JP4909546B2 - Illumination device, light modulation device, and projection display device - Google Patents

Description

  The present invention relates to an illumination device, a light modulation device, and a projection display device, and more particularly to an illumination device, a light modulation device, and a projection display device that use light emitting diodes as light sources.

  In recent years, mobile devices such as notebook computers have become smaller and lighter, and the devices have become easier to carry, so presentations using projectors have become widespread. Progress is also being made. However, light source lamps such as halogen lamps and metal halide lamps that are normally used in projectors are relatively large and heavy. Therefore, light emitting diodes (hereinafter referred to as LEDs) are cited as light source lamps that can replace halogen lamps and metal halide lamps.

In recent years, LEDs have been actively developed, and the luminous efficiency of LED elements is rapidly improving, exceeding the luminous efficiency of discharge-type high-pressure mercury lamps and fluorescent lamps, which have been said to be the most efficient in the past. Is said to be a matter of time. LEDs generally have advantages such as long life, high efficiency, high G resistance, and monochromatic light emission, and are expected to be applied in many lighting fields. Various projectors using LEDs as light sources have been proposed. For example, a technique including a light emitting element array, a fly-eye lens, a liquid crystal panel, and a projection lens system has been proposed (see, for example, Patent Document 1). When attention is paid to the illumination device portion of the projector, the light emitted from the light emitting element is directly incident on the fly-eye lens. In addition, a technique including a light emitting element array, a micro lens array, a reduction optical device dichroic mirror, a two-dimensional micro deflection mirror array, and a projection optical system has been proposed (for example, see Patent Document 2). Paying attention to the illumination device part of the projector, the emitted light of the light emitting element is shaped by the micro lens array, but after shaping, the light beam width is narrowed and the light is directly guided to the two-dimensional micro deflection mirror array. . In addition, an image projection apparatus aiming at light utilization efficiency and miniaturization has been proposed (see, for example, Patent Document 3).
JP 2001-249400 A JP-A-11-32278 Japanese Patent Application Laid-Open No. 2002-244211

  However, the above techniques have the following problems.

  In general, the emitted light of an LED has different radiant intensity for each outgoing angle, and this intensity distribution is called a light distribution. When the configuration as described above is used, it is obvious that the light distribution characteristic of the LED appears as uneven illuminance on the liquid crystal panel or the two-dimensional micro deflection mirror array. Temporarily, with the technology configuration consisting of the above light emitting element array, fly-eye lens, liquid crystal panel, and projection lens system, using a bullet-type LED as the light source, increasing the directivity of the emitted light and lowering the divergence of the light, the light distribution Even if the influence of the characteristics is lowered, the NA (numerical aperture) of the fly-eye lens becomes too small to illuminate the entire liquid crystal panel.

  Further, the illumination unevenness has not been studied even in the technology of the image projection apparatus aiming at the light use efficiency and downsizing.

  The present invention solves such a problem, and provides an illumination device, a light modulation device, and a projection display device that can efficiently illuminate the entire light valve with little illuminance unevenness on a light valve such as a liquid crystal panel. It is to provide.

In order to achieve this object, the present invention has the following features.
  The lighting device according to the present invention is
  An illumination device having one or more light emitting elements, at least one condenser lens system, and at least one field lens system,
  The intensity of the light emitted from the light emitting element becomes weaker with an angle from the front of the light emitting direction, and the light emitted from the light emitting element is once converged by the condenser lens system and incident on the field lens system. The light is made almost parallel by the system and illuminates the illuminated surface.
  The condenser lens system is characterized by having a spherical aberration such that the passing region of the light beam increases as the distance from the optical axis increases.

The light modulation device according to the present invention includes:
  The illumination device described above is characterized by comprising light modulation means.

The projection display device according to the present invention is
  A projection type display device comprising the light modulation device described above,
  Each light emitting element includes a first emitting unit that emits light of a plurality of colors by a single light emitting element,
  A light modulator comprising a light valve driven in a time-sharing manner in synchronization with the emission timing of each color light emitted sequentially from the light emitting element;
  Projection means for projecting light modulated by the light modulation means.
  Moreover, it is a projection type display device provided with the light modulation device described above,
  Each light emitting element includes a second emitting unit that emits one color of light in a single light emitting element,
  A third emitting means for emitting three or more types of light emitting elements having different color lights;
  A light modulator comprising a light valve driven in a time-sharing manner in synchronization with the emission timing of each color light emitted sequentially from the light emitting element;
  Projection means for projecting light modulated by the light modulation means.
  Moreover, it is a projection type display device provided with the light modulation device described above,
  Each light emitting element has a plurality of surface light source means capable of emitting different color lights,
  A plurality of light modulation means comprising light valves for modulating each color light emitted from the surface light source means;
  Color synthesizing means for synthesizing the color lights modulated by the plurality of light modulating means;
  Projecting means for projecting the light synthesized by the color synthesizing means.
  Moreover, it is a projection type display device provided with the light modulation device described above,
  The light emitting element is a white LED, color filter light modulation means provided with a color filter that converts white light emitted from the LED into a plurality of colors, and
  Projecting means for projecting light modulated by the color filter light modulating means.

  According to the present invention, it is possible to provide an illuminating device, a light modulation device, and a projection display device that can illuminate the entire light valve efficiently with little illuminance unevenness on a light valve such as a liquid crystal panel.

  In the present invention, in an illuminating device arranged in the order of an LED, at least one condenser lens system, and at least one field lens system, the light distribution of the LED is utilized by utilizing the spherical aberration of the condenser lens system. It is characterized by canceling the characteristics. Hereinafter, an image forming apparatus and a search method according to an embodiment of the present invention will be described in detail with reference to the drawings. The embodiments described below are preferred embodiments of the present invention, and therefore technically preferable various kinds of limitations are given. However, the scope of the present invention is not limited to the following description. As long as there is no description which limits, it is not restricted to these aspects.

  First, if the field lens 2 has a sufficient aperture diameter, the light emitted from the focal plane of the field lens 2 illuminates the entire area of FIG. Here, a indicates a focal plane, and b indicates an illuminated surface. As shown in FIG. 2, the illuminating device according to the embodiment of the present invention once converges the emitted light of the LED 2 by the condenser lens 3, and arranges the convergence point on the focal plane a described with reference to FIG. If the condenser lens 3 is a non-aberration lens, there is no illuminance unevenness in the region shown in the figure. However, as shown in FIG. 3, the condenser lens 3 according to the embodiment of the present invention is given spherical aberration so that the light passing area becomes larger as the distance from the optical axis increases. As shown in FIG. 4, when the convergence point of the light beam passing near the optical axis is arranged at the focal point of the field lens 2, the light beam that has passed through the field lens 2 is emitted as parallel light. However, when the condenser lens 3 has spherical aberration as shown in FIG. 3, the light beam that has passed through the region away from the optical axis is not converted into parallel light but is emitted as a convergent light beam. This is because the light beam that has passed through the region away from the optical axis converges closer to the condenser lens 3 than the focal point of the field lens 2. In the configuration as shown in FIG. 4, when uniform light is incident on the condenser lens 3, the illuminated area in the figure has a distribution in which the illuminance gradually increases from the center of the area to the periphery as shown in the figure. become.

  On the other hand, as shown in FIG. 5, when an aberration-free condenser lens 3 and an LED 1 having a characteristic that gradually decreases with an angle from the front of the light emission direction are arranged, as shown in FIG. The illuminance distribution is directly affected by the light distribution characteristics of the LED 1. The illumination device according to the embodiment of the present invention, as shown in FIG. 6, by disposing the condenser lens 3 having the spherical aberration as shown in FIG. 3 on the LED 1 having the characteristics as described above, The aim is to cancel the light distribution characteristics of LEDs.

  That is, according to the above-described embodiment, a condenser lens having a spherical aberration in which the light passing region becomes larger as the distance from the optical axis increases with respect to the LED 1 having a characteristic of gradually weakening with an angle from the front of the light emitting direction. 3 is aimed at canceling the light distribution characteristics of the LED, and there is little illuminance unevenness on the light valve such as a liquid crystal panel, and the entire light valve can be illuminated efficiently.

  In addition, in a lighting device according to another embodiment of the present invention, a plurality of LEDs are arranged as shown in FIG. 7 in response to a case where the amount of light of one LED is insufficient. A plurality of LEDs (LED array 5), a plurality of condenser lenses (lens array 6), and a field lens 2 (one) are arranged in this order from the light source side to the illuminated surface side. In order to give desired spherical aberration characteristics to the light emitted from the LED 1 and to extract light efficiently, it is desirable to dispose the condenser lens 3 for each LED. In this case, the amount of aberration of the field lens 2 is considered (in general, the aberration outside the optical axis is larger than the aberration on the optical axis), and the same effect as that obtained by the spherical aberration of the condenser lens 3 on the optical axis. Therefore, it is desirable to change the aberration amount of the condenser lens 3 on the optical axis and off the optical axis.

  Furthermore, when the field curvature of the field lens 2 is large, it is conceivable to arrange the secondary light source formed by the condenser lens 3 with an inclination approximate to the field curvature curve 7 as shown in FIG.

  Various methods for performing color display on the projection display device using the illumination device as described above are conceivable. Broadly speaking, there are a method of performing color display by crafting a light valve and a method of performing color display by mixing a plurality of color lights with an illumination optical system including a light source. As a method of crafting a light valve, for example, a method using a color filter, a method in which three subpixels of red / green / blue are made to correspond to one microlens (Television Society Technical Report VOL.19, NO.8, IDY95-41), but at the expense of brightness and resolution. As a method of mixing multiple colored lights with an illumination optical system that includes a light source, each LED illuminates the entire light valve, so use an LED that contains red / green / blue chips in one element. Method. Red / green / blue LEDs that emit each color are arranged and mixed on the light valve, or red / green / blue, each LED is arranged for each color, red surface light source, green surface light source, There is a method in which a blue surface light source is made and each emitted light is mixed with a prism or the like.

  Moreover, if the illuminating device which concerns on embodiment of this invention is used, a small display apparatus can be comprised besides a projection type display apparatus. The simplest configuration is a simple display device in which a liquid crystal light valve is combined with the illumination device of the present invention.

  As a result, the image on the liquid crystal plate can be read, and a magnifying glass such as a magnifying glass or an eyepiece optical system that can be directly attached to the eyes can be combined.

  FIG. 9 is a schematic view of a lighting device according to another embodiment of the present invention. From the light source side to the surface to be illuminated, the LEDs 1 (one), the condenser lens group 8 (three convex lenses), the field lens 2 (one), and the liquid crystal light valve 10 are arranged in this order (FIG. 9). In order to efficiently extract the light emitted from the LED 1, it is necessary to set the NA (numerical aperture) of the condenser lens group 8 bright. Therefore, the condenser lens group 8 has a three-lens configuration as shown in the figure. The spherical aberration of the condenser lens group 8 when the position of the LED 1 is an object point is such that the convergence point gradually shifts toward the object point side as shown in FIG. Of the light emitted from the LED, the paraxial light beam converges on the focal plane of the field lens 9 in FIG. 9, and the peripheral light beam converges on the condenser lens group 8 side of the focal plane and enters the field lens 9. Led to. At this time, since the light passing through the outermost periphery of the field lens 9 is weakly converged in the optical axis direction by the field lens 9 as described above, the outermost periphery of the range illuminated by the field lens 9 is It will be extremely dark. This is shown in FIG. 11 in the lens system shown in FIG. As can be seen from the illuminance distribution curve 4, there is a drop in illuminance at the edge of the liquid crystal surface. Therefore, by disposing the liquid crystal light valve so that it does not enter the range of the outermost periphery, it is possible to illuminate the entire surface of the liquid crystal light valve without unevenness.

  FIG. 12 is a schematic view of a lighting device according to another embodiment of the present invention. In the present embodiment, for the purpose of improving the illuminance on the liquid crystal light valve, the LEDs are arranged in 5 rows and 1 column. In this embodiment, the LED array 5, the condenser lens group array group (each condenser lens group 8 has three convex lenses), the relay lens 10 (one piece), the field lens 2 from the light source side to the illuminated surface side. (One sheet) and the liquid crystal light valve 9 are arranged in this order. By disposing the relay lens 10, it is possible to efficiently extract LED light disposed outside the optical axis of the field lens 2 (FIG. 12). The spherical aberration characteristics of each condenser lens group 8 are the same as those in the embodiment described with reference to FIG.

  By combining the projection optical system with the illumination optical system described above, it is possible to configure a projection display device that is small in size and saves energy and has little illuminance unevenness.

  As mentioned above, the invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. Needless to say.

It is a figure which shows a mode that it radiate | emits from the field lens of the illuminating device which concerns on embodiment of this invention. It is a block diagram of the illuminating device which concerns on embodiment of this invention. It is a figure which shows that the condenser lens of the illuminating device which concerns on embodiment of this invention has spherical aberration. It is a block diagram of the illuminating device which concerns on embodiment of this invention. It is a block diagram of the illuminating device which concerns on embodiment of this invention. It is a block diagram of the illuminating device which concerns on embodiment of this invention. It is a block diagram of the illuminating device which concerns on embodiment of this invention. It is a block diagram of the illuminating device which concerns on embodiment of this invention. It is a block diagram of the illuminating device which concerns on embodiment of this invention. It is a figure which shows a mode that a convergence point has shifted | deviated in the condenser lens of the illuminating device which concerns on embodiment of this invention. It is a block diagram of the illuminating device which concerns on embodiment of this invention. It is a block diagram of the illuminating device which concerns on embodiment of this invention.

Explanation of symbols

1 LED
2 Field lens 3 Condenser lens 4 Illuminance distribution curve 5 LED array 6 Lens array 7 Field lens field curvature curve 8 Condenser lens group 9 Liquid crystal light valve 10 Relay lens a Focal plane b Illuminated surface

Claims (12)

One or a plurality of light emitting elements, a lighting device comprising at least one condenser lens system, and at least one field lens system, and
The intensity of the light emitted from the light emitting element is weakened as an angle from the light emitting direction front, the light emitted from the light emitting element, the once converged by the condenser lens system is incident on the field lens system, the field lens The light is made almost parallel by the system and illuminates the illuminated surface .
The condenser lens system has a spherical aberration such that a light passing region increases as the distance from the optical axis increases . The light emitting element, the condenser lens system, is composed in the order of the field lens system, a secondary light source image of the light emitting device produced by the condenser lens system is characterized in that positioned in the focus of the field lens system The lighting device according to claim 1. Lighting apparatus according to claim 1 or 2, wherein the intensity distribution of the light emitted from the light emitting element is a Lambertian distribution. When arranging a plurality of the light emitting element, the condenser lens system, the illumination device according to any one of claims 1 to 3, characterized in that it is arranged in a one-to-one correspondence to the respective light emitting element . Claims, characterized in that it has a relationship of NA (C) ≧ NA (F ) between the numerical aperture of the condenser lens system [NA (C)] and a numerical aperture of the field lens system [NA (F)] Item 5. The lighting device according to any one of Items 1 to 4 . The lighting device according to claim 1, any one of 5, the optical modulation apparatus characterized by having a light modulating means. Wherein between the condenser lens system and said light modulating means, optical modulator device according to 6, wherein the outgoing light having a polarization converting element for aligning in one direction of polarization of the light emitting element. A projection type display device comprising the light modulation device according to claim 6 ,
Each light emitting element includes a first emitting unit that emits light of a plurality of colors by a single light emitting element,
A light modulator comprising a light valve driven in a time-sharing manner in synchronization with the emission timing of each color light emitted sequentially from the light emitting element;
And a projection unit that projects the light modulated by the light modulation unit. A projection type display device comprising the light modulation device according to claim 6 ,
Each light emitting element includes a second emitting unit that emits one color of light in a single light emitting element,
A third emitting means for emitting three or more types of light emitting elements having different color lights;
A light modulator comprising a light valve driven in a time-sharing manner in synchronization with the emission timing of each color light emitted sequentially from the light emitting element;
And a projection unit that projects the light modulated by the light modulation unit. A projection type display device comprising the light modulation device according to claim 6 ,
Each light emitting element has a plurality of surface light source means capable of emitting different color lights,
A plurality of light modulation means comprising light valves for modulating each color light emitted from the surface light source means;
Color synthesizing means for synthesizing the color lights modulated by the plurality of light modulating means;
Projection display device characterized by and a projection means for projecting the synthesized light by the color synthesizing means. A projection type display device comprising the light modulation device according to claim 6 ,
The light emitting element is a white LED, color filter light modulation means provided with a color filter that converts white light emitted from the LED into a plurality of colors, and
Projection means for projecting light modulated by the color filter light modulation means. Between said light modulating means and said condenser lens system, projection of any one of claims 8 to 11, characterized in that it has a polarization conversion element to align the light emitted from the light emitting element in one direction of polarization Type display device.

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