U.S. patent application number 14/556288 was filed with the patent office on 2015-03-26 for display device and electronic apparatus.
The applicant listed for this patent is SEMICONDUCTOR ENERGY LABORATORY CO., LTD.. Invention is credited to Yu Yamazaki.
Application Number | 20150084029 14/556288 |
Document ID | / |
Family ID | 34737312 |
Filed Date | 2015-03-26 |
United States Patent
Application |
20150084029 |
Kind Code |
A1 |
Yamazaki; Yu |
March 26, 2015 |
DISPLAY DEVICE AND ELECTRONIC APPARATUS
Abstract
According to one feature of the invention, a display device
comprises a pixel including a first sub-pixel having a first
light-emitting element and a second sub-pixel having a second
light-emitting element, a first source driver connected to a first
source line included in the first sub-pixel, and a second source
driver connected to a second source line included in the second
sub-pixel. The first sub-pixel and the second sub-pixel are
provided over one surface of a light-transmitting substrate, and a
first display region using the first sub-pixel over one surface of
the substrate and a second display region using the second
sub-pixel over the opposite surface the substrate are provided.
Accordingly, it is possible to provide a display device that
realizes sophistication and a high added value, which includes a
display region in each of one and the opposite sides.
Inventors: |
Yamazaki; Yu; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEMICONDUCTOR ENERGY LABORATORY CO., LTD. |
Atsugi-shi |
|
JP |
|
|
Family ID: |
34737312 |
Appl. No.: |
14/556288 |
Filed: |
December 1, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12269921 |
Nov 13, 2008 |
8907868 |
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14556288 |
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11032158 |
Jan 11, 2005 |
7453426 |
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12269921 |
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Current U.S.
Class: |
257/40 |
Current CPC
Class: |
G09G 2310/0251 20130101;
G09G 3/30 20130101; H04M 2250/52 20130101; G09G 2300/0809 20130101;
H01L 27/3211 20130101; G09G 2300/0426 20130101; H04M 2250/16
20130101; G09G 3/20 20130101; H01L 27/3267 20130101; H01L 51/5271
20130101; G09G 2310/0262 20130101; H04M 1/0214 20130101; G09G
2300/0443 20130101; G09G 2300/0465 20130101; H01L 27/322 20130101;
G09G 2310/0267 20130101; G09G 3/00 20130101; G09G 2300/0847
20130101 |
Class at
Publication: |
257/40 |
International
Class: |
H01L 27/32 20060101
H01L027/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2004 |
JP |
2004-007387 |
Claims
1. (canceled)
2. A device for displaying images comprising: a first body
comprising a display device; and a second body comprising an input
device, wherein the first body and the second body are connected
each other and rotatable around an axis, wherein the display device
comprises a first substrate, a second substrate, an
electroluminescent layer between the first substrate and the second
substrate and a sealant, wherein the first substrate and the second
substrate have light-transmitting properties and are bonded to each
other by the sealant, wherein the display device is configured to
display a first image from the first substrate and a second image
from the second substrate, and wherein the first image and the
second image is configured to be determined and changeable by
operating the input device.
3. The device for displaying images, according to claim 2, further
comprising a color filter on one or both of the first substrate and
the second substrate.
4. The device for displaying images, according to claim 2, further
comprising a color conversion layer on one or both of the first
substrate and the second substrate.
5. The device for displaying images, according to claim 2, selected
from the group consisting of a television apparatus, a digital
camera, a digital video camera, a cellular phone device, a portable
information terminal, a portable game machine, a monitor, a
personal computer, a tablet PC, an audio reproducing device, and an
image reproducing device provided with a recording medium.
6. The device for displaying images, according to claim 2, the
display device further comprising: a pixel comprising a first
sub-pixel having a first pixel electrode and a second sub-pixel
having a second pixel electrode; an opposite electrode overlapping
with the first pixel electrode and the second pixel electrode with
the electroluminescent layer interposed therebetween; a first
reflective layer; a second reflective layer; a first source driver
which supplies a first video signal for the first sub-pixel; and a
second source driver which is different from the first source
driver and supplies a second video signal for the second sub-pixel,
wherein there is the opposite electrode between the first pixel
electrode and the first reflective layer, wherein there is the
second reflective layer between the second pixel electrode and the
first substrate, and wherein the first pixel electrode, the second
pixel electrode and the opposite electrode have light-transmitting
properties.
7. The device for displaying images, according to claim 6, wherein
the first sub-pixel and the second sub-pixel is configured to emit
one of red, green, and blue light.
8. The device for displaying images, according to claim 6, wherein
the first sub-pixel and the second sub-pixel is configured to emit
white light.
9. The device for displaying images, according to claim 6, wherein
the first source driver is connected to a first digital data line
and the second source driver is connected to a second digital data
line.
10. The device for displaying images, according to claim 6, wherein
the first source driver is connected to a digital data line and the
second source driver is connected to an analog data line.
11. The device for displaying images, according to claim 6, wherein
the first source driver is connected to a first analog data line
and the second source driver is connected to a second analog data
line.
12. The device for displaying images, according to claim 2, the
display device further comprising: a pixel comprising a first
sub-pixel having a first pixel electrode and a second sub-pixel
having a second pixel electrode; an opposite electrode overlapping
with the first pixel electrode and the second pixel electrode with
the electroluminescent layer interposed therebetween; a reflective
layer; a first source driver which supplies a first video signal
for the first sub-pixel; and a second source driver which is
different from the first source driver and supplies a second video
signal for the second sub-pixel; wherein there is the opposite
electrode between the first pixel electrode and the reflective
layer, wherein the second pixel electrode has reflectiveness, and
wherein the first pixel electrode and the opposite electrode have
light-transmitting properties.
13. The device for displaying images, according to claim 12,
wherein the first sub-pixel and the second sub-pixel is configured
to emit one of red, green, and blue light.
14. The device for displaying images, according to claim 12,
wherein the first sub-pixel and the second sub-pixel is configured
to emit white light.
15. The device for displaying images, according to claim 12,
wherein the first source driver is connected to a first digital
data line and the second source driver is connected to a second
digital data line.
16. The device for displaying images, according to claim 12,
wherein the first source driver is connected to a digital data line
and the second source driver is connected to an analog data
line.
17. The device for displaying images, according to claim 12,
wherein the first source driver is connected to a first analog data
line and the second source driver is connected to a second analog
data line.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 12/269,921, filed Nov. 13, 2008, now allowed, which is a
divisional of U.S. application Ser. No. 11/032,158, filed Jan. 11,
2005, now U.S. Pat. No. 7,453,426, which claims the benefit of a
foreign priority application filed in Japan as Serial No.
2004-007387 on Jan. 14, 2004, all of which are incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a display device having a
self-luminous element.
[0004] 2. Description of the Related Art
[0005] In recent years, a display device having a self-luminous
element typified by electroluminescence (EL, Electro Luminescence)
element or the like has been developed. It is expected that this
display device be used widely by making the most of the advantage
such as a high image quality and a wide viewing angle because of
the self-luminous and thin shape and lightweight without the
necessity of a backlight. Incidentally, a high added value of a
mobile terminal is required by diversifying the purpose of use.
Recently, a mobile terminal equipped with a sub-display surface on
the side opposite to the ordinary display surface has been provided
(see Reference 1: Japanese Patent Laid-Open No. 2001-285445).
[0006] In a mobile terminal equipped with a sub-display surface in
addition to an original display surface, not only capacity occupied
by a module including a backlight or the like but also capacity
occupied by a printed wiring board or the like on which control ICs
for driving the original display surface and the sub-display
surface is mounted cannot be ignored. Particularly a mobile
terminal that is recently provided is remarkably made lighter and
more compact, which is a trade-off with a tendency to heighten the
added value.
SUMMARY OF THE INVENTION
[0007] Accordingly, in view of the above situation, an object of
the present invention is to provide a display device that realizes
a high added value by using a panel capable of downsizing the
capacity. In addition, an object of the invention is to provide a
display device that realizes sophistication.
[0008] The following means is taken according to the invention to
solve the above-mentioned conventional problem.
[0009] According to one of features of the invention, a display
device comprises a pixel including a first sub-pixel having a first
light-emitting element and a second sub-pixel having a second
light-emitting element, a first source driver connected to a first
source line included in the first sub-pixel, and a second source
driver connected to a second source line included in the second
sub-pixel. The first source driver supplies a first video signal
for the first sub-pixel, and the second source driver supplies a
second video signal for the second sub-pixel.
[0010] A pixel electrode and an opposite electrode of a first
light-emitting element have light-transmitting properties, a pixel
electrode of a second light-emitting element has reflectiveness, an
opposite electrode of the second light-emitting element has
light-transmitting properties, electroluminescent layers of the
first light-emitting element and the second light-emitting element
are provided in the same layer, the opposite electrodes of the
first light-emitting element and the second light-emitting element
are provided in the same layer, and a reflective layer overlapping
with the opposite electrode of the first light-emitting element is
provided.
[0011] In addition, according to one of features of the invention,
pixel electrodes and opposite electrodes of a first light-emitting
element and a second light-emitting element have light-transmitting
properties; electroluminescent layers of the first light-emitting
element and the second light-emitting element are provided in the
same layer; the opposite electrodes of the first light-emitting
element and the second light-emitting element are provided in the
same layer; and a first reflective layer overlapping with the
opposite electrode of the first light-emitting element, and a
second reflective layer overlapping with the pixel electrode of the
second light-emitting element are provided.
[0012] In addition to the above structures, according to another
feature of the invention, a display device comprises a gate driver
connected to a first gate line included in a first sub-pixel, and a
second gate line included in a second sub-pixel. This gate driver
controls operation of a transistor which controls supply of a video
signal for the first sub-pixel and the second sub-pixel.
Alternatively, according to another feature of the invention, a
first gate driver that is connected to a first gate line included
in the first sub-pixel and a second gate driver that is connected
to a second gate line included in the second sub-pixel are
provided. The first gate driver controls operation of a transistor
which controls supply of a first video signal for the first
sub-pixel. The second gate driver controls operation of a
transistor which controls supply of a second video signal for the
second sub-pixel.
[0013] According to another feature of a display device of the
invention, a first sub-pixel and a second sub-pixel are provided
over one surface of a light-transmitting substrate, and a first
display region with the use of the first sub-pixel over one surface
of the substrate and a second display region with the use of the
second sub-pixel over the surface opposite to the one surface of
the substrate are provided.
[0014] In addition, according to another feature of the invention,
the numbers of TFTs included in each of the first sub-pixel and the
second sub-pixel are the same. Alternatively, the numbers of TFTs
included in each of the first sub-pixel and the second sub-pixel
are different. Furthermore, according to another feature of the
invention, the first source driver is connected to a digital data
line or an analog data line, and the second source driver is
connected to a digital data line or an analog data line.
[0015] In addition, according to another feature of the invention,
the first light-emitting element and the second light-emitting
element emit red, green, or blue light. Alternatively, according to
another feature of the invention, the first light-emitting element
and the second light-emitting element emit white light, or the
first light-emitting element and the second light-emitting element
emit blue light.
[0016] In addition, according to another feature of the invention,
a color display is performed in the first display region, and a
color display is performed in the second display region.
Alternatively, according to another feature of the invention, a
color display is performed in the first display region and a
monochrome display is performed in the second display region, or a
monochrome display is performed in the first display region and a
monochrome display is performed in the second display region.
[0017] In addition, according to another feature of the invention,
a counter substrate which is opposed to the substrate is provided,
and a color filter is provided for one or both of one surface of
the substrate and one surface of the counter substrate. Moreover,
according to another feature of the invention, a counter substrate
which is opposed to the substrate is provided, and a color
conversion layer is provided for one or both of one surface of the
substrate and one surface of the counter substrate.
[0018] According to the invention having the above-mentioned
features, it is possible to provide a display device that realizes
sophistication and a high added value, which includes a display
region in each of the opposite sides. Capacity of the module can be
downsized compared with the case in which two panels are used to
equip each of the opposite sides with a display region. Therefore,
a display device in which small size, thin shape, and lightweight
are realized can be provided.
[0019] These and other objects, features and advantages of the
present invention will become more apparent upon reading of the
following detailed description along with the accompanied
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIGS. 1A and 1B are each a diagram illustrating Embodiment
Mode according to certain aspects of the present invention;
[0021] FIGS. 2A to 2C are each a view illustrating Embodiment Mode
according to certain aspects of the invention;
[0022] FIGS. 3A and 3B are each a diagram illustrating Embodiment 1
according to certain aspects of the invention;
[0023] FIGS. 4A and 4B are each a view illustrating Embodiment 2
according to certain aspects of the invention;
[0024] FIGS. 5A to 5D are each a view illustrating Embodiment 4
according to certain aspects of the invention;
[0025] FIGS. 6A to 6F are each a view illustrating Embodiment 4
according to certain aspects of the invention;
[0026] FIGS. 7A to 7D are each a view illustrating Embodiment 4
according to certain aspects of the invention;
[0027] FIG. 8 is a diagram illustrating Embodiment 5 according to a
certain aspect of the invention;
[0028] FIGS. 9A to 9E are each a diagram illustrating Embodiment 6
according to certain aspects of the invention and
[0029] FIGS. 10A to 10D are each a diagram illustrating Embodiment
Mode according to certain aspects of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Embodiment Mode of the present invention will be described
in detail with reference to the accompanying drawings. However, the
invention is not limited to the following explanations, and those
skilled in the art easily understand that the mode and details can
be variously changed without departing from the content and scope
of the invention. Therefore, the invention is not interpreted with
limiting to the description in this embodiment mode. Note that, in
the following explanations, reference numeral denoting the same
parts is used in common among different drawings.
Embodiment Mode
[0031] A display device of the invention has a pixel portion 30 in
which a plurality of first source lines Sa1 to Sam (hereinafter
referred to as source lines Sa1 to Sam, and "m" indicates a natural
number), a plurality of second source lines Sb1 to Sbm (hereinafter
referred to as source lines Sb1 to Sbm), a plurality of first gate
lines Ga1 to Gan (hereinafter referred to as gate lines Ga1 to Gan,
and "n" indicates a natural number), and a plurality of second gate
lines Gb1 to Gbn (hereinafter referred to as gate lines Gb1 to Gbn)
are arranged in a matrix (see FIG. 1A). The pixel portion 30
comprises a plurality of pixels 29 equipped with a first sub-pixel
12 (hereinafter referred to as a sub-pixel 12) in which a plurality
of elements is included in a region where a source line Sax ("x"
indicates a natural number, which satisfies 1.ltoreq.x.ltoreq.m)
and a gate line Gay ("y" indicates a natural number, which
satisfies 1.ltoreq.y.ltoreq.n) are intersected through an
insulator, and a second sub-pixel 14 (hereinafter referred to as a
sub-pixel 14) in which a plurality of elements is included in a
region where a source line Sbx and a gate line Gby are intersected
through an insulator.
[0032] The display device of the invention includes a first source
driver 15 (hereinafter referred to as a source driver 15) to be
connected to the plurality of source lines Sa1 to Sam, a second
source driver 16 (hereinafter referred to as a source driver 16) to
be connected to the plurality of source lines Sb1 to Sbm, a first
gate driver 27 (hereinafter referred to as a gate driver 27) to be
connected to the plurality of gate lines Ga1 to Gan, and a second
gate driver 28 (hereinafter referred to as a gate driver 28) to be
connected to the plurality of gate lines Gb1 to Gbm. The source
driver 15 supplies the sub-pixel 12 with a video signal, and the
source driver 16 supplies the sub-pixel 14 with a video signal. In
addition, the gate driver 27 supplies the sub-pixel 12 with a gate
selection signal, and the gate driver 28 supplies the sub-pixel 14
with a gate selection signal. The source drivers 15 and 16 and the
gate drivers 27 and 28 comprise a shift register, a latch, a
buffer, a sampling circuit, and the like.
[0033] According to the above-mentioned structure, the gate driver
27 that controls the sub-pixel 12 and the gate driver 28 that
controls the sub-pixel 14 are provided; however, the invention is
not limited to this structure. In other words, both the sub-pixels
12 and 14 may be controlled by one gate driver. Thus, a gate driver
to be connected to the plurality of gate lines Ga1 to Gan and the
plurality of gate lines Gb1 to Gbm may be provided.
[0034] The sub-pixel 12 includes a first light-emitting element 11
(hereinafter referred to as a light-emitting element 11), a
switching transistor 17 (hereinafter referred to as a TFT 17), and
a driving transistor 18 (hereinafter referred to as a TFT 18) in a
region where the source line Sax and the gate line Gay are
intersected through an insulator (see FIG. 1B). The sub-pixel 14
includes a second light-emitting element 13 (hereinafter referred
to as a light-emitting element 13), a switching transistor 19
(hereinafter referred to as a TFT 19), and a driving transistor 20
(hereinafter referred to as a TFT 20) in a region where the source
line Sbx and gate line Gby are intersected through an insulator.
Since the sub-pixels 12 and 14 having the above-mentioned structure
have two TFTs, respectively, of which number is small, enhancement
of a yield during the manufacturing process is achieved. In
addition, the pixels have advantage in terms of layout, and
enhancement of an aperture ratio is achieved.
[0035] The light-emitting elements 11 and 13 each have a structure
in which an electroluminescent layer is sandwiched between a pair
of electrodes. Among the pairs of electrodes included in each of
the light-emitting elements 11 and 13, one electrode is connected
to a power supply 31 through the TFT 18 or the TFT 20 and a power
supply line Vx, and the other electrode is connected to an opposite
power supply 32. Among the pairs of electrodes included in each of
the light-emitting elements 11 and 13, the electrodes connected to
the TFT 18 and 20 are referred to as pixel electrodes, and the
other electrodes are referred to as opposite electrodes. Note that,
in the above structure, the sub-pixels 12 and 14 have the power
supply line Vx in common. This structure achieves further
enhancement of the aperture ratio. However, the invention is not
limited to the above structure, and the power supply lines may be
provided separately in each of the sub-pixels 12 and 14.
[0036] The TFTs 17 and 19 each have the function of controlling
input of the video signals to each of the sub-pixels 12 and 14. The
signals are transmitted from the gate drivers 27 and 28 to the gate
electrodes of the TFTs 17 and 19 through the gate lines Gay and
Gby. Based on the signals transmitted from the gate drivers 27 and
28, each of the sub-pixels 12 and 14 are supplied with the video
signals from the source drivers 15 and 16 when the TFTs 17 and 19
are turned ON.
[0037] The TFTs 18 and 20 each have the function of controlling
each lighting or non-lighting of the sub-pixels 12 and 14. The gate
electrodes of the TFTs 18 and 20 are supplied with the video
signals through the TFTs 17 and 19. Based on the video signals, the
potential of the power supply line Vx is transmitted to the pixel
electrodes of the light-emitting elements 11 and 13 when the TFTs
18 and 20 are turned ON. Accordingly, a voltage of a forward bias
is applied between the both electrodes of the light-emitting
elements 11 and 13. Consequently, current flows to the
light-emitting elements 11 and 13, and thus, the luminescence is
obtained.
[0038] Although it is not shown in the figure, the sub-pixels 12
and 14 may be provided with a capacitor element that holds the
gate-source voltage (hereinafter referred to as VGS) of the TFTs 18
and 20. However, the capacitor that holds the VGS of the TFTs 18
and 20 may use a gate capacitor or a wiring capacitor. In addition,
the conductivity types of the TFTs 17 to 20 are not particularly
limited, and either N-type conductivity or P-type conductivity may
be accepted. Moreover, the circuit configuration of the sub-pixels
12 and 14 are not limited to the above, and various circuit
configurations are applicable. The structure except the above is
hereinafter described in Embodiments.
[0039] The display device of the invention are equipped with a
pixel portion 30 comprising a plurality of pixels including
sub-pixels 12 and 14 on one side of a light-transmitting substrate
33 (see FIG. 2A). A light-emitting element 11 included in the
sub-pixel 12 emits light in the direction of the substrate 33, and
a light-emitting element 13 included in the sub-pixel 14 emits
light in the opposite direction of the substrate 33. Accordingly, a
first display region using the sub-pixel 12 is provided on one side
of the substrate 33, and a second display region using the
sub-pixel 14 is provided on the side opposite to one side of the
substrate 33. In other words, the display device of the invention
has the display regions on one and the opposite sides of the
light-transmitting substrate 33, respectively.
[0040] The sub-pixel 12 is controlled by the source driver 15 and
the gate driver 27, and the sub-pixel 14 is controlled by the
source driver 16 and the gate driver 28. In other words, although
the sub-pixels 12 and 14 are provided over the substrate 33, the
sub-pixels are controlled by different drivers. Consequently,
different images can be displayed in the first display region and
the second display region, respectively. Of course, the same images
can be also displayed in the first display region and the second
display region.
[0041] In the case of the structure illustrated in above FIG. 2A,
the first display region using the sub-pixel 12 and the second
display region using the sub-pixel 14 are the same in size.
However, the invention is not limited to this structure. A pixel
portion 30 may be divided into a plurality of regions (two regions
in FIG. 10A), either a sub-pixel 12 or a sub-pixel 14 (only the
sub-pixel 14 in FIG. 10A) may be provided in a region 23, and the
both the sub-pixels 12 and 14 may be provided in a region 21 (see
FIGS. 10A and 10B). According to this structure, the size of the
first display region equals to the size shown in the region 21, and
the size of the second display region equals to the size shown in a
region 22. In other words, the first display region and the second
display region can be formed in different size from each other.
[0042] In addition, in the case of the structures shown in FIGS.
10A and 10B, only the sub-pixel 14 is provided without providing
the sub-pixel 12 in the region 23; however, the invention is not
limited to this structure. In a region 23, the sub-pixel 14 may be
formed in the place where the sub-pixel 12 is to be formed (see
FIGS. 10C and 10D). In this structure, also, the size of the first
display region equals to the size shown in a region 21, and the
size of the second display region equals to the size shown in a
region 22. In other words, the first display region and the second
display region can be formed in different size with each other.
However, according to this structure, the second display region has
different pixel density in the regions 21 and 23. Therefore, the
images displayed in the regions 21 and 23 may be appropriately
changed by, for example, providing an icon showing a remaining
battery level, wave intensity, or the like in the region 21 and
providing an e-mail message or the like in the region 23 of the
second display region.
[0043] Hereinafter, the structures of the light-emitting element 11
which emits light in the direction of the substrate 33 and the
light-emitting element 13 which emits light in the opposite
direction of the substrate 33 are explained with reference to
cross-sectional views by taking the two cases as examples (FIGS. 2B
and 2C). Note that, in the both cases, an electroluminescent layer
43 and an opposite electrode 41 of the light-emitting elements 11
and 13 are provided in the same layer.
[0044] First, as the first structure, the case in which both a
pixel electrode 40 and the opposite electrode 41 of the
light-emitting element 11 have light-transmitting properties, a
pixel electrode 42 of the light-emitting element 13 has
reflectiveness, and the opposite electrode 41 of the light-emitting
element 13 has light-transmitting properties is shown (see FIG.
2B). This structure has a feature that a reflecting layer 45
overlapping with the opposite electrode 41 of the light-emitting
element 11 is provided. According to the above feature, the
light-emitting element 11 emits light in the direction of the
substrate 33, and the light-emitting element 13 emits light in the
opposite direction of the substrate 33.
[0045] Next, a structure in which both a pixel electrode 40 and an
opposite electrode 41 of a light-emitting element 11 have
light-transmitting properties, and both a pixel electrode 51 and
the opposite electrode 41 of a light-emitting element 13 have
light-transmitting properties is shown (see FIG. 2C). This
structure has a feature that a first reflecting layer 50
overlapping with the opposite electrode 41 of the light-emitting
element 11 and a second reflecting layer 52 overlapping with the
pixel electrode 51 of the second light-emitting element 13 are
provided. According to the above feature, the light-emitting
element 11 emits light in the direction of a substrate 33, and the
light-emitting element 13 emits light in the opposite direction of
the substrate 33.
[0046] Note that materials having reflectiveness may be used for
the pixel electrode 42 having reflectiveness, the reflecting layer
45, the first reflecting layer 50, and the second reflecting layer
52. However, aluminum, which is superior in terms of reflectiveness
and which is inexpensive or a material containing the aluminum, is
preferably used. In addition, although FIG. 2B shows a structure in
which an insulating layer 44 which functions as a protective layer
is sandwiched between the opposite electrode 41 and the reflecting
layer 45, the invention is not limited to this structure. As shown
in FIG. 2C, the reflecting layer 45 may be provided to be in
contact with the opposite electrode 41. Moreover, the structure
shown in FIG. 2C uses a conductive layer in the same layer as gate
electrodes of TFTs 18 and 20 as the second reflecting layer 52;
however, the invention is not limited to this structure. In other
words, the second reflecting layer 52 may be provided in any layer
as long as it is formed below the pixel electrode 51. However, when
the second reflecting layer 52 is formed in a place apart from the
pixel electrode 51, unnecessary reflected light increases inside
the panel. Thus, in terms of efficiency in extracting light, the
second reflecting layer 52 may be formed to be in contact with the
pixel electrode 51, or the pixel electrode 51 may be formed from a
reflective material.
[0047] According to the invention having the above-mentioned
features, it is possible to provide a display device that realizes
sophistication and a high added value, which includes a display
region in each of one and the opposite sides. Capacity of the
module can be downsized compared with the case in which two panels
are provided on each of one and the opposite sides. Therefore, a
display device in which small size, thin shape, and lightweight are
realized can be provided.
Embodiment 1
[0048] In this embodiment, circuit configurations of the sub-pixels
are explained with reference to drawings. First, a structure
comprising three TFT's in a sub-pixel (3 TFT/Cell) is explained
(see FIG. 3A). This is a structure in which TFTs (erase TFTs) 61
and 62, gate lines Gcy (which satisfies 1.ltoreq.y.ltoreq.n, and "n
and y" indicate a natural number) and Gdy (which satisfies
1.ltoreq.y.ltoreq.m, and "y" indicates a natural number), and gate
drivers 63 and 64 are newly arranged in the structure shown in FIG.
1B. Current can be compulsorily made not to flow to light-emitting
elements 11 and 13 by arranging the TFTs 61 and 62. Therefore, a
lighting period can be started at the same time as or just after a
start of a writing period without waiting for writing a signal in
all sub-pixels. As a result, the duty ratio can be improved and a
favorable moving image display can be performed.
[0049] Next, a structure comprising four TFTs in a sub-pixel (4
TFT/Cell) is explained (see FIG. 3B). This is a structure in which
TFTs 65 and 66, a power supply line Vax (which satisfies
1.ltoreq.x.ltoreq.m, and "y" indicates a natural number), and a
power supply 67 are newly arranged in a structure shown in FIG. 3A.
The gate electrodes of the TFTs 65 and 66 are connected to the
power supply line Vax which is held in a constant potential. In
other words, the potentials of the gate electrodes of the TFTs 65
and 66 are fixed. The TFTs 65 and 66 are operated in a saturation
region to make current flow constantly. TFTs 18 and 20 are operated
in a linear region. According to the above-mentioned structure, the
value of a source-drain voltage (VDS) of the TFTs 18 and 20
operated in a linear region is small. Therefore, slight variation
between a gate-source voltage (VGS) of the driving TFTs 18 and 20
does not affect the values of current flown to the light-emitting
elements 11 and 13. Thus, the current values flown to the
light-emitting elements 11 and 13 depend on a source-drain current
of the TFTs 65 and 66 operated in a saturation region.
Consequently, luminance unevenness of the TFTs 65 and 66 due to
variation in characteristics of the TFTs 18 and 20 can be improved
to enhance the image quality. Note that a channel length L.sub.1
and a channel width W.sub.1 of the TFTs 18 and 20 and a channel
length L.sub.2 and a channel width W.sub.2 of the TFTs 65 and 66
may be set to satisfy L.sub.1/W.sub.1:L.sub.2/W.sub.2=5 to 6000:1
in order to operate each TFT in a linear region or a saturation
region.
[0050] Note that circuit configurations of sub-pixels 12 and 14
included in a pixel 29 may have the same structures (the same
number of TFTs) or may have different structures (the different
number of TFTs) from each other. In the case of the structures
different from each other, for example, 4 TFT/Cell may be employed
for sub-pixels which is included in a main display region for
displaying moving image or an image of high-definition is
performed, and 2 TFT/Cell may be employed for sub-pixels which is
included in a sub display region in which a still image display is
performed. In this manner, the circuit configurations may be
separately formed depending on the application of the display
regions. This embodiment can be arbitrarily combined with the
above-mentioned embodiment mode.
Embodiment 2
[0051] A panel, which is one mode of a display device of the
present invention, is explained with reference to drawings. Here, a
panel in which a pixel portion and a driver are integrally formed
is explained. The panel comprises a pixel portion 30, source
drivers 15 and 16, gate drivers 27 and 28, a connection terminal
72, and a connection film 71 provided over a substrate 33 (see
FIGS. 4A and 4B). The connection terminal 72 is connected to the
connection film 71 through conductive particles. The connection
film 71 is connected to an IC chip (not shown in the figure).
[0052] FIG. 4B shows a cross-sectional view taken along a line A-A'
of the panel and shows TFTs 18 and 20 and light-emitting elements
11 and 13 included in the pixel portion 30. In addition, elements
73 included in the source driver 15 and elements 74 included in the
source driver 16 are shown. A sealant 75 is provided in a periphery
of the pixel portion 30 and the drivers 15, 16, 27, and 28, and the
light-emitting elements 11 and 13 are sealed by sealant 75 and a
counter substrate 34. This sealing process is a process to protect
the light-emitting elements 11 and 13 from the substance that
becomes deteriorating factor, for example, moisture. Although a
method for sealing with the use of a cover material (glass,
ceramics, plastics, metal, or the like) is used here, a method for
sealing with the use of thermosetting resin or ultraviolet curable
resin may be used. Alternatively, a method for sealing with the use
of a thin film of which barrier ability is high, for example, metal
oxide, nitride, or the like may be used.
[0053] A TFT in which any one of an amorphous semiconductor, a
microcrystal semiconductor, a crystalline semiconductor, and an
organic semiconductor is employed for the channel portion is
acceptable to the elements formed over the substrate 33. However,
the elements are preferably formed from the crystalline
semiconductor superior in characteristics such as mobility in
comparison with the amorphous semiconductor. Accordingly,
monolithic device over one surface is achieved. Since the drivers
are integrally formed in the panel having the above structure, the
number of external ICs to be connected is decreased, and thus, a
small-size, thin-shaped, and lightweight display device is
realized.
[0054] Note that, in FIG. 4B, light emitted from the light-emitting
element 11 is emitted in the direction of the substrate 33 as
indicated by an arrow. Such a structure is referred to as a bottom
emission type. On the other hand, light emitted from the
light-emitting element 13 is emitted in the direction of the
counter substrate 34 as indicated by an arrow. Such a structure is
referred to as a top emission type. In addition, in FIG. 4B, each
of source electrodes or drain electrodes of the TFTs 18 and 20 and
the pixel electrodes of the light-emitting elements 11 and 13 are
laminated in the same layer without sandwiching an insulating layer
therebetween. According to this structure, regions where the pixel
electrodes of the light-emitting elements 11 and 13 are formed are
identical with a region excluding a region where the TFTs 18 and 20
are arranged. Accordingly, the decrease of aperture ratio is
inevitable due to high definition or the like of the pixel.
Therefore, an interlayer film may be additionally provided to
provide the pixel electrodes in the separated layer. Thus,
enhancement of the aperture ratio is achieved by effectively
utilizing the region where the TFTs are arranged.
[0055] In addition, an optical film such as a half-wave plate, a
quarter-wave plate, and a polarizing plate may be provided over one
surface of the substrate 33 and one surface of the counter
substrate 34. When a wave plate or a polarizing plate is provided,
unnecessary light generated due to reflection inside the panel is
reduced, and thus, a fine black display and a high contrast are
realized. An angle between two pieces of polarizing plates may be
range from 40.degree. to 90.degree., preferably from 70.degree. to
90.degree., and more preferably it may be set to 90.degree..
[0056] Note that the structure of the display device according to
the invention is not limited to the above description. For example,
the pixel portion 30 may comprise a TFT in which the amorphous
semiconductor serves as a channel portion, and the drivers 15, 16,
27, and 28 may comprise IC chips. The IC chips may be attached to
the substrate 33 by a COG method or may be attached to the
connection film 71 connected to the substrate 33. The amorphous
semiconductor can provide an inexpensive panel since it can be
easily formed over a large-sized substrate by using a CVD method
and a crystallization step is unnecessary. In addition, when a
droplet discharge method such as an ink-jet method is used in
conjunction in forming a conductive layer, a more inexpensive panel
can be provided. This embodiment can be arbitrarily combined with
the above-mentioned embodiment mode and embodiment.
Embodiment 3
[0057] According to the present invention, there are a first
display region on the side of a substrate 33 and a second display
region on the side of a counter substrate 34, and display in each
display region is explained with reference to Tables 1 and 2.
TABLE-US-00001 TABLE 1 Light Emitting Substrate 33 Side Counter
Substrate 34 Side Element (First Display Region) (Second Display
Region) RGB Light Color Display Color Display Emission White Light
CF Color CF Color Emission Display Display CF Color No CF
Monochrome Display Display No CF Monochrome CF Color Display
Display Blue Light Color Conversion Layer Color Color Conversion
Layer Color Emission Display Display Color Conversion Layer Color
No Color Conversion Layer Monochrome Display Display No Color
Conversion Layer Monochrome Color Conversion Layer Color Display
Display Monochromatic Monochrome Display Monochrome Display Light
Emission
[0058] In Table 1, RGB light emission indicates the case when light
emitted from a light-emitting element included in a pixel is red,
green, or blue. White light emission indicates the case when light
emitted from a light-emitting element included in a pixel is white.
Blue light emission indicates the case when light emitted from a
light-emitting element included in a pixel is blue. Monochromatic
light emission indicates the case when light emitted from a
light-emitting element included in a pixel is one color of red,
green, and the like. CF indicates a color filter. When the RGB
light emission is employed for a light-emitting element,
enhancement of light usage efficiency is achieved. In addition,
when white light emission or blue light emission is employed for
the light-emitting element, enhancement of a yield is achieved
since there is no necessity to color an electroluminescent layer
separately. Furthermore, when a CF or a color conversion layer is
employed, enhancement of a color purity or contrast is
achieved.
[0059] When the color filter and the color conversion layer are
employed, the color filter and the color conversion layer are
provided over one or both of one surface of the substrate 33 and
one surface of the counter substrate 34.
[0060] In both the first display region and the second display
region of a light-emitting element included in a pixel, color
display is performed in the case of RGB light emission or
monochrome display is performed in the case of monochromatic light
emission. When RGB light emission or monochromatic light emission
is performed in a light-emitting element included in a pixel, color
display or monochrome display is performed in both the first
display region and the second display region. When white light
emission or blue light emission is performed in a light-emitting
element included in a pixel, color display or monochrome display is
performed depending on existence or non-existence of the CF or the
color conversion layer. When the CF or the color conversion layer
is provided on one side of the substrate 33 and the counter
substrate 34, one of the substrates can perform color display and
the other can provide monochrome display.
TABLE-US-00002 TABLE 2 First Source Driver 15 Second Source Driver
16 (Substrate 33 Side, First Display Region) (Counter Substrate 34
Side, Second Display Region) Analog Video Signal Analog Display
Analog Video Signal Analog Display Analog Video Signal Analog
Display Digital Video Signal Digital Display Digital Video Signal
Digital Display Analog Video Signal Analog Display Digital Video
Signal Digital Display Digital Video Signal Digital Display
[0061] In Table 2, when both source drivers 15 and 16 supply each
sub-pixel with an analog video signal or a digital video signal,
the source drivers 15 and 16 are connected to an analog data line
which transmits the analog video signal or a digital data line
which transmits the digital video signal. Then, analog display or
digital display is performed in the first display region and the
second display region. In addition, when one of the source drivers
15 and 16 supplies an analog video signal and the other source
driver supplies a digital video signal, one of the source drivers
15 and 16 is connected to an analog data line and the other source
driver is connected to a digital data line. Then, analog display is
performed in one of the first display region and the second display
region, and digital display is performed in the other display
region.
[0062] Accordingly, analog display can be performed in one display
region and digital display can be performed in the other display
region by separately using signals that are supplied to each
sub-pixel by the source drivers 15 and 16. The display regions can
be separately formed in such a manner, for example, when a main
display region for displaying moving image or an image of
high-definition is provided by digital display, and a sub display
region for displaying a still image is provided by analog display.
Since the number of times of writing the signal is small in the
display region in which analog display is performed, power
consumption of the source drivers can be inhibited. In addition,
since the number of times of writing the signal is small, the
frequency of the source drivers can be reduced enough, and thus,
the signal writings can be performed accurately.
[0063] Note that, as mentioned above, either an analog video signal
or a digital video signal may be used in the display device of the
invention. However, in the case of using the digital video signal,
there are a video signal using the voltage and a video signal using
the current. In other words, the constant voltage or the constant
current is used for the video signal inputted into the pixel when a
light-emitting element emits light. When the constant voltage is
used for the video signal, the voltage applied to the
light-emitting element is constant, or the current flowing in the
light-emitting element is constant. On the other hand, when the
constant current is used for the video signal, the voltage applied
to the light-emitting element is constant, or the current flowing
in the light-emitting element is constant. The constant voltage
applied to the light-emitting element is referred to as constant
voltage driving, and the constant current flown to the
light-emitting element is referred to as constant current driving.
The constant current driving does not depend on the change of the
resistance and the constant current flows. Either the video signal
using the voltage or the video signal using the current may be used
for the display device of the invention, and either the constant
voltage driving or the constant current driving may be used. This
embodiment can be arbitrarily combined with the above-mentioned
embodiment mode and embodiments.
Embodiment 4
[0064] As an example of an electronic apparatus (electronic device)
to which a display device of the present invention is applicable, a
television apparatus (also referred to as a television receiver
device, a television receiver, a television, or a television
device), a camera such as a digital camera or a digital video
camera, a cellular phone device (also referred to as a cellular
phone handset or a cellular phone), a portable information terminal
such as a PDA (Personal Digital Assistant), a portable game
machine, a monitor, a personal computer, a tablet PC, an audio
reproducing device such as a car audio, an image reproducing device
provided with a recording medium such as a home-use game machine,
or the like is given. Hereinafter, the specific examples are
explained.
[0065] FIGS. 5A and 5B illustrate a tablet PC, which includes
display regions 9101 and 9102, buttons 9103, a rotation axis 9104,
and the like. The display region 9101 is used when the tablet PC is
in the unfolded state (FIG. 5A), and the display region 9102 is
used when the tablet PC is in the folded state (FIG. 5B). In
addition, both the display regions 9101 and 9102 may be used both
in the unfolded state and in the folded state by rotating the
casing with the use of the rotation axis 9104. The invention is
applicable to the display device including the display regions 9101
and 9102. FIGS. 5C and 5D illustrate a wristwatch portable
terminal, which includes display regions 9201 and 9202, a camera
9203, buttons 9204, a microphone 9205, a speaker 9206, and the
like. The invention is applicable to the display device including
the display regions 9201 and 9202.
[0066] FIGS. 6A to 6F illustrate a foldable portable terminal,
which includes a first casing 9311 having a speaker 9301 and a
panel 9307; a second casing 9312 having a microphone 9304, buttons
9303, and a camera 9316; and the like. In this portable terminal,
one or both of display regions 9305 and 9306 are used in the
unfolded state, and the display region 9306 is used in the folded
state. In addition, this portable terminal includes
unfolding/folding detecting means that determines which of the
first display region 9305 or the second display region 9306 is to
be used. The unfolding/folding detecting means includes a
protrusion 9313 provided for the first casing 9311, a hole 9314 and
control means 9315 provided for the second casing 9312, and the
like. In the folded state, the protrusion 9313 is in contact with
the control means 9315 disposed below the hole 9314. In this state,
the control means 9315 is set so that the ordinary display is
performed in the first display region 9305. On the other hand, in
the unfolded state, there is no protrusion 9313 being in contact
with the control means 9315. In this state, the control means 9315
is set so that the ordinary display is performed in the second
display region 9306. Note that the above-mentioned structure of the
unfolding/folding detecting means is just an example and is not
limited to the above description.
[0067] FIGS. 7A to 7C illustrate a digital camera, which includes a
first display region 9501 (hereinafter referred to as a display
region 9501), a second display region 9502 (hereinafter referred to
as a display region 9502), a lens 9503, and the like. The invention
is applicable to the display device including the display regions
9501 and 9502. FIG. 7B illustrates the state in which a panel
including the display regions 9501 and 9502 is closed, and FIGS. 7C
and 7D illustrate the opened state. In this digital camera, the
display region 9501 is used in the closed state, and one or both of
the display regions 9501 and 9502 are used in the opened state.
When the same images are displayed as the ordinary display in the
display regions 9501 and 9502 in the opened state, both a person
who takes a picture and a person of whom picture is taken can
simultaneously confirm the photography image (see FIG. 7C). In
addition, horizontally reversed display may be performed in the
display region 9501, and the ordinary display may be performed in
the display region 9502 (see FIG. 7D). Performing horizontally
reversed display in the display region 9501 in such a manner means
that the person of whom picture is taken confirms a mirror image.
In other words, the person of whom picture is taken can confirm its
mirror image which is usually confirmed by using a mirror and thus
can have a sense of comfort, and furthermore, it is possible to
groom its appearance by using the mirror image. This embodiment can
be arbitrarily combined with the above-mentioned embodiment mode
and embodiments.
Embodiment 5
[0068] The components of a display device of the present invention
and their relations are explained with reference to FIG. 8. As the
components of the display device of the invention, a panel 301
including a pixel portion 30, source drivers 15 and 16, and gate
drivers 27 and 28; a conversion circuit 304; and a controller 305
are given. The conversion circuit 304 controls which of a first
display region and a second display region disposed on the opposite
sides are to be used to perform the ordinary display. In addition,
if necessary, it controls to perform display selected from
horizontally reversed display, 180.degree. reversed display, and
vertically reversed display. The controller 305 controls the
operation of the panel 301.
[0069] An operation button 310, a volatile memory 312, a
nonvolatile memory 313, and an external interface 314 are given as
another components besides the above. These components are
controlled by a CPU (Central Processing Unit) 303. Data such as a
video signal is stored in the volatile memory 312 and nonvolatile
memory 313.
[0070] When the invention is applied to a foldable electronic
device, unfolding/folding detecting means 302 is provided as the
components besides the above. The unfolding/folding detecting means
302 detects the folded state and the unfolded state and supplies
the conversion circuit 304 with the information of the detection of
the folded and unfolded states. The conversion circuit 304 controls
which of a first display region and a second display region
disposed on the opposite sides are to be used to perform the
ordinary display based on the information supplied from the
unfolding/folding detecting means 302. In addition, when the
invention is applied to a cellular phone handset, a transmission
circuit 311, a microphone 307 which is a transmitter portion, a
speaker 308 which is a receiver portion, an audio controller 309,
and the like are provided as the components besides the above.
[0071] Note that the invention is not limited to the above
structure and may be equipped with other components. In addition,
this embodiment can be arbitrarily combined with the
above-mentioned embodiment mode and embodiments.
Embodiment 6
[0072] A display device of the present invention has a feature
having display regions on the opposite sides. When both of the
display regions on the opposite sides are used, the ordinary
display is preferably performed in one display region, and
horizontally reversed display is preferably performed in the other
display region (see FIG. 7C). In such a manner, both persons who
see a first display region and who see a second display region can
confirm the same image simultaneously. Accordingly, switching of
the display to be the ordinary display, the horizontally reversed
display, or the like is explained in this embodiment with reference
to FIGS. 9A to 9E.
[0073] As mentioned above, a panel includes a pixel portion 30
having (m.times.n) number of pixels, source drivers 15 and 16, and
gate drivers 27 and 28. Here, the source driver 15 and the gate
driver 27 are shown in the figure for simplicity to explain display
in a first display region with the use of a first sub-pixel (see
FIG. 9A).
[0074] A controller 305 determines a point where a start pulse is
supplied according to a signal supplied from a conversion circuit
304 or unfolding/folding detecting means 302. Specifically, S-SP1
is provided when a sub-pixel is selected from the first column,
S-SP2 is provided when a sub-pixel is selected from the m-th
column, G-SP1 is provided when a sub-pixel is selected from the
first row, and G-SP2 is provided when a sub-pixel is selected from
the n-th row.
[0075] Then, in the case of performing the ordinary display, start
pulses (S-SP1 and G-SP1) are supplied so that a sub-pixel arranged
in the first column and first row is selected first (see FIG. 9B).
In the case of performing horizontally reversed display, start
pulses (S-SP2 and G-SP1) are supplied so that a sub-pixel arranged
in the m-th column and the first row is selected first (see FIG.
9C). In the case of performing 180.degree. reversed display, start
pulses (S-SP2 and G-SP2) are supplied so that a sub-pixel arranged
in the m-th column and the n-th row is selected first (see FIG.
9D). In the case of performing vertically reversed display, start
pulses (S-SP1 and G-SP2) are supplied so that a sub-pixel arranged
in the first column and the n-th row is selected first (see FIG.
9E). In such a manner, a point where a start pulse is supplied is
changed depending on each display. In addition, the video signals
supplied to the sub-pixels from the source driver 15 are
appropriately changed.
[0076] Note that, in the case of applying a time gray scale method,
a video signal is loaded into a recording medium and then converted
into a video signal for a time gray scale as a method for
expressing a gray scale. Therefore, in the case of applying the
time gray scale method, the order of loading a video signal of the
ordinary display may be changed depending on the video signals for
displaying each of horizontally reversed display, 180.degree.
reversed display, and vertically reversed display, and these
display stored in a recording medium to correspond to each
display.
[0077] In addition, the switching of display may be performed
according to button operation by the user. In other words, the
direction of the ordinary display is set at an initial setup and,
if necessary, the direction of the display may be changed by the
user. In addition, in the case of a foldable electronic device, it
preferable to set at an initial setup so that the ordinary display
is performed in an internal display region in the unfolded state
and that the ordinary display is performed in an external display
region in the folded state.
[0078] In addition, an acceleration sensor that senses inclination
is provided, and a signal is supplied from the acceleration sensor.
Based on the supplied signal, which one of four sides of the
display region is the bottom is determined, and display may be
switched based on the decision. This embodiment can be arbitrarily
combined with the above-mentioned embodiment mode and
embodiments.
Embodiment 7
[0079] A light-emitting element, which is one of the components of
the present invention, corresponds to a lamination body of a first
conductive layer, an electroluminescent layer, and a second
conductive layer provided over a surface of a substrate having an
insulating surface such as glass, quartz, metal or an organic
matter, and having light-transmitting properties. The
light-emitting element may be any one of a lamination type in which
the electroluminescent layer is made from a plurality of layers, a
single-layer type in which the electroluminescent layer is made
from a single layer, or a mixed type in which the
electroluminescent layer is made from a plurality of layers of
which boundary is indefinite. In addition, as a laminated structure
of the light-emitting layer, there are a sequentially laminated
structure in which a conductive layer which corresponds to an
anode\an electroluminescent layer\a conductive layer which
corresponds to a cathode are laminated from the bottom, and a
reversely laminated structure in which a conductive layer which
corresponds to a cathode\an electroluminescent layer\a conductive
layer which corresponds to an anode are laminated from the bottom.
An appropriate structure may be selected depending on a
conductivity type of a TFT that drives the light-emitting element
or the direction of a current flown to the light-emitting element.
Any one of organic materials (low molecular, middle molecular, and
high molecular weight materials), inorganic materials, a singlet
material, a triplet material, or a material in which one or a
plurality of materials selected from the above four materials are
combined may be used for the electroluminescent layer. Light
emitted from the light-emitting element includes fluorescence and
phosphorescence, and either or both are used for the display device
of the invention. The light-emitting element provides a wide
viewing angle and realizes a small-size, thin-shaped, and
lightweight display device since a backlight is not necessary,
moreover, is applicable to moving image. A display device that
realizes sophistication and a high added value can be provided.
This embodiment can be arbitrarily combined with the
above-mentioned embodiment mode and embodiments.
[0080] This application is based on Japanese Patent Application
serial no. 2004-007387 filed in Japanese Patent Office on Jan. 14
2004, the contents of which are hereby incorporated by
reference.
* * * * *