KR100627338B1 - LED display device - Google Patents

Abstract

An organic EL light emitting display device comprising: a light emitting display device having a photodetecting device for gamma correction. The light detecting device according to the present invention comprises: an optical sensor for detecting an external light amount and outputting an analog voltage signal corresponding to the light amount; Using a variable power supply voltage provided to the optical sensor in common, comparing a plurality of reference voltage and the analog voltage signal that is variable set according to the variable power supply voltage, and outputs a plurality of voltage levels respectively corresponding to the magnitude A voltage comparator; And an encoder for converting and outputting a plurality of voltage levels output from the voltage comparator to a specific address of N bits. According to the present invention, by changing the voltage variable range of the comparator in the photodetector, it is possible to detect the external light amount irrespective of the type of the optical sensor, and also to accurately detect the external optical sensor by adapting to the external environment. Therefore, more accurate gamma correction can be achieved.

Light Emitting Display, Organic EL, Light Sensor, Photodetector, Comparator, Encoder, Gamma Correction

Description

Light emitting display device

1 is a diagram showing the light emission principle of an organic EL.

2 is a schematic block diagram of an organic EL display device according to an embodiment of the present invention.

3 is a diagram illustrating an organic EL display panel using an active driving method using a thin film transistor (TFT) according to an embodiment of the present invention.

4 is a configuration diagram of a light emitting display device according to an exemplary embodiment of the present invention.

5 is a diagram for describing an operation of a comparator of a light emitting display device according to an exemplary embodiment of the present invention.

6 is a table illustrating various reference voltage settings set in a comparator of a light emitting display device according to an exemplary embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting display device, and more particularly, to an organic light emitting display device comprising a light detecting device for gamma correction.

An organic electroluminescence (EL) display device is a device for displaying an image by controlling an amount of current flowing through these organic materials by dividing an organic material emitting light when the current flows into pixels in a matrix form. Such an organic EL display device is expected to be a next generation display device due to advantages such as low voltage driving, light weight, wide viewing angle, and high speed response.

1 is a diagram showing the light emission principle of organic EL, respectively.

In general, an organic EL display device is a display device for electrically exciting a fluorescent organic compound to emit light, and is capable of displaying an image by driving voltage or current by driving N × M organic light emitting cells. As shown in FIG. 1, the organic light emitting cell structure has a structure of an indium tin oxide (ITO) pixel electrode, an organic thin film, and a metal layer, and the organic thin film has a good balance between electrons and holes to improve light emission efficiency. In order to achieve this, a multi-layered structure including an emitting layer (EML), an electron transport layer (ETL), and a hole transport layer (HTL) is formed, and a separate electron injection layer (EIL) is used. ) And a hole injecting layer (HIL).

As such a method of driving the organic light emitting cell, there are a simple matrix method and an active matrix method using a TFT. In the simple matrix method, the anode and the cathode are orthogonal and the line is selected and driven, whereas the active driving method is a driving method in which a TFT and a capacitor are connected to respective pixel electrodes to maintain a voltage by capacitor capacitance.

However, the conventional organic EL light emitting display device detects an external light amount using an optical sensor. Since the optical sensor has an output value different according to its manufacturer or type, it is difficult to accurately detect the optical sensor and thus gamma correction. There is a problem that performance is not made correctly.

An object of the present invention for solving the above problems is to provide a light detecting device capable of detecting the amount of external light regardless of the type of light sensor in the organic EL light emitting display device.

In addition, another object of the present invention is to provide a light emitting display device that can be corrected by the gamma correction by accurately detecting the external light sensor in accordance with the external environment.

As a means for achieving the above object, the photodetecting device according to the present invention,

An optical sensor for detecting an external light amount and outputting an analog voltage signal corresponding to the light amount;

The variable power supply voltage Vcc provided to the optical sensor is commonly used, and a plurality of voltage levels corresponding to the magnitudes are compared by comparing the plurality of reference voltages that are variably set according to the variable power supply voltage with the analog voltage signal. A voltage comparator for outputting the same; And

An encoder for converting a plurality of voltage levels output from the voltage comparator to a specific address of N bits and outputs

Characterized in that it comprises a.

Here, the voltage comparator includes: 2 ^N distribution resistors connected in series with the variable power supply voltage Vcc; And a reference voltage (Vref) node is connected between each node of the distribution resistor, and the analog voltage signal is respectively connected to a comparison voltage node, and the voltage level is compared by comparing the reference voltage (Vref) and the analog voltage signal, respectively. It may include 2 ^N -1 comparators to output.

Here, the comparator may be a non-inverting comparator that outputs a high or low level voltage after the reference voltage Vref is connected to a negative terminal and the analog voltage signal is connected to a positive terminal to determine a magnitude thereof. have.

Here, the comparator may be an inverting comparator for connecting the reference voltage Vref to a positive terminal and connecting the analog voltage signal to a negative terminal to determine a magnitude thereof and then output a high or low level voltage. .

Here, the variable power supply voltage (Vcc) commonly connected to the voltage comparing unit and the optical sensor is characterized in that the range of 2.7 to 5.5V.

On the other hand, as a means for achieving the above object, the light emitting display device according to the present invention,

A display panel configured to emit light by emitting a plurality of pixels respectively connected to the plurality of data lines and the scan lines;

An optical sensor for detecting an external light amount and outputting an analog voltage signal corresponding to the light amount;

A scan driver for sequentially applying a selection signal to the plurality of scan lines, respectively; And

A data driver which applies a data voltage corresponding to an image signal to each pixel selected by the plurality of scan lines, and performs gamma correction according to a previously stored gamma characteristic curve corresponding to the amount of light detected by the optical sensor.

Including;

The data driver,

Using a variable power supply voltage provided to the optical sensor in common, comparing a plurality of reference voltage and the analog voltage signal that is variable set according to the variable power supply voltage, and outputs a plurality of voltage levels respectively corresponding to the magnitude A voltage comparator;

An encoder for converting and outputting a plurality of voltage levels output from the voltage comparator to a specific address of N bits; And

A gamma correction circuit for outputting a gamma-corrected output signal according to a pre-stored gamma characteristic curve corresponding to a specific address output from the encoder

Characterized in that it comprises a.

According to the present invention, by changing the comparator voltage variable range of the light detecting device, it is possible to detect the external light amount irrespective of the type of the optical sensor, and also by detecting the external light sensor accurately by adapting to the external environment, gamma Correction is made accurately.

Hereinafter, the configuration and operation of a light emitting display device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic block diagram of an organic EL display device according to an embodiment of the present invention.

Referring to FIG. 2, an organic EL display device according to an exemplary embodiment of the present invention includes a video controller 100, a panel controller 200, a power module 300, a scan driver 400, a data driver 500, and an organic EL. It may be made of a panel 600.

In the organic EL display device according to the embodiment of the present invention, a plurality of signals passing through the analog interface and the digital interface are respectively arranged in the organic EL panel 600 by the scan driver 440 and the data driver 500. It is provided in the row direction.

Specifically, various analog signals such as R, G, B signals, and synchronization signals are input to the video controller 100 and then converted into digital signals, and the panel controller 200 controls them to sequentially scan the driver 400. And the data driver 500, the organic EL panel 600 is provided by the scan driver 400 and the data driver 500, and the power supply device 400. An n × m organic light emitting cell is driven by voltage or current by a power supply to represent an image.

3 is a diagram illustrating an organic EL display panel using an active driving method using a TFT according to an embodiment of the present invention.

Referring to FIG. 3, an organic EL display device according to an exemplary embodiment of the present invention includes an organic EL display panel 600, a data driver 400, and a scan driver 500.

The organic EL display panel 600 includes m data lines D1, D2, ..., Dm extending in the column direction, n scan lines S1, S2, ..., Sn extending in the row direction, and n × m. Pixel circuits. The m data lines D1, D2, ..., Dm transfer data signals representing an image signal to the pixel circuits, and the n scan lines S1, S2, ..., Sn transfer respective selection signals to the pixel circuits. . Here, the pixel circuit is formed in one pixel region 610 defined by two neighboring data lines D1, D2,..., And Dm and two neighboring scan lines S1, S2,..., Sn.

The scan driver 400 sequentially applies selection signals to the n scan lines S1, S2,..., And Sn, and the data driver 500 images the m data lines D1, D2,..., And Dm. The data voltage corresponding to the signal is applied.

In addition, the scan driver 330 and / or the data driver 320 may be electrically connected to the organic EL display panel 600, or a tape carrier adhered to and electrically connected to the organic EL display panel 600. The package may be mounted in a chip carrier package (TCP). Alternatively, the display panel 600 may be attached to a flexible printed circuit (FPC) or a film that is adhered to and electrically connected to the display panel 600 in the form of a chip.

In addition, the scan driver 400 and / or the data driver 500 may be directly mounted on the glass substrate of the organic EL display panel 600, or may be formed of the same layers as the scan line, the data line, and the thin film transistor on the glass substrate. It may be replaced with the driving circuit formed or may be directly mounted.

The pixel circuit also includes an organic EL element OLED, two transistors SM and DM and a capacitor Cst. For example, the two transistors SM and DM may be formed as PMOS transistors.

The driving transistor DM has a source connected to the power supply voltage VDD, and a capacitor Cst connected between the gate and the source. The capacitor Cst maintains the gate-source voltage of the driving transistor DM for a predetermined period, and the driving transistor DM corresponds to a voltage held by the capacitor Cst, that is, a voltage between the gate and the source. Output the current. The switching transistor SM transfers the data signal from the data line Dm to the driving transistor DM in response to the selection signal from the current scan line Sn.

The organic EL element OLED has a cathode connected to a reference voltage Vss and emits light corresponding to a current applied through the driving transistor DM. Here, the power source Vss connected to the cathode of the organic EL element OLED is a voltage having a lower level than the power source VDD, and a ground voltage or the like may be used.

4 is a configuration diagram of a light emitting display device according to an embodiment of the present invention, wherein the light emitting display device according to the embodiment of the present invention includes a voltage comparator 710, an encoder 720, a gamma correction table 730, and the like. A driving integrated circuit 700 having a gamma correction circuit 740, and an optical sensor 800, and a voltage comparator 710 for comparing the voltage as the voltage supplied to the optical sensor 800 is changed. When the reference voltage of the variable is detected and the predetermined output is inputted to the encoder 720, the encoder 720 selects a predetermined gamma characteristic curve according to four logics, for example, two bits. Gamma correction is performed.

On the other hand, the gamma correction will be described as follows. Most imaging devices (imaging tubes, CCDs, MOS, etc.) have a linear photoelectric conversion characteristic (gamma = 1.0) with respect to incident light. Image distortion due to mismatched conversion characteristics. Therefore, gamma correction is performed to compensate for any nonlinear response to cancel out the nonlinear (gamma = 2.2) characteristic of the organic EL light emitting display of the display, resulting in a light emission sensitivity proportional to the output current.

In particular, as the technology of digitally processing image signals is widely applied, a gamma correction device made of digital circuits is used. Typically, a gamma correction characteristic of an input-to-output gamma correction characteristic is mapped to a specific address of a memory. Mapping systems that obtain gamma characteristics of video signals by storing gamma-corrected output signals stored at a corresponding address in a memory according to the level of the input video signal after being stored in advance are well known. Among these mapping systems, the gamma characteristic curve is divided into a plurality of sections according to the level of the input signal, and a gamma approximated by a polygonal line formed by connecting a series of approximated straight lines approximated to the gamma characteristic curve for each section. A gamma correction device for performing gamma correction using a characteristic curve is known. This gamma correction device has a picture adjustment input that allows the color, brightness and tint of the image to be adjusted.

Referring back to FIG. 4, in the light emitting display device according to the exemplary embodiment of the present invention, the optical sensor 800 detects an external light amount and outputs an analog voltage signal corresponding to the light amount.

The voltage comparison unit 710 commonly uses a variable power supply voltage Vcc provided to the optical sensor 800, and includes a plurality of reference voltages Vref that are variably set according to the variable power supply voltage Vcc. The analog voltage signal AVout is compared, and a plurality of voltage levels respectively corresponding to the magnitudes are output. The plurality of voltage levels may be a high level H of + Vs or a low level L of −Vs, and the low level is typically the ground voltage GND. In addition, the variable power supply voltage Vcc commonly connected to the voltage comparator 710 and the optical sensor 800 has a range of 2.7 to 5.5V, and is typically 3V.

The encoder 720 converts a plurality of voltage levels output from the voltage comparator 710 into a specific address of N bits and outputs the converted address. That is, four logic "00, 01, 10, or 11", which is two bits, is output in response to the plurality of voltage levels output from the voltage comparator 710.

The gamma correction circuit 740 outputs a gamma corrected output signal according to a pre-stored gamma characteristic curve corresponding to a specific address output from the encoder 720, wherein the gamma characteristic curve is stored in the memory 730. It is stored.

In this case, the voltage comparator 710 includes 2 ^N distribution resistors R1, R2, R3, and r4 connected in series with the variable power supply voltage Vcc, and a reference voltage between nodes of the distribution resistors. (Vref) node (-) is connected, and the analog voltage signal (AVout) is connected to the comparison voltage node (+), respectively, and compares the reference voltage (Vref) and the analog voltage signal (AVout), respectively, the voltage level 2 ^N -1 comparators 711, 712, 713, and 714 for outputting the same.

Here, the comparators 711, 712, 713, and 714 have the reference voltage Vref connected to a negative terminal (−) and the analog voltage signal connected to a positive terminal (+), and determine the magnitude thereof. It may be a non-inverting comparator that outputs a high or low level voltage. In addition, the comparators 711, 712, 713, and 714 have a high or low level after the reference voltage Vref is connected to a positive terminal and the analog voltage signal is connected to a negative terminal. It may be an inverting comparator that outputs a voltage.

5 is a diagram illustrating an example of a comparator of a light emitting display device according to an embodiment of the present invention.

Referring to FIG. 5, in the comparator 710 of the light emitting display device according to the embodiment of the present invention, for example, an input voltage Vin is connected to a positive terminal of the comparators 711, 712, 713, and 174. The reference voltage Vref is connected to the negative terminals of the comparators 711, 712, 713, 174. If the input voltage Vin is slightly larger than the reference voltage Vref, the predetermined + Vs voltage is output as a high logic value "1", and the input voltage Vin is slightly smaller than the reference voltage Vref. In this case, the non-inverting comparator outputs the predetermined -Vs voltage at a low logic value ("0"). Of course, it can be implemented as an inverting comparator where the input voltage Vin is connected to the negative terminal of the comparator and the reference voltage Vref is connected to the positive terminal of the comparator, in which case the encoding is different in the next stage of encoder. It is self-evident. According to the exemplary embodiment of the present invention, the reference voltage Vref of the comparators 711, 712, 713, and 174 may vary depending on the power supply voltage Vcc. That is, when the power supply voltage Vcc varies between 2.7 and 5.5V, the reference voltage Vref connected thereto also depends on the power supply voltage Vcc and the distribution resistor. In other words, when the optical sensor 800 and the reference voltage Vref use the same power supply voltage Vcc, the reference voltage Vref may be changed according to the change of the power supply voltage Vcc. In addition, the reference voltage can be set in various ways according to the distribution resistor (R).

6 is a table illustrating various set voltages set in a comparator of a light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 6, as described above, by varying the reference voltage Vref according to the change of the power supply voltage Vcc, it is possible to set various reference voltages for reference nodes 00, 01, 10, and 11. But it is not limited thereto. That is, in the optical sensor 800 and the comparator 710, the power supply voltage Vcc is commonly used, and various reference voltages can be set as shown by using the distribution resistors R1, R2, R3, and R4. Accordingly, optical sensors of various voltage ranges may be used regardless of the manufacturer or type.

As a result, in the embodiment of the present invention, the power supply voltage Vcc of the optical sensor is supplied from the driving integrated circuit 700 to distribute the resistance by using a distribution resistor to make a variable reference voltage of the comparator, and the driving integrated circuit ( By providing the voltages (+ Vs and -Vs) of the OP-AMP used in the comparator, 700 may implement a light emitting display device having an optical sensor capable of detecting various voltage ranges.

While the invention has been shown and described in connection with specific embodiments thereof, it will be appreciated that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the claims. Anyone who owns it can easily find out.

According to the present invention, by changing the comparator voltage variable range of the light detecting device, it is possible to detect the external light amount irrespective of the type of the optical sensor, and also by detecting the external light sensor accurately by adapting to the external environment, gamma Correction is made accurately.

Claims (8)

In the light detection device for gamma correction of the light emitting display device, An optical sensor for detecting an external light amount and outputting an analog voltage signal AVout corresponding to the light amount; The variable power supply voltage Vcc provided to the optical sensor is commonly used, and the analog voltage signal AVout is compared with a plurality of reference voltages Vref that are variably set according to the variable power supply voltage Vcc. A voltage comparator for outputting a plurality of voltage levels respectively corresponding to the magnitudes; An encoder for converting and outputting a plurality of voltage levels output from the voltage comparator to a specific address of N bits; And A gamma correction circuit for outputting a gamma-corrected output signal according to a pre-stored gamma characteristic curve corresponding to a specific address output from the encoder Photodetecting device comprising a. The method of claim 1, wherein the voltage comparison unit, 2 ^N distribution resistors connected in series with the variable power supply voltage Vcc; And A reference voltage (Vref) node is connected between each node of the distribution resistor, and the analog voltage signal AVout is connected to a comparison voltage node, respectively, so that the reference voltage Vref and the analog voltage signal AVout are respectively. 2 ^N -1 comparators to output voltage levels in comparison Photodetecting device comprising a. The method of claim 2, The comparator is a non-inverting comparator that is connected to a negative terminal of the reference voltage (Vref), the analog voltage signal (AVout) is connected to a positive terminal, and outputs a high or low level voltage after determining the magnitude Photodetecting device, characterized in that. The method of claim 2, The comparator is an inverting comparator that is connected to the positive terminal of the reference voltage (Vref), the analog voltage signal (AVout) is connected to the negative terminal, and determines the magnitude of the comparator and outputs a voltage of high or low level The photodetector device characterized by the above-mentioned. The method according to claim 1 or 2, The variable power supply voltage (Vcc) commonly connected to the voltage comparator and the optical sensor is in the range of 2.7 to 5.5V. A display panel configured to emit light by emitting a plurality of pixels respectively connected to the plurality of data lines and the scan lines; An optical sensor for detecting an external light amount and outputting an analog voltage signal corresponding to the light amount; A scan driver for sequentially applying a selection signal to the plurality of scan lines, respectively; And A data driver which applies a data voltage corresponding to an image signal to each pixel selected by the plurality of scan lines, and performs gamma correction according to a previously stored gamma characteristic curve corresponding to the amount of light detected by the optical sensor. Including; The data driver, Using a variable power supply voltage provided to the optical sensor in common, comparing a plurality of reference voltage and the analog voltage signal that is variable set according to the variable power supply voltage, and outputs a plurality of voltage levels respectively corresponding to the magnitude A voltage comparator; An encoder for converting and outputting a plurality of voltage levels output from the voltage comparator to a specific address of N bits; And A gamma correction circuit for outputting a gamma-corrected output signal according to a pre-stored gamma characteristic curve corresponding to a specific address output from the encoder Light emitting display device comprising a. The method of claim 6, wherein the voltage comparison unit, 2 ^N distribution resistors connected in series with the variable power supply voltage; And A reference voltage node is connected between each node of the distribution resistor, and the analog voltage signal is connected to a comparison voltage node, respectively, and 2 ^N -1 output voltage levels by comparing the reference voltage and the analog voltage signal, respectively. Comparator Light emitting display device comprising a. The method according to claim 6 or 7, The variable power supply voltage commonly connected to the voltage comparator and the optical sensor is in the range of 2.7 to 5.5V.

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