KR102092070B1 - Method for inspecting display apparatus - Google Patents

Abstract

The present invention provides a method for preventing a display device from being damaged by a failure between a printed circuit board and a flexible cable, and inspecting a display device for detecting a location of a defective connection, connecting the flexible cable to the printed circuit board (A), applying a test signal to the flexible cable (B), moving the test signal from the flexible cable to the printed circuit board and returning to the flexible cable again (C), and the flexible cable It may include the step (D) of checking the feedback signal transmitted from.

Description

Inspection method of display device {METHOD FOR INSPECTING DISPLAY APPARATUS}

The present invention relates to an inspection method of a display device for inspecting a fastening state between a control board, a printed circuit board and a flexible cable.

Recently, the display industry has tended to seek display devices with improved quality in the direction of high resolution and large area. Accordingly, a display device has recently been developed as a Full High Definition Television (FHD) and an Ultra High Definition Television (UHD), which is approximately 4 times the area of the FHD, and continues to develop as a large size and high quality thin display device. have.

A conventional display device includes a display panel for displaying an image, a panel driving unit supplying driving signals such as a driving power supply and control signals driving the display panel, and a support cover supporting the display panel and the panel driving unit do. The panel driving unit includes a control board supplying a driving signal, a printed circuit board connected to a display panel, and a flexible cable transmitting a driving signal from the control board to the printed circuit board.

The flexible cable is fastened to a connector formed on the printed circuit board. At this time, in a conventional display device, if the alignment between the pad formed on the printed circuit board and the pad formed on the flexible cable does not exactly match, the connection between the pads is in a bad state, and a short occurs during driving.

However, according to the trend of the display industry described above, a conventional display device requires a driving signal of a higher voltage to be essential, and a plurality of flexible cables must be connected to a printed circuit board. Accordingly, as the number of fastening processes between the printed circuit board and the flexible cable increases, the conventional display device increases the defective rate of fastening, and the fastening confirmation process is repeated, resulting in a problem of deteriorating work efficiency.

In addition, in the related art, it is necessary to visually check the fastening state of all flexible cables fastened to the printed circuit board. However, in the conventional inspection method, since the flexible cables are individually checked, the inspection time is delayed, and if it is abnormally fastened, there is a problem of damaging the flexible cable and the display device due to a short circuit generated when a driving signal is applied. In addition, the conventional inspection method has a problem of reducing the work efficiency due to repetition of the inspection process, and consequently, the productivity of the display device.

The present invention has been devised to solve the above-mentioned problems, and it is technical to provide a method of inspecting a display device for preventing a display device from being damaged by a defective connection between a printed circuit board and a flexible cable, and detecting a location of a defective connection. Make it a task.

In addition, an object of the present invention is to provide a method for inspecting a display device to prevent a decrease in yield of a display device as an inefficient inspection process is repeated.

A method of inspecting a display device according to the present invention for achieving the above-described technical problem includes connecting (A) a flexible cable with a printed circuit board, applying (B) a test signal to the flexible cable, and the test signal And moving from the flexible cable to the printed circuit board and returning to the flexible cable again (C), and checking (D) the feedback signal transmitted from the flexible cable.

According to the solution means of the above problems, the present invention improves the normal fastening rate of the flexible cable by automating the inspection process of the display device, thereby shortening the inspection time, thereby increasing the yield of the display device.

1 is a schematic rear view for explaining a display device according to the present invention.
2 is an exploded perspective view showing a main part of a display device for explaining a method of inspecting a display device according to the present invention.
3 is a schematic plan view illustrating a method of inspecting a display device according to a first embodiment of the present invention.
4 is a schematic block diagram for explaining an operation unit.
5 is a schematic plan view illustrating a method of inspecting a display device according to a second embodiment of the present invention.
6 is a schematic plan view illustrating a method of inspecting a display device according to a third embodiment of the present invention.

It should be noted that in this specification, in addition to reference numerals to the components of each drawing, the same components have the same number as possible, even if they are displayed on different drawings.

On the other hand, the meaning of the terms described in this specification should be understood as follows.

It should be understood that a singular expression includes a plurality of expressions unless the context clearly defines otherwise, and the terms "first", "second", etc. are intended to distinguish one component from another component, The scope of rights should not be limited by these terms.

As used herein, the terms “comprises” or “haves” are intended to designate the presence of implemented features, numbers, steps, acts, components, parts, or combinations thereof, as well as one or more other features or It should be understood that the presence or addition possibilities of numbers, steps, actions, components, parts or combinations thereof are not excluded in advance.

The term " connected " as used herein means to include not only a case in which one component is directly connected to another component but also a component indirectly connected to another component through a third component.

The term "on" is meant to include not only the case where a certain component is formed on the upper surface of another component, but also when a third component is interposed between these components.

In this specification, the terms "left" and "right" are for distinguishing one component from other components, and the directionality is not limited or the scope of rights is not reduced by these terms.

The terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention.

Hereinafter, a preferred embodiment of a method for inspecting a display device according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic rear view for explaining a display device according to the present invention, and FIG. 2 is an exploded perspective view showing a main part of a display device for explaining a method for inspecting a display device according to the present invention.

1 and 2, the display device 1 includes a display panel 10 displaying an image and a panel driving unit driving the display panel 10.

The display panel 10 is for displaying an image, and various types of panels such as a liquid crystal display panel and an organic light emitting display panel may be applied. Among them, taking the organic light emitting display panel as an example, the display panel 10 includes a lower substrate and an upper substrate bonded to each other.

The lower substrate is a flexible thin film substrate, and may be made of a plastic material or a metal foil. For example, the lower substrate of the plastic material may be made of any one of polyimide (PI), polyethyleneterephthalate (PET), polyethylenapthanate (PEN), polycarbonate (PC), polynorborneen (PNB), and polyethersulfone (PES). .

The lower substrate includes a plurality of gate lines, a plurality of data lines, a plurality of driving power lines, a plurality of pixels, and a cathode power line.

Each of the plurality of gate lines is formed at regular intervals to cross each of the plurality of data lines, and each of the plurality of driving power lines is formed to be parallel to each of the plurality of gate lines or each of the plurality of data lines. Each of the plurality of pixels is formed in the pixel region defined by the intersecting gate line and data line to display an image according to the gate signal from the gate line and the data signal from the data line.

To this end, each of the plurality of pixels includes a pixel driving circuit connected to the gate line and the data line, and an organic light emitting element connected to the pixel driving circuit and connected to the cathode power line.

The pixel driving circuit includes a switching transistor connected to the gate line and the data line, a driving transistor connected to the switching transistor, and a capacitor connected to the gate electrode and the source electrode of the driving transistor.

The pixel driving circuit supplies the data signal supplied to the data line to the driving transistor according to the switching of the switching transistor according to the gate signal supplied to the gate line to store the gate-source voltage of the driving transistor corresponding to the data signal in the capacitor. . The data current corresponding to the data signal is supplied to the organic light emitting device by turning on the driving transistor with the voltage stored in the capacitor. Here, the transistor may be an a-Si thin film transistor (TFT), poly-Si TFT, oxide TFT, or organic TFT.

The organic light emitting device includes an anode electrode connected to a driving transistor, an organic emission layer formed on the anode electrode, and a cathode electrode formed on the organic emission layer. The organic light emitting device emits light of luminance corresponding to the data current toward the upper portion of the upper substrate by emitting light by a current flowing from the anode electrode to the cathode electrode by turning on the driving transistor.

The cathode power line may be formed on the entire surface of the lower substrate to be electrically connected to the cathode electrode of each pixel or may be formed in a pattern form to be electrically connected to the cathode electrode of the pixels. The cathode power line may be formed to be electrically connected to the organic emission layer of each pixel, and in this case, the cathode electrode may be omitted.

Meanwhile, the display panel 10 may be a liquid crystal display panel, and in this case, the display panel 10 is a non-self-emitting panel and displays an image by adjusting the transmittance of light emitted from the backlight unit. The display panel 10 includes a lower substrate and an upper substrate opposingly bonded with a liquid crystal layer interposed therebetween. The lower substrate controls the light transmittance of the liquid crystal layer by forming an electric field corresponding to the difference voltage between the data voltage applied to each pixel and the common voltage. The upper substrate is configured to include a color filter corresponding to each pixel formed on the lower substrate, and a common electrode to which a common voltage is supplied may be formed according to a driving method of the liquid crystal layer. The upper substrate transmits the color light through the liquid crystal layer and filters the incident light with a color filter so that the color image is displayed on the display panel 10.

The panel driver is for driving the display panel 10, and includes a control board 20, a printed circuit board 30, and a flexible cable 40.

The control substrate 20 generates and supplies driving signals such as driving power and control signals for driving the display panel 10. The control signal may be image data and a timing synchronization signal.

The printed circuit board 30 transmits a driving signal supplied from the control board 20 to the display panel 10. The printed circuit board 30 is connected to the display panel 10, and a flexible circuit film may be interposed between the display panel 10. The printed circuit board 30 may be a printed circuit board (PCB) or a flexible printed circuit (FPC), and driving elements for supplying a control signal to a driving integrated circuit coupled to the flexible circuit film are surface mounted. Is formed. A connector (not shown) for fastening the flexible cable 40 is formed on the printed circuit board 30.

The flexible circuit film is equipped with a driving integrated circuit that supplies a data signal and a gate signal for emitting pixels of the display panel 10. COF (Chip On Film) may be applied to the flexible circuit film.

The driving integrated circuit generates data signals and gate signals based on control signals supplied through a plurality of signal input terminals, and supplies the generated data signals and gate signals to corresponding signal supply terminals, thereby forming each pixel formed on the lower substrate. By driving, the image corresponding to the image data is displayed.

The flexible cable 40 is interposed between the control board 20 and the printed circuit board 30 to transmit a driving signal from the control board 20 to the printed circuit board 30. The flexible cable 40 may be a flexible flat cable (FFC). The flexible cable 40 is fastened to a connector of the printed circuit board 30 to be connected between a pad formed on the printed circuit board 30 and a circuit pad formed on the flexible cable 40.

A plurality of control drive pads 21 to which the flexible cable 40 is coupled are formed on the control substrate 20. The control driving pad 21 serves to move the driving signal to the flexible cable 40.

In addition, a plurality of control test pads are formed on both outermost sides of the control driving pad 21 on the control substrate 20. The control test pad includes a left control test pad 22 formed on the outermost left side of the control substrate 20 and a right control test pad 23 formed on the right outermost side of the control substrate 20. The control test pad serves to move the test signal TS to check whether the control board 20 and the flexible cable 40 are properly coupled.

A plurality of circuit driving pads 31 to which the flexible cable 40 is coupled is formed on the printed circuit board 30. The circuit driving pad 31 serves to move the driving signal from the flexible cable 40 to the printed circuit board 30.

In addition, a plurality of circuit test pads are formed on both outermost sides of the circuit driving pad 31 on the printed circuit board 30. The circuit test pad includes a left circuit test pad 32 formed on the outermost left side of the printed circuit board 30 and a right circuit test pad 33 formed on the outermost right side of the printed circuit board 30. do. The circuit test pad serves to move the test signal TS to check whether the printed circuit board 30 and the flexible cable 40 are properly coupled.

A test line 34 connecting the left circuit test pad 32 and the right circuit test pad 33 is further formed on the printed circuit board 30. The test line 34 serves to move the test signal TS between the left circuit test pad 32 and the right circuit test pad 33.

The flexible cable 40 is provided with a plurality of input driving pads 41 to which the control board 20 is coupled. The input driving pad 41 serves to move the driving signal from the control board 20 to the flexible cable 40.

In addition, a plurality of input test pads are formed on both outermost sides of the input driving pad 41 in the flexible cable 40. The input test pad includes a left input test pad 42 formed on the outermost left side of the flexible cable 40 and a right input test pad 43 formed on the outermost right side of the flexible cable 40. The input test pad serves to move the test signal TS to check whether the control board 20 and the flexible cable 40 are properly coupled.

The flexible cable 40 is formed with a plurality of output driving pads 44 to which the printed circuit board 30 is coupled. The output driving pad 44 serves to move the driving signal from the flexible cable 40 to the printed circuit board 30.

In addition, a plurality of output test pads are formed on both outermost sides of the output drive pad 44 in the flexible cable 40. The output test pad includes a left output test pad 45 formed on the outermost left side of the flexible cable 40 and a right output test pad 46 formed on the outermost right side of the flexible cable 40. The output test pad serves to move the test signal TS to check whether the flexible cable 40 and the printed circuit board 30 are properly coupled.

The flexible cable 40 is formed with a left connection line 47 connecting the left input test pad 42 and the left output test pad 45. The left connection line 47 moves the test signal TS from the left input test pad 42 to the left output test pad 45.

A right connection line 48 connecting the right input test pad 43 and the right output test pad 46 is formed on the flexible cable 40. The right connection line 48 moves the test signal TS from the right output test pad 46 to the right input test pad 43.

The test signals TS moving through the left and right connection lines 47 and 48 may move in opposite directions when arrangements of respective components included in the display device 1 are different.

An operation unit 50 may be coupled to the control substrate 20. The operation unit 50 is a logic circuit composed of an AND gate, and generates a feedback signal FS by performing logical multiplication on the test signals TS. The operation unit 50 may be a field-programmable gate array (FPGA), which is an intermediate development form manufactured to verify the operation and performance of hardware finally before producing the already designed hardware as a semiconductor. A return line 24 connecting the operation unit 50 and the flexible cable 40 is formed on the control substrate 20. The test signal TS supplied from the operation unit 50 is input back to the operation unit 50 through the return line 24. The test signal TS may not be supplied from the operation unit 50 but may be directly supplied from a separate driving signal supply unit.

A result confirmation unit 60 may be disposed on the control substrate 20 to be connected to the operation unit 50. The result confirmation unit 60 may be a confirmation device that receives and displays the feedback signal FS. Specifically, for example, the result confirmation unit 60 may be a voltage meter. Alternatively, the result confirmation unit 60 may be an LED element that emits light when the feedback signal FS is applied.

Hereinafter, a method for inspecting a display device according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic plan view illustrating a method of inspecting a display device according to a first embodiment of the present invention.

2 and 3, a method of inspecting a display device according to the present invention includes the step (A) of connecting a flexible cable 40 with a printed circuit board 30, a test signal TS to the flexible cable 40 ) Applying (B), the test signal (TS) is moved from the flexible cable 40 to the printed circuit board 30 and then returning to the flexible cable 40 again (C), and And (D) checking the feedback signal FS transmitted from the flexible cable 40.

The step (A) of connecting the flexible cable 40 with the printed circuit board 30 includes attaching the output driving pad 44 of the flexible cable 40 to the circuit driving pad 31 of the printed circuit board 30. It is made by combining. Here, the output test pad of the flexible cable 40 is coupled to the circuit test pad of the printed circuit board 30. Specifically, the left output test pad 45 is coupled to the left circuit test pad 32, and the right output test pad 46 is coupled to the right circuit test pad 33. The step (A) may further include the step of connecting the flexible cable 40 to the control substrate 20. Here, the input drive pad 41 and the input test pad of the flexible cable 40 are coupled to the control drive pad 21 and the control test pad of the control board 20, respectively.

Next, the step (B) of applying the test signal TS to the flexible cable 40 is performed by supplying the test signal TS from the control board 20 connected to the flexible cable 40. Here, as the test signal TS, a driving power supply, a driving signal, or the like may be used. The test signal TS may be supplied from a field-programmable gate array 50 disposed on the control substrate 20. In the step (B), the left control test pad 22 is connected to the left input test pad 42 to transmit the test signal TS to the flexible cable 40.

Next, the step (C) of the test signal TS moving from the flexible cable 40 to the printed circuit board 30 and then returning to the flexible cable 40 is the test signal TS It is made by moving between the printed circuit board 30 and the flexible cable 40 through output test pads 45 and 46 formed on the outermost side of the flexible cable 40. Here, in step (C), the test signal TS is between the control board 20 and the flexible cable 40 through input test pads 42 and 43 formed on the outermost side of the flexible cable 40. It is done by moving. In addition, the step (C) is performed by moving the test signal TS through a test line 34 formed to connect the output test pads 45 and 46 to the printed circuit board 30.

This step (C) is a step (C1) of transferring the test signal TS from the flexible cable 40 to the printed circuit board 30, and from the printed circuit board 30 to the flexible cable 40. And transmitting the test signal TS (C2).

In the step (C1), a left connection line 47 connecting the left input test pad 42 and the left output test pad 45 forms the test signal TS to the left output of the flexible cable 40. To the test pad 45, the left output test pad 45 is connected to the left circuit test pad 32 formed on the printed circuit board 30 to transmit the test signal TS to the printed circuit board 30 ).

In the step (C2), a test line 34 connecting the left and right circuit test pads 32 and 33 formed on the printed circuit board 30 connects the test signal TS to the right circuit test pad 33. And the right circuit test pad 33 is connected to the right output test pad 46 formed on the flexible cable 40 to return the test signal TS to the flexible cable 40.

Finally, the step (D) of checking the feedback signal FS transmitted from the flexible cable 40 includes transmitting the test signal TS from the flexible cable 40 to the control board 20, And checking the feedback signal FS generated based on the test signal TS.

The step of transmitting the test signal TS from the flexible cable 40 to the control board 20 is a right connection line 48 connecting the right output test pad 46 and the right input test pad 43. ) Transmits the test signal TS to the right input test pad 43, and the right input test pad 43 is connected to the right control test pad 23 formed on the control board 20 to perform the test. This is achieved by transmitting a signal TS to the printed circuit board 30.

The step of checking the feedback signal FS generated based on the test signal TS is a result confirmation unit 60 disposed on the control substrate 20 after the operation unit 50 generates the feedback signal FS. ) Is made by indicating the fastening state. In this step, the return line 24 connecting the right control test pad 23 and the operation unit 50 transmits the test signal TS to the operation unit 50, and the operation unit 50 provides the feedback. After generating the signal FS, the feedback signal FS may be delivered to the result confirming unit 60.

Here, if the feedback signal FS is the same as the test signal TS, the result confirmation unit 60 determines the fastening state of the flexible cable 40 as normal, and the feedback signal FS is the test If it is different from the signal TS, the fastening state of the flexible cable 40 can be determined as abnormal and displayed.

The inspection method of the display device according to the present invention is to test the inner pins by testing only the outermost pins on both sides that are most displaced when fastened to the connector (not shown) of the printed circuit board 30 in the flexible cable 40. There is an effect that can be confirmed even at the time of tightening. In addition, the inspection method of the display device according to the present invention can easily grasp the fastening state of the flexible cable 40 due to the automated inspection process of checking the fastening state according to the feedback signal FS. Accordingly, the inspection method of the display device according to the present invention can shorten the inspection time compared to the conventional inspection method, which had to visually check the connector fastening state of the printed circuit board 30, thereby improving work efficiency and display. The yield of the device 1 can be improved. In addition, the inspection method of the display device according to the present invention can check the location of the fastening failure of the display apparatus, and thus can take quick action on the failure of the fastening status, and can be applied even after the production of the display apparatus is completed, thereby facilitating maintenance work. Can be done.

4 is a schematic block diagram for explaining an operation unit.

Referring to FIG. 4, a plurality of calculation units 50 may be formed to include first to fourth calculation units 51, 52, 53, and 54. Each of the first to fourth operation units 51, 52, 53, and 54 is for testing each different area of the display panel 10. Specifically, for example, the first operation unit 51 may be a first region R1 of the display panel 10, and the second operation unit 52 may be a second region R2 of the display panel 10, The third operation unit 53 is for testing the third area R3 of the display panel 10, and the fourth operation unit 54 is for testing the fourth area R4 of the display panel 10.

In this case, when a method of inspecting a display device according to the present invention using the calculation unit 50 is described, step (D) transfers the test signal TS from the flexible cable 40 to the calculation unit 50. Step (D1), each of the first to fourth operation units (51, 52, 53, 54) generating a feedback signal (FS) based on the test signal (TS) (D2), and the feedback And a step D3 of confirming each of the signals FS.

In the step D1, each of the plurality of return lines is connected to each of the first to fourth operation units 51, 52, 53, and 54. Each return line 24 transmits the test signal TS to each of the first to fourth operation units 51, 52, 53, and 54 from a printed circuit board driving each region of the display panel 10. To deliver.

In the step D2, the first to fourth arithmetic units 51, 52, 53, and 54 logically perform a test signal TS transmitted from each return line to generate a feedback signal FS.

In the step (D3), each of the feedback signals FS is transmitted to a plurality of result confirmation units 60 connected to the first to fourth operation units 51, 52, 53, and 54, and the display panel 10 ) Can be made by indicating the fastening state of each of the first to fourth regions R1, R2, R3, and R4.

The operation unit may further include a fifth operation unit 55 connected to all of the first to fourth operation units 51, 52, 53, and 54.

When the method for inspecting the display device according to the present invention using the fifth calculation unit 55 is described, in step (D), the fifth calculation unit 55 may include the first to fourth calculation units 51, 52, 53, The method may further include generating a test result signal TRS based on the feedback signals FS generated from 54 (D4) and confirming the test result signal TRS (D5). .

In the step (D4), the fifth operation unit 55 performs a logical multiplication operation on the feedback signal FS transmitted from each of the first to fourth operation units 51, 52, 53, and 54 to generate a test result signal TRS. Can be created.

The step (D5) may be performed by indicating the fastening state of the entire area of the display panel 10 by transmitting the test result signal TRS to the result confirmation unit 60 connected to the fifth operation unit 55. In this case, the step (D5) may be achieved by removing the result confirmation unit 60 from each of the first to fourth operation units 51, 52, 53, 54, and only the fifth operation unit 55.

5 is a schematic plan view illustrating a method of inspecting a display device according to a second embodiment of the present invention. In describing the present embodiment, the same or corresponding description as the previous embodiment will be omitted.

Referring to FIG. 5, the flexible cable 40 may be formed in plural to include first and second flexible cables 40a and 40b. Each of the first and second flexible cables 40a and 40b is coupled to the same control board 20 and the same printed circuit board 30 at different positions. Each of the first and second flexible cables 40a and 40b may be connected to one operation unit 50 through each return line 24a and 24b.

In this case, the step (D) of checking the feedback signal FS transmitted from the flexible cable 40 includes the first test signal TS1 and the second flexible cable transmitted from the first flexible cable 40a ( It comprises a step (D6) for generating a feedback signal (FS) based on the second test signal (TS2) transmitted from 40b), and (D7) for checking the feedback signal (FS).

The step D6 is performed by logically calculating the first and second test signals TS1 and TS2 to generate a feedback signal FS.

The step (D7) is performed by transmitting the feedback signal (FS) to the result confirmation unit (60) to indicate the fastening state.

6 is a schematic plan view illustrating a method of inspecting a display device according to a third embodiment of the present invention. In describing the present embodiment, the same or corresponding description as the previous embodiment will be omitted.

Referring to FIG. 6, the printed circuit board 30 may include first and second printed circuit boards 30a and 30b connected to the first and second flexible cables 40a and 40b, respectively. . The first and second printed circuit boards 30a and 30b may drive the entire region of the display panel 10 or a portion of the display panel 10. For example, when driving the first area R1 of the display panel 10, the first and second printed circuit boards 30a and 30b are coupled to the upper and lower portions of the first area R1, respectively. Can be. Control substrate 20 for driving the first region R1, first and second printed circuit boards 30a, 30b, first and second flexible circuit boards 40a, 40b, and arithmetic unit 50 When the and result checking unit 60 are the first set, the method for inspecting the display device according to the present invention includes the first to fourth to fourth areas R1, R2, R3, R4 of the display panel 10, respectively. The fourth to fourth sets may be combined to check the fastening state of all areas of the display panel 10, respectively. Here, the fifth operation unit 55 may be connected to the first to fourth sets to indicate the fastening state of the entire area of the display panel 10 at a time.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the technical field to which the present invention pertains that various substitutions, modifications and changes are possible without departing from the spirit of the present invention. It will be clear to those who have the knowledge of Therefore, the scope of the present invention is indicated by the following claims, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts should be interpreted to be included in the scope of the present invention.

1: display device 10: display panel
20: control board 21: control drive pad
22: left control test pad 23: right control test pad
24: return line 30: printed circuit board
31: circuit drive pad 32: left circuit test pad
33: right circuit test pad 34: test line
40: flexible cable 41: input driving pad
42: Left input test pad 43: Right input test pad
44: output drive pad 45: left output test pad
46: right output test pad 47: left connection line
48: right connection line 50: operation unit
60: result confirmation unit

Claims (8)

Connecting (A) a flexible cable with a printed circuit board;
Applying a test signal to the flexible cable (B);
(C) returning the test signal from the flexible cable to the printed circuit board and then back to the flexible cable; And
And (D) checking the feedback signal transmitted from the flexible cable,
The step (D) is performed by a calculation unit including first to fourth calculation units for testing different areas of the display panel,
The operation unit further includes a fifth operation unit connected to all of the first to fourth operation units. According to claim 1,
The calculation unit is a method of inspecting a display device disposed on a control panel. According to claim 2,
The step (D),
Transmitting the test signal from the flexible cable to the operation unit (D1);
A step (D2) in which each of the first to fourth operation units generates the feedback signal based on the test signal; And
And checking each of the feedback signals (D3). According to claim 3,
The step (D),
Generating a test result signal based on the feedback signals generated from the first to fourth calculation units (D4); And
And checking the test result signal (D5). The method according to any one of claims 1 to 4,
The flexible cable includes first and second flexible cables,
The step (D),
Generating a feedback signal based on a first test signal transmitted from the first flexible cable and a second test signal transmitted from the second flexible cable (D6); And
And confirming the feedback signal (D2). The method of claim 5,
The step (A) is a method of inspecting a display device wherein the printed circuit board comprises first and second printed circuit boards connected to each of the first and second flexible cables. The method of claim 6,
The test signal is a test method of the display device to move using the output test pads formed on both outermost sides of the pad portion of the flexible cable. The method of claim 7,
The printed circuit board includes a circuit test pad connected to the output test pad, and a test line connecting the circuit test pads.

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