KR102131265B1 - Micro Display and Test Method thereof - Google Patents

Abstract

Embodiments of the present invention disclose a micro-display device and its inspection method.
A pixel of a display device according to an exemplary embodiment of the present invention includes a first electrode and a second electrode, and the first electrode is a light emitting element connected to the power line; A pixel circuit connected to the second electrode of the light emitting element; And an inspection transistor connected between the first electrode and the second electrode of the light emitting element and turned on by an inspection control signal to test the defect of the pixel.

Description

Micro display and test method thereof

Embodiments of the present invention relate to a micro display device and an inspection method thereof.

As the information society develops, the demand for a display device for displaying images is increasing, and a liquid crystal display device, a plasma display device, and an organic light emitting display device Various types of display devices, such as, are used.

Recently, interest in a high-resolution display device (hereinafter referred to as "micro display device") using a micro light-emitting diode (μLED) has increased.

Embodiments of the present invention provide a method for easily inspecting a pixel array of a micro display.

A display device according to an exemplary embodiment of the present invention includes: a plurality of pixels arranged in a display area; And a power supply unit provided around the display area and outputting a power voltage to a power line connected to the plurality of pixels.

Each of the plurality of pixels includes a first electrode and a second electrode, and wherein the first electrode is connected to the power line; A pixel circuit connected to the second electrode of the light emitting element; And an inspection transistor connected between the first electrode and the second electrode of the light emitting element and turned on by an inspection control signal to test the defect of the pixel.

The display device may include a test unit provided between the power supply unit and the power line, and measuring a current flowing through the power line while the test transistor is turned on.

An inspection method of a display device including a plurality of pixels according to an exemplary embodiment of the present invention includes: applying an inspection signal to the pixel circuit; Turning on the inspection transistor; Measuring a current flowing in the power line through the inspection transistor; And determining whether the pixel is defective by comparing the measured current with a reference current corresponding to the inspection signal.

Embodiments of the present invention can easily detect information on defective pixels and perform quality verification by inspecting a pixel array of a micro display.

1 is a view schematically showing a manufacturing process of a display device according to an exemplary embodiment of the present invention.
2 is a view schematically showing a display device according to an exemplary embodiment of the present invention.
3 is an example of a pixel of the display device illustrated in FIG. 2.
FIG. 4 is a diagram schematically showing a part of the display device illustrated in FIG. 2.
5 is a timing diagram for describing an inspection mode of the display device illustrated in FIG. 4.
6 is a view schematically showing a display device according to another exemplary embodiment of the present invention.
7 is an example of a pixel of the display device illustrated in FIG. 6.
FIG. 8 is a diagram schematically showing a part of the display device illustrated in FIG. 6.
9 is a timing diagram for describing an inspection mode of the display device illustrated in FIG. 8.

The present invention can be applied to various transformations and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. Effects and features of the present invention and methods for achieving them will be clarified with reference to embodiments described below in detail together with the drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be given the same reference numerals when describing with reference to the drawings, and redundant description thereof will be omitted. .

In the following examples, terms such as first and second are not used in a limiting sense, but for the purpose of distinguishing one component from other components. In addition, in the following embodiments, the singular expression includes a plural expression unless the context clearly indicates otherwise.

In the following embodiments, when X and Y are connected, X and Y are electrically connected, X and Y are functionally connected, and X and Y are directly connected. Can. Here, X, Y may be an object (for example, a device, an element, a circuit, a wiring, an electrode, a terminal, a conductive film, a layer, etc.). Therefore, it is not limited to a predetermined connection relationship, for example, the connection relationship shown in the drawings or detailed description, and may include other than the connection relationship shown in the drawings or detailed description.

When X and Y are electrically connected, for example, an element (eg, switch, transistor, capacitive element, inductor, resistance element, diode, etc.) that enables electrical connection between X and Y, It may include a case where one or more are connected between X and Y.

In the following embodiments, “ON” used in connection with the device state refers to the activated state of the device, and “OFF” refers to the deactivated state of the device. “On” used in connection with a signal received by the device may refer to a signal that activates the device, and “off” may refer to a signal that deactivates the device. The device can be activated by a high voltage or a low voltage. For example, a P-type transistor is activated by a low voltage, and an N-type transistor is activated by a high voltage. Therefore, it should be understood that the "on" voltages for the P-type transistor and the N-type transistor are opposite (low to high) voltage levels.

In the examples below, terms such as include or have are meant to mean that features or components described in the specification exist, and do not preclude the possibility of adding one or more other features or components.

1 is a view schematically showing a manufacturing process of a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the display device 30 according to an exemplary embodiment may include a light emitting element array 10 and a driving circuit board 20. The light emitting element array 10 may be combined with the driving circuit board 20. The display device 30 may be a micro display device.

The light emitting device array 10 may include a plurality of light emitting devices. The light emitting device may be a light emitting diode (LED). The light emitting device may be a light emitting diode (LED) having a size of micro to nano units. At least one light emitting device array 10 can be manufactured by growing a plurality of light emitting diodes on a semiconductor wafer. Therefore, the display device 30 can be manufactured by combining the light emitting element array 10 with the driving circuit board 20 without having to separately transfer the light emitting diodes to the driving circuit board 20.

A pixel circuit corresponding to each of the light emitting diodes on the light emitting element array 10 may be arranged on the driving circuit board 20. The light emitting diode on the light emitting element array 10 and the pixel circuit on the driving circuit board 20 may be electrically connected to form a pixel.

2 is a view schematically showing a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the display device 30A according to an exemplary embodiment may include a pixel unit 110 and a driving unit.

The pixel unit 110 may be disposed in a display area displaying an image. The pixel unit 110 may include a plurality of pixels PX arranged in various patterns such as a predetermined pattern, for example, a matrix type or a zigzag type. The pixel PX emits one color, and for example, one of red, blue, green, and white colors. The pixel PX may emit colors other than red, blue, green, and white.

The pixel PX may include a light emitting device. The light emitting device may be a self light emitting device. For example, the light emitting device may be a light emitting diode (LED). The light emitting device may emit a single peak wavelength or emit a plurality of peak wavelengths.

The pixel PX may further include a pixel circuit connected to the light emitting element. The pixel circuit may include at least one thin film transistor and at least one capacitor. The pixel circuit can be implemented by a semiconductor stacked structure on a substrate.

The pixel unit 110 includes scan lines SL1-SLn for applying a scan signal to the pixels PX, light emission control lines EL1-ELn for applying a light emission control signal to the pixels PX, and pixels PX. ) May include data lines DL1-DLm for applying a data signal. Also, the pixel unit 110 may include inspection control lines CL1-CLn for applying an inspection control signal to the pixels PX.

Each of the scanning lines SL1-SLn and the emission control lines EL1-ELn is connected to the pixels PX arranged in the same row, and each of the day lines DL1-DLm is the pixels PX arranged in the same column. Can be connected to.

The driving unit is provided in a non-display area around the pixel unit 110 and may drive and control the pixel unit 110. The driving unit 120 may include a control unit 121, a scanning driving unit 122, a data driving unit 123, a power supply unit 124, an inspection driving unit 125, and an inspection unit 126. The driving unit may operate according to the driving mode and the inspection mode.

In the driving mode, under the control of the controller 121, the scan driver 122 sequentially applies scan signals to the scan lines SL1-SLn, and the data driver 123 sends data signals to each pixel PX. Can apply. Under the control of the control unit 121, the scan driving unit 122 may sequentially apply the emission control signal to the emission control lines EL1-ELn. The pixels PX emit light with a brightness corresponding to a voltage level or a current level of the data signal received through the data lines DL1-DLm in response to the scan signal received through the scan lines SL1-SLn.

In the inspection mode, under the control of the control unit 121, the scan driver 122 sequentially applies scan signals to the scan lines SL1-SLn, and the data driver 123 sends a scan signal to each pixel PX. Can apply. Under the control of the control unit 121, the scan driving unit 122 may sequentially apply the emission control signal to the emission control lines EL1-ELn. Under the control of the controller 121, the inspection driver 125 may apply an inspection control signal to each pixel PX.

The power supply unit 124 receives external power and/or internal power, converts it to various levels of voltage required for the operation of each component, and converts the corresponding voltage according to a power control signal input from the controller 121 (110).

The power supply unit 124 may generate a first power voltage VDD and apply it to the pixel unit 110. The power supply unit 124 may generate a driving voltage and apply it to the scan driving unit 122, the data driving unit 123, and the inspection driving unit 125.

The inspection unit 126 may measure the current flowing through the power line while the power supply unit 124 applies the first power voltage VDD to the pixel unit 110 in the inspection mode. The inspection unit 126 may be implemented as a current measurement circuit for current measurement. The inspection unit 126 may measure current in units of each row (line) of the pixel unit 110 and compare the measured current value with a reference current value corresponding to the inspection signal. If the difference between the measured current value and the reference current value is greater than or equal to a threshold value, the inspection unit 126 may determine that the pixel circuit of at least one pixel PX of the pixels PX in the corresponding row is defective.

The control unit 121, the scan driving unit 122, the data driving unit 123, the power supply unit 124, and the inspection driving unit 125 are each formed in the form of a separate integrated circuit chip or a single integrated circuit chip, and the pixel unit 110 ) May be mounted directly on the formed substrate, mounted on a flexible printed circuit film, attached to the substrate in the form of a tape carrier package (TCP), or directly formed on the substrate.

3 is an example of a pixel of the display device illustrated in FIG. 2.

In the embodiment of FIG. 3, pixels PX1 in the n-th row and the m-th column will be described as an example for convenience of description. The pixel PX1 is one of a plurality of pixels included in the n-th row, and is connected to the scan line SLn corresponding to the n-th row and the data line DLm corresponding to the m-th column.

The pixel PX1 is connected to a scan line SLn for transmitting a scan signal, a data line DLm for crossing the scan line SLn, and for transmitting a data signal, and a power line VL for transmitting the first power voltage VDD. Can.

The pixel PX1 may include a light emitting diode (LED) and a pixel circuit connected to the light emitting diode (LED). The pixel circuit may include first to third transistors T1 to T3, a capacitor C, and an inspection transistor TT.

The first transistor T1 includes a gate electrode connected to the first electrode of the capacitor C, a first electrode connected to the light emitting diode LED through the third transistor T3, and a second connected to the second power voltage VSS. It may include an electrode. The second power voltage VSS may be a ground voltage GND. The first transistor T1 serves as a driving transistor, and receives a data signal according to the switching operation of the second transistor T2 to supply current to the light emitting diode (LED).

The second transistor T2 may include a gate electrode connected to the scan line SLn, a first electrode connected to the data line DLm, and a second electrode connected to the gate electrode of the first transistor T1. The second transistor T2 is turned on according to the scan signal received through the scan line SLn and serves as a switching transistor that transfers the data signal transferred to the data line DLm to the gate electrode of the first transistor T1. can do.

The third transistor T3 includes a gate electrode connected to the emission control line ELn, a first electrode connected to the second electrode of the light emitting diode LED, and a second electrode connected to the first electrode of the first transistor T1. can do. The third transistor T3 is turned on according to the light emission control signal transmitted through the light emission control line ELn to allow the driving current of the first transistor T1 to flow through the light emitting diode LED. In the embodiment of FIG. 2, the emission control line ELn is connected to the scan driving unit 122 and receives a light emission control signal from the scan driving unit 122. In another embodiment, the light emission control line ELn may be connected to the light emission control driver (not shown) separate from the scan driver 122 to receive a light emission control signal.

The capacitor C may include a first electrode connected to the gate electrode of the first transistor T1, and a second electrode connected to the second power voltage VSS.

The first electrode of the light emitting diode (LED) may receive the first power voltage VDD from the power line VL. The second electrode of the light emitting diode (LED) may be connected to the first electrode of the third transistor T3. The light emitting diode (LED) can display an image by emitting light with luminance corresponding to a data signal. In the inspection mode, the light emitting diode (LED) may not emit light.

The inspection transistor TT may include a gate electrode connected to the inspection control line CLn, a first electrode and a second electrode respectively connected to the first electrode and the second electrode of the light emitting diode (LED). The inspection transistor TT may be turned on in the inspection mode and turned off in the driving mode.

FIG. 4 is a diagram schematically showing a part of the display device illustrated in FIG. 2. 5 is a timing diagram for describing an inspection mode of the display device illustrated in FIG. 4.

4 and 5, each pixel PX1 is electrically connected to the power line VL, and an inspection unit 126 may be provided between the power line VL and the power supply unit 124.

The power line VL may include a first power line VL1 arranged in a row unit and a second power line VL2 crossing the first power lines and connecting the first power lines VL1.

In row units, the scan signals S1 to Sn are sequentially applied to the pixel units 110 through the scan lines SL1 to SLn, and in response to the scan signals S1 to Sn, the inspection signals are data lines DL1 to DLm. Can be applied as Subsequently, the emission control signals E1 to En may be sequentially applied to the pixel units 110 through the emission control lines EL1 to ELn. The test control signal Test may be applied to the pixel unit 110 through the test control lines CL1 to CLn. The test control signal Test may be applied to all the pixels PX of the pixel unit 110 while the scan signals S1 to Sn are sequentially applied to the pixel unit 110 through the scan lines SL1 to SLn. . The test transistor TT is turned on by the test control signal Test, and the test transistor TT, the third transistor T3, and the first transistor T1 from the power line VL connected to the power supply 124 ), current can flow to ground (GND). The current measurement circuit of the inspection unit 126 may measure the current Itest flowing through the power line VL.

The inspection unit 126 compares the current (Itest) measured in units of rows with a reference current corresponding to the test signal, and if the difference between the measured current (Itest) and the reference current is greater than or equal to a threshold, among the pixels (PX) of the corresponding row It may be determined that at least one pixel is defective. The defect of the pixel may be a defect of the pixel circuit.

6 is a view schematically showing a display device according to another exemplary embodiment of the present invention.

Referring to FIG. 6, the display device 30B according to an exemplary embodiment may include a pixel unit 210 and a driver.

The pixel unit 210 may be disposed in a display area displaying an image. The pixel unit 210 may include a plurality of pixels PXs arranged in various patterns such as a predetermined pattern, for example, a matrix type or a zigzag type. The pixel PX emits one color, and for example, one of red, blue, green, and white colors. The pixel PX may emit colors other than red, blue, green, and white.

The pixel PX may include a light emitting device. The light emitting device may be a self light emitting device. For example, the light emitting device may be a light emitting diode (LED). The light emitting device may be a light emitting diode (LED) having a size of micro to nano units. The light emitting device may emit a single peak wavelength or emit a plurality of peak wavelengths.

The pixel PX may further include a pixel circuit connected to the light emitting element. The pixel circuit may include at least one thin film transistor and at least one capacitor. The pixel circuit can be implemented by a semiconductor stacked structure on a substrate.

The pixel unit 210 may include pulse lines PL1-PLn applying a PWM signal to the pixels PX and inspection control lines CL1-CLn applying an inspection control signal to the pixels PX. . Each of the pulse lines PL1-PLn and the inspection control lines CL1-CLn is connected to the pixels PX arranged in the same row.

The driving unit is provided in a non-display area around the pixel unit 210 and may drive and control the pixel unit 210. The driving unit 220 may include a control unit 221, a PWM driving unit 222, a current supply unit 223, a power supply unit 224, an inspection driving unit 225, and an inspection unit 226. The driving unit may operate according to the driving mode and the inspection mode.

In the driving mode, under the control of the control unit 221, the PWM driving unit 222 sequentially applies a PWM signal to the pulse lines PL1-PLn, and the current supply unit 223 applies current Iref to each pixel PX. ). The pixels PX emit light with a brightness corresponding to the PWM signal received through the PWM driver 222.

In the inspection mode, under the control of the control unit 221, the PWM driving unit 222 sequentially applies a PWM signal of a predetermined bit to the pulse lines PL1-PLn, and the current supply unit 223 includes each pixel ( A current Iref can be applied to PX). Under the control of the control unit 221, the inspection driver 225 may apply an inspection control signal to each pixel PX.

The current supply unit 223 may include a plurality of current sources that supply current to each column of the pixel unit 210.

The power supply unit 224 may generate a first power voltage VDD and apply it to the pixel unit 210. The power supply unit 224 may generate a driving voltage and apply it to the PWM driving unit 222 and the inspection driving unit 225.

The inspection unit 226 may measure the current flowing through the power line while the power supply unit 224 applies the first power voltage VDD to the pixel unit 210 in the inspection mode. The inspection unit 226 may be implemented as a current measurement circuit for current measurement. The inspection unit 226 may measure current in units of each row (line) of the pixel unit 210 and compare the measured current value with a reference current value corresponding to the inspection signal. If the difference between the measured current value and the reference current value is greater than or equal to a threshold value, the inspection unit 226 may determine that the pixel circuit of at least one pixel PX of the pixels PX in the corresponding row is defective.

The control unit 221, the PWM driver 222, the current supply unit 223, the power supply unit 224, and the inspection driver 225 are each formed in the form of a separate integrated circuit chip or one integrated circuit chip, and the pixel unit 110 ) May be mounted directly on the formed substrate, mounted on a flexible printed circuit film, attached to the substrate in the form of a tape carrier package (TCP), or directly formed on the substrate.

7 is an example of a pixel of the display device illustrated in FIG. 6.

In the embodiment of FIG. 7, pixels PX2 in the n-th row and the m-th column will be described as an example for convenience of description. The pixel PX2 is one of a plurality of pixels included in the n-th row, and is connected to a pulse line PLn corresponding to the n-th row and a current source line CSLm corresponding to the m-th column.

The pixel PX2 may include a light emitting diode (LED) and a pixel circuit connected to the light emitting diode (LED). The pixel circuit may include a fourth transistor T4 and a test transistor TT.

The fourth transistor T4 may include a gate electrode connected to the pulse line PLn, a first electrode connected to the second electrode of the light emitting diode LED, and a second electrode connected to the current source line CSLm.

The first electrode of the light emitting diode (LED) may receive the first power voltage VDD from the power line VL. The second electrode of the light emitting diode (LED) may be connected to the first electrode of the fourth transistor T4. The light emitting diode (LED) can display an image by emitting light with luminance corresponding to the PWM signal. In the inspection mode, the light emitting diode (LED) may not emit light.

The inspection transistor TT may include a gate electrode connected to the inspection control line CLn, a first electrode and a second electrode respectively connected to the first electrode and the second electrode of the light emitting diode (LED). The inspection transistor TT may be turned on in the inspection mode and turned off in the driving mode.

FIG. 8 is a diagram schematically showing a part of the display device illustrated in FIG. 6. 9 is a timing diagram for describing an inspection mode of the display device illustrated in FIG. 8.

8 and 9, each pixel PX is electrically connected to a power line VL, and an inspection unit 226 may be provided between the power line VL and the power supply unit 224. The inspection unit 226 may be implemented as a current measurement circuit for current measurement.

The power line VL may include a first power line VL1 arranged in a row unit and a second power line VL2 crossing the first power lines and connecting the first power lines VL1.

In units of rows, PWM signals PWM1 to PWMn may be sequentially applied to the pixel units 210 through pulse lines PL1 to PLn. At the same time, the test control signal Test may be applied to the pixel unit 210 through the test control lines CL1 to CLn. The test control signal Test may be applied to all the pixels PX of the pixel unit 110 while the PWM signals PWM1 to PWMn are sequentially applied to the pixel unit 110 through the pulse lines PL1 to PLn. have. The test transistor TT is turned on by the test control signal Test, and the ground (GND) is passed through the test transistor TT and the fourth transistor T4 from the power line VL connected to the power supply 124. ), a current may flow. The current measurement circuit of the inspection unit 226 may measure the current Itest flowing through the power line VL.

The inspection unit 226 compares the current (Itest) measured in units of rows with a reference current corresponding to the test signal, and if the difference between the measured current (Itest) and the reference current is greater than or equal to a threshold, among the pixels (PX) of the corresponding row It may be determined that at least one pixel is defective. The defect of the pixel may be a defect of the pixel circuit.

According to an embodiment of the present invention, a PWM signal for each bit is generated, and pixel defects can be inspected by repeating bit by bit.

In a display device having a small pixel size, such as a micro display device, the number of pixels is large, so inspection through special equipment such as a probe pin is impossible, and defects may occur in the inspection step, resulting in high quality of the display device and loss in subsequent assembly steps. .

An embodiment of the present invention can detect defect pixel information and perform quality verification by adding an inspection element in the pixel and inspecting the characteristics of the pixel circuit through the current consumption of the power stage.

In an embodiment of the present invention, the operation according to the inspection mode may be performed after the light emitting element array 10 is combined with the driving circuit board 20 and before modularization. Therefore, it is possible to block the shipment of a defective product in advance and improve the yield of the display device through repair using the defect detection result.

The present invention has been described with reference to one embodiment shown in the accompanying drawings, but this is only exemplary, and those skilled in the art can recognize that various modifications and other equivalent embodiments are possible therefrom. You will understand. Therefore, the true protection scope of the present invention should be defined only by the appended claims.

Claims (3)

A plurality of pixels arranged in the display area;
A power supply unit provided around the display area and outputting a power voltage to a power line connected to the plurality of pixels; And
Includes; inspection unit provided between the power supply and the power line,
Each of the plurality of pixels,
A light emitting device including a first electrode and a second electrode, wherein the first electrode is connected to the power line;
A pixel circuit connected to the second electrode of the light emitting element; And
And an inspection transistor connected between the first electrode and the second electrode of the light emitting element and turned on by an inspection control signal to test the defect of the pixel.
The inspection transistors of each of the plurality of pixels are connected in units of rows through the power line,
The robust inspection unit is a micro display device that measures the inspection current flowing through the power line while the inspection transistors connected to each row are turned on. delete In the inspection method of a display device including a plurality of pixels,
Each of the plurality of pixels,
A light emitting device including a first electrode and a second electrode, wherein the first electrode is connected to a power line to which a power voltage is applied;
A pixel circuit connected to the second electrode of the light emitting element;
An inspection transistor connected to the first electrode and the second electrode of the light emitting element; And
Includes; inspection unit provided between the power supply and the power line,
The inspection method,
Applying an inspection signal to the pixel circuit;
Turning on the inspection transistor;
Measuring a test current flowing through the power line through each of the test transistors connected in row units through the power line; And
And determining whether the pixel is defective by comparing the test current flowing through the power line and a reference current corresponding to the test signal while the test transistors connected to the row unit are turned on by the test unit. Inspection method of micro display.

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