U.S. patent application number 16/056180 was filed with the patent office on 2018-12-06 for channel scan architecture for multiple stimulus multi-touch sensor panels.
This patent application is currently assigned to Apple Inc.. The applicant listed for this patent is Apple Inc.. Invention is credited to Christoph H. KRAH, Minh-Dieu Thi VU, Thomas James WILSON.
Application Number | 20180348957 16/056180 |
Document ID | / |
Family ID | 41798843 |
Filed Date | 2018-12-06 |
United States Patent
Application |
20180348957 |
Kind Code |
A1 |
WILSON; Thomas James ; et
al. |
December 6, 2018 |
CHANNEL SCAN ARCHITECTURE FOR MULTIPLE STIMULUS MULTI-TOUCH SENSOR
PANELS
Abstract
A channel scan architecture for detecting touch events on a
touch sensor panel is disclosed. The channel scan architecture can
combine drive logic, sense channels and channel scan logic on a
single monolithic chip. The channel scan logic can be configured to
implement a sequence of scanning processes in a panel subsystem
without intervention from a panel processor. The channel scan
architecture can provide scan sequence control to enable the panel
processor to control the sequence in which individual scans are
implemented in the panel subsystem. Type of scans that can be
implemented in the panel subsystem can include a spectral analysis
scan, touch scan, phantom touch scan, ambient light level scan,
proximity scan and temperature scan.
Inventors: |
WILSON; Thomas James;
(Falmouth, ME) ; KRAH; Christoph H.; (Cupertino,
CA) ; VU; Minh-Dieu Thi; (Cupertino, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
|
|
Assignee: |
Apple Inc.
Cupertino
CA
|
Family ID: |
41798843 |
Appl. No.: |
16/056180 |
Filed: |
August 6, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15158461 |
May 18, 2016 |
10042476 |
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16056180 |
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12208315 |
Sep 10, 2008 |
9348451 |
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15158461 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 3/0418 20130101;
G06F 3/04166 20190501; G06F 3/0416 20130101 |
International
Class: |
G06F 3/041 20060101
G06F003/041 |
Claims
1. A computing device comprising: a touch sensor panel including a
plurality of touch sensors; and circuitry configured to perform a
plurality of different types of scans of the touch sensor panel in
a sequence set by a processor, without further intervention from
the processor, the plurality of different types of scans including
a touch scan to generate touch sense data indicative of an object
touching or in proximity to the touch sensor panel.
2. The computing device of claim 1, wherein the circuitry comprises
stimulation circuitry configured to stimulate the touch sensor
panel and sense channels configured to sense the touch sensor
panel.
3. The computing device of claim 1, wherein the touch scan to
generate touch sense data comprises a multi-stimulation touch scan
to generate the touch sense data, wherein the multi-stimulation
touch scan includes concurrently stimulating the touch sensor panel
with multiple stimulation frequencies or multiple stimulation
phases.
4. The computing device of claim 1, the plurality of different
types of scans further including a spectral analysis scan to
generate frequency selection data indicative of a clean frequency
for use in the touch scan.
5. The computing device of claim 4, wherein the spectral analysis
scan includes performing in-phase and quadrature demodulation of
different frequencies at one or more sense channels coupled to the
touch sensor panel.
6. The computing device of claim 1, the plurality of different
types of scans further including a no stimulation scan to generate
calibration data indicative of a baseline noise level associated
with one or more of the plurality of touch sensors of the touch
sensor panel.
7. The computing device of claim 1, the touch sensor panel further
including one or more light sensors; wherein the plurality of
different types of scans further includes an ambient light level
scan of the one or more light sensors to generate light sense data
indicative of an ambient light level at the touch sensor panel.
8. The computing device of claim 1, the touch sensor panel further
including one or more proximity sensors; wherein the plurality of
different types of scans further includes a scan of the one or more
proximity sensors to generate proximity sense data indicative of
the object in proximity to the touch sensor panel.
9. The computing device of claim 1, further including a temperature
sensor; wherein the plurality of different types of scans further
includes a scan of the temperature sensor to generate temperature
data indicative of temperature-related drift.
10. The computing device of claim 1, wherein the touch scan is last
of the plurality of different types of scans in the sequence set by
the processor.
11. A method comprising: receiving a scanning sequence from a
processor; and performing, by circuitry independent from the
processor, a plurality of different types of scans of a touch
sensor panel according to the scanning sequence without further
intervention from the processor, the plurality of different types
of scans including a touch scan to generate touch sense data
indicative of an object touching or in proximity to the touch
sensor panel.
12. The method of claim 11, wherein the touch scan to generate
touch sense data comprises a multi-stimulation touch scan to
generate the touch sense data, wherein the multi-stimulation touch
scan includes concurrently stimulating the touch sensor panel with
multiple stimulation frequencies or multiple stimulation
phases.
13. The method of claim 11, wherein the plurality of different
types of scans further including a spectral analysis scan to
generate frequency selection data indicative of a clean frequency
for use in the touch scan.
14. The method of claim 13, wherein the spectral analysis scan
includes performing in-phase and quadrature demodulation of
different frequencies at one or more sense channels coupled to the
touch sensor panel.
15. The method of claim 11, the plurality of different types of
scans further including a no stimulation scan to generate
calibration data indicative of a baseline noise level associated
with one or more touch sensors of the touch sensor panel.
16. The method of claim 11, the plurality of different types of
scans further including an ambient light level scan of one or more
light sensors to generate light sense data indicative of an ambient
light level at the touch sensor panel.
17. The method of claim 11, the plurality of different types of
scans further including a scan of one or more proximity sensors to
generate proximity sense data indicative of the object in proximity
to the touch sensor panel.
18. The method of claim 11, wherein the plurality of different
types of scans further including a scan of a temperature sensor to
generate temperature data indicative of temperature-related
drift.
19. The method of claim 11, wherein the touch scan is last of the
plurality of different types of scans in the sequence from the
processor.
20. The method of claim 11, wherein the plurality of different
types of scans comprises a spectral analysis scan, a proximity scan
and a multi-stimulation touch scan, wherein the multi-stimulation
touch scan is performed when results of the proximity scan indicate
an object within a threshold distance of the touch sensor panel,
wherein the multi-stimulation touch scan is performed at a
frequency determined from results of the spectral analysis scan.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/158,461 (now U.S. Publication No.
2016-0266718), filed May 18, 2016, and is a continuation of U.S.
patent application Ser. No. 12/208,315 (now U.S. Pat. No.
9,348,451), filed Sep. 10, 2008, the entire disclosure of which is
incorporated herein by reference for all purposes.
FIELD OF THE INVENTION
[0002] This relates to touch sensor panels that utilize multiple
concurrent stimulation signals to detect and localize touch events,
and more particularly, to a cost and power effective channel scan
architecture capable of implementing a sequence of scans without
intervention from a panel processor.
BACKGROUND OF THE INVENTION
[0003] Many types of input devices are presently available for
performing operations in a computing system, such as buttons or
keys, mice, trackballs, touch sensor panels, joysticks, touch
screens and the like. Touch screens, in particular, are becoming
increasingly popular because of their ease and versatility of
operation as well as their declining price. Touch screens can
include a touch sensor panel, which can be a clear panel with a
touch-sensitive surface, and a display device that can be
positioned behind the panel so that the touch-sensitive surface can
substantially cover the viewable area of the display device. Touch
screens can allow a user to perform various functions by touching
the touch sensor panel using a finger, stylus or other object at a
location dictated by a user interface (UI) being displayed by the
display device. In general, touch screens can recognize a touch
event and the position of the touch event on the touch sensor
panel, and the computing system can then interpret the touch event
in accordance with the display appearing at the time of the touch
event, and thereafter can perform one or more actions based on the
touch event.
[0004] Touch sensor panels can be formed from a matrix of drive and
sense lines, with sensors or pixels defined, in some embodiments,
by where the drive and sense lines cross over or come close to each
other while being separated by a dielectric material. Drive or
transmitting logic can be coupled to the drive lines, and sense or
receiving channels can be coupled to the sense lines. During a
scanning process, the drive logic can drive each drive line with a
stimulation signal, and the sense channels can generate sense data
indicative of the amount of charge injected into the sense lines
due to the stimulation signal. A panel processor can identify touch
locations based on the sense data, because the amount of charge is
related to the amount of touch.
[0005] However, the voltage required by the drive logic for
providing the stimulation signal can be much higher than the
voltage required by the sense channels for sensing the injected
charge. This can force the drive logic and sense channels to be
implemented in discrete chips, causing the sensor panel circuitry
to be larger in size and more expensive.
[0006] Further, involvement by the panel processor in the scanning
process can occupy a significant amount of time, increasing the
processing burden of the panel processor beyond that which is
necessary to identify an occurrence or absence of a touch event
based on sense data generated from the scanning process. This
significant amount of processing time can make a processor too busy
to perform other functions and can slow down devices using a sensor
panel. Additionally, processors typically consume a significant
amount of power during operation, which can be particularly
problematic when a sensor panel is used in conjunction with a hand
held device, as many hand-held devices have a limited power
supply.
SUMMARY OF THE INVENTION
[0007] A channel scan architecture for detecting touch events on a
touch sensor panel is disclosed. The channel scan architecture can
combine drive logic, sense channels and channel scan logic on a
single monolithic chip. The channel scan logic can be configured to
implement a sequence of scanning processes in a panel subsystem
without intervention from a panel processor.
[0008] Providing sensor panel circuitry on a single chip achieves
hardware cost savings over multiple chip circuitry. The use of
multiple stimulation frequencies and phases to sense touch events
enables higher-power drive logic to operate with a reduced voltage
on the same chip as lower-power sense channels. Implementing touch
scanning functionality in dedicated logic in the panel subsystem
decreases the processing burden of the panel processor.
[0009] The channel scan architecture can provide scan sequence
control to enable the panel processor to control the sequence in
which individual scans are implemented in the panel subsystem. Type
of scans that can be implemented in the panel subsystem can
include, for example, a spectral analysis scan, touch scan, phantom
touch scan, ambient light level scan, proximity scan and
temperature scan.
[0010] The spectral analysis scan can be used to select a clean
frequency for use in the scan of the touch sensors. The touch scan
can be used to identify an occurrence or absence of a touch event
at the sensor panel. The phantom touch scan can be used to generate
calibration data to adjust a baseline noise level associated with
the touch sensors. The ambient light level scan can be used to
identify an ambient light level at the sensor panel. The proximity
scan can be used to identify an occurrence or absence of a
proximity event at the sensor panel, such as an object hovering
over the sensor panel. The temperature scan can be used to adjust
parameters, such as channel gains, delays and the touch data
baseline for example, to compensate for temperature-related drift
of such parameters.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates an exemplary computing system that can
use multiple stimulation frequencies and phases to sense touch
events with a channel scan architecture according to embodiments of
the invention.
[0012] FIG. 2A illustrates an exemplary circuit for generating
stimulation frequencies for stimulating the drive lines on the
touch sensor panel according to one embodiment of this
invention.
[0013] FIG. 2B illustrates another exemplary circuit for generating
stimulation frequencies for stimulating the drive lines on the
touch sensor panel according to one embodiment of this
invention.
[0014] FIG. 2C illustrates another exemplary circuit for generating
stimulation frequencies for stimulating the drive lines on the
touch sensor panel according to one embodiment of this
invention.
[0015] FIG. 3A illustrates a simplified block diagram of N
exemplary sense channel or event detection and demodulation
circuits according to one embodiment of this invention.
[0016] FIG. 3B illustrates another simplified block diagram of N
exemplary sense channel or event detection and demodulation
circuits according to one embodiment of this invention.
[0017] FIG. 4 illustrates an exemplary channel scan architecture
according to one embodiment of this invention.
[0018] FIG. 5 illustrates an exemplary flow diagram that can be
performed by logic associated with a panel subsystem according to
one embodiment of this invention.
[0019] FIG. 6 illustrates an exemplary flow diagram that can be
performed by logic associated with a spectral analysis scan
according to one embodiment of this invention.
[0020] FIG. 7 illustrates an exemplary flow diagram that can be
performed by logic associated with a touch scan according to one
embodiment of this invention.
[0021] FIG. 8 illustrates an exemplary flow diagram that can be
performed by logic associated with a phantom touch scan according
to one embodiment of this invention.
[0022] FIG. 9 illustrates an exemplary flow diagram that can be
performed by logic associated with an ambient light level scan
according to one embodiment of this invention.
[0023] FIG. 10 illustrates an exemplary flow diagram that can be
performed by logic associated with a proximity scan according to
one embodiment of this invention.
[0024] FIG. 11 illustrates an exemplary flow diagram that can be
performed by logic associated with a temperature scan according to
one embodiment of this invention.
[0025] FIG. 12A illustrates an exemplary mobile telephone
associated with a channel scan architecture according to one
embodiment of this invention.
[0026] FIG. 12B illustrates an exemplary media player associated
with a channel scan architecture according to one embodiment of
this invention.
[0027] FIG. 12C illustrates an exemplary personal computer
associated with a channel scan architecture according to one
embodiment of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] In the following description of preferred embodiments,
reference is made to the accompanying drawings where it is shown by
way of illustration specific embodiments in which the invention can
be practiced. It is to be understood that other embodiments can be
used and structural changes can be made without departing from the
scope of the embodiments of this invention.
[0029] This relates to providing a cost and power effective
architecture for detecting touch events on a touch sensor panel. In
particular, drive logic, sense channels and channel scan logic can
be provided on a single monolithic chip. Providing sensor panel
circuitry on a single chip achieves hardware cost savings over
multiple chip circuitry. The use of multiple stimulation
frequencies and phases to sense touch events enables higher-power
drive logic to operate with a reduced voltage on the same chip as
lower-power sense channels. Further, channel scan logic can be
provided to implement a sequence of scanning processes without
intervention from a panel processor. Implementing touch scanning
functionality in dedicated logic decreases the processing burden of
the panel processor.
[0030] Although some embodiments of this invention may be described
herein in terms of mutual capacitance touch sensors, it should be
understood that embodiments of this invention are not so limited,
but are generally applicable to other types of touch sensors such
as self capacitance touch sensors. Furthermore, although the touch
sensors in the touch sensor panel may be described herein in terms
of an orthogonal array of touch sensors having drive and sense
lines arranged in rows and columns, it should be understood that
embodiments of this invention are not limited to row and columns or
orthogonal arrays, but can be generally applicable to touch sensors
arranged in any number of dimensions and orientations, including
diagonal, concentric circle, and three-dimensional and random
orientations. In addition, the touch sensor panel described herein
can be either a single-touch or a multi-touch sensor panel, the
latter of which is described in Applicant's co-pending U.S.
application Ser. No. 11/649,998 entitled "Proximity and Multi-Touch
Sensor Detection and Demodulation," filed on Jan. 3, 2007, the
contents of which are incorporated by reference herein in their
entirety for all purposes. The touch sensor panel may have drive
and sense lines formed on separate substrates, opposite sides of a
single substrate, or on the same side of a single substrate, some
embodiments of the latter being described in U.S. patent
application Ser. No. 12/110,075, entitled "Brick Layout and Stackup
for a Touch Screen," filed on Apr. 25, 2008, the contents of which
are incorporated herein by reference in their entirety for all
purposes.
[0031] FIG. 1 illustrates exemplary computing system 100 that can
use multiple stimulation frequencies and phases to sense touch
events with a channel scan architecture according to embodiments of
the invention. Computing system 100 can include one or more panel
processors 102 and peripherals 104, and panel subsystem 106. One or
more panel processors 102 can include, for example, ARM968
processors or other processors with similar functionality and
capabilities. However, in other embodiments, the panel processor
functionality can be implemented instead by dedicated logic, such
as a state machine. Peripherals 104 can include, but are not
limited to, random access memory (RAM) or other types of memory or
storage, watchdog timers and the like. Panel subsystem 106 can
include, but is not limited to, one or more sense channels 108,
channel scan logic 110 and driver logic 114. Channel scan logic 110
can access RAM 112, autonomously read data from the sense channels
and provide control for the sense channels. In addition, channel
scan logic 110 can control driver logic 114 to generate stimulation
signals 116 at various frequencies and phases that can be
selectively applied to multiple rows of touch sensor panel 124. In
some embodiments, panel subsystem 106, panel processor 102 and
peripherals 104 can be integrated into a single application
specific integrated circuit (ASIC).
[0032] Touch sensor panel 124 can include a capacitive sensing
medium having a plurality of row traces or driving lines and a
plurality of column traces or sensing lines, although other sensing
media can also be used. The drive and sense lines can be formed
from a transparent conductive medium such as Indium Tin Oxide (ITO)
or Antimony Tin Oxide (ATO), although other transparent and
non-transparent materials such as copper can also be used. In some
embodiments, the drive and sense lines can be perpendicular to each
other, although in other embodiments other non-Cartesian
orientations are possible. For example, in a polar coordinate
system, the sensing lines can be concentric circles and the driving
lines can be radially extending lines (or vice versa). It should be
understood, therefore, that the terms "drive line" and "sense
line," "row" and "column," "first dimension" and "second
dimension," or "first axis" and "second axis" as used herein are
intended to encompass not only orthogonal grids, but the
intersecting traces or adjacent patterns of other geometric
configurations having first and second dimensions (e.g. the
concentric and radial lines of a polar-coordinate arrangement).
[0033] Where the drive and sense lines pass above and below (cross)
each other (but do not make direct electrical contact with each
other), or are adjacent to or nearby each other (in the case of
drive and sense lines formed on the same side of a single
substrate), the drive and sense lines can essentially form pairs of
electrodes. Each pair of electrodes can represent a capacitive
sensing node and can be viewed as picture element (pixel) 126,
which can be particularly useful when touch sensor panel 124 is
viewed as capturing an "image" of touch. (In other words, after
processor 102 has determined whether a touch event has been
detected at each touch sensor in the touch sensor panel, the
pattern of touch sensors in the multi-touch panel at which a touch
event occurred can be viewed as an "image" of touch (e.g., a
pattern of fingers touching the panel). The capacitance between the
pixel electrodes appears as a stray capacitance when the drive line
for that pixel is held at direct current (DC) voltage levels and as
a mutual signal capacitance Csig when the drive line is stimulated
with an alternating current (AC) signal. The presence of a finger
or other object near or on the touch sensor panel can be detected
by measuring changes to a signal charge Qsig present at the pixels
being touched, which is a function of Csig. Each sense line of
touch sensor panel 124 can drive sense channel 108 (also referred
to herein as an event detection and demodulation circuit) in panel
subsystem 106.
[0034] Computing system 100 can also include host processor 128 for
receiving outputs from panel processor 102 and performing actions
based on the outputs that can include, but are not limited to,
moving an object such as a cursor or pointer, scrolling or panning,
adjusting control settings, opening a file or document, viewing a
menu, making a selection, executing instructions, operating a
peripheral device connected to the host device, answering a
telephone call, placing a telephone call, terminating a telephone
call, changing the volume or audio settings, storing information
related to telephone communications such as addresses, frequently
dialed numbers, received calls, missed calls, logging onto a
computer or a computer network, permitting authorized individuals
access to restricted areas of the computer or computer network,
loading a user profile associated with a user's preferred
arrangement of the computer desktop, permitting access to web
content, launching a particular program, encrypting or decoding a
message, and/or the like. Host processor 128 can also perform
additional functions that may not be related to panel processing,
and can be coupled to program storage 132 and display device 130
such as an LCD display for providing a UI to a user of the
device.
[0035] In some systems, sensor panel 124 can be driven by
high-voltage driver logic. The high voltages that can be required
by the high-voltage driver logic (e.g. 18V) can force the
high-voltage driver logic to be formed separate from panel
subsystem 106, which can operate at much lower digital logic
voltage levels (e.g. 1.7 to 3.3V). However, in embodiments of the
invention, on-chip driver logic 114 can replace the off-chip high
voltage driver logic. Although panel subsystem 106 can have low,
digital logic level supply voltages, analog or digital panel driver
circuitry may be implemented on chip. In one embodiment, panel
driver circuitry 114 can generate stimulus voltage levels up to
twice the maximum voltage allowable for the process of the
multi-touch ASIC (e.g. 1.7 to 3.3V) by cascoding two transistors.
The high voltage supply can be furnished by charge pump 115 that
can also be integrated into the multi-touch ASIC. Although FIG. 1
shows charge pump 115 separate from driver logic 114, the charge
pump can be part of the driver logic.
[0036] FIG. 2A illustrates one exemplary circuit 200 for generating
stimulation frequencies for stimulating drive lines on a touch
sensor panel according to embodiments of the invention. In FIG. 2A,
more than one numerically controlled oscillator (NCO) 202 (e.g.
NCOA, NCOB, NCOC), each generating a signed M-bit digital
representation of a different frequency, can be summed in summing
circuit 204, producing composite digital waveform 206, which can be
converted into an analog waveform by DAC 214. DAC 214 can generate
two phases of the analog waveform, a non-inverted (0 degrees or
positive phase) version 216 (referred to as VSTM_P), and an
inverted (180 degrees or negative phase) version 218 (referred to
as VSTM_N) of the analog waveform. VSTM_N, VSTM_P, a common mode
voltage VSTM_CM 220 and 0V (see 222) are fed into switch matrix
224. Following the switch matrix is an array of output buffers 226,
one per panel drive line. Control signal OBIN_SEL[ ] 228 allows
independent selection of either VSTM_P, VSTM_N, VSTM_CM or 0V for
each of the output buffers.
[0037] FIG. 2B illustrates another exemplary circuit 208 for
generating stimulation frequencies for stimulating drive lines on a
touch sensor panel according to embodiments of the invention. In
FIG. 2B, more than one NCO 202 are each fed into one or more DACs
210, producing separate analog waveforms 212 VSTM_P_A 230, VSTM_N_A
232, VSTM_P_B 234, VSTM_N_B 236, VSTM_P_C 238, and VSTM_N_C 240,
which are fed into switch matrix 224 along with common mode voltage
VSTM_CM 220 and 0V 222. Following switch matrix 224 is an array of
output buffers 226, one per panel drive line. Control signal
OBIN_SEL[ ] 228 allows independent selection of either VSTM_P_A
230, VSTM_N_A 232, VSTM_P_B 234, VSTM_N_B 236, VSTM_P_C 238,
VSTM_N_C 240, VSTM_CM 220 or 0V (see 222) for each of the output
buffers.
[0038] FIG. 2C illustrates exemplary circuit 208 according to an
embodiment of the invention in which only one NCO 202 is fed into
DAC 210, producing separate analog waveforms 212 VSTM_P 230 and
VSTM_N 232, which are fed into switch matrix 224 along with common
mode voltage VSTM_CM 220 and 0V 222. In the embodiment illustrated
in FIG. 2C, control signal OBIN_SEL[ ] 228 allows independent
selection of either VSTM_P 230, VSTM_N 232, VSTM_CM 220 or 0V (see
222) for each of the output buffers. Note that in either of FIG.
2A, 2B or 2C, a composite waveform will be seen on the sense lines
of the touch sensor panel.
[0039] FIG. 3A illustrates a simplified block diagram of N
exemplary sense channel or event detection and demodulation
circuits 300 according to an embodiment of the invention. Each
charge amplifier or programmable gain amplifier (PGA) 302 in sense
channel 300 can be connected to analog front end channel 309, which
in turn can be connected to R signal mixers 304. Beside PGA 302,
analog front end channel 309 can include anti-aliasing filter 301,
ADC 303, and result register 305. Each signal mixer 304 multiplies
the digital signal from analog front end channels 309 with a
demodulation signal generated by NCO 315 at the same stimulation
frequencies generated by the circuits of FIGS. 2A and 2B. The
demodulated output of each signal mixer 304 can be connected to a
separate accumulator 308 and results register 307. FIG. 3B
illustrates a simplified block diagram of N exemplary sense channel
or event detection and demodulation circuits 300 according to an
embodiment of the invention in which only a single demodulator is
used per channel.
[0040] A more detailed description of an exemplary touch sensor
panel and associated sense circuitry for using multiple stimulation
frequencies and phases to detect touch events is described in U.S.
application Ser. No. 11/818,345 filed on Jun. 13, 2007 and entitled
"Multiple Simultaneous Frequency Detection," the contents of which
are incorporated by reference herein in their entirety for all
purposes.
[0041] A touch scan can be performed to capture multi-touch sense
data without intervention from the panel processor, so that the
sense data can be available for processing by the processor after a
touch event has occurred. This can aid in the conservation of power
as it does not require intervention from the panel processor during
the scan. In the touch scan, composite multi-touch data can be
captured over multiple timing sequences (e.g, 16 sequences, 200 us
each) and posted into a buffer. Since this multi-touch data is
composite data, a separate matrix decode logic can be utilized to
extract the actual per-pixel Csig values and post them to memory,
such as SRAM, where the processor can access the data for further
processing after a touch event has occurred. Each touch scan can
include several individual image scans, each performed at one or
multiple different stimulus frequencies. The touch scan can precede
or follow a scan in an auto-scan mode or can be performed in a
separate scan.
[0042] A more detailed description of an auto-scan mode is
described in U.S. application Ser. No. 12/022,572 filed on Jan. 30,
2008 and entitled "Auto Scanning for Multiple Frequency Stimulation
Multi-Touch Sensor Panels," the contents of which are incorporated
by reference herein in their entirety for all purposes.
[0043] FIG. 4 illustrates exemplary channel scan architecture 400
according to one embodiment of this invention. In this
architecture, processor 102 provides control to panel scan logic
408 to implement a sequence of scanning processes using components
of subsystem 106, including sense channels 414, drive channels 426,
and auxiliary channels and demodulators 410. Auxiliary channels and
demodulators 410 pertain to sensing circuitry associated with
sensors other than touch sensors, such as, for example, light,
proximity and temperature sensors. Configuration registers 428 can
store configuration data (counter values, phase increments, etc.)
utilized by panel scan logic 408 in controlling each component of
subsystem 106. Stimulation matrix 418 can determine the stimulation
signals to be provided by drive channels 426, and matrix decode
logic 420, result RAM 422 and matrix decode RAM 424 can be used to
extract the per-pixel Csig values on the sense side. Panel scan
logic 408 can be clocked by high frequency oscillator (HFO) 406 or
low frequency oscillator (LFO) 402. HFO 406 and LFO 402 can be
managed by clock and power manager 404, which can enable or disable
the oscillators depending on whether a scan occurs in an active
mode or auto-scan mode for example.
[0044] FIG. 5 illustrates an exemplary flow diagram that can be
performed by dedicated logic associated with panel subsystem 106
according to one embodiment of this invention. Each of the
described scans can be implemented by panel scan logic 408 of FIG.
4 in a particular sequence without intervention from panel
processor 102. For example, during a particular scan sequence,
subsystem 106 can perform a spectral analysis scan (step 500)
followed by a touch scan (505). Depending on whether they are
enabled (steps 510, 520, 530, 540), subsystem 106 can perform a
phantom scan (step 515), ambient light level scan (step 525),
proximity scan (535) and a temperature scan (step 545). FIGS. 6-11
describe particular operations that can be associated with each
scan in an active mode, in which processor 102 is active to receive
an interrupt from subsystem 106 after each scan is implemented.
[0045] FIG. 6 illustrates an exemplary flow diagram that can be
performed by logic associated with the spectral analysis scan
according to one embodiment of this invention. The spectral
analysis scan can be used to select a clean frequency for use in
the scan of the touch sensors. In particular, subsystem 106 can
configure the system for the spectral analysis scan (step 600),
which can entail adjusting gains and delays of the appropriate
circuitry. With the touch sensor drive channels disabled (e.g.,
driver logic 114 in FIG. 1 disabled so that no stimulation signals
are sent to any of the drive lines in touch sensor panel 124),
subsystem 106 can perform in-phase and quadrature demodulation, for
different frequencies, of the sum of all analog output data at the
touch sensor sense channels (step 610) for a number of sample
clocks (e.g., mixers 304 and NCOs 315 in each sense channel 300 in
FIG. 3 can perform in-phase and quadrature demodulation at
different frequencies). When complete, the demodulated data can be
posted to result registers (620) (e.g., result RAM 422 in FIG. 4),
and an interrupt can be generated to the panel processor (630)
notifying the processor that the spectral analysis scan is
complete. At this stage, the processor can process the result data
to select a clean frequency for use in the subsequent touch scan
operation. A more detailed description of a spectral analysis scan
is described in U.S. application Ser. No. 11/818,454 entitled
"Detection of Low Noise Frequencies for Multiple Frequency Sensor
Panel Stimulation," filed on Jun. 13, 2007, the contents of which
are incorporated by reference herein in their entirety for all
purposes.
[0046] FIG. 7 illustrates an exemplary flow diagram that can be
performed by logic associated with the touch scan according to one
embodiment of this invention. The touch scan can be used to
identify an occurrence or absence of a touch event at the sensor
panel. In particular, subsystem 106 can configure the system for
the touch scan (step 700), which can entail adjusting gains and
delays of the appropriate circuitry. With the touch sensor drive
channels enabled (e.g., driver logic enabled so that stimulation
signals are sent to the drive lines in touch sensor panel as
specified by the stimulation matrix RAM 418 of FIG. 4), subsystem
106 can concurrently stimulate the touch sensors with different
stimulation signals (step 710) for a number of sample clocks. When
complete, the demodulated data can be posted to result registers
(720). Since the demodulated data represents composite sense data,
subsystem 106 can decode the composite touch data into
sensor-specific touch data (i.e., the per-pixel Csig values) using
the matrix decode finite state machine 420 in FIG. 4, and post the
decoded data into the result registers (step 740). Steps 710-740
can be repeated for multiple timing sequences using the stimulation
signals identified in the stimulation matrix. When complete, an
interrupt can be generated to the panel processor (750) notifying
the processor that the touch scan is complete.
[0047] FIG. 8 illustrates an exemplary flow diagram that can be
performed by logic associated with the phantom touch scan according
to one embodiment of this invention. The phantom touch scan can be
used to generate calibration data to adjust a baseline noise level
associated with the touch sensors. In particular, subsystem 106 can
configure the system for the phantom touch scan (step 800), which
can entail adjusting gains and delays of the appropriate circuitry.
With the touch sensor drive channels disabled, subsystem 106 can
perform a touch scan demodulation at the touch sensor sense
channels (step 810) for a number of sample clocks at a particular
frequency (e.g., a mixer 304 and NCO 315 in each sense channel 300
in FIG. 3 can demodulate the no-stimulation sense outputs of the
touch sensor panel). When complete, the demodulated data can be
posted to result registers (820), and an interrupt can be generated
to the panel processor (830) notifying the processor that the
phantom touch scan is complete. A more detailed description of
phantom scanning and calibration is described in U.S. application
Ser. No. 11/650,204 entitled "Error Compensation for Multi-Touch
Surfaces," filed on Jan. 3, 2007, the contents of which are
incorporated herein by reference in their entirety for all
purposes.
[0048] FIG. 9 illustrates an exemplary flow diagram that can be
performed by logic associated with an ambient light level scan
according to one embodiment of this invention. The ambient light
level scan can utilize one or more ambient light sensors
incorporated into the sensor panel, and can be used to identify an
ambient light level at the sensor panel. In particular, subsystem
106 (or alternatively, host processor 128 in FIG. 1), can configure
the system for the ambient light level scan (step 900), which can
entail adjusting gains and delays of the appropriate circuitry.
Subsystem 106 (or the host processor) can capture light sensor data
at light sensor sense channels (step 910) for a number of sample
clocks (e.g., an auxiliary sense channel 410 in FIG. 4 can detect
the ambient light level from a signal received from an ambient
light sensor). When complete, the captured data can be posted to
result registers (920), and an interrupt can be generated to the
panel processor (930) notifying the processor that the ambient
light level scan is complete. Alternatively, the ambient light
sensor can generate digital values that can be communicated over a
digital interface to the host processor, where similar processing
can be performed. A more detailed description of a sensor panel
including an ambient light sensor is described in U.S. application
Ser. No. 11/800,293 entitled "Luminescence Shock Avoidance in
Display Devices," filed on May 4, 2007, the contents of which are
incorporated by reference herein in their entirety for all
purposes.
[0049] FIG. 10 illustrates an exemplary flow diagram that can be
performed by logic associated with a proximity scan according to
one embodiment of this invention. The proximity scan can be used to
identify an occurrence or absence of a proximity event at the
sensor panel, such as an object hovering over the sensor panel. In
particular, subsystem 106 can configure the system for the
proximity scan (step 1000), which can entail adjusting gains and
delays of the appropriate circuitry. With the proximity sensor
drive channels enabled, subsystem 106 can stimulate the proximity
sensors (step 1010) for a number of sample clocks. When complete,
the demodulated data can be posted to result registers (1020), and
an interrupt can be generated to the panel processor (1030)
notifying the processor that the proximity scan is complete. A more
detailed description of proximity sensors is described in U.S.
application Ser. No. 11/818,345 entitled "Proximity and Multi-Touch
Sensor Detection and Demodulation," previously incorporated by
reference above.
[0050] FIG. 11 illustrates an exemplary flow diagram that can be
performed by logic associated with a temperature scan according to
one embodiment of this invention. The temperature scan can utilize
a temperature sensor incorporated into computing system 100, such
as in panel subsystem 106 for example. The temperature scan can be
used to adjust parameters, such as channel gains, delays and the
touch data baseline for example, to compensate for
temperature-related drift of such parameters. In particular,
subsystem 106 can configure the system for the temperature scan
(step 1100), which can entail adjusting gains and delays of the
appropriate circuitry. Subsystem 106 can capture temperature data
from the temperature sensor (step 1110) for a number of sample
clocks. When complete, the captured data can be posted to result
registers (1120), and an interrupt can be generated to the panel
processor (1130) notifying the processor that the temperature scan
is complete.
[0051] In another embodiment, the scanning operations described in
FIGS. 7-11 can be implemented in an auto-scan mode in which
processor 102 is inactive. In this embodiment, since processor 102
is in an inactive state, panel subsystem 10 can wait until after
all of the scans in a particular scan sequence have completed
before awakening processor 102, rather than generating an interrupt
to processor 102 after each scan as described above.
[0052] Panel scan logic 408 can include a scan sequence control
(e.g., as shown by "PSCN_CTRL" and "PSCN_CFG" in FIG. 4). The scan
sequence control can enable processor 102 to control the sequence
in which the individual scans are performed by panel subsystem 106.
For example, in certain applications, it may be beneficial to
perform the temperature scan prior to the touch scan to calibrate
out any temperature-related effects prior to touch scanning.
Similarly, it may be beneficial to perform the proximity scan prior
to the touch scan in certain applications, such as power sensitive
applications for example. For instance, it may be beneficial to
only perform the touch scan when an object is within a certain
proximity of the touch panel. In one embodiment, the proximity scan
can be used to detect if an object (such as a finger for example)
is close by, and if the object is within a certain distance to the
panel, then the touch scan is performed; otherwise the touch scan
can be skipped.
[0053] According to an embodiment of the invention, the scan
sequence control can be implemented as a scan sequence memory
(e.g., in configuration registers 428), with each memory location
(1 to N) indicating the order of scanning. For example, the memory
can be 5 memory locations deep, with each memory location
containing a 3 bit value that indicates the type of scan, as
illustrated by the following: [0054] 0=Touch scan [0055] 1=Phantom
touch scan [0056] 2=Ambient light level scan [0057] 3=Proximity
scan [0058] 4=Temperature scan
[0059] In this example, it can be presumed that the spectral
analysis scan will always be implemented first in a scan sequence.
According to the above example, the following exemplary scan
sequence memory configuration:
TABLE-US-00001 Memory Location Data 0 1 1 2 2 3 3 4 4 0
can represent the following scan sequence after completion of the
spectral analysis scan: phantom touch scan->ambient light level
scan->proximity scan->temperature scan->touch scan.
Processor 102 can set the scan sequence in configuration registers
428, allowing panel scan logic 408 to implement the scan sequence
based on the set data without intervention from processor 102.
[0060] FIG. 12A illustrates exemplary mobile telephone 1236 that
can include touch sensor panel 1224 and display device 1230, the
touch sensor panel associated with a channel scan architecture
according to embodiments of the invention.
[0061] FIG. 12B illustrates exemplary digital media player 1240
that can include touch sensor panel 1224 and display device 1230,
the touch sensor panel associated with a channel scan architecture
according to embodiments of the invention.
[0062] FIG. 12C illustrates exemplary personal computer 1244 that
can include touch sensor panel 1224 and display 1230, the touch
sensor panel and/or display of the personal computer (in
embodiments where the display is part of a touch screen) associated
with a channel scan architecture according to embodiments of the
invention. The mobile telephone, media player and personal computer
of FIGS. 12A, 12B and 12C can achieve improved touch panel
operation by utilizing a channel scan architecture according to
embodiments of the invention.
[0063] Although embodiments of this invention have been fully
described with reference to the accompanying drawings, it is to be
noted that various changes and modifications will become apparent
to those skilled in the art. Such changes and modifications are to
be understood as being included within the scope of embodiments of
this invention as defined by the appended claims.
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