JP2010139836A - Image display device and driving method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remarkably improve accuracy in prediction of luminance deterioration as compared with the conventional manner by using an active matrix image display device employing organic EL elements. <P>SOLUTION: Regarding a constitution to correct image data gradation and to correct the luminance, the deterioration amount of each pixel is detected from a deterioration amount obtained by converting to a display time on a master deterioration curve, and then, the luminance is corrected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image display device and a driving method of the image display device, and can be applied to an active matrix image display device using a self-luminous element such as an organic EL (Electro Luminescence) element. The present invention predicts the deterioration amount of each pixel based on the deterioration amount converted to the display time on the master deterioration curve and corrects the light emission luminance, thereby significantly improving the prediction accuracy of the light emission luminance deterioration compared to the conventional case. improves.

  In recent years, active matrix image display devices using organic EL elements have been actively developed. Here, the organic EL element is a current-driven self-luminous element in which light emission luminance is expressed by a multiplication value of light emission efficiency and drive current. An active matrix type image display device using an organic EL element has a pixel circuit formed by an organic EL element and a drive circuit that drives the organic EL element arranged in a matrix to form an image display unit that is an effective pixel region, A desired image is displayed on the image display unit.

  However, as the organic EL element is used for a long time, the light emission efficiency decreases. In addition, the organic EL element has gradation dependency on the rate of decrease in the luminous efficiency, and the higher the emission luminance, the faster the decrease in the luminous efficiency. Accordingly, in an image display device using an organic EL element, emission luminance decreases and chromaticity changes due to long-term use. In addition, when a still image having a high contrast is displayed for a long time, so-called burn-in occurs. Therefore, for example, Japanese Patent Application Laid-Open No. 2007-156044 discloses a configuration for preventing a decrease in light emission luminance.

  Here, according to the technique disclosed in Japanese Patent Application Laid-Open No. 2007-156044, a monitor organic EL element (hereinafter referred to as a dummy organic EL element) and a light receiving element are provided in a portion other than the image display unit. In this method, a decrease in light emission luminance in the dummy organic EL element is detected using a light receiving element. Further, using this detection result, the deterioration amount when the organic EL element is driven at each gradation is predicted. Further, using this prediction result, a decrease in the light emission luminance of the organic EL element provided in the image display unit is predicted based on the gradation of the organic EL element provided in the image display unit. Further, the gradation of the image data is corrected based on the prediction result to correct the decrease in light emission luminance.

  That is, as shown in FIG. 6, the light emission luminance y of the organic EL element when light is emitted at a predetermined gradation L can be expressed by the following equation. Here, t is the light emission time. Further, g (L, Lo) is a function for obtaining a deterioration rate when light is emitted at gradation L from a decrease rate of light emission luminance when light is emitted at gradation Lo. It is a deterioration rate conversion function showing gradation dependency. Accordingly, the deterioration rate conversion function g (L, Lo) increases in value as the gradation L increases. y = f (t, Lo) is a reference deterioration curve used for correcting the light emission luminance, and is hereinafter referred to as a master deterioration curve. Further, y = f (t, L) is referred to as a gradation curve of gradation L. In FIG. 6, the light emission luminance y is normalized and shown.

The technique disclosed in Japanese Patent Application Laid-Open No. 2007-156044 is based on the relationship of the formula (1), and the amount of deterioration of the emission luminance (1-f (t, Lo)) detected by the dummy organic EL element is The deterioration rate conversion function g (L, Lo) is multiplied to predict the emission luminance deterioration amount (1-f (t, L)) when the organic EL element is driven at each gradation. Further, the prediction result is selected according to the gradation of the organic EL element provided in the image display unit, and a decrease in light emission luminance in each pixel is predicted.
JP 2007-156044 A

  However, the method disclosed in Japanese Patent Application Laid-Open No. 2007-156044 has a problem that is still insufficient in practice in terms of prediction accuracy.

  In particular, when a decrease in light emission luminance at each gradation is predicted using the relationship of equation (1), the master deterioration curve y = f (t, Lo) is vertical by the deterioration rate conversion function g (L, Lo). The deterioration curve y = f (t, L) of the gradation L is obtained by expanding and contracting in the axial direction. Therefore, when the emission luminance y due to the master deterioration curve y = f (t, Lo) approaches the value 0 due to the increase in time t, the deterioration curve y = f (t, L) of the gradation L larger than the gradation Lo becomes The value may be 0 or less. Therefore, in the conventional method, a physical contradiction occurs.

  In the method disclosed in Japanese Patent Application Laid-Open No. 2007-156044, the deterioration amount is predicted by selecting a deterioration curve based on a change in gradation of the organic EL element provided in the image display unit. Therefore, when the deterioration amount becomes equal at a predetermined point in time and there are a plurality of organic EL elements driven at the same gradation, it is impossible to guarantee that the deterioration amounts of the plurality of organic EL elements are equal. Will occur. Also in this case, the conventional method causes a physical contradiction.

 The present invention has been made in view of the above points, and intends to propose an image display device and a driving method of the image display device that can significantly improve the prediction accuracy of the degradation of the light emission luminance as compared with the conventional art. To do.

  In order to solve the above problems, the invention of claim 1 is applied to an image display device, and an image display panel that displays image data by a self-luminous element, a light receiving element that receives light emitted from the image display panel, A luminance correction unit that processes a light reception result of the light receiving element and corrects a gradation of image data displayed on the image display panel; The brightness correction unit includes a master deterioration curve generation unit that generates a master deterioration curve that indicates a temporal change in light emission luminance of the self-light-emitting element based on the light reception result, and the self-light emission at a gradation corresponding to the image data. A cumulative amount calculation unit that detects the cumulative amount of deterioration by accumulating the amount of deterioration when the element is driven for a unit time, and a correction amount determination unit that sets the correction amount of the image data based on the cumulative amount of deterioration And have. The deterioration amount when the self-luminous element is driven for a unit time is a deterioration amount converted into a display time on the master deterioration curve, and the correction amount determination unit is a display time deterioration corresponding to the cumulative deterioration amount. The correction amount is determined by detecting the amount from the master deterioration curve.

  The invention of claim 7 is applied to a driving method of an image display device having an image display panel for displaying image data by a self-light emitting element and a light receiving element for receiving light emitted from the image display panel. A luminance correction step of processing a light reception result of the light receiving element and correcting a gradation of image data displayed on the image display unit; The brightness correction step includes a master deterioration curve generation step for generating a master deterioration curve indicating a temporal change in light emission luminance of the self-light-emitting element based on the light reception result, and the self-light emission at a gradation corresponding to the image data. A cumulative deterioration amount calculating step for detecting a cumulative deterioration amount by accumulating the deterioration amount when the element is driven for a unit time; and a correction amount determining step for setting a correction amount of the image data based on the cumulative deterioration amount And have. The deterioration amount when the self-luminous element is driven for a unit time is a deterioration amount converted into a display time on the master deterioration curve, and the correction amount determining step includes a display time deterioration corresponding to the cumulative deterioration amount. The correction amount is determined by detecting the amount from the master deterioration curve.

  According to the configuration of claim 1 or claim 7, the deterioration amount converted into the display time on the master deterioration curve is accumulated, and the deterioration amount of the corresponding display time is detected from the master deterioration curve, whereby the master deterioration curve is obtained. Even when the light emission brightness due to the value approaches 0 due to an increase in time, it is possible to prevent the occurrence of physical contradiction in which the light emission brightness at a higher gray level becomes 0 or less. In addition, regardless of the amount of deterioration of each pixel, the amount of deterioration is predicted on the master deterioration curve. Therefore, when the deterioration amounts become equal at a predetermined time and there are organic EL elements that are driven at the same gradation, it is possible to ensure that the deterioration amounts of these organic EL elements are equal. Therefore, a physical contradiction due to the conventional method can be effectively avoided, and the prediction accuracy of the degradation of the light emission luminance can be remarkably improved as compared with the conventional case.

  According to the present invention, it is possible to significantly improve the prediction accuracy of the degradation of light emission luminance as compared with the conventional case.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. The description will be given in the following order.
1. First Embodiment 2. FIG. Second Embodiment 3. FIG. Third embodiment 4. Modification <First Embodiment>
[Configuration of the embodiment]
FIG. 2 is a diagram illustrating the image display apparatus according to the first embodiment of the present invention. The image display device 1 displays a desired image by driving the image display panel 3 with image data D1 input via the luminance correction unit 2.

  Here, in the image display panel 3, the pixel circuits 5 are arranged in a matrix to form the image display unit 4 that is an effective pixel region. The pixel circuit 5 is formed by an organic EL element 6 that is a self-luminous element and a drive circuit that drives the organic EL element 6. Further, in the image display panel 3, a dummy pixel circuit 5D is provided in a portion other than the image display unit 4, and a dummy organic EL element 6D is provided by the dummy pixel circuit 5D.

  Here, as shown in FIG. 2B, a cross section taken along the line AA, the dummy organic EL element 6 </ b> D is formed so as to emit outgoing light to the back side of the image display panel 3. More specifically, in the image display panel 3, the organic EL element 6 of the image display unit 4 is created by the top emission method, while the dummy organic EL element 6D is created by the bottom emission method. The dummy pixel circuit 5D is created in the same manner as the pixel circuit 5 of the image display unit 4 except that the organic EL element 6D is created by the bottom emission method. In FIG. 2, reference numerals L1 and L1D denote the emitted light from the organic EL elements 6 and 6D.

  In the image display panel 3, a light receiving element 7 that receives the emitted light L <b> 1 </ b> D of the dummy organic EL element 6 </ b> D is disposed on the back side of the image display panel 3. The light receiving element 7 is a photodiode, for example, and is arranged by bonding using a transparent adhesive, for example. In the image display device 1, the dummy organic EL element 6 </ b> D is driven by the luminance correction unit 2, and the light emission luminance of the organic EL element 6 </ b> D is measured at a constant time interval based on the light reception result of the light receiving element 7. Further, based on the measured light emission luminance, the luminance correction unit 2 corrects the gradation of the image data D1 and outputs it to the image display panel 3 to correct the decrease in the light emission luminance.

[Detailed configuration of brightness correction unit]
FIG. 1 is a block diagram showing a detailed configuration of the luminance correction unit 2. Note that the luminance correction unit 2 includes, for example, arithmetic processing means for executing a luminance correction program and peripheral circuits of the arithmetic processing means. Therefore, each block of the luminance correction unit 2 shown in FIG. 1 is a functional block configured by the arithmetic processing means and the peripheral configuration of the arithmetic processing means.

  The correction unit 11 multiplies the image data D1 by the correction amount for each pixel determined by the correction amount determination unit 12, and corrects the gradation of the image data D1 to generate image data D3. The correction unit 11 time division multiplexes the image data D3 and the drive data D2 output from the dummy pixel control unit 13 and outputs the result to the image display panel 3.

  The image display panel 3 drives the pixel circuit 5 of the image display unit 4 with the image data D3. Further, the drive data D2 is input to the dummy pixel circuit 5D, and the dummy organic EL element 6D is caused to emit light by the drive data D2. Instead of the image data D3 and the drive data D2 being time-division multiplexed and input to the image display panel 3, the image data D3 and the drive data D2 may be individually input to the image display panel 3.

  The degradation amount calculation unit 14 searches the gradation / degradation amount table 15 with the image data D3 output from the correction unit 11, and detects and outputs the degradation amount corresponding to the gradation of the image data D3. Here, the gradation / deterioration amount table 15 is a table in which the deterioration amount when the organic EL element is driven in unit time for each gradation is converted into a display time on the master deterioration curve and recorded. In this embodiment, this unit time is set to a period of one frame which is a repetition cycle of the image data D1.

  The cumulative degradation amount calculation unit 16 adds the degradation amount per unit time detected by the degradation amount calculation unit 14 to the cumulative degradation amount of the corresponding pixel recorded in the cumulative degradation amount accumulation unit 17 and outputs the result. The cumulative deterioration amount accumulation unit 17 records and holds the deterioration amount calculated by the cumulative deterioration amount calculation unit 16 for each pixel.

  The correction amount determination unit 12 calculates the correction value of the corresponding image data D1 based on the deterioration amount for each pixel recorded in the cumulative deterioration amount accumulation unit 17.

  Accordingly, the luminance correction unit 2 detects the deterioration amount of each pixel by accumulating the corresponding gradation deterioration amount recorded in the gradation / degradation amount table 15 for each pixel of the image display unit 4. The gradation of each pixel is corrected based on the amount. The luminance correction unit 2 generates a master deterioration curve, which is a correction reference for each pixel, from the light reception result of the light receiving element 7. Further, the luminance correction unit 2 updates the record of the gradation / deterioration amount table 15 at a constant update cycle in accordance with a deterioration rate conversion function described later. Here, this update cycle is set to a period of a plurality of frames.

  That is, in the brightness correction unit 2, the deterioration amount measurement unit 18 processes the light reception result of the light receiving element 7 to detect the light emission brightness of the dummy pixel, and outputs this detection result.

  The dummy pixel control unit 13 generates and outputs drive data D2 by feedback control based on the detection result of the deterioration amount actual measurement unit 18, and causes the organic EL element 6D to emit light with a constant light emission luminance. In this embodiment, the constant light emission luminance is the light emission luminance corresponding to the maximum gradation of the image data D3. In addition, the dummy pixel control unit 13 stops the feedback control at the update cycle and outputs drive data D2 for light emission luminance measurement.

  The master deterioration curve generation unit 20 records and holds the light emission luminance of the organic EL element 6D detected in this update cycle, and generates a master deterioration curve. Therefore, in this embodiment, the master deterioration curve is a characteristic curve showing the temporal change in the emission luminance of the dummy organic EL element 6D. In addition, the master deterioration curve generation unit 20 updates the gradation / deterioration amount table 15 at this update cycle in accordance with a deterioration rate conversion function described later.

[Prediction principle of deterioration amount]
Here, the deterioration amount when the organic EL element is driven at the gradations L and Lo is proportional to the deterioration rate conversion function g (L, Lo) as shown in the equation (1) and FIG. Therefore, if the inverse function related to the time t of the deterioration curve f (t, L) is set to f ⁻¹ (y, L) and the time required for deterioration of the unit deterioration amount is compared between the gradations Lo and L, the relationship of the following equation is obtained. The formula can be obtained.

  Here, the denominator on the left side of equation (2) indicates the time required for deterioration of the unit deterioration amount in the gradation L, and the denominator on the right side of equation (2) is required for deterioration of the unit deterioration amount in the gradation Lo. Will show the time. Therefore, equation (2) can be rewritten as shown in the following equation.

  The function g (L, Lo) described above is a function indicating the gradation dependence of the deterioration rate, whereas the function 1 / g (L, Lo) in the equation (3) is a unit deterioration amount. This is a function indicating the gradation dependency of the time required for deterioration. Therefore, the deterioration curve y = f (t, L) of the gradation L can be expressed by the following equation. As shown in FIG. 3, the master deterioration curve f (t, L) is equivalent to the function g (L, Lo). Lo) It can be seen that it is expanded and contracted in the time axis direction.

  In this embodiment, by utilizing the relationship of the equation (4), the amount of deterioration when the organic EL element is driven at unit time for each gradation is converted into the display time on the master deterioration curve, and each organic EL element is converted. 6 is detected.

[Prediction of deterioration amount by master deterioration curve]
Here, from equation (4), when the organic EL element is driven at the predetermined gradation L for the time t, the organic EL element is driven at the master deterioration curve gradation Lo for the time t / g (L, Lo). It becomes equal to the deterioration amount in the case of.

  On the other hand, the organic EL element 6 provided in the image display unit 4 emits light at various light emission luminances for various times according to the image data D1. Here, it is assumed that the desired organic EL element emits light for the time t (i) at the gradation L (i). As shown by the following equation, the deterioration amount at this time is that the organic EL element emits light at the gradation of the master deterioration curve for the time obtained by dividing the light emission time t (i) by the function g (L (i), Lo). It is equal to the case.

  In this case, the emission luminance y is expressed by the following equation.

  Therefore, in this embodiment, the calculation processing of equation (5) is executed based on the recording of the gradation / degradation amount table 15 to detect the deterioration amount of each organic EL element.

[Deterioration function]
In this embodiment, the function g (L, Lo) is defined by the following equation on the assumption that the deterioration rate increases in proportion to the gradation. Therefore, in this case, if the light emission luminance of the organic EL element is increased by n times, the deterioration rate is also increased by n times, and the time required for deterioration of the unit deterioration amount is reduced by 1 / n times. Therefore, in this case, the gradation / degradation amount conversion table 15 can be easily set.

  Since there is a case where the deterioration rate changes at an acceleration with respect to the luminance variation, the function g (L, Lo) may be defined by the following equation using the time acceleration coefficient α. In this case, the deterioration amount can be obtained with a small amount of information by a relatively simple calculation.

  Alternatively, the time acceleration coefficient α may be changed at the gradation L as shown by the following equation. In this case, even if the time acceleration coefficient α has gradation dependency, the deterioration amount can be obtained with high accuracy. In this case, the time acceleration coefficient α (L) is set so that the value continuously changes with respect to the change in the gradation L, so that the change in the correction amount obtained from the master deterioration curve does not become discontinuous. To.

  Alternatively, as shown by the following equation, the time acceleration coefficient α may be changed by the luminance deterioration amount. Note that the luminance deterioration amount detected from the dummy organic EL element can be applied to the luminance deterioration amount. In this case, even if the time acceleration coefficient α is dependent on the luminance deterioration amount, the deterioration amount can be obtained with high accuracy. In this case as well, the time acceleration coefficient α (luminance deterioration amount) is set so that the value continuously changes with respect to the change in luminance deterioration amount so that the change in correction amount does not become discontinuous.

  Instead of these, as shown by the following equation, the acceleration coefficient α may be changed by the gradation L and the luminance deterioration amount.

[Specific prediction of deterioration amount]
Based on the above-described degradation amount prediction principle, in the luminance correction unit 2, the gradation / degradation amount conversion table 15 records and holds the value of the function 1 / g (L, Lo) for each gradation L. As shown in FIG. 4, the master deterioration curve generation unit 20 acquires and records the emission luminance y of the dummy organic EL element 6D detected for each update period, so that the master deterioration curve y = f (t, A sampling value of Lo) is acquired and a master deterioration curve is generated. Further, when the speed deterioration conversion function g (L, Lo) is defined by the arithmetic processing of the equation (10) or (11), the master deterioration curve generation unit 20 uses the light reception result detected by the deterioration amount actual measurement unit 18 as a result. Based on this, the gradation / degradation amount conversion table 15 is updated every update period.

  The deterioration amount calculation unit 14 searches the gradation / deterioration amount conversion table 15 to detect the right side of the equation (5), t (i) / g (L (i), Lo), and the accumulated deterioration amount calculation unit 16. Performs the arithmetic processing of equation (5). As shown in FIG. 4, the correction amount determination unit 12 determines the master deterioration based on the display time t (Σ {t (i) / g (L (i), Lo)}) obtained by the cumulative deterioration amount calculation unit 16. A deterioration amount Δy on the curve is detected, and a correction amount of the corresponding image data is determined.

[Operation of the embodiment]
In the above configuration, in the image display device 1 (FIG. 2), sequentially input image data D1 is input to the image display panel 3 via the luminance correction unit 2. In the image display panel 3, the light emission luminance of each organic EL element 6 constituting the image display unit 4 is set by the image data D3 input through the luminance correction unit 2, thereby displaying an image based on the image data D3. To do.

  However, the higher the emission luminance of the organic EL element 6 is, the lower the luminous efficiency is as it is used for a long time. As a result, in the image display device 1, a decrease in light emission luminance, a change in chromaticity, and burn-in occur.

  Therefore, in the image display device 1, dummy organic EL elements 6 </ b> D and light receiving elements 7 are provided in parts other than the image display unit 4 of the image display panel 3, and the light emission luminance of the organic EL elements 6 provided in the image display panel 3. Is monitored by the luminance correction unit 2. Further, the gradation of the image data D3 used for driving each organic EL element 6 is corrected by the luminance correction unit 2 based on the monitoring result, thereby preventing a decrease in emission luminance, a change in chromaticity, and a burn-in.

  More specifically, in the image display device 1, the dummy organic EL element 6D is caused to emit light with a constant light emission luminance, and the light emission luminance of the organic EL element 6D at a predetermined gradation is detected at a constant update period. As a result, the image display apparatus 1 detects a master deterioration curve y = f (t, Lo) that is a reference for gradation correction. In the image display device 1, the deterioration amount of each organic EL element 6 is detected based on the master deterioration curve y = f (t, Lo). In the image display device 1, the gradation of the image data D1 is corrected so as to correct the deterioration amount of each organic EL element 6, and as a result, a decrease in light emission luminance, a change in chromaticity, and a burn-in are prevented.

  However, according to the conventional method (the method disclosed in Japanese Patent Application Laid-Open No. 2007-156044), the deterioration amount due to the master deterioration curve y = f (t, Lo) is simply multiplied by the deterioration rate conversion function g (L, Lo). If the amount of deterioration is obtained, various inconveniences occur (see equation (1), FIG. 6).

  That is, when estimating the deterioration of the light emission luminance at each gradation using the relationship of the equation (1), the master deterioration curve y = f (t, Lo) is set to the vertical axis by the deterioration rate conversion function g (L, Lo). The deterioration curve y = f (t, L) of the gradation L is obtained by expanding and contracting in the direction. Therefore, when the emission luminance y due to the master deterioration curve y = f (t, Lo) approaches the value 0 due to the increase in time t, the deterioration curve y = f (t, L) at the gradation L larger than the gradation Lo becomes The value may be 0 or less. Therefore, in the conventional method, a physical contradiction occurs.

  In the case of the conventional method, the deterioration amount is predicted by selecting the deterioration curve based on the change in gradation of the organic EL element provided in the image display unit. Therefore, the amount of deterioration happens to be equal at a predetermined point in time, and even if there are organic EL elements that are driven at the same gradation, it may not be possible to ensure that the amount of deterioration of these organic EL elements is equal. To do. Also in this case, the conventional method causes a physical contradiction.

  As a result, in the conventional method, there is a problem that is not practically sufficient in predicting the deterioration of the light emission luminance in each organic EL element 6, and the image quality deterioration cannot be corrected accurately.

  Therefore, in the image display device 1, degradation when the organic EL element is driven for each gradation for each unit time using the degradation function 1 / g (L, Lo) indicating the gradation dependency of the time required for degradation of the unit degradation amount. The gradation / degradation amount conversion table 15 is created by converting the amount into the display time on the master deterioration curve. Further, at a certain time interval, the dummy organic EL element 6D is driven by the maximum gradation with the fastest deterioration speed, and the master deterioration curve y = f (t, Lo) is obtained. Further, the gradation / deterioration amount table 15 is searched from the image data D3, the deterioration amounts are integrated for each pixel, and the deterioration amount of each pixel converted into the display time of the master deterioration curve y = f (t, Lo) is Accumulated for each pixel. Also, from this cumulative result, the amount of deterioration is obtained from the master deterioration curve (FIG. 4), and the gradation of each pixel is corrected so as to correct this amount of deterioration, thereby reducing the emission luminance, variation in chromaticity, Prevent seizure.

  In this case, in the image display apparatus 1, the master deterioration curve y = f (t, Lo) is expanded and contracted in the time axis direction to obtain the deterioration curve y = f (t, L) for each gradation. Therefore, even if the light emission luminance y approaches 0 as the time t increases, the light emission luminance y according to the deterioration curve y = f (t, L) can be set so as not to fall below the value 0. Therefore, the physical contradiction in the conventional method can be effectively avoided, and as a result, the deterioration amount can be predicted with high accuracy.

  In addition, regardless of the amount of deterioration of each pixel, the amount of deterioration is predicted on the master deterioration curve. Therefore, when the deterioration amounts become equal at a predetermined time and there are organic EL elements that are driven at the same gradation, it is possible to ensure that the deterioration amounts of these organic EL elements are equal. Accordingly, it is possible to effectively avoid a physical contradiction in the conventional method, and as a result, it is possible to predict the deterioration amount with high accuracy.

  As a result, the image display device 1 can improve the degradation prediction accuracy of the light emission luminance in each organic EL element 6 as compared with the prior art, and reliably prevent the light emission luminance from decreasing, chromaticity variation, and burn-in. be able to.

[Effect of the embodiment]
According to the above configuration, by detecting the amount of deterioration of each pixel based on the amount of deterioration converted to the display time on the master deterioration curve and correcting the light emission luminance, the prediction accuracy of the light emission luminance deterioration is improved compared to the conventional case. It can be remarkably improved.

  More specifically, by creating a master deterioration curve with dummy self-light-emitting elements, specifically, the prediction accuracy of the deterioration of the light emission luminance can be significantly improved as compared with the conventional case.

  In addition, for each gradation of image data, a table is provided that records the deterioration amount when the self-luminous element is driven for a unit time, and the table is obtained by accumulating the search results of this table and detecting the deterioration amount of each pixel. With the simple processing used, it is possible to significantly improve the prediction accuracy of the deterioration of the light emission luminance as compared with the conventional case.

  Further, by updating this table based on the light reception result of the light receiving element at a predetermined timing, it is possible to further improve the prediction accuracy of the deterioration of the light emission luminance.

  In addition, since the self-luminous element is an organic EL element, it can be applied to a flat display device using the organic EL element to prevent luminance deterioration, chromaticity change, and burn-in.

  Further, by emitting emitted light from the self-light emitting element of the dummy pixel to the back side of the image display panel, the configuration of the housing that holds the image display panel can be simplified.

<Second Embodiment>
FIG. 5 is a block diagram showing an image display apparatus according to the second embodiment of the present invention. In this image display device 21, the same configuration as that of the image display device 1 of the first embodiment is denoted by the corresponding reference numeral, and redundant description is omitted.

  The image display device of this embodiment drives the dummy organic EL element 6D with a predetermined gradation other than the highest gradation of the image data D3. The image display apparatus according to this embodiment is configured in the same manner as in the first embodiment except that the configuration relating to the gradation related to the driving of the dummy organic EL element 6D is different.

  Here, this gradation may be a fixed gradation or variously variable. In the case of a fixed gradation, for example, an intermediate gradation or the lowest gradation can be applied. If the dummy organic EL element is driven with a fixed gradation, the system configuration can be simplified.

  On the other hand, when changing the gradation, for example, the gradation may be periodically changed according to a certain pattern, or the gradation may be changed randomly, thereby changing the gradation regardless of the image data D3. . In this case, since the master deterioration curve can be measured in a state close to the actual image display state, the deterioration curve can be predicted with high accuracy. Further, when changing the gradation, the gradation of the dummy pixel is set by the average gradation of the image data D3, the gradation of the specific pixel of the image display unit, and the like, and the level of the dummy organic EL element 6D is set according to the image data D3. The key may be variable. In this case, since the gradation of the dummy organic EL element 6D can be set according to the image data actually displayed, the deterioration curve can be predicted with high accuracy. Needless to say, when the gradation of the dummy organic EL element is varied, it is necessary to update the contents of the gradation / degradation amount conversion table accordingly.

  However, when the dummy organic EL element 6D is driven at a gradation lower than the maximum gradation of the image data D3 as described above, a master deterioration curve cannot be generated from the measurement result of the dummy pixel for the future from the present time. As a result, depending on the method of the first embodiment, it is not possible to detect the amount of deterioration on the master deterioration curve for a pixel whose deterioration speed is faster than the master deterioration curve.

  Therefore, in this embodiment, the master deterioration curve generation unit 30 records a master curve indicating a temporal change in emission luminance when the organic EL element corresponding to the dummy organic EL element 6D emits light at a constant gradation. Hold. In the case where the dummy organic EL element 6D is displayed with a fixed gradation, it is desirable that the gradation of the master curve is equal to the fixed gradation, but even if these gradations are set differently. Good. The master deterioration curve generation unit 30 generates a master deterioration curve up to the current time point based on the light emission luminance of the dummy organic EL element 6D detected in the update cycle. The master deterioration curve generation unit 30 corrects the master curve and generates a master deterioration curve after the current time point.

  Specifically, as shown by the following formula, the master deterioration curve generation unit 30 multiplies the master curve luminance value F (t, Lo) by a predetermined ratio to obtain a master deterioration curve f (t, Lo) after the current time point. ) Is generated. Here, this ratio is a ratio between the luminance value F (To, Lo) of the master curve and the luminance value f (To, Lo) of the master deterioration curve at the current time To.

  Instead, as shown by the following equation, the deterioration amount of the master curve at the current time To (1-f (To, Lo)) and the deterioration amount of the master deterioration curve (1-F (To, Lo)) The master deterioration curve f (t, Lo) after the current time point may be generated by multiplying the deterioration amount (1-F (t, Lo)) of the master curve by the ratio.

  Alternatively, as shown by the following equation, a master deterioration curve after the current time point may be generated by adding a predetermined value to the luminance value F (t, Lo) of the master curve. Here, the predetermined value is a difference value (f (To, Lo) −F (To, Lo)) of luminance values at the current time To.

  Instead of this, as shown by the following equation, the difference value ((1−f (To, Lo)) − (1−F (To, Lo))) of the deterioration amount at the current time To is added to obtain the master. A deterioration curve f (t, Lo) may be generated.

  According to this embodiment, it is possible to predict the deterioration amount of the emission luminance with higher accuracy by generating the master deterioration curve by setting the gradations of the dummy pixels in various ways.

  In addition, by generating a master deterioration curve after the current time using the master curve, it is possible to maintain the continuity of the master deterioration curve and accurately predict the amount of deterioration of the light emission luminance even for pixels with a high deterioration rate. it can.

<Third Embodiment>
In the image display device of this embodiment, the light-emitting luminance of the organic EL element of the image display unit is detected instead of the organic EL element of the dummy pixel by the light receiving element arranged in the vicinity of the image display unit. The image display apparatus according to this embodiment is configured in the same manner as the first or second embodiment described above except that the configuration relating to the light receiving element is different.

  For this reason, the image display device switches the operation mode, for example, when the image display device is turned on, and displays a predetermined pattern for measuring the deterioration amount of the light emission luminance on the image display unit. A master deterioration curve is generated based on the light reception result of the predetermined pattern. In this case, when the gradation / degradation amount table is set by the deterioration rate conversion function having gradation dependency, the gradation / degradation amount table is updated together. In this case, the luminance can be detected stably at a specific gradation.

  Alternatively, a series of processes such as monitoring the gradation of the image data and detecting the emission luminance and generating a master deterioration curve when the image data has a specific gradation may be executed. Good.

  Alternatively, a series of data such as recording and holding data indicating the gradation dependence of the light emission luminance, correcting the light emission luminance detected via the light receiving element with this data, and generating a master deterioration curve, etc. Processing may be executed.

In this embodiment, it is possible to predict the deterioration of the light emission luminance with higher accuracy by detecting the light emission luminance of the image display unit instead of the dummy pixel.
<Modification>
In the first and second embodiments described above, the case where the organic EL element of the image display unit and the organic EL element of the dummy pixel are formed by the top emission method and the bottom emission method has been described. However, the present invention is not limited to this, and the organic EL element of the image display unit and the organic EL element of the dummy pixel may be created by the bottom emission method and the top emission method.

  If the configuration of the housing in which the image display panel is arranged can be simplified practically, for the dummy pixel organic EL element, both the upper and lower electrodes sandwiching the organic EL layer are made of transparent electrodes, The emitted light may be emitted to both the emission surface and the back surface. Moreover, you may produce both the organic EL element of an image display part, and the organic EL element of a dummy pixel by a top emission system or a bottom emission system.

  Furthermore, in the above-described embodiment, the case where the light receiving element is arranged on the back surface of the image display panel has been described. However, the present invention is not limited thereto, and may be arranged in the image display panel.

  In the first and second embodiments described above, the case has been described in which the deterioration amount is detected by searching the gradation / deterioration amount conversion table using the image data whose gradation has been corrected by the correction unit. However, the present invention is not limited to this, and the deterioration amount may be detected by searching the gradation / deterioration amount conversion table based on the image data before correcting the gradation by the correction unit. In this case, the emission luminance feedback control by the dummy pixel control unit 13 may be stopped so as to correspond to the detection of the deterioration amount by the image data before the gradation is corrected by the correction unit.

  In the above-described embodiment, the case where the correction value is set by accumulating the deterioration amount for each pixel has been described. However, the present invention is not limited to this, and may be widely applied to the case where the correction value is set by accumulating the deterioration amount for each of a plurality of pixels, or the case where the correction value is set in common for the entire screen of the image display panel. it can.

  Further, in the above-described embodiment, the case has been described in which the deterioration amount when the organic EL element is caused to emit light at all gradations is stored in the table. However, the present invention is not limited to this, and in the case where sufficient accuracy can be secured in practice, the deterioration amount is stored in a table for each of the plurality of gradations, and the deterioration amount of each pixel is used using the deterioration amount for each of the plurality of gradations. May be predicted.

  In the above-described embodiment, the case where the correction amount is set for each frame has been described. However, the present invention is not limited to this. For example, the correction amount may be set in units of a plurality of frames by searching the gradation / degradation amount conversion table using the average luminance of a plurality of frames.

  In the first and second embodiments described above, the case where the light emission luminance of all the pixels provided in the image display panel is corrected by the light reception result of one dummy pixel has been described. However, the present invention is not limited to this, and the present invention can be widely applied to a case where the image display panel is divided into predetermined regions and dummy pixels are provided for each region to correct the light emission luminance. Alternatively, the present invention can be widely applied to a case where a dummy pixel is provided for each color and the light emission luminance of each color is corrected by the light reception result of the corresponding dummy pixel.

  Further, in the above-described embodiment, the case where the image display panel is configured by the self-luminous element by the organic EL element has been described. However, the present invention is not limited to this, and the case where the image display panel is configured by various self-luminous elements. Can be widely applied.

  In the above-described embodiments, the configuration of a suitable image display device has been described. However, the present invention is not limited to this, and the image display device is configured by combining the configurations of the above-described embodiments as necessary. May be.

  The present invention can be applied to an active matrix image display device using a self-luminous element such as an organic EL (Electro Luminescence) element.

It is a block diagram which shows the detailed structure of the image display apparatus of the 1st Embodiment of this invention. It is a figure which shows the image display apparatus of the 1st Embodiment of this invention. It is a characteristic curve figure which shows the relationship between a master deterioration curve and a deterioration curve. It is a characteristic curve figure with which it uses for description of the detection of deterioration amount. It is a block diagram which shows the image display apparatus of the 2nd Embodiment of this invention. It is a characteristic curve figure with which it uses for description of the detection of the deterioration amount by a conventional method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,21 ... Image display apparatus, 2 ... Luminance correction part, 3 ... Image display panel, 6, 6D ... Organic EL element, 7 ... Light receiving element, 12 ... Correction amount determination part, 15 ... Floor Tone / deterioration amount conversion table, 16... Cumulative deterioration amount calculation unit

Claims (7)

An image display panel for displaying image data by a self-luminous element;
A light receiving element for receiving light emitted from the image display panel;
A brightness correction unit that processes a light reception result of the light receiving element and corrects a gradation of image data displayed on the image display panel;
The brightness correction unit
A master deterioration curve generation unit that generates a master deterioration curve indicating a temporal change in light emission luminance of the self-light-emitting element based on the light reception result;
A cumulative deterioration amount calculation unit that detects the cumulative deterioration amount by accumulating the deterioration amount when the self-light-emitting element is driven for a unit time at a gradation corresponding to the image data;
A correction amount determination unit that sets a correction amount of the image data based on the cumulative deterioration amount;
The amount of deterioration when the self-luminous element is driven for a unit time is the amount of deterioration converted into display time on the master deterioration curve,
The correction amount determination unit
An image display device that detects a deterioration amount of a display time corresponding to the cumulative deterioration amount from the master deterioration curve and determines the correction amount. The image display panel is
The self-light-emitting elements are arranged in a matrix to form an image display unit, and dummy self-light-emitting elements are arranged in parts other than the image display unit,
The light receiving element is
The image display device according to claim 1, wherein light emitted from the dummy self-light-emitting element is received and a light reception result is output. The cumulative deterioration amount calculation unit
For each gradation of the image data, a table that records the amount of deterioration when the self-luminous element is driven for a unit time,
A deterioration amount calculation unit that searches the table and detects a deterioration amount corresponding to the gradation of the image data;
The image display device according to claim 1, wherein the accumulated deterioration amount is detected by accumulating detection results of the deterioration amount calculation unit. The deterioration amount recorded in the table has gradation dependency,
The brightness correction unit
The image display apparatus according to claim 3, further comprising a table update unit that updates the table based on a light reception result of the light receiving element at a predetermined timing. The image display device according to claim 3, wherein the self-luminous element is an organic EL element. The dummy self-luminous element is
Emission light is emitted to the back side of the image display panel,
The image display device according to claim 3, wherein the light receiving element is disposed on a back side of the image display panel. An image display panel for displaying image data by a self-luminous element;
A method of driving an image display device having a light receiving element that receives light emitted from the image display panel,
A luminance correction step of processing a light reception result of the light receiving element and correcting a gradation of image data to be displayed on the image display unit;
The brightness correction step includes
Based on the light reception result, a master deterioration curve generation step for generating a master deterioration curve indicating a temporal change in light emission luminance of the self-light-emitting element;
A cumulative deterioration amount calculating step of accumulating the deterioration amount when the self-light-emitting element is driven for a unit time at a gradation corresponding to the image data and detecting the cumulative deterioration amount;
A correction amount determining step for setting a correction amount of the image data based on the cumulative deterioration amount;
The amount of deterioration when the self-luminous element is driven for a unit time is the amount of deterioration converted into display time on the master deterioration curve,
The correction amount determining step includes:
A method for driving an image display device, comprising: detecting a deterioration amount of a display time corresponding to the cumulative deterioration amount from the master deterioration curve and determining the correction amount.

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