JP2011054511A - Lighting device, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device capable of extending a light-emitting period, and to provide an electronic device. <P>SOLUTION: The lighting device has at least a plurality of light-emitting elements 31 light-emitted by forward current, a DC power source 50, first and second wirings 51, 52 for supplying power from the DC power source 50 to the light-emitting element 31, and a switch 53 for switching polarity of the power supplied to the first and second wirings 51, 52. The plurality of light-emitting elements 31 includes first forward-connected light-emitting elements 31a connected so as to flow forward current when applying power from a positive electrode to the first wiring 51, and second reverse-connected light-emitting elements 31b connected so as to flow the forward current when applying the power from the positive electrode to the second wiring 52, and is connected between the first wiring 51 and the second wiring 52. <P>COPYRIGHT: (C)2011,JPO&INPIT

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.

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 it is configured to observe the display surface through the front light itself both when it is turned on and when it is turned 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 display. 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 forward current, a DC power supply, a first wiring that supplies power to the plurality of light emitting elements from the DC power supply, and a second wiring. At least a switch for switching the polarity of the power supplied to the first wiring and the second wiring, and the plurality of light emitting elements are configured to apply the positive power to the first wiring. A forward connection connected so that the forward current flows, and a reverse connection connected so that the forward current flows when the positive power is applied to the second wiring. The second wiring is connected between the first wiring and the second wiring.

  According to this configuration, since the light emitting element connected in the forward direction and the light emitting element connected in the reverse direction are connected between the first wiring and the second wiring, positive power is applied to the first wiring. Then, the light emitting elements connected in the forward direction emit light, and when the positive power is applied to the second wiring, the light emitting elements connected in the reverse direction emit light. Thus, by changing the polarity of the power supplied to the first wiring and the second wiring, it becomes possible to cause the light emitting elements to emit light alternately, and while one light emitting element emits light, the other light emitting element Does not emit light, the other light emitting element can be cooled. As a result, it is possible to suppress the deterioration due to the high temperature of the light emitting element and to extend the time during which the luminance is lowered (display quality is deteriorated) as compared with the case where one light emitting element emits light continuously. , Can improve the lifetime. Further, by continuously emitting light until the luminance of one light emitting element decreases to the lower limit threshold luminance, then switching to the other light emitting element to continuously emit light, only one light emitting element is continuously provided. Compared with the case of emitting light, the light emission time can be extended. As a result, the lifetime of the lighting device can be extended. In addition, when a failure occurs in one of the light-emitting elements, light can be emitted using the other light-emitting element.

  Application Example 2 In the illumination device according to the application example, the light emitting element is connected between the first wiring and the second wiring so that the forward connection and the reverse connection appear alternately. It is preferable that

  According to this configuration, one light emitting element (for example, a light emitting element connected in the forward direction) and the other light emitting element (for example, a light emitting element connected in the reverse direction) are alternately connected. It is possible to make the distance between one light emitting element adjacent to the element or the distance between the other light emitting element adjacent to the other light emitting element substantially uniform. Therefore, light emission by one light-emitting element or light emission by the other light-emitting element can be emitted in a balanced manner in the light-emitting region. Therefore, light can be emitted uniformly (with a good balance) from the entire lighting device.

  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, when the luminance is lowered to the lower limit threshold, the light emission by one light emitting element and the light emission by the other light emitting element are switched. Therefore, it is possible to maintain a higher luminance than the lower limit threshold.

  Application Example 4 In the illumination device according to the application example described above, it is preferable that the switch switches the polarity of the electric power according to the luminance or voltage detected by the detection unit.

  According to this configuration, the positive electrode power is applied to the first wiring or the second wiring according to the luminance or the 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. It is possible to emit light by switching to an element. 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 detection light emitting element.

  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 plurality of light emitting elements that emit light by forward current, an AC power supply, a first wiring that supplies power to the plurality of light emitting elements from the AC power supply, and a second wiring. A plurality of light emitting elements, wherein the plurality of light emitting elements are connected so that the forward current flows when the positive power is applied to the first wiring; and the second wiring And a reverse connection connected so that the forward current flows when the positive power is applied, and is connected between the first wiring and the second wiring. And

  According to this configuration, the light emitting element connected in the forward direction and the light emitting element connected in the reverse direction are connected between the first wiring and the second wiring, and further connected to the AC power supply. When the positive power is applied to the second wiring, the light emitting elements connected in the forward direction emit light, and when the positive power is applied to the second wiring, the light emitting elements connected in the reverse direction emit light. Thus, by changing the polarity of the power supplied to the first wiring and the second wiring, it becomes possible to cause the light emitting elements to emit light alternately, and while one light emitting element emits light, the other light emitting element Does not emit light, the other light emitting element can be cooled. As a result, it is possible to suppress the deterioration due to the high temperature of the light emitting element and to extend the time during which the luminance is lowered (display quality is deteriorated) as compared with the case where one light emitting element emits light continuously. , Can improve the lifetime. In addition, one light emitting element and the other light emitting element can alternately emit light without using a switch.

  Application Example 8 In the lighting device according to the application example, the light emitting element is connected between the first wiring and the second wiring so that the forward connection and the reverse connection appear alternately. It is preferable that

  According to this configuration, one light emitting element (for example, a light emitting element connected in the forward direction) and the other light emitting element (for example, a light emitting element connected in the reverse direction) are alternately connected. It is possible to make the distance between one light emitting element adjacent to the element or the distance between the other light emitting element adjacent to the other light emitting element substantially uniform. Therefore, light emission by one light-emitting element or light emission by the other light-emitting element can be emitted in a balanced manner in the light-emitting region. Therefore, light can be emitted uniformly (with a good balance) from the entire lighting device.

  Application Example 9 An illumination device according to this application example includes a transparent substrate, a plurality of transparent first wirings and second wirings formed on the transparent substrate, and a plurality of light emitting elements that emit light by forward current. And the plurality of light emitting elements are connected in a forward direction so that the forward current flows when a positive power is applied to the first wiring, and a positive polarity is connected to the second wiring. And a reverse connection that is connected such that the forward current flows when the power is applied, and is connected between the first wiring and the second wiring. The opening for emitting light is formed so as to overlap the first wiring or the second wiring.

  According to this configuration, since the light emitting element connected in the forward direction and the light emitting element connected in the reverse direction are connected between the first wiring and the second wiring, positive power is applied to the first wiring. For example, the light emitting elements connected in the forward direction emit light, and when the positive power is applied to the second wiring, the light emitting elements connected in the reverse direction emit light. Thus, by changing the polarity of the power supplied to the first wiring and the second wiring, it becomes possible to cause the light emitting elements to emit light alternately, and while one light emitting element emits light, the other light emitting element Does not emit light, the other light emitting element can be cooled. As a result, it is possible to suppress the deterioration due to the high temperature of the light emitting element and to extend the time during which the luminance is lowered (display quality is deteriorated) as compared with the case where one light emitting element emits light continuously. , Can improve the lifetime. Further, by continuously emitting light until the luminance of one light emitting element decreases to the lower limit threshold luminance, then switching to the other light emitting element to continuously emit light, only one light emitting element is continuously provided. Compared with the case of emitting light, the light emission time can be extended. As a result, the lifetime of the lighting device can be extended.

  Application Example 10 In the illumination device according to the application example described above, the illumination device described above is a front light disposed 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 11 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 of 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 equivalent circuit diagram which shows the state of the organic electroluminescent apparatus when an electric current is sent through the 1st wiring side. The equivalent circuit diagram which shows the state of the organic EL apparatus when an electric current is sent through the 2nd wiring side. 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. 8 is a schematic cross-sectional view taken along the line CC ′ of the organic EL device shown in FIG. FIG. 8 is a schematic cross-sectional view taken along the line DD ′ of the organic EL device shown in FIG. 7. 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. The wave form diagram which shows the waveform of the voltage applied to an organic electroluminescent apparatus. 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.

  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. The front light has a small light emitting area so as not to affect the display. 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. FIG. 4 is an equivalent circuit diagram showing a state of the organic EL device when a current is passed through the first wiring side. FIG. 5 is an equivalent circuit diagram showing a state of the organic EL device when a current is supplied to the second wiring side. Hereinafter, the configuration and operation of the organic EL device will be described with reference to FIGS.

  As shown in FIG. 3, the organic EL device 12 uses a DC power source 50 that supplies DC power as a power source. In addition, the organic EL device 12 includes a first wiring 51 connected to one of the DC power supplies 50 and a second wiring 52 connected to the other of the DC power supplies 50. The first wiring 51 and the second wiring 52 are branched in a comb-like shape and are arranged alternately. A plurality of light emitting elements 31 that emit light by forward current are provided between the first wiring 51 and the second wiring 52 that are alternately arranged. In other words, the plurality of light emitting elements 31 are connected in parallel.

  The plurality of light emitting elements 31 connected in parallel have the anode 35 (anode) connected to the first wiring 51, the cathode 37 (cathode) connected to the second wiring 52, and between the anode 35 and the cathode 37. It has the 1st light emitting element 31a in which the light emission functional layer 36 was provided. Further, the light emitting element 31 has the cathode 37 (cathode) side connected to the first wiring 51, the anode 35 (anode) side connected to the second wiring 52, and the light emitting functional layer 36 is provided between the anode 35 and the cathode 37. The second light emitting element 31b is provided. The light emitting element 31 can be regarded as a diode equivalently.

  The first light emitting elements 31a and the second light emitting elements 31b are alternately connected in parallel. The adjacent first light emitting element 31a and second light emitting element 31b constitute one pixel.

  In addition, the organic EL device 12 includes a switch 53 (54, 55) that switches a direction in which a current flows (a polarity of electric power). The switch 53 includes a first switch 54 and a second switch 55. The first switch 54 includes a first anode terminal 54 a electrically connected to the positive electrode side of the DC power supply 50 and a first cathode terminal 54 b electrically connected to the negative electrode side of the DC power supply 50. ing. The second switch 55 is provided with a second anode terminal 55a electrically connected to the positive electrode side of the DC power supply 50 and a second cathode terminal 55b electrically connected to the negative electrode side of the DC power supply 50. ing.

  Next, referring to FIG. 4, the operation of the organic EL device 12 in which the first wiring 51 is electrically connected to the first anode terminal 54a and the second wiring 52 is electrically connected to the second cathode terminal 55b. Will be described. First, when the DC power supply 50 is turned on, power (positive power) is supplied from the DC power supply 50 to the first wiring 51, and a current flows to the first wiring 51 side. The first light emitting element 31a in which the first wiring 51 and the anode 35 are electrically connected (forward-connected) in the light emitting element 31 emits light. The first light emitting element 31 a emits light with a luminance corresponding to the amount of current flowing through the light emitting functional layer 36. In this case, the second light emitting element 31b does not emit light because it is connected in the reverse direction.

  On the other hand, referring to FIG. 5, the operation of the organic EL device 12 in which the first wiring 51 is electrically connected to the first cathode terminal 54b and the second wiring 52 is electrically connected to the second anode terminal 55a. explain. First, when the DC power supply 50 is turned on, power (positive power) is supplied from the DC power supply 50 to the second wiring 52, and a current flows to the second wiring 52 side. Then, the second light emitting element 31b in which the second wiring 52 and the anode 35 are electrically connected (reversely connected) in the light emitting element 31 emits light. The second light emitting element 31 b emits light with a luminance corresponding to the amount of current flowing through the light emitting functional layer 36. In this case, the first light emitting element 31a does not emit light because it is connected in the forward direction.

  In this way, by changing the connection state of the first switch 54 and the second switch 55 and changing the direction of current flow, either the first light emitting element 31a or the second light emitting element 31b constituting one pixel emits light. Can be made.

  FIG. 6 is a schematic plan view showing the structure of the organic EL device. FIG. 7 is a schematic enlarged view showing the portion B of the organic EL device shown in FIG. 6 in an enlarged manner. FIG. 8 is a schematic cross-sectional view taken along the line CC ′ of the organic EL device shown in FIG. FIG. 9 is a schematic cross-sectional view taken along the line DD ′ of the organic EL device shown in FIG. 8 and 9, 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. 6, the organic EL device 12 includes a light emitting region 56 in which the light emitting elements 31 are regularly arranged with a predetermined interval, and a peripheral region 57 that is a region around the light emitting region 56. Yes.

  The light emitting region 56 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 56, strip-shaped first wirings 51 and strip-shaped second wirings 52 are arranged alternately and substantially in parallel. Both the first wiring 51 and the second wiring 52 are formed of ITO, which is a transparent conductive material, and do not affect the visibility of images formed on the liquid crystal panel 11.

  As shown in FIGS. 7 to 9, the light emitting element 31 overlaps the first light emitting element 31 a in which the light emitting functional layer 36 is formed in a region overlapping the first wiring 51 in plan view, and the second wiring 52 in plan view. And a second light emitting element 31b having a light emitting functional layer 36 formed in the region.

  The light emitting element 31 includes a first direction in which the first light emitting element 31a and the second light emitting element 31b are paired, the first wiring 51 and the second wiring 52 extend, and a second direction orthogonal to the first direction. A plurality are provided in the direction (see FIG. 6). 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 56.

  More specifically, in the first light emitting element 31a, an island-shaped (pad-shaped) light emitting functional layer 36 is provided on a part of the first wiring 51 on the transparent substrate 32 in a plan view. An insulating film 58 is provided around the light emitting functional layer 36. As shown in FIG. 8, a cathode 37 made of aluminum (Al) or the like having one end electrically connected to the second wiring 52 is provided on the light emitting functional layer 36. The first wiring 51 and the second wiring 52 are electrically insulated by the insulating film 58.

  In the second light emitting element 31b, an island-shaped (pad-shaped) light emitting functional layer 36 is provided on a part of the second wiring 52 on the transparent substrate 32 in plan view. An insulating film 58 is provided around the light emitting functional layer 36. As shown in FIG. 9, a cathode 37 made of aluminum (Al) or the like having one end electrically connected to the first wiring 51 is provided on the light emitting functional layer 36. The first wiring 51 and the second wiring 52 are electrically insulated by the insulating film 58. In addition, as shown in FIG. 7, the cathode 37 constituting the first light emitting element 31a and the cathode 37 constituting the second light emitting element 31b are separated via an insulating film 58.

  In such a configuration, when the first wiring 51 is connected to the positive pole of the DC power supply 50 and the second wiring 52 is connected to the negative pole of the DC power supply 50, the first light emitting element 31a emits light. In addition, when the second wiring 52 is connected to the positive pole of the DC power supply 50 and the first wiring 51 is connected to the negative pole of the DC power supply 50, the second light emitting element 31b emits light.

  As described above, by switching the polarities of the first wiring 51 and the second wiring 52 using the switch 53, the first light emitting element 31a and the second light emitting element 31b emit light alternately. If used in this way, the lifetime of the organic EL device 12 (front light) can be extended.

  In the organic EL device 12 as shown in FIG. 6, the light emitting region 56 is rectangular and the light emitting elements 31 are regularly arranged in the light emitting region 56. However, the present invention is not limited to this mode. The light emitting region 56 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.

  10 to 13 are schematic cross-sectional views illustrating the method of manufacturing the organic EL device in the order of steps. More specifically, FIG. 10A to FIG. 13A are schematic cross-sectional views showing a manufacturing method centering on a first light emitting element constituting an organic EL device in order of steps. Each figure (b) is a schematic sectional view showing a manufacturing method centering on the second light emitting element in the order of steps. Hereinafter, a method for manufacturing the organic EL device (first light emitting element, second light emitting element) will be described with reference to FIGS.

  First, as shown in FIG. 10, the first wiring 51 and the second wiring 52 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 wiring 51 is used as the anode 35. On the other hand, in the second light emitting element 31b, the second wiring 52 is used as the anode 35.

  The second wiring 52 of the first light emitting element 31 a and the first wiring 51 of the second light emitting element 31 b are used for connection to the cathode 37. The first wiring 51 and the second wiring 52 are made of a metal oxide conductive film having optical transparency such as ITO. In addition, the first wiring 51 and the second wiring 52 and each layer described below can be sequentially formed using, for example, a known vacuum deposition method.

  Next, as shown in FIG. 11, an insulating film 58 is formed on the transparent substrate 32 and the wiring (the first wiring 51 and the second wiring 52) so that the regions of the light emitting section 61 and the contact section 62 are opened. . The insulating film 58 is made of, for example, an acrylic resin or a polyimide resin.

  Next, as shown in FIG. 12, the light emitting functional layer 36 is formed. Specifically, the light emitting functional layer 36 is formed on a part of the first light emitting element 31a on the first wiring 51 and the insulating film 58 and on a part of the second light emitting element 31b on the second wiring 52 and the insulating film 58. Form. As described above, in the light emitting functional layer 36, 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 are sequentially laminated (in FIG. 12, one layer is illustrated). ).

  Next, as shown in FIG. 13, a cathode 37 is formed. Specifically, the cathode 37 is formed on the light emitting functional layer 36, the second wiring 52, and the insulating film 58 in the first light emitting element 31 a. In the second light emitting element 31b, the cathode 37 is formed on the first wiring 51, the light emitting functional layer 36, and the insulating film 58. As described above, the cathode 37 on the first light emitting element 31a and the cathode 37 on the second light emitting element 31b are formed separately so as not to be electrically connected (see FIG. 7).

  By forming in this way, as described above, when a current flows to the first wiring 51 side, a current flows from the first wiring 51 to the second wiring 52, and the first light emitting element 31a emits light. Further, when a current is supplied to the second wiring 52 side, a current flows from the second wiring 52 to the first wiring 51, and the second light emitting element 31b emits light.

  In addition, since the first wiring 51 and the second wiring 52 and other layers can be formed in the same process, the number of processes can be reduced and the first light-emitting element 31a and the second light-emitting element 31a and the second having no difference in polarity can be obtained. The 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 in parallel, and if a current is passed through the first wiring 51 side, the first light emitting element 31a emits light, If a current is supplied to the second wiring 52 side, the second light emitting element 31b emits light. Then, by switching the direction of the flowing current using the switch 53 (54, 55), the first light emitting element 31a and the second light emitting element 31b can be made to emit light alternately, and one of the light emitting elements emits light. During this time, the other light emitting element does not emit light, so that the other light emitting element 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. In addition, 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 switched to the other light emitting element (for example, the second light emitting element 31b). By 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 can be extended.

  (2) According to the first embodiment, since the first light emitting elements 31a and the second light emitting elements 31b are alternately connected, the distance between the first light emitting element 31a and the adjacent first light emitting element 31a, or The distance between the second light emitting element 31b and the adjacent second light emitting element 31b can be made substantially uniform. Therefore, the light emission by the first light emitting element 31 a or the light emission by the second light emitting element 31 b can be emitted in a balanced manner in the light emitting region 56. Therefore, light can be emitted uniformly from the entire organic EL device 12 (illumination device).

  (3) According to the first embodiment, since the plurality of first light emitting elements 31a and the second light emitting elements 31b are connected in parallel, even if one of the light emitting elements is defective, the switch 53 is used. By reversing the direction of the flowing current, the other light emitting element can emit light.

  (4) 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 the vapor deposition method. Can be manufactured relatively easily.

(Second Embodiment)
<Configuration of lighting device>
FIG. 14 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.

  The organic EL device 112 according to the second embodiment includes a detection light emitting element 131 and a detection unit (light sensor 111) 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. 14, the organic EL device 112 according to the second embodiment is connected to the first wiring 51 connected to one of the DC power supplies 50 and the other of the DC power supplies 50 as in the first embodiment. The first wiring 51 having the second wiring 52 and the second wiring 52 branched into a plurality are alternately arranged, and the first light emitting element 31a and the second light emitting element 31b are connected in parallel to these. Has been. Further, similarly to the first embodiment, the first switch 54 and the second switch 55 are provided, and the direction of the flowing current can be switched.

  In such an organic EL device 112, as a characteristic part of the second embodiment, a detection light emitting element 131 used for detecting luminance is provided between the first wiring 51 and the second wiring 52. . The detection light emitting element 131 includes a first detection light emitting element 131a that emits light when a current flows to the first wiring 51 side, and a second detection light emitting element that emits light when a current flows to the second wiring 52 side. 131b. That is, when the first light emitting element 31a provided in the light emitting region 56 is caused to emit light, the first 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 56 is caused to emit light, the second detection light emitting element 131b also emits light simultaneously.

  An optical sensor 111 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 111, for example, a photodiode, a phototransistor, CSD, or the like can be used. Thus, by detecting the luminance via the detection light emitting element 131, the luminance of the first light emitting element 31a and the second light emitting element 31b can be detected. The connection state of the first switch 54 and the second switch 55 is switched according to the detection result of the luminance by the optical sensor 111 (for example, when the luminance decreases and reaches the lower limit threshold value).

  Specifically, first, an operation when the first wiring 51 is electrically connected to the first anode terminal 54a and the second wiring 52 is electrically connected to the second cathode terminal 55b will be described. When the DC power supply 50 is turned on, a current flows to the first wiring 51 side, the first light emitting element 31a emits light and the first detecting light emitting element 131a emits light. At this time, the luminance of the first detection light emitting element 131a is detected by the optical sensor 111. Then, when the luminance reaches the lower limit threshold (when the luminance decreases to a predetermined luminance), for example, the light emission of the first light emitting element 31a is switched to the light emission of the second light emitting element 31b.

  Next, an operation when the first wiring 51 is electrically connected to the first cathode terminal 54b and the second wiring 52 is electrically connected to the second anode terminal 55a will be described. When the DC power supply 50 is turned on, a current flows to the second wiring 52 side, the second light emitting element 31b emits light, and the second detection light emitting element 131b emits light. At this time, the luminance of the second light emitting element for detection 131b is detected by the optical sensor 111. When the luminance reaches the lower limit threshold value, for example, the new organic EL device 112 is replaced.

  Note that a switching mechanism 113 that switches the connection state of the first switch 54 and the second switch 55 according to the detection value of the optical sensor 111 is preferably provided. Specifically, the optical sensor 111, the first switch 54, and the second switch 55 are provided so as to interlock with each other via the switching mechanism 113.

  Specifically, first, the first light emitting element 31a is caused to emit light. When it is determined by the optical sensor 111 that the luminance of the first detection light emitting element 131a has decreased to the luminance that is the lower limit threshold, a signal is sent to the switching mechanism 113, so that the first switch 54 and the second switch 55 The connection state changes, and the light emission of the first light emitting element 31a is switched to the light emission of the second light emitting element 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 57 outside the light emitting region 56 of the organic EL device 112. Since the optical sensor 111 is not disposed in the light emitting region 56, the luminance can be detected without reducing the luminance necessary for the light emitting region 56. 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, 31b) are provided in the peripheral region 57, it is necessary to check the two light-emitting states. Thus, it can be determined which light emitting element 31 (31a, 31b) is emitting light.

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

  (5) According to the second embodiment, since the optical sensor 111 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 brightness is detected by the optical sensor 111, it is possible to always emit light with a brightness higher than the lower limit threshold of brightness.

  (6) According to the second embodiment, since the luminance is detected using the detection light emitting elements 131 a and 131 b, for example, the detection light emitting elements 131 a and 131 b are provided in the peripheral region 57 outside the light emitting region 56. The luminance of the light emitting elements 31a and 31b can be detected without reducing the luminance necessary for the light emitting region 56.

(Third embodiment)
<Configuration of lighting device>
FIG. 15 is an equivalent circuit diagram showing an electrical configuration of the organic EL device as the illumination device of the third embodiment. FIG. 16 is a waveform diagram showing a waveform of a voltage applied to the organic EL device. Hereinafter, the configuration of the organic EL device will be described with reference to FIGS. 15 and 16.

  The organic EL device 212 according to the third embodiment is different from the first embodiment in that an AC power supply 250 that supplies AC power is used as a power source. 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. 15, the organic EL device 212 of the third embodiment has a first wiring 51 connected to one of the AC power supplies 250 and a second wiring 52 connected to the other of the AC power supplies 250. The first wirings 51 and the second wirings 52 branched into a plurality are alternately arranged, and the first light emitting element 31a and the second light emitting element 31b are connected in parallel to these.

  Further, as shown in FIG. 16, the relationship between the voltage and the time when the AC power source 250 is used is alternately switched between a positive voltage and a negative voltage as time passes. For example, when the voltage is positive, current flows through the first wiring 51 and the first light emitting element 31a emits light. On the other hand, when the voltage is negative, current flows to the second wiring 52 side, and the second light emitting element 31b emits light.

  Thus, by alternately emitting (driving) the first light emitting element 31a and the second light emitting element 31b, while one of the light emitting elements (for example, the first light emitting element 31a) emits light and generates heat, The other light emitting element (for example, the second light emitting element 31b) is cooled.

  Thereby, it becomes possible to suppress the temperature rise of the 1st light emitting element 31a and the 2nd light emitting element 31b, and it can suppress that the light emitting element 31 deteriorates. As a result, it is possible to extend the time for light emission with a brightness brighter than the lower threshold. The timing for switching between the first light emitting element 31a and the second light emitting element 31b is preferably set to an optimal balance by adjusting the frequency of the AC power supply 250 while confirming the temperature rise of the light emitting element 31, for example. .

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

  (7) According to the third embodiment, since the first light emitting element 31a and the second light emitting element 31b are connected in parallel and further connected to the AC power supply 250, a current flows to the first wiring 51 side. Then, the first light emitting element 31a emits light, and if a current flows to the second wiring 52 side, the second light emitting element 31b emits light. In this way, by alternately changing the direction of the current supplied by the AC power supply 250, the first light emitting element 31a and the second light emitting element 31b can be made to emit light alternately, and one light emitting element emits light continuously. Compared with the case where it was made, the time when a brightness | luminance falls (display quality deteriorates) can be extended. As a result, the lifetime of the organic EL device 212 (illumination device) can be extended. In addition, the first light emitting element 31a and the second light emitting element 31b can alternately emit light without using the switch 53.

(Fourth embodiment)
<Configuration of electronic equipment>
FIG. 17 is a schematic diagram illustrating a mobile phone as an example of an electronic apparatus including the organic EL device described above. Hereinafter, a configuration of a mobile phone including the organic EL device will be described with reference to FIG.

  As shown in FIG. 17, the mobile phone 71 has a display unit 72 and operation buttons 73. The display unit 72 can perform high-quality display such that the light emission time can be improved by the organic EL device 12 incorporated therein. The organic EL device 12 described above can be used for various electronic devices such as a mobile computer, a digital camera, a digital video camera, an in-vehicle device, an audio device, an exposure device, and an illumination device in addition to the mobile phone 71 described above.

  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 second 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 111. For example, as shown in FIG. The luminance may be obtained. FIG. 18 is an equivalent circuit diagram electrically showing the configuration of the organic EL device 312 of the first modification. FIG. 19A is a graph showing the relationship between time and luminance. FIG. 19B is a graph showing the relationship between time and voltage.

  First, as shown in FIG. 19A, 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. 19B, as the luminance decreases, the voltage increases with time.

  Utilizing such characteristics, as shown in FIG. 18, a voltage value at which a voltmeter 311 as a detection unit disposed between the first wiring 51 and the second wiring 52 serves as a lower threshold of luminance is used. Is detected (when the brightness is lowered to a threshold value), the switches 54 and 55 are switched to change the light emission of the first light emitting element 31a to the light emission of the second light emitting element 31b, for example. The switches 54 and 55 may be switched manually, or may be switched automatically using the switching mechanism 113 (see FIG. 14). 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 period of time than in the case where light is emitted from only one light emitting element. Further, the luminance can be determined by the driving voltage without directly detecting light.

(Modification 2)
As described in the second embodiment and the first modification described above, the first light emitting element 31a continuously emits light until the luminance falls to a certain lower threshold, and then the second light emitting element 31b is switched to continue. Instead of emitting light, the following may be used. 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 111 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 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 produced by changing the direction of the flowing current. 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 device 12 is 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 ... 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 ... counter 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 ... light emitting functional layer, 37 ... cathode, 41 ... positive Hole injection layer, 42 ... hole transport layer, 43 ... light emitting layer, 44 ... electron transport layer, 45 ... electron injection layer, 46 ... transparent layer, 47 ... transflective layer, 48 ... light interference layer, 50 ... DC power supply 51 ... 1st wiring, 52 ... 2nd wiring, 53 54, first switch, 54a, first anode terminal, 54b, first cathode terminal, 55, second switch, 55a, second anode terminal, 55b, second cathode terminal, 56, light emitting region, 57, peripheral 58, insulating film, 61 ... light emitting part (opening), 62 ... contact part, 71 ... mobile phone, 72 ... display part, 73 ... operation button, 111 ... optical sensor as detection part, 113 ... switching mechanism, 131... Light emitting element for detection, 131 a... Light emitting element for first detection, 131 b... Light emitting element for second detection, 311.

Claims (11)

A plurality of light emitting elements that emit light by forward current;
DC power supply,
A first wiring and a second wiring for supplying power from the DC power source to the plurality of light emitting elements;
A switch for switching the polarity of the power supplied to the first wiring and the second wiring,
When the positive power is applied to the first wiring, the plurality of light emitting elements are connected so that the forward current flows, and the positive power is applied to the second wiring. And a reverse connection connected such that the forward current flows when connected, the illumination device being connected between the first wiring and the second wiring. The lighting device according to claim 1,
The lighting device is characterized in that the light emitting element is connected between the first wiring and the second wiring so that the forward connection and the reverse connection appear alternately. The lighting device according to claim 1 or 2,
An illumination device comprising: a detection unit configured to detect a luminance of the light emitting element or a voltage across the light emitting element. The lighting device according to claim 3,
The switch is configured to switch the polarity of the power according to the luminance or voltage detected by the detection unit. The lighting device according to claim 3 or 4,
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 3 thru | or 5, 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 plurality of light emitting elements that emit light by forward current;
AC power supply,
A first wiring and a second wiring for supplying power from the AC power source to the plurality of light emitting elements;
Comprising at least
When the positive power is applied to the first wiring, the plurality of light emitting elements are connected so that the forward current flows, and the positive power is applied to the second wiring. And a reverse connection connected such that the forward current flows when connected, the illumination device being connected between the first wiring and the second wiring. The lighting device according to claim 7,
The lighting device is characterized in that the light emitting element is connected between the first wiring and the second wiring so that the forward connection and the reverse connection appear alternately. A transparent substrate;
A plurality of transparent first wiring and second wiring formed on the transparent substrate;
A plurality of light emitting elements that emit light by forward current,
When the positive power is applied to the first wiring, the plurality of light emitting elements are connected so that the forward current flows, and the positive power is applied to the second wiring. And a reverse connection connected so that the forward current flows, and is connected between the first wiring and the second wiring,
An opening for emitting light from the light emitting element is formed so as to overlap the first wiring or the second wiring. The lighting device according to any one of claims 1 to 9,
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 claim 1.

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