WO2017193494A1

WO2017193494A1 - Low-power-consumption liquid crystal display device backlight loop and control method therefor

Info

Publication number: WO2017193494A1
Application number: PCT/CN2016/094784
Authority: WO
Inventors: 张明辉
Original assignee: 福建联迪商用设备有限公司
Priority date: 2016-05-10
Filing date: 2016-08-12
Publication date: 2017-11-16
Also published as: CN105810155A

Abstract

A low-power-consumption liquid crystal display device backlight loop and a control method therefor. A backlight loop comprises an LED lamp control module (100), an LED lamp driving module (200), and an LED lamp backlight module (300), the LED lamp control module (100) controlling, according to the luminance required to be reached by a liquid crystal device, the LED lamp backlight module (300) by means of the LED lamp driving module (200); the LED lamp driving module (200) being used for driving the LED lamp backlight module (300); and the LED lamp backlight module (300) being used for providing the liquid crystal display device with a required light source. The control method enables an LED lamp having a liquid crystal display device backlight to operate on a current having a high light-emitting efficiency, thereby reducing the heat loss of the liquid crystal device, improving the light-emitting efficiency of the LED lamp and the energy efficiency ratio of the liquid crystal display device.

Description

Low-power liquid crystal display device backlight circuit and control method thereof

Technical field

The invention relates to a low power consumption liquid crystal display device backlight circuit and a control method thereof.

Background technique

Traditionally, with the concept of energy saving and environmental protection, people gradually choose products with lower power consumption when purchasing electronic products. Especially for battery-powered products, having lower power consumption can greatly improve the product usage time. At the same time, with the continuous improvement of industry energy consumption standards and users' increasingly demanding power consumption requirements, enterprises are also forced to increase investment and reduce the energy consumption level of products to enhance product competitiveness.

Among display devices, liquid crystal display devices are widely used because of their good display performance and low power consumption.

The liquid crystal itself does not emit light, but is illuminated by the backlight of the liquid crystal. In order to further reduce the power consumption of the liquid crystal display device, the backlight of the liquid crystal display device has been gradually replaced from the conventional fluorescent tube into the existing LED tube, and the LED lamp The tube has the advantages of high luminous efficiency and high energy conversion efficiency compared with the fluorescent tube.

LED lights are also called light-emitting diodes. They have many characteristics of diodes. Under the condition that the LED lights are fully turned on, the smaller the current flowing through the LED lamps, the higher the luminous efficiency, and the current dimming mode of liquid crystal display devices is By adjusting the current of the LED backlight, the higher the brightness, the larger the current required. As the current increases, the LED luminous efficiency will gradually decrease.

However, with the gradual maturity of LED lighting technology, the luminous efficiency of LED lamps has been difficult to improve, and even stopped, which has increased the difficulty for related companies to reduce the power consumption of liquid crystal display devices.

Figure 1 is a conversion diagram of the input power energy of the LED lamp. The power of the input LED lamp is 68% as heat loss, and only about 32% of the power is converted into visible light.

The brightness adjustment of the current liquid crystal display device is achieved by adjusting the current of the backlight LED lamp. The number of LED lamps in the backlight of the liquid crystal display device is fixed, and the brightness of the liquid crystal display device needs to be increased, and the current through the LED lamp must be continuously increased. In reality, however, the LED lamp luminous efficiency η and the energy conversion efficiency ηe are gradually reduced as the current increases, as shown in FIG.

The reduction of luminous efficiency means that more electric energy is converted into unnecessary thermal energy, which is wasted. The direct consequence is that the power consumption of the liquid crystal display device is getting larger and larger, and the energy efficiency is getting lower and lower.

At the same time, the more thermal energy emitted by the LED lamp, the higher the surface temperature of the liquid crystal display device, with As the temperature increases, the reliability of the liquid crystal display device also gradually decreases.

The invention changes the control mode of the LED backlight, changes the brightness from the current current of adjusting a fixed number of LED lamps, and changes the number of the LED lights to control the brightness. If the brightness required by the user is higher, the more the number of LED lights that are lit, the same reason, if the brightness needs to be reduced, the number of LED lights that are illuminated is gradually reduced. That is, on the basis of ensuring high luminous efficiency of the LED lamp, the method of adjusting the brightness of the liquid crystal backlight is changed from the current method of adjusting the current amount of the fixed number of LED lamps to controlling the amount of illumination of the backlight LED lamp.

Summary of the invention

An object of the present invention is to provide a low-power liquid crystal display device backlight circuit and a control method thereof, which can solve the above-mentioned deficiencies, and can reduce all LED lights of a liquid crystal backlight to operate at a current with high luminous efficiency, thereby reducing The heat loss of the liquid crystal device improves the luminous efficiency of the LED lamp and the energy efficiency ratio of the liquid crystal display device.

In order to achieve the above object, the technical solution of the present invention is: a low-power liquid crystal display device backlight circuit, including an LED lamp control module, an LED lamp driving module, and an LED lamp backlight module.

The LED lamp control module controls the LED lamp backlight module through the LED lamp driving module according to the brightness that the liquid crystal display device needs to achieve;

The LED lamp driving module is configured to drive an LED lamp backlight module;

The LED light backlight module is used to supply a light source required for a liquid crystal display device.

In an embodiment of the invention, the LED light control module includes a CPU and a Flash connected thereto.

In an embodiment of the invention, the LED lamp driving module includes an LED driving chip and a power module, wherein the LED driving chip is used to drive an LED light string of the LED light backlight module to emit light, and the power module is used to provide a driving LED light. String the required power.

In an embodiment of the invention, the LED backlight module includes at least one LED light string for providing a light source required for the liquid crystal display device.

In an embodiment of the invention, the LED light string includes at least one LED light, and the LED lights of each LED light string are numbered, and each LED light is separately controlled.

The present invention also provides a control method for a backlight circuit of a liquid crystal display device based on the low power consumption described above, comprising the following steps,

S1: Turn on all the LED lights, that is, when the number of LED lights is turned on, the maximum number of liquid crystal display devices is determined. High brightness Ymax;

S2: sorting the LED lights, and dividing the gear position M according to the brightness Y of the liquid crystal display device when the number of the LED lights is n;

S3: According to the brightness required by the liquid crystal display device, the LED lamp control module can control the number of LED lamps to be turned on by the LED lamp driving module according to the correspondence relationship between the gear position M and the brightness Y of the liquid crystal display device.

In an embodiment of the invention, the step S1 and S2 further includes a step of determining the minimum opening number nmin of the LED lamp, and if the brightness Y of the liquid crystal display device reaches the minimum opening number nmin of the LED lamp, To further reduce the brightness, the brightness adjustment is performed by adjusting the current of the LED lamp at this time.

In an embodiment of the present invention, in the step S1, it is necessary to ensure that all the LED lamps are operated at a higher luminous efficiency η value, that is, according to the LED lamp luminous efficiency curve, ensure that all the LED lamps are operated at the luminous efficiency η at a certain illumination. The efficiency threshold η _is above a _threshold , wherein the η _{threshold is} 100 lm/W.

In an embodiment of the invention, the LED lights arranged in a matrix are sorted, that is, the LED lights arranged in a matrix are sorted from left to right and top to bottom.

In an embodiment of the present invention, the dividing of the gear position M is performed according to the brightness Y of the liquid crystal display device when the number of the LED lamps is turned on, that is, according to the corresponding number of the opening LED lamps n and the brightness Y of the liquid crystal display device In the curve, the division of the gear position M is performed such that the gear position M is proportional to the brightness Y of the liquid crystal display device.

Compared with the prior art, the present invention has the following beneficial effects: the invention can make all the LED lights of the liquid crystal backlight can work on the current with higher luminous efficiency, thereby reducing the heat loss of the liquid crystal device and improving the LED lamp. Luminous efficiency and energy efficiency ratio of liquid crystal display devices.

DRAWINGS

Figure 1 is a conversion diagram of input lamp power energy of an LED lamp.

Figure 2 is a graph showing the luminous efficiency of an LED lamp.

3 is a flow chart of a backlight circuit control of a low power consumption liquid crystal display device of the present invention.

4 is a schematic block diagram of a backlight circuit of a low power consumption liquid crystal display device according to the present invention.

Fig. 5 is a graph showing the correspondence between the number of open LED lamps and the brightness of the liquid crystal display device.

FIG. 6 is a schematic diagram showing the correspondence between the number of LED lamps and the brightness position of the liquid crystal display device according to an embodiment of the invention.

Fig. 7 is a schematic view showing the arrangement of a direct type LED lamp in a liquid crystal display device.

FIG. 8 is a schematic view showing the arrangement structure of the side light type LED lamps in the liquid crystal display device.

FIG. 9 is a schematic view showing the arrangement of LED lamps in the liquid crystal display device of the present invention.

detailed description

The technical solution of the present invention will be specifically described below with reference to the accompanying drawings.

A low-power liquid crystal display device backlight circuit of the invention comprises an LED lamp control module, an LED lamp driving module and an LED lamp backlight module,

The LED light control module controls the LED light backlight module through the LED light driving module according to the brightness that the liquid crystal display device needs to achieve; the LED light control module includes a CPU and a Flash connected thereto;

The LED lamp driving module is configured to drive an LED lamp backlight module; the LED lamp driving module includes an LED driving chip and a power module, and the LED driving chip is used to drive an LED lamp string of the LED lamp backlight module to emit light, and the power module Used to provide the power required to drive the LED string;

The LED light backlight module is configured to provide a light source required for a liquid crystal display device; the LED backlight module includes at least one LED light string for providing a light source required for the liquid crystal display device; the LED light string includes at least one LED light And the LED lights of each LED light string are numbered, and each LED light is separately controlled.

S1: Turn on all the LED lights, that is, when the number of LED lights nmax is turned on, determine the highest brightness Ymax of the liquid crystal display device;

S2: sorting the LED lights (the LED lights are arranged in a matrix or the side light arrangement), and dividing the gear position M according to the brightness Y of the liquid crystal display device when the number of the LED lights is n; the matrix is arranged The LED lights are sorted by number, that is, the LED lights arranged in a matrix are sorted from left to right and top to bottom. The dividing of the gear position M according to the brightness Y of the liquid crystal display device when the number of the open LED lamps is n, specifically according to the corresponding curve of the number of open LED lamps n and the brightness Y of the liquid crystal display device (as shown in FIG. 5) The division of the gear position M is performed such that the gear position M is proportional to the brightness Y of the liquid crystal display device.

The step S1 and S2 further includes a step of determining the minimum opening number nmin of the LED lamp. If the brightness Y of the liquid crystal display device reaches the minimum opening number nmin of the LED lamp, further reducing the brightness is required, and then adjusting At this time, the current of the LED lamp is used to adjust the brightness.

In the step S1, it is necessary to ensure that all the LED lamps are operated at a higher luminous efficiency η value, that is, according to the LED lamp luminous efficiency curve (as shown in FIG. 2), to ensure that all the LED lamps are operated at the luminous efficiency η at a luminous efficiency. The threshold η _{threshold is} above, wherein the η _{threshold is} 100 lm/W.

The following is a specific implementation process of the present invention.

As shown in FIG. 4, the low-power liquid crystal display device backlight circuit of the present invention includes an LED lamp control module 100, an LED lamp driving module 200, and an LED lamp backlight module 300.

The LED light control module 100 includes a CPU 110 and a flash 120;

The LED lamp driving module 200 includes an LED driving chip 210 and a power module 220;

The LED backlight module 300 includes an LED light string 1 310, an LED light string 2 320, and an LED light string 3 330.

The CPU 110 is used to process instructions, perform operations, control time, process data, and the like.

The Flash 120 is used to store related control software.

The LED driving chip 210 is used to drive the LED lamp to emit light.

The power module 220 is used to provide power required to drive the LED lights.

The LED string is turned on after being driven to provide a light source required for the liquid crystal device.

As shown in FIG. 3 , the present invention also provides a control method for a backlight circuit of a low power consumption liquid crystal display device, which can make all LED lights of the liquid crystal backlight can work on a current with high luminous efficiency, thereby reducing liquid crystal. The heat loss of the device improves the luminous efficiency of the LED lamp and the energy efficiency ratio of the liquid crystal display device, including the following steps,

S1, determining the highest brightness that the liquid crystal device needs to achieve, and the highest brightness is the maximum brightness Ymax that the liquid crystal device can achieve at the beginning of design, as defined by the design specification;

S2. Determine the number of LED lamps nmax required to reach the maximum design brightness Ymax while ensuring that all LED lamps are operated at a current with high luminous efficiency.

S3. The display device generally has a default brightness Ydef. This default brightness is generally not set directly on the maximum brightness Ymax of the liquid crystal device, but will take a value from 0 to Ymax. By confirmation, to reach The number of LEDs to be turned on by default brightness Ydef is ndef, and satisfies ndef<nmax.

S4. If it is necessary to increase the brightness, increase the number of open LED lights until the maximum brightness Ymax is reached. At this time, the number of open LED lights is nmax, that is, all the LED lights are turned on; if it is required to reduce the brightness, the open LED lights are reduced. Number, until the minimum brightness is reached, the number of LED lights turned on at this time is 0, that is, the following relationship is satisfied:

The number of LED lamps = ndef ± x (x = 0, 1, 2, 3...), the maximum number of LEDs is equal to nmax, and the minimum value is equal to zero.

As shown in Figures 7 and 8, there are two structures for LED backlight: direct type and side light type.

As shown in Fig. 7, the direct type: the direct type backlight has a simple process, and the LED lamp has a uniform liquid crystal panel bottom, but the direct type liquid crystal panel is thick and is currently used less.

Figure 8 is a side-light type: LED lights are placed at the edge of the visible area of the panel, typically the upper and lower edges. After the LED light is illuminated, the light is evenly transmitted by the reflector and the diffuser to the entire panel, which is called the side light type, which can make the liquid crystal panel more light and thin. For a liquid crystal panel with a size smaller than 24 inches, the LED light generally only needs to be placed. At the lower edge, the LCD panel is larger than 24 inches, and the general LED lights are distributed on the upper and lower edges.

The technical solution of the present invention will be described below by way of specific embodiments.

Embodiment 1:

This embodiment designs an edge-lit liquid crystal device having a maximum luminance of 200 cd/m 2 and a size of 3.5 inches.

As shown in Figure 9, the LED lights are all placed on the lower edge of the liquid crystal device.

First, the brightness of the liquid crystal device was measured, and it was confirmed that when the maximum design brightness of 200 cd/m2 was reached, the number of LED lamps to be turned on was 15, and 15 LED lamps were all operated at a current with high luminous efficiency.

The brightness of the liquid crystal device needs to be adjustable, and the position of the brightness adjustment is preset. This embodiment is set to have 15 positions for the brightness to be adjusted.

Referring to FIG. 6, the vertical axis is the corresponding brightness gear position value M, and the horizontal axis is the corresponding number of LED lights opened n and the serial number corresponding to the opened LED lamp.

When the brightness gear value is 1, one LED light is turned on, and the LED light of serial number 8 is turned on;

When the brightness gear position value is 2, open 2 LED lights, compared with gear position 1, increase the opening LED lamp with serial number 4;

When the brightness gear value is 3, open 3 LEDs, etc.; compared with gear 2, increase the opening LED lamp with serial number 12;

When the brightness unit value is 4, 4 LED lights are turned on; compared with the gear position 3, the LED lamp with the serial number 2 is added;

When the brightness unit value is 5, 5 LED lights are turned on; compared with the gear position 4, the LED lamp with the serial number 10 is turned on;

When the unit value of the brightness is 6, the 6 LED lights are turned on; compared with the gear position 5, the LED lamp with the serial number 6 is turned on;

When the unit value of the brightness is 7, the 7 LED lights are turned on; compared with the gear position 6, the LED lamp with the serial number 14 is turned on;

When the unit value of the brightness is 8, the 8 LED lights are turned on; compared with the gear position 7, the LED lamp with the serial number 1 is added;

When the unit value of the brightness is 9, the 9 LED lights are turned on; compared with the gear position 8, the LED lamp with the serial number 9 is turned on;

When the brightness unit value is 10, 10 LED lights are turned on; compared with the gear position 9, the LED lamp with the serial number 5 is turned on;

When the unit value of the brightness is 11, the 11 LED lights are turned on; compared with the gear position 10, the LED lamp with the serial number 13 is turned on;

When the brightness unit value is 12, 12 LED lights are turned on; compared with the gear position 11, the LED lamp with the serial number of 11 is turned on;

When the unit value of the brightness is 13, the 13 LED lights are turned on; compared with the gear position 12, the LED lamp with the serial number 3 is turned on;

When the brightness unit value is 14, the 14 LED lights are turned on; compared with the gear position 13, the LED lamp with the serial number 15 is turned on;

When the brightness gear value is 15, turn on 15 LED lights, that is, all the LED lights are turned on.

Further, in the process of gradually turning on or off the LED lamp, the serial number of the switch LED lamp is not fixed, and may vary according to the design or material selection of the liquid crystal device.

Further, in fact, the ratio of the display brightness of the liquid crystal device to the number of open LED lamps is not a fixed value, but a curve similar to that of FIG. 5, the horizontal axis is the number of open LED lamps, and the vertical axis is the display brightness of the liquid crystal device. .

If the gear position value of the brightness of the product is required to be proportional to or close to the actual brightness, The current brightness needs to be turned on by measuring the brightness of the liquid crystal device. In this way, the ratio of the actual brightness to the gear position can be made linear.

Further, the brightness can be adjusted, the gear position is not fixed, and can be designed according to actual needs, generally no more than 100 gear positions.

Further, considering the brightness uniformity B/U (Brightness uniformity), if there are too few LED lights to be turned on, the difference in brightness of different points on the screen may be relatively large. At this time, a minimum number of LED lights can be set as needed. Nmin, that is, in the process of reducing the number of open LED lights, when the number of open LED lights is equal to nmin, the LED lights will not be turned off, but the brightness is adjusted by adjusting the current of the remaining nmin LED lights, so that It avoids the problem of large difference in brightness between different points on the screen.

Further, the default brightness value of the display device is generally set between 50% and 90% of the maximum brightness of the display device.

Further, LED lamps of different specifications have different currents with higher working efficiency, and the required LED lamps are selected according to actual needs during design.

The above is a preferred embodiment of the present invention. Any changes made by the technical solutions of the present invention, and the functions produced by the present invention are not within the scope of the technical solutions of the present invention.

Claims

A low-power liquid crystal display device backlight circuit, comprising: an LED lamp control module, an LED lamp driving module and an LED lamp backlight module,

The LED lamp control module controls the LED lamp backlight module through the LED lamp driving module according to the brightness that the liquid crystal display device needs to achieve;

The LED lamp driving module is configured to drive an LED lamp backlight module;

The LED light backlight module is used to supply a light source required for a liquid crystal display device.
The backlight circuit of a low power consumption liquid crystal display device according to claim 1, wherein the LED lamp control module comprises a CPU and a Flash connected thereto.
The backlight circuit of a low-power liquid crystal display device according to claim 1, wherein the LED lamp driving module comprises an LED driving chip and a power module, and the LED driving chip is used for driving the LED backlight module. The LED string is illuminated, and the power module is used to provide the power required to drive the LED string.
The backlight circuit of a low power consumption liquid crystal display device according to claim 1, wherein the LED backlight module comprises at least one LED light string for supplying a light source required for the liquid crystal display device.
The backlight circuit of a low power consumption liquid crystal display device according to claim 4, wherein the LED light string comprises at least one LED light, and the LED lights of each LED light string are numbered, and each LED light is separately control.
A method for controlling a backlight circuit of a low power consumption liquid crystal display device according to claim 5, comprising the steps of:

S1: Turn on all the LED lights, that is, when the number of LED lights nmax is turned on, determine the highest brightness Ymax of the liquid crystal display device;

S2: sorting the LED lights, and dividing the gear position M according to the brightness Y of the liquid crystal display device when the number of the LED lights is n;

S3: According to the brightness required by the liquid crystal display device, the LED lamp control module can control the number of LED lamps to be turned on by the LED lamp driving module according to the correspondence relationship between the gear position M and the brightness Y of the liquid crystal display device.
A method for controlling a backlight circuit of a low power consumption liquid crystal display device according to claim 6, characterized in that The step S1 and S2 further includes a step of determining the minimum opening number nmin of the LED lamp. If the brightness Y of the liquid crystal display device reaches the minimum opening number nmin of the LED lamp, further reducing the brightness is required. The brightness adjustment is performed by adjusting the current of the LED lamp at this time.
The method for controlling a backlight circuit of a low-power liquid crystal display device according to claim 6, wherein in the step S1, it is necessary to ensure that all the LED lamps operate at a higher value of the luminous efficiency η, that is, according to the luminous efficiency curve of the LED lamp. ensure that all LED lamps are working luminous efficiency [eta] is a threshold value above the threshold value [eta] luminous efficiency, wherein, the threshold [eta] takes 100lm / W.
A method for controlling a backlight circuit of a low power consumption liquid crystal display device according to claim 6, wherein said LED lamps arranged in a matrix are numbered, that is, LED lamps arranged in a matrix are arranged from left to right and top to bottom. Sort.
The method for controlling a backlight circuit of a low-power liquid crystal display device according to claim 6, wherein the dividing of the gear position M according to the brightness Y of the liquid crystal display device when the number of the open LED lamps is n is specifically opened according to The corresponding curve of the number n of LED lamps and the brightness Y of the liquid crystal display device is divided into gear positions M such that the gear position M is proportional to the brightness Y of the liquid crystal display device.