U.S. patent application number 11/536403 was filed with the patent office on 2007-04-12 for interactive display devices and methods of making the same.
This patent application is currently assigned to INTEGRATED DIGITAL TECHNOLOGIES, INC.. Invention is credited to Sen-Shyong FANN.
Application Number | 20070080956 11/536403 |
Document ID | / |
Family ID | 37910328 |
Filed Date | 2007-04-12 |
United States Patent
Application |
20070080956 |
Kind Code |
A1 |
FANN; Sen-Shyong |
April 12, 2007 |
Interactive Display Devices And Methods Of Making The Same
Abstract
An interactive display device in one example may include: a
first substrate and a second substrate spaced apart from each other
for providing a display area; a plurality of display control
elements in a first matrix over the first substrate; a plurality of
first data lines over the first substrate, each of the first data
lines being coupled with one or more corresponding display control
elements; and a plurality of first scan lines over the first
substrate, each of the first scan lines being coupled with one or
more corresponding display control elements. Additionally, the
interactive display device may further include: a plurality of
photo sensors in a second matrix over the first substrate, the
photo sensors providing an interface for receiving input
information; a plurality of second data lines over the first
substrate, each of the second data lines being coupled with one or
more corresponding photo sensors; and a plurality of second scan
lines over the first substrate, each of the second scan lines being
coupled with one or more corresponding photo sensors for activating
the at least one corresponding photo sensor.
Inventors: |
FANN; Sen-Shyong; (Hsinchu,
TW) |
Correspondence
Address: |
AKIN GUMP STRAUSS HAUER & FELD L.L.P.
ONE COMMERCE SQUARE
2005 MARKET STREET, SUITE 2200
PHILADELPHIA
PA
19103
US
|
Assignee: |
INTEGRATED DIGITAL TECHNOLOGIES,
INC.
2F, No. 6, Prosperity Rd. 2 Hsinchu Science-Based Industrial
Park
Hsinchu
TW
|
Family ID: |
37910328 |
Appl. No.: |
11/536403 |
Filed: |
September 28, 2006 |
Current U.S.
Class: |
345/207 ;
257/E27.149 |
Current CPC
Class: |
G06F 3/042 20130101;
H01L 27/14681 20130101; G06F 3/0412 20130101 |
Class at
Publication: |
345/207 |
International
Class: |
G09G 5/00 20060101
G09G005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 7, 2005 |
TW |
094135169 |
Claims
1. An interactive display device comprising: a first substrate and
a second substrate spaced apart from each other for providing a
display area; a plurality of display control elements in a first
matrix over the first substrate, the display control elements
controlling the information displayed by the display area; a
plurality of first data lines over the first substrate, each of the
first data lines being coupled with at least one corresponding
display control element; a plurality of first scan lines over the
first substrate, each of the first scan lines being coupled with at
least one corresponding display control element; a plurality of
photo sensors in a second matrix over the first substrate, the
photo sensors providing an interface for receiving input
information; a plurality of second data lines over the first
substrate, each of the second data lines being coupled with at
least one corresponding photo sensor; and a plurality of second
scan lines over the first substrate, each of the second scan lines
being coupled with at least one corresponding photo sensor for
activating the at least one corresponding photo sensor.
2. The interactive display device according to claim 1, wherein the
interactive display device is coupled to a computing system that is
capable of providing the information being displayed by the display
area and being controlled by the input information received by the
interactive display device.
3. The interactive display device according to claim 1, wherein at
least some of the first scan lines also act as the second scan
lines.
4. The interactive display device according to claim 1, wherein at
least some of the first data lines also act as the second data
lines.
5. The interactive display device according to claim 1, wherein
each of the photo sensors comprises a photo transistor comprising:
a gate coupled to a corresponding second scan line; a drain region
coupled to one of a voltage source or the gate terminal; and a
source region coupled to a corresponding second data line.
6. The interactive display device according to claim 1, wherein
each of the photo sensors comprises a photo transistor comprising:
a photo transistor gate coupled to a voltage source; a photo
transistor drain region coupled to the voltage source; and a photo
transistor source region; and a switching transistor comprising: a
switching transistor gate coupled to a corresponding second scan
line; a switching transistor drain region coupled to the photo
transistor source region; and a switching transistor source region
coupled to a corresponding second data line.
7. The interactive display device according to claim 1, wherein the
first matrix and the second matrix are arranged so that the number
of the display control elements in a horizontal direction is x
times the number of the photo sensors in the horizontal direction
and the number of the display control elements in a vertical
direction is y times the number of the photo sensors in the
vertical direction, wherein each of x and y is an integer.
8. The interactive display device according to claim 1, wherein the
photo sensors provide location information of at least one of a
light beam projected onto the interactive display device and an
object or a shadow of the object on or near the interactive display
device, wherein at least one of the light beam and the object
provides an input information to the interactive display
device.
9. The interactive display device according to claim 1, wherein
each of the photo sensors comprises a dual-transistor photo
transistor having a gate, two source regions, and one shared drain
region.
10. The interactive display device according to claim 1, wherein
the photo sensors and the display control elements comprise
semiconductor components that are fabricated together.
11. The interactive display device according to claim 1, wherein
the second data lines are coupled to an object shadow analysis
circuit.
12. An interactive display device comprising: a first substrate and
a second substrate spaced apart from each other for providing a
display area; a plurality of display control elements in a first
matrix over the first substrate, the display control elements
controlling the information displayed by the display area; a
plurality of first data lines over the first substrate, each of the
first data lines being coupled with at least one corresponding
display control element; a plurality of first scan lines over the
first substrate, each of the first scan lines being coupled with at
least one corresponding display control element; a plurality of
photo sensors in a second matrix over the first substrate, the
photo sensors providing an interface for receiving input
information, wherein at least some of the first scan lines are
coupled to at least one corresponding photo sensor for activating
the at least one corresponding photo sensor; and a plurality of
second data lines over the first substrate, each of the second data
lines being coupled with at least one corresponding photo
sensor.
13. The interactive display device according to claim 12, wherein
the interactive display device is coupled to a computing system
that is capable of providing the information being displayed by the
display area and being controlled by the input information received
by the interactive display device.
14. The interactive display device according to claim 12, wherein
each of the photo sensors comprises a photo transistor comprising:
a gate coupled to a corresponding first scan line; a drain region
coupled to one of a voltage source or the gate terminal; and a
source region coupled to a corresponding second data line.
15. The interactive display device according to claim 12, wherein
each of the photo sensors comprises a photo transistor comprising:
a photo transistor gate coupled to a voltage source; a photo
transistor drain region coupled to the voltage source; and a photo
transistor source region; and a switching transistor comprising: a
switching transistor gate coupled to a corresponding first scan
line; a switching transistor drain region coupled to the photo
transistor source region; and a switching transistor source region
coupled to a corresponding second data line.
16. The interactive display device according to claim 12, wherein
the first matrix and the second matrix are arranged so that the
number of the display control elements in a horizontal direction is
x times the number of the photo sensors in the horizontal direction
and the number of the display control elements in a vertical
direction is y times the number of the photo sensors in the
vertical direction, wherein each of x and y is an integer.
17. The interactive display device according to claim 12, wherein
the photo sensors provide location information of at least one of a
light beam projected onto the interactive display device and an
object or a shadow of the object on or near the interactive display
device, wherein at least one of the light beam and the object
provides an input information to the interactive display
device.
18. The interactive display device according to claim 12, wherein
each of the photo sensors comprises a dual-transistor photo
transistor having a gate, two source regions, and one shared drain
region.
19. The interactive display device according to claim 12, wherein
the photo sensors and the display control elements comprise
semiconductor components that are fabricated together.
20. The interactive display device according to claim 12, wherein
the second data lines are coupled to an object shadow analysis
circuit.
21. An interactive display device comprising: a first substrate and
a second substrate spaced apart from each other for providing a
display area; a plurality of display control elements in a first
matrix over the first substrate, the display control elements
controlling the information displayed by the display area; a
plurality of first data lines over the first substrate, each of the
first data lines being coupled with at least one corresponding
display control element; a plurality of first scan lines over the
first substrate, each of the first scan lines being coupled with at
least one corresponding display control elements; a plurality of
photo sensors in a second matrix over the first substrate, the
photo sensors providing an interface for receiving input
information, wherein the second matrix overlap with a portion of
the first matrix so that some of the photo sensors are adjacent to
or in the proximity of some of the display control elements.
Description
RELATED FIELD OF THE INVENTION
[0001] The invention relates to a display device. More
specifically, the invention relates to interactive display devices
and methods of making the same.
BACKGROUND OF THE INVENTION
[0002] Display devices traditionally serve the role of displaying
the information or the output from a system, while other input
device or devices provide inputs to the system. Interactive
devices, such as a touch panel that can receive a user's input via
touching the display panel, combines both output and input
functions and allow a user to interact with the display or the
system coupled to the display. As an example, devices such as
personal digital assistants (PDAs), mobile phones, personal
computers (PCs), tablet PCs (PC), etc. have incorporated touch
panels for providing users with more choices in providing inputs to
or operate a system.
[0003] Conventional touch panels or touch screens have a number of
different designs, such as resistive type, surface-wave type,
capacitive type, and infrared-ray type designs. However, all of
these designs typically require combining a display device with a
separate touch panel sheet or structure, which may affect the
quality of the display, increase the weight and size of an existing
display device, and, usually unavoidably, significantly increase
the manufacturing cost and time of the combined device.
Additionally, the various designs also have associated drawbacks.
For example, certain touch panel designs require the panel to first
store a received input information in a capacitor before such
information is subsequently read. Such requirement, in some
examples, may occupy additional area by having additional touch
panel structure that provides the input-maintaining capacitors. The
design is not ideal, as it may reduce the aperture ratio of a
display device when area is limited and display efficiency or
brightness is desired. Additionally, depending on the panel design
and the dynamic ranges of input information, the capacitors
associated with the touch panel may not provide adequate dynamic
ranges for storing and identifying all ranges of inputs. As another
example, some designs may be vulnerable to non-input noises, such
as noises caused by the ambient light, the back light of the
displayed information itself, and other forms of electrical,
magnetic, or electromagnetic influence.
[0004] Therefore, there is a need for a display device that is
interactive while providing some advantages over or resolve one or
more drawbacks of traditional touch panels. For example, there may
be a need for interactive display devices with simplified
manufacturing processes, reduced sizes or thicknesses, or increased
dynamic ranges in receiving input devices of different kinds or
levels.
BRIEF SUMMARY OF THE INVENTION
[0005] Examples consistent with the present invention may provide
an interactive display device. In one example, the interactive
display device may include: a first substrate and a second
substrate spaced apart from each other for providing a display
area; a plurality of display control elements in a first matrix
over the first substrate; a plurality of first data lines over the
first substrate, each of the first data lines being coupled with
one or more corresponding display control elements; and a plurality
of first scan lines over the first substrate, each of the first
scan lines being coupled with one or more corresponding display
control elements. Additionally, the interactive display device may
further include: a plurality of photo sensors in a second matrix
over the first substrate, the photo sensors providing an interface
for receiving input information; a plurality of second data lines
over the first substrate, each of the second data lines being
coupled with one or more corresponding photo sensors; and a
plurality of second scan lines over the first substrate, each of
the second scan lines being coupled with one or more corresponding
photo sensors for activating the at least one corresponding photo
sensor.
[0006] In another example, an interactive display device may
include: a first substrate and a second substrate spaced apart from
each other for providing a display area; a plurality of display
control elements in a first matrix over the first substrate; a
plurality of first data lines over the first substrate, each of the
first data lines being coupled with one or more corresponding
display control elements; a plurality of first scan lines over the
first substrate, each of the first scan lines being coupled with
one or more corresponding display control elements. The display
control element may further include: a plurality of photo sensors
in a second matrix over the first substrate, the photo sensors
providing an interface for receiving input information; and a
plurality of second data lines over the first substrate, each of
the second data lines being coupled with one or more corresponding
photo sensors. In this example, some of the first scan lines may be
coupled to one or more corresponding photo sensors for activating
the corresponding photo sensors.
[0007] In still another example, an interactive display device may
include: a first substrate and a second substrate spaced apart from
each other for providing a display area; a plurality of display
control elements in a first matrix over the first substrate; a
plurality of first data lines over the first substrate, each of the
first data lines being coupled with one or more corresponding
display control elements; a plurality of first scan lines over the
first substrate, each of the first scan lines being coupled with
one or more corresponding display control elements; a plurality of
photo sensors in a second matrix over the first substrate, the
photo sensors providing an interface for receiving input
information, wherein the second matrix overlap with a portion of
the first matrix so that some of the photo sensors are adjacent to
or in the proximity of some of the display control elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic diagram illustrating an interactive
display in examples consistent with the invention;
[0009] FIG. 2A is a schematic diagram illustrating an example of
photo sensors used in an interactive display device in examples
consistent with the invention;
[0010] FIG. 2B is a schematic diagram illustrating another example
of photo sensors of used in an interactive display device in
examples consistent with the invention;
[0011] FIG. 3A is a cross-sectional diagram illustrating an
exemplary structure of a photo transistor;
[0012] FIG. 3B is an top view of the photo transistor illustrated
in FIG. 3A;
[0013] FIG. 3C is a top view showing a possible arrangement of
photo sensor regions without sharing a common drain;
[0014] FIG. 4A is a cross-sectional diagram illustrating an
exemplary structure of a photo sensor;
[0015] FIG. 4B is a top view of the photo sensor illustrated in
FIG. 4A; and
[0016] FIG. 4C is a top view showing a possible arrangement of
photo sensor regions of without sharing a common drain.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Examples consistent with the invention may provide
interactive display devices and the methods of forming interactive
display devices. The interactive display devices may have display
control elements arranged in a first matrix and photo sensors
arranged in a second matrix. In some examples, the photo sensors
may be fabricated together with display control elements such as
transistors or thin-film transistors ("TFTs") without requiring
additional semiconductor layers or structures to be formed over a
substrate. In other words, some examples allow the input or
interactive function of a display device be incorporated into a
display device without complicating the fabrication process or
significantly increasing the fabrication cost. In some examples, a
transistor having its gate and drain electrically coupled or two or
more transistors with similar configuration may be used for proving
photo transistors without occupying too much substrate area. In
some examples, interactive display devices may use the input
information for various applications, including recognizing
hand-writings, recognizing other inputted characters or drawings,
and identifying tapping, different forms of tapping or touching, or
multi-tapping for different applications. Additionally, interactive
display devices may accept various forms of input devices or
instruments, including a pen, a stylus, a finger, or any other
instruments.
[0018] FIG. 1 is a schematic diagram illustrating examples of an
interactive display device consistent with the invention. Referring
to FIG. 1, interactive display device 200 may include two
substrates 202 and 204 spaced apart from each other for providing a
display area therebetween. In addition, display device 200 may
include a number of display control elements 210 arranged in a
first matrix over substrate 202, and display control elements 210
may control the information displayed by the display area. Display
device 200 also include a number of first data lines 212 over
substrate 202, and each of first data lines 212 may be coupled with
at least one corresponding display control element 210. In the
example illustrated in FIG. 1, all the display control elements 210
in the same horizontal level (along the x direction) may be coupled
to one data line 212 that extends horizontally. Display device 200
also include a number of first scan lines 214 over substrate 202,
and each of the first scan lines 214 may be coupled with at least
one corresponding display control element 210. In the example
illustrated in FIG. 1, all the display control elements 210 along
the same vertical line (along the y direction) may be coupled to
one scan line 214 that extends vertically.
[0019] In addition to display control elements 210, display device
200 may also include a number of photo sensors 220 arranged in a
second matrix over the first substrate, and the photo sensors 220
may serve as an interface for receiving input information. Display
device 200 may also include a number of second data lines 222
(dashed, x-direction lines) over substrate 202, and each of the
second data lines 222 may be coupled with at least one
corresponding photo sensor. In one example, although the
interactive display device 200 may use separate data lines in many
applications, some of the first data lines 212 may be shared or
used as some of the second data lines 222, depending on the design.
In addition, in the example illustrated in FIG. 1, all the photo
sensors 220 in the same horizontal level (along the x direction)
may be coupled to one data line that extends horizontally. Display
device 200 may also include a number of second scan lines 224
(dashed, y-direction lines) over substrate 202, and each of the
second scan lines 224 may be coupled with at least one
corresponding photo sensor 220 for activating the at least one
corresponding photo sensor 220. In one example, some of the first
scan lines 214 may be shared or used as some of the second scan
lines 224, depending on the design. In addition, in the example
illustrated in FIG. 1, all the photo sensors 220 in the same
vertical position (along the y direction) may be coupled to one
scan line 224 that extends vertically.
[0020] In some examples, interactive display device 200 may be
coupled to a computing system that is capable of providing the
information being displayed by the display area and being
controlled by the input information received by the interactive
display device. Also, by using appropriate processing or sensing
circuit, photo sensors 220 may provide location information of a
light beam projected onto interactive display device 200 or of an
object or a shadow of the object on or near the interactive display
device. In other words, the light beam or the object may provide
input information to interactive display device 200.
[0021] FIG. 2A illustrates an example of photo sensors that may be
used in interactive display device 200 described above. Referring
to FIG. 2A, each of photo sensors 110, 120, 130, and 140 may be
arranged in a second matrix in combination with other display
elements that are not shown in FIG. 2A. Taking photo sensor 110 as
an example, it may include a photo transistor having gate terminal
11g, drain terminal 11d, and source terminal 11s. Source terminal
11s may be coupled to a corresponding data line 1D. Gate terminal
11g may be coupled to a corresponding scan line 1G, which may also
be referred to as a gate line in this example. Drain terminal 11d
may be coupled gate terminal 11g, which is coupled to scan line 1G
in the illustrated example. Alternatively, drain terminal 11d may
be coupled to a separate voltage source, which may provide a
voltage such as V.sub.DD for operating photo sensor 110. In one
example, scan line 1G controls when the corresponding photo sensor
or photo sensors 110 and 130 in the illustrated example in FIG. 2A,
are activated. The voltage provided to scan line 1G or a separate
voltage source coupled to the drain terminals of photo sensors, or
photo sensors 110 and 130 in the illustrated example in FIG. 2A,
provides a bias level that allows the photo sensors to sense the
illumination level or light intensity at or near where the photo
sensors are by varying their current flows based on the
illumination level. In one example, the activating bias or scan
line voltage can be about 10 to 15 volts and the non-activating
scan line voltage can be about 0 volts to -10 volts. However, these
voltages may vary depending on the voltage sources or driving
circuits available to the interactive display device and the design
or the components used for the interactive display device.
[0022] Referring to FIG. 2A, when photo sensor 110 is activated by
scan line 1G, first current 1C would flow from source terminal 11s
to indicate the illumination level or light intensity at that
location. In other words, the light intensity at or near pixel area
11 can be detected from the level of first current 1C when photo
sensor 110 is activated or "scanned" by scan line 1G. Similarly,
scan line 1G may activate photo sensor 130 at the same time and the
current flowing from its source terminal output through data line
2D may indicate the illumination level at or near pixel area 13. As
an example, if pixel area 11 is covered or shadowed by an object
from ambient light, first current 1C may be zero or minimal. In
contrast, if pixel area 11 is illuminated by ambient light or a
pointed light beam, first current 1C may be significant. In a
similar manner, when scan line 1G is not but scan line 2G is driven
or provided with an activating voltage, second current 2C would
flow from the source terminal of photo sensor 120 to indicate the
illumination level or light intensity at that location.
[0023] Accordingly, in this example, viewing an interactive display
device as a whole, the illumination levels at various areas of the
display device may be obtained by scanning all the scan lines,
usually sequentially. And the current flowing through the photo
sensors connected to the same data line may be read out at
different timing and processed accordingly, such as by a processing
or sensing circuit, which is illustrated in FIG. 2A. As a result,
with an appropriate current sensing or processing circuit, the
input from a light beam projected onto the display device or an
object, such as a pen, a finger, a stylus, or other devices,
touching or near the surface of the display device may be
received.
[0024] FIG. 2B illustrates another example of photo sensors that
may be used in interactive display device 200 described above.
Referring to FIG. 2B, each of the photo sensors for pixel areas 21,
22, 23, and 24 may be arranged in a second matrix in combination
with other display elements that are not shown in FIG. 2B. Taking
the photo sensor for pixel area 21 as an example, it may include
photo transistor 211 and switching transistor 212. Photo transistor
211 may detect the illumination level at the location, and
switching transistor 212 may control when the detected information
is read and output an associated sensing or processing circuitry.
Other photo sensors may be arranged similarly. Taking photo
transistor 211 as an example, it has source terminal 211s coupled
to drain terminal 212d of the corresponding switch transistor 212.
Gate terminal 211g of photo transistor 211 is coupled to a biased
voltage source, and drain terminal 211d of photo transistor 211 can
be coupled to the same biased voltage source or a separate voltage
source.
[0025] Referring to FIG. 2B, in one example, scan line 1G controls
when the corresponding photo sensor or photo sensors for pixel
areas 21 and 23 in the illustrated example, are activated. The
voltage provided to scan line 1G or a separate voltage source
coupled to the gate terminals of the switching transistors of those
photo sensors allows the photo sensors to sense the illumination
level or light intensity at or near where the photo sensors are. In
one example, the activating scan line voltage can be about 10 to 15
volts and the non-activating scan line voltage can be about 0 volts
to -10 volts. However, these voltages may be varied depending on
the voltage sources or driving circuits available to the
interactive display device and the design or the components used
for the interactive display device.
[0026] Referring to FIG. 2B, when the photo sensor for pixel area
21 is activated by scan line 1G, first current 1C would flow from
source terminal 211s, through switching transistor 212, to indicate
the illumination level or light intensity at that location. In
other words, the light intensity at or near the pixel area 21 can
be detected from the level of first current 1C when switching
transistor 212 is activated or "scanned" by scan line 1G.
Similarly, scan line 1G may activate the photo sensor for pixel
area 23 at the same time and the current flowing from the source
terminal of the corresponding photo transistor through data line 2D
may indicate the illumination level at or near pixel area 23. As an
example, if pixel area 21 is covered or shadowed by an object from
ambient light, first current 1C may be zero or minimal. In
contrast, if pixel area 21 is illuminated by ambient light or a
pointed light beam, first current 1C may be significant. In a
similar manner, when scan line 1G is not but scan line 2G is driven
or provided with an activating voltage, second current 2C would
flow from the source terminal of photo sensor 221 through switching
transistor 222 to indicate the illumination level or light
intensity at that location.
[0027] Accordingly, in this example, viewing an interactive display
device as a whole, the illumination levels at various areas of the
display device may be obtained by scanning all the scan lines,
usually sequentially. And the current flowing through the photo
sensors connected to the same data line may be read out at
different timing and processed accordingly, such as by a processing
or sensing circuit, which is illustrated in FIG. 2B. As a result,
with an appropriate current sensing or processing circuit, the
input from a light beam projected onto the display device or an
object, such as a pen, a finger, a stylus, or other devices,
touching or near the surface of the display device may be
received.
[0028] FIG. 3A is an exemplary cross-sectional diagram illustrating
a possible structure of a photo transistor. The illustrated
structure may provide a functional photo transistor using only a
limited semiconductor area, thereby achieving a high "area
efficiency." Referring to FIG. 3A, photo transistor 61 may include
a dual-transistor, flipped (upside-down) structure in the
illustrated example. Specifically, photo transistor 61 may include
common or shared gate 61b, gate dielectric layer 61h above common
gate 61b, channel region 61g above gate dielectric layer 61h, and
two source regions 61a and common or shared drain region 61c above
channel region 61g, with common drain region 61c between the two
source regions 61a and spaced apart from each of the two source
regions 61a horizontally. Common gate 61b may include a conductive
material such as polysilicon or metal, and the two source regions
61a and common drain region 61c may include doped silicon.
Additionally, channel region 61g may include an amorphous silicon
layer, and gate dielectric layer 61h may include a dielectric
layer, such as a silicon nitride layer. In one example, common gate
61b may be electrically coupled to common drain region 61c, which
may eliminate a parasitic capacitance commonly presented between
non-coupled gate and drain region. Also, by having the dual
transistor or dual source region structure, the effective channel
width of the photo transistor may be doubled without occupying the
area of two full photo transistors.
[0029] FIG. 3B is an exemplary top view illustrating the location
of different regions of photo transistor 61 illustrated in FIG. 3A.
Referring to FIG. 3B, drain region 61c is spaced apart from two
source regions 61a, and gate 61b lies approximately under drain
region 61c and extends roughly between two source regions. With the
structure, two photo transistors with a channel width of 1W, or
effectively one photo transistor with an equivalent channel width
of 2W, may be provided. In contrast, FIG. 3C shows an exemplary top
view illustrating the possible location of different regions of
photo transistor 62, which may be viewed as two separate but
parallel-coupled photo transistors, one at the left and the other
at the right. Referring to FIG. 3C, the photo transistor at the
left may include source region 62a, gate 62b, and drain 62c, and
the photo transistor at the right may include source region 62d,
gate 62e, and drain region 62f. Compared to the photo transistor
having electrically-coupled drain and gate as illustrated in FIG.
3B, the photo transistor illustrated in FIG. 3C occupies a bigger
surface area while providing a similar photo transistor with the
same channel width of 2W.
[0030] In some examples, the display function for an interactive
display device may be controlled by transistors, such as thin-film
transistors (TFTs). One example of the display device includes an
LCD (liquid crystal display) or TFT-LCD. As an example, the
fabrication of an LCD panel involves forming transistors and other
components over one substrate and combining the substrate with
another substrate to enclose liquid crystal, which may be
controlled by control elements such as TFTs, between the two
substrates. In this and some other examples, the photo sensors and
other display control elements of an interactive display device may
be fabricated together during the fabrication process, such as a
fabrication process involving forming semiconductor layers over a
substrate. In other words, the input function or interactive part
of the display device may be incorporated into a regular display
device without burdening or complicating the manufacturing process
of display devices. Furthermore, because the interactive display
devices in those examples would not require a separate sheet for
providing the touch panel or panel input function, the display
quality and reliability of the display devices may be improved.
[0031] FIG. 4A illustrates an exemplary cross-sectional view of a
photo sensor structure that was illustrated in FIG. 2B. Referring
to FIG. 4A, photo sensor 71 may include (1) a switching transistor
including gate 71e, drain region 71d, and source region 71f; and
(2) a photo transistor including common or shared gate 71b, source
regions 71a, and common or shared drain region 71c. In this
example, the photo transistor may similarly have a dual transistor
structure by sharing common drain region 71c and common gate 71b to
reduce the areas occupied by a photo transistor having an
equivalent channel width of 2W, as illustrated above in association
with FIG. 3A. Gate dielectric layer 71h and channel region 71g may
be provided between the gates and the source and drain regions as
illustrated in FIG. 4A. The materials for gates, source and drain
regions, gate dielectric layer, and channel region may be the same
or similar to the example described in association with FIG. 3A. In
this example, gate 71b may be electrically coupled to the shared
drain regions 71c in some examples, which may eliminate the
parasitic capacitance that is usually presented between
non-electrically-coupled gate and drain.
[0032] FIG. 4B is an exemplary top view illustrating the location
of different regions of the photo transistor illustrated in FIG.
4A. Referring to FIG. 4B, as a part of the photo transistor of
photo sensor 71, drain region 71c is spaced apart from two source
regions 71a and 71d, and gate 71b lies approximately under drain
region 71c and extends roughly between two source regions 71a and
71d. As part of the switching transistor of photo sensor 71, drain
region 71d is spaced apart from source region 71f, and gate 71e
lies under the two regions and extends roughly between the two
regions. With such structure for the photo transistor, two photo
transistors with a channel width of 1W, or effectively one photo
transistor with an equivalent channel width of 2W, may be provided.
In contrast, FIG. 4C shows an exemplary top view illustrating the
possible location of different regions of a photo transistor and a
switching transistor. Referring to FIG. 4C, a photo transistor may
be viewed as two separate but parallel-coupled photo transistors,
one at the left (72a, 72b, 72c) and the other at the right (72d,
72e, 72f), and a switching transistor (72a, 72g, and 72h) may be
appended to the photo transistor by sharing a common source region
72a. In particular, the photo transistor at the left may include
source region 72a, gate 72b, and drain 72c, and the photo
transistor at the right may include source region 72d, gate 72e,
and drain terminal 72f. Additionally, the switching transistor may
include drain region 72a, gate 72g, and source 72h. Compared to the
electrically coupled gate-drain photo transistor illustrated in
FIG. 4B, the photo transistor illustrated in FIG. 4C occupies a
bigger surface area while providing the same photo transistor with
a channel width of 2W.
[0033] As illustrated above, examples consistent with the invention
provide interactive display devices and the methods of forming
interactive display devices. In some examples, the photo sensors
may be fabricated together with display control elements such as
transistors or thin-film transistors without requiring additional
semiconductor layer to be formed over a substrate. As an example,
conventional processes of fabricating TFT-LCDs can be modified to
make interactive display devices by modifying a few
pattern-defining masks, such as the masks for defining the TFTs and
related components. Accordingly, the input or interactive function
of a display device may be added without complicating the
fabrication process or significantly increasing the fabrication
cost. Furthermore, effective channel widths of photo sensors or
photo transistors may be increased with the illustrated structures
without requiring too much additional substrate area.
[0034] Although the display control elements and the photo sensors
may be fabricated together, they do not need to be distributed over
a display device with the same density. That is, the density of the
photo sensors may be lower than the density of display control
elements. In other words, the first matrix containing display
control elements and the second matrix containing the photo sensors
can be arranged so that the second matrix generally overlaps with
only a portion of the first matrix. In one example, the number of
the display control elements in a horizontal direction is x times
the number of the photo sensors in the horizontal direction and the
number of the display control elements in a vertical direction is y
times the number of the photo sensors in the vertical direction.
Each of x and y may be integer in one example. For example, for a
display device having a resolution of 1280.times.1024 pixels, the
number of photo sensors can be 320.times.256 in one example or
256.times.128 in another example. And various other designs of
photo sensor distributions may be used depending on designs,
applications, or various other design considerations.
[0035] It will be appreciated by those skilled in the art that
changes could be made to the examples described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular examples disclosed, but it is intended to cover
modifications within the spirit and scope of the present
invention.
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