Abstract: The projector-type head lamp for vehicles comprises a reflector having an optical axis, a lamp bulb operable as a light source, having a filament horizontally disposed in a direction perpendicular to the optical axis, and a convex lens disposed in an area defined by the light beam shaped by the rays of light reflected by the reflector and having an optical axis nearly coincident with the optical axis of the reflector. The inner reflecting surface of the reflector has a main reflecting area including a part of a spheroid having the first focus near the center of the filament as light source and the second focus near the center of the cut-off edge, at least parts of the main reflecting area located above or below the horizontal plane in which the optical axis lies and which define multiple largely slanted filament images on the screen being formed as sub reflecting areas having such reflecting characteristics as to shift the filament images horizontally.

Abstract: The projector-type head lamp for use on vehicles according to the present invention comprises a reflector formed by a concave mirror having two foci, light source disposed near the first focus of the reflector, and convergent lens disposed opposite to the reflector with the second focus of the reflector located at the intermediate position between the lens and reflector. The convergent lens has an optical axis which is also the optical axis of the reflector and a focus located near the second focus of the reflector. There is provided near the focus of the convergent lens a shade which has a cut-off edge nearly in contact with the optical axis to produce a shaped beam. The convergent lens is composed of a frontal surface defined by an aspherical plane and a back surface defined by a flat plane which is so inclined in relation to the optical axis as to be nearer to the focus of the convergent lens as it goes from the upper portion toward the lower portion.

Abstract: The method for forming Fresnel lens according to the present invention is such that a Fresnel lens comprising a body with a frontal surface having a plurality of annular Fresnel-type prism elements concentrically disposed thereon and a back surface formed substantially flat is formed from a molten sheet glass. The method comprises a step for preparing cavities of which the shapes are derived from inversion of the shapes of the plurality of annular Fresnel-type prism elements, a step of disposing the molten sheet glass on a stationary mold having a substantially flat surface, a step of pressing the molten sheet glass with a moving mold having the cavities to make a portion of the molten glass flow into said cavities, and a step of solidifying the molten glass and removing the moving mold thereafter.

Abstract: In the projector-type head lamp for vehicles according to the present invention, a discharge lamp having a single color temperature is disposed at one of the foci of the inside reflective surface of a predetermined geometrical shape. There is disposed at the other focus of the inside reflective surface a shade intended to shape the reflected light beam from the inside reflective surface. The light beam having been shaped into an appropriate shape by the shade is condensed and projected frontward through the lens. Since the light source is a discharge lamp having a single color temperature, these light beams cause no dispersion by the lens. Therefore, no colored zone is produced near the dark area of the luminous intensity distribution pattern projected frontward, that is located along the light-dark limit defined as the result of the cutting by the shade of the light beams.

Abstract: The projector-type head lamp assembly comprises a reflector having plural reflection surfaces different in reflection characteristics from each other. The reflector has disposed in the center of the reflection surface thereof a first reflection surface area extended horizontally; adjoiningly at the top and bottom, respectively, of the first reflection surface area a second reflection surface area extended horizontally; and adjoiningly to the second reflection surface areas a third reflection surface area extended horizontally. The reflection surface areas are composed of numerous fine surface elements smoothly continuous to each other.

Abstract: A projector type headlamp in which the reflecting surface of a reflector is not the surface geometically decided but composed of a great many minute face elements smoothly connected with each other and the orientation of each face element with respect to the optical axis is decided such that the light incident from a light source is reflected to the vicinity of a meridional image plane of a convex lens and a desired luminosity distribution can be obtained at the position of a shade. According to the headlamp, it is possible to control a distribution pattern so as to have a desired luminosity distribution and to utilize the light emitted from the light source effectively.

Abstract: The automotive headlight of projector type comprises a reflector, a lamp bulb as light source disposed near the focus of said reflector, a convex lens which projects frontwardly the light emitted from the lamp bulb, reflected by the reflector and then converged to a predetermined light collecting area, and a light transmitting means device through which the light is projected directly and frontwardly from the lamp bulb. The light emitted directly from the lamp bulb is positively projected frontwardly through the light transmitting device without passing through the convex lens. Therefore, the zones surrounding the illuminated zone are blurred. The luminous intensity of the zone near the boundary between the illuminated and non-illuminated zones can be gradually decreased going outwardly away from the projector axis into the non-illuminated zone without any influence on the illumination distribution of the zone illuminated by the light projected through the convex lens.

Abstract: A drive transmission structure for a tractor comprising a belt drive system for transmitting power from an engine output shaft to a transmission having a brake mechanism. The belt drive system includes a belt type stepless change speed mechanism having a split pulley assembly and a swing device for swinging the split pulley assembly toward the engine output shaft and the transmission, a first belt for transmitting the power from the engine output shaft to the split pulley assembly, and a second belt for transmitting the power from the split pulley assembly to the transmission. The pulley assembly defines two split pulley sections for engaging the first and second belts, respectively. A control device is provided to change power transmission ratios by actuating the swing device. Further, a tension pulley type clutch mechanism is provided to act on the first belt or the second belt. The brake mechanism and the tension pulley type clutch mechanism are controlled by the clutch and brake control mechanism.