Patent Grant
8569958
1. Field of the Invention
The present invention relates to an electroluminescent panel (hereinafter, simply referred to as panel) sealing a light emitting element formed over a substrate between the substrate and a cover member. Further, the invention relates to an electroluminescent module where an IC including a controller is mounted over the panel. Further, in the specification, both of the panel and the electroluminescent module are generally referred to as luminescent device.
2. Description of the Related Art
A light emitting element spontaneously emits light and therefore, having high visibility, dispensing with a backlight needed in a liquid crystal display display (LCD), optimum for thin formation and not restricted in viewing angle. Therefore, in recent years, a luminescent device using a light emitting element attract attention as a display device substituting for CRT or LCD.
Further, in the specification, a light emitting element generally includes an element luminance of which is controlled by current or voltage and includes an electron source element (electron discharge element) of MIM type used in OLED (Organic Light Emitting Diode) or FED (Field Emission Display).
OLED which is one of light emitting elements includes a layer including a compound providing electroluminescence generated by applying an electric field (electroluminescent material) (hereinafter, referred to as electroluminescent layer), an anode layer and a cathode layer. As luminescence in the electroluminescent material, there are luminescence in returning from a singlet excited state to a ground state (fluorescence) and luminescence in returning from a triplet excited state to the ground state (phosphorescence).
The electroluminescent layer specifically includes a light emitting layer, a hole injecting layer, an electron injecting layer, a hole transporting layer and an electron transporting layer. OLED is basically constructed by a structure of successively laminated anode/light emitting layer/cathode and, other than the structure, may be constructed by a structure of successively laminated anode/hole injecting layer/light emitting layer/cathode, or anode/hole injecting layer/light emitting layer/electron transporting layer/cathode. Further, an inorganic compound may be included in the layers.
Meanwhile, lowering of luminance of OLED in accordance with a deterioration in an electroluminescent material poses a serious problem in putting light emitting devices into practical use.
Further,
In most cases, gray scale displayed at each pixel differs by an image and therefore, in the case of a time gray scale system using a digital video signal, a period of emitting light by a light emitting element differs among pixels. Further, even in the case of using an analog video signal, a period of emitting light by a light emitting element and an amount of current supplied to a light emitting element differ among pixels. Therefore, the deterioration of the light emitting element of each pixel differs with elapse of time and luminance is dispersed.
Lowering of the luminance of the light emitting element by the deterioration can be compensated for by increasing current supplied to the light emitting element or increasing drive voltage. However, it is not realistic to provide a power source for supplying voltage or current in correspondence with each pixel and therefore, actually, a common power source for supply voltage or current for all of pixels or a certain number of pixel is provided. When voltage or current supplied from the common power source is simply increased to compensate for lowering of luminance of a light emitting element in accordance with the deterioration, in all of pixel supplied with the voltage or current, luminance of light emitting elements is increased on an average and a dispersion in luminance among pixels cannot be resolved.
In order to resolve the dispersion of luminance among pixels caused by deterioration, according to Patent reference 1, mentioned below, it is described to maintain luminance of a screen to be equivalent to that before deterioration by counting an accumulated period of lighting a light emitting element and preserving the period in a memory and correcting a video signal based on data of a previously prepared deterioration characteristic.
Japanese Patent Laid-Open No. 2002-175041
However, the dispersion of luminance among pixels is not only caused by the deterioration but also by a dispersion in a characteristic of TFTs among pixels as explained below.
In the case of a light emitting device of an active matrix type, current flowing in a light emitting element of each pixel is controlled by a thin film transistor (TFT) similarly provided to each pixel.
The gate of the switching TFT 5000 is connected to a scanning line 5004. One of the source and the drain is connected to a signal line 5005 and other thereof is connected to the gate of the driving TFT 5001. One of the source and the drain of the driving TFT 5001 is connected to a power source line 5006 and the other thereof is connected to a pixel electrode (anode or cathode) provided to the light emitting element 5002. One of two electrodes provided to the storage capacitor is connected to the power source line 5006 and other thereof is connected to the gate of the driving TFT 5001.
Further, in the specification, connection signifies electric connection unless specified otherwise.
Switching of switching TFT 5000 is controlled by voltage applied to the scanning line 5004. When the switching TFT 5000 is made ON, a video signal inputted to the signal line 5005 is inputted to the gate of the driving TFT 5001. Further, current of an amount in correspondence with the video signal inputted to the gate of the driving TFT 5001 is supplied to the light emitting element 5002 to thereby control luminance of the light emitting element 5002.
When a characteristics of the driving TFT 5001 for supplying current to the light emitting element 5002 are dispersed among pixels, current applied to the light emitting element 5002 is also dispersed. That is, the dispersion in the characteristic of the driving TFT 5001 causes dispersion of the luminance among pixels.
According to technology described in Patent reference 1, dispersion of luminance caused by dispersion of a characteristic of TFT cannot be restrained.
It is a purpose of the invention in view of the over-described to provide a light emitting device capable of restraining nonuniformity of luminance caused by a deterioration in an field light emitting layer or a dispersion in a TFT characteristic among pixels and capable of restraining a reduction in the luminance of a total of a screen and a production system of the light emitting device.
According to the invention, in view of the over-described problem, the following means are provided.
According to the invention, in order to restrain nonuniformity of luminance by a deterioration of an electroluminescent layer and nonuniformity of luminance by a dispersion of characteristics of driving TFTs, a correcting circuit for correcting a video signal supplied to each pixel is provided to a light emitting device. The correcting circuit may be fabricated along with TFT over an element substrate on over which a light emitting element and a TFT are formed, or may be formed separately and mounted to a panel.
The correcting circuit is stored with data of a dispersion of characteristics of driving TFTs among pixels and data of a change over time of luminance of the light emitting elements. Further, based on the two data, a video signal inputted to the light emitting device is corrected in conformity with the characteristic of the driving TFT of each pixel and a degree of the deterioration of the light emitting element such that nonuniformity of luminance is not caused.
Data of the variation of the characteristic of the driving TFT is stored into the correcting circuit by a maker before delivering the light emitting device as a product, that is, before being used by an end user. Specifically, a light emitting element is sealed between a substrate and a cover member and completed as a panel and thereafter, current flowing to the light emitting element of each pixel is successively measured. Data including the dispersion of the characteristics of the driving TFT provided by the measurement as information are successively written to a volatile memory.
Further, data stored to the volatile memory is written to a nonvolatile memory inside the correcting circuit to store. The correcting device is provided with a function of correcting video signals inputted to the light emitting device based on data of the dispersion of the characteristics of the driving TFTs stored in the nonvolatile memory. For example, when ON current is small and a gray scale lower than a desired value is displayed, the video signal is corrected to increase a number of the gray scale. Conversely, when the ON current is large and a gray scale higher than a desired value is displayed, the video signal is corrected to reduce the number of gray scale.
Therefore, when used by the end user, based on the data of the dispersion of the characteristics of the driving TFTs previously stored by the maker, the video signals are corrected for respective pixels and nonuniformity of luminance by the dispersion of the driving TFTs is restrained.
Further, the volatile memory used in measuring the current flowing in the light emitting element of each pixel successively is not needed after writing data of the dispersion of the characteristics of the driving TFTs provided as information to the nonvolatile memory inside the correcting circuit and therefore, it is preferable to separate the volatile memory from the light emitting device before conveyed to the end user by being delivered as a product.
Further, in the correcting device, a video signal supplied to the light emitting device is sampled always or periodically. Further, a gray scale displayed at each pixel is detected from a period of making the light emitting element of each pixel emit light or an amount of current supplied to the light emitting element. Successively, one pixel constituting a reference is selected, an accumulated value (sum) of the detected value and data of a change over time of the luminance of the light emitting element previously stored are compared and supplied voltage is corrected to thereby provide desired luminance at the pixel. A designer can pertinently set the pixel constituting the reference.
For example, when the reference is constituted by a pixel which is most significantly deteriorated to reduce luminance, other pixel supplied with voltage from a power source common to that of the pixel which is most significantly deteriorated is supplied with a excessively high voltage and therefore, it seems that the luminance becomes higher than that of the pixel which is most significantly deteriorated and a number of gray scale is increased. In these pixels, by comparing the accumulated value of the detected value of each pixel and previously stored data of the change over time of the luminance of the light emitting element, the video signals inputted to the deteriorated pixels of the light emitting elements is corrected at each time and the number of gray scales are reduced.
Conversely, when the correction is carried out by constituting a reference by a pixel which is least deteriorated, by comparing an accumulated value of the detected value of the pixel and previously stored data of a change over time of luminance of the light emitting element, voltage supplied to the pixel is corrected to provide desired luminance. On this occasion, in other pixel supplied with voltage from a power source common to that of the pixel which is least deteriorated, voltages to be supplied is still deficient and therefore, it seems that the luminance is lower than that of the pixel which is least deteriorated and the number of gray scales stay to be lower than desired values. In these pixels, by comparing the accumulated value of the detected value of each pixel and previously stored data of a change over time of the luminance of the light emitting element, the video signal inputted to the deteriorated pixel of the light emitting element is corrected at each time and the number of gray scale is increased.
That is, in the pixel which is more deteriorated than the pixel constituting the reference, the video signal may be corrected to increase the number of gray scale and in the pixel which is less deteriorated, the video signal may be corrected to reduce the number of gray scale.
By the over-described constitution, even when the degrees of deterioration of the light emitting elements in pixels differ respectively, uniformity of luminance of a screen can be maintained without bringing about nonuniformity of luminance and further, the reduction of the luminance by the deterioration can be restrained.
Further, the light emitting element used in the invention can take also a mode in which a hole injecting layer and an electron injecting layer, a hole transporting layer or an electron transporting layer are formed by a material of an inorganic compound per se or an organic compound mixed with an inorganic compound. Further, portions of the layers may be mixed to each other.
A constitution of a light emitting device of the invention will be explained as follows.
The panel 101 shown in
The pixel portion 104 is provided with a plurality of pixels having light emitting elements. Only a single pixel 106 is shown in
A predetermined voltage difference is produced between the power source supply line 113 and the opposed electrode of the light emitting element 109 by the voltage source 105. Further, current flowing between the power source supply line 113 and the opposed electrode of the light emitting element 109 can be measured by an ammeter 114.
Further, the pixel shown in
Meanwhile, the correcting circuit 100 includes a monitoring portion 115 for monitoring a light emitting period of the light emitting element of each pixel or an amount of current flowing to the light emitting element from an inputted video signal, a pixel characteristic correcting data storing portion (first storing means) 116 for storing data having a dispersion in a characteristic of the driving TFT of each pixel as information, a deterioration characteristic correcting data storing portion (second storing portion) 117 for storing a change over time of the luminance of the light emitting element or a change in the luminance of the light emitting element relative to the current amount as data, and a voltage correcting circuit 118 for controlling voltage supplied from the voltage source 105. The monitoring portion 115 specifically includes a counter portion 120, a volatile memory for video signal 121 and a nonvolatile memory for video signal 122. Further, there is provided a video signal correcting circuit 119 capable of correcting the inputted video signal, changing the luminance of the light emitting element of each pixel or changing the light emitting period.
Both of the pixel characteristic correcting data storing portion 116 and the deterioration characteristic correcting data storing portion 117 are constituted by nonvolatile memories.
Further, numeral 123 designates a volatile memory for pixels which is a portion for temporarily storing the amount of current flowing to the light emitting element 109 of each pixel measured by the ammeter 114.
Next, operation of the correcting circuit 100 will be explained. First, at a time point of completing the panel, the current flowing to the light emitting element of each pixel is monitored and a dispersion in the characteristic of the driving TFT is grasped.
Predetermined voltage is applied between the opposed electrodes of the light emitting elements 109 of the respective pixels 106 and the power source lines V1 through Vx by the voltage source 105. Further, current between the opposed electrodes of the light emitting elements 109 and the power source lines V1 through Vx can be measured by the ammeter 114.
The voltage source 105 is a variable power source by which voltage supplied to circuit or element is made variable.
Further, the ammeter 114 and the voltage source 105 may be formed over a substrate different from the element substrate formed with the pixel portion 104 or may be formed over an element substrate identical to that of the pixel portion 104 when fabrication thereof is possible.
Further, in the case of a colored display system, the power source and the ammeter may be provided for each color and voltage supplied from the voltage source may be varied for each color.
Further, the light emitting elements 109 of the respective pixels are made to emit light successively and current flowing between the opposed electrodes of the light emitting elements 109 and the power source lines V1 through Vx are successively measured by the ammeter 114. On this occasion, in order to measure an accurate current amount of each pixel, after measuring current, before making a succeeding one of the pixel of the light emitting element emit light, it is necessary to prevent the light emitting element of the measured pixel from emitting light.
That is, the current is measured in a state in which the light emitting element is made to emit light by inputting a video signal for monitoring for making the light emitting element emit light to the pixel and thereafter, a video signal for monitoring for finishing light emittance of the light emitting element is inputted to the pixel to thereby forcibly finish light emittance. Further, the operation is repeated successively for all of the pixels.
Further, the designer can pertinently determine an order of the pixels for measuring the current and it is necessary to determine voltage of the signal inputted to each wiring in accordance with the order of measuring the pixels.
The current amounts of the respective pixels are successively stored to the volatile memory for pixels 123. Further, when the measurement has partially or totally finished, data of the current amounts of the respective pixel stored to the volatile memory for pixels 123 is stored to the pixel characteristic correcting data storing portion 116 provided to the correcting circuit 100. Further, as for data stored to the pixel characteristic correcting data storing portion 116, data of the current amounts of the respective pixels may be included as information and data of the current amounts of the respective pixels may be regarded to include the dispersion in the characteristic of the driving TFT of each pixel as data.
It is necessary to store the data stored to the pixel characteristic correcting data storing portion 116 continuously even after the power source of the light emitting device is made OFF and therefore, it is preferable to use a nonvolatile memory. A write period of a volatile memory is shorter than that of a nonvolatile memory and a number of times of writing of a nonvolatile memory is generally limited and therefore, it is preferable to carry out storing operation successively by using the volatile memory for pixels 123 in measuring the current and write data to the pixel characteristic correcting data storing portion 116 which is a nonvolatile memory after finishing the measurement partially or totally.
After storing data of the current amount of each pixel to the pixel characteristic correcting data storing portion 116, the volatile memory for pixels 123 and the ammeter 114 are not needed. The volatile memory for pixels 123 and the ammeter 114 may be removed in shipping the light emitting device as a product.
The correcting circuit 100 is provided with a function of correcting a video signal to make gray scales of respective pixels uniform by grasping dispersion of current of each pixel from the data stored to the pixel characteristic correcting data storing portion 116.
Specifically, a current value constituting a reference is predetermined and a video signal is corrected to reduce a number of gray scale of a pixel in which current larger than the current value constituting the reference flows and increase a number of gray scale in a pixel in which current smaller than the current value constituting the reference flows.
Further, the designer can pertinently set which current value is used as the reference for correcting video signals. For example, the reference may be determined by an average value of current amounts of all of the pixels or a certain number of the pixel selected irregularly, or the reference may be determined by the largest or the smallest current amount, or the reference may be determined by a current amount previously determined by calculation. A memory for storing the current value constituting the reference may be separately provided, according to which current amount constitutes the reference.
Meanwhile, with regard to the light emitting element used in the light emitting device, data of the change over time of the luminance or data of the change of the luminance relative to the current amount is previously stored in the deterioration characteristic correcting data storing portion 117. The data stored to the deterioration characteristic correcting data storing portion 117 are not limited to these ones and may include information capable of predicting the number of gray scale of each pixel which will be changed by deterioration of the light emitting element in a procedure of using the light emitting device by an end user by comparing the data with information provided from the video signal.
The data stored to the deterioration characteristic correcting data storing portion 117 is used in correcting the voltage supplied from the voltage source 105 to the pixel and a video signal mainly in accordance with a degree of deterioration of the light emitting element of each pixel, although an explanation thereof will be given later.
When necessary data are respectively written to the pixel characteristic correcting data storing portion 116 and the deterioration characteristic correcting data storing portion 117 in this way and a product is completed as a light emitting device, the light emitting device is delivered to the end user and actually displays an image. Next, correction of the video signal when the image is displayed will be explained.
When the video signal is supplied to the light emitting device, the correcting circuit 100 samples the video signal supplied to the light emitting device always or periodically (for example, at each second) and counts information with regard to the number of gray scale of the light emitting period or the current amount of the light emitting element in each element based on information included in the video signal in the counter portion 120. Here, the counted information with regard to the number of gray scale in each pixel is successively stored to a memory as data. Here, it is necessary to accumulate to store the information with regard to the number of gray scale and therefore, it is preferable to use a nonvolatile memory. However, a number of times of writing a nonvolatile memory is generally limited and therefore, as shown by
Further, as a volatile memory, a static type memory (SRAM), a dynamic type memory (DRAM) or a ferroelectric memory (FRAM) are cited. However, the invention is not limited thereto but may be constituted by using any type of memory. Similarly, also with regard to a nonvolatile memory, the invention may be constituted by using a nonvolatile memory generally used including a flash memory. However, when DRAM is used for a volatile memory, it is necessary to add a periodically refreshing function.
Data obtained by accumulating information with regard to the number of gray scale of the light emitting period or the current amount stored to the volatile memory for video signal 121 or the nonvolatile memory for video signal 122 is inputted to the video signal correcting circuit 119 and the voltage correcting circuit 118.
The voltage correcting circuit 118 compares data of the change over time of the luminance, data of the change of the luminance relative to the current amount, or the like, which are previously stored to the deterioration characteristic correcting data storing portion 117 with data obtained by accumulating the information with regard to the number of gray scale of each pixel stored to the nonvolatile memory for video signal 122 and grasps a degree of deterioration of each pixel. Further, a specific pixel which is most significantly deteriorated is detected and a value of the voltage supplied from the voltage source 105 to the pixel portion 104 is corrected in accordance with a degree of deterioration of the specific pixel. Specifically, a value of voltage applied to the light emitting element is increased such that the desired gray scale can be displayed in the specific pixel.
The value of the voltage supplied to the pixel portion 104 is corrected in accordance with the specific pixel and therefore, in other pixels which are less deteriorated than the specific pixel, excessively high voltage is supplied to light emitting elements and desired gray scales are not achieved. Hence, in the video signal correcting circuit 119, video signals for determining gray scales of other pixels are corrected. The video signal correcting circuit 119 is inputted with the video signal other than the data obtained by accumulating the information with regard to the number of gray scale of each pixel. The video signal correcting circuit 119 compares the data of the change over time of the luminance or the change of the luminance relative to the current value previously stored to the deterioration characteristic correcting data storing portion 117 with the data obtained by accumulating the information with regard to the number of gray scale of each pixel and grasps the degree of deterioration of each pixel. Further, according to the embodiment, a specific pixel which is most significantly deteriorated is detected and the inputted video signals are corrected in accordance with a degree of deterioration of the specific pixel. Specifically, the video signals are corrected such that desired numbers of gray scale are achieved. The corrected video signals are inputted to the signal line drive circuit 102. Further, as described over, according to the video signal correcting circuit 119, the video signals are corrected such that the dispersion of the current amount of each pixel detected at the time point of fabricating the panel and stored to the pixel characteristic correcting data storing portion 116 is also correct in addition to the over-described correction of deterioration.
Further, the specific pixel is not limited to a pixel which is most significantly deteriorated and may be a pixel which is Least deteriorated or an arbitrary pixel determined by the designer. In any pixel to be selected, with the pixel as a reference, the value of the voltage supplied from the voltage source 105 to the pixel portion 104 is determined, at a pixel which is more deteriorated than the specific pixel, the video signal is corrected to increase the number of gray scale and in a pixel which is not deteriorated than the specific pixel, the video signal is corrected to reduce the number of gray scale.
Specifically, in the case of the light emitting device shown in
Further, although in
Further, when the light emitting element is further deteriorated, voltage applied to the light emitting element is unlimitedly increased. When the voltage applied to the light emitting element becomes excessively large, the light emitting element is accelerated to deteriorate and occurrence of a portion which does not emit light (dark spot) is facilitated. Hence, according to the invention, as shown by
Further, the constitution of the light emitting element according to the invention is not limited to the constitution illustrated in
Further, according to the light emitting element of the invention, data stored to the volatile memory for video signal 121 may be added to data stored to the nonvolatile memory for video signal 122 to store on shutting down the power source. Thereby, after making the power source ON at the next time, the light emitting period or data accumulated with the number of gray scale of the light emitting element is continuously collected.
As described over, by sampling the video signal always or periodically and storing the data obtained by accumulating the information with regard to the number of gray scale of each pixel, the video signal is corrected at each time by comparing the data obtained by accumulating the information, with the data of the change of the luminance over time or the data of the change of the luminance relative to the current amount, which are previously stored, and the video signals can be corrected such that in a deteriorated light emitting element, luminance equivalent to a light emitting element which is not deteriorated can be achieved. Therefore, uniformity of the screen can be maintained without bringing about nonuniformity of the luminance.
Further, after fabricating the panel, by grasping a dispersion of current flowing in the light emitting element of each pixel by measurement and correcting the video signal such that gray scale of each pixel is made uniform, a nonuniformity in the luminance among pixels which has been brought about before the deterioration is progressed can be restrained.
Further, except for detecting the light emitting period or the number of gray scale of the light emitting element, only presence or absence of light emittance of the light emitting element at a certain time point may be detected. Further, it is possible to estimate the degree of deterioration of the light emitting element from a rate of a number of times of emitting light as compared with a total number of times of detection by increasing a number of times of detecting presence or absence of emitting light.
Further, although in
In the case of the panel driven by using the analog video signal, by obtaining data including the amount of current flowing to the light emitting element of each pixel by sampling the video signal, the degree of deterioration of the light emitting element can be estimated based on the data.
Although as described over, an explanation has been given by taking an example of the light emitting element using OLED, the light emitting device of the invention is not limited to OLED but other light emitting element of PDP or FED may be used.
According to Embodiment 1, an explanation has been given with regard to an example of grasping the dispersion of the characteristics of the driving TFTs by using data of the current amount of each pixel and making the gray scales of pixels uniform. The current flowing in the light emitting element and the luminance are in a proportional relationship and therefore, the dispersion of the luminance of the light emitting element may be regarded, as the dispersion of flowing current. Therefore, the gray scale of each pixel can also be corrected by using data of the luminance of each pixel instead of data of the current amount of each pixel. According to the embodiment, an explanation will be given with regard to an example of making the gray scale of pixels uniform by using data of the luminance of pixels instead of data of the current amount of each pixel.
There are various methods of measuring the luminance of the light emitting element.
Data of luminance of each pixel is stored to a pixel characteristic correcting data storing portion. According to the embodiment, an ammeter for measuring current of each pixel is not needed. A video signal correcting circuit is provided with a function of grasping a dispersion in gray scale of each pixel by using data stored to the pixel characteristic correcting data storing portion and correcting a video signal such that gray scale of each pixel is made uniform.
The corrected video signal is converted into an analog signal in a D/A conversion circuit 4104 and supplied to a signal line drive circuit. By the corrected video signal, a dispersion in luminance among pixels caused by a dispersion of a characteristic in a driving TFT of each pixel can be reduced.
Specifically, a luminance constituting a reference is previously determined and the video signal is corrected such that a number of gray scale is increased for a pixel having a luminance higher than the luminance constituting a reference and increase the number of gray scale for a pixel having a luminance lower than the luminance constituting a reference.
The corrected video signal is supplied to a signal line drive circuit. A dispersion of luminance among pixels caused by a dispersion of characteristics of driving TFTs of pixels is reduced by the corrected video signal.
Specifically, a luminance constituting a reference is previously determined and the video signal is corrected such that a number of gray scale is reduced for a pixel having a luminance higher than the luminance and the number of gray scale is increased for a pixel having a luminance lower than the luminance.
Further, a designer can pertinently set by which luminance the video signals are corrected as the reference. For example, the reference may be constituted by an average value of luminance of all of pixels or a certain number of pixel selected irregularly, the reference may be determined by a highest or a lowest luminance or the reference may be determined by a luminance previously determined by calculation. A memory for storing data of luminance constituting the reference may separately be provided in accordance with which luminance constitutes the reference.
Further, the luminance may be measured by using a video signal having a specific one of gray scale as information or the luminance may be measured for each gray scale by using a video signal having a plurality or a total of respective gray scales as information. In the former case, in an arithmetic circuit, the video signal can be corrected by simply adding or reducing a determined number of gray scales in accordance with data of the luminance. Therefore, measurement of the luminance is further facilitated and a capacity of a memory used as the pixel characteristic correcting data storing portion can be reduced. Further, in the latter case, the relationship between the video signal and the luminance can be grasped further accurately and therefore, the gray scale of each pixel can be further uniformly.
In embodiment 1, both the voltage correcting circuit 118 and the video signal correcting circuit 119 compare data of the change over time of the luminance, data of the change of the luminance relative to the current amount, or the like, which are previously stored to the deterioration characteristic correcting data storing portion 117 with data obtained by accumulating the information with regard to the number of gray scale of each pixel stored to the nonvolatile memory for video signal 122 and grasp a degree of deterioration of each pixel.
An explanation with regard to a structure different from Embodiment 1 will be given in this Embodiment. In this Embodiment, in the video signal correcting circuit 119, video signals are corrected by the data with regard to the degree of deterioration of each pixel obtained in the voltage correcting circuit 118.
By the above structure, in the video signal correcting circuit 119, it is omitted to compare data of the change over time of the luminance, data of the change of the luminance relative to the current amount, or the like, which are previously stored to the deterioration characteristic correcting data storing portion 117 with data obtained by accumulating the information with regard to the number of gray scale of each pixel stored to the nonvolatile memory for video signal 122 and to grasp a degree of deterioration of each pixel, thereby to be able to improve the operation efficiency of the correcting circuit 100.
Examples of the invention will be described as follows.
According to the example, a flow of a production system of the invention will be explained. Further, there is a case in which a correcting circuit is fabricated to be included over a panel along with a pixel portion and there is a case of fabricating a separate correcting circuit over a separate substrate and mounting the correcting circuit over a panel thereafter.
Further, the data including the current values as information are not necessarily required to be values of current per se and may be information including a relative dispersion of current values among pixels in some form.
Further, when the characteristic correcting data has written to the volatile memory for pixels to some degree, the characteristic correcting data is written from the volatile memory for pixels to a correcting circuit. Specifically, the characteristic correcting data is written to a pixel characteristic correcting data storing portion formed from a nonvolatile memory inside the correcting circuit.
When the characteristic correcting data has completely been written to the pixel characteristic correcting data storing portion, the volatile memory for pixels is not needed. In case that the volatile memory keeps to be mounted thereafter, small-sized formation of the panel is hampered. Therefore, it is preferable to separate the volatile memory for pixels.
Meanwhile, when a material of an electroluminescent layer and a constitution of the layer of a light emitting element is determined, a data base of a characteristic of the light emitting element is formed. In the light emitting element, the electroluminescent materials used in the light emitting layers may differ depending on colors. When different electroluminescent materials are used or a structure of the electroluminescent layers differ, it is preferable to form a data base of characteristics of the light emitting elements for respective constitutions.
As the characteristic of a light emitting element, a value of luminance relative to a light emitting period (time) of the Light emitting element or a value of luminance relative to an amount of current flowing in the light emitting element can specifically be used. Further, the characteristics are not limited to the ones described over and any characteristic can be used so far as a reduction in luminance by deterioration of each pixel can be predicted by referring to a video signal.
Further, the data base of the characteristic of the light emitting element may be formed by a maker fabricating the panel or an existing data base may be acquired and used. The data with regard to the characteristics of the light emitting elements are stored to the correcting circuit as deterioration characteristic correcting data. Specifically, the data is stored to a deterioration characteristic correcting data storing portion formed from a nonvolatile memory provided to the correcting circuit.
Further, when the light emitting device is completed, the device is shipped as a product and is brought into a state of being able to be used by an end user. A flow until completed as the product is included in the production system of the invention.
When the light emitting device is used by the end user, the video signal is corrected in reference to the characteristic correcting data in the pixel characteristic correcting data storing portion and nonuniformity of luminance among pixels caused by the dispersion of the characteristics of the driving TFTs is always corrected.
Further, by monitoring the video signal, data capable of predicting the degree of deterioration, such as a light emitting period or a current value of the light emitting element at each pixel, are accumulated. Further, from the accumulated data to be able to predict the degree of deterioration and the deterioration characteristic correcting data in the deterioration characteristic correcting data storing portion, the degree of deterioration of the light emitting element of each pixel is predicted and the video signals are corrected such that nonuniformity of luminance among pixels caused by the dispersion in the deterioration of the light emitting elements are corrected.
Next,
Meanwhile, the correcting circuit is fabricated separately from the panel.
Further, when the characteristic correcting data has been written to the volatile memory for pixels to some degree, the characteristic correcting data are written from the volatile memory for pixels to the correcting circuit. Specifically, the data are written to the pixel characteristic correcting data storing portion formed using the nonvolatile memory inside the correcting circuit.
When the characteristic correcting data has been completely written to the pixel characteristic correcting data storing portion, the volatile memory for pixels is not needed, when the volatile memory keeps to be mounted thereafter, small-sized formation of the panel is hampered. Therefore, it is preferable to separate the volatile memory for pixels.
Meanwhile, the data base of the characteristics of the light emitting elements is formed. The database of the characteristics of the light emitting elements may be formed by a maker fabricating the panel or existing data base may be acquired and used. The data with regard to the characteristics of the light emitting elements are stored to the correcting circuit as the deterioration characteristic correcting data. Specifically, the data are stored to the deterioration characteristic correcting data storing portion formed using the nonvolatile memory provided to the correcting circuit.
Further, the correcting circuit is mounted to the panel. Further, the correcting circuit may be mounted to the panel before storing the deterioration characteristic correcting data or before storing the pixel characteristic correcting data.
Further, when the light emitting device is completed, the device is shipped as a product and is brought into a state of being able to be used by the end user. The flow until completing the device as the product is included in the production system of the invention.
Further, by separately fabricating the correcting circuit, the yield of the light emitting device can be increased. Further, by fabricating the correcting circuit so as to be included in the panel, the size of the light emitting device can be reduced.
In this example, description is made on a method for correcting a video signal which is adopted to a correction circuit of a light emitting device of the present invention.
In one approach to correct the decreased luminance of a deteriorated light emitting element on the basis of a video signal, a given correction value is added to an input video signal to convert the input signal to a signal practically representing a gray scale increased by several steps thereby achieving a luminance equivalent to that prior to the deterioration. The simplest way to implement this approach in circuit design is to provide a circuit in advance which is capable of processing data on an extra gray scale.
Specifically, in the case of a light emitting device adapted for 6-bit digital gray scales (64 gray scales) and including the deterioration correction function of the invention, for example, the device is so designed and manufactured as to have an additional capability of processing an extra 1 bit data for performing the correction and to practically process 7-bit digital gray scales (128 gray scales). Then, the device operates on the lower order 6-bit data in normal operation. When the deterioration of the light emitting element occurs, the correction value is added to the normal video signal and the aforesaid extra 1-bit is used for processing the signal of the added value. In this case, MSB (most significant bit) is used for the signal correction alone so that practically displayed gray scale includes 6 bits.
The present example can be freely implemented with being combined with Example 1.
In this example, description is made on a method for correcting the video signal in a different way from that of Example 2.
As use by the end user is repeated, degrees of deterioration of light emitting elements become different between the pixels, thereby occurring the luminance irregularities. This state is shown in
The greater the deterioration of the pixel, the greater the decrease of luminance of the pixel. Without the correction of luminance, the pixels, which are displaying a certain half tone, will encounter luminance variations as shown in
Next, actual correction operations are described. Measurement is previously taken to obtain a relation between the accumulative data on the light emitting periods or gray scales of the light emitting element and the decrease in the luminance thereof due to deterioration. It is noted that the accumulative data on the light emitting periods or gray scales and the decrease in the luminance of the light emitting element due to deterioration do not always present a monotonous relation. The degrees of deterioration of the light emitting element versus the accumulative data on the light emitting periods or gray scales are stored in the correction data storage portion in advance.
The voltage correction circuit 118 determines a correction value for the voltage supply from the voltage source 105 based on the data stored in the deterioration characteristic correcting data storing portion 117. The correction value for the voltage is determined based on the accumulative data on the light emitting periods or gray scales of a reference pixel. If the pixel 203 with the greatest deterioration is used as reference, for example, the pixel 203 is allowed to attain a desired gray scale but the pixels 201 and 202 are applied with excessive voltages so that a video signal therefore requires correction. Thus, the video signal correction circuit 119 so corrects the input video signal as to achieve the desired gray scales based on the degree of deterioration of the particular pixel having the greatest deterioration. Specifically, the accumulative data on the light emitting periods or gray scales are compared between the reference pixel and another pixel; a difference between the gray scales of these pixels is calculated; and the video signal is so corrected as to compensate for the gray scale difference.
The video signal correction circuit 119 decides a correction value for each video signal by comparing the input video signals with accumulative data on the light emitting periods or gray scales of each of the pixels.
In a case where the correction is performed using the pixel 203 as reference, for example, the pixels 201 and 202 differ from the pixel 203 in the degree of deterioration, thus requiring the correction of the gray scales by way of the video signal. It is expected from the accumulative data on the light emitting periods or gray scales of these pixels that the pixel 201 has a greater difference from the pixel 203 in the degree of deterioration than the pixel 202 does. Hence, the gray scale of the pixel 203 is corrected by a greater number of steps as compared with the correction for the pixel 202.
Now referring to
The individual bits of the 3-bit video signals correspond to three light emitting periods Ts1 to Ts3, respectively. The arrangement of the light emitting periods is expressed as Ts1:Ts2:Ts3=22:2:1. Although the example is explained by way of the example of the 3-bit video signal, the number of bits is not limited to this. In a case where an n-bit video signal is used, the ratio of the lengths of the light emitting periods is expressed as Ts1:Ts2: . . . :Ts (n−1):Tsn=2n-1:2n-2: . . . :2:1
The gray scale is determined by the sum of the lengths of the durations of light emissions appearing in one frame period. In a case where the light emitting elements are emitting light for all the light emitting periods, for example, the gray scale is at 7. Where the light emitting elements do not emit light for all the light emitting periods, the gray scale is at 0.
It is assumed that the voltage is corrected in order to permit the pixels 201, 202 and 203 to display a gray scale 3, but that the pixel 203 achieves the gray scale 3 whereas the pixel 201 displays a gray scale 5 and the pixel 202 displays a gray scale 4. In this case, the gray scale of the pixel 201 is higher by 2, whereas the gray scale of the pixel 202 is higher by 1.
Thus, the video signal correction circuit corrects the video signal to apply the pixel 201 with a corrected video signal of a gray scale 1 which is lower than the desired gray scale of 3 by 2, such that the light emitting element thereof may emit light only for the period of Ts3. On the other hand, the video signal correction circuit corrects the video signal to apply the pixel 202 with a corrected video signal of a gray scale 2 lower than the desired gray scale of 3 by 1, such that the light emitting element thereof emits light only for the period of Ts2.
Although this example illustrates the case where the correction is performed using the pixel with the greatest deterioration as reference, the invention is not limited to this. The designer may arbitrarily define the reference pixel and may arrange such that the video signal is corrected appropriately to accomplish coincidence of the gray scale with that of the reference pixel.
In a case where a pixel with the least deterioration is used as reference, the video signal is corrected based on the adding operation so that there is a disadvantage that the correction on the display of white is ineffective (Specifically, when “111111” is inputted as a 6-bit video signal, for example, any further adding operation cannot be done). On the other hand, in a case where a pixel with the greatest deterioration is used as reference, the video signal is corrected based on subtracting operation. In contrast to the correction based on adding operation, an ineffective range of correction is for the display of black and hence, there is little influence (Specifically, when “000000” is inputted as a 6-bit video signal, any further subtracting operation is not needed and an exact display of black can be accomplished by a normal light emitting element and a deteriorated light emitting element (simply by placing the light emitting elements in a non-emission state). The method has a feature that range gray scales higher than 0 by several steps neighboring black can be substantially adequately displayed if display data of a somewhat large number of bits are adapted to a display unit). Both the methods are useful for increasing the number of gray scales.
In an another effective approach, both the correction method, based on adding operation and the correction method based on subtracting operation are used in combination as switched at a given gray scale as boundary, for example, thereby compensating each other for the respective demerits thereof.
It should be note that it is possible to correct the gray scale by combining a correction of the light emitting period and a correction of amount of current flown in the light emitting element.
The present invention can be freely implemented by being combined with Example 1.
In Example 4, the following description refers to the configurations of a signal line drive circuit and a scanning line drive circuit provided for the light emitting device of the present invention.
The block diagram of a drive circuit in a light emitting device with respect to this example is shown in
A clock signal (CLK) and a start pulse (SP) are input to the shift register 602 in the signal line drive circuit 601. The shift register 602 generates timing signals in order based upon the clock signal (CLK) and the start pulse (SP), and supplies the timing signals one after another to the subsequent stage circuit through the buffer (not illustrated) and the like.
Note that, the timing signals output from the shift register circuit 602 may be buffer amplified by a buffer and the like. The load capacitance (parasitic capacitance) of a wiring to which the timing signals are supplied is large since many of the circuits or elements are connected to the wiring. The buffer is formed in order to prevent bluntness in the rise and fall of the timing signal, caused by the large load capacitance. In addition, the buffer is not necessarily provided.
The timing signal buffer amplified by a buffer is inputted to the latch A of 603. The latch A of 603 has a plurality of latch stages for processing corrected video signals in a correction circuit. The latch A 603 gradually reads in and maintains the corrected video signals input from the correction circuit, when the timing signal is input.
Note that the video signals may also be input in order to the plurality of latch stages of the latch A of 603 in reading in the video signals to the latch A of 603. However, the present invention is not limited to this structure. The plurality of latch stages of the latch A of 603 may be divided into a certain number of groups, and the video signals may be input to the respective groups at the same time in parallel, performing partitioned driving. Also, the number of the stages included in one group is referred to as dividing number. For example, when the latches are divided into groups by every four stages, it is referred to as partitioned driving with 4 divisions.
The period during which the video signals are completely written into all of the latch stages of the latch A of 603 is referred to as a line period. In practice, there are cases in which the line period includes the addition of a horizontal retrace period to the above-mentioned line period.
After one line period is completed, the latch signal is inputted to the latch B of 604. At the moment, the video signals written into and stored in the latch A of 603 are sent all together to be written into and stored in all stages of the latch B of 604.
After completing sending the digital video signal to the latch B of 604, it is performed to write the digital video signal into the latch A of 603 in accordance with the timing signal from the shift resister 602. In the second ordered one line period, the digital video signals that are written into and stored in the latch B of 604 are inputted to a signal line.
In place of a shift register, it is also practicable to utilize a different circuit such as a decoder circuit by which video signals are serially written to the latch circuits.
In the scanning line drive circuit 605, the timing signal from the shift register 606 is input to the buffer circuit 607 and successively input to a corresponding scanning line. A plurality of gates of those TFTs functioning as switching elements included in pixels corresponding one-line are connected to individual scanning lines. Since it is required to simultaneously turn ON a plurality of TFTs included in pixels corresponding to one line, the buffer circuit 607 is needed to be capable of flowing a large current.
In place of a shift register, it is also practicable to utilize a different circuit such as a decoder circuit to select gate signals and provide timing signals.
Next, a configuration of a signal line drive circuit for processing an analog video signal will be described.
A timing signal for controlling the timing for sampling a video signal is generated in the shift register 611 when a clock signal (CLK) and a start pulse signal (SP) are provided in the shift register 611. The generated timing signal is supplied to the level shifter 612. In the level shifter 612, amplitude of a voltage of the supplied timing signal, is amplified.
The timing signal amplified in the level shifter 612 is inputted in the sampling circuit 613. Then, the video signal corrected in the correction circuit is sampled synchronizing with the timing signal inputted in the sampling circuit 613 and is inputted in the pixel portion via the signal line.
The configuration of the drive circuit utilized in the present invention is not solely limited to the one shown in Example 4. The configuration based on this example may also be realized by being freely combined with Examples 1 to 3.
When a correcting circuit is formed over a substrate the same as that of a pixel portion, a signal line drive circuit and a scanning line drive circuit, low cost formation, compact formation and high speed drive can be realized by considerably reducing a number of parts. Meanwhile, when the correcting circuit is formed over a substrate different from that of the pixel portion, a video signal supplied to a light emitting device is corrected by the correcting circuit and thereafter inputted to the signal line drive circuit formed over a substrate the same as that of the pixel portion via FPC. By such method, there is achieved an advantage that there is compatibility by unitized formation of the correcting circuit and a general panel can be used as it is.
Further, although the layout over the substrate is not limited to the example of the drawing, it is preferable to arrange respective blocks to be proximate to each other in consideration of arrangement and wiring length of signal lines.
A video signal is inputted from an outside image source to a video signal correcting circuit inside the correcting circuit 407 via FPC 406. Thereafter, a corrected video signal is inputted to the signal line drive circuit 402.
Meanwhile, a voltage amount outputted from a voltage source is corrected at a voltage correcting circuit inside the correcting circuit. Further, although according to the embodiment, a height of voltage outputted from the voltage source provided to the correcting circuit is corrected by the voltage correcting circuit, the embodiment is not limited to the constitution. It is not necessarily needed to provide the voltage source for controlling the height of the voltage applied to the light emitting element inside the correcting circuit.
According to the example shown in
Next, an explanation will be given with regard to a constitution of the light emitting device of the invention when a correcting circuit separately formed is mounted to a panel by means of a wire bonding method, or COG (Chip On Glass) method.
A recessed portion 426 on a surface of the cover member 125 on the side facing to the substrate 420A is provided and hygroscopic substance or a substance capable of adsorbing oxygen is arranged therein.
A wiring led toward the substrate 420 (lead wiring) is connected to outside circuit or element of the light emitting device via FPC 427 by passing between the seal member 424 and the substrate 420.
The correcting circuit provided to the light emitting device of the invention is formed over a substrate (hereinafter, referred to as a chip) 428 different from the substrate 420, attached onto the substrate 420 by means of COG (Chip on Glass) method or the like and electrically connected to a power source line and a cathode (not illustrated) formed over the substrate 420.
By attaching the chip 428 formed with the correcting circuit onto the substrate 420 by the wire bonding method, COG method, or the like, the light emitting device can be constituted by one sheet of the substrate, the apparatus per se becomes compact and the mechanical strength is also increased.
Further, it can be carried out to connect the chip to the substrate by using a publicly-known method. Further, a circuit or an element other than the correcting circuit may be attached onto the substrate 420.
The example can be carried out with combined with Example 1 through Example 4.
In this example, a constitution of a pixel provided to a light emitting device of the invention will be explained in reference to a circuit diagram shown in
Further, the pixel 800 includes a switching TFT 803, a driving TFT 804, and erasing TFT 805, a storage capacitor 801 and a light emitting element 802. The gate of the switching TFT 803 is connected to the first scanning line Gaj. One of the source and the drain of the switching TFT 803 is connected to the signal line Si and the other thereof is connected to the gate of the driving TFT 804.
The gate of the erasing TFT 805 is connected to the second scanning line Gej. One of the source and the drain of the erasing TFT 805 is connected to the power source line Vi and the other thereof is connected to the gate of the driving TFT 804.
One of two electrodes provided to the storage capacitor 801 is connected to the power source line Vi and the other thereof is connected to the gate of the driving TFT 804. The storage capacitor 801 is provided to hold gate voltage of the driving TFT 804 when the switching TFT 803 is brought into a nonselected state (OFF state). Although the embodiment shows a constitution of providing the storage capacitor 801, the invention is not limited to the constitution and the storage capacitor 801 is not necessarily provided.
One of the source and the drain of the driving TFT 804 is connected to the power source line Vi and the other thereof is connected to a pixel electrode provided to the light emitting element 802.
The light emitting element 802 includes an anode and a cathode and an electroluminescent layer provided between the anode and the cathode. When the anode is connected to the source or the drain of the driving TFT 804, the anode constitutes the pixel electrode and the cathode constitutes a counter electrode. Conversely, when the cathode is connected to the source or the drain of the driving TFT 804, the cathode constitutes the pixel electrode and the anode constitutes the opposed electrode.
Voltage applied to the power source line Vi is corrected by a voltage correcting circuit provided to the correcting circuit. Further, the video signal inputted to the signal line S1 is corrected by a video signal correcting circuit provided to the correcting circuit.
Either of n-channel type TFTs and p-channel type TFTs can be used for the switching TFT 803, the driving TFT 804, or the erasing TFT 805. Further, the switching TFT 803, the driving TFT 804, or the erasing TFT 805 may be one other than a single gate structure, a multi gate structure of a double gate structure or a triple gate structure can be applied.
In the example, a constitution of a pixel provided to a light emitting device of the invention will be explained in reference to a circuit diagram shown in
Further, the pixel 900 includes a switching TFT 901, a driving TFT 902, a charge accumulating portion 903 including TFTs and capacitors, a storage capacitor 904 and a light emitting element 911.
The charge accumulating portion 903 is formed using a booster circuit using TFTs and capacitors and includes three n-channel type TFTs 905, 906, 910 and capacitors for booster circuit 907 and 908 in the example. Further, the booster circuit shown here is only an example and the example is not limited to the booster circuit.
In the example, power source voltage Vdd of the power source supply line V1 is supplied to both of the gate and the drain of the n-channel type TFT 906. Further, Vdd>Gnd. Further, both of the gate and the drain of the n-channel type TFT 905 are connected to the source of the n-channel type TFT 906. One of two electrodes for capacitor provided to the capacitor 908 is connected to the source of the n-channel type TFT 906 and the other thereof is supplied with a clock signal CLK. Further, one of two electrodes for capacitor provided to the capacitor 907 is connected to the source of the n-channel type TFT 905 and the other thereof is connected to Gnd. When the driving TFT 902 is made ON, voltage of the source of the n-channel type TFT 905 is provided to a pixel electrode of the light emitting element 911 via the n-channel type TFT 910 which is a switching element.
Assume that the clock signal is provided with two values of voltages of Vdd and Gnd. First, when the voltage of the clock signal is Gnd, one of the two electrodes of the capacitor 908 is applied with the voltage Vdd of the power source supply line and other thereof is applied with the voltage Gnd of the clock signal and charge C1 is accumulated.
Meanwhile, one of two electrodes of the capacitor 907 is applied with the voltage Vdd of the power source supply line and other thereof is applied with voltage Gnd of the clock signal and charge C2 is accumulated.
Next, when the voltage of the clock signal is elevated from Gnd to Vdd, a portion of charge of the capacitor 908 is accumulated in the capacitor 907 in accordance with law of conservation of charge. Further, when the driving TFT 902 is made ON by the video signal inputted via the switching TFT, charge accumulated in the capacitor 907 is provided to the light emitting element 911 via then-channel type TFT 910 which is the switching element. Further, the n-channel type TFT 910 provided in the charge accumulating portion 903 may be connected to control switching between the driving TFT 902 and the light emitting element 911.
In a state in which the electroluminescent layer of the light emitting element is not deteriorated at all, all of charge accumulated in the capacitor 907 is provided to the light emitting element. However, when the light emitting element is deteriorated, since the capacitor 907 is connected in parallel with the light emitting element 911, charge of amount of a threshold of the light emitting element increased by the deterioration is brought into a state of being accumulated and remaining in the capacitor 907.
Further, when the n-channel type TFT 910 is made OFF, and charge is accumulated again to the capacitor 907, charge of the amount of the threshold of the light emitting element increased by the deterioration is added to superpose. Therefore, charge provided from the capacitor 907 to the light emitting element can be maintained constant regardless of the deterioration of the light emitting element.
The example can be carried out with being combined with examples 1 through 6.
The light emitting device using the light emitting element is of the self-emission type, and thus exhibits more excellent visibility of the displayed image in a light place as compared to the liquid crystal display device. Furthermore, the light emitting device has a wider viewing angle. Accordingly, the light emitting device can be applied to a display portion in various electronic apparatuses.
Such electronic apparatuses using a light emitting device of the present invention include a video camera, a digital camera, a goggles-type display (head mount display), a navigation system, a sound reproduction device (a car audio equipment and an audio set), a lap-top computer, a game machine, a portable information terminal (a mobile computer, a mobile phone, a portable game machine, an electronic book, or the like), an image reproduction device including a recording medium (more specifically, an device which can reproduce a recording medium such as a digital versatile disc (DVD) and so forth, and includes a display for displaying the reproduced image), or the like. In particular, in the case of the portable information terminal, use of the light emitting device is preferable, since the portable information terminal that is likely to be viewed from a tilted direction is of ten required to have a wide viewing angle.
When the brighter luminance of light emitted from an electric field emission material becomes available in the future, the light emitting device in accordance with the present invention will be applicable to a front-type or rear-type projector in which light including output image information is enlarged by means of lenses or the like to be projected.
The aforementioned electronic apparatuses are more likely to be used for display information distributed through a telecommunication path such as Internet, a CATV (cable television system), and in particular likely to display moving picture information. The light emitting device is suitable for displaying moving pictures since the electric field emission material can exhibit high response speed.
A portion of the light emitting device that is emitting light consumes power, so it is desirable to display information in such a manner that the light emitting portion therein becomes as small as possible. Accordingly, when the light emitting device is applied to a display portion which mainly displays character information, e.g., a display portion of a portable information terminal, and more particular, a portable telephone or a sound, reproduction device, it is desirable to drive the light emitting device so that the character information is formed by a light emitting portion while a non-emission portion corresponds to the background.
As set forth over, the present invention can be applied variously to a wide range of electronic apparatuses in all fields. The electronic apparatuses in this example can be obtained by utilizing a light emitting device having the structure in which the structures in Example 1 through 7 are freely combined.
The invention can provide a light emitting device capable of restraining nonuniformity of luminance by a deterioration of an electroluminescent layer and a dispersion in TFT characteristics among pixels and capable of restraining a reduction in luminance of a total of a screen.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-120880 | Apr 2002 | JP | national |
| 2002-252826 | Aug 2002 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5247190 | Friend et al. | Sep 1993 | A |
| 5399502 | Friend et al. | Mar 1995 | A |
| 5793344 | Koyama | Aug 1998 | A |
| 6060840 | Foo et al. | May 2000 | A |
| 6188454 | Greene et al. | Feb 2001 | B1 |
| 6204610 | Komiya | Mar 2001 | B1 |
| 6229508 | Kane | May 2001 | B1 |
| 6246180 | Nishigaki | Jun 2001 | B1 |
| 6275061 | Tomita | Aug 2001 | B1 |
| 6317138 | Yano et al. | Nov 2001 | B1 |
| 6404139 | Saski et al. | Jun 2002 | B1 |
| 6476779 | Yano et al. | Nov 2002 | B1 |
| 6489938 | Ito | Dec 2002 | B1 |
| 6489952 | Tanaka et al. | Dec 2002 | B1 |
| 6498592 | Matthies | Dec 2002 | B1 |
| 6501227 | Koyama | Dec 2002 | B1 |
| 6501230 | Feldman | Dec 2002 | B1 |
| 6507227 | Genova et al. | Jan 2003 | B2 |
| 6512469 | Azami et al. | Jan 2003 | B1 |
| 6518962 | Kimura et al. | Feb 2003 | B2 |
| 6545653 | Takahara et al. | Apr 2003 | B1 |
| 6570611 | Satou et al. | May 2003 | B1 |
| 6587086 | Koyama | Jul 2003 | B1 |
| 6590581 | Koyama et al. | Jul 2003 | B1 |
| 6618030 | Kane et al. | Sep 2003 | B2 |
| 6628248 | Masumoto et al. | Sep 2003 | B2 |
| 6630840 | Tomita | Oct 2003 | B2 |
| 6635505 | Tanaka et al. | Oct 2003 | B2 |
| 6700330 | Koyama | Mar 2004 | B2 |
| 6710548 | Kimura | Mar 2004 | B2 |
| 6750792 | Azami et al. | Jun 2004 | B2 |
| 6753854 | Koyama et al. | Jun 2004 | B1 |
| 6774578 | Tanada | Aug 2004 | B2 |
| 6801180 | Matsueda | Oct 2004 | B2 |
| 6911781 | Yamazaki et al. | Jun 2005 | B2 |
| 7042427 | Inukai | May 2006 | B2 |
| 7049983 | Azami et al. | May 2006 | B2 |
| 7053874 | Koyama | May 2006 | B2 |
| 7088052 | Kimura | Aug 2006 | B2 |
| 7158157 | Yamazaki et al. | Jan 2007 | B2 |
| 7198967 | Tanaka et al. | Apr 2007 | B2 |
| 7227519 | Kawase et al. | Jun 2007 | B1 |
| 7362322 | Kimura et al. | Apr 2008 | B2 |
| 7456579 | Yamazaki et al. | Nov 2008 | B2 |
| 7586505 | Yamazaki et al. | Sep 2009 | B2 |
| 7683913 | Koyama et al. | Mar 2010 | B2 |
| 7863824 | Yamazaki et al. | Jan 2011 | B2 |
| 7986287 | Umezaki et al. | Jul 2011 | B2 |
| 8102126 | Yamazaki et al. | Jan 2012 | B2 |
| 8242699 | Yamazaki et al. | Aug 2012 | B2 |
| 20010020922 | Yamazaki et al. | Sep 2001 | A1 |
| 20010024186 | Kane et al. | Sep 2001 | A1 |
| 20020024481 | Kawabe et al. | Feb 2002 | A1 |
| 20020033783 | Koyama | Mar 2002 | A1 |
| 20020047550 | Tanada | Apr 2002 | A1 |
| 20020101395 | Inukai | Aug 2002 | A1 |
| 20020105279 | Kimura | Aug 2002 | A1 |
| 20030057895 | Kimura | Mar 2003 | A1 |
| 20060192699 | Azami et al. | Aug 2006 | A1 |
| 20070166860 | Tanaka et al. | Jul 2007 | A1 |
| Number | Date | Country |
|---|---|---|
| 0 905 673 | Mar 1999 | EP |
| 0 923 067 | Jun 1999 | EP |
| 1 003 151 | May 2000 | EP |
| 1 026 656 | Aug 2000 | EP |
| 1 128 439 | Aug 2001 | EP |
| 1 225 557 | Jul 2002 | EP |
| 1 310 938 | May 2003 | EP |
| 10-031449 | Feb 1998 | JP |
| 10-92576 | Apr 1998 | JP |
| 10-254410 | Sep 1998 | JP |
| 11-015437 | Jan 1999 | JP |
| 11-219146 | Aug 1999 | JP |
| 11-305722 | Nov 1999 | JP |
| 11-344949 | Dec 1999 | JP |
| 2000-066633 | Mar 2000 | JP |
| 2000-221942 | Aug 2000 | JP |
| 2000-267628 | Sep 2000 | JP |
| 2000-338920 | Dec 2000 | JP |
| 2000-347598 | Dec 2000 | JP |
| 2001-013908 | Jan 2001 | JP |
| 2001-022323 | Jan 2001 | JP |
| 2001-027891 | Jan 2001 | JP |
| 2001-134754 | May 2001 | JP |
| 2001-159878 | Jun 2001 | JP |
| 2001-184016 | Jul 2001 | JP |
| 2001-343933 | Dec 2001 | JP |
| 2001-350442 | Dec 2001 | JP |
| 2002-175041 | Jun 2002 | JP |
| 2003-177714 | Jun 2003 | JP |
| 2004-038210 | Feb 2004 | JP |
| WO 9013148 | Nov 1990 | WO |
| WO-0049636 | Aug 2000 | WO |
| WO-0077533 | Dec 2000 | WO |
| WO-0126085 | Apr 2001 | WO |
| Entry |
|---|
| Tsutsui et al., “Electroluminescence in Organic Thin Films”, Photochemical Processes in Organized Molecular Systems, 1991, pp. 437-450 (Elsevier Science Publishers, Tokyo, 1991). |
| M. A. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices”, Nature vol. 395, Sep. 10, 1998, pp. 151-154. |
| M. A. Baldo et al., “Very High-Efficiency Green Organic Light-Emitting Devices Based on Electrophosphorescence”, Applied Physics Letters vol. 75, No. 1, Jul. 5, 1999, pp. 4-6. |
| H. Shenk et al., “Polymers for Light-Emitting Diodes”, Euro Display Proceedings 1999, pp. 33-37. |
| Tsutsui et al., “High Quantum Efficiency in Organic Light-Emitting Devices with Iridium-Complex as Triplet Emissive Center”, Japanese Journal of Applied Physics vol. 38, Part 2, No. 12B, Dec. 15, 1999, pp. L1502-L1504. |
| Number | Date | Country | |
|---|---|---|---|
| 20120299987 A1 | Nov 2012 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10419824 | Apr 2003 | US |
| Child | 10923840 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13354672 | Jan 2012 | US |
| Child | 13570442 | US | |
| Parent | 12964838 | Dec 2010 | US |
| Child | 13354672 | US | |
| Parent | 12272825 | Nov 2008 | US |
| Child | 12964838 | US | |
| Parent | 10923840 | Aug 2004 | US |
| Child | 12272825 | US |
