Display device and method for operating the same

A display device that is driven with low power and a method for operating the display device are provided. The display device includes a host; a controller to which a first signal is supplied from the host; and a display panel to which a second signal is supplied from the controller. When the first signal includes image data, the first signal includes a command indicating the presence of the image data. When the controller detects the command, the controller supplies the image data as the second signal. When the controller does not detect the command, the controller stops supplying the second signal. After the controller stops supplying the second signal for a predetermined time, the controller resumes supplying the second signal regardless of whether or not the first signal includes the command.

TECHNICAL FIELD

One embodiment of the present invention relates to a display device and a method for operating the display device.

In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. In some cases, a display device, a light-emitting device, a memory device, an electro-optical device, a semiconductor circuit, and an electronic device include a semiconductor device.

BACKGROUND ART

Mobile industry processor interface (MIPI) standards, embedded DisplayPort (eDP), and other standards have been set for image data and control signals of display devices. In accordance with such a standard, communication is performed between a host (e.g., an application processor) and a timing controller (also called a display driver IC). Furthermore, panel self-refresh (PSR) technology has been proposed to reduce electric power required for communication.

A technique for using an oxide semiconductor transistor (hereinafter, referred to as an OS transistor) for a display device such as a liquid crystal display or an organic electroluminescence (EL) display has attracted attention. An OS transistor has an extremely low off-state current. In some disclosed techniques, by utilizing this fact, the refresh frequency at the time of displaying still images is reduced and power consumption of liquid crystal displays or organic EL displays is accordingly reduced (Patent Document 1 and Patent Document 2). Note that the aforementioned technique for reducing the power consumption of the display device is referred to as idling stop in this specification.

An example in which an OS transistor is used for a nonvolatile memory device has been disclosed in Patent Document 3, where the extremely low off-state current of the OS transistor is utilized.

REFERENCE

Patent Document

[Patent Document 1] Japanese Published Patent Application No. 2011-141522[Patent Document 2] Japanese Published Patent Application No. 2011-141524[Patent Document 3] Japanese Published Patent Application No. 2011-151383

DISCLOSURE OF INVENTION

To perform the above-mentioned idling stop, a dedicated circuit needs to be provided in a host that supplies a video signal. Accordingly, both a host and a panel need to be designed for idling stop to manufacture a display having an idling stop function.

An object of one embodiment of the present invention is to provide a display device that performs idling stop by a simple method and a method for operating the display device. Another object of one embodiment of the present invention is to provide a display device that performs idling stop at low costs and a method for operating the display device. Another object of one embodiment of the present invention is to provide a display device that is driven with low power consumption and a method for operating the display device. Another object of one embodiment of the present invention is to provide a novel semiconductor device.

Note that the description of a plurality of objects does not disturb the existence of each object. One embodiment of the present invention does not necessarily achieve all the objects. Objects other than those listed above are apparent from the description of the specification, drawings, claims, and the like and such objects could also be an object of one embodiment of the present invention.

One embodiment of the present invention is a display device that includes a host; a controller to which a first signal is supplied from the host; and a display panel to which a second signal is supplied from the controller. When the first signal includes image data, the first signal includes a command indicating the presence of the image data. When the controller detects the command, the controller supplies the image data as the second signal. When the controller does not detect the command, the controller stops supplying the second signal.

In the above embodiment, it is preferable that after the controller stops supplying the second signal for a predetermined time, the controller resume supplying the second signal regardless of whether or not the first signal includes the command.

In the above embodiment, the controller includes a frame memory, and the frame memory includes a transistor. The transistor preferably includes an oxide semiconductor in a channel formation region.

One embodiment of the present invention is a method for operating a display device that includes a host; a controller to which a first signal is supplied from the host; and a display panel to which a second signal is supplied from the controller. When the first signal includes image data, the first signal includes a command indicating the presence of the image data. When the controller detects the command, the controller supplies the image data as the second signal. When the controller does not detect the command, the controller stops supplying the second signal.

In the above embodiment, it is preferable that after the controller stops supplying the second signal for a predetermined time, the controller resume supplying the second signal regardless of whether or not the first signal includes the command.

In the above embodiment, the controller includes a frame memory, and the frame memory includes a transistor. The transistor preferably includes an oxide semiconductor in a channel formation region.

According to one embodiment of the present invention, a display device that performs idling stop by a simple method and a method for operating the display device can be provided. According to one embodiment of the present invention, a display device that performs idling stop at low costs and a method for operating the display device can be provided. According to one embodiment of the present invention, a display device that is driven with low power consumption and a method for operating the display device can be provided. According to one embodiment of the present invention, a novel semiconductor device can be provided.

Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily achieve all the effects listed above. Other effects will be apparent from and can be derived from the description of the specification, the drawings, the claims, and the like.

BEST MODE FOR CARRYING OUT THE INVENTION

In the drawings, the size, the layer thickness, or the region is exaggerated for clarity in some cases. Therefore, the size, the layer thickness, or the region is not limited to the illustrated scale. Note that the drawings are schematic views showing ideal examples, and embodiments of the present invention are not limited to shapes or values shown in the drawings.

Note that in this specification, a high power supply voltage and a low power supply voltage are sometimes referred to as an H level (or VDD) and an L level (or GND), respectively.

Furthermore, in the present specification, any of the embodiments described below can be combined as appropriate. In addition, in the case where a plurality of structure examples are described in one embodiment, some of the structure examples can be combined as appropriate.

In this embodiment, a display device of one embodiment of the present invention will be described.

<Configuration Example 1 of Display Device>

FIG. 1is a block diagram illustrating a configuration example of a display device1. The display device1includes a host10, a controller11, and a display panel12. The controller11includes a write circuit13, a frame memory14, a read circuit15, and a control circuit16. Note that the write circuit13, the read circuit15, and the control circuit16are closely related and there is sometimes no clear boundary between the circuits.

The host10includes a central processing unit (CPU) and has a function of supplying a signal21to the controller11. The signal21is a video signal and includes image data that is to be displayed by the display panel12.

The signal21is transmitted in a packet format. When the packet includes image data, the signal21has a specific format or a specific command. For example, in the case where the signal21conforms to a MIPI standard, examples of such a format and a command include packed pixel stream of Display Serial Interface (DSI) and write_memory_start of Display Command Set (DCS). Note that a general term “write command” is used to refer to such a format or a command in the present specification.

The write circuit13has a function of writing, into the frame memory14, image data received from the host10. In addition, the write circuit13has a function of decoding the write command included in the signal21.

The frame memory14is a memory for storing the image data that is supplied from the host10.

The read circuit15has a function of reading image data from the frame memory14. The read image data is supplied to the display panel12as a signal22.

The read circuit15has a function of controlling the display panel12. Specifically, the read circuit15outputs a clock signal or a start pulse signal to control the display panel12.

The control circuit16has a function of controlling idling stop of the display device1. Specifically, the control circuit16detects the write command that is decoded by the write circuit13, and determines operation of the read circuit15. When not detecting a write command, the control circuit16determines that the signal21is not supplied or the signal21does not include image data, and stops operation of the read circuit15. In that case, supply of the signal22is stopped. That is, the display device1goes into an idling stop state.

The display panel12includes a plurality of pixels and has a function of displaying the image data included in the signal22. The display panel12can display image data by control of emission/non-emission of the pixel. For the pixel, a liquid crystal element or an EL element (note that the EL element includes one or both of an organic compound and an inorganic compound) can be used, for example.

The pixel can include, in addition to them, at least one of an LED chip (e.g., a white LED chip, a red LED chip, a green LED chip, or a blue LED chip), a transistor (a transistor that emits light depending on current), an electron emitter, a display element including a carbon nanotube, electronic ink, an electrowetting element, an electrophoretic element, a display element using micro electro mechanical systems (MEMS) (such as a grating light valve (GLV), a digital micromirror device (DMD), a digital micro shutter (DMS), MIRASOL (registered trademark), an interferometric modulator display (IMOD) element, a MEMS shutter display element, an optical-interference-type MEMS display element, or a piezoelectric ceramic display element), quantum dots, and the like.

<Configuration Example 2 of Display Device>

The signal21supplied from the host10includes compressed image data in some cases. In that case, the controller11preferably includes a decoder.FIG. 2andFIG. 3each illustrate a configuration example of such a case.

A display device2illustrated inFIG. 2is different from the above display device1in that a decoder20is provided between the write circuit13and the frame memory14. The decoder20has a function of decompressing compressed image data.

The time it takes for the decoder20to decompress image data is long in many cases although it depends on the size of the image data. In the display device2, the image data stored in the frame memory14can be read by the read circuit15without passing through the decoder20. Thus, once image data is stored in the frame memory14, an image can be displayed by the display panel12in a short time.

<Configuration Example 3 of Display Device>

A display device3illustrated inFIG. 3is different from the above display devices1and2in that the decoder20is provided between the frame memory14and the read circuit15.

When image data has a large size, it is preferable that the frame memory14that stores the image data have a large memory capacity. However, a memory with a large capacity is expensive and increases the cost of the whole display device. In the display device3, image data in a compressed state can be stored in the frame memory14, so that the memory capacity of the frame memory14can be saved and the cost of the whole display device can be reduced.

<Operation Example 1 of Display Device>

Next, an operation example of the above-described display device will be described. Unless otherwise specified, the signal21conforms to a MIPI standard in the following description.

FIG. 4is a timing chart illustrating the signal21and the signal22. The timing chart inFIG. 4is divided into periods T1to T6to illustrate the timing of operation.

Each of the periods T1, T3, and T5is a retrace period of a video signal, and each of the periods T2and T6is one frame period of a video signal. The period T4is a period in which the display device is in an idling stop state.

In the period T1, a signal DI1is transmitted from the host10to the controller11. The control circuit16detects a write command included in the signal DI1. The control circuit16keeps receiving the signal DI1until the end of the period T2and finds out that image data in the frame memory14has been updated.

In the period T2, the image data written into the frame memory14is transmitted to the display panel12as a signal DO1, whereby an image on the display panel12is updated.

In the period T3, the signal21does not include image data. In other words, the control circuit16does not detect a write command. The control circuit16finds out that the image data in the frame memory14is not updated. The control circuit16stops operation of the read circuit15(idling stop). The operation of the read circuit15is stopped until the end of the period T4.

In the period T5, a signal DI3is transmitted from the host10to the controller11. The control circuit16detects a write command included in the signal DI3and resets the stop of the operation of the read circuit15. The control circuit16keeps receiving the signal DI3until the end of the period T6and finds out that the image data in the frame memory14has been updated.

In the period T6, the image data written into the frame memory14is transmitted to the display panel12as a signal DO3, whereby the image on the display panel12is updated.

For comparison, a timing chart (FIG. 25) of the case where the display device does not have an idling stop function is considered.FIG. 25is different fromFIG. 4in that a signal DO2is supplied in the period T4. Although the signal DO2appears to be one frame in the chart, the signal DO2is actually collection of frames.

In a display device without an idling stop function, an image on the display panel12needs to keep being updated even when supply of the signal21is suspended; therefore, image data stored in the frame memory14needs to be read at regular intervals to keep being supplied to the display panel. Consequently, the power consumption of the display device increases.

In the display device of one embodiment of the present invention, when supply of the signal21is stopped, operation of the read circuit15is stopped and supply of the signal22is also stopped as illustrated inFIG. 4. Consequently, the display device can consume less power.

In the display device of one embodiment of the present invention, the host10does not need to include a circuit dedicated to idling stop, so that idling stop can be performed by a simple method.

In another method for performing idling stop, a frame is observed in the controller11for a given time, and if there is no change, idling stop is performed. This method requires a large-scale image processing circuit in the controller11and thus increases the manufacturing cost of the controller11.

In the display device of one embodiment of the present invention, the controller11does not need to be provided with such a large-scale circuit and it is thus possible to manufacture the controller11at low costs.

<Operation Example 2 of Display Device>

When the display panel12is a liquid crystal panel, continuous application of a given potential to the liquid crystal by idling stop causes image burn-in on the liquid crystal panel. To prevent such image burn-in, the potential applied to the liquid crystal is preferably inverted at intervals of approximately one minute. It is thus preferable that the control circuit16include a timer and have a function of resetting idling stop after idling stop continues for a predetermined time (e.g., one minute). A timing chart of this case is shown inFIG. 5.

The period T4in the timing chart inFIG. 5is a period in which operation of the read circuit15is stopped. After a predetermined time passes as the period T4, the control circuit16resets the stop of operation of the read circuit15. Even when a write command is not detected from the signal21in the period T5, the read circuit15reads the image data that is stored in the frame memory14in the period T2and transmits the image data as the signal DO3.

In the case where the display device operates in accordance with the timing chart inFIG. 5, the decoder20is preferably provided between the write circuit13and the frame memory14as in the display device2illustrated inFIG. 2. In this manner, the read circuit15can read image data from the frame memory14in a short time.

<Operation Example 3 of Display Device>

The case where writing and reading of data into and from the frame memory14are performed in one frame period has been described with reference toFIG. 4andFIG. 5. Next, the case where data writing and data reading extend over a plurality of frame periods is described. A timing chart of this case is shown inFIG. 6.

First, the control circuit16detects a write command included in the signal DI1in the period T1. Then, in the period T2, writing of the signal DI1into the frame memory14starts. After a while after the wiring starts, the signal DO1is output.

In the period T3, the control circuit16does not detect a write command. In the period T4, the control circuit16stops the operation of the read circuit15after the output of the signal DO1ends.

Next, in the period T5, the control circuit16detects a write command included in the signal DI3and resets the stop of the read circuit15.

<Configuration Example of Packet>

FIG. 7illustrates an example of a packet format of the signal21(the case of a long packet format).

A packet is transferred between start of transmission (SoT) and end of transmission (EoT) and has a header area (a packet header) and a footer area (a packet footer).

Payload is a data area of a packet and includes the number of pixel gray levels, commands, information on pixel coordinate, or the like.

The header area includes data ID, the number of transferred data (a word count), and an error-correcting code (ECC).

The data ID includes a virtual channel identifier and information on the data type of the payload.

The above-mentioned write_memory_start is included in the payload. The above-mentioned packed pixel stream is included in the data ID.

A configuration of a memory cell that can be used for the frame memory14is described with reference toFIG. 8,FIGS. 9A and 9B,FIG. 10, andFIGS. 11A and 11B.

It is preferable that the frame memory14can perform writing and reading of image data at the same time. Two examples of the memory that can be used as the frame memory14are a dual-port memory and a single-port memory.

In this specification, a dual-port memory means a memory that performs data input and data output with a plurality of interfaces. The number of the interfaces is not limited to two and may be three or more. Since a dual-port memory has a plurality of interfaces, it can perform data writing and data reading at the same time.

In this specification, a single-port memory means a memory that performs data input and data output with a single interface. A single-port memory performs data writing and data reading at different timings. Note that a single-port memory can also perform data writing and data reading at the same time by utilizing double buffering technique or the like. A single-port memory includes a smaller number of wirings and transistors than a dual-port memory, so that the area occupied by a memory cell can be reduced.

First, an example of a dual-port memory is described.

<<Configuration Example 1 of Memory Cell>>

FIG. 8is a circuit diagram of a memory cell31that can be used for the frame memory14. The memory cell31is a typical static random access memory (SRAM). The memory cell31can include a transistor (a Si transistor) that includes Si in a channel formation region.

The memory cell31includes a wiring WW, a wiring RW, a wiring RB1, a wiring RB2, a wiring WB1, and a wiring WB2.

The wiring WW has a function of a word line for data writing, and the wiring RW has a function of a word line for data reading. The wirings WB1and WB2each have a function of a bit line for data writing. The wirings RB1and RB2each have a function of a bit line for data reading.

Separate wirings are provided as the bit line for data writing and the bit line for data reading in the memory cell31. Accordingly, a frame memory using the memory cell31is a dual-port memory.

<<Configuration Example 2 of Memory Cell>>

FIG. 9Ais a circuit diagram of a memory cell32that can be used for the frame memory14. The memory cell32includes a transistor M1, a transistor M2, a transistor M3, and a capacitor Cs1. The memory cell32is electrically connected to the wiring WW, the wiring RW, a wiring BG, the wiring RB1, the wiring WB1, and the wiring RB2.

The wiring WW has a function of a word line for data writing, and the wiring RW has a function of a word line for data reading. The wiring WB1has a function of a bit line for data writing. The wirings RB1and RB2each have a function of a bit line for data reading.

The transistor M1includes a first gate and a second gate. The first gate is electrically connected to the wiring WW and the second gate is electrically connected to the wiring BG. The first gate and the second gate preferably have regions overlapping with each other with a channel formation region positioned therebetween.

The transistor M1preferably has a low current (off-state current) flowing between a source and a drain in an off state. Here, the term “low off-state current” means that a normalized off-state current per micrometer of channel width with a voltage between a source and a drain set at 1.8 V is 1×10−20A or lower at room temperature, 1×10−18A or lower at 85° C., or 1×10−16A or lower at 125° C. An example of a transistor with such a low off-state current is an OS transistor.

Examples of oxide semiconductors that can be used for the above OS transistor include an In—Ga oxide, an In—Zn oxide, and an In-M-Zn oxide (M is Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf). Note that the oxide semiconductor is not limited to an oxide containing In. The oxide semiconductor may be, for example, a Zn oxide, a Zn—Sn oxide, or a Ga—Sn oxide.

Si transistors or OS transistors are preferably used as the transistors M2and M3.

Next, operation of the memory cell32is described. Note that an L level potential is applied to the wiring RB2during the operation.

First, the wiring WW is set at an H level to turn on the transistor M1. Data is written from the wiring WB1into a node FN1(a gate of the transistor M2) through the transistor M1.

Then, the wiring WW is set at an L level to turn off the transistor M1. Since the transistor M1has a low off-state current, the data written into the node FN1is retained for a long period of time.

Next, the wiring RB1is set at an H level and then, the wiring RB1is brought into an electrically floating state.

Next, an H level potential is applied to the wiring RW to turn on the transistor M3. Here, in the case where “1” has been written into the node FN1, the transistor M2is turned on, so that a current flows between the wiring RB1and the wiring RB2. In the case where “0” has been written into the node FN1, the transistor M2is turned off, so that a current does not flow between the wiring RB1and the wiring RB2. Finally, a change in potential of the wiring RB1is read, whereby the data written into the node FN can be read.

A predetermined potential VBGis preferably applied to the wiring BG. It is particularly preferable that a negative potential be applied as the potential VBG. When a negative potential is applied to the second gate of the transistor M1, the transistor M1can be prevented from being normally on. Note that the second gate of the transistor M1and the wiring BG need not be provided in some cases.

<<Configuration Example 3 of Memory Cell>>

FIG. 9Bis a circuit diagram of a memory cell33that can be used for the frame memory14. The memory cell33is different from the memory cell32in that p-channel transistors, a transistor M4and a transistor M5, are provided instead of the transistors M2and M3and that the capacitor Cs1is electrically connected to a wiring CL. An L level potential is constantly applied to the wiring CL.

Separate wirings are provided as the bit line for data writing and the bit line for data reading in each of the memory cells32and33as in the memory cell31. Accordingly, a frame memory using the memory cell32or the memory cell33is a dual-port memory.

The memory cell31is a volatile memory and thus, its data is lost when the power is turned off. In contrast, the memory cells32and33are nonvolatile and their data is not lost even after the power is turned off. As a result, the frame memory can save electric power. Specifically, the power can be turned off in the period T3and the period T4inFIG. 4, the period T3, the period T4, and the period T5inFIG. 5, and the period T4inFIG. 6.

Next, the case where the frame memory14is a single-port memory is described.

<<Configuration Example 4 of Memory Cell>>

FIG. 10is a circuit diagram of a memory cell34that can be used for the frame memory14. The circuit diagram of the memory cell34is obtained when a common bit line is used as the bit line for data writing and the bit line for data reading that are included in the memory cell31shown inFIG. 8.

A wiring WL has a function of a word line for data reading and data writing. A wiring BL1has a function of a bit line for data reading and data writing. Similarly, a wiring BL2has a function of a bit line for data reading and data writing.

The memory cell34has a smaller number of wirings and a smaller number of transistors than the memory cell31. Thus, the memory cell occupies a smaller area and a memory cell array having a high degree of integration can be built.

<<Configuration Example 5 of Memory Cell>>

FIG. 11Ais a circuit diagram of a memory cell35that can be used for the frame memory14. The memory cell35includes a transistor M6and a capacitor Cs2. The memory cell35is electrically connected to a wiring BL and the wiring WL.

The memory cell35is a typical dynamic random access memory (DRAM). A transistor (a Si transistor) containing silicon in a channel formation region can be used as the transistor M6.

The memory cell35has a smaller number of transistors than the memory cells31to34. Thus, the memory cell occupies a smaller area and a frame memory having a high degree of integration can be built.

<<Configuration Example 6 of Memory Cell>>

In the memory cell35, an OS transistor may be used as the transistor M6.FIG. 11Bis a circuit diagram of that case.

FIG. 11Bis a circuit diagram of a memory cell36that can be used for the frame memory14. The memory cell36includes a transistor M7and the capacitor Cs2. The transistor M7is preferably an OS transistor like the transistor M1shown inFIGS. 9A and 9B. When an OS transistor is used as the transistor M7, the data written into the capacitor Cs2can be retained for a long period of time in the memory cell36.

The transistor M7includes a first gate and a second gate. The first gate is electrically connected to the wiring WL and the second gate is electrically connected to the wiring BG. The first gate and the second gate preferably have regions overlapping with each other with a channel formation region positioned therebetween.

The predetermined potential VBGis preferably applied to the wiring BG. It is particularly preferable that a negative potential be applied as the potential VBG. When a negative potential is applied to the second gate of the transistor M7, the transistor M7can be prevented from being normally on. Note that the second gate of the transistor M7and the wiring BG need not be provided in some cases.

The memory cell35is a volatile memory and thus, its data is lost when the power is turned off. In contrast, the memory cell36is nonvolatile and its data is not lost even after the power is turned off. As a result, the frame memory can save electric power. Specifically, the power can be turned off in the period T3and the period T4inFIG. 4, the period T3, the period T4, and the period T5inFIG. 5, and the period T4inFIG. 6.

As described above, idling stop can be performed by a simple method with the use of the display device described in this embodiment and the method for operating the display device. In addition, idling stop can be performed at low costs. Furthermore, a display device that is driven with low power consumption and a method for operating the display device can be provided.

In this embodiment, a display device of one embodiment of the present invention will be described.

<Configuration Example of Display Device>

FIG. 12Ais a block diagram illustrating a configuration example of a display device4, andFIG. 12Bis a timing chart illustrating an example of operation of the display device4.

The display device4includes the host10, the controller11, and the display panel12. The controller11includes write circuits13aand13b, frame memories14aand14b, read circuits15aand15b, and a control circuit16a.

The write circuits13aand13beach correspond to the write circuit13shown inFIG. 1, the frame memories14aand14beach correspond to the frame memory14shown inFIG. 1, the read circuits15aand15beach correspond to the read circuit15shown inFIG. 1, and the control circuit16acorresponds to the control circuit16shown inFIG. 1. For details of other components of the display device4, the description ofFIG. 1can be referred to.

The host10supplies a signal21aand a signal21bto the controller11. The signal21ais a video signal and includes image data that is to be displayed by the display element30a. Similarly, the signal21bis a video signal and includes image data that is to be displayed by the display element30b.

In a manner similar to that of the signal21shown inFIG. 1, the signals21aand21bare transmitted in a packet format. When the packet includes image data, the signals21aand21binclude the write command described in Embodiment 1.

The write circuit13ahas a function of writing, into the frame memory14a, the image data included in the signal21a. The read circuit15ahas a function of reading the image data written into the frame memory14aand supplying the image data to the display panel12as a signal22a.

The write circuit13bhas a function of writing the image data included in the signal21binto the frame memory14b. The read circuit15bhas a function of reading the image data written into the frame memory14band supplying the image data to the display panel12as a signal22b.

The control circuit16adetects the write command that is decoded by the write circuit13a, and determines operation of the read circuit15a. When not detecting a write command, the control circuit16adetermines that the signal21ais not supplied or the signal21adoes not include image data, and stops operation of the read circuit15a. In that case, supply of the signal22ais stopped. That is, the display device4goes into an idling stop state.

<Operation Example of Display Device>

Next, operation of the display device4is described with reference to the timing chart inFIG. 12B. Note that in the following description, the signals21aand21bconform to a MIPI standard like the signal21.

In the period T1, a signal DI1aand a signal DI1bare transmitted from the host10to the controller11. The control circuit16adetects a write command included in the signal DI1a. The control circuit16akeeps receiving the signal DI1auntil the end of the period T2and finds out that image data in the frame memory14ahas been updated.

In the period T2, the image data written into the frame memory14ais transmitted to the display panel12as a signal DO1a, whereby the image displayed by the display element30ais updated. In a similar manner, the image data written into the frame memory14bis transmitted to the display panel12as a signal DO1b, whereby the image displayed by the display element30bis updated.

In the period T3, the signal21adoes not include image data. In other words, the control circuit16adoes not detect a write command. The control circuit16afinds out that the image data in the frame memory14ais not updated. The control circuit16astops operation of the read circuit15a. The operation of the read circuit15ais stopped until the end of the period T4. Note that the power of the frame memory14ais preferably turned off in the period T3and the period T4.

In the period T3, the signal21bdoes not include image data. In the period T4, the read circuit15breads the image data that is written in the period T2from the frame memory14b, and transmits the image data to the display panel12as a signal DO2b. Although the signal DO2bappears to be one frame in the chart, the signal DO2bis actually collection of frames.

In the period T5, a signal DI3aand a signal DI3bare transmitted from the host10to the controller11. The control circuit16adetects a write command included in the signal DI3aand resets the stop of the operation of the read circuit15a. The control circuit16akeeps receiving the signal DI3auntil the end of the period T6and finds out that the image data in the frame memory14ahas been updated.

In the period T6, the image data written into the frame memory14ais transmitted to the display panel12as a signal DO3a, whereby the image displayed by the display element30ais updated. In a similar manner, the image data written into the frame memory14bis transmitted to the display panel12as a signal DO3b, whereby the image displayed by the display element30bis updated.

Note that the control circuit16amay reset the stop of operation of the read circuit15abefore detecting a write command after operation of the read circuit15ais stopped for a predetermined time (e.g., one minute) as illustrated in the timing chart inFIG. 5.

The display device4illustrated inFIG. 12Aneed not be provided with the frame memory14bin some cases. In their words, the signal21binput to the controller11may be as it is when being output as the signal22b.

In the display device4illustrated inFIG. 12A, a decoder may be provided between the write circuit13aand the frame memory14a, between the frame memory14aand the read circuit15a, between the write circuit13band the frame memory14b, or between the frame memory14band the read circuit15b. In the case where a decoder is provided between the write circuit13aand the frame memory14aor between the write circuit13band the frame memory14b, the data in the frame memory can be read by the read circuit15aor15bin a short time without passing through a decoder, which is preferable. In the case where a decoder is provided between the frame memory14aand the read circuit15aor between the frame memory14band the read circuit15b, the frame memory14aor14bneeds a small memory capacity and the chip size of the controller11can be small, which is preferable.

As the display element30a, a reflective display element is preferably used. The use of a reflective display element can reduce power consumption. In addition, an image with high contrast can be favorably displayed in an environment with bright external light. Specifically, a reflective liquid crystal element can be used as the display element30a.

As the display element30b, a light-emitting element is preferably used. With the use of a light-emitting element, an image can be favorably displayed in a dark environment. Specifically, an organic EL element, an inorganic EL element, a light-emitting diode, or the like can be used as the display element30b.

In the display device4, when the display element30aand the display element30bare collected in one pixel, two images generated with separate display elements can be overlapped and displayed as one image.

For example, when a background image and a text image are selected as the signal21aand the signal21b, respectively, and these images are displayed overlapping with each other, the display device4can used as a book (e.g., a literary book, a textbook, or a picture book). For a background image, image data is not updated so often; thus, idling stop can be easily used for a background image. Therefore, a book with low power consumption can be obtained.

Furthermore, the display device4can be in three display modes: display by the display element30a, display by the display element30b, and display by the display elements30aand30b. The display device4can select any of these display modes in accordance with the brightness of external light. As a result, the display device4makes it possible to provide a display device having excellent viewability.

As described above, the use of the display device in this embodiment makes it possible to provide a low-power display device.

In this embodiment, details of the display panel12described in Embodiment 2 are described.

<Configuration Example of Display Panel>

FIG. 13is a block diagram illustrating a configuration example of the display panel12.

The display panel12includes a display region231. The display panel12can include a driver circuit GD or a driver circuit SD.

The display region231includes one group of pixels702(i,1) to702(i,n), another group of pixels702(1,j) to702(m,j), and a scan line G1(i). In addition, a scan line G2(i), a wiring CSCOM, a wiring ANO, and a signal line S2(j) are provided. Note that i is an integer greater than or equal to 1 and less than or equal to m, j is an integer greater than or equal to 1 and less than or equal to n, and each of m and n is an integer greater than or equal to 1.

The one group of pixels702(i,1) to702(i,n) include the pixel702(i,j) and are provided in the row direction (the direction indicated by the arrow R1in the drawing).

The another group of pixels702(1,j) to702(m,j) include the pixel702(i,j) and are provided in the column direction (the direction indicated by the arrow C1in the drawing) that intersects the row direction.

The scan line G1(i) and the scan line G2(i) are electrically connected to the one group of pixels702(i,1) to702(i,n) provided in the row direction.

The another group of pixels702(1,j) to702(m,j) provided in the column direction are electrically connected to a signal line S1(j) and the signal line S2(j).

The driver circuit GD has a function of supplying a selection signal in accordance with control data.

For example, the driver circuit GD has a function of supplying a selection signal to one scan line at a frequency of 30 Hz or higher, preferably 60 Hz or higher, in accordance with the control data. Accordingly, moving images can be smoothly displayed.

For example, the driver circuit GD has a function of supplying a selection signal to one scan line at a frequency lower than 30 Hz, preferably lower than 1 Hz, further preferably less than once per minute, in accordance with the control data. Accordingly, a still image can be displayed while flickering is suppressed.

The driver circuit SD includes a driver circuit SD1and a driver circuit SD2. The driver circuit SD1has a function of supplying an image signal in accordance with the signal22a. The driver circuit SD2has a function of supplying an image signal in accordance with the signal22b.

The driver circuit SD1has a function of generating an image signal that is to be supplied to a pixel circuit electrically connected to one display element. Specifically, the driver circuit SD1has a function of generating a signal whose polarity is inverted. With this configuration, for example, a liquid crystal display element can be driven.

The driver circuit SD2has a function of generating an image signal that is supplied to a pixel circuit electrically connected to another display element which displays an image by a method different from that of the one display element. With this configuration, for example, an organic EL element can be driven.

For example, a variety of sequential circuits, such as a shift register, can be used for the driver circuit SD.

For example, an integrated circuit in which the driver circuit SD1and the driver circuit SD2are integrated can be used for the driver circuit SD. Specifically, an integrated circuit formed over a silicon substrate can be used for the driver circuit SD.

The controller11may be included in the same integrated circuit as the driver circuit SD. Specifically, an integrated circuit formed over a silicon substrate can be used for each of the controller11and the driver circuit SD.

For example, the above integrated circuit can be mounted on a terminal by a chip on glass (COG) method or a chip on film (COF) method. Specifically, an anisotropic conductive film can be used to mount an integrated circuit on the terminal.

FIG. 14is a circuit diagram illustrating configuration examples of pixels702. The pixel702(i,j) has a function of driving a display element30a(i,j) and a display element30b(i,j). Accordingly, the display element30aand the display element30bwhich perform display using different methods can be driven with one pixel circuit, for example. Specifically, a reflective display element is used as the display element30a, whereby the power consumption can be reduced. Alternatively, an image with high contrast can be favorably displayed in an environment with bright external light. Alternatively, the display element30bwhich emits light is used, whereby an image can be favorably displayed in a dark environment.

The pixel702(i,j) is electrically connected to the signal line S1(j), the signal line S2(j), the scan line G1(i), the scan line G2(i), the wiring CSCOM, and the wiring ANO.

The pixel702(i,j) includes a switch SW1, a capacitor C11, a switch SW2, a transistor M, and a capacitor C12.

A transistor that includes a gate electrode electrically connected to the scan line G1(i) and a first electrode electrically connected to the signal line S1(j) can be used as the switch SW1.

The capacitor C11includes a first electrode electrically connected to a second electrode of the transistor used as the switch SW1and includes a second electrode electrically connected to the wiring CSCOM.

A transistor that includes a gate electrode electrically connected to the scan line G2(i) and a first electrode electrically connected to the signal line S2(j) can be used as the switch SW2.

The transistor M includes a gate electrode electrically connected to a second electrode of the transistor used as the switch SW2and includes a first electrode electrically connected to the wiring ANO.

Note that the transistor M may include a first gate electrode and a second gate electrode. The first gate electrode and the second gate electrode may be electrically connected to each other. The first gate electrode and the second gate electrode preferably have regions overlapping with each other with a semiconductor film positioned therebetween.

The capacitor C12includes a first electrode electrically connected to the second electrode of the transistor used as the switch SW2and includes a second electrode electrically connected to the first electrode of the transistor M.

A first electrode of the display element30a(i,j) is electrically connected to the second electrode of the transistor used as the switch SW1. A second electrode of the display element30a(i,j) is electrically connected to a wiring VCOM1. This enables the display element30a(i,j) to be driven.

A first electrode of the display element30b(i,j) is electrically connected to a second electrode of the transistor M. A second electrode of the display element30b(i,j) is electrically connected to a wiring VCOM2. This enables the display element30b(i,j) to be driven.

<Top View of Display Panel>

FIGS. 15A to 15Cillustrate a structure of the display panel12.FIG. 15Ais a top view of the display panel12, andFIG. 15Bis a top view illustrating part of a pixel of the display panel12inFIG. 15A.FIG. 15Cis a schematic view illustrating a structure of the pixel inFIG. 15B.

InFIG. 15A, the driver circuit SD and a terminal519B are provided over a flexible printed circuit FPC1.

InFIG. 15C, the pixel702(i,j) includes the display element30a(i,j) and the display element30b(i,j).

<Cross-sectional View of Display Panel>

FIGS. 16A and 16BandFIGS. 17A and 17Bare cross-sectional views illustrating a structure of the display panel12.FIG. 16Ais a cross-sectional view taken along lines X1-X2, X3-X4, and X5-X6inFIGS. 15A and 15B, andFIG. 16Billustrates part ofFIG. 16A.

Components of the display panel12are described below with reference toFIGS. 16A and 16BandFIGS. 17A and 17B.

The substrate570or the like can be formed using a material having heat resistance high enough to withstand heat treatment in the manufacturing process. For example, a material with a thickness greater than or equal to 0.1 mm and less than or equal to 0.7 mm can be used as the substrate570. Specifically, a material polished to a thickness of approximately 0.1 mm can be used.

For example, a large-sized glass substrate having any of the following sizes can be used as the substrate570or the like: the 6th generation (1500 mm×1850 mm), the 7th generation (1870 mm×2200 mm), the 8th generation (2200 mm×2400 mm), the 9th generation (2400 mm×2800 mm), and the 10th generation (2950 mm×3400 mm). Thus, a large-sized display device can be manufactured.

For the substrate570or the like, an organic material, an inorganic material, a composite material of an organic material and an inorganic material, or the like can be used. For example, an inorganic material such as glass, ceramic, or metal can be used for the substrate570or the like.

Specifically, non-alkali glass, soda-lime glass, potash glass, crystal glass, aluminosilicate glass, tempered glass, chemically tempered glass, quartz, sapphire, or the like can be used for the substrate570or the like. Specifically, an inorganic oxide film, an inorganic nitride film, an inorganic oxynitride film, or the like can be used for the substrate570or the like. For example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxide film, or the like can be used for the substrate570or the like. Stainless steel, aluminum, or the like can be used for the substrate570or the like.

For example, a single crystal semiconductor substrate or a polycrystalline semiconductor substrate of silicon or silicon carbide, a compound semiconductor substrate of silicon germanium or the like, an SOI substrate, or the like can be used as the substrate570or the like. Thus, a semiconductor element can be provided over the substrate570or the like.

For example, an organic material such as a resin, a resin film, or plastic can be used for the substrate570or the like. Specifically, a resin film or a resin plate of polyester, polyolefin, polyamide, polyimide, polycarbonate, an acrylic resin, or the like can be used for the substrate570or the like.

For example, a composite material formed by attaching a metal plate, a thin glass plate, or a film of an inorganic material to a resin film or the like can be used for the substrate570or the like. For example, a composite material formed by dispersing a fibrous or particulate metal, glass, an inorganic material, or the like into a resin film can be used for the substrate570or the like. For example, a composite material formed by dispersing a fibrous or particulate resin, an organic material, or the like into an inorganic material can be used for the substrate570or the like.

Furthermore, a single-layer material or a layered material in which a plurality of layers are stacked can be used for the substrate570or the like. For example, a layered material in which a base, an insulating film that prevents diffusion of impurities contained in the base, and the like are stacked can be used for the substrate570or the like. Specifically, a layered material in which glass and one or a plurality of films that are selected from a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, and the like and that prevent diffusion of impurities contained in the glass are stacked can be used for the substrate570or the like. Alternatively, a layered material in which a resin and a film for preventing diffusion of impurities that penetrate the resin, such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film, are stacked can be used for the substrate570or the like.

Specifically, a resin film, a resin plate, a layered material, or the like of polyester, polyolefin, polyamide, polyimide, polycarbonate, an acrylic resin, or the like can be used for the substrate570or the like.

Specifically, a material including polyester, polyolefin, polyamide (e.g., nylon or aramid), polyimide, polycarbonate, polyurethane, an acrylic resin, an epoxy resin, or a resin having a siloxane bond, such as silicone, can be used for the substrate570or the like.

Specifically, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), an acrylic resin, or the like can be used for the substrate570or the like. Alternatively, a cyclo-olefin polymer (COP), a cyclo-olefin copolymer (COC), or the like can be used.

Alternatively, paper, wood, or the like can be used for the substrate570or the like.

For example, a flexible substrate can be used as the substrate570or the like.

Note that a transistor, a capacitor, or the like can be directly formed on the substrate. Alternatively, a transistor, a capacitor, or the like formed over a substrate for use in manufacturing processes which can withstand heat applied in the manufacturing process can be transferred to the substrate570or the like. Accordingly, a transistor, a capacitor, or the like can be formed over a flexible substrate, for example.

For example, a light-transmitting material can be used for the substrate770. Specifically, any of the materials that can be used for the substrate570can be used for the substrate770.

For example, aluminosilicate glass, tempered glass, chemically tempered glass, sapphire, or the like can be favorably used for the substrate770that is provided on the user side of the display panel. This can prevent damage or a crack of the display panel caused by the use thereof.

Moreover, a material having a thickness greater than or equal to 0.1 mm and less than or equal to 0.7 mm, for example, can be used for the substrate770. Specifically, a substrate polished for reducing the thickness can be used. Thus, a functional film770D can be located so as to be close to the display element30a(i,j). As a result, image blur can be reduced and an image can be displayed clearly.

For example, an organic material, an inorganic material, or a composite material of an organic material and an inorganic material can be used for a structure body KB1or the like. Accordingly, a predetermined space can be provided between components between which the structure body KB1and the like are provided.

Specifically, for the structure body KB1, polyester, polyolefin, polyamide, polyimide, polycarbonate, polysiloxane, an acrylic resin, or the like, or a composite material of a plurality of resins selected from these can be used. Alternatively, a photosensitive material may be used.

For a sealant705or the like, an inorganic material, an organic material, a composite material of an inorganic material and an organic material, or the like can be used.

For example, an organic material such as a thermally fusible resin or a curable resin can be used for the sealant705or the like.

For example, an organic material such as a reactive curable adhesive, a photo-curable adhesive, a thermosetting adhesive, and/or an anaerobic adhesive can be used for the sealant705or the like.

Specifically, an adhesive containing an epoxy resin, an acrylic resin, a silicone resin, a phenol resin, a polyimide resin, an imide resin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB) resin, an ethylene vinyl acetate (EVA) resin, or the like can be used for the sealant705or the like.

For example, any of the materials that can be used for the sealant705can be used for a bonding layer505.

For example, an insulating inorganic material, an insulating organic material, or an insulating composite material containing an inorganic material and an organic material can be used for insulating films521and518and the like.

Specifically, an inorganic oxide film, an inorganic nitride film, an inorganic oxynitride film, or a layered material obtained by stacking some of these films can be used as the insulating films521and518and the like. For example, a film including any of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxide film, and the like, or a film including a material obtained by stacking some of these films can be used as the insulating films521and518and the like.

Specifically, for the insulating films521and518and the like, polyester, polyolefin, polyimide, polyimide, polycarbonate, polysiloxane, an acrylic resin, or the like, or a layered or composite material of a plurality of kinds of resins selected from these can be used. Alternatively, a photosensitive material may be used.

Thus, steps due to various components overlapping with the insulating films521and518, for example, can be reduced.

For example, any of the materials that can be used for the insulating film521can be used for an insulating film528or the like. Specifically, a 1-μm-thick polyimide-containing film can be used as the insulating film528.

For example, any of the materials that can be used for the insulating film521can be used for an insulating film501A. For example, a material having a function of supplying hydrogen can be used for the insulating film501A.

Specifically, a material obtained by stacking a material containing silicon and oxygen and a material containing silicon and nitrogen can be used for the insulating film501A. For example, a material having a function of releasing hydrogen by heating or the like to supply the hydrogen to another component can be used for the insulating film501A. Specifically, a material having a function of releasing hydrogen taken in the manufacturing process, by heating or the like, to supply the hydrogen to another component can be used for the insulating film501A.

For example, a film containing silicon and oxygen that is formed by a chemical vapor deposition method using silane or the like as a source gas can be used as the insulating film501A.

Specifically, a material obtained by stacking a material containing silicon and oxygen and having a thickness greater than or equal to 200 nm and less than or equal to 600 nm and a material containing silicon and nitrogen and having a thickness of approximately 200 nm can be used for the insulating film501A.

For example, any of the materials that can be used for the insulating film521can be used for an insulating film501C. Specifically, a material containing silicon and oxygen can be used for the insulating film501C. Thus, impurity diffusion into the pixel circuit or the display element30b(i,j) can be suppressed.

For example, a 200-nm-thick film containing silicon, oxygen, and nitrogen can be used as the insulating film501C.

For example, a film with a thickness greater than or equal to 10 nm and less than or equal to 500 nm, preferably greater than or equal to 10 nm and less than or equal to 100 nm can be used as an intermediate film754A, an intermediate film754B, or an intermediate film754C.

In this specification, the intermediate film754A, the intermediate film754B, or the intermediate film754C is referred to as an intermediate film.

For example, a material having a function of allowing the passage of hydrogen or the supply of hydrogen can be used for the intermediate film.

For example, a conductive material can be used for the intermediate film.

For example, a light-transmitting material can be used for the intermediate film.

Specifically, a material containing indium and oxygen, a material containing indium, gallium, zinc, and oxygen, a material containing indium, tin, and oxygen, or the like can be used for the intermediate film. Note that these materials have a function of allowing the passage of hydrogen.

Specifically, a 50- or 100-nm-thick film containing indium, gallium, zinc, and oxygen can be used as the intermediate film.

Note that a material obtained by stacking films serving as an etching stopper can be used as the intermediate film. Specifically, a layered material obtained by stacking a 50-nm-thick film containing indium, gallium, zinc, and oxygen and a 20-nm-thick film containing indium, tin, and oxygen, in this order, can be used for the intermediate film.

A conductive material can be used for a wiring or the like. Specifically, the conductive material can be used for the signal line S1(j), the signal line S2(j), the scan line G1(i), the scan line G2(i), the wiring CSCOM, the wiring ANO, the terminal519B, a terminal519C, a conductive film511B, a conductive film511C, or the like.

For example, an inorganic conductive material, an organic conductive material, a metal material, a conductive ceramic material, or the like can be used for the wiring or the like.

Specifically, a metal element selected from aluminum, gold, platinum, silver, copper, chromium, tantalum, titanium, molybdenum, tungsten, nickel, iron, cobalt, palladium, and manganese, or the like can be used for the wiring or the like. Alternatively, an alloy including any of the above-described metal elements, or the like can be used for the wiring or the like. In particular, an alloy of copper and manganese is suitably used in microfabrication with use of a wet etching method.

Specifically, a two-layer structure in which a titanium film is stacked over an aluminum film, a two-layer structure in which a titanium film is stacked over a titanium nitride film, a two-layer structure in which a tungsten film is stacked over a titanium nitride film, a two-layer structure in which a tungsten film is stacked over a tantalum nitride film or a tungsten nitride film, a three-layer structure in which a titanium film, an aluminum film, and a titanium film are stacked in this order, or the like can be used for the wiring or the like.

Specifically, a conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium is added can be used for the wiring or the like.

Specifically, a film containing graphene or graphite can be used for the wiring or the like.

For example, a film including graphene oxide is formed and is reduced, so that a film including graphene can be formed. As a reducing method, a method using heat, a method using a reducing agent, or the like can be employed.

For example, a film including a metal nanowire can be used for the wiring or the like. Specifically, a nanowire including silver can be used.

Specifically, a conductive polymer can be used for the wiring or the like.

Note that the terminal519B can be electrically connected to a flexible printed circuit FPC1using a conductive material ACF1, for example.

For example, a display element having a function of controlling transmission or reflection of light can be used as the display element30a(i,j). For example, a combined structure of a liquid crystal element and a polarizing plate or a MEMS shutter display element can be used. Specifically, a reflective liquid crystal display element can be used as the display element30a(i,j). The use of a reflective display element can reduce the power consumption of a display panel.

For example, a liquid crystal element that can be driven by any of the following driving methods can be used: an in-plane switching (IPS) mode, a twisted nematic (TN) mode, a fringe field switching (FFS) mode, an axially symmetric aligned micro-cell (ASM) mode, an optically compensated birefringence (OCB) mode, a ferroelectric liquid crystal (FLC) mode, an antiferroelectric liquid crystal (AFLC) mode, and the like.

In addition, a liquid crystal element that can be driven by, for example, a vertical alignment (VA) mode such as a multi-domain vertical alignment (MVA) mode, a patterned vertical alignment (PVA) mode, an electrically controlled birefringence (ECB) mode, a continuous pinwheel alignment (CPA) mode, or an advanced super view (ASV) mode can be used.

The display element30a(i,j) includes an electrode751(i,j), an electrode752, and a layer753containing a liquid crystal material. The layer753contains a liquid crystal material whose alignment is controlled by a voltage applied between the electrode751(i,j) and the electrode752. For example, the alignment of the liquid crystal material can be controlled by an electric field in the thickness direction (also referred to as the vertical direction) of the layer753or the direction that crosses the vertical direction (the horizontal direction, or the diagonal direction).

For example, thermotropic liquid crystal, low-molecular liquid crystal, high-molecular liquid crystal, polymer dispersed liquid crystal, ferroelectric liquid crystal, anti-ferroelectric liquid crystal, or the like can be used for the layer753. A liquid crystal material that exhibits a cholesteric phase, a smectic phase, a cubic phase, a chiral nematic phase, an isotropic phase, or the like can be used. Alternatively, a liquid crystal material that exhibits a blue phase can be used.

For example, the material that is used for the wiring or the like can be used for the electrode751(i,j). Specifically, a reflective film can be used for the electrode751(i,j). For example, a material in which a light-transmitting conductive film and a reflective film having an opening are stacked can be used for the electrode751(i,j).

For example, a conductive material can be used for the electrode752. For example, a material having a visible-light-transmitting property can be used for the electrode752.

For example, a conductive oxide, a metal film thin enough to transmit light, or a metal nanowire can be used for the electrode752.

Specifically, a conductive oxide containing indium can be used for the electrode752. Alternatively, a metal thin film with a thickness greater than or equal to 1 nm and less than or equal to 10 nm can be used for the electrode752. Alternatively, a metal nanowire containing silver can be used for the electrode752.

Specifically, indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide to which gallium is added, zinc oxide to which aluminum is added, or the like can be used for the electrode752.

For example, a material reflecting visible light can be used for the reflective film. Specifically, a material containing silver can be used for the reflective film. For example, a material containing silver, palladium, and the like or a material containing silver, copper, and the like can be used for the reflective film.

The reflective film reflects light that passes through the layer753, for example. This allows the display element30a(i,j) to serve as a reflective liquid crystal element. Alternatively, a material with an uneven surface can be used for the reflective film. In that case, incident light can be reflected in various directions so that a white image can be displayed.

For example, the electrode751(i,j) or the like can be used as the reflective film.

For example, the reflective film can be provided as a film that includes a region sandwiched between the layer753and the electrode751(i,j). In the case where the electrode751(i,j) has a light-transmitting property, the reflective film can be provided as a film that includes a region overlapping with the layer753with the electrode751(i,j) positioned between the film and the layer753.

The reflective film preferably includes a region that does not block light emitted from the display element30b(i,j), for example. The reflective film preferably has a shape with one or more openings751H, for example.

The opening may have a polygonal shape, a quadrangular shape, an elliptical shape, a circular shape, a cross-like shape, or the like. The opening751H may also have a stripe shape, a slit-like shape, or a checkered pattern.

If the ratio of the total area of the opening751H to the total area except for the openings is too high, display performed using the display element30a(i,j) is dark.

If the ratio of the total area of the opening751H to the total area except for the openings is too low, display performed using the display element30b(i,j) is dark.

FIGS. 18A to 18Care schematic views each illustrating the shape of the reflective film that can be used in the pixel of the display panel12.

The opening751H of the pixel702(i,j+1), which is adjacent to the pixel702(i,j), is not provided on a line that extends in the row direction (the direction indicated by the arrow R1in each ofFIGS. 18A to 18C) through the opening751H of the pixel702(i,j) (seeFIG. 18A). Alternatively, for example, the opening751H of the pixel702(i+1,j), which is adjacent to the pixel702(i,j), is not provided on a line that extends in the column direction (the direction indicated by the arrow C1in each ofFIGS. 18A to 18C) through the opening751H of the pixel702(i,j) (seeFIG. 18B).

For example, the opening751H of the pixel702(i,j+2) is provided on a line that extends in the row direction through the opening751H of the pixel702(i,j) (seeFIG. 18A). In addition, the opening751H of the pixel702(i,j+1) is provided on a line that is perpendicular to the above-mentioned line between the opening751H of the pixel702(i,j) and the opening751H of the pixel702(i,j+2).

Alternatively, for example, the opening751H of the pixel702(i+2,j) is provided on a line that extends in the column direction through the opening751H of the pixel702(i,j) (seeFIG. 18B). In addition, for example, the opening751H of the pixel702(i+1,j) is provided on a line that is perpendicular to the above-mentioned line between the opening751H of the pixel702(i,j) and the opening751H of the pixel702(i+2,j).

Thus, the display element30bthat includes a region overlapping with an opening of a pixel adjacent to one pixel can be apart from the display element30bthat includes a region overlapping with an opening of the one pixel. Furthermore, a display element that exhibits color different from that exhibited by the display element30bof the one pixel can be provided as the display element30bof the pixel adjacent to the one pixel. Furthermore, the difficulty in adjacently arranging a plurality of display elements that exhibit different colors can be lowered.

For example, the reflective film can be formed using a material having a shape in which an end portion is cut off so as to form a region751E that does not block light emitted from the display element30b(i,j) (seeFIG. 18C). Specifically, the electrode751(i,j) whose end portion is cut off so as to be shorter in the column direction (the direction indicated by the arrow C1in the drawing) can be used as the reflective film.

For example, the alignment films AF1and AF2can be formed with a material containing polyimide or the like. Specifically, a material formed by rubbing treatment or an optical alignment technique so that a liquid crystal material has alignment in a predetermined direction can be used.

For example, a film containing soluble polyimide can be used as the alignment film AF1or AF2. In this case, the temperature required in forming the alignment film AF1or AF2can be low. Accordingly, damage to other components at the time of forming the alignment film AF1or AF2can be suppressed.

A material transmitting light of a predetermined color can be used for the coloring film CF1or the coloring film CF2. Thus, the coloring film CF1or the coloring film CF2can be used as a color filter, for example. For example, a material that transmits blue light, green light, or red light can be used for the coloring film CF1or the coloring film CF2. Furthermore, a material that transmits yellow light, white light, or the like can be used for the coloring film CF1or the coloring film CF2.

Note that a material having a function of converting the emitted light to a predetermined color light can be used for the coloring film CF2. Specifically, quantum dots can be used for the coloring film CF2. Thus, display with high color purity can be achieved.

A material that prevents light transmission can be used for the light-blocking film BM. Thus, the light-blocking film BM can be used as, for example, a black matrix.

The insulating film771can be formed of polyimide, an epoxy resin, or an acrylic resin, for example.

For example, an anti-reflection film, a polarizing film, a retardation film, a light diffusion film, a condensing film, or the like can be used as a functional film770P or the functional film770D.

Specifically, a film containing a dichromatic pigment can be used as the functional film770P or the functional film770D. Furthermore, a material having a pillar-shaped structure with an axis in a direction that intersects a surface of the substrate can be used for the functional film770P or the functional film770D. This makes it easy to transmit light in a direction along the axis and to scatter light in the other directions.

Alternatively, an antistatic film inhibiting the attachment of a foreign substance, a water repellent film inhibiting the attachment of stain, a hard coat film inhibiting a scratch in use, or the like can be used as the functional film770P.

Specifically, a circularly polarizing film can be used as the functional film770P. Furthermore, a light diffusion film can be used as the functional film770D.

For example, the display element30b(i,j) can be a light-emitting element. Specifically, an organic electroluminescent element, an inorganic electroluminescent element, a light-emitting diode, or the like can be used as the display element30b(i,j).

The display element30b(i,j) includes an electrode551(i,j), an electrode552, and a layer553(j) containing a light-emitting material.

For example, a light-emitting organic compound can be used for the layer553(j).

For example, quantum dots can be used for the layer553(j). Accordingly, the half width becomes narrow, and light of a bright color can be emitted.

For example, a layered material for emitting blue light, green light, or red light, or the like can be used for the layer553(j).

For example, a belt-like layered material that extends in the column direction along the signal line S2(j) can be used for the layer553(j).

Alternatively, a layered material for emitting white light can be used for the layer553(j). Specifically, a layered material in which a layer including a fluorescent material that emits blue light, and a layer containing materials that are other than a fluorescent material and that emit green light and red light or a layer containing a material that is other than a fluorescent material and that emits yellow light are stacked can be used for the layer553(j).

For example, a material that can be used for the wiring or the like can be used for the electrode551(i,j).

For example, a material that transmits visible light selected from materials that can be used for the wiring or the like can be used for the electrode551(i,j).

Specifically, conductive oxide, indium-containing conductive oxide, indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide to which gallium is added, or the like can be used for the electrode551(i,j). Alternatively, a metal film that is thin enough to transmit light can be used as the electrode551(i,j). Further alternatively, a metal film that transmits part of light and reflects another part of light can be used as the electrode551(i,j). Thus, the display element30b(i,j) can be provided with a microcavity structure. Consequently, light of a predetermined wavelength can be extracted more efficiently than light of the other wavelengths.

For example, a material that can be used for the wiring or the like can be used for the electrode552. Specifically, a material that reflects visible light can be used for the electrode552.

Any of a variety of sequential circuits, such as a shift register, can be used as the driver circuit GD. For example, a transistor MD, a capacitor, and the like can be used in the driver circuit GD. Specifically, a transistor including a semiconductor film that can be formed in the same process as the transistor M or the transistor which can be used as the switch SW1can be used.

As the transistor MD, a transistor having a different structure from the transistor that can be used as the switch SW1can be used, for example. Specifically, a transistor including a conductive film524can be used as the transistor MD.

Note that the transistor MD can have the same structure as the transistor M.

For example, semiconductor films formed at the same step can be used for transistors in the driver circuit and the pixel circuit.

For example, a bottom-gate transistor, a top-gate transistor, or the like can be used for transistors in a driver circuit or a pixel circuit.

For example, the OS transistor described in Embodiment 1 can be used. In that case, the above-mentioned idling stop can be performed.

For example, a transistor including an oxide semiconductor film508, a conductive film504, a conductive film512A, and a conductive film512B can be used as the switch SW1(seeFIG. 17B). Note that an insulating film506includes a region sandwiched between the oxide semiconductor film508and the conductive film504.

The conductive film504includes a region overlapping with the oxide semiconductor film508. The conductive film504has a function of a gate electrode. The insulating film506has a function of a gate insulating film.

The conductive film512A and the conductive film512B are electrically connected to the oxide semiconductor film508. The conductive film512A has one of a function of a source electrode and a function of a drain electrode, and the conductive film512B has the other.

A transistor including the conductive film524can be used as the transistor in the driver circuit or the pixel circuit. The conductive film524includes a region so that the oxide semiconductor film508is sandwiched between the conductive film504and the region. Note that the insulating film516includes a region sandwiched between the conductive film524and the oxide semiconductor film508. For example, the conductive film524is electrically connected to a wiring that supplies the same potential as that supplied to the conductive film504.

A conductive film in which a 10-nm-thick film containing tantalum and nitrogen and a 300-nm-thick film containing copper are stacked in this order can be used as the conductive film504, for example. Note that the film containing copper includes a region so that the film containing tantalum and nitrogen is sandwiched between the region and the insulating film506.

A material in which a 400-nm-thick film containing silicon and nitrogen and a 200-nm-thick film containing silicon, oxygen, and nitrogen are stacked can be used for the insulating film506, for example. Note that the film containing silicon and nitrogen includes a region so that the film containing silicon, oxygen, and nitrogen is sandwiched between the region and the oxide semiconductor film508.

A 25-nm-thick film containing indium, gallium, and zinc can be used as the oxide semiconductor film508, for example.

A conductive film in which a 50-nm-thick film containing tungsten, a 400-nm-thick film containing aluminum, and a 100-nm-thick film containing titanium are stacked in this order can be used as the conductive film512A or the conductive film512B, for example. Note that the film containing tungsten includes a region in contact with the oxide semiconductor film508.

This embodiment can be combined with any other embodiment as appropriate.

FIG. 19Ais a bottom view illustrating part of the pixel of the display panel illustrated inFIG. 15B.FIG. 19Bis a bottom view illustrating the part of the structure illustrated inFIG. 19Ain which some components are omitted.

In this embodiment, an input/output panel is described in which a touch panel is included in the display device described in any of the above embodiments.

FIG. 20is a block diagram illustrating the configuration of an input/output panel250that includes a touch panel240and the display panel12.FIG. 21Ais a top view of the input/output panel250.FIG. 21Bis a schematic view illustrating part of an input portion of the input/output panel250.

The touch panel240includes a sensor region241, an oscillator circuit OSC, and a sensor circuit DC (seeFIG. 20).

The sensor region241includes a region overlapping with the display region231of the display panel12. The sensor region241has a function of sensing an object approaching the region overlapping with the display region231.

The sensor region241includes one group of sensor elements775(g,1) to775(g,q) and another group of sensor elements775(1,h) to775(p,h). Note that g is an integer greater than or equal to 1 and less than or equal to p, h is an integer greater than or equal to 1 and less than or equal to q, and p and q are each an integer greater than or equal to 1.

The one group of sensor elements775(g,1) to775(g,q) include the sensor element775(g,h) and are arranged in a row direction (indicated by the arrow R2in the drawing).

The another group of sensor elements775(1,h) to775(p,h) include the sensor element775(g,h) and are provided in the column direction (the direction indicated by the arrow C2in the drawing) that intersects the row direction.

The one group of sensor elements775(g,1) to775(g,q) provided in the row direction include an electrode SE(g) that is electrically connected to a control line SL(g) (seeFIG. 21B).

The another group of sensor elements775(1,h) to775(p,h) provided in the column direction include an electrode ME(h) that is electrically connected to a sensor signal line ML(h) (seeFIG. 21B).

The electrode SE(g) and the electrode ME(h) preferably have a light-transmitting property.

Note that the control line SL(g) has a function of supplying a control signal.

The sensor signal line ML(h) has a function of receiving a sensor signal.

The electrode ME(h) is placed to form an electric field between the electrode ME(h) and the electrode SE(g). When an object such as a finger approaches the sensor region241, the above electric field is blocked and the sensor element775(g,h) supplies the sensor signal.

The oscillator circuit OSC is electrically connected to the control line SL(g) and has a function of supplying a control signal. For example, a rectangular wave, a sawtooth wave, a triangular wave, or the like can be used for the control signal.

The sensor circuit DC is electrically connected to the sensor signal line ML(h) and has a function of supplying a sensor signal P1on the basis of a change in the potential of the sensor signal line ML(h). Note that the sensor signal P1includes positional data, for example.

The sensor signal P1is supplied to the host10. The host10supplies the signals21aand21bin response to the sensor signal P1, so that the image displayed by the display region231is updated.

FIGS. 22A and 22BandFIG. 23illustrate a structure of the input/output panel250.FIG. 22Ais a cross-sectional view taken along lines X1-X2, X3-X4, and X5-X6inFIG. 21A.FIG. 22Bis a cross-sectional view illustrating part of the structure illustrated inFIG. 22A.

The input/output panel250is different from, for example, the display panel12described in Embodiment 3 in that the input/output panel250includes a functional layer720and a top-gate transistor. Here, the different portions will be described in detail, and the above description is referred to for the other similar portions.

The functional layer720includes a region surrounded by the substrate770, the insulating film501C, and the sealant705(FIGS. 22A and 22B).

The functional layer720includes the control line SL(g), the sensor signal line ML(h), and the sensor element775(g,h).

The gap between the control line SL(g) and the second electrode752or between the sensor signal line ML(h) and the second electrode752is greater than or equal to 0.2 μm and less than or equal to 16 μm, preferably greater than or equal to 1 μm and less than or equal to 8 μm, further preferably greater than or equal to 2.5 μm and less than or equal to 4 μm.

Note that the conductive material CP or the like can be provided between the control line SL(g) and the conductive film511D to electrically connect the control line SL(g) and the conductive film511D. Alternatively, the conductive material CP or the like can be provided between the sensor signal line ML(h) and the conductive film511D to electrically connect the sensor signal line ML(h) and the conductive film511D. A material that can be used for the wiring or the like can be used for the conductive film511D, for example.

The input/output panel250includes a terminal519D (seeFIG. 23). The terminal519D is electrically connected to the conductive film511D.

The terminal519D is provided with the conductive film511D and an intermediate film754D, and the intermediate film754D includes a region in contact with the conductive film511D.

A material that can be used for the wiring or the like can be used for the terminal519D, for example. Specifically, the terminal519D can have the same structure as the terminal519B or the terminal519C.

Note that the terminal519D can be electrically connected to the flexible printed circuit FPC2using a conductive material ACF2, for example. Thus, a control signal can be supplied to the control line SL(g) with use of the terminal519D, for example. Alternatively, a sensor signal can be supplied from the sensor signal line ML(h) with use of the terminal519D.

A transistor that can be used as the switch SW1, the transistor M, and the transistor MD each include the conductive film504having a region overlapping with the insulating film501C and the oxide semiconductor film508having a region sandwiched between the insulating film501C and the conductive film504. Note that the conductive film504functions as a gate electrode (seeFIG. 22B).

The oxide semiconductor film508includes a first region508A, a second region508B, and a third region508C. The first region508A and the second region508B do not overlap with the conductive film504. The third region508C is positioned between the first region508A and the second region508B and overlaps with the conductive film504.

The transistor MD includes the insulating film506between the third region508C and the conductive film504. Note that the insulating film506functions as a gate insulating film.

The first region508A and the second region508B have a lower resistivity than the third region508C, and function as a source region and a drain region.

For example, an oxide semiconductor film is subjected to plasma treatment using a gas including a rare gas, so that the first region508A and the second region508B can be formed in the oxide semiconductor film508.

For example, the conductive film504can be used for a mask. Thus, part of the third region508C can be formed into a shape of an end of the conductive film504in a self-aligned manner.

The transistor MD includes the conductive film512A and the conductive fihn512B that are in contact with the first region508A and the second region508B, respectively. The conductive film512A and the conductive film512B function as a source electrode and a drain electrode.

A transistor that can be fabricated in the same process as the transistor MD can be used as the transistor M, for example.

In this embodiment, electronic devices including the display device of one embodiment of the present invention will be described with reference toFIGS. 24A to 24H.

FIG. 24Aillustrates a mobile computer that can include a switch5009, an infrared port5010, and the like in addition to the above components.FIG. 24Billustrates a portable image reproducing device (e.g., a DVD reproducing device) provided with a recording medium, and the portable image reproducing device can include a second display portion5002, a recording medium reading portion5011, and the like in addition to the above components.FIG. 24Cillustrates a goggle-type display that can include the second display portion5002, a support portion5012, an earphone5013, and the like in addition to the above components.FIG. 24Dillustrates a portable game console that can include the recording medium reading portion5011and the like in addition to the above components.FIG. 24Eillustrates a digital camera with a television reception function, and the digital camera can include an antenna5014, a shutter button5015, an image receiving portion5016, and the like in addition to the above components.FIG. 24Fillustrates a portable game console that can include the second display portion5002, the recording medium reading portion5011, and the like in addition to the above components.FIG. 24Gillustrates a portable television receiver that can include a charger5017capable of transmitting and receiving signals, and the like in addition to the above components.

The electronic devices illustrated inFIGS. 24A to 24Gcan have a variety of functions such as a function of displaying a variety of data (a still image, a moving image, a text image, and the like) on the display portion, a touch panel function, a function of displaying a calendar, the date, the time, and the like, a function of controlling processing with a variety of software (programs), a wireless communication function, a function of being connected to a variety of computer networks with a wireless communication function, a function of transmitting and receiving a variety of data with a wireless communication function, and a function of reading a program or data stored in a recording medium and displaying the program or data on the display portion. Furthermore, the electronic device including a plurality of display portions can have a function of displaying image data mainly on one display portion while displaying text data mainly on another display portion, a function of displaying a three-dimensional image by displaying images on a plurality of display portions with a parallax taken into account, or the like. Furthermore, the electronic device including an image receiving portion can have a function of shooting a still image, a function of taking moving images, a function of automatically or manually correcting a shot image, a function of storing a shot image in a recording medium (an external recording medium or a recording medium incorporated in the camera), a function of displaying a shot image on the display portion, or the like. Note that functions of the electronic devices inFIGS. 24A to 24Gare not limited thereto, and the electronic devices can have a variety of functions.

FIG. 24Hillustrates a smart watch, which includes a housing7302, a display panel7304, operation buttons7311and7312, a connection terminal7313, a band7321, a clasp7322, and the like.

The display panel7304mounted in the housing7302serving as a bezel includes a non-rectangular display region. The display panel7304may have a rectangular display region. The display panel7304can display an icon7305indicating time, another icon7306, and the like.

The smart watch inFIG. 24Hcan have a variety of functions such as a function of displaying a variety of data (e.g., a still image, a moving image, and a text image) on the display portion, a touch panel function, a function of displaying a calendar, date, time, and the like, a function of controlling processing with a variety of software (programs), a wireless communication function, a function of being connected to a variety of computer networks with a wireless communication function, a function of transmitting and receiving a variety of data with a wireless communication function, and a function of reading out a program or data stored in a recording medium and displaying it on the display portion.

The housing7302can include a speaker, a sensor (a sensor having a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotational frequency, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electric power, radiation, flow rate, humidity, gradient, oscillation, odor, or infrared rays), a microphone, and the like. Note that the smart watch can be manufactured using a light-emitting element for the display panel7304.

Unless otherwise specified, an on-state current in this specification refers to a drain current of a transistor in an on state. Unless otherwise specified, the on state of an n-channel transistor means that the voltage (VG) between its gate and source is higher than or equal to the threshold voltage (Vth), and the on state of a p-channel transistor means that VGis lower than or equal to Vth. For example, the on-state current of an n-channel transistor refers to a drain current that flows when VGis higher than or equal to Vth. The on-state current of a transistor sometimes depends on a voltage (VD) between a drain and a source.

Unless otherwise specified, an off-state current in this specification refers to a drain current of a transistor in an off state. Unless otherwise specified, the off state of an n-channel transistor means that VGis lower than Vth, and the off state of a p-channel transistor means that VGis higher than Vth. For example, the off-state current of an n-channel transistor refers to a drain current that flows when VGis lower than Vth. The off-state current of a transistor depends on VGin some cases. Thus, “the off-state current of a transistor is lower than 10−21A” may mean there is VGat which the off-state current of the transistor is lower than 10−21A.

The off-state current of a transistor depends on VDin some cases. Unless otherwise specified, the off-state current in this specification may be an off-state current at VDwith an absolute value of 0.1 V, 0.8 V, 1 V, 1.2 V, 1.8 V, 2.5 V, 3 V, 3.3 V, 10 V, 12 V, 16 V, or 20 V. Alternatively, the off-state current may be an off-state current at VDused in a semiconductor device or the like including the transistor.

In this specification and the like, the terms “one of a source and a drain” (or a first electrode or a first terminal) and “the other of the source and the drain” (or a second electrode or a second terminal) are used to describe the connection relation of a transistor. This is because a source and a drain of a transistor are interchangeable depending on the structure, operation conditions, or the like of the transistor. Note that the source or the drain of the transistor can also be referred to as a source (or drain) terminal, a source (or drain) electrode, or the like as appropriate depending on the situation.

For example, in this specification and the like, an explicit description “X and Y are connected” means that X and Y are electrically connected, X and Y are functionally connected, and X and Y are directly connected. Accordingly, without being limited to a predetermined connection relationship, for example, a connection relationship shown in drawings or texts, another connection relationship is included in the drawings or the texts.

Here, each of X and Y denotes an object (e.g., a device, an element, a circuit, a wiring, an electrode, a terminal, a conductive film, or a layer).

Examples of the case where X and Y are directly connected include the case where an element that enables electrical connection between X and Y (e.g., a switch, a transistor, a capacitor, an inductor, a resistor, a diode, a display element, a light-emitting element, or a load) is not connected between X and Y, and the case where X and Y are connected without the element that enables electrical connection between X and Y provided therebetween.

Note that in this specification and the like, an explicit description “X and Y are electrically connected” means that X and Y are electrically connected (i.e., the case where X and Y are connected with another element or another circuit provided therebetween), X and Y are functionally connected (i.e., the case where X and Y are functionally connected with another circuit provided therebetween), and X and Y are directly connected (i.e., the case where X and Y are connected without another element or another circuit provided therebetween). That is, in this specification and the like, the explicit description “X and Y are electrically connected” is the same as the explicit description “X and Y are connected”.

For example, any of the following expressions can be used for the case where a source (or a first terminal or the like) of a transistor is electrically connected to X through (or not through) Z1and a drain (or a second terminal or the like) of the transistor is electrically connected to Y through (or not through) Z2, or the case where a source (or a first terminal or the like) of a transistor is directly connected to one part of Z1and another part of Z1is directly connected to X while a drain (or a second terminal or the like) of the transistor is directly connected to one part of Z2and another part of Z2is directly connected to Y.

Other examples of the expressions include, “a source (or a first terminal or the like) of a transistor is electrically connected to X through at least a first connection path, the first connection path does not include a second connection path, the second connection path is a path between the source (or the first terminal or the like) of the transistor and a drain (or a second terminal or the like) of the transistor, Z1is on the first connection path, the drain (or the second terminal or the like) of the transistor is electrically connected to Y through at least a third connection path, the third connection path does not include the second connection path, and Z2is on the third connection path” and “a source (or a first terminal or the like) of a transistor is electrically connected to X at least with a first connection path through Z1, the first connection path does not include a second connection path, the second connection path includes a connection path through which the transistor is provided, a drain (or a second terminal or the like) of the transistor is electrically connected to Y at least with a third connection path through Z2, and the third connection path does not include the second connection path”. Still another example of the expression is “a source (or a first terminal or the like) of a transistor is electrically connected to X through at least Z1on a first electrical path, the first electrical path does not include a second electrical path, the second electrical path is an electrical path from the source (or the first terminal or the like) of the transistor to a drain (or a second terminal or the like) of the transistor, the drain (or the second terminal or the like) of the transistor is electrically connected to Y through at least Z2on a third electrical path, the third electrical path does not include a fourth electrical path, and the fourth electrical path is an electrical path from the drain (or the second terminal or the like) of the transistor to the source (or the first terminal or the like) of the transistor”. When the connection path in a circuit configuration is defined by an expression similar to the above examples, a source (or a first terminal or the like) and a drain (or a second terminal or the like) of a transistor can be distinguished from each other to specify the technical scope.

Note that these expressions are examples and there is no limitation on the expressions. Here, X, Y, Z1, and Z2each denote an object (e.g., a device, an element, a circuit, a wiring, an electrode, a terminal, a conductive film, or a layer).

Even when independent components are electrically connected to each other in a circuit diagram, one component has functions of a plurality of components in some cases. For example, when part of a wiring also functions as an electrode, one conductive film functions as the wiring and the electrode. Thus, the term “electrical connection” in this specification also means such a case where one conductive film has functions of a plurality of components.

REFERENCE NUMERALS

This application is based on Japanese Patent Application serial no. 2016-098455 filed with Japan Patent Office on May 17, 2016, the entire contents of which are hereby incorporated by reference.