KR19990002347A - Transmissive Project Device - Google Patents

Abstract

Disclosed is a transmissive project device capable of increasing the brightness of light projected on a screen.

The disclosed transmissive project device includes a light source for generating and emitting light, and a light of the first circularly polarized light component transmitted and the light of the second circularly polarized light component of the incident light, which is disposed to be inclined at a predetermined angle with respect to the light source, to propagate incident light. Optical path converting means for converting a path, first and second polarization converting means for converting the first light transmitted through the optical path converting means and the second light reflected from the optical path converting means into linearly polarized light; Synthesis means for refracting and transmitting the first and second light incident from the first and second polarization conversion means, respectively; and a liquid crystal display device disposed adjacent to the synthesis means to generate and transmit an image; And a projection lens unit disposed adjacent to the element to enlarge and project the incident light toward the screen.

Description

Transmission type project device

The present invention relates to a transmissive project device, and more particularly, to a transmissive project device that can increase the brightness of the light projected on the screen.

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.

1 is a schematic diagram showing an optical arrangement of a conventional reflective project apparatus. As shown in the drawing, a conventional reflective project apparatus includes a light source 10 for generating and irradiating light, a color wheel 20 for selectively transmitting a predetermined color of incident light, and a scrambler for mixing the incident light to form a uniform light beam ( 30, a focusing lens 32, a collimating lens 34, a polarizing beam splitter 40, a display element 50 for generating an image, and a projection lens unit 60 for magnifying and projecting incident light. It is configured by.

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 drive motor 21 on the optical path between the light source 10 and the scrambler 30, and the red (R), green (G) and blue (B). Three colors are evenly distributed throughout the wheel. The color wheel 20 is rotated a predetermined number of times while one screen is formed on a screen (not shown).

The scrambler 30 mixes the incident light by diffused reflection so that the brightness distribution becomes uniform 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. Convert That is, light incident from the light source 10 side is selectively transmitted or reflected depending on its polarization component, that is, p- or s-polarized light. 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 liquid crystal display (FLCD: Ferroelectric Liquid Crystal Display) employing a ferroelectric liquid crystal having excellent response speed characteristics is employed. The light transmitted through the ferroelectric liquid crystal layer of the display element 50 is reflected by the reflecting plate of the display element 50 and passes through the ferroelectric liquid crystal layer again to the polarization beam splitter 40. In this case, light passing through the ferroelectric liquid crystal layer is driven and polarized by each pixel unit to display an image.

Among the light reflected by the display device 50 and re-injected into the polarization beam splitter 40, the light whose polarization direction is changed by 90 degrees is reflected by the mirror surface 41 of the polarization beam splitter 40 and is projected to the projection lens unit. Heading toward (60), it passes through this projection lens unit 60 and is projected onto a screen (not shown).

In the conventional reflective project device configured as described above, a polarizing beam splitter 40 is installed on an optical path to branch incident light according to its polarization component, and a color wheel 20 is provided on the optical path to implement a color. Thus, the screen is sequentially irradiated with three colors to realize one screen. At this time, since the incident angle allowable range of the polarizing beam splitter 40 for branching incident light according to its polarization component is small, parallel light should be incident on the polarizing beam splitter 40. The polarizing beam splitter 40 must be arranged so that parallel light can be incident vertically. However, it is difficult to produce parallel light that satisfies the incident angle allowable range of the polarizing beam splitter 40, and when the polarizing beam splitter 40 is inclined due to mechanical tolerances, the incident light splits according to the polarization component. Not easy to do In addition, the conventional reflective project apparatus as described above has a light efficiency corresponding to 1/6 of the amount of light emitted from the light source 10, and thus, there is a problem in that the brightness of the image projected on the screen is lowered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a transmission type project apparatus capable of branching incident light according to its polarization component and improving image brightness.

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

2 is a view schematically showing an optical arrangement of a transmission type project apparatus according to an embodiment of the present invention;

3A is a view illustrating another example of the first polarization conversion means of FIG. 2;

3B is a view illustrating another example of the second polarization conversion means of FIG. 2;

4 is a view showing an optical arrangement of a transmission project apparatus according to another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

110 Light source 120 Light path conversion means

121,330 cholesteric liquid crystal cell 125a, 125b ... first and second light

131,135 ... first and second polarization conversion means 132,133,136,137

134,138 Half-wave plate 140 Synthetic means

141 prism 143 beam splitter

143a ... total slope 143b ... irradiance

145 ... light mixing means 150 ... liquid crystal display element

Projection lens unit 250, 260 First and second liquid crystal display elements

300 ... first optical path changing means 310,320 ... first and second quarter-wave plates

According to an aspect of the present invention, there is provided a transmission type project apparatus including: a light source generating and emitting light; An optical path changing means disposed at an angle with respect to the optical axis of the light incident from the light source, for transmitting or reflecting the light of the predetermined wavelength region according to the circularly polarized light component of the incident light to split into the first and second light; First and second polarization conversion means for converting the first and second light into linearly polarized light, respectively; Synthesizing means for synthesizing light incident from the first and second polarization converting means; A liquid crystal display device disposed adjacent to the synthesizing means for generating and transmitting an image; And a projection lens unit for expanding and projecting the incident light transmitted through the liquid crystal display device toward the screen.

In addition, the transmission project apparatus according to the present invention comprises a light source for generating and emitting light; A first optical path converting means arranged to be inclined at a predetermined angle with respect to the optical axis of the light incident from the light source, and transmitting or reflecting the light of a predetermined wavelength region of the incident light according to the circularly polarized light component to branch into the first and second light; and; First and second polarization conversion means for converting the first and second light via the first light path conversion means into linearly polarized light, respectively; First and second liquid crystal display elements for generating and transmitting an image by inputting the first and second light via the first and second polarization converting means; Second optical path conversion means disposed adjacent to the first and second liquid crystal display elements to polarize and synthesize the first and second light incident from the first and second liquid crystal display elements; And a projection lens unit disposed adjacent to the second light path converting means to enlarge and project the incident light toward the screen.

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

2 is a view schematically showing an optical arrangement of a transmission type project apparatus according to an embodiment of the present invention.

Referring to the drawings, the reflective project apparatus according to an embodiment of the present invention is a light source 110 for generating and emitting light, the optical path converting means 120 for converting the traveling path of the incident light, and polarizing the incident light First and second polarization conversion means 131 and 135, a synthesizing means 140 for synthesizing light, a liquid crystal display device 150 for generating and transmitting an image, and incident light toward a screen (not shown) And a projection lens unit 160 for projecting.

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 the light is focused, as another focal point, or the lamp 111 as the focal point. The light emitted from and reflected by the reflector 113 may be a parabolic mirror that is to be parallel light.

The optical path converting means 120 is disposed to be inclined at an angle with respect to the optical axis of the light incident from the light source 110 so as to convert the advancing path of the incident light, and the three cholesteric liquid crystal layers 121a and 121b are disposed. It is preferable to provide the cholesteric liquid crystal cell 121 containing 121c. The first cholesteric liquid crystal layer 121a transmits or reflects the light of the first wavelength region emitted from the light source 110 to the first and second light according to the circularly polarized light component. Each of the second and third cholesteric liquid crystal layers 121b and 121c transmits or reflects the light of the second and third wavelength regions emitted from the light source 110 according to the circularly polarized light component, respectively, so that the first and the first And branches to the second light. In this case, each of the first, second, and third cholesteric liquid crystal layers 121a, 121b, and 121c has a pitch of the cholesteric liquid crystal having light of the first, second, and third wavelength regions. For example, it is provided corresponding to the center wavelength of red (R) light, green (G) light, and blue (B) light. In this case, the reflectance with respect to the circularly polarized light component is maximized, and the light incident from the light source 110 can be split into the first and second light with almost no loss.

The first polarization converting means 131 converts the first light 125a transmitted through the optical path converting means 120 into a linearly polarized light. The second polarization converting means 135 converts the second light 125b reflected by the optical path converting means 120 into linearly polarized light. As shown in FIG. 2, the first and second polarization converting means 131 and 135 are quarter-wave plates 132 for converting the first and second light into first and second linearly polarized light, respectively. 136. In this case, by appropriately positioning the fast axes of the quarter-wave plates 132 and 136, the light of the first and second linearly polarized light can be the same linearly polarized light.

3A and 3B illustrate another example of the first and second polarization conversion means 131 and 135, respectively. 3A is an example of replacing the first polarization conversion means 131 of FIG. Here, the first polarization conversion means 131 is a quarter-wave plate 133 for converting the first light (125a) into the light of the first linearly polarized light, and the second linear line by rotating the polarization direction of the first linearly polarized light The half-wave plate 134 for converting to polarized light may be provided. FIG. 3B is an example of replacing the second polarization conversion means 135 of FIG. 2. Here, the second polarization converting means 135 includes a quarter-wave plate 137 for converting the second light 125b into the light of the second linearly polarized light, and rotates the polarization direction of the second linearly polarized light to the first straight line. The half-wave plate 138 for converting the light into polarized light may be provided. On the other hand, for example, the second light 125b is reflected by the reflection mirror 127 so that the first and second lights 125a and 125b may run in parallel with each other.

Therefore, the first and second lights 125a and 125b, which are converted into the same linearly polarized light by the first and second polarization converting means as described above, are advanced side by side and are incident on the synthesizing means 140. Here, the first and second polarization conversion means 131 and 136 are provided so as to correspond to the wavelength of light having a small amount of emitted light among the light of the first, second and third wavelength regions emitted from the light source 110. In this case, since the color purity and color balance of the image can be corrected, the color correction filter is unnecessary.

The synthesizing means 140 may include a prism 141 for synthesizing the first and second light 125a and 125b incident from the first and second polarization conversion means 131 and 135. . The prism 141 includes an incidence surface 141a including a first incidence area and a second incidence area spaced apart from the first incidence area by a predetermined interval, and each of the first and second inclinations with respect to the incidence plane. Refractive surfaces 141b and 141c are provided. The first light 125a is incident on the first incident region, and the second light 125b is incident on the second incident region. The incident first and second lights 125a and 125b are refracted and emitted toward each other by the refracting surfaces 141b and 141c.

Here, the first and second lights 125a and 125b disposed between the synthesizing unit 140 and the liquid crystal display device 150 and refracted by the prism 141 are incident to diverge / converge or diffusely diffuse and are uniform. It is preferable to further include a light mixing means 145 to be light. As the light mixing means 145, a rectangular parallelepiped scrambler having a glass having an incidence plane and an outgoing plane perpendicular to the optical axis can be employed to diffuse the incident light to make uniform light. The aspect ratio of the exit surface of the scrambler is proportional to the aspect ratio of the liquid crystal display device. When the scrambler is employed, the reflector is preferably an ellipsoid.

It is preferable to further include a relay lens unit 147 on the optical path between the synthesizing means 140 and the liquid crystal display device 150 to focus the incident light into parallel light. The relay lens unit 147 focuses a collimating lens 148 for emitting incident light and a diverging light incident on the optical path between the focusing lens 148 and the liquid crystal display element 150 to collide with the incident light. Collimating lens 149 to be included. In addition, a condensing lens unit (not shown) for adjusting the width of incident light may be further provided on the optical path between the relay lens unit 147 and the liquid crystal display device 150. Therefore, the light emitted from the light source 110 side is adjusted to a width of the liquid crystal display device 150 while passing through the relay lens unit 147 and / or the condensing lens unit, and is incident on the liquid crystal display device 150. do.

The liquid crystal display device 150 is a transmission type, and is driven in units of pixels according to an applied voltage, and a polarizing plate is provided on the front surface thereof. Therefore, the linearly polarized incident light is polarized by each pixel unit and the brightness of the polarizing plate is controlled to be directed toward the projection lens unit 160.

The projection lens unit 160 enlarges and projects light incident through the liquid crystal display device 150 toward a screen (not shown).

Hereinafter, the operation of the transmission type project apparatus according to an embodiment of the present invention with reference to FIG.

The light emitted from the light source 110 is transmitted or reflected by the light path converting means 120 according to the circularly polarized state, and is split into the first and second light 125a and 125b. The first and second light 125a and 125b are converted into light of the same linearly polarized light by the first and second polarization converting means 131 and 135, respectively. The first and second lights 125a and 125b, which are converted into the same linearly polarized light, are synthesized by the synthesizing means 140, and the width thereof is adjusted via the relay lens unit 147 and / or the condenser lens unit. And incident on the liquid crystal display device 150. The incident light is polarized by the pixel unit in the liquid crystal display device 150, and the light whose polarization state is changed by 90 degrees or the light whose polarization state is not changed is transmitted through the polarizing plate provided on the front surface of the liquid crystal display device 150. The projection lens unit 160 is directed toward the screen by the projection lens unit 160.

4 is a view showing an optical arrangement of a transmission project apparatus according to another embodiment of the present invention.

Referring to the drawings, a transmission type project apparatus according to another embodiment of the present invention, the light source 110 for generating and outputting light, the first light path conversion means 120 for converting the traveling path of the incident light, and the polarization of the incident light First and second polarization conversion means 131 and 135 for converting states, first and second liquid crystal display elements 250 and 260 for generating and transmitting an image, and agents for polarizing and combining incident light; And a two-light path converting means 300 and a projection lens unit 160 for projecting the incident light toward the screen (not shown). Here, the light source 110 and the first light path converting means 120 have the same structure and function as those of the embodiment described with reference to FIG.

The first polarization converting means 131 is disposed between the first light path converting means 120 and the first liquid crystal display device 250 to convert the first light 125a into polarized light and convert the light into linearly polarized light. give. The second polarization converting means 135 is disposed between the first light path converting means 120 and the second liquid crystal display device 260 to polarize the second light 125b to convert the first light 125b. The light is converted into linearly polarized light which is the same as or perpendicular to 125a). The first and second polarization conversion means 131 and 135 may include quarter wave plates 132 and 136, respectively, as shown in FIG. 4. In addition, as illustrated in FIGS. 3A and 3B, a half-wave plate may be further provided on the optical path of the first or second light 125a and 125b. Here, the first and second polarization conversion means 131 and 135 are substantially the same as the first and second polarization conversion means 131 and 135 of the embodiment described with reference to FIGS. 2, 3A, and 3B. Therefore, the description is omitted.

The first and second liquid crystal display elements 250 and 260 are converted into light linearly polarized by the first and second polarization conversion means 131 and 135, respectively, and are incident to the first and second light 125a. An image 125b is input to generate and transmit an image. In this case, the first liquid crystal display device 250 may be provided with a color filter to generate and transmit a color image. The second liquid crystal display device 260 is preferably provided to generate and transmit a luminance signal. At this time, the luminance signal is combined with the color image by the second light path converting means 300 and projected onto the screen to form a bright image. Herein, the structures and functions of the first and second liquid crystal display devices 250 and 260 may be changed.

The second light path converting means 300 is disposed adjacent to the first and second liquid crystal display elements 250 and 260 and is incident from the first and second liquid crystal display elements 250 and 260. The first and second lights 125a and 125b are polarized and synthesized. Here, the second light path converting means 300 includes first and second quarter-wave plates 310 and 320 and a cholesteric liquid crystal cell 330. The first quarter wave plate 310 converts the first light incident from the first liquid crystal display device 250 into light of a first circularly polarized light component. The second quarter-wave plate 320 converts the first light emitted from the second liquid crystal display device 260 into light of a second circularly polarized light component different from the first circularly polarized light. The cholesteric liquid crystal cell 330 includes first, second and third cholesteric liquid crystal layers 330a, 330b, and 330c. The first cholesteric liquid crystal layer 330a reflects or transmits light of a first wavelength region among light of the first and second circularly polarized light components incident from the first and second quarter-wave plate 310. . The second and third cholesteric liquid crystal layers 330b and 330c reflect or transmit light in the second and third wavelength regions, respectively. Here, the cholesteric liquid crystal cell 330 is substantially the same as the optical path converting means 120 of the embodiment described with reference to FIG. 2.

On the other hand, it is preferable to further include a relay lens unit (not shown) on the optical path between the light source 110 and the first optical path conversion means 120 to focus the incident light to be parallel light. This relay lens unit is substantially the same as the relay lens unit 147 of the embodiment described with reference to FIG.

Hereinafter, the operation of the transmission type project apparatus according to another embodiment of the present invention will be described with reference to FIG. 4.

The light emitted from the light source 110 is transmitted or reflected by the first light path converting means 120 according to the circularly polarized state, and is split into the first and second lights 125a and 126b. The first and second lights 125a and 125b are converted into linearly polarized light by the first and second polarization converting means 131 and 135 respectively. The first and second lights 125a and 125b converted to the linearly polarized light are polarized and transmitted in pixel units in the first and second liquid crystal display devices 250 and 260, respectively. The first and second light rays 125a and 125b passing through the first and second liquid crystal display elements 250 and 260 are respectively first and second in the first and second quarter wave plates 310 and 320. And light of the second circularly polarized light component. The light of the first and second circularly polarized light components is selectively reflected or transmitted in the cholesteric liquid crystal cell 330 according to the circularly polarized state to be synthesized and directed toward the projection lens unit 160. 160 is enlarged and projected toward the screen.

The transmission type project apparatus according to the present invention as described above can split incident light into the first and second light according to the circularly polarized light component by using the optical path converting means inclined with respect to the optical axis, so that the allowable range of the incident angle is Since both of the first and second light are used, the brightness of the image projected on the screen is greatly improved.

Claims (15)

A light source for generating and emitting light; An optical path changing means disposed at an angle with respect to the optical axis of the light incident from the light source, for transmitting or reflecting the light of the predetermined wavelength region according to the circularly polarized light component of the incident light to split into the first and second light; First and second polarization conversion means for converting the first and second light into linearly polarized light, respectively; Synthesizing means for synthesizing light incident from the first and second polarization converting means; A liquid crystal display device disposed adjacent to the synthesizing means for generating and transmitting an image; And a projection lens unit for expanding and projecting the incident light transmitted through the liquid crystal display device toward the screen. The optical path converting means according to claim 1, further comprising: a first cholesteric liquid crystal layer which transmits or reflects light of the first wavelength region of the incident light according to the circularly polarized light component to branch into first and second light; A second cholesteric liquid crystal layer which transmits or reflects light of the second wavelength region of the incident light according to the circularly polarized light component and splits it into first and second lights; A cholesteric liquid crystal cell comprising a third cholesteric liquid crystal layer which transmits or reflects light of a third wavelength region among incident light beams according to the circularly polarized light component and splits it into first and second light beams. Project device. The method of claim 1, wherein the first polarization converting means is a first half-wave plate for converting the first light via the light path converting means into linearly polarized light, And said second polarization converting means is a second quarter-wave plate for converting the second light via said optical path converting means into linearly polarized light. The method of claim 1, wherein the first polarization conversion means is a quarter-wave plate for converting the first light into light of the first linearly polarized light, The second polarization converting means includes a quarter wave plate for converting the second light into second linearly polarized light; A half-wave plate for converting the light of the second linearly polarized light into the light of the first linearly polarized light, And a light beam converted into one linearly polarized light is incident on the liquid crystal display. 2. The apparatus of claim 1, wherein the first polarization converting means comprises: a quarter wave plate for converting the first light into first linearly polarized light; A half-wave plate for converting light of the first linearly polarized light into a second linearly polarized light, The second polarization converting means is a quarter-wave plate for converting the second light into the light of the second linearly polarized light, And a light beam converted into one linearly polarized light is incident on the liquid crystal display. The incident surface as claimed in claim 1, wherein the synthesizing means comprises: a first incidence region into which the first light is incident, a second incidence region spaced apart from the first incidence region by a predetermined interval; ; A prism comprising: first and second refractive surfaces that are inclined with respect to the incidence surface such that the first and second light incident through the first and second incidence regions are refracted toward each other; Device. The transmissive project device according to claim 1, further comprising a light mixing means disposed between the synthesizing means and the liquid crystal display element to diverge / converge or diffusely reflect the first and second light to make uniform light. . 8. The transmission type project apparatus according to claim 7, wherein the light mixing means is a rectangular parallelepiped scrambler made of glass having an incident surface and an exit surface perpendicular to the optical path so that the incident light is diffusely reflected to become uniform light. A light source for generating and emitting light; A first optical path converting means arranged to be inclined at a predetermined angle with respect to the optical axis of the light incident from the light source, and transmitting or reflecting the light of a predetermined wavelength region of the incident light according to the circularly polarized light component to branch into the first and second light; and; First and second polarization conversion means for converting the first and second light via the first light path conversion means into linearly polarized light, respectively; First and second liquid crystal display elements for generating and transmitting an image by inputting the first and second light via the first and second polarization converting means; Second optical path conversion means disposed adjacent to the first and second liquid crystal display elements to polarize and synthesize the first and second light incident from the first and second liquid crystal display elements; And a projection lens unit disposed adjacent to the second light path converting means to enlarge and project the incident light toward the screen. 10. The liquid crystal display of claim 9, wherein the first optical path converting means comprises: a first cholesteric liquid crystal layer for transmitting or reflecting light of a first wavelength region among incident light beams according to the circularly polarized light component to branch into first and second light; ; A second cholesteric liquid crystal layer which transmits or reflects light of the second wavelength region of the incident light according to the circularly polarized light component and splits it into first and second lights; A cholesteric liquid crystal cell comprising a third cholesteric liquid crystal layer which transmits or reflects light of a third wavelength region among incident light beams according to the circularly polarized light component and splits it into first and second light beams. Project device. 10. The method of claim 9, wherein the first polarization converting means is a first half wave plate disposed between the first light path converting means and the first liquid crystal display element to convert incident first light into linearly polarized light, The second polarization converting means is a transmissive project device, characterized in that the second quarter wave plate disposed between the second light path converting means and the second liquid crystal display element converts the incident second light into linearly polarized light. . 12. The transmissive project device according to claim 11, wherein the first polarization converting means further comprises a half-wave plate for converting one linearly polarized light into another linearly polarized light. 12. The transmissive project device according to claim 11, wherein the second polarization converting means further comprises a half-wave plate for converting one linearly polarized light into another linearly polarized light. 10. The liquid crystal display device of claim 9, wherein one of the first and second liquid crystal display elements includes a color filter to generate a color image, and the other liquid crystal display element generates a luminance signal to brighten the image projected on the screen. Transmissive project device, characterized in that. 10. The display device of claim 9, wherein the second optical path converting means comprises: a first quarter-wave plate for converting first light incident from the first liquid crystal display device into light of a first circularly polarized light component; A second quarter-wave plate for converting the second light incident from the second liquid crystal display element into light of the first circularly polarized light component and light of a second circularly polarized light component whose rotation direction is different; A first cholesteric liquid crystal layer that reflects or transmits light of a first wavelength region among the light of the first and second circularly polarized components, and light of a second wavelength region among the light of the first and second circularly polarized components A cholesteric liquid crystal layer including a second cholesteric liquid crystal layer that reflects or transmits light, and a third cholesteric liquid crystal layer that reflects or transmits light in a third wavelength region among the light of the first and second circularly polarized light components. Transmissive project device comprising a; liquid crystal cell.