OLED device having cooling system and driving method thereof

Abstract

The present invention relates to an OLED device having a cooling system and a driving method thereof. The OLED device according to an embodiment of the present invention comprises: an OLED; a cooling system including a cooling element for cooling the OLED; a temperature sensor for measuring the temperature of the OLED or an area adjacent to the OLED; and a control unit for controlling the driving of the OLED and the cooling system, wherein the control unit controls to drive the cooling system before driving the OLED, and to start driving the OLED when the temperature measured by the temperature sensor is less than or equal to a preset temperature.

Description

OLED device equipped with a cooling system and its driving method

[0001] The present invention relates to an OLED device and a driving method thereof. More specifically, the present invention relates to an OLED device and a driving method thereof, wherein the electrical and optical characteristics thereof are improved by using a cooling system.

[0002] Phototherapy is a treatment method that uses light of specific wavelengths to treat various medical conditions or alleviate symptoms.

[0003] Depending on the treatment purpose and target disease, ultraviolet (UV) light sources, visible light sources, infrared (IR) light sources, laser light sources, fluorescent lamps, LED light sources, and OLED light sources are used in phototherapy.

[0004] Among these, fluorescent lamps, LED light sources, and OLED light sources are relatively inexpensive and safe for the general public to use, so they can be usefully used in phototherapy devices used at home.

[0005] However, if the power is increased to obtain sufficient light output for phototherapy, side effects such as skin burns and tissue deformation may occur due to the high heat generated from the light source.

[0006] In addition, when using a light conversion film (for example, converting red light of a red OLED to near-infrared (NIR) light), the light output is reduced by 1 / 3 to 1 / 2, so it is necessary to increase the applied power to obtain sufficient light output. However, if the power applied to the light source is too high, there is a problem that the light source is damaged and a light extinction phenomenon occurs, which reduces the light output.

[0007] [Prior patent document] Korean Patent No. 10-2382643

[0008] An object of the present invention is to provide an OLED device having a cooling system and a method for driving the same.

[0009] Another object of the present invention is to provide an OLED device suitable for phototherapy and a method for driving the same.

[0010] Another object of the present invention is to provide an OLED device and a driving method thereof that can provide high light output even at a temperature lower than body temperature.

[0011] Another object of the present invention is to provide an OLED device and a driving method thereof in which temperature and light output increase constantly depending on input power.

[0012] Another object of the present invention is to provide an OLED device having flexibility and suitable for use in curved human body parts.

[0013] The above and other objects of the present invention can all be achieved by an OLED device equipped with a cooling system according to the present invention and a driving method thereof.

[0014] An OLED device according to one embodiment of the present invention includes an OLED, a cooling system including a cooling element for cooling the OLED, a temperature sensor for measuring a temperature of the OLED or an area adjacent to the OLED, and a control unit for controlling operation of the OLED and the cooling system.

[0015] The above control unit drives the cooling system before driving the OLED, and controls the OLED to start driving when the temperature measured by the temperature sensor is below a preset cooling temperature.

[0016] Additionally, the OLED is a flexible OLED, and the cooling system may be configured to include a plurality of cooling elements arranged spaced apart from each other, so that the OLED device according to one embodiment of the present invention may have flexibility.

[0017] An OLED device characterized in that the cooling element is a Peltier element, and the cooling system further includes a heat sink and a fan for dissipating heat generated from the cooling element.

[0018] In addition, the OLED includes one OLED unit element or a plurality of stacked OLED unit elements between a substrate positioned on the cooling element side and a substrate positioned on the light-emitting surface side, and the upper substrate may be a metal substrate or a substrate having a metal film layer.

[0019] Additionally, the cooling temperature may be a temperature that enables light having a saturated power density to be output without failure when the OLED is driven after being cooled to the cooling temperature.

[0020] Additionally, the cooling temperature may be a temperature that prevents the temperature measured by the temperature sensor from being heated to a temperature higher than body temperature or a protein denaturation temperature when the OLED outputs light having the saturation power density.

[0021] The above cooling temperature may be 5°C or lower or 0°C or lower.

[0022] The control unit applies power to the OLED within a preset maximum power range, wherein the maximum power may be a power at which the OLED outputs light having a saturated power density when applied to the OLED.

[0023] The above control unit can control to lower the power applied to the OLED or stop the operation of the OLED when the temperature measured by the temperature sensor is higher than the body temperature or protein denaturation temperature.

[0024] The above cooling temperature is -15°C to 0°C, and the control unit can control the temperature measured by the temperature sensor after the OLED is driven to be maintained in the range of 0°C to 5°C.

[0025] A method for driving an OLED device according to one embodiment of the present invention includes the steps of: driving a cooling system to cool the OLED; measuring the temperature of the OLED or an area adjacent to the OLED; and driving the OLED if the measured temperature is lower than a preset cooling temperature.

[0026] The above cooling temperature may be a temperature at which light having a saturated power density can be output without failure when the OLED is driven after being cooled to the above cooling temperature.

[0027] Additionally, the cooling temperature may be a temperature that prevents the temperature measured by the temperature sensor from being heated to a temperature higher than body temperature or protein denaturation temperature when the OLED outputs light having a saturated power density.

[0028] A method for driving an OLED device according to one embodiment of the present invention may further include a step of lowering power applied to the OLED or stopping driving the OLED when the temperature measured by the temperature sensor after driving the OLED is higher than body temperature or a protein denaturation temperature.

[0029] The above cooling temperature may be 5°C or lower or 0°C or lower.

[0030] In addition, a driving method of an OLED device according to one embodiment of the present invention may further include a step of controlling the cooling temperature to be -15°C to 0°C and the temperature measured by the temperature sensor after the OLED is driven to be maintained in a range of 0°C to 5°C.

[0031] The OLED device and its driving method according to the present invention can provide high light output even at low temperatures, thereby providing a high phototherapy effect without the risk of skin damage, and can also provide a good effect on itching.

[0032] In addition, the OLED device and its driving method according to the present invention can provide an effect in which the temperature and light output increase constantly as the input power increases, thereby allowing the user to easily control the desired temperature and light output.

[0033] In addition, the OLED device and its driving method according to the present invention have flexibility, thereby providing an effect that allows them to be used in close contact with a curved part of the human body.

[0034] In addition, the OLED device and its driving method according to the present invention can provide an effect of improving the light output efficiency of a fluorescent OLED.

[0035] FIG. 1 is a schematic diagram of an OLED device according to one embodiment of the present invention.

[0036] FIG. 2 is a schematic diagram of an OLED device according to another embodiment of the present invention.

[0037] Figure 3 is a flowchart of a method for driving an OLED device according to the present invention.

[0038] Figure 4 is a schematic diagram of an OLED device according to another embodiment of the present invention.

[0039] Figure 5 is a graph comparing the optical power density according to the temperature and power consumption of the OLED according to the applied power when the OLED of Example 1 is driven without a cooling system and when it is driven after being cooled to 0°C using a cooling system.

[0040] Figure 6 is a graph showing the illuminance according to the applied power and the illuminance according to the power consumption when the OLED of Example 1 is driven simultaneously with the cooling system.

[0041] Figure 7 is a graph showing the optical power density and OLED temperature according to the applied power, and the optical power density and OLED temperature according to the power consumption when the OLED of Example 1 was driven without cooling and after being cooled to 0°C, 5°C, 10°C, 15°C, and 20°C using a cooling system.

[0042] Figure 8 is a graph showing the optical power density and OLED temperature according to the applied power, and the optical power density and OLED temperature according to the power consumption when the OLED of Example 2 was driven without cooling and after being cooled to 0°C, 5°C, 10°C, 15°C, and 20°C using a cooling system.

[0043] Figure 9 is a graph showing the optical power density and OLED temperature according to the applied power, and the optical power density and OLED temperature according to the power consumption when the OLED of Example 3 was driven without cooling and after cooling to 0°C, 5°C, 10°C, 15°C, and 20°C using a cooling system.

[0044] FIG. 10 is a graph showing the change rate of illuminance and current when an OLED device according to one embodiment of the present invention is continuously driven for 70 minutes and continuously driven for 12 hours while maintaining the applied power so that the saturation power density is output.

[0045] Hereinafter, an OLED device equipped with a cooling system according to the present invention and a driving method thereof will be described in detail with reference to the attached drawings.

[0046] In the following description, only the parts necessary for understanding the OLED device having a cooling system according to an embodiment of the present invention and the driving method thereof are described, and the description of other parts may be omitted so as not to distract from the gist of the present invention.

[0047] In addition, the terms or words used in the present specification and claims described below should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention so as to most appropriately express the present invention.

[0048] Throughout the specification, when a part is said to "include" a component, this does not exclude other components, but rather implies the inclusion of other components, unless otherwise specifically stated. Furthermore, terms such as "part," "unit," and "module" used in the specification mean a unit that processes at least one function or operation, which may be implemented using hardware, software, or a combination of hardware and software.

[0049] In various embodiments, components having the same configuration are described representatively in one embodiment using the same symbols, and in other embodiments, components having different configurations from one embodiment are described.

[0050] FIG. 1 is a schematic diagram of an OLED device according to one embodiment of the present invention.

[0051] As illustrated in FIG. 1, an OLED device (100) according to one embodiment of the present invention includes an OLED (10), a cooling system (20), a temperature sensor (30), and a control unit (40).

[0052] The OLED (10) may be any type of OLED that provides light, such as a red OLED that emits red light, a yellow OLED that emits yellow light, a green OLED that emits green light, a blue OLED that emits blue light, a phosphorescent OLED, or a fluorescent OLED, as a light source of the OLED device (100) according to one embodiment of the present invention.

[0053] In addition, the OLED device (100) according to one embodiment of the present invention may be, for example, a phototherapy device, and in this case, the OLED (10) may be an OLED that provides light of a wavelength required for phototherapy.

[0054] The OLED (10) may be configured to include one or more OLED unit elements between the upper substrate and the lower substrate. In this case, a plurality of OLED unit elements may be arranged in a plane, or a plurality of OLED unit elements may be stacked in a tandem structure between the upper substrate and the lower substrate for higher light output.

[0055] In addition, it is preferable that the upper substrate located on the cooling element side of the OLED (10) be a metal substrate or a plastic substrate having a metal film layer so that it can be efficiently cooled by the cooling system described later.

[0056] Additionally, the OLED (10) may include a light conversion film (e.g., a film that converts emitted light into near-infrared light, etc.).

[0057] The cooling system (20) is a system for cooling the OLED (10).

[0058] A cooling system is a system that can cool the OLED when it is not generating heat beyond dissipating the heat generated when the OLED is in operation.

[0059] The cooling system is a system for cooling an OLED at room temperature before operation to a temperature lower than room temperature, specifically, 5°C or more lower than room temperature, preferably to a temperature of 5°C or lower (0°C to 5°C, -15°C to 5°C), more preferably to a temperature lower than 0°C (around 0°C, -15°C to 0°C). Accordingly, the cooling system includes a cooling element such as a Peltier element.

[0060] At this time, the cooling performance may vary depending on the packaging material of the Peltier element, such as ceramic, metal, or plastic, so the packaging material of the Peltier element can be selected and configured according to the desired cooling performance.

[0061] Additionally, the cooling system may further include a heat sink and a fan to dissipate heat generated from the cooling element.

[0062] The temperature sensor (30) is a sensor for measuring the temperature of the OLED or the temperature of an area adjacent to the OLED.

[0063] The temperature sensor provides the measured temperature value to the control unit, which will be described later, so that the control unit can control the operation of the OLED (10) according to the measured temperature value.

[0064] The temperature of the OLED measured by the temperature sensor may be the temperature of the OLED surface. Alternatively, the temperature of the area adjacent to the OLED may be the temperature of an area so close to the OLED that the temperature of that area can be considered the temperature of the OLED, or the temperature of the OLED can be estimated from the temperature of that area. In one embodiment of the present invention, the OLED device may be a phototherapy device, and the area adjacent to the OLED may be the area between the OLED and the skin to which the OLED's light is irradiated.

[0065] Meanwhile, the temperature measured on the surface of the OLED directly exposed to the outside and the area between the OLED and the skin may be higher than the actual OLED temperature due to external influences. Therefore, as illustrated in FIG. 2, a temperature sensor (31) capable of measuring the temperature of the OLED surface or cooling element that is not directly exposed to the outside may be added, and the temperature of the OLED may be adjusted to a desired temperature by additionally considering the temperature measured by the temperature sensor (31).

[0066] The control unit (40) controls the operation of the OLED (10) and the cooling system (20).

[0067] Specifically, the control unit drives the OLED and the cooling system (20) so that the OLED (10) operates together when the OLED (10) operates.

[0068] More preferably, the control unit (40) drives the cooling system (20) before driving the OLED (10). Then, when the temperature of the OLED or an area adjacent to the OLED measured by the temperature sensor (30) falls below a preset cooling temperature, the OLED is driven.

[0069] Typically, increasing the power applied to an OLED will damage the OLED before it can output light with a saturation power density. Conversely, cooling the OLED to an appropriate temperature before driving it allows the light output to increase until it reaches the saturation power density without causing damage. Here, the saturation power density refers to the maximum power density at which the OLED no longer increases with increasing power applied.

[0070] Additionally, the higher the power applied to an OLED, the higher its temperature typically is. Conversely, if the OLED is cooled to an appropriate temperature before being powered, its temperature will not rise above the protein denaturation temperature (e.g., 40 to 42°C or higher) or body temperature (e.g., 36 to 37.5°C), even if the OLED outputs light at saturation power density.

[0071] Therefore, the control unit (40) controls the OLED (10) to be driven after it has been cooled to a cooling temperature at which the OLED can output light having a saturated power density without damage, or more preferably, a cooling temperature at which the temperature of the OLED does not rise to a temperature higher than the protein denaturation temperature or body temperature even when the applied power is increased to output light having a saturated power density.

[0072] In an OLED device according to one embodiment of the present invention, the preset cooling temperature is a temperature 5°C or more lower than room temperature, preferably 5°C or less, 0°C to 5°C, or -15°C to 5°C, more preferably around 0°C or 0°C or less (-15°C to 0°C).

[0073] Additionally, the control unit (40) can control power to be applied to the OLED within a preset maximum power range. Here, the maximum power is the power at which light having a saturated power density is output from the OLED when applied to the OLED.

[0074] Furthermore, if the OLED is cooled to an appropriate temperature before being driven, even if the OLED outputs light with a saturated power density, the OLED will not rise to a temperature higher than a temperature at which protein denaturation may occur (e.g., 40°C to 42°C) or body temperature (e.g., 36°C to 37.5°C). Therefore, the OLED device according to one embodiment of the present invention can be preferably used as a phototherapy device.

[0075] Meanwhile, the temperature of the OLED may rise to a temperature at which protein denaturation may occur due to internal or external factors. The control unit (40) may control the power applied to the OLED to be reduced or the operation of the OLED to be stopped until the temperature is lowered when the temperature measured by the temperature sensor (30, 31) reaches a preset maximum temperature (e.g., a temperature at which protein denaturation may occur).

[0076] In addition, when the temperature of the OLED does not exceed 20°C during operation of the OLED, more preferably, when the temperature of the OLED is between 0°C and 5°C, the temperature of the skin located near the OLED can be cooled to between 10°C and 15°C, which is effective in improving skin itching. Therefore, when improvement of skin itching is required, the control unit can control the operation of the OLED so that the temperature measured by the temperature sensor (30, 31) becomes a preset temperature for improving skin itching (20°C or less, more preferably between 0°C and 5°C).

[0077] A method for driving an OLED device according to one embodiment of the present invention will be described again with reference to FIG. 3 as follows.

[0078] When the operation of the OLED device according to one embodiment of the present invention begins, the control unit (40) operates the cooling system (20) to cool the OLED (10) (S10).

[0079] Through cooling in step S10, the OLED (10) at room temperature (e.g., 25°C) is cooled to a temperature lower than room temperature.

[0080] At this time, the temperature sensor (30) measures the temperature of the OLED or an area adjacent to the OLED (S20).

[0081] The temperature measured in step S20 is transmitted to the control unit (40). The temperature sensor (30) can periodically measure the temperature of the OLED or an area adjacent to the OLED and transmit the measured temperature to the control unit.

[0082] The control unit (40) determines whether the temperature measured from the temperature sensor is below the preset cooling temperature, and drives the OLED if the measured temperature is below the preset cooling temperature (S30).

[0083] Here, the preset cooling temperature is the temperature at which the OLED can output light with a saturated power density without failure when driven after cooling to the cooling temperature. Furthermore, the cooling temperature is the temperature at which the OLED does not heat to a temperature higher than body temperature or protein denaturation temperature when outputting light with a saturated power density, as measured by a temperature sensor. The preset cooling temperature with such characteristics may be, for example, 5°C or lower, more preferably 0°C.

[0084] In addition, when the OLED device according to one embodiment of the present invention is a phototherapy device, it is desirable to enable light having a sufficient power density required for phototherapy to be output, especially when the OLED has a light conversion film.

[0085] Therefore, the control unit (40) can increase the applied power within the maximum power range in which the OLED outputs light having a saturated power density when driving the OLED.

[0086] Meanwhile, when the OLED device according to one embodiment of the present invention is a phototherapy device, it is preferable that the temperature measured by the temperature sensor (30) does not rise above a preset maximum temperature even when the control unit (40) applies maximum power to the OLED. Here, the maximum temperature may be a temperature at which protein denaturation may occur (e.g., 40°C to 42°C) or body temperature (e.g., 36°C to 37.5°C).

[0087] Therefore, it is desirable to determine the cooling temperature in step S30 as a temperature that prevents the temperature of the OLED from rising above the protein denaturation temperature or body temperature even when the OLED reaches the saturation power density; nevertheless, if the temperature measured by the temperature sensor reaches a preset maximum temperature, the control unit lowers the power applied to the OLED or controls the operation of the OLED to be stopped.

[0088] In addition, to improve skin itching, the OLED is driven and then the control unit controls the temperature measured by the temperature sensor to be maintained within a preset temperature range for improving skin itching (20°C or less, more preferably 0°C to 5°C), and when the preset temperature range is exceeded, the power applied to the OLED is lowered or the driving of the OLED is controlled to be stopped.

[0089] The OLED device (100) and its driving method according to one embodiment of the present invention described so far can improve the electrical and optical characteristics of the OLED by driving the cooling system (20) before the control unit (40) drives the OLED (10) to cool the OLED to a preset cooling temperature or lower and then driving the OLED.

[0090] The OLED device according to one embodiment of the present invention may be a phototherapy device, and the phototherapy device is preferably positioned close to the skin requiring treatment.

[0091] Accordingly, it is preferable that the OLED device (100) according to one embodiment of the present invention be configured to have flexibility so as to be able to bend according to the curve of the skin, such as the abdomen, as shown in FIG. 4.

[0092] Specifically, it is preferable to use a flexible OLED as the OLED (10) to provide flexibility to the OLED device, and to configure the OLED device (100) to have flexibility as a whole by arranging a plurality of small cooling elements (21) that do not have flexibility at regular intervals on the top of the OLED (10) as shown in FIG. 4.

[0093] Meanwhile, when a phototherapy device is placed in close contact with the skin, skin damage (protein denaturation) may occur due to the heat generated by the light source. However, the OLED device according to one embodiment of the present invention is safe because the OLED is cooled to a low temperature before being powered up, and even after being powered up, the OLED temperature does not rise above a temperature (40°C) that could cause protein denaturation.

[0094] Furthermore, even when sufficient light for phototherapy is output, the temperature of the OLED device (100) according to one embodiment of the present invention is maintained lower than the skin temperature, thereby improving skin itching of the affected area in direct contact with the OLED device.

[0095] In addition, considering the improved skin cooling function for improving skin itching, it is desirable to control the temperature of the OLED so that it does not exceed 20℃ when the OLED is driven, and if the temperature of the OLED is controlled to be 0℃ to 5℃, the skin can be sufficiently locally cooled to about 10℃ to 15℃, which is more desirable.

[0096] In order to confirm the effectiveness of the OLED device and its driving method according to one embodiment of the present invention, its stability as a phototherapy device, and the desirable cooling temperature of the OLED, the following tests were conducted.

[0097] [Test 1]

[0098] As the OLED of Example 1, an OLED with the following characteristics was used.

[0099] - Phosphorescent OLED (red OLED: ROLED)

[0100] - Glass / glass substrate

[0101] - A single-layer structure with one OLED unit located between the substrates.

[0102] The OLED of Example 1 was cooled to 0℃ and then driven, and the temperature of the OLED and the power density of the irradiance were measured while increasing the applied power.

[0103] As comparative example 1, the same OLED as in example 1 was measured at room temperature (25°C) without cooling, while increasing the applied power, and the temperature and light power density of the OLED were measured.

[0104] As a result, as shown in Fig. 5, in the case of the OLED of Example 1, as the applied power increases, the power density and temperature increase linearly, reaching 72.2 mW / cm 2 It showed a saturation power density of , and the temperature of the OLED did not exceed 40℃, which is the safe temperature for skin treatment (protein denaturation temperature) until the saturation power density was reached.

[0105] On the other hand, in the case of comparative example 1, the saturated power density was 72.2 mW / cm 2 Lower power density 43mW / cm 2 After reaching , the OLED was damaged, and the output power, power density, and temperature all decreased regardless of the applied voltage and current.

[0106] Also, the saturation power density of Example 1 was 72.2 mW / cm 2 Lower power density 43mW / cm 2 When it reached , the temperature had already exceeded 40℃, which is the safe temperature for skin treatment.

[0107] Through this test 1, it can be confirmed that the OLED device according to one embodiment of the present invention not only has stability as a phototherapy device, but also has excellent electrical and optical characteristics.

[0108] In addition, unlike Comparative Example 1, Example 1 shows that the temperature and power density (illuminance) of the OLED increase linearly as the input power increases, so that the user can easily adjust the treatment temperature and illuminance required by adjusting the input power.

[0109] [Test 2]

[0110] As comparative example 2, the OLED of example 1 was operated simultaneously with the cooling system at room temperature (25°C) without cooling.

[0111] The optical power density (illuminance) was measured while increasing the applied power, and the optical power density according to the increase in power consumption was also measured.

[0112] As a result, as shown in Fig. 6, the power consumption is 4.75 W and 45 mW / cm 2 After indicating the power density, it was confirmed that the light extinction phenomenon, in which the illuminance and light power density decreased even when a larger power was applied, was observed.

[0113] This comparative example 2 had a slightly higher maximum power density than comparative example 1, which did not use a cooling system, but was 72.2 mW / cm. 2 Compared to Example 1, which showed the saturation power density, it can be confirmed that the electrical and optical characteristics of the OLED are further improved when the OLED is driven after cooling the OLED with the cooling system, even when the cooling system and the OLED are driven together. This indicates that, although a light quenching phenomenon due to heat generation generally occurs when excessive power is input to a photodiode, when the OLED is cooled using a cooling system and then driven, the light output can continuously increase as the excessive power increases due to the combination of the OLED light-emitting layers.

[0114] [Test 3]

[0115] The OLED of Example 1 was cooled to 0℃, 5℃, 10℃, 15℃, and 20℃, respectively, and the temperature and power density of the OLED were measured while increasing the applied power (i.e., the starting temperatures for driving the OLED were 0℃, 5℃, 10℃, 15℃, and 20℃).

[0116] As a result, as shown in Fig. 7, it can be confirmed that the temperature and power density (illuminance) of the OLED increase linearly with increasing applied power at all cooling temperatures. However, when the starting temperature was set to 10°C, 15°C, and 20°C, the temperature of the OLED exceeded 40°C when the saturated power density was reached.

[0117] Therefore, when the OLED device according to one embodiment of the present invention is a phototherapy device and an OLED such as Example 1 is used, it is preferable to set the cooling temperature to 5°C or lower.

[0118] Furthermore, even if the OLED of Example 1 is cooled to 0℃, 5℃, and 10℃ and then driven so that the temperature of the OLED does not exceed 20℃, the power is about 40mW / cm 2 50mW / cm 2 Light having a power density of was output. Therefore, it can be confirmed that the OLED device according to one embodiment of the present invention can improve skin itching simultaneously with phototherapy.

[0119] Furthermore, when the cooling temperature is lowered below 0°C (specifically, -15°C to 0°C), light having sufficient power density can be output even when the OLED is driven at 0°C to 5°C, which is more desirable for improving skin itching.

[0120] [Test 4]

[0121] As the OLED of Example 2, an OLED with the following characteristics was used.

[0122] - Phosphorescent OLED (red OLED: ROLED)

[0123] - Metal / glass substrate (the substrate on the cooling system side is metal)

[0124] - A tandem structure with two OLED unit elements stacked between substrates.

[0125] Using the OLED of Example 2, the OLED was cooled to 0℃, 5℃, 10℃, 15℃, and 20℃, respectively, in the same manner as in Test 3, and the temperature and power density of the OLED and the irradiance were measured while increasing the applied power.

[0126] As a result, as shown in Fig. 8, the temperature and power density (illuminance) of the OLED increased linearly with increasing applied power at all cooling temperatures, and a higher saturation power density (281 mW / cm) was achieved than when the OLED of Example 1 was used. 2 ) values ​​were measured.

[0127] This is believed to be the result of using a tandem structure OLED that can output light with a high power density, while also using a metal substrate, which allows for applying more power without overheating the OLED.

[0128] Additionally, compared to the OLED of Example 1, the OLED of Example 2 output light with a higher saturation power density, but the temperature of the OLED was maintained lower.

[0129] Therefore, when high illuminance (light power density) is required, it is preferable to use a metal / glass substrate OLED rather than a glass / glass substrate OLED.

[0130] Additionally, OLEDs equipped with a metal film layer that can improve heat transfer on a plastic substrate or the like can be used instead of a metal substrate.

[0131] In this regard, it can also be seen that users can control the electrical and optical properties of the OLED by selecting any one of the OLED encapsulation types, such as glass / glass, glass / metal, metal / plastic, plastic / plastic, etc.

[0132] Meanwhile, when the OLED of Example 2 was cooled to 0°C and 5°C, the temperature of the OLED did not exceed body temperature when the saturated power density was reached.

[0133] In addition, even when the OLED is driven so that its temperature does not exceed 20℃, light with a power density sufficient for phototherapy is output.

[0134] Therefore, when the OLED device according to one embodiment of the present invention is a phototherapy device and the OLED of Example 2 is used, the cooling temperature is preferably 5°C or lower. In this case, even if the saturation power density is reached, not only is a temperature lower than body temperature maintained, but even when driven so as not to exceed 20°C, light having a power density sufficient for phototherapy is output, making it effective in treating skin itching.

[0135] Furthermore, when considering the skin that will be adjacent to the OLED (10), it is preferable that the preset temperature range for starting the OLED operation be -15°C or higher and 5°C or lower, and when the cooling temperature is set to -15°C or higher and 0°C or lower, light with sufficient power density can be output even if the OLED is operated at 0°C to 5°C so that it does not exceed 5°C.

[0136] [Test 5]

[0137] As the OLED of Example 3, an OLED with the following characteristics was used.

[0138] - Fluorescent blue OLED (BOLED)

[0139] - Metal / glass substrate

[0140] - A tandem structure with two OLED unit elements stacked between substrates.

[0141] The OLED of Example 3 was cooled to 0℃, 5℃, 10℃, 15℃, and 20℃, respectively, and the temperature and light power density of the OLED and irradiance were measured while increasing the applied power.

[0142] As comparative example 3, the same OLED as in example 3 was measured at room temperature (25°C) without cooling, while increasing the applied power, and the temperature and light power density of the OLED were measured.

[0143] As a result, as shown in Fig. 9, in the case of comparative example 3, the power density was 142.96 mW / cm 2 After reaching , the OLED was damaged, and the output power, power density, and temperature all decreased regardless of the applied voltage and current. In addition, the temperature of the OLED was 56.8℃, which was well over 40℃ at the highest power density.

[0144] In contrast, the OLED of Example 3 had an emission of 230 mW / cm at all starting temperatures. 2 It can be seen that the temperature and power density (illuminance) of the OLED increase linearly with increasing applied power until the saturation power density is reached.

[0145] In particular, it can be confirmed that the OLED of Example 3, although a fluorescent OLED, can increase the luminous efficiency by providing a cooling system and operating after cooling as in the present invention.

[0146] That is, it can be seen that the present invention is very effective in increasing the light conversion efficiency of fluorescent OLEDs, which have an efficiency of about 25%, compared to phosphorescent OLEDs, which have an efficiency of nearly 100% in converting electrical energy into light.

[0147] [Test 6]

[0148] The OLED of Example 1 was operated continuously for a total of 70 minutes with the light irradiance and current changed every 10 minutes while maintaining the applied power so that the saturation power density was output, and the rate of change was measured.

[0149] In addition, the OLED of Example 1 was operated continuously for 12 hours while maintaining the applied power so as to output saturated power density, and the change rate of illuminance and current was measured.

[0150] As a result, as shown in Fig. 10, during continuous operation for 70 minutes, the change in relative current was between 97.8 and 100%, and the relative illuminance was between 96.2 and 100%. During continuous operation for 12 hours, the relative illuminance was between 97.3 and 105.8%, and the relative current was confirmed to be stable within the range of 91 and 93.3%.

[0151] These tests confirm that the OLED device according to one embodiment of the present invention maintains stable electrical and optical characteristics even during long-term continuous operation.

[0152] The OLED device equipped with a cooling system according to the present invention and its driving method have been described with reference to specific examples. However, it should be understood that the present invention is not limited to these specific examples, and various changes and modifications may be made without departing from the spirit and scope of the invention as claimed in the claims.

Claims

1. OLED(10); A cooling system (20) including a cooling element (21) for cooling the OLED (10); A temperature sensor (30, 31) that measures the temperature of the OLED or an area adjacent to the OLED; and A control unit (40) that controls the operation of the OLED and the cooling system; An OLED device characterized in that the control unit (40) drives the cooling system before driving the OLED and controls the OLED to start driving when the temperature measured by the temperature sensor is below a preset cooling temperature.

2. In paragraph 1, An OLED device characterized in that the above OLED (10) is a flexible OLED, and the cooling system (20) includes a plurality of cooling elements arranged spaced apart from each other.

3. In paragraph 1 or 2, An OLED device characterized in that the cooling element (21) is a Peltier element, and the cooling system further includes a heat sink and a fan for dissipating heat generated from the cooling element.

4. In any one of paragraphs 1 to 3, An OLED device characterized in that the OLED (10) includes one OLED unit element or a plurality of stacked OLED unit elements between a substrate positioned on the cooling element side and a substrate positioned on the light-emitting surface side, and the upper substrate is a metal substrate or a substrate having a metal film layer.

5. In any one of paragraphs 1 to 4, An OLED device characterized in that the above cooling temperature is a temperature at which light having a saturated power density can be output without failure when the OLED (10) is driven after being cooled to the above cooling temperature.

6. In any one of paragraphs 1 to 5, An OLED device characterized in that the above cooling temperature is a temperature that prevents the temperature measured by the temperature sensor from being heated to a temperature higher than body temperature or protein denaturation temperature when the OLED (10) outputs light having the saturation power density.

7. In any one of paragraphs 1 to 6, An OLED device characterized in that the cooling temperature is 5°C or lower or 0°C or lower.

8. In any one of paragraphs 1 to 7, An OLED device characterized in that the control unit (40) applies power to the OLED within a preset maximum power range, and the maximum power is a power at which the OLED outputs light having a saturated power density when applied to the OLED.

9. In any one of paragraphs 1 to 8, An OLED device characterized in that the control unit (40) controls the power applied to the OLED to be lowered or the operation of the OLED to be stopped when the temperature measured by the temperature sensor is higher than body temperature or protein denaturation temperature.

10. In any one of paragraphs 1 to 9, An OLED device characterized in that the cooling temperature is -15°C to 0°C, and the control unit (40) controls the temperature measured by the temperature sensor (30, 31) after the OLED (10) is driven to be maintained in the range of 0°C to 5°C.

11. Step of cooling the OLED (10) by driving the cooling system (20); A step of measuring the temperature of the OLED or an area adjacent to the OLED using a temperature sensor (30, 31); and A step of starting to drive the OLED when the measured temperature is lower than or equal to a preset cooling temperature; A driving method of an OLED device including:

12. In paragraph 11, A driving method for an OLED device, characterized in that the cooling temperature is a temperature at which light having a saturated power density can be output without failure when the OLED is driven after being cooled to the cooling temperature, or a temperature at which the temperature measured by the temperature sensor (30, 31) when the OLED outputs light having a saturated power density is not heated to a temperature higher than body temperature or a protein denaturation temperature.

13. In paragraph 11 or 12, A driving method for an OLED device, characterized in that the cooling temperature is 5°C or lower or 0°C or lower.

14. In any one of paragraphs 11 to 13, A driving method of an OLED device, characterized in that it further includes a step of lowering the power applied to the OLED or stopping the driving of the OLED when the temperature measured by the temperature sensor (30, 31) after the OLED (10) is driven is higher than the body temperature or protein denaturation temperature.

15. In any one of paragraphs 11 to 14, A driving method for an OLED device, characterized in that the cooling temperature is -15°C to 0°C, and further includes a step of controlling the temperature measured by the temperature sensor (30, 31) after the OLED is driven to be maintained in the range of 0°C to 5°C.

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