KR100592288B1 - Organic electroluminescent display device - Google Patents

Abstract

An object of the present invention is to provide an organic electroluminescent display device capable of varying the output brightness of a panel at an appropriate period according to an external condition detected by an external condition detecting sensor. In order to achieve the above object, the present invention provides an external condition detection unit for detecting an external condition to generate external condition data corresponding to the external condition; A vertical synchronous counter for receiving and counting a vertical synchronous signal to calculate a frequency of the vertical synchronous signal, and generating a sampling signal for each period determined by the frequency of the vertical synchronous signal; A gamma control register storing gamma control data indicating an output luminance distribution of the image data; A gamma selecting unit which calls an address of a gamma control register corresponding to the external condition data each time the sampling signal is received; And a data driver converting a digital image data signal into an analog image data signal according to the output luminance distribution represented by the gamma control data and outputting the analog image data signal to a data line of the organic electroluminescent panel.

Description

Organic electroluminescent display device

1 is a perspective view of a portable terminal having a conventional external condition detection unit.

2 is a partial cross-sectional view of an example of an external condition detection unit.

3 is a conceptual diagram of an organic electroluminescent device.

4 is a schematic plan view of an organic electroluminescent display device according to an embodiment of the present invention.

5 is a block diagram of an organic electroluminescent display device according to an embodiment of the present invention.

6 is a table illustrating a relationship between a frequency variable and a sampling period according to an embodiment of the present invention.

7 is a diagram for adjusting a level of a gamma curve of an organic electroluminescent display device according to an embodiment of the present invention.

8 is a diagram for reducing power consumption of an organic electroluminescent display device according to an embodiment of the present invention.

<Description of the symbols in the main part of the drawing>

400: organic electroluminescent display device

410: display panel

510: external condition detection unit

511: external condition sensor

512: A / D conversion unit

520: vertical synchronization counter

530: gamma control register

540: gamma selection unit

550: data driver

The present invention relates to an organic electroluminescent display device, and more particularly, to an organic electroluminescent display device capable of varying an output luminance of a panel according to an external condition detected by an external condition detection sensor.

In general, a flat panel display device is a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an organic electroluminescent display (electro-luminescent display) ELD) and the like, and have excellent characteristics such as thinness, light weight, and low power consumption. Such flat panel display devices are display devices for various electronic devices, such as mobile phones, personal digital assistants (PDAs), notebook computers, cameras, camcorders, etc., which are widely used by the general public in accordance with the development of electric, electronic, semiconductor, and information communication fields. As research and development.

Recently, TFT LCD displays using thin film transistors (hereinafter referred to as TFTs) have been used in various electronic information devices. Among them, portable information devices such as mobile phones, PDAs and PDA phones are equipped with various functions such as high resolution screen display, high quality sound output, various memory functions, dictionary functions, recording functions, and shooting functions according to various demands of consumers. . Accordingly, today's electronic information devices require a low power consumption environment along with a large battery usage environment so that various functions can be used for a long time while being portable.

1 is a perspective view of a portable terminal having a conventional external condition detection unit.

Referring to FIG. 1, the portable terminal 100 includes a liquid crystal display 104 and an external condition detector 200 disposed in the first body 102. The liquid crystal display 104 basically consists of a liquid crystal panel 106 and a backlight (not shown). The mobile terminal 100 includes a liquid crystal display driver 108 for driving the liquid crystal display device 104. The liquid crystal display driver 108 is shown to be disposed inside the first body 102. The mobile terminal 100 includes an antenna, a second body 110 on which a radio frequency (RF) processor (not shown) and a baseband processor (not shown) are disposed. The first body 102 and the second body 110 are hinged on the opposite side. The baseband processor includes a processor (not shown) for controlling the entire portable terminal 100.

The conventional portable terminal 100 adjusts the brightness by selecting an appropriate brightness level for the backlight of the liquid crystal display device 104 according to the signal sensed by the external condition detection unit 200. For example, some or all of the backlight is turned on or turned off.

As a publication disclosed in this concept, Korean Patent Laid-Open Publication No. 2003-0004552 discloses that the output brightness of an organic electroluminescent panel can be adjusted using a photo sensor.

Further, Japanese Laid-Open Patent Publication No. 2003-308046 discloses a display device having a brightness control unit for detecting an environment of a light emitting unit and adjusting the light emission intensity of each pixel according to the environment. In the above publication, in addition to the conventional organic electroluminescent element, another organic electroluminescent element is provided as part of the pixel as a sensor.

Meanwhile, an organic electroluminescent display device or a portable terminal equipped with an organic electroluminescent display device needs to adjust the output luminance according to an external environment, for example, illuminance, color temperature, heat temperature, and time of external light. In order to provide visibility that is suitable for the naked eye of the user, it is desirable to increase the output brightness of the panel in a bright place or time and to lower the output brightness of the panel in a dark place or a time.

However, when the external environment conditions, that is, the illuminance, color temperature, heat temperature, etc. of the external light suddenly change, if the output brightness of the panel changes at every instant of the sudden change, the user's visibility is rather adversely affected and the user's naked eye Can come. Furthermore, the lifespan of the organic electroluminescent device may be shortened and power consumption may be increased due to the rapidly changing output brightness change.

Therefore, there is a need for a means for sampling external conditions at appropriate intervals so as to reduce power consumption of the organic electroluminescent display device and at the same time provide comfort to the human eye.

The present invention is to solve the problems of the prior art and other problems, the object of the present invention is to sample the conditions of the surrounding environment at an appropriate period without the discomfort of the user's naked eye, and to change the output brightness according to the sampled conditions An electroluminescent display device is provided.

Another object of the present invention is to provide an organic electroluminescent display device that can extend the lifespan and lower the power consumption of an organic electroluminescent device by sampling the conditions of the surrounding environment at appropriate periods and changing the output luminance according to the sampled conditions. .

In order to achieve the above object, according to an aspect of the present invention, an external condition detection unit for detecting an external condition to generate external condition data (E) corresponding to the external condition;

A vertical synchronizing counter for receiving and counting a vertical synchronizing signal to calculate a frequency of the vertical synchronizing signal, and generating a sampling signal S for each period T determined by the frequency of the vertical synchronizing signal;

A gamma control register storing gamma control data indicating an output luminance distribution of the image data;

A gamma selecting unit which calls an address of a gamma control register corresponding to the external condition data E each time the sampling signal S is input; And

An organic electroluminescent display device includes a data driver converting a digital image data signal into an analog image data signal according to the output luminance distribution represented by the gamma control data and outputting the analog image data signal to a data line of the organic electroluminescent panel.

According to the organic electroluminescent display device according to the present invention, the external condition detection unit detects a change in the illuminance of the surrounding environment, it is possible to automatically reduce the brightness in a dark place or indoors to reduce unnecessary power consumption of the display device. In addition, the external conditions are sampled at appropriate intervals so that the user's eyes are not uncomfortable and visibility is improved, thereby increasing the lifespan and reducing power consumption of the organic EL device.

In the organic electroluminescent display device according to the present invention, the vertical synchronization counter receives a predetermined frequency variable (N), and the frequency variable (N) is divided by the frequency (f (Vsync)) of the vertical synchronization signal. The sampling signal S may be generated using a true value as the period T.

In the organic electroluminescent display device according to the present invention, the data driver receives the gamma control data from the gamma control register, generates a gray voltage corresponding to the output luminance distribution of the digital image data, and applies the gray voltage to the gray voltage. Accordingly, the digital image data may be converted into an analog data signal and output to the data line.

In the organic electroluminescent display device according to the present invention, the external condition detecting unit, an external condition detecting sensor for detecting an external condition and outputs an external condition analog signal (e) corresponding to the external condition; And a converter for converting the external condition analog signal into an external condition digital signal (E).

In a preferred embodiment, the data driver may adjust the data signal by adjusting the level of the gamma curve step by step according to the digital signal. The data signal includes a data voltage.

The gamma curve is a white gamma curve, and the gamma curve may include individual gamma curves of red, green, and blue.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. However, the present invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein.

2 is a partial cross-sectional view of an example of an external condition detection unit that may be used in the organic electroluminescent display device according to the present invention.

2 is a photo sensor that can be used as one of the external condition detection sensor. The photosensor 200 may be formed of a complementary metal oxide semiconductor (CMOS) photosensor as shown in FIG. 2. The photosensor 200 includes a silicon substrate 202, a P-type well 204 disposed on the silicon substrate 202, and an N-type region 210 formed on the P-type well 204. And an insulating layer 208 surrounding the N-type region 210. The N-type region 210 refers to a region doped with N-type impurities. A channel 206 formed by a PN junction is formed between the N-type region 210 and the P-type well 204. The insulating layer 208 is used to separate the N-type region 210 from other electrical elements to prevent shorting with other elements. When the photosensor 200 receives light, the electrons in the N-type region 210 near the channel 206 and the resistance of the channel decreases, so that between the P-type well 204 and the N-type region 210. As the current flows, the current or voltage between both ends changes.

In the organic electroluminescent display device according to the present invention, the resistance of the channel is reduced so that current flows between both ends of the P-type well 204 and the N-type region 210 to change the current or voltage between the external condition analog signals. (e) is used.

On the other hand, the organic electroluminescent display device using the organic electroluminescent element is recently attracting attention as one of the next generation display device. This is because the organic electroluminescent device emits light in all regions of visible light including blue, and has advantages such as high brightness and low operating voltage characteristics. Such an organic electroluminescent device will be described below.

3 is a conceptual diagram of an organic electroluminescent device. Referring to FIG. 3, the organic electroluminescent device 300 may include a glass substrate 302, an anode electrode 304, a hole transport layer (HTL) 306, an emission layer 308, an electron transport layer; An ETL 310, and a cathode electrode 312. The anode electrode 304 and the cathode electrode 312 are each formed of a transparent electrode such as an indium tin oxide (ITO) electrode or a metal electrode such as aluminum (Al) according to a top emission, a bottom emission, or a double-sided emission method. The organic electroluminescent device 300 has an electron injecting layer (EIL), a hole injecting layer (HIL), or a hole blocking layer (hole) in order to improve the luminous efficiency by improving the injection characteristics of electrons and holes. It may be made of a multi-layer structure further comprising a blocking layer (HBL). The organic electroluminescent device 300 is a light emitting device, and emits light in proportion to a current flowing into the device. At this time, the light emitted from the organic electroluminescent device 300 is propagated in the radial direction.

4 is a schematic plan view of an organic electroluminescent display device according to an embodiment of the present invention.

Referring to FIG. 4, the organic electroluminescent display device 400 includes an organic electroluminescent display panel 410 and an external condition detector 510. The organic electroluminescent display panel 410 basically includes a plurality of organic electroluminescent elements (not shown) constituting each pixel or subpixel. In an embodiment, the external condition detecting unit 510 may be a photosensor, and in this case, the external condition detecting unit 510 may be located in a region 420p separated from the organic electroluminescent display panel 410 and exit from the organic electroluminescent display panel 410. It is preferable to prevent light from flowing into the external condition detection unit 510.

5 is a block diagram of an organic electroluminescent display device according to an embodiment of the present invention. The organic electroluminescent display device according to the exemplary embodiment of the present invention includes an external condition detector 510, a vertical synchronization counter 520, a gamma selector 540, a gamma control register 530, a data driver 550, and an organic electric field. The light emitting panel 410 is included.

The external condition detecting unit 510 detects an external condition and generates external condition data E corresponding to the external condition. The external condition detecting unit 510 may include an external condition detecting sensor 511 and an A / D converter 512 for detecting an external condition. The external condition detection unit 510 includes various types of sensors capable of detecting ambient illumination. For example, the external condition detecting sensor 511 includes a charge coupling device, a charge injection device, a photomultiplier tube, a photodiode, a spectroradiometer, a CMOS optical device, and the like. The external condition sensor 511 detects the ambient brightness of the organic electroluminescent display device 500. For example, the external condition sensor 511 senses external light by external incident light energy to sense a voltage or current signal generated in the device. This voltage value or current value is an external condition analog signal e corresponding to the external condition.

The A / D converter 512 converts the external condition analog signal e into an external condition digital signal E. Since the external condition digital signal E is a signal representing the detected external condition, a larger number of bits is advantageous for detecting various sampling values.

The external condition data E detected by the external condition detector 510 is transmitted to the gamma selector 540.

On the other hand, in the organic electroluminescent display device according to the present invention, the vertical synchronization counter 520 causes the gamma selection unit 540 to change the gamma value every appropriate period. Specifically, the vertical synchronization counter 520 receives the vertical synchronization signal Vsync, counts the vertical synchronization signal Vsync with a high-speed system clock CK, and calculates the frequency of the vertical synchronization signal Vsync. . The vertical synchronization counter 520 generates a sampling signal S for each period T determined by the frequency f (Vsync) of the vertical synchronization signal Vsync and outputs the sampling signal S to the gamma selection unit 540.

In general, since the vertical synchronization signal (Vsync) is 60Hz in the NTSC system and the vertical synchronization signal (Vsync) is 50Hz in the PAL system, the periods are 1/60 sec and 1/50 sec, respectively.

The vertical synchronization counter 520 receives a predetermined frequency variable N and sets the frequency T divided by the frequency f (Vsync) of the vertical synchronization signal as the period T. The sampling signal S can be generated. In other words, the vertical synchronization counter 520 generates the sampling signal S for each appropriate period T (s), which is obtained by multiplying the period T (Vsync) of the vertical synchronization signal Vsync by a value N of a predetermined value. Output to the gamma selector 540. At this time, a value N of a predetermined value should be determined in order to determine the period T (s), which may be given by a manufacturer or a user.

In an embodiment, the period T (s) at which the sampling signal S is generated may be as shown in Equation 1 below.

T (S) = N * T (Vsync) = N / f (Vsync)

For example, if f (Vsync), which is a period of Vsync, is 60 Hz and the frequency variable N is 120, the sampling signal S is generated every two seconds, and the gamma selection unit 540 generates the sampling signal S. ), The gamma control register 530 is commanded to transmit the gamma control data to the data driver 550 once every two seconds.

6 is a table showing a relationship between a frequency variable and a sampling period according to an embodiment of the present invention.

For example, when a 000 _(bit) value is input to the vertical synchronization counter 520, the frequency variable N corresponding thereto is 1, and thus the vertical synchronization counter 520 has a frequency variable 1 equal to the vertical synchronization frequency f (Vsync). The sampling signal S can be generated for every 1 / (f (Vsync)) with the value divided by) as the sampling period T. In addition, for example, when a value of 110 _(bit) is input to the vertical synchronization counter 520, the frequency variable N corresponding thereto is 64. Therefore, the vertical synchronization counter 520 has a vertical synchronization frequency f ( The sampling signal S can be generated every 64 / (f (Vsync)) using the value divided by Vsync) as the sampling period T. In addition, for example, when the value 111 _(bit) is input to the vertical synchronization counter 520, the frequency variable N corresponding thereto is 128, so that the vertical synchronization counter 520 has a vertical synchronization frequency f ( The sampling signal S can be generated every 128 / (f (Vsync)) using the value divided by Vsync) as the sampling period T.

The gamma control register 530 is a memory in which gamma control data indicating an output luminance distribution of image data is stored. Whenever the sampling signal S is input, the gamma selection unit 540 calls the address A of the gamma control register corresponding to the external condition data E. In this case, the gamma control data stored at the called address A is output to the data driver 550, and the data driver 550 converts the digital image data signal into an analog image data signal according to the output luminance distribution indicated by the gamma control data. It converts and outputs to the data line of an organic electroluminescent panel.

In one embodiment, as shown in FIG. 5, four register sets are provided in the gamma control register, and the gamma selection unit 540 is provided from the external condition detection unit 510 every predetermined period T (s). According to the external condition data E, the addresses A of the four gamma control register sets can be called. For example, when the address A is 00, the gamma control data 0 is output to the data driver 550. When the address A is 01, the gamma control data 1 is 10 and the address A is 10. In this case, the gamma control data 2 may be output, the gamma control data 1 may be output when the address A is 01, and the gamma control data 3 may be output when the address A is 11.

The gamma control data includes levels of a plurality of gamma curves corresponding to external condition data. The levels of the plurality of gamma curves correspond to the plurality of white levels or the black levels displayed on the organic electroluminescent display panel 410, respectively.

The data driver 550 receives gamma control data from the gamma control register 530 every period T (s), generates a gray voltage corresponding to the output luminance distribution of the digital image data, and applies the gray voltage to the gray voltage. Accordingly, the digital image data is converted into an analog data signal and output to the data line connected to the organic electroluminescent panel 410.

The organic electroluminescent display device may include a scan driver (not shown) in addition to the data driver. In this case, the data driver 410 and the scan driver are formed to matrix drive the organic electroluminescent display panel 410. The data driver 410 and the scan driver may be disposed on a glass substrate of the organic electroluminescent display panel 410 in a chip on glass manner. In the organic electroluminescent display panel 410, the plurality of organic electroluminescent elements may be arranged in a matrix form, and a plurality of data lines and a plurality of scan lines may be alternately disposed between the plurality of organic electroluminescent elements.

As described above, according to the organic electroluminescent display device according to the present invention, visibility can be greatly improved according to the condition of the external environment of the display device, for example, a change in ambient illuminance. Furthermore, since the output luminance can be adjusted according to external conditions, the lifespan of the organic electroluminescent device can be extended and the power consumption of the display device can be relatively reduced.

For example, as shown in FIG. 7, the present invention is made such that the luminance according to the gamma curve A is displayed on the display panel in a dark place, and the luminance according to the gamma curve B is displayed on the display panel in a bright place. In particular, in adjusting the level of the gamma curve, the present invention utilizes a sensing signal of a photo sensor in which a change in illuminance of the surrounding environment is more accurately sensed.

Therefore, according to the present invention, an organic electroluminescent display device in which luminance is more precisely and accurately adjusted can be provided. Furthermore, according to the present invention, as shown in FIG. 8, the brightness of the organic electroluminescent display device is automatically adjusted as shown by reference E using a photo sensor that detects a change in ambient illumination at night, in a dark place, or indoors. By adjusting, the power consumption of the display device can be reduced by the shaded area C, as compared with the case where the luminance is not automatically adjusted as indicated by reference numeral D. FIG.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the organic electroluminescent display device according to the present invention as described above has the following effects.

First, after setting the gamma control register corresponding to the external condition data, the external condition sensor generates the external condition data according to the brightness of the surrounding environment and the luminance of the organic electroluminescent display device according to the corresponding gamma control register data. By adjusting, there is an effect that the visibility of the display device can be greatly improved.

Second, the external condition detection unit detects a change in the illuminance of the surrounding environment, and automatically lowers the luminance in a dark place or a room, thereby contributing to the long life of the organic electroluminescent device and reducing unnecessary power consumption of the display device. have.

Third, the organic electroluminescent display device according to the present invention samples external conditions at appropriate intervals. Since the output luminance changes each time the vertical synchronization counter outputs the sampling signal S, which is a sampling signal, there is no discomfort to the user's eyes and the visibility is improved.

The invention is not limited to the examples described above and represented in the drawings. Those skilled in the art taught by the above-described embodiments, many modifications to the above-described embodiments are possible by substitution, erasure, merging, etc. within the scope and object of the present invention described in the following claims.

Claims (4)

An external condition detector for detecting an external condition and generating external condition data corresponding to the external condition; A vertical synchronous counter for receiving and counting a vertical synchronous signal to calculate a frequency of the vertical synchronous signal, and generating a sampling signal for each period determined by the frequency of the vertical synchronous signal; A gamma control register storing gamma control data indicating an output luminance distribution of the image data; A gamma selecting unit which calls an address of a gamma control register corresponding to the external condition data each time the sampling signal is received; And A data driver converting a digital image data signal into an analog image data signal according to the output luminance distribution indicated by the gamma control data and outputting the analog image data signal to a data line of an organic light emitting panel; Organic electroluminescent display device comprising a. The method of claim 1, And the vertical synchronous counter receives a predetermined frequency variable and generates the sampling signal based on a period of which the frequency variable is divided by the frequency of the vertical synchronous signal. The method of claim 1, The data driver receives the gamma control data from the gamma control register, generates a gray voltage corresponding to an output luminance distribution of the digital image data, and converts the digital image data into an analog data signal according to the gray voltage. And output the data lines to the data line. The method of claim 1, The external condition detecting unit may include: an external condition detecting sensor configured to detect an external condition and output an external condition analog signal corresponding to the external condition; And And an converter for converting the external condition analog signal into an external condition digital signal.

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