JP4569194B2 - Light emitting device repair method and manufacturing method, light emitting device repair device and manufacturing apparatus - Google Patents

Description

  One invention relates to a light emitting device including an organic light emitting element. Another invention relates to a method for repairing a light emitting device. Another invention relates to a method for manufacturing a light emitting device. Another invention relates to a repair device for a light emitting device. Another aspect of the present invention relates to a light emitting device manufacturing apparatus.

  Here, the light emitting device is a generic term for electronic devices that use an organic light emitting display as a display device in addition to an organic light emitting display in which an organic light emitting element formed on a substrate is sealed between a substrate and a protective member.

Organic EL (electro
There are two types of drive systems for luminescence display: active matrix drive and simple matrix drive.
The active matrix driving method is a method in which lighting and extinguishing of pixels arranged in a matrix are controlled by switching elements corresponding to each pixel.
On the other hand, the simple matrix driving method is a method in which lighting and extinguishing of pixels arranged in a matrix are controlled by a voltage applied to an intersection of a selection line and a signal line.

  For this reason, an active matrix driving type organic EL display includes a thin film transistor that functions as a switching element, an anode connected to one signal terminal of the thin film transistor, an organic EL layer formed on the anode, The cathode is formed on the upper surface of the organic EL layer.

  Here, an organic EL element is comprised by an anode, a cathode, and the organic EL layer (organic compound layer) pinched | interposed by these. Note that the other signal terminal of the thin film transistor is connected to the signal line, and the control terminal is connected to the selection line.

  On the other hand, in a simple matrix driving type organic light emitting display, each pixel is composed of an organic EL layer sandwiched between a signal line and a selection line. In this case, the thin film transistor as the switching element is disposed on each of the signal line and the selection line.

  In addition, when one pixel is composed of three subpixels of R (red), G (green), and B (blue), or four subpixels obtained by adding (white) to each subpixel, The pixel configuration is applied for the sub-pixel corresponding to each single color. Hereinafter, unless otherwise specified, the minimum display unit will be described as a pixel.

By the way, in the process of forming a large number of pixels, pinholes or the like may be formed in a thin organic EL layer due to minute particles or the like.
When an electrical short circuit is formed between two layers (anode and cathode) sandwiching the organic EL layer by a pinhole or the like, all or part of the current that should flow through the organic EL layer flows to the short circuit. End up.

As a result, a phenomenon occurs in which the organic EL layer does not emit light or becomes dark. A pixel in which this phenomenon occurs is called a dark spot pixel.
For example, when the film thickness of the organic EL layer is very thin (several nm to several tens of nm) (for example, in the case of a top emission type organic EL display), the influence of foreign matters of about 1 μm is very large.

Incidentally, as a countermeasure against the dark spot pixel, Patent Document 1 proposes a technique in which a reverse bias voltage is applied to a defective portion to cause a current to flow, and the defective portion is increased in resistance or insulated by a heat generation phenomenon caused by the current. ing.
JP 2003-51384 A

  FIG. 1 shows a circuit configuration of a pixel portion disclosed in Patent Document 1. Each pixel includes a switching TFT 1, a driving TFT 2, an organic light emitting element 3, and a capacitor 4.

  Here, the gate electrode of the switching TFT 1 is connected to the gate signal line Gi. The source region of the switching TFT 1 is connected to the source signal line Si, and the drain region is connected to the gate electrode of the driving TFT 2.

  The source region of the driving TFT 2 is connected to the power supply line Vi, and the drain region is connected to one electrode of the organic light emitting element 3. The other electrode of the organic light emitting element 3 is connected to the counter power source 5. The capacitor 4 is formed such that each electrode is connected to the gate electrode of the driving TFT 2 and the power supply line Vi.

The potential relationship during normal operation is set so that the power supply line Vi is higher than the counter power supply 5.
On the other hand, the potential relationship at the time of restoration is set so that the counter power supply 5 is higher than the power supply line Vi. This potential relationship is reverse bias. By controlling the driving TFT 2 to be in an ON state in a state in which a reverse bias is applied, a reverse bias current can be supplied to a short circuit parasitic on the organic light emitting element 3.

  However, the repair technique disclosed in Patent Document 1 can be applied only to an organic EL display having a limited structure. That is, when a horizontal drive circuit or a vertical drive circuit is formed on the same substrate as the pixel, a sufficient effect cannot be exhibited.

  This is because when a horizontal drive circuit or a vertical drive circuit is formed, only a pixel at a specific position cannot be continuously controlled to be in an on state. That is, the horizontal drive circuit and the vertical drive circuit have a structure for scanning the drive pulse, and the drive pulse cannot be continuously applied only to a specific position.

  On the other hand, in Patent Document 1, during the repair period, a driving pulse is always applied to the source signal line Si and the gate signal line Gi corresponding to the pixel to be repaired, and the switching TFT 1 and the driving TFT 2 are continuously turned on. It is assumed that it will be maintained.

In addition, the circuit configuration shown in Patent Document 1 requires that the switching TFT 1 and the driving TFT 2 be turned on simultaneously in order to pass a reverse bias current.
However, the switching TFT 1 driven by the horizontal drive circuit and the vertical drive circuit cannot be controlled to be continuously turned on as described above.

Based on this recognition, the inventor proposes the following repair technique.
That is, for a light-emitting device having an organic light-emitting element, its drive circuit, a light-emitting switching element corresponding to the organic light-emitting element, and a horizontal drive circuit for supplying signal data to the light-emitting switching element on the same substrate, the horizontal drive While the circuit is stopped, a repair signal is applied only to the light emitting switching element in the specific region, and a reverse bias voltage is applied between the anode and cathode of the organic light emitting element corresponding to the light emitting switching element. Propose technology to do.

For this reason, the following structure is provided in the light emitting device.
(A) an organic light emitting device having an anode, a cathode, and an organic compound layer sandwiched between the anode and the cathode, and (b)
A driving active element having one signal terminal connected to the anode of the organic light emitting element; (c) a light emitting switching element having one signal terminal connected to the control terminal of the driving active element; and (d) a light emitting element. A signal line connected to the other signal terminal of the switching element, and (e)
A selection line connected to the control terminal of the light emitting switching element; (f) a repair switching element in which one signal terminal is connected to the signal line; and (g) a signal line connected to the other signal terminal of the repair switching element. Repair signal line (h)
A repair element selection line connected to the control terminal of the repair switching element; (i) a power supply line connected to one signal terminal of the drive active element; and (j)
A light emitting device having a cathode voltage supply line connected to a cathode of an organic light emitting element is proposed.

In addition, as the repair device or manufacturing device, after forming the cathode, (a) supply a selection signal to the selection line, and (b) select the repair device corresponding to the organic light emitting device to be repaired in synchronization with the selection signal. Supply selection pulse only to the line (c)
A repair signal is supplied to a repair signal line corresponding to an organic light emitting element to be repaired, and (d) a reverse bias voltage is supplied between a power supply line and a cathode voltage supply line.

That is, a repair device or a manufacturing apparatus is proposed that applies a repair signal (reverse bias voltage) to a specific organic light emitting element through a repair signal line, a repair switching element, and a signal line in order during a repair or manufacturing operation. . Here, the application of the repair signal is continued while the repair switching element is controlled to be closed.
By the way, in the case of this repair device or manufacturing device, it is not necessary to operate the horizontal drive circuit during the repair or manufacturing operation. Therefore, even when the horizontal drive circuit is formed on the same substrate as the organic light emitting element, it is possible to continuously apply the repair signal to one or more specific organic light emitting elements.

  By adopting such a technique, it is possible to selectively repair only a specific region of the organic light emitting elements constituting the light emitting device. That is, a dark spot pixel caused by a minute defect in the organic compound layer can be caused to emit light normally.

  Hereinafter, embodiments of the light emitting device according to the invention will be described. In addition, the well-known or well-known technique of the said technical field is applied about the part which is not illustrated or described in particular in this specification. The embodiment described below is one embodiment of the present invention and is not limited thereto.

(1) Configuration of Display Panel FIG. 2 conceptually shows the system configuration of the organic EL display. In FIG. 2, a circuit corresponding to the minimum light emission unit is represented as a pixel circuit 11. In the case where one pixel is composed of a plurality of subpixels as in a color display organic EL display, the pixel circuit 11 is replaced with a subpixel circuit.

  In the case of this embodiment, the pixel circuit 11 is formed on a glass substrate serving as a base. The pixel circuits 11 are arranged in a matrix in the light emitting area according to the resolution of the organic EL display. The configuration of the pixel circuit 11 will be described later.

  On the substrate, in addition to the pixel circuit 11, a wiring pattern and a drive circuit for normal operation and a wiring pattern and a control circuit for repair are formed. These patterns and circuits are formed using, for example, a low temperature polysilicon process.

  The existing components in FIG. 2 are the selection line 13, the signal line 15, the horizontal drive circuit 17, and the vertical drive circuit 19. Here, the selection line 13 is used to select a plurality of pixel circuits 11 arranged in a matrix in a row unit. Each row corresponds to a scan line. The selection line 13 is generally formed so as to extend in the horizontal direction.

  The signal line 15 is used to supply signal data to the pixel circuit 11 selected by the selection line 13. The signal line 15 is formed to be orthogonal to the selection line 13. The signal line 15 is generally formed to extend in the vertical direction.

The horizontal drive circuit 17 is used to generate signal data to be supplied to the signal line 15. The horizontal drive circuit 17 is used during normal operation.
When performing color display, the horizontal drive circuit 17 rearranges signal data in accordance with the arrangement of emission colors that constitute the organic EL display panel. That is, the horizontal drive circuit 17 rearranges the signal data in accordance with the arrangement of subpixels constituting the pixel.

  The horizontal drive circuit 17 receives an analog voltage signal corresponding to the digital video signal. This analog voltage signal is input from a signal driver circuit (not shown). The analog voltage signal is generated by digital / analog conversion processing of the signal driver circuit.

  The vertical drive circuit 19 is used to generate a selection signal to be supplied to the selection line 13. The vertical drive circuit 19 is used not only during normal operation but also during repair operation.

The repair components in FIG. 2 are a power supply line 21, a cathode voltage supply line 23, a repair element selection circuit 25, a repair element selection line 27, and a repair signal line 29.
Here, the power supply line 21 is connected to the anode side of the organic EL element. A voltage supplied through the power supply line 21 is referred to as a power supply voltage Vcc. On the other hand, the cathode voltage supply line 23 is connected to the cathode side of the organic EL element. The voltage supplied through the cathode voltage supply line 23 is called a cathode line voltage Vcat.

  Incidentally, the power supply voltage Vcc and the cathode line voltage Vcat are respectively supplied from external voltage sources. A bias voltage necessary for normal operation or repair operation is supplied through the power supply line 21 and the cathode voltage supply line 23.

  That is, during normal operation, a forward bias voltage (Vcc> Vcat) is supplied through these supply lines. On the other hand, during the repair operation, a reverse bias voltage (Vcc <Vcat) is supplied through these supply lines.

The repair element selection circuit 25 is used to supply repair signal data (a repair signal) to the signal line 15 corresponding to the repair region among the plurality of signal lines 15 during the repair operation.
The repair element selection circuit 25 includes a plurality of switches 25 </ b> A corresponding to the signal lines 15. A thin film transistor is used for the switch 25A.

  During the repair operation, the repair element selection circuit 25 closes the switch 25A of the signal line 15 corresponding to the repair region, and connects the signal line 15 and the repair signal line 29. Note that the repair element selection circuit 25 opens the switch 25A of the signal line 15 corresponding to the non-restoration region, so that the signal line 15 and the repair signal line 29 are not connected.

  On the other hand, at the time of normal operation, the repair element selection circuit 25 opens all the switches 25A so that the signal line 15 and the repair signal line 29 are not connected.

  When the switch 25A is opened, the end of the signal line 15 on the repair element selection circuit 25 side becomes high impedance. As a result, the voltage applied from the horizontal drive circuit 17 to the signal line 15 is supplied to the pixel circuit 11.

  In this embodiment, the opening / closing control of the individual switches 25 A constituting the repair element selection circuit 25 is realized by a selection signal supplied through the repair element selection line 27. FIG. 2 shows a case where all the switches 25 </ b> A are controlled by one repair element selection line 27.

  However, as shown in FIG. 3, the repair element selection lines 27 may be arranged in a one-to-one relationship with the individual signal lines 15. Alternatively, the repair element selection line 27 may be arranged in a one-to-one relationship with each set of a plurality of signal lines 15.

  For example, the organic EL display may be divided into two left and right regions, and two repair element selection lines may be arranged corresponding to each region. Further, for example, a plurality of sub-pixels constituting one pixel may be set as one set, and the repair element selection line 27 may be arranged corresponding to each set. In these cases, restoration in units of pixels or pairs is possible.

The repair signal line 29 is used to apply signal data (analog voltage) necessary for repair from an externally connected repair device during the repair operation.
FIG. 2 shows a case where one repair signal line 29 is connected to the repair element selection circuit 25. That is, the case where the same signal data is applied in units of rows is shown. However, the repair signal lines 29 may be arranged in a one-to-one relationship with the individual signal lines 15.

  Alternatively, the repair signal lines 29 may be arranged in a one-to-one relationship with each set of a plurality of signal lines 15. For example, when the organic EL display supports color display (when one pixel is composed of a plurality of subpixels), the restoration signal line 29 may be arranged in units of pixels.

  Further, for example, three repair signal lines 29 may be arranged corresponding to each color of R (red), G (green), and B (blue). That is, a common repair signal line 29 may be arranged for each color. In this case, the restoration signal can be applied in units of colors. A circuit example is shown in FIG.

  FIG. 4 shows a case where a plurality of subpixels constituting one pixel are controlled by one repair element selection line 27. In the case of FIG. 4, by arranging the repair element selection line 27 for each pixel, it is possible to apply a repair signal corresponding to each color in units of pixels. Further, in the case of FIG. 4, by arranging the repair element selection line 27 for each set of pixels, it is possible to apply a repair signal corresponding to each color in a set of pixels.

  The signal voltage applied to the repair signal line 29 may be a DC voltage, for example. When a DC voltage is applied, a fixed repair signal (voltage) can be applied to the entire display. Further, for example, a pulsed repair signal (voltage) synchronized with the vertical drive circuit 19 may be applied. In this case, a fixed repair signal (voltage) can be applied only to a specific scanning line (one selection line).

  By appropriately selecting the combination of the repair element selection circuit 25 and the repair element selection line 27 described above, it is possible to apply a potential that satisfies the repair condition only to a specific region. That is, damage to pixels other than the dark spot pixels can be reduced.

(2) Pixel Circuit FIG. 5 shows an equivalent circuit configuration of the pixel circuit 11. The pixel circuit 11 basically includes a switching thin film transistor 31, a capacitor 33, a driving thin film transistor 35, and an organic EL element 37.

  In this embodiment, an N-channel TFT transistor is used as the thin film transistor 31. The gate terminal of the thin film transistor 31 is connected to the selection line 13, and the source terminal is connected to the signal line 15.

  The thin film transistor 31 is selected by applying a high potential to the gate terminal through the selection line 13. For example, 7.0 [V] is applied during normal operation, and 17 [V] is applied during repair operation. In this case, the thin film transistor 31 functions as a closed switch.

  Therefore, the voltage applied to the source terminal through the signal line 15 is output to the drain terminal side. Incidentally, during normal operation, 5 [V] is applied to the signal line 15 for the black level and 1.5 [V] for the white level. Further, during the restoration operation, 17 [V] is applied to the signal line 15 for the black level (non-repair) and 0 [V] for the white level (repair).

On the other hand, the thin film transistor 31 is in a non-selected state when a low potential is applied to the gate terminal through the selection line 13. For example, −8.0 [V] is applied during normal operation, and −3 [V] is applied during repair operation.
In this case, the thin film transistor 31 functions as an open switch. Therefore, the voltage applied to the source terminal through the signal line 15 is not output to the drain terminal.

The capacitor 33 is used to hold the potential applied through the thin film transistor 31 until the next selection period (until a high potential is applied to the gate terminal).
Note that one electrode of the capacitor 33 is connected to the midpoint between the drain terminal of the thin film transistor 31 and the gate terminal of the thin film transistor 35. The other electrode of the capacitor 33 is connected to the power supply line 21.

The thin film transistor 35 is a transistor for driving the organic EL element 37. In this embodiment, a P-channel TFT transistor is used.
The gate terminal of the thin film transistor 35 is connected to the drain terminal of the switching thin film transistor 31. The source terminal of the thin film transistor 35 is connected to the power supply line 21, and the drain terminal is connected to the anode of the organic EL element 37.

The thin film transistor 35 is turned on when the potential applied to the gate terminal is low, and applies the potential of the power supply line 21 to the anode of the organic EL element 37.
On the other hand, the thin film transistor 35 is turned off when the potential applied to the gate terminal is high. That is, the thin film transistor 35 functions as an open switch. Accordingly, the connection between the power supply line 21 and the organic EL element 37 is cut off.

  The organic EL element 37 includes an anode, a cathode, and an organic compound layer sandwiched between them. The organic compound layer includes a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, and the like. Basically, the organic EL element 37 is formed by laminating an anode, an organic compound layer, and a cathode in this order.

However, as the organic EL element 37, a stacked structure in which an anode, a hole injection layer, a light emitting layer, an electron transport layer, and a cathode are stacked in order, or a structure in which a plurality of these stacked structures are stacked (SOLED: transparent
There is also Stacked OLED). The cathode is connected to the cathode voltage supply line 23.

(3) Repair device (creation device)
FIG. 6 shows an embodiment of the repair device 41. The repair device 41 is used by being connected to an organic EL display when repairing the dark spot pixels. This repair work also operates as a light emitting device creation device or manufacturing device having an organic light emitting element in the sense of manufacturing a normally operating organic EL display.

In this embodiment, it is assumed that the organic EL display to be repaired is in a semi-finished product state in the manufacturing process. That is, the state before the signal line driver IC or the like is connected.
Incidentally, it is assumed that the horizontal drive circuit 17 and the vertical drive circuit 19 are formed simultaneously with the light emitting region on the organic EL display.

  In this embodiment, the repair device 41 includes a vertical drive condition generation circuit 43, a bias voltage generation circuit 45, a bias voltage drive circuit 47, a repair element selection control circuit 49, and a repair signal potential generation circuit 51. To do.

The vertical drive condition generation circuit 43 is used to generate two types of selection signal potentials and clock signals that satisfy the drive conditions necessary for restoration.
One selection signal potential is a signal potential used to control the pixel circuit 11 to a selected state. That is, it is a high potential. In this embodiment, it is 17 [V].
The other selection signal potential is a signal potential used to control the pixel circuit 11 to a non-selected state. That is, the potential is low. In this embodiment, it is −3 [V].

These two types of selection signal potentials are applied to the selection line 13 through the vertical drive circuit 19. The clock signal generated together with the selection signal potential is generated for the scanning operation of the vertical drive circuit 19.
The clock signal may be the same as that used during normal operation. However, a clock signal that can control a specific selection line to be in a selected state for a long time may be generated exclusively for the repair operation.

The bias voltage generating circuit 45 is used to generate a bias potential applied to the power supply voltage Vcc and the cathode line voltage Vcat. In this embodiment, a potential of 5 [V] is generated as the power supply voltage Vcc. The cathode line voltage Vcat
As shown, two types of potentials of 0 [V] and 10 [V] are generated.

  Here, the two kinds of potentials are generated in order to apply a forward bias voltage and a reverse bias voltage in an alternating manner. Therefore, when the reverse bias voltage is applied in a DC manner, only 10 [V] is generated as the cathode line voltage Vcat. By applying 5 [V] to the power supply line 21 and 10 [V] to the cathode voltage supply line 23, a reverse bias voltage of 5 [V] can be applied to the organic EL element 37.

The bias voltage drive circuit 47 is used to apply 0 [V] and 10 [V] to the cathode voltage supply line 23 in an alternating manner. That is, it is used for alternately applying a forward bias voltage and a reverse bias voltage to the organic EL element 37.
The reason why the cathode line voltage Vcat is AC driven is to charge a capacitance component parasitic on the organic EL element 37 so that a current easily flows to the short circuit that causes the dark spot.

The repair element selection control circuit 49 is used to control the opening / closing of the switch 25A constituting the repair element selection circuit 25. That is, it is used to apply a reverse bias voltage only to a dark spot or a specific portion of pixels including the dark spot.
The control signals here are generated in a number corresponding to the repair element selection lines 27.

The repair signal potential generation circuit 51 is used to generate a repair signal potential to be applied to the signal line 15 selected by the repair element selection circuit 25.
In this embodiment, it is used to generate 17 [V] as the black level and 0 [V] as the white level. The signal potential here is generated in a number corresponding to the repair signal line 29.

The above-described repair device 41 can also be used for inspection of a repaired part. In this case, the repair device 41 generates a potential necessary for normal operation.
For example, the vertical drive condition generation circuit 43 generates 7.0 [V] as a high potential and −8.0 [V] as a low potential.
Further, for example, the bias voltage generation circuit 45 generates 5 [V] as the power supply voltage Vcc and generates −8.0 [V] as the cathode line voltage Vcat.

Further, it is desirable that the repair device 41 has a horizontal drive condition generation circuit for driving the horizontal drive circuit 17.
That is, it is desirable to have a horizontal drive condition generation circuit that generates a signal potential and a clock signal necessary for driving the horizontal drive circuit 17.
The generated signal potential is preferably 5 [V] and 1.5 [V]. However, it is also possible to supply a signal voltage of the same condition through the repair signal line 29.

(4) Driving Operation Next, the driving operation and driving conditions of the organic EL display will be described. Here, each of the normal operation and the repair operation will be described. A forward bias voltage is applied during normal operation, and a reverse bias voltage is applied during repair operation.

(4-1) Normal Operation During normal operation, an analog voltage signal corresponding to a digital video signal is input to the horizontal drive circuit 17. The analog voltage signal has a black level of 5 [V] and a white level of 1.5 [V].
The horizontal drive circuit 17 switches the signal data in accordance with the pixel arrangement of the organic EL display, and applies the signal data to the corresponding pixel. That is, signal data is applied to the corresponding signal line 15.

On the other hand, the vertical drive circuit 19 applies 7.0 [V] to the selection line 13 to which signal data is to be written.
At this time, the thin film transistor 31 connected to the selected selection line 13 is controlled to be on. As a result, signal data is applied to the gate terminal of the driving thin film transistor 35.

At this time, the signal data is held in the capacitor 33. The signal data is held in the capacitor 33 even after the thin film transistor 31 is switched to the off state.
As a result, the drain current Id corresponding to the gate-source voltage Vgs continuously flows through the thin film transistor 35. This drain current Id is supplied to the organic EL element 37. As a result, the organic EL element 37 emits light continuously.

FIG. 7 shows this operating state. At this time, the power supply voltage Vcc is 5 [V], and the cathode line voltage Vcat is -8.0 [V].
FIG. 8 shows an equivalent circuit example when the organic EL element 37 emits light normally. As shown in FIG. 8, the organic EL element 37 can be represented as a diode-connected thin film transistor 53 and a parasitic capacitance component 55.

Incidentally, in reality, there may be an organic EL element 37 that does not emit light normally.
FIG. 9 shows an example of an equivalent circuit when the organic EL element 37 does not emit light normally. As shown in FIG. 9, the organic EL element 37 can be expressed as a diode-connected thin film transistor 53, a parasitic capacitance component 55, and a resistance component 57.

  When such an equivalent circuit is formed, the drain current Ids flows through the resistance component 57 and does not flow through the thin film transistor 53 or becomes very small. That is, the drain current Ids is not supplied to the light emitting layer, and no light emission phenomenon occurs. This is the generation principle of the dark spot pixel.

(4-2) Repair Operation by DC Reverse Bias Drive In order to eliminate such a dark spot pixel, it is only necessary to eliminate the leak current to the resistance component 57. That is, a physical and chemical external force may be applied to the resistance component 57 constituting the short circuit to destroy (insulate) or increase the resistance.

Here, as shown in FIG. 10, it is considered that a reverse bias voltage is applied and a reverse current Id is allowed to flow only through the resistance component 57.
Here, the diode characteristic of the organic EL element 37 is used. That is, the reverse current Id utilizes the property of flowing through the resistance component 57 when a reverse bias voltage is applied. By passing the reverse current Id through the resistance component 57, the temperature of the defective portion can be increased.

As a result of the temperature rise, the defective part is burned out, evaporated due to vaporization or the like, oxidized or carbonized. As a result, a physical or chemical change such as insulation occurs in the defective portion. That is, the resistance of the resistance component 57 is increased due to the change in composition.
As a result, the leakage current to the resistance component 57 when the forward bias voltage is applied decreases, and the current to the organic EL element 37 increases. That is, the organic EL element 37 can be restored to a normal state.

  For this repair operation, the repair device 41 is connected to the organic EL display, and a reverse bias voltage is applied between the power supply voltage Vcc and the cathode line voltage Vcat. That is, 10 [V] is applied to the cathode voltage supply line 23 and 5 [V] is applied to the power supply line 21.

  Further, a high potential (17 [V]) is applied to the selection line 13 corresponding to the scanning line including the pixel to be repaired. As a result, the thin film transistor 31 on the scanning line is turned on. Note that a low potential (−3 [V]) is applied to the other scanning lines.

  Further, a low potential (0 [V]) is applied to the signal line 15 connected to the pixel to be repaired. Note that a high potential (17 [V]) is applied to the other signal lines. As a result, only the thin film transistor 35 corresponding to the pixel to be repaired is controlled to be on.

By the way, also in the case of this restoration operation, the signal data is held in the capacitor 33. The signal data is held in the capacitor 33 even after the thin film transistor 31 is switched to the off state.
As a result, the thin film transistor 35 is controlled to a state in which the reverse current Id according to the gate-source voltage Vgs can continuously flow.

Thus, the reverse current Id continues to flow through the resistance component 57, and the resistance component 57 can be destroyed (insulated) or increased in resistance. That is, the organic EL element 37 can be repaired.
It is desirable to select a driving condition at the time of restoration that maximizes the effect within a range that does not affect the pixel circuit 11 that is operating normally.

Further, it is desirable that the signal data applied to the thin film transistor 35 through the repair signal line 29 is adjusted to an optimum potential according to the state of the defect.
That is, it is desirable to adjust the amount of reverse current Id flowing through the resistance component 57 by adjusting the gate-source voltage Vgs of the thin film transistor 35. Thereby, the influence on other normal pixel circuits 11 can be minimized.

Similarly, the potential applied as signal data can be determined in consideration of the film pressure of the organic layer constituting the dark spot pixel.
Even in this case, the effect of restoration can be maximized while minimizing the influence on other normal pixel circuits 11.

(4-3) Repair Operation by AC Reverse Bias Drive As shown in FIG. 10, when the organic EL element 37 is considered as an equivalent circuit, the presence of the capacitive component 55 cannot be ignored. Depending on the size of the capacitance component 55, the reverse current Id cannot be efficiently passed through the resistance component 57.

Therefore, a case where the reverse bias voltage is AC driven will be described.
FIG. 11 shows the driving conditions of this embodiment. That is, a method is proposed in which the power supply voltage Vcc is fixed at 5 [V] while the cathode line voltage Vcat is switched between 0 [V] and 10 [V] in an AC manner.

Here, when 0 [V] is applied to the cathode line voltage Vcat, a forward bias voltage of 5 [V] is applied to the organic EL element 37.
On the other hand, when 10 [V] is applied to the cathode line voltage Vcat, a reverse bias voltage of 5 [V] is applied to the organic EL element 37. This bias voltage value is a value considering the breakdown voltage of the film thickness of the organic layer including the light emitting layer. In the examples, the film thickness is
It is considered as 100 to 200 [nm].

  Next, the driving cycle will be considered. The inventor was able to obtain good results under the following conditions. That is, the capacitance component 55 is 2 [pF]. Further, the bias voltage to be applied is set to 5 [V] as described above. The reverse current Id that flows when the reverse bias voltage is applied is 6 [μA].

In this case, the time T required to charge the capacitive component 55 can be obtained by the following equation.
T = (2 x ^10-12 ) x 5 / (6 x ^10-9 )
= 1.6 [ms]

In other words, it can be understood that the half cycle is 1.6 [ms] (one cycle is 3.2 [ms]). Therefore, if the reverse bias voltage is AC driven at about 312 Hz, the reverse current Id flowing through the resistance component 57
Can be maximized.

  Actually, optimum conditions are selected according to the capacitance value, reverse current value, and bias voltage. As a result of the experiment, it is desirable that the cathode line voltage Vcat be AC driven at 100 to 600 [Hz], preferably 300 to 400 [Hz]. Incidentally, the AC drive should be continued for 5 to 30 minutes.

  FIG. 12 shows a combination example of the bias voltage applied during AC driving and the potential of the signal data. In FIG. 12, two types of potentials that can be taken by the cathode ray voltage Vcat are shown on the horizontal axis, and two types of potentials that can be taken by the signal data are shown on the vertical axis. That is, four types of combinations are shown.

  In the figure, the operation state shown in the upper left is the case where the driving thin film transistor 35 is controlled to be in the on state and the cathode line voltage Vcat is 10 [V]. In this case, it is understood that a reverse bias voltage of 5 [V] is applied to the organic EL element 37 and a reverse current Id flows.

The operation state shown in the upper right part of the figure represents the case where the driving thin film transistor 35 is controlled to be on and the cathode line voltage Vcat is 0 [V].
In this case, it is understood that a forward bias voltage of 5 [V] is applied to the organic EL element 37 and the drain current Ids flows.
At this time, light is emitted if the organic EL element 37 is in a normal state. Thus, during the repair operation, defect repair can be seen by the dark pixel starting to emit light.

In the drawing, the operation state shown in the lower stage represents the case where the driving thin film transistor 35 is controlled to be in the OFF state. The left side of the lower stage represents the case where the cathode line voltage Vcat is 10 [V].
In this case, since the thin film transistor 35 is in an off state, a reverse bias voltage for repair is not applied. That is, it can be seen that the pixel circuits 11 other than the restoration target are not affected at all.

  The experimental results are shown in FIGS. FIG. 13 is a chart in which how the repair rate (%) is changed for a plurality of samples when the drive frequency of the reverse bias voltage is changed. FIG. 14 is a diagram showing this relationship as a line graph.

Incidentally, an organic EL display panel with three different colors was used in the experiment. 13 and 14 show the restoration results for the green (G) color portion. Of course, other colors can be similarly repaired.
The repair rate is given by the following equation.
Repair rate (%) = (number repaired / number of dark spots before repair) × 100

  In any of the samples, it was confirmed that when the driving frequency was changed from 100 [Hz] to 300 [Hz], the repair rate was improved as the frequency increased. Further, in any sample, it was confirmed that when the driving frequency was changed from 300 [Hz] to 500 [Hz], the repair rate decreased with increasing frequency.

That is, when the driving frequency is around 300 [Hz], the dark spot portion can be restored most efficiently.
From the figure, it is understood that the drive frequency of the reverse bias voltage is preferably 200 [Hz] to 500 [Hz].
However, it is more preferable to set the drive frequency of the reverse bias voltage to 250 [Hz] to 400 [Hz]. More preferably, the drive frequency of the reverse bias voltage is set to 250 [Hz] to 350 [Hz].

In the experiment, a sample having an organic EL element having the structure shown in FIG. 15 was used. The difference in the sample is the difference in the composition of each layer constituting the organic EL element.
The organic EL element has a configuration in which a hole injection layer 63, a hole transport layer 65, a light emitting layer 67, an electron transport layer 69, and a cathode 71 are sequentially stacked on the upper surface of the anode 61.

  Incidentally, the hole injection layer 63 is formed on the upper surface of the anode 61 exposed from the insulating film 73 by etching. Further, a planarizing film 75 is formed under the anode 61 and the insulating film 73, and a polysilicon layer 77 is formed under the lower layer. A drive transistor is formed in the polysilicon layer 77. In the case of FIG. 15, the base is a glass substrate 79. Each EL element is covered with a buffer layer 81 and the surface thereof is covered with a glass sealing layer 83.

(4-4) Correcting Operation by Applying Temperature Next, a case where a reverse bias voltage is applied while heating the dark spot portion will be described. Here, the reverse bias voltage is a DC voltage.

  FIG. 16 shows an apparatus configuration used for this correction operation. FIG. 16 shows a state in which the organic EL display 91 is installed on the heating surface of a hot plate (heating device) 93. The hot plate 93 is provided with a heat source and a temperature control device that controls the temperature to a set temperature.

The set temperature is stored in a semiconductor memory or other storage device. The set temperature can be set arbitrarily by the operator, and one of a plurality of set temperatures prepared at the time of shipment can be selectively used.
The reverse bias voltage is supplied from the correction device 41 connected to the hot plate 93. The internal configuration (FIG. 6) of the correction device 41 is as described above.

17 and 18 show experimental results when a reverse bias voltage is applied in a heated state. The heating time is 20 [minutes]. FIG. 17 is a chart in which how the repair rate (%) changes when the temperature is changed is obtained for a plurality of samples. FIG. 18 is a diagram showing this relationship as a line graph.
Note that the experiment was performed in a state where the temperature of the organic EL element coincided with the set temperature of the hot plate 93.
Moreover, what made the composition of each layer which comprises an organic EL element different was used for each sample.

  As shown in FIGS. 17 and 18, in any sample, when the set temperature is changed from 25 [° C.] (room temperature) to 60 [° C.], the repair rate improves as the temperature increases. confirmed. Further, in any sample, it was confirmed that when the set temperature was changed from 60 [° C.] to 80 [° C.], the repair rate decreased with increasing temperature.

That is, when the temperature was around 60 [° C.], the dark spot portion could be restored most efficiently.
It can be seen from the figure that the temperature is preferably 40 [° C.] to 75 [° C.].
However, the temperature is more preferably set to 40 [° C.] to 65 [° C.]. Further, the temperature is more preferably set to 50 [° C.] to 65 [° C.].
In addition, from the viewpoint of preventing the occurrence of a subsequent dark spot due to thermal diffusion or the like, it is preferable to use a low temperature range where the correction effect is recognized. However, the optimum temperature condition varies depending on the composition of the organic EL element.

(4-5) Correction Operation by Combination of Temperature Application and AC Reverse Bias Drive Here, a case where a reverse bias voltage is applied in an AC manner in a heated state will be described. By combining the reverse bias voltage, AC drive, and heating, a more effective repair operation can be performed.

19 and 20 show the experimental results under these conditions. FIG. 19 is a chart in the case where the temperature and the drive frequency of the reverse bias voltage are changed for one sample. FIG. 20 is a diagram showing this relationship as a line graph.
It was confirmed that similar experimental results could be obtained for other samples, although the repair rates were different.

  In any drive frequency, it was confirmed that when the set temperature was changed from 25 [° C.] (room temperature) to 60 [° C.], the repair rate was improved as the temperature increased. Moreover, in any drive frequency, when the set temperature was changed from 60 [° C.] to 80 [° C.], it was confirmed that the repair rate decreased as the temperature increased.

That is, when the temperature was around 60 [° C.], the dark spot portion could be restored most efficiently.
From the figure, it is understood that the drive frequency is preferably 200 [Hz] to 400 [Hz], and the temperature is preferably 40 [° C.] to 80 [° C.]. However, the drive frequency is preferably 250 [Hz] to 400 [Hz], and the temperature is preferably set to 50 [° C.] to 65 [° C.]. In this case, the repair rate is 20%.

(4-6) Repair Effect As described above, the following effects can be expected by applying the repair method described above.
The repair method described above is also effective when the surface of the organic EL display is completely blocked (sealed) from the outside. This is because there is no need to irradiate laser light from the outside, and defects are repaired internally through current and temperature.

  In the case of a method using laser light, a defective portion cannot be sufficiently repaired due to the influence of glass or a sealing material that blocks the surface of the organic EL display. Further, the method using laser light may damage the filter when a color filter or the like is disposed on the surface of the organic EL display.

  In contrast, the repair method proposed in this specification does not have these drawbacks. Further, in the repair method proposed in this specification, even when a part or all of the scanning line selection circuit and the data line circuit are formed on the same panel as the organic EL element, a reverse bias voltage is applied only to a specific region. Can be applied. Therefore, the dark spot can be repaired efficiently.

  In addition, by applying a reverse bias voltage to the dark spot portion in an alternating manner, excitons are activated to restore the dark spot portion. Further, the kinetic energy of molecules can be suppressed by applying temperature, and the load on the organic EL layer due to the reverse bias voltage can be reduced. Thereby, only the dark spot portion can be selectively repaired. That is, it is not necessary to destroy other normal areas at the time of repair.

(5) Light-emitting device An example of a light-emitting device (electronic device) on which the above-described organic EL display is mounted will be described. Examples of such a light emitting device include a video camera, a digital camera, a head mounted display, a navigation system, a sound reproducing device, a notebook computer, a game machine, a portable information terminal (a portable computer, a cellular phone, a portable game machine, an electronic device, etc. A book, etc.), a clock, an image reproducing device, a monitor, and a television receiver.

  Note that each light-emitting device has a housing, an organic EL display, a signal processing circuit, and an input port. For example, in the case of a television receiver, a speaker and a tuner are mounted in addition to the above-described configuration. In addition to the above-described configuration, the notebook computer or the portable information terminal has operation keys and operation buttons.

Further, in the case of a video camera or a digital camera, in addition to the above-described configuration, an imaging camera and a writing circuit for storing captured video data in a storage medium are provided.
Further, in the case of an electronic device having a communication function such as a mobile phone, in addition to the above-described configuration, a transmission / reception circuit and an antenna as necessary are provided.

(6) Other Embodiments In the above-described embodiments, the case where the organic EL display is formed on the glass substrate has been described. However, the present invention can also be applied to the case where a plastic film substrate is used as the base.

In the above-described embodiment, the case where the light emitting layer corresponding to each color is used as the organic EL display for color display has been described. However, even if the light emitting layer is only white and a color filter is combined therewith to realize color display. good.
Alternatively, the light emitting layer may have only one color, and a color conversion layer may be combined with this to realize color display.

In the above-described embodiment, the case where the reverse bias voltage is basically applied only to the dark spot portion has been described. However, the reverse bias voltage may be applied to a wide region including the dark spot portion. By adopting this application method, the time required for the repair operation can be shortened. This is effective during mass production of organic EL displays.
In this case, the reverse bias voltage is also applied to the normal part, but only the effect of improving the repair rate can be enjoyed by appropriately controlling the application condition.

It is a figure which shows the prior art example of a pixel circuit. It is a figure which shows the structural example of an organic electroluminescent display. It is a figure which shows the example of a connection in the case of giving the signal data for a repair according to a pixel. It is a figure which shows the example of a connection in the case of giving the signal data for restoration according to color. It is a figure which shows the equivalent circuit example of a pixel circuit. It is a figure which shows the Example of a repair apparatus. It is a figure explaining operation | movement at the time of normal operation | movement. It is a figure which shows the flow path of the drain current in a normal pixel. It is a figure which shows the flow path of the drain current in a dark spot pixel. It is a figure which shows the flow path of the reverse current sent for repair. It is a figure which shows the electric potential relationship of the cathode-ray voltage Vcat at the time of alternating current drive, and the power supply voltage Vcc. It is a figure which shows the relationship of the electric potential applied when carrying out alternating current drive of a cathode ray voltage. It is a graph which shows the experimental result at the time of carrying out alternating current drive of a reverse bias voltage. It is a figure which shows the experimental result at the time of carrying out alternating current drive of a reverse bias voltage. It is a figure which shows the structural example of an organic EL element. It is a figure which shows the example of a repair apparatus in the case of applying a reverse bias voltage in a heating state. It is a graph which shows the experimental result in the case of applying a reverse bias voltage in a heating state. It is a figure which shows the experimental result in the case of applying a reverse bias voltage in a heating state. It is a graph which shows the experimental result at the time of carrying out alternating current drive of the reverse bias voltage in a heating state. It is a figure which shows the experimental result at the time of carrying out alternating current drive of the reverse bias voltage in a heating state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Pixel circuit 17 Horizontal drive circuit 19 Vertical drive circuit 21 Power supply line 23 Cathode voltage supply line 25 Repair element selection circuit 27 Repair element selection line 29 Repair signal line 37 Organic EL element 41 Repair apparatus 43 Vertical drive condition generation circuit 45 Bias Voltage generation circuit 47 Bias voltage drive circuit 49 Repair element selection control circuit 51 Repair signal potential generation circuit

Claims (12)

An organic light emitting device having an anode, a cathode, and an organic compound layer sandwiched between the anode and the cathode, a light emitting switching device corresponding to the organic light emitting device, and supplying signal data to the light emitting switching device Upon repairing a light emitting device having a horizontal drive circuit on the same substrate,
While the horizontal drive circuit is stopped, a repair signal is applied only to the light emitting switching element in the specific region, and between the anode and the cathode of the organic light emitting element corresponding to the light emitting switching element. repair method for AC applied to that light emission device a reverse bias voltage. Repair method for a light emitting device according to claim 1 for applying before the Kigyaku bias voltage at 100 Hz to 600 Hz. Wherein upon applying a reverse bias voltage of the repair method of the light emission device of claim 1, the temperature warmed to 35 ° C to 75 ° C and the specific area. An organic light emitting device having an anode, a cathode, and an organic compound layer sandwiched between the anode and the cathode, a light emitting switching device corresponding to the organic light emitting device, and supplying signal data to the light emitting switching device In manufacturing a light emitting device having a horizontal drive circuit on the same substrate,
While the horizontal drive circuit is stopped, a repair signal is applied only to the light emitting switching element in the specific region, and between the anode and the cathode of the organic light emitting element corresponding to the light emitting switching element. method for producing AC applied to that light emission device a reverse bias voltage. The manufacturing method of the light-emitting device according to claim 4, wherein the reverse bias voltage is applied at 100 to 600 hertz. The method for manufacturing a light emitting device according to claim 4, wherein the temperature of the specific region is heated to 35 ° C. to 75 ° C. when the reverse bias voltage is applied. An organic light emitting device having an anode, a cathode, and an organic compound layer sandwiched between the anode and the cathode;
A driving active element having one signal terminal connected to the anode of the organic light emitting element;
A light emitting switching element having one signal terminal connected to a control terminal of the driving active element;
A signal line connected to the other signal terminal of the light emitting switching element;
A selection line connected to a control terminal of the light emitting switching element;
A repair switching element having one signal terminal connected to the signal line;
A repair signal line connected to the other signal terminal of the repair switching element;
A repair element selection line connected to the control terminal of the repair switching element;
A power supply line connected to one signal terminal of the driving active element;
When repairing a light emitting device having a cathode voltage supply line connected to the cathode of the organic light emitting element,
Supplying a selection signal to the selection line;
In synchronization with the selection signal, supply a selection pulse only to the repair element selection line corresponding to the organic light emitting element to be repaired,
Supply a repair signal to the repair signal line corresponding to the organic light emitting device to be repaired,
Between the cathode voltage supply line and said power supply line, repair device light emission device you supply a reverse bias voltage alternating current manner. The light emitting device repairing device according to claim 7, wherein the reverse bias voltage is applied at 100 to 600 hertz. The light-emitting device repairing device according to claim 7, wherein, when the reverse bias voltage is applied, the temperature of a specific region where the organic light-emitting element to be repaired is heated to 35 ° C. to 75 ° C. An organic light emitting device having an anode, a cathode, and an organic compound layer sandwiched between the anode and the cathode;
A driving active element having one signal terminal connected to the anode of the organic light emitting element;
A light emitting switching element having one signal terminal connected to a control terminal of the driving active element;
A signal line connected to the other signal terminal of the light emitting switching element;
A selection line connected to a control terminal of the light emitting switching element;
A repair switching element having one signal terminal connected to the signal line;
A repair signal line connected to the other signal terminal of the repair switching element;
A repair element selection line connected to the control terminal of the repair switching element;
A power supply line connected to one signal terminal of the driving active element;
A cathode voltage supply line connected to the cathode of the organic light emitting device, and after forming the cathode,
Supplying a selection signal to the selection line;
In synchronization with the selection signal, supply a selection pulse only to the repair element selection line corresponding to the organic light emitting element to be repaired,
Supply a repair signal to the repair signal line corresponding to the organic light emitting device to be repaired,
Between the cathode voltage supply line and said power supply line, apparatus for manufacturing a light emission device you supply a reverse bias voltage alternating current manner. The light-emitting device manufacturing apparatus according to claim 10, wherein the reverse bias voltage is applied at 100 to 600 hertz. The light emitting device manufacturing apparatus according to claim 10, wherein the temperature of the specific region is heated to 35 ° C. to 75 ° C. when the reverse bias voltage is applied.

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