JP2007147903A - Static electricity warning device for display panel and manufacturing method for display panel using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely protect a display panel against static electricity. <P>SOLUTION: Static electricity generated when protective films 16 and 17 are peeled off from polarizers 14 and 15 of a liquid crystal panel 10 flows through a ground line 32 connected to a display driving circuit to be discharged to a ground potential G. At this time, the current flowing through the ground line 32 is detected by a current transformer 33 and its detected current signal is compared with a reference value by an abnormality detecting circuit 35. Consequently, when the current flowing through the ground line 32 exceeds a critical value, a warning signal is output to a notification circuit 44 to warn an operator. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a static electricity warning device for a display panel and a method for manufacturing a display panel using the same.

  The liquid crystal display device has a configuration in which a backlight, which is an external light source, is assembled on the back side of a liquid crystal panel. The liquid crystal panel has a configuration in which a liquid crystal is sandwiched between a pair of glass substrates and a polarizing plate is attached to each of the outer surface sides of both glass substrates. Among these, although the protective film for protecting the surface is affixed on the outer surface of a polarizing plate, this protective film is peeled in a manufacturing process so that it may mention later.

  A switching element such as a TFT, a bus line connected to the switching element, and a terminal portion arranged at the end of the bus line are formed on the inner surface side of one glass substrate of the liquid crystal panel. A driver is connected to the driver and a printed circuit board is connected to the driver, and a display drive signal is supplied to the printed circuit board from an external circuit.

  In the manufacturing process of the liquid crystal display device described above, an operation of sandwiching a liquid crystal panel obtained by attaching a polarizing plate with a protective film on the outer surfaces of both glass substrates between a bezel and a frame formed in a frame shape together. However, prior to that, it is necessary to perform the work of peeling off the front and back protective films. When this protective film is peeled off, static electricity is generated, and there is concern that the static electricity may adversely affect the switching elements and drivers of the liquid crystal panel.

In order to prevent such electrostatic breakdown, it is conceivable that the display drive circuit of the liquid crystal panel is grounded when the protective film is peeled off. In addition, what was described in the following patent document 1 is known as a technique for preventing electrostatic breakdown in the process of manufacturing such a liquid crystal panel.
JP-A-10-186299

  However, the static electricity generated at the initial stage of the peeling operation tends to be excessive and tends to be excessive, and there is a possibility that the generated static electricity may be excessive due to variations among workers. When such excessive static electricity is generated, there is a possibility that the driver and the switching element may be electrostatically destroyed even though the display driving circuit of the liquid crystal panel is connected to the ground potential as described above.

  The present invention has been completed based on the above circumstances, and an object thereof is to reliably protect a display panel from static electricity.

  A static electricity warning device for a display panel according to the present invention is used when static electricity generated when an external treatment is applied to a display panel provided with a display drive circuit, and is connected to the display drive circuit. A ground line connecting this to the ground potential, a current detection circuit for detecting a current flowing through the ground line, a current detection signal from the current detection circuit is compared with a reference value, and a current flowing through the ground line is critical. And an abnormality detection circuit that outputs a warning signal when the value is exceeded.

  In this way, even if static electricity is generated when an external treatment is applied to the display panel, the static electricity flows through the ground line connected to the display drive circuit and is released to the ground potential. At this time, the current flowing through the ground line is detected by the current detection circuit, and the current detection signal is compared with the reference value by the abnormality detection circuit. As a result, when the current flowing through the ground line exceeds a critical value, a warning signal is output.

The following configuration is preferable as an embodiment of the present invention.
(1) Provide recording means capable of recording a signal corresponding to the current flowing through the ground line. This is useful for analyzing the occurrence of static electricity.

(2) Provide a notification circuit that notifies a warning based on the warning signal. Thereby, the operator can be alerted.

(3) The abnormality detection circuit includes a peak hold circuit that holds positive and negative peak values in the current detection signal from the current detection circuit, and a comparison circuit that compares each positive and negative peak value with a predetermined reference value. . Thereby, it can be detected and compared with the reference value regardless of whether the current flowing through the ground line is positive or negative.

(4) A self-diagnosis circuit is provided that outputs an error signal when a state in which no current flows through the ground line continues for a predetermined time based on the current detection signal from the current detection circuit. Thereby, it is possible to detect a situation where the ground line is not connected to the display drive circuit of the display panel, such as the ground line being disconnected.

  According to the present invention, since the abnormality of static electricity can be detected by the abnormality detection circuit, the display panel can be reliably protected from static electricity.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an electrostatic warning device 30 used in the manufacturing process of the liquid crystal panel 10 constituting the liquid crystal display device is shown.

  First, the structure of the liquid crystal display device will be described. The liquid crystal display device has a configuration in which a liquid crystal panel 10 for displaying an image and a backlight (not shown) that emits light from the back side of the liquid crystal panel 10 are assembled to each other. Among these, the backlight includes a large number of linear light sources such as cold cathode tubes arranged in a line, and the surface facing the liquid crystal panel 10 converts light from the linear light source into a planar shape. It is set as the structure with which the several optical sheet of these was laminated | stacked.

  As shown in FIGS. 1 and 2, the liquid crystal panel 10 is formed by bonding a pair of transparent glass substrates 11 and 12 facing each other with a predetermined gap therebetween by a spacer, and both the glass substrates 11 and 12. A configuration is adopted in which a liquid crystal 13 whose optical characteristics are changed by voltage application is sandwiched therebetween. Polarizing plates 14 and 15 are attached to the outer surface sides of the glass substrates 11 and 12, respectively, and protective films 16 and 17 for protecting the surfaces are attached to the outer surface sides of the polarizing plates 14 and 15, respectively. It is attached. The protective films 16 and 17 are peeled off in the manufacturing process of the liquid crystal display device.

  A switching element such as a TFT connected to a source bus line (source wiring) and a gate bus line (gate wiring) orthogonal to each other is provided on the inner surface of the glass substrate 12 on the back side of the glass substrates 11 and 12 on the front side. On the inner surface of the glass substrate 11, R, G, and B pixel electrodes are provided in a matrix. A terminal portion connected to each bus line is provided on a side end portion of the glass substrate 12 on the back side, and a thin film driver (electronic component) 18 such as SOF (System On Film) is provided in this terminal portion. One end side of each is crimped and connected via an ACF (anisotropic conductive film). A printed circuit board 19 is crimped to the other end of the driver 18 via an ACF. The printed circuit board 19 is provided with a connector portion 20 that serves as a terminal of the display drive circuit described above. An FPC constituting an external circuit is inserted into the printed circuit board 19 so that it can be connected to display an image. Necessary display drive signals are supplied from an external circuit. In FIG. 1, two printed circuit boards 19 are connected to the liquid crystal panel 10.

  The liquid crystal panel 10 is held in a state of being sandwiched between a front-side bezel and a back-side frame (both bezels not shown) both formed in a frame shape, and the bezel or frame is held against the backlight. Thus, a liquid crystal display device is configured. Therefore, in the manufacturing process of the liquid crystal display device, it is necessary to peel off the protective films 16 and 17 attached to the outer surfaces of the polarizing plates 14 and 15 before the bezel and frame are assembled.

  Then, the electrostatic warning apparatus 30 used at the time of the peeling operation | work of the protective films 16 and 17 is demonstrated. As shown in FIG. 3, the electrostatic warning device 30 is roughly connected to an FPC 31 (Flexible Printed Circuit) whose one end is connectable to the connector portion 20 of the printed circuit board 19 and the other end of the FPC 31. And a ground line 32 connected to the ground potential G, a current transformer 33 for detecting a current flowing through the ground line 32, and an amplifier for amplifying a current detection signal output from the current transformer 33 34 and an abnormality detection circuit 35 connected to the amplifier 34.

  One end of the FPC 31 can be inserted into and removed from the connector portion 20, while the other end is always connected to the ground potential G via the ground line 32. Therefore, in a state where one end side of the FPC 31 is inserted into the connector portion 20, static electricity generated on the liquid crystal panel 10 side can be released to the ground potential G. The current transformer 33 outputs +, − (positive / negative) current detection signals to the amplifier 34 based on the current flowing through the ground line 32.

  Next, the abnormality detection circuit 35 will be described in detail. The abnormality detection circuit 35 includes a buffer 36 connected to the amplifier 34, a + peak hold circuit 37 and a −peak hold circuit 38 connected to the buffer 36, and a + analog comparator 39 connected to the + peak hold circuit 37, respectively. A -analog comparator 40 connected to the peak hold circuit 38; a + reference voltage generation circuit 41 connected to the + analog comparator 39; a reference voltage generation circuit 42 connected to the analog comparator 40; And a data logger 43 connected to the + peak hold circuit 37 and the −peak hold circuit 38.

  The + peak hold circuit 37 can hold a + (positive) peak value in the current detection signal output from the buffer 36. On the other hand, the −peak hold circuit 38 can hold a − (negative) peak value in the current detection signal output from the buffer 36. The data logger 43 can record the + peak value and the −peak value output from the + peak hold circuit 37 and the −peak hold circuit 38.

  The + analog comparator 39 can compare the + peak value output from the + peak hold circuit 37 and the + reference voltage output from the + reference voltage generation circuit 41. As a result, the + peak value is When it exceeds the + reference voltage, it is determined that the + current flowing through the ground line 32 exceeds the critical value, and a warning signal is output. Similarly, the analog comparator 40 can compare the peak value output from the peak hold circuit 38 and the reference voltage output from the reference voltage generation circuit 42 as a result. When the peak value exceeds the reference voltage, it is determined that the current flowing through the ground line 32 exceeds the critical value, and a warning signal is output. The critical value of the current flowing through the ground line 32 is set to a value before the switching element of the liquid crystal panel 10 and the driver 18 are electrostatically destroyed.

  A notification circuit 44 and a self-diagnosis circuit 45 are connected to the abnormality detection circuit 35 described above. Among these, the notification circuit 44 includes a warning notification circuit 46 connected to the + analog comparator 39 and the −analog comparator 40, and a warning notification device 47 connected to the warning notification circuit 46. The warning notification circuit 46 can drive the warning notification device 47 based on the warning signal output from the + analog comparator 39 and the −analog comparator 40, and the warning notification device 47 warns the operator. The lamp can be turned on and a warning sound can be emitted.

  The self-diagnosis circuit 45 is connected to the absolute value amplifier 48 connected to the buffer 36, the timer 49 connected to the absolute value amplifier 48, the error notification circuit 50 connected to the timer 49, and the error notification circuit 50. And an error notification device 51. The absolute value amplifier 48 amplifies the positive / negative component of the current detection signal output from the buffer 36 as a positive signal.

  The timer 49 can measure the duration when the detection signal is not output from the absolute value amplifier 48. If the duration exceeds a predetermined time (for example, 10 minutes), an error occurs. Output a signal. The timer 49 is reset when the detection signal is output.

  The error notification circuit 50 can drive the error notification device 51 based on the error signal output from the timer 49. The error notification device 51 can turn on an error lamp toward the worker, Can be issued.

  This embodiment has the structure as described above, and the operation thereof will be described subsequently. In the manufacturing process of the liquid crystal display device, the polarizing plates 14 and 15 with the protective films 16 and 17 are respectively attached to the outer surfaces of the glass substrates 11 and 12 of the liquid crystal panel 10, and then the driver 18 and the printed circuit board 19 are attached. Work to make a crimp connection. Then, an operation of sandwiching the liquid crystal panel 10 between the frame and the bezel is performed. Prior to that, as shown in FIG. 2, an operation of peeling off the front and back protective films 16 and 17 is performed. Before performing the peeling operation, the FPC 31 of the static electricity warning device 30 is inserted into the connector portion 20 of the printed circuit board 19 and the display drive circuit is electrically connected to the ground potential G.

  When the worker peels off the protective films 16 and 17 from the glass substrates 11 and 12, peeling electrification occurs. When the charged static electricity is discharged toward the terminal portion of the liquid crystal panel 10, there is a concern that the switching element, the driver 18 and the like connected to the terminal portion may be electrostatically damaged. However, the discharged static electricity is released (removed) to the ground potential G through the FPC 31 and the ground line 32 connected to the display drive circuit. Electric breakdown is prevented.

  Here, the current flowing through the ground line 32 is detected as follows. That is, when a current flows through the ground line 32, a positive / negative current detection signal is output from the current transformer 33 based on the current value as shown in FIG. The current detection signal is amplified by the amplifier 34 and input to the buffer 36 of the abnormality detection circuit 35. Among the current detection signals output from the buffer 36, the + peak value is held by the + peak hold circuit 37, and the-peak value is held by the-peak hold circuit 38.

  The + peak value output from the + peak hold circuit 37 and the + reference voltage output from the + reference voltage generation circuit 41 are both input to the + analog comparator 39 and compared there. On the other hand, the −peak value output from the −peak hold circuit 38 and the −reference voltage output from the −reference voltage generation circuit 42 are both input to the analog comparator 40 and compared there. As a result, when the + peak value exceeds the + reference voltage or when the −peak value exceeds the −reference voltage, the + current or −current flowing through the ground line 32 exceeds the critical value. And a warning signal is output from the + analog comparator 39 or the −analog comparator 40. Both the + peak value output from the + peak hold circuit 37 and the −peak value output from the −peak hold circuit 38 are output to the data logger 43 and recorded therein.

  The warning signal output from the + analog comparator 39 or the −analog comparator 40 is input to the warning notification circuit 46 of the notification circuit 44. The warning notification circuit 46 drives the warning notification device 47 based on the warning signal. As a result, a warning lamp is turned on or a warning sound is emitted by the warning notification device 47, so that the operator is encouraged to suppress the generated static electricity by reducing the momentum and speed of peeling off the protective films 16 and 17. It is. Accordingly, the generation of excessive static electricity is suppressed, and a situation in which the switching element of the liquid crystal panel 10 and the driver 18 are electrostatically destroyed is avoided.

  When the oscilloscope 52 is connected to the amplifier 34 during the peeling operation, a current detection signal waveform as shown in FIG. 4 is obtained.

  By the way, before performing the peeling operation, the operation of inserting the FPC 31 into the connector portion 20 is performed. However, this operation has been forgotten or the grounding wire 32 has been disconnected in the middle of the liquid crystal panel. There is a possibility that the peeling operation may be performed in a state where the ten display drive circuits are not connected to the ground potential G.

  In this case, since no current detection signal is output from the buffer 36, no detection signal is output from the absolute value amplifier 48 of the self-diagnosis circuit 45. Based on this, the timer 49 measures the time during which no detection signal is input. If the duration exceeds a predetermined time, it is determined that the display drive circuit is not connected to the ground potential G, and an error signal is output from the timer 49. Then, since an error signal is input to the error notification circuit 50, an error lamp is turned on or an error sound is emitted by the error notification device 51 driven based on the error signal. You are prompted to check the status of line 32 and the like.

  Accordingly, it is possible to prevent the peeling operation from being performed while the generated static electricity is not released to the ground potential G, thereby avoiding a situation in which the switching element of the liquid crystal panel 10 and the driver 18 are electrostatically destroyed. It has become. When the peeling operation is performed with the display drive circuit of the liquid crystal panel 10 connected to the ground potential G, a current detection signal is output from the buffer 36 to the absolute value amplifier 48 from the current detection signal, and the absolute value amplifier Since the detection signal is output from 48, the timer 49 resets the measured time.

  As described above, according to this embodiment, static electricity generated when the protective films 16 and 17 of the polarizing plates 14 and 15 are peeled from the liquid crystal panel 10 is released to the ground potential G through the ground line 32. At this time, the current flowing through the ground line 32 is detected by the current transformer 33, and the current detection signal is compared with the reference value by the abnormality detection circuit 35. As a result, when the current flowing through the ground line 32 exceeds the critical value. Since the warning signal is output, abnormality of static electricity can be detected, and thus the liquid crystal panel 10 can be reliably protected from static electricity.

  Further, since the signal corresponding to the current flowing through the ground line 32 is recorded by the data logger 43, it is useful for analyzing the occurrence of static electricity.

  In addition, as the warning signal is input, the warning is notified to the worker who performs the peeling operation by the notification circuit 44, so that the worker can be alerted.

  Further, the abnormality detection circuit 35 holds + and − peak hold circuits 37 and 38 for holding + and − peak values in the current detection signal from the current transformer 33, and sets + and − peak values to + and −. Since the + and-analog comparators 40 are compared with each other, the current flowing through the ground line 32 can be detected and compared with the reference value regardless of the direction of the + or-current.

  In addition, the self-diagnosis circuit 45 that outputs an error signal when a state in which no current flows through the ground line 32 continues for a predetermined time based on the current detection signal from the current transformer 33 is provided. It is possible to detect a situation in which the ground line 32 is not connected to the display drive circuit of the liquid crystal panel 10, such as being disconnected.

<Embodiment 2>
A second embodiment of the present invention will be described with reference to FIG. In the second embodiment, a shunt resistance method is employed in measuring the current flowing through the ground line 32. The second embodiment has the same structure, operation, and effect except that the current transformer 33 and the amplifier 34 described in the first embodiment are removed, and redundant description is omitted. It shall be.

  As shown in FIG. 5, a current measuring resistor 53 is connected in series at a position between the ground potential G and the FPC 31 (not shown) in the ground line 32. The input terminal of the buffer 36 is connected to the end of the current measuring resistor 53 on the FPC 31 side. Accordingly, when a current flows through the ground line 32 as the peeling operation is performed, a voltage detection signal corresponding to the current is input to the buffer 36. The voltage detection signal is input to the + peak hold circuit 37, the −peak hold circuit 38, and the absolute value amplifier 48.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the above-described embodiment, the case where the worker performs the peeling work has been described. However, the present invention can also be applied to the case where peeling is performed using an automatic peeling device. In that case, a warning signal output from the abnormality detection circuit may be fed back to the automatic peeling device so that the peeling speed is automatically reduced or the peeling work is automatically stopped.

  (2) In the above-described embodiment, the static electricity warning device used in the step of peeling off the protective film of the polarizing plate is exemplified, but the step of applying another type of external treatment to the liquid crystal panel (for example, a vacuum-adsorbed glass substrate It may be used in the removing step.

  (3) In the above-described embodiment, the case where a current transformer or a current measurement resistor is used as the current detection circuit has been described. However, for example, other types of current detection circuits such as a clamp-type ammeter may be used. .

  (4) In the above-described embodiment, the case where the abnormality detection circuit is an analog circuit has been described. However, the abnormality detection circuit may be changed as appropriate, and may be a digital circuit, for example.

  (5) In the above embodiment, the FPC is exemplified as the connection component for the display drive circuit of the liquid crystal panel. However, other types of connection components such as FFC may be used.

  (6) In the above-described embodiment, the static electricity warning device used in the manufacturing process of the liquid crystal panel has been exemplified, but those used in the manufacturing process of other types of display panels such as PDP are also included in the present invention.

1 is a schematic plan view of a liquid crystal panel and a static electricity warning device according to Embodiment 1 of the present invention. Schematic sectional view of liquid crystal panel and static electricity warning device Block diagram of electrostatic warning device Diagram showing the waveform of the current detection signal displayed when connected to an oscilloscope Block diagram of electrostatic warning device according to embodiment 2 of the present invention

Explanation of symbols

10 ... Liquid crystal panel (display panel)
18 ... Driver (display drive circuit)
19 ... Printed circuit board (display drive circuit)
20 ... Connector (display drive circuit)
30 ... Static electricity warning device 32 ... Ground wire 33 ... Current transformer (current detection circuit)
35 ... anomaly detection circuit 37 ... + peak hold circuit (peak hold circuit)
38 ...- peak hold circuit (peak hold circuit)
39 ... + Analog comparator (comparison circuit)
40 ...- analog comparator (comparison circuit)
43 ... Data logger (recording means)
44 ... Notification circuit 45 ... Self-diagnosis circuit 53 ... Current measurement resistor (current detection circuit)
G ... Ground potential

Claims (6)

It is used to remove static electricity generated when external treatment is applied to a display panel having a display drive circuit,
A ground line connected to the display drive circuit and connecting it to a ground potential;
A current detection circuit for detecting a current flowing through the ground line;
An abnormality detection circuit that compares a current detection signal from the current detection circuit with a reference value and outputs a warning signal when the current flowing through the ground line exceeds a critical value. Panel electrostatic warning device. 2. The static electricity warning device for a display panel according to claim 1, further comprising recording means capable of recording a signal corresponding to a current flowing through the ground line. 3. The static electricity warning device for a display panel according to claim 1, further comprising a notification circuit that notifies a warning based on the warning signal. The abnormality detection circuit includes a peak hold circuit that holds positive and negative peak values in a current detection signal from the current detection circuit, and a comparison circuit that compares each positive and negative peak value with a predetermined reference value. 4. A static electricity warning device for a display panel according to claim 1, wherein the static electricity warning device is a display panel. 2. A self-diagnosis circuit that outputs an error signal when a state in which no current flows through the ground line continues for a predetermined time based on a current detection signal from the current detection circuit. 5. The static electricity warning device for a display panel according to claim 4. 6. A display panel manufacturing method, wherein a display panel is manufactured using the electrostatic warning device according to claim 1.

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