JP2016184064A - Despeckle illumination device, despeckle illumination method, and projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a despeckle illumination device with the high despeckle effect without deteriorating the image quality, a despeckle illumination method, and a projection type display device.SOLUTION: A projection type display device includes: an image formation unit that forms an image with a laser beam emitted from a laser light source; an integrator provided between the laser light source and the image formation unit; a plurality of despeckle wheels, one or more of which is provided between the integrator and the image formation unit and one or more of which is provided rotatably between the integrator and the laser light source; and a control device that controls the rotation of the plurality of despeckle wheels. Each of the plurality of despeckle wheels includes a despeckle region where a despeckle element with the despeckle effect is formed, and a transmission region that transmits light. The control device controls the rotation of the plurality of despeckle wheels so that only one despeckle region of the plurality of despeckle wheels exists on the optical path of the laser beam.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a projection display device using a laser light source.

In a projection display device that uses a laser light source, an image called a speckle pattern is formed on the screen because of the coherent nature of the laser light, so that the projected image is displayed with a reduced image quality with a noticeable glare. It was broken. Several despeckle techniques have been proposed as a method for improving image quality degradation due to speckle. One is a method of creating a despeckle effect by spatially forming and overlapping a plurality of speckle patterns. The other is a method of creating a despeckle effect by temporally forming and overlapping a plurality of speckle patterns. There is also a method of combining a method of creating a spatial despeckle effect and a method of creating a temporal despeckle effect.
As a method of creating a spatial despeckle effect, a diffraction grating is used and a pseudo light source image of a laser light source is increased to form a plurality of speckle patterns. There is a method of forming a plurality of speckle patterns by increasing a light source image.

As a method of creating a temporal despeckle effect, there is a method of forming a speckle pattern that is temporally different by reflecting a light source image on a scanning mirror or a polygon drum and scanning the light source image.
Patent Document 1 (Japanese Patent Laid-Open No. 2012-194268) discloses a diffusion plate in which a first diffusion layer and a second diffusion layer are provided on the front and back surfaces (see FIG. 3). By rotating the diffusion plate, the laser beam passing through the diffusion plate passes only through the first diffusion layer, passes through only the second diffusion layer, and passes through the first and second diffusion layers. In this state, the spot diameters of the laser beams that have passed through the diffusion plate are different from each other, and the despeckle effect is produced.
The laser light after passing through the diffusion plate is converted into uniform and linearly polarized light by passing through the polarization conversion integrator rod, and used as illumination light for the liquid crystal light modulation element.

JP 2012-194268 A

In the technique disclosed in Patent Document 1 described above, the laser light passing through the diffusion plate passes only through the first diffusion layer, passes through only the second diffusion layer, and passes through the first and second diffusion layers. One of the three states. When passing through the diffusion plate, the brightness of the passing light decreases. The degree of decrease in brightness varies depending on the structure (type) of the diffusion plate, but the technology disclosed in the patent document has a state of passing through the first and second diffusion layers. In this case, the decrease in luminance due to the passage through the first diffusion plate and the decrease in luminance due to the passage through the second diffusion layer are added, so that only the first diffusion plate passes, or the second Compared with the state of passing through only the diffusion plate, the luminance is reduced, and there is a possibility that a new problem of deterioration in image quality due to a change in luminance may occur.
Further, in the technique disclosed in Patent Document 1, a diffuser plate is used as a despeckle element that exhibits a despeckle effect, and laser light after passing through the diffuser plate is incident on a polarization conversion integrator rod that is one form of an integrator. It is configured.

The speckle pattern projected on the projection screen differs depending on the arrangement of the same despeckle element. A pseudo light source image is formed near the entrance end of the integrator, whereas illumination light whose distribution is made uniform by the integrator is emitted near the integrator exit end. Of course, the speckle pattern projected on the projection screen is different between the case where the despeckle element is provided near the entrance end and the case where the despeckle element is provided near the exit end.
In the technique disclosed in Patent Document 1, since the despeckle element is provided in the vicinity of the incident end of the integrator, the speckle pattern projected on the projection screen and the despeckle effect thereby are limited.
It is an object of the present invention to realize a despeckle illumination device, a despeckle illumination method, and a projection display device that have a large despeckle effect without causing deterioration in image quality.

The projection display device according to the present invention is
A laser light source;
An image forming unit that forms an image using laser light emitted from the laser light source;
An integrator provided between the laser light source and the image forming unit;
One or more provided between the integrator and the image forming unit, and one or more rotatable despeckle wheels provided between the integrator and the laser light source;
A control device for controlling rotation of the plurality of despeckle wheels,
Each of the plurality of despeckle wheels includes a despeckle region in which a despeckle element having a despeckle effect is formed, and a transmission region that transmits light, and the control device includes one of the plurality of despeckle wheels. The rotation of the plurality of despeckle wheels is controlled so that only the region exists on the optical path of the laser beam.
A despeckle illumination device according to the present invention is a despeckle illumination device that supplies illumination light for forming an image to an image forming unit,
A laser light source;
An integrator provided between the laser light source and the image forming unit;
One or more provided between the integrator and the image forming unit, and one or more rotatable despeckle wheels provided between the integrator and the laser light source;
A control device for controlling rotation of the plurality of despeckle wheels,
Each of the plurality of despeckle wheels includes a despeckle region in which a despeckle element having a despeckle effect is formed, and a transmission region that transmits light, and the control device includes one of the plurality of despeckle wheels. The rotation of the plurality of despeckle wheels is controlled so that only the region exists on the optical path of the laser beam.
The despeckle lighting method according to the present invention is:
A despeckle illumination method for supplying illumination light for forming an image to an image forming unit,
An integrator is provided between the laser light source and the image forming unit,
One or more rotatable despeckle wheels each including a despeckle region in which a despeckle element having a despeckle effect is formed and a transmission region that transmits light are provided between the integrator and the image forming unit, and the integrator And at least one between the laser light source and
The rotation of the plurality of despeckle wheels is controlled such that only one of the plurality of despeckle wheels is present on the optical path of the laser beam.

  In the present invention, a despeckle illumination device, a despeckle illumination method, and a projection display device having a large despeckle effect can be realized without causing a deterioration in image quality.

It is a schematic diagram which shows the structure of one Embodiment of the projection type display apparatus provided with the despeckle illumination apparatus by this invention. It is a top view which shows the structure of the despeckle wheel 113,114 in FIG. It is a schematic diagram which shows the structure of other embodiment of the projection type display apparatus provided with the despeckle illumination apparatus by this invention.

Next, an embodiment according to the present invention will be described.
FIG. 1 is a schematic diagram showing a configuration of an embodiment of a projection display device provided with a despeckle illumination device according to the present invention.
In the present embodiment, the first laser light source 1 ₁ , the second laser light source 1 ₂ , the third laser light source 1 ₃ , the collimator lenses 2 ₁ to 2 ₃ , the condenser lens 3, the first dichroic mirror 4, Two dichroic mirror 5, reflection mirror 6, integrator 7, illumination system lenses 8 ₁ and 8 ₂ , illumination mirror 9, DMD (Digital Mirror Device) 10 ₁ to 10 ₃ , Philips prism 11, projection lens 12, despeckle wheel 113, 114 and the control device 115.
The first laser light source 1 ₁ , the second laser light source 1 ₂ , and the third laser light source 1 ₃ output the first laser light, the second laser light, and the third laser light having different wavelengths, respectively. The output lights are collimated through collimator lenses 2 ₁ to 2 ₃ provided corresponding to the laser light sources, and enter the first dichroic mirror 4, the second dichroic mirror 5, and the reflection mirror 6.

The first dichroic mirror 4 has a characteristic of reflecting the first laser beam and transmitting the second laser beam and the third laser beam. The second dichroic mirror 5 has a characteristic of reflecting the second laser beam and transmitting the third laser beam. The reflection mirror 6 has a characteristic of reflecting the third laser beam.
The first laser beam, the second laser beam, and the third laser beam synthesized on the same optical axis by the first dichroic mirror 4, the second dichroic mirror 5, and the reflection mirror 6 are integrated into the integrator 7 by the condenser lens 3. It is condensed on the incident surface.
The light incident on the integrator 7 reaches the exit surface of the integrator 7 while being totally reflected by the side surface of the integrator 7, so that the brightness distribution of the emitted light is made uniform. The light emitted from the integrator 7 enters the Philips prism 11 through the illumination system lens 8 ₁ , the illumination mirror 9, and the illumination system lens 8 ₂ . Incident light is the Philips prism 11, the first laser beam of a wavelength of light, the second laser beam of a wavelength of light, is separated into light of the third laser light wavelength of each DMD 10 ₁ to 10 ₃ Irradiated. The DMDs 10 ₁ to 10 ₃ form image light corresponding to each irradiation color by reflecting each irradiation light, and each reflection light is synthesized by the Philips prism 11 and projected through the projection lens 12 such as a screen. Projected onto the screen.

The illumination mirror 9 provided between the illumination system lenses 8 ₁ and 8 ₂ is arranged to make the structure compact. The illumination mirror 9 serves to bend the optical path by reflecting light. Philips prism 11 constitute an image forming unit together with the DMD 10 ₁ to 10 _3, in accordance with the deflection angle of the DMD 10 ₁ to 10 _3, light is incident obliquely to the DMD 10 ₁ to 10 _3, the image light by reflecting DMD 10 The light is emitted in the direction perpendicular to the reflection surfaces ₁ to 10 ₃ . The control device 115 controls the DMDs 10 ₁ to 10 ₃ in accordance with the input video signal S and modulates the three colors of image light, thereby projecting image light indicating a color image.
In the present embodiment, the speckle pattern on the projection screen is relaxed by disposing the rotating foil type despeckle wheels 113 and 114 on the incident side and the emission side of the integrator 7. As shown in FIG. 2, in the despeckle wheels 113 and 114, the half area of the disk is made into despeckle areas 113 ₁ and 114 ₁ in which a diffraction grating as a despeckle element is formed, and the remaining half area is a flat glass. The transmission regions 113 ₂ and 114 ₂ are formed of a substrate and transmit light.
The control device 115 controls the rotational operation of the despeckle wheels 113 and 114 in addition to the above-described modulation control of the DMDs 10 ₁ to 10 _3. The combined light emitted from the condenser lens 3 is despeckle regions 113 ₁ and 114 _1. The despeckle wheels 113 and 114 are rotated so that only one of them passes.

Even if the same despeckle element is used, the speckle pattern projected on the projection screen is different depending on the arrangement. While a pseudo light source image is formed in the vicinity of the incident side of the integrator, the distribution of illumination light is made uniform by the integrator and irradiated in the vicinity of the output side of the integrator. Therefore, when a diffraction grating is used as a despeckle element as in the present embodiment, if the despeckle element is arranged on the incident side of the integrator, a plurality of pseudo light source images are formed, and a different speckle pattern is generated for each light source image. It is formed. For this reason, the despeckle effect by the difference in a speckle pattern generate | occur | produces. On the other hand, when the despeckle element is arranged on the output side of the integrator, the illumination light to the DMD is irradiated a plurality of times while slightly shifting the region, and a plurality of speckle patterns are also formed. At this time, the despeckle effect varies depending on the difference in light irradiation to the DMD.
The projection display apparatus according to the present embodiment has the above-described configuration, and thus displays speckle patterns that are temporally different on the projection screen. For this reason, the despeckle effect is high. In addition, since the illumination light is configured to pass through only one of the despeckle elements arranged on the incident side and the emission side of the integrator, the change in the brightness of the projection light is small.

In this embodiment, a diffraction grating is used as a despeckle element formed in the despeckle regions 113 ₁ and 114 ₁ . As the despeckle element, a diffusion plate or a phase difference plate can be used in addition to the diffraction grating. Moreover, these can also be combined and it is good also as such a structure.
Further, although the despeckle wheel 113 arranged on the incident side of the integrator 7 is provided between the condenser lens 3 and the integrator 7, the arrangement shown in FIG. In the example shown in FIG. 3, a despeckle wheel 102 is provided at the emission part of each laser light source 1 ₁ to 1 ₃ (see FIG. 1), and the emission part of each collimator lens 2 ₁ to 2 ₃ (see FIG. 1). A despeckle wheel 103 is provided. Similar to the despeckle wheels 113 and 114 shown in FIG. 2, the despeckle wheels 102 and 103 include a despeckle region where a despeckle element is formed and a transmission region.

The despeckle wheel 114 shown in FIG. 1 is provided, and at least one of the despeckle wheels 102, 103, and 113 shown in FIG. 3 is provided. In this case, the despeckle wheel 102, 103, 113, 114 has a despeckle area and a transmission area different from those shown in FIG. The control device 115 controls the rotation of each despeckle wheel 102, 103, 113, 114 so that only one despeckle region of the provided despeckle wheel exists on the optical path of the laser light from the laser light source. .
A plurality of despeckle wheels may be provided between the exit side of the integrator 7 and the image forming unit. For example, it may be provided between the illumination system lens 8 ₁ and the illumination mirror 9 and between the illumination mirror 9 and the illumination system lens 8 ₂ .
Even when a plurality of despeckle wheels are provided between the laser light source and the integrator 7 and between the integrator 7 and the image forming unit as described above, the control device 115 is on the optical path of the laser light from the laser light source. By controlling each despeckle wheel so that there is only one despeckle area, it is possible to suppress the reduction in brightness due to the despeckle element. It is possible to provide a projection display device with high image quality and low image quality.

Incidentally, in the embodiment described above, for example, the first through third laser light source 1 ₁ to 1 ₃ to output the result of red, blue, and green laser light, DMD 10 ₁ to 10 ₃ are red, blue, A green image is formed. Although it has been described that a laser light source is used as the light source, it is also possible to use fluorescence partially generated by a phosphor as in the invention described in Patent Document 1. Further, an LCOS (Liquid crystal on silicon) or a transmissive liquid crystal light valve can be used as the image element, and such a configuration may be used.
In addition, as a despeckle element, a diffraction grating, a diffusion plate, and a phase difference plate have been described as examples. However, these may be used in combination.

1 ₁ 1st laser light source 1 ₂ 2nd laser light source 1 ₃ 3rd laser light source 2 ₁ to 2 ₃ Collimator lens 3 Condensing lens 4 1st dichroic mirror 5 2nd dichroic mirror 6 Reflecting mirror 7 Integrator 8 ₁ , 8 ₂ Illumination system lens 9 Illumination mirror 10 ₁ to 10 ₃ DMD
11 Philips prism 12 Projection lens 113, 114 Despeckle wheel 115 Control device

Claims (9)

A laser light source;
An image forming unit that forms an image using laser light emitted from the laser light source;
An integrator provided between the laser light source and the image forming unit;
One or more provided between the integrator and the image forming unit, and one or more rotatable despeckle wheels provided between the integrator and the laser light source;
A control device for controlling rotation of the plurality of despeckle wheels,
Each of the plurality of despeckle wheels includes a despeckle region in which a despeckle element having a despeckle effect is formed, and a transmission region that transmits light, and the control device includes one of the plurality of despeckle wheels. A projection display device that controls rotation of the plurality of despeckle wheels so that only a region exists on an optical path of the laser light. The projection display device according to claim 1,
A projection display device in which a despeckle element formed on each of the plurality of despeckle wheels is one of a diffraction grating, a diffusion plate, a retardation plate, or a combination thereof. The projection display device according to claim 1 or 2,
A projection display device in which the image forming unit includes a DMD. The projection display device according to claim 1 or 2,
A projection display device in which the image forming unit includes a transmissive liquid crystal light valve. The projection display device according to claim 1 or 2,
A projection display device in which the image forming unit includes LCOS. A despeckle illumination device that supplies illumination light for forming an image to an image forming unit,
A laser light source;
An integrator provided between the laser light source and the image forming unit;
One or more provided between the integrator and the image forming unit, and one or more rotatable despeckle wheels provided between the integrator and the laser light source;
A control device for controlling rotation of the plurality of despeckle wheels,
Each of the plurality of despeckle wheels includes a despeckle region in which a despeckle element having a despeckle effect is formed, and a transmission region that transmits light, and the control device includes one of the plurality of despeckle wheels. A despeckle illumination device that controls rotation of the plurality of despeckle wheels so that only a region exists on an optical path of the laser beam. In the despeckle lighting device according to claim 6,
A despeckle illumination device in which a despeckle element formed on each of the plurality of despeckle wheels is one of a diffraction grating, a diffusion plate, a retardation plate, or a combination thereof. A despeckle illumination method for supplying illumination light for forming an image to an image forming unit,
An integrator is provided between the laser light source and the image forming unit,
One or more rotatable despeckle wheels each including a despeckle region in which a despeckle element having a despeckle effect is formed and a transmission region that transmits light are provided between the integrator and the image forming unit, and the integrator And at least one between the laser light source and
A despeckle illumination method for controlling rotation of the plurality of despeckle wheels so that only one despeckle region of the plurality of despeckle wheels exists on the optical path of the laser beam. The despeckle lighting method according to claim 8,
A despeckle illumination method, wherein a despeckle element formed on each of the plurality of despeckle wheels is any one of a diffraction grating, a diffusion plate, a retardation plate, or a combination thereof.

Images