Abstract:
A power supply unit adapted to prevent or reduce damage to devices when the devices receive power with an abnormal voltage, and an organic light emitting display device using the same. An embodiment of the present invention provides a power supply unit, including: a power block including an input terminal for receiving an input power, an output terminal for outputting an output power, and an enable terminal for receiving an enable signal for controlling a driving of the power block; an input power unit configured to concurrently transfer the input power to the input terminal and the enable terminal; and a controller configured to control a voltage of the input power transferred to the enable terminal to determine the driving time point of the power block, and an organic light emitting display device using the same.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2009-0016731, filed on Feb. 27, 2009, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to a power supply unit and an organic light emitting display device, and more particularly, to a power supply unit that stabilizes its output voltage to prevent or reduce damage to devices powered by the power supply unit, and an organic light emitting display device using the same. 
     2. Discussion of Related Art 
     Recently, various flat panel display devices having less weight and volume than a cathode ray tube (CRT) display device have been developed. The various flat panel display devices include a liquid crystal display device, a field emission display device, a plasma panel display device, an organic light emitting display device, etc. 
     Among the display devices, the organic light emitting display device displays an image using organic light emitting diodes (OLEDs) that generate light by recombination of electrons and holes generated corresponding to a flow of current. 
     The organic light emitting diode includes a light emitting layer of an organic material. 
     Such an organic light emitting display device has relatively high color reproducibility and is relatively thin, so that its applications are expanding to various markets, e.g., cellular phone, PDA, and MP3 markets. 
     The organic light emitting display device as described above operates by receiving input power from a power supply unit. Here, the power supply unit operates by receiving the input power and an enable signal that determines the operation of the power supply unit, wherein the input power is transferred directly to the power supply unit in the early stage of driving, but the enable signal is transferred through a timing controller. Therefore, the enable signal is transferred to the power supply unit after the timing controller is operated so that the enable signal is transferred to the power supply unit, having a time difference, after the input power is transferred. 
     Due to this time difference as described above, the power supply unit may malfunction and lead to a case where a voltage from an output power of the power supply unit is output before the power supply unit should normally operate so that the voltage from the output power is abruptly raised. 
     If the voltage from the output power is abruptly raised as described above, components supplied with voltage by the power supply unit may be damaged. 
     SUMMARY OF THE INVENTION 
     An aspect of an embodiment of the present invention is directed toward a power supply unit that prevents damage to or protects devices from receiving power with an abnormal voltage from the power supply unit, and an organic light emitting display device using the same. 
     According to a first embodiment of the present invention, there is provided a power supply unit, including: a power block including an input terminal for receiving an input power, an output terminal for receiving an output power, and an enable terminal for receiving an enable signal to control a driving of the power block; an input power unit configured to concurrently transfer the input power to the input terminal and the enable terminal; and a controller configured to control a voltage of the input power transferred to the enable terminal to determine a driving time point of the power block. 
     According to a second embodiment of the present invention, there is provided an organic light emitting display device, including: a display region configured to receive data signals and scan signals to display an image; a timing controller configured to generate control signals; a data driver configured to transfer the data signals to the display region; a scan driver configured to transfer the scan signals to the display region; and a power supply unit configured to transfer a driving power to at least one of the display region, the data driver, and the scan driver, wherein the power supply unit includes: a power block that includes an input terminal for receiving an input power, an output terminal for receiving an output power, and an enable terminal for receiving an enable signal to control a driving of the power block; an input power unit configured to concurrently transfer the input power to the input terminal and the enable terminal; and a controller configured to control a voltage of the input power transferred to the enable terminal to determine a driving time point of the power block. 
     According to a third embodiment of the present invention, there is provided a method for driving an organic light emitting display device with a power supply unit including a power block and a controller, the method including: concurrently transferring an input power to an input terminal and an enable terminal of the power block, and suspending the power block from outputting an output voltage in accordance with a voltage of the input power transferred to the enable terminal; transferring a control signal to the controller to adjust the voltage input into the enable terminal to enable the power block to be driven; and starting driving of the organic light emitting display device with the output voltage output from the power block. 
     With the power supply unit and the organic light emitting display device using the same according to the embodiments of the present invention, the power supply unit stably outputs the voltage from the output power, making it possible to prevent or reduce damage to the devices and the organic light emitting display device from being damaged from receiving the output power from the power supply unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, together with the specification illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention. 
         FIG. 1  is a schematic diagram showing an organic light emitting display device according to an embodiment of the present invention; 
         FIG. 2  is a schematic diagram showing a power supply unit of  FIG. 1 ; and 
         FIG. 3  is a timing diagram showing the operation of the power supply unit of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, certain exemplary embodiments according to the present invention will be described with reference to the accompanying drawings. Here, when a first element is described as being coupled or connected to a second element, the first element may be not only directly coupled to the second element but may also be indirectly coupled to the second element via a third element. Further, some of the elements that are not essential to the complete understanding of the invention are omitted for clarity. Also, like reference numerals refer to like elements throughout. 
     Hereinafter, exemplary embodiments according to the present invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a schematic diagram showing an organic light emitting display device according to an embodiment of the present invention. Referring to  FIG. 1 , the organic light emitting display device includes a display region  100 , a data driver  200 , a scan driver  300 , a timing controller  400 , and a power supply unit  500 . 
     The display region  100  includes a plurality of pixels  101 , wherein each pixel  101  includes an organic light emitting diode that emits light corresponding to a flow of current. The display region  100  is provided with n number of scan lines S 1 , S 2 , . . . , Sn−1 and Sn extending in a row direction for transferring scan signals, and m number of data lines D 1 , D 2 , . . . , Dm−1 and Dm extending in a column direction for transferring data signals. 
     The display region  100  is driven by receiving a first power ELVDD and a second power ELVSS from the power supply unit  500 . Therefore, the display region  100  displays an image by allowing a current to be flowed to the organic light emitting diodes to emit light in accordance with the scan signals, the data signals, the first power ELVDD, and the second power ELVSS. 
     The data driver  200  generates data signals by using image signals having red, blue, and green components. The data driver  200  applies the generated data signals via the data lines D 1 , D 2 , . . . , Dm−1, and Dm coupled to the data driver  200  to the display region  100 . Also, the data driver  200  is operated by receiving driving voltage from the power supply unit  500 . 
     The scan driver  300 , which generates scan signals, is coupled to the scan lines S 1 , S 2 , . . . , Sn−1, and Sn to transfer the scan signals to a specific row of pixels  101  of the display region  100 . The pixels  101  provided with the scan signals are provided with the data signals output from the data driver  200  so that the voltages corresponding to the data signals are transferred to the pixels  101 . The scan driver  300  is operated by receiving the driving voltage from the power supply unit  500 . 
     The timing controller  400  controls the driving of the data driver  200 , the scan driver  300 , and the power supply unit  500 . In particular, the timing controller  400  transfers an enable signal (enable) to the power supply unit  500  to determine a time when output power is output from the power supply unit  500 . 
     The power supply unit  500  transfers the output voltage to the display region  100 , the data driver  200 , the scan driver  300 , and the timing controller  400  as the driving power to allow them to be driven. The power supply unit  500  is driven by the enable signal enable transferred from the timing controller  400  and the voltage from the input power Vin, wherein the driving is suspended by the input power in the early stage of driving, and the operation is determined by the enable signal enable after a set or predetermined time elapses. Therefore, the operation of the power supply unit  500  is controlled by the input power before the enable signal enable output from the timing controller  400  in the early stage of driving reaches the power supply unit  500 . 
       FIG. 2  is a schematic diagram showing a power supply unit of  FIG. 1 . Referring to  FIG. 2 , the power supply unit  500  includes a power block  510  that receives an input power Vin to output an output power Vout, an input power unit  520  that transfers the input power Vin to the power block  510 , and a controller  530  that controls the input power unit  520 . 
     The power block  510  is formed in, for example, an IC chip shape and performs an operation to receive the input power Vin through an input terminal VCC and to output the output power Vout through an output terminal (out). Also, whether the power block  510  is operated is determined by a signal input through an enable terminal EN. The power block  510  is operated when the signal transferred through the enable terminal EN is in a high state, according to an embodiment of the present invention, and is suspended when the signal transferred through the enable terminal EN is in a low state. 
     The input terminal VCC and the enable terminal EN of the power block  510  are coupled to the input power unit  520 . More specifically, the input terminal VCC of the power block  510  is coupled to a first node N 1 , and the enable terminal EN thereof is coupled to a second node N 2 . 
     The input power unit  520  includes a first resistor R 1  and a capacitor C, wherein the input power Vin, the first electrode of the capacitor C 1 , and one end of the first resistor R 1  are coupled to the first node N 1 . The other end of the first resistor R 1  is coupled to the second node N 2 . 
     The controller  530  includes a transistor Q 1  and a second resistor R 2 , wherein the first electrode of the transistor Q 1  is coupled to the second node N 2 . The second electrode of the transistor Q 1  is coupled to one end of the second resistor R 2 , and the gate thereof receives a control signal transferred from the timing controller  400 . The first electrode and the second electrode of the transistor Q 1  may be referred to as a source or a drain. The second resistor R 2  whose one end is coupled to the second electrode of the transistor Q 1  has the other end coupled to a ground (e.g., 0V). 
       FIG. 3  is a timing diagram showing the operation of the power supply unit of  FIG. 2 . Reviewing the operation of the power supply unit  500  constituted as above with reference to  FIG. 3 , the enable signal enable is not transferred during a period T 1  where the driving starts. Thereby, the transistor Q 1  that is, for example, an NMOS type is in a turn-off state. The input power Vin, which is continuously maintained at a set or predetermined voltage by the capacitor C, is transferred to the input terminal VCC. Also, the enable terminal EN receives the input power Vin through the first resistor R 1 . Here, the operation of the power block  510  is stopped by receiving a low voltage at its enable terminal EN which is coupled to the second node N 2  at the low voltage resulted from the voltage distribution or division of a voltage of the input power Vin between the internal resistance within the power block  510  and the first resistor R 1 . 
     In other words, the enable terminal EN receives the signal in a low state at the same time point when the input power Vin is transferred to the input terminal VCC. Therefore, the power block  510  can be controlled even before the enable signal enable is output from the timing controller  400 . Consequently, the abrupt change of voltage output from the output terminal out can be blocked or prevented. 
     The enable signal enable maintains a low state during a period T 2  where the timing controller  400  starts to operate by receiving power to transfer a signal in a low state to the power supply unit  500  so that the transistor Q 1  is in a turn-off state. Therefore, the output power is not output from the output terminal out by performing the same operation as that in the T 1  period. 
     Thereafter, at the time point when the output voltage is to be output from the output terminal out of the power supply unit  500 , the enable signal enable in a high state is output from the timing controller  400  so that the power supply unit  500  is driven to output its output voltage. At this time, the transistor Q 1  is in a turn-on state. If the transistor Q 1  is in a turn-on state, the first resistor R 1  and the second resistor R 2  are coupled in series between the input power Vin and the ground, and therefore, the voltage divided by the first resistor R 1  and the second resistor R 2  is transferred to the second node N 2 . The voltage in a high state is formed at the second node N 2  by a suitable resistance ratio between the first resistor R 1  and the second resistor R 2 . In other words, a signal in a high state is transferred to the enable terminal EN. 
     If the signal in a high state is transferred to the enable terminal EN, normal output voltage is output through the output terminal out so that the power supply unit  500  outputs a set or predetermined output voltage. 
     While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.