Patent Application
20060274906
The present invention relates to the field of acoustic sensors. More specifically, the present invention relates to an acoustic sensor with combined frequency ranges.
Acoustic data can be used in computers and consumer electronics for a variety of purposes. For example, video conferencing and virtual meeting technology often include microphones to capture audible acoustic data, such as the voices of the participants, so that the audible data can be provided along with video data and/or graphical data to the other participants. Audible acoustic data can also be used to record sounds such as speech and music, capture dictation and convert it to text, detect and track the location of a speaker in a room in order to automatically focus a camera on that individual, and countless other applications.
In addition to audible acoustic data, ultrasonic acoustic data can also have a number of uses. An ultrasonic (US) pen is one example. Some US pens can be used like a regular pen to write on a surface, such as a piece of paper or a whiteboard. At the same time however, the motion of the pen can be tracked using a combination of acoustics and electronics to capture the pen's motion.
US pen technology has many applications. For example, as a user writes on a surface, an image of the writing can be captured and shown on a computer display. This can be particularly useful in video conferences and virtual meetings. For instance, as a speaker writes notes on a whiteboard during a meeting, the writing can be displayed on computer screens for participants in the room as well as those located remotely.
As another example, in addition to capturing an image of what is written on a surface, a US pen can also be used to move a mouse pointer in a graphical user interface. This can also be particularly useful during video conferences and virtual meetings. For instance, presentations are commonly assembled on a computer and then projected onto a wall or screen, as well as provided to remote viewers through network connections. With a US pen, a person can interact with the presentation directly from the image projected onto the screen. That is, the person can move the pen over the screen's surface, and the system can capture the motion of the pen and move an image of a mouse pointer on the screen, as well as the displays of the remote viewers, to track the pen's motion. These are just two examples of the many ways in which US pen technology can be used.
Examples of the present invention are illustrated in the accompanying drawings. The accompanying drawings, however, do not limit the scope of the present invention. Similar references in the drawings indicate similar elements.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, those skilled in the art will understand that the present invention may be practiced without these specific details, that the present invention is not limited to the depicted embodiments, and that the present invention may be practiced in a variety of alternative embodiments. In other instances, well known methods, procedures, components, and circuits have not been described in detail.
Parts of the description will be presented using terminology commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. Also, parts of the description will be presented in terms of operations performed through the execution of programming instructions. It is well understood by those skilled in the art that these operations often take the form of electrical, magnetic, or optical signals capable of being stored, transferred, combined, and otherwise manipulated through, for instance, electrical components.
Various operations will be described as multiple discrete steps performed in turn in a manner that is helpful for understanding the present invention. However, the order of description should not be construed as to imply that these operations are necessarily performed in the order they are presented, nor even order dependent. Lastly, repeated usage of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may.
Since both audible and ultrasonic acoustic data have so many useful applications, it would be beneficial to have an acoustic sensor that can receive both types of acoustic data. The frequency range of audible sound tends to be from about zero to 20 KHz. Different ultrasonic applications, tend to use different ranges of ultrasonic frequency. For instance, one brand of ultrasonic pen may use a signal in the 40 KHz to 50 KHz range, and another brand may use a signal in the 80 KHz to 90 KHz range. The frequency range of ultrasonic sound is generally considered to be about 40 KHz to 100 KHz. So, an ultrasonic sensor that can support a variety of ultrasonic applications would likely need to be able to detect the entire ultrasonic range from 40 KHz to 100 KHz. Adding the audible range to the ultrasonic range to support both audible and ultrasonic applications, and the combined range of useful acoustic data may extend from zero to 100 KHz.
Acoustic sensors with 100 KHz of bandwidth may exist, but these broadband sensors tend to be excessively expensive for use in the competitive computer and consumer electronics market. Furthermore, many applications of acoustic data use arrays of multiple sensors, making the use of broadband sensors even more cost prohibitive.
Embodiments of the present invention can combine the bandwidths of less expensive sensors to provide a hybrid sensor that can be considerably less expensive than existing broadband sensors, while providing the same or similar total effective bandwidth. Although embodiments of the present invention will be primarily described in the context of a hybrid sensor for combining the ultrasonic and audible frequency ranges, other embodiments of the present invention can similarly combine virtually any number of virtually any frequency ranges into a hybrid sensor.
Sensor array 130 can include a number of hybrid sensors 160 positioned along an edge of writing surface 120. Each sensor 160 may be able to receive ultrasonic signal 150. The signal that is captured by each sensor 160 can comprise a separate channel of acoustic data. The illustrated embodiment includes 12 sensors 160, which means the illustrated embodiment can capture up to 12 channels of acoustic data. Each channel of data can be converted to a series of data samples and the samples can be synchronously interleaved. That is, a data sample from channel 1 can be followed by a data sample from channel 2, which can be followed by a data sample from channel 3, and so on up to channel 12. The pattern can repeat, interleaving data samples from channels 1 through 12 at some periodic rate.
The 12 channels of data can be provided to a host device through a communications medium. In the illustrated embodiment, the host device is a notebook computer 105 and the communications medium is a universal serial bus (USB) cable 115. Notebook 105 may include a keyboard 125 and a display 135 for displaying a graphical user interface (GUI). The 12 channels of data can be used by notebook 105 to control the position of a pointer 145 in display 135 and/or capture and display drawing 140.
For instance, since the distance from pen 110 to any pair of sensors 160 is likely to be different, the amount of time that signal 150 takes to reach the pair of sensors is likely to be different. This propagation delay between two channels of acoustic data, along with the speed of sound and the relative locations of the two sensors, can be used to calculate a position of pen 110. In other words, various algorithms can be used to triangulate a position of the pen and track the pen's motion as the position changes over time.
Since the sensors 160 are hybrid sensors, they may also be able to receive audible acoustic data. For instance, sensor array 130 may be able to capture a user's voice. With 12 channels of data, a variety of applications could use the data for noise cancellation, speaker tracking, and the like.
In the illustrated example, hybrid sensor 160 also includes two digital filters, a low pass filter 250 and a high pass filter 260. Low pass filter 250 can filter out data in the stream of digital samples corresponding to higher frequencies, and provide a stream of digital data samples 270 representing the audible data. High pass filter 260 can do just the opposite to provide a stream of digital data samples 280 representing the ultrasonic data.
Hybrid sensor 160 can be considerably less expensive than a single, broadband sensor capable of detecting both the audible and ultrasonic acoustic ranges because the cost of an acoustic sensor tends to increase dramatically at higher bandwidths. In other words, the cost of a microphone with a 20 KHz bandwidth, a microphone with a 60 KHz bandwidth, plus an analog mixer can be considerable less than a 100 KHz bandwidth microphone.
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Frequencies between 20 KHz and 40 KHz may not be captured by the hybrid sensor in this particular example. But, data in that frequency range may not be needed by the set of applications that use this particular hybrid sensor. For example, as shown in
At 660, the stream of data samples can be low-passed filtered into a stream of digital data samples representing a bandwidth of acoustic data at lower frequencies. At 670, the lower frequency data can then be interleaved with similar lower frequency data streams from other hybrid sensors in a sensor array, and supplied to an audio tracking unit in a host device.
At 680, the stream of data samples can be high-passed filtered into a stream of digital data samples representing a bandwidth of acoustic data at higher frequencies. At 690, the higher frequency data can then be interleaved with similar higher frequency data streams from the other hybrid sensors in the sensor array, and supplied to an ultrasonic pen unit in the host device.
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Certain embodiments may include additional components, may not require all of the above components, or may combine one or more components. For instance, temporary memory 720 may be on-chip with processor 710. Alternately, permanent memory 740 may be eliminated and temporary memory 720 may be replaced with an electrically erasable programmable read only memory (EEPROM), wherein software routines are executed in place from the EEPROM. Some implementations may employ a single bus, to which all of the components are coupled, while other implementations may include one or more additional buses and bus bridges to which various additional components can be coupled. Similarly, a variety of alternate internal networks could be used including, for instance, an internal network based on a high speed system bus with a memory controller hub and an I/O controller hub. Additional components may include additional processors, a CD ROM drive, additional memories, and other peripheral components known in the art.
Various functions of the present invention, as described above, can be implemented using one or more of these hardware systems. In one embodiment, the functions may be implemented as instructions or routines that can be executed by one or more execution units, such as processor 710, within the hardware system(s). As shown in
In alternate embodiments, various functions of the present invention may be implemented in discrete hardware or firmware. For example, one or more application specific integrated circuits (ASICs) could be programmed with one or more of the above described functions. In another example, one or more functions of the present invention could be implemented in one or more ASICs on additional circuit boards and the circuit boards could be inserted into the computer(s) described above. In another example, one or more programmable gate arrays (PGAs) could be used to implement one or more functions of the present invention. In yet another example, a combination of hardware and software could be used to implement one or more functions of the present invention.
Thus, an acoustic sensor with combined frequency ranges is described. Whereas many alterations and modifications of the present invention will be comprehended by a person skilled in the art after having read the foregoing description, it is to be understood that the particular embodiments shown and described by way of illustration are in no way intended to be considered limiting. Therefore, references to details of particular embodiments are not intended to limit the scope of the claims.
