KR20090025130A - Illumination system and projection system employing the same - Google Patents

Abstract

A lighting device and a projection device using the same are provided to reduce a size and weight of a whole system by using a plurality of dichroic filters which is arranged by turns. A lighting device(100) comprises a plurality of light source units(110), a condenser(120), a color combination unit(130), and a relay optical system(140). The light source units are composed of an array of a plurality of LEDs(112) having a common light emitting surface(110a). The condenser is faced with each light source unit, emits a uniform light by mixing a light of the light source units, includes an input surface(120a), a side surface(120b), and an output surface(120c), and is made of a transparent member having a high refractive index. The color combination unit synthesizes a light of different color emitted in each light source unit, and is composed of two dichroic filters.

Description

Lighting device and projection device employing the same {Illumination system and projection system employing the same}

FIELD OF THE INVENTION The present invention relates to optical systems, and in particular, to lighting devices that can be used in various projection systems such as projectors or projection TVs.

In recent years, lighting systems based on color light-emitting diodes (LEDs) have been widely used, whereby generally red, green, and blue light are used in combination and synthesize light from a light collector and an LED group. Optical tools are used to do this.

1 is a projection illumination device disclosed in Japanese Laid-Open Patent Publication 2000-180962. According to the drawing, the illumination device is arranged to face the LED group (1), the LED group (1), which emits red, green, and blue light, in order to provide uniform light to the illuminated surface. Three transparent blocks 10 which uniformly mix the light from 1), a dichroic prism 4 and a dichroic prism 4 which are in the form of a cube and synthesize the light from the LED group 1 And a condenser lens 6 for transmitting the light to the surface to be illuminated which becomes the working surface of the optical modulator 8. This projection illuminator uses a cube-shaped dichroic prism 4, which is heavy in weight and high in manufacturing cost.

The illumination system disclosed in US published patent US 2007/0064202 includes three LED groups and three condensers, and relay optics for synthesizing light from the three LED groups and delivering them to an illuminated surface, the relay optics comprising three LEDs. Three collector optics, each facing the group, two dichroic filters for synthesizing light in the three LED groups, and coupling optics. The lighting system uses a dichroic filter that is lighter in weight and less expensive to manufacture than a dichroic cube.

However, in the above lighting system, two dichroic filters are spaced apart from each other, and also require many optical components to maintain high light efficiency, thereby increasing the overall system size.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to reduce the size and weight of a system and the complexity of a manufacturing process, and to provide a lighting apparatus having a high light efficiency and a projection system employing the same.

Illumination apparatus according to an embodiment of the present invention comprises a plurality of light source units; A plurality of light collectors disposed to face each of the plurality of light source units and having an input surface, a side surface, and an output surface; A color synthesizing unit synthesizing light emitted from the plurality of light collectors, the color synthesizing unit including two dichroic filters disposed to cross each other; And a relay optical system for transmitting the light synthesized in the color synthesizing unit to an illuminated surface.

Each of the plurality of light source units may be configured as an array of a plurality of LEDs having a common light emitting surface.

The light emitting surface and the input surface are spaced apart from each other, and the distance between the light emitting surface and the input surface may be 0.0001h or more when the minimum opening of the LED array is h.

The color synthesizing unit may include a red dichroic filter composed of one plate and a blue dichroic filter composed of two plates.

The focal plane of the relay optical system may be formed at a distance of 0.05H or more from the illuminated plane when the minimum opening of the illuminated plane is H.

The condenser may have an angle formed between the input surface and the side surface larger than 90 °.

The cross-sectional shape of the light collector may be formed to be the same as the shape of the illuminated surface.

The output surface of the condenser may be convex or spherical in shape.

Projection apparatus according to an embodiment of the present invention comprises a lighting apparatus according to an embodiment of the present invention; An optical modulator for modulating the light transmitted from the relay optical system of the illumination device to form an image, the optical modulator being disposed such that an operating surface is located on the illuminated surface; And a projection optical system for projecting an image formed by the optical modulator.

As the optical modulator, a reflective display device such as a micro mirror device may be employed.

The lighting apparatus according to the embodiment of the present invention employs a plurality of dichroic filters intersected to effectively reduce the size and weight of the entire system. In addition, the light collecting efficiency is improved by improving the shape and arrangement of the light collector, and the focal plane of the relay optical system is formed to be spaced apart from the illuminated surface, thereby improving light uniformity on the illuminated surface.

The projection apparatus according to the embodiment of the present invention can implement a high quality image with a simple system configuration by employing such an illumination device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of description.

Figure 2a schematically shows a lighting apparatus according to an embodiment of the present invention, Figures 2b and 2c is a view illustrating a minimum opening for each of the light source unit and the illuminated surface of Figure 2a.

Referring to the drawings, the lighting apparatus 100 according to an embodiment of the present invention is for illuminating the light on the illuminated surface (S1), facing a plurality of light source unit 110, each of the plurality of light source unit 110. Concentrator 120, a color synthesizing unit 130 for synthesizing the light emitted from the plurality of concentrators 120, and a relay for transmitting the light synthesized in the color synthesizing unit 130 to the illuminated surface S1. The optical system 140 is included.

The light source unit 110 consists of an array of a plurality of LEDs 112 having, for example, a common light emitting surface 110a. In the figure, three light source units 110 are shown, each provided with light of different colors, for example, red, green, blue light. In addition to the LED, the light source unit 110 may employ other light source elements, for example, a laser diode (LD).

The light collector 120 is disposed to face each of the plurality of light source units 110, and collects the light from the light source unit 110 so that the light is uniformly mixed, collimated, and outputs the light. The light collector 120 includes an input surface 120a through which light from the light source unit 110 is incident, a side surface 120b for totally reflecting and mixing light, and an output surface 120c for emitting the mixed light. The input surface 120a may be parallel to the light emitting surface 110a of the light source unit 110 and may be spaced apart by a distance d. The separation of the light emitting surface 110a from the input surface 120a of the light collector 120 is to collect the light emitted from the light emitting surface 110a on the light collector 120 more effectively. The spaced distance d may be greater than approximately 0.0001 h when the minimum opening of the light source unit 110 is h. The distance d may be 0.01 μm or more. Here, the minimum opening means the shorter length of the opening dimensions formed by the LED 112 array, as shown in FIG. 2B.

The light collector 120 is made of a transparent member having a relatively large refractive index, and is formed using, for example, acrylic resin, glass, or other transparent material. The larger the refractive index of the material constituting the light collector 120, the smaller the angle of refraction of the light refracted on the input surface 120a, and the larger the angle of incidence on the side surface 120b, so that the efficiency of total reflection of the light on the side surface 120b increases. In addition, in the present invention, the angle formed between the side surface 120b and the input surface 120a is made larger than 90 ° so that the light incident through the input surface 120a is incident on the side surface 120b at a larger angle of incidence. . Therefore, the total reflection efficiency at the side surface 120b becomes higher.

The light incident on the light collector 120 is totally reflected at the side surface 120b and then mixed and emitted through the output surface 120c. At this time, the output surface 120c is convex toward the traveling path of the light for collimating the emitted light. It can be formed in a shape. The output surface 120c may have a spherical shape, for example.

The input surface 120a and the output surface 120c of the light collector 120 are formed along the shape of the illuminated surface S1. For example, the cross-sectional shape of the light collector 120 may be the same as that of the illuminated surface S1. Can be formed equally.

The color synthesizing unit 130 synthesizes light of different colors emitted from each light source unit 110. In the present invention, the color synthesis unit 130 is composed of two dichroic filters arranged to cross each other. The two dichroic filters may be, for example, one plate of red dichroic filter 132 and two plates of blue dichroic filter 134. This configuration of color synthesizing unit 130 is chosen to reduce the weight and size of the overall system as much as possible.

On the other hand, the light can transmit the color synthesis unit 130 non-uniformly by such a configuration. The red dichroic filter 132 consists of one plate, while the blue dichroic filter 134 is divided into two plates and separated from each other, unworking the filter in the blue or green channel. This is because areas can be created. The size of this non-operation area is approximately the thickness of the plate.

This non-uniform transmission of light may affect luminance uniformity in the illuminated surface S1, and in order to reduce this effect, the light synthesized in the color synthesizing unit 130 may be transmitted to the illuminated surface S1. The focal plane S2 of the relay optical system 140 is formed behind the illuminated surface S1. The relay optical system 140 may be composed of, for example, one or more lenses, and as illustrated, the configuration is such that the focal plane S2 of the relay optical system 140 is spaced apart from the illuminated surface S1 by a distance D. Can be decided. The distance D may be 0.05H or more when the minimum opening of the illuminated surface S1 is H. As shown in FIG. 2C, the illuminated surface S1 can be, for example, the working surface of an optical modulator in which display elements are arranged in a two-dimensional array, where the minimum opening H is the opening formed by this array. The shorter side in the dimension.

The lighting apparatus according to the embodiment of the present invention has a numerical aperture (NA) of about 0.25 and exhibits about 35% or more light efficiency and 80% or more light uniformity.

3 shows a schematic configuration of a projection apparatus 200 according to an embodiment of the present invention. Referring to the drawings, the projection apparatus 200 synthesizes a plurality of light source units 110, a light collector 120 facing each of the light source units 110, and light emitted from the plurality of light collectors 120. The color synthesizing unit 130, the relay optical system 140 for transmitting the light synthesized in the color synthesizing unit 130 to the illuminated surface S1, and the optical modulator 150 for modulating the light transmitted from the relay optical system to form an image. And a projection optical system 160 for projecting the image formed by the optical modulator 150 onto the projection surface.

In addition, although not shown, the projection apparatus 200 includes known control means such as a light emission control unit for controlling the light emission timing of the light source unit 110 and a modulation element control unit for controlling the driving of the optical modulator 150 in accordance with an image signal. It will be provided.

Here, the light source unit 110, the light collector 120, the color combining unit 130, and the relay optical system 140 constitute a lighting device 100 according to the embodiment of the present invention described with reference to FIG. 2A, and thus, a detailed description thereof. Is omitted.

The light modulator 150 modulates light to form an image, and the light modulator 150 is disposed so that the working surface becomes the illuminated surface S1. As the optical modulator 150, a reflective display device may be employed. The reflective display element displays an image by spatially modulating the light to be illuminated by controlling the reflection characteristics of a plurality of display elements arranged in a two-dimensional array on the illuminated surface S1. For example, a device such as a DMD (Digital Micro Mirror Device) in which a micromirror is arranged in a two-dimensional lattice shape in which the inclination angle is changed into two types of inclination angles in an ON state and an OFF state is reflected by an image signal. It can be employed as a type display element. In the drawing, a micromirror element is used as the optical modulator 150. Accordingly, the light reflected from the micromirror having an inclination angle corresponding to the ON state is incident to the projection optical system 160. Although reflected from the micromirror having an inclination angle corresponding to the OFF state, the light is not shown, but the image is formed by facing the direction not incident on the projection optical system 160.

The projection optical system 160 projects an image formed by the optical modulator 150 onto a projection surface (not shown). For example, the projection optical system 160 may include one or more lenses.

Although the light in the light modulator 150 is shown to be directed directly to the projection optical system 160, if necessary, for example, the optical path from the relay optical system 140 toward the optical modulator 150 and the optical modulator 150. An optical path changing member may be further provided on the optical path between the optical modulator 150 and the projection optical system 160 so that the light path at 150 may not overlap the optical path toward the projection optical system 160.

In addition, the optical modulator 150 may employ liquid crystal on silicon (LCOS), which is a reflective liquid crystal display, as the reflective display device, and in this case, a view from the relay optical system 140 to the optical modulator 150. A beam splitter for separating the optical path from the furnace and the optical modulator 150 to the projection optical system 160 may be further provided.

The present invention has been described with reference to the embodiments shown in the drawings for ease of understanding, but this is merely exemplary, those skilled in the art that various modifications and equivalent other embodiments are possible from this. I will understand. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

1 shows a projection illumination device disclosed in Japanese Laid-Open Patent Publication 2000-180962.

Figure 2a schematically shows a lighting apparatus according to an embodiment of the present invention, Figures 2b and 2c is a view illustrating a minimum opening for each of the light source unit and the illuminated surface of Figure 2a.

3 schematically shows a projection apparatus according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100. Lighting unit 110 ... Light source unit

112 LED 120 Concentrator

130 ... color synthesis unit 132 ... red dichroic filter

134 ... Blue dichroic filter 140 ... Relay optics

150 ... optical modulator 160 ... projection optics

200 ... projection unit

Claims (15)

A plurality of light source units; A plurality of light collectors disposed to face each of the plurality of light source units and having an input surface, a side surface, and an output surface; A color synthesizing unit synthesizing light emitted from the plurality of light collectors, the color synthesizing unit including two dichroic filters disposed to cross each other; And a relay optical system for transmitting the light synthesized in the color synthesizing unit to an illuminated surface. The method of claim 1, Each of the plurality of light source units, An illumination device comprising a plurality of arrays of LEDs having a common emitting surface. The method of claim 2, And the light emitting surface and the input surface are spaced apart from each other. The method of claim 3, And the distance between the light emitting surface and the input surface is 0.0001 h or more when the minimum opening of the LED array is h. The method of claim 1, The color synthesizing unit comprises a red dichroic filter consisting of one plate and a blue dichroic filter consisting of two plates. The method of claim 1, And the focal plane of the relay optical system is formed at a distance of 0.05H or more from the illuminated plane when the minimum opening of the illuminated plane is H. The method of claim 1, The light collector is characterized in that the angle formed between the input surface and the side is greater than 90 °. The method of claim 1, The cross-sectional shape of the light collector is the same as the shape of the surface to be illuminated. The method according to any one of claims 1 to 8, The output surface of the light collector is characterized in that the convex shape. The method of claim 9, Illumination apparatus, characterized in that the output surface of the condenser is spherical shape. The lighting device of any one of claims 1 to 8; An optical modulator for modulating the light transmitted from the relay optical system to form an image, the optical modulator being disposed such that an operating surface is located on the illuminated surface; And a projection optical system for projecting an image formed by the optical modulator. The method of claim 11, And the optical modulator is a reflective display element. The method of claim 12, And the reflective display element is a micro mirror element. The method of claim 11, And the output surface of the condenser is convex. The method of claim 11, And the output surface of the condenser is spherical in shape.

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