JPH07270791A - Projector - Google Patents

Abstract

PURPOSE:To improve projection characteristics by providing a projector with a light valve means, an illumination optical system and an imaging means and disposing a luminous flux section deforming element in the optical path of this illumination optical system. CONSTITUTION:The light of a light source 101 is condensed onto one point on the optical axis of a reflection mirror 102 and is made incident on a condenser lens 103. This light is made incident on a prism 104 which is the luminous flux section deforming element. Its optical path is bent by this prism and is expanded in the luminous flux diameter in the curving direction. The luminous flux for illumination from the prism 104 is emitted perpendicularly from the exit surface and its sectional shape is so adjusted as to be inscribed with the four corner parts of the image information display surface of the light valve 105 in its irradiation region. The magnification rate of the prism 104 is determined by a vertex phi1 and incident angle theta1. The luminous flux reflected by the light valve 105 is spatially modulated according to the image information of the image information display surface and is projected by an imaging lens 106 to form image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection device applied to, for example, a video projector.

[0002]

2. Description of the Related Art In recent years, a so-called video projector has been known as a device for projecting an image on a relatively large screen. This video projector is composed of a phase modulation type configuration that combines the birefringence of liquid crystal and a polarization optical system, and combines a liquid crystal having a light scattering property such as polymer dispersion type liquid crystal and a Schlieren optical system. It is roughly divided into those having a scattering type structure.

In such a video projector, the illumination light flux from the light source is applied to the image information display surface of the light valve means, and the spatially modulated light flux is applied to the screen which is the projection surface. Generally, an image is projected, and the light valve means is illuminated with illumination light to the light valve means uniformly and with high illuminance (intensity), and the image when projected onto the screen is bright and uneven. It is required to be absent.

As a light source used in such a video projector, a white light source which emits a high-luminance illumination luminous flux such as a metal halide lamp or a xenon lamp is generally useful. A combination of these white light sources, a concave mirror such as an elliptical mirror, a parabolic mirror, and a spherical mirror, and a condenser lens is generally used as a light source means or an illumination optical system.

[0005]

The cross section of the illumination luminous flux emitted from the light source means as described above is generally circular, but the image information display surface of the light valve means irradiated with this illumination luminous flux. Is often rectangular. Therefore, in order to irradiate the entire surface of the image information display surface with the illumination light flux, it is necessary to cover at least the entire rectangular region of the image information display surface with the circular (cross-sectional) illumination light flux.

When such an illumination optical system is used, an area where the image information display surface is not illuminated, that is, a light flux which is not used without being guided to the light valve means is partially included in the illumination light flux irradiation area (light flux cross section). Exists. An example of this state will be described with reference to FIG.

In the irradiation state shown in FIG. 9, the image information display surface 95 and the irradiation area 98 are arranged so that the rectangular image information display surface 95 is included in the irradiation area 98 (circular area) of the illumination luminous flux.
Are set, and these are installed so that the corners of the image information display surface 95 are inscribed in the irradiation area 98 for the most efficient irradiation. The irradiation area 98 here means a range in which a sufficient irradiation intensity is obtained by the illumination light, that is, a so-called effective illumination area.

As is clear from this figure, the irradiation area 98
Of these, the shaded portion y is a region where the image information display surface 95 is not illuminated, and is generally a light beam that is shielded here and is not used for the illumination system and the imaging system. Therefore, the light amount loss of the illumination luminous flux is caused by the region y where the image information display surface 95 is not illuminated.
The amount of light emitted from the illumination light flux irradiating the laser light is generated.

Here, in the conventional illumination optical system and the projection apparatus using the same, there are increasing demands for improving the irradiation intensity of the light valve means and the projection intensity and brightness of the projected image. However, in order to meet these demands, only measures for increasing the power of the light source itself have hitherto been taken, and there have been problems that the device becomes large and the manufacturing cost rises. Further, no specific measures have been taken against the above-described light amount loss.

Further, the concentric circles within the irradiation area 98 of the illumination light flux are contour lines for explaining the light intensity distribution state, and a general illumination light flux reaches its maximum near the center (optical axis) and approaches the peripheral portion. It has a light amount distribution that weakens (a distribution close to a so-called Gaussian distribution). For this reason, the explanatory line showing the light intensity distribution state of the illumination light flux is concentric as shown in this figure.

Here, a white light source such as a metal halide lamp or a xenon lamp, which is useful for obtaining high-intensity illumination light, is not an ideal point light source but has a certain spread. For example, in a metal halide lamp,
The light emitting part has reached a length of several millimeters.

Conventionally, when illuminating the image information display surface with an illumination light flux from a light source using a white light source and a reflecting mirror (concave mirror), the light source position (light emitting portion) and the focal position of the reflecting mirror are made to coincide with each other. It is common to have

However, even if an ideal point light source and a reflecting mirror are combined, the shadow of the lamp appears on the image information display surface side, so that the central portion of the irradiated light beam may become dark or the intensity may be uneven. In addition, when a light source of a light emitting unit having a length and a reflecting mirror are combined, the irradiation light flux does not become an ideal parallel light flux. There will be more loss.

Therefore, in practice, the position of the light source is arranged so as to be slightly shifted in the optical axis direction with respect to the focal position of the reflecting mirror, and the illumination light flux emitted from the light source is focused and irradiated on the irradiation surface. The layout is as shown below. As a result, the shadow in the central part and the light amount loss in the illumination system are minimized, but the light intensity at each part in the light flux cross section of the illumination light flux on the irradiation surface is similar to the so-called Gaussian distribution. The light is concentrated (the light amount density is high) in the central portion of the (image information display surface).

Therefore, the illumination intensity becomes weaker as the distance from the center of the optical axis in the image information display surface increases. This state will be described with reference to FIG. This figure shows a state in which an illumination light flux having a Gaussian distribution in illumination intensity is applied to a rectangular image information display surface, and the concentric circles on the image information display surface show the light intensity (light quantity density) in the same manner as described above. It is a contour-like explanation line shown, which is higher toward the center.

In this diagram, the light intensity when the light intensity on the image information display surface is divided by a plane parallel to the longitudinal direction of the image information display surface and perpendicular to the paper surface. A diagram showing the distribution is shown in FIG. 10A so as to correspond to the long side of the image information display surface. Further, a diagram showing a light intensity distribution when the center of the image information display surface is divided by a plane parallel to the lateral direction of the image information display surface and perpendicular to the paper surface is a short side of the image information display surface. 10 (b) so as to correspond to.

The vertical axis (the upper horizontal axis in FIG. 10B) of FIGS. 10A and 10B represents the light intensity, and the horizontal axis is the length of the long side or the length of the short side of the image information display surface. (Position within a rectangular area) is shown. In addition, in any diagram, the point t1
Is the position where the image information display surface intersects the optical axis (the center of the irradiation area, the center of the image information display surface).

As is clear from FIG. 10, in the image information display surface, the light intensity becomes weaker as the distance from the point t1 at the center position increases. In particular, it can be seen that the light intensity is drastically reduced (or the light quantity density is low or the irradiation light quantity is low) at a position closer to the end on the longer side than the point t1.

As described above, in the conventional illumination system, in order to suppress the light amount loss, the brightness of the illumination luminous flux irradiated to the image information display surface becomes uneven (the difference in the illumination intensity between the peripheral portion and the central portion is large. Therefore, there is a problem that uneven brightness occurs in the image projected on the screen.

In order to eliminate the uneven brightness, the irradiation area of the illumination light beam is expanded so as to have a considerably large light beam cross section with respect to the rectangular image information display surface, and the difference in intensity between the central portion and the peripheral portion is reduced. However, since the area that does not illuminate the image information display surface is enlarged, the utilization efficiency of the illumination light flux emitted from the light source is significantly reduced, and the image projected on the screen is darkened as a result. It was

The present invention has been made in view of these problems, and its main object is to provide a projection apparatus having excellent projection characteristics. It is another object of the present invention to provide a projection device that can improve the utilization efficiency of the light flux from the light source, thereby constructing an illumination system with less loss of light quantity and obtaining a bright image.

Further, by constructing an illumination optical system capable of obtaining an illumination light having a uniform intensity as much as possible by suppressing the intensity difference between the central portion and the peripheral portion on the light valve means due to the illumination light, the intensity is utilized. It is an object of the present invention to provide a projection device in which unevenness and brightness are less likely to occur.

[0023]

[Means for Solving the Problems] In order to achieve the above object,
In the invention according to claim 1, a light valve means for spatially modulating a light beam emitted for displaying a two-dimensional image, and an illumination optical system for irradiating an illumination light beam from the light source means on an image information display surface of the light valve means. And an image forming means for forming an image of the illumination light flux spatially modulated on the image information display surface of the light valve means on the projection surface, and transforming the light flux cross section of the illumination light flux in one predetermined direction. Provided is a projection device, wherein a beam cross-section deforming element is provided in an optical path of the illumination optical system.

The illumination optical system used in the present invention is as follows.
If the light intensity distribution state of the illumination light flux at each portion in the light flux cross section at the irradiation position has a so-called Gaussian distribution, the illumination light can be particularly efficiently irradiated to the light valve means. For this reason, the illumination optical system (using the projection device) having a configuration in which such a Gaussian distribution occurs
If so, the present invention can be applied, and its configuration is not particularly limited.

Next, in the invention described in claim 2 of the present application,
2. The projection device according to claim 1, wherein the illumination optical system includes a combination of a light source having a finite size light emitting portion and a concave mirror that reflects a light beam from the light source and guides the light flux toward the irradiation position direction. The light source means is provided.

As described above, this is generally used as the light source means of the illumination light that causes the Gaussian distribution at the irradiation position, and the manufacturing cost of the illumination optical system itself and the projection device can be suppressed. It is a useful light source means. Further, there is an advantage that it can be incorporated into a conventional device with a simple improvement.

Next, the invention described in claim 3 is the projection apparatus according to claim 1 or 2, wherein the luminous flux cross-section deforming element enlarges the luminous flux cross-section in the longitudinal direction of the image information display surface. It is characterized by being a thing. most,
The projection apparatus according to the present application can be constructed by using, as the luminous flux cross-section deforming element, one that reduces the luminous flux cross-section in the lateral direction of the image information display surface.

According to a fourth aspect of the present invention, in the projection apparatus according to the third aspect, when the luminous flux cross-section deforming element has a circular luminous flux cross-section of the illumination luminous flux incident on the luminous flux cross-section deforming element, When the luminous flux cross-sectional diameter of the illumination luminous flux is R, the magnification of the luminous flux cross-section deforming element is m, the short-side length of the image information display surface is a, and the long-side length is b, the following is obtained. We have proposed a projection device characterized by satisfying the conditions. R = √2 · am = b / a

As described above, when the cross section of the light flux is reduced in the lateral direction of the image information display surface, it is preferable to satisfy the following conditions. R = √2 · b m = a / b

Further, the invention according to claim 5 is the invention according to claim 1,
In the projection device described in item 2, 3 or 4, there is proposed a projection device in which the light flux cross-section deforming element is a prismatic optical element.

As the other optical element, an optical element to which a cylindrical lens or the like is applied can be considered. Whichever optical element is used, it is preferable that the achromatic condition is satisfied according to the illumination luminous flux of the illumination means used. This is to prevent the occurrence of chromatic aberration and the like due to the deformation of the cross section of the light beam.

[0032]

Since the present invention is constructed as described above,
The following effects are achieved. First, in the invention described in claim 1, the light valve means for spatially modulating the luminous flux irradiated for the two-dimensional image display, and the illumination luminous flux from the light source means are irradiated to the image information display surface of the light valve means. The image information display surface of the light valve means includes the illumination optical system and the image forming means for forming an image of the illumination light flux spatially modulated on the image information display surface of the light valve means on the projection surface. The illumination light flux is spatially modulated on the basis of the image information shown in, and an image is projected on the projection surface.

Here, the light valve means of the present invention displays the image information according to a predetermined input signal when the illumination light flux emitted from the light source means with a predetermined intensity is applied to the image information display surface. The image is partially spatially modulated on the surface and reflected (or transmitted), and a projected image is obtained by the spatially modulated reflected (or transmitted) light.

As this light valve means, for example,
A combination of the image information display surface configured to deform the surface of an oil film or a metal film by electronic means and a Schlieren optical system, or a combination of the image information display surface made of an electro-optical crystal such as liquid crystal and a polarizing plate. The ones that are known are known.

The light valve means of the present invention can be applied by any of these methods, and can be applied to both so-called reflective type and transmissive type. That is, the method is not particularly limited as long as the illumination light flux is spatially modulated and projected.

Next, the illumination optical system of the present invention is an optical system for guiding the luminous flux emitted from the light source means to the entire image information display surface of the light valve means, and in the present invention, the luminous flux cross section in the optical path. Is provided with a light beam cross-section deforming element that deforms in one direction.

The specific structure of such an illumination optical system is as follows.
It is a timely selection according to the design of the device itself. For example, if the light valve means is a combination of an electro-optical crystal such as liquid crystal and a polarizing plate, the light flux from the light source can have a specific uniform vibration surface. Since it is necessary to polarize and irradiate the linearly polarized light having the above, the above-mentioned illumination optical system may be provided with a polarization adjusting member or the like in its optical path. Such a polarization adjusting member may have at least a function of converting the light flux from the light source into a light flux having a uniform polarization plane.

Further, for example, if the light valve means has a structure in which the surface of the oil film or the metal film is deformed by electronic means, it is not necessary to convert it into linearly polarized light, and the illumination optical system can convert the light flux from the light source as much as possible. It is sufficient to use a structure that efficiently irradiates with uniform intensity.

Next, the image forming means of the present invention is not particularly limited as long as it has a structure for forming an image of the light beam spatially modulated by the light valve means on a projection surface such as a screen. Not a thing. In this case, it goes without saying that if the light valve means is of a reflective type, it is formed on the optical path of reflected light, and if it is of a transmissive type, it is formed in consideration of transmitted light. Further, it is preferable to include a unit for changing the image forming state according to the difference in the distance to the projection surface, for example, an image forming adjusting unit for focusing.

Next, in the present invention, since the light beam cross-section deforming element for deforming the light beam cross section of the illumination light beam in one predetermined direction is provided in the optical path of the illumination optical system, the light source means of the illumination optical system is provided. When the illumination light flux from is guided to the image information display surface of the light valve means, the light flux cross section is deformed in one predetermined direction.

For example, since the cross section of a light beam from a general light source means is a circular cross section, when it is deformed in one specific direction, it becomes an elliptical light beam cross section. Further, at this time, when the illumination light flux has the Gaussian distribution as described above, the contour lines showing the intensity distribution are similarly transformed from circular to elliptical. Then, the luminous flux thus transformed illuminates the image information display surface of the light valve means as an illuminating luminous flux.

The structure of the light beam cross-section deforming element is not particularly limited as long as it deforms the light beam cross-section in a predetermined direction in the optical path of the illumination optical system.
For example, it may be constituted by a light transmissive member such as a prism or a cylindrical lens, a light reflective member such as a reflecting mirror (cylindrical mirror) having a cylindrical reflecting surface, or the like.

When a prism or a reflecting mirror is used, the optical path can be bent at the same time, and when a cylindrical lens or the like is used, the optical path can be formed linearly. Moreover, it is preferable that these optical elements satisfy the achromatic condition for the luminous flux of the illumination light. This is to prevent inconvenience of the image due to chromatic aberration and the like. The achromatic prism also has an advantage that an optical path can be formed such that after the optical path is bent, the light path is further converted into parallel (to the original optical path) and emitted.

By the way, the image information display surface of the light valve means is generally rectangular, and the cross section of the illumination luminous flux is generally circular. In the present invention, when the illumination light flux is radiated to the image information display surface by the light flux cross-section deforming element, it is converted into a light flux having an elliptical cross section. There is a region within the region where the image information display surface is not illuminated.

This state will be described with reference to FIG. FIG. 7 shows a state in which the light flux of a light source having a circular cross section is transformed into an elliptical cross section and is applied to the image information display surface of the rectangular light valve means. In this figure, the irradiation area 78 of the illumination luminous flux is shown.
Is an elliptical shape after being deformed by the beam cross-section deforming element,
The irradiation is performed so as to cover the entire rectangular shape of the image information display surface 75.

At this time, in order to reduce the light amount loss as much as possible, the four corners of the image information display surface 75 are irradiated with the irradiation area 7.
It is preferable to determine the mutual size and irradiation position relationship so as to be inscribed in No. 8. The irradiation area 78 is a range where a sufficient irradiation intensity is obtained by the illumination light, that is, a so-called effective illumination area.

As is clear from this figure, the shaded area x is the area where the image information display surface 75 is not illuminated, and the light flux in this area is the unused light flux in the projection device. In other words, the luminous flux irradiating this area x becomes a light amount loss in this device.

Here, it can be seen that the area x is obviously smaller than the area y in FIG. 9 described above.
In particular, when viewed in a cross section in the single-handed direction, the region y includes almost half the region from the end position to the center position.
It is clear that in the region x, it is 1/4 or less.

Therefore, even if the illumination light flux is uniform in the light flux cross section, the area of the region x which influences the light intensity loss is small, so that the light intensity loss is remarkably large as compared with the conventional illumination light having a circular cross section. It will be few. As a result, the amount of light that was conventionally lost will be guided to the image information display surface.
The effective irradiation light amount increases, and the projected image also becomes brighter and the brightness increases as compared with the conventional image due to the bright illumination light.

In other words, since the amount of illumination light flux reaching the image information display surface of the light valve means increases, the amount of illumination light flux spatially modulated by the image information display surface also increases. Therefore, the projection image formed on the screen has a larger amount of light than that of the conventional art and becomes brighter than the conventional one as a whole.

The rectangular area of the image display surface of the general light valve means used in a video projector or the like has an aspect ratio of 3: 4 or 9:16, and the illumination luminous flux is adjusted in accordance with these rectangular areas. It suffices to determine the deformation ratio and the like of the light flux cross section.

As described above, in the present invention, by providing the light beam cross-section deforming element for deforming the cross-sectional shape of the illumination light beam in one predetermined direction in the optical path of the illumination optical system, the area of the region not illuminated by the light valve means Is small. This degree of deformation may be determined in a timely manner by changing it according to the shape of the cross section of the illumination light flux, which enables bright illumination (large irradiation light amount) and image projection with little light amount loss. .

The direction of deformation by this element is determined by the cross section of the light beam from the light source means and the shape of the light valve means. When the illumination light flux of circular cross section is guided to the rectangular irradiation area, the longitudinal direction of the rectangular area. The illumination light flux may be deformed so that it becomes an elliptical shape that becomes extremely long. Specifically, it is conceivable that the rectangular area is enlarged in its longitudinal direction, reduced in its lateral direction, or deformed by combining these enlargements and reductions.

By the way, in the illumination optical system used in the present invention, the light intensity distribution state of each portion of the illumination light beam at the irradiation position in the light beam cross section has a distribution close to a so-called Gaussian distribution (or Gaussian distribution). In particular, it is possible to irradiate the light valve means with illumination light particularly efficiently. Therefore, it is particularly effective to apply the present invention to an illumination optical system (a projection apparatus using the same) having a configuration in which a distribution (or a Gaussian distribution) close to such a Gaussian distribution is generated.

As described above, when the illumination light flux has a distribution close to a Gaussian distribution (or a Gaussian distribution), the intensity of the emitted light is different between the central position (near the optical axis) and the peripheral position of the light valve means. different. For example, in the case of an illumination light flux having a circular cross section as in the conventional case, the difference between the irradiation light amount at the peripheral portion in the longitudinal direction and the irradiation light amount at the central portion becomes large, and even in the projected image, there is a difference in brightness between the central portion and the peripheral portion. Since the difference becomes large, excellent projection characteristics cannot be obtained.

However, according to the present invention, even an illumination light flux having a distribution close to a Gaussian distribution (or a Gaussian distribution),
The intensity distribution state with the central portion (near the optical axis) as the apex is dispersed by deforming the cross section of the luminous flux, and as a result, the luminous flux intensity (light amount density) in the central portion is reduced, and the periphery of the light valve means is reduced. The luminous flux intensity in the vicinity of the area increases, and the difference in the intensity of the irradiation light between these irradiation positions becomes small.

This will be described with reference to FIGS. 6 and 7. First, as shown in FIG. 7, when the cross-sectional shape of the illumination light flux having a distribution close to a Gaussian distribution is deformed in one predetermined direction,
The contour lines 79 indicating the intensity distribution state are also deformed in the same manner as the irradiation region 78 is deformed. The state of the irradiation intensity on the light valve means in this state is shown in FIG.

FIG. 6 is a quadrangle when the luminous flux cross section of the illumination luminous flux having a distribution close to a Gaussian distribution is deformed in the longitudinal direction of the image information display surface (enlarged in the longitudinal direction or reduced in the lateral direction) and irradiated. It is a diagram which shows the light intensity distribution state which looked at the image information display surface 75 of a shape from right above. The concentric ellipse on the image information display surface 75 is a contour-like explanatory line showing the light intensity distribution state, and it is higher toward the center.

In this diagram, in order to show the light intensity distribution state on the image information display surface, a diagram showing the light intensity distribution when the center is divided by a plane parallel to the longitudinal direction and perpendicular to the paper surface is It is shown in FIG. 6C so as to correspond to the long side of the information display surface. Further, the diagram showing the light intensity distribution when the center is divided by a plane parallel to the lateral direction of the image information display surface and perpendicular to the paper surface is shown in FIG. 6 so as to correspond to the short side of the image information display surface. (D).

6 (c) and 6 (d), the vertical axis (the upper horizontal axis in (d)) represents the light intensity, and the horizontal axis (the left downward axis in (d)). Indicates the position in the long side direction (the position in the cross section) or the position in the short side direction (the position in the cross section) of the image information display surface. Further, in any of the diagrams, the point t2 is the position where the image information display surface and the optical axis intersect (the optical axis position of the illumination light flux).

As is clear from FIG. 6, the light intensity of the illumination light flux decreases as the distance from the point t2 increases in the image information display surface, but the illumination light flux cross-section is deformed and the light intensity state in the illumination light flux is changed. As a result, the amount of strength reduction in the peripheral portion is greatly reduced as compared with the conventional example as shown in FIG. This is almost the same as that on the image information display surface of the light valve means, it is transformed into an intensity distribution state of the illumination light flux which is almost equalized.

Therefore, the difference in the intensity of the illumination light flux between the central portion and the peripheral portion on the image information display surface is reduced, so that the intensity unevenness is suppressed here. In other words, the irradiation light amount at the central portion of the image information display surface will be slightly lower than in the conventional case, but the irradiation light amount at the peripheral portion will be increased. This particularly contributes to the increase of the irradiation light amount at the end portion in the longitudinal direction, and the difference in intensity depending on the irradiation position is reduced, so that it is possible to irradiate an illumination light flux that is more uniform than in the past. .

Further, similarly to the above, since the cross section of the illumination light flux is elliptical corresponding to the image information display surface, the illumination light flux is applied to the entire image information display surface, and the effective irradiation light amount generally increases. ing. As a result, the image information spatially modulated on the image information display surface and imaged on the screen also has a large amount of projection light and becomes bright with less intensity unevenness. Furthermore, the brightness of the projected image is high, and uneven brightness is unlikely to occur.

Next, the invention described in claim 2 proposes a projection device provided with a light source means comprising a combination of a light source having a finite size in the illumination optical system and a light emitting portion and a concave mirror. . In the illumination optical system provided with such a light source means, the light intensity at each portion in the light flux cross section of the illumination light flux has a Gaussian distribution at the irradiation position of the illumination light (image information display surface of the light valve means).

That is, if the light source means in which the ideal light source is arranged at the focal position of the concave mirror is used, a parallel light flux having a predetermined light flux diameter can be obtained, but this is required for the light source means which is actually used in practice. It is almost impossible to do so, and there is a problem that the production cost rises to approach the ideal. for that reason,
A practical light source means is composed of a light source whose light emitting portion has a finite size, and a light source which is generally aligned with the focal position of the concave mirror.

Therefore, the light flux from the light source is not a perfect parallel light flux because the light from the location different from the focal position of the concave mirror in the light emitting portion is present, and the divergent or converged light components are mixed. There is. Therefore, it is usual to adjust the position of the light source with respect to the focal point of the concave mirror so that the light will be slightly focused as a whole.

Specifically, when the position of the light source is displaced from the concave mirror along the optical axis with respect to the focal position of the concave mirror, the illumination luminous flux emitted from the light source is
It is reflected so that it is almost focused on a certain point on the optical axis. The degree of light collection can be adjusted by adjusting the distance between the focal position of the concave mirror and the position of the light source.

Such an illumination light flux has a high irradiation light intensity (intensity) in the central portion at the irradiated position, and becomes an illumination light flux having a distribution close to a so-called Gaussian distribution. Therefore, by using the light source means in the illumination optical system of the present invention,
It becomes possible to suppress the light amount loss and convert the light into an illumination light flux whose intensity distribution is equalized.

The illumination optical system and the light source means comprising such a combination of the light source and the concave mirror have been widely known from the past, and the manufacturing cost can be kept low. Therefore, they are applied to the projection apparatus according to the present invention. Therefore, the manufacturing cost of the entire device can be reduced. Further, there is an advantage that the optical design is simple and the adjustment and the like can be easily performed.

Next, according to the invention described in claim 3 of the present application,
It is characterized in that the light flux cross-section deforming element enlarges the light flux cross section in the longitudinal direction of the image information display surface. The light flux cross-section deforming element according to the present invention includes one in which the light flux cross-section deformation direction expands in the longitudinal direction and one in which the light flux cross-section deformation direction shrinks in the lateral direction of the image information display surface. The invention can be carried out.

Due to a problem in device design, depending on the diameter of the luminous flux cross section of the illuminating luminous flux used in the illumination optical system and the size of the image information display surface of the light valve means, it is enlarged in the longitudinal direction or reduced in the lateral direction. You just have to decide.

For example, when the cross section of the light flux from the selected light source means is circular and the diameter of the light flux cross section is substantially equal to the length of the selected image information display surface in the longitudinal direction, the light flux cross section deforming element is It suffices to reduce the cross section of the light beam in the lateral direction.

Even when the image is shrunk in the lateral direction, as in the case of enlarging it in the longitudinal direction, in the irradiation area of the light flux irradiated toward the image information display surface, the area where the image information display surface is not irradiated. It is possible to improve the utilization efficiency of the light flux from the light source by reducing the area and the amount of light.

In the invention described in claim 4, the reason why the light beam cross-section deforming element expands the light beam cross section in the longitudinal direction of the image information display surface is based on the above-mentioned problem of the illumination optical system.

That is, if the luminous flux cross section is enlarged according to the image display surface, the luminous flux cross section of the illuminating light guided here is small, so that the light source means itself can be kept compact. In particular, if a concave mirror or the like is used as described above, the concave mirror itself can be made small, so that the manufacturing cost can be suppressed.

Further, by suppressing the light beam diameter to the element to be small, it is possible to suppress the partial loss light which is lost due to diffusion from the light source means. For this reason, it is possible to suppress the loss of the amount of light emitted from the element to the light valve means, and at the same time to suppress the loss of the amount of light when entering the element. Thereby, the utilization efficiency of the light flux from the light source can be further improved.

As described above, in the present invention, the luminous flux cross-section deforming element having the function of enlarging the luminous flux diameter is selected, and its enlarging direction is along the longitudinal direction of the image information display surface. As a result, the luminous flux reaches the portions such as the four corners of the image information display surface where it is difficult for the luminous flux to reach, suppressing dimming in the longitudinal direction and making the illumination luminous flux uniform over the entire image information display surface. Achieve the effect of being able to irradiate.

Therefore, the image information obtained by spatially modulating the illumination light flux applied to the image information display surface on the image information display surface to form an image by the image forming means also has an increased projection light amount. A bright image can be obtained on the screen.

Further, in the invention described in claim 4, when an illumination light flux having a general circular cross section is used, the size of the rectangular light valve means and the diameter of the illumination light flux (the size of the cross-sectional shape) The present invention provides a projection device that satisfies the conditions for irradiating the light valve means with the irradiation light flux most efficiently.

In summary, at the irradiation position, the cross section of the light flux from the light source means is enlarged so that the image information display surface of the light valve means is inscribed in the light flux cross-section contour deformed by the light flux cross-section deforming element. A projection device provided with a light beam cross-section deforming element is proposed.

The luminous flux cross-section deforming element provided in this projection apparatus has a circular luminous flux cross-section of the illumination luminous flux incident on the luminous flux cross-section deforming element, the luminous flux cross-section diameter is R, the enlargement magnification by the luminous flux cross-section deforming element is m, When the length of the image information display surface in the lateral direction is a and the length in the longitudinal direction is b, the following conditions are satisfied. R = √2 · am = b / a

By satisfying this condition, the contour of the luminous flux cross section deformed by the luminous flux cross-section deforming element (irradiation position or the contour of the irradiation area of the illumination luminous flux on the image information display surface).
In addition, since the outer contour (square portion) of the image information display surface is inscribed, the area where the image information display surface is not irradiated is minimized in the irradiation area of the illumination light flux irradiated toward the image information display surface. . Therefore, it is possible to minimize the light amount loss of the luminous flux emitted from the light source.

This will be described with reference to FIG. Considering a case where an illumination light flux having a circular cross section illuminates a square image information display surface, the amount of light loss is minimized when the square is inscribed in a circular irradiation area. If the length of one side of the square at this time is “a”, the diameter R of the circle at this time is “√2
・ It becomes "a".

In this state, "b /
When enlarged by “a” times, the square becomes a rectangle having a short side length “a” and a long side length “b”. If the circle is expanded in the same direction at the same time, the ratio of the long axis to the single axis is "b / a".
, And the inscribed state of both is maintained.

As is apparent from this fact, the diameter R is “√2 · a” with respect to the rectangular image display surface having the short side length “a” and the long side length “b”. The elliptical irradiation area obtained by enlarging the circular irradiation area by “b / a” times in the long side direction (longitudinal direction) covers the entire image display surface and is inscribed when the centers are aligned.

FIG. 7 shows an example in which the illumination light flux from the light source has a distribution close to a Gaussian distribution. In this figure, the image information display surface 75 is inscribed in the illumination light flux irradiation area 78. The relative positional relationship of the image information display surface 75 is defined. Then, similarly to the above, the shaded area x is an area where the image information display surface 75 is not irradiated, and the circle in the irradiation area 78 of the illumination luminous flux is a contour-like explanatory line representing the light intensity distribution state.

As is clear from this figure, by guiding the irradiation area of the illumination light flux so that the image information display surface 75 is inscribed,
Since the area of the region x is the minimum, the light amount loss of the illumination light flux is also the minimum.

Further, here, an illumination light flux having a distribution close to a Gaussian distribution is shown, but in this case, since the light intensity of the light flux irradiated on the image information display surface 75 becomes relatively weak at the peripheral portion, irradiation is performed. The amount of light emitted to the region x occupying the outer side of the region 78 is reduced, and the image information display surface 75
Since the light amount of the illumination light flux for illuminating is increased, it is possible to further suppress the light amount loss and illuminate the entire image information display surface 75 with the illumination light flux with a substantially uniform intensity.

As a result, the image information obtained by spatially modulating the illumination light flux applied to the image information display surface on the image information display surface to form an image by the image forming means also has an increased light quantity. A bright image can be obtained on the screen.

Needless to say, even if the light flux cross-section deforming element that strictly satisfies the above formula is not used, the light flux cross-section modification that expands the diameter of the illumination light flux so that the image information display surface is inscribed to the contour of the light flux cross-section after the deformation is performed to some extent. A sufficient effect can be obtained as an element.

The outline of the cross section of the light flux here is synonymous with the outline of the irradiation area of the illumination light flux on the image information display surface. It also shows the range that can be obtained. In other words, the region where the illumination light having the intensity necessary for forming the image by the spatially modulated light from the light valve means is formed by the irradiation light (effective Illumination area).

Further, when the cross section of the luminous flux of the illumination light is reduced in the lateral direction of the image information display surface, it is preferable to satisfy the following conditions. R = √2 · b m = a / b

On the contrary, by satisfying this condition and reducing the size, the irradiation area by the illumination light beam after the reduction deformation is inscribed in the four corners of the image information display surface, and the light quantity loss due to this irradiation is reduced. It is the smallest. This is effective, for example, when manufacturing the projection apparatus according to the present invention, when the cross-sectional diameter of the illumination light flux from the selected light source means is larger than the size of the image information display surface of the selected light valve means.

Next, in the invention described in claim 5,
Since the light flux cross-section deforming element including the prismatic optical element is used, the diameter of the light flux cross-section of the illumination light flux is deformed in one direction by utilizing the refraction effect of the prism. As a light flux cross-section deforming element, it is the simplest, the design is easy, the cost is low, and the availability is low.

Here, in FIG. 8, as a light beam cross-section deforming element,
An example of using a prism element is shown. Of course, the prismatic element is not limited to this shape. In FIG. 8, the beam A (light flux from the light source) incident from the incident surface 81 a of the prismatic element 81 is refracted in the prismatic element 81, and exited surface 81 b of the prismatic element 81.
More shot. The emitted beam B (illumination light flux toward the light valve means) is obtained by expanding the diameter of the beam A in a direction including the paper surface (lateral direction parallel to the paper surface).

Here, when the light is emitted vertically from the emission end face, the diameter of the beam A is α, the diameter of the beam B in the longitudinal direction is β, the apex angle of the prism-shaped element 81 is φ, and the prism-shaped element 81. Letting θ be the incident angle of the beam A with respect to the incident surface of, the beam expansion rate m is expressed as follows. m = β / α or m = cosφ / cosθ

At this time, if it is not necessary to vertically emit the light from the exit surface, the beam expansion rate m can be adjusted by changing the incident angle θ of the beam A. As described above, the diameter α of the beam A, the apex angle φ of the prism-shaped element 81, and the incident angle θ of the beam A with respect to the incident surface of the prism-shaped element 81 are selected or adjusted as appropriate to change the image information. The size of the light beam diameter (cross-sectional shape) of the beam B, which becomes the light beam irradiated to the display surface, can be adjusted.

On the other hand, if the beam B is traced backward, the beam diameter can be reduced to 1 / m. Therefore, in order to reduce the beam, the light beam may be incident so as to follow the reverse of the optical path shown in FIG. Then, preferably, by appropriately selecting or adjusting each of them so as to satisfy the above-mentioned deformation conditions, the four corners of the image information display surface are adjusted so as to be inscribed in the irradiation region of the beam B, and the sectional shape of the illumination light beam is adjusted. Should be enlarged or reduced.

The light flux cross-section deforming element applied to the present invention is not limited to the prism-shaped element, and is, for example, a light-transmitting member such as a cylindrical lens or a reflecting mirror having a cylindrical reflecting surface ( Even if a light-reflecting member such as a cylindrical mirror) is used, a sufficient effect can be obtained. In the case of the present invention, there is an advantage that the lens interval and the optical axis shift can be rough compared to these methods.

By the way, not limited to the prism-shaped element,
The light flux cross-section deforming element used in the present invention preferably satisfies an achromatic condition corresponding to the illumination light flux of the illumination optical system. This is because color unevenness may occur on the light valve means by giving an optical change to the illumination light flux, and there is an effect of preventing these and obtaining good illumination light.

To satisfy this achromatic condition, for example, an achromatic prism in which two prisms having different dispersion ratios are combined and bonded together, or an achromatic lens in which two lenses are similarly combined (a combination of concave and convex cylindrical lenses, etc.) ) And the like are known, but not limited to these, other achromatic conditions may be satisfied. There is no concern about chromatic aberration if the combination of the cylindrical mirrors is used.

With such a structure, a clear projection image can be obtained by the illumination light without color unevenness in which the chromatic aberration generated by the prismatic element or the like is suppressed.

[0103]

The present invention will be described in more detail with reference to the following examples. FIG. 1 shows a schematic configuration of a projection apparatus according to the first embodiment of the present invention. In the first embodiment, the illumination optical system is the light source 101.
And a condenser lens 103 having a reflecting portion of a spheroidal surface, and a prism 104 which is a beam cross-section deforming element is provided on the optical path of the illumination optical system.

In the first embodiment, the light source 101 uses a metal halide lamp, and the light emitting section is a light source having a length of several millimeters. Of course, another white light source such as a xenon lamp may be used.

When the light emitting portion of the light source 101 is arranged and combined at the focal position of the reflecting mirror 102, the light emitted from the focal position of the reflecting mirror in the light emitting portion of the light source 101 travels toward the reflecting mirror 102. Then, it is reflected here and becomes focused light.

Then, after the light is focused on one point on the optical axis of the reflecting mirror 102, it proceeds again while diverging, and enters the condenser lens 103. The focal position of the condenser lens 103 is aligned with the condensing position, and the luminous flux reflected by the reflecting mirror 102 and incident thereon is converted into parallel light and emitted.

The illumination light flux emitted from the condenser lens 103 enters a prism 104 which is a light flux cross-section deforming element. However, in reality, since the light emitting portion of the light source 101 has a finite size, it is arranged at a position slightly deviated from the focal position of the reflecting mirror 102. As a result, the illumination light flux emitted from the light source 101 has an intensity distribution in a distribution state close to a Gaussian distribution and is applied to the image information display surface.

The illumination light flux emitted from the condenser lens 103 has its optical path bent by the prism 104 disposed on the optical path, and at the same time, the diameter of the light beam is expanded in the bending direction. The illumination light flux emitted from the prism 104 is vertically emitted from the emission surface, and its cross-sectional shape is adjusted so that the square portion of the image information display surface of the light valve 105 is inscribed in the irradiation area. .

Here, the enlargement magnification m of this prism 104
₁ is determined according to the aspect ratio of the projected image information display surface (aspect ratio, horizontal direction parallel to the paper surface). In the first embodiment, since the aspect ratio of the image information display surface of the light valve 105 is horizontal: vertical = 4: 3, the enlargement magnification m ₁ is m ₁ = 4 / 3≈1. It is preferable to set it to 33.

The magnification m ₁ is equal to that of the prism 10
4 is determined by the apex angle φ ₁ and the incident angle θ ₁ of the illumination light flux with respect to the incident surface of the prism 104.
When the enlargement ratio m ₁ is expressed by the relational expression between them, m ₁ = co
It is expressed as sφ ₁ / cos θ ₁ .

[0111] The magnification m ₁ is, m ₁ as described above
Since it is most preferable to set = 4 / 3≈1.33,
m ₁ ≒ 1.33 = so as to satisfy the cos [phi ₁ / cos [theta] _1, the apex angle phi ₁ of the prism 104, and determines the incident angle theta ₁ of the beam relative to the incident surface of the prism 104. Further, the cross-sectional shape of the illumination light flux emitted from the condenser lens 103 is circular, and its diameter R ₁ is √2 of the length in the vertical direction of the image information display surface (single hand direction, direction perpendicular to the paper surface).
It has been adjusted to double.

The aspect ratio of the image information display surface used in the projection apparatus according to the present invention is not limited to this, and can be freely set, for example, "horizontal: vertical = 16: 9". Is. Therefore, it goes without saying that the apex angle φ of the prism to be used, the incident angle θ of the illumination light beam with respect to the incident surface of the prism, the cross-sectional diameter of the illumination light beam incident on the prism, etc. are determined in accordance with the set aspect ratio.

In the first embodiment, this prism 104
In the above, the illumination luminous flux is expanded in the longitudinal direction of the image information display surface, that is, in the lateral direction, but of course, the illumination luminous flux may be contracted in the lateral direction of the image information display surface, that is, in the longitudinal direction. In the configuration of the first embodiment, in order to reduce the illumination light flux in the lateral direction of the image information display surface, that is, in the vertical direction, the enlargement magnification m ₁ is set to m ₁ = 3/4 = 0.75, and the light is incident there. The cross-sectional diameter of the light beam may be √2 times the length of the image information display surface in the longitudinal direction.

The image display surface of the light valve 105 partially changes the luminous flux emitted from the light source with a constant intensity according to the input signal, and spatially modulates a part of the luminous flux reflected here. . In this embodiment, as the light valve 105, the reflection type is arranged, but the light valve 105 is not limited to the reflection type and may be a transmission type.

The light valve has, for example, a structure in which the surface of an oil film or a metal film is deformed by electronic means,
Examples thereof include those provided with the image information display surface made of electro-optic crystal such as liquid crystal, but are not limited to this configuration.

The light flux reflected by the light valve 105 is spatially modulated according to the image information on the image information display surface, and is projected by the imaging lens 106 to form an image. At the image forming position by the imaging lens 106,
A screen 107 is provided, and the light valve 10
The illumination luminous flux spatially modulated according to image information by 5 is
The image formed by the image forming lens 106 is projected on the screen 107.

As described above, in the present embodiment, the irradiation area of the illumination light beam is deformed and irradiated, thereby minimizing the area of the non-irradiation area on the image information display surface, and the light quantity of the light beam emitted from the light source. Minimize loss. further,
Since the light quantity distribution state in the cross section of the light flux is also deformed, the illumination light flux of substantially equalized intensity is emitted regardless of the irradiation position on the image information display surface. Then, with such a simple configuration, it is possible to obtain a good image in which the light amount of the image projected on the screen is increased and the intensity difference (or intensity unevenness) on the image is small.

In the prism 104 in FIG. 1, the cross-sectional shape of the illumination light beam is enlarged in the direction parallel to the paper surface, but in this projection device, the illumination light beam is obliquely applied to the image information display surface of the light valve 105. Therefore, the cross-sectional shape orthogonal to the optical axis of the illumination luminous flux and the shape of the irradiation region are different. Therefore, the deformation amount of the light flux cross section is adjusted in consideration of the shape deformation (with respect to the light flux cross section) of the irradiation region due to the oblique incidence.

Next, FIG. 2 shows a schematic structure of a projection apparatus according to the second embodiment of the present invention. In this embodiment, the illumination optical system is composed of a light source 201, a parabolic mirror 202 composed of a paraboloid of revolution, a condenser lens 203, and the like, and a prism 204 which is a beam cross-section deforming element is provided on the optical path of the illumination optical system. Has been.

The light emitting portion of the light source 201 is the parabolic mirror 20.
Of the light emitted from the light source 201, all of the light traveling toward the parabolic mirror 202 is reflected at the parabolic mirror 202 and is parallel to one direction. Proceed to. In the second embodiment, the direct light from the light source and the reflected light are used as the illumination luminous flux. In the second embodiment, a xenon lamp is used as the light source 201, but any white light source such as metal halide can be applied to this embodiment.

Since the light emitting portion of the light source 201 has a finite size as in the above embodiment, it is arranged at a position slightly deviated from the focus position of the parabolic mirror 202. Therefore, when the illumination light flux emitted from the light source 201 and incident on the parabolic mirror 202 is reflected by the parabolic mirror 202,
It is reflected so that it becomes a little focused light. Therefore, the light intensity of the illumination light flux on the light valve at each portion in the light flux cross section has a distribution close to a Gaussian distribution.

Then, this illumination luminous flux is transmitted through the parabolic mirror 202.
Due to this, the light flux becomes a substantially parallel light flux, travels, and enters the prism 204 which is a light flux cross-section deforming element. This prism 204 is arranged so that the cross-sectional shape (irradiation region) of the light beam incident from the light source direction is inscribed in the image information display surface of the light valve 205, as shown in FIG. (Longitudinal direction or lateral direction) in only one direction. As a result, the area of the region where the image information display surface is not illuminated is minimized, and the light amount loss of the light flux emitted from the light source is minimized.

The magnification m ₂ of the prism 204 is determined according to the aspect ratio of the image information display surface to be projected. In the second embodiment, the aspect ratio of the image information display surface is horizontal: vertical = 16: 9, and therefore the enlargement ratio m ₂
Is preferably m ₂ = 16 / 9≈1.78. In addition, the magnification m ₂ is determined by the apex angle φ ₂ of the prism 204 and the incident angle θ ₂ of the illumination light beam with respect to the incident surface of the prism 204 when the light is vertically emitted from the emitting surface. When the enlargement factor m ₂ is expressed by the relational expression between the _two , m ₂ = cos φ ₂ / cos θ ₂ .

Therefore, the magnifying power m _{2 of the} prism 204 is increased.
As described above, so that m ₂ = 16 / 9≈1.78 (under the condition that m ₂ ≈1.78 = cos φ ₂ / cos θ ₂ is satisfied), and the apex angle φ _{2 of the} prism 204, The incident angle θ ₂ of the illumination light flux with respect to the incident surface of the prism 204 is determined.

In other words, in the prism 204 in the second embodiment, the cross-sectional shape of the light beam incident from the light source side is set to 1. Only in the lateral direction of the image information display surface (direction parallel to the paper surface).
It is magnified 78 times and the apex angle φ of the prism 204
₂ and the incident angle θ ₂ of the illumination light flux with respect to the incident surface of the prism 204 are determined by the enlargement magnification 1.78.

The cross-sectional diameter R ₂ of the illumination light flux incident on the prism is √2 times the vertical length of the image information display surface (length in single hand direction, length in vertical direction on paper). The size and reflection direction of the reflecting mirror 201 of the light source means are constructed. In the second embodiment, this prism 2
Reference numeral 04 enlarges the illumination light flux in the longitudinal direction of the image information display surface, that is, the horizontal direction, but of course, may reduce the illumination light flux in the short direction of the image information display surface, that is, the vertical direction.

In the case of the reduction deformation type having the same configuration as the second embodiment, in order to reduce the illumination light flux in the lateral direction of the image information display surface, that is, in the vertical direction, the enlargement magnification (reduction ratio) m ₂ is set to m.
_It is preferable that ₂ = 9/16 = 0.56. In this case, it is desirable that the cross-sectional diameter R ₂ of the illumination light flux entering the prism is √2 times the lateral length (longitudinal length) of the image information display surface. As a result, the illumination optical system is a reduction-deformation type and has the least light amount loss.

The aspect ratio of the image information display surface used in the projection apparatus of the present invention is not limited to the above and can be freely set. It goes without saying that the apex angle φ of the prism to be used and the incident angle θ of the illumination light beam with respect to the incident surface of the prism are determined according to the set aspect ratio.

The image information display surface of the light valve 205 is one that partially spatially modulates the illuminating light flux in accordance with the input signal (so-called transmissive light valve). An image can be obtained by focusing the formed light flux.

When passing through this light valve 205,
The illumination light flux spatially modulated according to the image information displayed on the image information display surface enters the imaging lens 206 and is projected on the screen 207 to form a projected image. Although the transmissive light valve is used in the second embodiment, it is also possible to use the illumination optical system according to this embodiment in combination with the reflective light valve.

As the transmissive light valve used in this embodiment, for example, a simple matrix type liquid crystal,
An active matrix type liquid crystal is mentioned. Since the former simple matrix type liquid crystal has a simple structure, there is an advantage that the illumination optical system of the present invention can be constructed as a simple structure, and the latter active matrix type liquid crystal has a response speed higher than that of the former one. The advantage is that an illumination optical system with better performance can be obtained because of high speed and high contrast. Needless to say, the present invention is not limited to the transmissive light valve having this configuration, and one suitable for the purpose of use can be appropriately selected and used.

As described above, in the projection apparatus according to the second embodiment, since the parabolic mirror is used as the reflecting mirror, the light flux from the illumination can be made substantially parallel when reflected, so that the illumination optical system There is an advantage that the projection device can be constructed with a simpler configuration by reducing the number of constituent members. Further, even with such a simple configuration, it is possible to guide the illumination light flux to the light valve while minimizing the light amount loss of the light flux emitted from the light source.

Further, since the light quantity of the image projected on the screen is larger than that of the conventional one, there is an advantage that a bright image can be obtained. On the contrary, in order to obtain an image of the same level as the conventional one, a light source having a smaller amount of light than that of the conventional device can be used, so that the device can be downsized and the manufacturing cost can be reduced.

Next, FIG. 3 shows a schematic structure of a projection apparatus according to the third embodiment of the present invention. In the third embodiment shown in FIG. 3, the illumination optical system includes a light source 301, a spherical mirror 302 having a hemispherical surface, a condenser lens 303, and the like. It is located on the street.

When the light emitting portion of the light source 301 is arranged at the focus (center) position of the spherical mirror 302 and combined, the light source 30
Of the light emitted from the light source 1, all of the light traveling toward the spherical mirror 302 is specularly reflected by the spherical mirror 302 and returns to the light emitting portion again.
It becomes a light beam that diverges in directions other than 2.

Therefore, if a condenser lens 303 whose focal position is aligned with the light emitting portion of the light source 301 (the center position of the spherical mirror 302) is arranged on the opposite side of the spherical mirror 302, the light source 301 is caused to emit by the condenser lens 303. Almost all of the emitted light travels in a substantially parallel direction in a predetermined direction. In the third embodiment, the light flux converted into parallel light here is used as the illumination light flux.

By the way, since the light emitting portion of the light source 301 has a finite size, the spherical mirror 302 and the light source 301 are actually slightly displaced from the condenser lens 303 with respect to the focal position of the condenser lens 303. Are arranged. Therefore, the condenser lens 303
This prevents the generation of shadows in the vicinity of the optical axis of the illumination light flux emitted from, and provides an illumination light flux having a distribution close to a so-called Gaussian distribution.

Although the metal halide lamp is used as the light source 301 in the third embodiment, it is not particularly limited as long as it is a white light source such as a xenon lamp. Further, the condenser lens 303 is for collimating the incident illumination light flux and for emitting it, and is not particularly limited as long as it has this function.

Next, a prism 304 is provided on the optical path of the above-mentioned illumination light beam, and the cross-sectional shape of the light beam incident from the light source direction is enlarged and deformed only in the direction parallel to the paper surface.
Specifically, the irradiation area of the illumination light flux is the light valve 30.
The light beam cross-sectional diameter is enlarged in the longitudinal direction of the image information display surface (the paper surface direction in FIG. 3) so that the image information display surface 5 is inscribed. As a result, the area of the region where the image information display surface is not illuminated is minimized, and the light amount loss of the light flux emitted from the light source is minimized.

Here, the cross-sectional diameter of the illumination light flux before entering the prism 304 is √ of the length of the image information display surface in the single-handed direction.
Reflecting mirror 302 and condenser lens 30
The size of 3 is adjusted. Also, this prism 3
The enlargement ratio m _{3 of} 04 is determined according to the aspect ratio of the projected image information display surface. The aspect ratio of the image information display surface of the light valve 305 used in the third embodiment is horizontal: vertical = 16. : 9, and the magnification m ₃ = 16/9
It is preferable that ≈1.78.

Further, this magnification m ₃ is determined by the apex angle φ ₃ of the prism 304 and the incident angle θ ₃ of the illumination light flux with respect to the incident surface of the prism 304 when the light is vertically emitted from the emitting surface. Therefore, when the enlargement magnification m ₃ is represented by the relational expression between them, m ₃ = cos φ ₃ / cos θ ₃
Becomes

This magnification m ₃ is m ₃ =
Since it is the most preferable that 16 / 9≈1.78,
The apex angle φ ₃ of the prism 304 and the incident angle θ ₃ of the illumination light flux with respect to the incident surface of the prism 304 are determined so that m ₃ ≈1.78 = cos φ ₃ / cos θ ₃ is satisfied.

That is, the prism 304 in the third embodiment.
Is for enlarging the cross-sectional shape of the light beam incident from the light source side by 1.78 times in the lateral (longitudinal) direction of the image information display surface. Further, the apex angle φ ₃ of the prism 304 and the prism 304 The incident angle θ ₃ of the illumination light flux with respect to the incident surface is determined by the enlargement factor 1.78.

In the third embodiment, this prism 30
Reference numeral 4 enlarges the illumination light flux in the longitudinal direction, that is, the horizontal direction of the image information display surface, but of course, it may also reduce the illumination light flux in the short direction, that is, the vertical direction of the image information display surface. In the case of the configuration similar to that of the third embodiment, the luminous flux diameter of the illumination luminous flux incident on the prism is set to √2 times the length in the longitudinal (horizontal) direction of the image information display surface, and the short side (vertical length) of the image information display surface is set. ) Direction, enlargement ratio (reduction ratio) m ₃ =
It is preferable that 9/16 = 0.56.

The aspect ratio of the image information display surface used in the projection apparatus of the present invention can be freely set as in the above embodiment, and the apex angle φ of the prism to be used is set according to the set aspect ratio. The incident angle θ of the illumination light beam with respect to the incident surface of the prism, the illumination light beam diameter, etc. may be determined.

Further, the light valve 3 in the third embodiment.
Although 05 is a so-called reflective type, it is not limited to this and may be a transmissive type. Furthermore, examples of the reflection type light valve include one having a structure in which the surface of an oil film or a metal film is deformed by electronic means, one having the image information display surface made of an electro-optical crystal such as liquid crystal, and the like. However, the present invention is not limited to this configuration.

Next, in the third embodiment, the light beam reflected by the light valve 305 is spatially modulated according to the image information on the image information display surface, and is incident on the imaging lens 306 as it is. Then, the image is formed on the screen 307 by the imaging lens 306 to form a projected image. As described above, also in the third embodiment, it is possible to project the light flux emitted from the light source on the screen with a minimum light loss with a simple configuration.

Further, in the above-mentioned three embodiments, the prism is mentioned as an example of the light beam cross-section deforming element. With such a structure, the cross section of the incident light beam can be easily deformed in one direction. Depending on the type of light source, chromatic aberration may occur due to the color dispersion of the prism.

Therefore, an example in which the chromatic aberration is corrected by using an achromatic prism as the prism used as the beam cross-section element is shown in FIG. 4 as a fourth embodiment. In the fourth embodiment, the illumination light beam 410 is transmitted by the first prism 41.
The chromatic aberration that occurs when the light enters the first prism 414
It is configured to be corrected by making the light incident on the second prism 424 disposed after the.

In this embodiment, the first prism 41
4, the enlargement ratio is m ₁ , the bending ratio is n ₁ , and the bending ratio dispersion is δn.
₁ , the expansion ratio of the second prism 424 is m ₂ , and the bending ratio is n
_{2. When} the inflection ratio dispersion is δn ₂ , if these satisfy the formula (1) shown below, it is possible to satisfy the achromatization requirement (to suppress the chromatic aberration generated due to dispersion by the first prism). (Δn ₁ / δn ₂ ) ² = m ₁ ² {(n ₁ ² -1) (m ₂ ² -1)} / {(n ₂ ² -1) (m ₁ ² -1)} ... ( 1) formula

That is, in FIG. 4, the illumination light beam 410 emitted from the light source (not shown) is made substantially parallel and enters the first prism 414. In the first prism 414, the cross-sectional shape of the incident light flux is deformed in the longitudinal direction of the light valve (not shown). At that time, the illumination light flux is dispersed for each wavelength possessed by the illumination light flux and is emitted with chromatic aberration occurring, The light enters the two prisms 424.

First prism 414 and second prism 424
Is assumed to satisfy the condition of the equation (1) described above, the illumination light beam 410 incident on the second prism 424 is
The chromatic aberration generated by the first prism 414 is corrected and the illumination light flux is emitted.

If two prisms having exactly the same magnifying power, bending ratio, and bending dispersion are used, the chromatic aberration can be suppressed to a very small value, though it is not completely φ. The achromatic prism of this embodiment can be constructed. Since the same prisms are arranged in two opposite directions, as shown in FIG. 4, the illumination light flux is emitted parallel to the incident direction after the cross-sectional diameter of the illumination light flux is enlarged and deformed.

As described above, by using two prisms and setting the magnifying power, the bending ratio, and the bending dispersion of each prism so as to satisfy the above equation (1), chromatic aberration can be easily corrected. At the same time, it is possible to minimize the area of the region that does not illuminate the image information display surface to minimize the light amount loss of the light flux emitted from the light source.

FIG. 5 shows an example in which a light flux cross-section deforming element is constructed by bonding three prisms having different bending ratio dispersions so that the illumination light flux transmitted through the light flux cross-section element does not cause chromatic aberration. . In FIG. 5, an illumination light flux 5 emitted from a light source means (not shown) and substantially collimated
10 is incident on the compound prism 514, which is a light flux cross-section element, from the left side toward the paper surface.

This composite prism 514 is formed by adhering three prism elements having different dispersions of the bending ratio with a balsam or the like, and when the illumination light beam 510 passes through the composite prism 514, each prism element The chromatic aberrations produced are canceled by each other, and light beams having no chromatic aberration are emitted to the compound prism 514.

FIG. 5 shows an example in which three prisms having different bending ratio dispersions are bonded together, but the present invention is not limited to this. For example, the same magnifying power and
It may be a combination of two prisms having a bending rate and a bending dispersion.

Thus, by adhering a plurality of prisms each satisfying an achromatic condition to form one element, chromatic aberration can be easily corrected at low cost, and at the same time, on the image information display surface. It is possible to minimize the area of the region not irradiated with and to minimize the light amount loss of the luminous flux emitted from the light source.

Further, as long as the illumination light flux is passed through a plurality of prisms which meet the achromatic conditions, even if the illumination light fluxes are arranged in order without being adhered, the present invention is sufficiently satisfied. It is not limited to the method of this embodiment.

Further, FIG. 11 shows a schematic configuration of a projection apparatus according to the sixth embodiment of the present invention when a cylindrical lens is used as the light beam cross-section deforming element. In this example,
The illumination optical system includes a light source 601 and a parabolic mirror 602 having a paraboloid of revolution, and a cylindrical concave lens 604a and a cylindrical convex lens 604b, which are light flux cross-section deforming elements, are provided on the optical path of the illumination optical system. The focal lengths and lens arrangement intervals of these two cylindrical lenses 604a and 604b are arbitrarily determined as needed.

The light emitting portion of this light source 601 is a parabolic mirror 60.
Of the light emitted from the light source 601, all of the light traveling toward the parabolic mirror 602 is reflected at the parabolic mirror 602 and is parallel to one direction. Proceed to. In the sixth embodiment, the direct light from the light source and the reflected light are used as the illumination luminous flux. In this sixth embodiment, a xenon lamp is used as the light source 601, but any white light source such as metal halide can be applied to this embodiment.

Further, since the light emitting portion of the light source 601 has a finite size as in the above-mentioned embodiment, the parabolic mirror 602 is provided.
It is arranged at a position slightly deviated from the focal position of. Therefore, the illumination light flux emitted from the light source 601 and incident on the parabolic mirror 602 is reflected so as to be a little converging light when reflected by the parabolic mirror 602. Therefore, the light intensity of the illumination light flux on the light valve at each portion in the light flux cross section has a distribution close to a Gaussian distribution.

Then, this illumination luminous flux is transmitted through the parabolic mirror 602.
Then, the light flux becomes a substantially parallel light flux, travels, and enters the cylindrical concave lens 604a forming the light flux cross-section deforming element. This cylindrical concave lens 604a is arranged so that the image information display surface of the light valve 605 inscribes the cross-sectional shape (irradiation region) of the light beam incident from the light source direction in the paper surface direction (direction parallel to the paper surface, image information display) in FIG. It extends only in one direction in the longitudinal or lateral direction of the plane).

The light beam emitted from the cylindrical concave lens 604a diverges so that the cross-sectional shape of the light beam expands in an arbitrary direction, and the cylindrical convex lens 604b.
Incident on. This cylindrical convex lens 604b is
In order to collimate the light flux diverging in the expansion direction, the divergent light flux incident on the cylindrical convex lens 604b is collimated and emitted toward the light valve 605.

The light beam incident on the light valve 605 is spatially modulated according to image information when passing through the light valve 605. The spatially modulated light flux enters the imaging lens 606 and is projected on the screen 607 by the imaging lens 606 to form a projected image. Although the transmission type light valve is used in the sixth embodiment, it is also possible to use the illumination optical system according to this embodiment in combination with the reflection type light valve.

As described above, by combining the cylindrical concave lens and the cylindrical convex lens, the irradiation area by the illumination light beam can be deformed.
The area of the non-irradiated area on the image information display surface is minimized to minimize the light amount loss of the light flux emitted from the light source.

Further, since the light quantity distribution state in the cross section of the light flux is also modified, the illumination light flux of substantially equalized intensity is emitted regardless of the irradiation position on the image information display surface. . Then, with such a simple configuration, it is possible to obtain a good image in which the light amount of the image projected on the screen is increased and the intensity difference (or intensity unevenness) on the image is small.

Further, in the sixth embodiment of the present invention, the cylindrical concave lens and the cylindrical convex lens are arranged on the optical path, but the present invention is not limited to this, and if possible, these two cylindrical lenses may be bonded together. It may be used as one light flux cross-section deforming element.

[0169]

As described above, according to the present invention, it is possible to easily change the cross section of a light beam in any direction such as the vertical direction or the horizontal direction according to the shape of the image information display surface of the light valve. Is. As a result, the area of the region of the illumination light flux that does not illuminate the image information display surface can be suppressed to be small, and thus the light amount loss of the illumination light flux emitted from the light source can be reduced.

Therefore, it is possible to obtain a projection device which can use the light emitted from the light source with high efficiency. Further, as compared with the conventional example, since the irradiation light amount increases by the amount of the loss light amount decreased, the intensity of the illumination light to the light valve increases and the brightness of the projected image also increases. Further, the brightness of the projected image is increased due to the increase of the irradiation intensity to the light valve. By these, it becomes possible to construct a projection device with improved image projection characteristics.

Further, even if an illuminating means having a distribution close to a so-called Gaussian distribution (or a Gaussian distribution) is used, the amount of light reduction (irradiation intensity difference) that occurs as the distance from the center of the optical axis in the image information display surface of the light valve increases. Can be significantly reduced as compared with the conventional one. With this, it is possible to irradiate the entire surface of the light valve with the illumination light flux with uniform intensity.

Further, since the image information display surface is illuminated by the illumination light flux having such uniform intensity, unevenness in the intensity of the projected image projected from here is unlikely to occur, and in particular, the brightness of the peripheral portion and the central portion of the image is reduced. Since the difference is small, a good image can be obtained. Further, since the illumination light flux having such a uniform intensity can be obtained, uneven brightness in the projected image is less likely to occur.

In the invention described in claim 2, since the same illumination optical system as in the conventional apparatus is applied, there is an advantage that the design and adjustment of the optical system are easy and the manufacturing cost is suppressed.
There is also an advantage that the projection apparatus according to the present invention can be constructed by simply modifying the conventional apparatus.

On the other hand, by combining with such an illumination optical system, even if the structure is simple and the assembly accuracy is rough, the luminous flux cross-section deforming element corrects the intensity distribution generated in the luminous flux cross section, It is possible to obtain a projection device including an illumination optical system that maintains the intensity uniformity over the entire irradiation area.

According to the invention described in claim 3, since the light flux cross section is enlarged and deformed in the longitudinal direction of the light valve, the amount of light loss can be further reduced, and at the same time, the dimming at the end portion in the longitudinal direction (center The strength difference from the part),
It is possible to obtain a projection device including an illumination optical system that can uniformly illuminate the image information display surface.

In the invention described in claim 4, since the deformation condition by the light beam cross-section deforming element is set, the amount of light loss at the time of illuminating the light valve can be minimized by constructing the illumination system according to this condition. It will be possible.

In the invention described in claim 5, since the prismatic optical element is used as the light beam cross-section deforming element, there is an advantage that the projection apparatus according to the present invention can be constructed with a low cost and a simple structure.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a projection device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a schematic configuration of a projection device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a schematic configuration of a projection device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram that satisfies an achromatic condition of a light beam cross-section deforming element used in the projection apparatus of the present invention.

FIG. 5 is a configuration diagram of a bonding example that satisfies the achromatic condition of the light flux cross-section deforming element used in the projection device of the present invention.

FIG. 6 is a diagram showing the light intensity when an illumination light flux having a Gaussian distribution is deformed in the longitudinal direction of the image information display surface and is applied to the rectangular image information display surface.

FIG. 7 is a schematic diagram of a case where an illumination light beam whose light beam cross-sectional shape is deformed in the longitudinal direction by a light beam cross-section deforming element of the present invention is illuminated so that a rectangular image information display surface is inscribed.

FIG. 8 is an explanatory diagram of elements that determine conditions of the light beam cross-section deforming element in the present invention.

FIG. 9 is a schematic diagram when an illumination light flux having a circular light flux cross-section is illuminated on a rectangular image information display surface.

FIG. 10 is a diagram showing a light intensity when an illumination light flux having a Gaussian distribution is applied to a rectangular image information display surface.

FIG. 11 is an explanatory diagram showing a schematic configuration of a projection device according to a sixth embodiment of the present invention.

[Explanation of symbols]

101, 201, 301, 601 Light source 102 Elliptical reflecting mirror 202, 602 Parabolic mirror 302 Spherical mirror 103, 203, 303 Condenser lens 104, 204, 304 Prism 604a Cylindrical concave lens 604b Cylindrical convex lens 105, 205, 305, 605 Light valve 106, 206, 306, 606 Imaging lens 107, 207, 307, 607 Screen 410, 510 Illumination luminous flux 414 First prism 424 Second prism 514 Composite prism 75, 95 Image information display surface 78, 98 Illumination luminous flux irradiation area x , Y Areas where the image information display surface is not illuminated t1, t2 Intersection points of the image information display surface and the mirror axis 81 Prism element 81α Incident surface of prism element 81β Exit surface of prism element A Incident on prism element Light flux α Diameter of light flux incident on prismatic element B Light flux emitted by prismatic element β Diameter in the longitudinal direction of light flux emitted by prismatic element φ Vertical angle of prismatic element θ Incident on incident surface of prismatic element Incident angle of light flux

Claims (5)

[Claims] 1. A light valve means for spatially modulating a light beam emitted for displaying a two-dimensional image, an illumination optical system for irradiating an image information display surface of the light valve means with an illumination light beam from a light source means, Image forming means for forming an image of the illumination light flux spatially modulated on the image information display surface of the light valve means on the projection surface;
A projection apparatus, comprising: a light flux cross-section deforming element that transforms a light flux cross section of the illumination light flux in a predetermined direction in an optical path of the illumination optical system. 2. The illumination optical system comprises a light source means comprising a combination of a light source whose light emitting portion has a finite size and a concave mirror which reflects a light beam from the light source and guides it toward the light valve means. The projection device according to claim 1, wherein the projection device is provided. 3. The light flux cross-section deforming element enlarges the light flux cross section in the longitudinal direction of the image information display surface of the light valve means.
The projection device according to. 4. The luminous flux cross-section deforming element, when the luminous flux cross-section of the illumination luminous flux incident on the luminous flux cross-section deforming element is circular, the luminous flux cross-sectional diameter of the illuminating luminous flux is R, and the enlargement magnification by the luminous flux cross-section deforming element. The following conditions are satisfied, where m is m, the length of the image information display surface in the lateral direction is a, and the length in the longitudinal direction is b. Projection device. R = √2 · am = b / a 5. The projection apparatus according to claim 1, wherein the light beam cross-section deforming element is a prismatic optical element.