SEMICONDUCTOR APPARATUS

• US 20200135119A1
• Filed: 10/22/2019
• Published: 04/30/2020
• Est. Priority Date: 10/26/2018
• Status: Active Grant

• Current Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Original Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Inventors: Nakayama, Akira
• Granted Patent: US 11,100,869 B2
• Time in Patent Office: Days
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A semiconductor apparatus including a driver capable of favorably suppressing image deterioration accompanying a voltage fluctuation even if the voltage fluctuation is generated in a display device is provided. The semiconductor apparatus of the disclosure includes: a gradation voltage generation portion generating a first to kth representative gradation voltage in accordance with gamma characteristics and generating a first to Nth gradation voltage based on the first to kth representative gradation voltage; a driving portion selecting one gradation voltage corresponding to display data from the first to Nth gradation voltage and applying a signal representing the selected one gradation voltage as a driving signal to source lines; and a fluctuating voltage superposition portion generating, when a voltage fluctuation is generated in the power supply voltage for making display cells emit light, a voltage fluctuation corresponding to the voltage fluctuation in at least one of the first to kth representative gradation voltage.

Claims

1. A semiconductor apparatus which drives a display device comprising source lines which receive driving signals corresponding to brightness levels represented by display data and display cells which emit light at brightness corresponding to the driving signals received by the source lines based on a power supply voltage, the semiconductor apparatus comprising:

a gradation voltage generation portion generating a first representative gradation voltage to a kth representative gradation voltage in accordance with gamma characteristics and generating a first gradation voltage to an Nth gradation voltage based on the first representative gradation voltage to the kth representative gradation voltage, wherein k is an integer greater than 2 and N is an integer greater than k;

a driving portion selecting one gradation voltage corresponding to the display data from the first gradation voltage to the Nth gradation voltage and applying a signal representing the selected one gradation voltage as the driving signal to the source lines; and

a fluctuating voltage superposition portion generating, when a voltage fluctuation is generated in the power supply voltage, a voltage fluctuation corresponding to the voltage fluctuation in at least one of the first representative gradation voltage to the kth representative gradation voltage.

2. The semiconductor apparatus according to claim 1, wherein the gradation voltage generation portion comprises:

a basic gradation voltage generation portion generating a plurality of basic gradation voltages having voltage values different from each other;

a red gamma correction circuit setting k of the plurality of basic gradation voltages in accordance with a gamma characteristic for red as the first representative gradation voltage to the kth representative gradation voltage for red and generating the first gradation voltage to the Nth gradation voltage for red based on the first representative gradation voltage to the kth representative gradation voltage for red;

a green gamma correction circuit setting k of the plurality of basic gradation voltages in accordance with a gamma characteristic for green as the first representative gradation voltage to the kth representative gradation voltage for green and generating the first gradation voltage to the Nth gradation voltage for green based on the first representative gradation voltage to the kth representative gradation voltage for green; and

a blue gamma correction circuit setting k of the plurality of basic gradation voltages in accordance with a gamma characteristic for blue as the first representative gradation voltage to the kth representative gradation voltage for blue and generating the first gradation voltage to the Nth gradation voltage for blue based on the first representative gradation voltage to the kth representative gradation voltage for blue; and

the fluctuating voltage superposition portion generates, in each of the red gamma correction circuit, the green gamma correction circuit, and the blue gamma correction circuit, the voltage fluctuation corresponding to the voltage fluctuation generated in the power supply voltage in at least one of the first representative gradation voltage to the kth representative gradation voltage.

3. The semiconductor apparatus according to claim 1, comprising a first line to a kth line for transmitting the first representative gradation voltage to the kth representative gradation voltage, wherein

the fluctuating voltage superposition portion comprises a capacitor in which the power supply voltage is applied to a first electrode of the capacitor and a second electrode of the capacitor is connected to at least one of the first line to the kth line.

4. The semiconductor apparatus according to claim 1, wherein the fluctuating voltage superposition portion comprises:

an operational amplifier;

a first resistor having one end to which one of the first representative gradation voltage to the kth representative gradation voltage is applied and the other end connected to a non-inverted input terminal of the operational amplifier;

a second resistor having one end to which the power supply voltage is applied and the other end connected to the non-inverted input terminal of the operational amplifier;

a third resistor having one end to which a reference power supply voltage which is a reference of the power supply voltage is applied and the other end connected to an inverted input terminal of the operational amplifier; and

a fourth resistor having one end connected to the inverted input terminal of the operational amplifier and the other end connected to an output terminal of the operational amplifier.

5. The semiconductor apparatus according to claim 1, wherein the fluctuating voltage superposition portion generates a voltage fluctuation corresponding to the voltage fluctuation generated in the power supply voltage in one representative gradation voltage having the greatest voltage value among the first representative gradation voltage to the kth representative gradation voltage.

6. The semiconductor apparatus according to claim 3, wherein the display cell comprises:

a light emission element;

a holding capacitor in which the driving signal received by the source line is received by a first electrode of the holding capacitor and the power supply voltage is applied to a second electrode; and

a transistor in which the driving signal is supplied to a gate while the power supply voltage is applied to a source, and a current corresponding to the driving signal is supplied to the light emission element; and

wherein

the capacitor included in the fluctuating voltage superposition portion has an electrostatic capacitance corresponding to an electrostatic capacitance of the holding capacitor.

7. The semiconductor apparatus according to claim 3, wherein the display device comprises a power supply line supplying the power supply voltage to each of the plurality of display cells and terminals connected to the power supply line;

and

the first electrode of the capacitor is connected to the terminals.

8. The semiconductor apparatus according to claim 1, wherein the fluctuating voltage superposition portion is disposed inside the gradation voltage generation portion.