JP4893262B2 - Light source device and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device which has a simple constitution, is small-size and low-cost and can suppress coherence of emission light, and to provide an image display device provided with the light source device. <P>SOLUTION: The light source device includes: a separation part 12 arranged between a laser beam source 11 and a wavelength conversion element 13, reflecting the beams which pass through the wavelength element 13 in an optical path toward the laser beam source 11 and, thereby, are converted into a prescribed wavelength among beams reflected at an external cavity 14, guiding the beams to a position different from the laser beam source 11 and, at the same time, transmitting beams which are not converted into the prescribed wavelength to the laser beam source 11; and a reflection part 17 which reflects beams reflected at the separation part 12 toward an optical element 15, wherein beams which are transmitted by the external cavity 14 and travels through a first optical path A1 toward the optical element 15 and beams which are reflected at a reflection part 17 and travels through a second optical path A2 toward the optical element 15 intersect each other. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a light source device and an image display device including the same.

In recent projection type image display apparatuses, a discharge lamp such as an ultrahigh pressure mercury lamp is generally used as a light source. However, such a discharge lamp has problems such as a relatively short life, difficulty in instantaneous lighting, a narrow color reproduction range, and ultraviolet light emitted from the lamp may deteriorate the liquid crystal light bulb. Therefore, a projection type image display apparatus using a laser light source that emits monochromatic light instead of such a discharge lamp has been proposed. A laser light source as described in Patent Documents 1 to 3 can be used for such a projection type image display device. However, the laser light source does not have the above-described problems, but has a defect that it has coherence. Therefore, a laser illumination device in which the coherence of laser light is reduced has been proposed (see, for example, Patent Document 4).
The laser illumination device described in Patent Document 1 includes a laser light source, a split optical element that splits light emitted from the laser light source into a plurality of lights, a traveling direction of the split plurality of lights, and a plurality of split light elements. And a unit in which optical elements that change the optical path length of light are gathered. A plurality of lights emitted from the laser light source and divided by the split optical element are reflected by mirror surfaces inclined at 45 degrees in the unit. And the some light reflected by the mirror surface is inject | emitted as parallel light from a unit. At this time, the coherence of the laser light is reduced by making the optical path lengths of the plurality of lights different depending on the unit.
JP 59-128525 A Japanese Patent Laid-Open No. 7-86668 US Pat. No. 5,762,227 JP 2003-31872 A

However, in the laser illuminating device described in Patent Document 1, in order to suppress the coherence of a plurality of laser beams emitted from the laser light source and divided, the difference in optical path length of each light is set to an interference distance (coherence length). ) Or more. Here, the coherence length of the laser beam is several centimeters to several meters. That is, in the laser illumination device of Patent Document 1, an optical path difference of several centimeters to several meters or more is given to a plurality of lights. Therefore, the lighting device of Patent Document 1 is very large.
In addition, since the light reflected on the mirror surface provided in the unit is emitted from the unit as parallel light, the optical element disposed in the subsequent stage is also increased in size and the cost is increased.

  The present invention has been made in order to solve the above-described problems, and has a simple configuration, a small size, low cost, and a light source device and an image that can suppress the coherence of emitted light. An object is to provide a display device.

In order to achieve the above object, the present invention provides the following means.
The light source device of the present invention includes a laser light source, a wavelength conversion element that converts the wavelength of light emitted from the laser light source into a predetermined wavelength, and converts the light emitted from the wavelength conversion element into the predetermined wavelength. An external resonator that transmits the reflected light, reflects the light that has not been converted to the predetermined wavelength, and returns the light toward the laser light source, and the optical element uses the light emitted from the external resonator. A light source device that illuminates the light modulation device via the laser light source, the light source device disposed between the laser light source and the wavelength conversion element, and of the light reflected by the external resonator toward the laser light source In the optical path to go, the light converted to the predetermined wavelength by passing through the wavelength conversion element is reflected and guided to a position different from the laser light source, and the light that has not been converted to the predetermined wavelength A separation unit that transmits light toward the laser light source, and a reflection unit that reflects light reflected by the separation unit toward the optical element, and passes through the external resonator and travels toward the optical element. and light after wavelength conversion that travels on the optical path, wherein the light after wavelength conversion that travels the second optical path is reflected toward the optical element in the reflective portion, a different angle on the incident end surface of the optical element so as to intersect with each other It is incident on .

In the light source device according to the present invention, the light emitted from the laser light source passes through the wavelength conversion element. Of the light emitted from the wavelength conversion element, the light converted into light of a predetermined wavelength passes through the external resonator and enters the optical element. On the other hand, of the light emitted from the wavelength conversion element, the light that has not been converted to the predetermined wavelength is reflected by the external resonator, returned to the laser light source, and passes through the wavelength conversion element again. A part of the light is converted into a predetermined wavelength. In the present invention, in the light reflected by the external resonator, the light converted to a predetermined wavelength by passing through the wavelength conversion element in the optical path toward the laser light source is separated in the separation unit. Reflected and guided to a position different from the laser light source. Further, the light is then incident on the optical element by being reflected by the reflecting portion.
Furthermore, in the present invention, the optical axis of light traveling through the external resonator and traveling on the first optical path toward the optical element intersects with light traveling on the second optical path reflected by the reflecting portion and traveling toward the optical element. is doing. When the angle formed by the light traveling in the first optical path and the light traveling in the second optical path is θ, the interval between the interference fringes is wavelength / sin θ. Therefore, in the present invention, by setting the angle θ to a predetermined angle, it is possible to reduce the distance to an interval at which it is difficult to recognize the interval between the interference fringes. Further, the interference fringes can be made inconspicuous by changing the angle θ with time.

  Further, in the case of the conventional configuration, since the optical axis of the light traveling in the first optical path and the light traveling in the second optical path are parallel, it is necessary to use an optical element having an aperture through which a wide range of light can enter. However, in the present invention, since the optical axis of the light traveling in the first optical path and the optical axis of the light traveling in the second optical path form an angle, this is not necessary, and an optical element having a small aperture is used. be able to. Therefore, an inexpensive optical element can be used. That is, as compared with the conventional configuration in which the light emitted from the laser light source is branched into a plurality of beams, the optical path difference of each parallel light is set to the coherence length, and interference is reduced, the present invention has a simple configuration, and Therefore, it is possible to realize a light source device in which the entire apparatus is reduced in size and cost.

  In the light source device of the present invention, the angle θ between the light traveling in the first optical path and the light traveling in the second optical path is the light traveling in the first optical path and the light traveling in the second optical path. It is preferable that the interval between the interference fringes is set to be equal to or smaller than the pixel pitch of the light modulation device. By setting the angle θ to such a value, it is possible to reduce the distance to the distance at which it is difficult to recognize the distance between the interference fringes. Therefore, it is possible to irradiate the light modulation device with good illumination light.

  Moreover, the light source device of the present invention preferably includes a condensing element for folding at least one of the first optical path and the second optical path on at least one of the first optical path and the second optical path. .

  By providing such a condensing element, it is possible to condense light traveling in at least one of the first optical path and the second optical path onto the optical element, thereby improving the utilization efficiency of light traveling in each optical path. . Furthermore, since the distance from the external resonator and the optical element arranged at the rear stage of the reflecting portion can be shortened, the entire apparatus can be further reduced in size.

In the light source device of the present invention, a deflection element for bending at least one of the first optical path and the second optical path is provided on at least one of the first optical path and the second optical path. Is preferred.
With this configuration, the angle θ between the light traveling in the first optical path and the light traveling in the second optical path can be adjusted by the deflecting element, so that the human can recognize the interval between the interference fringes with a simpler configuration. It becomes possible to shorten to the extent that it is difficult to do.

  The deflecting element is preferably provided with a movable portion that temporally changes an angle formed by light traveling in the first optical path and light traveling in the second optical path.

  As described above, when the angle formed between the light traveling on the first optical path and the light traveling on the second optical path is changed with time by the movable portion, the interval between the interference fringes changes with time. The light emitted from the light is time-integrated by the afterimage effect, and the coherence is lowered. Therefore, in this case, the angle θ is not set so that the interval between the interference fringes between the light traveling in the first optical path and the light traveling in the second optical path is equal to or less than the pitch of the pixels of the light modulation device. However, it is possible to make it difficult for humans to recognize the interference fringes. As a result, it is possible to obtain illumination light in a good state regardless of the magnitude of the angle θ.

  Further, instead of providing a movable part in the deflecting element as described above, an angle θ may be changed with time by providing a movable part in the reflecting part, or the first optical path and the second optical path may be changed. At least one of the optical paths may be provided with an acousto-optic element that temporally changes the angle formed by the light traveling in the first optical path and the light traveling in the second optical path. In these cases, it is possible to obtain the same effect as when the movable element is provided in the deflection element.

  An image display device according to the present invention includes the light source device, a light modulation device that modulates light emitted from the light source device and then through an optical element according to an image signal, and the light modulation device. And a projection device that projects the modulated light.

  In the image display device according to the present invention, the light modulation device is illuminated by the light emitted from the light source device and then emitted through the optical element, and the image modulated by the light modulation device is transmitted through the projection device. Projected. At this time, since the light emitted from the light source device is light with suppressed interference fringes as described above, a good image with no noticeable interference fringes can be projected.

  In the image display device according to the aspect of the invention, the optical element is a uniformizing unit that uniformizes an illuminance distribution of light emitted from the light source device, and the light modulation device has an illuminance distribution by the uniformizing unit. It is preferably illuminated by uniformed light.

  By adopting such a uniformizing means, it becomes possible to project a better image.

  Embodiments of a light source device and an image display device according to the present invention will be described below with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

[First Embodiment]
Next, a first embodiment of the present invention will be described with reference to FIG.
The light source device 10 according to the present embodiment converts the wavelength of light emitted from the laser light source 11 and illuminates the liquid crystal light valve (light modulation device) 20 via a rod integrator (optical element: uniformizing means) 15. Is. Specifically, as shown in FIG. 1, the light source device 10 includes a laser light source 11 that emits monochromatic light, a wavelength conversion element 13 that converts the wavelength of laser light emitted from the laser light source 11, and a laser light source 11. Of the laser light emitted from the dichroic mirror (separating unit) 12 and the wavelength conversion element 13 disposed between the wavelength conversion element 13 and the wavelength conversion element 13, and transmits the other light. An external resonator 14 and a reflection mirror (reflection part) 17 that reflects the laser light reflected by the dichroic mirror 12 to the rod integrator 15 are provided.

  In the present embodiment, the wavelength of light emitted from the laser light source 11 is 920 nm for a blue laser light source device that emits blue laser light, 1060 nm for a green laser light source device that emits green laser light, and red. In the case of a red laser light source device that emits a laser beam of 1240 nm, the wavelength is 1240 nm. However, this wavelength is only an example. As the laser light source 11, for example, a single semiconductor laser or an array of a plurality of semiconductor lasers can be used.

A wavelength conversion element (SHG: Second Harmonic Generation) 13 is an optical element that converts incident light into a predetermined wavelength. In the case of the present embodiment, light emitted from the laser light source 11 and directed to the external resonator 14 is converted into light having substantially a half wavelength by passing through the wavelength conversion element 13. That is, in the case of a blue laser light source device, light (920 nm) emitted from the laser light source is converted into blue light of 460 nm by the wavelength conversion element. Similarly, in the case of a green laser light source device, the light emitted from the laser light source (1060 nm) is 530 nm green light, and in the case of the red laser light source device, the light emitted from the laser light source (1240 nm) is 620 nm red. Converted to light. However, the conversion efficiency of the wavelength conversion element 13 is about 40 to 50%. That is, not all of the light emitted from the laser light source 11 is converted into a laser beam having about half the wavelength. Therefore, the laser light emitted from the wavelength conversion element 13 is a mixture of laser light converted to a predetermined wavelength and laser light that has not been converted. The wavelength conversion efficiency by the wavelength conversion element 13 has non-linear characteristics. For example, the higher the intensity of the laser light incident on the wavelength conversion element, the higher the conversion efficiency. An optical path from the laser light source 11 to the external resonator 14 is defined as an outward path OW.
Here, a plate-shaped waveguide type is used as the wavelength conversion element 13. When such a waveguide type wavelength conversion element 13 is employed, the thickness of the wavelength conversion element 13 is thin, so that it is easy to create a periodic polarization inversion structure, to easily increase the wavelength conversion efficiency, and to reduce the manufacturing cost. it can.

The external resonator 14 transmits laser light converted to a predetermined wavelength (in the present embodiment, approximately half of the wavelength) out of the laser light emitted from the wavelength conversion element 13, and is not converted to the predetermined wavelength. The reflected laser beam is reflected back toward the wavelength conversion element 13. In the present embodiment, the external resonator 14 selectively reflects only light that has not been converted to a predetermined wavelength by the wavelength conversion element 13 out of the light emitted from the wavelength conversion element 13 with a high efficiency of about 99%. It has the characteristics to do. The light converted to a predetermined wavelength (920 nm for a blue laser light source, 530 nm for a green laser light source, 620 nm for a red laser light source) by the wavelength conversion element 13 passes through the external resonator 14.
The laser beam that has passed through the external resonator 14 enters the rod integrator 15 as it is. In this way, the optical path of the laser light that passes through the external resonator 14 and travels toward the rod integrator 15 is defined as a first optical path A1. In the present embodiment, the first optical path A1 indicates the central axis of the laser beam that passes through the external resonator 14 and travels toward the rod integrator 15.

On the other hand, light that has not been converted to a predetermined wavelength by the wavelength conversion element 13 (light having a wavelength of 920 nm for a blue laser light source, 530 nm for a green laser light source, and 620 nm for a red laser light source) 14 is reflected. Then, it passes through the wavelength conversion element 13 again and returns to the laser light source 11. In this way, the optical path from the external resonator 14 toward the laser light source 11 is defined as a return path HW. In a general laser light source device, such light is returned to the laser light source 11 as it is. However, there is also light that is converted into a predetermined wavelength by the wavelength conversion element 13 in the process of returning from the external resonator 14 toward the laser light source 11. The “predetermined wavelength” here is the same wavelength as the light transmitted through the external resonator 14 (that is, 460 nm for a blue laser light source device, 530 nm for a green laser light source device, and a red laser light source device). In the case of 620 nm). The dichroic mirror 12 prevents the laser light converted to a predetermined wavelength in the return path from returning to the laser light source 11 as it is. Specifically, the dichroic mirror 12 is disposed between the laser light source 11 and the wavelength conversion element 13, and of the laser light reflected by the external resonator 14, the optical path toward the laser light source 11 (return path HW). , The laser beam converted to the predetermined wavelength by passing through the wavelength conversion element 13 is reflected and guided to a position different from the laser light source 11, and the laser light that has not been converted to the predetermined wavelength is directed to the laser light source 11. It is made to pass through. The reflection surface of the dichroic mirror 12 is arranged so that light on the return path HW is incident at 45 degrees. Therefore, the laser beam converted to a predetermined wavelength in the return path HW is bent 90 degrees by the dichroic mirror 12.
The light that has not been converted to the predetermined wavelength in the return path HW passes through the dichroic mirror 12 and is returned to the laser light source 11 as it is. Thus, the light returned to the laser light source 11 is partially absorbed by the laser light source 11 and becomes heat, but most of the light is used as energy of the laser light source 11 or reflected by the laser light source 11. It is effectively used by being emitted from the laser light source again.
The reflection mirror 17 reflects the laser beam having a predetermined wavelength reflected by the dichroic mirror 12 toward the rod integrator 15. The reflection surface of the reflection mirror 17 is arranged so that the laser beam reflected by the dichroic mirror 12 is incident at an angle θ1. In this way, the optical path of the laser light reflected by the reflection mirror 17 and traveling toward the rod integrator 15 is defined as a second optical path A2. In the present embodiment, the second optical path A2 indicates the central axis of the laser beam that is reflected by the reflection mirror 17 and travels toward the rod integrator 15.
In FIG. 1, for ease of explanation, the positions of the forward path OW, the optical path A1, and the return path HW are shifted, but these are all located on the light source optical axis O indicated by a one-dot chain line. To do. Further, since the positions of the forward path OW, the optical path A1, and the return path HW are shifted, the optical path A1 and the optical path A2 reach different positions on the incident end face of the rod integrator 15, but these are incident on the rod integrator 15. It intersects at the position of the light source optical axis O on the end face. However, the optical path A1 and the optical path A2 do not necessarily need to intersect at the position of the light source optical axis O on the incident end face of the rod integrator 15, and may intersect with each other in the vicinity of the incident end face. The “near the incident end face” may be before or after the incident end face of the rod integrator (inside the rod integrator) as long as the rod integrator functions.

The laser light traveling on the first optical path A1 and the laser light traveling on the second optical path A2 intersect each other at an angle θ. The angle θ is set so that the interval between the interference fringes between the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 is equal to or smaller than the pitch of the pixels of the liquid crystal light valve 20. This is because it becomes difficult for humans to recognize interference fringes by setting such values. Here, P = λ / sin θ, where P is the interval between the interference fringes and λ is the wavelength emitted from the laser light source device 10. In this embodiment, the wavelength λ of the laser light extracted by the external resonator 14 and the dichroic mirror 12 is 530 nm for the green laser light source device, 460 nm for the blue laser light source device, and 620 nm for the red laser light source device. It is. The pixel pitch of the currently common liquid crystal light valve 20 is about 8.5 μm with a diagonal of 0.74 inches. Accordingly, in consideration of illuminating such a light valve, when the interference fringe spacing P is set to 8.51 μm or less, the angle θ is 3.10 in the case of a blue laser light source device as shown in FIG. In the case of a green laser light source device, it is set to 3.55 ° or less, and in the case of a red laser light source device, it is set to 4.18 ° or less.
This angle θ varies depending on the pixel pitch of the light valve and the wavelength of light, but the pixel pitch of the current general liquid crystal light valve and the wavelength of light (blue 440 to 460 nm, green 510 to 560 nm, red 620 to 630 nm) In consideration, it is preferably 15 degrees or less. Further, as the angle θ is decreased, the position where the optical path A1 and the optical path A2 intersect with each other is separated from the laser light source 11, and the distance between the light source device 10 and the optical element disposed on the downstream side of the optical path may be increased. There is sex. That is, when the light source device 10 is employed in the image display device, the image display device may be increased in size, and therefore the angle θ is preferably 0.5 degrees or more.

  The rod integrator 15 makes the in-plane illuminance distribution of the laser light substantially uniform at the emission end face. The laser light traveling on the first optical path A1 and the laser light traveling on the second optical path A2 are incident on the rod integrator 15 and reflected therein. Then, on the exit end face of the rod integrator 15, the illumination light is emitted as illumination light with a substantially uniform in-plane illuminance distribution. The liquid crystal light valve 20 is illuminated by the laser light having a uniform in-plane illuminance distribution.

In the light source device 10 according to the present embodiment, the angle θ formed by the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 is equal to the laser light traveling in the first optical path A1 and the second optical path A2. Since the interval between the interference fringes with the laser beam that travels is set to be equal to or less than the pixel pitch of the liquid crystal light valve 20, the interval between the interference fringes is difficult to be recognized by humans and is shortened to a certain extent. Can do.
Further, since the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 are at an angle, the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 By arranging the rod integrator 15 at a position where the crossing points intersect, the size of the incident end face 15a of the rod integrator 15 can be reduced. Therefore, it is possible to use the rod integrator 15 having a small cross-sectional area and being inexpensive, and to reduce the size and weight of the light source device.
That is, the light source device 10 of the present embodiment has a simple configuration, a small size, and low cost, and can suppress the coherence of emitted light.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIG. In each embodiment described below, portions having the same configuration as those of the light source device 10 according to the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
The light source device 30 according to the present embodiment is different from the first embodiment in that a condensing lens (condenser element) 31 is provided on the first optical path A1 and the second optical path A2.

  As shown in FIG. 3, the condenser lens 31 is disposed between the external resonator 14 in the first optical path A1 and the rod integrator 15 and between the reflecting mirror 17 and the rod integrator 15 in the second optical path A2. Has been. The condensing lens 31 condenses the laser light that passes through the external resonator 14 and travels through the first optical path A <b> 1 on the incident surface 15 a of the rod integrator 15. Further, the condenser lens 31 is reflected by the reflecting mirror 17 and bends the second optical path A2 in the direction of the light source optical axis O, and condenses the laser light traveling in the optical path A2 on the incident end face 15a of the rod integrator 15. . As in the first embodiment, the angle θ is such that the interval between the interference fringes between the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 is equal to or less than the pitch of the pixels of the liquid crystal light valve 20. Set to The angle θ1 is appropriately set in consideration of the refractive power of the condenser lens 31 and the angle θ.

  The light source device 30 according to the present embodiment has the same effects as the light source device 10 of the first embodiment. Furthermore, in the light source device 30 according to the present embodiment, the condensing lens 31 is provided so that the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 are respectively incident on the incident end face 15a of the rod integrator 15. It can be condensed. Thereby, it is possible to improve the utilization efficiency of the laser light traveling in the first optical path A1 and the second optical path A2. Furthermore, the condenser lens 31 can shorten the distance between the external resonator 14 and the rod integrator 15 and the distance between the reflection mirror 17 and the rod integrator 15. As a result, the rod integrator 15 can be disposed on the light source device 10 side as compared with the first embodiment, so that the overall size of the device can be further reduced.

[Modification 1 of the second embodiment]
In the embodiment of FIG. 3, one condenser lens 31 is arranged for the first optical path A1 and the second optical path A2, but the first condenser lens 31A1 is arranged in the first optical path A1, and the second A second condenser lens 31A2 may be disposed in the optical path A2. Such a modification will be described with reference to FIG. In each embodiment described below, parts having the same configuration as those of the light source devices 10 and 30 according to the first embodiment and the second embodiment described above are denoted by the same reference numerals and description thereof is omitted. To do.
The light source device 30A according to the present modification is different from the third embodiment in that separate condenser lenses (condenser elements) 31A1 and 31A2 are provided on the first optical path A1 and the second optical path A2. In the embodiment of FIG. 3, the optical path A1 coincides with the light source optical axis O, and the optical path A2 is tilted with respect to the light source optical axis O to form the angle θ. The angle θ is formed by inclining the light source optical axis O so that the optical path A2 coincides with the light source optical axis O. In the light source device 30A according to this modification, the axis of the laser light source 11 (referred to as the central axis of light emitted from the laser light source 11) OL and the light source optical axis O are shifted in a parallel state. Yes. The axis OL of the laser light source 11 coincides with the central axis of the light emitted from the laser light source 11, and the light source optical axis O coincides with the center of the rod integrator 15. However, in FIG. 4, for easy understanding, the positions of the forward path OW, the portion of the optical path A1 before entering the lens 31A1, and the position of the return path HW are shifted. These are all located on the axis OL of the laser light source indicated by the one-dot chain line. Similarly, the optical path A2 is located on the light source optical axis O. The center of the image forming area 20 of the liquid crystal light valve 20 is arranged so as to substantially coincide with the light source optical axis O.
The laser light that has passed through the external resonator 14 is emitted along the axis OL of the laser light source 11, and enters the condenser lens 31A1. The first condenser lens 31A1 disposed in the optical path A1 bends the laser light (optical path A1) emitted along the axis OL of the laser light source 11 in the direction of the light source optical axis O and travels along the optical path A1. The light is condensed on the incident end face 15 a of the rod integrator 15.
On the other hand, the laser beam reflected by the external resonator 14 and converted into a predetermined wavelength by the return path HW is bent 90 degrees by the mirror 12 and enters the mirror 17. The reflection surface of the mirror 17 is arranged so that the laser beam reflected by the dichroic mirror 12 is incident at an angle θ1. In this modification, the angle θ1 is set to 45 degrees. Therefore, the light incident on the mirror 17 is bent 90 degrees and travels toward the rod integrator 15 along the light source optical axis O. The second condenser lens 31 arranged in the optical path A2 condenses the laser light traveling in the optical path A2 on the incident end face 15a of the rod integrator 15.
In FIG. 4, since the portion of the optical path A1 before entering the lens 31A1 is shifted from the axis OL and the optical path A2 is shifted from the light source optical axis O, the optical path A1 and the optical path A2 are incident end faces of the rod integrator 15. Although they have reached different positions above, they intersect at the position of the light source optical axis O on the incident end face of the rod integrator 15. However, the optical path A1 and the optical path A2 do not necessarily need to intersect at the position of the light source optical axis O on the incident end face of the rod integrator 15, and may intersect with each other in the vicinity of the incident end face. The “near the incident end face” may be before or after the incident end face of the rod integrator (inside the rod integrator) as long as the rod integrator functions.
Thus, by providing separate condensing lenses 31A1 and 31A2 in the first optical path A1 and the second optical path A2, the incident end face 15a of the rod integrator 15 for the laser light traveling in the first optical path A1 or the second optical path A2 is provided. It is possible to individually adjust the incident angle with respect to. Therefore, the degree of freedom in designing the optical system is increased.
In this modification, the optical path A2 is aligned with the light source optical axis O, and the angle θ is formed by tilting only the optical path A1 with respect to the light source optical axis O. However, both of the optical paths A2 and A2 are light source light. A configuration in which it is inclined with respect to the axis O is also possible. At this time, the condensing lens 31A1 has a function of bending the optical path A1 and a function of condensing the laser light traveling along the optical path A1. On the other hand, the optical lens 31A2 can have both the function of bending the optical path A2 and the function of condensing the laser light, as in the case of the condensing lens 31A1, but it has only the condensing function, and the optical path The function of bending can also be realized by adjusting the angle θ1 of the mirror 17.
In this modification, the condensing lenses 31A1 and 31A2 are provided in both the first optical path A1 and the second optical path A2, but the condensing lens is provided in only one of the optical paths A1 and A2. Only the laser beam traveling in the optical path may be condensed. At this time, the condensing lens provided in the optical path A1 or A2 does not have the function of bending the optical path, but only the condensing function, and the function of bending the optical path can be realized by adjusting the angle θ1 of the mirror 17. Is possible.

[Modification 2 of the second embodiment]
In the embodiment of FIG. 3, by making the angle θ1 smaller than 45 degrees, the part of the optical path A2 up to the reflecting mirror 17 and the condenser lens 31 is also non-parallel to the light source optical axis O. The angle θ1 may be set to 45 degrees. In this case, as shown in FIG. 5, the part of the optical path A2 from the reflecting mirror 17 to the condenser lens 32 is parallel to the light source optical axis O, and only the part from the condenser lens 32 to the rod integrator 15 is present. It becomes non-parallel to the light source optical axis O. The configuration of FIG. 5 is particularly advantageous in that the aberration of the condenser lens 32 can be actively used. That is, when there is an aberration in the condenser lens 32, the coherence is weakened by the aberration in addition to the original power of the condenser lens 32 (the force that bends the optical path A2). Is possible.

[Third Embodiment]
Next, a third embodiment according to the present invention will be described with reference to FIG.
The light source device 40 according to the present embodiment is different from the first embodiment in that a prism (deflection element) 41 is provided on the second optical path A2.
The reflection mirror 17 is arranged so that the incident angle θ1 of the laser beam is 45 degrees, and the incident laser beam is parallel to the laser beam traveling in the first optical path A1, that is, parallel to the light source optical axis O. To reflect in any direction.
The prism 41 has a wedge shape, and bends the laser light (optical path A2) reflected by the reflection mirror 17 so as to be directed toward the center of the incident surface 15a of the rod integrator 15. Depending on the shape and arrangement of the prism 41, it is possible to adjust the angle θ between the light traveling on the first optical path A1 and the light traveling on the second optical path A2. As in the first embodiment, the angle θ is such that the interval between the interference fringes between the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 is equal to or less than the pitch of the pixels of the liquid crystal light valve 20. Set to

The light source device 40 according to the present embodiment has the same effects as the light source device 10 of the first embodiment. Furthermore, in the light source device 40 according to the present embodiment, the prism 41 can adjust the angle θ between the laser light traveling on the first optical path A1 and the laser light traveling on the second optical path A2, and thus is simpler. With this configuration, it is possible to shorten the interval between the interference fringes to a certain extent that is difficult for humans to recognize.
The prism 41 can also be integrated with the reflection mirror 17. Such integration makes it possible to reduce the size of the apparatus.
It is also possible to arrange the prism 41 not in the second optical path A2 but in the first optical path A1. In this case, the angle θ can be formed by tilting the optical path A1 with respect to the light source optical axis O. At this time, the optical path A2 may be aligned with the light source optical axis O by setting the angle θ1 to 45 degrees, but the angle θ1 is made smaller than 45 degrees and tilted with respect to the light source optical axis O. It is also possible. Further, by arranging the prism 41 in both the first optical path A1 and the second optical path A2, a configuration in which both the optical paths A2 and A2 are inclined with respect to the light source optical axis O is possible.

[Fourth Embodiment]
Next, a fourth embodiment according to the present invention will be described.
The light source device 50 according to the present embodiment is different from the first embodiment in that an electrostatic actuator (movable part) 52 is provided on the reflection mirror 51 as shown in FIG.
As shown in FIG. 8A, the electrostatic actuator 52 is provided at the central portion of the reflection mirror 51, and also includes a GND electrode 52a formed of a bending spring and a first electrode 52b provided with the GND electrode 52a interposed therebetween. And a second electrode 52c. As shown in FIG. 8B, an alternating voltage is applied to the first electrode 52b and the second electrode 52c so that a potential difference is generated between the first electrode 52b and the second electrode 52c. Thereby, the reflection mirror 51 rotates around the rotation axis M1. Then, as shown by an arrow P in FIG. 8, the tilt of the laser beam reflected by the reflecting mirror 51, that is, the tilt of the optical path A2 can be temporally changed.

  In the light source device 50 according to the present embodiment, the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 are obtained by temporally changing the inclination of the optical path A2 by the electrostatic actuator 52 in this way. Since the angle θ formed by is changed with time, the interval P between the interference fringes changes with time. Therefore, the light emitted from the rod integrator 15 is time-integrated by the afterimage effect, and the coherence is lowered. Therefore, in this case, the angle θ is set so that the interval between the interference fringes between the laser light traveling in the first optical path A1 and the laser light traveling in the second optical path A2 is equal to or less than the pitch of the pixels of the liquid crystal light valve 20. Even without setting, it is possible to make it difficult for humans to recognize interference fringes. That is, the light source device 50 of the present embodiment has a simple configuration, a small size, and a low cost, and suppresses the coherence of emitted light regardless of the size of the angle θ. It is possible.

  In the present embodiment, the electrostatic actuator 52 is used as the movable portion. However, the present invention is not limited to this, and an electromagnetic actuator 55 as shown in FIG. 9A may be used. The electromagnetic actuator 55 includes a GND electrode 55a provided at the center of the reflection mirror 56, an S-pole magnet 55b provided on one end face 56a of the reflection mirror 56, and an N pole provided on the other end face 56b. Magnet 55c and a pair of electromagnetic coils 55d and 55e provided with a GND electrode 55a therebetween. Further, an AC voltage as shown in FIG. 9B is applied to the electromagnetic coils 55d and 55e. Accordingly, since the reflection mirror 56 rotates about the rotation axis M2, the angle θ formed by the laser light traveling on the first optical path A1 and the laser light traveling on the second optical path A2 is changed temporally. Is possible.

Moreover, you may use the piezoelectric actuator 60 as a movable part. As shown in FIG. 10A, the piezoelectric actuator 60 includes a GND electrode 60a, a first piezoelectric element 60b provided on one end 61a side of the reflection mirror 61 between the GND electrode 60a and the reflection mirror 61, and a reflection mirror. 61, the second piezoelectric element 60c provided on the other end 61b side. An alternating voltage as shown in FIG. 10B is applied to the first piezoelectric element 60b and the second piezoelectric element 60c. Accordingly, since the reflection mirror 61 rotates about the rotation axis M3, the angle θ formed by the laser light traveling on the first optical path A1 and the laser light traveling on the second optical path A2 is changed with time. Is possible.
In the present embodiment, the reflection mirror 51 corresponding to the reflection mirror 17 of the light source device of the first embodiment is rotated. However, the light source device of the second and third embodiments (including modifications) is rotated. The reflection mirror 17 may be provided with a movable part as described above.

[Modification 1 of Fourth Embodiment]
In the fourth embodiment, the reflection mirror 51 is rotated by the electrostatic actuator 52, the electromagnetic actuator 55, and the piezoelectric actuator 60. Instead, the prism 41 of the third embodiment (including the modified example) is rotated. You may make it let it. Also in this case, the electrostatic actuator 52, the electromagnetic actuator 55, and the piezoelectric actuator 60 as described above may be provided at positions that do not hinder the incidence of laser light on the prism 41 and the emission of laser light from the prism 41.
[Modification 2 of the fourth embodiment]
Furthermore, instead of rotating the reflecting mirrors 17 and 51 and the prism 41, an AOM (acousto-optic element) 46 as shown in FIG. 11 may be used. In this configuration, the angle of the laser light emitted from the AOM 46 is adjusted by the frequency supplied to the AOM 46. That is, the AOM 46 can function as a movable part. In this case, the same effect as that of the fourth embodiment can be obtained by changing the frequency of the AC voltage applied to the AOM 46 at a frequency higher than the frequency of flicker that can be detected by humans, for example, 30 Hz or more, preferably 60 Hz or more. Can be obtained. In this modification, since the frequency supplied to the AOM 46 may be changed according to the position of the rod integrator 15, the degree of freedom of arrangement of the rod integrator 15 is improved. The incident angle θ1 of the laser beam to the reflection mirror 17 is not limited to 45 degrees, and may be smaller than that. In this modification, the AOM 46 is arranged in the second optical path A2, and the angle θ is changed temporally by changing the inclination of the optical path A2 with time. However, the AOM 46 is arranged in the first optical path. The angle θ may be changed with time by changing the inclination of the optical path A1 with time. Moreover, you may make it provide AOM46 in both 1st optical path A1 and 2nd optical path A2. Further, FIG. 11 illustrates a configuration in which the condensing lens 31 of the second embodiment (including the modification) and the AOM 46 are provided instead of the prism 41 of the third embodiment. In addition to the prism 41 or the like, an AOM 46 may be provided.

[Fifth Embodiment]
Next, a fifth embodiment according to the present invention will be described with reference to FIG.
In the present embodiment, a projector (image display device) 500 including the light source device 10 of the first embodiment will be described.

FIG. 12 is an explanatory diagram of a projector 500 including the light source device of the above embodiment.
The projector 500 includes light source devices 10R, 10G, and 10B, liquid crystal light valves 522, 523, and 524, a cross dichroic prism 525, and a projection lens (projection device) 526.

The projector 500 of FIG. 12 uses the light source device of the first embodiment as the green light source device 10G and the blue light source device 10B. The red light source device 10R includes only a laser light source, and emits laser light having a wavelength of 620 nm emitted from the laser light source without performing wavelength conversion. Note that the configurations and the like of the green light source device 10G and the blue light source device 10B have been described in the first embodiment, and thus detailed description thereof is omitted.
Further, rod integrators (optical elements: equalizing means) 15R, 15G, and 15B are provided in the subsequent stage (downstream side of the optical path) of the respective light source devices 10R, 10G, and 10B. Since these are the same as the rod integrator 15 described in the first embodiment, a detailed description thereof will be omitted.

  The light beam from the red light source device 10R is made uniform by the rod integrator 15R, then passes through the transmission lens 535R, is reflected by the reflection mirror 517, and enters the red light liquid crystal light valve 20R. Further, the light flux from the green light source device 10G is made uniform by the rod integrator 15G, then passes through the transfer lens 535G and enters the green light liquid crystal light valve 20G. The light beam from the blue light source device 10B is made uniform by the rod integrator 15B, then passes through the transmission lens 535B, is reflected by the reflection mirror 516, and enters the blue light liquid crystal light valve 20B. The transmission lenses 535R, G, and B are all for transmitting the image of the exit end face of the rod integrator 15R, G, and B to the image forming area of the liquid crystal light valve. In the present embodiment, the liquid crystal light valve is uniformly illuminated by the action of the rod integrators 15R, G, B and the transfer lenses 535R, G, B. The shape of the exit end face of the rod integrator 15R, G, B is the same as the image forming area of the liquid crystal light valve 20R, G, B, and the rod integrator 15R, G, B is the liquid crystal light valve 20R, G, B. The lenses 535R, G, and B can be omitted when they are arranged close to each other. In FIG. 12, the transmission lenses 535R, G, and B are illustrated as lenses having substantially the same shape, but the functions of the transmission lenses 535R, G, and B are the light sources 10R, G, and B and the liquid crystal light valves 20R, G. , B are optimized in accordance with the distance, etc., and therefore do not necessarily have the same shape.

  Polarizers (not shown) are arranged on the incident side and the emission side of each liquid crystal light valve 20R, G, B. Of the light beams from the light source devices 10R, 10G, and 10B, only linearly polarized light in a predetermined direction passes through the incident side polarizing plate and enters each liquid crystal light valve. Since the laser light is basically light having a uniform polarization state (linearly polarized light), the incident-side polarizing plate can be omitted. However, there is a possibility that the polarization state is somewhat disturbed when passing through the optical elements such as the rod integrators 15R, G, B and the reflection mirrors 516, 517 before reaching the liquid crystal light valves 20R, G, B from the light source. There is. Therefore, it is possible to improve the contrast of the image by providing the incident side polarizing plate and aligning the polarization state. Also, a polarization conversion means (not shown) is provided in front of the incident side polarizing plate or instead of the incident side polarizing plate so that the light incident on the liquid crystal light valves 20R, 20G, 20B is aligned with linearly polarized light. Also good. In this case, when the polarization conversion means is provided in front of the incident side polarizing plate, it is possible to reduce light loss due to light being absorbed or reflected by the incident side polarizing plate. Therefore, the light use efficiency can be improved. When a polarization conversion means is provided instead of the incident side polarizing plate, the contrast of the image can be improved as in the case of the incident side polarizing plate.

  The three color lights modulated by the liquid crystal light valves 20R, 20G, and 20B are incident on the cross dichroic prism 525. This prism is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the projection screen 527 by the projection lens 526 which is a projection optical system, and an enlarged image is displayed.

In the projector 500 of the present embodiment described above, the green light source device 10G and the blue light source device 10B have a simple configuration, a small size, and low cost, and can suppress the coherence of emitted light. The light source device of the first embodiment is used. Therefore, the projector 500 according to the present embodiment has a simple configuration, is small in size, and low in cost, and can display a good image with no noticeable interference fringes on the projection screen 527.
In the projector according to this embodiment, the green and blue light source devices 10G and B using the light source device 10 according to the first embodiment have been described. However, the red light source device 10R is also used as the light source device according to the first embodiment. 10 can be employed. Moreover, it is also possible to use the light source device of 2nd-4th embodiment (a modification is included) about light source device 10R, G, B. FIG.
Moreover, the light source device of 1st-4th embodiment (a modification is included) should just be applied to at least one among the light source devices 10R, G, and B. Furthermore, it is also possible to employ light source devices of different embodiments for each of the light source devices 10R, 10G, and B.

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 each of the above-described embodiments, the rod integrator 15 or the like is used as the uniformizing means. Moreover, the optical element disposed between the light source device 10 and the like and the light modulation device 20 and the like is not limited to the uniformizing means, and may be another optical element such as a lens or a prism. In the above embodiment, the number of optical elements arranged between the light source device 10 and the like and the light modulation device 20 and the like is one (only uniformizing means), but two or more optical elements are arranged. You may make it do.
In the above-described embodiment, an example in which a transmissive liquid crystal light valve is used as the light modulation device has been described. However, the present invention can also be applied to a modulation device other than the liquid crystal light valve. Further, although there are a transmission type and a reflection type in the light modulation device, the present invention is applicable to any type.
Furthermore, in the fifth embodiment, an example of a projector using three light modulation devices has been described, but the present invention is also applicable to a projector using one, two, or four or more light modulation devices. Can do. As a projector, there are a front type that projects an image from the direction of observing the projection surface and a rear type that projects an image from the side opposite to the direction of observing the projection surface. It is also applicable to types.
In the fifth embodiment, the projector is described as an example of the image display device. However, the light source device of the present invention can be applied to an image display device other than the projector.

It is a top view which shows the light source device which concerns on 1st Embodiment of this invention. It is a graph book which shows the relationship between the angle (theta) which 1st optical path A1 and 2nd optical path A2 make, and the space | interval P of an interference fringe. It is a top view which shows the light source device which concerns on 2nd Embodiment of this invention. It is a top view which shows the light source device which concerns on the modification 1 of 2nd Embodiment of this invention. It is a top view which shows the modification of the light source device which concerns on the modification 2 of 2nd Embodiment of this invention. It is a top view which shows the light source device which concerns on 3rd Embodiment of this invention. It is a top view which shows the modification of the light source device which concerns on 3rd Embodiment of this invention. It is a top view which shows the light source device which concerns on 4th Embodiment of this invention. It is a top view which shows the movable part of the light source device of FIG. It is a top view which shows the modification of the movable part of the light source device of FIG. It is a top view which shows the modification of the movable part of the light source device of FIG. It is a top view which shows the image display apparatus provided with the light source device of this invention.

Explanation of symbols

  10, 10R, 10G, 10B, 30, 35, 40, 45 ... light source device, 11 ... laser light source, 12 ... dichroic mirror (separation unit), 13 ... wavelength conversion element, 14 ... external resonator, 15, 15R, 15G , 15B ... Rod integrator (optical element: uniformizing means), 17 ... Reflection mirror (reflection part), 20, 20R, 20G, 20B ... Liquid crystal light valve (light modulation device), 31 ... Condensing lens (condensing element) , 41 ... Prism (deflection element), 500 ... Projector (image display device), 526 ... Projection lens (projection device)

Claims (9)

A laser light source;
A wavelength conversion element that converts the wavelength of light emitted from the laser light source into a predetermined wavelength;
An external resonator that transmits light that has been converted to the predetermined wavelength out of light emitted from the wavelength conversion element, reflects light that has not been converted to the predetermined wavelength, and returns the light toward the laser light source; With
A light source device that illuminates a light modulation device via an optical element with light emitted from the external resonator,
The light source is disposed between the laser light source and the wavelength conversion element, and passes through the wavelength conversion element in an optical path toward the laser light source among the light reflected by the external resonator. A separation unit that reflects the light converted into the wavelength of the laser and guides the light to a position different from the laser light source, and transmits the light that has not been converted into the predetermined wavelength toward the laser light source;
A reflection unit that reflects the light reflected by the separation unit toward the optical element;
Wherein the light after wavelength conversion traveling the first optical path passes through the external resonator toward the optical element, the light after wavelength conversion that travels the second optical path is reflected toward the optical element in the reflective portion The light source device is incident on the incident end face of the optical element at different angles so as to cross each other.   The angle between the light traveling on the first optical path and the light traveling on the second optical path is such that the interval between interference fringes between the light traveling on the first optical path and the light traveling on the second optical path is the light. The light source device according to claim 1, wherein the light source device is set to have an angle that is equal to or smaller than a pixel pitch of the modulation device.   3. The condensing element for bending at least one of the first optical path and the second optical path is provided on at least one of the first optical path and the second optical path. 4. The light source device according to 1.   The deflection element for bending at least one of the first optical path and the second optical path is provided on at least one of the first optical path and the second optical path. Item 3. The light source device according to Item 2.   5. The movable element that changes temporally an angle formed by the light traveling in the first optical path and the light traveling in the second optical path is provided in the deflection element. Light source device.   The movable part which changes temporally the angle which the light which follows the said 1st optical path and the light which follows the said 2nd optical path makes in the said reflection part is provided. Item 5. The light source device according to any one of Items 4.   At least one of the first optical path and the second optical path is provided with an acousto-optic element that temporally changes an angle formed by light traveling through the first optical path and light traveling through the second optical path. The light source device according to claim 1, wherein the light source device is a light source device. The light source device according to any one of claims 1 to 7,
A light modulation device that modulates light emitted from the light source device through the optical element according to an image signal;
An image display device comprising: a projection device that projects light modulated by the light modulation device.   The optical element is a uniformizing unit that uniformizes an illuminance distribution of light emitted from the light source device, and the light modulator is illuminated by light whose illuminance distribution is uniformized by the uniformizing unit. The image display device according to claim 8.

Images