JP2011085768A - Organic el display device and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display device capable of suppressing a reduction in service life of an organic EL element, and capable of improving moving-image resolution without causing a reduction in brightness of an image. <P>SOLUTION: The organic EL display device includes: a display part including a plurality of pixel parts; a data line driving circuit to supply to the display part, a data signal corresponding to the light emission amount of the organic EL element of each of the pixel parts; a scanning line driving circuit to perform control to write the data signal to each of the pixel parts; and a control part to control the data line driving circuit and the scanning line driving circuit so that the organic EL elements of the pixel parts may emit light, in a display period including a light emission period allowing the organic EL elements to emit the light and a black insertion period not allowing the organic EL elements to emit the light, as one unit. The control part is configured to, in the case the luminance corresponding to the data signal to be written in the pixel part exceeds a predetermined value, in the light emission period, control the organic EL element of the pixel part to emit the light based on a data signal corresponding to the luminance shown by a difference between the luminance exceeding the predetermined value of the pixel part and the predetermined luminance value, and in the black insertion period, control the organic EL element of the pixel part to emit the light based on a data signal corresponding to the luminance shown by the predetermined value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic EL display device and a control method thereof.

  An organic electroluminescence element (hereinafter referred to as an organic EL element) has a structure in which an organic layer including a light emitting layer is sandwiched between an anode and a cathode, and holes are injected from the anode and electrons are injected from the cathode. It is a light-emitting element that takes out light emission by recombining them.

  Display devices using such organic EL elements (hereinafter referred to as organic EL display devices) are attracting attention as candidates for flat panel displays (FPDs) that are applied to, for example, televisions, and research and development aimed at widespread use. It is actively done.

  Unlike an impulse-type display method such as a CRT (cathode ray tube), the organic EL display device is a hold-type display that maintains the brightness of the previous image until the next rewrite signal is input to the pixel, similar to a liquid crystal display. Display method (hereinafter referred to as hold drive). That is, the organic EL display device continues to display the same image for one frame period (for example, 1/60 s).

  Moreover, the response speed of the organic EL device used for the organic EL display device is faster than a liquid crystal material generally used for the liquid crystal display device. In addition, since a backlight is not required unlike a liquid crystal display device, it is possible to further reduce the thickness and weight and to reduce power consumption compared to a liquid crystal display device.

  However, although the responsiveness of the organic EL device is higher than that of the liquid crystal, the hold drive is performed as in the liquid crystal display device. This is because when looking at an object in which a human is moving, the direction of movement is predicted and the movement of the line of sight is followed, but in the hold drive, the same image is displayed in one frame period (for example, 1/60 s). Therefore, a shift occurs between the predicted position and the actually displayed position, and the shifted video is synthesized in the human brain. That is, in hold driving, hold blur that causes the video to be blurred due to the relationship between the video display method and human visual characteristics occurs.

  Therefore, in order to suppress the hold blur and increase the moving image resolution, it is necessary to perform black insertion driving or the like as in the liquid crystal display device (for example, Patent Documents 1 to 3). Here, the black insertion drive is a display method in which a black display period is provided in a display period of one field period in which the same video (image) is displayed, thereby shortening the video display time. The moving image resolution (moving image display performance) can be increased by this black insertion drive or the like.

JP 2004-264481 A JP 2006-330138 A JP 2002-23707 A

  However, in Patent Documents 1 to 3, although the moving image resolution (moving image display performance) is increased by black insertion driving or the like, consideration is given to a decrease in image brightness due to black insertion driving or deterioration of organic EL elements. not enough.

  FIG. 1 is a diagram for explaining a conventional black insertion driving method. FIG. 2 is a diagram illustrating a current value applied to one pixel of a conventional organic EL display device.

  In FIG. 1, the vertical axis indicates the position of a screen on which a conventional organic EL display device displays an image, and the horizontal axis indicates time. In FIG. 1, a black insertion period is provided during one field period (for example, 30 Hz). That is, on the screen on which the organic EL display device displays an image, the image is displayed during one frame period (16.7 ms) (hereinafter referred to as a light emission period) (described as a light emission period portion in the figure), and a black insertion period. In the next one frame period (16.7 ms), black is displayed (described as a black insertion period portion in the figure), thereby performing black insertion driving in one field period (33.2 ms).

  In FIG. 2, the current value applied to one pixel when the black insertion drive is not performed (normal drive) ((1) in the drawing) and the same average luminance as that during the normal drive when black insertion drive is realized. 1 shows a current value ((2) in the figure) applied to one pixel. Here, the light emission duty ratio of the black insertion drive is set to 50%.

  In that case, in order to achieve the same average luminance at the time of black insertion driving at the time of normal driving (duty ratio 100%), for example, at the time of black insertion driving, the driving current and the luminance are almost proportional, so it is twice that at the time of normal driving. It is necessary to apply a current value of. However, when the organic EL element is loaded with a current value twice as large as that during normal driving, deterioration of the organic EL element is promoted. Further, in order to increase the maximum current that flows through the organic EL element, the size of a TFT (Thin Film Transistor) that drives the organic EL element increases. As a result, power consumption increases.

  As described above, when the black insertion drive is performed, the moving image resolution (moving image display performance) is increased, but the brightness of the video is reduced by the black insertion drive. In order to prevent the brightness of the video from being lowered due to the black insertion drive, the luminance within the video display time must be increased. However, this promotes deterioration of the organic EL element and shortens the life. This is because the lifetime of the organic EL element tends to be shorter as the emission luminance is higher. Therefore, the lifetime of the organic EL element is shortened as the light emission duty ratio is lowered to perform black insertion driving.

  The present invention has been made in view of the above-described circumstances, and provides an organic EL display device capable of improving the moving image resolution without reducing the lifetime of the organic EL element and reducing the brightness of the image, and a control method thereof. For the purpose.

  In order to achieve the above object, an organic EL display device according to the present invention includes a display unit having a plurality of pixel units each including an organic EL element, and a data signal corresponding to a light emission amount of the organic EL element of each pixel unit. A data line driving circuit to be supplied to the display unit, a scanning line driving circuit for controlling writing of the data signal to each pixel unit, a light emission period for causing the organic EL element to emit light, and a data signal corresponding to a black signal The organic EL element of the pixel portion is controlled by controlling the data line driving circuit and the scanning line driving circuit in a display period in which a black insertion period in which the organic EL element is not supplied to emit light is supplied as a unit. A control unit that emits light, and when the luminance corresponding to a data signal written to the pixel unit in the light emission period exceeds a predetermined value, Based on the data signal corresponding to the luminance indicated by the difference between the luminance of the pixel portion exceeding the predetermined value and the predetermined value, the organic EL element of the pixel portion exceeding the predetermined value is caused to emit light, and in the black insertion period, Based on the data signal corresponding to the luminance indicated by the predetermined value, the organic EL element of the pixel portion exceeding the predetermined value is caused to emit light.

  ADVANTAGE OF THE INVENTION According to this invention, the organic EL display apparatus which can improve the moving image resolution, without suppressing the lifetime reduction of an organic EL element and reducing the brightness of an image | video, and its control method are realizable.

It is a figure for demonstrating the conventional black insertion drive method. It is a figure which shows the electric current value applied to 1 pixel of the conventional organic EL display apparatus. 1 is a functional block diagram of an organic EL display device in an embodiment of the present invention. It is a figure for demonstrating the black insertion drive method of the organic electroluminescence display which concerns on embodiment of this invention. It is a figure which shows the one aspect | mode of the electric current value applied to 1 pixel of the organic electroluminescence display which concerns on embodiment of this invention. It is a figure which shows the one aspect | mode of the electric current value applied to 1 pixel of the organic electroluminescence display which concerns on embodiment of this invention. It is a figure which shows the one aspect | mode of the electric current value applied to 1 pixel of the organic electroluminescence display which concerns on embodiment of this invention. It is a figure for demonstrating the black insertion drive in this Embodiment using the allocation table of the output luminance with respect to the input luminance memorize | stored in the memory | storage part. It is a figure for demonstrating the black insertion drive in this Embodiment using the allocation table of the output luminance with respect to the input luminance memorize | stored in the memory | storage part. It is a flowchart for demonstrating the method of the black insertion drive of the organic electroluminescence display which concerns on embodiment of this invention. It is a figure which shows an example of the display apparatus using the organic electroluminescent display apparatus of this invention.

  An organic EL display device according to one embodiment of the present invention supplies a display unit having a plurality of pixel units including organic EL elements and a data signal corresponding to the light emission amount of the organic EL element of each pixel unit to the display unit. A data line driving circuit; a scanning line driving circuit for controlling writing of the data signal to each pixel portion; and a data signal corresponding to a light emission period and a black signal for emitting light from the organic EL element. And a control unit that controls the data line driving circuit and the scanning line driving circuit to emit light from the organic EL element of the pixel unit in a display period in which a black insertion period in which the organic EL element does not emit light is one unit. And when the luminance corresponding to the data signal written to the pixel unit in the light emission period exceeds a predetermined value, the control unit exceeds the predetermined value in the light emission period. Based on a data signal corresponding to the luminance indicated by the difference between the luminance of the pixel portion and the predetermined value, the organic EL element of the pixel portion exceeding the predetermined value emits light, and the luminance indicated by the predetermined value during the black insertion period The organic EL element of the pixel portion exceeding the predetermined value is caused to emit light based on the data signal corresponding to.

  According to this aspect, in each pixel unit (each pixel) included in the display unit, when the luminance corresponding to the data signal to be written exceeds a predetermined value, the organic EL of the corresponding pixel unit whose luminance exceeds the predetermined value during the light emission period. Black insertion driving for increasing the amount of current supplied to the element is not performed. In the organic EL element included in the corresponding pixel portion, the amount of current supplied to the organic EL element is suppressed to a predetermined value or less during the light emission period, but the current is insufficient for the organic EL element during the black insertion period for black display. Supply quantity.

  Thus, in the pixel portion where the luminance exceeds a predetermined value, the luminance is set to a predetermined value by emitting light from the organic EL element that combines the current amount supplied during the light emission period and the current amount supplied during the black insertion period. It is possible to ensure the average luminance of the pixel portion exceeding. Therefore, not only can the black insertion drive be performed while maintaining the average luminance of the pixel portion, but also it is possible to prevent the organic EL element from being deteriorated due to a transient current load.

  In the organic EL display device, the organic EL element writes a data signal corresponding to a black signal, that is, performs black insertion driving in order to reset the afterimage after the light emission period. As described above, there is a case where the organic EL element emits light even during the black insertion period. However, the chance of causing the organic EL element to emit light during the black insertion period can be reduced by setting a predetermined value. Therefore, it is possible to suppress a reduction in the resolution of moving image display due to an afterimage.

  Here, the organic EL display device further includes a storage unit storing predetermined data corresponding to a gamma correction curve indicating luminance-gradation characteristics, and the control unit is configured to perform the black insertion period. The organic EL element of the pixel unit exceeding the predetermined value without performing luminance-gradation correction based on the predetermined data stored in the storage unit with respect to the data signal corresponding to the luminance indicated by the predetermined value In the light emission period, luminance-gradation correction is performed on the data signal corresponding to the luminance indicated by the difference based on predetermined data stored in the storage unit, and the pixel unit organic The EL element may emit light.

  According to this aspect, when the organic EL element of the pixel unit exceeding the predetermined value is caused to emit light during the black insertion period, the data signal corresponds to the data signal written to the pixel unit over both the light emission period and the black insertion period. Regardless of the overall brightness level, it becomes fixed data. That is, since the average luminance does not change, the luminance-gradation correction process is simplified as a whole.

  In addition, when the organic EL element of the pixel portion emits light during the light emission period, the light emission period corresponds to whether or not the luminance corresponding to the data signal for causing the organic EL element to emit light exceeds a predetermined value. The luminance-gradation correction is performed on the data signal to be processed. By doing in this way, in the light emission period, when the luminance corresponding to the data signal that causes the organic EL element to emit light exceeds a predetermined value, the luminance corresponding to the data signal that causes the organic EL element to emit light does not exceed the predetermined value. In this case, the processing can be made common. Therefore, the luminance-gradation correction process is simplified as a whole.

  The predetermined value may be a value corresponding to a luminance of 50 percent when the luminance corresponding to the data signal indicating all white is 100 percent.

  According to this aspect, when the organic EL element emits light during the black insertion period, the luminance corresponding to the data signal to be written to the pixel unit during the light emission period exceeds 50%. Therefore, the frequency with which the organic EL element emits light during the black insertion period can be reduced, and a reduction in the resolution of moving image display due to an afterimage can be suppressed.

  In addition, the amount of light emitted from the organic EL element in the black insertion period is fixed to a value corresponding to 50% when the luminance corresponding to the all-white data signal is 100%. As a result, the voltage can be set in accordance with the current value of 50%, so that the power consumption can be reduced as compared with the conventional black insertion driving.

  The organic EL display device according to one embodiment of the present invention includes a display portion including a plurality of pixel portions each including an organic EL element, and a data signal corresponding to the light emission amount of the organic EL element in each pixel portion. A data line driving circuit to be supplied; a scanning line driving circuit for controlling writing of the data signal to each pixel portion; a light emission period for causing the organic EL element to emit light; and a data signal corresponding to a black signal to the organic EL element The organic EL element in the pixel portion is caused to emit light by controlling the data line driving circuit and the scanning line driving circuit in a display period in which a black insertion period in which the organic EL element is not emitted is set as one unit. A control unit, and when the luminance corresponding to the data signal written to the pixel unit in the light emission period exceeds a predetermined value, the control unit has the predetermined value in the light emission period. Based on the data signal corresponding to the luminance indicated, the organic EL element of the pixel portion exceeding the predetermined value emits light, and during the black insertion period, the difference between the luminance of the pixel portion exceeding the predetermined value and the predetermined value is Based on the data signal corresponding to the indicated luminance, the organic EL element of the pixel portion exceeding the predetermined value is caused to emit light.

  According to this aspect, in each pixel unit included in the display unit, when the luminance corresponding to the data signal to be written exceeds a predetermined value, the luminance is supplied to the organic EL element of the corresponding pixel unit whose luminance exceeds the predetermined value within the light emission period. Black insertion drive that increases the amount of current is not performed. In the organic EL element included in the corresponding pixel portion, the amount of current supplied to the organic EL element is suppressed to a predetermined value or less during the light emission period, but the current is insufficient for the organic EL element during the black insertion period for black display. Supply quantity.

  Thus, in the pixel portion where the luminance exceeds a predetermined value, the luminance is set to a predetermined value by emitting light from the organic EL element that combines the current amount supplied during the light emission period and the current amount supplied during the black insertion period. It is possible to ensure the average luminance of the pixel portion exceeding. Therefore, not only can the black insertion drive be performed while maintaining the average luminance of the pixel portion, but also it is possible to prevent the organic EL element from being deteriorated due to a transient current load.

  In the organic EL display device, the organic EL element writes a data signal corresponding to a black signal, that is, performs black insertion driving in order to reset the afterimage after the light emission period. As described above, there is a case where the organic EL element emits light even during the black insertion period. However, the chance of causing the organic EL element to emit light during the black insertion period can be reduced by setting a predetermined value. Therefore, it is possible to suppress a reduction in the resolution of moving image display due to an afterimage.

  In addition, the organic EL display device further includes a storage unit that stores predetermined data corresponding to a gamma correction curve indicating a luminance-gradation characteristic, and the control unit includes the storage unit during the light emission period. The organic EL element in the pixel portion exceeding the predetermined value is emitted without performing luminance-gradation correction based on the predetermined data stored in the storage unit with respect to the data signal corresponding to the luminance indicated by the predetermined value In the black insertion period, luminance-gradation correction based on predetermined data stored in the storage unit is performed on the data signal corresponding to the luminance indicated by the difference, and the organic EL of the pixel unit The element may emit light.

  According to this aspect, when the organic EL element of the pixel unit exceeding the predetermined value is caused to emit light during the black insertion period, the data signal corresponds to the data signal written to the pixel unit over both the light emission period and the black insertion period. Regardless of the overall brightness level, it becomes fixed data. That is, since the average luminance does not change, the luminance-gradation correction process is simplified as a whole.

  The predetermined value may be a value corresponding to a luminance of 50 percent when the luminance corresponding to the data signal indicating all white is 100 percent.

  According to this aspect, when the organic EL element emits light during the black insertion period, the luminance corresponding to the data signal to be written to the pixel unit during the light emission period exceeds 50%. Therefore, the frequency with which the organic EL element emits light during the black insertion period can be reduced, and a reduction in the resolution of moving image display due to an afterimage can be suppressed.

  In addition, the amount of light emitted from the organic EL element in the light emission period is fixed to a value corresponding to 50% when the luminance corresponding to the all-white data signal is 100%. As a result, the voltage can be set in accordance with the current value of 50%, so that the power consumption can be reduced as compared with the conventional black insertion driving.

  Further, the amount of light emitted from the organic element during the light emission period is set to 50 percent, and the amount of light emitted from the organic EL element during the black insertion period is set as the remaining percentage, so that a large amount of light is emitted first. Thereby, the impression given to eyes becomes more natural.

  In addition, a method for controlling an organic EL display device according to an aspect of the present invention includes: a display unit including a plurality of pixel units including organic EL elements; and a data signal corresponding to the light emission amount of the organic EL element in each pixel unit. A data line driving circuit to be supplied to the display unit, a scanning line driving circuit for controlling writing of the data signal to each pixel unit, a light emission period for causing the organic EL element to emit light, and a data signal corresponding to a black signal By controlling the data line driving circuit and the scanning line driving circuit in a display period in which a black insertion period in which the organic EL element is not supplied to emit light is supplied as a unit of the display period, the data line driving circuit and the scanning line driving circuit are controlled. A control unit for causing the organic EL element to emit light, the control method corresponding to a data signal written to the pixel unit in the light emission period. In the determination step for determining whether or not the luminance exceeds a predetermined value, and in the determination step, the control unit determines that the luminance corresponding to the data signal to be written to the pixel unit in the light emission period exceeds a predetermined value. In the light emission period, light is emitted from the organic EL element of the pixel portion exceeding the predetermined value based on a data signal corresponding to the luminance indicated by the difference between the luminance of the pixel portion exceeding the predetermined value and the predetermined value. And a control step of causing the organic EL elements in the pixel portion exceeding the predetermined value to emit light based on a data signal corresponding to the luminance indicated by the predetermined value in the black insertion period.

  In addition, a method for controlling an organic EL display device according to another aspect of the present invention includes a display unit having a plurality of pixel units each including an organic EL element, and a data signal corresponding to the light emission amount of the organic EL element in each pixel unit. A data line driving circuit for supplying the display unit with data, a scanning line driving circuit for controlling writing of the data signal to each pixel unit, a light emission period for causing the organic EL element to emit light, and a data signal corresponding to the black signal The pixel unit is controlled by controlling the data line driving circuit and the scanning line driving circuit in a display period in which a black insertion period in which the organic EL element should not be caused to emit light is supplied to the organic EL element. A control unit that emits light from the organic EL element, and corresponds to a data signal written to the pixel unit in the light emission period in the control unit. In the determination step for determining whether or not the degree exceeds a predetermined value, and in the determination step, the control unit determines that the luminance corresponding to the data signal to be written to the pixel unit in the light emission period exceeds a predetermined value. In the light emission period, the organic EL element of the pixel portion exceeding the predetermined value is caused to emit light based on a data signal corresponding to the luminance indicated by the predetermined value, and the predetermined value is exceeded in the black insertion period. Based on the data signal corresponding to the luminance indicated by the difference between the luminance of the pixel portion and the predetermined value, the organic EL element of the pixel portion exceeding the predetermined value is caused to emit light.

  Note that the present invention can be realized not only as a method using a device or processing means constituting the device as a step, but also as an integrated circuit including processing means provided in such a device.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 3 is a functional block diagram of the organic EL display device according to the embodiment of the present invention. The organic EL display device 100 illustrated in FIG. 3 includes a control unit 10, a data line driving circuit 11, a scanning line driving circuit 12, and a display unit 13. The organic EL display device 100 is driven to insert black by the control unit 10 and displays an image based on the input video signal. Hereinafter, the black insertion drive (hereinafter, referred to as the “black insertion drive”) in the present embodiment will be mainly described, and the other parts are the same as those in the prior art, and the description thereof will be omitted.

  The display unit 13 includes a plurality of pixel units (pixels), and displays an image based on a video signal input to the organic EL display device 100 from the outside. Specifically, the display unit 13 displays an image when the organic EL element included in the pixel emits light by supplying current from the data line driving circuit 11 and the scanning line driving circuit 12.

  The data line driving circuit 11 supplies the display unit 13 with a data signal corresponding to the amount of light emitted by the organic EL element of each pixel included in the display unit 13 according to the video signal input by the control unit 10.

  The scanning line driving circuit 12 controls writing of data signals supplied from the data line driving circuit 11 to each pixel included in the display unit 13.

  The control unit 10 includes a control circuit 20, an image quality conversion circuit 101, and a video signal output circuit 106, and has a function of controlling the data line driving circuit 11 and the scanning line driving circuit 12. The control unit 10 controls the data line driving circuit 11 and the scanning line driving circuit 12 to cause each pixel unit included in the display unit 13 to emit light and cause the display unit 13 to display an image.

  In addition, the control unit 10 drives the data line driving circuit 11 and the scanning line during the display period in which the light emission period (for example, one frame period) and the black insertion period (for example, one frame period) are one unit (for example, one field period). The black insertion driving is performed by controlling the circuit 12 to cause each pixel of the display unit 13 to emit light. Here, the light emission period is a period in which the organic EL element of the pixel included in the display unit 13 emits light, and the black insertion period is a period in which the organic EL element of the pixel included in the display unit 13 does not emit light (black display). It should be a period.

  Hereinafter, it demonstrates in detail using the component which comprises the control part 10. FIG.

  In order to display an image on the display unit 13, the image quality conversion circuit 101 converts the image quality of the video signal input to the organic EL display device 100 and outputs the converted video signal to the luminance signal determination unit 102. Note that the image quality conversion includes those performed for displaying an image on the display unit 13, for example, converting a video signal into a video signal including a luminance signal and a color difference signal, such as a resolution change.

  The control circuit 20 includes a luminance signal determination unit 102, a storage unit 103, a light emission frame signal creation unit 104, and a black insertion frame signal creation unit 105. Note that the storage unit 103 only needs to be provided either inside or outside the control unit 10, and here, the storage unit 103 is provided outside the control unit 10 as shown in FIG. 3.

  The luminance signal determination unit 102 determines whether the luminance of each pixel of the display unit 13 exceeds a predetermined value from the video signal input by the image quality conversion circuit 101.

  Here, for example, the predetermined value is a value corresponding to half of white display (luminance 100%) when the organic EL display device 100 performs conventional black insertion driving with a duty ratio of 50%, that is, luminance 50%. Note that when the predetermined value is a value corresponding to a luminance of 50%, it is preferable because the frequency of causing the organic EL element to emit light during the black insertion period can be reduced and a reduction in the resolution of moving image display due to an afterimage can be suppressed. Not limited to this, the luminance may be 60% or 40%.

  The predetermined value is stored in the storage unit 103, and the luminance signal determination unit 102 acquires the predetermined value from the storage unit 103 in advance. Note that the predetermined value may be set in advance in the luminance signal determination unit 102 without being stored in the storage unit 103.

  When the luminance signal determination unit 102 determines that the luminance of a certain pixel exceeds a predetermined value, the luminance signal determination unit 102 performs the main black insertion driving for performing, for example, white display (display for 50% luminance) in the black insertion period in the corresponding pixel. Is output to the light emission frame signal creation unit 104 and the black insertion frame signal creation unit 105. In addition, the luminance signal determination unit 102 outputs the video signal input by the image quality conversion circuit 101 to the light emission frame signal generation unit 104 and the black insertion frame signal generation unit 105.

  On the other hand, if the luminance signal determination unit 102 determines that the luminance of the pixel does not exceed the predetermined value, the luminance frame signal is a signal indicating that the conventional black insertion drive for performing black display, for example, in the black insertion period is performed in the corresponding pixel. The data is output to the creation unit 104 and the black insertion frame signal creation unit 105. In addition, the luminance signal determination unit 102 outputs the video signal input by the image quality conversion circuit 101 to the light emission frame signal generation unit 104 and the black insertion frame signal generation unit 105.

  The storage unit 103 is, for example, a memory. A predetermined value is stored in the storage unit 103. For example, it corresponds to half of white display (luminance 100%) when the organic EL display device 100 performs conventional black insertion driving with a duty ratio of 50%, that is, luminance 50%. A predetermined value that is a value to be stored is stored. Further, the storage unit 103 stores, for example, an LUT (Look up Table) that is an output luminance allocation table for input luminance. For example, an LUT in which predetermined data corresponding to a gamma correction curve indicating luminance-gradation characteristics is stored.

  The light emission frame signal creation unit 104 creates a signal indicating a light emission frame in the light emission period from the input video signal according to the determination result of the luminance signal determination unit 102.

  Specifically, it is assumed that a signal indicating that the black insertion driving is performed for a certain pixel in the frame and a signal indicating that the conventional black insertion driving is performed for other pixels are received. Then, the light emission frame signal generation unit 104 uses a luminance signal corresponding to the difference luminance obtained by subtracting a predetermined value from the luminance indicated by the corresponding pixel in the corresponding pixel in the frame, and in other than the corresponding pixel in the frame. Generates a signal indicating a light emission frame in the light emission period, using a luminance signal corresponding to the luminance indicated by other than the corresponding pixel. Here, the light emission frame signal creation unit 104 performs, for example, luminance-gradation correction on the difference luminance based on the LUT stored in the storage unit 103, thereby obtaining a luminance signal corresponding to the difference luminance. create.

  In addition, the light emission frame signal generation unit 104 outputs a signal indicating the generated light emission frame to the video signal output circuit 106.

  The black insertion frame signal creation unit 105 creates a signal indicating a black insertion frame in the black insertion period from the input video signal according to the determination result of the luminance signal determination unit 102.

  Specifically, it is assumed that a signal indicating that the black insertion driving is performed for a certain pixel in the frame and a signal indicating that the conventional black insertion driving is performed for other pixels are received. Then, the black insertion frame signal creation unit 105 uses a luminance signal corresponding to a predetermined value at a corresponding pixel in the frame, and performs a black insertion period so that black display is performed at other than the corresponding pixel in the frame. A signal indicating the black insertion frame at is generated.

  Further, the black insertion frame signal creation unit 105 outputs a signal indicating the created black insertion frame to the video signal output circuit 106.

  The video signal output circuit 106 receives a video signal of a display period input by the control circuit 20 as a unit of a light emission period and a black insertion period, for example, a video signal of a 120 Hz light emission frame and a 120 Hz black insertion frame as a data line. Output to the drive circuit 11. Specifically, the signal indicating the 120 Hz emission frame input by the emission frame signal creation unit 104 and the signal indicating the 120 Hz black insertion frame input by the black insertion frame signal creation unit 105 are input to the data line driving circuit 11. Output.

  As described above, when the luminance corresponding to the data signal to be written in the pixel unit included in the display unit 13 during the light emission period exceeds the predetermined value from the video signal input to the organic EL display device 100, the control circuit 20 has the luminance. In the pixel exceeding the predetermined value, the organic EL element is caused to emit light based on the data signal corresponding to the luminance indicated by the difference between the luminance and the predetermined value during the light emission period, and the data corresponding to the luminance indicated by the predetermined value during the black insertion period. Based on the signal, the organic EL element is caused to emit light.

  Further, when the organic EL element emits light during the black insertion period in the corresponding pixel, the control circuit 20 performs luminance-gradation based on the LUT stored in the storage unit 103 for the data signal causing the organic EL element to emit light. The organic EL element of the corresponding pixel exceeding a predetermined value is caused to emit light without performing correction. On the other hand, when the organic EL element emits light during the light emission period in the corresponding pixel, the control circuit 20 performs luminance-gradation correction based on the LUT stored in the storage unit 103 for the data signal that causes the organic EL element to emit light. The organic EL element of the pixel is caused to emit light.

  In this way, even in the actual black insertion drive, the data signal can be fixed data regardless of the overall luminance level corresponding to the data signal written to the pixel over both the light emission period and the black insertion period. it can. Further, the processing for the data signal for causing the organic EL element to emit light during the light emission period can be made common in the case of the main black insertion driving and the case of the conventional black insertion driving. Thereby, the luminance-gradation correction process is managed as a whole.

  As described above, the organic EL display device 100 is configured.

  FIG. 4 is a diagram for explaining a black insertion driving method of the organic EL display device according to the embodiment of the present invention. 5 to 7 are diagrams showing examples of current values applied to a predetermined pixel during black insertion driving of the organic EL display device according to the embodiment of the present invention.

  In FIG. 4, the vertical axis indicates the position of the screen on which the organic EL display device 100 displays an image, and the horizontal axis indicates time. In FIG. 4, a black insertion period is provided in a period of one field period (for example, 30 Hz). That is, on the screen on which the organic EL display device 100 displays an image, the image is displayed in one frame period (16.7 ms) that is a light emission period (described as a light emission period portion in the drawing), and the next is a black insertion period. During one frame period (16.7 ms), black is displayed (denoted as a black insertion period portion in the figure), so that black insertion driving is performed during one field period (33.2 ms). However, the organic EL display device 100, for example, when there is a luminance exceeding a predetermined value (luminance 50%) within one frame, for the luminance exceeding the predetermined value in the corresponding pixel, The light emission is performed in the light emission period portion, and the luminance of a predetermined value is emitted in the black insertion period (black insertion period portion in the figure).

  In this way, during black insertion driving, in order to compensate for the average luminance, a current is supplied to the pixel exceeding a predetermined value (in this case, a value corresponding to 50% luminance) that promotes deterioration of the organic EL element in the light emitting period portion. Can be suppressed from being applied. Thereby, it is possible to prevent the organic EL element from deteriorating. In addition, by doing in this way, it is possible to ensure an average luminance equivalent to that in the case where black insertion driving is not performed.

  In the above, for convenience of explanation, an example of 30 Hz is given as an example of one field cycle. Needless to say, it may be 60 Hz. In that case, as shown in FIG. 3, one field period is 60 Hz, and one frame period is 120 Hz.

  FIG. 5 shows a current value ((3) in the figure) applied to one predetermined pixel by the data line driving circuit 11 during the main black insertion driving in the organic EL display device 100. For comparison, the current value ((1) in the figure) applied to a predetermined pixel during normal driving (duty ratio 100%) and the predetermined one pixel during black insertion driving with a conventional light emission duty ratio of 50% The current value ((2) in the figure) applied to is shown. Here, in the figure, a period a to a period d each indicate one frame period, each of the periods a and c indicates a light emission period, and each of the periods b and d indicates a black insertion period. The period a and the period b indicate one field period (display period). Further, the white display when the organic EL display device 100 performs conventional black insertion driving with a duty ratio of 50% is set to 100% luminance.

  In the normal driving shown in (1), a current value corresponding to white display is applied in one field period of period a and period b, and 15% of luminance is supported in one field period of period c and period d. Suppose that a current value is applied.

  In that case, in the conventional black insertion driving shown in (2), a current value of 0 corresponding to black display is applied in each of the periods b and d. Here, in order to realize the same average luminance as that in the normal driving, a current value twice that in the normal driving is applied in the period a. As described above, a transient current load is applied to the organic EL element, which leads to deterioration of the organic EL element. Note that in the period c, a current value corresponding to 30% of the luminance that is twice that in normal driving is applied.

  On the other hand, in the main black insertion driving shown in (3), a current value twice that in the normal driving corresponding to the white display is not applied in the period a, and the luminance corresponding to the white display of the conventional black insertion driving is predetermined. A current value corresponding to the luminance of the difference obtained by subtracting the value is applied. In a period b, a current value corresponding to a predetermined luminance is applied. In FIG. 5, the predetermined value is a value corresponding to 50% luminance, that is, a value corresponding to white display during normal driving. Further, since one field period of the period c and the period d is the same as the conventional black insertion driving shown in (2), description thereof is omitted.

  The reason for driving in this manner is to prevent a current value corresponding to a luminance exceeding a predetermined value (luminance 50%) from being applied to the organic EL element. Thereby, deterioration of the organic EL element can be prevented from being promoted. In order to achieve the same average luminance as that during normal driving, a current value corresponding to the luminance not to be displayed in the light emission period is applied during the black insertion period where black is originally displayed. Here, a current value corresponding to the luminance corresponding to the difference from the predetermined value is applied during the light emission period, and a current value corresponding to the predetermined value is applied during the black insertion period.

  FIG. 6 shows an example in which a current value corresponding to a luminance of 35% is applied instead of white display during normal driving in one field period of period a and period b. Note that one field period of the period c and the period d is the same as that in FIG.

  In this case, in the conventional black insertion driving shown in (2), a current value of 0 is applied as black display in the period b, so that the same average luminance as that in the normal driving is realized in the period a. A current value that is twice that in normal driving, that is, a current value corresponding to a luminance of 70% is applied.

  On the other hand, in the black insertion driving shown in (3), a current value that is twice that in normal driving corresponding to 70% luminance is not applied in period a, and a predetermined value (luminance 50%) is subtracted from 70% luminance. A current value corresponding to 20% luminance of the difference is applied. In a period b, a current value corresponding to 50% luminance of a predetermined value is applied.

  As described above, the current value corresponding to the luminance exceeding the predetermined value is applied during the light emission period, and the current value corresponding to the predetermined value is applied during the black insertion period.

  Note that a current value corresponding to a predetermined value may be applied during the light emission period, and a current value corresponding to a luminance component exceeding the predetermined value may be applied during the black insertion period. This is shown in FIG.

  FIG. 7 shows another example in which a current value corresponding to a luminance of 35% is applied instead of white display during normal driving in the period a and the period b. Note that one field period of period c and period d is the same as in FIG. 5, and the normal driving shown in (1) and the conventional black insertion driving shown in (2) are the same as in FIG. Therefore, the description is omitted.

  In the black insertion drive shown in (3), a current value corresponding to 50% luminance of a predetermined value is applied without applying a current value twice that of normal driving corresponding to luminance 70% in period a. In the period b, a current value corresponding to 20% luminance of a difference obtained by subtracting a predetermined value (luminance 50%) from luminance 70% is applied.

  As described above, a current value corresponding to a predetermined value may be applied during the light emission period, and a current value corresponding to a luminance component exceeding the predetermined value may be applied during the black insertion period.

  FIG. 8 and FIG. 9 are diagrams for explaining the black insertion driving in the present embodiment using the output luminance allocation table stored in the storage unit with respect to the input luminance. FIG. 8 shows a gamma correction curve representing luminance-gradation characteristics when γ = 1.0. FIG. 9 shows a gamma correction curve representing luminance-gradation characteristics when γ = 2.2.

  Here, the gamma value γ is an index representing the luminance that changes in accordance with the strength of the input signal. In addition, the intensity of the input signal and the luminance of the screen are not normally in a proportional relationship, and show a gamma characteristic that draws a curve. At this time, an adjustment called gamma correction can be performed to correct a different gamma value for each display. Note that the closer the gamma value is to 1, the more natural the image will be.

  As shown in FIG. 8, when the gamma value is 1, in the black insertion drive, a light emitting frame and a black insertion frame are provided to display lower bits of the video signal input to the control circuit 20. Then, when the most significant bit of the video signal input to the control circuit 20 is 1, light emission of the lower bits is performed in the light emission frame (display for the luminance of C in the figure), and the display unit 13 is light emission in the black insertion frame. What is necessary is just to make it display (the brightness | luminance part of B in a figure). In this way, although the light emission frame is analog driving, the black insertion frame is digital driving for displaying white on the display unit 13 only when the most significant bit is 1.

  Similarly, when the gamma value is 2.2 as shown in FIG. 9, in this black insertion drive, a light emitting frame and a black insertion frame are provided, and only the pixels indicated by the video signal exceeding the luminance of 50% are black. Light is emitted in the insertion frame (display for the luminance E in the figure). At this time, the video signal in the display frame (the luminance component F in the figure) is converted to a value that satisfies gamma based on the LUT shown in FIG.

  However, in the display such as the display unit 13 or the like, the gamma value is not normally 1, so that it is practically as described with reference to FIG. That is, the difference luminance is corrected based on the LUT stored in the storage unit 103.

  FIG. 10 is a flowchart for explaining a black insertion driving method of the organic EL display device according to the embodiment of the present invention.

  First, for example, a video signal of 60 Hz is input to the organic EL display device 100, that is, the image quality conversion circuit 101 of the control unit 10. In order to display an image on the display unit 13, the image quality of the video signal input to the organic EL display device 100 is converted, and the converted video signal is output to the luminance signal determination unit 102.

  Next, the control circuit 20 determines whether or not the luminance of each pixel of the display unit 13 exceeds 50% (predetermined value) from the video signal input by the image quality conversion circuit 101 (S101).

  When the luminance indicated by the video signal of a certain pixel exceeds the luminance 50% (predetermined value) (in the case of Yes in S101), the control circuit 20 determines that the luminance of the corresponding pixel in the display frame is 50% (predetermined). The video signal corresponding to the luminance of the difference obtained by subtracting (value) is converted to γ and displayed (S103). Then, with respect to the corresponding pixel in the black insertion frame, luminance display corresponding to 50% luminance (predetermined value), that is, white display is performed. By doing so, although black display is not performed, the amount of current supplied to the organic EL element included in the pixel portion of the display portion 13 can be suppressed to 50% in the light emission period for displaying the display frame.

  On the other hand, when the luminance indicated by the video signal of a certain pixel is 50% (predetermined value) or less in S101 (in the case of No in S101), the control circuit 20 performs the video signal of that pixel in that pixel in the display frame. Is written in the data line drive circuit 11 to be displayed on the display unit 13 (S107). At that pixel in the black insertion frame, black display is performed as in the conventional black insertion drive.

  As described above, the organic EL display device 100 performs the main black insertion drive.

  As described above, according to the organic EL display device 100 of the present embodiment, in each pixel included in the display unit 13, in each pixel included in the display unit, when the luminance corresponding to the data signal to be written exceeds a predetermined value, within the light emission period. The black insertion driving for increasing the amount of current supplied to the organic EL element of the corresponding pixel whose luminance exceeds a predetermined value is not performed. In the organic EL element of the corresponding pixel, the amount of current supplied to the organic EL element is suppressed to a predetermined value or less during the light emission period, and the insufficient amount of current is supplied to the organic EL element during the black insertion period for black display. Supply. Thus, in a pixel whose luminance exceeds a predetermined value, the luminance is set to a predetermined value by emitting light from the organic EL element that combines the current amount supplied during the light emission period and the current amount supplied during the black insertion period. It is possible to ensure the average luminance of the pixels that exceed. For this reason, not only can the black insertion drive be performed while maintaining the average luminance of the pixels, but also the organic EL element can be prevented from being deteriorated by being loaded with a transient current.

  In the organic EL display device 100, the organic EL element writes a data signal corresponding to a black signal, that is, performs black insertion driving in order to reset the afterimage after the light emission period. As described above, there is a case where the organic EL element emits light even during the black insertion period. However, the chance of causing the organic EL element to emit light during the black insertion period can be reduced by setting a predetermined value. Therefore, it is possible to suppress a reduction in the resolution of moving image display due to an afterimage. That is, it is presumed that the reduction in the resolution of the moving image display due to the organic EL element emitting light during the black insertion period is not a concern due to the way of setting the predetermined value.

  When the organic EL element emits light during the black insertion period, the amount of light emitted by the organic element during the light emission period corresponds to a predetermined value, for example, 50% when the luminance corresponding to the all-white data signal is 100%. The value to be fixed. As a result, the voltage can be set in accordance with the current value of 50%, so that the power consumption can be reduced as compared with the conventional black insertion driving.

  As described above, the organic EL display device of the present invention supplies a display unit having a plurality of pixel units including an organic EL element and a data signal for determining the light emission amount of the organic EL element of each pixel unit to the display unit. A data line driving circuit for performing the above operation, a scanning line driving circuit for controlling writing of the data signal to each pixel portion, a light emission period for causing the organic EL element to emit light, and a black insertion period for which the organic EL element should not emit light. A control unit that emits light from the organic EL element of the pixel unit by controlling the data line driving circuit and the scanning line driving circuit in a display period in which one unit is a unit. When the luminance corresponding to the data signal to be written to the pixel portion in the period exceeds a predetermined value, the data line driving circuit is controlled so that the luminance of the pixel portion exceeding the predetermined value is the emission period. By emitting the organic EL element of the pixel portion allocated to the serial black insertion period, the luminance corresponding to the data signal to be written to the pixel portion in the light emitting period and the black insertion period below a predetermined value.

  Accordingly, it is possible to realize an organic EL display device and a control method thereof that can suppress the shortening of the lifetime of the organic EL element and improve the moving image resolution without reducing the brightness of the image.

  The amount of light emitted from the organic EL element during the light emission period may be 50%, and the amount of light emitted from the light emitting element during the black insertion period may be the remaining percentage. This can produce a large amount of light emission first, and has the effect of making the impression given to the eyes more natural. In this case, in the black insertion frame signal creation unit 105, for example, the luminance of the difference is corrected based on the LUT stored in the storage unit 103, thereby correcting the luminance of the difference. A luminance signal may be created.

  Further, the method of distributing the luminance of the pixel portion (pixel) exceeding the predetermined value into the light emission period and the black insertion period is not limited to the above example. For example, the brightness of the pixel portion exceeding a predetermined value may be uniformly halved.

  Further, although the black insertion period and the light emission period constituting the display period are described as the same time (duty ratio 50%), the present invention is not limited to this. Any duty ratio that can suppress hold blur or the like, that is, can improve the moving image resolution may be used. Even in that case, similarly, in the black insertion period, the organic EL element may emit light so as to have a predetermined luminance value, and the remaining luminance may be emitted in the light emission period. Although it is conceivable that the luminance exceeds a predetermined value during the light emission period, the duty ratio and the predetermined value may be determined in view of the degree of deterioration of the organic EL element.

  As described above, the organic EL display device and the control method thereof according to the present invention have been described based on the embodiment. However, the present invention is not limited to this embodiment. Unless it deviates from the meaning of this invention, the form which carried out the various deformation | transformation which those skilled in the art can think to this embodiment, and the structure constructed | assembled combining the component in different embodiment is also contained in the scope of the present invention. .

  The present invention can be used for an organic EL display device and a control method thereof, and in particular, can be used for an FPD display device such as a television as shown in FIG.

DESCRIPTION OF SYMBOLS 10 Control part 11 Data line drive circuit 12 Scan line drive circuit 13 Display part 20 Control circuit 100 Organic EL display apparatus 101 Image quality conversion circuit 102 Luminance signal determination part 103 Memory | storage part 104 Light emission frame signal creation part 105 Black insertion frame signal creation part 106 Video signal output circuit

Claims (8)

A display unit having a plurality of pixel units each including an organic EL element;
A data line driving circuit for supplying a data signal corresponding to the light emission amount of the organic EL element of each pixel unit to the display unit;
A scanning line driving circuit for controlling writing of the data signal to each of the pixel units;
The data line driving is performed in a display period in which a light emission period in which the organic EL element emits light and a black insertion period in which a data signal corresponding to a black signal is supplied to the organic EL element and the organic EL element does not emit light are set as one unit. A control unit that causes the organic EL element of the pixel unit to emit light by controlling the circuit and the scanning line driving circuit,
The controller is
When the luminance corresponding to the data signal written to the pixel unit in the light emission period exceeds a predetermined value, the luminance corresponds to the luminance indicated by the difference between the luminance of the pixel unit exceeding the predetermined value and the predetermined value in the light emission period. Based on the data signal, the organic EL element of the pixel portion exceeding the predetermined value emits light, and in the black insertion period, the pixel portion of the pixel portion exceeding the predetermined value based on the data signal corresponding to the luminance indicated by the predetermined value. An organic EL display device that emits light from an organic EL element. The organic EL display device further includes a storage unit that stores predetermined data corresponding to a gamma correction curve indicating luminance-gradation characteristics,
The controller is
In the black insertion period, pixels that exceed the predetermined value without performing luminance-gradation correction based on the predetermined data stored in the storage unit for the data signal corresponding to the luminance indicated by the predetermined value The organic EL element of the unit is caused to emit light, and during the light emission period, luminance-gradation correction is performed on the data signal corresponding to the luminance indicated by the difference based on predetermined data stored in the storage unit The organic EL display device according to claim 1, wherein the organic EL element of the pixel unit emits light. The organic EL display device according to claim 1, wherein the predetermined value is a value corresponding to a luminance of 50 percent when the luminance corresponding to the data signal indicating all white is 100 percent. A display unit having a plurality of pixel units each including an organic EL element;
A data line driving circuit for supplying a data signal corresponding to the light emission amount of the organic EL element of each pixel unit to the display unit;
A scanning line driving circuit for controlling writing of the data signal to each of the pixel units;
The data line driving is performed in a display period in which a light emission period in which the organic EL element emits light and a black insertion period in which a data signal corresponding to a black signal is supplied to the organic EL element and the organic EL element does not emit light are set as one unit. A control unit that causes the organic EL element of the pixel unit to emit light by controlling the circuit and the scanning line driving circuit,
The controller is
When the luminance corresponding to the data signal written to the pixel unit in the light emission period exceeds a predetermined value, the pixel unit that has exceeded the predetermined value based on the data signal corresponding to the luminance indicated by the predetermined value in the light emission period. The organic EL element emits light, and in the black insertion period, the pixel portion exceeding the predetermined value is based on a data signal corresponding to the luminance indicated by the difference between the luminance of the pixel portion exceeding the predetermined value and the predetermined value. An organic EL display device that emits light from an organic EL element. The organic EL display device further includes a storage unit that stores predetermined data corresponding to a gamma correction curve indicating luminance-gradation characteristics,
The controller is
In the light emission period, a pixel that exceeds the predetermined value without performing luminance-gradation correction based on predetermined data stored in the storage unit for a data signal corresponding to the luminance indicated by the predetermined value In the black insertion period, luminance-gradation correction based on predetermined data stored in the storage unit is performed on the data signal corresponding to the luminance indicated by the difference during the black insertion period. The organic EL display device according to claim 4, wherein the organic EL element of the pixel portion emits light. The organic EL display device according to claim 4, wherein the predetermined value is a value corresponding to a luminance of 50 percent when the luminance corresponding to a data signal indicating all white is 100 percent. A display unit having a plurality of pixel units each including an organic EL element; a data line driving circuit that supplies a data signal corresponding to the light emission amount of the organic EL element of each pixel unit to the display unit; A scanning line driving circuit that controls writing of a data signal; a light emission period in which the organic EL element emits light; a black insertion period in which a data signal corresponding to a black signal is supplied to the organic EL element and the organic EL element does not emit light; An organic EL display device comprising: a control unit configured to control the data line driving circuit and the scanning line driving circuit to emit light from the organic EL element of the pixel unit in a display period in which a unit is a display period. A control method,
A determination step of causing the control unit to determine whether or not a luminance corresponding to a data signal written to the pixel unit in the light emission period exceeds a predetermined value;
In the determination step, when it is determined by the control unit that the luminance corresponding to the data signal to be written to the pixel unit in the light emission period exceeds a predetermined value, the pixel unit exceeding the predetermined value in the light emission period Based on a data signal corresponding to the luminance indicated by the difference between the luminance of the pixel and the predetermined value, the organic EL element of the pixel portion exceeding the predetermined value is caused to emit light, and in the black insertion period, the luminance corresponding to the predetermined value is represented. And a control step of causing the organic EL elements in the pixel portion exceeding the predetermined value to emit light based on the data signal to be controlled. A display unit having a plurality of pixel units each including an organic EL element; a data line driving circuit that supplies a data signal corresponding to the light emission amount of the organic EL element of each pixel unit to the display unit; A scanning line driving circuit for controlling writing of a data signal, and a black insertion that should not cause the organic EL element to emit light by supplying a data signal corresponding to a light emission period and a black signal for emitting the organic EL element to the organic EL element Control of an organic EL display device comprising: a control unit that controls the data line driving circuit and the scanning line driving circuit to emit light from the organic EL element of the pixel unit in a display period in which the period is one unit. A method,
A determination step of causing the control unit to determine whether or not a luminance corresponding to a data signal written to the pixel unit in the light emission period exceeds a predetermined value;
In the determination step, when the control unit determines that the luminance corresponding to the data signal to be written to the pixel unit in the light emission period exceeds a predetermined value, the light emission period corresponds to the luminance indicated by the predetermined value. The organic EL element of the pixel part exceeding the predetermined value is caused to emit light based on the data signal to be processed, and corresponds to the luminance indicated by the difference between the luminance of the pixel part exceeding the predetermined value and the predetermined value during the black insertion period. A method of controlling an organic EL display device that emits light from an organic EL element in a pixel portion that exceeds the predetermined value based on a data signal to be transmitted.

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