JP4995110B2 - Light source device - Google Patents

Description

  The present invention relates to a light source device including a light guide plate for introducing light from a light source from an end surface and emitting the light from a side surface.

  Conventionally, a light source device using a fluorescent lamp or the like has been widely used. Recently, proposals for replacing an existing lamp such as a fluorescent lamp with a light emitting diode (hereinafter referred to as LED) have been made in various fields. . Unlike fluorescent lamps, LEDs do not use mercury, are small in size and can be driven with low power, and in recent years their luminous efficiency has been dramatically improved. The shape of conventional LED devices has been mainly a shell type, but the surface mount type gradually increases, and the LED devices are miniaturized, so that their use is widely expected. Until now, LEDs have been often used for display of indicators and the like, but with the improvement in efficiency, they have also been developed as lighting applications and are gradually becoming popular.

  Conventionally, for example, in order to realize a linear or planar light source using a small LED for a fluorescent lamp, a method of arranging a large number of LEDs at regular intervals is common. However, in this method, it is visually recognized that the light source emits light in a granular form, and the light source is not a smooth linear or planar light source. Therefore, it is possible to provide a smooth linear or planar light source by arranging a sheet or plate having a diffusion effect on the front surface of the LED light source and diffusing the straight light of the LED. In this case, the diffusion sheet or plate Since the transmittance of light is about 60%, the light utilization efficiency is extremely reduced.

  In addition, when a linear or planar light source is realized by arranging LEDs, it is difficult to reduce the number of LEDs. If the light sources are arranged closely, the light sources are close to each other, so that the uniformity of light emission is good when it is linear or planar, but it is necessary to use more LEDs. On the other hand, in order to reduce the number of LEDs, it is necessary to arrange the LEDs at a coarse interval, and in this case, uniformity on the light emitting surface is impaired.

On the other hand, a linear light source using a light guide technique has been proposed as a light source for an image input apparatus such as a facsimile. For example, in Patent Document 1, light from a lamp is reflected by a concave reflecting mirror, the light is introduced from a cylindrical rod end surface made of a transparent material, and scattered in the rod to form a linear shape on the surface in the longitudinal direction of the rod. To get the light. Further, in Patent Document 2, a plurality of light emitting diode elements are arranged at one end of a cylindrical light guide, and a diffuse reflection part is linearly formed along the axial direction on the surface of the light guide. A cylindrical reflecting member is provided around the light portion, and linear light is obtained from a linear gap along the axial direction of the reflecting member.
JP-A-1-237534 Japanese Patent Laid-Open No. 9-9006

  As described above, when forming a linear light source using LEDs, there is a method realized by using a plurality of LEDs and arranging them in a row, but since this method uses a plurality of light sources, There is a problem that it becomes a linear light source with low brightness uniformity and is visually recognized as an aggregate of point light sources that shine in a granular manner depending on the interval at which the LEDs are arranged. At the same time, if there are variations in the light emission colors of the LEDs, there is a problem that not only the brightness but also the uniformity of the color tone is lowered due to the difference in chromaticity of adjacent LEDs.

On the other hand, in the above prior art, a method for realizing a highly uniform linear light source by using a light guide technique has been proposed for a light source for an image input device such as a facsimile. Only the technology is described.
For example, a linear light source as described above may be used as a sign light that prevents people from colliding with corners or corners of furniture, kitchens, walls, shelves, etc., or as an auxiliary light source that illuminates the back. . However, in both Patent Documents 1 and 2, a cylindrical rod is described as the light guide. When a linear light source formed by a cylindrical rod is to be built in a corner of furniture, kitchen, or the like as described above, the light source forms a circular arc, which causes a problem of protruding or creating a gap. If it protrudes, it will conflict with the effect of preventing people from colliding. On the other hand, if there is a gap, there will be a problem that if the gap is filled, the efficiency of light emission will be reduced. Will also occur. For this reason, in the prior art, there are many obstacles for incorporating the linear light source into the living space.

  Accordingly, an object of the present invention is to provide a light source device using a light guide plate that has good light emission uniformity and is suitable for being arranged at a corner or corner.

  The above object includes a light source and a light guide plate having a triangular cross-section for introducing light from the light source from an end face and emitting the light from one or two side faces, and the light guide plate has a length of the side face. This is achieved by a light source device having a diffuse reflection mechanism that is longer than the width of the end surface and that increases irregular reflection as the distance from the end surface is different from the side surface that emits the light.

  Here, the light guide plate may have a shape in which corners between at least one pair of two sides in the triangular cross section are chamfered by a straight line or a curve. The light guide plate has two sides in the triangular cross section corresponding to two sides in the triangular cross section corresponding to the two side faces emitting the light, or two side faces different from the side face emitting the light. It can have a shape in which the sides are replaced with arcs. The light source may be configured using one or more light emitting diodes. The light source can be configured using a white light emitting diode having an input power of 1 W or more. The light source is configured by using a plurality of light emitting diodes, and the plurality of light emitting diodes can be light emitting diodes having a plurality of different emission wavelengths.

  According to the present invention, it is possible to obtain a light source device using a light guide plate that has good light emission uniformity and is suitable for being arranged at a corner or corner. By making the light guide plate into a triangular prism shape, the light source device can be arranged at corners or corners of furniture, kitchens, wall surfaces, shelves and the like. By placing the luminescent material at a position that could not be placed in the past, it is possible to improve the sign effect or the decorativeness to prevent people from colliding with each other at the corner. On the other hand, if it is arranged in the corner, it can be used as an auxiliary light source for irradiating the back of a shelf that is difficult to illuminate conventionally. Furthermore, it is predicted that the corners of the light guide plate are caused by the corner edges of the light guide plate by chamfering the triangular corners of the light guide plate with straight lines or curves, or by changing the two triangular sides of the light guide plate to arc shapes. Accidents and injuries can be avoided.

  By using one or a plurality of LEDs as the light source, it is possible to obtain a light source device that is small, light, and energy-saving. Bright illumination can be obtained by using a white LED having an input power of 1 W or more. By using a plurality of LEDs having different light emission wavelengths, it is possible to improve the rendering effect or the decoration. Further, visibility can be improved by blinking or changing the color of the LED.

FIG. 1 is a diagram showing an embodiment of a light source device according to the present invention. FIG. 2 is an exploded view of the light source device of FIG.
In the present embodiment, as shown in the drawing, LED 1 as a light source, holding member 2 for holding LED 1, and a triangular cross section for introducing light from LED 1 from end face 25 and emitting it from side faces 26 and 27. And a light guide plate 3 having. The light guide plate 3 is disposed in the housing 4 via the reflection sheet 8. The housing 4 fixes the position of the light guide plate 3 and the holding member 2. The LED 1 is mounted on the substrate 9 and is held by the holding member 2 through the substrate 9. The side surface 28 different from the side surface from which the light is emitted from the light guide plate 3 is provided with a diffuse reflection mechanism (not shown) that is arranged from coarse to dense as the distance from the end surface 25 increases. This irregular reflection mechanism will be described later. The other end of the wiring 5 connected to the LED 1 is connected to a drive circuit 6 that drives the LED, and the drive circuit 6 is connected to a power source 7.

  During operation of the light source device, power is supplied to the drive circuit 6 from the power source 7, voltage is applied to the LED 1 by the drive circuit 6 via the wiring 5 and the substrate 9, and the LED 1 emits light. At this time, in order to stabilize the light emission amount of the LED 1, it is desirable that the drive circuit 6 operates by constant current control or constant voltage control. Light emitted by light emission from the LED 1 is introduced from the end face 25 of the light guide plate 3 and propagates through the light guide plate 3. The light propagating through the light guide plate 3 is irregularly reflected by a diffuse reflection mechanism (not shown) disposed in each part of the surface 28 of the light guide plate and is emitted from the side surfaces 26 and 27 of the light guide plate 3. This principle will be described later.

  The light guide plate 3 of this example is a triangular prism having a triangular cross section as shown in the figure, but may have other cross sections. This will be described later. The length L of the side surfaces 26 and 27 of the light guide plate 3 is configured to be longer than the width W of the end surface 25. Further, the size of the end face 25 is configured to be larger than the size of the light emitting portion 27 of the LED 1. In this way, light suitable for illumination with high luminance can be obtained by narrowing the width of the light guide plate, making the length long, and configuring the size of the end face to be larger than the size of the light source light emitting unit.

  Here, the size refers to both the thickness and width dimensions of the end face 25 of the light guide plate, and also refers to both the thickness and width dimensions of the light emitting portion 40 of the LED 1 (light source). As shown in FIG. 2, the width of the end face 25 of the light guide plate is W, the thickness is T, the width of the light emitting part 30 of the LED 1 is w, and the thickness is t as shown in FIG. Is configured to be larger than the size of the light emitting unit 40 of the LED 1 means that W> w and T> t.

  FIGS. 16A to 16C are views for explaining the size of the light emitting unit 40 of the LED 1. LED1 is provided with LED element 91 and the resin part which seals it. Since the light from the LED element 91 emits light through the resin portion, the resin portion is used as a light emitting portion here. FIG. 16A shows the size (width w, thickness t) of the light emitting unit 40 when there is one LED. FIG. 16B shows the size of the light emitting unit 40 when two LEDs are arranged horizontally. In this case, the width between the left end of the left light emitting unit and the right end of the right light emitting unit is defined as the width w of the light emitting unit 40. FIG. 16C shows a case where a total of four LEDs are arranged two by two in the vertical and horizontal directions. In this case, the thickness between the upper end of the upper light emitting unit and the lower end of the lower light emitting unit is defined as the thickness t of the light emitting unit 40. Even when the number of LEDs 1 increases, the width and thickness are determined in this manner.

  As described above, the side surface 28 of the light guide plate 3 includes the irregular reflection mechanism that is arranged from coarse to dense as the distance from the end surface 25 increases. The irregular reflection mechanism will be described in detail below. Before that, the principle of light propagation in the light guide plate 3 will be described first.

  FIG. 3 is a diagram illustrating a state in which light introduced from the LED propagates in the light guide plate. As shown in the figure, the light emitted from the LED 1 enters from the end face of the light guide plate 3. The light incident on the light guide plate 3 undergoes total reflection at the interface between the light guide plate and air due to the difference in refractive index between the light guide plate 3 and air. In order for total reflection to occur, it is necessary for light to strike the interface at an angle greater than the critical angle caused by the difference in refractive index between the light guide plate 3 and air, but at the time when light enters the light guide plate 3 from the LED 1. Since the light incident angle is within a certain angle due to the difference in refractive index, when the light hits the interface with the air from the light guide plate 3 described above, an angle greater than the critical angle is maintained. In order to maintain this relationship, it is desirable that the surface of the light guide plate be a smooth surface without irregularities.

  In order to emit light from the light guide plate 3 to the outside, that is, to the air, it is necessary to intentionally change the angle of light reflection by breaking the above-described total reflection. For this purpose, an irregular reflection mechanism is provided on the side surface 28 of the light guide plate 3. For example, the irregular reflection mechanism can be configured by a planar pattern or an uneven portion that irregularly reflects light arranged from coarse to dense as the distance from the end face 25 increases. By configuring the irregular reflection mechanism in this manner, irregular reflection can be increased as the distance from the end face 25 of the light guide plate 3 increases.

  FIG. 4 is a diagram showing an example in which a planar pattern is formed as a diffuse reflection mechanism on the light guide plate. In this example, the planar pattern is configured by the white silk print 10, but is not limited thereto, and may be other printing or application. Since no air layer is interposed between the light guide plate 3 and the silk print 10, there is no difference in refractive index between the light guide plate 3 and the air when the light in the light guide plate 3 hits the silk print 10. Further, it is customary to use a silk printing 10 having a low light transmittance and a high reflectance. Therefore, when the light from the inside of the light guide plate 3 hits the silk print 10, the silk print is white, so that scattering reflection occurs. Therefore, the light reflected in the direction of the side surfaces 26 and 27 facing the surface 28 on which the silk printing 10 is applied is incident on the side surface 26 or 27 at a critical angle or less, so that total reflection does not occur and light is transmitted from the side surfaces 26 and 27. Will be injected. The silk print 10 does not print on the entire back surface, and it is necessary to have a portion that is not printed by dots or lines. The light hitting the printed part is scattered and emitted from the side surfaces 26 and 27 as described above, and the light hitting the non-printed part maintains total reflection, and the light is guided in the direction farther from the light source. It will be illuminated. The printing area in the vicinity of the light incident part (end face 25) is reduced, and as the distance gradually increases, the ratio of the printing area is increased, that is, the area of the planar pattern is increased from coarse to dense as the distance from the end face 25 increases. It becomes possible to obtain light emission with high uniformity with respect to the light guide distance.

  FIG. 5 is a diagram illustrating an example in which an uneven portion is formed on the light guide plate as a diffuse reflection mechanism. In this example, the concavo-convex portion is constituted by the V-shaped groove 11, but is not limited to this, and may be, for example, textured. 5 is a groove formed by cutting or denting the light guide plate 3. When the light from the inside of the light guide plate 3 strikes the groove, the reflection angle changes and the light is emitted from the side surfaces 26 and 27. Similar to the silk printing in FIG. 4, the density and depth of the grooves are changed depending on the distance from the light incident part (end face 25), that is, the grooves are arranged from coarse to dense as they move away from the end face 25. High light can be obtained.

  As shown in FIGS. 4 and 5, by providing silk printing or grooves on the back surface of the light guide plate, light emission from the light exit surface can be obtained, but at the same time, light emission from the side surface portion of the light guide plate also occurs. , Light exiting in the rear direction is generated. Therefore, by covering the surfaces other than the light exit surface and the light entrance surface with a highly reflective member with the reflection sheet 8 shown in FIG. 2, it is possible to eliminate the leakage of light that escapes to the side surface and the back surface. However, since it is necessary to make an air layer exist between the reflection sheet 8 and the light guide plate 3, fixing by adhesion or the like is not desirable. Therefore, it is desirable to provide a mechanism for maintaining the positional relationship between the light guide plate 3 and the reflection sheet 8 by another member such as the housing 4. At the same time, since the positional relationship between the light guide plate 3 and the LED 1 needs to be held, the light guide plate 3, the reflection sheet 8, and the LED 1 are fixed by fixing the substrate 9 on which the LED 1 is mounted with the holding member 2 for attaching to the housing 4. A configuration that maintains the positional relationship can be realized.

It is also important to dissipate the heat generated by the LED 1. About this point, it becomes possible to make the whole housing | casing 4 bear a heat radiating mechanism by using metal members with favorable heat conductivity, such as aluminum, for the holding member 2 and the housing | casing 4. FIG.
If a white LED device is used for the LED 1, the embodiment of FIG. 1 is established as a white light source device. A brighter light source device can be realized by using a white light emitting LED having an input power of 1 W or more capable of supplying a large amount of power that has been commercialized or announced in recent years.
On the other hand, if an LED device having red, blue, and green LED elements in one package is used as LED1, a light source that realizes a variable color by controlling the current that flows through each of the red, blue, and green LEDs. An apparatus can be provided.

  FIG. 6 is a diagram showing an example of use of the present invention described in FIG. The light source device described above is assembled in the chase 30. The light source device is incorporated in the chest 30 and the side surfaces 26 and 27 serving as light emitting surfaces are exposed on the surface of the chest 30. As the light emitting surfaces 26 and 27 shine, the corners of the dresser 30 can be visually recognized in a dark room or the like, and it is possible to suppress a collision accident.

FIG. 7 is a diagram showing another embodiment of the light source device according to the present invention. FIG. 8 is an exploded view of the light source device of FIG.
As shown in the figure, the present embodiment includes an LED 1 serving as a light source, a holding member 2 for holding the LED 1, and a light guide plate 3 for introducing light from the LED 1 from the end face 25 and emitting it from the side face 31. . The light guide plate 3 is disposed in the housing 4 via the reflection sheet 8. The housing 4 fixes the position of the light guide plate 3 and the holding member 2. The LED 1 is mounted on the substrate 9 and is held by the holding member 2 through the substrate 9. At least one of the side surfaces 32 and 33 different from the side surface from which light is emitted from the light guide plate 3 is provided with an irregular reflection mechanism (not shown) that is arranged from coarse to dense as it is away from the end surface 25. This irregular reflection mechanism is as described above. The other end of the wiring 5 connected to the LED 1 is connected to a drive circuit 6 that drives the LED, and the drive circuit 6 is connected to a power source 7. The operation method is the same as the method shown in FIG.

  FIG. 9 is a diagram showing an example of use of the present invention described in FIG. The light source device described above is placed in the back corner of the storage 34. The light placed on the shelves 35 and 36 is illuminated by the light from the side surface 31 serving as the light-emitting surface, and the depth of the dark shelves becomes bright and convenience can be improved.

  10 and 11 show a shape in which the angle between two sides in a triangular cross section is chamfered by a straight line in the light guide plate described above. 12 and 13 show a shape in which the angle between two sides in a triangular cross section is chamfered by a curve such as an arc in the light guide plate described above. Here, the light guide plates in FIGS. 10 and 12 correspond to those in FIGS. 1 and 2, and the light guide plates in FIGS. 11 and 13 correspond to those in FIGS. By performing such chamfering, the corners are rounded and an accident that hurts a person can be suppressed. In this example, all the corners are chamfered, but at least one set of two sides may be chamfered by a straight line or a curve depending on the installation state of the light source device.

  14 has a shape in which two sides in a triangular cross section corresponding to two side surfaces (reference numerals 26 and 27 in FIG. 2) emitting light in the light guide plate of FIGS. FIG. 15 shows a shape in which two sides in a triangular cross section corresponding to two side surfaces (reference numerals 32 and 33 in FIG. 8) different from the side surface that emits light in the light guide plate of FIGS. Have Here, the circular arc shape includes a circular arc and a rounded shape similar to the circular arc. The light guide plate of FIG. 14 corresponds to that of FIGS. 1 and 2, and the light guide plate of FIG. 15 corresponds to that of FIGS. In this example, it is possible to obtain an effect similar to that of FIGS. 10 to 13 described above by using a circular arc to have a semicircular cross-sectional shape, for example.

  FIG. 17 shows another example of the shape of the light guide plate 3 used in the light source device of the present invention. In this example, the shape of the end surface 25 is different from the shape of the end surface 41 facing the end surface 25. With such a shape, it becomes possible to provide a light source device having a different light distribution characteristic in the longitudinal direction.

As described above, the problem that a large number of linearly arranged light sources appear to be grainy and the color non-uniformity caused by a conventional linear light source can be solved by using a light guide technology. Can do.
In addition, by configuring the light guide plate as a triangular prism, it is possible to improve the disposition property and to arrange the light source in an area where the space such as corners and corners is narrow.

  The present invention relates to a light source device including a light guide plate for introducing light from a light source from an end surface and emitting the light from a side surface, and has industrial applicability.

It is a figure which shows one Example of the light source device which concerns on this invention. It is an exploded view of the light source device of FIG. It is a figure which shows a mode that the light introduce | transduced from LED propagates the inside of a light-guide plate. It is a figure which shows the example at the time of forming a planar pattern as a diffused reflection mechanism in a light-guide plate. It is a figure which shows the example at the time of forming an uneven | corrugated | grooved part as a diffused reflection mechanism in a light-guide plate. It is a figure which shows the usage example of the light source device of FIG. 1 based on this invention. It is a figure which shows the other Example of the light source device which concerns on this invention. It is an exploded view of the light source device of FIG. It is a figure which shows the usage example of the light source device of FIG. 7 concerning this invention. It is an example of sectional drawing of the light-guide plate used for the light source device which concerns on this invention. It is an example of sectional drawing of the light-guide plate used for the light source device which concerns on this invention. It is an example of sectional drawing of the light-guide plate used for the light source device which concerns on this invention. It is an example of sectional drawing of the light-guide plate used for the light source device which concerns on this invention. It is an example of sectional drawing of the light-guide plate used for the light source device which concerns on this invention. It is an example of sectional drawing of the light-guide plate used for the light source device which concerns on this invention. (A)-(c) is a figure for demonstrating the size of the light emission part 27 of LED1. It is a figure which shows the other example of the light-guide plate used for the light source device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Holding member, 3 ... Light guide plate, 4 ... Housing, 5 ... Wiring, 6 ... Drive circuit, 7 ... Power supply, 8 ... Reflective sheet, 9 ... Substrate, 10 ... Silk printing, 11 ... V groove , 25 ... end face of the light guide plate, 26, 27, 28 ... side face of the light guide plate

Claims (6)

A light source and a light guide plate having a triangular cross-section for introducing light from the end surface and emitting it from one or two side surfaces, the light guide plate having a length of the side surface of the end surface A diffuse reflection mechanism that increases diffuse reflection as the distance from the end surface is longer than the side surface that emits the light and is different from the side surface that emits the light. A light source device, wherein the light source device is disposed and holds the positional relationship between the light guide plate and the reflection sheet so that the casing has an air layer between the reflection sheet and the light guide plate .
  2. The light source device according to claim 1, wherein the light guide plate has a shape in which corners between at least one pair of two sides in the triangular cross section are chamfered by a straight line or a curve.   The light guide plate has two sides in the triangular cross section corresponding to the two side faces that emit the light, or two sides in the triangular cross section that correspond to two side faces different from the side face that emits the light. The light source device according to claim 1, wherein the light source device has a shape replaced with an arc shape.   The light source device according to claim 1, wherein the light source is configured using one or a plurality of light emitting diodes.   The light source device according to claim 1, wherein the light source is configured using a white light emitting diode having an input power of 1 W or more.   The light source device according to claim 1, wherein the light source is configured by using a plurality of light emitting diodes, and the plurality of light emitting diodes are light emitting diodes having a plurality of different emission wavelengths.

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