TRIANGULATION SCHEME FOR MARKING AND ERASING DATA ENTRY DEVICE

Abstract: A movable data entry device is provided which has two output elements separated from each other. Each of the output elements are repeatably powered to send a repeated signal from the device, and power between each of the elements is toggled. As the data entry device is moved along a path on a writing area of a surface, such as a white board, a transmitted signal is alternately sent from the first output element and the second output element, and is received by two or more external receivers. Triangulation methods are used to determine the location of output elements on the movable data entry device, in relation to the writing area. The output elements are preferably ultrasonic transducers. The received signals are used to define the path and orientation of the data entry device. In a preferred embodiment, successive triangles are defined by successive locations of the two output signals. The area defined by the triangles is then used to define the path of the data entry device within the writing area. When the data entry device is used as an erasing implement, the defined triangular areas are used to erase, or remove described written symbols or paths from memory. When the data entry device is used as a marking implement, the defined path is preferably used to create calligraphic effects. Alternative embodiments allow the transmission of supplementary information from the movable implement to the receivers, using either the first and/or second output signals, such as marking or erasing or marking functions, determined pen color, stroke bias, fill color, line style, and implement user identification.

Description: TRIANGULATION SCHEME FOR MARKING AND ERASING DATA ENTRY DEVICE FIELD OF THE INVENTION The invention relates to the field of triangulation algorithms for remote devices. More particularly, the invention relates to a triangulation system for estimating the path of an electronic marking and erasing device. BACKGROUND OF THE INVENTION Digitizing pen and whiteboard systems are used for a variety of electronic applications. These systems typically include a whiteboard, a position indicating pen, and associated electronics for determining the interaction between the whiteboard and the position indicating pen. A digital data signal is typically derived to represent the relative position of the position indicating pen and the whiteboard. When a conventional marking pen is combined with a digital marking pen, a user typically writes upon a writing surface with the conventional marking pen, while a repeated digital signal defining the transcribed path of the marking implement is used to create an electronic representation of the path of the conventional marking pen. The writing tips for many conventional marking pens often provide a width and depth to the stroke of the transcribed path for a user. Thus, the transcribed path often has a calligraphic shape. In contrast, the digital signal defining the transcribed path of a movable transmitter pen typically has a uniform line width. It would be advantageous to provide a movable data entry device that provides a changing line width, providing a digital signal defining a calligraphic transcribed path of the movable data entry device. To erase a conventional marking pen path from a writing surface, a user typically uses an eraser, such as a white board eraser, and draws an erasing surface or edge of the eraser across the writing area, to remove the marked path. In one approach taken in the prior art, the user must draw an X over anything that is to be deleted. Any text or drawing object that falls within the X region will be deleted from the meeting file. The user who wants to delete the ink from the whiteboard would then follow up using a conventional eraser. It would be advantageous to provide a movable data entry device having a width, such as a marker or an eraser, that allows a user to move the device over a writing surface, creating an electronic representation of the path of the data entry device. It would also be advantageous to provide an erasing implement that also includes a conventional eraser, whereby a user can simultaneously erase an area of a writing surface, while a digital signal is produced that represents the path of the eraser, which can be used to erase or remove from memory a portion of a digital transcribed path. In addition, it would be advantageous to provide an efficient means, such as a triangulation scheme, for describing the path of the movable device. Furthermore, it would be advantageous to communicate supplementary information from the movable device. The development of such a marking and erasing data entry system and triangulation scheme would constitute a major technological advance. SUMMARY OF THE INVENTION A movable data entry device is provided which has two output elements separated from each other. The output elements, preferably but not necessarily ultrasonic transducers, are alternately powered, to send a repeated signal from the movable data entry device. As the data entry device is moved along a path on a writing area of a surface, such as a white board, a transmitted signal is alternately sent from the first output element and the second output element, and is received by two or more external receivers. Triangulation methods are used to determine the location of the output elements on the movable data entry device, in relation to the writing area. The received signals are used to define the path and orientation of the data entry device. In a preferred embodiment, successive triangles are defined by successive locations of the two output signals. Subsequent areas defined by the triangles are then used to define the path of the data entry device within the writing area. When the data entry device is used as an erasing implement, the defined triangular areas are used to erase, or remove described written symbols or paths from memory. When the data entry device is used as a marking implement, the defined path is preferably used to create a calligraphic marking path. Alternative embodiments allow the transmission of supplementary information from the movable implement to the receivers, using either the first and/or second output signals, such as erasing or marking functions, determined pen color, stroke bias, fill color, line style, and implement user identification. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a movable data entry device; Figure 2 is a block diagram for a movable data entry device; Figure 3 shows the connection between components within a movable data entry device; Figure 4 is a top view of an movable data entry device location system, in which a movable data entry device is located within a writing area, and in which the movable data entry device sends output signals to external receivers; Figure 5 is a top view showing a transcribed path for a movable data entry erasing device across a writing area, wherein the transcribed path intersects a written path; Figure 6 is a top view showing a triangulation scheme for a movable data entry device across a writing area; Figure 7 is schematic view of the transmission of a first output signal from a first output element of a movable data entry device; Figure 8 is schematic view of the transmission of a second output signal from a second output element of a movable data entry device; Figure 9 shows a shaped pulse waveform of one embodiment of a second output signal sent from a movable data entry device; Figure 10 shows an alternating output signal as it is repeatedly sent from a movable data entry device; Figure 11 shows a calculated transcribed path of a movable data entry device from sequential locations within the writing area of a surface; Figure 12 shows a movable data entry marker having a marking edge; Figure 13 shows a defined marking edge having side and radial end bias characteristics; and Figure 14 shows a defined marking edge having side bias and random end bias characteristics. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Figure 1 is a perspective view of a movable data entry device 10a. The movable data entry device 10a has a first output element 14a and a second output element 14b, which are separated by a width 18. The output elements 14a, 14b are typically housed in and extend from an implement body 12. A position switch 16 is preferably used, such that the output elements 14a, 14b are selectively powered when the movable data entry device 10a is placed against a writing surface 34,34a (FIGS. 4,5,11) by a user. Each of the output elements 14a, 14b are alternately powered to send repeated signals 36a, 36b from the movable data entry device 10. As the data entry device 10 is placed upon, and typically moved along a writing surface 34, typically by a user, the transmitted signals 36a, 36b are alternately sent from the first output element 14a and the second output element 14b, and are received by external receivers 38. Triangulation methods are used to determine the location of output elements 14a, 14b on the movable data entry device 10, in relation to the writing area 34 of a surface 12, such as a white board. The output elements 14a, 14b are preferably ultrasonic transducers. When the data entry device 10 is used as an erasing implement 10c (FIG. 5), the received signals 36a,36b are used to create an erasing path 59a (FIG. 6) for the data entry device 10. When the data entry device 10 is used as a marking implement 10d (FIG. 11), the received signals 36a,36b are used to create a marking path 59b (FIG. 11) for the data entry device 10. In a preferred embodiment, successive triangles 58a, 58b...58n (FIG. 6) are defined by successive locations of the repeated output signals 14a, 14b. Each triangle 58 is defined by three subsequent alternating output signals (e.g. 36a, 36b, 36a or 36b,36a,36b). When the data entry device 10 is used as an erasing implement 10c, adjoining successive triangles 58 are used to define an erasing path 59a (FIG. 6) within the writing area 34, to erase or remove previously defined paths 52. When the data entry device 10 is used as a marking implement 10d, the defined triangular areas 58 are used to add new defined paths 59b or written symbols 52, typically into memory 102 (FIG. 11). Figure 2 is a block diagram 20 of a movable data entry device 10b. In this embodiment, a sensor output control 22 includes a powered main printed circuit board (PCB) 24. A time toggle 26 is located between the main PCB 24 and the output sensors 14a, 14b. When the movable data entry device 10b is located away from a writing surface 34, a preferred up/down position switch 16 deactivates supply power from the sensor output control 22 to the output sensors 14a, 14b. When the movable data entry device 10b is placed upon a writing surface 34, up/down position switch 16 activates supply power from the sensor output control 22, whereby time toggle 26 alternates a supply power input pulse from the sensor output control 22 to either the first output sensor 14a or the second output sensor 14b. Figure 3 is a perspective block diagram 28 showing connections between components within a movable data entry device 10. A main central processor unit (CPU) 29 is located on the main PCB 28, and controls the operation of the movable data entry device 10. Figure 4 is a top view of a movable data entry device location system 30a, in which a movable data entry device 10 is located within a writing area 34a of a surface 32, and in which the data entry device 10 alternately sends output signals 36a, 36b to external receivers 38a, 38b. The surface 32 is typically a whiteboard, a blackboard, a drafting table, an overhead projector, or any kind of presentation surface. The calculated position and orientation of the movable data entry device 10 is represented by an (X^Y-i) position of the first output element 14a, and by an (X 2 ,Y 2 ) position of the second output element 14b, in relation to an X-axis 44 and a Y-axis 46. When the data entry device 10 is located within the writing area 34a, and is stationary, the distance between the (X- | ,Y-|) position of the first output element 14a and by the (X 2 .Y 2 ) position of the second output element 14b coincides with the width 18 (FIG. 1) between the two output elements 14a,14b. The movable data entry device 10 can be used in location systems 30 which use different types of triangulation techniques to locate the output elements 14a, 14b, such as time-of-arrival or direction-of-arrival systems. As well, while the movable data entry device 10 is described as having output sensors 14a, 14b, whereby signals are transmitted to external receivers 38, the movable data entry device 10 can also be implemented as a receiving or reflecting device, whereby signals 14a, 14b are received from external sources 38. In the embodiment 30a shown in Figure 4, the distance from the first output element 14a to the first external receiver 38a is determined by the relative time of reception of the first output signal 36a. The distance defines a circular arc 33a of possible X 1 N 1 locations for the first output element 14a of the movable data entry device 10. The distance from the first output element 14a to the second external receiver 38b is also determined by the relative time of reception of the first output signal 36a. This distance thus defines a second circular arc 35a of possible Xι,Y 1 locations for the first output element 14a of the movable data entry device 10, in relation to the second receiver 38b. In a similar manner, the (X 2 ,Y 2 ) positions of the movable data entry device 10 are calculated, as the intersection of circular arcs 33b and 35b. Hence, the (X^Y-i) and (X 2 ,Y 2 ) positions of the movable data entry device 10 are shown, and are calculated, as the intersection of possible (X- | ,Y-|) and (X 2 ,Y 2 ) locations within the writing area 34a. Figure 5 is a top view 50 showing transcribed paths 54a, 54b for the first and second output elements 14a, 14b of a movable data entry eraser 10c across a writing area 34, wherein the transcribed paths 54a, 54b intersect a written path 52. The written path 52 can be a combination of a conventional written path 52a (e.g. a marker pen ink path) and a stored electronic path 52b (e.g. a stored path from a movable data entry marker 10d (FIG. 11)). The movable data entry eraser 10c preferably has an erasing edge 51a located on a lower edge of the implement housing 12, between the first output element 14a and the second output element 14b. As a user draws the movable data entry eraser 10c across a written path 52, the erasing edge 51 erases a conventional written path 52a, while the defined erasing path 59 (FIG. 6) of the movable data entry eraser 10c is used to erase a stored electronic path 52b. Figure 6 is a top view showing a triangulation scheme 56 for a movable data entry deice 10, such as a moveable data entry eraser 10c, across a writing area 34. As a user moves the movable data entry eraser 10c across a writing area 34, the erasing edge 51 removes written paths 52a made by conventional markers. In a similar manner, the subsequent determined locations of the first and second output elements 14a, 14b are used to define an electronic removal path 59a. In this embodiment, the electronic removal path 59a is defined by successive triangles 58a, 58b...58n, which are formed by the successive locations of the repeated output signals 14a, 14b. Each triangle 58 is defined by three subsequent output signals (e.g. 36a, 36b, 36a). For example, at time t-,, the first output element 14a sends a first output signal pulse 36a; at time t 2 , the second output element 14b sends a second output signal pulse 36b, and at time t 3 , the first output element 14a again sends a first output signal pulse 36a. Triangle 58a is thereby formed by the determined location of the three subsequent pulses. At time t 4 , the second output element 14b again sends a second output signal pulse 36b, and triangle 58b is formed. Adjoining successive triangles 58 (e.g. 58a through 58f) are used to define an erasing path 59 within the writing area 34, to erase or remove previously defined electronic paths 52b. As the transmitted frequency between subsequent pulses 36a, 36b increases, the erasing path 59 formed from adjoining triangles 58 approaches the shape of the continuous path defined between transcribed paths 54a, 54b, or by the path defined by contact of the erasing edge 51 a across the writing area 34. In an alternate embodiment, the transcribed paths 54a, 54b (FIG. 5) for the first and second output elements 14a, 14b are defined by fitting subsequent (X-I .Y-I) positions of the first output element 14a to an estimated first transcribed path 54a, and by fitting subsequent (X 2> Y 2 ) positions of the second output element 14b to an estimated second transcribed path 54b. In this embodiment, the electronic removal path 59a is defined between the first transcribed path 54a and the second transcribed path 54b. Output Signal Transmission. Figure 7 is a schematic view 60a of the transmission of a first output signal 36a from a first output element 14a of a movable data entry device 10. Figure 8 is a schematic view of the transmission 60b of a second output signal 36b from a second output element 14b of a movable data entry device 10. As discussed above, the sensor output control source 22, typically using a time toggle 26, alternately powers the first output element 14a and the second output element 14b. The first and second output signals 36a, 36b are preferably ultrasound output signals 36, which are transmitted from ultrasound transducers 14a, 14b located on the movable data entry device 10. In one embodiment, the ultrasound transducers 14 each comprise a cylindrical layered piezoelectric layer 68 surrounded by an outer conductive layer 66a and an inner conductive layer 66b, which is connected to the sensor output control source 22 by leads 62a and 62b and lead connections 64a and 64b. In another embodiment, the ultrasound transducers 14a, 14b used are Part No. AT/R 40-1 OP, manufactured by Nippon Ceramic Co. Ltd., of Tottori-Shi, Japan. The power required to alternately transmit signals 36a,36b from the output elements 14a, 14b is low, which allows the movable data entry device 10 to be operated as a remote, untethered device 10. Figure 9 shows a shaped pulse waveform 70 of one embodiment of a second output signal 36 sent from a movable data entry device 10. While an ultrasound second output signal 36 can have any waveform shape, including a single ultrasound pulse 72, it is preferred that the waveform 36 be shaped to have a short duration, with distinctive wave characteristics. Shaped waveforms 70 allow the output signals 36a,36b to be measured and compared accurately, to provide accurate calculated (X-|,Y-|) and (X 2 ,Y 2 ) locations for the movable data entry device 10 within the writing area 34a on a frequent basis. In the preferred embodiment shown in Figure 9, the subsequent output signal 36 includes two major pulses 72a and 72b, with specific timing between them. The short duration output signals 36 allow the movable data entry device 10 to send sequential output signals 36a, 36b more frequently. The use of the short duration ultrasound output signals 36a,36b with distinctive waveform characteristics 72a,72b also allows the transmission of other information to be sent from the movable data entry device 10 to the external receivers 38, as discussed below. While there are commonly differences between the received amplitude of the subsequent output signals 36a,36b, typically from signal attenuation, each of the signals 36 retains major features, such as waveform characteristics 72a,72b, as well as wavelength dependent features, such as peaks 76a, 76b, 76c, and 76d, which allows comparison of these features between subsequent output signals 36a, 36b. Movable Data Entry Device Location Algorithm. The accuracy of the location of the first output element 14a and the second output element 14b of the movable data entry device 10 is dependent on the accuracy with which the signal processor 94 (FIG. 11) connected to the receivers 38 can consistently determine the distance in time between repeatable reference points 77 of the output signal waveform 70. Any repeatable reference point 77 on the output ultrasound signal waveform 36 is sufficient to compare subsequent output signal waveforms 70, as long as the repeatable reference point 77 is consistently identified. In Figure 9, the crossing time threshold 73 indicates a starting point for the repeated ultrasound output signals 36. In embodiments where an ultrasound output signal 36 is used, it is preferred to use a linearly decaying ultrasound threshold 73, since the amplitude of the ultrasound signal 36 falls off like 1/r with distance. At times t A , t B ,...t N , where N equals the number of receivers 38 (where N > 2), the ultrasound signal 36 is received at two or more external receivers 38 A , 38{3, ...38N. The signal processor 94 finds a repeatable reference point 77 on the ultrasound output signals 36a, 36b, which in one embodiment lies between the threshold crossing 73 and one of the peaks 76. In Figure 9, a threshold value 75 of 0.5 volts is used to determine points along the subsequent output signals 36. As seen in Figure 9, the first point along the output signal 36 to cross the threshold value is located along the first peak 76a. In contrast, the first point along a subsequent output signal 36 to cross the threshold value 75 may be located along a different peak 76, such as the second peak 76b. Since subsequent output signals 36a, 36b typically have different amplitudes, commonly due to signal attenuation, the arbitrary measurement of a threshold 75 to determine a reference point 77 can yield differences between subsequent signals 36 on the order of a wavelength. To provide a more accurate repeatable reference point 77 on the present ultrasound output signal 36 that lies between the threshold crossing 73 and the second peak 76b, the signal processor 94 compares repeatable features between the subsequent output signals 36. Repeatable features that are distinguishable typically include the shape of major peaks 72a, 72b and minor peaks 76a, 76b, interpeak spacing, and the relative amplitude of the major peaks 72a, 72b and minor peaks 76a, 76b. Any or all features between subsequent output signals 36 can be analyzed and compared, to determine an accurate repeatable reference point 77. Even the combined relationship between sets of features can be compared. In a preferred embodiment, the current output signal 36 and one or more stored prior output signals 36 are energy-normalized, such that individual peaks 72, 76 are fit to each other between the current output signal 36 and the stored prior output signals 36. The normalized output signals are then compared for features that do not depend on the amplitude of separate points on the signals 36a, 36b, but on the relationship between features. In the example shown in Figure 9, the signal processor 94 adjusts the actual threshold crossing on peak 76b on the present output signal 36 by the period of one wavelength, to establish an adjusted threshold crossing 77 that is consistent with the features of another signal 36. In this manner, the signal processor 94 typically uses a previously received and stored pulse 36a or 36b, from the same receiver 38a or 38b, to determine the repeatable reference point 77 on the current ultrasound signal 36. The current ultrasound signals 36a,36b for each receiver 38, together with the detected start of the signal reference points 73 and repeatable points 77, are then preferably stored within memory 102 for analysis of subsequent output signals 36. For each receiver 38, a plurality of prior signals 36a, 36b with reference points 73,77, can be used to determine repeatable features 77 of the current output signal 36. However, a limited number of previous ultrasound signals 36a,36b from each receiver 18 are typically stored, to conserve memory space within memory 102. This is repeated for all N receivers 38, giving N>2 estimates of the time of propagation of the output ultrasound signals 36a,36b. The N>2 second output signals 36, along with associated reference points 73,77, are then preferably stored within memory 102 as prior output signals 36a,36b for the analysis of subsequent second output signals 36a,36b. The comparison of the currently received output signals 36a,36b to previously received and stored output signals 36a, 36b results in consistent time values, which yield consistent movable data entry device (X^ Y-,) and (X 2 Υ 2 ) location values, which define a smooth erasing path 59a (FIG. 6) or marking path 59b (FIG. 11). After the time of arrival values t A , t B are calculated for each arriving output signal 36 at receivers 38a, 38b, the signal processor 94 calculates the X and Y position from the time of arrival values t A and t B , using standard trigonometric calculations, such as: x = (t A * t A )+(d * d)-(t A * t A ); (1) x = x/(2*W); and (2) y = sqrt (t A V(xW); (3) in which W (FIG. 4) is the distance between receivers 38, in units of time taken for the ultrasound signal 36 to travel from one receiver 38 to another receiver 38. Figure 10 shows an alternating output signal pulse train 80 as it is repeatedly sent from a movable data entry device 10. A first output signal 36a and a second output signal 36b are repeatedly transmitted from the movable data entry device 10, typically in a periodic manner, whereby a first period Pi 82 is defined between subsequent first and second output signals 36a and 36b, and whereby a second period P 2 84 is defined between subsequent first output signals 36a, or between subsequent second output signals 36b. The output signals 36a,36b arrive at the external receivers 38 at a time which is dependent on the velocity of the output signals 36a,36b. Movable Data Entry Device Marking System. Figure 11 is a top view 80 of a movable data entry device system 30b, in which a movable data entry marker 10d is located within a writing area 34 of a surface 32, and in which the data entry marker 10d alternately sends output signals 36a, 36b to external receivers 38. A calculated transcribed marking path 59b is defined by the signal processor 94, as a movable data entry marker 10d is moved across the writing area 34 of a surface 32. When the first output signals 36a and the second output signals 36b arrive at each of the receivers 38, the signals 36a, 36b are sampled, and are then transferred to the signal processor 94, through a wired or wireless connection 92. The locations of the first output element 14a and the second output element 14b of the movable data entry marker 10d, in relation to a defined X-axis 44 and a Y- axis 46, are then determined by the signal processor 94. The signal processor 94 solves for calculated distances from the output elements 14a, 14b to each of the receivers 38 using the output signals 36a, 36b, and then determines subsequent locations of the first output element 14a and the second output element 14b, based on the calculated distances to the receivers 38. The defined locations of the output elements 14a, 14b are then stored 102 or transferred by the signal processor 94 to computer 96, which typically includes a graphic user interface (GUI) 100.. In a preferred embodiment, a programmable control application 98 within the computer 96 communicates with the signal processor 94, to control system options, such as erasing path 59a or marking path 59b algorithms, and erasing path 59a or marking path 59b storage or transfer options. Since the output signals 36a,36b are captured and stored in a digital manner, operation of the system is efficiently monitored or modified through the programmable control application software 98. Movable Data Entry Device Location and Path Detection Process. The movable data entry device location process, which uses the first and second output signals 36 to locate the movable data entry device 10 relative to the writing area 34 of a surface 32, comprises the following steps: i) alternately sending a first output signal 36a from a first output element 14a and a second output signal 36b from a second output element 14b of a movable data entry device 10 repeatedly to a plurality of external receivers 38; ii) determining the location of the first output element 14a and the location of the second output element 14b based on the received output signals; and iii) defining the path of the movable data entry device 10 based upon subsequent determined locations of the first output element 14a and the second output element 14b. Communication of Supplementary Information. As discussed above, the output signal characteristics of the circuitry 22 and the highly defined characteristic transmitter output signals 36 can optionally communicate secondary information to the external receivers 38. Such supplementary information can include device activation status (such as through up/down switch 16), or device types, such as marking or erasing options, determined pen color, stroke bias, fill color, line color, width, and implement user identification. In systems where more than one user is writing or erasing on the writing area 34 of the surface 32, either sequentially of concurrently, different movable data entry devices 10 can optionally communicate the designated user of each movable data entry device 10. Movable data entry devices 10 can optionally include circuitry 22 for a given device "type", or can include switching or continuous adjustment control to produce output signals 36a, 36b for different device attributes. For example, a movable data entry device 10 used as an eraser 10c can be used in a system 30 which uses another, similar movable data entry device 10 as a marker 10d, or with a transmitter pen having a single output element 14. For the movable data entry marker 10d, the output signals 36a, 36b sent from the marker 10d may include a waveform which defines a color of ink, such as black ink. For a movable data entry eraser 10c, the output signals 36a, 36b sent from the eraser 10c may include a waveform which defines an "erasing" color of ink, such as "clear" ink, which defines an erasing function, whereby the signals 36a,36b sent to the external receivers 38a are recognized as belonging to an eraser 10c. In another embodiment, a single movable data entry device 10 can be selectively adjusted by the user, either to produce output signals 36a,36b that correspond to drawn paths 52b of varying colors, widths, or line styles, or to produce output signals 36a,36b that correspond to erasing paths 59a. While the user draws or writes upon a writing surface 14 of a surface 12, such as a white board 12, displaying a black path 52 (FIG. 5,11), such as figures or letters, the transmitted and processed signal for the path 82 is dependent upon the pen characteristics or erasing characteristics chosen by the user. Figure 12 is a side view a movable data entry marker 10d having a marking edge 51 b. When the movable data entry marker 10d is placed upon a writing area 34, the marking edge 51b comes into contact with the surface on line 106. As the movable data entry marker 10d moves along the surface 34, transcribed paths 54a and 54b are defined at the periphery of the defined path 59b. Figure 13 shows a defined marking edge 106 having side bias 108a and round end bias 108b characteristics. Figure 14 shows a defined marking edge 106 having side bias 108a and a random end bias 108c characteristics. When signals 36a, 36b are output from output elements 14a, 14b, the defined marking path 59b or erasing path 59a are not necessarily limited to just the triangular areas 58 (FIG. 6) defined between subsequent points. The defined path 59 can include characteristics, such as side bias 108a, round end bias 108b, and random edge bias 108c, which allow the movable data entry device 10 to define unique marking or erasing paths 59, similar to the use of a spray gun, air brush, or paint brush. Although the movable data entry device location system 30, triangulation schemes, and methods of use are described herein in connection with computer input systems, the techniques can be implemented for other control or display devices, or any combination thereof, as desired. As well, while the movable data entry device 10 is described using two output elements 14a, 14b, any number of output elements 14 may be used. Accordingly, although the invention has been described in detail with reference to a particular preferred embodiment, persons possessing ordinary skill in the art to which this invention pertains will appreciate that various modifications and enhancements may be made without departing from the spirit and scope of the claims that follow.

Claims: CLAIMS What is claimed is: 1. A data entry device, comprising: a first output element; a second output element separated from said first output element; and means for alternately powering said first output element to transmit a first output signal, and said second output element to transmit a second output signal. 2. The data entry device of Claim 1 , wherein said first output element and said second output element are ultrasonic transducers. 3. The data entry device of Claim 1 , wherein said first output element and said second output element are piezoelectric transducers. 4. The data entry device of Claim 1 , further comprising: a switch for activating said means for alternately powering said first output element and said second output element. 5. The data entry device of Claim 1 , further comprising: a marking edge between said first output element and said second output element. 6. The data entry device of Claim 1 , further comprising: an erasing edge between said first output element and said second output element. 7. The data entry device of Claim 1 , further comprising: means for determining the locations of said first output element and said second output element in relation to a surface. 8. The data entry device of Claim 7, wherein said means for determining said locations of said first output element and said second output element is programmable. 9. The data entry device of Claim 1 , wherein said first output signal contains encoded information regarding said data entry device. 10. The data entry device of Claim 1 , wherein said second output signal contains encoded information regarding said data entry device. 11. The data entry device of Claim 10, wherein said encoded information includes a determined color of said data entry device. 12. The data entry device of Claim 10, wherein said encoded information includes a determined line width of said data entry device. 13. The data entry device of Claim 10, wherein said encoded information includes a user identification of said data entry device. 14. A location system, comprising: a surface having a writing area, a plurality of receivers, and a signal processor; a movable device locatable upon said writing area of said surface, said movable device having a first output element for sending a first output signal from said movable device to said plurality of receivers, a second output element separated from said first output element for sending a second output signal from said movable device to said plurality of receivers, a sensor output for alternately powering said first output element and said second output element; and a signal processor connected to each of said plurality of receivers, which processes said first output signal and said second output signal to calculate said location of said first output element and said second output element. 15. The location system of Claim 14, wherein said first output element and said second output element are ultrasonic transducers. 16. The location system of Claim 14, wherein said first output element and said second output element are piezoelectric transducers. 17. The location system of Claim 14, further comprising: a switch for activating said sensor output for alternately powering said first output element and said second output element. 18. The location system of Claim 14, further comprising: a marking edge between said first output element and said second output element. 19. The location system of Claim 14, further comprising: an erasing edge between said first output element and said second output element. 20. The location system of Claim 14, further comprising: means for determining location of said first output element and said second output element in relation to said writing area. 21. The location system of Claim 20, wherein said means for determining location of said first output element and said second output element is programmable. 22. The location system of Claim 14, wherein said first output signal contains encoded information regarding said movable device. 23. The location system of Claim 14, wherein said second output signal contains encoded information regarding said movable device. 24. The location system of Claim 23, wherein said encoded information includes a determined color of said movable device. 25. The location system of Claim 23, wherein said encoded information includes a determined line width of said movable device. 26. The location system of Claim 23, wherein said encoded information includes a user identification of said movable device. 27. A process for calculating a path of a movable data entry device relative to a surface, comprising the steps of: alternately transmitting a first output signal from a first output element on said movable data entry device, and a second output signal from a second output element on said movable data entry device, wherein first output element and said second output element are separated by a width; alternately determining a location of said first output element and a location of said second output element based on said transmitted output signals; and defining said path of said movable data entry device based upon subsequent determined locations of said first output element and said second output element. 28. The process of Claim 27, wherein said first output element and said second output element are ultrasonic transducers. 29. The process of Claim 27, wherein said first output element and said second output element are piezoelectric transducers. 30. The process of Claim 27, wherein said step of defining said path of said movable data entry device is based upon at least one triangular area defined from said subsequent determined locations of said first output element and said second output element. 31. The process of Claim 27, further comprising the step of: selectively powering said alternate transmission of said first output signal and said second output signal, whereby said first output signal and said second output signal are alternately transmitted when said movable data entry device is located on said surface, and whereby said first output signal and said second output signal are not alternately transmitted when said movable data entry device is located away from said surface. 32. The process of Claim 27, further comprising the step of: providing a marking edge between said first output element and said second output element. 33. The process of Claim 27, further comprising the step of: providing an erasing edge between said first output element and said second output element. 34. The process of Claim 27, further comprising the step of: providing a means for determining location of said first output element and said second output element in relation to said surface. 35. The process of Claim 34, wherein said step of alternately determining said location of said first output element and said location of said second output element is programmable. 36. The process of Claim 27, wherein said first output signal and said second output signal contain encoded information regarding said data entry device. 37. The process of Claim 36, wherein said encoded information includes a determined color of said data entry device. 38. The process of Claim 36, wherein said encoded information includes a determined line width of said data entry device. 39. The process of Claim 36, wherein said encoded information includes a user identification of said data entry device.

Inventors: HOLTZMAN RAFI, HOLTZMAN, RAFI
Applicants: ELECTRONICS FOR IMAGING INC, ELECTRONICS FOR IMAGING, INC.
Application year: 1999
Main classification: G06K11
IPC codes: G06F3