JP2008177092A - Light-emitting device, and printing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device in which heat formed in the organic EL element accompanying the light emission of the organic EL element can be removed efficiently. <P>SOLUTION: The light-emitting element substrate 21 in which a plurality of organic EL elements 20 is formed in an array state at a prescribed spacing, the opposing substrate 28 which is installed opposed to the light-emitting element substrate 21 and in which a liquid storage space 48A for storing a liquid medium 10 is formed are made to be equipped, while the light-emitting element substrate 21 and the opposing substrate 28 are adhered with a sealing member 41 so that a light projecting region in the organic EL element 20 and the liquid storage space 48A are arranged to be neighbored. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device and a printing device that use a light emitting element as a light source.

  Conventionally, a light emitting device using an organic EL element as a light source is known, and is used for an exposure device in a printing apparatus, for example. As a technique related to such a light emitting device, for example, Patent Document 1 discloses an image forming apparatus using an organic EL element.

  In the technique disclosed in Patent Document 1, an organic layer including a light emitting layer made of an organic material is sandwiched between a first electrode (transparent anode) and a second electrode (reflection cathode), and the first electrode and the Driving is performed by applying a voltage between the second electrode and the electrode by a power supply means.

Here, in the image forming apparatus disclosed in Patent Document 1, the substrate (sealing substrate) provided on the surface opposite to the light emission surface of the light generated in the light emitting layer is included in the substrate. A heat radiating means for radiating heat to the outside is formed.
JP 2005-149853 A

  By the way, in a printing apparatus using an exposure device that uses an organic EL element as a light source, in order to obtain a light amount necessary for a photoconductor in the printing apparatus or the like, exposure is performed while suppressing the light emission intensity per unit time by the organic EL element. It is necessary to lengthen the exposure time or shorten the exposure time by increasing the emission intensity per unit time. In the former, the printing time is delayed, and in the latter, the printing time is shortened. However, the organic EL element is promoted to be deteriorated due to heat generated by overcurrent control. Further, there is a problem that the decrease in luminance and the generation of heat over time lead to a decrease in exposure amount and image quality deteriorates.

  In the technique disclosed in Patent Document 1, the heat radiation means is formed on the sealing substrate for sealing the light emitting layer, the first electrode, and the second electrode. Therefore, since the heat generated in the light emitting layer is radiated through the sealing substrate, the cooling efficiency of the light emitting layer is poor.

  The present invention has been made in view of the above circumstances, and provides a light emitting device and a printing device that can efficiently remove heat generated in an organic EL element due to light emission of the organic EL element in a short time. For the purpose.

In order to achieve the above object, a light emitting device according to the first aspect of the present invention comprises:
A light emitting element substrate in which a plurality of light emitting elements are arranged at predetermined intervals;
A counter substrate provided facing the substrate;
A medium storage space interposed between the light emitting element and a light emitting region from which light of the light emitting element is emitted;
It is characterized by comprising.

  It is preferable that the heat capacity of the medium filling the medium storage space is at least larger than the heat capacity of the counter substrate.

  It is preferable that the medium storage space is formed in a lens shape that collects light emitted from a light emitting region in the light emitting element.

A light-emitting device according to the second aspect of the present invention includes:
A substrate on which a plurality of light emitting elements are arranged at a predetermined interval;
A counter substrate provided facing the substrate;
A medium storage space interposed between the light emitting element and a light emitting region from which light of the light emitting element is emitted;
A lens structure that collects light from the light emitting element;
It is characterized by comprising.

  In the light emitting device according to the first and second aspects of the present invention, a heat radiating film is formed in a portion where the medium storage space is formed in a portion that does not block the light emitted from the light emitting surface of the light emitting element. It is preferable.

  The medium may be a liquid medium or a gas medium.

  It is preferable that the heat dissipation film is continuously formed up to a place where the counter substrate is adjacent to the outside of the light emitting device.

  The medium storage space may be formed in a lens shape that collects light of the light emitting element.

The light emitting device according to the third aspect of the present invention is
A light-emitting element substrate in which a plurality of light-emitting elements are constructed in an array at predetermined intervals;
A counter substrate including a lens structure portion formed in a lens shape to collect light emitted from a light emitting region in the light emitting element;
A seal member that bonds the light emitting element substrate and the counter substrate so that the light emitting region of the light emitting element and the lens structure portion are adjacent to each other;
Comprising
The boundary region between the substrate and the counter substrate bonded by the sealing member and the lens structure portion are filled with a liquid medium for storing a medium having a larger heat capacity than any member in contact with the light emitting element. It is characterized by being.

  Further, the printing apparatus includes the light emitting device according to any one of the aspects of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the light-emitting device and printing apparatus which can remove efficiently the heat which generate | occur | produced in the light emitting element with light emission of a light emitting element can be provided.

[First Embodiment]
Hereinafter, a light emitting device and a printing apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an example of a configuration of a printing apparatus using the light emitting device according to the first embodiment. First, as shown in FIG. 1, a printing apparatus using the light emitting device according to the first embodiment is an exposure comprising a photosensitive drum 1, a light emitting device 2A according to the first embodiment, and a rod lens array 2B. The image forming apparatus includes a unit 2, a charging roller 3, an eraser light source photoconductor 4, a cleaning member 5, a developing device 6 including a developing roller 6 a, a transfer roller 8, a fixing roller 9, and a conveyance belt 11. . Note that reference numeral 7 denotes printing paper.

  The photoreceptor drum 1 is a negatively charged OPC (Organic Photo Conductor) photoreceptor (organic photoreceptor). In view of this, the charging roller 3 is a negative charger. The developing device 6 is a developing device for developing with negatively charged toner. The light emitting device 2A is configured by arranging a plurality of organic EL elements (light emitting elements) in an array, which will be described in detail later.

  By the way, in the printing apparatus shown in FIG. 1, printing is roughly performed by the following processes. First, when the charging roller 3 comes into contact with the surface of the rotating photosensitive drum 1, the contacted surface of the photosensitive drum 1 is uniformly charged with a negative potential. Subsequently, the light emitting device 2A irradiates the photosensitive drum 1 with light through the rod lens array 2B, and an electrostatic latent image is formed on the photosensitive drum 1. Thereafter, the developer 6 attaches toner to the electrostatic latent image. Then, the toner attached to the electrostatic latent image is transferred to the printing paper 7 by the transfer roller 8. Hereinafter, such a printing process will be described in detail.

  First, the photosensitive drum 1 is initialized to a negative potential supplied from a charging power source (not shown) and relatively close to or equal to a developing voltage output from a developing device 6 described later. A charging voltage is applied by the charging roller 3. As a result, the peripheral surface of the photosensitive drum 1 is uniformly negatively charged and is initialized in terms of potential (becomes an initialized charging state).

  Then, optical writing (exposure) according to the printing information is performed on the photosensitive drum 1 whose peripheral surface has been initialized and charged by the light emitting device 2A. As a result, the initialization charging portion that remains in the initialization charged state because no exposure is performed, and the exposure charging voltage of about −50 (V) that is a negative potential relatively higher than the initialization charging portion by the exposure. Is formed on the peripheral surface of the photosensitive drum 1.

  Here, the toner charged in the developing unit 6 and charged to a weak negative potential is rotated and conveyed by the developing roller 6a to the opposing portion between the developing roller 6a and the photosensitive drum 1. At this time, the developing roller 6a is applied with a developing voltage of about −250 (V), which is lower than the exposure charging unit, from a power source (not shown). Therefore, the exposure charging portion of about −50 (V) of the electrostatic latent image on the photosensitive drum 1 is about 200 (V) higher than the development voltage, and the initialization charging portion is different from the development voltage. Is a voltage whose absolute value is sufficiently smaller than 200 (V).

  Due to the difference in potential difference from the development voltage in these electrostatic latent images, the exposure charging portion in the electrostatic latent image having a positive polarity relative to the developing roller 6a is charged to a negative polarity. On the other hand, the toner image does not adhere to the initialization charging portion because an electric field that attracts the toner electrostatically does not occur in the initialization charging portion. The toner image is conveyed to a transfer portion where the photosensitive drum 1 and the transfer roller 8 face each other by the rotation of the photosensitive drum 1.

  The toner adhesion amount (developed image density) in the toner image formed as described above is generated according to the exposure amount of the photosensitive drum 1 by the light emitting device 2A. It is determined by the potential on the peripheral surface, that is, the potential difference from the development voltage.

  By the way, as described above, when the toner image is transported to the transfer unit, the printing paper 7 is transported to the transfer unit by the transport belt 11. In the transfer unit, the toner image is transferred onto the printing paper 7 by the transfer roller 8. The printing paper 7 to which the toner image is transferred in this way is further conveyed downstream, and after the toner image is thermally fixed by the fixing roller 9, the printing paper 7 is discharged to the outside of the printing apparatus. The

  Hereinafter, the basic structure of the light emitting device 2A will be described with reference to FIGS.

  As shown in FIG. 2, the organic EL element 20 is formed on a light emitting element substrate 21 such as glass, and the upper surface is sealed by a counter substrate 28 such as glass. Here, the organic EL element 20 has either a top emission structure that emits the light 51 of the light emitting layer 25 from the counter substrate 28 side or a top emission structure that emits the light 51 of the light emitting layer 25 from the EL substrate 21 side. You can choose. In the case of the top emission structure, specifically, as the organic EL element 20, a light-reflective pixel electrode 23, a hole transport layer (HTL) 24, a light-emitting layer 25, and an electron transport layer (ETL) are formed on the light-emitting element substrate 21. 26 and a light transmissive counter electrode 27 are formed in this order. Here, the hole transport layer 24, the light emitting layer 25, and the electron transport layer (ETL) 26 are organic EL layers containing an organic compound. The organic EL layer is not limited to the above, and may be, for example, a hole transport layer and an electron transport light emitting layer, or only a hole transport / electron transport light emitting layer, or a hole transport light emitting layer and an electron transport layer. In addition, a carrier transport layer may be appropriately interposed therebetween, or a combination of other carrier transport layers may be used.

  The pixel electrode 23 functions as an anode, and is a transparent metal layer such as an aluminum alloy located on the lower layer side, and a transparent material such as tin-doped indium oxide (ITO) or zinc-doped indium oxide located on the upper layer side. A laminated structure with a transparent conductive metal oxide layer having an electrode material may be used, or a single layer of a reflective metal layer such as an aluminum alloy may be used.

  The counter electrode 27 functions as a transparent cathode, and has an electron injection layer having a low work function such as barium, magnesium, lithium, etc. located on the lower layer side, and a transparent conductive metal oxide layer similar to the above located on the upper layer side. Or a laminated structure. The counter electrode 27 may be a single electrode common to the plurality of organic EL elements 20A.

  When the pixel electrode 23 is a cathode and the counter electrode 27 is an anode, the carrier transport layer in contact with the pixel electrode 23 is an electron transport layer, and the carrier transport layer in contact with the counter electrode 27 is a hole transport layer. Become a layer.

  Further, in the case of the bottom emission structure, the pixel electrode 23 is a transparent conductive layer having a transparent electrode material such as ITO or zinc-doped indium oxide, and the counter electrode 27 has a work function such as barium, magnesium, or lithium positioned on the lower layer side. A stacked structure of a low electron injection layer and a light reflective metal layer such as aluminum positioned on the upper layer side may be employed.

  Then, by applying a predetermined voltage between the pixel electrode 23 and the counter electrode 27, holes or electrons from the pixel electrode 23, electrons or holes from the counter electrode 27, and the light emitting layer. The light emitting layer 25 recombines holes and electrons to emit light. The light 51 generated by this light emission is diffusely radiated.

  By the way, since the light emitted from the light emitting layer 25 of the organic EL element 20 is radiated in a radial manner, the light is emitted through the counter substrate 28 or the light emitting element substrate 21 in the case of the top emission structure or the bottom emission structure. . In addition to the rod lens array 2B, the following measures may be taken in order to increase the light extraction efficiency.

  For example, each of the plurality of organic EL elements 20 formed on the light emitting element substrate 21 has a fiber function, thereby forming a pseudo light emitter on the surface of the light emitting element substrate 21. Thus, in order to give the light emitting element substrate 21 a fiber function, for example, a known technique called a photonic crystal fiber is used. Specifically, a photonic crystal fiber in which an air hole corresponding to a clad extends in the thickness direction of the light emitting element substrate 21 is provided in the light emitting element substrate 21 or formed integrally with the light emitting element substrate 21. Has been. Since such a fiber for controlling the directivity of light is provided, the light of the organic EL element 20 can be efficiently emitted from the light emitting element substrate 21.

  By the way, in the first embodiment, a small-diameter spot is formed on the photosensitive drum 1 at a predetermined distance from the exposure unit 2 by the exposure unit 2 including the light emitting device 2A and the rod lens array 2B. The light 51 of the organic EL element 20 is collected. Hereinafter, a detailed configuration of the exposure unit 2 when the organic EL element 20 has a top emission structure will be described with reference to FIGS.

  In the light emitting device 2 </ b> A, a plurality of organic EL elements 20 are arranged side by side in the longitudinal direction of the EL substrate 21 and the counter substrate 28. Here, the plurality of organic EL elements 20 are sandwiched between the light emitting element substrate 21 and the counter substrate 28. Therefore, although the organic EL element 20 is not shown in FIG. 3, since the organic EL element 20 and the light emitting region 33 have a one-to-one correspondence, the arrangement of the organic EL elements 20 is easy from FIG. Can be guessed. Here, the light emitting region 33 is a region provided on the counter substrate 28 in order to emit the light 51 emitted from the organic EL element 20 from the light emitting device 2A. In the bottom emission structure as well, a plurality of light emitting regions 33 are similarly arranged on the outer surface of the light emitting element substrate 21 along the longitudinal direction of the EL substrate 21 and the counter substrate 28.

  That is, the light emitting device 2A emits a plurality of light beams in the main scanning direction of the exposure scanning to the photosensitive drum 1 shown in FIG. 1 (the width direction of the photosensitive drum 1, that is, the width direction of the printing paper 7). The region 33, that is, the plurality of organic EL elements 20 are arranged in a line to form an organic EL array. If the printing apparatus is a printing apparatus capable of printing at a printing density of 1200 dpi (dots / inch) to the full width using, for example, A4 size printing paper in the vertical direction, this organic EL array is approximately 14,000 pieces. The organic EL element 20 is provided. A pulse voltage in accordance with print information output from a host device (not shown) is applied to each of the organic EL elements 20. That is, the light emission of each organic EL element 20 is selectively controlled.

  The organic EL element is electrically connected to the host device (not shown) by control cables 31A and 31B as shown in FIG. Here, as for the connection method between the control cables 31A and 31B and the organic EL element 20, any connection method can be used as long as it is a connection method capable of driving the light emitting unit in the organic EL element 20. A connection method may be used. The light emitting element substrate 21 and the counter substrate 28 include a UV curable adhesive containing a gap agent for separating a space between the light emitting element substrate 21 and the counter substrate 28 at a predetermined interval, and thermosetting. It is bonded by a sealing material 41 such as an adhesive.

  FIG. 4 is a cross-sectional side view of the light emitting device 2A according to the first embodiment (a surface viewed from the direction of the arrow 50 shown in FIG. 3). FIG. 5 is a view showing the structure of the light emitting device 2A according to the first embodiment viewed from the upper surface (the surface facing the rod lens array 2B).

  First, as shown in FIG. 4, the light emitting device 2 </ b> A according to the first embodiment is roughly composed of a light emitting element substrate portion 100 and a counter substrate portion 200.

  Here, the light emitting element substrate unit 100 includes the light emitting element substrate 21 as a lower substrate, the pixel electrode 23 as a first electrode, the HTL 24, the light emitting layer 25, the ETL 26, and the counter electrode as a second electrode. The organic EL element 20 having the electrode 27, and the insulating film 45 that insulates the pixel electrode 23 and the counter electrode 27 around each organic EL element 20. Note that a switching element such as a TFT (not shown) or a TFD (not shown) may be formed on the light emitting element substrate portion 100 as necessary.

  Meanwhile, the counter substrate unit 200 includes the counter substrate 28 and a transparent space forming body 47 provided on the counter substrate 28. As shown in FIG. 4, a liquid storage space 48A is formed in the space forming body 47, and the liquid storage space 48A is filled with a transparent liquid medium 10 to be described later. For this reason, the light of the organic EL element 20 can pass through the liquid medium 10 and be emitted from the light emission region of the counter substrate 28.

  Here, the liquid storage space 48A may be formed by various molding methods such as nanoimprint, injection molding, and photolithography. Further, as shown in FIGS. 4 and 5, the liquid storage space 48 </ b> A is formed at a position facing the organic EL elements 20 constructed in an array on the light emitting element substrate 21 and in the vicinity thereof.

  And the said light emitting element substrate part 100 and the said opposing board | substrate part 200 are adhere | attached with the sealing material 41, as shown in FIG. Here, the sealing material 41 is once applied on the light emitting element substrate 21 so as to surround the organic EL array composed of the plurality of organic EL elements 20, and then bonded to the counter substrate portion 200. At this time, the sealing material 41 may be bonded to the space forming body 47 or directly to the counter substrate 28. In this application, in order to provide a liquid injection hole 42 (see FIG. 5) for injecting the liquid medium 10 later, a portion where the sealing material 41 is not applied is provided.

  As shown in FIG. 4, the liquid medium 10 is also present in a space (boundary space 48B) formed on the boundary surface between the light emitting element substrate portion 100 and the counter substrate portion 200 bonded by the sealing material 41. It is filled.

  By the way, when the liquid medium 10 is injected from the liquid injection hole 42, a method similar to the method of injecting liquid crystal into a normal liquid crystal display element can be used. Hereinafter, this liquid injection process will be specifically described.

  First, a panel in which the light emitting element substrate unit 100 and the counter substrate unit 200 are joined is introduced into the manufacturing furnace, and then the pressure is reduced to less than atmospheric pressure. Thereafter, the panel is lowered or the liquid medium tank filled with the liquid medium is raised, and is brought into contact with the liquid medium so that the liquid injection hole 42 is covered with the liquid medium. Subsequently, the atmospheric pressure is returned to atmospheric pressure. As a result, the pressure of the liquid storage space 48A in the panel becomes a negative pressure relative to the pressure in the manufacturing furnace, and the liquid medium 10 is injected from the liquid injection hole 42 into the liquid storage space 48A. After the liquid medium 10 is filled in the liquid storage space 48A, the light emitting device 2A is taken out from the liquid medium tank so that the filled liquid medium 10 is not spilled, and a sealing material is provided to the liquid injection hole 42. An uncured resin material similar to 41 is applied and then cured to seal the liquid medium 10 as a sealing material 41 ′. In this way, the liquid medium 10 is injected from the liquid injection hole 42 into the liquid storage space 48A and the boundary space 48B, and the liquid injection hole 42 is sealed.

  Hereinafter, the liquid storage space 48A, the boundary space 48B, and the functions of the liquid medium 10 filled in these spaces, which are one of the main features of the light emitting device 2A according to the first embodiment, will be described in detail. explain.

  First, the thermal energy generated in the organic EL element 20 when the light emitting device 2A is driven is transmitted in the following two directions when roughly classified. One is a downward direction shown in FIG. 4, that is, a direction toward the light emitting element substrate portion 100, and the other is an upward direction shown in FIG. 4, that is, a direction toward the counter substrate portion 200.

  Of course, the thermal energy generated in the organic EL element 20 increases the temperature of the peripheral member of the organic EL element 20, and the rate of change in the temperature rises to the size of the heat capacity of the peripheral member. Dependent. That is, the peripheral member having a larger heat capacity has a lower temperature rise value.

  Therefore, in the first embodiment, it is preferable to use a material having a larger heat capacity for the space forming body 47 and the liquid medium 10. Here, various characteristics such as heat capacity of several kinds of materials are shown in FIG.

  Examples of the material of the space forming body 47 include PET (polyethylene terephthalate) having a heat capacity of 1.44 or PC (polycarbonate) having a heat capacity of 1.45 as shown in FIG.

  Further, as the liquid medium 10 filling the liquid storage space 48A and the boundary space 48B, for example, as shown in FIG. 6, Fluorinert (registered trademark) of a fluorine-based inert liquid having a heat capacity of 1.92 or a heat capacity of 1 is used. And a silicone oil that is .62.

  More specifically, examples of the fluorinate include FC-3283 manufactured by 3M, and examples of the silicone oil include KF-96L-1cs manufactured by Shin-Etsu Silicone.

  The silicone oil is a substance that has visible light permeability and is chemically stable. Therefore, the silicone oil has an advantage that there is not much deterioration or deterioration with time due to transmission and irradiation of the light 51 generated in the organic EL element 20.

  Thus, in the first embodiment, the space forming body 47 is formed of a material having a large heat capacity, and the liquid medium 10 having a large heat capacity is filled in the liquid storage space 48A and the boundary space 48B. The heat capacity around the organic EL element 20 is increased. Thereby, the heat | fever of the said organic EL element 20 can be absorbed rapidly, and the temperature rise of the organic EL element 20 can be suppressed low. For this reason, since the volumes of the liquid storage space 48A and the boundary space 48B can be made relatively small, the organic EL element 20 can be cooled without enlarging the light emitting device 2A.

  In addition, as another advantage generated by filling the liquid storage space 48 </ b> A and the boundary space 48 </ b> B with the liquid medium 10, when pressure is applied from the outside to the organic EL element 20, There is an advantage that it is possible to prevent a short circuit caused by pressing the counter electrode. This is because the liquid is a fluid and can be deformed according to the applied external force, so that it is relatively uniformly dispersed.

  Further, from the viewpoint of thermal expansion, the portion where heat is applied expands if it is a solid, so the organic EL element 20 may be pressed by local expansion, but in the first embodiment, Since the liquid medium 10 filled in the liquid storage space 48A and the boundary space 48B is a fluid and is easily heated uniformly, pressure on the organic EL element 20 due to thermal expansion is also uniformly applied. The organic EL element 20 is hardly damaged.

  Hereinafter, as an example of active matrix driving, one configuration example of a driving circuit unit for performing light emission control of the organic EL element 20 by a signal voltage gradation control method in which two transistors are provided in each pixel is described with reference to FIG. To explain. The drive circuit section is not a feature of the present invention and will be described briefly.

  As shown in FIG. 7, the counter electrode 27 is a single common electrode common to the plurality of organic EL elements 20. In addition, for each pixel, an organic EL element drive circuit 99 including a selection transistor 101, a drive transistor 103, an organic EL element 20 connected to the selection transistor 103, and a capacitor 105 for data storage includes an organic EL element drive circuit 99. A light emitting element substrate 21 is provided along the EL array.

  Both the selection transistor 101 and the drive transistor 103 are, for example, n-channel amorphous silicon TFTs. The drain of the selection transistor 101 is connected to the signal line 107, and the gate of the selection transistor 101 is connected to the scanning line 109. The drain of the driving transistor 103 is connected to the power supply line 111, and the source of the selection transistor 101 and the gate of the driving transistor 103 are connected via a contact hole 110. The counter electrode 27 is fixed at, for example, 0 (V), and the pixel electrode 23 is electrically connected to the source electrode of the driving transistor 103. The capacitor 105 is provided between the gate electrode and the source electrode of the driving transistor 103. The signal line 107, the scanning line 109, and the power supply line 111 are routed to the control cables 31A and 31B and connected to external circuits, respectively. With such a structure, only the organic EL element 20 which is a thin film layer in a region sandwiched between the counter electrode 27 and the pixel electrode 23 emits light upon receiving voltage application (current supply).

  As described above, according to the first embodiment, it is possible to provide a light emitting device that can efficiently remove heat generated in the organic EL element 20 due to light emission in a short time.

  Specifically, the space forming body 47 is formed of a material having a large heat capacity, and the liquid medium 10 having a large heat capacity is filled in the liquid storage space 48A and the boundary space 48B. By increasing the heat capacity, the temperature rise in the organic EL element 20 can be kept low.

  In the liquid medium 10, when pressure is applied from the outside to the organic EL element 20, the liquid medium 10 functions as a buffer material, so that the pixel electrode 23 and the counter electrode 27 are pressed. Can prevent short circuit.

  When the light emitting device according to the first embodiment is applied to an exposure unit in a printing apparatus or an image forming apparatus, the following effects can be obtained.

  That is, since the organic EL element 20 has a good heat dissipation efficiency and can dissipate heat in a short time, it is possible to drive with high brightness by increasing the applied voltage, so that the printing speed can be increased.

  Moreover, since the deterioration of the organic EL element 20 itself can be reduced by suppressing the heat generation in the organic EL element 20, the device life and the printing life of the light emitting device 2A can be extended. Further, luminance unevenness caused by the heat generation of the organic EL element 20 can be reduced, so that the print image quality can be stabilized.

  Furthermore, since the heat capacity of the organic EL element 20 can be increased with respect to the size of the light emitting device, there is thermal stability, and the exposed portion can be downsized or densified.

[Second Embodiment]
Next, a light emitting device according to a second embodiment of the invention will be described. In order to focus on the features of the light emitting device according to the second embodiment, differences between the light emitting device according to the first embodiment and the light emitting device according to the second embodiment will be mainly described. The same points are omitted as appropriate.

  FIG. 8 is a side sectional view of the light emitting device according to the second embodiment. FIG. 9 is a view showing a structure of the light emitting device according to the second embodiment viewed from above.

  In the light emitting device 2A according to the second embodiment, as shown in FIGS. 8 and 9, the liquid storage space 48A is formed to have a lens structure. That is, the lens structure portion 43 is provided in the space forming body 47 so that the liquid storage space 48A has a desired shape. Here, the lens structure portion 43 is provided on the light emitting element substrate 21 so as to face the organic EL elements 20 constructed in an array on a one-to-one basis.

  By using the light emitting device 2A having such a structure, the light emitted from the organic EL element 20 is condensed by the lens structure portion 43 provided in the liquid storage space 48A and is directed to the rod lens array 2B. It can be made incident.

  For example, when the fluorine-based inert liquid (refractive index: 1.28) shown in FIG. 6 is used as the liquid medium 10 and the PC (refractive index: 1.58) shown in FIG. That is, when the refractive index of the liquid medium 10 is lower than the refractive index of the space forming body 47, the lens structure portion 43 is formed in a convex shape in the space forming body 47 so that the liquid storage space 48A has a concave lens shape. When the refractive index of the liquid medium 10 is higher than the refractive index of the space forming body 47, the lens structure portion 43 may be formed in a concave shape in the space forming body 47 so that the liquid storage space 48A has a convex lens shape. The liquid storage space 48A has a concave lens structure with respect to the emission direction as shown in FIG. 8, so that the diffused light from the organic EL element 20 is condensed as shown by the arrow 50 in FIG. The direction of can be narrowed down.

  That is, by designing the lens structure portion 43 according to the refractive index of the liquid medium 10, it is possible to control the extraction efficiency and directivity of the light emitted from the organic EL element 20.

  As described above, according to the light emitting device according to the second embodiment, the same effect as that of the light emitting device according to the first embodiment can be obtained, and the light extraction efficiency and directivity can be controlled. A light-emitting device can be provided.

  It should be noted that the organic EL element drive circuit 99 described above may be provided.

[Third Embodiment]
Next, a light emitting device according to a third embodiment of the invention will be described. In order to focus on the features of the light emitting device according to the third embodiment, only the differences between the light emitting device according to the first embodiment and the light emitting device according to the third embodiment will be mainly described. The same points are omitted as appropriate.

  FIG. 10 is a side sectional view of the light emitting device 2A according to the third embodiment. FIG. 11 is a view showing a structure of the light emitting device 2A according to the third embodiment as viewed from above.

  In the light emitting device 2A according to the third embodiment, as shown in FIGS. 10 and 11, a portion of the liquid storage space 48A that does not block emission of light emitted by the organic EL element 20 is sputtered or vacuumed. A heat dissipation film 49 having excellent thermal conductivity such as metal formed by patterning using a metal mask by vapor deposition or the like is provided. The heat radiation film 49 has a radiation surface 49A extending to the outside of the sealing material 41, and the radiation surface 49A is exposed to the outside of the light emitting device 2A. The heat dissipation film 49 is not particularly limited as long as it has a higher thermal conductivity than that of the space forming body 47, but may include copper (thermal conductivity 398 W / m · K) or aluminum (thermal conductivity 237 W / m · K). preferable.

  With the light emitting device 2A having such a structure, the heat energy is quickly transferred from the liquid medium 10 storing the heat energy generated in the organic EL element 20 to the peripheral structure portion by the heat dissipation film 49. Heat can be quickly released from the exposed radiation surface 49. In general, since the heat transfer coefficient of a metal material has a value close to 1000 times that of a resin material, the heat radiating film 49 can quickly diffuse the heat generated in the organic EL element 20 to surrounding structures.

  Further, as shown in FIG. 10 and FIG. 11, the heat radiation film 49 is continuously formed up to a portion adjacent to the external space of the light emitting device 2A, so that it is stored in the liquid storage space 48A. The generated thermal energy can be transmitted to the external space of the light emitting device 2A.

  As described above, according to the third embodiment, the same effect as the light emitting device according to the first embodiment can be obtained, and the liquid storage space 48A and the boundary generated by the organic EL element 20 can be produced. It is possible to provide a light emitting device that can quickly dissipate heat stored in the space 48B.

  It should be noted that the organic EL element drive circuit 99 described above may be provided.

[Fourth Embodiment]
Next, a light emitting device according to a fourth embodiment of the invention will be described. The light emitting device 2A of the fourth embodiment mainly includes a space forming body 47 having the lens structure 43 in the second embodiment and a heat dissipation film 49 having the radiation surface 49A in the third embodiment.

  FIG. 12 is a side sectional view of the light emitting device 2A according to the fourth embodiment. FIG. 13 is a diagram showing a structure of the light emitting device 2A according to the fourth embodiment as viewed from above.

  Specifically, in the light emitting device 2A according to the fourth embodiment, as shown in FIGS. 12 and 13, the lens structure portion 43 is provided in the liquid storage space 48A, and the liquid storage space 48A is provided. Among them, a heat radiating film 49 formed by patterning using a metal mask by sputtering, vacuum deposition or the like is provided at a portion that does not block the emission of light emitted by the organic EL element 20.

  As described above, according to the fourth embodiment, it is possible to provide a light emitting device that exhibits the same effects as the light emitting devices according to the second embodiment and the third embodiment.

  As mentioned above, although this invention was demonstrated based on 1st Embodiment thru | or 4th Embodiment, this invention is not limited to embodiment mentioned above, A various deformation | transformation and application are within the range of the summary of this invention. Of course it is possible.

  For example, in the first to fourth embodiments, the counter substrate unit 200 has a two-layer structure in which the space forming body 47 is provided on the counter substrate 28. However, the counter substrate unit is made of a single material. Of course, 200 may be configured.

  Furthermore, in the first to fourth embodiments, a top emission type organic EL element is assumed. However, the first to fourth embodiments are also applied to a bottom emission type organic EL element. Of course you can. Even in the bottom emission type organic EL element, it is desirable that the liquid storage space 48 </ b> A is disposed between the organic EL element 20 and the counter substrate 28 in order to cool the liquid medium 10 in contact with the organic EL element 20. When forming the lens structure portion 43, the space formation body 47 is provided between the organic EL element 20 and the light emitting element substrate 21, and the lens structure portion 43 and the liquid storage space 48 </ b> A are formed in the space formation body 47. preferable.

  The above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

1 is a diagram illustrating a configuration example of a printing apparatus using a light emitting device according to a first embodiment of the present invention. The figure explaining the basic structure of an organic electroluminescent light-emitting body. FIG. 3 is a diagram schematically showing an appearance of an exposure unit of a printing apparatus using the light emitting device according to the first embodiment of the invention. FIG. 3 is a side cross-sectional view of the light emitting device according to the first embodiment of the present invention. The figure which shows the structure which looked at the said light-emitting device which concerns on 1st Embodiment of this invention from the upper surface. The figure which shows various characteristics, such as a heat capacity, about the material used as a space formation body or a liquid medium. The figure which shows the example of 1 structure of the drive circuit part for performing light emission control of an organic electroluminescent light emitting layer. Side surface sectional drawing of the said light-emitting device which concerns on 2nd Embodiment of this invention. The figure which shows the structure which looked at the said light-emitting device which concerns on 2nd Embodiment of this invention from the upper surface. Side surface sectional drawing of the said light-emitting device which concerns on 3rd Embodiment of this invention. The figure which shows the structure which looked at the said light-emitting device which concerns on 3rd Embodiment of this invention from the upper surface. Side surface sectional drawing of the said light-emitting device which concerns on 4th Embodiment of this invention. The figure which shows the structure which looked at the said light-emitting device which concerns on 4th Embodiment of this invention from the upper surface.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 3 ... Charging roller, 4 ... Eraser light source photoconductor, 5 ... Cleaning member, 6 ... Developing device, 6a ... Developing roller, 7 ... Printing paper, 8 ... Transfer roller, 9 ... Fixing roller, 10 ... Liquid medium, 11 ... Conveying belt, 20, 20A ... Organic EL light emitting layer, 21 ... Light emitting element substrate, 23 ... Pixel electrode, 24 ... Hole transport layer, 25 ... Light emitting layer, 26 ... Electron transport layer, 27 ... Counter electrode 28 ... Counter substrate, 30 ... EL element, 31A, 31B ... Control cable, 33 ... Light emitting area, 41 ... Sealing material, 42 ... Liquid injection hole, 43 ... Lens structure, 45 ... Insulating film, 47 ... Space formation 48A ... Liquid storage space 48B ... Boundary space 49 ... Heat dissipation film 100 ... Light emitting element substrate part 101 ... Switch TFT 103 ... Current drive TFT 10 ... capacitors, 107 ... data line, 109 ... scan line, 111 ... current supply line, 200 ... counter substrate portion.

Claims (9)

A light emitting element substrate in which a plurality of light emitting elements are arranged at predetermined intervals;
A counter substrate provided facing the substrate;
A medium storage space interposed between the light emitting element and a light emitting region from which light of the light emitting element is emitted;
A light-emitting device comprising:   The light emitting device according to claim 1, wherein a heat capacity of a medium filling the medium storage space is at least larger than a heat capacity of the counter substrate.   The light-emitting device according to claim 1, wherein the medium storage space is formed in a lens shape that collects light of the light-emitting element. A substrate on which a plurality of light emitting elements are arranged at a predetermined interval;
A counter substrate provided facing the substrate;
A medium storage space interposed between the light emitting element and a light emitting region from which light of the light emitting element is emitted;
A lens structure that collects light from the light emitting element;
A light-emitting device comprising:   5. The heat dissipation film is formed in a portion where the medium storage space is formed in a portion that does not block light emitted from the light exit surface of the light emitting element. Light-emitting device.   The light-emitting device according to claim 4, wherein the medium is a liquid medium or a gas medium.   The light-emitting device according to claim 5, wherein the heat dissipation film is continuously formed up to a location where the counter substrate is adjacent to the outside of the light-emitting device. A light-emitting element substrate in which a plurality of light-emitting elements are constructed in an array at predetermined intervals;
A counter substrate including a lens structure portion formed in a lens shape to collect light emitted from a light emitting region in the light emitting element;
A seal member that bonds the light emitting element substrate and the counter substrate so that the light emitting region of the light emitting element and the lens structure portion are adjacent to each other;
Comprising
The boundary region between the substrate and the counter substrate bonded by the sealing member and the lens structure portion are filled with a liquid medium for storing a medium having a larger heat capacity than any member in contact with the light emitting element. A light-emitting device characterized by being made.   A printing apparatus comprising the light emitting device according to claim 1.

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