JP5047735B2 - Illumination device and image display device - Google Patents

Illumination device and image display device Download PDF

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JP5047735B2
JP5047735B2 JP2007223795A JP2007223795A JP5047735B2 JP 5047735 B2 JP5047735 B2 JP 5047735B2 JP 2007223795 A JP2007223795 A JP 2007223795A JP 2007223795 A JP2007223795 A JP 2007223795A JP 5047735 B2 JP5047735 B2 JP 5047735B2
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light
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rod lens
array
light source
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JP2009058594A (en
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洋 秋山
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株式会社リコー
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  The present invention relates to an illuminating device used for an image display device, and a portable device such as a small, lightweight, thin mobile phone, portable game machine, digital camera, electronic notebook, electronic book, and laptop computer equipped with the illuminating device. Alternatively, the present invention relates to an image display device such as a projection display device that can be incorporated in a small device.

2. Description of the Related Art Conventionally, there is known a projection type display device that synthesizes image light by a light valve such as a liquid crystal light modulation element and enlarges and projects the synthesized image light on a screen through a projection optical system including a projection lens.
FIG. 13 shows a conventional projection type image display device shown in FIG. In this projection type image display device, the light emitted from the light source 110 is separated into three colors by the dichroic mirrors 113 and 114, and the light of each color is sent to three liquid crystal light valves (light modulators) 122, 123, and 124. After being used and modulated, they are combined again by the dichroic prism 125 and projected onto the screen 127 by the projection optical system 126. In the figure, 111 is a light emitting element, and 112 is a cover.
Therefore, a large number of optical components are required, and it has been difficult to reduce the size, weight, and thickness of the device.

  In order to solve this problem, the invention described in Patent Document 1 is emitted from each light source composed of light emitting diodes or electroluminescence elements that emit light of each color of red R, green G, and blue B. Each color light is condensed by a lens provided corresponding to each light source, and then guided to a rod lens by a light guide means to which four right-angle prisms are bonded, and each color emitted from the rod lens. Disclosed is a projection-type display device that includes one liquid crystal light valve (light modulation device) that modulates light and synthesizes an image, and a projection lens that enlarges and projects an image synthesized by the liquid crystal light valve onto a screen. (FIG. 1 of Patent Document 1 and the description thereof).

  In Patent Document 2, three light sources that can emit red light (R), green light (G), and blue light (B), respectively, and the illuminance of each color light emitted from each light source are uniform. An inclined rod integrator for reducing the angle of dispersion and a low dispersion angle, a dichroic cube (dichroic prism) for synthesizing (optical path synthesis) each color light whose angle of dispersion is reduced by the inclined rod integrator, and a polarizing beam splitter An illumination optical system is disclosed.

  In Patent Documents 1 and 2 described above, adhesion between prisms (dichroic cubes, polarization beam splitters, etc.) used for optical path synthesis, adhesion between the prisms and other optical elements (rod integrators), There is no disclosure regarding the adhesion between the optical element and the holding member, and when an adhesive having a refractive index close to or high in refractive index is used, there is a problem in that light is dissipated and light utilization efficiency is lowered.

  In addition, the invention described in Patent Document 2 adopts a configuration in which red light is reflected by a dichroic film. Spectral characteristics of dichroic films used for optical path synthesis / separation of light beams having different wavelengths have an incident angle dependency. In general, the incident angle dependency of a light beam having a longer wavelength is larger than the incident angle dependency. The light beam with an angle is reflected by the light beam that is originally desired to be transmitted, resulting in a decrease in light use efficiency. There is a problem that it decreases.

JP 2002-189263 A JP 2006-337595 A

  The present invention has been made to solve the above-described problems, and has an illumination device that is excellent in light utilization efficiency and can be reduced in size, thickness, and weight with a simple configuration, and the illumination device. It is an object of the present invention to provide a small, thin and light projection type image display device.

In order to solve the above-described problems, the illumination device according to claim 1 is a light source including a semiconductor light-emitting device that emits light by selecting a plurality of light-emitting elements having different emission wavelengths according to colors, and light emission from the light source. A first surface that is made of a material that is transparent to light and has an area equal to or greater than the area of the light source; and a second surface that has an area larger than the first surface and faces the first surface; a rod lens array in which the rod lenses are arrayed with the optical path having an array of optical path synthesizing prism light emitted comprises a dichroic mirror for coupling from the second of each rod lens on the side of the rod lenses of the rod lens array An illumination device configured with a synthesis prism array, wherein the light source is disposed on the first surface side of each rod lens of the rod lens array, and the optical path synthesis prism The array dichroic wavelength light as the light source transmitted through a large number of times of dichroic mirror is arranged to be longer, the prism array has at least one total reflection prism, the optical path between the synthesis prism of the optical path synthesizing prism array Is adhered with an adhesive having a refractive index of 1.4 or less, and the side surface connecting the first surface and the second surface of the rod lens has a fine structure shorter than the wavelength of the light source. It is characterized by .
The invention of the lighting device according to claim 2, in claim 1, the side surface of the first surface and the rod lens connecting the second surface of the rod lens is to substantially reflect light emitted from the light source It is characterized by.
The invention of the lighting device according to claim 3, in claim 1 or claim 2, characterized in that disposed a polarizer on the second surface side of the rod lens array.
According to a fourth aspect of the present invention, there is provided the lighting device according to the third aspect , wherein the polarizer is a reflective polarizer.
According to a fifth aspect of the present invention, there is provided the lighting device according to the fourth aspect , wherein the polarizer is formed on the second surface of the rod lens array.
The invention of the illumination device according to claim 6 is characterized in that in any one of claims 1 to 5 , each rod lens of the rod lens array is integrally molded.
According to a seventh aspect of the present invention, there is provided the lighting device according to any one of the first to sixth aspects, wherein the light source is arranged on one substrate.
The invention of the lighting device according to claim 8 is characterized in that, in any one of claims 1 to 7 , the same electrode of the light source that emits the same color is connected.
The invention of the lighting device according to claim 9 is the surface connecting the first surface and the second surface of each rod lens of the rod lens array according to any one of claims 1 to 8. The side surface is a curved surface.
The invention of an image display device according to claim 10 is the illumination device according to any one of claims 1 to 9 and light modulation that modulates light emitted from the illumination device in accordance with image information. Means.
An image display device according to an eleventh aspect of the present invention is the illumination device according to any one of the first to ninth aspects, and light modulation that modulates light emitted from the illumination device in accordance with image information. And a lens for enlarging and projecting the modulated light.

According to the present invention, a light emitting device corresponding to each color light of a light source composed of a semiconductor light emitting device that emits a plurality of color lights is arranged on the first surface side of each rod lens for changing light distribution characteristics. A light source that emits long-wavelength colored light in descending order of the number of times it passes through a plurality of optical path synthesis films (dichroic mirrors) of the prism array when the light emitted from each rod lens enters the optical path synthesis prism array to synthesize the optical path The light loss due to the angle characteristics of the optical path synthesis film can be reduced, and an illumination device with high light utilization efficiency can be provided.

  The present inventors have studied the angle dependency of a dichroic film that has been conventionally used in order to produce a desired illumination device and image display device. The dichroic film used in the present invention can be formed by using, for example, a known material and forming, for example, multiple layers on a glass surface according to a known method such as vacuum deposition.

In FIG. 1A, the horizontal axis represents the wavelength (nm), the vertical axis represents the reflectivity (%) of the film, the angle dependence of the dichroic film that reflects blue light and transmits green and red light. Showing gender. FIG. 1B shows the angle dependency of a dichroic film that reflects red light and transmits green and blue light. Three arrows in the figure indicate the spectral range of LEDs (Light Emitting Diode) of three colors (three primary colors of light) of R (red), G (green), and B (blue) in order from the right (hereinafter referred to as red light). May be described as R, green light as G, and blue light as B). As shown in the figure, the film that reflects red light (FIG. 1B) has a larger amount of change in film characteristics with respect to the incident angle than the film that reflects blue light (FIG. 1A). Specifically, in the film in FIG. 1B, among the light rays in the green region that are originally desired to be transmitted, the light rays having an angle corresponding to +12 degrees at the wavelength λ = 560 nm are reflected. That is, the light loss due to the angle characteristics of the film is large and the light utilization efficiency is reduced. Thus, in the invention described in Patent Document 2 discussed in the background section, the number of times the light having a shorter wavelength passes through the dichroic mirror, such as the light having a shorter wavelength is transmitted twice and then enters the light valve. It can be said that there are many configurations. The dichroic film used in the present invention can be formed by using, for example, a known material and forming, for example, multiple layers on a glass surface according to a known method such as vacuum deposition. A commercially available dichroic filter or the like can also be used .

  In contrast, the present invention increases the number of times that light having a longer wavelength passes through the optical path synthesis film, that is, (1) blue light reflects blue light and transmits green and red light. A dichroic film (for convenience, this film is reflected by a “dichroic film 45”) and is emitted. (2) Green light reflects a green ray and transmits a red ray (for convenience, this membrane is referred to as “ The reflected light is transmitted through the dichroic film 45 and emitted, and (3) the red light is transmitted through the dichroic films 45 and 44 and is emitted. The configuration can be cited.

Hereinafter, an illumination device and a projection display device according to the present invention will be described in detail with reference to the drawings.
The illumination device of the present invention includes a light source including a semiconductor light emitting device that selectively emits light from a plurality of light emitting elements having different emission wavelengths. As the light source, as shown in FIG. 2A, LEDs (R LED, G LED, and B LED) 23 that individually emit R (red), G (green), and B (blue), respectively. An LED array containing at least one to 25 for each color can be used.
For example, as shown in FIG. 2B, the high-power LEDs for each color light of R, G, and B are arranged in a straight line, and each color of R, G, and B is suitable for a small projection display device. For example, a light source that emits light in order of time can be obtained.

  The illuminating device of the present invention comprises a uniform illuminating means that is made of a transparent member with respect to the light source and uniformly illuminates the light valve with light from the light source. As such uniform illumination means, as shown in FIG. 3 (a) or (b), the first surface 31 having an area equal to or larger than (or equal to or larger than) the area of the light source; 3A having a larger area than the surface 31 and having a second surface 32 opposite to the first surface 31, and is incident from the first surface 31 and exits from the second surface 32. Or rod lenses 3 and 3 'shown in FIG. Preferably, each light emitting color has a rod lens array as shown in FIG. 4 formed integrally with the LED array arranged so that light rays from each light emitting surface of the LED array can be efficiently coupled. A rod lens array light source as shown in 2 of FIG. As shown in FIG. 2 (A), the illumination device of the present invention couples the light emitted from each rod lens 3 to the second surface 32 side of each rod lens 3 of the rod lens array. An optical path synthesis prism array 4 in which optical path synthesis prisms 41 to 47 for synthesizing the optical paths of the respective color lights are arranged.

  Here, the light source composed of the above-described light emitting device (semiconductor light emitting device) is disposed on the first surface 31 side of each rod lens of the rod lens array 3, and a plurality of optical paths of the optical path combining prism array 4. A light source that emits light on the long wavelength side is arranged on the side where the number of times of passing through the synthetic film is larger. That is, in FIG. 2A, 25 is a short-wavelength B LED, 24 is a long-wavelength G LED, and 23 is a long-wavelength R LED.

  The image display device of the present invention is time-division driven in synchronization with the illumination device and the emission timing of each light emitted in order of time from the optical path synthesis means, and is modulated in accordance with the projected image information. The light modulator 5 is composed of a light valve 5, and more preferably includes a projection unit 6 for enlarging and projecting light modulated by the light modulation unit, and a screen 7 for displaying an enlarged image. .

  Here, when a fly eye integrator is used as the uniform illumination means used in the illumination apparatus of the present invention, a space is required between the two fly eye lenses constituting the fly eye integrator and between the fly eye integrator and the light valve. This is an obstacle to miniaturization and thinning of the device (note that the fly eye integrator is installed in front of the light valve and the prism array exists. In this case, the prism array is located between the light source and the fly eye integrator. Between the fly eye integrator and the light valve). In contrast, in the illumination device of the present invention, as shown in FIG. 2A, when a rod lens array in which a plurality of rod lenses are arranged in a straight line is adopted, the fly eye integrator and the illumination uniformity The principle is different, and the incident light repeatedly undergoes internal reflection within the rod lens, and light with uniform illuminance is emitted on the exit end face 32 side. Therefore, there is no need to create a space between the fly integrator and other elements and the fly integrator as in the case of using a fly eye integrator, and it can be placed in close contact with the light source and the light bulb, etc. It is more advantageous than using a fly-eye integrator in terms of promoting thinning.

Further, by adopting a configuration in which the prism array has at least one total reflection prism, in the present invention, a reflection film for light having a long wavelength with the largest light loss due to the angular characteristics of the optical path synthesis film can be made unnecessary. As a result, light loss due to the angle characteristics of the optical path synthesis film can be reduced, and an illumination device with high light utilization efficiency can be obtained .

  Further, as shown in FIG. 4, in the light source used in the illumination device of the present invention, as shown in FIG. 3A, the light emitting surface and the rod lens are transparent members with respect to the light from the light source. It is desirable that it is filled with or is adhered by a transparent member. This eliminates the interface between the LED chip and air, suppresses total reflection at the interface, and improves the light extraction efficiency from the LED chip.

As shown in FIG. 3, the rod lens 30 has a film, a diffraction grating, and a light reflecting layer for reflecting light from the light source on a rod lens side surface 34 that connects the first surface 31 and the second surface 32. Due to the formation of a sub-wavelength fine structure or the like, the light beam incident on the side surface 34 of the rod lens at a small incident angle is kept in the rod lens so as not to leak from the side surface of the rod lens and is directed toward the second surface 32. Light utilization efficiency can be improved.
Further, a polarizer can be arranged on the second surface 32 side of the rod lens array to align the polarization, and the present invention can be applied to a projector illumination optical system using a liquid crystal light valve. The position where the polarizer is disposed may be either on the second surface, on the incident surface of the prism array, or between the rod lens and the prism array.

  Further, by making the polarizer disposed on the second surface 32 side of the rod lens array a reflective polarizer, the light beam that has not passed through the polarizer is returned to the rod lens and propagated in the LED direction. If the light emitting surface of the LED is the front surface (front surface), the light is reflected by the reflecting structure formed on the back surface of the LED on the back side of the light emitting surface of the LED, and is again directed to the exit surface direction of the rod lens (as viewed from the LED). Can be reused by being propagated in the direction of the surface), and the light utilization efficiency can be improved. Furthermore, it is desirable that the polarizer is directly formed on the second surface of the rod lens array.

Further, since the rod lenses 30 of the rod lens array are integrally molded, the number of assembling steps can be reduced, the productivity can be increased, and the cost can be reduced.
In addition, it is desirable that the light source is disposed on one substrate, and it is desirable that wiring is performed as the same electrode of the light source that emits the same color in order to simplify the wiring.
In addition, by making the first and second surfaces of the rod lens array curved, light rays with a large divergence angle can also satisfy the total reflection condition, and a reflecting film, diffraction grating, or wavelength on the side surface of the rod lens. Light utilization efficiency can be improved without forming the following fine structure. In addition, the angle of emission from the rod lens can be made narrower.

  Hereinafter, the image display device using the illumination device of the present invention will be further described with reference to examples.

[Example 1]
First, a first embodiment will be described with reference to FIGS. In this embodiment, an example of a projection-type color display device of a color sequential drive system that uses a liquid crystal panel to sequentially turn on R, G, B and color-synthesize a color image in a person's head by an afterimage. Show.
FIG. 2A is a schematic diagram showing the overall configuration of a projection display device, in which reference numeral 2 denotes an LED array (light source), 3 denotes a rod lens array (homogenization / light angle conversion means), and 4 denotes an optical path. A synthesis prism array (light path synthesis means), 5 is a transmission type liquid crystal light valve (light modulation means), 6 is a projection lens (projection means), and 7 is a screen. The alternate long and short dash line represents the optical axis of the optical system. The illuminating device of the present invention comprises an LED array 2 as a light source, a rod lens array 3 as a homogenization / ray angle conversion means, and an optical path synthesis prism array 4 as an optical path synthesis means.

  Each LED coupled to each rod lens 30 of the rod lens array 3 has one color, but the number of chips (light emitting units: LEDs of the same color) is not limited to one. However, in order to efficiently convert the light beam angle of the light emitted from the LED within the light beam capture angle of the light valve, it is preferable that the ratio of the area of the light emitting portion to the area of the light valve is small. Specifically, for a 0.2 inch diagonal (vertical x horizontal: 3 mm x 4 mm) light bulb, square LED chips with a side of 1 mm are arranged in a one-dimensional (straight) one-dimensional (straight) manner at 4.4 mm intervals. To form RGB light sources 23-25.

  Three LEDs in the LED array 2 are installed on one substrate 21 and connected to a light source driving circuit (light source driving means) (not shown), and the light emission timings of the LEDs 23 to 25 are controlled by the light source driving circuit. It is configured to be capable of emitting each color light from the LEDs 23 to 25, for example, in the order of R, G, B, R, G, B,. At this time, terminals that can be shared by the LEDs can be connected on the substrate 21 to simplify the wiring.

Each of the red LED (R LED) 23, the green LED (G LED) 24, and the blue LED (B LED) 25 has a one-to-one correspondence with the rod lens for uniforming the illuminance and converting the light angle of each color light emitted. It is combined with.
The shape of a single rod lens is shown in FIG. The shape of the rod lens is such that the first surface 31 on the LED side has almost the same area as the light emitting surface of the LED, and the second surface 32 that faces the surface and emits light has a larger area than the first surface. It has become. The light beam emitted from the LED is coupled to the rod lens, and the light traveling in the direction of the surface (side surface) 34 connecting the first surface and the second surface of the rod lens is reflected by the side surface 34 a plurality of times, for example. Is made uniform and the ray angle is converted. Specifically, the first surface is a 1 mm square with the same shape as the LED, the second surface is a 4 mm × 4.4 mm rectangle, and the second surface has a radius of curvature R = 3.29 mm. Suppose that it has a lens shape. The distance between the first surface and the top of the second surface is set to 6 mm, the illuminance of the emitted light is made uniform, and the angle conversion is performed efficiently.

  At this time, the surface connecting the first surface (incident end surface 31) and the second surface (outgoing end surface 32), that is, the reflecting film, the diffraction grating, or the above-described reflecting light beam of the wavelength of the light source light on the side surface 34 of the rod lens. By forming a fine structure shorter than the wavelength, the light use efficiency of the emitted light from the light source can be improved. Further, as shown in FIG. 6, by making the side surface 34 an appropriate curved surface (continuous curved surface), the side surface 34 satisfies the total reflection condition for the light emitted at a large angle with respect to the optical axis, and the reflective film Alternatively, if there is no reflecting structure, it is possible to reduce the loss of high-order light such as secondary light due to reflection loss, diffraction loss, etc. from the side surface of the rod lens, and to improve the light utilization efficiency. Further, by making the side surface 34 of the rod lens 30 a curved surface, the divergence angle of the emitted light can be set to a desired angle, so that it can be kept narrow.

The incident end surface 31 of the rod lens 30 may not be a flat surface, but may be a curved surface, for example, a hemispherical curved surface as shown in FIG. At this time, the space between the LED and the rod lens is filled with a medium 33 that is optically transparent with respect to the light from the light source or is adhered with such an adhesive, so that total reflection in the LED chip is suppressed. The light extraction efficiency from the chip can be improved.
The transparent medium 33 may be an adhesive itself, or filled with a transparent medium that is hardly deteriorated by light or heat, such as a silicone resin, thereby suppressing a decrease in transmittance due to the fact that the medium is hardly deteriorated even when used for a long time. can do. In addition, the rod lens array may be formed as a single unit for each color, but it is desirable that the rod lens array be integrally formed of resin or glass.

  As shown in FIG. 2, the light beam from the LED emitted from the rod lens array 30 is coupled to the optical path synthesis prism array 4. The optical path synthesizing prism array 4 is composed of three prisms including one rectangular prism 41 and two cube-shaped prisms 42 and 43 in which dichroic films 44 and 45 are vapor-deposited on the joint surface of the two rectangular prisms. Has been. The light beam emitted from the red LED 23 is coupled to the right-angle prism 41 and totally reflected by the inclined surface 46 of the right-angle prism. The right-angle prism 46 functions as a total reflection prism for red LED light. The totally reflected red light beam passes through the dichroic films 44 and 45 of the two cube-shaped dichroic prisms 42 and 43 connected to each other and is emitted from the emission surface 47 of the optical path synthesis prism array 4. The light beam emitted from the green LED 24 is coupled to the cube-shaped dichroic prism 42, reflected by the dichroic film 44 of the dichroic prism 42, passes through the dichroic film 45, and is emitted from the emission surface 47 of the optical path synthesis prism array 4. Emitted. Thus, the dichroic film 44 has a characteristic of transmitting red light and reflecting green light. The light beam emitted from the blue LED 25 is coupled to the cube-shaped dichroic prism 43, reflected by the dichroic film 45 of the dichroic prism 43, and emitted from the emission surface 47 of the optical path synthesis prism array 4. Therefore, the dichroic film 45 has a characteristic of transmitting red light and green light and reflecting blue light.

  In this way, as shown in FIG. 2 (A), the LED that emits red color light from the light exit surface 47 of the optical path synthesis prism is the largest for the light on the long wavelength side where the change in film characteristics with respect to the incident angle is large. It arrange | positioned in a distant position and arrange | positioned so that the frequency | count (in this case 2 times) which permeate | transmits the optical path synthetic | combination film | membrane of an optical path synthetic | combination prism array may become the largest. In addition, for green color light having the second longest wavelength, an LED that emits green color light is arranged so that the number of times of transmission is second through the optical path synthesis film. The blue color light having the shortest wavelength is configured to reflect only without passing through the optical path synthesis film. Thus, by arranging the LEDs so as to adjust the number of times each color LED light source passes through the optical path synthesis film in the order of the wavelength length, the above-described problem due to the angle dependency of the optical thin film can be solved. .

At this time, as shown in FIG. 5, when the prisms of the optical path combining prism are bonded with an adhesive having a low refractive index, the light beam angle-limited by the rod lens escapes from the prism as indicated by the dotted line ( It efficiently reaches the exit surface of the optical path synthesis prism without being dissipated. However, if it is adhered with an adhesive having a refractive index equal to or higher than the refractive index of the prism material, the light beam will escape (dissipate) To do). Here, according to “Latest projector technology” (CMC Publishing Co., Ltd., p. 78-79), the light bulb capture angle is about 12 degrees in the case of a liquid crystal light valve. the When 1.52, by using the n = 1.4 or less of the refractive index of the adhesive, can be emitted rays within the maximum take-angle of the light valve from the exit surface 47 without any loss optical path synthesizing prism .

Here, it is desirable for each prism (one right-angle prism and two cube prisms) to be bonded with the above-described adhesive having a low refractive index in terms of characteristics and handling, but the respective prisms are closely bonded without bonding. In addition, a method of mechanically fixing the optical system housing with a leaf spring or the like may be employed .

  Light rays emitted from the emission surface 47 of the optical path synthesis prism array 4 enter the transmissive liquid crystal light valve 5. The liquid crystal light valve 5 uses a TN (Twisted Nematic) mode active matrix type transmissive liquid crystal cell using a thin film transistor (TFT) as a pixel switching element. A polarizing plate and an output-side polarizing plate are provided so that their transmission axes are orthogonal to each other. For example, in the off state, s-polarized light incident on the liquid crystal light valve 5 is converted into p-polarized light and emitted, while in the on state, light is blocked. The above LED array 2, rod lens array 3, optical path combining prism array 4 and liquid crystal light valve 5 may be arranged apart from each other, and are arranged in close contact with each other in order to reduce the size and thickness of the apparatus. It is desirable.

  The liquid crystal light valve 5 is connected to a liquid crystal light valve driving circuit (light modulation driving means) (not shown), and the liquid crystal light valve 5 can be driven in time order corresponding to each color light incident by the liquid crystal light valve driving circuit. It has become. In addition, the projection type display device of this embodiment is provided with a synchronization signal generation circuit (synchronization signal generation means), and the synchronization signal generation circuit generates a synchronization signal to generate a light source drive circuit and a liquid crystal light valve drive circuit. , It is possible to synchronize the timing of emitting the color light from each of the LEDs 23 to 25 and the timing of driving the liquid crystal light valve 5 corresponding to the color light.

That is, in the projection type display apparatus according to the present embodiment, one frame is divided in time, and each color light of R, G, B is emitted from the LEDs 23 to 25 in time order, and the color light is emitted from each LED 23 to 25, and the liquid crystal In synchronization with the timing of driving the light valve 5, the liquid crystal light valve 5 is driven in time order corresponding to the color light emitted from each LED 23-25, and the image signal corresponding to the color light emitted from each LED 23-25. Is output, and a color image can be synthesized.
Thereafter, the image formed by the liquid crystal light valve 5 is enlarged and projected onto the screen 7 by the projection lens 6.

[Embodiment 2] Hereinafter, an image display device using the illumination device of the present invention of the present invention will be described with reference to FIGS. 7 to 9 according to a second embodiment.
FIG. 7 is a schematic diagram showing the configuration of the entire projection display apparatus. The difference from the first embodiment that the polarizing plate 71 to 73 is disposed between the rod lens array and the optical path synthesizing prism (e.g. on the second surface of the rod lens array) is different. The detailed structure of the LED array portion is shown in FIG.

  In FIG. 8, a G LED will be described as an example. First, a reflective surface 26 is formed on the back surface (back surface) 22 of the LED chip 24. The reflective surface is made of a metal or dielectric multilayer film, which is formed by vapor deposition of metal or dielectric multilayer film, or the LED substrate 21 is formed of metal, and the peripheral portion 26 of the LED chip 24 is shown in FIG. When the LED light emitting surface as shown in 2 (B) is rectangular (including a square), it has a rectangular shape, and is formed by mirror processing.

  With this configuration, the light emitted from each LED chip 23 to 25 is coupled to each rod lens array 3, and then internally reflected by each rod lens is repeatedly emitted from the emission end face to reflect each LED chip. Due to the type polarizers 71 to 73, one polarization component passes through the reflection type polarizer as it is and goes toward the light valve 5. The polarized light component in the direction orthogonal to it is reflected by the reflective polarizer and returns to the LED chip direction (returned light), reflected by the LED chip back surface and the surrounding reflecting surface 26, and again internally reflected by each rod lens to the exit end surface. To reach. The direction of polarization of these light beams is rotated by reflection in the rod lens a plurality of times, and a part of the return light due to the reflection described above is transmitted by the reflective polarizer and emitted to the light valve 5 (that is, one of the return lights). Department reuse). Such reuse of the return light is repeated many times, and illumination light with a uniform polarization direction can be obtained with high utilization efficiency. Since the light valve and subsequent parts are the same as those described in the first embodiment, a description thereof will be omitted.

The reflective polarizer may be formed directly on the exit end face 32 of the rod lens 3. An example of the structure of the reflective polarizer in that case is shown in FIG. A dielectric film 42 having a high refractive index and a dielectric film 43 having a low refractive index are alternately stacked on the emission end face 32 of the rod lens array 3 molded of glass, and a stripe-like periodic structure is formed by etching. As shown in FIG. 9, in the periodic structure of the stripes, the portions having a height of L shown in the figure are arranged in the horizontal direction on the paper with a period p. For example, TaO 5 (refractive index: n≈2.2) is used as the high refractive index material, and SiO 2 (refractive index: n≈1.44) is used as the low refractive index material, and the stripe structure pitch p, filling density Filling Factor (land By optimizing the width Δ / pitch p) and the layer thickness L, it functions as a reflective polarizer that transmits p-polarized light (polarized component in the stripe direction) and reflects s-polarized light (polarized component orthogonal to the stripe direction). . Here, by selecting a higher refractive index material having a higher refractive index and increasing the number of layers, a structure having a function of a reflective polarizer in a wider wavelength range can be created. Further, instead of the dielectric multilayer film, a large number of ribs (light reflectors) made of a metal having light reflectivity such as aluminum may be formed on the exit end face of the rod lens array at a pitch smaller than the wavelength of incident light. Good. In this case, a reflective polarizer having a rib structure can be formed by depositing and etching a metal thin film on the exit end face of the rod lens array in the same manner as the dielectric film.

Example 3
Hereinafter, an image display device using the illumination device of the present invention will be described with reference to FIG. 10 according to a third embodiment.
This embodiment is also a color sequential drive type projection display device, but is different from the above embodiment in that the light valve uses a mirror type instead of a liquid crystal.
FIG. 10 is a schematic diagram showing the overall configuration of the image display apparatus. The image display device includes an illumination device including an LED array (light source) 2, a rod lens array (homogenization / light angle conversion means) 3, an optical path synthesis prism (optical path synthesis means) 4, a deflection prism 8, The modulation means includes a mirror type light valve 9, a projection lens (projection means) 6, and a screen 7.

  The configuration up to the optical path combining prism array 4 is the same as that of the first or second embodiment, and the description up to here is omitted. The light emitted from the optical path synthesis prism array 4 is formed by adhering two triangular prisms 81 and 82 using an air layer or an adhesive having a refractive index smaller than the refractive index of the prism, or filling with a transparent medium. Is incident on the deflecting prism 8, is totally reflected by the inclined surface 84 of the triangular prism 81, and enters the mirror type light valve 9 at a predetermined angle. The mirror type light valve 9 uses a mirror array formed by a semiconductor process as a pixel switching element. As such a mirror array, a digital mirror device (DMD) manufactured by Texas Instruments can be used. In such a mirror array, for example, in the off state, the mirror tilt is zero degrees and is not coupled to the projection lens 6. However, in the on state, the mirror has a predetermined tilt so that light rays are reflected toward the projection lens 6. Therefore, the mirror reflected light deviates from the total reflection condition of the inclined surface of the triangular prism 81, passes through the deflecting prism 8, and is imaged on the screen 7 by the projection lens 6. When the mirror type light valve 9 is used, since a configuration without using polarized light can be taken, there is no need for polarization conversion, so that illumination light can be effectively guided to the projection lens. Therefore, it is possible to provide a bright projection display device with high light utilization efficiency as in this embodiment.

Example 4
Hereinafter, an image display device using the illumination device of the present invention will be described with reference to FIG. 11 according to a fourth embodiment.
FIG. 11 is a schematic diagram showing the overall configuration of the image display apparatus. The overall configuration of the image display apparatus is the same as that of FIG. 2, but the rod lens array is filled with a medium in the rod lens of the above-described embodiment, whereas in this embodiment, a hollow rod is used. It is a point using a lens. The rod lens portion is configured with the shape of the rod lens as a hollow body. Therefore, it is possible to make the rod lens not only from resin (for example, transparent resin) but also from metal. In that case, the reflecting surface can be easily formed by mirror-processing the side surface in the rod lens. Alternatively, when a portion other than the hollow rod lens portion is made of a resin, it is necessary to have a reflection film or a structure that reflects the light beam on the side surface in the rod lens that reflects the light beam. For example, after forming the rod into a hollow shape as shown in FIG. 3 with a resin, the side surface of the hollow rod is processed to have less irregularities, and then a metal or dielectric film is formed by vapor deposition as described above. And can be formed in a mirror shape.

Example 5
Hereinafter, an image display device using the illumination device of the present invention will be described with reference to FIG. 12 according to a fifth embodiment.
FIG. 12 is a schematic diagram showing the overall configuration of the image display apparatus. The overall configuration of the image display apparatus is the same as that of FIG. 2 except that the configurations of the LED array 2, the rod lens array 3, and the optical path combining prism array 4 are different.
That is, as shown in FIG. 12, in the LED array 2, two light sources, a green LED 24 and a blue LED 25, are linearly arranged, and the red LED 23 has an optical axis of the emitted light of the two-color LED. Is arranged on the extension line of the optical axis of the optical path synthesis prism. Corresponding to the arrangement of the light sources, the rod lens 3 is also an array of a green rod lens 32 and a blue rod lens 33, and the red rod lens 31 is a light beam from the optical path combining prism on the red LED 23 side. It is arranged on the extension line of the shaft. The optical path combining prism array 4 is constituted by a prism array including two cube type dichroic prisms 42 and 43.

The light beam emitted from the red LED 23 passes through the dichroic films 44 and 45 of the two cube-shaped dichroic prisms 42 and 43 connected to each other, and is emitted from the emission surface 47 of the optical path synthesis prism array 4. Light rays emitted from the green LED 24 are coupled to a cube-shaped dichroic prism 42, reflected by the dichroic film 44 of the dichroic prism 42, and emitted from the emission surface 47 of the optical path synthesis prism array 4. Therefore, as described in the first embodiment, the dichroic film 44 has a characteristic of transmitting red light and reflecting green light. The light beam emitted from the blue LED 25 is coupled to the cube-shaped dichroic prism 43, reflected by the dichroic film 45 of the dichroic prism 43, and emitted from the emission surface 47 of the optical path synthesis prism array 4. Accordingly, as described in the first embodiment, the dichroic film 45 has a characteristic of transmitting red light and green light and reflecting blue light.
Light rays emitted from the emission surface 47 of the optical path synthesis prism array 4 enter the transmissive liquid crystal light valve 5. Since the subsequent steps are the same as those in the first embodiment, the description thereof is omitted.

  In this way, a long wavelength light beam (in this case, an LED that emits red color light) having a large amount of change in the film characteristic with respect to the incident angle on the long wavelength side is emitted from the light source of the emitted light used for the light source. It arrange | positioned so that the frequency | count (2 in this case) which permeate | transmits the some optical path synthetic | combination film | membrane of the synthetic | combination prism array 4 may become the largest. In addition, an LED that emits green color light is disposed so that the second number of times of green color light having the longest wavelength is secondly transmitted through the optical path synthesis film. The blue color light having the shortest wavelength does not pass through the optical path synthesis film and is configured to reflect only. Thus, the LED light sources of the respective colors are arranged to solve the above-described problem due to the angle dependency of the optical thin film.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, as the light source, a semiconductor laser, an organic EL element, an inorganic EL element, or the like can be used in addition to the LED.
Further, it is sufficient that the number of LED chips of each color in each LED array is one or more, and it can be configured by an appropriate number of chips for each color from the relationship between the LED output capability and white balance.

It is a figure which shows the characteristic of the film | membrane which was made as an experiment. (A) is a figure which shows the 1st structural example of the image display apparatus using the illuminating device of this invention, (B) is a figure which shows the example of a shape of the light emitting element used for the illuminating device of this invention. It is a figure which shows the example of a shape of the rod lens used for the illuminating device of this invention. It is a figure which shows the example of the rod lens array formed integrally with the LED array. It is a figure for demonstrating the advancing direction of a light beam when each prism of the optical path synthetic | combination prism used for the illuminating device of this invention is adhere | attached with the adhesive agent with a low refractive index. It is a figure which shows the example of a shape of the rod lens used for the illuminating device of this invention, and is a figure which shows the example by which the side surface is formed in the appropriate curved surface (continuous curved surface). It is a whole structure schematic diagram which shows the 2nd example of the projection type display apparatus of this invention. It is a figure which shows the detailed structure of the LED array in which the reflective surface is formed in the back surface of a chip | tip. It is a figure which shows the structural example of the reflection type polarizer directly formed in the output end surface of a rod lens. It is a whole structure schematic diagram which shows the 3rd example of the image display apparatus of this invention. It is a whole structure schematic diagram which shows the 4th example of the image display apparatus of this invention. It is a whole structure schematic diagram which shows the 5th example of the image display apparatus of this invention. This is a conventional projection type image display device.

Explanation of symbols

2 LED array (light source)
3 Rod lens array (uniform illumination means)
4 Optical path synthesis prism array (optical path synthesis means)
5 Transmission type liquid crystal light valve (light modulation means)
6 Projection lens (projection means)
7 Screen 21 Substrate 23 Red light emitting element (longest wavelength light emitting element)
24 Green light-emitting element (intermediate wavelength light-emitting element)
25 Blue light-emitting element (shortest wavelength light-emitting element)
30 Rod lens 31 First surface of rod lens array (coupling surface with LED array)
32 Second surface of rod lens array 34 Side surface of rod lens array 41 Right angle prism in optical path combining prism 42, 43 Cubic prism 44, 45 Dichroic film of right angle prism constituting cube prism 46 Slope of right angle prism 41 Outgoing surface of optical path synthesis prism array 4 52 High refractive index material 53 Low refractive index material 71 Longest wave polarization plate 72 Intermediate wavelength polarization plate 73 Shortest wavelength polarization plate

Claims (11)

  1. A light source composed of a semiconductor light emitting device that emits light by selecting a plurality of light emitting elements having different emission wavelengths according to colors;
    The first surface is made of a member that is transparent to the light emitted from the light source, and has an area equal to or larger than the area of the light source, and has an area larger than the first surface and faces the first surface. A rod lens array in which rod lenses having a second surface are arranged;
    An illumination device configured with an optical path synthesis prism array in which optical path synthesis prisms having a dichroic mirror for coupling light emitted from each rod lens are arranged on the second surface side of each rod lens of the rod lens array. ,
    The light source is arranged on the first surface side of each rod lens of the rod lens array, and is arranged such that the wavelength light of the light source becomes longer as the number of transmissions of the dichroic mirror of the optical path synthesis prism array increases. ,
    The prism array has at least one total reflection prism;
    Between the optical path combining prisms of the optical path combining prism array is adhered with an adhesive having a refractive index of 1.4 or less,
    The illumination device according to claim 1, wherein a side surface connecting the first surface and the second surface of the rod lens has a fine structure shorter than a wavelength of the light source .
  2. Side of the first surface and the rod lens connecting the second surface of the rod lens, the illumination device according to claim 1, wherein the substantially reflecting the light emitted from the light source.
  3. The lighting device according to claim 1 or claim 2, characterized in that disposed a polarizer on the second surface side of the rod lens array.
  4. The lighting device according to claim 3 , wherein the polarizer is a reflective polarizer.
  5. The lighting device according to claim 4 , wherein the polarizer is formed on the second surface of the rod lens array.
  6. The illumination device according to any one of claims 1 to 5 , wherein each rod lens of the rod lens array is formed integrally.
  7. Lighting device according to any one of claims 1 to 6, characterized in that said light source is disposed on one substrate.
  8. The lighting device according to any one of claims 1 to 7 , wherein the same electrode of a light source that emits the same color is connected.
  9. The illumination according to any one of claims 1 to 8 , wherein a side surface that is a surface connecting the first surface and the second surface of each rod lens of the rod lens array is a curved surface. apparatus.
  10. An image display device comprising: the illumination device according to any one of claims 1 to 9 ; and a light modulation unit that modulates light emitted from the illumination device according to image information.
  11. An illumination device according to any one of claims 1 to 9, a light modulation means for modulating according to image information light emitted from the lighting device, and a lens for enlarging and projecting the modulated light An image display device comprising:
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