KR100957819B1 - Light emitting diode driving circuit and apparatus including the same - Google Patents

Abstract

PURPOSE: An LED(Light Emitting Diode) driving circuit and an LED device including the same are provided to minimize heat and an electromagnetic wave by controlling the brightness of the LED through a low frequency pulse width driving signal. CONSTITUTION: A power supply unit(100) comprises a battery comparator, a power controller and a power output terminal. The battery comparator generates a battery comparison signal by comparing an output voltage level of a plurality of output voltage levels. A power controller generates a battery control signal based on the battery comparison signal. The power output terminal supplies the battery power according to the battery control signal. A DC-DC converter(200) converts the battery power to the LED power suitable for the operation of the LED. A pulse width modulator(300) generates a pulse width modulation driving signal based on the LED power.

Description

Light Emitting Diode Driving Circuit and apparatus including the same

The present invention relates to a light emitting diode driving circuit, and more particularly, to provide a light emitting diode power supply through a plurality of batteries, and to generate a low frequency pulse width modulation driving signal to drive a light emitting diode. A light emitting diode device is included.

A light emitting diode (LED) is a type of PN junction diode that is a semiconductor device that converts and outputs infrared or light when voltage is applied in a forward direction. The light emitting diode generates light by an electroluminescence effect, and the color of the light emitting diode is determined by the wavelength of the generated light. The wavelength of light generated by the light emitting diode may be different depending on the material constituting the light emitting diode.

Light emitting diodes have a lower power consumption and faster response than incandescent bulbs and fluorescent lamps, and thus are expanding their application range. In general, a person does not notice when a light blinks above a certain frequency, so the lighting device blinks at regular intervals to reduce power consumption and prevent overload.

Although the light emitting diode may be driven by applying a high frequency signal using the characteristics of a light emitting diode having a fast blink rate, electromagnetic waves generated by the electromagnetic induction caused by the high frequency signal negatively affect the health of the user.

In the case of a light emitting diode illumination device that maintains a constant color and brightness, it does not need to be driven through a high frequency signal because display information does not change like a display device. In addition, the user cannot recognize illuminance over a certain range, and the excess current is emitted as heat when the threshold value is reached due to the characteristics of the diode. Therefore, unnecessary current consumption and heat is required when driving a light emitting diode with direct current. Incidence will increase.

One object of the present invention for solving the above problems is to provide a light emitting diode driving circuit that can reduce the occurrence of chattering due to replacement of the rechargeable battery, and minimize the power consumption.

Another object of the present invention is to provide a light emitting diode device including a light emitting diode driving circuit capable of minimizing electromagnetic waves and heat generation by generating a low frequency pulse width driving signal to adjust the brightness of the light emitting diode.

In order to achieve the above object, the LED driving circuit according to an embodiment of the present invention includes a power supply, a DC-DC converter, and a pulse width modulator. The power supply unit detects detached states and output voltage levels of a plurality of batteries and selects a power supply battery among the plurality of batteries to provide battery power. The DC-DC converter converts the battery power into a light emitting diode power suitable for the operation of the light emitting diode. The pulse width modulator generates a pulse width modulation driving signal having a frequency of 1 kHz or less based on the LED power supply.

In one embodiment, the power supply unit may include a battery bank, a battery comparator, a power controller, and a power output terminal. The battery bank may include the plurality of batteries, respectively, and may include a plurality of battery units configured to activate a battery confirmation signal and a battery discharge detection signal by sensing a detached state and an output voltage level of the battery. The battery comparator may generate a battery comparison signal by comparing output voltage levels of the plurality of batteries. The power controller may generate a battery control signal based on the battery confirmation signal, the battery discharge detection signal, and the battery comparison signal. The power output terminal may select one of the plurality of batteries as the power supply battery in response to the battery control signal to provide an output voltage of the power supply battery as battery power. Each of the plurality of battery units may include the battery, a discharge detector, and a battery checker. The battery is removable and may provide the output voltage. The battery may be charged by a four-terminal network circuit, and a plurality of batteries may be charged at the same time through several channels. The discharge detector may activate the battery discharge detection signal when the output voltage level received from the battery is equal to or less than a preset voltage level, and the battery checker determines whether the battery is detached in response to the output voltage. The battery confirmation signal can be activated. For example, the battery confirmation signal may be activated when a battery is mounted in the battery units.

In example embodiments, the discharge detection unit may include a first discharge detection circuit and a second discharge detection circuit. The first discharge detection circuit may activate the first battery discharge detection signal when the output voltage has a voltage level lower than the first voltage by comparing the output voltage with the first voltage, and the second discharge detection circuit. May compare the output voltage with a second voltage having a lower voltage level than the first voltage, and activate the second battery discharge detection signal when the output voltage has a lower voltage level than the second voltage. For example, the first battery discharge detection signal may be activated before the second battery discharge detection signal. The power control unit may generate the battery control signal based on the battery comparison signal and the first battery discharge detection signal.

The battery checker may activate a battery check signal and activate a battery discharge detection initialization signal in response to the battery check signal when the output voltage level of the battery is equal to or greater than a preset voltage level. The battery discharge detection initialization signal may be initialized by being set to a logic state 'low' and may be activated to correspond to a logic state 'high'. For example, the pulse width modulator may adjust brightness of the light emitting diode by adjusting a duty ratio of the pulse width modulated driving signal.

The LED driving circuit may further include a driving controller which receives a command signal from an external source, converts the command signal into a signal suitable for driving the LED, and generates a control signal, wherein the battery control signal is the control signal. Can be generated based on

In order to achieve the above another object, a light emitting diode device according to an embodiment of the present invention includes a light emitting diode driving circuit and a light emitting diode unit. The LED driving circuit detects detached states and output voltage levels of a plurality of batteries to select a power supply battery among the plurality of batteries, and generates a pulse width modulation driving signal having a frequency of 1 kHz or less based on the power supply battery. Create The light emitting diode unit includes a plurality of light emitting diodes that emit light in response to the pulse width modulation driving signal. The light emitting diode driving circuit may control the brightness of the plurality of light emitting diodes by adjusting a duty ratio of the pulse width modulation driving signal.

The LED driving circuit according to an exemplary embodiment of the present invention can supply battery power without detecting chattering by detecting detached states and discharges of a plurality of batteries, and generating a low frequency pulse width modulation driving signal to generate an appropriate number of LEDs. Current consumption and heat generation can be reduced while maintaining brightness.

A light emitting diode device according to an embodiment of the present invention selects a power supply battery according to the voltage level of a plurality of batteries, generates a low frequency pulse width modulation driving signal that does not generate electromagnetic waves, and drives a plurality of light emitting diodes to drive at low power. It is possible to minimize heat generation and improve portability.

With respect to the embodiments of the present invention disclosed in the text, specific structural to functional descriptions are merely illustrated for the purpose of describing embodiments of the present invention, embodiments of the present invention may be implemented in various forms and It should not be construed as limited to the embodiments described in.

As the inventive concept allows for various changes and numerous modifications, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between. Other expressions describing the relationship between components, such as "between" and "immediately between," or "neighboring to," and "directly neighboring to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof that is described, and that one or more other features or numbers are present. It should be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. .

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a view showing a light emitting diode driving circuit according to an embodiment of the present invention.

Referring to FIG. 1, the LED driving circuit may include a power supply unit 100, a DC-DC converter 200, and a pulse width modulator 300.

The power supply unit 100 may include a plurality of batteries, and the plurality of batteries may be implemented in a removable form. The power supply unit 100 determines whether the batteries are attached or detached, and determines a battery to supply power by grasping the discharge degree of the batteries. Whether the batteries are detached or discharged may be determined based on output voltage levels provided by the batteries. When one of the plurality of batteries provides the battery power BAT_POWER required for driving the light emitting diode, the other batteries may be provided and charged in the charger. According to an embodiment, the charger may be implemented separately from the light emitting diode circuit, or the 4-terminal charging bank 150 may be included in the light emitting diode. Accordingly, the plurality of batteries may alternately provide battery power (BAT_POWER) to the light emitting diodes, thereby improving a problem in that the light emitting diodes cannot be driven due to the lack of a power battery due to the discharge of the batteries. The power supply unit 100 provides the battery power BAT_POWER to the DC-DC converter 200.

The DC-DC converter 200 converts the battery power BAT_POWER into the light emitting diode power LED_VDD required for driving the light emitting diode. The light emitting diode power LED_VDD may have a preset voltage level. For example, when the battery power source BAT_POWER has a voltage level of 20V, the LED power source LED_VDD may be provided by step-down converting about 12V.

The pulse width modulation unit 300 receives the light emitting diode power supply LED_VDD and generates a pulse width modulation driving signal LED_DR having a constant duty ratio. The frequency of the pulse width modulation driving signal LED_DR has a frequency value that is too low for a person to recognize that the light emitting diode is blinking, and may have a value between 60 Hz and 1 kHz, for example.

The light emitting diode emits light in response to the pulse width modulation driving signal driving signal LED_DR, and the brightness of the light emitting diode is controlled by the duty ratio of the pulse width modulation driving signal LED_DR. That is, the duty ratio is determined by the time when the pulse width modulation driving signal LED_DR corresponds to the logic state 'high' and the time corresponding to the logic state 'low'. Corresponds to the time that is turned off. Therefore, when the duty ratio of the pulse width modulation driving signal LED_DR is controlled, the time at which the LED is turned on and turned off is controlled. The longer the turn-on time of the LED is turned on during the time that the user cannot recognize, the brightness of the entire LED becomes brighter.

According to the embodiment. The LED driving circuit can further include a drive controller 400. The driving controller 400 receives the command signal CMD from the outside, such as a host, and generates a control signal CON. The control signal CON may be provided to the power supply unit 100, the DC-DC converter 200, and the pulse width modulator 300. The control signal CON may differently adjust the reference for selecting the battery power from the power supply unit 100, and adjust the voltage level of the light emitting diode power LED_VDD step-down converted in the DC-DC converter 200. Can be. In addition, the duty ratio of the pulse width modulation driving signal LED_DR generated by the pulse width modulator 300 may be adjusted. The drive controller 400 may function as an interface for converting the command signal CMD from the outside into a control signal CON suitable for the operation of the LED driving circuit.

FIG. 2 is a block diagram illustrating the power supply unit of FIG. 1.

Referring to FIG. 2, the power supply unit 100 may include a power controller 110, a battery bank 120, a battery comparator 130, and a power output terminal 140, and the battery bank 120 may include a plurality of batteries. It may include the parts (121a, 121b, 121n).

The power controller 110 may receive a control signal CON from the driving controller 400 of FIG. 1 to set a criterion for selecting a plurality of battery units included in the battery bank 120. For example, the battery comparison signal CMP may be received to select a battery having the highest output voltage level among the plurality of batteries as a supply battery to secure time for charging batteries having a low output voltage, or The supply battery selection method can be set by selecting the lowest battery as the supply battery, discharging it first, and then charging the battery. The power controller 110 receives the battery confirmation signal BAT_IN and the battery discharge detection signal Q_BAT from the battery units 121a, 121b, and 121n included in the battery bank 120, respectively, and from the battery comparator 130. The battery comparison signal CMP is received to generate a battery control signal BAT_CON.

The battery bank 120 may include a plurality of battery units 121a, 121b,, 121n. The plurality of battery units 121a, 121b, and 121n may generate the battery confirmation signal BAT_IN and the battery discharge detection signal Q_BAT, respectively. The battery confirmation signal BAT_IN indicates a detached state of the battery, and the battery discharge detection signal Q_BAT is activated when the voltage level of the battery is lower than or equal to a preset voltage level to indicate whether the battery is discharged.

The battery comparator 130 generates a battery comparison signal CMP by comparing the output voltage levels BATs of the plurality of batteries included in the battery bank 120. The battery comparison signal CMP is provided to the power controller 110 and serves as a basis for generating the battery control signal BAT_CON. The battery comparison signal CMP senses and compares output voltage levels BATs of the batteries. For example, the battery comparison signal CMP may include battery information having the highest output voltage level among all batteries or an output voltage level ratio between batteries. According to an embodiment, the battery comparison signal CMP may have a value obtained by dividing each battery output voltage level by the sum of total battery output voltages. In addition, when the battery bank 120 includes two battery units, the battery comparison signal CMP may be a value obtained by dividing one battery output voltage level by another battery output voltage level. The power controller 110 may generate a battery control signal BAT_CON based on the battery comparison signal CMP. However, the criterion for selecting the battery may be different based on the control signal CON. That is, the battery having the highest output voltage level among the plurality of batteries is selected as a power supply battery to maximize battery life, or the battery having the lowest output voltage level is selected as a power supply battery and discharged first, thereby requiring charging. Can sort out the batteries.

The power output terminal 140 selects one of the plurality of batteries as a power supply battery based on the battery control signal BAT_CON and provides an output voltage of the power supply battery to the battery power POWER_BAT. For example, the power output terminal 140 may be composed of switches connected to the plurality of battery units 121a, 121b, and 121n, respectively, and the output terminal connected to the selected power supply battery in response to the battery control signal BAT_CON. By connecting, it can be provided as battery power (POWER_BAT).

According to an embodiment, the power supply unit 100 may further include a four-terminal charging bank 150.

The four-terminal charging bank 150 includes a four-terminal charging unit connected to the corresponding battery units 121a, 121b, and 121n included in the battery bank 120 to charge the plurality of batteries.

The four-terminal charging bank 150 may charge the battery using a DC power supplied from the outside based on the battery output voltage BAT and the output current. The charging operation of the four-terminal charging bank 150 will be described later.

3 is a block diagram illustrating a battery unit of FIG. 2.

Referring to FIG. 3, the battery unit 121 may include a battery 123, a discharge detector 125, and a battery check unit 127.

The battery 123 may be any voltage providing device capable of charging, and the battery 123 may be detachable and the battery detachment state is confirmed by the battery checker 127. The detached state may be detected by sensing the output voltage level of the batteries.

The battery 123 may be charged by a charging bank having a four terminal network. Through the four-terminal network, the input voltage, input current, output voltage, and output current provided to the battery can be measured to control heat generation based on the current output voltage and output current of the battery and to check the degree of charge. In addition, the charging operation of the plurality of batteries is respectively controlled, and the plurality of batteries may be simultaneously charged.

The discharge detector 125 detects the output voltage level of the corresponding battery 123 to activate the battery discharge detection signal Q_BAT. The discharge detector 125 activates the battery discharge detection signal Q_BAT when the voltage level is lower than the preset voltage level due to the output voltage of the battery 123 being provided to the light emitting diode. The battery discharge detection signal Q_BAT may include a first battery discharge detection signal Q_BAT_1 and a second battery discharge detection signal Q_BAT_2, and the preset voltage level may be about 4.2V. When the battery discharge detection signal Q_BAT is activated, it is determined that the output voltage of the corresponding battery 123 is discharged to the extent that the light emitting diode cannot be driven, and the output voltage of the battery 123 is discharged to operate the light emitting diode. In order to prevent this from being stopped, the power output unit 140 may be controlled by the power controller 110 to use another battery. However, in the present invention, instead of selecting the power supply battery among the batteries by the single battery discharge detection signal Q_BAT, the battery output voltage level is sensed based on reference voltages having different voltage levels for the discharge determination. The battery discharge detection signal Q_BAT_1 is activated first, and then the second battery discharge detection signal Q_BAT_2 is activated. Therefore, the first battery discharge detection signal Q_BAT_1 is activated before all of the batteries are discharged to use another battery as the power supply battery so that the light emitting operation of the light emitting diode can be continuously driven without stopping.

The battery checking unit 127 checks whether the corresponding battery 123 is currently mounted in the battery unit 121. In addition, when the battery 123 is detached and reattached, the battery checker 127 activates the battery discharge detection initialization signal Q_RST to initialize the discharge detector 125. By initializing the discharge detector 125, the previous battery discharge detection signal Q_BAT is initialized to a logic state 'low'.

4 is a circuit diagram illustrating an example embodiment of the discharge detector of FIG. 3.

Referring to FIG. 4, the discharge detector 125 may include a first discharge detection circuit 1251, a second discharge detection circuit 1253, and a flip flop 1255.

The first comparator CP1 included in the first discharge detection circuit 1251 has a voltage level of the fourth node ND4 when the voltage level of the first node ND1 is lower than that of the second node ND2. Activate to correspond to the logic state 'high'. However, the voltage level of the fourth node ND4 does not have a constant value according to the output voltage level of the battery, corresponding to the threshold value before discharge, and fluctuates between logic state 'high' and logic state 'low'. can do. Therefore, when the voltage level of the first node ND1 is lower than the voltage level of the second node ND2, the first discharge detection circuit 1251 fluctuates the voltage level of the fourth node ND4. However, when the voltage level of the first node ND1 is substantially the same as the voltage level of the second node ND2, the voltage level of the fourth node ND4 fluctuates unstablely and is flip-flop with the clock signal CLK. Provided at 1255. The timing at which the clock signal CLK is generated may correspond to the timing at which the battery output voltage level reaches near the threshold. Accordingly, the first battery discharge detection signal Q_BAT_1 may be activated when the output voltage level of the battery reaches near the voltage level of the second node ND2.

The second comparator CP2 included in the second discharge detection circuit 1253 may have a voltage level of the fifth node ND5 when the voltage level of the first node ND1 is lower than that of the third node ND3. Activate to correspond to the logic state 'high'. Therefore, when the voltage level of the first node ND1 is lower than the voltage level of the third node ND3, the second discharge detection circuit 1253 corresponds to the logic state 'high' when the voltage level of the fifth node ND5 is lower than that of the third node ND3. The second battery discharge detection signal Q_BAT_2 is activated.

Since the voltage level of the third node ND3 is lower than that of the second node ND2, the voltage level of the fourth node ND4 of the first discharge detection circuit 1251 is the voltage of the fifth node ND5. Change before the level. That is, the voltage level of the fourth node ND4 may first trigger between the logic state 'high' and the logic state 'low'. In general, the voltage level corresponding to the reference voltage for determining the discharge of the battery 123 may be the voltage level of the third node ND3. However, if the LED is driven based on the output voltage of another battery after one battery is discharged, it is impossible to continuously drive the LED by flashing the LED in the process of replacing power with another battery. Can be. Accordingly, the power supply battery which generates the first battery discharge detection signal Q_BAT_1 based on the voltage level of the second node ND2 having a voltage level higher than that of the third node ND3 to drive the current light emitting diode. Replace to allow the LED to be driven continuously. When the voltage level of the fourth node ND4 fluctuates, it may occur when the voltage level of the battery 123 passes near a preset state to determine whether the battery is discharged. The flip-flop 1255 uses the voltage level of the fourth node ND4 as the clock signal CLK and provides the power supply voltage VDD as the first battery discharge detection signal Q_BAT_1 in response to the clock signal CLK. . Accordingly, the first battery discharge detection signal Q_BAT_1 is generated at a time earlier than the time at which the output voltage of the battery 123 may be judged to be completely discharged so that the LED may be continuously driven.

The second battery discharge detection signal Q_BAT_2 is activated when the voltage level of the first node ND1 is lower than the voltage level of the third node ND3. Therefore, the second battery discharge detection signal Q_BAT_2 may be activated later than the first battery discharge detection signal Q_BAT_1.

The flip flop 1255 may be implemented as logic gate devices, and activates the first battery discharge detection signal Q_BAT_1 in response to the voltage level of the fourth node ND4. In addition, the first battery discharge detection signal Q_BAT_1 is initialized in response to the battery discharge detection initialization signal Q_RST received from the battery checking unit 127.

The discharge detector 125 detects a case where the output voltage level of the battery 123 is lower than a preset value and provides the battery discharge detection signal Q_BAT to the power controller 110 to thereby generate a light emitting diode among the plurality of batteries. Allows you to select the power supply battery to drive.

FIG. 5 is a circuit diagram illustrating an example embodiment of the battery check unit of FIG. 3.

Referring to FIG. 5, the battery checker 127 may include a first comparator CP1, first to fifth resistors R51, R52, R53, R54, and R55, and a capacitor C51.

The battery checker 127 receives the battery output voltage BAT to generate a battery check signal BAT_IN and a battery initialization signal Q_RST.

The first comparator CP1 receives the battery output voltage BAT through a non-inverting terminal, and receives a voltage in which the power supply voltage VDD is allocated by the second and third resistors R52 and R53 to the inverting terminal. Accordingly, the battery check signal BAT_IN is activated when the battery output voltage BAT is higher than or equal to the preset voltage level by comparing the voltage level of the inverting terminal with the voltage level of the battery output voltage BAT. In addition, since a momentary change occurs in the battery output voltage BAT when the battery is removed and reattached, charge is supplied through the capacitor C51 to activate the battery discharge detection initialization signal Q_RST.

The battery checking unit 127 checks whether the plurality of batteries are mounted in the light emitting diode or the battery unit 121 is not mounted because the battery unit 121 is provided to another device and is in a charged state. In addition, when it is determined that the battery is discharged by the discharge detector 125, since the battery discharge detection signal Q_BAT is activated as described above, when the battery 123 is newly charged and mounted in the battery unit 120, Since it is necessary to detect the discharge again by initializing the battery discharge detection signal Q_BAT, the battery discharge initialization signal Q_RST is activated and provided to the discharge detection unit 125. The battery discharge detection signal Q_BAT of the discharge detection unit 125 is initialized in an inactive manner in response to the battery discharge initialization signal Q_RST. For example, the battery discharge detection signal Q_BAT may be deactivated to correspond to the logic state 'low'.

6 is a view for explaining the operation of the LED driving circuit according to an embodiment of the present invention.

2 to 6, the operation of the LED driving circuit according to an embodiment of the present invention will be described.

BAT is a battery output voltage, BAT_IN is a battery confirmation signal, Q_RST is a battery discharge detection initialization signal, Q_BAT_1 is a first battery discharge detection signal, and Q_BAT_2 is a second battery discharge detection signal.

At the time t1, the battery 123 is mounted in the battery unit 121, and when the output voltage BAT of the battery 123 is higher than the preset voltage level, the battery check unit 127 may provide the battery check signal BAT_IN. The battery discharge detection initialization signal Q_RST is activated. In response to the battery discharge detection initialization signal Q_RST, the first and second battery discharge detection signals Q_BAT_1 and Q_BAT_2 are initialized to a logic state 'low'. When the LED is driven based on the mounted battery 123, when a predetermined time elapses, charge of the battery 123 is consumed to reduce the output voltage level, and at time t2, the second node ND2 of FIG. 4. The battery output voltage BAT is smaller than the voltage of Vc, so that the first battery discharge detection signal Q_BAT_1 is activated. In response to the first battery discharge detection signal Q_BAT_1, the power controller 110 generates a battery control signal BAT_CON for selecting a battery other than the power supply battery currently being used as the power supply battery to generate a power output terminal ( 140).

After the first battery discharge detection signal Q_BAT_1 is activated, the second battery discharge detection signal Q_BAT_2 may be activated at a time t3. Therefore, although the battery 123 is not completely discharged between the time t2 and the time t3, the discharge time is expected. At this time, another LED is selected as the power supply battery to supply the battery power (POWER_BAT). It is possible to prevent the chattering (chattering) that is flickering can drive the light emitting diode continuously even if one battery is discharged.

7A is a diagram conceptually illustrating a four-terminal charging unit according to an exemplary embodiment of the present invention.

Referring to FIG. 7A, the four-terminal charging unit may include first and second input terminals IN1 and IN2 and first and second output terminals OUT1 and OUT2. The first and second input terminals IN1 and IN2 may be provided by a switching mode power supply (SMPS) that converts AC power into input charging terminals for charging the battery 123 and provides DC power. have. The first and second output terminals OUT1 and OUT2 may correspond to both ends of the positive electrode and the negative electrode of the battery 123.

The voltage between the first and second input terminals IN1 and IN2 is the first voltage V1, and the voltage between the first and second output terminals OUT1 and OUT2 is the second voltage V2 and the first voltage. The current input to the input terminal IN1 is referred to as the first current I1 and the current output from the first output terminal is referred to as the second current I2. The first voltage V1 may correspond to an input voltage, the second voltage V2 may correspond to an output voltage, the first current I1 may correspond to an input current, and the second current I2 may correspond to an output current.

V1 is the input voltage, V2 is the output voltage, I2 is the output current, and A and B are the transmission parameters.

Where I1 is the input current and C and D are the transmission parameters.

In Equation 1, when the secondary side is opened so that the output current I2 becomes 0, the transmission parameter A is expressed by Equation 3 below.

In Equation 1, when the secondary side is shorted and the output voltage V2 becomes 0, the transmission parameter B is expressed by Equation 4.

In addition, when the secondary side is opened in Equation 2 such that the output current I2 becomes 0, the transmission parameter C is expressed by Equation 5.

In Equation 2, when the secondary side is shorted and the output voltage V2 becomes 0, the transmission parameter D is represented by Equation 6.

According to the present invention, the transmission parameters A and B are calculated and stored based on Equations 3 and 4 at any time, and the output voltage V2 and the output current I2 are substituted into Equation 1 to input voltage. (V1) is calculated.

Similarly, at any point in time, the transmission parameters C and D are calculated and stored based on Equations 5 and 6, and the output voltage V2 and the output current I2 are substituted into Equation 2 to obtain the input current ( Calculate I1).

The transmission parameters A, B, C, and D may be calculated to sense the output voltage and output current of the plurality of batteries at any time and charge the plurality of batteries simultaneously. In other words, by detecting the output voltage and output current of each battery 123 to calculate the input voltage and input current to control to supply a constant input voltage and input current to the battery 123, by detecting the battery output voltage and output current Battery charging may be controlled by determining whether the batteries are all charged and whether an overcurrent flows.

FIG. 7B is a diagram illustrating a four-terminal charge bank of FIG. 1.

Referring to FIG. 7B, the four-terminal charging bank 150 may include a plurality of four-terminal charging units 151a, 151b,, 151n, and a charging control unit 153. Each of the four terminal chargers 151a, 151b, and 151n may include a battery input detector 1511 and a battery output detector 1513. The battery input detector 1511 detects an input voltage and an input current provided to a corresponding battery for charging, and the battery output detector 1513 outputs a battery output voltage BAT and an output current from the corresponding battery 123. Detect it.

As described with reference to FIG. 7A, the plurality of four-terminal charging units 151a, 151b, and 151n may input the input voltage, the input current, the output voltage, and the output current to calculate transmission parameters of the respective batteries at an arbitrary time point. It detects and provides it to the charging control unit 153. The charging control unit 153 detects an input voltage, an input current, an output voltage, and an output current of each battery to calculate and store transmission parameters.

Transmission parameters for each battery are stored in the charging control unit 153 to sense the battery output voltage and output current to control each battery input voltage and input current, and determine whether the battery is charged based on the battery output voltage. can do. That is, the output voltage and the output current may be sensed, and the input voltage and the input current may be calculated based on the transmission parameter, and the input voltage and the input current may be controlled to have a constant value. In this case, the battery may be determined to be charged and may not provide an input voltage and an input current. Therefore, the charging control unit 153 may have different transmission parameters for each battery and control the respective batteries. Also, the charging control unit 153 may perform the charging operation only on the batteries selected by the control of the charging control unit 153. In general, the battery discharge signal Q_BAT may be performed on activated batteries.

8 is a diagram illustrating a pulse width modulator according to an exemplary embodiment of the present invention.

The pulse width modulator 300 receives the LED power supply voltage LED_VDD converted to be suitable for driving the LED in the DC-DC converter 200 and generates a pulse width modulation driving signal LED_DR.

The pulse width modulator 300 includes first and second comparators CP1 and CP2, first through sixth resistors R71, R72, R73, R74, R75, and R76, and first and second capacitors C71, C72), transistor Q1, and flip flop FF. The pulse width modulator 300 may be implemented using the NE555 chip.

The period and duty ratio of the pulse width modulator 300 is determined based on the values of the first to third resistors R71, R72, and R73 and the first capacitor C71.

The pulse width modulation driving signal LED_DR has a predetermined period, and the duty ratio is adjusted according to the brightness of the light emitting diode to be driven. For example, when the brightness of the light emitting diode is increased, the turn-on time of the light emitting diode should be increased, so the duty ratio is changed by increasing the turn-on time of the light emitting diode, and when the brightness of the light emitting diode is decreased, the turn- Increase the time it is off. That is, the light emitting diode is turned on in the section where the light emitting diode driving signal LED_DR corresponds to the logic state 'high', and the light emitting diode is turned on in the section where the light emitting diode driving signal LED_DR corresponds to the logic state 'low'. Since it is turned off, the period of the LED driving signal LED_DR is kept constant, but the brightness may be adjusted by adjusting the turn-on and turn-off time in one cycle. In the case where the constant DC power is continuously applied, the brightness of the light emitting diode becomes saturated at a predetermined size, unnecessary current flows, and heat generation also increases. However, the user does not need to continuously turn on the LED without blinking because the LED does not recognize when the LED blinks above a certain frequency, and has a constant period by providing a pulse width modulation driving signal (LED_DR). By turning on and off the LEDs, the desired brightness can be controlled to reduce current consumption and heat generation. The user recognizes that the LED emits light continuously when the LED blinks at a frequency of 60 Hz or more.

In one embodiment, when driving the light emitting diode, even if the DC-DC converter 200 is provided with the same voltage of 12V, without applying the pulse width modulator 300, when applying the DC voltage to the light emitting diode as it is Although a current of about 420 mA flows, when the pulse width modulation driving signal LED_DR is generated through the pulse width modulator 300 to drive the light emitting diode, the light emitting diode may be driven with a current of about 280 mA. Therefore, it is possible to reduce the current consumption by driving the light emitting diode with a small current, so it is possible to increase the time to drive the light emitting diode with the same capacity battery, and the heat generated by the current is reduced, so that it is separate for heat treatment. Reduced components Accordingly, the LED device can be miniaturized and battery life is increased.

In addition, when the light emitting diode device is provided with a constant brightness, when driving the light emitting diode through a drive signal having a high frequency, electromagnetic waves may occur. Since electromagnetic waves adversely affect the human body, a light emitting diode lighting device that does not display a special image by adjusting brightness does not need to generate a driving signal having a higher frequency than necessary. When the pulse width modulation driving signal LED_DR is generated to have a low frequency of 1 kHz or less, it is possible to minimize the generation of electromagnetic waves within a range in which the user does not recognize the blinking of the light emitting diode.

9 is a diagram illustrating a pulse width modulation driving signal generated by a pulse width modulator according to an exemplary embodiment of the present invention.

Referring to FIG. 9, the pulse width modulation driving signal LED_DR has a period of T0, T1 is a time corresponding to logic state 'high', and T2 is a time corresponding to logic state 'low'. The light emitting diode is turned on during the T1 time, and the light emitting diode is turned off during the T2 time. The period T0 of the pulse width modulation driving signal LED_DR may have a constant value. For example, T0 may be 1 ms or more so that the pulse width modulation driving signal LED_DR may have a frequency of 1 kHz or less. T1 and T2 time may vary differently depending on the brightness of the light emitting diode. According to the ratio of the T1 and T2 times, the duty ratio of the pulse width modulation driving signal LED_DR becomes different, and the duty ratio can be controlled based on the control signal CON generated by the driving controller 400 of FIG. 1. have. For example, when increasing the brightness of the light emitting diode, it is possible to increase the time T1. Depending on the duty ratio, the magnitude of the current flowing through the light emitting diode may also be different.

10 is a view showing a light emitting diode device according to an embodiment of the present invention.

Referring to FIG. 10, the light emitting diode device 900 may include a light emitting diode driving circuit 910 and a light emitting diode unit 920.

The LED driving circuit 910 includes a power supply unit, a DC-DC converter, a pulse width modulator, and a driving controller to provide the pulse width modulation driving signal LED_DR to the light emitting diode unit 920.

The LED driving circuit 910 can generate a pulse width modulation driving signal LED_DR having a low frequency by including a plurality of rechargeable batteries. A plurality of rechargeable batteries are included in the power supply and are removable. Accordingly, the power supply may generate the pulse width modulation driving signal LED_DR even when only at least one battery is attached to the power supply, and the power supply may provide an output voltage such that the battery can drive the light emitting diode. It is possible to detect whether it is possible to drive a light emitting diode using the output voltage of another battery before having a value below a predetermined voltage, which may occur when the output voltage of another battery is used after all the batteries are discharged. Flickering of the light emitting diode can be prevented.

The batteries provided to the power supply may be charged by the four terminal charging bank. The 4-terminal charging bank is connected to the positive and negative electrodes of the battery to measure input voltage and input current, and to measure the output voltage and output current to detect the charge level of the battery, and to charge multiple batteries simultaneously. have.

The light emitting diode unit 920 may include a plurality of light emitting diodes, and emits light in response to the pulse width modulation driving signal LED_DR. By repeating the turn-on and turn-off operations based on the pulse width modulation driving signal LED_DR, the light emitting diodes maintain a predetermined brightness and reduce unnecessary current consumption and heat generation, and increase the lifespan of the light emitting diodes. You can. Since the pulse width modulation driving signal LED_DR has a low frequency, the light emitting diodes may have a longer period than they are driven by a high frequency signal, and thus may be controlled while the brightness is controlled. Since the pulse width modulation driving signal LED_DR has a low frequency, electromagnetic waves generated when driving the light emitting diode may be reduced.

The light emitting diode driving circuit according to the present invention selects a power supply battery using a plurality of batteries to supply power to provide a power supply, so that even when the battery is discharged, the light emitting diode can be continuously driven, thereby being driven by a battery. It can be used in the device.

In addition, the LED driving circuit according to the present invention can generate a low frequency pulse width modulation driving signal to drive the light emitting diode to reduce the generation of electromagnetic waves, it can be used in a light emitting diode device that can protect user health.

While the present invention has been described with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined in the appended claims. It will be understood.

1 is a view showing a light emitting diode driving circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating the power supply unit of FIG. 1.

3 is a block diagram illustrating a battery unit of FIG. 2.

4 is a circuit diagram illustrating an example embodiment of the discharge detector of FIG. 3.

FIG. 5 is a circuit diagram illustrating an example embodiment of the battery check unit of FIG. 3.

6 is a view for explaining the operation of the LED driving circuit according to an embodiment of the present invention.

7A is a diagram conceptually illustrating a four-terminal charging unit according to an exemplary embodiment of the present invention.

FIG. 7B is a diagram illustrating a four-terminal charge bank of FIG. 1.

8 is a diagram illustrating a pulse width modulator according to an exemplary embodiment of the present invention.

9 is a diagram illustrating a pulse width modulation driving signal generated by a pulse width modulator according to an exemplary embodiment of the present invention.

10 is a view showing a light emitting diode device according to an embodiment of the present invention.

Claims (14)

A power supply unit which detects detached states and output voltage levels of a plurality of batteries and selects a power supply battery among the plurality of batteries to provide battery power; A DC-DC converter converting the battery power into a light emitting diode power suitable for operation of the light emitting diode; And A pulse width modulator configured to generate a pulse width modulated driving signal having a predetermined frequency based on the light emitting diode power source; The power supply unit A battery bank including each of the plurality of batteries, the battery bank including a plurality of battery units sensing a detached state and an output voltage level of the battery to activate a battery confirmation signal and a battery discharge detection signal; A battery comparator configured to compare output voltage levels of the plurality of batteries to generate a battery comparison signal; A power controller configured to generate a battery control signal based on the battery confirmation signal, a battery discharge detection signal, and a battery comparison signal; And And a power output stage configured to select one of the plurality of batteries as the power supply battery in response to the battery control signal and to provide an output voltage of the power supply battery to battery power. The LED driving circuit of claim 1, wherein the preset frequency is 60 Hz or more and 1 kHz or less. delete The method of claim 1, wherein each of the plurality of battery units A battery which is detachable and provides the output voltage; A discharge detector activating the battery discharge detection signal when the output voltage level is less than or equal to a preset voltage level; And And a battery checker configured to determine whether the battery is attached or detached in response to the output voltage and to activate the battery check signal. The method of claim 4, wherein the discharge detection unit A first discharge detection circuit for activating a first battery discharge detection signal when the output voltage has a voltage level lower than the first voltage by comparing the output voltage with the first voltage; And A second discharge detection circuit that activates a second battery discharge detection signal when the output voltage has a voltage level lower than the second voltage by comparing the output voltage with a second voltage having a voltage level lower than the first voltage Light emitting diode driving circuit comprising a. The light emitting device of claim 4, wherein the battery checker activates a battery check signal and activates a battery discharge detection initialization signal in response to the battery check signal when the level of the output voltage is equal to or greater than a preset voltage level. Diode driving circuit. According to claim 1, And a four terminal charging bank configured to charge the plurality of batteries based on output voltages and output currents of the plurality of batteries. The method of claim 7, wherein the four-terminal charge bank is A plurality of charging units respectively connected to the plurality of battery units and sensing input voltages and input currents provided to the plurality of batteries and output voltages and output currents of the plurality of batteries at any time; And Calculating transmission parameters based on an input voltage and an input current provided to the plurality of batteries and an output voltage and an output current of the plurality of batteries, storing the calculated transmission parameters, and based on the stored transmission parameters A light emitting diode driving circuit comprising a charging control unit for controlling the state of charge of the plurality of batteries. The method of claim 8, wherein the charging control unit Derive an input voltage and an input current provided to the plurality of batteries based on the transmission parameters and output voltages and output currents of the plurality of batteries to control the input voltage and the input current provided to the plurality of batteries; And determining whether the plurality of batteries are charged based on the output voltages of the plurality of batteries. The light emitting diode driving circuit of claim 2, wherein the pulse width modulating unit adjusts a duty ratio of the pulse width modulation driving signal to adjust brightness of the light emitting diode. delete delete delete delete

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