SWITCHING DEVICE FOR SELECTION OF HIGH LIGHTS / LOW LIGHTS FIELD OF THE INVENTION This invention relates generally to a switching device for the selection of high / low beam lights, more particularly it relates to a device for controlling the distance between a source of light from a reflector, in order to select high beam / low beam from the front lamps of a car. BACKGROUND OF THE INVENTION The projecting distance of a front lamp of a car, is adjustable when switching its high / low beam, according to the condition of the road, particularly at night. A conventional front lamp is equipped with two sets of tungsten filaments in a bulb, including a first unprotected set and a second set partially protected. When the first set of tungsten filaments is turned on, all of its light is projected completely onto a concave arcuate surface in the front lamp and reflected as a beam of light to project further forward. On the other hand, when the second set of tungsten filaments is ignited, only a part of unprotected light is projected onto the concave arcuate surface and reflected as a low beam, to project relatively nearer. The conventional front lamp can be switched basically between a high and low beam by using a single bulb in the front lamp, although its intensity is more or less not strong enough, in this way some high-level cars are adapted with a pair of bulbs of discharge high pressure comprising an air-tight light discharge vessel and a
gas filler that includes a metal compound and a rare gas element, where the metal compound evaporates under normal conditions to decompose and release xenon particles for light emission. However, as the pair of high-pressure discharge bulbs is sealed in a closed container, it is impossible to switch the front lamp between high / low beams, and therefore each front lamp must be equipped with a set of beam bulbs high and low that involve more expense and reduce the internal space of the car. In view of the aforementioned imperfection, the inventor provides a switching device for selecting a high / low beam of automobile head lamps, wherein each front lamp contains only a high pressure discharge bulb. COMPENDIUM OF THE INVENTION The primary objective of this invention is to provide a switching device for high / low beam selection, wherein a determined electromagnetic valve is electrically activated to generate electromagnetic force to attract a bulb base in a lamp shield, for in this way changing the distance between a lighting element and a reflecting surface and obtaining the high / low beam switching effect of a front lamp. In order to achieve the aforementioned objective, the switching device for high / low beam selection of this invention, has the bulb base arranged in the lamp shield to accommodate the lighting element, wherein the bulb base is connected with the electromagnetic valve, which switches off or on electrically to shorten or lengthen the distance between the
lighting element and the reflective surface and in this way regulate the beam of high light or the low light of the front lamp. For more detailed information regarding the advantages or features of this invention, at least one example of a preferred embodiment will be elucidated below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The drawings related in condition to the detailed description of this invention that will be made subsequently, are briefly described as follows, wherein: Figure 1 is a sectional section view of this invention; Figure 2 is a schematic view showing the action of this invention in Figure 1; and Figure 3 is an exploded view showing components of this invention in three dimensions. DETAILED DESCRIPTION OF THE INVENTION As illustrated in Figures 1 to 3, a "high / low beam select switching" device of this invention comprises at least: an enclosure 1, a bulb base 2, a lighting element 3, a electromagnetic valve 4 and a lamp protector 5. The lamp shield 5 contains a concave ate reflective surface 51 and a hollow cylindrical end 52. The enclosure 1 is composed of two corresponding halves wherein each half of the enclosure 1 has a plurality of slots guide 11 on its inner wall in corresponding positions.The bulb base 12 is arranged to support the lighting element 3, which can be a high discharge bulb.
pressure or a tube or bulb of arbitrary lighting. A plurality of projecting rods 21 is formed in the outer wall of the bulb base 2 in corresponding opposite positions and is freely movable in and on effective guide grooves 11, wherein two projecting rods 21 in opposite positions are additionally connected with a lever. link 22 respectively and one end of the link levers 22 is commonly joined with an interactive arrow 23. The electromagnetic valve 4 is located within the enclosure 1, wherein a pulse arrow 41 is connected to the interactive arrow 23. By taking advantage of the above-mentioned architecture, the electromagnetic valve 4 is electrically ignited to generate electromagnetic force to attract the impulse arrow 41, to withdraw backwards and the bulb base 2 is pulled back by the link or articulation levers 22 (shown in the figure 2). During the movement of the bulb base 2, the projecting rods 21 also move in the guide grooves 11 to prevent arbitrary rotation of the bulb base 2, such that the distance between the lighting element 3 and the reflecting surface 51 it is shortened to allow the reflecting surface 51 to be used for a high beam source that can project light much farther. In contrast, when the electromagnetic valve 4 is electrically shut off, an internal spring member (not shown) will release the impulse arrow 41 and allow it to advance such that the bulb base 2 is restored (as illustrated in the Figure). 1) by the interactive arrow 23 and the link levers 22, to result in an elongated distance between the lighting element 3 and the
reflecting surface 51 to serve as a low beam source that projects light closer. In the above described, at least one preferred embodiment is illustrated in detail with reference to the accompanying drawings, and. it is apparent that numerous variations or modifications may be made without departing from the spirit and actual scope thereof as set forth in the following claims.