KR19990001774A - Reflective Project Device - Google Patents

Abstract

Disclosed is a reflective project apparatus that can increase light efficiency using a birefringent prism.

The reflective project device includes a light source for generating and emitting light; First and second birefringent prisms disposed to face each other on the optical path, and birefringent incident light according to the crystal direction to diverge the normal light and the abnormal light to convert light paths to have different optical paths; First and second image generating means disposed opposite each of the first and second birefringent prisms to generate and reflect an image from light passing through each of the first and second birefringent prisms; First and second phase delay plates disposed on an optical path between the first and second birefringent prisms and the first and second image generating means, respectively, for delaying a phase of transmitted light so that polarization characteristics of incident light are changed; Disposed adjacent to the second birefringent prism and formed by the first and second image generating means, respectively, and incident light through the first and second birefringent prisms and the first and second birefringent prisms to the screen It is configured to include; projection lens unit for magnifying and projecting.

Description

Reflective Project Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective project apparatus, and more particularly, to a reflective project apparatus that can increase light efficiency using a birefringent prism.

In general, a projector apparatus is an apparatus for projecting an image generated by an image generating means onto a screen by using a separate lighting device.

1 is a schematic view showing an optical arrangement of a conventional reflective projector device. As shown, a light source 10 for generating and irradiating light, a color wheel 20 for selectively transmitting a predetermined color of incident light, a scrambler 30 for mixing incident light to make uniform light, and a focusing lens ( 32), a collimating lens 34, a polarizing beam splitter 40 for converting the traveling path of incident light, a display element 50 for selectively reflecting incident light and an incident light screen (not shown) And a projection lens unit (60) for projecting on.

The light source 10 includes a lamp 11 for generating light such as a metal halide, xenon, and the like, and a reflector 13 for reflecting the light emitted from the lamp 11 and guiding a progress path thereof. The color wheel 20 is rotatably installed by the driving motor 21 on the optical path between the light source 10 and the scrambler 30, and is red (R), green (G), and blue (B). ) The three-color color filter is divided equally throughout the wheel. The color wheel 20 rotates corresponding to the response speed of the display element described later, and any one of R, G, and B color filters is disposed on the optical path according to the response speed of the display element.

The scrambler 30 is made to be uniform light by mixing the incident light by the diffuse reflection. The focusing lens 32 focuses and diverges the light passing through the scrambler 30 to enlarge the transmission width of the light. The collimating lens 34 converges divergent light incident to be parallel light.

The polarizing beam splitter 40 is disposed on an optical path between the collimating lens 34 and the display element 50, and passes through and reflects the incident light on the mirror surface 41 according to the polarization component of the incident light. To convert That is, the light incident from the light source 10 is selectively transmitted or reflected depending on the polarization component, that is, P polarization or S polarization. 1 shows an example in which light transmitted through the polarization beam splitter 40 is used as effective light. As the display device 50, a ferroelectric liquid crystal display (FLCD) having excellent response speed characteristics having a two-dimensional array structure is employed. The display element 50 has a plurality of reflective regions of a two-dimensional array structure, and is driven independently to form an image by modulating the polarization direction of incident light.

Light incident on the display device 50 is reflected back to the polarizing beam splitter 40. In this case, the light re-injected into the polarization beam splitter 40 is changed by the display element 50 in the polarization direction by 90 degrees, and is totally reflected on the mirror surface 41 of the polarization beam splitter 40 so as to project the lens. To the unit (60). This light passes through the projection lens unit 60 and is projected onto a screen (not shown).

As described above, the path of the image is converted by dualizing according to the polarization direction of the incident light, and since only the light in one polarization direction is used as the effective light, the utilization efficiency of the light is reduced. Such a reduction in light efficiency is an obstacle to the implementation of a display device requiring high luminance.

Accordingly, an object of the present invention is to provide a reflection type project apparatus which increases the utilization efficiency of light emitted from a light source by adopting a pair of birefringent prisms to replace the polarization beam splitter. .

1 is a schematic view showing an optical arrangement of a conventional reflective project apparatus.

2 is a schematic view showing an optical arrangement of a reflective project apparatus according to an embodiment of the present invention.

3 is a schematic view showing an optical arrangement of a reflective project apparatus according to another embodiment of the present invention.

Explanation of symbols for the main parts of the drawings

1 ... incident light 3 ... normal light 5 ... abnormal light

110 Light source 111 Lamp 113 Reflector

115 ... collimating lens 120 ... first birefringent prism 121 ... entrance

123 ... First critical plane 125 ... First entrance and exit plane

130 The second birefringent prism 131 The second entrance and exit plane 133 The second critical plane

135.Exiting plane 140 ... First image generating means

150 second image generating means 160 first phase delay plate

170 2nd phase delay plate 180 Projection lens unit 190 Color selection means

191 Color filter 193

In order to achieve the above object, the reflective project device according to the present invention comprises a light source for generating and emitting light; Arranged opposite to each other on the optical path and birefringed the incident light according to the crystal direction and split into the first and second light beams, and the traveling path of the light so that the branched first and second light beams have different optical paths. Converting first and second birefringent prisms; First and second image generating means arranged to face each of said first and second birefringent prisms to generate and reflect an image from light emitted from said light source and via said first and second birefringent prisms, respectively; First and second birefringent prisms disposed on an optical path between the first and second image generating means, respectively, for delaying a phase of transmitted light such that polarization characteristics of the first and second light beams are changed; A second phase delay plate; Disposed adjacent to the second birefringent prism and formed in the first and second image generating means, respectively, and incident through the first and second phase retardation plates and the first and second birefringent prisms, respectively. And a projection lens unit for expanding and projecting light onto the screen.

In addition, it is preferable that the reflective project device according to the present invention further comprises a color selection means on the optical path between the second birefringent prism and the projection lens unit to realize the color image.

Hereinafter, a reflective project apparatus according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic view showing an optical arrangement of a reflective project apparatus according to an embodiment of the present invention.

As shown, the present invention provides a light source 110, the first and second birefringent prisms 120, 130 for converting the traveling path of the light emitted from the light source 110, and generating and reflecting an image with incident light The first and second image generating means 140 and 150, the first and second phase delay plates 160 and 170 respectively disposed on the optical path to retard the phase of the incident light, and the incident light to the screen (not shown). And a projection lens unit 180 to enlarge and project the image.

The light source 110 includes a lamp 111 for generating light and a reflector 113 for reflecting the light emitted from the lamp 111 and guiding a path of the light. The reflector 113 is an ellipsoidal mirror having the position of the lamp 111 as one focal point and the point where light is focused as another focal point, or the lamp 111 as the focal point and the lamp 111 as the focal point. It may be a parabolic mirror so that the light emitted from the light reflected by the reflecting surface is a parallel light. 2 illustrates an example in which an ellipsoidal mirror is used as the reflector 113. The collimating lens 115 is formed such that light emitted from the light source 110 and reflected from the ellipsoidal mirror becomes parallel light. It is further provided.

The first and second birefringent prisms 120 and 130 are disposed to face each other on an optical path, and the incident light 1 is birefringed into the normal light 3 and the abnormal light 5 according to the crystallization direction, and thus the light travels. Convert the path. Here, the normal ray 3 refers to a ray having the same refractive index because the traveling speed of the ray is constant regardless of the crystal optical axis directions of the first and second birefringent prisms 120 and 130. On the other hand, the abnormal light beam 5 is a light beam having a different refractive index according to the direction of incident light with respect to the crystal beam axis by changing the traveling speed of the light beam along the crystal beam axis direction of the first and second birefringent prism 120,130. it means.

The first birefringent prism 120 is disposed on an optical path between the light source 110 and the first image generating means 140, and the incident light 1 from the light source 110 is abnormal with the normal light 3. An incidence surface 121 birefringed by the light rays 5 to have different optical paths, a first critical surface 123 for reflecting the incident normal light 3, and a transmission of the abnormal light 5, and the It is disposed to be inclined with respect to the first image generating means 140 has a first entrance and exit surface 125 for refracting and transmitting the incident light. It is preferable that the first birefringent prism 120 has a trapezoidal quadrangular column shape having the first critical surface 123 as a base.

Here, the inclination angles of the incident surface 121 and the first entrance and exit surface 125 are determined by the refraction angles of the normal light beam 3 and the abnormal light beam 5 and the critical angle of the first critical plane 123. That is, the normal light 3 is incident at an angle greater than or equal to the critical angle of the first critical plane 123 and totally reflected by the first critical plane 123, and the abnormal light 5 is smaller than the critical angle of the first critical plane 123. The light is incident at a small angle to refraction through the first critical surface 123. The normal light and the abnormal light are light of linearly polarized light orthogonal to each other.

The second birefringent prism 130 has a second critical plane 133, a second entrance and exit plane 131, and a projection plane 135, and has a trapezoidal rectangular pillar having the second critical plane 133 as a bottom surface thereof. It is preferable that it is a shape. The second critical surface 133 is disposed to face the first critical surface 123, and the abnormal light beam 5 transmitted through the first birefringent prism 120 is refracted and transmitted through the second phase retardation plate. The normal light of which the birefringence characteristic changed through the 170 and the second image generating means 150 is reflected. The second entrance and exit surface 131 is disposed to be inclined with respect to the second image generating means 150, and the incident light is refracted and transmitted at different angles according to its birefringence property. The exit surface 135 is disposed to be inclined with respect to the exit optical axis, is reflected by the first and second image generating means 140, 150, and the first and second exit surface (125, 131) and In addition, the beams incident through the first and second critical surfaces 123 and 133 are refracted and transmitted toward the projection lens unit 180.

As shown in FIG. 2, the first and second birefringent prisms 120 and 130 reflect normal light from each of the first and second critical surfaces 123 and 133 and transmit the abnormal light. Each of the first and second critical surfaces 123 and 133 may reflect the abnormal light and transmit the normal light. The birefringence properties of each of the first and second birefringent prisms 120 and 130 are determined by the material thereof.

The first phase delay plate 160 is disposed on an optical path between the first entrance and exit surface 125 and the first image generating means 140, and the second phase delay plate 170 is disposed on the second path delay plate 170. It is disposed on the optical path between the entrance and exit surface 131 and the second image generating means 150. Each of the first and second phase delay plates 160 and 170 delays the phase of incident light to change the polarization direction of the light. Herein, the first and second phase delay plates 160 and 170 may change λ / 4 to change the incident linearly polarized light into circularly polarized light and the incident circularly polarized light into linearly polarized light. It is preferable that it is a wave plate.

The first image generating unit 140 refracts the first entrance and exit surface 125, generates an image from the light incident through the first phase delay plate 160, and generates the first entrance and exit surface ( And reflect back to 125). The second image generating means 150 refracts the second entrance and exit surface 131, generates an image from the light incident through the second phase delay plate 170, and reflects it again.

To this end, it is preferable that each of the first and second image generating means 140 and 150 is a ferroelectric liquid crystal display device (hereinafter, referred to as FLCD) that is independently driven and includes pixels of a two-dimensional array structure.

In the FLCD, light reflected from a pixel driven with respect to incident light having the same polarization direction and light reflected from a non-driven pixel have different polarization directions. For example, when the light of the normal light directed to the first entrance and exit surface 125 is incident on the FLCD through the λ / 4 wavelength plate, the light reflected from the driven pixel is an abnormal light and is reflected from the non-driven pixel. The light is a normal light whose polarization direction does not change.

Each of the first and second image generating means 140 and 150 may employ a digital mirror device (DMD) including mirrors having a two-dimensional array structure in addition to the FLCD. In this case, each of the mirrors is driven independently and generates an image by varying the angle of reflection for incident light.

Here, since the above-described DMD and FLCD are widely known, the configuration and detailed description thereof will be omitted.

The projection lens unit 180 is disposed between the exit surface 135 of the second birefringent prism 130 and the screen (not shown), and is generated by the first and second image generating means 140 and 150. The image incident through the first and second birefringent prisms 160 and 170 is enlarged and projected toward a screen (not shown).

Referring to Figure 3, a reflective project apparatus according to another embodiment of the present invention will be described in detail. Here, the same reference numerals as in the above-described drawings represent the same or similar members having the same function and a detailed description thereof will be omitted.

According to a feature of the present embodiment, the apparatus further comprises a color selecting means 190 for sequentially selecting colors so as to implement a color image on the optical path between the light source 110 and the projection lens unit 180. There is this.

3 is a diagram illustrating an example in which a color selecting means 190 is provided on an optical path between the second birefringent prism 130 and the projection lens unit 180.

The color selecting means 190 selectively transmits incident light according to a wavelength region to determine a color. The color selecting means 190 is red (R), green (G), blue (B) tricolor or yellow (Y), cyan (C) selectively positioned on the optical path to selectively transmit incident light according to the wavelength. It is preferable to include a color filter 191 in which the three magenta (M) colors are arranged equally, and a driving unit 193 for rotating the color filter 191. The color filter 191 is rotated by the driving unit 193 so that the three colors are sequentially disposed on the optical path.

The color selecting means 190 may be disposed on an optical path between the light source 110 and the first birefringent prism 120.

Referring to Figure 2, the operation of the reflective project apparatus according to an embodiment of the present invention will be described.

The light rays generated by the lamp 111 and determined by the reflector 113 may be parallel rays while passing through the collimating lens 115. The light ray 1 is birefringed at the incident surface 121 of the first birefringent prism 120 and branches into the normal light 3 and the abnormal light 5 having different traveling paths.

The normal light beam 3 refracted by the incident surface 121 is incident and reflected at an angle greater than the critical angle of the first critical plane 123, and the abnormal light beam 5 is smaller than the critical angle of the first critical plane 123. Incident and refracted. The reflected normal ray 3 refracts the first entrance and exit surface 125. The refracted light beam passes through the first phase delay plate 160 as linearly polarized light, and becomes circularly polarized light. The light beam is reflected by the first image generating unit 140 in a state in which a selective polarization direction is determined according to whether each pixel of the first image generating unit 140 is driven, and the first phase delay plate 160 While passing through the light, the light becomes linearly polarized light. In this case, the light rays reflected by the driven pixels of the first image generating unit 140 are changed to 90 degrees, and the light rays reflected by the non-driven pixels are normal rays as they are. Therefore, the normal light beam and the abnormal light beam re-entered on the first entrance surface 125 have different light paths, and the normal light beam is reflected from the first critical plane 123, and the abnormal light beam is the first critical plane 123, The light penetrates the two critical surfaces 133 and the exit surface 135 toward the projection lens unit 180.

On the other hand, the abnormal light transmitted through the incident surface 121 and transmitted through the first critical surface 123 passes through the second critical surface 133 and the second entrance and exit surface 131 and the second phase It enters into the second image generating means 150 via the delay plate 170. The light reflected by the second image generating unit 150 has a selective polarization direction depending on whether each pixel is driven. Accordingly, the light rays reflected by the driven pixels among the light rays reflected by the second image generating means 150 and re-incident to the second entrance and exit surface 131 via the second phase delay plate 170 are The polarization direction is changed by 90 degrees to become normal light, and the light reflected from the non-driven pixel is an abnormal light as it is. Therefore, the normal light beam and the abnormal light beam re-incident on the second light exit surface 131 are branched to different light paths and are transmitted through refractive rays, and the normal light beam is reflected from the second critical surface 133 and the light exit surface 135. It passes through and is directed toward the projection lens unit 180. The abnormal light beam passes through the second critical surface 133, the first critical surface 123, and the incident surface 121.

As described above, the reflective project device according to the embodiment of the present invention can increase the utilization efficiency of light by using all the light emitted from the light source. In addition, the use of a polarizing beam splitter sensitive to the incident angle of light can be eliminated.

Claims (12)

A light source for generating and emitting light; Firstly disposed opposite to each other on the optical path and birefringed the incident light according to the crystal direction to split the normal light and the abnormal light, and converts the traveling path of the light so that the branched normal light and the abnormal light have a different optical path And a second birefringent prism; First and second image generating means arranged to face each of said first and second birefringent prisms to generate and reflect an image from light emitted from said light source and via said first and second birefringent prisms, respectively; First and second phase delay plates disposed on an optical path between the first and second birefringent prisms and the first and second image generating means, respectively, for delaying a phase of transmitted light so that polarization characteristics of incident light are changed. and; Disposed adjacent to the second birefringent prism and formed in the first and second image generating means, respectively, and incident through the first and second phase retardation plates and the first and second birefringent prisms, respectively. And a projection lens unit configured to enlarge and project light onto a screen. The light source of claim 1, wherein the light source is disposed opposite to the first birefringent prism and generates and emits light; Reflective project device characterized in that it comprises a reflector for allowing the light emitted from the lamp to proceed in one direction. The method of claim 1, wherein the first birefringent prism, An incidence surface disposed to be inclined with respect to the incident optical axis and refracting the incident light into normal rays and abnormal rays having different optical paths; A first critical surface that transmits one of the normal rays and the abnormal rays and reflects the other rays; And a first entrance and exit plane that is disposed to be inclined with respect to the first image generating means and refracts and transmits incident light. 4. The reflective project apparatus according to claim 3, wherein the first birefringent prism has a trapezoidal rectangular column shape having the first critical plane as a base. The method of claim 1, wherein the second birefringent prism, The light beams disposed opposite to the first critical plane and transmitted through the first birefringent prism are refracted and transmitted, and the light beams whose birefringence characteristics are changed through the second phase delay plate and the second image generating means are reflected. A second critical surface adapted to be made; A second entrance and exit surface disposed obliquely with respect to the second image generating means and configured to refractionally transmit the incident light; The projection lens unit disposed to be inclined with respect to the exiting optical axis, and reflected by the first and second image generating means, and the light incident through the first and second entrance and exit surfaces and the first and second critical surfaces; A reflective project device comprising a; exit surface for refraction transmission. 6. The reflective project apparatus according to claim 5, wherein the second birefringent prism has a trapezoidal rectangular column shape having the second critical plane as a base. The pixel of claim 1, wherein the first phase delay plate delays the phase of incident light so as to convert linearly polarized light into circularly polarized light and circularly polarized light into linearly polarized light. A reflective project device, characterized in that the lambda / 4 wavelength plate for selectively changing the birefringence characteristics of the incident light for each region. 2. The pixel of claim 1, wherein the second phase delay plate delays the phase of incident light so as to convert light of linearly polarized light into circularly polarized light and light of circularly polarized light into linearly polarized light. A reflective project device, characterized in that the lambda / 4 wavelength plate for selectively changing the birefringence characteristics of the incident light for each region. The method of claim 1, wherein each of the first and second image generating means, Arranged to face the first and second phase delay plates, respectively, each of which is independently driven to generate an image including pixels of a two-dimensional array structure for selecting a polarization direction, and toward the first and second phase delay plates. A reflection type project device, characterized in that the ferroelectric liquid crystal display element is reflected again. The method of claim 1, wherein each of the first and second image generating means, And a movable mirror device disposed to face the first and second phase delay plates, respectively, to generate an image including the two-dimensional array structure reflection mirrors which are independently driven to select the reflection direction of the incident light. Reflective project device characterized in that. The method according to any one of claims 1 to 10, And a color selection means disposed on an optical path between the light source and the projection lens unit to selectively transmit incident light according to a wavelength region to determine a color. 12. The color selecting means according to claim 11, characterized in that the color selecting means includes a plurality of color filters selectively positioned on the optical path to selectively transmit incident light according to the wavelength, and a driving unit for rotating the color filter. Reflective project device.