Method for Driving Semiconductor Device

• US 20100220117A1
• Filed: 02/18/2010
• Published: 09/02/2010
• Est. Priority Date: 02/27/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime
• Granted Patent: US 9,047,815 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: H01L 2029/7863 with an LDD consisting of more than one lightly doped zone or having a non-homogeneous dopant distribution, e.g. graded LDD
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/78621 with LDD structure or an extension or an offset region or characterised by the doping profile

Abstract

To provide a method for driving a semiconductor device, by which influence of variation in threshold voltage and mobility of transistors can be reduced. The semiconductor device includes an n-channel transistor, a switch for controlling electrical connection between a gate and a first terminal of the transistor, a capacitor electrically connected between the gate and a second terminal of the transistor, and a display element. The method has a first period for holding the sum of a voltage corresponding to the threshold voltage of the transistor and an image signal voltage in the capacitor; a second period for turning on the switch so that electric charge held in the capacitor in accordance with the sum of the image signal voltage and the threshold voltage is discharged through the transistor; and a third period for supplying a current to the display element through the transistor after the second period.

Claims

1. A method for driving a semiconductor device, the semiconductor device comprising:

a transistor with n-type conductivity;

a switch configured to control a conduction state between a gate of the transistor and a first terminal of the transistor;

a capacitor electrically connected between the gate of the transistor and a second terminal of the transistor; and

a display element,

wherein the method for driving the semiconductor device includes;

in a first period, holding a sum of a voltage corresponding to a threshold voltage of the transistor and an image signal voltage in the capacitor,

in a second period, turning on the switch so that electric charge held in the capacitor in accordance with the sum of the image signal voltage and the threshold voltage is discharged through the transistor, and

in a third period, supplying a current to the display element through the transistor after the second period.

2. A method according to claim 1, wherein the transistor includes an oxide semiconductor comprising one material selected from the group consisting of ZnO, a-InGaZnO, SiGe, GaAs, IZO, ITO, SnO, TiO, and AlZnSnO.

3. A method for driving a semiconductor device, the semiconductor device comprising:

a transistor with n-type conductivity;

a switch configured to control a conduction state between a gate of the transistor and a first terminal of the transistor;

a capacitor electrically connected between the gate of the transistor and a second terminal of the transistor; and

a display element,

wherein the method for driving the semiconductor device includes;

in a first period, holding a voltage corresponding to a threshold voltage of the transistor in the capacitor,

in a second period, holding a sum of the voltage corresponding to the threshold voltage of the transistor and an image signal voltage in the capacitor,

in a third period, turning on the switch so that electric charge held in the capacitor in accordance with the sum of the image signal voltage and the threshold voltage is discharged through the transistor, and

in a fourth period, supplying a current to the display element through the transistor after the third period.

4. A method according to claim 3, wherein the transistor includes an oxide semiconductor comprising one material selected from the group consisting of ZnO, a-InGaZnO, SiGe, GaAs, IZO, ITO, SnO, TiO, and AlZnSnO.

5. A method for driving a semiconductor device, the semiconductor device comprising:

a transistor with n-type conductivity;

a switch configured to control a conduction state between a gate of the transistor and a first terminal of the transistor;

a capacitor electrically connected between the gate of the transistor and a second terminal of the transistor; and

a display element,

wherein the method for driving the semiconductor device includes;

in a first period, initializing a voltage held in the capacitor,

in a second period, holding a voltage corresponding to a threshold voltage of the transistor in the capacitor,

in a third period, holding a sum of the voltage corresponding to the threshold voltage of the transistor and an image signal voltage in the capacitor,

in a fourth period, turning on the switch so that electric charge held in the capacitor in accordance with the sum of the image signal voltage and the threshold voltage is discharged through the transistor, and

in a fifth period, supplying a current to the display element through the transistor after the fourth period.

6. A method according to claim 5, wherein the transistor includes an oxide semiconductor comprising one material selected from the group consisting of ZnO, a-InGaZnO, SiGe, GaAs, IZO, ITO, SnO, TiO, and AlZnSnO.