TWI408650B - Display, driving apparatus and driving method thereof - Google Patents

Abstract

A driving apparatus for driving a backlight unit to provide a light source is described. The driving apparatus includes an image signal processing unit, a luminance compensation unit and an inverter. The image signal processing unit receives image signals and outputs a duty cycle data according to the image signals. The luminance compensation unit, coupled to the image signal processing unit, receives and counts the duty cycle data. When the duty cycle data is during a span of a set duty cycle, luminance of the light source is changed from the first luminance to a second luminance, and the luminance compensation unit outputs a luminance compensation signal. The inverter, coupled between the luminance compensation unit and the backlight unit, receives the luminance compensation signal and proceeds the luminance compensation to the backlight unit according to the luminance compensation signal for changing the second luminance to the first luminance.

Description

Display and its driving device and driving method

The present invention relates to a display, a driving device and a driving method thereof, and more particularly to a display capable of providing a light source of stable brightness, a driving device thereof and a driving method.

Flat Panel Display (FPD) has the characteristics of light, thin, short and small, and has become the mainstream of current displays. In particular, among many flat panel displays, liquid crystal displays (LCDs) have high spatial utilization efficiency, low power consumption, no radiation, and low electromagnetic interference, and are well received by consumers. In the past, liquid crystal displays were mostly used to display still images. However, with the advancement of multimedia technology, the demand for displaying dynamic pictures is more remarkable.

Generally, a liquid crystal display is mainly composed of a backlight unit and a liquid crystal display panel. The early backlight unit only continuously provided the light source required for the liquid crystal display panel. Therefore, when the liquid crystal display displays a dynamic picture, a double image will be generated due to the persistence of the human eye. In order to solve the problem of smear, a backlight unit that provides a light source by Dynamic Backlight (DBL) has been developed, that is, the backlight unit is capable of giving light sources of different brightness according to the screen displayed by the liquid crystal display panel.

FIG. 1A is a schematic diagram of a duty cycle-time curve of a conventional backlight unit using dynamic backlight technology. FIG. 1B is a schematic diagram of a brightness-time curve of a conventional backlight unit using dynamic backlight technology. Referring to FIG. 1A and FIG. 1B simultaneously, the backlight unit can provide a light source with maximum brightness (B ₁₀₀ ') when the duty cycle of the backlight unit reaches 100%. On the other hand, if the duty cycle of the backlight unit is reduced to 20%, a light source having a low luminance (B ₂₀ ') can be provided. At present, in order to improve the contrast of dynamic images, the brightness of the light source provided by the backlight unit is often lowered, that is, the duty cycle is set to 20% or lower.

However, if the backlight unit is in a low duty cycle for a long time (as in the case of 20% as shown in FIG. 1A), the temperature of the lamp unit of the backlight unit will decrease. In more detail, since the lamp cannot be operated at the optimum operating temperature, the luminous efficiency of the lamp is lowered. As shown in FIG. 1B, when the long-time working period is at 20% of the light source, the actual brightness (ie, the second brightness) will be lower than the expected brightness (ie, the first brightness). This will result in a poor match between the image signal and the brightness of the light source, which degrades the display effect of the dynamic picture.

In view of this, the present invention provides a driving device that can provide a light source that stabilizes brightness.

The present invention further provides a display comprising the above-described driving device to provide a light source of stable brightness, thereby enabling good display of moving images.

The present invention further provides a driving method that can compensate for brightness when a brightness reduction of a backlight unit occurs.

Based on the above, the present invention provides a driving device for driving a backlight unit to emit a light source. The driving device comprises: an image signal processing unit, Brightness compensation unit and inverter. The image signal processing unit receives the image signal and outputs the work cycle data according to the image signal. The brightness compensation unit is coupled to the image signal processing unit, and the brightness compensation unit receives and counts the work cycle data. When the work cycle data is in the set work cycle for a period of time, the light source changes from the first brightness to the second brightness, and the brightness compensation unit outputs Brightness compensation signal. The inverter is coupled between the brightness compensation unit and the backlight unit, and the inverter receives the brightness compensation signal and performs brightness compensation on the backlight unit according to the brightness compensation signal to change the second brightness to the first brightness.

Based on the above, the present invention further provides a display comprising a driving device and a display panel. The driving device is configured to drive the backlight unit to emit a light source, and the display panel is electrically connected to the driving device. The driving device comprises: an image signal processing unit, a brightness compensation unit and an inverter. The image signal processing unit receives the image signal and outputs the work cycle data according to the image signal. The brightness compensation unit is coupled to the image signal processing unit, and the brightness compensation unit receives and counts the work cycle data. When the work cycle data is in the set work cycle for a period of time, the light source changes from the first brightness to the second brightness, and the brightness compensation unit outputs Brightness compensation signal. The inverter is coupled between the brightness compensation unit and the backlight unit, and the inverter receives the brightness compensation signal and performs brightness compensation on the backlight unit according to the brightness compensation signal to change the second brightness to the first brightness.

Based on the above, the present invention further provides a driving method for driving a backlight unit to emit a light source. This driving method includes the following steps. First, an image signal is received and a duty cycle data is output according to the image signal. Then, receive and count work cycle data, when the work cycle The data is in a set working period for a period of time, the light source changes from a first brightness to a second brightness, and a brightness compensation signal is output. Thereafter, the brightness compensation signal is received and the backlight unit is subjected to brightness compensation according to the brightness compensation signal to change the second brightness to the first brightness.

In an embodiment of the present invention, the driving method further comprises: using an image signal processing unit to count the image signals to obtain a gray scale distribution data, and outputting the work period data according to the gray scale distribution data.

In an embodiment of the invention, the driving method further comprises receiving and counting the duty cycle data and the output brightness compensation signal by using a brightness compensation unit, wherein the brightness compensation unit comprises a work cycle statistics unit and a lookup table unit. The work cycle statistics unit receives the work cycle data and counts the number or time of occurrence of the set work cycle in the work cycle data. When the number of times or time when the set duty cycle occurs exceeds a predetermined value, the look-up unit finds the brightness compensation signal.

In an embodiment of the invention, the brightness compensation signal is a duty cycle compensation signal.

In an embodiment of the invention, the period of time during which the duty cycle data is in the set duty cycle is, for example, 5 minutes to 10 minutes.

In an embodiment of the invention, the setting work cycle is, for example, between 10% and 30%.

The driving device of the present invention employs a brightness compensation unit to compensate a duty cycle for an inverter that controls the backlight unit to enable the backlight unit to provide a light source of stable brightness. Applying the driving device to the display and using the driving method can improve the dynamic display effect of the display panel and solve the past The problem of reduced brightness due to backlight units operating at low duty cycles.

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

2A is a block diagram of a display in accordance with a preferred embodiment of the present invention. Referring to FIG. 2A , the display device 200 includes a driving device 210 and a display panel 220 , wherein the display panel 220 is electrically connected to the driving device 210 . The display panel 220 may be a liquid crystal panel or any type of panel that requires a light source, which is not limited herein.

2B is a block diagram of the driving device of FIG. 2A. Referring to FIG. 2B, the driving device 210 has a backlight unit 218 to provide a light source. The driving device 210 includes an image signal processing unit 212, a brightness compensation unit 214, and an inverter 216. The image signal processing unit 212 receives an image signal IS (IS) and outputs a duty cycle data Duty to the brightness compensation unit 214 according to the image signal IS. The brightness compensation unit 214 is coupled to the image signal processing unit 212. The brightness compensation unit 214 receives and counts the duty cycle data Duty. When the duty cycle data Duty is in a set duty cycle for a period of time, the light source changes from a first brightness to a first At the same time, the brightness compensation unit 214 outputs a light compensation signal LCS (Light Compensation Signal, LCS). The inverter 216 is coupled between the brightness compensation unit 214 and the backlight unit 218. The inverter 216 receives the brightness compensation signal LCS and performs brightness compensation on the backlight unit 218 according to the brightness compensation signal LCS to change the second brightness to the second brightness. One brightness.

The set working period mentioned above is, for example, 10% to 30%, and the period of the duty cycle data Duty is in the set working period, for example, 5 minutes to 10 minutes. In addition, the brightness compensation signal LCS is, for example, a duty cycle compensation signal. In more detail, after the duty cycle data Duty is in the set duty cycle for 20%, the actual brightness is lower than the expected brightness. The brightness of the actual light source of the backlight unit 218 can be improved by compensating the duty cycle by the brightness compensation signal LCS, that is, the duty cycle compensation signal.

In addition, please refer to FIG. 2A and FIG. 2B simultaneously, the image signal processing unit 212 counts the image signal IS to obtain a gray scale distribution data (not shown), and outputs the duty cycle data Duty according to the gray scale distribution data. In more detail, when the display panel 220 displays a screen according to the image signal IS, if the gray scale distribution data of the image signal IS is biased toward a higher gray scale, the representative display screen is brighter, that is, the backlight unit 218 You don't have to be too bright. In other words, the duty cycle data Duty can be adjusted corresponding to the gray scale distribution data to lower the brightness of the light source provided by the backlight unit 218, and vice versa.

In the above, the backlight unit 218 of the driving device 210 can determine the light sources of different brightness according to the screen displayed by the display panel 220, so that the screen presented by the display panel 220 has a high dynamic contrast, and the backlight unit 218 can be effectively saved. Power consumption.

However, when the backlight unit 218 continues to provide a light source of lower brightness at a low duty cycle, the temperature of the lamp of the backlight unit 218 may decrease, resulting in the actual brightness of the emitted light source being lower than the expected brightness. However, the above drive The moving device 210 utilizes the brightness compensation unit 214 to adjust the duty cycle, thereby solving this problem.

Referring to FIG. 2B, the brightness compensation unit 214 can include a duty cycle statistics unit 214a and a lookup table unit 214b. The work cycle statistics unit 214a may receive the work cycle data Duty and count the number or time during which the work cycle data continues to appear in the duty cycle data Duty. When the number of times or time during which the set duty cycle occurs exceeds a predetermined value, the lookup unit 214b finds the brightness compensation signal LCS.

In more detail, in an embodiment, it is assumed that the set duty cycle is 20%, and when the duty cycle data Duty is in the set work cycle 20% is 5-10 minutes, that is, the backlight unit 218 is considered to be in a low duty cycle for a long time. It is a low-intensity light source. At this time, the look-up table unit 214b can establish a lookup table (LUT) according to the relationship between the time when the set working period continues to appear and the brightness compensation signal LCS, so that the respective brightness compensation signals LCS can be obtained according to different working cycles. And supplied to the inverter 216.

In another embodiment, the duty cycle statistics unit 214a may receive and count the number of consecutive occurrences of the set duty cycle in the duty cycle data Duty. The lookup unit 214b may establish a lookup table (LUT) according to the relationship between the number of times the set duty cycle continues to occur and the brightness compensation signal LCS to determine how many duty cycles to compensate for the inverter 216. For example, assuming that the set duty cycle is 20%, the duty cycle counting unit 214a performs a count once it detects that the duty cycle is 20%, or about 20% (i.e., a numerical interval). When the count value obtained by continuous counting exceeds a predetermined threshold, it is considered Light unit 218 is in a low duty cycle. At this point, the lookup unit 214b is caused to find out how many duty cycles should be compensated to the inverter 216.

In the above, the brightness compensation unit 214 can output the brightness compensation signal LCS to the inverter 216 by the look-up unit 214b to perform brightness compensation on the backlight unit 218. As such, the light source provided by the backlight unit 218 can be changed to the brightness that it should have. The process of luminance compensation will be described below by way of example.

3A is a schematic diagram showing a duty cycle-time curve of a driving device according to a preferred embodiment of the present invention. FIG. 3B is a schematic diagram of a brightness-time curve of a driving device according to a preferred embodiment of the present invention. Referring to FIG. 3A and FIG. 3B, when the duty cycle of the backlight unit 218 reaches 100%, the backlight unit 218 can provide a light source with maximum brightness (B ₁₀₀ ). On the other hand, if the duty cycle of the backlight unit 218 is reduced to 20%, a light source having a low luminance (B ₂₀ ) can be provided at this time. As shown in the previous FIG. 1B, when the backlight unit 218 is at a low duty cycle of 20% for a long time, the supplied light source will be changed from the first brightness to the second brightness.

However, referring to FIG. 2B, FIG. 3A and FIG. 3B, according to the brightness compensation process, the brightness compensation unit 214 outputs the brightness compensation signal LCS to the inverter 216 (as shown in FIG. 3A), and the inverter 216 is based on The brightness compensation signal LCS compensates the backlight unit 218 for a duty cycle, thereby changing the second brightness to the first brightness, as shown in FIG. 3B. As such, the backlight unit 218 can provide a light source of stable brightness even at a low duty cycle.

4 is a flow chart of a driving method according to a preferred embodiment of the present invention. Referring to FIG. 2A, FIG. 2B, FIG. 3A, FIG. 3B and FIG. 4, the driving method is used to drive a backlight unit 218 to emit a light source. In this embodiment, the driving method can use the driving device 310 to drive the backlight Unit 218 emits a light source for the purpose. The following describes the driving method in detail.

First, in step S402, an image signal IS is received and a duty cycle data Duty is output according to the image signal IS. In detail, the driving method of the embodiment further includes using an image signal processing unit 212, and after receiving the image signal IS, the image signal processing unit 212 can count the grayscale value of the image signal IS. The distribution further obtains the gray scale distribution data (not shown) corresponding to the image signal IS. Then, the image signal processing unit 212 outputs the corresponding duty cycle data Duty according to the gray scale distribution data. When the display panel 220 displays a dynamic image by using a continuous image signal, the image signal processing unit 212 sequentially generates duty cycle data Duty corresponding to the image signals to determine the time when the backlight unit 218 is turned on.

Next, in step S404, the duty cycle data Duty is received and counted. When the duty cycle data Duty is in a set working cycle for a period of time, the light source changes from a first brightness to a second brightness, and outputs a brightness compensation signal. LCS. The driving method of this embodiment further includes using a brightness compensation unit 214 to receive and count the duty cycle data Duty and the output brightness compensation signal LCS. The detailed configuration of the brightness compensation unit 214 and the process of outputting the brightness compensation signal LCS have been described above and will not be repeated here.

Then, in step S406, the brightness compensation signal LCS is received and the backlight unit 218 is subjected to brightness compensation according to the brightness compensation signal LCS to change the second brightness to the first brightness. In this embodiment, the brightness compensation signal LCS can be received by the inverter 216. The inverter 216 can have a brightness control circuit (not shown), and therefore, when the inverter 216 is receiving brightness compensation After the compensation signal LCS, the backlight unit 218 can be supplied with an appropriate duty cycle according to the brightness compensation signal LCS. Of course, the inverter 216 is not limited to brightness compensation by the brightness control circuit, which can configure other circuits or devices to achieve the effect of brightness compensation.

In summary, the display of the present invention, and the driving device and the driving method thereof have at least the following advantages: the driving device has a brightness compensation unit, and can compensate the inverter for controlling the backlight unit to work cycle, and then provide the light source for the backlight unit. Perform brightness compensation. In this way, even if the backlight unit is in a low duty cycle for a long time, the brightness of the light source is not attenuated and stable brightness can be maintained. Applying the driving device to the display and using the driving method, the display panel not only has the advantages of power saving and high contrast when displaying the dynamic picture, but also solves the brightness degradation caused by the backlight unit operating in the low duty cycle. problem.

Although the present invention has been disclosed in the above preferred 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. Therefore, the scope of the invention is defined by the scope of the appended claims.

200‧‧‧ display

210‧‧‧ drive

212‧‧‧Image Signal Processing Unit

214‧‧‧Brightness compensation unit

214a‧‧‧Work cycle statistics unit

214b‧‧‧Checklist unit

216‧‧‧Inverter

218‧‧‧Backlight unit

220‧‧‧ display panel

B ₂₀ ', B ₁₀₀ ', B ₂₀ , B ₁₀₀ ‧ ‧ brightness

Duty‧‧‧ work cycle data

IS‧‧‧ video signal

LCS‧‧‧Brightness compensation signal

S402, S404, S406‧‧‧ steps

FIG. 1A is a schematic diagram of a duty cycle-time curve of a conventional backlight unit using dynamic backlight technology.

FIG. 1B is a schematic diagram of a brightness-time curve of a conventional backlight unit using dynamic backlight technology.

2A is a block diagram of a display in accordance with a preferred embodiment of the present invention.

2B is a block diagram of the driving device of FIG. 2A.

3A is a schematic diagram showing a duty cycle-time curve of a driving device according to a preferred embodiment of the present invention.

FIG. 3B is a schematic diagram of a brightness-time curve of a driving device according to a preferred embodiment of the present invention.

4 is a flow chart of a driving method according to a preferred embodiment of the present invention.

210‧‧‧ drive

212‧‧‧Image Signal Processing Unit

214‧‧‧Brightness compensation unit

214a‧‧‧Work cycle statistics unit

214b‧‧‧Checklist unit

216‧‧‧Inverter

218‧‧‧Backlight unit

220‧‧‧ display panel

Duty‧‧‧ work cycle data

IS‧‧‧ video signal

LCS‧‧‧Brightness compensation signal

Claims (15)

A driving device for driving a backlight unit to emit a light source, the driving device comprising: an image signal processing unit, receiving an image signal and outputting a duty cycle data according to the image signal; and a brightness compensation unit coupled to the The image signal processing unit receives and counts the work cycle data. When the work cycle data is in a set working cycle for a period of time, the light source changes from a first brightness to a second brightness. The unit outputs a brightness compensation signal, the brightness compensation unit includes a work cycle statistics unit and a lookup table unit, and the work cycle statistics unit receives the work cycle data and counts the number or time of occurrence of the set work cycle in the work cycle data. When the number or time of the set working period exceeds a predetermined value, the lookup unit uses the lookup table of the lookup unit to find the brightness compensation signal, wherein the lookup table includes the time when the set working period continues to occur. The relationship with the brightness compensation signal; and an inverter coupled Between the luminance compensation unit and the backlight unit, the inverter receives the luminance signal and the compensation signal based on the luminance compensation to compensate the brightness of the backlight unit, so that the second brightness change for the first luminance. The driving device of claim 1, wherein the image signal processing unit counts the image signal to obtain a gray scale distribution data, and outputs the work cycle data according to the gray scale distribution data. The driving device according to claim 1, wherein the lighting device The degree compensation signal is a duty cycle compensation signal. The driving device of claim 1, wherein the working period data is in the set working period for a period of 5 minutes to 10 minutes. The driving device according to claim 1, wherein the setting working period is between 10% and 30%. A display device includes: a driving device for driving a backlight unit to emit a light source, the driving device comprising: an image signal processing unit, receiving an image signal and outputting a working period data according to the image signal; The unit is coupled to the image signal processing unit, and the brightness compensation unit receives and counts the work cycle data. When the work cycle data is in a set working cycle for a period of time, the light source changes from a first brightness to a second brightness. At this time, the brightness compensation unit outputs a brightness compensation signal, the brightness compensation unit includes a work cycle statistics unit and a lookup table unit, and the work cycle statistics unit receives the work cycle data and counts the set work cycle in the work cycle data. The number or time of occurrence, when the number or time of occurrence of the set working period exceeds a predetermined value, the lookup unit uses the lookup table of the lookup unit to find the brightness compensation signal, wherein the lookup table includes the setting work The relationship between the time during which the period continues to appear and the brightness compensation signal; And An inverter is coupled between the brightness compensation unit and the backlight unit, and the inverter receives the brightness compensation signal and performs brightness compensation on the backlight unit according to the brightness compensation signal, so that the second brightness is changed to The first brightness; and a display panel electrically connected to the driving device. The display device of claim 6, wherein the image signal processing unit counts the image signal to obtain a gray scale distribution data, and outputs the work cycle data according to the gray scale distribution data. The display of claim 6, wherein the brightness compensation signal is a duty cycle compensation signal. The display of claim 6, wherein the period of time during which the work cycle data is in the set duty cycle is 5 minutes to 10 minutes. The display device of claim 6, wherein the setting work period is between 10% and 30%. A driving method for driving a backlight unit to emit a light source, the driving method comprising: receiving an image signal and outputting a work cycle data according to the image signal; receiving and counting the work cycle data, when the work cycle data is in a Setting a duty cycle for a period of time, the light source changes from a first brightness to a second brightness, and outputs a brightness compensation signal; and using a brightness compensation unit to receive and count the duty cycle data and output the brightness compensation signal, wherein The brightness compensation unit includes a working week And a check-up unit, the work cycle statistics unit receives the work cycle data and counts the number or time of occurrence of the set work cycle in the work cycle data, when the set work cycle occurs for a number of times or times exceeding a predetermined period a value, the lookup unit uses the lookup table of the lookup unit to find the brightness compensation signal, wherein the lookup table includes a relationship between the time when the set duty cycle continues to appear and the brightness compensation signal; and receiving the brightness compensation And performing brightness compensation on the backlight unit according to the brightness compensation signal to change the second brightness to the first brightness. The driving method of claim 11, further comprising: using an image signal processing unit, counting the image signal to obtain a gray scale distribution data, and outputting the work cycle data according to the gray scale distribution data. The driving method of claim 11, wherein the brightness compensation signal is a duty cycle compensation signal. The driving method of claim 11, wherein the working period data is in the set working period for a period of 5 minutes to 10 minutes. The driving method described in claim 11, wherein the setting working period is between 10% and 30%.