KR100716959B1 - Light source assembly and projection display device using the same - Google Patents

Abstract

And a light source and an incident surface to which light generated and emitted from the light source is incident, wherein the first polarized light propagates and the second polarized light is fed back toward the upper incident surface to change the polarized light. Disclosed is a light source assembly and a projection display device including the alignment unit and a first reflecting member for reflecting light from the polarization alignment unit through the incident surface to face the incident surface.

The disclosed light source assembly can convert incident light into a single polarized light irrespective of wavelength, and thus has a high polarization efficiency, thereby minimizing light loss. In addition, the disclosed light source assembly has a structure that maintains the size of the beam incident from the light source side as it is, it is possible to reduce the light loss even when employed in the projection display device. Thus, a projection display device employing the disclosed light source assembly can achieve high brightness.

Description

Light source assembly and projection display apparatus employing the same

1 is a view schematically showing a conventional projection display device;

2 is a schematic view of a projection display device employing a light source assembly according to the present invention;

3 to 9 schematically show a light source assembly according to the first to seventh embodiments of the present invention.

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

50 ... light source assembly 51 ... light source

53,102,104,112,142,144 ... reflective member 55 ... fly eye lens array

57.Condensing Lens 70 ... Image Generation / Projection Unit

101,103,111,121,123,141 ... polarization beam splitter

101a, 103a, 111a, 121a, 123a, 141a ... Divided surface 105,107,145 ... 1/4 wave plate

135 ... 1/2 Wavelength In ...

The present invention relates to a light source assembly and a projection display device employing the same, and more particularly, a light source assembly capable of improving light utilization efficiency by improving a structure of a polarization alignment unit that converts light emitted from a light source into a single polarized light. And it relates to a projection display device that can achieve high brightness by employing this.

In general, a projection display device is a device for projecting an image formed on a display element onto a screen by using light emitted from a light source. Projection display devices include a front projection type and a rear projection type depending on the direction in which the image is projected on the screen. In addition, the projection display apparatus has a reflection type and a transmission type according to the type of display element. A projection display device having a transmissive or reflective liquid crystal display element as a display element has a light source assembly for outputting light of a single polarization.

Referring to FIG. 1, a conventional projection display apparatus includes a light source assembly 10 for outputting light having a single polarization, and a fly-eye lens array 35 for mixing uniform light by injecting light incident from the light source assembly 10. And an image generation / projection unit 40 for projecting an image formed on the display element using the condensing lens 37 for focusing the incident light and the irradiated single polarized light.

The light source assembly 10 includes a light source 11 and a polarization alignment unit that converts light of any polarization emitted from the light source 11, that is, natural light into light of a single polarization. The light source 11 includes a lamp. One side of the lamp is provided with a reflector to reflect the light irradiated from the lamp. The reflector guides the light emitted from the lamp to travel in one direction.

The polarization alignment unit includes a polarization beam splitter 20 and a pair of half wave plates 31 and 33. The polarization beam splitter 20 divides the first and second split surfaces 21 and 23 which transmit light of P-polarized light and reflect light of S-polarized light away from the optical axis among the light incident from the light source 11. ) And the first and second reflecting surfaces 25 reflecting light of S-polarized light reflected and incident from the first and second split surfaces 21 and 23, respectively, and traveling in parallel with the light of P-polarized light. (27) is provided. The 1/2 wavelength plates 31 and 33 are provided on the traveling path of the light of the S-polarized light reflected from the first and second reflecting surfaces 25 and 27 to rotate the light of the S-polarized light by 90 degrees. The light is converted into P-polarized light. Thus, the polarization alignment unit makes light of a predetermined wavelength emitted from the light source 11 into light of a single polarization.

The light of the single polarized light emitted from the polarization alignment unit as described above is irradiated to the image generation / projection unit 40 via the fly's eye lens array 35, the condensing lens 37, or the like, and the image generation / projection unit ( 40 projects an image formed on the display element on the screen (not shown) using the irradiated light.

By the way, the light emitted from the light source 11 is, for example, white light in the wavelength range of 400nm to 600nm. The half-wave plates 31 and 33 have a phase retardation difference between the light of the polarization component along the fast axis and the light of the polarization component along the slow axis only for light having a specific wavelength λ within the wavelength range. It satisfies the condition of / 2. Therefore, the 1/2 wavelength plates 31 and 33 rotate the polarization direction at an angle other than 90 degrees with respect to light outside the specific wavelength λ, so that the light emitted from the polarization alignment unit The light is mixed. In view of this, in the conventional projection display apparatus, the polarization alignment unit and the image generation / projection unit 40, as shown in FIG. 1, so that only the light of P polarization is input to the image generation / projection unit 40. The polarizer 39 which transmits only the light of P polarization is further provided.

As described above, in the polarization alignment unit, not only P polarized light but also S polarized light is emitted, and the emitted S polarized light cannot be used for image projection. Thus, a predetermined amount of light loss occurs.

Meanwhile, since the polarization beam splitter 20 of the polarization alignment unit illustrated in FIG. 1 has a structure in which a beam of light incident from the light source 11 is enlarged and output, the cross-sectional area of the beam emitted from the polarization alignment unit is closer to the light source 11. The cross-sectional area of the beam inputted to the polarization alignment unit is greatly increased, thereby increasing the difference between the area of the display element and the cross-sectional area of the beam emitted from the polarization alignment unit. As the cross-sectional area difference increases as described above, a condensing lens 37 having a small F-number (a ratio of the lens size and the focal length of the lens, the shorter the focal length of the lens and the larger the lens size, the smaller the F-number) should be used. The angle of light incident on the display element is increased, resulting in a large light loss. This is because light having an incident angle of approximately 12 degrees or more among the light incident on the display element cannot be used to project an image.

The present invention has been made to solve the above disadvantages, and can be changed into a single polarized light irrespective of the wavelength without expanding the size of the beam incident from the light source side, so that the polarization alignment unit high light utilization efficiency It is an object of the present invention to provide a projection display device that can achieve a high brightness by employing the improved light source assembly and the structure of the.

A light source assembly according to the present invention for achieving the above object, the light source; And an incident surface to which light generated and emitted from the light source is incident, wherein the first polarized light propagates and the second polarized light is fed back toward the incident surface to change the polarized light. An alignment unit; And a first reflecting member reflecting light from the polarization alignment unit through the incident surface to face the incident surface.

The polarization alignment unit may include: a polarization beam splitting device having first and second split surfaces for transmitting or reflecting incident light according to a polarization component and reflecting light having a predetermined polarization in a direction away from each other; Second and third reflecting members reflecting the light of the second polarized light transmitted or reflected from the first and second dividing surfaces to feed back toward the incident surface; And a wavelength plate positioned between the first reflecting member and the polarization beam splitting device to change the polarization of light passing therethrough.

The polarization alignment unit includes: a polarization beam splitting device having a split surface for transmitting or reflecting incident light according to a polarization component; A second reflecting member reflecting the light of the second polarized light transmitted or reflected by the dividing surface and feeding it back toward the incident surface; And a wavelength plate positioned between the first reflecting member and the polarization beam splitting device to change polarization of light passing therethrough.

The polarization alignment unit includes a polarization beam splitting device having first and second dividing surfaces which transmit light of a first polarization of the incident light and reflect light of the second polarization toward each other and feed back toward the incident surface; ; And a wavelength plate positioned between the first reflecting member and the polarization beam splitting device to change the polarization of light passing therethrough.

In the polarization alignment unit as described above, the wavelength plate may be formed to be located over the entire area of the incident surface, or may be a quarter-wave plate formed to be positioned over the half of the incident surface.

In the polarization alignment unit as described above, the wave plate may be a half wave plate formed to be positioned over a half region of the incident surface.

The polarization alignment unit comprises: a polarization beam splitting device having a dividing surface for advancing to a half region about an axis transverse to an optical axis and transmitting or reflecting light incident on the incident surface according to a polarization component; A second reflecting member reflecting the light of the second polarized light transmitted or reflected by the dividing surface and feeding it back toward the incident surface; A third reflecting member reflecting light traveling toward the other half region with respect to the axis crossing the optical axis toward the first reflecting member; And a wavelength plate positioned between the polarization beam splitting device and the first reflecting member to change the polarization of the incident light.

Here, the wave plate is preferably a quarter wave plate.

Projection display apparatus according to the present invention for achieving the above object, and a light source for generating and emitting light; And an incident surface to which light generated and emitted from the light source is incident, wherein the first polarized light propagates and the second polarized light is fed back toward the incident surface to change the polarized light. An alignment unit; A first reflection member formed to surround one side of the light source and reflecting the light incident from the light source and the light from the polarization alignment unit toward the incident surface; And an image generation / projection unit projecting an image formed on the display element toward the screen by using the light of the first polarized light output from the polarization alignment unit.

Hereinafter, a light source assembly and a projection display device employing the same according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2, the projection display apparatus according to the present invention includes a light source assembly 50 for emitting a single polarized light and an image generation / projection for projecting an image formed on a display element using the single polarized light toward a screen. And a projection unit 70. Then, between the light source assembly 50 and the image generation / projection unit 70, a light mixing device, for example, a fly's eye lens array 55 for condensing the incident light, for mixing the incident light to make uniform light. 57 is disposed.

The light source assembly 50 according to the embodiments of the present invention includes a light source 51 that generates and emits light, and a polarization alignment unit and a reflective member that converts and outputs the light emitted from the light source 51 into a single polarized light. (53).

The light source 51 includes lamps such as xenon and halogen. In the lamp type light source 51, for example, white light in a wavelength range of 400 nm to 600 nm is emitted radially, so that the reflecting member 53 is formed to surround one side of the light source 51, so that the light source 51 and the It is preferable that the reflecting mirror is configured to reflect light incident from the polarization alignment unit toward the polarization alignment unit. At this time, the reflecting member 53 is preferably a parabolic mirror whose position of the light source 51 is one focal point, and the light emitted from the light source 51 and reflected by the reflecting member 53 becomes parallel light. . The light source 51 may include a light emitting diode that emits white light of high power.

The polarization alignment unit has an incident surface In to which light generated and emitted from the light source 51 is incident. In this polarization alignment unit, light of the first polarized light, for example, P-polarized light (polarized light in a direction parallel to the surface) of the light incident on the incidence plane In is advanced, and light of the second polarized light, for example, Light of polarized light (polarized light in a direction perpendicular to the surface) is fed back toward the incident surface In to change the polarized light.

The projection display device according to the present invention may employ one of the light source assemblies 50 according to embodiments of the present invention. 2 shows an example employing a light source assembly 50 according to the first embodiment of the present invention.

Referring to FIG. 3, the polarization alignment unit of the light source assembly 50 according to the first embodiment of the present invention transmits or reflects light incident on the incident surface In according to a polarization component and transmits light having a predetermined polarization to each other. A polarization beam splitting device having first and second splitting surfaces 101a and 103a for reflecting in a distant direction, and for example, S-polarized light reflected from the first and second splitting surfaces 101a and 103a. Change the polarization of the light positioned between the first and second reflecting members 102 and 104 and the reflecting member 53 and the incident surface In, respectively, which are reflected and fed back toward the incident surface In. And wave plates 105 and 107 to be used.

The polarization beam splitting device may include a first polarization beam splitter 101 having a first split surface 101a and a second polarization beam splitter 103 having a second split surface 103a as shown in FIG. 3. . Alternatively, the polarization beam splitting device may have a structure in which the first and second polarization beam splitters 101 and 103 are integrated so that two right triangular prisms and one isosceles triangular prism are combined. The first and second divided surfaces 101a and 103a and the first and second reflecting members 102 and 104 are disposed symmetrically with respect to the optical axis. The first and second reflecting members 102 and 104 may be coated on the surfaces of the first and second polarization beam splitters 101 and 103. 3 shows an example in which the first and second reflecting members 102 and 104 are formed to feed back the light reflected from the first and second dividing surfaces 101a and 103a toward the incident surface In. . The first and second reflecting members 102 and 104 may be provided to feed back the light transmitted through the first and second split surfaces 101a and 103a toward the incident surface In. At this time, the optical system structures of the fly-eye lens array 55, the condensing lens 57, and the image generation / projection unit 70 as shown in FIG. 2 are appropriately modified.

The wavelength plates 105 and 107 are composed of first and second wavelength plates 105 and 107 formed to be positioned over half of the incident surface In, respectively, and are emitted to the incident surface In to reflect the reflections. The polarization of the light propagating toward the member 53 is changed, and the polarization of the light reflected by the reflecting member 53 and propagating toward the incident surface In is changed again. The first and second wave plates 105 and 107 are formed of light of a polarization component parallel to its fast axis and polarization component parallel to its slow axis with respect to light having a specific wavelength λ emitted from the light source 51. It is preferable that it is a quarter-wave plate which satisfies the condition that the phase retardation difference between the light is? / 4. In this case, the first and second wavelength plates 105 and 107 may be arranged in a direction in which their rapid axes are the same or perpendicular to each other. In this case, even when the fast axes of the first and second wavelength plates 105 and 107 are arranged in the same direction, a desired polarization change may be caused, so that the wavelength plates 105 and 107 have an incident surface In. It may be a single wave plate formed to be located over the entire area.

Hereinafter, the optical structure of FIG. 3 will be described in which the light of the single polarized light is emitted from the light source assembly 50 according to the first embodiment of the present invention regardless of the wavelength.

The light source 51 emits light of arbitrary polarization, that is, natural light. The light L1 emitted from the light source 51 directly enters through the first wavelength plate 105 or enters the first split surface 101a of the first polarization beam splitter 101, or the reflective member 53. After reflected from the light incident through the first wavelength plate 105. Similarly, the light L2 emitted from the light source 51 directly enters through the second wavelength plate 107 or is incident on the second split surface 103a of the light source second polarization beam splitter 103. It is reflected by the member 102 and then enters through the second wavelength plate 107. The light L1 (L2) incident on the first and second polarization beam splitters 101 and 103 after being emitted from the light source 51 is light in which P-polarized light and S-polarized light are mixed.

The first and second wavelength plates 105 and 107 are arranged in the same direction with their fast axes so that light of S-polarized and P-polarized light having a specific wavelength is first circularly polarized, for example, right circularly polarized light and orthogonal thereto. For example, the first and second planes 101a and 103a of the first and second polarization beam splitters 101 and 103 are allowed to transmit P-polarized light, If the polarized light is reflected, the P-polarized light of the light L1 incident to the first polarization beam splitter 101 via the first wavelength plate 105 passes through the first division surface 101a to generate an image. Proceed to the projection unit 70. S-polarized light of the incident light L1 is reflected by the first split surface 101a and directed toward the first reflecting member 102. The light is sequentially reflected from the first reflecting member 102 and the first split surface 101a and then fed back toward the incident surface In. Of the feedback S-polarized light, light having a specific wavelength that satisfies the condition that the first wavelength plate 105 becomes a quarter-wave plate passes through the first wavelength plate 105 to become first circularly polarized light. The light of the first circularly polarized light becomes the second circularly polarized light at the first reflection member 102 and the first circularly polarized light at the second reflection, and is directed toward the second wavelength plate 107. The light of the first circularly polarized light becomes P-polarized light while passing through the second wavelength plates 105 and 107, and the light of the P-polarized light is divided into the second dividing surface 103a of the second polarization beam splitter 103. The light passes through the image generating / projection unit 70. P-polarized light of the light L2 incident to the second polarization beam splitter 103 via the second wavelength plate 107 passes through the second division surface 103a to pass through the image generation / projection unit 70. On the other hand, the light of S polarized light becomes P polarized light through a path opposite to the above, passes through the first dividing surface 101a of the first polarization beam splitter 101 and proceeds to the image generating / projection unit 70.

Light having a wavelength deviating from a specific wavelength that does not satisfy the condition that the first and second wavelength plates 105 and 107 become a quarter wave plate passes through the first and second wavelength plates 105 and 107. But it is not a full circular polarization. Accordingly, when light of a wavelength deviating from a specific wavelength is reincident to the first or second polarization beam splitter 101 or 103 through the above circulation and / or reverse circulation process, the light cannot be completely converted into P polarization and S It contains a polarizing component. However, the light of this S-polarized component (shown in dashed lines in FIG. 3) is completely converted into P-polarized light while repeating the above-described cyclic and / or cyclic processes.

Therefore, the light source assembly 50 according to the first embodiment of the present invention emits light of a single polarization irrespective of the wavelength.

Referring to FIG. 4, the polarization alignment unit of the light source assembly 50 according to the second embodiment of the present invention includes a polarization beam splitting device having one split surface 111a corresponding to the entire area of the incident surface In. That is, the polarizing beam splitter 111, the wave plate 105, and 107 and the reflecting member 112 are included. The reflective member 112 reflects the light transmitted or reflected from the dividing surface 111a and feeds it toward the incident surface In. The reflective member 112 is preferably formed on the surface of the polarizing beam splitter 111. Here, the wave plate 105 and 107 may be a single wave plate, and the same reference numerals as in FIG. 3 denote the same members. In the light source assembly 50 according to the second embodiment of the present invention as shown in FIG. 4, the polarization beam splitter 111 is first used via the first wavelength plate 105 of the light emitted from the light source 51. The principle that the light L2 incident to the polarization beam splitter 111 for the first time via the light L1 incident to the second wavelength plate 107 is output as a single polarized light and is output with reference to FIG. 3. It is simply inferred from the operation description of the light source assembly 50 according to the first embodiment of the present invention described. Therefore, the repetitive description is omitted.

Referring to FIG. 5, the polarization alignment unit of the light source assembly 50 according to the third embodiment of the present invention transmits, for example, P-polarized light and S-polarized light among the light incident through the incident surface In. Is provided with a polarization beam splitting device having first and second splitting surfaces 121a and 123a which are reflected toward each other and fed back toward the incident surface In. The polarization beam splitting device may include a first polarization beam splitter 121 having a first split surface 121a and a second polarization beam splitter 123 having a second split surface 123a. Alternatively, the polarization beam splitting device may have a structure in which the first and second polarization beam splitters are integrated to combine two right-angled triangular prisms and one isosceles triangular prism. The polarization alignment unit according to the present embodiment does not require the first and second reflecting members 122 and 124 as compared with the first embodiment of the present invention shown in FIG. In FIG. 5, the same reference numerals as used in FIG. 3 denote the same members having substantially the same functions. In FIG. 5, the wave plates 105 and 107 may be a single wave plate as described above.

If the first and second split surfaces 101a and 103a of the first and second polarization beam splitters 101 and 103 transmit light of P polarization and reflect light of S polarization, the light source 51 P-polarized light of the light L1 incident to the first polarization beam splitter 121 for the first time through the first wavelength plate 105 after being emitted passes through the first split surface 121a to generate / project an image. Proceeding to the unit 70, the light of S polarization is sequentially reflected from the first and second divided surfaces 121a and 123a and then fed back to the incident surface In. Similarly, P-polarized light of the light L2 incident on the second polarization beam splitter 123 for the first time via the second wavelength plate 107 after being emitted from the light source 51 is the second split surface 123a. The light is transmitted through the image generating / projecting unit 70, and the light of the S-polarized light is sequentially reflected from the second and first split surfaces 123a and 121a and then fed back to the incident surface In.

Of the S-polarized light fed back to the incident surface In, light having a specific wavelength satisfying the condition that the first and second wavelength plates 105 and 107 become a quarter-wave plate is the second and first wave plate. It becomes P-polarized light while passing through (107) 105 (105) or vice versa, and the light of this P-polarized light is the 1st or 2nd dividing surface 121a of the 1st or 2nd polarizing beam splitter 121 (123). It passes through 123a and proceeds to the image generation / projection unit 70.

Light having a wavelength deviating from a specific wavelength that does not satisfy the condition that the first and second wavelength plates 105 and 107 become a quarter wave plate is subjected to the first and second cycles through the above-described circulation and / or reverse circulation process. When re-injected into the bipolar beam splitters 121 and 123, the polarization beam splitter 121 does not completely convert to P-polarized light and contains S-polarized light. However, the light of this S-polarized component is completely converted into P-polarized light while repeating the above-described circulation and / or reverse circulation process.

Therefore, the light source assembly 50 according to the third embodiment of the present invention can emit light of a single polarization for all wavelengths as in the first embodiment of the present invention.

6 to 8 show a fourth to sixth embodiments of the light source assembly 50 having a structure corresponding to each of the first to third embodiments of the present invention. 6 to 8, the light source assembly 50 according to the fourth to sixth embodiments of the present invention is formed to be positioned over a half region of the incident surface In, and is half with respect to an axis crossing the optical axis. The wavelength plate 135 which changes the polarization of the light which advances to an area | region is provided. In this case, the wave plate 135 is preferably a half wave plate 135 with respect to a specific wavelength of light emitted from the light source 51. 6 to 8, the same reference numerals as those in the foregoing embodiments indicate the same members.

Hereinafter, when the wavelength plate 135 is provided with the 1/2 wavelength plate, the light of the single polarized light is emitted to the light of all wavelengths in the light source assembly 50 according to the fourth to sixth embodiments of the present invention. The fourth embodiment of the present invention shown in Fig. 6 will be described by way of example.

Referring to FIG. 6, the first and second dividing surfaces 101a and 103a of the first and second polarization beam splitters 101 and 103 transmit light of P polarization and reflect light of S polarization. If the wavelength plate 135 is positioned on the side of the first polarization beam splitter 101, the light incident on the first polarization beam splitter 101 for the first time through the wavelength plate 135 after being emitted from the light source 51 ( The light of P polarization of L1 passes through the first division surface 101a and proceeds to the image generation / projection unit 70, and the light of S polarization is reflected on the first division surface 101a to reflect the first reflection member ( 102). The light is sequentially reflected from the first reflecting member 102 and the first split surface 101a and then fed back to the incident surface In. Of the light fed back to the incident surface In, light having a specific wavelength that satisfies the condition that the wavelength plate 135 becomes a half-wave plate becomes P polarized light while passing through the wavelength plate 135. The P-polarized light is reflected twice by the reflecting member 53 and then enters the second polarization beam splitter 103 through the incident surface In, and passes through the second split surface 103a to generate / project the image. Toward the unit 70. Similarly, P-polarized light of the light L2 incident to the second polarization beam splitter 103 after being emitted from the light source 51 passes through the second split surface 103a to generate an image / projection unit 70. ), The light of S polarized light is reflected by the second dividing surface 103a and directed toward the second reflecting member 104. This light is sequentially reflected from the second reflecting member 104 and the second dividing surface 103a and then fed back to the incident surface In. The light fed back to the incident surface In is reflected twice by the reflecting member 53 and then incident on the wave plate 135. Of light incident on the wave plate 135, light having a specific wavelength satisfying the condition that the wave plate 135 becomes a half wave plate becomes P polarized light while passing through the wave plate 135. The light of the P-polarized light is incident on the first polarization beam splitter 101 through the incident surface In, passes through the first split surface 101a, and proceeds to the image generation / projection unit 70.

The light having a wavelength deviating from a specific wavelength that does not satisfy the condition that the wavelength plate 135 becomes the 1/2 wavelength plate 135 is subjected to the first or second polarization beam splitter 101 through the cyclic or reverse circulation process as described above. When reincident at) 103, it does not completely convert to P-polarized light and contains light of S-polarized component. However, the light of this S-polarized component (indicated by the dashed lines) is completely converted into P-polarized light while repeating the above-described cyclic or reverse circulation process. Therefore, the light source assembly 50 according to the fourth embodiment of the present invention shown in FIG. 6 emits light of a single polarization for all wavelengths, and has a high polarization efficiency. Similarly, the light source assembly 50 according to the fifth and sixth embodiments of the present invention shown in FIGS. 7 and 8 also emits light of a single polarization for all wavelengths, and has a high polarization efficiency.

The polarization alignment unit of the light source assembly 50 according to the first to sixth embodiments has the incident surface In and the divided surface formed over the entire area of the light beam emitted from the light source 51 and incident on the polarization alignment unit. A polarization beam splitting device having a structure is provided.

Alternatively, as shown in FIG. 9, the polarization alignment unit of the light source assembly 50 according to the present invention has an incident surface (In) in which light propagating in a half region with respect to an axis crossing the optical axis is incident to the polarization beam splitting device. It may be provided with a single polarization beam splitter having a). Referring to FIG. 9, the polarization alignment unit of the light source assembly 50 according to the seventh embodiment of the present invention is divided into a half region to transmit or reflect light incident on the incident surface In according to a polarization component. A polarization beam splitter 141 having a surface 141a, a wavelength plate 135 positioned on the incident surface In side of the polarization beam splitter 141, and light transmitted or reflected by the division surface 141a. First reflecting member 122 for feeding back toward the incident surface In, and a second reflecting member reflecting light traveling toward the other half region with respect to the axis crossing the optical axis toward the reflecting member 53 ( 124). The polarization beam splitter 141 is a single polarization beam splitter having one division surface 141a. The wave plate 135 is preferably a quarter wave plate with respect to light having a specific wavelength emitted from the light source 51. The first reflective member 122 is preferably formed on the surface of the polarizing beam splitter 141.

The light source assembly 50 according to the seventh embodiment of the present invention configured as shown in FIG. 9 outputs light of a single polarization for all wavelengths by the following principle. Light emitted from the light source 51 and incident to the polarization beam splitter 141 for the first time via the wave plate 145 is mixed with light of P-polarized light and light of S-polarized light. Here, the light incident to the polarization beam splitter 141 for the first time is the light emitted from the light source 51 and directly incident, the light emitted from the light source 51 and reflected by the reflecting member 53, the light source ( And light incident on the reflective member 53, the second reflective member 144, and the second reflective member 144, and then reflected twice by the reflective member 53.

The dividing surface 141a of the polarization beam splitter 141 transmits light of P polarization and reflects light of S polarization, and the wave plate 145 orthogonally crosses light of S and P polarization of a specific wavelength. If it is provided to change the circularly polarized light, P-polarized light emitted from the light source 51 and incident on the polarization beam splitter 141 passes through the dividing surface 141a and proceeds to the image generating / projection unit 70. Then, the light of S polarization is reflected and directed toward the first reflecting member 142. The light of the S-polarized light is sequentially reflected from the first reflecting member 142 and the dividing surface 141a and then fed back to the incident surface In. This feedback light is converted into the light of the first circularly polarized light in the wave plate 145. The light of the first circularly polarized light is reflected by the reflection member 53 (twice reflection) and the second reflection member 144 and then reflected five times until the light is incident on the wavelength plate 145 through the reverse process. It becomes the second circularly polarized light and is reincident to the wave plate 145. The incident light is converted into P-polarized light while passing through the wave plate 145, and passes through the dividing surface 141a to proceed to the image generating / projection unit 70. For light having a wavelength that does not satisfy the condition that the wave plate 145 is a quarter wave plate 145, the light that is reincident to the polarization beam splitter 141 includes not only P polarized light but also S polarized light. However, by repeating the above cyclic process it can be changed to P polarization irrespective of the wavelength. Therefore, the light source assembly according to the seventh exemplary embodiment of the present invention as shown in FIG. 9 can emit light having a single polarization irrespective of the wavelength, thereby having high polarization efficiency and minimizing light loss.

Referring back to FIG. 2, the light of the single polarized light emitted from the light source assembly 50 according to one of the first to seventh embodiments of the present invention is mixed in the fly's eye lens array 55 to be uniform. The light is condensed by the condensing lens 57 and input to the image generation / projection unit 70.

At this time, since the light source assembly 50 according to the present invention emits light of a single polarization irrespective of the wavelength with high polarization efficiency, the projection display device employing the same does not require the conventional polarizer 39, so that the structure is simple. It has high light efficiency.

In addition, since the polarization alignment unit of the light source assembly 50 according to the present invention maintains the size of the light beam incident from the light source 51, the cross-sectional area of the beam emitted from the polarization alignment unit and the image generation / projection unit ( The area difference of the display element of 70 is smaller than that of the conventional, so that the condensing lens 57 having a relatively large F-number can be used. When the condensing lens 57 having a large F-number is used in this way, the angle of light incident on the display element is relatively smaller than in the prior art, so that the optical loss is greatly reduced in comparison with the conventional.

On the other hand, the image generation / projection unit 70 is, for example, a transmissive liquid crystal display device using a transmissive liquid crystal display device for forming an image and light of a single polarized light irradiated from the light source assembly 50, for example. And a projection lens for projecting an image formed on the screen. The image generation / projection unit having a structure for projecting images of three colors (for example, R, G, and B) independently formed on the screen includes three transmissive liquid crystal display elements, color separation devices, and dichroisms that form images of each color. And a beam splitter. The color separation device separates the white light incident from the light source assembly 50 into three colors of light and irradiates the light to each transmissive liquid crystal display device. The dichroic beam splitter collects the light of each color transmitted through the image formed in each liquid crystal display element in one optical path so as to be input to the projection lens. When a reflective liquid crystal display element is employed as the display element, the optical system structure is changed accordingly. As described above, the optical system structure of the image generation / projection unit for projecting an image of three colors (for example, R, G, and B) independently formed using a transmissive or reflective liquid crystal display element on a screen is well known.

In the above, an example in which the light source assembly according to the embodiments of the present invention is employed in the light source assembly 50 of the projection display apparatus has been described and illustrated. The light source assembly according to the embodiments of the present invention may be employed in any optical system that requires a single polarized light using a light source that emits light of arbitrary polarization, in addition to the projection display apparatus. In addition, the light source assembly according to the present invention can output a single polarized light irrespective of the wavelength even when the light emitted from the light source has a predetermined wavelength range, and thus is adopted in any optical system requiring a single polarized white light. Can be.

The light source assembly according to the present invention as described above can convert the incident light into a single polarized light irrespective of the wavelength, and thus has a high polarization efficiency, thereby minimizing light loss. In addition, the light source assembly according to the present invention has a structure that maintains the size of the beam incident from the light source side as it can reduce the light loss when employed in the projection display device. Therefore, the projection display device employing the light source assembly according to the present invention can achieve high brightness.

Claims (24)

A light source; And an incident surface to which light generated and emitted from the light source is incident, wherein the first polarized light propagates and the second polarized light is fed back toward the incident surface to change the polarized light. An alignment unit; And a first reflecting member reflecting light from the polarization alignment unit through the incident surface to face the incident surface. The method of claim 1, wherein the polarization alignment unit, A polarization beam splitting device having a dividing surface for transmitting or reflecting incident light according to a polarization component; A second reflecting member reflecting the light of the second polarized light transmitted or reflected by the dividing surface and feeding it back toward the incident surface; And a wave plate positioned between the first reflecting member and the polarization beam splitting device to change the polarization of light passing therethrough. The light source assembly of claim 2, wherein the second reflecting member is coated on a surface of the polarization beam splitting device. The method of claim 1, wherein the polarization alignment unit, A polarization beam splitting device having first and second dividing surfaces which transmit or reflect incident light according to a polarization component and reflect light of predetermined polarization in a direction away from each other; Second and third reflecting members reflecting the light of the second polarized light transmitted or reflected from the first and second dividing surfaces to feed back toward the incident surface; And a wave plate positioned between the first reflecting member and the polarization beam splitting device to change the polarization of light passing therethrough. The light source assembly of claim 4, wherein the second and third reflecting members are coated on a surface of the polarization beam splitting device. The method of claim 1, wherein the polarization alignment unit, A polarization beam splitting device having first and second dividing surfaces which transmit light of the first polarized light of the incident light and reflect light of the second polarized light toward each other and feed back toward the incident surface; And a wave plate positioned between the first reflecting member and the polarization beam splitting device to change the polarization of light passing therethrough. The light source assembly according to any one of claims 2 to 6, wherein the wave plate is a quarter wave plate formed to be positioned over the entire incident surface area. The wave plate of claim 2, wherein the wave plate comprises first and second wave plates formed so as to be respectively positioned over the half surface area of the incident surface. Light source assembly, characterized in that the quarter-wave plate. The light source assembly according to any one of claims 2 to 6, wherein the wave plate is a half wave plate formed to be positioned over a half region of the incident surface. The method of claim 1, wherein the polarization alignment unit, A polarization beam splitting device having a dividing surface for propagating or reflecting light incident on the incidence plane according to a polarization component by advancing to a half region with respect to an axis crossing the optical axis; A second reflecting member reflecting the light of the second polarized light transmitted or reflected by the dividing surface and feeding it back toward the incident surface; A third reflecting member reflecting light traveling toward the other half region with respect to the axis crossing the optical axis toward the first reflecting member; And a wave plate positioned between the polarization beam splitting device and the first reflecting member to change the polarization of the incident light. The light source assembly of claim 10, wherein the wave plate is a quarter wave plate. The light source assembly of any one of claims 1 to 6, 10 and 11, wherein the first reflecting member is a parabolic reflector formed to surround one side of the light source. A light source for generating and emitting light; And an incident surface to which light generated and emitted from the light source is incident, wherein the first polarized light propagates and the second polarized light is fed back toward the incident surface to change the polarized light. An alignment unit; A first reflection member formed to surround one side of the light source and reflecting the light incident from the light source and the light from the polarization alignment unit toward the incident surface; And an image generation / projection unit projecting an image formed on the display element toward the screen by using the light of the first polarized light output from the polarization alignment unit. The method of claim 13, wherein the polarization alignment unit, A polarization beam splitting device having a dividing surface for transmitting or reflecting incident light according to a polarization component; A second reflecting member reflecting the light of the second polarized light transmitted or reflected by the dividing surface and feeding it back toward the incident surface; And a wave plate positioned between the first reflecting member and the polarization beam splitting device to change the polarization of light passing therethrough. The projection display apparatus according to claim 14, wherein the second reflecting member is coated on a surface of the polarization beam splitting device. The method of claim 13, wherein the polarization alignment unit, A polarization beam splitting device having first and second dividing surfaces which transmit or reflect incident light according to a polarization component and reflect light of predetermined polarization in a direction away from each other; Second and third reflecting members reflecting the light of the second polarized light transmitted or reflected from the first and second dividing surfaces to feed back toward the incident surface; And a wave plate positioned between the first reflecting member and the polarization beam splitting device to change the polarization of light passing therethrough. 17. The projection display device of claim 16, wherein the second and third reflecting members are coated on a surface of the polarization beam splitting device. The method of claim 13, wherein the polarization alignment unit, A polarization beam splitting device having first and second dividing surfaces which transmit light of the first polarized light of the incident light and reflect light of the second polarized light toward each other and feed back toward the incident surface; And a wavelength plate positioned between the first reflecting member and the polarization beam splitting device to change the polarization of light passing therethrough. 19. The projection display device according to any one of claims 14 to 18, wherein the wave plate is a quarter wave plate formed to be positioned over the entire incident surface area. 19. The method according to any one of claims 14 to 18, wherein the wave plate comprises first and second wave plates formed so as to be respectively positioned over the half surface area of the incident surface. Projection display device, characterized in that the quarter-wave plate. 19. The projection display device according to any one of claims 14 to 18, wherein the wave plate is a half wave plate formed to be positioned over a half region of the incident surface. The method of claim 13, wherein the polarization alignment unit, A polarization beam splitting device having a dividing surface for propagating or reflecting light incident on the incidence plane according to a polarization component by advancing to a half region with respect to an axis crossing the optical axis; A second reflecting member reflecting the light of the second polarized light transmitted or reflected by the dividing surface and feeding it back toward the incident surface; A third reflecting member reflecting light traveling toward the other half region with respect to the axis crossing the optical axis toward the first reflecting member; And a wave plate positioned between the polarization beam splitting device and the first reflecting member to change the polarization of the incident light. 23. A projection display device according to claim 22, wherein the wavelength plate is a quarter wave plate. The projection display apparatus according to any one of claims 13 to 18, 22 and 23, wherein the first reflecting member is a parabolic reflector.

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