JP2007072033A - Display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display which can eliminate or reduce uneven brightness of all the display elements in a simple configuration regardless of the limits in design, such as the minimum conductor width. <P>SOLUTION: The display panel of this display includes scanning electrodes SL1-SL4 and data electrodes DL1-DL4 crossing one another perpendicularly, and organic EL elements arranged in a matrix near their crossing points. The above scanning electrodes and data electrodes are connected to their corresponding drive circuits, respectively by the scanning electrode wiring 102a-102d through the contact section 105 and by the data electrode wiring 103a-103d. The scanning electrode wiring 102a, 102b are laid with redundant wiring length in the area formed when providing a contact 105 near the left of the data electrode wiring 103a. In this simple configuration, variations of the display brightness can be eliminated or reduced by making the conductor resistance even on the scanning electrode wiring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device including a display element whose light emission is controlled by an amount of current passed through an electro-optical element.

  Conventionally, an element whose light emission amount is controlled in accordance with the amount of current flowing through the element, for example, an LED (Light Emitting Diode) typified by an inorganic EL (Electro Luminescence) element or an organic EL element is used as an electro-optical element. There are display elements used. Here, in the present specification, the electro-optical element means an optical element by applying electricity such as FED (Field Emission Display), charge driving element, liquid crystal, E ink (Electronic Ink), in addition to the organic EL element. All the elements whose characteristics change will be referred to. In the following, an organic EL element is illustrated as an electro-optical element, but the same description can be made as long as the light emitting element controls the light emission amount according to the amount of current.

  A display using this organic EL element can emit light with a low voltage and low power consumption, and does not require a backlight. Therefore, it can be made thinner than a liquid crystal display, and in recent years, it is particularly applied to portable devices. Is attracting attention. As a method for driving the organic EL element, a simple matrix method and an active matrix method are known. The active matrix method is a thin film transistor (hereinafter referred to as “TFT”) used in each pixel circuit. ) And the current variation are difficult to control appropriately, and the manufacturing process is complicated and the yield is poor compared to the simple matrix method, so there are many problems in mass production. Therefore, the simple matrix method that can simplify the manufacturing process and reduce the manufacturing cost is often adopted, and a large number of mobile phone display devices and in-vehicle display devices using the simple matrix method are mass-produced. .

  In addition, this organic EL element control method includes a constant voltage control method using a constant voltage source and a constant current control method using a constant current source, depending on the form of a power source that supplies current to the organic EL element. It is divided roughly.

  The constant voltage type control method has a simpler circuit configuration of the power supply than the constant current type control method, so that the manufacturing cost can be reduced. However, in the constant voltage control method, since the power supply voltage is constant, the current flowing through the organic EL element varies due to variations in wiring resistance and the like. In addition, it is known that the light emission luminance and the current flowing during light emission are in a proportional relationship, and this causes variation (unevenness) in the light emission luminance of the organic EL element.

  On the other hand, in the constant current control method, control is performed so that a constant current flows through the organic EL element regardless of the wiring resistance or the like. Therefore, the above-described variation in light emission luminance due to variation in flowing current does not occur. However, in the constant current control method, waveform rounding occurs in the pulse signal of the voltage applied to the organic EL element according to parasitic capacitance, wiring resistance, and the like. Since the luminance of the organic EL element changes according to the waveform rounding, if the wiring resistance or the like varies, the luminance change also varies. As a result, there is no variation in the light emission luminance of the organic EL element as in the constant voltage control method, but there is a variation (unevenness) in the change in the light emission luminance of the organic EL element.

  Here, the constant current type control method can extend the display life of the organic EL element, and the light emission luminance and the current flowing during light emission are in a proportional relationship. Widely used in displays that strictly require gradation reproducibility to display natural images, and exhibits excellent effects.

  On the other hand, a simple display that performs static binary (gradation) display, such as a display used for displaying a title song of a clock or a portable music player, requires a complicated circuit configuration. Instead of the constant current control display, a constant voltage control method with lower manufacturing cost can be adopted.

  By the way, the simple matrix type display is configured such that the wiring resistance is as close to 0 [Ω] as possible, regardless of whether the constant current control method or the constant voltage control method is employed. With this configuration, since the voltage drop due to the wiring resistance is close to 0, in the constant current control method, a voltage close to the power supply voltage (or the voltage obtained by subtracting the voltage drop of the driving IC) is applied to the organic EL element. Can be applied. In addition, the constant voltage control method can increase the light emission luminance by increasing the voltage applied to the organic EL element, and suppress the variation in the voltage drop due to the variation in the wiring resistance value for each wiring. Variation in voltage applied to the EL element, that is, variation in luminance can be suppressed.

For example, conventionally, there is a display device substrate (display panel) in which the width of the wiring increases as the distance from the power source increases (see Patent Document 1). Since the wiring resistance can be lowered by increasing the width of the wiring in this manner, the wiring resistance is almost equal as a result, and variations in voltage applied to the display elements, that is, variations in luminance can be suppressed. In addition, as another configuration for suppressing variation in luminance, there is a display device or the like which has a configuration in which scanning lines or data lines are alternately drawn in different directions (see Patent Document 2).
JP 2004-246330 A JP 2002-299045 A

  Here, as described above, it is preferable to adopt a constant voltage control method with a low manufacturing cost for the simple type display, but this constant voltage type control method suppresses variations in luminance compared to the constant current control method. It is difficult. As described above, the variation in luminance due to the wiring resistance or the like also occurs in the constant current control method.

  In this regard, as in the conventional display device disclosed in Patent Document 1 described above, if the wiring resistance is lowered by increasing the width of the wiring as the distance from the power source decreases, the respective wiring resistances are substantially equal. The variation of can be suppressed.

  However, the above-described conventional display device has a limitation in the actual size of a region (referred to as a frame region) where wiring around the region where the light emitting element is disposed, and the minimum value of the wiring width is manufactured. It does not take into account the limitations of the above technical constraints. Therefore, in the above conventional display device, the resistance values of some wirings cannot actually be made the same as the resistance values of other wirings, so that the luminance varies partially.

  Here, an organic EL element as an electro-optical element is described as an example. However, the present invention is not limited to an organic EL element, and is similar to a light-emitting element whose light emission amount is controlled according to the amount of current flowing through the element. There is a problem.

  Accordingly, an object of the present invention is to provide a display device capable of eliminating or suppressing variations in display luminance in all display elements with a simple configuration regardless of the above limitations.

A first invention is a scan electrode that is a plurality of parallel electrodes extending in a predetermined direction, a data electrode that is a plurality of parallel electrodes extending in a direction orthogonal to the scan electrode, and an intersection of the scan electrode and the data electrode A plurality of electrodes arranged in a matrix to form a plurality of pixels, a scanning electrode for selectively grounding the scanning electrodes for a predetermined period, and a scanning electrode for connecting the scanning electrodes A display device comprising a wiring and a data electrode wiring for connecting the data electrode and a data electrode driving means for selectively passing a current from a power supply for supplying a current to be passed to the electro-optic element to the data electrode ,
Each of the scan electrode wirings has a wiring width and a wiring length that are equal to or larger than a predetermined width so as to have substantially the same resistance value, and has a predetermined width or a width in the vicinity of the predetermined width among the scanning electrode wirings. The two or more scanning electrode wirings have a redundant wiring length.

According to a second invention, in the first invention,
The scan electrode wiring having the redundant wiring length is arranged to bend in a predetermined region between the scan electrode wiring and the data electrode closest to the scan electrode wiring.

According to a third invention, in the first or second invention,
The scanning electrode wiring has a sheet resistance value of 0.2Ω / □ or more.

According to a fourth invention, in any one of the first to third inventions,
The predetermined width is a design minimum width for forming the scan electrode wiring.

A fifth invention is the fourth invention,
The predetermined width is 10 μm.

A sixth invention is any one of the first to fifth inventions,
The electro-optic element is an organic electroluminescence element.

  According to the first aspect of the invention, for example, the resistance values of the scanning electrode wirings cannot be made substantially the same due to limitations (constraints) such as the design of the size of the frame region and the wiring width. However, one or more scanning electrode wirings having a predetermined width or a width in the vicinity of the predetermined width among the scanning electrode wirings are configured so as to have a redundant wiring length (typically routed). Since the resistance values of the scanning electrode wirings can be made substantially the same, variations in display luminance in all display elements can be eliminated or suppressed.

  According to the second aspect of the present invention, the scan electrode wiring having a redundant wiring length is arranged so as to be bent within a predetermined area between the nearest data electrode, so that it has not been used for wiring conventionally. The empty area can be used effectively, and the height of the area and the other wiring area is equalized to some extent by the bent wiring, so that the adhesion by the sealant or the like in the area can be improved. .

  According to the third invention, by setting the sheet resistance value of the scan electrode wiring to 0.2 [Ω / □] or more, it is necessary to use a very expensive metal as a material or to satisfy severe process conditions. This eliminates the need for manufacturing costs.

  According to the fourth aspect of the present invention, the predetermined width described above is set to the minimum design width for forming the scan electrode wiring, so that the predetermined width is formed due to factors such as etching accuracy for forming the scan electrode wiring. It is possible to avoid the possibility that the width of the scan electrode wiring is significantly different from a desired value or that the scan electrode wiring is disconnected.

  According to the fifth aspect, by setting the predetermined width to 10 [μm], this width is set as the minimum design width for forming a general scanning electrode wiring, and the width of the scanning electrode wiring is desired. It is possible to avoid the possibility that the value is significantly different from the above value or that the scan electrode wiring is broken.

  According to the sixth aspect of the invention, a high-quality display device can be easily provided by using an organic electroluminescence element which is a typical electro-optical element.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

<1. Configuration of display device>
<1.1 Overall configuration>
FIG. 1 is a diagram schematically illustrating an overall configuration of a display device according to an embodiment of the present invention. As shown in FIG. 1, this display device is a display device of a simple matrix system, and includes a display panel 100 including a plurality of organic EL elements arranged in a matrix, and a selection for these organic EL elements. A scan electrode driving circuit (also referred to as a common driver circuit or a row driver circuit) 200 and a data electrode driving circuit (also referred to as a segment driver circuit or a column driver circuit) 300 including a plurality of switch circuits for allowing current to flow, and the current And a constant voltage power source 400 for supplying power.

  The constant voltage power supply 400 outputs a determined DC power supply voltage Vdd (for example, 12 [V]) regardless of the load to be driven. Therefore, this display device employs the constant voltage control method described above, and the circuit configuration of the power supply is simpler than that of the constant current control method, so that the manufacturing cost can be reduced.

  The display panel 100 includes four scan electrodes (cathode electrode lines) SL1 to SL4 that are parallel to each other, four data electrodes (anode electrode lines) DL1 to DL4 that are orthogonal to each other, and in the vicinity of these intersections. A plurality of organic EL elements including the organic EL element 10 to be disposed. Here, for convenience of explanation, the number of scan electrodes and data electrodes is four, but in actuality, the number is further larger. For example, the number of scan electrodes is 64, and the number of data electrodes is 96.

  The display panel 100 has a multi-layer structure. For example, an ITO layer to be the data electrode is first formed on a glass substrate, and a hole transport layer made of α-NPD or the like is formed on the ITO layer. A light emitting layer made of a known organic light emitting material is formed thereon, and further, a well known anode buffer layer, electron transport layer, cathode serving as a scanning electrode, and the like are further laminated at appropriate positions. The cathode serving as the scan electrode and the scan electrode wiring are electrically connected through a predetermined contact portion, and this scan electrode wiring is composed of Cr alone, a stacked structure of Cr and Ta, a stacked structure of Cr and ITO, or Cr and It is formed of a metal layer having a laminated structure of Ta and ITO.

  Scan electrodes SL1 to SL4 are connected to scan electrode drive circuit 200, and are supplied with either power supply voltage Vdd or ground potential supplied from constant voltage power supply 400 by the switching operation of the switch circuit included in scan electrode drive circuit 200. Given selectively.

  That is, in one frame period for displaying one display screen, the scan electrode driving circuit 200 sequentially selects one of the scan electrodes SL1 to SL4 and applies a ground potential to each scan electrode that is not selected. Gives the power supply voltage Vdd. FIG. 1 shows a state in which the scan electrode SL2 is selected.

  Note that in this specification, the ground potential refers to a common potential having a predetermined potential difference from the power supply voltage Vdd, and grounding a certain electrode means that the electrode is set to the common potential.

  The data electrodes DL1 to DL4 are connected to the data electrode drive circuit 300, and similarly to the scan electrode drive circuit 200, the power supply voltage supplied from the constant voltage power supply 400 by the switching operation of the switch circuit included in the data electrode drive circuit 300. Either Vdd or ground potential is selectively applied.

  Here, the data electrode driving circuit 300 includes the data electrodes DL1 to DL1 connected to one or more organic EL elements that should emit light among the plurality of organic EL elements connected to one scanning electrode selected by the scanning electrode driving circuit 200. A power supply voltage Vdd is applied to one or more of DL4, and the other data electrodes are grounded. The data electrode drive circuit 300 repeats this operation every time a scan electrode is selected by the scan electrode drive circuit 200. FIG. 1 shows a state where the power supply voltage Vdd is applied to the data electrodes DL1 and DL2. Therefore, only the organic EL element 10 and the organic EL element on the right side thereof emit light here.

  Next, the display panel provided to connect scan electrodes SL1 to SL4 and data electrodes DL1 to DL4 in display panel 100 to scan electrode drive circuit 200 and scan electrode drive circuit 200 provided outside display panel 100. The 100 wirings will be described.

<1.2 Wiring configuration of display panel>
FIG. 2 is a plan view schematically showing the wiring configuration of the display panel 100. As shown in FIG. 2, the display panel 100 includes the above-described scan electrodes SL1 to SL4, scan electrode wirings 102a to 102d whose one ends are connected to the scan electrodes SL1 to SL4 via the contact portion 105, and these Scan electrode connector portion 112 connected to the other end of scan electrode wirings 102a-102d, data electrodes DL1-DL4 described above, and data electrode wirings 103a-103d connected at one end to data electrodes DL1-DL4, And a data electrode connector portion 113 connected to the other ends of the data electrode wirings 103a to 103d.

  As shown in FIG. 2, the scan electrode wiring 102a connected to the scan electrode SL4 and the scan electrode wiring 102b connected to the scan electrode SL3 are longer than the shortest wiring length (wiring distance) satisfying a predetermined design condition. The middle is bent. Further, the scanning electrode wiring 102c connected to the scanning electrode SL2, the scanning electrode wiring 102d connected to the scanning electrode SL1, and the scanning electrode wiring 102a or the scanning electrode wiring 102b have different wiring widths, and the scanning electrode wiring 102a and the scanning electrode wiring 102a. The scan electrode wiring 102b has the same wiring width. With these simple configurations, variations in display luminance among all display elements can be eliminated or suppressed. Details will be described later.

  The scan electrode connector unit 112 is connected to the scan electrode driving circuit 200 via a predetermined wiring. Specifically, a flexible printed wiring (FPC: Flexible Printed) having one end connected to the scan electrode driving circuit 200. The other end of Circuits is crimped. Similarly, the data electrode connector 113 is connected to the data electrode driving circuit 300 via a predetermined wiring. Specifically, the other end of the flexible printed wiring connected to the data electrode driving circuit 300 at one end is connected to the data electrode driving circuit 300. It is crimped.

  As described above, the display panel 100 has a multilayer structure. Specifically, the display panel 100 emits light by the glass substrate including the data electrode and the data electrode wiring and the substrate including the scanning electrode and the scanning electrode wiring. It is a structure in which layers (and a hole transport layer, etc.) are sandwiched and sealed (sealed). A well-known sealant (or adhesive) for bonding the two substrates is applied to the seal portion 104 indicated by a dotted line in FIG.

<1.3 Configuration of scan electrode wiring>
Next, the configuration of the scan electrode wiring will be described. The scanning electrode wirings 102a to 102d in the display panel 100 have a predetermined length and wiring width so that resistance values are substantially the same in order to eliminate or suppress variations in display luminance among all display elements. . Therefore, in order to calculate these resistance values, first, the current value I flowing through each scan electrode wiring is calculated.

  Here, for convenience of explanation, the resistance values of the data electrode and the data electrode wiring are ignored. The resistance value of ITO constituting these wirings is much smaller than the resistance value of the scanning electrode and the metal layer constituting the scanning electrode wiring (specifically, about several Ω), and the actual number of data electrodes is 96. In this case, the value of the current that flows when light is emitted from the entire surface is as small as I / 96. Therefore, even if the resistance value of ITO is ignored, there is no big problem. In addition, in order to simplify the explanation, the resistance value (specifically, about 0.1 to several Ω) of the portion extending from the contact portion 105 in the horizontal direction among the scan electrode wirings is also ignored. Since it is easy to further consider these resistance values with reference to the calculation process described below, it is actually possible to design with sufficient consideration of these resistance values.

In an organic EL element that is an electro-optic element, it is known that the relationship between the current flowing through the element and the applied voltage can be approximated exponentially, and the applied voltage is particularly in the range of several volts. It is known that if it can be approximated by a quadratic function. From this, when the light emission voltage value of the organic EL element is set to Vel, the current flowing through the scan electrode wiring (connected to the scan electrode) indicating the current flowing through all the light emitting organic EL elements connected to a certain scan electrode is shown. The value I can be expressed as the following formula (1).
I = a · Vel ^ 2 + b · Vel + c (1)
Note that a, b, and c are predetermined constants.

When the power supply voltage is Vdd, the voltage applied to the scan electrode wiring Vr can be expressed as the following equation (2).
Vr = Vdd−Vel (2)

Therefore, from the above equation (2), the current value I flowing through the scan electrode wiring can also be expressed as the following equation (3).
I = Vr / Rr = (Vdd−Vel) / Rr (3)

Here, the above equation (3) is substituted into the above equation (1), and the light emission voltage value Vel can be expressed as the following equation (4) from the solution of the quadratic equation.
Vel = [(− (b + 1 / Rr) + √ {(b + 1 / Rr) ^ 2−4 · a · (c−Vdd / Rr)}] / (2 · a) (4)

  From the above, when the above equation (4) is substituted into the above equation (3), the current value I flowing through the scan electrode wiring can be obtained.

  Next, based on the above result, the resistance value of each scan electrode wiring is calculated. Here, in order to show that the bent portions of the scanning electrode wirings 102a and 102b reflecting the characteristics of the present invention are indispensable for eliminating or suppressing the variation in display luminance in all display elements, The resistance value of each scan electrode wiring in the display device having only the scan electrode wiring having the shortest wiring length satisfying a predetermined design condition does not exist, which is a characteristic part in the present embodiment. calculate.

  Note that the shortest wiring length (wiring distance) that satisfies a predetermined design condition is not limited to the physical shortest distance, but a constraint condition based on a suitable layout relationship, wiring shape, etc. of all wiring. As a general rule, the shorter the wiring length is, such as the constraints based on the manufacturing process that forms the display, the constraints based on the shape of the display panel and its frame area, and the constraints based on the ease of design and the need for simplification The shortest wiring length after satisfying one or more of the constraint conditions conventionally required in the design rule regarding the wiring that is considered preferable (because resistance becomes small). Therefore, for example, as shown in FIG. 2, the scan electrode wirings 102 c and 102 d have a wiring distance longer than the physical shortest distance connecting the contact portion 105 and the scan electrode connector portion 112. This is because constraints such as the shape and ease of design are taken into consideration, so it can be said that the shortest wiring length that satisfies a predetermined design condition is provided. However, the scan electrode wirings 102a and 102b have a wiring distance longer than the shortest physical distance connecting the contact part 105 and the scan electrode connector part 112, and further restrictive conditions such as the shape of the frame region and ease of design. However, in light of the above-described preferred wiring design rule, the wiring distance is unnecessarily long, and the wiring distance (hereinafter referred to as “redundant wiring length ( Or a redundant wiring distance).

  FIG. 3 is a plan view schematically showing a wiring configuration of the display panel 100 including only the wirings having no redundant wiring distance. The display panel 100 shown in FIG. 3 has the same configuration as that of the display panel 100 shown in FIG. 2 except for the shape of the scan electrode wirings 102a and 102b provided therein. Reference numerals are assigned and detailed description is omitted.

  That is, unlike the scan electrode wirings 102a and 102b shown in FIG. 2, the scan electrode wirings 102a and 102b shown in FIG. 3 are the shortest that satisfy the predetermined design condition without being bent to have redundant wiring lengths. The contact part 105 and the scan electrode connector part 112 are connected by the wiring length.

Assuming the display panel 100 shown in FIG. 3, the constants a, b, and c in the above equation (1) are 0.0006, 0.0118, and 0.0546, respectively, and two adjacent light emitting element portions (pixels) The pixel pitch, which is the distance between the centers of the formation portions), is 300 [μm], the length of the scan electrode wiring 102 a is 2000 [μm], the length of the scan electrode wiring 102 b is 2300 [μm], and the scan electrode wiring The length of the scanning electrode wiring 102d is 2900 [μm], the length of the scanning electrode wiring 102d is 2900 [μm], and the horizontal length of the scanning electrode wiring excluding the space between the wirings (that is, approximately equivalent to the frame length in the horizontal direction). Length) is 42 [μm], the design minimum width of the scan electrode wiring is 10 [μm], and the power supply voltage Vdd is 13 V, the resistance value of the scan electrode wiring becomes as uniform as possible. The resistance of the scanning electrode lines corresponding to the respective sheet resistance value when variously changed the sheet resistance of the scanning electrode lines was calculated based on the above equation (3) and the above equation (4) sea urchin consideration. Since this calculation is easy, the calculation process is omitted and only the results are shown in the table below.

  As shown in the table above, the resistance values of the scan electrode wirings 102c and 102d are the same even when the sheet resistance value is changed variously, but the resistance values of the scan electrode wirings 102a and 102b are the same as those in the above design. Even if the sheet resistance value is variously changed due to the restriction on the minimum width, the sheet resistance values are not the same. Note that the width of the scan electrode wirings 102a and 102b obtained from the calculation result is 10 [μm], which is the minimum design width, and the width of the scan electrode wiring 102c is 10.4 [μm]. The width of 102d is 11.6 [μm].

According to the above results, in the configuration of the display panel shown in FIG. 3, since the wiring resistance of all the scanning electrode wirings is not the same, it seems that the luminance variation of all the display elements cannot be eliminated. In general, even when the wiring resistances of all the scanning electrode wirings are not the same, there are cases where the luminance variation of all the display elements can be eliminated. That is, when the luminance is in the range of 100 to 1000 [cd / m ² ], the change is visually recognized only when the luminance fluctuation amount is 2% or more (that is, the luminance change is recognized by human vision). Since the (required) luminance in a display device including a general organic EL element is about 100 [cd / m ² ], the variation in luminance, that is, an organic EL proportional to the luminance is required. If the fluctuation amount of the current flowing through the element is within 2%, the luminance variation cannot be visually recognized, and therefore the luminance variation of all the display elements can be eliminated. Therefore, how the difference in the sheet resistance value of the scan electrode wiring shown in the above table affects the current fluctuation amount will be considered.

  FIG. 4 is a diagram showing the relationship between the sheet resistance value in each scan electrode wiring and the fluctuation amount of the current flowing in the scan electrode wiring corresponding to the current flowing in the light emitting organic EL element. As shown in FIG. 4, the current fluctuation amount between the scan electrode wiring 102c and the scan electrode wiring 102d is the same as the two wiring resistances. The amount of current fluctuation is 0%. On the other hand, the current fluctuation amount between the scan electrode wiring 102a and the scan electrode wiring 102b increases as the sheet resistance value increases, and the sheet resistance value becomes 0.2 [Ω / □ (square). ] If it becomes the above value, it exceeds 2%. Similarly, the amount of current fluctuation between the scan electrode wiring 102b and the scan electrode wiring 102c increases as the sheet resistance increases, and the sheet resistance value becomes a value of 0.35 [Ω / □] or more. It will exceed 2%.

  From the above results, although there is some variation depending on the size of the pixel formation portion and the characteristics of the organic EL element, if the sheet resistance value is less than about 0.2 [Ω / □], the luminance variation is visible on the entire screen. However, if the sheet resistance value is 0.2 [Ω / □] or more, luminance variation is visually recognized in part (or all) of the screen.

  Therefore, the brightness variation is suppressed or eliminated by setting the sheet resistance value of the scan electrode wiring to less than 0.2 [Ω / □], and as close as possible to 0 [Ω / □]. However, in order to form a metal wiring with a sheet resistance value of less than 0.2 [Ω / □], it is necessary to use a very expensive metal as a material and satisfy strict process conditions. Cost increases. Therefore, the sheet resistance value of the scanning electrode wiring is preferably 0.2 [Ω / □] or more.

  Further, in order to suppress the luminance variation while setting the sheet resistance value of the scan electrode wiring to 0.2 [Ω / □] or more, the width of the scan electrode wiring is set to 10 [μm], which is the minimum width in the design. It is possible to make it smaller. For example, when the width of the scan electrode wiring 102a is 8 [μm] and the width of the scan electrode wiring 102b is 9.2 [μm], the resistance values of the scan electrode wirings 102a to 102d are as shown in the table above. Even when the values are changed variously, they can be made substantially the same. However, if the width of the scan electrode wiring is made smaller than the above design minimum width due to factors such as etching accuracy for forming the scan electrode wiring, the width of the formed scan electrode wiring is significantly different from the desired value. In the worst case, the scan electrode wiring may be disconnected. Therefore, the width of the scan electrode wiring is preferably 10 [μm] or more, which is the minimum width in design.

  Therefore, the variation in luminance is suppressed while the sheet resistance value of the scan electrode wiring is set to 0.2 [Ω / □] or more and the width of the scan electrode wiring is set to 10 [μm] or more which is the minimum width in the design. Therefore, the scan electrode wirings 102a and 102b have the redundant wiring length described above. Since the resistance value of the scan electrode wirings 102a and 102b is increased by the redundant wiring length, even if the width of the scan electrode wiring is 10 [μm], the resistance value of the scan electrode wirings 102c and 102d is changed to the scan electrode wiring as a result. The resistance values of 102a and 102b can be made substantially the same.

Specifically, while the width of the scan electrode wirings 102a and 102b is set to 10 [μm], the length of the scan electrode wiring 102a is changed from 2000 [μm] to 2500 [μm], thereby When the length of 102b is changed from 2300 [μm] to 2500 [μm], the resistance values of the scanning electrode wirings 102a to 102d are the same even if the sheet resistance value is variously changed as shown in the table below. Can be. In the case as shown in the table below, the fluctuation amount of the current flowing through the scan electrode wiring becomes 0%, so that the luminance variation can be completely eliminated.

  However, the current flowing through the scan electrode wiring is not sufficient for reducing the resistance value of each scan electrode wiring as much as possible or having a sufficient area on the substrate for routing the scan electrode wiring to have a redundant wiring length. Redundant wiring lengths shorter than the redundant wiring length necessary for setting the fluctuation amount of the current to 0% may be set for the scan electrode wirings 102a and 102b. Even in this case, if the redundant wiring length necessary for setting the fluctuation amount of the current flowing in the scanning electrode wiring to 2% or less is set in the scanning electrode wirings 102a and 102b, the luminance variation can be visually recognized. Therefore, variation in luminance can be sufficiently suppressed. Furthermore, this is a case where the redundant wiring length is set in the scan electrode wirings 102a and 102b so that the current fluctuation amount exceeds a predetermined fluctuation amount exceeding 2% (for example, 5%, 8%, 10%, etc.). However, since the luminance variation is less visible than when no redundant wiring portion is provided, the luminance variation can be suppressed to some extent.

  Here, the redundant wiring portion for routing the scanning electrode wirings 102a and 102b so as to have the redundant wiring length is formed in a conventional empty area existing in the direction from the data electrode wiring 103a to the scanning electrode wiring. This empty area is formed from the data electrode wiring 103a (FIG. 2) by the area where the contact portion 105 shown in FIG. 2 is formed or the dummy pixel area (not shown) formed between the area and the data electrode wiring 103a. This is caused by the formation of the scan electrode wirings separated (to the right in 2). It should be noted that any space other than this space may be used as long as the wiring can be formed, as long as the space unique to the various display panels is used.

  Further, it is preferable that the redundant wiring portion for routing the scanning electrode wirings 102a and 102b is formed so as to be bent (meander) in the vacant area and in the seal portion 104, more specifically. Is preferably formed uniformly in a specific portion within the region. If formed in this way, the sealant applied to the seal portion 104 spreads to a certain degree of thickness, and the adhesion at the seal portion 104 is improved. That is, conventionally, the redundant wiring has the above-described redundant wiring because the height of the vacant area from the substrate surface is different from the height of the area where the scanning electrode wiring and the data electrode wiring are formed. Since the height is made equal to some extent by forming the portion in the empty area, the adhesion is improved.

<2. Effect>
As described above, the display device according to the present embodiment exists in the direction from the data electrode wiring 103a to the scanning electrode wiring regardless of limitations (constraints) such as the size of the frame region and the design minimum value of the wiring width. With a simple configuration in which the scan electrode wirings 102a and 102b are routed so as to have a redundant wiring length in a conventional empty area, preferably, the amount of fluctuation of the current flowing through the scan electrode wiring is preferably 2% or less, so that all display Variations in display luminance in the element can be eliminated or suppressed.

<3. Modification>
The display device of the present embodiment is a constant voltage type control type display device, but even if it is a constant current type control type display device, the display luminance variation in all display elements is eliminated or suppressed by the same configuration. be able to. As described above, in the display device of the constant current type control system, when the wiring resistance varies, the waveform rounding (shape) of the pulse signal of the voltage applied to the organic EL element as the display element varies, and this causes the organic EL Since variation (unevenness) occurs in the change in the light emission luminance of the element, this can be eliminated or suppressed by the above configuration.

  The display device according to the present embodiment includes the scan electrode driving circuit 200 and the data electrode driving circuit 300 outside the display panel 100, but the scan electrode driving circuit 200 and the data electrode driving circuit 300 may be built in the display panel 100. Good. In this case, the display panel 100 itself becomes a display device. Further, even when the scan electrode driving circuit 200 and the data electrode driving circuit 300 are provided outside the display panel 100, the display panel 100 can be said to be a display device in a broad sense.

  The display device of the present embodiment has a configuration in which the scan electrode wirings 102a to 102d are connected to the left ends of the scan electrodes SL1 to SL4 shown in FIG. Scan electrodes SL1 and SL3 corresponding to, and scan electrodes SL2 and SL4 corresponding to even rows may be connected to scan electrode wirings corresponding to left and right alternately. With this configuration, it is possible to reduce variations in luminance of the organic EL elements in the left-right direction of the display screen caused by the resistances of the scan electrodes SL1 to SL4.

  The display device of this embodiment has a simple configuration in which the scan electrode wirings 102a and 102b are routed so as to have a redundant wiring length, but the scan electrode wirings 102c and 102d are routed so as to have a redundant wiring length. Configuration is also possible. If the scan electrode wirings 102a and 102b cannot be configured to have a sufficiently redundant wiring length, a known resistor or a predetermined (relatively high) is added to a predetermined part of the scan electrode wirings 102a and 102b in addition to this configuration. ) The wiring resistance value may be realized by interposing a substance having electrical resistance. With these configurations, it is possible to eliminate or suppress variations in display luminance in all display elements, preferably by setting the fluctuation amount of the current flowing through the scan electrode wiring to 2% or less.

It is a figure which shows simply the whole structure of the display apparatus which concerns on one Embodiment of this invention. It is a top view which shows simply the wiring structure of the display panel in the said one Embodiment. It is a top view which shows simply the wiring structure of the display panel provided only with the wiring which does not have the said redundant wiring distance in the said one Embodiment. It is a figure which shows the relationship between the sheet resistance value in each scanning electrode wiring in the said one Embodiment, and the variation | change_quantity of the electric current which flows into the scanning electrode wiring corresponded to the electric current which flows into the light-emitting organic EL element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Organic EL element 100 ... Display panel 102a-102d ... Scan electrode wiring 103a-103d ... Data electrode wiring 104 ... Seal part 105 ... Contact part 112 ... Scan electrode connector part 113 ... Data electrode connector part 200 ... Scan electrode drive circuit 300 ... Data electrode drive circuit 400 ... Constant voltage power supply SL1 to SL4 ... Scan electrode DL1 to DL4 ... Data electrode

Claims (6)

A matrix corresponding to scan electrodes that are a plurality of parallel electrodes extending in a predetermined direction, data electrodes that are a plurality of parallel electrodes extending in a direction orthogonal to the scan electrodes, and intersections of the scan electrodes and the data electrodes A plurality of electrodes arranged to form a plurality of pixels, scanning electrode driving means for selectively grounding the scanning electrodes for each predetermined period, and scanning electrode wiring for connecting the scanning electrodes, and the electro-optics A display device comprising a data electrode wiring for connecting the data electrode and a data electrode driving means for selectively flowing a current from a power supply for supplying a current to be supplied to the element to the data electrode,
Each of the scan electrode wirings has a wiring width and a wiring length that are equal to or larger than a predetermined width so as to have substantially the same resistance value, and has a predetermined width or a width in the vicinity of the predetermined width among the scanning electrode wirings. The display device, wherein the one or more scanning electrode wirings have a redundant wiring length.   The scan electrode wiring having the redundant wiring length is disposed so as to be bent in a predetermined region between the scan electrode wiring and the data electrode closest to the scan electrode wiring. Item 4. The display device according to Item 1.   The display device according to claim 1, wherein the scan electrode wiring has a sheet resistance value of 0.2Ω / □ or more.   4. The display device according to claim 1, wherein the predetermined width is a design minimum width for forming the scan electrode wiring. 5.   The display device according to claim 4, wherein the predetermined width is 10 μm.   The display device according to claim 1, wherein the electro-optic element is an organic electroluminescence element.

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