Display driving device and display device including the same

Abstract

Provided is a display driver capable of accurately detecting the characteristics of a pixel of a display panel regardless of an amplifier offset, and a display device including the display driver. The display device includes a display panel and a display driver, the display panel includes pixels, and the display driver includes a sensing circuit configured to detect a pixel signal from the pixel. The sensing circuit includes a sensing amplifier configured to provide a first reference voltage to the pixel so that the pixel is programmed using the first reference voltage in a programming mode.

Description

Technical Field

[0001] The present disclosure relates to a display device, and more particularly, to a display driving device capable of accurately detecting characteristics of a panel and a display device including the display driving device. Background Art

[0002] Typically, a display device includes a display panel, a display driving device, a timing controller, and the like.

[0003] The display driving device converts digital image data provided from the timing controller into source signals and provides the source signals to the display panel. The display driving device can be integrated into a single chip, and a plurality of display driving devices can be configured by considering the size and resolution of the display panel.

[0004] In addition, the display driving device detects a signal of each pixel to compensate for the characteristics of the display panel, converts the signal into digital data, and provides the digital data to the timing controller.

[0005] A display driving device according to a conventional technique uses a source amplifier and a sense amplifier to detect a signal of each pixel. A problem with this conventional technique is that since the source amplifier and the sense amplifier have different offsets, the characteristics of the pixel cannot be accurately detected.

[0006] A problem with the conventional technology is that since an auto-zero circuit and a timing circuit are added to compensate for the offset of the amplifier, the complexity of the circuit increases.

[0007] Furthermore, the conventional technology has a problem in that, although an additional circuit for compensating for an offset is used, since the offset of the amplifier cannot be completely eliminated, the characteristics of the pixel cannot be accurately compensated. Summary of the invention

[0008] Various embodiments are directed to providing a display driving device capable of accurately detecting characteristics of pixels of a display panel regardless of an offset of an amplifier, and a display device including the display driving device.

[0009] In an embodiment, a display device may include a display panel and a display driving device, the display panel including pixels, the display driving device including a sensing circuit configured to detect a pixel signal from the pixel. The sensing circuit may include a sensing amplifier configured to provide a first reference voltage to the pixel, the sensing amplifier causing the pixel to be programmed using the first reference voltage in a programming mode.

[0010] In one embodiment, a display device includes a display driver including a sensing circuit configured to detect a pixel signal from a pixel of a display panel. The sensing circuit may include a sensing amplifier configured to provide a first reference voltage to the pixel, the sensing amplifier causing the pixel to be programmed using the first reference voltage in a programming mode.

[0011] In one embodiment, a display device may include: a display panel including pixels; a display driving device including a sensing circuit configured to detect pixel signals from the pixels, wherein the sensing circuit may include a sensing amplifier configured to provide a first reference voltage to the pixels, the sensing amplifier enabling the pixels to be programmed using the first reference voltage in a programming mode; and a controller configured to control the pixels and the sensing amplifier in an initialization mode in which the pixels are initialized, in a programming mode in which the pixels are programmed, and in a sensing mode in which the pixel signals are detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a circuit diagram of a display device according to an embodiment.

[0013] Figure 2 is a timing diagram of a display device according to an embodiment.

[0014] Figure 3 is a circuit diagram showing the operating state of a pixel in an initialization mode.

[0015] Figure 4 is a circuit diagram showing the operating state of a pixel in programming mode.

[0016] Figure 5 is a circuit diagram showing the operating state of a pixel in a sensing mode. DETAILED DESCRIPTION

[0017] Embodiments provide a display driving device capable of accurately detecting characteristics of pixels of a display panel regardless of an offset of an amplifier, and a display device including the display driving device.

[0018] In an embodiment, the sensing period may be defined as a period in which pixel characteristics are detected from the display panel 100. The display period may be defined as a period in which a source signal corresponding to digital image data is provided to the display panel 100.

[0019] In an embodiment, the sensing cycle can be divided into an initialization mode, a programming mode, and a sensing mode. The initialization mode can be defined as a task for initializing a pixel. The programming mode can be defined as a task for programming a pixel using a reference voltage of the sense amplifier 22 after the initialization mode. The sensing mode can be defined as a task for detecting a pixel signal from a pixel after the programming mode.

[0020] In an embodiment, the reference voltage V applied to the reference voltage terminal of the sense amplifier 22 is SENSE The second reference voltage VDATA0 may be applied as the first reference voltage VDATA1 in the programming mode and may be applied as the second reference voltage VDATA0 in the sensing mode. In this case, the second reference voltage VDATA0 may be set to a lower level than the first reference voltage VDATA1.

[0021] Figure 1 is a circuit diagram of a display device according to an embodiment.

[0022] Reference Figure 1 , the display device includes a display panel 100 and a display driving device 200 .

[0023] The display panel 100 includes data lines DL and gate lines (not shown), and has pixels P formed at intersections of the data lines DL and the gate lines. This embodiment shows a display device that implements pixels by using an organic light emitting diode (OLED). This embodiment shows a display device for detecting pixel signals through the data lines DL. For ease of description, Figure 1 Only one pixel is shown.

[0024] Each pixel P includes an OLED and a driving transistor DT. The driving transistor DT of the pixel P and the OLED may have different characteristics in terms of threshold voltage, mobility, etc. Although the same source signal is applied to the pixel, if the driving transistor DT of the pixel has different characteristics, the current flowing into the driving transistor DT of the pixel may be different.

[0025] In addition, the OLED and the driving transistor of the pixel of the display panel 100 may be degraded as driving time passes. Therefore, a deviation in characteristics may occur between pixels.

[0026] The present embodiment provides a display device capable of accurately detecting the characteristics of the pixel P of the display panel 100 regardless of the offsets of the source amplifier 12 and the sense amplifier 22 .

[0027] First, each pixel P of the display panel 100 includes an OLED, a driving transistor DT, first to fifth transistors T1 to T5, and a capacitor C ST .

[0028] The driving transistor DT causes the OLED to emit light by supplying current to the OLED. In response to a source signal applied from the driving circuit 10, current flowing into the driving transistor DT and the OLED may be controlled.

[0029] The first transistor T1 couples a source terminal of the driving transistor DT and the data line DL. The first transistor T1 may be turned on in a programming mode and a sensing mode.

[0030] The second transistor T2 is connected to the drain terminal of the driving transistor DT and the first power supply voltage terminal. The second transistor T2 can be turned on in the initialization mode and the sensing mode. The first power supply voltage VDD can be applied to the first power supply voltage terminal and can be used to initialize the pixel in the initialization mode.

[0031] The third transistor T3 couples the source terminal of the driving transistor DT and the OLED. The third transistor T3 may be turned off in the sensing period, and may be turned on in the display period.

[0032] The fourth transistor T4 couples the drain terminal of the driving transistor DT and the gate terminal of the driving transistor DT. The fourth transistor T4 may be turned on in the initialization mode and the programming mode.

[0033] Capacitor C ST The capacitor C has one end coupled to the gate terminals of the fourth transistor T4 and the driving transistor DT, and has the other end coupled to the fifth transistor T5. ST In the initialization mode, the capacitor C ST The capacitor C can store charges corresponding to the first power supply voltage VDD. ST Charges corresponding to the source signal may be stored during the display period.

[0034] The fifth transistor T5 is connected to the capacitor C ST The other end of and the initial voltage terminal. The fifth transistor T5 can be turned on in the initialization mode and the programming mode. The initial voltage VINI can be applied to the initial voltage terminal. The initial voltage VINI can be used to form a current path between the first power supply voltage terminal and the initialization voltage terminal in the initialization mode and the programming mode.

[0035] One end of the OLED is coupled to the third transistor T3, and the other end is coupled to the second power supply voltage terminal. The second power supply voltage VSS may be applied to the second power supply voltage terminal. In addition, the capacitor C ST The other end of and one end of the OLED are connected.

[0036] The initial voltage VINI may be set to a level lower than or equal to the second power voltage VSS, thereby forming a current path between the first power voltage terminal and the initialization voltage terminal in the initialization mode and the program mode.

[0037] The display driving device 200 includes a driving circuit 10 and a sensing circuit 20 .

[0038] In a display period, the driving circuit 10 receives digital image data from a timing controller (not shown), converts the digital image data into source signals, and provides the source signals to the display panel 100. The driving circuit 10 may include a latch, a digital-to-analog converter, and a source amplifier 12.

[0039] The sensing circuit 20 programs the pixel in the programming mode of the sensing period and detects the pixel signal from the pixel P in the sensing mode of the sensing period. The sensing circuit 20 may include a sensing amplifier 22. The sensing amplifier 22 may be connected to the data line DL, respectively. For ease of description, Figure 1 Only one sense amplifier 22 and one source amplifier 12 are shown.

[0040] In the programming mode, the sense amplifier 22 may provide the first reference voltage VDATA1 to the pixel P. The first node N1 and the second node N2 of the pixel P may be programmed using the first reference voltage VDATA1 provided from the sense amplifier 22. For example, the first node N1 of the pixel P may be programmed using the sum of the first reference voltage VDATA1 and the threshold voltage of the driving transistor DT. The second node N2 of the pixel P may be programmed using the first reference voltage VDATA1.

[0041] The sense amplifier 22 may operate as a unity gain amplifier in the programming mode. In the programming mode, the sense amplifier 22 may have a negative input stage (-) and an output stage coupled by turning on the third switch SW3, and may provide the data line DL of the pixel P with a first reference voltage VDATA1 applied to the positive input stage (+) of the sense amplifier 22.

[0042] In addition, the sense amplifier 22 can operate as an integrator in the sensing mode. In the sensing mode, the sense amplifier 22 can provide the data line DL of the pixel P with the second reference voltage VDATA0 applied to the positive input stage (+) of the sense amplifier 22, which can be connected in parallel to the feedback capacitor C by turning off the third switch SW3. FB , and can be operated as an integrator.

[0043] In this case, the second reference voltage VDATA0 may be set to a level lower than the first reference voltage VDATA1. In addition, the first switch SW1 may be turned on in the display period and may be turned off in the sensing period. The second switch SW2 and the third switch SW3 may be turned off in the display period and may be turned on or off according to the programming mode and the sensing mode in the sensing period.

[0044] In addition, the display device may include a controller (not shown) for controlling the first to fifth transistors T1 to T5 of the pixels P of the display panel 100 and the first to third switches SW1 to SW3 of the display driving device 200 .

[0045] The controller may initialize the first node N1 with the first power supply voltage VDD by turning off the first transistor T1 and the third transistor T3 of the pixel P and turning on the second transistor T2 , the fourth transistor T4 , and the fifth transistor T5 of the pixel P in an initialization mode.

[0046] The controller may program the first node N1 using the sum of the first reference voltage VDATA1 and the threshold voltage of the driving transistor DT by turning off the second and third transistors T2 and T3 of the pixel P and turning on the first, fourth, and fifth transistors T1, T4, and T5 of the pixel P in a programming mode.

[0047] The controller may control detection of the pixel signal by turning off the third transistor T3 , the fourth transistor T4 , and the fifth transistor T5 of the pixel P and turning on the first transistor T1 and the second transistor T2 of the pixel P in the sensing mode.

[0048] Figure 2 is a timing diagram of a display device according to an embodiment.

[0049] Reference Figure 1 and Figure 2 , during a sensing period for detecting characteristics of the display panel 100 , the display device may be divided and operated into an initialization mode, a programming mode, and a sensing mode.

[0050] In the initialization mode, the first scan signal SCAN1 and the second control signal EM2 are enabled, and the second scan signal SCAN2 and the first control signal EM1 are disabled. In addition, the first transistor T1 and the third transistor T3 of the pixel P are turned off, and the second transistor T2, the fourth transistor T4 and the fifth transistor T5 thereof are turned on. Therefore, in the initialization mode, the first node N1 may have the level of the first power supply voltage VDD.

[0051] In the programming mode, the first scan signal SCAN1 and the second scan signal SCAN2 are enabled, and the first control signal EM1 and the second control signal EM2 are disabled. In addition, the second switch SW2 and the third switch SW3 are turned on. In addition, the second transistor T2 and the third transistor T3 of the pixel P are turned off, and the first transistor T1, the fourth transistor T4 and the fifth transistor T5 thereof are turned on. Therefore, in the programming mode, the first node N1 can be programmed using the sum of the first reference voltage VDATA1 and the threshold voltage of the driving transistor DT.

[0052] In the sensing mode, the second scan signal SCAN2 and the second control signal EM2 are enabled, and the first scan signal SCAN1 and the first control signal EM1 are disabled. In addition, the second switch SW2 is turned on. The third switch SW3 provides the second reference voltage VDATA0 applied to the sense amplifier 22 to the data line DL of the pixel P, and is turned off. In this case, in the sensing mode, the switch SW3 can be turned off in the middle of the sensing mode so that the undesirable value is not integrated. In addition, the third transistor T3, the fourth transistor T4 and the fifth transistor T5 of the pixel P are turned off, and the first transistor T1 and the second transistor T2 thereof are turned on.

[0053] Therefore, in the sensing mode, the second node N2 has the level of the second reference voltage VDATA0. The gate of the driving transistor DT may be set to the sum of the first reference voltage VDATA1 and the threshold voltage of the driving transistor DT. The source of the driving transistor DT may be set to the second reference voltage VDATA0. Next, in the sensing mode, the sense amplifier 22 of the sensing circuit 20 may operate as an integrator, may integrate the current flowing into the data line DL, and may detect the pixel signal.

[0054] Figure 3 is a pixel circuit showing an operating state in an initialization mode.

[0055] Reference Figure 2 and Figure 3 In the initialization mode, a current path is formed between the first power supply voltage terminal and the initial voltage terminal by turning off the first transistor T1 and the third transistor T3 of the pixel P and turning on the second transistor T2, the fourth transistor T4 and the fifth transistor T5 of the pixel P.

[0056] The first node N1 may be initialized to a level of the first power voltage VDD through a current path formed between the first power voltage terminal and the initial voltage terminal.

[0057] Figure 4 is a pixel circuit showing an operating state in a programming mode.

[0058] Reference Figure 2 and Figure 4 In the programming mode, the pixel P may be programmed using the first reference voltage VDATA1 provided from the sense amplifier 22 by turning off the second transistor T2 and the third transistor T3 and turning on the first transistor T1 , the fourth transistor T4 , and the fifth transistor T5 .

[0059] In this case, the sensing circuit 20 may operate as a unity gain amplifier by turning on the second switch SW2 and the third switch SW3 , and may provide the pixel P with the first reference voltage VDATA1 .

[0060] Therefore, the first node N1 may be programmed using the sum of the first reference voltage VDATA1 and the threshold voltage of the driving transistor DT.

[0061] Figure 5 is a pixel circuit showing an operating state in a sensing mode.

[0062] Reference Figure 2 and Figure 5 , by turning off the third transistor T3, the fourth transistor T4, and the fifth transistor T5 and turning on the first transistor T1 and the second transistor T2, the pixel signal from the pixel P can be provided to the sensing circuit 20 through the data line DL. In this case, the sensing circuit 20 can operate as an integrator by turning on the second switch SW2 and turning off the third switch SW3, and can detect the pixel signal.

[0063] As described above, according to an embodiment, the pixel signal is detected after being programmed using the first reference voltage VDATA1 of the sense amplifier 22. Therefore, regardless of the offset of the sense amplifier 22 of the sensing circuit 20, the characteristics of the pixel P of the display panel 100 can be accurately detected.

[0064] Furthermore, according to the embodiment, since the characteristics of the pixels P of the display panel 100 can be accurately detected, the deviation between the characteristics of the pixels P due to degradation can be accurately compensated.

[0065] Furthermore, according to an embodiment, the sensing circuit 20 may be simplified because there is no need to add an auto-zero circuit and a timing circuit to compensate for the offset of the sense amplifier 22 .

[0066] Although various embodiments have been described above, those skilled in the art will appreciate that the described embodiments are merely exemplary. Therefore, the disclosure described herein should not be limited based on the described embodiments.

Claims

1. A display device, comprising: A display panel, including pixels; as well as The display driving device includes a sensing circuit configured to detect a pixel signal from the pixel, The sensing circuit includes a sensing amplifier configured to provide a first reference voltage to the pixel, so that the pixel is programmed using the first reference voltage in a programming mode. The sense amplifier transmits the first reference voltage to the data line of the pixel in the programming mode, and detects the pixel signal through the data line in the sensing mode after the programming mode.

2. The display device according to claim 1, wherein: The sense amplifier operates as a unity gain amplifier in the programming mode.

3. The display device according to claim 2, wherein: In the programming mode, the sense amplifier has a negative input stage and an output stage coupled, and the first reference voltage applied to a positive input stage of the sense amplifier is provided to a data line of the pixel.

4. The display device according to claim 1, wherein: The sense amplifier operates as an integrator in a sensing mode following the programming mode.

5. The display device according to claim 4, wherein: In the sensing mode, the sense amplifier operates as the integrator after providing the second reference voltage applied to a positive input stage of the sense amplifier to the data line of the pixel.

6. The display device according to claim 5, wherein: The second reference voltage is set to a level lower than the first reference voltage.

7. The display device according to claim 1, wherein: Each of the pixels comprises: Organic light-emitting diode OLED; a driving transistor configured to provide current to the OLED; a first transistor configured to connect a source terminal of the driving transistor and a data line; a second transistor configured to couple a drain terminal of the driving transistor and a first power supply voltage terminal; A third transistor configured to couple the source terminal of the drive transistor and the OLED; a fourth transistor configured to couple the drain terminal of the driving transistor and a gate terminal of the driving transistor; a capacitor configured to have one end coupled to the fourth transistor and the gate terminal and the other end coupled to the fifth transistor and configured to store charge; and the fifth transistor being configured to couple the other end of the capacitor and an initial voltage terminal, wherein the OLED has one end coupled to the third transistor and the other end coupled to the second power supply voltage terminal, and The other end of the capacitor is coupled to the one end of the OLED.

8. The display device according to claim 7, wherein: The level of the initial voltage of the initial voltage terminal is set to be equal to or lower than the level of the second power voltage of the second power voltage terminal.

9. The display device according to claim 7, wherein: In an initialization mode, a first node of the gate terminal is initialized to a first power supply voltage by turning off the first transistor and the third transistor and turning on the second transistor, the fourth transistor, and the fifth transistor.

10. The display device according to claim 9, wherein: In the programming mode after the initialization mode, the first node of the gate terminal is programmed using the sum of the first reference voltage and the threshold voltage of the driving transistor by turning off the second transistor and the third transistor and turning on the first transistor, the fourth transistor and the fifth transistor.

11. The display device according to claim 10, wherein: In the sensing mode following the programming mode, the pixel signal is detected by turning off the third transistor, the fourth transistor, and the fifth transistor and turning on the first transistor and the second transistor.

12. A display driving device, comprising: a sensing circuit configured to detect pixel signals from pixels of the display panel, The sensing circuit includes a sensing amplifier configured to provide a first reference voltage to the pixel, so that the pixel is programmed using the first reference voltage in a programming mode. The sense amplifier transmits the first reference voltage to the data line of the pixel in the programming mode, and detects the pixel signal through the data line in the sensing mode after the programming mode.

13. The display driving device according to claim 12, wherein: In the programming mode, the sense amplifier operates as a unity gain amplifier and provides the first reference voltage applied to an input stage of the sense amplifier to the data line of the pixel.

14. The display driving device according to claim 12, wherein: In a sensing mode following the programming mode, the sense amplifier provides a second reference voltage to a data line of the pixel and operates as an integrator.

15. The display driving device according to claim 14, wherein: The second reference voltage is set to a level lower than the first reference voltage.

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