Inspection apparatus and inspection method using the same

An inspection method includes: irradiating light through a prism to an inspection object; scanning an inspection region of the inspection object using a photographing unit; receiving, by the photographing unit, reflected light that is reflected from the inspection object; converting the reflected light received by the photographing unit into an intensity of light; and detecting a defect of the inspection object by comparing a thickness of the inspection object corresponding to the intensity of the light with a predetermined thickness of the inspection object. Therefore, the encapsulation layer is inspected before post-processes of cells or the module process, such that the yield and productivity of the OLED device can be improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No. 10-2016-0182746 filed on Dec. 29, 2016, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

Technical Field

The present disclosure relates to an inspection apparatus and an inspection method, and in detail, to an inspection apparatus and an inspection method for inspecting a defect in an encapsulation layer included in an organic light-emitting display apparatus.

Description of the Related Art

As the era of information technology has begun, the field of display that represents electrical information signals graphically has been rapidly growing. In accordance with this, various display devices which are thinner, lighter and consume less power have been developed.

Such display devices include a liquid crystal display (LCD) device, a plasma display panel (PDP) device, a field emission display (FED) device, and an organic light emitting display (OLED) device, etc.

In detail, OLED devices have advantages over other display devices in that they are self-luminous and that they have faster response speed, higher luminous efficiency, brighter luminance and wider viewing angle. Accordingly, OLED devices are attracting attention. In addition, an OLED device capable of emitting white light has been recently developed, such that OLED devices have a wide range of applications such as backlight and illumination. Accordingly, OLED devices are recognized as one of the most important display devices.

SUMMARY

An organic light-emitting display (OLED) device includes an anode, a cathode, and an organic light emitting diode including an emissive layer (EML) disposed between the anode and the cathode. Holes in the anode are injected into the emissive layer, and electrons in the cathode are injected into the emissive layer, such that the electrons and the holes are recombined to form excitons in the emissive layer, and light is emitted therefrom.

In an OLED device including an emissive layer formed of an organic material, the OLED device is encapsulated with glass, metal or film to prevent moisture or oxygen from permeating. By doing so, oxidation of the emissive layer and the electrodes can be prevented, and the OLED device can be protected from mechanical or physical impact externally applied. Therefore, the encapsulation of the OLED device is very important because moisture or oxygen from the outside affects the lifespan or efficiency of the organic light emitting diode.

To encapsulate the organic light emitting diode, a process of forming an encapsulation layer on a mother substrate is performed, where the organic light emitting diode is formed in each of a plurality of cells for forming a plurality of panels. After forming the encapsulation layer on the mother substrate, a scribing process is carried out for cutting the mother substrate into cells.

There is a problem that the encapsulation layer cannot be formed at a desired area due to foreign matters generated during the process of forming the encapsulation layer for sealing the organic light emitting diode. If there is a defect in the encapsulation layer, a crack is created when a flexible OLED device is bent. As a result, moisture or oxygen permeates into the organic light emitting diode, such that the efficiency or the lifespan of the organic light emitting diode is deteriorated. Since the encapsulation layer is inspected during a lighting test performed after the mother substrate has been cut, there is a problem in that the yield of the OLED devices is lowered.

As mentioned above, the encapsulation layer protects the OLED device, and thus it is important to keep or maintain the encapsulation layer from being damaged. Therefore, it is important to keep or maintain the encapsulation layer from being damaged not only in the process of forming it but also in the subsequent processes.

In view of the above, the inventors of the disclosure have invented an inspection apparatus that can inspect defects in an encapsulation after forming it, and an inspection method using the same.

An aspect of the present disclosure is to provide an inspection method and an inspection apparatus capable of inspecting the whole substrate including the encapsulation layer and inspecting defects in the encapsulation layer in real-time.

And, another aspect of the present disclosure is to provide an inspection apparatus and an inspection method capable of inspecting the whole substrate without increasing the processing time.

It should be noted that objects of the present disclosure are not limited to the above-described objects, and other objects of the present disclosure will be apparent to those skilled in the art from the following descriptions.

According to an aspect of the present disclosure, there is provided an inspection method, comprising: irradiating light through a prism to an inspection object; scanning an inspection region of the inspection object using a photographing unit; receiving, by the photographing unit, reflected light that is reflected from the inspection object; converting the reflected light received by the photographing unit into an intensity of light; and detecting a defect of the inspection object by comparing a thickness of the inspection object corresponding to the intensity of the light with a predetermined thickness of the inspection object.

According to another aspect of the present disclosure, there is provided an inspection apparatus comprising: an optical inspection unit including a prism configured to separate light emitted from a light source into spectra; a mirror configured to reflect the separated light toward an inspection object; a photographing unit configured to receive a reflected light that is reflected from the inspection object and to convert the reflected light into an intensity of light; and a detection unit configured to detect a defect of the inspection object by comparing a thickness of the inspection object corresponding to the intensity of the light with a predetermined thickness of the inspection object.

The embodiments of the present disclosure will be described in the detail description with reference to the accompanying drawings.

According to an embodiment of the present disclosure, it is possible to easily detect a defect reflected by variations in the thickness of an encapsulation layer by detecting a defect in the encapsulation layer with a thickness in accordance with the intensity of the light.

According to an embodiment of the present disclosure, it is possible to detect a defect in an encapsulation layer based on the thickness of the encapsulation layer according to the intensity of the light, such that a defect in the encapsulation layer formed of a transparent film can be quantified.

And, according to an embodiment of the present disclosure, the yield and productivity of OLED device can be improved by inspecting the encapsulation layer before post-processes of cells or the module process.

And, according to an embodiment of the present disclosure, the inspection apparatus may further include a line scan camera that includes a photographing unit, such that the entire substrate including the encapsulation layer can be scanned and a defect in the encapsulation layer can be detected.

According to an embodiment of the present disclosure, the step of detecting defects in the inspection object can be performed while scanning a new inspection region, so that the inspection time can be shortened.

And, according to an embodiment of the present disclosure, the inspection apparatus can inspect the entire substrate without increasing the processing time.

It should be noted that effects of the present disclosure are not limited to those described above and other effects of the present disclosure will be apparent to those skilled in the art from the following descriptions.

The Summary is not necessarily to specify essential features of the appended claims, and thus the scope of the claims is not limited thereby.

DETAILED DESCRIPTION

Advantages and features of the embodiment of present disclosure and methods to achieve them will become apparent from the descriptions hereinbelow with reference to the accompanying drawings. However, the present disclosure is not limited to embodiments disclosed herein but may be implemented in various different ways. The embodiments are provided for making the disclosure thorough and for fully conveying the scope of the present disclosure to those skilled in the art. It is to be noted that the scope of the present disclosure is defined only by the claims.

The figures, dimensions, ratios, angles, the numbers of elements given in the drawings are merely illustrative and are not limiting. Like reference numerals denote like elements throughout the descriptions. Further, in describing the present disclosure, descriptions on well-known technologies may be omitted in order not to unnecessarily obscure the gist of the present disclosure. It is to be noticed that the terms “comprising,” “having,” “including” and so on, used in the description and claims, should not be interpreted as being restricted to the means listed thereafter unless specifically stated otherwise. Where an indefinite or definite article is used when referring to a singular noun, e.g., “a,” “an,” “the,” this includes a plural of that noun unless specifically stated otherwise.

In describing elements, they are interpreted as including error margins even without including explicit statements to that effect.

In describing positional relationship, such as “an element A on an element B,” “an element A above an element B,” “an element A below an element B” and “an element A next to an element B,” another element C may be disposed between the elements A and B unless otherwise specified, for example, where the term “directly” or “immediately” is explicitly used.

The terms first, second, third and the like in the descriptions and in the claims are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. These terms are used to merely distinguish one element from another. Accordingly, as used herein, a first element may be a second element within the technical idea of the present disclosure.

Features of various embodiments of the present disclosure may be combined partially or totally. As will be clearly appreciated by those skilled in the art, technically various interactions and operations are possible. Various embodiments can be practiced individually or in combination.

Hereinafter, an inspection apparatus and an inspection method using the same according to embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following description, a mother substrate having a plurality of cells to form organic light-emitting panels will be described as an embodiment of an inspection object.

FIG. 1is a view showing a mother substrate according to an embodiment of the present disclosure.

Referring toFIG. 1, a mother substrate100includes a plurality of cells10each corresponding to the respective organic light-emitting panels. That is, the plurality of cells10is cut into individual cells, to form a plurality of organic light-emitting panels or OLED apparatuses. The “mother substrate”100refers to the entire device or apparatus shown inFIG. 1before cutting the plurality of cells10into individual cells, and includes a substrate11, as well as the cells10which are formed on the substrate11.

Although the cells10are shown as having a rectangular shape inFIG. 1, this is merely illustrative. The cells10may have a variety of shapes such as a circular shape. Scribing lines SL for separating the cells10from one another are formed around each of the cells10. The scribing lines SL may be actually drawn on the substrate11or virtual scribing lines SL may be defined by alignment keys or any marks around the cells10.

In the display area of each of the cells10, a pixel driver circuit and an organic light emitting diode are disposed. The pixel driver circuit may include a thin-film transistor (TFT), a capacitor, etc. The organic light emitting diode includes an anode, an organic emissive layer, and a cathode.

Hereinafter, the cells10, and the positions of an encapsulation layer in each of the cells10and scribing lines SL will be described in detail.

FIG. 2is an enlarged view of area A shown inFIG. 1. Area A includes two cells10_L and10_R.

Referring toFIG. 2, the first cell10_L and the second cell10_R are shown with a scribing line SL therebetween. Each of the first cell10_L and the second cell10_R may be referred to as a display area.

In each of the first cell10_L and the second cell10_R, a pixel driving circuit and an organic light emitting diode are formed on the substrate11. In order to protect the pixel driving circuit and the organic light emitting diode, the encapsulation layer20is disposed so as to surround each of the first cell10_L and the second cell10_R. The scribing line SL is defined between the first cell10_L and the second cell10_R. After forming the encapsulation layer20on the substrate11, the substrate11may be diced along the scribing line SL.

FIG. 3is a cross-sectional view taken along line X-Y ofFIG. 2. Descriptions will be made with reference toFIG. 3in conjunction withFIG. 2.

The substrate11is formed of an insulative material to support various components of the OLED device. In addition, the substrate11may be formed of a material having flexibility such as glass or plastic. For example, the flexible material may include polyimide (PI), polyetherimide (PEI), polyethyelene terephthalate (PET), polycarbonate (PC), polymethylmethacrylate (PMMA), polystyrene (PS), styrene-acrylonitrile copolymer (SAN), silicon-acryl resin, etc. In addition, when the organic light emitting diode that is easy to implement in a flexible display device is applied to automotive lighting or automotive display devices, design freedom is increased to allow for a variety of designs in accordance with the structure or the exterior of the automobile.

And, the OLED device according to embodiments of the present disclosure may be applied to a variety of display devices including a TV, a mobile device, a tablet PC, a monitor, a laptop computer, an automotive display device, etc. And, the OLED device may also be applied to a wearable display device, a foldable display device, a rollable display device, a bendable display device, etc. And, if the substrate11is a flexible substrate, the OLED device may be applied to a curved display device, a foldable display device, a rollable display device, a bendable display device, an automotive display device, etc.

A buffer layer12is formed on the substrate11to protect various components of the OLED device from the permeation of moisture (H2O) or oxygen (O2) from the outside of the substrate11. The buffer layer12may be formed of, but is not limited to, silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof.

The buffer layer12may include a first buffer layer and/or a second buffer layer. The first buffer layer may delay diffusion of moisture and/or oxygen permeating into the substrate11, and may be a multi-buffer. The first buffer layer may be formed of a single layer of silicon oxide (SiOx) or silicon nitride (SiNx), or multiple layers of silicon oxide (SiOx) and silicon nitride (SiNx) stacked alternately. Alternatively, the first buffer layer may be formed of multiple layers having silicon nitride (SiNx), silicon oxide (SiOx) and silicon oxynitride (SiOxNx). The second buffer layer can protect the active layer of the thin-film transistor and suppress various kinds of defects. The second buffer layer may be an active-buffer. The second buffer layer may be formed of amorphous silicon (a-Si), etc. The buffer layer12may include both the first buffer layer and the second buffer layer or may include one of the first buffer layer and the second buffer layer. The buffer layer12may be determined depending on the type and material of the substrate11, the type of the thin-film transistor to be applied to the OLED device, etc., and may be omitted in some implementations.

A first insulating layer13is disposed on the buffer layer12. Since the first insulating layer13may be formed on a gate electrode disposed on the buffer layer12, it may also be referred to as a gate insulating film.

A source and drain electrode14is disposed on the first insulating layer13. The source and drain electrode14may be formed of one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu), an alloy of two or more thereof, or a multi-layer thereof. The source and drain electrode14may be used as a connection electrode for transmitting a voltage applied from the outside through a pad unit40to the pixel driving circuit disposed in the cell10. For example, it may be, but is not limited to, a high-potential voltage (VDD), a low-potential voltage (VSS), or a data voltage (Vdata). When the connection electrode is a low-potential voltage line, the source and drain electrode14may be electrically connected to the cathode included in the organic light emitting diode in the non-display area.

The pad40may be, but is not limited to, formed of the same material as the anode17via the same process. The pad40may come in contact with the source and drain electrode14through a contact hole in a second insulating layer15on the source and drain electrode14. A driver-IC, a flexible printed circuit board (FPCB), a chip on plastic (COP), or a chip on film (COF) may be attached to the pad40.

The second insulating layer15is disposed on the source and drain electrode14. The first insulating layer13and the second insulating layer15may be extended from the display area formed in the cell10.

The first insulating layer13and the second insulating layer15may be formed of a single layer of silicon nitride (SiNx), silicon oxide (SiOx), or silicon oxynitride (SiOxNx). Alternatively, the first insulating layer13and the second insulating layer15may be formed of multiple layers of silicon nitride (SiNx), silicon oxide (SiOx) and silicon oxynitride (SiOxNx).

On the second insulating layer15, a planarization layer16is disposed, which planarizes steps created by the thin-film transistor, etc., formed in the cell10. The planarization layer16may be formed of, but is not limited to, one of acrylic resin, epoxy resin, phenol resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene resin, polyphenylene sulfide resin, and benzocyclobutene.

An anode17is disposed on the planarizing layer16. The anode17may be in contact with the source and drain electrode14through a contact hole in the second insulating layer15. The anode17may also be used as a connection electrode for transmitting a voltage applied from the outside through the pad unit40to the inside of the cell10. For example, it may be, but is not limited to, a high-potential voltage (VDD), a low-potential voltage (VSS), or a data voltage (Vdata).

A bank18is disposed on the anode17formed in the cell10. The bank18may be formed of, but is not limited to, polyimide, acryl resin or benzocyclobutene (BCB) resin. And, an organic emissive layer is disposed on the bank18and on the portion of the anode17not covered by the bank18. The cathode is disposed on the organic emissive layer and the bank18.

A spacer may be disposed on the bank18. The spacer can prevent damage to the organic light emitting diode that may occur by a fine metal mask (FMM) used during the process of patterning the organic emissive layer included in the emission unit of the organic light emitting diode.

The bank18is formed on the part of the anode17formed outside the cell10, and the encapsulation layer20is disposed on the bank18so that the cell10is sealed. The encapsulation layer20includes a first encapsulation layer21, a second encapsulation layer22, and a third encapsulation layer23. The encapsulation layer20may be composed of at least two encapsulation layers, and the number of the encapsulation layers20is not limited.

The first encapsulation layer21and the third encapsulation layer23may be formed of an inorganic material. For example, the first encapsulation layer21and the third encapsulation layer23may be formed of, but is not limited to, one or more layers of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiOxNy). And, the first encapsulation layer21and the third encapsulation layer23may be formed by, but is not limited to, chemical vapor deposition (CVD) or atomic layer deposition (ALD).

At least one encapsulation layer formed of an inorganic material may be further disposed on the third encapsulation layer23. For example, the inorganic material may be formed of, but is not limited to, one or more layers of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiOxNy).

The second encapsulation layer22can prevent problems resulting from foreign material or particles that may be generated during the processes. Accordingly, the second encapsulation layer22may be a particle cover layer (PCL). For example, if the third encapsulation layer23formed of an inorganic material is disposed on the surface of the first encapsulation layer21where particles are attached, without the second encapsulation layer22, there may be a gap around the particles since the inorganic material does not have strong adhesive force with the particles on the surface of the first encapsulation layer21. Accordingly, the encapsulation layer20may be peeled off due to this gap. Accordingly, when the first encapsulation layer21is defective due to cracks generated by the foreign matter or the particles, the foreign matter or the particles can be covered by the second encapsulation layer22. That is, the second encapsulation layer22formed of an organic material is disposed between the first encapsulation layer21and the third encapsulation layer23, such that it is possible to prevent the encapsulation layer20from being peeled off by covering the particles and the periphery of the particles.

The second encapsulation layer22may be formed of an organic material and may be formed as a transparent film. For example, the second encapsulation layer22may be formed of, but is not limited to, one of silicon oxycarbide (SiOCz), acrylic resin, and epoxy resin.

The second encapsulation layer22may be formed by, but is not limited to, screen printing or inkjet printing. The inkjet printing is a technique in which droplets of a material are discharged via a nozzle of an inkjet head, and the material is dispensed and coated onto the second encapsulation layer22. By forming the second encapsulation layer22by the inkjet printing, the thickness of the second encapsulation layer22can be reduced compared to that formed by the screen printing. Therefore, when the encapsulating layer is formed by the ink-jet printing, the encapsulating layer becomes thinner, which is advantageous for the implementation of a foldable display device, a bendable display device, or a rollable display device. And, it is easy to control the position of the second encapsulation layer22at the time of forming it, which is advantageous for implementation of a narrow bezel.

When the second encapsulation layer22is formed by the inkjet printing, the material that is used has a viscosity that is similar to that of water, such that it easily flows. Thus, a dam19may be disposed around the cell10to limit the forming region in the second encapsulation layer22. The dam19can suppress the overflow of the second encapsulation layer22. The dam19may have a single structure or a double structure depending on the height by which the second encapsulation layer22is applied and the height of the dam19. The dam19may be formed of the same material as one or more insulating patterns formed in the display area. For example, the dam19may be formed of the same material as the bank18. The dam19may be, but is not limited to, formed as a double layer of the same material as the bank18and the spacer. Although two dams19are shown inFIG. 3, the number of the dams is not limited to two. For example, one or more dams may be formed and is not limited the numbers of the dams.

It is desired to increase the height of the second encapsulation layer22to prevent the foreign matter from being peeled off. However, as the height of the second encapsulation layer22increases, the number of the dam19or the height of the dam19also has to be increased. And, if it fails to adjust the amount of the organic material to applied to form the second encapsulation layer22, the organic material flows over the dam19to invade the scribing line SL, the pad portion40, or the bending area. Accordingly, it is necessary to detect the overflow of the second encapsulation layer22.

And, when the organic light-emitting panel formed by cutting the substrate into the cells10is used for a foldable display device, a bendable display device or a rollable display device, there is a bending area where a part of the organic light-emitting panel is bent or folded. When a defect is created in the encapsulation layer20in the bending area, cracks are generated in the encapsulation layer20in the process of bending or folding a part of the organic light-emitting panel. Defects or cracks in the encapsulation layer20may provide a path via which moisture or oxygen permeates into the organic light-emitting panel.

And, when a plurality of touch electrodes is formed on the encapsulation layer20in order to configure a touch functionality, there arises a problem that a short-circuit is formed between the touch electrodes due to a defect in the encapsulation layer20.

And, when the second encapsulation layer22is formed by the inkjet printing, the first encapsulation layer21may fail to be completely covered by the second encapsulation layer22if a nozzle is clogged or the ink is not sufficiently spread out. In this case, it may be determined that the second encapsulation layer22was not applied or insufficiently applied. Accordingly, it is necessary to detect a defect caused when the second encapsulation layer22formed of a transparent film is not applied or insufficiently applied.

Additionally, defects that may occur when the second encapsulation layer22is formed by the ink-jet printing include, for example, defects due to particles, defective formation of the encapsulation layer due to poor spreading of the ink, defects due to insufficient or excessive application of the second encapsulation layer22caused by increase or decrease in the amount of the ink discharged from a nozzle, defects caused when the second encapsulation layer22is not applied or insufficiently applied due to the clogging of an inkjet, defects caused by variations in the curing conditions for curing the second encapsulation layer22, defects due to the overflow of the second encapsulation layer22, etc. These defects result in irregularities having a variety of shapes including linear or circular shape on the second encapsulation layer22.

Since there is no inspection method or inspection apparatus for detecting the above-described defects in the second encapsulation layer22yet, such defects in the second encapsulation layer were detected after post-processes of cells or a module process, which are processes of inspecting panels after cutting the substrate into the cells. This results in decrease in the yield or productivity of the OLED devices. Moreover, if the second encapsulation layer22is inspected after the module process by human naked eyes, it is difficult to detect a minute defect in the second encapsulation layer22which is a transparent film. In addition, the skill, experience and concentration of the operator affect the inspection results of the OLED device, and thus the inspection results by human naked eyes may not be reliable. Further, since the inspection by human naked eyes is carried out manually, it takes a long time to conduct the inspection of OLED devices, such that the yield or productivity of the OLED devices decreases.

Therefore, in order to improve the efficiency, lifespan, reliability, yield and productivity of the OLED device, it is very important to detect defects in the encapsulation layer20before post-processes of cells or a module process. Further a method for inspecting defects in a transparent film is required, which is difficult to detect by human naked eyes or by typical vision techniques. Under the circumstances, an inspection apparatus and an inspection method capable of detecting defects in the encapsulation layer20and detecting defects in the transparent film before post-processes of cells or a module process will be described with reference toFIGS. 4 to 7.

FIG. 4is a flowchart for illustrating the manufacturing and inspection procedure of an organic light-emitting panel according to one or more embodiments of the present disclosure. The manufacturing process of organic light-emitting panels will be described with reference toFIGS. 1 to 3, and an inspection method according to the manufacturing process of organic light-emitting panels will be described.

In the display area of each of the cells10included in the substrate11, a pixel driver circuit and an organic light emitting diode (ED) are formed. The pixel driver circuit may include a thin-film transistor (TFT), a capacitor, etc. The organic light emitting diode includes an anode, an organic emissive layer, and a cathode. The organic emissive layer may emit red, green or blue light, and may be formed using an organic light emitting material that is a phosphorescent material or fluorescent material. Alternatively, the emissive layer may include quantum dots (QDs).

Then, an encapsulation layer20is formed on the organic light emitting diode to seal the cell10. At this time, the encapsulation layer20may be a single layer or a multilayer formed of two or more layers.

Then, after the encapsulation layer is formed on the organic light emitting diode, it is inspected whether there is a defect in the encapsulation layer. The encapsulation layer may include all of the first encapsulation layer, the second encapsulation layer and the third encapsulation layer. The third encapsulation layer may be omitted.

After the encapsulation layer20is formed, the second encapsulation layer among the encapsulation layer20is inspected to detect whether there is a defect. The second encapsulation layer22is inspected among other layers because the second encapsulation layer22frequently causes a defect due to the thickness difference. However, this is merely illustrative. The first encapsulation layer and the third encapsulation layer may also be inspected.

If it is determined that there is a defect in the encapsulation layer20, the process feedbacks to the process of forming the encapsulation layer20to remove or solve the defect in the encapsulation layer20. Therefore, the inspection is carried out immediately after the encapsulation layer20is formed, such that a feedback signal is sent to the processing equipment used in forming the encapsulation layer20as soon as a defect in the encapsulation layer20is detected. Accordingly, it is possible to solve the defect in the encapsulation layer20to improve the yield. In addition, it is possible to prevent defects that may occur in subsequent panel inspection or visual inspection, thereby reducing the processing cost.

If it is determined that the encapsulation layer20is good after the inspection, a barrier film may be further disposed on the encapsulation layer20. The barrier film may be a polarizing plate having polarizing function. The barrier film may be omitted.

Then, the step of cutting the substrate11is performed. The substrate11is cut along the scribing lines SL into a plurality of organic light-emitting panels. Each of the organic light-emitting panels separated from the substrate11may be a minimum unit capable of working as a display device.

Then, an electric signal is applied to the organic light-emitting panel to perform panel inspection for detecting defective images such as spot or point defects, line defects, etc. If the step of inspecting the encapsulation layer20after the formation of the encapsulation layer20is not performed, a defect is detected in the step of inspecting the organic light-emitting panels. As used herein, the step of forming the encapsulation layer20may be referred to as a pre-process of cells, while the steps of cutting the substrate after forming the encapsulation layer20and inspecting the panels may be referred to as post-processes.

After the panel inspection is completed, the module process is carried out. The module process improves image quality by attaching an optical film, a printed circuit board and a driver-IC to the organic light-emitting panels, and applies an external signal to the organic light-emitting panels to drive respective organic emitting diodes.

After the module process is completed, the organic light-emitting panels are subjected to exterior visual inspection step. The visual inspection is a process of determining whether the components are properly attached during the module process. The visual inspection may include overall image inspect of the organic light-emitting panels and reliability check which may occur after aging. If there is a defect in the encapsulation layer20, the image and reliability defects due to defect or cracks in the encapsulation layer20can be detected in the visual inspection.

Therefore, by detecting a defect in the encapsulation layer20after forming the encapsulation layer20and before the post-processes of cells or before the module process, a feedback signal can be sent in real-time to the processing equipment that forms the encapsulation layer20. Accordingly, it is possible to check out a defect during the panel inspection or the visual inspection to reduce the cost and to improve the yield or productivity.

Next, an inspection apparatus capable of detecting a defect in the encapsulation layer20will be described.

FIG. 5is a view showing an inspection apparatus according to embodiments of the present disclosure.

FIG. 5is an inspection apparatus for inspecting an inspection object for a defect in the encapsulation layer. The mother substrate100shown inFIG. 1will be described as an example of the inspection object.

The inspection apparatus200may include a stage210, an x-axis moving rail211for moving an optical inspection unit240in the x-axis direction, a holder220for holding an inspection object, and a holder moving rail212for moving the holder220in the x-axis direction.

A horizontal structure230for mounting the optical inspection unit240is disposed on the moving rail211. The horizontal structure230may include a y-axis moving rail231by which the optical inspection unit240is movable in the y-axis direction. The horizontal structure230may also be referred to as a gantry. The horizontal structure230can move in the x-axis, the y-axis and the z-axis directions along with the inspection object. A driving unit for moving the horizontal structure230in the x-axis, y-axis and z-axis directions is disposed below the horizontal structure230. For example, the driving unit may be, but is not limited to, a linear motor.

A plurality of optical inspection units240may be used to inspect scan areas of the inspection object part by part, thereby saving the inspection time of the inspection object, i.e., the encapsulation layer. Three or more optical inspection units240may be provided.

In order to suppress the influence by the external environment on the optical inspection unit240during the inspection, a chamber of a nitrogen (N2) atmosphere, which is a glove box, may be installed to accommodate the inspection apparatus200.

The optical inspection unit240can move the inspection object on the x-axis and the y-axis as desired by the y-axis moving rail231and inspect a defect in the encapsulation layer included in the inspection object. The data measured by the optical inspection unit240is transmitted to a detection unit248through an optical cable251connected to the optical inspection unit240. The detection unit248may include an image processor that extracts an image of the subject and compares the thickness of the inspection object received from the optical inspection unit240with a predetermined thickness of the inspection object, and a determiner that determines whether there is a defect based on the difference in the thickness. Further, the detection unit248may include a display unit that displays determination results. The display unit may be, for example, a computer.

In addition, the inspection apparatus200may include an alignment camera mounted on the horizontal structure230so that it senses an alignment mark on an inspection object or a substrate when the inspection object is placed on the holder220, and aligns the optical inspection unit240with the inspection object while moving the holder220in the y-axis direction and a theta (θ) direction. And, a driving unit for moving the holder220in the y-axis direction and the theta (θ) direction is disposed below the holder220. For example, the driving unit may be, but is not limited to, a linear motor.

The inspection apparatus200may include an auto focusing unit mounted on the horizontal structure230so that it can adjust the focus on the inspection object in real-time, which can be changed while the optical inspection unit240moves along with the inspection object, by adjusting the distance to the inspection object.

As described earlier, the encapsulation layer20may be formed of a silicon-based material or a polymer material and may be a transparent film. It is difficult to check the transparent film by human naked eyes, and it is difficult to check the existence of the transparent film even with general inspection apparatus. Therefore, the optical inspection unit240is used for detecting a defect in the transparent film.

FIG. 6is a view showing an optical inspection unit according to embodiments of the present disclosure.FIG. 7is a view for illustrating a method for detecting a defect in an inspection object according to embodiments of the present disclosure. The inspection apparatus and the inspection method will be described in conjunction withFIGS. 1 and 2.

The optical inspection unit240included in the inspection apparatus200includes a light source245, a lens barrel241, and a photographing unit243.

The photographing unit243may be a line scan camera. The line scan camera can scan the area of 50 mm by 1,500 mm at a time and can observe the inspection object250while it moves. Accordingly, it can inspect every cell10along the periphery to check or determine a defect in the inspection object. Therefore, the entire substrate can be inspected by the line scan camera which is the photographing unit243, and thus a defect in the encapsulation layers, i.e., the inspection objects250included in the entire substrate can be inspected. Since it may take a long time to inspect every cell on the mother substrate100, a plurality of optical inspection units240may be used to inspect the inspection objects250on the mother substrate100by dividing them into groups in order to reduce the process time. Therefore, the inspection apparatus according to one or more embodiments of the present disclosure can inspect the entire substrate without increasing the processing time.

The line scan camera, which is the photographing unit243, displays a color image. Therefore, it has an advantage in that it can easily detect defects in case the inspection object250is formed as or includes a transparent film.

The lens barrel241may include at least one lens or a filter. The filter may be a bandpass filter for splitting light from the light source245by wavelengths. The light from the light source245can be divided into lights in different wavelengths by the bandpass filter. For example, the lights in wavelengths corresponding to red, green, blue and infrared rays, respectively, can be produced. And, the at least one lens included in the lens barrel241may be a magnification lens and a condenser lens or a collecting lens for condensing the light, etc. For example, a magnification lens may include a high magnification lens.

The wavelength of the light from the light source245may be a wavelength of visible light to infrared light, and may range from 400 nm to 900 nm. The light source245can increase the range of the wavelength so as to include the visible light and the infrared light and may use infrared rays for the inspection object which is out of range of the visible light, thereby improving the visibility. More than one light source245may be provided. The plurality of light sources may be red, green, blue, and white light sources, respectively.

And, a prism246, a mirror247and a lens242are added to the optical inspection unit240to detect a defect in the encapsulation layer, which is a transparent film. This will be described with reference toFIGS. 1, 2 and 5.

Referring toFIG. 6, the light from the light source245is transmitted to the prism246.

The angle of incidence of the light from the light source245may range from 10 degrees to 90 degrees from the horizontal plane of the inspection object250. The light source245may further include a tilt unit, which is an angle adjusting unit, to adjust the angle of incidence of the light. Alternatively, the angle adjusting unit of the light source245may be used to adjust different reflection angles for different materials of the inspection object250.

The light source245may be disposed on both sides of the lens barrel241. In case that one of the two light sources245is out of order, the other one can be used. Each of the two light sources245includes a tilt unit which is an angle adjusting unit.

The prism246separates light from the light source245into spectra. In this case, the range of the wavelength of light can be increased by the prism246. When a beam splitter is used instead of the prism246, there may arise a problem that a portion of light from the light source245is reflected and the other is transmitted, and thus the amount of incident light on the inspection object250is reduced, such that wavelength range becomes smaller.

The light split by the prism246is reflected by the mirror247. The mirror247may be a half-mirror (or half transparent and half reflecting mirror). The half-mirror exhibits the property of transmitting half of incident light and reflecting half of the incident light. The mirror247may further include a tilt unit, which is an angle adjusting unit, to increase the intensity of light irradiated from the light source245onto the inspection object250.

The light is reflected by the mirror247toward the inspection object250. That is, the light from the light source245passes through the prism246and is reflected by the mirror247toward the inspection object250. The inspection object250is the mother substrate100, and in more detail, it may be the encapsulation layer20formed in each cell10on the mother substrate100.

The light reflected by the inspection object250passes through the lens barrel241and is transmitted to the photographing unit243. The photographing unit243scans the inspection object250and receives the reflected light to convert the reflective light into the intensity of the light.

Referring toFIG. 5, the detection unit248extracts an image of the inspection object250, and compares a predetermined thickness of the inspection object250with the thickness of the inspection object250according to the intensity of the light, thereby detecting if there is a defect in the inspection object250. The detection unit248extracts images of the inspection object250received from the photographing unit243for each of the wavelengths corresponding to red, green and blue. Then, the detection unit248converts the intensity of the light of the inspection object250received from the photographing unit243into the thickness of the inspection object250. If there is a defect in the inspection object250, the intensity of the light becomes larger than the predetermined intensity of the light of the inspection object250, and accordingly there is a difference in thickness of the inspection object250. In this case, the predetermined thickness of the inspection object is obtained by manufacturing at least five samples, acquiring the intensity of light for each of the samples, and then acquiring the thicknesses according to the intensities of the light. The thickness according to the intensity of the light should be available in any area of the inspection object250. In the detection unit248, the thickness in association with the predetermined intensity of the light of the inspection object may be stored.

The lens242may be disposed on or under the mirror247. The lenses242disposed under the mirror247may have the number of pixels corresponding to the number of pixels of the line scan camera which is the photographing unit243. For example, if the number of pixels of the line scan camera is 4,000, the lenses are configured to provide corresponding to the 4,000 pixels. In this case, the lens242may be referred to as a4K lens. When the lens242and the line scan camera, which is the photographing unit243, are combined together, the visibility of the image of the inspection object250can be improved.

The lens242may also be disposed above the mirror247. That is, when the lens242is disposed in the lens barrel241, no additional lens should be disposed in the lens barrel241. When the lens242is disposed in the lens barrel241, the lens barrel241serves to connect the lens242to the photographing unit243, and the lens242in the lens barrel241serves to transmit light having passed through the mirror247to the photographing unit243.

An auxiliary camera may be further disposed around the light source245. The auxiliary camera may be for monitoring the thickness of the inspection object250not for inspecting the inspection object250.

Accordingly, the optical inspection unit240according to the embodiment of the present disclosure separates the light into spectra by the prism246, increases the reflectance of the inspection object250at a plurality of wavelengths, and increases the intensity of the light by the mirror247. Accordingly, the thickness of the transparent film, i.e., the inspection object250can be measured, so that the defect in the inspection object250can be easily detected. The visibility of the image of the inspection object250can be improved by the lens242disposed above or below the mirror247.

By providing the photographing unit243included in the optical inspection unit240, it is possible to detect defects in the entire substrate on which the encapsulation layer is formed. Then, by converting the thickness of the encapsulation layer, which is the inspection object250, into the thickness according to the intensity of the light, it is possible to quantify the defect of the transparent film when the inspection object250is a transparent film.

A method of detecting a defect in an inspection object will be described with reference toFIGS. 6 and 7.

Referring toFIG. 7, red, green, blue and white light from the light sources245, illuminate the inspection object250on the substrate11.

Referring toFIG. 6, the light from the light sources245is reflected by the mirror247toward the inspection object250. The reflective light reflected from the inspection object250passes through the mirror247again and is transmitted to the photographing unit. InFIG. 7, the dotted line represents the surface reflection, and the one-dot chain line represents the interface reflection. When the light is reflected from the inspection object250, the surface reflection and the interface reflection are synthesized, such that the intensity of the light of the inspection object250is changed. The photographing unit243converts the reflective light reflected from the inspection object250into the intensity of the light while scanning the inspection object250.

When the inspection object250is scanned using light, light is continuously reflected from the inspection object250. The photographing unit243collects light continuously reflected from the inspection object250and continuously outputs a photocurrent. The intensity of the photocurrent varies in proportion to the intensity of the light. Therefore, a change in the intensity of the light can be known from a change in the photocurrent. The light is differently reflected from the inspection object250depending on the characteristics of the encapsulation layer, which is the inspection object250, and the intensity of the light changes depending on a defect in the encapsulation layer. By detecting the intensity of the light of the inspection object250and detecting the thickness of the inspection object250according to the light intensity by using the method, it is possible to efficiently inspect whether there is a defect in the encapsulation layer.

When a defect in the inspection object250is inspected by the above-described method, the time taken for detecting a defect in the inspection object250may be equal to the time taken for scanning the inspection object250. This is because the detecting unit248detects a defect in the inspection object250during the scanning time of the inspection object250. In detail, the optical inspection unit240scans along the inspection area of the inspection object250once in the x-axis or the y-axis direction. Subsequently, during the scanning along the next inspection region, a process of comparing the data of the previously scanned inspection area with the data stored in the detection unit248and analyzing datum are performed, to determine whether there is a defect. Therefore, the inspection time of the inspection object250can be reduced.

According to an embodiment of the present disclosure, it is possible to efficiently detect a defect when the inspection object250is a transparent film by detecting a defect in the encapsulation layer which is the inspection object250with the thickness according to the intensity of the light.

And, according to an embodiment of the present disclosure, when the encapsulation layer, which is the inspection object250, is formed by ink-jet printing, it is possible to detect a defect that may occur when the encapsulation layer is not applied or insufficiently applied on the substrate. By doing so, a defect in the encapsulation layer can be detected in advance, before the post-processes of the cell or the module process. Therefore, the yield and productivity of the OLED device can be improved.

According to an embodiment of the present disclosure, it is possible to detect a defect due to variations in the thickness of an encapsulation layer by detecting a defect in the encapsulation layer with a thickness converted in accordance with the intensity of the light. That is, if the encapsulation layer is formed by ink-jet printing, it is possible to detect defects due to particles, defects caused when the encapsulation layer is not applied or insufficiently applied due to the clogging of a nozzle of an inkjet, defective formation of the encapsulation layer due to poor spreading of the ink, defects due to insufficient or excessive application of the encapsulation layer caused by increase or decrease in the amount of the ink discharged from a nozzle, defects caused by variations in the curing conditions for curing the encapsulation layer, defects due to the overflow of the encapsulation layer, etc.

According to an embodiment of the present disclosure, the step of detecting defects in the inspection object can be performed while scanning a new inspection area, so that the inspection time can be shortened.

According to an embodiment of the present disclosure, an inspection method comprises irradiating light through a prism to an inspection object; scanning an inspection region of the inspection object using a photographing unit; receiving, by the photographing unit, reflected light that is reflected from the inspection object; converting the reflected light received by the photographing unit into an intensity of light; and detecting a defect of the inspection object by comparing a thickness of the inspection object corresponding to the intensity of the light with a predetermined thickness of the inspection object. Therefore, the encapsulation layer is inspected before post-processes of cells or the module process, such that the yield and productivity of the OLED device or apparatus can be improved.

The method may further include separating the light from a light source into spectra by the prism; reflecting the separated light toward the inspection object by a mirror; and passing the reflected light from the inspection object through the mirror.

The wavelength of the light from the light source may be within a range from 400 nm to 900 nm.

The mirror may include a half-mirror.

The photographing unit may include a line scan camera.

The detecting a defect of the inspection object may be performed while a different inspection region of the inspection object is scanned.

The inspection object may include an encapsulation layer of an organic light-emitting panel.

The inspection object may include a transparent film of an organic light-emitting panel.

The inspection method may be implemented prior to post-processes of the organic light-emitting panel.

The irradiating light to the inspection object may further include irradiating the light through a lens disposed above or below the mirror.

According to an aspect of the present disclosure, an inspecting apparatus comprises an optical inspection unit including a prism configured to separate light emitted from a light source into spectra; a mirror configured to reflect the separated light toward an inspection object; a photographing unit configured to receive a reflected light that is reflected from the inspection object and to convert the reflected light into an intensity of light; and a detection unit configured to detect a defect of the inspection object by comparing a thickness of the inspection object corresponding to the intensity of the light with a predetermined thickness of the inspection object. Accordingly, it is possible to easily detect a defect in an inspection object with the thickness according to the intensity of the light irradiated onto the inspection object.

The wavelength of the light emitted from the light source may be within a range from 400 nm to 900 nm.

The mirror may include a half-mirror.

The mirror may include an angle adjusting unit

The inspection object may include an encapsulation layer of an organic light-emitting panel.

The encapsulation layer may include a particle cover layer.

The inspection object may include a transparent film of an organic light-emitting panel.

The photographing unit may include a line scan camera and display a color image.

The apparatus may further include an alignment camera configured to align the inspection object with the optical inspection unit.

The apparatus may further include an auto focusing unit configured to adjust focus of the optical inspection unit with respect to the inspection object when the optical inspection unit moves along an inspection region of the inspection object.

The apparatus may further include a lens having a pixel number corresponding to a number of pixels of the photographing unit.

The detection unit may convert the intensity of the light into the thickness of the inspection object corresponding to the intensity of the light.

The inspection apparatus may be disposed prior to a device for post-processes of the organic light-emitting panel.

Thus far, embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the embodiments, and modifications and variations can be made thereto without departing from the technical idea of the present disclosure. Accordingly, the embodiments disclosed in the present disclosure and the accompanying drawings are used not to limit but to describe the spirit of the present disclosure. The scope of the present disclosure is not limited only to the embodiments and the accompanying drawings. Therefore, it should be understood that the above-described embodiments are not limiting but illustrative in all aspects. The scope of protection sought by the present disclosure is defined solely by the appended claims and all equivalents thereof are construed to be within the true scope of the present disclosure.