JP2008287149A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive image display device capable of suppressing the distortion of an image to be displayed on a face to be projected (a screen). <P>SOLUTION: The image display device is characterized by comprising: a light source 10 which emits a beam light; first scanning parts 30 and 20 which have a non-constant speed scanning part 30 which scans the beam light at a non-constant speed in at least one direction of the horizontal direction and the vertical direction of the face to be projected 40; and a correction part 26 which corrects the radiation position of the beam light scanned by the first scanning parts 30 and 21 on the screen 40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image display device.

  2. Description of the Related Art In recent years, scanning image display apparatuses that display an image by raster scanning beam-like light such as laser light on a projection surface have been proposed. In this apparatus, since the complete black can be expressed by stopping the supply of the laser light, a high contrast display is possible as compared with, for example, a projector using a liquid crystal light valve. In addition, image display devices that use laser light have characteristics such as high color purity because the laser light has a single wavelength and high coherence, so that the beam is easy to shape (easy to squeeze). It is expected as a high-quality display that realizes resolution and high color reproducibility. In addition, unlike a liquid crystal display, a plasma display, or the like, a scanning image display device does not have a fixed pixel, and therefore has an advantage that the resolution is easily converted without the concept of the number of pixels.

In order to generate an image with a scanning image display device, it is necessary to scan light two-dimensionally using a scanner such as a polygon mirror or a galvanometer mirror. There is a method of scanning light two-dimensionally while swinging one scanner in two directions, the horizontal direction and the vertical direction, but in this case, there is a problem that the configuration and control of the scanning system become complicated. In view of this, a scanning type image display apparatus has been proposed in which two sets of scanners for scanning light in one dimension are prepared, and each of them has a horizontal scanning and a vertical scanning. Conventionally, both scanners normally use a polygon mirror or a galvanometer mirror, and a projection apparatus using a rotating polygon mirror (polygon mirror) for both scanners is disclosed in Patent Document 1 below.
JP-A-1-245780

  However, in Patent Document 1, an apparatus using a polygon mirror is introduced. However, as the resolution of an image format is increased, the scanning frequency is also increasing, and the polygon mirror and the galvanometer mirror are reaching their limits. Therefore, in recent years, a system using MEMS (Micro Electro Mechanical Systems) technology for a high-speed scanner has been announced. A scanner using MEMS technology (hereinafter simply referred to as a MEMS scanner) is manufactured using a microfabrication technology of a semiconductor material such as silicon, and drives a mirror supported by a torsion spring or the like by electrostatic force or the like. It is. This scanner can scan the light by reciprocating the mirror by the interaction between the electrostatic force and the restoring force of the spring. By using the MEMS scanner, it is possible to realize a scanner having a high frequency and a large deflection angle as compared with a conventional scanner. This makes it possible to display a high-resolution image.

In order to realize a high-speed MEMS scanner, it is necessary to reciprocate the mirror at the resonance point. Therefore, it is difficult to operate the light scanned by the MEMS scanner at a constant speed from end to end of the projection surface. Thereby, the image projected on the projection surface is distorted.
Accordingly, examples of means for scanning the light beam at a sufficiently high speed and at a constant speed include a scanner using an acousto-optic element or an electro-optic element. However, these scanners have a problem that it is difficult to obtain a sufficiently large declination compared to a MEMS scanner, and it is difficult to construct a practical image display device.
A method of correcting the distortion of the laser light projected on the projection surface by arranging an optical element is also conceivable. However, this configuration makes the structure complicated and makes it difficult to adjust the optical axis. Soaring is also possible.

  SUMMARY An advantage of some aspects of the invention is that it provides an image display device capable of suppressing distortion of an image displayed on a projection surface at low cost.

In order to achieve the above object, the present invention provides the following means.
An image display device of the present invention includes a light source that emits beam-shaped light, and a non-constant speed scanning unit that scans the beam-shaped light at a non-constant speed in at least one of a horizontal direction and a vertical direction of a projection surface. And a correction unit that corrects an irradiation position of the beam-shaped light scanned by the first scanning unit on the projection surface.

In the image display device according to the present invention, the beam-like light emitted from the light source is scanned from the horizontal end of the projection surface to the opposite end by the first scanning unit. Here, since the non-constant speed scanning part of the first scanning part is non-constant speed, for example, the end of the projection surface becomes a turning point and the speed becomes zero, so that the scanned light is projected. The speed of the first scanning unit decreases as it goes toward the end of the surface. As a result, the beam-like light scanned by the first scanning unit is distorted on the end side of the projection surface, and thus deviates from a predetermined position. Therefore, in the present invention, since the correction unit is provided, the correction unit corrects the position of the beam-like light on the projection surface scanned by the first scanning unit, so that the beam-like shape is accurately positioned. Can be scanned. Therefore, since the beam-shaped light scanned on the projection surface is corrected so as to draw a straight line, the beam-shaped light can be scanned with high accuracy on the projection surface. That is, when the image display device is used as an image display device, a clear image can be displayed.
In the present invention, since the correction unit may be disposed on the optical path of the beam-like light emitted from the light source, the optical axis is compared with the case where the beam-like light is corrected using an optical element such as a lens. Since alignment is not necessary, it is possible to reduce the manufacturing cost.
Here, “horizontal scanning” refers to high-speed scanning of the two scanning directions, and “vertical scanning” refers to low-speed scanning.

  In the image display device of the present invention, it is preferable that the correction unit corrects the beam-like light in the vertical direction.

  In the image display device according to the present invention, the correction unit corrects the irradiation position on the projection surface scanned by the first scanning unit in the vertical direction. Here, the beam-like light is also scanned in the vertical direction of the projection surface by the first scanning unit, and the scanning speed of the first scanning unit becomes slower toward the end side of the projection surface. The beam-like light is shifted from the predetermined position in the vertical direction. At this time, since the correction unit corrects the beam-like light in the vertical direction, the vertical shift of the beam-like light can be corrected.

  In the image display device of the present invention, it is preferable that the correction unit corrects the beam-like light in the horizontal direction.

  In the image display device according to the present invention, since the first scanning unit reciprocates, the scanning speed of the first scanning unit decreases toward the end of the projection surface. The pitch changes. That is, the pixel pitch is large (pixel density is low) on the center side of the projection surface, and the pixel pitch is small (pixel density is high) on the end portion side of the projection surface. As a result, the image projected on the projection surface is distorted and the brightness is non-uniform. Therefore, in the image display device according to the present invention, since the correction unit corrects the beam-like light in the horizontal direction, the pixel density can be made uniform, so that the image distortion is corrected and the luminance is made uniform. Is possible.

  In the image display device according to the aspect of the invention, the correction unit corrects the beam-shaped light in the vertical direction, and a horizontal correction optical device corrects the beam-shaped light in the horizontal direction. It is preferable to provide an element.

  In the image display device according to the present invention, the vertical correction optical element and the horizontal correction optical element are arranged in series on the optical path of the beam-like light emitted from the light source, so that the vertical direction and the horizontal direction of the projection surface are aligned. Image distortion can be corrected.

  In the image display device of the present invention, the correction unit is arranged on an optical path between the light source and the first scanning unit, and corrects the beam-shaped light incident on the first scanning unit. preferable.

In the image display device according to the present invention, the correction unit is disposed in the optical path between the light source and the first scanning unit, and thus corrects the scanning of the beam-shaped light before being scanned by the first scanning unit. . Accordingly, since the beam-like light emitted from the correction unit can have a small swing angle, the correction unit can be sufficiently corrected by low voltage driving.
Further, since the correction unit needs only a small swing angle, an optical element having a smaller size than the first scanning unit may be used. Therefore, it is possible to reduce the size of the entire apparatus.

  In the image display device of the present invention, the correction unit is arranged on an optical path between the first scanning unit and the projection surface, and corrects the beam-like light emitted from the first scanning unit. preferable.

  In the image display device according to the present invention, since the correction unit is disposed in the optical path between the first scanning unit and the projection surface, the beam-shaped light is scanned after being scanned by the first scanning unit. to correct. For example, in order to make the beam-like light emitted from the first scanning unit and scanned onto the projection surface enter as perpendicular as possible, the diameter of the beam-like light may be reduced using a stop. In the case of this configuration, when an optical element is used as the correction unit, the thickness of the correction unit can be reduced because the thickness can be such that beam-like light can enter. As a result, the correction unit can be driven with a low voltage, so that power consumption can be reduced.

  In the image display device according to the aspect of the invention, it is preferable that the correction unit corrects a positional deviation on the projection surface scanned by the first scanning unit.

  In the image display device according to the present invention, since the correction unit corrects the positional deviation on the projection surface scanned by the first scanning unit, it is possible to suppress luminance unevenness on the projection surface.

  In the image display device according to the aspect of the invention, it is preferable that the correction unit corrects distortion of an image on the projection surface formed by the first scanning unit.

  In the image display device according to the present invention, since the correction unit corrects the distortion of the image on the projection surface formed by the first scanning unit, a clear image can be displayed on the projection surface.

  In the image display device of the present invention, it is preferable that the non-constant speed scanning unit is a MEMS mirror.

  In the image display apparatus according to the present invention, the beam-like light emitted from the light source is scanned toward the projection surface by the MEMS mirror. Thus, by using the MEMS mirror as the first scanning unit, the entire apparatus can be reduced in size. Furthermore, it is possible to obtain effects such as low power consumption, quietness, and low vibration of the entire apparatus as compared with the case where other mirrors are used.

In the image display device of the present invention, it is preferable that the correction unit includes an acousto-optic element.
In the image display device according to the aspect of the invention, it is preferable that the correction unit includes an electro-optical element.

  In these image display apparatuses according to the present invention, the position of the beam-like light emitted from the light source on the projection surface is corrected by the acousto-optic element or the electro-optic element. As described above, by using an acousto-optic element or an electro-optic element as the correction unit, it is possible to deflect the beam-like light at a minute angle with high accuracy.

  Hereinafter, an embodiment of an image display device 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]
The image display apparatus 1 according to the present embodiment is an image display apparatus that projects an image on a screen using light sources of three colors.

As shown in FIG. 1, the image display device 1 according to the present embodiment includes a light source unit 10, a cross dichroic prism 11, a correction optical element (correction unit) 26, and a MEMS mirror (first scanning unit: unequal). A high-speed scanning unit) 30 and a MEMS mirror (first scanning unit) 20.
The light source unit 10 emits a red light source device (light source) 10R that emits red laser light (beam-like light, center wavelength: 620 nm) and a green laser light (beam-like light, center wavelength: 530 nm). It has a green light source device (light source) 10G and a blue light source device (light source) 10B that emits blue laser light (beam-like light, center wavelength: 460 nm). Note that the wavelengths of red, green, and blue laser light are merely examples.
The cross dichroic prism 11 combines the laser beams of the respective colors emitted from the light source devices 10R, 10G, and 10B.

First, as shown in FIG. 1, the MEMS mirror 20 is a vertical scanning unit that scans laser light emitted from the MEMS mirror 30 in the vertical direction v out of scanning in two directions (vertical direction v and horizontal direction h) on the screen 40. The MEMS mirror 30 is a horizontal scanning scanner that scans light emitted from the correction optical element 26 in the horizontal direction h.
The correction optical element 26 is an element that scans the laser light incident on the MEMS mirror 30 and corrects the position of the laser light on the screen 40.
The “horizontal scanning scanner” mentioned here is a scanner responsible for high-speed scanning out of two directions, and the “vertical scanning scanner” is a scanner responsible for low-speed scanning.
The screen 40 used in the present embodiment is a so-called VGA (Video Graphics Array) type display formed by pixels of horizontal 640 × vertical 480.
The “pixel” referred to here is an irradiation area on the projection surface corresponding to one pixel which is a minimum unit constituting the projection image.

The correcting optical element 26 is a dielectric crystal (electro-optic crystal) having an electro-optic effect, and in this embodiment, a crystal material having a composition of KTN (potassium niobate tantalate, KTa _1-x Nb _x O ₃ ). It consists of The KTN crystal is a crystal utilizing the Kerr effect (a phenomenon in which birefringence occurs when an electric field is applied to an isotropic material, and is proportional to the square of the strength of an electric field generated by an applied voltage).

  As shown in FIG. 1, the correction optical element 26 includes an optical element 21, a first electrode 22, and a second electrode 23. The optical element 21 has a rectangular parallelepiped shape. The first electrode 22 is disposed on the upper surface 21a of the optical element 21, and the second electrode 23 is disposed on the lower surface 21b. A power source (not shown) for applying a voltage is connected to the first electrode 22 and the second electrode 23. Further, as shown in FIG. 1, the first electrode 22 and the second electrode 23 have substantially the same size in the traveling direction of the laser light L traveling in the optical element 21. As a result, an electric field is generated in the optical element 21 between the first electrode 22 and the second electrode 23. For example, when a voltage higher than the second electrode 23 is applied to the first electrode 22, an electric field is generated from the first electrode 22 toward the second electrode 23 (in the direction indicated by arrow A). As a result, the refractive index of the electro-optic crystal increases from the first electrode 22 toward the second electrode 23. Conversely, when a voltage higher than the first electrode 22 is applied to the second electrode 23, an electric field is generated from the second electrode 23 toward the first electrode 22 (in the direction indicated by arrow B).

In the present embodiment, as will be described later, the positive and negative voltages shown in FIG. 2 are applied to the correction optical element 26, so that electric fields are generated in the directions of arrows A and B. The correcting optical element 26 corrects the laser beam in the vertical direction.
The correcting optical element 26 emits the laser light so that the frequency of scanning the laser light in the vertical direction is higher than the frequency of scanning the laser light of the MEMS mirror 20 and the MEMS mirror 30 in the vertical and horizontal directions. Scanning is possible. That is, the correction optical element 26 can be scanned at a higher speed than the MEMS mirror 20 and the MEMS mirror 30.

The MEMS mirror 30 is a mirror that scans the laser light emitted from the correction optical element 26 in the horizontal direction of the screen 40. Further, the MEMS mirror 30 includes a mirror part 31, beams 32a and 32b, and a first substrate 35 as shown in FIG.
The mirror unit 31 is provided at the center of the MEMS mirror 30 and reflects incident laser light to the screen 40. The beams 32 a and 32 b extend outward on both sides of the mirror portion 31 and are provided in the vertical direction (y-axis direction) of the screen 40. Thereby, the mirror unit 31 can vibrate in the y-axis, that is, can scan the laser beam in the horizontal direction of the screen 40.
In the MEMS mirror 20, beams 32a and 32b extend outward on both sides of the mirror portion 31, and are provided in the left-right direction (x-axis direction) of the screen 40. As a result, the mirror unit 31 can vibrate in the x-axis, that is, can scan the laser beam in the direction perpendicular to the screen 40. Other configurations are the same as those of the MEMS mirror 30.

Next, correction of laser light scanned on the screen 40 will be described with reference to FIG.
FIG. 4 is a diagram for explaining the locus of laser light when the laser light emitted from the light source unit 10 is scanned toward the screen 40 by the MEMS mirror 30 without using the correction optical element 26.
Since the MEMS mirror 30 reciprocates the mirror unit 31 at the resonance point, the MEMS mirror 30 scans the laser beam at a non-constant speed. Specifically, the scanning speed of the laser light drawn on the screen 40 is slow on the left end 40a and right end 40b sides of the screen 40 in the horizontal direction. Further, the MEMS mirror 20 scans the laser beam in the vertical direction at a constant speed while the MEMS mirror 30 scans the laser beam in the horizontal direction from the upper end 40 c to the lower end 40 d of the screen 40. Thereby, the laser beam scanned on the screen 40 draws a sine wave shape (broken line in FIG. 4) as shown in FIG.
Further, when the MEMS mirror 30 moves at a constant speed, a straight line (a chain line in FIG. 4) is drawn as shown in FIG.

When the MEMS mirror 30 moves at a constant speed, although it draws a straight line, it is scanned in an oblique direction of the screen 40, so that distortion occurs.
Therefore, the voltage applied to the correction optical element 26 so that the laser beam scanned in the horizontal direction by the MEMS mirror 30 is scanned in a horizontal line (predetermined position: solid line shown in FIG. 4). To control. FIG. 2 shows a correction voltage waveform applied to the correction optical element 26. The vertical axis of the MEMS mirror 30 is the scanning angle, the horizontal axis indicates the position on the screen 40, the vertical axis of the correction optical element 26 is the voltage, and the horizontal axis indicates time.
When the scanning angle of the MEMS mirror 30 is 0, the laser beam scans the central portion of the screen 40 in the horizontal direction. When the scanning angle is maximum, the left end 40a of the screen 40 is scanned and the scanning angle is reversed. When the maximum is to the side, the right end 40b of the screen 40 is scanned.

First, a case where laser light is scanned from the left end 40a of the screen 40 toward the right end 40b will be described.
From the left end 40a to the center of the screen 40, as shown in FIG. 4, the laser beam scans the upper end 40c side of the screen 40 from a predetermined position (solid line in FIG. 4). For this reason, the correction optical element 26 deflects the laser light toward the lower end 40d side of the screen 40 to the center of the screen 40 as indicated by an arrow M in FIG. Specifically, as shown in FIG. 2, a voltage pattern S1 that draws a curve is applied to the correction optical element 26 so that the voltage gradually decreases from a high voltage.
Then, from the center of the screen 40 to the right end 40b, the laser beam scans the lower end 40d side of the screen 40 from a predetermined position (solid line in FIG. 4) as shown in FIG. Therefore, the correcting optical element 26 deflects the laser light toward the upper end 40c side of the screen as indicated by an arrow N in FIG. Specifically, as shown in FIG. 2, a voltage pattern S2 that draws a curve so as to gradually increase from a low voltage to a high voltage is applied to the correction optical element 26.

Next, a case where laser light is scanned from the right end 40b of the screen 40 toward the left end 40a will be described.
As shown in FIG. 4, the laser light scans the upper end 40 c side of the screen 40 on the right end 40 b side of the screen 40, and thus a voltage having the same waveform as the voltage pattern S <b> 1 is applied. On the left end 40a side of the screen 40, a voltage having the same waveform as that of the voltage pattern S2 is applied to scan the lower end 40d side of the screen 40.
Then, by continuously applying the voltage pattern S1 and the voltage pattern S2 to the correcting optical element 26 and correcting the laser light in the vertical direction, the laser light draws a solid line from the chain line as shown in FIG. That is, the laser beam is scanned in the horizontal direction on the screen 40 as indicated by the solid line in FIG. 4 without being bent in the vertical direction.

Further, the screen 40 used in this embodiment is a VGA type, and when the maximum scanning angle in the vertical direction of the correction optical element 26 is 30 degrees, the scanning line interval is about 1 mrad. The correcting optical element 26 needs to be scanned ± 0.5 mrad in the vertical direction. If the scanning angle is about this level, scanning can be performed by applying a voltage of 10 V or less to the correcting optical element 26. That is, it is possible to scan sufficiently without increasing the voltage so much.
Even if the scanning angle is shifted in front of the MEMS mirror 30, the amount of deviation is very small, and the amount of deviation can be sufficiently swallowed by the MEMS mirror 30, so that horizontal scanning can be performed without hindrance.

In the image display device 1 according to the present embodiment, the correction optical element 26 corrects the laser light scanned on the screen 40 so as to be a straight line in the horizontal direction, so that the image is not distorted. That is, a clear image can be displayed on the screen 40.
Further, since the correcting optical element 26 may be disposed on the optical path of the laser light emitted from the cross dichroic prism 11, the optical element 26 is lighter than the case of correcting the locus of the laser light using an optical element, for example, a lens. Since it is not necessary to align the axes, the manufacturing cost can be reduced.
That is, the image display device 1 of the present embodiment can suppress distortion of an image displayed on the screen 40 at low cost.

Further, since the correcting optical element 26 is disposed in the optical path between the cross dichroic prism 11 and the MEMS mirror 30, it controls the scanning of the laser light before being scanned by the MEMS mirror 30. Accordingly, since the laser light emitted from the correction optical element 26 can have a small swing angle, the correction optical element 26 can be sufficiently corrected by driving at a low voltage.
Further, since the correction optical element 26 needs only a small swing angle, a small optical element may be used. Therefore, it is possible to reduce the size of the entire apparatus.

Although the correction optical element 26 is disposed in the optical path between the cross dichroic prism 11 and the MEMS mirror 30, the image display device is disposed in the optical path between the MEMS mirror 30 and the screen 40 as shown in FIG. 45 may be sufficient. For example, in order to make the laser beam emitted from the MEMS mirror 30 and scanned onto the screen 40 as perpendicular as possible, the beam diameter of the laser beam may be reduced using a diaphragm. In the case of this configuration, the thickness of the correction optical element 26 can be reduced, so that the correction optical element 26 can be driven with a low voltage, so that power consumption can be reduced.
Although the MEMS mirror is used as a vertical scanning scanner that scans the laser beam in the vertical direction v, a polygon mirror, a galvanometer mirror, or an electro-optical element may be used.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIGS. In the drawings of the respective embodiments described below, portions having the same configuration as those of the image display device 1 according to the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
The image display device 50 according to the present embodiment is different from the first embodiment in that the correction optical element 57 corrects the scanning of the laser beam in the horizontal direction. Other configurations are the same as those of the first embodiment.

  As shown in FIG. 6, the correction optical element 57 has the first electrode 22 such that the electric field direction A and the electric field direction B are generated in directions orthogonal to the electric field direction A and the electric field direction B of the correction optical element 26. And the 2nd electrode 23 is arrange | positioned. The correcting optical element 57 is an element that scans the laser light emitted from the cross dichroic prism 11 in the horizontal direction and corrects the position of the laser light on the screen 40.

Next, correction of laser light scanned on the screen 40 will be described with reference to FIGS.
FIG. 7 is a diagram showing the outer shape of an image formed on the screen 40 when the laser light emitted from the light source unit 10 is scanned toward the screen 40 by the MEMS mirror 30 without using the correction optical element 57. is there. That is, as shown by the broken line in FIG. 7, the image is distorted toward the center on the left end 40 a and right end 40 b sides of the screen 40. Furthermore, as described above, the scanning speed of the laser light scanned by the MEMS mirror 30 becomes slow at the left end 40a and the right end 40b of the screen 40. As a result, the size of one pixel of laser light (solid line shown in FIG. 7) is the size of the pixel at about 1/4 in the horizontal direction of the screen 40 of the image at the center of the screen 40 and 3/4. Is larger than the size of this pixel (the dot-and-dash line shown in FIG. 7) (the pixel density is low), and is smaller on the left end 40a and right end 40b sides of the screen 40 (the pixel density is high).

First, correction of laser light scanned in the horizontal direction so that the size of the pixels is uniform in the horizontal direction of the screen 40 will be described.
That is, in order to make the sizes of the pixels uniform, the laser light may move at a constant speed in the horizontal direction on the screen 40. As a result, as shown in FIG. 8, the difference between the locus of the laser beam when the MEMS mirror 30 moves at a constant speed (solid line in FIG. 8) and the locus of the actual laser beam (broken line in FIG. 8) is interpolated. The voltage to be applied (the one-dot chain line in FIG. 8) may be applied to the correcting optical element 57. That is, as shown in FIG. 9, the laser light has a voltage change of 0 at the left end 40 a of the screen 40 and gradually increases to the negative side, and the voltage change becomes 0 again at the center of the screen 40. In addition, a negative voltage is applied from the left end 40a of the screen 40 toward the center of the screen 40. However, from the left end 40b of the screen 40 to the right end 40b of the screen 40, the reverse direction, that is, the positive direction so that the size of pixels is uniform. A voltage is applied. The voltage waveform is symmetrical with the voltage waveform applied from the left end 40 a of the screen 40 to the center of the screen 40.

  In the image display device 50 according to the present embodiment, the correction optical element 57 can make the pixel density in the horizontal direction uniform, so that distortion of the image on the screen 40 can be corrected.

[Modification of Second Embodiment]
In this modification, correction of image distortion on the left end 40a and right end 40b side of the screen 40 will be described.
Here, correction of the laser beam for scanning the central portion C in the vertical direction of the screen 40 shown in FIG. 7 will be described. In other words, in the central portion of the screen 40, the scanning distance on the screen 40 is shorter by the length P than the scanning distance on the upper end 40c side of the screen 40. A higher voltage is applied toward the left end 40a and the right end 40b of 40. Specifically, from the left end 40a of the screen 40 to the central portion in the horizontal direction of the screen 40, the voltage applied to the correction optical element 57 is gradually changed from a high voltage to a low voltage as shown in FIG. A voltage pattern S1 that draws a curve is applied. A voltage pattern S2 that draws a curve is applied from the center of the screen 40 to the right end 40b so that the voltage gradually increases from a low voltage.
Note that the inclination of the alternate long and short dash line shown in FIG. 10 (obtained by the ratio of the length P to the total length of the screen 40 in the horizontal direction) increases toward the center of the screen 40 in the vertical direction. As a result, a correction voltage is applied to the correction optical element 57 in accordance with this inclination, and the laser light scanning each line is scanned from the left end 40a to the right end 40b of the screen 40, and a rectangular image is displayed.

In the image display device according to the present embodiment, since the distortion of the image on the left end 40a side and the right end 40b side of the screen 40 can be corrected, a clear image with uniform brightness can be displayed on the screen 40. Become.
Note that it is also possible to apply the image distortion correction of this modification to the image display device of the second embodiment.

[Third Embodiment]
Next, a third embodiment according to the present invention will be described with reference to FIGS. 11 to 15. In the image display device 65 according to the present embodiment, the MEMS mirror 60 is biaxially vibrated with the first embodiment. Different. Other configurations are the same as those of the first embodiment.
Further, as shown in FIG. 11, the image display device 65 includes a light source unit 10, a correction optical element 26, and a MEMS mirror 60.

As shown in FIG. 12, the MEMS mirror 60 includes a mirror unit 61, beams 62a and 62b, a first substrate 63, beams 64a and 64b, and a second substrate 65.
The mirror unit 61 is provided in the center of the MEMS mirror 60 and reflects incident laser light to the screen 40. The beams 62a and 62b extend outward on both sides of the mirror portion 61, and are provided in the left-right direction (x-axis direction) of the screen 40.
The first substrate 63 has a frame shape surrounding the mirror unit 61 and is connected to the beams 62a and 62b. The beams 64a and 64b extend outward from the first substrate 63 and are provided in the vertical direction (y-axis direction) of the screen 40.
The second substrate 65 has a frame shape surrounding the first substrate 63 and is connected to the beams 64a and 64b.
As a result, the mirror unit 61 can vibrate with respect to the first substrate 63 with the beams 62 a and 62 b as vibration axes, and the first substrate 63 vibrates the beams 64 a and 64 b with respect to the second substrate 65. Oscillating motion is possible as an axis. Therefore, the mirror unit 61 can perform biaxial vibration of the x axis and the y axis, that is, can scan the laser beam in the horizontal direction and the vertical direction of the screen 40.

In this embodiment, since the MEMS mirror 60 scans the laser beam in the horizontal direction and the vertical direction of the screen 40, as shown in FIG. 13, an image is displayed on the left end 40a, right end 40b, upper end 40c, and lower end 40d side of the screen. Distorted. Therefore, in the present embodiment, the correction of the deviation of the horizontal locus shown in the first embodiment and the distortion of the upper end 40c and the lower end 40d of the screen are corrected.
Specifically, as shown in FIG. 14, the correcting optical element 26 has an arcuate voltage for correcting distortion in the vertical direction on the upper end 40c side of the screen 40 (the central portion of the screen 40 indicated by a broken line in FIG. 14). A correction voltage (solid line in FIG. 14) obtained by synthesizing the voltage waveform having the highest voltage value) and the voltage for correcting the sine wave shape of the first embodiment (the dashed line in FIG. 14) is applied.

In the image display device 65 according to the present embodiment, even when the MEMS mirror 60 is a biaxially vibrating mirror, image distortion can be corrected by controlling the voltage applied to the correction optical element 26.
In order to correct the vertical distortion on the lower end 40d side of the screen 40, a voltage symmetrical to the correction voltage on the upper end 40c side is applied to the correcting optical element 26. That is, as shown in FIG. 15, the voltage applied to the correction optical element 26 is an arcuate voltage (voltage waveform having the highest voltage value at the center of the screen 40 indicated by a broken line in FIG. 15), A correction voltage (solid line in FIG. 15) obtained by combining the voltage for correcting the sine wave shape of the embodiment (the dashed line in FIG. 15) is applied, and this correction voltage is applied to the correction optical element 26.

In the present embodiment, in order to correct the distortion of the left end 40a and the right end 40b of the screen 40, the correction optical element 57 used in the second embodiment is provided, thereby making it possible to correct the laser beam in the horizontal direction. . Therefore, when correcting both the horizontal scanning and the vertical scanning of the laser light, the horizontal correction optical element for correcting the horizontal direction on the optical path of the laser light emitted from the cross dichroic prism 11 and the vertical direction. The vertical correction optical elements to be corrected may be arranged in series. Thereby, the distortion of the image of the image displayed on the screen 40 in the horizontal direction and the vertical direction can be suppressed.
When two correction optical elements are used, a configuration in which the two correction optical elements are arranged in series on the optical path between the MEMS mirror 60 and the screen 40 may be used. 10 and the MEMS mirror 60 may be disposed on the optical path, and the other correction optical element may be disposed on the optical path between the MEMS mirror and the screen 40. Furthermore, the vertical correction optical element and the horizontal correction optical element may be either an acousto-optical element or an electro-optical element.
Further, when the laser beam can be scanned in the horizontal direction and the vertical direction with one correction optical element, it is not necessary to provide the correction optical element separately for horizontal and vertical use, so that the entire apparatus can be reduced in size. It becomes possible.

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, a KTN crystal (electro-optical element) is used as the correction unit, but the invention is not limited to this, and another electro-optical element (for example, lithium niobate; LiNbO ₃ ) may be used. Furthermore, it is not limited to an electro-optical element, but may be an acousto-optical element. By using an acousto-optic element or an electro-optic element as the correction unit, the laser beam can be deflected at a minute angle with high accuracy.
Although the MEMS mirror is used as the first scanning unit, any scanning mechanism that reciprocates may be used.

1 is a perspective view showing an image display device according to a first embodiment of the present invention. It is a figure which shows the waveform of the voltage applied to the correction | amendment part of FIG. It is a top view which shows the 1st scanning part of FIG. It is a figure which shows typically the laser beam scanned on the to-be-projected surface of FIG. It is a perspective view which shows the modification of the image display apparatus which concerns on 1st Embodiment of this invention. It is a perspective view which shows the image display apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows typically the laser beam scanned on the to-be-projected surface of FIG. It is explanatory drawing of the voltage applied to the correction | amendment part of FIG. It is a figure which shows the waveform of the voltage applied to the correction | amendment part of FIG. It is a figure which shows the waveform of the voltage applied to the correction | amendment part when scanning the center part of the to-be-projected surface of FIG. It is a perspective view which shows the image display apparatus which concerns on 3rd Embodiment of this invention. It is a top view which shows the 1st scanning part of FIG. It is a figure which shows typically the laser beam scanned on the to-be-projected surface of FIG. It is a figure which shows the voltage waveform applied to the correction | amendment part of FIG. It is a figure which shows the voltage waveform applied to the correction | amendment part of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,45,65 ... Image display apparatus, 10R ... Red light source device (light source), 10G ... Green light source device (light source), 10B ... Blue light source device (light source), 26,57 ... Correction optical element (correction part), 30, 60 ... MEMS mirror (first scanning unit), 40 ... Screen (projected surface)

Claims (11)

A light source that emits beam-shaped light;
A first scanning unit having a non-constant speed scanning unit that scans the beam-shaped light at a non-constant speed in at least one of a horizontal direction and a vertical direction of a projection surface;
An image display apparatus comprising: a correction unit that corrects an irradiation position on the projection surface of the beam-shaped light scanned by the first scanning unit.   The image display apparatus according to claim 1, wherein the correction unit corrects the beam-like light in the vertical direction.   The image display apparatus according to claim 1, wherein the correction unit corrects the beam-like light in the horizontal direction.   The correction unit includes a vertical correction optical element that corrects the beam-shaped light in the vertical direction and a horizontal correction optical element that corrects the beam-shaped light in the horizontal direction. Item 4. The image display device according to Item 1.   The said correction | amendment part is arrange | positioned on the optical path between the said light source and the said 1st scanning part, and correct | amends the beam-form light which injects into the said 1st scanning part. The image display device according to any one of the above.   The correction unit is disposed on an optical path between the first scanning unit and the projection surface, and corrects beam-like light emitted from the first scanning unit. The image display device according to any one of the above.   The image display apparatus according to claim 1, wherein the correction unit corrects a positional deviation on the projection surface scanned by the first scanning unit.   The image display device according to claim 1, wherein the correction unit corrects distortion of an image on the projection surface formed by the first scanning unit. .   The image display apparatus according to claim 1, wherein the non-constant speed scanning unit is a MEMS mirror.   The image display apparatus according to claim 1, wherein the correction unit includes an acousto-optic element.   The image display apparatus according to claim 1, wherein the correction unit includes an electro-optic element.

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