US2262098A - Head lamp of motor vehicles - Google Patents

Description

HEAD LAMP OF MOTOR VEHICLES Filed Aug. 1'7, 1959 Q5716 1.9 .70 Cw w f INVENTC'RQ I E5 CIROOK IT,J.W.HE1GHWAY Patented Nov. 11, 1941 UNITED STATES HEAD LAMP F Moron VEHICLES Ernest William Crook and Tennyson James William Heighway, Hastings, New Zealand Application August 17, 1939, Serial No. 290,700 In New Zealand August 29, 1938 2 Claims.

This invention has been designed with the object of providing for the elimination of the glare effect attendant upon the use of the ordinary types of motor vehicle head lamps, and which effeet is directed upon the vision of the drivers of 5 approaching vehicles by reason of the beams of light from the head lampsbeing thrown upwardly above the level of the lamps.

The invention provides for its object being made and adjusted that in combination with. the ordinary parabolic reflector the beams thrown forwardly from both upper and lower halves of the reflector are directed below the the beams are contained within a semi-circle having its chord in the horizontal line of such centre. This is effected by imposing the beams of one half of the lamp upon those of the other centrated below the level of the lamp centre and thus while effectually illumining the path of the vehicle, are free from direct glaring effect upon the vision of those facing or approaching the lamps from the front who are at a higher level,

as'is the case with the drivers of approaching vehicles.

The invention consists in a novel construction or formation of the glass envelope of the lamp bulb so that when adjusted in a standardized position in the lamp as concerned with the relationship of the filament, or light source, thereof and the parabolic reflector of the lamp, the light rays from the filament in their passage to the reflector, are so controlled and directed that they strike the respective upper and lower halves of the reflector so, as to be projected through the lamp front, to form the composite beam of the nature before referred to.

To obtain this object, the well known prin-.

ciples of light refraction, obtained by the passage of light rays through prisms, is employed in the formation of the lamp bulb envelope. This may be effected by forming the bulb of such nature as to the two halves of its surface in relation to the horizontal axis of the bulb (when in position in the head lamp), so that one half is of prismatic nature while the other is plain, or both halves are of prismatic nature, and by so positioning the filament therein that when the bulb is placed within the ordinary holder in the lamp, the light rays are directed and controlled to obtain the beforementioned projection of the lamps beam.

For instance, the invention may be given effect those from the lower half. obtained by the employment of a lamp bulb so 10 by this invention.

to by forming the lamp bulb envelope as to its lower half of uniform thickness and as to, its

upper half of prismatic nature, and positioning the filament therein to provide that the rays fromithe lower half shall be projected forwardly below the axis level of the lamp and those from the upper half shall be refracted and projected downwardly and forwardly to join with Or, the upper half may be of uniform thickness and the lower half of prismatic nature and the filament positioned therein to get a similar projection of the rays from both halves. Or, still again, both halves maybe of prismatic nature. level of the lamp centre under a method in which 15 Also, it is desirable with such a bulb that provision should be made therein whereby the rays from the two halves that are thus. controlled should be clearly defined in their projection in order to get a straight top line for the joint half so that the whole of the beams are con- 20 beam, and whereby the light rays that are thrown directly forward from the filament shall be shielded or controlled to prevent interference with the main beam. -For these purposes the lamp bulb may have its filament holderso made as to cause the rays therefrom to be shielded in the horizontal plane of its thickness. In addition, the lamp bulb may be furnished in its front with a reflector that will receive the rays that would miss the parabolic reflector of the lamp and throw them back on to such parabolic reflector,'to be then directed in the line ofthe main beams.

' Fora fuller explanation of the invention, reference will be made to the accompanying sheet of drawing, in which- Figure 1 is a diagram showing in side elevation the lamp bulb and reflector and the manner of projecting the light beam provided for Figure 2 is a sketch showing the cross sectional form of such beam.

Figure 3 is an enlarged detail vertical sectional elevation of a lamp bulb made according to the invention and in its simplest form.

Figure 4 is a front cross sectional elevation thereof on the line 4-4 of Figure 3.

Figures 5, 6 and 7 are sectional elevations of respectively different forms of the lamp bulb.

Figures 8, 9 and 10 are views of diiferent forms of filament holders having the shielding property hereinbefore referred to.

In all the general principles and features of its construction, the lamp bulb A is made on common and well known lines. It difiers, however, from the lamp bulbs as usually made, in the formation of its glass envelope, whichis so shaped that when used with the ordinary parabolic reflector B of a head lamp assembly, the rays from the bulb are controlled and directed, as shown in Figures 1 and 2, to provide for those from the lower half of the reflector being projected forwardly in a horizontal line and in a beam of semi-circular cross section having its chord horizontal across the axis of the lamp, and those from the upper half being thrown downwardly and forwardly and reversed, to produce a beam that is coincident with that from the lower. half. Thus the whole of the light rays are concentrated into a single beam of full power, diverging horizontally but controlled so that it does not rise about the axis of the lamp.

In the form shown in Figures 3 and 4 this is effected by shaping the lamp bulbs glass envelope so that it is divided horizontally into two sections, the lower section C being made of uniformthickness and the upper section D being of the prismatic nature shown, under which its thickness increases from its front to its rear end. In vertical cross section the lower half is made to join with the greater thickness of the upper half, as in Figure 4. The filament E, of single form, is positioned in the bulb at a defined position to ensure that when the bulb is made with a standardized plug end and is placed in a standardized holder to occupy a definite relationship to the reflector B, the rays thrown out .through the lower half C are projected in the manner shown in Figure l. The prismatic upper half D is so made that under these conditions the rays passing through such half are refracted to the necessary angles to obtain the downward and forward direction also indicated in such figure.

The bulb may, however, have its filament so positioned that the same effects would be produced if the prismatic half is on the lower side and the uniform half uppermost.

Or, as shown in Figures 6 and 7, both halves may be of prismatic form but relatively reversed in the direction of their thickening and the filament positioned to obtain by the refraction of the rays paths the aforesaid control in the beams projection from both halves of the reflector B. All of these forms are capable of being standardized for practical use.

The front part F of the bulb may be made opaque, or otherwise treated to prevent, the direct spreading ofrays from the filament in a forward direction. Or, it may be silvered or made of reflecting nature to throw such rays back on to the projecting reflector. Or, if desired, these rays may be caught upon the surface of an inclined reflector G (see Figures and 7) positioned in the forward end of the lamp, and.

thrown backward to pass through the upper half of the bulb for direction downwardly from the upper half of the reflector B. This reflecting surface G must be so constructed and disposed that its bottom edge is below the horizontal plane of the lamp to the extent such as to cut off all rays that would miss the front of the lower half of the bulb. These ways of controlling or of cutting off the forwardly directed rays from the filament will aid the definition of the beams shape in the manner described.

Provision may, however, also be made to definitely divide the rays of the lower and upper halves one from the other so that the horizontal top edge of the projected beam will be the more clearly defined. This may be effected by constructing the filament holder in either of the ways shown in Figures 8 to 10 so that it is horizontally surrounded by a shield H of a width approximating to the thickness of the filament. A darkened shadow line is thus thrown on the reflector B, in a line horizontally across its axis to divide its surface area into two separate zones.-

While the prismatic formation shown in the drawings is of plain unimpeded type, it will be understood that in some cases, and for purposes of decreasing the weight of the bulb, the prism may be of stepped formation, without departing from the spirit of this invention.

We claim:

1. An electric lamp bulb for use in a motor vehicle head lamp having a parabolic reflector the axis of which is substantially horizontal comprising a cylindrical base adapted to be mounted coaxially of the reflector, a filament carried by the base, and a glass envelope carried by said base and surrounding said filament, said envelope having its lower half of uniform thickness and its upper half of varying thickness increasing in thickness from its forward to its rearward edges and from its side edges toward its middle.

' 2. An electric lamp bulb for use in a motor vehicle headlamp having a parabolic reflector the axis of which is substantially horizontal comprising a cylindrical base adapted to be mounted coaxially of the reflector, a filament carried by the base, a glass envelope carried by said base and surrounding said filament, said envelope having its lower half of uniform thickness and its upper half of varying thickness increasing in thickness from its forward to its rearward edges and from. its side edges toward its middle, and a light reflecting screen mounted at the forward porti'onof said envelope for reflecting rays of light falling thereon through the upper half of said envelope.

ERNEST'WILLIAM CROOK. TENNYSON JAMES WILLIAM HEIGHWAY.

Images