JP2022072582A - Light source device and image projector with the same - Google Patents

Abstract

To provide a small and still efficient light source device, and an image projector with the light source device.SOLUTION: A light source device 100 includes: a light source unit 10 having a plurality of light sources 1b and a collimator lens 2 for making light beams from the light sources 1b into parallel light beams; an optical characteristics conversion element 20 for generating light with different characteristics from the characteristics of the light from the light source 10; and an optical system for irradiating the optical characteristics conversion element 20 with the light from the light source unit 10. The optical system includes a division element 3 and a light collecting element 4 arranged in that order from the light source unit 10 side to the optical characteristics conversion element 20 side, the division element dividing the light from the light source unit 10 and the light collecting element 4 collecting a plurality of lights divided by the division element 3. The focal distance of the division element 3 and the distance between the division element 3 and the light collecting element 4 are each properly set.SELECTED DRAWING: Figure 2

Description

The present invention relates to a light source device and an image projection device having the same.

In recent years, in an image projection device (projector), from the viewpoint of long life and high added value, light from a high-power laser diode (excitation light source) is irradiated to a phosphor as excitation light, and wavelength-converted fluorescent light is used as a light source. Attention is being paid to the method used as.

The emission point of the high-power laser diode has a high light density, and when the excitation light is directly incident on the wavelength conversion device, fluorescence light corresponding to the amount of the excitation light cannot be obtained due to luminance saturation. Patent Document 1 discloses a light source device that equalizes the irradiation distribution on a phosphor in order to reduce the light density.

Japanese Unexamined Patent Publication No. 2018-189886

However, the light source device of Patent Document 1 has a large number of parts and becomes large in size.

An object of the present invention is to provide a light source device having high efficiency while being small in size and an image projection device having the same.

The light source device as one aspect of the present invention has a light source unit including a plurality of light sources and a collimeter lens that converts light rays from the plurality of light sources into parallel light sources, and light characteristics that generate light having different characteristics from the light from the light source unit. It has a conversion element and an optical system that irradiates the light characteristic conversion element with light from the light source unit, and the optical system is arranged in order from the light source unit side to the optical characteristic conversion element side, and the light from the light source unit. When the focal distance of the dividing element is f and the distance between the dividing element and the condensing element is L, which includes a dividing element for dividing the light and a condensing element for condensing a plurality of lights divided by the dividing element. ,
f / L ≧ 1.0
It is characterized by satisfying the conditional expression.

Further, the light source device as another aspect of the present invention generates light having different characteristics from the light from the light source unit and the light source unit including the collimeter lens that converts the light rays from the plurality of light sources and the light sources into parallel light sources. It has an optical characteristic conversion element and an optical system that irradiates the optical characteristic conversion element with light from the light source unit, and the optical system has a first optical surface that divides the light from the light source unit on the side of the light source unit. It is characterized by including an optical element provided with a second optical surface for condensing a plurality of lights divided by the first optical surface on the side of the optical characteristic conversion element.

According to the present invention, it is possible to provide a light source device having high efficiency while being small in size and an image projection device having the same.

It is a block diagram of the image projection apparatus which has the light source apparatus which concerns on embodiment of this invention. It is a block diagram of the light source apparatus of Example 1. FIG. It is a figure which shows the optical principle of Example 1. FIG. It is a figure which shows the optical principle of Example 1. FIG. It is a figure which shows the optical principle of Example 1. FIG. It is a figure which shows the modification of the light source apparatus of Example 1. FIG. It is a figure which shows the optical principle of Example 1. FIG. It is a figure which shows the illumination distribution at a condensing point. It is a figure which shows the modification of the light source apparatus of Example 1. FIG. It is a figure which shows the modification of the light source apparatus of Example 1. FIG. It is a perspective view of a light source. It is a light distribution diagram of a light source. It is a figure which shows the modification of the light source apparatus of Example 1. FIG. It is a figure which shows the spectrum of the light emitted from the light source apparatus of FIG. It is a figure which shows the modification of the light source apparatus of Example 1. FIG. It is a figure which shows the modification of the light source apparatus of Example 1. FIG. It is a block diagram of the display device of Example 2. It is a block diagram of the image projection apparatus which has the display apparatus of Example 2.

Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In each figure, the same member is given the same reference number, and duplicate description is omitted.

In the drawings described below, the number, dimensions, ratios, etc. of the members are appropriately different for easy viewing.

FIG. 1 is a block diagram of a projector (image projection device) having a light source device 100 according to an embodiment of the present invention. The white light 100a emitted from the light source device 100 is converted into illumination light 200a by the illumination optical system 200 and incident on the light modulation element 300. The illumination optical system 200 converts the white light 100a as unpolarized light from the light source device 100 into linearly polarized light, or converts it into light that forms an irradiation region having uniform brightness on the light modulation element 300, or RGB. The illumination light 200a is generated by separating the light into the three colors of light.

The light modulation element 300 is composed of a transmissive or reflective liquid crystal panel, a digital micromirror device, or the like. The drive circuit 600 drives the light modulation element 300 according to an image signal input from the outside. The light modulation element 300 modulates the illumination light 200a according to the image signal to generate the image light 300a. The image light 300a is projected onto the projected surface 500 such as a screen via the projection optical system 400. The projection optical system 400 synthesizes the color-separated image light 300a and magnifies the image light 300a. As a result, the projected image as a color image is displayed.

FIG. 2 is a block diagram of the light source device 100 of this embodiment. The light source device 100 includes a light source unit 10, an optical system, and a wavelength conversion element (optical characteristic conversion element) 20.

The light source unit 10 has a plurality of light sources 1b and a collimator lens 2. The plurality of light sources 1b emit blue light as excitation light. The collimator lens 2 has a positive power and converts the luminous flux from the plurality of light sources 1b into a parallel luminous flux. The collimator lens 2 may be a single lens or an array-shaped integrated lens.

The optical system includes a lens array element (dividing element) 3 and a condenser lens (condensing element) 4 arranged from the light source unit 10 side to the wavelength conversion element 20 side. The lens array element 3 is composed of a plurality of element lenses, and divides a parallel light flux from the light source unit 10. The condenser lens 4 collects the light flux divided by the lens array element 3 at the focal position on the optical axis of the condenser lens 4. By having such an optical system, the luminance distribution of the parallel light flux from the light source unit 10 is made uniform. Therefore, by arranging the wavelength conversion element 20 at the focal position on the optical axis of the condenser lens 4, it is possible to form a luminous flux having a uniform luminance distribution on the wavelength conversion element 20. The wavelength conversion element 20 may be a transmission type or a reflection type.

Hereinafter, the function of the lens array element 3 will be described in detail. 3 to 5 are diagrams showing an optical principle, and schematically show a so-called tandem optical system in which a lens array element 3 and a condenser lens 4 are arranged so as to face each other. In the tandem optical system, when an object is placed at the front focal length of the lens array element 3, the magnification of the image formed on the wavelength conversion element 20 is the distance L between the two lens systems as shown in FIG. It is determined independently by the ratio of the focal lengths of the two lens systems (-f1 / f2'). Here, f1 and f2'are the focal lengths of the lens array element 3 and the condenser lens 4, respectively. That is, in this embodiment, as shown in FIG. 5, when the focal length of the lens array element 3 is f and the distance between the lens array element 3 and the condenser lens 4 is L, the following relationship is satisfied.

f / L ≧ 1.0
By satisfying the above relationship, the light source device 100 can be significantly downsized.

Further, since the imaging magnification is determined by the focal length of the lens array element 3, the lens array element 3 is configured such that the focal length is constant and only one surface has a light-collecting action as shown in FIG. You may.

As shown in FIG. 3, the object imaged on the wavelength conversion element 20 is an aerial cross section of the light from the light source unit 10. That is, the wavelength conversion element 20 has a conjugate relationship with the aerial cross section of the light from the light source unit 10. When the parallelism of the parallel light flux from the light source unit 10 is high, the shape of the image is similar to the shape of the element lens of the lens array element 3. If a compression optical system or the like is provided between the light source unit 10 and the lens array element 3, the parallelism of the light flux incident on the lens array element 3 is lowered. In this case, the image formed on the wavelength conversion element 20 as shown in FIG. 7 is formed at a position different from that of the parallel light rays, so that the distribution is not uniform as shown in FIG. When the parallelism of the light flux incident on the lens array element 3 is low, a uniform luminance distribution can be formed on the wavelength conversion element 20 by using two lens array elements 3 in pairs, but the light source device 100 can be used. It will be large.

In this embodiment, the light source 1b is close to an ideal point light source. That is, the parallelism of the light flux that is parallelized by the collimator lens 2 and emitted from the light source unit 10 is considerably high. Therefore, when the width of the light from the light source unit 10 is A and the width of the light incident on the lens array element 3 is B, it is desirable to satisfy the following conditional expression (1).

0.90 ≤ B / A ≤ 1.10 (1)
By satisfying the conditional expression (1), a uniform luminance distribution can be formed on the wavelength conversion element 20.

The parallelism of the light from the light source unit 10 varies in the manufacturing process. When the area of the image formed on the wavelength conversion element 20 increases or decreases, the amount of emitted fluorescent light changes. Therefore, it is desirable to shorten the distance between the light source unit 10 and the lens array element 3 as much as possible. Therefore, it is preferable that the numerical range of the conditional expression (1) is the numerical range of the following conditional expression (1a).

0.95 ≤ B / A ≤ 1.05 (1a)
Further, considering the color unevenness due to superposition, it is more desirable to set the numerical range of the conditional expression (1) to the numerical range of the following conditional expression (1b).

0.98 ≤ B / A ≤ 1.02 (1b)
The optical system in the light source device 100 includes the lens array element 3 and the condenser lens 4 in this embodiment, but may include an optical element 5 having the functions of these elements as shown in FIG. The optical element 5 is provided with a lens array surface (first optical surface) that divides the light from the light source unit 10 on the side of the light source unit 10, and the light divided by the lens array surface is provided on the side of the wavelength conversion element 20. A condenser lens surface (second optical surface) for condensing light is provided. By providing the optical element 5 having the functions of the two elements instead of providing the lens array element 3 and the condenser lens 4, the light source device 100 can be further miniaturized.

Further, although the light source device 100 has one light source unit 10 in this embodiment, it may have two light source units 10a and 10b as shown in FIG. In this case, the light source device 100 has a luminous flux combining element 30. As shown in FIG. 11, light is emitted from one surface of the light source 1b along the Z direction. Since the emitted light is linearly polarized and has different divergence angles in the X and Y directions, the luminous flux cross section of the XY cross section perpendicular to the Z axis is elliptical. Since the elliptical light flux cross section is parallelized by the same collimator lens 2, the light flux widths of the YZ cross section and the XZ cross section are different as shown in FIG. At this time, by shifting the phases of the two light source units 10a and 10b by 90 degrees with respect to their respective light emission axes, as shown in FIG. 10, a narrow luminous flux from the light source unit 10b is emitted from the light source unit 10a. It can be included in a wide luminous flux. That is, the luminous flux from each light source unit can be incident on the lens array element 3 without widening the luminous flux width. The luminous flux synthesis element 30 may be a comb-shaped mirror, a comb-shaped dichroic mirror, or a PBS (Polarising Beam Splitter).

In a projector, color reproduction based on a color standard such as sRGB or DCI may be required. However, a material having an appropriate emission spectrum as a material for a phosphor has not yet been put into practical use. Therefore, as shown in FIG. 13, in order to improve the color rendering property, instead of the light source 1b in which the light source unit 10b emits blue light, a light source 1g that emits green light and a light source that emits red light are emitted as auxiliary light sources. It is useful to have 1r. With such a configuration, the spectrum shown in FIG. 14 can be obtained. Since the wavelength conversion element 20 has an absorption spectrum only at the wavelength of the excitation light, the color light other than the blue light from the light source 1b is transmitted and reflected without being absorbed. Therefore, it is possible to superimpose and utilize the fluorescent light whose wavelength is converted by the excitation light and the colored light from the light sources 1g and 1r.

Further, the image formed on the wavelength conversion element 20 is one in this embodiment, but the present invention is not limited to this. As shown in FIG. 15A, by arranging a plurality of condenser lenses 4a, 4b, 4c, a plurality of images may be formed on the wavelength conversion element 20. The heat source can be dispersed by forming a plurality of images formed on the wavelength conversion element 20 instead of one. Although the wavelength conversion element 20 is configured as one member in FIG. 15, it may be configured by a plurality of members. Further, as shown in FIG. 15B, there is no limitation on the number of images formed on the light source 1b and the wavelength conversion element 20. Further, as shown in FIG. 15C, it is possible to further separate the heat source by eccentricizing the optical axes of the condenser lenses 4a and 4b.

Further, instead of providing the lens array element 3 and the condenser lens 4 in the configuration of FIG. 15, an optical element 6 having the functions of the lens array element 3 and the condenser lens 4 may be provided as shown in FIG. The optical element 6 is provided with a lens array surface (first optical surface) that divides the light from the light source unit 10 on the light source unit 10 side, and the light divided by the lens array surface is provided on the wavelength conversion element 20 side. It includes a lens array surface (second optical surface) that collects light. When the number of element lenses on the lens array surface that divides light is α and the number of element lenses on the lens array surface that collects light is β, the relationship α> β is satisfied. By providing the optical element 6 having the functions of the two elements instead of providing the lens array element 3 and the condenser lens 4, the light source device 100 can be further miniaturized.

FIG. 17 is a configuration diagram of the display device 700 of this embodiment. The display device 700 includes a light source device 100A, an illumination optical system 200A, and a light modulation element 300. In the display device 700, the light modulation element 300 is directly illuminated by the light from the light source device 100A.

The light source device 100A includes a light source 1B that emits blue light, a light source 1G that emits green light, and a light source 1R that emits red light. The light emitted from the plurality of light sources is incident on the collimator lens 2. The collimator lens 2 may be a single lens, an array-shaped integrated lens, or may have its position and focal length changed according to the wavelength of each light source.

The parallel luminous flux 100b emitted from the light source device 100A is arranged in the illumination optical system 200A and is incident on the lens array element 3 composed of a plurality of element lenses. The lens array element 3 divides the parallel luminous flux 100b. The luminous flux divided by the lens array element 3 is focused by the condenser lens 4 at the focal position on the optical axis of the condenser lens 4. As a result, the luminance distribution of the parallel luminous flux 100b is made uniform. By arranging the light modulation element 300 at the focal position on the optical axis of the condenser lens 4, it is possible to form a luminous flux having a uniform luminance distribution on the light modulation element 300. The illumination optical system 200A may control the polarization direction of the parallel light flux 100b depending on the characteristics of the light modulation element 300, or may separate the parallel light flux 100b into light of three colors of RGB. The light modulation element 300 is composed of a transmissive or reflective liquid crystal panel, a digital micromirror device, or the like.

Although the illumination optical system 200A includes the lens array element 3 and the condenser lens 4 in this embodiment, it may include the optical element 5 having the functions of these elements shown in FIG. 9 of the first embodiment. .. The optical element 5 is provided with a lens array surface (first optical surface) that divides the light from the light source device 100A on the side of the light source device 100A, and the light divided by the lens array surface is provided on the side of the optical modulation element 300. A condenser lens surface (second optical surface) for condensing light is provided. By providing the optical element 5 having the functions of the two elements instead of providing the lens array element 3 and the condenser lens 4, the display device 700 can be further miniaturized.

FIG. 18 is a block diagram of a projector (image projection device) having a display device 700. The drive circuit 600 drives the light modulation element 300 according to an image signal input from the outside. The light modulation element 300 modulates the illumination light 200a according to the image signal to generate the image light 300a. The image light 300a is projected onto the projected surface 500 such as a screen via the projection optical system 400. The projection optical system 400 synthesizes the color-separated image light 300a and magnifies the image light 300a. As a result, the projected image as a color image is displayed.

Although the preferred embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various combinations, modifications and modifications can be made within the scope of the gist thereof.

1b, 1r, 1g Light source 2 Collimator lens 3 Lens array element (split element)
4 Condenser lens (condensing element)
10 Light source unit 20 Wavelength conversion element (optical characteristic conversion element)
100 light source device

Claims (7)

A light source unit including a plurality of light sources and a collimator lens for converting light fluxes from the plurality of light sources into parallel light flux, and a light source unit.
An optical characteristic conversion element that generates light having characteristics different from those of the light from the light source unit,
It has an optical system that irradiates the optical characteristic conversion element with light from the light source unit.
The optical system collects a dividing element that divides the light from the light source unit and a plurality of light divided by the dividing element, which are arranged in order from the side of the light source unit to the side of the optical characteristic conversion element. Including light source
When the focal length of the dividing element is f and the distance between the dividing element and the condensing element is L,
f / L ≧ 1.0
A light source device characterized by satisfying the conditional expression. When the width of the light from the light source unit is A and the width of the light incident on the dividing element is B,
0.90 ≤ B / A ≤ 1.10
The light source device according to claim 1, wherein the light source device satisfies the conditional expression. A light source unit including a plurality of light sources and a collimator lens for converting light fluxes from the plurality of light sources into parallel light flux, and a light source unit.
An optical characteristic conversion element that generates light having characteristics different from those of the light from the light source unit,
It has an optical system that irradiates the optical characteristic conversion element with light from the light source unit.
The optical system includes a first optical surface that divides the light from the light source unit on the side of the light source unit, and a plurality of light divided by the first optical surface on the side of the optical characteristic conversion element. A light source device comprising an optical element comprising a second optical surface for condensing light. When the width of the light from the light source unit is A and the width of the light incident on the first optical surface is B,
0.90 ≤ B / A ≤ 1.10
The light source device according to claim 3, wherein the conditional expression is satisfied. The light source device according to any one of claims 1 to 4, wherein the light characteristic conversion element has a conjugate relationship with an aerial cross section of light from the light source unit. The light source device according to any one of claims 1 to 5, wherein the number of light fluxes formed on the optical characteristic conversion element is more than 1. The light source device according to any one of claims 1 to 6.
An image projection device comprising a projection optical system for projecting an image on a projected surface using light from the light source device.

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