Pixel driving circuit and display panel

Abstract

The present invention provides a pixel driving circuit and a display panel, wherein the pixel driving circuit comprises a driving transistor, wherein the driving transistor comprises an output terminal, an input terminal, and a control terminal, wherein the driving transistor is configured to generate a driving current in a light-emitting stage to drive the light-emitting device through the output terminal electrically connected to the light-emitting device; a compensation module is configured to detect and compensate for a threshold voltage of the driving transistor in the compensation stage; and an over-detection module is configured to adjust the threshold voltage detected and compensated by the compensation module in an over-detection stage after the compensation stage, wherein the threshold voltage detected and compensated by the compensation module is adjusted in the over-detection stage through the over-detection module, so that the threshold voltage detected by the compensation module is greater than the actual threshold voltage of the driving transistor, thereby compensating for the threshold voltage information lost due to parasitic capacitance and the like during compensation, thereby improving the compensation capability of the internal compensation circuit.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more particularly to a pixel driving circuit and a display panel. Background Art

[0002] AMOLED (Active Matrix / Organic Light Emitting Diode) displays offer advantages over traditional LCD displays, including a wider color gamut, wider viewing angles, higher contrast ratios, and faster response times. They are currently widely used in flagship smartphones, televisions, and other products from various brands. AMOLED displays use thin-film transistors (TFTs) to drive OLEDs (Organic Light-Emitting Diodes). However, because the threshold voltage (Vth) of the TFTs can shift, uneven brightness can occur.

[0003] To overcome the Vth offset problem, related art uses internal compensation and external compensation driving circuits for compensation. However, the internal compensation circuit may cause loss of detected Vth information due to parasitic capacitance and other factors, and thus its compensation capability is insufficient. Summary of the Invention

[0004] Embodiments of the present invention provide a pixel driving circuit, a driving method of the pixel driving circuit, and a display panel to solve the problem in the related art that the internal compensation circuit loses detected Vth information due to parasitic capacitance and other reasons, resulting in insufficient compensation capability.

[0005] To address the above problems, an embodiment of the present invention provides the following technical solution:

[0006] A pixel driving circuit for driving a light-emitting device to emit light, the pixel driving circuit comprising:

[0007] a driving transistor comprising an output terminal, an input terminal, and a control terminal, configured to generate a driving current in a light emitting phase to drive the light emitting device via the output terminal electrically connected to the light emitting device;

[0008] The compensation module is configured to detect and compensate the threshold voltage of the driving transistor during the compensation phase;

[0009] The over-detection module is configured to adjust the threshold voltage detected and compensated by the compensation module in an over-detection phase subsequent to the compensation phase.

[0010] In some embodiments, the compensation module includes:

[0011] A compensation transistor is provided, wherein the input terminal of the compensation transistor is electrically connected to the input terminal of the driving transistor, and the output terminal of the compensation transistor is electrically connected to the control terminal of the driving transistor. The control terminal of the compensation transistor is used to receive sensing signals.

[0012] In some embodiments, the over-detection module includes:

[0013] A first over-detection capacitor, the first terminal of which is electrically connected to the input terminal of the driving transistor, and the second terminal of which is used to receive the sensing signal.

[0014] In some embodiments, the control terminal of the driving transistor includes a first control terminal and a second control terminal, wherein the first control terminal receives a data signal to cause the driving transistor to generate a driving current, and the output terminal of the compensation transistor is electrically connected to the second control terminal.

[0015] In some embodiments, a storage module is further included, wherein the storage module includes:

[0016] A first storage capacitor is used to store the voltage at the first control terminal of the driving transistor. The first terminal of the first storage capacitor is electrically connected to the first control terminal of the driving transistor, and the second terminal of the first storage capacitor is electrically connected to the output terminal of the driving transistor.

[0017] The second storage capacitor is used to control the voltage of the second control terminal of the driving transistor. The first terminal of the second storage capacitor is electrically connected to the second control terminal of the driving transistor, and the second terminal of the second storage capacitor is electrically connected to the output terminal of the driving transistor.

[0018] In some embodiments, the overdetection module further includes a second overdetection capacitor, one end of which is electrically connected to the second control terminal of the driving transistor, and the other end of which is used for the sensing signal.

[0019] In some embodiments, the pixel driving circuit further includes an initialization module, the initialization module comprising:

[0020] A first initialization transistor has an input terminal for receiving a first initialization voltage, a control terminal for receiving the sensing signal, and an output terminal electrically connected to the output terminal of the driving transistor.

[0021] A second initialization transistor, wherein the input terminal of the second initialization transistor is used to receive a second initialization voltage, the control terminal of the second initialization transistor is used to receive the sensing signal, and the output terminal of the second initialization transistor is electrically connected to the first control terminal of the driving transistor.

[0022] Wherein, the first initialization voltage is greater than the second initialization voltage.

[0023] In some embodiments, the pixel driving circuit further includes:

[0024] A data transistor, wherein the input end of the data transistor is used to receive the data signal, the control end of the data transistor is used to receive a scan signal, and the output end of the data transistor is used to write the data signal to the first control end of the driving transistor.

[0025] In some embodiments, the pixel driving circuit further includes:

[0026] A light-emitting control transistor, wherein the control end of the light-emitting control transistor is used to receive a light-emitting control signal, the input end of the light-emitting control transistor is used to receive a first power supply signal, and the output end of the light-emitting control transistor is electrically connected to the input end of the driving transistor.

[0027] In some embodiments, the control terminal of the driving transistor includes a first control terminal, the first control terminal receiving a data signal to enable the driving transistor to generate a driving current, and the output terminal of the compensation transistor is electrically connected to the first control terminal; the pixel driving circuit further includes:

[0028] A first storage capacitor, wherein a first end of the first storage capacitor is electrically connected to the first control end of the driving transistor, and a second end of the first storage capacitor is electrically connected to the output end of the driving transistor.

[0029] This invention also provides a display panel including the pixel driving circuit described in any of the above embodiments.

[0030] Beneficial effect: The present invention adjusts the threshold voltage detected and compensated by the compensation module during the over-detection stage through the over-detection module, so that the threshold voltage detected by the compensation module is greater than the actual threshold voltage of the driving transistor, thereby compensating for the threshold voltage information lost due to parasitic capacitance and other reasons during compensation, thereby improving the compensation capability of the internal compensation circuit. Attached Figure Description

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0032] Attachment Figure 1 This is a schematic diagram of a pixel driving circuit according to an embodiment of the present invention;

[0033] Attachment Figure 2 This is a schematic diagram of a pixel driving circuit according to an embodiment of the present invention;

[0034] Attachment Figure 3 A timing diagram of a pixel driving circuit according to an embodiment of the present invention;

[0035] Attachment Figure 4 This is a schematic diagram of a pixel driving circuit without a detection module according to an embodiment of the invention;

[0036] Attachment Figure 5 for Figure 4 A schematic diagram of the voltage change in the pixel driving circuit when the compensation transistor is turned off;

[0037] Attachment Figure 6 This is a schematic diagram of a pixel driving circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0039] One embodiment of the present invention provides a pixel driving circuit to solve the problem of V detection being affected by parasitic capacitance and other factors in the internal compensation circuit. th Information loss leads to insufficient compensation capacity.

[0040] like Figure 1 and Figure 2 As shown, the pixel driving circuit is used to drive the light-emitting device LED to emit light. The pixel driving circuit includes a driving transistor T1, a compensation module 200, and an over-detection module 300.

[0041] The driving transistor T1 includes an output end, an input end, and a control end. The control end of the driving transistor T1 receives a data signal Data, and the input end of the driving transistor T1 receives a power signal. The output end of the driving transistor T1 is electrically connected to the light-emitting device LED to generate a driving circuit under the control of the data signal Data, thereby driving the light-emitting device LED to emit light.

[0042] The compensation module 200 is electrically connected to the second control terminal. The compensation module 200 detects the threshold voltage of the driving transistor T1 in the compensation phase t2 , thereby compensating for the threshold voltage of the driving transistor T1 .

[0043] After the compensation phase t2 , the over-detection phase t3 is entered. In the over-detection phase t3 , the over-detection module 300 adjusts the threshold voltage detected and compensated by the compensation module 200 so that the detected threshold voltage is greater than the actual threshold voltage of the driving transistor T1 .

[0044] In this embodiment, the over-detection module 300 adjusts the threshold voltage detected and compensated by the compensation module 200 in the over-detection phase t3, so that the threshold voltage detected by the compensation module 200 is greater than the actual threshold voltage of the driving transistor T1, thereby compensating for the loss of V due to parasitic capacitance and other reasons during compensation. th information to improve the compensation capability of the internal compensation circuit.

[0045] The present application will be described below through a specific circuit structure.

[0046] In some embodiments, the control terminal of the driving transistor T1 includes a first control terminal and a second control terminal. The pixel circuit further includes a light-emitting control transistor T6, a data transistor T5, a storage module 400, and an initialization module 100. The control terminal of the light-emitting control transistor T6 receives a light-emitting control signal EM, the input terminal of the light-emitting control transistor T6 receives a first power supply signal EVDD, and the output terminal of the light-emitting control transistor T6 is electrically connected to the input terminal of the driving transistor T1.

[0047] The input terminal of the data transistor T5 receives a data signal Data, the control terminal of the data transistor T5 receives a scan signal Scan, and the output terminal of the data transistor T5 is electrically connected to the first control terminal of the driving transistor T1 to write the data signal Data to the first control terminal of the driving transistor T1. Thus, the driving transistor T1 generates a driving current under the control of the data signal Data, driving the LED to emit light.

[0048] The compensation module 200 includes a compensation transistor T4, the input terminal of which is electrically connected to the input terminal of the driving transistor T1, and the output terminal of which is electrically connected to the control terminal of the driving transistor T1. The control terminal of the compensation transistor T4 is used to receive a sensing signal Sense.

[0049] The overdetection module 300 includes a first overdetection capacitor C1, the first end of which is electrically connected to the input terminal of the driving transistor T1, and the second end of which receives the sensing signal Sense.

[0050] The storage module 400 includes a first storage capacitor C. st and the second storage capacitor C th The first storage capacitor C st The first storage capacitor C is used to store the voltage at the first control terminal of the driving transistor T1. st The first terminal is electrically connected to the first control terminal of the driving transistor T1, and the first storage capacitor C st The second terminal is electrically connected to the output terminal of the driving transistor T1. The second storage capacitor C th The second storage capacitor C is used to control the voltage at the second control terminal of the driving transistor T1. th The first terminal is electrically connected to the second control terminal of the driving transistor T1, and the second storage capacitor C th The second terminal is electrically connected to the output terminal of the driving transistor T1.

[0051] The initialization module 100 includes a first initialization transistor T2 and a second initialization transistor T3. The input terminal of the first initialization transistor T2 receives a first initialization voltage V. init The control terminal of the first initialization transistor T2 receives the sensing signal Sense, and the output terminal of the first initialization transistor T2 is electrically connected to the output terminal of the driving transistor T1. The input terminal of the second initialization transistor T3 receives the second initialization voltage V. ref The control terminal of the second initialization transistor T3 is used to receive the sensing signal Sense, and the output terminal of the second initialization transistor T3 is electrically connected to the first control terminal of the driving transistor T1. The first initialization voltage V... init Greater than the second initial voltage V ref .

[0052] like Figure 3As shown, the pixel driving circuit includes an initialization stage t1, a compensation stage t2, an overdetection stage t3, a writing stage t4, and an emission stage t5.

[0053] During initialization phase t1, the light emission control signal EM is high, the sensing signal Sense is high, and the scanning signal Scan is low. The light emission control transistor T6, the driving transistor T1, the first initialization transistor T2, and the second initialization transistor T3 are turned on. The first power supply signal EVDD is written to points d and b, the first initialization signal is written to point g (the first control terminal of the driving transistor T1), and the second initialization signal is written to point s (the output terminal of the driving transistor T1). Therefore, the first storage capacitor C... st The second storage capacitor C th And the over-detection capacitor begins to charge.

[0054] During compensation phase t2, the light emission control signal EM is low, the sensing signal Sense is high, and the scanning signal Scan is low. The driving transistor T1, the first initialization transistor T2, and the second initialization transistor T3 are turned on. Because the second initialization transistor T3 and the driving transistor T1 are turned on, the voltage at point b continuously decreases until V... gs +αV bs =V th Among them, V gs V is the voltage difference between the first control terminal and the output terminal of the driving transistor T1. bs α is the voltage difference between the second control terminal and the output terminal of the driving transistor T1, and is a constant. Since the first control terminal and the output terminal of the driving transistor T1 respectively receive the first initialization voltage V... init and the second initialization voltage V re f, therefore the V gs =V ref –V init Therefore, V th =V gs +αV bs =V ref –V init +αV bs The transformation yields αV bs =V th –V ref +V init Due to the αV bs Stored in the second storage capacitor C th Therefore, the second storage capacitor C thIn the compensation phase t2, the threshold voltage V of the driving transistor T1 is stored. th The initialization module 100 applies a first initialization voltage V to the first control terminal and the output terminal. init and the second initialization voltage V ref , thereby completing the compensation for the driving transistor T1.

[0055] During the detection phase t3, the light emitting control signal EM, the sensing signal Sense and the scanning signal Scan are all at low levels. st The overdetection capacitor was charged during the initialization phase t1 and the compensation phase t2, so the compensation transistor T4 was in the conducting state during the overdetection phase t3. The sensing signal Sense changed from a high potential to a low potential. Due to the coupling effect of the first overdetection capacitor C1, the potentials at points d and b both decreased. Since the compensation transistor T4 separates point b from the first overdetection capacitor C1, and point d is directly connected to the first overdetection capacitor C1, the potential at point d decreased faster than the potential at point b. The potentials at points d and b changed from equal to unequal, thus increasing the voltage difference between the two points, i.e., |V db | increases. Therefore, I bd The current flowing through points d and b also increases. However, compared to the potential changes at points d and b, the potential changes at points g and s are relatively small. Based on formula V... gs +αV bs =V th It can be seen that ΔV th =ΔV gs +αΔV bs , where ΔV th is the change in the threshold voltage of the driving transistor T1, ΔV gs ΔV is the change in voltage difference between point g and point s. bs This represents the change in pressure difference between point b and point s. Therefore, ΔV th Mainly affected by ΔV bs Since the voltage at point s remains unchanged, the second initialization voltage V ref Therefore, the ΔV th Mainly affected by ΔV b The impact. It can be seen that during the compensation phase t2, the second storage capacitor C... th The threshold voltage of the driving transistor T1 has been detected and stored, so the ΔV this the change in threshold voltage further detected due to the influence of the first over-detection capacitor C1, that is, the second storage capacitor C th The detected threshold voltage is affected by the first overdetection capacitor C1, which can increase or decrease the voltage. Therefore, the overdetection capacitor adjusts the ΔV. b The size of the second storage capacitor C is such that... th The stored threshold voltage is equal to the actual threshold voltage of the driving transistor T1 and the threshold voltage lost during the compensation process, thus achieving complete compensation of the actual threshold voltage of the driving transistor T1.

[0056] like Figure 4 and Figure 5 As shown, when the pixel driving circuit is not provided with the over-detection capacitor, under different threshold voltages, the V gs The changes are different. Specifically, when the threshold voltage is based on 0V, the threshold voltage is negatively biased (V... th =-1.5v), ΔV b When the threshold voltage is positively biased, V increases. th =1.5v), ΔV b Therefore, based on this rule, we can choose the appropriate ΔV b To adjust the second storage capacitor C th The detected threshold voltage.

[0057] During the writing phase t4, the light emission control signal EM is low, the sensing signal Sense is low, and the scanning signal Scan is high. The data transistor T5 and the driving transistor T1 are turned on. The data signal Data is written to point g, i.e., the data voltage V. data Write the first control terminal of the driving transistor T1 and write the first storage capacitor C st Charge it.

[0058] During the light-emitting stage t5, the light-emitting control signal EM is high, the sensing signal Sense is low, and the scanning signal Scan is low. The light-emitting control transistor T6 and the driving transistor T1 are turned on. The driving transistor T1 is activated by the data voltage V. data A driving current is generated under control, causing the LED to emit light.

[0059] like Figure 6 As shown, in some embodiments, in order to increase ΔV b The rate of change is also provided with a second over-detection capacitor C2. One end of the second over-detection capacitor C2 is electrically connected to the sensing signal Sense line, and the other end of the second over-detection capacitor C2 is electrically connected to the second control terminal.

[0060] This invention also provides a display panel, including the pixel driving circuit and gate driving circuit described in any of the above embodiments. The gate driving circuit is used to provide the scan signal Scan.

[0061] The pixel driving circuit is used to drive the light-emitting device LED to emit light. The pixel driving circuit includes a driving transistor T1, a compensation module 200, and an over-detection module 300.

[0062] The driving transistor T1 includes an output end, an input end, and a control end. The control end of the driving transistor T1 receives a data signal Data, and the input end of the driving transistor T1 receives a power signal. The output end of the driving transistor T1 is electrically connected to the light-emitting device LED to generate a driving circuit under the control of the data signal Data, thereby driving the light-emitting device LED to emit light.

[0063] The compensation module 200 is electrically connected to the second control terminal. The compensation module 200 detects the threshold voltage of the driving transistor T1 in the compensation phase t2 , thereby compensating for the threshold voltage of the driving transistor T1 .

[0064] After the compensation phase t2 , the over-detection phase t3 is entered. In the over-detection phase t3 , the over-detection module 300 adjusts the threshold voltage detected and compensated by the compensation module 200 so that the detected threshold voltage is greater than the actual threshold voltage of the driving transistor T1 .

[0065] In this embodiment, the display panel adjusts the threshold voltage detected and compensated by the compensation module 200 during the overdetection stage t3 via the overdetection module 300, so that the threshold voltage detected by the compensation module 200 is greater than the actual threshold voltage of the driving transistor T1, thereby compensating for the V lost due to parasitic capacitance and other reasons during compensation. th information to improve the compensation capability of the internal compensation circuit.

[0066] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A pixel driving circuit for driving a light-emitting device to emit light, characterized in that: The pixel driving circuit comprises: A driving transistor, comprising an output terminal, an input terminal, and a control terminal, configured to generate a driving current in a light emitting phase to drive the light emitting device through the output terminal electrically connected to the light emitting device; A compensation module, configured to detect and compensate for a threshold voltage of the driving transistor in a compensation phase; an over-detection module configured to adjust the threshold voltage detected and compensated by the compensation module in an over-detection phase after the compensation phase; The compensation module comprises: a compensation transistor, wherein an input terminal of the compensation transistor is electrically connected to the input terminal of the driving transistor, an output terminal of the compensation transistor is electrically connected to the control terminal of the driving transistor, and the control terminal of the compensation transistor is used to receive a sensing signal; The over-detection module comprises: a first over-detection capacitor, wherein a first end of the first over-detection capacitor is electrically connected to the input end of the driving transistor, and a second end of the first over-detection capacitor is used to receive the sensing signal; The control end of the driving transistor includes a first control end and a second control end, the first control end receives a data signal to enable the driving transistor to generate a driving current, the output end of the compensation transistor is electrically connected to the second control end; the input end of the driving transistor receives a power signal; Also included is a storage module, the storage module comprising: a first storage capacitor, used to store the voltage of the first control terminal of the driving transistor, wherein the first terminal of the first storage capacitor is electrically connected to the first control terminal of the driving transistor, and the second terminal of the first storage capacitor is electrically connected to the output terminal of the driving transistor; A second storage capacitor is used to control the voltage of the second control terminal of the driving transistor, wherein the first terminal of the second storage capacitor is electrically connected to the second control terminal of the driving transistor, and the second terminal of the second storage capacitor is electrically connected to the output terminal of the driving transistor.

2. The pixel driving circuit according to claim 1, characterized in that: The over-detection module further includes a second over-detection capacitor, one end of the second over-detection capacitor is electrically connected to the second control end of the driving transistor, and the other end of the second over-detection capacitor receives the sensing signal.

3. The pixel driving circuit according to claim 2, characterized in that: The pixel driving circuit further includes an initialization module, and the initialization module includes: a first initialization transistor, wherein an input terminal of the first initialization transistor is used to receive a first initialization voltage, a control terminal of the first initialization transistor is used to receive the sensing signal, and an output terminal of the first initialization transistor is electrically connected to the output terminal of the driving transistor; a second initialization transistor, wherein an input terminal of the second initialization transistor is used to receive a second initialization voltage, a control terminal of the second initialization transistor is used to receive the sensing signal, and an output terminal of the second initialization transistor is electrically connected to the first control terminal of the driving transistor; Wherein, the first initialization voltage is greater than the second initialization voltage.

4. The pixel driving circuit according to claim 1, characterized in that: The pixel driving circuit further includes: A data transistor, wherein the input end of the data transistor is used to receive the data signal, the control end of the data transistor is used to receive a scan signal, and the output end of the data transistor is used to write the data signal to the first control end of the driving transistor.

5. The pixel driving circuit according to claim 1, characterized in that: The pixel driving circuit further includes: A light emitting control transistor, wherein the control end of the light emitting control transistor is used to receive a light emitting control signal, the input end of the light emitting control transistor is used to receive a first power supply signal, and the output end of the light emitting control transistor is electrically connected to the input end of the driving transistor.

6. A display panel, characterized in that: The invention comprises the pixel driving circuit as described in any one of claims 1 to 5.

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