JP4535835B2 - Illumination device and projection display device - Google Patents

Description

  The present invention relates to an illumination device using a point light source typified by a light emitting diode as a light source, and a projection display device including the illumination device.

  The projection display device forms image light by illuminating a light valve as a display device with light output from the illumination device, and projects the formed image light toward a screen. Conventionally, high-pressure discharge lamps such as high-pressure mercury lamps, metal halide lamps, and xenon lamps have been used as light sources for lighting devices. These high-pressure discharge lamps emit high-intensity white light, and are desirable light sources from the viewpoint of displaying a bright image. However, new light sources are being sought in order to realize miniaturization and low power consumption of the projection display device, and light emitting diodes are attracting attention as potential candidates. More specifically, blue and green light emitting diodes have been remarkably developed in recent years. When combined with red light emitting diodes that are already capable of emitting light with high efficiency, red (R), green (G), It is considered that the three primary colors of blue (B) are aligned and can be used as the light source of the illumination device.

However, each light emitting diode has a small amount of emitted light, and in order to be used as a light source of an illuminating device, a large number of light emitting diodes must be arranged to increase the amount of luminous flux as a whole light source. What is important at this time is to arrange as many light emitting diodes as possible and to efficiently irradiate the light valve with a large amount of light emitted from these many light emitting diodes. Therefore, Patent Document 1 discloses a light source device as shown in FIG. The light source device shown in FIG. 7 includes a hollow rod-shaped member 400 and a large number of light-emitting diodes 402 arranged on the inner surface 401 of the rod-shaped member 400 along the longitudinal direction of the member 400. Furthermore, the inner surface 401 of the rod-shaped member 400 on which the light emitting diodes 402 are disposed is a reflecting surface. In Patent Document 1, a light beam emitted from each light emitting diode 402 travels toward one end 403 in the longitudinal direction of the rod-shaped member 400 while being reflected by the inner surface (reflection surface) 401 of the rod-shaped member 400, and finally. It is stated that the light is emitted from the one end 403. It is also stated that a light source device with high luminance and high light collection efficiency can be realized by making the rod-shaped member 400 thinner to reduce the area of the light exit surface.
JP 2004-63335 A

  However, the light source device disclosed in Patent Document 1 has the following problems. That is, the light emitted from the light emitting diode is divergent light. Therefore, the light emitting component that is closer to the light emitting surface of each light emitting diode 402 shown in FIG. 7 is incident on the inner surface 401 opposite to the installation surface at a smaller incident angle. Here, since the opposing inner surfaces 401 of the rod-shaped member 400 are parallel to each other, the incident / exit angle of light traveling in the longitudinal direction of the rod-shaped member 400 while repeating reflection between the opposing inner surfaces 401 is the progression of the light. Does not change inside. Therefore, the angle of light emitted from one end 403 of the rod-shaped member 400 becomes larger as the light emitting component is perpendicular to the light emitting surface of the light emitting diode 402.

  However, from the viewpoint of light utilization efficiency and image quality, it is desirable to irradiate the light valve with light having as small an angle component as possible, and ideally illuminate the light valve with parallel light. For example, when a light bubble (liquid crystal panel) is illuminated with light having a large angle component, there is a problem that the contrast of the display image is lowered due to the influence of the viewing angle characteristics of the liquid crystal. Furthermore, the size of the lens for finally projecting the light that has passed through the light valve onto the screen is increased, which increases the size and cost of the projection display device.

  The present invention has been made in view of the above problems, and provides an illuminating device capable of illuminating a light valve with light having as small an angle component as possible while securing a sufficient amount of luminous flux by providing as many point light sources as possible. The purpose is to provide.

  The illumination device of the present invention includes a light guide member including an exit end face, a first entrance face and a second entrance face having sides common to the exit end face, the first entrance face, and the first entrance face. A plurality of point light sources arranged on each of the two incident surfaces, and a side common to the first incident surface and the output end surface is a side common to the second incident surface and the output end surface; In contrast, the first incident surface and the second incident surface are characterized in that the first incident surface and the second incident surface are inclined so that the distance between the first incident surface and the second incident surface increases as they approach the emission end surface.

  Therefore, the light guide member constituting the illumination device of the present invention has two incident surfaces, and more light sources can be arranged around the light guide member while avoiding an increase in size of the light guide member. Furthermore, if the area ratio between the entrance surface and the exit end surface is increased, the light collection efficiency can be further increased. Moreover, since the space | interval of the 1st entrance plane of a light guide member and a 2nd entrance plane has spread as it approaches an output end surface, it injects in a light guide member and advances toward an output end surface, repeating reflection. The reflection angle of light is gradually relaxed in the process of traveling. Therefore, light having a relatively small angle component is emitted from the end of the emission surface.

  According to the present invention, an illumination device that can illuminate an illumination target with illumination light having high luminance and a small angle component, and a projection display device including such an illumination device are realized.

(Embodiment 1)
Hereinafter, an example of an embodiment of the illumination device of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic side view showing the configuration of the illumination device of this example. FIG. 2 is a schematic perspective view showing the shape of the light guide member constituting the illumination device of this example.

  As shown in FIG. 1, the illumination device of this example includes a light guide member 101 and a plurality of point light sources (light emitting diodes 102 and 103). The light guide member 101 includes a rectangular emission end face 104, a first incident face 105 and a second incident face 106 that are continuous with a pair of opposite sides of the emission end face 104, and another pair of sides of the emission end face 104. Each of the two side surfaces. Further, the first incident surface 105 and the second incident surface 106 are larger in area than the exit surface 104 and are inclined so as to gradually approach each other as they move away from the exit end surface 104, and finally intersect. In other words, the distance between the first incident surface 105 and the second incident surface 106 increases as it approaches the emission end surface 104. That is, the light guide member 101 has a substantially wedge-shaped appearance as a whole. Note that the shape of the emission end face 104 is preferably similar to that of an illumination target (not shown) to which the light emitted from the emission end face 104 is irradiated.

  The material of the light guide member 101 is not particularly limited, and the light guide member 101 can be manufactured using optical resin, optical glass, translucent ceramics, or the like. However, in view of ease of processing, an optical resin is suitable as a material for the light guide member 101. An example of the optical resin that is the material of the light guide member 101 is a light scattering light guide polymer. The light-scattering light-guiding polymer is a resin material such as PMMA (polymethyl methacrylate) or PC (polycarbonate), and a particulate material having a refractive index different from that of the resin material, for example, a silicon resin powder. Kneaded at a predetermined volume fraction. This light-scattering light-guiding polymer does not attenuate light by the multiple scattering action obtained by controlling the relative refractive index of a micro-inhomogeneous structure without light absorption and the particle size of the particulate matter. , And can be emitted uniformly in a specific direction.

  A plurality of light emitting diodes 102 are arranged in an array on the first incident surface 105 of the light guide member 101, and a plurality of light emitting diodes 103 are arranged in an array on the second incident end surface 106. The light emitting diodes 102 and 103 are common in that a light emitting element and a dome-shaped resin having a lens action are integrated. However, the light emitting diode 102 disposed on the first incident surface 105 is a red light emitting diode that emits red light. On the other hand, some of the light emitting diodes 103 disposed on the second incident surface 106 are green light emitting diodes 103g that emit green light, and the other few are blue light emitting diodes 103b that emit blue light. . A thin film 110 having a characteristic of reflecting green and blue light is formed on the first incident surface 105 where the red light emitting diode 102 is disposed, and the green light emitting diode 103g and the blue light emitting diode 103b are disposed. A thin film 111 having a characteristic of reflecting red light is formed on the second incident surface 106. But the relationship between the 1st entrance plane 105 and the 2nd entrance plane 106, and the kind of light emitting diodes 102 and 103 arrange | positioned there is not limited to the said relationship. For example, the red light emitting diode 102 and the blue light emitting diode 103b may be disposed on the first incident surface 105, and the green light emitting diode 103g may be disposed on the second incident surface 106. In this case, a thin film having characteristics of transmitting red and blue light and reflecting green light is formed on the first incident surface 105. On the other hand, a thin film having characteristics of transmitting green light and reflecting red and blue light is formed on the second incident surface 106. In any case, the light emitting diodes 102 and 103 are arranged such that their optical axes form a predetermined angle with respect to the corresponding incident surfaces 102 and 103. This is because the light-emitting diodes 102 and 103 having the above-described structure have no divergence of the emitted light, although the divergence angle of the emitted light is controlled to some extent by the resin having a lens action.

  Next, the operation of the illumination device of this example will be described with reference to FIG. The red light 131 emitted from the red light emitting diode 102 enters the light guide member 101 from the first incident surface 105, and most of the red light 131 is totally reflected by the second incident surface 106. Here, although there is a light component that does not cause total reflection on the second incident surface 106, this light component is reflected by the thin film 111 formed on the second incident surface 106. That is, substantially all of the red light 131 emitted from the red light emitting diode 102 is reflected by the second incident surface 106, and thereafter between the first incident surface 105 and the second incident surface 106. The light reaches the exit end face 104 while repeating total reflection, and exits from the exit end face 104. What is important here is that the light component reflected by the thin film 111 formed on the second incident surface 106 is not changed between the first incident surface 105 and the second incident surface 106 thereafter. It is to repeat reflection. This is because the first incident surface 105 and the second incident surface 106 are inclined so that the distance between the first incident surface 105 and the second incident surface 106 increases as they approach the emission end surface 104. This is because the incident angle on the second incident surface 106) increases with each reflection.

  On the other hand, the green light 132 emitted from the green light emitting diode 103 g and the blue light 133 emitted from the blue light emitting diode 103 b enter the light guide member 101 from the second incident surface 106, and are transmitted by the first incident surface 105. Most of them are totally reflected. Again, there is a light component that does not cause total reflection at the first incident surface 105. However, this light component is reflected by the thin film 110 formed on the first incident surface 105. That is, substantially all of the green light 132 emitted from the green light emitting diode 103 g and the blue light 133 emitted from the blue light emitting diode 103 b are reflected by the first incident surface 105, and thereafter the second incident surface 106. The light reaches the exit end face 104 while repeating total reflection between the first entrance face 105 and the first entrance face 105, and exits from the exit end face 104. Here again, the light component once reflected by the thin film 110 formed on the first incident surface 105 repeats total reflection between the second incident surface 106 and the first incident surface 105 thereafter. The reason is the same as above.

  As described above, the red (R), green (G), and blue (B) color lights 131, 132, and 133 emitted from the light emitting diodes 102 and 103 are efficiently emitted from the emission end face 104 of the light guide member 101. Is done. Further, the angles of the colored lights 131, 132, 133 are gradually relaxed in the process of traveling through the light guide member 1 while repeating total reflection. This means that the angle component of the light emitted from the emission end face 104 is relatively small and is incident at a relatively shallow angle with respect to the illumination target.

  In addition, if the lighting timing of the light emitting diodes 102 and 103 is controlled, the color of light emitted from the emission end face 104 of the light guide member 101 is repeatedly changed, for example, in the order of RGBBBRGB. It is obvious from the above explanation that this is possible.

  Next, an example of a projection display device using the illumination device of this example will be described with reference to FIG. The projection display device described here is a single-plate liquid crystal projector having a single light valve (liquid crystal panel), and FIG. 4 is a schematic diagram showing a schematic structure of the liquid crystal projector.

  This liquid crystal projector includes a lens 151, a liquid crystal panel 152, and a projection lens 153 in addition to the illumination device 150 of this example. However, the lens 151 is disposed for the purpose of efficiently irradiating the liquid crystal panel 152 with light (illumination light) emitted from the illumination device 150, and is not necessarily an essential configuration. Further, a polarizer and an analyzer are arranged before and after the liquid crystal panel 152, but the illustration is omitted.

  The lighting timing of the light emitting diodes 102 and 103 of the illumination device 150 is controlled by a control unit (not shown), and illumination light is repeatedly emitted in the order of R-G-B-R. The illumination light emitted from the illumination device 150 is applied to the liquid crystal panel 152 that is driven in synchronization with the emission timing of the illumination light by the illumination device 150, and the image formed on the liquid crystal panel 152 passes through the projection lens 153. Is enlarged and projected on a screen (not shown).

  Since this liquid crystal projector uses a single transmissive liquid crystal panel 152 as a light valve, the projection lens 153 and the liquid crystal panel 152 can be disposed close to each other, and the entire apparatus is very small. In addition, there is an advantage that a full color image can be displayed with an extremely simple structure.

Needless to say, in addition to the configuration shown in FIG. 4, an optical system, a control system, a drive system, and the like necessary for realizing a function as a liquid crystal projector are provided. However, optical systems, control systems, drive systems, and the like that are not shown in the figure are substantially the same as those included in existing liquid crystal projectors, and thus description thereof is omitted.
(Embodiment 2)
Hereinafter, another example of the embodiment of the illumination device of the present invention will be described with reference to FIG. The basic configuration of the illumination device of this example is the same as that of the illumination device shown in FIG. Therefore, the same components as those already described in the first embodiment are denoted by the same reference numerals in FIG.

  The illumination device of this example is different from the illumination device shown in FIG. 1 in that the thin films 110 and 111 shown in FIG. 1 are not directly formed on the first incident surface 105 and the second incident surface 106 of the light guide member 101. Is a point. Specifically, a glass substrate 201 on which a thin film having the same characteristics as the thin film 110 is deposited is disposed between the first incident surface 105 and the red light emitting diode 102. In addition, a glass substrate 202 on which a thin film having the same characteristics as the thin film 111 is deposited is disposed between the second incident surface 106 and the green light emitting diode 103g and the blue light emitting diode 103b. However, the behavior of light emitted from the light emitting diodes 102 and 103 is the same as the behavior described in the first embodiment.

Although gaps are provided between the glass substrates 201 and 202 and the incident surfaces 105 and 106 shown in FIG. 5, the glass substrates 201 and 202 and the incident surfaces 105 and 106 may be in close contact with each other. The glass substrates 201 and 202 on which the thin film is formed can be easily manufactured using a commercially available dichroic mirror. If the shape and dimensions match, a commercially available dichroic mirror can be used as it is. Note that the illumination device 150 shown in FIG. 4 can be replaced by the illumination device of this example.
(Embodiment 3)
Hereinafter, still another example of the embodiment of the illumination device of the present invention will be described with reference to FIG. The basic configuration of the illumination device of this example is the same as that of the illumination device shown in FIG. Therefore, the same components as those already described in the first embodiment are denoted by the same reference numerals in FIG.

  The illumination device of this example is different from the illumination device shown in FIG. 1 in that an optical element is interposed between the light emitting diodes 102 and 103 and the first incident surface 105 and the second incident surface 106. is there. Specifically, the rod integrator 300 is disposed between the light emitting diode 102 and the first incident surface 105 and between the light emitting diode 103 and the second incident surface 106. The rod integrator 300 is an elongated columnar optical glass member or an optical resin member. Light incident from one end surface 301 in the longitudinal direction travels through the rod integrator 300 while repeating total reflection, and exits from the other end surface 302. To do. In the illumination device of this example, the rod integrator 300 is provided for each of the light emitting diodes 102 and 103, and light emitted from each of the light emitting diodes 102 and 103 enters from the end face 301 of the corresponding rod integrator 300, and the rod integrator 300 The light emitted from the other end surface 302 of 300 is disposed so as to enter the first incident surface 105 or the second incident surface 106 of the light guide member 101. By the action of the rod integrator 300, the divergence of light emitted from the light emitting diodes 102 and 103 is further suppressed, and the total reflection efficiency after entering the light guide member 101 is improved. From such a viewpoint, it is desirable that the shape of the rod integrator 300 is as shown in FIG. That is, it is desirable that the taper shape gradually increases from the incident-side end face 301 toward the outgoing-side end face 302. However, the above action can also be obtained by a rod integrator having a uniform thickness in the light traveling direction. Here, “tapered shape is desirable” means that if the shape is tapered, the above-described effect becomes more remarkable, and does not mean that shapes other than the tapered shape are excluded. Further, even if a convex lens is arranged at the above position instead of the rod integrator 300 shown in FIG. Note that the illumination device 150 shown in FIG. 4 can be replaced by the illumination device of this example.

It is a typical side view which shows an example of embodiment of the illuminating device of this invention. It is a typical perspective view which shows the shape of the light guide member of FIG. It is a schematic diagram which shows the effect | action of the illuminating device of FIG. It is a schematic diagram which shows the structure of the projection type display apparatus using the illuminating device of FIG. It is a typical side view which shows the other example of embodiment of the illuminating device of this invention. It is a typical side view which shows the further another example of embodiment of the illuminating device of this invention. It is a figure which shows an example of the conventional light source device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Light guide member 102, 103 Light emitting diode 104 Output end surface 105 1st incident surface 106 2nd incident surface 110, 111 Thin film 131 Red light 132 Green light 133 Blue light 201, 202 Glass substrate 300 Rod integrator

Claims (5)

A light guide member having a first incident surface and a second incident surface that have an emission end surface, a side common to the side forming the emission end surface, and facing each other;
A plurality of point light sources disposed on each of the first incident surface and the second incident surface;
A first wavelength selection film provided between the first incident surface and the point light source disposed on the first incident surface;
A second wavelength selection film provided between the second incident surface and the point light source disposed on the second incident surface;
The side that the first incident surface shares with the exit end surface is different from the side that the second incident surface shares with the exit end surface, and the first entrance surface and the second entrance surface are different from each other. , Gradually approaching as it gets away from the exit end face, and is inclined so as to finally intersect,
The point light source is disposed obliquely with respect to each of the first incident surface and the second incident surface so that an optical axis thereof is inclined toward the emission end face side.
The first wavelength selection film transmits light emitted from the point light source disposed on the first incident surface and is emitted from the point light source disposed on the second incident surface. Has the property of reflecting light,
The second wavelength selection film transmits light emitted from the point light source disposed on the second incident surface and is emitted from the point light source disposed on the first incident surface. An illumination device having a characteristic of reflecting light.   The lighting device according to claim 1, wherein the first wavelength selection film is formed on a surface of the first incident surface, and the second wavelength selection film is formed on a surface of the second incident surface. A translucent member on which the first wavelength selection film is formed is interposed between the first incident surface and the point light source disposed on the first incident surface;
2. The translucent member on which the second wavelength selection film is formed is interposed between the second incident surface and the point light source disposed on the second incident surface. Lighting device.   The point light source disposed on the first incident surface is a red light emitting diode, and the point light sources disposed on the second incident surface are a green light emitting diode and a blue light emitting diode. Item 4. The lighting device according to any one of Items 3 to 4.   The illumination device according to any one of claims 1 to 4, a light valve irradiated with illumination light emitted from the illumination device, and a projection for enlarging an image formed on the light valve on a screen A projection display device having at least a lens.

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