JP5454029B2 - Lighting device and electronic device - Google Patents

Description

  The present invention relates to a lighting device and an electronic apparatus.

  2. Description of the Related Art A front light that is an illumination device that is disposed on a display surface of a liquid crystal panel and illuminates the display surface is known. Generally, a front light is used in a reflective display panel. When there is enough external light, it turns off and becomes a transparent plate, transmits the front light in the transparent plate state, and is reflected by external light. There are many things that display. For this reason, it is often used in transmissive display panels, and it is said that power consumption can be reduced compared to a backlight that is lit regardless of the presence or absence of external light.

  For example, in Patent Document 1, an anode made of a transparent conductive material such as ITO (Indium Thin Oxide), an organic EL layer provided on the anode, A front light including an organic EL element having a cathode (reflective film) made of a metal such as aluminum provided on an EL layer as a light source is shown.

  FIG. 16 is an equivalent circuit diagram showing an electrical configuration of a conventional front light. The front light 501 has an anode wiring 503 connected to the anode of the DC power source 502 and a cathode wiring 504 connected to the cathode. The anode wiring 503 and the cathode wiring 504 are branched into a plurality, and a plurality of light emitting elements 505 that are connected in parallel and emit light by forward current are provided between the anode wiring 503a and the cathode wiring 504a. It has been.

JP 2007-17720 A

  However, since the conventional front light uses an organic EL element as a light source, there is a problem that it is difficult to ensure a sufficient life. Specifically, the organic EL material is still a developing material and has a problem that the luminance life is short.

  In addition, since the display surface is observed through the front light itself when it is turned on or off, the size of the organic EL element that has a reflective film (cathode) and serves as a light shielding portion is It was formed small (light emitting area) so as not to affect the above. For this reason, in order to obtain the desired luminance, a large current must be passed, which causes a problem that the temperature of the organic EL element rises and the organic EL element deteriorates. That is, there is a problem that it is difficult to suppress deterioration of the light emitting element.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A lighting device according to this application example includes a plurality of light emitting elements that emit light by a forward current flowing from a first terminal toward a second terminal, a direct current power source, and the direct current power source to the multiple light emitting elements. A first light-emitting element group comprising a plurality of light-emitting elements each including at least an anode wiring and a cathode wiring for supplying power, wherein the first terminal is connected to a first anode wiring branched from the anode wiring; and the anode wiring A second light emitting element group composed of a plurality of the light emitting elements in which the first terminal is connected to a second anode wiring branched from the first light emitting element group, the first light emitting element group, and the plurality of light emitting elements in the second light emitting element group A plurality of light emitting units each having a common cathode wiring branched from the cathode wiring and connected in common to the second terminal.

  According to this configuration, since the first light emitting element group and the second light emitting element group are connected to the common cathode wiring, a common cathode region can be formed. Therefore, it is possible to reduce the area of the cathode and to increase the area of the light transmission area other than the cathode area, as compared with the configuration in which each light emitting element group includes the cathode and the cathode common wiring. . As a result, the aperture ratio can be improved, and the amount of current for obtaining a necessary light amount can be reduced. As a result, the light emitting element can be prevented from generating heat, the light emitting element can be prevented from deteriorating, and the life can be extended.

  Application Example 2 In the illumination device according to the application example described above, it is preferable that the lighting device further includes a switch that exclusively switches a connection between the anode wiring and the first anode wiring or the second anode wiring.

  According to this configuration, it is possible to cause the first light emitting element group connected to the first anode wiring and the second light emitting element group connected to the second anode wiring to alternately emit light by using the switch. Therefore, for example, by continuously emitting light until the luminance of one light emitting element group decreases to the lower limit threshold luminance, and then switching to the other light emitting element group and continuously emitting light, only one is emitted. The light emission time can be extended as compared with the case where these light emitting element groups emit light continuously. As a result, the lifetime of the lighting device can be extended. In addition, when a failure occurs in one of the light emitting element groups, light can be emitted using the other light emitting element group.

  Application Example 3 In the illumination device according to the application example described above, it is preferable to include a detection unit that detects the luminance of the light emitting element or the voltage across the light emitting element.

  According to this configuration, since the luminance or voltage of the light emitting element is detected by the detection unit, for example, it is possible to emit light up to the luminance that is the lower limit threshold (can be prevented from being lower than the luminance that is the lower threshold). ). In addition, when used in combination with a switch, when the brightness is reduced to a lower threshold value, it is possible to switch between light emission by one light emitting element and light emission by the other light emitting element, which is higher than the lower threshold brightness. The brightness can be maintained for a long time.

  Application Example 4 In the illumination device according to the application example, the switch includes the anode wiring and the first anode wiring branched from the anode wiring or the first wiring according to the luminance or voltage detected by the detection unit. It is preferable to electrically connect the two anode wirings.

  According to this configuration, since electric power is applied to the first anode wiring or the second anode wiring according to the luminance or voltage, for example, one of the light emitting elements is caused to emit light until the luminance becomes the lower limit threshold, and then the other light emission is performed. The device can automatically switch to light emission. In addition, for example, when a certain luminance is reached, the light emission is switched to one of the light emitting elements, and when the certain luminance is further reached, the light emission is switched to one of the light emitting elements. it can.

  Application Example 5 In the illumination device according to the application example, the detection unit is an optical sensor.

  According to this configuration, since the luminance is detected by the optical sensor, when the luminance is reduced to a certain luminance, the luminance higher than a predetermined value can be maintained by switching from one light emitting element to the other light emitting element.

  Application Example 6 In the illumination device according to the application example described above, the illumination device includes a light emitting region in which the plurality of light emitting elements are arranged, a light emitting element for detection is further provided around the light emitting region, and the detection unit includes: It is preferable to detect the luminance of light emitted from the light emitting element for detection.

  According to this configuration, since the light-emitting element for detection is provided around the light-emitting area, the luminance of the light-emitting element can be detected without reducing the necessary luminance in the light-emitting area.

  Application Example 7 An illumination device according to this application example includes a transparent substrate, a plurality of transparent anode wiring and cathode wiring formed on the transparent substrate, a plurality of light emitting elements that emit light by forward current, The first anode wiring and the second anode wiring branched from the anode wiring are formed on both sides of the common cathode wiring branched from the cathode wiring, and extend from the first anode wiring to the common cathode wiring. A first light-emitting element group composed of a plurality of light-emitting elements that emit light by a forward current flowing; and a second light-emitting element composed of a plurality of light-emitting elements that emit light by a forward current flowing from the second anode wiring to the common cathode wiring. And a light emitting element group.

  According to this configuration, since the first light emitting element group and the second light emitting element group are provided on the transparent substrate using the common cathode wiring, a common cathode region can be formed in a plane. Therefore, compared to a configuration in which each light emitting element group uses separate cathode wirings, it is possible to reduce the area of the cathode, and it is possible to increase the area of a region where light other than the cathode region passes. As a result, the aperture ratio can be improved, and the amount of current for obtaining a necessary light amount can be reduced. As a result, the light emitting element can be prevented from generating heat, the light emitting element can be prevented from deteriorating, and the life can be extended.

  Application Example 8 In the illumination device according to the application example described above, the illumination device is a front light arranged on a display surface of a liquid crystal panel.

  According to this configuration, since the front light is disposed on the display surface of the liquid crystal panel, it is possible to supply light from the front light even when sufficient external light cannot be obtained in the reflective liquid crystal panel. , Display quality can be improved.

  Application Example 9 An electronic apparatus according to this application example includes the above-described illumination device.

  According to this configuration, deterioration of the light emitting element is suppressed, and a long-life electronic device can be provided.

FIG. 2 is a schematic cross-sectional view illustrating the structure of an organic EL device as a lighting device according to the first embodiment and a reflective liquid crystal device using the organic EL device as a front light. The expanded sectional view which expands and shows the A section of the organic electroluminescent apparatus shown in FIG. The equivalent circuit diagram which shows the electric constitution of the organic electroluminescent apparatus as an illuminating device. The schematic plan view which shows the structure of an organic electroluminescent apparatus. The model enlarged view which expands and shows the B section of the organic electroluminescent apparatus shown in FIG. FIG. 6 is a schematic cross-sectional view taken along the line CC ′ of the organic EL device shown in FIG. 5. The schematic cross section which shows the manufacturing method of an organic electroluminescent apparatus in order of a process. The schematic cross section which shows the manufacturing method of an organic electroluminescent apparatus in order of a process. The schematic cross section which shows the manufacturing method of an organic electroluminescent apparatus in order of a process. The schematic cross section which shows the manufacturing method of an organic electroluminescent apparatus in order of a process. The equivalent circuit diagram which shows the electric constitution of the organic electroluminescent apparatus as an illuminating device of 2nd Embodiment. The equivalent circuit diagram which shows the electric constitution of the organic electroluminescent apparatus as an illuminating device of 3rd Embodiment. FIG. 3 is a schematic diagram illustrating a mobile phone as an example of an electronic apparatus including an organic EL device. The equivalent circuit diagram which shows electrically the structure of the organic electroluminescent apparatus of the modification 1. FIG. The graph which shows the relationship between time and a brightness | luminance, and the relationship between time and a voltage. The equivalent circuit diagram which shows the electric constitution of the conventional frontlight.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. Note that the drawings to be used are appropriately enlarged or reduced so that the part to be described can be recognized.

(First embodiment)
<Configuration of Reflective Liquid Crystal Device Having Illumination Device>
FIG. 1 is a schematic cross-sectional view showing the structure of an organic EL device as a lighting device and a reflective liquid crystal device using the organic EL device as a front light. FIG. 2 is an enlarged cross-sectional view showing an A portion of the organic EL device shown in FIG. Hereinafter, the structures of the reflective liquid crystal device and the organic EL device will be described with reference to FIGS.

  The reflective liquid crystal device 10 is a device in which a reflective liquid crystal panel 11 and an organic EL device 12 as a lighting device (front light) disposed on the display surface of the liquid crystal panel 11 are combined. Specifically, the reflective liquid crystal device 10 reflects external light (light generated in an organic EL device 12 (front light) described later) irradiated from the viewer 14 side, and displays a color image to the viewer 14. Can be displayed.

  The reflective liquid crystal panel 11 includes an element substrate 15, a counter substrate 16, and a liquid crystal layer 17 sandwiched between the element substrate 15 and the counter substrate 16. On the liquid crystal layer 17 side (hereinafter referred to as “upper layer” or “upper layer”) of the element substrate 15, TFTs (Thin Film Transistors) 18 and pixel electrodes 19 corresponding to the respective TFTs 18 are regularly formed. Yes.

  A first alignment film 21 is formed on the pixel electrode 19. The liquid crystal layer 17 is sandwiched between a first alignment film 21 and a second alignment film 22 described later. In addition, since it is the reflective liquid crystal panel 11, the element substrate 15 does not require transparency. Therefore, a substrate made of an opaque material such as plastic can be used.

  The pixel electrode 19 has reflectivity, and reflects light irradiated from the liquid crystal layer 17 side as reflected light R in the direction of the liquid crystal layer 17. Such reflection may be achieved by forming the pixel electrode 19 itself from a reflective material, or combining the pixel electrode 19 formed from a transparent conductive material such as ITO and a reflective layer made of aluminum or the like. Also good.

  The TFT 18 and the pixel electrode 19 are separated by an interlayer insulating layer 23 and are electrically connected via a contact hole. The TFT 18 is controlled by a peripheral circuit (not shown), and an arbitrary voltage can be applied to the corresponding pixel electrode 19.

  The counter substrate 16 is a substrate made of a transparent material such as glass. The counter substrate 16 is arranged so as to be parallel to the element substrate 15 via a sealing material (not shown), that is, at equal intervals throughout the entire area. On the surface of the counter substrate 16 on the liquid crystal layer 17 side, the color filter layer 24, the counter electrode 25, and the second alignment film 22 are sequentially arranged from the counter substrate 16 side. A polarizing plate 26 is disposed on the surface of the counter substrate 16 opposite to the liquid crystal layer 17 side.

  The color filter layer 24 includes a color filter 24a corresponding to the pixel electrode 19 in plan view, and a light shielding layer (black matrix) 24b formed between adjacent color filters 24a. The color filter layer 24 of the present embodiment includes a red color filter, a green color filter, and a blue color filter. The counter electrode 25 is made of a transparent conductive material such as ITO.

  The reflective liquid crystal device 10 having such a configuration can irradiate the liquid crystal panel 11 with sufficient light because the organic EL device 12 (front light) is disposed on the display surface of the liquid crystal panel 11. Note that the front light is formed so that the area of the light emitting element is small so as not to affect the display (because the light emitting element has a reflective film). For this reason, it is necessary to flow a large current in order to obtain a predetermined luminance. Hereinafter, the structure of such an illumination device (front light: organic EL device 12) will be briefly described.

  As shown in FIGS. 1 and 2, the organic EL device 12 as an illumination device has a configuration in which a plurality of light emitting elements 31 are arranged on the surface of a transparent substrate 32. More specifically, the organic EL device 12 includes a transparent substrate 32, a light emitting element 31 provided on the upper layer (observer 14 side) of the transparent substrate 32, and a sealing structure 33 provided above the light emitting element 31. I have.

  Specifically, as shown in FIG. 2, the light emitting element 31 includes an anode 35, a light emitting functional layer 36 provided on the anode 35, and a cathode 37 provided on the light emitting functional layer 36. The cathode 37 is made of a material having reflective conductivity such as aluminum (Al). Specifically, the EL light L generated in the light emitting functional layer 36 is irradiated in the direction of the liquid crystal panel 11 due to the reflectivity of the cathode 37. Then, the EL light L is reflected by the individual pixel electrodes 19 to form an image for the observer 14. Note that the region shown in FIG. 2 is a light emitting region, and a transmissive region that transmits the reflected light R is provided around it.

  The light emitting functional layer 36 includes a hole injection layer 41, a hole transport layer 42, a light emitting layer 43, an electron transport layer 44, and an electron injection layer 45 in order from the anode 35 side. .

  The hole injection layer 41 has a function of improving the hole injection efficiency from the anode 35. The hole transport layer 42 has a function of transporting holes injected from the anode 35 through the hole injection layer 41 to the light emitting layer 43.

  The light emitting layer 43 is a layer of an organic light emitting material that exhibits an electroluminescence phenomenon. By applying a voltage between the anode 35 and the cathode 37, holes are injected into the light emitting layer 43 from the hole transport layer 42 and electrons are injected from the electron transport layer 44. Light emission occurs when recombined. In the present embodiment, white light is emitted.

  The electron transport layer 44 has a function of transporting electrons injected from the cathode 37 through the electron injection layer 45 to the light emitting layer 43. The electron injection layer 45 has a function of improving the electron injection efficiency from the cathode 37.

  A light interference layer 48 including a cathode 37, a transparent layer 46, and a transflective layer 47 is provided between the light emitting functional layer 36 and the sealing structure 33. The transparent layer 46 is made of, for example, lithium fluoride (LiF). The transflective layer 47 is made of, for example, aluminum (Al). By this optical interference layer 48, for example, reflected light reflected by outside light is reduced.

  The reflectivity of the cathode 37 described above is also exerted on ambient light, that is, light irradiated from the viewer 14 side other than the EL light L. When there is ambient light, the reflected light from the cathode 37 (reflected light other than the reflected light R from the pixel electrode 19) is irradiated to the observer 14 side as light different from the light forming the image. In the present embodiment, since the light interference layer 48 is provided on the viewer 14 side of the light emitting element 31, reflected light from outside (reflected light other than the reflected light R) is reduced.

  The sealing structure 33 is provided to protect the light emitting element 31 by suppressing entry of moisture and the like from the outside. Examples of the material of the sealing structure 33 include water-resistant materials such as a silicon oxynitride film (SiON) and a silicon nitride film (SiN). Further, as the sealing structure 33, a resin material may be used, and a glass substrate or the like may be bonded to the outermost surface.

<Configuration of lighting device>
FIG. 3 is an equivalent circuit diagram showing an electrical configuration of an organic EL device as a lighting device. Hereinafter, the configuration of the organic EL device will be described with reference to FIG.

  As shown in FIG. 3, the organic EL device 12 uses a DC power source 50 that supplies DC power as a power source. The organic EL device 12 includes an anode wiring 51 connected to the anode of the DC power supply 50 and a cathode wiring 52 connected to the cathode of the DC power supply 50. The anode wiring 51 is branched into a first anode wiring 51a and a second anode wiring 51b. The cathode wiring 52 is branched into a plurality of cathode wirings 52 (common cathode wiring).

  Between the first anode wiring 51a and the cathode wiring 52, there are provided a plurality of first light emitting elements 31a that are connected in parallel and emit light by forward current. In addition, these 1st light emitting elements 31a are called 1st light emitting element group 31a '. A plurality of second light emitting elements 31b that are connected in parallel and emit light by forward current are provided between the second anode wiring 51b and the cathode wiring 52. The second light emitting elements 31b are referred to as a second light emitting element group 31b '. Further, the first light emitting element group 31a 'and the second light emitting element group 31b' are referred to as light emitting units. The first light emitting element 31a and the second light emitting element 31b can be equivalently regarded as diodes.

  Specifically, in the plurality of first light emitting elements 31a connected in parallel, the anode 35 (anode: first terminal) is connected to the first anode wiring 51a, and the cathode 37 (cathode: second terminal) is connected to the cathode wiring 52. The light emitting functional layer 36 is provided between the anode 35 and the cathode 37. In the plurality of second light emitting elements 31 b connected in parallel, the anode 35 (anode) is connected to the second anode wiring 51 b, the cathode 37 (cathode) is connected to the cathode wiring 52, and between the anode 35 and the cathode 37. The light emitting functional layer 36 is provided.

  The first light emitting element group 31 a ′ and the second light emitting element group 31 b ′ are alternately arranged in the light emitting region 53. Thus, the first light emitting element group 31 a ′ and the second light emitting element group 31 b ′ are connected by the two anode wirings 51 a and 51 b and the one cathode wiring 52. That is, the cathode wiring 52 is used in common with the first light emitting element group 31a 'and the second light emitting element group 31b'.

  Next, the operation of the organic EL device 12 will be described with reference to FIG. First, when the DC power supply 50 is turned on, power (positive power) is supplied from the DC power supply 50 to the anode wiring 51, and forward connection is made via the first anode wiring 51a and the second anode wiring 51b. The first light emitting element 31a and the second light emitting element 31b emit light. The first light emitting element 31 a and the second light emitting element 31 b emit light with a luminance corresponding to the amount of current flowing through the light emitting functional layer 36.

  FIG. 4 is a schematic plan view showing the structure of the organic EL device. FIG. 5 is a schematic enlarged view showing the portion B of the organic EL device shown in FIG. 4 in an enlarged manner. FIG. 6 is a schematic cross-sectional view taken along the line CC ′ of the organic EL device shown in FIG. In FIG. 5, the illustration of the optical interference layer, the sealing structure, and the like is omitted. Hereinafter, the structure of the organic EL device will be described with reference to FIGS.

  As shown in FIG. 4, the organic EL device 12 includes a light emitting region 53 in which the light emitting elements 31 are regularly arranged with a predetermined interval, and a peripheral region 54 that is a region around the light emitting region 53. Yes.

  The light emitting region 53 is a region that irradiates the liquid crystal panel 11 with the EL light L, and corresponds to a region where an image is formed on the liquid crystal panel 11. In the light emitting region 53, a strip-shaped anode wiring 51 and a strip-shaped cathode wiring 52 are arranged substantially in parallel.

  Specifically, the first anode wiring 51a and the second anode wiring 51b are arranged on both sides of the commonly used cathode wiring 52. Both the anode wiring 51 and the cathode wiring 52 are made of ITO, which is a transparent conductive material, and do not affect the visibility of the image formed on the liquid crystal panel 11.

  As shown in FIGS. 5 and 6, the light emitting element 31 includes a first light emitting element 31a in which a light emitting functional layer 36a is formed in a region overlapping the first anode wiring 51a in plan view, and a second anode wiring 51b in plan view. And a second light emitting element 31b in which a light emitting functional layer 36b is formed.

  The light emitting element 31 includes a first light emitting element 31a and a second light emitting element 31b that form a pair, a first direction in which the first anode wiring 51a, the second anode wiring 51b, and the cathode wiring 52 extend, and a first A plurality are provided in a second direction orthogonal to the direction (see FIG. 4). In other words, the pair of first light emitting elements 31 a and second light emitting elements 31 b are provided in a matrix in the light emitting region 53.

  More specifically, in the first light emitting element 31a, an island-shaped (pad-shaped) light emitting functional layer 36a is provided on a part of the first anode wiring 51a on the transparent substrate 32 in plan view. An insulating film 55 is provided around the light emitting functional layer 36a. On the other hand, in the second light emitting element 31b, an island-shaped (pad-shaped) light emitting functional layer 36b is provided in a part on the second anode wiring 51b on the transparent substrate 32 in a plan view. An insulating film 55 is provided around the light emitting functional layer 36b.

  As shown in FIG. 6, a cathode 37 made of aluminum (Al) or the like electrically connected to the cathode wiring 52 is provided in a region extending from the light emitting functional layer 36a to the light emitting functional layer 36b. . The first anode wiring 51a, the cathode wiring 52, and the second anode wiring 51b are electrically insulated by an insulating film 55. Thus, the cathode 37 (cathode wiring 52) is commonly used for the pair of the first light emitting element 31a and the second light emitting element 31b.

  In such a configuration, the anode wiring 51 (the first anode wiring 51a and the second anode wiring 51b) is connected to the positive pole of the DC power supply 50, and the cathode wiring 52 is connected to the negative pole of the DC power supply 50. When the DC power supply 50 is turned on, power (positive power) is supplied from the DC power supply 50 to the anode wiring 51, and from the anode wiring 51 (first anode wiring 51a, second anode wiring 51b) side to the cathode wiring 52 side. Current flows. Then, the first light emitting element 31a and the second light emitting element 31b connected in the forward direction emit light.

  As described above, in the first light emitting element 31a and the second light emitting element 31b, the area of the portion that contacts the cathode wiring 52 from the cathode 37 is shared (common area 37a). Compared with the conventional configuration in which the two light emitting elements 31 b use separate cathode wirings 52, the area of the cathode 37 occupying the light emitting area 53 can be reduced. As a result, the aperture ratio can be improved, and the amount of current for obtaining a necessary light amount can be reduced. Therefore, it can suppress that the light emitting element 31 becomes high temperature, and can suppress that the light emitting element 31 deteriorates. As a result, the lifetime of the organic EL device 12 (front light) can be extended.

  In the organic EL device 12 as shown in FIG. 4, the light emitting region 53 is rectangular, and the light emitting elements 31 are regularly arranged in the light emitting region 53. However, the present invention is not limited to this mode. The light emitting region 53 may have a circular shape (including an indeterminate shape) or the like, and the arrangement of the light emitting elements 31 may be random. Hereinafter, a manufacturing method of the above-described organic EL device 12 will be described.

  7 to 10 are schematic cross-sectional views illustrating the method of manufacturing the organic EL device in the order of steps. If it explains in full detail, it is a schematic cross section which shows the manufacturing method centering on the 1st light emitting element and 2nd light emitting element which comprise an organic EL apparatus in order of a process. Hereinafter, a method for manufacturing an organic EL device (first light emitting element, second light emitting element) will be described with reference to FIGS.

  First, as shown in FIG. 7, the first anode wiring 51a, the cathode wiring 52, and the second anode wiring 51b are formed on the transparent substrate 32. Examples of the transparent substrate 32 include a glass substrate. In the first light emitting element 31a, the first anode wiring 51a is used as the anode 35. On the other hand, in the second light emitting element 31b, the second anode wiring 51b is used as the anode 35.

  The cathode wiring 52 is used for connection to the cathode 37 (see FIG. 6). The first anode wiring 51a, the second anode wiring 51b, and the cathode wiring 52 are made of a metal oxide conductive film having optical transparency such as ITO. Further, the first anode wiring 51a, the second anode wiring 51b, the cathode wiring 52, and each layer described below can be sequentially formed using, for example, a known vacuum deposition method.

  Next, as shown in FIG. 8, on the transparent substrate 32 and on the wiring (the first anode wiring 51a, the second anode wiring 51b, and the cathode wiring 52) so that the regions of the light emitting section 56 and the contact section 57 are opened. An insulating film 55 is formed in a part of the region. The insulating film 55 is formed of, for example, an acrylic resin or a polyimide resin.

  Next, as shown in FIG. 9, the light emitting functional layers 36a and 36b are formed. More specifically, a part on the first anode wiring 51a and the insulating film 55 on the first light emitting element 31a side, a part on the second anode wiring 51b and the insulating film 55 on the second light emitting element 31b side, The light emitting functional layers 36a and 36b are formed. As described above, the light emitting functional layers 36a and 36b are formed by sequentially stacking the hole injection layer 41, the hole transport layer 42, the light emitting layer 43, the electron transport layer 44, and the electron injection layer 45 (in FIG. 9, one layer). ).

  Next, as shown in FIG. 10, a cathode 37 is formed. Specifically, the cathode 37 is formed over the light emitting functional layers 36 a and 36 b, the cathode wiring 52, and the insulating film 55.

  By forming in this way, the cathode wiring 52 can be used in common in the pair of first light emitting element 31a and second light emitting element 31b. In addition, since the first anode wiring 51a, the second anode wiring 51b, the cathode wiring 52, and other layers can be formed in the same process, it is possible to reduce the number of processes, and the first has no difference in polarity. The light emitting element 31a and the second light emitting element 31b can be formed.

  As described above in detail, according to the first embodiment, the following effects can be obtained.

  (1) According to the first embodiment, the first light emitting element 31a and the second light emitting element 31b are connected to the cathode wiring 52 via the common contact portion 57 (see FIG. 8), so that they are used in common. A possible region (common region 37a) can be created. Therefore, the area of the cathode 37 can be reduced, and the area of the region (opening) through which the reflected light R other than the region of the cathode 37 can be increased. As a result, the aperture ratio can be improved, and the amount of current for obtaining a necessary light amount can be reduced. As a result, the light emitting elements 31a and 31b can be prevented from generating heat, the light emitting elements 31a and 31b can be prevented from deteriorating, and the life can be extended.

  (2) According to the first embodiment, the first light emitting element 31a and the second light emitting element 31b can be formed only by changing the vapor deposition range, such as when the film is formed by vapor deposition. Can be manufactured relatively easily.

(Second Embodiment)
<Configuration of lighting device>
FIG. 11 is an equivalent circuit diagram showing an electrical configuration of the organic EL device as the illumination device of the second embodiment. Hereinafter, the configuration of the organic EL device will be described with reference to FIG.

  In the organic EL device 112 according to the second embodiment, a current is passed through the first light emitting element group 31a ′ or the second light emitting element group 31b ′ using the switch 61 to alternately (or one of the light emitting element groups has a lifetime). When it reaches, it is different from the first embodiment in that light is emitted by switching to the other light emitting element group. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified here.

  As shown in FIG. 11, the organic EL device 112 according to the second embodiment includes an anode wiring 51 connected to one of the DC power supplies 50 and a cathode wiring 52 connected to the other of the DC power supplies 50. The anode wiring 51 is branched into a first anode wiring 151a and a second anode wiring 151b. A switch 61 is provided between the anode wiring 51, the first anode wiring 151a, and the second anode wiring 151b for passing a current through either the first anode wiring 151a or the second anode wiring 151b.

  As in the first embodiment, a plurality of first light emitting elements 31a that are connected in parallel and emit light by forward current are provided between the first anode wiring 151a and the cathode wiring 52. On the other hand, between the second anode wiring 151b and the cathode wiring 52, there are provided a plurality of second light emitting elements 31b that are connected in parallel and emit light by a forward current.

  Specifically, in the organic EL device 112 of the second embodiment, when the DC power supply 50 is turned on, a current flows through both the first anode wiring 51a and the second anode wiring 51b as in the first embodiment. Unlike the above, a current flows through only one of the first anode wiring 151a and the second anode wiring 151b. Therefore, the first light emitting element group 31 a ′ and the second light emitting element group 31 b ′ emit light alternately by switching the switch 61. As a preferred example of the switch 61, an analog switch having two circuits and one contact can be used.

  As in the first embodiment, the first light emitting element group 31 a ′ and the second light emitting element group 31 b ′ are connected by two anode wirings 151 a and 151 b and one cathode wiring 52. That is, the cathode wiring 52 is commonly used in the first light emitting element group 31a 'and the second light emitting element group 31b'.

  Thus, since the cathode 37 of the first light emitting element 31a and the cathode 37 of the second light emitting element 31b are connected to the cathode wiring 52 via the common contact portion 57 (see FIG. 8), the common cathode 37 areas (common area 37a) can be created. Therefore, the area of the cathode 37 in the light emitting region 53 can be reduced, and the area through which the reflected light R passes can be increased. As a result, the aperture ratio can be improved, and the amount of current for obtaining a necessary light amount can be reduced. As a result, the light emitting element 31 can be prevented from becoming high temperature, and the light emitting element 31 can be prevented from deteriorating.

  As described above in detail, according to the second embodiment, in addition to the effects (1) and (2) of the first embodiment described above, the following effects can be obtained.

  (3) According to the second embodiment, the switch 61 is used to connect the first light emitting element 31a connected to the first anode wiring 151a and the second light emitting element 31b connected to the second anode wiring 151b. Since it is possible to emit light alternately, for example, light is continuously emitted until the luminance of one light emitting element (for example, the first light emitting element 31a) decreases to the lower limit threshold luminance, and then the other light emitting element. By switching to (for example, the second light emitting element 31b) and continuously emitting light, the light emission time can be extended as compared with the case where only one light emitting element emits light continuously. As a result, the lifetime of the lighting device (organic EL device 112) can be extended. In addition, when a malfunction (abnormality) occurs in one of the light emitting elements, the other light emitting element can be used to emit light.

  (4) According to the second embodiment, the first light emitting element group 31a ′ and the second light emitting element group 31b ′ can be caused to emit light alternately, so that one of the light emitting element groups emits light. Since the other light emitting element group does not emit light, the other light emitting element group can be cooled. As a result, the light emitting elements 31a and 31b are prevented from deteriorating due to a high temperature, and the luminance is reduced as compared with the case where one light emitting element is continuously made to emit light (the display quality is reduced). (Deteriorating) time can be extended, and the service life can be improved.

(Third embodiment)
<Configuration of lighting device>
FIG. 12 is an equivalent circuit diagram showing an electrical configuration of the organic EL device as the illumination device of the third embodiment. Hereinafter, the configuration of the organic EL device will be described with reference to FIG.

  The organic EL device 212 of the third embodiment is provided with a detection light emitting element 131 and a detection unit (light sensor 211) for detecting the luminance of the first light emitting element 31a and the second light emitting element 31b. Different from one embodiment. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified here.

  As shown in FIG. 12, the organic EL device 212 of the third embodiment includes an anode wiring 51 connected to one of the DC power supplies 50 and a cathode connected to the other of the DC power supplies 50, as in the second embodiment. Wiring 52. The anode wiring 51 can be electrically connected to the first anode wiring 151a and the second anode wiring 151b via the switch 61, and the direction of the flowing current can be switched.

  In such an organic EL device 212, a characteristic part of the third embodiment is that a light emitting element for detection 131 (131a, 131b) used for detecting luminance between the anode wirings 151a, 151b and the cathode wiring 52. Is provided. Specifically, the detection light emitting element 131 emits light when a current flows to the first anode wiring 151b and a first detection light emitting element 131a that emits light when the current flows to the first anode wiring 151a side. And a second light emitting element for detection 131b. That is, when the first light emitting element 31a provided in the light emitting region 53 is caused to emit light, the first detecting light emitting element 131a also emits light simultaneously. On the other hand, when the second light emitting element 31b provided in the light emitting region 53 is caused to emit light, the second detection light emitting element 131b also emits light simultaneously.

  An optical sensor 211 is provided as a detection unit that detects luminance adjacent to the two detection light emitting elements 131 (131a and 131b). As the optical sensor 211, for example, a photodiode, a phototransistor, CSD, or the like can be used. Thus, by detecting the luminance through the detection light emitting element 131, the luminance of the first light emitting element 31a and the second light emitting element 31b in the light emitting region 53 can be detected. Then, the connection state of the switch 61 is switched in accordance with the detection result of the luminance by the optical sensor 211 (for example, when the luminance decreases and reaches the lower limit threshold value).

  Specifically, the operation when the anode wiring 51 is electrically connected to the first anode wiring 151a will be described first. When the DC power supply 50 is turned on, a current flows to the first anode wiring 151a side, the first light emitting element group 31a 'emits light, and the first detecting light emitting element 131a emits light. At this time, the light sensor 211 detects the luminance of the first detection light emitting element 131a. When the luminance reaches the lower limit threshold value (when the luminance decreases to a predetermined luminance), for example, the light emission of the first light emitting element group 31a 'is switched to the light emission of the second light emitting element group 31b'.

  Next, an operation when the anode wiring 51 is electrically connected to the second anode wiring 151b will be described. When the DC power supply 50 is turned on, a current flows to the second anode wiring 151b side, the second light emitting element group 31b 'emits light and the second detecting light emitting element 131b emits light. At this time, the luminance of the second detection light emitting element 131b is detected by the optical sensor 211. When the luminance reaches the lower limit threshold value, for example, the new organic EL device 212 is replaced.

  Note that a switching mechanism 213 that switches the connection state of the switch 61 in accordance with the detection value of the optical sensor 211 is preferably provided. Specifically, the optical sensor 211 and the switch 61 are provided so as to be linked via the switching mechanism 213.

  More specifically, first, the first light emitting element group 31a 'is caused to emit light. When it is determined by the optical sensor 211 that the luminance of the first detection light emitting element 131a has decreased to the luminance that is the lower limit threshold, the connection state of the switch 61 is changed by sending a signal to the switching mechanism 213, and the first The light emission of the light emitting element group 31a ′ is switched to the light emission of the second light emitting element group 31b ′. Thereby, it can switch automatically further, without a brightness | luminance falling from the threshold value of a minimum.

  Further, the detection light emitting element 131 is preferably provided in the peripheral region 54 outside the light emitting region 53 of the organic EL device 212. Since the optical sensor 211 is not disposed in the light emitting region 53, the luminance can be detected without reducing the luminance necessary for the light emitting region 53. Further, since the first detection light-emitting element 131a and the second detection light-emitting element 131b corresponding to the two light-emitting elements 31 (31a and 31b) are provided in the peripheral region 54, the two light-emitting states should be confirmed. Thus, it can be determined which light emitting element 31 (31a, 31b) is emitting light.

  As described above in detail, according to the third embodiment, in addition to the effects (1) to (4) of the above-described embodiment, the following effects can be obtained.

  (5) According to the third embodiment, since the optical sensor 211 is provided, the luminance of the first light emitting element 31a and the second light emitting element 31b can be confirmed. Therefore, it is possible to accurately switch from one light emitting element to the other light emitting element as compared with the method of switching the light emitting element by judging the luminance visually. Furthermore, since the luminance is detected by the optical sensor 211, it is possible to always emit light with a luminance higher than the lower limit threshold of luminance.

  (6) According to the third embodiment, since the switching mechanism 213 is provided, the connection state of the switch 61 can be automatically switched based on the detection result by the optical sensor 211. Thereby, for example, one light emitting element can be made to emit light until the luminance becomes a lower limit threshold, and then the other light emitting element can be automatically switched to emit light.

  (7) According to the third embodiment, since the detection light emitting elements 131 a and 131 b are provided in the peripheral region 54 around the light emitting region 53, the light emitting region 53 emits light without reducing necessary luminance. The luminance of the elements 31a and 31b can be detected.

(Fourth embodiment)
<Configuration of electronic equipment>
FIG. 13 is a schematic diagram illustrating a mobile phone as an example of an electronic apparatus including the above-described organic EL device. Hereinafter, the configuration of the mobile phone including the organic EL device will be described with reference to FIG.

  As shown in FIG. 13, the mobile phone 71 has a display unit 72 and operation buttons 73. The display unit 72 can perform high-quality display, such as improving the light emission time by the organic EL devices 12, 112, and 212 incorporated therein. The organic EL devices 12, 112, and 212 are used for various electronic devices such as mobile computers, digital cameras, digital video cameras, in-vehicle devices, audio devices, exposure devices, and lighting devices in addition to the cellular phone 71. it can.

  As described above in detail, according to the fourth embodiment, the following effects can be obtained.

  (8) According to the fourth embodiment, deterioration of the light emitting elements 31a and 31b is suppressed, and a long-life electronic device can be provided.

  In addition, embodiment is not limited above, It can also implement with the following forms.

(Modification 1)
As in the third embodiment described above, the present invention is not limited to detecting the luminance of the first light emitting element 31a or the second light emitting element 31b using the optical sensor 211. For example, as shown in FIG. The luminance may be obtained. FIG. 14 is an equivalent circuit diagram electrically showing the configuration of the organic EL device 312 of the first modification. FIG. 15A is a graph showing the relationship between time and luminance. FIG. 15B is a graph showing the relationship between time and voltage.

  First, as shown in FIG. 15A, when the light emitting element 31 is driven at a constant current density, the luminance of the light emitting element 31 decreases with time. Further, as shown in FIG. 15B, when the luminance decreases, the voltage increases with time.

  Using such characteristics, as shown in FIG. 14, a voltmeter 311 as a detection unit disposed between the anode wiring 51 (151a, 151b) and the cathode wiring 52 has a lower limit threshold of luminance. When the voltage value is detected (decrease to the threshold brightness), the switch 61 is switched to change the light emission of the first light emitting element group 31a ′ to the light emission of the second light emitting element group 31b ′, for example. The switch 61 may be switched manually or may be switched automatically using the switching mechanism 213 (see FIG. 12). According to this, the predetermined luminance can be maintained without lowering the luminance below the lower limit threshold. In addition, light can be emitted over a longer time than when light is emitted from only one light emitting element group. Further, the luminance can be determined by the driving voltage without directly detecting light.

(Modification 2)
As described in the second embodiment, the third embodiment, and the first modification, the first light emitting element 31a continuously emits light until the luminance decreases to a certain lower threshold value, and then the second light emitting element 31b. Instead of switching to, and continuously emitting light, the following may be performed. For example, the luminance of one light emitting element (for example, the first light emitting element 31a) and the other light emitting element (for example, the second light emitting element 31b) may be decreased stepwise. Specifically, using the optical sensor 211 or the voltmeter 311, when the luminance of one light emitting element is reduced to a predetermined luminance, the light emission of the other light emitting element is switched to lower the predetermined luminance. After that, the light emitting element is switched to one of the light emitting elements to emit light to a lower luminance. This is repeated step by step until the lower limit threshold of luminance is reached. According to this, since the luminance gradually decreases step by step, it is possible to suppress a sudden change in characteristics.

(Modification 3)
As described above, the first light emitting element 31a and the second light emitting element 31b are not limited to emitting white light. For example, the first light emitting element 31a emits red light by coating different light emitting layers. The second light emitting element 31b may emit green light. According to this, red illumination or green illumination can be created by changing the wiring of the current to flow. Further, for example, red illumination and green illumination may be used as field sequential drive. In this case, it is preferable to add green illumination.

(Modification 4)
As described above, the organic EL devices 12, 112, 212, and 312 are not limited to the bottom emission type, and may be applied as a top emission type.

(Modification 5)
As described above, the illumination device is not limited to being used as a front light of a liquid crystal display device, and may be used as general illumination, for example.

  DESCRIPTION OF SYMBOLS 10 ... Reflective type liquid crystal device, 11 ... Liquid crystal panel, 12, 112, 212, 312 ... Organic EL device as an illuminating device (front light), 14 ... Observer, 15 ... Element substrate, 16 ... Opposite substrate, 17 ... Liquid crystal Layer, 18 ... TFT, 19 ... pixel electrode, 21 ... first alignment film, 22 ... second alignment film, 23 ... interlayer insulating layer, 24 ... color filter layer, 24a ... color filter, 24b ... light shielding layer, 25 ... opposite Electrode, 26 ... Polarizing plate, 31 ... Light emitting element, 31a ... First light emitting element, 31b ... Second light emitting element, 32 ... Transparent substrate, 33 ... Sealing structure, 35 ... Anode, 36, 36a, 36b ... Light emitting functional layer 37 ... cathode, 37a ... common region, 41 ... hole injection layer, 42 ... hole transport layer, 43 ... light emitting layer, 44 ... electron transport layer, 45 ... electron injection layer, 46 ... transparent layer, 47 ... half Transmitting / reflecting layer, 48 ... light interference layer, DESCRIPTION OF SYMBOLS 0 ... DC power supply, 51 ... Anode wiring, 51a, 151a ... 1st anode wiring, 51b, 151b ... 2nd anode wiring, 52 ... Cathode wiring, 53 ... Light-emitting region, 54 ... Peripheral region, 55 ... Insulating film, 56 ... Light emitting part, 57 ... Contact part, 61 ... Switch, 71 ... Mobile phone, 72 ... Display part, 73 ... Operation button, 131 ... Light emitting element for detection, 131a ... Light emitting element for first detection, 131b ... Light emission for second detection Elements 211... Optical sensors as detection units, 213... Switching mechanism, 311.

Claims (7)

A plurality of light emitting elements that emit light by forward current flowing from the first terminal toward the second terminal;
DC power supply,
An anode wiring and a cathode wiring for supplying power to the plurality of light emitting elements from the DC power source;
A detection unit for detecting the luminance of the light emitting element or the voltage across the light emitting element ; and
The plurality of light emitting elements include a first light emitting element group including a plurality of light emitting elements in which the first terminal is connected to a first anode wiring branched from the anode wiring, and a second anode wiring branched from the anode wiring. A second light emitting element group including a plurality of light emitting elements connected to the first terminal ,
A plurality of light emitting units each including a common cathode wiring branched from the cathode wiring and connected in common to the second terminals of the plurality of light emitting elements in the first light emitting element group and the second light emitting element group ;
The switch electrically connects the anode wiring and the first anode wiring or the second anode wiring branched from the anode wiring according to the luminance or voltage detected by the detection unit. Lighting device. The lighting device according to claim 1,
The lighting device further comprising a switch that exclusively switches a connection between the anode wiring and the first anode wiring or the second anode wiring. The lighting device according to claim 1 or 2 ,
The illumination device according to claim 1, wherein the detection unit is an optical sensor. It is an illuminating device as described in any one of Claim 1 thru | or 3 , Comprising:
A light emitting region in which the plurality of light emitting elements are disposed;
A light emitting element for detection is further provided around the light emitting region,
The illuminating device, wherein the detection unit detects a luminance of light emitted from the light emitting element for detection. A transparent substrate;
A plurality of transparent anode wiring and cathode wiring formed on the transparent substrate;
A plurality of light emitting elements that emit light by forward current;
A detection unit for detecting the luminance of the light emitting element or the voltage across the light emitting element ,
A first anode wiring and a second anode wiring branched from the anode wiring are formed on both sides of the common cathode wiring branched from the cathode wiring;
The plurality of light emitting elements include a first light emitting element group including a plurality of the light emitting elements that emit light by a forward current flowing in a direction from the first anode wiring to the common cathode wiring, and from the second anode wiring to the common cathode. A second light emitting element group composed of a plurality of the light emitting elements that emit light by a forward current flowing in the direction of the wiring ,
The switch electrically connects the anode wiring and the first anode wiring or the second anode wiring branched from the anode wiring according to the luminance or voltage detected by the detection unit. Lighting device. The lighting device according to any one of claims 1 to 5 ,
An illumination device comprising a front light disposed on a display surface of a liquid crystal panel. An electronic apparatus comprising the lighting device according to any one of claims 1 to 6 .

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