JP6861536B2 - Lens structure of the lamp unit - Google Patents

Description

The present invention relates to a lens structure of a lamp unit used for a vehicle headlight or the like, and particularly relates to a lamp unit having increased productivity.

As such a lamp unit, there is a unit in which a semiconductor light source such as an LED and a projection lens arranged in front of the semiconductor light source are unitized. A convex lens is used as the projection lens.

Japanese Unexamined Patent Publication No. 2006-114347

Some projection lenses are formed by melting glass or resin material and injecting it into a mold. However, since the convex lens formed in this way has a large wall thickness at the center, the cooling of this portion is slowed down, and the difference in cooling rate from the surroundings becomes large.
If this difference in cooling rate is large, sink marks may occur in the central portion where the wall thickness is large. The sink mark is a partial deformation that occurs on the surface of the molded product due to thermal strain during solidification due to the difference in cooling rate.
If such a sink mark occurs, the quality will deteriorate, so it is necessary to mold it so that the sink mark does not occur. For that purpose, in order to reduce the difference in cooling rate between the peripheral part and the central part of the lens. , Adjustments have been made to delay the cooling of the surrounding area.
However, such delay adjustment of the cooling rate increases the overall molding time and makes it difficult to increase the productivity.
Therefore, an object of the present application is to shorten the molding time and increase the productivity while making such sink marks less likely to occur.

In order to solve the above problems, the lens structure of the lamp unit according to the present invention includes a projection lens (3) whose center is arranged on the optical axis and a light source (4) which is arranged near the focal point of the projection lens. In the provided lamp unit (1), the projection lens (3) is a convex lens, and a heat dissipation recess (5, 15, 25, 35, 45) formed along the optical axis is provided at the center thereof. It is characterized by that.
The heat dissipation recess can be a through hole (5.15.25) that penetrates the central portion of the projection lens, or a bottomed hole (35) that does not penetrate to the front side.

Of the light emitted from the light source (4), the light traveling on the optical axis passes through the heat dissipation recess, but this portion has almost no effect on the lens performance. Moreover, although this portion has the largest wall thickness, the presence of the heat radiating recess here promotes cooling during molding.
As a result, the cooling rate of the central portion can be increased, so that the overall cooling rate can be increased and the molding rate can be shortened.

Further, when the hole diameter of the heat radiating recess is changed, the light entering the heat radiating recess can be passed forward as it is by gradually increasing the diameter toward the front.
On the contrary, if the diameter is gradually reduced toward the front, the light entering the heat radiating recess is narrowed down and it becomes difficult to go out to the front.

According to the present invention, since the heat radiating recess is provided on the optical axis of the projection lens, the wall thickness becomes the largest in the vicinity of the optical axis when the molten material is injected into the mold and then cooled and solidified for molding. Cooling of the central portion is promoted by the heat dissipation recess.
Therefore, since the cooling rate for the central portion having a large wall thickness can be increased, the overall cooling rate can be increased, the molding rate can be shortened, and the productivity can be increased.

Moreover, since the heat dissipation recess is formed on the optical axis in which the light travels straight without being refracted by the convex lens, the heat dissipation recess can be formed without affecting the performance of the projection lens.
Therefore, in the projection lens, the heat dissipation recess can be provided in a place where the refraction of light is not affected and the cooling effect is highest.

Further, since the central lens is provided, the road surface at a predetermined distance ahead can be brightly illuminated by the light near the optical axis, and the road surface light distribution can be controlled.

Cross-sectional view of the lamp unit according to the first embodiment in the optical axis direction Enlarged sectional view of the projection lens in the lamp unit Cross-sectional view of the mold showing the manufacturing process The same cross-sectional view as FIG. 2 according to the second embodiment. The same cross-sectional view as FIG. 2 according to the third embodiment. The same cross-sectional view as FIG. 2 according to the fourth embodiment. Front view showing the front side of the projection lens according to the fifth embodiment. Cross-sectional view of the projection lens according to the sixth embodiment Sectional drawing which shows the modification of the projection lens which concerns on 6th Example

Hereinafter, embodiments will be described. This embodiment is a lamp unit used for a vehicle headlight or the like. However, the use of the lamp unit is not limited to headlights, and can be applied to various lighting devices.
1 and 2 relate to the first embodiment. FIG. 1 shows the lamp unit 1, in which the projection lens 3 is arranged in the opening of the housing 2, and the light source 4 is arranged at the focal point F position behind the projection lens 3.

As shown in FIG. 2, the projection lens 3 is a convex lens made of a glass or resin material, and a through hole 5 is formed in a central portion on the optical axis L in parallel with the optical axis L. The axis of the through hole 5 coincides with the optical axis L.
The through hole 5 is an example of the heat dissipation recess of the present application, is a straight hole having a circular cross section and a uniform diameter in the length direction, and penetrates from the rear surface to the front surface of the projection lens 3 on the optical axis L. ..

The actual through hole 5 is a tapered hole that is slightly inclined toward either end in the axial direction in order to provide a draft of the mold during molding. However, the inclination is such that it cannot be seen without careful attention, and it is a substantially straight hole.

The center O of the lens is a point on the optical axis L, and the central portion includes the center O, is a portion along the optical axis L, and includes a predetermined range around the optical axis L. This portion is a portion in which the light emitted from the light source 4 on the optical axis L is not refracted so much and travels straight.
Each projection lens 3 in the present embodiment uses a plano-convex lens having a convex front side and a flat rear surface side, but various lens types can be adopted. For example, a concavo-convex lens having a concave rear surface side can be adopted. , A convex lens having both front and rear surfaces convex may be used.

The hole diameter of the through hole 5 is set so that, of the light passing through the projection lens 3, the light traveling straight through the projection lens 3 around the optical axis L and substantially parallel to the optical axis L can pass through. However, since the amount of light is originally large on the optical axis L, there is no problem even if the hole diameter is slightly increased. The hole diameter can be appropriately set within a range in which unevenness of light can be tolerated when viewed from the front surface of the projection lens 3.

The light source 4 is a minute light source of a semiconductor element made of an LED, which can be regarded as a substantially point light source. The optical axis of the light source 4 is also aligned on the optical axis L, and is arranged on the focal point F on the rear side of the projection lens 3. The light source 4 is not limited to the semiconductor light source (LED), and various known light sources can be adopted. However, if a semiconductor light source is adopted, a lightweight and compact light source that is close to a point light source can be obtained.

Of the light emitted from the light source 4, the light traveling on or near the optical axis L enters the through hole 5 and travels straight, and exits in front of the projection lens 3.
On the other hand, the light that is obliquely incident on the projection lens 3 away from the optical axis L is refracted by the projection lens 3 and becomes light parallel to the optical axis L and exits forward.

At this time, the light passing through the through hole 5 is not refracted by the projection lens 3, but the light on the optical axis L has the property of traveling straight on the optical axis L of the projection lens 3 without being originally refracted. Practically, it has almost no effect on the performance of the projection lens 3 in projecting light onto the lens 3.

FIG. 3 shows the manufacturing process of the projection lens 3, and the first mold 6 and the second mold 7 are combined to form a cavity 8 corresponding to the projection lens 3 inside.
At this time, for example, the movable pin 9 is provided in the first mold 6. The movable pin 9 is provided so as to be movable back and forth on the optical axis L of the projection lens 3 as a product, and its thickness is the same as the inner diameter of the through hole 5.

The movable pin 9 is advanced in the direction of the second mold 7, and in a state where the tip is in contact with the second mold 7, a molten material made of glass or resin is injected into the cavity 8 and cooled to solidify. ..
At the time of this cooling, if necessary, the movable pin 9 can be forcibly cooled from the outside of the first mold 6 with an appropriate refrigerant, whereby the largest amount of molten material around the movable pin 9 can be efficiently and rapidly cooled. It is cooled. However, since the thermal conductivity of the movable pin 9 is good without such forced cooling, the molten material around the movable pin 9 can be cooled quickly.

After the molten material in the cavity 8 is cooled and solidified, the first mold 6 and the second mold 7 are opened, and at the same time, the movable pin 9 is retracted to obtain the projection lens 3.
In the molding of the projection lens 3, since the central portion, which requires the longest cooling time, is shortened by the movable pin 9, it is not necessary or can reduce the delay in cooling the peripheral portion, and the overall molding time is shortened. You will be able to do it.

FIG. 4 shows a second embodiment in which the hole diameter of the heat dissipation recess is changed. In this example, the heat radiating recess is the same through hole 15 as in the previous embodiment, but the through hole 15 is a tapered hole that gradually increases in diameter toward the front and expands. The degree of this taper is different from the previous embodiment, which is regarded as a straight hole, and has a large inclination angle so that the taper can be clearly recognized.

In this way, the light in the vicinity of the optical axis L that has entered the through hole 15 goes out to the front of the projection lens 3 without being blocked as it is. It becomes an effective structure in some cases.
Further, since the tapered surface of the through hole 15 provides a large draft when the movable pin 9 is pulled out to the front side of the projection lens 3, molding becomes easier.

FIG. 5 is a third embodiment, and shows a through hole 25 which is an inverted tapered hole with respect to the through hole 15 of FIG. The degree of taper is the same as that of the second embodiment.
If the through hole 25 is made into a tapered hole that expands rearward as in this example, a large draft when the movable pin 9 is pulled out to the rear of the projection lens 3 can be formed.

Further, the light entering the through hole 25 on or near the optical axis L is narrowed down so that the front side of the through hole 25 gradually becomes smaller in diameter. Therefore, the structure is effective when it is desired to limit the amount of light in the central portion of the projection lens 3.

The present application is not limited to each of the above embodiments, and various modifications and applications are possible.
For example, FIG. 6 shows a fourth embodiment in which the heat dissipation recess is a bottomed hole 35. The bottomed hole 35 is a straight hole that opens to the rear surface of the projection lens 3, but the front surface side is a dead end due to the bottom portion 36 and does not penetrate.

The bottomed hole 35 can be formed by advancing and retreating the movable pin 9 from the rear side of the projection lens 3. At this time, it may be a tapered hole as shown in FIG.
However, the bottomed hole 35 may be opened to the front surface side and the rear surface side may be the bottom portion. It is also possible to form a hole from the front and back toward the center and provide a bottom portion at the center.

In this way, the bottom portion 36 can cover the outside of the bottomed hole 35. Therefore, when the bottom portion 36 is provided on the front surface, it is possible to prevent water and dust from entering the bottomed hole 35 from the front. it can.
Further, the formation of the bottom portion 36 can be made so as not to affect the cooling of the central portion by reducing the wall thickness.

FIG. 7 is a fifth embodiment in which a plurality of heat dissipation recesses are provided, and is a front view showing the front side of the projection lens. The heat radiating recess 45 is provided with a plurality of holes along the optical axis L. Each hole is composed of any one of FIGS. 2, 4, 5, 6 or an appropriate combination thereof.
This example is effective when the range in which the heat dissipation recess 45 is formed can be relatively large in the center of the front surface of the projection lens 3.

Further, the lens used for the projection lens 3 is not limited to the plano-convex lens of each embodiment. For example, a concavo-convex lens having a concave rear surface or a convex lens having both front and rear surfaces convex may be used, and an appropriate lens type can be adopted.
Further, the light source 4 is not limited to the semiconductor light source (LED), and various known light sources can be adopted. However, if a semiconductor light source is adopted, a lightweight and compact light source that is close to a point light source can be obtained.

FIG. 8 is a sixth embodiment in which a central lens 37 having different characteristics from the projection lens 3 is provided on the bottom 36 of the bottomed hole 35 of the fourth embodiment. In this example, a convex lens-shaped center lens 37 is integrally provided on the front surface of the bottom portion 36, which is the front center portion of the projection lens 3.

The focal length F1 of the central lens 37 has a smaller focal length than the focal length F of the projection lens 3, and has characteristics different from those of the projection lens 3. Therefore, the central lens 37 controls to collect the light of the light source 4 ( FIG. 1) that has passed through the bottom hole 35.
Therefore, the headlight composed of the lamp unit 1 brightly illuminates the road surface at a predetermined distance in front of the vehicle by the light near the optical axis. Therefore, the road surface light distribution can be controlled.
If the central lens 37 is not formed and the through hole 5 is formed (FIG. 1), the light in the vicinity of the optical axis L only travels straight and directly hits the road surface, and the road surface light distribution cannot be controlled.

Further, when it is not desired to use the light in the central portion of the projection lens 3 that has passed through the low and low holes 35 for the road surface light distribution, the lens surface of the central lens 37 is diffused by applying a treatment such as grain or diamond cut. You can try to get rid of it.

The characteristics of the center lens 37 different from those of the projection lens 3 include not only the focal point but also the difference in the lens shape. An example of this is shown in enlarged portions A, B, and C in FIG.
The magnifying part A shows a central lens 37A which is a concave lens. In this way, the light in the center can be diffused.

The magnifying part B shows a central lens 37B as a Fresnel lens. In this way, the central lens can be made thinner.
The enlarged portion C shows a central lens 37 as a flat lens having a flat front surface. In this way, the design can be improved.

FIG. 9 is a cross-sectional view similar to FIG. 8 showing a modified example of the central lens 37 shown in FIG.
The central lens 37 in this example is a convex lens, but is provided at the bottom of the central hole 38 formed in the central portion of the front surface of the projection lens 3.

The central hole 38 corresponds to the bottomed hole 35 of the present application, and is formed as a tapered hole that is opened forward and widened forward.
Further, the sizes of the central lens 37 and the central hole 38 are large so that not only the light near the optical axis L but also the light spread to the surroundings can pass through, unlike the previous embodiments.

A bottom portion corresponding to the bottom portion 36 of the present application is provided on a portion including the rear surface 39 of the projection lens 3, and this bottom portion serves as the center lens 37. As in the case of FIG. 8, the focal point F2 of the central lens 37 is shorter than the focal point F of the projection lens 3. However, the light source 4 is arranged on the focal point F of the projection lens 3.

In this way, the light emitted from the light source 4 near the optical axis L is controlled by the central lens 37. That is, the light on the optical axis L travels straight through the center of the central lens 37, but the light around it travels away from the optical axis L and is not substantially parallel to the optical axis L, and to some extent with respect to the optical axis L. The tilted light is also focused by the central lens 37.

Therefore, in this example as well, the light near the optical axis of the headlight can be focused on the front center of the vehicle by the center lens 37, but the light not only near the optical axis but also around the center of the headlight is more focused. Since most of the light is focused on the front center of the vehicle, the road surface light distribution is controlled so that the road surface in this portion can be illuminated brighter.

Further, in this example, since the central lens 37 is provided on the rear surface 39 side of the projection lens 3 which is the rear portion of the central hole 38, the central lens 37 is pulled in from the front surface to the rear side of the projection lens 3 to project forward. Without it, the entire projection lens 3 can be formed thin. Further, since the central hole 38 has an opening larger than that of the central lens 37, it is possible to improve heat dissipation in the central portion during molding of the projection lens 3.

In FIG. 8, as in FIG. 9, the central lens 37 and the low hole 35 can be enlarged. Further, the diameters of the through holes and the low and low holes shown in FIGS. 1 to 7 can be increased as shown in FIG. 9, and the cooling of the central portion at the time of molding the projection lens can be made more efficient.
Here, the large diameter of the through hole, the low hole, and the central lens means that not only the light that is substantially parallel to the optical axis L but also the light that is tilted with respect to the optical axis L can pass through. To say.

1: Lamp unit, 3: Projection lens, 4: Light source, 5: Through hole (recess for heat dissipation), 15: Through hole (recess for heat dissipation), 25: Through hole (recess for heat dissipation), 35: Bottomed hole (recess for heat dissipation) Heat dissipation recess), 37: Center lens, 45: Heat dissipation recess

Claims (3)

In the lamp unit (1) including the projection lens (3) whose center is arranged on the optical axis and the light source (4) arranged near the focal point of the projection lens.
Said projection lens (3) and convex lens forward molded glass or resin material, the heat releasing recess formed by molding along said optical axis at its center the projection lens (3) (35) the provided Rutotomoni,
The heat dissipation recess is a bottomed hole provided in the center of the projection lens (3) along the optical axis direction and the bottom (36) is located in the front .
The lens structure of the lamp unit is characterized in that the bottom portion (36) is a central lens (37) having characteristics different from those of the projection lens (3). The lens structure of the lamp unit according to claim 1 , wherein the bottom portion (36) of the bottomed hole (35) is formed on the front surface side of the projection lens (3). The lens structure of a lamp unit according to claim 1 or 2, wherein the light source (4) is a semiconductor light source.

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