Patents by Inventor Tokuro Ozawa
Tokuro Ozawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6965366Abstract: An electro-optical driving device for providing a high-quality display that is free from non-uniformities. Subpixels 120a, 120b, and 120c are arranged at the respective intersections of 3m scanning lines 112 that extend in the X direction and n data lines 114 that extend in the Y direction. The subpixels 120a, 120b, and 120c are adjacent in the Y direction and are grouped together as a pixel 120 in a driving operation. In a first mode, the subpixels forming the one pixel are individually turned on and off in response to gray scale data indicating the gray scale of the pixel. In a second mode, the subpixels forming the one pixel are supplied with a common voltage in response to the gray scale data indicating the gray scale of the pixel. In this way, the signal supplied to the data lines is binary regardless of the first mode or the second mode.Type: GrantFiled: May 21, 2001Date of Patent: November 15, 2005Assignee: Seiko Epson CorporationInventor: Tokuro Ozawa
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Publication number: 20050237273Abstract: To reduce the time for writing a voltage onto a gate of a driving transistor. In an initialization period, a node B is fixed to an initial voltage VINI, transistors are turned on, and a current flows into an OLED element, such that a voltage according to the current is held at the node A. Thereafter, the transistors are sequentially turned off, such that a threshold voltage of a driving transistor is held at the node A. In a writing period, a transistor is turned on and a data signal X-j is supplied, such that a voltage of the node B varies by the amount according to the current flowing into the OLED element. The voltage of the node A varies from the threshold voltage by the amount which is obtained by dividing the voltage variation by a capacitance ratio. In a light-emitting period, the transistor is turned on, such that a current according to the voltage of the node A flows into the OLED element.Type: ApplicationFiled: March 29, 2005Publication date: October 27, 2005Applicant: SEIKO EPSON CORPORATIONInventors: Tokuro Ozawa, Toshiyuki Kasai, Eiji Kanda, Ryoichi Nozawa
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Publication number: 20050237283Abstract: To reduce a time for applying a target voltage to a gate of a driving transistor. During an initializing period, both ends of a capacitive element become a short-circuited state by turning on transistors, so that node A and B becomes a voltage made by subtracting the threshold voltage Vthp of the driving transistor from a power source voltage VEL. During a writing period, the transistor is turned on and a data signal X-j is supplied to change the voltage at the node B as much as a voltage corresponding the current which is to flow into an OLED element. The node A is changed from the threshold voltage as much as the value obtained by dividing the voltage change by capacity ratio. During a light-emitting period, the transistor is turned on, so that the current corresponding to the voltage at the node A flows through the OLED element.Type: ApplicationFiled: March 29, 2005Publication date: October 27, 2005Applicant: SEIKO EPSON CORPORATIONInventors: Tokuro Ozawa, Eiji Kanda, Ryoichi Nozawa
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Patent number: 6927817Abstract: The invention provides a liquid crystal display device having a transmissive display region and a reflective display region in one dot region, and capable of obtaining a bright and high-contrast display in both a reflective display and a transmissive display. In particular, a liquid crystal display device according to the present invention can include a reflective display region and a transmissive display region provided in one dot region, and a reflection layer provided in the reflective display region. A pixel electrode, a TFT element for driving the pixel electrode, a capacitive electrode connected to the pixel electrode, an electrode part arranged to oppose the capacitive electrode via an insulating layer are formed in the dot region. Further, in the display regions within the dot region, the capacitive electrode or the capacitive line can be arranged at a position where it overlaps, in plan view, the inclined region between the reflective display region and the transflective display region.Type: GrantFiled: August 26, 2003Date of Patent: August 9, 2005Assignee: Seiko Epson CorporationInventors: Tomoyuki Itoh, Tokuro Ozawa
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Publication number: 20050116916Abstract: To increase a current value of a source line at the time of current programming. A device for driving an electro-optical panel in which a plurality of pixels each have an electro-optical element and active element means for selectively supplying electric charge to the electro-optical element through a source line in response to a write selection signal.Type: ApplicationFiled: November 23, 2004Publication date: June 2, 2005Applicant: Seiko Epson CorporationInventor: Tokuro Ozawa
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Patent number: 6897845Abstract: The voltage swing of a data signal, which is supplied to a data line, is maintained to be small, thereby reducing the power consumption. When a scanning signal supplied to a scanning line is set to an on-voltage, a data signal with a voltage, depending on the density and depending on the writing polarity, is applied to a data line. In this case, a TFT is turned on. Thus, a liquid crystal capacitor and storage capacitor store the charge corresponding to the voltage of the data signal. Then, the scanning signal is set to an off-voltage to turn the TFT off, and the voltage of the other terminal of the storage capacitor is raised from the low-level of capacitor voltage to the high-level, and the charge corresponding to the raised voltage amount is redistributed to the liquid crystal capacitor. Thus, the effective voltage value applied to the liquid crystal capacitor can correspond to the voltage swing of the data signal or more.Type: GrantFiled: December 7, 2001Date of Patent: May 24, 2005Assignee: Seiko Epson CorporationInventor: Tokuro Ozawa
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Publication number: 20050104508Abstract: A plurality of unit regions 51 are divided on a surface of a flat plate-shaped base substrate 10. In each of the plurality of unit regions 51, a pixel electrode 11 is formed. A counter electrode 15 is formed on an opposite side to the base substrate 10 with respect to the respective pixel electrodes 11. In pixel regions 511, which are regions constituting a predetermined image among the plurality of unit regions 51, OLED elements 21 are selectively formed. The OLED elements 21 are interposed between the respective pixel electrodes 11 and the counter electrode 15. In non-pixel regions 512, which are regions other than the pixel regions 511 among the plurality of unit regions 51, insulators 30 are formed. The insulators 30 are interposed between the respective pixel electrodes 11 and the counter electrode 15.Type: ApplicationFiled: October 6, 2004Publication date: May 19, 2005Applicant: Seiko Epson CorporationInventors: Tokuro Ozawa, Kenji Hayashi, Ayae Endo, Ryoichi Nozawa
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Publication number: 20050088378Abstract: To reduce time for writing a target voltage in the gate of a driving transistor. In a first period, a transistor 211 is switched on to allow a driving transistor 210 to function as a diode and transistors 212 and 213 are switched on to electrically connect the drain of the driving transistor 210 to a data line 112, to which an initial voltage is applied, such that the initial voltage is applied to the gate of the driving transistor 210. In a second period, a transistor 212 is switched off such that the gate of the driving transistor 210 is maintained to have an off voltage corresponding to the power source. In a third period, the transistor 211 is switched off such that the voltage of the data line 112 is converted into a grayscale voltage to maintain the gate of the driving transistor at the target voltage. In a fourth period, the driving transistor 210 flows the current corresponding to the maintained gate voltage to an OLED element 230.Type: ApplicationFiled: August 24, 2004Publication date: April 28, 2005Applicant: SEIKO EPSON CORPORATIONInventors: Tokuro Ozawa, Ryoichi Nozawa
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Patent number: 6864874Abstract: An electro-optical device is provided that can accurately supply voltages, which correspond to analog image signals, to pixels without being affected by switching noise and leakage, and that can perform high speed sampling of analog image signals. An analog image signal is first held in a capacitor. Thereafter, this analog image signal is converted by an A/D converter into a digital signal in a time that is shorter than one horizontal scanning period. Subsequently, the digital signal is held in a latch. Further, when the analog image signal is applied to a data line, the transfer of the digital signal from the latch to another latch and the D/A conversion thereof by a D/A converter are performed.Type: GrantFiled: October 13, 2000Date of Patent: March 8, 2005Assignee: Seiko Epson CorporationInventor: Tokuro Ozawa
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Publication number: 20050007318Abstract: The invention provides an electro-optical apparatus that can prevent a shift in a threshold voltage of an amorphous silicon transistor while driving an organic EL device in a pixel circuit including the amorphous silicon transistor. A characteristic-adjustment circuit can be provided, which has a function of returning a shift in the threshold voltage of the amorphous silicon transistor included in the pixel circuit to the original state.Type: ApplicationFiled: May 12, 2004Publication date: January 13, 2005Applicant: SEIKO EPSON CORPORATIONInventors: Toshiyuki Kasai, Yoichi Imamura, Tokuro Ozawa
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Publication number: 20050001794Abstract: To suppress an off leak current of a switching element arranged along a data line to control degradation of tonal gradation in an arrangement in which an organic electro-luminescent element OLED is driven using a current programming method, a first switching element is set to be in a non-conductive state and a second switching element is set to be in a conductive state during a normal mode. During a test mode, the first switching element is set to be in a conductive state while the second switching element is set to be in a non-conductive state.Type: ApplicationFiled: April 21, 2004Publication date: January 6, 2005Applicant: SEIKO EPSON CORPORATIONInventors: Hayato Nakanishi, Tokuro Ozawa, Takashi Miyazawa
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Publication number: 20050001247Abstract: The invention provides an electro-optical device that can include a plurality of scanning lines, a plurality of signal lines, a plurality of pixels arranged corresponding to intersections of the scanning lines and the signal lines, and heat-release sections. The pixels can each include corresponding transistors and corresponding light-emitting elements, the light-emitting elements emit light in the direction that light is withdrawn, and the heat-release sections include heat release portions, located on the side opposite to the light-withdrawing direction of the light-emitting elements, having electrical conductivity. Accordingly, the invention can enhance the environmental resistance of an electro-optical device including light-emitting elements.Type: ApplicationFiled: May 18, 2004Publication date: January 6, 2005Applicant: SEIKO EPSON CORPORATIONInventors: Tokuro Ozawa, Yoichi Imamura, Toshiyuki Kasai
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Publication number: 20040257353Abstract: The invention provides an electro-optical device having circuits for driving electro-optical elements, such as organic EL elements, and a driving device, which can employ driving elements having low driving ability, such as &agr;-TFTs. By providing a charge storage capacitor between the source electrode and the gate electrode of a driving transistor which is between power sources, the electro-optical device can allow the driving transistor to control a driving current, even when an electro-optical element is connected to the source side of the driving transistor. In addition, driving data can be stored in the charge storage capacitor by applying a predetermined voltage to the source electrode of the driving transistor.Type: ApplicationFiled: May 13, 2004Publication date: December 23, 2004Applicant: SEIKO EPSON CORPORATIONInventors: Yoichi Imamura, Toshiyuki Kasai, Tokuro Ozawa
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Publication number: 20040201555Abstract: The invention provides an electro-optical panel that stores data in pixels with a simple structure. In particular, pixels can be provided in association with intersections of data lines and scanning lines. Each of the pixels includes a hold capacitor, an inverter, an OLED element, and first to third transistors. At a reading period, data stored in the hold capacitor is inverted by the inverter and rewritten to the hold capacitor an even number of times. Thus, the logical level of the hold capacitor can be maintained. At a holding period, the second transistor is turned on. Also, the potential of a high potential source at the reading period is set to be higher than that at the holding period, and the potential of a low potential source at the reading period is set to be lower than that at the holding period.Type: ApplicationFiled: February 18, 2004Publication date: October 14, 2004Applicant: SEIKO EPSON CORPORATIONInventor: Tokuro Ozawa
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Electro-optical panel, method for driving the same, electro-optical device, and electronic equipment
Patent number: 6791523Abstract: To maintain image quality when a field frequency is dynamically changed. In an image display area AA, control lines 4a are arranged respectively corresponding to scanning lines 3a, and TFTs 50 and 51, a pixel electrode 9a, and a storage capacitor 52 are arranged at each intersection of one of data lines 6a and scanning lines 3a. A control signal SC supplied through the control line 4a controls the TFT 51 for an on and off operation. A timing signal generator circuit 300 activates the control signal SC when a field frequency is not higher than 60 Hz, and deactivates the control signal SC when a field frequency is above 60 Hz. In this way, whether or not to connect the storage capacitor 52 to the pixel electrode 9a is determined.Type: GrantFiled: July 24, 2001Date of Patent: September 14, 2004Assignee: Seiko Epson CorporationInventors: Shin Fujita, Tokuro Ozawa -
Patent number: 6784880Abstract: The invention prevents shift register circuits from malfunctioning. A distribution circuit outputs a trailing trigger pulse DTP and a leading trigger pulse UTP. A trailing edge control circuit and a leading edge control circuit delay the trailing trigger pulse DTP and the leading trigger pulse UTP, respectively. The delay time of each of these control circuits can be set. These delay times are determined according to a threshold voltage of a TFT constituting a shift register. An inverted clock signal CLYINV is generated according to output signals of the control circuits. The shift register is driven by a clock signal CLY and an inverted clock signal CLYINV.Type: GrantFiled: December 8, 2000Date of Patent: August 31, 2004Assignee: Seiko Epson CorporationInventors: Shin Fujita, Tokuro Ozawa
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Patent number: 6781565Abstract: Lamp wave signals are supplied to signal supply lines via switches. The switches are turned ON when their corresponding scanning lines are selected. Hence, a load on the driving circuit for the lamp wave signals will be a parasitic capacitance that comes from a single signal supply line. PWM signals of having pulse widths based on image data are supplied to data lines. A TFT supplies PWM signals to a gate electrode of a TFT when a corresponding scanning line is selected; therefore, the lamp wave signal is applied to a pixel electrode via the TFT when the data line and the scanning line simultaneously become active.Type: GrantFiled: December 22, 2000Date of Patent: August 24, 2004Assignee: Seiko Epson CorporationInventor: Tokuro Ozawa
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Patent number: 6778163Abstract: The present invention provides a liquid crystal display in which a voltage amplitude of a data signal which is supplied to a data line, is kept small, thereby reducing the power consumption. When a scanning signal supplied to a scanning line is set to an H level, a data signal with the voltage depending on the gray level and depending on the writing polarity is applied to a data line. In this case, a thin-film transistor (TFT) is turned on, thus a liquid crystal capacitor and storage capacitor store the charge corresponding to the data signal. Then, the scanning signal is set to an L level to turn TFT off, and the voltage of the other terminal of the storage capacitor is raised from the low side of capacitor voltage Vst(−) to the high side Vst((+)), and the charge corresponding to the raised voltage amount is redistributed to the liquid crystal capacitor.Type: GrantFiled: December 20, 2001Date of Patent: August 17, 2004Assignee: Seiko Epson CorporationInventor: Tokuro Ozawa
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Publication number: 20040095530Abstract: The invention provides a liquid crystal display device having a transmissive display region and a reflective display region in one dot region, and capable of obtaining a bright and high-contrast display in both a reflective display and a transmissive display. In particular, a liquid crystal display device according to the present invention can include a reflective display region and a transmissive display region provided in one dot region, and a reflection layer provided in the reflective display region. A pixel electrode, a TFT element for driving the pixel electrode, a capacitive electrode connected to the pixel electrode, an electrode part arranged to oppose the capacitive electrode via an insulating layer are formed in the dot region. Further, in the display regions within the dot region, the capacitive electrode or the capacitive line can be arranged at a position where it overlaps, in plan view, the inclined region between the reflective display region and the transflective display region.Type: ApplicationFiled: August 26, 2003Publication date: May 20, 2004Applicant: Seiko Epson CorporationInventors: Tomoyuki Itoh, Tokuro Ozawa
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Patent number: 6714046Abstract: The invention simplifies the configuration of a level shifter and to allow fast operation. A level shifter includes a capacitor, to a first end of which a low-amplitude logic signal is input; first TFTs to apply an offset voltage to a second end of the capacitor; a capacitor, to a first end of which the low-amplitude logic signal is input; third TFTs to apply an offset voltage to a second end of the capacitor; and second TFTs connected in series between a supply line of a power supply voltage for a high-amplitude logic signal and a supply line of a reference voltage therefor, a node therebetween serving as an output terminal. A threshold voltage of one of the second TFTs is set to be not higher than the offset voltage applied by the first TFTs , and an offset voltage of the other of the second TFTs is set to be higher than or equal to the offset voltage applied by the third TFTs.Type: GrantFiled: June 20, 2002Date of Patent: March 30, 2004Assignee: Seiko Epson CorporationInventors: Shinsuke Fujikawa, Tokuro Ozawa