Ichikoh Industries, Ltd.

Nissan Motor Company Limited

Yutaka Nakata

Hirokazu Yoneyama

Hirofumi Yamagishi

Kouji Shigemura

Mototsugu Yamashita, Deceased

Tooru Segoshi

A shape of a vertical cross section and a shape of a horizontal cross section in a lens are formed in a recess shape. Accordingly, even when a prism is not formed, a light transmitting through the lens is largely refracted and an interior section is hard to be visible. As a result, it is not necessary to finish a surface of a reflection surface of a reflector so as to have an optical performance equal to or more than an optical performance required for reflection with taking an appearance into consideration, and a working operation can be easily executed in comparison with the conventional one.

Lamp device for vehicle

A lens has a concave shape or a convex shape in either vertical cross section or transverse cross section. Thereby light passing through the lens is largely refracted and the interior is harder to be seen even if a prism is not formed. As a result, there is no need to give a finish more than optical performance required for reflection to the front surface of the reflecting surface of a reflector, which is for the purpose of enhancement of its appearance, and thereby the machining work is simpler than the conventional way. Further, since the lens has a flat shape in either vertical cross section or transverse cross section, the lens is easily polished when it is made of glass, which is excellent in manufacture of the lens.

Lamp device for a vehicle having a free curved surface and a lens without a prism

A headlamp that is installed at the front of an automobile, such headlamp including a light source, a main reflector, and a sub reflector. When the light source is turned on the headlamp reflects the light from the light source with the main reflector and the sub reflector to illuminate a road surface in a target luminous intensity distribution pattern, and chances the luminous intensity distribution pattern by moving the sub reflector. The main reflector and the sub reflector are prepared based on a composite combination of reflection surfaces of free curved surfaces. The sub reflector is movably disposed at a position where the light from the light source is directly incident to the sub reflectors and also at the position where the sub reflector does not interrupt a light path through which the light from the light source is incident to the main reflector.

Automobile headlamp having a main reflector and a movable sub-reflector

A shape of a vertical cross section and a shape of a horizontal cross section in a lens are formed in a convex shape. Accordingly, even when a prism is not formed, alight transmitting through the lens is largely refracted and an interior section is hard to be visible. As a result, it is not necessary to finish a surface of a reflection surface of a reflector so as to have an optical performance equal to or more than an optical performance required for reflection with taking an appearance into consideration, and a working operation can be easily executed in comparison with the conventional one.

Since sub-reflectors are built on left and right of a longitudinal main reflector, respectively, a headlamp can be made compact longitudinally if viewed from the front. By making the headlamp compact longitudinally if viewed from the front, the sub-reflectors are provided longitudinally, i.e., provided to be elongated vertically. Therefore, luminous intensity distribution patterns diffused downward can be obtained.

Headlamp

A first reflection surface of a reflector is set up for a first brightness-intensity distribution pattern to be projected through a flat lens to conform to a target brightness-intensity distribution pattern. A displacement between the target brightness-intensity distribution pattern and a second brightness-intensity distribution pattern is calculated, the second brightness-intensity distribution pattern being reflected by the first reflection surface and to be projected through a curved lens. A second reflection surface of the reflector is set up for the displacement to become substantially a zero.

Method and apparatus using B-spline reflective surface and curved lens to render it difficult to see reflector through lens

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 of 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. The shapes of said cavities are previously designed so that portions of the molten glass corresponding to the Fresnel-type prism elements flow substantially only within small area corresponding to the corresponding Fresnel-type prism elements while the sheet glass is being pressed. This method permits to minimize surface defects such as wrinkle caused during forming, reduce the time required for forming, and to form a Fresnel lens having excellent optical properties.

Method for forming fresnel-type prism lens

In a projector-type head lamp, a reflector having a concave inner reflecting surface, a light source, a shade with a cut-off edge and a projection lens are arranged in order. The inner reflecting surface of the reflector has at least 2 foci and is so designed as to reflect the rays of light emitted from the light source in a direction crossing the optical axis. The light source is disposed near one of the foci of the reflector while the cut-off edge of the shade is arranged in the vicinity of the other focus. The projection lens has an optical axis nearly coincident with that of the reflector and is so formed that the power of refraction thereof becomes progressively greater from the optical axis toward the outer circumference, namely, its peripheral lens area has a focus located in the vicinity of the cut-off edge while its central lens area has a focus located between the cut-off edge and the light source. The colored rays having passed through the peripheral lens area near the outer circumference of the projection lens form a sharp image of the cut-off edge of the shade on a screen, while the white rays having passed through the central lens area in which the optical axis lies form a blurry image of the cut-off edge on the screen. In an illumination pattern defined on the screen, the color fringes formed in the vicinity of the cut-off line are covered by the blurry image defined by the white rays having passed through the central lens area, thereby making the color fringes sufficiently unnoticeable.

Projector-type head lamp for motor vehicles

The automotive lamp assembly according to the present invention comprises a divergent-type concave mirror formed by a central reflecting area in which the optical axis lies and peripheral reflecting areas continuously extending rightward and leftward from the central reflecting area, and a lamp bulb disposed on the optical axis of the concave mirror. Either one of the central and peripheral reflecting areas is formed as a first reflecting curved surface composed of a part of a paraboloid of revolution to reflect the incident rays of light from the lamp bulb in directions parallel to the optical axis, and the other is formed as a second reflecting curved surface to reflect horizontally the rays of light from the lamp bulb in directions divergent from the optical axis depending upon the distance from the vertical plane in which the optical axis lies and also reflect vertically the rays of light in directions parallel to each other and to the horizontal plane in which the optical axis lies. The first reflecting curved surface defines a central hot zone in the light distribution pattern, and the second reflecting curved surface defines middle and low illuminance zones extending rightward and leftward from the center of the light distribution pattern. Therefore, the rays of light from the lamp bulb can be effectively utilized and a desired light distribution pattern can be freely obtained.

Automotive lamp assembly

The automotive lamp assembly according to the present invention comprises a divergent-type concave mirror formed by a central reflecting area in which the optical axis lies and peripheral reflecting areas continuously extending rightward and leftward from the central reflecting area, and a lamp bulb disposed on the optical axis of the concave mirror. Either of the central and peripheral reflecting areas is formed as a first reflecting curved surface composed of a part of a paraboloid of revolution to reflect the incident rays of light from the lamp bulb in directions parallel to the optical axis, and the other is formed as a second reflecting curved surface to reflect horizontally the rays of light from the lamp bulb in directions divergent from the optical axis depending upon the distance from the vertical plane in which the optical axis lies and also reflect vertically the rays of light in directions parallel to each other and to the horizontal plane in which the optical axis lies. The first reflecting curved surface defines a central hot zone in the light distribution pattern, and the second reflecting curved surface defines middle and low illuminance zones extending rightward and leftward from the center of the light distribution pattern. Therefore, the rays of light from the lamp bulb can be effectively utilized and a desired light distribution pattern can be freely obtained.

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. This projector-type head lamp provides a horizontally elongated light distribution pattern of which the profile line is nearly horizontal on the side nearest the vehicle and which contributes to the effective illumination.

Projector-type head lamp for vehicles

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. Thereby, the color fringes caused by the chromatic aberration of the convergent lens appear within the main illuminated zone below the light-dark limit so that the existence of the color fringes is not conspicuous.

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. The shapes of said cavities are previously designed so that portions of the molten glass corresponding to the Fresnel-type prism elements flow substantially only within small area corresponding to the corresponding Fresnel-type prism elements while the sheet glass is being pressed. This method permits to minimize surface defects such as wrinkle caused during forming, reduce the time required for forming, and to form a Fresnel lens having excellent optical properties.

Fresnel-type aspheric prism lens

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.

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. The orientations of the fine surface elements belonging to the first to third reflection surface area are so determined that the incident light rays from a light source are converged to near the center of the edge of the shade; into a horizontal zone including up to a position spaced a predetermined distance along the meridional image plane of the convex lens from the center of the edge of the shade; and into a vertical zone including up to a position extended downward from the center of the edge of the shade, respectively. Thereby, the luminous intensity distribution pattern projected in front of a car provides a sufficient horizontal divergence and intensity of light beam while keeping the high luminous intensity at the center, so that the relatively near range in front of the car is provided with a sufficiently wide horizontal illumination.

Growing community of inventors

Isehara, Japan

Yutaka Nakata