JP4712293B2 - projector - Google Patents

Description

  The present invention relates to a light emitting device, particularly a projector, having a semiconductor laser using an electroluminescent material in each pixel.

  Semiconductor lasers have the advantage that laser oscillators can be dramatically reduced in size and weight compared to other gas or solid-state lasers, and have been put into practical use in various fields. The oscillation wavelengths of semiconductor lasers range from blue to infrared, and many semiconductor lasers that are in practical use generally have an oscillation wavelength in the infrared region. In recent years, there have been many studies on the practical application of semiconductor lasers having an oscillation wavelength in the visible region. From this trend, laser light is oscillated using an electroluminescent material that can obtain luminescence by applying an electric field. Attention is being focused on laser oscillators (organic semiconductor lasers) that can be used. Since an organic semiconductor laser can obtain laser light having a wavelength in the visible region and can be manufactured on an inexpensive glass substrate, various uses are expected. For example, Patent Document 1 below describes an organic semiconductor laser having a peak wavelength λ of 510 nm.

JP 2000-156536 A (page 11)

  By the way, a projector using a liquid crystal element as an optical modulator has a problem that power consumption increases because it is necessary to always turn on the light source regardless of the gradation level displayed by the pixel. Therefore, Patent Document 2 described below describes a technique for forming a projector using a light emitting diode as a pixel. By using a light-emitting element that can obtain visible light, such as a light-emitting diode, for a pixel, it is not necessary to use a high-intensity light source such as a xenon lamp or a halogen lamp. Therefore, it is possible to reduce the size of the device itself.

JP-A-11-32278

  In a projector using a light emitting element as described above, when light emitted like a light emitting diode is natural light, an optical system such as a lens array is used to emit light in order to further increase the image contrast while suppressing power consumption. It is effective to control the optical path of light emitted from the element. However, in general, the optical system is relatively bulky and expensive, which can prevent the miniaturization of the projector and increase the cost. Further, as the optical system becomes more complicated, operations such as adjustment of the optical system at the time of maintenance and alignment between the optical system and the light emitting element become more complicated, and resistance to physical impact becomes lower. Therefore, it is desirable that the optical system used in the projector is simpler.

  Therefore, in order to simplify the optical system, a semiconductor laser capable of obtaining laser light can be used in the projector instead of the light emitting diode capable of obtaining natural light. The use of laser light makes it easier to control the optical path inside the projector than in the case of natural light, so the optical system can be simplified to some extent, and the contrast can be increased while reducing power consumption. .

  Note that laser light oscillated from a semiconductor laser generally has a lower directivity than other lasers and tends to diffuse. If the directivity of the laser light oscillated from the semiconductor laser can be increased, the optical path can be controlled more easily, and the optical system for controlling the optical path can be further simplified. However, since it becomes necessary to newly add an optical system for improving directivity, it is difficult to simplify the entire optical system as a result.

  In addition, since the semiconductor laser uses a single crystal semiconductor, it is difficult to optimize the structure of the optical resonator in order to increase the oscillation efficiency. Therefore, it is difficult to further improve contrast while suppressing power consumption.

  In view of the above-described problems, an object of the present invention is to provide a projector that can realize further simplification of the optical system, or a projector that can realize higher contrast while suppressing power consumption.

  The projector of the present invention uses a panel having an organic semiconductor laser in each pixel, and displays an image by projecting laser light emitted from the panel onto a screen. In the present invention, the organic semiconductor laser (hereinafter referred to as a laser element) has any one of the following first to third configurations.

  First, the first configuration will be described. The laser element having the first configuration is formed by forming a concave portion or a convex portion in a layer such as a substrate or a base film for supporting a light emitting element using an electroluminescent material, or a layer covering the light emitting element. The function as an optical system is added, and the directivity of the laser beam obtained by the light emitting element is enhanced.

  The light-emitting element includes a first electrode, a second electrode, and a light-emitting layer provided between the two electrodes, and an electroluminescent material contained in the light-emitting layer functions as a laser medium. One of the first electrode and the second electrode is an anode, and the other is a cathode. Note that a hole injection layer, a hole transport layer, and the like may be provided between the light emitting layer and the anode, and an electron injection layer, an electron transport layer, and the like may be provided between the light emitting layer and the cathode. In this case, all layers provided between the anode and the cathode including the light emitting layer are called electroluminescent layers. In some cases, the layer constituting the electroluminescent layer contains an inorganic compound.

  In the laser element having the first configuration, the optical resonator is a parallel plane system, and two reflecting materials having a plane for reflecting and resonating light are used. Specifically, an optical resonator can be formed by using a part of the first electrode and the second electrode as a reflecting material. Note that it is not always necessary to use a part of the first electrode and the second electrode as the reflecting material for forming the optical resonator. For example, a separately formed film for reflecting light (reflection film) may be used as the reflecting material. In addition, a layer other than the light emitting layer included in the electroluminescent layer, for example, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, or the like reflects light generated in the light emitting layer to form an optical resonator. Also good. The optical axis of the oscillated laser beam intersects the concave portion or convex portion.

  Next, the second configuration will be described. The laser element having the second configuration lowers the threshold of pumping energy necessary for starting oscillation by giving a curvature to the reflecting material for reflecting the stimulated emission light and suppressing diffraction loss in the optical resonator. As a result, the oscillation efficiency of the organic semiconductor laser is increased.

  Note that in the laser element having the second structure, the first electrode and the second electrode of the light emitting element may be used as the reflecting material for resonating light, or a reflecting material having a recess is separately formed. The light generated in the electroluminescent layer may be caused to resonate with either the first electrode or the second electrode and the reflective material. In addition, a layer other than the light emitting layer included in the electroluminescent layer, for example, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, or the like reflects light generated in the light emitting layer to form an optical resonator. Also good. The optical axis of the oscillated laser beam intersects the concave portion.

  In addition, the optical resonator included in the laser element having the second configuration may be a hemispherical system in which one of the two reflecting materials has a curved surface and the other has a flat surface, and the two reflecting materials have both curved surfaces. A confocal system, a concentric system, or a spherical system may be used. In the present invention, a stable resonator can be formed by adjusting the curvature radius r and the length of the resonator length L, and diffraction loss can be suppressed.

  Next, the third configuration will be described. In the laser element having the third configuration, one of the reflecting materials for reflecting the stimulated emission light has a curvature, and the two reflecting materials face each other so that an unstable resonator is formed. A laser beam having a high directivity is obtained near a single mode. The center of curvature of the reflective material may be provided on the side on which the other reflective material is formed, or may be provided on the opposite side to the other reflective material.

  In the laser element having the third structure, two separately formed reflecting materials may be provided in addition to the light emitting element, but one or both of the electrodes of the light emitting element may be used as the reflecting material. Alternatively, a layer other than the light-emitting layer included in the electroluminescent layer, for example, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, or the like is used as a reflective material, and light generated in the light-emitting layer is reflected, so May be formed. Laser light is oscillated by resonating light emitted from the electroluminescent material by the two reflecting materials. The optical axis of the oscillated laser beam intersects the convex portion or the concave portion.

  Further, the optical resonator included in the laser element of the present invention is an unstable resonator, and the length of the curvature radius r and the length of the resonator L are adjusted, or the position of the center of curvature of the unevenness of the reflector is controlled. Therefore, an unstable resonator can be formed and directivity can be improved.

  The projector of the present invention can enhance the directivity of the laser light oscillated from the laser element by the first configuration described above. Since a part of the layer functions as an optical system, it is possible to avoid the trouble of adjusting the optical system at the time of maintenance and aligning the optical system and the laser element, unlike when an optical system is provided separately. And the resistance to physical impact can be increased.

  Note that, unlike an organic semiconductor laser, a semiconductor laser using a single crystal semiconductor forms a curved surface on an electrode functioning as a reflecting material, or forms an active region that is a laser medium on a reflecting material having a curved surface. This is difficult in the manufacturing process. In addition, when a reflective material having a curved surface formed separately is attached after forming an active region that is a laser medium, position control between the two reflective materials and the active region must be performed on the order of several tens of nanometers. Therefore, the manufacturing process becomes complicated. However, in the case of an organic semiconductor laser, it is relatively easy to form a curved surface on an electrode functioning as a reflective material, and to form a light emitting element on a reflective material having a curved surface, as compared to a semiconductor laser. Therefore, it is possible to relatively easily control the position of the two reflecting materials and the active region on the order of several tens of nanometers depending on the film thickness of each layer.

  Therefore, unlike the case of the semiconductor laser using a single crystal semiconductor, the projector according to the present invention has one of two reflecting materials having a curved surface and a stable resonator. A laser element can be manufactured relatively easily by using a light emitting element. The stable resonator can increase the oscillation efficiency, and can obtain a high-contrast image with low power consumption.

  Therefore, the projector according to the present invention can increase the oscillation efficiency of single-mode laser light by the above-described third configuration. Therefore, the directivity of laser light can be increased without providing an optical system separately. Unlike the case where an optical system is separately provided, it is possible to avoid the trouble of adjusting the optical system at the time of maintenance and the alignment between the optical system and the laser element, and the resistance of the laser element to physical shock can be avoided. Can be increased.

  First, the configuration of the projector of the present invention using the laser element having the first configuration will be described.

  FIG. 1A briefly shows the configuration of the projector of the present invention. The projector of the present invention includes a panel 100 in which laser elements are arranged in a matrix, and an optical system (projection optical system) 101 for projecting laser light emitted from the panel 100 onto a screen. In the case of a front type projector, the screen is separated and independent. In the case of a rear type projector, in addition to the above configuration, the screen is provided in the cabinet of the projector.

  The laser element having the first structure used for the panel 100 includes a light-emitting element using an electroluminescent material and a layer for supporting the light-emitting element to which a function as an optical system is added. And a layer covering the light-emitting element.

  Next, FIG. 1B illustrates a top view of the panel 100 as an example. FIG. 1C is a cross-sectional view taken along line A-A ′ in FIG.

  In the panel shown in FIGS. 1B and 1C, a film (a planarization layer) 104 is formed on a substrate 103 having a plurality of recesses 102 so as to fill the plurality of recesses 102. The substrate 103 has a refractive index lower than that of the planarization layer 104, and the planarization layer 104 has a light-transmitting property. Note that FIG. 1C illustrates an example in which the planarization layer 104 is formed using one layer; however, the planarization layer 104 may be formed using a plurality of layers. However, in this case, the refractive index of the substrate 103 is set lower than the refractive index of the layer closest to the substrate 103 in the planarization layer 104.

  A reflective film 105 used as a reflective material is formed on the planarization layer 104. The reflective film 105 can reflect light emitted from the light-emitting element and can be formed using an insulating material. For example, a film in which insulating films having different refractive indexes such as silicon oxide, silicon nitride, and titanium oxide are alternately stacked may be used.

  An electrode 106 is formed on the reflective film 105 so as to overlap the plurality of recesses 102. Note that in FIGS. 1B and 1C, the electrode 106 has a light-transmitting property and the reflective film 105 is used as a reflective material; however, the present invention is not limited to this mode. The electrode 106 formed of a material that reflects light without providing the reflective film 105 may be used as a reflective material.

  In addition, electroluminescent layers 107 a to 107 c corresponding to three colors of red (R), green (G), and blue (B) are formed on the electrode 106 so as to overlap with the plurality of recesses 102. In FIGS. 1B and 1C, the electroluminescent layers 107a to 107c are formed separately, but may be formed so as to partially overlap each other. An electrode 108 is formed on the electroluminescent layers 107 a to 107 c so as to overlap with the plurality of recesses 102.

  One of the electrodes 106 and 108 is an anode and the other is a cathode. 1B and 1C illustrate an example in which the electrode 106 is an anode and the electrode 108 is a cathode, the electrode 106 may be a cathode and the electrode 108 may be an anode.

  In FIG. 1B and FIG. 1C, the plurality of electrodes 108 and the plurality of electrodes 106 overlap each other with the electroluminescent layers 107a to 107c interposed therebetween. The overlapping portion corresponds to the light emitting element 109, and each light emitting element 109 is located in the recess 102. In FIGS. 1B and 1C, the electrode 108 is formed using a material that reflects light, and the electrode 108 is used as a reflective material; however, the present invention is not limited to this mode. For example, the electrode 108 may be formed using a light-transmitting material, and a reflective film functioning as a reflective material may be provided over the electrode 108.

  Note that the substrate 103 has a curved surface in the concave portion 102, and the center of curvature of the curved surface exists on the light emitting element 109 side.

  The panel 100 is a passive matrix, and by applying a forward bias voltage between the selected electrodes 106 and 108, current is supplied to the electroluminescent layers 107a to 107c, causing the electroluminescent layers 107a to 107c to emit light. be able to. Then, the emitted light resonates between two reflecting materials, here, the reflecting film 105 functioning as a reflecting material and the electrode 108, whereby the laser light is oscillated.

  Note that the transmittance of the reflective film 105 is, for example, about 5 to 70%, and the transmittance of the electrode 108 is lower than that of the reflective film 105. With the above structure, the stimulated emission light generated in the electroluminescent layers 107a to 107c can resonate between the reflective film 105 functioning as a reflective material and the electrode 108, and the laser light can be oscillated from the reflective film 105 side.

  The laser light oscillated from the reflective film 105 side toward the concave portion 102 diverges to some extent. However, by reflecting at the concave portion 102 of the substrate 103, the divergence angle is suppressed and the directivity is increased. In order to suppress the divergence angle, the focal length of the recess 102 may be optically designed in accordance with the divergence angle of the laser beam irradiated to the recess 102.

  In FIGS. 1B and 1C, the laser element has a recess for reflecting the laser beam, but may have a projection for refracting the laser beam. Moreover, you may make it provide both the said recessed part and a convex part. In any case, both the concave portion and the convex portion described above have the center of curvature on the light emitting element side.

  Note that in FIGS. 1B and 1C, electroluminescent layers corresponding to R, G, and B are provided, but in the case of performing monochrome display, only one electroluminescent layer is required.

  Next, the configuration of the projector according to the present invention using the laser element having the second configuration will be described.

  Similar to the projector shown in FIG. 1A, the projector itself has a panel in which laser elements are arranged in a matrix and a projection optical system.

In FIG. 2 (A), a top view of a panel having a laser device of the second configuration, as an example. Also in FIG. 2 (B), a cross sectional view taken along A-A 'in FIG. 2 (A).

FIG. 2 (A), the panel shown in FIG. 2 (B), on a substrate 201 having a plurality of recesses 200, the electrode 203 so as to overlap with each of the plurality of recesses 200 are formed. The electrode 203 is made of a material that reflects light and functions as a reflector.

Electroluminescent layers 204 a to 204 c corresponding to the three colors of red (R), green (G), and blue (B) are formed on the electrode 203 so as to overlap with the plurality of recesses 200. Note FIG. 2 (A), the in FIG. 2 (B), the although the electroluminescent layer 204a~204c are formed separately, may be formed so as to partially overlap each other. An electrode 205 is formed on the electroluminescent layers 204a to 204c so as to overlap with the plurality of recesses 200.

One of the electrodes 203 and 205 is an anode and the other is a cathode. FIG. 2 (A), the anode of FIG. 2 (B) in the electrode 203, an example in which the electrode 205 and the cathode, the electrode 203 cathode may be an electrode 205 as an anode.

In addition FIG. 2 (A), the FIG. 2 (B), the although to form an electroluminescent layer 204a~204c a plurality of layers including a light emitting layer, even electroluminescent layer 204a~204c is include only luminescent layer good. Further, planarization can be easily performed by using a polymer-based electroluminescent material capable of forming a film by a spin coating method for any of the layers included in the electroluminescent layer. In the case where the electroluminescent layers 204a to 204c are formed of a plurality of layers, a layer provided between the electrode 203 and the light emitting layer among the electroluminescent layers is formed so that the surface thereof is planarized. For example, when the electrode 203 is an anode, a hole injection layer or a hole transport layer whose surface is planarized may be formed of a polymer electroluminescent material such as PEDOT. For example, when the electrode 203 is a cathode, the surface of the electron injection layer or the electron transport layer is formed to be flat.

FIG. 2 (A), the in FIG. 2 (B), the a plurality of rows of electrodes 203, a plurality of rows of electrodes 205, which sandwich the electroluminescent layer 204a-204c, overlapped to be crossed between. The overlapping portion corresponds to the light emitting element 206, and each light emitting element 206 is located in the recess 200.

FIG. 2 (A), the panel shown in FIG. 2 (B) is a passive matrix, by applying a forward bias voltage between the electrodes 203, the electrode 205 is selected, the current to the electroluminescent layer 204a~204c When supplied, the electroluminescent layers 204a to 204c can emit light. Then, the emitted light resonates between two reflecting materials, here, the electrode 203 and the electrode 205 functioning as a reflecting material, so that laser light is oscillated.

  Then, the transmittance of the electrode 205 is set to about 5 to 70%, and the transmittance of the electrode 203 is made lower than that of the electrode 205. With the above structure, the stimulated emission light generated in the electroluminescent layers 204a to 204c can resonate between the electrode 203 and the electrode 205 functioning as a reflecting material, and the laser light can be oscillated from the electrode 205 side.

Note that the electrode 203 has a curved surface in the concave portion 200 of the substrate 201, and the center of curvature of the curved surface exists on the electrode 205 side. And FIG. 2 (A), the in FIG. 2 (B), the surface of the electrode 205 side of the electroluminescent layer 204a~204c is flattened, it is formed on the planarized electroluminescent layer 204a~204c electrode 205 Has a plane. Thus, the two electrodes 203 and 205 functions as a reflective material, one is a curved surface, since the other has a flat surface, FIG. 2 (A), the panel shown in FIG. 2 (B) corresponding to a half spherical system. And FIG. 2 (A), the panel shown in FIG. 2 (B), the optical resonator is stable type resonator, the distance L between the electrodes 203 and the electrodes 205 corresponding to the cavity length, the focal length f , F ≧ L / 2 is satisfied. The cavity length is assumed to correspond to the distance between the two reflectors on the extension of the optical path of the oscillated laser beam. With the above structure, the oscillation efficiency of laser light oscillated from the electrode 205 side can be increased.

Note that in FIG. 2 (A), the FIG. 2 (B), the one of the two reflectors are curved, while the other is a semi-spherical surface system having a planar, confocal system with two curved reflective material are both co It may be a heart system or a spherical system. In the case of a hemispherical system, a convex portion that can refract laser light and enhance directivity may be provided so as to overlap the light emitting element.

The FIG. 2 (A), the in FIG. 2 (B), the by using a substrate 201 having a recess 200, but are formed an electrode 203 having a curved surface, the present invention is not limited to this structure. You may form the recessed part which has a curved surface directly in the electrode 203, without forming on the layer which has a recessed part.

The FIG. 2 (A), the in FIG. 2 (B), the is used an electrode of the light-emitting element as a reflector, the present invention is not limited to this structure. A film or a substrate other than the electrodes may be used as the reflecting material. In this case, the electrode is formed using a light-transmitting material.

In addition FIG. 2 (A), the FIG. 2 (B), R, G , is provided with the light emitting layer corresponding to B, and to display a monochrome electroluminescent layer may be one.

  Next, the configuration of the projector of the present invention using the laser element having the third configuration will be described.

  Similar to the projector shown in FIG. 1A, the projector itself has a panel in which laser elements are arranged in a matrix and a projection optical system.

In FIG. 3 (A), a top view of a panel having a laser device of the third configuration, as an example. Further in FIG. 3 (B), a cross sectional view taken along A-A 'in FIG. 3 (A).

FIG. 3 (A), the panel shown in FIG. 3 (B), on a substrate 301 having a plurality of protrusions 300, the reflective layer 302 so as to overlap with the plurality of protrusions 300 are formed. The convex portion 300 has a curved surface, and the center of curvature of the curved surface exists on the side of the substrate 301 opposite to the light emitting element 102. Further in FIG. 3 (A), the FIG. 3 (B), the is used a substrate 301 having a convex portion 300 may form a convex portion using different film from the substrate on a flat substrate.

  The reflective film 302 can reflect light emitted from the light-emitting element and can be formed using an insulating material. For example, a film in which insulating films having different refractive indexes such as silicon oxide, silicon nitride, and titanium oxide are alternately stacked may be used.

  An electrode 303 is formed on the reflective film 302 so as to overlap the plurality of convex portions 300. The electrode 303 is formed using a light-transmitting material. The reflective film 302 formed on the substrate 301 has a curved surface formed by the convex portion 300 of the substrate 301, and the center of curvature of the curved surface exists on the substrate 301 side.

Then, electroluminescent layers 304 a to 304 c corresponding to three colors of red (R), green (G), and blue (B) are formed on the electrode 303 so as to overlap the plurality of convex portions 300. Note FIG. 3 (A), the In FIG. 3 (B), although the electroluminescent layer 304a~304c are formed separately, may be formed so as to partially overlap each other. An electrode 305 is formed on the electroluminescent layers 304 a to 304 c so as to overlap the plurality of convex portions 300.

One of the electrodes 303 and 305 is an anode and the other is a cathode. FIG. 3 (A), the FIG. 3 (B) in the electrode 303 anode, an example in which the electrode 305 and the cathode, the electrode 303 cathode may be an electrode 305 as an anode.

In FIG. 3 (A), FIG. 3 (B), the a plurality of rows of electrodes 303, a plurality of rows of electrodes 305, which sandwich the electroluminescent layer 304a to 304c, overlapped to be crossed between. The overlapping portion corresponds to the light emitting element 306, and each light emitting element 306 is located on the convex portion 300.

FIG. 3 (A), the panel shown in FIG. 3 (B) is a passive matrix, by applying a forward bias voltage between the electrodes 303, the electrode 305 is selected, the current to the electroluminescent layer 304a~304c The supplied electroluminescent layers 304a to 304c can emit light. Then, the emitted light resonates between two reflecting materials, here, the reflecting film 302 functioning as a reflecting material and the electrode 305, whereby laser light is oscillated.

  Then, the transmittance of the electrode 305 is set to about 5 to 70%, and the transmittance of the electrode 303 is set lower than that of the electrode 305. With the above structure, the stimulated emission light generated in the electroluminescent layers 304a to 304c can resonate between the reflective film 302 functioning as a reflective material and the electrode 305, and laser light can be oscillated from the electrode 305 side.

  In the panel having the third configuration, the optical resonator formed by the reflective film 302 and the electrode 305 is an unstable resonator, so that the directivity of laser light oscillated from the electrode 305 side is increased. In the case of an unstable resonator, the distance L between the reflective film 302 and the electrode 305 corresponding to the resonator length and the focal length f (f <0) of the curved surface of the reflective film 302 satisfy f <L / 2. . Note that since twice the focal length f corresponds to the radius of curvature r, it can be said that r <L. The cavity length is assumed to correspond to the distance between the two reflectors on the extension of the optical path of the oscillated laser beam. With the above structure, it becomes easy to obtain single-mode laser light out of laser light oscillated from the electrode 305 side, so that the oscillation efficiency of the single-mode laser light can be increased and directivity is increased.

  When the electrode 305 has a curved surface and the center of curvature of the curved surface exists on the reflective film 302 side, in order to form an unstable resonator, the resonator length L and the curvature radius r1 (r1) of the reflective film 302 <0) The radius of curvature r2 (r2> 0) of the electrode 305 needs to satisfy at least one of the following two expressions.

Note FIG. 3 (A), the In FIG. 3 (B), has been described embodiment to increase the oscillation efficiency of the laser beam of single mode using a reflector having a convex portion may be a reflective material having a recess . Further in FIG. 3 (A), the FIG. 3 (B), the although the substrate 301 has been described the configuration having irregularities, on a flat substrate, may be formed irregularities using different film from the substrate.

Also FIG. 3 (A), the In FIG. 3 (B), is used the electrode of the light-emitting element as a reflector, the present invention is not limited to this structure. A film or a substrate other than the electrodes may be used as the reflecting material. In this case, the electrode is formed using a light-transmitting material.

Further in FIG. 3 (A), the FIG. 3 (B), R, G , is provided with the light emitting layer corresponding to B, and to display a monochrome electroluminescent layer may be one.

  Note that the panel shown in FIGS. 1 to 3 resonates light by using two electrodes included in the light-emitting element and a separately provided reflecting material, but the present invention is not limited to this configuration. Forms a curved surface in a layer other than the light emitting layer included in the electroluminescent layer, for example, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, etc., and reflects light generated in the light emitting layer to form an optical resonator You may do it.

  In this embodiment, a configuration of the projector of the present invention, which is different from that in FIG.

  FIG. 4A shows the configuration of the projector of this embodiment. In FIG. 4A, 401 is a panel in which laser elements are arranged in a matrix, and 402 is a projection optical system for controlling the optical path of laser light emitted from the panel 401 and projecting it onto the screen. Equivalent to. Reference numeral 403 corresponds to a disk-type color filter for selecting and transmitting light having a wavelength corresponding to RGB.

  The laser light emitted from the panel 401 is white, but a color image can be displayed on the screen by rotating the color filter 403 in synchronization with a video signal for controlling the driving of the panel 401.

  Next, FIG. 4B shows another configuration of the projector of this embodiment. The projector shown in FIG. 4B is a three-plate type and has three panels corresponding to each color. Specifically, 421r corresponds to red (R), 421g corresponds to green (G), and 421b corresponds to blue (B). Reference numeral 422 corresponds to a projection optical system for controlling the optical path of the laser light emitted from the panels 421r to 421b and projecting it onto the screen.

  Further, the projector shown in FIG. 4B includes an optical system for synthesizing the laser beams of the respective colors emitted from the panels 421r to 421b. Specifically, FIG. 4B illustrates an example in which a dichroic prism 423 is used as an optical system for combining light. Since the laser beams of the respective colors emitted from the panels 421r to 421b are combined by the dichroic prism 423 and incident on the projection optical system 422, a color image can be displayed on the screen.

  Next, FIG. 4C illustrates another configuration of the projector of this embodiment. The projector shown in FIG. 4C is a three-plate type and has three panels corresponding to each color. Specifically, 411r corresponds to red (R), 411g corresponds to green (G), and 411b corresponds to blue (B). Reference numeral 412 corresponds to a projection optical system for controlling the optical path of laser light emitted from the panels 411r to 411b and projecting it onto the screen.

  Further, the projector shown in FIG. 4C uses dichroic mirrors 413g and 413b. The dichroic mirror 413g can reflect light in a wavelength region corresponding to green light and transmit other visible light. The dichroic mirror 413b can reflect light in a wavelength region corresponding to blue light and transmit other visible light. Therefore, the colors emitted from the panels 411r to 411b are combined and incident on the projection optical system 412, so that a color image can be displayed on the screen.

  In FIG. 4C, three colors of laser light are synthesized by reflecting green laser light and blue laser light with a dichroic mirror, but the colors of the laser light reflected by the dichroic mirror are the same. It is not limited, and the number of dichroic mirrors is not limited to this. What is necessary is just to synthesize | combine by reflecting at least 2 of a red, green, and blue laser beam with a dichroic mirror. Note that when a specific color laser beam is reflected by the dichroic mirror, the panel corresponding to the dichroic mirror may oscillate white laser beam.

  Since the projector shown in FIG. 4C does not need to use a dichroic prism, the cost can be reduced as compared with the case of FIG.

  Next, configurations of the front projector and the rear projector will be described. FIG. 10A shows an overall view of a front type projector, where 1001 is a projector and 1002 is a screen. An image can be displayed by projecting light emitted from the projector 1001 onto the screen 1002. In the case of a front type projector, a viewer can see an image projected on the screen 1002 from the side on which light is projected.

  FIG. 10B shows an overall view of the rear projector, where 1011 is a projector, 1012 is a screen, 1013 is a mirror, and 1014 is a cabinet. The light emitted from the projector 1011 has its optical path controlled by the mirror 1013 and is projected onto the screen 1002 so that an image can be displayed. In the case of a rear type projector, the viewer can see the image projected on the screen 1012 from the side opposite to the side on which the light is projected.

  Note that the present invention is not limited to the projector 1011, and a rear projector including a screen 1012, a mirror 1013, and the like may be included in its category.

  In the present embodiment, a mode different from that in FIG. 1 of the laser element having the first configuration will be described.

  One mode of the laser element of the present invention will be described with reference to FIG. FIG. 5A is a cross-sectional view of a laser element provided in a panel included in the projector according to the invention, and a substrate 501 having a recess 500 and a planarization layer formed on the substrate 501 so as to cover the recess 500. 502. As the substrate 501, glass, quartz, metal, bulk semiconductor, plastic, or the like can be used. The planarization layer 502 is formed with a thickness sufficient to fill the recess 500. The substrate 501 has a lower refractive index than the planarization layer 502, and the planarization layer 502 has a light-transmitting property.

  Note that FIG. 5A illustrates an example in which the planarization layer 502 is formed using one layer; however, the planarization layer 502 may be formed using a plurality of layers. However, in this case, the refractive index of the substrate 501 is set lower than the refractive index of the layer closest to the substrate 501 in the planarization layer 502.

  In FIG. 5A, the light-emitting element 503 is formed over the planarization layer 502 so as to overlap with the concave portion 500. The light-emitting element 503 includes two electrodes 504 and 505 and an electroluminescent layer 506 provided between the electrodes 504 and 505. Note that one of the electrodes 504 and 505 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 504 and 505, current is supplied to the electroluminescent layer 506, and the electroluminescent layer 506 can emit light.

  Note that the substrate 501 has a curved surface in the concave portion 500, and the center of curvature of the curved surface exists on the light emitting element 503 side.

  In the laser element illustrated in FIG. 5A, an optical resonator is formed by electrodes 504 and 505 included in the light-emitting element 503. Laser light is oscillated from the electrode 504 side by the light emitted from the electroluminescent layer 506 being resonated by the electrodes 504 and 505.

  The oscillated laser beam is diverged to some extent, but is reflected by the recess 500, so that the divergence angle is suppressed and the directivity is increased. In order to suppress the divergence angle, the focal length of the concave portion 500 may be optically designed in accordance with the divergence angle of the laser light applied to the concave portion 500.

  Note that although FIG. 5A illustrates a mode in which the oscillated laser light is reflected at the concave portion to increase the directivity of the laser light, the laser light directivity is increased by being refracted at the convex portion. Anyway. With reference to FIG. 5B, a mode of a laser element that can improve the directivity of laser light by being refracted at a convex portion will be described.

  FIG. 5B is a cross-sectional view of the laser element provided in the panel included in the projector of the invention, and covers the substrate 510, the light-emitting element 511 formed over the substrate 510, and the light-emitting element 511. And a layer (convex layer) 512 having a convex portion 513 formed. The convex layer 512 has a light-transmitting property and has a convex portion 513 so as to overlap the light emitting element 511.

  5B shows an example in which the substrate 510 and the convex layer 512 are each formed of one layer, but may be formed of a plurality of layers.

  Note that the convex portion 513 may be formed using a droplet discharge method as shown in FIG. 8 after the convex layer 512 is formed.

  The convex layer 512 has a curved surface at the convex portion 513, and the center of curvature of the curved surface exists on the light emitting element 511 side.

  The light-emitting element 511 includes two electrodes 514 and 515 and an electroluminescent layer 516 provided between the electrodes 514 and 515. Note that one of the electrodes 514 and 515 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 514 and 515, current is supplied to the electroluminescent layer 516, and the electroluminescent layer 516 can emit light.

  5B, an optical resonator is formed by electrodes 514 and 515 included in the light-emitting element 511 similarly to the laser element illustrated in FIG. 5A. Laser light is oscillated from the electrode 515 by the light emitted from the electroluminescent layer 516 being resonated by the electrodes 514 and 515.

  Although the oscillated laser beam diverges to some extent, it is refracted at the convex portion 513 so that the divergence angle is suppressed and the directivity is increased. In order to suppress the divergence angle, the focal length of the convex portion 513 may be optically designed in accordance with the divergence angle of the laser light applied to the convex portion 513.

  Further, the laser element of the present invention may be formed such that a concave part for reflecting laser light and a convex part for refracting face each other with the light emitting element interposed therebetween. The form of the laser element of the present invention in which the concave portion and the convex portion face each other will be described with reference to FIG.

  FIG. 5C is a cross-sectional view of the laser element provided in the panel included in the projector of the invention, and the substrate 521 having the recess 520 and the planarization formed over the substrate 521 so as to cover the recess 520. Layer 522. As the substrate 521, glass, quartz, metal, bulk semiconductor, plastic, or the like can be used. The planarization layer 522 is formed with a thickness enough to fill the recess 520. The substrate 521 has a lower refractive index than the planarization layer 522, and the planarization layer 522 has a light-transmitting property.

  Note that in FIG. 5C, the planarization layer 522 may be formed of one layer or a plurality of layers as in the case of FIG.

  In FIG. 5C, the light-emitting element 523 is formed over the planarization layer 522 so as to overlap with the concave portion 520, and the convex layer 524 having the convex portion 528 is formed so as to cover the light-emitting element 523. Yes. The light-emitting element 523 includes two electrodes 525 and 526 and an electroluminescent layer 527 provided between the electrodes 525 and 526. Note that one of the electrodes 525 and 526 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 525 and 526, current is supplied to the electroluminescent layer 527, and the electroluminescent layer 527 can emit light.

  The convex layer 524 has a light-transmitting property and has a convex portion 528 so as to overlap with the light-emitting element 523. Note that FIG. 5C illustrates an example in which the convex layer 524 is formed of one layer, but the convex layer 524 may be formed of a plurality of layers.

  Note that the convex portion 528 may be formed by a droplet discharge method.

  The substrate 521 has a curved surface in the recess 520, and the center of curvature of the curved surface exists on the light emitting element 523 side. The convex layer 524 has a curved surface at the convex portion 528, and the center of curvature of the curved surface exists on the light emitting element 523 side.

  In the laser element illustrated in FIG. 5C, an optical resonator is formed by electrodes 525 and 526 included in the light-emitting element 523. The light emitted from the electroluminescent layer 527 is resonated by the electrodes 525 and 526, so that laser light is oscillated from the electrode 525.

  The laser light oscillated from the electrode 525 diverges to some extent, but is reflected by the recess 520, so that the divergence angle is suppressed and the directivity is increased. In order to suppress the divergence angle, the focal length of the concave portion 520 may be optically designed in accordance with the divergence angle of the laser light applied to the concave portion 520. In the laser element illustrated in FIG. 5C, the light reflected by the concave portion 520 can be condensed by being refracted by the convex portion 528 of the convex layer 524.

  As described above, the laser element having the first configuration shown in this embodiment includes a recess provided in a layer for supporting the light emitting element (substrate in this embodiment) or a layer covering the light emitting element (this embodiment). Then, the directivity of the laser beam oscillated from the optical resonator can be increased by the convex portion of the convex layer. And since a part of layer functions as an optical system, unlike the case where an optical system is provided separately, the tolerance with respect to a physical impact can be improved.

  Note that although the laser elements illustrated in FIGS. 5A to 5C resonate light between two electrodes included in the light-emitting element, the present invention is not limited to this structure. Light may be caused to resonate with a reflection film formed separately, or generated in the light emitting layer in a layer other than the light emitting layer included in the electroluminescent layer, such as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, etc. The reflected light may be reflected to form an optical resonator.

  In this embodiment, a mode different from that shown in FIG. 2 of the laser element having the second configuration will be described.

  An embodiment of the laser element of the present invention will be described with reference to FIG. FIG. 6A is a cross-sectional view of a laser element provided in a panel included in the projector of this embodiment, and a substrate 601 having a recess 600 and planarization formed on the substrate 601 so as to cover the recess 600. Layer 602. As the substrate 601, glass, quartz, metal, bulk semiconductor, plastic, or the like can be used. The planarization layer 602 is formed with a thickness sufficient to fill the recess 600. The substrate 601 has a lower refractive index than the planarization layer 602, and the planarization layer 602 has a light-transmitting property.

  Note that FIG. 6A illustrates an example in which the planarization layer 602 is formed using one layer; however, the planarization layer 602 may be formed using a plurality of layers. However, in this case, the refractive index of the substrate 601 is set lower than the refractive index of the layer closest to the substrate 601 in the planarization layer 602.

  In FIG. 6A, the light-emitting element 603 is formed over the planarization layer 602 so as to overlap with the concave portion 600. The light-emitting element 603 includes two electrodes 604 and 605 and an electroluminescent layer 606 provided between the electrodes 604 and 605. Note that one of the electrodes 604 and 605 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 604 and 605, current is supplied to the electroluminescent layer 606, and the electroluminescent layer 606 can emit light.

  In the laser element illustrated in FIG. 6A, the electrode 605 included in the light-emitting element 603 and the substrate 601 function as a reflective material, and an optical resonator is formed by the two reflective materials. Note that the substrate 601 has a curved surface in the concave portion 600, and the center of curvature of the curved surface exists on the light emitting element 603 side. Since the electrode 605 functioning as a reflector has a flat surface, the laser element illustrated in FIG. 6A corresponds to a hemispherical system. Light emitted from the electroluminescent layer 606 located between the electrode 605 and the substrate 601 is resonated by the electrode 605 and the substrate 601 and is oscillated from the electrode 605 as laser light.

  The optical resonator formed by the electrode 605 and the substrate 601 is a stable resonator, and the distance L between the electrode 605 and the substrate 601 corresponding to the resonator length and the focal length f are f ≧ L / 2 is satisfied. With the above structure, the oscillation efficiency of laser light oscillated from the electrode 605 side can be increased.

  Note that in FIG. 6A, an electrode of a light-emitting element is used as a planar reflective material; however, the present invention is not limited to this structure. A film having a plane other than the electrodes may be used as the reflecting material. In FIG. 6A, the substrate 101 is used as a reflective material having a recess, but the present invention is not limited to this structure. A recess may be provided in an electrode included in the light-emitting element to resonate light between the two electrodes.

  The laser element of the present invention is not limited to a hemispherical system, and may be a confocal system, a concentric system, or a spherical system in which two reflecting materials have curved surfaces. The form of the laser element of the present invention corresponding to the confocal system will be described with reference to FIG.

  FIG. 6B is a cross-sectional view of the laser element provided in the panel included in the projector of this embodiment, and the substrate 621 having the recess 620 and the planarization formed on the substrate 621 so as to cover the recess 620. Layer 622. As the substrate 621, glass, quartz, metal, bulk semiconductor, plastic, or the like can be used. The planarization layer 622 is formed with a thickness enough to fill the recess 620. The substrate 621 has a lower refractive index than the planarization layer 622, and the planarization layer 622 has a light-transmitting property.

  Note that FIG. 6B illustrates an example in which the planarization layer 622 is formed using one layer; however, the planarization layer 622 may be formed using a plurality of layers. However, in this case, the refractive index of the substrate 621 is set lower than the refractive index of the layer closest to the substrate 621 in the planarization layer 622.

  In FIG. 6B, the light-emitting element 623 is formed over the planarization layer 622 so as to overlap with the concave portion 620. The light-emitting element 623 includes two electrodes 624 and 625 and an electroluminescent layer 626 provided between the electrodes 624 and 625. Note that one of the electrodes 624 and 625 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 624 and 625, a current is supplied to the electroluminescent layer 626 so that the electroluminescent layer 626 can emit light.

  In FIG. 6B, a convex layer 627 is formed so as to cover the light-emitting element 623. The convex layer 627 has a light-transmitting property and has a convex portion 628 so as to overlap with the light-emitting element 623. A reflective film 629 that functions as a reflective material is formed on the convex layer 627 so as to cover the convex part 628. The reflective film 629 is made of a material having a lower refractive index than that of the convex layer 627.

  The reflective film 629 can be formed by a vapor deposition method using a material containing one or more metal elements such as Al, Ag, Ti, W, Pt, and Cr. Note that the reflective film is not limited to the above materials, and may be any film that can reflect light. For example, a film in which insulating films having different refractive indexes such as silicon oxide, silicon nitride, and titanium oxide are alternately stacked may be used as the reflective film.

  Note that FIG. 6B illustrates an example in which each of the convex layer 627 and the reflective film 629 is formed of one layer, but may be formed of a plurality of layers. However, the refractive index of the layer closest to the reflective film 629 in the convex layer 627 is set higher than the refractive index of the layer closest to the convex layer 627 in the reflective film 629.

  In the laser element shown in FIG. 6B, the substrate 621 and the reflective film 629 function as a reflective material, and an optical resonator is formed by the two reflective materials. Note that the substrate 621 has a curved surface in the recess 620, and the center of curvature of the curved surface exists on the light emitting element 623 side. The reflective film 629 has a curved surface in a portion overlapping the convex portion 628 of the convex layer 627, and the center of curvature of the curved surface exists on the light emitting element 623 side. The laser element illustrated in FIG. 6B corresponds to a confocal system. Therefore, when the distance between the substrate 621 corresponding to the resonator length and the reflective film 629 is L, the radius of curvature of the substrate 621 is r1, and the radius of curvature of the reflective film 629 is r2, L = (r1 + r2) / 2 is satisfied. .

  Note that the diffraction loss can be minimized when the curvature radii r1 and r2 of the two reflectors and the resonator length L are completely equal. However, when there is a difference between the radii of curvature r1 and r2, and the resonator length L falls between the two radii of curvature r1 and r2, the diffraction loss becomes extremely large, so that an error in the radius of curvature expected in the manufacturing process of the recesses. A near-confocal system in which two reflectors are arranged with a distance larger than the range shifted from the confocal position may be used.

  The laser element of the present invention is not limited to the confocal system, and may be a concentric system or a spherical system. When forming a concentric system, L = r1 + r2 is satisfied. When forming a spherical system, r1 = r2 = L / 2 is satisfied.

  Then, light emitted from the electroluminescent layer 626 located between the substrate 621 and the reflective film 629 is resonated by the substrate 621 and the reflective film 629 and is oscillated from the reflective film 629 as laser light.

  Since the optical resonator shown in FIG. 6B is a stable resonator, the resonator length L, the radius of curvature r1, and the radius of curvature r2 satisfy the following equation (2).

  Incidentally, the focal length f corresponds to half of the radius of curvature r. With the above structure, the oscillation efficiency of the laser light oscillated from the electrode 625 side can be increased.

  In the laser element of the present invention, a convex portion that functions as an optical system for refracting laser light may be provided in a hemispherical optical resonator using a light emitting element. A mode of the laser element of the present invention having a convex portion functioning as an optical system will be described with reference to FIG.

  FIG. 6C is a cross-sectional view of the laser element provided in the panel included in the projector of this embodiment. The substrate 631 having the recess 630 and the planarization formed on the substrate 631 so as to cover the recess 630 are illustrated. Layer 632. As the substrate 631, glass, quartz, metal, bulk semiconductor, plastic, or the like can be used. The planarization layer 632 is formed with a thickness enough to fill the recess 630. The substrate 631 has a lower refractive index than the planarization layer 632, and the planarization layer 632 has a light-transmitting property.

  Note that FIG. 6C illustrates an example in which the planarization layer 632 is formed using one layer; however, the planarization layer 632 may be formed using a plurality of layers. However, in this case, the refractive index of the substrate 631 is set lower than the refractive index of the layer closest to the substrate 631 in the planarization layer 632.

  In FIG. 6C, the light-emitting element 633 is formed over the planarization layer 632 so as to overlap with the concave portion 630, and the convex layer 634 is formed so as to cover the light-emitting element 633. The light-emitting element 633 includes two electrodes 635 and 636 and an electroluminescent layer 637 provided between the electrodes 635 and 636. Note that one of the electrodes 635 and 636 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 635 and 636, current is supplied to the electroluminescent layer 637, and the electroluminescent layer 637 can emit light.

  The convex layer 634 has a light-transmitting property and has a convex portion 638 so as to overlap the light-emitting element 633.

  The substrate 631 has a curved surface in the recess 630, and the center of curvature of the curved surface exists on the light emitting element 633 side. The convex layer 634 has a curved surface at the convex portion 638, and the center of curvature of the curved surface exists on the light emitting element 633 side.

  FIG. 6C illustrates an example in which the convex portion layer 634 is formed of one layer, but it may be formed of a plurality of layers.

  In the laser element illustrated in FIG. 6C, the electrode 635 included in the light-emitting element 633 and the substrate 631 function as a reflective material, and an optical resonator is formed using the two reflective materials. Note that the substrate 631 has a curved surface in the recess 630, and the center of curvature of the curved surface exists on the light emitting element 633 side. Since the electrode 635 functioning as a reflector has a flat surface, the laser element illustrated in FIG. 6C corresponds to a hemispherical system. Light emitted from the electroluminescent layer 637 located between the electrode 635 and the substrate 631 is resonated by the electrode 635 and the substrate 631 and is oscillated from the electrode 635 as laser light.

  The optical resonator formed by the electrode 635 and the substrate 631 is a stable resonator, and the distance L between the electrode 635 and the substrate 631 corresponding to the resonator length and the focal length f are f ≧ L / 2 is satisfied. With the above structure, the oscillation efficiency of laser light oscillated from the electrode 635 side can be increased.

  Although the oscillated laser beam diverges to some extent, it is refracted by the convex portion 638, whereby the divergence angle is suppressed and the directivity is increased. In order to suppress the divergence angle, the focal length of the convex portion 638 may be optically designed in accordance with the divergence angle of the laser light applied to the convex portion 638. In the laser element illustrated in FIG. 6C, part of the layer functions as an optical system; therefore, unlike a case where a separate optical system is provided, resistance to physical impact can be increased.

  Note that the protrusion 638 may be formed using a droplet discharge method after the protrusion layer 634 is formed.

  Note that in FIG. 6C, a substrate is used as a reflective material having a recess, but the present invention is not limited to this structure. A concave portion may be provided in the electrode included in the light-emitting element and used as a reflective material. In FIG. 6C, the electrode of the light emitting element is used as the reflecting material having a flat surface, but the present invention is not limited to this structure. A film having a plane other than the electrodes may be used as the reflecting material.

  Note that the laser elements shown in FIGS. 6A to 6C resonate light by using two electrodes included in the light-emitting element and a separately provided reflector, but the present invention has this configuration. It is not limited to. Forms a curved surface in a layer other than the light emitting layer included in the electroluminescent layer, for example, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, etc., and reflects light generated in the light emitting layer to form an optical resonator You may do it.

  In this example, a mode different from that of FIG. 3 of the laser element having the third configuration will be described.

  One mode of the laser element of the present invention will be described with reference to FIG. FIG. 7A is a cross-sectional view of the laser element provided in the panel included in the projector of this embodiment, and is formed on the substrate 701 so as to overlap with the substrate 701 having the protrusion 700 and the protrusion 700. A light-emitting element 702. The convex portion 700 has a curved surface, and the center of curvature of the curved surface exists on the side opposite to the light emitting element 702.

  Note that FIG. 7A illustrates an example in which the light-emitting element 702 is formed directly over the substrate 701; however, the present invention is not limited to this structure. One or more other films such as an insulating film and a reflective film may be formed between the substrate 701 and the light emitting element 702. In FIG. 7A, the substrate 701 having the convex portion 700 is used, but the convex portion may be formed using a film different from the substrate over a flat substrate. For example, the convex portion 700 may be formed using a droplet discharge method.

  As the substrate 701, glass, quartz, metal, bulk semiconductor, plastic, or the like can be used.

  The light-emitting element 702 includes an electrode 703 formed over the substrate 701, an electroluminescent layer 704 formed over the electrode 703, and an electrode 705 formed over the electroluminescent layer 704 so as to overlap the electrode 703. . The electrode 703 formed on the substrate 701 has a curved surface on the surface by the convex portion 700 included in the substrate 701, and the center of curvature of the curved surface exists on the substrate 701 side.

  Note that one of the electrodes 703 and 705 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 703 and 705, current is supplied to the electroluminescent layer 704, so that the electroluminescent layer 704 can emit light.

  In the laser element illustrated in FIG. 7A, an optical resonator is formed by using the electrodes 703 and 705 included in the light-emitting element 702 as reflecting materials. The light emitted from the electroluminescent layer 704 is resonated by the electrodes 703 and 705 and is oscillated from the electrode 705 side as laser light.

  By applying a voltage between the electrodes 703 and 705, the light generated in the electroluminescent layer 704 is resonated. Assuming that the electrode 705 has a plane, this optical resonator is an unstable resonator. Therefore, the distance L between the electrodes 703 and 705 corresponding to the resonator length and the focal length f (f <0) of the curved surface of the electrode 703 satisfy f <L / 2. Note that since twice the focal length f corresponds to the radius of curvature r, it can be said that r <L. With the above structure, the oscillation efficiency of single-mode laser light can be increased.

  When the electrode 705 has a curved surface and the center of curvature of the curved surface exists on the electrode 703 side, in order to form an unstable resonator, the resonator length L and the radius of curvature r1 of the electrode 703 (r1 <0). ), The radius of curvature r2 (r2> 0) needs to satisfy at least one of the two formulas shown in Equation 1 above.

  Note that although FIG. 7A illustrates a mode in which a single-mode laser light oscillation efficiency is increased using a reflective material having a convex portion, a reflective material having a concave portion may be used. The form of the laser element of the present invention using a reflective material having a recess will be described with reference to FIG.

  FIG. 7B is a cross-sectional view of the laser element provided in the panel included in the projector of this embodiment. The substrate 711 having the recess 710 and the light-emitting element formed over the substrate 711 so as to overlap the recess 710. 712. As the substrate 711, glass, quartz, metal, bulk semiconductor, plastic, or the like can be used.

  Note that FIG. 7B illustrates an example in which the light-emitting element 712 is formed directly over the substrate 711; however, the present invention is not limited to this structure. One or a plurality of other films such as an insulating film and a film for reflecting light (reflection film) may be formed between the substrate 711 and the light emitting element 712. In FIG. 7B, the substrate 711 having the recess 710 is used; however, the recess may be formed using a film different from the substrate over a flat substrate.

  The concave portion 710 has a curved surface, and the center of curvature of the curved surface exists on the light emitting element 712 side.

  The light-emitting element 712 includes an electrode 713 formed over the substrate 711, an electroluminescent layer 714 formed over the electrode 713, and an electrode 715 formed over the electroluminescent layer 714 so as to overlap the electrode 713. . Note that one of the electrodes 713 and 715 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 713 and 715, current is supplied to the electroluminescent layer 714 and the electroluminescent layer 714 can emit light.

  In the laser element illustrated in FIG. 7B, an optical resonator is formed by electrodes 713 and 715 included in the light-emitting element 712, similarly to the laser element illustrated in FIG. Light emitted from the electroluminescent layer 714 is resonated by the electrodes 713 and 715 and oscillated from the electrode 715 side as laser light.

  The optical resonator formed by the electrodes 713 and 715 is an unstable resonator. In the case of FIG. 7B, in order to form an unstable resonator, the distance L between the electrodes 713 and 715 corresponding to the resonator length and the focal length f (f <0) of the curved surface of the electrode 713 are f. It is necessary to satisfy <L / 2.

  When the electrode 715 has a curved surface and the center of curvature of the curved surface exists on the electrode 713 side, in order to form an unstable resonator, the resonator length L and the radius of curvature r1 of the electrode 713 (r1 <0). ), The radius of curvature r2 (r2> 0) needs to satisfy at least one of the two formulas shown in Equation 1 above. With the above structure, single-mode laser light can be easily obtained from laser light oscillated from the electrode 715 side, and thus the oscillation efficiency of the single-mode laser light can be increased.

  In this example, one mode in which a film having a convex portion is formed over a light-emitting element in the laser element illustrated in FIG. 7C will be described.

  FIG. 7C is a cross-sectional view of the laser element provided in the panel included in the projector of this embodiment. The substrate 721 having the recess 720 and the light-emitting element formed over the substrate 721 so as to overlap the recess 720. 722. As the substrate 721, glass, quartz, metal, bulk semiconductor, plastic, or the like can be used.

  Note that FIG. 7C illustrates an example in which the light-emitting element 722 is directly formed over the substrate 721; however, the present invention is not limited to this structure. One or more other films such as an insulating film and a reflective film may be formed between the substrate 721 and the light emitting element 722. In FIG. 7C, the substrate 721 having the recess 720 is used, but the recess may be formed using a film different from the substrate over a flat substrate.

  The concave portion 720 has a curved surface, and the center of curvature of the curved surface exists on the light emitting element 722 side.

  The light-emitting element 722 includes an electrode 723 formed over the substrate 721, an electroluminescent layer 724 formed over the electrode 723, and an electrode 725 formed over the electroluminescent layer 724 so as to overlap the electrode 723. . Note that one of the electrodes 723 and 725 is an anode and the other is a cathode. By applying a forward bias voltage between the electrodes 723 and 725, current is supplied to the electroluminescent layer 724 and the electroluminescent layer 724 can emit light.

  In FIG. 7C, a convex film 727 having a convex part 726 is formed so as to cover the light-emitting element 722. The convex portion 726 is formed so as to overlap with the light emitting element 722. The convex film 727 may be formed of a single layer film or a plurality of films. In any case, the convex film 727 has translucency.

  In the laser element illustrated in FIG. 7C, an optical resonator is formed by electrodes 723 and 725 included in the light-emitting element 722, similarly to the laser element illustrated in FIG. 7B. The light emitted from the electroluminescent layer 724 is resonated by the electrodes 723 and 725 and oscillated from the electrode 725 side as laser light.

  Note that the optical resonator formed by the electrodes 723 and 725 is an unstable resonator. Therefore, it is considered that the oscillated laser light is easier to obtain single-mode laser light than the stable resonator, and the directivity is enhanced. In this embodiment, the laser light is refracted at the convex portion 726 included in the convex layer 727, so that the divergence angle can be suppressed and the directivity of the laser light can be further increased. In order to suppress the divergence angle, the focal length of the convex portion 726 may be optically designed in accordance with the divergence angle of the laser light applied to the convex portion 726.

  Note that in FIG. 7C, two electrodes included in the light-emitting element are used as a reflective material; however, the present invention is not limited to this structure. In addition to the light emitting element, two additional reflective materials may be provided, or one of the electrodes of the light emitting device may be used as a reflective material, and one additional reflective material may be provided.

  In FIGS. 7A to 7C, two electrodes included in the light-emitting element are used as a reflective material; however, the present invention is not limited to this structure. In addition to the light emitting element, two additional reflecting materials may be provided, or one of the electrodes of the light emitting element may be used as the reflecting material, and one additional reflecting material may be provided. Alternatively, a layer other than the light-emitting layer included in the electroluminescent layer, for example, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, or the like is used as a reflective material, and light generated in the light-emitting layer is reflected, so May be formed.

  In this example, an example of a method for manufacturing a planarization layer will be described.

  First, as shown in FIG. 9A, a reflective film 802 is formed over a substrate 801 having a recess 800. The reflective film 802 can be formed of a material that can reflect light. For example, a material including one or more metal elements such as Al, Ag, Ti, W, Pt, and Cr is used, and an evaporation method is used. Can be formed. Note that the reflective film is not limited to the above materials, and may be any film that can reflect light. For example, a film in which insulating films having different refractive indexes such as silicon oxide, silicon nitride, and titanium oxide are alternately stacked may be used as the reflective film.

  Next, as illustrated in FIG. 9B, a planarization layer 803 is formed over the substrate 801 so as to fill the recess 800. The planarization layer 803 is formed using a light-transmitting material and capable of CMP polishing. For example, an inorganic insulating film such as silicon oxide or silicon nitride oxide, or an insulating film including a Si—O bond and a Si—CHx crystal formed using a siloxane-based material as a starting material can be used. In this embodiment, an insulating film including a Si—O bond and a Si—CH x crystal formed using a siloxane-based material as a starting material is used as the planarization layer 803.

  Next, as illustrated in FIG. 9C, the surface of the planarization layer 803 is polished by a CMP method so that unevenness on the surface of the planarization layer 803 caused by the recesses 800 is planarized. The CMP method can be performed by a known method. For example, a solid-liquid dispersion slurry in which an abrasive having a diameter of 100 to 1000 nm such as fumed silica, alkali silica, or cerium oxide is dispersed in an aqueous solution containing a reagent such as a pH adjuster can be used. In this embodiment, silica slurry (pH = 10 to 11) in which fumed silica particles obtained by thermally decomposing silicon chloride gas in an aqueous solution to which potassium hydroxide is added is dispersed at 20 wt% is used.

  By polishing using the CMP method, the surface of the planarization layer 803 is planarized as illustrated in FIG.

  Then, a light-emitting element 804 is formed over the planarized planarization layer 803 so as to overlap with the concave portion 800. The light-emitting element 804 includes two electrodes 805 and 806 and an electroluminescent layer 807 provided between the electrodes 805 and 806. Note that one of the electrodes 805 and 806 is an anode and the other is a cathode.

  In the laser element illustrated in FIG. 9D, an optical resonator may be formed using the electrodes 805 and 806 included in the light-emitting element 804, or an optical resonator may be formed using the reflective film 802 and the electrode 806. good.

  In this embodiment, a structure of a light emitting element used in the projector of the present invention will be described.

  FIG. 11 shows one mode of an element structure of a light-emitting element used in the present invention. The light-emitting element shown in FIG. 11 has a structure in which an electroluminescent layer 1108 is sandwiched between an anode 1101 and a cathode 1107. The electroluminescent layer 1108 includes a hole injection layer 1102, a hole transport layer 1103, a light emitting layer 1104, an electron transport layer 1105, and an electron injection layer 1106, which are sequentially stacked from the anode 1101 side.

  Note that a light-emitting element used for a laser element only needs to include at least a light-emitting layer in an electroluminescent layer. Layers having functions other than light emission (a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer) can be appropriately combined. Specific examples of materials that can be used for each of the above layers are given below. However, materials applicable to the present invention are not limited to these.

  As the anode 1101, a conductive material having a high work function is preferably used. In the case where light is transmitted through the anode 1101, a highly light-transmitting material is used. In this case, a transparent conductive material such as indium-tin oxide (ITO), indium-zinc oxide (IZO), or indium-tin oxide containing silicon oxide (ITSO) may be used. In the case where the anode 1101 is used as a reflective material, a material that can reflect light is used. In this case, for example, in addition to a single layer film made of one or more of TiN, ZrN, Ti, W, Ni, Pt, Cr, Ag, etc., a laminate of titanium nitride and a film mainly composed of aluminum, a titanium nitride film For example, a three-layer structure of a film mainly containing aluminum and a titanium nitride film can be used. Alternatively, the above-described transparent conductive material may be stacked over the material that can reflect light and used as the anode 1101.

As a hole injection material that can be used for the hole injection layer 1102, a material having a relatively small ionization potential and a small absorption in the visible light region is preferable. Broadly divided into metal oxides, low-molecular organic compounds, and high-molecular organic compounds. As the metal oxide, for example, vanadium oxide, molybdenum oxide, ruthenium oxide, aluminum oxide, or the like can be used. If low molecular weight organic compound, for example, starburst amine typified by m-MTDATA, copper phthalocyanine (abbreviation: Cu-Pc) in the metal phthalocyanine represented, phthalocyanine (abbreviation: H ₂ -Pc), _2, A 3-dioxyethylenethiophene derivative or the like can be used. A film in which a low molecular organic compound and the metal oxide are co-evaporated may be used. As a high molecular organic compound, for example, a polymer such as polyaniline (abbreviation: PAni), polyvinyl carbazole (abbreviation: PVK), or a polythiophene derivative can be used. Polyethylene dioxythiophene (abbreviation: PEDOT), which is one of polythiophene derivatives, doped with polystyrene sulfonic acid (abbreviation: PSS) may be used.

As a hole transport material that can be used for the hole transport layer 1103, a known material that has high hole transportability and low crystallinity can be used. Aromatic amine-based compounds (that is, those having a benzene ring-nitrogen bond) are preferred, for example, 4,4-bis [N- (3-methylphenyl) -N-phenylamino] biphenyl (TPD) And 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl (α-NPD) which is a derivative thereof. Starburst type aromatic amine compounds such as 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine (TDATA) and MTDATA can also be used. Alternatively, 4,4 ′, 4 ″ -tris (N-carbazolyl) triphenylamine (abbreviation: TCTA) may be used. As the polymer material, poly (vinyl carbazole) or the like showing good hole transportability can be used. Further, an inorganic material such as MoO ₃ may be used.

A known material can be used for the light emitting layer 1104. For example, tris (8-quinolinolato) aluminum (Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (Almq ₃ ), bis (10-hydroxybenzo [η] -quinolinato) beryllium (BeBq ₂ ), bis ( 2-methyl-8-quinolinolato)-(4-hydroxy-biphenylyl) -aluminum (BAlq), bis [2- (2-hydroxyphenyl) -benzoxazolate] zinc (Zn (BOX) ₂ ), bis [2 A metal complex such as-(2-hydroxyphenyl) -benzothiazolate] zinc (Zn (BTZ) ₂ ) can be used. Various fluorescent dyes (coumarin derivatives, quinacridone derivatives, rubrene, 4,4-dicyanomethylene, 1-pyrone derivatives, stilbene derivatives, various condensed aromatic compounds, etc.) can also be used. Phosphorescent materials such as platinum octaethylporphyrin complex, tris (phenylpyridine) iridium complex, tris (benzylideneacetonato) phenanthrene europium complex can also be used. In particular, phosphorescent materials have a longer excitation lifetime than fluorescent materials, so it is easy to create an inversion distribution that is essential for laser oscillation, that is, a state in which the number of molecules in the excited state is larger than the number of molecules in the ground state. Become. The above materials can be used both as a dopant and as a single layer film.

  As a host material used for the light-emitting layer 1104, a hole transport material or an electron transport material typified by the above example can be used. Alternatively, a bipolar material such as 4,4′-N, N′-dicarbazolylbiphenyl (abbreviation: CBP) can be used.

As an electron transport material that can be used for the electron transport layer 1105, a metal complex having a quinoline skeleton or a benzoquinoline skeleton, a mixed ligand complex thereof, or the like, as typified by Alq ₃ , can be used. Specifically, metal complexes such as Alq ₃ , Almq ₃ , BeBq ₂ , BAlq, Zn (BOX) ₂ , and Zn (BTZ) ₂ can be given. In addition to metal complexes, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (PBD), 1,3-bis [5- (p Oxadiazole derivatives such as -tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (OXD-7), 3- (4-tert-butylphenyl) -4-phenyl-5 -(4-biphenylyl) -1,2,4-triazole (TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenylyl) -1,2, Triazole derivatives such as 4-triazole (p-EtTAZ); imidazole derivatives such as TPBI; It can be used derivatives.

As the electron injecting material that can be used for the electron injecting layer, the above-described electron transporting material can be used. In addition, an ultra-thin film of an insulator such as an alkali metal halide such as LiF or CsF, an alkaline earth halide such as CaF ₂ , or an alkali metal oxide such as Li ₂ O is often used. In addition, alkali metal complexes such as lithium acetylacetonate (abbreviation: Li (acac) and 8-quinolinolato-lithium (abbreviation: Liq) are also effective.

The cathode 1107 can be formed using a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like that has a low work function as used in a normal light-emitting element. Specifically, in addition to alkali metals such as Li and Cs, alkaline earth metals such as Mg, Ca and Sr, and alloys containing these (Mg: Ag, Al: Li, etc.), rare earths such as Yb and Er It can also be formed using a metal. Further, LiF, CsF, in the case of using an electron injecting layer such as CaF _2, Li ₂ O, may be used usual conductive thin film such as aluminum. When light is transmitted through the cathode 1107, an ultrathin film containing an alkali metal such as Li or Cs and an alkaline earth metal such as Mg, Ca, or Sr, a transparent conductive film (ITO, IZO, ZnO, or the like) The stacked structure may be used. Alternatively, an electron injection layer in which an alkali metal or an alkaline earth metal and an electron transport material are co-evaporated may be formed, and a transparent conductive film (ITO, IZO, ZnO, or the like) may be stacked thereon.

  The optical resonator allows laser light to oscillate from the reflective material having the higher transmittance by setting one of the two reflecting materials to have as high a reflectance as possible and the other having a certain degree of transmittance. Can do. For example, when the anode 1101 and the cathode 1107 are used as the reflection material on the laser light oscillation side, the material or film thickness is selected so that the transmittance is about 5 to 70%. In the case where a reflective material is separately formed, a material that transmits light in the anode 1101 or the cathode 1107 is selected.

  The interval between the reflectors (resonator length) is set to an integral multiple of half the wavelength λ to be resonated. And the laminated structure of a light emitting element is designed so that the light reflected in a reflecting material and the phase of the newly emitted light may correspond.

  Note that in manufacturing the light-emitting element described above, a stacking method of each layer in the light-emitting element is not limited. As long as lamination is possible, any method such as a vacuum deposition method, a spin coating method, an ink jet method, or a dip coating method may be selected.

  In this embodiment, a structure of a light emitting element used in the projector of the present invention will be described.

  FIG. 12 illustrates one embodiment of an element structure of a light-emitting element used in the present invention. The light-emitting element shown in FIG. 12 has a structure in which two electroluminescent layers 1303 and 1304 are sandwiched between an anode 1301 and a cathode 1302. Further, the light-emitting element illustrated in FIG. 12 includes a charge generation layer 1305 which is a floating electrode which is not connected to an external circuit between two electroluminescent layers 1303 and 1304. The electroluminescent layer 1303 includes a hole injection layer 1306, a hole transport layer 1307, a light emitting layer 1308, an electron transport layer 1309, and an electron injection layer 1310, which are sequentially stacked from the anode 1301 side. The electroluminescent layer 1304 includes a hole injection layer 1315, a hole transport layer 1311, a light emitting layer 1312, an electron transport layer 1313, and an electron injection layer 1314 which are sequentially stacked from the charge generation layer 1305 side.

  Note that a light-emitting element used for a laser element only needs to include at least a light-emitting layer in each electroluminescent layer. Layers having functions other than light emission (a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer) can be appropriately combined. The materials described in Example 6 can be referred to for the materials that can be used for the respective layers. However, the material applicable to the present invention is not limited to the material described in Example 6.

  When a forward bias voltage is applied between the anode 1301 and the cathode 1302 of the light-emitting element shown in FIG. 12, electrons are injected into the electroluminescent layer 1303 and holes are injected into the electroluminescent layer 1304, respectively. At 1304, carrier recombination occurs and light emission is obtained. With the above structure, when the distance between the anode 1301 and the cathode 1302 is constant, the energy of light emission obtained for the same current value is higher than when the electroluminescent layer is one. Therefore, the laser beam oscillation efficiency can be increased.

The electroluminescent layer 1305 is formed using a material that can transmit light. For example, ITO, a mixture of V ₂ O ₅ and an arylamine derivative, a mixture of MoO ₃ and an arylamine derivative, a mixture of V ₂ O ₅ and F4TCNQ (tetrafluorotetrathiafulvalene), or the like can be used.

  In the case where the anode 1301 and the cathode 1302 are used as reflecting materials, the material or the film thickness is selected so that the reflectance of one is as large as possible and the transmittance of the other is about 5 to 70%. In the case where a reflective material is separately formed, a material that transmits light in the anode 1301 or the cathode 1302 is selected. The interval between the reflectors is set to an integral multiple of half the wavelength λ to be resonated. And the laminated structure of a light emitting element is designed so that the light reflected in a reflecting material and the phase of the newly emitted light may correspond.

The figure which shows the structure of the projector of this invention, the top view and sectional drawing of a panel. The top view and sectional drawing of a panel. The top view and sectional drawing of a panel. FIG. 3 is a diagram illustrating a configuration of a projector according to the invention. Sectional drawing of a laser element. Sectional drawing of a laser element. Sectional drawing of a laser element. The figure which shows one Example of the production method of a convex part. 10A and 10B illustrate an example of a method for manufacturing a planarization layer. The figure which shows the structure of a front type and a rear type projector. FIG. 6 illustrates a structure of a light-emitting element. FIG. 6 illustrates a structure of a light-emitting element.

Claims (5)

A first electrode having a plurality of recesses;
An electroluminescent layer formed on and in contact with the first electrode so as to cover the plurality of recesses;
A second electrode formed on the electroluminescent layer so as to overlap the plurality of recesses;
A convex layer having a plurality of convex portions formed on the second electrode;
A reflective film formed to cover the convex layer having the plurality of convex parts;
An optical system,
The first electrode has a curved surface in the plurality of recesses,
The reflective film has a curved surface at the plurality of convex portions,
The convex layer having the plurality of convex portions has a refractive index lower than that of the reflective film,
The light generated in the electroluminescent layer is resonated between the first electrode and the reflective film, so that laser light is oscillated from the reflective film ,
The laser beam is projected onto a screen by the optical system. A first electrode having a plurality of convex portions;
An electroluminescent layer formed on and in contact with the first electrode so as to overlap the plurality of convex portions;
A second electrode formed on the electroluminescent layer so as to overlap the plurality of convex portions;
An optical system,
The first electrode has a curved surface at the plurality of convex portions,
Laser light is oscillated from the second electrode by the light generated in the electroluminescent layer being resonated between the first electrode and the second electrode,
The laser beam is projected onto a screen by the optical system. A first electrode having a plurality of recesses;
An electroluminescent layer formed on and in contact with the first electrode so as to overlap the plurality of recesses;
A second electrode formed on the electroluminescent layer so as to overlap the plurality of recesses;
An optical system,
The first electrode has a curved surface in the plurality of recesses,
The light generated in the electroluminescent layer is resonated between the first electrode and the second electrode, so that laser light is oscillated from the second electrode,
The radius of curvature of the curved surface is shorter than the distance between the first electrode and the second electrode on the extension line of the optical path of the laser beam,
The laser beam is projected onto a screen by the optical system. A reflector having a plurality of convex portions;
A first electrode that is formed on the reflector so as to overlap the plurality of convex portions and has translucency;
An electroluminescent layer formed on and in contact with the first electrode so as to overlap the plurality of convex portions;
A second electrode formed on the electroluminescent layer so as to overlap the plurality of protrusions;
An optical system,
The reflector has a curved surface at the plurality of convex portions,
The light generated in the electroluminescent layer is resonated between the reflector and the second electrode, so that laser light is oscillated from the second electrode,
The laser beam is projected onto a screen by the optical system. A reflector having a plurality of recesses;
A first electrode that is formed on the reflector so as to overlap the plurality of recesses and has translucency;
An electroluminescent layer formed on and in contact with the first electrode so as to overlap the plurality of recesses;
A second electrode formed on the electroluminescent layer so as to overlap the plurality of recesses;
An optical system,
The reflector has a curved surface in the plurality of recesses,
Laser light is oscillated from the second electrode by the light generated in the electroluminescent layer being resonated between the reflector and the second electrode,
The radius of curvature of the curved surface is shorter than the distance between the reflective material and the second electrode on the extended line of the optical path of the laser beam,
The laser beam is projected onto a screen by the optical system.

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