KR100505342B1 - Apparatus for measuring life time of organic electroluminescence device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display system, and more particularly, to an apparatus for measuring the life of an organic electroluminescent device for measuring the life of an organic electroluminescent device (ORGANIC ELECTROLUMINESCENCE DEVICE).

To this end, according to the present invention, a plurality of device driving methods, that is, a constant current driving method, a constant voltage driving method, and a duty driving method, respectively, are measured according to the driving environment conditions. Intensity of the device is measured and displayed, and reliability is ensured by displaying the characteristic change of the device, e.g., voltage and current, over time in each device driving method. By varying the method or by the same driving method of the device and different driving environment, it is possible to observe the difference in lifespan and efficiency in each device driving method and to enable an accelerated experiment to accelerate the life prediction.

Description

Apparatus for measuring lifetime of organic electroluminescent device {APPARATUS FOR MEASURING LIFE TIME OF ORGANIC ELECTROLUMINESCENCE DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display system, and more particularly, to an apparatus for measuring the life of an organic electroluminescent device for measuring the life of an organic electroluminescent device (ORGANIC ELECTROLUMINESCENCE DEVICE).

With the development of the imaging industry, interest in the image information display system that transmits information to the brain through the eyes, which is one of the most sensory organs of human beings, has been greatly increased.

The image information display system is used for small and medium-sized displays, such as various letters, numbers, graphic terminals, scientific and medical monitors, display devices for receiving radar information, automobile dashboards, measuring instruments, and home A / V equipment. The devices employed in the system do not occupy space, require a wide viewing angle, can be viewed at close range, and require a low power consumption device that is lightweight and thin, and has a fast signal response speed.

As elements which meet the requirements of such a reduction in weight, flattening, and high image quality, liquid crystal displays (LCDs), plasma displays (PDPs), vacuum fluorescent displays (VFDs), electroluminescence (EL) display elements, and the like have been proposed.

Among the above devices, an electroluminescent display device emits a fluorescent compound by applying an electric field from the outside, and has excellent luminance, color contrast, viewing angle, response speed, and environmental resistance.

Such an electroluminescent display device is classified into an inorganic electroluminescent device and an organic electroluminescent device according to a material used, that is, an inorganic material or an organic material. In the case of an inorganic electroluminescent device, some of them are practically used, and recently, backlights of watches are also widely used. .

On the other hand, the organic electroluminescent device is an injection type which injects electrons and holes from the outside and generates a light emitting center by their recombination energy, and performs electroluminescence by direct current operation, and high luminance, that is, 100,000 ㏅ / m 2 is possible. It has a high efficiency, that is, 10 mA / W or more, and is superior to inorganic electroluminescent devices in terms of direct current low voltage driving, fast response (nsec), and multicoloring.

At this time, the above-mentioned organic electroluminescent element is operable even in alternating current, but emits only the bias of the injected side of the carrier.

In addition, the organic electroluminescent device has a characteristic in that the luminance of the device is gradually decreased with the use time or the voltage applied to the organic electroluminescent device is gradually increased with the use time.

That is, the light emitting device starts to drive, and the initial luminance decreases with time, and when it reaches a predetermined time, it decreases to half of the luminance at the start of driving. The lifetime of such a light emitting device is most important in the commercialization of the organic electroluminescent device.

However, in the related art, since there is no device for measuring the lifetime of such an organic electroluminescent device, an acceleration experiment for each organic electroluminescent device, that is, a driving environment condition for each of the organic electroluminescent device, for example, a vacuum state It was not possible to experiment to predict the service life by changing the driving environment such as temperature, temperature and so on.

The present invention has been made in view of the above, an object of the present invention is to display a change in driving characteristics according to the lifetime of the organic electroluminescent device and the device driving method, and to change the device driving method and the driving environment. The present invention provides an apparatus for measuring the lifespan of an organic electroluminescent device, which enables an accelerated experiment for predicting a change in lifespan, thereby ensuring reliability of the organic electroluminescent device.

The present invention for achieving the above object, an organic electroluminescent device for measuring the life time indicating the time taken to decrease to the luminance corresponding to half of the luminance at the start of driving with the passage of the drive time of the organic electroluminescent device An apparatus for measuring life of a device, the apparatus comprising: a driving power supply for supplying driving power corresponding to an element driving method selected by a measurer to measure the lifetime of the organic electroluminescent device among a plurality of device driving methods for driving the organic electroluminescent device; Way; Drive power measurement means for measuring and providing a current value and a voltage value of the drive power supplied from the drive power supply means; A device mounting part may be mounted to a plurality of organic electroluminescent devices, and the device mounted on the device mounting part may operate to correspond to a driving power supply and a driving operating environment according to each device driving method supplied from the driving power supply means. A chamber; Drive environment setting means for varyingly setting the drive operating environment of the chamber so as to correspond to the drive operating environment of the organic electroluminescent element set by the measurer; Luminance measuring means for measuring and providing a luminance indicating an intensity of light emitted by driving of an element mounted in an element mounting portion of the chamber; And a life measurement and display means for measuring the life and displaying the measured life by the voltage value and the current value provided by the drive power measurement means and the brightness provided by the brightness measurement means.

Hereinafter, with reference to the accompanying drawings will be described in detail the operation of the preferred embodiment according to the present invention.

1 is a block diagram showing the configuration of an apparatus for measuring life of an organic electroluminescent device according to the present invention, and includes a driving power supply unit 110, a driving power measurement unit 120, a chamber 130, and a driving environment setting unit 140. , The luminance measuring unit 150, the life measurement and the display unit 160.

At this time, the driving power measurement unit 120 is composed of a current measuring unit 121 and the voltage measuring unit 122, the life measurement and display unit 160 is an A / D converter (Analog to Digital Converter) (161) And a control unit 162, a storage unit 163, a clock generator 164, and a display unit 165.

Hereinafter, the operation of the life measuring device of the organic electroluminescent device according to the present invention configured as described above will be described in detail.

Reference numeral 140 is a driving environment setting unit 140, and is configured to be able to set the operating environment in the chamber (130) by the measurer.

That is, the driving environment setting unit 140 is configured to set the driving environment of the chamber 130 to correspond to the driving environment set by the measurer, so that the chamber 130 may operate in a vacuum environment and an inert gas environment. It is provided with a vacuum system and an inert gas purification system, and also has a temperature and humidity control system to control the temperature and humidity in the chamber 130.

At this time, the chamber 130 is capable of varying the driving operating environment by the driving environment setting unit 140 as described above, for example, is provided with an exhaust port to enable a vacuum and an inert gas environment. In addition, the chamber 130 may include a device mounting unit in which a plurality of organic electroluminescent devices may be mounted such that the plurality of organic electroluminescent devices may operate according to a plurality of device driving methods, that is, a constant current driving method, a constant voltage driving method, and a duty driving method. An element mounted on the element mounting unit 131 is driven in response to the driving power supplied from the driving power supply unit 110 to be described later and the operating environment set by the driving environment setting unit 140.

The driving power supply unit 110 is a device in which the driving power corresponding to the device driving method set by the measurer among the plurality of device driving methods for driving the organic electroluminescent device is mounted on the device mounting unit 131 of the chamber 130. Configured to supply.

That is, the method of driving the organic electroluminescent device includes a constant current driving method for applying a constant current to the device, a constant voltage driving method for supplying a constant voltage to the organic electroluminescent device, and a duty for supplying a constant current and a constant voltage according to waveform generation ( Duty) As a driving method, when the device driving method of any of the above-described device driving method is set by the measurer, the driving power supply unit 110 supplies the driving power corresponding to the set device driving method to the device mounting unit 131 in the chamber 130. Supply to the device mounted on. For example, when the constant current driving method is set by the measurer, the driving power supply unit 110 supplies a constant current corresponding to the constant current driving method to an element mounted in the element mounting unit 131 in the chamber 130, and by the measurer. When the constant voltage driving method is set, the driving power supply unit 110 supplies a predetermined voltage corresponding to the constant voltage driving method to the device mounted in the device mounting unit 131 in the chamber 130.

When the duty driving method is set, a predetermined current and a predetermined voltage are supplied to the device mounted in the device mounting unit 131 in the chamber 130 according to the waveform generated by the arbitrary waveform generator.

As described above, the driving power supply unit 110 supplies driving power corresponding to the device driving method set by the measurer to the device mounted in the device mounting unit 131 in the chamber 130.

The driving power measurement unit 120 measures the driving power, that is, the current value and the voltage value, supplied according to each of the plurality of device driving methods, and provides the measured power to the life measurement and display unit 160.

The driving power measuring unit 120 includes the current measuring unit 121 and the voltage measuring unit 122. In the case of the constant current driving method, the current measuring unit 121 is the driving power supplied from the driving power supply unit 110. That is, a constant current is supplied to the device mounted on the device mounting part 131 of the chamber 130, and the voltage measuring part 122 measures the voltage value applied to the device mounted on the device mounting part 131 to measure the lifetime. Provided by the display 160.

In the constant voltage driving method, the voltage measuring unit 122 supplies the driving power supplied from the driving power supply unit 110, that is, a predetermined voltage to the device mounted on the device mounting unit 131, and the current measuring unit 121 The current value supplied to the device is measured and provided to the life measurement and display unit 160.

In addition, in the case of the duty driving method, the current and the voltage are supplied to the device mounted in the device mounting unit 131 and measured and provided to the life measurement and display unit 160.

Meanwhile, as described above, the luminance measuring unit 150 operates the chamber 130 according to the operating environment set by the driving environment setting unit 140, and the element mounted on the element mounting unit 131 of the chamber 130 drives power. When driven by the driving power supplied from the supply unit 110, the luminance, which is the intensity of light according to the driving, is measured and provided to the lifetime measurement and display unit 160.

That is, the luminance measuring unit 150 measures the intensity of light according to the driving of the element mounted in the element mounting unit 131 of the chamber 130 and provides it to the life measurement and display unit 160. The detailed measurement process of 150 is omitted since it can be easily understood by those skilled in the art.

The luminance measured in this way is the luminous efficiency (e.g., the luminance per power over time). ) Can be obtained by the following equation.

In Equation 1, L is luminance, J is current density, and V is voltage.

At this time, in the preferred embodiment of the present invention, although the luminance measuring unit 150 is installed outside the chamber 130, those skilled in the art will readily understand that it may be installed inside the chamber 130.

And, as can be seen from the above life measurement and display unit 160, by measuring the current value and voltage value provided from the driving power measurement unit 120 and the luminance provided by the luminance measurement unit 150 and Indicates the measured lifetime.

In detail, the A / D converter 161 converts the analog current value and the voltage value provided from the driving power measurement unit 120 into digital values according to each device driving method, and provides them to the controller 162. In addition, the A / D converter 161 converts the analog luminance value measured by the luminance measuring unit 150 into a digital luminance value and provides the same to the controller 162.

The controller 162 controls to store the A / D-converted data in the storage unit 163, and the clock, ie, time, generated by the clock generator 164 to output luminance data among the A / D-converted data. The display unit 165 provides a display control signal for displaying on the screen a graph for indicating the change in luminance over time, so that the display unit 165 displays the luminance change graph on the screen under the control of the controller 162. Display.

2A and 2B are graphs showing a change in luminance and a change in voltage in a constant current driving method, and correspond to half of luminance at initial driving as time passes after the device is initially driven by the graph shown in FIG. 2A. It can know the life time which is the time to luminance.

In addition, the controller 162 displays a graph indicating a voltage change according to a clock generation of a voltage value converted into a digital value to display a voltage change in the constant current driving method as illustrated in FIG. 2B. The display unit 165 provides a display control signal for the display unit 165. Accordingly, the display unit 165 displays the voltage change graph on the screen under the control of the control unit 162, so that the change in the voltage in the constant current driving method can be known.

Although not shown in the drawings, the luminance change graph in the constant voltage driving method and the duty driving method is the same as the luminance change graph in the constant current driving method described above, and the constant voltage driving method shows a graph form in which current increases with time. The duty drive type represents a graph in which voltage and current change with time.

When the lifespan of the organic electroluminescent device is measured by the above operation process, the measurer may perform the acceleration experiment by changing the lifespan data of the measured device, the device driving method, and the driving environmental conditions.

That is, the lifetime of the organic electroluminescent device maintains an Arhennius curve shape as shown in FIG. 2A. The luminance change of the device, that is, the luminance change from the initial driving start, is determined by Equation 2. Can be.

In Equation 2 Represents the intensity of light over time, Is the intensity of light in the initial drive of the device, Is the decreasing factor, Indicates time.

At this time, the decrease factor Is represented by equation (3).

In Equation 3 Is the operating current, Is a constant, Is the temperature of the element mounted in the element mounting portion 131 of the chamber 130 is represented by the equation (4).

In Equation 4 Is the operating voltage, Indicates the ambient temperature.

Therefore, according to the above Equations 2 and 4, the lifespan of the device is changed by making the driving method (constant current driving method, constant voltage driving method, and duty driving method) of the device the same and different operating environment conditions (vacuum state and temperature condition). The change in driving characteristics of the device may be observed by setting the operating environment conditions to the same and setting the driving method of the device differently.

As described above, the life measurement apparatus of the organic electroluminescent device according to the present invention measures the life of the device by the change in brightness and driving characteristics with time and sets differently in a plurality of device driving methods and driving environment conditions By enabling accelerated experiments capable of predicting the change in the lifetime of the device, it is possible to ensure the reliability of the organic electroluminescent device.

1 is a block diagram showing the configuration of an apparatus for measuring life of an organic electroluminescent device according to the present invention;

2 is a graph showing changes in luminance, voltage, and current in each driving scheme of the organic electroluminescent device according to the present invention.

<Description of the symbols for the main parts of the drawings>

110: driving unit 120: driving power measurement unit

130: chamber 140: driving environment setting unit

150: luminance measuring unit 160: life measurement and display unit

Claims (3)

A lifespan measuring device of an organic electroluminescent device for measuring the life which represents the time taken to decrease to the luminance corresponding to half of the luminance at the start of driving with the passage of the driving time of the organic electroluminescent device, Drive power supply means for supplying a drive power corresponding to an element driving method selected by a measurer to measure the lifetime of the organic electroluminescent device among a plurality of device driving methods for driving the organic electroluminescent device; Drive power measurement means for measuring and providing a current value and a voltage value of the drive power supplied from the drive power supply means; A device mounting part may be mounted to a plurality of organic electroluminescent devices, and the device mounted on the device mounting part may operate to correspond to a driving power supply and a driving operating environment according to each device driving method supplied from the driving power supply means. A chamber; Drive environment setting means for varyingly setting the drive operating environment of the chamber so as to correspond to the drive operating environment of the organic electroluminescent element set by the measurer; Luminance measuring means for measuring and providing a luminance indicating an intensity of light emitted by driving of an element mounted in an element mounting portion of the chamber; Life time measuring apparatus of an organic electroluminescent element comprising life measuring and displaying means for measuring the life and displaying the measured life by the voltage value and current value provided by the driving power measuring means and the luminance provided by the brightness measuring means. . The method of claim 1, A plurality of organic light emitting device driving method set by the measurer, An organic electroluminescent device comprising any one of a constant current driving method for supplying a constant current, a constant voltage driving method for applying a constant voltage, and a duty driving method for supplying a constant current and a constant voltage according to an arbitrary waveform generation Life of the device. The method of claim 1, The life measurement and display means, An A / D converter for converting the current value and the voltage value provided from the driving power measuring unit and the luminance provided from the luminance measuring unit into corresponding digital values, respectively; In the device driving scheme and the luminance change graph which store the digital values provided by the A / D converter and change the digital values corresponding to the luminance provided by the A / D converter according to a clock generation. A control unit which controls to display a voltage and a current change graph indicating characteristics of a current and a voltage change in the screen; A storage unit which stores digital values corresponding to the current value, the voltage value, and the luminance according to the control of the controller; A clock generator for generating a clock over time with the controller; And a display unit for displaying the luminance change graph and the voltage and current change graph on a screen under the control of the controller.