JP2007505476A - Small efficient concentrator for scroll color illumination - Google Patents

Abstract

  The light source for the scroll color lighting system includes a lamp (212) that generates light, first and second independent reflectors (220, 230) that each receive a portion of the light from the lamp (212), and A light guide (260) for receiving two independent images of the light source produced by the portion of the light received by the first and second independent reflectors (220, 230). With such an arrangement, the light guide (260) provides at its output a light beam having an aspect ratio that is twice the aspect ratio of the light beam produced by the lamp (212), and Holds the original etendue of the light beam. Beneficially, the polarizing element (266) polarizes the unpolarized light beam from the light guide (260) without increasing the etendue, and in this process the aspect ratio is further doubled. .

Description

  The present invention relates to the field of light sources, and more particularly to a light concentrator for a scroll color illumination system that can be used with a single panel scroll color projection system.

  A scroll color projector (eg, a liquid crystal display panel) generates a full color image from a single light modulator or light valve. The general concept of scroll color projectors is discussed in US Pat. No. 5,532,763 by Janssen et al. (Hereinafter referred to as the “763 patent”), the entire disclosure of which is incorporated by reference. It is incorporated herein.

  As described in the aforementioned 763 patent, the scroll color projector uses a plurality of striped colored lights (red, green, blue) continuously scrolling from the top to the bottom on the liquid crystal display LCD. LCD) panel is illuminated. Light from an intense white light source (eg arc lamp) is collected and separated into primary colors (red, green and blue). Color separated light is formed into three light sources so that each source appears narrow in the “vertical” direction and wide in the “horizontal” direction. The scanning optics is used so that three light bands (one of each of the colors) are positioned on the LCD panel. By the scanning optical device, the band-like illumination is moved on the LCD panel. If the band passes the “top” of the active area of the panel, the light band of this color will reappear at the “bottom” of the panel. Thus, the three colors on the panel are swept continuously.

  FIG. 1 is a schematic diagram of illumination of an electro-optic light modulator panel in a scroll color system. Such panels are typically defined by individually addressable reflective pixel electrodes (not shown) that are addressed in a line-at-a-time manner. It is composed of a matrix of pixel rows (or lines) and columns. Red, blue and green rectangular colored light bars (32, 36, 40) continuously scroll down the matrix array (represented by squares 42) in the direction of the arrows. A red bar 32, blue bar 36 and green bar 40 are shown illuminating the panel at time t. The space between the colored bars 32, 36 and 40 represents the guard bars 30, 34 and 38.

  The system described in the 763 patent includes a light box that generates a source light beam. The light box includes a lamp of appropriate intensity. As described above and seen in FIG. 1, the light beam needs to be narrow in the “vertical” direction and wide in the “horizontal” direction. A typical system may require a rectangular light beam having a 10: 1 aspect ratio. On the other hand, the aspect ratio of a typical UHP arc lamp is 2.5: 1. Accordingly, the light box also includes a series of optical lenses that serve to deform the light beam, so that the light beam has the required shape of a generally uniform rectangular beam having the desired aspect ratio. Take. The system also includes one or more vertically arranged rectangular apertures to further rectangularize the light beam from the light box or three different colored light beams after color separation. Can do.

  Unfortunately, there are problems with these light sources. In order to collect the light generated by the lamp most, generally, (1) an approach that employs a large number of lenses with a small numerical aperture (NA) and (2) an approach that employs a small number of lenses with a high NA One of these is adopted. Both approaches suffer disadvantages. In the case of approach (1), the disadvantage relates to the complexity of a large number of lenses. In the approach (2), a high NA lens requires high heat resistance. Both approaches are costly.

  Accordingly, it would be desirable to provide an improved light source for a scroll color lighting system for a scroll color projector. It would also be desirable to provide a smaller optical arrangement that converts the light from the lamp into a light beam having a desired form factor. It is further desirable to provide an efficient light collection element for a scroll color lighting system. The present invention is directed to addressing one or more of the problems set forth above.

  In one aspect of the invention, the light source is positioned to receive a lamp that emits light; and to receive reflected light from the lamp and direct the received light in first and second directions, respectively. A pair of partial elliptical reflectors; first and second mirrors each positioned to receive and reflect light from one of said partial elliptical reflectors; disposed at its first end A light guide having two prisms, each prism having its second end in a light guide for inputting the reflected light from corresponding ones of the first and second mirrors into the ride guide. And a light guide for supplying a light beam at the section.

  In another aspect of the invention, the light source is first and second partial elliptical reflectors having first and second focal points, respectively, wherein the first focal points of the first and second partial elliptical reflectors are Said partially elliptical reflectors arranged to substantially coincide; lamps generally positioned at said first focal points of said first and second partial elliptical reflectors; and when said lamps are turned on; A light guide disposed at a location for receiving two independent images of light generated by the lamp via the partial elliptical reflector.

  In yet another aspect of the invention, the light source comprises: a lamp that generates light; first and second independent reflectors that each receive a portion of the light from the lamp; and the first and second independent A light guide for receiving two independent images of the light source produced by a portion of the light received by a reflector.

  FIG. 2 shows a side cross-sectional view of an embodiment of a light source 200 for a scroll color lighting system. FIG. 3 shows a front view of the light source 200. As shown in FIGS. 2 and 3, the light source 200 includes a lamp assembly 210 having a lamp 212 and a reflector 216; independent first and second partial elliptical reflectors 220 and 230; first and second mirrors. 240 and 250; light guide 260;

  Beneficially, the lamp 212 may be a high intensity discharge (HID) lamp or an ultra high performance (UHP) lamp, and is preferably tubular in shape. An exemplary lamp may be about 9 mm in length.

  Lamp reflector 216 beneficially has a hemispherical overall shape, or a semi-cylindrical overall shape, depending on the shape of lamp 212. Preferably, the lamp assembly 210 emits light toward only one side thereof, as will be described in detail later. The light from the lamp assembly 210 can be generally rectangular / elliptical. In an exemplary embodiment, the light generated by the lamp has an aspect ratio of 2.5: 1.

  As best seen in FIG. 4, the first and second partial elliptical reflectors 220 and 230, respectively, define an elliptical partial surface having first and second focal points. Beneficially, the first and second partial elliptical reflectors 220 and 230 are arranged such that the first focal points are generally coincident. Further, as can be seen in FIG. 2, the first and second partial elliptical reflectors 220 and 230 each have a cross section defining a portion of an elliptical arc. Equally beneficially, as can best be seen in FIG. 6, the first and second partial elliptical reflectors 220 and 230 share a common edge and together at this common edge. Are combined. In one embodiment, the first and second partial elliptical reflectors 220 and 230 are integrally formed together as shown in FIGS. 4-6.

  The light guide 260 includes first and second prisms 262 and 264 at the first (light entrance) end. The prisms 262 and 264 can be bonded to the first end of the light guide 260 by a low refractive index bonding agent, or can optionally be formed integrally with the light guide 260. The prisms 262 and 264 have corresponding light incident surfaces 262a and 264a, light reflecting surfaces 262b and 264b, and light emitting surfaces 262c and 264c. The reflective surfaces 262b, 264b are advantageously provided with a reflective or mirror coating.

  Similarly, as can best be seen in FIG. 5, the light guide 260 advantageously comprises a polarizing element 266 at the second (light exit) end. The polarization element 266 includes a polarization beam splitter 266a and a phase retarder 266b. The operation of the phase shifter 266b will be described in detail later. The beam splitter 266a can be bonded to the end of the light guide 260 by a low refractive index bonding agent, or can optionally be formed integrally with the light guide 260.

  Within the light source 200, the lamp assembly 210 is generally located at the first focus of the partially elliptical reflectors 220 and 230. On the other hand, the first and second mirrors 240 and 250 are respectively located in the optical path between the first and second partial elliptic reflectors 220 and 230 and their corresponding second focal points. Further, the light incident surfaces 262a, 264a of the prisms 262 and 264 are positioned, respectively, and arc images from corresponding ones of the first and second partial elliptical reflectors 220 and 230 are relayed by corresponding mirrors 240 and 250. Is done. That is, for example, the sum of the distance “x” between the first partial elliptic reflector 220 and the mirror 240 and the distance “y” between the mirror 240 and the incident surface 262a is the first partial elliptic reflector 220. Is equal to the focal length f2 of the second focal point.

  Here, the operation of the light source 200 will be described. The lamp 212 emits light. A first portion of light from the lamp 212 radiates toward the lamp reflector 216. The ramp reflector 216 reflects the first portion of light from the lamp 212 toward the first and second partial elliptical reflectors 220 and 230. On the other hand, the remaining light (second part) from the lamp 212 radiates directly toward the first and second partial elliptical reflectors 220 and 230. Beneficially, the lamp assembly 210 and the first and second partial elliptical reflectors 220 and 230 are such that substantially all of the light from the lamp assembly 210 is on the inner surfaces of the first and second partial elliptical reflectors 220 and 230. It is arranged to hit. That is, the first and second partial elliptical reflectors 220 and 230 each extend sufficiently far along a correspondingly defined ellipse to receive substantially all of the light from the lamp 212 and the lamp reflector 216. Exist.

  Advantageously, the lamp 212 is generally located at the first focal point of each of the first and second partial elliptical reflectors 220 and 230.

  The first and second partial elliptical reflectors 220 and 230 receive light from the lamp 212 (either directly or reflected by the lamp reflector 216) and are independently directed to their respective second focal points. Generate an arc image.

  The mirrors 240 and 250 are respectively located in the optical path between the corresponding ones of the first and second partial elliptical reflectors 220 and 230 and the second focal point of the corresponding partial elliptical reflector 220/230. Each of the mirrors 240 and 250 receives light from the corresponding partial elliptical reflector 220/230 and reflects the received light toward the corresponding one of the two prisms 262 and 264. The light incident surfaces 262a and 264a of the two prisms 262 and 264 are arranged at the positions of the images of the corresponding partial elliptic reflectors 220/230 so as to be relayed by the mirrors 240 and 250, respectively.

  The independent light image is incident on the prisms 262 and 264 via the light incident surfaces 262a and 264a, and is thereby passed to the corresponding light reflecting surfaces 262b and 264b. The light is reflected by the light reflecting surfaces 262b and 264b, and enters the first end portion of the light guide 260 via the light emitting surfaces 262c and 264c of the prisms 262 and 264. Thus, the two independent light images are longitudinally “end to end” adjacent to each other to produce a combined light beam having an aspect ratio twice that of the original light beam from lamp 212. end) ”is incident on the light guide. The light is internally guided by the light guide 260 and exits from the second end of the ride guide.

  The embodiment described above includes mirrors 240 and 250 and two prisms 262 and 264, but other means for receiving the independent light image and coupling the light image to light guide 260 are provided. Also good.

  Advantageously, as a result of the above-described process, the aspect ratio of the light beam produced by the lamp 212 is relatively small with little loss or efficiency without a corresponding increase in the etendue of the light beam. Is effectively doubled. For example, if the aspect ratio of the light beam from a typical UHP arc lamp is 2.5: 1, the aspect ratio of the light stripe emanating from the second end of the light guide 260 according to the system and process described above is 5: 1.

  For operation in a scroll color projector, the LCD panel requires linearly polarized light. However, the light beam from the lamp 212 is not polarized.

  Therefore, as described above, the ride guide 260 is advantageously provided with the polarizing element 266 at its second end, and the light beam is emitted from the polarizing element. As can best be seen in FIG. 6, the unpolarized light beam from light guide 260 is incident on polarizing beam splitter 266a. The portion of the light beam having the first (eg, horizontal) polarization passes through the polarization beam splitter 266a, while the remainder of the light beam having the second (eg, vertical) polarization is reflected by the phase shifter 266b. Is done. The phase of the light having the second (eg, vertical) polarization is rotated by 90 degrees by the phase shifter 266b, so that the polarization of the light having the second polarization passes through the polarization beam splitter 266a. Before being reflected along a path of light having (e.g., horizontal) polarization and a path that is adjacent and parallel, it is changed to the first (e.g., horizontal) polarization.

  Advantageously, as a result of the polarization process described above, the aspect ratio of the linearly polarized light beam emanating from the polarization element 266 is very small without a corresponding increase in the etendue of the light beam. With the loss of light or a decrease in efficiency, the aspect ratio of the unpolarized light beam incident on the polarizing element 266 is doubled. That is, the light beam that passes through the polarizing element 266 has an aspect ratio that is four times the aspect ratio of the light originally generated by the lamp 212.

  Thus, for example, if the aspect ratio of the light beam from a typical UHP arc lamp is 2.5: 1, the aspect ratio of the light stripe incident on the first end of the light guide 260 is 5: 1. The aspect ratio of the light stripe emitted from the polarizing element 266 at the second end of the light guide 260 is 10: 1.

  Thus, by providing two independent reflectors, each creating an independent image of the arc from the lamp, and combining the light of the two independent images, the etendue of the light beam can be maintained. At the same time, the beam aspect ratio can be adjusted without the cost and complexity associated with using a large number of small numerical aperture (NA) lenses or a small number of high NA lenses.

  The principles described in detail with respect to the embodiment shown in FIGS. 1 to 6 can be extended as follows. First, the image generated by the double reflector may be collected and combined in various ways other than through the folding mirrors 240, 250 and the corresponding prisms 262, 264 shown in FIGS. . For example, a “Y-shaped” light guide having two entrance surfaces positioned at the image points of the two independent reflectors can be used, and the combined light beam is the Y-shaped light The light exits from a single common exit surface of the guide. In this case, neither a mirror nor a prism is required.

  Furthermore, the double independent reflector may have a shape other than a partial ellipse. For example, a parabolic or spherical reflector can be used.

  FIG. 7 shows an alternative arrangement of a light source 700 that uses two independent parabolic reflectors 720, 730 instead of the partially elliptical reflectors 220 and 230 of FIGS. The light source 700 also includes magnifying lenses 725 and 735 that produce corresponding independent images of light from the lamp 710 reflected as two sets of parallel rays by independent parabolic reflectors 720 and 730. In the embodiment described, each of the magnifying lenses 725 and 735 has a magnifying factor “4”. Similarly, the light guide 760 is arranged such that the light guide 760 receives the two independent light images. The remaining structure and operation of the light source 700 are similar to the structure and operation of the light source 200 described above and are omitted here for the sake of brevity.

  The lamp reflector may also be omitted from the light source. In this case, some of the light from the lamp is lost, but such an arrangement is shown in FIGS. 1-6, where the lamp reflector can reflect a significant amount of heat back to the lamp. The life and reliability of the lamp can be improved compared to the case where it is used.

  Finally, the principle can be extended to produce etendue-retaining light beams with different aspect ratios. For example, instead of combining the light images in the “longitudinal direction”, the light images can be received adjacently to produce a more “square” shaped light beam while retaining the etendue of the original beam. Thus, the light guide can also be configured. Additionally or alternatively, the polarizing element at the second (outgoing) end of the light guide has an aspect ratio of the polarizing beam splitter and the polarized light beam to the polarizing element. It can also be constituted by a phase shifter that is directed to reduce the incident unpolarized light beam by half rather than twice.

  While preferred embodiments are described herein, many variations are possible which remain within the spirit and scope of the invention. Such modifications will become apparent to those of ordinary skill in the art after reading this specification, the accompanying drawings and the appended claims. Accordingly, the invention is not limited except as within the spirit and scope of the appended claims.

FIG. 3 shows a schematic diagram of illumination of an electro-optic light modulator panel in a scroll color system. FIG. 3 shows a schematic cross-sectional view of an embodiment of a light source for a scroll color illumination system. Fig. 3 shows a schematic front view of the light source for the scroll color illumination system of Fig. 2; FIG. 3 shows a side view of an embodiment of a light source for a scroll color lighting system. FIG. 5 shows a front view of an embodiment of a light source for the scroll color illumination system of FIG. 4. FIG. 5 shows a perspective view of an embodiment of a light source for the scroll color illumination system of FIG. 4. FIG. 4 shows a schematic cross-sectional view of another embodiment of a light source for a scroll color lighting system.

Claims (20)

A light source,
-A lamp that produces light;
-First and second partial elliptical reflectors, each of which is positioned to receive a portion of the light from the lamp and direct the received light in corresponding first and second directions; First and second partial elliptical reflectors, each producing an independent image of the light produced by the lamp;
-First and second mirrors each positioned to receive and reflect said light from one of said partially elliptical reflectors;
A light guide having two prisms arranged at its first end, each prism having a corresponding one of the independent images generated by the partial elliptical reflector in the light guide; An input light guide for supplying a light beam at its second end;
Having a light source.   A polarizing element disposed at the second end of the light guide, wherein the polarizing element receives the light beam at the second end of the light guide and converts the light beam into a polarized light beam. The light source of claim 1, further comprising: an aspect ratio of the polarized light beam that is twice an aspect ratio of the light beam received by the polarizing element.   The light source according to claim 2, wherein the polarizing element includes a polarizing beam splitter and a phase shifter.   The light source of claim 1, wherein the pair of partially elliptical reflectors are coupled together along their common edge. A light source,
First and second partial elliptical reflectors having first and second focal points respectively, the first and second partial elliptical reflectors being arranged such that the first focal points of the first and second partial elliptical reflectors are substantially coincident; A first and second partial elliptical reflector;
A lamp generally positioned at the first focus of the first and second partial elliptical reflectors;
A light guide disposed at a location where, when the lamp is turned on, two independent images of light generated by the lamp are received via the partial elliptical reflector;
Having a light source.   First and second mirrors disposed in an optical path between a corresponding one of the first and second partial elliptical reflectors and a second focal point of each of the first and second partial elliptical reflectors; The light source according to claim 5, further comprising:   The light source according to claim 5, further comprising first and second prisms disposed at an end portion of the light guide.   A lamp reflector arranged to reflect a portion of the light generated by the lamp toward the first and second partial elliptical reflectors when the lamp is turned on. Item 6. The light source according to Item 5.   The light source according to claim 5, further comprising a polarizing element disposed at the second end of the light guide.   The light source of claim 9, wherein the polarizing element further comprises a polarizing beam splitter and a phase shifter.   The light source according to claim 9, wherein the polarizing element doubles an aspect ratio of the light supplied at the second end of the light guide.   6. The light source of claim 5, wherein the first and second partial elliptical reflectors share a common edge. A light source,
-A lamp that produces light;
-First and second independent reflectors each receiving a part of the light from the lamp;
A light guide for receiving two independent images of the light source produced by a portion of the light received by the first and second independent reflectors;
Having a light source.   The light source of claim 13, wherein the first and second independent reflectors each have a partially elliptical shape.   14. The light source of claim 13, wherein the first and second independent reflectors each have a paraboloid shape.   16. The light source of claim 15, further comprising a pair of lenses that each receive reflected light from a corresponding one of the parabolic reflectors and make one of the images from the reflected light.   And a pair of mirrors each disposed in an optical path between a corresponding one of the lenses and an image of the lens, each of the mirrors directing light from the lens toward the light guide. The light source according to claim 16.   The light source of claim 13, wherein the light guide provides a light beam at its output, the light beam having an aspect ratio that is twice the aspect ratio of the light produced by the lamp.   The light source of claim 13, further comprising a pair of mirrors each receiving reflected light from a corresponding one of the independent reflectors and directing the reflected light toward the light guide.   A polarizing element disposed at a second end of the light guide, the polarizing element receiving the light beam at the second end of the light guide and converting the light beam into a linearly polarized light beam 14. The light source of claim 13, further comprising: an aspect ratio of the linearly polarized light beam being twice the aspect ratio of the light beam received by the polarizing element.

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