KR20090070362A - Device of decreasing unevenness of beam - Google Patents

Abstract

An apparatus for reducing beam uniformity using a birefringent medium is provided to reduce uniformity of an incident beam by using a phase difference plate to convert a polarized light beam into a round-shaped polarization state or an elliptical polarization state. A first polarization layer(310) separates an incident beam of n to a first polarized light beam of 2n. A phase difference plate(320) converts the first polarized light beam separated from the first polarization layer into a second polarized light beam of a round-shaped polarization state or an elliptical polarization state. The second polarized light beam(330) separates a second polarized light beam of 2n into a third polarized light beam of 4n.

Description

Device for Decreasing Unevenness of Beam

The present invention relates to an apparatus for reducing beam nonuniformity, and more particularly, to an apparatus for reducing beam nonuniformity using a birefringent medium.

In the display device using the optical modulator, the linear light formed while passing through the collimator lens and the cylinder lens may include a portion having a predetermined amount of noise or uniformity due to process error or component error. Therefore, the linear light may be formed in a non-uniform state, and it is obvious that the display quality is degraded due to the non-uniform linear light.

The present invention is to provide a beam nonuniformity reduction device that can reduce the nonuniformity of the incident beam.

In addition, the present invention is to provide a beam non-uniformity reduction device that can increase the uniformity of the circularly polarized beam, elliptical polarized beam or non-polarized beam irrespective of the polarization state of the incident beam.

In another aspect, the present invention is to provide a beam non-uniformity reduction device that can adjust the uniformity of the beam according to the degree of overlap of the birefringent plate.

In another aspect, the present invention is to provide a beam non-uniformity reduction device that can reduce the speckle.

Other objects of the present invention will become more apparent through the preferred embodiments described below.

According to an aspect of the present invention, there is provided a first polarization layer that separates n incident beams into 2n first polarization beams, where n is a natural number and n the incident beams are beams forming linear light; A phase difference plate for converting the first polarization beam separated from the first polarization layer into a second polarization beam in a circular polarization state or an elliptical polarization state; And a second polarization layer separating the 2n second polarization beams into 4n third polarization beams, wherein the 4n third polarization beams are irradiated in an overlapping manner.

The first polarizing beam may include an s-polarized beam and a p-polarized beam, and the n incident beams may be separated into n s-polarized beams and n p-polarized beams.

The third polarized beam may include an s-polarized beam and a p-polarized beam, and the 2n second polarized beams may be separated into 2n of the s-polarized beam and 2n of the p-polarized beam.

Here, the retardation plate may be a quarter wave plate.

Here, the retardation plate may be a phase retardation plate.

The first polarization layer and the second polarization layer may be formed of a material having the same refractive index, and the thickness of the first polarization layer may be twice the thickness of the second polarization layer.

The first polarization layer and the second polarization layer may be formed of a birefringent medium.

The apparatus may further include an additional retardation plate for converting the incident beam into a circular polarization beam or an elliptical polarization beam.

According to an embodiment of the present invention can provide a beam non-uniformity reduction device that can reduce the non-uniformity of the incident beam.

In addition, according to an embodiment of the present invention can provide a beam non-uniformity reduction device that can increase the uniformity of the circularly polarized beam, elliptical polarized beam or non-polarized beam irrespective of the polarization state of the incident beam.

In addition, according to an embodiment of the present invention can provide a beam non-uniformity reduction device that can adjust the uniformity of the beam according to the number of overlapping birefringent plate.

In addition, the present invention can provide a beam non-uniformity reduction device that can reduce the speckle.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

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

1 is a view showing a display device in which a beam nonuniformity reducing device according to an embodiment of the present invention is used.

1 is a system configuration diagram of a display device using an optical modulator according to a preferred embodiment of the present invention. Referring to FIG. 1, the R light source 105, the G light source 110, the B light source 115, the illumination system 120, the R light modulator 125, the G light modulator 130, the B light modulator 135, Light shielding means 140, controller 145, optical modulator controller 146, AD board 147, RGB serial controller 148, color combination optics 150, filter system 155, Galvanometer scanner 160, projection system 165 and screen 170 are shown.

The R light modulator 125, the G light modulator 130, and the B light modulator 135 correspond to the R light source 105, the G light source 110, the B light source 115, and the illumination system 120, respectively. The light generated from the light is reflected and diffracted to control the brightness of the light and the like.

The light shielding means 140 is provided at a position capable of opening and shielding the diffracted light emitted from the R light modulator 125, the G light modulator 130, and the B light modulator 135. According to a further embodiment, the light shielding means 140 is such that the R light source 105 to directly open and shield the respective light emitted by the R light source 105, G light source 110, B light source 115. The light source 110 may be positioned between the G light source 110 and the B light source 115 and the R light modulator 125, the G light modulator 130, and the B light modulator 135.

The controller 145 may include an optical modulator controller 146, an AD board 147, and an RGB serial controller 148. The light modulator controller 146 may control operations of the R light modulator 125, the G light modulator 130, and the B light modulator 135 in response to the input electrical signal. The AD board 147 may convert an analog signal into a digital signal to generate a required signal, and the RGB serial controller 148 controls the RGB light to be serially input. Herein, the control unit 145 directly controls the light shielding unit 140, so that the light modulators 125, 630, and 635 may synchronize with the light shielding unit 140.

Color combination optics 150 collect the beams passed or shielded by the light shielding means 140 and exit to the filter system 155. The filter system 155 is composed of a Fourier lens and a color screening filter.

Here, the Fourier lens collects the diffracted light of each diffraction order, and the dichroic filter passes the diffracted light of the desired order. The dichroic filter receives multiple diffraction beams through a Fourier lens, and then the multiplex diffraction beams have multiple diffraction beams having a predetermined diffraction order, more specifically zero order, + 1st order and -1st order diffraction orders. Only a plurality of diffraction beams having a predetermined diffraction order in the diffraction beams are selectively transmitted and emitted to the projection system.

2 is a configuration diagram of a display system in which a beam nonuniformity reducing device according to an embodiment of the present invention may be used. 2, an R light source 105, a G light source 110, a B light source 115, a collimator lens 245, a cylinder lens 250, an optical modulator 255, an illumination system 260, 265, 270, 275 and optical scanner 280 are shown. Although the present invention is not limited to the number of panels that can scan the beam emitted from the optical modulator 255, the following description focuses on the case of sequentially displaying RGB image signals using one panel element for convenience of description. do. In addition, unlike the embodiment of FIG. 1, it is assumed in the embodiment shown in FIG. 2 that the optical modulator is not divided according to the type (R, G, B) of the light source.

In the embodiment according to FIG. 2, the beam non-uniformity reduction device is not fixed in the display device and may be located at different locations according to various embodiments. The beam non-uniformity reduction device is shown at a specific position in FIG. 2. Not.

The R light source 105, the G light source 110, and the B light source 115 are devices that generate light, and may be, for example, light emitting diodes (LEDs), laser diodes (LDs), or lasers.

The collimator lens 245 and the cylinder lens 250 change the incident light into linear parallel light. That is, the collimator lens 245 changes the focused multiple beam into light parallel to the optical path direction. In addition, the cylinder lens 250 converts the balanced light into linear light in the horizontal direction. Incident light converted into linear light in the horizontal direction is incident on the light modulator 255 through the polarization beam splitter, the λ / 4 wave plate, and the X-prism.

That is, the cylinder lens 250 converts the balanced light into linear light in the horizontal direction so that the light incident from the condenser is incident horizontally into the corresponding light modulator 255 positioned horizontally in the optical path direction.

The collimator lens 245 may include a concave lens and a convex lens. The concave lens extends linear light incident from the cylinder lens 250 and enters the convex lens. The convex lens emits incident light incident from the concave lens into parallel light.

A beam nonuniformity reduction device (not shown) according to an embodiment of the present invention may be used to increase the uniformity of the beam emitted in the state of parallel light. The beam non-uniformity reduction device may be located at the front end or the rear end of the collimator lens 245 and the cylinder lens 250. Alternatively, the beam nonuniformity reduction device may be located between the collimator lens 245 and the cylinder lens 250.

The optical modulator 255 receives an optical modulator control signal transmitted from a driving signal processor (not shown) and operates according to the control signal. According to another embodiment of the present invention, the beam non-uniformity reducing device may be located in front of the light modulator 255, for example, between the cylinder lens 250 and the light modulator 255.

The illumination systems 260, 265, 270, and 275 may collect light, remove filters, speckles, and the like. That is, the zeroth order diffracted light is focused at a point when passing through the projection lens, where the + 1st order diffracted light is located above the position where the 0th order diffracted light is focused and the -1st order diffracted light is The zeroth order diffracted light is focused downward from the position where it is focused. The projection system includes a pair of projection lenses, a speckle remover and projects incident diffracted light onto the screen.

The optical scanner 280 rotates at a predetermined period and reflects the diffracted light emitted from the optical modulator 255 to project the predetermined screen. For example, the light scanner 280 may be a galvano mirror, polygon mirror or rotation bar. The optical scanner 280 may determine movement according to the same period as a signal for controlling the optical modulator 255.

3 is a view showing a beam nonuniformity reducing apparatus according to an embodiment of the present invention.

An apparatus for reducing beam nonuniformity according to an embodiment of the present invention includes a first polarization layer 310, a retardation plate 320, and a second polarization layer 330.

Further, according to another embodiment of the present invention, a second retardation plate (not shown), a third polarization layer (not shown), a third retardation plate (not shown), and a fourth polarization layer (not shown) behind the second polarization layer 330. C) may be further included. In this case, as the third and fourth polarization layers overlap, the incident beams are separated by polarization several times and then merged again, so that beam uniformity may be further improved.

However, in the present specification, even if the retardation plate and the polarizing layer overlap several times, the first polarizing layer 310 and the retardation plate 320 may be repeated since the features of the present invention, such as separating the beam and condensing again to reduce the beam unevenness, are repeated in the same manner. ) And only the second polarization layer 330 will be described.

In a display device using an optical modulator, an image is displayed using linear light. Therefore, according to the exemplary embodiment of the present invention, the incident beam forms linear light. The plurality of incident beams may be aligned, enlarged, reduced or superimposed in a predetermined direction through a process such as a mirror or a lens in the display device to form linear light.

The incident beam first enters the first polarization layer 310 to pass through the beam nonuniformity reducing device. The first polarization layer 310 and the second polarization layer 330 may be birefringent media. One example of a birefringent medium is calcite. Due to the nature of the birefringent medium, the birefringent medium separates one incident beam into two polarized beams. Since it is obvious to those skilled in the art that the beam passing through the birefringent medium is polarized and separated, detailed description thereof will be omitted.

In addition, the first polarization layer 310 and the second polarization layer 330 are not necessarily the same material. However, by adjusting the refractive index and thickness can be adjusted the intensity and amount of the separated beam. According to an embodiment of the present invention, the first polarization layer 310 and the second polarization layer 330 have the same refractive index, and the thickness of the first polarization layer 310 is equal to two of the thicknesses of the second polarization layer 330. It is a ship. The reason for doubling the thickness of the first polarization layer 310 to the thickness of the second polarization layer 330 is that the p-polarization beam and the s-polarization beam between the first polarization layer 310 and the second polarization layer 330. This is to double the beam separation interval of.

The beam incident on the first polarization layer 310 may be a circularly polarized or elliptically polarized beam. When a circularly polarized or elliptically polarized beam is incident, the first polarization layer 310 may separate the incident beam (hereinafter referred to as an incident beam) into two first polarization beams. The elliptical polarized beam may be an elliptical polarization beam tilted obliquely as compared to the direction of travel of the beam or perpendicular or horizontal to the direction of travel. There may be a method of tilting the beam by rotating the beam at an angle and using a phase retarder (including the phase retarder of the present invention).

If the incident beam in the linearly polarized state is incident on the first polarization layer 310, in order to polarize and separate the incident beam into the s-polarized beam and the p-polarized beam, first, the incident beam is converted into a circularly polarized or elliptical polarized state. There is a need. In this case, an additional retardation plate (not shown) may be provided in front of the first polarization layer 310. Therefore, the additional retardation plate uniformly converts the incident beam of any state that is not circularly polarized or elliptically polarized into the circularly polarized beam or the elliptical polarized beam, and then enters the first polarizing layer 310.

According to an embodiment of the present invention, the first polarized beam may be an s-polarized beam and a p-polarized beam. That is, the incident beam forming the linear light is separated into two first polarizing beams while passing through the first polarizing layer 310, and the two first polarizing beams are an s-polarized beam and a p-polarized beam.

The first polarization beam is converted into a circular polarization beam or an elliptic polarization beam by the phase difference plate 320 provided behind the first polarization layer 310. The circularly polarized or elliptically polarized beam by the retardation plate 320 is referred to as a second polarized beam hereinafter. According to an exemplary embodiment of the present invention, the retardation plate 320 may be a quarter wave plate (Quarter Wave Plate). The quarter wave plate can be used to modulate phase and intensity simultaneously.

Here, the s-polarized beam and the p-polarized beam emitted from the first polarizing layer 310 may be converted into an elliptical polarized beam while passing through the phase difference plate 320 which is a quarter wave plate. In this case, the second polarized beam converted from the s-polarized beam and the second polarized beam converted from the p-polarized beam are elliptically polarized beams whose directions are opposite to each other, or elliptical polarized beams tilted in directions perpendicular to each other.

As the retardation plate 320, a quarter wave plate may be used as described above, but a phase retardation plate may be used instead of a quarter wave plate.

The circularly polarized or elliptically polarized beam by the phase difference plate 320 is incident on the second polarization layer 330. The second polarization layer 330 separates the beam of the circularly polarized or elliptically polarized state into a third polarized beam again. The third polarized beam may also be an s-polarized beam and a p-polarized beam. However, the number of beams incident on the second polarization layer 330 is four times the number of beams incident on the first polarization layer 310 and the beam intensity is 1/4. In the same principle, the number of beams of the third polarization beam may be double and the beam intensity may be 1/2 compared to the first polarization beam incident on the retardation plate 320.

That is, the two beams (2n first polarizing beams) separated by two of the s-polarized beam and the p-polarized beam by the first polarizing layer 310 are again provided by the second polarizing layer 330. s-polarized beam and p-polarized beam) (4n third polarized beams). Therefore, one incident beam is consequently separated into four third polarized beams (two s-polarized beams and two p-polarized beams). In this process, the nonuniformity of the beam is also reduced to 1/2 to 1/4, and the beam nonuniformity of the final linear light is also reduced since four third polarization beams having reduced beam nonuniformity are irradiated with overlap.

If the retardation plate and the third or fourth polarization layer are additionally provided behind the second polarization layer 330, the incident beam is separated into eight or sixteen third polarization beams by polarization of the crosstalk and then again. Will merge. Therefore, the beam nonuniformity can be further reduced.

4 is a view showing a cross-sectional view of the beam passing through the beam nonuniformity reducing apparatus according to an embodiment of the present invention. Figure 4 (a) is a view showing an incident beam (beam appearing in the AA 'cross section of Figure 3) that does not pass through the beam non-uniformity reducing apparatus according to an embodiment of the present invention, Figure 4 (b) is a view of the present invention FIG. 3 is a diagram illustrating overlapping third polarization beams (beams appearing in the BB ′ cross-section of FIG. 3) after passing through a beam non-uniformity reducing device according to an embodiment. The cross section of the beam here refers to the cross section when the linear light is cut into a plane perpendicular to the traveling direction of the emitted linear light.

As described above, the 4n third polarizing beams are focused into n beams and the n beams form linear light. Referring to FIG. 4B, the linear light formed after the incident beam passes through the beam nonuniformity reducing device according to the embodiment of the present invention has a uniformity compared to the linear light according to the prior art shown in FIG. 4A. It can be seen that the increase. Since one beam is split into four beams and then merged again, four beams, whose beam unevenness is also reduced by 1/2 or more, are superimposed into one beam. Therefore, as described above, the linear light composed of the beam passing through the beam non-uniformity reduction device according to the embodiment of the present invention can be reduced.

While the above has been described with reference to a preferred embodiment of the present invention, the above-described embodiment of the present invention has been disclosed for the purpose of illustration, those skilled in the art will be described in the following claims It will be understood that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

1 is a view showing a display device in which a beam nonuniformity reducing device according to an embodiment of the present invention is used.

2 is a configuration diagram of a display system in which a beam nonuniformity reducing device according to an embodiment of the present invention may be used.

3 illustrates a beam nonuniformity reducing device according to an embodiment of the present invention.

4 is a view showing a cross-sectional view of the beam passing through the beam non-uniformity reduction device according to an embodiment of the present invention.

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

310: first polarization layer

320: phase difference plate

330: second polarization layer

Claims (8)

a first polarization layer that separates n incident beams into 2n first polarization beams, where n is a natural number and the n incident beams are beams forming linear light; A phase difference plate for converting the first polarization beam separated from the first polarization layer into a second polarization beam in a circular polarization state or an elliptical polarization state; And A second polarization layer separating the 2n second polarization beams into 4n third polarization beams, And 4n third polarizing beams are irradiated in a superimposed manner. The method of claim 1, The first polarizing beam includes an s-polarized beam and a p-polarized beam, and n said incident beams are separated into n said s-polarized beams and n said p-polarized beams. The method of claim 1, The third polarization beam includes an s-polarized beam and a p-polarized beam, And 2n second polarizing beams are separated into 2n s-polarized beams and 2n p-polarized beams. The method of claim 1, And the retardation plate is a quarter wave plate. The method of claim 1, And the retardation plate is a phase retardation plate. The method of claim 1, The first polarization layer and the second polarization layer is made of a material having the same refractive index, the thickness of the first polarization layer is characterized in that the beam nonuniformity reduction device, characterized in that twice the thickness of the second polarization layer. The method of claim 1, And wherein the first polarization layer and the second polarization layer comprise a birefringent medium. The method of claim 1, And an additional retardation plate for converting the incident beam into a circular polarization beam or an elliptical polarization beam.

Images