United States Patent
`[19]
`4,484, 179
`Date of Patent:
`[45] Kasday
`Nov. 20, 1984
`
`Patent Number:
`
`[11]
`
`[54] TOUCH POSITION SENSITIVE SURFACE
`
`[75]
`
`Inventor:
`
`Leonard R. Kasday, Plainsboro, N.J.
`
`[73] Assignee: AT&T Bell Laboratories, Murray
`Hill, NJ.
`
`[21] Appl. No.: 333,744
`
`[22] Filed:
`
`Dec. 23, 1981
`
`Related U.S. Application Data
`
`[63]
`
`Continuation of Ser. No. 140,715, Apr. 16, 1980, aban-
`doned.
`
`Int. Cl.3 .............................................. .. G08C 9/00
`[51]
`[52] U.S. Cl. ................................ .. 340/365 P; 178/18;
`250/549; 340/712
`[58] Field of Search ............. .. 340/365 P, 712. 815.24,
`340/815.31; 178/18; 250/549
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`2,227,083 12/1940 Handrick ............................ .. 178/18
`3,271,515
`9/1966 Harper .
`............... 340/365 P
`3,526,775
`9/1970 Friedrich et al.
`.
`3,621,268 11/1971 Friedrich et al.
`............... .. 340/712 X
`3,673,327
`6/1972 Johnson et al.
`3,707,715 12/1972 Perotto .......................... .. 340/365 P
`3,764,813 10/1973 Clement et al.
`
`3,775,560 11/1973
`Ebeling et al.
`Mueller .
`3,846,826 11/1974
`Mathews .
`4,177,354 12/1979
`.
`4,180,702 12/1979 Sick et a1.
`4,198,623
`4/1980 Misek etal..
`
`.
`
`OTHER PUBLICATIONS
`
`D. Brini, L. Pell, 0. Rimondi, P. Veronesi, “On Large
`Scintillation Counters”, Supplemento al vol. II, Serie X,
`Del Nuovo Cimento, N. 4, 1955, 20 Semestre, pp.
`1062-1069.
`
`Primary Examiner-—David L. Trafton
`Attorney, Agent, or Firm—David H. Tannenbaum
`
`[57]
`
`ABSTRACT
`
`A touch sensitive device is arranged with substantially
`parallel surfaces which are at least partially transparent
`to light. A flexible membrane is supported above the top
`surface of the screen and when the overlay is flexed into
`contact -with the screen, light which had passed through
`the screen, is trapped between the screen surfaces by
`total internal reflection. The edges of the screen are
`fitted 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
`
`.
`
`OUTPUT
`SIGNAL
`
`
`    
`


`
`Samsung USP 8,013,843
`Exhibit 1007 Page 1
`
`

`

`U.S. Patent
`
`Nov. 20, 1984
`
`Sheet 1 of5
`
`4,484,179
`
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`RASTER CONTROL ccr
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`Exhibit 1007 Page 2
`
`

`

`U.S. Patent
`
`Nov. 20, 1984
`
`Sheet 2 of5
`
`4,484,179
`
`-./0102345563789:3;
`
`Exhibit 1007 Page 3
`
`

`

`U.S. Patent
`
`Nov. 20, 1984
`
`Sheet 3 of5
`
`4,484,179
`
`FIG. 4
`
`
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`
`Exhibit 1007 Page 4
`
`

`

`U.S. Patent
`
`Nov. 20, 1984
`
`Sheet 4 of5
`
`4,484,179
`
`SELECT A NUMBER
`
`
`
`
`
`
`I23
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`NUMBER SELECTED
`WILL BE snow [3
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`CONTROLLER
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`
`COMPUTER
`
`704
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`KLMNONPQRSSTQUVWXQY
`
`Exhibit 1007 Page 5
`
`

`

`Patent
`
`Nov. 20, 1984
`
`Sheet 5 of5
`
`4,484,179
`
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`Exhibit 1007 Page 6
`
`

`

`I
`
`4,484,179
`
`2
`
`TOUCH POSITION SENSITIVE SURFACE
`
`SUMMARY OF THE INVENTION
`
`This is a continuation of application Ser. No. 140,715
`filed 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
`
`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 specific keys, on a key-
`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 first look at the screen and then go to a sepa-
`rate keyboard to find 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 dynamicallyrrelabeled. While this solves some
`of the problems it does not allow for complete flexibility
`of the visual display and still requires an artificial 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, reflection 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 fingers of varying degrees of dampness and
`for the use of screens in ambient light conditions which
`vary considerably from place to place.
`
`10
`
`I5
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`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 fitted 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 reflection.
`One problem which must be addressed in designing
`such a touch sensitive screen is the matter of reflectivity
`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 flexible 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 reflect the light from the CRT. (Other patterns
`such as strips_could 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 deflected to
`make intimate contact with the top surface of the device
`thereby removing the air gap and allowing the reflec-
`tive rays of light to reenter the device and become
`entrapped therein by total
`internal
`reflection. 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.
`Another use of this device is to visually verify the
`proper placement of a movable member. In such an
`environment a fixed light source would be used and the
`member brought
`into contact with the membrane.
`When the member was positioned properly total inter-
`nal reflection would occur and light would be seen
`emerging from the edge of the device
`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 flexible overlay membrane, the overlay
`being in the relaxed position;
`FIG. 3 shows my device with the membrane being
`deflected 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 flexible structure having signal
`detectors communicating therewith.
`
`ijklmlnopqqrostuvor
`
`Exhibit 1007 Page 7
`
`

`

`3
`
`DETAILED DESCRIPTION
`
`4,484,179
`
`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 flexible 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 flexible tabs dispersed about the surface. The
`flexible 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 reflected 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 filed copending U.S. 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 amplifiers, 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.
`
`l0
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`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 reflected back
`toward the CRT screen. Because of the air gap 30 be-
`tween the lower surface of flexible membrane 11 and
`outer surface 14 of device 10 the reflected light rays (as
`will be discussed) have an angle of refraction less than
`the critical angle needed for total internal reflection and
`thus pass through device 10. These light rays, as the
`approach the edge of device 10, can never assume an
`angle sufficient 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 reflects internally scattered light.
`In FIG. 3, a finger is shown applying pressure at a
`point on the top surface of membrane 11 thereby flexing
`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 reflec-
`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 reflected
`back into device 10. These reflected 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 reflection.
`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 sufficient
`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.
`the sides of the
`To make the device more useful,
`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 reflection 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.
`
`Total Internal Reflection Criteria
`
`Refraction at a single surface between media of re-
`fraction index N1 and N2 is shown in FIG. 4. Light ray
`
`wxyz{z|}~€}‚ƒ„}…
`
`Exhibit 1007 Page 8
`
`

`

`N1 sin 01=Nz sin 92.
`
`(1)
`
`Light ray C approaches the boundary angle 0c which is
`the critical angle for total internal reflection. This criti-
`cal angle, when N2: 1, which is the case for air,
`is
`shown by the formula
`
`sin 9c=N2/N1=1/N; when N2=1 (air).
`
`(2)
`
`Total internal reflection takes place when 0 is larger
`than the critical angle such that 03 is greater than 0c.
`Since sin of 0 is less than 1 it follows that N2 must be less
`than N1 for total internal reflection to take place.
`Turning now to FIG. 5, the conditions for total inter-
`nal reflection (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 geometryvand
`Snell’s law since
`
`10
`
`15
`
`20
`
`25
`
`sin 9;=sin 9; =sin 00/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 No>l 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
`
`sin 9z=sin 01 =(No/N) sin 00
`
`which is greater than the critical angle I/N when
`
`No sin 90> l.
`
`(4)
`
`(5)
`
`When the air space is eliminated on the top surface of
`device 10 as shown by light ray C hitting diffusely
`reflecting medium 51 light enters the device from dif-
`fuse reflection at top surface 14. In this case, there is no
`refraction to bend the light ray below the critical angle,
`so total internal reflection can occur.
`
`Conclusion
`
`While the focus of the disclosure is on a CRT type
`light signal my invention may also find use in situations
`where it is desired to position a part in a particular
`location. In such an arrangement a fixed light source
`may be used at the desired location and the part moved
`mechanically or otherwise to make contact with the
`flexible membrane. When the contact is at the location
`where the light is focused total internal reflection will
`occur. This total internal reflection will become visible
`to a person observing the device. Thus my device may
`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 flexible membrane
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`5
`A is perpendicular to the boundary and does not un-
`dergo refraction. Light ray B enters the boundary with
`an angle 01 and is refracted according to Snell’s law
`which states
`‘
`
`4,484,179
`
`6
`alone, with photodiodes 101 coupled to its edge. If this
`membrane is positioned near the CRT face, but sepa-
`rated by an air gap 80 (FIG. 8), light 13 from the CRT
`will pass through the sheet without reaching the diodes.
`But if the membrane is flexed 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 first membrane. Light will still be en-
`trapped in the first 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 find many appli-
`cations and modifications 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 maybe re-
`moved from the device by any light utilization device,
`such as, for example, fiber 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 finger
`across the display, and the user could simply press
`harder when the desired position was obtained.
`It"
`would also be advantageous to make the flexible 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
`finest 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 reflection between said
`surfaces as a result of a change in medium bounding
`at least one of said surfaces, and
`'
`a flexible overlay adjacent said one surface, said over-
`lay adapted to be deflected 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.
`
`†‡ˆ‰Š‰‹ŒŽŽŒ‘’“Œ”
`
`Exhibit 1007 Page 9
`
`

`

`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 fiber means.
`8. The invention set forth in claim 1 wherein said
`flexible overlay has thereon a pattern of reflective 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 reflec-
`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-
`allel_surfaces 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 fiber means.
`«
`14. The invention set forth in claim 9 wherein said
`flexible overlay has thereon a pattern of reflective 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 flexible membrane overlayed on said outer surface,
`said membrane spaced apart from said outer sur-
`face,
`least one
`lightaccepting means arranged along at
`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 reflect 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 flexible 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 first 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 reflects said angle change, said re-
`fraction angle 03 being such that
`total
`internal
`reflection occurs.
`17. A CRT having a touch position sensitive total
`internally reflective 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 deflected into
`contact with said outer surface in response to a
`depression of said overlay at position, said contact
`causing total internal reflection 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 reflection 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
`flexible ovelay has displaced thereon a pattern of reflec-
`' tive material and wherein said overlay is at least par-
`tially transparent to said synchronized signal.
`20. The invention set forth in claim. 19 wherein said
`reflective material consists of periodically spaced apart
`half-tonewhite 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.
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`10
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`15
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`20
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`25
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`30
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`35
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`45
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`50
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`55
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`60
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`65
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`•–—˜™˜š›œž›Ÿ ¡¢›œ
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`Exhibit 1007 Page 10
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`

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`9
`22. A touch sensitive device for use in conjunction
`with a light source, said device comprising
`spaced apart flexible surfaces arranged such that sig-
`nals are introduced between said surfaces so as to
`become entrapped within said surfaces by total
`internal reflection 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 flexed 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 flexible overlay adjacent to one of said sur-
`faces, said overlay having a smaller index of refraction
`than said flexible 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 reflection between said surfaces, and
`means adjacent one of said surfaces adapted for de-
`flection into contact with said one surface so as to
`cause said introduction of signals between said
`surfaces by total internal reflection.
`26. The invention set forth in claim 25 wherein said
`deflection means is a flexible 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 flexible surfaces arranged such that sig-
`nals are introduced between said surfaces so as to
`become entrapped within said surfaces by total
`internal reflection between said surfaces as a result
`of a flexure of at least one of said surfaces, and
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
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`35
`
`40
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`45
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`50
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`55
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`60
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`65
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`4,484,179
`
`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 flexible 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 flexed to allow light to become
`entrapped within said material by total
`internal
`reflection said outputs reflect such tlexure for a
`period of time corresponding to the time when said
`light is being generated at said position where said
`flexure occurs.
`29. Deflection detection apparatus for use with a
`signal source, said apparatus comprising
`a flexible structure having spaced apart surfaces such
`that signals from said signal source are introduced
`by total internal reflection between said