High-speed inspection method for display panel

Abstract

The present invention relates to a high-speed inspection method for a display panel, the method including the steps of: arranging a transmitter and a receiver to face each other and be spaced a predetermined height from each other at one end and the other end of a panel to be inspected, which has a predetermined width and length; tilting each of the transmitter and the receiver at a predetermined angle toward the panel to be inspected; emit ultrasonic waves from the transmitter toward the panel to be inspected; receiving leakage ultrasonic waves leaked from the panel to be inspected among guide ultrasonic waves by the receiver when the ultrasonic waves are converted into the guide ultrasonic waves in the panel to be inspected and propagated along the panel to be inspected; and scanning the ultrasonic waves received from the receiver to determine whether there is a defect in the panel to be inspected and a position of the defect.

Description

High-speed display panel inspection method

[0001] This invention claims the benefit of Korean Patent Application No. 10-2023-0151049 filed with the Korean Intellectual Property Office on November 3, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a high-speed inspection method for a display panel, which determines the presence or absence and location of a defect in a panel to be inspected through data measured by incident light from a transmitting unit in an air-bonded ultrasonic inspection method.

[0003] Typically, various display panels, including OLED, QD-OLED, and OLEDoS, are manufactured through a series of processes and then undergo a series of high-speed inspections. These high-speed inspections not only detect internal defects within the display panel, but also surface defects such as foreign matter and cracks.

[0004] Specifically, in the case of the OLED panel (OLED glass substrate, OLED-GS), a process is performed in which oxides or metal materials such as ITO and IGZO are deposited on a large-area substrate by sputtering under high-temperature vacuum conditions using a cluster sputter device.

[0005] In this case, OLED panels are formed with a large area and a thin thickness (for example, 2500mm×0.4mm for the 8th generation). In particular, since these panels are made of brittle materials, defects such as breakage can occur during the manufacturing process due to vibrations or various other factors. If a defect occurs, the process must be stopped for a certain period of time to address the defect, which can reduce process efficiency.

[0006] To prevent this, defect inspections were conducted using vision cameras or ultrasound during the manufacturing process of display panels.

[0007] However, when inspecting defects using a vision camera, there is a problem in that it is difficult to obtain the desired image due to light reflection caused by vibrations that occur during transport of the OLED panel.

[0008] Furthermore, conventional ultrasound inspection methods utilize a couplant, such as water. This is due to the high attenuation loss and impedance mismatch of ultrasound. The attenuation of the intensity increases with the wavelength of the ultrasound, and the objective is to reduce the impedance difference between the ultrasound transmitter (transducer) and the panel. However, this inspection method is not only slow, but also requires a post-processing step of drying the OLED panel after inspection, which further slows down the inspection speed.

[0009] Additionally, due to the large area of ​​the OLED panel, there are problems such as difficulty in long-distance scanning or areas where it is impossible to determine the presence or location of defects.

[0010] The background technology described above is technical information that the inventor possessed for the purpose of deriving embodiments of the present invention or acquired during the derivation process, and cannot necessarily be said to be publicly known technology disclosed to the general public prior to the filing of the embodiments of the present invention.

[0011] * Patent literature

[0012] Republic of Korea Patent Publication No. 10-2014-0013170 (Published: February 5, 2014)

[0013] To solve the above problem, the present invention provides a high-speed display panel inspection method for determining the presence or absence and location of a defect in a panel to be inspected through data measured by incident light from a transmitting unit in an air-bonded ultrasonic inspection method.

[0014] A high-speed inspection method for a display panel according to an embodiment of the present invention may include the steps of: arranging a transmitter and a receiver facing each other at one end and the other end of a panel to be inspected having a predetermined width and length and spaced apart from each other by a predetermined height; tilting the transmitter and the receiver at a predetermined angle toward the panel to be inspected; irradiating ultrasonic waves from the transmitter toward the panel to be inspected; receiving, with the receiver, ultrasonic waves leaking from the panel to be inspected among the guided ultrasonic waves when the ultrasonic waves are converted into guided ultrasonic waves in the panel to be inspected and propagated along the panel to be inspected; and scanning the ultrasonic waves received from the receiver to determine the presence or absence and location of a defect in the panel to be inspected.

[0015] In particular, in the step of tilting the transmitter and the receiver respectively, the range of the predetermined angle at which the transmitter and the receiver are tilted may be 5° or more and 35° or less from the axis perpendicular to the inspection target panel.

[0016] Additionally, in the step of investigating ultrasonic waves, the range of the wavelength of the ultrasonic waves may be 200 kHz or more and 1 MHz or less.

[0017] Meanwhile, in the step of placing the transmitter and receiver facing each other, they can be placed in the width direction of the panel to be inspected.

[0018] Additionally, in the step of placing the transmitter and receiver facing each other, they can be placed in the length direction of the panel to be inspected.

[0019] Meanwhile, in the step of placing the transmitter and the receiver facing each other, the transmitter and the receiver can be placed at a predetermined height distance from one side and the other side of the panel to be inspected, respectively.

[0020] Additionally, the step of moving the transmitter and receiver so as to face each other in the longitudinal direction of the panel to be inspected may be further included.

[0021] Additionally, the step of moving the transmitter and receiver so as to face each other in the width direction of the panel to be inspected may be further included.

[0022] The high-speed display panel inspection method according to the present invention can easily detect defects in the inspection target panel using ultrasonic waves without a separate medium.

[0023] In addition, the angle and distance between the transmitter and receiver constituting the ultrasonic sensor unit can be easily adjusted to correspond to the size of the display panel to be inspected, thereby improving inspection efficiency and speed.

[0024] The effects that can be obtained from the invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from the description below.

[0025] FIG. 1 illustrates a block diagram of a high-speed inspection method for a display panel according to an embodiment of the present invention.

[0026] FIG. 2 is a schematic diagram illustrating the arrangement of a transmitter and a receiver in a high-speed inspection method for a display panel according to an embodiment of the present invention.

[0027] FIG. 3 illustrates an example of how a transmitter and a receiver are arranged in a high-speed inspection method for a display panel according to an embodiment of the present invention.

[0028] FIG. 4 is a graph showing the induced ultrasonic velocity, propagation distance, and SNR ratio value according to the resonant frequency in a high-speed inspection method for a display panel according to an embodiment of the present invention.

[0029] FIG. 5 is a schematic diagram of an inspection method in a high-speed inspection method for a display panel according to an embodiment of the present invention.

[0030] ※ Explanation of symbols

[0031] 100: Transmitter

[0032] 200: Receiver

[0033] W: Ultrasound

[0034] GW: Guided ultrasound

[0035] LW: Leakage ultrasound

[0036] θ: a given angle

[0037] P: Panel to be inspected

[0038] The present invention will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. The present invention is defined solely by the scope of the claims. Meanwhile, the terminology used in this specification is for the purpose of describing the embodiments and is not intended to limit the present invention.

[0039] Throughout this specification, singular forms also include plural forms unless specifically stated otherwise in the text.

[0040] Throughout this specification, the terms "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, operations and / or elements, and do not exclude other components unless specifically stated to the contrary, but rather include other components.

[0041]

[0042] Hereinafter, the present invention will be described in more detail.

[0043] FIG. 1 illustrates a block diagram of a display panel high-speed inspection method (S1) according to one embodiment of the present invention.

[0044] Referring to FIG. 1, a display panel high-speed inspection method (S1) according to an embodiment of the present invention may include a step of arranging a transmitter and a receiver facing each other (S10), a step of tilting the transmitter and the receiver respectively (S10), a step of irradiating ultrasonic waves from the transmitter (S30), a step of receiving leaked ultrasonic waves with the receiver (S40), and a step of determining a panel to be inspected (S50).

[0045] The inspection target panel is the object to be judged for the presence or absence and location of defects, and may have a predetermined width, length, and thickness. The specifications of the inspection target panel may be formed differently depending on the material and use of the panel. As an example, the inspection target panel may be an OLED panel (OLED glass substrate, OLED-GS), and the specifications of the mother glass may be 2200mm X 2500mm X 0.4mm, which is the 8th generation specification.

[0046] The inspection process can be performed on the inspection target panel while it is being transferred to the cluster sputtering device. That is, the high-speed inspection method for a display panel according to an embodiment of the present invention can be performed before the inspection target panel is received into the inlet of the cluster sputtering device.

[0047] The step (S10) of arranging the transmitter and the receiver facing each other is to arrange the transmitter and the receiver in one area of ​​the inspection target panel, and can be installed with a predetermined height gap between one end and the other end of the inspection target panel. Here, 'one end and the other end of the inspection target panel' may mean the upper or lower side of both ends of the inspection target panel in the inspection target panel having a predetermined width and length. This may be both ends of the width of the inspection target panel and / or both ends of the length of the inspection target panel.

[0048] The step of tilting the transmitter and receiver (S10) is to tilt the transmitter and receiver, which are placed facing each other, at a predetermined angle toward the panel to be inspected.

[0049] FIG. 2 is a schematic diagram illustrating the arrangement of a transmitter and a receiver (200) in a high-speed inspection method (S1) for a display panel according to an embodiment of the present invention. Referring to FIG. 2, a predetermined angle (θ) can be adjusted so that the receiver (200) can easily receive the leakage ultrasonic waves (LW) leaked from the inspection target panel (P) among the induced ultrasonic waves (GW) converted by being incident on the inspection target panel (P) from the ultrasonic waves (W) irradiated from the transmitter (100) toward the inspection target panel (P). Here, ‘tilting at a predetermined angle (θ)’ may mean tilting with respect to an axis (V) perpendicular to one side or the other side of the inspection target panel (P) forming a predetermined width and length.

[0050] In particular, the present invention places the transmitter (100) and the receiver (200) and the inspection target panel (P) at a predetermined height and tilts them at a predetermined angle (θ). This is an air-coupled ultrasonic test, which is different from the existing invention that reduces the difference in impedance by adding a separate medium between the transmitter (100) and the receiver (200) and the inspection target panel (P). That is, the attenuation phenomenon of the guided ultrasonic wave (GW) due to the impedance difference between the transmitter (100) and the air, the air, and the inspection target panel (P) can be minimized even when the guided ultrasonic wave travels a long distance in a short time through the oblique incidence method of the transmitter (100).

[0051] Here, the range of the angle (θ) at which the transmitter (100) and the receiver (200) are inclined can be formed from 5° to 35° from the axis (V) perpendicular to the inspection target panel (P). The angle (θ) at which the transmitter (100) and the receiver (200) are inclined can form the same angle, or can be formed differently as needed.

[0052] In addition, the direction in which the transmitter (100) and the receiver (200) are tilted can be formed to be tilted in opposite directions with respect to the axis (V) perpendicular to the inspection target panel (P) so that the ultrasonic wave (W) irradiated by the transmitter (100) can easily be incident on the receiver (200) after being incident on the inspection target panel (P). That is, when the transmitter (100) is tilted clockwise with respect to the axis (V) perpendicular to the inspection target panel (P), the receiver (200) can be tilted counterclockwise with respect to the axis (V) perpendicular to the inspection target panel (P).

[0053] The separation distance, tilt angle (θ), etc., of the transmitter (100) and receiver (200) can be adjusted by separate devices such as a distance adjustment unit and an angle adjustment unit. These can be adjusted arbitrarily by the user and / or can be automatically adjusted by a set value. In particular, the separation distance of the transmitter (100) and receiver (200) can be adjusted to correspond to the width or length direction of the inspection target panel (P), or by adding a predetermined error to the corresponding length.

[0054] The step (S30) of irradiating ultrasonic waves (W) from a transmitter (100) and the step (S40) of receiving leaked ultrasonic waves (LW) from a receiver (200) are to irradiate ultrasonic waves (W) from the transmitter (100) toward the inspection target panel (P) and receive leaked ultrasonic waves (W) leaked from the inspection target panel (P) through the receiver (200).

[0055] As described above, the present invention is characterized in that the transmitter (100) is tilted at a predetermined angle (θ) from the inspection target panel (P) to cause the ultrasonic wave (W) to be incident obliquely. In this case, the ultrasonic wave (W) incident on the inspection target panel (P) is converted into a guided ultrasonic wave (GW) that propagates along the inspection target panel (P). As the guided ultrasonic wave (GW) propagates, a portion of the ultrasonic wave leaks from the inspection target panel (P), thereby forming a leaky ultrasonic wave (LW), and by receiving a portion of this leaky ultrasonic wave (LW) through the receiver (200), the presence or absence and location of a defect in the inspection target panel (P) can be determined.

[0056] In particular, the wavelength range of the ultrasonic wave (W) irradiated from the transmitter (100) may be 200 kHz or more and 1 MHz or less. The wavelength range may be adjusted depending on the angle (θ) at which the ultrasonic wave (W) is incident on the inspection target panel (P), the type of the inspection target panel (P), etc.

[0057] The step (S60) of determining the presence or absence and location of a defect in the inspection target panel (P) is to extract data related to the defect in the inspection target panel (P) through measurement data of leak ultrasonic waves (LW) via a transmitter (100) and a receiver (200).

[0058] The above data can be collected and converted through a data acquisition system (DAQ system). In addition, according to one embodiment of the present invention, defect data of the inspection target panel (P) can be converted through B mode (B scope).

[0059] B mode is an ultrasonic tomography technique that utilizes pulse reflection. It can determine the location of defects by scanning the cross-section of the inspection target panel (P). Ultimately, B mode can be used to determine the presence and location of defects by observing changes in the amplitude of ultrasonic waves (W).

[0060] Meanwhile, in the step (S10) of arranging the transmitter (100) and the receiver (200) facing each other in the panel (P) high-speed inspection method (S1) according to one embodiment of the present invention, the positions where the transmitter (100) and the receiver (200) are arranged can be adjusted.

[0061] FIG. 3 illustrates an example of how a transmitter and a receiver are arranged in a display panel high-speed inspection method (S1) according to one embodiment of the present invention.

[0062] In one embodiment, as shown in (a) of FIG. 3, the transmitter and receiver may be arranged facing each other in the width direction of the inspection target panel. Alternatively, as shown in (b) of FIG. 3, as another embodiment, the transmitter and receiver may be arranged facing each other in the length direction of the inspection target panel. Furthermore, as shown in (c) of FIG. 3, the transmitter and receiver may be arranged simultaneously in the width and length directions of the inspection target panel. The above arrangement methods may be arranged individually, or may be arranged in at least one or more arrangements.

[0063] Alternatively, the transmitter and receiver may be positioned at a predetermined height distance from one side and the other side of the panel to be inspected, respectively. That is, they may be positioned facing each other on one side of the panel to be inspected, or they may be positioned facing each other on one side and the other side of the panel to be inspected, respectively.

[0064] In addition, a method (S1) for high-speed inspection of a display panel according to an embodiment of the present invention may further include a step (S60) of moving a transmitter and a receiver so that they face each other. The transmitter and receiver may be formed as a pair and moved simultaneously, and may move in the longitudinal direction of the panel to be inspected or in the width direction. If the transmitter and receiver are arranged in multiple pairs, the panel may move simultaneously in the lengthwise and widthwise directions.

[0065] The purpose of adjusting the position and movement direction of the transmitter and receiver is to more quickly and clearly determine the presence and location of defects in the panel to be inspected.

[0066] In other words, for defects formed in directions where the transmitter and receiver face each other, it is somewhat difficult to determine the length and shape of the defect. Consequently, installing the transmitter and receiver in multiple directions offers the advantage of more clearly identifying the presence and location of defects in the inspection panel through data measured from various angles.

[0067] Additionally, there is an advantage in that defects in the panel can be detected at a faster speed by moving the transmitter and receiver in the width and / or length direction of the panel to be inspected.

[0068]

[0069] Hereinafter, an embodiment of a display panel high-speed inspection method (S1) of the present invention for detecting cracks (defects) in a panel to be inspected will be reviewed.

[0070] In a high-speed display panel inspection method (S1) according to one embodiment of the present invention, a high-power pulser / receiver, RITEC RPR-4000, was used as the transmitter and receiver.

[0071] In addition, a high-speed display panel inspection method (S1) according to an embodiment of the present invention applies an oblique incidence method of a transmitter, and when analyzing guided ultrasound under boundary conditions of air between the transmitter and the panel to be inspected, a transmission coefficient and a reflection coefficient can be obtained. Here, the transmission coefficient is expressed as a function of frequency, thickness, and incidence angle, so that when the panel to be inspected is determined, the incidence angle of the transmitter can be determined.

[0072] In one embodiment of the present invention, the inspection target panel was used as an OLED GS, and A0 mode (0th order asymmetric mode) was used. This is because the A0 mode (0th order asymmetric mode), which is highly dispersive in the low-frequency region, has an extremely large transmission coefficient compared to the S0 mode (0th order symmetric mode), which is advantageous for guided ultrasound operation.

[0073] In a high-speed inspection method (S1) for a display panel according to an embodiment of the present invention, a transducer, which is a transmitter, is installed in a pitch-catch manner so that a leak ultrasonic wave (LW) that is irradiated from a panel to be inspected and leaked can be received by a receiver, and the resonant frequencies of the irradiated ultrasonic wave (W) are set to 200 kHz, 500 kHz, and 1 MHz, and the predetermined angles formed by the transmitter, the receiver, and the panel to be inspected are set to 10°, 15.6°, and 20°, respectively. In addition, the width of the substrate to be inspected is set to 2.5 m in order to secure a sufficient propagation distance of the ultrasonic wave (W).

[0074] FIG. 4 is a graph showing the induced ultrasonic velocity, propagation distance, and SNR ratio (signal-to-noise ratio) value according to the resonant frequency in a display panel high-speed inspection method (S1) according to one embodiment of the present invention.

[0075] Referring to Fig. 4, the guided ultrasonic velocity measured at all frequencies is identical to the A0 mode velocity in terms of analysis. However, at the resonant frequency of 500 kHz (Fig. 4 (b)), a longer propagation distance (5.8 m) and a higher SNR ratio were obtained than at 200 kHz (Fig. 4 (a)) and 1 MHz (Fig. 4 (c)). Therefore, in the examples below, experiments were conducted with ultrasonic waves (W) at the resonant frequency of 500 kHz.

[0076] Additionally, the predetermined angle formed by the transmitter, receiver, and inspection target panel at the above resonant frequency was set to 15.6°.

[0077] FIG. 5 is a schematic diagram of an inspection method in a high-speed inspection method for a display panel according to an embodiment of the present invention.

[0078] Referring to Fig. 5, a transmitter and a receiver are installed facing each other in the width direction (x-axis) and length direction (y-axis) of the panel to be inspected, with a predetermined height spaced apart from each other. The transmitter and receiver are tilted at a predetermined angle toward the panel to be inspected, and ultrasonic waves are irradiated from the transmitter.

[0079] Referring to FIG. 5, in a transmitter and a receiver (hereinafter, a first transmitter and receiver) facing each other in the longitudinal direction of the inspection target panel, when the transmitter irradiates ultrasonic waves while simultaneously moving in the width direction of the inspection target panel, the amplitude of the leakage ultrasonic waves received from the receiver moving opposite the transmitter can be confirmed. In addition, in a transmitter and a receiver (hereinafter, a second transmitter and receiver) facing each other in the width direction of the inspection target panel, when the transmitter irradiates ultrasonic waves while simultaneously moving in the longitudinal direction of the inspection target panel, the amplitude of the leakage ultrasonic waves received from the receiver moving opposite the transmitter can be confirmed.

[0080] If a longitudinal crack is formed in the inspection target panel, the amplitude of the leakage ultrasonic wave received from the receiver of the first transceiver may be slightly larger than that of the portion without the crack. On the other hand, the amplitude of the leakage ultrasonic wave received from the receiver of the second transceiver may be observed to be larger than that received from the receiver of the first transceiver.

[0081] As a result, when a transmitter and a receiver are formed simultaneously in the width and length directions of the panel to be inspected, there is an effect that can quickly and accurately determine the presence or absence and location of a defect regardless of the direction of the crack formed in the panel to be inspected.

[0082]

[0083] Although the present invention has been described above with reference to limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. A step of placing a transmitter and a receiver facing each other at one end and the other end of a test target panel having a predetermined width and length and spaced apart by a predetermined height; A step of tilting the transmitter and receiver at a predetermined angle toward the inspection target panel; A step of irradiating ultrasonic waves from the transmitter toward the inspection target panel; When the above ultrasonic waves are converted into guided ultrasonic waves from the inspection target panel and propagated along the inspection target panel, a step of receiving leakage ultrasonic waves leaking from the inspection target panel among the guided ultrasonic waves with the receiver; and A method for high-speed inspection of a display panel, comprising: a step of scanning a leak ultrasound received from the receiver to determine the presence or absence and location of a defect in the inspection target panel.

2. In paragraph 1, In the step of tilting the transmitter and receiver respectively, A high-speed inspection method for a display panel, characterized in that the range of the predetermined angle at which the transmitter and receiver are inclined is 5° or more and 35° or less from an axis perpendicular to the inspection target panel.

3. In paragraph 1, In the step of investigating the above ultrasound, A high-speed inspection method for a display panel, characterized in that the wavelength range of the above ultrasonic waves is 200 kHz or more and 1 MHz or less.

4. In paragraph 1, In the step of placing the transmitter and receiver facing each other, A high-speed display panel inspection method characterized by arranging the inspection target panel in the width direction.

5. In paragraph 1, In the step of placing the transmitter and receiver facing each other, A high-speed display panel inspection method characterized by arranging the inspection target panel in the longitudinal direction.

6. In paragraph 1, In the step of placing the transmitter and receiver facing each other, A high-speed inspection method for a display panel, characterized in that the transmitter and receiver are positioned at a predetermined height apart from one side and the other side of the inspection target panel, respectively.

7. In paragraph 1, A high-speed inspection method for a display panel further comprising a step of moving the transmitter and receiver so as to face each other in the longitudinal direction of the inspection target panel.

8. In paragraph 1, A high-speed inspection method for a display panel further comprising a step of moving the transmitter and receiver so as to face each other in the width direction of the inspection target panel.

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