TWI404983B - LED optical fiber coupling system and manufacturing method thereof - Google Patents

Abstract

This invention relates to an LED optical fiber coupling system and a method of manufacturing the same. An LED light source is installed at an inner focal point of a reflection cover having a hyperbolic reflection surface to take advantage of the characteristic in that the hyperbolic reflection surface reflects the lights being incident from the inner focal point outwards along the outer focal point of the hyperbola. An aspheric condenser lens aggregates and projects the reflected lights into a terminal of an optical fiber tube to effectively couple the lights into the optical fiber tube. The lights then propagate inside the optical fiber tube in a total internal reflection method. Thereby, the efficiency of coupling the lights into an optical fiber tube can be improved using the disclosed technology, and the cost can be reduced because making a reflection cover having a hyperbolic reflection surface is easier than making a regular oval reflection cover.

Description

LED fiber coupling system and manufacturing method thereof

The invention relates to an LED fiber coupling system and a manufacturing method thereof, in particular to an LED fiber coupling system applied to distributed illumination and a manufacturing method thereof.

Because LED has the advantages of high brightness, power saving, small size, etc., it is widely used as an illumination source, especially in recent years, and is more commonly used in vehicle lights; however, when the LED is illuminated, there is a limit that the temperature cannot be too high. Therefore, the heat dissipation design of LED lamps must be excellent, otherwise the LEDs are easily damaged.

However, in general, the headlights are mostly placed at the front of the vehicle, and the engine of the vehicle is also placed in the front of the vehicle. Therefore, the temperature of the front is often the highest temperature of the vehicle, and it is not suitable for setting LED lamps.

In order to solve the above problem, a so-called distributed lighting system (DLS) device is applied to a headlight. For example, the US Patent No. 7,215,863 is a light transmitting device, as shown in the fourth figure. The utility model comprises a fiber tube (50) and an LED light source (60), wherein one end of the fiber tube (50) is in communication with an elliptical extension (51), and the two focus systems of the elliptical extension (51) respectively Adjacent to the junction of the elliptical extension (51) and the fiber tube (50) and the free end of the elliptical extension (51), the LED light source (60) is disposed at the adjacent elliptical extension ( 51) the focus of the free end, so when the LED light source (60) emits light, according to the characteristics of the ellipse, the light will pass through the inner wall of the optical fiber tube (50) After being refracted, entering the fiber tube (50) through another focus of the elliptical extension (51), so that the light entering the fiber tube (50) will be in the fiber tube (50). It is continuously transmitted to the other end of the fiber tube (50) in a total reflection manner. In this way, the distributed lighting device can be disposed in the vehicle body to be away from the engine, and only the other end of the fiber tube (50) is disposed at the headlight to transmit the light emitted by the LED light source (60) to the headlight. Shoot out.

However, in order to allow light to enter from one end of the fiber tube (50), it can be totally reflected to the other end of the fiber tube (50), and the light is incident on the fiber tube (50) and is at an angle to the inner wall of the fiber tube (50). It is important that if the requirements of total reflection are not met, the light cannot be transmitted to the other end of the fiber tube (50), resulting in a decrease in the efficiency of the overall coupling; however, since the light is refracted through the elliptical extension (51) The angle of the fiber tube (50) is completely different, so some light cannot be transmitted to the other end of the fiber tube (50), resulting in a decrease in overall coupling efficiency; currently, the existing distributed lighting device can only reach about 40%. Coupling efficiency to 50%.

In addition, the elliptical extension (51) of the above U.S. Patent has a certain degree of difficulty in fabrication because the elliptical extension (51) is not formed in an integrally formed manner. After being divided into two halves, the assembly is superimposed, so that it is difficult to adjust to make the focus of the two semi-elliptical surfaces completely coincide with each other, and the elliptical extension (51) is made at the center because the groove is reserved in the center. The housing of the LED light source (60) is more difficult to process and is therefore more expensive to manufacture.

In addition, the use of parabolic reflectors or elliptical reflectors is not suitable for lens design for the following reasons: When a parabolic reflecting surface is used, the light is emitted from the inner focal point of the paraboloid, and the reflecting surface is emitted in the form of parallel light, which is disadvantageous to the design of the lens. When the elliptical reflecting surface is used, when the light is emitted from the inner focal point of the elliptical surface, The reflective surface will converge to the other inner focus in the same direction, which is not conducive to the design of the lens.

Therefore, further review is needed and a viable solution is sought.

In order to solve the problem that the LED fiber coupling system applied to the distributed lighting device is inefficient and the manufacturing cost is too high, the main object of the present invention is to provide an LED fiber coupling system using a hyperbolic reflector and a collecting lens. To improve the coupling efficiency of distributed lighting devices and reduce manufacturing costs.

A second object of the present invention is to provide a method for manufacturing an LED fiber coupling system, which can quickly complete the design of an LED fiber coupling system by adjusting the distance between the lens and the fiber tube.

It is still another object of the present invention to provide an LED fiber coupling system that can achieve a coupling efficiency of greater than 70% after passing light through a fiber length of one meter.

The main technical means for achieving the foregoing objective is that the LED fiber coupling system comprises: a reflecting cover with a hyperbolic reflecting surface, having an inner focus and an outer focus; and an LED light source facing away from the reflective cover. Hyperbolic reflecting surface At the inner focus of the hyperbolic reflecting surface, the light emitted by the LED light source is reflected by the reflecting cover along the outer focus of the hyperbolic reflecting surface; an aspherical collecting lens is disposed on the LED light source opposite to the reflection The other side of the cover is configured to concentrate the light reflected by the reflector; a fiber tube is disposed on the other side of the aspherical condenser lens opposite to the LED light source, and the light reflected by the reflector is reflected by the aspherical condenser lens A light entrance from the fiber tube is incident and transmitted to the light exit of one of the fiber tubes by total reflection in the fiber tube.

The center point of the reflector, the LED light source, the center point of the aspherical condenser lens, and the light entrance of the fiber tube are on the same optical axis.

In addition, when the hyperbolic reflecting surface reflects the light to the aspherical collecting lens, the incident ray angle of the aspherical collecting lens is the distance from the focal point to the outer focus of the hyperbolic reflecting surface and the curvature of the hyperbolic reflecting surface. It is determined that the distance from the inner focus to the outer focus is in the range of about 0 to 3 mm.

The invention further provides a method for manufacturing the LED fiber coupling system, comprising the steps of: a. adjusting the opening size and curvature of the reflector to adjust the distance between the inner and outer focal points of the hyperbolic reflecting surface; b. The light entrance is set at the focus of the aspherical condenser lens; c. The total internal reflection (TIR) angle and the numerical aperture (NA) value of the fiber tube are calculated according to the characteristics of the fiber tube. Calculate; d. Calculate the required aspheric concentrating lens size according to the TIR angle and NA value of the fiber tube, and match the size of the known reflector opening and its curvature, and the light reflected by the reflector is incident on the aspheric concentrating lens. Angle to calculate the thickness, diameter and aspherical coefficient of the aspherical condenser lens; e. Verify that the coupling efficiency is up to the requirement, and determine whether the light incident on the fiber tube is based on the coupling efficiency value measured from the light exit of the fiber tube The total reflection requirement is reached; if so, the system design is completed, otherwise the following steps are performed; f, after adjusting the distance between the fiber tube and the aspherical condenser lens, proceed to step e.

The efficiency of coupling light to the fiber tube can be improved by using the prior art, and the manufacturing cost is reduced by making the hyperbolic reflecting surface reflector more convenient than making an elliptical reflector.

For a preferred embodiment of the present invention, as shown in the first figure, a reflector (10), an LED light source (20), an aspherical condenser lens (30), and a fiber tube (40) are included. .

The reflector (10) has a hyperbolic reflecting surface (11). According to the hyperbola characteristic, the hyperbolic reflecting surface (11) has an inner focus and an outer focus inside and outside the reflecting cover (10). Since the hyperbolic reflecting surface (11) is manufactured, the reflecting surface conforming to the hyperbolic characteristic can be completed in only one process, so that the elliptical reflecting surface of the distributed illuminating device must be manufactured in two processes. a reflection with two focal points in the ellipse Therefore, the reflector (10) of the present invention has a low manufacturing cost.

The LED light source (20) is facing away from the reflector (10) and disposed at an inner focus of the hyperbolic reflecting surface (11). Thus, according to the characteristics of the hyperbola, the LED light source (20) is emitted. The light rays will be reflected by the hyperbolic reflecting surface (11) along the outer focus of the hyperbolic reflecting surface (11), so that the virtual light is disposed on the other side of the reflecting cover (10). The point light source (20') emits light; in this embodiment, by adjusting the opening size of the hyperbolic reflecting surface (11) of the reflecting cover (10), the LED light source (20) and the virtual light can be designed accordingly. The spacing between the point sources (20') is below 3 mm.

The aspherical condenser lens (30) is disposed on the other side of the LED light source (20) opposite to the reflector (10) to concentrate the light reflected by the reflector (10).

The fiber tube (40) is disposed on the other side of the aspherical condenser lens (30) opposite to the LED light source (20), and the light reflected by the reflector (10) is used by the aspherical condenser lens (30). A light entrance (41) of the fiber tube (40) is incident and transmitted to the light exit of one of the fiber tubes (40) by total reflection in the fiber tube (40) (not shown); In the fiber tube (40), the light must be totally reflected at the junction of the core and the cladding of the fiber tube (40), and the light that meets the fiber tube (40) is satisfied. The ratio of total reflection conditions, in this embodiment, is adjusted by adjusting the distance between the aspherical condenser lens (30) and the fiber tube (40) so that the light conforms to the total internal reflection of the fiber tube (40) ( Total internal reflection (TIR) is a range of angular and numerical aperture (NA) values that are incident on the fiber tube (40), and The total reflection transmission can be performed in the fiber tube (40); as shown in the second figure, the light pattern drawn from the light exit of the fiber tube (40), which is illustrated as a hyperbolic reflection surface (11) The reflectivity is 0.92, and the transmittance of the non-spherical lens is 0.9025. The overall coupling efficiency can reach 77.66%.

Wherein the numerical aperture value is defined as a sinusoidal function value of a half-angle of a maximum incident angle of a light beam incident on the optical fiber and stably transmitted therein.

It can be seen from the above that after the light emitted by the LED light source is reflected by the reflector, it is like a light emitted by the LED light source disposed at the outer focus of the reflector, and the aspherical condenser lens is used to match the light to the total reflection. The angle is concentrated into the fiber tube, and the angle of the light entering the fiber tube can be adjusted by designing the curvature of the aspherical condenser lens and the distance between the aspherical lens and the fiber tube to improve the incidence of the light into the fiber tube. The ratio of the total reflected light, thereby increasing the coupling efficiency of the light; in addition, since the hyperbolic reflecting surface is easier to process than the elliptical reflecting surface, the manufacturing cost of the present invention is reduced.

Referring to the first figure and with reference to the third figure, the present invention further provides a method for manufacturing the LED fiber optic convergence system, comprising the steps of: a. adjusting the opening size of the reflector and its curvature (300) to adjust the double The distance between the focal point and the inner focus of the curved reflecting surface (11) is less than 3 mm; b. the light entrance of the fiber tube is set at the focus of the aspherical collecting lens (301); c. calculating the TIR angle of the fiber tube and The NA value (302) is calculated based on the characteristics of the fiber tube (40). The algorithm for the NA value is based on the formula: n _c0 : core refractive index, n _c1 : fiber refractive index

Therefore, the NA value can be derived from the characteristic values n _c0 and n _{c1 of the} optical fiber, and the angle value of θ _n can be known. As can be seen from the above formula, the NA value is only a function of the core refractive index n _c0 and the fiber refractive index n _c1 . Therefore, the coupling efficiency of the fiber and various components is directly affected by whether the NA values of each other are matched. In addition, if the TIR angle is θ _t , the calculation method is as follows according to the law of refraction: n _c0 sin θ _t = n _c1 sin θ ₁ θ _t : TIR angle, θ ₁ : preset angle of total reflection (90 degrees)

Since it is intended to achieve total reflection, θ _{1 is} preset to 90 degrees, so sin θ ₁ =1, so n _c0 sin θ _t =n _c1 , that is, sin θ _t =n _c1 /n _c0 , thereby obtaining the TIR angle The value θ _t =sin ^-1 (n _c1 /n _c0 ); d. Calculate the required aspheric concentrating lens size (303), based on the TIR angle and NA value of the fiber tube (40), with the known reflection The size of the opening of the cover (10) and its curvature, the angle of the light reflected by the reflector (10) incident on the aspherical condenser lens (30), that is, the NA value obtained by the incident angle θ _{I of the} light and the step c The angle θ _{n is} derived, and the light exit angle θ _{o of the} aspherical condenser lens (30) is reversed to calculate the thickness, diameter and aspherical coefficient of the aspherical condenser lens, and the aspherical condenser lens is 30) The characteristics meet the requirements; e. Verify that the coupling efficiency meets the requirement (304), and determine whether the light incident on the fiber tube (40) reaches total reflection based on the coupling efficiency value measured from the light exit of the fiber tube (40). Requirements; if yes, complete the system design, otherwise proceed with the following steps; f adjust between the fiber tube and the aspheric condenser lens The distance (305) is adjusted by adjusting the distance between the fiber tube (40) and the aspherical condenser lens (30) by moving the fiber tube (40), and then proceeding to step e.

After the above design, the coupling efficiency of the fiber coupling system of the present invention can be higher than 70% after passing through the fiber tube (40) of one meter length.

However, the present invention has been disclosed in the foregoing embodiments, but is not limited to the contents mentioned in the foregoing embodiments, and any changes and modifications made without departing from the spirit and scope of the invention belong to the protection of the present invention. range.

In summary, the present invention has been significantly improved in effectiveness, and meets the requirements of the invention patent, and filed an application in accordance with the law.

(10) ‧‧‧reflector

(11) ‧‧‧ hyperbolic reflective surface

(20)‧‧‧LED light source

(20') ‧ ‧ virtual point source

(30)‧‧‧Aspheric concentrating lens

(40) ‧‧‧Fiber tube

(41) ‧‧‧Light entrance

(50) ‧‧‧Fiber tube

(51)‧‧‧Oval extension

(60)‧‧‧LED light source

First Figure: A side view and partial cross-sectional view of a preferred embodiment of the present invention.

Second Figure: A light pattern drawn from the exit of a fiber optic tube of a preferred embodiment of the present invention.

Third FIGURE: A flow chart of a method of fabrication from a preferred embodiment of the present invention.

Figure 4: A side view of a light transmitting device of the U.S. Patent No. 7,215,863.

(10) ‧‧‧reflector

(11) ‧‧‧ hyperbolic reflective surface

(20)‧‧‧LED light source

(20') ‧ ‧ virtual point source

(30)‧‧‧Aspheric concentrating lens

(40) ‧‧‧Fiber tube

(41) ‧‧‧Light entrance

Claims (6)

An LED fiber coupling system includes: a reflecting cover with a hyperbolic reflecting surface, having an inner focus and an outer focus; an LED light source, a hyperbolic reflecting surface facing away from the reflecting cover, and disposed on the double An inner focus of the curved reflecting surface, wherein the light emitted by the LED light source is reflected by the reflecting cover along the outer focus of the hyperbolic reflecting surface; an aspherical collecting lens is disposed on the LED light source opposite to the reflective cover a side of the light to be concentrated by the reflector; a fiber tube is disposed on the other side of the aspherical concentrating lens opposite to the LED light source, and the aspherical concentrating lens reflects the light reflected by the reflector from the optical fiber A light entrance of the tube is incident and transmitted to the light exit of one of the fiber tubes by total reflection in the fiber tube. The LED fiber coupling system according to claim 1, wherein the distance between the two focal points of the hyperbolic reflecting surface of the reflector is 3 mm or less. The LED fiber coupling system of claim 2, wherein the fiber tube is located at a focus of the aspherical condenser lens. A method for manufacturing an LED fiber coupling system according to claim 1, comprising the steps of: a. adjusting an opening size of the reflector and a curvature thereof to adjust a distance between the inner and outer focal points of the hyperbolic reflecting surface; b. placing the light entrance of the fiber tube on the focus of the aspherical condenser lens; c. Calculate the total internal reflection (TIR) angle and numerical aperture (NA) value of the fiber tube, which is calculated according to the characteristics of the fiber tube; d. Calculate the required aspherical condenser lens The specification is based on the TIR angle and the NA value of the fiber tube, and the angle of the opening of the reflector and the curvature thereof are used, and the angle of the light reflected by the reflector is incident on the aspherical condenser lens to calculate the aspherical condenser lens. Thickness, diameter and aspherical coefficient; e. Verify that the coupling efficiency meets the requirements, and determine whether the light incident on the fiber tube meets the total reflection requirement based on the coupling efficiency value measured from the light exit of the fiber tube; if so, complete the system design Otherwise, the following steps are performed; f, after adjusting the distance between the fiber tube and the aspherical condenser lens, proceed to step e. The method of manufacturing the LED fiber coupling system of claim 1, wherein the inner and outer focal lengths of the hyperboloid are less than 3 mm. The method for manufacturing the LED fiber coupling system according to Item 1 or 4 of claim 4, wherein the design of the aspherical condenser lens is mainly based on the NA value and the TIR angle, wherein , TIR angle = θ _t = sin ^-1 (n _c1 / n _c0 ), and n _{c0 is} the refractive index of the core of the fiber tube, and n _{c1 is} the refractive index of the fiber of the fiber tube.