JP2007288169A - Optical element, illumination device, and image display device - Google Patents

Abstract

An optical element that is excellent in light use efficiency and can be reduced in size, thickness, and weight with a simple configuration, and an illumination device and an image display device using the optical element are realized.
A light source comprising a light emitting device capable of emitting a plurality of color lights and capable of selectively emitting a desired element as a set, and a member transparent to the light from the light source. A rod lens array in which rod lenses 31 having a first surface having an area equal to or larger than an area and a second surface facing the first surface and having the two surfaces as a bottom surface are two-dimensionally arranged 3 is configured such that a light source 22 composed of a light emitting device having a set of a plurality of colors is arranged on the first surface side of each rod lens 31 of the rod lens array 3. As a result, the emitted light from the light source 22 is made uniform by the respective rod lenses 31, whereby the illuminance can be made uniform for each color light by the second surface 33 of the rod lens array 3.
[Selection] Figure 1

Description

  The present invention relates to a configuration of an image display device, and in particular, an optical element used in the image display device and its illumination system, an illumination device using the optical element, and a small and light weight equipped with the optical element or the illumination device. The present invention relates to a thin image display device.

2. Description of the Related Art Conventionally, a projection type image display apparatus that synthesizes image light using a light modulation device such as a liquid crystal light valve and enlarges and projects the synthesized image light on a screen through a projection optical system including a projection lens or the like is known.
FIG. 11 is a schematic configuration diagram showing an example of a conventional projection type image display apparatus. In FIG. 11, reference numeral 110 is a light source, 113 and 114 are dichroic mirrors, 115, 116 and 117 are reflection mirrors, 122, 123 and 124 are liquid crystal light valves (light modulation means), 125 is a cross dichroic prism, 126 Indicates a projection lens. The light source 110 includes a lamp 111 such as a metal halide and a reflector 112 that reflects the light of the lamp. The dichroic mirror 113 the blue light, green light reflecting transmits a red light L _R of the light beam from the light source 110 and reflects the blue light L _B and the green light L _G. The transmitted red light _LR is reflected by the reflecting mirror 115 and enters the red light liquid crystal light valve 122. Meanwhile, among the color light reflected by the dichroic mirror 113, the green light L _G reflected by the dichroic mirror 114 for reflecting green light, and enters the liquid crystal light valve 123 for green light. On the other hand, the blue light _{L B} passes through even the dichroic mirror 114, passes through the reflecting mirror 116 and 117 enters the liquid crystal light valve 124 for blue light.

  The three color lights modulated by the liquid crystal light valves 122, 123, and 124 enter the cross dichroic prism 125. The cross dichroic prism 125 has four right angle prisms bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected on the projection screen 127 by the projection lens 126 which is a projection optical system, and an enlarged image is displayed.

  As described above, in the conventional projection type image display device, the light emitted from the light source is separated into three color lights using the dichroic mirrors 113 and 114, and each color light is divided into three liquid crystal light valves 122, 123, After being modulated using each of 124, they are synthesized again by the dichroic prism 125 and projected onto the screen 127 by the projection lens 126. For this reason, a large number of optical components are required, and it has been fundamentally difficult to reduce the size, weight, and thickness of the apparatus.

In order to solve this problem, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2003-295315) emits light of each color of red, green, and blue (hereinafter abbreviated as red, green as G, and blue as B). An LED array in which a plurality of possible light emitting diodes (hereinafter abbreviated as LEDs) are arranged in a planar shape or a curved surface, and the illuminance of each color light emitted from each LED of the LED array is made uniform A rod lens array in which a plurality of rod lenses are arranged in a planar or curved surface, a polarization beam splitter array (hereinafter abbreviated as a PBS array) that performs polarization conversion of light emitted from the rod lens array, and a PBS A liquid crystal light valve that synthesizes an image by modulating each color light emitted from the array, and a projection that magnifies and projects the image synthesized by the liquid crystal light valve onto the screen. Projection type image display device is composed of a lens has been proposed.
Patent Document 2 (Japanese Patent Laid-Open No. 2003-329978) discloses an LED array including a reflector on the rear side with respect to the light emitting direction, a retardation plate, a tapered rod lens array, a rod lens array, A thin illumination device that includes a reflective polarizing plate and performs polarization conversion has been proposed.

JP 2003-295315 A JP 2003-329978 A “Latest Projector Technology” (CMC Publishing), p. 77

In the prior art described in Patent Document 1 described above, since the illuminance is uniformed by the rod lens for each color light, one or a plurality of LED chips that have passed through the rod lens on the exit end face of the rod lens. Although the illuminance is uniformized for the color light emitted from the light source, there is a problem in that each color light is not necessarily uniform on the light valve after emitting the rod lens.
In the prior art described in Patent Document 2, as the reflective polarizing plate, a large number of ribs made of a metal having light reflectivity such as aluminum are formed on the glass substrate 25 at a pitch smaller than the wavelength of incident light. A so-called reflective polarizing plate element such as a grid polarizer or a film multilayer laminated polarizing plate is required, which is an adverse effect of thinning.

  The present invention has been made to solve the above-described problems of the prior art, and is an optical element that is excellent in light utilization efficiency and can be reduced in size, thickness, and weight with a simple configuration, and the optical element. An object of the present invention is to provide a small, thin, light image display device or lighting device using the above, and a small, thin, light image display device including the lighting device.

In order to achieve the above object, the present invention employs the following technical means.
The first means of the present invention includes: “a light source composed of a semiconductor light-emitting device capable of emitting a plurality of color lights and capable of selectively emitting a desired element and combining a plurality of colors” and “light from the light source” A first surface having an area equal to or larger than the area of the light source, and a second surface facing the first surface, the two surfaces being A rod lens array in which rod lenses serving as a bottom surface are two-dimensionally arranged ”, and“ from a semiconductor light emitting device having the plurality of colors as a set on the first surface side of each rod lens of the rod lens array ” The light source to be comprised is arrange | positioned. "

  According to a second means of the present invention, “a light source composed of a semiconductor light-emitting device capable of emitting a plurality of color lights and selectively emitting a desired element and combining a plurality of colors” and “light from the light source” A first surface having an area equal to or larger than a light emitting portion area of the light source, and a first surface having an area larger than the first surface and facing the first surface. A rod lens array in which rod lenses having two surfaces as a bottom surface are arranged in a two-dimensional manner, on the first surface side of each rod lens of the rod lens array. , A light source composed of a semiconductor light emitting device having the plurality of colors as a set is disposed.

  According to a third means of the present invention, “a light source composed of a semiconductor light-emitting device capable of emitting a plurality of color lights and capable of selectively emitting a desired element and combining a plurality of colors” and “a light emitting unit of the light source” A first opening surface having an area equal to or larger than the area, and a second opening surface having an area larger than the first opening surface and facing the first surface, the two In the optical element composed of a rod lens array in which a film or structure reflecting light source light is formed on the side surface of the hollow rod lens having the opening surface as a bottom surface, and the hollow rod lenses are two-dimensionally arranged. A light source composed of a semiconductor light emitting device having the plurality of colors as a set is disposed on the first opening surface side of each hollow rod lens of the rod lens array.

According to a fourth means of the present invention, there is provided the optical element of any one of the first to third means, wherein “the light source composed of the semiconductor light emitting device having the plurality of colors as one set is red (R), green (G) is a light source composed of a semiconductor light emitting device having at least three colors of blue (B) as a set.
According to a fifth means of the present invention, in the optical element of the first or second means, “the space between the light source and the rod lens is filled or adhered by a member transparent to the light from the light source. It is characterized by.
Furthermore, a sixth means of the present invention is the optical element of any one of the first to third means, wherein “on the side surface of the rod lens which is a surface connecting the first surface and the second surface of the rod lens. , A film or a structure reflecting light from the light source is formed.

The seventh means of the present invention is characterized in that in the optical element of any one of the first to sixth means, a polarizer is provided on the second surface side of the rod lens array.
The eighth means of the present invention is the optical element of the seventh means, characterized in that “the polarizer is a reflective polarizer”.
Further, the ninth means of the present invention is the optical element of the eighth means, characterized in that “the polarizer is formed on the second surface of the rod lens array”.

The tenth means of the present invention is characterized in that in the optical element of any one of the first to ninth means, “the rod lenses of the rod lens array are integrally molded”.
The eleventh means of the present invention is the optical element of any one of the first to tenth means, wherein “the light source disposed on the first surface side of each rod lens of the rod lens array is a desired one. It is a light quantity ratio for obtaining a white balance ".
The twelfth means of the present invention is characterized in that in the optical element of any one of the first to eleventh means, the light source is disposed on a single substrate.

The thirteenth means of the present invention is characterized in that in the optical element of any one of the first to twelfth means, “the same electrode of the light source emitting the same color is connected”.
According to a fourteenth means of the present invention, in the optical element of any one of the first to thirteenth means, “a first surface and a second surface of each rod lens of the rod lens array, or a first surface, The surface connecting the opening and the second opening is a curved surface.
Further, the fifteenth means of the present invention is an illumination device, characterized in that the optical element of any one of the first to fourteenth means is used.

A sixteenth means of the present invention is an image display device, comprising the illuminating device of the fifteenth means, and a light modulating means for modulating light emitted from the illuminating device according to image information. And
According to a seventeenth aspect of the present invention, there is provided a projection-type image display device, the illumination device of the fifteenth unit, and a light modulation unit that modulates light emitted from the illumination device according to image information, And a lens for enlarging and projecting the modulated light.
Further, an eighteenth means of the present invention is an image display device, wherein the optical element of any one of the first to fourteenth means and the modulated light emitting means for modulating and emitting the light source of the optical element according to image information. The light output from each rod lens of the rod lens array of the optical element is an output of one pixel.
According to a nineteenth means of the present invention, the image display device according to the eighteenth means and a lens for enlarging and projecting the image of the image display device are provided.

  In the optical element of the first means, a light source composed of a semiconductor light emitting device having a set of a plurality of colors is arranged on the first surface side of each rod lens of a rod lens array in which rod lenses are two-dimensionally arranged. Therefore, the illuminance can be made uniform for each color light on the second surface (emission end surface) of the rod lens array by making the emitted light from each light source uniform with one rod lens.

  In the optical element of the second means, a light source composed of a semiconductor light emitting device having a set of a plurality of colors is arranged on the first surface side of each rod lens of a rod lens array in which tapered rod lenses are two-dimensionally arranged. Therefore, the illuminance of each color light is made uniform on the second surface (outgoing end face) of the rod lens array by making the emitted light from each light source uniform with a single tapered rod lens. And the radiation angle of the light beam can be reduced.

  In the optical element of the third means, a light source composed of a semiconductor light emitting device having a set of a plurality of colors is arranged on the first opening surface side of each hollow rod lens of the rod lens array in which the hollow rod lenses are two-dimensionally arranged. Therefore, the illuminance can be made uniform for each color light at the exit end surface of the rod lens array by making the emitted light from each light source uniform with each hollow rod lens. In addition, by using a hollow rod lens, it is possible to easily create a mold. Further, by making it possible to use a metal other than a transparent member such as glass or resin, the selectivity of the material can be expanded.

In the optical element of the fourth means, in addition to the configuration and effect of any one of the first to third means, red (R), green (G), blue ( By using a light source composed of a semiconductor light-emitting device having at least three colors of B) as a set, an optical element capable of full color can be provided.
In the optical element of the fifth means, in addition to the configuration and effect of the first or second means, the space between the light source and the rod lens is filled with a member transparent to the light source light, so that the semiconductor light emitting device The efficiency of extracting light from the LED chip can be improved by eliminating the interface between the light-emitting diode (LED) chip and the air and suppressing total reflection at the interface.
Further, in the optical element of the sixth means, in addition to the configuration and effect of any one of the first to third means, a film or structure that reflects the light source light is formed on the side surface of the rod lens, thereby reducing the incidence of light. Light incident on the side of the rod lens at a corner can be kept in the rod lens, and light utilization efficiency can be improved.

In the optical element of the seventh means, in addition to the configuration and effect of any one of the first to sixth means, a polarizer is installed on the second surface side of the rod lens array, and the polarization is aligned. The present invention can be applied to an illumination optical system of an image display device using a light valve configured as follows.
In addition, in the optical element of the eighth means, in addition to the configuration and effects of the seventh means, by making the polarizer a reflective polarizer, the light beam that has not passed through the polarizer is returned to the rod lens again, It can be reused and the light utilization efficiency can be improved.
Further, in the optical element of the ninth means, in addition to the configuration and effects of the eighth means, the polarizer is formed on the second surface (outgoing end surface) of the rod lens array, so that the thickness is further reduced. be able to.

In the optical element of the tenth means, in addition to the configuration and effect of any one of the first to ninth means, the rod lenses of the rod lens array are integrally molded, so that productivity is improved and reduced. Cost can be increased.
In the optical element of the eleventh means, in addition to the configuration and effect of any one of the first to tenth means, the light source arranged on the first surface side of each rod lens of the rod lens array is desired A good white balance can be obtained when the light quantity ratio is such that the white balance is obtained.
Further, in the optical element of the twelfth means, in addition to the configuration and effect of any one of the first to eleventh means, the light source is arranged on the single substrate, so that the productivity is increased and the cost is reduced. be able to.

In the optical element of the thirteenth means, in addition to the configuration and effect of any one of the first to twelfth means, the same electrode of the light source that emits the same color is connected, thereby simplifying the wiring of the light source Can be
In the optical element of the fourteenth means, in addition to the configuration and effect of any one of the first to thirteenth means, the first surface and the second surface of each rod lens of the rod lens array, or the first surface The surface connecting the first opening and the second opening is a curved surface. By making this curved surface an appropriate curved surface, a light beam with a large divergence angle satisfies the total reflection condition, and the reflective film is formed on the side surface of the rod lens. Alternatively, light utilization efficiency can be improved without forming a structure. In addition, the angle of emission from the rod lens can be made narrower.
Further, in the illumination device of the fifteenth means, by using the optical element of any one of the first to fourteenth means, the light use efficiency is excellent, and the size, thickness and weight can be reduced with a simple configuration. It is possible to obtain a lighting device with uniform illuminance.

The image display device of the sixteenth means is provided with the illumination device of the fifteenth means and the light modulation means for modulating the light emitted from the illumination device according to the image information, so that it is small, thin and lightweight. An image display device can be realized.
In the image display device of the seventeenth means, the illuminating device of the fifteenth means, a light modulating means for modulating the light emitted from the illuminating device in accordance with image information, and the modulated light is enlarged and projected. By providing the lens, it is possible to realize a small, thin, and light projection type image display device.
The image display device of the eighteenth means further comprises an optical element of any one of the first to fourteenth means and a modulation light emitting means for modulating and emitting light from the light source of the optical element according to image information. By making the light output from each rod lens of the rod lens array of 1 pixel into an output of one pixel, it is excellent in light utilization efficiency, and can be reduced in size, thickness and weight with a simple configuration, and an image capable of image formation A display device can be realized.
The nineteenth image display device includes the eighteenth image display device and a lens that magnifies and projects an image formed on the image display device by the modulated light. A small, thin, and light projection type image display device can be realized.

Hereinafter, the configuration, operation, and effects of the present invention will be described in detail.
The optical element according to the present invention includes at least one light-emitting unit in which one light source emits red, green, and blue (hereinafter abbreviated as R, G, and B). The planar light source can be emitted sequentially, and the light source is composed of a planar light source or a curved surface, and uniform illumination means for uniformizing the illuminance of colored light emitted from the planar light source. . And the illuminating device which concerns on this invention is the structure provided with the said optical element, Furthermore, the image display apparatus which concerns on this invention is time-sequentially through a uniform illumination means from the said illuminating device and the said light source of this illuminating device. And a light modulation means including a light valve that is driven in a time-sharing manner in synchronization with the emission timing of each color light emitted to the light source. Further, when the image display device is a projection type, the illumination device and a light that is time-division driven in synchronization with the emission timing of each color light emitted sequentially from the light source of the illumination device through the uniform illumination means The light modulation means is composed of a bulb and the projection means for projecting the light modulated by the light modulation means.

  As a specific form of the planar light source, a semiconductor light emitting device (LED group) including at least one light emitting element (for example, a light emitting diode (LED)) capable of emitting a plurality of color lights of R, G, and B, respectively. An LED array in which a single light source unit is used and the LED group is arranged in a planar shape or a curved shape can be used. Currently, high-power LEDs are provided for each color light of R, G, B, and this type of LED is arranged in a planar or curved surface in an array to reduce the thickness of the image display device (especially a projection type image). A planar light source suitable for a display device can be obtained.

  As a specific form of the uniform illumination means, it is desirable to use a rod lens array in which a plurality of rod lenses are arranged in a planar shape or a curved shape. Fly eye integrators are well known as uniform illumination means used in projection-type image display devices, but in the case of fly eye integrators, a space is required between two fly eye lenses or between a fly eye integrator and a light valve. This is an obstacle to downsizing and thinning of the apparatus. In contrast, in the case of a rod lens array in which multiple rod lenses are arranged in a flat or curved shape, the principle of uniform illuminance differs from that of a fly eye integrator, and incident light is emitted by repeating internal reflection within the rod lens. Light with already uniform illuminance is obtained at the end face. Therefore, there is no need for a space like a fly-eye integrator, and it can be brought into close contact with a planar light source, a subsequent light valve, and the like, which is advantageous for downsizing and thinning.

  Furthermore, it is desirable to provide polarization conversion means for aligning the polarization state of light incident from the planar light source in one direction. As a specific form, a reflection plate provided on the rear side with respect to the light emission direction of the light source body is provided, and polarized light having a predetermined vibration direction is transmitted to the emission end face of the uniform illumination unit, and the vibration direction A configuration in which a reflective polarizer function for reflecting polarized light in different vibration directions is superimposed may be used. By providing the polarization conversion means in this way, the light emitted from the planar light source can be aligned with the polarized light in one polarization direction that contributes to display by the light valve, so that the light use efficiency can be improved.

[Example 1]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In this embodiment, an example of a color sequential drive type projection type image display apparatus is shown. FIG. 1 is a schematic configuration diagram showing the overall configuration of a projection-type image display device, in which reference numeral 1 denotes an optical element, 2 denotes an LED array (planar light source), 3 denotes a rod lens array (uniform illumination means), 4 is a polarizer, 5 is a liquid crystal light valve (light modulation means), 6 is a projection lens (projection means), and 7 is a screen.

Details of the light source portion (illumination device) of FIG. 1 are shown in FIG. In addition, illustration of the board | substrate 21 is abbreviate | omitted in FIG.
A light emitting element (here, LED) of a semiconductor light emitting device coupled to one rod lens 31 is an LED (red) 23, an LED (green) 24, an LED that can emit light of each color of R, G, B. Specifically, each of the LED groups 22 including one red, two green, and one blue LED chip is used as one light source unit. The LED array (light source) 2 in which the LED group 22 is arranged on a flat or curved single substrate 21 and the illuminance of each color light emitted from each LED 23, 24, 25 of the LED group 22 are made uniform. A plurality of rod lenses 31 are arranged in a plane and the rod lens array 3 formed integrally with resin or glass constitutes the optical element 1, and the polarizer 4 is disposed on the exit end face side of the optical element 1. It arranges and constitutes an illuminating device. The projection-type image display device includes the illumination device, a liquid crystal light valve 5 that synthesizes an image by modulating each color light emitted from the rod lens array 3 of the illumination device, and an image synthesized by the liquid crystal light valve 5. And a projection lens 6 for enlarging and projecting the image on the screen 7.

Here, the reason why the LED chips of the LED group 22 are one red, two green, and one blue is referred to Non-Patent Document 1 (p77 of "Latest Projector Technology" (CMC Publishing)). When three primary color LED light sources of chromaticity coordinates (0.700, 0.299), (0.206, 0.709), and (0.152, 0.026) are used, a white color having a color temperature of 9000K is obtained. For that purpose, the luminous flux ratio is
Red: Green: Blue = 21: 76: 4
Therefore, two green colors were used. However, since the number of LEDs is not a problem, and the light flux ratio is a problem, the number of LEDs that can obtain a necessary light flux ratio may be set. In addition, when a full color is not required, a two-color light source can be used. On the other hand, when higher-definition color expression is required, it is possible to use light sources of four or more colors.

  The LED array 2 is connected to a light source driving circuit (light source driving means) (not shown), and the timing at which the LEDs 23, 24, 25 of the LED group 22 emit light is controlled by the light source driving circuit, and the LEDs 23, 24, 25 are controlled. To, for example, R, G, B, R, G, B,... At this time, wiring can be simplified by connecting the same terminals of the LEDs of the same color on the substrate 21.

The rod lens array 3 is bonded to the LED substrate 21 with a transparent resin adhesive or the like. FIG. 3 shows details of the connecting portion between the LED array 2 and the rod lens array 3. 1 and 3, the left side surface (light source side surface) is the incident end surface 32, and the right side surface (light valve side) is the emission end surface 33. Although the incident end face 32 of the rod lens 31 shown in FIG. 3A is a flat surface, it is not necessary to be a flat surface, and an arcuate shape as shown in FIG. At this time, by enclosing the transparent resin 34 between the rod lens 31 and the LED group 22, total reflection in the LED group 22 is suppressed, and light extraction efficiency from each LED 23, 24, 25 of the LED group 22 is suppressed. Can be improved. The transparent resin 34 used for the sealing may be an adhesive itself, but filling a transparent medium that is hardly deteriorated by light or heat, such as silicon resin, reduces the transmittance due to deterioration of the sealing resin even when used for a long time. Can be suppressed.
Further, the exit surface side of each rod lens 31 of the rod lens array 3 does not need to be a flat surface, and may be a curved surface (lens surface) as shown in FIG. FIG. 14 is a graph in which the horizontal axis represents the length of the rod lens, and the vertical axis represents the proportion of light rays that are coupled within a divergence angle of 15 degrees. The case where the exit surface side is a flat surface (R = ∞), the case where the radius of curvature R of the lens surface is R = 3 mm, and the case where R = 5 mm are shown. By making the exit surface side of the rod lens 31 a lens surface, the length of the rod lens 31 can be shortened.

  Light emitted from the LEDs 23, 24, and 25 of the LED group 22 reaches the incident end face 32 of the rod lens array 3 through a filler or a transparent resin adhesive, and is coupled to the rod lens 31. The coupled light beam repeatedly undergoes internal reflection at each rod lens 31, and the illuminance is uniformed when it is emitted from the emission end face 33. Light rays emitted from the rod lens array 3 are aligned in one direction by the polarizer 4 and enter the liquid crystal light valve 5. At this time, a reflective film or structure that reflects the light beam having the wavelength of the light source light is formed on the surface connecting the first surface (incident end surface 32) and the second surface (exit end surface 33), that is, the side surface of the rod lens 31. Thereby, the light utilization efficiency of the emitted light from a light source can be improved. Further, as shown in FIG. 5, by making the side surface of the rod lens 31 an appropriate curved surface, the side surface satisfies the total reflection condition even for a light beam emitted at a large angle with respect to the optical axis, and the reflection film or the reflection structure Even if there is no loss, loss through the rod lens 31 can be reduced, and the light utilization efficiency can be improved. Further, by making the side surface of the rod lens 31 a curved surface, the divergence angle of the emitted light can be suppressed to be narrow.

  The liquid crystal light valve 5 uses a TN mode active matrix transmission type liquid crystal cell using a thin film transistor (hereinafter abbreviated as “TFT”) as a pixel switching element. An incident side polarizing plate and an outgoing 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. On the other hand, in the on state, light is blocked. The LED array 2, the rod lens array 3, the polarizer 4, and the liquid crystal light valve 5 may be arranged apart from each other, but in order to reduce the size and thickness of the apparatus, all may be arranged in close contact. desirable.

  The liquid crystal light valve 5 is connected to a liquid crystal light valve drive circuit (light modulation drive means) (not shown). The liquid crystal light valve drive circuit causes the liquid crystal light valve 5 to sequentially correspond to each incident color light. It has a structure that can be driven. Further, the projection type image display apparatus of the present embodiment is provided with a synchronization signal generation circuit (synchronization signal generation means) (not shown). The synchronization signal generation circuit generates a synchronization signal, and a light source drive circuit and a liquid crystal A structure capable of synchronizing the timing of emitting colored light from the LEDs 23, 24, and 25 of the LED group 22 and the timing of driving the liquid crystal light valve 5 corresponding to the colored light by inputting to the light valve driving circuit. It has become.

  That is, in the projection type image display apparatus of the present embodiment, one frame is time-divided, and R, G, B color lights are emitted sequentially from the LEDs 23, 24, 25 of the LED group 22, and the LEDs 23, 24 are emitted. , 25 to synchronize the timing of emitting the color light and the timing of driving the liquid crystal light valve 5, thereby driving the liquid crystal light valve 5 sequentially in time according to the color light emitted from each LED 23, 24, 25, By outputting an image signal corresponding to the color light emitted from each LED 23, 24, 25, it is possible to synthesize a color image.

  Specific numerical data is shown below. 4 is a plan view showing an example of the light emitting portion of the LED group 22. As shown in FIG. 4, one side of each LED (LED chip) 23, 24, 25 in the LED group 22 is 0.1 mm. Assume that four LEDs (one LED 23 (for red), two LEDs 24 (for green), and one LED 25 (for blue)) gather to have a 0.2 mm square light emitting part. When this light source is coupled to a tapered rod lens 31 having an incident end face of 0.2 mm square, an outgoing end face of 1 mm square, a distance between the incident end face and the outgoing end face of 6 mm, a side surface and a reflectivity of 100%. A calculation result is obtained that about 70% of the light rays emitted from the emission end face have a divergence angle of 15 degrees or less, and a very thin and highly directional lighting device can be obtained. Here, the shape of the side surface of each rod lens 31 is not a simple taper shape as shown in FIG. 2 but an appropriate curved surface as shown in FIG. 5, thereby further improving the coupling efficiency and improving the directivity. it can. By arranging the rod lenses 31 in a 4 × 6 array, an illumination device for the liquid crystal light valve 5 of about 0.3 inches is obtained. By attaching an appropriate projection lens 6 to this, it is possible to provide a projection module that can be incorporated into a portable device such as a mobile phone or a notebook computer.

  Further, it has been confirmed that a mold having a fine array structure such as the rod lens array 3 described above can be processed by using a recent precision processing machine (for example, FANUC: Robo Nano α-0iB). Yes.

[Example 2]
Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, another example of a color sequential drive type projection type image display apparatus is shown. FIG. 6 is a schematic configuration diagram showing the overall configuration of the projection-type image display apparatus, in which reference numeral 1 denotes an optical element, 2 denotes an LED array (planar light source), 3 denotes a rod lens array (uniform illumination means), 5 is a liquid crystal light valve (light modulation means), 6 is a projection lens (projection means), and 7 is a screen. In the present embodiment and the first embodiment, the configurations of the emission end portions of the LED array 2 of the optical element 1 and the rod lens array 3 are different. Details of the LED array 2 and the rod lens array 3 up to the emission end are shown in FIG.

  First, as shown in FIG. 7, a reflective surface 26 is formed on the back surface of each LED group 22 of the LED array 2. This may be formed by vapor deposition of a metal film or vapor deposition of a dielectric multilayer film, but the LED substrate 21 itself may be formed of metal and the peripheral portion of the LED group 22 may be mirror-finished.

Next, a reflective polarizer 41 is formed on the surface of the emission end face 33 of the rod lens array 3. The structure of the polarizer 41 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 33 of the rod lens array 3 molded of glass, and a stripe-like periodic structure is formed by etching. For example, the high refractive index material is TaO ₅ (refractive index: n≈2.2), the low refractive material is SiO ₂ (refractive index: n≈1.44), and the stripe structure pitch p, Filling Factor (land width Δ) / Pitch p) and the layer thickness L are optimized to function as a reflective polarizer that transmits p-polarized light and reflects s-polarized light. Here, by selecting a material having a higher refractive index of a high refractive index material and increasing the number of layers, a structure having a function of a reflective polarizer in a wider wavelength range can be created. In addition, a large number of ribs (light reflectors) made of a metal having light reflectivity such as aluminum are formed on the emission end face 33 of the rod lens array 3 at a pitch smaller than the wavelength of incident light instead of the dielectric multilayer film. May be. In this case as well, it can be formed by depositing a metal thin film on the emitting end face 33 of the rod lens array 3 and etching it in the same manner as the dielectric film.

  With this configuration, the light emitted from the LEDs 23, 24, and 25 of the LED group 22 is coupled to the rod lens array 3, and then internally reflected by the rod lenses 31 to be repeatedly emitted. To reach. At this time, one polarization component passes through the reflective polarizer 41 as it is and is directed to the liquid crystal light valve 5 by the reflective polarizer 41 formed on the emission end face 33 of the rod lens array 3. The polarization component in the direction orthogonal thereto is reflected by the reflective polarizer 41 and returns to the direction of the LED group 22, is reflected by the back surface and the peripheral reflecting surface 26 of the LED group 22, and repeats internal reflection by each rod lens 31 again. It reaches the emission end face 33. Since the polarization direction of these light beams is rotated by reflection in the rod lens a plurality of times, a part of the light is transmitted by the reflective polarizer 41 toward the liquid crystal light valve 5. This is repeated many times, and illumination light having a uniform polarization direction can be obtained with high utilization efficiency. The configuration and operation after the liquid crystal light valve 5 are the same as those in the first embodiment.

[Example 3]
Next, a third embodiment of the present invention will be described with reference to FIG. This embodiment is also a color sequential drive type projection display device, but the light valve is different from the liquid crystal type in that a mirror type is used. FIG. 9 is a schematic configuration diagram showing the overall configuration of the projection-type image display device, in which reference numeral 1 denotes an optical element, 2 denotes an LED array (planar light source), 3 denotes a rod lens array (uniform illumination means), Reference numeral 8 denotes a deflecting prism, 9 denotes a mirror type light valve (light modulation means), and 6 denotes a projection lens (projection means).

Since the configuration and operation of the portion (illumination device) of the optical element 1 from the LED array 2 to the rod lens array 3 are the same as those in the first or second embodiment, the description thereof is omitted here.
In FIG. 9, the light beam emitted from the rod lens array 3 is incident on the deflecting prism 8 in which two triangular prisms 81 and 82 are configured to have an air layer, and is totally reflected by the inclined surface 84 of the triangular prism 81 to be mirrored. The light enters the mold light valve 9 at a predetermined angle. The mirror type light valve 9 can be a mirror array formed by a semiconductor process as a pixel switching element. In general, a digital mirror device (DMD) manufactured by Texas Instruments is well known. For example, in the off state, the mirror tilt is zero degrees and is not coupled to the projection lens 6, but in the on state, the mirror has a predetermined tilt so that the light beam is reflected in the direction of the projection lens 6. The triangular prism 81 deviates from the total reflection condition of the inclined surface 83, passes through the deflecting prism 8, and forms an image on a screen (not shown) by the projection lens 6. When the mirror type light valve 9 is used as the light modulation means as in this embodiment, a configuration without using polarized light can be adopted, so that it is not always necessary to perform polarization conversion, and illumination light can be effectively guided to the projection lens 6. Therefore, it is possible to provide a bright projection type image display device with high light utilization efficiency.

[Example 4]
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a schematic configuration diagram showing the overall configuration of the projection-type image display device, in which reference numeral 1 denotes an optical element, 2 denotes an LED array (planar light source), 3 denotes a rod lens array (uniform illumination means), 4 is a polarizer, 5 is a liquid crystal light valve (light modulation means), and 6 is a projection lens (projection means). The schematic configuration of the projection type image display apparatus of the present embodiment is the same as that of FIG. 1, but the configuration of the rod lens array 3 of the optical element 1 is different. Light emitted from the LEDs 23, 24, and 25 of the LED group 22 is coupled to the rod lens 31 from the entrance opening of the rod lens array 3. The coupled light beam repeatedly undergoes internal reflection at each rod lens 31, and the illuminance is made uniform when it is emitted from the emission end face. Light rays emitted from the rod lens array 3 are incident on the liquid crystal light valve 5 with the polarization direction being aligned in one direction by the polarizer 4. The subsequent steps are the same as in the first embodiment.

  In the rod lens 31 of the embodiments so far, the light guide portion is filled with a medium. However, in the rod lens array 3 of the present embodiment, the portion of each rod lens 31 (light guide portion) is hollow. Therefore, the rod lens 31 can be made of not only a transparent resin but also a metal. That is, the hatched portion of the rod lens array 3 in FIG. 10 can be formed of metal, and the tapered hollow portion can be used as the rod lens 31. In that case, there is an advantage that a reflecting surface can be easily formed by mirror-treating the side surface (metal surface) 35 of the rod lens 31. Also, when molding with resin, there is an advantage that the mold can be easily created without using the above-mentioned precision processing machine. Specifically, a die can be created by making a tapered blade and cutting the die with the blade.

[Example 5]
Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 12 is a schematic configuration diagram showing the overall configuration of the projection type image display device, in which reference numeral 1 denotes an optical element, 2 denotes an LED array (planar light source), 3 denotes a rod lens array (uniform illumination means), Reference numeral 6 denotes a projection lens (projection means). In this embodiment, the rod lens 31 and the LED group 22 exist as many as the number of pixels that form an image. For example, there are about 300,000 VGA images (640 × 480). Each LED element in each LED group 22 (LED (red) 23, LED (green) 24, LED (blue) 25 capable of emitting each color light of R, G, B) described above) is a light source driving circuit (not shown). Connected to the (light source driving means), the light emission amount of each LED 23, 24, 25 is controlled corresponding to the image signal, is mixed in each rod lens 31, and the color light of the corresponding pixel is emitted to produce a color image. Can be synthesized. That is, the optical element 1 itself has a light modulation means. Then, the image is formed on a screen (not shown) by the projection lens 6.
In the configuration in which the light emitting means (LED group) 22 of the optical element 1 is a light modulation means as in this embodiment, a separate light modulation means is not required, and a configuration that does not use polarized light can be employed. Since there is no need for polarization conversion and it is not necessary to emit light sequentially in time, it is possible to provide a bright projection type image display apparatus with a small number of parts and high light utilization efficiency.

As described above based on the embodiments, in the present invention, as shown in FIGS. 1 to 9, a light source (LED group) composed of semiconductor light emitting devices (LEDs) 23, 24, and 25 and having a plurality of colors as one set. ) 22 are arranged in an array, and the emitted light from each light source is made uniform by the single rod lens 31 to make the emitted light end surface 33 of the rod lens array 3 uniform the illuminance for each color light. Therefore, it is possible to obtain an optical element and a lighting device that are small, thin, light, and have uniform illuminance on the light valve 5 (or 9).
In the present invention, as shown in FIG. 1 and FIG. 2, light sources (LED groups) 22 composed of semiconductor light emitting devices (LEDs) 23, 24 and 25, each having a plurality of colors as a set, are arranged in an array. The light emitted from each light source is made uniform by the single tapered rod lens 31 so that the illuminance is uniform for each color light at the light emitting end face 33 of the rod lens array 3, and the light emission is small and thin. An optical element and an illuminating device having a small angle and uniform illuminance on the light valve 5 (or 9) can be obtained.
Furthermore, in the present invention, as shown in FIG. 10, the rod lens array 3 is formed of a hollow rod lens, thereby facilitating mold creation. In addition to a transparent member such as glass or resin, a metal can be used, and the selectivity of the material can be expanded.

In the present invention, in addition to the above configuration, as a light source including a plurality of colors as a set, at least three of R, G, and B are set as a set, thereby providing an illumination device capable of full color.
In the present invention, as shown in FIG. 3, the space between the light source (LED group) 22 and the rod lens 31 is filled with a member 34 that is transparent to the light source light. The efficiency of extracting light from the LEDs 23, 24, and 25 of the LED group 22 can be improved by eliminating the total reflection at the interface.
Furthermore, in the present invention, by forming a film or structure that reflects the light source light on the side surface of the rod lens 31, the light beam incident on the side surface of the rod lens at a small angle is kept in the rod lens, thereby improving the light utilization efficiency. Can do.

In the present invention, the polarizer 4 is installed on the exit end face 33 side of the rod lens array 3 of the optical element, and is applied as an illuminating device for an image display device using the light valve 5 made of liquid crystal by aligning the polarized light. can do.
Further, in the present invention, by using a reflective polarizer as the polarizer, the light beam that has not passed through the polarizer can be returned to the rod lens and reused, and the light utilization efficiency can be improved. .
Furthermore, in the present invention, as shown in FIGS. 6 and 7, the optical element and the illumination device can be made thinner by forming the polarizer 41 directly on the emission end face 33 of the rod lens array 3.

In the present invention, in addition to the above configuration, the rod lenses 31 of the rod lens array 3 are integrally molded, so that productivity can be increased and costs can be reduced.
In the present invention, the light source arranged on the first surface side of each rod lens 31 of the rod lens array 3 has a light quantity ratio for obtaining a desired white balance, so that a good white balance can be obtained. it can.
Furthermore, in the present invention, since the light source (LED group 22) is arranged on the single substrate 21, the productivity can be increased and the cost can be reduced.

In the present invention, in addition to the above configuration, the same electrode of the light source that emits the same color is connected on the substrate 21, whereby the wiring of the light source can be simplified.
In the present invention, the first surface and the second surface of each rod lens 31 of the rod lens array 3 or the surface connecting the first opening and the second opening is curved as shown in FIG. By making this curved surface an appropriate curved surface, light having a large divergence angle can satisfy the total reflection condition, and the light utilization efficiency can be improved without forming a reflective film or structure on the side surface of the rod lens. Moreover, the emission angle from the rod lens 31 can be made narrower.
Furthermore, in the present invention, by providing the above configuration, it is possible to obtain a lighting device that is excellent in light utilization efficiency, can be reduced in size, reduced in thickness, and reduced in weight with a simple configuration, and has uniform illuminance.

The present invention includes an illuminating device having the above-described configuration and effects, and light modulation means (such as the liquid crystal light valve 5 or the mirror type light valve 9) that modulates light emitted from the illuminating device according to image information. Thus, it is possible to realize a small, thin, and light image display device that is excellent in light use efficiency, and further to realize a small, thin, and light projection image display device by providing a projection lens. it can.
Furthermore, in the present invention, by including the optical element having the above-described configuration and a modulation light-emitting means for modulating and emitting the light source of the optical element according to image information, the light use efficiency is excellent, and the size and thickness are reduced with a simple configuration. Thus, an image display device capable of reducing the weight and forming an image can be obtained. Further, by providing a projection lens, a projection image display device that is small, thin, and lightweight can be realized.
Further, the image display device of the present invention is not limited to a projector or the like, and can be applied to a rear projection type thin and light projection television or the like, and is not limited to a projection type and is also applied to an image display device such as a head mounted display. can do. Furthermore, since the image display device of the present invention is small, thin, lightweight, and has excellent light utilization efficiency, it can be used in portable devices such as mobile phones, portable game machines, digital cameras, electronic notebooks, electronic books, and notebook computers. It can be built in equipment.

The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, as the planar light source, a semiconductor laser, an organic EL element, an inorganic EL element, or the like can be used in addition to the LED.
In addition, the number of light emitting elements (LEDs, etc.) of each color in each light source is not limited to one red, two greens, and one blue. Therefore, each color can be configured with an appropriate number of elements.

It is a schematic block diagram of the projection type image display apparatus which shows one Example of this invention. It is a schematic principal part sectional drawing of the projection type image display apparatus shown in FIG. It is a figure which shows the detail of the connection part of the LED array of a projection type image display apparatus shown in FIG. 1, and a rod lens array. It is a top view which shows an example of the light emission part of LED group. It is a schematic sectional drawing which shows another structural example of a rod lens array. It is a schematic block diagram of the projection type image display apparatus which shows another Example of this invention. It is a schematic principal part sectional drawing which shows the structural example of the LED array and rod lens array of a projection type image display apparatus shown in FIG. It is a schematic principal part perspective view which shows an example of the structure of the polarizer provided in the output end surface of the rod lens array shown in FIG. It is a schematic block diagram of the projection type image display apparatus which shows another Example of this invention. It is a schematic block diagram of the projection type image display apparatus which shows another Example of this invention. It is a schematic block diagram of the projection type image display apparatus which shows an example of a prior art. It is a schematic block diagram of the projection type image display apparatus which shows another Example of this invention. (A) is a schematic perspective view showing another main configuration example of the rod lens array, and (b) is a cross-sectional view showing a shape example of one rod lens of the rod lens array. It is the graph which showed the length of the rod lens on a horizontal axis, and the ratio of the light ray by which a divergence angle is coupled within 15 degrees on a vertical axis.

Explanation of symbols

1: Optical element 2: LED array (planar light source)
3: Rod lens array (uniform illumination means)
4: Polarizer 5: Liquid crystal light valve (light modulation means)
6: Projection lens (projection means)
7: Screen 8: Deflection prism 9: Mirror type light valve 21: Substrate 22: LED group (light source)
23, 24, 25: LED (light emitting element)
26: Reflecting surface 31: Rod lens 32: Incident end surface (first surface)
33: Output end face (second face)
34: Transparent resin 41: Reflective polarizer

Claims (19)

A light source composed of a semiconductor light-emitting device capable of emitting a plurality of color lights and selectively emitting desired elements, and a set of a plurality of colors;
The first surface is made of a member transparent to the light from the light source, and has a first surface having an area equal to or larger than the light emitting portion area of the light source, and a second surface facing the first surface. A rod lens array in which rod lenses having the two surfaces as a bottom surface are two-dimensionally arranged;
In an optical element consisting of
An optical element, wherein a light source composed of a semiconductor light emitting device having the plurality of colors as a set is disposed on a first surface side of each rod lens of the rod lens array. A light source composed of a semiconductor light-emitting device capable of emitting a plurality of color lights and selectively emitting desired elements, and a set of a plurality of colors;
The first surface is made of a member that is transparent to the light from the light source, has a first surface having an area equal to or larger than the light emitting area of the light source, and has a larger area than the first surface. A rod lens array having a second surface facing the surface and two-dimensionally arranged rod lenses having the two surfaces as a bottom surface;
In an optical element consisting of
An optical element, wherein a light source composed of a semiconductor light emitting device having the plurality of colors as a set is disposed on a first surface side of each rod lens of the rod lens array. A light source composed of a semiconductor light-emitting device capable of emitting a plurality of color lights and selectively emitting desired elements, and a set of a plurality of colors;
A first opening surface having an area equal to or greater than the area of the light source, and a second opening surface having an area larger than the first opening surface and facing the first surface; A film or structure for reflecting light source light is formed on the side surface of the hollow rod lens having the two opening surfaces as the bottom surface, and a rod lens array in which the hollow rod lenses are two-dimensionally arranged;
In an optical element consisting of
An optical element, wherein a light source composed of a semiconductor light-emitting device having the plurality of colors as a set is disposed on a first opening surface side of each hollow rod lens of the rod lens array. The optical element according to any one of claims 1 to 3,
An optical element, wherein the light source composed of a semiconductor light emitting device having a set of a plurality of colors is a light source composed of a semiconductor light emitting device having at least three colors of red, green, and blue. The optical element according to claim 1 or 2,
An optical element characterized in that a space between the light source and the rod lens is filled or bonded by a member transparent to the light from the light source. The optical element according to any one of claims 1 to 3,
An optical element, wherein a film or a structure that reflects light from the light source is formed on a side surface of the rod lens that is a surface connecting the first surface and the second surface of the rod lens. The optical element according to any one of claims 1 to 6,
An optical element comprising a polarizer disposed on the second surface side of the rod lens array. The optical element according to claim 7.
An optical element, wherein the polarizer is a reflective polarizer. The optical element according to claim 8.
The optical element, wherein the polarizer is formed on a second surface of the rod lens array. The optical element according to any one of claims 1 to 9,
Each rod lens of the rod lens array is molded integrally. The optical element according to any one of claims 1 to 10,
An optical element characterized in that a light source arranged on the first surface side of each rod lens of the rod lens array has a light quantity ratio for obtaining a desired white balance. The optical element according to any one of claims 1 to 11,
An optical element, wherein the light source is disposed on a single substrate. The optical element according to any one of claims 1 to 12,
An optical element characterized in that the same electrode of a light source emitting the same color is connected. The optical element according to any one of claims 1 to 13,
The optical element, wherein the first surface and the second surface of each rod lens of the rod lens array or the surface connecting the first opening and the second opening is a curved surface.   An illuminating device using the optical element according to any one of claims 1 to 14.   16. An image display device comprising: the illumination device according to claim 15; and light modulation means for modulating light emitted from the illumination device according to image information.   16. An image comprising: the illumination device according to claim 15; a light modulation unit that modulates light emitted from the illumination device according to image information; and a lens that magnifies and projects the modulated light. Display device.   15. An optical element according to claim 1, and a modulation light emitting means for modulating and emitting a light source of the optical element according to image information, and each rod lens of a rod lens array of the optical element. An image display device characterized in that the light output from the pixel is an output of one pixel.   19. An image display device comprising: the image display device according to claim 18; and a lens for enlarging and projecting an image of the image display device.

Images