JPH0312601A - Optical component which uniforms luminous flux - Google Patents

Abstract

PURPOSE:To uniform luminous flux with high efficiency by laminating specific two kinds of transparent plates alternately while forming a layer which has a lower refractive index than those transparent plates between them. CONSTITUTION:A Y axis is set in parallel to a side where plural prism units are formed, an X axis is set in parallel to a side perpendicular to said side, and a Z axis is set in a plate thickness direction. Then, a transparent plate 1 of a both-side saw-tooth shape where prism units satisfies the condition that angles theta - -theta are formed by the X axis and expressions I and II, and, on a couple of opposite sides, plural prism units are formed, and a rectangular transparent plate 7 whose sides are as long as those of the transparent plate 1, are laminated alternately while the layer 8 having the lower refractive index than the transparent plates 1 and 7 is formed between them. In the expressions, deltais an angle which is smaller between the divergence angle of incident luminous flux and the divergence angle (+ or -delta) that the device which uses projection luminous flux can uses and less than theta, and (n) is the refractive index of the transparent plate 1. Consequently, the uniform luminous flux with high efficiency can be obtained.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a uniform and unidirectional light flux required for the light incident portion of an optical fiber light guide, the illumination light source of a slide projector, etc. Regarding optical components that obtain.

[Prior art] Line light sources used in defect inspection equipment for sheet materials,
Optical fiber light guides are used as cold light sources for LCD backlights in LCD printers, but in order to obtain high-quality illumination without illuminance pressure, these light beam incident areas are equipped with a light guide to make the incident light uniform. Devices using a diffuser plate or an optical fiber and a light guide as described in Japanese Patent Application No. 63-106779 have been devised.

Additionally, an optical system using a relay condenser is generally used in the light source section of a slide projector to prevent uneven brightness throughout the projected image.

[Problems to be Solved by the Invention] The following conditions are required for these light source units or light source uniformity means.

(1) The amount of light is uniform throughout.

(2) High efficiency.

Furthermore, considering cost and practicality, (3) Easy to design and produce.

(4) It is small and does not take up much space.

Things are also important.

The method using the above-mentioned diffusion plate and the patent application No. 1067-1983
The method using optical fibers and light guides in No. 79 uses reflective curved surfaces and lenses to create a directional light beam, which is passed through a homogenizing component to remove brightness irregularities, but the former uses a diffuser. The angle at which the light rays are scattered by the plate is wide (,
The efficiency is extremely low because the beam properties of the light are impaired and the light that does not fit within the aperture angle of the optical fiber becomes a loss. On the other hand, the contactor has good uniformity performance and is efficient without impairing the beam properties of the light, but it is difficult to miniaturize, and the random mixing method is not easy to mass produce while maintaining quality.

Furthermore, the optical system using the relay condenser mentioned above has good uniformity performance (although the efficiency is not very bad), but the design and adjustment of the light bulb, reflector, condenser lens, etc. used must be carefully done, and the technology is required.

Therefore, within the scope of the prior art, it is difficult to realize an optical system that simultaneously satisfies the conditions (1) to (4) above.

[Means for Solving the Problems] In view of the above-mentioned problems, an object of the present invention is to provide an optical component that can be miniaturized and can uniformize the luminous flux with high efficiency.

In order to achieve the above objects, as shown in FIGS. 1 to 4 and 10, an optical component for uniformizing the luminous flux of the present invention having the following features is provided.

That is, the optical component for uniformizing the luminous flux according to the first aspect of the present invention satisfies the following condition A and includes a biserrated transparent plate l in which a plurality of prism units are formed on a pair of opposing sides, and the transparent plate 1 and rectangular transparent plates 7 having the same side length are alternately laminated with layers 8 having a lower refractive index than those of the transparent plates 1.7 being formed between them.

(Condition A) When the Y-axis is parallel to the side on which multiple prism units are formed, the X-axis is parallel to the side perpendicular to this, and the Z-axis is in the plate thickness direction,
The prism unit forms an angle θ to 10 with the X axis as expressed by the formula {1}{2}.

However, δ: the spread angle of the incident light flux or the spread angle (±δ) that can be used by the device that uses the output light flux, whichever is smaller - θ n: the refractive index of the transparent plate l. By a method such as applying metal plating to at least one of the mutually contacting surfaces of the transparent plate 1 and the transparent plate 7 of item 1, or sandwiching a metal plated film or metal foil between them, This is an optical component that is laminated to include a metal reflective surface between the eyebrows.

Furthermore, the third aspect of the present invention is an optical component in which the two sawtooth transparent plates l of the first aspect are laminated in parallel at intervals.

The present invention can be used, for example, in a method similar to the method described in Japanese Patent Application No. 63-106779, in which a directional light beam is created using a reflective curved surface or a lens, and this is passed through a uniformizing component to remove brightness irregularities. This is a luminous flux equalizing component, which has the feature of uniformizing the amount of light without impairing the beam properties of the luminous flux, similar to the method described above.

This feature is important for obtaining high efficiency, because whether it is a fiber optic light guide or a slide projector, the light beam that spreads at an angle beyond the aperture angle of the optical system installed later is not utilized and is lost. Although the light source does not need to be parallel light, it is desirable that the light beam be unidirectional.

[Function] Hereinafter, the function of the optical component used in the present invention will be explained with reference to the drawings.

First, the function of the double sawtooth transparent plate 1 of the present invention will be explained using FIG.

FIG. 1(a) is a view of the double-serrated transparent plate 1 viewed from the Z-axis direction, and FIG. 1(b) is a perspective view thereof. transparent plate 1
30 prism units are placed on two opposing sides of a rectangular transparent plate of equal thickness.
A large number of prism units 30 form a pair of surfaces in the plate thickness direction, one of which is the light entrance surface 20 and the other is the light exit surface 22.
It is configured so that In FIG. 1, the rectangle has a horizontal length W and a vertical length L, and a prism unit 30 is formed on the long sides. A side 6 perpendicular to the side forming the prism unit 30 is a reflective surface, as will be described later.

Here, when the Y-axis is parallel to the side on which a plurality of prism units 30 are formed, the X-axis is parallel to the side perpendicular to this, and the two axes are in the thickness direction of the plate, light incident parallel to the X-axis Think about 1i14.

In each prism unit 30 on the entrance surface 20,
The plane that forms an angle with the axis is called the +0 plane (represented by 3 in the figure), and the plane that forms -0 is called the 1θ plane (represented by 2 in the figure). The plane parallel to the plane will be called the +0 plane, and the plane parallel to the -0 plane will be called the -0 plane. The light beam incident on the +0 plane changes its direction by an angle α that satisfies Equation 0 due to refraction, and reaches the exit plane 22 separated by L tan α in the Y-axis direction.

sln (-1 θ) = n sin (L-θ+α)
...■, π 2 If this ray hits the +0 plane, the ray will return to the original state and exit as a ray parallel to the X-axis. In this way, it is incident on the +0 plane and +0
The light rays emitted from the plane, or similarly, the light rays 5 that enter the −0 plane and exit from the 1θ plane are L tanα, −
The light is emitted with a deviation in parallel by Ltanα. Here, θ is calculated using the formula 0. If it is taken to be equal to , then α=−〇, and all light parallel to the X axis will pass through either of the two optical paths mentioned above.

Furthermore, the light that reaches the side surface 6 before reaching the output surface 22 has an incident angle of π/2-θ. From equation 0, π n5xn (--θ,)=ncosθ0(,'n>1
) holds true, so if the side surface 6 is not in optical contact with any other substance and faces an air layer, it will be totally reflected and reach the output surface. Furthermore, if the side surface 6 is made into a reflective surface by metal vapor deposition or the like, the same result will be obtained even if this surface is in contact with another substance.

The double-serrated transparent plate 1 divides a light beam incident perpendicularly onto an incident surface 20 into light beams whose optical axis is bent by angles α and −α at the incident surface 20, and then divides the beam into beams whose optical axis is bent by angles α and −α at the incident surface 20, and then divides the beam into beams whose optical axis is bent by angles α and −α at the incident surface 20, and then divides the beam into two beams whose optical axis is bent by angles α and −α at the incident surface 20, and then divides the beam into beams whose optical axis is bent by angles α and −α at the incident surface 20, and then divides the beam into two beams whose optical axis is bent by angles α and −α at the incident surface 20, and then divides the beam into beams whose optical axis is bent by angles α and −α at the incident surface 20, and then divides the beam into beams whose optical axis is bent by angles α and −α at the incident surface 20. By returning the light flux to parallel to the axis of
This provides the same effect as when two light sources with a light intensity of .

In FIG. 1, this effect is not affected by the period T (also called the prism pitch) of each prism unit 30 formed on the incident surface 20 and exit surface 22 of the light beam, and the prism units 30 are aligned with the X axis. This can be achieved as long as the angle θ is formed accurately. For example, as shown in FIG. 11, a structure in which the period T1 of the prism units 30 on the side of the entrance surface 20 is twice as long as the period T2 on the side of the exit surface 22 can be adopted.

In addition, as shown in FIG. 12, the entrance surface 2o and the exit surface 22
The deviation dy of each prism unit 30 in the Y-axis direction does not pose a problem due to the above-mentioned effects, and positioning accuracy between the entrance surface 20 and the exit surface 22 is not required for manufacturing purposes.

Next, FIGS. 2(a) and 2(b) are a plan view and a perspective view, respectively, of a transparent plate 7 used in the present invention. It is a rectangular transparent plate with a distance between surfaces 22.

Figure 3 shows a transparent plate l and a transparent plate 7 arranged alternately at a height H.
This is an optical component 17 according to the present invention, which is laminated up to . The thickness of the transparent plate 1 is d l %, and the thickness of the transparent plate 7 is d.

FIG. 4 shows a laminated state according to the first aspect of the present invention, in which a low refractive index layer 8 is interposed between the transparent plate 1 and the transparent plate 7 which have a brim tooth shape.

The low refractive index layer 8 may be a low refractive index adhesive or a low refractive index film. Moreover, it is sufficient to simply leave a space between them, and in this case, it is sufficient to simply laminate the transparent plates 1 and 7 in the form of both flanges so that there is no optical adhesion between them. Due to the presence of the low refractive index layer 8, the transparent plate 1. Each of the transparent plates 7 functions as an independent light guide for light rays that enter at a small angle with respect to the normal to the incident surface. Since the present invention is based on the assumption that the incident light is a beam-like light beam,
This can be easily achieved by setting a sufficiently large difference in the refractive index between the low refractive index layer 8 and the transparent plates 1 and 7 having a double brim tooth shape.

Furthermore, in the second term, a metal reflective surface is provided between the transparent plate 1 and the transparent plate 7 (thereby, each transparent plate is given independence as a light guide).

Here, if the incident light that enters the incident surface has the light amount distribution shown in FIG. 1+
Light rays incident on the 0 surface and emitted from the +0 surface), light intensity distribution 11
(Light ray that enters the -θ plane and exits from the 1θ plane), light intensity distribution 10° (ray that enters the +0 plane, reflects at surface 6, and then exits from the -θ plane), light intensity distribution 11゛ (ray that enters the -θ plane This is a combination of light rays that are incident, reflected by the surface 6, and then emitted from the rear θ plane. The above-mentioned double-flange-shaped transparent plate 1. Due to the independence of the transparent plate 7, there are no light rays that enter the double-flange-shaped transparent plate l and exit from the transparent plate 7, or light rays that enter the transparent plate and exit from the double-flange-shaped transparent plate 1. . Here, if the thickness d of the double-flange-shaped transparent plate 1 is twice the thickness d2 of the transparent body 7, the light intensities of the light intensity distributions 9, 10° 11 will be approximately equal, and the output light will have the same amount of light. The distribution is made uniform as shown in 12. It is also clear that the parallelism of the incident light is not impaired.

In the third aspect of the present invention, as shown in FIG. 1O, the transparent plate 7 is omitted,
Instead, a gap 40 is provided, which has the same effect as above. At this time, if the surface of the transparent plate 1 in the shape of both flanges that is in contact with the gap 40 is used as a reflective surface, the gap 40 becomes a complete light guiding path, and its effect is almost the same as that of the transparent plate 7 in the second term. no change. Even when a reflective surface is not formed, the reflectance for light incident at an angle close to parallel to the surface is relatively large, so it can be regarded as an approximate light guide, and the effect is similar to the second term, although the loss increases slightly. is obtained.

As can be seen from Fig. 6, in order to obtain a luminous flux with the width of the exit surface, dl = d* X2 and L tan α =
Just choose L so that it becomes W/3.

i.e. If (, θ=θ, then becomes.

If the incident light is perfectly parallel light, the light intensity distribution will have light intensity irregularities with the period T of the prism in the Y direction, and dl + da + in two directions.
It has light intensity irregularities with a period of ds. Since the present invention realizes uniformity of a light beam having a slight spread angle, it is actually possible to eliminate unevenness in the amount of light with period T by using light at a predetermined distance from the exit surface. If the distance is set as D, then δ represents the smaller of the spread angle of the incident light flux or the spread angle available to the device that uses the output light flux. Therefore, if T is small, D is It can be made small, which is preferable for downsizing the device, but if it is made too small, the roundness of the corners of the serrated surface will be affected by the limit of processing accuracy, so it is not preferable to make it too small.

Also, the fact that the spread angle δ is not O means that the value of the refraction angle α has a corresponding spread, so θ=θ. Even so, there are light ray components as shown in FIGS. 7, 13 to 15, and strictly speaking, it is not as shown in FIG. 6, but θ→θ. In this case, the effect shown in FIG. 6 can be obtained if the spread angle δ is not too large. The equalization component of the present invention works effectively (in order for δ
It is necessary that Since the light beams take optical paths such as 13 to 15 in the figure, they are hardly effective light rays.

Next, a method for determining the valid range of the value of θ will be explained.

In FIG. 13, if it is assumed that a light beam with a spread angle δ at the incident plane has a spread angle δ° when it enters a medium with a refractive index n, then δ° can be expressed in the first approximation as follows.

5in(x/2-ψ) = n 5in(π/2-φ
),, COSψ= n cosφ ,', sinψdψ=n sinφdφ ,', dφ= (sinψ/n5inφ)dψδ' =
(sinψ/n5inφ)δ At this time, the angle ψ is θ. If it is equal to , then φ = 2ψ = 20°, so dφ = dψ / 2ncosψ -○ δ1 = δ / 2ncosψ ... 6 Next, consider when the angle ψ is increased by Δψ as shown in Figure 14. . The angle of bending of parallel light φ° is given by 0 equation % equation %) If Δψ is small, the spread angle within the medium is approximately equal to δ゛ of 0 equation. If δ° is larger than the second term on the right side of 0 equation,
There is a ray component that satisfies φ゛=2(ψ+Δψ)...0 within the spread angle. Since this component is the component that exhibits the effects of the present invention most efficiently, having this component is a condition for applying the present invention.

Therefore, δ'> (2-1/2 n cos ψ) Δψ,, Δψ × δ
/(4n cos ψ-1) , °, Δθ × δ/(4 n cos θ.-1) 3. Δθ〈δ
/ (1+8 n”) ”” -O From this, the formula is derived.

This inference was made regarding the spread angle of the incident light, but if δ is the effective spread angle of the output light, exactly the same result will be obtained by tracking the line of sight at the exit surface.

As can be seen from FIG. 6, the features of the optical component of the present invention are as follows:
Of the light beam incident perpendicularly to the incident surface, a portion passes through the transparent plate 7 (in the third term, the gap between the two adjacent sawtooth transparent plates 1), and the rest is incident on the both sawtooth transparent plates l. By dividing the optical axis into light beams bent by angles α and −α at the surface and returning the light beam parallel to the original axis at the exit surface at a certain distance, it is similar to three light sources lined up. It is effective.

This homogenizes the luminous flux, but it also has the effect of expanding the luminous flux.

Here, the ratio of dl and d2 determines the intensity ratio of the central light source and the left and right light sources, and if you want equal intensities as shown in Figure 6, set a l/ az = 2 (and , α determine the position of the light source divided into left and right sides, and if a uniform luminous flux is required across the width of the component as shown in Figure 6, it can be determined from equation 0.Also, the required width of the luminous flux is determined by the width of the component. If it is smaller than the width W, L tanα may be made smaller or a l/am may be adjusted accordingly.

The optical component according to the present invention has the effect of uniformizing the amount of light only in the Y-axis direction, but when using a light source 16a in which the unevenness of the amount of light is limited to one direction as shown in FIG. A device using one optical component 17 may be sufficient, but if the light source 16b has a two-dimensional non-uniform light amount, the optical component 17 can be arranged in two stages with the Y-axis perpendicular to each other as shown in FIG. 9 to make the amount of light uniform. It is necessary to measure it.

Note that in the optical component according to the present invention, a portion of the light ray is reflected when the light ray enters and when the light ray exits, and the amount of transmitted light is reduced. This reflectance is around n=1.5, lO%
It will be about. To reduce this loss and increase efficiency, an anti-reflection coating can be applied. It is also effective to lower the 1 reflectance by thinly coating the material with a low refractive index material.

[Effects of the Invention] As explained above, the optical component according to the present invention uniformizes the light intensity of a non-uniform light beam created by using a reflective curved surface or a lens as a light source without impairing its beam properties. This makes it possible to easily produce a light source that provides a highly efficient and uniform luminous flux, and has a great practical effect.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a plan view and a perspective view, respectively, of a double-flange-shaped transparent plate 1. FIG. Figure 2 (a), (b)
These are a plan view and a perspective view, respectively, of a transparent plate 7 used in the present invention. FIG. 3 is a diagram showing the optical component of the first aspect of the present invention (the second aspect also has a similar shape), and FIG. 4 is a diagram showing a laminated state of the transparent plate 1 and the transparent plate 7, which have a double brim tooth shape. . FIG. 5 is a diagram showing the distribution of the amount of incident light, and FIG. 6 is a diagram for explaining the principle by which the amount of light is made uniform. FIG. 7 is a diagram showing that because the incident light beam has a divergence angle, there are light rays that take different paths from the light rays shown in FIG. 1. Fig. 8 is a configuration diagram when the present invention is applied to incident light having non-uniformity in light amount in only one direction, and Fig. 9 shows how to use the present invention when applied to incident light having non-uniformity in two dimensions. It is a diagram. FIG. 10 is a diagram showing an optical component according to the third aspect of the present invention. FIG. 11 and FIG. 12 are diagrams showing the deformation of the double-flange-shaped transparent plate l, respectively, and FIGS. 13 and 14 are diagrams, respectively, for explaining the basis for deriving ■. l...Transparent plate 2 with double brim tooth shape...-0 surface 3...+0 surface 6...Side surface 7...Transparent plate 8...Low refractive index layer 16a, 16b-Light source 17. ...Optical component of the present invention

Claims (3)

[Claims] (1) A biserrated transparent plate 1 that satisfies the following condition A and has a plurality of prism units formed on a pair of opposite sides, and a rectangular transparent plate 7 whose sides are the same length as the transparent plate 1. ,
An optical component for uniformizing light flux, characterized in that layers 8 having a lower refractive index than those of the transparent plates 1 and 7 are alternately laminated with layers 8 formed therebetween. (Condition A) When the Y-axis is parallel to the side on which multiple prism units are formed, the X-axis is parallel to the side perpendicular to this, and the Z-axis is in the plate thickness direction,
The prism unit forms an angle θ to −θ with the X axis as expressed by the formula {1}{2}. θ_0-δ/(1+8n^2)^1^/^2<θ<θ_
0+δ/(1+8n^2)^1^/^2...{1}θ
＿0=COS＾−＾1；[1+(1+8n＾2)＾1＾
/^2]/4n}...{2} However, δ is the smaller of the spread angle of the incident light flux or the spread angle (±δ) that can be used by the device that uses the output light flux, and δ<θ n: Refractive index of transparent plate 1 (2) A feature in that the double-serrated transparent plates 1 according to claim 1 and rectangular transparent plates 7 whose sides are equal in length to the transparent plates 1 are alternately laminated with metal reflective surfaces in between. An optical component that equalizes the luminous flux. (3) An optical component that homogenizes a light beam, which is obtained by removing the rectangular transparent plate 7 from the double sawtooth transparent plate 1 according to claim 1, and stacking the low refractive index layers in parallel with an interval. .