JP2000321527A - Optical projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a projection image above the installation surface of the optical projector and to reduce the manufacture cost without widening an effective image circle. SOLUTION: The light emitted by a light source and a lighting optical system passes through an optical modulation layer 9 and enters a projection optical system 30. The projection optical system 30 comprises a projection convergence system 31, a prism 34, an aperture stop 32, and an afocal optical system 33. The projection convergence system 31 is converges the luminous flux made incident from the optical modulation light 9 and this luminous flux passes through the prism 34 and is refracted upward to the travel direction of light to pass through the aperture stop 32, thereby prescribing the external edge of a projection image. The luminous flux having passed through the aperture stop 32 is enlarged by the afocal optical system 33 at a rate corresponding to its angular power and projected on a screen 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical projector, and more particularly, to a structure of a projection optical system of an optical projector.

[0002]

2. Description of the Related Art Generally, a conventional optical projector (projection display device, projection display device, projection display device), for example,
In overhead projectors (OHP), slide projectors, liquid crystal projectors, etc., transparent films,
A light modulating layer (light modulating means) constituted by a slide, a liquid crystal panel, or the like is irradiated with light, and a light beam constituted by the transmitted light is projected forward by a projection optical system, for example, a projected image is formed on a screen. It has become.

[0003] In such an optical projector,
For example, light emitted from a light source such as a metal halide lamp is condensed by an illumination optical system, and the light modulation layer (a layer having an optical function for obtaining a desired image by modulating a light beam in a predetermined pattern) I do. That is,
As shown in FIG. 9, the light from the light source 7 is condensed by the illumination optical system 8 and is irradiated on the light modulation layer 9. Then, the light transmitted through the light modulation layer 9 is enlarged and projected on the screen 20 by the projection optical system 10. FIG. 11 shows a projection optical system 1.
0 shows a configuration example. The light that has passed through the light modulation layer 9 is condensed by a projection light condensing system 11 that is called a master lens and includes a plurality of optical lens groups. The collected light is incident on an afocal optical system 13 including a plurality of optical lenses via an aperture stop 12. The afocal optical system 13 enlarges and projects an image according to the angular magnification.

[0004]

However, when the above-mentioned conventional optical projector is installed on a desk having a horizontal installation surface and an image is to be projected on a screen arranged in front, FIG. As shown, the optical axis A1 from the light modulation layer 9 to the screen 20 via the projection optical system 10 is normally set in a horizontal direction parallel to the installation posture of the optical projector, so that a projected image formed on the screen is formed. Since part of P1 is projected below the desk, it is difficult to visually recognize it. Therefore, when an optical projector is placed on a desk for use in a conference or the like, there is a problem that the projector must be installed in a posture inclined obliquely upward toward the screen.

On the other hand, as one means for solving the above problem, as shown in FIG. 10, the optical axis A1 from the light source 7 to the light modulation layer 9 is positioned below the optical axis A2 of the projection optical system 10. There is a method of forming a projection image P2 that is deviated upward from the projection optical system 10 onto the screen 20 by shifting the projection optical system 10. By doing so, the projected image P2 is formed above the projected image P1 on the screen 20, so that the image is easily visible. However, in this case, the optical axis A of the light beam transmitted through the light modulation layer 9 is
1 is shifted downward, the image area I2 passing through the optical system is shifted downward compared to the image area I1 shown in FIG. 9, so that the effective image circle S2 is wider than the effective image circle S1, and The range in which aberration correction in the system is required is expanded.
That is, as shown in FIG. 8, a light beam emitted from the light modulation layer 9 and projected so as to form an image P2 on the screen 20 is defined by the aperture stop 12, but the light modulation layer 9 is moved from the optical axis. By shifting, the range in which the projection light beam passes through the projection light condensing system 11 and the afocal optical system 13 is limited, and the areas 11a and 13a where the light beam does not pass, as shown by oblique lines in the figure, become large. As a result, the number of lenses constituting the optical system for aberration correction increases,
It is necessary to use a large-area aspherical lens or the like, and there is a problem that manufacturing costs increase.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a projection image which can be formed at a position higher than an installation surface of an optical projector.
An object of the present invention is to provide a structure capable of reducing a manufacturing cost without expanding an effective image circle.

[0007]

In order to solve the above problems, an optical projector according to the present invention comprises a light source, a light modulating means for modulating light incident from the light source to obtain a projected image, and the light modulating means. A projection optical system that emits a projection light beam modulated by a projection optical system, wherein the projection optical system includes: a projection light collection system that collects the light beam; and a light beam formed by the projection light collection system. A light deflecting means for deflecting light and an afocal optical system for emitting a light beam deflected by the light deflecting means are provided.

According to the present invention, the light beam passing through the projection optical system is deflected by the light deflecting means and guided to the afocal optical system, so that the light beam is emitted from the afocal optical system without shifting the light modulating means from the optical axis. Can be directed obliquely without changing the optical system of the optical projector significantly, and without providing an unnecessary area in the optical system where the projection light does not pass, according to the deflection direction of the light deflecting means. Therefore, the image can be formed such that the center position of the projected image is shifted with respect to the position where the extension of the optical axis passing through the light modulating means intersects with the projection plane (screen). The position can be set arbitrarily. Also, by bending the optical axis by the light deflecting means, the light modulating means can be configured without being shifted from the optical axis, so that the effective image circle can be reduced.
It is easy to correct aberrations in the optical system, such as by reducing the area of the optical surface that requires aberration correction, and it is also possible to project a large image using a small-diameter optical element, or reduce the number of lenses For example, since the configuration of the optical system can be simplified, the manufacturing cost can be reduced.

In the present invention, it is preferable that the light beam between the projection light focusing system and the afocal optical system is configured to be substantially parallel light beam. Since the light beam between the projection light condensing system and the afocal optical system is configured to be almost parallel light beam, the light beam passing through the light deflecting means is almost parallel light beam, so the aberration due to the arrangement of the light deflecting means Since there is almost no need to consider correction, there is also an advantage that the optical system is not complicated.

In the above invention, the light path on the output side of the light deflecting means is greatly inclined with respect to the installation surface of the optical projector as compared with the light path on the light source side of the light deflecting means. In some cases, the optical path on the light source side of the light deflecting unit is inclined more greatly with respect to the installation surface of the optical projector than the optical path on the exit side of the light deflecting unit. In the former case, the projection direction of the projected light beam is inclined with respect to the installation surface, so keystone distortion and vertical linearity distortion are likely to occur unless the projection surface such as a screen is inclined with respect to the installation surface. A position where the projected image is easily separated from the installation surface by the inclination of the light emitting direction (for example, an upper position)
Can be formed. In the latter case, since the emission direction of the projection light beam and the installation surface can be set parallel or the angle between the emission direction and the installation surface can be set small, it is possible to suppress the occurrence of keystone distortion and vertical linearity distortion. it can. Also, since the light path on the light source side of the light modulating means is greatly inclined, the distance from the installation surface to the light emitting portion of the optical projector becomes large, so that the projected image is located at a position (for example, an upper position) separated from the installation surface. Can be formed.

In the present invention, the optical axis from the projection optical system to the afocal optical system through the light deflecting means and the optical axis of the afocal optical system may be shifted from each other. preferable.

According to the present invention, the optical axis from the projection optical system to the afocal optical system via the light deflecting means is shifted with respect to the optical axis of the afocal optical system. Can be formed by shifting the center position of the projected image with respect to the position where the extension of the optical axis of the afocal optical system intersects the projection plane, so that the image position can be set according to the situation. Will be possible.

Here, the optical axis from the projection optical system to the afocal optical system via the light deflecting means is shifted upward or downward with respect to the optical axis of the afocal optical system. Preferably, the light deflecting means is configured to deflect the light flux upward or downward.

In each of the above inventions, the light deflecting means is preferably a prism.

[0015] In each of the above inventions, it is preferable that an aperture stop is provided between the projection light condensing system and the afocal optical system. The presence of the aperture stop makes it possible to reliably define the luminous flux forming the image.

In the present invention, when the optical axis is bent by a light deflecting means such as a prism between the projection optical system and the afocal optical system, the position of the light modulating means with respect to the optical axis is shifted as in the prior art. Similarly to the above, the position of the projection image can be formed at a position shifted from the optical axis. In the present invention, there is no need to cause the projection light beam to be deviated with respect to the optical axis of the optical system unlike the related art. Therefore, since the position of the projected image can be shifted from the optical axis while projecting the projection light beam along the optical axis, the effective image circle can be reduced without reducing the brightness even if the image area is the same as the conventional one. can do. Here, the bending angle of the optical axis bent by the light deflecting unit can be set according to the amount of deviation of the projected image.

[0017]

Next, an embodiment of an optical projector according to the present invention will be described in detail. FIG. 1 is a schematic diagram illustrating a configuration of a projection optical system in the optical projector according to the present embodiment. Here, the solid line in the drawing shows the configuration of the present embodiment, and the broken line in the drawing shows the same configuration as the conventional example shown in FIGS. The light modulating layer 9 is made of a light-transmitting film, a slide, a liquid crystal panel, etc. as in the conventional example. It is substantially the same as the projection light condensing system 11, the aperture stop 12, the afocal optical system 13, and the screen 20. However, the luminous flux and the configuration position of the optical system in the figure are schematically drawn,
Distances and ratios are different from actual ones.

Light emitted by a light source and an illumination optical system (not shown) passes through the light modulation layer 9 and enters the projection optical system 30. The projection optical system 30 includes a projection light collecting system 31, a prism 3
4, an aperture stop 32, and an afocal optical system 33. The projection light condensing system 31 has the same structure as the conventional structure shown in FIG. 11 and is for condensing a light beam incident from the light modulation layer 9 to form a focusable projected image. The light flux further passes through the prism 34 and is refracted upward in the light traveling direction, passes through the aperture stop 32, and defines the brightness of the projected image. The light beam that has passed through the aperture stop 32 is magnified by the afocal optical system 33 at a rate corresponding to the angular magnification and projected onto the screen 20. Here, the afocal optical system 33 also has substantially the same configuration as that shown in FIG. 11, and the distance between the lenses in the afocal optical system 33 or the distance between the projection light condensing system 31 and the afocal optical system 33. Is variable, and the focal position of the projected image can be changed according to the distance between the lenses in the afocal optical system 33.

As the prism 34, various prisms capable of bending the optical axis can be used. For example, in the present embodiment, in order to improve chromatic aberration and the like,
The first optical member 34a such as "F2" and the second optical member 34b such as "BSC7" are bonded to each other.

In this embodiment, the optical axis A3 extending from the light modulation layer 9 to the aperture stop 32 via the projection optical system 31 and the prism 34 is defined by the projection optical system 31 and the afocal optical system 3.
3 is curved due to the arrangement of the prism 34 therebetween. Here, by arranging the light modulating layer 9 and the projection condensing system 31 slightly obliquely with respect to the aperture stop 32 and the afocal optical system 33 as shown in the figure, the light modulating layer 9 is A configuration optically substantially equivalent to a case where the optical axis is shifted downward with respect to the axis (the optical axis of the optical system including the projection optical system, the aperture stop, and the afocal optical system) can be obtained. For this reason, the central ray of the light beam from the prism 34 is incident on the upper side of the optical axis of the afocal optical system 33. As a result, in this afocal optical system 33, the central light ray of the projection light beam is also reflected by the afocal optical system 33. Emitted from above the axis. Therefore, on the screen 20,
A projection image P3 having a center point above the point where the extension lines of the optical axis A3 intersect is formed.

In the present embodiment, the light modulation layer 9
The optical axis A3 to the projection optical system 31, the prism 34 and the aperture stop 32 may be shifted with respect to the optical axis A4 of the afocal optical system 33. FIG. 2 shows the configuration of the optical system in such a case. In this case, the optical axis A3 is slightly shifted downward with respect to the optical axis A4.

In this embodiment, as shown in FIGS. 1 and 2, the effective image plane S3 can be made small by an image area I3 formed around the optical axis A3. That is, as shown in FIG. 7, even if the light modulation layer 9 is not shifted downward with respect to the optical axis A3 of the optical system, the projection image P3 is formed slightly above the projection image P2 shown in FIG. Therefore, it is not necessary to allow a light beam for forming a projection image projected on the screen 20 from the light modulation layer 9 to pass through the optical system in a state deviated from the optical system. Since the configuration of the optical system is simplified, manufacturing costs can be reduced.

Further, in the present embodiment, the light flux between the projection light condensing system and the afocal optical system (what becomes the projection light flux)
The optical system is set so that is substantially parallel light flux. Therefore, the light beam that passes through the prism 34 serving as the light deflecting unit can be basically regarded as a substantially parallel light beam. Therefore, there is no need to consider aberration correction in the prism 34, and the provision of the prism 34 does not unnecessarily complicate the optical system. Such setting of the optical system can be easily performed by appropriately configuring the optical constants and positions of the respective optical elements.

FIG. 3 shows a schematic structure of an optical projector 100 constructed using this embodiment. Here, the optical projector 100 is a base 19 made of a desk or the like.
Is placed on the installation surface 19a. The light emitted from the light source 7 is condensed by the illumination light condensing system 8, passes through the light modulation layer 9, is projected forward by the above-described projection optical system 30, and forms a projection image P <b> 3 on the screen 20. At this time, the central ray of the projection light beam is directed obliquely upward, and as a result, the projected image P3 on the screen 20 is
The optical projector 100 is formed at a position where the optical projector 100 is installed, that is, above the installation surface 19a.

In this configuration example, the light source 7 and the projection optical system 3
The optical axis up to 1 is tilted slightly downward toward the front, and from the prism 34 through the aperture stop 32 to the afocal optical system 33.
The optical axis is configured to be horizontal (parallel to the installation surface 19a). However, in the optical projector 100, the portion of the optical axis A3 from the light source 7 to the projection light condensing system 31 is configured to be substantially parallel (horizontal) to the installation surface 19a, and the optical axis A3 is inclined obliquely upward by the prism 34. You may comprise so that it may bend. Further, in the optical axis shown in FIG. 3, the optical axis A3 coincides with the optical axis of the afocal optical system 33, but as shown in FIG. On the other hand, it may be shifted slightly downward. However, in this case, the optical axis A4 of the afocal optical system 33 is set parallel to the part of the optical axis A3 bent obliquely upward.

In the embodiment shown in FIGS. 2 and 4, the optical axis A3 and the optical axis A4 are configured to be parallel to each other, but the optical axis A3 and the optical axis A4 are slightly inclined (tilted) from each other. ), Distortion of the projected image formed on the screen (keystone distortion, vertical linearity distortion, etc.)
Can be reduced.

In this embodiment, the projection image P3 can be formed at a position higher than the conventional projection image P1 by the refraction angle of the light beam by the light deflecting means such as the prism 34. That is, the extension of the optical axis A4 is
Is located above the point where the extension of the conventional optical axis A2 intersects the screen 20, and the center position of the projected image P3 is that the extension of the optical axis A4 intersects the screen 20. It is located above the point.

Next, a modification of the above embodiment will be described with reference to FIG.
This will be described with reference to FIG. In this modification, the arrangement of the light modulation layer 9, the prism 44, the aperture stop 32, and the afocal optical system 33 is the same as in the above embodiment. In this modification, the direction of light deflection by the prism 44 is different from that of the above embodiment, and the optical axis A3 from the light modulation layer 9 to the aperture stop 32 through the prism 44 is bent downward by the prism 44 in the light traveling direction. are doing. In the case shown in FIG. 6, the optical axis A3 from the projection optical system 31 to the afocal optical system 33 via the prism 44 is shifted upward with respect to the optical axis A4 of the afocal optical system 33. ing.

In the projector 200, the light source 7
An illumination optical system from to an irradiation optical system 8, a light modulation layer 9,
The portions from the projection light condensing system 31 to the prism 44 are sequentially arranged obliquely upward in the light traveling direction, and the light beam passing through each of these optical elements also travels obliquely upward. The light flux travels substantially horizontally from the prism 44 to the afocal optical system 33 and is emitted forward of the projector 200. When the projector 200 is installed on the installation surface 19 a of the base 19 as shown in FIGS. 5 and 6, the prism is moved relative to the position of the light source 7 mainly because the optical path on the light source 7 side is inclined with respect to the prism 44. The positions of 44 and the afocal optical system 33 are arranged at higher positions.

In this modification, the projection image P4 is formed above the installation surface 19a because the optical axis A3 is inclined upward and forward as a whole. In the case shown in FIG. 6, since the optical axis A4 is slightly shifted downward with respect to the optical axis A3, the projection image P4 is formed slightly below, but the optical axis A3 and the optical axis A4 are still basically different. , The center point of the projected image P4 on the screen 20 is located above the installation surface 19a,
It is configured such that the projection image P4 can be viewed well.

In the embodiment shown in FIG. 6, the optical axis A3 and the optical axis A4 are configured to be parallel to each other, but the optical axis A3 and the optical axis A4 are slightly tilted relative to each other. Thereby, the distortion of the projected image formed on the screen can be reduced, and the occurrence of the keystone distortion and the vertical linearity distortion can be suppressed.

It should be noted that the optical projector of the present invention is not limited to the above-described illustrated example, and it is needless to say that various changes can be made without departing from the scope of the present invention. For example, in the above embodiment, as the afocal optical system, an optical system in which images before and after transmission are not inverted is used. However, even in the same afocal optical system, an optical system in which images before and after transmission are inverted is used. May be used. However, in this case, the direction in which the optical axis of the light beam incident on the afocal optical system is deviated from the optical axis of the afocal optical system, and the center of the projection light beam emitted from the afocal optical system are the afocal optical system. The directions deviating from the optical axis of the system are opposite to each other. Therefore, in order to form a projection image upward by obtaining a projection light beam shifted upward with respect to the optical axis of the afocal optical system as in the above-described embodiment, the optical axis of the light beam incident on the afocal optical system must be changed. It is necessary to shift the optical axis of the afocal optical system downward.

In the above embodiment, the position of the aperture stop can be arbitrarily set as long as it is between the light exit position of the projection light condensing system and the light entrance position of the afocal optical system. Furthermore, although the light source 7 and the illumination optical system 8 of the above embodiment are only schematically shown, various optical paths can be formed and appropriate configurations can be made using various optical elements.

[0034]

As described above, according to the present invention,
Since the light beam that has passed through the projection optical system is deflected by the light deflecting device and guided to the afocal optical system, the projection light beam emitted from the afocal optical system is directed obliquely without shifting the light modulating device from the optical axis. Therefore, the light passing through the light modulating means can be changed according to the deflection direction of the light deflecting means without largely changing the optical system of the optical projector and providing the optical system with a useless area through which the projection light beam does not pass. Since the image can be formed so that the center position of the projected image is shifted from the position where the extension line of the axis intersects the projection plane (screen), the image position can be set arbitrarily according to the situation become.

Further, by bending the optical axis by the light deflecting means, the light modulating means can be configured without being shifted from the optical axis, so that the effective image circle can be reduced, and the area of the optical surface requiring aberration correction is reduced. As a result, aberration correction of the optical system becomes easy, and a large image can be projected using a small-diameter optical element.
Alternatively, since the configuration of the optical system can be simplified, for example, the number of lenses can be reduced, the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a projection optical system in an embodiment of an optical projector according to the invention.

FIG. 2 shows a light modulation layer, a projection light condensing system,
The optical axis A3 of the prism and the aperture stop is set to the afocal optical system A.
FIG. 4 is a schematic configuration diagram illustrating a configuration in a case of being shifted with respect to FIG.

FIG. 3 is a schematic diagram showing a state in which the embodiment shown in FIG. 1 is arranged on a base.

FIG. 4 is a schematic diagram showing a state in which the embodiment shown in FIG. 2 is arranged on a base.

FIG. 5 is a schematic configuration diagram showing a modification of the embodiment.

FIG. 6 is a diagram illustrating an optical axis A3 of a light modulating layer, a projection light condensing system, a prism, and an aperture stop in the above-described modified example;
FIG. 4 is a schematic configuration diagram showing a configuration in a case where the configuration is shifted with respect to FIG.

FIG. 7 is an explanatory diagram illustrating an optical system and an optical path according to the present embodiment.

FIG. 8 is an explanatory diagram showing a conventional optical system and an optical path.

FIG. 9 is a schematic explanatory view showing an optical system of a conventional optical projector and an effective image circle thereof.

FIG. 10 is a schematic explanatory view showing an optical system of a different conventional optical projector and an effective image circle thereof.

FIG. 11 is a schematic optical system configuration diagram showing a configuration example of a projection optical system in a conventional optical projector.

[Explanation of symbols]

 Reference Signs List 7 light source 8 illumination condensing system 9 light modulation layer 20 screen 30 projection optical system 31 projection condensing system 32 aperture stop 33 afocal optical system 34,44 prism 100,200 optical projector

Claims (6)

[Claims] 1. An optical projector comprising: a light source; a light modulator for modulating light incident from the light source to obtain a projection image; and a projection optical system for emitting a projection light beam modulated by the light modulator. In the projection optical system,
A projection focusing system for focusing the light beam; a light deflecting unit for deflecting the light beam formed by the projection focusing system; and an afocal optical system for emitting the light beam deflected by the light deflecting unit. An optical projector, comprising: 2. The optical projector according to claim 1, wherein a light beam between the projection light focusing system and the afocal optical system is configured to be a substantially parallel light beam. 3. An optical axis of the afocal optical system according to claim 1 or 2, wherein an optical axis from the projection light focusing system to the afocal optical system via the light deflecting means and incident on the afocal optical system. An optical projector characterized by being shifted from each other. 4. The optical axis of the afocal optical system according to claim 3, wherein an optical axis from the projection optical system to the afocal optical system via the light deflecting means is higher or lower than the optical axis of the afocal optical system. The optical projector, wherein the optical deflecting means is configured to deflect the light flux upward or downward while being shifted. 5. The method according to claim 1, wherein:
9. The optical projector according to claim 1, wherein the light deflecting unit is a prism. 6. Any one of claims 1 to 5
9. An optical projector according to claim 1, further comprising an aperture stop disposed between the projection light condensing system and the afocal optical system.