KR20110016206A - Inorganic electroluminescent display - Google Patents

Abstract

PURPOSE: An inorganic electroluminescent display is provided to simplify the configuration of a switch unit by using a switch element having low internal withstanding voltage. CONSTITUTION: A plurality of pixels are defined in a substrate. An inorganic electroluminescence device(101) is formed in each pixel. The inorganic electroluminescence device comprises a first electrode(101a), a light-emitting layer(101c) and a second electrode(101e) An AC input(102) applies AC voltage to the second electrode. A switching unit(103) controls the inorganic electroluminescence device. The switching unit is interposed between the first electrode of the inorganic electroluminescence device and the ground.

Description

Inorganic Electroluminescent Display {INORGANIC ELECTROLUMINESCENT DISPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic electroluminescent display, and in particular, a switching element having a low breakdown voltage can be used in a switching unit for controlling an inorganic electroluminescent element formed in each pixel, and the circuit structure of the switching unit is simple, thereby reducing manufacturing costs. The present invention relates to an inorganic electroluminescent display device.

In today's information society, the role of the electronic display device becomes very important, and various electronic display devices are widely used in the industrial field and life.

These electronic displays are mainly used for televisions and computer monitors, and the cathode ray tube (CRT) display, which has the longest history, has a high market share, but such as heavy weight, large volume and high power consumption. It has a lot of disadvantages.

Therefore, in recent years, due to the rapid development of semiconductor technology, flat panel display devices such as electroluminescent display devices and liquid crystal display devices have been developed as new electronic display devices, and various flat display devices have advantages such as light weight and thinness. It attracts a lot of attention.

Recently, in addition to the above-mentioned advantages such as light weight, thinness, etc., an interest in an electroluminescent display device which is advantageous in terms of power consumption is increasing due to the advantage of not requiring a backlight.

Hereinafter, an inorganic electroluminescent display device will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of an inorganic electroluminescent device provided in a conventional inorganic electroluminescent display, and FIG. 2 illustrates an equivalent circuit of the inorganic electroluminescent device shown in FIG. 1, and FIG. 3 and FIG. An equivalent circuit of a typical inorganic electroluminescent display is shown.

Referring to FIG. 1, a conventional inorganic electroluminescent device 1 includes a transparent electrode 1a, a first insulating layer 1b formed on the transparent electrode 1a, and a first insulating layer 1b. An inorganic electric field formed of a light emitting layer 1c formed on the upper surface, a second insulating layer 1d formed on the light emitting layer 1c, and a back electrode 1e formed on the second insulating layer 1d. AC power of several hundred volts [V] is applied to the back electrode 1e of the light emitting element 1.

Such a conventional inorganic electroluminescent device 1 may be represented by an equivalent circuit, and as shown in FIG. 2, the light emitting layer 1c may be represented by a resistance, and both ends of the first and second insulators may be formed on the light emitting layer 1c. It can be shown that the first and second capacitors due to 1b, 1d) are connected in series.

The inorganic electroluminescent display device in which the inorganic electroluminescent element 1 having the above-described configuration is formed for each pixel has the configuration as shown in FIG.

That is, referring to FIG. 3, a conventional inorganic electroluminescent display includes a substrate in which a plurality of pixels are defined, an inorganic electroluminescent element 1 formed in each pixel on the substrate, and the inorganic electroluminescent element 1. Each of the transparent electrodes 1e is provided with an inverter 2 for applying an alternating voltage to the inorganic electroluminescent element 1.

In the conventional inorganic electroluminescent display device having the above-described configuration, an inverter 2 is required for each pixel, and thus, a size of a circuit for driving the inorganic electroluminescent element 1 has been increased and a manufacturing cost has been increased. As an alternative to solve the same problem, an inorganic electroluminescent display device having a switching circuit unit 24 formed between the AC power supply unit 22 and the inorganic electroluminescent element 21 is designed as shown in FIG. 4.

However, since the conventional inorganic electroluminescent display device as shown in FIG. 4 switches near the AC power supply unit 22 to which high voltage is applied, the switching circuit unit 24 must include a switching device with high breakdown voltage, thereby increasing manufacturing costs. There has been a problem, and since switching is controlled based on a floating node swinging with an alternating current, the circuit configuration of the switching circuit part 24 is complicated, and thus a number of necessary elements have been disadvantageous.

Accordingly, the present invention is to solve the above problems, an object of the present invention is to use a switching element having a low breakdown voltage in the switching unit for controlling the inorganic electroluminescent element formed in each pixel, the circuit configuration of the switching unit is It is to provide an inorganic electroluminescent display device which is simple and reduces manufacturing cost.

In order to achieve the above object, an inorganic electroluminescent display device according to an exemplary embodiment of the present invention includes a substrate on which a plurality of pixels are defined; An inorganic electroluminescent element formed in each pixel on said substrate and comprising at least a first electrode, a light emitting layer on said first electrode, and a second electrode on said light emitting layer; An AC power supply unit applying an AC voltage to a second electrode of the inorganic electroluminescent device; And a switching unit formed between the first electrode of the inorganic electroluminescent device and a ground to control driving of the inorganic electroluminescent device. Characterized in that configured to include.

In addition, a connection point of the first electrode and the switching unit of the inorganic electroluminescent device forms a first node, a connection point of the switching unit and the ground constitutes a second node, and the switching unit includes: an anode connected to the first node; 1 diode; A first switching element having a collector connected to the cathode of the first diode, a control signal input to a base, and an emitter connected to a second node; A second switching element having an emitter connected to the emitter and the second node of the first switching element; A second diode having an anode connected to the collector of the second switching element and a cathode connected to the first node; And an inverter amplifier connected between the base of the first switching element and the base of the second switching element to invert and apply the control signal applied to the base of the first switching element to the base of the second switching element. Characterized in that configured to include.

In the inorganic electroluminescent display device according to the preferred embodiment of the present invention having the above configuration, since the switching unit for controlling the inorganic electroluminescent element formed in each pixel performs a switching function in the vicinity of the ground, the first switching element and the second In the switching device, a switching device having a low breakdown voltage can be employed, thereby minimizing the manufacturing cost.

In the inorganic electroluminescent display device according to the preferred embodiment of the present invention, since the first switching element and the second switching element included in the switching unit are semiconductor devices having a high switching speed, high-speed switching is possible, There is an effect that can increase the response speed of the pixel.

In the inorganic electroluminescent display device according to an exemplary embodiment of the present invention, the on / off duty ratio of the control signal in the switching unit is adjusted to adjust the on / off duty rate of the first switching element and the second switching element. By controlling the on / off time, there is an advantage that the brightness of the light provided by the inorganic electroluminescent device can be adjusted.

Hereinafter, an inorganic electroluminescent display device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 5, an inorganic electroluminescent display device according to an exemplary embodiment of the present invention includes a substrate on which a plurality of pixels are defined; An inorganic material formed in each pixel on the substrate and including at least a first electrode 101a, a light emitting layer 101c on the first electrode 101a, and a second electrode 101e on the light emitting layer 101c Electroluminescent element 101; An AC power supply unit 102 for applying an AC voltage to the second electrode 101e of the inorganic electroluminescent device 101; And a switching unit 103 formed between the first electrode 101a of the inorganic electroluminescent element 101 and a ground to control driving of the inorganic electroluminescent element 101. It is configured to include.

As shown in FIG. 6, a connection point between the first electrode 101a and the switching unit 103 of the inorganic electroluminescent element 101 forms a first node n1, and the switching unit 103 is The connection point of the ground forms a second node n2, and the switching unit 103 comprises: a first diode D1 having an anode connected to the first node n1; A first switching element S1 connected to a collector of the first diode D1, a control signal G1 is input to a base, and an emitter connected to a second node n2; A second switching element S2 having an emitter connected to the emitter of the first switching element S1 and a second node n2; A second diode D2 having an anode connected to the collector of the second switching element S2 and a cathode connected to the first node n1; And a second switching element connected between the base of the first switching element S1 and the base of the second switching element S2 to invert the control signal G1 applied to the base of the first switching element S1. An inverter amplifier amp1 applied to the base of S2; It is configured to include.

Each component of the inorganic electroluminescent display device according to the preferred embodiment of the present invention having such a configuration will be described in detail as follows.

A plurality of pixels are defined on a substrate of the inorganic electroluminescent display device according to a preferred embodiment of the present invention, and an inorganic electroluminescent element 101 is formed in each pixel.

The inorganic electroluminescent element 101 includes a first insulating layer 101b formed on the first electrode 101a, a light emitting layer 101c formed on the first insulating layer 101b, and the light emitting layer 101c. And a second insulating layer 101d formed on the second insulating layer 101d and a second electrode 101e formed on the second insulating layer 101d. In this case, the first electrode 101a is a transparent electrode and the second electrode 101e is a back electrode.

For convenience of description, the inorganic electroluminescent device 101 is shown as an equivalent circuit in FIG. 5, and the light emitting layer 101c is represented by a resistance, and one side of the light emitting layer 101c is disposed between the first insulator 101b. The first capacitor is formed together with the first electrode 101a and the other side forms the second capacitor together with the second electrode 101e with the second insulator 101d interposed therebetween. It is shown to be connected in series with the first capacitor and the second capacitor.

An AC voltage is supplied from the AC power supply unit 102 to the second electrode 101e of the inorganic electroluminescent device having the above-described configuration, and the driving of the inorganic electroluminescent device 101 is controlled between the first electrode 101a and the ground. The switching unit 103 is formed.

The connection point of the first electrode 101a of the inorganic electroluminescent element 101 and the switching unit 103 constitutes the first node n1, and the connection point of the switching unit 103 and the ground is the second node n2. In this way, the switching unit 103 is positioned between the first node n1 and the second node n2, and the switching unit 103 has a configuration as shown in FIG.

Referring to FIG. 6, the switching unit 103 may include: a first diode D1 having an anode connected to the first node n1; A first switching element S1 connected to a collector of the first diode D1, a control signal G1 is input to a base, and an emitter connected to a second node n2; A second switching element S2 having an emitter connected to the emitter of the first switching element S1 and a second node n2; A second diode D2 having an anode connected to the collector of the second switching element S2 and a cathode connected to the first node n1; And a second switching element connected between the base of the first switching element S1 and the base of the second switching element S2 to invert the control signal G1 applied to the base of the first switching element S1. An inverter amplifier amp1 applied to the base of S2; It is configured to include.

In FIG. 6, the first switching device S1 is of npn type and the second switching device S2 is of pnp type. In the following description, the first switching device S1 is npn type. And the second switching element S2 is of the pnp type, but for convenience of description, the first switching element S1 is the pnp type and the second switching element without departing from the gist of the present invention. An example in which (S2) is of npn type may be sufficient.

Although FIG. 6 illustrates that the first switching element S1 and the second switching element S2 are bipolar junction transistors (BJTs), the present invention is not limited thereto, and the present invention is not limited thereto. In the first switching element S1 and the second switching element S2, different types of switching elements may be employed.

When the switching unit 103 is represented by an equivalent circuit, a first output capacitor C1 exists between the collector and the emitter in the first switching device S1, and the second switching device S2 is also already connected to the collector. There is a second output capacitor C2 between the terminals.

In order to turn on the inorganic electroluminescent device 101 by using the switch having the above configuration, an AC voltage of a threshold value or more is applied to the second electrode 101e of the inorganic electroluminescent device 101 and the switching unit 103 is used. ) So that the first electrode 101a of the inorganic electroluminescent element 101 is grounded so that an alternating current is applied to both ends of the inorganic electroluminescent element 101, and the inorganic electroluminescent element 101 is In order to turn off, the switching unit 103 is turned off.

The operation of the switching unit 103 will be described in detail with reference to FIGS. 5 and 6 as follows.

5 illustrates a case in which the AC voltage supplied to the inorganic electroluminescent device 101 has a positive value and a negative value when the switching unit 103 is turned on. A circuit for explaining driving is illustrated, and FIG. 6 illustrates a circuit for explaining a case in which the switching unit 103 is off.

Referring to FIG. 5, the AC voltage supplied to the inorganic electroluminescent device 101 has a positive value and the first switching device S1 is turned on in the first switching device S1. When a control signal G1 greater than the voltage across the base-emitter is applied, current flows from the inorganic electroluminescent element 101 to the ground via the first diode D1 and the first switching element S1.

That is, when the AC voltage has a positive value and the first switching device S1 is turned on, the inorganic electroluminescent device 101, the first diode D1, and the first switching device S1 are used. ), A current path ⓐ to ground is formed, and the inorganic electroluminescent element 101 is turned on.

In addition, an AC voltage supplied to the inorganic electroluminescent device 101 has a negative value, and a base-emitter for turning on the second switching device S2 in the second switching device S2. When a signal smaller than the voltage is applied, current flows from the ground to the inorganic electroluminescent element 101 via the second switching element S2 and the second diode D2. In this case, the control signal G1 applied to the base of the first switching device S1 is inverted through the inverter amplifier amp1 in the second switching device S2, and has the same magnitude as that of the control signal G1. The opposite signal is input.

That is, when the AC voltage has a negative value and the second switching element S2 is on, the ground, the second switching element S2, the second diode D2, and the inorganic electroluminescent element A current path ⓑ to reach 101 is formed, and the inorganic electroluminescent element 101 is turned on.

Referring to FIG. 6, when a control signal G1 having a value of 0 is applied to the first switching element S1, the first and second switching elements S1 and S2 are turned off. The first and second output capacitors C1 and C2 may be equalized between the light emitting device 101 and the ground, but the first and second output capacitors C1 and C2 have a large impedance, and thus an inorganic electroluminescent device. Since the electric current of the degree which can turn ON (101) cannot flow, the inorganic electroluminescent element 101 is turned off.

In the inorganic electroluminescent display device according to the preferred embodiment of the present invention having the configuration as described above, the switching unit 103 for controlling the inorganic electroluminescent element 101 formed in each pixel performs a switching function near the ground. Therefore, in the first switching device S1 and the second switching device S2, a switching device having a low breakdown voltage can be employed, thereby minimizing manufacturing cost.

In addition, since the first switching device S1 and the second switching device S2 of the switching unit 103 are semiconductor devices having a fast switching speed, high-speed switching is possible, and thus the response speed of the pixel defined on the substrate is increased. There is an advantage to increase.

In addition, the switching unit 103 adjusts the on / off duty ratio of the control signal G1 to turn on / off time of the first switching element S1 and the second switching element S2. There is an advantage that it is possible to adjust the brightness of the light provided by the inorganic electroluminescent device 101 by adjusting.

1 is a cross-sectional view showing a conventional general inorganic electroluminescent device.

FIG. 2 is a circuit diagram illustrating the inorganic electroluminescent device of FIG. 1 as an equivalent circuit. FIG.

3 is a circuit diagram illustrating a conventional general inorganic electroluminescent display.

4 is a circuit diagram illustrating another conventional inorganic electroluminescent display.

5 is a circuit diagram illustrating an inorganic electroluminescent display device according to a preferred embodiment of the present invention.

FIG. 6 is a circuit diagram illustrating a configuration of the switching unit of FIG. 5. FIG.

7 and 8 are circuit diagrams for explaining the driving of the switching unit of FIG.

** Description of the symbols for the main parts of the drawings **

101: inorganic electroluminescent element 101a: first electrode

101b: first insulating layer 101c: light emitting layer

101d: second insulating layer 101e: second electrode

102: AC power supply unit 103: switching unit

S1: first switching element S2: second switching element

D1: first diode D2: second diode

amp1: inverter amplifier G1: control signal

C1: first output capacitor C2: second output capacitor

Claims (7)

A substrate in which a plurality of pixels are defined; An inorganic electroluminescent element formed in each pixel on said substrate and comprising at least a first electrode, a light emitting layer on said first electrode, and a second electrode on said light emitting layer; An AC power supply unit applying an AC voltage to a second electrode of the inorganic electroluminescent device; And A switching unit formed between the first electrode of the inorganic electroluminescent device and a ground to control driving of the inorganic electroluminescent device; Inorganic electroluminescent display, characterized in that configured to include. The inorganic electroluminescent display device according to claim 1, wherein the first electrode is a transparent electrode and the second electrode is a back electrode. The method of claim 1, wherein a connection point of the first electrode and the switching unit of the inorganic electroluminescent device forms a first node, and a connection point of the switching unit and the ground constitutes a second node. The switching unit, A first diode having an anode connected to said first node; A first switching element having a collector connected to the cathode of the first diode, a control signal input to a base, and an emitter connected to a second node; A second switching element having an emitter connected to the emitter and the second node of the first switching element; A second diode having an anode connected to the collector of the second switching element and a cathode connected to the first node; And An inverter amplifier connected between the base of the first switching element and the base of the second switching element, inverting and applying the control signal applied to the base of the first switching element to the base of the second switching element; Inorganic electroluminescent display, characterized in that configured to include. 4. The inorganic electroluminescent display device according to claim 3, wherein the first switching element is of npn type and the second switching element is of pnp type. 4. The inorganic electroluminescent display device according to claim 3, wherein the first switching element is pnp type and the second switching element is npn type. 4. The inorganic electroluminescent display of claim 3, wherein each of the first switching element and the second switching element comprises an output capacitor between a collector and an emitter. The inorganic electroluminescent display device according to claim 3, wherein the brightness of the light provided by the inorganic electroluminescent device is adjusted by adjusting an on / off duty ratio of the control signal.

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