JPH05173020A - Polarized beam splitter - Google Patents

Abstract

PURPOSE:To produce a light and inexpensive polarized beam splitter by forming the 1st and 2nd prisms by plastic resin. CONSTITUTION:The 1st and 2nd plastic prisms 9, 10 to be rectangular prisms are produced by plastic resin and a polarizing glass plate 8 formed by holding a polarizing film 5 between the 1st and 2nd optical glass plates 6, 7 is held between the prisms 9, 10 so that the inclined faces of the prisms 9, 10 are abutted upon each other to form the polarized beam spritter 1 with an approximately cubic shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization beam splitter suitable for use in, for example, a liquid crystal projector device.

[0002]

2. Description of the Related Art Conventionally, for example, a transmissive liquid crystal panel for red (R) and green (G) by a video signal corresponding to a desired video.
Liquid crystal projector in which a transmission type liquid crystal panel for blue and a transmission type liquid crystal panel for blue (B) are respectively driven, and the parallel light from the light source section is converted into image light by each of the transmission type liquid crystal panels and the image light is projected on a screen. The device is known.

In such a liquid crystal projector device, it is preferable to irradiate each of the transmissive liquid crystal panels with the S-wave polarization component of the parallel light from the light source section. A polarization beam splitter for separating the light into a wave polarization component is provided.

Here, the polarization beam splitter is formed by sandwiching a polarization film having polarization dependency such that the bottom surfaces of two right-angle prisms made of optical glass are butted against each other, and the butted shapes are obtained. Is a cube. The polarization film is adapted to reflect the S-wave polarization component and transmit the P-wave polarization component of the parallel light. The P-wave polarization component transmitted through the polarizing film is converted into an S-wave polarization component by the S-wave polarizing plate, and the transmission type liquid crystal panels are irradiated with the S-wave polarization component reflected by the polarizing film.

In addition to the polarizing beam splitter formed by sandwiching the polarizing film between the two right-angle prisms, a plate-type polarizing beam splitter is known. This plate-type polarization beam splitter is formed by sandwiching a polarizing film as described above between two plate-shaped optical glass plates. This plate type polarization beam splitter is also adapted to reflect the S-wave polarization component and transmit the P-wave polarization component of the parallel light as described above.

[0006]

However, the polarization beam splitter using the above two right-angle prisms, which is a conventional polarization beam splitter, has excellent characteristics, but an optical glass is used to form the right-angle prism. Is used,
It was heavy and expensive. Further, if the polarization beam splitter using the two right-angle prisms is to be provided in a large-sized liquid crystal projector device, the polarization beam splitter using the two right-angle prisms must also be increased in size. As described above, the polarization beam splitter using the two right-angle prisms is heavy and expensive,
When the size of the polarization beam splitter using the two right-angle prisms is increased, the size of the large-sized liquid crystal projector device also becomes heavy and expensive.

The polarization beam splitter using the two optical glass plates is lighter than the polarization beam splitter using the two right-angle prisms, but the polarization beam splitter using the two right-angle prisms is used. In order to perform polarization separation efficiently over a wide wavelength range of visible light, which is inferior in characteristics to the splitter, the incident angle of the parallel light is increased, for example, to about 70 degrees. There was a need. For this reason, the space of the optical system for polarization-separating the parallel light with the polarization beam splitter using the two optical glass plates becomes large, and a small liquid crystal is used with the polarization beam splitter using the two optical glass plates. When trying to manufacture a projector device, it was difficult to design the optical system.

The present invention has been made in view of the above problems, and is a polarizing beam splitter that can be manufactured at a low weight and at a low cost, and can efficiently perform polarized light separation without increasing the incident angle. For the purpose of providing.

[0009]

A polarization beam splitter according to the present invention reflects an S-wave polarization component and transmits a P-wave polarization component of light incident through an incident surface, and transmits the P-wave polarization component through each emission surface. A polarizing glass plate provided with a polarizing film that reflects the S-wave polarization component of the incident light and transmits the P-wave polarization component of the incident light; an incident surface of the light; There is a first plastic prism forming an emission surface of the S-wave polarization component reflected by the polarizing glass plate and a second plastic prism forming an emission surface of the P-wave polarization component transmitted through the polarizing glass plate. The polarizing glass plate is sandwiched between the first plastic prism and the second plastic prism to solve the above problems.

Further, the polarization beam splitter according to the present invention reflects the S-wave polarization component and transmits the P-wave polarization component of the light incident through the incident surface, and emits the light through each emission surface. A polarizing beam splitter, the polarizing film reflecting the S-wave polarized component and transmitting the P-wave polarized component of the incident light, and the S-wave polarized component reflected by the incident surface of the light and the polarizing film. Of the first plastic prism forming the exit surface of P and the P transmitted through the polarizing film.
A second plastic prism forming an exit surface of the wave polarization component, wherein the polarizing film is sandwiched between the first plastic prism and the second plastic prism, and at least the first plastic prism The above-mentioned problem is solved by providing an inclination on the incident surface of the light so as to have a predetermined incident angle.

[0011]

In the polarizing beam splitter according to the present invention, a polarizing glass plate provided with a polarizing film that reflects the S-wave polarization component and transmits the P-wave polarization component of the incident light is provided on the incident surface of the light and the polarizing glass plate. A first plastic prism that forms an emission surface of the S-wave polarization component reflected by the polarizing glass plate and a second plastic prism that forms the emission surface of the P-wave polarization component that passes through the polarizing glass plate are sandwiched between the first plastic prism and the second plastic prism. As a result, since the first plastic prism and the second plastic prism formed of plastic resin are used, the polarization beam splitter can be manufactured at a lighter weight and a lower cost than using optical glass.

Further, in the polarization beam splitter according to the present invention, a polarizing film that reflects the S-wave polarization component and transmits the P-wave polarization component of the incident light is tilted so that the light has a predetermined incident angle. And a second plastic forming an emission surface of the S-wave polarization component reflected by the polarization film and an emission surface of the P-wave polarization component transmitted through the polarization film. With the configuration sandwiched by the prisms, since the plastic resin is used for everything except the polarizing film, the polarizing beam splitter can be manufactured at a lighter weight and at a lower cost.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the polarization beam splitter according to the present invention will be described below with reference to the drawings.
First, in FIG. 1, the polarization beam splitter 1 of the first embodiment according to the present invention reflects the S-wave polarization component of the light incident through the incident surface 2 and emits it from the S-wave emission surface 3. , A P-wave polarization component that transmits the P-wave polarization component and exits from the P-wave emission face 4, and a polarization film 5 that reflects the S-wave polarization component and transmits the P-wave polarization component of the light incident from the incident face 2. The first optical glass plate 6 and the second optical glass plate 7
A polarizing glass plate 8 sandwiched between and a first plastic prism 9 forming the incident surface 2 and the S-wave emission surface 3.
And a second plastic prism 10 forming the P-wave emission surface 4.

In the first plastic prism 9, the incident surface 2 and the S wave emission surface 3 are at right angles, and the incident surface 2
And a so-called right-angled prism having an inclined surface of 45 degrees with respect to the S-wave emission surface 3. Further, the second plastic prism 10 is also a similar rectangular prism.
The inclined surfaces of the first and second plastic prisms 9 and 10 are abutted against each other, and the polarizing glass plate 8 is sandwiched between the abutting portions of the inclined surfaces, so that the cube-shaped polarized beam. A splitter 1 is formed.

Therefore, the polarizing glass plate 8 is sandwiched between the plastic prisms 9 and 10 so that the incident angle of light is 45 degrees. The first and second plastic prisms 9 and 10 are made of a plastic resin such as polymethylmethacrylate (PMMA), polycarbonate, polystyrene, etc., and have a refractive index of light equal to that of the first and second plastic prisms. The refractive index of light of the optical glass plates 6 and 7 is almost the same.

Next, when the polarization beam splitter 1 having such a structure is provided in the liquid crystal projector device as shown in FIG. 2, the operation of the liquid crystal projector device and the characteristics of the polarization beam splitter 1 will be described. To do. First, in this liquid crystal projector device, the halogen lamp 21 is driven to be turned on by the power supply 20. This allows
The halogen lamp 21 emits light, and the reflector 22 emits parallel light. Infrared components of the parallel light are removed by passing through the infrared cut filter 23,
It is incident on the polarization beam splitter 1.

The parallel light incident on the polarization beam splitter 1 is adapted to be incident perpendicularly on the incident surface 2 of the polarization beam splitter 1, and includes the first plastic prism 9 and the first plastic prism 9. The light is incident on the polarizing film 5 via the optical glass plate 6.

The polarizing film 5 reflects the S-wave polarization component and transmits the P-wave polarization component as described above. Therefore, of the parallel light incident on the polarizing film 5, the S-wave polarization component is reflected and the P-wave polarization component is transmitted. The S-wave polarization component reflected by the polarization film 5 is emitted from the S-wave emission surface 3 through the first optical glass plate 6 and the first plastic prism 9 in this order, and is emitted to the first dichroic mirror 24. It The P-wave polarization component transmitted through the polarization film 5 is emitted from the P-wave emission surface 4 via the second optical glass plate 7 and the second plastic prism 10 in this order and is applied to the first reflection mirror 25. It

The first reflection mirror 25 reflects the P-wave polarization component and irradiates it on the S-wave polarization plate 26. The S-wave polarization plate 26 forms an S-wave polarization component from the P-wave polarization component by subjecting the P-wave polarization component to S-wave polarization processing, and irradiates the first dichroic mirror 24 with this.

As described above, since the first and second plastic prisms 9 and 10 which are right-angled prisms are made of plastic resin, the polarization beam splitter 1 can be manufactured lightweight and at low cost. it can. Therefore, even if the polarization beam splitter 1 is increased in size to be provided in a large-sized liquid crystal projector device, it does not cost much, and since it is lightweight, it can contribute to weight reduction of the large-sized liquid crystal projector device.

Further, since the incident parallel light is incident on the polarizing glass plate 8 through the first plastic prism 9, the incident angle of the parallel light incident on the polarizing glass plate 8 is not increased. Also (in this case, for example, 45 degrees), it is possible to efficiently perform polarization separation over a wide wavelength range of visible light. Therefore, it is possible to reduce the space of the optical system that polarizes and separates the parallel light into the S-wave polarization component and the P-wave polarization component, and to simplify the design of the optical system. It can also contribute to miniaturization.

The first dichroic mirror 24 is
Of the S-wave polarization component directly radiated from the polarization beam splitter 1 and the S-wave polarization component from the S-wave polarization plate 26, the R component is transmitted and the G and B components are reflected.
The R component is reflected by the second reflection mirror 27 to be R
The transmissive liquid crystal panel 31R is irradiated, and the G component and the B component are irradiated on the second dichroic mirror 28.

The second dichroic mirror 28 is
The B component is reflected to illuminate the B transmissive liquid crystal panel 31B, and the G component is transmitted. The transmitted G component is sequentially reflected by the third reflection mirror 29 and the fourth reflection mirror 30, and is applied to the G transmissive liquid crystal panel 31G.

Transmissive liquid crystal panels 31R, 31 for each color
G and 31B are each driven by a video signal corresponding to a desired video. Therefore, the R component radiated on the transmissive liquid crystal panels 31R, 31G, and 31B for the respective colors,
The G component and B component are the image light for R, the image light for G, and B
Image light for use in illuminating the combined dichroic mirror 32.

The above dichroic mirror 32 for synthesis
The image light for R, the image light for G, and the image light for B which are respectively irradiated are combined to form image light, which is projected on the screen 34 via the projection lens 33. As a result, a desired image is projected on the screen 34.

Next, the polarization beam splitter 40 of the second embodiment according to the present invention, as shown in FIG. 3, is a polarization beam which reflects the S-wave polarization component of the incident light and transmits the P-wave polarization component. The film 41, the light incident surface 42, and the polarizing film 4
A first plastic prism 44 forming an emission surface (S-wave emission surface) 43 of the S-wave polarization component reflected by 1.
And a second plastic prism 46 that forms an emission surface (P-wave emission surface) 45 of the P-wave polarization component that has passed through the polarization film 41.

The above first and second plastic prisms 4
4, 46 are made of a plastic resin similarly to the first and second plastic prisms 9, 10 shown in FIG. In the first plastic prism 44, the angle of the incident surface 42 with respect to the S-wave emission surface 43 is 90 degrees or less, and the angle of the inclined surface with respect to the S-wave emission surface 43 is 45 degrees. The second plastic prism 46 is also formed to have the same shape as the first plastic prism 42.

The above first and second plastic prisms 4
The inclined surfaces of the four and the four are abutted with each other, and the polarizing beam splitter 40 is formed by sandwiching the polarizing film 41 in the abutting portion of the inclined surfaces. Therefore, the polarizing film 41 is sandwiched between the plastic prisms 44 and 46, so that the incident angle of light is 45 degrees.

The polarization beam splitter 40 according to the second embodiment is thus formed by only the first and second plastic prisms 44 and 46 and the polarization film 41, as shown in FIG. Optical glass plate (first, second
The optical glass plates 6, 7) are not used. For this reason,
Although it can be made cheaper and lighter than the polarization beam splitter 1 according to the first embodiment, there is a possibility that the incident angle of light may become narrow because the optical glass plate is not used.

In order to prevent this, the incident surface 42 is provided with an inclination so as to have a predetermined incident angle, and
The P-wave emission surface 45 is provided with an inclination so as to have a predetermined emission angle. The inclination of the P-wave emission surface 45 may be set arbitrarily, and the S-wave emission surface 4 may be provided.
3 may be provided with an inclination that provides a predetermined emission angle.

As described above, the polarization beam splitter 40 according to the second embodiment having such a structure is such that the incident angle is narrowed by providing the incident surface 42 with an inclination so as to have a predetermined incident angle. Therefore, in the same manner as the polarization beam splitter according to the first embodiment shown in FIG.
It is possible to efficiently perform polarization separation over a wide wavelength range of visible light without increasing the incident angle of the parallel light incident on the polarizing film 41.

Therefore, the space of the optical system for polarization-separating the parallel light into the S-wave polarization component and the P-wave polarization component can be reduced, the design of the optical system can be facilitated, and the liquid crystal projector can be designed. It can also contribute to downsizing of devices and the like. Further, since the first and second plastic prisms 44 and 46 are made of plastic resin, the polarization beam splitter 40 can be manufactured lightweight and at low cost.

Therefore, even if the polarization beam splitter 40 is enlarged to be installed in a large-sized liquid crystal projector device, it does not cost much, and since it is lightweight, it can contribute to the weight reduction of the large-sized liquid crystal projector device. ..

In the polarization beam splitter 1 according to the first embodiment described above, the polarizing glass 8 is sandwiched between the first and second plastic prisms 9 and 10 which are right angle prisms. For example, as shown in FIG. 4A, the polarizing glass 54 may be sandwiched between the first plastic prism 52 and the second plastic prism 53, each of which has the incident surface 51 inclined at a predetermined angle. Good.

In this case, the incident surface 5 is
The incident angle of the light incident from 1 becomes larger due to the inclination provided on the incident surface 51, and the first optical glass plate 5
5, the polarization beam splitter shown in FIG. 4A can further increase the incident angle of light as compared with the polarization beam splitter 1 according to the first embodiment, which is more efficient. Polarization separation can be performed.

The polarizing film does not necessarily have to be sandwiched between two optical glass plates, and only one optical glass plate 63 is provided on the side of the polarizing film 61 facing the incident surface 62 as shown in FIG. 4B. May be provided. Also in this case, FIG.
Similar to the polarization beam splitter shown in (a), the incident angle of the light incident from the incident surface 62 is increased by the inclination provided on the incident surface 62 and further increased by the optical glass plate 63. The polarization beam splitter shown in FIG. 4B can make the incident angle of light larger than that of the polarization beam splitter 1 according to the first embodiment, and can perform more efficient polarization separation. ..

Incidentally, without providing the optical glass plate 63, as shown by the dotted line in FIG.
The optical glass plate 64 can be provided only on the side facing the wave emission surface 64), but the optical glass plate is the optical glass plate described above in view of increasing the incident angle of light and performing efficient polarization separation. It is preferable to provide it on the side facing the incident surface 62 like 63.

[0038]

The polarizing beam splitter according to the present invention is
Of the incident light, a polarizing glass plate provided with a polarizing film that reflects the S-wave polarized component and transmits the P-wave polarized component is used as an S-wave polarized component of the incident surface of the light and the S-polarized component reflected by the polarizing glass plate. The first plastic prism that forms the emission surface and the second plastic prism that forms the emission surface of the P-wave polarization component that has passed through the polarizing glass plate are sandwiched between the first plastic prism and the first plastic prism. Since the plastic prism and the second plastic prism are used, the polarization beam splitter can be manufactured at a lighter weight and at a lower cost than using optical glass.

Therefore, when the polarizing beam splitter according to the present invention is provided in, for example, a large-sized liquid crystal projector device, the polarizing beam splitter can be manufactured at low cost, so that the cost of the large-sized liquid crystal projector device can be reduced. You can contribute.

Further, in the polarization beam splitter according to the present invention, the polarizing film that reflects the S-wave polarization component and transmits the P-wave polarization component of the incident light is tilted so that the light has a predetermined incident angle. And a second plastic forming an emission surface of the S-wave polarization component reflected by the polarization film and an emission surface of the P-wave polarization component transmitted through the polarization film. With the configuration sandwiched by the prisms, since the plastic resin is used for everything except the polarizing film, the polarizing beam splitter can be manufactured at a lighter weight and at a lower cost.

Therefore, when the polarizing beam splitter according to the present invention is provided in, for example, a large-sized liquid crystal projector device, the polarizing beam splitter can be manufactured at low cost, so that the cost of the large-sized liquid crystal projector device can be reduced. You can contribute. Further, since the first plastic prism is formed by using the plastic resin, the inclination provided on the light incident surface can be easily provided in manufacturing, and the incident angle of light can be increased to widen the light. It is possible to inexpensively provide a polarization beam splitter that efficiently separates polarized light over a range.

Further, since it is possible to easily provide the polarization beam splitter capable of increasing the incident angle of the light, it is possible to contribute to the reduction of the optical system of the liquid crystal projector device, and the liquid crystal. It is possible to contribute to downsizing of devices such as a projector device.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a configuration of a polarization beam splitter of a first embodiment according to the present invention.

FIG. 2 is a schematic diagram when the polarization beam splitter of the first embodiment is provided in a liquid crystal projector device.

FIG. 3 is a vertical sectional side view showing a configuration of a polarization beam splitter according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional side view showing a modified example of the polarization beam splitter according to the present invention.

[Explanation of symbols]

 2, 42 ..... Incident surface 3, 43 ..... S wave exit surface 4, 45 ..... P wave exit surface 5 .....・ Polarizing film 6 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ First optical glass plate 7 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Second optical glass plate 8 ・ ・ ・ ・ ・ ・ ・ ・ Polarizing glass Plate 9 ... First plastic prism 10 ... Second plastic prism

Claims (2)

[Claims] 1. A polarization beam splitter that reflects an S-wave polarization component, transmits a P-wave polarization component of light incident through an incident surface, and emits the P-wave polarized component through each emission surface. Of the incident light, a polarizing glass plate provided with a polarizing film that reflects the S-wave polarized component and transmits the P-wave polarized component, and the S-wave polarized component of the incident surface of the light and the S-polarized component reflected by the polarizing glass plate A first plastic prism forming an emission surface and a second plastic prism forming an emission surface of the P-wave polarization component transmitted through the polarizing glass plate are provided, and the first plastic prism and the second plastic prism are provided. A polarizing beam splitter, characterized in that the polarizing glass plate is sandwiched between plastic prisms. 2. A polarization beam splitter that reflects an S-wave polarization component and transmits a P-wave polarization component of light incident through an incidence surface and emits the light through each emission surface. A polarization film that reflects the S-wave polarization component of the incident light and transmits the P-wave polarization component, and a first film that forms an incident surface of the light and an emission surface of the S-wave polarization component reflected by the polarization film. It has a plastic prism and a second plastic prism that forms an exit surface of the P-wave polarization component that has passed through the polarizing film, and the polarizing film is sandwiched between the first plastic prism and the second plastic prism. At the same time, at least the light incident surface of the first plastic prism is provided with an inclination so as to have a predetermined incident angle.