(12> Ulllted States Patent
`Heac0ck et al.
`
`US006232934B1
`(16) Patent N6.=
`US 6,232,934 B1
`(45) Date 0f Patent:
`May 15, 2001
`
`(54) BINOCULAR HEAD MOUNTED DISPLAY
`
`4,559,555 * 12/1985 Schoolman ........................... .. 358/88
`
`SYSTEM
`
`
`
`(75) Inventors: Gregory Lee Heacock, Camas; ~ _
`
`
`
`4,869,575 * 9/1989 Kubik . . . . . .
`
`4,982,278 * 1/1991 Dahl
`
`. . . . .. 345/8
`
`358/92
`
`-
`
`,
`
`,
`
`
`
`* *
`
`
`
`itaveley awamura ..
`
`
`
`~~~~ ~~ ..
`
`a,"211311112;aillegzt?ghb/?iiglfawlfzgls)
`'
`>
`’
`
`.. 345/8
`5,189,512 * 2/1993 Cameron
`5,281,957 * 1/1994 Schoolman ............................. .. 345/8
`
`(73) Assignee: Virtual Vision, Redmond, WA (US)
`
`OTHER PUBLICATIONS
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U~S-C- 154(k)) by 0 days-
`
`gllgoflélsbq'z/zag
`lgest p
`* cited by examiner
`
`'
`
`Eyeglasses Heads—UP Display”
`
`(21) Appl' NO': 08/419’064
`(22) Filed:
`Apr. 10, 1995
`
`Related US. Application Data
`
`(63) Continuation of application N°~ 08/133518: ?led on Oct- 7:
`1993’ now abandoned
`(51) Int. Cl.7 ..................................................... .. G09G 5/00
`(52) US. Cl. .................................................... .. 345/8; 345/7
`(58) Field Of Search ........................ .. 345/7, 8, 9; 358/88,
`358/92. 359/13 630 631 632 633 466
`’
`’
`’
`’
`’
`’ 472’
`
`(56)
`
`References Cited
`
`Us PATENT DOCUMENTS
`1,440,457 * 1/1923 Girsdansky ........................ .. 359/472
`2,463,311 * 3 /1949
`__ 359/466
`2,955,156 * 10/1960
`358/88
`3,670,097
`6/1972
`.. 359/472
`358/88
`4,190,856
`2/1980
`
`*
`
`Primar Examiner—MattheW Luu
`(74) Atliorney, Agent, or Firm—McAndreWs, Held &
`Malloy, Ltd.
`
`ABSTRACT
`(57)
`A binocular head mounted display unit utilizing a single
`display and binocular optical system is shoWn for projecting
`an enlarged image of displayed information in the direct line
`of Sight and central ?eld of view of each of the user’s eyes,
`While maintaining the user’s peripheral vision free from
`obstruction to allow the user to Selectively feeus en the
`virtual image or not. The binocular optical system directs the
`user’s eyes inWard at an angle that is natural for a person
`vieWing an object at a distance that is less than in?nity.
`Further, the binocular optical system automatically compen
`sates for variations in the interpupillary distances of various
`users, Wherein those variations may be as great as one inch.
`This head mounted display unit is Suitable for a Variety of
`applications, including virtual reality applications, as Well as
`a display for a compact portable computer.
`
`45 Claims, 15 Drawing Sheets
`
`IPR2018-01045
`Sony EX1020 Page 1
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 1 0f 15
`
`US 6,232,934 B1
`
`IPR2018-01045
`Sony EX1020 Page 2
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 2 0f 15
`
`US 6,232,934 B1
`
`FIG. 24
`
`IPR2018-01045
`Sony EX1020 Page 3
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 3 0f 15
`
`US 6,232,934 B1
`
`24
`
`IPR2018-01045
`Sony EX1020 Page 4
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 4 0f 15
`
`US 6,232,934 B1
`
`FIG. 5
`
`52
`
`34
`
`,
`
`42
`
`_
`‘i
`
`l
`
`
`
`/ % 1% I
`|
`l
`L-w- j +-w
`
`k
`
`30
`
`40
`50
`28
`
`_
`
`4
`
`FIG. 6
`m22AL¢ L
`l \56
`eh
`/ l>\l
`
`FIG. 1
`
`Q Q. A
`
`\
`
`r-I-——-—IPD———" é\
`
`'
`
`FIG. 8
`
`E
`
`L-Bj
`
`IPR2018-01045
`Sony EX1020 Page 5
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 5 0f 15
`
`US 6,232,934 B1
`
`FIG. 9
`
`l6
`
`l4
`
`34
`
`32
`
`24
`_—_N
`I
`,
`1
`\y 7,
`I- —
`
`I‘
`ll
`/Jl
`/ {l
`
`,
`58'
`
`42
`
`40
`
`FIG. IO
`
`2a
`
`42
`
`34
`
`36
`
`4o
`28
`32
`
`
`
`% 1/1 W: ea/Ltzz 6|S
`
`i<50
`
`IPR2018-01045
`Sony EX1020 Page 6
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 6 0f 15
`
`US 6,232,934 B1
`
`FIG. I I
`42
`
`64
`
`36
`
`34
`
`28'
`32
`
`FIG. l2 <
`
`IPR2018-01045
`Sony EX1020 Page 7
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 7 0f 15
`
`US 6,232,934 B1
`
`IPR2018-01045
`Sony EX1020 Page 8
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 8 0f 15
`
`US 6,232,934 B1
`
`1/ ‘28
`
`I00
`
`IPR2018-01045
`Sony EX1020 Page 9
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 9 0f 15
`
`US 6,232,934 B1
`
`28
`
`IPR2018-01045
`Sony EX1020 Page 10
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 10 0f 15
`
`US 6,232,934 B1
`
`IPR2018-01045
`Sony EX1020 Page 11
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 11 0f 15
`
`US 6,232,934 B1
`
`IPR2018-01045
`Sony EX1020 Page 12
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 12 0f 15
`
`US 6,232,934 B1
`
`FIG. I9
`
`242
`
`IPR2018-01045
`Sony EX1020 Page 13
`
`

`

`U.S. Patent
`
`May15, 2001
`
`Sheet 13 of 15
`
`US 6,232,934 B1
`
`Be”oywwd
`
`Zaee”FLteXeBD5
`A(TTggilit’s|AttTA
`
`
`
`eth
`
`3\'
`
`
`
`IPR2018-01045
`Sony EX1020 Page 14
`
`IPR2018-01045
`Sony EX1020 Page 14
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 14 0f 15
`
`US 6,232,934 B1
`
`IPR2018-01045
`Sony EX1020 Page 15
`
`

`

`U.S. Patent
`
`May 15,2001
`
`Sheet 15 0f 15
`
`US 6,232,934 B1
`
`FIG. 26
`
`IPR2018-01045
`Sony EX1020 Page 16
`
`

`

`US 6,232,934 B1
`
`1
`BINOCULAR HEAD MOUNTED DISPLAY
`SYSTEM
`
`This is a continuation of application Ser. No. 08/133,518
`?led Oct. 7, 1993 noW abandoned.
`
`TECHNICAL FIELD
`The present invention is directed to a head mounted
`display system and more particularly to a single display,
`binocular system that projects an image in the direct line of
`sight of the user’s eyes While maintaining the user’s periph
`eral vision relatively free from obstruction to alloW the user
`to selectively focus on the virtual image or not.
`
`BACKGROUND OF THE INVENTION
`
`Binocular head mounted display systems alloW a user to
`vieW an image or images of displayed information With both
`eyes. Typical binocular head mounted display systems
`include tWo displays, one for each of the user’s eyes, as Well
`as tWo sets of identical optics so as to be very costly and
`heavy. Binocular head mounted display systems that include
`only a single display are also knoWn. Both types of systems
`typically direct the user’s eyes such that the axes of the eyes
`are parallel for vieWing a projected image focused at in?nity.
`For virtual reality applications in Which the user is to be
`totally immersed in the video image, these binocular sys
`tems are further formed so that the user’s ?eld of vieW is
`completely blocked, the user being unable to see anything
`but the displayed image.
`These knoWn systems have a number of problems. For
`example, it has been found that With head mounted display
`systems in Which the user cannot focus on anything but the
`projected image, eye fatigue often occurs. Such systems can
`cause feelings of claustrophobia because the user’s vieW is
`completely enclosed and feelings of anxiety because the user
`can hear things going on in his surroundings but is not able
`to see What is happening. With these systems the user can
`also experience “sea sickness” When the motion of the image
`that he is vieWing does not coincide With the motion that the
`user’s body is experiencing.
`Binocular systems in Which the user’s eyes are directed
`such that the axes of the eyes are parallel have been found
`to contribute to eye fatigue When the image is focused at less
`than in?nity. Eye fatigue and feelings of discomfort result
`because it is unnatural for a person’s eyes to be such that the
`axes of the eyes are parallel When vieWing an image that is
`only tWo or three feet aWay.
`KnoWn binocular systems are typically designed for users
`having a particular “average” or “normal” interpupillary
`distance (hereinafter referred to as IPD). Because the IPD of
`users can vary considerably, these systems are usable only
`by a very limited portion of the population and are not
`suitable for general consumer applications. If a user has an
`IPD that varies considerably from the average IPD for Which
`the system is designed his eye Will be off of the axis of the
`optical system. User’s Who are off-axis typically see right
`eye and left eye images that do not line up. They may also
`see distortions in the image Wherein one side of the image
`Will look bigger than the other side, and/or a part of the
`image Will be in focus While other parts of the image Will be
`out of focus. Further, a portion of the image depicted on the
`display may be cut off When vieWed off axis through the
`optics of the system.
`SUMMARY OF THE INVENTION
`In accordance With the present invention, the disadvan
`tages of prior binocular head mounted display systems have
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`2
`been overcome. The head mounted display system of the
`present invention is a single display binocular system that is
`usable by a large portion of the population Without modi?
`cation. The head mounted display system of the present
`invention is suitable for applications requiring the user to
`comfortably focus at less than in?nity, as Well as applica
`tions requiring the user to focus at in?nity, and is further
`suitable for applications requiring the user to vieW his
`surroundings While vieWing the projected image, as Well as
`for virtual reality applications.
`More particularly, the head mounted display system of the
`present invention includes a support to mount the display
`system on a user’s head; a single video image source, such
`as a display, that is mounted on the support; and a compact
`binocular optical system of minimal Weight for projecting an
`enlarged virtual image of the video from the image source at
`a distance from the user that is greater than the actual path
`length of the optical system. Because the optical system is
`compact and lightWeight, the support may be similar to the
`frame of a pair of glasses or other conventional eyeWear and
`does not require the support to take the form of a helmet or
`other substantial arrangement in order to act as a counter
`Weight for the optics as in knoWn systems.
`One feature of the binocular optical system of the present
`invention is that it projects a virtual image in the central ?eld
`of vieW of each of the user’s eyes, Wherein the optical
`system and support are such as to maintain at least a portion
`of the peripheral vieW of each of the user’s eyes free from
`obstruction. Because at least a portion of the peripheral vieW
`of each of the user’s eyes is free from obstruction, the user
`can selectively focus on the projected image or not to
`minimiZe or substantially eliminate eye fatigue. Further,
`because the user is visually cogniZant of his surroundings
`While he is vieWing the virtual image, feelings of anxiety and
`claustrophobia are eliminated. It is also noted, that because
`the user can selectively vieW his surroundings, the system of
`the present invention does not promote feelings of “sea
`sickness” as frequently encountered With other systems.
`Although the user can simultaneously vieW his surround
`ings as Well as the virtual image With the head mounted
`display system of the present invention, it has been found
`that the present system creates a feeling of total immersion
`in the video image. Therefore the system is suitable for
`virtual reality applications Without having the problems
`associated With binocular head mounted display systems
`typically used for such applications. This feeling of total
`immersion in the video image With the system of the present
`invention is quite surprising since heretofore it Was thought
`that for total immersion, the user should not see anything but
`the projected video image. It has further been found that
`because the user has at least some vision of the real World,
`as Well as the virtual image, the three-dimensional cues in
`the real World cause the user to perceive that the virtual
`image has depth, ie is three dimensional Without requiring
`a stereo image source.
`Another feature of the binocular optical system of the
`present invention is that it includes a right eye optical
`centerline path and a left eye optical centerline path With at
`least one optical element in each of these paths, Wherein the
`right eye and left eye optical centerline paths are angled in
`toWards the virtual image perceived by the user. Because the
`optical, centerline paths of the system are angle in toWards
`the virtual image, the user’s eyes are directed inWard at an
`angle that is natural for a person vieWing an object at a
`distance that is less than in?nity as opposed to being directed
`so that the axes of the eyes are parallel. With the user’s eyes
`directed naturally inWard to the location of the virtual image,
`
`IPR2018-01045
`Sony EX1020 Page 17
`
`

`

`US 6,232,934 B1
`
`3
`the head mounted display system of the present invention is
`more comfortable and less eye straining than prior systems.
`A further feature of the binocular optical system of the
`present invention is that it automatically compensates for
`variations in the interpupillary distance of different users,
`Wherein those variations may be as great as one inch.
`Therefore, the head mounted display system of the present
`invention is suitable for use by a vast majority of the
`population Without requiring manual adjustment to any of
`the optical elements. In one embodiment, variations in
`interpupillary distance are automatically compensated for
`utilizing in each of the right eye and left eye paths a prism
`that bends the light from any location along the Width
`thereof, representing various positions of users’ eyes With
`different IPDs, toWards a central area on a concave re?ector.
`This concave re?ector focuses the light path from the user’s
`right and left eyes to the same point on the display, Which is
`preferably the center of the display. In another embodiment,
`a focusing lens is disposed in each of the right eye and left
`eye optical paths, such that light at any location along the
`Width, i.e. diameter, of the lens representing various posi
`tions of users’ eyes, is focused on the same point, mirrors
`being disposed in each of the right eye and left eye optical
`paths to direct the path of the light from the user’s eyes
`through the respective lenses to the same point on the
`display.
`In accordance With a further feature of the present
`invention, the binocular optical system may include a semi
`transparent re?ector into Which the user looks to vieW the
`virtual image in a portion of his ?eld of vieW. The display
`may further include a brightness control alloWing the bright
`ness of the display to be varied to cause the virtual image to
`block that portion of the user’s ?eld of vieW in Which the
`image is projected; to cause the virtual image to be super
`imposed on the real World in that portion of the user’s ?eld
`of vieW in Which the image is projected so that both the
`image and the real World in that portion can be simulta
`neously seen by the user; or to cause the virtual image to be
`extinguished from that portion of the user’s ?eld of vieW so
`that the user sees the real World, but does not see the virtual
`image at all. This feature can also be accomplished by
`providing a display Which can be controlled so that light
`does not pass from the display in a de?ned area or WindoW
`thereof. When this light blocking feature of the display is
`actuated, a WindoW into the real World is provided through
`the displayed image and When not actuated, the image is
`seen in its entirety.
`The head mounted display system of the present invention
`is suitable for any application requiring the vieWing of
`displayed information. Because of a number of the features
`noted above, the system of the present invention is emi
`nently suitable for a computer display. Therefore, in accor
`dance With the present invention, the head mounted display
`system forms the display of a computer, the electronics of
`Which are housed in a keyboard housing. The keyboard is
`designed to be compact, and in one embodiment is foldable.
`The keyboard may also include a mounting surface for the
`head mounted display unit so that the computer can be easily
`carried. Because the head mounted display is compact and
`lightWeight, the overall Weight and siZe of the computer in
`accordance With the present invention is greatly reduced
`over prior portable computer systems. The image vieWed by
`the user With the computer display of the present invention
`can be as large or larger than the image depicted on
`conventional non-portable computer displays, unlike the
`displays of typical portable computers. Further, because the
`head mounted display is a personal display unit, only the
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`4
`user can see What is being displayed on his computer so as
`to alloW the user to Work on con?dential information While
`in a public setting, such as on an airplane.
`These and other objects, 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 the draWing.
`
`BRIEF DESCRIPTION OF THE DRAWING
`
`FIG. 1 is a perspective vieW of a head mounted display
`system and keyboard in accordance With the present inven
`tion forming a portable computer;
`FIG. 2 is an exploded, perspective vieW of a head
`mounted display system in accordance With one embodi
`ment of the present invention;
`FIG. 3 is a back perspective vieW of the head mounted
`display system depicted in FIG. 2;
`FIG. 4 is a side vieW of the head mounted display system
`depicted in FIG. 2;
`FIG. 5 is a top vieW of the optics and display of the system
`shoWn in FIG. 2;
`FIG. 6 is a schematic illustration of the convergence angle
`of the user’s eyes When the image is focused at less than
`in?nity With the system depicted in FIG. 5;
`FIG. 7 is a top vieW of a schematic illustrating the user’s
`side peripheral vision that is maintained unobstructed by the
`optical system of the present invention;
`FIG. 8 is a front vieW of a schematic illustrating the user’s
`side and loWer peripheral vision that is maintained unob
`structed by the optical system of the present invention;
`FIG. 9 is a bottom vieW of the head mounted display
`system depicted in FIG. 2 modi?ed With the addition of a
`movable eye block so as to make the system monocular;
`FIG. 10 is a top vieW of the optics of FIG. 5 modi?ed in
`accordance With another embodiment of the head mounted
`display system of the present invention;
`FIG. 11 is a top vieW of the optics and display for a head
`mounted display system in accordance With still another
`embodiment of the present invention;
`FIG. 12 is an exploded, perspective vieW of a folded
`embodiment of the head mounted display system shoWn in
`FIG. 2;
`FIG. 13 is a top vieW of the optics for a further embodi
`ment of the head mounted display system of the present
`invention depicting alternative locations for the mounting of
`the display used therein;
`FIG. 14 is a side vieW of a folded embodiment of the head
`mounted display system depicted in FIG. 13;
`FIG. 15 is a schematic diagram of the optics in accordance
`With a further embodiment of the head mounted display
`system of the present invention Wherein dotted lines repre
`sent mirror folds of the system;
`FIG. 16 is a perspective vieW of a keyboard as shoWn in
`FIG. 1 partially folded;
`FIG. 17 is a perspective vieW of the keyboard of FIG. 16
`folded;
`FIG. 18 is a top perspective vieW of the bottom housing
`and hinge assembly of the keyboard of FIG. 16;
`FIG. 19 is an exploded, perspective vieW of the hinge
`assembly of the keyboard depicted in FIG. 16;
`FIG. 20 is a perspective vieW illustrating another embodi
`ment of the foldable keyboard of the present invention;
`FIG. 21 is a back vieW of the keyboard of FIG. 20
`illustrating an alternative hinge arrangement;
`
`IPR2018-01045
`Sony EX1020 Page 18
`
`

`

`US 6,232,934 B1
`
`5
`FIG. 22 is a partial side vieW of the hinge arrangement of
`FIG. 21 Wherein the hinge is in a non-folded position;
`FIG. 23 is a partial side vieW of the hinge illustrated in
`FIG. 22 in the folded position;
`FIG. 24 is a perspective vieW of an alternative embodi
`ment of the foldable keyboard of the present invention
`including a mounting surface for the head mounted display
`unit;
`FIG. 25 is a bottom vieW of the portable computer system
`depicted in FIG. 24; and
`FIG. 26 is a perspective vieW of a head mounted display
`system mounted on the keyboard of FIG. 24 in its folded
`position.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`The head mounted display unit 10 of the present invention
`as shoWn in FIG. 1 includes a frame 12 that is Worn on a
`user’s head and that supports a display 28 and associated
`binocular optics, as discussed in detail beloW for the various
`embodiments thereof. The frame 12 may also support the
`drive electronics for the display and a pair of earphones 14,
`16 that provide audio for the unit 10. As is Well knoWn, the
`drive electronics for the display are responsive to standard
`video input signals to drive the display to depict video
`information. To reduce the Weight of the head mounted
`display unit 10 and to alloW the head mounted display unit
`10 to provide a universal video display that may receive
`video inputs from any one of a number of sources, the video
`input signal generator is preferably a separate, remote unit.
`The video input signal generator may take the form of a
`television tuner, video camera, video player, video game,
`computer, or other device that generates a video input signal.
`For example, as shoWn in FIG. 1, the head mounted display
`unit 10 forms the display of a computer, the electronics for
`Which are housed Within a keyboard housing 18. Although
`the head mounted display system may be coupled to the
`video input signal generator and/or audio generator by a
`cable 20, as shoWn, the unit 10 need not be physically
`connected to the video/audio input signal generator. For
`example, the video and audio input signals may be RF
`modulated and transmitted from the remote unit to a head
`mounted display unit 10 that includes an RF receiver as
`described in detail in US. patent application Ser. No.
`07/986,422, ?led Dec. 4, 1992, assigned to the Assignee of
`the present invention and incorporated herein by reference.
`Abinocular head mounted display system in accordance
`With one embodiment of the present invention is depicted in
`FIGS. 2—6. In this embodiment, the frame 12 of the head
`mounted display unit 10 includes a top cover 22 and a
`bottom cover 24 forming a housing for a circuit board 26 on
`Which may be mounted the drive electronics for the display
`28 and the speakers 14 and 16 and/or an RF receiver. The
`bottom cover 24 forms a support for mounting the display 28
`and the optics for the unit 10 Which include a semi-re?ective
`visor 36 and a prism 30.
`More particularly, the display 28 may be a liquid crystal
`display or the like for depicting video information on a
`surface 40 that faces the inner surface 42 of the re?ective
`visor 36. The display 28 preferably has VGA resolution so
`as to be suitable for displaying standard computer generated
`alphanumeric information and video graphic images. It is
`noted that liquid crystal displays are typically con?gured
`With a back light such that the light shines through the
`display from the back thereof. When the liquid crystal
`display is vieWed from the front, an image appears in the
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`6
`proper orientation When driven by conventional signals that
`are used to drive a CRT, for example. This type of conven
`tional liquid crystal display is hereinafter referred to as a
`right-handed display. In the embodiment of the optical
`system depicted in FIGS. 2—6, the information depicted on
`the display 28 is re?ected by the visor 36 so that it may be
`vieWed by a user. Because the optical system includes an
`odd number of re?ectors, the image Which Would be seen by
`the user, if a conventionally mounted right-handed liquid
`crystal display Were employed, Would be reversed from right
`to left. Although this reversal may not be noticeable for
`non-text video information, alphanumeric text displayed
`backWards Would not be readable by a user. This problem
`can be overcome by inserting another re?ector in the optical
`path, although the additional re?ector increases the Weight
`of the unit. Another option is to control the image source to
`output a reversed image. This option Would, hoWever,
`require non-standard and complicated electronics. In the
`preferred embodiment, the reversal of the image is corrected
`by removing the back light from the back surface of a
`conventional “right-handed” liquid crystal display; mount
`ing the liquid crystal display in a reverse right-to-left ori
`entation so that it forms a left-handed display With the
`conventional back of the display forming the vieWable
`image surface 40 and mounting the back light on the
`conventional front surface of the display. When the liquid
`crystal display is oriented in this manner, it may be driven
`in a conventional manner such that the image, When vieWed
`directly, Will appear in a reverse orientation. HoWever, When
`a user vieWs the image as re?ected from the display by the
`visor 36, alphanumeric text Will appear in the proper right
`to-left orientation.
`The binocular optical system of the embodiment of FIGS.
`2—6 includes prism elements 32 and 34 disposed respec
`tively in a right-eye path 50 and a left-eye path 52 so as to
`bend light from any position along the Width, W, of the prism
`32, 34 toWards a central area C of the visor 36. The visor 36
`is a concave re?ector that directs both the right-eye optical
`centerline path and the left-eye optical centerline path to the
`same point on the face of the display 28. When the image of
`the information depicted on the display 28 is to appear at
`optical in?nity, the display should be located With respect to
`the re?ective visor 36 such that the focal point of the visor
`36 is at the center of the display.
`When the image of the information depicted on the
`display is to appear at less than in?nity, such as for vieWing
`displayed alphanumeric information, the display 28 is
`located at a distance from the visor 36 that is less than the
`focal length of the visor 36, Wherein the optical centerline or
`chief ray 54 of the visor intersects the center of the display.
`In this later instance, the prisms 32 and 34 are mounted on
`the bottom cover 24 so that the optical centerline of each
`prism 32, 34 is angled in toWards the location of the virtual
`image to thereby cause the user’s eyes to angle in slightly to
`vieW the virtual image. The angle of each of the prisms 32
`and 34 and the angle of the user’s eye When looking in
`toWards the virtual image is referred to as the convergence
`angle 6. The convergence angle 6 is shoWn in FIG. 6 With
`respect to the axis 56 of the eye When looking straight ahead.
`The convergence angle is selected to be approximately equal
`to the natural inWard angle of the eyes When vieWing an
`object at the same distance from the user as the distance that
`the virtual image appears. The convergence angle is very
`small being on the order of 2°—4° for a virtual image that
`appears approximately tWo feet or 0.75 m from the user. As
`the virtual image is moved closer to optical in?nity, the
`convergence angle is reduced to Zero. It has been found that
`
`IPR2018-01045
`Sony EX1020 Page 19
`
`

`

`US 6,232,934 B1
`
`7
`by angling the right-eye and left-eye optical centerline paths
`slightly in towards the location of the virtual image, eye
`fatigue is reduced. This is because the user is use to angling
`his eyes in toWards a real object that is located at a distance
`that is less than optical in?nity.
`In accordance With an important feature of the present
`invention, the optical system is such as to project a virtual
`image in the direct line of sight and central ?eld of vieW of
`each of the user’s eyes so that the displayed information can
`be the main focus of the user’s attention, hoWever the optical
`system and support are also such as to maintain at least a
`portion of the peripheral vieW of each of the user’s eyes free
`from obstruction. As shoWn in FIGS. 7 and 8, the exit
`surface of the optical elernent(s) closest to the user’s eyes,
`Which in the case of FIG. 2 is the prism 30, is represented
`by the line AB Where A and B respectively represent the
`locations of the outer side edges of the closest optical
`elernent(s). The exit surface of the closest optical elernent(s)
`is preferably approximately 20 mm from the user’s eyes.
`The distance W from A to B is preferably on the order 100
`mm so that a user having an IPD of approximately 2.5 inches
`or 64 mm need only move an eye to the side through an
`angle 0t to focus on his surroundings in his side peripheral
`vision. The angle 0t Will vary for users having different IPDs
`but is generally in the range of 5°—15°. In order to maintain
`a substantial portion of the user’s loWer peripheral vision
`unobstructed, the loWer edge E of the closest optical element
`preferably does not extend signi?cantly beloW the bottom of
`the user’s eye. For example, the distance d from the center
`of the closest optical element to the loWer edge E thereof is
`on the order of 9 mm—15 mm.
`With the system depicted in FIGS. 2—6, the user has side
`peripheral vision and a considerable amount of loWer
`peripheral vision. The loWer peripheral vision is important
`so as to alloW the user to be able to vieW the keyboard 18 or
`another device such as a medical or industrial instrument
`Without obstruction. Because at least a portion of the periph
`eral vieW of each of the user’s eyes is free from obstruction,
`the user can selectively focus on the projected virtual image
`or not to minimize or substantially eliminate eye fatigue.
`Further, because the user is visually cogniZant of his sur
`roundings While he is vieWing the virtual image, feelings of
`anxiety and claustrophobia are eliminated. It is also noted,
`that because the user can selectively vieW his surroundings,
`the system of the present invention does not promote feel
`ings of “sea sickness” as frequently encountered With other
`systems.
`Although the user can simultaneously vieW his
`surroundings, as Well as the virtual image of the head
`mounted display system of the present invention, it has been
`found that the present system creates a feeling of total
`immersion in the video image. It has further been found that
`because the user has at least some vision of the real World,
`as Well as the virtual image, the three-dimensional cues in
`the real World cause the user to perceive that the virtual
`image has depth, i.e., is three-dimensional, Without requiring
`a stereo image source.
`The visor 36 is preferably a semi-transparent re?ector,
`being on the order of 80% re?ective so that the user can see
`the real World through the visor 36. In a preferred embodi
`ment of the invention, the display 28 includes a brightness
`control, such as a brightness control knob 65 mounted on the
`frame 12 of the head mounted display unit 10, or mounted
`on the keyboard housing 18. The brightness control 65
`alloWs the brightness of the display 28 to be varied, such that
`the display 28, When operating near its brightest level,
`results in a virtual image that completely blocks that portion
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`8
`of the user’s ?eld of vieW in Which the image is projected.
`By dimming the brightness of the display 28, the virtual
`image appears to be superimposed on the real World in that
`portion of the user’s ?eld of vieW in Which the image is
`projected so that both the image and the real World behind
`the image can be simultaneously seen by the user. By
`completely dimming the display, the virtual image can be
`extinguished from that portion of the user’s ?eld of vieW so
`that the user can see the real World, but the user does not see
`the virtual image at all. It is noted that a WindoW into the real
`World through the displayed image can also be accomplished
`by providing a display Which can be controlled so that light
`does not pass from the display in a de?ned area or WindoW
`thereof. When the light blocking feature of the display is
`actuated, a WindoW into the real World in the area of the
`blocked display light is provided through the displayed
`image, and When not actuated, the image is seen in its
`entirety.
`The binocular optical system shoWn in FIGS. 2—6 auto
`matically compensates for variations in the interpupillary
`distance of different users, Wherein those variations may be
`as great as one inch. More particularly, the system automati
`cally accommodates users having an interpupillary distance
`that is Within a 2—3 inch range. This is accomplished by the
`combination of the prisms 32 and 34 With a concave re?ector
`shoWn as the visor 36. More particularly, the prism in each
`of the right-eye and left-eye optical paths bends light from
`any location along the Width, W, of the prism representing
`various positi