WO2000010156A1

WO2000010156A1 - Head mounted display system with flexible display module support

Info

Publication number: WO2000010156A1
Application number: PCT/US1999/018103
Authority: WO
Inventors: Joel Robinson; Wes Williams; George W. Cone; Dallas Soward
Original assignee: Virtual Vision, Inc.
Priority date: 1998-08-12
Filing date: 1999-08-10
Publication date: 2000-02-24
Also published as: EP1135765A1; JP2002523002A; CA2340063A1

Abstract

A head mounted display system (10) includes an improved image display module (14) and flexible support (90) therefore that allows the user to position the displayed image wherever he wants. The support includes a flexible arm formed of a number of interlocking ball and socket members that allow each member to pivot and rotate with respect to the adjacent member so as to allow the position of the image display module (14) to be simultaneously adjusted relative to three perpendicular axes and to be rotated as well. The flexible support arm is, however, sufficiently rigid to maintain the position of the image display module (14) when set. The display system further includes a mounting for a focusing optic in the display module that allows the optic to be axially moved while preventing rotation thereof wherein this mounting is extremely compact and suitable for an image display module (14) in a head mounted display system (10).

Description

HEAD MOUNTED DISPLAY SYSTEM WITH FLEXIBLE DISPLAY MODULE SUPPORT

BACKGROUND OF THE INVENTION

Binocular and monocular head mounted display systems are known in which a display and/or the associated optics for viewing the display are mounted in fixed positions.

Examples of a monocular system with a fixed position display are shown in United States Patents Furness et al. 5,162,828 and Heacock et al. 5,539,422. In these systems a display and an associated optical system are mounted on a frame relative to either a user's right eye or left eye so that the user can view, with one eye, an enlarged image that appears at a distance from the user that is greater than the optical path from the display to the user's eye. However, most people are either right eye dominant or left eye dominant. A right eye dominant person has trouble viewing an image projected only in front of his left eye. Similarly, a left eye dominant person has trouble viewing an image projected only in front of his right eye. As such, a right eye display system is preferable for a right eye dominant person and a left eye display system is preferable for a left eye dominant person. Because the display is typically mounted in a fixed position on the frame relative to a single image viewing eye in known head mounted display systems, one system cannot typically be used by both right eye and left eye dominant users.

Binocular head mounted display systems with fixed position displays and/or associated optics are also limited in the number of people that such systems can accommodate. For example, some binocular head mounted display systems, as well as monocular systems, require the optics associated with a display to be in a particular position with respect to the user's eye. Because people have different head sizes and different interpupillary distances, designing a system that can accommodate a large number of users is very difficult.

Moreover, it is often desirable to vary the position of the display and/or optics for various applications. For example, for some applications it is desirable to have the displayed image in the user's direct field of view. However, the user might want to reposition the displayed image for other applications. Often, a user will want to move the displayed image out of his field of view temporarily without taking the head mounted display system off his head. Heretofore, known head mounted display systems have not afforded such flexibility.

Further, it is often desirable to allow a user to change the focus of the system. This is accomplished by moving a lens axially with respect to a display or image plane.

However, in known head mounted display systems, the axial movement of the lens is typically accompanied by rotational movement. For example, the lens can be mounted to follow a helical track or the like that moves the lens axially as the lens is rotated. When the lens is spherical, rotation of the lens does not affect the optical characteristics of the system. However, when the lens is aspheric, square, rectangular, etc., rotation of the lens will affect the optical characteristics and can lead to distortion.

BRIEF SUMMARY OF THE INVENTION In accordance with the present invention, the disadvantages of prior head mounted display systems have been overcome. The head mounted display system of the present invention includes a flexible mounting for a display module so that the displayed image can be positioned wherever the user wants. The head mounted display system of the present invention thus accommodates a much larger group of user than heretofore possible.

More particularly, the head mounted display system of the present invention includes a frame that is worn on a user's head. An image display module includes a module housing, at least one display and at least one optic mounted in the housing for magnifying a displayed image. A support arm is mounted on the frame for supporting at one end thereof the image display module. The support arm is flexible over at least a portion of the length of the arm to allow the position of the image display module to be simultaneously adjusted relative to three perpendicular axes and to be rotated or pivoted as well. Although the support arm is extremely flexible, it is sufficiently rigid to maintain the position of the image display module when set. In one embodiment of the present invention, the flexible portion of the support arm is formed of a plurality of interlocking ball and socket members. Each member can pivot or rotate with respect to its adjacent member so that the image display module can be moved vertically, horizontally, towards and away from the user's eye as well as rotated or angled with respect to the user's eye. The fit between a ball and socket is fairly tight so that once the flexible support arm is moved into position it remains in that position.

When used in a monocular head mounted display system, the flexible support arm allows the system to be easily converted from a right eye display to a left eye display. Further, whether used in a monocular or a binocular head mounted display system, the flexible support arm allows the user to position the displayed image wherever the user wants.

In accordance with another feature of the present invention, the display module includes a focusing optic that is mounted to allow axial movement of the optic but that prevents rotation thereof. The mounting of the focusing optic allows an aspheric lens, square lens, etc. to be moved relative to the display or an image plane. Because the mounting is very compact, it is especially well-suited for a head mounted display system.

These and other advantages and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

Fig. 1 is a front perspective view of a head mounted display system of the present invention for right eye viewing of an enlarged displayed image;

Fig. 2 is a front view of the head mounted display system with a frame positioned as in Fig. 1 but with a support arm moved so that an image display module is positioned above the frame;

Fig. 3 is a front perspective view of the head mounted display system of Fig. 2, flipped over to an inverted position to provide a left eye monocular display system;

Fig. 4 is a top perspective view of the head mounted display system of Fig. 2; Fig. 5 is a top view of the head mounted display system of Fig. 3; Fig. 6 is a side view of the display and associated optical system of the image display module depicted in relation to a user's eye; Fig. 7 is a block diagram of an image display controller for generating an image for viewing when the frame is to be worn in one position and for generating an inverted image for viewing when the frame is to be worn in an inverted position;

Fig. 8 is a perspective view of a second embodiment of a head mounted display system of the present invention; and Fig. 9 is a partial perspective view of a cut-away of the display module illustrating the focusing mechanism and eyeshade mounting for the embodiment of the present invention depicted in Fig. 8.

DETAILED DESCRIPTION OF THE INVENTION

A head mounted display system 10 in accordance with the present invention, as shown in Fig. 1, has a frame 12 and an image display module 14 supported on the end 15 of a movable support arm 16. The image display module 14 includes a miniature display or micro-display and an associated optical system to project an enlarged image of the image depicted on the display at a distance from the user that is greater than the optical path from the display to the user's eye. The frame 12 includes a front portion or visor 18 that extends outwardly from the user's forehead when the system 10 is worn. The visor 18 shades the user's eyes and the display module from overhead light for better viewing of the image. A pair of side portions or temples 20 and 22 extend back from the visor 18 to support the frame 12 on the user's head. The sides 20 and 22 are preferably pivotally connected to the visor 18 by respective connectors 24 and 26 to enable the frame to be folded, in a manner similar to a pair of eyeglasses, when the system 10 is not in use.

The support arm 16 is pivotally mounted via a pivot connector 28 on one side 22 of the frame 12 to allow the image display module to be moved above and below the visor 18 so as to convert the head mounted display system 10 from a right eye monocular display system to a left eye monocular display system as discussed in detail below. The support arm 16 is flexible over at least a portion of the length of the arm 16 to allow the position of the image display module to be simultaneously adjusted relative to three perpendicular axes. The flexible support arm also allows the display module to be pivoted or rotated. Because the display module can be positioned wherever the user wants by the flexible support arm, the head mounted display system 10 can accommodate different users more easily than heretofore possible. However, the support arm 16 is sufficiently rigid so as to maintain a position when set.

One suitable configuration of the support arm 16 includes a number of interlocking members 30 wherein each member 30 has a ball 32 at one end and a socket 33 at an opposite end. The members are connected by inserting or snapping the ball 32 of one member into the socket 33 of an adjacent member. The ball and socket connectors, allow each of the members to pivot and/or rotate with respect to its adjacent member 30. The fit between a ball and socket is fairly tight however so that once the arm is moved into position it remains in that position. This flexibility of the support arm allows the arm to be adjusted so that the image display module 14 can be moved vertically or horizontally with respect to the user's eye and towards and away from the user's eye. The construction of the support arm allows movement of the display module relative to these three perpendicular axes simultaneously. This construction of the support arm 16 further allows the image display module 14 to be rotated in any position so that it can be angled with respect to the user's eye. The flexibility of the support arm 16 enables the head mounted display system 10 to accommodate different users very easily. It is noted, that the interlocking members 30 may be encased in a heat shrinkable cover or tube such as formed of plastic so as to prevent the members 30 from inadvertently being disconnected and to aid in maintaining the position of the support arm 16 when set. However, depending upon the interconnecting fit of the interlocking members, such a cover may not be necessary.

The interlocking members 30 of the support arm 16 preferably include an aperture 31 that extends centrally therethrough. A cable 27 from the image display module 14 is routed through the apertures 31 in the members 30 along the length of the arm 16 so that the cable 27 exits an end 35 of the arm. As shown in Figures 4 and 5, a grommet 37 can be used to form a loop 43 in the cable 27 wherein the cable 27 passes through an aperture in the grommet 37 twice. The loop 43 can be fastened about a hook 45 or protrusion on the frame side portion 20 opposite the side 22 on which the arm 16 is mounted. This configuration allows the cable 27 to tighten the frame about the user's head so that the frame can be firmly maintained on different sized heads. It further moves the cable 27 towards the rear of the system 10 so that it is less obtrusive to the user. The cable 27 may be connected to a portable controller or the like for the display module. In order to overcome problems with binocular rivalry in a monocular head mounted display system, a semi-transparent eye shade 36 is provided for partially occluding the user's view of the real world through the non-image viewing eye. The eye shade 36 is preferably semi-transparent such as a dark sunglass lens so that the user can see through the eye shade 36 but the images viewed therethrough are suppressed by being substantially darkened or shaded. The eyeshade may also have a diffuse coating that blurs vision through the eyeshade 36 to suppress images viewed therethrough even further. The size of the eye shade 36 is preferably approximately the size of the display module 14 when viewed from the front so as to provide a balanced appearance. The eye shade 36 is, however, preferably small enough to maintain the user's peripheral vision unobstructed. It is noted, that the size of the eye shade 36 may be reduced to obscure only a portion of the user's central field of view from the non-image viewing eye and still overcome binocular rivalry. Further, if desired, the eye shade 36 may be totally occluding. In order to accommodate users with different interpupillary distances, the eye shield 36 is movably mounted with respect to the image display module 14. More particularly, a small arm or rod 38 has a flange 47 at one end that extends perpendicular to the rod 38. The flange 47 extends through an aperture in a connector 49 to mount the rod 38 on a housing 39 of the display module 14. The rod 38 extends laterally outward from the display module 14 and through an aperture 41 in a connector 40 mounted on the eye shade 36. The rod 38 is preferably movable within the aperture 41 of the connector to allow positioning of the eye shade 36 closer to the image display module 14 or farther therefrom so as to accommodate different interpupillary distances. The flange 47 of the rod is further, preferably moveable within the connector 49 so that the eye shade can be vertically adjusted as well.

The frame 12 of the present invention is generally symmetrical about a horizontal axis 50 that extends through the center of the visor 18 from the right side thereof to the left side thereof. The symmetry allows the frame 12 to appear visually the same when worn in a first position as shown in Fig. 1 as when the frame 12 is flipped over into an inverted position and worn to provide a left eye monocular display as depicted in Fig. 3. Therefore, the bottom of the frame 60 and in particular the visor 18 appears the same as the top 62 of the frame and/or visor 18. Although the frame 12 is generally symmetrical, it need not be completely symmetrical. For example, in a preferred embodiment, the temples or sides 20 and 22 of the frame are slightly vertically offset so that when the temples 20 and 22 are folded, they do not interfere with each other.

In order to convert the head mounted display system 10 from a right eye monocular display as depicted in Fig. 1 into a left eye monocular display, the support arm 16 is moved from a position where the image display module 14 is positioned below the front portion or visor 18 of the frame 12 to a position where the image display module 14 is above the visor 18 with the frame 12 in a non-inverted position as shown in Fig. 2.

Thereafter, the frame 12 is flipped over by rotating the frame 180° about an axis 52 that extends in a direction generally perpendicular to the length of the visor 18 and the axis 50 and in a direction, generally parallel to at least a portion of the sides 20 and 22 of the frame 12. When the frame 12 is thus flipped over into an inverted position, the image display module 14 is positioned below the visor 18 with the image generated by the image display module 14 being viewable by the user's left eye. In the inverted position, the top of the visor 62 is facing downwards whereas the bottom of the visor 60 is facing upward.

It should be appreciated, that the head mounted display system 10 can be converted from a right eye monocular display system to a left eye monocular display system by first flipping over the frame 12 and then moving the support arm 16 so as to position the image display module 14 on the opposite side of the visor 18. Further, although the left eye monocular display is described as having the frame in an inverted position, it can also be considered the first position in which case the frame for the right eye display would be in the inverted position.

A suitable image display module 14 may include a miniature or micro-display 72 that is viewed through an aspheric lens 74. The aspheric lens 74 may be such as described in United States Patent No. 5,543,816 entitled Head Mounted Display System With

Aspheric Optics. The aspheric lens 74 may include a detractive corrector on a surface 76, a surface 78 or on both surfaces so as to correct for chromatic aberrations in the display system. Further, if desired, another corrective optic may be interposed between the display 72 and the aspheric lens 74. Another suitable image display module is depicted in United States Patent Application Serial No. 09/219,065 filed December 22, 1998 and incorporated herein by reference. This system utilizes a reflective micro-display with a minimal number of optics so as to be extremely compact and lightweight. As such, it is particularly well-suited for the image display module of the present invention. It should be appreciated, however, that other types of image display modules may be utilized in accordance with the present invention as well. For example, the display 72 may be mounted in the housing 39 of the module 14 in a position perpendicular to the position of the display 72 shown in Fig. 6 wherein a reflector or partial reflector is used to reflect the image from the display into the user's eye 70 as will be apparent to one of ordinary skill in the art. It is noted that, with the image display module depicted in Fig. 6, when the head mounted display system 10 is converted as described above from a right eye image display to a left eye image display, the portion of the image that appeared in the upper left of the display prior to the conversion will appear in the lower right of the display after the conversion; and the portion of the image in the lower right of the display before the conversion will appear in the upper left of the display after the conversion. Similarly, the portion of the image depicted in the lower left of the display before the conversion will appear in the upper right of the display after the conversion and the portion of the image that appeared in the upper right of the display before the conversion will appear in the lower left of the display after the conversion. The image will thus appear upside down and right-left, reversed after the conversion if the image is not inverted on the display 72.

In order to invert the image depicted on the display 72 so that it appears to be the same when viewed via the right eye monocular display configuration of the system 10 and when viewed by the user's left eye in the left eye monocular configuration as depicted in Fig. 3, the system 10 includes a controller 84 for inverting the image on the display 72 when the frame is to be worn in the inverted position. A switch 80 mounted on the frame 12, module 14 or controller 84 is moveable between right eye and left eye positions 82 and 83 respectively. When the switch 80 is in the right eye position 82, the controller 84, which may include a microprocessor or the like, writes image data to be depicted on the display 72 into a video buffer 86 in a left to right and top to bottom manner or order so as to provide a bit mapped image of the image to be depicted on the display 72. With the switch 80 in the position 82, the controller reads the data out from the image buffer in the same manner in which the data was written into the buffer. When the switch 80 is moved to the left eye position 83, the controller 84 is responsive to the selection of the left eye monocular display position so as to invert the image either upon writing the image data into the buffer 86 or upon reading the image data out of the buffer 86 to the display 72. More particularly, if the image data is to be inverted upon writing the data into the buffer 86, the controller stores the data in a manner opposite to the storage of the data when the switch 80 is in the right eye position 82 so that the data is written into the buffer 86, for example, from right to left and bottom to top. In this embodiment, the data is read out of the video buffer from left to right and top to bottom in the same manner as the data is read out to the display 72 with the switch 80 in position 82. The image depicted on the display 72 is thereby inverted when the switch 80 is in the left eye position 83 from the image depicted on the display 72 when the switch 80 is in the right eye position 82 so that it appears the same when viewed with the system in the right eye or left eye position. Alternatively, the controller 84 may be responsive to the switch 80 in the left eye position 83 by writing the image data into the video buffer 86 in the same manner as the data is written into the buffer when the switch 80 is in the right eye position 82. However, in this embodiment, the data in the image buffer 86 is read out to the display 72 in the opposite manner when the switch 80 is in the left eye position 83 from the manner in which the data is read out when the switch 80 is in the right eye position 82. Specifically, the data would be read out from the video buffer 86 in this embodiment with the switch 80 in the left eye position 83 from right to left and bottom to top.

In a second embodiment of the present invention as shown in Figs. 8 and 9, the flexible support arm 90 is of a similar interconnecting ball and socket construction as the support arm 16. Each interconnecting member 30, however, is tapered between its socket portion 92 and its ball portion 94. Further, the image display module 14 includes a focus adjustment knob or ring 96 mounted on the module housing 98. The focus adjustment knob 96 is manually rotatable by a user to move a focusing lens or optic axially with respect to a display or image plane to provide a focus adjustment.

As shown in detail in Fig. 9, rotation of the focus adjustment knob or ring 96 results in axial movement of a lens 100 with respect to a display 102 or, in other embodiments, an image plane. Because the lens 100 may be aspheric or square, for example, the lens 100 is mounted in a lens support member 104 that cooperates with the module housing 98 to prevent rotation of the lens 100. Similarly, while the ring 96 can rotate, the module 98 prevents axial movement of the ring 96.

More particularly, the focus adjustment knob or ring 96 includes a flange 106 that is disposed in a detent or aperture 108 of the module housing 98. The walls defining the aperture 108 prevent axial movement of the ring 96 by providing a stop for the flange 106. The aperture 108, however, allows the flange to be rotated therein. An inner surface of the ring 96 is threaded for engagement with a helical thread 110 on an outer surface of the lens support member 104. The helical thread 110 does not extend around the entire outer periphery of the lens support 104. Instead, the support member 104 has at least one flat side 112 that abuts a wall 114 of the housing 98. The wall 114 and flat side 112 of the lens support 104 prevent the lens support 104 and thus the lens 100 from rotating as the ring 96 rotates. As the ring 96 rotates, the threads of the ring engage the threads 110 of the lens support to move the lens support 104 and thus the lens 100 axially with respect to the display 102 or an image plane.

Another feature of the embodiment depicted in Fig. 9 is the mounting of the eyeshade 36 on the module housing 98. This mounting allows the eyeshade 36 to be rotated or flipped up so that it does not block the non-image viewing eye of the user.

More particularly, the eyeshade is mounted on a curved rod 120. The curved rod 120 is such that when it is rotated 90°, the eyeshade is in a position generally perpendicular to the in-use position shown. When rotated 90° from the in-use position, the eyeshade is above the user's eye so that it does not block his direct field of view. By rotating the rod a further 90°, i.e. 180° from the in-use position shown, the eyeshade and rod can be removed from the module's housing 98.

As shown in Fig. 9, one end 124 of the rod 120 is mounted in an aperture 125 formed in the module housing 98. The rod end 124 has a protrusion 126 extending outwardly therefrom wherein the protrusion 126 is urged by a spring 127 against a stop 128 so as to maintain the eyeshade 36 in the in-use position. It should be appreciated that, the stop 128 formed in the module housing 98 continues so as to engage the protrusion 126 when the rod is rotated 90° from the in-use position to maintain the eyeshade 36 in the flipped up position. However, when the rod 120 is rotated 180° from the in-use position, the protrusion 126 disengages the stop to allow the rod 120 to slide out of the aperture 125 in the housing 98 so that the eyeshade 36 can be removed.

The head mounted display system 10 of the present invention is extremely lightweight, compact and flexible. As a monocular system it can be used by both right eye dominant and left eye dominant user. It should be appreciated that the flexible support arm of the present invention may be used to support a binocular display module as well. In such a system, an additional support arm may be employed depending on the weight of the display module to be supported. In either a monocular or a binocular system the flexible support arm allows the position of the display module to be easily adjusted to accommodate large numbers of users.

Many modifications and variations of the present invention are possible in light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as described hereinabove.

Claims

What is claimed and desired to be secured by Letters Patent is:CLAIMS

1. A head mounted display system comprising: a frame to be worn on a user's head; an image display module including a module housing, at least one display and at least one optic mounted in the housing for magnifying a displayed image; and at least one support arm mounted on the frame for supporting the image display module, said support arm being flexible over at least a portion of the length of the arm to allow the position of the image display module to be simultaneously adjusted relative to three perpendicular axes and to be rotated, the flexible portion being sufficiently rigid to maintain the position of the image display module when set.

2. A head mounted display system as recited in claim 1 wherein said optic is an aspheric optic mounted in said housing for only axial movement.

3. A head mounted display system as recited in claim 1 wherein said optic is a square lens mounted in said housing for only axial movement.

4. A head mounted display system as recited in claim 1 wherein said image display module includes a ring manually rotatable, said ring having a threaded aperture and a flange, the ring being mounted in the module housing such that the flange is disposed in a detent formed in the module housing to prevent axial movement of the ring but to allow rotation thereof; and a lens support mounted in the module housing for supporting said optic, the lens support having threads thereon for engagement with the threaded aperture of the ring and a non-threaded surface abutting a surface of the module housing to prevent rotation of the lens support as the ring is rotated but that allows axial movement with respect to a displayed image.

5. A head mounted display system as recited in claim 1 including an eyeshade mounted on the image display module and moveable between a first position wherein said eyeshade is blocking at least a portion of the user's non-image viewing eye and a second position that is approximately 90┬░ from the first position.

6. A head mounted display system as recited in claim 1 wherein said eyeshade is mounted on the image display module via a curved member that is moveable with the eyeshade to position the eyeshade so that it does not block the user's view in the second position.

7. A head mounted display system as recited in claim 5 wherein said eyeshade is moveable to a third position from which it may be removed from the image display module.

8. A head mounted display system as recited in claim 7 wherein said eyeshade is mounted on a first end of a rod having a second end mounted in an aperture in the module housing for rotation therein between the first, second and third positions, the second end of the rod having a protrusion urged by a spring against a stop when in the first or second positions to maintain the eyeshade in position, said protrusion disengaging the stop when moved to the third position to allow the eyeshade to be removed.

9. A head mounted display system comprising: a frame to be worn on a user's head; an image display module including a module housing, at least one display and at least one optic mounted in the housing for magnifying a displayed image; and at least one flexible support arm mounted on the frame for supporting the image display module, said flexible support arm being formed of a plurality of interlocking ball and socket members that allow each member to pivot or rotate with respect to an adjacent member, the flexible support arm being sufficiently rigid to maintain the position of the display module when set.

10. A head mounted display system as recited in claim 9 wherein said flexible support arm includes a heat shrinkable cover.

11. A head mounted display system as recited in claim 9 wherein said interlocking ball and socket members include an aperture therein through which a cable from said image display module extends.

12. A head mounted display system as recited in claim 11 wherein said frame includes a protrusion on a side of the frame opposite to a side of the frame on which the arm is mounted so as to be able to engage a loop formed in the cable.

13. A head mounted display system as recited in claim 9 wherein said optic is an aspheric optic mounted in said housing for only axial movement.

14. A head mounted display system as recited in claim 9 wherein said optic is a square lens mounted in said housing for only axial movement.

15. A head mounted display system as recited in claim 9 wherein said image display module includes a mounting for said optic that allows axial movement of the optic but prevents rotation thereof.

16. A head mounted display system as recited in claim 9 including an eyeshade mounted on the display module and moveable between a first position wherein said eyeshade is blocking at least a portion of the user's non-display viewing eye and a second position that is approximately 90┬░ from the first position.

17. A head mounted display system as recited in claim 16 wherein said eyeshade is moveable to a third position from which it may be removed from the display module.

18. A head mounted display system comprising: a frame to be worn on a user's head; and an image display module mounted on the frame and including a module housing, at least one display and at least one optic for magnifying a displayed image, a manually rotatable ring mounted on the housing to allow rotation thereof but to prevent axial movement of the ring; and a support for said optic, the optic support being mounted in the housing to allow axial movement thereof but to prevent rotational movement of the support and optic, the optic support being engagable by the ring such that as the ring is rotated, the optic support is moved axially.

19. A head mounted display system as recited in claim 18 wherein said ring has a threaded aperture and a flange, the ring being mounted in the module housing such that the flange is disposed in a detent formed in the module housing to prevent axial movement of the ring; and said optic support has threads thereon for engagement with the threaded aperture of the ring and a non-threaded surface abutting a stop on the module housing to prevent rotation of the optic support but to allow axial movement of the optic as the ring is rotated.

20. A head mounted display system as recited in claim 18 including an eyeshade mounted on the display module and moveable between a first position wherein said eyeshade is blocking at least a portion of the user's non-display viewing eye and a second position that is approximately 90┬░ from the first position.

21 A head mounted display system as recited in claim 20 wherein said eyeshade is moveable to a third position from which it may be removed from the display module.

22. A head mounted display system as recited in claim 21 wherein said eyeshade is mounted on a first end of a rod having a second end mounted in an aperture in the module housing for rotation therein between the first, second and third positions, the second end of the rod having a protrusion urged by a spring against a stop when in the first or second positions to maintain the eyeshade in position, said protrusion disengaging the stop when moved to the third position to allow the eyeshade to be removed.

23. A head mounted display system as recited in claim 20 wherein said eyeshade is mounted on the image display module via a curved member that is moveable with the eyeshade to position the eyeshade so that it does not block the user's view in the second position.

24. A head mounted display system comprising: a frame to be worn on a user's head; and an image display module mounted on the frame and including a module housing, at least one display and at least one optic mounted in a support in the housing, a portion of the outer surface of the optic support being threaded and a portion of an outer surface of the optic support being flat and abutting a stop in said housing that allows axial movement of the optic support but prevents rotation thereof and a manually rotatable knob mounted on the housing to prevent axial movement thereof and having threads on an inner surface for engagement with the threaded portion of the optic support to move the optic support axially as the knob is rotated.

25. A head mounted display system comprising: a frame to be worn on a user's head; at least one support arm mounted on the frame; an image display module mounted on the support arm, the image display module including a display and at least one optic for magnifying a displayed image; an eyeshade that is at least partially transparent mounted on said image display module by a second support arm having an end that extends in an aperture in the module housing, said second support arm being movable between a first position in which said eyeshade at least partially occludes a portion of the user's non-image viewing eye, a second position in which said eyeshade is approximately 90┬░ from the first position and is maintained mounted on said image display module but does not block the user's direct view and a third position in which the eyeshade and second support arm can be removed from the system by sliding the second support arm out from the aperture in the module housing.

26. A head mounted display system as recited in claim 25 wherein said eyeshade has a diffuse coating thereon.

27. A monocular head mounted display system convertible from a right eye display to a left eye display comprising: a frame to be worn on a user's head in a first position and, when flipped over, to be worn in an inverted position; an image display module for generating an image; a support arm mounted on the frame for supporting the image display module, the support arm being moveable to position the image display module above or below the frame in the first position so that when the image display module is positioned below the frame in the first position the generated image is viewable by one of the user's eyes and when the image display module is positioned above the frame in the first position and the frame is flipped over to the inverted position, the display module is below the frame in the inverted position with the generated image being viewable by the other of the user's eyes.

28. A monocular head mounted display system convertible from a right eye display to a left eye display as recited in claim 27 wherein said frame is generally symmetrical about a horizontal axis so that when the frame is worn in the first position it appears the same as when the frame is flipped over to the inverted position.

29. A monocular head mounted display system convertible from a right eye display to a left eye display as recited in claim 27 wherein said support arm is adjustable to allow the image display module to be moved vertically with respect to a user's eye, horizontally with respect to the user's eye and towards and away from the user's eye.

30. A monocular head mounted display system convertible from a right eye display to a left eye display as recited in claim 27 wherein said support arm is flexible over at least a portion of the length of the arm to allow the position of the image display module to be adjusted relative to three perpendicular axes to accommodate different users but the support arm is sufficiently rigid so as to maintain a position when set.

31. A monocular head mounted display system convertible from a right eye display to a left eye display as recited in claim 30 wherein said support arm includes a plurality of interlocking members having ball and socket connectors with a heat shrinkable cover thereover.

32. A monocular head mounted display system convertible from a right eye display to a left eye display as recited in claim 27 wherein said image display module includes a display, the display being coupled to an image buffer that stores data representing an image or an inverted image for display depending upon whether the frame is to be worn in the first position or in the inverted position.

33. A monocular head mounted display system convertible from a right eye display to a left eye display as recited in claim 27 wherein said image display module includes a display, the display being coupled to an image buffer that stores data representing an image, the image data being read out from said image buffer in one order for a frame in the first position and the image data being read out from said image buffer in an opposite order for a frame in the inverted position.

34. A monocular head mounted display system convertible from a right eye display to a left eye display as recited in claim 27 including a semi-transparent eye shade mounted on said image display module so as to be positioned in at least a portion of the user's central field of view of the non-image viewing eye.

35. A monocular head mounted display system convertible from a right eye display to a left eye display as recited in claim 34 wherein said eye shade is adjustably mounted on said display module so as to accommodate different interpupillary distances.