JP2005227543A - Organic EL display device - Google Patents

Abstract

In an organic EL display device, when impulse-type display driving is performed in consideration of suppression of a change in luminance of a screen, light emission luminance is changed according to a change in a light emission period. However, in the organic EL element, when the emission luminance is increased, the deterioration of the emission luminance becomes extremely large.
An input signal motion detection unit that detects whether an input video signal is a moving image or a still image, and a drive control unit that controls a source driver, a write gate driver, and a lighting gate driver. When the input video signal is a moving image, the gain of the signal gain converter 101 is increased, and the light emission period within a predetermined period of the organic EL display device is driven. The lighting scanning signal driving period from the lighting gate driver 106 is controlled so as to be shortened.
[Selection] Figure 1

Description

  The present invention relates to an organic EL display device for the purpose of improving display quality.

  In recent years, organic EL display devices have attracted attention because of their features of being thin and having high image quality compared to other display devices. However, the organic EL display device positioned as high image quality also adopts a driving method similar to that of a conventional liquid crystal display device, and is a hold-type display similar to the liquid crystal display device, so that it is viewed from the viewpoint of moving image visibility. It can never be said to be high image quality.

  In a liquid crystal display device, there is an example in which an OCB liquid crystal that responds at a relatively high speed is employed to improve the visibility of moving images. A conventional liquid crystal display device driving method and liquid crystal display device will be described below.

FIG. 11 is a block diagram showing a configuration of a conventional liquid crystal display device. 11, the liquid crystal display device includes a line double speed conversion unit 701 to which a video signal and a synchronization signal are input, an input signal motion detection unit 702, a drive control unit 703, a source driver 704, a gate driver 705, a liquid crystal display unit 707, an opposing drive A unit 706, a backlight control unit 708, and a backlight 709. The liquid crystal display unit 707 includes pixels arranged in a matrix at intersections of source lines to which signals from the source driver 704 are supplied and gate lines to which scanning signals from the gate driver 705 are supplied. The pixel includes a liquid crystal and a switching element (TFT). FIG. 12 is a diagram showing the driving timing of the conventional liquid crystal display device. In FIG. 12, gate signals Vg (n−1), Vg (n), and Vg (n + 1) are supplied to the gate lines Xn−1, Xn, and Xn + 1, respectively. When the gate signal is in the Hi state, the corresponding gate line is turned on, and the source line signal is written to the pixels on the line. One frame period (1V) is divided into two periods P1 and P2, and a high level signal (black signal level) is written in the P1 period, and a signal corresponding to the video signal is written in the P2 period. In the OCB liquid crystal, it is necessary to consider the processing in the P1 period in order to prevent reverse transition, but since it is not directly related to the present invention, details are not mentioned here. As a display operation, a video display is displayed after black is displayed. The input signal motion detection unit 702 detects whether the video signal is a moving image or a still image. If the video signal is a moving image, the P1 period is longer than a predetermined length. If the video signal is a still image, the P1 period is set. The length is shorter than a predetermined length. Thereby, the display method is made closer to the impulse-type display from the hold-type display to improve the moving image visibility.
JP 2002-31790 A

  In an organic EL display device, when impulse-type display driving is performed in consideration of suppression of screen luminance change, the light emission luminance is changed according to the change in the light emission period. FIG. 13 shows the light emission luminance and the operation state of the light emission period in that case.

  However, in the organic EL element, there is a problem that when the light emission luminance is increased, the light emission luminance deterioration is extremely increased. FIG. 14 shows the luminance deterioration state of the organic EL element when the visual luminance is approximately the same value. The horizontal axis shows the light emission luminance and the light emission period (within a predetermined period), and shows the relationship in which the light emission luminance increases as the light emission period becomes shorter. The shorter the light emission period and the larger the light emission luminance, the greater the deterioration of the lifetime.

  Therefore, an object of the present invention is to provide a driving method of an organic EL display device and an organic EL display device that can improve the visibility of moving images and suppress the deterioration of life.

  In order to achieve the above object, an invention according to claim 1 of the present application is directed to an input signal motion detection unit that detects whether an input video signal is a moving image or a still image, and a gain of the video signal. A signal gain conversion unit to be changed, a plurality of source lines to which pixel data is supplied, a plurality of write gate lines to which a write scanning signal for pixels is supplied, and a plurality of lighting gates to which pixel lighting scanning signals are supplied An organic EL display unit in which organic EL pixel cells are arranged in a matrix corresponding to the intersection of the source line, the write gate line, and the lighting gate line, and a source driver that drives the source line A write gate driver for driving the write gate line, a lighting gate driver for driving the lighting gate line, the source driver and the write gate driver. An organic EL display device having a driver and a drive control unit for controlling the lighting gate driver, wherein when the input video signal is a moving image, the gain of the signal gain conversion unit is increased, and the organic EL display The lighting scanning signal driving period from the lighting gate driver is controlled so that the light emission period within a predetermined period of the device is shortened.

  According to a second aspect of the present invention, an input signal motion detection unit that detects whether an input video signal is a moving image or a still image, a plurality of source lines to which pixel data is supplied, and a pixel Corresponding to a plurality of write gate lines to which a write scan signal is supplied, a plurality of light gate lines to which a pixel scan signal is supplied, and a portion where the source line, the write gate line and the lighting gate line intersect. An organic EL display unit in which organic EL pixel cells are arranged in a matrix, a source driver that drives the source line, a write gate driver that drives the write gate line, and a lighting gate that drives the lighting gate line An organic EL display device having a driver, and a drive control unit that controls the source driver, the write gate driver, and the lighting gate driver When the input video signal is a moving image, the output signal gain of the source driver is increased, and the light emitting period from the lighting gate driver is shortened so that the light emission period within the predetermined period of the organic EL display device is shortened. The lighting scan signal driving period is controlled.

  According to a third aspect of the present invention, the source driver includes a D / A converter and changes the level of the output signal to the source line by a control signal.

  According to a fourth aspect of the present invention, when the input video signal is a moving image, the gain of the signal output to the source line and the predetermined period of the organic EL display device according to the magnitude of the motion The light emission period is controlled.

  The invention described in claim 5 is characterized in that when the signal gain and the light emission period are changed, control is performed so that the average luminance of the display screen does not change.

  According to a sixth aspect of the present invention, the driving of the lighting gate lines is controlled so that the lines are sequentially lit for a predetermined period after writing in synchronism with data writing to pixels in line units by the writing gate lines. It is characterized by doing.

  According to a seventh aspect of the present invention, a frequency converter that changes a frame frequency of an input video signal is provided, and a predetermined period after writing is synchronized with completion of data writing to pixels of all lines by the writing gate line. The driving of the lighting gate line is controlled so that all lines are turned on simultaneously.

  Further, the invention according to claim 8 is provided with an input signal peak detector for detecting a peak value of the input video signal, and when the input video signal is a moving image, according to the peak value of the video signal, The gain of the signal to the source line and the light emission period within a predetermined period in the organic EL display unit are controlled.

  According to the present invention, when an input video signal is displayed on a display unit configured by an organic EL element, it is possible to realize a display device that can improve the visibility of moving images and suppress the deterioration of life. .

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of an organic EL display device according to Embodiment 1 of the present invention. In FIG. 1, an input signal motion detection unit 102 detects whether an input video signal is a moving image or a still image. The signal gain conversion unit 101 changes the gain of the video signal according to the detection result of the input signal motion detection unit 102. The organic EL display unit 107 is connected to the source driver 104 by a plurality of source lines, connected to the write gate driver 105 by a plurality of write gate lines, and connected to the lighting gate driver 106 by a plurality of lighting gate lines. Further, in the organic EL display unit 107, organic EL pixel cells are arranged in a matrix corresponding to portions where the source line, the write gate line, and the lighting gate line intersect. The drive control unit 103 controls the driving of the source driver 104 and the write gate driver 105 and changes the driving timing of the lighting gate driver 106 according to the detection result of the input signal motion detection unit 102. The source driver 104 outputs pixel data to the source line in accordance with the video signal (Vs) from the signal gain converter 101. The write gate driver 103 outputs a write scan signal to the pixel to the write gate line. The lighting gate driver 106 outputs a lighting scanning signal to the lighting gate line. The pixel cell includes a plurality of switching elements (TFTs), holds pixel data of the source line in the pixel cell by a write scanning signal, and emits light with a luminance corresponding to the pixel data by a lighting operation signal.

  Hereinafter, the driving method according to the first embodiment of the present invention will be described with reference to FIG. In FIG. 2, (a) shows a pixel emission state at the time of still image detection. (B) shows the pixel emission state at the time of moving image detection. In both cases, the same level of brightness is assumed visually. In (a), the light emission luminance is small, and the light emission period within one frame period is long. In (b), the light emission luminance is large and the light emission period is short.

  (Aa) shows the signal state when the operation of (a) is performed. In the case of still image detection, the gain in the signal gain conversion unit 101 is set to be small, and the level of the output video signal (Vs) is small. The writing gate line (n line) is turned on for approximately one horizontal period (1H), and pixel data corresponding to the video signal (Vs) is written into the pixel cell. Since it is still image detection, the signal of the lighting gate line (n line) operates so that the light emission period within one frame period becomes long.

  (Bb) shows a signal state when the operation of (b) is performed. In the case of moving image detection, the gain in the signal gain converter 101 is set large, and the level of the output video signal (Vs) becomes large. Since it is a moving image detection, the signal of a lighting gate line (n line) operates so that the light emission period within one frame period becomes short.

  As described above, according to the present embodiment, when an input video signal is a moving image, moving image visibility can be improved by approaching impulse-type driving. Further, in the case of a still image, the life of the EL element can be reduced by bringing it closer to hold-type driving. Although the moving image detection determination is made based on a predetermined amount of movement, the light emission period and the light emission luminance may be changed according to the amount of movement.

(Embodiment 2)
FIG. 3 is a block diagram showing the configuration of the organic EL display device according to Embodiment 2 of the present invention. In FIG. 3, an input signal motion detection unit 201 detects whether an input video signal is a moving image or a still image. The organic EL display unit 206 is connected to the source driver 203 by a plurality of source lines, connected to the write gate driver 204 by a plurality of write gate lines, and connected to the lighting gate driver 205 by a plurality of lighting gate lines. Further, in the organic EL display unit 206, organic EL pixel cells are arranged in a matrix corresponding to portions where the source line, the writing gate line, and the lighting gate line intersect. The drive control unit 202 controls the drive of the write gate driver 204 and controls the output gain of the source driver 203 and the drive timing of the lighting gate driver 205 according to the detection result of the input signal motion detection unit 201. The source driver 203 changes pixel data output to the source line in accordance with a control signal from the drive control unit 202. The write gate driver 204 outputs a write scan signal to the pixel to the write gate line. The lighting gate driver 205 outputs a lighting scanning signal to the lighting gate line. The pixel cell includes a plurality of switching elements (TFTs), holds pixel data of the source line in the pixel cell by a write scanning signal, and emits light with a luminance corresponding to the pixel data by a lighting operation signal.

  Hereinafter, a driving method according to Embodiment 2 of the present invention will be described with reference to FIG. In FIG. 4, (c) shows the pixel emission state at the time of still image detection. (D) shows the pixel emission state at the time of moving image detection. In both cases, the same level of brightness is assumed visually. In (c), the light emission luminance is small, and the light emission period within one frame period is long. In (d), the light emission luminance is large and the light emission period is short.

  (Cc) indicates a signal state when the operation of (c) is performed. In the case of still image detection, the source driver current gain in the source driver 203 is set small, and the level of pixel data output to the source line is small. The writing gate line (n line) is turned on for approximately one horizontal period (1H), and pixel data corresponding to the video signal (Vs) is written into the pixel cell. Since it is still image detection, the signal of the lighting gate line (n line) operates so that the light emission period within one frame period becomes long.

  (Dd) indicates a signal state when the operation of (d) is performed. In the case of moving image detection, the source driver current gain in the source driver 203 is set to be large, and the level of pixel data output to the source line is large. Since it is a moving image detection, the signal of a lighting gate line (n line) operates so that the light emission period within one frame period becomes short.

  FIG. 5 shows an example of the internal configuration of the source driver. In FIG. 5, the signal holding unit holds a value corresponding to the video signal so as to correspond to the source line. The signal holding unit 207 includes a shift register circuit, a sample hold circuit, and the like. The D / A converter 208 outputs a reference voltage corresponding to the control signal. The level conversion unit 209 changes the output signal gain from the signal holding unit 207 according to the reference voltage, and outputs it to the source line. The output signal can be either a voltage level signal or a current level signal depending on the pixel cell configuration in the organic EL display section.

  As described above, according to the present embodiment, when an input video signal is a moving image, moving image visibility can be improved by approaching impulse-type driving. Further, in the case of a still image, the life of the EL element can be reduced by bringing it closer to hold-type driving. Since the gain change in the source driver is not a change in the gain of the video signal, the bit accuracy of the video signal can be ensured.

(Embodiment 3)
FIG. 6 is a block diagram showing a configuration of the organic EL display device according to Embodiment 3 of the present invention. In FIG. 6, a frequency converter 301 converts the frequency of the video signal. The input signal motion detection unit 302 detects whether the input video signal is a moving image or a still image. The organic EL display unit 307 is connected to the source driver 304 by a plurality of source lines, connected to the write gate driver 305 by a plurality of write gate lines, and connected to the lighting gate driver 306 by a plurality of lighting gate lines. Further, in the organic EL display unit 307, organic EL pixel cells are arranged in a matrix corresponding to portions where the source line, the writing gate line, and the lighting gate line intersect. The drive control unit 303 controls the drive of the write gate driver 305 and controls the output gain of the source driver 304 and the drive timing of the lighting gate driver 306 according to the detection result of the input signal motion detection unit 302. The source driver 304 changes pixel data output to the source line in accordance with a control signal from the drive control unit 303. The write gate driver 305 outputs a write scan signal to the pixel to the write gate line. The lighting gate driver 306 outputs a lighting scanning signal to the lighting gate line. The pixel cell includes a plurality of switching elements (TFTs), holds pixel data of the source line in the pixel cell by a write scanning signal, and emits light with a luminance corresponding to the pixel data by a lighting operation signal.

  Hereinafter, an example of the driving method according to Embodiment 3 of the present invention will be described with reference to FIG. In FIG. 7, the video signal that has been frequency-converted (speeded up) by the frequency converter 301 is converted into a video signal for three horizontal periods within the original one horizontal period (1H). As the write gate signal, a write scan signal corresponding to each original horizontal period is output. Since the speed is increased, the write operation for all lines is completed in the first half of one frame period (1 V). Thereafter, all the lines are turned on simultaneously by the lighting gate lines. The light emission period and the light emission luminance are controlled according to the movement of the video signal as in the second embodiment.

  As described above, according to the present embodiment, when an input video signal is a moving image, moving image visibility can be improved by approaching impulse-type driving. Further, as shown in FIG. 8, a driving method is also possible in which lighting scanning of the lighting gate lines is sequentially performed in synchronization with writing scanning in units of lines by the writing gate lines.

(Embodiment 4)
FIG. 9 is a block diagram showing the configuration of the organic EL display device according to Embodiment 4 of the present invention. In FIG. 9, an input signal motion detection unit 401 detects whether an input video signal is a moving image or a still image. The input signal peak detection unit 402 detects the peak value of the input video signal. The organic EL display unit 407 is connected to the source driver 404 by a plurality of source lines, connected to the write gate driver 405 by a plurality of write gate lines, and connected to the lighting gate driver 406 by a plurality of lighting gate lines. Further, in the organic EL display unit 407, organic EL pixel cells are arranged in a matrix corresponding to a portion where the source line, the writing gate line, and the lighting gate line intersect. The drive control unit 403 controls the drive of the write gate driver 405 and drives the output gain of the source driver 404 and the lighting gate driver 406 according to the detection results of the input signal motion detection unit 401 and the input signal peak detection unit 402. Control timing. The source driver 404 changes pixel data output to the source line in accordance with a control signal from the drive control unit 403. The write gate driver 405 outputs a write scan signal to the pixel to the write gate line. The lighting gate driver 406 outputs a lighting scanning signal to the lighting gate line. The pixel cell includes a plurality of switching elements (TFTs), holds pixel data of the source line in the pixel cell by a write scanning signal, and emits light with a luminance corresponding to the pixel data by a lighting operation signal.

  Hereinafter, the operation in Embodiment 4 of the present invention will be described with reference to FIG. In FIG. 10, (e) shows a control state when peak luminance detection is not performed. By detecting the moving image, the light emission period and the light emission gain within a predetermined period (for example, one frame) are changed to improve the moving image visibility. However, since there is no peak luminance information, the maximum luminance light emission set as the display unit is controlled so as to be always possible. Therefore, the range for shortening the light emission period is reduced. The dotted line indicates the maximum value of the light emission gain. (F) shows the control state when the peak luminance is detected. It is the same that the moving image visibility is improved by changing the light emission period and the light emission gain within the predetermined period by detecting the moving image. However, the peak luminance information is controlled along a solid line that enables necessary luminance emission. Therefore, the light emission period can be made shorter than (e). As described above, according to the present embodiment, by detecting the peak luminance, when the peak luminance is low, it is possible to make it closer to the impulse-type driving, and the moving image visibility can be improved. Further, in the case of a still image, the life of the EL element can be reduced by bringing it closer to hold-type driving. Although the moving image detection determination is made based on a predetermined amount of movement, the light emission period and the light emission luminance may be changed according to the amount of movement.

  The organic EL display device driving method and the organic EL display device according to the present invention make it possible to improve the visibility of the moving image and suppress the deterioration of the lifetime when the input video signal is displayed on the display unit constituted by the organic EL element. It has a special effect of realizing a display device, and is useful as a display device for the purpose of improving display quality.

1 is a block diagram showing a configuration of an organic EL display device according to Embodiment 1 of the present invention. Drive timing chart in Embodiment 1 of the present invention The block diagram which shows the structure of the organic electroluminescence display in Embodiment 2 of this invention. Drive timing chart in Embodiment 2 of the present invention Block diagram showing an example of the internal configuration of the source driver The block diagram which shows the structure of the organic electroluminescence display in Embodiment 3 of this invention. Surface emission drive timing chart in Embodiment 3 of the present invention Sequential light emission drive timing chart in Embodiment 3 of the present invention The block diagram which shows the structure of the organic electroluminescence display in Embodiment 4 of this invention. Flowchart of operation in Embodiment 4 of the present invention Block diagram showing the configuration of a conventional liquid crystal display device Drive timing chart of conventional liquid crystal display device Operation explanatory diagram of impulse drive The figure which shows the relationship between the light emission of an organic EL element, and a luminance degradation

Explanation of symbols

101 Signal gain converter 102, 201, 302, 401, 702 Input signal motion detector 103, 202, 303, 403, 703 Drive controller 104, 203, 304, 404, 704 Source driver 105, 204, 305, 405 Write Gate driver 106, 205, 306, 406 Lighting gate driver 107, 206, 307, 407 Organic EL display unit 301 Frequency conversion unit 402 Input signal peak detection unit 701 Line double speed conversion unit 705 Gate driver 706 Opposing drive unit 707 Liquid crystal display unit 708 Backlight control unit 709 Backlight

Claims (8)

An input signal motion detector that detects whether the input video signal is a moving image or a still image, a signal gain converter that changes the gain of the video signal, and a plurality of source lines to which pixel data is supplied A plurality of write gate lines to which a write scan signal is supplied to the pixel, a plurality of light gate lines to which a pixel scan signal is supplied, and the source line, the write gate line, and the lighting gate line. An organic EL display unit in which organic EL pixel cells are arranged in a matrix corresponding to the portion to be formed, a source driver that drives the source line, a write gate driver that drives the write gate line, and the lighting gate line Driving gate driver for driving, drive control unit for controlling the source driver, the writing gate driver, and the lighting gate driver When the input video signal is a moving image, the gain of the signal gain converter is increased so that the light emission period within a predetermined period of the organic EL display device is shortened. An organic EL display device which controls a lighting scanning signal driving period from the lighting gate driver. An input signal motion detector that detects whether an input video signal is a moving image or a still image, a plurality of source lines to which pixel data is supplied, and a plurality of signals to which writing scanning signals for pixels are supplied An organic EL pixel cell is arranged in a matrix corresponding to a writing gate line, a plurality of lighting gate lines to which a pixel lighting scanning signal is supplied, and a portion where the source line, the writing gate line, and the lighting gate line intersect. The organic EL display unit arranged, a source driver for driving the source line, a write gate driver for driving the write gate line, a lighting gate driver for driving the lighting gate line, the source driver and the write gate An organic EL display device having a driver and a drive control unit for controlling the lighting gate driver, Is a moving image, the output signal gain of the source driver is increased, and the lighting scanning signal driving period from the lighting gate driver is controlled so that the light emission period within the predetermined period of the organic EL display device is shortened. An organic EL display device. 3. The organic EL display device according to claim 2, wherein the source driver includes a D / A converter and changes the level of the output signal to the source line by a control signal. When the input video signal is a moving image, the gain of the signal output to the source line and the light emission period within a predetermined period of the organic EL display device are controlled according to the magnitude of the movement. The organic EL display device according to any one of claims 1 to 3. 5. The organic EL display device according to claim 1, wherein when changing the signal gain and the light emission period, control is performed so that the average luminance of the display screen does not change. 2. The driving of the lighting gate line is controlled so that the line is sequentially lit for a predetermined period after writing in synchronization with data writing to pixels in a line unit by the writing gate line. The organic EL display device according to claim 5. A frequency converter that changes the frame frequency of the input video signal is provided so that all lines are turned on simultaneously for a predetermined period after writing in synchronization with the completion of data writing to pixels of all lines by the writing gate line. 6. The organic EL display device according to claim 1, wherein driving of the lighting gate line is controlled. An input signal peak detection unit that detects a peak value of the input video signal is provided, and when the input video signal is a moving image, the gain of the signal to the source line and the 8. The organic EL display device according to claim 1, wherein a light emission period within a predetermined period in the organic EL display unit is controlled.

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