JP4434120B2 - Light source device - Google Patents

Description

  The present invention relates to a light source device. In particular, the present invention relates to a light source device used for a backlight of a display device.

  Conventionally, a planar light source using a light guide plate has been widely used as a backlight of a display device using light. For example, Patent Document 1 discloses a display device that obtains planar light by incorporating a light guide plate in an indicator portion of a vehicle and guiding light from an LED light source to the light guide plate. In this display device, a reflection portion is provided around the light guide so that the entire surface on the display side emits light uniformly. On the other hand, Patent Document 2 discloses a planar light-emitting device that generates a high-luminance planar light by providing a light diffusing layer on a transparent light guide and forming irregularities on the surface of the light diffusing layer. .

JP 2000-28397A Japanese Patent No. 3071247

In the backlight of the conventional display device, the entire display side surface of the light guide plate emits light uniformly. However, depending on the display mode, only light emitted from a part of the display-side surface may be used as the backlight. In that case, no light emitted from other parts is used and is wasted.
On the other hand, in recent years, there is a demand for higher brightness of the light source device. In order to cause the LED device to emit light with high luminance, it is conceivable to increase the amount of current flowing to the LED device. However, increasing the amount of current flowing to the LED device increases the amount of heat generation, which may lead to a decrease in drive stability and reliability of the LED device. Further, LED devices are densely arranged to uniformly emit light from the light emitting surface of the light guide. If the LED devices are arranged densely, it is difficult for the heat generated from the individual LED devices to escape, and special heat dissipation measures may be required. In particular, if the amount of heat generation increases due to the high-luminance emission of the LED device, the necessity for heat dissipation measures becomes more prominent.
Accordingly, an object of the present invention is to make effective use of light and to emit necessary portions with high luminance. Another object is to provide a light source device with high heat dissipation.

In order to achieve the above object, the present invention provides a light source device shown below. That is,
An LED light source;
A light guide plate disposed on the light emission side of the LED light source, and a plurality of light diffuse reflections formed by performing a light diffusion reflection process on a light introduction surface facing the LED light source and a part on the back surface side A light guide plate, wherein the light diffuse reflection process is different for each light diffusion region,
A light source device in which a convex prism-like pattern is applied to a part of the plurality of light diffusion reflection regions and a convex lens-like pattern is applied to the other part .

In the light source device of the present invention, the light from the LED light source enters the light guide plate from the light introduction surface of the light guide plate and travels through the light guide plate. When the incident light reaches the light diffuse reflection area, it is diffusely reflected and emitted from the surface of the light guide plate. Here, since the plurality of light diffusion reflection areas are formed on a part of the back surface side of the light guide plate, the incident light is selectively diffusely reflected by the plurality of light diffusion reflection areas. Further, since the plurality of light diffusion reflection areas are subjected to different light diffusion reflection processing for each light diffusion reflection area, each of the plurality of light diffusion reflection areas diffuses and reflects light in a different manner. As described above, the incident light is reflected and diffused, so that the incident light is emitted from the light emitting surface of the light guide plate in a different manner, thereby providing a light emitting manner with high design. Further, since the light is concentrated on the shape to be displayed, the luminance is also improved. Therefore, the required luminance can be obtained with a smaller amount of light. Thereby, since it becomes possible to reduce the number of LED apparatuses used for an LED light source, manufacturing cost can be reduced. Further, if the number of LED devices to be used is reduced, the heat dissipation is improved as compared with the case where many LED devices are used. Furthermore, if the number of LED devices to be used is reduced, it is not necessary to arrange the LED devices more densely than necessary, which contributes to improvement in heat dissipation.
A convex lens-shaped light reflection / diffusion pattern is formed on a part of the back surface of the light guide plate to form a first light diffusion / reflection region, and a convex prism-shaped light reflection / diffusion pattern is formed on the other part of the back surface of the light guide plate. A second light diffuse reflection region is formed. In general, the convex prism shape has a narrower directivity angle of reflected light than the convex lens shape. For this reason, the second light diffuse reflection region has a higher forward luminance than the first light diffuse reflection region and is observed brightly. On the other hand, the first light diffuse reflection region is observed dark because the front luminance is lower than that of the second light diffuse reflection region, but less uneven luminance is observed. Thereby, since the 1st light diffuse reflection area and the 2nd light diffuse reflection area are displayed in a different mode, there is high design nature. When the light source device of the present invention is used as an indicator for a vehicle, for example, an information display that displays fuel consumption, temperature, timepiece, remaining fuel, mileage, etc. is emitted by a convex lens-like light reflection / diffusion pattern, and a convex prism is displayed. Meter numbers, meter hands, etc. are displayed by the light reflection diffusion pattern. As a result, a portion that is highly necessary for the driver to view while traveling is displayed brighter and visibility is increased.

Hereafter, the component in the light source device of this invention is demonstrated in detail. (LED light source) LED is used as a light source of the light source device of the present invention. The LED light source includes an LED device, and irradiates the light to a light guide plate described later. The type of the LED device is not particularly limited, and a shell type, a surface mount type, or the like can be adopted. Moreover, you may use the LED light source provided with the some LED apparatus as a light source of this invention. The plurality of LED devices may be of the same type or may include different types of LED devices. For example, an arrayed LED light source in which LED devices are linearly arranged can be used. In the case of using an LED light source including a plurality of LED devices, it is preferable to determine the arrangement of the LED devices in consideration of the arrangement of light diffusion reflection areas of the light guide plate described later. Specifically, the plurality of LED devices are arranged such that each optical axis of the plurality of LED light sources passes through the light guide part located in the front of any one of the plurality of light diffusion reflection regions or the vicinity thereof in the light guide plate. It is preferable to arrange. According to such an arrangement, the light of the LED device efficiently reaches the light diffuse reflection area and is emitted from the light emitting surface of the light guide plate, so that the light use efficiency is improved. Furthermore, in the light guide plate, it is preferable that the LED device is arranged so that the optical axis of the LED light source passes through the light guide portion located in front of each of the plurality of light diffusion reflection regions or in the vicinity thereof. This is because the light of the LED device can be further concentrated on the light diffuse reflection region, and the light utilization efficiency is further improved.

(Light Guide Plate) The light guide plate is made of a light transmissive material. Transparent synthetic resins such as acrylic resin and polycarbonate resin, and transparent inorganic materials such as glass can be used as the light guide plate material. The light guide plate has a substantially flat plate shape, and one end surface of the light guide plate can be a light introduction surface on which light from the light source is incident. In addition, it is good also considering the some end surface of a flat light-guide plate as a light introduction surface.

A plurality of light diffusing / reflecting areas subjected to different light reflecting / diffusing processes for each light reflecting / diffusing area are formed on the rear surface side (the surface opposite to the light emitting side) of the light guide plate. Examples of the light diffuse reflection treatment include formation of a light diffuse reflection pattern, rough surface treatment such as embossing and blasting, formation of a light reflection diffusion layer by printing light reflection diffusible ink and applying a light reflection diffusion tape, etc. Can be adopted. The “light diffuse reflection pattern” in the present specification refers to a set of light diffuse reflection shapes. Examples of the light diffuse reflection shape include a convex lens shape, a convex prism shape, and a diffusion dot shape.
In this specification, “perform different light diffusion treatment” means, for example, forming a different light diffusion reflection pattern or forming a light diffusion reflection pattern in a part and roughing the other part. It refers to applying. By performing different light reflection / diffusion treatments, the light is diffused and reflected in different modes, so that it is observed in different modes, and the design is improved. Note that areas that are subjected to the same light diffuse reflection process are regarded as one light diffuse reflection area even if they are not continuous. That is, for example, when the same light diffusion treatment is performed on a plurality of locations on the back surface of the light guide, these are collectively regarded as one light diffuse reflection region.

As a preferred embodiment in which different light diffuse reflection treatments are applied to the two regions, a first light diffuse reflection region is formed by applying a convex lens-like light reflection diffusion pattern to a part of the back surface of the light guide plate, and the back surface of the light guide plate It is possible to form a second light diffusing / reflecting region by applying a convex prism-like light reflecting / diffusing pattern to the other part. In general, the convex prism shape has a narrower directivity angle of reflected light than the convex lens shape. For this reason, the second light diffuse reflection region has a higher forward luminance than the first light diffuse reflection region and is observed brightly. On the other hand, the first light diffuse reflection region is observed dark because the front luminance is lower than that of the second light diffuse reflection region, but less uneven luminance is observed. Thereby, since the 1st light diffuse reflection area and the 2nd light diffuse reflection area are displayed in a different mode, there is high design nature. When the light source device of the present invention is used as an indicator for a vehicle, for example, an information display for displaying fuel consumption, temperature, clock, remaining fuel, mileage, and the like is emitted and displayed by a convex lens-like light reflection / diffusion pattern. Meter numbers, meter hands, etc. are displayed by the light reflection diffusion pattern. As a result, a portion that is highly necessary for the driver to view while traveling is displayed brighter and visibility is increased. When the meter's needle is lit and displayed, the meter's needle is made of a light guide material, and light with high brightness is introduced from the light reflecting diffusion pattern in the form of a convex prism from below the axis to brighten the meter's needle. Can be displayed.
The “different light diffuse reflection process” does not include a different light diffuse reflection pattern density. When the same light reflection / diffusion pattern is formed at different densities, the frequency of occurrence of uneven light emission increases as the pattern density progresses from a high part to a low part. When unevenness in light emission occurs, the visibility and design properties are lowered, which is not preferable.

As the shape of each light diffuse reflection region, a desired shape such as a character or a geometric shape can be adopted. For example, when used as an indicator in a vehicle compartment, the shape can be in line with the outer shape of the meter display unit. The plurality of light diffuse reflection regions may have different shapes, or the plurality of light diffuse reflection regions may include the same shape region.
Hereinafter, the present invention will be described in more detail with reference to examples.

The front view of the light source device 1 which is one Example of this invention is shown in FIG. As shown in FIG. 1, the light source device 1 is applied to an indicator panel in a driver's seat in a vehicle. The light source device 1 is installed inside a transparent cover 12 fitted in a cabinet 11 and includes a panel 13, a light guide plate 20, and a light source 30. The panel 13 is a thin plate made of a light-transmitting resin, and a black paint is applied so that various display parts (tachometer 40, speedometer 50, information display 60 and used gear display part 70) are left behind. Furthermore, characters of various display portions are printed. A light guide plate 20 is provided behind the panel 13. The light guide plate 20 has a flat plate shape. Further, a light source 30 is disposed on the lower end surface (light introduction surface) 20a side of the light guide plate 20. In addition, needles 81 and 82 made of a light guide material are provided at the center of the tachometer 40 and the speedometer 50.
FIG. 2 shows the light guide 20 and the light source 30 extracted. Further, a cross-sectional view taken along the line II of FIG. 2 is shown in FIG. As shown in FIG. 2, light diffuse reflection areas 41, 51, 61 and 71 are formed on the back surface 20 c side of the light guide plate 20. Among them, a convex prism pattern is formed in the light diffuse reflection areas 41, 51 and 71 as a light diffuse reflection pattern. On the other hand, a convex lens-like pattern is formed in the light diffuse reflection region 61 (see FIG. 3). The light source 30 is an arrayed LED light source, and nine LED devices 32 are linearly arranged on a base 31. The LED device is a surface-mounted LED chip, and includes a light distribution control lens on the light emission side. The light source 30 is installed so as to face the light introduction surface 20 a of the light guide plate 20. Further, as shown in FIG. 3, each LED device 32 is arranged so that the optical axis 33 of each LED device 32 passes through the light guide portion in front of the light diffusion reflection areas 41, 51, 61, 71.

  Next, the light emission mode of the light source device 1 will be described. In conjunction with the vehicle width lamp, power is supplied to the light source 30 and the LED device 32 emits light. The light from the LED device 32 is applied to the light introduction surface 20 a at the lower end of the light guide plate 20, enters the light guide plate 20, and travels through the light guide plate 20. As shown in FIG. 3, part of the incident light reaches the light diffusion reflection region 61, is diffusely reflected, and is emitted from the light emitting surface 20 b side of the light guide plate 20. On the other hand, another part of the incident light reaches the light diffuse reflection region 51, is diffusely reflected, and is emitted from the surface side of the light guide plate 20. Similarly, the light reaching the light diffuse reflection areas 41 and 71 is diffusely reflected and emitted from the surface side of the light guide plate 20. The light emitted from the front surface side of the light guide plate 20 travels from the various display units 40, 50, 60, 70 formed on the panel 13 in a punching manner to the vehicle interior side, and the various display units 40, 50, 60, 70. Is displayed. Further, part of the emitted light is incident on the needles 81 and 82 from the shafts of the needles 81 and 82, and is guided through the needles 81 and 82 to emit light from the needles 81 and 82.

  According to the light source device 1, the light incident on the light guide plate 20 is not provided on the back surface 20 c side of the light guide plate 20 because light diffuse reflection processing is not performed on portions other than the light diffuse reflection regions 41, 51, 61, 71. Are concentrated in the light diffuse reflection areas 41, 51, 61, 71, and are diffusely reflected there. That is, light can be selectively collected in the light diffuse reflection areas 41, 51, 61, 71. Thereby, incident light is emitted in substantially the same shape as the various display units 40, 50, 60, 70 as a backlight of the various display units 40, 50, 60, 70. As a result, compared to the case where incident light is emitted from the entire surface 20b of the light guide plate 20, light is not emitted from unnecessary regions, and the light utilization efficiency is improved. Furthermore, since incident light is concentrated on the various display units 40, 50, 60, and 70, the luminance of the emitted light in the various display units 40, 50, 60, and 70 is improved. Therefore, since the required luminance can be obtained even with a small amount of incident light, the number of LED devices 32 used for the light source 30 can be reduced, and the manufacturing cost can be reduced. In addition, since the number of LED devices 32 to be used is small, the heat dissipation characteristics are improved as compared with the case where the LED devices are densely arranged.

  Further, a convex prism-like pattern is formed in the light diffusion reflection areas 41, 51, 71 as a light reflection diffusion process, and a convex lens pattern is formed in the light diffusion reflection area 61 as a light reflection diffusion process. As a result, the light diffuse reflection areas 41, 51, 71 reflect light having a narrower directivity angle than the light diffuse reflection area 61 forward. Accordingly, the tachometer 40, the speedometer 50, the used gear display unit 70, and the hands 81 and 82 are displayed brighter than the information display 60. That is, the tachometer 40, the speedometer 50, the used gear display unit 70, the hands 81 and 82, and the information display 60 are displayed in different modes, and high design characteristics are achieved. Further, the visibility is improved by displaying the tachometer 40, the speedometer 50, the used gear display unit 70, and the hands 81 and 82 brighter than the information display 60. The light source 30 used in the light source device 1 is an array light source and uniformly introduces light from the lower surface 20 a of the light guide plate 20. Therefore, for a light guide plate having a light diffuse reflection region subjected to a light diffuse reflection process different from the light diffuse reflection regions 41, 61, 51, 71, or a light guide plate having a light diffuse reflection region arrangement different from that of the light guide plate 20. Can also be suitably used. As a result, the light source can be shared, and the manufacturing cost can be reduced.

FIG. 4 shows a front view of a light source device 100 according to another embodiment of the present invention. Further, the light guide plate 200 and the light source 300 of the light source device 100 are extracted and shown in FIG. In addition, the same code | symbol is attached | subjected to the member same as the light source device 1, and the description is abbreviate | omitted.
The light source device 100 includes a panel 130, a light guide plate 200, and a light source 300. A black paint is applied to the light transmissive panel 130, and a speedometer 500 and an information display 600 are formed in a punching manner. Near the center of the speedometer 500, a needle 810 made of a light guide material is provided. A light guide plate 200 is installed behind the panel 130. The light source 300 is disposed so as to face the lower end surface (light introduction surface 200a) of the light guide plate 200. On the back surface of the light guide plate 200, light diffuse reflection areas 510 and 610 are formed on which light diffuse reflection patterns having substantially the same shape as the speedometer 500 and the information display 600 are applied. Among them, a convex prism pattern is formed in the light diffuse reflection area 510 as a light diffuse reflection pattern, and a convex lens pattern is formed in the light diffuse reflection area 610. The light source 300 is an array LED light source, and six LED devices 320 are linearly arranged on the base 31. Further, the LED device 320 is disposed only directly below the light guide portion in front of the light diffuse reflection areas 510 and 610, and its optical axis passes through the light guide portion. Further, as shown in FIG. 5, each LED device 320 is arranged so that the optical axis 330 of each LED device 320 is positioned in the light guide portion in front of the light diffuse reflection areas 510 and 610.

  The light source device 100 also has the same effect as the light source device 1. That is, by concentrating light on the speedometer 500, the needle 810, and the information display 600, the light use efficiency is improved. Furthermore, by displaying the speedometer 500 and the needle 810 brighter than the information display 600, high designability is achieved and the visibility of the speedometer 500 and the needle 810 is improved. In addition, in the light source device 100, since the LED device 320 is disposed only directly under the light guide portion in front of the light diffuse reflection areas 510 and 610, the number of LED devices used can be further reduced. Thereby, the manufacturing cost can be further reduced. Further, since the number of LED devices used is reduced, the heat dissipation characteristics are improved as compared with the case where a large number of LED devices are used.

  The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.

  The light source device of the present invention can be applied to backlight light sources of various display units including a backlight light source of an indicator panel of a vehicle.

It is a front view of the indicator panel of the vehicle interior driver's seat to which the light source device 1 which is one Example of this invention is applied. 2 is a perspective view of a light guide plate 20 and a light source 30 of the light source device 1. FIG. It is the II sectional view taken on the line in FIG. It is a front view of the indicator panel of the vehicle interior driver's seat to which the light source device 100 which is the other Example of this invention is applied. 2 is a perspective view of a light guide plate 200 and a light source 300 of the light source device 100. FIG.

Explanation of symbols

1, 100 Light source device 20, 200 Light guide plate 30, 300 Light source 32, 320 LED device 40 Tachometer 50, 500 Speedometer 60, 600 Information display 70 Gear display unit 41, 51, 61, 71, 510, 610 Light reflection diffusion Area 81, 82, 810 needle

Claims (2)

An LED light source;
A light guide plate disposed on the light emission side of the LED light source, and a plurality of light diffuse reflections formed by performing a light diffusion reflection process on a light introduction surface facing the LED light source and a part on the back surface side A light guide plate, wherein the light diffuse reflection process is different for each light diffusion region,
A light source device in which a convex prism-like pattern is applied to a part of the plurality of light diffusion reflection regions and a convex lens-like pattern is applied to the other part .   The LED light source includes a plurality of LED devices, and each optical axis of the plurality of LED devices is a light guide plate portion located in front of one of the plurality of light diffusion reflection regions or the vicinity thereof in the light guide plate. The light source device according to claim 1, which passes through.

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