KR100416539B1 - Reflection-type projecting apparatus - Google Patents

Abstract

PURPOSE: A reflective project device is provided to comprise a wavelength plate and a compensator between a polarized beam splitter and an LCD element, and to form thickness of a liquid crystal layer at a predetermined rate, thereby realizing almost perfect black/white as increasing contrast. CONSTITUTION: A light source(10) generates/projects a light. The first and second dichroic mirrors(41,45) transmit and reflect the incident light according to wavelength areas by being disposed on optical paths. The first, second and third image generators(50,60,70) generate images by color. A dichroic beam splitter(80) enables the light incident from the first, second and third image generators(50,60,70) to be emitted toward one direction. A projection lens unit(90) expansively projects the light incident from the dichroic beam splitter(80).

Description

Reflection-type projecting apparatus

The present invention relates to a reflective project apparatus, and more particularly, to a reflective project apparatus having an optical arrangement in which the optical axes of the illumination optical system and the projection optical system coincide.

In general, a project apparatus is an apparatus for providing an image by projecting an image generated by the image generating means onto a screen using a separate light source. This project apparatus is classified into a transmission type and a reflection type according to the shape of the image generating means described above.

Such a project apparatus can be designed as a non-axis optical system in which the optical axes of the illumination optical system and the projection optical system do not coincide, or an optical axis optical system in which the optical axes coincide. In practice, in the non-optical system, the design of the projection lens is difficult.

Further, in the case of the project apparatus employing the liquid crystal display element as the image generating means, the liquid crystal display element is driven by alternating current to maintain the durability of the liquid crystal display element. This makes it difficult to implement full black / white mode.

The present invention has been made in view of the above, and an object thereof is to provide an optical axis optical system in which the optical axes of the illumination optical system and the projection optical system coincide, and a reflection type project device having improved black / white mode characteristics.

1 is a view schematically showing an optical arrangement of a reflective project apparatus according to a first embodiment of the present invention;

2A, 3A, 4A, and 5A are diagrams illustrating modes of directors of a compensator and a liquid crystal display, and FIGS. 2B, 3B, 4B, and 5B are FIGS. 2A, 3A, 4A, and 5A, respectively. In the mode of, the polarization change process in each image generating unit is shown.

6 is a schematic view showing an optical arrangement of a reflective project apparatus according to a second embodiment of the present invention;

7 is an enlarged view of the polarization converter of FIG. 6,

8 schematically illustrates another embodiment of the polarization converter of FIG. 6.

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

10 ... Light 41,45 ... First and second dichroic mirrors

50,60,70 ... first, second and third image generating unit

51, 61, 71, 210 ... Polarized beam splitters 53, 63, 73 ...

55,65,75 ... compensator 57,67,77 ... liquid crystal display element

80 ... Dichroic beam splitters 83a, 83b ... First and second mirror

90 ... Projection lens unit 100 ... Polarization transducer

101 ... microlens array 110 ... beam separation member

111,113 1st and 2nd mirror surface 120,230 Half-wave plate

211,212 ... first and second light 220 ... reflector

Reflective project device according to the present invention for achieving the above object and a light source for generating and projecting light; A first dichroic mirror disposed on an optical path for transmitting and reflecting incident light according to a wavelength region to separate the first color light and the second and third color light; A second dichroic mirror disposed on an optical path and configured to transmit and reflect second and third color light via the first dichroic mirror; A polarization beam splitter for converting the advancing path of incident light by transmitting or reflecting the incident first, second or third color light according to the polarization, and an image for each color from the light incident through the polarization beam splitter A liquid crystal display device for generating and reflecting a light, a wavelength plate disposed on an optical path between the polarizing beam splitter and the liquid crystal display device to change the polarization of incident light, and an optical path between the polarizing beam splitter and the liquid crystal display device. First, second and third image generating units including a compensator for generating an image for each color; A dichroic beam splitter having first and second mirror surfaces selectively transmitting or reflecting light according to a wavelength such that light incident through the first, second and third image generating units is emitted in one direction; And a projection lens unit configured to enlarge and project the light incident from the dichroic beam splitter toward the screen.

Here, each of the liquid crystal display elements is preferably a ferroelectric liquid crystal display element.

In addition, each compensator includes a liquid crystal layer having substantially the same thickness as the corresponding liquid crystal display elements, and the thickness of the liquid crystal layer of the image generating unit for generating red, green, and blue images, respectively, is approximately 1.36: 1: 0.84. It is preferable that the ratio is made.

According to another embodiment of the present invention, it is preferable that a polarization converter for converting incident light into light of one polarization on the optical path between the light source and the first dichroic mirror.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing an optical arrangement of a reflective project apparatus according to a first embodiment of the present invention.

Referring to the drawings, the reflective project apparatus according to the first embodiment of the present invention includes a light source 10 for generating and projecting light, and a first and second light beams disposed on an optical path to transmit and reflect incident light according to the wavelength region thereof. Second dichroic mirrors 41 and 45, first, second and third image generating units 50 and 60 and 70 for generating images for each color, and the first, second and third ones. A dichroic beam splitter 80 for causing light incident from the image generating units 50, 60, 70 to exit in one direction, and a projection lens unit 90 for magnifying and projecting light incident from the dichroic beam splitter 80. It is configured to include).

The light source 10 includes a lamp 11 for generating light, and a reflector 13 for reflecting the light emitted from the lamp 11 and guiding a progress path thereof. The reflector 13 is an ellipsoidal mirror with the position of the lamp 11 as one focal point, and the point where the light is focused as another focal point, or the lamp 11 with the position of the lamp 11 as one focal point. It may be a parabolic mirror emitted from the light reflected by the reflector 13 to be parallel light.

On the optical path between the light source 10 and the first dichroic mirror 41 is further provided with a light mixing means 20 to diverge / converge or diffuse the light incident from the light source 10 side to be uniform light desirable. As shown in the light mixing means 20, the scrambler 21 and the focusing lens 23 may be adopted to diffuse the incident light into uniform light. The scrambler 21 is a rectangular parallelepiped glass having an entrance face and an exit face perpendicular to the optical path. In the exit surface 21a of the scrambler 21, the aspect ratio thereof is proportional to the aspect ratio of the liquid crystal display elements 57, 67 and 77 which will be described later. Thus, when the scrambler 21 is employ | adopted, it is preferable that the said reflecting mirror 13 is an elliptical mirror. Meanwhile, instead of the scrambler 21, it is also possible to have a pair of fly-eye lenses (not shown) disposed adjacent to each other. The focusing lens 23 is disposed on an optical path between the scrambler 21 and the first dichroic mirror 41 to focus incident light.

On the other hand, on the optical path between the focusing lens 23 and the first dichroic mirror 41 is preferably further provided with a collimating lens 24 for converting the focused light incident from the focusing lens 23 side to parallel light. Do.

The first dichroic mirror 41 transmits and reflects incident light according to its wavelength region to separate the first and second color light and the third color light. For example, the first dichroic mirror 41 transmits a first color light and a second color light, for example, red (R) and green light (G), and reflects a third color light, for example, blue (B) light. The first and second color light transmitted through the first dichroic mirror 41 are reflected by the reflecting mirror 44 and incident on the second dichroic mirrors 45 and 230. The second dichroic mirror 45 transmits, for example, first color light of the incident light and reflects the second color light.

The light transmitted through the second dichroic mirror 45 is incident on the first image generating unit 50, and the light reflected by the second dichroic mirror 45 is incident on the second image generating unit 60. do. In addition, the light reflected by the first dichroic mirror 41 is reflected by the reflecting mirrors 42 and 43 to convert the path and enter the third image generating unit 70.

The dichroic beam splitter 80 has three incident surfaces 81a, 81b, 81c and one exit surface 81d. Each of the three incident surfaces 81a, 81b, and 81c has light incident through the first, second, and third image generation units 50, 60, and 70 being the one emission surface 81d. The traveling path of the incident light is converted so as to face. To this end, the dichroic beam splitter 80 has first and second mirror surfaces 83a and 83b for selectively transmitting or reflecting light depending on the wavelength. The first mirror surface 83a is coated to transmit and reflect along the wavelength region, thereby reflecting light incident from the first image generating unit 50, and the second and third image generating units 60 and 70. The light incident on the) side is transmitted. The second mirror surface 83b is coated so as to transmit and reflect according to the wavelength region so that light incident from the first and second image generating units 50 and 60 is transmitted, and the third image generating unit 70 is transmitted. Reflects the light incident on the side). The dichroic beam splitter 80 as described above emits light incident from each of the three incident surfaces 81a, 8b, and 81c through the one emitting surface 81d.

The projection lens unit 90 is disposed between the dichroic beam splitter 80 and a screen (not shown) to enlarge and project the light incident from the dichroic beam splitter 80 toward the screen.

In the present embodiment, the first image generating unit 50 includes a first polarization beam splitter 51 for converting a traveling path of incident light, a first liquid crystal display element 57 for generating and reflecting an image, and the first image generating unit 50. A first wavelength plate 53 arranged on an optical path between the first polarization beam sputterer 51 and the first liquid crystal display element 57 to change the polarization of the incident light; and the first wavelength plate 53 and the first wavelength plate 53. And a first compensator 55 disposed on the optical path between the first liquid crystal display elements 57 to correct the color of the image generated by the first liquid crystal display element 57.

The first polarization beam splitter 51 transmits or reflects the incident first color light according to its polarization. The first liquid crystal display device 57 preferably has a two-dimensional array structure and is a reflective ferroelectric liquid crystal display device (FLCD) driven in alternating current. It is preferable that the first wavelength plate 53 is a quarter wave plate with respect to the first color light. The first compensator 55 includes a liquid crystal layer having a thickness substantially the same as that of the liquid crystal layer of the first liquid crystal display element 57, and the liquid crystal layer is similar to the first liquid crystal display element 57. It is preferably filled with.

Light of one polarized light transmitted through the first polarization beam splitter 51 is incident on the first liquid crystal display device 57 via the first wavelength plate 53 and the first compensator 55. The light reflected from the first liquid crystal display device 57 is incident on the first polarization beam splitter 51 via the first compensator 55 and the first wavelength plate 53, and only light having a different polarization is Reflected by the first polarizing beam splitter 51 is incident on the dichroic beam splitter 80.

The second image generating unit 60 includes a second polarization beam splitter 61, a second wavelength plate 63, a second compensator 65, and a second that are sequentially disposed similarly to the first image generating unit 50. The liquid crystal display element 67 is included. The third image generating unit 70, like the first image generating unit 50, has a third polarization beam splitter 71, a third wavelength plate 73, a third compensator 75 and a third liquid crystal display device. (77).

Each of the second and third polarization beam splitters 61 and 71 transmits or reflects incident second and third color light according to the polarization thereof. The second and third liquid crystal display elements 67 and 77 are preferably reflective ferroelectric liquid crystal display elements similar to the first liquid crystal display element 57. Like the first wavelength plate 53, the second and third wavelength plates 63 and 73 may be quarter wave plates for the second and third color light, respectively. Each of the liquid crystal layers 65 and 75 has the same thickness as that of the first compensator 55 and the liquid crystal layer of the second and third liquid crystal display elements 67 and 77, respectively. As with the second and third liquid crystal display elements 67 and 77, is preferably filled with a ferroelectric liquid crystal.

The compensators 55, 65, 75 and the liquid crystal display element 57 for correcting each color image in the first, second and third image generating sections 50, 60, 70 as described above. The thicknesses of the liquid crystal layers of (67) and (77) are respectively provided in the same manner.

Further, in the present embodiment, the thicknesses of the liquid crystal layers of the first, second, and third image generating units 50, 60, 70, which generate R, G, and B images, respectively, i.e., each image generating unit The sum of the liquid crystal layers of each of the compensators 55, 65, 75 and the liquid crystal display elements 57, 67, 77 at 50, 60, 70 is approximately 1.36: 1: 0.84. It is preferable. At this time, via the compensators 55, 65, 75 and the liquid crystal display elements 57, 67, 77, that is, the first, second, and third image generating units 50, 60, 70, respectively. The phase delay amount of each color light is kept constant. In this case, the contrast of the reflective project device according to the present invention can be maximized, and a nearly perfect black / white mode can be realized. Here, the ratio may be changed according to the characteristics of the lamp 11, that is, the emission wavelength characteristics, it is preferably optimized according to the characteristics of the lamp 11 is employed.

When the compensators 55, 65, 75 and the liquid crystal display elements 57, 67, 77 of each of the image generating units 50, 60, 70 are provided as described above, each compensator 55 65 and 75, and the liquid crystal display elements 57, 67 and 77, whose directors form an angle of approximately 90 ^ o`, + 45 ^ o`, or -45 ^ o` with each other. Black or white can be implemented for the four modes. 2A through 5B illustrate polarizations of the image generating units 50, 60, and 70 according to the modes of the compensators 55, 65, 75, and the liquid crystal display devices 57, 67, and 77. Shows the change and status of the projected image on the screen.

The compensators 55, 65, 75, and liquid crystal display elements 57, 67, and 77 have modes of compensators 55, 65, 75, and liquid crystal display elements 57, 67, and 77. ) And the first and the second mode (Figs. 2a and 3a) arranged so that the direction of each other to form 90 ^ o`, and the third and fourth modes arranged to form + 45 ^ o` and -45 ^ o` with each other 4A and 5A.

For example, the polarization beam splitters 51, 61, 71 transmit light of x-ray polarization, and the fast axes of the wave plates 53, 63, 73 are -45 degrees with respect to the x-axis. Let's say it's placed in the direction. In the first mode, as shown in FIG. 2A, the directors of the compensators 55, 65, and 75 are arranged in the x-direction, and the directors of the liquid crystal display elements 57, 67, and 77 are arranged in the y-direction. 2B, the light passing through the polarization beam splitters 51, 61, 71 and passing through the wavelength plates 53, 63, 73 becomes light of right circularly polarized light. When the light passes through the compensators 55, 65 and 75, it becomes linearly polarized light in the -45 degree direction with respect to the x-axis, and is incident and reflected by the liquid crystal display elements 57, 67 and 77 and emitted. The polarization changes by 90 degrees, resulting in linear polarization in the +45 degree direction. This linearly polarized light becomes circularly polarized light via the compensators 55, 65 and 75, and becomes x-ray polarized light via the wave plates 53, 63 and 73. Therefore, all of the light is reflected by the polarization beam splitters 51, 61, 71 and is incident on the dichroic beam splitter 80. Therefore, the image generated by the first, second and third image generating units 50, 60 and 70 and transmitted to the screen becomes white.

Similarly, in the second mode as shown in FIG. 3A, the light passing through each of the image generating units 50, 60, and 70 passes through a polarization change as shown in FIG. 3B, and thus an image projected on the screen. Becomes white.

Further, in the third and fourth modes as shown in FIGS. 4A and 5A, respectively, the light passing through each of the image generating units 50, 60 and 70 is as shown in FIGS. 4B and 5B, respectively. Since the same polarization change is performed, the wave plates 53, 63, 73, compensators 55, 65, 75 and the liquid crystal display device 57 of each image generating unit 50, 60, 70 are subjected to the same polarization change. All of the light passing through the polarizing beam splitters 51, 61, and 71 passes through the polarizing beam splitters 51, 61, and 71, and there is no light incident toward the dichroic beam splitter 80. do.

FIG. 6 is a schematic view illustrating an optical arrangement of a reflective project apparatus according to a second embodiment of the present invention, and the reflective project apparatus and actual material according to the first embodiment of the present invention described with reference to FIGS. 1 to 5b. The same feature is that the polarization transducer 100 is further provided on the optical path between the light source 10 and the first dichroic mirror 41. Here, the same reference numerals as in FIG. 1 denote the same members.

In the present exemplary embodiment, as illustrated in FIG. 7, the polarization converter 100 includes a microlens array 101 for focusing incident light and a beam separation member 110 provided to face the microlens array 101. And a half-wave plate array for converting the polarization of the incident light.

The beam splitting member 110 includes a first mirror surface 111 provided in an array corresponding to the microlens array 101 so as to transmit and reflect incident light according to its polarization, and the first mirror surface 111 is reflected from each of the first mirror surfaces 111. The second mirror surface 113 is provided in an array so as to reflect back the reflected light and proceed in parallel with the light transmitted through the first mirror surface 111. For example, the first mirror surface 111 transmits light of p-polarized light and reflects light of s-polarized light.

Each half-wave plate 120 of the half-wave plate array is disposed on the path of the light transmitted or reflected through the first mirror surface (111). That is, the beam splitting member 110 is disposed at equal intervals on the exit side. FIG. 7 shows an example in which the half-wave plate 120 is disposed on a path of light passing through the first mirror surface 111. In this case, the light transmitted through the first mirror surface 111, for example, light of p-polarized light, has its polarization converted by 90 degrees and becomes s-polarized light. Therefore, all the light passing through the polarization converter 100 becomes the light of s-polarized light. Here, the half-wave plate array may be provided integrally bonded to the exit side of the beam separation member 110.

The polarization converter 100 according to the present exemplary embodiment may further include a shielding member array including a plurality of shielding members 125 disposed at equal intervals on the incident side of the beam separation member 110. Each of the shielding members 125 limits the width of the light emitted from each microlens so that the light incident from the microlens array 101 does not directly enter the second mirror surface 113 and is incident on the beam separation member 110. do.

Meanwhile, as illustrated in FIG. 8, the polarization converter 100 may include a polarization beam splitter 210, a reflection member 220, and a half wave plate 230. The polarization beam splitter 210 transmits and reflects incident light incident from the light source 10 toward the first and second light 211 and 212 according to the polarization thereof. Here, the first light 211 is, for example, p-polarized light and the second light 212 is, for example, s-polarized light.

For example, the reflective member 220 reflects the second light 212 so that the two lights 211 and 212 are parallel to each other. The half-wave plate 230 is disposed on, for example, the path of the first light 211 to convert the polarized light of the incident light by 90 degrees.

Therefore, all the light via the polarization converter 100 as described above becomes the light of s polarization.

The reflective project apparatus according to the second embodiment of the present invention as described above selectively converts the polarization of the incident light so that the incident light is emitted as one polarized light, thereby using all the light emitted from the light source 10. Use efficiency is high.

The reflective project apparatus according to the present invention as described above employs a polarizing beam splitter as the optical path converting means, so that the illumination optical system and the projection optical system, that is, the optical axis optical system where the optical axes of the light source and the projection lens unit coincide, Easy to design

In addition, in the reflective project apparatus according to the present invention, each image generating unit includes a wave plate and a compensator between the polarizing beam splitter and the liquid crystal display element, and each image includes a compensator and a liquid crystal display element having approximately the same liquid crystal layer thickness. By making the thickness of the liquid crystal layer of the generation part have a predetermined ratio, almost perfect black / white can be realized and contrast can be increased.

In addition, when a polarization converter is provided on the optical path between the light source and the first dichroic mirror to selectively convert the polarized light of the incident light to be emitted as light of one polarized light, the light utilization efficiency is high.

Claims (8)

A light source for generating and projecting light; First and second dichroic mirrors which transmit and reflect incident light according to the wavelength region to separate the first to third color lights; First to third image generating units for generating images for each color using the first, second or third color light incident; A dichroic beam splitter having first and second mirror surfaces selectively transmitting or reflecting light according to a wavelength such that light incident through the first, second and third image generating units is emitted in one direction; And a projection lens unit configured to enlarge and project the light incident from the dichroic beam splitter toward the screen. The first to third image generating unit, respectively A polarization beam splitter for transmitting or reflecting the incident color light according to the polarization thereof to convert a traveling path of the incident light; A liquid crystal display device for generating and reflecting an image for each color from color light incident through the polarization beam splitter; A wavelength plate disposed on an optical path between the polarization beam splitter and the liquid crystal display device to change the polarization of incident light; And a compensator disposed on an optical path between the polarization beam splitter and the liquid crystal display device. The reflective project apparatus according to claim 1, wherein each of the liquid crystal display elements is a ferroelectric liquid crystal display element. The reflective project apparatus according to claim 1 or 2, wherein each compensator includes a liquid crystal layer having a thickness substantially equal to that of each corresponding liquid crystal display element. 4. The reflective project apparatus according to claim 3, wherein a thickness of the liquid crystal layer of the image generating unit for generating red, green, and blue images, respectively, is approximately 1.36: 1: 0.84. The reflective project apparatus according to claim 1, wherein each of the wave plates is a half wave plate for each color light. The reflective project apparatus according to claim 1, further comprising a polarization converter for converting incident light into light of one polarization on the optical path between the light source and the first dichroic mirror. The method of claim 6, wherein the polarization converter, A microlens array for focusing incident light; A first mirror surface that transmits and reflects incident light according to its polarization, and a second mirror surface that reflects the light reflected from the first mirror surface so that the light passes through the first mirror surface so as to correspond to the microlens array; A beam separation member having two mirror surfaces arranged in an array; And a half-wave plate array disposed on a path of light transmitted or reflected through the first mirror surface to convert polarized light of incident light, and converts the light emitted from the light source into light of one polarized light to enter the first dichroic mirror. Reflective project device, characterized in that. The method of claim 6, wherein the polarization converter, A polarization beam splitter which transmits and reflects the light incident from the light source toward the first and second light according to the polarization; A reflecting member for reflecting the first or second light so that the two lights travel in parallel with each other; And a half-wave plate disposed on the path of the first or second light to convert the polarized light of the incident light, and converting the light emitted from the light source into light of one polarized light to enter the first dichroic mirror. Reflective project device.