JP2005116799A - Luminous body and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminous body that can reduce the unevenness of a luminous pattern and, at the same time, can be increased in quantity of light without increasing etendue, and to provide a projector using the luminous body. <P>SOLUTION: Luminous bodies 12r, 12g, and 12b are respectively constituted by laminating luminous body chips 11r, 11g, and 11b having luminous areas 16a and nonluminous areas 16b upon another. The luminous body chips 11r, 11g, and 11b are laminated upon another so that the luminous areas 16a of the other luminous bodies chips 11r, 11g, and 11b may be disposed in the light emitting direction of the nonluminous area 16b of one luminous body chip 11r, 11g, and 11b. Of the plurality of laminated luminous body chips 11r, 11g, and 11b, the nonluminous areas 16b of the other luminous body chips 11r, 11g, and 11b laminated in the light emitting direction of at least one luminous body chip 11r, 11g, and 11b transmit light. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitter and a projector.

  In conventional projectors (projection display devices), a halogen lamp has been used as a light source in the past, and a high-pressure mercury lamp (UHP) having high luminance and high efficiency has been used in recent years. A light source using UHP, which is a discharge lamp, requires a high-voltage power circuit, is large and heavy, and hinders the reduction in size and weight of the projector. Further, although it has a longer life than a halogen lamp, it still has a short life, and it is almost impossible to control the light source (fast lighting, extinguishing, modulation), and it takes a long time to start up.

Therefore, recently, an LED illuminant has attracted attention as a new light source. LEDs are ultra-compact, ultra-light, and have a long life. In addition, by controlling the drive current, it is possible to freely turn on / off and adjust the amount of emitted light. In this respect, it is also promising as a light source for projectors, and application development has already started for small and portable small screen projectors.
Among them, in order to improve the light extraction efficiency, an LED light emitter has been proposed in which both the p-type and n-type electrodes are extracted from one surface and light is extracted from the entire surface of the other surface (for example, non-patent document). 1).
“High-intensity, high-efficiency, and long-life technology of white LED lighting system” Technical Information Association, Inc., March 27, 2003, p. 14

In the conventional LED light emitter described in Non-Patent Document 1, electrodes are formed in stripes on the surface of a p-type semiconductor layer, and the p-type semiconductor layer and the light-emitting layer are etched to stripe the n-type semiconductor layer. The electrode is formed on the surface.
In such a structure, since the light emitting portion has a stripe shape, there is a problem in that light emission from the LED light emitter is not uniform and a light emission pattern in a stripe shape.
Furthermore, since there is a region that does not emit light, there is a problem that the amount of light viewed from the area of the LED light emitter is reduced.

  Further, when this light source is used in a projector, the light emission pattern is stored up to the screen via the optical system, which causes image unevenness. The image unevenness described here is two, one is the unevenness of the image brightness, and the other is when the colored light R, G, B is superimposed, the light emission pattern of each color light is shifted. Color unevenness. This color irregularity is a conspicuous and big problem.

  The present invention has been made to solve the above-described problems, and provides a light emitter capable of reducing unevenness of a light emission pattern and increasing the amount of light without increasing etendue, and a projector using the light emitter. The purpose is to do.

  In order to achieve the above object, a light emitter of the present invention is a light emitter in which a light emitter chip having a light emitting region and a non-light emitting region for emitting light is laminated, and the light emitter of the non-light emitting region of one light emitter chip. The light emitting chips are stacked so that the light emitting areas of the other light emitting chips are arranged in the light emitting direction, and are stacked in the light emitting direction of at least one of the stacked light emitting chips. The non-light emitting area of another light emitting chip is characterized by transmitting light.

That is, the light emitter of the present invention has a light emitting region of another light emitter chip arranged in the light emitting direction of the non-light emitting region of one light emitter chip. The non-light emitting area can be eliminated. Further, the light emitted from the light emitting region of the lower light emitting chip with respect to the light emitting direction passes through the non-light emitting region of the upper light emitting chip and is emitted in the light emitting direction. Therefore, unevenness of the light emission pattern of the light emitter can be reduced, and unevenness of the illuminance distribution of the emitted light can be reduced.
Further, since the non-light emitting region is eliminated, the amount of emitted light can be increased without increasing the area of the light emitter (without increasing the etendue).

In order to realize the above configuration, more specifically, in the light emitting region and the non-light emitting region, an electrode for injecting charges into the light emitting chip is disposed, and at least the electrode disposed in the non-light emitting region is It is desirable to be formed from a material that transmits light emitted from the light emitting region.
According to this configuration, since the electrodes are arranged in the light emitting region and the non-light emitting region, it is possible to inject charges from the respective electrodes and to emit light from the light emitting layer.
In addition, since the electrode disposed at least in the non-light-emitting region is formed of a material that transmits light emitted from the light-emitting region, that is, a transparent material, the upper side without blocking light emitted from the lower-layer light emitting chip. Can be emitted.

More specifically, in order to realize the above configuration, the electrode includes one electrode and the other electrode, and the one electrode and the other electrode are disposed in the light emitting region and the non-light emitting region, respectively, It is desirable that the electrode and the other electrode are electrically connected to the mounting target in a region near one side of the light emitting chip.
According to this configuration, the one electrode and the other electrode are electrically connected to the mounting target in a region near one side of the light emitting chip. Therefore, even when the light emitting chips are stacked, by extending one side of the light emitting chips, it is possible to inject charges from the mounted object into the light emitting chips to emit light. In addition, the overlapping region of the light emitting chips can be gathered in the substantially central portion of the light emitting body, and the region in which the unevenness of the light emitting pattern is reduced can be arranged in the substantially central portion.

In order to realize the above configuration, more specifically, it is desirable that an adhesive having substantially the same refractive index as that of the light emitting chip is filled between the stacked light emitting chips.
According to this configuration, it is possible to prevent light emitted from the lower light emitting chip from being reflected at the boundary with the upper light emitting chip and being confined in the light emitting body. That is, the light emitted from the lower light emitting chip can enter the upper light emitting chip without being totally reflected, and can be emitted from the light emitting body. Therefore, it is possible to prevent light extraction loss due to light confinement in the luminous body.

In order to realize the above-described configuration, more specifically, it is desirable that the light emitting regions and the non-light emitting regions are formed in stripes alternately arranged, and the stripe widths of the light emitting regions and the non-light emitting regions are substantially the same. .
According to this configuration, since the stripe widths of the light emitting region and the non-light emitting region are formed substantially the same, the widths of the electrodes arranged in both regions can be made substantially the same. Therefore, the density of charges injected from both electrodes into the light emitting region and the non-light emitting region can be made uniform, and charges can be supplied to the light emitting region without excess or deficiency to emit light without waste.

  A projector according to the present invention is a projector including a light source, a light modulation unit that modulates light from the light source, and a projection unit that projects light modulated by the light modulation unit. It is characterized by having a body.

  That is, since the projector according to the present invention uses the light source including the light emitter according to the present invention, it is possible to reduce unevenness in brightness and color in the projected image.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a schematic configuration diagram of a projector according to the present embodiment.
As shown in FIG. 1, the projector 1 according to the present embodiment is a three-plate liquid crystal projector, and is a light source device (light source) capable of emitting R (red), G (green), and B (blue) color light respectively. 10R, 10G, and 10B, a rod lens 30 that equalizes the illuminance distribution of each color light, and a transmissive liquid crystal light valve (light modulation device) 40R, 40G, and 40B that modulates each color light whose illuminance distribution is uniformed, The cross dichroic prism 50 that synthesizes the modulated color light to form a color image, and a projection lens (projection means) 60 that projects the color image are roughly configured.

FIG. 2 is a schematic plan view of the light source device according to the present embodiment. FIG. 3 is a cross-sectional view taken along line AA in FIG.
The light source devices 10R, 10G, and 10B have the same structure and light emitters (LED stacked bodies 12r, 12g, and 12b) in which light emitter chips (LED chips 11r, 11g, and 11b) that emit RGB light are stacked. Since only the difference is made, the configuration of the light source device 10B will be described, and the description of the light source devices 10R and 10G will be omitted.
As shown in FIGS. 2 and 3, the light source device 10 </ b> B includes an LED laminate (light emitter) 12 b in which LED chips (light emitter chips) 11 b that emit B color light are laminated, and an LED laminate 12 b. The substrate 13 is configured to release heat generated from the LED laminate 12b to the outside.

The LED chip 11r is formed, for example, by laminating a transparent substrate 14 such as sapphire, a p-type semiconductor layer 15p such as p-GaN, and an n-type semiconductor layer 15n such as n-GaN in this order. The transparent substrate 14 is formed in a substantially square shape, and the n-type semiconductor layer 15n is formed in substantially the same shape as the transparent substrate 14. The p-type semiconductor layer 15p is formed in a substantially rectangular shape and arranged in a stripe shape, and the width of the region where the p-type semiconductor layer 15p is disposed and the region where the p-type semiconductor layer 15p is not disposed are substantially the same. Has been placed. In addition, the width | variety of the area | region where the p-type semiconductor layer 15p is arrange | positioned, and the area | region which is not arrange | positioned may be substantially the same as mentioned above, and may differ. Further, the transparent substrate 14 is more suitable for use in the light source device 10 </ b> B of the projector 1 because the thinner the transparent substrate 14, the better the heat dissipation and light extraction properties.
Since a light emitting layer (not shown) that emits light is formed between the p-type semiconductor layer 15p and the n-type semiconductor layer 15n, the region where the p-type semiconductor layer 15p is disposed has a light emitting region. On the contrary, a non-light emitting region 16b is formed in a region where the p-type semiconductor layer 15p is not disposed.

  An anode electrode (electrode) 17p for injecting charges into the p-type semiconductor layer 15p is disposed on the surface of the p-type semiconductor layer 15p, and a surface from which the n-type semiconductor layer 15n is exposed (the p-type semiconductor layer 15p is disposed). A cathode electrode (electrode) 17n for injecting charges into the n-type semiconductor layer 15n is disposed in the non-region). The anode electrode 17p is formed in substantially the same shape as the p-type semiconductor layer 15p, and the cathode electrode 17n is formed in a shape narrower than the exposed surface of the n-type semiconductor layer 15n so as not to contact the p-type semiconductor layer 15p on both sides. Has been. The anode electrode 17p is formed of a conductive material that does not transmit light, such as Au, Ag, or Cu, and the cathode electrode 17n is formed of a conductive material that transmits light, such as ITO (Indium Tin Oxide), for example. The anode 17p may be formed of a conductive material that does not transmit light as described above, but may be formed of a conductive material that transmits light, such as ITO.

  The LED laminate 18 is formed by superimposing two LED chips 11 b and bonding them together with an adhesive 20 having heat resistance and a refractive index substantially the same as that of the transparent substrate 14. The LED chip 11b of the LED stack 18 is overlaid so that the upper LED chip 11b light emitting region 16a is disposed on the non-light emitting region 16b of the lower LED chip 11b. At the same time, the upper and lower LED chips 11b are electrically connected to an anode mount portion 21p and a cathode mount portion 21n of the substrate 13, which will be described later. An area is formed.

  The substrate 13 is provided with an anode mount portion 21p for supplying charges to the anode electrode 17p and a cathode mount portion 21n for supplying charges to the cathode electrode 17n. The cathode mount portion 21n is formed in a U shape, and the anode mount portion 21p is disposed in the U shape. Contact members (contact portions) 22 made of solder balls that are electrically connected to the anode electrode 17p and the cathode electrode 17n are disposed on the anode mount portion 21p and the cathode mount portion 21n, respectively.

The rod lens 30 is formed in a prismatic shape using a transparent material such as glass, quartz, or transparent resin. The side surface of the rod lens 30 may be formed by depositing Ag or the like to form a reflective film, or the reflective film may not be formed.
The liquid crystal light valves 40R, 40G, and 40B use TN (Twisted Nematic) mode active matrix type transmissive liquid crystal cells that use thin film transistors (hereinafter abbreviated as TFTs) as pixel switching elements. Has been.
As shown in FIG. 1, the cross dichroic prism 50 has a structure in which four right-angle prisms are bonded together. A light reflecting film (not shown) made of a dielectric multilayer film is formed on the bonded surfaces 51a and 51b. It is formed in a shape. Specifically, light reflection that reflects red image light formed by the liquid crystal light valve 40R and transmits green and blue image light formed by the liquid crystal light valves 40G and 40B, respectively, to the bonding surface 51a. A film is provided on the bonding surface 51b, which reflects the blue image light formed by the liquid crystal light valve 40B and transmits the red and green image light formed by the liquid crystal light valves 40R and 40G, respectively. A membrane is provided.

Next, the operation of the projector 1 having the above configuration will be described.
First, the operation of the light source devices 10R, 10G, and 10B, which is a feature of the present invention, will be described.
Since the illumination devices 10R, 10G, and 10B have the same operation, the operation of the illumination device 10B will be described, and the description of the illumination devices 10R and 10G will be omitted.
As shown in FIGS. 2 and 3, in the lighting device 10B, when current is supplied, electric charges are supplied to the anode mount portion 21p and the cathode mount portion 21n of the substrate 13. The charges supplied to the anode mount portion 21p and the cathode mount portion 21n are injected via the contact member 22 into the anode electrode 17p and the cathode electrode 17n of the lower LED chip 11b and the upper LED chip 11b. The charges injected into the electrodes 17p and 17n are respectively injected into the p-type semiconductor layer 15p and the n-type semiconductor layer 15n, converted into colored light B in the light emitting layer (not shown), and emitted. The colored light B emitted toward the p-type semiconductor layer 15p is reflected by the anode electrode 17p, propagates in the order of the p-type semiconductor layer 15p, the n-type semiconductor layer 15n, and the transparent substrate 14, and is emitted from the LED chip 11b. The colored light B emitted toward the n-type semiconductor layer 15n propagates in the order of the n-type semiconductor layer 15n and the transparent substrate 14 and is emitted from the LED chip 11b. The colored light B is emitted out of the LED chip 11b from the light emitting region 16a where a light emitting layer (not shown) is formed.
The colored light B emitted from the LED chip 11b disposed in the lower layer of the LED stacked body 18 enters the non-light emitting region 16b of the LED chip 11b disposed in the upper layer. The colored light B passes through the cathode electrode 17n, the n-type semiconductor layer 15n, and the transparent substrate 14, and is emitted from the non-light emitting region 16b of the upper LED chip 11b.

As described above, the color light B emitted from the LED laminate 18 is incident on the rod lens 30. The colored light B that has entered the rod lens 30 propagates while being reflected in the rod lens 30, and the illuminance distribution is made uniform and emitted from the rod lens 30.
The color light B emitted from the rod lens 30 enters the liquid crystal light valve 40B, and is modulated and emitted based on the image signal input to the projector 1.
The modulated color light B is incident on the cross dichroic prism 50 and, like the color light B, is emitted from the light source devices 10R and 10G and synthesized with the color lights R and G modulated by the liquid crystal light valves 40R and 40G to form a color image. Projection lens 60 projects onto screen 70.

According to the above configuration, since the light emitting area 16a of the upper LED chip 11b is disposed on the non-light emitting area 16b of the lower LED chip 11b, the non-light emitting area 16b can be eliminated as the LED stack 12b. it can. Therefore, unevenness of the light emission pattern can be reduced, and unevenness of the illuminance distribution of the emitted light can be reduced.
Further, since the non-light emitting region 16b can be eliminated, the amount of emitted light can be increased approximately twice without increasing the area of the LED laminate 12b (without increasing the etendue).

The anode electrode 17p and the cathode electrode 17n are electrically connected to the anode mount portion 21p and the cathode mount portion 21n in the vicinity of one side of the LED chip 11b. Therefore, even if the LED chips 11b are stacked, by extending one side of the LED chip 11b to the side, charges can be injected into the LED chip 11b from the anode mount portion 21p and the cathode mount portion 21n to emit light. . In addition, the overlapping region of the LED chips 11b can be collected in the substantially central portion of the LED laminate 12b, and the region in which the unevenness of the light emission pattern is reduced can be disposed in the substantially central portion.
Further, since the cathode electrode 17n is formed of a transparent material such as ITO that transmits the light emitted from the light emitting region 16a, the colored light B emitted from the lower LED chip 11b is emitted upward without being blocked. Can do.

  Since the LED chip 11b is laminated using the adhesive material 20 having a refractive index substantially equal to that of the transparent substrate 14, the color light B emitted from the lower LED chip 11b is reflected at the boundary with the upper LED chip 11b and the LED. It is possible to prevent light from being confined in the stacked body 12b. That is, the colored light B emitted from the lower LED chip 11b can enter the upper LED chip 11b without being totally reflected, and can be emitted from the LED stack 12b. Therefore, it is possible to prevent light extraction loss due to light confinement in the LED laminate 12b.

  Since the stripe widths of the light emitting region 16a and the non-light emitting region 16b are formed to be substantially the same, the widths of the anode electrode 17p and the cathode electrode 17n disposed in both the regions 16a and 16b can also be made substantially the same. Therefore, the density of charges injected from both the electrodes 17p and 17n into the light emitting region 16a and the non-light emitting region 16b can be made uniform, and the charges can be supplied to the light emitting region 16a without excess or insufficient to emit light without waste. In addition, it is possible to prevent unevenness in the light emission pattern due to a part of the light emitting region 16a of the lower LED chip 11b and the upper LED chip 11b overlapping each other or a gap formed between the light emitting regions 16a.

  Further, by using the LED laminate 12b, unevenness in the illuminance distribution of the colored light B emitted from the light source device 10B can be reduced. Therefore, the length of the rod lens 30 that equalizes the illuminance distribution of the color light B emitted from the light source device 10B can be shortened, and the projector 1 can be miniaturized.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the light source devices 10R, 10G, and 10B have been described as being adapted to the light source of a three-plate projector, but are not limited to those adapted to this three-plate projector. It can be applied to light sources of various other types of projectors, such as a light source of a single-plate projector.

1 is a schematic configuration diagram of a projector according to an embodiment of the present invention. It is a schematic plan view of the light source device according to the present embodiment. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Projector, 10R, 10G, 10B ... Light source device (light source), 11r, 11g, 11b ... LED chip (light emitting body chip), 12r, 12g, 12b ... LED laminated body (light emitting body) ), 16a: light-emitting region, 16b: non-light-emitting region, 17p: anode electrode (electrode), 17n: cathode electrode (electrode), 40R, 40G, 40B ... liquid crystal light valve (light) Modulation device), 60... Projection lens (projection means)

Claims (6)

A light emitting body in which a plurality of light emitting chips having a light emitting area and a non-light emitting area for emitting light are laminated,
Laminating the light emitting chip so that the light emitting area of the other light emitting chip is arranged in the light emitting direction of the non-light emitting area of the one light emitting chip;
The non-light emitting region of the other light emitting chip stacked in the light emitting direction of at least one light emitting chip among the plurality of stacked light emitting chips transmits light. body. In the light emitting region and the non-light emitting region, electrodes for injecting charges into the light emitting chip are disposed,
The light emitting body according to claim 1, wherein at least the electrode disposed in the non-light emitting region is made of a material that transmits light emitted from the light emitting region. The electrode consists of one electrode and the other electrode,
The one electrode and the other electrode are disposed in the light emitting region and the non-light emitting region, respectively.
3. The light emitter according to claim 2, wherein the one electrode and the other electrode are electrically connected to an object to be mounted in a region near one side of the light emitter chip.   4. The light emitter according to claim 1, wherein an adhesive having substantially the same refractive index as that of the light emitter chip is filled between the stacked light emitter chips. 5. The light emitting region and the non-light emitting region are formed in a stripe shape alternately arranged,
The light emitting body according to any one of claims 1 to 4, wherein the light emitting region and the non-light emitting region have substantially the same stripe width. A projector comprising: a light source; a light modulation unit that modulates light from the light source; and a projection unit that projects light modulated by the light modulation unit,
A projector, wherein the light source comprises the light emitter according to any one of claims 1 to 5.

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