JP4943885B2 - Multi-wavelength polarization conversion element, illumination unit, and image display device - Google Patents

Description

  The present invention uses a multi-wavelength polarization conversion element that converts an arrayed non-polarized beam into an aligned polarized light beam, emits the same, an illumination unit using the multi-wavelength polarization change element, and the illumination unit. The present invention relates to an image display device such as a projector device or a projection television.

Conventionally, light beams of different wavelengths are incident on adjacent film portions of the polarization conversion element, and one is made to be P-polarized and the other is made to be S-polarized, and the in-plane illuminance distribution of the emitted light is made uniform. An illumination optical system and a projector using the illumination optical system have been proposed (see, for example, Patent Document 1).
In the invention described in Patent Document 1, a dichroic mirror having a size that covers the entire optical path between the first fly-eye lens and the second fly-eye lens of the liquid crystal projector device, and a reflection non-parallel thereto. A mirror is provided to divide the beam into green (G) and red (R) + blue (B), and the direction of the beam is shifted between the two wavelengths, so that the film adjacent to the polarization conversion element (reflection film and polarization separation film) (PBS film)), G is aligned with P-polarized light, R + B is aligned with S-polarized light, and G is aligned with the polarization beam splitter (PBS) of the color separation / combination optical system arranged in the subsequent stage. Is transmitted, R + B is reflected, and R and B are separated by a dichroic prism disposed downstream of the PBS to illuminate a reflective liquid crystal panel corresponding to each color.

  The above prior art aims to efficiently separate and guide light of a predetermined wavelength to the liquid crystal panel of each wavelength, but the light beam from the light source lamp is converted into green (G) color light and red light by a color light separation optical element. The light is separated into (R) + blue (B) color light and is not configured using a light emitting diode (LED). Therefore, it is different from the present invention aiming at densely arranging the LED arrays, and it is difficult to apply to a projector apparatus using an LED light source.

WO2003 / 001277 publication Special Table 2000-510961

In recent years, the light emission efficiency of light emitting diodes (LEDs) has been remarkably increased, and its use as an illumination light source has been activated. Although the development of indoor lighting, car headlamps, and the like has preceded, prototypes such as pocket projectors using LEDs as light sources have also been put to practical use in projectors.
However, when the LED is viewed as a light source of a projector device, there is no sense of insufficient light quantity. To replace the light source such as the current high-pressure mercury lamp, the LED itself has a higher output, as well as an optical system. It is necessary to overcome many hurdles, such as improvement of light utilization efficiency, increase in the number of arrays, and polarization conversion in a liquid crystal projector.
In view of the above, an object of the present invention is to improve the problem of polarization conversion that occurs when an LED is used as the light source of an image display device such as a liquid crystal projector device, and the number of arrays.

In general, in a projector apparatus (liquid crystal projector apparatus) provided with a liquid crystal as a light valve, a polarization conversion element is used to align the polarization direction of light emitted from the light valve. For example, the polarization conversion element is configured as shown in FIG. 21, and this polarization conversion element 100 includes a combination of a polarization separation film (PBS film) 101, a reflection film 102, and a half-wave plate 103 as one unit. In general, these are arranged in an array.
A non-polarized beam emitted from a light source (not shown) is condensed on the polarization conversion element 100 by the fly-eye lens 104 or the like, and a non-polarized beam incident on the polarization separation film 101 of the polarization conversion element 100 is reflected on the polarization separation film 101. Separated into a P-polarized beam (transmitted light) and an S-polarized beam (reflected light). The S-polarized beam is reflected by the reflecting surface 102 and becomes a beam parallel to the P-polarized beam. If the half-wave plate 103 is disposed on one of the optical paths of the P-polarized beam and the S-polarized beam, a beam with uniform polarization can be obtained.

  A similar effect can be obtained by using a polarization separation film (PBS film) instead of the reflection film. Since all the beams reflected from the polarization separation film are S-polarized light, the PBS film can be used as a reflection function film because the PBS film reflects all the beams even if the PBS film is used instead of the reflection film.

  However, transmitted light cannot be incident on the PBS film used as the reflective function film. This is because when reflected light and transmitted light are incident on the same PBS film part, P-polarized light and S-polarized light are mixed in the subsequent stage of the PBS film, and the polarized light is not separated. Therefore, in the conventional polarization conversion element 100, the arrangement pitch of incident light needs to be twice the pitch of the film of the polarization conversion element 100.

  Such a polarization conversion element 100 is generally used in combination with a fly-eye lens. FIG. 22 is a diagram showing an example of the configuration of a conventional liquid crystal projector apparatus. Light emitted from a light source lamp (such as a high-pressure mercury lamp) 111a of the light source unit 110 becomes a substantially parallel beam by the reflector 111b. This beam is split by the first fly-eye lens 112 and condensed at the position of the second fly-eye lens 113. This beam becomes a beam whose polarization is aligned by the polarization conversion element 100, and after passing through the first condenser lens 114, the reflection mirrors 115, 118, 120, 122, the dichroic mirrors 116, 117, the condensing lenses 119, 121, the second condenser. Irradiated onto the liquid crystal light valves 124R, 124G, and 124B of the respective colors via an optical system including lenses 123R, 123G, and 123B. In the example of FIG. 22, three systems of illumination light of red (R), green (G), and blue (B) are necessary. Therefore, dichroic mirrors 116 and 117 provide R, G at the rear stage of the first condenser lens 114. , B are separated into three systems.

  The polarization conversion element 100 is placed immediately after the second fly-eye lens 113 and plays a role of aligning the polarization direction as described above. In such an illumination system of a general liquid crystal projector device, the diameter of the beam incident on the polarization conversion element 100 is close to the position narrowed down by the first fly-eye lens 112, so that the second fly-eye lens 113 It is much smaller than the pitch. Accordingly, even if the polarization separation film 101 of the polarization conversion element 100 is configured in accordance with the pitch of the fly-eye lenses 112 and 113 and the reflection film 102 is formed between them, no light loss occurs.

On the other hand, considering that this polarization conversion element 100 is used in combination with an LED light source, the situation is different. Since the LED is a surface light source having an area, it cannot obtain parallel light and becomes diffused light. Therefore, it is difficult to focus with a fly-eye lens, and it is even difficult for the beam to maintain the size of the fly-eye lens.
Even if the beam width after the first fly-eye lens 112 shown in FIG. 22 can be maintained at the size of the second fly-eye lens 113, half of the polarization conversion element 100 must be shielded from light. In this case, it is meaningless to increase the amount of light by aligning the polarization in the polarization conversion element 100.

The present invention has been made in view of the above circumstances, and in order to eliminate the disadvantages of the prior art, the multi-wavelength compatible structure in which LEDs can be arranged at the same pitch as the arrangement pitch of the optical path separation unit of the polarization conversion element. An object is to provide a multi-wavelength polarization conversion element.
Another object of the present invention is to provide an illumination unit that uses the multi-wavelength polarization conversion element and has improved illumination efficiency.
A further object of the present invention is to provide an image display device that can obtain a bright display image by using the illumination unit with improved illumination efficiency.

In order to achieve the above object, the present invention adopts the following means.
A first means of the present invention is a multi-wavelength polarization conversion element that converts an aligned non-polarized beam into an aligned polarized beam having a uniform polarization direction and emits the converted non-polarized beam. The unpolarized beam is separated into a polarized beam having a first polarization direction (P-polarized light (or S-polarized light)) and a polarized beam having a second polarization direction (S-polarized light (or P-polarized light)) whose polarization directions are orthogonal to each other. An optical path separating unit having a function and a function of transmitting or reflecting the beam according to the wavelength of the non-polarized beam or the polarized beam, and “converting the polarization direction of the polarized beam (P-polarized light to S-polarized light, Or a polarization direction conversion unit having a function of converting S-polarized light into P-polarized light, and a non-polarized beam having a different wavelength is incident on an adjacent optical path separating unit in the arrayed optical path separating unit, and the optical path separating unit Above A structure in which emitted into a polarized beam of multiple wavelengths with aligned polarization through the light redirecting unit, the optical path separating portion is arranged to be inclined with respect to the incident optical axis, each other said free polarizing beam A polarization separation film that separates a polarized beam having a first polarization direction and a polarized beam having a second polarization direction that have orthogonal polarization directions, and transmits or reflects the beam according to the wavelength of the non-polarized beam or the polarized beam. The polarization separation film comprises an optical path separation film disposed in parallel with a dichroic film, and the polarization separation film converts the non-polarized beam into a transmitted light composed of a polarized beam having a first polarization direction (P-polarized light (or S-polarized light)) and a first light beam. The dichroic film is separated into reflected light composed of a polarized beam having two polarization directions (S-polarized light (or P-polarized light)), and the dichroic film is transmitted through the non-polarized light beam or the polarized light separating film incident on the optical path separating unit. With transmitting light direction of the polarized beam, characterized by reflecting a different second polarization direction of polarized beams of the wavelength reflected by the polarization splitting film of the optical path separating film adjacent.

According to a second means of the present invention, in the multi-wavelength polarization conversion element of the first means, the polarization direction conversion unit rotates the polarization plane of the polarized beam by 90 degrees to convert the polarization direction. The polarization direction conversion part is inclined and integrated with the optical path separation part.
According to a third means of the present invention, in the multi-wavelength polarization conversion element of the first or second means, the dichroic film is disposed at the last stage with respect to the incident direction of the non-polarized beam. It is characterized by.

A fourth means of the present invention is a multi-wavelength polarization conversion element of the first means, before Symbol polarization separation film is adjacent the optical path separating portion of the polarization separation film second polarization having the different wavelengths reflected by It is a polarization separation film for two wavelengths that reflects a polarized beam in the direction (S-polarized light (or P-polarized light)).

According to a fifth means of the present invention, in the multi-wavelength polarization conversion element according to the fourth means, the polarization direction converter is disposed in an optical path downstream of the polarization separation film, and the polarization plane of the polarized beam having a specific wavelength is changed. It has the function of a wavelength-selective wave plate that rotates 90 degrees to convert the polarization direction, and the polarization direction conversion unit is a polarization beam that has passed through the polarization separation film and a polarization separation film of an adjacent optical path separation unit. It acts as a half-wave plate only for one of the polarized beams having different wavelengths reflected and reflected again by the polarization separation film, and does not act as a half-wave plate for the other. Features.

A sixth means of the present invention is characterized in that, in the multi-wavelength polarization conversion element of any one of the first to fifth means, the number of optical paths of the non-polarized beam is varied depending on the wavelength. .
The seventh means of the present invention is the multi-wavelength polarization conversion element according to any one of the first to sixth means, wherein the non-polarized beam is a red region near a wavelength of 650 nm, a green region near a wavelength of 550 nm, It is characterized in that it is an unpolarized beam in the blue region near the wavelength of 450 nm, and the optical path corresponding to the unpolarized beam in the wavelength region in the green region is made larger than the optical paths of the wavelengths of other colors.
Further, an eighth means of the present invention is characterized in that, in the multi-wavelength polarization conversion element of the seventh means, one optical path corresponding to the non-polarized beam with the wavelength in the green region is arranged in one jump.

A ninth means of the present invention is an illumination unit, comprising the multi-wavelength polarization conversion element of any one of the first to eighth means, and a plurality of light sources having different wavelengths as light sources for emitting the arrayed non-polarized beams. The light emitting diode (LED) is provided.
According to a tenth means of the present invention, in the illumination unit of the ninth means, the light source is a non-polarized beam in a red region near a wavelength of 650 nm, a green region near a wavelength of 550 nm, and a blue region near a wavelength of 450 nm. It is a light emitting diode (LED) that emits light.

The eleventh means of the present invention comprises a coupling optical system for coupling a non-polarized beam emitted from the light emitting diode (LED) to the multi-wavelength polarization conversion element in the illumination unit of the ninth or tenth means. It is characterized by having.
According to a twelfth means of the present invention, in the illumination unit of the eleventh means, a tapered rod array with a convex surface is used as the coupling optical system.
Furthermore, the thirteenth means of the present invention is the illumination unit of any one of the ninth to twelfth means, comprising a condensing optical system for condensing the polarized light beams emitted from the multi-wavelength polarization conversion element. It is characterized by having.

14th means of this invention is an image display apparatus, It has the illumination unit of any one of 9th thru | or 13th means, and an image display element, It is characterized by the above-mentioned.
According to a fifteenth means of the present invention, in the image display device of the fourteenth means, the illumination unit is composed of one system.
The sixteenth means of the present invention is the image display device of the fourteenth or fifteenth means, further comprising a projection lens for projecting an image of the image display element.

In the multi-wavelength polarization conversion element of the present invention, “polarized light having a first polarization direction (P-polarized light (or S-polarized light)) that is arranged corresponding to the arranged non-polarized beams and whose polarization directions are orthogonal to each other. An optical path having a function of separating the beam into a polarized beam having a second polarization direction (S-polarized light (or P-polarized light)) and a function of transmitting or reflecting the beam according to the wavelength of the non-polarized beam or the polarized beam And a “polarization direction conversion unit having a function of converting the polarization direction of the polarized beam (converting P-polarized light to S-polarized light or S-polarized light to P-polarized light)”, and A non-polarized beam having a different wavelength is incident on an adjacent optical path separation unit, and is converted into a multi-wavelength polarized beam having the same polarization through the optical path separation unit and the polarization direction conversion unit, and is emitted. Conversion element A light source (for example, LED) can be arranged at the same pitch as the arrangement pitch of the optical path separation unit and the polarization direction conversion unit, and the amount of light can be increased as compared with a conventional polarization conversion element, thereby forming a bright illumination system. Is possible.
In addition, by configuring the optical path separation unit of the multi-wavelength polarization conversion element with a polarization separation film and a dichroic film, a multi-wavelength polarization conversion element can be realized using a common half-wave plate for the polarization direction conversion unit. it can.
Further, by using a wavelength-selective wave plate for the polarization direction conversion unit, the optical path separation unit can be configured with only a polarization separation film, and a multi-wavelength polarization conversion element with a simple configuration can be realized.

Further, when a plurality of wavelengths of LEDs are arranged and used as a light source for a non-polarized beam, the number of LED arrays is reduced by using the multi-wavelength polarization conversion element of the present invention as compared with the case of using a conventional type polarization conversion element. It is possible to construct a bright lighting unit.
Further, by using the illumination unit of the present invention in the illumination system of an image display device such as a projector device using an image display element such as a liquid crystal light valve, the number of LED arrays can be compared with that of a conventional illumination system using a polarization conversion element. Thus, an image display device such as a liquid crystal projector device that can display a bright image with a bright illumination unit can be realized.

  Furthermore, when a conventional polarization conversion element is used, it is necessary to combine illumination light from a plurality of illumination systems with a dichroic prism or the like in order to obtain a bright illumination system. By using the element, a single illumination system can be used, and a small and simple illumination unit and image display device can be configured.

  Hereinafter, the configuration, operation and action of the present invention will be described in detail based on the embodiments shown in the drawings.

[Example 1]
FIG. 1 is an explanatory diagram of a configuration of a multi-wavelength polarization conversion element showing an embodiment of the present invention.
FIG. 1A is a partial cross-sectional view showing a cross-sectional configuration example of a multi-wavelength polarization conversion element 10A, and between a transparent glass member 5, a polarization separation film 1 and a dichroic film 2 (2-1) as an optical path separation unit. , 2-2, 2-3) and an oblique incident corresponding type ½ wavelength film (or ½ wavelength plate) 3 which is a polarization direction conversion unit are overlapped to form an incident optical axis. Are arranged in a plurality of rows with an inclination of 45 °. Further, in this specification, a polarization separation film is used in order to perform polarization separation. This is because the ease of manufacturing is taken into consideration in relation to other structures. However, it goes without saying that it is possible to use a wire grid as a configuration for performing polarization separation. When this wire grid is used, the transmitted light can be P-polarized light, the reflected light can be S-polarized light, the transmitted light can be S-polarized light, and the reflected light can be P-polarized light.

In FIG. 1A, the number of pairs of the optical path separation film 4 and the half-wave film 3 is the same as the number of non-polarized beams from a light source (not shown) (for example, LED), and the polarization separation constituting the optical path separation film 4 The film 1 has a function of separating an unpolarized beam into transmitted light composed of a polarized beam having a first polarization direction (for example, P-polarized light) and reflected light composed of a polarized beam having a second polarization direction (for example, S-polarized light). ing. In addition, although this optical path separation film 4 described the case where the first polarization direction was P polarization and the second polarization direction was S polarization, the first polarization direction was S polarization, The polarization direction may be P-polarized light. In this case, in the following configuration, the correspondence may change depending on the handling of S-polarized light and P-polarized light, but it is understood that the correspondence can be read as appropriate.
The dichroic film 2 (2-1, 2-2, 2-3) has a wavelength selection function corresponding to two wavelengths, and the dichroic film 2-1 has a wavelength λ1 beam (non-polarized beam or polarized beam). ) And reflects the beam of wavelength λ3. The dichroic film 2-2 transmits a beam having a wavelength λ2 (non-polarized beam or polarized beam) and reflects a beam having a wavelength λ1. Further, the dichroic film 2-3 transmits a beam having a wavelength λ3 (non-polarized beam or polarized beam) and reflects a beam having a wavelength λ2.

The ½ wavelength film (obliquely incident type) 3 that is a polarization direction conversion unit has a function as a ½ wavelength plate that rotates the polarization plane of the polarized beam by 90 degrees to convert the polarization direction. That is, the P-polarized light transmitted through the half-wave film 3 is converted to S-polarized light, and the S-polarized light is converted to P-polarized light.
In FIG. 1A, the configuration corresponds to the three-wavelength non-polarized light beams having the wavelengths λ1 to λ3, but any number of different wavelengths can be used as long as there are a plurality of wavelengths. FIG. 1A shows a part of the multi-wavelength polarization conversion element 10A. The number of arrangements of the optical path separation film 4 and the half-wave film 3 is not limited to four. The number is set as appropriate.

  As shown in FIG. 1A, an optical path separation film 4 and a half-wavelength film 3 are overlapped, and a multi-wavelength polarization conversion element 10A having a configuration in which a plurality of rows are inclined at 45 ° with respect to the incident optical axis. As an example of the manufacturing method, as shown in FIG. 2, a polarizing plate 1, a dichroic film 2 and a half-wave film 3 are formed on a transparent parallel flat glass member 5. Further, a laminated structure is formed in which the necessary number of arrangements are stacked and bonded (adhering with a transparent adhesive or the like) in multiple stages. Next, as shown in FIG. 2, the laminated structure is cut along the broken lines A, B, C, and D, and the cut surfaces of the broken lines A and B are optically polished, as shown in FIG. The multi-wavelength polarization conversion element 10A having a structure can be easily manufactured.

In the multi-wavelength polarization conversion element 10A having the structure shown in FIG. 1A, the polarization separation film 1, the dichroic film 2, and the half-wave film 3 are arranged in this order when viewed from the incident side of the non-polarized beam. Not limited to this, the combinations of FIG. 3 to FIG. 8 are conceivable in the order of the arrangement of the polarization separation film 1, the dichroic film 2, and the half-wave film 3.
In this case, since there is almost no difference in performance as a polarization conversion element, it can be selected as appropriate depending on ease of design and ease of manufacture. If there is, the outgoing light becomes S-polarized light, and if the half-wave film 3 is provided in front of the polarization separation film 1, the outgoing light becomes P-polarized light.

  More specifically, FIG. 3 shows an embodiment in which the polarization separation film 1, the half wavelength film 3, and the dichroic film 2 are arranged in this order with respect to the incident beam. The optical path separation unit and the polarization direction conversion unit are integrated. It is arranged. In this arrangement example, the incident beam having the wavelength λ1 is separated into P-polarized light (transmitted light) and S-polarized light (reflected light) by the polarization separation film 1. The reflected light (S-polarized light) goes directly to the optical path separation unit (not shown) on the right. The transmitted light (P-polarized light) is converted to S-polarized light by the half-wave film 3 and passes through the dichroic film 2 as it is. Therefore, it is emitted as S-polarized light. On the other hand, reflected light having different wavelengths (S-polarized light having a wavelength λ3) from an optical path separation unit (not shown) adjacent to the left side of the figure is reflected by the dichroic film 2 and is emitted as S-polarized light.

  Next, FIG. 4 shows an embodiment in which the polarization separation film 1, the dichroic film 2, and the half-wave film 3 are arranged in this order with respect to the incident beam, and the polarization direction conversion unit is integrally disposed at the subsequent stage of the optical path separation unit. Has been. In this arrangement example, the incident beam having the wavelength λ1 is separated into P-polarized light (transmitted light) and S-polarized light (reflected light) by the polarization separation film 1. The reflected light (S-polarized light) goes directly to the optical path separation unit (not shown) on the right. The transmitted light (P-polarized light) passes through the dichroic film 2 as it is, and is converted into S-polarized light by the half-wave film 3. Therefore, it is emitted as S-polarized light. On the other hand, reflected light having different wavelengths (S-polarized light having a wavelength λ3) from an optical path separation unit (not shown) adjacent to the left side of the figure was once converted into P-polarized light by the half-wave film 3 and reflected by the dichroic film 2. Thereafter, the light is again converted into S-polarized light by the half-wave film 3 and emitted.

  Next, FIG. 5 shows an embodiment in which the dichroic film 2, the polarization separation film 1, and the half-wave film 3 are arranged in this order with respect to the incident beam, and the polarization direction conversion unit is integrally disposed after the optical path separation unit. Has been. In this arrangement example, an incident beam having a wavelength λ1 passes through the dichroic film 2 as it is, and is separated into P-polarized light (transmitted light) and S-polarized light (reflected light) by the polarization separation film 1. The reflected light (S-polarized light) again passes through the dichroic film 2 as it is, and travels to an optical path separation unit (not shown) on the right side. The transmitted light (P-polarized light) is converted into S-polarized light by the half-wave film 3. Therefore, it is emitted as S-polarized light. On the other hand, reflected light having different wavelengths (S-polarized light having a wavelength λ3) from an optical path separation unit (not shown) adjacent to the left side of the figure is converted into P-polarized light by the half-wavelength film 3 and transmitted through the polarization separation film 1 to be dichroic. After being reflected by the film 2, it is again transmitted through the polarization separation film 1, converted to S-polarized light again by the ½ wavelength film, and emitted.

  Next, FIG. 6 shows an embodiment in which the dichroic film 2, the half-wave film 3, and the polarization separation film 1 are arranged in this order with respect to the incident beam. The optical path separation unit and the polarization direction conversion unit are integrally disposed. Yes. In this arrangement example, the incident beam having the wavelength λ1 is transmitted through the dichroic film 2 as it is, and is still randomly polarized even though it is transmitted through the ½ wavelength film 3, and the polarization separation film 1 causes P-polarized light (transmitted light) and S Separated into polarized light (reflected light). The transmitted light (P-polarized light) is emitted as P-polarized light as it is. The reflected light (S-polarized light) is again transmitted through the half-wave film 3 to be converted into P-polarized light, passes through the dichroic film 2 as it is, and travels to an optical path separation unit (not shown) on the right side. On the other hand, reflected light having different wavelengths (P-polarized light having a wavelength λ3) from an optical path separating unit (not shown) adjacent to the left side of the figure passes through the polarization separation film 1 and is converted into S-polarized light by the half-wavelength film 3 once. After being reflected by the dichroic film 2, it is converted again to P-polarized light by the half-wave film 3, passes through the polarization separation film 1, and is emitted as P-polarized light.

  Next, FIG. 7 shows an embodiment in which the half-wave film 3, the dichroic film 2, and the polarization separation film 1 are arranged in this order with respect to the incident beam. Has been. In this arrangement example, the incident beam having the wavelength λ1 is still randomly polarized even if it passes through the half-wavelength film 3, passes through the dichroic film 2 as it is, and the polarization separation film 1 transmits P-polarized light (transmitted light) and S Separated into polarized light (reflected light). The transmitted light (P-polarized light) is emitted as P-polarized light as it is. The reflected light (S-polarized light) is again transmitted through the dichroic film 2 as it is, converted to P-polarized light by the half-wave film 3 and directed to the optical path separation unit (not shown) on the right side. On the other hand, reflected light having different wavelengths (P-polarized light having a wavelength λ3) from an optical path separation unit (not shown) adjacent to the left side of the figure is transmitted through the polarization separation film 1, reflected by the dichroic film 2, and then again the polarization separation film 1. Is transmitted as P-polarized light.

  Next, FIG. 8 shows an embodiment in which the half-wave film 3, the polarization separation film 1, and the dichroic film 2 are arranged in this order with respect to the incident beam. Has been. In this arrangement example, the incident beam having the wavelength λ1 is still randomly polarized even after passing through the half-wavelength film 3, and is separated into P-polarized light (transmitted light) and S-polarized light (reflected light) by the polarization separation film 1. The The transmitted light (P-polarized light) passes through the dichroic film 2 as it is and is emitted as P-polarized light. The reflected light (S-polarized light) is again transmitted through the half-wave film 3 and converted to P-polarized light, and travels to the optical path separation unit (not shown) on the right. On the other hand, reflected light having different wavelengths (P-polarized light having a wavelength λ3) from an optical path separation unit (not shown) adjacent to the left side of the figure is reflected by the dichroic film 2 and emitted as P-polarized light.

  The above six examples are arranged in terms of the wavelengths that the polarization separation film 1, the dichroic film 2, and the half-wave film 3 should correspond to, as shown in Table 1 below, and the dichroic film 2 is arranged at the last stage. The configuration shown in FIG. 3 or FIG. 8 is the simplest configuration in terms of design. That is, in the configuration of FIG. 3 or FIG. 8, reflected light (S-polarized light or P-polarized light of wavelength λ3) having different wavelengths from an optical path separation unit (not shown) adjacent to the left side of the figure is reflected by the dichroic film 2 and emitted as it is. Therefore, the polarization separation film 1 and the half-wave film 3 may be one wavelength compatible, and the design is simplified. However, a combination of films different by the number of wavelengths of the incident beam is required (when there are three wavelengths λ1 to λ3 as shown in FIG. 1, the number of film combinations is × 3 as shown in Table 1). . Note that the polarization separation film 1 and the half-wave film 3 other than the dichroic film 2 are simplified in manufacture if they are designed to cover all wavelengths.

  The multi-wavelength polarization conversion element 10A in FIG. 1A is an example of a film configuration corresponding to FIG. 4, but if this is used upside down, the film configuration as shown in FIG. The multi-wavelength polarization conversion element 10B of the example of the film configuration), and the same multi-wavelength polarization conversion element is inverted upside down with respect to the incident beam having the same wavelength arrangement and shifted by one pitch horizontally, thereby polarizing the emitted light. Either P-polarized light or S-polarized light can be adopted.

In the multi-wavelength polarization conversion element 10A (or 10B) of the present embodiment configured as described above, a non-polarized beam light source (for example, LED) is disposed at the same pitch as the arrangement pitch of the optical path separation unit and the polarization direction conversion unit. Therefore, the amount of light can be increased almost twice as compared with the conventional polarization conversion element, and a bright illumination system as described later can be configured.
In addition, by configuring the optical path separation unit of the multi-wavelength polarization conversion element with a polarization separation film and a dichroic film, a multi-wavelength polarization conversion element can be realized using a common half-wave plate for the polarization direction conversion unit. it can.

[Example 2]
FIG. 9 is a diagram for explaining the configuration of a multi-wavelength polarization conversion element according to the second embodiment of the present invention.
FIG. 9A includes an optical path separation film 4 serving as an optical path separation unit and a wave plate 6 serving as a polarization direction conversion unit for incident light of each non-polarized beam having wavelengths λ1 to λ3. In the embodiment, the optical path separation film 4 separates the non-polarized beam into transmitted light composed of a polarized beam having a first polarization direction (P-polarized light) and reflected light composed of a polarized beam having a second polarization direction (S-polarized light). The polarization separation film 1 includes a polarization separation film 1 and is a two-wavelength polarization separation film that reflects reflected light having different wavelengths reflected by the polarization separation film of the adjacent optical path separation unit. The wavelength plate 6 is a wavelength-selective wavelength plate that functions as a λ plate or a half-wave plate depending on the wavelength.

  That is, in the multi-wavelength polarization conversion element 10C having the configuration shown in FIG. 9A, the incident beam is separated into P-polarized light (transmitted light) and S-polarized light (reflected light) by the polarization separation film 1, and transmitted light (P-polarized light). Straightly enters the wave plate 6 with P-polarized light, and the reflected light (S-polarized light) from the adjacent polarization separation film 1 of the adjacent beams having different wavelengths is reflected by the polarization separation film 1 and is the same with the S-polarization. Is incident on the wave plate 6. The wave plate 6 acts as a half wave plate only for one of the beams incident on the same wave plate, and does not act as a wave plate for the other (as one wave plate (λ plate)). The wavelength plate is a wavelength-selective wave plate, so that both wavelengths are aligned with P-polarized light or S-polarized light, and emitted as a multi-wavelength polarized beam with the same polarization direction. An example of such a wavelength-selective wave plate 6 can be found in, for example, Japanese Patent Application Laid-Open No. 2000-510961.

  Next, the polarization conversion element 10D shown in FIG. 9B is an example in which the optical path separation film 4 includes the polarization separation film 1 and the dichroic films 2-1 to 2-3 as in the first embodiment. Since the function is not changed from 9 (a) and only a dichroic film is added, it is wasteful and not preferable to take such a configuration.

  Further, the polarization conversion element 10E shown in FIG. 9C is an example in which the wave plate 6 is disposed obliquely along the polarization separation film 1, and such a configuration is possible, but in this case, the adjacent light is polarized. In order to reflect the light again by the separation film 1, it is necessary that the adjacent light does not act as a half-wave plate. That is, when the incident beam is separated into P-polarized light (transmitted light) and S-polarized light (reflected light) by the polarization separation film 1, the adjacent light of different wavelengths is reflected by the polarization separation film 1 as S-polarized light. In order for light to be reflected by the polarization separation film 1 while being S-polarized light, the wave plate 6 needs not to act as a half-wave plate for the beam. Accordingly, in such a configuration, since the outgoing light is limited to only S-polarized light, it is necessary to add a half-wave plate in order to obtain P-polarized light, which is not preferable.

  As described above, in this embodiment, by using the wavelength selective wave plate for the polarization direction converter, the multi-wavelength polarization conversion element 10C having the configuration as shown in FIG. A multi-wavelength polarization conversion element that can be configured by only the polarization separation film 1 and can emit with a simple configuration with the polarization directions of the beams having a plurality of wavelengths aligned is realized.

[Example 3]
Next, an example of an illumination unit using the multi-wavelength polarization change element of the present invention is shown.
FIG. 10 shows an example in which the multi-wavelength polarization conversion element 10 shown in the first embodiment or the second embodiment is used in an illumination unit applied to an illumination system of an image display device such as a projector device.
This illumination unit uses LED chips 11R, 11G, and 11B having a plurality of wavelengths as light sources, and the LED chips 11R, 11G, and 11B are arranged at equal intervals, and adjacent LED chips have wavelengths (colors) of emitted light. And a tapered rod array 12 in which the emitted light is arrayed with a tapered rod (which suppresses the spread of the beam while integrating) with a convex surface (for example, a convex surface having a radius of curvature R) as an example of a coupling optical system. Thus, the light is guided to the multi-wavelength polarization conversion element 10 of the present invention, and a condensing optical system including the fly-eye lens 13 and the condenser lenses 14 and 15 is disposed at the subsequent stage of the multi-wavelength polarization conversion element 10.

  Here, the LED chip 11R emits a non-polarized beam in the red region near the wavelength of 650 nm, the LED chip 11G emits a non-polarized beam in the green region near the wavelength of 550 nm, and the LED chip 11B emits a blue region near the wavelength of 450 nm. A non-polarized beam is emitted. Then, the non-polarized beams emitted from the LED chips 11R, 11G, and 11B are guided to the multi-wavelength polarization conversion element 10 by the tapered rod array 12 with R, and are polarized beams whose polarization directions are aligned by the multi-wavelength polarization conversion element 10. Emitted. The polarized beam emitted from the multi-wavelength polarization conversion element 10 is condensed by the fly-eye lens 13 and the condenser lenses 14 and 15 to illuminate the image display element (for example, a liquid crystal light valve) 16 as white light. Of course, in an image display device such as a projector device, a projection lens, which is a projection means, is disposed in the subsequent stage, and an image created by the liquid crystal light valve 16 is projected onto a screen or the like by the projection lens. An embodiment of the image display device will be described later.

Here, FIG. 11 shows an illumination unit using the conventional polarization conversion element (configuration of FIG. 21) presented for comparison. In the conventional polarization conversion element 100, as shown in FIG. And the reflective film, the LED chips 11R, 11G, and 11B can be arranged in a single array with respect to the film arrangement of the polarization conversion element 100.
On the other hand, in the illumination unit of the present invention, by using the multi-wavelength polarization conversion element 10 shown in the first embodiment or the second embodiment, the LED chips 11R and 11G with respect to the film arrangement of the multi-wavelength polarization conversion element 10 are used. , 11B can be arranged in a one-to-one array, and the number of LED arrays can be nearly doubled, so that a bright projector apparatus having a larger amount of light than before can be constructed even if an LED with insufficient amount of light is used as a light source.

  In addition, when the conventional polarization conversion element having the configuration shown in FIG. 21 is used, the amount of LEDs cannot be obtained because the number of LEDs is small, and the amount of light is insufficient for colorization (particularly, the amount of light in the green region is insufficient). In order to compensate for this, two illumination systems were provided as shown in FIG. 12, and optical path synthesis by the dichroic prism 21 was necessary. However, by using the multi-wavelength polarization conversion element 10 of the present invention, as shown in FIG. Thus, the number of LEDs can be increased, and the amount of light can be sufficiently increased even with a single illumination system.

  FIG. 10 shows an example in which the multi-wavelength polarization conversion element 10 of the present invention and the R-attached tapered rod array 12 are combined. As shown in FIG. 13, the coupling optical system includes lenses other than the tapered rod array. An array (such as a fly-eye lens) 22 may be used. In this case as well, the multi-wavelength polarization conversion element 10 of the present invention works effectively. However, considering the light utilization efficiency of the light emitted from the light source, the use of the tapered tape array 12 with R has the following advantages.

FIG. 14 is a diagram illustrating a shape of a rectangular parallelepiped rod, a tapered rod, a tapered rod having an R surface, and a light condensing state.
FIG.14 (c) is a figure which shows the taper rod with a convex surface which concerns on the Example of FIG. Here, as an example of the convex shape, an R surface (a convex surface having a radius of curvature R) is used. As shown in FIGS. 14A and 14B, the light beam can be made parallel to the optical axis by using a tapered rod rather than a rectangular parallelepiped rod. By transmitting the convex surface (R surface) of the tapered rod with a convex surface as shown in FIG. 14C, it becomes possible to bring the light beam (light beam) of the outer peripheral portion to the center, and obtain a light beam more parallel to the optical axis. be able to.

  FIG. 15 is a diagram showing a light source unit using a tapered rod 12 having an R surface on the exit surface in a coupling optical system. Looking at the coupling efficiency at the tapered rod incident end, the light beam emitted from the solid light source 11 such as an LED is refracted at the incident end of the tapered rod 12 and is incident on the rod. Therefore, if the light emitting surface of the solid light source 11 and the rod incident end are brought into close contact with each other, the coupling efficiency can be made 100%. Actually, even if a slight gap is provided due to heat generation or the like, it is possible to provide a considerably high coupling efficiency.

Next, the propagation of the light beam in the taper rod 12 will be considered. For example, when the glass material of the taper rod 12 is BK7 (refractive index of about 1.52), the critical angle is about 41.14 °, so the angle formed between the light beam entering the taper rod 12 from the incident end and the optical axis is 41.14 ° or less. Therefore, since these light beams are totally reflected by the side surface (taper surface) of the taper rod 12, there is almost no loss of light quantity related to the propagation of the beam in the rod.
If the angle of the taper surface is α, the angle of the light beam approaches the optical axis by 2α every time it is reflected once. If the taper rod 12 is infinitely long, all the light beams reach the exit end below the rod angle.

  However, there is a limitation on the size of the emission end, and there is a limit in itself even if it is made longer. If the size of the entrance end and the exit end is fixed, the shorter the rod, the greater the taper angle, and the smaller the angle of the beam with a single reflection, the less the number of reflections. On the other hand, if the rod is lengthened, the number of reflections increases, but the beam angle decrease in one reflection becomes small. In any case, there is a beam having an angle larger than the angle of the rod at the exit end. Of these, the one with the maximum angle will be referred to as the maximum angle beam in the rod.

  Next, let us look at the behavior of the light beam on the exit surface. If the exit surface is a plane perpendicular to the optical axis, a light beam having an angle with respect to the optical axis is refracted at the exit surface and diverges as a light beam having a larger angle. In order to suppress this as much as possible, a convex surface (R surface) having a radius of curvature R is attached to the emission end face. In FIG. 15, this R plane is formed as a radius of curvature R so that the maximum angle beam in the rod at the upper and lower ends of the exit end face is parallel to the optical axis after exiting the rod. Therefore, at this time, the light beam parallel region after the emission can be made the longest. The length of the parallel region is effective for the light use efficiency of the illumination system of the projector device.

  In the present embodiment, the end shape of the tapered rod with a convex surface is not limited to the R surface, and the same effect can be obtained by arranging, for example, a trapezoidal surface or a large number of planes along the surface. A similar effect can be obtained by using a hollow taper rod in which four mirrors having an inclination with respect to the optical axis are combined in a quadrangular pyramid instead of the transparent taper rod. However, in the case of a hollow taper rod, since there is no exit end face, it is necessary to form a convex surface such as an R surface or a trapezoidal surface as a separate member at the exit portion.

[Example 4]
In an image display device such as a projector device using an LED as a light source, it is necessary to set the light quantity ratio to green (G) >> red (R)> blue (B) in order to achieve white balance. On the other hand, the amount of light emitted from the LED is G≈R> B, and an ideal white color can be obtained by setting the number of LEDs (number of optical paths) to G> R≈B or G>R> B. Therefore, if the number of effective optical paths of the multi-wavelength polarization conversion element is matched with this, the configuration of the optical system becomes easy.

  Therefore, as shown in FIG. 16, the wavelength of the non-polarized beam incident on the multi-wavelength polarization conversion element is set to a red region near a wavelength of 650 nm, a green region near a wavelength of 550 nm, and a blue region near a wavelength of 450 nm. (G) It is preferable to arrange one corresponding optical path in the region.

  FIG. 17 shows an example of an illumination unit having a configuration in which one optical path corresponding to the green (G) region of the multi-wavelength polarization conversion element 10 is arranged in a jump. The green (G) LED chip 11G is replaced with another color LED. More than the chips 11R and 11B, one is arranged in a jump. Accordingly, the image display element (liquid crystal light valve or the like) 16 can be illuminated with white light that is close to ideal.

[Example 5]
Next, an embodiment of the image display device is shown.
FIG. 18 is a diagram showing a configuration example of an image display device using the illumination unit of the present invention, and this image display device is an example of a three-plate transmissive liquid crystal projector device.
The illumination unit 20 is, for example, an illumination unit having a configuration substantially similar to the configuration of FIG. 10 described in the third embodiment. From the multi-wavelength polarization conversion element 10 of the illumination unit 20, a multi-wavelength polarized beam having a uniform polarization direction is provided. Is emitted. The multi-wavelength polarized beam is condensed by the fly-eye lens 13 and the first condenser lens 14, reflected by the reflecting mirror 25 and incident on the dichroic mirror 26. The dichroic mirror 26 acts to transmit red light (R light) and reflect green light (G light) and blue light (B light). The R light transmitted through the dichroic mirror 26 is reflected by a reflection mirror 28. The reflected light illuminates the transmissive liquid crystal light valve 34R for red via the second condenser lens 33R. On the other hand, the G light and the B light reflected by the dichroic mirror 26 enter the second dichroic mirror 27, the G light is reflected by the dichroic mirror 27, and the B light passes through the dichroic mirror 27. The G light reflected by the dichroic mirror 27 illuminates the green transmissive liquid crystal light valve 34G through the second condenser lens 33G. Further, the B light transmitted through the dichroic mirror 27 illuminates the blue transmissive liquid crystal light valve 34B through the lenses 29 and 31, the reflecting mirrors 30 and 32, and the second condenser lens 33B. Display images of the transmissive liquid crystal light valves 34R, 34G, and 34B illuminated by the R, G, and B color illumination lights are synthesized by the dichroic prism 35 and projected onto a screen or the like (not shown) by the projection lens 36 to display an image. Is done.

In the three-plate transmissive liquid crystal projector apparatus of the present embodiment, since the multi-wavelength polarization conversion element 10 of the above-described embodiment is used for the illumination unit, the number of LED chip arrays can be increased nearly double compared to the conventional case. In addition, since the number of green lights is larger than that of other colors, a bright display image with good white balance can be obtained.
Further, the rear projection type projection TV can be provided by installing the liquid crystal projector apparatus having the configuration shown in FIG. 18 in a light-shielded casing and projecting from the back onto a screen installed on the front of the casing. .

[Example 6]
FIG. 19 is a diagram showing another configuration example of an image display device using the illumination unit of the present invention, and this image display device is an example of a single-plate transmissive liquid crystal projector device.
The illumination unit 40 is, for example, an illumination unit having the same configuration as that of FIG. 10 described in the third embodiment. A multi-wavelength polarized beam having a uniform polarization direction is emitted from the multi-wavelength polarization conversion element 10 of the illumination unit 40. The The multi-wavelength polarized beam is condensed by the fly-eye lens 13, the first condenser lens 14, and the second condenser lens 15 to illuminate the transmissive liquid crystal light valve 41. The display image of the transmissive liquid crystal light valve 41 illuminated with the illumination light combining R, G, and B is projected onto a screen or the like (not shown) by the projection lens 42, and image display is performed.

  In this single-plate transmissive liquid crystal projector device, the R, G, B image display by the transmissive liquid crystal light valve 15 is time sequential (time-division display (display switching for each time)), so the amount of light for each color is small. However, the configuration of the optical system is extremely simple compared to the three-plate type.

[Example 7]
FIG. 20 is a diagram showing still another configuration example of an image display apparatus using the illumination unit of the present invention, and this image display apparatus is an example of a single-plate reflection type liquid crystal projector apparatus.
The illumination unit 50 is, for example, an illumination unit having substantially the same configuration as that of FIG. 10 described in the third embodiment. From the multi-wavelength polarization conversion element 10 of the illumination unit 50, a multi-wavelength polarized beam having a uniform polarization direction is used. Is emitted. The multi-wavelength polarized beam is condensed by the fly-eye lens 13, the first condenser lens 14, and the second condenser lens 15, passes through the polarization beam splitter (PBS) 17, and is a reflective liquid crystal light valve (LCOS) 51. Illuminate. The display image of the reflective liquid crystal light valve (LCOS) 51 illuminated with the illumination light composed of R, G, and B is reflected by the polarization beam splitter (PBS) 17 and projected onto a screen or the like (not shown) by the projection lens 52. Image display is performed.

Also in this single-plate reflection type liquid crystal projector device, the R, G, B image display by the reflection type liquid crystal light valve (LCOS) 51 is time sequential (time-division display (display switching for each time)). Although the amount of light is reduced, the configuration of the optical system is extremely simple compared to the three-plate type.
In the single-plate reflection type liquid crystal projector apparatus having the configuration shown in FIG. 20, the optical path is deflected by 90 ° by the polarization beam splitter (PBS) 17, so the single-plate reflection type liquid crystal projector apparatus is installed in a light-shielded casing. A thin rear projection type projection TV can be easily realized by projecting from the back onto a screen installed on the front surface of the housing.

1 is a configuration explanatory diagram of a multi-wavelength polarization conversion element showing an embodiment of the present invention. FIG. It is explanatory drawing of the preparation methods of the multiwavelength polarization conversion element shown to Fig.1 (a). It is a figure which shows an example of arrangement | positioning order of a polarization separation film, a dichroic film, and a 1/2 wavelength film which comprise the multiwavelength polarization conversion element based on this invention, and optical path separation and polarization conversion. It is a figure which shows another example of arrangement | positioning order of the polarization separation film, dichroic film, and 1/2 wavelength film which comprise the multiwavelength polarization conversion element which concerns on this invention, and optical path separation and polarization conversion. It is a figure which shows another example of arrangement | positioning order of the polarization separation film, dichroic film, and 1/2 wavelength film which comprise the multiwavelength polarization conversion element which concerns on this invention, and optical path separation and polarization conversion. It is a figure which shows another example of arrangement | positioning order of the polarization separation film, dichroic film, and 1/2 wavelength film which comprise the multiwavelength polarization conversion element which concerns on this invention, and optical path separation and polarization conversion. It is a figure which shows another example of arrangement | positioning order of the polarization separation film, dichroic film, and 1/2 wavelength film which comprise the multiwavelength polarization conversion element which concerns on this invention, and optical path separation and polarization conversion. It is a figure which shows another example of arrangement | positioning order of the polarization separation film, dichroic film, and 1/2 wavelength film which comprise the multiwavelength polarization conversion element which concerns on this invention, and optical path separation and polarization conversion. It is a structure explanatory drawing of the multiwavelength polarization conversion element which shows another Example of this invention. It is a figure which shows the structural example of the illumination unit using the multiwavelength polarization conversion element of this invention. It is a figure which shows the structural example of the illumination unit using the conventional polarization conversion element. It is a figure which shows the structural example of the illumination unit which increased the light quantity using two illumination systems using the conventional polarization conversion element. It is a figure which shows another structural example of the illumination unit using the multiwavelength polarization conversion element of this invention. It is a figure which shows the shape of a rectangular parallelepiped rod, a taper rod, and the taper rod which has R surface, and the condensing state of light. It is explanatory drawing of the illumination system using the taper rod with R surface. It is a figure which shows the structural example of the multiwavelength polarization conversion element which increased the optical path of green light. It is a figure which shows the structural example of the illumination unit which increased the optical path of green light. 1 is a schematic configuration diagram of a three-plate transmission type liquid crystal projector device showing a configuration example of an image display device using an illumination unit of the present invention. It is a schematic block diagram of the single-plate-type transmissive | pervious liquid crystal projector device which shows another structural example of the image display apparatus using the illumination unit of this invention. It is a schematic block diagram of the single-plate reflection type liquid crystal projector device which shows another structural example of the image display apparatus using the illumination unit of this invention. It is a figure which shows the structural example of the conventional polarization conversion element. It is a schematic block diagram of the 3 plate type | mold transmission-type liquid crystal projector device which shows the structural example of the image display apparatus which used the conventional polarization conversion element for the illumination system.

Explanation of symbols

1: Polarization separation film 2 (2-1, 2-2, 2-3): Dichroic film 3: 1/2 wavelength film (or 1/2 wavelength plate)
4: Optical path separation film (optical path separation part)
5: Glass member 6: Wavelength selective wave plate 10, 10A, 10B, 10C, 10D, 10E: Multi-wavelength polarization conversion element 11R: Light-emitting diode (LED) in the red region
11G: Light emitting diode (LED) in the green range
11B: Light emitting diode (LED) in the blue region
12: Tapered rod with convex surface (or tapered rod array)
13: Fly-eye lens 14: First condenser lens 15: Second condenser lens 16: Liquid crystal light valve (image display element)
17: Polarized beam splitter (PBS)
20, 40, 50: Illumination unit 22: Fly eye lens 25, 28, 30, 32: Reflection mirror 26, 27: Dichroic mirror 29, 31: Lens 33R, 33G, 33B: Second condenser lens 34R: Red liquid crystal light Valve (image display element)
34G: Green liquid crystal light valve (image display element)
34B: Blue liquid crystal light valve (image display element)
35: Dichroic prism 36, 42, 52: Projection lens 41: Transmission type liquid crystal light valve (image display element)
51: Reflective liquid crystal light valve (LCOS)

Claims (16)

In the multi-wavelength polarization conversion element that converts the aligned non-polarized beam into an aligned polarized beam with a uniform polarization direction and emits it,
A function of separating the non-polarized beam into a polarized beam having a first polarization direction and a polarized beam having a second polarization direction which are arranged corresponding to the arranged non-polarized beams and whose polarization directions are orthogonal to each other; Or an optical path separating unit having a function of transmitting or reflecting the polarized beam according to the wavelength of the polarized beam;
A polarization direction converter having a function of converting the polarization direction of the polarized beam;
Non-polarized beams having different wavelengths are incident on the adjacent optical path separation units in the arrayed optical path separation units, and are converted into polarized light beams with uniform polarization through the optical path separation unit and the polarization direction conversion unit. It is a configuration to emit,
The optical path separating unit is arranged to be inclined with respect to the incident optical axis, and separates the non-polarized beam into a polarized beam having a first polarization direction and a polarized beam having a second polarization direction whose polarization directions are orthogonal to each other. An optical path separation film in which a separation film and a dichroic film that transmits or reflects the non-polarized beam or the polarized beam according to the wavelength of the polarization beam are arranged in parallel;
The polarization separation film separates the non-polarized beam into transmitted light composed of a polarized beam in a first polarization direction and reflected light composed of a polarized beam in a second polarization direction, and the dichroic film is incident on the optical path separation unit. A non-polarized light beam or a polarized light beam having a first polarization direction that has passed through the polarization separation film, and a second polarization direction having a different wavelength reflected by the polarization separation film of the adjacent optical path separation film. A multi-wavelength polarization conversion element that reflects a polarized beam . The multi-wavelength polarization conversion element according to claim 1,
The polarization direction conversion unit has a function of a half-wave plate that changes the polarization direction by rotating the polarization plane of the polarized beam by 90 degrees, and tilts the polarization direction conversion unit along the optical path separation unit. And a multi-wavelength polarization conversion element characterized by being integrally arranged . The multi-wavelength polarization conversion element according to claim 1 or 2,
The multi-wavelength polarization conversion element , wherein the dichroic film is disposed at the last stage with respect to an incident direction of the non-polarized beam . The multi-wavelength polarization conversion element according to claim 1 ,
The polarization separation film is a two-wavelength polarization separation film that reflects a polarized beam of the second polarization direction having a different wavelength reflected by the polarization separation film of the adjacent optical path separation unit. Wavelength polarization conversion element. The multi-wavelength polarization conversion element according to claim 4 ,
The polarization direction conversion unit is disposed in the optical path downstream of the polarization separation film, and has a function of a wavelength-selective wave plate that rotates the polarization plane of a polarized beam having a specific wavelength by 90 degrees to change the polarization direction. The polarization direction conversion unit is either a polarized beam transmitted through the polarization separation film or a polarized beam having a different wavelength reflected by the polarization separation film of the adjacent optical path separation unit and reflected again by the polarization separation film. A multi-wavelength polarization conversion element that acts as a half-wave plate only on the other side and does not act as a half-wave plate on the other side . In the multiwavelength polarization conversion element according to any one of claims 1 to 5 ,
The multi-wavelength polarization conversion element, wherein the number of optical paths of the non-polarized beam is varied according to the wavelength. In the multiwavelength polarization conversion element according to any one of claims 1 to 6,
The non-polarized beam is a non-polarized beam in a red region near a wavelength of 650 nm, a green region near a wavelength of 550 nm, and a blue region near a wavelength of 450 nm, and an optical path corresponding to the non-polarized beam having a wavelength in the green region is different. A multi-wavelength polarization conversion element characterized in that the number of optical paths is larger than the optical path of the wavelength of the color . The multi-wavelength polarization conversion element according to claim 7 ,
A multi-wavelength polarization conversion element characterized in that one optical path corresponding to a non-polarized beam having a wavelength in the green region is arranged in a jump . A multi-wavelength polarization conversion element according to any one of claims 1 to 8 , comprising a plurality of light emitting diodes (LEDs) having different wavelengths as a light source for emitting the arrayed non-polarized beam. Lighting unit . The lighting unit according to claim 9 ,
The light source is a light emitting diode (LED) that emits a non-polarized beam in a red region near a wavelength of 650 nm, a green region near a wavelength of 550 nm, and a blue region near a wavelength of 450 nm . The lighting unit according to claim 9 or 10,
An illumination unit comprising a coupling optical system for coupling a non-polarized beam emitted from the light emitting diode (LED) to the multi-wavelength polarization conversion element . The lighting unit according to claim 11 .
An illumination unit using a tapered rod array with a convex surface as the coupling optical system . The lighting unit according to any one of claims 9 to 12 ,
An illumination unit comprising a condensing optical system that condenses a beam with uniform polarization emitted from the multi-wavelength polarization conversion element . An illumination unit according to any one of claims 9 to 13, an image display device characterized by having an image display device. The image display device according to claim 14 ,
An image display device characterized in that the illumination unit is composed of one system . The image display device according to claim 14 or 15,
An image display apparatus comprising a projection lens that projects an image of the image display element .

Images