JP4658368B2 - Projection device - Google Patents

Projection device Download PDF

Info

Publication number
JP4658368B2
JP4658368B2 JP2001109950A JP2001109950A JP4658368B2 JP 4658368 B2 JP4658368 B2 JP 4658368B2 JP 2001109950 A JP2001109950 A JP 2001109950A JP 2001109950 A JP2001109950 A JP 2001109950A JP 4658368 B2 JP4658368 B2 JP 4658368B2
Authority
JP
Japan
Prior art keywords
light
color
light valve
dichroic
projection apparatus
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP2001109950A
Other languages
Japanese (ja)
Other versions
JP2002303932A (en
Inventor
佐敏 山内
和弘 藤田
Original Assignee
株式会社リコー
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社リコー filed Critical 株式会社リコー
Priority to JP2001109950A priority Critical patent/JP4658368B2/en
Publication of JP2002303932A publication Critical patent/JP2002303932A/en
Application granted granted Critical
Publication of JP4658368B2 publication Critical patent/JP4658368B2/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a projection apparatus that projects a color image on a screen, and in particular, means for separating unpolarized natural light and lamp light into three colors and controlling the polarization direction of each separated light, for example, liquid crystal By driving a light valve consisting of elements, the polarization direction is changed when passing through or reflecting the liquid crystal, and light switching control is performed to form three color images, respectively. The present invention relates to a projection apparatus that color-synthesizes the formed three-color images again and projects them as color images.
[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 is known, and various optical systems are realized in order to realize this liquid crystal projector at a smaller size and at a lower cost. Have been devised. Until now, improvements have been made by using transmissive liquid crystal elements, but liquid crystal projectors using reflective liquid crystal elements with higher resolution and higher efficiency have 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. 8 shows an operation principle 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. 8, when the S-polarized light selected by the polarizing beam splitter (PBS) 70 is totally reflected, it is converted to P-polarized light by the reflective liquid crystal element 71 and is transmitted through the polarizing beam splitter 70 to the 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 70. 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. 9 shows an example of a color composition method using a conventional transmissive liquid crystal element. In FIG. 9, three sets of liquid crystal panels 81, 82, 83 and condenser lenses 84, 85, 86 are arranged opposite to the three surfaces of the prism 80 on which cross dichroic films 80a, 80b are formed, and the remaining 1 A projection lens 87 is arranged facing the surface. Then, the illumination light of the polarization component in one direction is separated into three colors, and each is transmitted through the transmissive liquid crystal panels 81, 82, 83, and at that time, the light is switched. In this method, light of three colors is synthesized through the formed prism 80 and projected by the projection lens 87.
[0005]
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, an element that improves the polarization component in one direction is required. 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. A plurality of methods have been proposed as a method for converting the light supplied from the light source into a single polarized light. Currently, a method combining a polarization beam splitter (PBS) and a half-wave plate is adopted. (Japanese Patent Laid-Open No. 11-142792 etc.).
FIG. 10 shows a principle diagram of the conventional polarization converter. In FIG. 10, a polarization beam splitter array (PBS array) 88 is provided with a plurality of polarization separation films 89. The polarization separation film 89 transmits a P wave (P polarization) and an S wave (S polarization). The reflected S wave (S polarized light) is incident on the half-wave plate 90 and turned into a P wave (P polarized light) by turning the vibration direction by 90 °. ) Can be converted to P wave (P polarized light) and used effectively.
[0006]
As for the color separation method, various methods such as a method using a cross prism or a dichroic mirror have been proposed. Color using a laminated retardation film described in JP-T-11-504441 A disassembly and synthesis method has been proposed, and a new projector using the method is disclosed in USP 613091 and Nikkei Microdevices August 2000 p184.
[0007]
An outline of an embodiment of this prior art is shown in FIG. As shown in FIG. 11, this liquid crystal projector includes an illumination device (not shown), four polarization beam splitters (PBS) 91, 92, 93, 94, and three reflective liquid crystal panels 95 for green, red, and blue. 96, 97, two types of laminated retardation films (color polarizers) 98, 99, a polarizing plate 100, and a projection lens 101. Illumination light from an illuminating device (not shown) first enters the first laminated retardation film 98, and only the green band has its 90-degree polarization direction converted, and the first PBS 91 causes green and green complementary colors (magenta). The green is reflected by the second PBS 92 and modulated by the green liquid crystal panel 95. Magenta is changed in polarization direction by 90 degrees only in the red wavelength band by the second laminated retardation film 99, reflected by the third PBS 93, and incident on the red liquid crystal panel 96 to be modulated. Blue is transmitted through the third PBS 93 and is applied to the blue liquid crystal panel 97 to be modulated. Then, light of each color modulated by the liquid crystal panels 95, 96, and 97 for each color is combined via the fourth PBS 94, passes through the polarizing plate 100, and is projected by the projection lens 101.
Here, as described with reference to FIG. 8, the polarization direction is controlled by the liquid crystal panels 95, 96, and 97 to determine whether 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.
[0008]
The conventional example using the laminated retardation film as described above is a liquid crystal projector using a novel color separation method that has not been available so far, but because it uses many polarization beam splitters (PBS), It must be heavier.
In addition to the above configuration, a system using a PBS, a dichroic prism, and a spacer has been proposed.
[0009]
[Problems to be solved by the invention]
The projection apparatus having the above-described configuration has the following problems because color separation is performed using a laminated retardation film and PBS.
When the degree of polarization of incident light is low, color separation is not performed with high accuracy by polarized light components other than a desired polarized light component. That is, the color purity is lowered. In the conventional example, a linear polarizer is inserted into the incident light to maintain the color purity by using a means for improving the ratio of the desired polarization component. Will affect the color balance.
[0010]
Here, FIG. 12 is a diagram illustrating a problem that occurs when the degree of polarization becomes low in an optical system that performs color separation using a laminated retardation film and PBS.
In FIG. 12, for example, it is assumed that illumination light W having a ratio of P-polarized light to S-polarized light of 0.95: 0.05 is incident on the laminated retardation film 102. At this time, the laminated retardation film 102 is composed of the G / M type in which the polarization direction of only the green band (G band) is rotated by 90 degrees and the other bands (hereinafter referred to as M band) are transmitted without being converted. Then, after passing through the laminated retardation film 102, the G band is
P-polarized light: S-polarized light = 0.05: 0.95
And the M band is
P polarized light: S polarized light = 0.95: 0.05
It will have a polarization component. The light separated in the transmitting direction by the polarization beam splitter (PBS) 103 is mixed with a little G band color in most M band light having P polarization component. In addition, the light separated in the direction of reflection by the PBS 103 is such that most of the G band color having the S polarization component is mixed with the M band color.
As described above, in the optical system that performs color separation using the laminated retardation film and the PBS, there is a problem that the color purity is lowered when the polarization degree is lowered.
[0011]
The present invention has been made in view of the above circumstances, and solves the above-described problems in a projection apparatus using an optical system that performs color separation using a laminated retardation film and PBS, and is not affected by the degree of polarization of incident light. It is an object of the present invention to realize a projection apparatus that can project a high-quality image with high color purity and good color balance onto a screen.
[0012]
[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 a polarization direction, and means for efficiently illuminating the light valve with light from the light source. In the projection apparatus constituted by the means for projecting the image light modulated by the light valve, the illumination light from the light source is incident on the laminated retardation film, and the light after passing through the laminated retardation film The component light whose polarization direction does not change and the component light whose polarization direction has changed are divided into two by a polarization beam splitter, and one of the two divided lights is used as illumination light for the first light valve, The light is guided to the color separation element, separated into two colors by the color separation element, and the respective lights divided into the two colors are used as illumination light for the second and third light valves, Et by the third light valve to form a color image, and means for synthesizing the image light respectively modulated, characterized in that the image formed on a screen by the projection means, and, A color filter for removing color light other than the color light incident on the first light valve is disposed between the first light valve and the polarization beam splitter, and the second light valve, the color separation element, and / or Alternatively, color light other than the color light incident on the second and / or third light valve is removed between the third light valve and the color separation element. A color filter is arranged.
[0013]
The invention according to claim 2 is the projection apparatus according to claim 1, wherein a dichroic filter is used as the color filter.
The invention according to claim 3 is the projection apparatus according to claim 2, wherein a dichroic film is formed as the dichroic filter in at least one place on the illumination light exit surface of the color separation element. is there.
Furthermore, the invention according to claim 4 is the projection apparatus according to claim 2, wherein, as the dichroic filter, a polarization beam splitter that emits a light beam directed to the first light valve among the light beams divided into two by the polarization beam splitter. In this embodiment, a dichroic film is formed on the exit surface.
[0014]
The invention according to claim 5 is the projection apparatus according to any one of claims 1 to 4, wherein a total reflection prism is disposed between the first light valve and the polarization beam splitter. Is.
The invention according to claim 6 is the projection apparatus according to claim 5, wherein a dichroic film is formed on the total reflection surface of the total reflection prism.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration, operation and action of the present invention will be described in detail based on the illustrated embodiments.
[0016]
Example 1
FIG. 1 is a schematic configuration diagram of a projection apparatus showing an embodiment of the present invention. In FIG. 1, reference numeral 1 is a laminated retardation film, 2 is a polarization beam splitter (PBS) having a polarization separation film (PBS film) 2a therein, 3 is a dichroic prism having a color separation film (dichroic film) 3a inside, 4 is a color filter for green (G), 5 is a color filter for red (R), 6 is a light valve for green (G) (first light valve), and 7 is a light valve for red (R). (Second light valve), 8 is a light valve for blue (B) (third light valve), and 9 is a projection lens (projection lens).
Note that illustration of an illumination system such as a light source and means for using light from the light source as illumination light (for example, an integrator optical system, a condenser lens, etc.) is omitted.
[0017]
The projection apparatus shown in FIG. 1 includes a laminated retardation film 1 and PBS 2. The PBS film 2a of the PBS 2 transmits P-polarized light and passes S-polarized light out of the light after passing through the laminated retardation film 1. Reflect and separate into two colors. One of the two divided lights is used as illumination light for the first light valve 6, and the other is further separated into two colors by a color separation element, for example, the dichroic film 3a of the dichroic prism 3, and the second and third light valves 7 are separated. , 8 as illumination light.
A reflective liquid crystal panel or the like is used for the first to third light valves 6, 7, and 8. The first to third light valves 6, 7, and 8 change the polarization direction according to the video signal to form images of G, R, and B colors, and the modulated video light is again transmitted to the dichroic prism. 3. Synthesized after passing through PBS2. When the polarization direction is changed by the liquid crystal panels constituting the first to third light valves 6, 7, and 8, the image light modulated by each light valve 6, 7, and 8 passes through the PBS 2 and is a projection lens. 9 and projected onto a screen (not shown).
[0018]
Here, in the projection apparatus having the configuration shown in FIG. 1, the color filters 4 and 5 are arranged between the first light valve 6 and the PBS 2, between the second light valve 7 and the dichroic prism 3, and the like. (Claim 1).
The color filters 4 and 5 are color filters in which the principal wavelength components of each color corresponding to three colors as illumination light to each light valve (liquid crystal panel) have higher transmittance than other wavelengths. Alternatively, it is only necessary to have a characteristic that the transmittance of the complementary color of the color corresponding to the liquid crystal panel of each color is lowered. The complementary color transmittance is most effective when it is close to 0, but the color filter according to the present invention has a slight difference between the color transmittance corresponding to the liquid crystal panel and the transmittance of the complementary color. A filter is effective. As the color filter, various color filters such as a conventional colored glass and a gelatin filter can be used.
[0019]
In the above configuration, for example, in the case of the laminated retardation film 1 in which incident light is incident as S-polarized light and the polarization direction of only the green band light is changed, the green band is transmitted through the laminated retardation film 1. Becomes P-polarized light and travels toward the first light valve (liquid crystal panel) 6. Here, as described in the problem of the prior art, when the degree of polarization of the illumination light is low (in the case of this embodiment, the illumination light includes a little P-polarized component), the magenta of the P-polarized component Although the band is directed toward the green (G) light valve 6, it is possible to remove transmitted light other than green by the green filter 4 disposed in front of the green light valve 6. .
[0020]
In addition, the light that is mixed with the S-polarized light component having the magenta wavelength that is not converted by the laminated retardation film 1 and the green band of the P-polarized illumination light component is converted to S-polarized light and reflected by the PBS 2, For example, when the dichroic prism 3 separates red (R) and bands other than red, blue (B) is mixed with some green in the band other than red, but the light valve 8 for blue is used. By disposing a blue color filter (not shown) between the dichroic prism 3 and the dichroic prism 3, it is possible to reduce the transmitted light of the green component.
Further, when the dichroic prism 3 is used to separate blue (B) and bands other than blue, the red color filter 5 may be disposed between the red light valve 7 and the dichroic prism 3. Further, both blue and red color filters may be arranged.
[0021]
The laminated retardation film 1 is configured with the function of converting the polarization direction of the green (G) band. However, if the laminated retardation film 1 is configured by an element that converts the blue (B) band, the dichroic film 3a of the dichroic prism 3 of the embodiment is A film that separates red (R) and green (G) may be used.
Also, if the laminated retardation film 1 is composed of an element that converts the polarization direction of the red (R) band, the dichroic film 3a of the dichroic prism 3 is a film that separates the blue band and the green band. Good.
By adopting the configuration as described above, it is possible to realize a projection apparatus that does not reduce the color balance without reducing the color balance even with illumination light having a low degree of polarization.
[0022]
(Example 2)
Next, FIG. 2 is a schematic configuration diagram of a projection apparatus showing another embodiment of the present invention. In FIG. 2, reference numeral 11 is a laminated retardation film, 12 is a polarization beam splitter (PBS) having a polarization separation film (PBS film) 12a therein, 13 is an air gap, and 14 is a color separation film (dichroic film) 14a inside. 15 is a color filter for green (G), 16 is a color filter for blue (B), 17 is a light valve for green (G) (first light valve), and 18 is red (R ) Light valve (second light valve), 19 is a blue (B) light valve (third light valve), and 20 is a projection lens (projection lens). In this embodiment, the P-polarized light component is used as illumination light and is incident on the laminated retardation film 11. For example, only the green (G) band is converted into the S-polarized light component orthogonal to 90 degrees and incident on the PBS 12. The S-polarized light in the green band is reflected by 12a to be the illumination light of the first light valve 17, and the P-polarized light in the other band is transmitted through the PBS film 12a and incident on the dichroic prism 14, and the dichroic prism 14 The dichroic film 14a further separates the red (R) and blue (B) colors into illumination light for the second and third light valves 18, 19. In this embodiment, color filters 15 and 16 are disposed between the first light valve 17 and the PBS 12 and between the third light valve 19 and the dichroic prism 14.
Note that illustration of an illumination system such as a light source and means for using light from the light source as illumination light (for example, an integrator optical system, a condenser lens, etc.) is omitted.
[0023]
Here, in the configuration shown in FIG. 1, an example in which the dichroic prism 3 having the dichroic film 3a having the inclination of 45 degrees is shown, but the dichroic film of the dichroic prism is configured at any angle capable of color separation. can do. That is, when it is desired to adopt a configuration having no angle dependency, a shallower angle is effective. For example, a dichroic prism 14 separated by a dichroic film 14a having an angle of 30 degrees as shown in FIG. You may comprise by the dichroic prism isolate | separated by the dichroic film | membrane of an angle.
Further, instead of the dichroic prism, a flat plate type dichroic mirror or a filter may be used.
The laminated retardation film 11, PBS 12, dichroic prism 14, color filters 15, 16, and first to third light valves 17, 18, 19 are substantially the same as those in the first embodiment.
[0024]
(Example 3)
Next, FIG. 3 is a schematic configuration diagram of a projection apparatus showing another embodiment of the present invention. In FIG. 3, reference numeral 21 is a laminated retardation film, 22 is a polarization beam splitter (PBS) having a polarization separation film (PBS film) 22a inside, 23 is a dichroic prism having a color separation film (dichroic film) 23a inside, 24 is a parallel plate made of optical glass, 25 is a dichroic filter for blue (B), 26 is a dichroic filter for green (G), 27 is a light valve for green (G) (first light valve), 28 is a red (R) light valve (second light valve), 29 is a blue (B) light valve (third light valve), and 30 is a projection lens (projection lens).
Note that illustration of an illumination system such as a light source and means for using light from the light source as illumination light (for example, an integrator optical system, a condenser lens, etc.) is omitted.
[0025]
In this embodiment, the dichroic filters 25 and 26 are used as the color filters instead of the normal color filters described in the first and second embodiments (claim 2). Further, in the configuration of FIG. 3, in order to correct the optical path length of the light beam that illuminates the first light valve 27 after being separated by the PBS 22, the parallel plate 24 that corrects only the optical path length of the dichroic prism is the PBS 22 and the first In this embodiment, a dichroic filter 26 is disposed between the first light valve 27 and the parallel plate 24.
The dichroic filter can be formed on the surface of optical glass or the like using a recent thin film forming technique. Specifically, a dichroic film can be formed on the surface of optical glass or the like by a thin film forming technique in which a dielectric material or a metal material is formed in multiple layers using a vacuum process. By using the dichroic filters 25 and 26 as the color filter, it is possible to arbitrarily set the transmittance and reflectance of all wavelengths.
[0026]
The configuration, operation, and action of the projection apparatus of the present embodiment are substantially the same as the configuration, operation, and action of the projection apparatus of Embodiment 1 except that the dichroic filters 25 and 26 are used as color filters. Since the dichroic filters 25 and 26 according to the present invention can reflect the light flux in the band that should not be illuminated, the amount of the light flux in the unnecessary band reaching the light valve (liquid crystal panel) is reduced. Is possible. That is, the light that lowers the color purity is reflected by the dichroic filter before reaching the light valve (liquid crystal panel), and returns to the illumination light source by turning back the illumination optical path.
As described above, since the color filter is formed of a dichroic filter, a dichroic filter having an arbitrary spectral distribution characteristic can be disposed in front of the light valve.
In addition, the dichroic filter can be configured with a high transmittance of transmitted light having a wavelength that should be originally illuminated on the light valve, which cannot be realized by an absorption type like a conventional color filter.
[0027]
In the configuration shown in FIG. 3, dichroic filters 26 and 25 are arranged in front of the first light valve 27 for green and the third light valve 29 for blue. , 28, 29 may be inserted into any one or more of the three locations. Further, when the dichroic film 23a of the dichroic prism 23 is configured to be separated into red (R) and a band other than red, a little green is mixed with blue in the band other than red. However, by disposing the dichroic filter 25 having a high transmittance in the blue region between the blue light valve 29 and the dichroic prism 23, the transmitted light of the green component can be lowered.
When the dichroic prism 23 separates the blue (B) and bands other than blue, a dichroic filter having a high red transmittance may be disposed between the red light valve 28 and the dichroic prism 23.
[0028]
Example 4
Next, FIG. 4 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention. In FIG. 4, reference numeral 31 denotes a laminated retardation film, 32 denotes a polarization beam splitter (PBS) having a polarization separation film (PBS film) 32a therein, and 33 denotes an optical having a dichroic film 33a functioning as a filter on the illumination light exit surface. A parallel plate made of glass or the like, a dichroic prism 34 having a color separation film (dichroic film) 34a inside and a dichroic film 34b functioning as a filter at least at one place on the illumination light exit surface, and 35 is green (G ) Light valve (first light valve), 36 is a red (R) light valve (second light valve), 37 is a blue (B) light valve (third light valve), 38 Is a projection lens.
Note that illustration of an illumination system such as a light source and means for using light from the light source as illumination light (for example, an integrator optical system, a condenser lens, etc.) is omitted.
[0029]
In this embodiment, as the dichroic filter shown in Embodiment 3 (FIG. 3), a dichroic film 34b is formed in at least one place on the illumination light exit surface of the dichroic prism 34 (Claim 3).
Since the dichroic filter described in the third embodiment can be formed by a conventional thin film forming technique, the dichroic filter can be integrally formed on the emission surface of the dichroic prism 34, and when the dichroic film 34a of the dichroic prism 34 is formed. In addition, since the dichroic film (dichroic filter film) 34b according to the present invention can be formed by the same vacuum process, the cost can be further reduced and the optical system can be downsized. .
[0030]
Further, in the configuration of FIG. 4, the parallel plate 33 that is corrected by the optical path length of the dichroic prism is corrected with the PBS 32 in order to correct the optical path length of the light beam that illuminates the first light valve 35 after being separated by the PBS 32. In this embodiment, a dichroic film 33a is integrally formed on the illumination light exit surface of the parallel plate 33 facing the first light valve 35.
The parallel plate 33 is effective for keeping the color synthesis accuracy and high image quality by matching the optical path length.
[0031]
(Example 5)
Next, FIG. 5 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention. In FIG. 5, reference numeral 41 denotes a laminated retardation film, 42 denotes a polarization beam splitter (PBS) having a polarization separation film (PBS film) 42a therein, 43 denotes a color separation film (dichroic film) 43a inside and illumination A dichroic prism 44 having a dichroic film 43b functioning as a filter at least at one location on the light exit surface is formed on the exit surface of the PBS 42 from which the light beam directed to the first light valve out of the light beams divided into two by the PBS 42 is emitted. Dichroic membrane that functions as a filter, 45 is a light valve for green (G) (first light valve), 46 is a light valve for red (R) (second light valve), and 47 is blue (B) A light valve (third light valve) 48 is a projection lens (projection lens).
Note that illustration of an illumination system such as a light source and means for using light from the light source as illumination light (for example, an integrator optical system, a condenser lens, etc.) is omitted.
[0032]
In the present embodiment, the parallel plate 33 of the fourth embodiment (FIG. 4) is not used, and the PBS 42 emits a light beam directed to the first light valve 45 out of the light beams divided by the PBS 42 as a dichroic filter. A dichroic film 44 is integrally formed on the surface (claim 4).
Since the dichroic filter described in the third embodiment can be formed by a conventional thin film forming technique, the dichroic filter can be integrally formed on the exit surface of the PBS 42, and the dichroic film according to the present invention can be formed when the PBS is formed. Since the (dichroic filter film) 44 can be directly formed, the cost can be further reduced and the optical system can be downsized.
[0033]
(Example 6)
Next, FIG. 6 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention. In FIG. 6, reference numeral 51 denotes a laminated retardation film, 52 denotes a polarization beam splitter (PBS) having a polarization separation film (PBS film) 52a therein, 53 denotes a color separation film (dichroic film) 53a inside and illumination A dichroic prism having a dichroic film 53b that functions as a filter at least at one place on the light exit surface, 54 is a total reflection prism, 55 is a dichroic film that is formed on the illumination light exit surface of the total reflection prism 54 and functions as a filter, and 56 is Light valve for green (G) (first light valve), 57 for red (R) light valve (second light valve), 58 for light valve for blue (B) (third light valve) ) And 59 are projection lenses (projection lenses).
Note that illustration of an illumination system such as a light source and means for using light from the light source as illumination light (for example, an integrator optical system, a condenser lens, etc.) is omitted.
[0034]
In the present embodiment, a total reflection prism 54 is disposed between the first light valve 56 and the PBS 52 instead of the parallel plate 33 of the fourth embodiment (FIG. 4), and a filter is provided on the illumination light exit surface of the total reflection prism 54. The dichroic film 55 functioning as a film is formed (claim 5).
The parallel flat plate 33 of the fourth embodiment (FIG. 4) is effective for keeping the color path accuracy and maintaining the accuracy of color synthesis and high image quality, but in order to achieve further miniaturization, it is shown in FIG. As described above, it is better to use a prism shape and use total reflection. In FIG. 6, the total reflection surface of the prism 54 is 90 ° reflection direction due to reflection in the paper surface, but any angle may be used as long as the total reflection condition is satisfied, and the reflection direction may be various directions. Can be set.
By adopting such a configuration, the optical path can be efficiently bent in an arbitrary direction, and further downsizing can be realized. Further, by using the total reflection prism 54, the volume can be halved as compared with the parallel plate 33 of FIG. 4, the weight and volume can be reduced, and a smaller and lighter projection apparatus can be realized.
[0035]
(Example 7)
Next, FIG. 7 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention. In FIG. 7, reference numeral 61 denotes a laminated retardation film, 62 denotes a polarization beam splitter (PBS) having a polarization separation film (PBS film) 62a therein, 63 denotes a color separation film (dichroic film) 63a inside and illumination A dichroic prism having a dichroic film 63b functioning as a filter at least at one place on the light exit surface, 64 is a total reflection prism, 64a is a dichroic film formed on the total reflection surface of the total reflection prism 64, and 65 is green (G). Light valve (first light valve) 66, red (R) light valve (second light valve), 67 (blue) light valve (third light valve), 68 Projection lens (projection lens).
Note that illustration of an illumination system such as a light source and means for using light from the light source as illumination light (for example, an integrator optical system, a condenser lens, etc.) is omitted.
[0036]
In the present embodiment, a total reflection prism 64 is disposed between the first light valve 65 and the PBS 62 as in the sixth embodiment (FIG. 6). A dichroic is provided on the total reflection surface of the total reflection prism 64. A film 64a is formed.
By adopting such a configuration, even when the total reflection condition is not satisfied, depending on the film design, it can be formed as a dichroic mirror, and the degree of freedom of the optical system layout is further improved. Further, since the light in the unnecessary wavelength region incident on the first light valve 65 can be transmitted from the total reflection surface, the light does not return to the illumination side, and there is an effect of not generating unnecessary flare light. A high-quality projection apparatus can be realized.
[0037]
【The invention's effect】
As described above, in the present invention, a light source, a light valve having a function of changing the polarization direction, a means for efficiently illuminating the light valve with light from the light source, and the light valve are modulated. Component light whose polarization direction does not change among the light after the illumination light from the light source is incident on the laminated retardation film and passes through the laminated retardation film in a projection apparatus constituted by means for projecting image light Then, the component light whose polarization direction has changed is divided into two by the polarization beam splitter, one of the divided light is used as illumination light for the first light valve, and the other light is guided to the color separation element. The light is separated into two colors by the color separation element, and the respective lights divided into the two colors are used as illumination light to the second and third light valves. Color image forming, and a means for combining the respective modulated image light, characterized in that the image formed on a screen by the projection means, and, A color filter for removing color light other than the color light incident on the first light valve is disposed between the first light valve and the polarization beam splitter, and the second light valve, the color separation element, and / or Alternatively, color light other than the color light incident on the second and / or third light valve is removed between the third light valve and the color separation element. Since the color filter is arranged (Claim 1), the color filter can improve the color purity of the illumination light to each light valve by removing light outside the desired color band, and the degree of polarization of the incident light. Therefore, it is possible to realize a projection apparatus that can project a high-quality image with high color purity, good color balance, and no influence on the screen.
[0038]
Further, in the above projection apparatus, by using a dichroic filter as the color filter (Claim 2), it is possible to form by arbitrarily setting the transmittance and reflectance of all wavelengths.
Further, as the dichroic filter, a dichroic film is formed on at least one place of the illumination light exit surface of the color separation element (Claim 3), or, as the dichroic filter, among the light beams divided into two by the polarization beam splitter By forming a dichroic film on the exit surface of the polarization beam splitter from which the light beam going to the first light valve exits (Claim 4), the number of parts can be reduced, the manufacturing cost can be reduced, and the optical system can be downsized. Can be realized.
[0039]
In the above projection apparatus, by arranging the total reflection prism between the first light valve and the polarization beam splitter (Claim 5), the optical path can be efficiently bent in an arbitrary direction, and the optical system can be more efficiently operated. Miniaturization can be realized.
Furthermore, by forming a dichroic film on the reflection surface of the total reflection prism (Claim 6), even if the total reflection condition is not satisfied, it can be formed as a dichroic mirror depending on the film design, and the degree of freedom of optical system layout is increased. Will improve.
In addition, light in an unnecessary wavelength region that is incident on the first light valve can be transmitted from the total reflection surface, so that it does not return to the illumination side and does not generate unnecessary flare light. A quality projection apparatus can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a projection apparatus showing an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a projection apparatus showing another embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention.
FIG. 4 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention.
FIG. 5 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention.
FIG. 6 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention.
FIG. 7 is a schematic configuration diagram of a projection apparatus showing still another embodiment of the present invention.
FIG. 8 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. 9 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. 10 is a diagram illustrating still another example of the prior art, and is a configuration explanatory diagram of a polarization converter.
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 an explanatory diagram of a problem that occurs when the degree of polarization decreases in an optical system that performs color separation using a laminated retardation film and a polarizing beam splitter.
[Explanation of symbols]
1, 11, 21, 31, 41, 51, 61: Laminated retardation film
2, 12, 22, 32, 42, 52, 62: Polarization beam splitter (PBS)
2a, 12a, 22a, 32a, 42a, 52a, 62a: PBS membrane
3, 14, 23, 34, 43, 53, 63: Dichroic prism (color separation element)
3a, 14a, 23a, 34a, 43a, 53a, 63a: Dichroic film (color separation film)
4, 5, 15, 16: Color filter
6, 17, 27, 35, 45, 56, 65: First light valve
7, 18, 28, 36, 46, 57, 66: second light valve
8, 19, 29, 37, 47, 58, 67: Third light valve
25, 26: Dichroic filter
33a, 34b, 43b, 44, 55, 64a: Dichroic membrane (dichroic filter membrane)
54, 64: Total reflection prism

Claims (6)

  1. It comprises a light source, a light valve having a function of changing the polarization direction, means for efficiently illuminating the light valve with light from the light source, and means for projecting image light modulated by the light valve. In the projection device
    Illumination light from the light source is incident on the laminated retardation film, and the component light whose polarization direction does not change and the component light whose polarization direction changes among the light after passing through the laminated retardation film are converted by the polarization beam splitter. The light path is divided into two, one of the divided light is used as illumination light for the first light valve, the other light is guided to the color separation element, and is separated into two colors by the color separation element. Each of the divided lights is used as illumination light to the second and third light valves, a color image is formed by the first to third light valves, and the respective modulated video lights are combined; characterized by forming an image on a screen by the projection means, and, between the first light valve and the polarization beam splitter, remove color light other than the color light entering into the first light valve The color filter is disposed and incident on the second and / or third light valve between the second light valve and the color separation element and / or the third light valve and the color separation element. A projection apparatus comprising a color filter for removing color light other than color light to be emitted .
  2. The projection device according to claim 1,
    A projection apparatus using a dichroic filter as the color filter.
  3. The projection apparatus according to claim 2, wherein
    A projection apparatus comprising a dichroic film formed as a dichroic filter in at least one place on an illumination light exit surface of a color separation element.
  4. The projection apparatus according to claim 2, wherein
    A projection apparatus, wherein a dichroic film is formed on the exit surface of the polarization beam splitter from which the light beam directed to the first light valve out of the light beam divided into two by the polarization beam splitter is used as the dichroic filter.
  5. In the projection apparatus as described in any one of Claims 1-4,
    A projection apparatus comprising a total reflection prism disposed between a first light valve and a polarizing beam splitter.
  6. The projection apparatus according to claim 5, wherein
    A projection apparatus, wherein a dichroic film is formed on a total reflection surface of a total reflection prism.
JP2001109950A 2001-04-09 2001-04-09 Projection device Expired - Fee Related JP4658368B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2001109950A JP4658368B2 (en) 2001-04-09 2001-04-09 Projection device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2001109950A JP4658368B2 (en) 2001-04-09 2001-04-09 Projection device

Publications (2)

Publication Number Publication Date
JP2002303932A JP2002303932A (en) 2002-10-18
JP4658368B2 true JP4658368B2 (en) 2011-03-23

Family

ID=18961810

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2001109950A Expired - Fee Related JP4658368B2 (en) 2001-04-09 2001-04-09 Projection device

Country Status (1)

Country Link
JP (1) JP4658368B2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007058163A (en) 2005-07-27 2007-03-08 Ricoh Co Ltd Light source apparatus, optical modulation apparatus, display apparatus, light condensing lighting system and projection type color display apparatus

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000070376A1 (en) * 1999-05-14 2000-11-23 Colorlink, Inc. Optical system for producing a modulated color image
JP2001066434A (en) * 1995-05-23 2001-03-16 Board Of Regents Of The Univ Of Colorado Color polarizer

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001066434A (en) * 1995-05-23 2001-03-16 Board Of Regents Of The Univ Of Colorado Color polarizer
WO2000070376A1 (en) * 1999-05-14 2000-11-23 Colorlink, Inc. Optical system for producing a modulated color image

Also Published As

Publication number Publication date
JP2002303932A (en) 2002-10-18

Similar Documents

Publication Publication Date Title
EP2771734B1 (en) Tilted dichroic polarizing beamsplitter
US6113239A (en) Projection display system for reflective light valves
DE60216327T2 (en) Color management system
US5298986A (en) Video projection apparatus
JP3768381B2 (en) LCD projector
US6786604B2 (en) Projection system having low astigmatism
US6419362B1 (en) Liquid crystal projection apparatus
US7347562B2 (en) Two-panel liquid-crystal-on-silicon color management system
US6535256B1 (en) Color liquid crystal display device
US5580142A (en) Image forming apparatus and projector using the same
JP3622500B2 (en) Liquid crystal projector
US5777789A (en) Efficient optical system for a high resolution projection display employing reflection light valves
JP3444521B2 (en) Projection type image display device
US7237899B2 (en) Highly efficient single panel and two panel projection engines
US5621486A (en) Efficient optical system for a high resolution projection display employing reflection light valves
US6247816B1 (en) Optical system for projection displays using spatial light modulators
US6116739A (en) Color projection display apparatus
JP4514440B2 (en) Projection display device
TW460730B (en) Dual board Liquid crystal projection display
US6176586B1 (en) Projection display apparatus
US6490087B1 (en) Optical systems for reflective LCD's
EP1405528B1 (en) Projection system having low astigmatism
US6262851B1 (en) Double-pass projection displays with separate polarizers and analyzers
US6582081B2 (en) Projection display device
JP3611787B2 (en) Color image system and method

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20080325

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20100928

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20101119

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20101221

A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20101224

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140107

Year of fee payment: 3

LAPS Cancellation because of no payment of annual fees