JP2002131838A - Projecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a projecting distance without degradation of an optical performance such as aberration by distortion, etc., in a projecting lens system of a GLV projector. SOLUTION: A projecting apparatus 10 projects a light flux as an image on a screen 13 by scanning by a scanning mirror 14. The light flux includes a vertical or horizontal line of image components formed by a color combining mechanism 11 having a laser light source 16 and a spatial modulator 15 comprising a diffraction grating element, which modulates phase, arranged in a one- dimensional line. A projecting lens system 12 sequentially comprises a front group GF and a rear group GR in an order from an object to an image plane, and is arranged with an air gap between the front and rear groups. The scanning mirror 14 is arranged in the air gap between the front and rear groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection device,
In a projection apparatus using a laser light source and a GLV (Grating Light Valve) device, the present invention relates to a technique for shortening a projection distance without deteriorating distortion.

[0002]

2. Description of the Related Art In a projection apparatus, a so-called projector apparatus, a GL using a laser light source and a GLV (Grating Light Valve) device as a mechanism for creating a projection image.
There is a so-called V projector.

The GLV is a diffraction grating type spatial modulator having a ribbon structure which can be modulated using Coulomb attraction generated by application of a voltage. That is, as shown in principle in FIG. 17, the GLV 1 has, for example, three movable ribbons 1a, 1a, each of which constitutes one pixel (pixel) of the display screen.
When the GLV 1 is applied with a voltage, the movable ribbons 1a, 1a, 1a are lowered by an electrostatic force, and the six ribbons (reflecting portions) are composed of 1a and three fixed ribbons 1b, 1b, 1b. The ribbon changes from a simple reflecting mirror to a reflection type diffraction grating, and reflects the irradiated laser light and emits it as diffracted light.

The GLV 1 is, as described above, one pixel component composed of six ribbons, for example, 1080 pixels arranged in a vertical direction in a line on a silicon chip.

[0005] The GLV projector converts the above GLV into R
The three GLVs are used in correspondence with each color, and an electric signal corresponding to one column of pixel information is simultaneously applied to each GLV, and the GLV is used.
The laser beam diffracted by the laser beam is synthesized and projected onto a screen by a projection lens system.
Further, after the projection lens system, there is provided a scan mirror which scans the screen to form an image of a predetermined size on the screen from a light flux corresponding to one column of pixel information. For example, when the aspect ratio of the screen is 9:16, the scan mirror scans the screen horizontally by 1920 pixels and collects image information of about 2 million pixels in total at a rate of 60 frames per minute. Project on top.

[0008] As schematically shown in FIG. 18, the GLV projector 2 having the above-described configuration has a GL
After the light emitted from V1 passes through the lens 3, only the primary light of ± is transmitted through the schlieren filter 4, and
A real image 5 is formed at the focal point of. The zero-order light is blocked by the schlieren filter 4. Then, the real image 5 passes through the projection lens 6 and is reflected by the scan mirror 7 to scan on the screen 8 to display an image.

A GLV having a configuration as described above
The projector 2 is basically a front projector having a long focal length. If the projector 2 is applied to a rear projector having a short focal length, which projects the GLV projector 2 from the rear side of the screen, distortion becomes larger than a practical limit. There were drawbacks such as that

Hereinafter, the reason will be specifically described with reference to FIGS. 19 and 20. That is, as shown in FIG.
GLV size with 1080 pixels (height = 2h)
Is, specifically, 2h = 27 mm. This is 9:16
If the projection is performed on a 50-inch diagonal screen having the aspect ratio, the screen height is about 623 mm, and the lateral magnification M of the projection lens system is 23 times.

Conventionally, a projection lens used in a GLV projector is a telecentric lens having a focal length f of about 100 mm. The light flux relayed from the GLV at the same magnification forms an image near the focal point on the front side (light source side) of the projection lens, and the principal ray that has emitted this image enters the projection lens in parallel with the optical axis. Since the light goes to the screen after intersecting at the focal point on the rear side (screen side) of the projection lens, the distance from the rear focal point to the screen can be obtained by the product of the focal length f and the lateral magnification M of the projection lens system. That is, Mf = 2300 mm.

The tangent of the principal ray having the maximum inclination angle θ is tan θ = h / f = 0.135.
Here, as shown in FIG. 20, since θ = 7.7 °, the chief ray is 9: 1 in the horizontal direction by the scan mirror.
When the image is shaken to the edge of the screen having the aspect ratio of 6, the scan angle ψ becomes 13.5 °. At this time, the distance Mf from the rotation center of the scan mirror to the screen is 2300 mm
Therefore, the image height is increased to Mf / cosψ = 2365 mm, and the image height is increased by 8.78 mm obtained by multiplying the difference 65 mm from Mf by tan θ = 0.135.

The fact that the image height is high at the edge of the screen is caused by the distortion Δy caused by scanning.
Therefore, about 2.8% of distortion occurs at an image height of 311.5 mm, but distortion of 3% or less is acceptable for use as a display.

However, if it is attempted to project on a screen of the same size as described above with a short projection distance, it is inevitable that FIG.
9 (that is, tan θ increases), and at the same time, the scan angle also increases due to the relationship of tanψ16 / 9 tan θ. Therefore, as shown in FIG. 21, distortion (%) Δy / y = (1 / cos２１). ^-1 ) It is clear that tan θ increases sharply.

Therefore, a projection lens system using a scan mirror as the last optical element cannot be applied to an apparatus having a short projection distance Mf, such as a rear projector, because distortion increases, and is relatively long. It can be applied only to a front projector having a projection distance.

[0014]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to reduce a projection distance in a projection lens system of a GLV projector without deteriorating optical performance such as distortion.

[0015]

In order to solve the above problems, the present invention provides a color synthesizing mechanism having a laser light source and a spatial modulator in which diffraction grating elements for modulating a phase are arranged one-dimensionally. A projection device that projects a light beam including an image component for one vertical or horizontal line as an image on a screen by scanning with a scan mirror, and is configured by a front group and a rear group in order from the object side to the image plane side. The projection lens system is arranged with an air gap between the front group and the rear group, and the scan mirror is arranged at the air gap between the front group and the rear group.

Therefore, it is possible to reduce the focal length without deteriorating the distortion at the edge of the screen.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the projection apparatus according to the present invention will be described below with reference to the accompanying drawings.

The projection apparatus according to the present invention has a short projection distance suitable for a rear projector and a laser beam in a projector projection lens system using a grating light valve (GLV) as a diffraction grating type spatial modulator. The present invention realizes a projection lens system in which chromatic aberration and distortion are satisfactorily corrected in the wavelength range of light from red to blue, which is required for a GLV using a light source.

First, the overall configuration of the projection apparatus 10 will be described.

The projection device 10 has a color synthesizing mechanism 11 and a projection lens system 12. As shown in FIGS. 1 and 2, these optical engines, in order from the light source (object) side to the projection plane (image plane: screen) 13 side, have a color synthesizing mechanism 11 and a front side having a positive refractive power as a whole. A projection lens system 12 including a group GF and a rear group GR or the like having a negative refractive power as a whole is arranged, and a color combining mechanism is provided in the air gap between the front group GF and the rear group GR of the projection lens system 12. 11
A scan mirror 14 for displaying an image on the screen 13 by reflecting a light beam containing image components for one vertical or horizontal line and scanning the screen 13 is provided. Hereinafter, only the case where the light flux constituted by the color combining mechanism 11 is a light flux for one vertical line will be described.

As shown in FIG. 1, the color synthesizing mechanism 11 is provided with three GLVs 15 and three laser light sources 16 each of which is a diffraction grating type spatial modulator corresponding to each color of RGB. The parallel laser light from each laser light source 16 is diffracted and reflected by the GLV 15 and then combined as one light flux, and a light flux including pixel information for one vertical column is emitted to the outside. Note that each of the above GLVs
Reference numeral 15 denotes a spatial modulator in which diffraction grating elements for modulating a phase are arranged one-dimensionally.

The light beam emitted from the color synthesizing mechanism 11 has its optical axis bent by a reflecting mirror 18 composed of a combination of three anti-slope surfaces having a concave surface, a convex surface, and a flat anti-slope surface, and a schlieren filter 17. Only the ± primary light is transmitted and enters the projection lens system 12.

The light beam incident on the projection lens system 12 passes through the front group GF, and then reaches the scan mirror 14 disposed between the front group GF and the rear group GR. The luminous flux reflected by the scan mirror 14 and having its optical path changed at an angle corresponding to the width of the screen (projection surface) 13 further passes through the rear group GR.
One column of pixel information is scanned in the horizontal direction by 1920 pixels on the screen 13, and the image information of about 2 million pixels in total is easily transferred onto the screen (image plane) 13 at a speed of 60 frames in one minute. Reproduce.

Next, the projection lens system 12 will be specifically described.

FIGS. 4 and 5 are general views and three-dimensional conceptual views schematically showing constituent elements of the projection apparatus 10. FIG.

As described above, the projection lens system 12 has a front group GF having a positive refractive power as a whole and a rear group GR having a negative refractive power as a whole, and a lens group having a positive refractive power and a negative lens group. And a lens group having a refracting power of 1. An optical arrangement generally referred to as a retrofocus lens, in which nine groups and eleven elements are arranged with an air space therebetween.

As shown in the three-dimensional conceptual diagram of FIG. 5, the front group GF uses only a portion on one diameter due to the structural characteristics of the color synthesizing mechanism 11, so that it is relatively easy to simplify.
Since the rear group GR after the scan mirror 14 is used on the surface, it tends to be relatively complicated.

In the projection apparatus 10 using the GLV 15 as the color synthesizing mechanism 11, the specifications to be satisfied by the projection lens system 12 are as follows. That is, since 1/2 of the height (the size of the real image) of the GLV 15 is 13.5 mm, f =
The half angle of view at the time of 30 mm is tan ⁻¹ (h / f) = 24 °. On the other hand, the FNO of the projection lens system as viewed from the GLV 15 side (object side) needs to be 2.5 or more from the viewpoint of eliminating the interference noise speckle peculiar to the laser light source. Therefore, the lens type that satisfies the specification that the FNO as viewed from the object side is 2.5 or more and the half angle of view is 24 ° has an empirical rule of either a retrofocus configuration or a double Gaussian configuration. Adopts a retrofocus configuration.

Next, a first numerical example 12A of the projection lens system 12 will be described in detail.

In the following description and each table, "r
i "is the i-th surface counted from the object side and its radius of curvature,
“Di” indicates the surface distance between the i-th surface and the (i + 1) -th surface counted from the object side on the optical axis, “ni” indicates the refractive index of the i-th lens, and “νi” indicates the Abbe number of the i-th lens. And “RIMG” is a screen (image plane) 1
The radius of curvature of 8, "dOBJ" is the surface distance between the object and the surface r1, and "dIMG" is the surface distance between the surface r22 and the image surface.

As shown in FIG. 6, the front group GF includes, in order from the color combining mechanism 11 side (object side), a cemented lens of a first lens L1 and a second lens L2 having a positive refractive power as a whole. A first subgroup G1, a second subgroup G2 of a third meniscus lens L3 having a negative refractive power, and a cemented lens of a fourth lens L4 and a fifth lens L5 having a positive refractive power as a whole. The third lens group G3 includes a third lens group G3 and a fourth lens group G4 of a sixth lens L6 that is a convex lens having a positive refractive power.

The rear group GR includes a fifth subgroup G5 of a seventh lens L7 having a negative refractive power and an eighth lens group having a positive refractive power.
The sixth subgroup G6 of the lens L8, the seventh subgroup G7 of the ninth lens L9 having a negative refractive power, the eighth subgroup G8 of the tenth lens L10 having a negative refractive power, the 11
The ninth subgroup G9 of the lens L11 is formed.

The projection lens system 12 has an object distance of 15 mm, an object-side numerical aperture of 0.2, an object height (h / 2) of 13.5 mm,
Magnification (M) is 23x, projection distance is 570mm, image height is 311mm
It is.

Table 1 below shows various numerical values of the lenses constituting the projection lens system 12.

[0035]

[Table 1]

In Table 1, a surface r11 denoted by "STO" is a stop surface, and a scan mirror 14 is disposed on a dummy surface r12 denoted by "D", and a maximum of 33.5 luminous fluxes in the horizontal direction. Is to be shaken. Also,
The surfaces r13 and r22 to which "ASP" is added are constituted by axisymmetric general aspheric surfaces.

When the projection lens system 12 includes at least one aspherical surface, it is possible to effectively correct curvature of field and chromatic aberration.

In the aspherical shape, "z" is the coordinate of the aspherical surface in the optical axis direction, "c" is the curvature, "y" is the distance from the optical axis,
When “K” is a conical constant, z = cy ² / [1+ {1− (1 + K) c ² y ² } ^1/2 ] + A
and those represented by ^{y 4 + By 6 + Cy 8} + Cy 10. Here, A, B, C, and D are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively.

Table 2 below shows the fourth, sixth, eighth and tenth order aspherical coefficients of the surfaces r13 and r22.

[0040]

[Table 2]

It should be noted that "E" in Table 2 means an exponential expression with a base of 10 (the same applies to Table 5 described later).

The first to ninth small groups G1 to G9
The focal lengths f1 to f9 and the focal lengths fa and fb of the front group GF and the rear group GR are as shown in Table 3 below.

[0043]

[Table 3]

As shown in Table 3, the power (refractive power) of the front group GF is 1.08 times (absolute value) the power of the rear group. Further, since the Petzval sum of the front group GF and the rear group GR has substantially the same absolute value, the Petzval sum of the entire lens system can be kept equal, so that the field curvature can be reduced.

FIGS. 7 and 8 show the spherical aberration, astigmatism, distortion and lateral aberration of the first numerical embodiment 12A of the projection lens system 12. FIG. In each aberration diagram, the solid line is the wavelength 642.0n
m, the dashed line indicates the value at a wavelength of 532.0 nm and the dashed line indicates the value at a wavelength of 460.0 nm, respectively, and in the astigmatism diagram,
The thin line indicates the value of each wavelength on the sagittal image plane, and the thick line indicates the value of each wavelength on the meridional image plane.
The graph on the left shows the values of the wavelengths on the meridional image plane, and the graph on the left shows the values of the respective wavelengths on the sagittal image plane (the same applies to FIGS. 10, 11, 14, and 15 described later). Each of the values in the above aberration diagrams is a performance in a section including the optical axis (the scan angle of the scan mirror 14 is equivalent to 0 °).

As shown in the distortion diagram of FIG. 7, the distortion is about 1%. The amount of deviation between the wavelengths is 0.08%
It is as follows. This corresponds to 0.5 pixel.

By the way, as described above, specifically,
The focal length f of the projection lens system 12 is 30 mm. G
The size of the real image of the LV 15 is 27 mm, and when this is projected onto the screen 13 having a diagonal length of 50 inches and an aspect ratio of 9:16, the projection magnification M is 23 times. This projection magnification M
Since the approximate projection distance Mf is 690 mm from the relationship between the projection distance and the focal length f, as shown in FIG.
Is applied to the rear projector 20 in which the plane mirror 19 for turning the optical path is disposed within the projection distance Mf, the depth as the rear projector is expected to be about 350 mm, which is about half of the projection distance Mf.

Actually, the actual projection distance Mf of the projection device 10 is about 570 mm measured from the surface r1 of the first lens L1 on the optical axis. Therefore, it was confirmed that the rear projector 20 having a depth of about 360 mm can be realized by arranging the plane mirror 19 for turning back one optical path within the projection distance Mf.

As shown in the aberration diagrams of FIG. 7, the chromatic aberrations of the front group GF and the rear group GR have opposite signs, and
The absolute values are also corrected so that they become smaller individually.
It is clear that chromatic aberration is well corrected in the wavelength range from blue to red, which is required for the projection apparatus 10 using laser light as a light source.

The projection lens system 12A has a focal length f of 30 mm as described above, and
Focal length fa = 51.22 mm, focal length f of rear group GR
Since b = −55.43 mm, when the front group GF and the rear group GR are treated as thin lenses, the lens distance d between the front group GF and the rear group GR is 1 / f = 1 / fa + 1 / From the relationship of fb-d / fa / fb, d is calculated as 90.43 mm. Further, assuming that the distance from the object to the image plane when the magnification M is 23 is T, 0 = d ² −dT + T (fa + fb) + (M−1) ² faf
Since b / M, the above T is 837.7 mm. Further, the object distance S is given by: S = {(M−1) d + T} / ｛(M−1) −Md / f
a｝ = − 80.2 mm. From the above result, the image plane distance S 'is calculated as S' = T + S-d = 667 mm.

Therefore, when the pupil diameter is calculated with NA = 0.2, the radius is 10.2 mm. The scan mirror 14 must accept this, but as its inertia ratio increases, the amount of heat generated tends to increase.

In the second numerical embodiment 12B of the projection lens system 12 described below, in order to reduce the pupil diameter in view of the fact that as the pupil diameter increases, the calorific value of the scan mirror 14 increases, as described above. 20mm focal length f
It was made.

As shown in FIG. 9, in the projection lens system 12B of the second numerical example, the front group GF is
In order from the first side (object side), a first small group G1 composed of a cemented lens of a first lens L1 and a second lens L2 having a positive refractive power as a whole, and a third lens L having a negative refractive power
3rd second subgroup G2, 4th having a positive refractive power as a whole
The third subgroup G3, which is a cemented lens of the lens L4 and the fifth lens L5, and the fourth subgroup G6, which has a positive refractive power,
And a small group G4.

The rear group GR includes a fifth subgroup G5 of the seventh lens L7 having a negative refractive power and an eighth zoom lens having a positive refractive power.
The sixth subgroup G6 of the lens L8, the seventh subgroup G7 of the ninth lens L9 having a negative refractive power, the eighth subgroup G8 of the tenth lens L10 having a negative refractive power, the 11
The ninth subgroup G9 of the lens L11 is formed.

Projection lens system 1 in the second numerical example
2B has an object distance of 10 mm, an object-side numerical aperture of 0.2, an object height (h / 2) of 13.5 mm, a magnification (M) of 23 times, a projection distance of 570 mm, and an image height of 311 mm.

Table 4 below shows various numerical values of the lenses constituting the projection lens system 12.

[0057]

[Table 4]

In Table 4, the surface r11 denoted by "STO" is a stop surface, and the scan mirror 14 is disposed on the dummy surface r12 denoted by "D", and a maximum of 33.5 light beams in the horizontal direction. Is to be shaken. Also,
The surfaces r13 and r22 to which "ASP" is added are constituted by axisymmetric general aspheric surfaces.

Table 5 below shows the fourth, sixth, eighth and tenth order aspherical coefficients of the surfaces r13 and r22.

[0060]

[Table 5]

Further, the first to ninth subgroups G1 to G constituting the projection lens system 12B in the second numerical embodiment.
9 and the front group GF and the rear group GR
Are as shown in Table 6 below.

[0062]

[Table 6]

As shown in Table 6 above, the power of the front group GF is about 1.1 times (absolute value) the power of the rear group. Therefore, as in the case of the first numerical example 12A of the projection lens system 12, since the Petzval sum of the front group GF and the rear group GR has substantially the same absolute value, the Petzval sum of the entire lens system should be kept equal. Therefore, it is possible to reduce the field curvature.

FIGS. 10 and 11 show the spherical aberration, astigmatism, distortion and lateral aberration of the second numerical embodiment 12 B of the projection lens system 12. Each of the values in the above aberration diagrams is a performance in a section including the optical axis (the scan angle of the scan mirror 14 is equivalent to 0 °).

As shown in the distortion diagram of FIG. 10, the distortion is about 2.5%. In addition, the amount of deviation between the wavelengths is 0.1.
08% or less. This corresponds to 0.5 pixel.

The projection lens system 1 according to the second embodiment
2, the actual projection distance M of the projection device 10
f is about 5 measured on the optical axis from the surface r1 of the first lens L1.
It was 70 mm. Therefore, with the projection device 10 using one reflection mirror 18 within the projection distance Mf, a rear projector having a depth of about 360 mm can be realized.

As shown in the aberration diagrams of FIG.
The chromatic aberrations of the front group GF and the rear group GR are corrected so that the signs are opposite and their absolute values are individually reduced, and the chromatic aberrations of the front group GF and the rear group GR are reduced from the blue required for the projection apparatus 10 using laser light as a light source. It is clear that chromatic aberration is well corrected in the wavelength range up to red.

As described above, in the projection lens system 12, the focal length f of the entire system is 20 mm, the focal length fa of the front group GF = 33.12 mm, and the focal length fb of the rear group GR.
= −36.53 mm, when the front group GF and the rear group GR are treated as thin lenses, the lens interval d between the front group GF and the rear group GR is 1 / f = 1 / fa + 1 / fb. From the relationship of -d / fa / fb, d = 57.08 mm is calculated. Further, assuming that the distance from the object to the image plane when the magnification M is 23 is T, 0 = d ² −dT + T (fa + fb) + (M−1) ² faf
Since b / M, the above T is 554.7 mm. Further, the object distance S is given by: S = {(M−1) d + T} / ｛(M−1) −Md / f
a｝ = − 52.12 mm. From the above results, the image plane distance S 'is calculated as S' = T + S-d = 445.5.

Therefore, when the pupil diameter is calculated with NA = 0.2, the radius is 6.6 mm. First Numerical Example 1
Because the pupil diameter at 2A was 10.2 mm,
It was confirmed that it was reduced to 0%. This roughly corresponds to the ratio of the focal length of the entire system.

By the way, the projection lens unit 12B in the numerical example 2 is a final lens (eleventh lens) L11
Is a thick aspherical lens, and the first
It is in close contact with the zero lens L10 to form a cemented achromatic lens. It is conceivable to replace the cemented lenses L10 and L11 with an aspherical mirror.

In the following third numerical example 12C of the projection lens system 12, as shown in FIG. 12, the last surface of the projection lens system is an aspherical mirror. In the third numerical example 12C, the aspherical mirror is disposed perpendicular to the optical axis. However, the aspherical mirror may be inclined with respect to the optical axis to also have a function as a folding mirror that bends the optical axis. It is possible.

As shown in FIG. 13, in the projection lens system 12C according to the third numerical example, the front group GF has a positive refractive power as a whole in order from the color combining mechanism 11 side (object side). A first small group G1 composed of a cemented lens of one lens L1 and a second lens L2, a second small group G2 of a third lens L3 having a positive refractive power, a fourth lens L4 having a positive refractive power as a whole, The third lens group G3 includes a cemented lens with the fifth lens L5, and the fourth lens group G4 includes a sixth lens L6, which is a convex lens having a positive refractive power.

The rear group GR includes a fifth small group G5 of the seventh lens L7 having a negative refractive power and an eighth lens group having a positive refractive power.
A sixth subgroup G6 of the lens L8, a seventh subgroup G7 of the ninth lens L9 having a negative refractive power, and an eighth subgroup G8 of an aspherical mirror REFL having a negative refractive power.

Projection lens system 1 in the second numerical example
In 2C, the object distance is 10 mm, the object-side numerical aperture is 0.2, the object height (h / 2) is 13.5 mm, the magnification (M) is 23 times, the projection distance is 460 mm, and the image height is 311 mm.

Table 7 below shows various numerical values of the lenses constituting the projection lens system 12C.

[0076]

[Table 7]

In Table 7 above, the surface r11 denoted by “STO” is a stop surface, and the scan mirror 14 is disposed on the dummy surface r12 denoted by “D”, and a maximum of 33.5 light beams in the horizontal direction. Is to be shaken. Also,
The surfaces r13 and r19 to which "ASP" is added are constituted by axially symmetric general aspheric surfaces.

Table 8 below shows the fourth, sixth, eighth and tenth order aspherical coefficients of the surfaces r13 and r19.

[0079]

[Table 8]

Further, the first to eighth subgroups G1 to G constituting the projection lens system 12C in the third numerical example are described.
8 and the front group GF and the rear group GR
Are as shown in Table 9 below.

[0081]

[Table 9]

As shown in Table 9, the power of the front group GF is about 25.8 times (absolute value) the power of the rear group, and the power is concentrated on the front group GF.

FIGS. 14 and 15 show the spherical aberration, astigmatism, distortion, and lateral aberration of the third numerical embodiment 12C of the projection lens system 12. FIG. Each of the values in the above aberration diagrams is a performance in a section including the optical axis (the scan angle of the scan mirror 14 is equivalent to 0 °).

As shown in the distortion diagram of FIG. 10, the distortion is -2%. The amount of deviation between the wavelengths is 0.08
% Or less. This corresponds to 0.5 pixel.

In the first to third numerical embodiments 12A, 12B, and 12C of the projection lens system 12, the scan mirror 14 has a horizontal half angle of view of 17.5 ° and 3 °.
Projection lens system 1 when light beam is swung by 3.5 °
2, the optical performance of FIG. 7, FIG. 8, FIG. 10, FIG.
And the performance (scan angle 0 °) in the section including the optical axis shown in each aberration diagram shown in FIG.

FIG. 16 shows a projection apparatus 10 according to the present invention.
It shows the position (wavelength: green) of the principal ray on the screen (image plane) 13. That is, FIG. 16 shows an aspect ratio of 9:
Although the upper half of the 16 screens 13 is shown, about 3% of distortion is observed in the diagonal position in the y direction and about 5% in the x direction. Since the scan angle of the scan mirror 13 at this time is 33.5 °, tan
33.5 ° = 0.66. Therefore, if this is the case of the front projector described in the section of the related art, the distortion in the y direction will be 30% or more, as shown in FIG.

The projection device 10 according to the present invention includes a laser light source 16.
And a scanning mirror 14 for converting a light flux including image components for one vertical or horizontal row, which is constituted by a color synthesizing mechanism 11 having a spatial modulator (GLV) 15 in which diffraction grating elements for modulating a phase are arranged one-dimensionally. Are projected as an image on the screen 13 by the scanning according to the order, from the object side to the image plane side, a front group GF having a positive refractive power as a whole, and a rear group GR having a negative refractive power as a whole. Are arranged with an air gap between them, the scan mirror 14 is arranged at an air gap between the front group GF and the rear group GR, and within the air gap between the rear group GR and the screen 13. At least one reflection mirror 18 for bending the optical path is arranged. Accordingly, the focal length can be reduced without deteriorating the distortion at the edge of the screen.
It can be applied to a rear projector.

The specific shapes and structures of the respective parts shown in the above-described embodiments are merely examples for embodying the present invention. The scope should not be construed as limiting.

[0089]

As described above, the present invention relates to a vertical or horizontal image component constituted by a color combining mechanism having a spatial light modulator having a laser light source and a number of spatial modulators arranged in a line. A projection lens system configured by a front lens group and a rear lens group in order from the object side to the image plane side. Since the scan mirror is arranged at the air interval between the front group and the rear group while disposing the air interval between the group, the distortion that increases when the focus is shortened by the rear group is corrected. Thus, the projection device can be applied to a rear projector having a short projection distance.

According to the second aspect of the present invention, the front group has a positive refractive power as a whole, and the rear group has a negative refractive power as a whole. Can be shortened without deteriorating the focal length.

According to the third aspect of the present invention, since at least one reflecting mirror for bending the optical path is arranged in the air gap between the rear group and the screen, the projection distance can be reduced to approximately half. Thus, a rear projector with a short depth can be realized.

In the fourth and seventh aspects of the present invention, since each surface constituting the rear group includes at least one aspherical surface, field curvature and chromatic aberration can be effectively reduced. Can be corrected.

According to the fifth aspect of the present invention, since the refractive power of the front group is set to about 1.1 times the refractive power of the rear group in absolute value, the Petzval sum of the projection lens system is kept small. And the field curvature can be further reduced.

According to the sixth aspect of the present invention, both the front group and the rear group have a positive refractive power as a whole, and the most image-side surface of the rear group is an aspherical reflecting surface. Therefore, the distortion that increases when the focus is shortened by the rear lens group is corrected, and the projection apparatus can be applied to a rear projector having a short projection distance.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the projection apparatus of the present invention together with FIG. 2 and FIG. 16, and FIG. 1 is a horizontal sectional view schematically showing the projection apparatus.

FIG. 2 is a longitudinal sectional view of the projection device.

FIG. 3 is a longitudinal sectional view schematically showing an example in which the projection apparatus of the present invention is applied to a rear projector.

FIG. 4 is a sectional view schematically showing a projection lens system.

FIG. 5 is an overall three-dimensional conceptual diagram.

6 shows Numerical Example 1 of the projection lens system together with FIGS. 7 and 8, and FIG. 6 is an enlarged sectional view showing a lens configuration.

FIG. 7 is a diagram illustrating spherical aberration, astigmatism, and distortion.

FIG. 8 is a diagram showing lateral aberration.

FIG. 9 shows Numerical Example 2 of the projection lens system together with FIGS. 10 and 11, and FIG. 9 is an enlarged sectional view showing a lens configuration.

FIG. 10 is a diagram showing spherical aberration, astigmatism, and distortion.

FIG. 11 is a diagram illustrating lateral aberration.

12 shows Numerical Example 2 of the projection lens system together with FIG. 13 to FIG. 15, and FIG. 12 is an enlarged sectional view of the whole.

FIG. 13 is an enlarged sectional view showing a lens configuration.

FIG. 14 is a diagram showing spherical aberration, astigmatism, and distortion.

FIG. 15 is a diagram showing lateral aberration.

FIG. 16 is a diagram showing a position of a chief ray on an image plane.

FIG. 17 is a diagram schematically showing the operation principle of the GLV.

18 shows a projection apparatus using a conventional GLV together with FIGS. 19 to 21. FIG. 18 is a view schematically showing a basic configuration.

FIG. 19 is a schematic diagram showing the principle of projection of an image on a screen.

FIG. 20 is a diagram schematically showing how distortion occurs at both ends of the screen.

FIG. 21 is a graph showing a relationship between a tilt angle of a principal ray and a degree of occurrence of distortion.

[Explanation of symbols]

10 Projection device, 11 Color synthesis mechanism, 12 Projection lens system, 15 Spatial modulator, 16 Laser light source, GF Front group, GR Rear group, REFL Reflection surface composed of aspherical surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03B 21/14 G03B 21/14 Z 21/28 21/28 H04N 3/10 H04N 3/10 5/74 5 / 74 H 9/31 9/31 ACF term (reference) 2H041 AA16 AB12 AC06 AZ01 AZ05 AZ08 2H045 BA24 BA32 CA34 DA01 DA31 2H087 KA06 LA03 PA06 PA08 PA09 PA19 PA20 PB09 PB11 QA02 QA07 QA13 QA22 QA26 RA43 A RA45 RA46 TA04 TA05 TA06 TA08 5C058 BA23 BA27 EA02 EA05 EA12 EA13 EA27 EA42 5C060 BA03 BA08 BB11 BC05 BD02 BE05 BE09 EA01 GA02 GB02 GB06 HC01 HC20 HC21 HD00 JA01 JB06

Claims (7)

[Claims] 1. A light beam including image components for one vertical or horizontal line constituted by a color synthesizing mechanism including a laser light source and a spatial modulator in which diffraction grating elements for modulating a phase are arranged one-dimensionally. A projection device for projecting an image on a screen by scanning with a mirror, comprising: a projection lens system configured by a front group and a rear group in order from an object side to an image plane side; A projection mirror, wherein the scanning mirror is disposed at an air interval between the front group and the rear group. 2. The projection apparatus according to claim 1, wherein the front group has a positive refractive power as a whole, and the rear group has a negative refractive power as a whole. 3. The projection device according to claim 1, wherein at least one reflecting mirror for bending an optical path is arranged in an air space between the rear group and the screen. 4. The projection apparatus according to claim 1, wherein each surface constituting the rear group includes at least one aspheric surface. 5. The projection apparatus according to claim 1, wherein the refractive power of the front group is about 1.1 times the refractive power of the rear group in absolute value. 6. The front group and the rear group both have a positive refractive power as a whole, and the surface of the rear group closest to the image plane is a reflecting surface formed by an aspherical surface. The projection device according to claim 1. 7. The projection apparatus according to claim 5, wherein each surface constituting the rear group includes at least one aspheric surface.