Patent Publication Number: US-9892687-B2

Title: Organic light-emitting diode (OLED) display unit

Description:
BACKGROUND OF THE INVENTION 
     Field of Invention 
     The present invention relates to a technical field of a display unit, and more particularly to an organic light-emitting diode (OLED) display unit. 
     Description of Prior Art 
     An organic light-emitting diode (OLED) display with self-illuminated characteristic has a wide viewing angle and a power-saving and thus is widely applicable to mobile phones and television sets. 
     The OLED display comprises a plurality of OLEDs which are driven by a driving circuit when a voltage (e.g. OVDD) level is inputted to the driving circuit. However, since a driving loading easily makes an effect on the driving circuit so that the real voltage exerted on the OLEDs fluctuates irregularly, which disadvantageously downgrades the uniformity of the display unit and reduces the display effect. 
     Consequently, there is a need to develop an organic light-emitting diode (OLED) display to solve the problems of the conventional technique. 
     SUMMARY OF THE INVENTION 
     One objective of the present invention is to provide organic light-emitting diode (OLED) display unit to solve the technical problems of the irregular fluctuation of the real voltage on the OLED due to the driving loading effect, which disadvantageously downgrades the uniformity of the display unit. 
     To solve the above-mentioned problems, the present invention sets forth an OLED display unit, comprising: a first substrate comprising: a plurality of data lines, for being inputted by data signals; a plurality of scanning lines, for being inputted by scanning signals; a plurality of organic light-emitting units, for being defined and enclosed by the data lines and the scanning lines wherein the organic light-emitting unit comprises an OLED; and a plurality of pixel-driving units, each of the organic light-emitting units being corresponded to one pixel-driving unit wherein the pixel-driving unit connected to the OLED comprises a power input terminal and an illumination control terminal; the pixel-driving unit controls a display status of the OLED based on the data signals, the scanning signals and a voltage inputted to the power input terminal; and the illumination control terminal is inputted by an illumination control signal for controlling whether the OLED illuminates or not; 
     a second substrate disposed to the first substrate oppositely; and 
     a driving circuit, comprising: a power module, for being used to input an initial voltage to the power input terminal wherein the power module comprises a first output terminal for inputting an initial voltage to the power input terminal; and a regulation unit, for regulating the initial voltage, which is outputted from the power input terminal, based on a real voltage of the power input terminal in the pixel-driving unit for equalizing the real voltage of the power input terminal to a predetermined voltage; wherein the regulation unit comprises a first input terminal, a second input terminal and a second output terminal; the first input terminal is inputted by the initial voltage of the power module; and the second input terminal is inputted by the real voltage of the power input terminal; the second output terminal outputs a feedback voltage to the first output terminal; and wherein the first output terminal is connected to the first input terminal, the second input terminal is connected to the power input terminal, and the second output terminal is connected to the first output terminal. 
     In the OLED display unit, the regulation unit is used to decrease a voltage of the first output terminal when the real voltage of the power input terminal increases. 
     In the OLED display unit, the regulation unit is used to increase the voltage of the first output terminal when the real voltage of the power input terminal decreases. 
     In the OLED display unit, the regulation unit comprises: a blocking sub-unit, for being used to block the real voltage of the power input terminal, which is inputted to the second input terminal, for generating an alternating regulation voltage; and a feedback sub-unit, for feedbacking and regulating the initial voltage of the power module based on the alternating regulation voltage for generating a feedback voltage. 
     In the OLED display unit, when the alternating feedback voltage is greater than the predetermined voltage, the feedback sub-unit acquires a negative feedback voltage based on the alternating regulation voltage and the initial voltage of the power module for decreasing the voltage of the first output terminal. 
     In the OLED display unit, when the alternating feedback voltage is less than the predetermined voltage, the feedback sub-unit acquires a positive feedback voltage based on the alternating regulation voltage and the initial voltage of the power module for increasing the voltage of the first output terminal. 
     In the OLED display unit, the feedback voltage is a difference value between the initial voltage of the power module and the alternating feedback voltage. 
     In the OLED display unit, the regulation unit comprises a first resistance, a second resistance, a third resistance, a fourth resistance, a differential amplifier and a first capacitor, and the differential amplifier comprises an original input terminal, a feedback input terminal and a differential output terminal; 
     wherein the first input terminal is connected to the original input terminal by way of the first resistance; 
     wherein the second input terminal is connected to one terminal of the first capacitor, the other terminal of the first capacitor is connected to one terminal of the third resistance, and the other terminal of the third resistance is connected to the feedback input terminal; and 
     wherein the second output terminal is connected to the differential output terminal, the fourth resistance is connected between the feedback input terminal and the differential output terminal, and the original input terminal is grounded by way of the second resistance. 
     In the OLED display unit, the pixel-driving unit comprises a first switch transistor, a second switch transistor, a third switch transistor and a second capacitor; 
     wherein the control terminal of the first switch transistor is connected to the scanning line and the input terminal of the first switch transistor is connected to data line; 
     wherein the control terminal of the third switch transistor is connected to the illumination control terminal, the input terminal of the third switch transistor is connected to the power input terminal, and the output terminal of the third switch transistor is connected to the input terminal of the second switch transistor; 
     wherein the control terminal of the second switch transistor is connected to the output terminal of the first switch transistor, the output terminal of the second switch transistor is connected to an anode of the OLED, and the anode of the OLED is connected to the low voltage level with direct current; 
     wherein the output terminal of the first switch transistor is connected to the input terminal of the second switch transistor by way of the second capacitor. 
     To solve the above-mentioned problems, the present invention sets forth an OLED display unit, comprising: 
     a first substrate comprising: a plurality of data lines, for being inputted by data signals; a plurality of scanning lines, for being inputted by scanning signals; a plurality of organic light-emitting units, for being defined and enclosed by the data lines and the scanning lines wherein the organic light-emitting unit comprises an OLED; and a plurality of pixel-driving units, each of the organic light-emitting units being corresponded to one pixel-driving unit wherein the pixel-driving unit connected to the OLED comprises a power input terminal; the pixel-driving unit controls a display status of the OLED based on the data signals, the scanning signals and a voltage inputted to the power input terminal; 
     a second substrate disposed to the first substrate oppositely; and 
     a driving circuit, comprising: a power module, for being used to input an initial voltage to the power input terminal; and a regulation unit, for regulating the initial voltage, which is outputted from the power input terminal, based on a real voltage of the power input terminal in the pixel-driving unit for equalizing the real voltage of the power input terminal to a predetermined voltage. 
     In the OLED display unit, the power module comprises a first output terminal for inputting an initial voltage to the power input terminal; 
     wherein the regulation unit comprises a first input terminal, a second input terminal and a second output terminal; the first input terminal is inputted by the initial voltage of the power module; and the second input terminal is inputted by the real voltage of the power input terminal; the second output terminal outputs a feedback voltage to the first output terminal; and 
     wherein the first output terminal is connected to the first input terminal, the second input terminal is connected to the power input terminal, and the second output terminal is connected to the first output terminal. 
     In the OLED display unit, the regulation unit is used to decrease a voltage of the first output terminal when the real voltage of the power input terminal increases. 
     In the OLED display unit, the regulation unit is used to increase the voltage of the first output terminal when the real voltage of the power input terminal decreases. 
     In the OLED display unit, the regulation unit comprises: a blocking sub-unit, for being used to block the real voltage of the power input terminal, which is inputted to the second input terminal, for generating an alternating regulation voltage; and a feedback sub-unit, for feedbacking and regulating the initial voltage of the power module based on the alternating regulation voltage for generating a feedback voltage. 
     In the OLED display unit, when the alternating feedback voltage is greater than the predetermined voltage, the feedback sub-unit acquires a negative feedback voltage based on the alternating regulation voltage and the initial voltage of the power module for decreasing the voltage of the first output terminal. 
     In the OLED display unit, when the alternating feedback voltage is less than the predetermined voltage, the feedback sub-unit acquires a positive feedback voltage based on the alternating regulation voltage and the initial voltage of the power module for increasing the voltage of the first output terminal. 
     In the OLED display unit, the feedback voltage is a difference value between the initial voltage of the power module and the alternating feedback voltage. 
     In the OLED display unit, the regulation unit comprises a first resistance, a second resistance, a third resistance, a fourth resistance, a differential amplifier and a first capacitor, and the differential amplifier comprises an original input terminal, a feedback input terminal and a differential output terminal; 
     wherein the first input terminal is connected to the original input terminal by way of the first resistance; 
     wherein the second input terminal is connected to one terminal of the first capacitor, the other terminal of the first capacitor is connected to one terminal of the third resistance, and the other terminal of the third resistance is connected to the feedback input terminal; and 
     wherein the second output terminal is connected to the differential output terminal, the fourth resistance is connected between the feedback input terminal and the differential output terminal, and the original input terminal is grounded by way of the second resistance. 
     In the OLED display unit, the pixel-driving unit further comprises an illumination control terminal which is inputted by an illumination control signal for controlling whether the OLED illuminates or not, and the pixel-driving unit further comprises: a first switch transistor, a second switch transistor, a third switch transistor and a second capacitor; 
     wherein the control terminal of the first switch transistor is connected to the scanning line and the input terminal of the first switch transistor is connected to data line; 
     wherein the control terminal of the third switch transistor is connected to the illumination control terminal, the input terminal of the third switch transistor is connected to the power input terminal, and the output terminal of the third switch transistor is connected to the input terminal of the second switch transistor; 
     wherein the control terminal of the second switch transistor is connected to the output terminal of the first switch transistor, the output terminal of the second switch transistor is connected to an anode of the OLED, and the anode of the OLED is connected to the low voltage level with direct current; 
     wherein the output terminal of the first switch transistor is connected to the input terminal of the second switch transistor by way of the second capacitor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic circuit view of a pixel driving unit according to one embodiment of the present invention; 
         FIG. 2  is a schematic waveform view of the driving voltage fluctuation of the conventional OLED; 
         FIG. 3  is a schematic circuit view of a regulation unit disposed in the driving circuit according to one embodiment of the present invention; and 
         FIG. 4  is a schematic circuit view of regulating the voltage of the regulation unit according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following embodiments refer to the accompanying drawings for exemplifying specific implementable embodiments of the present invention. Furthermore, directional terms described by the present invention, such as upper, lower, front, back, left, right, inner, outer, side, etc., are only directions by referring to the accompanying drawings, and thus the used directional terms are used to describe and understand the present invention, but the present invention is not limited thereto. In the drawings, the same reference symbol represents the same or a similar component. 
     Please refer to  FIG. 1 , which is a schematic circuit view of a pixel driving unit according to one embodiment of the present invention. 
     The organic light-emitting diode (OLED) display unit in the present invention comprises a first substrate, a second substrate disposed to the first substrate oppositely, and a driving a circuit. As shown in  FIG. 1 , the first substrate comprises a plurality of data lines  12 , a plurality of scanning lines  11 , a plurality of organic light-emitting units, and a plurality of pixel-driving units  13 . The data lines  12  are used to input the data signals. The scanning lines  11  are used to input the scanning signals. The organic light-emitting units are defined and enclosed by the data lines  12  and the scanning lines  11  wherein the organic light-emitting units comprise OLEDs L 1 . 
     Each of the organic light-emitting units corresponds to one pixel-driving unit  13  wherein the pixel-driving unit  13  comprises a power input terminal  14  and the pixel-driving unit  13  connects to the OLED L 1 . The pixel-driving unit  13  controls the display status of the OLED L 1  based on the data signal, the scanning signal and the voltage (e.g. OVDD) inputted to the power input terminal  14 . 
     The driving circuit comprises a power module and a regulation unit. 
     The power module is used to input an initial voltage to the power input terminal  14 . The regulation unit regulates the initial voltage, which is outputted from the power input terminal  14 , based on the real voltage of the power input terminal  14  in the pixel-driving unit  13  so that the real voltage of the power input terminal  14  is equal to a predetermined voltage. 
     The pixel-driving unit  13  further comprises an illumination control terminal  15  wherein the illumination control terminal  15  is inputted by an illumination control signal for controlling whether the OLED illuminates or not. When the illumination control signal is in high level, the OLED illuminates and when the illumination control signal is in low level, the OLED does not illuminate. 
     As shown in  FIG. 2 , the waveform of the illumination control signal is indicated by the numeral  21  in  FIG. 2  and the real voltage of the power input terminal  14  is indicated by the numeral  22  in  FIG. 2 . When the voltage of illumination control signal changes from high to low or from low to high, the real voltage  22  of the power input terminal  14  induces the positive pulse and negative pulse due to the resistance fluctuation of the loading. The positive pulse and negative pulse disadvantageously affects the driving circuit of the OLED and further downgrades the uniformity. 
     The pixel-driving unit  13  comprises a first switch transistor T 1 , a second switch transistor T 2 , a third switch transistor T 3  and a second capacitor Cst. 
     The control terminal of the first switch transistor T 1  is connected to the scanning line  11  and the input terminal of the first switch transistor T 1  is connected to data line  12 . The control terminal of the third switch transistor T 3  is connected to the illumination control terminal  15 , the input terminal of the third switch transistor T 3  is connected to the power input terminal  14 , and the output terminal of the third switch transistor T 3  is connected to the input terminal of the second switch transistor T 2 . 
     The control terminal of the second switch transistor T 2  is connected to the output terminal of the first switch transistor T 1 . The output terminal of the second switch transistor T 2  is connected to the anode of the OLED L 1  wherein the anode of the OLED L 1  is connected to the low voltage level (e.g. OVSS) with direct current. The output terminal of the first switch transistor T 1  is connected to the input terminal of the second switch transistor T 2  by way of the second capacitor Cst. 
     Preferably, the power module comprises a first output terminal wherein the first output terminal inputs an initial voltage to the power input terminal  14 . The regulation unit comprises a first input terminal  23 , a second input terminal  24  and a second output terminal  25 . The first input terminal  23  is inputted by the initial voltage of the power module. The second input terminal  24  is inputted by the real voltage of the power input terminal  14 . The second output terminal  25  outputs a feedback voltage to the first output terminal. 
     The first output terminal is connected to the first input terminal  23 , the second input terminal  24  is connected to the power input terminal  14 , and the second output terminal  25  is also connected to the first output terminal. 
     Preferably, the regulation unit is used to decrease the voltage of the first output terminal when the real voltage of the power input terminal  14  increases. Furthermore, the regulation unit is used to increase the voltage of the first output terminal when the real voltage of the power input terminal  14  decreases. 
     Preferably, the regulation unit comprises a blocking sub-unit and a feedback sub-unit. 
     The blocking sub-unit is used to block the real voltage of the power input terminal  14 , which is inputted to the second input terminal  24 , for generating an alternating regulation voltage. In other words, the component of the direct current is filtered and the rest of alternating current component is inputted to the feedback sub-unit. Preferably, the blocking sub-unit is a capacitor. The feedback sub-unit feedbacks and regulates the initial voltage of the power module based on the alternating regulation voltage for generating a feedback voltage. In one embodiment, the feedback sub-unit is a differential amplifier. 
     For example, the detecting module detects the real voltage of the power input terminal  14 . As shown in  FIG. 4 , the real voltage  31  of the power input terminal  14  is composed of direct current component and alternating current component. In one case, the voltage with direct current is 10V (voltage) to be inputted to the second input terminal  24 . The real voltage  31  is processed by the blocking sub-unit to form the high frequency pulse signal  32  (only the alternating current component remaining with the voltage basis 0V). Meanwhile, the high frequency pulse signal  32  with the alternating current component is inputted to the regulation sub-unit. The regulation sub-unit processes the alternating current component and initial voltage of the power module to form a compensation signal  33  (i.e. the feedback voltage) and the compensation signal  33  is outputted to the first input terminal so that the real voltage of the power input terminal maintains constant. 
     Preferably, as shown in  FIG. 3 , the regulation unit comprises a first resistance R 1 , a second resistance R 2 , a third resistance R 3 , a fourth resistance R 4 , a differential amplifier  26  and a first capacitor C 1  wherein the differential amplifier  26  has an original input terminal  27 , a feedback input terminal  28  and a differential output terminal. 
     The first input terminal  23  is connected to the original input terminal  27  by way of the first resistance R 1 . 
     The second input terminal  24  is connected to one terminal of the first capacitor C 1 , the other terminal of the first capacitor C 1  is connected to one terminal of the third resistance R 3 , and the other terminal of the third resistance R 3  is connected to the feedback input terminal  28 . 
     The second output terminal  25  is connected to the differential output terminal, the fourth resistance R 4  is connected between the feedback input terminal  28  and the differential output terminal, and the original input terminal  27  is grounded by way of the second resistance R 2 . Preferably, the resistance ratio between the first resistance R 1  and the second resistance R 2  is one. 
     Preferably, when the alternating feedback voltage is greater than the predetermined voltage, the feedback sub-unit acquires a negative feedback voltage based on the alternating regulation voltage and the initial voltage of the power module for decreasing the voltage of the first output terminal. 
     For an example of predetermined voltage 2V, when the alternating feedback voltage is 12V, the differential output terminal of the differential amplifier is −2V and the feedback voltage −2V is inputted to the first output terminal of the power module so that the real voltage of the power input terminal is equal to 10V. 
     Preferably, when the alternating feedback voltage is less than the predetermined voltage, the feedback sub-unit acquires a positive feedback voltage based on the alternating regulation voltage and the initial voltage of the power module for increasing the voltage of the first output terminal. 
     For an example of predetermined voltage 2V, when the alternating feedback voltage is 8V, the differential output terminal of the differential amplifier is 2V and the feedback voltage 2V is inputted to the first output terminal of the power module so that the real voltage of the power input terminal is equal to 10V. 
     Preferably, the feedback voltage is the difference value between the initial voltage of the power module and the alternating feedback voltage. 
     The OLED display unit in the present invention adds a voltage regulation unit to the conventional driving circuit and regulates the voltage inputted to the OLED in real-time to avoid the driving voltage fluctuation so as to upgrade the uniformity of the display unit and increase the display effect. 
     As is understood by a person skilled in the art, the foregoing preferred embodiments of the present invention are illustrative rather than limiting of the present invention. It is intended that they cover various modifications and similar arrangements be included within the spirit and scope of the present invention, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures.