1. Field of the Invention
The present invention relates to optical units and, in particular, relates to an optical unit used in a vehicle lamp.
2. Description of the Related Art
A vehicle lamp, provided with an optical unit including a rotary reflector that rotates unidirectionally about the axis of rotation while reflecting light emitted by a light source, is known (see JP2010-092124). The rotary reflector is provided with a plurality of blades arranged in the circumferential direction about the axis of rotation, and each blade is provided with a reflective surface by which the light is reflected to form a desired light-distribution pattern. Light reflected by the blades is projected toward the front of the vehicle lamp through a projection lens.
When a vehicle provided with a vehicle lamp such as the one described above travels during daytime, the sunlight incident on the lamp may be condensed by the projection lens onto the reflective surfaces of the blades of the rotary reflector, and the blades may melt and be damaged.
The present invention has been made in view of such an issue and is directed to providing a technique for preventing a blade from melting and being damaged by light incident on a projection lens and condensed thereby in an optical unit provided with a rotary reflector.
An optical unit according to an aspect of the present invention includes a light source; a rotary reflector that rotates about an axis of rotation and includes a reflective surface that reflects light emitted by the light source; and a projection lens having an incident surface on which reflected light from the rotary reflector is incident. A shade is provided between the projection lens and the rotary reflector, and the shade blocks at least a portion of light that has been incident on an emission surface of the projection lens at an angle within a predetermined range, that has been condensed by the projection lens, and that travels toward the reflective surface of the rotary reflector.
Embodiments will now be described by way of examples only, with reference to the accompanying drawings which are meant to be exemplary, not limiting and wherein like elements are numbered alike in several Figures in which:
An optical unit according to an aspect of the present invention includes a light source; a rotary reflector that rotates about an axis of rotation and includes a reflective surface that reflects light emitted by the light source; and a projection lens having an incident surface on which reflected light from the rotary reflector is incident. A shade is provided between the projection lens and the rotary reflector, and the shade blocks at least a portion of light that has been incident on an emission surface of the projection lens at an angle within a predetermined range, that has been condensed by the projection lens, and that travels toward the reflective surfaces of the rotary reflector.
According to this aspect, light to be condensed by the projection lens onto the reflective surfaces of the blades is blocked by the shade, and thus the blades can be prevented from melting and being damaged.
The shade may be provided at a position at which the shade does not block reflected light from the rotary reflector. This configuration makes it possible to eliminate an influence of the shade on a light-distribution pattern formed by the optical unit.
The shade may be made of metal. This configuration makes it possible to prevent the shade itself from melting and being damaged by the condensed light.
The invention will now be described by reference to the preferred embodiments. This does not intend to limit the scope of the present invention but to exemplify the invention. The size of the component in each figure may be changed in order to aid understanding. Some of the components in each figure may be omitted if they are not important for explanation.
(First Embodiment)
As illustrated in
The lamp unit on the outer side, or in other words, the lamp unit 20 illustrated in the upper side of
The low-beam lamp unit 18 includes a reflector 22, a light source bulb (incandescent bulb) 24 supported by the reflector 22, and a shade (not illustrated). The reflector 22 is supported by a known mechanism (not illustrated), such as a mechanism that uses an aiming screw and a nut, so as to be freely tilted relative to the lamp body 12.
As illustrated in
The rotary reflector 26 unidirectionally rotates about an axis of rotation R with a driving source 32, such as a motor. The rotary reflector 26 includes a reflective surface configured to reflect light emitted by the LED 28 to form a desired light-distribution pattern as the rotary reflector 26 rotates. In the present embodiment, the rotary reflector 26 constitutes an optical unit.
The rotary reflector 26 is provided with three blades 26a of an identical shape that function as reflective surfaces, and the blades 26a are provided on the circumference of a cylindrical rotation unit 26b. The axis of rotation R of the rotary reflector 26 is at an angle relative to an optical axis Ax and extends within a plane that contains the optical axis Ax and the LED 28. In other words, the axis of rotation R extends substantially parallel to the scanning plane of light (illumination beam) from the LED 28, which scans in the horizontal direction as the rotary reflector 26 rotates. Thus, the thickness of the optical unit can be reduced. The scanning plane can be seen, for example, as a fan-shaped plane formed by continuously connecting trajectories of the light from the LED 28 serving as scanning light. In the lamp unit 20 according to the present embodiment, the LED 28 provided therein is relatively small and is disposed at a position that is between the rotary reflector 26 and the convex lens 30 and that is offset from the optical axis Ax. Therefore, the size of the vehicle headlamp 10 in the depthwise direction (front and back direction of the vehicle) can be reduced as compared to a lamp unit of a conventional projector system in which a light source, a reflector, and a lens are disposed linearly along an optical axis.
Each blade 26a of the rotary reflector 26 is shaped such that a secondary light source of the LED 28 produced by reflection is formed near the focal point of the convex lens 30. In addition, each blade 26a has a twisted shape such that the angle formed by the optical axis Ax and the reflective surface changes along the circumferential direction with the axis of rotation being the center. This configuration enables the scan with the light from the LED 28 as illustrated in
Subsequently, the rotary reflector 26 rotates as illustrated in
In this manner, the rotary reflector 26 according to the present embodiment can scan the front of the vehicle in the horizontal direction with the light from the LED 28 by appropriately controlling the shape or the rotation speed of the blades 26a.
As illustrated in
The vehicle headlamp 10 that includes the optical unit according to the present embodiment can form a high-beam light-distribution pattern of which a desired region is blocked as illustrated in
As described thus far, the vehicle headlamp according to the present embodiment can form a light-distribution pattern by scanning with the light from the LED and form a blocked portion as desired at a portion of a light-distribution pattern by controlling the change in the light-emitting luminous intensity. Therefore, light in a desired region can be blocked with high accuracy with a small number of LEDs as compared to a case in which a blocked portion is formed by turning off some of a plurality of LEDs. In addition, the vehicle headlamp 10 can form a plurality of blocked portions, and thus even when a plurality of vehicles are present in front, light in regions corresponding to the respective vehicles can be blocked.
The vehicle headlamp 10 can control blocking of light without moving a basic light-distribution pattern, and thus a sense of discomfort from the driver can be reduced at the time of light-blocking control. In addition, a light-distribution pattern can be swiveled without moving the lamp unit 20, and thus the mechanism of the lamp unit 20 can be simplified. Therefore, it is sufficient that the vehicle headlamp 10 include, as a driving unit for variable light-distribution control, a motor necessary for rotating the rotary reflector 26, which can lead to a simple, low-cost, small-sized configuration.
(Second Embodiment)
The vehicle lamp 100 includes a lamp body 102 having a front opening, and the front opening is covered by a transparent front cover (not illustrated) to thus form a lamp room. In the lamp body 102, two lamp units 118 and 120 are disposed side by side in the widthwise direction of the vehicle.
The lamp unit 118 disposed on the outer side in the widthwise direction of the vehicle (left side in
The optical unit 120 disposed on the inner side in the widthwise direction of the vehicle (right side in
In addition to the lamp units 118 and 120, the vehicle lamp 100 may also be provided with a lamp unit of a different type.
As illustrated in
The shape of the projection lens 130 may be selected as appropriate in accordance with such light-distribution characteristics as required light-distribution pattern and illuminance distribution, and an aspherical lens or a free-form surface lens is used. In the present embodiment, a part of the projection lens 130 is cut out, which allows the rotary reflector to be seen from the front of the vehicle (see
The rotary reflector 140 rotates unidirectionally about an axis of rotation with a driving source 132, such as a motor. The rotary reflector 140 includes a plurality of blades 142 (two in the present embodiment) having a reflective surface that reflects light emitted by the LED 112 to form a desired light-distribution pattern as the rotary reflector 140 rotates by a predetermined angle, and the blades 142 are provided in the circumferential direction of a cylindrical rotation unit 144. Similarly to the blades 26a of the rotary reflector 26 according to the first embodiment, each blade 142 is shaped such that a secondary light source produced by reflection is formed near the focal point of the projection lens 130. In addition, the blade 142 has a twisted shape such that the angle formed by the optical axis and the reflective surface changes along the circumferential direction with the axis of rotation being the center. The blade 142 is typically fabricated through plastic molding.
As described with reference to
A cooling fan 150 is provided on a side opposite to the reflective surface of the blades 142 of the rotary reflector 140. The cooling fan 150 is attached to the rotation unit 144 of the rotary reflector and is driven along with the rotary reflector 140 by the aforementioned motor. The cooling fan 150 is provided on a side opposite to the reflective surface of the blades, and thus the cooling fan 150 has no influence on a light-distribution pattern formed by the rotary reflector.
The cooling fan 150 is a so-called “blower fan” in which a multi-blade unit 156 is rotatably housed in a cylindrical housing 158. The multi-blade unit 156 shares the axis of rotation with the rotary reflector 140. The cooling fan 150 is configured to take in the air through an inlet 152 formed in the base of the housing 158 and to discharge the air compressed by the rotation of the multi-blade unit 156 through an outlet 154 formed in the side face of the housing 158. As a blower fan is used as the cooling fan, the airflow can be produced in a direction orthogonal to the axis of rotation of the rotary reflector. The airflow produced by the cooling fan 150 does not directly hit the rotary reflector 140, and thus the airflow has no influence on the number of rotations or the rotation speed of the rotary reflector. In addition, as the inlet 152 is disposed on a side opposite to the rotary reflector 140, the air can be taken in without being affected by the rotary reflector.
When a vehicle provided with the vehicle lamp 100 as described above travels in daytime, depending on the condition, the blades 142 of the rotary reflector 140 may melt and be damaged by the sunlight. This will be described with reference to
The light incident on the emission surface 130a of the projection lens 130 is condensed by the projection lens at a position around the posterior focal point. At this point, the position of the focal point relative to the projection lens varies depending on the angle of the incident light due to the curvature of field of the projection lens 130.
When the angle of the incident light is 0 degrees, as illustrated in
When the angle of the incident light is 20 degrees, as illustrated in
Therefore, a blade can be prevented from melting and being damaged by blocking, of the light that is condensed by the projection lens 130 and travels toward the reflective surface of the blade of the rotary reflector, the light that travels toward the vicinity of the focal point F3 illustrated in
By blocking the light that travels toward the vicinity of the focal point F3 with the shade 160, the blades 142 can be prevented from melting and being damaged by the light incident on the projection lens 130 and condensed thereby. It is preferable that the shade 160 be made of metal. This configuration makes it possible to prevent the shade 160 itself from melting and being damaged by the light condensed by the projection lens 130.
In
In addition, as illustrated in
The angles of the incident light described with reference to
Thus far, the present invention has been described with reference to the embodiments. The present invention, however, is not limited to the foregoing embodiments and encompasses an embodiment obtained by combining or replacing configurations of the embodiments as appropriate.
In the foregoing embodiments, a case in which the lamp unit is applied to a vehicle lamp has been described, but an application is not limited to this field. For example, the lamp unit may also be applied to a lighting device for a stage or an entertainment facility in which lighting is carried out while switching various light-distribution patterns.
Number | Date | Country | Kind |
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2014-025629 | Feb 2014 | JP | national |
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2014-025629, filed on Feb. 13, 2014 and International Patent Application No. PCT/JP2015/052851, filed on Feb. 2, 2015, the entire content of each of which is incorporated herein by reference.
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Number | Date | Country | |
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20160341388 A1 | Nov 2016 | US |
Number | Date | Country | |
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Parent | PCT/JP2015/052851 | Feb 2015 | US |
Child | 15230598 | US |