JP5363884B2 - Light emitting device and optical element - Google Patents

Description

  The present invention relates to a light emitting device and an optical element.

  The following has been proposed as an illumination device using an LED (Light Emitting Diode) as a light source. That is, one end surface is an incident end surface and the front surface is formed in a stepped surface, and a reflector is provided behind the light guide plate that guides light incident from the incident end surface and exits from a plurality of step surfaces on the front surface. A light emitting element is arranged to face the incident end face of the optical plate. And the diffusion means which absorbs a part of light is provided in the front side of the edge part area | region of the range more than the height of an incident end surface from the incident end surface of a light-guide plate. Further, the illumination device has an optical member that refracts light emitted from a plurality of step surfaces of the light guide plate in a direction in which an angle with respect to the step surface is reduced, facing a portion other than the end region on the front side of the light guide plate. (Refer to Patent Document 1).

  In this illuminating device, when the light incident on the light guide plate from the incident end face is emitted from the vicinity of the end on the incident end face side, the light is diffused by the diffusing means and proceeds to the center side. And this illuminating device makes the area | region corresponding to parts other than the edge part area | region of the incident end surface side of a light-guide plate the light emission area, and it is made to radiate | emit the light of uniform intensity distribution from the whole area of this emission area. .

JP 2004-119143 A

  However, since the illumination device described in Patent Document 1 uses a light emission area other than the portion where the diffusing means is provided, the light guide plate is considerably longer than the illumination area. As a result, the lighting device tends to be enlarged.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting device and an optical element that can be miniaturized while uniformly emitting light from a light guide.

In order to achieve the above object, a light-emitting device of the present invention includes a rod-shaped light guide unit, a light source that makes light incident on the light guide unit, and light that is incident from the end in the longitudinal direction of the light guide unit. Light that exits and contains light scattering particles that scatter the emitted light and guide most of the incident light to the same direction side as the incident direction. light scattering guide to emit from the emission surface of many provided et al is the exit surface of light guide portion and the light scattering guide has a concave recessed planar or from short opposite end of the light guide, toward the center Suppose that
In addition, the light emitting device of the present invention emits light incident from the longitudinal end portion of the light guide portion from the light exit surface, and guides the light from the rod-shaped light guide portion, the light source that makes light incident on the light guide portion, and the light guide. The long side end portion of the unit contains light scattering particles that multiple-scatter the emitted light and guide most of the incident light to the same direction side as the incident direction. The light-scattering light-guiding unit that is emitted from the light-guiding unit is provided, and the light-guiding unit and the light-scattering light-guiding unit have emission surfaces that are convex surfaces that bulge from both ends of the light-guiding unit toward the center.

Here, the light source further includes a direction changing unit that changes the direction of light incident from the end in the long direction so as to face the output surface, and the light source is a side or direction changing unit that approaches the direction changing unit from the central axis of the light guide unit. It is preferable that the light incident on the light guide portion is directed toward the light exit surface or the direction changing portion of the light guide portion by shifting to the side away from the light guide portion.
Moreover, it is preferable to provide the mirror surface member which has the reflective surface of the paraboloid which reflects the light radiate | emitted from the light source to the light guide part side in the elongate direction edge part side of a light guide.

In order to achieve the above object, an optical element of the present invention has a rod-shaped light guide part and a direction changing part that changes the direction of light incident from the longitudinal end of the light guide part. The light whose direction is changed by the direction changing unit is emitted from the emission surface arranged so as to be opposed to the light source, and the emitted light is subjected to multiple scattering on the longitudinal direction end portion side of the light guide unit in the emission surface, and containing light scattering particles leading to many has entered the light in the same direction as the incident direction, the light scattering guide to emit from the emission surface more light that has been incident Re et provided as a part of the light guide portion The light exit surface of the light guide and the light scattering light guide is a flat surface or a concave surface that is recessed from both ends in the short direction of the light guide toward the center.
In addition, the light emitting device of the present invention has a rod-shaped light guide unit and a direction changing unit that changes the direction of light incident from the longitudinal end of the light guide unit, and faces the direction changing unit. The light redirected by the direction changer is emitted from the arranged exit surface, and the emitted light is subjected to multiple scattering and incident on the end of the light guide in the longitudinal direction of the exit surface. A light scattering light guide that contains light scattering particles that guide most of the incident light in the same direction as the incident direction and that emits most of the incident light from the exit surface is provided as part of the light guide. The exit surface of the scattering light guide is a convex surface that bulges from both ends in the short direction of the light guide toward the center.

  Here, a part other than the light-scattering light-guiding unit in the light-guiding unit is a transparent body, or the transparent body includes light-scattering particles at a lower content than the light-scattering light-guiding unit. can do.

  Moreover, the convex lens-shaped incident lens is arrange | positioned at the both ends surface of the elongate direction of a light guide part so that it may swell from an elongate direction edge part, and an end surface other than the part by which an incident lens is arrange | positioned It is preferable that it is provided so that it may extend in the elongate direction of a light guide part.

  The light scattering light guides are provided at both ends of the light guide, respectively, and the direction changing part is a prism having a triangular cross section, which is an angle of the reflection surface with respect to a line connecting the apexes of the prisms, and has one length. When the angle of the reflecting surface that reflects the light incident from the end in the lengthwise direction is A, and the angle of the reflecting surface that reflects the light incident from the other end in the lengthwise direction is B, the one long direction It is preferable that A <B in the end region, A> B in the other end region in the longitudinal direction, and A = B in the central region in the longitudinal direction of the light guide unit.

  In addition, the light scattering particles contained in the light scattering light guide are turbidity, which is a scattering parameter corresponding to the scattering coefficient, τ, and the length in the central axis direction of each light scattering light guide is α / 2. In this case, it is preferable that the average scattering number value indicating the average scattering number is in the range of 5 <α / (2 × τ) <50.

  In addition, the light guide part other than the light scattering light guide part also includes light scattering particles, and the light scattering particles contained in the part other than the light scattering light guide part have a scattering parameter corresponding to the scattering coefficient. When the turbidity is τ and the length of the light guide in the axial direction is L, the average number of scattering times indicating the average number of scattering is within the range of 0 <L / τ <60, and the light scattering guide It is preferable that the average number of scattering times of the light part is larger than the value of the light guide part other than the light scattering light guide part.

  Moreover, it is preferable that the value of turbidity, which is a scattering parameter corresponding to the scattering coefficient of the light scattering light guide, is made larger than the value of the light guide other than the light scattering light guide.

  Further, when the total length of the light scattering light guide in the axial direction is α and the length of the light guide in the axial direction is L, L / 15 <α <L / 2. Is preferred.

  The thickness t of the light-scattering light guide in the direction perpendicular to the exit surface at the center in the short direction of the light guide is T / 20 <, where T is the thickness of the light guide in the direction perpendicular to the exit surface. It is preferable that t <T / 2.

  In order to achieve the above object, a light-emitting device of the present invention includes any one of the optical elements described above and light sources disposed at both ends or one end of the optical element.

  Here, it is preferable that the light source is an LED, and the LED is disposed at a position closer to the surface opposite to the exit surface from the center of the longitudinal end of the optical element.

  According to the present invention, it is possible to provide a light emitting device and an optical element that can be miniaturized while uniformly emitting light from the light guide.

It is a front view which shows the structure of the light guide which is an optical element which concerns on the 1st Embodiment of this invention. It is a right view of the light guide shown in FIG. It is a figure which shows the scattering principle of the silicone particle used as the light-scattering particle | grains in the light-scattering light guide part which comprises the light guide shown in FIG.1 and FIG.2, and is an angle distribution (Α, It is a graph which shows (Θ). It is a schematic diagram which shows the side surface shape of the prism part which exists in about half length from the elongate direction edge part of the light guide which concerns on embodiment of this invention, and also when LED is turned on, It is also a schematic diagram which shows the light incident / exit situation of the light emitting device according to the embodiment. It is a longitudinal cross-sectional view of the light-emitting device of 1st Embodiment. FIG. 6 is a diagram showing the distribution of brightness (light quantity) of the light emitting device as a simulation result with the horizontal axis representing the distance from the center of the light guide of the light emitting device shown in FIG. 5 and the vertical axis representing the illuminance of light from the exit surface. is there. The brightness distribution of the light emitting device of the comparative example having the same configuration as the light emitting device shown in FIG. 5 is the same as that of FIG. 6 except that the light scattering light guide portion is made transparent like the other light guide portions. FIG. It is a figure which shows the brightness | luminance chart of the output surface when light-emitting device which concerns on embodiment of this invention is light-emitted, Comprising: It is a figure where a brightness | luminance becomes low, so that it approaches white and a brightness | luminance becomes high. It is a figure which shows the brightness | luminance chart of the output surface when making the light-emitting device of the comparative example shown in FIG. 7 light-emit, and is a figure where a brightness | luminance becomes low, so that it approaches white and a brightness | luminance becomes high. It is a figure which shows distribution of brightness similarly to FIG. 6 about the light-emitting device which concerns on the 2nd Embodiment of this invention. FIG. 6 is a schematic diagram showing a cross section of a light emitting device according to a third embodiment of the present invention, similar to FIG. 5, and also shows an enlarged view of a prism portion at both ends in the longitudinal direction and a central portion in the longitudinal direction. FIG. It is a figure which shows the emission direction of the light of the illuminating device of the 1st Embodiment of this invention, and the illuminating device of the 3rd Embodiment of this invention. It is a side view equivalent to FIG. 2 of the light-emitting device of the 1st modification of the light-emitting device which concerns on embodiment of this invention. It is a side view equivalent to FIG. 2 of the light-emitting device of the 2nd modification of the light-emitting device which concerns on embodiment of this invention. The figure on the left side is a side view showing the configuration of the light guide according to the embodiment of the present invention, the figure corresponding to FIG. 2 in the light guide according to the first embodiment, the figure on the right side is It is a front view which shows the structure of the edge part of the light guide shown to the left figure, and is a figure equivalent to a part of FIG. 1 in the light guide which concerns on 1st Embodiment.

  Hereinafter, the configuration of the optical element and the light emitting device according to the embodiment of the present invention and the operation thereof will be described with reference to the drawings.

(Configuration of Optical Element of First Embodiment)
FIG. 1 is a front view showing a configuration of a light guide 1 which is an optical element according to a first embodiment of the present invention, and FIG. 2 is a side view thereof.

  As shown in FIG. 1 and FIG. 2, the light guide 1 is mainly composed of a rod-shaped light guide unit whose outer shape is close to a long rectangular column. The light guide 1 is provided at both ends in the longitudinal direction of the light guide unit, and is formed on the lower surface of the light guide unit. Are formed on the upper surface of the light guide unit, the two light-scattering light guide units 5 and 5 that are disposed at both ends in the longitudinal direction of the upper surface of the light guide unit and are part of the light guide 1. It has a light exit surface 6 that becomes part of the light guide 1 and emits light incident from the end in the longitudinal direction of the light guide 1.

  A portion of the light guide 1 other than the light scattering light guide 5 is a resin molded body made of transparent polymethylmethacrylate (hereinafter abbreviated as “PMMA”), and has a substantially quadrangular prism shape. . The incident lens 3 is also a convex lens made of PMMA and having a hyperbolic cross section. The light guide 1 and the incident lens 3 are integrally formed.

  As shown in FIG. 2, the end surface in the longitudinal direction of the light guide 1 is a flat flat surface 7, and the incident lens 3, which is a convex lens bulging from the end in the longitudinal direction, is disposed at the center. And the light-scattering light guide part 5 is provided so that it may extend in the elongate direction of the light guide 1 from the flat surfaces 7 other than the part by which the incident lens 3 is arrange | positioned. In FIG. 1 and FIG. 2, illustration of the detailed form of the prism part 4 used as a direction change part is abbreviate | omitted, and description about the detailed shape of the prism part 4 is mentioned later.

  The light scattering light guide 5 is a PMMA resin molded body containing spherical and translucent silicone particles (not shown) having a particle diameter of 2 μm to 9 μm as light scattering particles. The lengths of the two light scattering light guides 5 are the same dimension α / 2 (unit is cm), and the sum α of the length dimensions α / 2 of the two light scattering light guides 5 is the light guide. 1/10 of the dimension L in the longitudinal direction (unit: cm). The two light-scattering light guides 5 have the same dimension W1 in the short direction as the dimension W2 in the short direction of the light guide 1. The thickness dimension t (unit: cm) of the light-scattering light guide in the direction perpendicular to the exit surface 6 at the center in the short direction of the light guide 1 is the thickness T of the light guide 1 in the direction perpendicular to the exit surface 6. When the unit is cm, t = T / 5. As shown in FIG. 2, the upper surface of the light scattering light guide 5 swells from both ends in the short direction toward the center. The shape of this bulge is the shape of a part of the side surface of the cylinder. That is, the surface is a part of a spherical surface. In the light guide 1, the part other than the light scattering light guide 5 and the light scattering light guide 5 are integrated by two-material molding.

  Here, the light scattering particles contained in the light scattering light guide 5 have an average number of scattering times when turbidity, which is a scattering parameter corresponding to the scattering coefficient of the light scattering light guide 5, is τ (unit: cm). The average number of times of scattering representing the above is within a range of 5 <α / (2 × τ) <50 with respect to each length α / 2 of the light scattering light guide 5 described above. The total length α in the axial direction of the light-scattering light guide 5 is determined by taking the length of the light guide 1 in the axial direction from L to L in consideration of the uniformity of the entire emitted light. / 30 <α <L / 4. Furthermore, the thickness t of the light scattering light guide 5 described above is T / 20 <t <T with respect to the thickness T of the light guide 1 in consideration of efficiently guiding incident light to the exit surface 6. Within the range of / 2.

  Hereinafter, the silicone particles of the light scattering light guide 5 will be described. This silicone particle is a light guide provided with a volumetric uniform scattering ability, and includes a large number of spherical particles as scattering fine particles. When light enters the light scattering light guide 5, the light is scattered by the scattering fine particles.

  Here, the Mie scattering theory that gives the theoretical basis of the silicone particles will be described. Mie scattering theory is the solution of Maxwell's electromagnetic equation for the case where spherical particles (scattering fine particles) having a refractive index different from that of the medium exist in a medium (matrix) having a uniform refractive index. . The intensity distribution I (Α, Θ) depending on the angle of the scattered light scattered by the scattering fine particles corresponding to the light scattering particles is expressed by the following equation (1). Α is a size parameter indicating the optical size of the scattering fine particles, and is an amount corresponding to the radius r of the spherical particles (scattering fine particles) normalized by the wavelength λ of light in the matrix. The angle Θ is a scattering angle, and the same direction as the traveling direction of incident light is Θ = 180 °.

Further, i ₁ and i ₂ in the formula (1) are represented by the formula (4). And a and b with subscript ν in the expressions (2) to (4) are expressed by the expression (5). P (cos Θ) with superscript 1 and subscript ν is Legendre's polynomial, a and b with subscript ν are first-order and second-order Recati-Bessel functions Ψ _* , ζ _* (where “*” Means the subscript ν) and its derivative. m is the relative refractive index of the scattering fine particles based on the matrix, and m = nscatter / nmattrix.

  FIG. 3 is a graph showing the intensity distribution I (Α, Θ) by a single true spherical particle based on the above equations (1) to (5). FIG. 3 shows an angular distribution I (Α, Θ) of scattered light intensity when there is a true spherical particle as a scattering fine particle at the position of the origin G and incident light is incident from below. And the distance from the origin G to each curve S1-S3 is the scattered light intensity | strength of each scattering angle direction. Curve S1 shows the scattered light intensity when Α is 1.7, curve S2 shows the scattered light intensity when Α is 11.5, and curve S3 shows the scattered light intensity when Α is 69.2. Yes. In FIG. 3, the scattered light intensity is shown on a logarithmic scale. For this reason, the portion that appears as a slight difference in intensity in FIG. 3 is actually a very large difference.

  As shown in FIG. 3, the larger the size parameter Α (the larger the particle size of the true spherical particle when considered at a certain wavelength λ), the higher the directivity with respect to the upper side (front of the irradiation direction). It can be seen that light is highly scattered. Actually, the angle distribution I (Α, Θ) of the scattered light intensity is controlled by using the radius r of the scatterer and the relative refractive index m of the medium and the scattered fine particles as parameters if the incident light wavelength λ is fixed. can do. The light scattering light guide 5 has a large forward scattering.

  When light is incident on such a light scattering light guide containing N single spherical particles, the light is scattered by the spherical particles. Scattered light travels through the light scattering light guide and is again scattered by other spherical particles. When particles are added at a volume concentration of a certain level or more, such scattering is sequentially performed a plurality of times, and then light is emitted from the light scattering light guide. A phenomenon in which such scattered light is further scattered is called a multiple scattering phenomenon. In such multiple scattering, analysis by a ray tracing method with a transparent polymer is not easy. However, the behavior of light can be traced by the Monte Carlo method and its characteristics can be analyzed. According to this, when the incident light is non-polarized light, the cumulative distribution function F (Θ) of the scattering angle is expressed by the following equation (6).

  Here, I (Θ) in the equation (6) is the scattering intensity of the true spherical particle having the size parameter 表 represented by the equation (1). Assuming that light having an intensity Io is incident on the light-scattering light guide and transmitted through the distance y, the intensity of the light is attenuated to I due to scattering, and these relationships are expressed by the following equation (7).

  Τ in the equation (7) is called turbidity and corresponds to the scattering coefficient of the medium, and is proportional to the number N of particles as in the following equation (8). In the equation (8), σs is a scattering cross section.

  From the equation (7), the probability Pt (L) of transmitting the light scattering light guide having a length L without scattering is expressed by the following equation (9).

On the other hand, the probability Ps (L) scattered up to the optical path length L is expressed by the following equation (10).

  As can be seen from these equations, the degree of multiple scattering in the light scattering light guide can be controlled by changing the turbidity τ.

  By the above relational expression, it is possible to control multiple scattering in the light scattering light guide using at least one of the size parameter Α and turbidity τ of the scattering fine particles as a parameter, and the outgoing light intensity and scattering angle on the outgoing surface 6 can be controlled. Can also be set appropriately.

  FIG. 4 is a schematic diagram showing a side shape of the prism portion 4 existing about half the length from the longitudinal end portion of the light guide 1. A plurality of convex portions 10 having a triangular cross section are formed in the same shape on the surface facing the emission surface 6 that is the upper surface of the light guide 1, that is, the lower surface of the light guide 1 at equal intervals. Further, a sawtooth-shaped concave portion 11 is formed by the adjacent convex portions 10. The apex of the sawtooth is the most protruding portion of the recess 10. The convex portion 10 and the concave portion 11 constitute the prism portion 4. The convex portion 10 and the concave portion 11 are formed at the same time when the light guide 1 and the incident lens 3 are integrally formed by a mold. Further, a reflection film is attached to the surface of the prism portion 4 (the lower surface in FIG. 4), and reflects the light that travels through the light guide portion and strikes the prism portion 4.

(Configuration of Light Emitting Device of First Embodiment)
FIG. 5 is a longitudinal sectional view of the light emitting device 20 of the first embodiment using the light guide 1. At both ends of the light guide 1, an LED 21 as a light source and a mirror member 22 as a reflecting member are fixedly arranged. The LED 21 is of a chip type. The LED 21 is disposed closer to the prism portion 4 than the optical axis M1 of the incident lens 3 (lower side in FIG. 5). That is, the LED 21 is shifted downward with respect to the optical axis M1. As a result of this shift, the arrangement position of the LED 21 is an intermediate position between the optical axis M1 and the prism portion 4. Here, the optical axis M <b> 1 of the incident lens 3 is a line that is parallel to the prism portion 4, is also parallel to the exit surface 6, and passes through the center of the incident lens 3.

  Each mirror member 22 has a cup-like shape in which the longitudinal section in FIG. 5 draws a parabolic curve. This parabola is the same when cut by any cross section including the optical axis M1. The focal position of the parabola is set to be on the optical axis M1. The inner surface of the cup-shaped mirror member 22 is mirror-finished so that the light from the LED 21 can be reflected. Further, the opening end portion of the cup-shaped mirror surface member 22 covers the end portion of the light guide 1, and the LED 21 is glazed so that the light from the LED 21 does not leak between the mirror surface member 22 and the light guide body 1. For this reason, most of the light from the LEDs 21 placed at both ends of the light guide 1 is incident on the light guide 1.

(Status of light incident / exit of the light emitting device 20 when the LED 21 is turned on)
FIG. 4 is also a schematic diagram showing the light incident / exit status of the light emitting device 20 when the LED 21 is turned on. In FIG. 4, an optical path of light that is directly incident on the incident lens 3 from the LED 21 (shown by a broken line) and an optical path of light that is incident on the incident lens 3 after the light from the LED 21 is reflected by the mirror member 22. (Shown by a solid line).

  The LED 21 is located at the center of the LED 21 slightly below the both focal positions F, which is the focal position of the incident lens 3 and the focal position of the parabola of the mirror member 22 (= downward in the direction perpendicular to the optical axis M1). Placed in. The center position of the LED 21 may be other lower positions that are lower positions of the optical axis M1 such as obliquely lower than the lower positions in the vertical direction from both focal positions F. In FIG. 4, for the sake of easy understanding, the center of the LED 21 is shown at a position considerably away from both focal positions F. The light emitted from the LED 21 is light whose emission range is considerably limited as compared with a light bulb or the like, but part of it is divergent light having an angle. However, after the light having such an angle also enters the incident lens 3, it approaches the parallel light due to the convex lens action. And the light which injects into the incident lens 3 from LED21 is once irradiated to the output surface 6 (it becomes an upper side surface) of the light guide 1 in FIG. And the light whose incident angle becomes more than a critical angle increases, is totally reflected by the output surface 6 and goes to the prism part 4 side. Light directed to the prism unit 4 is redirected by the prism unit 4. The direction change in the prism portion 4 is substantially perpendicular to the emission surface 6, and the light from the prism portion 4 is emitted through the emission surface 6. Here, a part of the light that is directly incident on the incident lens 3 by the light emitted from the LED 21 enters the light scattering light guides 5 at both ends in the length direction of the emission surface 6. A part passes through while being scattered and exits.

  A part of the light that is incident on the incident lens 3 after the light from the LED 21 is reflected by the mirror surface member 22 also has a light that takes an optical path that is redirected by the prism portion 4 through total reflection at the exit surface 6. . However, the other part of the light reflected by the mirror member 22 and incident on the incident lens 3 does not undergo total reflection at the exit surface 6 as shown in FIG. The light is incident on the light scattering light guide unit 5 or directly irradiated on the prism unit 4. A part of the light that immediately enters the light scattering light guide 5 passes through the exit surface 6 while being scattered, and the other part is reflected by the exit surface 6. The light whose direction has been changed by the prism unit 4 is scattered through the light scattering light guide unit 5, a part of which is emitted through the exit surface 6, and the other part is reflected by the exit surface 6.

  FIG. 6 is a diagram illustrating the distribution of brightness (light quantity) of the light guide 1 as a simulation result with the distance from the central portion of the light guide 1 as the horizontal axis. The simulation condition is that the light emitting surface of the LED 21 is 1 mm square, the brightness is 150 lumens / piece, the spread angle is 160 °, and the brightness at a position 10 mm away from the exit surface 6 in the light scattering light guide 5 is displayed. (The same applies to the one shown in FIG. 7). Note that the vertical axis is Lux. The upper surfaces of the light-scattering light guide 5 and other light guides shown in FIG. 2 bulge from both ends in the short direction of the light guide 1 toward the center, and thus serve as a convex lens. Therefore, the light emitted from the emission surface 6 gathers at a position away from the emission surface 6 by a predetermined distance, and when a sheet (for example, a scanner sheet) is placed at that position, a line parallel to the optical axis M1 is placed on the sheet. -Shaped illumination lines are projected. Moreover, since the light-scattering light guide part 5 of the both ends of the light guide 1 contains light-scattering particle | grains, the emitted light radiate | emitted there is scattered a little. As a result, the light emitted from the light scattering light guide 5 has a width corresponding to the short direction of the light guide 1 wider than the light from the other light guides. Furthermore, as shown in FIG. 6, the amount of light emitted from the central portion is smaller than that from both end portions of the light guide 1. This is because the installation of the light scattering light guide unit 5 increases the guidance of the incident light to the center side, but the light emitted from the both ends of the light guide 1 is very close to the LED 21. This is because the optical path is shortened and the intensity thereof is increased.

  FIG. 7 corresponds to the light guide 1 with respect to the light emitting device of the comparative example having the same configuration as the light emitting device 20 except that the light scattering light guide portion 5 is made transparent like the other light guide 1 portions. It is a figure which shows distribution of the brightness of a part similarly to FIG. FIG. 8 is a diagram illustrating a luminance chart of the emission surface 6 when the light emitting device 20 emits light. In FIG. 8, the luminance decreases as it approaches black, and the luminance increases as it approaches white. FIG. 9 is a diagram showing a luminance chart of the exit surface 6 when the light emitting device of the comparative example shown in FIG. 7 is caused to emit light. The luminance becomes lower as it gets closer to black, and the luminance becomes higher as it gets closer to white.

  Comparing FIG. 6 with FIG. 7, it can be seen that in the light emitting device 20, the intensity of light emitted from both ends of the light guide 1 is suppressed by the light scattering action of the light scattering light guide 5. . The amount of the suppressed light is widened in the short and long directions of the light guide 1 at both ends in the long direction of the light guide 1 (see FIG. 8). In addition, the two end portions of the light guide 1 have two extremely bright portions, and the portion between them (the portion where the horizontal axis is about +140 mm and about −140 mm) is dark. The light emitting device 20 leveles the brightness of the entire light guide 1 by slightly increasing the darkness of the portion between them. That is, as can be seen from a comparison with the 100,000 lux line in FIG. 6 and FIG. 7, the light scattering guide 5 in FIG. It is brighter than those without the scattering light guide 5. Further, as can be seen from the comparison between FIG. 8 and FIG. 9, the light portion in the short direction at the center of the light guide 1 is wider when the light scattering light guide 5 is installed.

  Therefore, the light guide 1 is not particularly dazzled at both end portions in the longitudinal direction, and the light guide 1 can be irradiated with light of substantially uniform intensity over the entire light guide 1. More specifically, the ratio (H2 / H1) between the lowest illuminance H1 near the center of the light guide and the highest illuminance H2 at the end is 1.63 in FIG. 6 and 2.53 in FIG. As described above, when the light scattering light guide 5 is not installed, the illuminance variation is 2.5 times or more, whereas the light emitting device 20 provided with the light scattering light guide 5 is 1.63 times as large. There is variation, and uniformization of the emitted light is achieved.

(Optical Element of Second Embodiment and Light Emitting Device of Second Embodiment Using the Same)
FIG. 10 shows that the same light-scattering particles as those contained in the light-scattering light-guiding unit 5 are not made transparent, except for the light-guiding member 1 other than the light-scattering light-guiding unit 5. FIG. 7 is a diagram showing the distribution of brightness in the same manner as in FIG. 6 for the light emitting device of the second embodiment having the same configuration as the light emitting device 20 except that it is contained in a concentration lower than 5. FIG. In the following description, in describing the light guide of the second embodiment and the light emitting device of the second embodiment using the light guide, the light guide 1 of the first embodiment and the first using the light guide Constituent elements corresponding to the light emitting device 20 of the first embodiment are denoted by the same reference numerals.

  Comparing FIG. 6 and FIG. 10, the light emitting device of the second embodiment is also emitted from both ends of the light guide (the optical element of the second embodiment corresponding to the light guide 1). It can be seen that the light intensity is suppressed. As with the light guide 1, the irradiation range of the suppressed amount of light is widened. Therefore, the light emitting device of the second embodiment can also irradiate light with substantially uniform intensity over the entire light guide (the optical element of the second embodiment corresponding to the light guide 1). It has become. Specifically, the ratio (H2 / H1) between the minimum illuminance H1 near the center of the light guide and the maximum illuminance H2 at the end (H2 / H1) is 2.26, compared to 2.53 in the case of FIG. It is a small value.

  Here, the light scattering particles contained in portions other than the light scattering light guide 5 are turbidity τ, which is a scattering parameter corresponding to the scattering coefficient, in the axial direction of the light guide of the second embodiment described above. When the length is L, the average number of scattering times indicating the average number of scattering times is in the range of 0 <L / (2 × τ) <60.

(Optical element of the third embodiment and light emitting device of the third embodiment using the optical element)
FIG. 11 is a schematic view showing the cross section of the light emitting device 20A of the third embodiment having the same configuration as the light emitting device 20 except that the shape of the prism portion 4 is changed, as in FIG. 5 is a diagram in which the illustration of 5 is omitted. FIG. 11 also shows an enlarged view of the prism portion 4A of the light guide 1A of the light emitting device 20A at the longitudinal end and the longitudinal center of the light guide 1A. The prism portion 4A is a prism having a triangular cross section. The angle of the reflecting surfaces 4A1 and 4A2 with respect to the line N connecting the apexes 10A of the prisms, and the angle of the reflecting surface 4A1 that reflects incident light from one longitudinal end P side is denoted by A. Note that the shape of the prism portion 4A of the illumination device 20A of the third embodiment can also be applied to the illumination device of the above-described comparative example that does not have the light scattering light guide 5. In the following, in the description of the light guide 1A of the third embodiment and the light emitting device 20A of the third embodiment using the same, the light guide 1 of the first embodiment and the light guide 1A will be used. The components corresponding to the light emitting device 20 of the first embodiment are denoted by the same reference numerals except for the prism portion 4A, the emission surface 6A, and the vertex 10A.

  The angle of the reflecting surface 4A2 that reflects the incident light from the other longitudinal direction end Q side is defined as B. At that time, the prism portion 4A satisfies A <B in the region PA close to one longitudinal direction end portion P, and A> B in the region QA close to the other longitudinal direction end portion Q. . And in the area | region RA of the longitudinal direction center of 1 A of light guides, it is set to A = B. The lengths of these areas PA, QA, and RA are the same, but may be PA: QA: RA = 2: 1: 1 or 3: 3: 1. Further, regarding A <B, A> B, which is the relationship between angles A and B, the angles A and B may be the same, but in the area PA, the angle A is gradually increased as the distance from the end portion P increases. Alternatively, the angle B may be gradually decreased, and in the region QA, the angle A may be gradually decreased and the angle B gradually increased as the distance from the end Q is increased.

  In the area PA, as shown in the enlarged view on the right side of FIG. 11, with respect to a line N ′ parallel to the light line N when the light incident from one longitudinal direction end portion P side irradiates the reflecting surface 4A1. There is a high probability that the crossing angle C is larger than the crossing angle D with the light line N ′ when light incident from the other longitudinal direction end Q side irradiates the reflecting surface 4A2. In the area PA, the reflecting surface 4A1 and the LED 21 on the end P side are close to each other, and the light totally reflected by the exit surface 6 near the end P or the light directly guided from the incident lens 3 is a line. This is because it has a large crossing angle with respect to N ′. Further, in the area PA, the reflecting surface 4A2 and the LED 21 on the end Q side are far from each other, and the light that irradiates the reflecting surface 4A2 inevitably has a small intersection angle with the line N ′. Therefore, by reducing the angle A of the reflection surface 4A1, the light from the end portion P side and redirected can be made substantially perpendicular to the emission surface 6A. Further, by increasing the angle B of the reflecting surface 4A2, the light from the end Q side and whose direction has been changed can be made substantially perpendicular to the exit surface 6A.

  Similarly, in the region QA, as shown in the enlarged view on the left side of FIG. 11, light N incident from one longitudinal end P side irradiates the reflecting surface 4A1, and is a line N ′ parallel to the line N of that light. Is likely to be smaller than the intersection angle D with the light line N ′ when light incident from the other longitudinal direction end Q side irradiates the reflective surface 4A2. In the region QA, the reflecting surface 4A2 and the LED 21 on the end Q side are close to each other, and the light totally reflected by the emitting surface 6 near the end Q or the light directly guided from the incident lens 3 is a line. This is because it has a large crossing angle with respect to N ′. In the region QA, the reflecting surface 4A1 and the LED 21 on the end P side are far from each other, and the light that irradiates the reflecting surface 4A1 inevitably has a small intersection angle with the line N ′. Therefore, by increasing the angle A of the reflecting surface 4A1, the light from the end Q side and redirected can be made substantially perpendicular to the exit surface 6A. In addition, by reducing the angle B of the reflecting surface 4A2, the light from the end P side that has been redirected can be made substantially perpendicular to the exit surface 6A.

  In the region RA at the center in the longitudinal direction, the crossing angle C with respect to the light line N ′ when light incident from one longitudinal direction end P side irradiates the reflecting surface 4A1 is the other longitudinal direction end. In many cases, when light incident from the Q side irradiates the reflecting surface 4A2, the crossing angle D of the light with respect to the line N ′ is substantially equal. Therefore, the angle is changed by making the angle A of the reflecting surface 4A1 and the angle B of the reflecting surface 4A2 equal and guiding both lights to the emitting surface 6A side so as to be perpendicular to the emitting surface 6A. The light after being made can be made substantially perpendicular to the exit surface 6A.

  FIG. 12 is a diagram illustrating light emission directions of the illumination device 20 according to the first embodiment and the illumination device 20A according to the third embodiment. The illumination device 20 has a large amount of light emitted outward in the areas PA and QA close to the both ends P and Q in the longitudinal direction, and the long area in the central area RA in the longitudinal direction. More light is emitted in the direction orthogonal to the direction. The illuminating device 20A has a large amount of light emitted in a direction orthogonal to the longitudinal direction in all the regions PA and QA on both ends P and Q sides in the longitudinal direction and the central region RA in the longitudinal direction. ing. That is, in the illumination device 20A, the light emission direction is substantially perpendicular to the emission surface 6A in the entire range of the light guide 1A.

(Main effects obtained by the embodiment of the present invention)
The light emitting devices 20, 20A, and the light emitting device according to the second embodiment (these are collectively referred to as the light emitting device 20, etc.), the light guides 1, 1A, and the light guide according to the second embodiment. The body (collectively referred to as the light guide 1 or the like) has scattered and entered the emitted light into the longitudinal direction end region of the light guide 1 or the like on the exit surfaces 6 and 6A. A light scattering light guide 5 that contains light scattering particles that guide most of the light to the rear side and emits most of the incident light from the exit surfaces 6 and 6A is provided as a part of the light guide 1 and the like. Therefore, strong light emission in the longitudinal direction end region of the light guide 1 or the like can be scattered, and light emission from the light guide 1 or the like can be made uniform. Moreover, since all the light guide parts including the light-scattering light guide part 5 can be used as the light emission area, the light emitting device 20 and the light guide body 1 and the like can be downsized.

  In addition, since the light emitting device 20 and the like are arranged by shifting the LED 21 to the prism portion 4 side, the central portion of the light guide 1 and the like can be made to emit light stronger than usual, and the emitted light can be made uniform. it can. However, since the intensity of light at the center does not reach the intensity at both ends, it is preferable as a light source for a scanner that requires the intensity of light at the ends. In addition, the light emitted from the light intensity uniformized over the entire range is obtained by shortening the length of the light guide 1 or the like in the longitudinal direction or increasing the scattering degree of the light scattering light guide 5. Can do. In such a case, it can be used instead of an elongated fluorescent lamp.

  Further, portions of the light guides 1 and 1A other than the light scattering light guide 5 are made transparent, so that both end portions in the longitudinal direction are not particularly dazzled, and the light guide 1 , 1A can be irradiated with light having a substantially uniform intensity. Moreover, parts other than the light-scattering light guide part 5 among the light guides 1 and 1A are made transparent, thereby increasing the light emission amount of the central part in the longitudinal direction of the light guides 1 and 1A. be able to. Further, in the light guide body according to the second embodiment, the part other than the light scattering light guide unit 5 includes light scattering particles in the transparent body at a lower content rate than the light scattering light guide unit. Thus, both end portions in the longitudinal direction are not particularly dazzled, and light with a substantially uniform intensity can be irradiated over the entire light guide according to the second embodiment.

  In addition, an incident lens 3 that is a flat surface 7 on the end surface in the longitudinal direction of the light guide 1 and the like and that swells from the end portion in the longitudinal direction is disposed at the center. The light emitted from the LED 21 by the incident lens 3 enters the light guide 1 and the like as light close to parallel light. Therefore, the light at both end portions in the longitudinal direction of the light guide 1 and the like is reduced, the light guided to the center side is increased, and the emitted light is made uniform. Further, since it is close to parallel light but not completely parallel light, the light reflected by the same prism surface in the prism portion 4 includes light having a slightly different incident angle, thus avoiding the following problems. can do. That is, if the light is completely parallel light, a portion with a small amount of reflected light is generated between the light reflected by the surfaces of the adjacent prism portions 4 and 4A, and a strong and weak stripe distribution is generated in the emitted light. However, since non-parallel light is mixed, such a problem can be prevented. As shown in FIG. 2, the light scattering light guide 5 is provided so as to extend in the longitudinal direction of the light guide from the flat surface 7 other than the portion where the incident lens 3 is disposed. As shown in FIG. 4, most of the light that passes directly from the LED 21 through the incident lens 3 is emitted from the center portion of the light guide 1 and the like, not from both ends. This configuration prevents light from being scattered and not emitted from the central portion of the light guide 1 or the like.

  Further, the light guide 1A has the shape of the prism portion 4A shown in FIG. 11 as described above. Therefore, in the entire range of the light guide 1A, the light emission direction can be made substantially perpendicular to the emission surface 6A, and the light emission from the light guide 1A can be made more uniform. Note that, by appropriately selecting the angles A and B of the prism portion 4A, all the emission directions can be set to directions that are not perpendicular to the emission surface 6A.

  Further, the light scattering particles contained in the light scattering light guide 5 such as the light guide 1 have an average scattering frequency value indicating the average scattering frequency when turbidity, which is a scattering parameter corresponding to the scattering coefficient, is τ. The length α / 2 of the light scattering light guide 5 is within the range of 5 <α / (2 × τ) <50. This makes it possible to appropriately scatter strong light emitted from both ends of the light guide 1 or the like, and make light emitted from the light guide 1 or the like more uniform.

  The axial length α / 2 of the light scattering light guide 5 is within the range of L / 30 <α / 2 <L / 4 with respect to the axial length L of the light guide 1 and the like. Has been. Accordingly, light in a range where strong light emitted from both ends of the light guide 1 and the like is emitted can be sufficiently scattered by the light scattering light guide 5. Then, excessive scattering of the emitted light can be suppressed, and the uniformity of the emission of light from the light guide 1 or the like can be prevented.

  Further, the thickness t of the light scattering light guide 5 described above is in the range of T / 20 <t <T / 2 with respect to the thickness T of the light guide 1 and the like. Accordingly, it is possible to secure a suitable thickness of the light scattering light guide 5 in order to appropriately scatter strong light emitted from both ends of the light guide 1 and the like.

  Further, in the light guide according to the second embodiment, the above-described turbidity τ value of the light scattering light guide 5 is used as the light guide according to the second embodiment other than the light scattering light guide 5. It is larger than the body value. Therefore, it is possible to suppress a decrease in the amount of light emitted from the central portion of the light guide located at a position away from the LED 21 that is the light source due to excessive scattering.

  Moreover, parts other than the light-scattering light guide part 5 and the light-scattering light guide part 5 among the light guides 1 etc. are united by 2 material shaping | molding. Therefore, both can be handled as a unit, and the handleability is excellent.

(First modification)
FIG. 13 is a side view corresponding to FIG. 2 of the light emitting device 20B of the first modification example of the light emitting device 20 and the like. About each component of the light-emitting device 20B, the component corresponding to the light-emitting device 20 is attached | subjected with the code | symbol same as it. The light emitting device 20B has the same configuration as the light emitting device 20 except that the emission surface 6 is a flat surface. With such a configuration of the light emitting device 20B, the light emitted from the emission surface 6 does not have a linear shape parallel to the optical axis M1 at a position away from the emission surface 6 by a predetermined distance. Will spread in the short direction. In addition,
The thickness dimension t of the light-scattering light guide 5 in the direction perpendicular to the emission surface 6 at the center in the short direction of the light guide 1 or the like is shorter than the thickness of other parts as shown in FIG. Note that the light scattering light guides 5 in FIG. 13 may all have the same thickness dimension t in the short direction.

(Second modification)
FIG. 14 is a side view corresponding to FIG. 2 of the light emitting device 20C of the second modification example of the light emitting device 20 and the like. About each component of 20 C of light-emitting devices, the code | symbol same as it is attached | subjected to the component corresponding to the light-emitting device 20. FIG. The light emitting device 20C has the same configuration as the light emitting device 20 except that the emission surface 6 is a concave surface. With such a configuration of the light emitting device 20 </ b> C, light emitted from the emission surface 6 is further spread in the short direction of the light guide 1 and the like. In addition, as shown in FIG. 14, the thickness dimension t of the light-scattering light guide part 5 of the direction orthogonal to the output surface 6 in the center part of the short direction of the light guide 1 etc. is shorter than the thickness dimension of other parts. . Note that the light-scattering light guide 5 in FIG. 14 may have a lower surface in the short length direction that is not curved but linear.

  Such light emitting devices 20B and 20C in which light emitted from the emission surface 6 spreads in the short direction of the light guide 1 or the like are more suitable for applications such as lighting devices. On the other hand, when a sheet is gathered at a predetermined distance from the exit surface 6 and a sheet is placed at that position, the light emitting device 20 on which a linear illumination state parallel to the optical axis M1 is projected is, for example, for a scanner It is more suitable for applications such as light sources.

(Other forms)
The optical element (light guide 1 and the like), the light emitting device 20 and the like, and the light emitting devices 20B and 20C in the embodiment of the present invention have been described above, but various modifications can be made without departing from the gist of the present invention. For example, as the optical element, the light guide portion may be formed in a cylindrical shape. Further, for example, the light emitting device may be configured by adding a reflecting member such as an umbrella of a light bulb.

  The light emitting device 20 and the like, the light emitting devices 20B and 20C, and the light guide 1 according to the embodiment of the present invention are incident on the rod-shaped light guide 1 and the like and the light guide 1 and the like from the end in the longitudinal direction. The emitted light is emitted from the emission surfaces 6 and 6A, and the emitted light is multiply scattered and incident on the long-side end region of the light guide 1 or the like on the emission surfaces 6 and 6A. A light scattering light guide 5 that contains light scattering particles guided to the rear side and emits most of the incident light from the exit surfaces 6 and 6A is provided as a part of the light guide 1 or the like. Further, the light emitting device 20 and the like, and the light emitting devices 20B and 20C have an LED 21 that makes light incident on the light guide 1 and the like, and a mirror member 22. However, the mirror member 22 can be omitted. However, from the viewpoint of effectively using the light emitted from the LED 21, the light emitting device 20 and the like and the light emitting devices 20 </ b> B and 20 </ b> C preferably include the mirror member 22. Further, even when the light emitting device 20 or the like and the light emitting devices 20B and 20C include the mirror surface member 22, the mirror surface member 22 has a cup shape in which the longitudinal section in FIG. 5 draws a parabolic curve. It is not necessary and may have other shapes such as a spherical shape. In addition, the light emitting member is not limited to the chip type LED 21, and other light emitting members such as a discrete type LED and an organic EL element can be employed.

  Further, in the light emitting device 20 and the like, and the light emitting devices 20B and 20C, the LED 21 is shifted to the prism portions 4 and 4A side. However, the LED 21 may be arranged shifted to the emission surfaces 6 and 6A side. Moreover, you may make it LED21 irradiate light with respect to the incident lens 3 toward the diagonally upper side from the lower side of FIG. For example, the center line of the light emitted from the LED 21 may be tilted by 45 ° or 20 °, not parallel to the central axis (optical axis M1) of the light guide 1 or the like. Further, the LED 21 used in the light emitting device 20 and the like and the light emitting devices 20B and 20C is arranged at an intermediate position between the central axis (optical axis M1) of the light guide 1 or the like and the emission surfaces 6 and 6A. It may be tilted at an angle of 45 ° (tilt amount) with respect to the central axis (optical axis M1) of the light guide 1 or the like in the direction of 4, 4A. These shift positions and tilt amounts can be changed as appropriate. For example, the shift position is a prism extending from the central axis (optical axis M1) of the light guide 1 etc. and extending from the central axis (optical axis M1) of the light guide 1 etc. It can be appropriately set on a line orthogonal to the portions 4 and 4A. Further, the tilt amount is such that the light emitting surface of the LED 21 is directed toward the central axis (optical axis M1) of the light guide 1 etc. from a state where the light emitting device 20 or the like and the light emitting devices 20B and 20C are not tilted at all. The angle may be appropriately set in the range of 5 ° to 85 °.

  Moreover, parts other than the light-scattering light guide part 5 among the light guides 1 and 1A are made into the transparent body. This transparent body may be colorless and transparent or colored and transparent. Moreover, this is the same also about the part except the light-scattering particle | grains of parts other than the light-scattering light guide part 5 of the light guide which concerns on 2nd Embodiment. The ratio (H2 / H1) between the minimum illuminance H1 near the center of the light guide and the maximum illuminance H2 at the end is preferably between 1.2 and 2.3 for scanners, and preferably between 1.4 and 2 A range of 0.0 is more preferred. For normal illumination, H2 / H1 is preferably in the range of 1.1 to 1.7, more preferably in the range of 1.2 to 1.4. This is because when the value of H2 / H1 is made small, it is necessary to decrease the brightness at both ends or increase the brightness at the center, but such a device often decreases the overall light efficiency. The value of H2 / H1 is preferably 1.1 or more.

  In addition, an incident lens 3 that is a flat surface 7 on the end surface in the longitudinal direction of the light guide 1 and the like and that swells from the end portion in the longitudinal direction is disposed at the center. However, the flat surface 7 can be omitted, and the entire longitudinal end surface of the light guide 1 or the like can be used as the incident lens 3. Such an example is shown in FIG. The left side of FIG. 15 is a side view showing the configuration of such a light guide, and corresponds to FIG. Further, the right side of FIG. 15 is a front view showing the configuration of the end portion of such a light guide, and corresponds to a part of FIG. Further, the incident lens 3 can be omitted, and the entire end face in the longitudinal direction of the light guide 1 or the like can be the flat surface 7. Furthermore, even when the incident lens 3 is provided on the end face in the longitudinal direction of the light guide 1 or the like, the periphery thereof may not be a flat flat surface 7 but may be another shape such as a truncated cone side surface.

  Further, the light guide 1 other than the light guide 1A has a prism portion 4 and the light guide 1A has a prism portion 4A shown in FIG. However, the direction changing portion that changes the direction of light is not provided with the sawtooth prism portions 4 and 4A, but a member that reflects light such as a mirror, a white surface, or the like is provided on the bottom surface without tilting or tilting the bottom surface. May be.

  In addition, the light scattering particles contained in the light scattering light guide 5 have an average scattering frequency value indicating the average scattering frequency when turbidity, which is a scattering parameter corresponding to the scattering coefficient of the light scattering light guide 5, is τ. However, with respect to the length α / 2 of the light scattering light guide 5 described above, the range is 5 <α / (2 × τ) <50. The axial length α / 2 of the light scattering light guide 5 is within the range of L / 30 <α / 2 <L / 4 with respect to the axial length L of the light guide 1 described above. It is said. Furthermore, the thickness t of the light scattering light guide 5 described above is within the range of T / 20 <t <T / 2 with respect to the thickness T of the light guide 1 described above. However, these ranges can be appropriately changed depending on the size, length, material used, and the like of the light emitting device 20 and the like, the light emitting devices 20B and 20C, and the light guide 1 and the like.

  Further, in the light guide according to the second embodiment, the above-described turbidity τ value of the light scattering light guide 5 is used as the light guide according to the second embodiment other than the light scattering light guide 5. It is larger than the body value. However, depending on the size, length, material used, and the like of the light-emitting device 20 and the like, the light-emitting devices 20B and 20C, and the light guide 1 and the like, these ranges may be light scattering in the light guide according to the second embodiment. The value of the above turbidity τ of the light guide 5 can be made smaller than the value of the light guide according to the second embodiment other than the light scattering light guide 5. For example, in the case where the amount of light emitted from the central portion is larger than the end portion in the longitudinal direction of the light guide according to the second embodiment, the second embodiment other than the light scattering light guide 5 is used. By increasing the value of the turbidity τ of the light guide according to the embodiment, it is possible to obtain a uniform amount of emitted light over the entire light guide.

  Further, the light guide 1 and the like are made of PMMA, but other acrylic ester or methacrylic ester polymer, which is a highly transparent amorphous synthetic resin such as an acrylic resin or polystyrene. In addition, other translucent resins such as polycarbonate or glass or the like can be used. Further, the incident lens 3 functions as a parallel light forming body. In order to obtain the same parallel light forming body, for example, when the LED 21 is arranged in the direction opposite to the light guide 1 or the like, the mirror member 22 becomes the parallel light forming body. In this way, the concave reflecting mirror may be a parallel light forming body.

  Various conditions such as the material, shape, and particle size of the light scattering particles can be set as appropriate. For example, the light scattering particles are spherical and translucent silicone particles having a particle diameter of 2 μm to 9 μm. However, as the light scattering particles, various particles can be used regardless of the material, shape, particle diameter, and the like as long as the light in the light transmissive member 1 is subjected to multiple scattering. However, in order for the light scattering light guide 5 to increase the forward scattering of incident light within an appropriate range, spherical and translucent silicone particles having a particle diameter of 2 μm to 9 μm, more preferably 5 μm to 9 μm, should be used. Is preferred.

  In order to make the forward scattering of the incident light (= scattering in the same direction as the incident light) appropriate, it is also important to adjust the mean free path of the light incident on the inside of the light guide 1 or the like. is there. For example, when the thickness of the light scattering light guide 5 is t as described above, the mean free path is preferably in the range of “(1/4) × t” to “(1/2) × t”. By setting the mean free path to be equal to or greater than “(1/4) × t”, it is possible to suppress a decrease in the efficiency of outgoing light with respect to incident light without excessively increasing backscattering. By setting the mean free path to be equal to or less than “(1/2) × t”, it is possible to appropriately suppress the stripe distribution of light intensity without excessively increasing the forward scattering. This is particularly true when spherical and translucent silicone particles having a particle diameter of 2 to 9 μm or 5 to 9 μm are used as the light scattering particles.

  Moreover, it is good also as arrange | positioning LED21 and / or the incident lens 3 only to one end instead of both ends of the light guide 1 grade | etc.,. Further, two or more LEDs 21 and / or incident lenses 3 may be disposed at both ends or one end of the light guide 1 or the like.

1,1A Light guide (optical element)
3 Incident lens (convex lens)
4,4A Prism part (direction changing part)
5 Light Scattering Light Guide 6, 6A Emission Surface 7 Flat Surface 20, 20A, 20B, 20C Light Emitting Device 21 LED (Light Source)
A Angle of reflecting surface that reflects incident light from one longitudinal end B Angle of reflecting surface that reflects incident light from the other longitudinal end τ Turbidity (scattering coefficient, scattering parameter)
α Length of light scattering light guide in the central axis direction L Length of light guide in the axial direction t Thickness of light scattering light guide in a direction perpendicular to the emission surface at the center in the short direction of the light guide T Of the light guide in the direction perpendicular to

Claims (16)

And the rod-shaped light guide section, a light source for incident light to the light guide section, the light-emitting device emitted from the emitting surface light incident from the longitudinal direction end portions of the light guide section,
Wherein the longitudinal direction end portion side of the light guide section contains a light scattering particle directing much of the light has the light the exit to and incident to multiple scattering in the same direction as the incident direction, of light entering the light scattering guide to emit is provided et be from the exit surface increases,
The light exiting surface of the light guide and the light scattering light guide is a flat surface or a concave surface that is recessed from both ends in the short direction of the light guide toward the center.
A light emitting device characterized by that.   In a light emitting device that emits light incident from an end portion in the longitudinal direction of the light guide portion from an exit surface, a rod-shaped light guide portion, a light source that makes light incident on the light guide portion,
  The light guide unit includes light scattering particles on the end side in the longitudinal direction that contain light scattering particles that multiple-scatter the emitted light and guide most of the incident light to the same direction side as the incident direction. A light scattering light guide that emits a large amount from the exit surface is provided,
  Outgoing surfaces of the light guide and the light scattering light guide are convex surfaces that bulge from both ends in the short direction of the light guide toward the center.
A light emitting device characterized by that. The light-emitting device according to claim 1 or 2 ,
Further comprising a direction changing portion that changes the direction of light incident from the end in the longitudinal direction so as to face the exit surface;
The light source by shifting the side away from the side or the direction changing portion from the central axis closer to the turning portion of the light guide portion, the emission of the light incident on the light guide unit light guide portion emitting apparatus characterized by being configured to face the surface or the direction changing section. The light emitting device according to any one of claims 1 to 3,
A light emitting device characterized in that a mirror surface member having a parabolic reflecting surface for reflecting light emitted from the light source to the light guide portion side is provided on an end portion side in the longitudinal direction of the light guide. apparatus. And the rod-shaped light guiding portion, the light incident from the longitudinal direction end portion of the light guide portion and a turning unit for turning said from the exit surface arranged to face the turning portion In the optical element that emits the light redirected by the direction changer,
Wherein one of the emission surface, in the longitudinal direction end portion side of the light guide section contains the light scattering particles leading to much of the light has the light the exit to and incident to multiple scattering in the same direction as the incident direction as provided et been partially light scattering guide to many emitted from the exit surface of light entering of the light guide unit,
The light exiting surface of the light guide and the light scattering light guide is a flat surface or a concave surface that is recessed from both ends in the short direction of the light guide toward the center.
An optical element.   It has a rod-shaped light guide part and a direction changing part that changes the direction of light incident from the end in the longitudinal direction of the light guide part, and the light emitting part is arranged so as to face the direction changing part. In the optical element that emits the light redirected by the direction changer,
  Of the exit surface, the longitudinal end portion side of the light guide part contains light scattering particles that multiple-scatter the emitted light and guide most of the incident light to the same direction side as the incident direction. A light scattering light guide that emits most of the incident light from the exit surface is provided as a part of the light guide,
  Outgoing surfaces of the light guide and the light scattering light guide are convex surfaces that bulge from both ends in the short direction of the light guide toward the center.
An optical element. The optical element according to claim 5 or 6 ,
Of the light guide part, the part other than the light scattering light guide part is a transparent body, or the light scattering particles are included in the transparent body at a lower content than the light scattering light guide part. An optical element characterized by the above. The optical element according to any one of claims 5 to 7 ,
Convex lens-shaped incident lenses are arranged on both end surfaces in the longitudinal direction of the light guide portion so as to swell from the end portions in the longitudinal direction,
Said light scattering guide, the optical element characterized in that from the end surface other than a portion where the incident lens is disposed is provided so as to extend in the longitudinal direction of the light guide portion. The optical element according to any one of claims 5 to 8 ,
The light scattering light guides are provided at both ends of the light guide part,
The direction changing part is a prism having a triangular cross section,
The angle of the reflecting surface with respect to the line connecting the apexes of the prisms, and the angle of the reflecting surface that reflects the incident light from one of the longitudinal ends is A, and the incident from the other longitudinal end. When the angle of the reflecting surface for reflecting the light is B, A <B in the one longitudinal end region, A> B in the other longitudinal end region,
An optical element characterized in that A = B in the central region in the longitudinal direction of the light guide. The optical element according to claim 9 , wherein
The light scattering particles contained in the light scattering light guide are turbidity, which is a scattering parameter corresponding to a scattering coefficient, τ, and the length in the central axis direction of each light scattering light guide is α / 2. When the average scattering number value indicating the average number of scattering is
5. An optical element characterized by being in a range of 5 <α / (2 × τ) <50. The optical element according to claim 10 , wherein
Of the light guide part, the part other than the light scattering light guide part also includes the light scattering particles,
The light scattering particles contained in the portion other than the light scattering light guide unit, when the turbidity which is a scattering parameter corresponding to a scattering coefficient is τ, and the axial length of the light guide unit is L, The average scattering count value indicating the average scattering count is
An optical element having a range of 0 <L / τ <60 and an average number of scattering times of the light scattering light guide being larger than a value of a light guiding part other than the light scattering light guide . The optical element according to claim 9 , wherein
An optical element, wherein a value of turbidity, which is a scattering parameter corresponding to a scattering coefficient of the light scattering light guide, is made larger than a value of the light guiding part other than the light scattering light guide. The optical element according to any one of claims 5 to 12 ,
When the total axial length of the light scattering light guide is α and the axial length of the light guide is L,
An optical element characterized by being in a range of L / 15 <α <L / 2. The optical element according to any one of claims 5 to 12 ,
The thickness t of the light-scattering light guide in the direction perpendicular to the exit surface at the center in the short direction of the light guide is when the thickness of the light guide in the direction perpendicular to the exit surface is T,
An optical element characterized by being in a range of T / 20 <t <T / 2. An illumination device comprising: the optical element according to claim 5 ; and light sources disposed at both ends or one end of the optical element. The lighting device according to claim 15 .
The lighting device is characterized in that the light source is an LED, and the LED is disposed at a position approaching a surface opposite to the emission surface from the center of the end in the longitudinal direction of the optical element.

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