Motorbike headlight

Abstract: A light distribution screen 20 is constructed of a main light distribution region 21 including a main optical axis, a low light intensity region 24 darker than an upper part of the main light distribution region 21, and high light intensity regions 22 and 23 brighter than an upper region of the low intensity region 24. A corner can be brightly illuminated when the motorcycle is cornering, which means that the visibility of the corner can be improved and oncoming traffic is not dazzled when the motorcycle is travelling straight on.

Description: The present invention relates to a motorcycle headlight according to the preamble of claim 1. Fig. 16 (a) and Fig. 16 (b) are overhead views showing the light distribution for a dipped beam of a conventional motorcycle headlight. Fig, 16 (a) shows the case when travelling in a straight line while Fig. 16 (b) shows the case when cornering. In Fig. 16 (a), the headlight 100 shines light having a left and right spread on the road surface in the relative foreground in front of the motorcycle so as not to dazzle vehicles coming in the opposite direction. In Fig. 16 (b), during cornering, the motor bike 101 leans into the corner, and a portion 103 of the light distribution inside the corner moves to the side of the motor bike 101. Fig. 17 (a) and Fig. 17 (b) are overhead views showing light distribution of a main beam of a conventional motorcycle headlight. Fig.. 17 (a) is when the motorcycle is travelling straight on, while Fig. 17 (b) is when the motorcycle is cornering. In Fig. 17 (a), the headlight 100 illuminates the road surface along distance in front of the motorcycle 101. In Fig. 17 (b), during cornering, the motorcycle 101 leans into the corner and a portion 103 of the light distribution 102 inside the corner moves to the side of the motorcycle 101. Fig. 18 (a) and Fig. 18 (b) show a light distribution screen for a conventional motorcycle headlight at the time of cornering. Fig. 18 (a) corresponds to the dipped beam in Fig. 16 (b) while Fig. 18 (b) corresponds to the travelling straight beam in Fig. 17 (b), and the main light distribution region 104 of Fig. 18 (a) and the main light distribution region 105 of Fig. 18 (b) both slope downward to the left. As shown in Fig. 16 (b) and Fig. 17 (b), the amount of light reaching the shoulder 107 of a corner seen by the rider 106 of the motorcycle 101 during cornering, and the amount of light reaching the road surface 108 ahead of the shoulder 107 is reduced, and these regions become dark. That is, at the time of cornering, because there is no light distributed in the ranges A1 and A2 in Fig. 18 (a) and Fig. 18 (b), which include the shoulder 107 and the road surface 108, there is a need to improve the forward visibility of the corner by distributing light in these ranges A1 and A2. Also, in Japanese Utility Model Publication Sho 59-13685, entitled "Headlight for Vehicle", and Japanese Patent publication Sho 63-312280 entitled "Headlight for Motorcycle", techniques for adjusting light distribution using lenses and reflectors are disclosed, but with respect to lighting up a corner during cornering, insufficient consideration is given to where and at what brightness light is irradiated. The closest prior art according to US-A-5 171 082 discloses a vehicular headlamp having a reflector with the capability for controlling the luminous intensity distribution so as to attain a balance between the spread of light in luminous intensity distribution in the horizontal direction and the brightness required in the central part of the distribution. The reflecting surface of the reflector is divided into a plurality of regions in accordance with the necessary action of controlling the luminous intensity distribution. Bosch, Kraftfahrtechnisches Taschenbuch, 21st edition, 1991, pages 132 and 676 to 679, discloses a standard light distribution screen having a horizontal line and a vertical line and an asymmetric main light intensity region formed such that part of the main light intensity region extends above the horizontal line on one side of the vertical line. Therefore, an object of the present invention is provide a headlight for a motorcycle which enabled an improvement in the visibility of corner during cornering. In order to achieve the above described object, the present invention proposes a headlight for a motorcycle according to claim 1. When the motorcycle is cornering, it is possible to brightly light up the corner, and it is possible to improve the visibility of the corner, as well to prevent the dazzling of oncoming vehicles when travelling straight ahead. Because the light distribution screen is constructed of a main light distribution region including a main optical axis, a low light intensity region darker than an upper part of the main light distribution region, and a high light intensity region brighter than an upper region of the low intensity region, a corner can be brightly illuminated when the motorcycle is cornering, which means that the visibility of the corner can be improved and oncoming traffic is not dazzled when the motorcycle is travelling straight on. Preferably, the high light intensity region is provided with a region where the light distribution is at least 200 candela at an upper side from 4U. It is possible to ensure sufficient brightness when cornering. Because the high light intensity regioms provided with a region where the light distribution is at least 200 candela at an upper side from 4U, it is possible to ensure sufficient brightness when cornering. Preferably, the high light intensity region is outside 10R and outside 10L. It is possible to prevent light from the high light intensity region entering the rearview mirror of a car or motorcycle stopped in front, when waiting at a traffic light, etc. Because the high light intensity region is outside 10R and outside 10L, it is possible to prevent light from the high light intensity region entering the rearview mirror of a car or motorcycle stopped in front, when waiting at a traffic light, etc. Preferably, the high light intensity region does not exceed 1000 candela. Light from the high intensity light region substantially does not dazzle oncoming vehicles. Since the high light intensity region does not exceed 1000 candela, it is difficult for light from the high intensity light region to dazzle oncoming vehicles. Preferably, the headlight carries out light distribution using a plurality of prisms formed in a lens, and said first and second high light intensity regions are formed using at least some of said prisms. The high light intensity region can be formed easily. Preferably, the headlight is a projector type headlight, and said first and second high light intensity regions are formed by providing non shielded portions in a light shielding section contained inside the headlight, in order to form a dipped beam pattern. It is possible to form the high light intensity region easily, and it is possible to effectively utilize shielded light. Preferably, the headlight is either a multi-reflector type headlight having a plurality of reflecting surfaces forming a reflector, or a single curved surface reflector type headlight having a single curved surface as a reflecting surface, and said first and second high light intensity regions are formed at part of said reflector. The high light intensity region can be formed easily. Embodiments of the present invention will now be described based on the attached drawings. The drawings are viewed in the direction of the symbols. Fig. 1 is a cross sectional drawing showing a first embodiment of a motorcycle headlight according to the present invention. Fig. 2 is a light distribution screen for a dipped beam of the first embodiment of the motorcycle headlight according to the present invention when travelling straight on. Fig. 3 is a drawing showing light intensity distribution for line 3-3 in Fig. 2. Fig. 4 is a light distribution screen for a main beam of a first embodiment of the motorcycle headlight according to the present invention when travelling straight on. Fig. 5 is a light distribution screen for a dipped beam of the first embodiment of the motorcycle headlight according to the present invention when cornering. Fig. 6 is a light distribution screen for a main beam of the first embodiment of the motorcycle headlight according to the present invention when cornering. Fig. 7 is an overhead view of a motorcycle housing the first embodiment of the headlight according to the present invention, during cornering. Fig. 8 is an overhead view of a motorcycle housing the first embodiment of the headlight according to the present invention, during cornering. Fig. 9 is an overhead view explaining light distribution of the headlight of the present invention. Fig. 10 is a graph for obtaining light distribution of the headlight of the present invention. Fig. 11 is a front elevation of a motorcycle for obtaining the light distribution of the headlight of the present invention. Fig. 12 is a schematic diagram for obtaining the light distribution of the headlight of the present invention. Fig. 13 is a graph for obtaining light distribution of the headlight of the present invention. Fig. 14 is a perspective diagram showing a second embodiment of a headlight of the present invention. Fig. 15 is a perspective diagram showing a third embodiment of a headlight of the present invention. Fig. 16 is an overhead view showing light distribution for a dipped beam of a conventional motorcycle headlight. Fig. 17 is an overhead view showing light distribution for a main beam of a conventional motorcycle headlight. Fig. 18 is a drawing showing a light distribution screen for a conventional motorcycle headlight when cornering. Fig. 1 is a cross sectional diagram of a first embodiment of a motorcycle headlight according to the present invention. The headlight 10 is a projector type comprised of a lightbulb 11, a reflector 12, a lens 13, and a light shielding section 14 provided between the lightbulb 11 and the lens 13. 15 is a cylindrical member. The light shielding section 14 shields light reflected by a reflecting surface 12a at the under half of the reflector 12, and forms a dipped beam pattern in which light does not reach to an upper region in a horizontal direction, and has windows 14a, which are non shielded regions, at an upper portion (two windows 14a, 14a, are aligned in the direction orthogonal to the sheet of the drawing, but one side has been omitted). Light output from the lightbulb 11 and reflected by the upper reflecting surface 12a of the reflector 12 passes through the lens 13, and travels downward from a horizontal direction as shown by 1 ○ in the drawing. Also, some of the light reflected by the lower reflecting surface 12a of the reflector 12 passes through the windows 14a in the light shielding section 14 and the lens 13 and travels as shown at 2 ○ in the drawing. This light forms the high light intensity region, as will be described later. Fig. 2 shows a light distribution screen for a dipped beam in the first embodiment of the present invention when travelling straight on, in which the light distribution screen 20 of the headlight 10 (refer to Fig. 1) comprises a main light distribution region 21 below an H line and including a main optical axis, high intensity light regions 22 and 23, located above the H line and on both sides of a V line, and a low light intensity region 24 formed between the main light distribution region 21 and the high intensity light regions 22 and 23. Fig. 3 is a drawing showing light intensity distribution along a line 3 - 3 in Fig. 2, and shows that the light intensity of the high light intensity region 23 (and 22) of the present invention satisfies the minimum required values of 0.5U 1.5L for dazzle prevention for a dipped beam in American SAE standard J854 (DEC 83) and the control value of 1000 candela MAX for outside those regions (passing on the right side), for example, not exceeding 1000 candela. Also, the high light intensity region 23 (and 22) is provided with a portion of at least 200 candela at an upper side of 4U. Fig. 4 shows a light distribution screen for a main beam in the first embodiment of the present invention when travelling straight on, in which the light distribution screen 25 of the headlight 10 (refer to Fig. 1) comprises an elliptical main light distribution region 26 having a long axis on the H line, and a short axis on the V line, and high light intensity regions 27 and 28 located above the left and right ends of the main light distribution region 26. Next, operation of the above described headlight 10 will be described. Fig. 5 (a) and Fig. 5 (b) show light distribution screens for a dipped beam of the first embodiment of the headlight of the present invention, when cornering. Fig. 5 (a) shows the state when the headlight is leaning to the left, and Fig. 5 (b) shows the state when the headlight is leaning to the right. In Fig. 5 (a), when the motorcycle is in the middle of cornering around a left corner, the frame of the motorcycle is leant to the left. As a result, the headlight also leans. At that time, the high light intensity region 22 of the light distribution screen 20A moves lower than the H line. This position of the high light intensity region 22 corresponds to the shoulder of the corner and the road surface in front of the shoulder, as will be described later. In Fig. 5 (b), when the motorcycle is in the middle of cornering around a right corner, the frame of the motorcycle is leant to the right, opposite to Fig. 5 (a), the headlight 10 leans to the right, and the high light intensity region 23 of the light distribution screen 20B moves lower than the H line. The position of this high light intensity region 23 also corresponds to the shoulder of the corner and the road surface in front of the shoulder. Fig. 6 (a) and Fig. 6 (b) show light distribution screens for a main beam of the first embodiment of the headlight of the present invention, when cornering. Fig. 6 (a) shows the state when the headlight is leaning to the left, and Fig. 6 (b) shows the state when the headlight is leaning to the right. In Fig. 6 (a), when the motorcycle is in the middle of cornering around a left corner, the frame of the motorcycle is leant to the left As a result, the headlight 10 (refer to Fig. 1) also leans. At that time, the high light intensity region 27 of the light distribution screen 25A moves lower than the H line. This position of the high light intensity region 27 corresponds to the shoulder of the corner and the road surface in front of the shoulder, as will be described later. In Fig. 6 (b), when the motorcycle is in the middle of cornering around a right corner, the frame of the motorcycle is leant to the right, opposite to Fig. 6 (a), the headlight 10 leans to the right, and the high light intensity region 28 moves lower than the H line. The position of this high light intensity region 28 also corresponds to the shoulder of the corner and the road surface in front of the shoulder. Fig. 7 is an overhead view of a motorcycle that has been installed with a first embodiment of a headlight of the present invention, during cornering, and shows light distribution when the headlight is producing a dipped beam, corresponding to the light distribution screen 20A of Fig. 5 (a). The motor bike is leant to the left, and the region 22a is lit up. This region 22a corresponding to the high light intensity region 22 is the point on the shoulder 32 of the corner or the road surface 33 in front of the corner that the rider 2 is looking directly at when cornering. Because of this, it is possible to corner comfortably by brightly lighting up the region 22a. Fig. 8 is an overhead view of a motorcycle that has been installed with a first embodiment of a headlight of the present invention, during cornering, and shows light distribution when the headlight is producing a main beam, corresponding to the light distribution screen 25A of Fig. 6(a). The motor bike is leant to the left, and the region 27a is lit up. This region 27a corresponding to the high light intensity region 27 is the point on the shoulder 32 of the corner or the road surface 33 in front of the corner that the rider 2 is looking directly at when cornering. Because of this, it is possible to corner comfortably by brightly lighting up the region 27a. Next, the method of positioning and determining the light distribution of the high light intensity region described above will now be described in order. Fig. 9 is an overhead view explaining the light distribution of the headlight of the present invention, and considers the case where a motorcycle 1 is travelling around a corner at a speed v. At this time, it is assumed that the headlight 10 describes a locus of radius R1. Also, if the radius of the road shoulder is R2, and a straight line through the headlight 10 comes into contact with a point of the road shoulder 32, a distance B in the top to bottom direction of the drawing, and a distance C in the left to right direction of the drawing, from the headlight 10 to the road shoulder 32 can be obtained from the radii R1 and R2, and further; an angle  can be obtained formed by a straight line D extending in a forward horizontal direction from the headlight 10 on a central plane of the vehicle, and a straight line F linking between the headlight 10 and a point 32a. Further, the length L1 of the straight line F can be obtained. Fig. 10 is a graph for obtaining the light distribution of a headlight of the present invention, and shows the relationship between the speed of the motorcycle when cornering and a banking angle. The horizontal axis represents speed, while the vertical axis represents bank angle, and shows R1= 20m and 50m as the previously described radius R1 of the locus of the headlight. First of all, in this graph, the bank angle a is obtained from the speed v and the radius R1. Figs. 11 (a) and 11 (b) are front elevations of a motorcycle for obtaining the light distribution of the headlight of the present invention. Fig; 11 (a) shows the case when travelling straight on, while Fig. 11 (b) shows the case when cornering. In Fig. 11 (a) the height from the ground surface E to the headlight 10 is h1. In Fig. 11 (b), the height h2 from the ground surface E to the headlight at the time of cornering is obtained from the bank angle a at the time of cornering and the height h1 in Fig. 11 (a). Fig. 12 is a schematic view for obtaining the light distribution of the headlight of the present invention, and for convenience, the left side of the drawing is the ground surface. Here, it is possible to obtain an actual distance L2 from the headlight 10 to the road shoulder 32, and an angle β formed by a line J connecting between the headlight 10 and the road shoulder 32, and a horizontal line G (shown in the vertical direction in the drawing) passing through the headlight 10 from the length L1 obtained in Fig. 9, and the height h2 obtained in Fig. 11. Fig. 13 is a graph for obtaining the light distribution of the headlight of the present invention, and shows the relationship between required road surface illumination and visible distance. The horizontal axis represents the visible distance L2 at the previously described actual distance, while the vertical axis represents road surface illumination K. Using this graph, it is possible to obtain the required road surface illumination K from the visible distance L2 obtained in Fig. 12. The location and light distribution of the high light intensity region can be obtained from the angle  in the horizontal direction the angle β in the vertical direction and the road surface illumination K. Fig. 14 is a perspective drawing showing a second embodiment of the headlight of the present invention. The headlight 40 is comprised of a lightbulb 41, a reflector 42, a housing 43 integrally formed with the reflector 42, and a lens 44. Light distribution is carried out by a plurality of prisms formed in the lens 44, and a high light intensity region is also formed by at least some of the prisms. The formation of the prisms for the high light intensity region can be carried out according to conventional technology, and the high light intensity region can be easily formed. Fig. 15 is a perspective drawing showing a third embodiment of the headlight of the present invention. The headlight 50 is comprised of a lightbulb 51, a reflector 52, a housing 53 integrally formed with the reflector 52, and a lens 54. There is either a multi reflector type reflector having a plurality of reflecting surfaces formed in the reflector 52, or a single curved surface type reflector in which the reflecting surface of the reflector 52 is formed as a single curved surface, and at least part of the reflector 52 also forms a high light intensity region. The formation of the reflecting surface of the reflector 52 for the high light intensity region can be formed according to conventional technology, and the high light intensity region can be easily formed. The shape and location of the high light intensity regions of the present invention are not limited to those described here, and may differ to reflect a prescribed range of speed v, radius R1, road surface coefficient of friction, etc. Also, as long as the headlights 10, 40 and 50 have the same structure, the detailed construction thereof can be disregarded. Summarized, a light distribution screen is constructed of a main light distribution region including a main optical axis, a low light intensity region darker than an upper part of the main light distribution region ., and high light intensity regions and brighter than an upper region of the low intensity region A corner can be brightly illuminated when the motorcycle is cornering, which means that the visibility of the corner can be improved and oncoming traffic is not dazzled when the motorcycle is travelling straight on.

Claims: A headlight for a motorcycle having a main optical axis and a light distribution on a light distribution screen (20; 25), the light distribution screen (20; 25) having a horizontal line (H) and a vertical line (V), the main optical axis of the headlight being aligned with the vertical line (V) and on or below the horizontal line (H) when a motorcycle frame is in its upright position, wherein said light distribution comprises a main light distribution region (21; 26) including the main optical axis and a low light intensity region (24) darker than an upper part of said main light distribution region (21; 26), characterized in that said light distribution further comprises a first and a second high light intensity region (22; 27 and 23; 28) brighter than an upper region of said low light intensity region (24) and located sidewards of the vertical line (V) and above the horizontal line (H) when said motorcycle frame is in the upright position; wherein said low light intensity region (24) is formed between the main light distribution region (21; 26) and said first and second high light intensity regions (22; 27 and 23; 28); and wherein one of said first and second high light intensity regions is located lower than the horizontal line (H), when the motorcycle frame is leant to that side of the vertical line (V) comprising said one high light intensity region while cornering. The headlight according to claim 1, wherein said high light intensity region (22; 23) is provided with a portion having a light intensity of at least 200 candela at an upper side from 4U. The headlight according to claim 1 or 2, wherein said high light intensity region (22; 23) is outside 10R and outside 10L. The headlight according to one of claims 1 to 3, wherein light distribution of said high light intensity region (22; 23) does not exceed 1000 candela. The headlight according to one of claims 1 to 4, wherein said headlight (40) carries out light distribution using a plurality of prisms formed in a lens (44), and said first and second high light intensity regions are formed using at least some of said prisms. The headlight according to one of claims 1 to 4, wherein said headlight (10) is a projector type headlight, and said first and second high light intensity regions are formed by providing non shielded portions (14a) in a light shielding section (14) contained inside the headlight (10), in order to form a dipped beam pattern. The headlight according to one of claims 1 to 4, wherein said headlight (50) is either a multi-reflector type headlight having a plurality of reflecting surfaces forming a reflector (52), or a single curved surface reflector type headlight having a single curved surface as a reflecting surface, and said first and second high light intensity regions are formed at part of said reflector (52).

Inventors: HIROSE YOSIHISA, NAGATUYU TOSHIYA, SUZUKI TETSUYA, TABATA HAJIME, HIROSE, YOSIHISA, NAGATUYU, TOSHIYA, SUZUKI, TETSUYA, TABATA, HAJIME
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1997
Main classification: B60Q1
IPC codes: B62J6, F21S8, B60Q1