JP2007121538A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device that can display an image with high resolution with a simple configuration. <P>SOLUTION: The image display device displays an image by scanning an irradiation objective surface S with a beam light modulated according to image signals. The device is equipped with a light source unit 101G for supplying the beam light, a scanning unit for scanning the beam light from the light source unit 101G, and a condensing optical system LM1 for condensing the beam light, wherein the scanning unit is equipped with a reflecting mirror 202 for reflecting the beam light, and the condensing optical system LN1 forms a beam waist BW at a position farther from the reflecting mirror 202 than the middle position M between the reflecting mirror 202 and the irradiation objective surface S. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an image display apparatus, and more particularly to a technique of an image display apparatus that displays an image by scanning a light beam modulated in accordance with an image signal.

In recent years, a laser projector that displays an image by scanning laser light has been proposed as an image display device that displays an image. Laser light has features such as high color purity, high coherence, and easy shaping. Therefore, it is expected that a laser projector displays an image with high resolution and good color reproducibility. For scanning with laser light, a configuration in which light is scanned by vibrating a reflecting mirror in a state of reflecting light can be used. For example, Patent Document 1 proposes a technique for scanning a laser beam using a reflection mirror in a laser projector.

JP 2003-21800 A

In order to display a high-resolution image, laser light is scanned at a high speed in order to form many pixels in one frame period of the image. In order to drive the reflecting mirror at high speed and accurately, it is desirable to make the deflection angle of the reflecting mirror as small as possible. Therefore, particularly when displaying a large image, an irradiated surface such as a screen and the reflecting mirror There is a need to increase the distance between the two. If the optical system is configured such that the beam waist having the minimum beam diameter is the position of the reflecting mirror, it is conceivable that the spot of the laser beam formed on the irradiated surface is larger than one pixel. The longer the distance between the illuminated surface and the reflecting mirror,
The spot on the irradiated surface becomes larger as the laser beam is narrowed down by the beam waist. In this case, since it is necessary to add an optical system in order to fit a spot in one pixel, the optical system becomes complicated. In the configuration proposed in Patent Document 1,
A beam waist is formed at the position of the irradiated surface. In this case, since the beam diameter in the reflection mirror becomes large, it is necessary to use a large reflection mirror. When the reflecting mirror becomes large, it is very difficult to vibrate the reflecting mirror at a high speed and with a large deflection angle.

In order to avoid problems caused by forming a beam waist on either the irradiated surface or the reflecting mirror, it is conceivable to form a beam waist at an intermediate position between the irradiated surface and the reflecting mirror. However, in the case where an optical path of 1 m or more is secured from the reflecting mirror to the irradiated surface, the beam diameter of about 1 mm, for example, fits in the pixel or the reflecting mirror in the optical path from the irradiated surface to the reflecting mirror. It is very difficult to maintain. in this way,
In the conventional technique for displaying an image by scanning light beams, there is a problem that it is difficult to display an image with a high resolution with a simple configuration. The present invention has been made in view of the above-described problems, and an object thereof is to provide an image display apparatus capable of displaying a high-resolution image with a simple configuration.

In order to solve the above-described problems and achieve the object, according to the present invention, there is provided an image display device that displays an image by scanning a surface to be irradiated with a light beam modulated in accordance with an image signal. A light source unit that supplies the beam light, a scanning unit that scans the beam light from the light source unit, and a condensing optical system that condenses the beam light. It is possible to provide an image display device characterized by forming a beam waist at a position farther from the scanning unit than an intermediate position with respect to the surface.

When the beam weight is formed at a position farther from the scanning unit than the intermediate position between the scanning unit and the irradiated surface, the spot diameter on the irradiated surface is compared with the case where the beam waist is formed at the position of the scanning unit. Can be reduced. Compared with the case where a beam waist is formed at the position of the irradiated surface, the beam diameter at the scanning portion can be reduced. According to the present invention,
It is possible to optimize the position of the beam waist so that the spot is placed in the pixel area corresponding to the screen size and the resolution, and the beam diameter is minimized at the position of the scanning unit. By placing spots in the pixel area, high-definition display according to the resolution is possible. By minimizing the beam diameter at the position of the scanning unit, the size of the reflection mirror used in the scanning unit can be reduced. Since the reflection mirror can be made small, the reflection mirror can be vibrated at high speed and with a large deflection angle. Furthermore, since the present invention can be realized only by adjusting the position of the beam waist as appropriate, a new optical system is not required and a simple configuration can be achieved. Thereby, an image display device capable of displaying an image with a high resolution with a simple configuration can be obtained.

According to a preferred aspect of the present invention, it is desirable that the condensing optical system forms a beam waist in the optical path between the intermediate position and the irradiated surface. As a result, spots can be accommodated in the pixel region, and the beam diameter at the position of the scanning unit can be reduced.

Moreover, according to the preferable aspect of this invention, the 1st condensing optical system which is provided between the light source part and the scanning part and condenses the beam light from a light source part in a scanning part, a scanning part, and to-be-irradiated And a second condensing optical system that forms a beam waist by condensing the beam light from the first condensing optical system. The first condensing optical system condenses the beam light so that the beam diameter becomes sufficiently small by the reflection mirror of the scanning unit. Compared to the case of using only the second condensing optical system provided between the scanning unit and the irradiated surface, the beam diameter at the position of the scanning unit is reduced by using the first condensing optical system together. It becomes possible to do. Thereby, the beam diameter at the position of the scanning unit can be further reduced and the beam waist can be set at an optimum position.

Moreover, as a preferable aspect of the present invention, a beam diameter adjusting optical system that adjusts the beam diameter of the beam light is provided between the scanning unit and the second light collecting optical system. It is desirable to collect the beam light from the beam diameter adjusting optical system. The laser light after being condensed near the scanning unit by the first condensing optical system is incident on the second condensing optical system. In order to make the beam light that has returned to a predetermined beam diameter after being condensed by the first condensing optical system enter the second condensing optical system, the distance between the scanning unit and the second condensing optical system is increased. It will be. In order to capture the scanning beam light with the second condensing optical system, a larger second condensing optical system is required as the distance between the scanning unit and the second condensing optical system becomes longer. By adopting a configuration in which the beam diameter can be appropriately adjusted by the beam diameter adjusting optical system, it is not necessary to increase the distance between the scanning unit and the second condensing optical system. Also,
By enabling the second condensing optical system to be disposed at a position close to the scanning unit, a small second condensing optical system can be used. Thus, by appropriately adjusting the beam diameter according to the configuration of the optical system,
The degree of freedom of the configuration of the optical system can be increased.

Moreover, as a preferable aspect of the present invention, it is desirable that the scanning unit includes a reflection mirror that reflects the beam light, and the beam light is scanned by causing the reflection mirror to resonate. By causing the reflecting mirror to resonate, the amount of displacement of the reflecting mirror can be increased. Thereby, the laser beam can be efficiently scanned with a small amount of energy. In the present invention, it is possible to use a reflection mirror that is small and can be resonated.

As a preferred embodiment of the present invention, the light source unit supplies beam light that is a plurality of color lights having different peak wavelengths, and the condensing optical system is provided for each color light and corresponds to the peak wavelength. It is desirable to form a beam waist at the position. The beam light tends to spread as the wavelength increases. By using a condensing optical system that forms a beam waist at a position corresponding to the peak wavelength, the spot size of each color light on the irradiated surface can be made uniform. Thereby, color shift can be reduced and a high quality image can be displayed.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of an image display apparatus 100 according to Embodiment 1 of the present invention. The image display device 100 is a so-called rear projector that supplies laser light to one surface of the screen 110 and observes an image by observing light emitted from the other surface of the screen 110. The image display apparatus 100 displays an image by causing the light beam modulated according to the image signal to scan on the irradiated surface S of the screen 110.

The image display apparatus 100 includes an R light source unit 101R, a G light source unit 101G, and a B light source unit 101B. The R light source unit 101R is a semiconductor laser that supplies red laser light (hereinafter referred to as “R light”) that is beam light. The G light source unit 101G is a semiconductor laser that supplies green laser light (hereinafter referred to as “G light”), which is beam light. The light source unit 101B for B light is a semiconductor laser that supplies blue laser light (hereinafter referred to as “B light”) that is beam light. Each of the color light source units 101R, 101G, and 101B supplies laser light that is modulated according to an image signal and has different peak wavelengths. As the modulation according to the image signal, either amplitude modulation or pulse width modulation may be used.

The condensing optical system LN1 includes a light source unit for R light 101R and a cross dichroic prism 103, a light source unit for G light 101G and a cross dichroic prism 103, and a light source unit for B light 101B and a cross dichroic prism 103. Each is provided in between. Thus, the condensing optical system LN1 is provided for each color light. The condensing optical system LN1 condenses each laser beam. The condensing optical system LN1 is not limited to being configured by a single lens, and may be configured by a plurality of lenses. Each color light source 101R, 101
The light from G and 101B passes through the condensing optical system LN1 and then enters the cross dichroic prism 103.

The cross dichroic prism 103 includes two dichroic films 103a and 103b.
Have The first dichroic film 103a and the second dichroic film 103b are arranged orthogonal to the X shape. The R light from the R light source 101R is emitted from the first dichroic film 1
Reflecting at 03a and transmitting through the second dichroic film 103b, the scanning unit 20
Proceed in the direction of zero. The G light from the G light source 101G is emitted from the first dichroic film 103.
The light travels in the direction of the scanning unit 200 by passing through a and the second dichroic film 103b. The B light from the B light source unit 101B is reflected by the second dichroic film 103b and passes through the first dichroic film 103a, thereby traveling toward the scanning unit 200. Thus, the cross dichroic prism 103 combines the R light, the G light, and the B light.

FIG. 2 shows a schematic configuration of the scanning unit 200. The scanning unit 200 has a so-called double gimbal structure having a reflection mirror 202 and an outer frame portion 204 provided around the reflection mirror 202. The outer frame portion 204 is connected to a fixed portion (not shown) by a first torsion spring 206 that is a rotation shaft. The outer frame portion 204 rotates around the first torsion spring 206 by utilizing the twist of the first torsion spring 206 and the restoration to the original state. The reflection mirror 202 is a second torsion spring 2 that is a rotation axis substantially orthogonal to the first torsion spring 206.
07 is connected to the outer frame portion 204. The reflection mirror 202 is a light source unit 1 for each color light.
The laser beams from 01R, 101G, and 101B are reflected. The reflection mirror 202 can be configured by forming a highly reflective member, for example, a metal thin film such as aluminum or silver. The reflection mirror 202 has a square shape, for example.

The reflecting mirror 202 is displaced so that the laser beam is scanned in the Y direction (see FIG. 1) on the screen 110 when the outer frame portion 204 rotates about the first torsion spring 206. In addition, the reflection mirror 202 rotates around the second torsion spring 207 using the twist of the second torsion spring 207 and the restoration to the original state. Reflective mirror 2
02 is rotated around the second torsion spring 207, thereby reflecting the mirror 202.
The laser beam reflected by is displaced so as to scan in the X direction. Thus, the scanning unit 200
Laser light from each color light source unit 101R, 101G, 101B is repeatedly scanned in the X and Y directions.

FIG. 3 illustrates a configuration for driving the scanning unit 200. Reflection mirror 20
When the side 2 reflects the laser beam is the front side, the first electrodes 301 and 302 are formed of the outer frame portion 204.
Are provided at substantially symmetrical positions with respect to the first torsion spring 206. When a voltage is applied to the first electrodes 301 and 302, the first electrodes 301 and 302,
A predetermined force corresponding to the potential difference, for example, an electrostatic force, is generated between the outer frame portion 204 and the outer frame portion 204. Outer frame 2
04 rotates about the first torsion spring 206 by alternately applying a voltage to the first electrodes 301 and 302.

Specifically, the second torsion spring 207 includes a third torsion spring 307 and a fourth torsion spring 308. Third torsion spring 307 and fourth torsion spring 308
A mirror-side electrode 305 is provided between the two. A second electrode 306 is provided in the space behind the mirror side electrode 305. When a voltage is applied to the second electrode 306, the second electrode 3
A predetermined force corresponding to the potential difference, for example, an electrostatic force, is generated between 06 and the mirror side electrode 305. When a voltage having the same phase is applied to any of the second electrodes 306, the reflection mirror 202 is
It rotates around the torsion spring 207. The scanning unit 200 rotates the reflection mirror 202 in this way, thereby scanning the laser light in the two-dimensional direction. The scanning unit 200 can be created by, for example, MEMS (Micro Electro Mechanical Systems) technology.

For example, the scanning unit 200 moves 1 in the Y direction which is the sub-scanning direction in one frame period of the image.
While scanning the laser beam twice, the reflection mirror 202 is displaced so as to reciprocate the laser beam a plurality of times in the X direction which is the main scanning direction. Assuming that the X direction is the first direction and the Y direction is the second direction substantially orthogonal to the first direction, the scanning unit 200 has a frequency at which the laser beam is scanned in the first direction. Driven to be higher than the frequency of scanning light. In order to scan the laser beam in the X direction at high speed, it is desirable that the scanning unit 200 be configured to resonate the reflecting mirror 202 around the second torsion spring 207. By causing the reflection mirror 202 to resonate, the amount of displacement of the reflection mirror 202 can be increased. By increasing the amount of displacement of the reflection mirror 202, the scanning unit 200 can efficiently scan the laser beam with less energy. The reflection mirror 202 is
It may be driven by an operation other than the resonance operation.

The scanning unit 200 is not limited to the configuration driven by the electrostatic force corresponding to the potential difference. For example,
A configuration in which the piezoelectric element is driven by using an expansion / contraction force or electromagnetic force may be used. The scanning unit 200 may include a reflection mirror that scans the laser light in the X direction and a reflection mirror that scans the laser light in the Y direction. Furthermore, the scanning unit 200 is not limited to a configuration using a galvanometer mirror,
You may use the polygon mirror which rotates the rotary body which has a some mirror piece.

Returning to FIG. 1, the light from the scanning unit 200 enters the reflecting unit 105. The reflector 105 is
The laser beam from the scanning unit 200 is reflected in the direction of the screen 110. The screen 110 is provided on the front surface of the housing 107. The housing 107 seals the space inside the housing 107. The screen 110 is a transmissive screen that transmits laser light modulated in accordance with an image signal. The screen 110 includes, for example, a Fresnel lens that converts the angle of light toward the viewer, a lenticular lens that diffuses light (both not shown), and the like. The observer
The image is viewed by observing the light emitted from the screen 110.

FIG. 4 shows the spot SP of the laser beam formed on the irradiated surface S of the screen 110 and the pixel P displayed by scanning the laser beam. The pixel P has a square shape with a side length d. The spot SP has a circular shape with a radius ω _P. The radius ω _P is the beam radius of the laser light on the irradiated surface S. In this specification, the beam radius refers to a Gaussian beam radius. If the beam radius ω _P is equal to or less than d / 2, the spot SP can be contained in the region of the pixel P. The image display apparatus 100 can perform high-definition display according to the resolution by placing the spot SP in the region of the pixel P.

For example, 1920 × on a screen 110 having a screen size of 50 inches diagonally.
Consider the case of displaying a full high-definition image of 1080 pixels. In this case, the length d of one side of one pixel P is approximately 0.5765 mm. When forming a spot SP in which the laser light just fits in the region of the pixel P, the beam radius ω of the laser light on the irradiated surface S
_P is 0.5765 / 2≈0.288 (mm).

FIG. 5 illustrates a conventional configuration for forming a laser beam beam waist on the surface S to be irradiated. The beam waist is a position where the wavefront curvature is zero and the beam diameter is minimum in a Gaussian beam. Here, the light path of G light among each color light will be described as a representative example. For the sake of convenience, the optical path from the G light source 101G to the screen 110 is shown as being on a single straight line, and illustrations of components unnecessary for the description are omitted. The beam radius ω (z) of the Gaussian beam at a position z from the position of the beam waist is expressed by the following equation (1
).

Where λ is the wavelength of the light beam, M ² is the beam quality, and ω ₀ is the beam radius at the beam waist. The beam quality M ² represents a ratio obtained by dividing an actual beam light divergence angle by an ideal diffraction limited beam divergence angle. The beam quality M ² is represented by a numerical value of 1 or more.

For example, consider the case where the distance L ₀ from the reflecting mirror 202 to the irradiated surface S is 1.5 m in the configuration shown in FIG. Since a beam waist is formed at the position of the irradiated surface S,
The beam radius ω ₀ = ω _P = 0.288 mm at the beam waist. Assuming that the peak wavelength λ of G light is 550 nm and the beam quality M ² is 1.0, the beam radius ω _{S at} the position of the reflecting mirror 202 is substituted with z = 1.5 × 10 ³ in the equation (1). Can be calculated.
ω _S = ω (1.5 × 10 ³ ) ≒ 0.956mm

Therefore, when the beam waist is formed at the position of the irradiated surface S, one side is 2 × 0.956 =
It is sufficient to prepare the reflection mirror 202 that is 1.912 (mm) or more.

FIG. 6 illustrates the structure of the characteristic part of the image display apparatus 100 of the present embodiment. The image display apparatus 100 is characterized in that a beam waist BW is formed in the optical path between the intermediate position M between the reflection mirror 202 and the irradiated surface S and the irradiated surface S by the condensing optical system LN1. The beam waist BW is formed at a position where the distance from the irradiated surface S is L ₁ . It is assumed that the distance L ₀ from the reflecting mirror 202 to the irradiated surface S is 1.5 m, the wavelength λ, and the beam quality M ² are the same as those described in FIG.

When the beam radius ω _P at the position of the irradiated surface S is 0.288 mm, the distance L ₁ between the irradiated surface S and the beam waist BW and the beam at the position of the reflecting mirror 202 are calculated using the above equation (1). The relationship with the radius ω _S can be expressed as shown in FIG. From the relationship shown in FIG. 7, it can be seen that when the beam waist BW is formed at the position of the distance L ₁ = 136.507 mm from the irradiated surface S, the beam radius ω _{S at} the position of the reflecting mirror 202 is minimized.
Note that the discontinuity of the graph at a portion where L ₁ is near 237 mm indicates that there is no state that satisfies the condition when L ₁ is 237 mm or more.

The beam radius ω _{S at} the position of the reflecting mirror 202 is expressed by z = 1.5 × 10 ^{3 in the} above equation (1).
It can be calculated by substituting −136.507.
ω _S = ω (1.5 × 10 ³ −136.507) ≈0.911 mm

Therefore, according to the present embodiment, it is possible to use the reflection mirror 202 whose one side is 2 × 0.911 = 1.822 (mm) or more. As a result, one side of the reflection mirror 202 can be reduced by about 5% compared to the conventional case in which a beam waist is formed at the position of the irradiated surface S. When the thickness of the reflection mirror 202 is the same, by reducing one side of the reflection mirror 202 by about 5%, the vibration frequency of the reflection mirror 202 can be improved by about 15%.

As described above, according to the present invention, the spot SP is formed in the pixel area corresponding to the screen size and the resolution.
And the beam waist B so that the beam diameter is minimized at the position of the scanning unit 200.
The position of W can be optimized. By placing the spot SP in the pixel area, high-definition display according to the resolution is enabled. By minimizing the beam diameter at the position of the scanning unit 200,
The size of the reflection mirror 202 can be reduced. Since the reflecting mirror 202 can be made small, the reflecting mirror 202 can be vibrated at a high speed and with a large deflection angle.
Furthermore, the present invention can be realized only by adjusting the position of the beam waist BW as appropriate.
A new optical system is not required and a simple configuration can be achieved. Thereby, there exists an effect that a high resolution image can be displayed with a simple configuration.

The position of the beam waist BW can be appropriately set according to each parameter of the above formula (1). Further, the condensing optical system LN1 is not limited to the configuration in which the beam waist BW is formed in the optical path between the intermediate position M and the irradiated surface S. The condensing optical system LN1 includes a scanning unit 20
Any configuration may be used as long as the beam waist BW is formed at a position farther from the scanning unit 200 than an intermediate position M between 0 and the irradiated surface S. For example, the condensing optical system LN1 may form the beam waist BW on the extension of the optical path from the scanning unit 200 to the screen 110 and at a position farther from the irradiated surface S when viewed from the scanning unit 200. .

FIG. 8 illustrates a configuration for reducing the shift of each color light on the irradiated surface S. FIG. From the above equation (1), as the wavelength λ of the beam light is larger, the beam radius ω (
It can be seen that z) increases. Each peak wavelength of R light, G light, and B light is, for example, 650 n
m, 550 nm, and 450 nm. Since the peak wavelength of the R light is larger than the peak wavelength of the G light, when the distances from the R light source unit 101R and the G light source unit 101G to the irradiated surface S are substantially the same, the irradiated surface S The spot SP at R is larger for the R light than for the G light. Further, since the peak wavelength of the B light is smaller than the peak wavelength of the G light, when the distances from the B light source unit 101B and the G light source unit 101G to the irradiated surface S are substantially the same, The spot SP on the surface S is smaller for the B light than for the G light. For this reason, when the condensing optical system LN1 in which the distances from the light source portions for the respective color lights to the irradiated surface S are substantially the same and the beam waist is formed at the same position, color shift may occur in the screen 110.

For this reason, it is desirable for each condensing optical system LN1 to form a beam waist at a position corresponding to the peak wavelength. The condensing optical system LN1 provided for the R light forms a beam waist at a position closer to the irradiated surface S than the condensing optical system LN1 provided for the G light.
Thereby, the expansion of the beam diameter at the position of the irradiated surface S can be offset. The condensing optical system LN1 provided for the B light forms a beam waist at a position closer to the scanning unit 200 than the condensing optical system LN1 provided for the G light. Thereby, shrinkage of the beam diameter at the position of the irradiated surface S can be canceled out. Thus, by using the condensing optical system LN1 that forms the beam waist at the position corresponding to the peak wavelength, the size of the spot SP of each color light on the irradiated surface S can be made uniform. Thus, the screen 110
The color misregistration can be reduced, and a high-quality image can be displayed. In addition, the above formula (
According to 1), the larger the beam quality M ² , the larger the beam radius ω (z) at the distance z. Therefore, as the focusing optical system LN1 provided for the source beam quality M ² is larger, it may be configured to form a beam waist at a position closer to the scanning unit 200.

FIG. 9 illustrates the structure of the characteristic part of the image display apparatus according to the second embodiment of the present invention. The image display apparatus of the present embodiment has a first condensing optical system LN1 and a second condensing optical system LN2. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. Here, as in FIG. 6, the light path of G light among each color light will be described as a representative example. The first condensing optical system LN1 is provided between the G light source 101G and the reflection mirror 202. The first condensing optical system LN1 condenses the G light from the G light source unit 101G by the reflection mirror 202 of the scanning unit.

The second condensing optical system LN2 is provided between the reflection mirror 202 and the irradiated surface S. A beam diameter adjusting optical system 901 is provided between the reflecting mirror 202 and the second condensing optical system LN2. The beam diameter adjusting optical system 901 adjusts the beam diameter of the laser light. The beam diameter adjusting optical system 901 is not limited to being configured by a single lens, and may be configured by a plurality of lenses. The second condensing optical system LN2 includes the first condensing optical system LN1 and the reflection mirror 2.
02, G light sequentially passing through the beam diameter adjusting optical system 901 is condensed. In the configuration of the present embodiment, a beam waist BW is formed at a position between the intermediate position between the reflection mirror 202 and the irradiated surface S and the irradiated surface S by the second condensing optical system LN2.

Assume that the distance L ₀ from the reflection mirror 202 to the illuminated surface S is 1.5 m, and the distance L ₂ from the second condensing optical system LN2 to the illuminated surface S is 1.4 m. As in the first embodiment, the peak wavelength λ of G light is 550 nm and the beam quality M ^{2 is} 1.0. When the beam radius ω _P at the position of the irradiated surface S is 0.288 mm, the distance L ₁ between the irradiated surface S and the beam waist BW and the second condensing optical system LN2 are calculated using the above equation (1). The relationship with the beam radius ω _{L at} the position can be expressed as shown in FIG. From the relationship shown in FIG. 10, when the beam waist BW is formed at the position of the distance L ₁ = 144.314 mm from the irradiated surface S, the beam radius ω _{L at} the position of the second condensing optical system LN2 is minimized. I understand that. At this time, the beam radius ω _{L at} the position of the second condensing optical system LN2 is 0.850 mm.

The first condensing optical system LN1 and the beam diameter adjusting optical system 901 are configured to have a beam radius ω _L = 0.850 mm at the position of the second condensing optical system LN2. Further, in this embodiment, the reflecting mirror 2 is selected according to the configuration of the first condensing optical system LN1 and the beam diameter adjusting optical system 901.
The beam radius ω _S at the position 02 can be determined as appropriate. For example, the first condensing optical system LN1 is configured to form a beam waist at the position of the reflection mirror 202. For example, the first condensing optical system LN1 can set the beam radius ω _S at the position of the reflecting mirror 202 to 0.4 mm. Beam radius ω _{S at} the position of the reflecting mirror 202
By setting the length to 0.5 mm or less, it becomes possible to use the reflection mirror 202 having a side of 1 mm or less. The first condensing optical system LN1 is not limited to the configuration in which the beam waist is formed at the position of the reflecting mirror 202, but may be any configuration that can condense the laser light in the reflecting mirror 202. .

The beam diameter adjusting optical system 901 adjusts the beam diameter by expanding the laser beam condensed by the first condensing optical system LN1 to a predetermined beam radius ω _L at the position of the second condensing optical system LN2. .
In order to make the laser beam expanded to a predetermined beam diameter after passing through the first focusing optical system LN1 and not passing through the beam diameter adjusting optical system 901 enter the second focusing optical system LN2, a reflection mirror 2
The distance between 02 and the second condensing optical system LN2 is long. In order to capture the laser beam being scanned by the second condensing optical system LN2, the reflecting mirror 202 and the second condensing optical system LN2 are used.
The longer the distance between the two, the larger the second condensing optical system LN2 becomes necessary.

By adopting a configuration in which the beam diameter can be appropriately adjusted by the beam diameter adjusting optical system 901, it is not necessary to increase the distance between the reflecting mirror 202 and the second condensing optical system LN2. In addition, the second condensing optical system LN2 can be disposed at a position close to the reflecting mirror 202, whereby the effective diameter of the second condensing optical system LN2 can be reduced, and the small second condensing optical system LN2 is used. Can do. Thus, the degree of freedom of the configuration of the optical system can be increased by appropriately adjusting the beam diameter according to the configuration of the optical system. Note that the beam diameter adjusting optical system 901 may be omitted as long as laser light can be stored in the pixel region of the irradiated surface S and the reflection mirror 202. Also,
The function of the beam diameter adjusting optical system 901 may be provided to the second condensing optical system LN2.

By using the first condensing optical system LN1 and the second condensing optical system LN2 together, the reflection mirror 2 is used.
Compared to the case of using only the second condensing optical system LN2 provided between 02 and the irradiated surface S, the beam diameter at the position of the reflecting mirror 202 can be reduced. Thereby, the beam diameter at the position of the reflection mirror 202 can be further reduced, and the beam waist BW can be set at an optimum position.

FIG. 11 shows a schematic configuration of an image display apparatus 1100 according to the third embodiment of the present invention. The image display device 1100 is a so-called front projection type projector that supplies laser light to a screen 1110 provided on the viewer side and observes an image by observing light reflected by the screen 1110. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The laser beam from the scanning unit 200 passes through the emission window 1106 and then is displayed on the screen 1.
110 is incident. Also in the case of the present embodiment, similarly to the image display device 100 described above, the beam waist is formed in the optical path between the scanning unit 200 and the intermediate position of the irradiated surface S and the irradiated surface S by the condensing optical system LN1. Form. Thereby, an image with high resolution can be displayed with a simple configuration.

In the above embodiment, each color light source unit uses a semiconductor laser. However, the present invention is not limited to this as long as it can supply beam-shaped light. For example, each color light source unit may be configured to use a solid laser, a liquid laser, or a gas laser.

As described above, the image display device according to the present invention is suitable for displaying an image by scanning the light beam modulated according to the image signal.

1 is a diagram illustrating a schematic configuration of an image display apparatus according to Embodiment 1 of the present invention. The figure which shows schematic structure of a scanning part. The figure explaining the structure for driving a scanning part. The figure which shows the spot and pixel of a laser beam. 3A and 3B illustrate a configuration for forming a laser beam beam waist on an irradiated surface. 3A and 3B illustrate a structure of a characteristic part of an image display device. The figure which shows the relationship between the position of a beam waist, and a beam radius. The figure explaining the structure for reducing the shift | offset | difference of each color light in a to-be-irradiated surface. FIG. 6 is a diagram illustrating a configuration of a characteristic part of an image display device according to a second embodiment of the invention. The figure which shows the relationship between the position of a beam waist, and a beam radius. FIG. 9 is a diagram illustrating a schematic configuration of an image display device according to a third embodiment of the invention.

Explanation of symbols

100 image display device, 101R R light source unit, 101G G light source unit, 101B
B light source unit, 103 cross dichroic prism, 103a first dichroic film, 103b second dichroic film, 105 reflecting unit, 107 housing, 110 screen, 200 scanning unit, LN1 condensing optical system, S irradiated surface, 202 Reflection mirror, 2
04 outer frame portion, 206 first torsion spring, 207 second torsion spring, 301, 3
02 First electrode, 305 Mirror side electrode, 306 Second electrode, 307 Third torsion spring, 308 Fourth torsion spring, P pixel, SP spot, BW beam waist,
M intermediate position, 901 beam diameter adjusting optical system, LN1 first condensing optical system, LN2 second condensing optical system, 1100 image display device, 1106 exit window, 1110 screen

Claims (6)

An image display device that displays an image by scanning an irradiated surface with a beam light modulated in accordance with an image signal,
A light source unit for supplying the light beam;
A scanning unit that scans the light beam from the light source unit;
A condensing optical system for condensing the beam light,
2. The image display apparatus according to claim 1, wherein the condensing optical system forms a beam waist at a position farther from the scanning unit than an intermediate position between the scanning unit and the irradiated surface. The image display apparatus according to claim 1, wherein the condensing optical system forms the beam waist in an optical path between the intermediate position and the irradiated surface. A first condensing optical system that is provided between the light source unit and the scanning unit and condenses the beam light from the light source unit by the scanning unit;
A second condensing optical system provided between the scanning unit and the irradiated surface and forming the beam waist by condensing the beam light from the first condensing optical system. The image display device according to claim 1, wherein: A beam diameter adjusting optical system that is provided between the scanning unit and the second condensing optical system and adjusts a beam diameter of the beam light;
The image display apparatus according to claim 3, wherein the second condensing optical system condenses the beam light from the beam diameter adjusting optical system. 5. The scanning unit according to claim 1, wherein the scanning unit includes a reflection mirror that reflects the light beam, and causes the light beam to scan by resonating the reflection mirror. 6. Image display device. The light source unit supplies the light beams that are a plurality of color lights having different peak wavelengths,
The image display according to claim 1, wherein the condensing optical system is provided for each of the color lights and forms the beam waist at a position corresponding to the peak wavelength. apparatus.

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