LED electronic sign board capable of power-saving per pixel line

The invention relates to an LED electronic sign board capable of power-saving per pixel line, comprising: an LED display panel; a panel driver; a switching mode power supply that receives AC power, generates driving power required to operate the LED display panel and the panel driver and supplies power to the LED display panel and the panel driver; a black line extractor that analyzes an image signal which will be displayed on the LED display panel and extracts pixel lines which becomes black per LED module; and a main controller that controls the panel driver to display an image on the LED display panel according to the image signal, and that controls a switching signal for the operation of the switching mode power supply to shut off driving power that is supplied to the pixel lines extracted by the black line extractor from the switching mode power supply.

TECHNICAL FIELD

The invention relates to an LED electronic sign board capable of power-saving per pixel line, and in particular an LED electronic sign board capable of shutting off driving power per pixel line of a plurality of LED modules constituting an LED display panel by controlling a switching signal of a switching mode power supply (SMPS) which supplies driving power to an LED display panel and a panel driver, thereby minimizing energy consumption.

BACKGROUND

LED stands for a semi-conductor element, i.e., a Light Emitting Diode and is being used for an electronic screen for various electronic devices which displays various colors such as red, green, blue, yellow, etc.

An LED electronic sign board has a plurality of LEDs in a matrix which constitute pixels to display various images. Various LED electronic sign boards are installed inside or outside of the building for the advertisement or the delivery of information.

Recently, LED electronic sign board is widely being used for the display of moving image such as TV commercial as well as the display of simple texts or still images and becomes bigger, which causes the increase of electric power consumed on the LED electronic sign board. Considering that power saving technology is becoming increasingly common in the industry, it is required to reduce electric power consumed on the LED electronic sign board.

DISCLOSURE

Technical Problem

To reduce power consumed by LED electronic sign board, it may be suggested to shut off a commercial AC power source for the LED electronic sign board itself when the LED electronic sign board is not in use. In reality, however, the shut-off is applied only when the LED electronic sign board is not in use for a long time because the shut-off may cause damage to a circuit. Therefore, it is barely possible to shut off a commercial AC power source in real time whenever necessary.

To solve the above problem, the invention provides an LED electronic sign board capable of power-saving per pixel line to shut off driving power per pixel line of a plurality of LED modules constituting an LED display panel by controlling a switching signal of a switching mode power supply (SMPS) which supplies driving power to an LED display panel and a panel driver, thereby minimizing energy consumption.

Technical Solution

The purpose of the invention is achieved by an LED electronic sign board capable of power-saving per pixel line, comprising: an LED display panel comprising a plurality of LED modules arranged in a matrix to form a screen, wherein each LED module includes a predetermined number of LEDs; a panel driver comprising a plurality of module drivers to drive the LED modules, respectively, wherein each module driver corresponds to each LED module to display an image on each LED module; a switching mode power supply which receives AC power, generates driving power required to operate the LED display panel and the panel driver and supplies power to the LED display panel and the panel driver; a black line extractor which analyses an image signal which will be displayed on the LED display panel and extracts pixel lines which becomes black per LED module; and a main controller which controls the panel driver to display an image on the LED display panel according to the image signal, and which controls a switching signal for the operation of the switching mode power supply to shut off driving power which is supplied to the pixel lines extracted by the black line extractor from the switching mode power supply.

Further, the switching mode power supply comprises a plurality of individual SMPS units which supplies driving power to at least one of the plurality of LED modules and at least one of the plurality of module drivers, respectively; each individual SMPS unit comprises a plurality of line power supply units which supply driving power to each pixel line of the LED module per pixel line; each line power supply unit comprises an input rectifier circuit which rectifies AC power, a switching circuit which switches the power rectified by the input rectifier circuit and generates a square wave, a output rectifier circuit which receives and rectifies the square wave from the switching circuit and generates driving power, and a switching controller which controls switching operation of the switching circuit; and the main controller controls the switching controller to stop the output of the square wave of the switching circuit by controlling a switching signal of the switching controller, whereby driving power which is supplied to the pixel line extracted by the black line extractor being shut off.

Advantageous Effects

According the invention, an LED electronic sign board capable of power-saving per pixel line is provided to shut off driving power per pixel line of a plurality of LED modules constituting an LED display panel by controlling a switching signal of a switching mode power supply (SMPS) which supplies driving power to an LED display panel and a panel driver, thereby minimizing energy consumption.

MODE FOR INVENTION

Hereinafter, the invention will be described in more detail, referring to the attached drawings.

FIG. 1shows a perspective view of a power-saving LED electronic sign board100andFIG. 2represents a control block diagram of the LED electronic sign board100. As shown inFIGS. 1 and 2, the LED electronic sign board100comprises an LED display panel10, a panel driver20, a video converter50, a switching mode power supply30, a black line extractor70and a main controller40.

The video converter50converts an image signal which is received from the outside into a digital-formatted image signal capable of being processed by the panel driver20. In this regard, the video converter50comprises an A/D converter which converts an analog image signal into a digital-formatted signal, and a DVI decoder to process a digital-formatted image signal. Also, the video converter50comprises a video correction unit which corrects a digital image signal by means of a preset image correction algorithm. Alternatively, the video converter may be implemented in various forms which are already known in the field of the art.

The LED display panel10comprises a plurality of LEDs to form a screen and displays an image on a screen by the operation of a panel driver20. The display panel10is configured such that one pixel includes at least two LEDs. In one example, the display panel is configured such that a red LED, a green LED and a blue LED constitute one pixel (full-color type), or such that a red LED and a green LED constitute one pixel (3-color type).

The LED display panel10forms a screen in such a manner that a predetermined number of LEDs are arranged to constitute LED module10a,10band10cand a plurality of LED modules are arranged in a matrix form. In one example, one LED module10a,10band10cis made of 16×16 pixels and a plurality of LED modules10a,10band10care arranged in a matrix form to form a full screen of LED display panel10.

The panel driver20drives the LED display panel10to display an image on the LED display panel10by using digital image signals from the video converter50. As shown inFIG. 3, the panel driver20according to the invention comprises a plurality of module drivers20a,20band20cwhich are configured to correspond to each LED module10a,10band10cand which drive LED modules10a,10band10c, respectively to display an image on each LED module10a,10band10c. The main controller40controls LED modules10a,10band10c, respectively according to digital image signals from video converter50such that images on each LED module10a,10band10care combined for the display of a full image.

The switching mode power supply30receives a commercial AC power, generates driving power required to drive the LED display panel10and the LED modules10a,10band10cand then supplies the power to the display panel10and the panel driver20. The switching mode power supply30provides the LED display panel10and the panel driver20with DC power having a preset voltage level which is switched according to PWM (pulse width modulation) signals.

As shown inFIG. 3, the switching mode power supply30comprises a plurality of individual SMPS units30a,30band30c. Each individual SMPS unit30a,30band30cis provided to supply driving power to each LED module10a,10band10cand each module driver20a,20band20cwhich drives an associated LED module10a,10band10c. Therefore, when the output from driving power source of one individual SMPS unit30a,30band30cis stopped, one LED module10a,10band10cand one module driver20a,20band20cwhich drives the LED module are disconnected with the driving power source.

The black line extractor70extracts a pixel line which will be displayed black per LED module20a,20band20cby analyzing an image signal to be sent to the LED display panel10.FIG. 2is an example showing that pixel lines which will be displayed black are extracted from an image signal transferred from the video converter50to the panel driver20. Alternatively, the pixel line which will be displayed black may be extracted during a signal processing in the video converter50or during a signal processing in the panel driver20.

The main controller40controls the panel driver20such that an image is displayed on the LED display panel10according to the image signal. Also, the main controller40controls a switching signal of the switching mode power supply30to shut off driving power transferred from the switching mode power supply to the pixel line extracted by the black line extractor70.

Referring toFIGS. 4 to 6, each individual SMPS unit30a,30band30ccomprises a plurality of line power supply units30a_1,30a_2and30a_3which supply driving power to pixel lines11_1,11_2and11_N, respectively and each line power supply unit is configured to correspond to each pixel line of the LED module10a,10band10c.

The main controller40controls a switching signal of the line power supply unit30a_1,30a_2and30a_3which supplies driving power to corresponding pixel line11_1,11_2and11_N to shut off driving power which is supplied to pixel lines11_1,11_2and11_N corresponding to pixel lines11_1,11_2and11_N extracted by the black line extractor70.

Referring toFIG. 5, in case that there is a black area (BA) which is displayed black on a screen, if one LED module10a,10band10cis within the black area (BA), the main controller40controls switching signals of the line power supply units30a_1,30a_2and30a_3of the corresponding individual SMPS unit30a,30b,30csuch that driving power supplied to the entire pixel lines11_1,11_2and11_N of the corresponding LED module10a,10band10cis shut off. Specifically, switching signals are controlled to shut off driving power supplied from all line power supply units30a_1,30a_2and30a_3.

As shown in an A area ofFIG. 5, in case that only some pixel lines (see the black pixel lines inFIG. 6) of the pixel lines11_1,11_2and11_N of one LED module10a,10band10care displayed black, the main controller40controls switching signals of the corresponding line power supply units30a_1,30a_2and30a_3such that driving power supplied to the corresponding pixel lines11_1,11_2and11_N is shut off.

FIG. 7represents an example of a line power supply unit30a_1,30a_2and30a_3according to the invention. As shown inFIG. 7, the line power supply unit30a_1,30a_2and30a_3according to the invention comprises a filter circuit31a, an input rectifier circuit32a, a switching circuit33a, an output rectifier circuit34a, a DC/DC converter35aand a switching controller36a.

The input rectifier circuit32arectifies AC power which is input thereto. The input rectifier circuit32acomprises a full-wave bridge diode and a condenser, and rectifies AC power, e.g., 220V AC power and generates 300V DC voltage having a ripple.

The switching circuit33agenerates a square wave by switching DC power which is generated by the rectification of the input rectifier circuit32a. The switching circuit33aconsists of a switching element such as Field Effect Transistor (FET), and generates a square wave by switching DC power which is generated from the input rectifier circuit32a.

The output rectifier circuit34agenerates DC voltage by rectifying a square wave from the switching circuit33a. Then, DC/DC converter35acontrols a voltage level of DC voltage from the output rectifier circuit34aand then generates driving power having a voltage level to drive the LED module10a,10band10cand driving power having a voltage level to drive the module driver20a,20band20c.

The switching controller36acontrols a switching operation of the switching circuit33asuch that the switching circuit33agenerates a square wave. The switching controller36acontrols the switching circuit33aby a PWM control which controls the switching circuit33aby means of PWM signals.

The main controller40sends a control signal (PWM_C_S) to the switching controller36aof the line power supply unit30a_1,30a_2and30a_3such that the switching controller36acontrols a switching operation of the switching circuit33a. The switching controller36acontrols a switching signal, i.e., a PWM signal which is sent to the switching circuit33aso as to stop the output of a square wave of the switching circuit33a.

FIG. 8represents an example of a PWM signal which is sent from the switching controller36ato the switching circuit33aand describes that the switching controller36agenerates a PWM signal in the form of a pulse wave for the generation of driving power, and when a control signal (PWM_C_S) is received from the main controller40, then converts the PWM signal into LOW state so as to stop off the output of a square wave.

As described above, the main controller40controls a switching signal of the switching mode power supply30such that driving power supplied to a plurality of pixel lines11_1,11_2,11_N of each LED module10a,10band10cin the LED display panel10is made ON/OFF selectively. Therefore, the ON/OFF switching is made possible with no damage to the circuit.

Therefore, by shutting off the black area (BA) which displays black image on the LED electronic sign board100according to the invention per pixel line11_1,11_2,11_N, it is possible to shut off wasting power stably.

Further, a switching signal, i.e., a PWM signal, itself is changed into LOW state to stop the output of the driving power itself, thereby eliminating power loss which a black-process causes in a state of driving power being connected like the conventional devices.

It is intended that the foregoing description has described only a few of the many possible implementations of the present invention, and that variations or modifications of the embodiments apparent to those skilled in the art are embraced within the scope and spirit of the invention.