WO2008038275A2

WO2008038275A2 - Optical touch panel

Info

Publication number: WO2008038275A2
Application number: PCT/IL2007/001179
Authority: WO
Inventors: Klony Lieberman; Yuval Sharon; Yossi Chay
Original assignee: Lumio Inc.
Priority date: 2006-09-28
Filing date: 2007-09-25
Publication date: 2008-04-03
Also published as: KR20090077771A; JP5415954B2; JP2010505178A; WO2008038275A3

Abstract

An optical touch panel (100) including a support (104), an optical fiber illumination assembly (102) arranged along and above at least part of a periphery of the support (104) to define a detection region (105), the assembly (102) including at least one optical fiber (111) and a light source (106) arranged for directing light along the at least one optical fiber (111), at least one light detector (122), arranged to detect changes in the light received from the optical fiber illumination assembly (102) produced by the presence of an object (120) in the detection region (105) and detection circuitry receiving at least one output from the at least one light detector (122) and providing an output indication of the two dimensional location of object impingement in the detection region (105).

Description

OPTICAL TOUCH PANEL

REFERENCE TO RELATED APPLICATIONS

Reference is made to U.S. Provisional Patent Application Serial No. 60/827,223, filed September 28, 2006 and entitled OPTICAL SENSING SYSTEM₅ the disclosure of which is hereby incorporated by reference and priority of which is hereby claimed pursuant to 37 CFR 1.78(a) (4) and (5)(i).

Reference is made to U.S. Provisional Patent Application Serial No.

60/819,891, filed July 12, 2006 and entitled "LOW PROFILE TRIANGULATION AND

SYSTEMS CALIBRATION METHOD," the disclosure of which is hereby incorporated by reference. Reference is made to U.S. Provisional Patent Application Serial No. 60/832,508, filed July 24, 2006 and entitled "ACCUMULATOR BASED

TRIANGULATION FOR TRACKING MULTIPLE EVENTS," the disclosure of which is hereby incorporated by reference. Reference is made to U.S. Provisional Patent

Application Serial No. 60/889,746, filed February 14, 2007 and entitled

"TRIANGULATION WITH ENHANCED RESOLUTION," the disclosure of which is hereby incorporated by reference.

Reference is made to U.S. Patent Application Serial No. 11/691,508, filed March 27, 2007 and entitled OPTICAL SYSTEM, the disclosure of which is hereby incorporated by reference.

Reference is made to U.S. Patent Application Serial No. 11/691,510, filed March 27, 2007 and entitled OPTICAL TOUCH SCREEN, the disclosure- of which is hereby incorporated by reference and priority of which is hereby claimed pursuant to 37 CFR 1.78(a) (4) and (5)(i).

Reference is made to U.S. Patent Application Serial No. 11/776,563, filed July 12, 2007 and entitled ILLUMINATION FOR OPTICAL TOUCH PANEL, the disclosure of which is hereby incorporated by reference and priority of which is hereby claimed pursuant to 37 CFR 1.78(a) (4) and (5)(i). 9

FIELD OF THE- INVENTION

The present invention relates generally to optical systems which include optical fibers and optical light guides and more particularly to optical touch panels and optical assemblies useful therein.

BACKGROUND OF THE INVENTION

The following U.S. Patent publications are believed to represent the current state of the art: U.S. Patents 7,099,553; 7,034,809; 6,972,401; 6,783,269; 5,257,340; 5,905,583 and 5,295,047 and U.S. Published Patent Application 2005/0248540.

007/001179

SUMMARY OF THE INVENTION

The present invention seeks to provide an improved optical touch screen or touch panel.

There is thus provided in accordance with a preferred embodiment of the present invention an optical touch panel including a support, an optical fiber illumination assembly arranged along and above at least part of a periphery of the support to define a detection region, the assembly including at least one optical fiber having a core and cladding, the at least one optical fiber having a cross section defining a circumference, the at least one optical fiber having at least one light scattering discontinuity at at least one location therealong, the at least one optical fiber having optical power at at least one light transmissive region having a focus located in proximity to the discontinuity and a light source arranged for directing light along the at least one optical fiber, at least one light detector, arranged to detect changes in the light received from the optical fiber illumination assembly produced by the presence of an object in the detection region and detection circuitry receiving at least one output from the at least one light detector and providing an output indication of the two dimensional location of object impingement in the detection region. Preferably, the at least one light scattering discontinuity has an angular extent of less than ten percent of the circumference and the at least one light transmissive region having an angular extent of more than 25% of the circumference.

Preferably, the optical power of the at least one optical fiber at the at least one light transmissive region and the at least one light scattering discontinuity are operative to direct light, received from the light source along the at least one optical fiber and scattered by the at least one light scattering discontinuity, directly from the at least one discontinuity through the cladding, generally in a plane extending in a direction generally away from the at least one discontinuity. Additionally or alternatively, the at least one light transmissive region is located generally opposite the at least one light scattering discontinuity about the circumference of the at least one optical fiber. Preferably, the at least one optical fiber extends along at least most of a periphery of a light curtain area and the at least one. light scattering discontinuity extends along the periphery, directing light generally in a plane, filling the interior of the periphery and thereby defining a light curtain therewithin. Additionally, the optical touch panel may also include at least one light curtain impingement sensor operative to sense impingement of the light curtain and to produce impingement output signals including two-dimensional impingement location information and output signal processing circuitry for providing an output indication of a two-dimensional impingement location.

Preferably, the at least one optical fiber extends along at least most of a periphery of a light curtain area and the at least one light scattering discontinuity includes a plurality of light scattering discontinuities distributed along the periphery, whereby the plurality of light scattering discontinuities direct light generally in a plane, filling the interior of the periphery and thereby together defining a light curtain therewithin.

Preferably, light scattering functionality of the at least one discontinuity varies along the length of the at least one optical fiber to provide compensation for attenuation produced by the optical fiber. Additionally, the optical power of the at least one optical fiber at the at least one light transmissive region and the at least one light scattering discontinuity having varying light scattering functionality being operative to direct light, received from the light source along the at least one optical fiber and scattered by the at least one light scattering discontinuity, directly from the at least one discontinuity through the cladding, generally in a plane extending in a direction generally away from the at least one discontinuity and having generally uniform intensity.

Preferably, the at least one optical fiber has a non-spherical cross section and the at least one discontinuity is located precisely at a focus of the at least one light transmissive region. Additionally, the optical power of the at least one optical fiber having a non-spherical cross section and the at least one light transmissive region and the at least one light scattering discontinuity located precisely at the focus of the at least one light transmissive region being operative to direct light, received from the light source along the at least one optical fiber and scattered by the at least one light scattering discontinuity, directly from the at least one discontinuity through the cladding, generally in a plane of uniform thickness extending in a direction generally away from the at least one discontinuity.

Preferably, the detection circuitry operates at least partially by triangulation. Preferably, the at least one optical fiber extends along three sides of the detection region, the at least one detector includes a pair of detectors located at adjacent corners of the detection region alongside ends of the at least one optical fiber and wherein the detection circuitry operates at least partially by triangulation.

There is also provided in accordance with another preferred embodiment of the present invention an optical touch panel including a support defining a generally planar surface, an optical illumination assembly arranged along and above at least part of a periphery of the support to define a detection region, the assembly including at least one light guide, the at least one light guide having at least one light scatterer, the at least one light guide having optical power at at least one surface having a focus located in proximity to the light scatterer and at least one light source arranged for directing light along the at least one light guide, the optical power of the at least one light guide and the at least one light scatterer being operative to direct light, received from the at least one light source along the at least one light guide and scattered by the at least one light scatterer, generally in a plane parallel to the generally planar surface, at least one light detector, arranged to detect changes in the light received from the optical illumination assembly produced by the presence of an object in the detection region and detection circuitry receiving at least one output from the at least one light detector and providing an output indication of the two dimensional location of object impingement in the detection region. Preferably, the at least one light guide extends along at least most of a periphery of a light curtain area parallel to the generally planer surface and the at least one light scatterer extends along the periphery of the light curtain area, providing a generally uniform distribution of light in the plane, filling the interior of the periphery of the light curtain area and thereby defining a light curtain therewithin. Additionally, the optical touch panel also may include at least one light curtain impingement sensor operative to sense impingement of the light curtain and to produce impingement output signals including two-dimensional impingement location information and output signal processing circuitry for providing an output indication of a two-dimensional impingement location.

Preferably, the at least one light guide includes a single light guide and the at least one light source includes two light sources, a single light source being placed at each end of the single light guide. Additionally or alternatively, the at least one light source is located only at a corner of the periphery of the detection region.

Preferably, light scattering functionality of the at least one light scatterer varies along the length of the at least one light guide to provide compensation for attenuation produced by the light guide.

Preferably the detection circuitry operates at least partially by triangulation.

Preferably, the at least one light guide extends along three sides of the detection region, the at least one detector includes a pair of detectors located at adjacent corners of the detection region alongside ends of the at least one light guide and wherein the detection circuitry operates at least partially by triangulation.

Preferably, the at least one light guide has a non-spherical cross section and the at least one light scatterer is located precisely at a focus of the at least one surface. Additionally, the non-spherical cross section may include a curved forward portion having optical power. Additionally, the non-spherical cross section may include generally parallel intermediate portions. Additionally, the non-spherical cross section may include tapering rearward portions which meet at a relatively narrow rearward strip portion.

Preferably, the optical touch panel also includes an elongate transparent mounting and window defining guide fixed to the support, the elongate transparent mounting and window defining guide having a U-shaped cross section comprising parallel surfaces and wherein the parallel surfaces engage the generally parallel intermediate portions.

Preferably, the at least one light scatterer includes a layer of light scattering paint. Preferably, the optical touch panel also includes an elongate transparent mounting and window defining guide fixed to the support. Additionally, the elongate transparent mounting and window defining guide may be operative to ensure correct alignment of the optical illumination assembly relative to the support. Additionally or alternatively, the elongate transparent mounting and window defining guide has a U- shaped cross section. Additionally or alternatively, the elongate transparent mounting and window defining guide is operative to minimize light loss from the at least one light guide.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

Figs. IA and IB are simplified illustrations of a touch panel constructed and operative in accordance with two alternative preferred embodiments of the present invention;

Figs. 2A, 2B, 2C and 2D are each a simplified, partially sectional, partially pictorial illustration of a portion of an optical fiber assembly useful in the touch panel of Fig. IA;

Figs. 2E, 2F, 2G and 2H are each a simplified, partially sectional, partially pictorial illustration of a portion of an optical assembly useful in the touch panel of Fig. IB; Fig. 3 is a simplified illustration of an optical fiber assembly structure useful in the touch panel of Fig. IA and providing attenuation compensation;

Figs. 4A and 4B are simplified sectional illustrations of the optical fiber assembly structure of Fig. 3, taken along respective lines IVA - IVA and IVB - IVB;

Fig. 5 is a simplified illustration of another optical fiber assembly structure useful in the touch panel of Fig. IA and providing attenuation compensation;

Fig. 6 is a simplified sectional illustration of the optical fiber assembly structure of Fig. 5, taken along lines VI - VI;

Fig. 7 is a simplified illustration of an optical assembly structure useful in the touch panel of Fig. IB and providing attenuation compensation; and Figs. 8A and 8B are simplified sectional illustrations of the optical assembly structure of Fig. 7, taken along respective lines VIIIA - VIIIA and VIIIB - VIIIB. ■ DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to Figs. IA and IB, which illustrate an optical touch panel 100, constructed and operative in accordance with a preferred embodiment of the present invention. As seen in Figs. IA and IB, the touch panel 100 comprises an optical illumination assembly 102 which is preferably arranged along and above all or part of the periphery of a support 104, typically a glass plate. Alternatively, the glass plate may be obviated and the support 104 may be a frame (not shown). Typically, the optical fiber illumination assembly 102 extends along three of four edges of a generally planar detection region 105.

In accordance with a preferred embodiment of the present invention, the . optical illumination assembly 102 receives illumination from light sources 106, such as an LED or a diode laser, and preferably an infrared laser or LED, disposed at each end 108 of assembly 102. Alternatively, a single light source 106 may be employed, disposed at one end 108 of the assembly 102. As seen in Figs. IA and IB, light sources 106 are preferably located at a corner of the periphery of the generally planar detection region 105.

In accordance with a preferred embodiment of the present invention, as shown in Fig. IA, the optical illumination assembly 102 comprises at least one light guide 110, such as an optical fiber 111 having a core 112 and cladding 114, such as an ESKA plastic optical fiber commercially available from Mitsubishi, which has a circular cross section. The cladding 114 preferably has at least one light scatterer 116, such as a light scattering discontinuity at at least one location therealong, preferably opposite at least one light transmissive region 117 of the light guide 110, at which region the light guide 110 has optical power.

In the illustrated embodiment of Fig. IA, light scatterer 116 is preferably defined by forming a scratch extending entirely through the cladding 114 along at least a substantial portion of the entire length of the optical fiber illumination assembly 102. The scratch may, but need not necessarily, penetrate into the core 112. In the embodiment shown in Fig. IB, the optical illumination assembly 102 comprises at least one light guide 110, such as a plastic rod, which preferably has at least one light scatterer 116 at at least one location therealong, preferably opposite at least one light transmissive region 117 of the light guide 110, at which region 117 the light guide 110 has optical power. A surface of light guide 110 at transmissive region 117 preferably has a focus located in proximity to light scatterer 116.

In the illustrated embodiment of Fig. IB, light scatterer 116 is preferably defined by a narrow strip of white paint extending along the plastic rod along at least a substantial portion of the entire length of the optical illumination assembly 102. In accordance with a preferred embodiment of the present invention, the at least one light scatterer 116 is operative to scatter light which is received from the light source 106 and passes along the at least one light guide 110. The optical power of the light guide 110 at the at least one light transmissive region 117 collimates and directs the scattered light in a direction generally away from scatterer 116, as indicated generally by reference numeral 118. It is appreciated that generally every location in generally planar detection region 105 receives light generally from every location along the at least one light transmissive region 117.

In accordance with a preferred embodiment of the present invention, the at least one light guide 110 extends generally continuously along a periphery of a light curtain area defined by the detection region 105 and the at least one light scatterer 116 extends generally continuously along the periphery, directing light generally in a plane, filling the interior of the periphery and thereby defining a light curtain therewithin.

In an alternative embodiment, the at least one light guide 110 extends along a periphery of a light curtain area defined by the detection region 105 and the at ^■ least one light scatterer 116 includes a plurality of separate light scatterers distributed along the periphery, whereby the plurality of light scatterers direct light generally in a plane, filling the interior of the periphery and thereby together defining a light curtain therewithin.

Impingement of an object, such as a stylus or finger 120, upon support 104 preferably is sensed by one or more light detectors 122, preferably disposed along an edge of detection region 105 along which the optical illumination assembly 102 does not extend. The detectors detect changes in the light received from the optical illumination assembly 102 produced by the presence of finger 120 in the detection region 105. Preferably, detectors 122 are located in the same plane as the optical illumination assembly 102. Preferably, two detectors are sufficient to detect finger 120 anywhere in the detection region 105, each detector being located at an adjacent corner of the detection region 105 and having at least 90 degree coverage, as shown.

Preferably, detectors 122 are each linear CMOS sensors, such as an RPLIS-2048 linear image sensor commercially available from Panavision SVI, LLC of One Technology Place, Homer, New York, which are suitable for use in triangulation. The outputs of detectors 122 are supplied to detection circuitry 124, such as that described in assignee's U.S. Published Patent Application 2006/0187198 and U.S. Provisional Applications 60/819,891; 60/832,508 and 60/889,746, the disclosures of which are hereby incorporated by reference, which provides an output indication of the two dimensional location of the finger 120 impingement in the detection region 105. Reference is now made additionally to Figs. 2A₃ 2B, 2C and 2D, which are each a simplified, partially sectional, partially pictorial illustration of a portion of an optical assembly useful in the touch panel of Fig. IA.

Fig. 2A illustrates the use of an optical fiber 200 having a circular cross section, a core 212 and cladding 214, such as an ESKA plastic optical fiber commercially available from Mitsubishi, having a discontinuity 216 in the form of a longitudinal scratch which extends through cladding 214 and penetrates core 212. In this case, the surfaces 220 defined by the scratch scatter light in the core. A curved light transmissive region 222 lying opposite the discontinuity 216 has optical power and acts generally to collimate the scattered light, as shown, in a plane 224 extending in a direction, indicated- by arrows 226, away from the discontinuity 216.

Fig. 2B illustrates the use of an optical fiber 230 having a circular cross section, a core 232 and cladding 234, such as an ESKA plastic optical fiber commercially available from Mitsubishi, having a discontinuity 236 in the form of a longitudinal scratch which extends through cladding 234 which may but need not necessarily penetrate core 232. In this case, a light scattering material 235, such as white paint, fills at least part of the longitudinal scratch and this material 235 as well as the surfaces 240 defined by the scratch scatter light. A curved cross sectional surface 242 lying opposite the discontinuity 236 has optical power and acts generally to collimate the scattered light, as shown, in a plane 244 extending in a direction, indicated by arrows 246, away from the discontinuity 236. It is a particular feature of the present invention that the light scattering discontinuity has an angular extent of less than ten percent, and more preferably less than one percent, of the circumference of the fiber and that the at least one light transmissive region has an angular extent of more than 25% of that circumference. This feature provides a light curtain of generally uniform thickness. Fig. 2C illustrates the use of a non-conventional optical light guide 250 having a aspheric cross section 252, having a discontinuity 256 in the form of a longitudinal scratch located at a focus 258 of the aspheric cross section 252. In this case, the surfaces 260, defined by the scratch, scatter light. A curved light transmissive region 262 lying opposite the discontinuity 256 has optical power and acts to collimate the scattered light, as shown, to a generally parallel beam in a direction, indicated by arrows 265, away from the discontinuity 256. It is appreciated that cladding (not shown) may be provided peripherally of the light guide 250.

Fig. 2D illustrates the use of a non-conventional optical light guide 270 having a aspheric cross section 272, having a discontinuity 276 in the form of a longitudinal scratch located at a focus 278 of the aspheric cross section 272. In this case, a light scattering material 280, such as white paint, fills at least part of the longitudinal scratch and this material 280 as well as the surfaces 282 defined by the scratch scatter light. A curved light transmissive region 284 lying opposite the discontinuity 276 has optical power and acts to collimate the scattered light, as shown, to a generally parallel beam in a direction, indicated by arrows 285, away from the discontinuity 276. It -is ^• appreciated that cladding (not shown) may be provided peripherally of the light guide 270.

It is a particular feature of the present invention that the light scattering discontinuity has an angular extent of less than ten percent, and more preferably less than one percent, of the circumference of the fiber and that the at least one light transmissive region has an angular extent of more than 25% of that circumference. This feature provides a light curtain of generally uniform thickness. Due to the cross-sectional configuration of the optical light guides 250 and 270, wherein the discontinuities 256 and 276 are located precisely at the respective foci of the light transmissive regions 252 and 272, a light curtain of highly uniform thickness may be realized. Reference is now made additionally to Figs. 2E, 2F, 2G and 2H, which are each a simplified, partially sectional, partially pictorial illustration of a portion of an optical assembly useful in the touch panel of Fig. IB.

Fig. 2E illustrates the use of a light guide 300 having an aspheric cross sectional configuration and at least one light scatterer located precisely at a focus of a light transmissive region thereof. The cross section of light guide 300, as shown in Fig. 2E, preferably includes a light transmissive curved forward portion 302 having optical power, generally parallel intermediate portions 304 and 306, and tapering rearward portions 308 and 310 which meet at a relatively narrow rearward strip portion 312. Preferably strip portion 312 is coated with a layer 314 of light scattering white paint along all or most of its extent. It is appreciated that the light guide 300 may be formed by any suitable manufacturing technique, such as extrusion.

Curved forward portion 302 lies generally opposite strip portion 312 and acts generally to collimate the light scattered by layer 314, as shown, in a plane 324 extending in a direction, indicated by arrows 326, away from the layer 314. Fig. 2F illustrates the use of an alternative example of a light guide 330 having an aspheric cross sectional configuration and at least one light scatterer located precisely at a focus of a light transmissive region thereof. The cross section of light guide 330, as shown in Fig. 2F, preferably includes a light transmissive curved forward portion 332 having optical power, generally parallel intermediate portions 334 and 336, and a rear portion 338 having formed thereon a relatively narrow layer 340 of light scattering white paint along all or most of its extent. It is appreciated that the light guide 330 may be formed by any suitable manufacturing technique, such as extrusion.

Curved forward portion 332 lies generally opposite layer 340 and acts generally to collimate the light scattered by layer 340, as shown, in a plane 344 extending in a direction, indicated by arrows 346, away from the layer 340. Fig. 2G illustrates the use of a light guide 350, similar to light guide 300 (Fig.- 2E) and having an aspheric cross sectional configuration and at least one light scatterer located precisely at a focus of a light transmissive region thereof. The cross section of light guide 350, as shown in Fig. 2G, preferably includes a light transmissive curved forward portion 352 having optical power, generally parallel intermediate portions 354 and 356, and tapering rearward portions 358 and 360 which meet at a relatively narrow rearward strip portion 362. Preferably strip portion 362 is coated with a layer 364 of light scattering white paint along all or most of its extent. It is appreciated that the light guide 350 may be formed by any suitable manufacturing technique, such as extrusion. Curved forward portion 352 lies generally opposite strip portion 362 and acts generally to collimate the light scattered by layer 364, as shown, in a plane 374 extending in a direction, indicated by arrows 376, away from the layer 364.

In accordance with a preferred embodiment of the present invention, light guide 350 is retained within an elongate transparent mounting and window defining member 377, preferably having a U-shaped cross section. Member 377 is typically fixed to a support such as support 104 (Fig. 1). The structure of Fig. 2G ensures correct alignment of the light guide 350 relative to support 104 such that the collimated scattered light designated by reference numeral 118 in Fig. 1 is directed generally parallel to support 104. This alignment is enhanced by the engagement of parallel surfaces defined by intermediate portions 354 and 356 with corresponding parallel surfaces 378 and 379 of member 377. Additionally, the structure of Fig. 2G minimizes light loss from light guide 350 which would otherwise occur due to optical coupling due to adhesive bonding or other types of mounting of light guide 350 on support 104. Member 377 is particularly useful in an optical touch panel structure inasmuch as it provides peripheral sealing of the touch panel.

Fig. 2H illustrates the use of an alternative example of a light guide 380 having an aspheric cross sectional configuration and at least one light scatterer located precisely at a focus of a light transmissive region thereof. The cross section of light guide 380, as shown in Fig. 2H, preferably includes a light transmissive curved forward portion 382 having optical power, generally parallel intermediate portions 384 and 386, and a rear portion 388 having formed thereon a relatively narrow layer 390 of light scattering white paint along all or most of its extent. It is appreciated that the light guide 380 may be formed by any suitable manufacturing technique, such as extrusion.

Curved forward portion 382 lies generally opposite layer 390 and acts generally to collimate the light scattered by layer 390, as shown, in a plane 391 extending in a direction, indicated by arrows 392, away from the layer 390.

In accordance with a preferred embodiment of the present invention, light guide 380 is retained within an elongate transparent mounting and window defining member 393, preferably having a U-shaped cross section. Member 393 is typically fixed to a support such as support 104 (Fig. 1). The structure of Fig. 2H ensures correct alignment of the light guide 380 relative to support 104 such that the collimated scattered light designated by reference numeral 118 in Fig. 1 is directed generally parallel to support 104. This alignment is enhanced by the engagement of parallel surfaces defined by intermediate portions 384 and 386 with corresponding parallel surfaces 394 and 395 of member 393. Additionally, the structure of Fig. 2H minimizes light loss from light guide 380 which would otherwise occur due to optical coupling due to adhesive bonding or other types of mounting of light guide 380 on support 104. Member 393 is particularly useful in an optical touch panel structure inasmuch as it provides peripheral sealing of the touch panel.

Due to the cross-sectional configuration of the optical light guides 300, 330, 350 and 380, wherein the light scatterers are located precisely at the respective foci of the light transmissive forward portions having optical power, a light curtain of highly uniform thickness may be realized.

Reference is now made to Figs. 3, 4A and 4B, which are simplified illustrations of an optical fiber assembly structure 400 useful in the apparatus of Fig.- IA and providing attenuation compensation. An optical fiber 410 is associated at one end thereof with a light source 412. One or more discontinuities 416 are formed in the optical fiber 410, as generally described hereinabove. It is seen in Fig. 3 that the discontinuity 416 may have different depth or width at differing locations along the fiber 410. For example, a portion 420, shown in Fig. 4A, of discontinuity 416 at a location relatively far from the light source 412 is seen to be of greater width and depth than a portion 430, shown in Fig. 4B, of discontinuity 416 at a location relatively close to the light source

412.

Alternatively or additionally, as shown in Figs. 5 and 6, a discontinuity

506 may be composed of mutually spaced discrete discontinuity portions 508, whose density is seen to be greater at locations 510 relatively far from a light source 512 than. at locations 514 relatively close to light source 512.

The result of the variation in the discontinuities, such as discontinuities

416 (Fig. 3) and 506, over the length of the fiber is that attenuation of light traveling along the fiber from the light source at an end of the fiber is compensated such that a generally uniform level of illumination is produced along the length of the illuminating region of the optical fiber assembly structure.

Reference is now made to Figs. 7, 8A and 8B, which are simplified illustrations of an optical assembly structure 600 useful in the apparatus of Fig. IB and providing attenuation compensation. A light guide 610 is associated at one end thereof with a light source 612. One or more light scatterers 616 are formed in the light guide

610, as generally described hereinabove. It is seen in Fig. 7 that the light scatterer 616 may have different depth or width at differing locations along the light guide 610. For example, a portion 620, shown in Fig. 8 A, of light scatterer 616 at a location relatively far from the light source 612 is seen to be of greater width and depth than a portion 630, shown in Fig. 8B, of light scatterer 616 at a location relatively close to the light source

612.

The result of the variation in the light scatterers over the length of the light guide 610 is that attenuation of light traveling along the light guide 610 from the light source 612 at an end of the light guide 610 is compensated such that a generally uniform level of illumination is produced along the length of the illuminating region of the optical illumination assembly structure 600.

It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove.

Rather the scope of the present invention includes both combinations and subcombinations of features recited in the claims as well as modifications thereof which would occur to a person of ordinary skill in the art upon reading the foregoing and which are not in the prior art.

Claims

1. An optical touch panel comprising: a support; an optical fiber illumination assembly arranged along and above at least part of a periphery of said support to define a detection region, said assembly including: at least one optical fiber having a core and cladding, said at least one optical fiber having a cross section defining a circumference, said at least one optical fiber having at least one light scattering discontinuity at at least one location therealong, said at least one optical fiber having optical power at at least one light transmissive region having a focus located in proximity to said discontinuity; and a light source arranged for directing light along said at least one optical fiber; at least one light detector, arranged to detect changes in the light received from said optical fiber illumination assembly produced by the presence of an object in said detection region; and detection circuitry receiving at least one output from said at least one light detector and providing an output indication of the two dimensional location of object impingement in said detection region.

2. An optical touch panel according to claim 1 and wherein said at least one light scattering discontinuity has an angular extent of less than ten percent of said circumference and said at least one light transmissive region having an angular extent of more than 25% of said circumference.

3. An optical touch panel according to claim 1 and wherein said optical power of said at least one optical fiber at said at least one light transmissive region and said at least one light scattering discontinuity are operative to direct light, received from said light source along said at least one optical fiber and scattered by said at least one light scattering discontinuity, directly from said at least one discontinuity through said L2007/001179

cladding, generally in a plane extending in a direction generally away from said at least one discontinuity.

4. An optical touch panel according to claim 3 and wherein said at least one light transmissive region is located generally opposite said at least one light scattering discontinuity about said circumference of said at least one optical fiber.

5. An optical touch panel according to claim 1 and wherein said at least one optical fiber extends along at least most of a periphery of a light curtain area and said at least one light scattering discontinuity extends along said periphery, directing light generally in a plane, filling the interior of said periphery and thereby defining a light curtain therewithin.

6. An optical touch panel according to claim 5 and also comprising at least one light curtain impingement sensor operative to sense impingement of said light curtain and to produce impingement output signals including two-dimensional impingement location information and output signal processing circuitry for providing an output indication of a two-dimensional impingement location.

7. An optical touch panel according to claim 1 and wherein said at least one optical fiber extends along at least most of a periphery of a light curtain area and said at least one light scattering discontinuity includes a plurality of light scattering discontinuities distributed along said periphery, whereby said plurality of light scattering discontinuities direct light generally in a plane, filling the interior of said periphery and thereby together defining a light curtain therewithin.

8. An optical touch panel according to claim 1 and wherein light scattering functionality of said at least one discontinuity varies along the length of said at least one optical fiber to provide compensation for attenuation produced by said optical fiber.

9. An optical touch panel according to claim 8 and wherein said optical power of said at least one optical fiber at said at least one light transmissive region and said at least one light scattering discontinuity having varying light scattering functionality being operative to direct light, received from said light source along said at least one 5 optical fiber and scattered by said at least one light scattering discontinuity, directly from said at least one discontinuity through said cladding, generally in a plane extending in a direction generally away from said at least one discontinuity and having generally uniform intensity.

10 10. An optical touch panel according to claim 1 and wherein said at least one optical fiber has a non-spherical cross section and said at least one discontinuity is located precisely at a focus of said at least one light transmissive region.

11. An optical touch panel according to claim 10 and wherein said optical 15 power of said at least one optical fiber having a non-spherical cross section and said at least one light transmissive region and said at least one light scattering discontinuity located precisely at said focus of said at least one light transmissive region being operative to direct light, received from said light source along said at least one optical fiber and scattered by said at least one light scattering discontinuity, directly from said at ■20 least one discontinuity through said cladding, generally in a plane of uniform thickness extending in a direction generally away from said at least one discontinuity.

12. An optical touch panel according to claim 1 and wherein said detection circuitry operates at least partially by triangulation.

25

13. An optical touch panel according to claim 1 and wherein said at least one optical fiber extends along three sides of said detection region, said at least one detector comprises a pair of detectors located at adjacent corners of said detection region alongside ends of said at least one optical fiber and wherein said detection circuitry

30 operates at least partially by triangulation.

14. An optical touch panel comprising:

• ■ • ■ a support defining a generally planar surface; an optical illumination assembly arranged along and above at least part of a periphery of said support to define a detection region, said assembly including: 5 at least one light guide, said at least one light guide having at least one light scatterer, said at least one light guide having optical power at at least one surface having a focus located in proximity to said light scatterer; and at least one light source arranged for directing light along said at least one light guide, said optical power of said at least one light guide and said at least

10 one light scatterer being operative to direct light, received from said at least one light source along said at least one light guide and scattered by said at least one light scatterer, generally in a plane parallel to said generally planar surface; at least one light detector, arranged to detect changes in the light received from said optical illumination assembly produced by the presence of an object in said 15 detection region; and detection circuitry receiving at least one output from said at least one light detector and providing an output indication of the two dimensional location of object impingement in said detection region.

20 15. An optical touch panel according to claim 14 and wherein said at least one light guide extends along at least most of a periphery of a light curtain area parallel to said generally planer surface and said at least one light scatterer extends along said periphery of said light curtain area, providing a generally uniform distribution of light in said plane, filling the interior of said periphery of said light curtain area and thereby

25 defining a light curtain therewithin.

16. An optical touch panel according to claim 15 and also comprising at least one light curtain impingement sensor operative to sense impingement of said light curtain and to produce impingement output signals including two-dimensional impingement 30 location information and output signal processing circuitry for providing an output indication of a two-dimensional impingement location.

17. An optical touch panel according to claim 14 and wherein: said at least one light guide includes a single light guide; and said at least one light source comprises two light sources, a single light source being placed at each end of said single light guide.

18. An optical touch panel according to claim 14 and wherein said at least one light source is located only at a corner of said periphery of said detection region.

19. An optical touch panel according to claim 14 and wherein light scattering functionality of said at least one light scatterer varies along the length of said at least one light guide to provide compensation for attenuation produced by said light guide.

20. An optical touch panel according to claim 14 and wherein said detection circuitry operates at least partially by triangulation.

21. An optical touch panel according to claim 14 and wherein said at least one light guide extends along three sides of said detection region, said at least one detector comprises a pair of detectors located at adjacent corners of said detection region alongside ends of said at least one light guide and wherein said detection circuitry operates at least partially by triangulation.

22. An optical touch panel according to claim 14 and wherein said at least one light guide has a non-spherical cross section and said at least one light scatterer is located - precisely at a focus of said at least one surface. ^■

23. An optical touch panel according to claim 22 and wherein said non- spherical cross section includes a curved forward portion having optical power.

24. An optical touch panel according to claim 23 and wherein said non- spherical cross section includes generally parallel intermediate portions.

25. An optical touch panel according to claim 24 and wherein said non- spherical cross section includes tapering rearward portions which meet at a relatively narrow rearward strip portion.

26. An optical touch panel according to claim 24 and also comprising an elongate transparent mounting and window defining guide fixed to said support, said elongate transparent mounting and window defining guide having a U-shaped cross section comprising parallel surfaces and wherein said parallel surfaces engage said generally parallel intermediate portions.

27. An optical touch panel according to claim 14 and wherein said at least one light scatterer includes a layer of light scattering paint.

28. An optical touch panel according to claim 14 and also comprising an elongate transparent mounting and window defining guide fixed to said support.

29. An optical touch panel according to claim 28 and wherein said elongate transparent mounting and window defining guide is operative to ensure correct alignment of said optical illumination assembly relative to said support.

30. An optical touch panel according to claim 28 and wherein said elongate transparent mounting and window defining guide has a U-shaped cross section.

31. An optical touch panel according to claim 28 and wherein said elongate transparent mounting and window defining guide is operative to minimize light loss from said at least one light guide.