JP2011065021A - Projection type image display and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type image display in which a problem that reduction rate in speckle noise can not be improved is solved while suppressing the deterioration of the image quality of a displayed image. <P>SOLUTION: A light source 11 emits a light beam modulated according to an image signal. A projection part 12 projects the light beam emitted from the light source 11. An optical path length adjustment part 13 adjusts the optical path length of the light beam. A control part 14 controls the optical path length adjustment part 13 on the basis of the image signal so that a plurality of adjusted beams having respectively different wave forms are generated from the light beam emitted from the light source 11 and the respective adjusted beams are projected by being time-divided for the respective pixel positions of a displayed image corresponding to the image signal, thus the control part 14 varies the optical path length of the light beam emitted from the light source 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a projection-type image display device, and more particularly to a projection-type image display device that scans a light beam and displays an image on a screen and a control method thereof.

  There has been proposed a scanning-type image display device that has a light source that emits a light beam such as a laser light source, and projects an image on a screen by scanning the light beam from the light source. The scanning image display device has a problem that image quality is low because spotted noise due to the coherence of the light beam is generated in the display image. This speckled noise is called speckle noise.

  Speckle noise can be reduced by using a delay optical system that divides a light beam into a plurality of light beams, gives an optical path difference to each light beam, and then superimposes each light beam. This is because coherence is reduced by superimposing light beams having optical path differences.

  As a technique relating to the above-described delay optical system, the optical system described in Patent Document 1, the speckle erasing optical apparatus described in Patent Document 2, the speckle reduction apparatus described in Patent Document 3, and the patent document 4 described above. There is a fluorescence endoscope system.

  The optical system described in Patent Document 1 includes a half mirror that reflects and transmits incident light, and a mirror that enters the half mirror using reflected light from the half mirror as re-incident light. The mirror enters the reincident light at a position different from the incident position of the original incident light. Thereby, the transmitted light from the half mirror becomes a plurality of light fluxes having optical path differences.

  A plurality of light beams are condensed on the entrance surface of a homogenizer made of a light pipe or a multimode fiber by a condenser lens. For this reason, the light emitted from the homogenizer becomes light in which a plurality of light beams having optical path differences are overlapped, and speckle noise can be reduced.

  Further, the speckle erasing optical device described in Patent Document 2 is incident on the half mirror again as a laser light source, a half mirror that reflects and transmits a light beam from the laser light source, and light transmitted from the half mirror as re-incident light. Light turning means.

  The light turning means makes the re-incident light incident on the half mirror so that the optical axis of the re-incident light transmitted by the half mirror matches the optical axis of the reflected light by the half mirror of the original light beam.

  Thereby, the transmitted light of the re-incident light and the reflected light of the original light beam overlap each other, and the transmitted light and the reflected light have optical path differences, so that speckle noise can be reduced.

  In addition, the speckle reduction device described in Patent Document 3 includes an optical fiber group including a plurality of fiber strands having different lengths. One end face of the optical fiber group is an incident face, and the other end face is an exit face.

  The light beam incident on the incident surface of the optical fiber group from the light source is divided by each fiber strand. The light beams divided by the fiber strands are emitted overlapping each other on the emission surface of the optical fiber group.

  Thereby, since the length of each fiber strand differs, each light beam divided by each fiber strand has an optical path difference. Therefore, speckle noise can be reduced because a plurality of light beams having optical path differences overlap.

  Further, in the fluorescence endoscope system described in Patent Document 4, a noise reducing device having the same configuration as that of the speckle reducing device described in Patent Document 3 is used.

US Pat. No. 5,224,200 Japanese Patent Publication No. 7-104500 JP 2007-193108 A JP 2008-43493 A

  In a scanning image display device, in order to display an image, the projected light needs to be a beam. Here, the beam refers to light having a very small spatial spread and a very small change in light intensity distribution, such as a laser beam. Even in multimode light having a plurality of modes, light having the above characteristics is included in the beam.

  For this reason, when a delay optical system for reducing speckle noise is applied to a scanning image display apparatus, the light emitted from the delay optical system must also be a beam.

  In the optical system described in Patent Document 1, since a plurality of light beams are condensed on the entrance surface of the homogenizer by the condensing lens, light propagating in the homogenizer becomes light composed of a plurality of light beams having different optical axes. Therefore, the light emitted from the homogenizer does not become a beam.

  Further, in the techniques described in Patent Documents 3 and 4, since the optical axes of the plurality of light beams emitted from the fiber strands do not coincide with each other, the light emitted from the optical fiber group does not become a beam.

  Therefore, it is difficult to apply the techniques described in Patent Documents 1, 3 and 4 to a scanning image display apparatus.

  In the speckle erasing optical device described in Patent Document 2, since the optical axis of the transmitted light of the re-incident light and the optical axis of the reflected light of the original light beam coincide, the multiplexed light in which the transmitted light and the reflected light overlap each other. Light becomes a beam.

  However, in the speckle erasing optical apparatus, although the optical path lengths of the transmitted light and the reflected light included in the multiplexed light are different from each other, the optical path lengths of the transmitted light and the reflected light included in the multiplexed light are constant. Since the wavefront shape of the light beam is determined according to the optical path length of the light beam, the wavefront shapes on the screen of the transmitted light and the reflected light are constant. For this reason, the wavefront shape on the screen of the multiplexed light in which the transmitted light and the reflected light are superimposed is also constant.

  Since the speckle pattern changes according to the wavefront shape on the screen of the light beam, if the wavefront shape is constant, the speckle pattern is also constant. Therefore, in the speckle erasing optical apparatus, the speckle pattern is integrated over time, and speckle noise is emphasized. For this reason, there has been a problem that the reduction rate of speckle noise becomes low.

  Note that the speckle noise reduction rate can be improved by shifting the optical axes of transmitted light and reflected light included in the multiplexed light. However, if the optical axis is shifted, the aperture of the multiplexed light increases, and the image quality of the display image is greatly deteriorated.

  An object of the present invention is to provide a projection-type image display apparatus and a control method thereof that solve the above-mentioned problem that the speckle reduction rate cannot be improved while suppressing deterioration of the image quality of the display image. It is to be.

  A projection-type image display device according to the present invention adjusts an optical path length of a light source that emits a light beam modulated according to a video signal, a projection unit that projects the light beam emitted from the light source, and the light beam A plurality of adjustment beams having different wavefront shapes are generated from the adjustment means and the light beam, and each adjustment beam is projected in a time-division manner to each pixel position of the image corresponding to the video signal. And control means for changing the optical path length of the light beam by controlling the adjusting means based on the video signal.

  A control method for a projection-type image display apparatus according to the present invention includes: a light source that emits a light beam modulated according to a video signal; a projection unit that projects a light beam emitted from the light source; and an optical path length of the light beam. A control method for a projection-type image display apparatus, comprising: an adjusting unit that adjusts an optical path length; and an adjusting unit that adjusts an optical path length of the light beam, wherein a plurality of adjusting beams having different wavefront shapes are generated from the light beam. And the adjustment means is controlled on the basis of the video signal so that each adjustment beam is projected in a time-sharing manner for each pixel position of the image corresponding to the video signal. A control step for changing the length;

  According to the present invention, it is possible to improve the speckle reduction rate while suppressing deterioration of the image quality of the display image.

It is the block diagram which showed the structure of the projection type image display apparatus of 1st embodiment by this invention. It is explanatory drawing which showed the shape near the beam waist of a light beam. It is the graph which showed light intensity distribution which is a far field image. It is the block diagram which showed the structure of the projection type image display apparatus of 2nd embodiment by this invention. It is the block diagram which showed the structure of the projection type image display apparatus of 3rd embodiment by this invention. It is the block diagram which showed the structure of the projection type image display apparatus of 4th embodiment by this invention. It is the external view which showed typically an example of the rotating mirror. It is the block diagram which showed the structure of the projection type image display apparatus of 5th embodiment by this invention. It is the block diagram which showed the structure of the projection type image display apparatus of 6th Embodiment by this invention. It is the block diagram which showed an example of the structure of the control part. It is a timing chart for demonstrating an example of operation | movement of a projection type image display apparatus. It is a timing chart for demonstrating the other example of operation | movement of a projection type image display apparatus. It is explanatory drawing for demonstrating an example of switching speed. It is explanatory drawing for demonstrating the other example of switching speed.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, components having the same function may be denoted by the same reference numerals and description thereof may be omitted.

  FIG. 1 is a block diagram showing a configuration of a projection type image display apparatus according to a first embodiment of the present invention. In FIG. 1, the projection type image display device 1 includes a light source 11, a projection unit 12, an optical path length adjustment unit 13, and a control unit 14.

  The light source 11 is, for example, a laser diode. The light source 11 is not limited to the laser diode and can be changed as appropriate.

  The light source 11 emits a light beam modulated according to the video signal toward the projection unit 12 via the optical path length adjustment unit 13. The light beam is, for example, laser light, and may be single mode light or multimode light as long as the spatial spread is very small.

  The projection unit 12 is an example of a projection unit. The projection unit 12 projects the light beam emitted from the light source 11 onto the screen 100. As a result, an image corresponding to the video signal is displayed on the screen 100.

  The optical path length adjustment unit 13 is an example of an adjustment unit. The optical path length adjustment unit 13 is provided between the light source 11 and the projection unit 12. The optical path length adjustment unit 13 adjusts the optical path length from the light source 11 to the projection unit 12.

  The control unit 14 is an example of a control unit. Based on the video signal, the control unit 14 controls the optical path length adjustment unit 13 to change the optical path length of the light beam emitted from the light source 11. Specifically, the control unit 14 generates a plurality of adjustment beams having different wavefront shapes from the light beam, and each adjustment beam is time-divided with respect to each pixel position of the display image corresponding to the video signal. The optical path length of the light beam is changed so that it is projected.

  For example, the control unit 14 changes the optical path length so that two adjustment beams are generated one by one in order, and each adjustment beam is alternately projected to each pixel position.

  Next, the wavefront shape of the light beam will be described.

  FIG. 2 is an explanatory view showing the shape of the vicinity of the beam waist of the light beam. In FIG. 2, it is assumed that the light beam is a single mode Gaussian beam. A Gaussian beam is a light beam in which the light intensity distribution in the cross section is substantially Gaussian.

  When the light beam is a single-mode Gaussian beam, a far field image (FFP: Far Field Pattern) of the light beam is expressed by Equation 1. The far-field image is a light intensity distribution representing the wavefront shape of the light beam at a position sufficiently away from the light source 11. Usually, since the position of the screen 100 can be regarded as being sufficiently away from the light source 11, the far-field image represented by Equation 1 represents the wavefront shape of the light beam on the screen 100.

In Equation 1, θ represents the radiation angle of the light beam with reference to the position of the beam waist. Specifically, the radiation angle θ is an angle formed by the optical axis of the light beam, a line connecting the center of the beam waist of the light beam and a point on the screen 100. θ ₀ represents a divergence half angle which is a radiation angle θ at which the light intensity becomes 1 / e ² . The peak value of the light intensity distribution, which is a far-field image, is normalized to 1.

  The far-field image is a light intensity distribution representing the wavefront shape of the light beam at a position sufficiently away from the light source 11. Usually, since the position of the screen 100 can be regarded as being sufficiently away from the light source 11, the far-field image represented by Equation 1 represents the wavefront shape of the light beam on the screen 100. The far-field image can be represented by the graph shown in FIG. In FIG. 3, the horizontal axis represents the radiation angle θ, and the vertical axis represents the light intensity I.

The divergence half angle θ ₀ is substantially constant in a region sufficiently away from the position of the beam waist of the light beam, and is the same as the 1 / e ² diameter of the light beam expressed by Equation ² . The 1 / e ² diameter is the width of the light beam at which the light intensity is 1 / e ² .

In Equation 2, ω ₀ represents the width of the beam waist of the light beam, λ represents the wavelength of the light beam, and z represents the distance from the position of the beam waist in the optical axis direction of the light beam.

  On the other hand, as shown in FIG. 2, in the vicinity of the position of the beam waist, the divergence angle θ is not constant and decreases rapidly as it approaches the position of the beam waist.

The wavefront shape of the light beam is perpendicular to the traveling direction of the beam. For this reason, since the traveling direction of the light beam changes from 0 ° to θ _{0 with} respect to the optical axis except near the position of the beam waist, the wavefront shape of the light beam draws a curve and the light beam becomes a spherical wave. . On the other hand, at the beam waist position, the traveling direction of the light beam is 0 ° with respect to the optical axis (that is, parallel to the optical axis), so that the wavefront shape of the light beam is relative to the optical axis. The light beam becomes a plane wave. Further, in the vicinity of the position of the beam waist, the light beam continuously changes from a plane wave to a spherical wave as the distance from the beam waist position increases. Each wavefront shape before and after the beam waist is a line target with a line passing through the position of the beam waist and perpendicular to the optical axis as a target axis.

  Therefore, if the position of the screen 100 is in the vicinity of the beam waist, the control unit 14 can change the wavefront shape of the light beam on the screen 100 by changing the optical path length of the light beam.

  Also, when the focal position, which is the position of the beam waist of the light beam, is on the screen 100, the image quality of the display image is the best because the beam diameter is the smallest. However, even if the focal position is slightly deviated from the screen 100, the beam diameter hardly changes as shown in FIG.

  Furthermore, the wavefront shape of the light beam varies greatly before and after the focal position. For this reason, when the distance from the light source 11 to the screen 100 is determined in advance as in a rear projection television, the control unit 14 changes the optical path length of the light beam so that the focal position is switched before and after the screen 100. It is desirable.

  When the light beam is a multimode beam composed of a plurality of Gaussian beams, the far-field image of the light beam can be represented by superposition of the far-field images represented by Equation 1.

  According to the present embodiment, the light source 11 emits a light beam modulated according to the video signal. The projection unit 12 projects the light beam emitted from the light source 11. The optical path length adjustment unit 13 adjusts the optical path length of the light beam. The control unit 14 generates a plurality of adjustment beams having different wavefront shapes from the light beam emitted from the light source 11, and each adjustment beam is time-divided with respect to each pixel position of the display image according to the video signal. Based on the video signal, the optical path length adjustment unit 13 is controlled so that the optical path length of the light beam emitted from the light source 11 is changed.

  In this case, a plurality of adjustment beams having different wavefront shapes are projected in a time-sharing manner with respect to each pixel position of the display image. The speckle pattern varies depending on the wavefront shape.

  Therefore, a plurality of speckle patterns can be generated at each pixel position of the display image. Therefore, it is possible to make the observer observe speckles in which a plurality of speckle patterns are averaged over time. Therefore, speckle noise can be reduced. In addition, since it is not necessary to increase the diameter of the light beam, it is possible to suppress deterioration in the image quality of the display image. That is, it is possible to improve the speckle noise reduction rate while suppressing deterioration in the image quality of the display image.

  Further, in the present embodiment, since the optical path length is changed from the light source 11 to the screen 100 by a minute amount compared with the optical path length, the specs are hardly influenced on the optical components and optical design of the existing projection type image display apparatus. Can be reduced.

  Next, a second embodiment will be described.

  In the present embodiment, a more detailed configuration of the projection type image display device 1 will be described.

  FIG. 4 is a block diagram showing the configuration of the projection type image display apparatus of the second embodiment. In FIG. 4, the projection type image display device 1 includes a light source 11, a projection unit 12, an optical path length adjustment unit 13, a control unit 14, and a collimator lens 15.

  The collimator lens 15 converts the light beam emitted from the light source 11 into parallel light.

  The optical path length adjustment unit 13 adjusts the optical path length of the light beam converted into parallel light by the collimator lens 15.

  The optical path length adjustment unit 13 includes a half mirror 21, a first optical system including mirrors 22 and 23, and a half mirror 24, and shutters 25 and 26.

  The half mirror 21 is an example of a dividing unit. The half mirror 21 splits the light beam that has been collimated by the collimator lens 15 into a plurality of split beams.

  More specifically, the half mirror 21 transmits and reflects the light beam and divides the light beam into transmitted light and reflected light. This transmitted light and reflected light become a split beam. Hereinafter, the reflected light from the half mirror 21 is referred to as a first split beam, and the transmitted light from the half mirror 21 is referred to as a second split beam.

  The first optical system is an example of optical means. The first optical system gives an optical path difference to the first divided beam and the second divided beam divided by the half mirror 21.

  Specifically, the mirror 22 reflects the first split beam and enters the mirror 23. The mirror 23 reflects the first split beam incident from the mirror 22 and enters the half mirror 24. The second split beam is directly incident on the half mirror 24 without passing through the mirrors 22 and 23.

  The half mirror 24 reflects the first split beam incident from the mirror 23 to generate and output as an adjustment beam. The half mirror 24 transmits the second split beam incident from the half mirror 21 to generate and emit an adjustment beam.

  As a result, the optical path length of the first split beam becomes longer than the optical path length of the second split beam by the amount of passing through the mirrors 22 and 23. Therefore, an optical path difference is given to the first split beam and the second split beam.

  The half mirror 24 is arranged so that the optical axis of the adjustment beam is constant. That is, the half mirror 24 is emitted as an adjustment beam, the optical axis of the beam where the first split beam is reflected by the half mirror 24, and the second split beam which is emitted as the adjustment beam passes through the half mirror 24. It arrange | positions so that the optical axis of a beam may correspond.

  The shutters 25 and 26 are examples of shutter means. The shutters 25 and 226 are provided on the respective optical paths of the first split beam and the second split beam. The shutters 25 and 26 are openable and closable. When the shutters 25 and 26 are opened, the shutters 25 and 26 are in a transmission state that transmits the split beam on the optical path. When the shutters 25 and 26 are closed, the shutters 25 and 26 are in a shielded state.

  In the present embodiment, the shutter 25 is provided between the mirrors 22 and 23 and switches between transmission and shielding of the first split beam. The shutter 26 is provided between the half mirrors 21 and 24 and switches between transmission and shielding of the second divided beam. The shutter 25 may be provided between the half mirror 21 and the mirror 22, or may be provided between the mirror 23 and the half mirror 24.

  Thus, when the shutter 25 is opened, the first divided beam is generated as an adjustment beam, and when the shutter 26 is opened, the second divided beam is generated as an adjustment beam.

  The projection unit 12 projects the adjustment beam emitted from the optical path length adjustment unit 13 onto the screen 100 and displays a display image corresponding to the video signal. In the present embodiment, the projection unit 12 is a scanner that two-dimensionally scans the adjustment beam and projects it onto the screen 100.

  The controller 14 changes the optical path length of the light beam by switching the opening and closing of the shutters 25 and 26, and emits the first divided beam and the second divided beam one by one as the adjustment beam in order. At this time, the control unit 14 changes the opening and closing of the shutters 25 and 26 so that the first divided beam and the second divided beam are projected as time-division beams as the adjustment beams with respect to the pixel positions of the display image.

  For example, the control unit 14 opens the shutters 25 and 26 alternately so that the first divided beam and the second divided beam are alternately projected as the adjustment beam to each pixel position of the display image.

  Further, the control unit 14 modulates the emitted light emitted from the light source 11 according to the video signal. Thereby, the light source 11 emits a light beam modulated according to the video signal. Further, the control unit 14 drives the scanner which is the projection unit 12 based on the video signal. As a result, a display image corresponding to the video signal is displayed on the screen 100.

  Next, the operation will be described.

  The light beam emitted from the light source 11 is incident on the half mirror 21 of the optical path length adjustment unit 13. The half mirror 21 reflects and transmits the light beam and divides it into a first divided beam and a second divided beam.

  The first split beam is incident on the shutter 25 via the mirror 22. When the shutter 25 is opened, the first split beam passes through the shutter 25 and enters the half mirror 24 via the mirror 23. On the other hand, when the shutter 25 is closed, the first split beam is shielded.

  When the first split beam is incident, the half mirror 24 reflects the first split beam and emits it toward the projection unit 12 as an adjustment beam.

  The second split beam is incident on the shutter 26. When the shutter 26 is opened, the second split beam passes through the shutter 26 and enters the half mirror 24. On the other hand, when the shutter 26 is closed, the second split beam is shielded.

  When the second split beam is incident, the half mirror 24 transmits the second split beam to the projection unit 12 as an adjustment beam by transmitting the second split beam.

  The projection unit 12 two-dimensionally scans the adjustment beam emitted from the half mirror 24 and projects the adjustment beam onto the screen 100 and displays an image corresponding to the video signal on the screen 100.

  The control unit 14 opens the shutters 25 and 26 alternately so that the first divided beam and the second divided beam are alternately projected as adjustment beams on each pixel position of the display image displayed by the projection unit 12. To do.

  According to this embodiment, the half mirror 21 splits the light beam into a plurality of split beams. The first optical system gives an optical path difference to the divided beam divided by the half mirror 21. The shutters 25 and 26 are provided on the respective optical paths of the split beams. The control unit 14 switches between opening and closing the shutters 25 and 26 to change the optical path length of the light beam.

  In this case, the optical path length of the light beam is changed only by switching the opening and closing of the shutters 25 and 26. Therefore, the optical path length can be easily changed.

  Next, a third embodiment will be described.

  In the present embodiment, another configuration example of the optical path length adjustment unit 13 will be described.

  FIG. 5 is a block diagram showing the configuration of the projection type image display apparatus of the third embodiment. 5, the projection type image display apparatus 1 includes a light source 11, an optical path length adjustment unit 13, a projection unit 12, a control unit 14, and a collimator lens 15 similarly to the configuration shown in FIG.

  The optical path length adjustment unit 13 includes an optical switch 31 and a second optical system having a mirror 32 and an optical switch 33.

  The optical switch 31 is an example of a switch unit. The optical switch 31 outputs the light beam that has been collimated by the collimator lens 15 in any of a plurality of predetermined output directions.

  In the present embodiment, the optical switch 31 outputs a light beam in one of two output directions, a first output direction and a second output direction. The light beam output in the first output direction is referred to as a first direction beam, and the light beam output in the second output direction is referred to as a second direction beam.

  The second optical system is an example of optical means. The second optical system gives an optical path difference to the first direction beam and the second direction beam output from the optical switch 31 in each of a plurality of output directions, and the first direction beam and the second direction beam are directed in a specific direction. Exit. The specific direction is a direction toward the projection unit 12.

  Specifically, the mirror 32 reflects the first direction beam output from the optical switch 31 and enters the optical switch 33. The second direction beam output from the optical switch 31 is directly incident on the optical switch 33 without passing through the mirror 32.

  The optical switch 33 emits the first direction beam incident from the mirror 32 and the second direction beam directly incident from the optical switch 31 toward the projection unit 12 as an adjustment beam.

  As a result, the optical path length of the first direction beam becomes longer than the optical path length of the second direction beam by the amount of passing through the mirror 32. Therefore, an optical path difference is given to the first direction beam and the second direction beam.

  The optical switch 33 is arranged so that the optical axis of the adjustment beam is constant. That is, the optical switch 33 is disposed so that the optical axis of the first direction beam emitted as the adjustment beam and the optical axis of the second direction beam emitted as the adjustment beam coincide.

  The optical switches 31 and 33 are, for example, galvanometer mirrors, MEMS (Micro Electro Mechanical Systems) mirrors, electro-optic modulation elements, or acousto-optic modulation elements. The optical switches 31 and 33 are not limited to galvanometer mirrors, MEMS mirrors, electro-optic modulation elements, or acousto-optic modulation elements, and can be changed as appropriate.

  The control unit 14 changes the optical path length of the light beam by switching the output direction of the light beam output from the optical switch 31, and emits the first direction beam and the second direction beam one by one as the adjustment beam in order. To do.

  For example, the control unit 14 alternately sets the first direction beam and the second output direction to the output direction of the light beam output from the optical switch 31 with respect to each pixel position of the display image. The second direction beam is alternately projected as the adjustment beam.

  When the control unit 14 switches the output direction of the light beam, the light beam incident on the optical switch 33 is switched between the first direction beam and the second direction beam. At this time, the control unit 14 switches the optical switch 33 so that the optical axis of the adjustment beam does not change even if the first direction beam is incident on the optical switch 33 or the second direction beam is incident. Process. For example, the control unit 14 switches the output direction of the light beam by the optical switch 31 and applies a different voltage to the optical switch 33 for each output direction of the light beam so that the optical axis of the adjustment beam does not change. .

  Next, the operation will be described.

  The light beam emitted from the light source 11 enters the optical switch 31 of the optical path length adjustment unit 13. The optical switch 31 outputs the light beam in either the first output direction or the second output direction.

  When the optical switch 31 outputs a light beam in the first output direction, the output first light beam that is the light beam enters the optical switch 33 via the mirror 32. The optical switch 33 emits the first direction beam toward the projection unit 12 as an adjustment beam.

  On the other hand, when the optical switch 31 outputs the light beam in the second output direction, the output second light beam that is the light beam is directly incident on the optical switch 33. When the second direction beam is incident, the optical switch 33 emits the second direction beam toward the projection unit 12 as an adjustment beam.

  The control unit 14 outputs from the optical switch 31 so that each of the first split beam and the second split beam is time-divided and projected as an adjustment beam at each pixel position of the image displayed by the projection unit 12. The output direction of the emitted light beam is switched, and a voltage corresponding to the output direction is applied to the optical switch 33.

  According to this embodiment, the optical switch 31 outputs a light beam in any of a plurality of output directions. The second optical system gives an optical path difference to the light beam output in each of the plurality of output directions, and emits the light beam in a specific direction. The control unit 14 switches the output direction of the optical switch 31 and changes the optical path length adjusted by the optical path length adjustment unit 13.

  In this case, an optical path difference is given to the light beams output in each of the plurality of output directions. In addition, the output direction is switched to change the optical path length of the light beam.

  For this reason, it is not necessary to use the split beam obtained by splitting the light beam as the adjustment beam. Therefore, even if the light quantity of the original light beam emitted from the light source 11 is reduced, the display image can be made sufficiently bright. Therefore, power consumption can be reduced.

  Next, a fourth embodiment will be described.

  In the present embodiment, another configuration example of the optical path length adjustment unit 13 will be described.

  FIG. 6 is a block diagram showing the configuration of the projection type image display apparatus of the fourth embodiment. 6, the projection type image display device 1 includes a light source 11, a projection unit 12, an optical path length adjustment unit 13, a control unit 14, and a collimator lens 15 similarly to the configuration shown in FIG.

  The optical path length adjustment unit 13 includes a rotating mirror 41 and a third optical system having mirrors 42 to 46.

  The rotating mirror 41 is an example of a switch unit. The rotating mirror 41 includes a mirror part 41A and a rotation driving part 41B. The mirror unit 41A has a transmission region that transmits light and a reflection region that reflects light. The rotation drive unit 41B rotates the mirror unit 41A around a predetermined axis.

  FIG. 7 is an external view schematically showing an example of the rotating mirror 41.

  In FIG. 7, the mirror part 41A of the rotating mirror 41 is formed of a disk-shaped member. The surface of the disk-shaped member is divided into four congruent fan-shaped regions. Two of the fan-shaped regions are transmissive regions 52, and the remaining regions are reflective regions 51. Further, the transmission regions 52 and the reflection regions 51 are alternately arranged.

  The transmissive region 52 is formed of a light transmissive member such as glass, for example.

  The reflection region 51 is formed of a light reflecting member that reflects light such as a mirror. In the present embodiment, the back surface of the reflection region 51 is also a reflection region formed of a light reflection member. Further, the reflection area on the back surface of the reflection area 51 is a mirror 46.

  The rotation drive unit 41B is, for example, a motor, and is attached to the lower surface of a disk-shaped member that is the mirror unit 41A. The rotation drive unit 41B rotates the mirror unit 41A around an axis that passes through the center of the mirror unit 41A and is perpendicular to the surface of the mirror unit 41A. An axis passing through the center of the mirror part 41A and perpendicular to the surface of the mirror part 41A is a predetermined axis.

  The rotating mirror 41 is arranged such that the light beam that has been collimated by the collimator lens 15 is incident on the mirror portion 41A. In FIG. 7, the incident position 53 of the light beam in the mirror part 41A is shown.

  When the mirror unit 41B is rotated by the rotation drive unit 41B, the light beam is incident on the transmission region 52 and the reflection region 51 alternately. Accordingly, the rotating mirror 41 alternately reflects and transmits the light beam.

  Since the reflected light and the transmitted light from the rotating mirror 41 are output in different directions, the rotating mirror 41 outputs the light beam in any of a plurality of output directions. Hereinafter, the reflected light from the rotating mirror 41 is referred to as a third direction beam, and the transmitted light from the rotating mirror 41 is referred to as a fourth direction beam.

  Returning to FIG. The third optical system is an example of optical means. The third optical system gives an optical path difference to the third direction beam and the fourth direction beam output from the rotary mirror 41 in each of a plurality of output directions, and the third direction beam and the fourth direction beam are directed in a specific direction. Exit.

  Specifically, the mirror 42 reflects the third direction beam reflected by the rotating mirror 41 and enters the mirror 43. The mirror 43 reflects the third direction beam incident from the mirror 42 and enters the mirror 44. The mirror 44 reflects the third direction beam incident from the mirror 43 and enters the mirror 45. The mirror 45 reflects the third direction beam incident from the mirror 44 and enters the mirror 46. The mirror 46 reflects the third direction beam incident from the mirror 45 and emits it toward the projection unit 12 as an adjustment beam.

  Further, the fourth direction beam transmitted through the rotary mirror 41 is emitted directly toward the projection unit 12 as an adjustment beam without passing through the mirrors 42 to 46.

  The optical path length of the third direction beam is longer than the optical path length of the fourth direction beam by the amount of passing through the mirrors 32 to 46. Therefore, an optical path difference is given to the light beams output from the rotating mirror 41 in each of a plurality of output directions.

  The control unit 14 adjusts the rotation speed of the rotary mirror 41 so that the third direction beam and the fourth direction beam are projected in a time-sharing manner as adjustment beams at each pixel position of the display image.

  Next, the operation will be described.

  The light beam emitted from the light source 11 is incident on the mirror part 41 </ b> A of the rotating mirror 41 in the optical path length adjustment part 13.

  When the light beam is incident on the reflection region 51 of the mirror portion 41A, the light beam is reflected by the reflection region 51 and emitted as a third direction beam. The third direction beam is incident on the mirror 46 via the mirrors 42 to 45. The mirror 46 reflects the third direction beam and emits it toward the projection unit 12 as an adjustment beam.

  When the light beam is incident on the transmission region 52 of the mirror portion 41A, the light beam passes through the transmission region 52 as a fourth direction beam. Thereafter, the fourth direction beam is emitted toward the projection unit 12 as an adjustment beam.

  The control unit 14 rotates the rotating mirror 41 so that each of the third direction beam and the fourth direction beam is projected in a time-sharing manner as an adjustment beam at each pixel position of the image displayed by the projection unit 12. The output direction of the light beam from the rotating mirror 41 is switched by adjusting the speed.

  According to the present embodiment, the rotating mirror 41 that has a transmission region and a reflection region and rotates around a predetermined rotation axis is used as the switch means. The control unit 14 switches the output direction of the light beam output from the rotating mirror 41 by adjusting the rotation speed of the rotating mirror.

  In this case, the split beam obtained by splitting the light beam need not be used as the adjustment beam. Therefore, even if the light quantity of the original light beam emitted from the light source 11 is reduced, the display image can be made sufficiently bright. Therefore, power consumption can be reduced.

  Next, a fifth embodiment will be described.

  In the present embodiment, another configuration example of the optical path length adjustment unit 13 will be described.

  FIG. 8 is a block diagram showing the configuration of the projection type image display apparatus of the fifth embodiment. In FIG. 8, the projection type image display apparatus 1 includes a light source 11, an optical path length adjustment unit 13, a projection unit 12, a control unit 14, and a collimator lens 15 similarly to the configuration shown in FIG.

  The optical path length adjustment unit 13 includes a refractive index variable element 61.

  The refractive index variable element 61 is an example of a transmissive element. The refractive index variable element 61 is, for example, an electro-optical element or an acousto-optical element, and is formed of a light transmission member having a variable refractive index. The refractive index variable element 61 transmits the light beam converted into parallel light by the collimator lens 15 to generate and emit an adjustment beam. Since the optical path length is obtained by multiplying the distance that the light beam actually travels by the refractive index of the medium on which the light beam travels, the optical path length also changes when the refractive index changes.

  The control unit 14 generates a plurality of adjustment beams having different wavefront shapes from the light beam, and refracts the refractive index variable element 61 so that each adjustment beam is projected in a time-sharing manner to each pixel position of the display image. The optical path length of the light beam is changed by changing the rate.

  According to the present embodiment, the refractive index variable element 61 transmits a light beam. The control unit 14 changes the optical path length of the light beam by changing the refractive index of the refractive index variable element 61.

  In this case, since it is not necessary to divide the light beam or switch the output direction of the light beam, in addition to the refractive index variable element 61, it is necessary to use an optical component such as a mirror that gives an optical path difference to a plurality of light beams. Disappears. Therefore, the configuration of the optical path length adjustment unit 13 and the projection type image display device 1 can be simplified.

  Next, a sixth embodiment will be described.

  FIG. 9 is a schematic diagram illustrating a configuration example of the optical path length adjustment unit 13 having three optical paths. In FIG. 9, the optical path length adjusting unit 13 includes a dividing unit having the half mirrors 21 and 71, a fourth optical system having the mirrors 23 and 72 to 74 and the half mirror 24, and shutters 25, 26 and 75. .

  The half mirror 21 reflects and transmits the light beam from the light source 11 and divides it into a first divided beam that is reflected light and a second divided beam that is transmitted light.

  The half mirror 71 reflects and transmits the first split beam from the half mirror 21, and splits it into a third split beam that is reflected light and a fourth split beam that is transmitted light.

  Thereby, the splitting unit splits the light beam from the light source into three split beams of the second split beam to the fourth split beam.

  The second split beam is directly incident on the half mirror 24.

  The third split beam is incident on the mirror 72. The mirror 72 reflects the incident third divided beam and enters the mirror 73. The mirror 73 reflects the incident third divided beam and enters the mirror 74. The mirror 74 reflects the incident third divided beam and enters the half mirror 24.

  The fourth split beam is incident on the mirror 23. The mirror 23 reflects the incident fourth divided beam and enters the half mirror 24.

  The half mirror 24 transmits the second split beam incident from the half mirror 21 and emits it as an adjustment beam. Further, the half mirror 24 reflects each of the third split beam and the fourth split beam incident from the mirrors 74 and 23 to generate and output as an adjustment beam.

  As a result, the fourth optical system gives an optical path difference to the second divided beam to the fourth divided beam.

  The shutter 25 is provided between the half mirror 71 and the mirror 23 on the optical path of the fourth split beam, and switches between transmission and shielding of the first split beam. The shutter 26 is provided between the half mirrors 21 and 24 on the optical path of the second split beam, and switches between transmission and shielding of the second split beam. The shutter 75 is provided between the mirrors 72 and 73 on the optical path of the third split beam, and switches between transmission and shielding of the third split beam.

  As a result, the fourth split beam transmitted through the shutter 25 is emitted from the half mirror 24, the second split beam transmitted through the shutter 26 is output from the half mirror 24, and the third split beam transmitted through the shutter 75 is The light is emitted from the half mirror 24.

  As described above, three adjustment beams having different optical path lengths can be emitted. Similarly, the number of adjustment beams can be increased to 4 or more by increasing the number of half mirrors included in the division unit.

  In this embodiment, the light beam is divided as in the second embodiment, but the light beam output direction may be switched as in the third and fourth embodiments. In this case, the number of adjustment beams can be increased to 3 or more by increasing the number of optical switches and rotating mirrors or increasing the number of light beams output by the optical switch.

  Further, when a variable refractive index element is used for the optical path length adjustment unit 13 as in the fifth embodiment, the control unit 14 switches the refractive index of the refractive index variable element in stages, so that the number of adjustment beams is 3 This can be done.

  When the distance from the light source 11 to the screen 100 is predetermined and the number of adjustment beams is 3 or more, the control unit 14 determines that the focal position of the light beam is in front of the screen 100, on the screen 100, and It is desirable to change the optical path length so that it switches in the rear of the screen 100.

  According to the present embodiment, since the number of adjustment beams can be increased, more speckle patterns can be generated, and the speckle noise reduction rate can be further improved. .

  Next, a seventh embodiment will be described.

  The projection type image display apparatus of this embodiment has the same configuration as the projection type image display apparatus of the second embodiment shown in FIG.

  In the present embodiment, the control unit 14 sets the number of shutters that are simultaneously opened to 1 or more.

  For example, the control unit 14 first opens the shutter 25 and closes the shutter 26. Subsequently, the control unit 14 closes the shutter 25 and opens the shutter 26. Then, the control unit 14 opens both the shutters 25 and 26. The control unit 14 switches between opening and closing the shutters 25 and 26 in this order.

  In this case, a first split beam, a second split beam, and a combined beam of the first split beam and the second split beam are generated as the adjustment beam.

  The wavefront shape of the combined beam is the sum of the wavefront shapes of the first split beam and the second split beam. For this reason, the wavefront shape of the combined beam is different from the wavefront shape of the first split beam and the wavefront shape of the second split beam. Therefore, it is possible to project three adjustment beams having different wavefront shapes.

  Further, the light amount of the combined beam is the sum of the light amounts of the first split beam and the second split beam, and thus becomes larger than the light amounts of the first split beam and the second split beam.

  Therefore, when the shutters 25 and 26 are simultaneously opened, the control unit 14 makes a plurality of adjustments by halving the light amount of the light beam emitted from the light source 11 compared to when one of the shutters 25 and 26 is opened. It is desirable to make the amount of light of each beam equal.

  Even when the optical path length adjustment unit 13 has the configuration shown in FIG. 9, the control unit 14 may set the number of shutters to be simultaneously opened to 1 or more. In this case, the control unit 14 adjusts the light amount of the light beam emitted from the light source 11 according to the number of shutters opened simultaneously.

  Specifically, when the number of shutters that are simultaneously opened is M, the control unit 14 sets the light amount of the light beam to 1 / M times the light amount of the light beam when the number of shutters that are simultaneously opened is 1. To do. M is an integer of 1 or more.

  According to the present embodiment, the control unit 14 sets the number of shutters that are simultaneously opened to 1 or more. In this case, the number of adjustment beams having different wavefront shapes can be increased, so that the speckle noise reduction rate can be further improved. In addition, since it is not necessary to add a new optical component such as a mirror in order to increase the number of adjustment beams, it is possible to suppress an increase in the optical path length adjustment unit 13. Therefore, it is possible to further improve the speckle noise reduction rate without increasing the optical path length adjustment unit 13.

  Next, an eighth embodiment will be described.

  In the present embodiment, the control unit 14 will be described in more detail.

  FIG. 10 is a block diagram illustrating a configuration example of the control unit 14. In FIG. 10, the control unit 14 includes a signal processing unit 81, a timing extraction unit 82, and a drive unit 83.

  A video signal is input to the signal processing unit 81. The signal processing unit 81 performs signal processing on the video signal. The signal processing is, for example, γ correction.

  The timing extraction unit 82 extracts a frame rate indicating the speed at which the display image is switched from the video signal subjected to the signal processing by the signal processing unit 81.

  The drive unit 83 changes the optical path length adjusted by the optical path length adjustment unit 13 at a switching speed corresponding to the frame rate extracted by the timing extraction unit 82. For example, the drive unit 83 switches the optical path length at the same speed as the frame rate.

  The operations of the timing extraction unit 82 and the drive unit 83 differ depending on the configuration of the optical path length adjustment unit 13. Therefore, the timing extraction unit 82 and the drive unit 83 are designed according to the configuration of the optical path length adjustment unit 13.

  Hereinafter, the operation of the control unit 14 will be described for each configuration of the optical path length adjustment unit 13. It is assumed that the switching speed is the same speed as the frame rate.

  FIG. 11 is a timing chart for explaining an example of the operation of the control unit 14 when the optical path length adjustment unit 13 has the configuration shown in FIG. It is assumed that three frames with frame numbers N, N + 1, and N + 2 are displayed in succession.

  First, a video signal is input to the signal processing unit 81. The signal processing unit 81 performs signal processing such as γ correction on the video signal, and outputs the video signal subjected to the signal processing to the timing extraction unit 82.

  Subsequently, when receiving the video signal, the timing extraction unit 82 extracts the frame rate from the video signal. The timing extraction unit 82 outputs a drive signal indicating a change in the optical path length to the drive unit 83 at the same switching speed as the frame rate. At this time, it is desirable that the timing extraction unit 82 outputs the drive signal in accordance with the timing at which the frame of the display image is switched.

  Each time the drive unit 83 receives a drive signal, the drive unit 83 outputs an open signal indicating opening to one of the shutters 25 and 26 and outputs a close signal indicating closing to the other. At this time, every time the drive unit 83 receives the drive signal, the drive unit 83 switches the shutter that is the output destination of the open signal and the close signal. The shutter that has received the opening signal is opened, and the shutter that has received the closing signal is closed.

  When the optical path length adjustment unit 13 has the configuration shown in FIG. 5, the timing extraction unit 82 has the same switching speed as the frame rate, similarly to the case where the optical path length adjustment unit 13 has the configuration shown in FIG. A drive signal is input to the drive unit 83.

  The drive unit 83 outputs a direction switching signal for switching the output direction to the optical switch 31 and performs a switching process on the optical switch 31 every time a drive signal is input.

  Each time the optical switch 31 receives a direction switching signal, the optical switch 31 switches the output direction of the light beam. Further, every time the direction switch signal is received, the optical switch 33 is configured so that the optical axes of the light beams coincide with each other regardless of whether the first light beam is incident or the second light beam is incident. Switch to.

  FIG. 12 is a timing chart for explaining the operation of the control unit 14 when the optical path length adjustment unit 13 has the configuration shown in FIGS. 6 and 7. FIG. 12 shows the incident position of the light beam on the rotating mirror when the frames of the frame numbers N, N + 1 and N + 2 of the video signal are displayed.

  When the frame rate is extracted from the video signal, the timing extraction unit 82 inputs a drive signal indicating a rotation speed of ¼ of the frame rate to the drive unit 83.

  When the drive signal is input, the drive unit 83 supplies power to the rotation drive unit 41B so that the mirror unit 41A rotates at the rotation speed indicated by the drive signal. Thereby, the incident position 53 of the light beam in the mirror part 41A is switched in the transmission region 52 and the reflection region 51 for each frame.

  When the optical path length adjustment unit 13 has the configuration shown in FIG. 8, the timing extraction unit 82 is driven at the same speed as the frame rate, similarly to the case where the optical path length adjustment unit 13 has the configuration shown in FIG. A signal is input to the drive unit 83. The drive unit 83 changes the refractive index of the refractive index variable element 61 every time a drive signal is input.

  When the control unit 14 operates as described above, an adjustment beam having a different optical path length is projected onto the screen 100 for each frame of the display image, and thus a plurality of adjustments having different optical path lengths at each pixel position of the display image. The beam is projected in a time-sharing manner.

  In the above example, the switching speed matches the frame rate, but actually, the switching speed may not match the frame rate. For example, the switching speed may be an integer multiple of 1 or more excluding a multiple of the number of adjustment beams of the frame rate.

  FIG. 13 is an explanatory diagram for explaining the switching speed when the number of adjustment beams is two. In FIG. 13, frames with frame numbers N, N + 1, and N + 2 are shown. Each of the two adjustment beams is referred to as adjustment beams A and B.

  When the switching speed is three times the frame rate, the adjustment beams A and B are alternately projected on each pixel position for each frame. On the other hand, when the switching speed is four times the frame rate, the adjustment beam having the same optical path length is projected to each pixel position even if the frame is switched.

  FIG. 14 is an explanatory diagram for explaining the switching speed when the number of adjustment beams is three. In FIG. 14, frames with frame numbers N, N + 1, and N + 2 are shown. Let each of the three adjustment beams be adjustment beams C, D, and E.

  When the switching speed is twice and four times the frame rate, the adjustment beams C, D, and E are sequentially projected to each pixel position for each frame. On the other hand, if the switching speed is four times the frame rate, the adjustment beam having the same optical path length is projected to each pixel even if the frame is switched.

  According to the present embodiment, the optical path length of the light beam is changed at a speed that is an integer multiple of 1 or more excluding a multiple of the number of adjustment beams of the frame rate of the video signal.

  In this case, a plurality of adjustment beams can be appropriately time-divided and projected onto each pixel position of the display image. In addition, the switching speed can be made relatively small.

  Next, a ninth embodiment will be described.

  In the present embodiment, the control unit 14 changes the optical path length of the light beam so that the adjustment beam is projected in a time-division manner within the rendering time during which each pixel is depicted.

  More specifically, the timing extraction unit 82 of the control unit 14 calculates a drawing time based on the video signal. For example, the timing extraction unit 82 extracts the frame rate and the number of pixels from the video signal, and calculates the drawing time by dividing the frame rate by the number of pixels.

  The drive unit 83 uses the optical path length adjustment unit 13 to change the optical path length of the light beam so that the optical path length is switched by the number of adjustment beams within the rendering time calculated by the timing extraction unit 82.

  When the optical path length adjustment unit 13 has the configuration shown in FIG. 4, FIG. 5, FIG. 8, or FIG. 9, the timing extraction unit 82 drives the drive signal every switching time obtained by dividing the drawing time by the number of adjustment beams. Input to part 83.

  The driving unit 83 changes the opening / closing of the shutters 25, 26 and 75, the output direction of the light beam output from the optical switch 31, or the refractive index of the refractive index variable element 61 each time a driving signal is input. Then, the optical path length of the light beam is changed.

  When the optical path length adjustment unit 13 has the configuration shown in FIGS. 6 and 7, the timing extraction unit 82 has a drive signal indicating a rotation speed that is 1/2 of the value obtained by dividing the rendering time by the number of adjustment beams. Is input to the drive unit 83.

  When the drive signal is input, the drive unit 83 supplies power to the rotation drive unit 41B so that the mirror unit 41A rotates at the rotation speed indicated by the drive signal.

  According to the present embodiment, the control unit 14 changes the optical path length of the light beam so that the adjustment beam is time-divisionally projected within the rendering time during which each pixel is depicted.

  In this case, a plurality of adjustment beams can be appropriately time-divided and projected onto each pixel position of the display image.

  In each embodiment described above, the illustrated configuration is merely an example, and the present invention is not limited to the configuration.

DESCRIPTION OF SYMBOLS 1 Projection type image display apparatus 11 Light source 12 Projection part 13 Optical path length adjustment part 14 Control part 21, 24, 71 Half mirror 22, 23, 32, 42-46, 72-74 Mirror 25, 26, 75 Shutter 31, 33 Light Switch 41 Rotating mirror 41A Mirror part 41B Rotation drive part 51 Reflection area 52 Transmission area 61 Refractive index variable element

Claims (13)

A light source that emits a light beam modulated in accordance with a video signal;
Projecting means for projecting a light beam emitted from the light source;
Adjusting means for adjusting the optical path length of the light beam;
The video signal is generated such that a plurality of adjustment beams having different wavefront shapes are generated from the light beam, and each adjustment beam is projected in a time-sharing manner to each pixel position of an image corresponding to the video signal. And a control means for changing the optical path length of the light beam by controlling the adjusting means. In the projection type image display device according to claim 1,
The adjusting means includes
Splitting means for splitting the light beam into a plurality of split beams;
Optical means for providing an optical path difference to the plurality of split beams;
A plurality of openable and closable shutter means provided on the respective optical paths of the plurality of split beams,
The control means is a projection type image display device that changes the optical path length by switching opening and closing of the plurality of shutter means. In the projection type image display device according to claim 2,
The said control means is a projection type image display apparatus which makes 1 or more the number of shutter means simultaneously open | released among these shutter means. In the projection type image display device according to claim 1,
The adjusting means includes
Switch means for outputting the light beam in any of a plurality of output directions;
Optical means for giving an optical path difference to the light beams output in each of the plurality of output directions, and emitting the light beams output by the switch means in a specific direction, and
The control unit is a projection type image display device that changes an optical path length by switching an output direction by the switch unit. In the projection type image display device according to claim 4,
The projection type image display device, wherein the switch means is a galvanometer mirror, a MEMS mirror, an electro-optic modulation element, or an acousto-optic modulation element. In the projection type image display device according to claim 4,
The switch means is a rotary mirror that has a transmission region that transmits light and a reflection region that reflects light, and rotates about a predetermined axis.
The projection type image display device, wherein the control means adjusts a rotation speed of the rotating mirror to switch the output direction. In the projection type image display device according to claim 1,
The adjusting means includes a transmissive element that transmits the light beam,
The said control means is a projection type image display apparatus which changes the said optical path length by changing the refractive index of the said transmissive element. In the projection type image display device according to any one of claims 1 to 7,
The projection type image display device, wherein the control unit changes the optical path length so that the plurality of adjustment beams are projected in a time-division manner within a drawing time for drawing each pixel of the image. In the projection type image display device according to any one of claims 1 to 7,
The projection type image display device, wherein the control means changes the optical path length at a speed that is an integer multiple of 1 or more excluding a multiple of the number of the adjustment beams of a frame rate of the video signal. In the projection type image display device according to any one of claims 1 to 9,
The projection means is a projection type image display device that is a scanner that projects by scanning the light beam. A light source that emits a light beam modulated in accordance with a video signal; a projection unit that projects the light beam emitted from the light source; an adjustment unit that adjusts an optical path length of the light beam; and an optical path length of the light beam. A control method for a projection-type image display device comprising:
The video signal is generated such that a plurality of adjustment beams having different wavefront shapes are generated from the light beam, and each adjustment beam is projected in a time-sharing manner to each pixel position of an image corresponding to the video signal. The control method of a projection type image display apparatus which has a control step which changes the optical path length of the said light beam by controlling the said adjustment means based on this. In the control method of the projection type image display device according to claim 11,
The method of controlling a projection type image display apparatus, wherein, in the control step, the optical path length is changed so that the plurality of adjustment beams are projected in a time-division manner within a drawing time for drawing each pixel of the image. In the control method of the projection type image display device according to claim 11,
The method of controlling a projection type image display apparatus, wherein, in the control step, the optical path length is changed at a speed that is an integer multiple of 1 or more excluding a multiple of the number of the adjustment beams of the frame rate of the video signal.

Images