JP2008262029A - Illuminator and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminator capable of suppressing speckle noise, having high efficiency of using light and achieving the reduction of a cost, and a projector. <P>SOLUTION: The illuminator 1 generating illuminating light for illuminating an object illumination area on a predetermined surface to be irradiated includes: a light source 2 which emits light; a variable focus lens 3 on which the light emitted from the light source 2 is made incident and which can change a focal position; a superposing illumination element 4 which superposes the light emitted from the variable focus lens 3 so as to illuminate the object illumination area S; and a control part which performs control so that the focal position of the variable focus lens 3 is temporally changed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

In recent projection type image display apparatuses, a discharge lamp such as an ultrahigh pressure mercury lamp is generally used as a light source. However, such a discharge lamp has problems such as a relatively short life, difficulty in instantaneous lighting, a narrow color reproduction range, and ultraviolet light emitted from the lamp may deteriorate the liquid crystal light bulb. In order to solve this problem, a projection type image display apparatus using a laser light source that emits monochromatic light instead of a discharge lamp has been proposed (see, for example, Patent Document 1).
The laser display device described in Patent Document 1 includes red, green, and blue semiconductor lasers, a plurality of collimator lenses that collimate laser light emitted from the semiconductor lasers, and light that is collimated by the collimator lenses. And a spatial light modulator that modulates the light emitted from each microlens. The light that has passed through each spatial light modulator is combined by a dichroic mirror and displayed on a screen by a projector lens. In this laser display device, the microlens can be rotated with the optical axis as a rotation axis, and by rotating the microlens, speckle noise of the laser light that irradiates the spatial light modulator is reduced or eliminated. It has become.

Further, as a method for reducing speckle noise, a method using a diffusion plate has been proposed (see, for example, Patent Document 2).
In the exposure illumination apparatus described in Patent Document 2, a diffusion plate having a random uneven surface such as a rubbed glass is inserted between an illumination light source and a surface to be illuminated. Then, by rotating the diffuser plate, the speckle pattern generated on the image plane is temporally changed, and the speckle pattern is averaged by the integration effect within the response speed of the light receiving system.
Japanese Patent Laid-Open No. 11-64789 JP 7-297111 A

However, in the laser display device described in Patent Document 1, since the microlens is rotated in order to reduce speckles, mechanical parts such as a rotational drive system are required, and the cost is increased.
Further, in the technique described in Patent Document 2, since the incident light is diffused by rotating the diffusion plate, a loss occurs in the light incident on the optical system arranged at the subsequent stage of the diffusion plate.

  The present invention has been made to solve the above-described problems, and provides an illumination device and a projector that can suppress speckle noise, have high light utilization efficiency, and can reduce costs. With the goal.

In order to achieve the above object, the present invention provides the following means.
An illuminating device of the present invention is an illuminating device that generates illumination light for illuminating a target illumination area on a predetermined irradiated surface, and a light source that emits light, and light emitted from the light source is incident and focused A variable focus lens whose position can be changed, a superimposing illumination element that superimposes light emitted from the variable focus lens and illuminates the target illumination area, and a focal position of the variable focus lens changes with time. And a control unit for controlling.

In the illuminating device according to the present invention, the light emitted from the light source enters the variable focus lens. And the light which injected into the variable focus lens is inject | emitted as illumination light which illuminates a superimposition illumination element, and illuminates the target illumination area | region of a to-be-irradiated surface.
At this time, since the focal position of the variable focus lens is temporally changed by the control unit, the beam diameter of the light emitted from the variable focus lens changes. That is, the irradiation area of the light emitted from the variable focus lens and illuminating the superimposed illumination element changes. Thereby, since the speckle pattern of the light emitted from the superimposed illumination element changes with time, the light is integrated with time by the afterimage effect of the human eye and speckle noise is suppressed. That is, the illumination device of the present invention does not include a diffuser plate as in the prior art, but changes the focal position of the variable focus lens with time, thereby changing the speckle pattern of light emitted from the superimposed illumination element. It changes with time. As a result, it is possible to reduce the occurrence of speckle noise in the light illuminated on the target illumination area without reducing the light utilization efficiency.
Furthermore, compared to the conventional optical system that rotates the diffusion plate, the existing optical element that emits the light emitted from the light source to the superimposed illumination element is a variable focus lens, so the number of components is not increased. It is possible to reduce the cost.
In addition, since the surface to be illuminated is illuminated by the light superimposed by the superimposing illumination element, the target illumination area is made uniform even if the focal position of the variable focus lens changes and the illumination area of the light incident on the superimposing illumination element changes. It can be illuminated.
Note that the change in the focal position includes a change in focal length along the optical axis of the variable focus lens and a change in focal length shifted from the optical axis.

  Moreover, it is preferable that the illuminating device of this invention is provided with the light source moving means which arrange | positions the said light source so that a movement is possible, and moves the said light source according to the change of the focus position of the said variable focus lens.

  In the illumination device according to the present invention, the light source is moved by the light source moving means in accordance with the change in the focal position of the variable focus lens. As described above, in addition to the change in the focal position of the variable focus lens, the irradiation area on the superimposed illumination element of the light emitted from the variable focus lens changes more by moving the light source. Therefore, it is possible to more effectively reduce the occurrence of speckle noise in the light illuminated in the target illumination area.

  In the illumination device of the present invention, it is preferable that the light source moving unit moves the light source so that the light source is positioned at a focal position of the variable focus lens.

  In the illuminating device according to the present invention, the light source moving means moves the light source so as to place the light source at the focal position of the variable focus lens, so that parallel light is incident on the superimposed illumination element. Thereby, the conversion efficiency of the light inject | emitted from a superimposition illumination element can be improved.

  In the illumination device of the present invention, it is preferable that the light source moving unit moves the light source during a time when the focal position of the variable focus lens does not change.

  In the illumination device according to the present invention, the light source moving means moves the light source during the time when the focal position of the variable focus lens does not change. Thereby, since there is no time during which the beam diameter of the light that illuminates the superimposed illumination element does not change, the illumination area that illuminates the target illumination area always changes. Therefore, speckle noise can be reduced in the light emitted from the superimposed illumination element. Thereby, it becomes possible to irradiate the target illumination area with uniform illumination light that more reliably suppresses the generation of speckle noise without lowering the light utilization efficiency.

  In the illumination device of the present invention, a plurality of the light sources and the variable focus lenses are provided, the variable focus lenses are provided corresponding to the plurality of light sources, and the control unit controls the plurality of variable focus lenses. Among these, it is preferable to control so that the focal position of at least one of the variable focus lenses is constantly changed.

In the illumination device according to the present invention, the control unit controls the focal position of at least one variable focus lens among the plurality of variable focus lenses so as to constantly change. That is, since a variable focus lens is provided corresponding to each of the plurality of light sources, the light emitted from the superimposed illumination element can be changed by simply changing the focal position of the plurality of variable focus lenses without moving the light source. The generation of speckle noise can be reduced. Thereby, it becomes possible to irradiate the target illumination area with uniform illumination light that more reliably suppresses the generation of speckle noise without lowering the light utilization efficiency.
Furthermore, by moving the light source in addition to the change in the focal position of the variable focus lens, more speckle patterns are emitted from the superimposed illumination element. Therefore, speckle noise can be suppressed more effectively.

  Further, in the illumination device of the present invention, the variable focus lens applies an electric voltage to the oil droplet filled in the container, an electrolytic solution that covers the oil droplet and has a refractive index different from that of the oil droplet, and the electrolytic solution. It is preferable that the curvature of the oil droplet is changed by controlling the voltage applied to the electrode.

  In the illumination device according to the present invention, the interface shape between the electrolytic solution and the oil droplet is changed by the control unit. Thereby, since the curvature of the oil droplet changes with time, the focal position also changes with this change. Therefore, since the response speed of the oil droplets and the electrolytic solution is fast, the focal positions of the plurality of variable focus lenses can be adjusted at high speed.

In the illumination device of the present invention, the variable focus lens includes a first substrate on which a circular center electrode and a plurality of concentric annular electrodes having different radii are formed, and a common electrode formed on one surface. Two substrates, and a liquid crystal provided between the first substrate and the second substrate,
It is preferable that the control unit controls the alignment state of the liquid crystal by controlling a voltage applied to the center electrode, the annular electrode, and the common electrode.

  In the illuminating device according to the present invention, the control unit controls the alignment state of the liquid crystal between the center electrode, the annular electrode, and the common electrode, whereby the optical distance between the central electrode, the annular electrode, and the common electrode. Changes. Thereby, the focal position changes with time. Therefore, since it can be manufactured in the same process as the manufacturing method of a normal liquid crystal panel, the manufacturing cost of the lighting device can be suppressed.

  In the illumination device according to the present invention, the variable focus lens includes a plurality of lenses, and the control unit moves at least one of the plurality of lenses, whereby the variable focus lens is It is preferable to change the focal position.

  In the illumination device according to the present invention, the control unit changes the focal position of the variable focus lens by moving at least one of the plurality of lenses. That is, the focal position can be changed by combining a plurality of commonly used lenses. Therefore, since it is only necessary to change the physical positions of the plurality of lenses, the plurality of lenses can be easily designed.

  A projector according to the present invention includes the above-described illumination device, a light modulation device that modulates light emitted from the illumination device according to an image signal, and a projection device that projects an image formed by the light modulation device. It is characterized by that.

  In the projector according to the present invention, the light emitted from the illumination device enters the light modulation device. Then, the image formed by the light modulation device is projected by the projection device. At this time, as described above, the light emitted from the lighting device is light in which speckle noise is suppressed without lowering the light use efficiency, so that an image with reduced glare (scintillation) can be obtained. It becomes possible to irradiate the projection surface.

  In the projector according to the aspect of the invention, it is preferable that the control unit changes the focal position of the variable focus lens so that the blanking period of the modulation device is a time during which the focal position of the variable focus lens does not change. .

  In the projector according to the present invention, the blanking period (the time from the completion of writing of one frame to the start of writing of the next frame (vertical blanking period), or the scanning line displayed from the left to the right Since the time for returning to the left again (horizontal blanking period) is when no light is incident on the light modulation device, the variable focus is set so that the focus position of the variable focus lens does not change. Controls the timing of changing the focal position of the lens. Therefore, since the focal position always changes while the image is being formed, speckle noise can be proposed for the light emitted from the superimposed illumination element, and thus an image with reduced occurrence of scintillation is projected. It becomes possible.

  In the projector according to the aspect of the invention, the illumination device may include a plurality of the light sources that emit light of different wavelengths, and the variable focus lens provided corresponding to each of the plurality of light sources, and the light modulation. The plurality of light beams having different wavelengths are sequentially incident on the apparatus, and the control unit is configured to determine a focal position of the variable focus lens corresponding to the light source that emits light that is not incident on the light modulation apparatus. It is preferable to change the focal position of the variable focus lens so that the time does not change.

  In the projector according to the present invention, the control unit is configured so that the time during which the light is not incident on the light modulation device is a time during which the focal position of the variable focus lens corresponding to the light source that emits the light that is not incident does not change. Control the focal position to change. Thereby, for example, the focal position of the variable focus lens corresponding to the light source emitting light projected on the screen changes, and the focal position of the variable focus lens corresponding to the light source emitting light not projected on the screen. Does not change. Therefore, it is possible to efficiently suppress the generation of speckle noise in the light emitted from the superimposed illumination element.

  Hereinafter, embodiments of a lighting device and a projector according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

[First Embodiment]
1st Embodiment of the illuminating device of this invention is described with reference to FIGS.
FIG. 1 is a schematic configuration diagram illustrating an illumination device according to the first embodiment. In FIG. 1, an illuminating device 1 illuminates an irradiation surface 11 of an illumination object 10, and includes a laser light source (light source) 2, a variable focus lens 3, and a hologram element (superimposed illumination element) 4. ing. Further, the entire illumination surface (illuminated surface) 11 of the illumination object 10 is defined as an object illumination region S.

  The laser light source 2 emits laser light L. The laser light source 2 is provided with a moving unit (light source moving means) 15, and the moving unit 15 allows the laser light source 2 to move in the direction of the optical axis O of the hologram element 4. For example, a piezoelectric element is used as the moving unit 15. Further, the optical axis O of the hologram element 4 is an axis that passes through the center of an effective region where a plurality of recesses 4M shown in FIG. 2 to be described later is formed and is perpendicular to the plane on which the plurality of recesses 4M are formed. is there.

The hologram element 4 generates illumination light that irradiates the irradiation surface 11 of the illumination object 10.
The hologram element 4 is formed of a material that can transmit laser light, such as quartz (glass) or transparent synthetic resin. The hologram element 4 of the present embodiment is a computer generated hologram (CGH).

  The diffractive optical element (hologram element) 4 has an illumination area setting function, an illuminance uniformity function, and an enlarged illumination function. The hologram element 4 having the illumination area setting function diffracts incident light and generates illumination light that illuminates the target illumination area S of the irradiation surface 11. Further, the hologram element 4 having an illuminance uniformizing function equalizes the illuminance of at least a part of a predetermined region. Further, as shown in FIG. 1, the hologram element 4 having an enlarged illumination function sets the target illumination area S of the illumination object 10 in an illumination area larger than the emission area where light is emitted from the emission end face 4 b of the hologram element 4. Illuminate.

2A and 2B are schematic diagrams illustrating an example of a diffractive optical element, in which FIG. 2A is a plan view and FIG. 2B is a cross-sectional view taken along line AA in FIG. In FIG. 2, the hologram element 4 includes a plurality of rectangular recesses (uneven structure) 4M on its surface and a frame-shaped holding unit 4H that holds the plurality of recesses 4M and has optical transparency. The recesses 4M have different depths. Further, the laser light emitted from the hologram element 4 illuminates the target illumination region S of the illumination target object 10 by causing the light to enter the concave portion 4M. Here, an area where the plurality of recesses 4M are formed is referred to as an effective area P.
Then, by appropriately adjusting the surface condition of the hologram element 4 including the pitch d between the recesses 4M and the depth (height of the protrusions) t of the recesses 4M, a predetermined function (illumination area setting function, A diffused light generation function and an enlarged illumination function). As a design method for optimizing the surface condition, a predetermined calculation method (simulation method) such as an iterative Fourier method is exemplified.

  Note that the hologram element 4 is not limited to the one having the rectangular recess 4M, and may have a surface in which planes facing different directions are combined. For example, the hologram element 4 may be a so-called blaze type having a triangular recess having a slope. Further, the hologram element 4 may have a region having a rectangular recess 4M as shown in FIG. 2 and a region having a triangular recess. And the hologram element 4 which has a desired function can be formed by optimizing the surface conditions.

The variable focus lens 3 is a liquid lens that changes the focal length (focus position) of the laser light L emitted from the laser light source 2. That is, the liquid lens 3 has a configuration in which the curvature can be changed with time, as shown in FIGS. 3 (a) and 3 (b).
First, a specific configuration of the liquid lens 3 will be described.
The liquid lens 3 includes a sealing member (container) 21 in which a concave portion 21a is formed, a first electrode 22 and a second electrode 23 formed on inner side surfaces 21b and 21c of the concave portion 21a, a first electrode 22 and a second electrode. An oil droplet 24 provided in contact with the electrode 23 and an aqueous electrolyte solution 25 in contact with the first electrode 22 and the second electrode 23 and covering the oil droplet 24 are provided.
A transparent electrode 26 is provided on a surface 21e facing the bottom surface 21d of the recess 21a of the sealing member 21. The first electrode 22, the second electrode 23, and the transparent electrode 26 are formed of an ITO (Indium Tin Oxide) film.
Further, a power source E is connected to the first electrode 22, the second electrode 23 and the transparent electrode 26, and a voltage is applied between the first electrode 22 and the second electrode 23 and the transparent electrode 26. ing. In addition, the power source E is provided with a control unit 20a that temporally changes the voltage applied to the first electrode 22, the second electrode 23, and the transparent electrode 26. Note that the waveform of the voltage applied by the power source E is a sinusoidal waveform.

Next, a method for changing the focal length of the liquid lens 3 will be described.
As shown in FIG. 3A, when a voltage Va is applied between the first electrode 22 and the second electrode 23 and the transparent electrode 26 by the power source E at the time ta, the electrolytic solution 25 is The curvature of the oil droplet 24 is Ra by being drawn into the first and second electrodes 22 and 23.
As shown in FIG. 3B, when a voltage Vb greater than the voltage value Va is applied between the first electrode 22 and the second electrode 23 and the transparent electrode 26 by the power source E at time tb. The curvature of the oil droplet 24 becomes Rb larger than Ra. As described above, when the voltage applied between the first electrode 22 and the second electrode 23 and the transparent electrode 26 is increased, the curvature of the oil droplet 24 increases.
In this embodiment, since the waveform of the voltage applied by the power source E is a sine waveform, the curvature of the oil droplet 24 between time ta and time tb changes smoothly (continuously). Yes.
The response speed of the liquid lens 3 is about 1 kHz. That is, it is possible to switch at a frequency higher than the flicker frequency that can be detected by humans, for example, 30 Hz or more, preferably 60 Hz or more.

Next, the movement of the laser light source 2 in the optical axis O direction will be described.
As shown in FIG. 4A, since the curvature of the oil droplet 24 is Ra at time ta, the focal length of the liquid lens 3 is fa. At this time, the moving unit 15 moves the laser light source 2 to a position where the distance from the liquid lens 3 on the optical axis O is fa. The laser light L emitted from the laser light source 2 becomes parallel light in the liquid lens 3 and is emitted toward the incident end face 4 a of the hologram element 4. The effective area P of the hologram element 4 is illuminated with parallel light having a beam diameter of Sa.

  Further, as shown in FIG. 4B, at time tb, the curvature of the oil droplet 24 is Rb larger than Ra, so that the focal length of the liquid lens 3 becomes fb smaller than fa. At this time, the moving unit 15 moves the laser light source 2 to a position where the distance on the optical axis O from the liquid lens 3 is fb. The laser light L emitted from the laser light source 2 becomes parallel light in the liquid lens 3 and is emitted toward the incident end face 4 a of the hologram element 4. Then, the effective area P of the hologram element 4 is illuminated with parallel light of Sb whose beam diameter is smaller than Sa.

Next, a method of irradiating the target illumination region S of the irradiation surface 11 of the illumination target object 10 using the illumination device 1 of the present embodiment having the above configuration will be described.
The laser light L emitted from the laser light source 2 enters the liquid lens 3 and is converted into parallel light as shown in FIGS. The laser light L converted into parallel light enters the hologram element 4. Then, the laser light L diffracted by the hologram element 4 illuminates the target illumination region S of the irradiation surface 11 of the illumination target object 10 in a superimposed manner.
At this time, since the voltage applied to the liquid lens 3 is changed with time by the control unit 20a, the curvature of the oil droplet 24 changes with time. Then, the moving unit 15 moves the laser light source 2 to the focal position along the optical axis O according to the curvature of the oil droplet 24 of the liquid lens 3.
As a result, the size of the beam diameter of the laser light emitted from the liquid lens 3 changes, so that the illumination area of the effective area P changes. That is, since the illumination area of the laser light L incident on the effective area P of the hologram element 4 changes every moment, accompanying this change, the laser light emitted from the hologram element 4 has a different reproduction pattern. Therefore, it is possible to remove speckle noise of the laser light emitted from the hologram element 4 by superimposing these plurality of reproduction patterns.

In the illuminating device 1 according to the present embodiment, instead of using a diffusing plate that may cause a decrease in light utilization efficiency as in the past, the illumination device 1 is emitted from the hologram element 4 by changing the focal position of the liquid lens 3. It is possible to reduce speckle of light. Therefore, it is possible to illuminate the target illumination area S of the irradiation surface 11 with the laser light from which speckles have been removed without reducing the light utilization efficiency.
Further, since the target illumination area S is illuminated by the light superimposed by the hologram element 4, even if the focal length of the liquid lens 3 changes and the illumination area of the light incident on the hologram element 4 changes, the target illumination area S is changed. It becomes possible to illuminate uniformly.
That is, the lighting device 1 of the present embodiment can suppress speckle noise, have high light utilization efficiency, and can reduce the cost.

Further, since the moving unit 15 moves the laser light source 2 to be disposed at the focal position of the liquid lens 3, parallel light enters the hologram element 4. As a result, the laser light emitted from the hologram element 4 can illuminate the target illumination area S with parallel light, so that the light utilization efficiency can be improved.
Further, since the liquid lens 3 is used as the variable focus lens, the response speed of the oil droplets 24 and the electrolytic solution 25 is fast, so that the focal length can be adjusted at high speed.
Further, compared to the conventional case where a rotational drive system is used, the durability is high and it is possible to manufacture at a low cost.

Although the laser light source 2 is moved by the moving unit 15 so that the laser light source 2 is disposed at the focal position of the liquid lens 3, only the focal length of the liquid lens 3 is changed without moving the laser light source 2. Also good. In this configuration, the existing optical element that emits the laser light L emitted from the laser light source 2 to the hologram element 4 is the liquid lens 3 as compared with the conventional optical system that rotates the diffusion plate. Since the number of points is not increased, the cost can be reduced.
In this configuration, since parallel light is not incident on the hologram element, the light conversion efficiency in the hologram element 4 is slightly reduced. However, the speckle noise of the illumination light that illuminates the target illumination area S can be suppressed only by controlling the liquid lens 3. Is possible.
In addition, the moving unit during the time when the focal position of the liquid lens 3 does not change (when the oil droplet curvature starts to decrease from the largest state or when the oil droplet curvature starts to increase from the smallest state). 15 may move the laser light source 2. In the case of this configuration, there is no time during which the illumination area of the laser light that illuminates the hologram element 4 does not change, so that the beam diameters Sa and Sb of the light that illuminates the target illumination area S always change. Therefore, generation of speckle noise in the light emitted from the hologram element 4 can be reduced. Thereby, it becomes possible to irradiate the target illumination region S with uniform illumination light that more reliably suppresses the generation of speckle noise without reducing the light utilization efficiency.

Further, although the laser light source 2 is movable in the direction of the optical axis O of the hologram element 4, it is not limited to this. That is, the liquid lens 3 applies a voltage only between the first electrode 22 and the transparent electrode 26 by the power source E as shown in FIG. 5A, or as shown in FIG. By applying a voltage only between the second electrode 23 and the transparent electrode 26, it is decentered about the optical axis O, so that the focal position of the liquid lens 3 is focused on other than the optical axis O. In this way, when the voltage applied to the liquid lens 3 is controlled, since the focal position is other than on the optical axis O, the laser light source 2 is moved by the moving unit 15 so that the laser light source 2 is disposed at this focal position. Move it.
Further, although the liquid lens 3 is used as the variable focus lens, a bubble lens including a liquid that can be vaporized by applying a voltage may be used. In the valve lens, when the voltage is applied in the same manner as the liquid lens 3, the curvature of the liquid changes and the focal length changes. Further, the variable focus lens may be a combination of a plurality of lenses. In this case, a piezo actuator that moves at least one of the plurality of lenses is provided. By this piezo actuator, the focal position can be changed by moving at least one of the plurality of lenses. Therefore, since it is only necessary to change the physical positions of the plurality of lenses, the plurality of lenses can be easily designed.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIGS. In each embodiment described below, portions having the same configuration as those of the lighting device 1 according to the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
The illumination device 30 according to the present embodiment is different from the first embodiment in that a liquid crystal lens 31 is used as a variable focus lens. Other configurations are the same as those of the first embodiment.

As shown in FIG. 6, the liquid crystal lens 31 includes a pair of light-transmitting first substrate 32 and second substrate 33, and a sealing material provided between the first substrate 32 and the second substrate 33. The liquid crystal 35 is filled by 34.
A plurality of Fresnel-shaped lens pattern regions Q are formed on the side of the first substrate 32 on which the liquid crystal 35 is provided. In this region Q, as shown in FIG. 7, a circular center electrode 36a and a plurality of concentric ring electrodes 36b having different radii are formed around the center electrode 36a. On the other hand, as shown in FIG. 6, a common electrode 37 is formed on one side of the second substrate 33 on the side where the liquid crystal 35 is provided. The electrodes 36a, 36b, and 37 are made of, for example, ITO (Indium Tin Oxide). As a forming method, an ITO film is formed on the entire surfaces of the substrates 32 and 33 by a vacuum deposition method, a sputtering method, or a CVD method, and then formed into a desired shape by a photolithography method. The center electrode 36a and the annular electrode 36b are electrically connected by a lead electrode (not shown).
As shown in FIG. 6, a power source E is connected to the center electrode 36 a and the common electrode 37, and a voltage is applied between the center electrode 36 a and the common electrode 37. Note that the waveform of the voltage applied by the power source E is a sinusoidal waveform.

When the voltage applied between the center electrode 36a and the annular electrode 36b and the common electrode 37 is increased by the power source E, the orientation of the liquid crystal 35 changes, so that the focal length of the light emitted from the liquid crystal lens 31 is the time. Change with.
As the focal length changes, the moving unit 15 moves the laser light source 2 along the optical axis O so that the laser light source 2 is located at the focal position, as in the first embodiment. As a result, as in the first embodiment, the beam diameter for illuminating the effective region P of the hologram element 4 changes from Sa to Sb.

  In the illuminating device 30 which concerns on this embodiment, the effect similar to the illuminating device 1 of 1st Embodiment can be acquired. Furthermore, in the illumination device 30 of the present embodiment, since the liquid crystal lens 31 is used as the variable focus lens, it can be manufactured in the same process as the manufacturing method of a normal liquid crystal panel, and thus the manufacturing cost can be suppressed. It becomes.

[Third Embodiment]
Next, a third embodiment according to the present invention will be described with reference to FIG.
The illumination device 40 according to the present embodiment is a first embodiment in that it includes a plurality of light sources 41a, 42a, 43a and variable focus lenses 41b, 42b, 43b provided corresponding to the light sources 41a, 42a, 43a, respectively. Different from form. Other configurations are the same as those of the first embodiment.

As shown in FIG. 8, the illuminating device 40 includes a first light source 41 having a laser light source (light source) 41a and a liquid lens (variable focus lens) 41b, a laser light source (light source) 42a, and a liquid lens (variable focus lens). And a third light source 43 having a laser light source (light source) 43a and a liquid lens (variable focus lens) 43b. The three light sources 41, 42, 43 are arranged side by side so as to face the incident end face 4 a of the hologram element 4.
The laser beams L emitted from the laser light sources 41a, 42a, and 43a are converted into parallel beams by the liquid lenses 41b, 42b, and 43b, respectively, and illuminate the effective area P of the hologram element 4. The control method of the liquid lenses 41b, 42b, 43b is the same as that in the first embodiment. Further, the laser light sources 41a, 42a, 43a are moved along the optical axis O by the moving unit 15 according to the curvature of the oil droplets 24 of the liquid lenses 41b, 42b, 43b so as to be arranged at the focal position. Thereby, the beam diameters S1, S2, and S3 emitted from the liquid lenses 41b, 42b, and 43b change with the curvatures of the liquid lenses 41b, 42b, and 43b.

  The control unit (not shown) controls the voltage applied to each of the liquid lenses 41b, 42b, and 43b so that the focal position of at least one of the liquid lenses 41b, 42b, and 43b constantly changes. ing. In other words, the control unit does not change the focal position of the liquid lenses 41b, 42b, and 43b (when the oil droplet curvature starts to decrease from the largest state or when the oil droplet curvature begins to increase from the smallest state). Is controlled so that the curvature of at least one of the liquid lens 42b of the second light source 42 and the liquid lens 43b of the third light source 43 changes. Thus, the curvature of at least one of the liquid lenses 41b, 42b, and 43b always changes. That is, at least one of the beam diameters S1 to S3 of the laser light L incident on the effective area P of the hologram element 4 is constantly changed.

  In the illuminating device 40 according to this embodiment, since at least one of the beam diameters S1 to S3 of the laser light that illuminates the hologram element 4 is changed, speckle noise is generated in the light emitted from the hologram element 4. Can be reduced. Thereby, it becomes possible to irradiate the target illumination region S with uniform illumination light that more reliably suppresses the generation of speckle noise without reducing the light utilization efficiency.

[Fourth Embodiment]
Next, a fourth embodiment will be described. In the present embodiment, an example of a projector to which the illumination device 1 described in each of the above embodiments is applied will be described.

  FIG. 9 is a schematic configuration diagram illustrating a projector including the illumination device 1 (1R, 1G, 1B) described in the first embodiment. In the present embodiment, a projector type projector PJ1 that projects color light including image information generated by a spatial light modulation device on a screen via a projection system will be described as an example.

  In FIG. 9, the projection type projector PJ1 includes a projection unit U that projects light including image information on a screen 100 (display surface). An image is formed on the screen 100 by projecting light from the projection unit U onto the screen 100. The projection type projector PJ1 of the present embodiment uses the screen 100 as a reflection type screen, and projects light including image information from the front side of the screen 100 onto the screen 100.

  The projection unit U includes a first illumination device 1R that can illuminate the irradiation surface 11 with the first basic color light (red light), and a second illumination device that can illuminate the irradiation surface 11 with the second basic color light (green light). 1G, a third illumination device 1B that can illuminate the irradiation surface 11 with the third basic color light (blue light), and an incident surface (irradiated surface) 11 that is illuminated by the first illumination device 1R. The first spatial light modulation device (light modulation device) 50R that modulates the received light according to image information and the incident surface (illuminated surface) 11 illuminated by the second illumination device 1G, and the illuminated light A second spatial light modulation device (light modulation device) 50G that modulates light according to image information and an incident surface (illuminated surface) 11 illuminated by the third illumination device 1B. Third spatial light modulation device (light modulation device) 50B that performs light modulation according to information, and spatial light modulation devices 50R, 5 A dichroic prism (color synthesizing means) 51 that synthesizes the basic color lights modulated by G and 50B, and a projection system (projection device) 52 that projects the light generated by the dichroic prism 51 onto the screen 100 are provided. . Each of the spatial light modulators 50R, 50G, and 50B includes a liquid crystal device. In the following description, the spatial light modulator is appropriately referred to as a light valve.

  The light valve includes an incident-side polarizing plate, a panel having a liquid crystal sealed between a pair of glass substrates, and an emission-side polarizing plate. A pixel electrode and an alignment film are provided on the glass substrate. The light valve constituting the spatial light modulator transmits only light in a predetermined vibration direction, and the basic color light incident on the light valve is light-modulated by passing through the light valve.

  The laser light source (light source) 2 of the first lighting device 1R emits red (R) laser light. The first illumination device 1R illuminates the incident surface 11 of the first light valve 50R based on the red laser light.

  The laser light source (light source) 2 of the second illumination device 1G emits green (G) laser light. The second illumination device 1G illuminates the incident surface 11 of the second light valve 50G based on the green laser light.

  The laser light source (light source) 2 of the third illumination device 1B emits blue (B) laser light. The third illumination device 1G illuminates the incident surface 11 of the third light valve 50B based on the blue laser light.

  Each basic color light (modulated light) modulated by passing through each light valve 50R, 50G, 50B is synthesized by the dichroic prism 51. The dichroic prism 51 is constituted by a dichroic prism, and the red light (R), the green light (G), and the blue light (B) are combined by the dichroic prism 51 to become full color combined light. The full color combined light emitted from the dichroic prism 51 is supplied to the projection system 52. The projection system 52 projects full color combined light on the screen 100. The projection system 52 is a so-called enlargement system that enlarges an incident-side image and projects it on the screen 100.

  The projection unit U projects full-color composite light including image information via the light valves 50R, 50G, and 50B illuminated by the lighting devices 1R, 1G, and 1B onto the screen 100 using the projection system 52. As a result, a full-color image is formed on the screen 100. The viewer appreciates the image projected on the screen 100 by the projection unit U.

The light valves 50R, 50G, and 50B of the projector PJ1 of the present embodiment are illuminated with irradiation light having a uniform illuminance distribution by the lighting devices 1R, 1G, and 1B in which speckle noise is suppressed. Therefore, the projector PJ1 can display an image in which glare (scintillation) is suppressed.
Furthermore, compared to the conventional configuration in which the diffusion plate is rotated, the generation of sound and vibration is less, so that a comfortable viewing can be achieved.

In each of the illumination devices 1R, 1G, and 1B, the time during which the illumination area of the laser light that illuminates the hologram element 4 does not change (when the curvature of the oil droplet starts to decrease from the largest state or when the curvature of the oil droplet is the largest) The return time when the light valve 50R, 50G, 50B starts to return from the small state is the return period of the light valves 50R, 50G, 50B. After that, the time until writing of the next frame is started (vertical blanking period), or the scanning line displayed from left to right returns to the left again (horizontal blanking period). The timing of the change in the curvature of the liquid lens 3 may be controlled. As a result, since the focal position changes while the image is formed, it is possible to suppress the occurrence of speckle noise in the light emitted from the superimposed illumination element, so that the image in which the occurrence of scintillation is suppressed is suppressed. Can be projected.
In addition, the control unit may control the voltage applied to each liquid lens 3 so that the focal position of at least one liquid lens among the liquid lenses 3 used in the illumination devices 1R, 1G, and 1B constantly changes. good.

[Fifth Embodiment]
Next, a fifth embodiment will be described. In the present embodiment, an example of a projector to which the illumination device 1 described in each of the above embodiments is applied will be described.
In the fourth embodiment, a three-plate projector using three liquid crystal light valves has been described as an example. However, in the present embodiment, a single-plate projector PJ2 using one liquid crystal light valve is used as an example. explain.

  In the projector PJ1 of the fourth embodiment, the liquid crystal light valves 50R, 50G, and 50B are respectively disposed between the optical paths between the hologram element 4 and the dichroic prism 51 of each of the illumination devices 1R, 1G, and 1B. In the projector PJ2, one liquid crystal light valve 55 is disposed between the optical paths of the dichroic prism 51 and the projection system 52, as shown in FIG. The configuration of the liquid crystal light valve 55 is the same as that of the liquid crystal light valves 50R, 50G, and 50B of the fourth embodiment.

The projector PJ2 of the present embodiment is sequentially driven in the order of the red illumination device 1R, the green illumination device 1G, and the blue illumination device 1B, and red light, green light, and blue light are sequentially incident on the liquid crystal light valve 55.
The liquid crystal light valve 55 is a transmissive liquid crystal light valve that generates a color image corresponding to the color of the laser light emitted from the dichroic prism 51. The driving timing of the liquid crystal light valve 55 is controlled in synchronization with the driving of the light sources 2R, 2G, and 2B of the lighting devices 1R, 1G, and 1B.
As a result, red light, green light, and blue light sequentially irradiate the liquid crystal light valve 55, and each color light thus irradiated is modulated by passing through the liquid crystal light valve 55, and is enlarged and projected by the projection system 52. Thus, a full color image is formed on the screen 100.

Further, since the projector PJ2 is color-sequentially driven, two illumination devices out of the illumination devices 1R, 1G, and 1B have a time during which laser light is not emitted. Therefore, the time when the curvature of the liquid lens of the illumination device does not change when the laser beam is not emitted (when the curvature of the oil droplet starts to decrease from the largest state, or from the state where the curvature of the oil droplet is the smallest) The voltage applied to the liquid lenses 3R, 3G, and 3B is controlled so that the turn-back time when it starts to increase corresponds.
Thus, while the liquid crystal light valve 55 is irradiated with laser light, the curvatures of the liquid lenses 3R, 3G, and 3B of the illumination devices 1R, 1G, and 1B that emit the laser light always change.

  The projector PJ2 of the present embodiment can display an image with reduced glare (scintillation), similarly to the projector PJ1 of the fourth embodiment. Further, since the projector PJ2 is color sequential driving, there is always a time that does not contribute to the display of the image. Therefore, the time during which the curvature of the liquid lenses 3R, 3G, and 3B of the illumination devices 1R, 1G, and 1B does not change It can be controlled to respond. Therefore, since speckle noise is reliably suppressed in any color light projected on the screen 100, an image with reduced scintillation can be displayed.

Although the dichroic prism 51 is used to irradiate the liquid crystal light valve 55 with each color light, the present invention is not limited to this. That is, as shown in FIG. 11, a projector PJ3 that superimposes laser beams emitted from the light sources 2R, 2G, and 2B by one hologram element 61 may be used. The light sources 2R, 2G, and 2B of the projector PJ3 are arranged to face the incident end face 61a of the hologram element 61. The hologram element 61 has a plurality of recesses 4M designed according to the wavelength of the incident laser light at positions corresponding to the light sources 2R, 2G, and 2B. Then, the hologram element 61 superimposes and illuminates the liquid crystal light valve 55 with each laser beam incident on each recess 4M.
With this configuration, since only one hologram element 61 is required, the entire apparatus can be made compact.

  In the description using FIGS. 9 to 11, a front projection type projector that projects light including image information onto the screen 100 from the front side of the screen 100 has been described as an example. A so-called rear projector that includes a projection unit U on the back side of the screen 100 and projects light including image information from the back side of the screen 100 onto the transmissive screen 100. The lighting device of each of the embodiments can also be applied.

  In each of the embodiments described above, a transmissive liquid crystal device (light valve) is used as the spatial light modulator, but a reflective liquid crystal device can also be used, for example, a DMD (Digital Micromirror Device) or the like. Alternatively, a reflection type light modulator (mirror modulator) may be used.

  Note that the projectors PJ1 and PJ2 of the above-described embodiment have the first, second, and third illumination devices 1R, 1G, and 1B having the laser light sources 2 that can emit the respective basic color lights (R, G, and B). However, a red laser light source that emits red light (R), a green laser light source that emits green light (G), and a blue laser light source that emits blue light (B) are arranged in an array. The structure which has one lighting apparatus may be sufficient. In this case, the laser light emission operation of the laser light source capable of emitting each basic color light is performed in a time-sharing manner, and the operation of the light valve is controlled in synchronism with the laser light emission operation of each laser light source. A full color image can be displayed on the screen 100 with the device and one light valve.

In the projector according to the above-described embodiment, the illumination device 1 illuminates the spatial light modulation device, and an image is displayed on the screen 100 by light passing through the spatial light modulation device. The light modulation device may not be provided. For example, the illumination device 1 of each embodiment described above is applied to a so-called slide projector that illuminates the surface of a slide (positive film) containing image information with the illumination device 1 and projects light including image information on a screen. It is also possible.
Moreover, the illuminating device demonstrated by each above-mentioned embodiment can also be used as a light source of a laser processing machine.
In addition, although the projector of 4th and 5th Embodiment used the illuminating device 1 of 1st Embodiment, you may use the illuminating devices 30 and 40 of 2nd, 3rd Embodiment.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, although a cross dichroic prism is used as the color light combining means, the present invention is not limited to this. As the color light synthesizing means, a dichroic mirror having a cross arrangement to synthesize color light, or a dichroic mirror arranged in parallel to synthesize color light can be used.
Further, although the hologram element has been described as an example of the superimposing illumination element, any element that superimposes incident light, such as a fly array lens or a rod integrator, may be used.

It is principal part sectional drawing which shows the illuminating device which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the superimposition illumination element element of the illuminating device of FIG. It is principal part sectional drawing which shows the structure of the variable focus lens of the illuminating device of FIG. It is a schematic diagram which shows the movement of the light source by the change of the focus position of the variable focus lens of the illuminating device which concerns on 1st Embodiment of this invention. It is principal part sectional drawing which shows the modification of the variable focus lens used for the illuminating device which concerns on 1st Embodiment of this invention. It is principal part sectional drawing which shows the illuminating device which concerns on 2nd Embodiment of this invention. It is a figure which shows the Fresnel pattern used for the variable focus lens of the illuminating device of FIG. It is principal part sectional drawing which shows the illuminating device which concerns on 3rd Embodiment of this invention. It is a schematic block diagram which shows the projector which concerns on 4th Embodiment of this invention. It is a schematic block diagram which shows the projector which concerns on 5th Embodiment of this invention. It is a schematic block diagram which shows the modification of the projector which concerns on 5th Embodiment of this invention.

Explanation of symbols

  PJ1, PJ2, PJ3 ... projector, 1, 30, 40 ... illumination device, 2 ... light source, 2R, 2G, 2B ... light source, 3 ... liquid lens (variable focus lens), 4 ... hologram element (superimposed illumination element), 31 Liquid crystal lens (variable focus lens), 41a, 42a, 43a ... Light source, 50R ... First spatial light modulator (light modulator), 50G ... Second spatial light modulator (light modulator), 50B ... Third space Light modulation device (light modulation device), 52... Projection system (projection device)

Claims (11)

An illumination device that generates illumination light for illuminating a target illumination area on a predetermined illuminated surface,
A light source that emits light;
A variable focus lens that is capable of changing a focal position when light emitted from the light source is incident;
A superimposed illumination element that superimposes the light emitted from the variable focus lens and illuminates the target illumination area;
And a controller that controls the focal position of the variable focus lens to change with time. The light source is movably arranged;
The illumination apparatus according to claim 1, further comprising a light source moving unit that moves the light source in accordance with a change in a focal position of the variable focus lens.   The lighting device according to claim 2, wherein the light source moving unit moves the light source so that the light source is positioned at a focal position of the variable focus lens.   The lighting device according to claim 2 or 3, wherein the light source moving means moves the light source during a time when the focal position of the variable focus lens does not change. A plurality of the light source and the variable focus lens are provided,
The variable focus lens is provided corresponding to each of the plurality of light sources,
5. The control unit according to claim 1, wherein the control unit controls the focal position of at least one of the plurality of variable focus lenses to constantly change. The lighting device described. The variable focus lens includes an oil droplet filled in a container, an electrolytic solution that covers the oil droplet and has a refractive index different from that of the oil droplet, and an electrode that applies a voltage to the electrolytic solution,
The lighting device according to any one of claims 1 to 5, wherein the control unit changes a curvature of the oil droplet by controlling a voltage applied to the electrode. The variable focus lens includes a first substrate on which a circular center electrode and a plurality of concentric annular electrodes having different radii are formed, a second substrate on which a common electrode is formed on one surface, the first substrate, A liquid crystal provided between the second substrate,
6. The control unit according to claim 1, wherein the control unit controls an alignment state of the liquid crystal by controlling a voltage applied to the central electrode, the annular electrode, and the common electrode. The lighting device according to claim 1. The variable focus lens has a plurality of lenses;
6. The control unit according to claim 1, wherein the control unit changes a focal position of the variable focus lens by moving at least one of the plurality of lenses. The lighting device described in 1. The lighting device according to any one of claims 1 to 8,
A light modulation device that modulates light emitted from the illumination device according to an image signal;
A projector comprising: a projection device that projects an image formed by the light modulation device.   The focus position of the variable focus lens is changed by the control unit so that a blanking period of the light modulation device is a time during which the focus position of the variable focus lens does not change. Projector. The illuminating device includes a plurality of the light sources that emit light of different wavelengths, and the variable focus lens provided corresponding to each of the plurality of light sources,
Sequentially injecting the light of the plurality of different wavelengths into the light modulator,
The control unit includes a focal point of the varifocal lens such that a time when the light is not incident on the light modulation device is a time when the focal position of the varifocal lens corresponding to the light source emitting the non-incident light is not changed. The projector according to claim 9, wherein the position is changed.

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