U.S. patent application number 16/191248 was filed with the patent office on 2019-08-15 for touch sensitive apparatus with improved spatial resolution.
The applicant listed for this patent is FlatFrog Laboratories AB. Invention is credited to Mats Petter WALLANDER.
Application Number | 20190250769 16/191248 |
Document ID | / |
Family ID | 53179887 |
Filed Date | 2019-08-15 |
United States Patent
Application |
20190250769 |
Kind Code |
A1 |
WALLANDER; Mats Petter |
August 15, 2019 |
TOUCH SENSITIVE APPARATUS WITH IMPROVED SPATIAL RESOLUTION
Abstract
A touch-sensitive apparatus comprising a panel defining a touch
surface; a first set of opposite and essentially parallel rows of
components, and a second set of opposite and essentially parallel
rows of components. The second set of opposite and parallel rows
being essentially orthogonal to the first set of opposite and
parallel rows. The components include emitters and detectors, each
emitter being operable for propagating an energy beam across the
touch surface inside the panel, and each detector being operable
for detecting transmitted energy from at least one emitter. Two of
the rows of the first and second set are interleaved rows each
having an interleaved distribution of emitters and detectors, and
the further two rows of the first and second set are base rows each
having a distribution of components comprising at least 70%
emitters or detectors.
Inventors: |
WALLANDER; Mats Petter;
(Lund, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FlatFrog Laboratories AB |
Lund |
|
SE |
|
|
Family ID: |
53179887 |
Appl. No.: |
16/191248 |
Filed: |
November 14, 2018 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15103635 |
Jun 10, 2016 |
10152176 |
|
|
PCT/SE2014/051363 |
Nov 17, 2014 |
|
|
|
16191248 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 2203/04109
20130101; G06F 3/0421 20130101 |
International
Class: |
G06F 3/042 20060101
G06F003/042 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 22, 2013 |
SE |
1351390-8 |
Claims
1. A touch-sensitive apparatus, comprising: a panel (1) defining a
touch surface (4); and a first set of opposite and essentially
parallel rows (20A, 20B) of components (2, 3); a second set of
opposite and essentially parallel rows (22A, 22B) of components (2,
3), said second set of opposite and parallel rows (22A, 22B) being
essentially orthogonal to the first set of opposite and parallel
rows (20A, 20B), wherein the components include emitters (2) and
detectors (3), each emitter (2) being operable for propagating an
energy beam across the touch surface (4) inside the panel (1), and
each detector (3) being operable for detecting transmitted energy
from at least one emitter (2); characterized in that two of the
rows (20A, 20B, 22A, 22B) of the first and second set are
interleaved rows each having an interleaved distribution of
emitters (2) and detectors (3), and wherein the further two rows
(20A, 20B, 22A, 22B) of the first and second set are base rows each
having a distribution of components (2, 3) comprising at least 70%
emitters (2) or detectors (3).
2.-18. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of Swedish patent
application No. 1351390-8, filed on Nov. 22, 2013.
FIELD OF THE INVENTION
[0002] The present invention relates to a touch sensitive apparatus
that operates by propagating energy beams across a touch surface
inside a panel.
BACKGROUND OF THE INVENTION
[0003] This type of touch-sensitive apparatus is known in the art.
It may be implemented to operate by transmitting light inside a
solid light transmissive panel, which defines two parallel boundary
surfaces connected by a peripheral edge surface. Light generated by
a plurality of emitters is coupled into the panel so as to
propagate by total internal reflection (TIR) between the boundary
surfaces to a plurality of detectors. The light thereby defines
propagation paths across the panel, between pairs of emitters and
detectors. The emitters and detectors are arranged such that the
propagation paths define a grid on the panel. An object that
touches one of the boundary surfaces ("the touch surface") will
attenuate ("frustrate") the light on one or more propagation paths
and cause a change in the light received by one or more of the
detectors. The location (coordinates), shape or area of the object
may be determined by analyzing the received light at the detectors.
This type of apparatus has an ability to detect plural objects in
simultaneous contact with the touch surface, known as "multi-touch"
in the art.
[0004] In one configuration, e.g. disclosed in U.S. Pat. Nos.
3,673,327, 4,254,333 and US2006/0114237, the emitters and detectors
are arranged in rows on opposite ends of the panel, and the light
is propagated between opposite pairs of emitters and detectors so
as to define a rectangular grid of propagation paths.
[0005] As an alternative, U.S. Pat. No. 7,432,893 proposes the use
of a few large emitters arranged at the corners of the panel, or
centrally on each end of the panel, to inject diverging light beams
("fan beams") into the panel for receipt by arrays of detectors
along all ends of the panel. This configuration may enable an
increased spatial resolution for a given number of emitters and
detectors, by increasing the density of the grid of propagation
paths. The spatial resolution indicates the smallest object that
can be detected by the touch-sensitive apparatus at a given
location on the touch surface.
[0006] In an alternative configuration, e.g. disclosed in
WO2009/077962, US2011/0234537, US2011/0157096, rows of regularly
spaced fan beam emitters and detectors, respectively, are arranged
on opposite ends of the panel to define a dense grid of propagation
paths across the touch surface.
[0007] WO2010/064983 discloses further alternative configurations.
In one configuration, which is intended to improve the uniformity
of the grid of propagation paths, fan beam emitters and detectors
are alternated with equal spacing around the periphery of the touch
surface. In another configuration, which is intended to reduce
interference phenomena that may occur when different emitters
concurrently inject light of the same wavelength into the panel,
fan beam emitters and detectors are arranged with randomized
spacing around the periphery of the touch surface.
[0008] In this type of touch-sensitive apparatus, there is a
continued desire to improve the spatial resolution with respect to
the uniformity of the spatial resolution across the touch surface
or the minimum detectable object size at a given position on the
touch surface.
[0009] The touch-sensitive technology is further incorporated into
consumer products which face challenges such as cost reduction to
be competitive products. There is thus desire to reduce cost
without endangering the user experience. The components of the
touch-sensitive apparatus might also be exposed to disturbances
such as ambient noise and noise from the apparatus itself. It is an
ongoing desire to reduce the impact of disturbances to the
components.
SUMMARY OF THE INVENTION
[0010] Tl is an objective of the invention to at least partly
overcome one or more limitations of the prior art.
[0011] Another objective is to enable an improved spatial
resolution for a given number of electro-optical components in a
touch-sensitive apparatus that operates by propagating energy beams
across a touch surface inside a panel.
[0012] A further objective is to provide an apparatus at a reduced
cost without influencing the user experience.
[0013] A still further objective is to provide an apparatus that is
less sensitive to disturbances than some prior apparatuses.
[0014] One or more of these objectives, as well as further
objectives that may appear from the description below, are at least
partly achieved by means of a touch-sensitive apparatus according
to the independent claim, embodiments thereof being defined by the
dependent claims.
[0015] One aspect of the invention is a touch-sensitive apparatus
which comprises a panel defining a touch surface; a first set of
opposite and essentially parallel rows of components, and a second
set of opposite and essentially parallel rows of components.
[0016] The second set of opposite and parallel rows is essentially
orthogonal to the first set of opposite and parallel rows. The
components include emitters and detectors, each emitter being
operable for propagating an energy beam across the touch surface
inside the panel, and each detector being operable for detecting
transmitted energy from at least one emitter, Two of the rows of
the first and second set are interleaved rows each having an
interleaved distribution of emitters and detectors, and the further
two rows of the first and second set are base rows each having a
distribution of components comprising at least 70% emitters or
detectors.
[0017] This aspect is based on the insight that the configurations
of prior art solutions, which propagate diverging energy beams
inside a panel and have alternating components of emitters and
detectors in opposite rows, will result in a convergence of the
propagation paths, typically towards the center line between the
opposite rows. Thereby, the grid of propagation paths will exhibit
increased spatial gaps without propagation paths, or angular gaps
without propagation paths in large angular intervals, which is
equal to a locally reduced spatial resolution and/or accuracy. A
spatial gap is an area between propagation paths exhibiting no
propagation paths. Also, prior art solutions having an "L-shaped"
distribution of components such that two adjacent orthogonal rows
comprise the same type of component will result in gaps without
propagation paths or without propagation paths in large angular
intervals. To overcome these drawbacks, the first aspect applies
the design rule that the apparatus comprises four rows of
components, wherein two rows arc interleaved rows and the other two
rows each has a distribution of components comprising at least 70%
emitters or detectors. By applying this design rule, the number of
propagation paths with different angles may be increased and the
propagation paths may be more evenly distributed over the touch
surface. By proper choice and arrangement of components, the first
aspect thus provides an improved distribution of detection lines
with different angles over the touch surface for a given number of
components, compared to conventional arrangements of components.
Thus, the spatial resolution and/or accuracy of the touch surface
can be increased, or, the spatial resolution and/or accuracy can be
essentially maintained with a reduced number of components. A
reduced number of components might imply a reduced cost for the
apparatus.
[0018] A detection line can be defined by a distance from a centre
point of the touch surface, and an angle from e.g. a horizontal
line through the centre point. To obtain a certain spatial
resolution and accuracy, it is desired that each point on the touch
surface shall have a certain number of detection lines within a
distance to the point, and with a distribution of angles for the
detection lines. According to one embodiment, each point on the
touch surface shall have detection lines with an angle of less than
20.degree., preferably less than 10.degree., in between the angles
between detection lines within a distance to the point. The
distance may e.g. be an approximated radius of a fingerpalm.
[0019] The components may be arranged in connection with one or
several printed circuit boards (PCBs), and connected to a plurality
of distributed processors on the PCBs. For example, a certain
number of components may be connected to the same processor. It may
be desired to connect only one type of component to the same
processor, as it may be an easier implemented solution. For
example, signals from the same component type should be treated in
the same way by the processor. Further, by having separate
processors for different component types, the influence of the
emitters to the detectors may be reduced. Base rows with at least
70% of one type of component might thus be easier to implement than
rows with a more even distribution of components.
[0020] According to one embodiment, the interleaved rows constitute
the first set of opposite and parallel rows.
[0021] According to another embodiment, the interleaved rows
constitute one row of the first set of opposite and parallel rows,
and one row of the second set of opposite and parallel rows.
[0022] According to one embodiment, the base rows comprises one row
with X numbers of emitters and one row with Y numbers of detectors,
wherein X is different from Y. Thus, the number of emitters in one
base row may be greater than the number of detectors in the other
base row. Or, the number of emitters in the one base row may be
less than the number of detectors in the other base row.
[0023] According to one embodiment, one of the base rows has a
distribution of components comprising at least 70% emitters and the
other base row has a distribution of components comprising at least
70% detectors. Thus, one of the base rows has a majority of
components being emitters, and the other base row has a majority of
components being detectors. Thereby more detection lines can be
obtained, whereby size of spatial and/or angular gaps, e.g. around
the centre line C, in the grid of propagation paths can be
reduced.
[0024] According to a further embodiment, the base rows comprise
one row with only emitters and one row with only detectors. The
components of the apparatus may be sensitive to disturbances. The
detectors are to detect the energy propagating in the panel, and
the detected energy might be of a small quantity compared to
disturbances e.g. from the emitters or ambient light or noise. By
having a base row with almost only detectors the risk that the
detected energy, detected with the detectors, becomes disturbed by
the emitters is reduced as the emitters are located more distant
from the detectors than before.
[0025] According to one embodiment, at least one of the base rows
comprises at least 80% emitters or detectors, more preferably at
least 90% emitters or detectors.
[0026] According to one embodiment, at least one of the base rows
has a random distribution of emitters and/or detectors.
[0027] According to one embodiment, "interleaved distribution" is
defined by a consecutive, non-overlapping distribution of
alternating blocks with components being either only emitters or
only detectors, wherein each block B comprises a maximum of two or
three components. Thus, any adjacent blocks have different types of
components. The type of "interleaved distribution" can be varied.
According to one embodiment, the interleaved distribution is of a
type single interleaved, wherein each block B comprises only one
component. According to another embodiment, the interleaved
distribution is of a type multiple interleaved, wherein each block
B comprises a same multiple of components. According to a further
embodiment, the interleaved distribution is of a type
semi-interleaved, wherein blocks with the same type of components
has the same number of components, and wherein the number of
emitters in a block B is not the same as the number of detectors in
another block B. According to a still further embodiment, the
interleaved distribution is of a type irregular-interleaved,
wherein the number of components in each block B is irregularly
chosen. For example, the number of components in each block B may
be randomly chosen.
[0028] According to one embodiment, each emitter is being operable
for propagating a diverging beam. According to a further
embodiment, each emitter is being operable for propagating a
diverging beam with a beam diverging angle .alpha. from
.+-.45.degree. to .+-.90.degree. from a normal of a beam direction
surface of the emitter, the beam diverging angle .alpha. being
parallel to the touch surface. For example, the diverging angle may
be .+-.45.degree., .+-.60.degree., .+-.75.degree. or
.+-.90.degree..
[0029] According to one embodiment, the components are
electro-optical components that are configured to generate
radiation and/or energy and detect radiation and/or energy,
respectively.
[0030] According to one embodiment, each detector is being operable
for detecting transmitted energy from at least two emitters.
According to one embodiment, each detector is configured to receive
energy within a range of angles of incidence. In one
implementation, each emitter is configured to generate radiation
and is optically coupled to the panel so as to propagate a
diverging beam of radiation across the touch surface by internal
reflections inside the panel, and wherein each detector is
configured to detect radiation and is optically coupled to the
panel so as to detect transmitted radiation from the at least two
emitters.
[0031] According to one embodiment, said first set of rows of
components and said second set of rows of components define a
perimeter of non-overlapping and consecutive components around the
touch surface. According to a further embodiment, the touch surface
has a rectangular form, and each opposite and parallel row of
components of the first set is arranged along one short side of the
touch surface, and wherein each opposite and parallel row of
components of the second set is arranged along one long side of the
touch surface.
[0032] According to one embodiment, each row comprises at least 20
components, and preferably at least 30 components.
[0033] Preferred embodiments are set forth in the dependent claims
and in the detailed description.
SHORT DESCRIPTION OF THE APPENDED DRAWINGS
[0034] Below the invention win be described in detail with
reference to the appended figures, of which:
[0035] FIGS. 1A-1B are section and top plan views of an optical
touch-sensitive apparatus.
[0036] FIG. 2 is a 3D plot of an attenuation pattern generated
based on energy signals from an optical touch-sensitive
apparatus.
[0037] FIG. 3A is a top plan view of a grid of detection lines in a
prior art apparatus for one type of arrangement with opposite and
parallel rows with interleaved emitters and detectors.
[0038] FIG. 3B is a top plan view of a grid of detection lines in
an apparatus which is designed in accordance with embodiments of
the invention.
[0039] FIG. 4A is a top plan view of a grid of detection lines in a
prior art apparatus with an arrangement with orthogonal rows with
interleaved emitters and detectors.
[0040] FIG. 4B is a top plan view of a grid of detection lines in
an apparatus which is designed in accordance with embodiments of
the invention.
[0041] FIGS. 5-7 are top plan views of grids of detection lines in
an apparatus which is designed in accordance with embodiments of
the invention.
[0042] FIGS. 8A-8C are illustrating different interleaved
distributions according to some embodiments.
[0043] FIG. 9 is illustrating a beam diverging angle u from an
emitter.
[0044] FIG. 10 is illustrating detection lines within a certain
distance to a point on a touch surface.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0045] In the following, examples of the present invention will be
given in relation to a touch-sensitive apparatus designed to
operate by light transmission. Throughout the description, the same
reference numerals are used to identify corresponding elements.
[0046] FIGS. 1A-1B illustrates an example embodiment of a
touch-sensitive apparatus 100 that is based on the concept of FTIR
(Frustrated Total Internal Reflection). The apparatus 100 operates
by transmitting light inside a panel L from light emitters 2 to
light sensors or detectors 3, so as to illuminate a touch surface 4
from within the panel 1. The panel 1 is made of solid material in
one or more layers and may have any shape. The panel 1 defines an
internal radiation propagation channel, in which light propagates
by internal reflections. In the example of FIG. 1, the propagation
channel is defined between the boundary surfaces 5, 6 of the panel
1, where the top surface 5 allows the propagating light to interact
with touching objects 7 and thereby defines the touch surface 4.
This is achieved by injecting the light into the panel 1 such that
the light is reflected by total internal reflection (TIR) in the
touch surface 4 as it propagates through the panel 1. The light may
be reflected by TIR in the bottom surface 6 or against a reflective
coating thereon. It is also conceivable that the propagation
channel is spaced from the bottom surface 6, e.g. if the panel
comprises multiple layers of different materials. The apparatus 100
may be designed to be overlaid on or integrated into a display
device or monitor (not shown).
[0047] The apparatus 100 allows an object 7 that is brought into
close vicinity of, or in contact with, the touch surface 4 to
interact with the propagating light at the point of touch. In this
interaction, part of the light may be scattered by the object 7,
part of the light may be absorbed by the object 7, and part of the
light may continue to propagate in its original direction across
the panel 1. Thus, the touching object 7 causes a local frustration
of the total internal reflection, which leads to a decrease in the
energy (or equivalently, the power or intensity) of the transmitted
light, as indicated by the thinned lines `T` downstream of the
touching objects 7 in FIG. 1A.
[0048] The emitters 2 are distributed along the perimeter of the
touch surface 4 to generate a corresponding number of light sheets
inside the panel 1. Each light sheet is formed as a beam of light
that expands (as a "fan beam") in the plane of the panel 1 while
propagating in the panel 1 from a respective incoupling
region/point on the panel 1. The detectors J are distributed along
the perimeter of the touch surface 4 to receive the light from the
emitters 2 at a number of spaced-apart outcoupling regions/points
on the panel 1. It should be understood that the incoupling and
outcoupling regions/points merely refer to the positions where the
beams enter and leave, respectively, the panel 1. The light from
each emitter 2 will propagate inside the panel 1 to a number of
different detectors 3 on a plurality of light propagation paths D.
Even if the light propagation paths D correspond to light that
propagates by internal reflections inside the panel 1, the light
propagation paths D may conceptually be represented as "detection
lines" that extend across the touch surface 4 between pairs of
emitters 2 and detectors 3, as shown in FIG. 1B. Thereby, the
emitters 2 and detectors 3 collectively define a grid of detection
lines D ("detection grid") on the touch surface 4. The spacing of
detection lines in the detection grid may define the spatial
resolution of the apparatus 100, i.e. the smallest object that can
be detected on the touch surface 4.
[0049] The detectors 3 collectively provide an output signal, which
is received and sampled by a signal processor 10. The output signal
contains a number of sub-signals, also denoted "projection
signals", each representing the energy of light emitted by a
certain light emitter 2 and received by a certain light detector 3.
Depending on implementation, the signal processor 10 may need to
process the output signal for separation of the individual
projection signals. The projection signals represent the received
energy, intensity or power of light received by the detectors 3 on
the individual detection lines D. Whenever an object touches a
detection line, the received energy on this detection line is
decreased or "attenuated".
[0050] The signal processor 10 may be configured to process the
projection signals so as to determine a property of the touching
objects, such as a position (e.g. in the x. y coordinate system
shown in FIG. 1B), a shape, or an area. This determination may
involve a straight-forward triangulation based on the attenuated
detection lines, e.g. as disclosed in U.S. Pat. No. 7,432,893 and
WO2010/015408, or a more advanced processing to recreate a
distribution of attenuation values (for simplicity, referred to as
an "attenuation pattern") across the touch surface 1, where each
attenuation value represents a local degree of light attenuation.
An example of such an attenuation pattern is given in the 3D plot
of FIG. 2. The attenuation pattern may be further processed by the
signal processor 10 or by a separate device (not shown) for
determination of a position, shape or area of touching objects. The
attenuation pattern may be generated e.g. by any available
algorithm for image reconstruction based on projection signal
values, including tomographic reconstruction methods such as
Filtered Back Projection, FFT-based algorithms, ART (Algebraic
Reconstruction Technique), SART (Simultaneous Algebraic
Reconstruction Technique), etc. Alternatively, the attenuation
pattern may be generated by adapting one or more basis functions
and/or by statistical methods such as Bayesian inversion. Examples
of such reconstruction functions designed for use in touch
determination arc found in WO2009/077962, WO2011/049511,
WO2011/139213, WO2012/050510 and US2014/0300572, all of which are
incorporated herein by reference. Conventional image reconstruction
techniques are found in the mathematical literature, e.g. "The
Mathematics of Computerized Tomography" by Natterer, and
"Principles of Computerized Tomographic Imaging" by Kak and
Slaney.
[0051] In the illustrated example, the apparatus 100 also includes
a controller 12 which is connected to selectively control the
activation of the emitters 2 and, possibly, the readout of data
from the detectors 3. Depending on implementation, the emitters 2
and/or detectors 3 may be activated in sequence or concurrently,
e.g. as disclosed in WO2010/064983. The signal processor 10 and the
controller 12 may be configured as separate units, or they may be
incorporated in a single unit. One or both of the signal processor
10 and the controller 12 may be at least partially implemented by
software executed by a processing unit 14.
[0052] It is to be understood that FIG. 1 merely illustrates one
example of a touch-sensitive apparatus. For example, instead of
injecting and detecting light via the edge surface that connects
the boundary surfaces 5, 6, light may be coupled into and/or out of
the panel 1 via the top and/or bottom surfaces 5, 6, e.g. by the
use of dedicated coupling elements attached to the panel 1. It is
also conceivable that the light is coupled into and out of the
panel 1 through different portions of the panel, e.g. via the
boundary surface 5 and the boundary surface 6, respectively.
Examples of alternative FTIR-based touch systems are e.g. disclosed
in U.S. Pat. No. 7,432,893, WO2010/046539, WO2012105893 and
WO2013/089622, which are all incorporated herein by this
reference.
[0053] Embodiments of the invention apply specific design rules for
the ordering of emitters 2 and detectors 3 along the perimeter of
the touch surface 4 to achieve desired properties of the detection
grid on the touch surface 4, as will be further explained in
relation to the top plan views in FIGS. 3-7. Each of the figures
illustrates a grid of detection lines that are defined between
horizontal rows 22A, 22B and vertical rows 20A, 20B of emitters
2\filled circles) and detectors 3 (filled squares) on ends or sides
of a touch surface. The components 2, 3 in any row are
consecutively arranged in a non-overlapping way. For ease of
presentation, the panel 1 and its touch surface 4 has been omitted
in FIGS. 3-7.
[0054] FIG. 3A is illustrating a conventional fan beam arrangement,
wherein emitters 2 and detectors 3 arc arranged in an alternating
fashion with equal spacing in two rows along opposite ends of the
touch surface 4, herein denoted "first interleaved arrangement".
The first interleaved arrangement results in a symmetric detection
grid, and each intersection point on the center line "C" between
the rows 22A, 22B contains a large number of detection lines. As
shown, this results in "gaps" in the detection grid.
[0055] FIG. 3B is illustrating two base rows 22A, 22B according to
one embodiment, where the base rows 22A, 22B are arranged in two
rows along opposite ends of the touch surface 4. One base row 22A
comprises only emitters 2 and the other base row 22B comprises only
detectors 3 with equal spacing. The number of components, and size
of spacing is the same as in FIG. 3A. The arrangement with base
rows with one row 22A with only emitters 2 and one row 22B with
only detectors 3 results in a symmetric detection grid, with "gaps"
in the detection grid that are smaller than the "gaps" in the
detection grid of FIG. 3A. Thus, the arrangement in FIG. 3B
provides an increased uniformity and reduced spacing of propagation
paths compared to the example shown in FIG. 3A.
[0056] FIG. 4A is illustrating another conventional fan beam
arrangement wherein emitters 2 and detectors 3 are arranged in
blocks B in an alternating fashion with equal spacing in two rows
20A, 22B along orthogonal ends of the touch surface 4, herein
denoted "second interleaved arrangement". Each block B comprises
one emitter 2 or detector 3. The second interleaved arrangement
results in a symmetric detection grid.
[0057] Another conventional fan beam arrangement that is not
illustrated in any figure is the "L-shaped" arrangement where two
rows are arranged with the same type of component 2, 3 along
orthogonal ends of a touch surface 4. Thus, two orthogonal rows are
arranged with detectors 3, and the other two orthogonal rows are
arranged with emitters 2. As understood by the: skilled person, the
orthogonal rows with the same type of component do not create any
detection lines that can be detected in between the rows, and a lot
of gaps with no propagation paths in large angular ranges are
obtained. However, it may be advantageous to have rows with only
one kind of component, or a majority of only one component, as it
is an arrangement that may be easier to implement.
[0058] FIG. 4B is illustrating one base row 22B and one interleaved
row 20A arranged along orthogonal ends of the touch surface 4. The
base row 22B comprises only detectors 3 with equal spacing, and the
interleaved row 20A comprises emitters 2 and detectors 3 arranged
in an alternating fashion with equal spacing. The interleaved row
20A is subdivided into blocks B. here with one emitter 2 or
detector 3 in each block B. The arrangement results in a detection
grid with essentially the same number of detections lines as in the
detection grid in FIG. 4A. The detection lines in FIG. 4B are
however offset compared to the detection lines in FIG. 4A. Compared
to the embodiment in FIG. 4A, the arrangement in FIG. 4B provides
new detection lines from emitters 2 in the interleaved row 20A to
the detectors 3 in the base row 22B, but loses detection lines from
emitters 2 in the base row to detectors 3 in the interleaved row
20A. Compared to the "L-shaped" arrangement (not shown), the
arrangement in FIG. 4B provides more evenly distributed detection
lines on the touch surface 4, contributing to an improved spatial
resolution. Compared to the arrangement of FIG. 4A the arrangement
of FIG. 4B may create more gaps in the detection grid. However,
when combined with two or more rows of components along the other
opposite ends of the touch surface 4 the arrangement of FIG. 4B may
create fewer and/or smaller gaps than an arrangement of four
interleaved rows, as will be discussed with reference to FIGS. 5
and 6.
[0059] The embodiments shown in FIGS. 3B and 4B have been
illustrated with components arranged along only two ends of the
touch surface 4 to illustrate genera] benefits with the embodiments
arranged according to certain design rules. The embodiments in
FIGS. 3B and 4B can be combined to benefit from a resulting
symmetric and enhanced detection grid obtained when four ends or
the touch surface 4 each is aligned with a row 20A, 20B, 22A, 22B
of components 3, 4. Two of the rows 20A, 20B, 22A, 22B are
interleaved rows each having an interleaved distribution of
emitters 2 and detectors 3, and the further two rows 20A, 208, 22A,
22B are base rows each having a distribution of components 2, 3
comprising at least 70% emitters 2 or detectors 3.
[0060] The above-described general design principle for the
touch-sensitive apparatus makes it possible to achieve an increased
spatial resolution and/or accuracy of the touch-sensitive apparatus
without increasing the number of components per unit length. Thus,
embodiments of the invention make it possible to attain a higher
spatial resolution and/or accuracy for a given number of
electro-optical components (emitters and detectors). The resolution
is improved with a denser detection grid and the accuracy is
improved when the detection lines are distributed over a large
angular range. To obtain a certain spatial resolution and accuracy,
it is desired that each point on the touch surface shall have a
certain number of detection lines within a certain distance d to
that point, and with a distribution of angles for the detection
lines. FIG. 10 illustrates an enlarged view of a point P on the
touch surface with a number of nearby detection lines D within the
certain distance d to the point. The detection lines are angularly
distributed. There are however angular gaps .beta. between the
detection lines, where there are no detection lines. These angular
gaps .beta. reduces the accuracy. The angular gaps .beta. between
the detection lines should therefore be small, so each point on the
touch surface may have detection lines with angular gaps of less
than 20.degree., preferably less than 10.degree. or 5.degree.,
between the detection lines within a certain distance d to the
point when the touch apparatus is being operated. The distance d
may e.g. be an approximated radius of a fingerpalm.
[0061] In FIG. 5 an embodiment is illustrated comprising a first
set of opposite and essentially parallel rows 20A, 20B of
components 2, 3 and a second set of opposite and essentially
parallel rows 22A, 22B of components 2, 3. The second set of
opposite and parallel rows 22A, 22B is essentially orthogonal to
the first set of opposite and parallel rows 20A, 20B. In this
embodiment the interleaved rows constitute the first set of
opposite and parallel rows 20A, 20B. The base rows then constitute
the second set of opposite and parallel rows 22A, 22B. One base row
22A comprises only emitters 2 and thus has a distribution of
components 2, 3 of 100% emitters 2. The other base row 22B
comprises only detectors 3 and thus has a distribution of
components 2, 3 of 100% detectors 3. The base rows 22A, 22B may
have another distribution of components 2, 3, however at least 70%
emitters 2 or detectors 3 each. The interleaved rows 20A, 20B are
of the type single interleaved, wherein each block B comprises only
one component 2, 3. The touch surface 4 here has a rectangular
form, and each of the rows 20A, 20B of components 2, 3 of the first
set is arranged along one short side of the touch surface 4, and
each row 22A, 22B of components 2, 3 of the second set is arranged
along one long side of the touch surface 4. An apparatus with an
arrangement as illustrated in FIG. 5 may thus have the drawback of
larger gaps in the detection grid as illustrated in FIG. 4B, but
will also have the benefits of the detection grid as illustrated in
FIG. 3B and explained in the text thereto. The combination of the
arrangements of FIGS. 3B and 4B gives a detection grid with
generally smaller spatial gaps and smaller angular gaps, as
compared to a combination of the arrangements of FIGS. 3A and 4A
with four interleaved rows at four ends of a touch surface 4.
[0062] In FIG. 6 a further embodiment is illustrated comprising a
first set and a second set of components in similarity with the
embodiment shown in FIG. 5. However, in this embodiment the
interleaved rows constitute one row 20B of the first set of
opposite and parallel rows 20A, 20B, and one row 22A of the second
set of opposite and parallel rows 22A, 22B. The base rows then
constitute the other row 20A of the first set of opposite and
parallel rows 20A, 20B, and the other row 22B of the second set of
opposite and parallel rows 22A, 22B. One base row 20A comprises
only emitters 2 and thus bas a distribution of components 2, 3 of
100% emitters 2. The other base row 22B comprises only detectors 3
and thus has a distribution of components 2, 3 of 100% detectors 3.
The base rows 20A, 22B may have another distribution of components
2, 3, however at least 70% emitters 2 or detectors 3 each. The
interleaved rows 20B, 22A are of the type single interleaved,
wherein each block B comprises only one component 2, 3. The touch
surface 4 here has a rectangular form, and in similarity with the
embodiment in FIG. 5, each of the rows 20A, 20B of components 2, 3
of the first set is arranged along one short side of the touch
surface 4, and each row 22A. 22B of components 2, 3 of the second
set is arranged along one long side of the touch surface 4. This
arrangement of components also gives a detection grid with
generally smaller spatial gaps and smaller angular gaps, as
compared to the combination of the arrangements of FIGS. 3A and 4A
with four interleaved rows at four ends of a touch surface 4.
[0063] In FIG. 7 a still further embodiment is illustrated
comprising a first set and a second set of components in similarity
with the embodiments shown in FIGS. 5 and 6. Also, as in the
embodiment shown in FIG. 5, the interleaved rows constitute the
first set of opposite and parallel rows 20A, 20B. The base rows
then constitute the second set of opposite and parallel rows 22A,
22B. One base row 22A comprises a number of 17 emitters 2 out of 20
components, thus more than 70% of emitters 2. The other base row
22B comprises a number of 17 detectors 3 out of 20 components in
the base row 22B, thus more than 70% of detectors 3. The components
2, 3 in the interleaved rows 20A, 20B are subdivided into blocks B.
The interleaved rows 20A, 20B are here of the type
irregular-interleaved, wherein the numbers of components 2, 3 in
each block B is irregularly chosen. The number of components 2, 3,
may e.g. be chosen according to an optimization scheme, depending
e.g. on the total available number of components 2, 3, size of
touch surface, desired resolution of touch surface etc. According
to one embodiment, the number of components 2, 3 in each block B
may be randomly chosen. Each block B comprises one, two or three
components 2, 3 of either the type emitter 2 or detector 3. Thus,
each block B contains only emitters 2 or detectors 3. Adjacent
blocks B have a different type of component 2, 3. As can be seen in
the FIG. 7, the interleaved row 20A to the left in the Figure has a
plurality of blocks B with only one emitter 2 or detector 3, and
one block B with two detectors 3 and one block B with two emitters
2. The interleaved row 20B to the light in the Figure has a
plurality of blocks B with only one emitter 2 or detector 3, and
two blocks B with two detectors 3 and two blocks B with two
emitters 2. In similarity with FIGS. 5 and 6, the touch surface 4
has a rectangular form, and each of the rows 20A, 20B of components
2, 3 of the first set is arranged along one short side of the touch
surface 4, and each row 22A, 22B of components 2, 3 of the second
set is arranged along one Jong side of the touch surface 4. Other
examples of arrangements of components within a row are found in
WO2013176614 and WO2013176613, which are incorporated herein by
reference.
[0064] When the apparatus is provided with communicating
possibilities, e.g. integrated into a laptop or smartphone,
disturbances such as electrostatic discharge (ESD) from antennas
might disturb the detected energy. This problem increases when the
detectors 2 are located close to the antennas. In the embodiments
described, one of the ends of the touch surface 4 will have a base
row with less number of detectors 3, or no detectors 3 at all. This
base row may be arranged to be closest to the antenna/antennas,
e.g. on the most distal end of the touch surface 4. For example,
this distal end may be dose to an upper edge of a laptop comprising
a display with touch-sensitive capabilities as initially described.
Also, this distal end may become more exposed to other ambient
disturbances, making it more suitable for emitters 3 that may be
less sensitive to disturbances than detectors 2.
[0065] FIGS. 8A-8C are illustrating examples of interleaved
distributions of the interleaved rows according to some
embodiments. The principles of these interleaved distributions can
be used to arrange the components in the interleaved rows in any of
the herein described embodiments. In FIGS. 8A-8C only some
components 2, 3 are illustrated to show the principle, but it is
understood that the number of component can be increased or
decreased as desired to suit a certain design and/or size of touch
surface 4. FIGS. 8A-8B are illustrating interleaved distributions
of the type multiple interleaved, wherein each block B comprises
the same multiple of components. In the FIG. 8A each block B
comprises two emitters 2 only or two detectors 3 only. The blocks B
are then alternatingly arranged such that two adjacent blocks B do
not comprise the same type of components 2, 3. In the FIG. 8B each
block B comprises three emitters 2 only or three detectors 3 only.
The blocks B are then alternatingly arranged such that two adjacent
blocks B do not comprise the same type of components 2, 3. FIG. 8C
is illustrating an interleaved distribution of a type
semi-interleaved, wherein blocks B with the same type of components
2, 3 has the same number of components 2, 3, and wherein the number
of emitters 2 in a block B is not the same as the number of
detectors 3 in another block B. In FIG. 8C the number of detectors
3 in each block B with detectors is two, and the number of emitters
2 in each block B with only emitters is one. This example is shown
to illustrate the principle, and many alternatives of a
semi-interleaved distribution are possible. For example, the number
of detectors 3 in each block B with detectors may be one or three.
Further, the number of emitters 2 in each block B with emitters may
be two or three.
[0066] In the above-described embodiments, all components 2, 3 are
arranged with equi-distant center-to-center spacing within each
row. Such a design may facilitate manufacture of the
touch-sensitive apparatus. However, it is conceivable to achieve
further improvements in terms of uniformity and/or gap size of the
detection grid, by varying the spacing of the components 2, 3
within one or both of the interleaved rows. For example, the
spacing between different blocks may be varied so that the blocks
are arranged with alternating short/long spacing. Alternatively,
the blocks in the interleaved rows may be arranged spatially
separated from each other, which might enhance the spatial
resolution. Spatially separated blocks may be defined by having a
center-to-center spacing between adjacent components in different
blocks that is larger than a center-to-center spacing between
adjacent components within each block B. The components in each
block may also be arranged spatially separated from each other,
which also might enhance the spatial resolution. Spatially
separated components in a block may he defined by having a
center-to-center spacing between the adjacent components within the
block B that is larger than a center-to-center spacing between
adjacent components in different blocks B. Examples of spacings
between adjacent blocks are found in WO2013/176615, which is
incorporated herein by reference.
[0067] It should be noted that certain image reconstruction
techniques, e.g. tomographic techniques, may require (or benefit
from) a uniform angular distribution of detection lines on the
touch surface 4, i.e. that the detection lines that intersect a
respective reconstruction cell on the touch surface 4 are evenly
distributed in the angular direction, and possibly also that the
number of detection lines is approximately the same in all
reconstruction cells. A reconstruction cell denotes a sub-area of
the touch surface 4 which is assigned an attenuation value by the
reconstruction process. It has been revealed that the embodiments
described herein provide a detection grid with detection lines with
a mix of angles beneficial when reconstructing an image of the
touch surface.
[0068] As used herein, "horizontal", "vertical", "left" and "right"
merely refer to directions on the drawings and does not imply any
particular positioning of the panel 1.
[0069] According to one embodiment, the base rows may comprise one
row with X number of emitters 2 and one row with Y number of
detectors 3, wherein X is different from Y. Thus, a different
number of components 2, 3 of each type can be had on each base row.
In the above described embodiments, opposite rows have been
illustrated with an equal number of components. However, the number
of components on each side may be different.
[0070] As illustrated in FIG. 9, light from each emitter 2 may be
propagating inside the panel 1 as a diverging beam with a beam
diverging angle .alpha. from .+-.45.degree. to .+-.90.degree. from
a normal vector N of a beam direction surface 15 of the emitter 2.
The direction of the beam direction surface 15 determines the
overall direction of the diverging beam. Here, the beam direction
surface 15 is perpendicular to the touch surface 4, and the beam
diverging angle .alpha. is parallel to the touch surface 4. For
example, the diverging angle may be .+-.45.degree., .+-.60.degree.,
.+-.75.degree. or .+-.90.degree.. The diverging beam may also
diverge between the boundary surfaces 5, 6 of the panel 1, which is
not illustrated in the figure.
[0071] Symmetry artifact may arise close to the edges of the touch
surface 4, thus leaving gaps in the detection grid without
propagation paths. These gaps may be reduced by arranging one or
several extra components 2, 3, e.g. emitters 2, in any of the rows
such that light from the emitter or emitters 2 strikes the previous
gap in the detection grid. For example, in the arrangement in FIG.
4B one or several extra emitters 2 may be arranged in the base row
between detectors 3 and be arranged to project a beam of light in
the gap in the detection grid.
[0072] The present invention is not limited to the above-described
embodiments. Various alternatives, modifications and equivalents
may be used. For example, the touch surface 4 may have a
rectangular form with equally sized ends. Therefore, the above
embodiments should not be taken as limiting the scope of the
invention, which is defined by the appending claims.
* * * * *