JP5515200B2 - Illumination optical system and projector apparatus - Google Patents

Description

  The present invention relates to an illumination optical system and a projector apparatus.

  In recent years, the brightness of light-emitting diodes (abbreviated as LEDs) has been improved, attracting attention as various illumination light sources, and has been studied as a light source for projector apparatuses. Advantages of using an LED as the light source of the projector device include a long life as a light source and ease of color balance. However, when an LED is viewed as a light source of a projector device for a large screen, a shortage of light amount is a big problem, and an illumination optical system with high light utilization efficiency is required. When a liquid crystal panel is used as a light valve of a projector device, an illumination optical system including efficient polarization conversion is particularly important.

  Various studies have been made on individual parts of the illumination optical system, and many technical proposals have been made, but it cannot be said that sufficient studies have been made when viewed as a total illumination optical system including polarization conversion.

  As an example of combination as an illumination optical system, for example, Patent Document 1 discloses an example in which an LED including a photonic crystal and a polarization conversion element are combined (FIG. 11 of Patent Document 1).

  Patent Document 2 discloses an illumination optical system (FIGS. 7 and 8 of Patent Document 2) in which a fly-eye lens, a polarization conversion element, and a rod integrator are combined. In a liquid crystal projector using a conventional lamp light source, an illumination optical system using a fly-eye lens is common. FIG. 16 shows a configuration example of the fly-eye lens system. In this illumination optical system, a light beam from a light source such as a lamp is reflected by a parabolic mirror and becomes a beam substantially parallel to the optical axis to reach the fly-eye lens, as shown in FIG. The light beam is imaged on the second fly-eye lens by the first fly-eye lens, and can pass through the fly-eye lens without loss of light quantity.

In Patent Document 3, a wire grid reflection type deflection / separation element configured to transmit P-polarized light and reflect S-polarized light is disposed at the output end of the taper rod, and the S-polarized component is returned into the taper rod and repeatedly reflected. Discloses an illumination optical system in which a light beam changed to P-polarized light is extracted as transmitted light and all light components are used.
JP 2006-39277 A JP 2005-309144 A Japanese Patent Laid-Open No. 2005-23440

  As described above, a technique for improving the light utilization efficiency of an illumination optical system including a light valve such as a liquid crystal panel has been disclosed, but light from a relatively weak light source such as an LED is used as a projector device for a large screen. It was not enough to use. For example, the combination of the LED and the photonic crystal disclosed in Patent Document 1 cannot be said to sufficiently converge the light beam, and the light utilization efficiency cannot be sufficiently improved. As shown in FIG. 15, the light emission distribution of the LED provided with the photonic crystal is as shown by the broken line in FIG. In the region close to 0 °, the improvement is about 1.5 times. However, as a whole, the light beam spreads to 90 °, and when considering an effective capture angle of 10 ° to 15 ° in the case of a liquid crystal panel, the ratio of effective light to the total amount of emitted light is only about 30%. .

  When the illumination optical system disclosed in Patent Document 2 is applied to an LED light source, the configuration is as shown in FIGS. 16B and 16C, but problems occur in two respects. One is that, as shown in FIG. 16 (b), of the light emitted from the LEDs, the number of beams that can be effectively captured is small. Another problem is that the LED is a surface light source. As shown in FIG. 16C, the beam from the end of the surface light source is blocked by the aperture of the polarization conversion element. is there. For these reasons, there is a limit to increasing the light utilization efficiency in the combination of the LED and the fly-eye lens.

  The illumination optical system disclosed in Patent Document 3 can theoretically obtain P-polarized light with high efficiency, but the efficiency does not increase in consideration of the light transmission efficiency and reflection efficiency of the tapered rod. A prototype with a similar structure, in which a λ / 4 plate is incorporated to improve efficiency, has been announced by 3M. Since this is an isolator system, the efficiency should be good, but the light returned to the LED direction must be reflected again to the exit surface side of the taper rod, and the efficiency there is not high, so overall, In contrast to the case where the polarization separation element is not inserted, the efficiency increase when the polarization separation element is inserted is only about 1.2 times.

  In the present invention, based on such a current situation, illumination optics with high light utilization efficiency that can obtain sufficiently bright projection light even with a light source having a relatively small amount of light such as an LED in a projector device provided with a light valve. It is an object of the present invention to provide a system and a projector apparatus including the illumination optical system.

  In order to solve the above problems, the present inventors have found that an illumination optical system with high light utilization efficiency is configured by combining a polarization conversion element having a tapered rod, a pair of polarization separation surfaces and a reflection surface. Since the taper rod can be disposed in close contact with the light emitting surface of the light source, the light capturing efficiency is good. In addition, the taper rod uses multiple reflections on an inclined reflecting surface to bring the light beam closer to a beam parallel to the optical axis, and therefore has a better angle conversion efficiency than a collimator using a lens. The polarization conversion element is disposed in close contact with the tapered rod exit end, so that no loss of light can occur here. When the polarization conversion element is formed of two pairs of polarization separation surfaces and reflection surfaces that are symmetric with respect to the optical axis, the light quantity balance is more excellent. In addition, a minute gap is provided between the polarization separation surface and the reflection surface of the polarization conversion element, and the light beam that is about to pass through without passing through the polarization separation surface can be pulled back to the polarization separation surface. If the exit surface shape of the polarization conversion element is similar to the light valve surface, the light valve can be efficiently illuminated by the relay lens. Furthermore, if the LED light source is provided with a photonic crystal, the action of the photonic crystal and the action of the taper rod are synergistically overlapped to form an illumination system with higher light utilization efficiency. A method for improving the light utilization efficiency of the illumination optical system in such a projector apparatus has been found, and the following invention has been completed.

The present invention includes a light source, a tapered rod that emits light incident from the light source as a light beam, a polarization conversion element that receives and separates the light beam emitted from the taper rod, and a light beam that is polarized and separated by the polarization conversion element. The polarization conversion element has a polarization separation surface and a reflection surface that form parallel planes, and has a phase on the exit surface of either the transmitted light or the reflected light separated by polarization. An illumination optical system for a projector apparatus, comprising a modulation element, wherein the shape of the exit surface formed by the exit surface of the transmitted light and the exit surface of the reflected light is similar to the shape of the light incident surface of the light valve It is.

  Lighting optics for liquid crystal projectors with extremely high light utilization efficiency, including polarization conversion efficiency, by combining the tapered rod and the above-mentioned polarization conversion element to irradiate the light valve's incident surface as a polarized beam with the light emitted from the light source A system is formed. In addition, since the polarization conversion element has a polarization separation surface and a reflection surface forming parallel surfaces, only one taper rod for irradiating the polarization conversion element with a light beam is required, and an illumination optical system having a simple configuration can be obtained. . Furthermore, an illumination optical system with a simple configuration in which a transmissive liquid crystal panel is disposed immediately after the polarization conversion element as a light valve can be configured.

The present invention further has a configuration in which a lens that projects the shape of the exit surface of the polarization conversion element onto the light beam incident surface of the light valve is provided between the polarization conversion element and the light valve.

The present invention further between the polarization converter and the light valve, and has a configuration in which a rod integrator for projecting the shape of the exit surface of the polarization conversion element to the light beam incident surface of the light valve.

  By providing a lens or a rod integrator that projects the shape of the exit surface of the polarization conversion element onto the light beam incident surface of the light valve, the light beam can be efficiently projected onto the incident surface of the light valve. Further, by arranging the rod integrator after the polarization conversion element, the balance of the light amount is improved, and even if the polarization conversion element has a gap or the like and the light beam becomes non-uniform, it can be made uniform.

The present invention further includes a configuration in which the polarization conversion element includes two or more pairs of polarization separation surfaces and reflection surfaces that are symmetric with respect to the optical axis.

  By combining the taper rod and two or more pairs of polarization conversion elements that are symmetric with respect to the optical axis, an illumination optical system for a liquid crystal projector that has extremely high light utilization efficiency including polarization conversion efficiency and good illumination symmetry is formed.

The present invention further includes a configuration in which the light beam exit surface of the tapered rod and the incident surface of the polarization conversion element are in close contact with each other.

In the present invention, the polarization conversion element further includes a configuration in which a gap is provided at a position that blocks a light beam that is incident from the taper rod and transmits without reaching the polarization separation surface.
The present invention further includes a configuration in which the tapered rod has an array structure.
In the present invention, the tapered rod further includes a configuration in which a light beam is incident from both sides with respect to the polarization conversion element that is an optical axis target.
In a preferred aspect of the present invention, the illumination optical system of the projector apparatus is characterized in that the light source and the incident surface of the taper rod are each set to form an array structure.
The reference invention includes a light source, a tapered rod that emits light incident from the light source as a light beam, a polarization conversion element that receives and splits the light beam emitted from the taper rod, and is polarized and separated by the polarization conversion element. A light valve that modulates the light beam incident thereon, the polarization conversion element having a polarization separation surface and a reflection surface forming parallel surfaces, and emitting either one of the transmitted light and the reflected light separated by polarization. The surface is provided with a phase modulation element, and the shape of the exit surface formed by the exit surface of the transmitted light and the exit surface of the reflected light is substantially similar to the shape of the light incident surface of the light valve. A lens for projecting the shape of the exit surface of the polarization conversion element onto the light beam entrance surface of the light valve is provided between the bulb and the shape of the exit surface of the polarization conversion element is provided between the polarization conversion element and the light valve. Rye A rod integrator for projecting onto a light beam incident surface of a bulb, wherein the polarization conversion element has two or more pairs of polarization separation surfaces and reflection surfaces that are symmetric with respect to the optical axis, and the light beam emission surface and polarization conversion element of the tapered rod The polarization conversion element is provided with a gap at a position that blocks a light beam incident from a taper rod and transmitted without reaching the polarization separation surface, and the lens has a focal length ratio of An illumination optical system of a projector device, wherein the illumination optical system is a pair of lenses that are slightly larger than the ratio of the exit end size of the polarization conversion element and the size of the light valve.

  In a preferred aspect of the present invention, the polarization conversion element is characterized in that a gap is provided on a surface connecting the end of the incident surface of the light beam incident from the taper rod and the end of the polarization separation surface on the exit side of the polarization conversion element. The illumination optical system.

  By providing the gap as described above in the polarization conversion element, the light beam that is to be transmitted without reaching the polarization separation surface is reflected and irradiated to the polarization separation surface, so that an illumination optical system with higher light utilization efficiency can be obtained. Composed.

  In a preferred aspect of the present invention, the illumination optical system is characterized in that the light source is a light emitting diode (LED).

  In a preferred aspect of the present invention, the light source includes a photonic crystal.

  By including a photonic crystal in the light source, it is possible to improve the light utilization efficiency particularly in an illumination optical system using an LED light source.

  In a preferred aspect of the present invention, the light valve is a transmissive liquid crystal panel or a reflective liquid crystal panel.

  The present invention includes a plurality of the illumination optical systems, a dichroic prism that combines the light beams emitted from the polarization conversion elements in each illumination optical system, and a projection lens that projects the light beams emitted from the dichroic prism onto the screen A projector apparatus characterized by comprising:

  By installing the illumination optical system of the present invention, light utilization efficiency is improved, and a large-screen projector device can be realized even when a solid-state light source such as an LED is used.

  In a preferred aspect of the present invention, the projector apparatus is characterized in that a dichroic prism is disposed between the polarization conversion element and the light valve, and one light valve is shared for each illumination optical system.

  Even in a projector apparatus including a plurality of illumination optical systems, the configuration of the projector apparatus can be simplified by sharing a light valve or the like.

  In a preferred aspect of the present invention, the illumination optical system includes a plurality of the light sources, and a dichroic prism disposed between the light sources and the taper rod.

  In a preferred aspect of the present invention, the light source is a light source of three different colors, and the dichroic prism is a cross dichroic prism.

  A color illumination optical system with a simplified configuration can be obtained by color-combining light from light sources of three different colors in front of the taper rod.

  The present invention is a projector device comprising the illumination optical system and a projection lens that projects a light beam emitted from the illumination optical system onto a screen.

  According to the present invention, an illumination optical system with high light utilization efficiency capable of obtaining sufficiently bright projection light even with a light source with a relatively small amount of light such as an LED in a projector apparatus provided with a light valve, and the illumination optical system Can be provided.

  The best mode for carrying out the present invention will be described with reference to the drawings as necessary. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of a preferred embodiment of the present invention, and does not limit the scope of the claims.

(Embodiment 1)
FIG. 1 shows an illumination optical system according to Embodiment 1 of the present invention. The illumination optical system according to the first embodiment includes a light source 2 (LED), a taper rod 3, a polarization conversion element 4, lenses 6 and 7, and a light valve 8 (reflective or transmissive liquid crystal panel). As shown in FIG. 2, the LED is formed by arranging minute light emitting surfaces in an array (FIGS. 2A and 2C) or an enlarged one surface (FIGS. 2B and 2D). The tapered rod 3 has an incident end that is in close contact with the LED, has an incident end shape that is substantially the same size as the LED size, and an output end that is substantially similar to the shape obtained by dividing the incident surface of the liquid crystal panel 8 into two equal parts. (In the present application, a similar shape includes a congruent shape.), And the shape widens on the taper from the entrance end toward the exit end. The polarization conversion element 4 is shaped like a rectangular prism, and its exit surface is substantially similar to the entrance surface of the liquid crystal panel 8 (the aspect ratio is the same as the panel aspect ratio (so-called aspect ratio)) and its size. The vertical direction is twice the tapered rod exit end, and the lateral direction is the same size as the tapered rod exit end. In this embodiment, the incident end of the polarization conversion element 4 is in close contact with the exit end of the taper rod 3.

  The polarization conversion element 4 includes an inclined surface having an inclination of 45 ° with respect to the incident direction of the principal axes of the two parallel light beams. The first inclined surface is the polarization separation surface 4a, and the second inclined surface is It is a reflective surface 4b. The polarization separation surface 4a is disposed so as to cover the tapered rod exit end when viewed from the direction opposite to the incident direction of the main axis of the light beam. By doing in this way, all the light beams parallel to the principal axis that enter from the taper rod 3 reach the polarization separation surface 4a. On the other hand, the reflecting surface 4b is disposed only in a portion where the tapered rod exit end is not visible when viewed from the direction opposite to the incident direction of the main axis of the light beam. Since the polarization conversion element 4 in FIG. 2 has the same shape in the depth direction of the figure, the description will be made on the drawing. A polarization separation surface 4 a is arranged on the exit end side of the polarization conversion element 4 at an angle. The reflecting surface 4b is disposed on the exit end side of the polarization conversion element 4 at an angle of 45 ° from the lower end of the tapered rod exit end. By doing in this way, the transmitted light of the polarization separation surface 4a is emitted from the upper half of the emission surface of the polarization conversion element 4, and the reflected light of the polarization separation surface 4a is emitted from the lower half.

  The phase modulation element 5 is attached to the upper half of the exit surface of the polarization conversion element 4. The phase modulation element 5 is a λ / 2 plate, and phase-modulates the light beam transmitted through the polarization separation surface 4a. The phase modulation element 5 performs phase modulation on either the transmitted light path or the reflected light optical path to obtain polarized light having the same wavefront. Which of the polarized lights is aligned depends on the panel characteristics and the optical path configuration. It depends on.

  The lens is basically composed of a pair of lenses, and the focal length ratio thereof is the same as (or slightly larger than) the ratio between the exit end size of the polarization conversion element and the panel size. The size of the panel is not particularly limited, but a size of about 0.7 inches is assumed in reality.

  The light beam emitted from the LED generally has a spread close to a Lambertian distribution, but since the taper rod 3 is disposed in close contact, it is taken into the taper rod with almost no loss. A part of the light beam taken into the tapered rod goes out from the exit end as it is, but the other beams are reflected by the side wall, and the light beam having a large angle is multiple-reflected by the side wall. At each of these reflection steps, the light beam gradually approaches an angle parallel to the optical axis, so that the entire light beam is close to parallel to the optical axis at the tapered rod exit end.

  The light beam from the exit end of the tapered rod enters the polarization conversion element 4 and is separated into P-polarized light (transmitted light) and S-polarized light (reflected light) by the polarization separation surface 4a (first inclined surface). The P-polarized beam passes through the polarization separation surface 4a and is emitted as it is from the exit surface of the polarization conversion element 4. The S-polarized beam is reflected by the polarization separation surface 4a and then again by the reflection surface 4b (second inclined surface). Reflected and emitted in the same direction as the P-polarized beam. A phase modulation element 5 (λ / 2 plate) is stretched on the upper half of the exit surface of the polarization conversion element 4. P-polarized light is aligned with other polarization directions (in this case, S-polarized light). Looking at the beam on the exit surface of the polarization conversion element 4, the angle is made closer to the optical axis by the taper rod 3, the polarization direction is aligned by the polarization conversion element 4, and the light passes through the taper rod 3 and the polarization conversion element 4. An integration effect is applied between them, and the intensity distribution on the exit surface of the polarization conversion element is almost uniform (flat).

  The lenses 6 and 7 are so-called relay lenses, and the shape of the exit surface of the polarization conversion element having a flat light amount distribution is projected onto the incident surface of the liquid crystal panel 8 as it is. The projection size is determined by the focal length ratio of the lens. The actual illumination size is set to be slightly larger than the panel size because it is necessary to see room in the upper, lower, left and right sides of the panel. The lenses 6 and 7 are desirably telecentric on both sides in consideration of the uniformity of illumination on the projector screen and the illumination efficiency. Further, the position in the optical axis direction of the liquid crystal panel 8 is arranged at a position where the balance between light use efficiency and illuminance unevenness is the best depending on the position of the entire illumination optical system and the design of the lens.

  In addition, what is called “adhesion” expresses a state of approaching a range in which light utilization efficiency hardly changes as viewed optically. Also, “same size” represents equality of such a size that optical loss hardly occurs, as in “contact”.

  The LED may be one in which microchips are arranged in an array as shown in FIGS. 2A to 2D, or one in which one surface is enlarged. Further, the shape of the light emitting surface is not limited to a square, and may be a rectangle or other shapes. The shape of the light source 2 is appropriately determined from the shape of the subsequent taper rod 3 and the like in consideration of the light amount and the light utilization efficiency.

(Embodiment 2)
In the illumination optical system of the second embodiment, as shown in FIG. 3A, the projection magnification of the lenses 6 and 7 can be equal, reduced, or enlarged. The size is appropriately selected depending on the size of the LED to be used, the amount of light emitted, the size of the incident surface of the liquid crystal panel 8, and the like. Furthermore, although the number of lenses is preferably two in principle, it can be configured by one as shown in FIG. However, in this case, care must be taken because the peripheral light amount drop easily occurs. Moreover, it is good also as a 3 or more lens structure.

(Embodiment 3)
The illumination optical system of Embodiment 3 is the same as the illumination optical system of Embodiment 1 in terms of the overall configuration, but the structure of the polarization conversion element 4a is different. That is, as shown in FIG. 4, in this polarization conversion element 4a, the taper rod 3 is in close contact with the central portion of the light beam incident surface, and polarization separation is performed on both the upper and lower sides around the optical axis of the light beam from the taper rod 3. The surface 4a is formed at an angle of 45 ° to the optical axis. And the reflective surface 4b is arrange | positioned at the both sides. In other words, the polarization conversion element 4a constitutes the polarization conversion element 4a and the reflection surface 4b by two pairs of parallel surfaces symmetrical to the optical axis. Further, the phase modulation element 5 is arranged at a position facing the central part on the emission end side of the polarization conversion element 4 a and the emission surface of the taper rod 3.

  The polarization separation surface 4a of the polarization conversion element should ideally be 100% P-polarized light transmission and 100% S-polarized light reflection, but this is not the case with actual polarization conversion element materials. The transmittance is easy to drop. As a result, a difference occurs in the light amount distribution at the exit surface of the polarization conversion element between the P-polarized transmitted light exit side and the S-polarized reflected light exit side, which causes an upper and lower imbalance of the illuminance of the liquid crystal panel 8. As in this embodiment, the illuminance distribution is kept vertically symmetrical by arranging the pair of the polarization separation surface 4a and the reflection surface 4b of the polarization conversion element 4a symmetrical about the optical axis. The entire system is also symmetric with respect to the optical axis and is easy to configure. In this embodiment, the pair of the polarization separation surface 4a and the reflection surface 4b is arranged symmetrically in the vertical direction.

(Embodiments 4 and 5)
The illumination optical system of the fourth embodiment is the same as the illumination optical system of the first embodiment in terms of the overall configuration, but the structure of the polarization conversion element 4 is different. As shown in FIG. 5, the illumination optical system of Embodiment 4 has a crack-shaped gap 10 having a minute width at the center of the polarization conversion element 4. The gap 10 is formed parallel to the optical axis of the light beam as a surface connecting the lower end portion of the close contact portion with the emission surface of the taper rod 3 and the lower end portion of the polarization separation surface 4a. When there is no gap 10, as shown by the broken line shown in FIG. 5, there is a light beam that deviates from the effective optical path and reduces the light utilization efficiency, but if there is a gap 10 as shown in FIG. 5, Since such a light beam has a large incident angle, it is totally reflected by the gap 10 and returns to the effective optical path, and is used as an effective light beam, thereby improving the light utilization efficiency. However, the reflected light (S-polarized light) reflected by the polarization separation surface 4a is incident substantially perpendicular to the gap surface, and easily passes through the gap 10 because the incident angle is small. Then, like the first embodiment, the light is reflected by the reflecting surface 4 b and emitted from the polarization conversion element 4.

  The illumination optical system of Embodiment 5 is an illumination optical system in which the same gap as described above is provided in the polarization conversion element 4a of the illumination optical system of Embodiment 3. In this case, as shown in FIG. 6, the gap 10 is a surface connecting the lower end portion of the contact portion with the exit surface of the taper rod 3 and the lower end portion of the polarization separation surface 4 a, and the contact portion with the exit surface of the taper rod 3. Are formed in parallel with the optical axis of the light beam at two points on the surface connecting the upper end of the light beam and the upper end of the polarization separation surface 4a. Even if the shapes are different, the effect of the gap 10 is the same as that of the illumination optical system of the fourth embodiment.

  The minute gap 10 may be a streak and projected onto the liquid crystal panel 8 (and thus onto the projector screen), but the performance (projection resolution) of the relay lenses 6 and 7 is not so high, and the width of the gap 10 If it is made sufficiently small compared with the size of the polarization conversion element 4, it will not be a problem, and it can be avoided by the following method.

(Embodiment 6)
In the illumination optical system of the sixth embodiment, as shown in FIG. 7, a rod integrator 9 is arranged immediately after the polarization conversion element 4. By disposing the rod integrator 9 after the polarization conversion element 4, if there is a difference between the P-polarized light transmittance and the S-polarization reflectance, the light amount may be unbalanced depending on the emission position of the polarization conversion element 4, or the center and the peripheral There is a difference in illuminance. Further, when there is a gap in the polarization conversion element 4 as in the illumination optical systems of Embodiments 4 and 5, there is a possibility that streaks occur in the projected image. By disposing the rod integrator 9 at the subsequent stage of the polarization conversion element 4, the light beams can be mixed and made uniform, so that the light beam emitted from the rod integrator 9 solves these problems.

(Embodiment 7)
In the illumination optical system of the seventh embodiment, as shown in FIG. 8, a photonic crystal 11 is arranged on the LED surface as the light source 2. Although the photonic crystal 11 itself has a function of increasing the optical axis parallel component, it does not necessarily have a sufficient optical axis collimating effect when viewed as a projector light source. Therefore, by combining this with a taper rod, an illumination optical system with higher light utilization efficiency can be obtained.

FIG. 15 shows the radiation angle characteristics when the angle of the LED is converted by the lens system and when the angle is converted by the taper rod, compared to the case where there is nothing. In each case, the case where the LED emission has a Lambertian distribution and the case with a photonic crystal are shown. (The lens system and the taper rod are compared in the case where the angle conversion is performed while enlarging the same size LED twice. The lens system is a spherical lens, but the same applies to other lens systems. Later, a rectangular parallelepiped rod integrator is used to align the exit surface size with the taper rod.) If there is no solid line (-) or dotted line (-), the circle (○) indicates the angle conversion in the lens system, and the square. (□) shows the result of the angle conversion with the taper rod. In each case, the solid line and the thick line mark plot have a Lambert distribution, and the broken line and the thin line mark plot have a photonic crystal.
The tapered rod has a larger light quantity distribution near 0 ° and better angle conversion characteristics than the lens system. Further, the angle conversion characteristic is better with the photonic crystal than with the Lambert distribution. In particular, the combination of a taper rod and a photonic crystal has the highest effect of improving angle conversion characteristics.

(Embodiments 8 and 9)
As shown in FIG. 9, the illumination optical system according to the eighth embodiment has a configuration in which a transmissive liquid crystal panel is used as the light valve 8 and is arranged at the output end of the transmissive liquid crystal panel direct polarization conversion element 4. In this case, the light valve 8 can be configured without a lens that projects a light beam onto the incident surface. The panel is directly illuminated by setting the size of the exit surface of the polarization conversion element 4 to a size substantially matching the size of the transmissive liquid crystal panel 8 (+ peripheral margin). In reality, a slightly larger size is more practical in order to give a margin to the periphery.

  As shown in FIG. 10, the illumination optical system according to the ninth embodiment includes a rod integrator 9 disposed between the polarization conversion element 4 and the transmissive liquid crystal panel 8 of the illumination optical system according to the eighth embodiment. The transmissive liquid crystal panel 8 is illuminated with incident light. In any of the embodiments, the polarization conversion element 4 can be configured in the same manner as described above, whether it is the optical axis symmetric type described above or a type provided with a gap.

(Embodiment 10)
The tenth embodiment is a reflective liquid crystal (so-called LCOS) type full-color projector device using the illumination optical system described so far. As shown in FIG. 11, the projector device according to the tenth embodiment combines three illumination optical systems each having R (Red), G (Green), and B (Blue) LEDs. The projection light from the liquid crystal panel is synthesized by the cross dichroic prism and projected onto the screen by the projection lens. In order to increase contrast, polarizing plates are inserted before and after the panel.

(Embodiment 11)
The eleventh embodiment is a modification of the projector apparatus according to the tenth embodiment and is a configuration example of a projector apparatus having a single reflection type liquid crystal (so-called LCOS) panel as shown in FIG. The illumination optical system includes three systems of R (Red), G (Green), and B (Blue). A cross dichroic prism is disposed on the first relay lens and the second relay lens, and the first relay lens and the second relay lens are arranged. Three colors are combined between the relay and the second lens, and the second and subsequent lenses have a common optical path.

Embodiment 12
The projector device of Embodiment 12 is an example of a projector device using dichroic mirrors 12a and 12b as shown in FIG. As described above, a cross dichroic prism may be used for the synthesis of the three colors. However, since the first lens and the second lens have a sufficient distance, two dichroic mirrors 12a as shown in FIG. , 12b, which is cheaper and more flexible in arrangement.

(Embodiment 13)
As shown in FIG. 14, the thirteenth embodiment is a full-color illumination optical system in which three colors are synthesized by one illumination optical system. The illumination optical system of the thirteenth embodiment includes a cross dichroic prism 14 between the light source 2 and the taper rod 3, and R, G, and B LEDs are arranged on three surfaces of the dichroic prism 14, and each light beam is arranged. Are combined by the dichroic prism 14 to form a full-color light beam, which is incident on the taper rod 3, and the illumination optical system after the taper rod is the same as the illumination optical system described so far. In this embodiment, since the optical path is common, a different design for each color cannot be performed, but the configuration is remarkably simplified. If a projection lens for projecting emitted light onto the screen is arranged in this illumination optical system, a projector device can be obtained.

(Embodiment 14)
So far, in the configuration of each illumination optical system, the taper rod 3 has been described as one for each optical path, but it is not necessarily required to be one. As shown in FIGS. 17A, 17B, and 17C, the set of the LED 2 and the taper rod 3 can be arrayed. If the array is made, the shape of the taper rod becomes complicated, but the overall length can be shortened. Further, it is possible to make light beams incident on both sides of the optical axis symmetrical polarization conversion element 4. This may be improved when the light intensity balance is not good. In addition, since each LED 2 is separated, there is an effect that it is easy to avoid high temperature by dispersing heat generation.

Conceptual diagram of illumination optical system (a) Example of LED light emitting surface Conceptual diagram of illumination optical system (b) Conceptual diagram of illumination optical system (c) Conceptual diagram of illumination optical system (d) Conceptual diagram of illumination optical system (e) Conceptual diagram of illumination optical system (f) Conceptual diagram of illumination optical system (g) Conceptual diagram of illumination optical system (h) Conceptual diagram of illumination optical system (i) Conceptual diagram of the projector device (1) Conceptual diagram of projector device (2) Conceptual diagram of the projector device (3) Conceptual diagram of illumination optical system (j) Radiation angle characteristic graph of illumination optical system Conceptual diagram of illumination optical system (k) Conceptual diagram of the illumination optical system (l)

Explanation of symbols

1, 1a to 1k: illumination optical system 1R: red (R) illumination optical system 1G: green (G) illumination optical system 1B: blue (B) illumination optical system 2: light source 2R: LED light source (R)
2G: LED light source (G) 2B: LED light source (B)
3: Tapered rods 3a, 3b, 3c, 3d, 3e: Arrayed taper rod 4: Polarization conversion element 4a: Polarization separation surface 4b: Reflection surface 5: Phase modulation element 6: Lens 7: Lens 8: Light valve 9: Rod integrator 10: Gap 11: Photonic crystals 12a, 12b: Dichroic mirror 13: Lens 14: Dichroic prism 15, 15a, 15b: Fly eye lens 16: Fly eye lens 17: Aperture

Claims (11)

A light source, a tapered rod that emits light incident from the light source as a light beam, a polarization conversion element that injects and separates the light beam emitted from the taper rod, and a light beam that is polarized and separated by the polarization conversion element is incident and modulated With a light valve to
The polarization conversion element has a polarization separation surface and a reflection surface that form parallel planes, and includes a phase modulation element on either exit surface of the transmitted light or the reflected light that has undergone polarization separation. The shape of the exit surface formed with the exit surface of the reflected light is similar to the shape of the light incident surface of the light valve,
Between the polarization conversion element and the light valve, a lens that projects the shape of the exit surface of the polarization conversion element onto the light beam incident surface of the light valve,
Between the polarization conversion element and the light valve, a rod integrator that projects the shape of the exit surface of the polarization conversion element onto the light beam incident surface of the light valve,
The polarization conversion element has two or more pairs of polarization separation surfaces and reflection surfaces that are optically symmetric,
The light beam exit surface of the taper rod and the incident surface of the polarization conversion element are in close contact with each other,
The polarization conversion element is provided with a gap at a position that blocks a light beam that is incident from a taper rod and transmits without reaching the polarization separation surface,
The tapered rod has an array structure,
An illumination optical system of a projector device, wherein the taper rod causes a light beam to be incident on both sides of the polarization conversion element that is an optical axis target.   The illumination optical system of the projector apparatus according to claim 1, wherein the light source and the incident surface of the taper rod are each set to form an array structure.   2. The polarization conversion element according to claim 1, wherein a gap is provided on a surface connecting an end of the incident surface of the light beam incident from the taper rod and an end of the polarization separation surface on the exit side of the polarization conversion element. 3. An illumination optical system of the projector device according to 2.   The illumination optical system of the projector device according to claim 1, wherein the light source is a light emitting diode (LED).   The illumination optical system of the projector device according to claim 1, wherein the light source includes a photonic crystal.   6. The illumination optical system of a projector device according to claim 1, wherein the light valve is a transmissive liquid crystal panel or a reflective liquid crystal panel.   A dichroic prism comprising a plurality of the illumination optical systems according to any one of claims 1 to 6, and combining a light beam emitted from a polarization conversion element in each illumination optical system, and a light beam emitted from the dichroic prism And a projection lens that projects the image onto the screen.   8. The projector apparatus according to claim 7, wherein a dichroic prism is disposed between the polarization conversion element and the light valve, and one light valve is shared for each illumination optical system.   The illumination optical system for a projector apparatus according to claim 1, wherein a plurality of the light sources are provided, and a dichroic prism is disposed between the light sources and the taper rod.   The illumination optical system of the projector device according to claim 9, wherein the light source is a light source of three different colors, and the dichroic prism is a cross dichroic prism. 11. A projector apparatus comprising: the illumination optical system according to claim 9 ; and a projection lens that projects a light beam emitted from the illumination optical system onto a screen.

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