United States Patent [191
`Kasday
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,484,179
`Nov. 20, 1984
`
`[54] TOUCH POSITION SENSITIVE SURFACE
`[75] Inventor: Leonard R. Kasday, Plainsboro, NJ.
`.
`_
`.
`[73] Assignee. g'ilifilgell Laboratories, Murray
`
`l\Edbelilng et a1- -
`3,712,562 1};
`ue er .
`,8
`,82
`l
`4,177,354 “A979 Mathews ‘
`4,180,702 12/ 1979 Sick et a1. .
`4,198.62‘, 4/1980 Misek et all I
`
`[21] APPL No‘ 333,744
`.
`_
`[22] F?ed'
`
`Dec' 23’ 1981
`.
`.
`Related US. Application Data
`
`OTHER PUBLICATIONS
`D. Brini, L. Pell, 0. Rimondi, P. Veronesi, “On Large
`Scintillation Counters”, Supplemento a1 vol. II, Serie X,
`Del Nuovo Cimento, N. 4, 1955, 20 Semestre, pp.
`1062_ 1069.
`
`is .N . 140,715, A .16,1980, b -
`t'
`C '
`63
`(13,123?“ Ion 0 er
`0
`pr
`8 an
`[
`1
`[51] I t Cl 3
`case 9/00
`
`_
`Primary Examiner-David L. Trafton
`Attorney, Agent, or Firm—David H. Tannenbaum
`
`n .
`
`.
`
`.............................................. ..
`
`[52] us. 01. ........................ .. 340/365 P; 178/18;
`_
`250/549; 340/712
`[581 new of Search ------------- -' 340/365 P’ 712’ 81524’
`340/8153 1; 178/18; 250/549
`References Cited
`
`56
`i
`]
`
`U.S. PATENT DOCUMENTS
`2,227,083 12/1940
`3,271,515 9/1966
`3,526,775 9/1970
`3,621,268 11/1971
`3,673,327 6/1972
`3,707,715 12/1972
`3,764,813 10/1973
`
`Handrick ............................ .. 178/18
`Harper .
`Friedrich et a1. ............. .. 340/365 P
`Friedrich et a1. .
`Johnson et al. ............... .. 340/712 X
`Perotto .......................... .. 340/365 P
`Clement et a]. .
`
`ABSTRACT
`[57]
`A touch sensitive device is arranged with substantially
`parallel surfaces which are at least partially transparent
`to light. A ?exible membrane is supported above the top
`surface of the screen and when the overlay is ?exed into
`contact with the screen, light which had passed through
`the screen, is trapped between
`the screen surfaces by
`total internal re?ection. The edges of the screen are
`?tted with light detectors for gathering the trapped
`light. Using this arrangement positional determination
`of one or more screen touches is possible.
`
`30 Claims, 9 Drawing Figures
`
`30
`
`101
`
`Samsung USP 7,973,773
` Exhibit 1009 Page 1
`
`

`
`US. Patent Nov. 20, 1984
`
`Sheet 1 of5
`
`4,484,179
`
`mom
`RASTER comaor. (CT
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`POWER SUPPLY
`
`F I6‘. I
`
`60
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`IO
`
`3o
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`
`OUTPUT
`SIGNAL
`
` Exhibit 1009 Page 2
`
`

`
`U.S. Patent Nov. 20, 1984
`
`Sheet 2 of5
`
`4,484,179
`
` Exhibit 1009 Page 3
`
`

`
`U.S. Patent Nov. 20, 1984
`
`Sheet 3 of5
`
`4,484,179
`
`FIGS
`
` Exhibit 1009 Page 4
`
`

`
`U.S. Patent Nov. 20, 1984
`
`Sheet 4 of 5 '
`
`4,484,179
`
`FIG. 6
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` Exhibit 1009 Page 5
`
`

`
`Patent Nov. 20, 1984
`
`Sheet 5 of5
`
`4,484,179
`
` Exhibit 1009 Page 6
`
`

`
`1
`
`4,484,179
`
`2
`SUMMARY OF THE INVENTION
`Advantage is taken of the fact that the CRT raster is
`a synchronized signal, the position of which is known at
`any point in time. I have overlaid the CRT screen with
`a device having parallel surfaces, such as a glass plate,
`through which light generated by the raster is visible to
`the user. The edges of the device are ?tted with photo
`diodes which respond to the entrapment of light be
`tween the parallel surfaces to provide an output. By
`touching the top surface of the device (i.e., changing the
`medium bounding the surface) at a point, the light from
`the CRT screen surface becomes entrapped within the
`device by total internal re?ection.
`One problem which must be addressed in designing
`such a touch sensitive screen is the matter of re?ectivity
`as it affects output light levels. The problem is manifest
`in situations where the photodiode coupling at the side
`of the screen is incapable of distinguishing between a
`touch and a non-touch in the presence of background
`noise, or build-up of oils on the screen surface. I have
`solved this problem by overlaying the top surface of the
`device with a ?exible membrane separated from the
`device by a small air gap. The membrane has a half tone
`pattern of small white dots on its upper surface so as to
`partially re?ect the light from the CRT. (Other patterns
`such as stripscould also be used). However, as long as
`the air gap remains between the device and the overlay
`membrane, the refraction angle in the glass is such as to
`prevent total internal reflection from occurring be
`tween the surfaces of the device.
`When a user presses the membrane it is de?ected to
`make intimate contact with the top surface of the device
`thereby removing the air gap and allowing the re?ec
`tive rays of light to reenter the device and become
`entrapped therein by total internal re?ection. This
`trapped light then travels to the sides of the device
`where the photodiodes detect the entrapment. By coor
`dinating the time of the changed photodiode output
`with the CRT raster position the exact surface position
`of the touch is determinable.
`to visually verify the
`Another use of this device is
`proper placement of a movable member. In such an
`environment a ?xed light source would be used and the
`member brought into contact with the membrane.
`When the member was positioned properly total inter
`nal re?ection would occur and light would be seen
`emerging from the edge of the device
`
`TOUCH POSITION SENSITIVE SURFACE
`
`This is a continuation of application Ser. No. 140,715
`?led Apr. 16, 1980, now abandoned.
`
`FIELD OF THE INVENTION .
`
`This invention relates to a device for determining the
`position of a surface contact and more particularly to a
`touch sensitive device for use with a synchronized light
`source, such as a cathode ray tube (CRT).
`
`BACKGROUND OF THE INVENTION
`
`25
`
`45
`
`There are many applications where it is desired to
`provide feedback information for information displayed
`on a CRT screen. For example, it has become common
`practice with the use of computers to display on the
`screen a choice for the user to select from. The user is
`typically instructed to operate speci?c keys, on a key
`20
`board or similar device, to select from among a menu of
`possible choices. In response to the user operating the
`selected key the menu is changed and the user is given
`a new choice, again making the choice by operating a
`particular key. Such an arrangement is tedious since a
`user must ?rst lock at the screen and then go to a sepa
`rate keyboard to ?nd the proper key. This is time con
`suming and requires costly separate equipment.
`One possible solution to the problem has been to
`arrange the menu of choices along a side of the viewing
`screen and to arrange next to the screen a series of
`buttons. As the labels on the screen change the buttons
`become dynamically relabeled. While this solves some
`of the problems it does not allow for complete ?exibility
`of the visual display and still requires an arti?cial ar
`rangement of the display.
`Several attempts have been made to solve the prob
`lem, one such being the use of a light pen which is held
`over the point on the CRT screen corresponding to the
`desired response. Light from the CRT raster then enters
`the pen and the position of the raster is determined by
`coordinating the signal output from the pen with the
`position on the raster at the time of the signal. This
`arrangement, while performing properly, has the disad
`vantage of requiring the user to hold a pen and to prop
`erly direct the pen to the proper place on the screen.
`Other touch sensitive screens used crossed wires,
`crossed beams of infra red light, re?ection of acoustic
`surface waves, current division in resistive sheets, force
`balancing, or mechanical buttons on which a display
`image was superimposed by a half silvered mirror.
`When used with a CRT display, the foregoing methods
`require careful calibration to establish correspondence
`between points on the touch screen and poins on the
`display. The need for special transducers or many elec
`trical connections increase complexity and cost. Also,
`most of the methods only allow activation of one point
`at a time.
`Thus, it is desired to solve these problems in a manner
`which allows the visual display to be touched directly
`at any location on a dynamically changing basis with
`the position of the touch being easily determinable.
`These problems must also be solved in a manner which
`allows for ?ngers of varying degrees of dampness and
`for the use of screens in ambient light conditions which
`vary considerably from place to place.
`
`BRIEF DESCRIPTION OF THE DRAWING
`These attributes of my invention as well as others will
`be more fully appreciated from a review of the drawing
`in which:
`FIG. 1 shows a pictorial view of a CRT screen over
`laid by my device;
`FIG. 2 is a schematic representation showing the
`device with the ?exible overlay membrane, the overlay
`being in the relaxed position;
`FIG. 3 shows my device with the membrane being
`de?ected into contact with the top parallel surface;
`FIGS. 4 and 5 show the principles on which my
`invention is based;
`FIG. 6 shows a block diagram of an operational sys
`tem;
`,
`FIG. 7 shows another block diagram of a system
`similar to “light pen” system;
`FIGS. 8 and 9 show a ?exible structure having signal
`detectors communicating therewith.
`
`60
`
`65
`
` Exhibit 1009 Page 7
`
`

`
`5
`
`20
`
`40
`
`3
`DETAILED DESCRIPTION
`As shown in FIG. 1, CRT screen 20 is arranged in the
`well known manner such that electrons from the elec
`tron gun (not shown) impinge upon the phosphorescent
`screen of the CRT in a sequential pattern, line by line,
`from top to bottom. As the electrons hit the phospho
`rescent surface the surface glows. Phosphorescent im
`ages can thus be formed on the screen under control of
`the electron beam. This phenomenon, of course, is now
`well known and forms the basis of television and other
`CRT systems.
`By properly programming the system it is possible to
`have any type of image displayed at any position on the
`screen for any length of time. Thus, it is possible to
`create images representative of numbers, sets of num
`bers, letters, or signals in any position on the face of
`CRT 20, as shown. Using my device, which is a contin
`uation of elements 10 and 11 of system 60, it is possible
`to allow a user to touch any position on the device and
`to determine electronically the position of the touch. In
`order to accomplish this, I have overlaid the CRT
`screen with device 10 having parallel surfaces through
`which light from the phosphorescent screen may pass. I
`have overlaid device 10 with ?exible membrane 30
`which advantageously may be transparent silicone rub
`ber.
`Membrane 11 is separated from top surface of device
`10 by any one of several means as, for example, stretch
`ing between supports or resting against ridges, protru
`sions, or ?exible tabs dispersed about the surface. The
`?exible membrane is constructed with a half tone white
`dot pattern on its outer surface (other patterns such as
`strips could also be used). This construction allows light
`from the CRT screen to pass through the membrane to
`be viewed by a user as well as being re?ected back
`towards the CRT screen. When the CRT screen
`projects an image calling for user response, a finger or
`other device is placed against the outer surface of the
`membrane at the position selected (the number 6 in
`FIG. 1). When this occurs, as will be explained from
`that which will follow, light becomes trapped within
`device 10. This trapped light travels to the edge of the
`device and is detected by photodiodes 101 thereby pro
`viding an output signal useable for determining the
`position of the touch. The actual determination of the
`touch position is accomplished by coordinating the
`position of the CRT raster beam with the time of the
`output signal. This coordination and determination is
`the subject of concurrently ?led copending US. patent
`application of S. W. Bell, R. L. Breeden
`and M. J. Sa
`bin, Ser. No. 140,715 which application is hereby incor
`porated by reference herein as though fully reproduced
`in this application.
`The coordination and determination can also be done
`by the system shown in FIG. 7, which is similar to that
`used for light pens. This system can detect more than
`one touch at a time. This results from the fact that the
`computer can use the threshold detector outputs to
`record all times that an output signal is received from
`the photodetectors and ampli?ers, and then coordinat
`ing these times with raster beam positions. Further
`more, since increasing the touch force would in general
`increase the area of contact between the sheets, and
`hence increase the duration and number of output sig
`nals associated with each
`touch, the system could dis
`criminate different levels of force.
`
`4,484,179
`4
`Turning to FIG. 2, CRT raster beam 13 is shown
`impinging on the front surface of CRT 20 with light
`rays 21 from the phosphorescent surface passing
`through the parallel surfaces of device 10 and into mem
`brane 11. Some light rays (not shown) are transmitted
`outward toward the user and some are re?ected back
`toward the CRT screen. Because of the air gap 30 be
`tween the lower surface of ?exible membrane 11 and
`outer surface 14 of device 10 the re?ected light rays (as
`will be discussed) have an angle of refraction less than
`the critical angle needed for total internal re?ection and
`thus pass through device 10. These light rays, as the
`approach the edge of device 10, can never assume an
`angle suf?cient to become trapped between surfaces 14
`and 15 and thus whatever light approaches the edge of
`the device, passes into a light absorbing surface such as
`surface 102 which may be black plastic matte. Very
`little additional light impinges upon photodiode 101 and
`thus the output signal re?ects internally scattered light.
`In FIG. 3, a ?nger is shown applying pressure at a
`point on the top surface of membrane 11 thereby ?exing
`the membrane into contact with surface 14 of device 10.
`Air is thus removed between membrane 11 and top
`surface 14 of screen 10 at a point directly under the
`point of pressure contact. Membrane 11 has coated
`thereon a surface 12 which is made up, in one embodi
`ment, of halftone white dots to have increased re?ec
`tance and to scatter the light rays.
`With the membrane depressed light generated on the
`surface of CRT 20 near the depression passes through
`device 10 and into membrane 11 and is then re?ected
`back into device 10. These re?ected light rays, since
`they do not now pass through air, do not refract as they
`did in FIG. 2 (as will be discussed) and thus some of
`these rays become trapped between surfaces 14 and 15
`of device 10 by total internal re?ection.
`This trapped light then travels, as shown, within
`device 10 and impinges upon photodiode 101. Note that
`light absorbers 102 are ineffective to absorb this light
`since the light rays do not pass through surfaces 14 and
`15. Thus, the light rays which impinge upon photodiode
`101 cause an output signal which is different from the
`output signal generated when light does not impinge
`upon the photodiode.
`It is important to note that photodiode 101 may be
`any type of device for converting optical or other sig
`nals to electrical energy and may be a single device or
`may comprise a number of individual devices. In some
`applications a device at one surface would be suf?cient
`while in other applications it would be advantageous to
`surround device 10 on all sides with such a transducer
`which, of course, may have a single output or multiple
`outputs.
`To make the device more useful, the sides of the
`white dots facing away from the CRT should be made
`matte black. This increases the contrast of the CRT
`image as viewed by the user, which would otherwise be
`degraded by re?ection of ambient light from the dots.
`The darkening may be done by a variety of means; for
`example oxidizing the exposed surfaces, or by photo
`etching the dots from a combined layer of white and
`dark material. Such contrast enhancement by overlay
`ing matte black dots, would be useful for any CRT,
`even without the touch screen described here.
`
`55
`
`65
`
`Total Internal Re?ection Criteria
`Refraction at a single surface between media of re
`fraction index N1 and N2 is shown in FIG. 4. Light ray
`
` Exhibit 1009 Page 8
`
`

`
`N1 sin 01=N1 sin 02.
`
`(1)
`
`Light ray C approaches the boundary angle 06 which is
`the critical angle for total internal re?ection. This criti
`cal angle, when N2: 1, which is the case for air, is
`shown by the formula
`
`10
`
`sin 9c=N2/N1=1/N1 when N2=1 (air).
`
`(2)
`
`Total internal re?ection takes place when 0 is larger
`than the critical angle such that 0D is greater than 0c.
`Since sin of 0 is less than 1 it follows that N2 must be less
`than N1 for total internal re?ection to take place.
`Turning now to FIG. 5, the conditions for total inter
`nal re?ection (TIF) will be reviewed with respect to a
`device of refractive index N with air (refractive in
`dex: l) at the surfaces of the device. When light ray A
`enters device 10 from air total internal refraction cannot
`take place because the index of refraction at the lower
`surface bends the light ray to an angle smaller than the
`critical angle necessary for total internal refraction
`which is l/N. This follows from use of geometry'and
`Snell’s law since
`
`sin 02=sin 01=sin Oo/N
`
`(3)
`
`30
`
`and sin 0 is less than 1 for all 0.
`In the case of light ray B (FIG. 5) the air space is
`eliminated when the light ray is assumed to enter from
`a medium with an index of refraction NQ>1 which
`occurs when another body is in contact with the bottom
`surface of device 10. Total internal reflection can now
`take place (where air borders the device) because the
`light ray is no longer bent to an angle smaller than the
`critical angle at the lower surface. This follows from the
`fact that
`
`which is greater than the critical angle l/N when
`
`N0 sin 90> l.
`
`45
`
`(5)
`
`When the air space is eliminated on the top surface of
`device 10 as shown by light ray C hitting diffusely
`re?ecting medium 51 light enters the device from dif
`fuse re?ection at top surface 14. In this case, there is no
`refraction to bend the light ray below the critical angle,
`so total internal re?ection can occur.
`
`50
`
`4,484,179
`6
`5
`alone, with photodiodes 101 coupled to its edge. If this
`A is perpendicular to the boundary and does not un
`membrane is positioned near the CRT face, but sepa
`dergo refraction. Light ray B enters the boundary with
`rated by an air gap 80 (FIG. 8), light 13 from the CRT
`an angle 61 and is refracted according to Snell’s law
`will pass through the sheet without reaching the diodes.
`which states
`'
`But if the membrane is ?exed into contact with the CRT
`face at a point, as shown in FIG. 9, some light rays from
`the CRT will become entrapped, impinge upon the
`photodiode 101, and cause an output signal which can
`be used as before for determining position. To improve
`this device, a second membrane 81 having a smaller
`refractive index and partially light absorbent can be
`overlaid on the ?rst membrane. Light will still be en
`trapped in the ?rst membrane but the effect of oil and
`other contamination on the outer surface of the device
`will be reduced.
`Also it is understood that the signals may be light or
`may be electronic so long as they obey the physical
`phenomenon described. It, of course, is to be under
`stood that those skilled in the art may ?nd many appli
`cations and modi?cations using my invention and it may
`be built as a separate device for mating with an existing
`CRT or it may be manufactured as a part of the implo
`sion screen itself. Also, the trapped light may-be re
`moved from the device by any light utilization device,
`such as, for example, ?ber optics or light pipes.
`Using my invention in graphics and taking advantage
`of the fact that multiple positions can be detected, a user
`could rotate a shape by touching two points and rotat
`ing them around each other. A user could position a line
`by simultaneously positioning its endpoints; or could
`specify a quadratic curve by indicating three points
`along its length. Areas could be colored or shaded by
`touching them while pads indicating these attributes
`were simultaneously touched.
`In text processing, a screen with relabelable keys
`could provide a shift button that could be pressed simul
`taneously with other keys. A text editor could combine
`cursor control and touch sensitive buttons on the same
`screen; and the buttons could be touched while the
`- cursor was moved (to change the text font for example).
`My screen can also be made to discriminate different
`levels of force. In graphics, this force discrimination
`could indicate a degree of shading, or could be trans
`lated into linear or rotational velocity.
`Force discrimination could also be used to eliminate
`the effect of parallax; as cursor position could be indi
`cated on the screen as the user moved his or her ?nger
`across the display, and the user could simply press
`harder when the desired position was obtained. It'
`would also be advantageous to make the ?exible over
`lay translucent, and to focus an image upon it by means
`of projection television from the rear. This would given
`a large area screen and the focusing would lead to the
`?nest spatial resolution.
`I claim:
`1. A touch position sensitive device for use in con
`junction with a signal source, said device comprising
`spaced apart surfaces arranged such that signals are
`introduced by total internal re?ection between said
`surfaces as a result of a change in medium bounding
`at least one of said surfaces, and
`'
`a ?exible overlay adjacent said one surface, said over
`lay adapted to be de?ected into contact with said
`one surface in response to a depression of said over
`lay so as to cause said medium change thereby
`providing a distinctive signal level change between
`the surfaces of said device when said signals are
`introduced between said surfaces.
`
`Conclusion
`While the focus of the disclosure is on a CRT type
`light signal my invention may also ?nd use in situations
`where it is desired to position a part in a particular
`location. In such an arrangement a ?xed light source
`may be used at the desired location and the part moved
`mechanically or otherwise to make contact with the
`?exible membrane. When the contact is at the location
`where the light is focused total internal re?ection will
`occur. This total internal re?ection will become visible
`to a person observing the device. Thus my device may
`65
`be useful for determining a surface condition of a screen
`or other device. The device can also be constructed, as
`shown in FIGS. 8 and 9 using the ?exible membrane
`
`55
`
`60
`
` Exhibit 1009 Page 9
`
`

`
`.10
`
`45
`
`4,484,179
`7
`2. The invention set forth in claim 1 wherein a portion
`of said signals pass through said surfaces as well as
`through said overlay.
`3. The invention set forth in claim 2 wherein said
`surfaces are substantially parallel to each other.
`4. The invention set forth in claim 1 wherein said
`distinctive signal is provided by signal utilization means
`communicating with an edge of said device.
`"
`5. The invention set forth in claim 4 wherein said
`signal source
`is a light source and wherein said signals
`which‘ are introduced into said device are light signals
`from said light source.
`6. The invention set forth in claim 4 wherein said
`utilization means includes at least one light detecting
`diode.
`7. The invention set forth in claim 4 wherein said
`utilization means includes optic ?ber means.
`8. The invention set forth in claim 1 wherein said
`?exible overlay has thereon a pattern of re?ective mate
`rial and wherein said overlay is at least partially trans
`parent to said signal.
`‘
`9. A position sensitive device for use in conjunction
`with a source of light, said device comprising _
`substantially parallel surfaces arranged such that light
`from said light source impinging upon one of said
`surfaces is subject to a changeable light ray angle
`within said surfaces due to a change in the medium
`bounding said one surface, and
`'
`. a membrane overlayed on one of said surfaces, said
`overlay adapted for changing said light ray angle.
`10. The invention set forth in claim 9 further compris
`mg
`light utilization means arranged to provide a distinc
`tive output only when said impinging light is sub
`jected to said changed angle so as to become en
`trapped within said device by total internal re?ec
`. tion between said surfaces of said device.
`11. The invention set forth in claim 10 wherein a
`portion of said impinging light passes through said par
`allelsurfaces and through said membrane.
`12. The invention set forth in claim 11 wherein said
`utilization means includes at least one light detecting
`diode.
`13. The invention set forth in claim 11 wherein said
`utilization means includes optic ?ber means.
`~
`-
`14. The invention set forth in claim 9 wherein said
`?exible overlay has thereon a pattern of re?ective mate
`rial and wherein said overlay is at least partially trans
`parent to said synchronized signal.
`15. A touch position sensitive device adapted ‘for
`mating with the screen of a CRT operable for generat
`ing light patterns on the surface thereof, said light pat
`terns being coordinately positioned under control of
`repetitive vertical and horizontal inputs, said device
`comprising
`a rigid sheet of transparent material having inner and
`outer surfaces substantially parallel to each other
`through which light from a mated CRT screen
`passes, said inner surface shaped to mate with said
`CRT, said outer surface being open to air,
`a ?exible membrane overlayed on said outer surface,
`said membrane spaced apart from said outer sur
`face,
`lightaccepting means arranged along at least one
`edge of said device, said accepting means arranged
`for providing outputs indicative of the magnitude
`of the light impinging on said accepting means, and
`
`8 .
`means for positioning said accepting means so that
`light which impinges thereupon comes substan
`tially from within said device between said parallel
`surfaces, and so that when the air bounding said
`outer surface of said rigid sheet is removed at a
`point on said outer surface by contact with said
`membrane said outputs re?ect such contact for a
`period of time corresponding to the time when said
`light is being generated at said position where said
`contact is made.
`16. A device for use in combination with the screen of
`a CRT, said CRT operable for generating light images
`on the screen thereof, said light images occurring as a
`result of a horizontal and vertical scan of an electron
`beam directed against said screen said device including
`a first sheet of material having inner and outer paral
`lel surfaces through which light generated at said
`CRT screen will pass with a refraction angle 91 at
`said inner surface next to said CRT screen and with
`a refraction angle 02 at said outer surface,
`a ?exible membrane overlaying said outer surface,
`photodetecting means arranged along at least one
`> edge of said device and operable for providing an
`output representative of the magnitude of light
`which impinges on said photodetecting means, and
`means for positioning said photodetecting means such
`that said impinging light comes substantially from
`between said surfaces of said ?rst sheet and such
`that when said refraction angle 02 is changed to
`refraction angle 03 by contact between said mem
`brane and said outersurface said photodetector
`means output re?ects said angle change, said re
`fraction angle 03 being such that total internal
`re?ection occurs.
`17. A CRT having a touch position sensitive total
`internally re?ective screen, said screen comprising
`substantially parallel surfaces arranged such that light
`is introduced between said surfaces as a result of a
`change in medium bounding an outer one of said
`surfaces,
`a flexible overlay supportable adjacent to said outer
`surface, said overlay adapted to be de?ected into
`contact with said outer surface in response to a
`depression of said overlay at position, said contact
`causing total internal re?ection to occur within
`said parallel surfaces,
`light detecting means arranged to provide a distinc
`tive output when said light
`is introduced between
`said surfaces so as to become entrapped within said
`screen by total internal re?ection of said surfaces of
`said screen.
`18. The invention set forth in claim 17 further com
`prising
`means for coordinating the position of said light
`across said screen with said distinctive output to
`determine said position on said surface correspond
`ing to said depression.
`19. The invention set forth in claim 17 wherein said
`?exible ovelay has displaced thereon a pattern of re?ec
`60
`' tive material and wherein said overlay is at least par
`tially transparent to said synchronized signal.
`20. The invention set forth in claim19 wherein said
`re?ective material consists of periodically spaced apart
`half-tone‘white dots.
`21. The invention set forth in claim 20 wherein the
`sides of said white dots facing away from said CRT are
`made dark in color.
`
`55
`
`65
`
` Exhibit 1009 Page 10
`
`

`
`9
`22. A touch sensitive device for use in conjunction
`with a light source, said device comprising
`spaced apart ?exible surfaces arranged such that sig
`nals are introduced between said surfaces so as to
`become entrapped within said surfaces by total
`internal re?ection between said surfaces as a result
`of a change in medium bounding at least one of said
`surfaces, said medium change occurring as a result
`of a ?exed contact between said one surface and
`said light source, and
`signal utilization means communicating with a region
`between said surfaces so as to provide a distinctive
`output when said signals are so introduced between
`said surfaces.
`23. The invention set forth in claim 22 further com
`prising a ?exible overlay adjacent
`to one of said sur
`faces, said overlay having a smaller index of refraction
`than said ?exible surface.
`24. The invention set forth in claim 23 wherein said
`overlay is partially light absorbent.
`25. Deflection detection apparatus for use with a
`signal source, said apparatus comprising
`a structure having spaced apart surfaces such that
`signals from said signal source are introduced by
`total internal re?ection between said surfaces, and
`means adjacent one of said surfaces adapted for de
`?ection into contact with said one surface so as to
`cause said introduction of signals between said
`surfaces by total internal
`re?ection.
`26. The invention set forth in claim 25 wherein said
`de?ection means is a ?exible membrane overlaid on said
`one surface and spaced apart therefrom.
`27. A touch sensitive device for use in conjunction
`with a light source, said device comprising
`spaced apart ?exible surfaces arranged such that sig
`nals are introduced between said surfaces so as to
`become entrapped within said surfaces by total
`internal re?ection between said surfaces as a result
`of a ?exure of at least one
`of said surfaces, and
`
`10
`signal utilization means communicating with a region
`between said surfaces so as to provide a distinctive
`output when said signals are so introduced between
`said surfaces.
`28. A touch position sensitive device adapted for
`mating with the screen of a CRT operable for generat~
`ing light patterns on the surface thereof, said
`light pat
`terns being coordinately positioned under control of
`repetitive vertical and horizontal inputs, said device
`comprising
`a ?exible sheet of transparent material having inner
`and outer surfaces substantially parallel to each
`other through which light from a mated CRT
`screen passes, said inner surface shaped to mate
`with said CRT, and
`light accepting means arranged for providing outputs
`indicative of the magnitude of the light impinging
`on said accepting means, said accepting means
`positioned so that light which impinges thereupon
`comes substantially from within said device be
`tween said parallel surfaces, and so that when said
`sheet of material is ?exed to allow light to become
`entrapped within said material by total internal
`re?ection said outputs re?ect such ?exure for a
`period of time corresp