EXHIBIT 2184
`
`EXHIBIT 2184EXHIBIT 2184
`
`
`
`

`
`United States Patent [19]
`Liptoh et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,792,850
`Dec. 20, 1988
`
`[54]
`
`[75]
`
`METHOD AND SYSTEM EMPLOYING A
`PUSH-PULL LIQUID CRYSTAL
`MODULATOR
`Inventors: Lenny Liptoh, Greenbrae; Arthur
`Berman, San Jose; Lawrence D.
`Meyer, Mill Valley; James L.
`Fergason, Atheyton, all of Calif.
`SteroGraphics Corporation, San
`Rafael, Calif.
`Appl. No.: 125,402
`Nov. 25, 1987
`Filed:
`Int. Cl.'
`U.S. Cl.
`
`[73] Assignee:
`
`HO4N 13/04
`358/92; 350/132;
`553/8; 358/88
`358/88, 92, 3; 350/130,
`350/132; 353/8
`
`[58] Field of Search
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`2,099,694 3/1934 Land .
`8/1941 Reynolds .
`2,417,446
`3,256,776 6/1966 Land
`3,858,001 12/1974 Bonne .
`4,021,846 5/1977 Roese .
`7/1981 Hyatt .
`4,281,341
`4,385,806 5/1983 Fergason
`4,436,376 3/1984 Fergason .
`4,523,226 6/1985 Lipton et al. .
`9/1985 Fergason .
`4,540,243
`4,562,463 12/1985 Lipton .
`4,582,396 4/1986 Bos et al. .
`4,583,825 4/1986 Buzak .
`4,698,668 10/1987 Milgram
`4,709,263 11/1987 Brumage
`4,719,482 1/1988 Hora
`4,719,507 1/1988 Bos
`4,736,246 4/1988 Nishikawa
`FOREIGN PATENT DOCUMENTS
`3607629A1 10/1986 Fed. Rep. of Germany .
`52-110516 3/1976 Japan .
`
`358/3
`
`358/92
`358/88
`358/92
`358/88
`358/92
`
`53-80114 7/1978 Japan .
`61-250613 11/1986 Japan .
`2175171A 11/1986 United Kingdom .
`OTHER PUBLICATIONS
`"Compatible 3-D Television: The State of the Art" by
`Balasubramonian, et al.
`"Three-Dimensional Projection with Circular Polariz-
`ers: "by V. Walworth, et al.
`"Use of Strong Surface Alignment in Nematic Liquid
`Crystals for High Speed Light Modulation" by James
`L. Fergason.
`"A Liquid-Crystal Video Stereoscope with High Ex-
`tinction Ratios, A 28% Transmission State and One-
`Hundred-Microsecond Switching" by Thomas J. Ha-
`ven.
`"On the Merits of Bicircular PolarizatiOn for Stereo
`Color TV" by K. Balasubramonian et al.
`Hartmann, et al., "Three-Dimension TV with Cordless
`FLC Spectacles," Information Display, Oct. 1987, pp.
`15-17.
`Pn'mary ExaminerHoward W. Britton
`Attorney, Agent, or FirmLimbach, Limbach & Sutton
`ABSTRACT
`[57]
`A system and method employing a push-pull modulator
`for stereoscopic image selection. The modulator in-
`cludes a pair of surface mode liquid crystal cells having
`orthogonal rub axes, and a linear polarizer having ab-
`sorption axis bisecting the orthogonal rub axes, and has
`high speed, good transmission, and symmetrical dy-
`namic range characteristics. A field-sequential stero-
`scopic video image may be transmitted from a video
`display screen (or video projector) through the modula-
`tor as the cells of thc modulator are driven so that fields
`of altemately left-handed circularly polarized light and
`right-handed circularly polarized light will emerge.
`The transmitted circularly polarized light may be
`viewed using passive spectacles incorporating circular
`polarizing filters.
`
`31 Claims, 5 Drawing Sheets
`
`Masterlmage 3D, Inc. and Masterlmage 3D Asia, LLC - Exhibit 1004
`
`REALD INC.
`Exhibit 2184-1
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`U.S. Patent
`
`Dec. 20, 19
`
`Sheet 1 of 5
`
`4,792,850
`
`(PRIOR ART)
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`Master' sd_
`
`Inc. and Masterlmage 3D Asia, LLC - Exhibit 1004
`
`REALD INC.
`Exhibit 2184-2
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`U.S. Patent
`
`Dec. 20, 1988
`
`Sheet 2 of 5
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`4,792,850
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`Masterlmage 3D, Inc. and 1111
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`11WIrgeft Asia, LLC - Exhibit 1004
`
`REALD INC.
`Exhibit 2184-3
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`U.S. Patent
`
`Dec. 20, 1988
`
`Sheet 3 of 5
`
`4,792,850
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`Masterlmage 3D, Inc. and Masterlmage 3D Asia, LLC - Exhibit 1004
`
`REALD INC.
`Exhibit 2184-4
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`U.S. Patent
`
`Dec. 20, 1988
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`Masterlmage 3D, Inc. and Masterlmage 3D Asia, LLC - Exhibit 1004
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`REALD INC.
`Exhibit 2184-5
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`U.S. Patent
`
`Dec. 20, 1988
`
`Sheet 5 of 5
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`Masterlmage 3D, Inc. and Masterlmage 3D Asia, LLC - Exhibit 1004
`
`REALD INC.
`Exhibit 2184-6
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`4,792,850
`
`1
`
`2
`polarizer is employed at the CRT (cathode ray tube)
`screen with active elements (Kerr Cells) and passive
`METHOD AND SYSTEM EMPLOYING A
`PUSH-PULL LIQUID CRYSTAL MODULATOR
`sheet linear polarizers at each eye.
`Conventional video display systems employing on-
`FIELD OF THE INVENTION
`5 screen modulation typically include a video screen cov-
`ered by a sheet linear polarizer and an electrooptical
`This invention relates generally to liquid crystal cell
`variable halfwave retarder celL Each observer wears
`systems that may be electrically driven to transmit light
`linear polarizin' g spectacles to view light transmitted
`having alternating circular polarization states. The in-
`from the screen through the linear polarizer and half-
`vention relates more particularly to stereoscopic video
`display systems that include surface mode liquid crystal 10 wave retarder cell. The halfwave cell is typically liquid
`crystal (LC) cell that is switched from an isotropic state
`cells that are driven so as to transmit sequentially right-
`(at high potential) to a birefringent state (at low paten-
`circularly polarized light and left-circularly polarized
`tial) at field rate. If the axis of the onscreen linear polar-
`light comprising the fields of a field-sequential image.
`izer is at 45 degrees to the optical axis of the variable
`BACKGROUND OF THE INVENTION
`15 halfwave retarder, then the plane of polarized light
`Stereoscopic video display systems that display a
`exiting the retarder and visible to the observer will have
`field-sequential image have been described in U.S. Pat.
`its axis alternating between orthogonal states with each
`Nos. 4,523,226, issued June 11, 1985 to Lipton, and in
`successive field. Hence, linear polarizers mounted with
`4,562,463, issued Dec. 31, 1985 to Lipton.
`orthogonal axes for the left and right lenses in the spec-
`In one version of this type of display system (de- 20 tides alternately occlude or transmit the appropriate
`scribed in U.S. Pat. No. 4,562,463 with reference to
`image.
`FIGS. 1-3) an observer views a display screen through
`Such conventional systems thus employ a liquid crys-
`powered electro-optical shutters (elements 15 and 16 of
`tal suutter including first and second linear polarizers
`U.S. Pat. No. 4,562,03) which are synchronized with
`whose axes are orthogonal, vvith a liquid crystal cell
`the field-sequential image at the field rate. However, use 25 interposed between the polarizers, and with the axis of
`of such active occluding shuttets has a number of draw-
`the cell bisecting the polarizer axes. In the shutter's
`backs. The active shutters must be synchronized with
`transmissive state, low voltage is applied to the cell, so
`the field-sequential display by cable or wireless trans-
`that the cell is a uniaxial birefringent crystal which
`mission means so the shutters will open and close at
`resolves the incident wave into two orthogonal compo-
`field rate. Since each shutter is open only half of the 30 nent waves of linear polarized light, polarized parallel
`time, when viewing the environment surrounding the
`and perpendicular to the principal axis, respectively.
`display, such as printed material, the ambient lllumina-
`The rate of propagation of light through the crystal is
`don is reduced by the duty cycle, i.e., by a factor of two.
`different for the two component waves. In passing
`In addition, in the transmissive state, conventional ac-
`through the halfwave retarder, the fast wave is retarded
`tive electro-optical shutters impose the attenuarion of 35
`180° less than the slow wave is retarded. The vector
`two sheet linear polarizers with parallel axes in front of
`sum of the emerging fast and slow electric vectors re-
`each eye. If another video display is used a disturbing
`sults in a reflection about the principal axis of the initial
`"roll bar" will be seen, since the shutters may not be
`polarization vector. If the initial polarization angle was
`synchronized to the field rate of another display.
`On the other hand, the use of what we call "onscreen 40 45 degrees, the reflection is equivalent to a rotation of
`the polarization angle by 90 degrees.
`modulation" systems has also been proposed. Such sys-
`In the shutter's occluded state, characterized by high
`tems employ a large electro-optical polarization switch-
`voltage, the electric vectors of an incoming wave are
`ing device, which covers the display screen and alters
`not rotated, and the liquid crystal cell is in an isotropic
`the polarization characteristic of the transmitted light at
`field rate, with passive selection devices including sheet 45 state. In this state, the index of refracrion of the liquid
`crystal material is the same in every direction, and there
`polarizers that have no intrinsic duty cycle. In this type
`is no retardation effect.
`of onscreen modulation system, the brightness of the
`However, conventional onscreen modulation systems
`environment surrounding the display is reduced only by
`the attenuation of a single polarizing sheet. Moreover,
`employing passive sheet linear polarizers to view trans-
`there will be no "roll bar" artifact when looking at 50 mitted light from a video screen have the following
`other, =synchronized video displays.
`disadvantage. Because of the law of Mains (described,
`U.S. Pat. Nos. 3,858,001, issued Dec. 31, 1974 to
`for example, in Fundamental of Optics, Fourth Edition,
`Bonne; 4,281,341, issued July 28, 1981 to Byatt; Japa-
`Jenkins and White, McGraw-Hill, 1976), head-tiPPing
`nese Patent Application (Kokai) No. 52-110516 by
`of only a few degrees by the viewer vvill lead to an
`Fujita; and above-mentioned U.S. Pat. No. 4,562,463 55 unacceptable increase in image crosstalk. The law of
`(with reference to FIG. 4 thereof) have suggested the Mains relates the intensity I of linear polarized light
`use of onscreen modulation techniques employing a
`transmitted by a linear analyzer, to the intensity If, of the
`large liquid crystal cell which alters the characteristic
`incident linear polarized light, and the angle b between
`of polarized light at field rate, in which the observer
`the plane of the axis of incident polarized light and the
`views the display screen through passive eyeglasses 60 plane of the axis of the analyzer, by the expression:
`with sheet linear polarizer filters. Together the modula-
`i=i0,00, 2b.
`tor and sheet polarizers in the glasses form a shutter for
`image selection for a field sequential stereoscopic video
`display.
`Thus, a small change in the angle b will result in a large
`We can also fmd an early reference to a related con- 65 change in transmission. Accordingly, only a little head
`cept by Reynolds, who, in U.S. Pat. No. 2,417,446,
`tipping leads to the perception of the unwanted images
`by the eyes when viewing through linear polarizing
`issued Mar. 19, 1947, suggests using a Kerr Cell for a
`variable retarder. In Reynolds' concept, a sheet linear
`spectacles.
`
`Masterlmage 3D, Inc. and Masterlmage 3D Asia, LLC - Exhibit 1004
`
`REALD INC.
`Exhibit 2184-7
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`4,792,850
`
`3
`In spite of the greatly improved environmental image
`brightness, the convenience, and the lighter weight of
`the passive spectacles compared with active shuttering
`goggles, for many applications it may be unacceptable
`to require that the viewees head remain rather rigidly 5
`in place while observing the image.
`If circular, rather than linear, polarized light could be
`employed, then polarizer extinction would not be angu-
`larly dependent, and head-tipping would not produce
`ghosting, as suggested by Land in U.S. Pat. No. IO
`2,099,694, issued Nov. 23, 1937 (at page 2, left column,
`lines 62-68). In the case of circularly polarized light, the
`Law of Mains does not apply. Given a source of inci-
`dent circularly polarized light of one handedness, and a
`circular polarizer analyzer of the opposite handedness, 15
`the transmitted intensity of light remains substantially
`constant with rotation of the analyzer with respect to
`the incident light. Accordingly, the unwanted field
`remains occluded from view.
`However, conventional large liquid crystal cell 20
`(LLCC) devices are unsuitable for producing circular
`polarized light of the type suitable for use in a stereo-
`scopic video display system.
`For example, we believe that it is disadvantageous to
`employ a conventional LLCC in conjunction with a 25
`linear polarizer as described above, in combination with
`a conventional quarter-wave retarder as suggested in
`"Compatible 3-D Television: tbe State of the Art," by
`Balasubramonian, et al. in SPIE, Volume 402, 1983 (pp.
`100-106). FIG. 1 illustrates this conventional approach. 30
`Video monitor lis fed a video signal from video source
`5 via cable 6. CRT (or similar display screen) 2 is
`viewed by an observer through a linear polarizer 3, and
`LLCC half-wave retarder 4 (also referred to as LLCC
`4). LLCC 4 is powered by controller 8 via cable 9. 35
`Controller 8 senses vertical synchronization pulses of
`video source 5 via cable 7 and uses these sync pulses to
`trigger LLCC 4, which varies optically from the iso-
`tropic to birefringent condition at video field rate.
`Quarter-wave retarder 13 is placed in front of LUC 4. 40
`The absorption axis of polarizer 3 is oriented at 45 de-
`grees to the rub axis of LLCC 4, and the fast optical axis
`of retarder 13 must be parallel to the rub axis of LLCC
`4. Linear polarizer 3, LLCC 4, and quarter-wave re-
`tarder 13 are in intimate juxtaposition and mounted in 45
`front of CRT screen 2. Analyzing spectacles 10 with
`circular polarizing filters 11 and 12 are used for viewing
`the image. An example of a commercially available
`LLCC of the type that may be use in the FIG. 1 system
`is the "pi-cer having 12 inch diagonal, manufactured 50
`by Tektronix, Inc. Tbe disadvantages of the FIG. 1
`arrangement will be discussed below.
`In FIG. 2, we show a similar disadvantageous con-
`ventional approach for producing circular polarized
`light in a stereoscopic video display system. All ele- 55
`metas of the FIG. 2 system are the same as those in
`FIG. 1, except that quarter-wave retarder 13 has been
`removed, and linear polarizer 3 has been replaced by
`conventional circular polarizer 14. The axis of the linear
`polarizer portion of circular polarizer 14 is oriented at 60
`45 degrees to the rub axis of LLCC 4.
`The observer views screen 2 through circular polar-
`izer 14 and LLCC 4, which are in intimate juxtaposition
`and mounted at the screen, using glasses 10, which have
`circular polarizer analyzers of opposite handedness 11 65
`and 12. Elements 1, 2, and 5 may be replaced by a suit-
`able motion picture projector, and LLCC 4 driven at
`the appropriate motion picture field rate (determined by
`
`4
`the projector speed and the length of each field segment
`on the film), in a conventional variation on the FIG. 2
`system.
`Circular polarizers commercially available from Po-
`laroid Corporation (having product designation
`HN37CP), or similar circular polarizers, were used for
`projection of stereoscopic films in a few motion picture
`theaters in 1983. A motion picture projection system
`using such a circular polarizer is described in Three-Di-
`mensional Projection with Circular Polarizer, by Wal-
`worth, et al., SPIE, Vol.462, Optics in Entertainment II
`(1984), pp.64-68.
`The Polaroid circular polarizer consists of a sheet
`linear polarizer and a quarter-wave retarder bonded
`together with 45 degrees between their axes. In the
`FIG. 2 system, the sheet linear polarizer side of circular
`polarizer 14 faces CRT 2, and the quarter-wave retarder
`side faces LLCC 4. Light from the phosphor of CRT 2
`passes through circular polarizer 14, and then through
`LLCC 4. The light output is circular polarized light,
`alternately left-handed and right-handed, as LLCC 4 is
`switched at the field rate.
`Our experiments have shown that commercially
`available LLCC's, though available with diagonals of
`12 inches or more, do not have adequate performance
`with respect to dynamic range and decay time (the time
`in which the shutter changes from its transraissive to its
`occluded state for a stereoscopic selection device appli-
`cation. The dynamic range of a shutter is defined as the
`ratio of its transminion in its on state to its transmission
`in its off state. For a 12 inch pi-cell manufactured by
`Tektronix used with the FIG. 1 and FIG. 2 systems
`described above, we have measured a dynamic range
`for one eye about fifty percent greater than for the other
`eye, that is 12:1 for one eye, and 8:1 for the other. More-
`over, for either eye, the dynamic range of either of these
`conventional systems is unacceptably low. An equal
`dynanaic range for each eye of many times the figures
`given above, is necessary for acceptable results. The
`result of the measured low add asymmetric dynamic
`range is an observed doubling or "ghosting" of the
`displayed image produced by either conventional sys-
`tem, because inadequate occlusion of the unwanted
`image leads to crosstalk.
`In addition, althoug the present surface mode
`LLCC's (such as the Tektronix 12 inch diagonal pi-cell)
`have a fairly rapid rise time (the time in which the shut-
`ter changes from it occluded to its transmissive state),
`they have a slow decay time. The rise time and decay
`time are less than 1 millisecond and about 2 millisec-
`onds, respectively. This asymmetry presents pooblems
`for a stereoscopic display since a portion of one set of
`fields (either the right or left) may show partial occlu-
`sion or discoloration as a result The asymmetrical na-
`tures of the dynamic range and rise and decay times are
`closely related, and inherent in the construction of the
`conventional LLCCs. Since the vertical blanking inter-
`val of a raster scan video or computer graphics display
`is on the order of one millisecond, considerable im-
`provement in speed is needed.
`The asymmetrical nature of the dynamic range for
`the left and right eye arises from the fact that in the case
`of one eye, the analyzer (spectacle) axis must be perpen-
`dicular to the linear polarizer axis at the modulator, and
`the other eye must see through an analyzer with an axis
`oriented parallel with respect to the modulator polar-
`izer linear axis. For the perpendicular case, the dynamic
`range is higher than for the parallel case.
`
`Masterlmage 3D, Inc. and Masterlmage 3D Asia, LLC - Exhibit 1004
`
`REALD INC.
`Exhibit 2184-8
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`4,792,850
`
`6
`5
`In order for an on-screen switching device to pro-
`sequential stereoscopic video projector has been outfit-
`ted svith a push-pull modulator.
`duce an acceptable stereoscopic display, rise and decay
`FIG. 7 is a graph with voltage on the vertical axis and
`time must be substantially the same and within the verti-
`cal blanking interval for a raster display. (Even faster
`time on the horizontal axis) of two driving signals, each
`5 of the type that may be used to drive one cell of the
`rise and decay times are demanded by vector displays.)
`push-pull modulator of the inventive system.
`Moreover, the dynamic range must be substantially the
`FIG. 8 is a graph (with voltage on the vertical axis
`same for both eyes, and the dynamic range must be
`and time on the horizontal axis) of another driving sig-
`many times greater than presently available from com-
`nal for driving one cell of the push-pull modulator of
`mercial LLCC's. Until the present invention, it was not
`10 the inventive system.
`known how to achieve these desired characteristics.
`FIG. 9 is a graph (with voltage on the vertical axis
`SUMMARY OF THE INV ENT ION
`and time on the horizontal axis) of yet another driving
`The invention includes an electro-optical modulator
`signal for driving one cell of the push-pull modulator of
`of the type disclosed as a communications device by
`the inventive system.
`FIG. 10 is a pair of graphs (each with voltage on the
`Fergason in U.S. Pat. Nos. 4,540,243, issued Sept. 10, 15
`vertical axis and time on the horizontal axis), showing a
`1985, and in 4,436,376, issued Mar. 13, 1984. l'his modu-
`preferred embodiment of two driving signals for driv-
`lator, which is known as a push-pull modulator, uses
`ing the two cells of the inventive push-pull modulator.
`surface mode liquid crystal cells of a construction de-
`FIG. 11 is a pair of graphs showing an alternative
`scribed by Fergason in U.S. Pat. No. 4,385,806, issued
`May 31, 1983. The construction of the push-pull modu- 20 version of the driving signals of FIG. 10.
`lator is as follows: Two surface mode liquid crystal cells
`DETAILED DESCRIPTION OF THE
`whose rub axes are orthogonal are placed together in
`PREFERRED EMBODIMENTS
`intimate juxtaposition with a linear polarizer whose
`FIG. 3 is a schematic representation of a preferred
`absorption axis bisects the orthogonal rub axes of the
`two aforementioned cells. The order of the parts is as 25 embodiment of the present invention. Video signal
`follows: linear polarizer, and the two liquid crystal
`source 5 outputs a field-sequential stereoscopic image,
`such as that described in U.S. Pat. Nos. 4,523,226, or
`cells.
`4,562,463, to monitor 1, which may be a CRT unit or
`In the inventive system, the cells are driven electri-
`cally out of phase (so that when one cell is in a high
`any kind of electronic video display. A push-pull modu-
`voltage state, the other is in a low voltage state, and vice 30 lator including linear polarizer 3 and liquid crystal cells
`versa). When driven appropriately and positioned in
`15 and 16 is placed in front of monitor l's display screen
`2. Liquid crystal cells 15 and 16 are of a construction
`front of a cathode ray or similar display unit (svith the
`first described by Fergason in U.S. Pat. No. 4,385,806.
`linear polarizer nearest the screen), and when the driver
`of the push-pull modulator is synchronized with the
`Cells 15 and 16 are surface mode liquid crystal cells
`field rate of the CRT display unit, the light transmitted 35 which are fast acting, compared to the usual twisted
`from the display unit through the push-pull modulator
`nematic liquid crystal device. Cells 15 and 16 are driven
`by driver 17, which drives cells 15 and 16 electrically
`will be left-handed circular polarized light, alternating
`with right-handed circular polarized light at the field
`out of phase so that when cell 15 is at high potential, cell
`rate. When viewed through spectacles including left
`16 is at low potential. Driver 17 is preferably of the type
`and right handed circular polarianr analyzers, half of 40 to be described below with reference to FIGS. 7-9.
`Alternatively, driver 17 may be of any commercially
`the fields of the field-sequential display will be transmit-
`available type having the characteristics described be-
`ted to one eye and half to the other eye, thus providing
`an appropriate selection mechanism for a stereoscopic
`low. Driver 17 is connected to cells 15 and 16 via cables
`9 and 9'.
`field-sequential video display.
`Driver 17 observes the sync pulses of the video signal
`BRIEF DESCRIPTION OF THE DRAWINGS
`output by. source 5, and triggers the drive voltages to
`FIG. 1 is a schematic representation of a conven-
`cells 15 and 16 in synchronization with the sync pulses
`tional system for producing circular polarized light in a
`so that the polarized light emerging from cells 15 and 16
`will be in synchronization with the video fields pro-
`field sequential stereoscopic video display.
`FIG. 2 is a schematic representation of an alternative 50 duced by source 5. Conventional video signals include
`conventional system for producing circular polarized
`sync pulses of the type suitable for this purpose.
`light in a field sequential stereoscopic video display.
`FIG. 4 is a preferred embodiment of a push-pull mod-
`FIG. 3 is a schematic representation of a preferred
`ulator (identified by reference numeral 35), to be posi-
`embodiment of the disclosed invention in which a field-
`tioned in front of screen 2 to serve the function of linear
`sequential stereoscopic video display has its light output 55 polarizer 3 of FIG. 3 and surface mode liquid crystal
`modulated by a push-pull modulator that includes two
`cells 15 and 16 of FIG. 3. Unit 35 includes linear polar-
`surface mode LLCC's and a linear polarizer whose axis
`izer 34, transparent plates 36, 37, and 38, and collar 42
`bisects the mutually orthogonal rub axes of the two
`for housing elements 36, 37, 38, and 43. Central plate 38
`sufface mode LLCC's.
`is coated by transparent electrical coating 39 on both of
`FIG. 4 is a cross-sectional view of a preferred em- 60 its surfaces. Plates 36 and 37 are each coated vvith a
`bodiment of a push-pull liquid crystal modulator of the
`layer of transparent electrical coating 39 on their inner
`type used in the inventive system.
`surfaces. Layers 40 and 41 of liquid crystal material are
`FIG. Sis a schematic representation of the axes of the
`sandwiched between plates 36 and 38, and 37 and 38,
`linear polarizer and LLCC's used in the construction of
`respectively. Electrical conductors 43 and 44 of cable 9
`a push-pull modulator of the type included in the inven- 65 provide electrical bias across liquid crystal layer 41, and
`conductors 45 and 46 of cable 9' provide electrical bias
`rive system.
`across liquid crystal layer 40. An electrical driving
`FIG. 6 is a schematic representation of another pre-
`ferred embodiment of the invention, in which a field-
`signal may be applied across conductor pair 43,44 and
`
`45
`
`Masterlmage 3D, Inc. and Masterlmage 3D Asia, LLC - Exhibit 1004
`
`REALD INC.
`Exhibit 2184-9
`MASTERIMAGE 3D, et al. v REALD INC.
`IPR2015-00035
`
`

`
`4,792,850
`
`25
`
`7
`8
`when screen 2 is covered by the push-pull modulator
`across conductor pair 45,46, superimposed upon the
`comprising parts 3, 15, and 16. The voltages output by
`electrical bias. On the inner surfaces of each coating 39
`(which coating may be, for example, an alloy of tin
`the drivers of unit 17 are adjusted until maximum dy-
`oxide and indium oxide) is a coating whose surface
`namic range is attained. The point of maximum dynamic
`range may be determined visually, or by photometric
`molecules are aligned using an appropriate alignment 5
`means. The polarized light beam from linear polarizer 3
`technique, such as uniaxial nibbing of a polyvinyl alco-
`is transmitted through each of the two liquid crystal
`hol coating or an angular evaporation technique. Plate
`cells 15 and 16, each of which introduces its own inde-
`37, layer 40, the left half of plate 38, and the coating 39
`pendent phase shift into the light beam emerging from
`sandwiched therebetween correspond collectively to
`cell 16 of FIG. 3. Plate 36, layer 41, the right half of 10
`linear polarizer 3. The phase shifts vectorially combine
`so that the two liquid crystal cells 15 and 16 function
`plate 38, and the coating 39 therebetween correspond to
`vvith respect to the light beam in a manner analogous to
`cell 15 of FIG. 3. Collar 42 need not be included, where
`the other elements of the modulator are laminated to-
`the functioning of a push-pull amplifier acting upon an
`gether. In a variation on the FIG. 4 system, plate 38
`oscillatory electrical signal. As a consequence, the re-
`may be replaced by two plates, each plate comprising 15
`tardation of the resulting phase-shifted light is substan-
`part of a different liquid crystal cell of the push-pull
`tially greater than would be produced absent one of the
`modulator.
`cells.
`FIG. 5 shows the relationship of the various axes of
`In one embodiment, a driving signal having the wave-
`form of signal 100 of FIG. 7 may be used to drive a
`linear polarizer 3 and liquid crystal cells 15 and 16. Line
`modulator that includes a pair of cells each having
`3 represents the absorption axis of linear polarizer 3, 20
`thickness in the range 5 microns to 7 microns, and in-
`and lines 15' and 16' represent the alignment, or slow,
`cludes liquid crystal fluid from E. Merck, Part No.
`axes of cells 15 and 16. Axes 15' and 16' are orthogonal,
`ZLI-1646. Signal 100 is a 2 kHz carrier wave modulated
`and linear polarizer axis 3' makes a 45 degree angle with
`by square waves having period T. We achieve maxi-
`axis 15' and with axis 16'. In other words, axis 3' bisects
`mum dynamic range for the shutters used in our experi-
`the right angle made by axes 15' and 16'.
`ments, when the square wave modulating signal has
`When cells 15 and 16 are driven electrically out of
`lower peak-to-peak voltage L substantially equal to 6
`phase by driver 17, so that when one has a high voltage
`volts for its lower voltage portions, and has higher
`the other has a low voltage, given the configurations
`peak-to-peak voltage H substantially equal to (or
`shown in FIGS. 3 and 5, circularly polarized light,
`greater than) 40 volts for its higher voltage portions.
`alternately left-handed and right-handed, will be trans- 30
`mitted at the field rate. Driver 17 has its voltages set for
`For inventive shutters employing typical, commercially
`the construction and materials of the particular cells
`available components, the signals preferably will have
`lower peak-to-peak voltage in the range zero to 10
`used as elements 15 and 16. In one embodiment, driver
`volts, and will preferably have higher peak-to-peak
`17 will output (through each of cables 9 and 9') an AC
`voltage in the range 40 to 80 volts. The liquid crystal
`carrier wave (typically a 2 ICHz carrier wave), modu- 35
`cells employed will preferably have thickness in the
`lated by a square wave. In a preferred embodiment (to
`be described below with reference to FIGS. 7-10), the
`range 5 microns to 7 microns.
`driver vvill output carrier-less waves whose time-
`It is conventional to employ a 2 KHz carrier for the
`driving signal for conventional surface mode liquid
`averaged voltage is substantially equal to zero. The
`signal transmitted through cable 9 (in both the embodi- 40
`crystal cells. The purpose for using this frequency is to
`ment employing an AC carrier wave and the embodi-
`avoid electro-chemical reactions within the cells. The
`inner walls of the glass chambers of the cells immedi-
`ment employing a carrier-less wave) will be electrically
`out of phase with respect to the signal transiitted
`ately adjacent to the liquid crystal fluid are coated with
`a conductor. If the AC carrier wave is removed, some
`through cable 9'. Typically the peak-to-peak amplitude
`have argued that ion migration from one conductor
`of the low voltage portion of the modulated AC driving 45
`signal will be between zero and ten volts, and the peak-
`wall to the other vrill take place, thefeby rendering the
`to-peak amplitude of the high voltage portion will be a
`cell inoperative.
`Experiments we have performed demonstrate that
`few tens of volts. Also typically, the square wave driv-
`ing signal will include low voltage square wave por-
`cell performance is indeed greatly diminished if the cells
`are driven without using an AC carrier, but instead
`tions (having peak-to-peak amplitude between zero and 50
`ten volts) alternating with high voltage square wave
`using a square wave which is either above or below
`grourid. However, we have discovered that a carrier-
`portions (having peak-to-peak amplitude equal to a few
`tens of volts).
`less driving signal (such as one having the waveform of
`When cell 15 is at low potential, cell 16 is at high
`signal 101 of FIG. 7) which is equally above and below
`potential, and vice versa. When one of the dual and 55
`ground, with a net voltage of zero averaged over time,
`will produce no reduction in the cell's performance
`coordinated drivers of unit 17 (driver unit 17 will some-
`relative to the cell's performance when an AC carrier
`times be referred to as having a driver for each of cables
`9 and 9') is switched from high to low voltage, the other
`having frequency of order of magnitude several kHz is
`driver voltage is switched from low to high. This
`employed. Signal 101 is essentially the envelope of sig-
`nal 100, and has period T, which will preferably be
`switching takes place simultaneously, and ideally cc- 60
`curs within the vertical blanking interval of the video
`equal to the inverse field rate (i.e., T= (Field rate)-1).
`fields produced by source 5. Driver 17 includes means
`When using a carrier-le