United States Patent (19)
`Hewlett
`
`USOO58284.85A
`Patent Number:
`11
`(45) Date of Patent:
`
`5,828,485
`Oct. 27, 1998
`
`54 PROGRAMMABLE LIGHT BEAM SHAPE
`ALTERING DEVICE USING
`PROGRAMMABLE MICROMIRRORS
`
`75 Inventor: William E. Hewlett, Sutton Coldfield,
`England
`
`73 Assignee: Light & Sound Design Ltd.,
`Birmingham, England
`
`21 Appl. No.: 598,077
`22 Filed:
`Feb. 7, 1996
`(51) Int. Cl." ..................................................... GO2B 26/00
`52 U.S. Cl. ........................... 359/291; 359/223; 35.9/850
`58 Field of Search ..................................... 359/223, 224,
`359/290, 291, 295, 846, 849, 850, 855
`
`56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`5,406,176
`5,452,024
`5,467.146
`5,583,688
`5,647.662
`
`4/1995
`9/1995
`11/1995
`12/1996
`7/1997
`
`Sugden .................................... 315/292
`Sampsell ................................. 348/755
`Huang et al. ........................... 348/743
`Hornbeck ................................ 359/291
`Ziegler et al. .......................... 362/294
`
`Primary Examiner-Georgia Y. Epps
`Assistant Examiner Dawn-Marie Bey
`Attorney, Agent, or Firm Fish & Richardson P.C.
`57
`ABSTRACT
`A digital micromirror device (“DMD) is used to alter the
`shape of light that is projected onto a stage. The DMD
`Selectively reflects Some light, thereby shaping the light that
`is projected onto the Stage. The control for the alteration is
`controlled by an image. That image can be processed,
`thereby carrying out image processing effects on the shape
`of the light that is displayed. One preferred application
`follows the shape of the performer and illuminates the
`performer using a shape that adaptively follows the per
`former's image. This results in a shadowleSS follow spot.
`
`4,947,302 8/1990 Callahan ................................. 362/233
`5,231,388 7/1993 Stoltz ...................................... 340/701
`
`22 Claims, 10 Drawing Sheets
`
`
`
`IMAGE
`PROCESSOR
`
`520
`
`NV
`MEMORY
`
`IMAGE
`SOURCE
`
`
`
`FORMAT
`CONVERTER
`
`MEMORY
`
`
`
`
`
`
`
`
`
`
`
`VWGoA EX1036
`U.S. Patent No. 9,955,551
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 1 of 10
`
`5,828,485
`
`CONDUCTING
`SUPPORT LAYER
`
`TORSION BEAM
`
`TORSION HINGE
`
`
`
`
`
`LANDING
`ELECTRODE
`
`SPACER
`
`SILICON
`SUBSTRATE
`ADDRESS
`ELECTRODE
`
`DEFLECTED PIXEL
`
`
`
`SNAs SA NAAAAYear
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 2 of 10
`
`5,828,485
`
`W
`
`310
`
`t
`t
`335-
`/
`322-N
`CN,
`325 Z
`DMD
`320
`
`305
`
`R
`
`
`
`334
`
`HEAT
`SINK
`
`23. LAMP/REFLECTOR
`SNitor
`? 320
`DISKS
`332
`
`325 y
`I
`
`W
`
`,
`
`COOLNG
`
`FIG. 3
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 3 of 10
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`5,828,485
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`
`
`ON
`
`SOURCE
`
`sustate/
`
`FIG. 4
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 4 of 10
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`5,828,485
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`IMAGE
`PROCESSOR
`
`520
`
`NV
`MEMORY
`
`MAGE
`SOURCE
`
`
`
`FORMAT
`CONVERTER
`
`MEMORY
`
`
`
`
`
`
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet S of 10
`
`5,828,485
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`EDGE
`PROCESSOR
`
`DUTY
`CYCLE
`
`
`
`602
`
`
`
`IMAGE
`PROCESSOR
`
`DEFINE
`OP
`ROTATE
`POSITION SHIFT
`
`DEFINE
`TIME
`ORVELOCITY
`
`
`
`100 PIXEL
`SLCE
`
`
`
`604
`
`
`
`606
`
`
`
`
`
`
`
`608
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`
`
`610
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`
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`
`
`
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`TIME = 100 PIXELS / SLICE
`WPIXELS / SEC
`-o-
`VDIRECTION
`
`TIME:
`RE-CALCULATE IMAGE
`
`PROJECT
`NEW IMAGE
`
`
`
`
`
`FIG. 6
`
`

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`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 6 of 10
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`5,828,485
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`700
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`702
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`704
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`
`
`EDGE PROCESSOR
`
`
`
`
`
`
`
`GET IMAGE
`DEFINE OUTLINE
`
`STRETCHOUTLINE
`
`FOR OUTLINE TO STRETCH
`FILL WITH GRAYSCALE
`
`705
`
`TO MEMORY
`
`FIG. 7
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 7 of 10
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`5,828,485
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`8101
`
`
`
`8110
`
`
`
`
`
`OBTAIN IMAGE OF
`PERFORMER AS KERNEL
`
`OBTAIN
`SCHEME
`
`CORRELATE
`AGAINST KERNEL
`
`FIG. 8B
`
`8001
`
`LOCATE PERFORMER
`NIMAGE
`
`
`
`FOLLOW CHANGING
`BORDER SHAPE
`
`FIG. 8A
`
`

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`U.S. Patent
`
`Oct. 27, 1998
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`Sheet 8 of 10
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`5,828,485
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`800
`
`802
`
`804
`
`806
`\
`
`808
`
`
`
`
`
`OBTAINPERFORMER
`IMAGE ZERO
`
`BEGIN
`FRAME UPDATE
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`ACOUIRE
`IMAGE
`
`PERFORMER IMAGE
`IMAGE ZERO
`
`ANALYZE IMAGE CORRELATE
`AGAINST PERF CHAR
`OBTAIN MAGE OF PERF ONLY
`810
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`
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`812
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`
`
`814
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`DIGITIZE
`
`PROCESS
`
`TRANSFER
`TOVRAM
`
`FIG. 8C
`
`

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`U.S. Patent
`U.S. Patent
`
`Oct. 27, 1998
`Oct. 27, 1998
`
`Sheet 9 of 10
`Sheet 9 of 10
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`5,828,485
`5,828,485
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`
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`FIG. 9A
`FIG. 9A
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`950
`950
`
`954
`
`954
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`[
`
`-902
`oe
`952
`
`952
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`

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`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 10 of 10
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`5,828,485
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`
`
`1032
`
`MEMORY
`
`DIGITIZE
`
`FIG 10
`
`

`

`1
`PROGRAMMABLE LIGHT BEAM SHAPE
`ALTERING DEVICE USING
`PROGRAMMABLE MICROMIRRORS
`
`5,828,485
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`2
`However, any Selectively-controllable multiple-reflecting
`element could be used for this purpose. These Special optics
`are used to create the desired image using an array of
`small-sized mirrors which are movably positioned. The
`micromirrors are arranged in an array that will define the
`eventual image. The resolution of the image is limited by the
`Size of the micromirrors: here 17 um on a Side.
`The mirrors are movable between a first position in which
`the light is directed onto the field of a projection lens System,
`or a Second position in which the light is deflected away
`from the projection lens System. The light deflected away
`from the lens will appear as a dark point in the resulting
`image on the illuminated object. The heat problem is mini
`mized according to the present invention Since the micro
`mirrors reflect the unwanted light rather than absorbing it.
`The absorbed heat is caused by the quantum imperfections
`of the mirror and any gaps between the mirrors.
`A digital micromirror integrated circuit is currently manu
`factured by Texas Instruments Inc., Dallas, TeX., and is
`described in “an overview of Texas Instrument digital micro
`mirror device (DMD) and its application to projection
`displays”. This application note describes using a digital
`micromirror device in a television System. Red, green and
`blue as well as intensity grey Scales are obtained in this
`System by modulating the micromirror device at very high
`rates of Speed. The inventor recognized that this would
`operate perfectly to accomplish his objectives.
`It is hence an object of the present invention to adapt Such
`a device which has Small-sized movable, digitally control
`lable mirrors which have positions that can be changed
`relative to one another, to use as a light beam shape altering
`device in this stage lighting System.
`It is another object of the present invention to use Such a
`System for previously unheard-of applications. These appli
`cations include active simulation of hard or Soft beam edges
`on the gobo. It is yet another application of the present
`invention to allow gobo cross-fading using time control,
`Special effects and morphing.
`It is yet another object of the present invention to form a
`Stroboscopic effect with variable Speed and intensity in a
`Stage lighting System. This includes Simulation of a flower
`strobe.
`Yet another object of the present invention is to provide a
`multiple colored gobo System which can have split colors
`and rotating colors.
`It is yet another object of the present invention to carry out
`gobo rotation in Software, and to allow absolute position and
`Velocity control of the gobo rotation using a time slicing
`technique.
`Another objective is to allow concentric-shaped images
`and unsupported images.
`It is yet another object of the invention to provide a
`control system for the micromirror devices which allows
`Such operation.
`Yet another particularly preferred System is a shadowleSS
`follow Spot, which forms an illuminating beam which is
`roughly of the same shape as the performer, and more
`preferably precisely the same as the performer. The beam
`shape of the beam Spot also tracks the performer's current
`outline. The spot light follows the performer as it lights the
`performer. This action could be performed manually by an
`operator or via an automated tracking System, Such as
`Wybron's autopilot.
`Since the beam does not overlap the performer's body
`outline, it does not cast a shadow of the performer.
`
`FIELD OF THE INVENTION
`The present invention relates to a programmable light
`beam Shaping device. More specifically, the present inven
`tion teaches a control System and micromirror device which
`can alter the shape of light beams passing therethrough, and
`provide various effects to those shaped light beams.
`BACKGROUND OF THE INVENTION
`It is known in the art to shape a light beam. This has
`typically been done using an element known as a gobo. A
`gobo element is usually embodied as either a shutter or an
`15
`etched mask. The gobo shapes the light beam like a stencil
`in the projected light.
`Gobos are simple on/off devices: they allow part of the
`light beam to pass, and block other parts to prevent those
`other parts from passing. Hence mechanical gobos are very
`Simple devices. Modern laser-etched gobOS go a step further
`by providing a gray Scale effect.
`Typically multiple different gobo shapes are obtained by
`placing the gobos are placed into a cassette or the like which
`is rotated to select between the different gobos. The gobos
`themselves can also be rotated within the cassette, using the
`techniques, for example, described in U.S. Pat. Nos. 5,113,
`332 and 4,891,738.
`All of these techniques, have the drawback that only a
`limited number of gobo shapes can be provided. These gobo
`shapes must be defined in advance. There is no capability to
`provide any kind of gray Scale in the System. The resolution
`of the system is also limited by the resolution of the
`machining. This System allows no way to Switch gradually
`between different gobo shapes. In addition, moving between
`one gobo and another is limited by the maximum possible
`mechanical motion Speed of the gobo-moving element.
`Various patents and literature have Suggested using a
`liquid crystal as a gobo. For example, U.S. Pat. No. 5,282,
`121 describes Such a liquid crystal device. Our own pending
`patent application also So Suggests. However, no practical
`liquid crystal element of this type has ever been developed.
`The extremely high temperatures caused by blocking Some
`of this high intensity beam produce enormous amounts of
`heat. The projection gate Sometimes must block beams with
`intensities in excess of 10,000 lumens and sometimes as
`high as 2000 watts. The above-discussed patent applications
`discuss various techniques of heat handling. However,
`because the light energy is passed through a liquid crystal
`array, Some of the energy must inevitably be Stored by the
`liquid crystal. Liquid crystal is not inherently capable of
`Storing Such heat, and the phases of the liquid crystal, in
`practice, may be destabilized by Such heat. The amount of
`cooling required, therefore, has made this an impractical
`task. Research continues on how to accomplish this task
`more practically.
`It is an object of the present invention to obviate this
`problem by providing a digital light beam shape altering
`device, e.g. a gobo, which operates completely differently
`than any previous device. Specifically, this device embodies
`the inventor's understanding that many of the heat problems
`in Such a System are obviated if the light beam shape altering
`device would Selectively deflect, instead of blocking, the
`undesired light.
`The preferred mode of the present invention uses a
`digitally-controlled micromirror Semiconductor device.
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`3
`BRIEF DESCRIPTION OF THE DRAWINGS
`These and other objects will be readily understood with
`reference to the accompanying drawings, in which:
`FIG. 1 shows a single pixel mirror element of the pre
`ferred mode, in its first position;
`FIG. 2 shows the mirror element in its second position;
`FIG.3 shows the mirror assembly of the present invention
`and its associated optics,
`FIG. 4 shows more detail about the reflection carried out
`by the DMD of the present invention;
`FIG. 5 shows a block diagram of the control electronics
`of the present invention;
`FIG. 6 shows a flowchart of a typical operation of the
`present invention;
`FIG. 7 shows a flowchart of operation of edge effects
`operations,
`FIG. 8A shows a flowchart of a first technique of follow
`ing a performer on Stage,
`FIG. 8B shows a flowchart of a correlation Scheme;
`FIG. 8C shows a flowchart of another correlation Scheme;
`FIG. 9 shows a block diagram of a color projection system
`of the present invention;
`FIG.9Ashows a color wheel of the present invention; and
`FIG. 10 shows a block diagram of the shadowless follow
`Spot embodiment.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`The preferred embodiment herein begins with a brief
`description of controllable mirror devices, and the way in
`which the currently-manufactured devices operate.
`Work on semiconductor-based devices which tune the
`characteristics of light passing therethrough has been ongo
`ing since the 1970's. There are two kinds of known digital
`micromirror devices. A first type was originally called the
`formal membrane display. This first type used a Silicon
`membrane that was covered with a metalized polymer
`membrane. The metalized polymer membrane operated as a
`mirror.
`A capacitor or other element was located below the
`metalized element. When the capacitor was energized, it
`attracted the polymer membrane and changed the direction
`of the resulting reflection.
`More modern elements, however, use an electroStatically
`deflected mirror which changes in position in a different
`way. The mirror of the present invention, developed and
`available from Texas Instruments, Inc. uses an aluminum
`mirror which is Sputter-deposited directly onto a wafer.
`The individual mirrors are shown in FIG. 1. Each indi
`vidual mirror includes a square mirror plate 100 formed of
`reflective aluminum cantilevered on hollow aluminum post
`102 on flexible aluminum beams. Each of these mirrors 100
`have two stop positions: a landing electrode, which allows
`them to arrive into a first position shown in FIG. 2, and
`another electrode against which the mirror rests when in its
`non-deflected position. These mirrors are digital devices in
`the sense that there two “allowable' positions are either in
`a first position which reflects light to the lens and hence to
`the illuminated object, and a Second position where the light
`is reflected to a Scattered position. Light Scattering (i.e.
`selective light reflection) of this type could also be done with
`other means, i.e. Selectively polarizable polymers,
`electronically-controlled holograms, light valves, or any
`other means.
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`The operation of the dark field projection optics which is
`used according to the preferred micromirror device is shown
`in FIG. 3. The two bi-stable positions of the preferred
`devices are preferably plus or minus 10% from the horizon
`tal.
`An incoming illumination bundle 303 is incident at an arc
`of less than 20 on the digital micromirror device 220. The
`illumination bounces off the mirrors in one of two directions
`230 or 232 depending on the mirror position. In the first
`direction 302, the position we call “on”, the information is
`transmitted in the 0 direction 300 towards lens 302 which
`focuses the information to the desired location 304. In the
`second direction of the mirror, the position we call “off”, the
`information is deflected away from the desired location to
`the direction 306.
`The human eye cannot perceive actions faster than about
`/30 Second. Importantly, the mirror transit time from tilted
`left to tilted right is on the order of 10 us. This allows the
`pixels to be changed in operation many orders of magnitude
`faster than the human eye's persistence of vision.
`Light Source 310 used according to the present invention
`is preferably a high intensity light Source Such as a Xenon or
`metal halide bulb of between 600 and 1000 watts. The bulb
`is preferably surrounded by a reflector of the parabolic or
`ellipsoidal type which directs the output from bulb 300
`along a first optical incidence path 305.
`The preferred embodiment of the invention provides a
`color cross-fading system 315, such as described in my U.S.
`Pat. No. 5,426,476. Alternately, however, any other color
`changing System could be used. This cross-fading System
`adjusts the color of the light. The light intensity may also be
`controlled using any kind of associated dimmer; either
`electronic, mechanical or electromechanical means. More
`preferably, the DMD 320 could be used to control beam
`intensity as described herein.
`The light beam projected 310 along path 305 is incident
`to the digital light altering device embodied as DMD 320, at
`point 322. The DMD allows operations between two differ
`ent states. When the mirror in the DMD is pointed to the
`right, the right beam is reflected along path 325 to
`projection/Zoom lens combination 330, 332. The Zoom lens
`combination 330, 332 is used to project the image from the
`DMD 320 onto the object of illumination, preferably a stage.
`The size and Sharpness quality of the image can therefore be
`adjusted by repositioning of the lens. When the mirror is
`tilted to the right, the light beam is projected along the light
`path 335, away from projection lens 330/332. The pixels
`which have light beams projected away from the lens appear
`as dark points in the resulting image. The dark spots are not
`displayed on the Stage.
`This DMD system reflects information from all pixels.
`Hence, minimal energy is absorbed in the DMD itself or any
`of the other optics. The device still may get hot, however not
`nearly as hot as the liquid crystal gobOS. Cooling 325 may
`still be necessary. The DMDs can be cooled using a heat sink
`and convection, or by blowing cold air from a refrigeration
`unit across the device. More preferably, a hot or cool mirror
`can be used in the path of the light beam to reflect infrared
`out of the light beam to minimize the transmitted heat. FIG.
`3 shows hot mirror 330 reflecting infrared 332 to heat sink
`334. A cold mirror would be used with a folded optical path.
`This basic System allows Selecting a particular aperture
`shape with which to which pass the light. That shape is then
`defined in terms of pixels, and these pixels are mapped to
`DMD 320. The DMD selectively reflects light of the
`properly-shaped aperture onto the Stage. The rest of the light
`is reflected away, e.g. to a heat Sink.
`
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`The micromirror can be switched between its positions in
`approximately 10 us. A normal time for frame refresh rate,
`which takes into account human persistence of vision, is
`/60th of a second or 60 hertz. Various effects can be carried
`out by modulating the intensity of each mirror pixel within
`that time frame.
`The monolithic integration which is being formed by
`Texas Instruments includes associated row and column
`decoders thereon. Accordingly, the System of the present
`invention need not include those as part of its control
`System.
`Detailed operation of DMD 320 is shown in FIG. 4. The
`Source beam is input to the position 322 which transmits the
`information either towards the Stage along path 325 or away
`from the stage along path 335.
`The various effects which are usable according to the
`present invention include automatic intensity dimming, use
`of a “shadowless follow spot”, hard or soft beam edges,
`Shutter cut Simulation, gobo croSS fading, gobo Special
`effects, Stroboscopic effects, color gobOS, rotating gobos
`including absolute position and Velocity control, and other
`Such effects and combinations thereof. All of these effects
`can be controlled by Software running on the processor
`device. Importantly, the characteristics of the projected
`beam (gobo shape, color etc) can be controlled by Software.
`This enables any software effect which could be done to any
`image of any image format to be done to the light beam. The
`Software that is used is preferably image processing Software
`such as Adobe photoshop TM Kai's power tools TM or the like
`which are used to manipulate images. Any kind of image
`manipulation can be mapped to the Screen. Each incremental
`changes to the image can be mapped to the Screen as it
`OCCS.
`Another important feature of the gobo is its ability to
`project unconnected Shapes that cannot be formed by a
`Stencil. An example is two concentric circles. A concentric
`circle gobo needs physical connection between the circles.
`Other unconnected Shapes which are capable of rendering as
`an image can also be displayed.
`The effects carried out by the Software are grouped into
`three different categories: an edge effects processing, an
`image shape processing; and a duty cycle processing.
`The overall control System is shown in block diagram
`form in FIG. 5. Microprocessor 500 operates based on a
`program which executes, inter alia, the flowchart of FIG. 6.
`The light shape altering operates according to a stencil
`outline. This stencil outline can be any image or image
`portion. An image from image Source 552 is input to a
`format converter 552 which converts the image from its
`native form into digital image that is comparable with
`Storage on a computer. The preferred digital image formats
`include a bitmap format or compressed bitmap form Such as
`the GIF, JPEG, PCX format (1 bit per pixel) file, a “BMP"
`file (8 bits/pixel B/W or 24 bits/pixel color) or a geometric
`description (vectorized image). Moving images could also
`be sent in any animation format such as MPEG or the like.
`It should be understood that any image representation format
`could be used to represent the image, and that any of these
`representations can be used to create information that can
`modify reflecting positions of the array of reflecting devices.
`The present specification uses the term “digital representa
`tion' to generically refer to any of these formats that can be
`used to represent an image, and are manipulable by com
`puters.
`65
`Image 554 is input into a working memory 556. BMP
`format represents each “pixel’ picture element of the image
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`by a number of bits. A typical gray Scale bit map image has
`8 bits representing each pixel. A colored image of this type
`has 8 bits representing each of red, green, and blue repre
`Sentations. This color representation is called a 24-bit
`representation, Since 24-bits are necessary for each pixel.
`The description herein will be given with reference to gray
`Scale images although it should be understood that this
`System can also be used with color images by forming more
`detailed maps of the information. Bit maps are easiest to
`process, but extremely wasteful of Storage space.
`Each memory area, representing each pixel, therefore, has
`8 bits therein. The memory 556 is 576x768 area, corre
`sponding to the number of mirror elements in the preferred
`Sc.
`This image is defined as image No. X, and can be Stored
`in non-volatile memory 520 (e.g., flash RAM or hard disk)
`for later recall therefrom. An important feature of the present
`invention is that the images are Stored electronically, and
`hence these images can also be electronically processed in
`real time using image processing Software. Since the pre
`ferred mode of the present invention manipulates the image
`information in bitmap form, this image processing can be
`carried out in a very quick Succession.
`The image to be projected is sent, by processor 500, over
`channel 560, to VRAM 570. Line driver 562 and line
`receiver 564 buffer the signal at both ends. The channel can
`be a local bus inside the lamp unit, or can be a transmission
`line, Such as a Serial bus. The image information can be sent
`in any of the forms described above.
`Standard and commonly available image processing Soft
`ware is available to carry out many functions described
`herein. These include for example, morphing, rotating,
`Scaling, edge blurring, and other operations that are
`described herein. Commercial image processing can use
`“Kai's Power Tools”, “CorelDraw!", or “Morph Studio” for
`example. These functions are shown with reference to the
`flowchart of FIG. 6.
`Step 600 represents the system determining the kind of
`operation which has been requested: between edge
`processing, image processing, and duty cycle processing.
`The image processing operations will be defined first.
`Briefly Stated, the image processing operations include
`rotation of the image, image morphing from image 1 to
`image 2, dynamic control of image shape and Special effects.
`Each of these processing elements can Select the Speed of the
`processing to effectively time-slice the image. The morphing
`of the present invention preferably Synchronizes keyframes
`of the morph with desired time slices.
`Step 602 defines the operation. As described above, this
`operation can include rotation, position shift, and the like.
`Step 604 defines the time or velocity of operation. This time
`can be ending time for all or part of the movement, or
`velocity of the movement. Note that all of the effects carried
`out in Step 602 require moving Some part of the image from
`one position to another.
`Step 606 determine the interval of slicing, depending on
`the Velocity. It is desireable to Slice an appropriate amount
`Such that the user does not see jerky motion. Ideally, in fact,
`we could slice movement of the image one pixel at a time,
`but this is probably unnecessary for most applications. One
`hundred pixel Slicing is probably Sufficient for all applica
`tions. The pixel slices are selected at step 606.
`Step 608 calculates using the time or velocity entered at
`step 604 to determine the necessary time for operation based
`on the amount of position shift for rotation over 100 pixel
`slices. This is done as follows. Position shift, rotate, and
`
`

`

`7
`Sprite animation are all simple movements. In both, the
`points of the image which define the gobo Shape move over
`time. It is important, therefore, to decide how much move
`ment there is and how much time that movement will take.
`A rate of change of points or Velocity is then calculated. Of
`course Velocity need not be calculated if it has already been
`entered at step 604.
`Having Velocity of movement and pixels per Second, the
`time between Slices is calculated using 100 pixels per Slice
`divided by the velocity in pixels per second. The direction of
`movement is defined by this operation.
`Therefore, the image is recalculated at step 610 for each
`time interval. This new image becomes the new gobo Stencil
`at the new location. That is to Say, the outline of the image
`is preferably used as the gobo-light within the image is
`passed, and light outside the image is blocked. In the color
`embodiment described herein, more Sophisticated opera
`tions can be carried out on the image. For example, this is
`not limited to Stencil images, and could include for example
`concentric circles or letter text with font Selection.
`At any particular time, the image in the VRAM 570 is
`used as the gobo Stencil. This is carried out as follows. Each
`element in the image is a gray Scale of 8-bits. Each /60th of
`a second is time-sliced into 256 different periods. Quite
`conveniently, the 8-bit pixel image corresponds to 2=256.
`A pixel value of 1 indicates that light at the position of the
`pixel will be shown on the Stage. A pixel value of Zero
`indicates that light at the position of the pixel will not be
`shown on the Stage. Any gray Scale value means that only
`part of the intensity pixel will be shown (for only part of the
`time of the v6oth of a second time slice). Hence, each
`element in the memory is applied to one pixel of the DMD,
`e.g. one or many micromirrors, to display that one pixel on
`the Stage.
`When edge processing is selected at step 600, control
`passes to the flowchart of FIG. 7. The edge graying can be
`Selected as either a gradual edge graying or a more abrupt
`edge graying. This includes one area of total light, one area
`of only partial light, and one area of no light. The intensity
`of the gray Scaled outline is continuously graded from full
`image transmission to no image transmission. The intensity
`variation is effected by adjusting the duty cycle of the on and
`off times.
`Step 700 obtains the image and defines its outlines. This
`is carried out according to the present invention by deter
`mining the boundary point between light transmitting por
`tions (1’s) and light blocking portions (0's). The outline is
`stretched in all directions at step 702 to form a larger but
`concentric image-a stretched image.
`The area between the original image and the Stretched
`image is filled with desired gray scale information. Step 704
`carries this out for all points which are between the outline
`and the Stretch image.
`This new image is sent to memory 570 at step 706. As
`described above, the image in the memory is always used to
`project the image-shaped information. This uses Standard
`display technology whereby the display System is continu
`ally updated using data Stored in the memory.
`The duty cycle processing in the flowchart of FIG. 6 is
`used to form strobe effects and/or to adjust intensity. In both
`cases, the image is Stored in memory and removed from
`memory at periodic intervals. This operation prevents any
`light from being projected toward the Stage at those
`intervals, and is hence referred to as masking. When the
`image is masked, all values in the memory become Zero, and
`hence this projects all black toward the Source. This is done
`
`15
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`8
`for a time which is shorter than persistence of vision, So the
`information cannot be perceived by the human eye. Persis
`tence of vision averages the total light impinging on the
`Scene. The eye hence Sees the duty cycle processing as a
`different intensity.
`The stroboscopic effect turns on and off the intensity,
`ranging from about 1 Hz to 24 Hz. This produces a strobe
`effect.
`These and other image processing operations can be
`carried out: (1) in each projection lamp based on a prestored
`or downloaded command; (2) in a main processing console;
`or (3) in both.
`Another important aspect of the invention is based on the
`inventor's recognition of a problem that has existed in the art
`of Stage lighting. Specifically, when a performer is on the
`Stage, a Spotlight illuminates the performer's area. However,
`the inventor of the present invention recognized a problem
`in doing this. Specifically, Since we want to see the
`performer, we must illuminate the performer's area.
`However, when we illuminate outside the performer's area,
`it casts a shadow on the Stage behind the performer. In many
`circumstances, this shadow is undesirable.
`It is an object of this embodiment to illuminate an area of
`the Stage confined to the performer, without illuminating any
`location outside of the performer's area. This is accom
`plished according to the present invention by advantageous
`processing Structure which forms a “shadowleSS follow
`spot'. This is done using the basic block diagram of FIG. 10.
`The preferred hardware is shown in FIG. 10. Processor
`1020 carries out the operations explained with reference to
`the following flowcharts which define different ways of
`following the performer. In all of these embodiments, the
`shape of the performer on the Stage is determined. This can
`be done by (1) determining the performer's shape by Some
`means, e.g. manual, and following that shape; (2) correlating
`over the image looking for a human body shape; (3) infrared
`detection of the performer's location followed by expanding
`that location to the shape of the performer; (4) image
`Subtraction; (5) detection of Special indices on the
`performer, e.g. an ultraSonic beacon, or, any other technique
`even manual following of the image by, for example, an
`operator following the performer's location on a Screen
`using a mouse.
`FIG. 8A shows a flowchart of (1) above. At step 8001, the
`performer is located within the image. The camera taking the
`image is preferably located at the lamp illuminating the
`Scene in order to avoid parallax. The image can be manually
`investigated at each lamp or downloaded to Some central
`processor for this purpose.
`Once identified, the borders of the performer are found at
`8005. Those borders are identified, for example, by abrupt
`color changes near the identified point. At step 8010, those
`changes are used to define a “stencil outline that is slightly
`smaller than the performer at 8010. That stencil outline is
`ued as a gobo for the light at 8015.
`The performer continues to move, and at 8020 the pro
`ceSSor follows the changing border shape. The changing
`border shape produce