JP2002139701A - Projector and projection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection method and projector with which the relations between plural LCDs(liquid crystal displays) and optical systems can be arranged with good accuracy by fastening PBSs(polarization beam splitters) and DPs(dichroic prisms). SOLUTION: PBS prisms separate incident light to S polarized light and P polarized light and output the same. In the DPs, the separated light rays are further separated to the light rays of two wavelength bands in dichroic films. The LCDs rotate, 90 deg.C, the light rays separated by the dichroic films of the DPs based on electrical signal or the polarization direction of the separated light rays and reflect these light rays. The PBSs are so arranged that, when the polarized light of either the S polarized light or the P polarized light is made incident thereon, the incident S polarized light or P polarized light is guided to the DPs and, when the random light rays are made incident thereon, the polarized light of either one of the S polarized light or the P polarized light is guided to the DPs. The PBSs and the DPs are so installed that air layers are not disposed therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a projection apparatus and a projection method for a liquid crystal projector that use a polarizing beam splitter (hereinafter, referred to as PBS) and a dichroic prism (hereinafter, referred to as DP) to improve light use efficiency. .

[0002]

2. Description of the Related Art Hitherto, a liquid crystal projector using a light valve, which is a display device suitable for illumination by a projection device having a PBS and a DP, has been used.
Incidentally, JP-A-63-39294 discloses a PBS.
(Polarizing beam splitter) and DP (Dicloic prism), incident light is reflected by PBS polarization splitting film, only S polarized light is guided to light valve through DP, and the S polarized light is modulated to P polarized light according to image signal. A video projection apparatus is described which returns the PBS together with the unmodulated S-polarized light through the DP to the PBS, reflects the S-polarized light, transmits only the modulated P-polarized light, guides the modulated P-polarized light to the projection lens, and forms an image on a screen. Further, Japanese Patent Application Laid-Open No. 11-2490
No. 76 discloses the use of PBS and DP to reduce incident light to PB.
Only the P-polarized light is transmitted to the light valve through the DP through the S-polarized light separation film, and the P-polarized light is modulated into the S-polarized light according to the image signal.
And a projection display device that transmits P-polarized light, reflects only modulated S-polarized light, guides the modulated S-polarized light to a projection lens, and forms an image on a screen.

[0003]

However, in the prior art, since an air gap is required between the PBS and the DP, each of them must be independently fixed to the housing of the display device. It was also necessary to improve the processing accuracy and assembly accuracy for this purpose. Also, if there is an air gap between the PBS and the DP, the position of each of the corresponding pixels on the plurality of light valves is likely to shift after being assembled to the device, and the color tone may change during use. Therefore, a first object of the present invention is to provide a projection device and a projection method that can accurately arrange a relationship between a plurality of LCDs (liquid crystal displays) and an optical system by fixing a PBS and a DP. A second object of the present invention is to fix a PBS and a DP, thereby eliminating positional displacement of each corresponding pixel on a plurality of light valves corresponding to each color after assembly and obtaining a high-purity color tone. An object of the present invention is to provide a projection device and a projection method.

[0004]

According to the first aspect of the present invention, the incident light is polarized (P-polarized light) having the same vibration direction as the incident light.
And a polarization beam splitter (PB) that separates and outputs polarized light (S-polarized light) having a vibration direction different from that of the P-polarized light by 90 degrees.
S), a dichroic prism (DP) for separating the separated P-polarized light or S-polarized light into light of two wavelength bands in a dichroic film, and a dichroic film of the DP based on an electric signal. Liquid crystal display (LCD) that reflects polarized light or separated light by rotating the polarization direction by about 90 degrees
Wherein the PBS and the DP
The first and second ports are provided by disposing the PBS and the DP so that no air layer is provided between the first and second ports.
Achieve the objectives.

According to a second aspect of the present invention, in the first aspect of the invention, the PBS and the DP are bonded with a transparent adhesive material having the same density as that of each of the glass materials, so that the first and the second layers are bonded. Achieve two objectives. According to a third aspect of the present invention, in the first or the second aspect of the present invention, the DP dichroic film is set at 30 degrees with respect to the main optical axis.
The first and second objects are achieved by setting and disposing each time. According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the DP dichroic film is disposed at an angle of 45 degrees with respect to the main optical axis, thereby providing the first and second DPs. Achieve the objectives.

According to the fifth aspect of the present invention, the polarization beam splitter (PBS) converts the incident light into polarized light (P-polarized light) having the same vibration direction as the incident light, and the P-polarized light has a vibration direction of 90 degrees.
A first procedure of separating and outputting polarized light (S-polarized light) having different degrees, and separating the P-polarized light or the S-polarized light output by the first procedure into light of two wavelength bands in a dichroic film. A second procedure, based on an electrical signal, a second display by a liquid crystal display (LCD).
A third procedure of maintaining the polarization direction of the light separated into the two wavelength bands by the above procedure, or rotating the polarization direction of the separated light by about 90 degrees to reflect the light, and the S-polarized light or the P-polarized light. When either polarized light is incident, the S-polarized light or the P-polarized light is guided to the DP, or when the random light is incident, the S-polarized light or the P-polarized light is incident.
A fourth procedure of arranging the PBS so that either the polarized light or the P-polarized light is guided to the DP, and rotating the desired polarized light at the other end of the DP by about 90 degrees to reflect and return the polarized light. A fifth procedure of disposing the LCD and a sixth procedure of disposing the PBS and the DP so that no air layer is provided between the PBS and the DP. The first and second objects are achieved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a diagram showing a configuration of a PBS prism and a DP of the projection display device according to the present embodiment. FIG. 1A shows the first
1 (b) is a diagram showing a conventional projection display device of the embodiment. As shown in FIG. 1B, an air gap 4 is provided at the boundary between the PBS prism and the DP of the conventional projection display device. In the PBS prism 1, the light incident from the X direction has a polarization direction of 90 degrees between the incident polarized light (hereinafter referred to as P polarized light) and the P polarized light.
The light is separated into differently polarized light (S-polarized light). Then, only the S-polarized light is reflected by the polarization separation film surface 5 and is guided to DP2. Here, if P-polarized light is mixed with the incident light, it is transmitted and removed. The boundary surface between the PBS prism 1 and DP2 in the present embodiment has a specific gravity almost equal to that of the glass material, and is fixed with an adhesive having a transmittance of about 100% as shown in FIG. 1A. (Refer to the bonding surface 3), the S-polarized light goes straight as it is.

On the dichroic film surface A, about 500 nm
Longer wavelengths are transmitted and shorter wavelengths are reflected at wavelengths near the boundary. The reflected light (that is, light in the blue (B) region) is emitted from DP2, and is modulated by a reflection-type LCD provided ahead of the DP2. That is, the reflective LCD converts the arriving S-polarized light into P-polarized light when the electric signal is on, and reflects the S-polarized light when it is off. Both the S-polarized light and the P-polarized light reverse the path through which they pass, and
To reach. Then, the light converted into the P-polarized light is transmitted and emitted in the Y direction. The light that has been converted into the S-polarized light without being converted is reflected and returns to the X direction where it first entered.

The long-wavelength S-polarized light transmitted through the dichroic film surface A is transmitted through the dichroic film surface B at a wavelength of about 600 nm, and long wavelengths are transmitted and short wavelengths are reflected. The reflected light (that is, light in the red (R) region) is emitted from DP2, and is modulated by a reflection-type LCD provided ahead of the DP2. That is, when the electric signal is on, the arriving S-polarized light is converted into P-polarized light and reflected, and when the electric signal is off, the S-polarized light is reflected as it is. Both the S-polarized light and the P-polarized light arrive at the polarization separation film surface 5 by taking back the path that has passed. Then, the light converted into the P-polarized light is transmitted and emitted in the Y direction. The light that has been converted into the S-polarized light without being converted is reflected and returns to the X direction where it first entered.

S-polarized light having a wavelength transmitted through the dichroic film surface A and the dichroic film surface B (that is, light in the green (G) region) is emitted from DP2 and is modulated by a reflection type LCD provided ahead of the DP2. Is done. That is, when the electric signal is on, the arriving S-polarized light is converted into P-polarized light and reflected, and when the electric signal is off, the S-polarized light is reflected as it is. Both the S-polarized light and the P-polarized light arrive at the polarization separation film surface 5 by taking back the path that has passed. Then, the light converted into the P-polarized light is transmitted and emitted in the Y direction. The light that has been converted into the S-polarized light without being converted is reflected and returns to the X direction where it first entered. A projection lens (not shown) is provided in the Y direction.
, And the RGB (red, green, blue) P-polarized light is synthesized, and an image can be formed on a screen installed in front of it.

Next, a case where illumination light is incident from the Y direction will be described. Light incident from the Y direction is transmitted through the polarization separation film surface 5 only for P-polarized light and is guided toward DP2. Here, if S-polarized light is mixed, it is reflected and removed.
The boundary surface between the PBS prism 1 and DP2 in the present embodiment has a specific gravity almost equal to that of the glass material, and is fixed with an adhesive having a transmittance of about 100% as shown in FIG. 1A. (Refer to the bonding surface 3), the P-polarized light travels straight as it is. On the dichroic film surface A, a long wavelength is transmitted and a short wavelength is reflected at a wavelength around 500 nm as a boundary. This reflected light (ie blue (B)
The light of the region) is emitted from DP2 and is modulated by a reflection type LCD provided in front thereof. That is, the reflection type LC
D converts the arriving P-polarized light into S-polarized light when the electric signal is on, and reflects the P-polarized light as it is when the electric signal is off. This P-polarized light and S-polarized light are both
The path that has passed through is reversed and reaches the polarization separation film surface 5. Then, the light converted into the S-polarized light is reflected and emitted in the X direction. Light that has been converted to P-polarized light without conversion is
The transmitted light returns to the Y direction where the light first entered.

A long wavelength S-polarized light transmitted through the dichroic film surface A is transmitted at a wavelength of about 600 nm at the dichroic film surface B, and a long wavelength is transmitted and a short wavelength is reflected. The reflected light (that is, light in the red (R) region) is emitted from DP2, and is modulated by a reflection-type LCD provided ahead of the DP2. That is, when the electric signal is on, the arriving P-polarized light is converted into S-polarized light and reflected, and when the electric signal is off, the P-polarized light is reflected as it is. Both the P-polarized light and the S-polarized light arrive at the polarization separation film surface 5 by reversing the path that has passed. Then, the light converted into the S-polarized light is reflected and emitted in the X direction. The light, which is not converted and remains as P-polarized light, is transmitted and returns to the Y direction where it first entered.

The P-polarized light having the wavelength transmitted through the dichroic film surface A and the dichroic film surface B (that is, light in the green (G) region) is emitted from DP2 and is modulated by a reflection type LCD provided in front thereof. Is done. That is, when the electric signal is on, the arriving P-polarized light is converted into S-polarized light and reflected, and when the electric signal is off, the P-polarized light is reflected as it is. Both the P-polarized light and the S-polarized light arrive at the polarization separation film surface 5 by reversing the path that has passed. Then, the light converted into S-polarized light is reflected and emitted in the X direction. The light, which is not converted and remains as P-polarized light, is transmitted and returns to the Y direction where it first entered. A projection lens (not shown) is provided in the X direction, and the RGB S-polarized lights modulated by the respective reflective LCDs are combined, and an image is formed on a screen provided thereabove. You can do it. As described above, in the present embodiment, since the PBS prism 1 and the DP 2 can be integrally functioned by being accurately bonded, the RGB colors can be matched in pixel units, and the color reproducibility can be improved. Can be maintained.

FIG. 2 is a diagram showing the configuration of the PBS prism and DP of the projection display apparatus according to the present embodiment when the incident light is of two or three colors. FIG. 2A is a diagram illustrating a case where incident light is of two colors. The function of the projection display apparatus according to the present embodiment is the same regardless of whether the incident light is of two colors or three colors. When used for data display, two colors are often sufficient. In this case, the wavelength separation of the dichroic film surface is about 500 to 600 n.
It suffices if it is between m.

FIG. 2B is a diagram showing a case where incident light is of three colors. When random irradiation light is incident from the Y direction, the light is separated into S-polarized light and P-polarized light on the polarization separation film surface 5. Here, for example, the wavelength separation at the dichroic film surface 6 in the S-polarized light direction is about 600 nm, and the wavelength separation at the dichroic film in the P-polarized light direction is about 500 nm. Approximately 500nm before G1-LCD using S polarization side
Provide a blue cut filter that absorbs the following short wavelengths,
Before the G2-LCD using the P-polarized light side, a red cut filter for absorbing a long wavelength of about 600 nm or more is provided. And a projection lens (not shown) in the X direction;
A screen is provided at the end of the projection lens so that a desired image can be formed. It should be noted that when random irradiation light is incident from the X direction and used, the relationship is in contrast to the case where random irradiation light is incident from the Y direction. As shown in FIG. 2, the characteristics of the polarization separation film, in particular, P
It is possible to reinforce the fact that the polarized light has many ripples and high angle dependency as a transmission characteristic of polarized light, and a high-quality image can be obtained.

FIG. 3 is a diagram showing a case where the projector is used as a projector. Here, as an example, an embodiment is shown in which incident light of P-polarized light is changed to S-polarized light by an ON signal in an LCD and projected on a screen surface. FIG. 4 is a diagram showing a modified example when used as a projector.
Here, as an example, an embodiment is shown in which incident light of S-polarized light is changed to P-polarized light by an ON signal in an LCD and projected on a screen surface. Details of the polarization conversion function will be described later.

Next, the polarization conversion function inserted between the lamps 10 and 11 and the projection display apparatus of the present embodiment will be described. FIG. 5 is a diagram showing a concept of an illumination system for explaining a polarization conversion function. FIG. 5 shows an embodiment in which random light generated by a lamp is converted into only S-polarized light or only P-polarized light and irradiated onto the LCD. LL1 and LL2 are at right angles, the reflector is a spheroidal mirror, and the second
Uses orthogonal lenticulars for fly eyes. Further, the polarization conversion function is performed by a polarization alignment prism array, and a system in which a PBS and a prism for separating into S-polarized light and P-polarized light are arranged in an array is used. Thereby, the polarization conversion efficiency can be improved. By using such an illumination system, light generated from the lamp can be effectively used.

FIG. 6 is a diagram showing an embodiment in which the positional relationship between the film surfaces of PBS and DP is rotated by 90 degrees. As shown in FIG. 6, the rotation of 90 degrees can reduce the occurrence of color unevenness. FIG. 7 shows that the DP film surface is
It is a figure showing an embodiment when it is set to 5 degrees. Thus, the relationship between the plurality of LCDs and the optical system can be arranged with high precision, so that the positional deviation of each corresponding pixel can be reduced and the occurrence of color unevenness can be reduced. Also, when the DP film surface is set at 30 degrees with respect to the main optical axis, the occurrence of color unevenness can be similarly reduced.

[0019]

According to the first aspect of the present invention, PBS and DP are used.
Since the PBS and DP are installed and projected so that no air layer is provided between them, the relationship between a plurality of LCDs and the optical system can be accurately arranged, and each corresponding pixel on a plurality of light valves corresponding to each color , The color tone of high purity can be obtained, the occurrence of the positional shift after assembling can be prevented, and the change of the color tone during use can be reduced. According to the second aspect of the present invention, since a transparent adhesive having the same density as that of each glass material is used to bond between the PBS and the DP, it is possible to prevent the occurrence of displacement after assembling, and to improve the color tone during use. Changes can be reduced. According to the third aspect of the present invention, since the DP dichroic film is set at an angle of 30 degrees with respect to the main optical axis, a higher purity color tone can be obtained. According to the fourth aspect of the present invention, since the DP dichroic film is arranged at an angle of 45 degrees with respect to the main optical axis, a higher purity color tone can be obtained.

According to the fifth aspect of the present invention, since the PBS and the DP are set and projected so that no air layer is provided between the PBS and the DP, the relationship between the plurality of LCDs and the optical system can be accurately arranged. Eliminates misalignment of each corresponding pixel on multiple light valves corresponding to each color, provides high-purity color tone, prevents misregistration even after assembly, and prevents color tone change during use. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a PBS prism and a DP of a projection display apparatus according to the present embodiment.

FIG. 2 is a diagram illustrating a configuration of a PBS prism and a DP of a projection display device according to the present embodiment when incident light is two colors or three colors.

FIG. 3 is a diagram showing a case where the projector is used as a projector.

FIG. 4 is a diagram showing a modified example when used as a projector.

FIG. 5 is a diagram showing a concept of an illumination system for explaining a polarization conversion function.

FIG. 6 is a diagram showing an embodiment in which the positional relationship between the film surfaces of PBS and DP is rotated by 90 degrees.

FIG. 7 is a diagram showing an embodiment in which the DP film surface is set at 45 degrees with respect to the main optical axis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PBS (polarization beam splitter) prism 2 DP (dichroic prism) 3 Adhesion surface 4 Air gap 5 Polarization separation film surface

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/13357 G03B 21/00 E 5C060 G03B 21/00 33/12 33/12 33/12 H04N 9/31 C H04N 9 / 31 G02F 1/1335 530 (72) Inventor Kazunari Miyagaki 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 2H042 CA01 CA06 CA08 CA10 CA14 CA16 CA17 2H049 BA05 BA42 BB61 BC14 BC22 2H088 EA15 EA16 HA13 HA20 MA05 MA20 2H091 FA05X FA10X FA14Z FA26X FA41X FD24 LA03 LA11 LA15 2H099 AA12 BA09 CA02 DA05 5C060 BA03 BA08 BC05 EA00 GB02 GB06 HC00 HC24

Claims (5)

[Claims] 1. A polarization beam splitter (PBS) for separating incident light into polarized light (P-polarized light) having the same vibration direction as the incident light and polarized light (S-polarized light) having a vibration direction different from the P-polarized light by 90 degrees and outputting the separated light. ) And a dichroic prism (DP) that separates the separated P-polarized light or S-polarized light into light of two wavelength bands in a dichroic film.
And a liquid crystal display (LCD) that reflects the light separated by the dichroic film of the DP or the separated light by rotating the polarization direction by about 90 degrees based on an electric signal. In the apparatus, the PBS and the DP are installed such that no air layer is provided between the PBS and the DP. 2. The projection apparatus according to claim 1, wherein said PBS and said DP are bonded with a transparent adhesive having the same density as each glass material. 3. The projection device according to claim 1, wherein the dichroic film of the DP is set at 30 degrees with respect to a main optical axis. 4. The projection device according to claim 1, wherein the dichroic film of the DP is set at 45 degrees with respect to a main optical axis. 5. A polarization beam splitter (PBS) for converting incident light into polarized light (P-polarized light) having the same vibration direction as the incident light,
Polarized light (S-polarized light) whose vibration direction differs from this P-polarized light by 90 degrees
A second procedure of separating the P-polarized light or the S-polarized light output by the first procedure into light of two wavelength bands in a dichroic film; and Based on the signal, the polarization direction of the light separated into the two wavelength bands in the second procedure is maintained by the liquid crystal display (LCD), or the polarization direction of the separated light is rotated by about 90 degrees. A third procedure for reflection, and when either the S-polarized light or the P-polarized light enters, the incident S-polarized light or P-polarized light
A fourth procedure of arranging the PBS so that one of the S-polarized light and the P-polarized light is guided to the DP when guided to P or when the random light is incident; A fifth procedure of arranging the LCD so that the desired polarized light is rotated by about 90 degrees and reflected and returned at the other end of the DP, and the air layer is not provided between the PBS and the DP. 6. A projection method, comprising: a PBS and a sixth procedure for arranging the DP.