KR100592286B1 - 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, an external condition detection unit for detecting an external condition to generate external condition data corresponding to the external condition; A sampling signal when the first register storing the external condition data, the second register receiving the data of the first register, and the external condition data stored in the first register and the external condition data stored in the second register are the same A sampling unit including a logic gate for outputting a; 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 circuit diagram illustrating an example of a circuit included in the sampling unit of FIG. 5.

FIG. 7 is a circuit diagram illustrating an example embodiment of a circuit included in the sampling unit of FIG. 5.

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

9 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.

FIG. 10 is a diagram for reducing power consumption of an organic electroluminescent display device according to an embodiment of the present invention. FIG.

<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: sampling unit

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 a flat panel display device is a display device of various electronic devices such as mobile phones, personal digital assistants (PDAs), notebook computers, cameras, camcorders, etc., which are widely distributed to the general public in accordance with the development of electric, electronic, semiconductor, and information communication fields. 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) that controls 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 first register M1 storing the external condition data E, a second register M2 receiving the data of the first register, and external condition data stored in the first register and stored in the second register A sampling unit including a logic gate for outputting a sampling signal S when the external condition data is the same;

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 sampling unit receives a predetermined frequency variable (N), and the external condition data stored in the first register and the external condition data stored in the second register are continuously the frequency. When the same as the variable can be output the sampling signal. In this case, the sampling unit, the external condition data stored in the first register and the external condition data stored in the second register counts the same value, the external condition data stored in the first register and the external condition stored in the second register The count may be cleared if the data are not consecutively identical.

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 organic electroluminescent devices emit light in all regions of visible light including blue, and have 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 sampling unit 520, a gamma selector 540, a gamma control register 530, a data driver 550, and an organic electroluminescence. Panel 410.

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 transferred to the sampling unit 520.

In the organic electroluminescent display device according to the present invention, the sampling unit 520 transmits the sampling signal S at appropriate intervals, so that the external condition data is received whenever the gamma selection unit 540 receives the sampling signal S. The gamma register data of the gamma control register 530 corresponding to (E) is selected. Specifically, the sampling unit 520 includes a first register M1 and a second register M2 capable of temporarily storing the external condition data E, and store the data stored in the first register and the second register. When the data are continuously the same, the sampling signal S can be output.

FIG. 6 is a circuit diagram illustrating an example of a circuit included in the sampling unit of FIG. 5, and outputs a sampling signal S when the data stored in the first register and the data stored in the second register are continuously identical. Indicates.

6 illustrates a connection structure of registers in which data is serially input and shifted. Assuming that the external condition data is composed of 8-bit signals, when eight clock pulses CP are input, the first external condition data of 8 bits is sequentially shifted and stored in the first register M1 on the left side. . After the eight clock pulses CP are input again, the first external condition data stored in the first register M1 on the left side is sequentially moved to the second register M2 on the right side, and the first register on the left side is moved. In M1, new 8-bit external condition data is shifted and stored. In this order, each time eight clock pulses CP are applied, 8-bit external condition data E is input from the external condition detecting unit 510 into the first register M1, and the first register M1 is applied. The previous external condition data E stored in the memory moves to the second register M2.

6 shows a logic gate combination for comparing the flip-flops FF11 to FF18 of the first register M1 and the output signals of the flip-flops FF21 to FF28 of the second register M2, respectively. The logic gate combination compares each flip-flop FF11 to FF18 of the first register M1 with each flip-flop FF21 to FF28 of the second register M2 and turns on when the signals are all the same. ) Signal and an OFF signal if the signal is different. A first counter C1 for outputting one pulse per eight clocks is arranged in parallel with the logic gate combination. The output signal of the first counter C1 is applied to the input terminal of the AND gate together with the output of the logic gate combination, and the output terminal of the AND gate is connected to the enable terminal EN of the gamma selector 540. The signal output from the output terminal of the AND gate is used as the sampling signal (S).

Therefore, the circuit disclosed in FIG. 6 shifts the data of the first register M1 to the second register M2 every eight clock pulses, and stores the flip-flops FF11 to FF18 of the first register M1. When the bit data and the bit data stored in the flip-flops FF21 to FF28 of the second register M2 are compared with each other and all are the same, the sampling signal S is output. Accordingly, the sampling unit 520 outputs the sampling signal S when the data stored in the first register and the data stored in the second register are continuously the same.

6 illustrates an embodiment using a register of a serial input-parallel output method, but the first register and the first register may also be used using other registers of the serial input-serial output, parallel input-serial output, and parallel input-parallel output methods. Note that it is within the scope of the present invention as long as the data stored in the two registers are compared to output the sampling signal S when they are the same.

On the other hand, in the organic electroluminescent display device according to the present invention, the sampling unit 520 receives a predetermined frequency variable (N), the external condition data stored in the first register (M1) and the second register (M2) The sampling signal S may be output when the stored external condition data is continuously the same as the frequency variable N. FIG. For example, FIG. 7 is a circuit diagram illustrating an example of a circuit included in the sampling unit of FIG. 5, wherein a second counter C2 is interposed between the logic gate combination and the gamma selector 540. The second counter C2 counts the same number of times of the external condition data stored in the first register M1 and the external condition data stored in the second register M2, so that the sampling signal S becomes the frequency variable N. Outputs

The sampling unit 520 counts the same numerical value as the external condition data stored in the first register M1 and the external condition data stored in the second register M2, and the external condition data stored in the first register M1 and the first condition M are counted. If the external condition data stored in the two registers 2M are not identical in succession, the count may be cleared. The second counter C2 determines the count once every eight pulses by using the output signal of the first counter C1 as a clock signal. The second counter C2 counts each time the output signal of the first counter C1 is applied as a clock signal, and at the same time, external condition data stored in the first register M1 and stored in the second register 2M. If the external condition data is not the same continuously, the counter is initialized by applying an ON signal to the CLEAR stage.

As shown in FIG. 7, when the external condition data E stored in the two registers are equal to each other by the frequency variable N, the sampling period may be adjusted using a circuit in which the sampling signal S is output. At this time, a value N of a predetermined value should be determined to determine the period, which may be given by a manufacturer or a user.

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

For example, when a value of 001 _(bit) is input to the sampling unit 520, the frequency variable N corresponding thereto is 1, so that the sampling unit 520 is connected to the first register M1 and the second register M2. When the stored external condition data E are identical to each other once, a sampling signal S is output. In addition, for example, when a value of 100 _(bit) is input to the sampling unit 520, the frequency variable N corresponding thereto is 4, so that the sampling unit 520 includes the first register M1 and the second register M2. The sampling signal S is outputted when the external condition data E stored in the same is equal to four times. In addition, for example, when the value 111 _(bit) is input to the sampling unit 520, the frequency variable N corresponding thereto is 7. Therefore, the sampling unit 520 may include the first register M1 and the second register M2. Outputs the sampling signal S when the external condition data E stored in the &quot;

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. At this time, the gamma control data stored at the called address A is output to the data driver 550, and the data driver 550 outputs the digital image data signal according to the output luminance distribution indicated by the gamma control data. Is converted into the data line of the 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. 9, the present invention is configured 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. 10, the brightness of the organic electroluminescent display device is automatically adjusted as shown by the 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.

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. There is.

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 sampling unit 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 (5)

An external condition detector for detecting an external condition and generating external condition data corresponding to the external condition; A sampling signal when the first register storing the external condition data, the second register receiving the data of the first register, and the external condition data stored in the first register and the external condition data stored in the second register are the same A sampling unit including a logic gate for outputting a; 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, The sampling unit receives a predetermined frequency variable and outputs the sampling signal when the external condition data stored in the first register and the external condition data stored in the second register are continuously equal to the frequency variable. Organic electroluminescent display device. The method of claim 2, The sampling unit may count the same numerical value as the external condition data stored in the first register and the external condition data stored in the second register, and the external condition data stored in the first register and the external condition data stored in the second register may be counted. An organic electroluminescent display device, characterized in that the count is cleared if they are not identical continuously. 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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