TWI413102B - Display apparatus and gamma voltage generator - Google Patents

Abstract

A display apparatus and a gamma voltage generator are provided. The gamma voltage generator includes a gamma reference voltage generating unit and a voltage divider unit. The gamma reference voltage generating unit receives a frame rate signal. When the frame rate of a display panel is a first frequency represented by the frame rate signal, the gamma reference voltage generating unit is outputting a plurality of first gamma reference voltages. When the frame rate of a display panel is a second frequency represented by the frame rate signal, the gamma reference voltage generating unit is outputting a plurality of second gamma reference voltages. The voltage divider unit is coupled to the gamma reference voltage generating unit to generate a plurality of first gamma voltages according to the first gamma reference voltages or generate a plurality of second gamma voltages according to the second gamma reference voltages.

Description

Display device and gamma voltage generator

The present invention relates to a display device and a gamma voltage generator, and more particularly to a display device and a gamma voltage generator for preventing flickering of a picture.

In recent years, with the rapid development of semiconductor technology, portable electronic products and flat panel display products have also emerged. Among the many types of flat panel displays, liquid crystal displays (LCDs) have become the mainstream of display products based on their low voltage operation, no radiation scattering, light weight and small size.

For example, a liquid crystal display is applied to a portable electronic product such as a notebook (NB). In order to effectively reduce the power consumption of the battery of the notebook computer in the liquid crystal display, Intel has proposed a set of SDRRS (seamless dynamic refresh rate switching) technology, so that the liquid crystal display of the notebook computer displays the static picture state, the display panel The frame rate of the picture is switched from 60 Hz to 40 Hz which originally displays the dynamic picture. In this way, the liquid crystal display can effectively reduce the power consumption of the battery of the notebook computer, thereby achieving the purpose of power saving.

However, since the resolution of today's display panels is getting higher and higher, so that the pixel update rate is 60 Hz, the charging time of the pixels will be insufficient, so that the corresponding target storage charge will not be charged; painting When the picture update rate is 40 Hz, the charging time of the pixels increases, so that the corresponding target storage charge can be charged. In view of this, under the condition that the gamma voltage does not change, when the notebook computer starts the SDRRS technology to switch the screen update rate of the display panel from 60 Hz to 40 Hz (that is, switch from the dynamic picture to the static picture), or When switching from 40Hz to 60Hz (that is, switching from a still picture to a dynamic picture), the charging time at the picture update rate of 60Hz (T60=1/60) is different from the charging time of the picture update rate of 40Hz. (T40=1/40), so that the stored charge (Q60) of the pixel at a picture update rate of 60 Hz is also different from the stored charge (Q40) of the picture at a picture update rate of 40 Hz. In this way, when the notebook computer starts the SDRRS technology, it will cause a difference in the brightness of the two switching pictures, which causes the picture to flicker.

The present invention provides a gamma voltage generator that maintains the same gamma curve of a display panel at different picture update rates.

The present invention provides a display device that prevents flickering of a screen when a screen update rate is switched.

The present invention proposes a gamma voltage generator suitable for a display device having a display panel. The gamma voltage generator includes a gamma reference voltage generating unit and a voltage dividing unit. The gamma reference voltage generating unit receives the picture update rate signal. The gamma reference voltage generating unit outputs a plurality of first gamma reference voltages when the picture update rate signal indicates that the picture update rate of the display panel is the first frequency. When the screen update rate signal indicates that the screen update rate of the display panel is the second When the frequency. The gamma reference voltage generating unit outputs a plurality of second gamma reference voltages. The voltage dividing unit is coupled to the gamma reference voltage generating unit to generate a plurality of first gamma voltages according to the first gamma reference voltages or to generate a plurality of second gamma voltages according to the second gamma reference voltages.

In an embodiment of the present invention, the gamma curves formed when the first gamma voltages of the display panel are at the first frequency of the display panel are the same as the update rates of the second gamma voltages on the display panel. The gamma curve formed at the second frequency.

In an embodiment of the invention, the first gamma reference voltage of the portion is the same as the portion of the second gamma reference voltage corresponding to the same grayscale value.

In an embodiment of the invention, each of the first gamma reference voltage and the second gamma reference voltage corresponding to the same grayscale value is obtained when the grayscale value approaches a maximum grayscale value or a minimum grayscale value. The difference will be smaller.

In an embodiment of the invention, the first gamma voltage of the portion is equal to the portion of the second gamma voltage corresponding to the same grayscale value.

In an embodiment of the invention, when the grayscale value approaches the maximum grayscale value or the minimum grayscale value, the difference between each first gamma voltage and the second gamma voltage corresponding to the same grayscale value will The smaller.

In an embodiment of the invention, the first frequency is 60 Hz and the second frequency is 40 Hz.

The present invention further provides a display device including a display panel, a timing controller, and a gamma voltage generator as described above. The timing controller generates a screen update rate signal according to the screen update rate of the display panel. The gamma voltage generator is coupled to the timing controller.

In an embodiment of the invention, the display panel is normally white.

In an embodiment of the invention, the display panel is normally black.

Based on the above, the display device and the gamma voltage generator of the present invention have a gamma voltage generator respectively providing a first gamma voltage and a second gamma voltage at different picture update rates, and the display panel is generated by the gamma voltage. Driven by the first gamma voltage or the second gamma voltage provided by the device. Thereby, the gamma curve of the display panel at different screen update rates can be maintained the same, thereby preventing the screen from flickering.

The above described features and advantages of the present invention will be more apparent from the following description.

1 is a system diagram of a display device in accordance with an embodiment of the present invention. Referring to FIG. 1 , in the embodiment, the display device 100 includes a timing controller 110 , a gate driver 120 , a gamma voltage generator 130 , a source driver 140 , and a display panel 150 . The timing controller 110 receives the display data DS, and determines the screen update rate of the display panel 150 based on the display data DS to generate the screen update rate signal FRS according to the screen update rate of the display panel 150. Moreover, the timing controller 110 controls the gate driver 120 to output the scan signal SC according to the display data DS to turn on each column of pixels (not shown) on the display panel 150.

The gamma voltage generator 130 outputs more according to the picture update rate signal FRS One first gamma voltage VG1 or a plurality of second gamma voltages VG2. The source driver 140 is controlled by the timing controller 110 to output the driving voltage VD corresponding to the display data DS to the turned-on pixels on the display panel 150 according to the first gamma voltage VG1 or the second gamma voltages VG2 (not Painted). The gamma curve formed by the first gamma voltage VG1 when the picture update rate of the display panel 150 is the first frequency (for example, 60 Hz) is the same as the picture update rate of the second gamma voltage VG2 on the display panel 150. A gamma curve formed at a second frequency (eg, 40 Hz).

2 is a system diagram of the gamma voltage generator 130 of FIG. 1 in accordance with an embodiment of the present invention. Referring to FIG. 2, in the embodiment, the gamma voltage generator 130 includes a gamma reference voltage generating unit 210 and a voltage dividing unit 220. The gamma reference voltage generating unit 210 receives the picture update rate signal FRS. When the picture update rate signal FRS indicates that the picture update rate of the display panel 150 is the first frequency, the gamma reference voltage generation unit 210 outputs a plurality of first gamma reference voltages VR1. When the picture update rate signal FRS indicates that the picture update rate of the display panel 150 is the second frequency, the gamma reference voltage generating unit 210 outputs a plurality of second gamma reference voltages VR2.

The voltage dividing unit 220 is coupled to the gamma reference voltage generating unit 210. When the voltage dividing unit 220 receives the first gamma reference voltages VR1, the first gamma voltages VG1 are generated according to the first gamma reference voltages VR1. That is, the voltage dividing unit 220 divides the first gamma reference voltages VR1, and the divided voltages serve as the first gamma voltages VG1. When the voltage dividing unit 220 receives the second gamma reference voltages VR2, the second gamma voltages VG2 are generated according to the second gamma reference voltages VR2. That is, the voltage dividing unit 220 divides the second gamma reference voltages VR2, and the divided voltages serve as the second gamma voltages VG2.

The gamma reference voltage generating unit 210 can be a memory component to store the first gamma reference voltage VR1 and the second gamma reference voltage VR2. Moreover, the voltage dividing unit 220 may be composed of a plurality of series connected resistors to divide the first gamma reference voltage VR1 and the second gamma reference voltage VR2.

FIG. 3 is a gamma graph in which a first gamma voltage is applied to different picture update rates. Referring to FIG. 3, in the embodiment, the display panel 150 displays normal white, and the curve 310 is a gamma curve formed by the first gamma voltage VG1 when the display panel 150 is displayed at 60 Hz. 320 is a gamma curve formed when the first gamma voltage VG1 is displayed on the display panel 150 at 40 Hz. Since the gamma curve 310 and the gamma curve 320 partially overlap, the portions do not overlap, that is, the display effect of the first gamma voltage VG1 is different when the screen update rate is different. In order to maintain the gamma curve unchanged when the picture update rate is different, the second gamma voltage VG2 is additionally designed.

Looking at the grayscale value 32, the curve 310 corresponds to a luminance of 70. When the luminance is 70, the grayscale value corresponding to the curve 320 is 33. According to the above, the driving voltage VD corresponding to the grayscale value 32 of the second gamma voltage VG2 is equal to the driving voltage VD of the first gamma voltage VG2 corresponding to the grayscale value 33. The driving voltage VD corresponding to the other grayscale values in the second gamma voltage VG2 can also be determined in the above manner, and will not be described herein. Therefore, when the picture update rate is 60 Hz, the gamma voltage generator 130 outputs a plurality of first gamma The gamma voltage generator 130 outputs a plurality of second gamma voltages VG2 when the picture update rate is 40 Hz. Thereby, the gamma curve displayed by the display panel can be maintained on the curve 310 when the screen update rate is changed to avoid flickering of the screen.

In addition, as shown in FIG. 3, when the grayscale value approaches the grayscale value of 0, the difference between the gamma curve 310 and the gamma curve 320 becomes smaller or even the same, that is, the grayscale value approaches 63. (ie, the maximum grayscale value), the difference between each first gamma voltage VG1 and the second gamma voltage VG2 corresponding to the same grayscale value will be smaller. When the grayscale value approaches the grayscale value 63, the difference between the gamma curve 310 and the gamma curve 320 will also become smaller or even the same, that is, the grayscale value approaches 0 (ie, the minimum grayscale value). The difference between each first gamma voltage VG1 and the second gamma voltage VG2 corresponding to the same grayscale value is also smaller.

Since the first gamma voltage VG1 is generated by dividing the first gamma reference voltage VR1, and the second gamma voltage VG2 is generated by dividing the second gamma reference voltage VR2, the first gamma reference voltage VR1 is corresponding to The difference between the second gamma reference voltage VR2 of the same gray scale value becomes smaller or even zero when the gray scale value approaches 63 or 0. Table 1 is a set of first gamma reference voltage VR1 and a set of second gamma reference voltage VR2 that are actually measured, wherein the same column represents the same grayscale value.

As shown in Table 1, a portion of the first gamma reference voltage VR1 is the same as the portion of the second gamma reference voltage VR2 corresponding to the same grayscale value, and the same portion is closer to the maximum grayscale value and minimum. Grayscale value. Similarly, part of the first gamma voltage VG1 is also the same as the portion of the second gamma voltage VG2 corresponding to the same gray level value, and the same portion is also close to the maximum gray. The order value (ie 63) and the minimum gray level value (ie 0).

It should be noted that the above embodiment is an example in which the display panel 150 normally displays white color. In other embodiments, the display panel 150 can display black as an example, and the curve 320 is a first gamma voltage VG1. The gamma curve formed when the panel 150 is displayed at 60 Hz, and the curve 310 is a gamma curve formed when the first gamma voltage VG1 is displayed at 40 Hz by the display panel 150. Further, the second gamma voltage VG2 can be determined by referring to the above description, and will not be described again.

In summary, its gamma voltage generator is under different picture update rates. The first gamma voltage and the second gamma voltage are respectively provided, and the display panel is driven according to the first gamma voltage or the second gamma voltage provided by the gamma voltage generator. Thereby, the gamma curve of the display panel at different screen update rates can be maintained the same, thereby avoiding flickering of the screen.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧ display device

110‧‧‧Sequence Controller

120‧‧‧gate driver

130‧‧‧Gamma Voltage Generator

140‧‧‧Source Driver

150‧‧‧ display panel

210‧‧‧Gamma Reference Voltage Generation Unit

220‧‧‧Voltage unit

310, 320‧‧‧ Curve

DS‧‧‧Display information

FRS‧‧‧ screen update rate signal

VD‧‧‧ drive voltage

VR1, VR2‧‧‧ gamma reference voltage

VG1, VG2‧‧‧ gamma voltage

1 is a system diagram of a display device in accordance with an embodiment of the present invention.

2 is a schematic diagram of the system of the gamma voltage generator of FIG. 1 according to an embodiment of the invention.

FIG. 3 is a gamma graph in which a first gamma voltage is applied to different picture update rates.

130‧‧‧Gamma Voltage Generator

210‧‧‧Gamma Reference Voltage Generation Unit

220‧‧‧Voltage unit

FRS‧‧‧ screen update rate signal

VR1, VR2‧‧‧ gamma reference voltage

VG1, VG2‧‧‧ gamma voltage

Claims (10)

A gamma voltage generator is applicable to a display device having a display panel, comprising: a gamma reference voltage generating unit that receives a picture update rate signal, and when the picture update rate signal indicates a picture update rate of the display panel At a first frequency, a plurality of first gamma reference voltages are output, and when the picture update rate signal indicates that the picture update rate of the display panel is a second frequency, a plurality of second gamma reference voltages are output; a voltage dividing unit coupled to the gamma reference voltage generating unit to generate a plurality of first gamma voltages according to the first gamma reference voltages, or to generate a plurality of second gamma according to the second gamma reference voltages Ma voltage. The gamma voltage generator of claim 1, wherein the first gamma voltage is the same as the second gamma curve formed when the picture update rate of the display panel is the first frequency. The gamma curve is a gamma curve formed when the picture update rate of the display panel is the second frequency. The gamma voltage generator of claim 1, wherein the portion of the first gamma reference voltage is the same as the portion of the second gamma reference voltages corresponding to the same grayscale value. The gamma voltage generator of claim 1, wherein each of the first gamma reference voltages is the same when the grayscale value approaches a maximum grayscale value or a minimum grayscale value The difference in the second gamma reference voltage of the gray scale value will be smaller. The gamma voltage generator of claim 1, wherein the portions of the first gamma voltages are the same as the second gamma voltages Should be part of the same grayscale value. The gamma voltage generator according to claim 1, wherein each of the first gamma voltages corresponds to the same gray when the grayscale value approaches a maximum grayscale value or a minimum grayscale value. The difference in the second gamma voltage of the order value will be smaller. The gamma voltage generator of claim 1, wherein the first frequency is 60 Hz and the second frequency is 40 Hz. A display device includes: a display panel; a timing controller that generates a picture update rate signal according to a picture update rate of the display panel; and a gamma voltage generator as described in claim 1 of the patent application, coupled The timing controller. The display device of claim 8, wherein the display panel is normally white. The display device of claim 8, wherein the display panel is normally black.