KR100570778B1 - A light emitting device, and Gamma correction methods thereof - Google Patents

Abstract

The present invention relates to a light emitting display device in which gamma correction is performed for each sensor mode or user mode, and a gamma correction method thereof. A gamma correction device according to the present invention includes an optical sensor for outputting an analog voltage signal corresponding to the detected external light amount; A voltage comparison unit comparing a plurality of preset reference voltages with the analog voltage signal and 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; Fine adjustment unit for the user to fine-tune the brightness of the display panel step by step; A memory in which data corresponding to a gamma characteristic curve for each sensor mode corresponding to the specific address and a gamma characteristic curve for each user mode corresponding to an adjustment amount of the fine control unit are stored; And a gamma correction circuit for outputting a gamma corrected output signal according to a gamma characteristic curve previously stored in response to a specific address output from the encoder or the user's selection. According to the present invention, the user may select a plurality of fine gamma corrections provided for each sensor mode or user mode, and thus the user may arbitrarily adjust the display brightness.

Light Emitting Display, Organic EL, Gamma Correction, Sensor Mode, User Mode

Description

A light emitting device, and Gamma correction methods

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 schematic block diagram of a gamma correction apparatus of a light emitting display device according to an exemplary embodiment of the present invention.

5 is a detailed block diagram of a gamma correction device of a light emitting display device according to an exemplary embodiment of the present invention.

6 is a table illustrating luminance modes for each stage according to an exemplary embodiment of the present invention.

7 is a flowchart illustrating a gamma correction method 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 a gamma correction method thereof. More particularly, the present invention relates to a light emitting display device and a gamma correction method in which an gamma correction is performed for each sensor mode or a user mode.

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 is 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 has a problem in that the user cannot arbitrarily select a gamma correction level because the external light amount is automatically detected by using a light sensor.

An object of the present invention for solving the above problems is a user can select a plurality of fine gamma correction provided for each sensor mode or user mode in the organic EL light emitting display device, and accordingly the user can arbitrarily adjust the display brightness It is to provide a display device and a gamma correction method thereof.

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

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

A voltage comparison unit comparing a plurality of preset reference voltages Vref with the analog voltage signal AVout and outputting a plurality of voltage levels corresponding to the magnitudes of the plurality of reference voltages Vref;

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

Fine adjustment unit for the user to fine-tune the brightness of the display panel step by step;

A memory in which data corresponding to a gamma characteristic curve for each sensor mode corresponding to the specific address and a gamma characteristic curve for each user mode corresponding to an adjustment amount of the fine control unit are stored; And

A gamma correction circuit for outputting a gamma-corrected output signal according to each of the previously stored gamma characteristic curves in response to a specific address output from the encoder or the user's selection

Characterized in that it comprises a.

The memory may store data corresponding to the gamma characteristic curve in the form of a look-up table (LUT).

The sensor mode and the user mode may be selected by a command register in the driving integrated circuit.

Here, the sensor mode is characterized in that after the gamma correction according to the operation of the optical sensor, the user can directly select the level to perform a finely adjusted gamma correction.

Here, the user mode may include a switch for the user to directly select a level.

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;

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

A data driver for applying a data voltage corresponding to an image signal to each pixel selected by the plurality of scan lines;

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

 A driving controller which drives the data driver and the scan driver and performs gamma correction according to a pre-stored gamma characteristic curve corresponding to the amount of light detected by the optical sensor

Including;

The drive control unit,

A voltage comparison unit comparing a plurality of preset reference voltages with the analog voltage signal and 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;

Fine adjustment unit for the user to fine-tune the brightness of the display panel step by step;

A memory in which data corresponding to a gamma characteristic curve for each sensor mode corresponding to the specific address and a gamma characteristic curve for each user mode corresponding to an adjustment amount of the fine control unit are stored; And

A gamma correction circuit for outputting a gamma corrected output signal according to each of the pre-stored gamma characteristic curves in response to a specific address output from the encoder or the user's selection

Characterized in that it comprises a.

On the other hand, as a means for achieving the above object, the gamma correction method according to the present invention,

a) selecting a driving mode for gamma correction of the display;

b) when the driving mode is a sensor mode, performing gamma correction according to a correction characteristic curve obtained according to an operation of an optical sensor in consideration of ambient brightness; And

c) performing gamma correction according to a correction characteristic curve corresponding to a corresponding level selected by a user when the driving mode is a user mode;

Characterized in that it comprises a.

Here, after the gamma correction according to the operation of the optical sensor of step b), the user may further comprise the step of performing a fine-tuned gamma correction by directly selecting the level.

Here, step b),

Detecting, by the optical sensor, an analog voltage corresponding to the amount of light;

Comparing a plurality of preset reference voltages with the analog voltage signal, and outputting a plurality of voltage levels respectively corresponding to the magnitudes;

Converting and outputting the plurality of voltage levels to a specific address of N bits; And

Outputting a gamma-corrected output signal according to a pre-stored gamma characteristic curve corresponding to the specific address of the N bits;

It may include.

The sensor mode and the user mode may be selected by a command register in the driving integrated circuit.

In this case, the user mode may be directly selected by the user in a switch method.

Here, the sensor mode may include a night mode, a dark in door, an in door, or an outdoor door luminance mode that is automatically set according to the ambient brightness. The luminance mode set to may include a plurality of gamma luminance levels finely adjusted by the user.

On the other hand, as a means for achieving the above object, the gamma correction method according to the present invention,

a) selecting a user mode for gamma correction of the display;

b) a user directly selecting a level among a plurality of preset levels;

c) reading a correction characteristic curve corresponding to the corresponding level from a memory; And

d) performing gamma correction according to the read correction characteristic curve

Characterized in that it comprises a.

The user mode may be selected by a command register in the driving integrated circuit.

Here, the user mode is characterized in that the user directly selects the corresponding level corresponding to the gamma characteristic curve in a switch method.

According to the present invention, the user may select a plurality of fine gamma corrections provided for each sensor mode or user mode, and thus the user may arbitrarily adjust the display brightness.

Hereinafter, a gamma correction apparatus and a method of a light emitting display device according to an exemplary 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.

On the other hand, in most imaging devices (imaging tube, CCD, MOS, etc.), the photoelectric conversion characteristic of incident light has a linear (gamma = 1.0) characteristic, but the total light conversion characteristic of a CRT, LCD, or organic EL light emitting display device is nonlinear (gamma). = 2.2) 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 corresponding addresses 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. Such gamma correction devices have picture adjustment inputs that allow the color, brightness and tint of an image to be adjusted.

4 is a schematic configuration diagram of a gamma correction apparatus of a light emitting display device according to an embodiment of the present invention, and FIG. 5 is a detailed configuration diagram of a gamma correction apparatus of a light emitting display device according to an embodiment of the present invention. A gamma correction apparatus of a light emitting display device according to an exemplary embodiment of the present invention includes a voltage comparator 710, an encoder 720, a gamma correction table 730, a gamma correction circuit 740, and a fine adjustment unit 750. It includes an integrated circuit 700 and an optical sensor 800, and each gamma luminance level (e.g., ten) for each luminance mode (e.g., four) so that the user can arbitrarily adjust the brightness. By providing, the user can freely select and also use four steps when substantially in sensor mode or user mode, but fine adjustment of each step is user selectable.

4 and 5, 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 compares the plurality of reference voltages Vref that are variably set according to the power supply voltage Vcc and the analog voltage signal AVout, and outputs a plurality of voltage levels respectively corresponding to the magnitudes thereof. do.

In this case, the voltage comparator 710 may include a reference voltage ( ^N ) between 2 ^N distribution resistors R1, R2, R3, and r4 connected in series with the variable power supply voltage Vcc, and a node of each 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, to adjust the voltage level. 2 ^N -1 comparators 711, 712, 713, and 714 to 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 power supply voltage Vcc connected to the voltage comparator 710 has a range of 2.7 to 5.5V, and typically may be 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 each of the previously stored gamma characteristic curves in response to a specific address output from the encoder 720 or the user's selection.

The memory 730 stores data corresponding to a gamma characteristic curve for each sensor mode corresponding to the specific address and a gamma characteristic curve for each user mode corresponding to an adjustment amount of the fine control unit, respectively. That is, the memory 730 stores data corresponding to the gamma characteristic curve in the form of a look-up table (LUT).

The fine control unit 750 is for the user to finely adjust the brightness of the display panel in stages, for example, it may be implemented by a switch method.

In addition, the sensor mode and the user mode may be selected by a command register in the driving integrated circuit, and the sensor mode may be directly selected by the user after four levels of gamma correction according to the operation of the optical sensor. One of the levels can be selected to perform fine-tuned gamma correction.

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.

FIG. 6 is a table illustrating luminance modes for each stage according to an exemplary embodiment of the present invention, wherein a sensor mode is automatically set according to a specific address “00, 01, 10, 11” output from the above-described encoder according to ambient brightness. Night, Dark in Door, In Door or Out Door luminance mode, the automatically set luminance mode is a multi-level gamma luminance level finely adjusted by the user, respectively It will include. That is, after gamma correction according to the operation of the optical sensor, the user may directly select a level to perform finely adjusted gamma correction. For example, when the specific address is "00", the luminance mode is Night, and then, a user may select a gamma luminance level of 1, 2, or 3 levels, and the gamma corresponding thereto. Gamma correction is made according to the characteristic curve.

7 is a flowchart illustrating a gamma correction method of a light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 7, in the gamma correction method according to an exemplary embodiment of the present invention, first, a gamma correction of a light emitting display device is determined (S710), and a driving mode for gamma correction of a display is selected (S720). ).

In this case, when the driving mode is the sensor mode, gamma correction is performed according to a correction characteristic curve obtained according to the operation of the optical sensor in consideration of the ambient brightness. Specifically, the optical sensor detects an analog voltage corresponding to the amount of light. (S730), the plurality of preset reference voltages are compared with the analog voltage signal, and a plurality of voltage levels corresponding to the magnitudes are output (S740). Next, the plurality of voltage levels are identified by N bits. The data is converted to an address and output (S750). Thereafter, a gamma-corrected output signal is output according to a pre-stored gamma characteristic curve corresponding to the specific address of N bits.

If the driving mode is the user mode, the user selects using the direct switch irrespective of the orphan sensor (S760), and then performs gamma correction according to the correction characteristic curve corresponding to the level selected by the user. Done.

The sensor mode includes a night mode, a dark in door, an indoor door, or an outdoor door brightness mode that is automatically set according to the ambient brightness. Each includes a plurality of gamma luminance levels finely adjusted by the user. That is, after gamma correction according to the operation of the optical sensor, the user may directly select a level to perform finely adjusted gamma correction.

Subsequently, after the above-described step S750 or S760, the luminance mode level according to the driving mode is selected (S770). If the first step, for example, is adjusted to four levels, and thus stored gamma The gamma correction is performed according to the characteristic curve (S780), or if the second step is adjusted to, for example, 10 levels, and thus the gamma correction is performed according to the stored gamma characteristic curve (S790).

As a result, in an embodiment of the present invention, by providing a plurality of gamma luminance levels (for example, ten) for each luminance mode (for example, four) so that the user can arbitrarily adjust the brightness, It is freely selectable and also uses four steps when in substantially sensor or user mode, but the ten fine adjustments in each step are user selectable.

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, the user may select a plurality of fine gamma corrections provided for each sensor mode or user mode, and thus the user may arbitrarily adjust the display brightness.

Claims (16)

In the gamma correction device of a light emitting display device, An optical sensor for outputting an analog voltage signal AVout corresponding to the detected external light amount; A voltage comparison unit comparing a plurality of preset reference voltages Vref with the analog voltage signal AVout and outputting a plurality of voltage levels corresponding to the magnitudes of the plurality of reference voltages Vref; An encoder for converting and outputting a plurality of voltage levels output from the voltage comparator to a specific address of N bits; Fine adjustment unit for the user to fine-tune the brightness of the display panel step by step; A memory in which data corresponding to a gamma characteristic curve for each sensor mode corresponding to the specific address and a gamma characteristic curve for each user mode corresponding to an adjustment amount of the fine control unit are stored; And A gamma correction circuit for outputting a gamma-corrected output signal according to each of the previously stored gamma characteristic curves in response to a specific address output from the encoder or the user's selection Gamma correction device comprising a. The method of claim 1, And the memory stores data corresponding to each of the gamma characteristic curves in the form of a look-up table (LUT). The method of claim 1, And the sensor mode and the user mode are selected by a command register in a driving integrated circuit. The method of claim 1, The sensor mode is a gamma correction device, characterized in that after the gamma correction according to the operation of the optical sensor, the user can directly select the level to perform a finely adjusted gamma correction. The method of claim 1, And the user mode comprises a switch for a user to directly select a level. 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; A scan driver for sequentially applying a selection signal to the plurality of scan lines, respectively; A data driver for applying a data voltage corresponding to an image signal to each pixel selected by the plurality of scan lines; An optical sensor for detecting an external light amount and outputting an analog voltage signal corresponding to the light amount; And  A driving controller which drives the data driver and the scan driver and performs gamma correction according to a pre-stored gamma characteristic curve corresponding to the amount of light detected by the optical sensor Including; The drive control unit, A voltage comparison unit comparing a plurality of preset reference voltages with the analog voltage signal and 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; Fine adjustment unit for the user to fine-tune the brightness of the display panel step by step; A memory in which data corresponding to a gamma characteristic curve for each sensor mode corresponding to the specific address and a gamma characteristic curve for each user mode corresponding to an adjustment amount of the fine control unit are stored; And A gamma correction circuit for outputting a gamma-corrected output signal according to each of the previously stored gamma characteristic curves in response to a specific address output from the encoder or the user's selection Light emitting display device comprising a. In the method for correcting the gamma characteristics of the light emitting display device, a) selecting a driving mode for gamma correction of the display; b) when the driving mode is a sensor mode, performing gamma correction according to a correction characteristic curve obtained according to an operation of an optical sensor in consideration of ambient brightness; And c) performing gamma correction according to a correction characteristic curve corresponding to a corresponding level selected by a user when the driving mode is a user mode; Gamma correction method comprising a. The method of claim 7, wherein And after gamma correction according to the operation of the optical sensor of step b), the user directly selecting a level to perform fine-tuned gamma correction. The method of claim 7, wherein step b), Detecting, by the optical sensor, an analog voltage corresponding to the amount of light; Comparing a plurality of preset reference voltages with the analog voltage signal, and outputting a plurality of voltage levels respectively corresponding to the magnitudes; Converting and outputting the plurality of voltage levels to a specific address of N bits; And Outputting a gamma-corrected output signal according to a pre-stored gamma characteristic curve corresponding to the specific address of the N bits; Gamma correction method comprising a. The method of claim 7, wherein And the sensor mode and the user mode are selected by a command register in a driving integrated circuit. The method of claim 7, wherein The user mode is gamma correction method characterized in that the user directly selects the level by a switch method. The method of claim 7, wherein The sensor mode includes a gamma correction mode including a night, dark in door, in door, or outdoor door brightness mode that is automatically set according to ambient brightness. The method of claim 12, The automatically set luminance mode comprises a gamma luminance level of a plurality of steps each user finely adjusted. In the method for correcting the gamma characteristics of the light emitting display device, a) selecting a user mode for gamma correction of the display; b) a user directly selecting a level among a plurality of preset levels; c) reading a correction characteristic curve corresponding to the corresponding level from a memory; And d) performing gamma correction according to the read correction characteristic curve Gamma correction method comprising a. The method of claim 14, And the user mode is selected by a command register in a driving integrated circuit. The method of claim 14, The user mode is gamma correction method characterized in that the user directly selects the corresponding level corresponding to the gamma characteristic curve in a switch method.

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