JP4653327B2 - Lighting equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an illuminating device and a projection device using the illuminating device, and in particular, means for controlling the polarization direction, for example, by driving a liquid crystal element to convert the polarization direction when passing a liquid crystal. Used in projectors equipped with a light valve that can perform light switching control. Unpolarized light from a light source such as a lamp is used to illuminate the light valve after aligning the polarization direction in one direction in the optical path. Lighting equipmentIn placeRelated.
[0002]
[Prior art]
Conventionally, as a projection device, a liquid crystal projector capable of projecting a bright image with uniform illuminance and excellent color reproducibility has been known, and various optical systems for realizing the liquid crystal projector smaller and at a lower cost are known. Have been devised. Up to now, improvements have been made using transmissive liquid crystal elements, but liquid crystal projectors using reflective liquid crystal elements with higher resolution and higher efficiency have also been put into practical use.
An outline of a conventional projection apparatus uses an illumination system arranged such that light emitted from a light source is condensed on a diaphragm of a projection lens by a condenser lens immediately before a light valve made of a liquid crystal element (LCD). In general, the illumination light from this illumination system is separated into light of three primary colors of red (R), green (G), and blue (B) by a dichroic mirror for color display. After being modulated by the liquid crystal element, the optical system is composed again by the dichroic mirror and projected by the projection lens (projection lens).
[0003]
Conventionally, when a liquid crystal element is used as a light valve, polarized light is used. The illumination light is naturally polarized and contains polarization components in various directions. After improving the degree of polarization by aligning the polarization direction in one direction, the illumination light is separated into three colors, and each color corresponds to a panel. The liquid crystal element (liquid crystal panel) is irradiated.
Here, FIG. 9 shows the principle of operation of a light valve (liquid crystal light valve) using a liquid crystal element in a conventional reflective liquid crystal projector (reflective liquid crystal projector). As shown in FIG. 9, when the S-polarized light selected by the polarizing beam splitter (PBS) 30 is totally reflected, it is converted to P-polarized light by the reflective liquid crystal element 31 and is transmitted through the polarizing beam splitter 30, and is sent to a projection lens (not shown). In the case of all black, which is guided and not reflected, it is returned to the light source by the polarizing beam splitter 30. Therefore, three liquid crystal light valves corresponding to the three colors R, G, and B are used, and each reflected light is again color-combined using a dichroic mirror or the like, and an image is formed on a screen by a projection lens. This is a general configuration of the reflective liquid crystal projector.
[0004]
FIG. 10 shows an example of a color composition method using a conventional transmissive liquid crystal element. In FIG. 10, three sets of liquid crystal panels 41, 42, 43 and condenser lenses 44, 45, 46 are arranged opposite to the three surfaces of the prism 40 on which the cross dichroic films 40a, 40b are formed, and the remaining 1 A projection lens 47 is arranged facing the surface. Then, the illumination light of the polarization component in one direction is separated into three colors, and each of them is transmitted through the transmissive liquid crystal panels 41, 42, and 43. At that time, the light is switched, and the cross dichroic films 40a and 40b are formed. In this method, light of three colors is synthesized through the formed prism 40 and projected by the projection lens 47.
[0005]
Furthermore, a liquid crystal projector method using a new color separation method has been proposed (Nikkei Microdevice, August 2000, page 184).
An outline of this type of liquid crystal projector is shown in FIG. As shown in FIG. 11, the liquid crystal projector includes an illumination device (not shown), four polarization beam splitters (PBS) 51, 52, 53, 54, and three reflective liquid crystal panels 55 for green, red, and blue. , 56, 57, two kinds of color polarizers 58, 59, a polarizing plate 60, and a projection lens 61. Illumination light from an illuminating device (not shown) first enters the first color polarizer 58, and only the green band has its polarization direction converted by 90 degrees, and the first PBS 51 provides green and green complementary colors (magenta). The green is reflected by the second PBS 52 and modulated by the green liquid crystal panel 55. The magenta is changed in the polarization direction by 90 degrees only in the red wavelength band by the second color polarizer 59, reflected by the third PBS 53, and incident on the red liquid crystal panel 56 to be modulated. Blue is transmitted through the third PBS 53 and irradiated to the blue liquid crystal panel 57 to be modulated. Then, the light of each color modulated by the liquid crystal panels 55, 56, and 57 for each color is combined via the fourth PBS 54, passes through the polarizing plate 60, and is projected by the projection lens 47.
Here, as described with reference to FIG. 9, the polarization direction is controlled by the liquid crystal panels 55, 56, and 57 to determine whether the white or black display is directed to the projection lens side or returned to the illumination light source side. It is the structure controlled by.
[0006]
[Problems to be solved by the invention]
Since the projector (liquid crystal projector) using the conventional liquid crystal element as described above handles polarized light, it is essential to improve the polarization degree of illumination light. Since the light source is a naturally-polarized light source, even if an ideal polarizing plate and an analyzer are combined, only 50% of the light amount can be used in principle, assuming that a polarization component in one direction is extracted. Actually, when the transmittance is taken into consideration, the utilization rate of the light amount further decreases. Therefore, the light supplied from the light source is converted into a single polarized light. Several methods have been proposed for listing the light supplied from this light source into a single polarized light. Currently, a method combining a polarizing beam splitter (PBS) and a half-wave plate is used. (Japanese Patent Laid-Open No. 11-142792 etc.).
FIG. 12 shows a principle diagram of the conventional polarization converter. In FIG. 12, a polarization beam splitter array (PBS array) 70 is provided with a plurality of polarization separation films 71. The polarization separation film 71 reflects only S waves (S polarization) and transmits transmitted P waves ( P-polarized light is incident on the half-wave plate 72 and turns into 90-degree vibration direction to become S-wave (S-polarized light), so that the previously discarded P-wave (P-polarized light) can be used effectively. become.
[0007]
However, the polarization beam splitter (PBS) has a characteristic that it is difficult to obtain a good separation characteristic for a wide incident angle in the entire visible light region, or a polarization converter using an arrayed PBS and a fly-eye lens. In this case, the angle of incidence on the PBS is increased, and the polarization separation characteristics are degraded. In addition, due to miniaturization, the polarization separation characteristics of PBS are further deteriorated due to the angle of the illumination light beam itself. Therefore, in practice, components other than the unidirectional polarization component are mixed in the illumination light.
[0008]
Since the liquid crystal projector in practical use uses the polarization converter as described above, the proportion of linearly polarized light is not 100%, and components other than the unidirectional polarization component are mixed in the illumination light. End up. Such a polarization component is a factor that lowers the color balance and lowers the contrast. Therefore, in order to improve the color balance or improve the contrast, it is desirable to use only a unidirectional polarization component as illumination light.
[0009]
In the conventional projection apparatus (liquid crystal projector) having the configuration using the color polarizer as shown in FIG. 11, when illumination light having a random polarization direction is used, two colors separated by the first PBS 51 are used. There is a problem that the color purity of each other decreases. As a conventional example that solves this problem, for example, it has been proposed to use a color polarizer as disclosed in JP-T-11-504441.
[0010]
Here, as a configuration example of the color polarizer, a conventional example described in Japanese Patent Application Laid-Open No. 11-504441 will be described with reference to FIG. 13. The color polarizer includes a single polarizing film 81 and two or more succeeding ones. And a retarder stack 82. The retarder stack is a color-selective polarizer called a laminated retardation film. This color polarizer has a function of generating a complementary primary color polarized in an orthogonal direction by combining a linear polarizer and a laminated retardation film. Also, in Japanese Patent Application Laid-Open No. 11-504441, as shown in FIG. 13, the first linear polarizer 81 and two or more retarders are provided, and the polarizer 81 is continuously connected. A first retarder stack 82 arranged, and by selecting the number N of the retarders and the retardance and orientation of the retarders, the first additive mixed primary spectrum is along the first polarization axis. A color polarizer is proposed, characterized in that the first subtractive primary color spectrum of the transmitted and complementary color is transmitted along a second orthogonal polarization axis. Adopts a configuration in which linear polarizers are arranged before incidence, thereby further improving color purity.
[0011]
However, in order to further improve the degree of polarization in one direction, inserting a linear polarizer will cause a large problem in practical use for higher output and illuminance improvement in future projection apparatuses.
In recent years, projectors with higher brightness have been demanded, and xenon lamps and metal halide lamps have been put to practical use as light sources. Recently, ultra-high pressure mercury lamps have been developed and more efficient. An illumination light source is employed. In addition, the brightness is improved by increasing the power consumption and improving the output. For this reason, since the heat generated from these lamps is considerably high, optical components arranged close to the illumination light source are required to have heat resistance, but linear polarizers are relatively used as the illumination light source. Since it is arranged at a close position, the polarizer is thermally damaged. In general, many linear polarizers have been proposed as filters that transmit only one direction of polarization, called a polarizing filter, but since all are light absorption type polarizers, illumination light is stored as heat. There is a risk of destroying the function of the element, which is a problem to be solved in order to realize a high-quality and high-light quantity projection apparatus.
[0012]
Further, in the conventional examples described in Japanese Patent No. 303957, Japanese Patent Laid-Open No. 11-316356, etc., a polarization beam splitter is arranged after the polarization conversion element to illuminate the light valve. In the configuration of the conventional example, the polarization beam splitter is used to separate the illumination light and the projection light. Therefore, when the polarization component changes due to uneven density of the glass member generated in the polarization beam splitter, Due to the surface reflection of the beam splitter, the illumination light may reach the projection lens directly, and there is a problem that the contrast tends to be lowered.
[0013]
  The present invention has been made in view of the above circumstances, and in a lighting device used in a projection device having a liquid crystal element (light valve) using polarization direction conversion, the polarization direction of illumination light is aligned in one direction. The purpose is to provide a lighting system that has both functions and functions that do not absorb heat.TossThe
[0014]
[Means for Solving the Problems]
  As means for achieving the above object, the invention according to claim 1 is directed to a light source, a light valve having a function of changing the polarization direction, and illumination means for efficiently illuminating the light valve with light from the light source. When,A polarization converter;The light source and the illuminating means are used in a projection apparatus including a means for projecting image light modulated by the light valve.And polarization converterA polarization separation function that reflects only light in the first linear polarization direction and reflects light in the second linear polarization direction orthogonal to the first linear polarization direction. HavepluralPolarizerAfter passing through the polarization converterPlaced in the light pathEach of the plurality of polarizers has a configuration in which a polarization separation film is formed on a parallel plate, and a second polarizer is disposed on an optical path of reflected light from the first polarizer of the plurality of polarizers. HaveIt is characterized by that.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present inventionExamples of reference and examplesAbout composition, operation and actionRefer to the drawingThis will be described in detail.
  Figure 1Reference exampleIt is a schematic block diagram of the illuminating device which shows. The illuminating device shown in FIG. 1 includes a light source 1, a polarization converter 3 that efficiently converts the polarization direction into linearly polarized light, an illumination condensing element 4 that efficiently illuminates a light valve (not shown), and polarization separation. The linear polarizer 5 has a function. The linear polarizer 5 passes light in the first linear polarization direction (for example, P polarization component), and reflects light in the second linear polarization direction (for example, S polarization component) orthogonal to the first linear polarization direction. It is a non-absorbing polarizer.
[0022]
In FIG. 1, a halogen lamp, a xenon lamp, a metal halide lamp, an ultra-high pressure mercury lamp, or the like is used as the light source 1, but a parabolic surface or an elliptical surface is provided on the back side of the light source 1 so that illuminance can be obtained efficiently. It is good also as a structure which arrange | positions the reflector 2 which has, and reflects and condenses the light of the light source 1 with the reflector 2. FIG.
The polarization converter 3 is composed of a polarization converter combining a PBS array and a wave plate as shown in the conventional example of FIG. 12, and the light from the light source 1 is efficiently converted into one polarization direction. Further, if necessary, a configuration combined with a lens array matched to the pitch of the PBS array is adopted.
[0023]
  The light condensing element 4 for illumination is a condensing element that reduces unevenness of illumination light irradiated to the light valve by combining a fly-eye lens called an integrator, or the light condensing element to the light valve in combination with a condenser lens. It may be a condensing element that leads efficiently.
  The non-absorbing linear polarizer 5 has a function of passing light in the first linear polarization direction and reflecting light in the second linear polarization direction orthogonal to the first linear polarization direction. 1 is a polarizing beam splitter that transmits a P-polarized light component that is a polarized light component on the plane of the paper, and reflects an S-polarized component in a direction orthogonal to the linearly polarized light component (normal direction of the paper surface). (PBS)The
[0024]
  In addition, in the illumination apparatus having the configuration shown in FIG. 1, after being converted into a unidirectional polarization component using the polarization converter 3, the polarization component that has not been converted, that is, the polarization component light that reduces the contrast, By disposing the polarizer 5 of the present invention behind the polarization converter 3, it is possible to remove it from the illumination light.TheThat is, in the configuration of FIG. 1, the light from the light source 1 is converted into P-polarized component light by the polarization converter 3, and then incident on the polarizer 5 through the illumination condensing element 4. The light is transmitted through the polarizer 5 as illumination light, and the S-polarized component light that could not be converted is reflected by the polarizer 5 and removed from the illumination light.
[0025]
  Here, a polarization separation function that transmits light in the first linear polarization direction (P-polarization component) and reflects light in the second linear polarization direction (S-polarization component) orthogonal to the first linear polarization direction is provided. As the polarizer 5, a polarizer such as a Wollaston prism using a birefringent optical material, for example, calcite, a Gran-laser prism, or the like can be used. Polarizing beam splitters using these crystal materials have angles for transmitting transmitted light and reflected light according to their characteristics, and are not necessarily configured with a 45 degree plane as shown in the figure. Set the illumination system layout according to the emission direction.
  As shown in FIG.Reference exampleAs an example, a diagram in which transmitted light and reflected light are separated in a direction of 90 degrees is illustrated. The transmitted light of the P-polarized component transmitted through the polarizer 5 is used as the illumination light.
[0026]
  As the polarizer 5 used in the illumination device having the configuration shown in FIG. 1, since a crystal material is expensive and not suitable for mass production, a thin film formation technique using a vacuum process using a dielectric material or a metal material is used. If it is composed of a polarizing beam splitter with an optical thin film (for example, a polarization separation film), a polarizer suitable for mass production can be realized at a lower cost.The
[0027]
With the configuration as described above, the polarized light component that has not been completely aligned with the polarized light component in one direction by the polarization converter 3, that is, the polarized light component that lowers the contrast is converted from the illumination light by the polarizer 5 of the present invention. It can be removed. In addition, the polarizer 5 of the present invention has a function of transmitting the necessary polarization component of the illumination light and reflecting the other polarization component. In the selective polarizer that absorbs the polarization component of the direction, it is possible to suppress heat generation due to light energy absorption, which is a problem, and to increase the output of the light source, so that brighter illumination can be performed it can.
[0028]
In the conventional example of FIG. 9, as a function of the liquid crystal element in the reflective liquid crystal projector, a polarizing beam splitter is disposed in front of the reflective liquid crystal element, and light having a higher degree of polarization is transmitted to the liquid crystal element by the polarizing beam splitter. However, with such a configuration, a polarizing beam splitter is required for each liquid crystal element, and there is a disadvantage that the cost is increased and the weight is increased. However, in the configuration of the present invention, white light before color separation is obtained. By arranging the polarizing beam splitter as the polarizer 5 in the illumination optical path, there is an advantage that it is not necessary to prepare a polarizing beam splitter corresponding to each color.
[0029]
  The configuration of the illumination device shown in FIG. 1 is a configuration using the polarization converter 3, but of course, there may be no polarization converter.ConfigurableThe That is, light from the light source 1 that is not polarized is incident on the polarizer 5 having a polarization separation function, thereby separating light in the first linear polarization direction and light in the second linear polarization direction. Therefore, the efficiency is less than half, but it is possible to obtain a polarization component having a high extinction ratio with respect to the orthogonal polarization component intensity without using the polarization converter 3, thereby reducing the light valve. Illumination with a unidirectional polarization component is possible.
[0030]
  Moreover, only the illumination light is allowed to pass through the polarizer 5 and only the illumination light is allowed to pass, and a polarization beam splitter or the like is not disposed in the optical path of the projection lens, so that a polarization beam that is a problem in the conventional example is obtained. It is possible to eliminate problems such as polarization components changing due to uneven density of members generated in the splitter, etc., and illumination light reaching the projection lens directly due to surface reflection of the polarizing beam splitter, etc. It becomes possible to prevent the decrease in contrastThe
[0031]
  By the way, shown in FIG.Reference exampleIn the above description, the polarizer 5 is composed of a polarization beam splitter in which a polarization separation film is formed by a thin film formation technique using a vacuum process using a dielectric material, a metal material, or the like. A polarization separation element having a configuration in which a polarization separation film is formed on a parallel plate by a film forming technique and a polarization separation film design technique can also be used as a polarizer.
  Here, FIG. 3 and FIG.RebetsuofReference exampleFIG. 2 is a schematic configuration diagram of the illuminating device with the same reference numerals as those in FIG. 1 being the same constituent members. As shown in FIG.Reference exampleThen, as a polarizer, a plate-type polarization beam splitter 6 having a polarization separation film formed on the surface of a parallel plate is used, and P-polarized light is transmitted and S-polarized light is reflected. Also, depending on the thin film design technology, as shown in FIG.Reference exampleAs described above, a configuration using a plate-type polarizing beam splitter 7 having a configuration in which a polarization separation film is sandwiched between two flat glass members as a polarizer is also possible. With such a configuration, it is possible to configure the polarization beam splitter with a glass substrate that is as low as possible. Moreover, by using flat glass, it becomes possible to reduce the influence of the density unevenness of a glass member, etc. as much as possible, and it can also prevent that a polarization component changes.
[0032]
  More thanReference exampleIn the description, the transmitted light (P-polarized polarization component) separated by the polarizer 5 (or 6 or 7) is used as illumination light.Reference exampleHas been explained, but by providing multiple polarizers,Reference exampleIn addition, it is possible to obtain illumination light with higher polarization purity.
[0033]
  Next, FIG.Another reference exampleFIG. 2 is a schematic configuration diagram of the illuminating device with the same reference numerals as those in FIG. 1 being the same constituent members. thisReference exampleThen, the optical system of the illumination device is arranged in the vertical direction, and only the polarization component of S-polarized light obtained by reflection by the polarization beam splitter which is the polarizer 5 is used as illumination light.TheThe functions and actions of other components are the same as those described above.Reference exampleIn the configuration of FIG. 2, the polarization converter 3 functions to convert the light from the light source 1 into S-polarized light.
[0034]
  Next, FIG.HasaAnotherReference exampleAnd a plurality of polarizers (polarized beam splitters) 8 and 9 are provided after the illuminating condensing element 4 and reflected by the plurality of polarized beam splitters 8 and 9. In this example, only the polarization component of polarized light is used as illumination light.
  nextFIG. 6 shows the present invention.The fruitIt is a schematic block diagram of the illuminating device which shows an Example, and after the light condensing element 4 for illumination, a plurality of polarizers (plate-type polarization beam splitters) 10 and 11 having a configuration in which a polarization separation film is formed on a parallel plate are provided, This is an example in which only S-polarized light components obtained by being reflected by a plurality of plate-type polarization beam splitters 10 and 11 are used as illumination light. 5 and 6, the functions and operations of the other components are as described above.Reference example5 and 6, the polarization converter 3 functions to convert light from the light source 1 into S-polarized light. In the case of a configuration in which the light of the polarization component reflected by the polarizer is used as illumination light, a plurality of polarizers are used as shown in FIGS. 5 and 6, and the light is reflected a plurality of times by the plurality of polarizers. Further, the degree of polarization can be improved.
[0035]
  The structure as shown in FIG. 2, FIG. 5 or FIG.To completeBy employing the optical path, the volume of the optical system can be further reduced by bending the optical path, and a smaller optical system can be realized. Thereby, the size of the projection apparatus can be reduced. 5 and 6 show a configuration in which the optical path is bent on the same paper surface, the optical system can be arranged in three dimensions by a plurality of reflections, and the volume can be reduced. Moreover, it is also possible to perform illumination with a higher degree of polarization as a configuration combining transmission and reflection.
[0036]
  As described above, the lighting device having the configuration according to the present invention.Reference examples andAlthough the embodiment has been described, by using this illumination device, by combining the light valve having a function of changing the polarization direction and the projection lens that projects the image light modulated by the light valve, the projection device is configured, A projector with high contrast can be realized. In addition, when used in a color projection device, a projection device with good color balance can be realized. In addition, the polarizer used in the illumination device is not a type of polarizer that absorbs light of a polarization direction component other than one direction, so that the portion where light energy is converted into heat can be reduced. It becomes possible to increase the output of the light source. Thereby, a brighter projection apparatus can be realized. Furthermore, the function of a reflecting mirror is added by applying an illumination device that uses light reflected by a polarizer as shown in FIG. 2, FIG. 5, or FIG. Therefore, it is very advantageous for downsizing of the apparatus.
[0037]
  Next, another according to the present inventionreferenceThe embodiment is shown in FIGS.Reference exampleBased on
  thisreferenceIn the embodiment, a light source such as a xenon lamp, a metal halide lamp, an ultra-high pressure mercury lamp, or a halogen lamp, a light valve (for example, a liquid crystal element) having a function of changing the polarization direction, and light from the light source to the light valve. The first linear polarization direction of the unpolarized light from the light source in a projection apparatus composed of means for efficiently illuminating the light (for example, an integrator optical system, a condenser lens, etc.) and a projection lens for projection A polarizer having a polarization separation function that transmits light in the second direction and reflects light in the second linear polarization direction orthogonal to the first linear polarization direction (for example, a polarization separation film composed of a metal or a dielectric multilayer film) Polarization beam splitter, etc.) and P-polarized component obtained by transmitting the polarizer, or obtained by reflecting the polarizer The S-polarized light component is used as illumination light, and the illumination light is incident on a color-selective polarizer (retarder stack or laminated retardation film) and passes through the color-selective polarizer. Later, a component of a wavelength band in which the polarization direction changes and a component light in a wavelength band in which the polarization direction does not change are generated, and this light is separated using a color separation means that divides the optical path by the second polarization beam splitter. Each light beam is used as illumination light to the light valve.
[0038]
  FIG.Reference exampleNumeral 12 is a first polarization beam splitter (PBS prism) having a polarization separation film (PBS film) 12a made of metal, a dielectric multilayer film or the like, and 13 is color selectivity. Polarizer (retarder stack or laminated retardation film), 14 is a second polarization beam splitter (PBS prism) having a polarization separation film (PBS film) 14a made of metal or a dielectric multilayer film, and 15 is an air gap. , 16 is a dichroic prism having a dichroic film 16a, 17 is a light valve (liquid crystal element) for green (G), 18 is a light valve (liquid crystal element) for red (R), and 19 is a light valve for blue (B). A bulb (liquid crystal element) 20 is a projection lens, which uses a high-purity P-polarized light component as illumination light, and is a color-selective polarizer 1. To be incident on, for example, it shows a configuration example in the case of using the element for converting the S-polarized light components perpendicular to only 90 degrees band of green. Although the illustration of the light source and the illumination means is omitted, the configuration of the illumination system including the first PBS prism 12 is the same as that shown in FIG.
[0039]
  In addition, FIG.Another reference exampleNumeral 21 is a plate-type polarization beam splitter (plate-type PBS) having a polarization separation film (PBS film) 21a composed of metal, a dielectric multilayer film or the like, and 22 is color selectivity. Polarizer (retarder stack or laminated retardation film), 23 is a second polarization beam splitter (PBS prism) having a polarization separation film (PBS film) 23a made of metal or dielectric multilayer film, and 24 is a dichroic film. A dichroic prism 24a, 25 is a light valve (liquid crystal element) for green (G), 26 is a light valve (liquid crystal element) for red (R), and 27 is a light valve (liquid crystal element) for blue (B). , 28 is a projection lens that reflects S-polarized light by a plate type PBS 21 and enters a color-selective polarizer 22. So, for example, it shows a configuration example of a case of using a device for converting and transmitting only band of green P polarized light component. Although the illustration of the light source and the illumination means is omitted, the configuration of the illumination system including the plate type PBS 21 is the same as that shown in FIG.
[0040]
  In the configuration of FIG. 7 (or FIG. 8), the green (G) light irradiates the green light valve 17 (25). In addition, the color-selective polarizer 13 (22) transmits the light without polarization conversion.TheSince the incident light is a magenta component other than green, this light beam is separated into red (R) and blue (B) wavelength bands by the dichroic film 16a (24a) of the dichroic prism 16 (24). The light valves 18, 19 (26, 27) corresponding to the respective colors are irradiated. If a reflective liquid crystal element is used for each of the R, G, and B light valves, the reflected light of each color travels through a double path that reverses the illumination light path. When the polarization direction is changed by the light valve, the reflected light (video light) of each color is synthesized by the second PBS prism 14 (23) and heads toward the projection lens 20 (28). It is projected on the screen by the projection lens 20 (28). In this way, the projector (liquid crystal projector) is configured.The
[0041]
  Here, FIG. 7 shows an embodiment of a projection apparatus having a configuration using a dichroic prism 16 having a dichroic film 16a having an angle of 30 degrees. FIG. 8 shows a configuration using a dichroic prism 24 having a dichroic film 24a having an angle of 45 degrees.Reference exampleIs shown. Instead of the dichroic prism, a configuration using a flat plate type dichroic mirror, a filter, or the like may be used.
[0042]
  In FIG. 7 (or FIG. 8), the color-selective polarizer 13 (22) is configured with the function of converting the polarization direction of the green (G) band, but the color-selective polarizer 13 (22) is blue. When it is configured with an element that converts the band of (B),Reference exampleThe dichroic film 16a (24a) may be a film that separates red (R) and green (G). When the color-selective polarizer 13 (22) is composed of an element that converts the red (R) band, the dichroic film 16a (24a) separates the blue (B) and green (G) bands. What is necessary is just to make it a film.
  Further, in order to accurately adjust the back focus of the G light valve 17 (25) shown in FIG. 7 (or FIG. 8) and the projection lens 20 (28) of the light valves 18, 19 (26, 27) of other colors. Furthermore, if a parallel plate equivalent to the thickness of the dichroic prism 16 (24) is inserted in front of the G light valve 17 (25) to reduce the chromatic aberration, a higher quality projection device can be realized. it can.
[0043]
  When using the color selective polarizer 13 (22), if the polarization degree of the incident light is low, the color separation performance is reduced, the color balance is lowered, and the contrast is lowered.Configuration of the above reference exampleThen, by inserting a polarizer having a polarization separation function that transmits light in the first linear polarization direction and reflects light in the second linear polarization direction orthogonal to the first linear polarization direction, into the illumination optical path. Because the illumination light is made using only the polarization component of the first or second linear polarization direction obtained by the polarizer, illumination with a very high degree of polarization is performed, so that illumination with high color purity is realized. it can. Further, by adopting this configuration after the polarization converter, more efficient illumination is possible.
[0044]
【The invention's effect】
As described above, according to the present invention, in the illumination device used in the projection device having the configuration including the liquid crystal element (light valve) using the polarization direction conversion, the function of aligning the polarization direction of the illumination light in one direction. In addition, it is possible to realize an illumination system illumination device having a function that does not generate absorption heat. Accordingly, it is possible to increase the output of the light source and provide an illumination device that can perform brighter illumination.
In addition, according to the present invention, an illumination-type illumination device having a function of aligning the polarization direction of illumination light in one direction and a function that does not absorb and generate heat is used to project a high-quality, large-intensity image. It is possible to realize a projection device that can.
[Brief description of the drawings]
[Figure 1]Reference exampleIt is a schematic block diagram of the illuminating device which shows.
[Figure 2]AnotherofReference exampleIt is a schematic block diagram of the illuminating device which shows.
[Fig. 3]TheAnotherReference exampleIt is a schematic block diagram of the illuminating device which shows.
[Fig. 4]TheAnotherReference exampleIt is a schematic block diagram of the illuminating device which shows.
[Figure 5]TheAnotherReference exampleIt is a schematic block diagram of the illuminating device which shows.
FIG. 6The fruitIt is a schematic block diagram of the illuminating device which shows an Example.
[Fig. 7]TheAnotherReference exampleIt is a schematic principal part block diagram of the projector which shows this.
[Fig. 8]TheAnotherReference exampleIt is a schematic principal part block diagram of the projector which shows this.
FIG. 9 is a diagram illustrating an example of a conventional technique, and is an explanatory diagram of functions of a reflective liquid crystal element in a reflective liquid crystal projector.
FIG. 10 is a diagram illustrating another example of the prior art, and is an explanatory diagram of a color composition method using a transmissive liquid crystal element.
FIG. 11 is a diagram showing still another example of the prior art, and is a schematic configuration diagram of a main part of a projection apparatus using a color polarizer.
FIG. 12 is a diagram illustrating still another example of the prior art, and is a configuration explanatory diagram of a polarization converter.
FIG. 13 is a diagram illustrating still another example of the prior art and is a configuration explanatory diagram of a complementary color polarizer.
[Explanation of symbols]
  1 Light source
  2 reflector
  3 Polarization converter
  4 Light collecting element
  5 Polarizing beam splitter (polarizer)
  6 Plate-type polarizing beam splitter (polarizer)
  7 Plate-type polarizing beam splitter (polarizer)
  8 First polarization beam splitter (polarizer)
  9 Second polarization beam splitter (polarizer)
  10 First plate-type polarizing beam splitter (polarizer)
  11 Second plate-type polarizing beam splitter (polarizer)
  12 First polarization beam splitter (polarizer)
  13 color selective polarizer
  14 Second polarization beam splitter
  15 Air gap
  16 Dichroic prism
  17 Light bulb for green
  18 Light bulb for red
  19 Light valve for blue
  20 Projection lens
  21 Plate-type polarizing beam splitter (polarizer)
  22 color selective polarizer
  23 Polarizing beam splitter
  24 dichroic prism
  25 Light bulb for green
  26 Light bulb for red
  27 Light Bulb for Blue
  28 Projection lens

Claims (1)

Projecting image light modulated by the light source, a light valve having a function of changing the polarization direction, illumination means for efficiently illuminating the light valve with light from the light source, a polarization converter, and the light valve In the illumination device comprising the light source, the illumination means, and the polarization converter ,
Among the light from the light source, a plurality of polarizers having a polarization separation function that passes only light in the first linear polarization direction and reflects light in the second linear polarization direction orthogonal to the first linear polarization direction , Arranged in the illumination optical path after passing through the polarization converter ,
Each of the plurality of polarizers has a configuration in which a polarization separation film is formed on a parallel plate,
A lighting device, wherein a second polarizer is disposed on an optical path of reflected light from the first polarizer of the plurality of polarizers .

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