Patent Application
20090135162
The present invention relates generally to touch screen displays, and more particularly, to methods and apparatus for detecting the location, size and shape of multiple objects that interact with a touch screen display.
Touch screens are commonly used as pointing sensors to provide a man-machine interface for computer driven systems. Typically, for an optical touch screen, a number of infrared optical emitters (i.e., transmitters) and detectors (i.e., receivers) are arranged around the periphery of the display screen to create a plurality of intersecting light paths. When a user touches the display screen, the user's finger blocks the optical transmission of certain ones of the perpendicularly arranged transmitter/receiver pairs. Based on the identity of the blocked pairs, the touch screen system can determine the location of the intercept (single point interaction). With such a screen, a particular choice can be selected by a user by touching the area of the screen where that choice is displayed, which can be a menu option or a button. This use of perpendicular light beams, while widely used, is unable to effectively detect the shape and size of an object. Neither can the use of perpendicular light beams detect multiple objects or multiple touch points.
It would therefore be desirable for touch screen applications to be able to determine the shape and size of an object, in addition to being able to detect multiple touch points. These applications would also benefit from the ability to determine the transparency and reflectivity of the one or more objects.
The present invention provides methods and apparatus for detecting the location, size and shape of one or more objects placed on a plane within the touch sensor boundaries of a touch screen display. Methods are also provided for detecting an object's, or multiple objects', reflectivity and transparency.
According to an aspect of the present invention, an apparatus for detecting the location, size and shape of an object, or multiple objects, placed on a plane within the touch sensor boundaries of a touch screen, according to one embodiment, includes a plurality of light transmitters (N) and sensors (M) arranged in an alternating pattern on the periphery of the touch screen.
According to another aspect of the present invention, a method for detecting an object's, or multiple objects', location, size and shape, comprises the acts of: (a) acquiring calibration data for each of (N) light transmitters Li arranged around the periphery of a touch screen display; (b) acquiring non-calibration data for each of the (N) light transmitters Li; (c) computing N minimum area estimates of at least one object positioned in the plane of the touch screen display using the calibration data and the non-calibration data computed at acts (a) and (b); (d) combining the N minimum area estimates to derive a total minimum object area of the at least one object; (e) computing (N) maximum area estimates of the at least one object using the calibration data and the non-calibration data computed at acts (a) and (b); (f) combining the N maximum area estimates to derive a total maximum object area of the at least one object; and (g) combining the total minimum and maximum object areas to derive the boundary area of the at least one object.
According to one embodiment, the light transmitters and receivers can be located in separate parallel planes in close proximity. In such an embodiment, the density of light transmitters and receivers is substantially increased thus providing for increased resolution and precision in defining the location, shape and size of the at least one object.
According to one aspect, specific types of photo-sensors may be employed to provide a capability for detecting the reflectivity or conversely the transmissivity of certain objects thus providing additional information regarding the optical properties of the material constituting the object. For example, based on the detected differences in light transmission, reflection, absorption the touch screen can distinguish between a person's hand, a stylus or a pawn used in an electronic board game.
The foregoing features of the present invention will become more readily apparent and may be understood by referring to the following detailed description of an illustrative embodiment of the present invention, taken in conjunction with the accompanying drawings, where:
Although the following detailed description contains many specifics for the purpose of illustration, one of ordinary skill in the art will appreciate that many variations and alterations to the following description are within the scope of the invention. Accordingly, the following preferred embodiment of the invention is set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.
Although the invention is described and illustrated herein in conjunction with a touch screen (i.e., a display with embedded touch sensing technology), the invention does not require the use of a display screen. Rather, the invention may be used in a standalone configuration without including a display screen.
It should also be appreciated that the use of the word ‘touch screen’ throughout this specification is intended to imply all other such XY implementations, applications, or modes of operation with or without a display screen. It should also be appreciated that the invention is not restricted to using infrared light transmitters only. Any kind of light source, visible or invisible, can be used in combination with appropriate detectors. Using light transmitters that emit visible light can give an extra advantage in some cases since it provides visual feedback on the object placed within the touch screen. The visual feedback in such case is the light from the transmitters terminated by the object itself.
As will be described in detail below, the switching order of the light transmitters may be different in different embodiments depending upon the intended application.
Advantages of the detection method of the invention include, but are not limited to, simultaneous detection of multiple objects including, for example, a hand or hands, a finger or fingers belonging to a single and/or multiple users, thereby making the invention applicable to conventional touch screen applications in addition to the creation of new touch screen applications. The ability to detect hands and/or objects allows users to enter information such as size, shape and distance in a single user action, not achievable in the prior art.
The ability to simultaneously detect multiple objects, hands and/or fingers on the touch screen allows multiple users to simultaneously interact with the touch screen display or allowing single users to simultaneously interact with the touch screen display using two hands.
The remainder of the detailed description is organized in the following manner.
First, a detailed description of a method for detecting the size, shape and location of one or more objects interacting with an infrared optical touch screen display is provided. The description includes an illustrative example of how calibration is performed and the calculation of an object boundary area in a non-calibration mode including the acts of computing minimum and maximum boundary area estimates.
Second, a detailed description of techniques for performing object recognition is provided.
Third, a detailed description of different switching schemes is provided.
Fourth, a detailed description of an energy saving or idle mode is provided.
Fifth, a detailed description of identifying objects based on the objects optical properties is provided.
Sixth, a detailed description of various screen shapes and configurations is provided.
Seventh, a detailed description of how the difference in object location on the touch screen can impact the object location, shape and size detection precision is provided.
Eight, a detailed description of the different angular positions that may be selected for the light transmitters is provided.
By way of example, a method for detecting the position, shape and size of objects is now described, according to the infrared optical touch screen display apparatus illustrated in
The method to be described is generally comprised of two stages, a calibration stage and an operational stage.
Calibration Stage
Calibration is performed to collect calibration data. Calibration data is comprised of sensor identification information corresponding to those sensors which detect a light beam transmitted from each of the respective light transmitters located on the periphery of the touch screen display 10 during a turn-on time of each light transmitter. The turn-on time is defined herein as the time during which light emanates from a respective light transmitter in a switched on state. It should be appreciated that in order to obtain meaningful calibration data, it is required that no objects (e.g., fingers, stylus, etc.) interact with the transmission of the light beams during their respective turn-on times in the calibration mode.
During the calibration stage, as each light transmitter is switched on during its respective turn-on time, the light beam that is cast may be detected by certain of the sensors S0-S11 located on the periphery of the touch screen display 10 and may not be detected by certain other sensors. For each light transmitter, L0-L15, the identification of the sensors S0-S11 that detect the respective light transmitter's light beam is recorded as calibration data.
An illustrative example of calibration data collected for the optical touch screen display 10 of
With reference now to the first record entry of Table I, it is shown that, during the calibration stage, during the turn-on time of illuminating light transmitter L0, sensors S5-S11 are illuminated and sensors S0-S4 are not illuminated.
Calibration is described as follows. At the start of calibration, each of the respective light transmitters L0-L15 located on the periphery of the touch screen display 10 are switched to an off state. Thereafter, each of the light transmitters L0-L15 is switched on and off for a pre-determined turn-on time. For example, light transmitter L0 is switched on first for a pre-determined turn-on time during which calibration data is collected. Light transmitter L0 is turned off. Next, light transmitter L1 is switched on for a pre-determined time and calibration data is collected. Light transmitter L0 is turned off. This process continues in a similar manner for each of the remaining light transmitters in the periphery of the touch screen, e.g., L2-L15, the end of which constitutes the completion of calibration.
As each light transmitter L0-L15 in the calibration sequence is turned-on, a beam of light is transmitted having a characteristic two-dimensional spatial distribution in a plane of the touch screen display 10. It is well known that depending upon the particular transmitter source selected for use, the spatial distribution of the emitted light beam will have a different angular width. Selecting a light transmitter having a light beam of a particular angular width may be determined, at least in part, from the intended application. That is, if it is expected that the objects to be detected in a particular application are particularly large having significant width, then light transmitters having a spatial distribution wider than the object itself are more appropriate for that application.
Referring now to
Referring now to the second illuminated region, IR-2, this region is defined as being bounded in the plane of the touch screen by the outermost sensors (S5 and S11) capable of detecting the light beam from the light transmitter L0. It is noted that illuminated regions IR-1 and IR-3 also fall within the illuminated region of the plane of the touch screen, but are separately labeled because they both fall outside the region of detection of the outermost sensors (S5 and S11) capable of detecting the light beam from light source L0. The outermost sensor detection information, e.g., the sensor range (S5-S11) is recorded as part of the calibration data (see the first row entry of Table I above, “outermost illuminated sensors”). As discussed above, the calibration data may additionally include the identification of those sensors that do not detect the light from the light source L0, which in the instant example, are defined by the sensor range S0-S4 as a corollary to the detection information.
After recording the calibration data for light source L0, it is switched off at the end of its turn-on time and the next light source in the sequence, the light source L1, is switched on for its respective turn-on time.
Referring first to the second spatial region, IR-2, this region is bounded by the outermost sensors that detect the light beam from the light source L1, i.e., outermost sensors S4 and S11. Regions IR-1 and IR-3 fall within the lit area of the plane of the touch screen but fall outside the region of detection of the outermost sensors (S4 and S11) capable of detecting the light beam from L1. This sensor detection information is recorded as part of the calibration data (as shown in the second row entry of Table I above). As discussed above, the calibration data may additionally include the identification of those sensors that do not detect the light transmitted from the light transmitter L1, namely, sensor range S0-S3.
After recording the sensor information from the light transmitters L0 and L1 in the manner described above, the calibration process continues in a similar manner for each of the remaining light transmitters located in the periphery of the touch screen, namely, the light transmitters L2-L15.
As will be described further below, the calibration data is used together with non-calibration data acquired during an operational stage to detect the position, shape and size of one or more objects interacting with the touch screen display 10.
Operational Stage
After calibration is complete, the touch screen display 10 is ready for use to detect the position, shape and size of one or more objects interacting with the touch screen display 10.
In accordance with the present illustrative embodiment, detection of the position, shape and size of one or more objects interacting with the touch screen display 10 is performed continuously over multiple cycles of operation. For example, in the illustrative embodiment, each of the light transmitters L1-L15 illuminates in a pre-determined sequence constituting a single cycle of operation which is repeated over multiple cycles of operation.
Similar to that described above for calibration, a single cycle of operation in the operational stage starts with the light source L0 being turned on for a pre-determined turn-on time. After L0 turns off, light source L1 is turned on for a pre-determined turn-on time. This process continues in a similar manner for each light transmitter and ends with light transmitter L15, the last light transmitter in the sequence.
For purposes of explanation, the light distribution pattern of the light transmitter L0 is considered to be comprised of two regions, a first illuminated region labeled Y1 and a second non-illuminated (shadow) region labeled X1.
The illuminated region Y1 defines an area that is not subjected to the shadow cast by the circular object 16 when illuminated by the light transmitter L0. The non-illuminated (shadow) region X1 identifies an area that is subjected to the shadow cast by the circular object 16 when illuminated by the light transmitter L0. The non-illuminated (shadow) region X1 includes sensors S6 and S7 on the touch screen display 10 which detect an absence of light during the turn-on time of the light source L0. This sensor information is recorded as part of the non-calibration data for the current cycle of operation for the present position of the circular object 16 as shown in
In a single cycle of operation, after the light source L0 is turned off at the end of its respective turn-on time, the next light source in the sequence L1 is turned-on for its pre-determined turn-on time. This is illustrated in
Referring now to
The process described above for light transmitters L0 and L1, in the operational mode, continues in the manner described above for each of the remaining light transmitters L2-L15 in the current cycle of operation.
Table II below illustrates, by way of example, for the present illustrative embodiment, the non-calibration data that is recorded over a single cycle of operation in the presence of the circular object 16 for light sources L0-L2. For ease of explanation, table II only shows non-calibration data for three of the sixteen sensors, for a single cycle of operation.
While only a single cycle of operation is discussed above for the operational mode, it should be understood that the operational mode is comprised of multiple cycles of operation. Multiple cycles are required to detect changes in location, size and shape of objects on the screen from one point in time to the next, but also to detect the addition of new objects or removal of already present objects.
During each cycle of operation in the operational mode, minimum and maximum area estimates are made for the detected objects. The estimates are stored in a data repository for later recall in detecting an object boundary area.
Minimum and maximum area estimates are made for each light transmitter (N) located in the periphery of the touch screen. In the present illustrative embodiment, N=16 minimum area estimates are made and N=16 maximum area estimates are made in each cycle of operation.
Upon completing a single cycle of operation, the minimum and maximum area estimates are retrieved from the data repository and combined in a manner to be described below to determine an object boundary area for each detected object in the plane of the touch screen.
The computation of a minimum and maximum area estimate for the first and second light transmitters L0 and L1 for a single cycle of operation are now described with reference to
Referring now to
Recall that the calibration data for light transmitter L0 was found to be the range of illuminated sensors (S5-S11). This sensor range constitute those sensors capable of detecting a presence of light from the light transmitter L0 during calibration (as shown in the first row of Table I).
Recall that the non-calibration data for light transmitter L0 in the presence of the circular object 16 was found to be the sensor ranges (S0-S4) & (S6-S7) detecting an absence of light (as shown in Table II above and illustrated in
Next, a comparison is made of the calibration data and non-calibration data. Specifically, knowing that sensors S6-S7 detect an absence of light during the non-calibration mode and knowing that sensors S5-S11 are illuminated during calibration, the shadow area cast by the object 16 can be determined. This is illustrated now with reference to
Based on the information summarized in Table III above, a minimum area estimate can be determined as follows. The circular object 16 blocks the light path between the light source L0 and sensors S6 (see line P5) and S7 (see line P6). Therefore, the minimum area estimate of object 16, labeled MIN, during the turn-on time of light source L0 is defined by the triangle shown in
Minimum Area Estimate for L0 of object 16=triangle {L0, S7, S6}
It should be understood that triangle {L0, S7, S6} represents the best minimum area estimate given the uncertainty introduced by the distance between the respective sensors S7 and S8 and the distance between the respective sensors S6 and S5.
Using Table III above, a maximum area estimate of object 16, labeled MAX, for light transmitter L0 may be defined in a similar manner. Using the information from Table III, the maximum area estimate is defined by points {L0, S5, C2, S8}. This area is derived by including the sensors S5 and S8 adjacent to the shadow area detected with the sensors S6-S7. It should be noted here that the area includes corner C2 because the line between S5 and S8 should follow the boundary of the screen.
Maximum Area Estimate for L0 of object 16=Area bounded by {L0, S5, C2, S8}
Due to the uncertainty introduced by the distance between the respective sensors S6 and S5 and the distance between the respective sensors S7 and S8, it is reasonable to assume that the object 16 could be covering the area between lines P1 and P2, corresponding to sensors S5 and S8, respectively.
The minimum and maximum area estimates, once determined, are stored in a data repository for each light transmitter for the current cycle of operation. The process of determining a minimum and maximum area continues in a similar manner for each of the remaining light transmitters L2-L15. Further, the minimum and maximum area results are preferably stored in the data repository as geometrical coordinates, such as, for example, the geometrical coordinates of the min and max area vertexes or coordinates of the lines corresponding to area facets.
After a complete cycle of operation, the stored minimum and maximum area estimates are retrieved from the data repository and combined to determine the object boundary area of object 16, as described below.
The method by which the minimum and maximum area estimate results are combined to determine an object boundary area may be performed in accordance with one embodiment, as follows.
The maximum area estimates for each of the N light transmitters Li (e.g., L0-L15), over one cycle of operation, are combined through a mathematical intersection as shown in equation (1) below, to derive a maximum area result, ATotal
The minimum area estimates for each of the N light transmitters Li (e.g., L0-L15), over one cycle of operation, are similarly combined through a mathematical intersection, as shown in equation (2) below, to derive a minimum area result, ATotal
It is noted that areas that do not have a surface (e.g. empty areas or lines) are excluded from the calculation of ATotal
As it is shown in equation (2), after both, ATotal
To compensate for this problem it is required that the total minimum area is contained within the total maximum area, because it is known that the object can never be outside the total maximum area.
ATotal
Other resources include Croft, H. T.; Falconer, K. J.; and Guy, R. K. Unsolved Problems in Geometry New York: Springer-Verlag, p. 2, 1991 and Krantz, S. G. Handbook of Complex Variables Boston, Mass.: Birkhäuser, p. 3, 1999.
Area ATotal in such a way that
ATotal (3a) and
so that every is a closed set that corresponds to a particular object
Similarly, area ATotal in such a way that
ATotal (3b) and
so that every is a closed set that corresponds to a particular object
The total boundary of a single object j ATotal
A
Total j
=F(,
) (4)
for each ⊂
Where F is the function or method of finding ATotal
Referring now to and maximum,
areas to approximate the actual boundary of an object 16.
To approximate the actual boundary of the object 16, we start by determining the center of gravity 61 of the minimum area, labeled II. The method for determining the center of gravity of an object is described in greater detail in Eric W. Weisstein. “Geometric Centroid.” From MathWorld—A Wolfram Web Resource which can be found on the Internet at http://mathword.wolfram.com/GeometricCentroid.html. Other resources for determining the center of gravity 61 of the minimum area (II) include Kern, W. F. and Bland, J. R. “Center of Gravity.” §39 in Solid Mensuration with Proofs, 2nd ed. New York: Wiley, p. 110, 1948 and McLean, W. G. and Nelson, E. W. “First Moments and Centroids.” Ch. 9 in “Schaum's Outline of Theory and Problems of Engineering Mechanics Statics and Dynamics”, 4th ed., New York: McGraw-Hill, pp. 134-162, 1988.
Referring now to
Referring now to
In alternative embodiments, it is possible to derive the approximated object boundary by taking, instead of the middle point of the line segments 45 as shown in other ratios for finding the dividing point 62. Those ratios can be for example 5:95, 30:70, etc. These ratios can be defined in accordance with the intended application.
Other parameters than can be derived for each object j include the object's area, position and shape:
positionj=center of gravity of ATotal
Reference points other than the center of gravity of an object may also be derived, such as, for example, the top left corner of an object or a bounding box.
shape=ATotal
It is noted that the shape being detected is the convex hull shape of the object on the screen that excludes internal cavities of an object if those are present.
In addition to computing the boundary, area, position and shape of an object, it is also possible to calculate the object's size. The size of an object can be calculated in different ways for different geometrical figures. However, for any geometrical figure, the maximum size of the geometrical figure along the two axis, x and y, i.e., Maxx and Maxy may be determined. In most cases, the detected geometrical figure is a polygon in which case, Maxx can be defined as the maximum cross section of the resulting polygon taken along the x-axis and Maxy as the maximum cross section of the same polygon along the y-axis.
Another method for determining the size of an object is by providing a unique definition of size for a number of common geometrical shapes. For example, defining the size of a circle as its diameter, defining the size of a square as the length of one of its sides and defining the size of a rectangle as its length and width.
As described above, the present invention provides techniques for the detection of one or more objects based on the object's size and/or shape. Accordingly, for those applications that utilize objects of different sizes and/or shapes, the invention provides an additional capability of performing object recognition based on the object's detected size and/or shape.
Techniques for performing object recognition include utilizing a learning mode. In the learning mode, a user places an object on the surface of the touch screen, one at a time. The shape of the object placed on the surface of the touch screen is detected in the learning mode and object parameters including shape and size are recorded. Thereafter, in the operational mode, whenever an object is detected, its shape and size are analyzed to determine if it matches the shape and size of one of the learned objects, given an admissible deviation delta defined by the application. If the determination results in a match, then the object can be successfully identified. Examples of object recognition include recognition of pawns of a board game with a different shape or recognition of a users hand, when placed on the touch screen.
For standard shapes, such as triangle, square, etc., the standard shape parameters may be provided to the control software, so that when a similar object form is detected it can be recognized as such by the system.
Switching Schemes
According to another aspect of the present invention, different switching schemes are contemplated for switching the light transmitters on and off. A few exemplary switching schemes are described below. It is noted, however, that the described schemes are merely illustrative. The astute reader will recognize that there are many variants to the schemes described below.
A.—Plain Switching Scheme
The plain switching scheme has already been described above with reference to the illustrative embodiment. In accordance with the “plain” switching scheme, each light transmitter (e.g., L1-L15) is turned on and off in a sequence around the periphery of the touch screen 10 (
B.—Optimized Switching Scheme
Another switching scheme, which produces, in most cases, the most information about objects present on the screen early in the operational stage is referred to herein as an ‘optimized’ switching scheme. In accordance with this scheme, certain of the light transmitters are uniquely positioned in the corners of the touch screen and are directed towards the middle of the touch screen. This is a desirable positioning and orientation because a corner light transmitter lights up the entire touch screen and thus provides maximum information. The non-corner light sources, by comparison, only illuminate a part of the touch screen, thereby providing information over only a portion of the touch screen. The inventors have recognized that if the light sources which are most likely to produce the most information (i.e., the corner light sources) are used first, more information would be available at an earlier stage of the detection process. This could result in the analysis of intermediate results, which are used to adapt a subsequent switching scheme for switching the rest of the light transmitters on and off. As a consequence, it could be the case that the detection process can be completed faster and with less steps involved without having to switch all the light transmitters on and off, since sufficient information may be obtained with strategically selected transmitters. This could result in a faster response and/or energy savings.
In accordance with the optimized scheme, light transmitter L0 positioned in the upper left corner of the touch screen is switched on first since this light transmitter emits light over the total touch screen area thereby likely producing the most information. However, the optimized scheme can be started by switching any of the corner light transmitters (e.g. L0, L4, L7, L11) since they would produce equal amount of information.
Referring back to
Referring again to
In those cases where the object(s) are positioned close to L0 or L4, light transmitters L11 and L7 may be employed in addition to light transmitters L0 and L4. In the general case, minimum and maximum area estimates are calculated after light transmitter L4 is switched off, the result of which is illustrated in
In one embodiment, after the light transmitter L4 is switched off, certain of the remaining light transmitters may be strategically selected to produce maximum information to further refine the area boundaries. The particular light transmitters selected can differ in different embodiments. For example, in the present illustrative embodiment, after switching on/off light transmitters L0 and L4, the next light transmitters that can be turned are light transmitters L1 and L13 for the area on the left of the touch screen 10 and light transmitters L5 and L8 for the area on the right of the touch screen 10.
In sum, the ‘optimized’ approach allows fewer transmitters to be switched on/off in each cycle as compared to the ‘plain’ scheme. One possible advantage of the present scheme is that results can be produced earlier and more efficiently than in the previously described schemes, resulting in a faster response and thus possible energy saving in comparison to the ‘Plain’ scheme.
C.—Interactive Switching Scheme
Another scheme for switching the light transmitters is referred to as the ‘interactive’ switching scheme. The interactive scheme utilizes a strategy for switching on light transmitters based on previous detection results. Specifically, knowing the position of an object (x, y) in a previous detection cycle (or sample time) allows the light switching scheme to be adapted to target that same area in subsequent detection cycles. To account for the rest of the screen area, a simple check could be performed to insure that there are no other new objects present. This scheme is based on the assumption that an object does not substantially change its position in a fraction of a second, from one detection cycle to the next, partly due to slow human reaction times as compared to the sample times of the hardware. One possible advantage of the interactive switching scheme is that results can be produced earlier and more efficiently than in the previously described schemes, resulting in a faster response and thus possible energy saving in comparison to the ‘Plain’ scheme.
The various switching schemes can be chosen to satisfy the specific requirements for a particular intended application. By way of example, two applications are listed in table IV, (i.e., interactive café table and chess game) each requiring a different switching scheme to account for the specific requirements of the particular application.
For example, for the Interactive café table application, it may be desirable to use the ‘optimized’ switching scheme, which uses less energy by virtue of obtaining detection results using fewer light transmitters. The ‘optimized’ switching scheme may also be applicable to both applications in that they both require fast response times (see characteristic 5).
According to another aspect of the invention, multiple light transmitters (e.g., two or more) can be switched on/off simultaneously. In this manner, more information can be received in less time, resulting in a faster response of the touch screen (i.e., a faster detection result).
Energy Saving or Idle Mode
According to yet another aspect of the invention, it is contemplated that if the touch screen 10 has not detected any changes for a certain period of time, the touch screen can switch into an energy saving mode thereby reducing processing power requirements and saving on total power consumption. In the idle or energy saving mode, the number of light transmitters and sensors used in each cycle are reduced while maintaining or reducing the cycle frequency (number of cycles per second). This results in a lower total ‘on time’ of the light transmitters per cycle, which results in a lower power consumption. Also if the number of lights being switched on and off per second is reduced, the required processing power of the system will be reduced as well. As soon as a number of changes are detected, the touch frame can switch back to a normal switching scheme.
Object Identification Based on an Object's Optical Properties
In an idealized case, the object being detected is assumed to absorb 100% of the impinging light from a light transmitter. In reality, depending on the optical properties of the material that an object is made of, the light that reaches the surface of the object is partly reflected, partly absorbed and partly transmitted by the object. The amount of light reflected, transmitted (i.e., pass through) and absorbed depends on the optical properties of the material of the object and is different for different materials. As a consequence, due to these physical phenomena, two objects of identical shape but made of different materials (e.g. glass and wood) can be distinguished if differences can be detected in the amount of light reflected, absorbed and transmitted by the objects.
A.—Partial Absorption and Partial Reflection Case
B.—Total Absorption Case
C.—Partial Absorption and Partial Transmission
As described above and illustrated in
It should be appreciated that according to an advantageous aspect, because the amount of light reflected and transmitted can be detected, as was shown in the examples above, objects of identical size and shape can be distinguished if they are made of materials with different optical properties.
D.—Detection of Optical Properties for Multiple Objects
According to another aspect of the invention, the simultaneous detection of optical properties of two or more objects is considered. In this case, two or more objects can have different shapes and sizes which would make the light distribution pattern detected by the sensors rather complex if it is desired to take into account the optical properties of the objects. To resolve these complexities, pattern recognition techniques could be applied to classify objects with respect to the optical properties such as reflectivity, absorption and transmissivity of the material they are made of.
Touch Screen Shapes and Configurations
Variations in Sensor/Transmitter Density and Type
Because of the finite number of sensors in use and the fixed spacing there-between, the accuracy in determining the position, shape and size of an object is subject to uncertainty. In one embodiment, the uncertainty may be partially minimized by increasing the number of sensors used in the touch screen display 10. By increasing the number (density) of sensors, the relative spacing between the sensors decreases accordingly which leads to a more accurate calculation of the position, shape and size of an object.
In certain embodiments, the number of transmitters may be increased which also leads to a more accurate calculation of the position, shape and size of an object. It is noted that increasing the number of transmitters will highlight the object from additional angles thus providing additional information leading to more accurate results.
In certain embodiments, the overall measurement accuracy may be increased by increasing the density of transmitters and/or receivers in certain areas of the screen where detection proves to be less accurate than other areas. This non-even configuration of transmitters and/or receivers can compensate for the less accurate detection.
Overall measurement accuracy may suffer in certain situations dependent upon the position of the object on the touch screen. As such, differences in resolution and precision in detecting the location, shape and size of the object may occur. To explain these differences, three different situations are considered, (1) an object positioned in the center of the screen; (2) the same object positioned in the middle of the top edge of the screen (or any other edge); and (3) the same object positioned in the upper left corner of the screen (or any other corner of the screen).
|S2x−S1x|≦2d
As can be seen in
Referring now to
In
In a further embodiment of the present invention, a combination of different light transmitters may be used in the same application.
Referring again to
The invention has applicability to a broad range of applications, some of which will be discussed below. It should be appreciated, however, that the applications described below constitute a non-exhaustive list.
The user interaction styles (techniques) enabled by the described touch screen include:
Although this invention has been described with reference to particular embodiments, it will be appreciated that many variations will be resorted to without departing from the spirit and scope of this invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative manner and are not intended to limit the scope of the appended claims.
In interpreting the appended claims, it should be understood that:
a) the word “comprising” does not exclude the presence of other elements or acts than those listed in a given claim;
b) the word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements;
c) any reference signs in the claims do not limit their scope;
d) several “means” may be represented by the same item or hardware or software implemented structure or function;
e) any of the disclosed elements may be comprised of hardware portions (e.g., including discrete and integrated electronic circuitry), software portions (e.g., computer programming), and any combination thereof;
f) hardware portions may be comprised of one or both of analog and digital portions;
g) any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise; and
h) no specific sequence of acts is intended to be required unless specifically indicated.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2006/050728 | 3/8/2006 | WO | 00 | 9/7/2007 |
| Number | Date | Country | |
|---|---|---|---|
| 60660366 | Mar 2005 | US |
