Patent Grant
9063614
The field of the present invention is light-based touch screens.
Many consumer electronic devices are now being built with touch sensitive surfaces (track pad or touch screen), for use with finger or stylus touch user inputs. These devices range from small screen devices such as mobile phones and car entertainment systems, to mid-size screen devices such as notebook computers, to large screen devices such as check-in stations at airports.
In computing, multi-touch refers to a touch sensing surface's ability to recognize the presence of two or more points of contact with the surface. This plural-point awareness is often used to implement advanced functionality such as pinch to zoom or activating predefined programs (Wikipedia, “multi-touch”). The Windows 8 operating system from Microsoft Corporation requires a touch screen supporting a minimum of 5-point digitizers. WINDOWS® is a registered trademark of Microsoft Corporation.
The present invention relates to light-based touch sensitive surfaces. Light-based touch sensitive surfaces surround the surface borders with light emitters and light detectors to create a light beam grid above the surface. An object touching the surface blocks a corresponding portion of the beams.
Reference is made to
Light-based touch detection systems are unable to accurately recognize many instances of two or more points of contact with the surface. Reference is made to
There is further ambiguity when more than two objects touch the screen simultaneously. Reference is made to
Light-based touch screens have many advantages over other touch sensor technologies such as capacitive and resistive solutions. Inter alia, light-based touch screens enable lower bill-of-materials cost than capacitive solutions, especially for large screens. Light-based touch screens are also superior to capacitive and resistive solutions in that a light-based touch screen does not require an additional physical layer on top of the screen that impairs the screen image. This is an important advantage for devices employing reflective screens where the brightness of the screen image depends on reflected light, rather than a backlight. Reference is made to U.S. Pat. No. 8,674,966 for ASIC CONTROLLER FOR A LIGHT-BASED TOUCH SCREEN, incorporated herein by reference in its entirety, which teaches faster scan rates for light-based touch screens than are available using prior art capacitive screens. It would be advantageous to provide a light-based touch screen that is operative to detect multi-touch gestures and that is compatible with the requirements of the Windows 8 operating system.
One drawback of prior art light-based touch screens is the need to accommodate the numerous light emitters and light detectors along all four edges of the screen. This requirement makes it difficult to insert light-based touch detection into an existing electronic device without significantly changing the layout of the device's internal components. It would be advantageous to reduce the number of components required and to enable placing them in a limited area rather than surrounding the entire screen. Reducing the total number of light emitters and light detectors required has the added benefit of reducing the bill-of-materials (BOM).
Embodiments of the present invention provide unambiguous multi-touch detection based on blocked light beams. Other embodiments of the present invention provide 2D touch detection using a one-dimensional array of light emitters along only one edge of the screen and an opposite array of light detectors along the opposite edge of the screen.
There is thus provided in accordance with an embodiment of the present invention a rectangular arrangement of light emitters and light detectors, where light emitters are arranged along two adjacent edges of the rectangular arrangement and light detectors are arranged along the two remaining edges. Light from each emitter is detected by a plurality of the detectors. Each beam from an emitter to a detector traverses a plurality of screen pixels. A table stored in computer memory lists, for each beam, all of the pixels that lie in the beam's path. For each blocked beam, all of the pixels in the beam's path are marked as blocked; and for each non-blocked beam, all of the pixels in the beam's path are marked as unblocked. This creates a map with three types of pixels: fully blocked, fully unblocked and partially blocked. A partially blocked pixel is traversed by several beams, only some of which are blocked. A fully blocked pixel is traversed by several beams, all of which are blocked. The fully blocked pixels correspond to the touch locations. The system then connects adjacent blocked pixels to construct blobs of contiguous blocked pixels. Each blob, or set of contiguous blocked pixels, is treated as a single touch location.
There is additionally provided in accordance with an embodiment of the present invention a touchscreen featuring a row of light emitters along the bottom edge of the screen and a row of light detectors along the top edge of the screen. Each light emitter projects a very wide beam that is detected by all of the light detectors. The x-coordinate of an object touching the screen corresponds to a blocked beam that runs parallel to the side edges of the screen. The y-coordinate is determined by identifying the intersections between diagonal blocked beams.
There is further provided in accordance with an embodiment of the present invention a lens for placement opposite a diode in an optical touch sensor, including an upper portion including an upper refractive surface located nearer to the diode, and an upper reflector located further from the diode, the upper reflector being curved in two dimensions and cut horizontally by a top horizontal plane of the lens, and a lower portion, coplanar with the diode, including a lower refractive surface located nearer to the diode, and a lower reflector located further from the diode, the lower reflector being curved in the two dimensions and cut horizontally by a bottom horizontal plane of the lens, wherein the upper and the lower reflector are symmetrical and vertically aligned, and wherein non-collimated light reflected by the lower reflector onto the upper reflector is partially collimated in the two dimensions by the lower reflector and further collimated in the two dimensions by the upper reflector.
In cases where the lens' viewing angle of the diode is large, the height of the lens between the top and bottom horizontal planes is less than the height required for a curved reflector, cut vertically by a rear vertical backplane of the lens, to partially collimate and further collimate the non-collimated light.
There is yet further provided in accordance with an embodiment of the present invention a method a method for calculating multiple touch locations on a screen including activating a plurality of emitters and detectors around the perimeter of a screen, wherein each emitter-detector pair corresponds to a light beam crossing the screen, from among a plurality of such light beams, and wherein some of the light beams are blocked by one or more objects touching the screen, providing a look-up table listing, for each light beam from the plurality of light beams, other light beams from the plurality of light beams, that intersect that light beam, and their respective points of intersection, (a) identifying a first blocked light beam, (b) accessing the look-up table to identify a second blocked light beam that intersects the first blocked beam, (c) accessing the look-up table to identify intersection points of other blocked light beams that neighbor the intersection point of the thus-identified first and second blocked beams, (d) repeating operations (b) and (c) until all neighboring intersections points of blocked beams have been identified, and group the thus-identified neighboring intersections as a single touch point, and (e) repeating operations (a)-(d) for remaining blocked light beams that were not yet grouped at operation (d).
There is moreover provided in accordance with an embodiment of the present invention a method for calculating multiple touch locations on a screen including activating a plurality of emitters and detectors around the perimeter of a screen, wherein each emitter-detector pair corresponds to a light beam crossing the screen, from among a plurality of such light beams, and wherein some of the light beams are blocked by one or more objects touching the screen, identifying the screen as an initial touch candidate region, for each candidate region: (a) identifying an unblocked light beam crossing that candidate region, (b) dividing that candidate region into multiple candidate regions, separated by the thus-identified unblocked light beam, and (c) repeating operations (a) and (b) for all unblocked beams, and designating the candidate regions whose sizes are larger than a minimum size, as being unique touch locations.
There is additionally provided in accordance with an embodiment of the present invention a method a method for calculating a touch location on a screen including providing a plurality of emitters and detectors around the perimeter of a screen, wherein each emitter-detector pair corresponds to a wide light beam crossing the screen, from among a plurality of wide light beams, activating a screen scan pairing each emitter with an opposite detector, (a) identifying those wide light beams, from the plurality of wide light beams, that are being blocked by an object touching the screen, (b) identifying an area of intersection between substantially perpendicularly oriented ones of the blocked wide beams identified at operation (a), (c) identifying additional blocked wide beams that cross the area of intersection identified at operation (b), (d) determining a degree of blockage for each additional blocked wide light beam identified at operation (c), (e) identifying two-dimensional shapes formed by the intersection of each additional blocked wide light beam identified at operation (c) with the blocked wide light beams identified at operation (a), and (f) calculating a weighted average of the centers-of-gravity of the thus-identified two-dimensional shapes, wherein each center-of-gravity's weight in the sum corresponds to its respective degree of blockage determined at operation (c).
There is further provided in accordance with an embodiment of the present invention a circular touch sensor including a housing, a surface mounted in the housing, including a circular portion exposed to receive touch input, a plurality of light detectors mounted in the housing along a semicircular contour corresponding to a half of the circular portion, wherein an angular pitch between neighboring detectors is constant, a plurality of light emitters mounted in the housing along an opposite semicircular contour corresponding to the opposite portion of the circular portion, and arranged in groups such that an angular pitch between neighboring emitters within each group is θ, and such that an angular pitch between nearest emitters in different groups is θ+a, where a is positive, and a processor connected to the emitters and to the detectors, for synchronously co-activating emitter-detector pairs, and configured to calculate a two-dimensional location of an object touching the circular portion, based on outputs of the detectors.
There is yet further provided in accordance with an embodiment of the present invention a circular touch sensor including a housing, a surface mounted in the housing including a circular portion exposed to receive touch input, a plurality of light emitters mounted in the housing along a semicircular contour corresponding to half of the circular portion, wherein an angular pitch between neighboring emitters is constant, a plurality of light detectors mounted in the housing along an opposite semicircular contour corresponding to the opposite half of the circular portion, and arranged in groups such that an angular pitch between neighboring detectors within each group is θ, and such that an angular pitch between nearest detectors in different groups is θ+a, where a is positive, and a processor connected to the emitters and to the detectors, for synchronously co-activating emitter-detector pairs, and configured to calculate a two-dimensional location of an object touching the circular portion, based on outputs of the detectors.
The present invention will be more fully understood and appreciated from the following detailed description, taken in conjunction with the drawings in which:
The following table catalogues the numbered elements and lists the figures in which each numbered element appears. Similarly numbered elements represent elements of the same type, but they need not be identical elements.
Aspects of the present invention relate to light-based touch screens and light-based touch surfaces. Throughout this specification, the terms “touch screen” and “touch sensitive surface” include touch sensitive electronic displays and touch surfaces that do not include an electronic display, inter alia, a mouse touchpad as included in many laptop computers and the back cover of a handheld device. They also include airspace enclosed by the rectangular emitter-detector sensor frame provided by the present invention.
According to embodiments of the present invention, a light-based touch sensor includes a plurality of infra-red or near infra-red light-emitting diodes (LEDs) arranged along two adjacent edges of a rectangular touch sensitive surface, as defined above, and a plurality of photodiodes (PDs) arranged along the two remaining adjacent edges. The LEDs project light collimated in height, in order to keep it parallel to the screen surface, but the light is spread out in a wide fan to reach many detectors. When this light is blocked by an inserted object, such as a finger or a stylus, the absence of expected light is detected by the PDs. The LEDs and PDs are controlled for selective activation and de-activation by a controller. Generally, each LED and PD has I/O connectors, and signals are transmitted to specify which LEDs and which PDs are activated. In some embodiments, each LED-PD pair is activated separately. In other embodiments, several PDs are activated concurrently during an LED activation.
Reference is made to
Reference is made to
In some embodiments, each emitter has a respective collimating lens apart from the emitter, and each detector has a respective collimating lens apart from the detector. In some embodiments, these collimating lenses form a solid plastic frame along the borders of the rectangular touch screen. In other embodiments, these collimating lenses are absent to enable a wide, 180° spread angle of light beams from each emitter.
Different emitter-detector beams have different levels of detected intensity at their respective detectors. In an exemplary embodiment, 16 diodes are arranged along the screen length and 9 diodes are arranged along the screen width. TABLES I and II below list the detected intensity of unblocked beams from each emitter at each of detectors PD0-PD15 along the screen length (TABLE I), and at each of the detectors PD16-PD24 along the screen width (TABLE II). Empty cells indicate that no signal is detected for the corresponding emitter-detector beam.
The maximum detection intensity in TABLES I and II is 236. A detection intensity of at least 10 was found, by experiment, to be sufficiently greater than a noise signal, and therefore useful for detecting touches. In some embodiments, a threshold of ½ the expected intensity is used to determine whether a beam is blocked. Thus, if the expected intensity is 236, a detection signal below 118 renders the beam as blocked, whereas if the expected intensity is 49, a detection signal below 25 renders the beam as blocked.
In addition, certain beams were found to continue being detected even when the entire screen was blocked. These beams, situated at corners of the touch screen, do not need to cross the screen area in order to arrive at their respective detectors. TABLE III lists the detection values registered when the entire rectangular touch screen area is covered by a solid opaque object.
TABLE IV lists with an ‘x’ the useful beams in this exemplary embodiment by including beams from TABLES I and II having an unblocked detection value of at least 10, and excluding the beams detected in TABLE III.
Touch Coordinate Method
This section describes in detail the operations to determine a tracked object's location. Reference is made
At step 602 a scan is performed for all usable beams listed in TABLE IV. Each beam is marked as either blocked or unblocked, according to a detection threshold, as described hereinabove. Screenshot 612 illustrates the unblocked beams in a case of five simultaneous touches.
At step 603 each pixel in the 2D cell grid from step 601 receives a binary value (blocked=1/not blocked=0). This binary value is a logical AND between all of the binary values from step 602 of LED-to-PD light beams that pass through the cell, according to the stored list from step 601. Thus, in this method unblocked beams are used to mark cells as untouched. A single, unblocked beam passing through a grid cell is sufficient to mark the cell as untouched. According to an alternative method described below intersections of blocked beams are used to fill the grid from step 601. Screenshot 613 illustrates cells marked as untouched (white) and touched (black).
At step 604 touch areas are formed by connecting neighboring blocked grid cells: for each pixel in step 603 having a value of 1 (blocked), four immediate neighbors are checked, namely, top, bottom, left and right neighbors. Any neighbor having a value of 1 is connected. Screenshot 614 illustrates five touch locations 701-705 identified by joining connected neighbors.
At step 605 the touch coordinates and area of each touch location are calculated. In some embodiments, the area of a touch location is the sum of its pixels and the touch position is the center of gravity of the area. In some embodiments, a valid touch location must have a minimum area, e.g., based on the expected size of a finger. Furthermore, in some embodiments a maximum size for a touch object is also provided. When a touch area exceeds the maximum size it is either discarded or it is assumed to contain multiple objects placed together on the screen. Thus, the touch sensor is operable to distinguish between a single finger performing a gesture and multiple fingers placed together performing the same gesture. Similarly, when the system tracks multiple touch objects, the system is operable to continue tracking them as multiple objects even after they are brought together based on the large size of the touch object, e.g., in a pinch gesture.
Reference is made to
Reference is made to
Returning to
At step 622 blocked beams are analyzed in the following manner. When a first blocked beam is identified, the method checks every intersection point along the blocked beam to see if that point is an intersection of two blocked beams. When such an intersection point is identified, the method recursively checks all immediate neighboring intersection points for additional intersections of two blocked beams until no further intersection points of two blocked beams are found. All neighboring intersection points that are also formed by two blocked beams are assumed to belong to the same touch object and are therefore grouped together. This recursive method finds all of the connected intersections belonging to a single touch object. The method is then repeated beginning with a blocked beam not already used in the previous steps. The resulting network of connected intersection points, where pairs of blocked beams intersect, is illustrated inside circle 651 in
Reference is made to
Step 622 is illustrated by frame 640 in
At step 623 the method recursively checks intersection points neighboring point 639 to create a network or web of neighboring intersections that belong to the same touch object. This is illustrated in
At step 624 the method proceeds to analyze the connected intersection points to extract the first and last blocked intersection point on each beam. This provides an outline of the touch area. Thus, in
If a candidate touch location includes at least one unique blocked beam, i.e., if a blocked beam that does not pass through any other candidate touch locations, then it is confirmed to be an actual touch location. If no unique blocked beam corresponds to a candidate touch location, i.e., if all blocked beams passing through the candidate location pass through at least one other confirmed touch location, then that candidate touch location is discarded. In this way phantom touches, i.e., locations corresponding to intersections of blocked beams that are not generated by an object at the intersection location, but rather by two objects that cast a light-beam shadow on that location, are discarded.
Reference is made to
Reference is made to
In some implementations, the method does not proceed beyond dividing Q based on unblocked narrow beams. The method ends when all unblocked beams have been analyzed. Each remaining polygon in Q is assumed to contain a touch object, but the object's location within the polygon is unknown. Reference is made to
Certain touch patterns will generate more separate polygons in Q than touch points. These extra polygons are known as ghost points. One way of disambiguating or eliminating ghost points is to continue the method with a second step of analyzing blocked beams, as explained with reference to
The center of an assumed touch object is the center of gravity of its polygon Q. Alternatively, the center of an assumed touch object is the center of gravity of the polygon defined by Oi∩Q, which may be smaller than polygon 654. Thus, polygons in Q traversed by a unique blocked beam definitely contain a touch object, whereas polygons in Q not traversed by a unique blocked beam but only by blocked beams that traverse multiple polygons in Q possibly contain a touch object. In some embodiments, these possible touch candidates are reported as possible, not definite, touch locations.
Reference is made to
Reference is made to
In order to detect a touch object, having an assumed minimum diameter d, anywhere on the screen, every location on the screen must be within a distance d of at least one beam. Therefore, any area not within a distance d of at least one beam is identified and removed from Q. Put another way, any area farther than d from all beams is an undetectable area R. Any area common to Q and R, namely, R∩Q, is a blind area. Such areas are defined by the beam layout and by the size of d and should be masked out of Q as it is not possible to determine if an object will be present there.
A variation of the method that excludes portions of area Q based on unblocked beams is now described. The method described above uses narrow beams, such that a beam is either blocked or unblocked, i.e., each beam has a binary state. The variation uses wide beams that can be partially blocked. In the case of wide beams an amount of blockage is used to determine where within the beam the blocking object may be located and excluding the remaining portion of the beam from Q.
Reference is made to
Thus, when an object having a radius d blocks a portion of a wide beam, the portion extending from the side of the beam inward, the outer edge of the object must be somewhere along a curve within the beam. Beam light intensities for all possible touch points of an object with radius d are calculated numerically using the model illustrated by
Reference is made to
In some embodiments of the present invention, the iso-curves are measured on the device. This is particularly suitable for systems that employ complex light guides in which the light intensity distribution across the width of the wide beam is not a simple curve, such as the light guide illustrated in
In some embodiments of the present invention, the iso-curves are measured on the device and added as a multiplier along with a and β0.
Conceptually, each iso-curve is the equivalent of a thin beam in the previous method. That is, in the previous method, an unblocked thin beam means that the object of radius d was at least a distance d away from the beam path. Similarly, when for example 20% of wide beam 325 is blocked, that means that, with reference to the iso-curves in
Reference is made to
Although the illustrated wide beams span an area between opposite sides of screen 802, this method also applies to beams that span an area between adjacent screen edges. Reference is made to
Reference is made to
XP=(WaXa+WbXb)/(Wa+Wb), (3)
where the weights Wa and Wb are normalized signal differences for the two beams.
If the pointer is detected by more than two emitter-receiver pairs, then the above weighted average is generalized to
XP=Σ(WnXn)/(ΣWn), (4)
where the weights Wn are normalized signal differences, and the Xn are weight positions. These calculations are described in U.S. Pat. No. 8,674,966, with reference to FIGS. 137 and 143-150 therein, based on an initial assumed Y axis coordinate of the touch. Thus, both an X-coordinate and a Y-coordinate are determined initially. For the sake of exposition, the beams crossing screen 802 in a vertical direction, e.g., beams 101-201 and 101-202, are referred to as vertical wide beams, and beams crossing screen 802 in a horizontal direction, e.g., beams between emitters and receivers along the left and right sides of screen 802, are referred to as horizontal wide beams.
In order to refine the touch coordinate further and resolve any possibility that this determined location is actually a ghost point, a second set of calculations is performed. The first step in this second process is to assemble a list of all of the vertical wide beams that contributed to the X coordinate calculation, e.g., beams 101-201 and 101-202 in the example of
Thus, numerous pairs of intersecting beams are identified in which the intersection covers the determined location. Each such intersection between two wide beams forms a two-dimensional shape, such as rhombus 906 in
When all of the intersecting beams in the secondary list are at least partially blocked, the touch location is refined by calculating a weighted sum using the center of gravity of each rhomboid intersection area multiplied by a weight corresponding to the degree to which that rhomboid's intersecting horizontal beam is blocked. In some embodiments, the weight corresponds to the degree to which both of that rhomboid's intersecting beams are blocked—i.e., both the vertical beam and the horizontal beam.
This process is repeated for the Y coordinate calculation, using horizontal beams that contribute to the initial Y coordinate calculation. In this case, the secondary list for each horizontal wide beam includes wide beams from any emitter along the top edge of the screen to any receiver along the bottom edge of the screen that covers the initial touch location.
Reference is made to
Step 665 is a loop that iterates over each touch candidate calculated in step 664. Step 666 is a loop over the x and y coordinates of each touch candidate. The body of this inner loop is steps 667-671.
At step 667 the system compiles a list of all beams that cross one of the beams used in step 664 and also traverse the coordinate calculated in step 664. In some embodiments this is done by consulting a look up table. In other embodiments, calculations are used to compile this list.
At step 668 the system checks whether any of these incident beams is completely unblocked. If any of these beams is completely unblocked, the candidate touch location is determined to be a ghost point (step 669) and the system advances to the next touch candidate.
If all of the beams at step 668 are partially blocked, the system refines the touch coordinate by calculating a weighted sum of all of the incident beams crossing this touch location. The rhomboid area of overlap between each of the wide beams used in step 664 and each of the wide beams identified in step 667 is calculated at step 670. Then the center of gravity of this area is calculated, and the center of gravity's coordinate along the desired axis is used in the weighted sum. A respective weight is assigned to each center of gravity according to the degree to which the incidental beam is blocked. The refined touch coordinate is a weighted sum of all the center-of-gravity coordinates along the desired axis, calculated at step 670. This weighted sum is calculated at step 671.
Lenses
In some embodiments of the invention each LED and each PD is coupled with a lens. This section explains several lens structure alternatives that maximize the amount of light utilized for touch detection.
A first lens is acylindrical, with a progressive focal length, in order to keep good focus on the associated LED or PD chip for all angles. Reference is made to
Reference is made to
Reference is made to
Reference is made to
Reference is made to
A second option is a light guide featuring both refractive elements and reflective elements. This light guide enables utilizing light emitted from the LED at more extreme angles than lenses that use only refraction, thereby gathering more of the emitted LED light. This light guide allows for a wider pitch within a limited space in the light direction, i.e., a more extreme ratio between the pitch and the depth/length from the chip to the end of the light guide.
Reference is made to
Thus three portions of the output light field 343 are: central, collimated portion 344, and left and right collimated portions 345 and 341. Two gaps 342 in output light field 343 are shown. These are caused by radii 417 joining refractive surface 420 to refractive surface 422 and to reflective surface 421, respectively. Several methods are provided for covering gaps 342, using either microstructures, air gaps in the light guide, or a combination thereof. The air gap solutions close gaps 342, whereas the microstructure configurations reduce the severity of gaps 342, but do not remove them entirely.
Reference is made to
Another method of covering gaps 342 uses an air-gap in the light guide. Two variations are provided. Reference is made to
Light guides 416, 429 and 440 all collimate light in a first dimension, parallel to the screen surface. A curved mirror is used to collimate the light beams in the dimension incident to the screen surface.
For some methods it is useful that the beam intensity varies linearly along the width of light field 343. Reference is made to
Reference is made to
Reference is made to
In some embodiments, refractive surface 463 is a single-curved (x-dimension) surface. In other embodiments the surface facing the diode is straight. Internally reflective surfaces 461 and 462 further collimate the light in both the x- and y-directions. When diodes 107-109 are emitters, collimated light exits lens 460 through flat exit surface 464. When diodes 107-109 are receivers, collimated light enters lens 460 through flat exit surface 464. By cutting reflective surfaces 461 and 462 horizontally with horizontal planes 483 and 484, instead of vertically, the lens has a lower height, as explained above.
Lens 460 is an extremely fast lens suitable for applications requiring much light, yet is extremely compact. For example, in prior art systems in which a diode is placed underneath the screen, light guides for collimating light in the x-direction, i.e., parallel to the screen surface, employ a curved reflective surface that receives the light traveling downward, perpendicular to the x-direction. In prior art lenses, a double-curved reflector is cut vertically by a rear vertical plane of the light guide. The advantages of lens 460 are evident when it is compared to a prior art light guide illustrated in
Reference is made to
By contrast, the minimum height of lens 460 of
Moreover, because lens 460 has two double-curved reflectors it is more powerful, nearby twice as powerful, as light guide 470. Thus, for wide viewing angles the parabolic depth required in lens 460 is substantially less than the parabolic height required in light guide 470.
Reference is made to
Edge Sweep Detection
Reference is made to
In certain embodiments more than one LED-PD pair is provided in order to detect movement of the object across the upper surface in a direction perpendicular to beam 322. This enables the computer to determine that a sweep gesture across the border is being performed, corresponding to the sweep gesture employed by Windows 8 to open the charms bar or to toggle between different running applications.
Reference is made to assignee's U.S. Pat. No. 8,553,014, and co-pending U.S. patent application Ser. No. 14/016,076, both entitled OPTICAL TOUCH SCREEN USING TOTAL INTERNAL REFLECTION, which are incorporated herein in their entirety by reference, and which describe how to project light beam 322 from emitter 106 into a light guide slab and determine location of an object touching the slab's upper surface based on outputs of an opposite detector 206.
Reduced-Component Flexible Touch Screens
Discussion now turns to embodiments of the invention wherein a touchscreen has light guides along only two edges of the screen. Reference is made to
Reference is made to
Reference is made to
In another embodiment of the present invention, PCB 657 is replaced by two PCB strips. In this regard reference is made to
Reference is made to
These embodiments of touchscreens having light guides along only two edges of the screen enable providing optical touch functionality on a flexible screen. In this regard reference is made to
The determination of a touch location in these embodiments is described with reference to
Reference is made to
Reference is made to
Reference is made to
In these embodiments the resolution of the x-coordinate, namely, the coordinate along the length of light guides 479 and 480, is higher than the resolution of the y-coordinate. Therefore, in some embodiments of the invention the touchscreen driver software distinguishes between situations of a single touch and situations of dual touch, or multi-touch. In particular, in some embodiments, multi-touch gestures such as pinch and spread gestures are determined based only on the x-coordinates of the touches. Whereas when only one object is touching the screen the system determines both the x-coordinate and the y-coordinate of the touch object.
Furthermore, x-coordinate detection extends the entire width of the screen, i.e., to the edges of light guides 479 and 480, whereas y-coordinate detection is limited to an inscribed rectangle within the screen in order to provide the multiple diagonal intersecting beams required in order to determine the y-coordinate.
Circular Touch Panel
Embodiments of the subject invention relate to circular touch panels. Certain circular touch panel embodiments target small touch pads and watches, and are roughly 40 mm in diameter. These embodiments support multi-touch. In certain optical touch screen implementations the channel between an LED and a PD consists of a wide beam of light, but for a round touch surface narrow ray-like beams from LED to PD are used. Thus, these embodiments are relatively small and use tightly spaced components. This enables good light coverage even though the individual light fields are narrow.
Component Placement
Reference is made to
Two different setup geometries are used: namely,
Within this circle, there is a lack of positional accuracy. When blocking one or more rays on one side of the center, there will always be another position diametrically opposite where the same rays can be blocked, thus generating the same signals. Therefore, within this circle it is not possible to determine on which side of the center a touch is located.
(ii) LEDs and PDs Positioned on Separate Semicircles
In an embodiment of the present invention, breaking the radial symmetry associated with alternating components is achieved by splitting the circle in half and placing all of the LEDs on one side and the PDs on the other side, where the LEDs and PDs are evenly distributed.
Light Guide Design
Reference is made to
Reference is made to
In the interior of PCB 661 a plurality of electronic components is provided for the proper function of the touch sensitive surface, inter alia, controller 715, which selectively activates and deactivates the LEDs and PDs.
Reference is made to
Reference is made to
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Reference is made to
Reference is made to
Reference is made to
In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific exemplary embodiments without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.
This application is a continuation of PCT Patent Application No. PCT/US14/40579, entitled OPTICAL TOUCH SCREENS, and filed on Jun. 3, 2014 by inventors Robert Pettersson, Per Rosengren, Erik Rosengren, Stefan Holmgren, Lars Sparf, Richard Berglind, Thomas Eriksson, Karl Erik Patrik Nordström, Gunnar Martin Fröjdh, Xiatao Wang and Remo Behdasht. This application is a continuation-in-part of U.S. patent application Ser. No. 13/052,511, entitled LIGHT-BASED TOUCH SCREEN WITH SHIFT-ALIGNED EMITTER AND RECEIVER LENSES, and filed on Mar. 21, 2011 by inventors Magnus Goertz, Thomas Eriksson, Joseph Shain, Anders Jansson, Niklas Kvist, Robert Pettersson, Lars Sparf and John Karlsson. PCT Patent Application No. PCT/US14/40579 claims priority benefit from: U.S. Provisional Patent Application No. 61/830,671, entitled MULTI-TOUCH OPTICAL TOUCH SCREENS WITHOUT GHOST POINTS, and filed on Jun. 4, 2013 by inventors Erik Rosengren, Robert Pettersson, Lars Sparf and Thomas Eriksson;U.S. Provisional Patent Application No. 61/833,161, entitled CIRCULAR MULTI-TOUCH OPTICAL TOUCH SCREENS, and filed on Jun. 10, 2013 by inventors Richard Berglind, Erik Rosengren, Robert Pettersson, Lars Sparf, Thomas Eriksson, Gunnar Martin Fröjdh and Xiatao Wang;U.S. Provisional Patent Application No. 61/919,759, entitled OPTICAL TOUCH SCREENS WITH TOUCH-SENSITIVE BORDERS, and filed on Dec. 22, 2013 by inventors Remo Behdasht, Erik Rosengren, Robert Pettersson, Lars Sparf, Thomas Eriksson;U.S. Provisional Patent Application No. 61/911,915, entitled CIRCULAR MULTI-TOUCH OPTICAL TOUCH SCREENS, and filed on Dec. 4, 2013 by inventors Richard Berglind, Erik Rosengren, Robert Pettersson, Lars Sparf, Thomas Eriksson, Gunnar Martin Fröjdh and Xiatao Wang;U.S. Provisional Patent Application No. 61/923,775, entitled MULTI-TOUCH OPTICAL TOUCH SCREENS WITHOUT GHOST POINTS, and filed on Jan. 6, 2014 by inventors Per Rosengren, Stefan Holmgren, Erik Rosengren, Robert Pettersson, Lars Sparf and Thomas Eriksson; andU.S. Provisional Patent Application No. 61/950,868, entitled OPTICAL TOUCH SCREENS, and filed on Mar. 11, 2014 by inventors Karl Erik Patrik Nordström, Per Rosengren, Stefan Holmgren, Erik Rosengren, Robert Pettersson, Lars Sparf and Thomas Eriksson. U.S. patent application Ser. No. 13/052,511 claims priority benefit from: U.S. Provisional Patent Application No. 61/379,012, entitled OPTICAL TOUCH SCREEN SYSTEMS USING REFLECTED LIGHT, and filed on Sep. 1, 2010 by inventors Magnus Goertz, Thomas Eriksson, Joseph Shain, Anders Jansson, Niklas Kvist and Robert Pettersson;U.S. Provisional Patent Application No. 61/380,600, entitled OPTICAL TOUCH SCREEN SYSTEMS USING REFLECTED LIGHT, and filed on Sep. 7, 2010 by inventors Magnus Goertz, Thomas Eriksson, Joseph Shain, Anders Jansson, Niklas Kvist and Robert Pettersson; andU.S. Provisional Patent Application No. 61/410,930, entitled OPTICAL TOUCH SCREEN SYSTEMS USING REFLECTED LIGHT, and filed on Nov. 7, 2010 by inventors Magnus Goertz, Thomas Eriksson, Joseph Shain, Anders Jansson, Niklas Kvist, Robert Pettersson and Lars Sparf. U.S. patent application Ser. No. 13/052,511 is a continuation-in-part of: U.S. patent application Ser. No. 12/371,609, now U.S. Pat. No. 8,339,379, entitled LIGHT-BASED TOUCH SCREEN, and filed on Feb. 15, 2009 by inventors Magnus Goertz, Thomas Eriksson and Joseph Shain;U.S. patent application Ser. No. 12/760,567, entitled OPTICAL TOUCH SCREEN SYSTEMS USING REFLECTED LIGHT, and filed on Apr. 15, 2010 by inventors Magnus Goertz, Thomas Eriksson and Joseph Shain;U.S. patent application Ser. No. 12/760,568, entitled OPTICAL TOUCH SCREEN SYSTEMS USING WIDE LIGHT BEAMS, and filed on Apr. 15, 2010 by inventors Magnus Goertz, Thomas Eriksson and Joseph Shain. U.S. patent application Ser. No. 12/760,567 claims priority benefit from U.S. Provisional Patent Application No. 61/169,779, entitled OPTICAL TOUCH SCREEN, and filed on Apr. 16, 2009 by inventors Magnus Goertz, Thomas Eriksson and Joseph Shain. The contents of all of these applications are hereby incorporated by reference in their entireties.
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