JPH087615A - Light distributing structure having auxiliary reflector - Google Patents

Abstract

PURPOSE:To improve an effective utilization factor of a light flux emitted from a light source by improving a light distributing structure. CONSTITUTION:Plural spheroidal reflectors 21a and 21b has respectively a first focus Pv and a second focus P2, and have the first focus P1 in common with each other. Light guides 22a and 22b are installed in the major axis direction of the spheroidal reflectors. Reflected light reflected by the spheroidal reflector 21a by emitting from a light source 5 as arrows (h, i and j) is condensed on the second focus P2, and passes, and is re-reflected by an auxiliary reflector 23a, and reaches a light receiving surface of the light guide 22a. An incident angle (theta1) of this re-reflected light on the light receiving surface of the light guide 22a is set not more than 1/2 of a critical angle of optical fiber constituting the light guide 22a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for distributing light emitted from a single light source to a plurality of light guides and guiding the light to a lamp by each of the plurality of light guides.

[0002]

2. Description of the Related Art As a technique for distributing a light beam emitted from a single light source to a large number of light guides and guiding it to a lamp, Japanese Patent Application Laid-Open No. HEI-2 is proposed.
A centralized illumination system using a high brightness light source of No. 172102 is known. FIG. 4 shows the above known example. The special bulb 1 shown in FIG. 1A is made of hard glass, and the discharge light emitting mechanism is enclosed in the special bulb 1 and is fed by the lead wires 1a and 1b. A large number (five in this example) of light guides 1c to 1g are formed in the special tube 1, and the light generated by the discharge is distributed and led out by these light guides. As shown in FIG. 2B, a large number of light guides 1c-1c are provided.
The light guided in g is the optical fibers 2c to 2g, respectively.
Are led to the respective lamps 3c to 3g (the lamps 3d and 3e are not shown in the figure). In the above-mentioned known example, the special tube 1 is required, and this member is not versatile, which is inconvenient for practical use. By eliminating such inconvenience and making it possible to use a commercially available light source bulb, FIG.
The configuration of is also proposed. The rotating parabolic mirror 4 shown in FIG.
The light source 5 is installed at the focal point F of. As the light source 5, for example, a commercially available mercury discharge lamp can be used, and it can be attached / detached and replaced. Light incident on the paraboloidal mirror 4 from the light source 5 is reflected parallel to the optical axis Z as indicated by arrows a, b, and c.
A large number of optical fibers 6 are arranged so as to face the parallel light flux, and each of the light fluxes is incident and guided to a desired position (a lamp not shown) 7 is a glass rod for absorbing heat rays.

In the prior art shown in FIG. 5, the parallel luminous flux reflected by the rotating parabolic mirror 4 has a uniform luminous flux distribution density. Therefore, a large number of optical fibers 6 are evenly distributed in the amount of light. Depending on the application of this light distribution mechanism, the above-mentioned uniform distribution function may be convenient, but it is not suitable for unifying the light source of a vehicle lamp, for example.
Generally, a vehicle is equipped with a large number of lamps, a headlight and a stop lamp require a relatively large amount of light, and a tail lamp and a small lamp require a small amount of light. Therefore, if the conventional example of FIG. 5 is applied to a vehicular lamp and the light emission of the light source 5 is evenly distributed, the headlamps and the stop lamps lack the light amount supplied, and the tail lamps and the small lamps supply the light amount. Is too large, there is a problem that the light must be dimmed by the optical filter. A light distribution structure shown in FIG. 6 is conceivable as a light distribution structure capable of intentionally distributing the light amount to a large number of light guides by solving the above-mentioned problems. This structure was created by the present inventors and will be referred to as a tentative plan hereinafter. FIG. 6 (A) is a side view, and FIG. 6 (B) is a BB arrow view thereof. 8 is a spheroidal mirror, f ₁ is its first focal point, f ₂ is also its second focal point, Z
Is also the optical axis. The light source 5 is arranged near the first focal point. In this proposal, the light source was composed of a mercury discharge tube.

The spheroidal mirror 8 is emitted from the light source 5 described above.
The light flux reflected at is focused on the second focal point f ₂ as shown by arrows d and e, intersects, and then diffuses. A convex lens 9 is provided at a position for receiving the diffused light, and the light is condensed to form a parallel light flux as indicated by arrows d'and e '. A convex lens having such a function is widely used as an aspherical convex lens for a projector-type headlight, for example. Since FIG. 6A is vertically symmetrical with respect to the optical axis Z, the arrow mark is attached to only one side. A large number of light guides 6 are arranged so as to face the parallel light beams d'and e '. The BB arrow view is as shown in FIG. The distribution density of the parallel light flux is dense in the central portion and sparse in the peripheral portion. By using this, a light guide that guides light to a large amount of light such as a headlight or a stop lamp is arranged in the center as shown in 6a of FIG. 6B, and a small amount of light such as a small lamp or a tail lamp is arranged. The light guide for guiding the light to the lamp is arranged at the peripheral portion as shown in 6b of FIG. Accordingly, it is possible to distribute light to each of the lamps without excess or deficiency. Also, FIG.
In the prior art shown in (1), when the number of optical fibers 6 to be arranged is increased, the rotary parabolic mirror 4 is replaced with one having a large diameter to increase the diameter of the parallel light flux (arrows a, b, c). Although it had to be done, in the trial shown in FIG. 6A, the convex lens 9 is replaced with a large diameter lens without moving the spheroidal mirror 8 and the large diameter lens is moved forward of the lamp. Since the diameter of the parallel light flux (arrows d ', e') increases, the number of light guides 6 arranged can be increased.

The light distributing device according to the tentative plan shown in FIG. 6 has an excellent effect that the number of the light guides 6 arranged can be easily changed, but the convex lens 9 is a relatively heavy component member. In addition, the convex lens 9 absorbs light and causes a loss due to surface reflection of light. Comparing the problems of the conventional example shown in FIG. 4, the known example shown in FIG. 5 and the trial example shown in FIG. 6, the conventional example shown in FIG. 4 uses a special bulb, so that it is not easy to replace the light source bulb. In the known example of FIG. 5, it is not easy to change the number of light guides to be installed, and the tentative plan of FIG. 6 is heavy because a convex lens is provided. In order to solve the above problems, a light distribution structure as shown in FIG. 7 has been proposed and is well known.
The structure shown in FIG. 7 is a device created by the present inventor and applied for separately (actual application No. 4-55689, hereinafter referred to as a device of the prior application). FIG. 6 is a perspective view corresponding to one example of a light distribution structure according to the present invention. A pair of spheroidal mirrors 8A and 8B are opposed to each other and fixed to each other. In this example, it is fixed with a mounting screw 8C via a short cylindrical adapter 12. The light source 5 is installed in the space surrounded by the pair of spheroidal mirrors 8A and 8B. In this example, a discharge lamp burner was used as the light source. Reference numeral 10 drawn by a solid line is a socket of the light source 5. The light source socket may be provided at the position 10 'shown by the phantom line.
Reference numeral 11 is a power supply harness. The light receiving portions of a plurality of (five in this example) light guides 9a to 9d fixed to the short cylindrical adapter 12 are arranged radially at equal intervals in the circumferential direction. Each of these light guides is connected to a lamp (not shown). Z is a spheroidal mirror 8A,
It represents the optical axis of 8B. The light emitted from the light source 5 is
In the space surrounded by the pair of spheroidal mirrors 8A and 8B repeatedly and surrounded by the pair of spheroidal mirrors 8A and 8B, light in all directions is distributed with a uniform luminous flux density. (Speaking figuratively, this space is filled with light). Therefore, equal light amounts are derived from the light guides 9a to 9b. Since this embodiment (FIG. 7) is substantially symmetrical with respect to the optical axis Z, the light distribution amount of each light guide becomes uniform with high accuracy. Further, as can be easily understood from this operation, the number of light guides to be installed can be set arbitrarily, and the degree of freedom in design is large. Also,
When the light source (for example, a discharge lamp) is worn, the mounting screw 8C can be removed and replaced easily. Further, as is apparent from this embodiment, since no convex lens is used, the weight can be reduced. As described above, the invention of the prior application shown in FIG. 7 is a recent and most advanced publicly known technology relating to the light distribution structure, and (a) is lightweight because it does not use a convex lens. ) Light emitted from a single light source can be distributed to multiple light guides, and (c) the number of light guides can be set arbitrarily, and (c) the amount of light for each light guide. Is evenly distributed.

[0006]

The inventors of the present invention applied for the light distribution structure according to the invention of the prior application shown in FIG. Although it was confirmed that the effect was obtained, it was found that there was room for improvement in the following points, and this was confirmed.
That is, although there are various types of optical fibers forming the light guide, one of the optical characteristic values of each type of optical fiber is the critical angle of the incident angle on the light receiving surface. Incident light that exceeds this critical angle may be totally reflected by the light-receiving surface, or may not be guided in a correct state even if it enters the optical fiber. In the invention of the prior application (FIG. 7), since the incident angle of the light incident on the light receiving surfaces of the light guides 9a to 9e could not be controlled, the light having the incident angle exceeding the critical angle could not be effectively derived. There was a limit to the improvement of the effective utilization rate of the luminous flux. Further, in the prior art shown in FIG. 6, the light flux emitted from the light source 5 and not incident on the spheroidal mirror 8 (the light flux emitted in the range of the solid angle ω shown in FIG. 6) is not effectively used. The luminous flux effective utilization rate of the entire light distribution structure is not high. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light distribution structure having a novel structure in which the effective utilization rate of a light beam emitted from a light source is high.

[0007]

SUMMARY OF THE INVENTION The basic principle of the present invention created to achieve the above-mentioned object (improvement of effective utilization of luminous flux) is outlined with reference to FIG. Then, 21a and 21b are spheroidal reflectors, respectively, having the first focal point P ₁ and the second focal point P ₂ and sharing the first focal point P ₁ . The light source 5 is arranged at the first focal point P ₁ and the arrows h, i,
The luminous flux emitted as j is the spheroidal reflector 21a.
It is reflected by and is condensed at the second focal point P ₂ . The light passing through the second focal point P ₂ is re-reflected by the auxiliary reflector 23a toward the light receiving surface of the light guide 22a. The auxiliary reflector 23a is formed in an appropriate shape (detailed later with reference to FIG. 2) so that the angle θ _{1 at} which the re-reflected light path is incident on the light receiving surface of the light guide 22a is smaller than the critical angle. . In order to achieve the above-mentioned object (improvement of effective utilization rate) based on the above-mentioned principle, the light distribution structure according to the present invention has a plurality of spheroidal reflectors each having a first focus and a second focus. The light receiving portion of the light guide is arranged along the line extending from the major axis of the spheroidal reflector in the direction of the second focal point. Provided is an auxiliary reflector that emits from a light source with one focus, is reflected by a spheroidal reflector, is condensed at a second focus, and then reflects the light flux passing through the second focus toward the light receiving portion of the light guide. The incident angle θ ₁ at which the light beam reflected by the auxiliary reflector is incident on the light receiving surface of the light guide is equal to or less than ½ of the critical angle of the optical fiber forming the light guide. Is set And are characterized.

[0008]

According to the above-mentioned means, although the direction of the light beam reflected by the spheroidal reflector is not constant, it is condensed at the second focus and passes through the second focus. The light flux passing through the second focal point is re-reflected by the auxiliary reflector and is incident on the light-receiving surface of the light guide at an incident angle equal to or less than the critical angle. Therefore, the light flux that has reached the light receiving surface of the light guide is not totally reflected but is incident on the light guide and is effectively used.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, referring to FIGS.
An embodiment of the present invention will be described. FIG. 1 is a view showing a light distribution structure provided with an auxiliary reflector according to the present invention, and is a view in which an optical path arrow is added to a cross-sectional view schematically illustrating a main part. For convenience of explanation, orthogonal coordinate axes Y and Z are assumed as shown. 21
a, 21b, the first focal point P ₁ respectively a spheroidal reflector having a second focal point P _2, are provided consecutively brought match first focal point P ₁ to each other, the second focal point P _2, respectively It is located on the axis Z. That is, the previous axis Z coincides with the major axis direction of the ellipse. In the figure, A is the major axis dimension, and B is the minor axis dimension. Along the extension line of the long axis of the spheroidal reflector, that is, on the Z axis, the light guide 22a,
22b is installed. Between the first focus P ₁ and the second focus P ₂ , a concave mirror type auxiliary reflector 23a,
23b are arranged so that their convex surfaces face the first focal point, that is, their reflective surfaces face the second focal point P ₂ and the light guide surfaces of the light guides 22a and 22b face. The above-mentioned auxiliary reflectors 23a and 23b are respectively
The light guides 22a and 22b pass the light flux that has passed through the second focus.
It is re-reflected toward the light receiving surface of so that the incident angle θ ₁ is less than half the critical angle. In carrying out the present invention, the incident angle of the re-reflected light is required to be 1/2 or less of the critical angle, and the incident angle θ ₁ is 0 <2θ ₁ <critical angle .... (1) It is allowed to change within the range of the above formula (1).
The incident angle cannot be 0 or less, and the fact that the incident angle is half or less of the critical angle is indispensable for achieving the object of the present invention. Therefore, the numerical limitation of the above formula (1) is theoretical. It is based on grounds. This permissible angle range is quite wide from the viewpoint of precision optics. That is, for example, when the optical fiber is made of quartz glass and the critical angle is about 15 degrees, it has a wide allowable range of 0 ° <θ ₁ <7.5 ° (2). . Therefore, the shapes of the auxiliary reflectors 23a and 23b such that the incident angle θ ₁ of the re-reflected light shown in FIG. 1 falls within the range of the above-mentioned formula (2) specify this by an analytical geometric formula. The fact is that
It is extremely difficult, and according to modern optical technology, "a light beam re-reflected by an auxiliary reflector is incident on the light-receiving surface of the light guide at an incident angle of less than half the critical angle,
The shape of the reflecting surface of the auxiliary reflector can be configured in any way, and is a matter of design consideration. The auxiliary reflector of this embodiment was designed by the following design so that the incident angle of the re-reflected light incident on the light guide would be an angle θ ₁ ′ smaller than the critical angle. FIG. 2 is a diagram showing a design procedure for obtaining the three-dimensional shape of the auxiliary reflector in FIG. 1 described above, in which FIG.
(B) is a method of converting the above Z-axis into coordinates to obtain the line segment M ', and (C) is rotating the above-mentioned line segment M'about the axis Z to form a reflection surface. The respective methods for obtaining the rotating surface to be configured are shown. As shown in FIG. 2 (A), a line segment M consisting of a parabola whose axis is the axis Z and whose focal point is the second focal point P ₂ is defined. As shown in FIG. 2 (B), with respect to the second focal point P ₂ , the line segment M is divided by the angle θ ₁ ′.
Just rotate. The axis Z ′ shown in the drawing is the angle θ ₁ ′ with respect to the axis Z.
The figure shows the shape when it is rotated only by the angle.
_It represents a line segment M consisting of a parabola rotated by ₁ '. Due to this rotation, the vertex P ₃ of the parabola M becomes the point P ₃ ′.
Move to. A point P ₃ ″ shown is a point where a line segment M ′ after rotation (shown by a broken line and formed of a parabola) intersects the axis Z. In FIG. 2B, it is formed by a rotated parabola. The line segment M ′ is located above the Z axis (that is, the part above the point P ₃ ″ is considered, and an arc arrow centering on the axis Z as shown in FIG. φ
As described above, the line segment M ″ describes a plane of rotation. Assuming that the axis Z ′ is also rotated together with the above-described rotation, the axis Z ′ is Z ′, Draw a cone as represented by Z ". However, this FIG. 2C is a schematic view so that it is easy to infer a three-dimensional shape, and is not an accurate plan view. (If you draw correctly, the bottom of the rotating body will be a straight line, not a vertically elongated ellipse like this figure). Figure 2
As can be easily understood from the fact that the drawing process described above with respect to FIG. 2A starts from the parabola in FIG. 2A, the light flux passing through the second focus in FIG. When it reaches L'and is re-reflected by the rotating body, it becomes a re-reflected light flux parallel to the line Z'-Z '. Similarly, "when it is re-reflected by the line Z" point L of the virtual becomes re-reflected light beam parallel to the -Z ". That is, the crossing angle with respect to the axis Z corners theta ₁ '
And this angle θ ₁ ′ is set smaller than the critical angle. As a result, the re-reflected light flux is transmitted to the light guide 22a,
The light is incident on the light receiving surface 22b (see FIG. 1) at an incident angle smaller than the critical angle, and is effectively used. In the embodiment of FIG. 1, the two spheroidal reflectors 21a and 2ab are provided so that the first focus P ₁ is shared, but the number of the spheroidal reflectors 21a and 2ab can be set to an integer N of 3 or more. Accordingly, the number of installed light guides and auxiliary reflectors is also N.

FIG. 3 is an enlarged view schematically showing the vicinity of the light receiving portion of the light guide described in the embodiment shown in FIG. 1 above and schematically drawn to show the critical angle of the optical fiber and the incident angle from the auxiliary reflector. It is the figure which compared and was filled in. The optical fiber 24 forming the light guide 22a has a critical angle θ ₂ as a characteristic value, and a light beam incident obliquely beyond this angle range is not effectively guided by the optical fiber 24. On the other hand, the re-reflected light from the auxiliary reflector is incident angle θ ₁
Reaches the light receiving surface of the light guide 22a. Here, the incident angle θ ₁ is smaller than half the sea angle according to the above-mentioned formula (1). Therefore, the re-reflected light enters the light guide 22a and is effectively guided.

[0011]

When the present invention is applied, the direction of the light beam reflected by the spheroidal reflector is not constant, but it is condensed at the second focal point and passes through the second focal point. The light flux passing through the second focal point is re-reflected by the auxiliary reflector and is incident on the light-receiving surface of the light guide at an incident angle equal to or less than the critical angle. Therefore,
The light flux that has reached the light receiving surface of the light guide has an excellent practical effect of being incident on the light guide and being effectively used without being totally reflected.

[Brief description of drawings]

FIG. 1 is a view showing a light distribution structure provided with an auxiliary reflector according to the present invention, in which an optical path arrow is added to a cross-sectional view schematically illustrating a main part.

FIG. 2 is a diagram showing a design procedure for obtaining the three-dimensional shape of the auxiliary reflector in FIG.
Is a target curve for the Z axis, and (B) is a method for determining the line segment M ′ by coordinate conversion into a form in which the Z axis is rotated.
(C) represents a method of rotating the line segment M ′ around the axis Z to obtain a rotation surface forming a reflection surface.

FIG. 3 is a magnified view schematically showing a light receiving portion of the light guide described in the embodiment shown in FIG. 1 above, which is drawn in an enlarged manner and shows the critical angle of the optical fiber and the incident angle from the auxiliary reflector. It is the figure filled in contrastingly.

FIG. 4 is a perspective view showing a known example of a light distribution structure.

FIG. 5 is a schematic side view showing a known example different from the above.

6A and 6B show a tentative plan relating to a light distribution device, FIG. 6A is a schematic side view, and FIG. 6B is a BB cross-sectional view thereof.

FIG. 7 is an external perspective view schematically showing an embodiment of a light distribution structure according to the invention of the prior application.

[Explanation of symbols]

1 ... Special tube, 2 ... Optical fiber, 3 ... Lamp, 4 ... Rotating parabolic mirror, 5 ... Light source, 6 ... Optical fiber, 7 ... Glass rod, 8, 8A, 8B ... Spheroidal mirror, 9 ... Convex lens,
9a to 9e ... Light guide, 10 ... Socket, 11 ... Harness, 21a, 21b ... Spherical surface reflector, 22
a, 22b ... Light guide, 23a, 23b ... Auxiliary reflector.

Claims (1)

[Claims] 1. A plurality of spheroidal reflectors each having a first focal point and a second focal point are arranged so that their respective first focal point positions are aligned with each other. The light-receiving portion of the light guide is arranged along a line extending in the direction toward the second focal point, and the light is emitted from the light source at the first focal point, reflected by the spheroidal reflector, and condensed at the second focal point. After that, an auxiliary reflector for reflecting the light flux passing through the second focal point toward the light receiving portion of the light guide is provided, and the light flux reflected by the auxiliary reflector is incident on the light receiving surface of the light guide. The light distribution structure provided with an auxiliary reflector, wherein the angle θ ₁ is set to be equal to or less than ½ of a critical angle of the optical fiber forming the light guide.