JPH022241B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a headlamp lens that can be used in the field of vehicle lamps.

[Prior Art] Automotive headlamps usually include a housing,
The main components are a reflector, a front lens, and a bulb, but the front lens is the most problematic in terms of weight and productivity. In other words, in terms of weight, the front lens accounts for 50% of the total weight of the headlamp.
These factors are an impediment to reducing the weight of headlamps, and from a productivity standpoint, the yield of lens molding is low due to the complicated and highly precise lens cut and the high requirement for transparency. It was a bad idea.

When molding glass lenses used in conventional headlamps, (a) reducing the wall thickness reduces yield.

(b) If the step (thickness difference) in the lens cut is too large or too small, the yield will decrease.

(c) The lens surface is slightly warped, but the smaller the warpage and the flatter the lens, the lower the yield.

There is a tendency.

Regarding (a) above, it is related to the fluidity of the molten glass during pressing, and if the mold is made thinner, it becomes difficult for the glass to reach the details (particularly the periphery) of the mold. For this reason, countermeasures have been taken such as setting the mold temperature higher than when pressing other products and setting the press pressure higher, but there are limits, and considering the original strength of the glass, Lenses are on the market.

Regarding (c) above, situations such as the mold sticking or the product deforming occur due to the mold jamming immediately after pressing. When the lens is curved, the force with which it adheres to the mold differs between the male and female molds, and the pressed product fits into the mold on the concavely warped side, resulting in a constant product shape. However, as this warpage decreases and approaches a flat plate, the difference in adhesive force decreases and deformation becomes more likely to occur. Furthermore, the fact that the closer the product is to a flat plate, the more noticeable the distortion of the product is, is also cited as a reason for the resulting poor yield.

Of the above (b), the reason why the yield decreases when the step difference is extremely large is related to the fluidity of the glass and can be easily understood. On the other hand, the reason why the yield decreases when the step height is extremely small (the lens cut is shallow) is that the male
Related to the problem of adhesion to the female mold.

By the way, in order for the press product attached to the mold to separate, air must enter between them, but since the surface of the lens needs to be smooth and polished, there is no room for air to enter, and it instantly It takes a lot of force to try to let go. In this respect, the unevenness caused by the lens cut acts as an air inflow path when the molds are separated, and this makes the adhesion force of the male and female molds significantly different, making it easier to separate the molds. When the lens cut becomes shallow, it becomes difficult to expect this air inflow effect, and the yield decreases.

Next, conventional lenses are mainly thick with shallow cuts, but compared to thin lenses with shallow lens cuts, they have the drawback of lower light utilization efficiency, especially lower transmittance.

[Problems to be Solved by the Invention] The present invention has been made to solve all of the above-mentioned conventional problems, and aims to provide a headlamp lens that is lightweight, has good productivity, and has excellent transmission performance. It is something to do.

[Means for Solving the Problems] In solving the problems, the gist of the present invention is to form a lens surface substantially flat and provide a plurality of linear protrusions on this lens surface. It is something.

[Example] Hereinafter, the present invention will be specifically explained with reference to the illustrated example. Reference numeral 1 denotes a thin press-molded glass lens body, the lens surface 1a of which is formed substantially flat; has multiple linear protrusions 1
b, 1c are formed. These linear protrusions are arranged in consideration of the light distribution characteristics of the headlamp, with the vertical linear protrusions 1b serving to spread the luminous flux in the horizontal direction, and the horizontal linear protrusions 1c serving to spread the luminous flux in the vertical direction. It has the effect of expanding the Ideally, the light distribution of the headlamp should be narrow vertically and widen by about ±30° horizontally, so it is preferable to have fewer horizontal linear protrusions 1c that spread the luminous flux in the vertical direction. In particular, when using a halogen light bulb ( _H4 light bulb), avoid providing a horizontal linear protrusion slightly above the position indicated by the dashed line l in Figure 1, as this will cause upward scattered light (glare light). Should. In other parts, there are many horizontal linear protrusions 1c (10
(more than one book), there is a risk that the headlamp will become useless due to its light distribution characteristics. As a result of actual testing, it was confirmed that when a normal headlamp has 6 to 7 horizontal linear protrusions, the glare tends to worsen, and when there are 5 or less, the glare is practically within acceptable limits. .

Furthermore, if the width of the linear protrusions is too wide, the loss of light will increase, which is undesirable.As shown in FIG. 30mm), and furthermore, the height H of the linear protrusion must be kept within 3% for practical purposes.
It is about 0.3 to 1 mm.

These linear protrusions are formed by the recesses 2a of the lens molding die 2, as shown in FIG. During separation, it acts as an air inflow passage and helps facilitate separation of the mold without applying excessive force to the pressed product (lens).

During press molding of lenses, in order to press a mass of molten glass into the product shape, it is necessary to completely expel the air between the lenses so that the glass can spread along the shape of the mold. The larger the area, the more difficult it becomes to expel air, and the effect of expelling air will be significantly different depending on whether the mold 2 has the recess 2a or not.
Further, a small amount of air left behind at the final stage of pressing is forced into the recess 2a of the mold 2 and can function as a cushion material during pressing. Furthermore, the concave portion 2a of the mold 2 can absorb variations in the volume of the molten glass, and as a result, even if the absolute value of the press pressure is lowered, the lens surface can be formed neatly. Therefore, the productivity of lenses can be improved, and the yield can be dramatically improved.

The lens according to the present invention is configured as described above,
In particular, a known composite reflecting mirror 3 as shown in Fig. 4 (a reflecting mirror formed by connecting parabolic cylinder surfaces 3a, the reflected light beam does not spread vertically but spreads horizontally).
When used in combination with this, great effects can be achieved.

[Effects of the Invention] As explained above, according to the present invention, since the lens body is formed thin, the weight of the lens can be reduced, and the production of lens molding can be achieved through the concave portion of the mold. You can increase your sexuality. Also,
The lens surface is formed thin and flat, and even if the surface of the mold is sufficiently polished, there is little deformation and the surface becomes glossy, so the transmittance of the molded lens can be significantly improved. When polishing the surface of the mold, the shavings easily enter the recesses and are removed from the polished surface, which is convenient because the polishing operation using the grindstone 4 or the like can be easily performed.

In the case of the present invention, since the lens structure does not require press-forming by applying excessive force, the strength of the lens can be improved, and in addition, the linear projections formed on the lens surface can be improved. Since it acts as a rib that reinforces the lens surface, it is possible to maintain sufficient strength even if the basic thickness of the lens body is made thinner than that of conventional lenses. Therefore, a headlamp lens with high light transmittance and high strength can be obtained.

When the lens cut becomes shallow, the inside of the lamp tends to be clearly visible and the appearance deteriorates, but in the case of the present invention, linear protrusions are provided vertically and horizontally on the lens surface, so the inside of the lamp can be seen. It is possible to prevent defects, maintain good appearance, and improve design.

Note that the present invention can be applied not only to lenses made of glass but also to lenses made of plastic. Furthermore, if emphasis is placed on the design, it is also possible to color the linear protrusions to make the lines look tight.

[Brief explanation of drawings]

Fig. 1 is a front view showing an example of the lens according to the present invention, Fig. 2 is a sectional view taken along the line AA, Fig. 3 is a sectional view of the main part of the mold, and Fig. 4 is a composite reflection This figure shows the mirror, with A being a partially cutaway plan view and B being a front view. 1... Lens body, 1a... Lens surface, 1b...
...Vertical linear projection, 1c... Horizontal linear projection, 2... Mold, 2a... Recess.

Claims (1)

[Scope of Claims] 1. A lens for a headlamp, characterized in that the lens surface is formed substantially flat and a plurality of linear protrusions are provided on the lens surface. 2. The headlamp lens according to claim 1, wherein the width of the linear protrusions is set to 3% or less of the average pitch of the linear protrusions arranged side by side in the horizontal direction. 3. The number of linear protrusions provided in the horizontal direction is 5.
A headlamp lens according to claim 1, characterized in that the headlamp lens has the following properties.