JP2009026708A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device using a light guide having good light emitting uniformity and good light emitting efficiency. <P>SOLUTION: The light source device comprises a light source (LED) 1, a holding member 2 for holding the LED 1, and the light guide 3 for introducing light from the LED 1 through an end face 25 and emitting it from a side face 26. The light guide 3 has the side face 26 whose length is greater than the width of the end face 25, and the end face 25 whose size is greater than the size of a light emitting part 27 of the LED 1. The light guide 3 has a silk-printing or V-groove diffuse reflection mechanism arranged on a face 28 opposite to the side face 26 so as to be gradually denser as being farther from the end face 25. <P>COPYRIGHT: (C)2009,JPO&INPIT

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 conventional technique, a method of realizing a linear light source with high uniformity by using a light guide technique has been proposed for a light source for an image input device such as a facsimile, but its luminous efficiency is sufficient. That's not true. If the light emitting area of the light source part is made larger than that of the light guide entrance part, the light entrance efficiency to the light guide is significantly reduced. If there is a lot of light loss before entering the light guide, the light emission efficiency of the light source device becomes extremely poor. Further, when considered as a light source device including a housing, since the light source portion becomes large, there is a problem that the fluorescent lamp is not suitable for use as an alternative light source or lighting fixture.

  Accordingly, an object of the present invention is to provide a light source device using a light guide plate having good light emission uniformity and good light emission efficiency.

  The object includes a light source, a holding member for holding the light source, and a light guide plate for introducing light from the light source from an end surface and emitting the light from the side surface, and the light guide plate has a length of the side surface. Is a diffuse reflection mechanism that is longer than the width of the end face and has a size that is larger than the size of the light emitting portion of the light source, and that is arranged from coarse to dense on the surface facing the side face as the distance from the end face increases. This is achieved by the light source device provided.

  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 may be configured using a plurality of light emitting diodes, and the plurality of light emitting diodes may be light emitting diodes having a plurality of different emission wavelengths. The thickness of the light guide plate is preferably 4 mm or more. It is preferable that the holding member has a function of radiating heat generated by the light source. The light guide plate may be a polygonal column.

  The lamp device according to the present invention may include the light source device and a base having the same shape as the straight tube fluorescent lamp disposed at both longitudinal ends of the light source device. In addition, the lamp device according to the present invention can include at least one light source device, a drive circuit that drives the light source device, and a light bulb base for supplying power to the drive circuit. Here, a housing for housing the drive circuit is provided, and the housing and the bulb base can be configured integrally. The lamp device according to the present invention can include at least one light source device, a drive circuit that drives the light source device, and a ceiling mounting member that supplies power to the drive circuit from the ceiling.

  According to the present invention, it is possible to obtain a light source device using a light guide plate having good light emission uniformity and good light emission efficiency. By using one or a plurality of LEDs, it is possible to reduce the size and weight and save energy. 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. When the thickness of the light guide plate is 4 mm or more, the luminous efficiency can be improved even when a high-power LED having a large size is used. By giving the holding member a function of radiating heat generated by the light source, it is possible to prevent the light emission efficiency and life of the light source from being adversely affected. By making the light guide plate a polygonal column, the light exit surface can be made flat.

  In addition, the lamp device of the present invention can be mounted on a straight tube fluorescent lamp fixture by providing a base having the same shape as the straight tube fluorescent lamp at both longitudinal ends of the light source device. In addition, it is possible to attach to the socket for a light bulb by providing a light bulb base for supplying power to the drive circuit for driving the light source device. A compact lamp device can be realized by integrally configuring the housing for housing the drive circuit and the bulb base. In addition, power can be directly supplied from the ceiling by providing the drive circuit with a ceiling mounting member for supplying power from the ceiling.

  Furthermore, since a thin light source device can be obtained according to the present invention, it can be used as a space-saving light source. For example, it can be used in an environment or place where a fluorescent lamp or the like cannot be attached so far, including use as an alternative light source where a fluorescent lamp is conventionally used.

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.
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 26. . The light guide plate 3 is accommodated 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 surface 28 facing the side surface 26 of the light guide plate 3 is provided with an irregular reflection mechanism (not shown) 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 diffused reflection mechanism (not shown) disposed on each part of the surface 28 of the light guide plate and is emitted from the side surface 26 of the light guide plate 3. This principle will be described later.

  The light guide plate 3 of this example is a rectangular column having a rectangular cross section as shown in the figure, but may be a polygonal column having a cross section other than this. The length L of the side surface 26 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 of the end face 26 of the light guide plate, and also refers to both the thickness and width of the light emitting portion 27 of the LED 1 (light source). As shown in FIG. 2, the width of the end face 26 of the light guide plate is W, the thickness is T, the width of the light emitting portion 27 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 portion 27 of the LED 1 means that W> w and T> t.

  FIGS. 9A to 9C are diagrams for explaining the size of the light emitting unit 27 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 referred to as the light emitting portion 27 here. FIG. 9A shows the size (width w, thickness t) of the light emitting unit 27 in the case of one LED. FIG. 9B shows the size of the light emitting unit 27 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 27. FIG. 9C shows a case where a total of four LEDs are arranged, two vertically and two horizontally. 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 27. Even when the number of LEDs 1 increases, the width and thickness are determined in this manner. For example, in the case of a high power LED, the light emitting unit 27 is often configured with a diameter of about 4 to 5 mm. This is because the LED element to be used is about 1 mm square, and a distance of about 1 mm around the LED element is required as a region for extending a wire for energizing the LED element, and stress is applied to the wire. As the distance not given, a distance of about 1 mm is provided, and an interface sealed with a transparent resin or a wall surface for sealing the transparent resin is configured. For this reason, the diameter of the light emission part 27 of LED1 will be (phi) 4-5 mm. Therefore, the thickness of the light guide plate needs to be 4 mm or more in accordance with the light emitting unit 27.

  As described above, the surface 28 facing the side surface 26 of the light guide plate 3 is provided with 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 surface 28 facing the side surface 26 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.

  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, since the light reflected in the direction of the side surface 26 facing the surface 28 on which the silk printing 10 is applied is incident on the side surface 26 at a critical angle or less, total reflection does not occur and the light is emitted from the side surface 26. Become. 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 face 26 as described above, and the light hitting the non-printed part is maintained in total reflection, and the light is guided in the direction farther from the light source. The Rukoto. 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 hits the groove, the reflection angle changes and the light is emitted from the side surface 26. 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 embodiment of a lamp device using the light source device according to the present invention. In this lamp device, caps 12 and 13 having the same shape as a straight tube fluorescent lamp are arranged at both ends in the longitudinal direction of the light source device according to the present invention. The bases 12 and 13 are provided with base terminals having the same shape as the straight tube fluorescent lamp. By matching the overall length of the light source device shown in FIG. 6 with the dimensions of the straight tube fluorescent lamp, the light source device can be attached to an existing lighting device for a straight tube fluorescent lamp.

  FIG. 7 is a view showing another embodiment of a lamp device using the light source device according to the present invention. The lamp device includes four light source devices 14, 15, 16, and 17 according to the present invention, and includes a drive circuit 6 that drives these light source devices and a light bulb base 18 that supplies power to the drive circuit 6. Is. In this example, the drive circuit 6 is housed in a housing 19, and the housing 19 and the light bulb base 18 are integrally configured. The light bulb cap 18 can be inserted into a light bulb socket. The arms 20, 21, 22, and 23 have both a mechanism for fixing each of the light source devices 14 to 17 to the housing 19 and a mechanism for supplying power. The voltage fed from the base 18 is supplied to the light source devices 14 to 17 through the drive circuit 6 and the arms 20 to 23 housed in the housing 19, whereby the light source device emits light. With this configuration, it can be used as a light source device instead of a light bulb. Further, if the arms 20 to 23 are configured to move, the light source device realized in the present embodiment can vary the light distribution characteristics. In this example, the number of light source devices is four. However, the present invention is not limited to this, and at least one light source device may be used.

  FIG. 8 is a diagram showing another embodiment of a lamp device using the light source device according to the present invention. The lamp device includes four light source devices 14, 15, 16, and 17 according to the present invention, a drive circuit 6 that drives these light source devices, and a power supply to the drive circuit 6 via a cord 32 from the ceiling. A ceiling mounting member (sealing tap) 33 is provided. The ceiling mounting ceiling tap 33 is accommodated in the case 24. A voltage is supplied from a power source (not shown) to the light source devices 14 to 17 through the sealing tap 33 housed in the case 24, the cord 32, the drive circuit 6 housed in the housing 19, and the arms 20 to 23. The light source device emits light. By setting it as this structure, it becomes possible to implement | achieve the thing equivalent to a hanging type lighting fixture. Further, if the arms 20 to 23 are configured to move, the lamp device realized in this embodiment can vary the light distribution characteristics. In this example, the number of light source devices is four. However, the present invention is not limited to this, and at least one light source device may be used.

  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 order to increase the light utilization efficiency, the light incident efficiency can be increased by making the light emitting area of the light source smaller than the area of the light incident portion. In order to reduce the area of the light emitting portion of the light source and to ensure the brightness of the light emitted from the light source device, it is desirable to use a light source having a larger light emission amount. In recent years, there are LED devices capable of supplying a large amount of power called high-power LEDs, which can be realized by using them. However, a light source that emits a large amount of light with a small light emitting area has a large amount of heat generated by the light source itself. Therefore, a material that holds the light source, such as metal, has a high heat dissipation property. It is necessary to dissipate heat.

  Further, in recent years, a light guide plate used in a general liquid crystal backlight or the like is thin, and if used in the present invention, even if a light source having a light emitting area smaller than the light incident surface area of the light guide plate is used, The light source becomes thicker in the thickness direction. Therefore, it is necessary to maintain the relationship between the light incident area of the light guide plate and the light emitting area of the light source, and at the same time, to reduce the size of the light source light emitting part in both the thickness and width dimensions than the light guide plate incident area. With such a configuration, it is possible to achieve a linear light source with improved brightness and color uniformity, in which the light emitting portion is miniaturized.

  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 one Example of the lamp device using the light source device which concerns on this invention. It is a figure which shows the other Example of the lamp device using the light source device which concerns on this invention. It is a figure which shows the other Example of the lamp device using 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.

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 , 12, 13 ... base, 14, 15, 16, 17 ... light source device, 18 ... light bulb base, 19 ... housing, 20, 21, 22, 23 ... arm, 24 ... case

Claims (11)

  A light source; a holding member for holding the light source; and a light guide plate for introducing light from the light source from an end surface and emitting the light from the side surface, wherein the length of the side surface is the length of the end surface. A diffuse reflection mechanism that is longer than the width and has a size of the end surface larger than the size of the light emitting portion of the light source, and is arranged on the surface facing the side surface from coarse to dense as the distance from the end surface increases. A light source device.   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 includes a plurality of light emitting diodes, and the plurality of light emitting diodes are light emitting diodes having a plurality of different emission wavelengths.   The light source device according to claim 2, wherein a thickness of the light guide plate is 4 mm or more.   The light source device according to claim 1, wherein the holding member has a function of radiating heat generated by the light source.   The light source device according to claim 1, wherein the light guide plate is a polygonal column.   A lamp device comprising: the light source device according to any one of claims 1 to 7; and a base having the same shape as a straight tube fluorescent lamp disposed at both longitudinal ends of the light source device.   8. A lamp device comprising: at least one light source device according to claim 1; a drive circuit that drives the light source device; and a light bulb base for supplying power to the drive circuit.   The lamp device according to claim 9, further comprising a housing that accommodates the drive circuit, wherein the housing and the bulb base are configured integrally.   It has at least one light source device according to any one of claims 1 to 7, a drive circuit for driving the light source device, and a ceiling mounting member for supplying power to the drive circuit from the ceiling. Lamp device to do.

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