KR100830473B1 - Wedge prism and lighting optical system comprising the same - Google Patents

Abstract

The present invention relates to a wedge prism and an illumination optical system including the same, wherein the wedge prism birefringes light incident by joining a first supervisor having a high refractive index and a small dispersion rate and a second refractor having a small refractive index and a high dispersion ratio, thereby prescribing a predetermined angle. Deflect to. The present invention including the wedge prism includes a light source for irradiating white light, an integrator into which the irradiated light is incident, a color wheel for selectively transmitting only a predetermined wavelength of light passing through the integrator, and condensing the transmitted light. In the first, second and third illumination lens, the panel through which the light passing through the illumination lens is input, the prism positioned between the third illumination lens and the panel to adjust the light path, and in the first and second illumination lens And a birefringent member using the wedge prism that refracts the collected light, corrects chromatic aberration, and transmits the chromatic aberration to the third illumination lens.

Lighting, optics, wedge prism, refraction, chromatic aberration

Description

Wedge prism and illumination optical system including the same {WEDGE PRISM AND LIGHTING OPTICAL SYSTEM COMPRISING THE SAME}

1 is a schematic configuration diagram showing a general illumination optical system.

2 is a view schematically showing the deflection of light in the reflection mirror.

3 is a schematic configuration diagram of an illumination optical system according to an embodiment of the present invention.

4 is a structural diagram of a general wedge prism.

5 is a structural diagram of a wedge prism according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

30: light source 31: reflector

32: lamp 34: color wheel

35a, 35b, 35c: illumination lens 36: birefringent member

37: Panel 38: Prism

51, 52: splicing wedge prism

The present invention relates to a wedge prism and an illumination optical system including the same, and more particularly, to a wedge prism capable of reducing chromatic aberration in an off-Axis optical system and an illumination optical system including the same.

Recently, as the size of TV increases, a projection system has been studied.

Micro Display Devices applied to existing Front Projection and Rear Projection are largely transmissive Liquid Crystal Display (LCD) panels, reflective LCD panels such as LCoS, and Digital Micro- There is a mirror device panel, and the optical system of the projection system is divided into single plate type, two plate type and three plate type according to how many display elements are used.

In general, transmissive LCDs allow the design of on-axis illumination systems, and reflective LCDs allow the design of off-axis illumination systems, but most illuminators use on-axis illumination systems. have.

However, a display element such as a DMD is an optical switch display element that structurally changes the inclination angle of the mirror to +10 to -10 degrees to change the reflection angle of the light into two modes, and whether the signal is input by the mechanical movement of the mirror. Because of this, we need to use an off-axis illumination system that illuminates with the appropriate angle of incidence.

In the case of an illumination system using such a DMD device, the illumination system using a mirror lens and the illumination method using a TIR prism are largely classified.

Referring to Figure 1, a general illumination optical system will be described.

FIG. 1 is a single-plate illumination optical system, in which one lamp 2 uses an ellipsoidal mirror 1 to condense the light of the lamp 2 and the collected light is an integrator 3 and a color wheel 14. The light is collected by the first illumination lens 15a and the second illumination lens 15b and is illuminated by the reflection mirror 16 which deflects the path of light. The reflecting mirror 16 reflects the light to the third illumination lens 15c by deflecting the light at a predetermined angle for the design of the off-Axis illumination system. The light illuminated by the third illumination lens 15c is incident on the prism 18 to be applied to the panel 17, and is primarily reflected on the surface of the prism 21 and is incident on the panel 19. Light emitted from the panel 19 passes through the prism 21 and is transmitted to the projection lens (not shown).

When the light emitted from the light source 10 arrives, the panel 17 outputs image information to be projected by an appropriate switching or reflection process, and the image information is imaged on the screen through the projection lens. Incident. The projection lens is reflected or refracted in any one of the up / down directions in which the projection lens is positioned to be incident.

FIG. 2 is a diagram schematically illustrating deflection of light using the reflection mirror 16 of FIG. 1, which deflects light at a predetermined angle to make an off-axis illumination system.

As shown in FIG. 2A, the reflection area (area) of the reflection mirror 16 is proportional to the amount of incident light, that is, the width d of the incident light. Therefore, as shown in FIG. 2B, in order to deflect the light by a predetermined angle θ to make an off-Axis illumination system, the area of the reflecting mirror 16 becomes larger because L ′ <L ″. As this area increases, there is a problem that the size of the entire illumination optical system must also increase.

In consideration of the size of the entire system, the light may be deflected using a prism or a lens instead of the reflective mirror 16. However, there is a problem in that chromatic aberration of the deflected light occurs using the prism or the lens.

Accordingly, an object of the present invention is to provide a wedge prism capable of reducing chromatic aberration when light is deflected, and an illumination optical system including the same.

Another object of the present invention is to provide a wedge prism capable of reducing the size of the illumination optical system and an illumination optical system including the same.

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The illumination optical system according to the present invention for achieving the above object is a light source for irradiating white light, an integrator to which the irradiated light is incident, a color wheel to selectively transmit only a predetermined wavelength of light passing through the integrator, the transmitted light First, second and third illumination lenses for condensing light, a panel through which light passing through the illumination lenses is input, a prism positioned between the third illumination lens and the panel to adjust an optical path, and the first and second illumination lenses It comprises a birefringent member for refracting the light collected at the and correcting the chromatic aberration and transmitting to the third illumination lens.

Wherein the birefringent member is a bonded wedge prism having different refractive indices and dispersion rates. In this case, the incident surface of the birefringent member may be a BK7 superstructure, and the exit surface of the birefringent member may be an SF3 superstructure.

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Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments with reference to the accompanying drawings.

Illumination optical system according to a preferred embodiment of the present invention is as follows.

First, the illumination optical system using the wedge prism according to the present invention denotes the same reference numeral for the same configuration as the above-described prior art.

3 is a schematic configuration diagram of an illumination optical system according to an embodiment of the present invention.

As shown in FIG. 3, a light source 30 irradiating white light, an integrator 33 to which the irradiated light is incident, and a color wheel 34 selectively transmitting only a predetermined wavelength of light passing through the integrator ), First, second and third illumination lenses 35a, 35b and 35c for condensing the transmitted light, and a panel 37 to which light passing through the illumination lenses 35a, 35b and 35c is input. A prism 38 positioned between the third illumination lens 35c and the panel to adjust an optical path, and a birefringent member which birefringes the light collected by the first and second illumination lenses to the third illumination lens ( 36).

The light source 30 includes a lamp 32 that emits white light and a reflector 31 that reflects the light emitted from the lamp and condenses the integrator 33.

The light emitted from the light source 30 passes through the integrator 33 and the light emitted from the light source 30 has uniform illuminance. In addition, it may be shaped into a desired shape while passing through the integrator 33.

The integrator 40 may be a rod-shaped rod lens or an optical tunnel made of a box-shaped mirror.

As such, the output light having uniform illuminance in the integrator 40 or shaped into a desired shape is separated into red (R) / green (G) / blue (B) light and then separated R / G / B. The color wheel 34 irradiating the light in a set and the light separated from the color wheel 34 are collected through the first and second illumination lenses 35a and 35b and pass through the illumination lenses 35a and 35b. One light is refracted by the wedge prism 36 at a predetermined angle and is incident on the third illumination lens 35c.

The color wheel 34 has a circular shape having an R / G / B color separation region, and rotates to separate white light having high luminance emitted from the light source 30 into R / G / B light. It is composed.

The birefringent member 36 maintains the shape of off-axis illumination optics and determines the path of light deflected at a predetermined angle. Further, by adding a function of diffusing light to the surface of the birefringent member 36 or adding a diffuser plate, more uniform illumination light can be obtained. In the embodiment of the present invention, the birefringent member 36 birefringes the light incident from the second illumination lens 35b at a predetermined angle using the bonding wedge prism 36 and deflects the light to the third illumination lens 35c. To pass.

Light passing through the third illumination lens 35c is incident on the prism 38 to be applied to the panel 37.

At this time, the prism 38 has a boundary surface, and the light transmitted from the third illumination lens 35c is first reflected by the surface of the prism 44 and is incident on the panel 37, but the panel 37 The light emitted from is refracted or reflected by the prism 38 and transmitted to the projection lens (not shown).

When the light emitted from the light source 30 arrives, the panel 37 outputs light having image information by appropriate switching or reflection, and the light having the image information is the prism 38. The image is imaged on the screen (not shown) through the projection lens (not shown) positioned in the direction of reflection or refraction at.

The prism 38 separates / combines the incident light according to the number of panels 37 and transmits the light carrying the image information to the projection lens according to the control of the panel 37. This prism 38 mainly uses a TIR prism or an X prism.

The panel 42 may be any one of a digital micromirror device (DMD), a liquid crystal on silicon (LCoS), and a liquid crystal device (LCD). Such a panel 37 may be referred to as a micro switching element.

The panel 37 may be divided into a single panel panel, a two panel panel, and a three panel panel according to the number of liquid crystal panels, and may be divided into a transmissive panel and a reflective panel according to a method of converting a light beam into image information.

In the above-described embodiment of the present invention, the birefringent member 36 is constructed by using the bonding wedge prism 36 as an example in the embodiment of the present invention, but the birefringent member 36 which deflects light at a predetermined angle is the bonding. Not only the wedge prism 36 but another birefringent member may be used, and the thing which joined the material which has birefringence on the transparent substrate can also be used.

Therefore, it is possible to use variously if the 1st superfine 36a which has a large refractive index and a small dispersion rate and the 2nd superfine 36b which has a small refractive index and a large dispersion rate are joined.

In this case, the first choji 36a has a refractive index of 1.7 or more and a dispersion rate of 24 or less, and the second choja 36b uses a refractive index of 1.5 or less and a dispersion rate of 72 or more. A BK7 ruler is used as the first ruler 36a, and an SF3 ruler is used as the second ruler 36b.

In the above-described illumination optical system, the optical component has a structure in which the intervals between the optical components are narrowly arranged. Therefore, in order to construct an off-Axis optical system, when deflecting the optical path at a predetermined angle in the illumination optical system using the birefringent member 36 at a predetermined angle, the system of the whole illumination optical system In addition to reducing the size, it is also possible to reduce the occurrence of chromatic aberration generated when deflecting light.

4 is a structural diagram of a general wedge prism 41.

As shown in FIG. 4, the light emitted from the parallel quadrangle rectangular structure in which one surface is vertical, the light incident surface is a vertical plane A, and the light is refracted and the light exit surface is an inclined surface B. Is deflected and deflected at a predetermined angle. In addition, contrary to the above-described structure, the incident surface may be inclined and the exiting surface may be vertical.

At this time, the light incident on one of the incident surface A or the emitting surface B is refracted. The refractive index is 1.51 to 1.52, and the refractive critical angle is 21 ° to 27 °. Therefore, the light incident on the wedge prism 41 is refracted within the aforementioned refractive index and critical angle range.

Typical materials of the wedge prism 41 include glass, polymethyl methacrylate, polystyrene, polycarbonate, polyvinyl chloride, methyl methacrylate / styrene copolymer. Most transparent materials such as polymers (methacrylate / styrene copolymer) (NAS), and styrene / acrylo nitrile.

However, as illustrated, the wedge prism 41 may be used to refract incident light so that a predetermined deflection angle θ may be suitably used. However, when the incident light is refracted and deflected, R, G, and B may be used. Chromatic aberration occurs in the color by color.

In terms of chromatic aberration, if you simply refract white light with a prism, you will see that the refracted light appears like a rainbow. This is a phenomenon in which white light passes through the glass and the light spreads due to different refractive indices of each color. The wedge prism also appears, and such chromatic aberration occurs.

Accordingly, the present invention proposes a deformed wedge prism capable of reducing the aforementioned chromatic aberration.

The structure of the deformed wedge prism will be described in detail below as a junction wedge prism in which two superatoms are joined.

5 is a structural diagram of bonding wedge prisms 51 and 52 according to an embodiment of the present invention.

As shown in FIG. 5A, a rectangular first element 51a and a rectangular second element 51b having one side vertical and the other side inclined are bonded to each other, and the incident light is refracted in the A plane. Is deflected at a predetermined angle θ through the joint surface, and is deflected at a predetermined angle θ 'through the birefringence process on the B surface.

As shown in FIG. 5B, the first and second rectangular magnets 52a, in which one side is vertical and the other is inclined, are bonded to each other. The incident light is refracted in the A plane. Is deflected at a predetermined angle θ through the joint surface, and is deflected at a predetermined angle θ 'through the birefringence process on the B surface.

In order to deflect the incident light through such a birefringence process, the above-described structure uses two refractive surfaces (A, B) to be refracted at the same time, thereby reducing the refractive burden on each of the refracting surfaces and causing chromatic aberration generated by refracting. The phenomenon can be reduced.

The first choirs 51a and 52a mainly use chords having a high refractive index and a low dispersion rate, specifically, a chord having a refractive index of 1.7 or more and a dispersion ratio of 24 or less.

The second chokers 52b and 52b mainly use a small one having a small refractive index and a large dispersion rate, and specifically, a second one having a refractive index of 1.5 or less and a dispersion ratio of 72 or more.

As a specific example, the first seconds 51a, 52a mainly use BK7, and the second seconds 52b, 52b mainly use SF3.

The bonding of the above-described elements may be a method of forming a thin film having birefringence on a transparent substrate by means of vapor deposition or the like, as well as mechanical bonding such as adhesion and compression.

Since the refractive indices and the critical angles of the refractive surfaces A and B are the same as those described in FIG. 4, the description thereof will be omitted.

The above embodiment is an example for describing the technical idea of the present invention in detail, and the present invention is not limited to the above embodiment, various modifications are possible, and various embodiments of the technical idea are all protected by the present invention. It belongs to the scope.

As described above, the wedge prism according to the present invention and the illumination optical system including the same may deflect the light at a predetermined angle while maintaining the shape of the off-Axis illumination optical system.

Therefore, compared with the illumination optical system using the reflection mirror, it is possible to configure a compact illumination optical system, and there is an effect that it is possible to reduce the chromatic aberration phenomenon generated when deflecting and deflecting light.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (8)

delete delete delete delete A light source for emitting white light; An integrator in which the irradiated light is incident; A color wheel for selectively transmitting only a predetermined wavelength of light passing through the integrator; First, second and third illumination lenses for condensing the transmitted light; A panel through which light passing through the illumination lenses is input; A prism positioned between the third illumination lens and the panel to adjust an optical path; And And a birefringent member that refracts the light collected by the first and second illumination lenses, corrects chromatic aberration, and transmits the birefringent member to the third illumination lens. The method of claim 5, wherein the birefringent member, An illumination optical system, characterized in that the bonding wedge prism is different in refractive index and dispersion. The method according to claim 5 or 6, The incidence surface of the birefringent member is a BK7 supermagnet, characterized in that the illumination optical system. The method according to claim 5 or 6, The emission surface of the said birefringent member is SF3 supermagnet, The illumination optical system characterized by the above-mentioned.

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