JP5313590B2 - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device, which is excellent image quality. <P>SOLUTION: According to one embodiment, the image display device includes a substrate, a display part provided on the substrate, in which a plurality of pixel circuits are arranged in a matrix, a driving IC provided adjacent to the display part on the substrate, a plurality of driving signal lines provided to connect the driving IC and the display part to transmit a driving signal from the driving IC to a plurality of the pixel circuits, and a feeder provided between the adjacent driving signal lines out of a plurality of the driving signal lines to supply power supply voltage to a plurality of the pixel circuits from the driving IC side to the display part side. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image display device, for example, an image display device using an organic EL (Electroluminescence) element.

  Conventionally, an image display device using an organic EL (Electroluminescence) element having a function of generating light by recombination of holes and electrons injected into a light emitting layer has been proposed.

In this type of image display device, for example, a thin film transistor (hereinafter referred to as “TFT”) or an organic light emitting diode (hereinafter referred to as “OLED”), which is one of organic EL elements, is used for each pixel. And a display unit in which each pixel is arranged in a matrix. Each pixel emits light by supplying electric power from the power source to each pixel via a power supply line, and setting an appropriate current value to each pixel by an image signal transmitted from the drive IC via the drive signal line. Thus, a desired image is displayed.
In the case of a power supply method in which a predetermined voltage is supplied to each OLED arranged in a matrix from one end side to the other end side, a voltage drop occurs in the power supply line. In addition, the voltage applied to the OLED in the pixel located on the other end side is lowered. For example, when the feeder line is arranged so as to avoid the region where the driving IC is mounted, the influence of the voltage drop is large.

  In view of this, a technique has been proposed in which a feeder line is provided between the driving IC and the display unit to increase the region where the feeder line is formed, thereby reducing the influence of the voltage drop (see Patent Document 1 below). .

  In the technique described in Patent Document 1 described above, the parasitic capacitance between the signal line and the power supply line formed between the driving IC and the display unit is increased, and noise is easily included in the image signal. Accordingly, there arises a problem that an image displayed on the image display device is disturbed.

JP-A-2005-157300

  The present invention has been made in view of the above, and an object thereof is to provide an image display device with excellent image quality.

  An image display device according to an embodiment of the present invention includes a substrate, a display unit provided on the substrate, in which a plurality of pixel circuits are arranged in a matrix, and on the substrate and adjacent to the display unit. A drive IC provided; a plurality of drive signal lines provided to connect the drive IC to the display unit; and a drive signal transmitted from the drive IC to the plurality of pixel circuits; and the plurality of drive signal lines. And a power supply line that is provided between adjacent drive signal lines and supplies a power supply voltage from the drive IC side to the display unit side to the plurality of pixel circuits. .

  Further, in the image display device according to an embodiment of the present invention, the power supply line is inserted one by one between the drive signal lines drawn from the drive IC side toward the display unit side. It is characterized by that.

  In the image display device according to an embodiment of the present invention, the plurality of drive signal lines are arranged as a plurality of groups, and the power supply lines are inserted one by one between the groups. It is characterized by that.

  Further, in the image display device according to an embodiment of the present invention, a plurality of insulating films are interposed between the substrate and the driving IC, and the power supply line is formed in one layer of the insulating film, The power supply line is formed in a different layer from the insulating film on which the power supply line is formed.

  In the image display device according to an embodiment of the present invention, the power supply line includes a first power supply line that is a high potential side power supply line and a second power supply line that is a low potential side power supply line. In addition, the first power supply line and the second power supply line arranged on the second insulating film are arranged so as not to overlap each other in plan view.

  ADVANTAGE OF THE INVENTION According to this invention, the image display apparatus excellent in the image quality can be provided.

  Exemplary embodiments of an image display apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. This embodiment is an example in which an image display device using an organic EL (Electroluminescence) element is applied as an image display device.

  FIG. 1 is a plan view schematically showing a configuration of an image display apparatus 100 according to the first embodiment of the present invention. As shown in FIG. 1, the image display apparatus 100 schematically includes a display unit 20 in which a plurality of pixel circuits 21 (see FIG. 2) are arranged in a matrix on a substrate 10, and each of the display units 20. To the power supply line 30 for supplying the power supply voltage to the pixel circuit 21, the drive signal line 50 connected to each pixel circuit 21, the image signal line 52 (see FIG. 2) and the like, and the drive signal line 50 And a driving IC 40 that controls the supply of the above signal.

  The display unit 20 includes a thin film transistor (hereinafter referred to as “TFT”) or an organic light emitting diode (hereinafter referred to as “OLED”) that is one of organic EL elements. It has pixel circuits arranged in a matrix. A drive signal line 50 is connected to these pixel circuits, and the brightness of each pixel is controlled by a scanning signal and an image signal transmitted via the drive signal line 50, and a desired image is displayed.

  Here, FIG. 2 is a circuit diagram showing a configuration example of the pixel circuit 21. That is, the display unit 20 of the image display device 100 has a configuration in which a plurality of pixel circuits 21 as shown in FIG. 2 are arranged in a matrix.

The pixel circuit 21 shown in FIG. 2 includes an organic light emitting diode OLED, a driving transistor T _d that is driver means for driving the organic light emitting diode OLED, a threshold voltage detecting transistor T _th , a holding capacitor C _s , and the organic light emitting diode OLED itself. Element capacitance C _oled . Next, the configuration, function, etc. of the pixel circuit 21 shown in FIG. 2 will be described.

The drive transistor _Td is a control element for controlling the amount of current flowing through the organic light emitting diode OLED according to the potential difference applied between the gate electrode and the source electrode.

When the threshold voltage detecting transistor _Tth is turned on, the gate electrode and the drain electrode of the driving transistor _Td are electrically connected. As a result, until the potential of the gate electrode to the source electrode of the driving transistor T _d is the threshold voltage V _th of substantially driving transistor T _d, a current flows toward the drain electrode from the gate electrode of the driving transistor T _d, the drive The threshold voltage _Vth of the transistor _Td is detected.

  The organic light emitting diode OLED includes an anode electrode layer and a cathode electrode layer formed of Al, Cu, ITO (Indium Tin Oxide), or the like. Furthermore, the organic light emitting diode OLED has at least a light emitting layer formed of an organic material such as phthalocyanine, trisaluminum complex, benzoquinolinolato or beryllium complex between the anode electrode layer and the cathode electrode layer. It is. When a potential difference (potential difference between the anode electrode layer and the cathode electrode layer) equal to or higher than the threshold voltage of the organic light emitting diode OLED is applied to both ends of the organic light emitting diode OLED, holes and electrons injected into the light emitting layer are applied. Recombine with each other to generate light from the light emitting layer.

The channel (n-type or p-type) for the drive transistor _Td and the threshold voltage detecting transistor _Tth is not particularly specified, but either n-type or p-type may be used. In the present embodiment, each thin film transistor is n-type. Each thin film transistor may be made of amorphous silicon (amorphous silicon), microcrystalline silicon, or polycrystalline silicon (polysilicon).

The power supply line 30 includes a V _DD line 31 as a first power supply line that is a high-potential side power supply line and a _VSS line 32 as a second power supply line that is a low-potential side power supply line. A predetermined power supply voltage is supplied to the transistor _Td .

Scanning line 51 of the driving signal line 50 supplies a signal for controlling the driving of the threshold voltage detecting transistor T _th in the threshold voltage detecting transistor T _th.

Image signal line 52 of the driving signal line 50 supplies the image signal to the storage capacitor C _s.

  Note that the power supply line 30 and the scanning line 51 are connected to the pixel circuits 21 in common. The image signal line 52 is commonly connected to the pixel circuits 21 arranged in the column direction.

  The drive IC 40 includes a switching element and the like, and controls the magnitude of the voltage applied to the scanning line 51 and the timing of application. The drive IC 40 includes an arithmetic circuit and the like, and generates a potential corresponding to image data (hereinafter referred to as “image data potential”) and supplies the generated image data potential to the image signal line 52. To control.

  FIG. 3 is a time chart showing a manner of potential fluctuation of each component of the image display device during operation. In FIG. 3, a scanning line (n−1) shows a time chart of the scanning line 51 and the image signal line 52 corresponding to the pixel circuit 21 located in the previous stage for reference.

First, a first reset process for resetting the potential applied to the gate electrode of the drive transistor _Td during past light emission is performed. Specifically, as shown in the period _{t 1} in FIG. _3, the potential of the _{V DD} line 31 and _{V SS} line 32 is set to the _{V DD,} the potential of the scanning line 51 is set to ON potential. That is, the threshold voltage detection transistor T _th is in an on state.

Electric charges are supplied via the organic light emitting diode OLED, the potential of the first electrode connected to the gate electrode of the driving transistor T _d of the storage capacitor C _s is supplied from the V _DD line 31 to the anode electrode layer of the organic light emitting diode OLED It becomes almost equal to the potential V _DD .

On the other hand, as shown in FIG. 3, since the potential of the image signal line 52 is V _DL , the potential of the second electrode connected to the image signal line of the storage capacitor C _s is V _DL .

Next, as shown in the period _{t 2} in FIG. 3, in the preparation _step, a potential -V _E of _{V DD} line 31, the potential of the image signal line 52 is _{V DH,} the potential of the _{V SS} line 32 If V _DD and the potential of the scanning line 51 is OFF, the potential of the gate electrode of the drive transistor _Td is V _DD + V _DH −V _DL , which is higher than the threshold voltage V _th of the drive transistor T _d. . Further, the threshold voltage detection transistor T _th is in an off state. As a result, the drive transistor _Td is turned on, and the current i flows.

Next, as shown in a period t ₃ in FIG. 3, in the threshold voltage detection step, the potential of the V _DD line 31 is 0 potential, the potential of the image signal line 52 is V _DH , and the potential of the V _SS line 32. Is 0 potential, and the potential of the scanning line 51 is ON potential, the threshold voltage detection transistor _Tth is turned ON. As a result, the current i flows through the threshold voltage detecting transistor _Tth and the driving transistor _Td . When the potential of the gate electrode of the driving transistor _{T d} reaches _{V th,} the drive transistor _{T d} is turned _{off, V th} is detected. Next, the threshold voltage detection transistor _Tth is turned off.

Next, as shown in a period t ₄ in FIG. 3, in the data writing process, the potential of the V _DD line 31 is 0, the luminance potential V _DATA is supplied from the image signal line 52, and the potential of the V _SS line 32. Is 0 potential and the scanning line 51 potential is on potential, the threshold voltage detection transistor _Tth is turned on. Thereby, the potential of the gate electrode of the drive transistor _Td is
α (V _DATA −V _DH ) + V _th
It is said. Α is C _s / (C _s + C _OLED ).

Here, the potential of the cathode electrode of the organic light emitting diode OLED is the same as the potential of the gate electrode of the drive transistor _Td because the threshold voltage detection transistor _Tth is turned on.

Next, as shown in the period _{t 5} in FIG. 3, in the second reset _step, the potential of the _{V DD} line 31 is -V _E, the potential of the image signal line 52 is _{V DH,} the _{V SS} line 32 potential is -V _E, the potential of the scanning line 51 When it is oFF potential, the threshold voltage detecting transistor T _th is turned off. Thereby, the potential of the gate electrode of the drive transistor _Td is
(1-α) (V _DH −V _DATA ) + V _th
It is said. This period _{t 5,} the potential of the cathode electrode layer of the organic light emitting diode OLED, -V _E, and the reset.

Next, as shown in the period _{t 6} in FIG. 3, the light-emitting _step, the potential of the _{V DD} line 31 is _{V DD,} the potential of the image signal line 52 is _{V DH,} the potential of the _{V SS} line 32 0 If the potential of the scanning line 51 is an off potential, a current i _d (= (β / 2) ((1-α) (V _DH −V _data )) ² ) flows through the organic light emitting diode OLED, The organic light emitting diode OLED emits light. Here, the current _{i d} does not depend on the threshold voltage _{V th.}

In the present embodiment, as shown in FIG. 1, with disposing the feed line 30 _{(V DD} line 31 · _{V SS} line 32) between the drive IC40, each located at the bottom of each driving IC40 those from driving IC40 to display unit 20 also during of which the drive signal line 50 drawn at intervals in the predetermined direction so as to arrange the feed line 30 _{(V DD} line _{31, V SS} line 32) is there. More specifically, as shown in FIG. 4, between the solder balls 41, which are small ball-like electrodes (also referred to as bumps) made of solder of the drive IC 40 created by a BGA (Ball Grid Array), a feeder line 30 (V _DD line 31 and _VSS line 32) are provided. In the BGA, an IC is mounted on the upper surface of a substrate, and a dotted lead connected to the IC is installed on the rear surface of the substrate. In order to mount such a drive IC 40 on the substrate 10, solder balls 41 are formed in advance on the BGA leads, and the solder balls 41 are placed in accordance with the mount (drive signal line 50) of the substrate 10. Thereafter, the solder balls 41 are melted and soldered.

In this embodiment, the driving IC40 was created by BGA (Ball Grid Array), not limited to this, the power supply line 30 _{(V DD} line 31 · _{V SS} line 32) at the bottom of the drive IC40 Any surface mount type may be used as long as it can be disposed.

As described above, according to the present embodiment, when a predetermined voltage is supplied from one end side to the other end side of each organic light emitting diode OLED arranged in a matrix, the driving IC 40 draws it to the display unit 20. The feed lines 30 (V _DD lines 31 and _VSS lines 32) are arranged between the drive signal lines 50, so that a plurality of feed lines 30 (V _DD lines 31 and _VSS lines 32) are provided. The power supply voltage can be supplied separately. That is, the parasitic capacitance between the drive signal line 50 and the feed line 30 can be reduced by preventing the drive signal line 50 and the feed line 30 from overlapping each other in plan view. As a result, the amount of noise with respect to the signal transmitted to the display unit 20 through the drive signal line 50 can be reduced, and the image quality of the image display apparatus can be improved.

Further, according to the present embodiment, the region where the power supply line 30 connected to the display unit 20 is formed can be widely formed on one end side of the display unit 20, and power is concentrated on a part of the display unit. Compared with the method, the voltage drop of the entire power supply line 30 (V _DD line 31, _VSS line 32) can be reduced to suppress the occurrence of uneven brightness, and an image display device with excellent image quality can be provided. it can.

  Furthermore, by providing many places where the display unit 20 and the power supply line 30 are connected, it is possible to disperse the concentration of the heat generating points as compared with a method in which power is concentrated on a part of the display unit. . As a result, it is possible to suppress a part of the organic light emitting diode OLED from becoming high temperature. In such a high temperature region, the luminance tends to increase, which may cause luminance unevenness. According to this embodiment, such a problem can be made difficult to occur, and an image display device with excellent image quality can be provided.

Note that power supply from the power supply line 30 (V _DD line 31 and _VSS line 32) to the pixel circuit 21 located at the center of the display unit 20 may be reduced to equalize the voltage drop.

In the present embodiment, has been to insert one by one between the solder balls 41 of the drive IC40 feed line 30 _{(V DD} line _{31, V SS} line 32) as shown in FIG. 4, which It is not limited to. For example, the feeder lines 30 (V _DD line 31 and _VSS line 32) do not necessarily have to be inserted one by one between the solder balls 41. As shown in FIG. 5, the feeder line 30 (V _DD line 31, reduce the number of V _SS line 32), if Yosere by several wires of the drive signal line 50 may correspond to the narrow wiring space.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, the same part as 1st Embodiment mentioned above is shown with the same code | symbol, and abbreviate | omits description.

In the first embodiment, although so as to dispose the feed line 30 _{(V DD} line _{31, V SS} line 32) between the solder balls 41 of the drive IC40, when the distance between the solder balls 41 of the drive IC40 is narrow In some cases, it may be difficult to dispose the power supply line 30 (V _DD line 31, _VSS line 32) between the solder balls 41.

Therefore, in the second embodiment, in which to arrange alternately in different planes and the V _SS line 32 V _DD line 31 by an insulating film interposed between the drive IC40 and the substrate 10.

FIG. 6 is a cross-sectional view showing the periphery of the drive IC 40 of the image display apparatus 100 according to the second embodiment of the present invention. As shown in FIG. 6, the image display device 100 of this embodiment, above the substrate _10, an insulating film _{61 V DD} line 31 is _disposed, and the insulating film _{62 V SS} line 32 are arranged Is provided. The driving IC 40 is disposed on the insulating film 62.

To _{V DD} line 31 which is arranged in the insulating film 61, and the _{V SS} line 32 which is disposed in the insulating film 62, as shown in FIG. 6, it is arranged so as not to overlap each other. The V _DD line 31 and the _VSS line 32 are not short-circuited even if they overlap each other because the insulating films 61 and 62 are interposed therebetween, but between the V _DD line 31 and the _VSS line 32, Since the stray capacitance is generated, which is not preferable, the arrangement of the V _DD line 31 and the _VSS line 32 is not overlapped in plan view.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS. In addition, the same part as 1st Embodiment mentioned above is shown with the same code | symbol, and abbreviate | omits description.

  7 is a plan view of the image display apparatus according to the present embodiment, and FIG. 8 is a cross-sectional view taken along the line AA of the substrate located between the drive IC 40 and the display unit 20 of FIG. FIG. 9 is a cross-sectional view taken along the line BB of the substrate located directly below the drive IC 40 in FIG.

As shown in FIGS. 8 and 9, the insulating film 61 and the insulating film 62 are laminated on the substrate 10, and the V _DD lines 31 and the _VSS lines 32 are alternately arranged in the insulating film 61 to provide insulation. The drive signal line 50 is provided in the film 62. A plurality of contact conductors 51 are provided in the insulating film 62 immediately below the drive IC 40 to connect the drive IC 40 and the drive signal lines 50. The drive IC 40 and the drive signal line 50 are electrically connected through the contact conductor 51.

Further, between the driving IC40 and the display unit 20, _{V DD} line _{31, V SS} line 32 immediately below the drive signal line 50 is not to position, the feed line 30 is patterned. By preventing the arrangement of the feeder line 30 and the drive signal line 50 from overlapping each other in plan view, stray capacitance can be reduced between them. As a result, an image signal with less noise can be supplied to the display unit, and an image display device with excellent image quality can be provided.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. In addition, the same part as 1st Embodiment mentioned above is shown with the same code | symbol, and abbreviate | omits description.

Not limited to those disposed by orthogonal to the feed line 30 _{(V DD} line _{31, V SS} line 32) the longitudinal direction of the drive IC 40. For example, as shown in FIG. 10, the power feed line 30 (V _DD line 31, V _DD line V, V _DD line 31, V V) extends from the direction parallel to the longitudinal direction of the drive IC 40 between the drive IC 40 and the display unit 20 without passing under the drive IC 40. _SS line 32) from the pull respectively, may be drawn out of the feed line 30 _{(V DD} line _{31, V SS} line 32) to the display unit 20 side.

  11 is a cross-sectional view taken along the line CC of the substrate located between the driving IC 40 and the display unit 20 in FIG. 12 is a DD cross-sectional view of the substrate from the drive IC side to the display unit side in FIG. Further, FIG. 13 is a cross-sectional view taken along line EE showing the connection relationship between the drive IC and the drive signal line of FIG.

As shown in FIGS. 11 and 13, the V _DD lines 31 and the _VSS lines 32 are provided in the insulating film 61, and the _VSS lines 32 and the drive signal lines 50 are alternately arranged in the insulating film 62. Has been. _{Here, V SS} line 32 _is routed so as not to contact with the _{V DD} line 31, connected to the _{V SS} line 32 in the insulating film 61 and the _{V SS} line 32 in the insulating film 62 via the contact conductor 34 Has been.

Contact conductor 34, to connect the different VSS line 32 between the upper and lower positions, are provided at positions different from V _SS line 32 overlap each other with the vertical position a in the insulating film 61. As a result, using the contact conductor 34, it is possible to route the V _SS line 32, it is possible to effectively utilize the space between the drive signal line 50 with each other not provided the drive signal line 50 in the insulating film 62 .

1 is a plan view schematically showing a configuration of an image display device according to a first embodiment of the present invention. It is a circuit diagram which shows the structural example of a pixel circuit. It is a time chart which shows the aspect of the electric potential fluctuation | variation of each component of the image display apparatus at the time of operation | movement. It is sectional drawing which shows the relationship between a feeder and drive IC. It is a top view which shows roughly the modification of the structure of the image display apparatus which concerns on the modification of this invention. It is sectional drawing which shows the drive IC periphery of the image display apparatus concerning 2nd Embodiment of this invention. It is a top view which shows roughly the structure of the image display apparatus concerning 2nd Embodiment of this invention. It is AA sectional drawing of the image display apparatus concerning 3rd Embodiment of this invention. It is BB sectional drawing of the image display apparatus concerning 3rd Embodiment of this invention. It is a top view which shows roughly the structure of the image display apparatus concerning 4th Embodiment of this invention. It is CC sectional drawing of the image display apparatus concerning 4th Embodiment of this invention. It is DD sectional drawing of the image display apparatus concerning 4th Embodiment of this invention. It is EE sectional drawing of the image display apparatus concerning 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Board | substrate 20 Display part 21 Pixel circuit 30 Feeding line 31 V _DD line 32 V _SS line 40 Drive IC
50 drive signal line 61 first insulating film 62 second insulating film 70 anisotropic conductive film 100 image display device

Claims (5)

A substrate,
A display unit provided on the substrate and having a plurality of pixel circuits arranged in a matrix;
A driving IC provided on the substrate and adjacent to the display unit;
A plurality of drive signal lines which are provided to connect the drive IC and the display unit and transmit a drive signal from the drive IC to the plurality of pixel circuits;
Provided between the drive ICs and between adjacent drive signal lines among the plurality of drive signal lines, and supplies a power supply voltage to the plurality of pixel circuits from the drive IC side toward the display unit side. and a feed line, wherein the power supply line provided between the adjacent drive signal line is disposed between the bumps of the driver IC, that the image display apparatus according to claim. The image display device according to claim 1,
The image display apparatus, wherein the power supply line is inserted one by one between the drive signal lines drawn from the drive IC side toward the display unit side. The image display device according to claim 1,
The plurality of drive signal lines are arranged as a plurality of groups all together,
The image display device according to claim 1, wherein the feeding lines are inserted one by one between the groups. The image display device according to claim 1,
A plurality of insulating films are interposed between the substrate and the driving IC,
Wherein said feed line to one layer in the insulating film is formed, the plurality of driving signal lines, the power supply lines are formed in different layers with an insulating film formed, an image display apparatus, characterized in that. The image display device according to claim 1 ,
A plurality of insulating films are interposed between the substrate and the driving IC,
The power supply line includes a first power supply line that is a high-potential side power supply line and a second power supply line that is a low-potential side power supply line, and
Wherein said first power supply line which is arranged in the first insulating film of the plurality of insulating films, and the second of said second power supply line which is arranged in the insulating film of the plurality of insulating films, plane It is arranged so as not to overlap each other when viewed, that the image display apparatus according to claim.

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