TWI259020B - Pixels in an AMOLED (active matrix organic light-emitting diode) panel - Google Patents

Abstract

A pixel structure in an active matrix organic light-emitting diode (AMOLED) panel is disclosed. The pixel includes a 2TIC (2 transistors and one storage capacitor) structure and a dummy switch transistor controlled by an inverted scan signal. Furthermore, a scan signal with sloped/step rising edges is used to control on/off of switch transistors. In the invention, clock feed-through (CFT) effects are cancelled, capacitance of the storage capacitor is reduced, and aperture ratios of the pixel are improved.

Description

1259020 16029twf.doc/g IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to a substrate for an Active Matrix Organic Light-Emitting Diode (AMOLED) panel ( Pixel) structure, and in particular, a pixel structure that utilizes a dummy transistor to reduce the clock feed effect. [Prior Art] In recent years, the development of flat panel display technology has been continuously updated. Among them, Organic Light_Emitting Diode (OLED) is also called organic electroluminescence (〇rganiCEiectr〇iuminesence, 〇EL), and has other A new generation of technologies that are difficult to achieve with flat panel display technology, including power saving, ultra-thin thickness, light weight, self-illumination, no viewing angle limitation, fast response speed, high photoelectric efficiency, no need for backlight structure and color filter structure, bureau contrast, rij Brightness efficiency, high brightness, multi-color and color (RGB) components make this force, the use of a wide temperature range, etc., is considered to be the most promising planar display technology in the future. The principle of OLED illumination is to use the characteristics of the material, the electron transport layer Electron Transport Layer, ETL}, the hole transport layer (HTL) and the luminescent material layer (Emiuing Μ_Γί&1

Layer, EML) combines the form of electron excitation back to the ground state, and the excess energy is generated in the form of light waves _' thus illuminating elements of different wavelengths. Currently, OLEDs are mainly used in mobile phone handsets, car displays, and PDA panels. The LEDs can be distinguished according to their driving methods: active driving 1259020 16029twf.doc/g type active diode OLED (AMOLED) and passive driving OLED (PMOLED). The pixel structure in the OLED is, for example, 2T1C (dual transistor + single capacitor). FIG. 1 shows a circuit diagram of a conventional pixel applied to an active-drive organic light-emitting diode (AMOLED) panel. - As shown in FIG. 1, the pixel 10 includes a switching transistor (MP), a driving transistor (MP2), a storage capacitor (CST 1), and an organic light-emitting diode element (LEm). Fig. 10 is a 2T1C structure. .. Switching transistor Μρι can be used as image data to enter the storage capacitor CST t switch and address the transistor MP2 can exist · stored electricity. = Sfl voltage value is converted into current, and finally drive organic hairpin 〇 LED1 ' at the same time The gray scale is not controlled by modulating different current values. 2 The source of the transistor MP1 receives the image data signal VDATA, MP Ϊ signal SCAN, and the button is connected to the driving electric pole. The source voltage vdd is lightly coupled to the source of the driving transistor mP2. %CST1 is coupled to the power supply voltage VDD盥 driving the electric mail and the second light === 0^ 〇 之^ 檐 二 二 ^ ^ ^ ^ ^ ' ' ' The crystal ΜΡ1 will turn on, and the data level representing the brightness of 8 6 1259020 16029twf.doc/g = will be applied to the data signal vdat^ at this time, = CST 1 will be charged or discharged, and drive the transistor MP2: the pressure will be Pull to the data signal VDATA. The total gate voltage of each transistor MP2 will be stored by the capacitance m = , and the pole-source voltage between the moving transistors MP2 will flow through (10) rnt k . OLED1 will produce brightness based on this current. When the potential of the scanning signal SCAN is set by the logic low potential day _ transistor MP1 t is off state, but the logic ":" knows that the domain SCAN will be closed by the switching transistor to cut the gate _ 汲 声 声 电容The voltage of the gate electrode of the driving transistor Mp2 is such that the gate electrode of the drive body and the body 2 is unexpectedly increased. This voltage _ combined amount will be based on the ratio of the parasitic capacitance of the switching capacitor CST1 to the switching transistor Μρι. That is, when the ratio of the (storage capacitance CST1) / (the parasitic capacitance value of the switching transistor 1^] 1) is larger, the voltage coupling amount is smaller, and vice versa. This effect is called the clock feed (cl〇ck feed_thr〇ugh, CFT) phenomenon. The cFT specification affects the gate voltage of the driving transistor MP2, which in turn affects the current and brightness of the OLED1. There are two conventional practices to avoid cft specs. First, the large capacitance Cst is used to reduce the voltage coupling amount of the CFT, and the large electric valley Cst will occupy a large layout (iay〇ut) area, thereby reducing the aperture ratio. The second 'predicts the possible CFT effect, shifting the different k-values after the input signal VDATA. For example, the 1259020 16029twf.doc/g VDATA should be 2V. After the CFT is considered, the VDATA is shifted to 1V. However, because the process drift is not necessarily the same every time, it is difficult to have a consistent displacement value. In addition, it will even increase the design complexity of the driver circuit of the pixel. Therefore, there is a need for a novel germanium structure applied to an AMOLED panel which avoids the clock feed effect and has a south aperture ratio. SUMMARY OF THE INVENTION The present invention provides a pixel applied to an AMOLED panel that utilizes a combination of a pseudo-switching transistor and an inverted post-scanning signal to cancel/overcome the clock feed effect. The present invention also provides a halogen for use in an AMOLED panel, which utilizes a pen-transistor transistor to further reduce the capacitance of the storage capacitor. The invention further provides a pixel applied to an AMOLED panel, which uses a ramp-up/step scan signal to further reduce the + capacitance of the storage capacitor. For this reason, the present invention proposes a pixel applied to a light-emitting diode panel, comprising: a switch module that receives an image data signal VDATA, and whose off state is controlled by a (four) SCAN; _ _ group, _ to: = Mo group, its on/off state is controlled by another scan signal sc fiber, and: the scan signal SCAN transition state will make the SCANB transfer and drive / illumination module, which is connected to the pseudo switch module , ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The secret effect is offset. Peak Crane / Light Module

The source of the switching body MP3 receives the image data signal vdata, "the gate receives the first-scan signal SCAN, and the secret is connected to the internal node I 1259020] 6029 twf.doc / g according to a preferred embodiment of the present invention The pixel structure, the scan signal SCANB is an inverted signal of the scan signal scan, or an inverted-delayed signal, or an inverted-displaced signal. The pixel structure, switching mode according to the preferred embodiment of the present invention. The set includes a switching transistor. According to the halogen structure of the preferred embodiment of the present invention, the pseudo-switching electrical body includes one or more dummy switching transistors. The pseudo-switching transistor further includes a capacitive transistor. According to the pixel structure of the preferred embodiment of the present invention, the rising edge of the scan signal SCAN is a diagonal line or a step type. Benming uses a dummy transistor to reduce clock feed. The effect can also greatly reduce the capacitance value and increase the aperture ratio (Aperture rati〇), which is beneficial to the mass production of small-sized panels. In order to make the features and advantages of the present invention more obvious, the following is a special More The embodiments are described in detail below with reference to the accompanying drawings. [Embodiment] Several preferred embodiments will be described below to illustrate the main spirit and architecture of the present invention. The circuit block diagram of the first preferred embodiment, as shown in Fig. 2, is applied to the pixels of the AM0 LED panel, the switches MP3 and MP4, the driving transistor MI>5, the storage capacitor CST 2 and the organic light emitting diode 2 The body element 〇led2. 9 8 1259020 16029twf.doc/g The source of the μ switch transistor MP4 is connected to the internal node, the pole receives the second scan signal SCANB, and the drain of the gate is floating. 1 drive transistor MP5 The gate is connected to the internal node N, and its source is lightly coupled to the source voltage VDD, which is not connected to the anode of the organic light emitting diode element 2. The cathode of the organic light emitting diode element 〇LED2 is grounded. The end of CST 2 is connected to the terminal of the driving transistor MP5, and the other end is consumed to the power supply voltage VDD. • Please refer to Figure 3, which shows the waveform relationship between the scanning signals SCAN and SCANB. See that the scan signal is inverted After that, the scan signal SCANB can be obtained. Or the SCANB can be obtained by inverting the scan signal SCAN, or the scan signal SCANB can be obtained by shifting the SCAN ^ : and then shifting. 2, the scanning signal SCANB in Figure 4 and Figure 5 can be replaced by scanb, or scanb,, can still achieve the effect of the invention. On the enable (select) 昼素 2〇 (that is, the scanning signal at this time) Scan changes from high to low), the switching transistor MP3 turns on, and the other switch transistor MP4 turns off. At this time, the closed-pole 1 voltage of the driving transistor Mp5 (i.e., the potential of the node N1) is pulled to the potential of VDATA. Driving the gate of the t crystal MP5_source voltage causes the organic light emitting diode to flow through

The current of the OLED 2, in turn, causes the surface-emitting diode element qled2 to emit light. As can be seen from the combination of Fig. 2 and Fig. 3, when the pixel 2 is to be disabled, the scanning signal SCAN is turned to a high potential and the other scanning signal scanb is turned to a low potential. Therefore, the switching transistor Mp3 will be turned off but the other 8 10 1259020 switching transistor MP4 will be turned on. As described above, when the scan signal SCAN transitions (from low potential to high potential), the clock feed effect caused by the parasitic capacitance of the switching transistor Mp3 should originally cause the gate voltage of the driving transistor MP5 to be temporarily suspended. The state is pulled up; however, the clock feed effect caused by the biodegradable capacitance of the switching transistor MP4 also causes the pole voltage between the driving transistors MP5 to be temporarily pulled down. That is, the clock feed effect, which can be regarded as the parasitic capacitance of the switching transistor MP3, is substantially offset by the clock feed effect of the parasitic capacitance of the switching transistor MP4. Therefore, when the temple is to be lost, the scanning signal SCAN changes from a low potential to a potential π '. Since the CTT effect is essentially exclusive or its effect is very low, the gate voltage of the driving transistor ΜΡ5 will be essentially Maintain the #DATA bit in VDATA. In addition, as shown in FIG. 2, the pixel 2 of the present invention can also be regarded as including: the switch module 21, the pseudo switch module 22 and the driving/lighting module force. Wherein, the =core group 21 includes at least the switching transistor Mp3. The pseudo-switch module to =ST2, the driving transistor MP5 and the organic light-emitting diode element are described. According to the first embodiment of the present invention, the utilization is increased.

A dummy switch transistor MP4 is included. Drive, the light-emitting module 23 at least stores the capacitor CST2, and drives the Leidan μ... U OLED2 〇

1259020 16029twf.doc/g: Month's test 4' is a variation of Figure 2. The driver is connected to the source of the transistor ΜΡ6; the gate is connected to another reference voltage V1. ^ The adjustment of the electric body ΜΡ 6 to allow the private connection between the transistors Mp5 要 = to the potential of VDATA. 1 is closer to > material signal group 2: iHf4, pixel 4. It can also be considered as including the switch mode/pseudo-switch core set 42 and the drive/light-emitting module 43. = Ξ 11 βΘβ 11ΜΡ3 ^ ^ ^ ^ ^ ^ ί 43 to capacitive transistor ΜΡ 6 ° drive / illuminating module - _ already included storage valley CST2, drive transistor ΜΡ 5 and organic ^ one pole body 7L OLED2. , sentence 忐 ^ 忐 = transistor MP6 has the effect of deleting capacitance, so the capacitance value of the capacitor CST2 can also reduce the storage capacitance. As a result, the layout surface of the pixel 40 shown in FIG. 4 is increased by the addition of the transistor MP6. A diagram showing an electric block diagram according to a second preferred embodiment of the present invention is shown. As shown in Fig. 5, it should be secreted in the AM 〇 LED panel; the memory is included. The switching transistor MP7~MP9, the driving transistor Mp 1 〇, the stray capacitor CST 3 and the organic light emitting diode element (10) D3. The gate, the source of the off-cell crystal MP7 receives the image data signal VDATA, receives the first scan signal SCAN, and its drain is connected to the internal node N3. On, the source of the transistor MP8 is connected to the internal node N3, and the poles of the transistor are scanned for the k-number SCAN, and the drain is connected to the internal node N4. The source of the switching transistor MP9 is connected to the internal node N3, and its gate is connected to the first scan signal SCANB, and its drain is connected to the internal node 蝌. The driver package body MP10 is connected to the internal node N4, and the source is integrated with the power supply voltage lion. Wei Lilai has the ship light: the anode element of the OLED3. The cathode of the money LED component GLED3 is connected to the ground terminal VSS. The storage valley CST 31 is connected between the driving voltage of the driving transistor MP1 VDD. The relationship between the scan signals SCAN and scanb in the package diagram can be as shown in Fig. 3. - When the pixel 50 is enabled (that is, the scan signal SCAN changes from high to low at this time) The switch transistor gift is turned on, and the other switch transistor gift is turned off. At this time, the pole voltage (10) of the driving transistor Na 1 is pulled to the potential of VDATA. The driving transistor The voltage of the MP1G H source (4) will cause the current flowing through (10) to further illuminate the OLED 3. As shown in Fig. 5 and Fig. 3, when the pixel is disabled, the potential of the scanning signal S^AN changes from a logic low to a logic. High power (4) The potential of the other scan signal SCANB will change from logic high to logic low. At this time, the switching transistor MP7 and ]^8 will be _, and the switching transistor Mp9 will be turned on. Switching transistor MP 7 and MP The clock feed effect caused by the parasitic capacitance of 8 will be offset by the parasitic feed effect caused by the parasitic capacitance of the switching transistor MP9. Thus, the driving transistor Μρι〇2 gate voltage 'is the node N4 The voltage can still be maintained at the potential of vDATA. 8 13 Switch Momo switch mode

L259〇2〇 16029twf. doc/g In addition, referring to FIG. 5 again, the pixel 5〇 can also be regarded as including: , , and 5:!, the pseudo-switch module 52 and the driving/lighting module are magic. Its group 51 includes at least a switching transistor MP7. Pseudo-switching mode %52 $ pseudo-switching transistor MP8/MP9. The driving/lighting module 53 = includes a capacitor CST3, which drives the transistors Mm and = and stores 0 LED3. Knowing the polar body element from the above description, according to the second embodiment of the present invention, the dummy transistor MP8/MP9 can be used to overcome/compensate the clock effect by using a small storage voltage, thereby reducing the circuit. Brothers down, and then increase the aperture rate. The situation is that the other two sides of the dream sr are added to the effect of the present invention, and the waveform of the scanning & SCAN can be changed as shown in Fig. 6(A) and Fig. 6(B). In the figure % two

= The rising edge of the signal SCAN has a diagonal waveform. There is a stepped waveform at the rising edge of the scanning signal SCAN of the figure Y. The vth of Figure 6 (Α) represents the threshold voltage of the switching transistor (such as ΜΡ3). And Figure 6 (called V2 can be set to be slightly larger than the threshold voltage of the switching transistor (such as Μρ3). The effect of introducing the waveforms of Figure 6 (A) and Figure 6 (B) into the circuit of Figure 2 will be explained below. Referring again to FIG. 2 and FIG. 6(A), in time τΐ, the switching transistor MP3 is still not fully turned off, and the gate voltage of the driving transistor Μρ5 can be pulled to VDATA. As for the switching transistor MP3 in time Τ2 Will gradually close. Please refer to Figure 2 and Figure 6 (B) again, in time Τ3, the switch transistor 14 8 1259020 16029twf.doc / g body MP3 has not been completely closed, the gate voltage of the drive transistor Mp5 can be pulled VDATA. As for the MP3 will be completely turned off after time T4 and after T4. Using the waveforms of Figure 6(A) and (Β), the switching transistor Μρ3 can be progressively turned off, and the drive is driven before the MP3 is completely turned off. The gate voltage of the crystal Μρ5 can be pulled to VDATA, and the CFT effect caused by the switching transistor MP3 _ is further reduced, and (4) 6(4) and (8)

The waveform is ugly, but it can be further improved to reduce the capacitance of the bribe capacitor. The waveforms of Figures 6(A) and 6(B) can also be applied to the structure of Figure 4 and Figure 5. At this time, the compensation effect can be further improved. . Even if the graph is directly applied to the shot of Figure 1, the compensation effect can be obtained, and the circuit structure can be completely unmodified. In the case of ^", the switching transistor and the driving transistor are exemplified by a Ρ-type electric crystal (touch S), but the invention is not limited thereto. The ratio Z-transistor transistor and the driving transistor are changed to an N-type transistor (NM0S). 22: The connection between the waveform of SCAN and the storage capacitor must also be changed accordingly. The seeding month can also be applied to the switching/driving mode of other medium-body element D) that needs to reduce/offset the CFT effect. In the present inventor, the "gate", m/"! / light combination means "inter-component, direct coupling / coupling" or indirect coupling /_ combination". In the present invention, the use of pseudo The Ί/ or ramp-up/step scan signal caused by the opening of the transistor is used to overcome/compensate the CFT effect of the original switching transistor of 8 15 1259020 16029tvvf.doc/g. Thus, it can be used in small storage~ In the case of the CFT effect, the sigma ratio is increased and the sigma ratio is increased, and the circuit area is increased. The present invention has been disclosed in the preferred embodiment as above, but it is limited to the invention, and any (four) skilled person The scope of the present invention is defined by the scope of the appended claims. Μ% [Simple description of the drawings] Fig. 1 does not depart from the spirit and scope of the present invention. A circuit diagram of a conventional element in an active-mode OLED (AM0LED) panel. FIG. 2 is a circuit diagram of a halogen applied to an AMOLED according to a first preferred embodiment of the present invention. Figure 3 shows the waveforms of the scan signals SCAN and SCANB 4 is a circuit diagram of another pixel applied to an AMOLED panel according to a first preferred embodiment of the present invention. FIG. 5 is a circuit diagram of a pixel applied to an AMOLED panel according to a second preferred embodiment of the present invention. 6(A) and 6(B) show another waveform diagram of the scanning signal SCAN. [Main component symbol description] 10, 20, 40, 50: pixel 21 ' 41, 51 : switch module 22 ' 42 ' 52 : Pseudo-switch module 23 ' 43 ' 53 : drive / lighting module MP1, MP2, MP3, MP4, MP5, MP6, MP7, MP8, 16 8 1259020 16029twf.doc / g MP9, MP10: transistor CST1, CST2, CST3 : Storage Capacitor OLED Bu 0LED2, 0LED3: Organic Light Emitting Diode SCAN, SCANB: Scanning Signal VDATA: Image Data Signal

17

Claims (1)

1259020 16029twf.doc/g X. Patent application scope: 1. A pixel applied to a light-emitting diode panel, comprising: a switch unit that receives an image data signal and is controlled by a first scan signal; a dummy switch unit coupled to the switch unit and controlled by a second scan signal, wherein a transition state of the first scan signal causes a transition state of the second scan signal; and a driving unit is coupled to a power source a voltage and the pseudo-switching unit; a storage unit coupled to the power supply voltage and the driving unit; and a lighting unit that is lightly connected between the driving unit and a grounding terminal; wherein the first scanning signal The coupling effect of the transition state on the driving unit is substantially reduced by the coupling effect caused by the transition state of the second scanning signal to the driving unit. 2. The pixel according to claim 1, wherein the second scan signal is an inverted signal of the first scan signal, an inverted-delayed signal, and an inverted-shifted signal. Choose one of the three. 3. The pixel as described in claim 1, wherein the switch unit comprises a switch transistor having: receiving a source of the image data signal, receiving a gate of the first scan signal, and A bungee. 4. The pixel as described in claim 3, wherein the pseudo-switching unit comprises a first pseudo-switching transistor having: a source coupled to one of the drains of the switching transistor, receiving the second Scan the gate of one of the signals, as well as the pole. 5. The pixel of claim 4, wherein the dummy switch 8 18 1259020 16029 twf.doc/g unit further comprises a capacitive transistor having: a drain connected to the first dummy switching transistor The source and the drain, and the gate that receives a reference voltage. 6. The pixel of claim 3, wherein the pseudo-switching unit further receives the first scan signal, and the pseudo-switching unit comprises: a second pseudo-switching transistor having: coupled to the a source of one of the drains of the switching transistor, receiving a gate of the first scan signal, and a drain; and a third dummy switch transistor having: a drain coupled to the transistor of the switch a source receiving a gate of the second scan signal and a drain connected to one of the drains of the second dummy switch transistor. 7. The halogen as described in claim 1, wherein the rising edge of the first scanning signal is a diagonal line. 8. The element as claimed in claim 1, wherein the rising edge of the first scanning signal is stepped. • 9. The element as claimed in claim 1, wherein the light emitting diode panel is an active driven organic light emitting diode (AMOLED) panel. 1 (λ) is applied to a pixel of a light emitting diode panel, comprising: a switch module that receives an image data signal and is controlled by a first scan signal; and a pseudo switch module coupled to the The switch module is controlled by a second scan signal, wherein the first and second scan signals have a predetermined phase 8 19 1259020 16029 twf.doc/g relationship; and the group-driven continuous light module is connected to the The open-group and the pseudo-switching mode w are offset by the coupling effect of the transition state of the first-scanning signal on the driving/light-emitting state of the driving/light-emitting group. The second inversion-delay is wherein the switch scans the signal of the pixel as described in item 1 of the patent application scope as the first-thickness, after %> After the signal, the three elements between the 唬 and an inversion-displacement signal are selected. The pixel described in item 10 of the patent application, wherein the switch = 1: the switch transistor 'has: receives the a source of the image data signal, receiving the gate of the first scan signal, - 极极. Price" 32 Please refer to the element mentioned in item 12 of the patent scope, wherein the pseudo-opening L-pseudo-pseudo-switching transistor has: secret to the switch, the second source, the receiving source The second scanning signal - the question pole, and the > and the pole. 14 · For the towel, please refer to the element mentioned in the 13th patent range, wherein the pseudo-opening: the glutinous crystal, having: connected to the a pseudo-opening secret and secret, and receiving - reference one of the pressures 15. According to the claim 12, the pseudo-opening J 杈 group receives the first scanning signal, and the The pseudo switch module comprises: a second pseudo switch transistor having: a source of one of the drains of the switch transistor 8 20 1259020 16029 twf.doc/g, receiving a gate of the first scan signal, and And a third dummy switching transistor having: a source coupled to one of the drains of the switching transistor, receiving a gate of the second scanning signal, and coupled to the second dummy switch One of the poles of the transistor is a drain. 16. The pixel according to claim 10, The driving/lighting module comprises: a driving transistor having: a source coupled to a power supply voltage, a gate coupled to the dummy switching module, and a drain; a storage capacitor coupled Between the power supply voltage and the gate of the driving transistor; and a light emitting element coupled between the drain of the driving transistor and a ground. 17. As described in claim 10 The pixel of claim 10, wherein the rising edge of the first scan signal is a step. 19. The ten-dimensional element, wherein the light-emitting diode panel is an active-drive organic light-emitting diode (AMOLED) panel. 8 21