KR102637558B1 - Power saving electronic display with automatic voltage control - Google Patents

Abstract

A power-saving electronic signboard capable of automatic voltage adjustment according to the present invention includes an LED panel that displays an image source; A video source unit providing a video source; a module control unit that supplies the video source of the video source unit to the LED panel; a brightness control unit that outputs a brightness reference voltage value for controlling the brightness of the LED panel according to a predetermined brightness control signal; A D/A converter that converts a brightness reference voltage value of a digital value output from the brightness control unit into a brightness reference voltage value of an analog value; and a switching mode power supply that supplies an output voltage corresponding to the brightness reference voltage value to the LED panel.

Description

Power-saving electronic signboard with automatic voltage control {POWER SAVING ELECTRONIC DISPLAY WITH AUTOMATIC VOLTAGE CONTROL}

The present invention relates to a power-saving electric signboard capable of automatic voltage adjustment, and more specifically, to a power-saving electric signboard capable of automatic voltage control that can save power by controlling the brightness of the electric signboard by controlling the voltage applied to the LED panel according to the external environment. will be.

An electronic signboard using LED is a display device that has excellent resolution and displays color images in a variety of colors. It is installed in various forms on the exterior walls or inside of buildings for advertising or broadcasting and is used to display images or videos. The basic component of an LED signboard is a unit pixel composed of LEDs (Light Emitting Diodes) that emit red, green, and blue colors. The pixels are arranged in a horizontal and vertical matrix to form one LED panel or LED board. , several LED panels come together to form an LED sign.

Figure 1 is a configuration diagram of a standard electronic signboard according to the prior art.

A standard electronic signboard according to the prior art includes an LED panel 110 that displays an image source in units of frames, a switching mode power supply 120 that supplies power to the LED panel 110, and an image source unit 130 that provides an image source. , and a module control unit 140 that supplies the image source of the image source unit 130 to the LED panel 110 on a frame basis. However, since the switching mode power supply 120 of the standard electronic signboard according to the prior art always applies a constant voltage to the LED panel 110, the brightness of the LED panel 110 is constant even if the external illumination changes depending on the day and night, reducing power consumption. It happens the same way.

Figure 2 is a circuit diagram showing a switching mode power supply according to the prior art.

As shown in Figure 2, the switching mode power supply according to the prior art includes a power supply unit 210, a power output unit 220, a feedback voltage provider 230, a switching control unit 240, and a bias power supply unit 250. Includes.

The power supply unit 210 includes a bridge diode (BD) for rectifying the alternating current input (AC), a capacitor (Cin) for smoothing the rectified voltage, and a primary coil (L1) of the transformer whose one end is connected to the capacitor (Cin). Includes. Here, the other end of the primary coil (L1) of the transformer is connected to the terminal (f1) of the switching control unit 240. The power supply unit 210 converts an alternating current voltage (AC) into a direct current voltage (Vin) by a bridge diode (BD) and a capacitor (Cin), and the duty cycle of the main switch (Qsw) built in the switching control unit 240 ( According to duty, the desired power is supplied to the secondary side of the transistor, that is, the power output unit 220. Additionally, the terminal (VSTR) of the switching control unit 240 is connected to the node (N1) between the capacitor (Cin) and the primary coil (L1) of the transformer.

The power output unit 220 includes a diode (D1) whose anode is connected to one end of the secondary coil (L2) of the transformer, and a capacitor (C1) connected between the cathode of the diode (D1) and ground. The other end of the secondary coil (L2) is connected to ground. Here, the voltage applied across the capacitor C1 becomes the output voltage (Vout).

The feedback voltage provider 230 includes a resistor (R1) whose end is connected to the cathode of the diode (D1), a resistor (R2) connected between the other end of the resistor (R1) and ground, and a cathode at the other end of the resistor (R1). A zener diode (ZD) connected to the anode connected to the ground, a photodiode (PC1) whose anode is connected to one end of the resistor (R1) and a cathode connected to the other end of the resistor (R1), and a terminal of the switching control unit 240 ( It includes a photo transistor (PC2) connected between VFB) and ground, and a feedback capacitor (Cfb) connected in parallel with the photo transistor (PC2) and connected between the terminal (VFB) and ground. Here, the photo diode (PC1) and the photo transistor (PC2) together form a photo coupler. The output voltage (Vout) is divided by the resistors (R1, R2), and the current flowing through the photo diode (PC1) is determined in proportion to the output voltage (Vout), and the photo diode (PC1) is proportional to the current flowing through the photo diode (PC1). The current flowing through the transistor (PC2) is determined. Accordingly, the feedback voltage (Vfb) applied to both ends of the feedback capacitor (Cfb) is inversely proportional to the output voltage (Vout), and the output voltage (Vout) is regulated to a constant voltage.

The bias power supply unit 250 includes a tertiary coil (L3) of the transformer, a diode (D2) whose anode is connected to one end of the tertiary coil (L3) of the transformer, and a capacitor ( Includes C2). And, the node N2 of the capacitor C2 and the diode D2 is connected to the terminal Vcc of the switching control unit 400. Here, both ends of the capacitor C2 are charged with a bias voltage (Vcc) for operating the PWM controller 242 of the switching control unit 240. Meanwhile, the tertiary coil (L3) and diode (D2) of the transformer operate when the main switch (Qsw) starts switching to charge the capacitor (C2) with the bias voltage (Vcc).

The switching control unit 240 includes a PWM controller 242, an initial bias power supply unit 244, and a main switch (Qsw). In the main switch (Qsw), the drain is connected to the other terminal of the primary coil (L1) of the transformer through the terminal (f1), the source is connected to ground through the terminal (f2), and the gate is connected to the output terminal of the PWM controller 242. connected.

As described above, in the switching mode power supply according to the prior art, the photodiode (PC1) is turned on when the voltage on the secondary side of the transformer is always consistently higher than the Zener voltage (VZD). Accordingly, even if the external environment changes depending on day and night, the switching mode power supply supplies a constant output voltage, so the brightness of the LED panel 110 is constant and power consumption is the same.

Specifically, when using a conventional constant voltage switching mode power supply for an electronic signboard, the output voltage is fixed to 5 volts during manufacture. The power consumption of an electronic sign board is only a few milliamps of current flowing through each RGB LED, but when the current flowing through tens of thousands of LEDs is collected in a module unit, several to tens of amperes flow at the switching mode power supply output voltage of 5 volts, reaching hundreds of amperes. Watts of power are consumed.

In particular, because electronic signboards installed outdoors are implemented using tens to hundreds of modules, the power consumed by the electric signboard is enormous. However, in any case, the 5 volt output does not change to a constant voltage, so power saving due to this is impossible.

Patent registration 10-0948057 Power-saving LED display system Patent Publication No. 10-2011-0051904 Energy-saving LED power supply device Patent Registration No. 10-1481570 Green Smart Energy Saving LED Display Board Patent Registration No. 10-2364501 LED signboard standby power supply module to reduce power consumption

The purpose of the present invention is to provide a power-saving electric signboard capable of automatic voltage adjustment that can save power by adjusting the brightness of the electric signboard by controlling the voltage applied to the LED panel according to the external environment.

Another object of the present invention is to provide a power-saving electric signboard capable of automatic voltage adjustment that can save power by remotely controlling the voltage applied to the LED panel to adjust the brightness of the electric signboard.

The problems to be solved by the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

A power-saving electronic signboard capable of automatic voltage adjustment according to the present invention is installed outdoors and configured to have a plurality of switching mode power supplies apply voltage to an LED panel, comprising: the LED panel displaying an image source; A video source unit providing a video source; a module control unit that supplies the video source of the video source unit to the LED panel; a brightness control unit that outputs a brightness reference voltage value for controlling the brightness of the LED panel according to a predetermined brightness control signal; A D/A converter that converts a brightness reference voltage value of a digital value output from the brightness control unit into a brightness reference voltage value of an analog value; and a plurality of switching mode power supplies that output output voltages corresponding to the brightness reference voltage values to the LED panel, and the brightness control unit outputs different brightness reference voltage values for each RGB color.

Preferably, the predetermined brightness control signal may be a remote control signal capable of reading different brightness reference voltage values for at least one of day and night, time zone, and color image type stored in the look-up table.

Preferably, the lookup table includes a solid state disk (SSD), a universal serial bus memory (USB memory), a Secure Digital card (SD), and a mini Secure Digital card. mSD), Micro Secure Digital Card (micro SD), Secure Digital High Capacity (SDHC), Memory Stick Card, Smart Media Card (SM), Multi Media Card (Multi) It is implemented in any one of Media Card (MMC), Embedded MMC (eMMC), Compact Flash (CF), or ROM (Read Only Memory), NOR Flash Memory, NAND Flash Memory, or PRAM ( It can be implemented in any one of Phase Change Random Access Memory (RRAM), Resistive Random Access Memory (RRAM), and Magnetic Random Access Memory (MRAM).

Preferably, it may further include an illuminance sensor that outputs an illuminance sensor signal that varies depending on the brightness of the external environment during day and night.

Preferably, the brightness control unit can select and output one of a remote control signal and an illumination sensor signal according to a selection command signal included in a predetermined brightness control signal.

Preferably, the switching mode power supply includes a high-frequency PWM switching generator IC that receives a direct current voltage and generates a PWM switching signal whose pulse width is adjusted according to an optical comparison signal output from the photocoupler below; a high-frequency transformer that outputs a low voltage to the secondary side when the PWM switching signal with the adjusted pulse width is applied to the switching element; a constant voltage IC that outputs the low voltage output from the secondary side of the high-frequency transformer as a constant voltage of a predetermined level; a voltage comparator that compares the secondary output voltage of the high-frequency transformer with a brightness reference voltage of the analog value output from the D/A converter and outputs a comparison value; and a photocoupler including a photodiode that emits light according to the comparison value output from the voltage comparator and a phototransistor that outputs an optical comparison signal in response to the operation of the photodiode.

The power-saving electric sign capable of automatic voltage adjustment according to the present invention has the effect of saving power by controlling the brightness of the electric sign by controlling the voltage applied to the LED panel according to the external environment.

In particular, according to the present invention, it is possible to save power by adjusting the brightness of the electric signboard by remotely controlling the voltage applied to the LED panel. By using the reference voltage value set differently according to the external environment stored in the look-up table, the manager can There is an effect of being able to adjust the brightness of the electronic signboard without having to go directly to the site.

1 is a configuration diagram of a standard electronic signboard according to the prior art;
Figure 2 is a circuit diagram showing a switching mode power supply according to the prior art;
Figure 3 is a configuration diagram of a power-saving electronic signboard capable of automatic voltage adjustment according to an embodiment of the present invention;
Figure 4 is a circuit diagram of a switching mode power supply capable of voltage adjustment according to an embodiment of the present invention, and
Figure 5 is a circuit diagram of the main parts of a switching mode power supply capable of voltage adjustment according to an embodiment of the present invention.

Additional objects, features and advantages of the present invention may be more clearly understood from the following detailed description and accompanying drawings.

Prior to a detailed description of the present invention, it should be noted that the present invention is capable of various modifications and may have various embodiments, and the examples described below and shown in the drawings are not intended to limit the present invention to specific embodiments. No, it should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

The terms used in this specification are for describing embodiments and are not intended to limit the invention. As used herein, singular forms also include plural forms, unless specifically stated otherwise in the context. As used in the specification, 'comprises' and/or 'comprising' refers to the presence of one or more other components, steps, operations and/or elements. or does not rule out addition.

One element is said to be ‘connected to’ or ‘coupled to’ another element, when it is directly connected or coupled to another element or with another element intervening. Includes all cases. On the other hand, when one element is referred to as 'directly connected to' or 'directly coupled to' another element, it indicates that there is no intervening other element. ‘And/or’ includes each and every combination of one or more of the mentioned items.

The same reference numerals refer to the same elements throughout the specification. Accordingly, the same or similar reference signs may be described with reference to other drawings even if they are not mentioned or described in the corresponding drawings. Additionally, even if reference signs are not indicated, description may be made with reference to other drawings.

The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

In addition, terms such as "... unit", "... unit", and "... module" used in the specification refer to a unit that processes at least one function or operation, which is hardware or software or hardware and It can be implemented through a combination of software.

In addition, when describing with reference to the accompanying drawings, identical components will be assigned the same reference numerals regardless of the reference numerals, and overlapping descriptions thereof will be omitted. In describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

Figure 3 is a configuration diagram of a power-saving electronic signboard capable of automatic voltage adjustment according to an embodiment of the present invention.

A power-saving electronic signboard capable of automatic voltage adjustment according to an embodiment of the present invention includes an LED panel 310 that displays an image source in units of frames, a switching mode power supply 320 that supplies power to the LED panel 310, and an image source. An image source unit 330 that provides, a module control unit 340 that supplies the image source of the image source unit 330 to the LED panel 310 in frame units, the LED panel according to a predetermined brightness control signal applied from the outside. A brightness control unit 360 that outputs a brightness reference voltage value for controlling the brightness of the brightness control unit 360, and a D/A converter that converts the brightness reference voltage value of the digital value output from the brightness control unit 360 into the brightness reference voltage value of the analog value. Includes (370).

The brightness control unit 360 outputs a brightness reference voltage value for adjusting the brightness of the LED panel according to a predetermined brightness control signal applied from the outside. Here, the predetermined brightness control signal may be a remote control signal that can read different brightness reference voltage values for each season, day and night, time zone, and type of color image stored in a look-up table (not shown). That is, when a predetermined brightness control signal is applied to the brightness control unit 360 from the outside, the brightness control unit 360 reads different brightness reference voltage values for each day and night, time period, and type of color image stored in the look-up table 360. and print it out.

For example, when dividing into day and night, the brightness control unit 360 outputs a brightness reference voltage value so that the switching mode power supply can output 5 volts during the day, and so that the switching mode power supply can output 3.2 volts at night. The brightness control unit 360 can output a brightness reference voltage value.

In addition, when classifying color images by type, the brightness control unit 360 outputs a brightness reference voltage value so that the switching mode power supply can output 2.5 volts for the R LED, 3.2 volts for the G LED, and 3.0 volts for the B LED. can do.

In addition, when dividing by time zone, the brightness reference voltage value can be changed by dividing into day, evening, and night.

According to the present invention, the lookup table (not shown) is a solid state disk (SSD), a USB memory (Universal Serial Bus Memory; USB Memory), a Secure Digital card (SD), and a mini Secure Digital card (mini). Secure Digital card (mSD), Micro Secure Digital Card (micro SD), Secure Digital High Capacity (SDHC), Memory Stick Card, Smart Media Card (SM), Multi It can be implemented in a card format such as a media card (Multi Media Card (MMC)), embedded multi media card (Embedded MMC (eMMC)), or compact flash card (Compact Flash (CF)).

The memory 910 of this embodiment is ROM (Read Only Memory), NOR Flash Memory, NAND Flash Memory, PRAM (Phase Change Random Access Memory), RRAM (Resistive Random Access Memory), and MRAM (Magnetic Random Access Memory) with non-volatile characteristics. Access Memory), etc.

Meanwhile, since the forward voltage drop (VF) values of RGB are different, it is most advantageous to have three D/A converters, but if only one is installed, it is preferable to install the GREEN LED as the center.

The D/A converter 370 converts the brightness reference voltage value of the digital value output from the brightness control unit 360 into the brightness reference voltage value of the analog value.

In addition, the power-saving electronic signboard capable of automatic voltage adjustment according to another embodiment of the present invention may further include an illuminance sensor 350 that outputs an illuminance sensor signal that varies depending on the brightness of the external environment during day and night. At this time, the brightness control unit 360 can select and output one of the remote control signal and the illuminance sensor signal according to the selection command signal included in the predetermined brightness control signal.

Figure 4 is a circuit diagram of a switching mode power supply capable of voltage adjustment according to an embodiment of the present invention, and Figure 5 is a circuit diagram of main parts of a switching mode power supply capable of voltage adjustment according to an embodiment of the present invention.

A switching mode power supply capable of adjusting voltage according to an embodiment of the present invention includes a high-frequency PWM switching generator IC (410), a high-frequency transformer (420), a constant voltage IC (430), a voltage comparator (440), and a photocoupler (450). Includes.

The high-frequency PWM switching generator IC 410 receives a direct current voltage and generates a PWM switching signal whose pulse width is adjusted from several kilohertz to tens of kilohertz depending on the size of the output voltage fed back through the photocoupler 450.

When the PWM switching signal with the adjusted pulse width is applied to the FET (Q3, Q6) through the transistors (Q1, Q2, Q4, Q5), the high-frequency transformer 420 outputs a low voltage to the secondary side.

The constant voltage IC 430 outputs the low voltage output to the secondary side of the high frequency transformer 420 as a constant voltage of a predetermined size.

The voltage comparator 440 compares the secondary output voltage of the high-frequency transformer 420 with the brightness reference voltage of the analog value output from the D/A converter 370 and outputs a comparison value.

The photocoupler 450 includes a photodiode (PC1) that emits light according to the comparison value output from the voltage comparator 440 and a phototransistor (PC2) that outputs an optical comparison signal in response to the operation of the photodiode (PC1). do.

That is, when the secondary output voltage of the high frequency transformer 420 is input to the voltage comparator 440, the voltage comparator 440 calculates the secondary output voltage of the high frequency transformer 420 and the analog output voltage from the D/A converter 370. The comparison value is output by comparing the reference voltage of the value, and the secondary output voltage of the high-frequency transformer (420) is fed back to the high-frequency PWM switching generation IC (410) through the photocoupler (450) that operates according to the comparison value. By adjusting the driving switching width, the high-frequency transformer 420 can always output a constant voltage.

However, in the electronic sign lighting control system, the current flows the same, but lowering the voltage can have a power saving effect. For example, when the electric sign is operated with 3 volts, a 40% power saving effect occurs. To this end, according to the switching mode power supply of the present invention, a D/A converter 370 connected to I2C is installed to provide a reference voltage to the voltage comparator 440 to enable automatic voltage adjustment in the PWM method according to the display environment of the electronic signboard. do. Accordingly, the reference voltage of the voltage comparator 440 can be freely changed remotely, and multiple D/A converters 370 can be connected in parallel.

Because the D/A converter 370 is ultra-small in size, it can be mounted on a small PCB and placed outside or inside a switching mode power supply.

The embodiments described in this specification and the accompanying drawings merely illustratively illustrate some of the technical ideas included in the present invention. Accordingly, the embodiments disclosed in this specification are not intended to limit the technical idea of the present invention, but rather to explain it, and therefore, it is obvious that the scope of the technical idea of the present invention is not limited by these embodiments. All modifications and specific embodiments that can be easily inferred by a person skilled in the art within the scope of the technical idea included in the specification and drawings of the present invention should be construed as being included in the scope of the present invention.

310: LED panel
320: switching mode power supply
330: Video source unit
340: Module control unit
350: Illuminance sensor
360: Brightness control unit
370: D/A converter
410: High-frequency PWM switching generation IC
420: High frequency transformer
430: Constant voltage IC
440: Voltage comparator
450: Photocoupler

Claims (6)

In the electric signboard installed outdoors and configured to have a plurality of switching mode power supplies apply voltage to the LED panel,
the LED panel displaying an image source;
A video source unit providing a video source;
a module control unit that supplies the video source of the video source unit to the LED panel;
a brightness control unit that outputs a brightness reference voltage value for controlling the brightness of the LED panel according to a predetermined brightness control signal;
A D/A converter that converts a brightness reference voltage value of a digital value output from the brightness control unit into a brightness reference voltage value of an analog value; and
A power-saving electronic signboard capable of automatic voltage adjustment, comprising the plurality of switching mode power supplies that output an output voltage corresponding to the brightness reference voltage value output from the D/A converter to the LED panel.
In claim 1,
The predetermined brightness control signal is a remote control signal capable of reading different brightness reference voltage values for at least one of day and night, time zone, and color image type stored in the lookup table. Possible energy-saving electronic signboard.
In claim 2,
The lookup table includes solid state disk (SSD), USB memory (Universal Serial Bus Memory (USB Memory)), Secure Digital (SD), mini Secure Digital card (mSD), and micro Secure Digital Card (micro SD), Secure Digital High Capacity (SDHC), Memory Stick Card, Smart Media Card (SM), Multi Media Card (MMC) ), embedded multi-media card (Embedded MMC; eMMC), compact flash card (Compact Flash; CF), or ROM (Read Only Memory), NOR Flash Memory, NAND Flash Memory, or PRAM (Phase Change Random Access) A power-saving electronic sign board capable of automatic voltage regulation, characterized in that it is implemented in any one of Memory), RRAM (Resistive Random Access Memory), and MRAM (Magnetic Random Access Memory).
In claim 3,
An illuminance sensor that outputs an illuminance sensor signal that varies depending on the brightness of the external environment day and night.
A power-saving electronic signboard capable of automatic voltage regulation that further includes.
In claim 4,
The brightness control unit selects and outputs one of a remote control signal and an illumination sensor signal according to a selection command signal included in a predetermined brightness control signal.
The method of any one of claims 1 to 5, wherein the switching mode power supply,
A high-frequency PWM switching generator IC that receives a direct current voltage and generates a PWM switching signal whose pulse width is adjusted according to the optical comparison signal output from the photocoupler below;
a high-frequency transformer that outputs a low voltage to the secondary side when the PWM switching signal with the adjusted pulse width is applied to the switching element;
a constant voltage IC that outputs the low voltage output from the secondary side of the high-frequency transformer as a constant voltage of a predetermined level;
a voltage comparator that compares the secondary output voltage of the high-frequency transformer with a brightness reference voltage of the analog value output from the D/A converter and outputs a comparison value; and
A photocoupler including a photodiode that emits light according to the comparison value output from the voltage comparator and a phototransistor that outputs an optical comparison signal in response to the operation of the photodiode.
A power-saving electronic signboard capable of automatic voltage regulation including.

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