JP2010102001A - Image display device and method for driving the image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve the deterioration in image quality due to defective pixels than in the conventional manner. <P>SOLUTION: The image display device has a display part in which pixels are arranged in a matrix form, and a drive part which drives the pixels arranged in the display part in accordance with image data, so as to display a desired image on the display part. The drive part has a luminance-adjusting part which partially adjusts the luminance of the defective pixel, having a low luminance region or a light non-emitting region. By setting integral luminance on the area of the defective pixels or the integrated luminance on the area of the defective pixels and the time by the luminance-adjusting part, the low emitted light luminance region or the light non-emitting region is made less apt to be viewed, in comparison with the case, where the luminance of the defective pixel is not adjusted by the luminance-adjusting part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image display device and a method for driving the image display device, and can be applied to an image display device using an organic EL (Electro Luminescence) element, for example. The present invention adjusts the luminance of a defective pixel partially having a low luminance region or a non-luminous region, and makes it difficult to visually recognize a low luminance region or a non-luminous region as compared with the case where the luminance of the defective pixel is not adjusted. As a result, image quality deterioration due to defective pixels is further improved as compared with the conventional case.

  In recent years, image display devices using organic EL elements have been actively developed. Here, as shown in FIG. 20, in this type of image display apparatus 11, the display unit 2 is formed by arranging pixels in a matrix. The image display device 1 drives the display unit by the drive circuit 3 in accordance with the sequentially input image data D1, and displays a desired image on the display unit 2.

  Image display devices using organic EL elements are roughly classified into a passive matrix type and an active matrix type. Here, as shown in FIG. 21, the passive matrix type image display device 5 includes pixels formed by organic EL elements OLED (1, 1), OLED (1, 2),. Is formed. The image display device 5 sequentially and cyclically selects the scanning lines SCAN (1), SCAN (2),... By the switch circuit 6 provided in the drive circuit 3. The image display device 5 distributes the sequentially input image data D1 to the current drive circuits 7 (1), 7 (2),..., And the current drive circuits 7 (1), 7 (2),. Drive currents Isig (1), Isig (2),... Corresponding to the data D1 are generated and output to the corresponding signal lines. Thus, the image display device 5 displays the desired image by sequentially emitting the organic EL elements OLED (1, 1), OLED (1, 2),. Thereby, the image display device 5 sets the gradation of each pixel by current driving via the signal line.

  As shown in FIG. 22, the active matrix type image display device 11 drives the organic EL element OLED and the organic EL element OLED constituting the pixels PIX (1,1), PIX (1,2),. The display unit 2 is formed by arranging the pixel circuits 16 including the driving circuits in a matrix. Here, the pixel circuit 16 includes, for example, both ends of a series circuit of a P-channel transistor Tr2 and the organic EL element OLED connected to the power sources Vdd and Vss, and the driving transistor Tr1 drives the organic EL element with a driving current according to the gate-source voltage. Drive the OLED. The pixel circuit 16 is provided with a holding capacitor Cs that holds the gate-source voltage of the driving transistor Tr1 between the gate and source of the driving transistor Tr1. In the pixel circuit 16, the terminal voltage of the storage capacitor Cs is sequentially set via the signal lines SIG (1), SIG (2),... Under the control of the writing transistor Tr3 via the scanning line SCAN. As a result, the pixel circuit 16 sets the gate-source voltage of the drive transistor Tr1 via the signal lines SIG (1), SIG (2),... To set the gradation of each pixel. The organic EL element OLED is current-driven with a driving current corresponding to the gate-source voltage.

  The drive circuit 3 distributes the sequentially input image data D1 to the respective signal lines SIG (1), SIG (2),..., And performs digital-analog conversion processing on the respective signal lines SIG (1), SIG (2). ,... Are set to drive voltages Vsig (1), Vsig (2),. Further, the drive circuit 3 controls the write transistor Tr3 on the scanning lines SCAN (1), SCAN (2),... Corresponding to the setting of the drive voltages Vsig (1), Vsig (2),. Is output.

  In addition, the image display device using the organic EL element can change the drive current of the organic EL element shown in FIG. 20 and FIG. 21 to express the gradation, and can also change the light emission time of the organic EL element to change the gradation. There are proposed a method (time modulation method) for expressing the tone, a method (area modulation method) for expressing gradation by changing the light emitting area of the organic EL element, and the like.

  Regarding an active matrix type image display device using an organic EL element, Japanese Patent Application Laid-Open No. 2007-310311 discloses a method of forming a pixel circuit using two transistors. Therefore, according to the method disclosed in Japanese Patent Application Laid-Open No. 2007-310311, the configuration can be simplified. Japanese Patent Laid-Open No. 2007-310311 discloses a configuration for correcting variations in threshold voltage and mobility in driving transistors that drive organic EL elements. Therefore, according to the configuration disclosed in Japanese Patent Application Laid-Open No. 2007-310311, it is possible to prevent image quality deterioration due to variations in threshold voltage and mobility in driving transistors.

  Japanese Patent Application Laid-Open Nos. 2000-195677 and 2003-178871 propose methods for repairing defective pixels by laser beam irradiation. Japanese Patent Laid-Open No. 2001-117534 proposes a method of repairing defective pixels by applying a reverse bias.

  That is, in an image display device using an organic EL element, defective pixels such as non-luminous pixels that do not emit light, low-luminance pixels with extremely low emission luminance, and high-luminance pixels that are observed as bright spots are generated due to various factors.

  Specifically, as shown in FIG. 23A, an organic EL element OLED applied to this type of image display device sandwiches an organic EL layer between a cathode and an anode held so as to face each other at a minute interval. The minute interval is set to 10 [μm] to several [μm]. In the organic EL element OLED, the upper electrode and the lower electrode are set as the cathode and the anode, respectively, and the lower electrode and the upper electrode are set as the cathode and the anode, respectively, depending on the configuration of the image display device. May be.

  Therefore, as shown in FIGS. 23B1 and 23C1, in the organic EL element OLED, the cathode and the anode may be short-circuited in the pixel in which the minute dust is mixed due to the mixing of the minute dust. Note that FIG. 23B1 illustrates a case where conductive dust is mixed between the electrodes and the cathode and the anode are short-circuited. FIG. 23C1 shows a case where the distance between the cathode and the anode is narrowed by dust mixed on the upper electrode, and the cathode and the anode are short-circuited. In this case, the pixel is a non-light emitting pixel. In addition, in the organic EL element, a leak current may be locally generated due to minute dust. In this case, the pixel is a low luminance pixel.

  In the organic EL element, a voltage of about several [V] to 10 [V] is applied between the cathode and the anode. Therefore, the organic EL element is locally short-circuited due to dielectric breakdown due to local electric field concentration due to variations in film thickness and film quality of the organic EL layer. In this case, the pixel is a non-light-emitting pixel. In some cases, the pixel is locally non-conductive. In this case, the pixel is a low-luminance pixel having a non-light-emitting region locally.

  In addition, in the organic EL element, the film quality of the organic EL layer and the structure of the organic EL layer material locally fluctuate due to the influence of impurities such as moisture, and as a result, the luminous efficiency of the organic EL element may fluctuate locally. is there. In this case, the pixel becomes a low-luminance pixel or a high-luminance pixel due to the variation in the light emission efficiency.

  These defective pixels are visually recognized as defects such as dark spots and bright spots in the image display device, and the image quality is significantly deteriorated. In particular, in a low-luminance region where the emission luminance is low, when the proportion of defective pixels increases, dark spots and bright spots become more conspicuous, and the image quality deteriorates significantly.

As shown in FIGS. 23B2 and 23C2, the technique disclosed in Japanese Patent Application Laid-Open No. 2000-195567 and the like locally removes an electrode in a defective pixel that causes a defective pixel. The remaining part is to function normally.
JP 2007-310311 A JP 2000-195567 A Japanese Patent Laid-Open No. 2003-177881 JP 2001-117534 A

  By the way, in the repair by the method disclosed in Japanese Patent Application Laid-Open No. 2000-195677 or the like, a portion where the electrode is locally removed becomes a non-light emitting region, and the pixel becomes a defective pixel having a local non-light emitting region. As a result, in these repairs, although the image quality can be improved as compared with the case where repair is not performed, there is still a problem that defects due to dark spots are still visually recognized. In particular, in the defective pixel, when the area of the non-light emitting region is increased, the defect becomes conspicuous, and there is a problem that the image quality is hardly improved even after repair.

  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 further improve image quality degradation due to defective pixels as compared with the conventional art. .

  In order to solve the above-mentioned problems, the invention of claim 1 is applied to an image display device to drive a display unit in which pixels are arranged in a matrix and a pixel arranged in the display unit according to image data, The display unit includes a drive unit that displays a desired image. The driving unit includes a luminance adjusting unit that adjusts the luminance of a defective pixel partially having a low luminance region or a non-light emitting region, and the luminance adjusting unit allows the integrated luminance depending on the area of the defective pixel, or the defect The integrated luminance depending on the area and time of the pixel is set so that the low luminance region or the non-luminous region is less visible as compared with the case where the luminance adjustment unit does not adjust the luminance of the defective pixel.

  The invention of claim 11 includes a display unit in which pixels are arranged in a matrix shape, and a drive unit that drives the pixels arranged in the display unit according to image data and displays a desired image on the display unit. This is applied to the driving method of the image display device. The integrated luminance depending on the area of the defective pixel partially having a low luminance area or a non-light emitting area, or the integrated luminance depending on the area and time of the defective pixel is adjusted, and the luminance adjustment unit does not adjust the luminance of the defective pixel. A step of adjusting the light emission luminance that makes it difficult to visually recognize the low light emission region or the non-light emission region as compared with the case is provided.

  According to the structure of claim 1 or claim 11, the integrated luminance depending on the area of a defective pixel partially having a low luminance region or a non-light emitting region, or the integrated luminance depending on the area and time of the defective pixel is adjusted. As compared with the case where the luminance adjustment unit does not adjust the luminance of the defective pixel, it is difficult to visually recognize the low light emission luminance region or the non-light emission region, thereby deteriorating image quality due to defective pixels such as defective pixels and repair pixels. This can be further improved as compared with the prior art.

  According to the present invention, it is possible to further improve image quality degradation due to defective pixels as compared with the conventional art.

  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. 1. First embodiment 2. Second embodiment 3. Third embodiment 4. Fourth embodiment 5. Fifth embodiment 6. Sixth embodiment 7. Seventh embodiment Modification <First Embodiment>
FIG. 1 is a block diagram showing an image display apparatus according to the first embodiment of the present invention in comparison with FIG. In the image display device 21, defective pixels of the display unit 2 are detected in the manufacturing process, and the defective pixels are repaired by irradiation with a laser beam, application of a reverse bias, or the like. Hereinafter, a defective pixel in which a non-light-emitting region is locally generated by repair is referred to as a repair pixel.

  The image display device 21 stores and holds information on the address and brightness adjustment amount, which is the position information of the repair pixel, in the pixel brightness adjustment information unit 22 configured by a memory. The image display device 21 corrects the light emission luminance of the repaired pixel by the luminance adjustment calculation circuit 23 provided in the drive circuit 3 based on the information stored in the pixel luminance adjustment information unit 22.

  More specifically, the image display device 21 corrects the light emission luminance of the repaired pixel by multiplying the image data D1 corresponding to the address stored in the pixel luminance adjustment information unit 22 by the luminance adjustment amount. The image display device 21 executes the correction of the light emission luminance of the repair pixel in consideration of the size of the non-light emitting area in the repair pixel. Note that the configuration of FIG. 22 is applied to the display unit 2. Therefore, the image display device 11 sets the voltage between the terminals of the storage capacitor Cs according to the image data D1 (FIG. 22), and drives the organic EL element OLED with a constant current according to the voltage between the terminals.

[Changes in emission luminance due to repair in constant current drive]
Here, as shown in FIG. 2, when the area of the light emitting region of the normal pixel is 1, the area ratio that is the area of the non-light emitting region in the repair pixel is α. Further, it is assumed that the non-light emitting region of the repair pixel is non-conductive between the electrodes and is completely non-light emitting, and the remaining region of the repair pixel emits light normally in the same manner as the normal pixel.

  In this case, the light emission luminance Loled of the organic EL element OLED can be expressed by the following equation. Here, Ioled is a drive current of the organic EL element OLED. Β is the amplification factor of the drive transistor Tr1, and Vth is the threshold voltage of the drive transistor Tr1. Vds is a drain-source voltage of the driving transistor.

  Note that λ is a constant. When the characteristics of the drive transistor Tr1 do not change with the drain-source voltage in the saturation region, λ = 0. However, since the characteristics of an actual transistor change depending on the drain-source voltage in the saturation region, λ> 0.

  The area of the light emitting region of the repair pixel is lower than that of the normal pixel due to the non-light emitting region. As a result, assuming that the current per unit area in the light emitting region is constant, in the repair pixel, the drive current is reduced by (1−α) times compared to the normal pixel. Accordingly, when the organic EL element OLED is driven with the same drive current as that of a normal pixel in current driving, the voltage V between the terminals of the organic EL element OLED increases by a voltage ΔVoled as shown in FIG. In FIG. 3, the horizontal axis represents the drain-source voltage.

  Here, the drive current Ioled1 of the normal pixel is expressed by the following equation.

  In the repair pixel, as shown in FIG. 4 in comparison with FIG. 3, the drain-source voltage Vds is reduced by a predetermined voltage ΔVds, and the drive current Ioled2 is expressed by the following equation.

  As a result, in the repair pixel, the light emission luminance per unit area in the light emission region increases, but the light emission luminance integrated with the area decreases. In the following, luminance integrated by area is simply referred to as integrated luminance by area. Here, when Ioled1 = Ioled2, the equations (2) and (3) can be rearranged to obtain the following equation.

  Accordingly, if the relational expression (4) is set to be satisfied, the integrated luminance based on the area can be made equal between the repair pixel and the normal pixel.

  As a result, as shown in FIG. 5, if the driving voltage Vsig is corrected by the area ratio α of the non-light emitting region in consideration of the characteristics of the driving transistor Tr1, the normal luminance and the repair pixel have the same integrated luminance depending on the area. It can be seen that it can be set to.

  In the case where the organic EL element is driven by the current driving circuit as shown in FIG. 21 and the current driving circuit has a sufficiently constant current characteristic, the repair pixel and the normal state are not corrected without any correction. The integrated luminance by area can be set to be the same for each pixel.

[Optimal brightness adjustment amount]
By the way, if the integrated luminance is simply set to be the same as that of a normal pixel, deterioration of the image quality may be perceived by the repair pixel.

  That is, as shown in FIG. 6, it is assumed that the area ratio α of the non-light emitting region in the repair pixel is 0.5. In the following, the light emission luminance of the unit area in the light emitting region is indicated by a number with a maximum value of 100. Here, when the light emission luminance per unit area of the normal pixel is 50, if the light emission luminance per unit area of the repair pixel is multiplied by 1 / (1-α), the integrated luminance due to the area between the normal pixel and the repair pixel is increased. The same can be set. Therefore, in this case, as shown in FIG. 6A, if the emission luminance per unit area of the repair pixel is set to 100, the integrated luminance due to the area can be set to be the same for the normal pixel and the repair pixel.

  In the example of FIG. 6A, when the human vision is recognizable by spatially resolving the non-light emitting area and the light emitting area in the repair pixel, similarly to the case where the human eye does not repair, The non-light emitting area and the light emitting area in the repair pixel are recognized as a dark spot and a bright spot, respectively.

  Therefore, simply setting the integrated luminance to be the same as that of the normal pixel may cause a perception of image quality degradation due to the repair pixel. Further, as shown in FIG. 21, when the organic EL element is driven by the current driving circuit, the current driving circuit has a sufficiently constant current characteristic, and the repair pixel and the normal pixel can be corrected without any correction. Even when the integrated luminance due to the area can be set to be the same, there is a risk that image quality degradation due to the repair pixel is perceived.

  In this case, as shown in FIG. 6 (B) by comparison with FIG. 6 (A), the emission luminance of the repair pixel is reduced as compared with the case where the integrated luminance by the area is the same as that of the normal pixel, By reducing the luminance difference between the recognized non-light-emitting area and the light-emitting area recognized as the bright spot, it is possible to make it difficult to perceive image quality degradation due to the repair pixel.

  In other words, in this case, it is possible to increase the integrated luminance due to the area of the repair pixel within a range equal to or lower than the integrated luminance due to the area of the normal pixel, thereby making it difficult to perceive image quality degradation. More specifically, as shown in FIG. 7, the light emission luminance per unit area of the repair pixel is set to the light emission luminance (FIG. 7A) in which the integral luminance of the repair pixel is set to be the same as that of the normal pixel. By setting the light emission luminance between the light emission luminance per unit area (FIG. 7B), it is possible to make the image quality degradation most difficult to perceive.

  That is, in this case, it is possible to make the image quality degradation most difficult to perceive by setting so as to satisfy the following relational expression. Here, L (unit area, normal pixel) and L (integration, normal pixel) are the emission luminance per unit area and the integrated luminance due to the area in the normal pixel, respectively. Further, L (unit area, repair pixel) and L (integration, repair pixel) are the emission luminance per unit area and the integrated luminance based on the area in the light emission region of the repair pixel, respectively.

  The equation (5) includes an equal sign. For human visual characteristics, if the pixel pitch is sufficiently high, or if the pixel pitch is significantly large, the integrated luminance by area or the unit area per normal pixel and repair pixel respectively. This is because it is possible to make it most difficult to perceive image quality degradation by setting the light emission luminances to the same.

  Here, the light emission luminance per unit area of the normal pixel and the integrated luminance due to the area are expressed as L (unit area, normal pixel) × 1 = L (integration, normal pixel), and the light emission luminance and area per unit area in the repair pixel. The integrated luminance by is expressed as L (unit area, repair pixel) × α = L (integration, repair pixel). In this case, equation (5) can be transformed into the following equation.

  Therefore, if the light emission luminance of the repair pixel is set so as to satisfy the relational expression (6), it is possible to repair the defective pixel and make it most difficult to perceive image quality degradation. In addition to the resolution and definition of the display unit, the optimum correction amount varies depending on the display brightness and the display image. Therefore, the luminance adjustment amount may be changed according to the gradation to be displayed according to the image to be displayed.

  Here, when the integrated luminance based on the area is set to be the same for the normal pixel and the repair pixel, the light emission luminance L (unit area, normal pixel) / (1-α) = light emission luminance L (unit area, repair pixel). What is necessary is just to set so that a relational expression may be satisfied. Therefore, equation (5) can also be expressed as shown in the following equation.

  Specifically, in this embodiment, as shown in FIG. 8A, the manufacturing process of the image display device 21 measures the light emission luminance of each pixel by emitting light at each intermediate gradation, and does not emit light. Detect defective pixels such as pixels, low-luminance pixels, and high-luminance pixels. In the example of FIG. 8A, the defective pixel is a non-light emitting pixel, and the light emission luminance per unit area is zero.

  In the manufacturing process, the defective part in the defective pixel is detected by detailed observation of the detected defective pixel, and repair processing is performed by irradiating this part with a laser beam or applying a reverse bias to the defective pixel. Execute. As a result, as shown in FIG. 8B, in the defective pixel, the electrode at the defective portion is destroyed. As a result, the defective pixel has a defective portion set as a non-light-emitting region, and the remaining region of the defective pixel is set as a light-emitting region, and becomes a defective pixel having a non-light-emitting region locally.

  Here, as shown in FIG. 8B, it is assumed that a non-light-emitting region having an area ratio α of 0.3 is generated by the repair process. Further, it is assumed that the light emission luminance per unit area in the light emission region has increased to 63. Even if the light emission luminance per unit area increases in this way, it is assumed that the repair pixel is still visually recognized as a dark spot on the image display device 21.

  Since α = 0.3, 50 ≦ L (unit area, repair pixel) ≦ 50 / (1-0.3) is obtained from the equation (7), and this is solved to obtain a unit area in the repair pixel. It can be seen that the optimum value of the hit emission luminance exists in the range of 50 to 71. Therefore, in this embodiment, for example, the drive signal Vsig for setting the light emission luminance of the repair pixel is determined so that the non-light emission region and the light emission region are most difficult to be distinguished in the repair pixel at a specific luminance such as a luminance level of 50%. The ratio to the drive signal Vsig set for the normal pixel is obtained. Thereby, in this step, the pixel luminance adjustment amount is obtained.

  Here, in the example of FIG. 8, even if the light emission luminance per unit area in the light emission region of the repair pixel increases to 63, the repair pixel is visually recognized as a dark spot, so the light emission luminance per unit area is further increased. Thus, it is set to 68 in the example of FIG. Thus, in the manufacturing process, the address of the repair pixel and the pixel luminance adjustment amount are stored in the pixel luminance adjustment information unit 22.

[Operation of First Embodiment]
In the above configuration, in the image display device 21 (FIGS. 1 and 22), sequentially input image data D1 is distributed to each signal line, and then subjected to digital-analog conversion processing to set the drive voltage Vsig. In the image display device 21, the drive voltage Vsig is set in each pixel circuit 16 of the display unit 2 in line order by control by the scanning line. More specifically, the inter-terminal voltage of the storage capacitor Cs provided in each pixel circuit 16 is set by this drive voltage Vsig. In the image display device 21, the voltage between the gate and source of the drive transistor Tr1 is set by the voltage across the storage capacitor Cs, and the organic EL element OLED is driven by the drive current due to the voltage between the gate and source of the drive transistor Tr1. Thereby, in the image display device 21, an image based on the image data D1 can be displayed on the display unit 2.

  However, in the image display device 21, a pixel formed by the organic EL element OLED may be a defective pixel due to various factors (see FIG. 22). Therefore, in the image display device 21, defective pixels are detected in the manufacturing process, and the electrode at the site causing the defective pixels is locally removed by laser beam irradiation, reverse bias application, etc., and repair processing is performed. Is executed (FIGS. 2 and 8). As a result, in the image display device 21, in the defective pixel, the part other than the part from which the electrode is removed is set to emit light normally, and the dark spot, the bright spot, and the like due to the defective pixel are set to be inconspicuous. As a result, the image display device 21 can improve the image quality compared to the case where no repair is performed.

  However, when the electrode is locally removed by the repair process in this way, the area of the light emitting region is reduced in the repair pixel as compared with the normal pixel. If the constant current driving of the organic EL element by the driving transistor Tr1 has sufficient constant current characteristics, the organic EL element is driven with the same driving current as that of a normal pixel even if the area of the light emitting region is reduced. Current drive is possible. Therefore, in this case, the repair pixel is driven so that the integrated luminance depending on the area is the same as that of the normal pixel.

  However, in the image display device 21, due to the decrease in the area of the light emitting region, the integrated luminance due to the area in the repair pixel decreases (FIGS. 3 to 5). As a result, in the image display device 21, the repair pixel is visually recognized as a dark spot, and the deterioration of the image quality is perceived as in the case where the defective pixel due to the low luminance pixel is generated.

  For this reason, it is conceivable to increase the light emission luminance per unit area in the repair pixel to make the dark spot inconspicuous. However, simply increasing the light emission luminance of the repair pixel so that the integrated luminance due to the area is the same as that of the normal pixel, this time, the light emitting region and the non-light emitting region in the repair pixel will be perceived. Degradation of image quality is perceived (FIG. 6).

  Therefore, in the image display device 21 (FIG. 7), by adjusting the light emission luminance per unit area of the light emitting region in the repair pixel, the integrated luminance due to the area of the light emitting region in the repair pixel is set to a predetermined value, whereby the luminance of the repair pixel is set. The non-light emitting area of the light emission luminance in the repair pixel is set to be difficult to visually recognize as compared with the case where the adjustment is not performed.

  More specifically, the integrated luminance due to the area of the repair pixel is increased within the range equal to or less than the integral luminance due to the area of the normal pixel, and the light emission luminance of the repair pixel is adjusted, so that the non-light emitting region in the repair pixel is difficult to visually recognize. Is set. In other words, the repair pixel is set to the optimum light emission luminance in a range from the light emission luminance per unit area in the normal pixel to the light emission luminance in which the integrated luminance due to the normal pixel area and the integral luminance due to the repair pixel area are set to be the same. Is done. Thereby, in the image display device 21, it is possible to make it difficult to visually recognize the non-light emitting region and the light emitting region in the repair pixel, and the image quality can be further improved.

  That is, in the image display device 21, in the manufacturing process, the repair pixel position information and information on the correction value (luminance adjustment amount) for correcting the light emission luminance are obtained by the repair process, and these pieces of information are used as the pixel luminance adjustment information section 22. Stored in In the image display device 21, the image data D1 of the repaired pixel is corrected by the information of the corresponding luminance adjustment amount based on the information stored in the pixel luminance adjustment information unit 22, whereby the storage capacitor Cs of the corresponding pixel circuit 16 is corrected. The terminal set to is corrected, and the light emission luminance of the repair pixel is corrected.

<Effect of the first embodiment>
According to the above configuration, the brightness of the defective pixel partially having the non-light emitting area is adjusted, and the non-light emitting area is less visible as compared with the case where the brightness of the defective pixel is not adjusted. The image quality deterioration can be further improved as compared with the conventional case.

  In addition, by adjusting the emission luminance of the defective pixel by increasing the integrated luminance due to the defective pixel area within the range below the integral luminance due to the area of the normal pixel, more specifically, the image quality of the defective pixel compared to the conventional case. Degradation can be further improved.

  In addition, since the defective pixel is a repair pixel, image quality deterioration due to the repair pixel can be improved.

  In addition, since the pixel of the display portion is a light emitting element, and the display portion is an active matrix type display portion using an organic EL element, the present invention is applied to an image display device using the light emitting element. Furthermore, by applying the present invention to an active matrix type image display device using an organic EL element, image quality degradation due to defective pixels can be further improved as compared with the conventional case.

  Further, by storing the position information of the defective pixel and the information of the luminance adjustment amount, and adjusting the luminance of the defective pixel based on this information, it is possible to surely correct defects occurring in various places.

<Second Embodiment>
In the image display device of this embodiment, the organic EL element is driven with a constant voltage, and the light emission time of the organic EL element is varied by a time modulation method to express gradation. Therefore, the pixel circuit of the image display device according to this embodiment includes a storage capacitor that holds the drive voltage set in the signal line, and a control that controls the light emission time of the organic EL element in accordance with the terminal voltage set in the storage capacitor. It is composed of a circuit or the like. The control circuit includes an integration circuit that reduces the terminal voltage set in the storage capacitor at a constant rate, a comparison circuit that determines the terminal voltage of the storage capacitor and controls driving of the organic EL element, and the like. In this embodiment, except that the configuration related to the drive circuit is different, the configuration shown in FIG. 1 and the like is appropriately used in the following, because the configuration is the same as that of the first embodiment. explain.

[Changes in emission luminance due to repair in constant voltage drive]
Here, it is assumed that the organic EL element OLED emits light at a constant voltage (Vdd−Vss). Also in this case, it is assumed that the area ratio which is the area of the non-light emitting region in the repair pixel when the area of the light emitting region of the normal pixel is 1 is α. Further, it is assumed that the non-light emitting region of the repair pixel is non-conductive between the electrodes and is completely non-light emitting, and the remaining region of the repair pixel emits light normally in the same manner as the normal pixel.

  In this case, as shown in FIG. 9, the drive current of the repair pixel is reduced by the non-light emitting area compared to the normal pixel, and the integrated luminance due to the area of the normal pixel and the repair pixel is simply the ratio of the light emitting region. Can be expressed as That is, the integrated luminance L depending on the areas of the normal pixel and the repair pixel can be expressed by the following equation.

  Therefore, in this case, the repaired pixel is visually recognized with the light emission luminance lowered by the non-light emitting area. Therefore, in this case, if the light emission time of the light emitting region in the repair pixel is simply multiplied by 1 / (1−α), the light emission luminance integrated by area and time (hereinafter referred to as integrated luminance by area and time) is normal. It can be set the same as the pixel.

  However, even in this embodiment, if the integrated luminance is simply set to be the same as that of a normal pixel, deterioration of the image quality may be perceived by the repair pixel. Therefore, in this image display device, the light emission time of the repair pixel is corrected so as to satisfy the relational expression (6) by storing information in the pixel luminance adjustment information unit 22. In this case, the integrated luminance due to the area in the equation (6) is applied by replacing it with the integrated luminance due to time and area.

  According to this embodiment, even when the organic EL element is driven with a constant voltage, the same effect as in the first embodiment can be obtained.

<Third Embodiment>
FIG. 10 is a connection diagram showing a pixel circuit applied to the image display device according to the third embodiment of the present invention. The image display apparatus according to this embodiment is configured in the same manner as the image display apparatus according to the first embodiment except that the pixel circuit 36 and related configurations are different.

  Here, in the pixel circuit 36, the cathode of the organic EL element OLED is held at the predetermined voltage Vss1, and the anode of the organic EL element OLED is connected to the source of the drive transistor Tr1. The drain of the drive transistor Tr1 is connected to the power supply Vdd1 through the transistor Tr2 that is turned on / off by the control signal VSCAN2 (i) supplied through the scanning line. The transistors Tr1 and Tr2 are N-channel and P-channel transistors, respectively. Coled is a capacity of the organic EL element OLED, and Csub is an additional capacity in parallel with the capacity Cole of the organic EL element OLED. Accordingly, the pixel circuit 36 sets the transistor Tr2 to the on state, and current-drives the organic EL element OLED with a driving current corresponding to the gate-source voltage of the driving transistor Tr1.

  In the pixel circuit 36, a holding capacitor Cs that holds a gate-source voltage of the driving transistor Tr1 is connected to a gate and a source of the driving transistor Tr1. As a result, as shown in FIG. 11, the pixel circuit 36 supplies the power source Vdd1 to the drive transistor Tr1 via the transistor Tr2 during the light emission period during which the organic EL element OLED emits light (indicated by “light emission” in FIG. 11). Is supplied (FIG. 11B), and the organic EL element OLED is driven by the drive transistor Tr1 with a drive current corresponding to the voltage across the storage capacitor Cs (FIGS. 11E to 11G).

  In the pixel circuit 36, the gate-side end of the storage capacitor Cs is connected to the signal line via the write transistor Tr3 that is turned on / off by the write signal VSCAN1 (i) supplied via the scanning line. Further, the gate-side end of the storage capacitor Cs is set to a predetermined voltage Vofs through the transistor Tr4 that is turned on / off by the write signal VSCAN4 (i) supplied through the scanning line. Further, the source side end of the storage capacitor Cs is set to a predetermined voltage Vini through the transistor Tr5 that is turned on / off by the write signal VSCAN3 (i) supplied through the scanning line. Note that these transistors Tr3 to Tr5 are N-channel transistors.

  In the pixel circuit 36, the transistors Tr3 to Tr5 are kept off during the light emission period (FIGS. 11A, 11C, 11D, and 11G). In the pixel circuit 36, when the light emission period ends and the non-light emission period starts, the transistor Tr2 is set to an off state, whereby supply of the power source Vdd1 to the drive transistor Tr1 is stopped, and the gate voltage Vg of the drive transistor Tr1 and The source voltage Vs falls, and the light emission of the organic EL element OLED stops (FIGS. 11B, 11E, and 11F).

  In the pixel circuit 36, when the non-light emission period starts and a certain time elapses, the transistors Tr4 and Tr5 are set to the on state (FIGS. 11C and 11D), and the terminal voltage of the storage capacitor Cs is Vofs and Vini, respectively. (FIGS. 11E and 11F). Here, the voltages Vofs and Vini are voltages that set the inter-terminal voltage Vofs−Vini of the storage capacitor Cs to a voltage higher than the threshold voltage Vth of the driving transistor Tr1. As a result, as shown by “preparation” in FIG. 11, a preparatory process for preventing image quality deterioration due to variations in the threshold voltage of the drive transistor Tr1 is executed. Hereinafter, the process for preventing the image quality deterioration due to the variation in the threshold voltage of the drive transistor Tr1 is referred to as a threshold voltage correction process.

  Subsequently, in the pixel circuit 36, after the transistor Tr5 is set to the off state, the transistor Tr2 is set to the on state, and the power supply Vdd1 is supplied to the drive transistor Tr1 (FIGS. 11B and 11C). Thus, in the pixel circuit 36, the current corresponding to the voltage across the holding capacitor Cs flows into the organic EL element OLED via the driving transistor Tr1 in a state where the gate side end of the holding capacitor Cs is held at the voltage Vofs. As a result, the pixel circuit 36 gradually decreases the voltage across the storage capacitor Cs due to this current, and when the voltage across the storage capacitor Cs reaches the threshold voltage Vth of the drive transistor Tr1, the current from the drive transistor Tr1. Inflow stops, and the decrease of the voltage across the storage capacitor Cs stops (FIGS. 11E and 11F). Thereby, in the pixel circuit 36, the voltage across the storage capacitor Cs is discharged through the drive transistor Tr1, and the voltage across the storage capacitor Cs is set to the threshold voltage Vth of the drive transistor Tr1. Thus, the pixel circuit 36 executes a threshold voltage correction process (indicated by “Vt complement” in FIG. 11).

  Subsequently, in the pixel circuit 36, after the transistors Tr2 and Tr4 are set to the off state (FIGS. 11B and 11D), the writing transistor Tr3 is set to the on state and the drive voltage output to the signal line is set. Vsig is set to the gate side end of the storage capacitor Cs. Here, the drive voltage Vsig is a voltage obtained by adding the voltage Vofs to the voltage Vdata obtained by subjecting the corresponding image data D1 to digital-analog conversion processing. As a result, the pixel circuit 36 sets the light emission luminance of the organic EL element OLED as indicated by “write” in FIG.

  In the pixel circuit 36, the transistor Tr2 is subsequently set to an on state (FIG. 11B), and after a predetermined time has elapsed, the writing transistor Tr3 is set to an off state (FIG. 11A). As a result, the pixel circuit 36 discharges the voltage across the storage capacitor Cs by the current of the drive transistor Tr1 for a fixed time in a state where the voltage at the gate side end of the storage capacitor Cs is held at the drive voltage Vsig. Here, the discharge rate of the voltage across the storage capacitor Cs increases as the mobility of the drive transistor Tr1 increases. Thus, the pixel circuit 36 corrects the variation in mobility of the drive transistor Tr1 as indicated by “μ complement” in FIG.

  The pixel circuit 36 starts a light emission period by setting the write transistor Tr3 in an off state for the mobility correction, and functions as a so-called bootstrap circuit to increase the gate voltage Vg and the source voltage Vs of the drive transistor Tr1. (FIGS. 11E and 11F).

  Here, the drive current Ids in the light emission period is expressed by the following equation. Here, μ is the mobility of the driving transistor Tr1, and W and L are the gate width and gate length of the driving transistor Tr1. g is a gain at the time of writing, and t correction is a time for correcting variation in mobility.

  Here, a transistor applied to this type of image display device has a feature that variation in threshold voltage and variation in mobility are large. Therefore, when no countermeasure is taken, the image quality deteriorates due to these variations. However, the pixel circuit 36 can prevent image quality deterioration due to variations in threshold voltage and mobility.

  However, in the pixel circuit 36, the inter-terminal voltage set in the holding capacitor Cs via the signal line and the feedback amount in the mobility variation correction process are affected by the capacitance of the organic EL element OLED. As a result, when the repair process is performed, the emission luminance changes in the repair pixel due to a decrease in the capacity of the organic EL element OLED due to the repair. Therefore, it is necessary to set the drive voltage Vsig in consideration of these effects.

[Changes in light emission luminance due to fluctuations in writing gain]
Here, to simplify the description, it is assumed that the pixel circuit 36 operates according to the time chart shown in FIG. 12 in comparison with FIG. Here, the time chart of FIG. 12 omits the process of correcting the mobility variation. In the example of FIG. 12, the write transistor Tr3 is turned off before the transistor Tr2 is turned on to start supplying the power source Vdd1 to the drive transistor Tr1.

  In the example of FIG. 12, the drive current Ids by the drive transistor Tr1 can be expressed by the following equation.

  Here, when the non-light-emitting region having the area ratio α is generated by the repair, the area of the counter electrode is reduced (1−α) times in the organic EL element OLED. Accordingly, the capacitance Coled of the organic EL element OLED is reduced to (1-α) · Coled. Accordingly, the combined capacity C in the equation (10) is reduced by α · Coled, and the gain g is reduced to C−α · Coled−Cs) / (C−α · Coled).

  That is, in the pixel circuit 36, when the writing transistor Tr3 is set to the on state and the gate side end voltage of the storage capacitor Cs is set to the drive voltage Vsig, the storage capacitor Cs is interlocked with the voltage increase at the gate side end of the storage capacitor Cs. The voltage also rises at the source side end. The voltage increase at the source side end is obtained by capacitively dividing the voltage increase at the gate side end voltage. Thereby, in the pixel circuit 36, the effective voltage Vdata set in the storage capacitor Cs depends on the capacitance Coled of the organic EL element OLED.

  Accordingly, when the capacitance Coled of the organic EL element OLED is reduced due to the repair, the inter-terminal voltage set in the storage capacitor Cs also changes. In this case, in the repair pixel, the voltage between the terminals of the storage capacitor Cs is smaller than that of the normal pixel, and the light emission luminance is lowered.

  Therefore, when the drive current Ids of the organic EL element OLED is simply set to be equal between the normal pixel and the repair pixel and the integrated luminance due to the area is made equal, the voltage Vdata obtained by performing the digital-analog conversion processing on the image data D1. Must be corrected as shown by the following equation.

[Changes in light emission luminance due to fluctuations in the amount of negative feedback correction]
Here, to simplify the description, it is assumed that the display unit includes the pixel circuit 46 shown in FIG. 13 and operates according to the time chart shown in FIG. Here, the pixel circuit 46 removes the transistor Tr4 from the configuration of the pixel circuit 36, the voltage set by the transistor Tr5 is Vini, and the voltage Vdata obtained by digital-analog conversion processing of the image data D1 is the direct drive voltage Vsig. It is input to the signal line. Here, the voltage Vini is a voltage obtained by adding the threshold voltage of the organic EL element OLED to the cathode voltage Vss1 of the organic EL element OLED.

  In the pixel circuit 46, when a certain time elapses after the non-light emission period starts, the transistors Tr3 and Tr5 are set to the on state, and the terminal voltage of the storage capacitor Cs is set to Vdata and Vini, respectively. Thereafter, in the pixel circuit 46, the transistor Tr5 is set to an off state. In the pixel circuit 46, the power source Vdd1 is supplied to the driving transistor Tr1 for a predetermined time while the gate side end of the storage capacitor Cs is connected to the signal line, and the mobility of the driving transistor Tr1 is corrected. Is executed.

  Thereby, in the pixel circuit 46, the drive current Ids of the drive transistor Tr1 can be expressed by the following equation.

  Here, when the non-light-emitting region having the area ratio α is generated by the repair, the area of the counter electrode is reduced (1−α) times in the organic EL element OLED. Accordingly, the capacitance Coled of the organic EL element OLED is reduced to (1-α) · Coled. Accordingly, the combined capacity C in the equation (10) is reduced by α · Coled, and the gain g is reduced to C−α · Coled−Cs) / (C−α · Coled). At the same time, the term of β / 2 · C / t correction related to the period for correcting the mobility also changes.

  That is, in the pixel circuit 46, the correction of the inter-terminal voltage of the storage capacitor Cs related to the correction of the mobility is performed by using the drive current corresponding to the mobility of the drive transistor Tr1 for a certain time and the source side end of the storage capacitor Cs as the drive transistor It is executed by charging through Tr1. Accordingly, in the pixel circuit 46, the β / 2 · C / t correction, which is a negative feedback correction amount related to the mobility correction, depends on the capacitance Coled of the organic EL element OLED.

  Therefore, when the capacity of the organic EL element OLED is reduced due to the repair, the inter-terminal voltage set in the storage capacitor Cs also changes. In this case, in the repair pixel, the voltage between the terminals of the storage capacitor Cs is smaller than that of the normal pixel, and the light emission luminance is lowered.

  Therefore, when the drive current Ids of the organic EL element OLED is simply set to be equal between the normal pixel and the repair pixel and the integrated luminance due to the area is made equal, the voltage Vdata obtained by performing the digital-analog conversion processing on the image data D1. Must be corrected as shown by the following equation.

[Changes in emission luminance due to fluctuations in write gain and negative feedback correction amount]
Accordingly, in the pixel circuit 36, the light emission luminance changes in the repair pixel due to the change in the write gain and the negative feedback correction amount. Therefore, in the case where the drive current Ids of the organic EL element OLED is simply set to be equal between the normal pixel and the repair pixel and the integrated luminance due to the area is made equal, the following formulas (11) and (13) are put together. It is necessary to correct as shown by the equation.

  Note that the t correction is a period in which the variation in mobility can be set to the smallest when the voltage Vdata is the specific voltage Vdata0 such as an intermediate gradation. Therefore, the following relational expression is satisfied.

  The t correction is expressed by the following equation obtained by solving equation (9) using the relationship of equation (15).

  Further, the pixel circuit 36 drives the organic EL element OLED by constant current driving by the driving transistor Tr1 in the same manner as described above for the first embodiment. Therefore, in consideration of the characteristics of the drive transistor Tr1 so as to satisfy the relational expression (13), the drive voltage Vsig is corrected by the area ratio α of the non-light-emitting region, whereby the normal pixel and the repair pixel are corrected. The integrated luminance depending on the area can be set to be the same.

  However, in the image display device to which the pixel circuit 36 is applied, as described above with respect to the first embodiment, the light emission luminance per unit area in the repair pixel is simply increased, and the integrated luminance due to the area is normal. If it is set to be the same as the pixel, the light emitting area and the non-light emitting area in the repair pixel are perceived, and the deterioration of the image quality is perceived.

  Therefore, in this image display device, as in the first embodiment, the integrated luminance based on the area of the normal pixel and the integrated luminance based on the area of the repair pixel are set to be the same from the light emission luminance per unit area in the normal pixel. In the range up to the light emission luminance, the light emission luminance per unit area of the light emitting region in the repair pixel is set to the optimum light emission luminance.

  Similar to the third embodiment, the same effect as that of the first embodiment can be obtained even in the case of correcting the variation in the threshold voltage of the driving transistor and in correcting the variation in mobility. be able to.

<Fourth embodiment>
FIG. 15 is a connection diagram showing a pixel circuit applied to the fourth image display device of the present invention. The image display apparatus according to this embodiment is configured in the same manner as the image display apparatus according to the third embodiment except that the pixel circuit 56 and related configurations are different.

  Here, in the pixel circuit 56, the cathode of the organic EL element OLED is held at the predetermined voltage Vss1, and the anode of the organic EL element OLED is connected to the source of the drive transistor Tr1. In the pixel circuit 56, the drive signal VSCAN2 (i) is supplied to the drain of the drive transistor Tr1 through the scanning line. In the pixel circuit 56, a holding capacitor Cs that holds a gate-source voltage of the driving transistor Tr1 is connected to a gate and a source of the driving transistor Tr1.

  In the pixel circuit 56, the drive signal VSCAN2 (i) is set to the power supply voltage Vddv2 during the light emission period (FIG. 16B). As a result, during the light emission period, the pixel circuit 56 current-drives the organic EL element OLED with the drive transistor Tr1 by the drive current based on the gate-source voltage based on the voltage across the storage capacitor Cs.

  In the pixel circuit 56, the gate-side end of the storage capacitor Cs is connected to the signal line via the write transistor Tr3 that is turned on / off by the write signal VSCAN1 (i) supplied via the scanning line. Further, the drive voltage Vsig (= Vofs + Vdata) is sequentially output to the signal line with a predetermined fixed voltage Vofs interposed therebetween (FIG. 16C).

  In the pixel circuit 56, when the non-light emission period starts, the drive signal VSCAN2 (i) is set to the predetermined voltage Vssv2. Here, the voltage Vssv2 is a sufficiently low voltage to cause the source of the driving transistor Tr1 to function as a drain (FIGS. 16A and 16F). Thus, when the non-light emission period starts, the pixel circuit 56 discharges the accumulated charge of the organic EL element OLED via the driving transistor Tr1, the anode voltage of the organic EL element OLED falls, and the organic EL element OLED stops emitting light. (FIGS. 16D and 16E). Further, the voltage at the source side end of the storage capacitor Cs is set to the voltage Vssv2 and is set to a sufficiently low voltage.

  Subsequently, in the pixel circuit 56, the writing transistor Tr3 is set to the on state and the voltage at the gate side end of the storage capacitor Cs is set to the voltage Vofs during the period in which the signal line is set to the voltage Vofs (FIG. 16 (A)). Thereby, in the pixel circuit 56, the voltage across the storage capacitor Cs is set to the voltage Vofs−Vssv2. Here, in the pixel circuit 56, the voltages Vofs and Vssv2 are set so that the voltage Vofs−Vssv2 is sufficiently larger than the threshold voltage Vth of the driving transistor Tr1 (FIGS. 16D and 16E). ). In addition, a period from when the non-light emission period starts to when the voltage at the gate side end of the storage capacitor Cs is set to the voltage Vofs is set as a preparation process period for the threshold voltage variation correction process of the drive transistor Tr1. (FIG. 16F).

  In the pixel circuit 56, the drive signal VSCAN2 (i) is then set to the power supply voltage Vddv2 (FIG. 16B). As a result, the pixel circuit 56 discharges the voltage across the storage capacitor Cs via the drive transistor Tr1, and the voltage across the storage capacitor Cs is set to the threshold voltage Vth of the drive transistor Tr1.

  Subsequently, in the pixel circuit 56, after the write transistor Tr3 is set to the off state, the write transistor Tr3 is set to the on state for a predetermined period in a period in which the signal line is set to the drive voltage Vsig. . As a result, the pixel circuit 56 executes processing for correcting the variation in mobility of the drive transistor Tr1, and sets the gradation of the organic EL element OLED by setting the voltage at the gate end of the storage capacitor Cs to the gradation voltage Vsig. To do.

[Changes in luminance]
In the pixel circuit 56, the drive current of the drive transistor Tr1 is expressed by equation (9). Therefore, similarly to the pixel circuit 36 of the third embodiment, when the capacitance Coled of the organic EL element OLED is reduced by the repair pixel, the inter-terminal voltage set in the holding capacitor Cs also changes. In this case, in the repair pixel, the voltage between the terminals of the storage capacitor is smaller than that of the normal pixel, and the light emission luminance is lowered.

  Therefore, when the drive current Ids of the organic EL element OLED is set and the normal pixel and the repair pixel are set equal to make the integrated luminance equal to the area, the voltage Vdata is corrected so as to satisfy the equation (14). Is required. Furthermore, when the emission luminance per unit area in the repair pixel is increased and the integrated luminance due to the area is set to be the same as that of the normal pixel, the light emitting region and the non-light emitting region in the repair pixel are perceived. Therefore, degradation of image quality is perceived.

  Therefore, in this image display device, as in the first embodiment, the integrated luminance based on the area of the normal pixel and the integrated luminance based on the area of the repair pixel are set to be the same from the light emission luminance per unit area in the normal pixel. In the range up to the light emission luminance, the light emission luminance per unit area of the light emitting region in the repair pixel is set to the optimum light emission luminance.

  As in the fourth embodiment, the pixel circuit is composed of two transistors, and the drain voltage of the driving transistor and the voltage between the terminals of the storage capacitor are controlled by the control of the writing transistor to a voltage equal to or higher than the threshold voltage of the driving transistor. Even when the variation in threshold voltage of the driving transistor is corrected by setting to, the same effect as in the first embodiment can be obtained.

<Fifth embodiment>
FIG. 17 is a block diagram showing an image display apparatus according to the fifth embodiment of the present invention. This image display device 61 is the first to fourth embodiments except that a pixel luminance adjustment information unit 62 and a luminance adjustment calculation circuit 63 are provided instead of the pixel luminance adjustment information unit 22 and the luminance adjustment calculation circuit 23. The same configuration as that of the image display apparatus is provided.

  The pixel brightness adjustment information section 62 records position information, area ratio of the non-light emitting area, or information on the area ratio of the non-light emitting area and the brightness adjustment amount for each repair pixel. The luminance adjustment calculation circuit 63 corrects the image data D1 corresponding to the repair pixel by the calculation process using the information recorded in the pixel luminance adjustment information unit 62, as in the first to fourth embodiments. To set the drive voltage. As indicated by parentheses, the function itself used for correcting the image data D1 may be stored in the pixel luminance adjustment information section.

  According to this embodiment, by correcting the light emission luminance of the repair pixel by the arithmetic processing using the area ratio of the non-light emission region, or the area ratio of the non-light emission region and the luminance adjustment amount, the repair pixel is more appropriately corrected. Light emission brightness can be corrected to further improve image quality degradation.

<Sixth Embodiment>
FIG. 18 is a block diagram showing an image display apparatus according to the sixth embodiment of the present invention. This image display device 71 is the first to fourth embodiments except that a pixel luminance adjustment information unit 72 and a luminance adjustment calculation circuit 73 are provided instead of the pixel luminance adjustment information unit 22 and the luminance adjustment calculation circuit 23. The same configuration as that of the image display apparatus is provided.

  Similar to the first to fourth embodiments, the pixel brightness adjustment information unit 72 detects optimal brightness adjustment amounts at the brightness levels of 100 [%] and 10 [%], and this brightness is adjusted for each repair pixel. The adjustment amount is recorded. The luminance adjustment calculation circuit 63 obtains a luminance adjustment amount corresponding to the gradation set in the repair pixel by linear interpolation using the luminance adjustment amount information recorded in the pixel luminance adjustment information section 72. In addition, a drive voltage is generated by multiplying the corresponding image data D1 by the obtained luminance adjustment amount, thereby correcting the light emission luminance of the repair pixel. Note that various calculation methods can be applied instead of linear interpolation calculation processing, such as when calculating the brightness adjustment amount by interpolation calculation processing using a quadratic function, or further by calculation processing using an insulator function. . Also in this case, as indicated by parentheses, the function itself used for correcting the image data D1 may be stored in the pixel luminance adjustment information section.

  According to this embodiment, by correcting the light emission luminance of the repair pixel by the interpolation calculation process using the luminance adjustment amount, the light emission luminance of the repair pixel can be corrected more appropriately, and the image quality deterioration can be further improved.

<Seventh embodiment>
By the way, in the repair pixel, the light emission luminance per unit area increases as compared with the normal pixel, and as shown in FIG. Therefore, even if the light emission luminance of the repair pixel is initially set optimally, it may be visually recognized as a dark spot over time. Therefore, the image display apparatus according to this embodiment measures the elapsed time from the start of use by a built-in timer. Furthermore, the light emission luminance of the repair pixel is set by correcting the initially set luminance adjustment amount of the repair pixel based on the elapsed time. As a result, even when time elapses, the light emission luminance of the repair pixel is optimally set.

  That is, when the light emission luminance per unit area is set to 1 / (1-α) times, the light emission luminance L (luminance adjustment 1 / (1-α) times, T) when the time T has elapsed is L ( It is represented by a normal pixel, (((1-α) / 1) β) · T). Here, β is an acceleration coefficient. Therefore, by setting the brightness adjustment amount to {L (normal pixel, (((1-α) / 1) β) · T)} / {L (normal pixel, (T)} times, time has elapsed. Even in this case, the light emission luminance of the repair pixel can be set optimally.

According to the above configuration, the image quality can be further improved by increasing the correction amount of the light emission luminance of the repair pixel with the passage of time and preventing the light emission luminance from decreasing due to the change with time of the repair pixel with respect to the normal pixel. .
<Modification>
In the above-described embodiment, the case has been described in which the information on the brightness adjustment amount is held only for the repair pixel. However, the present invention is not limited to this, and information on the luminance adjustment amount may be held for all the pixels on the display screen or for all the pixels in the predetermined area of the display screen. In this case, it is possible to further improve the image quality by recording the brightness adjustment amount information for shading correction together.

  In the above-described embodiment, the case where defective pixels observed as dark spots and bright spots are repaired has been described. However, the present invention is not limited to this, and can be widely applied to a case where a region where characteristic deterioration due to a change with time is locally different is set as a non-light emitting portion by repair.

  In the above-described embodiment, the case where the light emission luminance of the repair pixel is corrected is described on the assumption that the defective pixel observed as the dark spot or the bright spot is repaired. However, the present invention is not limited to this, and can be widely applied even when repair processing is not performed. That is, the image quality can be improved by applying the present invention to a defective pixel having a region with a low emission luminance and a defective pixel having a partial emission luminance.

  In the second embodiment described above, the case where the gradation is expressed by the time modulation method has been described. However, the present invention is not limited to this and is widely applied to the case where the gradation is expressed by the area modulation method. be able to.

  In the above-described embodiment, the case where the present invention is applied to an active matrix image display device using an organic EL element has been described. However, the present invention is not limited to this, and can be widely applied to a passive matrix image display device using organic EL elements, an image display device using light emitting elements other than organic EL elements, and the like.

  The present invention can be applied to an image display device using an organic EL element.

1 is a block diagram illustrating an image display device according to a first embodiment of the present invention. It is a top view with which it uses for description of a repair pixel. It is a characteristic curve figure used for description of the constant current drive of an organic EL element. It is a characteristic curve figure which shows the organic EL element characteristic of a repair pixel. It is a characteristic curve figure with which it uses for description of the light emission luminance in a repair pixel. It is a top view with which it uses for description of the light emission luminance in a repair pixel. It is a top view with which it uses for description of optimal light-emitting luminance. It is a top view with which it uses for description of specific light-emitting luminance. It is a characteristic curve figure with which it uses for description of the constant voltage drive of an organic EL element. It is a connection diagram which shows the pixel circuit of the image display apparatus which concerns on the 3rd Embodiment of this invention. 11 is a time chart for explaining the operation of the pixel circuit of FIG. 10. It is a time chart with which it uses for description of the change of the light emission luminance by the fluctuation | variation of a write gain. It is a connection diagram with which it uses for description of the change of the light-emitting luminance by repair in constant current drive. It is a time chart with which it uses for description of the change of the light emission luminance by the fluctuation | variation of the negative feedback correction amount. It is a connection diagram which shows the pixel circuit applied to the 4th image display apparatus of this invention. FIG. 16 is a connection diagram for explaining the operation of the pixel circuit of FIG. 15. It is a block diagram which shows the image display apparatus which concerns on the 5th Embodiment of this invention. It is a block diagram which shows the image display apparatus which concerns on the 6th Embodiment of this invention. It is a characteristic curve figure with which it uses for description of operation | movement of the image display apparatus which concerns on the 6th Embodiment of this invention. It is a block diagram which shows the conventional image display apparatus. It is a connection diagram for explanation of a passive matrix type image display device. It is a connection diagram for explanation of an active matrix type image display device. It is sectional drawing with which it uses for description of a repair process.

Explanation of symbols

1, 21, 61, 71... Image display device, 2... Display unit, 3... Drive circuit, 22, 62, 72... Pixel brightness adjustment information unit, 23, 63, 73. 36, 46: Pixel circuit, Cs: Retention capacitor, OLED: Organic EL element, Tr1 to Tr5: Transistor

Claims (11)

A display section in which pixels are arranged in a matrix,
Driving the pixels arranged in the display unit according to image data, and displaying a desired image on the display unit,
The drive unit is
Having a luminance adjustment unit for adjusting the luminance of defective pixels partially having a low luminance region or a non-light emitting region;
The luminance adjustment unit sets the integrated luminance based on the area of the defective pixel, or the integrated luminance based on the area and time of the defective pixel, compared to the case where the luminance adjustment unit does not adjust the luminance of the defective pixel. An image display device that makes it difficult to visually recognize an area with low emission luminance or a non-light emission area. The brightness adjusting unit is
The emission luminance per unit area in the corresponding normal pixel is set to the emission luminance per unit area in the emission region of the defective pixel within the range of the integrated luminance due to the area in the normal pixel or the integration luminance due to the area and time in the normal pixel. The image display device according to claim 1, wherein the emission luminance of the defective pixel is adjusted by increasing the luminance. The image display device according to claim 2, wherein the defective pixel is a repair pixel. The image display apparatus according to claim 2, wherein the pixel is a light emitting element. The image display device according to claim 2, wherein the display unit is a passive matrix display unit using an organic EL element. The image display apparatus according to claim 2, wherein the display unit is an active matrix type display unit using an organic EL element. The brightness adjusting unit is
Storage means for storing position information of the defective pixel and information on a luminance adjustment amount of the defective pixel;
The image display device according to claim 1, wherein brightness of a defective pixel is adjusted based on the position information and brightness adjustment amount information held in the storage unit. The brightness adjusting unit is
Storage means for storing the position information of the defective pixel and the area ratio information of the non-light-emitting area of the defective pixel, or the area ratio of the non-light-emitting area and the brightness adjustment amount;
The image display apparatus according to claim 1, wherein brightness of a defective pixel is adjusted based on information stored in the storage unit. The brightness adjusting unit is
Furthermore, it has a time measurement unit that measures elapsed time,
The image display apparatus according to claim 1, wherein a luminance change due to a temporal change of the defective pixel with respect to a normal pixel is corrected based on an elapsed time measured by the time measurement unit. The display unit
A light emitting element for forming the pixel;
A driving transistor for driving the light emitting element with a driving current according to a gate-source voltage;
A holding capacitor for holding the gate-source voltage;
The image display device according to claim 1, further comprising: a writing transistor that sets a voltage at one end of the storage capacitor to a voltage of a signal line. A display section in which pixels are arranged in a matrix,
A driving method of an image display device that drives a pixel arranged in the display unit in accordance with image data and displays a desired image on the display unit,
The integrated luminance depending on the area of the defective pixel partially having a low luminance area or a non-light emitting area, or the integrated luminance depending on the area and time of the defective pixel is adjusted, and the luminance adjustment unit does not adjust the luminance of the defective pixel. A method for driving an image display apparatus, comprising: a step of adjusting light emission luminance that makes it difficult to visually recognize the low light emission luminance region or the non-light emission region.

Images