the sockets. A user of the electric appliance is often not aware of the existence and on/off state of the extension cord. A small neon lamp is provided on the socket casing and turned on to show the extension cord and to indicate that the power is on. However, the life of the neon lamp is only about 30,000 hours, and the neon lamp can only be perceived from a short distance when used outdoors in the night. The distance of perception of the neon lamp is even shorter when used in the daytime, and perception of the neon lamp is almost impossible in foggy or snowing areas.
An objective of the present invention is to provide an extension cord using an LED (light-emitting diode) as an indicator lamp for indicating on/off of the extension cord, allowing both indoor and outdoor use. LED has a life up to 100,000 hours and consumes little electricity. Furthermore, LED is small in size and has various colors suitable for various kinds of weather conditions and circumstances. Thus, a user can perceive the on/off state of the extension cord.
An extension cord according to the preferred teachings of the present invention includes a cable including a plurality of conductive wires and an outer coating that sheathes the conductive wires. A plug is formed on an end of the cable and includes a first insulating body and a plurality of prongs supported by the first insulating body and electrically connected to the conductive wires. A socket casing is formed on the other end of the cable and includes a second insulating body and a plurality of conductive plates mounted in the second insulating body and electrically connected to the conductive wires. A lighting device is mounted in one of the first and second insulating bodies of the plug and the socket casing. The lighting device includes a light-emitting diode (LED) electrically connected in parallel to the conductive wires and a DC converting circuit electrically connected to the LED. The DC converting circuit is adapted to convert an AC voltage from the plug into a DC voltage supplied to the LED for lighting the LED. Light beams emitted by the LED transmit through one of the plug and the socket casing to show the extension cord and to indicate on/off state of the extension cord.
In an example, the LED is embedded in a light-transmittable housing of the first insulating body of the plug.
In another example, the LED is embedded in a light-transmittable housing of the second insulating body of the socket casing.
In a further example, each of the first and second insulating bodies includes a light-transmittable housing in which an LED is embedded.
In still another example, the outer coating of the cable is light transmittable, and the cable further includes an optical fiber mounted inside the light-transmittable outer coating and electrically connected to the LED such that the optical fiber is lit by the light beams emitted from the LED to show the cable.
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
Of more importance, the extension cord according to the preferred teachings further includes a lighting device having an LED (light-emitting diode) for indicating on/off state of the extension cord. In an example shown in
The LED 41 can be constantly lit or flicker according to product needs. Furthermore, the LED 41 may emit red light to increase penetrability, to avoid scattering, to enhance perceptibility, and to enhance visibility, allowing use of the extension cord in foggy or snowing areas. The LED 41 has a long life up to 100,000, consumes little electricity, and is small in size. LEDs emitting other colors would be within the skill of the art.
By embedding an LED 41 in at least one of the plug 20 and the socket casing 30, the socket extension according to the preferred teachings of the present invention can be used both indoors and outdoors. LED has a life up to 100,000 hours and consumes little electricity. Furthermore, LED is small in size and has various colors suitable for various kinds of weather conditions and circumstances. When the LED 41 is lit, it is an excellent indicator lamp such that a user can easily perceive the on/off state of the extension cord. Furthermore, the cable 10 of the extension cord can be shown by embedding an optical fiber 50 in the cable 10 and electrically connected to the LED 41.
Although specific embodiments have been illustrated and described, numerous modifications and variations arc still possible without departing from the teachings of the invention. The scope of the invention is limited by the accompanying claims.
