Prism assembly for separating light

This application is a continuation-in-part of commonly assigned U.S. patent application Ser. No. 11/013,868, filed Dec. 16, 2004, of which priority is hereby claimed.

Optical architectures of digital projectors typically include an illumination system, projection system, an optical modulator and one or more devices that couple the illumination system, projection system and the optical modulator. The illumination system illuminates the optical modulator. The optical modulator produces images by modulating the light falling across it by either reflecting or transmitting the light. The projection system images the optical modulator on the screen by capturing the modulated illumination of the optical modulator.

Generally, optical architectures have the optical axes of the projection and illumination paths either overlapping (across a portion of the system) or tilted substantially with respect to each other. For those systems that require or might benefit from a relatively on-axis or small incident angle illumination and projection paths on the optical modulator plane, such architectures may be inefficient, noisy, bulky or expensive. It would be desirable to be able to obtain high efficiency and low stray light in a compact package at a low cost in an optical architecture.

FIG. 1 is a block diagram illustrating an offset digital projection system according to one embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an offset digital projection system according to one embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating an offset digital projection system according to one embodiment of the present invention.

FIG. 4 is a flow chart illustrating a method for projecting an image using an offset digital projection system according to one embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a prism assembly according to one embodiment of the present invention.

FIG. 6 is a block diagram illustrating an on-axis digital projection system according to one embodiment of the present invention.

FIG. 7 is a schematic diagram illustrating a prism assembly according to one embodiment of the present invention.

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense.

As described herein, an optical architecture is provided for a digital projector that sets the optical axes of an illumination system and a projection system to be parallel and offset with respect to each other using coupling optics. The coupling optics allow the sharing of projection and illumination path spaces while maintaining the separation of the actual projection and illumination beams. By doing so, the architecture effectively separates the illumination and projection beam paths throughout the system.

In one embodiment, the coupling optics include a prism assembly. The prism assembly comprises a first prism component having a triangular cross-section along an optical path, a second prism component having a first quadrilateral cross-section along the optical path, a third prism component having a second quadrilateral cross-section along the optical path, a first dichroic interface between the first and second prism components and along the third prism component and configured to reflect a first range of wavelengths of the light, and a second dichroic interface between the first and third prism components and along the second prism component and configured to reflect a second range of wavelengths of the light.

FIG. 1 is a block diagram illustrating one embodiment of an offset digital projection system 10 . In projection system 10 , an illumination source 102 generates and emits an illumination beam to an illumination relay 106 along an optical path 104 . Illumination relay 106 integrates and collimates the illumination beam and provides the illumination beam to a coupling optics 110 along an illumination path 108 such that an optical axis of illumination path 108 is parallel or substantially parallel to a normal 100 to a plane 101 of a modulation device 114 . Normal 100 is substantially perpendicular to plane 101 , and plane 101 aligns with the modulating elements (not shown) of modulation device 114 . Coupling optics 110 directs and focuses the illumination beam onto modulation device 114 along an illumination path 112 . Illumination relay 106 images illumination source 102 onto modulation device 114 via coupling optics 110 such that modulation device 114 is uniformly illuminated with minimum overfill. Coupling optics 110 directs the illumination beam onto modulation device 114 at a non-zero angle of incidence. Coupling optics 110 are substantially centered with respect to modulation device 114 .

Modulation device 114 modulates the illumination beam from coupling optics 110 according to an input signal, e.g., a computer or video input signal, (not shown) to form an imaging beam. The imaging beam is reflected from modulation device 114 through coupling optics 110 along an optical path 116 . Coupling optics 110 directs the imaging beam from modulation device 114 through a projection lens 120 along a projection path 118 that an optical axis of projection path 118 is parallel or substantially parallel to normal 100 and the optical axis of illumination path 108 . Projection lens 120 focuses and may zoom the imaging beam along an optical path 122 to cause still or video images to be formed on a screen or other display surface. Projection lens 120 images modulation device 114 through coupling optics 110 onto the screen or other display surface used for final display.

In projection system 10 , illumination relay 106 , coupling optics 110 , and projection lens 120 are situated so as to minimize the overlap of the illumination and imaging beams along illumination path 108 and projection path 118 . In particular, the illumination beam and the imaging beam each intersect different areas of an optical pupil plane 124 of the system such that the imaging beam is spatially separated from the illumination beam at pupil plane 124 . Accordingly, illumination path 108 is effectively separated from projection path 118 . As shown in FIG. 1 , coupling optics 110 includes all optical elements between pupil plane 124 and modulation device 114 .

Illumination source 102 may be a mercury ultra high pressure, xenon, metal halide, or other suitable projector lamp that provides a monochromatic or polychromatic illumination beam. Modulation device 114 transmits or reflects selected portions of the illumination beam through coupling optics 110 and projection lens 120 in response to an image input signal (not shown) to cause images to be projected onto a screen or other surface. Modulation device 114 comprises at least one digital modulator such as a spatial light modulator like LCos, liquid crystal display (LCD), digital micromirror display (DMD) or other type. In one embodiment, modulation device 114 includes a separate digital modulator for each color, e.g., red, blue, and green.

Coupling optics 110 may include one or more color separation components such as the embodiment of prism assembly 500 shown in FIG. 5 or the embodiment of prism assembly 700 shown in FIG. 7 .

FIG. 2 is a schematic diagram illustrating one embodiment of an offset digital projection system 10 A. In projection system 10 A, illumination source 102 generates and emits an illumination beam 202 to an illumination relay 106 A along an optical path 104 . Illumination relay 106 A includes an integrating rod 200 that integrates illumination beam 202 and an illumination lens 204 that collimates illumination beam 202 and provides illumination beam 202 to a fold mirror 206 . Illumination lens 204 includes lenses 204 A, 204 B, and 204 C.

Fold mirror 206 reflects illumination beam 202 from illumination lens 204 through a coupling lens 110 A along an illumination path such that an optical axis of the illumination path of illumination beam 202 is parallel or substantially parallel to an optical axis of modulation device 114 between fold mirror 206 and coupling lens 110 A. In the embodiment shown in FIG. 2 , fold mirror 206 reflects illumination beam 202 at an angle of approximately ninety degrees between the optical axis of illumination lens 204 and the optical axis of coupling lens 110 A. In other embodiments, fold mirror 206 may be positioned differently to reflect illumination beam 202 at any non-zero angle between the optical axis of illumination lens 204 and the optical axis of coupling lens 110 A.

Coupling lens 110 A refracts and focuses illumination beam 202 onto modulation device 114 through a beamsplitter 210 . Beamsplitter 210 separates illumination beam 202 into separate components (e.g., red, blue, and green components) that are provided to different modulators 114 A, 114 B, and 114 C of modulation device 114 . Modulators 114 A, 114 B, and 114 C may be set in any suitable arrangement with respect to beamsplitter 210 . Beamsplitter 210 may be the embodiment of prism assembly 500 as shown in FIG. 5 or the embodiment of prism assembly 500 as shown in FIG. 7 . Beamsplitter 210 may be omitted in embodiments where modulation device 114 includes a single modulator. Coupling lens 110 A refracts illumination beam 202 onto modulation device 114 at a non-zero angle of incidence. Coupling lens 11 A, as shown, includes three lenses: 208 A, 208 B and 208 C to refract illumination beam 202 . In other embodiments, coupling lens 110 A may be a combination of one or more spherical or aspherical lenses.

Modulation device 114 modulates the illumination beam from coupling lens 110 A according to an input signal, e.g., a computer or video input signal, (not shown) to form an imaging beam 212 . Imaging beam 212 is reflected from modulation device 114 through beamsplitter 210 and into coupling lens 110 A. Coupling lens 110 A refracts imaging beam 212 from modulation device 114 through a projection lens 120 A using lenses 208 A, 208 B, and 208 C such that imaging beam 212 travels along an optical axis of a projection path that is parallel or substantially parallel to normal 100 to plane 101 of modulation device 114 and an optical axis of the illumination path of illumination beam 202 between coupling lens 110 A and an optical pupil plane 214 .

Projection lens 120 A focuses and may zoom imaging beam 212 along an optical path to cause still or video images to be formed on a screen or other display surface. Projection lens 120 A, as shown, includes four lenses: 216 A, 216 B, 216 C, and 216 D. In other embodiments, projection lens 120 A may be a combination of one or more spherical or aspherical lenses or mirrors.

In projection system 10 A, illumination relay 106 A, coupling lens 110 A, and projection lens 120 A are situated so as to minimize the overlap of illumination beam 202 and imaging beam 212 along the respective illumination and projection paths. In particular, the illumination beam and the imaging beam each intersect different areas of pupil plane 214 of the system such that imaging beam 212 is spatially separated from illumination beam 202 at pupil plane 214 . Accordingly, the illumination path is effectively separated from the projection path. As shown in FIG. 2 , coupling lens 110 A comprises all optical elements between pupil plane 214 and modulation device 114 .

FIG. 3 is a schematic diagram illustrating one embodiment of an offset digital projection system 10 B. In projection system 10 B, illumination source 102 generates and emits an illumination beam to illumination relay 106 along an optical path 104 . Illumination relay 106 integrates and collimates the illumination beam and provides the illumination beam to coupling lens 110 B along an illumination path 108 such that an optical axis of illumination path 108 is parallel or substantially parallel to normal 100 to plane 101 of modulation device 114 between illumination relay 106 and coupling lens 110 B.

Coupling lens 110 B refracts and focuses the illumination beam onto modulation device 114 through a beam splitter 304 . Beam splitter 304 separates the illumination beam into separate components (e.g., red, blue, and green components) that are provided to different modulators 114 A, 114 B, and 114 C of modulation device 114 . Modulators 114 A, 114 B, and 114 C may be set in any suitable arrangement with respect to beamsplitter 304 . Beamsplitter 304 may be an embodiment of prism assembly 500 as shown in FIG. 5 or an embodiment of prism assembly 500 as shown in FIG. 7 . Beamsplitter 304 may be omitted in embodiments where modulation device 114 includes a single modulator. Coupling lens 110 B refracts the illumination beam onto modulation device 114 at a non-zero angle of incidence as indicated by an optical path 112 . Coupling lens 110 B, as shown, includes three lenses: 302 A, 302 B and 302 C to refract the illumination beam. In other embodiments, coupling lens may be a combination of one or more spherical or aspherical lenses.

Modulation device 114 modulates the illumination beam from coupling lens 110 A according to an input signal, e.g., a computer or video input signal, (not shown) to form an imaging beam. The imaging beam is reflected from modulation device 114 along an optical path 116 through beamsplitter 304 and into coupling lens 110 B. Coupling lens 110 B refracts the imaging beam from modulation device 114 to a fold mirror 306 using lenses 302 A, 302 B, and 302 C such that the imaging beam travels along an optical axis of a projection path 118 that is parallel or substantially parallel to normal 100 to plane 101 of modulation device 114 and an optical axis of illumination path 108 of the illumination beam.

Fold mirror 306 reflects the imaging beam from coupling lens 110 B into projection lens 120 along an optical path 308 . In the embodiment shown in FIG. 3 , fold mirror 306 reflects the imaging beam at an angle of approximately ninety degrees between normal 100 and optical axis 308 of projection lens 120 . In other embodiments, fold mirror 306 may be positioned differently to reflect the imaging beam at any non-zero angle between normal 100 and optical axis 308 of projection lens 120 . Projection lens 120 focuses and may zoom the imaging beam from fold mirror 306 along optical path 122 to cause still or video images to be formed on a screen or other display surface.

In projection system 10 B, illumination relay 106 , coupling lens 110 B, and projection lens 120 are situated so as to minimize the overlap of the illumination and imaging beams along illumination path 108 and projection path 118 . In particular, the illumination beam and the imaging beam each intersect different areas of pupil plane 124 of the system such that the imaging beam is spatially separated from the illumination beam at pupil plane 124 . Accordingly, illumination path 108 is effectively separated from projection path 118 .

FIG. 4 is a flow chart illustrating one embodiment of a method for projecting an image using an offset projection system. In FIG. 4 , an illumination beam is provided from an illumination relay to coupling optics as indicated in a block 402 . The illumination beam is directed onto a modulation device using the coupling optics as indicated in a block 404 . The illumination beam is modulated to form an imaging beam using the modulation device as indicated in a block 406 . The imaging beam is directed parallel or substantially parallel to the illumination beam and a normal to the plane of the modulation device to a projection lens using the coupling optics as indicated in a block 408 . The imaging beam is focused and may be zoomed in or out using the projection lens as indicated in a block 410 .

In other embodiments, one or both of fold mirrors 206 and 306 may replaced with other reflective surfaces. In addition, a system may include fold mirrors in both the illumination and projection paths in other embodiments.

An offset optical architecture as described herein may effectively separate the illumination and projection paths while maintaining the optical performance and highest possible efficiency and minimizing stray light. This architecture may also avoid complex and expensive optical components and may allow for a compact package that has a maximum number of small sized lenses to achieve a low cost compact system.

FIG. 5 is a schematic diagram illustrating an embodiment of a prism assembly 500 from a top view. Prism assembly 500 may be used as part of coupling optics 110 in FIG. 1 and in place of beamsplitter 210 in FIG. 2 and beamsplitter 304 in FIG. 3 . Accordingly, prism assembly 500 separates light from the illumination paths and combines light from the projection paths in the embodiments of FIGS. 2 and 3 . In other embodiments, prism assembly 500 separates light from an illumination path and/or combines light from a projection path.

Prism assembly 500 includes prism components 502 , 506 , and 508 . Prism 502 includes faces 502 A, 502 B, and 502 C where faces 502 A, 502 B, and 502 C are arranged substantially orthogonal to the optical path of light 514 and form a triangular cross-section. Prism 506 includes faces 506 A, 506 B, 506 C, and 506 D where faces 506 A, 506 B, 506 C, and 506 D are arranged substantially orthogonal to the optical path of light 514 and form a quadrilateral cross-section. Prism 508 includes faces 508 A, 508 B, 508 C, and 508 D where faces 508 A, 508 B, 508 C, and 508 D are arranged substantially orthogonal to the optical path of light 514 and form a quadrilateral cross-section. Prism assembly 500 also includes a first dichroic interface 510 between faces 502 C and 508 B and along face 506 C and a second dichroic interface 512 between faces 502 B and 506 B and along face 508 C. Prism assembly 500 optionally operates in conjunction with a color wheel 516 as described in certain embodiments below.

In operation, prism assembly 500 receives light 514 from illumination relay 106 or 106 A through face 502 A and separates light 514 into two colors 514 A and 514 B. Each of the two colors corresponds to a mutually exclusive wavelength range of light such that each color may encompass one or more than one color range. For example, first color 514 A may encompass the range of wavelengths that include red, and second color 514 B may encompass the range of wavelengths that include green and blue. In FIG. 5 , colors 514 A and 514 B are shown schematically as being separate for illustration purposes. Light 514 passes through prism 502 onto first dichroic interface 510 and second dichroic interface 512 . First dichroic interface 510 transmits the second color 514 B, and second dichroic interface 512 transmits the first color 514 A.

First color 514 A reflects off of first dichroic interface 510 and totally internally reflects off of faces 502 A and 506 A onto modulator 114 A through face 506 D. More particularly, a first portion of first color 514 A reflects off of the portion of first dichroic interface 510 between faces 502 C and 508 B, totally internally reflects off of face 502 A, transmits through the portion of second dichroic interface 512 between faces 502 B and 506 B, and transmits through prism 506 onto modulator 114 A through face 506 D. A second portion of first color 514 A transmits through the portion of second dichroic interface 512 between faces 502 B and 506 B into prism 506 , reflects off of the portion of first dichroic interface 510 along face 506 C, and totally internally reflects off of face 506 A onto modulator 114 A through face 506 D.

Second color 514 B reflects off of second dichroic interface 512 and totally internally reflects off of face 502 A onto modulator 114 B through face 508 D. More particularly, a first portion of second color 514 B reflects off of the portion of second dichroic interface 512 between faces 502 B and 506 B, totally internally reflects off of face 502 A, transmits through the portion of first dichroic interface 510 between faces 502 C and 508 B, and transmits through prism 508 onto modulator 114 B through face 508 D. A second portion of second color 514 B transmits through the portion of first dichroic interface 510 between faces 502 C and 508 B into prism 508 , reflects off of the portion of second dichroic interface 512 along face 508 C, and totally internally reflects off of face 508 A onto modulator 114 B through face 508 D.

Modulators 114 A and 114 B modulate colors 514 A and 514 B, respectively, to selectively reflect light from colors 514 A and 514 B back through prism assembly 500 and along a projection path to form images as described above with reference to FIGS. 2 and 3 .

In one embodiment, modulator 114 B is configured to selectively, alternately reflect light for two different colors (i.e., two mutually exclusive subsets of the wavelength range of second color 514 B) of second color 514 B during different time periods. For example, second color 514 B may include blue and green light such that modulator 114 B reflects the green light during a first time period and modulator 114 B reflects the blue light during a second time period that is subsequent to the first time period.

In another embodiment, color wheel 516 is configured to alternately provide light for two different colors (i.e., two mutually exclusive wavelength ranges) of second color 514 B to modulator 114 B during different time periods. For example, second color 514 B may include blue and green light such that color wheel 516 provides the green light during a first time period to cause modulator 114 B to selectively reflect the green light and color wheel 516 provides the blue light during a second time period that is subsequent to the first time period to cause modulator 114 B to selectively reflect the blue light.

Angles α 1 and α 2 of prism 502 are set to provide a relatively shallow angle of incidence of first color 514 A on first dichroic interface 510 and a relatively shallow angle of incidence of second color 514 B on second dichroic interface 512 , respectively. Angles α 1 and α 2 of prism 502 are also set to ensure total internal reflection of colors 514 A and 514 B off of faces 502 A, 506 A, and 508 A as described above. In one embodiment, angles α 1 and α 2 are each set to approximately 30 degrees. In other embodiments, angles α 1 and α 2 are each set to other values.

Prism components 502 , 506 , and 508 are selected such that the path lengths of colors 514 A and 514 B between face 502 A and modulators 114 A and 114 B, respectively, are substantially equal. Prism components 502 , 506 , and 508 may also be selected such that the path lengths are as short as possible. In one embodiment prism components 502 , 506 , and 508 each comprise BK7 glass with an index of refraction of approximately 1.517. In other embodiments, prism components 502 , 506 , and 508 each comprise another type of glass with a different index of refraction.

In one embodiment, dichroic interfaces 510 and 512 each comprise a series of dielectric coatings applied to prism components 502 , 506 , and/or 508 . In other embodiments, dichroic interfaces 510 and 512 may be formed in other ways.

FIG. 6 is a block diagram illustrating an on-axis digital projection system 600 that includes prism assembly 500 . System 600 also includes a polarizing beamsplitter 602 , a retarder 604 , a set of illumination lenses 606 , a set of projection lenses 608 , and modulators 114 A and 114 B.

In operation, light 612 is polarized and reflected by polarizing beamsplitter 602 through retarder 604 and illumination lenses 606 into prism assembly 500 . Light 612 is selected reflected by modulators 114 A and 114 B back through prism assembly 500 , illumination lenses 606 , and retarder 604 to form an imaging beam. Retarder 604 rotates the polarization of the imaging beam and transmits the imaging beam through polarizing beamsplitter 602 and projection lenses 608 to form a projection beam 614 .

In other embodiments, retarder 604 may be replaced by retarders disposed between prism assembly 500 and modulators 114 A and 114 B. More particularly, a first retarder (not shown) may be disposed between face 506 D of prism component 506 and modulator 114 A and a second retarder (not shown) may be disposed between face 508 D of prism component 508 and modulator 114 B.

FIG. 7 is a schematic diagram illustrating an embodiment of a prism assembly 700 from a top view. Prism assembly 700 may be used as part of coupling optics 110 in FIG. 1 and in place of beamsplitter 210 in FIG. 2 and beamsplitter 304 in FIG. 3 . Accordingly, prism assembly 700 separates light from the illumination paths and combines light from the projection paths in the embodiments of FIGS. 2 and 3 . In other embodiments, prism assembly 700 separates light from an illumination path and/or combines light from a projection path.

Prism assembly 700 includes prism components 702 and 704 . Prism 702 includes faces 702 A, 702 B, and 702 C where faces 702 A, 702 B, and 702 C are arranged substantially orthogonal to the optical path of light 714 and form a triangular cross-section. Prism 704 includes faces 704 A, 704 B, 704 C, and 704 D where faces 704 A, 704 B, 704 C, and 704 D are arranged substantially orthogonal to the optical path of light 714 and form a quadrilateral cross-section. Prism assembly 700 optionally operates in conjunction with a color wheel 716 as described in certain embodiments below.

In operation, prism assembly 700 receives light 714 from illumination relay 106 or 106 A through face 702 A and separates light 714 into two colors (i.e., two mutually exclusive wavelength ranges) 714 A, and 714 B (e.g., red and green/blue, respectively). Light 714 passes through prism 702 onto dichroic interface 710 . Dichroic interface 710 reflects the first color 714 A and transmits the second color 714 B.

Color 714 A reflects off of dichroic interface 710 and totally internally reflects off of face 702 A onto modulator 114 A through face 702 B. Color 714 B transmits through dichroic interface 710 and of prism 704 onto modulator 14 B through face 704 C.

Modulators 114 A and 114 B modulate colors 714 A and 714 B, respectively, to selectively reflect light from colors 714 A and 714 B back through prism assembly 700 and along a projection path to form images as described above with reference to FIGS. 2 and 3 .

In one embodiment, modulator 114 B is configured to selectively, alternately reflect light for two different colors (i.e., two mutually exclusive subsets of the wavelength range of color 714 B) of color 714 B during different time periods. For example, color 714 B may include blue and green light such that modulator 114 B reflects the green light during a first time period and modulator 114 B reflects the blue light during a second time period that is subsequent to the first time period.

In another embodiment, color wheel 7 . 16 is configured to alternately provide light for two different colors (i.e., two mutually exclusive wavelength ranges) of color 714 B to modulator 114 B during different time periods. For example, color 714 B may include blue and green light such that color wheel 716 provides the green light during a first time period to cause modulator 114 B to selectively reflect the green light and color wheel 716 provides the blue light during a second time period that is subsequent to the first time period to cause modulator 114 B to selectively reflect the blue light.

Angle α 1 of prism 702 is set to provide a relatively shallow angle of incidence of color 714 A on dichroic interface 710 . Angle α 1 of prism 702 is also set to ensure total internal reflection of color 714 A off of faces 702 A as described above. In one embodiment, angle α 1 is set to approximately 30 degrees. In other embodiments, angle α 1 is set to other values.

Prism components 702 and 704 are selected such that the path lengths of colors 714 A and 714 B between face 702 A and modulators 114 A and 114 B, respectively, are substantially equal. Prism components 702 and 704 may also be selected such that the path lengths are as short as possible. In one embodiment prism components 702 and 704 each comprise BK7 glass with an index of refraction of approximately 1.517. In other embodiments, prism components 702 and 704 each comprise another type of glass with a different index of refraction.

In one embodiment, dichroic interface 710 comprises a series of dielectric coatings applied to prism components 702 and/or 704 . In other embodiments, dichroic interface 710 may be formed in other ways.

In other embodiments that incorporates prism assembly 500 or prism assembly 700 , modulators 114 A and 114 B each comprise a transmissive liquid crystal display (LCD). In one embodiment, colors 514 A and 514 B are selectively transmitted through modulators 114 A and 114 B, respectively, and into faces 506 D and 508 D, respectively, of prism assembly 500 . Prism assembly 500 combines the light from modulators 114 A and 114 B to transmit images through face 502 A of prism component 502 . In another embodiment, colors 714 A and 714 B are selectively transmitted through modulators 114 A and 114 B, respectively, and into faces 702 B and 704 C, respectively, of prism assembly 700 . Prism assembly 700 combines the light from modulators 114 A and 114 B to transmit images through face 702 A of prism component 702 .

Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Those with skill in the optical, mechanical, electro-mechanical, electrical, and computer arts will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the preferred embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.