TOUCH SCREEN
A method for determining the location of an object on a touch panel is provided. Initially, a pulse of terahertz radiation is transmitted through a touch panel, which formed of a dielectric material such that the pulse generates a evanescent field in a region adjacent to a touch surface of the touch panel. A reflected pulse is generated by an object located within the region adjacent to the touch surface of the touch panel, and a position of the object on the touch surface of the touch panel is triangulated at least in part from the reflected pulse.
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The invention relates generally to a touch screen and, more particularly, to a terahertz-enabled touch screen.
BACKGROUNDTouch screens have become ubiquitous, being included in mobile devices (i.e., phones) and other devices (i.e., tablet computers). There is however difficulty in engineering larger displays (such as for “black boards). Resistive and capacitive touch panels for large scale applications can be expensive and “power hungry,” while projector based solutions suffer from occlusion. Thus, there is a need for a touch sensitive system that is scalable.
Some examples of conventional circuits and systems are: Williams, “Filling the THz Gap,” doi:10.1088/0034-4885/69/2/R01; Heydari et al., “Low-Power mm-Wave Components up to 104 GHz in 90 nm CMOS,” ISSCC 2007, pp. 200-201, February 2007, San Francisco, Calif.; LaRocca et al., “Millimeter-Wave CMOS Digital Controlled Artificial Dielectric Differential Mode Transmission Lines for Reconfigurable ICs,” IEEE MTT-S IMS, 2008; Scheir et al., “A 52 GHz Phased-Array Receiver Front-End in 90 nm Digital CMOS” JSSC December 2008, pp. 2651-2659; Straayer et al. “A Multi-Path Gated Ring Oscillator TDC With First-Order Noise Shaping,” IEEE J. of Solid State Circuits, Vol. 44, No. 4, April 2009, pp. 1089-1098; Huang, “Injection-Locked Oscillators with High-Order-Division Operation for Microwave/Millimeter-wave Signal Generation,” Dissertation, Oct. 9, 2007; Cohen et al., “A bidirectional TX/RX four element phased-array at 60 HGz with RF-IF conversion block in 90 nm CMOS processes,” 2009 IEEE Radio Freq. Integrated Circuits Symposium, pp. 207-210; Koh et al., “A Millimeter-Wave (40-65 GHz) 16-Element Phased-Array Transmitter in 0.18-μm SiGe BiCMOS Technology,” IEEE J. of Solid State Circuits, Vol. 44, No. 5, May 2009, pp. 1498-1509; York et al., “Injection- and Phase-locking Techniques for Beam Control,” IEEE Transactions on Microwave Theory and Techniques, Vol. 46, No. 11, November 1998, pp. 1920-1929; Buckwalter et al., “An Integrated Subharmonic Coupled-Oscillator Scheme for a 60-GHz Phased Array Transmitter,” IEEE Transactions on Microwave Theory and Techniques, Vol. 54, No. 12, December 2006, pp. 4271-4280; PCT Publ. No. WO2009028718; and U.S. Pat. No. 3,673,327.
SUMMARYAn embodiment of the present invention, accordingly, provides a method. The method comprises transmitting a pulse of terahertz radiation through a touch panel formed of a dielectric material such that the pulse generates a evanescent field in a region adjacent to a touch surface of the touch panel; generating a reflected pulse from an object located within the region adjacent to the touch surface of the touch panel; and triangulating a position of the object on the touch surface of the touch panel at least in part from the reflected pulse.
In accordance with an embodiment of the present invention, the step of triangulating further comprises: receiving the reflected pulse by a first receiver and a second receiver that are separated from one another by a distance; and calculating the position of the object based at least in part on a first elapsed time between transmission and reception at the first receiver, a second elapsed time between transmission and reception at the second receiver, and the distance.
In accordance with an embodiment of the present invention, the reflected pulse further comprises a first reflected pulse, and wherein the step of triangulating further comprises: generating a second reflected pulse from a reflector included in the touch panel; receiving the first and second reflected pulses by a receiver; and calculating the position of the objected from the first and second reflected pulses.
In accordance with an embodiment of the present invention, the reflector is located along the periphery of the touch panel.
In accordance with an embodiment of the present invention, the pulse further comprises a first pulse, and wherein the reflected pulse further comprises a first reflected pulse, and wherein the first pulse is transmitted by a first transceiver, and wherein the method further comprises: transmitting a second pulse of terahertz radiation through a touch panel by a second transceiver; and generating a second reflected pulse from an object located within the region adjacent to the touch surface of the touch panel.
In accordance with an embodiment of the present invention, the step of triangulating further comprises triangulating the location of the object on the touch surface of the touch panel from the first and second reflected pulses.
In accordance with an embodiment of the present invention, an apparatus is provided. The apparatus comprises a touch panel formed of a dielectric material that is configured to carry terahertz radiation and having a touch surface; and a touch controller that is optically coupled to touch panel, wherein the touch controller is configured to transmit a pulse of terahertz radiation through the touch panel so as to generate a evanescent field in a region adjacent to the touch surface, and wherein the touch controller is configured to receive a reflected pulse that is generated by an object located within the region, and wherein the touch controller is configured to triangulate a position of the object on the touch surface at least in part from the reflected pulse.
In accordance with an embodiment of the present invention, the touch controller further comprises: a signaling circuit that is configured to generate and receive terahertz radiation; and a control circuit that is coupled to the signal circuit.
In accordance with an embodiment of the present invention, the signaling circuit further comprises: a transceiver; a local oscillator that is coupled to the transceiver; and a receiver circuitry that is coupled to the transceiver.
In accordance with an embodiment of the present invention, the receiver circuitry further comprises an analog baseband circuit that averages the combined signal for a plurality of sampling periods within a digitization window to generate a plurality of averaged signals and that converts the plurality of averaged signals to a digital signal.
In accordance with an embodiment of the present invention, the analog baseband circuit further comprises: a clock circuit; a low noise amplifier (LNA) that is coupled to the summing circuit; an averager that is coupled to the LNA and the clock circuit; an analog-to-digital converter (ADC) that is coupled to the LNA and the clock circuit; and an output circuit that is coupled to the ADC.
In accordance with an embodiment of the present invention, the transmitter further comprises: a transmitter that is coupled to the local oscillator; and a plurality of receivers that are spaced apart from one another and that are each coupled to the receiver circuitry.
In accordance with an embodiment of the present invention, the touch panel further comprises a reflector.
In accordance with an embodiment of the present invention, a method is provided. The method comprises transmitting a pulse of terahertz radiation through a touch panel formed of a dielectric material such that the pulse generates a evanescent field in a region adjacent to a touch surface of the touch panel; generating a plurality of reflected pulses, wherein a first reflected pulse is generated by a object located within the region adjacent to the touch surface of the touch panel; and triangulating a position of the object on the touch surface of the touch panel at least in part from the plurality of reflected pulses.
In accordance with an embodiment of the present invention, the object further comprises a first object, and wherein the position further comprises a first position, and wherein a second reflected pulse of the plurality of reflected pulses is generated by a object located within the region adjacent to the touch surface of the touch panel and at a second location.
In accordance with an embodiment of the present invention, the step of triangulating further comprises: receiving the plurality of reflected pulses by a first receiver and a second receiver that are separated from one another by a distance; and calculating the position of the object based at least in part on the plurality of reflected pulses.
In accordance with an embodiment of the present invention, a third reflected pulse of the plurality of reflected pulses is generated by a reflector.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Refer now to the drawings wherein depicted elements are, for the sake of clarity, not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views.
This application incorporated by reference co-pending U.S. patent application Ser. No. 12/871,626, entitled “DOWNCONVERSION MIXER,” filed on Aug. 30, 2010; co-pending U.S. patent application Ser. No. 12/878,484, entitled “TERAHERTZ PHASED ARRAY SYSTEM,” filed on Sep. 9, 2010; and co-pending U.S. patent application Ser. No. 12/871,626, entitled “ANALOG BASEBAND SYSTEM FOR A TERAHERTZ PHASED ARRAY SYSTEM,” filed on Apr. 12, 2011.
Turning to
Because terahertz radiation exhibits optical behavior, it can be transmitted through the touch panel 102 in a similar manner infrared radiation being transmitted through an optical fiber. As a result, the terahertz radiation generates an evanescent field in an evanescent field region 114 that is adjacent to the touch surface of the touch panel 102. When transmitted through fibers or other transmission media, infrared, visible spectrum, and ultraviolet radiation also generate an evanescent field in an evanescent field region, but this region for infrared, visible spectrum, and ultraviolet radiation is much smaller than evanescent field region 114 because of the frequencies. Thus, because the evanescent field region 114 is so much larger, it is much easier for interference within this region 114 to be detected, which can be seen in
In the example shown in
Turning to
In operation, phased array system 200 (which is generally incorporated into an integrated circuit or IC) can generate a short range radar system that operates in the terahertz frequency range (which is generally between 0.1 THz and 10 THz). To accomplish this, local oscillator 202 generates a high frequency signal FL01 that is on the order of tens to hundreds of gigahertz (i.e., 40 GHz, 50 GHz, 67 GHz, and 100 GHz.) and a pulse signal TPUSLE. The distribution network 226 then provides signal FL01 to each of the transceivers 204-1 to 204-N such that the signals received by each of transceivers 104-1 to 204-N are substantially in-phase. A controller 208 provides a control signal to array 224, which phase-adjusts the transceivers 204-1 to 204-N with respect to one another to direct a beam of terahertz frequency radiation. The transceivers 204-1 to 204-N can then receive reflected radiation back from a target, which is provided to summing circuit 210. The output of summing circuit 210 is the converted to a digital signal by a mixer 212, amplifier 214, filter 216, switches 218-1 to 218-N, variable selector 220, and ADCs 222-1 to 222-N. Additionally, mixer 212 can receive a divided signal from LO 202 (i.e., FL01/2 or another synthesized signal) or can be removed (typically for 40 GHtz or less).
Generally, this phased array system 200 has several different types of operational modes: pulsed, continuous, and stepped frequency. For a pulsed operational mode, a pulse of terahertz radiation is directed toward a target. The continuous operational mode uses a continuously generated beam, which is generally accomplished by effective “shutting off” the pulse signal TPULSE. Finally, stepped frequency allows to frequency of the terahertz beam to be changed, which can be accomplished by employing a bank of local oscillators (i.e., 202). For the pulsed operational mode, in particular, the range of the system 200 is governed by the following equation:
where:
-
- R is distance that can be measured or range;
- a is the radar cross section of the target (usually not equal to the physical cross section);
- S/N is single pulse SNR at the intermediate frequency IF filter output (envelope detector input);
- kTB is the effective incoming noise power in receiver bandwidth B (B≈1/pulsewidth);
- F is noise figure of the receiver (derived parameter);
- P is the peak transmitter power;
- G is the antenna power gain;
- λ is wavelength of the radiation (i.e., for 200 GHz, ≈1.5 mm);
- n is number of integrations of pulses in the receiver (multi-pulse averaging); and
- E(n) is the efficiency of integration.
For a monolithically integrated, low power IC that includes system 200, this range is generally less than one meter.
Turning to
In
Looking to
Turning to
In
Turning now to
In
Turning to
In
Turning to
Because the data bandwidth of system 200 is very high (i.e., on the order of tens of gigahertz), it is generally impractical to employ an ADC that digitizes the signals receives through by the receiver circuitry 228. In
To accomplish this, there are several approaches that can be taken. In
Another arrangement can be seen in
The filter 1702 can be seen in greater detail in
Yet another approach can be seen in
Turning to
As stated above, for a monolithically integrated, low power IC that includes system 200, this range is generally less than one meter. Thus, it should be apparent that in the terahertz frequency range, there is a shortage of available power, which results in decreased sensitivity, and with other frequency range systems being available that have fewer limitations than terahertz systems, transmission and reception in the terahertz range usually becomes attractive when there is a large increase in available bandwidth. However, transmitting, receiving, and digitizing such large bandwidths (i.e., >10 GHz) can be problematic due at least in part on analog-to-digital converter (ADC) performance requirements.
These issues, though, are addressed in system 200. In particular, system 200 generally employs an increased pulse repetition frequency (PRF) of the terahertz radar so as to reduce coherency losses due to target motion. By making use of a high PRF, a small portion (subset) of the total available time for reception can be digitized, and by scanning this subset rapidly, it is possible to generate the full reception interval, reducing the overhead for a very high sampling frequency on the ADC. The high PRF can also generally ensure that it is possible to digitize the desired reception interval very quickly. Additionally, because of the lack of signal power, most signals should include baseband averaging of pulse reception, in system 200 some averaging is performed in the analog domain so as to reduce the ADC and digitization conversion rate to be equal to the PRF, which is an easily manageable task.
Turning to
In operation, a digital output signal RXDATA and clock signal ADCCLKOUT are generated from the baseband input signals BBI and BBQ and DLL clock signal RXDLL. Typically, BBI and BBQ are differential signal (as shown), but may also be single-ended. These I and Q baseband signals BBI and BBQ (which are generally received from the summing circuitry 210) are respectively amplified by amplifiers 3002-1 and 3002-2. Because there are difficulties in digitizing the high bandwidth (as explained above), the performance requirements for ADCs 3008-1 and 3008-2 can be reduced by averaging the output of LNAs 3002-1 and 3002-1 with averagers 3004-1 and 3004-2.
The averagers 3008-1 and 3008-2 (which can be seen in greater detail in
Turning to
In
During digitization window 6006, averaging of the baseband signals BBI and BBQ is performed. The branch sample signals SAMPLE1 to SAMPLE16 (for the example of
Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.
Claims
1. A method comprising:
- transmitting a pulse of terahertz radiation through a touch panel formed of a dielectric material such that the pulse generates a evanescent field in a region adjacent to a touch surface of the touch panel;
- generating a reflected pulse from an object located within the region adjacent to the touch surface of the touch panel; and
- triangulating a position of the object on the touch surface of the touch panel at least in part from the reflected pulse.
2. The method of claim 1, wherein the step of triangulating further comprises:
- receiving the reflected pulse by a first receiver and a second receiver that are separated from one another by a distance; and
- calculating the position of the object based at least in part on a first elapsed time between transmission and reception at the first receiver, a second elapsed time between transmission and reception at the second receiver, and the distance.
3. The method of claim 1, wherein the reflected pulse further comprises a first reflected pulse, and wherein the step of triangulating further comprises:
- generating a second reflected pulse from a reflector included in the touch panel;
- receiving the first and second reflected pulses by a receiver; and
- calculating the position of the objected from the first and second reflected pulses.
4. The method of claim 3, wherein the reflector is located along the periphery of the touch panel.
5. The method of claim 1, wherein the pulse further comprises a first pulse, and wherein the reflected pulse further comprises a first reflected pulse, and wherein the first pulse is transmitted by a first transceiver, and wherein the method further comprises:
- transmitting a second pulse of terahertz radiation through a touch panel by a second transceiver; and
- generating a second reflected pulse from an object located within the region adjacent to the touch surface of the touch panel.
6. The method of claim 5, wherein the step of triangulating further comprises triangulating the location of the object on the touch surface of the touch panel from the first and second reflected pulses.
7. An apparatus comprising:
- a touch panel formed of a dielectric material that is configured to carry terahertz radiation and having a touch surface; and
- a touch controller that is optically coupled to touch panel, wherein the touch controller is configured to transmit a pulse of terahertz radiation through the touch panel so as to generate a evanescent field in a region adjacent to the touch surface, and wherein the touch controller is configured to receive a reflected pulse that is generated by an object located within the region, and wherein the touch controller is configured to triangulate a position of the object on the touch surface at least in part from the reflected pulse.
8. The apparatus of claim 7, wherein the touch controller further comprises:
- a signaling circuit that is configured to generate and receive terahertz radiation; and
- a control circuit that is coupled to the signal circuit.
9. The apparatus of claim 8, wherein the signaling circuit further comprises:
- a transceiver;
- a local oscillator that is coupled to the transceiver; and
- a receiver circuitry that is coupled to the transceiver.
10. The apparatus of claim 9, wherein the receiver circuitry further comprises an analog baseband circuit that averages the combined signal for a plurality of sampling periods within a digitization window to generate a plurality of averaged signals and that converts the plurality of averaged signals to a digital signal.
11. The apparatus of claim 10, wherein the analog baseband circuit further comprises:
- a clock circuit;
- a low noise amplifier (LNA) that is coupled to the summing circuit;
- an averager that is coupled to the LNA and the clock circuit;
- an analog-to-digital converter (ADC) that is coupled to the LNA and the clock circuit; and
- an output circuit that is coupled to the ADC.
12. The apparatus of claim 11, wherein the transmitter further comprises:
- a transmitter that is coupled to the local oscillator; and
- a plurality of receivers that are spaced apart from one another and that are each coupled to the receiver circuitry.
13. The apparatus of claim 12, wherein the touch panel further comprises a reflector.
14. A method comprising:
- transmitting a pulse of terahertz radiation through a touch panel formed of a dielectric material such that the pulse generates a evanescent field in a region adjacent to a touch surface of the touch panel;
- generating a plurality of reflected pulses, wherein a first reflected pulse is generated by a object located within the region adjacent to the touch surface of the touch panel; and
- triangulating a position of the object on the touch surface of the touch panel at least in part from the plurality of reflected pulses.
15. The method of claim 14, wherein the object further comprises a first object, and wherein the position further comprises a first position, and wherein a second reflected pulse of the plurality of reflected pulses is generated by a object located within the region adjacent to the touch surface of the touch panel and at a second location.
16. The method of claim 15, wherein the step of triangulating further comprises:
- receiving the plurality of reflected pulses by a first receiver and a second receiver that are separated from one another by a distance; and
- calculating the position of the object based at least in part on the plurality of reflected pulses.
17. The method of claim 16, wherein a third reflected pulse of the plurality of reflected pulses is generated by a reflector.
18. The method of claim 17, wherein the reflector is located along the periphery of the touch panel.
Type: Application
Filed: Jun 10, 2011
Publication Date: Dec 13, 2012
Applicant: Texas Instruments Incorporated (Dallas, TX)
Inventors: Baher S. Haroun (Allen, TX), Marco Corsi (Allen, TX), Brian P. Ginsburg (Allen, TX), Vijay B. Rentala (Plano, TX), Srinath M. Ramaswamy (Murphy, TX), Eunyoung Seok (Plano, TX)
Application Number: 13/158,010
International Classification: G06F 3/042 (20060101);