JP2002228973A - Image projection device - Google Patents

Abstract

(57) [Problem] To provide an image projection device capable of improving the utilization efficiency of irradiation light emitted from a light source. A light source configured by arranging a plurality of light-emitting diodes in an array, a polarization conversion element for aligning the polarization direction of light emitted from the light source with a first polarization direction, and polarization by the polarization conversion element The liquid crystal display device includes a liquid crystal display device that receives light whose direction is aligned with the first polarization direction, and a projection lens that projects light emitted from the liquid crystal display device onto a screen. The polarization conversion element has a plurality of sets of a polarization beam splitter, a reflection element, and a half-wave plate, and a plurality of sets of the polarization beam splitter, the reflection element, and the half-wave plate have an array period. Are equal to the arrangement cycle of the light emitting diodes arranged in the array in one direction, and are arranged so that the directions thereof coincide with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image projection device for projecting an image displayed on a liquid crystal display device onto a screen by means of a projection lens, and more particularly, to improving the efficiency of use of light emitted from a light source. Regarding effective technology.

[0002]

2. Description of the Related Art As a conventional image projection apparatus, a lamp such as a halogen lamp or a metal halide lamp is used as a light source, and an image displayed on a transmission type or reflection type liquid crystal display device (hereinafter, referred to as an LCD panel) is projected on a projection lens. There is known an apparatus for projecting an image on a screen. Further, for example, as described in JP-A-11-32278, JP-A-10-33599, and JP-A-10-301201, a light emitting diode (hereinafter, referred to as an LED).
There is also known an image projection apparatus which uses an image as a light source to reduce the size of the apparatus. Among them, Japanese Patent Application Laid-Open No. H11-32278 discloses a light emitting diode (LE) that emits red, blue, and green light.
D) has a light source (hereinafter, referred to as an LED array light source) arranged in an array and one LCD panel, and periodically switches light emission of each color LED, and performs spatial light modulation of the LCD panel in synchronization with this. An image projection device capable of time-division color display is described.

As an example of these prior arts, FIG. 12 shows an image projection apparatus constituted by an LED array light source, a polarizing beam splitter, a reflective LCD panel and a projection lens. In the image projection device shown in FIG. 12, the LED array light source 1 is configured by arranging LEDs that emit red, green, and blue light in an array. Red, blue and green LEDs
The emission color is periodically switched in synchronization with an image signal input to the reflection type LCD panel 4. LED array light source 1
The emitted light enters the polarization beam splitter 3. Of the incident light, only light having a polarization component in the x direction (perpendicular to the paper) shown in FIG. 12 is reflected by the polarization beam splitter 3 and is incident on the reflection type LCD panel 4. The light incident on the reflective LCD panel 4 is reflected with its polarization state modulated based on the image signals of the respective colors that are periodically input. The modulated reflected light is detected by the polarization beam splitter 3 and projected on a screen (not shown) by the projection lens 5.

[0004]

In the above-mentioned conventional image projection apparatus, as shown in FIG.
Is non-polarized, light having a polarization component in the x direction (perpendicular to the paper) is reflected by the beam splitter 3 and enters the reflective LCD panel 4, but the remaining half of the light amount is z. The light having the polarization component in the direction passes through the polarization beam splitter 3 and does not enter the reflection type LCD panel 4. That is, in the conventional image projection device,
There is a problem that the utilization efficiency of light emitted from the LED array light source 1 is low. In particular, as shown in FIG. 12, when one LED array light source 1 and one LCD panel 4 are used, the size of an image projection apparatus using three LED array light sources and three LCD panels can be further reduced. Yes, but one LC
Since red, blue, and green light emitted in time series is incident on the D panel, the emission time of each color can be obtained only about 1/3 of that when three LCD panels are used. Is also about 1/3.

Further, when one LED array light source 1 is used, only about one third of the light source area of an image projection apparatus that combines the light emitted from the three LED array light sources with a dichroic prism can be obtained. Has also been reduced to 1/3, and further improvement in light use efficiency has been an issue. SUMMARY An advantage of some aspects of the invention is to improve the efficiency of use of irradiation light emitted from a light source in an image projection device. To provide technology. The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0006]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows. That is, the present invention provides a light source configured by arranging a plurality of light emitting diodes in an array, a polarization conversion element for aligning the polarization direction of light emitted from the light source with a first polarization direction, and the polarization conversion element. And a projection lens for projecting light emitted from the liquid crystal display device onto a screen. The liquid crystal display device receives light whose polarization direction is aligned with the first polarization direction. According to the above-described means, the unpolarized light emitted from the light source is
Since the light is incident on the liquid crystal display device while being aligned in the first polarization direction by the polarization conversion element, all the light emitted from the light source can be used, so that the light use efficiency can be improved. It becomes possible.

In a preferred embodiment of the present invention, the polarization conversion element comprises: a polarization beam splitter; a reflection element;
A plurality of sets of a half-wave plate are provided, and the plurality of sets of the polarizing beam splitter, the reflection element, and the half-wave plate are arranged in one direction of a light emitting diode in which an arrangement cycle is arranged in the array. Are arranged so as to be equal to the arrangement period and to have the same direction. In a preferred embodiment of the present invention, the polarization conversion element is provided for each light-emitting diode, and allows light having a first polarization direction of light emitted from each light-emitting diode to pass through and enter the liquid crystal display device. A plurality of polarization beam splitters for reflecting light in a second polarization direction; and a plurality of reflection elements provided for each of the light emitting diodes, for reflecting light in the second polarization direction reflected by the polarization beam splitter. A plurality of light emitting diodes provided for each of the light emitting diodes, for converting the light of the second polarization direction reflected by the plurality of reflection elements into light of the first polarization direction, and causing the light to enter the liquid crystal display device. 1/2
And a wave plate.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments, components having the same functions are denoted by the same reference numerals, and repeated description thereof will be omitted. [First Embodiment] FIG. 1 is a sectional view showing a schematic configuration of an image projection apparatus according to a first embodiment of the present invention. The image projection apparatus according to the present embodiment includes an LED array light source 1, a polarization conversion element 2, a polarization beam splitter 3, a reflective LCD panel 4, and a projection lens 5. As shown in FIG. 2, the LED array light source 1 includes an LED that emits red light (R in the figure), an LED that emits green light (G in the figure), and an LED that emits blue light (B in the figure). Are alternately arranged two-dimensionally (that is, in a matrix). Further, as shown in FIG. 2, the arrangement period of each LED in the x direction is T. Also,
The red, green, and blue LEDs emit light in time series in synchronization with the red, green, and blue image signals input to the reflective LCD panel 4.

The light emitted from the LED array light source 1 is
As shown in FIG. 1, the light passes through the polarization conversion element 2. The polarization conversion element 2 has a function of converting incident non-polarized light emitted from the LED array light source 1 into one polarized light component and emitting the same. In other words, as shown in FIG. 3A, the P-polarized light component incident on the polarization conversion element 2 is emitted as P-polarized light as it is, and the S-polarized light component is converted to P-polarized light and emitted. As shown in b), the S-polarized light component incident on the polarization conversion element 2 has the function of being emitted as it is as S-polarized light, and the P-polarized light component has the function of being converted into S-polarized light and emitted. Note that, in the present invention, the first polarization direction is the polarization direction that is emitted as it is without being converted in the polarization conversion element 2 (for example, the p-polarization component in FIG. b) means s-polarized light component), and the second
Means the polarization direction converted and emitted by the polarization conversion element 2 (for example, the s-polarized light component in FIG. 3A and the p-polarized light component in FIG. 3B).

FIG. 4 is a sectional view showing an example of the polarization conversion element 2 shown in FIG. The polarization conversion element 2 shown in FIG. 4 has a plurality of sets of a polarization beam splitter 21, a mirror 22, and a half-wave plate 23. In FIG. 4, three sets of the polarization beam splitter 21 and the mirror 22 are provided. And the half-wave plate 23
It is illustrated. The cycle (Ta) in the x direction is the LED
The arrangement of the LEDs of the array light source 1 is equal to the arrangement period (T) in the x direction, and the center of each LED is aligned with the center of the polarizing beam splitter 21. The inclination (θ in FIG. 4) of the polarizing beam splitter 21 and the mirror 22 is set to approximately 45 degrees. By arranging the polarization beam splitter 21, the mirror 22, and the half-wave plate 23 in this manner, a large amount of light emitted from each LED can be incident on the polarization beam splitter 21.

Each LED of the LED array light source 1
The emitted light is unpolarized light and has a polarized light component P oscillating in the x direction and a polarized light component S oscillating in the z direction. Among them, the polarization component P transmits through the polarization beam splitter 21. On the other hand, the polarization component S is
After being reflected by the mirror 22, the light is reflected by the mirror 22, is reflected by the mirror 22, enters the half-wave plate 23, and is emitted after the polarization direction is changed from S to P. In other words, the light emitted from each LED of the LED array light source 1 that has passed through the polarization conversion element 2 has its polarization component aligned with the P component (x direction). Therefore, as shown in FIG. 1, all of the light emitted from the polarization conversion element 2 with the polarization directions aligned in the x direction enters the polarization beam splitter 3, is reflected by the polarization beam splitter 3, and is reflected by the reflection type LCD panel. 4 is incident. Reflective LCD
The light incident on the panel 4 is reflected after its polarization state is modulated based on the image information of each color of red, green and blue. Of the reflected light, light projected as an image passes through the polarizing beam splitter 3 and is projected by a projection lens 5 on a screen (not shown).

Next, an example of a method for manufacturing the polarization conversion element 2 shown in FIG. 4 will be described. First, as shown in FIG. 5A, a plurality of mirrors 22 and a polarizing beam splitter 21 formed on the surface of a glass substrate 24 are manufactured.
The mirror 22 is formed on a glass substrate 24 by subjecting silver (Ag), aluminum (Al), or the like to vacuum evaporation. The polarizing beam splitter 21 is formed of a multilayer film in which thin films having a high refractive index and thin films having a low refractive index are alternately stacked on a glass substrate 24 by vacuum evaporation or sputtering.
At this time, the glass used for the polarizing beam splitter,
Thin film of high refractive index, the refractive index of a thin film of low refractive index, respectively n _g, n _H, When n _L, n _g = l. 62, _nH = 2.0
4 (ZiO ₂ ), n _L = 1.385 (MgF ₂ ), _ng =
l. _{70, n H = 2.44 (TiO} 2), n L = 1.38
5 (MgF ₂ ). Next, FIG.
As shown in (b), the mirror 22 and the glass substrate 24 on which the polarization beam splitter 21 is formed are alternately overlapped and adhered.

As the adhesive, an epoxy resin-based adhesive, an ultraviolet curable adhesive, or the like is used. Epoxy resin adhesives are two-part adhesives, and are classified into a room-temperature curing type and a heat-curing type. The UV-curable adhesive is a one-liquid type and can be bonded in a short time by irradiating ultraviolet rays. After the adhesive has hardened, the portion indicated by the wavy line in FIG.
(A). In addition, as shown in FIG.
By bonding the half-wave plate 23, the polarization conversion element 2 can be produced. As a material of the half-wave plate 23,
A birefringent film (polyvinyl alcohol), crystalline quartz, or the like can be used.

As described above, in this embodiment, the polarization conversion element 2 is provided, and all the light emitted from the LED array light source 1 can be reflected by the polarization beam splitter 3 and made incident on the LCD panel 4. Therefore, the light utilization effect can be improved about twice as compared with the conventional image display device. In the above description, in order to perform the polarization conversion with high efficiency, the period of the polarization beam splitter 21, the mirror 22, and the half-wave plate 23 constituting the polarization conversion element 2 in the x direction of the LED array is changed. Equal to the array period T of
In addition, the case has been described where the LED center and the center of the polarization beam splitter 21 are arranged so as to coincide with each other. However, even when these periods do not match, the polarization conversion efficiency is reduced, but it goes without saying that there is an effect of improving the light use efficiency. Further, the mirror 22 shown in FIG. 4 may be replaced by a polarization beam splitter, that is, the polarization direction may be changed by the polarization beam splitter and the half-wave plate 23.

[Second Embodiment] FIG. 7 is a sectional view showing a schematic configuration of an image projection apparatus according to a second embodiment of the present invention.
In the first embodiment described above, the image projection device that guides the reflected light of the polarization beam splitter 3 to the reflective LCD panel 4 is used. In the present embodiment, as shown in the yz section of FIG.
The ED array 1 and the polarization conversion element 2 have a period T equal to the z direction.
This is an image projection device arranged so that In the present embodiment, light emitted from the LED array 1 and passing through the polarization conversion element 2 has a polarization component in the z direction. Therefore, the light that has passed through the polarization conversion element 2 passes through the polarization beam splitter 3 and enters the reflective LCD panel 4. In this arrangement, the polarization beam splitter 21 and the mirror surface 22 constituting the polarization conversion element 2 are parallel to the plane of the polarization beam splitter 3.

Therefore, the light having passed through the polarization conversion element 2 has a polarization component in the z direction, passes through the polarization beam splitter 3, and reaches the reflection type LCD panel 4. Reflective type L
The light that has entered the CD panel 4 is reflected after its polarization state has been modulated based on the image information of the colors of the red, green, and blue regions.
Of the reflected light, the light projected as an image passes through the polarizing beam splitter 3 and is projected by a projection lens 5 on a screen (not shown). As described above, also in the present embodiment, the polarization conversion element 2 is provided, and all the light emitted from the LED array light source 1 can be transmitted through the polarization beam splitter 3 and made incident on the LCD panel 4. As compared with the image display device described above, the light utilization effect can be improved about twice.

Third Embodiment FIG. 8 shows an LED array light source 1 used in an image projection apparatus according to a third embodiment of the present invention.
It is a front view which shows schematic structure of. In each of the embodiments described above, the image projection apparatus uses the LED array light source 1 in which the LEDs that emit red, green, and blue light are respectively arranged in a dispersed manner. Array light source 1
An image display device using LEDs in which light emitting elements of three colors are packaged on one chip. As shown in FIG. 8, in the present embodiment, the arrangement cycle of the LED array is a cycle (T) or (T ′) in which chips having three LEDs (R, G, B) are arranged. By arranging them so as to coincide with the arrangement cycle of the polarization beam splitter 21, the mirror 22, and the half-wave plate 23 in the polarization conversion element 2, an image projection device with high light use efficiency can be obtained.

[Fourth Embodiment] FIG. 9 is a sectional view showing a schematic configuration of an image projection apparatus according to a fourth embodiment of the present invention.
In each of the above embodiments, the reflection type L is used as the LCD panel.
Although the image projection apparatus uses a CD panel, the present embodiment is an image projection apparatus using a transmissive LCD panel as an LCD panel. In the present embodiment, as shown in FIG. 9, an LED array light source 1, a polarization conversion element 2,
Transmissive LCD panel 4T, polarizing plate 6, projection lens 5
Composed of Light emitted from the LED array light source 1 and having passed through the polarization conversion element 2 is incident on the transmissive LCD panel 4T with its polarization direction aligned in one direction. The light incident on the transmissive LCD panel 4T has its polarization state modulated based on the image information of each of the red, green, and blue colors, and the transmissive L
The light passes through the CD panel 4T and enters the polarizing plate 6. The polarizing plate 6 transmits light projected as an image out of the incident light,
The other light is arranged to absorb the light, and the light transmitted through the polarizing plate 6 is projected on a screen (not shown) by the projection lens 5. As described above, also in the present embodiment, the polarization conversion element 2 is provided, and all the light emitted from the LED array light source 1 can be made incident on the transmission type LCD panel 4T. Thus, the light utilization effect can be improved about twice.

[Fifth Embodiment] FIG. 10 is a sectional view showing a schematic configuration of an image projection apparatus according to a fifth embodiment of the present invention. In each of the above-described embodiments, the image projection device has one LED array light source 1, but this embodiment is an image projection device using a plurality of LED array light sources. As shown in FIG. 10, the image projection apparatus according to the present embodiment includes an LED array light source 1R that emits red light, an LED array light source 1G that emits green light, and an LED that emits blue light.
Array light source 1B and three polarization conversion elements (2R, 2G,
2B), a dichroic prism 7 for synthesizing red, blue, and green light, a polarizing beam splitter 3, and a reflective LCD
It comprises a panel 4 and a projection lens 5. The red light emitted from the LED array light source 1R is
Can align the polarization direction in the x direction. Similarly, LED
The green light emitted from the array light source 1G is polarized by the polarization conversion element 2G in the x direction so that the LED array light source 1B
The direction of polarization of the emitted blue light is aligned in the x direction by the polarization conversion element 2B.

The red light emitted from the polarization conversion elements (2R, 2G, 2B) with their polarization directions aligned in the x direction,
The green and blue lights enter the dichroic prism 7.
The red and blue lights are reflected by the dichroic prism 7 and enter the polarization beam splitter 3, and the green light passes through the dichroic prism 7 and enters the polarization beam splitter 3. After being incident on the polarizing beam splitter 3,
The way red, green, and blue light travel is the same as in the first embodiment, and a detailed description thereof will be omitted. in this way,
Also in the present embodiment, the polarization conversion element (2R, 2G, 2B)
And all the light emitted from the LED array light sources (1R, 1G, 1B) can be reflected by the polarization beam splitter 3 and made incident on the reflection type LCD panel 4, so that there is no need for a conventional image display device. Thus, the light utilization effect can be improved about twice. Further, in the present embodiment, the light source area (3 times) is three times larger than that of the first embodiment.
Light sources), so that the amount of light emitted from the projector is 3
Can be twice as high. On the other hand, dichroic prism 7 and LED array light source (1R, 1G, 1B)
Since the number of light sources is required, the size of the image projection device increases.

[Embodiment 6] FIG. 11 is a sectional view showing a schematic configuration of an image projection apparatus according to Embodiment 6 of the present invention. In each of the embodiments described above, the image projection apparatus has one LCD panel.
This is an image projection device using a CD panel. As shown in FIG. 11, the image projection apparatus according to the present embodiment includes an LED array light source 1R that irradiates red, an LED array light source 1G that irradiates green, an LED array light source 1B that irradiates blue, and a polarization conversion element. (2R, 2G, 2B), a transmissive LCD panel (4TR, 4TG, 4TB), and a polarizing plate (6R, 6G,
6B) and a dichroic mirror 7R that reflects red light
, A dichroic mirror 7G that reflects green light, a dichroic mirror 7B that transmits blue light, and a projection lens 5.

The polarization direction of the red light emitted from the LED array light source 1R is aligned by the polarization conversion element 2R.
The light enters the transmissive LCD panel 4TR. Transmissive LCD
The light that has entered the panel 4TR has its polarization state modulated based on the red image information, exits from the transmissive LCD panel 4TR, and enters the polarizing plate 6R. The polarizing plate 6R is arranged so that the light projected as an image out of the incident light is transmitted, and the other light is absorbed, and the red light transmitted through the polarizing plate 6R is reflected by the dichroic mirror 4R. Is transmitted through the dichroic mirror 4G, is reflected by the dichroic mirror 4B, and is projected by the projection lens 5 onto a screen (not shown). The polarization direction of the green light emitted from the LED array light source 1G is aligned by the polarization conversion element 2G, and is incident on the transmission type LCD panel 4TG. The light incident on the transmissive LCD panel 4TG has its polarization state modulated based on green image information, and
The light exits from the panel 4TG and enters the polarizing plate 6G.

The polarizing plate 6G is arranged so that the light projected as an image out of the incident light is transmitted and the other light is absorbed, and the green light transmitted through the polarizing plate 6G is transmitted to the dichroic mirror 4G. Is reflected by the dichroic mirror 4B and projected by the projection lens 5 onto a screen (not shown). The blue light emitted from the LED array light source 1B has its polarization direction aligned by the polarization conversion element 2B and is incident on the transmissive LCD panel 4TB. The light incident on the transmissive LCD panel 4TB has its polarization state modulated based on the blue image information, and
B exits and enters the polarizing plate 6B. The polarizing plate 6B is arranged so that the light projected as an image among the incident light is transmitted, and the other light is absorbed, and the blue light transmitted through the polarizing plate 6B is transmitted through the dichroic mirror 4B. , And projected onto a screen (not shown) by the projection lens 5.

As described above, also in this embodiment, the polarization conversion elements (2R, 2G, 2B) are provided, and the polarization directions of all the lights emitted from the LED array light sources (1R, 1G, 1B) are aligned. Transmissive LCD panel (4TR, 4TG, 4
TB), the light utilization effect can be improved about twice as compared with the conventional image display device. Further, in the present embodiment, the light source area (three light sources) is three times as large as that in the above-described first embodiment, so that the emission light amount of the projector can be tripled. In addition, red, green, and blue images are displayed on three transmissive LCDs.
Since the display is performed on the panel (4TR, 4TG, 4TB), the LEDs do not need to be turned on in time series, and the LED lighting time three times or more that of the first embodiment can be obtained. for that reason,
In the image projection device of the present embodiment, the amount of emitted light can be nine times higher than in the image projection device of the first embodiment.

On the other hand, dichroic mirrors (7R, 7
G, 7B) and three LED array light sources (1R, 1G,
1B) Since three LCD panels are required, the size of the image projection device increases. In each of the above-described embodiments, an image projection apparatus that projects a color image onto a screen, that is, an image projection apparatus that uses the LED array light source 1 that emits light of three colors, red, green, and blue, has been described. ,
The present invention is not limited to this, and it is needless to say that the present invention can be applied to an LED that emits white light or an image projection apparatus that projects a monochrome image using only one color LED. As described above, the invention made by the inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and can be variously modified without departing from the gist of the invention. Of course, it is.

[0026]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows. ADVANTAGE OF THE INVENTION According to the image projector of this invention, it becomes possible to improve the utilization efficiency of the irradiation light irradiated from a light source.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image projection device according to a first embodiment of the present invention.

FIG. 2 is a front view showing a schematic configuration of the LED array light source shown in FIG.

FIG. 3 is a diagram for explaining a conversion function of the polarization conversion element shown in FIG.

FIG. 4 is a sectional view showing an example of the polarization conversion element shown in FIG.

FIG. 5 is a diagram illustrating an example of a method for manufacturing the polarization conversion element illustrated in FIG.

FIG. 6 is a diagram illustrating an example of a method for manufacturing the polarization conversion element illustrated in FIG.

FIG. 7 is a cross-sectional view illustrating a schematic configuration of an image projection device according to a second embodiment of the present invention.

FIG. 8 is a front view showing a schematic configuration of an LED array light source used in the image projection device according to the third embodiment of the present invention.

FIG. 9 is a sectional view illustrating a schematic configuration of an image projection device according to a fourth embodiment of the present invention.

FIG. 10 is a sectional view illustrating a schematic configuration of an image projection device according to a fifth embodiment of the present invention.

FIG. 11 is a sectional view illustrating a schematic configuration of an image projection device according to a sixth embodiment of the present invention.

FIG. 12 is a cross-sectional view illustrating a schematic configuration of a conventional image projection apparatus.

[Explanation of symbols]

1 LED array light source, 1R LED array light source (red), 1G LED array light source (green), 1B LED
Array light source (blue), 2, 2R, 2G, 2B ... polarization conversion element, 3, 21, 31 ... polarization beam splitter, 4 ... reflection type liquid crystal display (LCD panel), 4T, 4TR, 4T
G, 4TB: transmissive liquid crystal display (LCD panel), 5
... Projection lens, 6, 6R, 6G, 6B ... Polarizer, 7 ... Dichroic prism, 7R, 7G, 7B ... Dichroic mirror, 22 ... Mirror, 23 ... 1/2 wavelength plate, 24
... a glass substrate.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 21/00 G03B 21/00 E 33/12 33/12 H04N 5/74 H04N 5/74 K 9/31 9/31 C (72) Inventor Kazutaka Tsuji 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Osamu Ebina 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Ltd.Digital Media Systems Division, Hitachi, Ltd. Address F-term in Hitachi Digital Media System Division (Reference) 2H049 BA05 BA06 BA42 BA43 BA47 BB03 BB43 BC22 2H088 EA13 EA14 EA15 EA16 HA13 HA15 HA18 HA20 HA21 HA24 HA28 KA05 MA06 2H091 FA05X FA07X FA08X FA10X FA11X FA11Z FA14Z FA26X FA26Z FA45X FA45Z KA01 LA16 MA07 5C058 BA05 EA11 EA13 EA26 EA51 5C060 BA03 GB08

Claims (3)

[Claims] A light source configured by arranging a plurality of light emitting diodes in an array; a polarization conversion element for aligning a polarization direction of light emitted from the light source with a first polarization direction; An image projection device, comprising: a liquid crystal display device that receives light whose polarization direction is aligned with a first polarization direction; and a projection lens that projects light emitted from the liquid crystal display device onto a screen. 2. The polarization conversion element has a plurality of sets of a polarization beam splitter, a reflection element, and a half-wave plate, and the plurality of sets of the polarization beam splitter, the reflection element, and 1
2. The half-wave plate according to claim 1, wherein the arrangement cycle is equal to the arrangement cycle in one direction of the light emitting diodes arranged in the array, and is arranged so that the directions coincide with each other. The image projection device according to claim 1. 3. The polarization conversion element is provided for each light emitting diode, passes light having a first polarization direction of light emitted from each light emitting diode, makes the light incident on the liquid crystal display device, A plurality of polarization beam splitters for reflecting light in the polarization direction; a plurality of reflection elements provided for each of the light emitting diodes, for reflecting light in the second polarization direction reflected by the polarization beam splitter; A plurality of half-wavelengths provided for each light emitting diode, convert the light in the second polarization direction reflected by the plurality of reflection elements into light in the first polarization direction, and make the light incident on the liquid crystal display device. And a plate.
An image projection device according to claim 1.