WO2000070874A1

WO2000070874A1 - Method and apparatus for an improved wide-angle display system

Info

Publication number: WO2000070874A1
Application number: PCT/US2000/011330
Authority: WO
Inventors: Robert D. Bordovsky; Richard B. Hughs; Amit Mehta; Neil M. Wheatley
Original assignee: Redifun Stimulation, Inc.
Priority date: 1999-05-12
Filing date: 2000-04-27
Publication date: 2000-11-23
Also published as: WO2000070874A8; EP1210820A2

Abstract

A wide-angle display system having an image projector, an image generator, and a plurality of CRT assemblies (200). Each CRT assembly includes a CRT member, an adapter housing (206), and a lens assembly. Each CRT member includes a CRT, a CRT cooling element (208), and a CRT housing for coupling to the image projector. The adapter housing has a first surface, and a second surface that forms a selected dihedral angle with the first surface. In an alternate embodiment, an adapter plate is disposed between the adapter housing and the lens assembly. The adapter plate has a first surface, and a second surface that forms the selected dihedral angle with the first surface. The selected dihedral angle between the adapter housing and the lens assembly causes a longitudinal axis of the CRT member to be offset from a longitudinal axis of the lens assembly, thereby correcting image distortion, such as Scheimpflug distortions.

Description

METHOD AND APPARATUS FOR AN IMPROVED WIDE-ANGLE DISPLAY

SYSTEM

Description

Technical Field

The present invention relates in general to wide-angle display systems and, in particular, to projection apparatus utilized in wide-angle collimated universal display systems.

Background Art

Wide-angle collimated universal display systems (hereinafter referred to as wide-angle display systems) are used in training systems as training simulators. These training simulators produce scenes that a viewer, or trainee, would observe if seated in an aircraft cockpit, a helicopter cockpit, a tank hatch, or other such vehicle location. Generally, the scene portrayed to the viewer is representative of "virtual" surroundings, such as terrain or airspace. For example, airlines, government agencies, and private training companies utilize wide-angle display systems in flight simulators used in pilot training programs.

Typical wide-angle display systems utilize large, bulky image projectors to create the virtual surrounding on panoramic display screens. These image projectors are difficult to install and calibrate, because they are designed to either remain in a fixed position, or have minimal movement. Such image projectors typically have three cathode ray tubes, or cathode ray tube assemblies (hereinafter CRT's), each with a corresponding lens. Usually, the three CRT's consist of a first CRT for generating red light, a second CRT for generating green light, and a third CRT for generating blue light. In most instances, the three CRT's are arranged in a triangular fashion with no regard for placement of to the CRT's, and each lens has a fixed focal length. Thus, to calibrate the image projector, or focus the image on the panoramic display screens, the entire image projector must be moved. These are laborious and time consuming processes, usually requiring a high degree of technical expertise.

In addition to the difficulties associated with installing and calibrating conventional wide-angle display systems, maintenance and repair are extremely time consuming and difficult. Because the CRT's and the corresponding lenses are permanently attached to each other, if a CRT or lens requires repair or replacement, the entire CRT and lens combination must be removed and sent to the manufacturer. In some cases, the entire image projector must be sent to the manufacturer. For these reasons, the owners of these conventional wide-angle display systems typically purchase and maintain backup image projectors in case of a failure of all or part of the primary image projector.

As one might expect, not only are repair and replacement of conventional wide-angle display systems difficult and time consuming, they are also very expensive. Replacement CRT and lens combinations for a typical wide-angle display system installed during the 1980 ' s at a cost of one million dollars or more, may cost hundreds of thousands of dollars.

Referring to Figure 6 in the drawings, a typical CRT and lens combination 300 for a prior-art wide-angle display system, similar to the system manufactured and sold by Hughes Display Products, Inc. under the product name SUPRALUX^®, is shown. CRT and lens combination 300 is one of three such CRT and lens combinations installed on such wide-angle display systems. The three CRT and lens combinations 300 are mounted to an image projector (not shown) in a triangular fashion, as explained above. CRT 301 is typically powered by a 36 Kilovolt power supply (not shown) that is coupled to CRT 301 at coupling 303. CRT 301 generates electron beams 302 that pass through focus coils 304. Focus coils 304 are coupled to a gimbal mounting assembly 305. Focus coils 304 align electron beams 302 prior to passage through a deflection coil 306. Deflection coil 306 is controlled by an image generator (not shown) for directing the electron beams 302 to a specific location on a reflective target 308.

As electron beams 302 impinge upon reflective target 308, electron beams 302 excite a phosphor coating 310. Excited phosphor coating 310 generates a particular color of light, usually red, green, or blue. The red, green, or blue light generated as electron beams 302 impinge upon phosphor coating 310 is reflected onto a reflective surface, or mirror, 312. Reflective surface 312 is typically a concave surface, such that the red, green, or blue light is reflected out of a front portion 313 of CRT 301. The red, green, or blue light then passes through a corrector lens 314 that is permanently fixed to CRT 301, usually at front portion 313. Corrector lens 314 redirects and focuses the red, green, or blue light onto a display screen (not shown) . Because corrector lens 314 is fixed to CRT 301, and because CRT and lens combination 300 are mounted at a fixed angle relative to the image projector, the focal length of CRT and lens combination 300 is fixed. Because corrector lens 313 is fixed to CRT 301, it is not possible to replace CRT 301 or corrector lens 314 independently with conventional, off- the-shelf (commercially available) replacement parts.

In addition, reflective target 308 is angled slightly relative to mirror 312 to correct Scheimpflug distortions that would result from projecting the image onto the curved and angled panoramic screens. Scheimpflug distortions occur when a lens is not oriented normal to a target. Because reflective target 308 has been slightly inclined or offset to correct Scheimflug distortions, CRT and lens combination 300 is considerably more expensive than conventional CRT's that do not make such corrections .

The only way to calibrate or alter the focal length of CRT and lens combinations 300 on such wide-angle display systems is to physically move either the entire image projector or all of the panoramic display screens until the projected image is in focus on the display screens. This is a complicated, laborious and time consuming process, usually requiring a high degree of technical expertise. As stated above, if reflective surface 312, phosphor coating 310, or corrector lens 314 require repair or replacement, CRT and lens combination 300 must be repaired or replaced in its entirety, which usually involves sending CRT and lens combination 300, or the entire image projector, back to the manufacturer.

Although the foregoing and other advances have been made with regard to wide-angle display systems, they have not adequately addressed the shortcomings in the art. For example, it would be desirable to have a CRT and lens combination apparatus that could be retrofitted into existing wide-angle display systems to replace existing CRT and lens combinations. It would also be desirable to have a wide-angle display system for which the CRT and lens could be repaired or replaced separately. Further, it would be desirable to have a wide-angle display system for which individual CRT and lens combinations could be calibrated and focused without having to move the entire image projector.

It would be desirable to have a wide-angle display system for which repair and replacement of components, such as CRT's and lenses, could be performed on-site. It would also be desirable to have a wide-angle display system for which individual components, such as CRTs and lenses, could be replaced by off-the- shelf replacement components. It would be further desirable to have a wide-angle display system that could be calibrated and focused by users without a high degree of technical expertise. It would be further desirable to have a wide-angle display system wherein the projected image is brighter and the life of each CRT is extended.

Disclosure of Invention

Advances in the art of wide-angle display systems have not overcome certain shortcomings and it is an object of the present invention to provide a CRT and lens combination apparatus that can be retrofitted into existing wide-angle projector systems to replace existing CRT and lens combinations.

It is another object of the present invention to provide a wide-angle display system having separate CRT and lens assemblies for which each CRT and each lens assembly can be repaired or replaced independently.

It is yet another object of the present invention to provide a wide-angle display system for which individual CRT and lens combinations can be calibrated and focused independently without having to move an entire image projector or all of the panoramic display screens.

It is yet another object of the present invention to provide a wide-angle display system for which repair and replacement of components, such as CRT's and lens assemblies, can be performed on-site.

It is yet another object of the present invention to provide a wide-angle projector system for which individual components, such as CRT's and lens assemblies, can be replaced by generic - 6 - replacement components.

It is yet another object of the present invention to provide a wide angle projector system that can be calibrated and focused by users without a high degree of technical expertise.

It is yet another object of the present invention to provide a wide-angle display system that will provide a brighter image and extend the life of the CRT's.

The foregoing objects are achieved by providing an improved wide-angle display system having three conventional high- definition, monochrome CRT members, or CRTs: a first CRT for generating red light, a second CRT for generating green light and a third CRT for generating blue light. Each CRT has an associated cooling element. The three CRT's are disposed in an equilateral triangular fashion on the face of the wide-angle projector. The green CRT is located at a top position and the red CRT and blue CRT located at bottom positions, thereby providing a clearer, better defined scene with improved edge blending. Each CRT is adapted to be installed into an image projector of either an existing wide-angle display system, or a wide-angle display system of original manufacture. Each CRT is coupled to a separate adapter housing. Each adapter housing is coupled to a separate adapter plate, each of which is configured to receive a conventional lens assembly for focusing the CRT.

In the preferred embodiment, each adapter housing is configured such that each corresponding lens assembly is oriented at a selected angle relative to the corresponding CRT and the other CRT's. In an alternate embodiment, this selective orientation is accomplished by a modified adapter plate that is configured such that each corresponding lens assembly is oriented at a selected angle relative to the corresponding CRT and the other CRT's. In this alternate embodiment, each adapter plate has a first mounting surface for attachment to the CRT, and a second mounting surface for attachment to the lens assembly. The selected angle is the dihedral angle between the first mounting surface and the second mounting surface of the adapter plate.

Orienting the lens assembly at the selected angle relative to the CRT eliminates the need for Scheimpflug calibrations. Each lens assembly includes dynamic and static lens adjustment controls to eliminate the need to physically move the image projector in order to calibrate or focus the projected image on the panoramic display screens.

The above, as well as, additional objectives, features, and advantages of the present invention will become apparent in the following detailed description when read in conjunction with the accompanying drawings .

Brief Description of Drawings

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:

Figure 1A is a top-view schematic of a wide-angle display system in which a preferred embodiment of the present invention may be implemented;

Figure IB is a left side view of the wide-angle display system of Figure 1A;

Figure IC is a front view of the wide-angle display system of Figure 1A;

Figure 2A is an exploded side view in partial cross-section of a CRT assembly of the wide-angle display system in accordance with a preferred embodiment of the present invention;

Figure 2B is a top view of the adapter housing for the CRT assembly of Figure 2A;

Figure 2C is a cross-sectional view of the adapter housing of Figure 2B taken at II -II;

Figure 2D is a perspective view of the adapter housing of Figure 2A;

Figure 2E is a top view of the adapter plate for the CRT assembly of Figure 2A;

Figure 2F is a side view of the adapter plate of Figure 2E;

Figure 3A is a side view in partial cross-section of an assembled CRT assembly of the wide-angle display system of the present invention according to an alternate embodiment;

Figure 3B an exploded side view in partial cross-section of the CRT assembly of Figure 3A;

Figure 3C is a front view of an adapter plate for the CRT assembly of Figures 3A and 3B;

Figure 4A is a schematic of a CRT connector/mounting printed circuit board (PCB) in accordance with a preferred embodiment of the present invention; Figure 4B is a schematic of a power supply circuit for the wide-angle display system according to the present invention;

Figure 5 is a perspective view of a wide-angle display system depicted in a airplane cockpit simulator application in accordance with a preferred embodiment of the present invention; and

Figure 6 is a side view of a prior-art CRT and lens combination.

Best Mode for Carrying Out the Invention

With reference now to the figures, and in particular, with reference to Figures 1A-1C, a preferred embodiment of a wide-angle display system 100 according to the present invention is depicted. In Figure 1A, wide-angle display system 100 is shown in a top-view schematic. Wide-angle display system 100 includes at least one image projector 102 and at least one panoramic display screen 104. It is not uncommon for a large installation to include a plurality of image projectors 102 generating images on a plurality of panoramic display screens 104. An example of such a large installation would be one for a flight simulator for a large commercial aircraft (see Figure 5) . When using multiple image projectors 102, it is necessary that image projectors 102 be calibrated. Calibrating is a process whereby multiple displayed images are adjusted so that the displayed images appear on the panoramic display screens as an uninterrupted, continuous scene.

Image projector 102 houses a plurality of, preferably three, CRT assemblies 106, 108, and 110. CRT assemblies 106, 108, and

110 are also represented by reference letters R for red, G for green, and B for blue, respectively. As is shown in Figures 1A and IB, it may be necessary for CRT assemblies 106, 108, and 110 to protrude out from a front surface 101 of image projector 102. Image projector 102 includes a housing, a conventional power source (not shown) , electronic circuits and assemblies for controlling and generating images (see Figures 4A and 4B) , and three monochrome CRT members operably associated with three lens assemblies (see Figures 2A, 3A, and 3B) . CRT assembly 106 generates green light; CRT assembly 108 generates red light; and CRT assembly 110 generates blue light. As is shown in Figure IC, CRT assemblies 106, 108, and 110 are preferably arranged in an equilateral triangular shape, with CRT assembly 106 at the top position, and CRT assemblies 108 and 110 at the base positions. The significance of such an arrangement will be explained in detail below.

Each CRT assembly 106, 108, and 110, is adapted to generate images over a predetermined range, as indicated by the dashed lines in Figure 1A. CRT assembly 106 has an image range 106a, CRT assembly 108 has an image range 108a, and CRT assembly 110 has an image range 110a. Each CRT assembly 106, 108, and 110 has a projection center line 106b, 108b, and 110b, respectively. Projection center lines 106b, 108b, and 110b intersect at a focal point 111, preferably located on panoramic display screen 104. It should be understood that Figure 1A is not drawn to scale, and that, in reality, center lines 106b, 108b, and 110b are nearly parallel . Focal point 111 is generally defined by the distance from front surface 101 to panoramic screen display 104. It is preferred that focal point 111 be in the range of about 110 to 122 inches. As will be explained below, the present invention allows for minor adjustments to focal point 111 to be made quickly and easily.

In conventional wide-angle display systems, blue CRT assembly 110 is located in the top position of the triangular arrangement . However, according to the present invention, green CRT assembly 106 is located in the top position of the triangular arrangement. Significant advantages are achieved by locating green CRT assembly 106 in the top position. Image projector 102 is usually located directly above the user. By locating green CRT assembly in the top center position, the brightest light of the wide-angle display system is along the same axis as the user's line of sight. This means increased overall brightness to the user, and a clearer, better-defined image display. In addition, by always placing green CRT assembly 106 in the top center location, particularly with installations having multiple image projectors 102, there is less brightness variation across the field of view; and soft edge blanking. Soft edge blanking, the process of blending the border resulting between adjacent images projected by each projector in the simulator, is improved greatly, thereby providing the appearance of more uniform edge blending between adjacent images.

Because green CRT assembly 106 supplies the majority of the brightness of image projector 102, green CRT assembly usually requires replacement more often. Another advantage of placing green CRT assembly 106 in the top position is that maintenance and replacement are easier.

Referring now to Figures 2A-2F in the drawings, a CRT assembly 150 according to the preferred embodiment of the present invention is illustrated. In Figure 2A, CRT assembly 150 is illustrated in an exploded view in partial cross-section. CRT assembly 150 is representative of CRT assemblies 106, 108, and 110. CRT assembly 150 includes a conventional CRT housing 152, conventional CRT 154 having a conventional cooling element 156, adapter housing 158 coupled to CRT housing 152, adapter plate 160 coupled to adapter housing 158, and conventional adjustable lens assembly 162 coupled to adapter plate 160. CRT 154 and cooling element 156 generally define a "CRT member, " which, for purposes of the present invention, may be used interchangeably with the phrase "CRT." CRT 154 is preferably a 9-inch high-definition monochrome color projection tube having an attached cooling element 156, similar to the CRT manufactured and sold by the Sony Corporation under model number 09MEX2. When assembled, CRT housing 152, CRT 154, and adapter housing 158 share a common longitudinal CRT axis 164. CRT 154 is connected to power and electronics (not shown) via conventional cables and connectors (not shown) .

CRT housing 152 is adapted to be releasably coupled to front surface 101 of image projector 102 (see Figures 1A-1C) by conventional fastening means (not shown) , preferably by the provision of a plurality of mounting apertures 166. CRT housing 152 may be integral with front surface 101 of image projector 102. CRT 154 is adapted to utilize the electronics and electrical connectors from existing image projectors. Thus, CRT housing 152 and CRT 154 may be components of image projector 102 as originally manufactured, or may be retrofitted into an existing image projector. Such retrofitting will be discussed in more detail below. Adapter housing 158 is releasably coupled to CRT housing 152 by conventional fastening means (not shown) , preferably by the provision of a plurality of mounting apertures 168 that pass longitudinally through a plurality of radially extending flange members 169. Mounting apertures 168 align with a plurality of mounting apertures 173 in CRT housing 152. As seen in Figure 2D, flange members 169 include recessed portions 169a that allow access to mounting apertures 166.

Adapter housing 158 has a flat rear surface 171 and a plurality of opposing integral protrusions 172 that extend longitudinally away from flat rear surface 171. Protrusions 172 terminate in flat surfaces 174. Protrusions 172 provide recessed, open areas 172a that allow clearance of CRT 154. Flat surfaces 174 define a plane that forms a dihedral angle cc with rear surface 171. Dihedral angle oc is preferably about 1° and may be in the range of 0.75° to 1.75° depending on the mounting arrangement. Each flat surface 174 includes at least one longitudinal mounting aperture 175. Mounting apertures 175 are not parallel with CRT axis 164; rather, mounting apertures 175 are offset from CRT axis 164 by angle α. As explained above, when a lens is not pointed normal to a target, a distortion condition called the Scheimpflug distortion is created. Angle α substantially eliminates any Scheimpflug distortion present as a result of projecting images onto panoramic display screens 104.

Referring particularly to Figures 2B, 2C, and 2D in the drawings, adapter housing 158 includes a plurality of flange members 177 that extend radially outward from adapter housing 158.

Flange members 177 are generally parallel to rear surface 171; therefore, flat surfaces 174 also form dihedral angle a with flange members 177, and consequently, CRT 154. Flange members 177 are preferably located in the recessed, open areas 172a of protrusions 172. Flange members 177 include mounting apertures

179 so that CRT 154 may be releasably coupled to and carried by adapter housing 158.

Adapter plate 160 is releasably coupled flushly against flat surfaces 174 of adapter housing 158 by a plurality of conventional fastening means (not shown) that pass through a plurality of apertures 170 in adapter plate 160. As such, adapter plate 160 forms dihedral angle α with rear surface 171 of adapter housing 158.

Adapter plate 160, is preferably an annular ring having a front surface 176 and an opposing parallel rear surface 178. In Figure 2A, adapter plate 160 is shown in a cross-sectional view taken at III-III of Figure 2E. A circular aperture 180 passes concentrically through the center of adapter plate 160. It should be understood that adapter housing 158 and adapter plate 160 may be integrated into a single component.

Lens assembly 162 includes a plurality of lenses, such as lens 182, and is preferably similar to the lens assembly manufactured and sold by U.S. Precision Lens under the model name Condor. Lens assembly 162 includes a static focus adjustment 184 for focusing interior portions of the displayed image on panoramic display screen 104, and a dynamic focus adjustment 186 for focusing perimeter portions of the displayed image on panoramic display screens 104. Lens assembly 162 includes a mounting flange 188 having a plurality of mounting apertures 190.

Lens assembly 162 is releasably coupled flush against adapter plate 160 by conventional fastening means (not shown) that pass through mounting apertures 190 in mounting flange 188 and a plurality of aligned mounting apertures 192 (see Figure 2E) that pass through adapter plate 160. As mentioned above, mounting apertures 170 in adapter- plate 160 are aligned with mounting apertures 175 in flat surfaces 174 of adapter housing 158. In this manner, lens assembly 162 is offset from rear surface 171 of adapter housing 158 by dihedral angle oc.

Lens assembly 162 has a longitudinal lens axis 192. When installed, rear surface 178 of adapter plate 160 flushly contacts flat surfaces 174 of adapter housing 158; and mounting flange 188 of lens assembly 162 flushly contacts front surface 176 of adapter plate 160. Thus, when CRT assembly 150 is assembled, lens axis 192 and CRT axis 164 are not parallel; rather, CRT axis 164 and lens axis 192 are offset by angle α, such that lens assembly 162 angles inwardly toward the center of front surface 101 of image projector 102. Focal point 111 is created at the intersection of the lens axis 192 of each lens assembly 215 of CRT assemblies 106, 108, and 110 of image projector 102. Focal point 111, though set by angle a of adapter housing 158, may be further adjusted utilizing static focus adjustment 184 and dynamic focus adjustment 186.

Adapter housing 158 and adapter plate 160 allow the unique combination of conventional CRT 154 and conventional CRT housing 152 with conventional lens assembly 162. Using this unique combination, off-the-shelf components can be used in a retrofit application on existing image projectors, thus greatly reducing the cost of repair and replacement of CRT assemblies, such as prior-art CRT assembly 300 (see Figure 6) . The present invention corrects Scheimpflug distortions without the need for an expensive CRT having a reflective target 308 that must be angled slightly relative to a mirror 312 (see Figure 6) as is employed in the prior art .

Prior-art wide-angle display systems have a focal point located about 112 inches from the panoramic display screens. Focal length 111 for the present invention is preferably about 115 inches. As such, minor modifications to mounting assemblies (not shown) of image projector 102 may be necessary during initial installations when the present invention is used in a retrofit application. However, fine tuning of focal length 111 may be accomplished utilizing static focus adjustment 184 and dynamic focus adjustment 186.

Referring now to Figures 3A-3C in the drawings, a CRT assembly 200 according to an alternate embodiment of the present invention is illustrated. CRT assembly 200 is representative of CRT assemblies 106, 108, and 110. As best seen in Figure 3B, CRT assembly 200 includes a conventional CRT housing 202, a conventional CRT 204 having a conventional cooling element 208, an adapter housing 206 coupled to CRT housing 202, an adapter plate 210 coupled to adapter housing 206, and a conventional adjustable lens assembly 215 coupled to adapter plate 210. CRT 204 and cooling element 208 generally define a CRT member. As in the preferred embodiment, CRT 204 is preferably a 9-inch high- definition monochrome color projection tube having an attached liquid coupled cooling element 208, similar to the CRT manufactured and sold by the Sony Corporation under model number 09MEX2. CRT housing 202, CRT 204, adapter housing 206, and adapter plate have a common longitudinal CRT axis 216. CRT 204 is connected to power and electronics (not shown) via appropriate cables and connectors (not shown) . CRT 204 is adapted to utilize the electronics and electrical connectors from existing image projectors .

CRT housing 202 is adapted to be releasably coupled to front surface 101 of image projector 102 (see Figures 1A-1C) by conventional fastening means (not shown) , preferably by the provision of aligned apertures 211. CRT housing 202 may be integral with front surface 101 of image projector 102. Thus, CRT housing 202 may be a component of image projector 102 as originally manufactured, or may be retrofitted into an existing image projector. Such retrofitting will be discussed in more detail below. Adapter housing 206 is releasably coupled to CRT housing 202 by conventional fastening means (not shown) , preferably by the provision of a plurality of mounting apertures 213 that pass longitudinally through a plurality of radially extending flange members 213a. Mounting apertures 213 align with a plurality of mounting apertures 202a in CRT housing 202. As seen in Figure 3B, flange members 213a include recessed portions 206a that allow access to mounting apertures 202a.

Adapter plate 210 is releasably coupled to adapter housing 206 by a plurality of fastener means, preferably screws 210a that pass through a plurality of mounting apertures 207 in adapter plate 210 and through aligned apertures 206c that pass through inwardly extending flanges 206d located at the end of adapter housing 206. Screws 210a are matingly received by a plurality of spacing fasteners 209 having a threaded male end 209a, a head 209b, and internal female threads 209c inset within head 209b. Female threads 209c of spacing fasteners 209 matingly receive screws 210a. In this manner, adapter plate 210 is flushly mounted against flange 206d of adapter housing 206. Screws 210a, spacing fasteners 209, and mounting apertures 213 are parallel to CRT axis 216.

Threaded male ends 209a extend through mounting apertures 204a in CRT 204 and are secured by nuts 204b. In this manner, CRT 204 and cooling element 208 are releasably coupled to adapter plate 210. Thus, CRT 204 is not directly coupled to adapter housing 206. Spacing fasteners 209 maintain a selected clearance between CRT 204 and adapter plate 210. A plurality of longitudinal cut-outs 206b in adapter housing 206 provide clearance for screws 210a, spacing fasteners 209, and the corners of CRT 204.

Adapter plate 210 has a generally square-shaped rear surface 240, and a generally octagonal -shaped front surface 242. Rear surface 240 and front surface 242 are preferably parallel to each other. A generally octagonal -shaped recessed portion 244 extends inward from front surface 242, and a longitudinal circular aperture 246 passes through adapter plate 210. Aperture 246 is smaller in diameter than recessed portion 244 such that a flange 248 extends radially inward around adapter plate 210. Recessed portion 244 and flange 248 are created by precision grinding such that a front machined surface 217 exists. Front machined surface 217 forms a predetermined dihedral angle α with rear surface 240. Angle α is preferably about 1°.

Lens assembly 215 includes a plurality of lenses, such as lens 225, and is preferably similar to the lens assembly manufactured and sold by U.S. Precision Lens under model name Condor. Lens assembly 215 includes a static focus adjustment 212 for focusing interior portions of the displayed image on panoramic display screen 104, and a dynamic focus adjustment 214 for focusing perimeter portions of the displayed image on panoramic display screens 104. Lens assembly 215 includes a mounting flange 219 having mounting apertures 219a. Recessed portion 244 is octagonally shaped to accommodate mounting flange 219 of lens assembly 215. It should be understood that recessed portion 244 may be of different shapes depending upon the shape of mounting flange 219 of lens assembly 215.

Lens assembly 215 is coupled to adapter housing 206 via adapter plate 210. In Figure 3B, adapter plate 210 is shown in cross-section along section lines B-B of Figure 3C. Lens assembly 215 is releasably coupled to adapter plate 210 by conventional fasteners (not shown) that pass through mounting apertures 219a and apertures 243 that pass through flange 248 in adapter plate 210. Apertures 243 in flange 248 are perpendicular to front machined surface 217. Thus, apertures 243 are offset by angle α from CRT axis 216. In this manner, lens assembly 215 is offset from CRT housing 202, CRT 204, and adapter housing 206 by angle ex.

Lens assembly 215 has a longitudinal lens axis 226. When installed, rear surface 240 flushly contacts adapter housing 206, as shown in Figure 3A. Also, when installed, mounting flange 219 of lens assembly 215 flushly contacts front machined surface 217. Thus, when CRT assembly 200 is assembled, as shown in Figure 3A, lens axis 226 and CRT axis 216 are not parallel; rather, CRT axis 216 and lens axis 226 form angle α such that lens assembly 215 angles inwardly toward the center of front surface 101 of image projector 102. It is preferable that CRT axis 216 and lens axis 226 intersect at a point of intersection 230 located between a front surface 232 of CRT 204 and a rear surface 234 of lens assembly 215. Focal point 111 is created at the intersection of the lens axes 226 of each lens assembly 215 of the three CRT assemblies 106, 108, and 110 of image projector 102.

Angle substantially eliminates any Scheimpflug distortion present as a result of projecting images onto panoramic display screens 104. Focal point 111, though set by angle α of adapter plate 210, may be further adjusted utilizing static focus adjustment 212 and dynamic focus adjustment 214.

Adapter housing 206 and adapter plate 210 allow the unique combination of conventional CRT 204 and conventional CRT housing 202 with conventional lens assembly 215. Using this unique combination, off-the-shelf components can be used in a retrofit application on existing image projectors, thus greatly reducing the cost of repair and replacement of CRT assemblies, such as prior-art CRT assembly 300 (see Figure 6) . It should be understood that adapter housing 206, adapter plate 210, and front machined surface 217 may be integrated into a single component.

Prior-art wide-angle display systems have a focal point located about 112 inches from the panoramic display screens. Focal point 111 for the present invention is preferably in the range of about 110 to 122 inches. As such, minor modifications to mounting assemblies (not shown) of image projector 102 may be necessary during initial installations when the present invention is used in a retrofit application. However, fine tuning of focal length 111 may be accomplished utilizing static focus adjustment 212 and dynamic focus adjustment 214.

Referring now to Figure 4A in the drawings, a schematic of a connector/mounting printed circuit board (PCB) 400 for CRT 154 or CRT 204 according to the present invention is illustrated. Connector/mounting PCB 400 is adapted to replace existing connector/mounting PCB ' s in retrofit applications. In connector/mounting PCB 400, the connector (not shown) for CRT 204 is mounted directly on connector/mounting PCB 400, thereby providing a quick and easy connection to the existing CRT support assembly (not shown) . By using connector/mounting PCB 400, all electrical and most mechanical connections from an existing image projector to CRT assemblies 106, 108, and 110 require little or no additional modification.

Referring now to Figure 4B in the drawings, a schematic of a power supply circuit 410 for the wide-angle display system 100 of the present invention is illustrated. Power supply circuit 410 is utilized in a retrofit application. As such, an existing power supply 412, usually a 36 Kilovolt power supply, is controlled by existing controls and connectors 414. In a preferred embodiment, existing power supply 412 is adjusted, utilizing a high voltage potentiometer integral to existing power supply 412, so that voltage available at CRT assemblies 106, 108, 110 is 32KV.

In another, less desirable embodiment, at least one dropping resistor and connector interchange unit (not shown) is electrically coupled between power supply 412 and each CRT assembly 106, 108, and 110. Dropping resistor and connector interchange unit (not shown) can reduce the voltage to CRT assemblies 106, 108, and 110 to about 32 Kilovolts. In this manner, existing power supply 412 in an existing image projector does not have to be replaced or adjusted to allow CRT assemblies 106, 108, and 110 to be retrofitted into the existing image projector.

Referring now to Figure 5 in the drawings, a perspective view of a wide-angle display system 500 according to the present invention is illustrated being used in an airplane cockpit simulator application. An image projector 502, similar to image projector 102, is shown installed directly above and behind pilot's consoles 503. It would not be uncommon in such an application to have a plurality of image projectors 502. Image projector 502 projects synchronized images onto panoramic display screens 504. It should be apparent wide-angle display system 500 could be easily modified for use in a helicopter cockpit simulator application by modifying the size and placement of panoramic display screens 504 and changing the arrangement of pilot's consoles 503.

In its retrofit application, the wide-angle display system 100 of the present invention functions without any change in the calibration procedures of the existing image projector. No additional changes are necessary for correction of distortion. Existing power supplies do not need to be replaced, and there is no need for image generator calibration. Consequently, modifications to the image projector may be made in the field. Because improved CRT assemblies 106, 108, and 110 are used, the time from power off to a training picture is shortened and CRT life expectancy is nearly doubled.

Although the present invention describes correction of image distortions by employing a selected dihedral α between surfaces of either adapter housing 158 or adapter plate 210, it should be understood that dihedral angle α may also be integrated into lens assembly 162 or 215. In addition, it should be understood that the use of surfaces forming selected dihedral angle α is only one of several means of correcting image distortions. Other means of correcting image distortions include incorporating one or more inserts, washers, and spacers to offset a lens assembly from a CRT assembly.

The wide-angle display system of the present invention provides a significant improvement in convergence and color balance stability over the prior-art systems. By positioning the green CRT assembly 106 in the top position, improved brightness of the displayed image is provided. In addition, this arrangement provides improved definition of the displayed image, a reduced need for green CRT brightness, and easier access to green CRT assembly 106. The inherently brighter green CRT projected image provides a reduction in intensity which lengthens the life of green CRT assembly 106.

A further advantage of the wide-angle display system of the present invention is that the cost of maintaining and replacing CRT and lens elements is greatly reduced. In addition, maintenance and calibration time for image projector 102 is reduced. CRT assemblies 106, 108, and 110 substitute directly for existing CRT and lens assemblies in existing image projectors, and provide better edge match, improved contrast ratio, and improved light-point profile.

While the invention has been particularly shown and described with reference to a preferred embodiment, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. A wide-angle display system comprising: an image projector for projecting an image onto a panoramic display screen; a plurality of adapter housings, each adapter housing having a front surface and a rear surface, said front surface and said rear surface being configured to form a selected dihedral angle, each said rear surface being flushly coupled to said image projector; a plurality of CRT members, each CRT member being coupled to a corresponding said adapter housing; a plurality of lens assemblies, each lens assembly being coupled to a corresponding said front surface; and at least one image generator for controlling said CRT members.

2. The wide-angle display system according to claim 1, wherein said plurality of CRT members comprises: a high-intensity monochrome green CRT member; a high-intensity monochrome red CRT member; and a high-intensity monochrome blue CRT member.

3. The wide-angle display system according to claim 2, wherein said high-intensity monochrome green CRT member is located above said high- intensity monochrome red CRT member and said high- intensity monochrome blue CRT member.

4. The wide-angle display system according to claim 2, wherein said plurality of coupled adapter housings form an equilateral triangle with said high-intensity monochrome green CRT member being disposed in a top position, and said high- intensity monochrome red CRT member and said high-intensity monochrome blue CRT member each being disposed in a bottom position.

5. The wide-angle display system according to claim 1, wherein each said CRT member comprises: a CRT housing; a high-intensity monochrome CRT carried by said CRT housing; and a cooling element.

6. The wide-angle display system according to claim 1, wherein said selected dihedral angle is within a range of 0.75° to 1.75°.

7. The wide-angle display system according to claim 6, wherein said dihedral angle is appropriate for correcting any Scheimpflug image distortions.

8. The wide-angle display system according to claim 1, wherein said lens assembly comprises : at least one lens; at least one static focus adjustment; and at least one dynamic focus adjustment.

9. The wide-angle display system according to claim 1, further comprising: an adapter plate being disposed between each said adapter housing and each said corresponding lens assembly.

10. A method for displaying a wide-angle image on at least one panoramic display screen, the method comprising the steps of: providing an image projector for projecting said wide-angle image ; coupling a plurality of CRT members to said image projector; disposing an adapter plate between each said CRT member and a corresponding lens assembly; utilizing said adapter plate for inducing said CRT member and said corresponding lens assembly to form a selected dihedral angle with a centerline of said CRT member in the range of 0.75° to 1.75°; and adjusting voltage to each said CRT member.

11. The method according to claim 10, wherein the step of coupling a plurality of CRT members to said image projector further comprises: coupling a high-intensity monochrome green CRT member to said image projector; coupling a high- intensity monochrome red CRT member to said image projector; and coupling a high- intensity monochrome blue CRT member to said image projector adjusting said voltage to each said CRT Member to 32 kilovolts.

12. The method according to claim 11, wherein said high-intensity monochrome green CRT member is coupled to said image projector in a superior position above said high- intensity monochrome red CRT member and said high-intensity monochrome blue CRT member.

13. The method according to claim 11, further comprising: providing a plurality of CRT housings; coupling a high-intensity monochrome CRT to each said CRT housing; and coupling an adapter housing to each said CRT housing.

14. The method according to claim 11, further comprising: forming a selected angle between a longitudinal axis of each said lens assembly and a longitudinal axis of each corresponding said CRT member.

15. The method according to claim 14, wherein said selected angle is within a range of 0.75° to 1°.

16. An apparatus for retrofitting into an existing wide-angle display system having an existing power supply, existing control circuitry, at least one existing image projector for projecting an image onto at least one existing wide angle display screen wherein said image projector comprises at least one existing CRT member and an existing lens assembly coupled to said at least one existing CRT member, further comprising: at least one replacement CRT assembly adapted to replace said existing CRT member and said existing lens assembly; and instructions for adjusting voltage to each said CRT member.

17. The apparatus according to claim 16, wherein said at least one replacement CRT assembly comprises: a replacement CRT housing; a replacement CRT member coupled to said replacement CRT housing, said replacement CRT member being adapted to be controlled by said at least one existing image generator; an adapter housing coupled to said replacement CRT housing; and a replacement lens assembly coupled to said adapter housing.

18. The apparatus according to claim 17, wherein a selected angle is formed between said adapter housing and said lens assembly.

19. The apparatus according to claim 18, wherein the selected angle is within a range of 0.75° to 1.75°.

20. The apparatus according to claim 17, further comprising: replacement voltage control circuitry configured to replace said existing voltage control circuitry.

21. The apparatus according to claim 20, wherein said replacement control circuitry comprises: at least one dropping resistor and connector interchange unit for adjusting an existing power output from said existing power supply to match a power requirement for said replacement CRT member .

22. The apparatus according to claim 21, wherein said at least one dropping resistor and connector interchange unit changes said existing power output to 32 kilovolts.

23. A wide-angle display system comprising: an image projector for projecting an image onto a panoramic display screen; a plurality of adapter housings coupled to said image projector; a plurality of adapter plates, each adapter plate having a front surface and a rear surface, said front surface and said rear surface being configured to form a selected dihedral angle, each said rear surface being flushly coupled to a corresponding said adapter housing; a plurality of lens assemblies, each lens assembly being coupled to a corresponding said front surface; a plurality of CRT members, each CRT member being coupled to a corresponding said adapter plate; and at least one image generator for controlling said CRT members.

24. The wide-angle display system according to claim 23, wherein said plurality of CRT members comprises: a high-intensity monochrome green CRT member; a high-intensity monochrome red CRT member; and a high-intensity monochrome blue CRT member.

25. The wide-angle display system according to claim 24, wherein said high-intensity monochrome green CRT member is located above said high-intensity monochrome red CRT member and said high- intensity monochrome blue CRT member.

26. The wide-angle display system according to claim 24, wherein said plurality of CRT members are arranged in the shape of an equilateral triangle with said high-intensity monochrome green CRT member being disposed in a top position, and sais high- intensity monochrome red CRT member and said high-intensity monochrome blue CRT member each being disposed in a bottom position.

27. The wide-angle display system according to claim 23, wherein each said CRT member comprises: a CRT housing; a high-intensity monochrome CRT carried by said CRT housing; and a cooling element.

28. The wide-angle display system according to claim 23, wherein the selected dihedral angle is between 0.75° to 1.75°.

29. The wide-angle display system according to claim 23, wherein said lens assembly comprises: at least one lens; at least one static focus adjustment; and at least one dynamic focus adjustment.

30. The wide-angle display system according to claim 28, wherein image distortions are corrected.

31. A method of displaying a wide-angle image on at least one panoramic display screen, the method comprising the steps of: providing an image projector for projecting said wide-angle image ; coupling a plurality of CRT members to said image projector; controlling the plurality of CRT members with at least one image generator; coupling a lens assembly to each said CRT member; and disposing an adapter plate between each said CRT member and each said lens assembly.

32. The method according to claim 31, wherein the step of coupling a plurality of CRT members to said image projector comprises the steps of: coupling a high- intensity monochrome green CRT member to said image projector; coupling a high-intensity monochrome red CRT member to said image projector; and coupling a high-intensity monochrome blue CRT member to said image projector.

33. The method according to claim 32, wherein said high- intensity monochrome green CRT member is coupled to said image projector above said high-intensity monochrome red CRT member and said high- intensity monochrome blue CRT member.

34. The method according to claim 31, wherein the step of coupling a plurality of CRT members to said image projector comprises the steps of: providing a CRT housing; coupling a monochrome CRT to said CRT housing; and coupling an adapter housing to said CRT housing.

35. The method according to claim 31, wherein the step of disposing an adapter plate between each said CRT member and each said lens assembly comprises the steps of: forming a first surface on said adapter plate; and forming a second surface on said adapter plate at a selected angle to said first surface such that a longitudinal axis of said lens assembly forms said selected angle with a longitudinal axis of said CRT member.

36. The method according to claim 35, wherein said selected angle is in a range of 0.75° to 1.75°.

37. An apparatus for retrofitting into an existing wide-angle display system having an existing power supply, existing control circuitry, at least one existing image projector for projecting an image onto at least one existing panoramic display screen, at least one existing CRT member, an existing lens assembly coupled to said at least one existing CRT member, and at least one image generator for controlling said at least one CRT member, the apparatus comprising: at least one replacement CRT assembly including a means for correcting image distortions, said CRT assembly being adapted to replace said at least one existing CRT member and said existing lens assembly.

38. The apparatus according to claim 37, wherein said at least one replacement CRT assembly comprises: a replacement CRT housing; a replacement CRT member carried by said replacement CRT housing, said replacement CRT member being adapted to be controlled by said at least one existing image generator; an adapter housing coupled to said replacement CRT housing; and a replacement lens assembly coupled to said adapter housing; said means for correcting image distortions being an adapter plate disposed between said replacement CRT housing and said replacement lens assembly, said adapter plate having a first surface being configured for coupling to said adapter housing, and a second surface disposed at a selected angle to said first surface, said second surface being configured for coupling to said replacement lens assembly.

39. The apparatus according to claim 38, wherein said selected angle is in a range of 0.75° to 1.75° such that said adapter plate provides correction for image distortion.

40. The apparatus according to claim 37, further comprising: replacement control circuitry configured to replace said existing control circuitry.

41. The apparatus according to claim 40, wherein said replacement control circuitry comprises : at least one dropping resistor and connector interchange unit for adjusting an existing power output from said existing power supply to match a power requirement for said replacement CRT member .

42. The apparatus according to claim 41, wherein said at least one dropping resistor and connector interchange unit reduces said existing power output .