TWI767327B - Method for improving brightness adjustment accuracy of display panel, OLED display, and mobile electronic device - Google Patents

Abstract

The present invention mainly discloses a method for improving the brightness adjustment precision of a display panel, which is applied to a display driver chip, and the display driver chip can generate N×M pieces of said N×M which are correspondingly transmitted to an OLED display panel. N pixel emission control signals of the pixel circuit unit, and each pixel emission control signal has T signal periods and T low-level widths within a picture period of one frame of display data. In the case of applying the method of the present invention, after receiving a brightness adjustment signal, the display driver chip can only perform a low-level width adjustment on at least one of the pixel lighting control signals, thereby extending or shortening T/2 the low level width. That is, only half of the low-level widths of the pixel light-emitting control signal in the picture period of one frame of display data are controlled, so as to improve the brightness adjustment accuracy.

Description

Method for improving brightness adjustment accuracy of display panel, OLED display, and mobile electronic device

The present invention relates to the technical field of OLED displays, in particular to a method for improving the brightness adjustment precision of a display panel applied in a gate driving circuit of an OLED display.

It is known that Organic Light-Emitting Diode (OLED) has the advantages of self-luminescence, high brightness, high contrast, wide viewing angle, power consumption, and high reaction rate, so it has been widely used in self-luminescence. The production of display panels includes active OLED (ie, AMOLED) display panels and passive OLED (ie, PMOLED) display panels.

FIG. 1 shows a block diagram of a conventional OLED display. As shown in FIG. 1, the OLED display 1a includes: an OLED display panel 11a, a gate (column) driving circuit 12a, a source (row) driving circuit 13a, and a display controller 14a. The OLED display panel 11a includes N×M OLED sub-pixels 111a, N×M pixel circuit units 112a, M source driving lines 11Sa, and N gate driving lines 11Ga. In more detail, each gate driving line 11Ga is coupled to M pixel circuit units 112a along the column direction, and each source driving line 11Sa is coupled to N pixel circuit units 112a along the row direction.

FIG. 2 shows the operation timing diagram of the vertical synchronization signal and the pixel lighting control signal used in the conventional OLED display. As shown in FIG. 1 , each of the pixel circuit units 112a is coupled to a scan signal Scan and a pixel emission control signal EM transmitted from the gate driving circuit 12a. The pixel lighting control signal EM is a PWM signal, so that a display driver chip including the gate driving circuit 12a and the source driving circuit 13a can dynamically adjust the duty cycle of the PWM signal by adjusting the duty ratio of the PWM signal. The light-emitting luminance (ie, gray scale) of each of the OLED sub-pixels 111a. In addition, the conventional technology usually completes the modulation of the duty ratio of the pixel light-emitting control signal EM by changing the low-level width of the pixel light-emitting control signal EM.

For example, the OLED sub-pixel 111a is adjusted to the light-emitting brightness of the OLED sub-pixel 111a with a full-DC pixel light-emitting control signal (ie, the duty cycle is 100%) within a frame period of displaying data, then the OLED sub-pixel The luminous intensity of 111a is 255. As shown in FIG. 2 , if the pixel light-emitting control signal EM has T signal periods in the picture period of one frame of display data, and the low-level width of the pixel light-emitting control signal EM in each signal period is At W1, the duty cycle (Duty cycle) of the pixel light emission control signal EM is 75%. At this time, the light emission luminance of the OLED sub-pixel 111a can be adjusted to 191 using the pixel light emission control signal EM having a duty ratio of 75%.

It is easy to infer that, as shown in FIG. 2 , if the pixel light-emitting control signal EM has T signal periods in the picture period of one frame of display data, and further, the pixel light-emitting control signal EM has T signal periods in each signal period. When the low level width is extended from W1 to W1a, the duty ratio of the pixel light-emitting control signal EM is 50%. At this time, the light emission luminance of the OLED sub-pixel 111a can be adjusted to 127 using the pixel light emission control signal EM having a duty ratio of 50%. On the other hand, if the low level width of the pixel emission control signal EM in each signal period is further extended from W1a to W1b, the duty cycle of the pixel emission control signal EM is 25%. At this time, the light emission luminance of the OLED sub-pixel 111a can be adjusted to 64 using the pixel light emission control signal EM having a duty ratio of 25%.

It should be noted that the conventional display driver chip including the gate driver circuit 12a and the source driver circuit 13a further includes a brightness calculating unit for calculating a brightness value according to a digital brightness value (Digital Brightness Value, DBV) to calculate the degree of brightness adjustment required for the OLED sub-pixel 111a. Therefore, after receiving a brightness adjustment signal sent by the brightness calculation unit, as shown in FIG. 2 , the gate driving circuit 12a of the display driving chip generates the corresponding pixel lighting control signals EM(1~n) in rows. . Therefore, it can be understood that when performing brightness adjustment, the width of the low level of the pixel light emission control signal EM is adjusted with the precision of “line”. For example, the duty cycle of EM(1) is 25% for adjusting the luminance of the OLED sub-pixel 111a to 64, and the duty cycle of EM(1+j) is 50% for adjusting the OLED sub-pixel 111a to 64. The light emission brightness of the pixel 111a is adjusted to 127.

When performing brightness adjustment, the low-level width of the pixel light-emitting control signal EM with T signal periods in one frame of display data is modulated line by line. Therefore, when setting the pixel light-emitting control of the j line When the signals EM all have different low-level widths, the total low-level widths included in all the pixel light-emitting control signals EM are T×j. As can be seen from FIG. 2 , in the prior art, the duty ratio of the pixel light-emitting control signal EM is changed by simultaneously changing the widths of all T low levels in the T signal periods. However, practical experience shows that with the increase of the signal period T and the number of lines j, the low-level width of the pixel light-emitting control signal EM will limit the precision allowed for modulation within the picture period of one frame of display data.

It can be seen from the above description that a novel PWM signal generating circuit is urgently needed in the art.

The main purpose of the present invention is to provide a method for improving the brightness adjustment accuracy of a display panel, which is applied to a display driver chip, which can generate N×M for correspondingly transmitted to an OLED display panel included in the display driver chip. N pixel light-emitting control signals of each of the pixel circuit units, and each pixel light-emitting control signal has T signal periods and T low-level widths within a picture period of one frame of display data. In the case of applying the method of the present invention, after receiving a brightness adjustment signal, the display driver chip can only perform a low-level width adjustment on at least one of the pixel lighting control signals, thereby extending or shortening T/2 the low level width. That is, only half of the low-level widths of the pixel light-emitting control signal in the picture period of one frame of display data are controlled, so as to improve the brightness adjustment accuracy.

In order to achieve the above object, the present invention proposes an embodiment of the method for improving the brightness adjustment accuracy of a display panel, which is applied to an OLED display including at least one display driver chip and an OLED display panel; wherein, the OLED display The panel includes N×M OLED sub-pixels, N×M pixel circuit units, M source driving lines, and N gate driving lines, N and M are both positive integers, and the pixel leakage current The compensation method includes the following steps:

generating N pixel light-emitting control signals for correspondingly transmitting to the N×M pixel circuit units, and each pixel light-emitting control signal has T signal periods within a frame period of one frame of display data, and T low widths; and

A low-level width adjustment is performed on at least one of the pixel light-emitting control signals according to a brightness adjustment signal, thereby extending or shortening the low-level width by T/2.

In one embodiment, the T signal periods include T/2 odd-numbered signal periods and T/2 even-numbered signal periods, and the low-level width adjustment is performed for T/2 odd-numbered signal periods. The included T/2 low-level widths are extended or shortened.

In one embodiment, the T signal periods include T/2 odd-numbered signal periods and T/2 even-numbered signal periods, and the low-level width adjustment is performed for T/2 of the even-numbered signal periods. The included T/2 low-level widths are extended or shortened.

In one embodiment, when performing the low-level width adjustment, T/2 of the T low-level widths are randomly selected, thereby extending or shortening the T/2 low-level widths.

The present invention also provides an OLED display, which includes at least one display driver chip and an OLED display panel, and the OLED display panel includes N×M OLED sub-pixels, N×M pixel circuit units, and M source drivers. line, and N gate driving lines; wherein, N and M are both positive integers, and the display driving chip is used to execute a method for improving the brightness adjustment accuracy of a display panel; the method for improving the brightness adjustment accuracy of a display panel Include the following steps:

generating N pixel light-emitting control signals for correspondingly transmitting to the N×M pixel circuit units, and each pixel light-emitting control signal has T signal periods within a frame period of one frame of display data, and T low widths; and

A low-level width adjustment is performed on at least one of the pixel light-emitting control signals according to a brightness adjustment signal, thereby extending or shortening the low-level width by T/2.

In one embodiment, the T signal periods include T/2 odd-numbered signal periods and T/2 even-numbered signal periods, and the low-level width adjustment is performed for T/2 odd-numbered signal periods. The included T/2 low-level widths are extended or shortened.

In one embodiment, the T signal periods include T/2 odd-numbered signal periods and T/2 even-numbered signal periods, and the low-level width adjustment is performed for T/2 of the even-numbered signal periods. The included T/2 low-level widths are extended or shortened.

In one embodiment, when performing the low-level width adjustment, T/2 of the T low-level widths are randomly selected, thereby extending or shortening the T/2 low-level widths.

The present invention also provides an information processing device having the OLED display of the present invention as described above.

In one embodiment, the information processing device is an electronic device selected from the group consisting of a smart phone, a smart watch, a smart bracelet, a tablet computer, a notebook computer, an all-in-one computer, and an access control device.

In order to enable your examiners to further understand the structure, characteristics, purpose, and advantages of the present invention, drawings and detailed descriptions of preferred embodiments are attached as follows.

The present invention mainly discloses a method for improving the brightness adjustment accuracy of a display panel, which is applied to a display driving chip including a gate driving circuit and a source driving circuit, and the gate driving circuit can be generated for corresponding transmission N pixel light-emitting control signals to the N×M pixel circuit units included in an OLED display panel, and each of the pixel light-emitting control signals has T signal periods within a frame period of one frame of display data , and each signal cycle contains a low level width. In the case of applying the method of the present invention, after receiving a brightness adjustment signal, the display driver chip can only perform a low-level width adjustment on at least one of the pixel lighting control signals, thereby extending or shortening T/2 the low level width. That is, only half of the low-level widths of the pixel light-emitting control signal in the picture period of one frame of display data are controlled, so as to improve the brightness adjustment accuracy.

FIG. 3 shows a block diagram of an OLED display to which a method for improving the brightness adjustment accuracy of a display panel of the present invention is applied. As shown in FIG. 3, the OLED display 1 includes: an OLED display panel 11, a gate (column) driving circuit 12, a source driving (row) circuit 13, and a display controller 14, wherein the gate driving The circuit 12 and the source driver circuit 13 can be integrated into a single display driver chip. Moreover, it can be seen from FIG. 3 that the OLED display panel 11 includes: N×M OLED sub-pixels 111 , N×M pixel circuit units 112 , M source driving lines 11S, and N gate driving lines 11G, Both N and M are positive integers. In more detail, each gate driving line 11G is coupled to the M pixel circuit units 112 along a first direction, and each source driving line 11S is along a mutually orthogonal to the first direction. The N pixel circuit units 112 are coupled in the second direction. To describe in more detail, each of the pixel circuit units 112 is simultaneously coupled to a scan signal Scan and a pixel emission control signal EM transmitted from the gate driving circuit 12 .

FIG. 4 shows a flowchart of a method for improving the brightness adjustment accuracy of a display panel according to the present invention. As shown in FIG. 3 and FIG. 4 , the method flow first executes step S1 : generating N pixel emission control signals EM for correspondingly transmitting to the N×M pixel circuit units 112 , and each pixel The light emission control signal EM has T signal periods and T low-level widths in a picture period of one frame of display data. It is worth noting that the display driver chip including the gate driver circuit 12 and the source driver circuit 13 also includes a brightness calculating unit (Brightness calculating unit) to be based on a digital brightness value (Digital Brightness Value, DBV) Then, the degree of brightness adjustment required for the OLED sub-pixel 111 is calculated. Therefore, in step S2 of the method flow, the gate driving circuit 12 in the display driving chip performs a low-level operation on at least one of the pixel lighting control signals EM according to a brightness adjustment signal transmitted from the brightness calculation unit The level width is adjusted, thereby extending or shortening the width of the low level by T/2. It should be understood that after the low level width is extended or shortened, the duty cycle of the pixel emitting control signal EM is changed, so that the brightness adjustment function of the selected OLED sub-pixel 111 can be performed.

5A, 5B and 5C show the operation timing diagrams of the vertical synchronization signal and the pixel light emission control signal used in the OLED display of the present invention. According to the design of the present invention, the pixel light-emitting control signal EM has T signal periods and T low-level widths in a picture period of one frame of display data. For example, FIG. 5A shows that the pixel light emission control signal EM has four signal periods and four low-level widths. In one embodiment, when the digital luminance data is changed from DBV1 to DBV2, after receiving the luminance adjustment signal transmitted by the luminance calculation unit, the gate driving circuit 12 performs a control on T/2 of the odd-numbered signal cycles for T/2. /2 of the low-level widths are extended or shortened, so as to complete a low-level width adjustment for at least one of the pixel lighting control signals EM. For example, as shown in FIG. 5A , the original low-level width W1 of the pixel light-emitting control signal EM in an odd-numbered signal period is extended to W2 . In this way, only half of the low-level width of the pixel light-emitting control signal EM can be controlled within the picture period of one frame of display data, so as to improve the brightness adjustment accuracy.

In another embodiment, when the digital brightness data is changed from DBV1 to DBV2, after receiving the brightness adjustment signal transmitted by the brightness calculation unit, the gate driving circuit 12 performs the adjustment to T/2 of the even signal periods contained in the T/2 of the low-level widths are extended or shortened, thereby completing a low-level width adjustment for at least one of the pixel light-emitting control signals EM. For example, as shown in FIG. 5B , the original low-level width W1 of the pixel light-emitting control signal EM in an even-numbered signal period is extended to W2 . In this way, only half of the low-level width of the pixel light-emitting control signal EM can be controlled within the picture period of one frame of display data, so as to improve the brightness adjustment accuracy.

Further, in other possible embodiments, when the digital brightness data is changed from DBV1 to DBV2, after receiving the brightness adjustment signal transmitted by the brightness calculation unit, the gate driving circuit 12 switches from the T low level widths Among them, T/2 are randomly selected, and T/2 low-level widths are further extended or shortened, thereby completing a low-level width adjustment for at least one of the pixel light-emitting control signals EM. For example, as shown in FIG. 5C , for the pixel light-emitting control signal EM having four signal periods in the picture period of one frame of display data, after the low-level width adjustment is completed, it is in The original low-level width W1 in the first and fourth signal cycles is extended to W2. In this way, only half of the low-level width of the pixel light-emitting control signal EM can be controlled within the picture period of one frame of display data, so as to improve the brightness adjustment accuracy.

In this way, the above has completely and clearly explained a method for improving the brightness adjustment accuracy of the display panel of the present invention; and, from the above, it can be known that the present invention has the following advantages:

(1) The present invention discloses a method for improving the brightness adjustment accuracy of a display panel, which is applied to a display driver chip, and the display driver chip can generate N×M pieces for correspondingly transmitted to an OLED display panel. The N pixel light-emitting control signals of the pixel circuit unit, and each pixel light-emitting control signal has T signal periods and T low-level widths in a picture period of one frame of display data. In the case of applying the method of the present invention, after receiving a brightness adjustment signal, the display driver chip can only perform a low-level width adjustment on at least one of the pixel lighting control signals, thereby extending or shortening T/2 the low level width. That is, only half of the low-level widths of the pixel light-emitting control signal in the picture period of one frame of display data are controlled, so as to improve the brightness adjustment accuracy.

(2) The present invention also provides an OLED display, which includes at least one display driver chip and an OLED display panel, and the display driver chip is used to implement the aforementioned method of the present invention for improving the brightness adjustment accuracy of the display panel.

(3) The present invention also provides an information processing device having the OLED display of the present invention as described above. Moreover, the information processing device is an electronic device selected from the group consisting of smart phones, smart watches, smart bracelets, tablet computers, notebook computers, all-in-one computers, and access control devices.

It must be emphasized that the above-mentioned disclosure in this case is a preferred embodiment, and any partial changes or modifications originating from the technical ideas of this case and easily inferred by those who are familiar with the art are within the scope of the patent of this case. category of rights.

To sum up, regardless of the purpose, means and effect of this case, it shows that it is completely different from the conventional technology, and its first invention is suitable for practical use, and it does meet the requirements of a patent for invention. Society is to pray for the best.

1a: OLED display 11a: OLED display panel 111a: OLED sub-pixel 112a: pixel circuit unit 11Sa: source drive line 11Ga: gate drive line 12a: Gate drive circuit 13a: Source driver circuit 14a: Display Controller 1: OLED display 11: OLED display panel 111: OLED sub-pixel 112: Pixel circuit unit 11S: source drive line 11G: Gate drive line 12: Gate drive circuit 13: Source driver circuit 14: Display Controller S1: Generate N pixel light-emitting control signals to be transmitted to the N×M pixel circuit units correspondingly, and each of the pixel light-emitting control signals has T signals in a picture period of one frame of display data period and T low-level widths S2: Perform a low-level width adjustment on at least one of the pixel light-emitting control signals according to a brightness adjustment signal, thereby extending or shortening T/2 the low-level widths

1 is a block diagram of a conventional OLED display; 2 is a working timing diagram of a vertical synchronization signal and a pixel lighting control signal used in a conventional OLED display; 3 is a block diagram of an OLED display to which a method for improving the brightness adjustment accuracy of a display panel of the present invention is applied; 4 is a flowchart of a method for improving the brightness adjustment accuracy of a display panel according to the present invention; 5A is a working timing diagram of a vertical synchronization signal and a pixel lighting control signal used in the OLED display of the present invention; FIG. 5B is a working timing diagram of the vertical synchronization signal and the pixel lighting control signal used in the OLED display of the present invention; and FIG. 5C is a working timing diagram of the vertical synchronization signal and the pixel lighting control signal used in the OLED display of the present invention.

S1: Generate N pixel light-emitting control signals to be transmitted to the N×M pixel circuit units correspondingly, and each of the pixel light-emitting control signals has T signals in a picture period of one frame of display data period and T low-level widths

S2: Perform a low-level width adjustment on at least one of the pixel light-emitting control signals according to a brightness adjustment signal, thereby extending or shortening T/2 the low-level widths

Claims (10)

A method for improving the brightness adjustment precision of a display panel, which is applied in an OLED display including at least one display driver chip and an OLED display panel; wherein, the OLED display panel includes N×M OLED sub-pixels, N×M M pixel circuit units, M source driving lines, and N gate driving lines, N and M are both positive integers, and the method for improving the brightness adjustment accuracy of a display panel includes the following steps: generating a corresponding The N pixel light-emitting control signals are transmitted to the N×M pixel circuit units, and each pixel light-emitting control signal has T signal periods and T low voltages within the picture period of one frame of display data. a flat width; and performing a low-level width adjustment on at least one of the pixel light-emitting control signals according to a brightness adjustment signal, thereby extending or shortening the T/2 low-level widths. The method for improving the brightness adjustment accuracy of a display panel according to claim 1, wherein the T signal periods include T/2 odd-numbered signal periods and T/2 even-numbered signal periods, and the low-level width is executed During the adjustment, the T/2 low-level widths contained in the T/2 odd-numbered signal periods are extended or shortened. The method for improving the brightness adjustment accuracy of a display panel according to claim 1, wherein the T signal periods include T/2 odd-numbered signal periods and T/2 even-numbered signal periods, and the low-level width is executed During the adjustment, the T/2 low level widths contained in T/2 even signal periods are extended or shortened. The method for improving the brightness adjustment accuracy of a display panel according to claim 1, wherein when performing the low-level width adjustment, T/2 are randomly selected from among the T low-level widths, thereby extending the Or shorten the width of the low level by T/2. An OLED display includes at least one display driver chip and an OLED display panel, and the OLED display panel includes N×M OLED sub-pixels, N×M pixel circuit units, M source drive lines, and N A gate driving line; wherein, N and M are both positive integers, and the display driving chip is used to execute a method for improving the brightness adjustment accuracy of a display panel; the method for improving the brightness adjustment accuracy of the display panel includes the following steps: generating N pixel light-emitting control signals for correspondingly transmitting to the N×M pixel circuit units, and each pixel light-emitting control signal has T signal periods within a frame period of one frame of display data, and T low-level widths; and performing a low-level width adjustment on at least one of the pixel lighting control signals according to a brightness adjustment signal, thereby extending or shortening the T/2 low-level widths. The OLED display of claim 5, wherein the T signal periods include T/2 odd-numbered signal periods and T/2 even-numbered signal periods, and the low-level width adjustment is performed for T/2 The T/2 low-level widths contained in the odd-numbered signal periods are extended or shortened. The OLED display of claim 5, wherein the T signal periods include T/2 odd-numbered signal periods and T/2 even-numbered signal periods, and the low-level width adjustment is performed for T/2 The T/2 low-level widths contained in the even-numbered signal periods are extended or shortened. The OLED display according to claim 5, wherein when performing the low-level width adjustment, T/2 are randomly selected from among the T low-level widths, thereby extending or shortening T/2 all the low-level widths. the low level width. An information processing device having the OLED display according to any one of claim 5 to claim 8. The information processing device according to claim 9, which is an electronic device selected from the group consisting of smart phones, smart watches, smart bracelets, tablet computers, notebook computers, all-in-one computers, and access control devices .

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