KR101056046B1 - Led circuit with charging capability and providing method thereof - Google Patents

Abstract

PURPOSE: An LED circuit having a charge function and a providing method thereof are provided to maintain that LEDs keep over the constant brightness by selecting a drive cycle based on the time in which current is flowing after turning off the LEDs. CONSTITUTION: A driver(120) drives a plurality of LEDs. A plurality of charger circuits is connected to a plurality of LEDs in parallel. Charging is completed in case one LED among the plurality of LEDs is turn on. Current is flowed in the LED in case the LED is turn off. A controller outputs a control signal for selectively driving a plurality of LEDs to the driver. A detection part detects the current when selected one or more LEDs are turned off and outputs to the controller. The controller turns on one and more LEDs among the selected LEDs and turns off and measures a first reference rate duration about one or more first LED based on the received signal from the detection part. A standards drive cycle of a plurality of LEDs is determined based on the measured first reference rate duration.

Description

LED circuit with charging function and providing method thereof {LED Circuit with Charging Capability and providing method

The present invention uses a small number of drive circuits or control pins in a device including a plurality of light-emitting diodes (LEDs) (e.g., lighting devices, information display panels, LED TVs, etc.) to improve LED brightness. It relates to a device that can be fully utilized and a method of providing the same.

As LEDs of various colors and outputs have been recently developed, a large number of LEDs, including BLU (back-light unit) for TVs, LED lighting and LED display boards, can be utilized by utilizing LED's excellent color reproducibility, low power consumption, high speed switching, and long lifespan. Various devices for operating are being developed. In addition, the size of such a device has also become larger.

As the LED devices become larger, the method of controlling a larger number of LEDs with fewer driving circuits or control pins has a great impact on the economics of the LED circuit devices.

For example, in a LED device including nine (3 × 3) LEDs, when a driving circuit (or control pin) is connected to each LED, at least nine driving circuits (or memories connected thereto) are required. Such a control method is called static control. In the case of the static control, independent ON / OFF is possible, and thus the advantage of being used for video playback is expensive.

Another control method of the LED device is a duty (duty) control, which will be described with reference to FIG.

Figure 1 shows a schematic configuration of an LED device using a conventional duty control method, Figure 1 shows a case of 1/3 duty control. As shown in FIG. 1, the 1 / N duty control may turn on / off a specific LED by selecting a specific column (or row) again while selecting a specific row (or column) including N LEDs. At this time, the row selection may be performed by having the driver driving the selected row have a logic level 'high' value, and the selection of a specific column may be performed by the first switching unit (eg, the switch corresponding to the selected column). It can be performed by controlling S1 to S3).

This type of duty control is often used to implement low cost, economical products such as sign boards. The disadvantage of this type of system is that it is not possible to control all LEDs (eg 9) at the same time. have. However, by controlling the LEDs quickly, it is possible to make all the LEDs appear to be on.

2 is a graph showing changes in current and voltage applied to LEDs according to a driving method of a conventional LED device.

In FIG. 2, the solid line represents a change in voltage applied to any one LED included in the conventional LED device as illustrated in FIG. 1, and the dotted line represents a change in current flowing through the one LED.

As can be seen with reference to Figure 2, the LED is kept on (ON) during T _ON and discharged during the next T _off to the OFF (OFF), by performing this more than 100 times per second to make the LED appear to be ON Can be. However, the brightness of the LED is proportional to the current value, and in the duty-based control, there is an inevitable time to turn off the LED as shown in FIG. 2, and this principle may cause a problem that the LED brightness cannot be fully utilized. Can be.

As a result, in various duty control schemes (e.g., duty control schemes such as 1/2, 1/4, 1/8, 1/16, etc.), the smaller the duty, the lower the number of control terminals and the lower the price. Since there is a problem that the brightness of the LED is relatively low.

Accordingly, the technical problem to be achieved by the present invention is to have a charging function for each LED so that even if the duty cycle of driving the LED is lowered, the ON state is maintained for a predetermined time through a simple charging circuit connected to the LED. To provide an LED device having a charging function that can increase the ON time of the LED, and a method of providing the same.

In addition, since the voltage is applied through the charging circuit and the current flows even when the LED is turned off, it is important to select the driving period of the LED device, that is, one row (or column). An LED device having a charging function and a method thereof are provided.

In addition, the present invention provides an apparatus and a method for measuring and selecting such an efficient driving cycle so that the LED included in the LED device can always maintain a constant brightness or more.

In addition, a device capable of correcting the brightness or current characteristics of each of the LEDs included in the LED device by correcting the LED brightness or current characteristics that may be caused by the process error of the LED, resistance, or capacitor included in the LED device; To provide a way.

The LED device having a charging function for achieving the technical problem is connected to a plurality of LED (Light Emitting Diode), a driving unit for driving the plurality of LEDs, and each of the plurality of LEDs in parallel, the plurality of LEDs It includes a plurality of charging circuit for charging any one of the LED is turned on (turn-on) and flowing a current to the LED when the LED is turned off (turn-off).

The LED device having the charging function may include a first resistor connected to the LED in series and connected to the charging circuit in parallel to turn on the LED at a predetermined current value.

The plurality of LEDs may be arranged at N × N and driven at a 1 / N duty.

The LED device having the charging function may further include a first switching unit including N switches for selectively driving N rows.

The LED device having the charging function may further include a controller configured to output a control signal for selectively driving the plurality of LEDs to the driver.

The LED device having the charging function may further include a detector configured to detect a current when at least one LED included in any one row selected from the N rows is turned off, and output the current to the controller.

The LED device having the charging function may further include a second switching unit for selectively connecting the detection unit and the N rows.

The controller measures a first reference ratio duration for each of the at least one first LED based on a signal received from the detector while turning on and off at least one first LED selected from the plurality of LEDs, respectively. The reference driving period of the plurality of LEDs may be determined based on the measured first reference ratio duration.

The first reference ratio duration is a time until a current flows through the first LED by a predetermined ratio compared to the current when the first LED is turned on, or the voltage applied to the second resistor when the first LED is turned on. It may be characterized by a time until a certain ratio of voltage is applied.

The controller measures a second reference ratio duration for each of at least one second LED selected from the plurality of LEDs based on the signal received from the detector, and measures the measured second reference ratio duration and the reference. The control signal for each of the at least one second LED may be corrected based on a driving period.

The control unit stores a correction table for storing information on a correction value for correcting the control signal for each of the at least one second LED, wherein the correction value is determined by the second reference ratio duration and the reference driving period. It can be determined based on the ratio.

LED device having a charging function for solving the technical problem outputs a plurality of light emitting diodes (LED), a driving unit for driving the plurality of LEDs, a control signal for selectively driving the plurality of LEDs to the driving unit And a detector configured to measure a current value flowing through the LED selected by the controller, wherein the controller is configured to receive at least one first LED selected from among the plurality of LEDs while turning them on and off. The first reference ratio duration for each of the at least one first LED may be measured based on the received signal, and the reference driving period of the plurality of LEDs may be determined based on the measured first reference ratio duration.

The controller measures a second reference ratio duration for each of at least one second LED selected from the plurality of LEDs based on the signal received from the detector, and measures the measured second reference ratio duration and the reference. The control signal for each of the at least one second LED may be corrected based on a driving period.

LED device having a charging function for solving the technical problem outputs a plurality of light emitting diodes (LED), a driving unit for driving the plurality of LEDs, a control signal for selectively driving the plurality of LEDs to the driving unit And a detector for measuring a current value flowing through the LED selected by the controller, wherein the controller is configured to turn on at least one of the plurality of LEDs based on a signal received from the detector. The at least one LED may be turned on again when a current flows at a predetermined ratio rather than a current flowing on.

In a method of providing an LED device having a charging function comprising a plurality of LEDs and a driving unit for driving the plurality of LEDs for solving the technical problem, the LED device having a charging function to the reference driving period of the plurality of LEDs Determining, measuring a reference ratio duration of each of the selected at least one second LEDs of the plurality of LEDs, and each of the at least one LED based on the measured reference ratio duration and the reference drive period Compensating the control signal for the output to the drive unit.

The determining of the reference driving period of the plurality of LEDs may include turning on and turning off at least one first LED selected from the plurality of LEDs, respectively, and determining a first reference ratio duration for each of the at least one first LEDs. Determining a reference driving period of the plurality of LEDs based on the measuring and the measured first reference ratio duration.

The LED device having the charging function is connected in parallel to each of the plurality of LEDs, and is charged when any one of the plurality of LEDs is turned on and flows current through the LEDs when the LEDs are turned off. A plurality of charging circuits (capacitor) may be included.

The LED device having a charging function and a method of providing the same according to the present invention have a charging function by connecting a charging circuit to each LED, thereby providing a charging function through a simple charging circuit connected to the LED even if the duty cycle of driving the LED is low. By maintaining the time ON state, there is an effect that can increase the ON time of the LED. Therefore, there is an effect that can make the brightness of the LED even brighter while using less driving circuit or (control pin).

In addition, by measuring the time that a certain ratio of current flows after the LED is turned off by selecting a drive cycle based on this, there is an effect that can be driven so that all the LEDs can maintain more than a certain brightness on average.

In addition, the brightness characteristics, which may be caused by the process error of each LED, resistor, or capacitor included in the LED device, may be corrected for each LED, and thus, accurate color may be expressed.

In addition, the LED device having a charging function and a method of providing the same according to an embodiment of the present invention can be easily produced by a slight modification to the existing low-cost LED driving circuit, the advantage that does not require expensive components There is this.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the drawings cited in the detailed description of the invention, a brief description of each drawing is provided.
1 shows a schematic configuration of an LED device using a conventional duty control scheme.
2 is a graph showing changes in current and voltage applied to LEDs according to a driving method of a conventional LED device.
3 is a view showing any one LED included in the LED device having a charging function and a charging circuit connected thereto according to an embodiment of the present invention.
4 is a graph showing a change in current and voltage applied to any one LED by the LED device having a charging function according to an embodiment of the present invention.
5 is a view showing a schematic configuration of an LED device having a charging function according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating a schematic configuration when an LED device having a charging function according to an embodiment of the present invention has a driving cycle determination function and / or a brightness correction function.
7 is a view for explaining a method for determining a driving cycle in the LED device having a charging function according to an embodiment of the present invention.
8 is a view for explaining a method of performing a brightness correction for each LED of the LED device having a charging function according to an embodiment of the present invention.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings.

Also, in this specification, when any one element 'transmits' data to another element, the element may transmit the data directly to the other element, or may be transmitted through at least one other element And may transmit the data to the other component.

Conversely, when one element 'directly transmits' data to another element, it means that the data is transmitted to the other element without passing through another element in the element.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

3 is a view showing any one LED included in the LED device having a charging function and a charging circuit connected thereto according to an embodiment of the present invention.

Referring to FIG. 3, the LED device 100 having a charging function according to an embodiment of the present invention includes a predetermined LED 111. The LED 111 may be driven by an LED driver 120. The driver 120 may drive the LED 111 by applying a predetermined driving voltage (eg, 3.3V) to the LED 111. Therefore, the driving unit 120 may drive the LED 111 by using a voltage drive method, thereby easily and inexpensively driving the LED 111 compared to driving the LED 111 through a constant current. I can drive it.

A predetermined charging circuit 131 may be connected to the LED 111 in parallel. The charging circuit 131 may be implemented as a capacitor, but is not limited thereto and may be implemented as various circuits that perform the same function.

When the driving unit 120 applies a forward bias to the LED 111, the LED 111 may be turned on while a predetermined current flows in the LED 111. Then, the charging circuit 131 may be charged while the LED 111 is turned on. After that, when the LED 111 is turned off, an electric current flows in the LED 111 as the charge charged in the charging circuit 131 is discharged, thereby substantially increasing the time that the LED 111 is turned on. Can be obtained. The driving unit 120 has a logic level 'high (high) so that the LED 111 is connected to the charging circuit 131 so that the charges charged in the charging circuit 131 can easily flow to the LED 111. ',' 'Low', as well as 'high impedance' can be output as an output value.

On the other hand, the effect that can increase the on time of the LED 111 is shown in FIG.

4 is a graph showing a change in current and voltage applied to any one LED by the LED device having a charging function according to an embodiment of the present invention. In FIG. 4, the solid line is a voltage applied to one of the LEDs 111 included in the LED device 100 having the charging function according to the embodiment of the present invention as shown in FIG. 3, that is, the voltage applied to the node 10. The change in v1 is shown, and the dotted line indicates the change in current i1 flowing through the LED 111.

3 and 4, the LED 111 is maintained in an ON state during T _ON and the charging circuit 131 may also be charged. Thereafter, when the output of the driving unit 120 becomes a high impedance state, the LED 111 is turned off, and the charge charged in the charging circuit 131 is discharged during T2. As can be seen by comparing FIG. 2 with FIG. 4, since the charge charged in the charging circuit 131 flows through the LED 111, T _off in FIG. 2. It can be seen that the current flowing through the LED 111 gradually changes during the T2 time in FIG. 4 compared to the change of the current flowing through the LED during the time. Therefore, even during the T2 time, the LED 111 may have the same effect as being turned on. The T2 time may be dominantly influenced by the resistance component of the LED 111 and the charging capacity (eg, C value) of the charging circuit 131.

Referring back to FIG. 3, the LED device 100 having the charging function may further include a first resistor 141 connected in series with the LED 111 and connected in parallel with the charging circuit 131. .

One end of the first resistor 141 may be connected to one end of the LED 111, and the other end of the first resistor 141 may be connected to a predetermined node 20 commonly connected to one end of the charging circuit 131. Can be. In the LED device 100 having the charging function according to an embodiment of the present invention, since the driving unit 120 uses a voltage driving method, a constant current driver is used to provide a constant current for driving the LEDs 111. Rather than inexpensively, the LED 111 may be provided with a desired current. Therefore, when the driver 120 uses a voltage drive, the first resistor 141 may be required to flow a desired current through the LED 111. Meanwhile, according to another embodiment of the present invention, the first resistor 141 may be connected between the node 20 and the ground in order to flow a desired current value through the LED 111. Therefore, the value of the current flowing through the LED 111 may be adjusted by adjusting the resistance value of the first resistor 141.

Meanwhile, when the first resistor 141 is connected to the LED 111 in series and connected to the charging circuit 131 in parallel as shown in FIG. 3, that is, T2 time as shown in FIG. 4. In fact, even when the LED 111 is off, there is an effect of adjusting the time (hereinafter, 'increase time') to obtain the same effect as on. That is, the T2 time may be dominantly determined by the charging capacity (eg, C value) of the charging circuit 131, the resistance component of the LED 111, and the resistance value of the first resistor 141. Therefore, when fixing the characteristics of the LED 111 and the charging circuit 131, there is an effect that the increase time (T2) can be adjusted by appropriately selecting the resistance value of the first resistor (141).

5 is a view showing a schematic configuration of an LED device having a charging function according to an embodiment of the present invention.

Referring to FIG. 5, the LED device 100 having a charging function according to an embodiment of the present invention includes a plurality of LEDs 111 to 119 and a driver 120 for driving the plurality of LEDs 111 to 119. ) And a plurality of charging circuits 131 ˜ 139 corresponding to each of the plurality of LEDs 111 ˜ 119. In addition, the LED device 100 having the charging function may flow a current of a size required for the plurality of LEDs 111 to 119, and an increase time T2 of each of the plurality of LEDs 111 to 119. It may further include a first resistor unit (141 ~ 149) for adjusting. In addition, the LED device 100 having the charging function may further include a first switching unit 150 for selecting the plurality of LEDs 111 to 119 in units of columns. The first switching unit 150 may include as many switches 151 to 153 as the number of columns formed by the plurality of LEDs 111 to 119.

The LED device 100 having the charging function may duty-control the plurality of LEDs 111 to 119 with a 1 / N duty cycle, and the plurality of LEDs 111 to 119 may have an N × N matrix. It may be arranged in the form. Of course, it may be arranged in another form, the plurality of LEDs (111 ~ 119) may be arranged in any form that can be controlled by a duty control method having a predetermined duty cycle. 5 illustrates a case where 3 × 3 LEDs are included for convenience of description.

The driver 120 may select a row formed by the plurality of LEDs 111 to 119 and apply a predetermined output value V1 to V3 to the LEDs belonging to the selected row. The output value may be output to the plurality of LEDs 111 to 119 through N output terminals (not shown) included in the driving unit 120. The output value output by the output terminal may have 'high', 'low', and 'high impedance' values as described above. The driver 120 may include a plurality of buffers or a transistor transistor logic (TTL).

Each of the plurality of charging circuits 131 to 139 may be connected to an output terminal of the driving unit 120, and may be connected to each of the plurality of LEDs 111 to 119 in parallel. Therefore, when a predetermined LED (eg, 111) is turned on, the charging circuit 131 corresponding to the LED 111 may be charged. In addition, as described with reference to FIG. 3, when each of the plurality of LEDs 111 to 119 is turned on and then turned off, a predetermined increase time is discharged while the charges charged in the corresponding charging circuits 131 to 139 are discharged. The turn on time may be increased during the period T2.

As described above, each of the resistors included in the first resistor units 141 to 149 is connected to each of the plurality of LEDs 111 to 119 in series, and is connected to each of the charging circuits 131 to 139. May be connected in parallel. Each of the first resistor parts 141 to 149 may flow a current having a magnitude required for each of the plurality of LEDs 111 to 119, and the plurality of LEDs may be provided according to the spirit of the present invention. It may also function to adjust each increase time (T2) (111 ~ 119).

The first switching unit 150 may select N columns of the plurality of LEDs 111 to 119. To this end, the first switching unit 150 may include N switches (for example, 151 to 153). For example, when the switch 151 is turned on, at least one of the LEDs 111, 112, and 113 connected to the switch 151 may be turned on. Each of the switches 151 to 153 may be controlled by a predetermined switch signal, and the switch signal may be output by a controller as described below. The switches 151 to 153 may be implemented with a predetermined transistor.

On the other hand, the LED device 100 having a charging function according to an embodiment of the present invention can determine the average driving period, that is, the reference driving period of the plurality of LEDs (111 ~ 119), and each LED ( 111 to 119) may be performed. A schematic configuration for this is shown in FIG. 6.

FIG. 6 is a diagram illustrating a schematic configuration when an LED device having a charging function according to an embodiment of the present invention has a driving cycle determination function and / or a brightness correction function.

Referring to FIG. 6, the LED device 100 having a charging function according to an exemplary embodiment of the present invention may include the controller 160, the detector 170, and / or the second switching unit 180 in the configuration described with reference to FIG. 5. It may further include. In addition, the LED device 100 having the charging function may further include a predetermined memory 190.

The controller 160 may output control signals C1, C2, and C3 for selectively driving the plurality of LEDs 111 to 119 to the driver 120. Based on the control signals C1, C2, and C3, the driver 120 outputs and outputs the output values V1, V2, and V3 of a predetermined LED (eg, 111) among the plurality of LEDs 111 ˜ 119. You can adjust the time. In addition, the controller 160 may output predetermined switch signals S1, S2, and S3 to the first switching unit 150. Then, the first switching unit 150 selectively turns on the switches 151 to 153 included in the first switching unit 150 based on the received switch signals S1, S2, and S3. You can turn it on / off. In addition, the controller 160 may output predetermined switch signals S4, S5, and S6 to the second switching unit 180.

The controller 160 may be implemented as a predetermined micro controller unit (MCU). In addition, the control unit 160 includes a predetermined pulse width modulation (PWM) generator or controls a PWM generator (not shown) provided separately from the control unit 160 to control the control signals C1, C2, and C3. And / or the switch signals S1, S2, and S3 may be generated and output to the driving unit 120 and the first switching unit 150, respectively. In addition, the controller 160 may maintain a predetermined correction table 161. The controller 160 may correct the brightness of at least one of the plurality of LEDs 111 to 119 using the correction table 161.

The detector 170 may detect a current flowing in each of the N rows. In this case, the current detected by the detection unit 170 may be a current when at least one LED included in the N rows is turned off, that is, a current applied by a charging circuit corresponding to the LED. For example, after any one of the LEDs 111 is turned on by the controller 160, the LEDs 111 may be controlled to be turned off. Then, the controller 160 may output a predetermined switch signal S4 such that the switch 181 of the second switching unit 180 is turned on. Then, the predetermined node 30 of the first row including the LED 111 and the detector 170 may be connected by the switch 181. Then, the detector 170 may detect a current flowing in the node 30, that is, a current flowing in the first row. Preferably, the detection unit 170 may turn on only one of the LEDs 111, 114, and 117 included in the first row, and detect a current at turn-off while turning it off. Similarly, each of the switch 182 and the switch 183 included in the second switching unit 180 connects the predetermined node 31, the node 32, and the detector 170 in the second and third rows. Each can be connected.

As a result, the detector 170 may selectively detect the current flowing through the node 30, the node 31, or the node 32. The current flowing through the node 30, the node 31, or the node 32 may be a case in which any one LED included in each row is turned on or turned off. In addition, when turned off, the driving unit 120 may output a 'high impedance' in a row corresponding to each of the nodes 30, 31, and 32.

The intensity of the detected current may be output to the controller 160. When the detector 170 is implemented as an analog to digital converter (ADC), the detector 170 may output a digital value corresponding to the detected intensity of the current to the controller 160. The technical idea of determining a reference driving period of the LED device 100 having the charging function or correcting the brightness of each LED according to the value measured by the detector 170 will be described later.

The memory 190 may store information on an input value for driving each of the plurality of LEDs 111 to 119. For example, when the LED device 100 having the charging function is a device capable of realizing 24-bit true color by using 8 bits of each RGB value, the memory 190 includes the plurality of LEDs 111 ˜. 119) may include information on each input value. For example, when the LED 111 is a diode emitting a predetermined color (eg, R), the memory 190 has 256 input values (0 to 255) for adjusting the brightness of the LED 111. May have The controller 160 may adjust the brightness of the LED 111 by adjusting the turn-on time of the LED 111 according to an input value stored in the memory 190. For example, when the input value is '0', the LED 111 may not be turned on, and when the input value is '255', the LED 111 may be controlled to be turned on for the longest time. Accordingly, the controller 160 may generate and output the control signals C1, C2, and C3 to the driver 120 based on an input value stored in the memory 190. The memory 190 may be, for example, a video memory.

As a result, the controller 160 may determine the driving cycle of the LED device 100 having the charging function based on the signal measured by the detector 170, that is, the current intensity value or the voltage value. This will be described with reference to 7.

7 is a view for explaining a method for determining a driving cycle in the LED device having a charging function according to an embodiment of the present invention.

First, referring to FIG. 7A, the controller 160 may select and turn on only one LED (eg, 111) selected from the plurality of LEDs 111 ˜ 119. In this case, the change of the current flowing through the LED (eg, 111) may be measured by the detector 170, and may be as shown in FIG. 7A.

As shown in FIG. 7A, when the LED (eg, 111) is turned on, a current of a predetermined intensity may flow during a time t _on . Thereafter, when the LED (eg, 111) is turned off, the charge that has been charged in the charging circuit 131 corresponding to the LED (eg, 111) flows to the LED (eg, 111), as shown in FIG. 7A. Changes in current can occur. At this time, the controller 160 is a time when the current flowing through the LED (eg, 111) becomes a predetermined ratio (eg, 90%) compared to the current at turn-on, based on the signal received from the detection unit 170, The reference ratio duration (t _on + t _off ) can be measured. The predetermined ratio (eg, 90%) may be higher than a predetermined threshold that may turn on the LED (eg, 111), and the predetermined ratio may have various values depending on implementation.

As such, when the reference ratio duration is measured, the controller 160 controls the driving unit 120 and / or the first switching to be turned on again when the reference ratio duration elapses after the LED (eg, 111) is turned on. The unit 150 may be controlled.

As a result, according to the LED device 100 having a charging function according to an embodiment of the present invention, a predetermined LED (eg, 111) always has a predetermined ratio (eg, 90%) or more of brightness compared to the brightness at turn-on. Can be driven.

On the other hand, the controller 160 is a driving cycle of the plurality of LEDs (111 ~ 119) based on the reference ratio duration of any one of the plurality of LEDs (111 ~ 119) (for example 111) ( For example, although the driving period of the first switching unit 150 may be determined, the driving period of the plurality of LEDs 111 to 119 based on the reference ratio duration of the plurality of LEDs (eg, 111) may be determined. Driving period of the first switching unit 150) may be determined.

For example, the controller 160 may further measure the reference ratio duration of the LED (eg, 114) included in a different column from the LED (eg, 111) which measured the reference ratio duration in FIG. 7A. And the measurement result may be as shown in Figure 7b. As can be seen with reference to FIGS. 7A and 7B, the reference ratio duration measured in FIG. 7B may be shorter. The difference in the reference ratio duration is that device characteristics may vary depending on the manufacturer, process error, etc. of the LED, the charging circuit (eg, the capacitor), and / or the first resistors. In this case, the driving period of the plurality of LEDs 111 to 119 (for example, the driving period of the first switching unit 150) using an average value of the measured reference ratio durations or using a predetermined other representative value. May be determined.

On the other hand, the determined driving period, that is, the reference driving period (for example, the driving period of the first switching unit 150) is suitable for all of the plurality of LEDs 111 to 119 to maintain the brightness of the predetermined ratio (90%). You may not. This may be the process error of each of the elements as described above, even if the reference drive period is the average value of the reference ratio duration measured for a plurality of LEDs or the reference ratio duration for any one LED Because it is determined by.

Therefore, the LED device 100 having a charging function according to an embodiment of the present invention further provides a technical idea of correcting brightness for each LED. This will be described with reference to FIGS. 7 and 8.

8 is a view for explaining a method of performing a brightness correction for each LED of the LED device having a charging function according to an embodiment of the present invention.

7 and 8, for example, the first reference ratio duration as shown in FIG. 7A may be a reference driving period. Then, the controller 160 may drive the plurality of LEDs 111 to 119 according to the reference driving period.

However, as shown in FIG. 7B, the predetermined LED 2 (eg, 114) may have a reference ratio duration shorter than the first reference ratio duration. Therefore, when the LED 2 (eg, 114) is driven at a reference driving period, the brightness of the predetermined ratio (eg, 90%) may not be guaranteed. Thus, some correction may be necessary for the LED 2 (eg, 114).

To this end, the controller 160 may measure a second reference ratio duration for the LED 2 (eg, 114). The predetermined correction value for the predetermined LED 2 (eg, 114) may be determined based on the second reference ratio duration and the reference driving period.

For example, when the second reference ratio duration is 0.9 times compared to the first reference ratio duration, the correction value for the LED 2 (eg, 114) may be 0.9. Then, the controller 160 may store the identification information (eg, (0,0)) and the correction value of the LED 2 (eg, 114) in the correction table 161. As such, the controller 160 may generate and store the correction value for all or part of the plurality of LEDs 111 to 119.

Thereafter, the controller 160 can read an input value (eg, '128') for a predetermined LED 2 (eg, 114) from the memory 190. Then, the controller 160 may output a control signal for controlling the driver 120 to have a turn on time corresponding to the input value (eg, '128'). In this case, the control signal may be a control signal corrected based on the correction value. That is, when the turn-on time corresponding to the input value '128' is t1, the driver 120 receives a control signal corrected such that the LED 2 (eg, 114) has a turn-on time for a time t1 / 0.9. Can be printed as

As a result, the LED device 100 having the charging function according to the embodiment of the present invention automatically determines a predetermined reference driving period so that the plurality of LEDs 111 to 119 can be driven with a predetermined brightness or more on average. Can be controlled. In addition, by performing a predetermined correction on each of the plurality of LEDs (111 ~ 119) may be controlled so that each individual LED can be driven above the predetermined brightness.

The LED device having a charging function according to an embodiment of the present invention may be implemented by various devices such as an electric signboard, an illumination device, a predetermined display device (eg, a TV, etc.).

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (17)

A plurality of light emitting diodes (LEDs);
A driving unit driving the plurality of LEDs; And
Connected in parallel to each of the plurality of LEDs, the LED charges when any one of the plurality of LEDs is turned on and current to the LEDs when the LEDs are turned off A plurality of charging circuits for flowing the;
A controller for outputting a control signal for selectively driving the plurality of LEDs to the driver; And
A detection unit for detecting a current when the at least one LED selected from the plurality of LEDs is turned off and outputting the current to the controller;
The control unit,
Measuring and measuring a first reference ratio duration for each of the at least one first LED based on a signal received from the detector while turning on and turning off at least one first LED selected from the plurality of LEDs, respectively LED device having a charging function to determine the reference driving period of the plurality of LEDs based on the first reference ratio duration.
According to claim 1, The LED device having a charging function,
And a first resistor connected in series to the LED and connected in parallel to the charging circuit to turn on the LED at a predetermined current value.
The method of claim 1, wherein the plurality of LEDs,
The LED device having a charging function, characterized in that arranged in N × N is driven by 1 / N duty (duty).
According to claim 3, The LED device having a charging function,
An LED device having a charging function further comprising a first switching unit including N switches for selectively driving N rows.
delete delete According to claim 4, The LED device having a charging function,
And a second switching unit for selectively connecting the detection unit and the N rows.
delete The method of claim 1, wherein the first reference ratio duration is,
The LED device having a charging function, characterized in that the current flowing through the first LED is a time until a current of a predetermined ratio flows compared to the current at the time of turn-on.
The method of claim 1, wherein the control unit,
The second reference ratio duration for each of the at least one second LED selected from the plurality of LEDs is measured based on the signal received from the detector, and the measured second reference ratio duration and the reference driving period are measured. LED device having a charging function for correcting the control signal for each of the at least one second LED based on.
The method of claim 10, wherein the control unit,
A correction table storing information on a correction value for correcting the control signal for each of the at least one second LED,
And the correction value is determined based on a ratio between the second reference ratio duration and the reference driving period.
A plurality of light emitting diodes (LEDs);
A driving unit driving the plurality of LEDs; And
A controller for outputting a control signal for selectively driving the plurality of LEDs to the driver; And
A detection unit for measuring a current value flowing through the LED selected by the control unit,
The control unit,
Measuring and measuring a first reference ratio duration for each of the at least one first LED based on a signal received from the detector while turning on and turning off at least one first LED selected from the plurality of LEDs, respectively LED device having a charging function to determine the reference driving period of the plurality of LEDs based on the first reference ratio duration.
The method of claim 12, wherein the control unit,
The second reference ratio duration for each of the at least one second LED selected from the plurality of LEDs is measured based on the signal received from the detector, and the measured second reference ratio duration and the reference driving period are measured. LED device having a charging function for correcting the control signal for each of the at least one second LED based on.
A plurality of light emitting diodes (LEDs);
A driving unit driving the plurality of LEDs; And
A controller for outputting a control signal for selectively driving the plurality of LEDs to the driver; And
A detection unit for measuring a current value flowing through the LED selected by the control unit,
The control unit,
On the basis of the signal received from the detection unit, the at least one LED of the plurality of LEDs when the current flows at a predetermined ratio compared to the current flowing at the time of turning on the at least one LED is turned on again LED device having a charging function.
In the LED device providing method having a charging function comprising a plurality of LEDs and a driving unit for driving the plurality of LEDs,
Determining, by an LED device having a charging function, a reference driving period of the plurality of LEDs;
Measuring a reference ratio duration of each of the at least one second LED selected from the plurality of LEDs; And
And correcting a control signal for each of the at least one LED based on the measured reference ratio duration and the reference driving period, and outputting the corrected control signal to the driving unit.
The method of claim 15, wherein determining the reference driving period of the plurality of LEDs,
Measuring a first reference ratio duration for each of the at least one first LED while turning on and turning off at least one first LED selected from the plurality of LEDs, respectively; And
Determining a reference driving period of the plurality of LEDs based on the measured first reference ratio duration.
The method of claim 15, wherein the LED device having a charging function,
A plurality of charging circuits connected in parallel to each of the plurality of LEDs and configured to charge when one of the plurality of LEDs is turned on and to flow current to the LEDs when the LEDs are turned off LED device having a charging function including a dog.

Images