Showing papers by "Jun Koyama published in 2012"
01 Jun 2012
TL;DR: Kimizuka et al. as discussed by the authors found crystalline IGZO having c-axis alignment and have studied its application to displays, memories, processors, etc., which is expected to be used in a variety of applications.
Abstract: The study of IGZO was started by Kimizuka et al. in 1985. IGZO is developed as a material for displays. We found crystalline IGZO having c-axis alignment and have studied its application to displays, memories, processors, etc. Crystalline IGZO is expected to be used in a variety of applications.
188 citations
TL;DR: In this article, the authors measured a significantly low off-state current (135 yA/µm at 85 °C) of a metal oxide semiconductor (MOS) transistor using indium-gallium-zinc oxide (IGZO), which is an oxide material.
Abstract: We measured a significantly low off-state current (135 yA/µm at 85 °C) of a metal oxide semiconductor (MOS) transistor using indium–gallium–zinc oxide (IGZO), which is an oxide semiconductor material. Note that "y" is 10-24. A transistor in which the hydrogen concentration in an IGZO film is lowered (5×1019 cm-3 or lower) was used. To estimate the minute current accurately, we established a measurement method in which changes in the amount of electrical charge are measured for a long time. Such extremely low off-state current characteristics show promise for new applications of IGZO transistors in memories.
87 citations
Patent•
26 Oct 2012
TL;DR: In this paper, a pixel TFT formed in a pixel region is formed on a first substrate by a channel etch type reverse stagger type TFT, and patterning of a source region and a drain region, and patterns of a pixel electrode are performed by the same photomask.
Abstract: A pixel TFT formed in a pixel region is formed on a first substrate by a channel etch type reverse stagger type TFT, and patterning of a source region and a drain region, and patterning of a pixel electrode are performed by the same photomask. A driver circuit formed by using TFTs having a crystalline semiconductor layer, and an input-output terminal dependent on the driver circuit, are taken as one unit. A plurality of units are formed on a third substrate, and afterward the third substrate is partitioned into individual units, and the obtained stick drivers are mounted on the first substrate.
58 citations
01 Jun 2012
TL;DR: A 5Tr+1C threshold voltage compensation pixel circuit that operates even with a normally‐on transistor, which has a top‐emission structure using white tandem OLEDs with color filters.
Abstract: We devised a 5Tr+1C threshold voltage compensation pixel circuit that operates even with a normally-on transistor. Variations in threshold voltage can be reduced to 25 to 30%. We fabricated a 13.5-inch quad full high definition (QFHD) OLED display, which has a top-emission structure using white tandem OLEDs with color filters.
40 citations
20 May 2012
TL;DR: A dynamic random access memory (DRAM) using crystalline oxide semiconductor (OS) transistors and not requiring refresh for more than ten days is fabricated.
Abstract: We fabricated a dynamic random access memory (DRAM) using crystalline oxide semiconductor (OS) transistors and not requiring refresh for more than ten days. We call this memory a dynamic oxide semiconductor random access memory (DOSRAM). A crystalline oxide semiconductor is an In-Ga-Zn-oxide (IGZO) semiconductor and has a c-axis aligned crystal (CAAC) structure. A crystalline OS transistor has extremely low off-state current. The DOSRAM uses this device for access transistors, and can have a very long refresh cycle. A memory cell array made of a crystalline OS layer can be stacked on peripheral circuits made of a silicon (Si) semiconductor layer; thus, the area of the DOSRAM can be decreased.
35 citations
TL;DR: A novel field-sequential AMLCD integrated with a scan driver by combining the liquid-crystal-display (LCD) technology using blue phase and oxide-semiconductor technology has been developed.
Abstract: — Through the realization of a blue-phase-mode (hereinafter, the operational mode of liquid crystal having a blue phase is referred to as a blue-phase mode), a display using an improved field-sequential method was confirmed to be capable of display at a frame rate of 180 fps (field frequency of 540 Hz) or higher. Under this condition, an image without annoyance caused by color breakup was obtained. Moreover, a novel field-sequential AMLCD integrated with a scan driver by combining the liquid-crystal-display (LCD) technology using blue phase and oxide-semiconductor technology has been developed.
22 citations
01 Jun 2012
TL;DR: In this paper, a low-power display technology of liquid crystal display (LCD) including crystalline IGZO by variable frame frequency has been previously reported and application of the technology to controller and processor unit as well as the LCD and the driver(s) proposes a method for saving power of the whole display system.
Abstract: The low-power display technology of liquid crystal display (LCD) including crystalline IGZO by variable frame frequency has been previously reported. Application of the technology to controller and processor unit as well as the LCD and the driver(s) proposes a method for saving power of the whole display system.
20 citations
Patent•
05 Oct 2012
TL;DR: In this paper, a first transistor is provided in a substrate including a semiconductor material and the second transistor includes an oxide semiconductor layer, and the first transistor has a first gate electrode, a first source electrode, and a first drain electrode.
Abstract: An object is to provide a semiconductor device with a novel structure. The semiconductor device includes a first wiring; a second wiring; a third wiring; a fourth wiring; a first transistor having a first gate electrode, a first source electrode, and a first drain electrode; and a second transistor having a second gate electrode, a second source electrode, and a second drain electrode. The first transistor is provided in a substrate including a semiconductor material. The second transistor includes an oxide semiconductor layer.
19 citations
14 citations
Patent•
02 Nov 2012
TL;DR: A display device is manufactured with five photolithography steps: a gate electrode, a step of forming a protective layer for reducing damage due to an etching step or the like as discussed by the authors.
Abstract: A display device is manufactured with five photolithography steps: a step of forming a gate electrode, a step of forming a protective layer for reducing damage due to an etching step or the like, a step of forming a source electrode and a drain electrode, a step of forming a contact hole, and a step of forming a pixel electrode. The display device includes a groove portion which is formed in the step of forming the contact hole and separates the semiconductor layer.
10 citations
01 Jun 2012
TL;DR: In this paper, a prototype of a 3.4-inch polymer-stabilized blue-phase display was made, which includes a highly reliable crystalline oxide semiconductor and operates favorably.
Abstract: We achieved low-voltage driving of a blue-phase liquid crystal display by employing liquid crystal with high dielectric anisotropy and a chiral material with high helical twisting power. A prototype of a 3.4-inch polymer-stabilized blue-phase display was made, which includes a highly reliable crystalline oxide semiconductor and operates favorably.
Patent•
29 Nov 2012
TL;DR: In this paper, a memory circuit including a transistor having a semiconductor layer containing an oxide semiconductor is used as a memory that stores a lookup table for correcting image signals in accordance with a change in the external environment.
Abstract: A display device driver circuit in which a lookup table can be written into a memory circuit within a retrace period even when the lookup table is constantly reconstructed in accordance with a change in the external environment and stored in the memory circuit, and data of the lookup table can be held even if supply of power supply voltage stops. In a driver circuit for a display device, a memory circuit including a transistor having a semiconductor layer containing an oxide semiconductor is used as a memory circuit that stores a lookup table for correcting image signals in accordance with a change in the external environment.
Patent•
22 Mar 2012
TL;DR: An image processing method to obtain a high sense of depth or high stereoscopic effect for an image and a display device utilizing the method are provided in this paper, where the relative distance between the viewer's eye and any of the objects is determined by the data of the sizes of objects in the image and the sizes stored in the database, so that an object with a shorter relative distance is enlarged.
Abstract: An image processing method to obtain a high sense of depth or high stereoscopic effect for an image and a display device utilizing the method are provided. Image data of an image is separated into image data of a plurality of objects and a background. A feature amount is obtained from the image data of each object, so that the objects are identified. The relative distance between viewer's eye and any of the objects is determined by the data of the sizes of the objects in the image and the sizes of the objects stored in the database. The image data of each object is processed so that an object with a shorter relative distance is enlarged. The image data of each object after image processing is combined with the image data of the background, so that a sense of depth or stereoscopic effect of an image is increased.
Patent•
27 Aug 2012
TL;DR: In this article, the authors proposed a nonvolatile latch circuit with a data holding section and a switching element using an oxide semiconductor as a semiconductor material constituting a channel formation region and an inverter electrically connected to a source electrode or a drain electrode of the transistor.
Abstract: PROBLEM TO BE SOLVED: To provide a novel nonvolatile latch circuit and a semiconductor device therewith.SOLUTION: The nonvolatile latch circuit includes a latch section and a data holding section. The latch section has a loop structure in which an output of a first element is electrically connected to an input of a second element, and an output of the second element is electrically connected to an input of the first element. The data holding section holds data in the latch section. The data holding section uses as a switching element a transistor using an oxide semiconductor as a semiconductor material constituting a channel formation region. There is also an inverter electrically connected to a source electrode or a drain electrode of the transistor. The transistor can be used to write the data held in the latch section to a gate capacitance of the inverter or to a separately prepared capacitance.
01 Jun 2012
TL;DR: In this article, a 3D panel was fabricated by combining an OLED display and a liquid crystal parallax barrier including a driver using a crystalline oxide semiconductor in a backplane.
Abstract: We fabricated a 3D panel by combining an OLED display and a liquid crystal parallax barrier including a driver using a crystalline oxide semiconductor in a backplane. The combination with a supersonic sensor for detecting the positions of the user and the panel can correct the position of the barrier.
Patent•
26 Apr 2012
TL;DR: In this article, the same step of photolithography step and etching step was used to reduce the photolithographic step and to provide a liquid crystal display device with low power consumption and high reliability.
Abstract: PROBLEM TO BE SOLVED: To provide a liquid crystal display device with low cost and high productivity by remarkably reducing manufacturing steps and provide a liquid crystal display device with low power consumption and high reliabilitySOLUTION: Etching of a semiconductor layer including a part on gate wiring and formation of a contact hole for connecting a pixel electrode and a drain electrode are performed by the same step of photolithography step and etching step to reduce the photolithography step A part of the gate wiring exposed by this step is covered by an insulating layer, which is made to double as spacer for maintaining an interval between liquid crystal layers By reducing the photolithography step, it is possible to provide a liquid crystal display device with low cost and high productivity Further, since an oxide semiconductor is used for the semiconductor layer, power consumption is reduced and the liquid crystal display device with high reliability can be provided
Patent•
10 Jul 2012
TL;DR: In this article, the parallax barrier is used to suppress crosstalk between a display and a non-light-emitting region between the first display region and the second display region.
Abstract: An object is to suppress crosstalk A display device includes a pixel portion which includes a first display region, a second display region, and a non-light-emitting region provided between the first display region and the second display region; and a parallax barrier which includes a first light control region, a second light control region, and a light-transmitting region provided between the first light control region and the second light control region The first light control region overlaps with the first display region, the second light control region overlaps with the second display region, and the center of the width of the light-transmitting region overlaps with the non-light-emitting region
Patent•
30 Oct 2012
TL;DR: In this paper, a liquid crystal display unit is manufactured without increase of the number of photomasks, skipping a photolithography step and an etching step for forming an island-shaped semiconductor layer.
Abstract: PROBLEM TO BE SOLVED: To provide a display unit having a transistor with enhanced reliability, without increase of the number of photomasks for use in a manufacturing process.SOLUTION: A display unit is manufactured without increase of the number of photomasks, skipping a photolithography step and an etching step for forming an island-shaped semiconductor layer. Specifically, a liquid crystal display unit is manufactured through the five photolithography steps of: forming a gate electrode; forming a protective layer for reducing damage in the steps of forming a gate electrode, etching, and the like; forming a source electrode and a drain electrode; forming a contact hole, and forming a pixel electrode. The liquid crystal display unit in one embodiment includes a groove part for dividing a semiconductor layer, which is concurrently formed in the step of forming the contact hole.
Patent•
03 Oct 2012
TL;DR: In this article, the brightness of an image to be displayed in a pixel portion is determined according to the contrast of the image to determine whether to be inverted or not, and the number of bits of the digital video signal to be input into the pixel portion was reduced.
Abstract: The present invention is intended to suppress power consumption of an EL display. In accordance with the brightness of an image to be displayed in a pixel portion, the contrast of the image is determined whether to be inverted or not, and the number of bits of the digital video signal to be input into the pixel portion is reduced, and the magnitude of a current to flow through the EL element is allowed to be maintained at a constant level even when a temperature of an EL layer changes by providing the EL display with another EL element to be used for monitoring a temperature.
Patent•
01 Jun 2012
TL;DR: In this paper, a flexible substrate is bent with conductive films inside, so that the conductive film separately provided on the right and left of a bend line can be electrically connected.
Abstract: PROBLEM TO BE SOLVED: To provide a semiconductor device typified by a wireless tag, which can be formed through a simpler process, have higher mechanical strength while suppressing cost, and prevent block of electric waves.SOLUTION: A flexible substrate is bent with conductive films inside, so that the conductive films separately provided on the right and left of a bend line can be electrically connected. Thus, the function as an antenna can be achieved.
Patent•
29 May 2012
TL;DR: In this paper, a plurality of storage circuits are arranged in a pixel and a digital video signals are stored for each pixel, so that when a still picture is displayed, at least one frame of signals are processed and then a source signal line driving circuit can be stopped thereafter, and with this, power consumption can greatly reduce.
Abstract: PROBLEM TO BE SOLVED: To suppress power consumption of a portable information device.SOLUTION: A plurality of storage circuits are arranged in a pixel and a digital video signals are stored for each pixel. When a still picture is displayed, the picture is written once and then information written to the pixel is the same, so the still picture can continuously be displayed by reading the signals stored in the storage circuits without inputting signals for each frame. Namely, when the still picture is displayed, at least one frame of signals are processed and then a source signal line driving circuit can be stopped thereafter, and with this, power consumption can greatly be reduced.
Patent•
16 Jan 2012
TL;DR: In this article, a phase inverting element that inverts and outputs a phase of an input signal is used to suppress power consumption without requiring a complicated manufacturing process and a signal processing circuit using the memory device.
Abstract: An object is to provide a memory device that can suppress power consumption without requiring a complicated manufacturing process and a signal processing circuit using the memory device. In a storage element using a phase inverting element that inverts and outputs a phase of an input signal, such as an inverter or a clocked inverter, a capacitor element for holding data, and a charge in the capacitor element And a switching element for controlling the accumulation and release of. As the switching element, a transistor including an oxide semiconductor in a channel formation region is used. The memory element is used for a memory device such as a register or a cache memory included in the signal processing circuit. [Selection] Figure 1
Patent•
25 Jun 2012
TL;DR: In this article, the authors proposed a liquid crystal display with a switching transistor, a driving circuit part, and a pixel circuit part including a pixel transistor and a plurality of pixels.
Abstract: PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying a moving image and a still image, in which malfunction is suppressed and lower power consumption is possible.SOLUTION: A liquid crystal display device includes: a first substrate provided with a terminal part, a switching transistor, a driving circuit part, and a pixel circuit part including a pixel transistor and a plurality of pixels; a second substrate provided with a common electrode electrically connected to the terminal part via the switching transistor; and liquid crystal held between a pixel electrode and the common electrode. In a period of displaying a still image, a first terminal and a second terminal of the switching transistor are set in a non-conductive state and the common electrode is set in an electrically floating state. In a period where the still image is switched to a moving image, a first step of supplying a common potential to the common electrode, a second step of supplying a power supply voltage to the driving circuit part, a third step of supplying a clock signal to the driving circuit part, and a fourth step of supplying a start pulse signal to the driving circuit part are sequentially performed.
04 Sep 2012
TL;DR: In this paper, the authors discuss the effect of phase change memory (PCM) on the performance of ReRAM (Resistance RAM) and Phase Change Memory(PCM).
Abstract: 近年ノーマリオフコンピューティング技術が注目されて いる[1]。ノーマリオフコンピューティング技術は、コンピ ュータの揮発性メモリを不揮発性メモリで置き換え、パワ ーゲーティングと不揮発性メモリを効率的に制御すること で、プロセッサが処理を行っていない期間は積極的に電源 を遮断し、高速での電源復帰を行う、電力の無駄を排除し た低消費電力技術である。図 1 に、プロセッサのメモリの 階層構造を示す[2]。プロセッサのメモリは、性能、面積、 電力等の観点から階層構造をとっている。図 1 の揮発性メ モリを不揮発性メモリに置き換えるには、不揮発性メモリ に、アクセス速度、実質無限大の書き換え耐性、低電力動 作などが要求される。不揮発性メモリは、フラッシュメモ リの置き換えを狙い、ReRAM (Resistance RAM) [3]、PCM (Phase Change Memory) [4]などが開発されているが、まだ 課題があり、ノーマリオフコンピュータに応用できる不揮 発性メモリは開発途上といえる。
Patent•
09 Feb 2012
TL;DR: In this article, an optimal parallax barrier is formed as appropriate by selectively switching a lighttransmitting state and a light-shielding state of a plurality of optical shutter regions and a display element unit of pixels depending on a retention state.
Abstract: To extend the range of distance (between a display screen and the eye of a viewer) with which the viewer can see 3D images with the naked eye and to reduce power consumption. A parallax barrier in a shutter panel is controlled to be arranged optimally in accordance with the distance between the viewer and a display panel. Specifically, an optimal parallax barrier is formed as appropriate by selectively switching a light-transmitting state and a light-shielding state of a plurality of optical shutter regions and a display element unit of pixels depending on a retention state. The retention state is realized in such a manner that at least one of electrodes between which a liquid crystal layer is sandwiched is connected to a transistor including a semiconductor layer containing an oxide semiconductor and the transistor is turned off.
Patent•
05 Dec 2012
TL;DR: In this paper, a display device includes a display panel and a shutter panel including a first liquid crystal element and a second liquid crystal elements that are adjacent to each other and provided on the visible side of the display panel.
Abstract: PROBLEM TO BE SOLVED: To increase a distance range that allows three-dimensional display for naked eyes of a viewer, where the distance means a distance between a display screen and the eyes of the viewer.SOLUTION: A display device includes a display panel and a shutter panel including a first liquid crystal element and a second liquid crystal element that are adjacent to each other and provided on the visible side of the display panel. In a first display state, a first light-blocking region and a first light-transmitting region are formed on the shutter panel by the first liquid crystal element, and the light from the display panel is released from the first light-transmitting region. In a second display state, a second light-blocking region which is larger than the first light-blocking region, and a second light-transmitting region which is smaller than the first light-transmitting region, are formed on the shutter panel by the first liquid crystal element and the second liquid crystal element, and the light from the display panel is released from the second light-transmitting region.SELECTED DRAWING: Figure 1
Patent•
15 Mar 2012
TL;DR: In this paper, an EL element is electrically connected to the current control TFT and an LDD region is provided for the current-control TFT so as to overlap with a gate electrode with gate insulation film interposed there.
Abstract: PROBLEM TO BE SOLVED: To provide an electronic device capable of displaying a bright image, a highly reliable electronic device, and to provide a process for reducing the manufacturing cost of the electronic device capable of displaying an image with high luminanceSOLUTION: In a pixel structure including a switching TFT and a current control TFT, an EL element is electrically connected to the current control TFT An LDD region is provided for the current control TFT so as to overlap with a gate electrode with a gate insulation film interposed therebetween, and this can provide a pixel with a large effective light emission area in which the voltage applied to the gate electrode is held by a gate capacitance between the gate electrode and the LDD region