CA1113619A - Interactive projection display system - Google Patents
Interactive projection display systemInfo
- Publication number
- CA1113619A CA1113619A CA307,632A CA307632A CA1113619A CA 1113619 A CA1113619 A CA 1113619A CA 307632 A CA307632 A CA 307632A CA 1113619 A CA1113619 A CA 1113619A
- Authority
- CA
- Canada
- Prior art keywords
- image
- light
- screen
- display system
- crosswire
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
- G06F3/038—Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
- G06F3/0386—Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry for light pen
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Human Computer Interaction (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Projection Apparatus (AREA)
- Position Input By Displaying (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
INTERACTIVE PROJECTION DISPLAY SYSTEM
Abstract of the Disclosure An interactive projection display system having a light pen device for use thereon is described. The projection display system has an image of a light valve on a projection screen which is formed by visible light of specified wavelengths. The projection screen also has a translatable crosswire image thereon which is formed by radiation which includes the visible light used to form the light valve image and an additional spectral component. The light pen device is sensitive to this additional spectral component. In a preferred embodiment, the image of the light valve and the cross-wires are formed with white light (0.3 to 0.7 microns).
The additional spectral component used for the crosswire image and the light pen sensing is a band of near-IR
radiation (0.7 to 1 micron).
Abstract of the Disclosure An interactive projection display system having a light pen device for use thereon is described. The projection display system has an image of a light valve on a projection screen which is formed by visible light of specified wavelengths. The projection screen also has a translatable crosswire image thereon which is formed by radiation which includes the visible light used to form the light valve image and an additional spectral component. The light pen device is sensitive to this additional spectral component. In a preferred embodiment, the image of the light valve and the cross-wires are formed with white light (0.3 to 0.7 microns).
The additional spectral component used for the crosswire image and the light pen sensing is a band of near-IR
radiation (0.7 to 1 micron).
Description
13 ~ielcl of the In~entlon ~___ _ _ _ 19 Thls invention relates to interacti~e pr~,jection dis~la~ s~sterils and rnore particularly t,o a sy_ em suitahle 21 for havirlcJ a light pen device used there~ith.
22 _scri~tion of the_Prl _ Art 23 Some projec-tion display sys-tems are inter~ctive, 24 that is, they permit operator selection of control options from a large library of available options. Interactive 26 projection display sys-tems generally employ a selection 27 means and/or a position indicator. A keyboarc, con-trol 28 lever or a stylus-type device, for example a light pen, 29 are commonly used selec-tor means. A cursor is an example of a position indicator.
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1 All inter~ctive projection display system using a light
22 _scri~tion of the_Prl _ Art 23 Some projec-tion display sys-tems are inter~ctive, 24 that is, they permit operator selection of control options from a large library of available options. Interactive 26 projection display sys-tems generally employ a selection 27 means and/or a position indicator. A keyboarc, con-trol 28 lever or a stylus-type device, for example a light pen, 29 are commonly used selec-tor means. A cursor is an example of a position indicator.
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1 All inter~ctive projection display system using a light
2 pen device is describecl in the patent to
3 ~orthington et al, USP 3,825,730. This -two-way projectlon ~ system selects desired lnput messayes from a library of selectable messages by locatiny the posi-tion of the light 6 emitting light pen with an array of photodetectors. This 7 system is limited -to opera-tion in a read only mode as well 8 as to a fixed number of options which is de-termined by g the number of detectors in the array.
The stylus Eunction for use as a graphie input is 11 described in -the patent to Ellis e-t al, USP 3,399,401 12 where the user interaets directly wi-th a tablet separate 13 and distinc-t from the display screen. Since the system 14 does not deal direc-tly with the display screen, it needs to correlate the tablet with the display screen.
16 The cursor function in a data input generator is described 17 in the patent to Heartz, USP 3,883,861 and is used for 18 eneoding information in a digital form to produce a data 19 base descriptive of a land mass or the like. This system does not utilize a light pen func-tion and requires a beamsplitter 21 whieh would prohibit the use of a light pen function 22 whieh would touch the screen.
23 Stylus devices which are used to indicate eoordinates 24 directly on -the display screen fall into two basic categories.
The first type acts independently of the image on the sereen 26 such as the aeoustic stylus device described in U.S. Patent 27 3,692,936 (Moffitt 9/19/72). The seeond type, of whieh the 28 CRT light pen is the most common example, uses a photo-29 responsive stylus which senses the photo emission from the display screen. ~he coordinates of the light pen are -~
1 determined Erom timincJ information using the fact that the 2 screen image is being reEreshed (periodically rewritten) at 3 a rapid rate. This basic light pen systern has two limi-tations:
The stylus Eunction for use as a graphie input is 11 described in -the patent to Ellis e-t al, USP 3,399,401 12 where the user interaets directly wi-th a tablet separate 13 and distinc-t from the display screen. Since the system 14 does not deal direc-tly with the display screen, it needs to correlate the tablet with the display screen.
16 The cursor function in a data input generator is described 17 in the patent to Heartz, USP 3,883,861 and is used for 18 eneoding information in a digital form to produce a data 19 base descriptive of a land mass or the like. This system does not utilize a light pen func-tion and requires a beamsplitter 21 whieh would prohibit the use of a light pen function 22 whieh would touch the screen.
23 Stylus devices which are used to indicate eoordinates 24 directly on -the display screen fall into two basic categories.
The first type acts independently of the image on the sereen 26 such as the aeoustic stylus device described in U.S. Patent 27 3,692,936 (Moffitt 9/19/72). The seeond type, of whieh the 28 CRT light pen is the most common example, uses a photo-29 responsive stylus which senses the photo emission from the display screen. ~he coordinates of the light pen are -~
1 determined Erom timincJ information using the fact that the 2 screen image is being reEreshed (periodically rewritten) at 3 a rapid rate. This basic light pen systern has two limi-tations:
4 it cannot operate with a storage type or long persistence display, and i-t can only detect in luminous areas of the 6 screen. The first limi-tation is circumvented by the paten-t ; 7 to Davis, U.S. Patent 4,020,281 in which a storage display 8 is partially erased and rewritten during the light pen g operation. The second limitation is circumvented by several means which employ the writing o~ a special luminous pattern 11 on the screen during the light pen operation, as referenced 12 in the aforementioned Davis patent.
~ 13 Summary of the Invention ;;: 14 It is a primary object of this invention to provide an ,:
improved interactive projection display system.
16 It is another object of this invention to provide means 17 for interacting with the projected image upon a screen.
18 It is still another object of this invention to provide 19 an interactive projection display system having a light pen function which is not restricted to predetermined portions 21 of the display field.
22 It is still another object of this invention to provide 23 an interactive projection display system having a light pen 24 function which can detect on both written and unwritten -portions of -the display field.
26 It is yet still another object of this invention 27 to provide an interactive projection display system having 28 a light pen function which interacts directly with the 29 projec-tion screen.
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i 1 It is a ~urtller object oE this invention to provide an 2 interactive projection display system havincJ both a light 3 pen function and a cursor function.
4 These and other objects are accomplished by an interactive projection display sys-tem which has an image 6 of a llght valve on a projection screen formed by visible 7 light of specified wavelengths, and which has a translatable 8 crosswire image on the projection screen formed by radia-tion g which includes the visible light used to form -the light valve image and an additional spectral component. This 11 additional spectral componen-t is an arbitrary wavelength 12 band, and is preferably generated by the projection lamp.
13 The system also has a light pen device sensitive to this additional spectral component which when used in conjunction with a translatable crosswire lmage senses the light pen 16 position on the screen. In a preferred embodiment, the image OL the light valve and the crosswires are formed with white 18 light (0.3 -to 0.7 microns). The additional spectral component 19 used for the crosswire image and the light pen sensing is a band of near-IR radiation (0.7 to 1 micron). The cursor 21 function is provided by the visible image of the crosswires 22 on the projection screen. The intersection of the images 23 of the two wires indicates the reference coordinates on the 24 screen. In the light pen mode, the horizontal and vertical images of the cursor wires are translated rapidly across the 26 screen in succession. The light pen device when activated 27 in a conventional manner detects the passage of the image of 28 the wires formed in the near IR band. The position of the 29 light pen is determined by knowledge of the position of the cursor wires at the tirne the images are detected.
1 Other ob]ects oE this invention will be apparen-t from the following de-tailed description, reference being made -to the accompanying drawings wherein various embodiments of the invention are shown.
~rief Description of the Drawings _ .. . ... .. _ Fig. 1 is a schematic view of the interactive projec-tion display system of this invention.
Fig. 2 illustrates a typical light spectrum for a projection lamp utilized in this invention.
lo Fig. 3 located on the same page as Fig. 1, is a top view of the cursor arrangement.
Fig. 4 is a cross-sectional view of the light pen - device.
Fig. 5 illustrates the interaction of the light pen and the cursor function.
Fig. 6, located on the same page as Fig. 2 is a schematic view of the interactive display system in ~- accordance with this invention.
Fig. 7 is a schematic of a second embodiment of this inventiOn.
Description of the Illustrative Embodiments This invention deals with an interactive projection display system as shown in Fig~ 1. The interactive system has a projection system 10 which projects an image from a light valve (not shown) on a rear projection screen 12. On the screen 12 are images 14 and 16 of the cursor wires which -' intersect each other at point 18 as the crosswire image to indicate the reference coordinates on the screen 12 and thereby provide the cursor function. A light pen 20 has an end 22 which interacts directly with the projection screen 20. During operation of the light pen 20, the images 14 and 16 of the cursor wires are translated rapidly across the 3~ 3 1 screen 12 in succession. ~ctivation of the light pen 20 in 2 a conventional manner de-tects -the passage of the image 14 3 and 16 of the cursor wires by the light pen device being , 4 sensitive to the additional spectral component which is used to form the cursor wire images 14 and 16 as will hereinafter 6 be more fully discussed. The position of the light pen end ~ 7 22 on the screen 12 is determined by knowledge of the posi-tion ,~ 8 f the cursor wire images 14 and 16 at -the time the images 9 14 and 16 are intercep-ted as will hereinafter be more fully discussed.
11 The cursor wires will be opaque to the radiation and `~ 12 hence their images 14 and 16 on the screen will always be 13 black. The light valve (LV) may be either subtractive or 14 additive. With a subtractive LV, the screen will normally . 15 be luminous and written areas of the image will be darker.
' 16 With an additive LV, the screen will normally be dark and 17 written areas of the image will be luminous. In either 18 case, the dark areas of the screen image will not be black 19 because of the limited contrast ratio of the image.
Thus, the crosswire image 18 will be visible at all - 21 points of the screen and in principle it could be detected 22 by a light pen device 20 sensitive to the visible spectrum.
23 However, the signal level would vary widely from dark to 24 luminous areas of the screen, and hence it is preferable to flood the cursor wires uniformly with an additional spectral 26 component which is dis-tinct from the visible light used to 27 form the image of the LV.
28 The light or radiation output from the projection 29 system 10 is critical for the successful operation of the cursor wire images and the light pen device and can be more ' .
1 readily und~rstoocl by describlllc3 the radiation in the framework 2 set ~orth in Fiy. 2. Typically, a lamp of the type used in 3 projection clisplay systems has an output which covers the spectrum shown in Fig. 2, that is, it has UV liyht haviny wavelengths less than 0.4 microns, visible liyht in the 6 ran~e of .4 to .7 microns, near-IR liyht having a wavelength 7 between .7 and about 2.0 microns and IR radiation or heat 8 having a wavelength yreater than about 2 microns. In yeneral, 9 the imaye in the projection display system on the screen is formed with the visible light. This visible liyht is 11 also used to form the image of the cursor wires. In addition, 12 the crosswire image contains an additional spectral component.
13 In the preferred embodiment, this addi-tional spectral componen-t 14 is in the near-IR wavelength, that is, between 0.7 and l.0 microns. The light pen device is only sensitive to this 16 additional spectral component.
17 It should be recognized that the additional spectral 18 component is no-t limited to the near IR band, but could be 19 amony other t'nings a band of visible liyht, for example, red liyht. The LV image could be formed with the remainder of : .
21 the visible spectrum, namely, cyan light. Dark areas of the 22 LV image would appear red and light areas would be white.
23 The ligh-t pen would be made sensitive to red light only.
24 As shown in Fig. 3, the X-cursor is a wire 16A which is connected to motor and encoder means 24. The Y-cursor is a wire 26 14A which is connected to motor and encoder means 26. The mechan-27 ical and electromechanical operation of the X and Y-cursor 28 wires is performed in a conventional manner and other alternative 29 means may be used if desired. The image of the X-cursor wire moves across the screen from left to right or right to 31 left. The image of the Y-cursor wire moves across the 3^ screen from top to bottom or bottom to top.
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~n en:largecl v:iew of the light pen 20~ :i.s shown ln j , 2 Fig. 4. 'I`he light pen 20A has an end 22A which is 3 posi-tionecl d;rectly on -the projection screen. ~Vhen 4 the light pen encl 22A is placed on the screen, the lens 2 images a small area of the screen onto the aperture 26.
6 ~s the image Oe the X-cursor crosswire crosses this area, ~ 7 and passes through filter 28, the ou-tpu-t of the photodiode 30 :~ ~ 8 will momen-tarily dip as shown in Fig. 5. Using the known 9 position of -the X-cursor at this instant (Tl) (~'rom a sha:Et - 10 encoder or by using a stepping mo-tor as is well known in the 11 art), the X-coordina-te Oe the light pen can be found.
~ 12 Immediately following Tl, the Y-cursor can be made to move in :~ 13 order to de-termine the Y-coordinate of the light pen.
14 _ The essential characteristics of the light pen 20A is that the photodiode 30 is responsive to the :~ 16 additional spectral component which is used to form 17 the translatable crosswlre im~age on the projection ~- 18 screen.' The preferred additional ~pectral component 19 is in the near IR spectrum portion~ that is, between 0.7 microns and 1-.0 mlcrons.
21 The interact1on between the light pen and the 22 cursor wire image is more easily understood by a discussion ,~ 23 about Fig. 5. In Fig. 5, the upper curve 34.shows -the 24 output of the photodiode and,the lower curve 36 shows-the.
position of the image O:e the'X-cursor as a function of 26 time. The pos:ition information is provided by a shaft 27 encoder on the motor which drives the X-cursor, or by 28 timing information, or by sim:ilar means. When the image 29 of the X-cursor crosses the position of the light pen at 38, the output 40 of the photodiode will momentarily .
SA977Ql9 -8.-' ' 1 drop. The known posltion of the X-cursor at this time (Tl) 2 is the X-coordinate oE the light pen.
3 Similarly, a subsequent and slrnilar operation of the ~-4 cursor will provide the Y-coordinate of the light pen.
~ preferred embodiment ~or a transmissive LV is shown 6 in Fig. 6. A projec-tion lamp 42 having visible light 44 7 represented by an arrow with a single line, nea~-IR radiation 8 46 represented by an arrow with a double line, and IR
g radiation 48 represented by an arrow with a wavy line.
The radiation 44, 46, and 48 is collimated by the condenser 11 lens 50. The collimated radiation is direc-ted to hot 12 mirror 52 which transmits the visible light 44 and reflects 13 the IR radiation 46 and the near-IR 48~ Radiation 46 and 48 is directed to a special cold mirror 54 which transmits the IR radiation 48 and reflects the near-IR
16 radiation 46 to a condenser lens 56. The near-IR
17 radiation 46 is reflected off of a folding mirror 58 to à
18 hot mirror 60. The visible light 44 which is passed -through 19 the hot mirror 52 passes through a condenser lens 62 and a light valve which is located in plane 64. The visible light 21 then passes -through hot mirror 60 and con~inues along with 22 the near IR radiation 46 to relay lens 66 which relays an 23 image of light valve in plane 64\into the~ plane of the 24 cursor wires located a-t 68. The light then proceeds through a field lens 70 which images the aperture of the relay lens 26 66 into the aperture of the projection lens 72. The pro-27 jection lens 72 images plane 68 onto a screen (not shown.) 28 Hence, the screen displays an image of the LV whose 29 image was relayed into plane ~8 and also àn image of the cursor wires which are located in plane 68.
~A977019 -9_ .~ ' .
1 The ~referred embodiment describecl above in Eig. 6 2 utillzes the near-IR radiatioII as the spec-tral componen-t 3 which passes through the plane 68 to forr,l an image of the 4 cursor wires on a screen which is subsequently sensed by a light pen sensitive to the near IR radia-tion.
6 It is understood that numerous variations of the embodiments shown in Fig. 6 can be used. For example, the 8 mïrror 60 may also be used for directing on to the LV 64 a neàr--IR laser, such as Nd:YAG for the purpose of writing on the LV. It is also understood that ins-tead of using a portion 11 of the lamp spec-trum for the néar-IR, a se?arate narrow 12 bandwidth source could be used. For example, the special 13 cold mirror 54 could be removed and a GaAs IR diode could be 14 put in its place.
Another embodiment suitable for a reflective LV is shown 16 in Fig. 7. A lamp 80 transmits visible light 82, near IR
17 radiation 84 and IR radiation 86 through a condenser lens 88 18 which collimates the light from the lamp 80. The light 19 passes through the condenser lens 89 and forms an image of the lamp filament on an elliptical mirror 90 on the aperture 21 plate 94. The elliptical mirror 90 reflects visible light 22 but transmits IR and near-IR radiation. The aperture plate 23 94 contains an aperture 91 and a front surface mirror 92 on 24 the opposite side of the aperture plate to elliptical mirror 90 Aperture ~late 94 is suitable for a sub-tractlve LV. Altern-26 atively, aperture plate 94A is for an additive LV and has an 27 elliptical mirror 90A, a front surface mirror 92A on the opposite 28 side of the aperture plate to 90A and an opaque stop 93A. The 29 near IR radiation 84 and the IR radiation 86 which passes -through the el:liptical mirror 90A continues and passes SA977019 -1~-~r ~
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1 througl1 con~ellser lerls 96 to a special cold mirror.98 which ; 2 -transmits the IR heat 86 bu-t ref:Lects the near IR radiation ; 3 8~. The near IR ra(iiation 84 that :is refl.ec-ted by the mirror 98 passes through the condenser lens 96 and Eorms.
an image of the lamp filamen-t on mirror 92~
6 The visible light 82 is reflected by mirror 90 (90A) 7 and passes -through a -telecen-tric schlieren lens 100 to a re:flective 8 light valve 102. The rei'lective ligh-t valve 82 reElec-ts 9 visible light 82 through the lens 100 to the aperture 91 on : 10 aperture plate 94 (or a.round the opaque s-top 93A on aperture 11 plate 94). The visible ligh-t 82 and the near IR radiation 12 84 passes.through relay lens 103 which along with lens 100 13 forms an image o:E the light valve 102 in plane 104, the l4 location oE -the cursor wires. Field lens 106 images the aperture of relay lens 103 into the aperture of projection 16 lens 108 which images plane 10 onto a screen not shown.
17 It is understood tha-t the invention could be utilized 18 with an image from a CRT or similar photoemissive display 19 element when used in a projection display mode.
. This invention is particularly useful for projection 21 systems employing a reflective liquid crystal light valve.
22 Although some preferred embodiments of this invention 23 have been described, it is understoo'd that numerous variations 24 may be made in accordance with -the principles of this lnvention.
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~ 13 Summary of the Invention ;;: 14 It is a primary object of this invention to provide an ,:
improved interactive projection display system.
16 It is another object of this invention to provide means 17 for interacting with the projected image upon a screen.
18 It is still another object of this invention to provide 19 an interactive projection display system having a light pen function which is not restricted to predetermined portions 21 of the display field.
22 It is still another object of this invention to provide 23 an interactive projection display system having a light pen 24 function which can detect on both written and unwritten -portions of -the display field.
26 It is yet still another object of this invention 27 to provide an interactive projection display system having 28 a light pen function which interacts directly with the 29 projec-tion screen.
SA977019 ~3~
i 1 It is a ~urtller object oE this invention to provide an 2 interactive projection display system havincJ both a light 3 pen function and a cursor function.
4 These and other objects are accomplished by an interactive projection display sys-tem which has an image 6 of a llght valve on a projection screen formed by visible 7 light of specified wavelengths, and which has a translatable 8 crosswire image on the projection screen formed by radia-tion g which includes the visible light used to form -the light valve image and an additional spectral component. This 11 additional spectral componen-t is an arbitrary wavelength 12 band, and is preferably generated by the projection lamp.
13 The system also has a light pen device sensitive to this additional spectral component which when used in conjunction with a translatable crosswire lmage senses the light pen 16 position on the screen. In a preferred embodiment, the image OL the light valve and the crosswires are formed with white 18 light (0.3 -to 0.7 microns). The additional spectral component 19 used for the crosswire image and the light pen sensing is a band of near-IR radiation (0.7 to 1 micron). The cursor 21 function is provided by the visible image of the crosswires 22 on the projection screen. The intersection of the images 23 of the two wires indicates the reference coordinates on the 24 screen. In the light pen mode, the horizontal and vertical images of the cursor wires are translated rapidly across the 26 screen in succession. The light pen device when activated 27 in a conventional manner detects the passage of the image of 28 the wires formed in the near IR band. The position of the 29 light pen is determined by knowledge of the position of the cursor wires at the tirne the images are detected.
1 Other ob]ects oE this invention will be apparen-t from the following de-tailed description, reference being made -to the accompanying drawings wherein various embodiments of the invention are shown.
~rief Description of the Drawings _ .. . ... .. _ Fig. 1 is a schematic view of the interactive projec-tion display system of this invention.
Fig. 2 illustrates a typical light spectrum for a projection lamp utilized in this invention.
lo Fig. 3 located on the same page as Fig. 1, is a top view of the cursor arrangement.
Fig. 4 is a cross-sectional view of the light pen - device.
Fig. 5 illustrates the interaction of the light pen and the cursor function.
Fig. 6, located on the same page as Fig. 2 is a schematic view of the interactive display system in ~- accordance with this invention.
Fig. 7 is a schematic of a second embodiment of this inventiOn.
Description of the Illustrative Embodiments This invention deals with an interactive projection display system as shown in Fig~ 1. The interactive system has a projection system 10 which projects an image from a light valve (not shown) on a rear projection screen 12. On the screen 12 are images 14 and 16 of the cursor wires which -' intersect each other at point 18 as the crosswire image to indicate the reference coordinates on the screen 12 and thereby provide the cursor function. A light pen 20 has an end 22 which interacts directly with the projection screen 20. During operation of the light pen 20, the images 14 and 16 of the cursor wires are translated rapidly across the 3~ 3 1 screen 12 in succession. ~ctivation of the light pen 20 in 2 a conventional manner de-tects -the passage of the image 14 3 and 16 of the cursor wires by the light pen device being , 4 sensitive to the additional spectral component which is used to form the cursor wire images 14 and 16 as will hereinafter 6 be more fully discussed. The position of the light pen end ~ 7 22 on the screen 12 is determined by knowledge of the posi-tion ,~ 8 f the cursor wire images 14 and 16 at -the time the images 9 14 and 16 are intercep-ted as will hereinafter be more fully discussed.
11 The cursor wires will be opaque to the radiation and `~ 12 hence their images 14 and 16 on the screen will always be 13 black. The light valve (LV) may be either subtractive or 14 additive. With a subtractive LV, the screen will normally . 15 be luminous and written areas of the image will be darker.
' 16 With an additive LV, the screen will normally be dark and 17 written areas of the image will be luminous. In either 18 case, the dark areas of the screen image will not be black 19 because of the limited contrast ratio of the image.
Thus, the crosswire image 18 will be visible at all - 21 points of the screen and in principle it could be detected 22 by a light pen device 20 sensitive to the visible spectrum.
23 However, the signal level would vary widely from dark to 24 luminous areas of the screen, and hence it is preferable to flood the cursor wires uniformly with an additional spectral 26 component which is dis-tinct from the visible light used to 27 form the image of the LV.
28 The light or radiation output from the projection 29 system 10 is critical for the successful operation of the cursor wire images and the light pen device and can be more ' .
1 readily und~rstoocl by describlllc3 the radiation in the framework 2 set ~orth in Fiy. 2. Typically, a lamp of the type used in 3 projection clisplay systems has an output which covers the spectrum shown in Fig. 2, that is, it has UV liyht haviny wavelengths less than 0.4 microns, visible liyht in the 6 ran~e of .4 to .7 microns, near-IR liyht having a wavelength 7 between .7 and about 2.0 microns and IR radiation or heat 8 having a wavelength yreater than about 2 microns. In yeneral, 9 the imaye in the projection display system on the screen is formed with the visible light. This visible liyht is 11 also used to form the image of the cursor wires. In addition, 12 the crosswire image contains an additional spectral component.
13 In the preferred embodiment, this addi-tional spectral componen-t 14 is in the near-IR wavelength, that is, between 0.7 and l.0 microns. The light pen device is only sensitive to this 16 additional spectral component.
17 It should be recognized that the additional spectral 18 component is no-t limited to the near IR band, but could be 19 amony other t'nings a band of visible liyht, for example, red liyht. The LV image could be formed with the remainder of : .
21 the visible spectrum, namely, cyan light. Dark areas of the 22 LV image would appear red and light areas would be white.
23 The ligh-t pen would be made sensitive to red light only.
24 As shown in Fig. 3, the X-cursor is a wire 16A which is connected to motor and encoder means 24. The Y-cursor is a wire 26 14A which is connected to motor and encoder means 26. The mechan-27 ical and electromechanical operation of the X and Y-cursor 28 wires is performed in a conventional manner and other alternative 29 means may be used if desired. The image of the X-cursor wire moves across the screen from left to right or right to 31 left. The image of the Y-cursor wire moves across the 3^ screen from top to bottom or bottom to top.
SA977019 _7_ ' .
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~n en:largecl v:iew of the light pen 20~ :i.s shown ln j , 2 Fig. 4. 'I`he light pen 20A has an end 22A which is 3 posi-tionecl d;rectly on -the projection screen. ~Vhen 4 the light pen encl 22A is placed on the screen, the lens 2 images a small area of the screen onto the aperture 26.
6 ~s the image Oe the X-cursor crosswire crosses this area, ~ 7 and passes through filter 28, the ou-tpu-t of the photodiode 30 :~ ~ 8 will momen-tarily dip as shown in Fig. 5. Using the known 9 position of -the X-cursor at this instant (Tl) (~'rom a sha:Et - 10 encoder or by using a stepping mo-tor as is well known in the 11 art), the X-coordina-te Oe the light pen can be found.
~ 12 Immediately following Tl, the Y-cursor can be made to move in :~ 13 order to de-termine the Y-coordinate of the light pen.
14 _ The essential characteristics of the light pen 20A is that the photodiode 30 is responsive to the :~ 16 additional spectral component which is used to form 17 the translatable crosswlre im~age on the projection ~- 18 screen.' The preferred additional ~pectral component 19 is in the near IR spectrum portion~ that is, between 0.7 microns and 1-.0 mlcrons.
21 The interact1on between the light pen and the 22 cursor wire image is more easily understood by a discussion ,~ 23 about Fig. 5. In Fig. 5, the upper curve 34.shows -the 24 output of the photodiode and,the lower curve 36 shows-the.
position of the image O:e the'X-cursor as a function of 26 time. The pos:ition information is provided by a shaft 27 encoder on the motor which drives the X-cursor, or by 28 timing information, or by sim:ilar means. When the image 29 of the X-cursor crosses the position of the light pen at 38, the output 40 of the photodiode will momentarily .
SA977Ql9 -8.-' ' 1 drop. The known posltion of the X-cursor at this time (Tl) 2 is the X-coordinate oE the light pen.
3 Similarly, a subsequent and slrnilar operation of the ~-4 cursor will provide the Y-coordinate of the light pen.
~ preferred embodiment ~or a transmissive LV is shown 6 in Fig. 6. A projec-tion lamp 42 having visible light 44 7 represented by an arrow with a single line, nea~-IR radiation 8 46 represented by an arrow with a double line, and IR
g radiation 48 represented by an arrow with a wavy line.
The radiation 44, 46, and 48 is collimated by the condenser 11 lens 50. The collimated radiation is direc-ted to hot 12 mirror 52 which transmits the visible light 44 and reflects 13 the IR radiation 46 and the near-IR 48~ Radiation 46 and 48 is directed to a special cold mirror 54 which transmits the IR radiation 48 and reflects the near-IR
16 radiation 46 to a condenser lens 56. The near-IR
17 radiation 46 is reflected off of a folding mirror 58 to à
18 hot mirror 60. The visible light 44 which is passed -through 19 the hot mirror 52 passes through a condenser lens 62 and a light valve which is located in plane 64. The visible light 21 then passes -through hot mirror 60 and con~inues along with 22 the near IR radiation 46 to relay lens 66 which relays an 23 image of light valve in plane 64\into the~ plane of the 24 cursor wires located a-t 68. The light then proceeds through a field lens 70 which images the aperture of the relay lens 26 66 into the aperture of the projection lens 72. The pro-27 jection lens 72 images plane 68 onto a screen (not shown.) 28 Hence, the screen displays an image of the LV whose 29 image was relayed into plane ~8 and also àn image of the cursor wires which are located in plane 68.
~A977019 -9_ .~ ' .
1 The ~referred embodiment describecl above in Eig. 6 2 utillzes the near-IR radiatioII as the spec-tral componen-t 3 which passes through the plane 68 to forr,l an image of the 4 cursor wires on a screen which is subsequently sensed by a light pen sensitive to the near IR radia-tion.
6 It is understood that numerous variations of the embodiments shown in Fig. 6 can be used. For example, the 8 mïrror 60 may also be used for directing on to the LV 64 a neàr--IR laser, such as Nd:YAG for the purpose of writing on the LV. It is also understood that ins-tead of using a portion 11 of the lamp spec-trum for the néar-IR, a se?arate narrow 12 bandwidth source could be used. For example, the special 13 cold mirror 54 could be removed and a GaAs IR diode could be 14 put in its place.
Another embodiment suitable for a reflective LV is shown 16 in Fig. 7. A lamp 80 transmits visible light 82, near IR
17 radiation 84 and IR radiation 86 through a condenser lens 88 18 which collimates the light from the lamp 80. The light 19 passes through the condenser lens 89 and forms an image of the lamp filament on an elliptical mirror 90 on the aperture 21 plate 94. The elliptical mirror 90 reflects visible light 22 but transmits IR and near-IR radiation. The aperture plate 23 94 contains an aperture 91 and a front surface mirror 92 on 24 the opposite side of the aperture plate to elliptical mirror 90 Aperture ~late 94 is suitable for a sub-tractlve LV. Altern-26 atively, aperture plate 94A is for an additive LV and has an 27 elliptical mirror 90A, a front surface mirror 92A on the opposite 28 side of the aperture plate to 90A and an opaque stop 93A. The 29 near IR radiation 84 and the IR radiation 86 which passes -through the el:liptical mirror 90A continues and passes SA977019 -1~-~r ~
' ' ' ' 3~
1 througl1 con~ellser lerls 96 to a special cold mirror.98 which ; 2 -transmits the IR heat 86 bu-t ref:Lects the near IR radiation ; 3 8~. The near IR ra(iiation 84 that :is refl.ec-ted by the mirror 98 passes through the condenser lens 96 and Eorms.
an image of the lamp filamen-t on mirror 92~
6 The visible light 82 is reflected by mirror 90 (90A) 7 and passes -through a -telecen-tric schlieren lens 100 to a re:flective 8 light valve 102. The rei'lective ligh-t valve 82 reElec-ts 9 visible light 82 through the lens 100 to the aperture 91 on : 10 aperture plate 94 (or a.round the opaque s-top 93A on aperture 11 plate 94). The visible ligh-t 82 and the near IR radiation 12 84 passes.through relay lens 103 which along with lens 100 13 forms an image o:E the light valve 102 in plane 104, the l4 location oE -the cursor wires. Field lens 106 images the aperture of relay lens 103 into the aperture of projection 16 lens 108 which images plane 10 onto a screen not shown.
17 It is understood tha-t the invention could be utilized 18 with an image from a CRT or similar photoemissive display 19 element when used in a projection display mode.
. This invention is particularly useful for projection 21 systems employing a reflective liquid crystal light valve.
22 Although some preferred embodiments of this invention 23 have been described, it is understoo'd that numerous variations 24 may be made in accordance with -the principles of this lnvention.
' 25 ; 26 : . 28 29 . ; ' :~ 30 ' .~ - - .
.
~ ,'''' ' . , '
Claims (12)
1. An interactive projection display system having an image of a light valve on a projection screen formed by visible light of specified wavelengths and having a trans-latable crosswire image formed by radiation which includes the visible light used to form the light valve image and an additional spectral component on the projection screen which is distinguishable from the light valve image comprising:
a light pen device sensitive to the additional spectral component used to form the crosswire image wherein said light pen device senses the position of the crosswire image on the screen.
a light pen device sensitive to the additional spectral component used to form the crosswire image wherein said light pen device senses the position of the crosswire image on the screen.
2. A light pen device suitable for use in an interactive projection display system as defined in claim 1 comprising:
filter means adapted to transmit radiation having substantially the same wavelengths as the crosswire image;
and photodiode means adapted to be sensitive to the radia-tion transmitted by said filter means.
filter means adapted to transmit radiation having substantially the same wavelengths as the crosswire image;
and photodiode means adapted to be sensitive to the radia-tion transmitted by said filter means.
3. A light pen device suitable for use in an interactive projection display system as defined in claim 1 comprising:
filter means adapted to transmit radiation having substantially the same wavelengths as the additional spectral component; and photodiode means adapted to be sensitive to the radia-tion transmitted by said filter means.
filter means adapted to transmit radiation having substantially the same wavelengths as the additional spectral component; and photodiode means adapted to be sensitive to the radia-tion transmitted by said filter means.
4. A system as described in Claim 1 or Claim 2 wherein said light pen device is sensitive to radiation having a wavelength between 0.7 um and 1 um.
5. A light pen device as described in Claim 2 or Claim 3 wherein said filter means transmits radiation having a wavelength between 0.7 um and 1 um.
6. An interactive projection display system comprising:
a projection screen;
first means to provide an image of a light valve formed by visible light of specified wavelengths on said screen;
second means to provide a translatable crosswire image on said screen distinguishable from the light valve image wherein said second means provides a translatable crosswire image on said screen with an additional spectral component not present in the visible light used to form the light valve image; and a light pen device sensitive to the crosswire image wherein said light pen device senses the position of the crosswire image on said screen.
a projection screen;
first means to provide an image of a light valve formed by visible light of specified wavelengths on said screen;
second means to provide a translatable crosswire image on said screen distinguishable from the light valve image wherein said second means provides a translatable crosswire image on said screen with an additional spectral component not present in the visible light used to form the light valve image; and a light pen device sensitive to the crosswire image wherein said light pen device senses the position of the crosswire image on said screen.
7. A display system as described in claim 6 wherein said first means provide an image of a transmissive light valve.
8. A display system as described in claim 6 wherein said first means provide an image of a reflective light valve.
9. A display system as described in claim 6 wherein said first means provide an image of a photoemissive display element.
10. A display system as described in claim 6 wherein said second means provides a translatable crosswire image on said screen with radiation having a wavelength between 0.7 um and 1 um.
11. A display system as described in claim 6 wherein said first means and said second means use the same radiation source.
12. A display system as described in claim 6 wherein said first means uses a first radiation source and said second means uses a second radiation source.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84733277A | 1977-10-31 | 1977-10-31 | |
| US847,332 | 1977-10-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1113619A true CA1113619A (en) | 1981-12-01 |
Family
ID=25300362
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA307,632A Expired CA1113619A (en) | 1977-10-31 | 1978-07-18 | Interactive projection display system |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5468117A (en) |
| CA (1) | CA1113619A (en) |
| DE (1) | DE2843191C2 (en) |
| FR (1) | FR2410326A1 (en) |
| GB (1) | GB1578310A (en) |
| IT (1) | IT1159148B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57166637A (en) * | 1981-04-03 | 1982-10-14 | Nec Corp | Light pen for video projector |
| US4938570A (en) * | 1985-04-18 | 1990-07-03 | Sony Corporation | Method and system for data display and input via display screen |
| DE102010037788B4 (en) | 2010-09-27 | 2012-07-19 | Viprotron Gmbh | Method and device for displaying automatically determined fault locations |
| JP6065533B2 (en) * | 2012-11-15 | 2017-01-25 | カシオ計算機株式会社 | Electronic signage apparatus and operation method |
| CN107015428B (en) * | 2017-04-12 | 2020-05-22 | 浙江思珀整合传播有限公司 | Multimedia interactive projection system |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1864164U (en) * | 1962-07-13 | 1962-12-20 | Manfred R Burger | DEVICE FOR MAKING VISIBLE WRITING RESPONDING TO UV RADIATION. |
| JPS5420092B2 (en) * | 1972-07-15 | 1979-07-20 | ||
| JPS5726369B2 (en) * | 1973-09-06 | 1982-06-04 | ||
| JPS528725A (en) * | 1975-07-10 | 1977-01-22 | Toshiba Corp | Information input device |
-
1978
- 1978-05-19 GB GB20853/78A patent/GB1578310A/en not_active Expired
- 1978-07-18 CA CA307,632A patent/CA1113619A/en not_active Expired
- 1978-09-22 JP JP11607578A patent/JPS5468117A/en active Granted
- 1978-09-26 FR FR7828297A patent/FR2410326A1/en active Granted
- 1978-09-29 IT IT28244/78A patent/IT1159148B/en active
- 1978-10-04 DE DE2843191A patent/DE2843191C2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2843191C2 (en) | 1984-03-29 |
| JPS5468117A (en) | 1979-06-01 |
| DE2843191A1 (en) | 1979-05-03 |
| IT7828244A0 (en) | 1978-09-29 |
| FR2410326B1 (en) | 1983-04-15 |
| JPS5631013B2 (en) | 1981-07-18 |
| FR2410326A1 (en) | 1979-06-22 |
| IT1159148B (en) | 1987-02-25 |
| GB1578310A (en) | 1980-11-05 |
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| MKEX | Expiry |