JPS6228522B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a reflector plate used in a lighting device such as a vehicle lamp, and in particular is made of a transparent material with a flat boundary surface on the light source side. The back surface side corresponding to the boundary surface of the transparent material is made a completely reflective surface, and the back surface side reflective surface reflects the light source light that the incident light beam incident on the boundary surface is refracted into and becomes a refracted light beam. The prism surface is formed with a predetermined inclination angle (θ) relative to the distance from the light source center point with respect to a plane perpendicular to the light source optical axis, and by performing this prism (folding) processing, the light source optical axis and This is an attempt to reduce the thickness of an illumination device that emits parallel light rays.

[Conventional technology]

In general, this type of lighting device, for example, a reflector in an automobile lamp, usually has a reflecting surface made of a parabolic mirror, and by placing a light source at the focal point on the optical axis, the reflected light rays are directed parallel to the optical axis. It has gained.

However, in such conventionally structured lights, the reflector is formed on a parabolic surface, which increases the overall depth of the light, and when installing it on a car body, etc., it requires a large installation space, especially in the area where the reflector is installed.・The degree of freedom in vehicle design is small, etc.
This has caused various problems.

[Purpose of the invention]

The object of the present invention is to solve the above-mentioned conventional drawbacks, namely, the lack of freedom in vehicle design that is lost due to the configuration of the reflector itself.

[Structure of the invention] The present invention has been made to achieve the above object,
It is made of a transparent material having a predetermined refractive index (n) and a flat boundary surface on the light source side, and the back surface side corresponding to the boundary surface of the transparent material is formed as a completely reflective surface, and the completely reflective surface is The prism surface is a prism surface that reflects the light source light, which is an incident light beam that enters the boundary surface and becomes a refracted light beam, approximately parallel to the light source optical axis, and the prism surface is set at a predetermined angle with respect to a plane perpendicular to the light source optical axis. A reflector plate formed with an inclination angle (θ) of and satisfying the following formula: In the above equation, X is the predetermined horizontal distance from the point where the incident ray reaches the boundary surface to the light source optical axis C, and Y is the horizontal axis from the point where the incident ray reaches the boundary surface to the horizontal axis passing through the light source center point O. A given vertical distance of Z
is the predetermined perpendicular distance from the point where the extension line of the boundary surface touches the light source optical axis C to the light source center point O, and α is the predetermined inclination angle that the boundary surface makes with respect to the plane perpendicular to the light source optical axis C, which is zero degrees. By using this reflector, the overall depth of the lamp becomes shallow, and the installation space becomes smaller, which increases the degree of freedom in vehicle design.

〔Example〕

Next, the present invention will be explained in detail based on some examples.

First, in the first embodiment shown in FIGS. 1 and 2, reference numeral 1 in the figures is, for example, a vehicle lamp, which is formed from a front lens 2 and a rear reflector 3, and has a light bulb 4 serving as a light source in the center of the interior. is installed. The reflecting plate 3 is made of, for example, acrylic resin (refractive index n=1.49).
It is made of a flat transparent material having an appropriate thickness such as
A boundary surface 31 is formed on a flat surface perpendicular to the optical axis C,
The back side corresponding to the boundary surface 31 is made into a completely reflective surface 32 by applying aluminum sputtering, for example. As shown in detail in FIG. 2, the reflective surface 32 is processed with concentric fine prisms (folds) at a predetermined pitch P, and each prism surface extends from the light source to the boundary surface 31. Inclined at a predetermined angle θ so that the light source light, which enters the interior and becomes a refracted ray according to the incident angle λ, becomes an irradiated ray L parallel to the optical axis C after reflection. It has a configuration in which it is formed on a surface.

In other words, when calculating the inclination angle θ of the prism surface, according to Snell's law: sinλ/sini=n...(1) (λ: the incident angle that the incident ray makes with respect to the plane perpendicular to the boundary surface, λ<90゜ i: Refraction angle that the refracted ray makes with respect to a plane perpendicular to the boundary surface) Here, in order for the irradiation ray l to be parallel to the optical axis C, there is a precondition that the boundary surface 31 is perpendicular to the optical axis C. The irradiated light beam l after being reflected from the reflective surface 32 must not be refracted when passing through the boundary surface 31, and must be parallel to the optical axis C at the time of reflection from the boundary surface 31. Therefore, the refraction angle i and the reflection angle i' at the reflecting surface 32 are the same angle, that is, the relationship i=i'.

At this time, as described above, the fact that the irradiated light beam l after being reflected by the reflective surface 32 is parallel to the optical axis C is that
Bisector angle of reflection angle i′ (i.e. refraction angle i) and reflection surface 3
If we form the reflective surface so that , θ=1/2 sin ^-1 (sin λ/n) ...(3) Now, considering the incident angle λ with respect to the boundary surface, in this example, the boundary surface is formed perpendicular to the light source optical axis C. Therefore, this angle λ is determined by the horizontal distance X and vertical distance Y of the boundary surface from the light source center point O, so that the angle λ is (X: Predetermined horizontal distance from the point where the incident ray reaches the boundary surface to the light source optical axis C; Y: Predetermined vertical distance from the point where the incident ray reaches the boundary surface to the horizontal axis passing through the light source center point O) So, by substituting the above equation into equation (3), we get The following relational expression is obtained, and the value of θ is set from the refractive index n of the transparent material and the value as a function of the incident angle λ of the incident light beam L, that is, the distance from the light source center point O.

By the way, in the above embodiment, each prism surface is formed with a desired pitch P, but if the value of θ is set for the refracted ray projected onto the center of the prism surface, the prism surface Although the refracted ray projected onto the edge of the boundary surface 31 is slightly diffused without becoming a parallel ray, for example, when the pitch P is 2.0 mm, when the incident angle λ of the incident ray incident on the boundary surface 31 is around 67°, Diffusion angle is 0.14°, boundary surface 31
When the angle of incidence λ of the incident ray entering the prism is around 45°, the diffusion angle is approximately 0.5°, so the pitch P of the prism surface is equal to the angle of incidence when the refracted ray projected onto the same prism surface enters the boundary surface It is desirable to set the angle of incidence λ of the light rays so that the difference is 1° or less (if the difference is 1°, the light will be diffused by about 0.5°). For this reason,
The diffusion problem can be solved by reducing the pitch of the prism surface as it approaches the light source, and by designing the prism surface so that the difference in incident angle between the refracted rays projected onto both ends of the prism surface is 1° or less.

Further, FIGS. 3 and 4 show a second embodiment of the present invention, in which the boundary surface 31 of the reflector in the first embodiment is inclined at a desired angle α with respect to a plane perpendicular to the optical axis. As in the previous embodiment, the incident angle of the light ray L entering the boundary surface 31 from the light source is γ
Then, according to Snell's law, sinγ/sini=n...(5) However, by setting an inclination angle α to the ray l emitted from this boundary surface 31, Snell's law can be applied. In addition, due to the condition that the light ray l is parallel to the optical axis C, the angle at which the light ray exits from the boundary surface 31 is set to the same angle α as the inclination angle α, thereby satisfying Snell's law on the exit side. The formula is as shown below, sin α/sin j = n (6) Here, the reflection angle when the light ray on the incident side is reflected on the reflective surface 32 is (i + j), and the inclination angle of the reflective surface 32 is As in the previous example, θ should be perpendicular to the bisector of this angle (i+j), and if (i+j)/2=β, then β=i−(θ−α)...(7) β=j+(θ−α) …The relational expression (8) holds true, and by substituting equation (7) into equation (5), β=sin ^-1 (sinγ/n)−(θ−α ) ……(9) is obtained, and by similarly substituting equation (8) into equation (6), β=sin ^-1 (sin α/n) + (θ−α) ……(10 ) is obtained, and from these two equations (9) and (10), the reflecting surface 3
The following equation for determining the inclination angle θ of 2 is obtained.

θ=1/2 [sin ^-1 (sin γ/n) -sin ^-1 (sin α/n)] + α ...(11) Next, the above-mentioned inclination angle θ is determined from the center point of the light source as described in the previous embodiment. Since it is a coefficient of the distance from The relationship is γ = λ - α, and therefore sin γ = sin (λ - α), so by expanding the above equation with the distances X, Y, and Z from the light source center point O, we get the following. A relational expression can be obtained.

(Z: predetermined vertical distance from the point where the extension line of the boundary surface touches the light source optical axis C to the light source center point O) Substituting the above equation into equation (11) yields the following relational expression, and the following relational expression is obtained for this example. The inclination angle θ of the reflecting surface 32 is obtained.

Incidentally, when the angle α is set to zero degrees, that is, when the same state as in the first embodiment is set, the above relational expression naturally becomes as follows, which is the same as equation (4).

[Effects of the Invention] As explained above, the present invention is characterized in that a reflector is formed of a transparent material with a flat boundary surface, and the back surface side corresponding to the boundary surface of the transparent material is made a completely reflective surface, and the back surface The side reflecting surface has a prism surface that reflects the light source light that is formed by refracting the incident light beam that enters the boundary surface and becomes a refracted light beam, and has a predetermined inclination angle θ with respect to a surface perpendicular to the light source optical axis. It is characterized by a prism (folded) process, which allows the thickness of the reflector to be smaller than that of a conventional parabolic surface structure without impairing the irradiation of light parallel to the light source, i.e. The entire device can be made significantly thinner, and the installation space on the vehicle body can be reduced. In addition, if a transparent material with different transparency, such as smoked material, is used to form the reflector, the reflection can be reduced. It has excellent practical effects, such as the ability to freely and easily adjust the amount of light.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional explanatory view showing a first embodiment of a lamp equipped with a reflector according to the present invention, FIG. 2 is an enlarged explanatory view of the main part of the reflector in section A of FIG. 1, and FIG. A half-sectional explanatory diagram showing a second embodiment according to the invention,
FIG. 4 is an enlarged explanatory view of the main part of the reflector in section B of FIG. 3. FIG. 1... Lamp body, 3... Reflector, 31... Boundary surface, 32... Reflective surface, 4... Light bulb, n... Refractive index of reflector, λ... Incident angle, γ... Boundary surface Incident angle when tilted, i, j...Refraction angle, θ...Inclination angle of prism surface, α...Inclination angle of boundary surface, O...
Light source center point, X...Predetermined horizontal distance from the point where the incident ray reaches the boundary surface to the light source optical axis C, Y...
From the point where the incident ray reaches the boundary surface to the light source center point O
A predetermined vertical distance from the point where the extension line of the boundary surface touches the light source optical axis C to the light source center point O.

Claims (1)

[Claims] 1. Made of a transparent material having a predetermined refractive index (n) and having a flat boundary surface on the light source side, the back side of the transparent material corresponding to the boundary surface is formed as a completely reflective surface, The perfect reflection surface is a prism surface that reflects the light source light, which is a refracted light beam by refracting the incident light beam that enters the boundary surface, substantially parallel to the light source optical axis, and the prism surface is parallel to the light source optical axis. A reflector plate formed at a predetermined inclination angle (θ) with respect to a perpendicular plane and satisfying the following formula: In the above equation, X is the predetermined horizontal distance from the point where the incident ray reaches the boundary surface to the light source optical axis C, and Y is the horizontal axis from the point where the incident ray reaches the boundary surface to the horizontal axis passing through the light source center point O. A given vertical distance of Z
is a predetermined perpendicular distance from the point where the extension line of the boundary surface touches the light source optical axis C to the light source center point O, and α is the predetermined inclination angle that the boundary surface makes with respect to a plane orthogonal to the light source optical axis C.