JP2005321684A - Video display apparatus and video display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video display apparatus and a video display method by which a burning phenomenon of an element in an organic EL (electro-luminescence) video display apparatus can be prevented. <P>SOLUTION: Each pixel is provided with a pixel temperature controlling element which controls the pixel temperature. Light is emitted in each pixel based on brightness information (video signals) as well as the pixel temperature controlling element is driven to control brightness deterioration characteristics in each pixel to be uniform. Therefore, such a structure and driving that makes the pixel deterioration uniform in the entire pixels is realized while preventing the brightness deterioration from differing by each pixel depending on the contents of displayed pictures, so as to decrease the burning phenomenon and to keep uniformity for a long period. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to, for example, an active matrix organic EL (electroluminescence) image display device and an image display method thereof, and more specifically, an image display device capable of suppressing a “burn-in phenomenon” caused by a difference in light emission gradation between pixels, and The present invention relates to a video display method.

  In recent years, an organic EL display device using an organic EL element has been developed as one of flat display devices. Since the organic EL display device is a self-luminous type, it does not require a backlight and is excellent in moving image characteristics, a wide viewing angle, color reproducibility, and the like, and thus has attracted attention as a next-generation thin display.

  By the way, the luminance of an organic EL (electroluminescence) element deteriorates as it is used, and when a constant display is continued, a uniformity deterioration called “burn-in” occurs. Further, in an image display device capable of color display having R (red), G (green), and B (blue) independent organic EL elements, if RGB is not used evenly, deterioration occurs for each RGB color, and white A phenomenon of imbalance occurs. This symptom is irreversible, and if it progresses, the video display quality will deteriorate significantly.

  In order to suppress the “burn-in phenomenon” in the organic EL video display device, conventionally, the display time is limited, the display content of the video is changed (see Patent Documents 1 and 2 below), and the display position is moved (see Patent Document 3 below). ) Or a display of a corrected image during a non-use time (see Patent Documents 4 and 5 below), and other measures are taken to prevent non-uniformity in luminance deterioration characteristics between pixels.

JP 2000-221908 A JP 2002-207475 A JP 2003-223160 A JP 2003-228329 A JP 2003-295827 A

  However, in the conventional organic EL video display device with the above-described measures for preventing burn-in, the occurrence of non-uniformity in luminance deterioration is suppressed by the time limit of the same display, etc. Will be forced.

  As a result, in the configurations disclosed in Patent Documents 1 to 3 and the like, even if the user wants to see the same display for a long time, a display change that is not assumed by the user is suddenly made. There is a risk of inducing an erroneous operation. In addition, in the configurations of Patent Documents 4 and 5, an image that is not intended by the user is displayed even when it is not in use, causing the user to be confused or confused, resulting in misidentification such as a failure. There is a risk of causing.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a video display device and a video display method capable of preventing image sticking and color misregistration without causing confusion or misunderstanding of the user.

  In solving the above problems, an image display device of the present invention controls a pixel temperature adjusting element that is arranged for each pixel and adjusts the pixel temperature, and controls driving of the pixel temperature adjusting element based on luminance information. And a drive control unit that equalizes the luminance deterioration characteristics of the display.

  Also, the image display method of the present invention is provided with a pixel temperature adjusting element that adjusts the pixel temperature for each pixel, and at the same time, the pixel temperature adjusting element is driven to emit light based on the luminance information, and the luminance of each pixel is driven. It is characterized by making the deterioration characteristics uniform.

  For example, one of the causes of pixel deterioration of an organic EL element is the vitrification of the structure due to the temperature rise of the pixel. Therefore, the present invention realizes a structure and driving that makes the pixel deterioration uniform for all pixels so that deterioration due to vitrification does not differ from pixel to pixel depending on the content of the display image, thereby reducing and uniforming the burn-in phenomenon. I try to maintain long-term sex.

  As the temperature adjusting element, a heating element provided in the vicinity of the light emitting element can be used. By the heat generation operation of the light emitting element by the heat generating element, the luminance deterioration of the light emitting element can be promoted, and the deterioration can be made uniform for each pixel. For the heating element, a resistance heating body or the like that can control the amount of heat generation according to the magnitude of the energized current is suitable.

  In addition to the heat generation operation of the light emitting element, or in place of the heat generation operation of the light emitting element, the pixel temperature is cooled by performing an endothermic (heat dissipation) operation on the light emitting element that emits light with relatively high luminance. It may be. As a result, it is possible to reduce the deterioration amount of each pixel and to improve the lifetime of the element. As the heat absorption element, a Peltier element or the like whose heat absorption amount can be controlled by the magnitude of a current to be energized is preferably used.

  As a reference for luminance deterioration control of each pixel, that is, a control target of pixel temperature, a control method based on a predetermined gradation degree such as a gradation of 100% or 50% can be applied, but is not limited thereto.

  For example, a video display device realizes video display by emitting light with an intensity corresponding to a supplied video signal, and a video is obtained by changing the display in units of frames or fields. At this time, the maximum light emission intensity of the light emitting element in an arbitrary video display unit (for example, a field) can be known in advance from the input video signal. It is possible to detect this value, determine an appropriate amount of deterioration in the field, and control the amount of deterioration of the light emitting element by driving and controlling the temperature adjusting element in units of fields. Thereby, it is possible to contribute to the improvement of the life of the light emitting element while maintaining the uniformity of display.

  In addition, as a light emitting element, not only an organic EL light emitting element but other self light emitting elements, such as a light emitting diode, are applicable.

  As described above, according to the present invention, even if characters, symbols, images, etc. are displayed with their display positions fixed, it is possible to suppress the burn-in phenomenon, so that the conventional burn-in prevention measures This eliminates the need to move or erase the display position, thereby enabling long-term video viewing without causing user confusion or misoperation, and changing the white balance (color shift) even after prolonged use. Can be eliminated.

  Embodiments of the present invention will be described below with reference to the drawings. In each of the following embodiments, an organic EL active matrix video display device using an organic EL element as a light emitting element constituting each pixel will be described as an example.

[First Embodiment]
FIG. 1 is a block diagram showing a schematic configuration of the first embodiment of the present invention. The organic EL light emitting layer 1 is a self light emitting element that is disposed between the anode electrode 2 and the cathode electrode 3 and emits light with a light emission intensity corresponding to the magnitude of the current supplied from the display drive current source 4. In the vicinity of the organic EL light emitting layer 1, a heat generating layer 5 as a pixel temperature adjusting element is disposed between the anode electrode 2 and the cathode electrode 6, depending on the magnitude of the current supplied from the heat generating layer driving current source 7. The organic EL light emitting layer 1 generates heat with the generated heat amount. In the present embodiment, the heat generating layer 5 is laminated on the organic EL light emitting layer 1.

  The heat generating layer 5 is preferably formed of a transparent surface heating element film such as an ITO (Indium Tin Oxide) film. For example, a transparent conductive film “OTEC” manufactured by Toby Corporation is applicable. It is.

  The display drive current source 4 drives the organic EL light emitting layer 1 with a current amount corresponding to the display drive current control signal S1 supplied from the drive control circuit (drive control unit of the present invention) 8. The display drive current control signal S1 is generated by the drive control circuit 8 based on the video signal (luminance information) input to the drive control circuit 8. The heat generation layer drive current source 7 drives the heat generation layer 5 with a current amount corresponding to the heat generation layer drive current control signal S2 supplied from the drive control circuit 8. The heat generation layer drive current control signal S2 is also generated by the drive control circuit 8 based on the video signal (luminance information) input to the drive control circuit 8.

  By the way, the lifetime of the organic EL element depends on its emission gradation and element temperature.

  FIG. 2 shows an example of the dependence characteristic of the light emission gradation on the lifetime of the organic EL element. In the figure, life curves at 50% gradation (curve A) and 100% gradation (curve B) are shown. The vertical axis represents the relative luminance when the initial luminance is 1, and the horizontal axis represents the light emission time. As is apparent from the figure, the relative luminance is deteriorated faster at 100 gradations than at 50% gradation. That is, the organic EL element has a characteristic that the deterioration rate increases as the gradation is increased.

  FIG. 3 shows an example of the dependence characteristic of the substrate temperature on the lifetime of the organic EL element. In the figure, life curves at 25 ° C. (curve A) and 50 ° C. (curve B) are shown. The vertical axis represents the relative luminance when the initial luminance is 1, and the horizontal axis represents the light emission time. As is clear from the figure, the relative luminance deteriorates faster at 50 ° C. than at 25 ° C. That is, the organic EL element has a characteristic that the deterioration rate increases as the temperature is increased.

  The “burn-in” phenomenon in the organic EL video display device is caused by displaying images having different light emission gradations between pixels for a long time. FIG. 4 is a graph in which deterioration curve examples at the time of 10% gradation (curve C), 50% gradation (curve A), and 100% gradation (curve B) are plotted on the same graph. As described above, since the degree of deterioration increases as the gradation increases, for example, at the light emission time T1, the luminance difference corresponding to the relative luminance difference ΔL1 between the 10% gradation and the 100% gradation is “burn-in”. Will appear as.

  In view of this, the video display device according to the present embodiment is inputted by forming a plurality of pixels 10 including the organic EL light emitting layer 1 and the heat generating layer 5 shown in FIG. The display drive current is controlled so that an appropriate amount of carriers is injected into the organic EL light emitting layer 1 in accordance with the video signal to be generated, and at the same time, the heat generation layer 5 so that the degree of deterioration does not fall below the device design value according to the display drive current. The amount of deterioration is compensated for, and control is performed so that the amount of deterioration with respect to the usage time is as designed. In other words, the drive control circuit 8 drives and controls the light emitting layer 1 and the heat generating layer 2 by the above-described method so as not to cause a difference in the degree of deterioration of each pixel in accordance with the input signal, thereby maintaining the uniformity of the entire screen. To act.

  FIG. 5 shows an example of pixel luminance deterioration control according to this embodiment. Heat generation processing is not performed on pixels that emit light at 100% gradation. For a pixel that emits light at 50% gradation, a heat generation amount UQ1 whose deterioration characteristic changes from curve A to A1 is given, and for a pixel that emits light at 10% gradation, the deterioration characteristic changes from curve C to C1. A changing calorific value UQ2 is given (UQ1 <UQ2). Thereby, the relative luminance difference between the 10% gradation pixel and the 100% gradation pixel at the light emission time T1 becomes ΔL2, which can be made smaller than the relative luminance difference ΔL1 when the deterioration control is not performed as shown in FIG. “Burn-in” can be improved.

  The relative luminance difference ΔL2 that is a control target is preferably as small as possible. However, the size is not particularly limited, and is appropriately set according to the type of the organic EL light emitting layer to be used, the display control mode of the display image, and the like.

  Next, details of the pixel 10 will be described with reference to FIGS. 6 and 7. FIG. 6 shows the configuration of the organic EL video display device 11 of the present embodiment, and FIG. 7 shows the configuration of the pixel circuit 10A per pixel.

  The organic EL video display device 11 includes an organic EL display unit 12 in which a plurality of pixels 10 are arranged in a matrix, a drive control circuit 8 that also serves as a data line drive circuit and a heat generation layer drive circuit, and a write scan drive circuit 9. It has. As shown in the drawing, a plurality of write scanning lines X (X1, X2,..., Xn) are arranged in rows, and a plurality of data lines Y (Y1, Y2,..., Yn) are arranged in columns. Pixels 10 are arranged at the intersections between the write scanning lines X and the data lines Y, respectively.

  The write scan line X is connected to the write scan drive circuit 9. The write scan drive circuit 9 includes a shift register and is supplied with a vertical clock VCK and a vertical start pulse VSP. Then, by sequentially transferring the vertical start pulse VSP in synchronization with the vertical clock VCK, the write scanning lines X1, X2,..., Xn are sequentially selected within one scanning cycle.

  On the other hand, the data line Y is connected to the drive control circuit 8. Luminance information (video signal) DATA is input to the drive control circuit 8. The drive control circuit 8 outputs an electrical signal corresponding to the luminance information of each data line Y in synchronization with the line sequential scanning of the writing scanning line X. In this case, the drive control circuit 8 may perform so-called line-sequential driving to supply electric signals to selected pixel rows all at once, or may perform so-called dot-sequential driving to select selected pixels. The electrical signals may be sequentially supplied to the rows. In any case, the present invention includes both line-sequential driving and point-sequential driving.

  As shown in FIG. 7, the pixel circuit 10A constituting each pixel 10 includes an organic EL light emitting layer 1, a heat generating layer 5, a data line Y, a write scanning line X, an EL current supply line 13, The heating layer current supply line 14, the write scanning transistor 15, the EL driving transistor 16, the heating layer driving transistor 17, and the storage capacitor 18 are electrically connected as shown in the figure. The EL drive transistor 16 is a P-channel MOSFET (Metal Oxide Semiconductor Field-Effect Transistor), and the heat generation layer drive transistor 17 is an N-channel MOSFET.

  When writing data to the pixel 10, the write scanning line X is set to H (High) level, and the write scanning transistor 15 is turned on. At this time, the data line Y is connected to the gate of the EL drive transistor 16 and the gate of the heat generation layer drive transistor 17. As the potential of the data line Y is lower, the voltage between the source and the gate of the EL drive transistor 16 increases, and the current flowing through the source and drain of the EL drive transistor 16, that is, the drive current of the organic EL light emitting layer 1 increases. The emission intensity increases. On the other hand, the voltage between the source and the gate of the heat generating layer driving transistor 17 is reduced, and the current flowing through the source and drain of the heat generating layer driving transistor 17, that is, the current flowing through the heat generating layer 5 is reduced. The calorific value becomes smaller. Note that the heat generating action of the heat generating layer 5 is held by the holding capacitor 18 for one scanning period.

  Therefore, the organic EL light emitting layer 1 has a small heat generation amount when the light emission intensity is high, and a large heat generation amount when the light emission intensity is low. Thereby, by adjusting the source potential of the heat generating layer driving transistor 17 and appropriately setting the potential of the gate voltage threshold (Vth) of the heat generating layer driving transistor 17, the luminance deterioration due to the EL emission intensity and the luminance due to the temperature are set. The total deterioration can be made constant regardless of the light emission intensity, and uniformity of deterioration between pixels can be maintained.

  For example, as in the deterioration control example shown in FIG. 5, with reference to the deterioration characteristic of a pixel that emits light at 100% gradation, by energizing the heat generating layer 5 to a pixel that emits light at a lower gradation than this, An appropriate amount of heat is generated in the organic EL light-emitting layer 1, and drive control can be performed to approximate the deterioration characteristic curve of the organic EL light-emitting layer 1 to the deterioration characteristic curve at 100% gradation.

  It should be noted that the present invention is not limited to the case where heat generation processing is performed on other relatively low-luminance pixels based on 100% gradation, and other gradations such as 50% gradation are used as a reference, for example, for each field. If the maximum luminance of all pixels in a certain period is used as a reference, the deterioration degree of each pixel can be reduced while maintaining the uniformity of deterioration, so that the overall life can be improved.

  As described above, according to the present embodiment, even if characters, symbols, images, etc. are displayed with their display positions fixed, “burn-in” can be suppressed. There is no need to move or erase the display position, so that users can watch the video for a long time without causing confusion or misoperation, and the change in white balance can be eliminated even after long-term use. .

  In addition, according to the present embodiment, it is not necessary to move or erase the display position as a conventional “burn-in” prevention measure, so that it is possible to realize a design as intended by the designer and control. For example, when it is controlled by software, the cause of bugs can be reduced and quality can be improved.

[Second Embodiment]
8 and 9 show a second embodiment of the present invention. Here, FIG. 8 shows the configuration of the organic EL video display device 21 of the present embodiment, and FIG. 9 shows the configuration of the pixel circuit 10B per pixel.

  The organic EL video display device 21 includes an organic EL display unit 22, a data line drive circuit 23, a write scan drive circuit 24, and a heat generation layer drive control circuit (drive control unit of the present invention) 25, which is illustrated. Thus, a plurality of write scan lines X connected to the write scan drive circuit 24 are arranged in rows, and a plurality of data lines Y connected to the data line drive circuit 23 are arranged in columns. In addition, a plurality of heat generating layer data lines Z (Z1, Z2,..., Zn) connected to the heat generating layer drive control circuit 25 are arranged in parallel with the data lines Y. Further, the display line luminance information DATA1 is supplied to the data line drive circuit 23, and the heat generation layer drive luminance information DATA2 is supplied to the heat generation layer drive control circuit 25.

  As shown in FIG. 9, the pixel circuit 10B constituting each pixel 10 includes an organic EL light emitting layer 1, a heat generation layer 5, a write scanning line X, a data line Y, and a heat generation layer data line Z. EL current supply line 26, heat generation layer current supply line 27, EL write scanning transistor 28, EL drive transistor 29, heat generation layer drive transistor 30, EL storage capacitor 31, and heat generation layer write scan transistor. 32 and a heat generating layer storage capacitor 33, which are electrically connected as shown in the figure. The EL drive transistor 29 and the heat generation layer drive transistor 30 are each a P-channel MOSFET.

  When writing data to the pixel 10, the write scan line X is set to H level, and the EL write scan transistor 28 and the heat generation layer write scan transistor 32 are turned on. At this time, the data line Y and the gate of the EL drive transistor 29 are connected, and the heat generation layer data line Z and the gate of the heat generation layer drive transistor 30 are connected. As the potential of the data line Y is lower, the voltage between the source and the gate of the EL drive transistor 29 increases, and the current flowing through the source and drain of the EL drive transistor 29, that is, the drive current of the organic EL light emitting layer 1 increases. , The emission luminance increases. Further, the higher the potential of the heat generating layer data line Z, the smaller the voltage between the source and the gate of the heat generating layer driving transistor 30, and the current flowing through the source and drain of the heat generating layer driving transistor 30, that is, the current flowing through the heat generating layer 5. By decreasing, the amount of heat generated from the heat generating layer 5 decreases.

  Therefore, the organic EL light emitting layer 1 has a small heat generation amount when the light emission intensity is high, and a large heat generation amount when the light emission intensity is low. Thus, by appropriately setting the signals DATA1 and DATA2 for controlling the respective potentials of the data line Y and the heat generation layer data line Z, the sum of the luminance deterioration due to EL emission intensity and the luminance deterioration due to temperature is related to the emission intensity. Therefore, it is possible to maintain the uniformity of deterioration between pixels.

  With this configuration, for example, as in the deterioration control example shown in FIG. 5, the heat generation layer 5 is provided for pixels that emit light at lower gradations based on the deterioration characteristics of pixels that emit light at 100% gradation. When the current is applied, the organic EL light-emitting layer 1 generates an appropriate amount of heat, and the drive control for approximating the deterioration characteristic curve of the organic EL light-emitting layer 1 to the deterioration characteristic curve at 100% gradation is possible. The same effect as the form can be obtained.

[Third Embodiment]
10 to 12 show a third embodiment of the present invention. Here, FIG. 10 is a sectional view schematically showing the pixel structure, FIG. 11 is a configuration diagram of a pixel circuit per pixel, and FIG. 12 is a diagram showing an example of pixel deterioration control.

  As shown in FIG. 10, the pixel structure of the organic EL video display device in the present embodiment has a heat absorbing layer 36, a first insulating film 37, a heat generating layer 5, a second insulating film 38, and an anode electrode 39 on a glass substrate 35. The organic EL light emitting layer 1, the cathode electrode 40, the sealing material 41, and the sealing glass 42 are laminated in this order.

  The endothermic layer 36 is composed of a Peltier element having a heat generating metal layer 43 made of Al or the like, a Si layer 44 in which P and N channels are alternately arranged, and a heat generating metal layer 45 made of Al or the like. . The first and second insulating films 37 and 38 are made of, for example, SiN, SiO 2 or the like, and the anode electrode 39 is made of a low resistance metal such as silver. The heat generating layer 5 is made of, for example, low resistance ITO by an ion plating method or the like.

  The heat absorption layer 36 to the anode electrode 39 are formed by a TFT (Thin Film Transistor) process, the organic EL light emitting layer 1 having a multilayer structure and the cathode electrode 40 are formed by an EL process such as vapor deposition, and the sealing material 41 and the sealing material 41 are sealed. The stop glass 42 is formed by a sealing process. The cathode electrode 40 extracts light emitted from the organic EL light-emitting layer 1 by top emission through the cathode electrode 40, for example, by forming a MgAg-based translucent metal by vapor deposition or the like.

  Next, the configuration of the pixel circuit 46 for driving the pixel having the configuration shown in FIG. 10 will be described with reference to FIG.

  The pixel circuit 46 includes an organic EL light emitting layer 1, a heat generation layer 5, a write scan line X, a data line Y, an EL current supply line 47, a heat generation layer current supply line 48, and a write scan transistor 49. The EL drive transistor 50, the heat generation layer drive transistor 51, the storage capacitor 52, the Peltier element 36, and the Peltier drive transistor 53 are electrically connected as shown in the figure. The EL drive transistor 50 is a P-channel MOSFET, the heat generating layer drive transistor 51 is an N-channel MOSFET, and the Peltier drive transistor 53 is a P-channel MOSFET.

  When writing data to the pixel, the write scanning line X is set to H level, and the write scanning transistor 49 is turned on. At this time, the data line Y is connected to the gate of the EL drive transistor 50, the gate of the heat generation layer drive transistor 51, and the gate of the Peltier drive transistor 53. As the potential of the data line Y is lower, the voltage between the source and the gate of the EL drive transistor 50 increases, and the current flowing through the source and drain of the EL drive transistor 50, that is, the drive current of the organic EL light emitting layer 1 increases. , The emission luminance increases. On the other hand, the voltage between the source and the gate of the heat generating layer driving transistor 51 is reduced, and the current flowing through the source and drain of the heat generating layer driving transistor 51, that is, the current flowing through the heat generating layer 5 is reduced. The calorific value becomes smaller. Further, the voltage between the source and the gate of the Peltier drive transistor 53 increases, the current flowing through the source and drain of the Peltier drive transistor 53, that is, the drive current of the Peltier element 36 increases, and the endothermic effect increases.

  Therefore, the luminance deterioration characteristic of the organic EL light emitting layer 1 can be controlled by appropriately adjusting the heat generation amount of the heat generating layer 5 or the heat absorption amount of the Peltier element 36 according to the light emission luminance of the organic EL light emitting layer 1. It becomes possible. Thereby, as shown in FIG. 12, for example, the degree of luminance deterioration of the organic EL light emitting layer 1 can be controlled within a certain range.

  FIG. 12 shows an example of pixel luminance deterioration control according to this embodiment. Neither exothermic nor endothermic processes are performed on pixels that emit light at 50% gradation (curve A). For a pixel that emits light at 10% gradation, a heat generation amount UQ3 whose luminance deterioration characteristic changes from curve C to C2 is given, and for a pixel that emits light at 100% gradation, the luminance deterioration characteristic changes from curve B to B2. Gives the endothermic amount DQ1. As a result, the relative luminance difference between the 10% gradation pixel and the 100% gradation at the light emission time T1 can be reduced to ΔL3, and the luminance deterioration characteristic of each pixel can be made uniform to suppress the burn-in phenomenon. become.

  In this example, the pixel temperature is adjusted and controlled in accordance with the luminance deterioration characteristic at the 50% gradation with reference to the gradation of 50%. However, the present invention is not limited to this. The average gradation may be used as a reference.

[Fourth Embodiment]
In the fourth embodiment of the present invention, the maximum value component is detected from the luminance information supplied to each pixel in the field unit (or frame unit), and the luminance deterioration characteristic of the pixel corresponding to the detected maximum luminance information. A configuration of a video display device having a mechanism for adjusting the pixel temperature of other pixels according to the above will be described.

  FIG. 13 is a block diagram of the pixel temperature adjusting mechanism in the present embodiment. The organic EL drive circuit 55 drives the organic EL light emitting layer of each pixel 56 with light emission intensity corresponding to the input video signal (luminance information). At the same time, the in-field maximum emission intensity detection circuit 57 detects the maximum emission information from the input video signal and supplies the detected maximum emission information to the deterioration amount setting circuit 58. The in-field maximum emission intensity detection circuit 57 and the deterioration amount setting circuit 58 constitute a drive control unit of the present invention.

  The deterioration amount setting circuit 58 supplies a deterioration control signal to the pixel temperature adjusting element of each pixel, and raises the pixel temperature that emits light at other low luminance with reference to the luminance deterioration characteristic of the pixel that emits light at the maximum light emission intensity. Promotes the amount of luminance degradation. Alternatively, the pixel temperature is cooled by the endothermic (heat dissipation) action of the pixel that emits light at the maximum light emission intensity to suppress the luminance deterioration amount, and the pixel temperature of the other light emitting pixel is set based on the suppressed luminance deterioration characteristic. You may make it adjust. In the latter case, the pixel that is the target of heat absorption may be limited to a pixel that emits light with a luminance greater than a predetermined value.

  FIG. 14A shows EL emission intensity (solid line) with respect to video signal input of the organic EL light emitting layer, and heat generation control (dashed line) and heat absorption control (one point) for the organic EL light emitting layer in order to keep the luminance deterioration level constant accordingly. It is a timing chart which shows the mode of a chain line. When the EL emission intensity is higher than a predetermined value, the deterioration is suppressed by heat absorption control, and when the EL emission intensity is low, the deterioration is accelerated by heat generation control. Thereby, it is possible to realize a certain deterioration regardless of the light emission intensity of the organic EL light emitting layer.

  Note that the reference for the heat generation control is based on pixels that emit light at other maximum luminances, but of course, this is not a limitation, and the average luminance information of all the pixels in one field is detected, and the deterioration characteristics of the average values are used. You may make it match. Further, the endothermic control can be performed in the same manner.

  FIG. 14B is an enlarged view of a part of FIG. 14A in the time axis direction. Video display realizes a moving image by changing the light emission intensity in units of frames or fields. FIG. 14B shows the state of organic EL emission intensity and the accompanying heat generation and heat dissipation control for each video rewriting unit (field in this example).

  According to the present embodiment, since the peak detection of the video signal is performed for each field and the organic EL pixel deterioration amount is optimized, for example, the front black screen is displayed for a long time. When the intensity is almost zero, the luminance deterioration amount due to heat generation can be reduced to zero. As a result, the lifetime characteristic of the element can be improved as compared with the case where the luminance deterioration control is performed based on a predetermined gradation.

  For example, FIG. 15 shows the luminance deterioration characteristic (100% luminance) when the maximum emission intensity in the field is not taken into account and the luminance deterioration characteristic when the luminance deterioration optimization control is performed by detecting the maximum emission intensity in the field. . As is apparent from the figure, by performing luminance deterioration optimization control, it is possible to suppress the luminance deterioration gradient when the maximum in-field emission intensity is not 100% luminance, and to improve the element lifetime.

  As mentioned above, although each embodiment of this invention was described, of course, this invention is not limited to these, A various deformation | transformation is possible based on the technical idea of this invention.

  For example, in the above embodiment, the example in which the heat generating layer 5 is laminated on the lower surface side of the organic EL light emitting layer 1 has been described. Instead, the heat generating layer is disposed in the same plane as the organic EL element. Is also possible. For example, as shown in FIG. 16, the organic EL light emitting layer 60 for one pixel is constituted by the organic EL elements 61, 62, and 63, and the heating elements 64 and 65 are adjacently disposed between these organic EL elements 61 to 63. be able to. In addition to this, any structure can be adopted as long as the arrangement structure can reduce the temperature difference between the heat generating layer and the light emitting layer.

  Further, in the above embodiment, the luminance deterioration characteristics are made uniform for all the pixels constituting the organic EL display unit (panel), but instead of this, for example, FIG. 17 and FIG. As shown in the figure, the entire panel may be divided into a plurality of regions, and brightness deterioration uniformity control may be performed for each of the divided regions.

  As shown in FIG. 17, when the whole area is divided by the size of the region R1, the amount of heat generation is determined for each region R1, for example, based on the maximum luminance for each field. In this case, when compared with the maximum brightness of the entire panel area, the maximum brightness is reduced for each area as long as it is not a raster, and the overall heat generation amount can be reduced. As shown in FIG. 18, when the region R2 is further divided, the maximum luminance for each region becomes smaller, and the overall heat generation amount can be reduced.

  When the control is divided for each area as in these examples, the degree of deterioration differs for each area. However, since the degree of deterioration is averaged for each area, it is possible to reduce the degree of image sticking. Become.

It is a block diagram which shows schematic structure of the 1st Embodiment of this invention. It is a figure which shows an example of the dependence characteristic of the light emission gradation with respect to the lifetime of an organic EL element. It is a figure which shows an example of the dependence characteristic of the substrate temperature with respect to the lifetime of an organic EL element. It is the figure which plotted the example of a degradation curve at the time of 10% gradation, 50% gradation, and 100% gradation on the same graph. It is a figure which shows an example of the luminance degradation control of the pixel by the 1st Embodiment of this invention. 1 is a schematic configuration diagram of an organic EL video display device according to a first embodiment of the present invention. It is a figure which shows the structure of the pixel circuit per pixel of the organic electroluminescent video display apparatus shown in FIG. It is a schematic block diagram of the organic electroluminescent image display apparatus by the 2nd Embodiment of this invention. It is a figure which shows the structure of the pixel circuit per pixel of the organic electroluminescent video display apparatus shown in FIG. It is a figure which shows typically the pixel structure in the 3rd Embodiment of this invention. It is a figure which shows the structure of the pixel circuit per pixel of the 3rd Embodiment of this invention. It is a figure which shows an example of the deterioration control of the pixel in the 3rd Embodiment of this invention. It is a block diagram of the pixel temperature adjustment mechanism in the 4th Embodiment of this invention. It is a timing chart which shows the mode of the heat_generation | fever control and heat absorption control with respect to the organic electroluminescent light emitting layer by the 4th Embodiment of this invention. It is a figure which shows the luminance deterioration characteristic (100% luminance) when not considering the maximum light emission intensity in the field, and the luminance deterioration characteristic when the luminance deterioration optimization control is performed by detecting the maximum light emission intensity in the field. It is a top view which shows the modification of the arrangement structure of the organic electroluminescent light emitting layer and heat generating layer in this invention. It is a figure explaining the modification of the luminance degradation control method in this invention. It is a figure explaining the modification of the luminance degradation control method in this invention similarly to FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Organic EL light emitting layer, 5 ... Heat generation layer, 8 ... Drive control circuit, 9 ... Write scanning control circuit, 10 ... Pixel, 10A, 10B, 46 ... Pixel circuit, 11, 21 ... Organic EL video display device, 12 22 ... Organic EL display unit, 23 ... Data line drive circuit, 24 ... Write scanning control circuit, 25 ... Heat generation layer drive control circuit, 35 ... Glass substrate, 36 ... Peltier element, 42 ... Sealing glass, 57 ... Field Inner maximum emission intensity detection circuit, 58... Deterioration amount setting circuit, X... Scanning line, Y... Data line, Z.

Claims (10)

A scanning line that selects a pixel in a predetermined scanning cycle, a data line that provides luminance information for driving the pixel, and a pixel circuit that controls the amount of current based on the luminance information and causes the light emitting element to emit light. In an active matrix video display device arranged in a shape,
A pixel temperature adjusting element arranged for each pixel to adjust the pixel temperature;
An image display apparatus comprising: a drive control unit that controls driving of the pixel temperature adjusting element based on the luminance information and uniformizes luminance deterioration characteristics of each pixel. The video display device according to claim 1, wherein the pixel temperature adjusting element is a heat generating element and / or a heat absorbing element provided in the vicinity of the light emitting element. The video display device according to claim 1, wherein the pixel temperature adjusting element is stacked on the light emitting element. The video display device according to claim 1, wherein the pixel temperature adjusting element is disposed adjacent to the surface of the light emitting element. The drive control unit detects a maximum emission intensity information from luminance information supplied to each pixel for each scanning cycle, and controls the pixel temperature adjustment element based on an output of the detection circuit unit The video display device according to claim 1, further comprising: a setting circuit unit that sets an amount. The video display device according to claim 1, wherein the light emitting element is an organic electroluminescence element. A scanning line for selecting a pixel in a predetermined scanning cycle, a data line for supplying luminance information for driving the pixel, and a pixel circuit for controlling the amount of current based on the luminance information and causing the light emitting element to emit light are arranged in a matrix. In an image display method that is arranged and performs light emission operation of the light emitting element based on selective scanning of the operation line by a scanning driving unit and selection driving through the data line by a data driving unit,
Provide a pixel temperature adjustment element that adjusts the pixel temperature for each pixel,
A video display method, wherein each pixel is caused to emit light based on the luminance information, and at the same time, the pixel temperature adjusting element is driven to equalize luminance deterioration characteristics of each pixel. The video display method according to claim 7, wherein the uniform luminance deterioration characteristic between the pixels includes promotion of luminance deterioration due to a heat generation operation of the light emitting element. The video display method according to claim 7, wherein the uniform luminance deterioration characteristic between the pixels includes suppression of luminance deterioration by a heat absorbing element of the light emitting element. Detecting the maximum light emission intensity information in one scanning cycle, and adjusting the pixel temperature of other pixels by driving the pixel temperature adjusting element so as to correspond to the luminance deterioration characteristic of the pixel emitting light at the maximum light emission intensity. 8. The video display method according to claim 7, wherein

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