KR100774994B1 - Temperature compensation type led display apparatus - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED display device, in which LEDs driven by a driving IC are prevented from deteriorating and / or discoloring due to an increase in temperature, in particular, an unnecessary current increase due to an external temperature increase, so that a good display image quality can be continuously maintained. It is to provide an LED display device.

To this end, the LED display device according to the present invention is provided between an LED display module, a drive IC connected to the LED display module, and the drive IC and an external ground, so that the electric power is increased at an increase in temperature including an external temperature. It includes a thermal resistor to increase the resistance to lower the current flowing through the LED display module.

Display, Current, LEDs, Driver ICs, Thermal Resistors, Temperature, Degradation

Description

TEMPERATURE COMPENSATION TYPE LED DISPLAY APPARATUS}

1 is a block diagram schematically showing the structure of an LED (Light Emitting Diode) display device according to an embodiment of the present invention.

Figure 2 is a schematic wiring circuit diagram showing an LED display device according to an embodiment of the present invention.

3 is an electric circuit diagram showing a constant current driving IC used in the embodiment of the present invention.

 <Detailed Description of Main Symbols in Drawings>

10: control unit 30: buffer IC

40: constant current drive IC 41: resistor for current setting

45: thermal register 51: LED display module

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED display device, wherein a temperature rise, in particular, an external temperature rise prevents current from flowing through the LED display module by more than a preset current value, thereby degrading, discoloring, and displaying the LED. The present invention relates to a temperature compensation LED display device capable of preventing deterioration of image quality.

LED display devices for arranging the LEDs in a matrix form and driving the arranged LEDs with a constant voltage driving IC are well known in the art. In such an LED display device, the constant voltage driving IC uses a buffer IC and an inverter IC, operates the LED display device in a dynamic pulse driving manner, and has a separate resistor at each port of the LEDs connected to the data circuit. Adjust the brightness of LED by controlling the voltage (forward voltage, forward voltage) applied to each LED.

Here, the dynamic pulse driving method is a method of lighting by scanning one digit in the same manner as the CRT (cathode ray tube), and the scan circuit is in a state in which each row or each column can be sequentially lighted, and synchronized with the timing to be displayed. The lighting of the light emitting diodes can be determined by the data circuit.

However, since the LED display device having the constant voltage matrix structure has to attach an individual resistor to each port and control the light emission of the LED according to the driving voltage of the LED as the resistance value of the individual resistor, when the LED driving voltages are different from each other, It is difficult to set, and there is a problem that the defective rate is high due to the luminance deviation caused by the LED driving voltage deviation.

In this regard, conventionally, an LED display device for controlling the operation of a matrix array of LEDs using a constant current driving IC has been proposed by the present applicant, which is a light emitting diode display dated October 7, 2005. It is disclosed in Korean Patent Publication No. 2005-97162 published in the name of. The conventional LED display device uses a constant current driving IC to supply a constant constant current to the LED without being influenced by a change in the voltage supplied to the LED, thereby contributing to greatly improving the luminance deviation of the LED.

However, conventional LED display devices have a large current higher than the current value set by the heat generated from the LED itself or the driving IC and / or high external heat when the LED is turned on for a long time or the external temperature becomes excessively high. Still suffers from problems with each LED. This excessively flowing current deteriorates and discolors the LED, which is one cause of deterioration of the display quality of the LED display device.

Accordingly, the technical problem of the present invention is to prevent the LEDs driven by the driving IC from deteriorating and / or discoloring due to an increase in temperature, in particular, an unnecessary current increase due to an external temperature increase, thereby maintaining a good display image quality. It is to provide a display device.

In order to achieve the above technical problem, the present invention is provided between an LED display module, a drive IC connected to the LED display module, and between the drive IC and an external ground, at an increase in temperature including an external temperature. It provides an LED display device including a thermal resistor to increase the electrical resistance to lower the current flowing through the LED display module.

In the LED display device according to the embodiment of the present invention, it is preferable that the driving IC is a constant current driving IC including a current setting resistor between an external ground. The thermal resistor is connected in series or in parallel with the current setting resistor, and the current setting resistor is made of a variable resistance element whose resistance can be changed by a user, and the thermal resistor is made of a PTC element. It is preferable.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

<Example>

1 is a block diagram showing an LED display device according to an embodiment of the present invention.

As shown in FIG. 1, the LED display device according to the present embodiment is driven by a constant current driving IC, and its configuration includes, for example, a control unit 10 (see FIG. 2) made of a microcomputer and a driving driver circuit unit. The driver driver circuit portion is constituted by using the buffer IC 30 and the constant current driver IC 40 as drivers. The driver driver circuit portion uses a constant current driver IC 40 (see FIGS. 2 and 3) to which a current setting resistor 41 is connected as an external resistor R-EXT.

FIG. 2 is a block diagram illustrating the LED display device shown in FIG. 1 in more detail.

Referring to FIG. 2, in this embodiment, a 5 V signal scan signal is output from the controller 10 to the buffer IC 30. Subsequently, the buffer IC 30 receives a 5 V signal scan signal, receives an input power supply (DC 5 V to 12 V), and converts the signal scan signal into an LED matrix source scan signal. S1 to S8). In this case, the data to be implemented according to the scan period is outputted by using the constant current driver IC 40, accordingly, the LED display module 51 is turned on. At this time, the current setting resistor 41 connected to the constant current driver IC 40 is an external resistor, and when a variable resistance element is used, the brightness of the LED can be adjusted.

Instead of using the external resistor, a pulse-width modulation (PWM) may be used. The pulse width modulation method is realized by changing the duty ratio (that is, the ratio of on time and off time) of the pulse into a pulse shape that turns on / off the driving power at a constant cycle. That is, a method of adjusting the ratio of time of the high signal to one period has the same effect as changing the driving voltage, but since the method depends on the pulse width, it is called pulse width modulation.

FIG. 3 is a circuit diagram more specifically illustrating the constant current drive IC 40 shown in FIG. 2. The electric circuit of the constant current driving IC 40 shown in FIG. 3 is just one example for explaining the features of the present invention, and various other modifications or variations are possible.

Referring to FIGS. 2 and 3, the constant current driver IC 40 is an external resistance between the external ground and limits the current so that the user can set the current flowing to the LED of the LED display module 51. It includes a resistor for setting current (RESISTOR) 41. The current setting resistor 41 may be formed of a fixed resistance element or a variable resistance element. In this embodiment, the current setting resistor 41 is installed as a variable resistance element, and OUT 0 to OUT shown in FIG. 3. By controlling each port up to 15, the LED voltage of the LED display module 51 may be adjusted, and thus the brightness of the LEDs may be adjusted.

The constant current driver IC 40 is electrically connected to the thermal resistor 45 separately from the above-described current setting resistor 41. According to an embodiment of the present invention, the thermal resistor 45 is connected in parallel with the current setting resistor 41 between the constant current driver IC 40 and ground. The thermal resistor 45 increases resistance in accordance with the temperature inside and outside the circuit, in particular, the temperature outside the circuit, thereby limiting unnecessary current rise due to an increase in the LED and the circuit temperature. In the present embodiment, the thermal resistor 45 is used in parallel with the current setting resistor 41, but this is one embodiment, and the thermal resistor 45 and the current setting resistor 41 are connected in series. It is also possible to connect.

An increase in the temperature of the LED and / or the circuit causes abnormal current to be supplied to the LED module 51 beyond the current value set by the current setting resistor 41 or the like, thereby deteriorating and discoloring the LED and consequently of the LED display device. It causes display quality deterioration. The thermal resistor 45 raises the resistance by increasing its own temperature to lower the current flowing to the LED, which prevents the above-described degradation and discoloration of the LEDs so that good display quality can be maintained continuously.

As a preferred embodiment of the present invention, the thermal resistor 45 includes a PTC (Positive Temperature Coefficient) element having a good responsiveness to temperature change, that is, sensitive to a current flowing for a short time and increasing its own electrical resistance. It is preferred to be used.

As shown in Fig. 2, the LED display module 51 in this embodiment is composed of an 8x10 matrix arrangement. In the drawing, the number of LEDs is slightly different for each line, and one light emitting diode is installed at each point from the data circuits D1 to D7, two D8s, four D9s, and two D10s. have. The scan circuit is installed from S1 to S8. Therefore, the LED display of 80 points can be realized.

When the LED display module 51 and the constant current driver IC 40 are connected to each other, it is not necessary when the 5 V power source is used, but when the 12 V power source is used, the constant current driver IC 40 generates heat. 42 may be necessary in addition. In addition, a voltage drop occurs in the LED display module 51, and particularly, in a power supply of about 12V, a resistor 43 may be further connected to prevent heat from being transferred to the light emitting diodes. However, the additional installation of the resistors 42, 43 above can be halved by the thermal resistor 42 described above, which is quite economical assuming that the resistors 42, 43 are omitted. It can provide a benefit.

While the invention has been described above with reference to specific embodiments, various modifications, changes or modifications may be made in the art within the spirit and scope of the appended claims, and thus, the foregoing description and drawings It should be construed as illustrating the present invention rather than limiting the technical spirit of the present invention.

According to an embodiment of the present invention, the current applied to the LED display module is preset by the temperature rise of the LEDs constituting the LED display module, the temperature rise of the electric circuit driving the LEDs, in particular, the external temperature rise. It prevents excessive flow beyond the value, which prevents LED deterioration and discoloration caused by the excessive current flow, and can continuously maintain good LED display quality.

Claims (5)

An LED display module; A constant current driver IC coupled to the LED display module; A thermal resistor provided between the constant current driver IC and an external ground, the electrical resistor increasing when a temperature including an external temperature increases to lower a current flowing through the LED display module; A current setting resistor connected between the constant current driver IC and the external ground in series or in parallel with the thermal resistor, the resistor having a variable resistance element capable of varying resistance by a user; Temperature compensated LED display device comprising. delete delete delete The temperature compensating LED display device according to claim 1, wherein the thermal resistor is made of a PTC element.

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