JP4983247B2 - Lighting device and projector - Google Patents

Description

  The present invention relates to a lighting device and a projector.

  In recent years, projectors are rapidly spreading. In addition to front projection projectors that have been used mainly for business presentation purposes, rear projectors have recently been gaining recognition as a form of large television (PTV: projection television). The greatest advantage of the projection system is that it can supply products with the same screen size at a lower price than direct-view displays such as liquid crystal televisions and PDPs. However, the price reduction is also progressing in the direct view type, and higher image quality performance is being demanded for the projector display device.

  A projector irradiates light modulation means such as a liquid crystal light valve with light emitted from a light source such as an arc lamp, and projects projection light modulated by the light modulation means onto a screen to display an image on the screen. . At this time, not only an image is displayed on the screen, but the entire screen appears glaring. This is due to luminance unevenness caused by the interference of light rays and is called speckle noise, so-called scintillation.

Here, the principle of scintillation generation will be briefly described. As shown in FIG. 9, the light emitted from the light source 101 passes through the liquid crystal light valve 102 and is projected onto the screen 104 by the projection lens 103. The projection light projected on the screen 104 is diffracted by the scattering structure of the screen 104 and diffused by acting like a secondary wave source. Two spherical waves from the secondary wave source appear as bright and dark stripes (interference fringes) between the screen 104 and the viewer by causing the light to strengthen or weaken according to the phase relationship between them. . When the viewer is focused on the image plane 105 where the interference fringes are generated, the viewer recognizes the interference fringes as scintillation for glaring the screen.
Scintillation gives an uncomfortable feeling to a viewer who wants to see an image formed on the screen surface as if a veil, a lace cloth, a spider web, or the like is stretched between the screen surface and the viewer. In addition, since the viewer sees a double image of the image on the screen and the scintillation and tries to match the viewpoint with each image, it causes great fatigue. Therefore, this scintillation gives a great stress to the viewer.

  In recent years, new light sources that replace conventional high-pressure mercury lamps have been developed. In particular, laser light sources are excellent in terms of energy efficiency, color reproducibility, long life, and instantaneous lighting. However, the projection light on the screen by the laser light source has very high coherence because the phases of the light beams in the adjacent areas are aligned. In addition, the coherent length of a laser light source can be as long as several tens of meters. Therefore, if the same light source is divided and recombined, the light synthesized through an optical path difference shorter than the coherent length causes strong interference. Thus, a clearer scintillation appears than when a high-pressure mercury lamp is used.

In view of this, a screen having a three-layer structure of a diffusion layer, a transparent layer (lenticular lens), and a diffusion layer and having optimized diffusibility has been proposed (for example, see Patent Document 1). Here, scintillation is reduced by increasing the randomness of interference spots by complicating the scattering layer.
In addition, by applying light, electric field, magnetic field, heat, stress, etc. to the light scattering layer, the shape, relative positional relationship and refractive index of the light scatterer contained in the light diffusion layer are temporally changed. (See, for example, Patent Document 2). Here, scintillation is prevented from occurring by temporally changing the scattering distribution and phase of the scattered wave by the light diffusion layer.
Japanese Patent Laid-Open No. 11-038512 JP 2001-100316 A

However, the following problems remain in the screen described above. That is, in the former screen, since the scattering state of the final scattering surface is fixed, the phase distribution of the space between the screen and the viewer that interferes with light rays emitted from each point on the scattering surface is also fixed. Therefore, the interference spots are also visually recognized as a fixed image. For this reason, the interference spots do not completely disappear, and in particular, a projector having a highly coherent laser light source can hardly obtain the effect. In addition, in such a configuration with high scattering, image blur may occur, and it is difficult to improve image quality.
The latter screen requires a large amount of driving energy to change the shape, relative positional relationship, refractive index, etc. of the light scatterer, and allows comfortable viewing with vibration, sound, unnecessary electromagnetic waves, and exhaust heat. May interfere. In a configuration in which the scattering layer moves in the focal direction, the size of the image changes. For this reason, the position of the contour line of the image in the horizontal direction also changes, which causes image blurring.

  SUMMARY An advantage of some aspects of the invention is that it provides an illumination device and a projector that further reduce scintillation and improve image quality.

The present invention employs the following configuration in order to solve the above problems. That is, the illumination device according to the present invention converts the light emitted from the light source and the light emitted from the light source into polarized light whose polarization direction changes over time and guides it to the irradiated surface of the irradiated member. A light guide member that guides the light emitted from the light source, and a driving unit that drives the light guide member around an optical axis, and the light guide member includes a converter. The member has an incident surface on which light emitted from the light source is incident, an emission surface that emits light, and a reflection surface that reflects the light incident from the incident surface toward the emission surface. Features.
The illumination device according to the present invention includes a light source that emits polarized light, and a conversion that converts the light emitted from the light source into polarized light whose polarization direction changes over time and guides it to the irradiated surface of the irradiated member. A light guide member that guides the light emitted from the light source, and a driving unit that drives the light guide member around an optical axis, and the light guide member. However, it is flexible and can guide light while maintaining the polarization state of the polarized light emitted from the light source, and the drive means guides the light exiting surface of the light guide member to the incident surface. It is driven around the optical axis of the member.
The illumination device includes a light source and a conversion unit that converts the light emitted from the light source into polarized light whose polarization direction changes with time and guides the light to the irradiated surface of the irradiated member.

In the present invention, for example, the interference fringes formed on the projection member are temporally changed by changing the polarization direction of the light projected onto the projection member such as a screen. This can further reduce scintillation and improve display image quality.
That is, when the polarization direction of the light incident on the irradiated member is changed with time, the scattering state of the light emitted from the irradiated member changes variously according to the polarization direction. And the pattern of the interference fringe visually recognized by the projection target member changes and becomes complicated. As a result, the light emitted from the projection member is time-integrated and averaged by the remaining characteristics of the viewer's eyes, so that the interference fringes are not visually recognized. This is due to the characteristic that the image appears to be displayed uniformly when the image is held for a certain period of time due to an afterimage in the human eye. Therefore, scintillation is further reduced and displayed image quality is improved.

In the illumination device according to the present invention, the light source emits polarized light, and the conversion unit guides the light emitted from the light source, and the light guide member is rotated around the axis of the optical axis. It is good also as providing the drive means to drive by.
In this invention, the polarization direction of the incident light to the irradiated member is temporally changed by temporally changing the polarization direction of the emitted light from the light guide member by the driving means.

In the illumination device according to the present invention, the light guide member has an incident surface on which light emitted from the light source is incident, an emission surface from which light is emitted, and directs light incident from the incident surface to the emission surface. It is good also as having a reflective surface to reflect.
In the present invention, the polarization direction of the light emitted from the exit surface is temporally changed by temporally changing the angle formed between the polarization direction of the incident light on the reflective surface and the reflective surface. That is, the change in the polarization direction of the incident angle on the reflecting surface and the reflected light changes according to the polarization direction of the incident light on the reflecting surface with respect to the reflecting surface. Thereby, the polarization direction of the emitted light from the emission surface of the light guide member is temporally changed by driving the light guide member and temporally changing the polarization direction with respect to the reflection surface.

In the illumination device according to the present invention, the light guide member is flexible and can guide light while maintaining a polarization state of the polarized light emitted from the light source. The exit surface of the optical member may be driven around the optical axis of the light guide member with respect to the incident surface.
In this invention, the exit surface is driven around the axis of the optical axis with respect to the entrance surface, so that the polarization direction of the exit light from the exit surface is temporally related to the polarization direction of the polarized light of the entrance light to the entrance surface. To change. Thereby, the polarization direction of the polarized light emitted from the exit surface of the light guide member changes with time.

In the illumination device according to the present invention, the light source emits non-polarized light, and the conversion unit transmits the polarized light having one polarization direction out of the non-polarized light emitted from the light source; Drive means for driving the polarization direction of the polarized light that can be transmitted through the polarization member around the axis of the optical axis may be provided.
In this invention, the polarization direction of the incident light to the irradiated member is temporally changed by temporally changing the polarization direction of the polarized light that can be transmitted through the polarizing member by the driving means.

In the illumination device according to the present invention, it is preferable that the polarizing member reflects polarized light having another polarization direction toward the light source.
In this invention, the polarized light other than the polarized light having the polarization direction transmitted through the polarizing member is reflected toward the light source, so that the polarized light having the other polarization direction can be reused and emitted from the light source. The utilization efficiency of the emitted light is improved.

In the illumination device according to the present invention, the conversion unit includes a light guide member that guides light emitted from the light source, and an incident area of the light emitted from the light source on an incident surface of the light guide member It is preferable that a reflective film having an opening is provided.
In this invention, the light that is reflected by the polarizing member and guided through the light guiding member is reflected again by the reflecting film toward the polarizing member, so that it is possible to efficiently reuse the polarized light having other polarization directions. The utilization efficiency of light emitted from the light source is further improved.

Moreover, it is preferable that the illuminating device concerning this invention is equipped with the optical fuse which interrupts | blocks the light which injects into the said to-be-irradiated surface when the light quantity inject | emitted from the said light source exceeds predetermined value.
According to the present invention, it is possible to prevent other optical members and the like from being affected by an excessive amount of light incident.

According to another aspect of the present invention, there is provided a projector comprising: the above-described illumination device; and a light modulation unit that modulates light emitted from the illumination device in accordance with an image signal. The light modulated by the light modulation unit is projected. It projects on a member.
In the present invention, as described above, since the incident angle of the projection light to the projection target changes with time, the interference fringes change with time. This can further reduce scintillation and improve display image quality.

The projector according to the present invention preferably includes a plurality of the illumination devices, and the plurality of light sources are connected to the same cooling unit.
In the present invention, by connecting a plurality of light sources to the same cooling unit, the light sources can be cooled in a lump, and the apparatus can be downsized.

[First Embodiment]
Hereinafter, a first embodiment of an illumination device and a projector according to the present invention will be described with reference to the drawings. 1A is a schematic perspective view showing a rear projector, FIG. 1B is a side sectional view, FIG. 2 is a schematic configuration diagram showing a projection optical system, and FIG. 3 is a schematic perspective view showing a laser light source. .

As shown in FIG. 1, a rear projector (projector) 1 according to the present embodiment includes a housing 2 and a screen (projected member) 3 provided on the front surface of the housing 2 to project an image. Openings 5 for outputting sound from speakers are formed on the left and right sides of the front panel 4 provided below the housing 2.
Further, the rear projector 1 includes a projection optical system 10 provided in the housing 2, and reflection mirrors 11 and 12 that reflect light emitted from the projection optical system 10 and project it on the screen 3 in an enlarged manner.

  As shown in FIG. 2, the projection optical system 10 includes a red light illumination device 15A that emits red light, a green light illumination device 15B that emits green light, a blue light illumination device 15C that emits blue light, and a dichroic. Mirrors 16A, 16B, reflection mirrors 17A, 17B, a mirror device (irradiated member, light modulating means) 18 that modulates laser light emitted from each of the illumination devices 15A-15C, and a projection lens 19 are provided. . In FIG. 2, illustration of the reflection mirrors 11 and 12 disposed between the projection lens 19 and the screen 3 is omitted.

First, the red light illumination device 15A will be described. In addition, in this embodiment, since the structure of each illuminating device 15A-15C is the same, only red light illuminating device 15A is demonstrated and description of green light illuminating device 15B and blue light illuminating device 15C is abbreviate | omitted.
The red light illumination device 15A includes a laser light source 21A.

  The laser light source 21A is configured to emit red laser light from its emission end toward the dichroic mirror 16A. As shown in FIG. 3, the laser light source 21A includes a plurality of sets of laser elements (light sources) 25, a lens 26 for condensing the light emitted from the laser element 25, and the polarization direction of the light emitted from the lens 26 over time. And a conversion unit 27 that changes to a CGH (Computer Generated Hologram) element 28.

A plurality of laser elements 25 are arranged in an array, and are configured to emit red laser light, which is polarized light having one polarization direction, toward the lens 26 from its emission end.
The conversion unit 27 includes a dove prism (light guide member) 31 that guides the light emitted from the lens 26 and an actuator (drive means) 32 that drives the dove prism 31 around the axis of the optical axis.
The dove prism 31 is a trapezoidal prism having a trapezoidal cross section including the optical axis and a rectangular cross section perpendicular to the optical axis, and the entrance surface 31a and the exit surface 31b intersect the optical axis non-perpendicularly. . The Dove prism 31 bends light incident on the incident surface 31a toward the reflecting surface 31c, which is one of the four side surfaces, reflects the light on the reflecting surface 31c, and then outwards from the exit surface 31b. It is configured to be bent and ejected. Here, the incident light on the incident surface 31a and the emitted light from the exit surface 31b are substantially parallel.
Further, the Dove prism 31 rotates the polarized light incident on the incident surface 31a by an angle approximately twice the angle formed by the polarization direction of the polarized light incident on the reflecting surface 31c and the reflecting surface 31c, and exits from the exit surface 31b. It is the composition to do.

The actuator 32 is composed of a piezo actuator mainly composed of a piezo element that expands or contracts by applying a voltage, for example. Here, the piezo element has a configuration in which piezo films and electrodes on a thin film are alternately stacked in order to increase the amount of displacement. The actuator 32 is provided on the reflecting surface 31c of the Dove prism 31, and is configured to swing the Dove prism 31 about an axis parallel to the optical axis. Therefore, the angle formed between the polarization direction of the incident light to the Dove prism 31 and the reflecting surface 31c changes with time. Here, the oscillation frequency of the Dove prism 31 by the actuator 32 is 60 Hz, for example, and the change width of the reflecting surface 31c of the Dove prism 31 by the actuator 32 is ± 45 °, for example. That is, the change width of the polarization direction of the polarized light emitted from the Dove prism 31 by the actuator 32 is, for example, ± 90 °.
The actuator 32 is not limited to an actuator using a piezo element that expands or contracts due to the application of a voltage. If the Dove prism 31 can be swung around an axis, an electrostatic force that expands and contracts by the electrostatic force of the electromagnetic actuator that expands and contracts by electromagnetic force can be used. Other actuators such as an actuator may be used.

  The CGH element 28 is a hologram element that forms interference fringes artificially created by calculation with a computer on a hologram original plate. The CGH element 28 is configured to uniformize the red laser light emitted from the laser element 25 and to uniformly irradiate the entire image display area (irradiated surface) of the mirror device 18 with the red laser light. This CGH element 28 is suitable because it can freely set the division region of the diffraction grating and does not cause an aberration problem. Note that a microlens array may be used instead of the CGH element 28 as long as the laser light emitted from the laser element 25 can be made uniform.

Also, an optical fuse 35 is provided between the laser light source 21A and the dichroic mirror 16A to block the red laser light from being guided when the amount of red laser light emitted from the laser light source 21A exceeds a predetermined value. . The optical fuse 35 is made of a material that is transparent to a light amount that is equal to or less than a predetermined value and that is not transparent to a light amount that exceeds a predetermined value.
The laser light source 21A is configured to emit red laser light from its emission end toward the dichroic mirror 16A. Further, the laser light source 21A is connected to a cooling unit 36 configured by, for example, a heat sink for cooling the laser light source 21A.

  As described above, since the green light illumination device 15B and the blue light illumination device 15C have the same configuration as the red light illumination device 15A, the laser light source (light source) 21B that emits green laser light and the blue laser light are emitted. Each is provided with a laser light source (light source) 21C for emitting. These laser light sources 21 </ b> A to 21 </ b> C are arranged close to each other and connected to the same cooling unit 36.

The dichroic mirror 16A is provided with a dielectric multilayer film that transmits red light and reflects green light. The dichroic mirror 16B is provided with a dielectric multilayer film that transmits red light and green light and reflects blue light.
The reflection mirror 17A is configured to reflect the green laser light emitted from the green light illumination device 15B toward the dichroic mirror 16A. The reflection mirror 17B is configured to reflect the blue laser light emitted from the blue light illumination device 15C toward the dichroic mirror 16B.

The mirror device 18 includes a plurality of micromirrors arranged in a matrix corresponding to the pixels of the image in the image display area, and drive means (not shown) for changing the direction of the reflecting surface of the micromirror so that the micromirror can be swung. And. Then, the mirror device 18 controls the emission direction of each laser beam incident on the basis of the supplied video signal, so that each color light is timed into modulated light projected and displayed on the screen 3 and invalid light not projected and displayed. It is the structure which modulates.
The projection lens 19 is configured to magnify and project the image modulated by the mirror device 18 onto the screen 3.

In the rear projector 1 configured as described above, the red laser light emitted from the red light illumination device 15A passes through the dichroic mirrors 16A and 16B and reaches the mirror device 18. Further, the green laser light emitted from the green light illumination device 15B is reflected by the reflection mirror 17A and the dichroic mirror 16A, and passes through the dichroic mirror 16B to reach the mirror device 18. Then, the blue laser light emitted from the blue light illumination device 15C is reflected by the reflection mirror 17B and the dichroic mirror 16B and reaches the mirror device 18.
Each laser beam incident on the mirror device 18 is modulated based on an image signal supplied to the mirror device 18. Then, the light is projected onto the screen 3 through the projection lens 19 and the reflection mirrors 11 and 12.

Here, in the red light illumination device 15A, red laser light having one polarization direction emitted from the laser element 25 is incident from the incident surface 31a of the Dove prism 31 and reflected by the reflecting surface 31c, and then from the emitting surface 31b. The light is emitted toward the mirror device 18 through the CGH element 28.
At this time, the actuator 32 provided on the reflecting surface 31c of the dove prism 31 swings the dove prism 31 around the axis of the optical axis at a frequency of 60 Hz, for example, according to the applied electric signal. As a result, the angle formed between the polarization direction of the red laser light incident on the reflecting surface 31c of the Dove prism 31 and the reflecting surface 31c changes periodically. Here, the polarization direction of the reflected light from the reflection surface 31c changes according to the angle formed by the polarization direction of the incident light on the reflection surface 31c and the reflection surface 31c. For this reason, the polarization direction of the red laser light emitted from the exit surface 31b of the Dove prism 31 and incident on the mirror device 18 changes periodically as shown in FIGS. Therefore, the polarization direction of the red laser light incident on the screen 3 changes with time.

At this time, since the amount of oscillation of the Dove prism 31 by the actuator 32 is ± 45 °, the amount of change in the polarization direction of the light emitted from the Dove prism 31 is ± 90 °. The red laser light uniformly irradiates the entire image display area of the mirror device 18.
In the green light illumination device 15B and the blue light illumination device 15C, the polarization directions of the green laser light and the blue laser light with respect to the screen 3 are temporally changed as in the red light illumination device 15A.

  The pattern of interference fringes generated on the screen 3 changes according to the polarization direction of the light projected onto the screen 3. And the polarization direction of projection light is changing periodically with the frequency of 60 Hz, for example by the actuator 32 provided in each illuminating device 15A-15C. For this reason, the scattering state of the light emitted from the screen 3 changes variously according to the polarization direction of the laser light incident on the screen 3, and the pattern of interference fringes visually recognized on the screen 3 changes over time and becomes complicated. To do. Here, the human eye has a characteristic that the image is visually recognized in a state where the image is uniformly displayed because the image is held for a certain period of time due to the afterimage. As a result, the interference fringe pattern formed on the screen 3 is time-integrated and averaged by the afterimage characteristics of the viewer's eyes. At this time, since the amount of change in the polarization direction of the light projected onto the screen 3 is ± 90 °, the interference fringe pattern is sufficiently complicated. Therefore, the interference fringe pattern averaged by the time integration is not visually recognized by the viewer.

As described above, according to the illuminating devices 15A to 15C and the rear projector 1 in the present embodiment, the polarization direction of the light incident on the screen 3 is periodically changed by the actuator 32, so that the interference fringes formed on the screen 3 Changes over time. This can further reduce scintillation and improve display image quality.
Further, by providing the optical fuse 35 between the laser light source 21A and the Dove prism 31, it is possible to prevent an excessive amount of laser light from being incident on optical members such as the dichroic mirrors 16A and 16B and the mirror device 18, and illumination. The reliability of the devices 15A to 15C is improved.
Then, by connecting the laser light sources 21A to 21C constituting the illumination devices 15A to 15C to the same cooling unit 36, the laser light sources 21A to 21C can be integrally cooled, and the rear projector 1 can be reduced in size.

[Second Embodiment]
Next, a second embodiment of the illumination device and the projector according to the present invention will be described with reference to the drawings. Here, FIG. 5 is a schematic perspective view showing a laser light source. In this embodiment, since the configuration of the laser light source is different from that of the first embodiment, this point will be mainly described, and the same reference numerals are given to the components described in the above embodiment, and the description thereof will be omitted. To do. Also in this embodiment, since the configurations of the red light illumination device, the green light illumination device, and the blue light illumination device are the same, only the red light illumination device will be described, and the green light illumination device and the blue light illumination device will be described. Is omitted.

In the red light illumination device 50 according to the present embodiment, as shown in FIG. 5, the conversion unit 52 of the laser light source 51 includes a light guide member 56 including three reflection mirrors 53, 54, and 55, and the reflection mirror 54 on the optical axis. And an actuator 57 that swings around an axis.
The reflection mirror 53 is configured to cause red laser light emitted from the lens 26 to be incident on the reflection surface 53 a and to be reflected toward the reflection mirror 54. An incident surface of the light guide member 56 is configured by the reflection surface 53a.
The reflection mirror 54 is configured to reflect the reflected light from the reflection mirror 53 toward the reflection mirror 55 on the reflection surface 54a.
The reflection mirror 55 is configured to reflect the reflected light from the reflection mirror 54 toward the CGH element 28. An exit surface of the light guide member 56 is configured by the reflection surface 55a.
The actuator 57 is configured by, for example, a piezo actuator, and is configured to swing the reflecting mirror 54 around the optical axis with a variation of ± 45 ° at a frequency of 60 Hz, for example.

In the red light illumination device 50 configured as described above, the red laser light emitted from the laser element 25 enters the reflection mirror 53 and is reflected by the reflection mirrors 53 and 54 and then further reflected by the reflection mirror 55. reflect. Then, the red laser light reflected by the reflecting mirror 55 irradiates the entire image display area of the mirror device 18 through the CGH element 28 uniformly.
At this time, the reflecting surface 54 a of the reflecting mirror 54 is periodically swung around the optical axis by the actuator 57. The angle between the polarization direction of the incident light on the reflecting surface 54a and the reflecting surface 54a changes periodically. Thereby, the polarization direction of the reflected light from the reflective surface 55a changes periodically. Therefore, the polarization direction of the red laser light with respect to the screen 3 changes periodically.

  As described above, the red light illumination device 50 and the rear projector in the present embodiment also have the same operations and effects as those in the first embodiment described above.

[Third Embodiment]
Next, a third embodiment of the illumination device and the projector according to the present invention will be described with reference to the drawings. Here, FIG. 6 is a schematic perspective view showing a laser light source. In this embodiment, since the configuration of the laser light source is different from that of the first embodiment, this point will be mainly described, and the same reference numerals are given to the components described in the above embodiment, and the description thereof will be omitted. To do. Also in this embodiment, since the configurations of the red light illumination device, the green light illumination device, and the blue light illumination device are the same, only the red light illumination device will be described, and the green light illumination device and the blue light illumination device will be described. Is omitted.

As shown in FIG. 6, the red light illumination device 60 in the present embodiment includes an optical fiber 63 that guides the red laser light emitted from the lens 26 by the conversion unit 62 of the laser light source 61, and an actuator 64 that twists the optical fiber 63. And.
The optical fiber 63 is a polarization maintaining fiber that can guide the red laser light while maintaining the polarization direction of the red laser light. The optical fiber 63 is formed in the groove 65a formed in the holding member 65 and having a substantially V-shaped cross section. It is fixed.
The actuator 64 is provided on the distal end side of the optical fiber 63 in the holding member 65, and includes, for example, a pair of electrodes 66A and 66B that generate an attractive force when a voltage is applied. The actuator 64 is configured to twist the exit surface of the optical fiber 63 at a frequency of, for example, 60 Hz with a variation of, for example, ± 90 ° with respect to the incident surface about the optical axis of the optical fiber 63. Accordingly, the polarization direction of the incident light to the optical fiber 63 and the polarization direction of the emitted light are periodically changed.

In the red light illumination device 60 configured as described above, the red laser light emitted from the laser element 25 enters the optical fiber 63 as described above. Then, the red laser light emitted from the optical fiber 63 uniformly irradiates the entire image display region of the mirror device 18 through the CGH element 28.
At this time, the vicinity of the emission surface of the optical fiber 63 is periodically twisted around the axis of the optical axis with respect to the incident surface by the actuator 64. As a result, the polarization direction of the red laser light emitted from the optical fiber 63 changes with time. Therefore, the polarization direction of the red laser light with respect to the screen 3 changes with time.

  As described above, the red light illumination device 60 and the rear projector including the same in the present embodiment also have the same operations and effects as those in the first and second embodiments described above.

[Fourth Embodiment]
Next, a fourth embodiment of the illumination device and the projector according to the present invention will be described with reference to the drawings. Here, FIG. 7 is a schematic perspective view showing an LED (Light Emitting Diode) light source. In this embodiment, since the configuration of the lighting device is different from that of the first embodiment, this point will be mainly described, and the same reference numerals are given to the components described in the above embodiment, and the description thereof will be omitted. To do. Also in this embodiment, since the configurations of the red light illumination device, the green light illumination device, and the blue light illumination device are the same, only the red light illumination device will be described, and the green light illumination device and the blue light illumination device will be described. Is omitted.

As shown in FIG. 7, the red light illumination device 70 in the present embodiment includes an LED light source 71, and the LED light source 71 includes a plurality of sets of LED elements (light sources) 72, lenses 26, and conversion units 73.
A plurality of LED elements 72 are arranged in an array, and are configured to emit red light, which is non-polarized light, toward the lens 26 from its emission end.
The conversion unit 73 includes a rod lens 74 that guides the light emitted from the lens 26, a polarizing plate 75 that transmits polarized light having one polarization direction among the light emitted from the rod lens 74, and light through the polarizing plate 75. An actuator (driving means) 76 that rotates about the axis of the axis and a quarter wavelength plate 77 disposed between the rod lens 74 and the polarizing plate 75 are provided.
The rod lens 74 is provided with a reflective film 74A having an opening in a region where the red light collected by the lens 26 is incident on the incident surface.
The polarizing plate 75 is a wire grid type polarizing plate in which wires (thin wires) made of a metal such as aluminum are formed in a stripe shape on a substrate such as glass. The polarizing plate 75 transmits polarized light having a polarization direction substantially orthogonal to the extending direction of the wire, and reflects polarized light having a polarization direction substantially orthogonal to the polarization direction.
The actuator 76 is configured by, for example, an ultrasonic motor, and is configured to rotate the polarizing plate 75 around the optical axis at a frequency of 60 Hz, for example.

In the red light illumination device 70 as described above, the red light emitted from the LED element 72 enters the rod lens 74 as described above. Then, the red light emitted from the rod lens 74 is converted into polarized light having one polarization direction by the polarizing plate 75 and emitted, and uniformly irradiates the entire image display region of the mirror device 18.
At this time, the polarizing plate 75 is periodically rotated about the optical axis by the actuator 76. As a result, the polarization direction of the light emitted from the polarizing plate 75 changes periodically. Therefore, the polarization direction of the red light with respect to the screen 3 changes periodically.
Here, polarized light having another polarization direction that does not pass through the polarizing plate 75 is reflected by the polarizing plate 75. Then, the reflected light from the polarizing plate 75 is rotated by the ¼ wavelength plate 77 by the ¼ wavelength, and is incident on the rod lens 74 again. Thereafter, the light is reflected by the reflective film 74 </ b> A provided on the rod lens 74 and then enters the polarizing plate 75 again.

As described above, the red light illumination device 70 according to this embodiment and the rear projector including the same also have the same operations and effects as those of the first to third embodiments described above.
Here, since the polarized light having another polarization direction reflected by the polarizing plate 75 is reflected by the reflective film 74A and re-enters the polarizing plate 75, the light emitted from the LED light source 71 can be reused, and the light is used. Efficiency is improved.

[Fifth Embodiment]
Next, a fifth embodiment of a lighting device and a projector according to the present invention will be described with reference to the drawings. Here, FIG. 8 is a schematic perspective view showing the LED light source. In this embodiment, since the configuration of the LED light source is different from that of the fourth embodiment, this point will be mainly described, and the same reference numerals are given to the components described in the above embodiment, and the description thereof will be omitted. To do. Also in this embodiment, since the configurations of the red light illumination device, the green light illumination device, and the blue light illumination device are the same, only the red light illumination device will be described, and the green light illumination device and the blue light illumination device will be described. Is omitted.

As shown in FIG. 8, the red light illumination device 80 in the present embodiment includes a polarizing plate 83 in which the conversion unit 82 of the LED light source 81 is an atypical polarizing plate, and the polarizing plate 83 periodically in a direction perpendicular to the optical axis. And an actuator 84 for moving the actuator.
As described above, the polarizing plate 83 is an atypical polarizing plate in which a wire is formed on a substrate such as glass so as to form a plurality of substantially concentric arcs in a direction perpendicular to the optical axis. It is possible to change the polarization direction of the transmitted polarized light by moving to.
The actuator 84 is configured to move the polarizing plate 83 in a direction perpendicular to the optical axis at a period of 60 Hz, for example.

  As described above, the red light illumination device 80 and the rear projector including the same in the present embodiment also have the same operations and effects as those of the fourth embodiment described above.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the first and second embodiments, the light guide member is composed of a combination of a dove prism and a reflection mirror, but the angle formed between the polarization direction of polarized light incident on the reflection surface and the reflection surface is determined. Other configurations may be used as long as they can be changed with time.
Further, in the third embodiment, the polarization maintaining fiber is used. However, as long as the light can be guided while maintaining the changed state of the light emitted from the laser element and has flexibility, the other It may be a light guide member.
In the fourth and fifth embodiments, the rod lens is used as the light guide member. However, it is only necessary to be able to guide the non-polarized light emitted from the LED element, and other light guides such as other mode optical fibers may be used. It may be an optical member. Further, although the reflective film is provided on the incident surface of the rod lens, the reflective film may not be provided as long as the reflected light reflected by the polarizing plate can be reflected again by the LED element and re-entered on the rod lens. Further, as the polarizing plate, an absorption-type polarizing plate may be used. In this case, the light emitted from the LED element may be directly incident on the polarizing plate without providing a light guide member such as a rod lens.

In addition, the polarization direction of the incident light to the mirror device is periodically changed by the actuator at a frequency of 60 Hz, but if the interference fringe pattern becomes invisible due to the afterimage characteristics of the viewer's eyes, the other frequencies may be used. Alternatively, a configuration that does not change periodically may be used.
And although the dove prism, the reflective mirror, the optical fiber, and the polarizing plate are driven by the actuator, these may be driven by other members.

In addition, the laser light source and the LED light source include a plurality of sets of light emitting elements and conversion units arranged in an array. However, the light source is not limited to a configuration in which one conversion unit is provided for one light emitting element, and a plurality of light emitting elements are provided. It is good also as a structure which provides one conversion part with respect to an element. Further, the laser light source and the LED light source include a plurality of light emitting elements arranged in an array, but may have a configuration having only one light emitting element.
And although the laser element and the LED element are used as a light emitting element, you may use another light emitting element.

In addition, the optical fuse is made of a material that is non-transparent to a light amount exceeding a predetermined value. However, if light irradiation to the mirror device is prevented when the light amount exceeds a predetermined value, other light fuses may be used. It may be a configuration.
Three laser light sources and LED light sources are arranged close to each other and connected to the same cooling unit, but may be connected to different cooling units.

Further, although the mirror device is used as the light modulation means, other light modulation means may be used as long as the light modulation state does not change depending on the polarization direction of the polarized light incident on the light modulation means.
A single-plate projection optical system that modulates light emitted from each illumination device using one mirror device, but a three-plate projection optical system in which three mirror devices corresponding to each illumination device are arranged. It may be a system.
Further, the projector is not limited to the rear projector, and other projectors such as a front projection type projector that has a projection optical system and projects the projection light from the projection optical system onto a screen separately provided to observe the reflected light. It may be.

It is the schematic perspective view and sectional drawing which show the rear projector of 1st Embodiment. It is a schematic block diagram which shows the projection optical system of FIG. It is a schematic perspective view which shows the laser light source of FIG. It is explanatory drawing explaining the drive state by an actuator. It is a schematic perspective view which shows the laser light source of the illuminating device in 2nd Embodiment. It is a schematic perspective view which shows the laser light source of the illuminating device in 3rd Embodiment. It is a schematic perspective view which shows the LED light source of the illuminating device in 4th Embodiment. It is a schematic perspective view which shows the LED light source of the illuminating device in 5th Embodiment. It is explanatory drawing which shows the principle of scintillation.

Explanation of symbols

1 Rear projector (projector), 3 screen (projected member), 15A, 50, 60, 70, 80 Red light illumination device (illumination device), 15B Green light illumination device (illumination device), 15C Blue light illumination device (illumination) Device), 18 mirror device (irradiated member, light modulation means), 25 laser element (light source), 27, 52, 62, 73, 82 conversion unit, 31 dove prism (light guide member), 31a incident surface, 31b exit Surface, 31c, 54a Reflective surface, 32, 57, 64, 76, 84 Actuator (drive means), 35 Optical fuse, 36 Cooling unit, 53a Reflective surface (incident surface), 55 Reflective mirror (exit surface), 56 Light guide Member, 72 LED element (light source), 74 rod lens (light guide member), 74A reflective film, 75 polarizing plate (polarizing member), 83 polarizing plate (polarizing member) Optical member)

Claims (5)

A light source that emits polarized light;
A conversion unit that converts the light emitted from the light source into polarized light whose polarization direction changes with time and guides it to the irradiated surface of the irradiated member;
The conversion unit includes a light guide member that guides light emitted from the light source, and a driving unit that drives the light guide member around the axis of the optical axis,
The light guide member includes an incident surface on which light emitted from the light source is incident, an emission surface that emits light, and a reflective surface that reflects the light incident from the incident surface toward the emission surface. A lighting device characterized by comprising: A light source that emits polarized light;
A conversion unit that converts the light emitted from the light source into polarized light whose polarization direction changes with time and guides it to the irradiated surface of the irradiated member;
The conversion unit includes a light guide member that guides light emitted from the light source, and a driving unit that drives the light guide member around the axis of the optical axis,
The light guide member has flexibility and can guide light while maintaining a polarization state of polarized light emitted from the light source,
The illuminating device characterized in that the driving means drives the exit surface of the light guide member around the optical axis of the light guide member with respect to the incident surface. The lighting device according to claim 1 or 2, characterized in that it comprises an optical fuse for blocking light incident on the surface to be illuminated when the amount of light emitted from the light source exceeds a predetermined value. The lighting device according to any one of claims 1 to 3 ,
Light modulation means for modulating light emitted from the illumination device according to an image signal,
A projector that projects light modulated by the light modulation means onto a projection target member. A plurality of the lighting devices;
The projector according to claim 4 , wherein the plurality of light sources are connected to the same cooling unit.

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