JP2010156841A - Illumination device and projection type display device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device reducing a speckle without reducing the advantage of a laser light source, and to provide a projection type display device having it. <P>SOLUTION: An optical path of an illumination optical system receiving illumination light emitted from the laser light source 1 is disposed with a speckle removal means 8 including: a polarization direction conversion means 6 changing a polarization direction of the illumination light with time; and an optical path change means 7 changing an optical path of the illumination light incident through the polarization direction conversion means 6 according to the polarization direction. Thereby, the optical path and the polarization direction of the illumination light emitted from the speckle removal means 8 can be changed with time, so that a plurality of different speckle patterns can be formed on a screen. As a result, the speckle patterns are averaged to reduce the speckle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lighting device technology, and more particularly to a lighting device technology using a laser light source.

  Conventionally, as a light source of a projection display device such as a projector, an ultrahigh pressure mercury lamp or a light emitting diode (LED) light source has been widely used. On the other hand, these light sources are limited in size reduction and image color reproducibility in the case of an ultra-high pressure mercury lamp, and in the case of an LED light source, a light image with poor luminous efficiency and Etendue is displayed. Issues that are difficult to do are pointed out. On the other hand, when a laser light source is used, it is possible to improve the downsizing of the device and the color reproducibility and brightness of the image, which are problems with the above light source. For this reason, in recent years, the use of a laser light source as a light source of a projection display device has been proposed. When a laser light source is used as a light source of a projection display device, so-called speckles may be generated in a display image due to high coherence (coherence) of laser light. When speckles, which are irregular bright and dark dot patterns with high contrast, occur, the image quality of the displayed image is significantly impaired. Therefore, many techniques for reducing speckles have been proposed.

  FIG. 9 is a schematic diagram of a bundle fiber disclosed in Patent Document 1. As illustrated in FIG. 9, in Patent Document 1, light is incident on a bundle fiber 700 that includes a plurality of optical fibers (optical fibers 700 a, 700 b, 700 c, and 700 d) that are different from each other in coherent length, thereby allowing the bundle fiber to enter. A technique for reducing the coherence of light emitted from 700 and suppressing speckles is disclosed.

  FIG. 10 is a diagram for explaining the configuration of the projector device disclosed in Patent Document 2. In FIG. As illustrated in FIG. 10, in Patent Document 2, laser light emitted from a laser light source 702 illuminates a GLV (grating light valve) 707 via a half-wave retardation plate 704 and an illumination lens 706. The structure to perform is disclosed. At that time, the half-wave retardation plate 704 is rotated in a plane perpendicular to the optical axis of the laser beam by a motor 703 that rotates at a predetermined speed based on the electric power from the drive unit 705. For this reason, the polarization direction of the laser light changes with time, thereby suppressing speckles.

  FIG. 11 is a diagram showing an optical configuration of the birefringent device disclosed in Patent Document 3. As shown in FIG. As illustrated in FIG. 11, in Patent Document 3, the light separated by the birefringent plate 708 composed of the birefringent medium 709 and the birefringent medium 710 overlaps in a slightly shifted state on the screen, thereby causing speckle. Suppressed techniques are disclosed.

  FIG. 12 is a schematic configuration diagram of a scanning display device disclosed in Patent Document 4. As illustrated in FIG. 12, Patent Document 4 also discloses a technique in which speckle is suppressed by illuminating the screen 713 with light emitted from a laser light source 711 through a birefringent plate 712.

FIG. 13 is a block diagram showing a schematic configuration of the projection display device disclosed in Patent Document 5. Patent Document 5 is not a technique for reducing speckles, but discloses a technique using a birefringence phenomenon as in Patent Documents 3 and 4. As illustrated in FIG. 13, the light emitted from the light source 714 is modulated by the display liquid crystal panel 715, the combination of the polarization direction control liquid crystal panel 716 and the crystal plate 717, and the polarization direction control liquid crystal panel 718 and the crystal. A technique is disclosed in which a birefringence phenomenon is caused in each of the combinations of the plates 719, thereby shifting the display position of the image to increase the definition of the image.
Japanese Patent Laid-Open No. 11-223795 JP 2006-91471 A US 20080049284 Specification JP 2006-284749 A Japanese Patent No. 2813041

  However, when the technique disclosed in Patent Document 1 is used, a difference in length equal to or greater than the coherence length is required, so that the optical fiber itself becomes longer, and a space 701 for gathering the optical fibers is required. For this reason, there is a problem that the size of the apparatus is increased at the expense of the downsizing of the apparatus, which is one of the merits of the laser light source.

  When the technique disclosed in Patent Document 2 is used, a rotation mechanism for rotating the half-wave retardation plate 704 is required to change the polarization state. For this reason, in addition to the enlargement of an apparatus, the subject that a manufacturing cost raises occurs.

  In addition, when the techniques disclosed in Patent Document 3 and Patent Document 4 are used, the polarization direction of the laser light and the optical axis are inclined, so that the polarization component perpendicular to the optical axis of the laser light is parallel to the optical axis. A polarized component is always emitted. That is, a plurality of speckle patterns are formed by emitting a plurality of laser beams, but the temporal speckle pattern does not change. Also, depending on the relationship between the direction of the optical axis and the polarization direction, the balance between the polarization component perpendicular to the optical axis and the polarization component parallel to the optical axis may be biased, thereby reducing the effect of averaging and reducing the speckle pattern. May end up.

  Further, the technique disclosed in Patent Document 5 has a configuration in which liquid crystal panels (polarization direction control liquid crystal panel 716 and polarization direction control liquid crystal panel 718) are arranged on the projection optical path, so that the response performance of the liquid crystal panel is sufficient. Otherwise, the quality of the projected image will deteriorate. For this reason, even when it is used for the purpose of speckle reduction, there is a problem that it is necessary to drive the liquid crystal panel faster than necessary in consideration of the influence on the image quality.

  In view of the above circumstances, an object of the present invention is to provide an illumination device that reduces speckles without impairing the merit of a laser light source, and a projection display device including the illumination device.

  A first aspect of the present invention includes a laser light source that emits illumination light, an illumination optical system that the illumination light is incident on, and speckle removal means that is disposed in the optical path of the illumination optical system. The means includes an illuminating device including a polarization direction converting unit that switches a polarization direction of the illumination light with time, and an optical path changing unit that changes an optical path of the illumination light incident through the polarization direction converting unit according to the polarization direction. provide.

  According to a second aspect of the present invention, there is provided the illumination apparatus according to the first aspect, further including a polarizing plate that aligns the polarization direction of the illumination light in the optical path between the laser light source and the polarization direction conversion unit. provide.

According to a third aspect of the present invention, in the illumination device according to the first aspect or the second aspect, the polarization direction conversion unit includes a first polarization direction conversion unit and a second polarization direction conversion unit. The optical path changing means includes a first optical path changing means and a second optical path changing means, and the speckle removing means includes, in order from the light source side, a first polarization direction converting means and a first optical path. Provided is an illuminating device including a changing unit, a second polarization direction converting unit, and a second optical path changing unit.

According to a fourth aspect of the present invention, there is provided the illuminating device according to the third aspect, wherein the second optical path changing unit changes the optical path of the illumination light in a direction different from the first optical path changing unit. .
According to a fifth aspect of the present invention, in the illumination device according to any one of the first to fourth aspects, the polarization direction conversion unit is a liquid crystal cell whose liquid crystal state is changed over time. I will provide a.

  According to a sixth aspect of the present invention, in the illumination device according to any one of the first to fourth aspects, the optical path changing unit includes an optical path of illumination light whose optical path is changed by the optical path changing unit, and the optical path thereof. Provided is an illuminating device that variably changes a distance between optical paths of illumination light whose optical path is not changed by a changing unit.

According to a seventh aspect of the present invention, there is provided the illumination device according to any one of the first to fourth aspects, wherein the optical path changing unit vibrates the optical path changing unit.
According to an eighth aspect of the present invention, there is provided the illumination device according to any one of the first to fourth aspects, wherein the polarization direction conversion means switches the polarization direction of the illumination light at a period of 60 Hz or more. To do.

  According to a ninth aspect of the present invention, there is provided the illumination device according to any one of the first to fourth aspects, wherein the polarization direction changing unit and the optical path changing unit are formed as one unit. To do.

  According to a tenth aspect of the present invention, there is provided the illumination device according to any one of the first to ninth aspects, a spatial light modulator that modulates light emitted from the illumination device, and modulation by the spatial light modulator. And a projection optical system that projects the emitted light.

  According to an eleventh aspect of the present invention, in the projection display device according to the tenth aspect, the spatial light modulator includes a plurality of pixel units, and the illumination device is not more than half the pitch of the pixel units over time. Provided is a projection display device that illuminates a spatial light modulator by shifting an illumination range.

  ADVANTAGE OF THE INVENTION According to this invention, the illumination apparatus which reduces a speckle, and a projection type display apparatus provided with the same can be provided, without impairing the merit of a laser light source.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<First Embodiment>
FIG. 1 is a diagram illustrating an example of a configuration of a projection display device according to the present embodiment.

  The projection display device 100 according to the present embodiment includes an illumination device 100a, a spatial light modulator 12 that modulates light emitted from the illumination device 100a, and a projection optical system that projects light modulated by the spatial light modulator. 13. The illumination device 100a includes a laser light source 1 for each color (green (G) laser light source 1a, blue (B) laser light source 1b, red (R) laser light source 1c), a lens 2 provided for each color laser light source 1 and It includes a dichroic mirror 3, a rod integrator 4, a lens 5, a speckle removal unit 8 (speckle removal means), a control unit 9 that controls the speckle removal unit 8, a lens 10, and a TIR prism 11. It is configured.

Further, the speckle removing unit 8 (speckle removing means) includes a liquid crystal cell 6 and a birefringent plate 7, and includes a lens 2, a dichroic mirror 3, a rod integrator 4, a lens 5, a lens 10, and a TIR prism. 11 in the optical path of the illumination optical system. The liquid crystal cell 6 is controlled by the control unit 9 so that the liquid crystal state changes over time.

Hereinafter, an outline of the operation of the projection display apparatus 100 will be described.
First, laser light (illumination light) emitted from the laser light sources 1 of the respective colors is combined via the lens 2 and the dichroic mirror 3 and enters the rod integrator 4 from an incident end conjugate with the laser light source 1. The light incident on the rod integrator 4 is emitted from the exit end in a state where the intensity is uniform. Laser light (illumination light) emitted from the rod integrator 4 enters the speckle removal unit 8 via the lens 5. As will be described in detail later, the speckle removal unit 8 changes the polarization direction and optical path of laser light (illumination light) over time due to the action of the liquid crystal cell 6 and the birefringent plate 7. As a result, the light emitted from the speckle removal unit 8 enters the spatial light modulator 12 via the lens 10 and the TIR prism 11 in a state that changes with time. The spatial light modulator 12 has a plurality of pixel units, and reflects only light necessary for each pixel unit in the projection direction according to image information under the control of a spatial light modulator control unit (not shown). Modulates laser light (illumination light). The laser light (modulated light) modulated by the spatial light modulator 12 is transmitted through the TIR prism 11 by entering the TIR prism 11 at a angle less than the critical angle. Thereafter, a desired image is displayed by being projected onto a screen (not shown) via the projection optical system 13. As described above, the laser light (modulated light) projected on the screen forms an image on the screen having different states over time. As a result, speckle patterns formed on the screen also vary with time, and thus a plurality of speckle patterns are superimposed by the human eye. As a result, the speckle pattern is averaged, so that a specific speckle pattern is hardly recognized and speckle is reduced.

FIG. 2 is a conceptual diagram for explaining the operation of the speckle removing unit 8. Hereinafter, the operation of the speckle removing unit 8 will be described in detail with reference to FIG.
As illustrated in FIG. 2, the speckle removing unit 8 includes a liquid crystal cell 6 and a birefringent plate 7 in order from the light source side.

  The liquid crystal cell 6 is controlled to an ON state and an OFF state over time by a control unit 9 (not shown). When the liquid crystal cell 6 is in the ON state, for example, the illumination light incident as S-polarized light is emitted as P-polarized light. When the liquid crystal cell 6 is in the OFF state, for example, illumination light incident as S-polarized light is transmitted as S-polarized light. That is, the liquid crystal cell 6 functions as a polarization direction conversion unit that switches the polarization direction of illumination light incident with time.

  The birefringent plate 7 changes the optical path according to the polarization direction of the illumination light incident through the liquid crystal cell 6. For example, if the illuminating light is S-polarized light, the birefringent optical path changing means folds the straight plate 7 and exits. If the illumination light is P-polarized light, the optical path is translated in the birefringent plate 7 and emitted. That is, it functions as an optical path changing unit that changes the optical path of the illumination light in accordance with the polarization direction. More strictly, the birefringent plate 7 has an optical axis perpendicular to the vibration direction of S-polarized light.

  FIG. 2A illustrates a case where the illumination light 20 is incident as S-polarized light on the speckle removing unit 8 in which the liquid crystal cell 6 is in the OFF state. As illustrated in FIG. 2A, the illumination light 20 incident as S-polarized light is transmitted through the liquid crystal cell 6 as S-polarized light to the birefringent plate 7 because the liquid crystal cell 6 is controlled to be in the OFF state. Incident. Since the birefringent plate 7 has a characteristic of traveling straight with respect to S-polarized light, the illumination light 20 travels straight through the birefringent plate 7 and is emitted as S-polarized illumination light 20a.

On the other hand, FIG. 2B illustrates a case where the illumination light 20 is incident as S-polarized light on the speckle removal unit 8 in which the liquid crystal cell 6 is in the ON state. As illustrated in FIG. 2B, the illumination light 20 incident as S-polarized light is converted into P-polarized light by the liquid crystal cell 6 and is incident on the birefringent plate 7 because the liquid crystal cell 6 is controlled to be in the ON state. To do. Since the birefringent plate 7 has a characteristic of moving the optical path with respect to the P-polarized light, the illumination light 20 moves in parallel within the birefringent plate 7 and is emitted as the P-polarized illumination light 20b.

  As described above, in the illumination device 100a and the projection display device 100 of the present embodiment, the polarization direction of the illumination light is changed over time by the liquid crystal cell 6 and is incident on the birefringence plate 7 to be emitted from the birefringence plate 7. The optical path and polarization direction of the illumination light can be switched over time. For this reason, the spatial light modulator 12, and thus the screen (not shown) is illuminated with light of a plurality of optical paths that change over time, and a plurality of speckle patterns are generated at different positions. Further, since the plurality of speckle patterns are formed by laser beams having polarization directions orthogonal to each other, the speckle patterns have different patterns.

  As described above, in the present embodiment, speckle patterns different in time and space are generated. Further, the speckle pattern itself is mainly different depending on the polarization direction. For this reason, the speckle pattern is averaged as a whole, and the speckle can be efficiently reduced.

  Further, the birefringent plate 7 may be further vibrated. When the birefringent plate 7 vibrates in this way, the speckle pattern formed by the illumination light emitted from the birefringent plate 7 is temporally and spatially different. For this reason, a higher speckle reduction effect can be obtained.

  In this embodiment, since the speckle removing unit 8 is disposed in the illumination optical system (illumination device 100a), the influence on the image quality is reduced as compared with the case where it is disposed on the projection optical system 13 side. For this reason, the liquid crystal cell 6 only needs to operate at a speed having a speckle reduction effect, and a liquid crystal cell having a relatively low speed can be used as compared with the case where the liquid crystal cell 6 is disposed in the projection optical system 13 having a great influence on image quality. For example, the liquid crystal cell 6 (polarization direction conversion means) may be configured to switch the polarization direction of illumination light at a period of 60 Hz or more.

  In the case of this configuration, the balance of the light amounts of the S-polarized illumination light 20 a and the P-polarized illumination light 20 b is determined by controlling the state of the liquid crystal cell 6. For this reason, it is possible to change the ratio of each of the plurality of speckle patterns without changing the physical configurations of the illumination device 100a and the projection display device 100. This makes it possible to generate each speckle pattern at a rate that realizes more efficient speckle pattern reduction.

In this embodiment, it is desirable to use a device that does not depend on the polarization direction, such as a micromirror device, as the spatial light modulator 12. Further, by adding a change conversion element that aligns the polarization direction of the illumination light incident on the spatial light modulator 12 before the spatial light modulator 12, a reflective liquid crystal or a transmissive liquid crystal depending on the polarization direction is spatially modulated. It can also be used as a container.
<Second Embodiment>
The illumination device and the projection display device according to the present embodiment are modifications of the illumination device 100a and the projection display device 100 according to the first embodiment. For this reason, the same code | symbol is attached | subjected to the component which is common in the illuminating device 100a and the projection type display apparatus 100, and description is abbreviate | omitted.

FIG. 3 is a conceptual diagram for explaining the configuration and operation of the lighting apparatus according to the present embodiment.
The illumination device 200a and the projection display device 200 of the present embodiment are different only in that the illumination device 200a and the projection display device 200 are configured to further include a polarizing plate 14 with respect to the illumination device 100a and the projection display device 100, as illustrated in FIG. ing.

The laser light emitted from the laser light source 1 is originally emitted with a certain polarization direction, but the polarization direction may be disturbed before being emitted from the laser light source 1 and entering the liquid crystal cell 6. The polarizing plate 14 of the present embodiment plays a role of adjusting this disturbance, and plays a role of aligning the polarization direction of the laser light (illumination light) incident on the liquid crystal cell 6.

  In FIG. 3, an example in which the polarizing plate 14 is configured between the lens 5 and the liquid crystal cell 6 (not shown) is shown, but is not particularly limited thereto. Since it is sufficient that the laser light (illumination light) incident on the liquid crystal cell 6 can be made uniform, it may be in the optical path between the laser light source 1 and the liquid crystal cell 6 (polarization direction conversion means).

  FIG. 3A illustrates a case where the illumination light is incident on the speckle removing unit 8 (speckle removing means) in which the liquid crystal cell 6 is in the OFF state. As illustrated in FIG. 3A, the illumination light 20 in which S-polarized light and P-polarized light are mixed passes only the S-polarized light through the polarizing plate 14, so that only the S-polarized light enters the liquid crystal cell 6. . Since the liquid crystal cell 6 is controlled to be in the OFF state, the illumination light 20 passes through the liquid crystal cell 6 as S-polarized light and enters the birefringent plate 7. Since the birefringent plate 7 has a characteristic of traveling straight with respect to S-polarized light, the illumination light 20 travels straight through the birefringent plate 7 and is emitted as S-polarized illumination light 20a.

  On the other hand, FIG. 3B illustrates a case where the illumination light is incident on the speckle removal unit 8 in which the liquid crystal cell 6 is in the ON state. As illustrated in FIG. 3B, the illumination light 20 in which S-polarized light and P-polarized light are mixed is transmitted only through the S-polarized light by the polarizing plate 14, so that only the S-polarized light enters the liquid crystal cell 6. . Since the liquid crystal cell 6 is controlled to be in the ON state, the illumination light 20 is converted into P-polarized light by the liquid crystal cell 6 and enters the birefringent plate 7. Since the birefringent plate 7 has a characteristic of changing the optical path with respect to P-polarized light, the illumination light 20 moves in parallel within the birefringent plate 7 and is emitted as P-polarized illumination light 20b.

  As described above, in this embodiment, the polarization direction of the incident light is aligned in a certain direction using the polarizing plate 14 before entering the liquid crystal cell 6, so that the polarization direction of the laser light that is illumination light in the illumination optical system. Even in the case of disturbance, the same effect as that of the first embodiment can be obtained. That is, in the present embodiment, speckle patterns that are temporally and spatially different are generated. Further, the speckle pattern itself is mainly different depending on the polarization direction. For this reason, the speckle pattern is averaged as a whole, and the speckle can be efficiently reduced.

In the case of this configuration, since the polarization direction of incident light is further aligned as compared with the first embodiment by using the polarizing plate 14, the S-polarized illumination light 20a and the P-polarized illumination light 20b Switching control can be performed more accurately. This makes it possible to generate each speckle pattern at a rate that achieves more accurate and efficient speckle pattern reduction. <Third Embodiment>
The illumination device and the projection display device according to the present embodiment are modifications of the illumination device 100a and the projection display device 100 according to the first embodiment. For this reason, the same code | symbol is attached | subjected to the component which is common in the illuminating device 100a and the projection type display apparatus 100, and description is abbreviate | omitted.

FIG. 4 is a diagram illustrating a configuration of the projection display device according to the present embodiment.
As illustrated in FIG. 4, the illumination device 300 a and the projection display device 300 according to the present embodiment only have a configuration of a speckle removal unit 8 (speckle removal means) with respect to the illumination device 100 a and the projection display device 100. Is different.

The speckle removing unit 8 of the present embodiment is the same as the speckle removing unit 8 of the first embodiment in that the liquid crystal cell 6 and the birefringent plate 7 are configured, but the birefringent plates 7 have different thicknesses. The difference is that it is composed of three birefringent plates, a birefringent plate 7a, a birefringent plate 7b, and a birefringent plate 7c.

  The birefringent plate 7 (birefringent plate 7a, birefringent plate 7b, birefringent plate 7c) of the present embodiment is configured to be switchable by an unillustrated insertion / removal mechanism in the illumination device 300a. The birefringence plate 7 is switched to adjust the optical path emitted from the birefringence plate 7. When each birefringent plate has the same birefringence, the amount of change of the optical path of the birefringent plate 7 increases as the thickness of the birefringent plate 7 increases. For this reason, it is possible to adjust the optical path change amount by preparing a plurality of birefringent plates 7 having different thicknesses and switching them as necessary. More specifically, by switching the birefringent plate 7, the optical path of the S-polarized illumination light 20a when the liquid crystal cell 6 is in the OFF state and the optical path of the P-polarized illumination light 20b when the liquid crystal cell 6 is in the ON state. And the distance between the optical paths can be changed. That is, the distance between the optical path of the illumination light 20b whose optical path is changed by the birefringent plate 7 (optical path changing means) and the optical path of the illumination light 20a whose optical path is not changed by the birefringent plate 7 (optical path changing means) is variably changed. can do.

  As described above, also in this embodiment, the same effect as that of the first embodiment can be obtained. That is, in the present embodiment, temporally and spatially different speckle patterns are generated, and the speckle patterns themselves are mainly different depending on the polarization direction. For this reason, the speckle pattern is averaged as a whole, and speckle can be reduced.

  Moreover, in this embodiment, the optical path change amount by the birefringent plate 7 can be adjusted by comprising the several birefringent plate 7 from which thickness differs so that insertion or removal is possible. That is, it is possible to adjust the way in which the speckle patterns overlap (distance). For this reason, it is possible to reduce speckles more efficiently by adjusting the way in which speckle patterns are superimposed according to the image.

In the present embodiment, the example in which the birefringent plate 7 is configured by a plurality of birefringent plates having different thicknesses is shown, but the present invention is not particularly limited thereto. For example, the optical path change amount may be adjusted by changing the birefringence of each birefringent plate constituting the birefringent plate 7. Further, the optical path change amount may be adjusted by making the birefringence and thickness of each birefringent plate constituting the birefringent plate 7 different.
<Fourth Embodiment>
The illumination device and the projection display device according to the present embodiment are modifications of the illumination device 100a and the projection display device 100 according to the first embodiment. For this reason, the same code | symbol is attached | subjected to the component which is common in the illuminating device 100a and the projection type display apparatus 100, and description is abbreviate | omitted.

FIG. 5 is a diagram illustrating a configuration of the projection display device according to the present embodiment.
As illustrated in FIG. 5, the illumination device 400 a and the projection display device 400 of the present embodiment are subsequent to the speckle removal unit 8 (speckle removal means) with respect to the illumination device 100 a and the projection display device 100. Furthermore, the point that the speckle removal unit 18 is configured is different. The speckle removing unit 18 (speckle removing means) includes a liquid crystal cell 16 and a birefringent plate 17 as illustrated in FIG. That is, the speckle removing unit (speckle removing unit) according to the present embodiment includes the speckle removing unit 8 and the speckle removing unit 18, and the liquid crystal cell 6 (first polarization direction converting unit) in order from the light source side. And a birefringent plate 7 (first optical path changing means), a liquid crystal cell 16 (second polarization direction changing means), and a birefringent plate 17 (second optical path changing means). The operation of the speckle removing unit 8 and the speckle removing unit 18 will be described. The operation of the speckle removal unit 8 is the same as that of the first embodiment. That is, as illustrated in FIG. 5, the speckle removal unit 8 emits S-polarized illumination light 20 a and P-polarized illumination light 20 b over time by switching the state of the liquid crystal cell 6.

Hereinafter, the operation of the speckle removing unit 18 will be described. First, the liquid crystal cell 16 changes the direction of polarization of incident illumination light and emits it under the control of a control unit (not shown). That is, it functions as a polarization direction conversion means for switching the polarization direction of the incident illumination light over time. Specifically, the case where the S-polarized illumination light 20a is emitted as it is as the S-polarized illumination light and the case where it is converted into the P-polarized illumination light and emitted are switched over time. Further, the case where the P-polarized illumination light 20b is emitted as it is as the P-polarized illumination light and the case where it is converted into the S-polarized illumination light and emitted are switched over time. Thereby, the illumination light emitted from the liquid crystal cell 16 has a total of four states on the two optical paths over time. The control unit that controls the liquid crystal cell 16 may be the same as or different from the control unit that controls the liquid crystal cell 6. However, a configuration in which the liquid crystal cell 6 and the liquid crystal cell 16 are controlled in synchronization is desirable.

  The birefringent plate 17 changes the optical path according to the polarization direction of the illumination light incident through the liquid crystal cell 16. That is, it functions as an optical path changing unit that changes the optical path of the illumination light in accordance with the polarization direction. Here, the birefringent plate 17 has an optical axis perpendicular to the vibration direction of the P-polarized light. The optical axis of the birefringent plate 17 is perpendicular to the optical axis of the birefringent plate 7, and the direction in which the optical path is changed by the birefringent plate 17 is also perpendicular to the case of the birefringent plate 7. That is, the birefringent plate 17 (second polarization direction converting means) changes the optical path of the illumination light in a direction different from that of the birefringent plate 7 (first optical path changing means). More specifically, if the illumination light is P-polarized light, the birefringent plate 17 travels straight through the birefringent plate 17 and exits. If it is S-polarized light, the birefringent plate 17 translates the optical path and emits the light. It has the characteristic to do. For this reason, the illumination light having two optical paths in a total of four states emitted from the liquid crystal cell 16 incident on the birefringent plate 17 is emitted from the birefringent plate 17 without changing the optical path if it is P-polarized ( In the case of illumination light 20c, illumination light 20e) and S-polarized light, the light path is changed in a direction perpendicular to the optical path change by the birefringent plate 7 and emitted (illumination light 20d, illumination light 20f). As a result, the illumination light emitted from the birefringent plate 17 has a total of four states over time on the four optical paths (illumination light 20c, illumination light 20d, illumination light 20e, and illumination light 20f).

  FIG. 6 is a diagram illustrating a change in the optical path of the luminous flux emitted from the speckle removing unit illustrated in FIG. The illumination light 20c indicates illumination light that has been transmitted through the birefringent plate 7 and the birefringent plate 17, and the positions of the light beams are illustrated. Illumination light 20d indicates illumination light that travels straight through the birefringent plate 7 and whose optical path is changed by the birefringent plate 17, and the position of the light beam is illustrated. The illumination light 20d illuminates a position different from the illumination light 20c due to an optical path change indicated by an optical path change 18a in the birefringent plate 17. Illumination light 20e indicates illumination light that has changed its optical path at the birefringent plate 7 and travels straight through the birefringent plate 17, and the position of the light beam is illustrated. The illumination light 20e illuminates a position different from the illumination light 20c and the illumination light 20d due to the change in the optical path indicated by the optical path change 8a in the birefringent plate 7. The illumination light 20f indicates illumination light whose optical path is changed by the birefringent plate 7 and the birefringent plate 17, and the position of the light beam is illustrated. The illumination light 20f has an optical path change indicated by the optical path change 8a in the birefringent plate 7, and further an optical path change indicated by the optical path change 18b in the birefringent plate 17, whereby the illumination light 20c and the illumination light A position different from 20d and illumination light 20e is illuminated.

  By thus configuring the optical axes of the birefringent plate 7 and the birefringent plate 17 so as to be vertical, the illumination range of the four states of illumination light emitted from the birefringent plate 17 is 1 as illustrated in FIG. The deviation in the direction can be suppressed. It is desirable that such a change in the illumination range with time is not more than half the pitch of the pixel portion of the spatial light modulator 12. That is, it is desirable that the illumination device 400a is configured to illuminate the spatial light modulator 12 by changing the illumination range by a half or less of the pitch of the pixel portion of the spatial light modulator 12 over time. Thereby, since it is not necessary to provide an unnecessarily large illumination range for the spatial light modulator 12, the spatial light modulator 12 can be efficiently illuminated with the laser light (illumination light) emitted from the laser light source 1. it can. It should be noted that the configuration in which the change of the illumination range with time is within half the pitch of the pixel portion is similarly desirable even in the case of the first to third embodiments described above.

As described above, in this embodiment, by using the speckle removal unit 18 in addition to the speckle removal unit 8, it is possible to generate more speckle patterns that are spatially different from those in the first embodiment. . In addition, as in the first embodiment, speckle patterns that differ in terms of time are generated, and that speckle patterns themselves differ mainly due to differences in polarization direction. For this reason, speckle patterns are averaged as a whole, and speckles can be reduced more efficiently than in the first embodiment.

In this embodiment, a polarizing plate may be used as in the second embodiment. In addition, a plurality of birefringent plates may be switched and used as in the third embodiment. By using a polarizing plate or a plurality of birefringent plates, the same effect as in the second and third embodiments can be obtained, and a higher speckle reduction effect can be obtained.
<Fifth Embodiment>
The illumination device and the projection display device according to the present embodiment are modifications of the illumination device 100a and the projection display device 100 according to the first embodiment. For this reason, the same code | symbol is attached | subjected to the component which is common in the illuminating device 100a and the projection type display apparatus 100, and description is abbreviate | omitted.

  FIG. 7 is a conceptual diagram for explaining the configuration of the speckle removing unit according to the present embodiment. As illustrated in FIG. 7, the illumination device 500a and the projection display device 500 of the present embodiment are different from the first embodiment only in the configuration of the speckle removal unit. Specifically, the speckle removing unit 8a (speckle removing unit) of the present embodiment includes a liquid crystal cell 6 serving as a polarization direction converting unit and a birefringent plate 7 serving as an optical path changing unit formed as one unit. . Thus, by forming the liquid crystal cell 6 and the birefringent plate 7 integrally as one unit, the space required for the speckle removing portion 8a can be reduced. In addition, the speckle removing unit 8a can be easily handled. Specifically, it is important that the optical axis of the birefringent plate 7 is oriented in an appropriate direction, but by integrating the liquid crystal cell 6 in this way, the direction of the optical axis with respect to the liquid crystal cell 6 becomes constant. Therefore, it is possible to reduce the burden of work when the speckle removing unit 8a is incorporated in the illumination device 500a or the projection display device 500.

  As described above, also in this embodiment, the same effect as that of the first embodiment can be obtained. That is, in the present embodiment, temporally and spatially different speckle patterns are generated, and the speckle patterns themselves are mainly different depending on the polarization direction. For this reason, the speckle pattern is averaged as a whole, and the speckle can be efficiently reduced.

In this embodiment, a polarizing plate may be used as in the second embodiment. In addition, a plurality of birefringent plates may be switched and used as in the third embodiment. By using a polarizing plate or a plurality of birefringent plates, the same effect as in the second and third embodiments can be obtained, and a higher speckle reduction effect can be obtained.
<Sixth Embodiment>
The illumination device and the projection display device of this embodiment are modifications of the illumination device 400a and the projection display device 400 of the fourth embodiment. For this reason, the same code | symbol is attached | subjected to the component which is common in the illuminating device 400a and the projection type display apparatus 400, and description is abbreviate | omitted.

FIG. 8 is a conceptual diagram for explaining the configuration of the speckle removing unit according to the present embodiment. As illustrated in FIG. 7, the illumination device 600a and the projection display device 600 of the present embodiment are different from the fourth embodiment only in the configuration of the speckle removal unit. Specifically, in the speckle removing unit 8b (speckle removing means) of the present embodiment, the liquid crystal cell 6, the birefringent plate 7, the liquid crystal cell 16, and the birefringent plate 17 are formed as one unit. As described above, the liquid crystal cell 6, the birefringent plate 7, the liquid crystal cell 16 and the birefringent plate 17 are integrally formed as one unit, so that the space required for the speckle removing portion 8b can be reduced. In addition, the speckle removal unit 8b can be easily handled. Specifically, it is important for the birefringent plate 7 and the birefringent plate 17 to have their optical axes oriented in an appropriate direction.
, The direction of the optical axis with respect to the liquid crystal cell 6 and the liquid crystal cell 16 becomes constant. For this reason, the burden of the operation | work at the time of incorporating the speckle removal part 8b in the illuminating device 600a or the projection type display apparatus 600 can be reduced.

  As described above, also in this embodiment, the same effect as that of the fourth embodiment can be obtained. That is, in the present embodiment, temporally and spatially different speckle patterns are generated, and the speckle patterns themselves are mainly different depending on the polarization direction. For this reason, the speckle pattern is averaged as a whole, and the speckle can be efficiently reduced.

  In this embodiment, a polarizing plate may be used as in the second embodiment. In addition, a plurality of birefringent plates may be switched and used as in the third embodiment. By using a polarizing plate or a plurality of birefringent plates, the same effect as in the second and third embodiments can be obtained, and a higher speckle reduction effect can be obtained.

  Needless to say, the present invention is not limited to the configuration exemplified in the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

It is a figure which shows an example of a structure of the projection type display apparatus which concerns on one Embodiment of this invention. It is a conceptual diagram for demonstrating the effect | action of the speckle removal part which concerns on one Embodiment of this invention. It is a conceptual diagram for demonstrating the structure and effect | action of the modification of the illuminating device which concerns on one Embodiment of this invention. It is a figure which shows the modification of a structure of the projection type display apparatus which concerns on one Embodiment of this invention. It is a conceptual diagram for demonstrating the structure and effect | action of the modification of the speckle removal part which concerns on one Embodiment of this invention. It is a figure which shows the change of the optical path of the light beam of the illumination light inject | emitted from the speckle removal part illustrated by FIG. It is a conceptual diagram for demonstrating the structure of the other modification of the speckle removal part which concerns on one Embodiment of this invention. It is a conceptual diagram for demonstrating the structure of the further another modification of the speckle removal part which concerns on one Embodiment of this invention. It is a schematic diagram of the bundle fiber of a prior art. It is a figure explaining the structure of the projector apparatus of a prior art. It is a figure which shows the optical structure of the birefringent device of a prior art. It is a schematic block diagram of the scanning display apparatus of a prior art. It is a block diagram which shows schematic structure of the projection display apparatus of a prior art.

Explanation of symbols

100, 200, 300, 400, 500, 600 Projection display devices 100a, 200a, 300a, 400a, 500a, 600a Illumination device 1 Laser light source 1a Green (G) Laser light source 1b Blue (B) Laser light source 1c Red (R) Laser light source 2, 5, 10 Lens 3 Dichroic mirror 4 Rod integrator 6, 16 Liquid crystal cell 7, 17 Birefringence plate 8, 8 a, 8 b, 18 Speckle removal unit 9 Control unit 11 TIR prism 12 Spatial light modulator 13 Projection optics System 14 Polarizing plate 20, 20a, 20b, 20c, 20d, 20e, 20f Illumination light 700 Bundle fiber 700a, 700b, 700c, 700d Optical fiber 701 Space 702, 711 Laser light source 703 Motor 704 1/2 wavelength retardation plate 705 Drive unit 706 Lighting lens 707 G V
708, 712 Birefringent plates 709, 710 Birefringent media 709a, 710a Optical axis 713 Screen 714 Light source 715 Display liquid crystal panel 716, 718 Polarization direction control liquid crystal panel 717, 719 Quartz plate 720 Projection lens system

Claims (11)

A laser light source that emits illumination light;
An illumination optical system on which the illumination light is incident;
Speckle removing means disposed in the optical path of the illumination optical system,
The speckle removing means is
Polarization direction converting means for switching the polarization direction of the illumination light over time;
An illumination device comprising: an optical path changing unit that changes an optical path of the illumination light incident through the polarization direction conversion unit according to a polarization direction. The lighting device according to claim 1.
Furthermore, the illuminating device characterized by including the polarizing plate which aligns the polarization direction of the said illumination light in the optical path between the said laser light source and the said polarization direction conversion means. The lighting device according to claim 1 or 2,
The polarization direction conversion means includes a first polarization direction conversion means and a second polarization direction conversion means,
The optical path changing means includes a first optical path changing means and a second optical path changing means,
The speckle removing unit includes a first polarization direction converting unit, a first optical path changing unit, a second polarization direction converting unit, and a second optical path changing unit in order from the light source side. A lighting device. The lighting device according to claim 3.
The second optical path changing means changes the optical path of the illumination light in a direction different from that of the first optical path changing means. In the illuminating device of any one of Claim 1 thru | or 4,
The illuminating device characterized in that the polarization direction conversion means is a liquid crystal cell whose liquid crystal state is changed over time. In the illuminating device of any one of Claim 1 thru | or 4,
The optical path changing means variably changes a distance between the optical path of the illumination light whose optical path is changed by the optical path changing means and the optical path of the illumination light whose optical path is not changed by the optical path changing means. Lighting device. In the illuminating device of any one of Claim 1 thru | or 4,
The illumination device characterized in that the optical path changing means vibrates. In the illuminating device of any one of Claim 1 thru | or 4,
The illuminating device characterized in that the polarization direction conversion means switches the polarization direction of the illumination light at a period of 60 Hz or more. In the illuminating device of any one of Claim 1 thru | or 4,
The illuminating device characterized in that the polarization direction converting means and the optical path changing means are formed as one unit. The lighting device according to any one of claims 1 to 9,
A spatial light modulator that modulates light emitted from the illumination device;
A projection optical system that projects the light modulated by the spatial light modulator. The projection display device according to claim 10,
The spatial light modulator includes a plurality of pixel units,
The projection display device, wherein the illumination device illuminates the spatial light modulator while shifting an illumination range by half or less of a pitch of the pixel portion with time.